We investigated the adsorption properties of propylene and propane on an olefin-selective Ag-X membrane and discussed the contribution of adsorption selectivity to propylene/propane separation performance through this membrane. The isotherms of propylene and propane on Ag-X membranes were measured in unary systems at 313 K. The amount of propylene adsorbed on the Ag-X membrane at a lower pressure increased remarkably compared with that on the Na-X membrane. Such a change of adsorption property could induce excellent separation property for the Ag-X membrane. We compared the adsorption properties in a binary system calculated based on the Markham-Benton approach with the results of a permeation test. The molar fractions of propylene in the adsorbed phase in the binary system provided good agreement with propylene purity on the permeation side of the Ag-X membrane. These results clearly show that permeation selectivity of the Ag-X membrane for the propylene/propane mixture is mainly governed by adsorption selectivity.

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. T. Developing a novel ammonia synthesis process from N2 and H2 is of interest to the catalysis and hydrogen research communities. γ-Alumina-supported nickel was determined capable of serving as an efficient catalyst for ammonia synthesis using nonthermal plasma under atmospheric pressure without heating. The catalytic activity was almost unrelated to the crystal structure and the surface area of the alumina carrier. The activity of Ni/Al2O3 was quantitatively compared with that of Fe/Al2O3 and Ru/Al2O3, which contained active metals for the conventional Haber–Bosch process. The activity sequence was Ni/Al2O3 > Al2O3 > Fe/Al2O3 > no additive > Ru/Al2O3, surprisingly indicating that the loading of Fe and Ru decreased the activity of Al2O3. The catalytic activity of Ni/Al2O3 was dependent on the amount of loaded Ni, the calcination temperature, and the reaction time. XRD, visual, and XPS observations of the catalysts before the plasma reaction indicated the generation of NiO and NiAl2O4 on Al2O3, the latter of which was generated upon high-temperature calcination. The NiO species was readily reduced to Ni metal in the plasma reaction, whereas the NiAl2O4 species was difficult to reduce. The catalytic behavior could be attributed to the production of fine Ni metal particles that served as active sites. The PN2/PH2 ratio dependence and rate constants of formation and decomposition of ammonia were finally determined for 5.0 wt % Ni/Al2O3 calcined at 773 K. The ammonia yield was 6.3% at an applied voltage of 6.0 kV, a residence time of reactant gases of 0.12 min, and PH2/PN2 = 1.

© 2020 Journal of Visualized Experiments. Membrane separation has drawn attention as a novel-energy saving separation process. Zeolite membranes have great potential for hydrocarbon separation in petroleum and petrochemical fields because of their high thermal, chemical, and mechanical strength. A *BEA-type zeolite is an interesting membrane material because of its large pore size and wide Si/Al range. This manuscript presents a protocol for *BEA membrane preparation by a secondary growth method that does not use an organic structure-directing agent (OSDA). The preparation protocol consists of four steps: pretreatment of support, seed preparation, dip-coating, and membrane crystallization. First, the *BEA seed crystal is prepared by conventional hydrothermal synthesis using OSDA. The synthesized seed crystal is loaded on the outer surface of a 3 cm long tubular α-Al2O3 support by a dip-coating method. The loaded seed layer is prepared with the secondary growth method using a hydrothermal treatment at 393 K for 7 days without using OSDA. A *BEA membrane having very few defects is successfully obtained. The seed preparation and dip-coating steps strongly affect the membrane quality.

© 2019 The Authors A potential of zeolite membrane in forward osmosis operation was investigated for the first time. A hydrophilic zeolite, ZSM-5, membrane was prepared on an α-alumina tubular support by a secondary growth method. NaCl aqueous solution and distilled water were used as draw and feed solutions, respectively. The membrane exhibited a water flux of 2.2 L m−2 h−1 with a salt flux of 0.69 g m−2 h−1 at 313 K by using 9.0 wt% draw solution. ZSM-5 membrane showed a quite small reverse salt flux based on a molecular sieving effect in the relatively wide temperature ranges of 298–333 K. ZSM-5 membrane also kept its performance under acidic conditions. In addition, obvious deterioration of the membrane performance was not observed after intermittent use of our membrane for more than one month.

© 2019 The Authors Tubular zeolite *BEA membrane was prepared by a hydrothermal secondary growth method in the absence of an organic structure directing agent (OSDA). Membrane formation process was carefully observed by using FE-SEM, XRD, and N2 adsorption, and the role of seed crystals on the support surface was discussed. Seed crystals loaded on the outer surface of a tubular porous alumina support partially dissolved and a small amount of seeds remained in an amorphous layer formed on the support surface in the early stage of secondary growth step. Subsequently, crystal growth of remaining crystals occurred, and a continuous *BEA layer was obtained following crystallization for 7 days at 393 K. In the secondary growth step, the supported seed layer played an important role in inducing the formation of a high local concentration in the vicinity of the support surface. The prepared OSDA-free *BEA membrane was then applied in the separation of hydrocarbons. We found that this membrane contained very few defects, and exhibited a high ideal selectivity for cyclohexane/1,3,5-trimethylbenzene mixture of 100, with cyclohexane permeance of 1.0 × 10−7 mol m−2 s−1 Pa−1 based on molecular sieving effect at 623 K.

© 2019 American Chemical Society. Propylene/propane and ethylene/ethane separation was examined with Ag-exchanged X-type zeolite membrane (Ag-X membrane). The Na-X membrane was prepared on a porous tubular α-alumina support by a secondary growth method. The resulting Na-X membrane was ion-exchanged by using AgNO 3 aq. Olefin selectivities in both mixtures were markedly improved after the ion exchange from Na to Ag cation. The Ag-X membrane exhibited a maximum propylene selectivity of 55.4 with a permeance of 4.13 × 10 -8 mol m -2 s -1 Pa -1 at 353 K for a propylene/propane (50:50) mixture. This membrane also exhibited a maximum ethylene selectivity of 15.9 with a permeance of 9.04 × 10 -8 mol m -2 s -1 Pa -1 at 303 K for an ethylene/ethane (50:50) mixture. We consider that the strong interaction between olefin and Ag cation plays an important role for the appearance of such high selectivity of olefin.

© 2018 Hydrogen Energy Publications LLC The plasma decomposition of ammonia was studied as a function of applied voltage/power, residence time including length of an inner electrode and flow rate of reactant gases, partial pressure of ammonia, and amount and the metal species of the inner electrodes. The ammonia decomposition rates were in excellent agreement with the hydrogen production rates and no hydrazine production was detected, indicating the clean decomposition of ammonia in the current system. The decomposition rates were dependent on the applied power and the residence time and independent of metal species of the inner electrodes, in contrast to the strong dependence of the ammonia synthesis reaction on the metal species. A hydrogen yield of 100% was achieved with an applied power of approximately 50 W and a residence time of 1.2 s at ambient temperature and atmospheric pressure, with an applied voltage of 5 kV and a frequency of 50 kHz.

© 2018 American Chemical Society. A superheated steam (SHS) treatment was found to be effective for conversion of cellulose to levoglucosan (LG) and other organic compounds. Yields of water-soluble organic compounds (TOC) and LG reached 88% and 41%, respectively, with the SHS treatment at 300 °C for 30 min. The reaction temperature was far lower than temperatures employed in conventional pyrolysis treatments (≥500 °C), and the TOC and LG yields were comparable to values reported for pyrolysis. Product distributions were significantly altered by sodium content in the parent cellulose. Sodium at 0.05 wt % or more in cellulose lowered the LG yield to almost zero, giving approximately constant TOC values other than LG, and increased solid residue, which indicated that sodium greatly reduced the reactivity of cellulose to form LG. In the absence of sodium, the reactivity of the crystalline phase of cellulose was much higher than the amorphous phase, indicating that the widely reported phenomena in which amorphous cellulose has higher reactivity than crystalline cellulose might result from a sodium impurity. In addition, the effect of ball-milling treatment was investigated to reveal the reactivity of crystalline and amorphous phases of cellulose with or without sodium contamination. The crystalline phase was converted to an amorphous phase distinct from the original amorphous phase, which could be distinguished by XRD patterns. The reactivity of the new amorphous phase was higher than that of the original crystalline phase. The obstruction of the LG formation by sodium was suggested to be due to its coordination onto a terminal glucose unit of a cellulose nanocrystal, based on the cellulose structure and amounts of sodium.

Zeolites demonstrating better SCR of NOx performance due to wide temperature activity, hydrothermal stability and N-2 selectivity have been identified under a joint research initiative by the Research Association of Automotive Internal Combustion Engines (AICE), Japan. Based on the AICE's standards, over 25 zeolites with different structures and pore dimensions were investigated and their SCR efficiency and durability have been compared. While the performances of the top contenders cannot be related to a single parameter, the results suggest that the SAR, Cu quality/quantity, pore dimensions, diffusivity and acidity play a combined role in deciding the SCR activity and selectivity.

We have successfully investigated nitrogen adsorption measurement using ZSM–5 type zeolite membrane prepared by seed assisted hydrothermal synthesis with various crystallization periods under non–destructive condition. Micro– and meso–pores derived from zeolitic and non–zeolitic structures were analyzed using nitrogen adsorption isotherm with the Saito–Foley model and the Kelvin equation. ZSM–5 membranes synthesized for various crystallization periods were characterized and evaluated by SEM, XRD, nanopermporometry and permeation tests. In this study, it could be considered that ZSM–5 membrane formation process had two–step as follows. First, ZSM–5 seed crystal was grown up in/onα–alumina support, and ZSM–5 micro–crystals generated in pore ofα–alumina support until 6 hours synthesis. After that, ZSM–5 crystals on theα–alumina support surface were predominantly grown up, and these crystals covered the support surface. After synthesis of 12 hours, the membrane had hardly defects.

Highly stable FAU-type zeolite membrane for the separation of isopropanol (IPA)-water mixture by pervaporation is described. FAU membrane showed high water permselectivity and permeance. Comparison of FAU membrane with a conventional LTA-type zeolite membrane revealed superior stability of FAU zeolite membrane in a mixture containing a large water content.

Structures of platinum and chromium supported on zeolite beta were investigated by XAFS, XPS, UV-vis, NH3-TPD, XRD, CO chemisorption, and molecular dynamics simulation. Both platinum and chromium were uniformly dispersed in the micropore of zeolite beta. Loading of chromium helped platinum to disperse highly and stabilized in the micropore of beta. Major species of platinum on PtCr/beta after calcination at 773 K was Pt2+ forming a Pt-O bond. The Pt-O bond disappeared, and a Pt-Pt bond did not appear by reducing PtCr/beta in hydrogen, accompanying formation of Pt-0. Chromium was loaded as chromate anion in the micropore of zeolite. Results of molecular dynamics simulation showed that Pt2+ associated with CrO42- in the micropore of zeolite beta was more stable than those in the absence of chromium species. We concluded that CrO42- electrostatically stabilizes Pt2+ and inhibits migration and aggregation of platinum.

Silicalite-1, a pure silica MFI-type zeolite, membrane was prepared on a tubular a-alumina support by a secondary growth method. Separation of n-alkane from a mixture of hydrocarbons was carried out by using silicalite-1 membrane. We report the permeation and separation properties for n-alkanes having different carbon numbers.  

Catalysis of Pt/beta zeolite catalyst modified via the addition of various elements (Ca, Cr, Mn, Fe, Co, Ni or Cu) for n-heptane skeletal isomerization was investigated at 513 K in a conventional flow reactor with a fixed catalyst bed. It was found that, among the catalysts tested, PtCr/beta was the most promising, since its use resulted in relatively high yields of multi-branched alkanes in conjunction with a very low selectivity for cracking products. Ion exchange was found to be an effective method for the addition of chromium to zeolite, compared to the evaporation to dryness process. Platinum particle sizes were observed using STEM. While particles similar to 10-30 nm in size were evident on the surface of Pt/beta, they were rarely observed on the PtCr/beta catalyst. It was concluded that platinum homogeneously dispersed within beta zeolite micropores resulted in the observed decreased cracking activity during n-heptane isomerization and that the addition of chromium had been effective in increasing degree of platinum dispersion.

Reduction of energy consumption in the industry sector, especially chemical industry, is strong demand. In chemical industry about 40% of the total energy consumption is for distillation. Thus, reduction of the energy used in distillation by introducing membrane technology would have strong impact. Zeolites, a class of microporous ceramic materials, have superior physicochemical properties, such as molecular sieving and preferential adsorption, in addition to high thermal, chemical, and structural stability. In this report, development of zeolite membranes will be emphasized to be attractive as a strong candidate enabling us to reduce energy consumption in chemical industry. In particular, we have started operation of a bench-scale test plant for the separation of water and isopropyl alcohol (IPA) at the production site of IPA, Kawasaki, Japan. This is the first on-site test plant using ceramic membrane in petrochemical industry. Also, acid-resistant zeolite membrane has been developed for the dehydration of acetic acid.

Separation property of silicalite-1 membrane for C₁₀ hydrocarbons was investigated. Silicalite-1 membrane was prepared on a tubular support (pore size = 0.15 μm, i.d. = 7 mm, o.d. = 10mm) by secondary-growth method. n-Decane, n-butylbenzene and tetralin were used for model substance of C₁₀ hydrocarbons. n-Decane and n-butylbenzene could penetrate through the membrane but tetralin permeation was not observed. Thus permeance ratio of n-decane to tetralin was over 100. As a result, it was shown that C₁₀ hydrocarbons can be separated with silicalite-1 membrane by molecular sieving effect.

Oxidation of carbon particles by lattice oxygen on/in catalysts was investigated with and without electrical discharge at 673 K in a fluidized bed reactor. Application of dielectric barrier discharge promoted the evolution of lattice oxygen in the oxide catalyst, and oxidation of carbon by the evolved lattice oxygen was accelerated by application of the discharge. The total amount of consumed lattice oxygen in/on the catalyst was not changed by the application of the discharge due to the low diffusion rate of bulk oxygen at low temperature. Metal-loaded catalysts such as Ni/CeO2 evolved larger amounts of lattice oxygen because of interaction between the supported Ni particle and ceria support. (C) 2011 Elsevier Ltd. All rights reserved.

DGC-H-beta zeolite catalyst has higher activity and selectivity for the alkylation of isobutane with 1-butene in a CSTR. The cause of the deactivation of the catalyst and the optimum reaction conditions were investigated. Deactivation of the catalyst was caused not by adsorbed carbon species but by hydrocarbons formed by multiple alkylation or oligomerization of olefin. Optimized conditions to avoid these reactions achieved stable selective alkylation.

The effects of zeolite structures on alkylation of isobutane with 1-butene were investigated in a batch reactor and in a continuously stirred tank reactor (CSTR) using the proton-form zeolites, H-ZSM-5, H-L, H-Y, and H-*BEA (beta). H-ZSM-5 and H-L zeolite catalysts were deactivated rapidly, whereas H-Y and H-*BEA zeolites retained catalytic activity for a long time in the CSTR, implying that zeolites with three-dimensional large pore systems are useful for preventing deactivation of the catalyst during alkylation of isobutane with 1-butene. H-*BEA synthesized using a dried-gel method (DGC-H-*BEA) showed the most stable activity among the various H-*BEA zeolites. The effects of the synthesis methods and zeolite characteristics were investigated using H-*BEA zeolite. Characterization using NH3-TPD and pyridine-sorption monitored by FT-IR showed that high acid density and high Bronsted acid ratio promoted alkylation of isobutane with 1-butene over H-*BEA zeolite.

Oxidative coupling of methane (OCM) on La2O3 semiconductor catalysts at 423 K external temperature was investigated. DC power supplied from two electrodes in a catalyst bed enabled stable and selective production of C2H6 and C2H4 over Sr-La2O3 (Sr/La = 1/200 and 1/20), but plasma reactions proceeded over other catalysts. The electrical conductivity of the semiconductor catalyst was important for controlling this reaction. A high yield of C2 (49% selectivity, 51.3% O-2 conversion) was obtained using 2.7 W of electricity at a lower external temperature (423 K).

We found that LalnO(3) perovskite catalyst showed high activity for oxidative coupling of methane (OCM). Partial substitution of La3+ site in the LalnO(3) catalyst with Ba2+ increased its catalytic activity and selectivity to C2 hydrocarbons drastically. The partial substitution of La3+ site in LalnO(3) with Ba2+ increased oxygen vacancies in the stable cubic phase, and then contributed to the production of active oxygen species on its surface for selective C2 formation.

Catalytic steam reforming of methane in an electric field (named "electreforming") was conducted over metal catalysts supported on CeO2 or CexZr1-xO2 at low temperatures such as 423 K where conventional catalytic reactions hardly proceeded. The conversion of methane was greatly increased by weak and effective application of an electric field to the catalyst bed. Use of CexZr1-xO2 as a catalyst support promoted electreforming, the lattice oxygen of CexZr1-xO2 playing an important role. Energy efficiency of electreforming, reaction mechanism, and the role of lattice oxygen were investigated and are discussed in this paper. (C) 2011 Elsevier B. V. All rights reserved.

Dry reforming of diesel fuel, an endothermic reaction, is an attractive process for on-board hydrogen/syngas production to increase energy efficiency. For operating this dry reforming process in a vehicle, we can use the exhaust gas from an exhaust gas recirculation (EGR) system as a source of carbon dioxide. Catalytic dry reforming of heavy hydrocarbon is a very difficult reaction due to the high accumulation of carbon on the catalyst. Therefore, we attempted to use a non-equilibrium pulsed plasma for the dry reforming of model diesel fuel without a catalyst. We investigated dry reforming of model diesel fuel (n-dodecane) with a low-energy pulsed spark plasma, which is a kind of non-equilibrium plasma at a low temperature of 523 K. Through the reaction, we were able to obtain syngas (hydrogen and carbon monoxide) and a small amount of C(2) hydrocarbon without coke formation at a ratio of CO(2)/C(fuel) = 1.5 or higher. The reaction can be conducted at very low temperatures such as 523 K. Therefore, it is anticipated as a novel and effective process for on-board syngas production from diesel fuel using an EGR system.

Previously we reported that La(0.8)Ba(0.2)Fe(0.4)Mn(0.6)O(3-delta) (LBFMO) perovskite oxide catalyst showed extremely high activity for dehydrogenation of ethylbenzene to produce styrene. The reaction mechanism of dehydrogenation of ethylbenzene over LBFMO catalyst and the role of A/B site cation in the perovskite were investigated using transient response experiments and thermogravimetric analyses in a H(2)O/H(2) atmosphere. Results showed that the dehydrogenation of ethylbenzene over LBFMO perovskite catalyst proceeded via reduction-oxidation (redox) of the perovskite oxide in this temperature range (800-900 K). Thereby, oxidative dehydrogenation of ethylbenzene consumed lattice oxygen in the perovskite; the consumed lattice oxygen was regenerated by H(2)O. We measured the lattice oxygen release rate and regenerating rate over LBFMO perovskite catalyst. The regeneration rate of lattice oxygen was almost equal to the formation rate of styrene in the steady state of the dehydrogenation reaction. Substituting the B site of perovskite with Fe has a stabilizing effect for the lattice oxygen in the perovskite, and enhanced the regeneration rate of lattice vacancy drastically using steam. We concluded that the better stability of LBFMO than that of other catalysts was derived from enhanced lattice oxygen regeneration in the perovskite. (C) 2011 Elsevier B.V. All rights reserved.

This article discusses the directions for energy systems based on an urgent proposal to counter the energy crisis in eastern Japan, published from the Society of Chemical Engineers, Japan. We first illustrate the situation Japan faces, highlighting the urgency and seriousness of the consequences of power outages in industry and daily life. Then, we elaborate on the necessity for policy support to trigger collective actions to temporarily practice countermeasures that would not necessarily save resources or that could disrupt society's established routines. In this way, Japan can choose technologies without regret based on society-wide discussions on the future energy supply. Finally, we warn of the drawbacks induced by shortsighted decisions e. g., avoiding power outages by depending on less-efficient gas turbines. We conclude that Japan should commence a transition of its energy systems rather than compromising resource efficiency and grid robustness over the next decades.

We investigated the effect of loading potassium over iron-based catalysts for water-gas shift (WGS) reaction at 573 K. The iron-based water-gas shift catalyst has been known as a redox-mechanism catalyst. Therefore, to promote the redox reaction over iron oxide, we impregnated a small amount of Pd on various iron oxides. Results revealed that coexisting potassium and palladium accelerated the WGS reaction over iron-oxide catalyst. We examined the optimum amount of potassium over Pd/iron catalyst, and we found that the optimum molar ratio was about 2 (K/Pd molar ratio). From the viewpoint of reducibility of the catalyst, the addition of small amount of Pd onto iron oxide promotes reduction from Fe(2)O(3) to Fe(3)O(4). However, impregnation of potassium on iron oxide makes the catalyst structure robust. The promotion effect of Pd and potassium was not observed on SiO(2) support. We therefore concluded that the synergetic effect among Pd, K, and iron oxide, was important for the WGS reaction.

We examined the promotion effect of loading small amounts of Fe onto various Co catalysts for steam reforming of ethanol. Among these catalysts, catalysts supported on SrTiO3 and alpha-Al2O3 showed remarkable effects of iron loading onto cobalt catalyst. The Fe-loaded Co/alpha-Al2O3 showed higher yield of hydrogen, low coke deposition on the catalysts, and high activity for steam reforming of acetaldehyde, which was an intermediate of the steam reforming of ethanol. Characterization of the catalyst revealed that Fe and Co metal coexisted on the catalyst support. Synergetic effects of these two metals were observed. (C) 2010 Elsevier B.V. All rights reserved.

Catalytic properties of Pd and/or Pt supported/incorporated on/in perovskite-type oxides for water gas shift (WGS) reaction have been investigated. We found that the dominant reaction mechanism over these catalysts was redox mechanism by CO and steam, and their redox properties were controllable by the bulk structure of perovskite.

We investigated four catalytic reactions assisted with in electric field to promote catalytic activity, and we could achieve an effective process for hydrogen production at low temperatures. Such as 423 K. In the presence of the electric field, four reactions of steam reforming of ethanol, decomposition of ethanol, water gas shift, and steam reforming of methane proceeded at very low temperature, Such as 423 K, where a conventional catalytic reaction hardly proceeded. Conversion of reactant was greatly increased by the electric field, Zinc apparent activation energies for these four reactions were lowered by the application of the electric field. This process cart produce hydrogen and syngas by using a considerably small energy demand and has quick response.

We investigated two types of electrical discharges for converting. biomethane into syngas at ambient temperature and atmospheric pressure. Low energy pulsed discharge (LEP) has a good property for this reaction and it could convert biomethane into syngas and also H(2)S was converted into solid sulfur simultaneously. This is due to the high electron energy of LEP, and the electron has enough energy to dissociate C-C bond and C-S bond. On the other hand, dielectric barrier discharge could convert H(2)S into solid sulfur, but methane and CO(2) in the biomethane were not reacted at lower input power. Our investigation showed that proper choice of electric discharge could bring selective reaction for dry reforming of biomethane and desulfurization, and this was due to the correlation between the bond dissociation energy of each molecule and electron energy level of each discharge. (C) 2009 Elsevier Ltd. All rights reserved.

We have studied the effect of steam in the steam-assisted crystallization (SAC) of *BEA-type zeolite. It was found that after an aluminosilicate dry gel with SiO2/Al2O3 = 100 was treated with steam in an autoclave at 130 degrees C and autogenous pressure, the thermal treatment of a resulting product at 130 degrees C in an autoclave without the addition of water gave *BEA nanoparticles with a high crystallinity. It was presumed that pseudo-*BEA structures as intermediates were formed during the SAC treatment, and the dehydration of silanols in the pseudo-*BEA solids during the thermal treatment in the presence of a minimum amount of water possibly promoted the transformation of the pseudo-*BEA phase into *BEA crystalline phase with a periodicity in long-range order.

Steam reforming of ethanol was examined over Co/SrTiO(3) with addition of another metal-Pt, Pd, Rh, Cr, Cu, or Fe-for promotion of the catalytic activity. Ethanol conversion and H(2) yield were improved greatly by adding Fe or Rh at 823 K. Although Rh addition promoted CH(4) formation, Fe addition enhanced steam reforming of ethanol selectively. A suitable amount of Fe loading was in the window of 0.33-1.3 mol%. A comparative study of the reaction over a catalyst supported on SiO(2) was conducted, but no additional effect of Fe was observed on the Co/SiO(2) catalyst. High activity of Fe/Co/SrTiO(3) catalyst came from interaction among Fe, Co, and SrTiO(3).

We investigated novel catalytic reaction systems which were activated by an electric field. This is the first report for the synergetic effect of catalyst and electric field. These catalytic systems showed very high activity compared to conventional catalytic reaction systems. Although Pt supported on CeO(2) catalyst without an electric field showed no activity at 473 K, the addition of an electric field to the catalyst promoted the degradation of ethanol. Pt/CeO(2) catalyst was activated by the electric field and synergetic effect of Pt catalyst and electric field was observed. Thermal analyses showed that about 5-10% of input electrical power was wasted as a heat and about 90-95% was consumed for the endothermic reaction. Catalytic reactions in an electric field proceed under mild conditions and show a quick response. (C) 2009 Elsevier B.V. All rights reserved.

We investigated novel LaMnOx perovskite-oxide (ABO(3)) catalysts for effective catalytic dehydrogenation of ethylbenzene to produce styrene monomer. Comparison with industrial Fe-K catalyst, our La(0.8)Ba(0.2)Mn(0.6)Fe(0.4)O(3-delta) catalyst showed higher activity. Results show that the A-site in perovskite-type oxides affected catalytic dehydrogenation activities and that the B-site affected stability of the activities.

We found that catalytic steam reforming of methane was drastically promoted in an electric field. In the presence of the electric field, reaction proceeded in considerably low temperature region like as 423 K where conventional catalytic steam reforming of methane hardly proceeded. Conversion was greatly increased by impressing the electric field to the catalyst bed. This process can produce hydrogen and syngas by using considerably small energy demand and has a property of quick response.

Water-gas-shift (WGS) reaction is important for hydrogen production process and synthesis gas production process. In the industrial process, high-temperature-shift (HTS) reaction is carried out at 593-723 K using iron-chromium catalyst, and low-temperature-shift (LTS) reaction is carried out below 573 K using copper-zinc catalyst, respectively. There are some problems that the iron-chromium catalyst has low activity at low temperature, and the copper-zinc catalyst is deactivated by cyclic operation like as DSS. Recently we reported that the activity of Pd/Pt/LaCoO3 was higher than the activity of the copper-zinc catalyst and the catalyst did not require reductive pretreatment. The noble metal catalyst is comparatively stable, but the cost of the noble metal catalyst is higher than the iron-chromium catalyst and the copper-zinc catalyst. Therefore it is important to reduce the amount of noble metal.The purpose of this study is to develop the novel catalyst for the WGS reaction in order to decrease the reaction temperature, and we examined the iron oxide catalyst and perovskite type oxide catalyst, expecting to improve the activity and the heat stability with redox properties.

Reverse-selective membranes, through which bigger molecules selectively permeate, are attractive for developing chemical processes utilizing hydrogen because they can maintain the high partial pressure of hydrogen required for their further downstream utilization. Although several of these chemical processes are operated above 473 K, membranes with outstanding reverse-selective separation performance at these temperatures are still to be reported. Herein, we propose a new adsorption-based reverse-selective membrane that utilizes a Na cation occluded in a zeolitic framework. The membrane developed in this work, a compact Na(+)-exchanged ZSM-5 (NaZSM-5) type zeolite membrane. enables us to selectively permeate and separate bigger polar molecules, such as methanol and water, from a stream containing hydrogen, above 473 K. On the other hand, a Na(+)-free, H(+)-exchanged ZSM-5 (HZSM-5) type zeolite membrane did not show separation properties at these temperatures. The microporous zeolite membrane developed in this study can be applied to a variety of chemical reaction systems to minimize energy consumption.

The water gas shift (WGS) reaction over Pt and Pd catalysts supported on various perovskite oxides has been investigated at 573 K without catalyst pretreatment. The Pt and Pd catalysts on LaCoO(3) support showed high catalytic activity. Interaction between Pt or Pd and the support is considered to promote the WGS reaction: Pt/LaCoO(3) had high initial activity but deactivated immediately: Pd/LaCoO(3) was less active than Pt/LaCoO(3), but had superior stability. Catalysts were characterized using XRD, STEM, XPS, and H(2)-temperature programmed reduction (TPR). Results of this study showed that reduction of the support decreased the CO conversion on Pt/LaCoO(3). On the other hand, Pd/LaCoO(3) showed stable activity for the WGS reaction. Therefore, Pd was added to Pt/LaCoO(3) for stabilizing the catalyst activity, and 0.5 wt.% Pd/1 wt.% Pt/LaCoO(3) catalyst showed higher activity and stability. (C) 2008 Elsevier B.V. All rights reserved.

Various La2O3-based catalysts are well-known to be useful for the oxidative coupling of methane (OCM reaction). We examined the catalytic activities of various La2O3-based OCM catalysts for the OCM reaction in the kinetic region (i.e., lower O-2 conversion). Our investigation revealed that the Fe-doped La2O3 catalyst is a good candidate for the OCM reaction. The La/Fe ratio of the Fe-doped La2O3 catalyst is an important factor for OCM activity. Especially, the O-2-based C-2 yield of the Fe-doped La2O3 catalyst was higher than that of La2O3 in the case of La/Fe > 5. The Fe-doped La2O3 catalyst modified with Na2O and Na4P2O7 showed high C-2 Selectivity (83%). Moreover, modification with Bi compounds also enhanced C-2 selectivity of the Fe-doped La2O3 catalyst. This catalyst showed higher C-2 yield than the Fe-doped La2O3 catalyst.

Styrene is manufactured industrially through catalytic dehydrogenation of ethylbenzene on Fe-K oxide-based catalysts. It was invented by Sud-Chemie Group that the activity of the industrial ethylbenzene dehydrogenation catalysts (Styromax) based on the oxides of Fe and K is highly promoted by the addition of small amount (hundreds ppm-order) of precious metals such as Pd. The present work is intended to elucidate the role of Pd on the Fe-K catalyst empirically by use of a periodical pulse technique from a mechanistic point of view. The oxidative dehydrogenation was faster than the simple dehydrogenation, and it proceeded by consuming the surface lattice oxygen in the catalyst. The lattice oxygen was subsequently supplied from steam. Palladium added to the Fe-K oxide catalysts was found to enhance the rate of regeneration (supplying) of the lattice oxygen, although it hardly changed the rate of dehydrogenation of ethylbenzene or consumption of surface lattice O(2-) anions. This study demonstrated that steam works not only as a diluent but also as a reactant to form hydrogen and lattice oxygen.

A mordenite membrane was prepared on the outer surface of a porous a-alumina tubular support by a secondary-growth method. Permeation tests for water/methanol/hydrogen mixtures were performed at 423 and 473 K. A mordenite membrane free from non-zeolitic pores allowed us selective permeation of steam and blocked the permeation of hydrogen and methanol. In order to elucidate the mechanism of such selective permeation behavior, adsorption, permeation, and structural properties of the mordenite membrane were discussed. As a result, it was considered that selective permeation of steam against hydrogen was based on its preferential adsorption of steam, while boundaries between mordenite crystals in the membrane may play a key role for inhibiting the permeation of methanol.

Controlling the growth of zeolite crystals on a porous alumina support is essential for preparing a compact zeolite membarne. First, mordenite seed crystals applied on a nonporous a-alumina disk were grown and morphological change of mordenite crystals were observed in the course of growth. Then, mordenite membranes were synthesized on a porous a-alumina tube under the same conditions employed in the study using the alumina disks. We found that seed crystal growth was widely controllable by changing water content in reaction solution, which resulted in better control of the morphology of mordenite crystals for synthesizing a thin compact mordenite membrane. Separation properties for mordenite membranes were studied in water-hydrogen binary system at 473 K with 10 kPa of water partial pressure, where no capillary condensation was expected in non-zeolitic pores. Separation factor for a mordenite membrane with a few defects was poor; however, a defect-free mordenite membrane prepared under a suitable condition highly separated steam from hydrogen. (C) 2007 Elsevier B.V. All rights reserved.

The steam reforming of ethanol was performed over Co and Ni catalysts supported on perovskite-type oxides (LaAlO3, SrTiO3 and BaTiO3). Co and Ni catalysts supported on LaAlO3 and SrTiO3 showed high catalytic activities and long-term stabilities and suppressed coke formation while Co/BaTiO3 showed lower catalytic activities and poorer coking resistance. The average particle size of Co oil BaTiO3 was larger than that on SrTiO3. Lattice oxygen in perovskites may play positive roles in hindering coking and Co/SrTiO3 has more frequent participation of lattice oxygen in the oxidation of intermediates or precursor of coke in comparison with Co/BaTiO3. (c) 2007 Elsevier B.V. All rights reserved.

The steam reforming of ethanol for producing hydrogen was evaluated over 5 wt% Co catalysts supported on perovskite-type oxides, La1-xSrxBO3 (B = Al, Cr, Mn, Fe, x = 0-0.2) at 823 K with a molar H2O/C2H5OH ratio of 6. Co/LaAlO3 showed higher catalytic activity and stability than Co catalysts supported on LaCrO3, LaFeO3 and LaMnO3. The molar La/Al ratio markedly affected the stability of Co/LaAlO3 catalyst and a molar La/Al ratio of I was the most suitable, suggesting that the properties of the perovskite structure are important in the catalytic activity and stability. Partial substitution of Sr2+ for La 31 in LaAlO3 resulted in further remarkable improvement of catalytic activity and hydrogen yield. We consider that enhanced mobility of lattice oxygen in La1-xSrxAlO3-delta allows more frequent participation in the oxidation of intermediates over metallic cobalt, leading to both high catalytic activity and stability of Co/La1-xSrxAlO3-delta,5 in comparison with Co/LaAlO3.

Separation properties of a mordenite membrane for water-methanol-hydrogen mixtures were studied in the temperature range from 423 to 523 K under pressurized conditions. The mordenite membrane was prepared on the outer surface of a porous alumina tubular support by a secondary-growth method. It was found that water was selectively permeated through the membrane. The separation factor of water/hydrogen and water/methanol were 49-156 and 73-101, respectively. Even when only hydrogen was fed at 0.5 MPa, its permeance was as low as 10(-9) mol m(-2) s(-1) Pa-1 up to 493 K, possibly suggesting that water pre-adsorbed in the micropores of mordenite hindered the permeation of hydrogen. The hydrogen permeance dramatically increased to 6.5 x 10(-7) mol m(-2) s(-1) Pa-1 at 503 K and reached to 1.4 x 10(-6) mol m(-2) s(-1) Pa-1 at 523 K because of the formation of cracks in the membrane. However, the membrane was thermally stabilized in the presence of steam and/or methanol. (C) 2007 Elsevier B.V. All rights reserved.

High-temperature coal utilization processes (combustion, gasification and pyrolysis) emit toxic trace elements into the atmosphere, where they affect the environment and human health. We carried out coal combustion and gasification experiments using several kinds of coals at various temperatures and atmospheric conditions to examine the release behavior of trace elements. Results showed that Group 1 and 2 metals such as Fig, Se, Sb, and Zn were partly released from coal during combustion, gasification and pyrolysis. Oxygen or steam in the operating atmosphere affected the behavior of Fig, Se, Sb, and Zn release from coal. (C) 2007 Elsevier B.V. All rights reserved.

Tubular FAU-type zeolite membrane was synthesized on porous alumina substrate with 80 cm long by a seeded growth method. Pervaporation experiments using a mixture of water (10 wt%)/ethanol (90 wt%) at 75 degrees C demonstrated superior permeation properties of this type of membrane showing the total flux of 4-10 (kg m(-2) h(-1)) with the separation factor of 110-300. A part of the synthesized membrane with 10 cm long was applied to gas separation at high pressures of 1-5 MPa and high temperatures of 130 and 180 degrees C. Ternary mixtures of water, methanol and hydrogen were used for evaluating the permselectivities of FAU-type membrane. It was found that hydrogen permeation was strongly depressed in the presence of water and methanol. Preferential adsorption of water and methanol in the micropores of FAU-type zeolite possibly played an important role for the appearance of permselectivity. (c) 2006 Elsevier Inc. All rights reserved.

We investigated the alkylation of toluene with methanol at 250 degrees C over MCM-22 and ITQ-2 zeolites possessing an MWW structure. Whereas ITQ-2, produced by the delamination of MCM-22 precursor, showed a poor p-xylene selectivity of 23% at 1.7% of the level of toluene conversion, a high p-xylene selectivity of 80% at 0.6% of the level of toluene conversion was obtained by poisoning the external surface of ITQ-2 with collidine. Similarly, MCM-22 treated with collidine showed a high p-xylene selectivity of 74% at 3.8% of the level of toluene conversion. We concluded that both interlayer and intralayer 10-membered ring (10MR) micropores in the MWW structure caused the shape-selective formation of p-xylene in the alkylation of toluene with methanol. (c) 2006 Elsevier B.V. All rights reserved.

We investigated the alkylation of toluene with methanol at 250 degrees C over MCM-22 and ITQ-2 zeolites possessing an MWW structure. Whereas ITQ-2, produced by the delamination of MCM-22 precursor, showed a poor p-xylene selectivity of 23% at 1.7% of the level of toluene conversion, a high p-xylene selectivity of 80% at 0.6% of the level of toluene conversion was obtained by poisoning the external surface of ITQ-2 with collidine. Similarly, MCM-22 treated with collidine showed a high p-xylene selectivity of 74% at 3.8% of the level of toluene conversion. We concluded that both interlayer and intralayer 10-membered ring (10MR) micropores in the MWW structure caused the shape-selective formation of p-xylene in the alkylation of toluene with methanol. (c) 2006 Elsevier B.V. All rights reserved.

Novel catalytic reaction with high voltage electric field was conducted with a pyloritic reaction of ethanol as a model reaction. As a catalyst, Pt was supported on some of oxides, and high voltage electric field was applied on the catalyst. Pt supported ceria catalyst showed very high activity among these catalysts at lower temperature as 300 degree centigrade. Compare to conventional catalytic process, this novel system can be achieved at lower temperature with a high energy efficiency.

On the steam reforming of methane, coke formation on the catalyst was severe problem which causes the deactivation of catalyst. So, suppressing the coke formation was expected for the fuel cell application. Up to now, we employed perovskite oxides as a support of catalyst which has mobile oxygen on/in the support, and conducted redox type steam reforming reaction with this catalyst. In this presentation, we tried to examine the effect of support on this reforming reaction.

Biogas is one of important energy which could be obtained from the anaerobic fermentation of organic materials. There are several problems in the catalytic reforming of biomethane due to the higher concentration of H2S in biogas. Therefore, we examined direct reforming of biogas at ambient temperature, atmospheric pressure without catalyst by electric discharge (esp. LEP, DBD), and influence of type of discharge on the chemical reactions in this study.

Tetraethylammonium (TEA(+))-containing silicate dry gels exhibiting a maximum in the reflection peak at 2 theta = 28 degrees in an XRD pattern using Cu K alpha radiation are always transformed into *BEA-type zeolite with steam-assisted crystallization.

Tetraethylammonium (TEA(+))-containing silicate dry gels exhibiting a maximum in the reflection peak at 2 theta = 28 degrees in an XRD pattern using Cu K alpha radiation are always transformed into *BEA-type zeolite with steam-assisted crystallization.

A novel organic-inorganic hybrid mesoporous iron oxophenyl phosphate has been synthesized by using supramolecular assembly of sodium dodecyl sulfate molecules. X-ray diffraction, transmission electron microscopic studies, and N-2 adsorption data indicated the wormhole-like disordered mesostructure in this sample. The C-13 and P-31 MAS NMR, FT IR, UV-visible spectroscopic data, and chemical analysis results indicated that all P atoms are attached to phenyl groups directly and combined with Fe atoms through O atoms. Calcination of this hybrid material produced organic-free mesoporous iron oxophosphate material, whereas sulfonation of the mesoporous iron oxophenyl phosphate resulted in sulfonated oxophenyl phosphate. The latter showed outstanding proton conductivity, which could be utilized in membrane or supports of anode and cathode materials in fuel cells.

A novel organic-inorganic hybrid mesoporous iron oxophenyl phosphate has been synthesized by using supramolecular assembly of sodium dodecyl sulfate molecules. X-ray diffraction, transmission electron microscopic studies, and N-2 adsorption data indicated the wormhole-like disordered mesostructure in this sample. The C-13 and P-31 MAS NMR, FT IR, UV-visible spectroscopic data, and chemical analysis results indicated that all P atoms are attached to phenyl groups directly and combined with Fe atoms through O atoms. Calcination of this hybrid material produced organic-free mesoporous iron oxophosphate material, whereas sulfonation of the mesoporous iron oxophenyl phosphate resulted in sulfonated oxophenyl phosphate. The latter showed outstanding proton conductivity, which could be utilized in membrane or supports of anode and cathode materials in fuel cells.

Ferrierite zeolite membranes were prepared for the first time in the absence of organic structure-directing agents (SDA) on the surface of a porous a-alumina support. These membranes were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and pervaporation tests.

A novel organic-inorganic hybrid mesoporous niobium oxophenylphosphate was synthesized by using supramolecular assembly of sodium dodecylsulfate molecules. X-ray diffraction, transmission electron microscopic image and NZ adsorption data indicated the formation of a wormhole-like disordered mesostructure in the sample. The C-13 and P-31 MAS NMR, FTIR, UV-visible spectroscopic data and chemical analysis results indicated that all P atoms are attached to phenyl groups directly and these are combined with Nb atoms through O atoms. Calcination of this hybrid material yielded an organic-free mesoporous niobium oxophosphate material. (c) 2006 Elsevier Inc. All rights reserved.

A novel organic-inorganic hybrid mesoporous niobium oxophenylphosphate was synthesized by using supramolecular assembly of sodium dodecylsulfate molecules. X-ray diffraction, transmission electron microscopic image and NZ adsorption data indicated the formation of a wormhole-like disordered mesostructure in the sample. The C-13 and P-31 MAS NMR, FTIR, UV-visible spectroscopic data and chemical analysis results indicated that all P atoms are attached to phenyl groups directly and these are combined with Nb atoms through O atoms. Calcination of this hybrid material yielded an organic-free mesoporous niobium oxophosphate material. (c) 2006 Elsevier Inc. All rights reserved.

This study is intended to clarify the relationship among the reactivity of coal char with steam, structural change in residual carbon, and ash behavior. Steam gasification of various coal chars and demineralized chars was carried out in a fixed-bed reactor. After gasification, the reacted char was analyzed using laser raman spectroscope (LRS), and scanning electron microscope, energy dispersive X-ray spectroscope (SEM/EDX) mapping. Results of SEM images and EDX-mappings revealed that novel parallel analysis of cross correlation between EDX-mapping and LRS-mapping was found to be very effective for the comprehensive evaluation of ash behavior and carbonaceous structure. As the gasification reaction proceeds, the reactivity of the char was varied; existence of Si and Al seemed to suffocate the char reactivity. (c) 2005 Elsevier Ltd. All rights reserved.

A disk-type SM0.4Ba0.6Co0.2Fe0.8O3 (- delta) perovskite-type mixed-conducting membrane was applied to a membrane reactor for the partial oxidation of methane to syngas (CO + H-2). The reaction was carried out using Rh (1 wt%)/MgO catalyst by feeding CH4 diluted with Ar. While CH4 conversion increased and CO selectivity slightly decreased with increasing temperature, a high level of CH4 conversion (90 %) and a high selectivity to CO (98 %) were observed at 1173 K. The oxygen flux was increased under the conditions for the catalytic partial oxidation of CH4 compared with that measured when Ar was fed to the permeation side. We investigated the reaction pathways in the membrane reactor using different membrane reactor configurations and different kinds of gas. In the membrane reactor without the catalyst, the oxygen flux was not improved even when CH4 was fed to the permeation side, whereas the oxygen flux was enhanced when CO or H-2 was fed. It is implied that the oxidation of CO and H-2 with the surface oxygen on the permeation side improves the oxygen flux through the membrane, and that CO2 and H2O react with CH4 by reforming reactions to form syngas. (c) 2005 Elsevier B.V. All rights reserved.

The steam reforming of ethanol over Co and Ni catalysts supported on SrTiO3 was carried out at 823 K and atmospheric pressure. It was found that Co/SrTiO3 showed a high catalytic activity and long-term stability and remarkably inhibited carbon deposition. Copyright © 2005 The Chemical Society of Japan.

The steam reforming of ethanol over Co and Ni catalysts supported on SrTiO3 was carried out at 823 K and atmospheric pressure. It was found that Co/SrTiO3 showed a high catalytic activity and long-term stability and remarkably inhibited carbon deposition. Copyright © 2005 The Chemical Society of Japan.

Disk-type SrFeCo0.50Ox, asymmetric membranes were prepared for high-temperature oxygen separation using both a previously reported solid state technique in which ethyl cellulose is introduced and then removed by calcination to produce a porous support layer and a modified technique in which carbon fiber is added to the ethyl cellulose. The oxygen permeabilities of the resulting SrFeCo0.50Ox asymmetric membranes were measured at 973-1173 K. The addition of carbon fiber to ethyl cellulose resulted in the improvement of gas diffusivity in the porous support layer, which increased the flux of oxygen through the modified asymmetric membrane. (c) 2005 Elsevier B.V. All rights reserved.

Steam reforming of methane for the purpose of hydrogen production was performed using nickel catalysts supported on a variety of perovskites, including LaAlO3, LaFeO3, SrTiO3, BaTiO3, La0.4Ba0.6Co0.2Fe0.8O3-delta, to compare the catalytic activity and resistance to coking of these catalysts to those of the conventional Ni/alpha-Al2O3 catalyst. Ni/LaAlO3 and Ni/SrTiO3 showed high catalytic activities among the Ni/perovskites and longer-term stabilities than the conventional catalyst. Temperature programmed oxidation of carbon deposited on used catalysts revealed that inactive carbon species detected on Ni/alpha-Al2O3 were not formed in the case of Ni/LaAlO3. The results of temperature programmed reduction confirmed that consumption and recovery of the lattice oxygen in perovskites occurred during the reaction, and that the reducibility of perovskites had a great impact on the steam reforming activity. The lattice oxygen in perovskites is considered to play important roles in promoting the oxidation of CH, fragments adsorbed on metallic nickel. (c) 2005 Published by Elsevier B.V.

Disk-type SrFeCo0.50Ox, asymmetric membranes were prepared for high-temperature oxygen separation using both a previously reported solid state technique in which ethyl cellulose is introduced and then removed by calcination to produce a porous support layer and a modified technique in which carbon fiber is added to the ethyl cellulose. The oxygen permeabilities of the resulting SrFeCo0.50Ox asymmetric membranes were measured at 973-1173 K. The addition of carbon fiber to ethyl cellulose resulted in the improvement of gas diffusivity in the porous support layer, which increased the flux of oxygen through the modified asymmetric membrane. (c) 2005 Elsevier B.V. All rights reserved.

Steam reforming of methane for the purpose of hydrogen production was performed using nickel catalysts supported on a variety of perovskites, including LaAlO3, LaFeO3, SrTiO3, BaTiO3, La0.4Ba0.6Co0.2Fe0.8O3-delta, to compare the catalytic activity and resistance to coking of these catalysts to those of the conventional Ni/alpha-Al2O3 catalyst. Ni/LaAlO3 and Ni/SrTiO3 showed high catalytic activities among the Ni/perovskites and longer-term stabilities than the conventional catalyst. Temperature programmed oxidation of carbon deposited on used catalysts revealed that inactive carbon species detected on Ni/alpha-Al2O3 were not formed in the case of Ni/LaAlO3. The results of temperature programmed reduction confirmed that consumption and recovery of the lattice oxygen in perovskites occurred during the reaction, and that the reducibility of perovskites had a great impact on the steam reforming activity. The lattice oxygen in perovskites is considered to play important roles in promoting the oxidation of CH, fragments adsorbed on metallic nickel. (c) 2005 Published by Elsevier B.V.

The undesired structural change of mordenite with Si/Al-2 = 15 during the ion exchange and during calcination from the sodium form into proton form, especially the dealumination after the calcination, was studied. The Si-29 NMR results clarified that calcination of the NH4-form mordenite with Si/Al-2 = 15 at > ca. 800 K, followed by the contact of proton-form sample with the atmosphere containing humidity, induced the dealumination. However, the samples carefully kept free from humidity after the heat treatment showed no dealumination or only a low degree of it. The Al-27 NMR and ammonia TPD results agreed with these findings. The origin of dealumination is thus considered to be the contact of the proton-form sample with humidity after the calcination. On the other hand, the dealumination was not observed after calcination at < 673 K. The H-1 NMR indicated that the ca. 1/3 of the ion-exchange sites were blocked by the ammonium cations after calcination at 673 K, suggesting that the dealumination was prevented by the ammonium cations. On the basis of these findings, a standard set of conditions in which one can safely prepare the proton-form zeolite with high quality is proposed. The recommended temperature for the ion exchange is room temperature, because it is high enough to exchange the ions in this case. The most important variable is the calcination temperature; it should be lower than 673 K in order to avoid the dealumination. These conditions were confirmed to yield zeolites with a high framework aluminum content and ordinary catalytic performance. (c) 2005 Elsevier B.V. All rights reserved.

A joint study was organized to establish a standard set of conditions for the ion exchange of zeolite from sodium into proton-form. The sodium-form mordenite with Si/Al-2 = ca. 15 was ion exchanged into an NH4-form, followed by calcination according to various recipes. Then various advanced techniques for characterization (ICP, TG, XPS, SEM, XRD, N-2 adsorption Si-29 and Al-27 NMR, benzene diffusion, IR of OH and adsorbed pyridine and CO, ammonia TPD) were applied. and some test reactions (cracking of cumene, isopropylation of biphenyl, oligomerization of propene and chichibabin condensation of acetaldehyde and ammonia into picoline) were conducted. The ion exchange (removal of sodium) proceeded as expected, but remarkable differences were observed in physicochemical and catalytic properties of the thus-prepared proton-form samples. Exceptionally high temperature (383 K) for the ion exchange resulted in the structural degradation, while most samples exchanged at 333-353 K maintained the crystallinity and pore volume. The use of NH4Cl slightly changed the crystal morphology. Extra-framework aluminum species was formed on most samples after calcination above 773 K. In contrast, calcination at 673 K maintained the framework aluminum. Therefore, the dealumination is considered to proceed after complete removal of ammonia from the ammonium-form zeolite. However, the proton-form zeolite was stable under dry conditions, so it is speculated that the dealumination was induced by the contact of the proton-form zeolite to atmosphere with humidity. The total and Bronsted acidity decreased with the dealumination, while Lewis acidity increased. On the other hand, rapid heating of the ammonium type zeolite caused narrowing of the micropores. These structural changes seriously affected the catalytic activities for various reactions. (c) 2005 Elsevier B.V. All rights reserved.

The undesired structural change of mordenite with Si/Al-2 = 15 during the ion exchange and during calcination from the sodium form into proton form, especially the dealumination after the calcination, was studied. The Si-29 NMR results clarified that calcination of the NH4-form mordenite with Si/Al-2 = 15 at > ca. 800 K, followed by the contact of proton-form sample with the atmosphere containing humidity, induced the dealumination. However, the samples carefully kept free from humidity after the heat treatment showed no dealumination or only a low degree of it. The Al-27 NMR and ammonia TPD results agreed with these findings. The origin of dealumination is thus considered to be the contact of the proton-form sample with humidity after the calcination. On the other hand, the dealumination was not observed after calcination at < 673 K. The H-1 NMR indicated that the ca. 1/3 of the ion-exchange sites were blocked by the ammonium cations after calcination at 673 K, suggesting that the dealumination was prevented by the ammonium cations. On the basis of these findings, a standard set of conditions in which one can safely prepare the proton-form zeolite with high quality is proposed. The recommended temperature for the ion exchange is room temperature, because it is high enough to exchange the ions in this case. The most important variable is the calcination temperature; it should be lower than 673 K in order to avoid the dealumination. These conditions were confirmed to yield zeolites with a high framework aluminum content and ordinary catalytic performance. (c) 2005 Elsevier B.V. All rights reserved.

A joint study was organized to establish a standard set of conditions for the ion exchange of zeolite from sodium into proton-form. The sodium-form mordenite with Si/Al-2 = ca. 15 was ion exchanged into an NH4-form, followed by calcination according to various recipes. Then various advanced techniques for characterization (ICP, TG, XPS, SEM, XRD, N-2 adsorption Si-29 and Al-27 NMR, benzene diffusion, IR of OH and adsorbed pyridine and CO, ammonia TPD) were applied. and some test reactions (cracking of cumene, isopropylation of biphenyl, oligomerization of propene and chichibabin condensation of acetaldehyde and ammonia into picoline) were conducted. The ion exchange (removal of sodium) proceeded as expected, but remarkable differences were observed in physicochemical and catalytic properties of the thus-prepared proton-form samples. Exceptionally high temperature (383 K) for the ion exchange resulted in the structural degradation, while most samples exchanged at 333-353 K maintained the crystallinity and pore volume. The use of NH4Cl slightly changed the crystal morphology. Extra-framework aluminum species was formed on most samples after calcination above 773 K. In contrast, calcination at 673 K maintained the framework aluminum. Therefore, the dealumination is considered to proceed after complete removal of ammonia from the ammonium-form zeolite. However, the proton-form zeolite was stable under dry conditions, so it is speculated that the dealumination was induced by the contact of the proton-form zeolite to atmosphere with humidity. The total and Bronsted acidity decreased with the dealumination, while Lewis acidity increased. On the other hand, rapid heating of the ammonium type zeolite caused narrowing of the micropores. These structural changes seriously affected the catalytic activities for various reactions. (c) 2005 Elsevier B.V. All rights reserved.

Addition of an exceedingly small amount of zirconia onto iron oxide enhanced the activity for hydrogen production by the oxidation of partially reduced iron oxide. Sintering of iron oxide was also suppressed.

Synthesis of novel mesoporous hybrid tin oxophosphate is reported from phenylphosphonic acid as the only precursor of phosphorus in the presence of anionic surfactant (SDS), which possesses a wormhole mesoporous structure and is stable even after calcination at 550 degrees C.

Rapid synthesis of Si-MCM-41 was accomplished in successive two steps; (1) aging of a Mixture of silica, hexadecylammonium bromide and water with ail aqueous ammonia solution for a short period of 30 min, and (2) successive evaporation-to-dryness of the resultant mixture at 80 degrees C in about 2 h. The yield of Si-MCM-41 reached 99% after calcination at 550 degrees C. The product obtained by this method gave a well-ordered 2d-hexagonal structure with high thermal stability and water-resistance. It was noteworthy that the d(100) value of calcined Si-MCM-41 was almost the same as that of as-made Si-MCM-41, suggesting that pore wall of as-made product was dense and rigid.

The role of steam oil the crystallization of zeolite beta by the steam-assisted crystallization (SAC) method was studied. It was found that after an aluminosilicate dry gel with SiO2/Al2O3 molar ratio = 100 was treated with steam in an autoclave at 130 degrees C and autogenous pressure, thermal treatment of a resultant product at 130 degrees C without the addition of water in an autoclave gave zeolite beta with a high crystallinity. Zeolite beta obtained by this method consisted of nano-particles with a diameter of ca. 30 nm. It was presumed that intermediates of zeolite beta was formed during steam treatment, and the dehydration between silanols in the intermediates during the thermal treatment in the absence of steam possibly caused the transformation from ill-ordered structures to zeolite beta crystals with a periodicity in long-range order.

A preferentially oriented mordenite membrane was successfully prepared on a seeded porous α-alumina support. Characterization results of XRD (X-ray diffractometer) and FE-SEM (field emission scanning electron microscope) revealed that evolutionary selection might predominantly contribute to the formation of the sharply oriented mordenite membrane. The necessary conditions under which evolutionary selection occurs are: (a) the number density of nuclei on the support surface should be high enough at the early stage
(b) the crystals should grow fastest along one direction
and (c) the zeolite layer should proceed via the successive growth of the crystals nucleated on the support surface instead of the accumulation of the crystals formed in the bulk solution.

We demonstrated that non-catalytic ethanol steam reforming proceeds efficiently and selectively without coking at the conditions of room temperature and atmospheric pressure using low-energy pulsed (LEP) discharge in combination with carbon fiber electrodes.

Synthesis of novel mesoporous hybrid tin oxophosphate is reported from phenylphosphonic acid as the only precursor of phosphorus in the presence of anionic surfactant (SDS), which possesses a wormhole mesoporous structure and is stable even after calcination at 550 degrees C.

Rapid synthesis of Si-MCM-41 was accomplished in successive two steps; (1) aging of a Mixture of silica, hexadecylammonium bromide and water with ail aqueous ammonia solution for a short period of 30 min, and (2) successive evaporation-to-dryness of the resultant mixture at 80 degrees C in about 2 h. The yield of Si-MCM-41 reached 99% after calcination at 550 degrees C. The product obtained by this method gave a well-ordered 2d-hexagonal structure with high thermal stability and water-resistance. It was noteworthy that the d(100) value of calcined Si-MCM-41 was almost the same as that of as-made Si-MCM-41, suggesting that pore wall of as-made product was dense and rigid.

The role of steam oil the crystallization of zeolite beta by the steam-assisted crystallization (SAC) method was studied. It was found that after an aluminosilicate dry gel with SiO2/Al2O3 molar ratio = 100 was treated with steam in an autoclave at 130 degrees C and autogenous pressure, thermal treatment of a resultant product at 130 degrees C without the addition of water in an autoclave gave zeolite beta with a high crystallinity. Zeolite beta obtained by this method consisted of nano-particles with a diameter of ca. 30 nm. It was presumed that intermediates of zeolite beta was formed during steam treatment, and the dehydration between silanols in the intermediates during the thermal treatment in the absence of steam possibly caused the transformation from ill-ordered structures to zeolite beta crystals with a periodicity in long-range order.

A preferentially oriented mordenite membrane was successfully prepared on a seeded porous α-alumina support. Characterization results of XRD (X-ray diffractometer) and FE-SEM (field emission scanning electron microscope) revealed that evolutionary selection might predominantly contribute to the formation of the sharply oriented mordenite membrane. The necessary conditions under which evolutionary selection occurs are: (a) the number density of nuclei on the support surface should be high enough at the early stage
(b) the crystals should grow fastest along one direction
and (c) the zeolite layer should proceed via the successive growth of the crystals nucleated on the support surface instead of the accumulation of the crystals formed in the bulk solution.

We demonstrated that non-catalytic ethanol steam reforming proceeds efficiently and selectively without coking at the conditions of room temperature and atmospheric pressure using low-energy pulsed (LEP) discharge in combination with carbon fiber electrodes.

Fuel cell is attracting attention, especially polymer electrolyte membrane fuel cell. However, hydrogen production and transportation processes have many problems with the present technology so innovative technological methods to produce hydrogen are needed. Low energy pulse discharge was used for this goal. The energy efficiency was improved because the liquid phase reactor did not require a heater which is needed to vaporize the mixture of water and ethanol. Any pump supplying the liquid into the reactor was not required. So the liquid phase reactor made the process scale reduced, and also made the device size compact without spoiling its function. This process would be very useful for room temperature hydrogen formation system.

MCM-41-type mesoporous materials possessing strong Bronsted acidity originated from ZSM-5 zeolite were synthesized by using soluble aluminosilicate species containing the fragments of the structure of ZSM-5 zeolite. The thermal stability of the mesoporous structure of the obtained mesoporous material was enhanced by the post-treatment with an ammonium aqueous solution. These results suggest an important role of alkalinity of slurries on the following two processes; (1) alkaline dissolution of ZSM-5 zeolite and (2) formation of mesoporous structure. These successive processes were efficiently improved by use of a continuous-flow reactor. The mesoporous material synthesized in the continuous-flow reactor catalyzed the cracking of cumene at 523 K, while a conventional Al-MCM-41 hardly catalyzed. The mesoporous material synthesized by using the filtrate of alkaline dissolution of ZSM-5 possessed a stronger Bronsted acidity than a conventional Al-MCM-41. (C) 2004 Elsevier Inc. All rights reserved.

MCM-41-type mesoporous materials possessing strong Bronsted acidity originated from ZSM-5 zeolite were synthesized by using soluble aluminosilicate species containing the fragments of the structure of ZSM-5 zeolite. The thermal stability of the mesoporous structure of the obtained mesoporous material was enhanced by the post-treatment with an ammonium aqueous solution. These results suggest an important role of alkalinity of slurries on the following two processes; (1) alkaline dissolution of ZSM-5 zeolite and (2) formation of mesoporous structure. These successive processes were efficiently improved by use of a continuous-flow reactor. The mesoporous material synthesized in the continuous-flow reactor catalyzed the cracking of cumene at 523 K, while a conventional Al-MCM-41 hardly catalyzed. The mesoporous material synthesized by using the filtrate of alkaline dissolution of ZSM-5 possessed a stronger Bronsted acidity than a conventional Al-MCM-41. (C) 2004 Elsevier Inc. All rights reserved.

MCM-41-type mesoporous materials possessing strong Bronsted acidity originated from ZSM-5 zeolite were synthesized by using soluble aluminosilicate species containing the fragments of the structure of ZSM-5 zeolite. The thermal stability of the mesoporous structure of the obtained mesoporous material was enhanced by the post-treatment with an ammonium aqueous solution. These results suggest an important role of alkalinity of slurries on the following two processes; (1) alkaline dissolution of ZSM-5 zeolite and (2) formation of mesoporous structure. These successive processes were efficiently improved by use of a continuous-flow reactor. The mesoporous material synthesized in the continuous-flow reactor catalyzed the cracking of cumene at 523 K, while a conventional Al-MCM-41 hardly catalyzed. The mesoporous material synthesized by using the filtrate of alkaline dissolution of ZSM-5 possessed a stronger Bronsted acidity than a conventional Al-MCM-41. (C) 2004 Elsevier Inc. All rights reserved.

MCM-22 zeolite crystallized by the vapor-phase transport (VPT) method showed a higher shape-selectivity to p-xylene in the alkylation of toluene with methanol, compared with MCM-22 crystallized by the hydrothermally synthetic (HTS) method, because VPT-MCM-22 has a smaller external surface area and a smaller number of acid sites thereon than HTS-MCM-22. Such textural properties of VPT-MCM-22 are caused by the fact that the spherical particles of VPT-MCM-22 are composed of hexagonal plates as thin as 55 nm; they are larger than those of HTS-MCM-22, which are 30 nm thick. The acidic properties, characterized by NH3-TPD and FT-IR using a pyridine adsorption technique, showed no significant difference between VPT- and HTS-MCM-22, except for the acidity on the external surface.

MCM-22 zeolite crystallized by the vapor-phase transport (VPT) method showed a higher shape-selectivity to p-xylene in the alkylation of toluene with methanol, compared with MCM-22 crystallized by the hydrothermally synthetic (HTS) method, because VPT-MCM-22 has a smaller external surface area and a smaller number of acid sites thereon than HTS-MCM-22. Such textural properties of VPT-MCM-22 are caused by the fact that the spherical particles of VPT-MCM-22 are composed of hexagonal plates as thin as 55 nm; they are larger than those of HTS-MCM-22, which are 30 nm thick. The acidic properties, characterized by NH3-TPD and FT-IR using a pyridine adsorption technique, showed no significant difference between VPT- and HTS-MCM-22, except for the acidity on the external surface.

Zeolite membrane has been fabricated on porous alumina substrate in a single continuous process of gelation and subsequent crystallization while suppressing nucleation of zeolite powder in the bulk.

Zeolite membrane has been fabricated on porous alumina substrate in a single continuous process of gelation and subsequent crystallization while suppressing nucleation of zeolite powder in the bulk.

Steam reforming of methane, propane, hexane, cyclohexane, methanol, and ethanol using a nonequilibrium pulsed discharge was investigated under the conditions of atmospheric pressure and low temperature (393 K) without the use of catalyst. In each case, steam reforming proceeded efficiently and selectively and hydrogen was formed as a main product. Although the steam/ carbon ratio was 1, there were trace amounts of carbon deposition or wax formation. The energy injection for the discharge region calculated by current and voltage waveforms measured by a digital signal oscilloscope was very small. As compared with the conventional catalytic steam reforming process, this method has some advantages such as fast start-up, quick response, and miniaturization and simplification of a hydrogen production system. Therefore we consider that the hydrogen production system employing a nonequilibrium pulsed discharge has a potential for being an effective way for supplying hydrogen or syngas.

Microporous layered zirconium phenylphosphonate, Zr(O3P-C6H5)(2) was prepared in presence of sodium dodecylsulfate (SDS), for the first time. Interplanar spacing (d(001)) and surface area of microporous zirconium phenylphosphonate are 1.47 nm and 198 m(2)g(-1), respectively. FT-IR spectrum indicates absence or negligible amount of hydroxyls groups ill zirconium phenylphosphonate sample. P-31 solid MAS NMR also confirms the presence of trace amount of hydroxyl groups in zirconium phenylphosphonate. The presence of tetra-coordinated phosphorous ions and hexa-coordinated zirconium ions were realized by the P-31 solid MAS NMR and UV-visible, respectively. Sulfonated derivative of zirconium phenylphosphonate, Zr(O3PC6H4SO3H)(1.9) (O3PC6H5)(0.1)center dot 3.7H(2)O were also prepared.

The catalytic behavior of Pt supported on non-acidic silicalite-1 (MFI structure) and on the stannosilicate, Sn-sil-1 molecular sieves in the aromatization of n-hexane is investigated. The influence of Pt content, temperature, space velocity, H-2/n-hexane ratio and time on stream (TOS) on the n-hexane conversion, aromatic selectivity and aromatic yield are presented. Aromatics are the main products and this suggests that the aromatization proceeds via dehydrocyclization and/or hydrogenolysis, dehydrogenation to C-2-C-4 olefins followed by oligomerization inside the pores of the molecular sieve into cyclic intermediates in presence of hydrogen. The incorporation of Pt during the synthesis of the stannosilicate (Sn-sil-1) yields a more active catalyst (42 wt% aromatic selectivity) without any deactivation than when Pt is loaded by impregnation on Sn-sil-1 because catalyst deactivation associate with platinum outside the zeolite pores. A formation mechanism is proposed.

A new method of modification of TS-1 by weak base (aqueous NH3) treatment leads to formation of bigger crystals and generation of internal hydroxyl groups as evident by SEM and IR (hydroxyl region). All the catalysts were characterized using, XRD, N-2-sorption, UV-VIS, FT-IR and SEM. Activity of the modified and unmodified TS-1 were compare in the hydroxylation of phenol to hydroquinone and catechol in presence of aqueous H2O2. A ratio of hydroquinone to catechol over modified,(TS-1 (33)/OH1 and unmodified, TS-1(33) catalysts were 1.40 and 1.15, respectively, using H2O as solvent, and 2.01 and 1.68, respectively, using MeOH as solvent. Modification of TS-1 with strong base (e.g. NaOH) causes decrease in crystallinity, and hence decreases the conversion of phenol and selectivity of hydroquinone. A new mechanism controlling the product selectivity is proposed.

Compact ZSM-5 zeolite membranes have been prepared on the outer surface of a porous alpha-alumina tub without structure-directing agents (SDAs) by the seed-assisted crystallization method. An SDA-free gel and an SDA-free clear solution were used for the membrane preparation, respectively. ZSM-5 membrane prepared from the SDA-free gel showed the H-2/i-C4H10 ideal selectivity of 13.8 at 200 degrees C, but it decreased to be 2.1 after the pretreatment at 300 degrees C, indicating the limited thermal stability of this kind of ZSM-5 membrane. On the other hand, ZSM-5 membranes prepared from the SDA-free clear solution showed high thermal stability and good separation properties. After the pretreatment at 400 degrees C, the H-2/i-C4H10 idea selectivity was as high as 61 at 270 degrees C. The maximum of the n/i-C4H10 ideal selectivity was 36 at 300 degrees C and the separation factor was as high as 12.7 at 400 degrees C for a 50/50 n/i-C4H10 mixture.

Microporous layered zirconium phenylphosphonate, Zr(O3P-C6H5)(2) was prepared in presence of sodium dodecylsulfate (SDS), for the first time. Interplanar spacing (d(001)) and surface area of microporous zirconium phenylphosphonate are 1.47 nm and 198 m(2)g(-1), respectively. FT-IR spectrum indicates absence or negligible amount of hydroxyls groups ill zirconium phenylphosphonate sample. P-31 solid MAS NMR also confirms the presence of trace amount of hydroxyl groups in zirconium phenylphosphonate. The presence of tetra-coordinated phosphorous ions and hexa-coordinated zirconium ions were realized by the P-31 solid MAS NMR and UV-visible, respectively. Sulfonated derivative of zirconium phenylphosphonate, Zr(O3PC6H4SO3H)(1.9) (O3PC6H5)(0.1)center dot 3.7H(2)O were also prepared.

The catalytic behavior of Pt supported on non-acidic silicalite-1 (MFI structure) and on the stannosilicate, Sn-sil-1 molecular sieves in the aromatization of n-hexane is investigated. The influence of Pt content, temperature, space velocity, H-2/n-hexane ratio and time on stream (TOS) on the n-hexane conversion, aromatic selectivity and aromatic yield are presented. Aromatics are the main products and this suggests that the aromatization proceeds via dehydrocyclization and/or hydrogenolysis, dehydrogenation to C-2-C-4 olefins followed by oligomerization inside the pores of the molecular sieve into cyclic intermediates in presence of hydrogen. The incorporation of Pt during the synthesis of the stannosilicate (Sn-sil-1) yields a more active catalyst (42 wt% aromatic selectivity) without any deactivation than when Pt is loaded by impregnation on Sn-sil-1 because catalyst deactivation associate with platinum outside the zeolite pores. A formation mechanism is proposed.

A new method of modification of TS-1 by weak base (aqueous NH3) treatment leads to formation of bigger crystals and generation of internal hydroxyl groups as evident by SEM and IR (hydroxyl region). All the catalysts were characterized using, XRD, N-2-sorption, UV-VIS, FT-IR and SEM. Activity of the modified and unmodified TS-1 were compare in the hydroxylation of phenol to hydroquinone and catechol in presence of aqueous H2O2. A ratio of hydroquinone to catechol over modified,(TS-1 (33)/OH1 and unmodified, TS-1(33) catalysts were 1.40 and 1.15, respectively, using H2O as solvent, and 2.01 and 1.68, respectively, using MeOH as solvent. Modification of TS-1 with strong base (e.g. NaOH) causes decrease in crystallinity, and hence decreases the conversion of phenol and selectivity of hydroquinone. A new mechanism controlling the product selectivity is proposed.

Compact ZSM-5 zeolite membranes have been prepared on the outer surface of a porous alpha-alumina tub without structure-directing agents (SDAs) by the seed-assisted crystallization method. An SDA-free gel and an SDA-free clear solution were used for the membrane preparation, respectively. ZSM-5 membrane prepared from the SDA-free gel showed the H-2/i-C4H10 ideal selectivity of 13.8 at 200 degrees C, but it decreased to be 2.1 after the pretreatment at 300 degrees C, indicating the limited thermal stability of this kind of ZSM-5 membrane. On the other hand, ZSM-5 membranes prepared from the SDA-free clear solution showed high thermal stability and good separation properties. After the pretreatment at 400 degrees C, the H-2/i-C4H10 idea selectivity was as high as 61 at 270 degrees C. The maximum of the n/i-C4H10 ideal selectivity was 36 at 300 degrees C and the separation factor was as high as 12.7 at 400 degrees C for a 50/50 n/i-C4H10 mixture.

Microporous layered zirconium phenylphosphonate, Zr(O3P-C6H5)(2) was prepared in presence of sodium dodecylsulfate (SDS), for the first time. Interplanar spacing (d(001)) and surface area of microporous zirconium phenylphosphonate are 1.47 nm and 198 m(2)g(-1), respectively. FT-IR spectrum indicates absence or negligible amount of hydroxyls groups ill zirconium phenylphosphonate sample. P-31 solid MAS NMR also confirms the presence of trace amount of hydroxyl groups in zirconium phenylphosphonate. The presence of tetra-coordinated phosphorous ions and hexa-coordinated zirconium ions were realized by the P-31 solid MAS NMR and UV-visible, respectively. Sulfonated derivative of zirconium phenylphosphonate, Zr(O3PC6H4SO3H)(1.9) (O3PC6H5)(0.1)center dot 3.7H(2)O were also prepared.

The catalytic behavior of Pt supported on non-acidic silicalite-1 (MFI structure) and on the stannosilicate, Sn-sil-1 molecular sieves in the aromatization of n-hexane is investigated. The influence of Pt content, temperature, space velocity, H-2/n-hexane ratio and time on stream (TOS) on the n-hexane conversion, aromatic selectivity and aromatic yield are presented. Aromatics are the main products and this suggests that the aromatization proceeds via dehydrocyclization and/or hydrogenolysis, dehydrogenation to C-2-C-4 olefins followed by oligomerization inside the pores of the molecular sieve into cyclic intermediates in presence of hydrogen. The incorporation of Pt during the synthesis of the stannosilicate (Sn-sil-1) yields a more active catalyst (42 wt% aromatic selectivity) without any deactivation than when Pt is loaded by impregnation on Sn-sil-1 because catalyst deactivation associate with platinum outside the zeolite pores. A formation mechanism is proposed.

A new method of modification of TS-1 by weak base (aqueous NH3) treatment leads to formation of bigger crystals and generation of internal hydroxyl groups as evident by SEM and IR (hydroxyl region). All the catalysts were characterized using, XRD, N-2-sorption, UV-VIS, FT-IR and SEM. Activity of the modified and unmodified TS-1 were compare in the hydroxylation of phenol to hydroquinone and catechol in presence of aqueous H2O2. A ratio of hydroquinone to catechol over modified,(TS-1 (33)/OH1 and unmodified, TS-1(33) catalysts were 1.40 and 1.15, respectively, using H2O as solvent, and 2.01 and 1.68, respectively, using MeOH as solvent. Modification of TS-1 with strong base (e.g. NaOH) causes decrease in crystallinity, and hence decreases the conversion of phenol and selectivity of hydroquinone. A new mechanism controlling the product selectivity is proposed.

Compact ZSM-5 zeolite membranes have been prepared on the outer surface of a porous alpha-alumina tub without structure-directing agents (SDAs) by the seed-assisted crystallization method. An SDA-free gel and an SDA-free clear solution were used for the membrane preparation, respectively. ZSM-5 membrane prepared from the SDA-free gel showed the H-2/i-C4H10 ideal selectivity of 13.8 at 200 degrees C, but it decreased to be 2.1 after the pretreatment at 300 degrees C, indicating the limited thermal stability of this kind of ZSM-5 membrane. On the other hand, ZSM-5 membranes prepared from the SDA-free clear solution showed high thermal stability and good separation properties. After the pretreatment at 400 degrees C, the H-2/i-C4H10 idea selectivity was as high as 61 at 270 degrees C. The maximum of the n/i-C4H10 ideal selectivity was 36 at 300 degrees C and the separation factor was as high as 12.7 at 400 degrees C for a 50/50 n/i-C4H10 mixture.

Microporous layered zirconium phenylphosphonate, Zr(O3P-C6H5)(2) was prepared in presence of sodium dodecylsulfate (SDS), for the first time. Interplanar spacing (d(001)) and surface area of microporous zirconium phenylphosphonate are 1.47 nm and 198 m(2)g(-1), respectively. FT-IR spectrum indicates absence or negligible amount of hydroxyls groups ill zirconium phenylphosphonate sample. P-31 solid MAS NMR also confirms the presence of trace amount of hydroxyl groups in zirconium phenylphosphonate. The presence of tetra-coordinated phosphorous ions and hexa-coordinated zirconium ions were realized by the P-31 solid MAS NMR and UV-visible, respectively. Sulfonated derivative of zirconium phenylphosphonate, Zr(O3PC6H4SO3H)(1.9) (O3PC6H5)(0.1)center dot 3.7H(2)O were also prepared.

The catalytic behavior of Pt supported on non-acidic silicalite-1 (MFI structure) and on the stannosilicate, Sn-sil-1 molecular sieves in the aromatization of n-hexane is investigated. The influence of Pt content, temperature, space velocity, H-2/n-hexane ratio and time on stream (TOS) on the n-hexane conversion, aromatic selectivity and aromatic yield are presented. Aromatics are the main products and this suggests that the aromatization proceeds via dehydrocyclization and/or hydrogenolysis, dehydrogenation to C-2-C-4 olefins followed by oligomerization inside the pores of the molecular sieve into cyclic intermediates in presence of hydrogen. The incorporation of Pt during the synthesis of the stannosilicate (Sn-sil-1) yields a more active catalyst (42 wt% aromatic selectivity) without any deactivation than when Pt is loaded by impregnation on Sn-sil-1 because catalyst deactivation associate with platinum outside the zeolite pores. A formation mechanism is proposed.

A new method of modification of TS-1 by weak base (aqueous NH3) treatment leads to formation of bigger crystals and generation of internal hydroxyl groups as evident by SEM and IR (hydroxyl region). All the catalysts were characterized using, XRD, N-2-sorption, UV-VIS, FT-IR and SEM. Activity of the modified and unmodified TS-1 were compare in the hydroxylation of phenol to hydroquinone and catechol in presence of aqueous H2O2. A ratio of hydroquinone to catechol over modified,(TS-1 (33)/OH1 and unmodified, TS-1(33) catalysts were 1.40 and 1.15, respectively, using H2O as solvent, and 2.01 and 1.68, respectively, using MeOH as solvent. Modification of TS-1 with strong base (e.g. NaOH) causes decrease in crystallinity, and hence decreases the conversion of phenol and selectivity of hydroquinone. A new mechanism controlling the product selectivity is proposed.

Beta zeolite catalysts with different crystal sizes and similar acid strengths were synthesized in a "Steam-Assisted conversion (SAC)" technique. Pt loaded H-beta with an optimized crystal size of 600 nm showed high activity for hydrotreatment of tetralin by producing alkylbenzenes through area and low coke deposition. Isomerization reaction, which was expected to occur on the zeolite surface, was reduced considerably since tetralin interacted with strong Brönsted acid sites as soon as it penetrated the pore of the zeolite and underwent cracking to form linear hydrocarbons, C6 and C7 aromatics products. The method of supporting platinum on the zeolite had a significant effect on the activity of catalyst. For loading platinum of beta zeolite, ion exchange was a suitable method as it helped in well dispersion of platinum on the zeolite surface and inside the micropore.

Mordenite and ZSM-5 seeds could grow on the surface of an asymmetric α-Al2O3 support using an identical organic-free aluminosilicate solution under the same hydrothermal conditions. It suggests that the phase of zeolite can be controlled by varying the type of seed. Continuous mordenite and ZSM-5 membranes were prepared by the secondary growth method using corresponding seeds under appropriate conditions. The water content in the secondary growth mixture strongly influenced the growth of zeolite crystals. ZSM-5 seeds grew at a smaller rate and showed a habit of thin hexagonal plate in a concentrated mixture, while the crystals with a habit of rectangular parallelepiped were formed from a diluted secondary growth mixture. ZSM-5 crystals had poor intergrowth in the former case, whereas the crystals were highly intergrown in the latter case. ZSM-5 crystals in either membrane have a random orientation. In contrast to ZSM-5 zeolite, the crystal orientation in the secondary grown mordenite membranes strongly depended on the water content in the secondary growth mixture. The crystals in the mordenite membrane developed in a diluted secondary growth mixture were oriented with the (1 5 0) face parallel to the support surface, whereas the crystals in the membrane grown in a concentrated mixture were oriented with the (0 0 2) face parallel to the support surface. These results suggest that the crystal orientation in mordenite membranes can be manipulated only by changing the water content in a secondary growth mixture. The formation of the preferred crystal orientation in the secondary grown mordenite membrane is discussed in terms of an "evolutionary selection" process. © 2003 Elsevier Inc. All rights reserved.

A photoresponsive coumarin derivative was grafted on the pore outlet of Si-MCM-41. Irradiation of UV light longer than 310-nm wavelength to this coumarin-modified MCM-41 induced the photodimerization of coumarin to close the pore outlet with cyclobutane dimer. Guest molecules such as phenanthrene neither can enter nor escape from the one-dimensional, isolated, individual pores of MCM-41. On the other hand, the irradiation to the dimerized-coumarin-modified MCM-41 with shorter wavelength UV light around 250 nm regenerates the coumarin monomer derivative by the photocleavage of cyclobutane dimer, and guest molecules included inside are released from the pore void. For the first time, this intermolecular reversible photodimerization-cleavage cycle realized photo-switched storage and release of guest molecules from coumarin-modified MCM-41. Coumarin-modified MCM-41 prepared using tetradecyltrimethylammonium bromide as surfactant was able to store 21.6 wt % of phenanthrene as guest molecule after photodimerization and washing with n-hexane. Among the four different methods studied for the modification by the coumarin derivative, a grafting procedure with as-synthesized MCM-41 for short reaction time was found to be the most effective for the dense attachment of coumarin-derived monomer at the pore outlets of MCM-41, which is essential for effective storage-release controlled release.

Mordenite and ZSM-5 seeds could grow on the surface of an asymmetric alpha-Al2O3 support using an identical organic-free aluminosilicate solution under the same hydrothermal conditions. It suggests that the phase of zeolite can be controlled by varying the type of seed. Continuous mordenite and ZSM-5 membranes were prepared by the secondary growth method using corresponding seeds under appropriate conditions. The water content in the secondary growth mixture strongly influenced the growth of zeolite crystals. ZSM-5 seeds grew at a smaller rate and showed a habit of thin hexagonal plate in a concentrated mixture, while the crystals with a habit of rectangular parallelepiped were formed from a diluted secondary growth mixture. ZSM-5 crystals had poor intergrowth in the former case, whereas the crystals were highly intergrown in the latter case. ZSM-5 crystals in either membrane have a random orientation. In contrast to ZSM-5 zeolite, the crystal orientation in the secondary grown mordenite membranes strongly depended on the water content in the secondary growth mixture. The crystals in the mordenite membrane developed in a diluted secondary growth mixture were oriented with the (1 5 0) face parallel to the support surface, whereas the crystals in the membrane grown in a concentrated mixture were oriented with the (0 0 2) face parallel to the support surface. These results suggest that the crystal orientation in mordenite membranes can be manipulated only by changing the water content in a secondary growth mixture. The formation of the preferred crystal orientation in the secondary grown mordenite membrane is discussed in terms of an "evolutionary selection" process. (C) 2003 Elsevier Inc. All rights reserved.

A photoresponsive coumarin derivative was grafted on the pore outlet of Si-MCM-41. Irradiation of UV light longer than 310-nm wavelength to this coumarin-modified MCM-41 induced the photodimerization of coumarin to close the pore outlet with cyclobutane dimer. Guest molecules such as phenanthrene neither can enter nor escape from the one-dimensional, isolated, individual pores of MCM-41. On the other hand, the irradiation to the dimerized-coumarin-modified MCM-41 with shorter wavelength UV light around 250 nm regenerates the coumarin monomer derivative by the photocleavage of cyclobutane dimer, and guest molecules included inside are released from the pore void. For the first time, this intermolecular reversible photodimerization-cleavage cycle realized photo-switched storage and release of guest molecules from coumarin-modified MCM-41. Coumarin-modified MCM-41 prepared using tetradecyltrimethylammonium bromide as surfactant was able to store 21.6 wt % of phenanthrene as guest molecule after photodimerization and washing with n-hexane. Among the four different methods studied for the modification by the coumarin derivative, a grafting procedure with as-synthesized MCM-41 for short reaction time was found to be the most effective for the dense attachment of coumarin-derived monomer at the pore outlets of MCM-41, which is essential for effective storage-release controlled release.

It was investigated that the effects of preparation methods and conditions for SrFeCo0.5Ox dense membrane on their oxygen permeability. Three different methods, a solid-state reaction method, an evaporation-to-dryness method, and a combined citrate and EDTA complexing method, were applied for the preparation of parent powder. The oxygen flux through membrane at 900 degreesC was increased in the order listed above. The oxygen flux could be greatly improved by repeated calcination and grinding of parent powder. The membrane sintered at a temperature as high as 1200 degreesC showed a higher oxygen flux (0.22 cm(3) (STP)/cm(2) min). (C) 2003 Elsevier Science B.V. All rights reserved.

A study was carried out on the pervaporation of water from water-acetic acid mixtures through tubular ZSM-5 zeolite membranes. ZSM-5 zeolite membranes were prepared on the outer surface of a porous a-alumina tube by the seed-assisted crystallization method in the absence of organic templates. It was observed that water preferentially permeated with selectivities higher than the selectivity based on the vapor-liquid equilibrium in the entire range of acetic acid concentration. The separation mechanism of water through ZSM-5 zeolite membranes was discussed and compared with that through mordenite membranes. It was found that the permeability coefficients of both water and acetic acid decreased with increasing temperature, although the pervaporation fluxes of both water and acetic acid increased. As a result, it was concluded that the increase in the pervaporation flux with temperature was due to the increase in the driving force in terms of transmembrane partial vapor pressure difference with temperature. According to the mechanism proposed herein, a study was also directed to modify as-synthesized membranes for the improvement in their pervaporation performance. It was observed that both the water flux and the separation factor were increased through a membrane treated in alkaline solution under appropriate conditions. (C) 2003 Elsevier Science B.V. All rights reserved.

Mordenite membranes have been prepared on the outer surface of a porous a-alumina tube by seed-assisted crystallization. The kind of silica source was found to have significant influence on the microstructure of the membrane grown on the seeded support. Highly water-selective mordenite membranes were prepared with crystallization time as short as 2-4 h at 180 degreesC. The dehydration of acetic acid by pervaporation was investigated using these thin membranes as functions of temperature and feed concentration. The separation mechanism is discussed. (C) 2003 Published by Elsevier Science B.V.

It was investigated that the effects of preparation methods and conditions for SrFeCo0.5Ox dense membrane on their oxygen permeability. Three different methods, a solid-state reaction method, an evaporation-to-dryness method, and a combined citrate and EDTA complexing method, were applied for the preparation of parent powder. The oxygen flux through membrane at 900 degreesC was increased in the order listed above. The oxygen flux could be greatly improved by repeated calcination and grinding of parent powder. The membrane sintered at a temperature as high as 1200 degreesC showed a higher oxygen flux (0.22 cm(3) (STP)/cm(2) min). (C) 2003 Elsevier Science B.V. All rights reserved.

A study was carried out on the pervaporation of water from water-acetic acid mixtures through tubular ZSM-5 zeolite membranes. ZSM-5 zeolite membranes were prepared on the outer surface of a porous a-alumina tube by the seed-assisted crystallization method in the absence of organic templates. It was observed that water preferentially permeated with selectivities higher than the selectivity based on the vapor-liquid equilibrium in the entire range of acetic acid concentration. The separation mechanism of water through ZSM-5 zeolite membranes was discussed and compared with that through mordenite membranes. It was found that the permeability coefficients of both water and acetic acid decreased with increasing temperature, although the pervaporation fluxes of both water and acetic acid increased. As a result, it was concluded that the increase in the pervaporation flux with temperature was due to the increase in the driving force in terms of transmembrane partial vapor pressure difference with temperature. According to the mechanism proposed herein, a study was also directed to modify as-synthesized membranes for the improvement in their pervaporation performance. It was observed that both the water flux and the separation factor were increased through a membrane treated in alkaline solution under appropriate conditions. (C) 2003 Elsevier Science B.V. All rights reserved.

Template-free nanosized ZSM-5 seeds were prepared from commercially available ZSM-5 powder. By use of these seeds, thin and hydrophilic ZSM-5 zeolite membranes were prepared on the outer surface of a porous a-alumina tube in a clear solution free from organic template. The membranes showed high thermal stability to withstand pretreatment at 400 degreesC, At 270 degreesC, the ideal selectivities for H-2/i-butane and N-2/SF6 were 61 and 20, respectively. The membrane was effective to separate butane isomers at high temperatures. The maximum of the n/i-butane ideal selectivity was 36 at 300 degreesC. The separation factors for a 50/50 n/i-butane mixture were as high as 13 in the temperature range from 300 to 400 degreesC. (C) 2003 Elsevier Science Inc. All rights reserved.

Microporous layered titanium phenylphosphonate, Ti(O3PC6H5)(2) and sulfonated titanium phenylphosphonate, Ti(O3PC6H4SO3H)(0.89) (O3PC6H5)(1.1).1.8H(2)O were prepared in the presence of sodium dodecylsulfate (SDS). Interplanar spacing (d(001)) of titanium phenylphosphonate is 1.43 nm and after sulfonation it increased to 1.64 nm. The surface area of titanium phenylphosphonate is 264 m(2) g(-1).

Microporous layered titanium phenylphosphonate, Ti(O3PC6H5)(2) and sulfonated titanium phenylphosphonate, Ti(O3PC6H4SO3H)(0.89) (O3PC6H5)(1.1).1.8H(2)O were prepared in the presence of sodium dodecylsulfate (SDS). Interplanar spacing (d(001)) of titanium phenylphosphonate is 1.43 nm and after sulfonation it increased to 1.64 nm. The surface area of titanium phenylphosphonate is 264 m(2) g(-1).

The application of the membrane reactor to steam reforming of methanol was studied as a hydrogen producing reaction. The activities, stabilities and selectivities of Cu/ZnO, Ni/Al2O3 and Ru/Al2O3 catalysts were tested using a conventional fixed-bed flow reactor. Ni/Al2O3 catalyst showed the most stable activity at 723 K but relatively low hydrogen yield because of methanation. However, the hydrogen-permeable membrane reactor suppressed methanation and hydrogen yield was enhanced compared with the conventional reactor. The membrane reactor was more effective at higher temperatures and higher W/F.

The application of the membrane reactor to steam reforming of methanol was studied as a hydrogen producing reaction. The activities, stabilities and selectivities of Cu/ZnO, Ni/Al2O3 and Ru/Al2O3 catalysts were tested using a conventional fixed-bed flow reactor. Ni/Al2O3 catalyst showed the most stable activity at 723 K but relatively low hydrogen yield because of methanation. However, the hydrogen-permeable membrane reactor suppressed methanation and hydrogen yield was enhanced compared with the conventional reactor. The membrane reactor was more effective at higher temperatures and higher W/F.

A Pd/alpha-Al2O3 composite membrane was prepared on a porous alpha-Al2O3 disk via the thermal decomposition of bis(hexafluoroacetylacetonato)Pd(II), Pd(hfac)(2). Pd(hfac)(2) was dissolved in supercritical CO2 at 303 K, supplied to the substrate, and thermally decomposed at 403 and 443 K. The decomposition of Pd(hfac)(2) at 443 K resulted in a sufficient pore filling of substrate with Pd as well as the formation of a thin Pd top layer. The hydrogen flux through this membrane was about 1.7 times than that of a electro-less plating Pd membrane with about 20 mum thick. Hydrogen permeation was governed by the solution-diffusion mechanism which gave a high separation selectivity.

Though light cycle oils (LCO) obtained in the fluid catalytic cracking (FCC) are rich in aromatics and sulphur but are insufficient to diesel fuels due to the low cetane number. It is worthwhile to produce alkylbenzenes from LCO without producing small olefinic hydrocarbons through hydrotreating polyaromatic compounds present in the LCO. In the present study tetralin was used as a model compound. Reactions such as ring opening, dealkylation, transalkylation, hydrogen transfer and coke formation were studied using Platinum-supported beta as catalyst. The objective of this study was to investigate the relationship between the crystal size of beta zeolite and catalytic properties for hydrotreatment of tetralin.

Though light cycle oils (LCO) obtained in the fluid catalytic cracking (FCC) are rich in aromatics and sulphur but are insufficient to diesel fuels due to the low cetane number. It is worthwhile to produce alkylbenzenes from LCO without producing small olefinic hydrocarbons through hydrotreating polyaromatic compounds present in the LCO. In the present study tetralin was used as a model compound. Reactions such as ring opening, dealkylation, transalkylation, hydrogen transfer and coke formation were studied using Platinum-supported beta as catalyst. The objective of this study was to investigate the relationship between the crystal size of beta zeolite and catalytic properties for hydrotreatment of tetralin.

A Pd/alpha-Al2O3 composite membrane was prepared on a porous alpha-Al2O3 disk via the thermal decomposition of bis(hexafluoroacetylacetonato)Pd(II), Pd(hfac)(2). Pd(hfac)(2) was dissolved in supercritical CO2 at 303 K, supplied to the substrate, and thermally decomposed at 403 and 443 K. The decomposition of Pd(hfac)(2) at 443 K resulted in a sufficient pore filling of substrate with Pd as well as the formation of a thin Pd top layer. The hydrogen flux through this membrane was about 1.7 times than that of a electro-less plating Pd membrane with about 20 mum thick. Hydrogen permeation was governed by the solution-diffusion mechanism which gave a high separation selectivity.

Though light cycle oils (LCO) obtained in the fluid catalytic cracking (FCC) are rich in aromatics and sulphur but are insufficient to diesel fuels due to the low cetane number. It is worthwhile to produce alkylbenzenes from LCO without producing small olefinic hydrocarbons through hydrotreating polyaromatic compounds present in the LCO. In the present study tetralin was used as a model compound. Reactions such as ring opening, dealkylation, transalkylation, hydrogen transfer and coke formation were studied using Platinum-supported beta as catalyst. The objective of this study was to investigate the relationship between the crystal size of beta zeolite and catalytic properties for hydrotreatment of tetralin.

Zeolite beta with SiO2/Al2O3 ratios from 30 to 730 was synthesized by a steam-assisted crystallization method, and the crystallized products obtained within 24 h were characterized by means of chemical analyses, XRD, FE-SEM, Si-29- MAS NMR, N-2 adsorption, and temperature-programmed decomposition of tetraethylammonium cation occluded in the micropores of zeolite beta. Based on these results, the crystallization mechanism is discussed herein. It was found that agglomerates of nano-particles were formed from a dry gel before the development of a periodical structure in a long-range order, which can be detected by XRD. After several hours of crystallization, morphological changes in nano-particle agglomerates proceeded to give highly crystalline zeolite beta. (C) 2002 Elsevier Science Inc. All rights reserved.

Palladium ion-exchanged zeolites (ZSM-5, mordenite, ferrierite, Y, beta) were tested to evaluate catalytic activity for selective reduction of nitric oxide with methane (CH4-SCR) and stability in the presence of 10% water vapor at a relatively high temperature of 500degreesC. Deactivation of the catalytic activity was inevitable on Pd/HZSM-5 with a Si/Al ratio of 19.8 under the reaction conditions. When the Si/Al ratio decreased, the durability was slightly enhanced. Among the zeolites tested, palladium supported on mordenite showed stable NO conversions. The addition of cobalt effectively stabilized the activity of Pd-H-zeolites, particularly with the addition of 3.3 wt% cobalt onto Pd/HZSM-5, of which no deactivation was noticeable for at least 50 h. Isolated Pd2+ cations on HZSM-5 were the active and selective sites for CH4-SCR. The isolated Pd2+ cations could not be exchanged by Na+ cations in NaCl titration test after the addition of 3.3 wt% cobalt, while NH4NO3 titration revealed that the isolated Pd2+ existed in the sample. This means that Co2+ changes the ion-exchange property of the isolated Pd2+, leading to a much higher stability than Pd/HZSM-5 with regard to durability. The effect of Co2+ on the stability of the isolated Pd2+ cations and their sitings in zeolite cavities is discussed. (C) 2002 Elsevier Science (USA).

Zeolite beta with SiO2/Al2O3 ratios from 30 to 730 was synthesized by a steam-assisted crystallization method, and the crystallized products obtained within 24 h were characterized by means of chemical analyses, XRD, FE-SEM, Si-29- MAS NMR, N-2 adsorption, and temperature-programmed decomposition of tetraethylammonium cation occluded in the micropores of zeolite beta. Based on these results, the crystallization mechanism is discussed herein. It was found that agglomerates of nano-particles were formed from a dry gel before the development of a periodical structure in a long-range order, which can be detected by XRD. After several hours of crystallization, morphological changes in nano-particle agglomerates proceeded to give highly crystalline zeolite beta. (C) 2002 Elsevier Science Inc. All rights reserved.

Palladium ion-exchanged zeolites (ZSM-5, mordenite, ferrierite, Y, beta) were tested to evaluate catalytic activity for selective reduction of nitric oxide with methane (CH4-SCR) and stability in the presence of 10% water vapor at a relatively high temperature of 500degreesC. Deactivation of the catalytic activity was inevitable on Pd/HZSM-5 with a Si/Al ratio of 19.8 under the reaction conditions. When the Si/Al ratio decreased, the durability was slightly enhanced. Among the zeolites tested, palladium supported on mordenite showed stable NO conversions. The addition of cobalt effectively stabilized the activity of Pd-H-zeolites, particularly with the addition of 3.3 wt% cobalt onto Pd/HZSM-5, of which no deactivation was noticeable for at least 50 h. Isolated Pd2+ cations on HZSM-5 were the active and selective sites for CH4-SCR. The isolated Pd2+ cations could not be exchanged by Na+ cations in NaCl titration test after the addition of 3.3 wt% cobalt, while NH4NO3 titration revealed that the isolated Pd2+ existed in the sample. This means that Co2+ changes the ion-exchange property of the isolated Pd2+, leading to a much higher stability than Pd/HZSM-5 with regard to durability. The effect of Co2+ on the stability of the isolated Pd2+ cations and their sitings in zeolite cavities is discussed. (C) 2002 Elsevier Science (USA).

Zeolite/mesoporous molecular sieve composites (ZMC) are made using zeolites as silica-alumina source. XRD patterns of the ZMC show the peaks for both zeolite and mesoporous molecular sieve with hexagonal symmetry. Morphology of the ZMC is different from that of a physical mixture of the two components. Unlike Al-containing mesoporous molecular sieves, the ZMC shows a strong acidity like zeolites. The activity of cracking of n-hexane for ZMC was higher than that of the zeolite. These products are expected to be useful for catalysts and adsorbents for their acidity and pore size.

Zeolite/mesoporous molecular sieve composites (ZMC) are made using zeolites as silica-alumina source. XRD patterns of the ZMC show the peaks for both zeolite and mesoporous molecular sieve with hexagonal symmetry. Morphology of the ZMC is different from that of a physical mixture of the two components. Unlike Al-containing mesoporous molecular sieves, the ZMC shows a strong acidity like zeolites. The activity of cracking of n-hexane for ZMC was higher than that of the zeolite. These products are expected to be useful for catalysts and adsorbents for their acidity and pore size.

It is reported that the first synthesis of MCM-22 zeolite by the vapor-phase transport (VPT) method and the comparison in the morphologies of MCM-22 synthesized by the VPT and hydrothermal synthetic (HTS) methods. In the VPT method, pure MCM-22 zeolite was crystallized at 150degreesC for 5 days and at 175degreesC for 3 days. The morphology of MCM-22 zeolite crystallized by the VPT method was sphere which is an agglomerate of hexagonal thin plates having about 3similar to5 mum in width with less than 100 nm thick. Such morphology was similar to MCM-22 zeolite synthesized by the HTS method under static condition. The crystallization by the VPT method with the addition of HMI onto dry gel gave smaller MCM-22 crystals consisting of thin plates with 1similar to2 mum in width.

It is reported that the first synthesis of MCM-22 zeolite by the vapor-phase transport (VPT) method and the comparison in the morphologies of MCM-22 synthesized by the VPT and hydrothermal synthetic (HTS) methods. In the VPT method, pure MCM-22 zeolite was crystallized at 150degreesC for 5 days and at 175degreesC for 3 days. The morphology of MCM-22 zeolite crystallized by the VPT method was sphere which is an agglomerate of hexagonal thin plates having about 3similar to5 mum in width with less than 100 nm thick. Such morphology was similar to MCM-22 zeolite synthesized by the HTS method under static condition. The crystallization by the VPT method with the addition of HMI onto dry gel gave smaller MCM-22 crystals consisting of thin plates with 1similar to2 mum in width.

It is reported that the first synthesis of MCM-22 zeolite by the vapor-phase transport (VPT) method and the comparison in the morphologies of MCM-22 synthesized by the VPT and hydrothermal synthetic (HTS) methods. In the VPT method, pure MCM-22 zeolite was crystallized at 150degreesC for 5 days and at 175degreesC for 3 days. The morphology of MCM-22 zeolite crystallized by the VPT method was sphere which is an agglomerate of hexagonal thin plates having about 3similar to5 mum in width with less than 100 nm thick. Such morphology was similar to MCM-22 zeolite synthesized by the HTS method under static condition. The crystallization by the VPT method with the addition of HMI onto dry gel gave smaller MCM-22 crystals consisting of thin plates with 1similar to2 mum in width.

It is reported that the first synthesis of MCM-22 zeolite by the vapor-phase transport (VPT) method and the comparison in the morphologies of MCM-22 synthesized by the VPT and hydrothermal synthetic (HTS) methods. In the VPT method, pure MCM-22 zeolite was crystallized at 150degreesC for 5 days and at 175degreesC for 3 days. The morphology of MCM-22 zeolite crystallized by the VPT method was sphere which is an agglomerate of hexagonal thin plates having about 3similar to5 mum in width with less than 100 nm thick. Such morphology was similar to MCM-22 zeolite synthesized by the HTS method under static condition. The crystallization by the VPT method with the addition of HMI onto dry gel gave smaller MCM-22 crystals consisting of thin plates with 1similar to2 mum in width.

A high-silica hexagonal faujasite EMT was crystallized by a steam-assisted crystallization (SAC) method using a crown ether of 1,4,7,10,13,16-hexaoxacyclooctadecane, 18-crown-6, as a structure-directing agent. The growth mechanism of EMT by SAC is quite different from that of EMT by the conventional hydrothermal synthetic method, in which layer-by-layer growth occurs. Another characteristic of SAC is that nanoparticles fuse and the surface of the dry gel is rearranged, resulting in a distinct hexagonal shape for the EMT crystals. Sodium content must be strictly defined when the SAC method is used, and the crystallization temperature must be kept below 408 K to keep the crown ether in the dry gel to obtain a pure phase of EMT.

Beta zeolites with a wide range of Si/2Al ratios from 7 to infinity were synthesized by steam-assisted crystallization method. X-ray diffraction, FE-SEM, and MASNMR studies confirmed the formation of highly crystalline zeolite beta and Al incorporation in the framework under various conditions by the SAC method at temperatures ranging from 373 to 438 K. Na+ and TEA(+) contents occluded in micropores of beta zeolite were determined. Quantitative knowledge on such occluded cations gave great insight on understanding crystallization mechanism of beta. (C) 2001 Published by Elsevier Science B.V.

A high-silica hexagonal faujasite EMT was crystallized by a steam-assisted crystallization (SAC) method using a crown ether of 1,4,7,10,13,16-hexaoxacyclooctadecane, 18-crown-6, as a structure-directing agent. The growth mechanism of EMT by SAC is quite different from that of EMT by the conventional hydrothermal synthetic method, in which layer-by-layer growth occurs. Another characteristic of SAC is that nanoparticles fuse and the surface of the dry gel is rearranged, resulting in a distinct hexagonal shape for the EMT crystals. Sodium content must be strictly defined when the SAC method is used, and the crystallization temperature must be kept below 408 K to keep the crown ether in the dry gel to obtain a pure phase of EMT.

Beta zeolites with a wide range of Si/2Al ratios from 7 to infinity were synthesized by steam-assisted crystallization method. X-ray diffraction, FE-SEM, and MASNMR studies confirmed the formation of highly crystalline zeolite beta and Al incorporation in the framework under various conditions by the SAC method at temperatures ranging from 373 to 438 K. Na+ and TEA(+) contents occluded in micropores of beta zeolite were determined. Quantitative knowledge on such occluded cations gave great insight on understanding crystallization mechanism of beta. (C) 2001 Published by Elsevier Science B.V.

ZSM-5 zeolite having a SiO2/Al2O3 molar ratio of 39.4 was treated in a NaOH alkali solution and the changes in structural and acidic properties were investigated. A siliceous species was selectively dissolved from the framework of zeolite, although a lower amount of Al was also eluted. In this procedure, mesopores with a uniform size were formed on the zeolite, while the microporous structure remained. The acidic property was changed very little quantitatively or qualitatively, even though the catalytic activity for cracking of cumene was enhanced by the alkali-treatment. This can be explained by the facts that adsorptive and diffusive properties of cumene through micropores of the ZSM-5 are increased by the creation of mesopores. (C) 2001 Elsevier Science B.V. All rights reserved.

ZSM-5 zeolite having a SiO2/Al2O3 molar ratio of 39.4 was treated in a NaOH alkali solution and the changes in structural and acidic properties were investigated. A siliceous species was selectively dissolved from the framework of zeolite, although a lower amount of Al was also eluted. In this procedure, mesopores with a uniform size were formed on the zeolite, while the microporous structure remained. The acidic property was changed very little quantitatively or qualitatively, even though the catalytic activity for cracking of cumene was enhanced by the alkali-treatment. This can be explained by the facts that adsorptive and diffusive properties of cumene through micropores of the ZSM-5 are increased by the creation of mesopores. (C) 2001 Elsevier Science B.V. All rights reserved.

A novel organic-ceramic membrane having stable Si-C bonds was developed for separation of high temperature organic solutions. Porous vycor glass was employed for a substrate which was modified by a series of chemical vapor deposition (CVD) and hydrosilylation. 1,3,5,7-Tetramethylcyclotetrasiloxane (1-14) was used as a CVD source in order to introduce Si-H bonds on the surface of porous vycor glass. The Si-H bonds were then catalytically hydrosilylated with olefins. As a result, organic functional groups were introduced via Si-C bonds. A compact membrane was obtained when CVD treatment was carried out at 343 K. The membrane that was modified by the hydrosilylation of styrene showed benzene permselectivity in benzene/cyclohexane vapor permeation test at 373 K. The separation factor of benzene over cyclohexane was 2.9 and benzene flux was 1.2 x 10(-8) mol m(-2)s(-1)Pa(-1), and the permeation properties are stable for more than 1000 min at 373 K.

A novel organic-ceramic membrane having stable Si-C bonds was developed for separation of high temperature organic solutions. Porous vycor glass was employed for a substrate which was modified by a series of chemical vapor deposition (CVD) and hydrosilylation. 1,3,5,7-Tetramethylcyclotetrasiloxane (1-14) was used as a CVD source in order to introduce Si-H bonds on the surface of porous vycor glass. The Si-H bonds were then catalytically hydrosilylated with olefins. As a result, organic functional groups were introduced via Si-C bonds. A compact membrane was obtained when CVD treatment was carried out at 343 K. The membrane that was modified by the hydrosilylation of styrene showed benzene permselectivity in benzene/cyclohexane vapor permeation test at 373 K. The separation factor of benzene over cyclohexane was 2.9 and benzene flux was 1.2 x 10(-8) mol m(-2)s(-1)Pa(-1), and the permeation properties are stable for more than 1000 min at 373 K.

Al-free Ti-Si-beta was synthesized by a steam-assisted crystallization (SAC) method using tetraethylammonium hydroxide as a structure-directing agent. It was noted that Na in a parent gel was essential for synthesizing highly crystalline Ti-Si-beta by means of the SAC method. An absorption band at 225 nm, assigned to isolated Ti species, and another band at around 270 nm appeared in the UV spectra of the Ti-Si-beta. The latter absorption band decreased upon ion exchange of as-synthesized materials with 1 M aqueous NH4NO3 solution, and this treatment did not change the SiO2/TiO2 molar ratio in Ti-Si-beta. The Q(3) signal in the Si-29-NMR spectrum almost disappeared and the amount of H2O adsorbed decreased due to the NH4+ exchange of Ti-Si-beta. The NH4+ exchange resulted in a higher catalytic activity of the zeolite far cyclohexene epoxidation with H2O2 and a high selectivity toward epoxide compared with the H2SO4-treated Ti-Si-beta and AI-containing Ti-beta samples prepared in this study. Summarizing these results, the NH4+ exchange of Ti-Si-beta zeolite is found to induce a hydrophobic environment around Ti sites without detitanation from the zeolite framework. (C) 2001 Academic Press.

Microstructures of spherical and coffin-shaped MFI zeolite and its effect on the catalytic activity for cumene cracking were studied. While spherical MFI was composed of nanoparticles, coffin-shaped one has a layered structure where nanoparticles with ~ 30 nm in size were accumulated on the dense core. Both the thickness of nano-particles layer and mesopore volume linearly correlated with the activity for cumene cracking, suggesting that the mesopores in MFI particles formed during nanoparticles agglomeration, and that the reaction rate of cumene cracking was significantly affected by the diffusion of cumene molecule in the nanoparticles agglomerating layer. This is an abstract of a paper presented at the 13th International Zeolite Conference (Montpellier, France 7/8-13/2001).

A highly oriented mordenite membrane with c-axis of crystals perpendicular to the support surface was successfully prepared on a porous α-alumina support. Seeding was necessary to form a compact layer of mordenite. The "evolutionary selection" mechanism significantly contributed to the formation of a sharply oriented mordenite layer. Pervaporation results for separation of a water/iso-propanol mixture exhibited highly preferential permeation of water through the oriented mordenite membrane. This is an abstract of a paper presented at the 13th International Zeolite Conference (Montpellier, France 7/8-13/2001).

Microstructures of spherical and coffin-shaped MFI zeolite and its effect on the catalytic activity for cumene cracking were studied. While spherical MFI was composed of nanoparticles, coffin-shaped one has a layered structure where nanoparticles with ~ 30 nm in size were accumulated on the dense core. Both the thickness of nano-particles layer and mesopore volume linearly correlated with the activity for cumene cracking, suggesting that the mesopores in MFI particles formed during nanoparticles agglomeration, and that the reaction rate of cumene cracking was significantly affected by the diffusion of cumene molecule in the nanoparticles agglomerating layer. This is an abstract of a paper presented at the 13th International Zeolite Conference (Montpellier, France 7/8-13/2001).

A highly oriented mordenite membrane with c-axis of crystals perpendicular to the support surface was successfully prepared on a porous α-alumina support. Seeding was necessary to form a compact layer of mordenite. The "evolutionary selection" mechanism significantly contributed to the formation of a sharply oriented mordenite layer. Pervaporation results for separation of a water/iso-propanol mixture exhibited highly preferential permeation of water through the oriented mordenite membrane. This is an abstract of a paper presented at the 13th International Zeolite Conference (Montpellier, France 7/8-13/2001).

MFI-type zeolitic membranes were prepared by a vapor-phase transport (VPT) method on porous alpha-alumina flat disks. Single- and mixed-gas permeation measurements of butane isomers were performed in the temperature range of 300-375 K. The separation factor was always greater than the ideal selectivity. This result is explained by the preferential adsorption of n-butane on MFI in the binary system.
The pervaporation tests for xylene isomers were performed at 303 K. p-Xylene was the most permeable component in the unary system. In the permeation measurements of a binary mixture of p-xylene/m-xylene and a ternary mixture of p-xylene/m-xylene/o-xylene, p-xylene predominantly permeated in the early stage, and then, the Aux of p-xylene decreased gradually and finally became lower than that of the other xylene isomers. The adsorption of m-xylene in the pores of MFI seemed to block the permeation of p-xylene. (C) 2000 Elsevier Science B.V. All rights reserved.

MFI-type zeolitic membranes were prepared by a vapor-phase transport (VPT) method on porous alpha-alumina flat disks. Single- and mixed-gas permeation measurements of butane isomers were performed in the temperature range of 300-375 K. The separation factor was always greater than the ideal selectivity. This result is explained by the preferential adsorption of n-butane on MFI in the binary system.
The pervaporation tests for xylene isomers were performed at 303 K. p-Xylene was the most permeable component in the unary system. In the permeation measurements of a binary mixture of p-xylene/m-xylene and a ternary mixture of p-xylene/m-xylene/o-xylene, p-xylene predominantly permeated in the early stage, and then, the Aux of p-xylene decreased gradually and finally became lower than that of the other xylene isomers. The adsorption of m-xylene in the pores of MFI seemed to block the permeation of p-xylene. (C) 2000 Elsevier Science B.V. All rights reserved.

Treatment of ZSM-5 in alkaline solution dramatically changes morphology of the ZSM-5, leading to the formation of mesopores whose size is almost uniform without destruction of microporous structure.

Polycrystalline ferrierite/alumina composite membranes were prepared by a vapor-phase transport method. Pervaporation of m-xylene and 1,3,5-triisopropylbenzene was then used to evaluate the compactness of the membranes.
Permeation measurements were carried out for hydrogen, helium, methane, n-butane, i-butane and sulfur hexafluoride at 300-375 K. Ideal selectivities and the mixed gas separation factors were compared. The separation factor of butane isomers depended on the compactness of the membrane. The separation factor of n-butane/i-butane was as high as 40-70 at 375 K, and no detectable permeation flux of m-xylene was observed at 303 K.
Separation of a 25/75 p-xylene/m-xylene mixture was also performed at 303 K using pervaporation. The permeation of p-xylene was detectable, whereas that of m-xylene was below the detection limit of the experiment. The separation factor of p-xylene to m-xylene was greater than 16, which is much higher than the value of 1.0 expected from the vapor-liquid equilibrium. (C) 2000 Elsevier Science B.V. All rights reserved.

Polycrystalline ferrierite/alumina composite membranes were prepared by a vapor-phase transport method. Pervaporation of m-xylene and 1,3,5-triisopropylbenzene was then used to evaluate the compactness of the membranes.
Permeation measurements were carried out for hydrogen, helium, methane, n-butane, i-butane and sulfur hexafluoride at 300-375 K. Ideal selectivities and the mixed gas separation factors were compared. The separation factor of butane isomers depended on the compactness of the membrane. The separation factor of n-butane/i-butane was as high as 40-70 at 375 K, and no detectable permeation flux of m-xylene was observed at 303 K.
Separation of a 25/75 p-xylene/m-xylene mixture was also performed at 303 K using pervaporation. The permeation of p-xylene was detectable, whereas that of m-xylene was below the detection limit of the experiment. The separation factor of p-xylene to m-xylene was greater than 16, which is much higher than the value of 1.0 expected from the vapor-liquid equilibrium. (C) 2000 Elsevier Science B.V. All rights reserved.

MFI-type lozenge zeolitic membranes were prepared by a vapor-phase transport method on porous or-alumina flat disks. Pure or mixed gas permeation measurements of butane isomers were performed at 375 K using two methods: pressure gradient (PG) and concentration gradient (CG) methods. Pure gas permeation measurements of H-2, He, CH4, N-2, O-2, CO2 and SF6 were also carried out using PG method. Counter-diffusion of helium as a sweep gas was evaluated by determining the gas composition at the outlet of the feed side. It was confirmed that the counter-diffusion of helium occurs only when the total pressure of the feed side was <80 kPa.
In the mixed gas permeation measurements, the value of separation factor depended on the method of gas permeation. The separation factors of n-butane to i-butane were ca. 10 in the PG method and 30-60 in the CG method. (C) 2000 Elsevier Science B.V. All rights reserved.

Catalytic performance of Ir catalysts for reduction of nitric oxide with carbon monoxide in the presence of SO, and excess oxygen was investigated. NO was selectively reduced with CO on Ir/silicalite in an oxidizing atmosphere containing 1% to 10% O-2 in the temperature range of 300-500 degrees C. The catalytic activity was scarcely influenced by 150 ppm SO2.

MFI-type lozenge zeolitic membranes were prepared by a vapor-phase transport method on porous or-alumina flat disks. Pure or mixed gas permeation measurements of butane isomers were performed at 375 K using two methods: pressure gradient (PG) and concentration gradient (CG) methods. Pure gas permeation measurements of H-2, He, CH4, N-2, O-2, CO2 and SF6 were also carried out using PG method. Counter-diffusion of helium as a sweep gas was evaluated by determining the gas composition at the outlet of the feed side. It was confirmed that the counter-diffusion of helium occurs only when the total pressure of the feed side was <80 kPa.
In the mixed gas permeation measurements, the value of separation factor depended on the method of gas permeation. The separation factors of n-butane to i-butane were ca. 10 in the PG method and 30-60 in the CG method. (C) 2000 Elsevier Science B.V. All rights reserved.

Catalytic performance of Ir catalysts for reduction of nitric oxide with carbon monoxide in the presence of SO, and excess oxygen was investigated. NO was selectively reduced with CO on Ir/silicalite in an oxidizing atmosphere containing 1% to 10% O-2 in the temperature range of 300-500 degrees C. The catalytic activity was scarcely influenced by 150 ppm SO2.

Mordenite membranes prepared on alpha-alumina tubular supports by in situ hydrothermal synthesis using organic template-free media showed high water permselectivity for pervaporation of water-isopropyl alcohol mixtures.

Mordenite membranes prepared on alpha-alumina tubular supports by in situ hydrothermal synthesis using organic template-free media showed high water permselectivity for pervaporation of water-isopropyl alcohol mixtures.

The active site in ZSM-5 zeolite-supported palladium, which shows the catalytic activity for NO reduction with methane as a reducing agent, has been investigated qualitatively and quantitatively by means of NO chemisorption and NaCl titration, comparing with PdO supported on silica. Palladium species in 0.4 wt.% Pd loaded H-ZSM-5 can adsorb NO equimolarly after calcination at 773 K, and almost all the NO was desorbed at around 673 K; while the palladium species on PdO/SiO2 hardly adsorbed NO. The palladium species in Pd(0.4)/H-ZSM-5 are ion-exchangeable with Na+ in NaCl solution, indicating that they exist in a cationic state of an isolated Pd2+. This method for quantitative analysis of the isolated Pd2+ cations is named as 'NaCl titration'. The amount of the isolated Pd2+ cationic species increased with increasing palladium content on Pd/H-ZSM-5, and PdO co-existed above 1 wt.%. The amount of the isolated Pd2+ cation was unchanged after the reaction of NO2-CH4, NO2-CH4-O-2, or CH4-O-2 at 673 K, while the adsorbed amount of NO per the Pd2+ as determined by NO-TPD decreased after the NO2-CH4-O-2 reaction. It was found by NaCl titration that the catalytic activity of Pd/H-ZSM-5 for NO2-CH4-O-2 reaction increased with increasing amount of the isolated Pd2+ cationic species up to 0.7 wt.%, while the increase in the amount of PdO led to decrease in selectivity towards NO2 reduction. The palladium species that are active and selective for NO reduction with CH4 will be proposed. (C) 1999 Elsevier Science B.V. All rights reserved.

The active site in ZSM-5 zeolite-supported palladium, which shows the catalytic activity for NO reduction with methane as a reducing agent, has been investigated qualitatively and quantitatively by means of NO chemisorption and NaCl titration, comparing with PdO supported on silica. Palladium species in 0.4 wt.% Pd loaded H-ZSM-5 can adsorb NO equimolarly after calcination at 773 K, and almost all the NO was desorbed at around 673 K; while the palladium species on PdO/SiO2 hardly adsorbed NO. The palladium species in Pd(0.4)/H-ZSM-5 are ion-exchangeable with Na+ in NaCl solution, indicating that they exist in a cationic state of an isolated Pd2+. This method for quantitative analysis of the isolated Pd2+ cations is named as 'NaCl titration'. The amount of the isolated Pd2+ cationic species increased with increasing palladium content on Pd/H-ZSM-5, and PdO co-existed above 1 wt.%. The amount of the isolated Pd2+ cation was unchanged after the reaction of NO2-CH4, NO2-CH4-O-2, or CH4-O-2 at 673 K, while the adsorbed amount of NO per the Pd2+ as determined by NO-TPD decreased after the NO2-CH4-O-2 reaction. It was found by NaCl titration that the catalytic activity of Pd/H-ZSM-5 for NO2-CH4-O-2 reaction increased with increasing amount of the isolated Pd2+ cationic species up to 0.7 wt.%, while the increase in the amount of PdO led to decrease in selectivity towards NO2 reduction. The palladium species that are active and selective for NO reduction with CH4 will be proposed. (C) 1999 Elsevier Science B.V. All rights reserved.

The formation of a ferrierite (FER) membrane by a vapor-phase transport method is discussed. The formation process was studied using X-ray diffraction, scanning electron microscopy (SEM), field emission-SEM and energy dispersive X-ray analysis. The same location on the top surface was repeatedly observed at different crystallization times using SEM. It was found that an aluminosilicate species formed from a dry gel layer was mobile over the surface of support during crystallization. This intermediate aluminosilicate species penetrated into the pores of the alumina support to fill them, generating a compact FER-alumina composite layer. (C) 1999 Elsevier Science B.V. All rights reserved.

The formation of a ferrierite (FER) membrane by a vapor-phase transport method is discussed. The formation process was studied using X-ray diffraction, scanning electron microscopy (SEM), field emission-SEM and energy dispersive X-ray analysis. The same location on the top surface was repeatedly observed at different crystallization times using SEM. It was found that an aluminosilicate species formed from a dry gel layer was mobile over the surface of support during crystallization. This intermediate aluminosilicate species penetrated into the pores of the alumina support to fill them, generating a compact FER-alumina composite layer. (C) 1999 Elsevier Science B.V. All rights reserved.

We propose a new technique, "position-controlled CVD using catalytic reaction," to modify pore structure. By loading the catalyst for the reverse water gas shift reaction on a support that is to be modified, He can confine the hydrolysis reaction zone to a narrow region surrounding the catalyst where H2O is generated, An anodic alumina membrane with pore size of 26 nm was used as the support. Reactant gases, H-2, CO2 and TiCl4, were led into the same side of the membrane. The effects of reaction conditions on pore modification are investigated on the basis of FE-SEM observations and permeation tests, The pore size and permeance through the membrane gradually decrease with reaction time. Deposition morphology changes with reaction conditions, such as temperature, and H-2, CO2 and TiCl4 feed rates. In some cases, particles with 0.1-1 mu m diameter are formed on the outer surface of membrane.

A new method was proposed to assess the surface properties of coal hy adsorption of metanil yellow using a continuous feed sg stem. The area fraction of the hydrophobic site on the exterior surface, alpha(m), was measured for Datong, Tyanfu, Shanxi No. 1, Illinois No. 6 and Blair Athol. Except for Tyanfu coal, the order of the values of alpha(m) is consistent with that of carbonaceous materials recovery. The,metanil yellow adsorption experiment requires no specific preparation, and can be applied to powder samples.

The behavior of Datong coal particles in a flotation column was investigated in a batchwise operation using a gas distributor evolving uniform bubbles by varying the superficial gas velocity and column height. The value of superficial gas velocity was controlled at 0.66 or 1.99 cm s(-1)
The time course of ash content in floats was measured when column height was 1.85 In, The ash content in clean coal was larger for higher superficial gas velocity. The hydrophobicity of coal particles recovered from the top of the column was evaluated by means of a film flotation method. Hydrophilic particles having the critical wetting surface tension of particles, gamma(c), greater than 60 mN m(-1) floated well for higher superficial gas velocity, The weight percent of fractions having gamma(c) above 60 mN m(-1) was 29.5, 31.9 and 40.5% for 0.25, 2.00 and 4.25 min. respectively. These values increased with sampling time, and were much greater than those for the lower superficial gas velocity. At lower superficial gas velocity, the hydrophobic coal particles seem to be selectively floated by colliding and attaching to the bubble surfaces. On the other hand, at higher superficial gas velocity, hydrophilic particles that are difficult to attach to bubbles seem to be entrained in the turbulent wake of bubble swamis and float.
The grade of clean coal was better for the lower superficial gas velocity, however, carbonaceous materials recovery was lower than that for higher superficial gas velocity. Carbonaceous materials recovery was improved by increasing the recovery zone height.

We propose a new technique, "position-controlled CVD using catalytic reaction," to modify pore structure. By loading the catalyst for the reverse water gas shift reaction on a support that is to be modified, He can confine the hydrolysis reaction zone to a narrow region surrounding the catalyst where H2O is generated, An anodic alumina membrane with pore size of 26 nm was used as the support. Reactant gases, H-2, CO2 and TiCl4, were led into the same side of the membrane. The effects of reaction conditions on pore modification are investigated on the basis of FE-SEM observations and permeation tests, The pore size and permeance through the membrane gradually decrease with reaction time. Deposition morphology changes with reaction conditions, such as temperature, and H-2, CO2 and TiCl4 feed rates. In some cases, particles with 0.1-1 mu m diameter are formed on the outer surface of membrane.

A new method was proposed to assess the surface properties of coal hy adsorption of metanil yellow using a continuous feed sg stem. The area fraction of the hydrophobic site on the exterior surface, alpha(m), was measured for Datong, Tyanfu, Shanxi No. 1, Illinois No. 6 and Blair Athol. Except for Tyanfu coal, the order of the values of alpha(m) is consistent with that of carbonaceous materials recovery. The,metanil yellow adsorption experiment requires no specific preparation, and can be applied to powder samples.

The behavior of Datong coal particles in a flotation column was investigated in a batchwise operation using a gas distributor evolving uniform bubbles by varying the superficial gas velocity and column height. The value of superficial gas velocity was controlled at 0.66 or 1.99 cm s(-1)
The time course of ash content in floats was measured when column height was 1.85 In, The ash content in clean coal was larger for higher superficial gas velocity. The hydrophobicity of coal particles recovered from the top of the column was evaluated by means of a film flotation method. Hydrophilic particles having the critical wetting surface tension of particles, gamma(c), greater than 60 mN m(-1) floated well for higher superficial gas velocity, The weight percent of fractions having gamma(c) above 60 mN m(-1) was 29.5, 31.9 and 40.5% for 0.25, 2.00 and 4.25 min. respectively. These values increased with sampling time, and were much greater than those for the lower superficial gas velocity. At lower superficial gas velocity, the hydrophobic coal particles seem to be selectively floated by colliding and attaching to the bubble surfaces. On the other hand, at higher superficial gas velocity, hydrophilic particles that are difficult to attach to bubbles seem to be entrained in the turbulent wake of bubble swamis and float.
The grade of clean coal was better for the lower superficial gas velocity, however, carbonaceous materials recovery was lower than that for higher superficial gas velocity. Carbonaceous materials recovery was improved by increasing the recovery zone height.

Coal particles contain oxygen functional groups such as hydroxyl, carbonyl, and carboxyl, and mineral matters that contribute surface hydrophilicity, The occurrence of them varies considerably from coal to coal, hence the characteristics of column flotation changes from coal to coal. We expected that the characteristics of column flotation could be simply evaluated by using the area fraction of oxygen functional group sites on the exterior surface of the coal particles.
In this work, we conducted column flotation for Shanxi (anthracite), Tyanfu (bituminous), Blair Athol (bituminous), Datong (bituminous), and Illinois (brown coal). The order of carbonaceous materials recovery was found to be Tyanfu > Shanxi > Blair Athol > Datong > Illinois, We also evaluated the area fraction of hydroxyl group on the exterior surface of the coal particles, alpha(ex-OH), and that in the coal particles, alpha i(n-OH). For Datong coal, the value of alpha(ex-OH) was larger than that of alpha(in-OH). It means that Datong coal was slightly oxidized. The order of carbonaceous materials recovery was inconsistent with that of alpha(ex-OH) for the three kinds of bituminous coal. For Shanxi anthracite coal, the flotability is evaluated by considering the wettability of the hydrophobic sites as well as the hydrophilic sites.

Coal particles contain oxygen functional groups such as hydroxyl, carbonyl, and carboxyl, and mineral matters that contribute surface hydrophilicity, The occurrence of them varies considerably from coal to coal, hence the characteristics of column flotation changes from coal to coal. We expected that the characteristics of column flotation could be simply evaluated by using the area fraction of oxygen functional group sites on the exterior surface of the coal particles.
In this work, we conducted column flotation for Shanxi (anthracite), Tyanfu (bituminous), Blair Athol (bituminous), Datong (bituminous), and Illinois (brown coal). The order of carbonaceous materials recovery was found to be Tyanfu > Shanxi > Blair Athol > Datong > Illinois, We also evaluated the area fraction of hydroxyl group on the exterior surface of the coal particles, alpha(ex-OH), and that in the coal particles, alpha i(n-OH). For Datong coal, the value of alpha(ex-OH) was larger than that of alpha(in-OH). It means that Datong coal was slightly oxidized. The order of carbonaceous materials recovery was inconsistent with that of alpha(ex-OH) for the three kinds of bituminous coal. For Shanxi anthracite coal, the flotability is evaluated by considering the wettability of the hydrophobic sites as well as the hydrophilic sites.

Crystallization of zeolite using an organic compound as a structure-directing agent (SDA) and phase transformation of zeolite into another phase were investigated by means of a new crystallization method of dry gel conversion (DGC). Different types of zeolite were crystallized by DGC with SDAs having different sizes in alkyl chains of organics. Not the size of SDAs but the type of them determines the phase crystallized. Phase transformation of zeolite beta occurred into a new phase of zeolite OU-1, which has the same topology as zeolites SSZ-31 and NCL-1. From XRD and SEM observations, it can be concluded that the phase transformation occurs via surface-mediated nucleation and growth without significant dissolution nor destruction of zeolite structure.

Recently the dry gel conversion (DGC) technique, where a hydrogel is dried and the resultant dry gel is converted into microporous crystals in steam or in a mixed vapor of steam and organic structure-directing agents (SDAs), has been developed. It has been shown that a wide variety of microporous crystals, pure silica microporous crystals, aluminosilicates, metallosilicates, and aluminophosphates, can be synthesized using the DGC method. Remarkable results have been reported in the synthesis of BEA types zeolites, namely aluminosilicate, titaniumsilicate, zincosilicate, and borosilicate with BEA topology, using tetraethylammonium hydroxide, a commercially available SDA. It has also been found that zeolite OU-1, probably analogous to SSZ-31 and NCL-1, is formed via phase transformation from BEA. Dense zeolite coatings like membranes are possible using this method. Characteristics of the DGC method are discussed in detail.

Crystallization of zeolite using an organic compound as a structure-directing agent (SDA) and phase transformation of zeolite into another phase were investigated by means of a new crystallization method of dry gel conversion (DGC). Different types of zeolite were crystallized by DGC with SDAs having different sizes in alkyl chains of organics. Not the size of SDAs but the type of them determines the phase crystallized. Phase transformation of zeolite beta occurred into a new phase of zeolite OU-1, which has the same topology as zeolites SSZ-31 and NCL-1. From XRD and SEM observations, it can be concluded that the phase transformation occurs via surface-mediated nucleation and growth without significant dissolution nor destruction of zeolite structure.

Recently the dry gel conversion (DGC) technique, where a hydrogel is dried and the resultant dry gel is converted into microporous crystals in steam or in a mixed vapor of steam and organic structure-directing agents (SDAs), has been developed. It has been shown that a wide variety of microporous crystals, pure silica microporous crystals, aluminosilicates, metallosilicates, and aluminophosphates, can be synthesized using the DGC method. Remarkable results have been reported in the synthesis of BEA types zeolites, namely aluminosilicate, titaniumsilicate, zincosilicate, and borosilicate with BEA topology, using tetraethylammonium hydroxide, a commercially available SDA. It has also been found that zeolite OU-1, probably analogous to SSZ-31 and NCL-1, is formed via phase transformation from BEA. Dense zeolite coatings like membranes are possible using this method. Characteristics of the DGC method are discussed in detail.

Synthesis of borosilicate zeolites, namely [B]-BEA, [B]-MFI and [B]-MTW by dry gel conversion (DGC) method was described for the first time. Phase selection and thereby the outcome of the product was dependent upon the gel composition, mainly on the SiO2/B2O3 ratio and the TEAOH content.

Zeolite BEA with SiO2/Al2O3 ratios ranging from 30 to 740 were crystallized at 413 and 453 K by the dry gel conversion technique. The particle size of the products increased with increasing SiO2/Al2O3 ratio as well as with increasing crystallization temperature. In as-synthesized BEA, the TEA+ ions interacting with Si-O- decomposed between 473 and 673 K and those interacting with Al-O- were cleaved between 673 and 798 K. During their elimination, the TEA+ ions interacting with Al-O- underwent higher degradation than those interacting with Si-O-. Chemical compositions showed the least influence on the fractions of decomposition product during the elimination between 473 and 673 K. The framework of H-BEA and NH4-BEA zeolites with SiO2/Al2O3 ratios ranging from 400 to 740 were stable even at 1373 K, whereas H-BEA with SiO2/Al2O3 = 30 was stable only up to 1173 K and became amorphous when calcined at 1373 K. After calcination at 1373 K, Na-BEA with SiO2/Al2O3 = 400 and 730 were transformed to tridymite (dense phase) whereas that with SiO2/Al2O3 = 30 became amorphous. The elimination of Na+ ions is necessary to have a BEA remain stable above 1173 K. © 1998 Elsevier Science B.V. All rights reserved.

Zeolite with BEA structure was prepared using a new crystallization method called 'Dry Gel Conversion Technique'. This dry gel conversion technique is a convenient method to prepare zeolites and enables one to synthesize zeolite BEA with SiO2/Al2O3 ratios from 30 to infinity using tetraethylammonium hydroxide (TEAOH) as a structure directing agent. Zeolite BEA with SiO2/Al2O3 ratios from 30 to 730 were rapidly crystallized in 3 and 12 h, respectively. The Al-27 NMR spectrum for BEA with SiO2/Al2O3 ratio of 30 confirmed the absence of octahedrally coordinated aluminum. The crystallization rates were higher for BEA with low SiO2/Al2O3 ratios than for those with high SiO2/Al2O3 ratios. BEA crystallized by this method had uniform particles of about 60 nm. Higher Na+ ion concentrations in the gel promoted the formation of high silica BEA. Elimination of occluded TEA cations took place at lower temperatures (around 623 K) in high silica BEA than that in BEA with low SiO2/Al2O3 ratios (around 900 K). This method also allowed to synthesize BEA in the form of self-bonded pellets. (C) 1998 Elsevier Science B.V.

Synthesis of borosilicate zeolites, namely [B]-BEA, [B]-MFI and [B]-MTW by dry gel conversion (DGC) method was described for the first time. Phase selection and thereby the outcome of the product was dependent upon the gel composition, mainly on the SiO2/B2O3 ratio and the TEAOH content.

Zeolite BEA with SiO2/Al2O3 ratios ranging from 30 to 740 were crystallized at 413 and 453 K by the dry gel conversion technique. The particle size of the products increased with increasing SiO2/Al2O3 ratio as well as with increasing crystallization temperature. In as-synthesized BEA, the TEA+ ions interacting with Si-O- decomposed between 473 and 673 K and those interacting with Al-O- were cleaved between 673 and 798 K. During their elimination, the TEA+ ions interacting with Al-O- underwent higher degradation than those interacting with Si-O-. Chemical compositions showed the least influence on the fractions of decomposition product during the elimination between 473 and 673 K. The framework of H-BEA and NH4-BEA zeolites with SiO2/Al2O3 ratios ranging from 400 to 740 were stable even at 1373 K, whereas H-BEA with SiO2/Al2O3 = 30 was stable only up to 1173 K and became amorphous when calcined at 1373 K. After calcination at 1373 K, Na-BEA with SiO2/Al2O3 = 400 and 730 were transformed to tridymite (dense phase) whereas that with SiO2/Al2O3 = 30 became amorphous. The elimination of Na+ ions is necessary to have a BEA remain stable above 1173 K. © 1998 Elsevier Science B.V. All rights reserved.

Zeolite with BEA structure was prepared using a new crystallization method called 'Dry Gel Conversion Technique'. This dry gel conversion technique is a convenient method to prepare zeolites and enables one to synthesize zeolite BEA with SiO2/Al2O3 ratios from 30 to infinity using tetraethylammonium hydroxide (TEAOH) as a structure directing agent. Zeolite BEA with SiO2/Al2O3 ratios from 30 to 730 were rapidly crystallized in 3 and 12 h, respectively. The Al-27 NMR spectrum for BEA with SiO2/Al2O3 ratio of 30 confirmed the absence of octahedrally coordinated aluminum. The crystallization rates were higher for BEA with low SiO2/Al2O3 ratios than for those with high SiO2/Al2O3 ratios. BEA crystallized by this method had uniform particles of about 60 nm. Higher Na+ ion concentrations in the gel promoted the formation of high silica BEA. Elimination of occluded TEA cations took place at lower temperatures (around 623 K) in high silica BEA than that in BEA with low SiO2/Al2O3 ratios (around 900 K). This method also allowed to synthesize BEA in the form of self-bonded pellets. (C) 1998 Elsevier Science B.V.

The mechanism of formation of ferrierite (FER) membrane on an alumina support by a vapor-phase transport (VPT) method was studied using XRD, SEM, FE-SEM and EDX. The XRD measurement for a FER membrane after the removal of FER particles formed on the support showed that FER was formed in the pores of the alumina support, namely, a FER-alumina composite layer was formed. The FE-SEM image for the cross-sectional view of the FER-alumina composite layer showed that FER nanocrystals of about 50 nm diameter grew in the pores of the alumina support. Pervaporation tests for benzene/p-xylene mixtures were performed at 303 K. Even when the concentration of benzene in the feed solution was extremely small (0.5 mol%), the flux of benzene through the FER membrane was still greater than that of p-xylene. Therefore, a separation factor as high as 600 was obtained in the low feed concentration of benzene. Such a high selectivity for the benzene/p-xylene mixture suggested that the selectivity for the benzene/p-xylene mixture appears at the pore mouths of FER on the feed side of the FER-alumina composite layer. (C) 1997 Elsevier Science B.V.

This article is intended to describe recent progress in the synthesis of zeolitic membranes and their permeation properties. While hydrothermal synthesis has been widely employed for zeolitic-membrane synthesis, the development of a new technique for zeolite synthesis, vapor-phase transport (VPT), has enabled us to prepare pinhole-free, zeolite-porous support composite membranes. This article consists of three sections that describe: a survey of the hydrothermal synthesis of zeolitic membranes, our synthesis results and the formation mechanism of zeolitic membranes by the VPT method as well as some permeation results to show the prospects of zeolitic membranes.

This article is intended to describe recent progress in the synthesis of zeolitic membranes and their permeation properties. While hydrothermal synthesis has been widely employed for zeolitic-membrane synthesis, the development of a new technique for zeolite synthesis, vapor-phase transport (VPT), has enabled us to prepare pinhole-free, zeolite-porous support composite membranes. This article consists of three sections that describe: a survey of the hydrothermal synthesis of zeolitic membranes, our synthesis results and the formation mechanism of zeolitic membranes by the VPT method as well as some permeation results to show the prospects of zeolitic membranes.

Zeolitic membranes were synthesized on a porous alumina support by the vapor-phase transport method using one of two alumina sources: aluminum sulfate and sodium aluminate. By choosing the appropriate period and temperature for drying the aluminosilicate gel on the alumina support, MOR, FER and MFI could be synthesized. MOR was formed when the water content in the dry gel was high. As the water content decreased, FER and MFI were formed sequentially. Preferential formation of MFI was achieved by treating the dry gel at 373 K. The temperature at which the support was dipped in the parent gel also influenced the type of zeolite formed, although the effect of drying conditions was more pronounced. A similar trend was found for both aluminum sulfate and sodium aluminate. When the alumina source was sodium aluminate and the aluminosilicate gel was treated at 373 K, a preferentially oriented MFI membrane could be synthesized, as the (a00) and (0b0) crystal faces were oriented in parallel to the surface of porous alumina support. The uniform and dense morphology of the dry gel seems to account for the appearance of the orientation. © 1997 Elsevier Science B.V.

Mordenite (MOR) and ferrierite (FER) membranes without any pinhole and crack were synthesized by a vapor-phase transport method. The permeance of H-2, He, CH4, N-2, O-2 and CO2 was determined at 290-400 K; which showed minimum with increasing temperatures for most cases. In the parallel diffusion model was proposed, molecules adsorbed in a micropore are assumed to diffuse in parallel through the central region of the pore and along the wall region of the pore. This parallel diffusion model accounts for the effect of pore Size of MOR and FER on the permeation and expresses the experimental data well. The interaction between gas molecules and pore walls are evaluated for each gas.

The mechanism of formation of ferrierite (FER) membrane on an alumina support by a vapor-phase transport (VPT) method was studied using XRD, SEM, FE-SEM and EDX. The XRD measurement for a FER membrane after the removal of FER particles formed on the support showed that FER was formed in the pores of the alumina support, namely, a FER-alumina composite layer was formed. The FE-SEM image for the cross-sectional view of the FER-alumina composite layer showed that FER nanocrystals of about 50 nm diameter grew in the pores of the alumina support. Pervaporation tests for benzene/p-xylene mixtures were performed at 303 K. Even when the concentration of benzene in the feed solution was extremely small (0.5 mol%), the flux of benzene through the FER membrane was still greater than that of p-xylene. Therefore, a separation factor as high as 600 was obtained in the low feed concentration of benzene. Such a high selectivity for the benzene/p-xylene mixture suggested that the selectivity for the benzene/p-xylene mixture appears at the pore mouths of FER on the feed side of the FER-alumina composite layer. © 1997 Elsevier Science B.V.

Zeolitic membranes were synthesized on a porous alumina support by the vapor-phase transport method using one of two alumina sources: aluminum sulfate and sodium aluminate. By choosing the appropriate period and temperature for drying the aluminosilicate gel on the alumina support, MOR, FER and MFI could be synthesized. MOR was formed when the water content in the dry gel was high. As the water content decreased, FER and MFI were formed sequentially. Preferential formation of MFI was achieved by treating the dry gel at 373 K. The temperature at which the support was dipped in the parent gel also influenced the type of zeolite formed, although the effect of drying conditions was more pronounced. A similar trend was found for both aluminum sulfate and sodium aluminate. When the alumina source was sodium aluminate and the aluminosilicate gel was treated at 373 K, a preferentially oriented MFI membrane could be synthesized, as the (a00) and (0b0) crystal faces were oriented in parallel to the surface of porous alumina support. The uniform and dense morphology of the dry gel seems to account for the appearance of the orientation. © 1997 Elsevier Science B.V.

Mordenite (MOR) and ferrierite (FER) membranes without any pinhole and crack were synthesized by a vapor-phase transport method. The permeance of H-2, He, CH4, N-2, O-2 and CO2 was determined at 290-400 K; which showed minimum with increasing temperatures for most cases. In the parallel diffusion model was proposed, molecules adsorbed in a micropore are assumed to diffuse in parallel through the central region of the pore and along the wall region of the pore. This parallel diffusion model accounts for the effect of pore Size of MOR and FER on the permeation and expresses the experimental data well. The interaction between gas molecules and pore walls are evaluated for each gas.

The mechanism of formation of ferrierite (FER) membrane on an alumina support by a vapor-phase transport (VPT) method was studied using XRD, SEM, FE-SEM and EDX. The XRD measurement for a FER membrane after the removal of FER particles formed on the support showed that FER was formed in the pores of the alumina support, namely, a FER-alumina composite layer was formed. The FE-SEM image for the cross-sectional view of the FER-alumina composite layer showed that FER nanocrystals of about 50 nm diameter grew in the pores of the alumina support. Pervaporation tests for benzene/p-xylene mixtures were performed at 303 K. Even when the concentration of benzene in the feed solution was extremely small (0.5 mol%), the flux of benzene through the FER membrane was still greater than that of p-xylene. Therefore, a separation factor as high as 600 was obtained in the low feed concentration of benzene. Such a high selectivity for the benzene/p-xylene mixture suggested that the selectivity for the benzene/p-xylene mixture appears at the pore mouths of FER on the feed side of the FER-alumina composite layer. © 1997 Elsevier Science B.V.

The value of pH for gel preparation has a significant influence on the compactness of a dry gel. A compact gel was prepared at high pH of ca. 12. An amorphous dry gel on a porous alumina support was crystallized by a vapor-phase transport (VPT) method. Membranes of low silica zeolites, analcime (ANA) and mordenite (MOR), were formed because alumina was partly dissolved and incorporated into the framework of zeolite. Coating of the alumina support with colloidal silica depressed the dissolution of alumina. On the alumina support coated with colloidal silica, ferrierite (FER) and ZSM-5 (MFI) membranes were obtained. Compactness of the MOR membrane was examined by a permeation test of 1,3,5-triisopropylbenzene (TIPB) at room temperature. Since no permeation of TIPB was detected, it was concluded that there existed no pinholes and cracks in the MOR membrane. The pervaporation test of a benzene/p-xylene mixture of which the molar ratio was 0.860, was carried out. The separation factor ((benzene/p-xylene)permeate/(benzene/p-xylene)feed) exceeded 160. Thus some shape selectivity appeared at the pore mouths of MOR. The formation process of the MOR membrane was studied by using SEM and XRD. The gel which penetrated in the alumina pores crystallized to MOR and formed a defect-free MOR-alumina composite layer.

The value of pH for gel preparation has a significant influence on the compactness of a dry gel. A compact gel was prepared at high pH of ca. 12. An amorphous dry gel on a porous alumina support was crystallized by a vapor-phase transport (VPT) method. Membranes of low silica zeolites, analcime (ANA) and mordenite (MOR), were formed because alumina was partly dissolved and incorporated into the framework of zeolite. Coating of the alumina support with colloidal silica depressed the dissolution of alumina. On the alumina support coated with colloidal silica, ferrierite (FER) and ZSM-5 (MFI) membranes were obtained. Compactness of the MOR membrane was examined by a permeation test of 1,3,5-triisopropylbenzene (TIPB) at room temperature. Since no permeation of TIPB was detected, it was concluded that there existed no pinholes and cracks in the MOR membrane. The pervaporation test of a benzene/p-xylene mixture of which the molar ratio was 0.860, was carried out. The separation factor ((benzene/p-xylene)permeate/(benzene/p-xylene)feed) exceeded 160. Thus some shape selectivity appeared at the pore mouths of MOR. The formation process of the MOR membrane was studied by using SEM and XRD. The gel which penetrated in the alumina pores crystallized to MOR and formed a defect-free MOR-alumina composite layer.

The value of pH for gel preparation has a significant influence on the compactness of a dry gel. A compact gel was prepared at high pH of ca. 12. An amorphous dry gel on a porous alumina support was crystallized by a vapor-phase transport (VPT) method. Membranes of low silica zeolites, analcime (ANA) and mordenite (MOR), were formed because alumina was partly dissolved and incorporated into the framework of zeolite. Coating of the alumina support with colloidal silica depressed the dissolution of alumina. On the alumina support coated with colloidal silica, ferrierite (FER) and ZSM-5 (MFI) membranes were obtained. Compactness of the MOR membrane was examined by a permeation test of 1,3,5-triisopropylbenzene (TIPB) at room temperature. Since no permeation of TIPB was detected, it was concluded that there existed no pinholes and cracks in the MOR membrane. The pervaporation test of a benzene/p-xylene mixture of which the molar ratio was 0.860, was carried out. The separation factor ((benzene/p-xylene)permeate/(benzene/p-xylene)feed) exceeded 160. Thus some shape selectivity appeared at the pore mouths of MOR. The formation process of the MOR membrane was studied by using SEM and XRD. The gel which penetrated in the alumina pores crystallized to MOR and formed a defect-free MOR-alumina composite layer.

Dry aluminosilicate gels were crystallized to MFI and FER by a vapor-phase transport (VPT) method using ethylenediamine (EDA), triethylamine (Et(3)N) and water as vapor sources. The roles of water and amines in this crystallization were investigated. While Et(3)N and water encouraged crystallization, EDA acted as a structure-directing agent. A dry gel was crystallized to FER when no water was added. The Al-27- and the Si-29-NMR spectra indicated that all Al atoms were incorporated into the zeolitic framework in the early stage of crystallization and that the rest of the Si-rich phase gradually crystallized. Full crystallization of Si and Al atoms in dry gel was possible by selecting optimum synthetic conditions. FER was transformed to MFI with prolonged crystallization. The structure and crystallinity of zeolite significantly depended on the sort of support on which the dry gel was placed.

Dry aluminosilicate gels were crystallized to MFI and FER by a vapor-phase transport (VPT) method using ethylenediamine (EDA), triethylamine (Et(3)N) and water as vapor sources. The roles of water and amines in this crystallization were investigated. While Et(3)N and water encouraged crystallization, EDA acted as a structure-directing agent. A dry gel was crystallized to FER when no water was added. The Al-27- and the Si-29-NMR spectra indicated that all Al atoms were incorporated into the zeolitic framework in the early stage of crystallization and that the rest of the Si-rich phase gradually crystallized. Full crystallization of Si and Al atoms in dry gel was possible by selecting optimum synthetic conditions. FER was transformed to MFI with prolonged crystallization. The structure and crystallinity of zeolite significantly depended on the sort of support on which the dry gel was placed.

A reformer using a circulating fluidized bed has been proposed for the production of hydrogen and syngas. A catalyst is circulated between two reactors for the catalytic decomposition of methane to hydrogen and carbon, and for the gasification of carbon deposited on the catalyst. Catalytic activities of Ni/SiO2 for both CH4 decomposition and CO2 gasification of deposited carbon were investigated at 873-1023 K in a periodically-operated fixed bed reactor. Carbon which had a moss-like morphology was hardly gasified and caused deactivation of the catalyst. Such a type of carbon became dominant with raising reaction temperature and with increasing amount of Ni loaded on SiO2. In contrast, filamentous carbon which had a graphitic structure could be gasified with CO2 and became dominant with decreasing amount of Ni loaded and with lowering reaction temperature. It was found that Ni(5 wt%)/SiO2 had a stable activity against the cycles of decomposition/gasification because Ni on Ni(5)/SiO2 was difficult to sinter at 873 K and as a result, the filamentous carbon was exclusively formed.

In order to analyze HCl and SO2 retention in fluidized bed combustors of coal and wastes, chlorination and sulphation of calcined limestone were investigated at 1023 K and atmospheric pressure using thermogravimetry. The rate of chlorination of calcined limestone slightly depended on its particle size and was kept almost constant against the progress of chlorination. In contrast, the rate of sulphation increased with decreasing particle size and steeply decreased with the progress of sulphation as commonly reported. It was found that the sulphation was markedly accelerated in the presence of HCl. Such acceleration of sulphation was remarkable for larger limestone. The level of conversion of CaO to (CaSO4 + CaCl2) always approached 100% in the simultaneous absorption of HCl and SO2. It was observed by SEM that in the chlorination a number of spherical aggregates and large voids were formed on the surface of limestone and that large aggregates with very flat surface and large voids have been formed in the course of the simultaneous chlorination and sulphation. These chlorination behavior and the acceleration of SO2 absorption in the presence of HCl can be due both to the formation of a mobile Cl- ion-containing phase and to the formation of voids playing a role of the diffusion paths for HCl and SO2 toward the interior of a limestone particle. Melting of a eutectic mixture of CaCl2 and CaSO4 might largely contribute to the promotion of SO2 absorption in the case of simultaneous absorption of HCl and SO2.

A reformer using a circulating fluidized bed has been proposed for the production of hydrogen and syngas. A catalyst is circulated between two reactors for the catalytic decomposition of methane to hydrogen and carbon, and for the gasification of carbon deposited on the catalyst. Catalytic activities of Ni/SiO2 for both CH4 decomposition and CO2 gasification of deposited carbon were investigated at 873-1023 K in a periodically-operated fixed bed reactor. Carbon which had a moss-like morphology was hardly gasified and caused deactivation of the catalyst. Such a type of carbon became dominant with raising reaction temperature and with increasing amount of Ni loaded on SiO2. In contrast, filamentous carbon which had a graphitic structure could be gasified with CO2 and became dominant with decreasing amount of Ni loaded and with lowering reaction temperature. It was found that Ni(5 wt%)/SiO2 had a stable activity against the cycles of decomposition/gasification because Ni on Ni(5)/SiO2 was difficult to sinter at 873 K and as a result, the filamentous carbon was exclusively formed.

Attempting to utilize natural zeolites as catalysts, characterization and modification of two kinds of those produced in Indonesia (Z1 and Z2) were carried out and their properties for hydrocracking of paraffins were evaluated using n-hexadecane as a petroleum model compound. The Z1 and Z2 samples were first treated with 6 N HCl at 90°C for 0.5 h or 20 h. X-Ray diffraction analysis of the HCl-treated samples (Z1-0.5 h, Z2-0.5 h, Z1-20 h, and Z2-20 h), as well as Z1 and Z2, indicated that both original samples mainly consist of mordenite type crystalline matter and the acid treatment removes some of crystalline impurities X-Ray fluorescence data revealed that Z1 and Z2 have Si/Al ratios of 4.3 and 3.1, respectively, and the treatment increases the ratio by dealumination as expected. The examination of hydrocracking properties showed that Z1 and Z2 have similar catalytic properties and the acid treatment considerably improves their activities. On the other hand, Z1- and Z2-20 h were less active than were Z1- and Z2-0.5 h, respectively. NH3-TPD and 29Si MAS NMR suggested that this may be due to the significant decrease of active acid sites by the prolonged treatment. It was also found that the loading of a small amount of nickel (0.8 wt%) onto Z1-0.5 h by ion exchange, significantly improves the catalytic property
the conversion of the paraffin was comparable with that using a synthetic H-mordenite.

In order to analyze HCl and SO2 retention in fluidized bed combustors of coal and wastes, chlorination and sulphation of calcined limestone were investigated at 1023 K and atmospheric pressure using thermogravimetry. The rate of chlorination of calcined limestone slightly depended on its particle size and was kept almost constant against the progress of chlorination. In contrast, the rate of sulphation increased with decreasing particle size and steeply decreased with the progress of sulphation as commonly reported. It was found that the sulphation was markedly accelerated in the presence of HCl. Such acceleration of sulphation was remarkable for larger limestone. The level of conversion of CaO to (CaSO4 + CaCl2) always approached 100% in the simultaneous absorption of HCl and SO2. It was observed by SEM that in the chlorination a number of spherical aggregates and large voids were formed on the surface of limestone and that large aggregates with very flat surface and large voids have been formed in the course of the simultaneous chlorination and sulphation. These chlorination behavior and the acceleration of SO2 absorption in the presence of HCl can be due both to the formation of a mobile Cl- ion-containing phase and to the formation of voids playing a role of the diffusion paths for HCl and SO2 toward the interior of a limestone particle. Melting of a eutectic mixture of CaCl2 and CaSO4 might largely contribute to the promotion of SO2 absorption in the case of simultaneous absorption of HCl and SO2.

A reformer using a circulating fluidized bed has been proposed for the production of hydrogen and syngas. A catalyst is circulated between two reactors for the catalytic decomposition of methane to hydrogen and carbon, and for the gasification of carbon deposited on the catalyst. Catalytic activities of Ni/SiO2 for both CH4 decomposition and CO2 gasification of deposited carbon were investigated at 873-1023 K in a periodically-operated fixed bed reactor. Carbon which had a moss-like morphology was hardly gasified and caused deactivation of the catalyst. Such a type of carbon became dominant with raising reaction temperature and with increasing amount of Ni loaded on SiO2. In contrast, filamentous carbon which had a graphitic structure could be gasified with CO2 and became dominant with decreasing amount of Ni loaded and with lowering reaction temperature. It was found that Ni(5 wt%)/SiO2 had a stable activity against the cycles of decomposition/gasification because Ni on Ni(5)/SiO2 was difficult to sinter at 873 K and as a result, the filamentous carbon was exclusively formed.

Attempting to utilize natural zeolites as catalysts, characterization and modification of two kinds of those produced in Indonesia (Z1 and Z2) were carried out and their properties for hydrocracking of paraffins were evaluated using n-hexadecane as a petroleum model compound. The Z1 and Z2 samples were first treated with 6 N HCl at 90°C for 0.5 h or 20 h. X-Ray diffraction analysis of the HCl-treated samples (Z1-0.5 h, Z2-0.5 h, Z1-20 h, and Z2-20 h), as well as Z1 and Z2, indicated that both original samples mainly consist of mordenite type crystalline matter and the acid treatment removes some of crystalline impurities X-Ray fluorescence data revealed that Z1 and Z2 have Si/Al ratios of 4.3 and 3.1, respectively, and the treatment increases the ratio by dealumination as expected. The examination of hydrocracking properties showed that Z1 and Z2 have similar catalytic properties and the acid treatment considerably improves their activities. On the other hand, Z1- and Z2-20 h were less active than were Z1- and Z2-0.5 h, respectively. NH3-TPD and 29Si MAS NMR suggested that this may be due to the significant decrease of active acid sites by the prolonged treatment. It was also found that the loading of a small amount of nickel (0.8 wt%) onto Z1-0.5 h by ion exchange, significantly improves the catalytic property
the conversion of the paraffin was comparable with that using a synthetic H-mordenite.

A methane reformer using a circulating fluidized bed is proposed for the production of hydrogen and synthesis gas (syngas). A catalyst is circulated between two reactors for the catalytic decomposition of methane to hydrogen and carbon and for the gasification of the carbon deposited on the catalyst. Of the metals Cu, Fe, Ni, and W, only Ni showed catalytic activity for the decomposition of methane at 873-1023 K. While studying the structure of the catalyst, it was found that the form of nickel was circulated between oxide and metal through reduction with methane and oxidation with carbon dioxide. X-ray diffraction (XRD) and scanning electron microscopy (SEM) suggested that filamentous carbon having a graphitic structure was gasified with carbon dioxide and that carbon having a mosslike morphology was hardly gasified and caused deactivation of the catalyst. The reactivity of the carbon which was able to be gasified was not altered with cycles of methane decomposition and carbon dioxide gasification.

A methane reformer using a circulating fluidized bed is proposed for the production of hydrogen and synthesis gas (syngas). A catalyst is circulated between two reactors for the catalytic decomposition of methane to hydrogen and carbon and for the gasification of the carbon deposited on the catalyst. Of the metals Cu, Fe, Ni, and W, only Ni showed catalytic activity for the decomposition of methane at 873-1023 K. While studying the structure of the catalyst, it was found that the form of nickel was circulated between oxide and metal through reduction with methane and oxidation with carbon dioxide. X-ray diffraction (XRD) and scanning electron microscopy (SEM) suggested that filamentous carbon having a graphitic structure was gasified with carbon dioxide and that carbon having a mosslike morphology was hardly gasified and caused deactivation of the catalyst. The reactivity of the carbon which was able to be gasified was not altered with cycles of methane decomposition and carbon dioxide gasification.

Effluent from the FCC process contains considerable concentrations of phenol, sulfide and ammonium ions. The pH of the effluent is around 9. In the present study, the possibility of the application of anion exchange membranes for its removal and recovery, was investigated. The equilibrium constant between phenol and hydroxide ions and the ion exchange capacity of a commercial anion exchange membrane were determined. The membrane was sandwiched between two glass cells filled with a phenol solution at pH 9, fed and withdrawn continuously to keep the phenol concentration constant, and a sodium hydroxide solution at various pH, respectively. The permeation rate increased with pH and reached a plateau at above pH 13. The permeation rate was measured for various concentrations of phenol in the feed side, keeping the pH of the strip side at 13. The rate linearly increased with the phenol concentration and reached a plateau at concentration greater than 1 mol/m3. The apparent diffusion coefficient of phenol in the membrane was determined from the plateau value. At a concentration of less than 1 mol/m3, the rate was found to be controlled by boundary film resistance. It was also found that the permeation rate of phenol was suppressed by the sulfide ion at a concentration comparable to or larger than that of phenol. © 1995.

Effluent from the FCC process contains considerable concentrations of phenol, sulfide and ammonium ions. The pH of the effluent is around 9. In the present study, the possibility of the application of anion exchange membranes for its removal and recovery, was investigated. The equilibrium constant between phenol and hydroxide ions and the ion exchange capacity of a commercial anion exchange membrane were determined. The membrane was sandwiched between two glass cells filled with a phenol solution at pH 9, fed and withdrawn continuously to keep the phenol concentration constant, and a sodium hydroxide solution at various pH, respectively. The permeation rate increased with pH and reached a plateau at above pH 13. The permeation rate was measured for various concentrations of phenol in the feed side, keeping the pH of the strip side at 13. The rate linearly increased with the phenol concentration and reached a plateau at concentration greater than 1 mol/m3. The apparent diffusion coefficient of phenol in the membrane was determined from the plateau value. At a concentration of less than 1 mol/m3, the rate was found to be controlled by boundary film resistance. It was also found that the permeation rate of phenol was suppressed by the sulfide ion at a concentration comparable to or larger than that of phenol. © 1995.

The effects of gasification conditions, namely bed temperature, static bed height, and nozzle diameter, on the concentrations of H-2, CO, and CO2 were investigated using a batchwise fluidized bed gasifier of coal char. Gas concentration profiles in the bed could be explained by the production of gases chiefly via combustion, steam gasification, CO2 gasification, and the diffusion of produced gases. The temperature dependence of gas concentrations indicates that steam gasification occurred in the lower part of the grid zone at a higher bed temperature and the selectivity of CO production via combustion in the boundary region of the jet and annulus also increased. The results of the effect of static bed height suggest that CO2 gasification mainly proceeded in the bubbling zone and the local reactions in the grid zone were hardly influenced by gas and solid behavior or reactions in the upper part of the bed. Though the diameter and height of the jet would be dependent on nozzle diameter, the effect of nozzle diameter on the local progress of gasification in the grid zone was hardly observed. It can be concluded that gasification proceeded in both the bubbling zone and annulus region, especially near the distributor, while combustion mainly occurred in the jet and boundary of the jet and annulus.

The effects of gasification conditions, namely bed temperature, static bed height, and nozzle diameter, on the concentrations of H-2, CO, and CO2 were investigated using a batchwise fluidized bed gasifier of coal char. Gas concentration profiles in the bed could be explained by the production of gases chiefly via combustion, steam gasification, CO2 gasification, and the diffusion of produced gases. The temperature dependence of gas concentrations indicates that steam gasification occurred in the lower part of the grid zone at a higher bed temperature and the selectivity of CO production via combustion in the boundary region of the jet and annulus also increased. The results of the effect of static bed height suggest that CO2 gasification mainly proceeded in the bubbling zone and the local reactions in the grid zone were hardly influenced by gas and solid behavior or reactions in the upper part of the bed. Though the diameter and height of the jet would be dependent on nozzle diameter, the effect of nozzle diameter on the local progress of gasification in the grid zone was hardly observed. It can be concluded that gasification proceeded in both the bubbling zone and annulus region, especially near the distributor, while combustion mainly occurred in the jet and boundary of the jet and annulus.

The local behavior of gas and solids in a grid zone was investigated using a jetting fluidized bed cold model. Spherical alumina particles (440 μm, 1500 kg/m3) were used as bed material. A pair of optical fiber sensors, an A D converter and a personal computer were used to measure particle velocity in the jet, jet diameter and jet height. Tracer gas introduced from a center nozzle was sampled from various points in the grid zone and its concentration was measured by gas chromatography to investigate gas interchange between the jet and the annulus, and the gas dispersion in the annulus region. The effects of operational conditions, i.e., the shape of the gas distributor, nozzle diameter and gas flow rates, on the gas and particle behavior are discussed. It was considered that many more particles entered into the jet when a cone-shaped distributor rather than a flat distributor was employed. Employment of a narrower nozzle caused an increase in particle velocity at the bottom of the bed. © 1995.

A defect-free MOR membrane is synthesized on a porous alumina plate by a vapour phase transport method: shape selectivity is apparent in the pervaporation of a benzene-p-xylene mixture (the separation factor exceeded 160).

Selective permeation of vanadium(V) and chromium(VI) using three types of membrane systems was studied. The first was an anion exchange membrane, the second and third were supported liquid membranes containing either a tertiary amine or a quaternary ammonium salt. The membrane was sandwiched between two glass cells. One cell was filled with a solution of identical concentrations of vanadium(V) and chromium(VI), and the other cell contained sodium hydroxide solution. The permeation rates of vanadium(V) and chromium(VI) were measured from the concentration change in the solution on the recovery side of the membrane. The selectivity of vanadium(V) over chromium(VI) was defined as the ratio of their rates. The selectivity of vanadium(V) over chromium(VI) was as high as 10 for pH of feed phase between 8 and 10 when using the quaternary ammonium salt and much better than these for the other membranes with an alkaline feed phase, which was used to simulate of the effluent from leaching of the heavy oil combustion ash and other wastes containing vanadium. Copyright © 1995 Publisher John Wiley &amp
Sons, Ltd.

The local behavior of gas and solids in a grid zone was investigated using a jetting fluidized bed cold model. Spherical alumina particles (440 μm, 1500 kg/m3) were used as bed material. A pair of optical fiber sensors, an A D converter and a personal computer were used to measure particle velocity in the jet, jet diameter and jet height. Tracer gas introduced from a center nozzle was sampled from various points in the grid zone and its concentration was measured by gas chromatography to investigate gas interchange between the jet and the annulus, and the gas dispersion in the annulus region. The effects of operational conditions, i.e., the shape of the gas distributor, nozzle diameter and gas flow rates, on the gas and particle behavior are discussed. It was considered that many more particles entered into the jet when a cone-shaped distributor rather than a flat distributor was employed. Employment of a narrower nozzle caused an increase in particle velocity at the bottom of the bed. © 1995.

A defect-free MOR membrane is synthesized on a porous alumina plate by a vapour phase transport method: shape selectivity is apparent in the pervaporation of a benzene-p-xylene mixture (the separation factor exceeded 160).

Selective permeation of vanadium(V) and chromium(VI) using three types of membrane systems was studied. The first was an anion exchange membrane, the second and third were supported liquid membranes containing either a tertiary amine or a quaternary ammonium salt. The membrane was sandwiched between two glass cells. One cell was filled with a solution of identical concentrations of vanadium(V) and chromium(VI), and the other cell contained sodium hydroxide solution. The permeation rates of vanadium(V) and chromium(VI) were measured from the concentration change in the solution on the recovery side of the membrane. The selectivity of vanadium(V) over chromium(VI) was defined as the ratio of their rates. The selectivity of vanadium(V) over chromium(VI) was as high as 10 for pH of feed phase between 8 and 10 when using the quaternary ammonium salt and much better than these for the other membranes with an alkaline feed phase, which was used to simulate of the effluent from leaching of the heavy oil combustion ash and other wastes containing vanadium. Copyright © 1995 Publisher John Wiley &amp
Sons, Ltd.

A thin zeolitic membrane on porous alumina support has been synthesized
the permeability of the film to N2 and O2 indicated that the membrane was formed in a compact form.

Vapor-phase oxidative acetoxylation of toluene on Pd-based bimetallic catalysts was investigated. The main products were benzylacetate, produced via side-chain acetoxylation, and CO and CO2 resulted from combustion. Nuclear acetoxylation hardly occurred. A K-doped Pd-Au/SiO2 gave the highest activity and selectivity for synthesis of benzylacetate among the catalysts tested
the yield of benzylacetate on the K-doped Pd-Au/SiO2 was about 150 times greater than that on a Pd/SiO2. It was found that the addition of an adequate amount of Au to Pd/SiO2 inhibited the formation of CO2, and that potassium species worked as sites for adsorption and activation of acetic acid. © 1994, The Japan Petroleum Institute. All rights reserved.

The synthesis method to obtain a tight and thin zeolitic membrane was investigated. It was found that the most important factor to prepare a zeolitic membrane in a compact form was the pH to prepare the parent aluminosilicate gel. The aluminosilicate gel was supported on a porous alumina plate and treated in the vapor of templating reagents. It was found that a thin layer of ferrierite was formed on the surface of the plate. The rates of permeation of H-2, He, CH4, O-2, N-2 and CO2 through the ferrierite membrane were measured. Permeation results indicated that the ferrierite membrane is formed in a compact form.

We developed a fluidized bed-chemical vapor deposition (CVD) reactor for a novel method of particle processing, such as particle coating and surface treatment. Microwave plasma was applied as an excitation source of reactive gases, and alumina and silicon were used as bed materials. The hydrodynamic behavior of the plasma-bubbling fluidized bed was studied and the field of plasma generation was investigated optically. Only minor plasma generation was noted in the dense phase. Plasma emission was observed in most of the bubbles in the alumina-fluidized bed, while plasma generated at the surface of the silicon-fluidized bed where bubbles splashed. Methane conversion was carried out in the alumina-fluidized bed as a model reaction. Although excitation of methane occurred in bubbles, excited species entered into the dense phase from bubbles and were effectively converted to carbon on the surface of the particles. Thus, heterogenous CVD on the surface of particles may occur in this reactor. © 1994.

A thin zeolitic membrane on porous alumina support has been synthesized
the permeability of the film to N2 and O2 indicated that the membrane was formed in a compact form.

Vapor-phase oxidative acetoxylation of toluene on Pd-based bimetallic catalysts was investigated. The main products were benzylacetate, produced via side-chain acetoxylation, and CO and CO2 resulted from combustion. Nuclear acetoxylation hardly occurred. A K-doped Pd-Au/SiO2 gave the highest activity and selectivity for synthesis of benzylacetate among the catalysts tested
the yield of benzylacetate on the K-doped Pd-Au/SiO2 was about 150 times greater than that on a Pd/SiO2. It was found that the addition of an adequate amount of Au to Pd/SiO2 inhibited the formation of CO2, and that potassium species worked as sites for adsorption and activation of acetic acid. © 1994, The Japan Petroleum Institute. All rights reserved.

The synthesis method to obtain a tight and thin zeolitic membrane was investigated. It was found that the most important factor to prepare a zeolitic membrane in a compact form was the pH to prepare the parent aluminosilicate gel. The aluminosilicate gel was supported on a porous alumina plate and treated in the vapor of templating reagents. It was found that a thin layer of ferrierite was formed on the surface of the plate. The rates of permeation of H-2, He, CH4, O-2, N-2 and CO2 through the ferrierite membrane were measured. Permeation results indicated that the ferrierite membrane is formed in a compact form.

We developed a fluidized bed-chemical vapor deposition (CVD) reactor for a novel method of particle processing, such as particle coating and surface treatment. Microwave plasma was applied as an excitation source of reactive gases, and alumina and silicon were used as bed materials. The hydrodynamic behavior of the plasma-bubbling fluidized bed was studied and the field of plasma generation was investigated optically. Only minor plasma generation was noted in the dense phase. Plasma emission was observed in most of the bubbles in the alumina-fluidized bed, while plasma generated at the surface of the silicon-fluidized bed where bubbles splashed. Methane conversion was carried out in the alumina-fluidized bed as a model reaction. Although excitation of methane occurred in bubbles, excited species entered into the dense phase from bubbles and were effectively converted to carbon on the surface of the particles. Thus, heterogenous CVD on the surface of particles may occur in this reactor. © 1994.

A new system to measure very short bubble coalescence time was developed using a laser. The system's reliability was confirmed by comparing the system output with photographic observation by high-speed video camera. The result for aqueous solutions of n-alcohol was in good agreement with the previous data. The system was applied to various kinds of aqueous solutions more dilute than those in previous work where the value of bubble coalescence time was expected to be less than 2 ms. It was revealed that the bubble coalescence time reported in previous work was composed of two parts. The first part was the time length of the contacting period of two bubbles and the second was the time length of the initial stage of a film rupture between the bubbles. The former decreased considerably, even to an undetectably small value, with decrease in concentration, but the latter was constantly at about 0.3 ms regardless of concentration. Effects of bubble age and bubble approach velocity were examined. It was also found that the bubble coalescence time in surfactant solution was significantly influenced in a narrow concentration region as low as ppb order and that the bubbles did not coalesce in solution of higher concentration.

A new system to measure very short bubble coalescence time was developed using a laser. The system's reliability was confirmed by comparing the system output with photographic observation by high-speed video camera. The result for aqueous solutions of n-alcohol was in good agreement with the previous data. The system was applied to various kinds of aqueous solutions more dilute than those in previous work where the value of bubble coalescence time was expected to be less than 2 ms. It was revealed that the bubble coalescence time reported in previous work was composed of two parts. The first part was the time length of the contacting period of two bubbles and the second was the time length of the initial stage of a film rupture between the bubbles. The former decreased considerably, even to an undetectably small value, with decrease in concentration, but the latter was constantly at about 0.3 ms regardless of concentration. Effects of bubble age and bubble approach velocity were examined. It was also found that the bubble coalescence time in surfactant solution was significantly influenced in a narrow concentration region as low as ppb order and that the bubbles did not coalesce in solution of higher concentration.

The present study found that aluminosilicate gels were crystallized to ZSM-5, ferrierite, KZ-2 or analcime under a vapor atmosphere. The structure and crystallinity of the resultant zeolite significantly depended on the composition of the organic vapor as well as that of the parent gel. © 1993.

Local concentrations of gases in the jetting fluidized bed coal gasifier, particularly in the grid zone of the bed were measured to discuss gas exchange between the jet and annulus and local progress of chemical reactions. Air was introduced from the gas injection nozzle and steam was introduced from the coneshaped distributor plate. Gas exchange between the annulus and the jet rapidly occurred. Compared with the case that only steam was introduced, it was found that air introduced from the nozzle produced carbon oxides at around the boundary of the jet and as a result decreased the rate of steam gasification in the annulus. Both for physical and chemical phenomena the grid zone cannot be regarded as uniform. The grid structure strongly influenced the performance of the gasifier. © 1993.

Oxidative acetoxylation of toluene and benzene using molecular oxygen was carried out over supported palladium catalysts in the temperature range of 453-493 K at atmospheric pressure. It was found that the addition of gold on silica-supported palladium promoted acetoxylation of toluene and benzene. © 1993, The Japan Petroleum Institute. All rights reserved.

Dynamic light scattering (DLS) based on a monodisperse model was applied to ultrafine particle formation in a flame where particles grow and deform within several ms, with occasional high number density and broad size distribution. DLS was experimentally evaluated as an in-situ technique of measuring mean particle size by comparing with TEM (transmission electron microscope) photographs. The following results were obtained. 1. For particles formed in a flame, a mean particle size of several tens of nanometers by DLS with monodisperse assumption was in good agreement with the volume mean diameter obtained from TEM photographs, except for particles strongly deviated to small size. 2. For particles with a size distribution strongly deviated to the fine side, DLS with monodisperse assumption gives a considerably large value, around twice the volume mean diameter. This value still reflects a plausible mean size of large particles contained in the measuring volume. © 1993, The Society of Chemical Engineers, Japan. All rights reserved.

The present study found that aluminosilicate gels were crystallized to ZSM-5, ferrierite, KZ-2 or analcime under a vapor atmosphere. The structure and crystallinity of the resultant zeolite significantly depended on the composition of the organic vapor as well as that of the parent gel. © 1993.

Local concentrations of gases in the jetting fluidized bed coal gasifier, particularly in the grid zone of the bed were measured to discuss gas exchange between the jet and annulus and local progress of chemical reactions. Air was introduced from the gas injection nozzle and steam was introduced from the coneshaped distributor plate. Gas exchange between the annulus and the jet rapidly occurred. Compared with the case that only steam was introduced, it was found that air introduced from the nozzle produced carbon oxides at around the boundary of the jet and as a result decreased the rate of steam gasification in the annulus. Both for physical and chemical phenomena the grid zone cannot be regarded as uniform. The grid structure strongly influenced the performance of the gasifier. © 1993.

Oxidative acetoxylation of toluene and benzene using molecular oxygen was carried out over supported palladium catalysts in the temperature range of 453-493 K at atmospheric pressure. It was found that the addition of gold on silica-supported palladium promoted acetoxylation of toluene and benzene. © 1993, The Japan Petroleum Institute. All rights reserved.

Dynamic light scattering (DLS) based on a monodisperse model was applied to ultrafine particle formation in a flame where particles grow and deform within several ms, with occasional high number density and broad size distribution. DLS was experimentally evaluated as an in-situ technique of measuring mean particle size by comparing with TEM (transmission electron microscope) photographs. The following results were obtained. 1. For particles formed in a flame, a mean particle size of several tens of nanometers by DLS with monodisperse assumption was in good agreement with the volume mean diameter obtained from TEM photographs, except for particles strongly deviated to small size. 2. For particles with a size distribution strongly deviated to the fine side, DLS with monodisperse assumption gives a considerably large value, around twice the volume mean diameter. This value still reflects a plausible mean size of large particles contained in the measuring volume. © 1993, The Society of Chemical Engineers, Japan. All rights reserved.

The variations in the amounts of alkali and alkaline earth species actually existing on the surface of carbon black in the courses of heat treatment up to 1123 K and steam gasification at 1073 K were investigated, in order to understand the actual amount of catalyst existing on the surface of carbon in the working state. These gasification catalysts were classified into three groups based on the fact that some of them sunk into the bulk of carbon in the course of heat treatment and some of them vaporized from the surface of carbon. It was found that the migration of species into the bulk of carbon was profoundly associated with the reducibility of their oxide state.

The variations in the amounts of alkali and alkaline earth species actually existing on the surface of carbon black in the courses of heat treatment up to 1123 K and steam gasification at 1073 K were investigated, in order to understand the actual amount of catalyst existing on the surface of carbon in the working state. These gasification catalysts were classified into three groups based on the fact that some of them sunk into the bulk of carbon in the course of heat treatment and some of them vaporized from the surface of carbon. It was found that the migration of species into the bulk of carbon was profoundly associated with the reducibility of their oxide state.

The mobility of alkali and alkaline earth elements loaded on carbon black during heat treatment up to 1123 K in an inert atmosphere was investigated by different spectroscopic methods. The objective was to improve our understanding of gasification by catalysts containing these elements. It was found that Na, Rb, Cs, Sr and Li species migrated into the bulk of carbon on heating up to 1123 K in a flowing inert atmosphere.

The mobility of alkali and alkaline earth elements loaded on carbon black during heat treatment up to 1123 K in an inert atmosphere was investigated by different spectroscopic methods. The objective was to improve our understanding of gasification by catalysts containing these elements. It was found that Na, Rb, Cs, Sr and Li species migrated into the bulk of carbon on heating up to 1123 K in a flowing inert atmosphere.

It has been pointed out that polycrystalline silicon particles produced from monosilane by the fluidized-bed CVD method contain residual hydrogen that causes disturbance of flow in a crucible in the CZ process. In the present work, the residual hydrogen was desorbed from produced Si particles by heat treatment. The activation energy for the hydrogen desorption was determined by the temperature-programmed desorption (TPD) technique. By FTIR, various types of Si-H bonds were found in the Si particles produced. The adsorbance area was decreased with increase in the desorbed hydrogen by TPD. From this relationship, the total amount of residual hydrogen was determined to be around 0.05% of the hydrogen contained in the reacted monosilane. The particle density of Si particles increased linearly almost up to the true density, with a decrease in the absorbance area of FTIR by the heat treatment.

A plasma jetting fluidized bed reactor was developed for coating particles via PCVD. Conversion of methane was carried out to investigate characteristics of this type of reactor. It was found that introduction of reactive gases from the side of a d.c. plasma jet resulted in no deterioration of the stability of plasma and that the reactive gases were effectively activated even in the presence of particles. Particles packed in the reactor promoted reactions to give carbon in the presence of hydrogen in a large excess, strongly suggesting that PCVD on fluidized particles can be realized.

Characterization of polycrystalline silicon particles produced in a fluidized bed reactor via CVD from monosilane was carried out. It was observed that part of the hydrogen from monosilane remained in the particles. Most of hydrogen was bonded to silicon and temperatures as high as 1300 K were required to dehydrogenate the silicon particles. Particles were contaminated with metal elements which were diffused from the reactor wall, suggesting that the material used in constructing the fluidized bed reactor wall also needed to be controlled to improve the purity of product.

A plasma jetting fluidized bed reactor was developed for coating particles via PCVD. Conversion of methane was carried out to investigate characteristics of this type of reactor. It was found that introduction of reactive gases from the side of a d.c. plasma jet resulted in no deterioration of the stability of plasma and that the reactive gases were effectively activated even in the presence of particles. Particles packed in the reactor promoted reactions to give carbon in the presence of hydrogen in a large excess, strongly suggesting that PCVD on fluidized particles can be realized.

Characterization of polycrystalline silicon particles produced in a fluidized bed reactor via CVD from monosilane was carried out. It was observed that part of the hydrogen from monosilane remained in the particles. Most of hydrogen was bonded to silicon and temperatures as high as 1300 K were required to dehydrogenate the silicon particles. Particles were contaminated with metal elements which were diffused from the reactor wall, suggesting that the material used in constructing the fluidized bed reactor wall also needed to be controlled to improve the purity of product.

The benzene-steam reaction on MgO doped with Ca, Sr, Ba, and K was investigated at 1,173K and at atmospheric pressure to understand the action of steam as gasifying reagent in hydrocarbon gasification. The results were discussed by comparing with those of the benzene-CO2reaction. The benzene-steam reaction was proposed to proceed via the decomposition of benzene to give an intermediate carbon and subsequent gasification of the carbon. The steam adsorbed on the catalyst was found to hinder the decomposition of benzene to give the intermediate. Catalytic activity for the benzene-steam reaction could be interpreted mainly by a combination of catalytic activity for gasification of deposited carbon and the degree of hindrance to the decomposition of benzene by adsorbed steam. The mobility of catalytic species in the layers of the deposited carbon was found to be an important factor governing the rate of gasification of the deposited carbon. © 1991, The Japanese Association of Educational Psychology. All rights reserved.

The benzene-oxygen reaction catalyzed by alkaline earth metal oxides was investigated in the temperature range 773-1,073K to understand the catalytic function of these oxides for hydrocarbon gasification. In the initial stage of reaction, CO, CO2, H2O, and biphenyl were concurrently produced. The consumption of CO and H2O by the water-gas shift reaction subsequently occurred to give CO2and H2. CO oxidation with O2hardly occurred in the course of the benzene-oxygen reaction because benzene was preferentially adsorbed on the MgO catalyst. These reaction sequences were compared with those in the benzene-oxygen reaction catalyzed by metallic nickel. © 1991, The Japanese Association of Educational Psychology. All rights reserved.

The benzene-steam reaction on MgO doped with Ca, Sr, Ba, and K was investigated at 1,173K and at atmospheric pressure to understand the action of steam as gasifying reagent in hydrocarbon gasification. The results were discussed by comparing with those of the benzene-CO2reaction. The benzene-steam reaction was proposed to proceed via the decomposition of benzene to give an intermediate carbon and subsequent gasification of the carbon. The steam adsorbed on the catalyst was found to hinder the decomposition of benzene to give the intermediate. Catalytic activity for the benzene-steam reaction could be interpreted mainly by a combination of catalytic activity for gasification of deposited carbon and the degree of hindrance to the decomposition of benzene by adsorbed steam. The mobility of catalytic species in the layers of the deposited carbon was found to be an important factor governing the rate of gasification of the deposited carbon. © 1991, The Japanese Association of Educational Psychology. All rights reserved.

The benzene-oxygen reaction catalyzed by alkaline earth metal oxides was investigated in the temperature range 773-1,073K to understand the catalytic function of these oxides for hydrocarbon gasification. In the initial stage of reaction, CO, CO2, H2O, and biphenyl were concurrently produced. The consumption of CO and H2O by the water-gas shift reaction subsequently occurred to give CO2and H2. CO oxidation with O2hardly occurred in the course of the benzene-oxygen reaction because benzene was preferentially adsorbed on the MgO catalyst. These reaction sequences were compared with those in the benzene-oxygen reaction catalyzed by metallic nickel. © 1991, The Japanese Association of Educational Psychology. All rights reserved.

In order to investigate the mobility and structural change of barium and calcium compounds loaded on carbon substrate in the courses of heat treatment and of gasification, AES and EPMA were employed to observe the surface structure of amorphous carbon black impregnated by barium or calcium nitrate. We found that barium species migrated into the bulk of carbon in the course of heat treatment up to 1123 K, while calcium species did not. The difference in mobility between barium and calcium species is due to the difference in the reducibility of these cations by the action of carbon in the course of heat treatment. Mineral matter was concentrated at the surface of carbon during gasification and reacted with BaCO3 to disperse in the interior of BaCO3 particles on the carbon surface. On the other hand, sulfur was found on the BaCO3 surface under gasification conditions. © 1990, American Chemical Society. All rights reserved.

In order to investigate the mobility and structural change of barium and calcium compounds loaded on carbon substrate in the courses of heat treatment and of gasification, AES and EPMA were employed to observe the surface structure of amorphous carbon black impregnated by barium or calcium nitrate. We found that barium species migrated into the bulk of carbon in the course of heat treatment up to 1123 K, while calcium species did not. The difference in mobility between barium and calcium species is due to the difference in the reducibility of these cations by the action of carbon in the course of heat treatment. Mineral matter was concentrated at the surface of carbon during gasification and reacted with BaCO3 to disperse in the interior of BaCO3 particles on the carbon surface. On the other hand, sulfur was found on the BaCO3 surface under gasification conditions. © 1990, American Chemical Society. All rights reserved.

Ca2+ ions loaded on MgO surface markedly promoted catalytic activities of MgO for isomerization of 1-butene, hydrocarbon gasification with CO2 or O2, and the reverse water-gas shift reaction, although MgO itself was almost inactive after treatment at 1273K in air. Ca2+ ions also increased the basicity and basic strength of MgO. Strong basic sites catalyzed isomerization of 1-butene. In the course of impregnation with Ca(NO3)2, MgO (periclase) was completely transformed into hydrate (brucite) by the action of nitrate ions. It is considered that Ca2+ ions interfere with the transformation of surface arrangements accompanied with structural transformation from brucite (hcp) to periclase (fcc). It wasm found that most of Ca2+ ions aggregated to form particles of CaO on the surface of MgO while Ca2+ ions were highly dispersed on the surface of MgO when the MgO was prepared from basic carbonate salt involving calcium as an impurity. © 1989, The Japan Petroleum Institute. All rights reserved.

The benzene-carbon dioxide reaction was performed over alkaline earth metal oxide catalysts at temperatures in the range 973-1173K to investigate the reaction sequence in hydrocarbon gasification and the catalytic role of these oxides. To discuss the difference in the reactivities of benzene and hexane, we propose a reaction scheme as follows: the reaction proceeds via the intermediate carbon deposited by direct decomposition of benzene on the surface of the catalyst producing hydrogen simultaneously, and the rapid reverse water gas shift reaction concurrently occurs to give carbon monoxide and steam in equilibrium composition. The catalytic activity was determined on the balance between the rate of formation of intermediate carbon and the rate of its gasification. Characterization of catalysts by means of 1-butene isomerization leads to a confirmation that carbon accumulates on an inactive part of the catalyst surface. © 1989, The Japan Petroleum Institute. All rights reserved.

Ca2+ ions loaded on MgO surface markedly promoted catalytic activities of MgO for isomerization of 1-butene, hydrocarbon gasification with CO2 or O2, and the reverse water-gas shift reaction, although MgO itself was almost inactive after treatment at 1273K in air. Ca2+ ions also increased the basicity and basic strength of MgO. Strong basic sites catalyzed isomerization of 1-butene. In the course of impregnation with Ca(NO3)2, MgO (periclase) was completely transformed into hydrate (brucite) by the action of nitrate ions. It is considered that Ca2+ ions interfere with the transformation of surface arrangements accompanied with structural transformation from brucite (hcp) to periclase (fcc). It wasm found that most of Ca2+ ions aggregated to form particles of CaO on the surface of MgO while Ca2+ ions were highly dispersed on the surface of MgO when the MgO was prepared from basic carbonate salt involving calcium as an impurity. © 1989, The Japan Petroleum Institute. All rights reserved.

The benzene-carbon dioxide reaction was performed over alkaline earth metal oxide catalysts at temperatures in the range 973-1173K to investigate the reaction sequence in hydrocarbon gasification and the catalytic role of these oxides. To discuss the difference in the reactivities of benzene and hexane, we propose a reaction scheme as follows: the reaction proceeds via the intermediate carbon deposited by direct decomposition of benzene on the surface of the catalyst producing hydrogen simultaneously, and the rapid reverse water gas shift reaction concurrently occurs to give carbon monoxide and steam in equilibrium composition. The catalytic activity was determined on the balance between the rate of formation of intermediate carbon and the rate of its gasification. Characterization of catalysts by means of 1-butene isomerization leads to a confirmation that carbon accumulates on an inactive part of the catalyst surface. © 1989, The Japan Petroleum Institute. All rights reserved.

The catalytic properties of alkaline earth metal oxides and the reaction sequences in the hexane-carbon dioxide reaction were investigated at 1173 K and atmospheric pressure. The catalytic activity for the decomposition of hexane to give deposited carbon increased with increase in the surface area of the catalyst, but the order of the activity for gasification of the deposited carbon was not parallel with either that for the decomposition of hexane or that for the hexane-carbon dioxide reaction. The catalytic activity for the hexane-carbon dioxide reaction was determined from the balance between the activity for the decomposition of hexane to produce the intermediate and that for the gasification of the deposited intermediate carbon. An oxygen transfer mechanism was applied to explain the gasification of carbon deposited on the catalyst surface. It was also confirmed that alkaline earth metal oxides catalyze the water-gas shift reaction under the gasification conditions. Based on these results, a network for the hexane-carbon dioxide reaction is proposed in order to understand comprehensively the catalysis of these oxides. © 1988.

The catalytic properties of alkaline earth metal oxides and the reaction sequences in the hexane-carbon dioxide reaction were investigated at 1173 K and atmospheric pressure. The catalytic activity for the decomposition of hexane to give deposited carbon increased with increase in the surface area of the catalyst, but the order of the activity for gasification of the deposited carbon was not parallel with either that for the decomposition of hexane or that for the hexane-carbon dioxide reaction. The catalytic activity for the hexane-carbon dioxide reaction was determined from the balance between the activity for the decomposition of hexane to produce the intermediate and that for the gasification of the deposited intermediate carbon. An oxygen transfer mechanism was applied to explain the gasification of carbon deposited on the catalyst surface. It was also confirmed that alkaline earth metal oxides catalyze the water-gas shift reaction under the gasification conditions. Based on these results, a network for the hexane-carbon dioxide reaction is proposed in order to understand comprehensively the catalysis of these oxides. © 1988.

To produce town gas catalytic methanation of methanol was investigated in the temperature range of 300—350°C. Nickel and alumina were excellent components of the catalyst. The catalysts containing 80wt% of nickel prepared by coprecipitation methods showed especially high activities at 300°C. The methanol conversion over the coprecipitated catalysts was dependent upon the size of the nickel crystallite, while the methane selectivities were not. The activity and selectivity of coprecipitated catalysts were steady during a 20hr-run and on addition of water to methanol. © 1987, The Japan Petroleum Institute. All rights reserved.

To produce town gas catalytic methanation of methanol was investigated in the temperature range of 300—350°C. Nickel and alumina were excellent components of the catalyst. The catalysts containing 80wt% of nickel prepared by coprecipitation methods showed especially high activities at 300°C. The methanol conversion over the coprecipitated catalysts was dependent upon the size of the nickel crystallite, while the methane selectivities were not. The activity and selectivity of coprecipitated catalysts were steady during a 20hr-run and on addition of water to methanol. © 1987, The Japan Petroleum Institute. All rights reserved.

Steam reforming of atmospheric, vacuum and solvent-deasphalting residues was investigated using a fluidized bed reactor, where alumina-supported potassium and calcium oxide catalysts were packed. Atmospheric residues were gasified with high efficiency on GaO above 850°C. The catalytic activity, however, decreased markedly with increasing Conradson carbon residue (CGR) of the feed residues. On the other hand, high activity of potassium catalyst was attained even in the gasification of very heavy residues from solvent deasphalting. The decrease in catalytic activity of CaO was not due to sulfur-poisoning of active sites, but was attributed to increasing carbon deposition or to decreasing reactivity of the deposited carbon. Carbon deposited on CaO, especially from residues having large CCR, was less reactive than carbon on the potassium catalyst. The mobility of catalytically active species in deposited carbon layers is a possible explanation for the superior catalytic activity of potassium to CaO. © 1985, The Japan Petroleum Institute. All rights reserved.

Steam reforming of atmospheric, vacuum and solvent-deasphalting residues was investigated using a fluidized bed reactor, where alumina-supported potassium and calcium oxide catalysts were packed. Atmospheric residues were gasified with high efficiency on GaO above 850°C. The catalytic activity, however, decreased markedly with increasing Conradson carbon residue (CGR) of the feed residues. On the other hand, high activity of potassium catalyst was attained even in the gasification of very heavy residues from solvent deasphalting. The decrease in catalytic activity of CaO was not due to sulfur-poisoning of active sites, but was attributed to increasing carbon deposition or to decreasing reactivity of the deposited carbon. Carbon deposited on CaO, especially from residues having large CCR, was less reactive than carbon on the potassium catalyst. The mobility of catalytically active species in deposited carbon layers is a possible explanation for the superior catalytic activity of potassium to CaO. © 1985, The Japan Petroleum Institute. All rights reserved.

We investigated hydrogen production by the steam-iron reaction using iron oxide modified with very small amounts of palladium and/or zirconia at a temperature of 723 K and under atmospheric pressure. Reduction of iron oxide with hydrogen and oxidation of partially reduced iron oxide with steam (Fe3O4 + 4H(2) <-> 3Fe + 4H(2)O) were repeated in the range of reduction degree of 30-50 mol%. Changes in the weight of the samples were monitored using a tapered element oscillating microbalance (TEOM) to control the degree of reduction. Unmodified iron oxide caused significant deactivation due to sintering with increasing number of redox cycles. The addition of a very small amount (0.23 mol%) of palladium or zirconia onto the surface of the iron oxide enhanced the reduction and/or oxidation of the partially reduced iron oxide, which suppressed sintering. Palladium accelerated both the reduction and oxidation rates of partially reduced iron oxide, while zirconia increased only the oxidation rate. Addition of both palladium and zirconia together to the iron oxide resulted in marked enhancement of both reduction and oxidation. (c) 2005 Elsevier B.V. All rights reserved.

The pervaporation tests for n-hexane, 2-methylpentane (2-MP), and 2,3- dimethylbutane (2,3-DMB) were performed using an MFI-type zeolitic membrane at 303 K. In the unary systems, those fluxes followed the order n-hexane >> monobranched hexane (2-MP), > dibranched hexane (2,3-DMB). The ideal selectivities of n-hexane/2-MP and n-hexane/2,3-DMB were 37 and 50, respectively, n-Hexane preferentially permeated in the measurements of a binary mixture of n-hexane/2-MP and n-hexane/2,3-DMB. The feed composition dependence in separating n-hexane/2,3-DMB binary mixtures was studied. The separation factor for the 50/50 n-hexane/2,3-DMB mixture exceeded 120, which was much greater than 54 in the 50/50 n-hexane/2-MP system. When the feed concentration of n-hexane was 10 mol %, the separation factor α(n- hexane/2,3-DMB) at the steady state was as high as 270. n-Hexane effectively inhibited the permeation of 2,3-DMB, even when the concentration of n-hexane was very small.

Permeation rates of L-methionine and acethyl-DL-methionine were measured through ion exchange membranes into sodium chloride solution, assuming that the former was produced from the latter using a immobilized enzyme reactor. Both were permeated through an anion exchange membrane. L-methionine was selectively recovered from a L-methionine and acethyl-DL-methionine mixture by Donnan dialysis using a cation exchange membrane under the various pH conditions, however its rate was smaller than that through anion exchange membrane.<BR>At low pH, the permeation of hydrogen ion was dominant while that of L-methionine was suppressed. The flux of L-methionine attained to a maximum at pH 2 and decreased with increasing pH. Its mechanism was discussed based on ion exchange equilibrium at the interface and mass transfer in the boundary layer and membrane.

Silicon nitride particles with a diameter of 520 &mu;m were coated with ultrafine, submicron silicon powder. The product is expected to show extreme properties in a reactive sintering process.<BR>A uniform and dilute suspension of core particles of silicon nitride in monosilane diluted with argon were introduced into a CVD reactor from a bed of core particles. Additional argon gas was also introduced into the reactor, from the annulus at the bottom of the reactor. The flow resistance of the procuct layer was found to be proportional to the amount of silicon fines. From the results of SEM and TEM, it was found that the core particles were uniformly coated with ultrafine silicon powder with primary particle diameter of around 0.01 &mu;m. In the XRD chart, a weak pattern of silicon fines was found to overlap the pattern of silicon nitride. Without the use of additional gas, on the other hand, core particles coated with a thick deposit were manufactured and a broad XRD chart without the silicon pattern was observed. Heterogeneous deposition of silicon on core particles was found to be avoided by the use of additional gas. The additional gas seemed to be heated in the bottom of the reactor and to mix with reactant gas, thereby causing the homogeneous reaction and suppressing heterogenous CVD by reducing the residence time in the reactor.

We investigated synergetic effects of hybridization of electric field (or plasma) and catalyst. We found that catalytic reactions in plasma proceeded very effectively at ambient temperature, and catalytic reactions in an electric field promoted steam reforming of methane at very low temperature like as 423K.

炭化水素の水蒸気改質にはNi/Al203系触媒が用いられているが、この触媒の問題点は炭素析出による活性劣化である。本研究では,PtおよびPdといった貴金属を活性成分として用い、活性と安定性の向上を目的として触媒の担体にペロブスカイト型酸化物を適用して触媒特性を検討した。また、過渡応答法を用いて反応機構について、格子酸素の役割について検討を行った。担体にはLaAl03, La0.8Sr0.2Al02.9を用いた。比較用に&#61537;-Al203,を用いた。活性金属のPd, Ptは含浸法にて1wt%になるよう担持した。活性試験は固定床常圧流通式反応器で、1073Kにて反応を行った。過渡応答測定では供給ガスの切り替え直後の生成ガス濃度の推移を追跡、解析した。
Pd/α-Al203、Pt/α-Al203両触媒を用いて固定流通式反応器によって定常条件下での反応を行ったところ、Pd触媒、Pt触媒ともにα-Al203では劣化が起きた。これは炭素析出または活性成分である貴金属のシンタリングによる活性劣化と考えられる。一方LaAl03を担体とした場合には、α-Al203担体を用いた場合と比較して、著しく活性と安定性が向上した。特に、Ptはα-Al203担体ではほとんど活性を示さないのに対して、LaAl03を担体とするとPdよりも高い活性を示した。
種々の過渡応答測定の結果により、Pt/LaAl03ではLangmuir-Hinshelwood機構に加え、酸素が格子酸素として担体中に取りこまれてから消費されるMars-van Krevelen機構も同時に起こっていることが示唆された。L-H機構とMVR機構のCO, CO2生成に対する寄与の割合は、L-H機構約40%、MVR機構約60%となり、担体中の格子酸素の反応への寄与が大きいことがわかった。

本研究では、ゼオライトの一種であるモルデナイトを薄膜化し、ゼオライト骨格のイオン交換サイトに固定されたNaカチオンと水分子と相互作用による、高温下での水の選択的分離を目指した。
配位空間場として用いるゼオライト薄膜を合成するにあたっては、種結晶を用いた緻密な薄膜の調製法の開発を中心に行った。まず、平板型の非多孔質支持体上に塗布した種結晶からの結晶成長の様子を観察して,水熱条件下における結晶成長条件の検討を行った。最適化された結晶成長条件を以って,多孔質支持体アルミナ支持体上に塗布した種結晶を成長させることで,支持体表面付近の空隙をゼオライト結晶で埋めることにより,緻密なゼオライト薄膜の調製を合理的に展開することを試みた。
上記の手法により、モルデナイトの薄膜化に成功し、当初のもくろみ通り、250℃までの高温において水選択性を示した。こうした高温における水膜選択性分離の実現は、世界的に初めての例となった。しかしいっぼう、この膜は水素を全く透過させず、極めて特異な選択性をもつことがわかった。また、当初の予定以外にもZSM-5型のゼオライトの薄膜化も試みたところ、高温水選択性のある分離膜を合成することができた。モルデナイト膜と異なり、ZSM-5膜は、水が存在しないと水素、あるいはメタノールが透過したため、透過選択性の発現機構が、モルデナイト膜とZSM-5膜では異なることが示唆された。以上、本研究において、当初の予定を上回る成果が得られたと評価している。いっぼう、水透過選択性の発現機構については、上記のように極めて「不思議」な結果が得られており、アルカリイオン交換型ゼオライト内への高温における各種分子の吸着、拡散挙動の特異性について、今後大きく発展が期待できる研究テーマを見いだすことができたのはないかと考えている。

A disk-type Sm_<0.4>Ba_<0.6>Co_<0.2>Fe_<0.8>O_<3-δ> perovskite-type mixed-conducting membrane was applied to a membrane reactor for the partial oxidation of methane to syngas (CO + H_2). The reaction was carried out using Rh (1 wt%)/MgO catalyst by feeding CH_4 diluted with Ar.
While CH_4 conversion increased and CO selectivity slightly decreased with increasing temperature, a high level of CH_4 conversion (90%) and a high selectivity to CO (98%) were observed at 1173 K. The oxygen flux was increased under the conditions for the catalytic partial oxidation of CH_4 compared with that measured when Ar was fed to the permeation side. We investigated the reaction pathways in the membrane reactor using different membrane reactor configurations and different kinds of gas. In the membrane reactor without the catalyst, the oxygen flux was not improved even when CH_4 was fed to the permeation side, whereas the oxygen flux was enhanced when CO or H_2 was fed. It is implied that the oxidation of CO and H_2 with the surface oxygen on the permeation side improves the oxygen flux through the membrane, and that CO_2 and H_2O react with CH_4 by reforming reactions to form syngas.

Pd/ZSM-5 catalyst shows characteristic features on NO-CH_4-selective reduction reaction, for example, high stability under excess O_2 and steam condition, high activity, and so on. So this catalyst seems to be a good candidate for lean burn combustion of natural gas at high temperature. So far, this catalyst has one defect, which is hydrothermal stability. One of the solutions is exploring new additive like Co. We conducted several attempt for the improvement of this catalyst, and one of the goal is Fe addition for solving these problems.
First, we prepared Pd/ZSM-5, PdFe/ZSM-5, Fe/ZSM-5 catalysts. Experiments were conducted under atmospheric pressure and using fixed bed reactor.
As for the activity and stability of Pd/ZSM-5 and PdFe/ZSM-5 catalysts, PdFe/ZSM-5 showed high NO conversion as high as 55.2%, and it was rather higher than that of Pd/ZSM-5, 42.2%. And there were no difference on the stability of catalyst between these two catalysts. We supposed that there are two different active sites on this Pd/Fe/ZSM-5 catalyst, because Fe catalyst did not show any activities on NO-CH_4-selective catalytic reduction.
So, we postulated that Fe/ZSM-5 catalyst is only effective under the existence of activated carbon species like activated hydrocarbon formed on Pd site

Column flotation is one of the promising processes for the low-cost next generation coal cleaning technologies. As for the column flotation system, many efforts have focused on optimization of apparatus and/or improvement of flotation results so far. However there have been few studies that tried to estimate the relation of flotation results and characteristics properties of coal. We employed a continuous column flotation system for the simple coal cleaning process. Samples used in this study were Adaro, Wallarah, Ermelo, Datong, Taiheiyo, and they were crushed and sieved under 150μm. Then we investigated the demineralization in the column flotation system to estimate the flotation behavior by measuring the contents of inorganic elements in the cleaned coal and the tail refuse. Furthermore we investigated the change in the distribution of coal minerals and their average particle size during the flotation. Each steady state was 5〜14 min after starting the experiment.
As a result, Wallarah was suitable for continuous column flotation. On the other hand, the flotation result of each brown coal (Pasir, Adaro, Berau) was different tendency. We found that column floatation process was a good way to recover carbonaceous materials from low rank coal. This process is very simple so it is suitable for application in Asian countries.

Zeolites have been synthesized by the hydrothermal synthetic method Recently, the dry gel conversion method as the technique of zeolite crystallization was developed. In this report, we investigated the crystallization mechanism of various type of zeolites synthesized by the conventional hydrothermal synthetic method and novel dry gel conversion method. We focus particularly on the aluminosilicate species in not only the atomic scale level, but also in a nano-scale level.
In the case of the hydrothermal synthesis of MFI-type zeolite, when the solubility of aluminosilicate species was low, it was obvious that MFI-type zeolite consisted of aggregate of nano-particles in a diameter of several dozen nanometers. Moreover, it was possible that silicateli-1 was formed by the solid-solid transformation directly from amorphous nano-particles to fine MFI-type crystals.
In the case of the synthesis of EMT-type zeolite by using the dry gel conversion method, we found out that nano-particles fuse and the surface of the dry gel is rearranged, resulting in a distinct hexagonal shape for the EMT crystals.
Additionally, since we suggested that alinninosilicate species having die framework structure of ZSM-5 zeolite exist in the filtrate of alkaline dissolution of ZSM-5, we succeeded the mesoporous materials having a strong acidity caused by the structure of zeolite framework was synthesized by using the aluminosilicate species in the filtrate of alkaline dissolution of ZSM-5.
In conclusion, we investigated the crystallization mechanism of zeolites, focusing on the structural species in a nano-scale level, and the novel acidic catalyst was prepared by using the species having the framework structure of zeolite in a nano-scale.

最近のこの分野における研究動向を調査した.
固体酸性質に関して,(1)ゼオライトとメソポーラス物質内の強い固体酸点の発現,(2)メソポーラス物質内の固体酸点の発現,(3)アルカリ処理によるメソ細孔の発生と触媒活性,およびゼオライト種からのメソポーラス物質の合成,(4)固体酸ゼオライトのノンハロゲン化プロセスヘの応用,(5)ミクロおよびマクロ細孔の触媒反応活性におよぽす影響,の以上5件を調査研究した.
新物質の合成に関して,(1)酸性条件におけるメソポーラス物質の合成,(2)あたらしいメソポーラス物質の合成,(3)最近のゼオライト合成における進歩,(4)電子顕微鏡による構造決定,(5)リン酸ジルコニア層状化合物め化学,の以上5件を調査研究した.
有機化学反応への応用に関して,(1)ナノ空間化学の新展開,Asの除去,不整有機反応など,(2)モンモリロナイトとMS4Aの共用による有機反応,(3)金属ナノ細線の生成と触媒活性,(4)メソポーラス物質による重合触媒MAOの精製,の以上4件を調査研究した.
光触媒反応への応用に関して,(1)Taメソポーラス物質の合成と水の光分解,(2)メソポーラス物質塩基サイトの精製とプロペン分解触媒反応,(3)Crメソポーラス物質の光触媒活性,の以上3件を調査研究した.
さらに,ミクロおよびメソポーラス物質における計算機化学の進歩も調査した.
これらを総合して,今後のこの分野の研究遂行における指針とした.なお,まとめた冊子を印刷し,全国の研究者に配布した.

ゼオライト構造を有したメソポーラス物質は,ゼオライトの強い酸性質と規則的なメソ孔をあわせもつことから,これまでにない新規触媒材料として期待されている.本研究では,ゼオライトのアルカリ溶解から生成したユニットを原料としたメソ多孔体の合成を,流通式反応器を用いて検討した。特に2段式の流通合成反応器を用い,高いpHでアルカリ溶解を行った後に,引き続き低いpHでメソ多孔体を連続的に合成することを試みた。ZSM-5ゼオライトを充填し80℃に保ったカラムに,NaOH水溶液を流通させて,ゼオライトのアルカリ溶解を行った。続いて,ゼオライトのアルカリ溶解液と界面活性剤が混合するように流路を設け,界面活性剤水溶液をテフロンチューブ内を室温で流通させながら,ゼオライトから溶解したアルミノシリケート種を凝集させた。流路の出口から得られた懸濁液に,塩酸を適宜加えてpH調整をした。得られた生成物は550℃で焼成後でも,壊れることなくメソ孔構造が残っており,この試料の窒素吸着等温線では,メソ孔構造の存在を示すと考えられる相対圧0.4付近で緩やかな立ち上がりを示した。またクメンのクラッキングを行ったところ,回分法で合成したM41Sよりもさらに高いクラッキング活性をもつことがわかった。このようにゼオライトのアルカリ溶解過程とメソ多孔体合成過程を分けることは,強い酸性質をもつメソ多孔体の合成に重要であることが示唆された。

In this study, oxygen permeability was improved by three methods (1)Preparation of asymmetric membranes, (2)Optimization of preparation methods, and (3)Investigation of new materials. (1)We investigated the preparation of SrFeCo_<0.5>O_x(SFC2) asymmetric membranes on porous α-alumina substrates. Though gas-tight membranes were obtained by repeating the preparation, these membranes did not show high oxygen flux due to solid-state reaction between membrane materials and substrates or due to differences of compositions from SFC2. To prevent such problems, we established a new preparation method. The dense layer was prepared with SFC2 powder, and the porous support layer was prepared using SFC2 powder mixed with ethyl cellulose. The SFC2 powder and the mixture were simultaneously pressed and calcined. The minimum thickness of the dense layer prepared by this method was 0.1 mm. The asymmetric membranes gave greater oxygen flux than the symmetric membrane. And the oxygen fluxes through these membranes increased with decreasing the thickness of dense layer. (2)SFC2 membranes were synthesized with powders prepared by three different methods, (a)a solid-state reaction method, (b)an evaporation-to-dryness method, and (c)a combined citrate and EDTA. Complexing method. Oxygen fluxes increased in the order of (a)<(b)<(c). Influence of preparation conditions on oxygen flux was investigated. The oxygen flux could be improved by repeated calcination and grinding of parent powder or by sintered at a higher temperature. (3)La in La_<0.4>Ba_<0.6>Fe_<0.8>Co_<0.2>O_<3-δ> was substituted by another rare earth element such as Pr, Nd, Sm. The higher oxygen flux than La_<0.4>Ba_<0.6>Fe_<0.8>Co_<0.2>O_<3-δ> membrane, however, was not obtained. Now we evaluating membranes prepared in this study by applying to a membrane reactor.

MFI-type zeolitic membranes were prepared by a vapor-phase transport (VPT) method on porous alpha-alumina flat disks. Single-and mixed-gas permeation measurements of butane isomers were performed in the temperature range of 300-375 K.The separation factor was always greater than the ideal selectivity. This result is explained by the preferential adsorption of n-butane on MFI in the binary system.
The pervaporation tests for xylene isomers were performed at 303 K.p-Xylene was the most permeable component in the unary system. In the permeation measurements of a binary mixture of p-xylene/m-xylene and a ternary mixture of p-xylene/m-xylene/o-xylene, p-xylene predominantly permeated in the early stage, and then, the Aux of p-xylene decreased gradually and finally became lower than that of the other xylene isomers. The adsorption of m-xylene in the pores of MFI seemed to block the permeation of p-xylene.

ゼオライトの合成には通常Structure Directing Agent(SDA)として有機アミン分子の共存が必要である場合が多く,これら有機アミンのゼオライト結晶化に果たす役割を明らかにすることはゼオライトの結晶化のメカニズムを明らかにする上で重要となる。本研究では我々の開発したドライゲルコンバージョン(DGC)法によりゼオライト合成を行い,生成物に与えるSDAの効果の検討およびドライゲルの相変態途中における生成物のキャラクタリゼーションをおこなった。
分子内のアルキル鎖長を変化させた有機アミンをSDAとして用いた場合,結晶構造の異なるゼオライトが合成された。SDAは,アルキル鎖長が得られるゼオライトの細孔径やintersectionの大きさを限定するものではなく,生成するゼオライトの構造を決定づける役割を果たしている。特にBEAにおいて,テトラエチルアンモニウム(TEA)カチオンがゼオライト骨格と相互作用し結合種を形成していること等を見出した。これらのことは,TEAがBEAゼオライト結晶化過程において重要な役割を担っていることを意味している。
ドライゲルからBEAへの相変態過程を追跡した。結晶化時間の異なるサンプルをSEMにて観察した結果,XRDでは回折線が得られなかったサンプルにおいても,BEAの前駆体と思われる微粒子の生成が見られた。回折線が現れる前にも分子・原子レベルでのBEA前駆体の生成は進行していると推察される。これらの^<29>Si-NMRおよび^<13>C-NMRの結果から,ドライゲル内の親水基であるSi-O-Hが徐々に脱水縮合して疎水基であるSi-O-Siが形成され,TEA周りから徐々にゼオライト骨格が形成されて相変態されてゆくことがわかった。要するに,ドライゲルからBEAゼオライトへの相変態は分子・原子レベルでは経時的に徐々に進行するものの,XRDで観察されるような長周期的規則構造の発達はある程度結晶化が進行した後に急速に起きるものと結論した。

ゼオライト膜の合成条件を確立し、透過、分離、反応試験に境するアイテムを揃えることを目標とした。合成方法は、乾燥ゲルを有機結晶化剤蒸気や水蒸気中で結晶化させる方法(ドライゲルコンバージョン法)を用いた。検討したゼオライトは、SiO_2/Al_2O_3=50とローシリカなMFI型ゼオライトであり、平均細孔径0.1μmの多孔質アルミナ平板上に製膜した。原料ゲルの調製条件、ゲルの製膜条件、結晶化条件などを詳細に検討し、緻密な膜の調製条件を検討した。特に、緻密な膜の合成条件はアルカリ濃度であった。Na_2O/SiO_2=0.19〜1.14、H_2O/SiO_2=40〜120の範囲で結晶化を検討した。Na_2O/SiO_2=0.32-0.41、H_2O/SiO_2=80にて緻密なMFI膜が得られた。l,3,5-トリイソプロピルベンゼン-(TIPB)の透過流束は測定限界(1×10^<-10>mol m^<-2>s^<-1>Pa^<-1>)以下であった。TIPBはMFI型ゼオライトの細孔より大きく、TIPBの透過は膜が緻密でないことを表している。断面SEM観察より、膜の緻密な部分はアルミナ支持体とゼオライトのコンポジット層であり、コンポジット層の厚みが膜の緻密さに影響を与えていることが示された。また、単成分ガス透過試験では、二酸化炭素の透過速度が窒素やメタンより大きかったため、Knudsen拡散以外の透過機構の寄与があることが示された。原料ゲルのSiO_2/Al_2O_3=50とローシリカなMFI型ゼオライト膜の開発に成功し、TWBの透過試験より緻密な膜であることを示した。

Systematic investigation has been done to synthesize non-oxidative functional materials by using flame CVD (Chemical Vapor Deposition) from 1975 to 1997. Formation of ultrafine GeO2 particles in a laminar diffusion flame of Oxygen-hydrogen was experimentally investigated first, and compared with that of SiO2. Tetraethylorthogermanium (TEOG) was used as Ge source. At the lower part of the flame with lean oxygen, the homogeneous uncleation of GeO ultrafine particles occurred. For low feed concentration, they completely sublimated during their ascending through higher temperature zone, and GeO2 ultrafine particles newly nucleated in the upper, oxygen rich, flame region. Most of Geo particles reached to the upper flame region for high feed concentration, and oxidized to Geo2 together with the inhomogeneous uncleation of GeO2. For the case of SiO2 formation, no sublimating phenomena were observed. Solid formation mechanism in a flame is strongly affected by feed concentration, temperature distribution and material itself.
Next, SiN ultrafine particles were synthesized in the same flame by introducing 1,1,1,3,3,3-hexamethyldisilasane (HMDS). SiN particles were sampled only when a sampling tube was inserted just above the reductive inner flame. It can be said that non-oxidative material can be synthesized by flame if we could apart them from oxygen rich, high temperature region of a flame.
It is necessary to utilize premixed flame to realize high producibility. First, we checked and confirmed the possibility of diamond film formation by using oxygen-acetylene premixed flame. Then, SiC thin film was synthesized by introducing HMDS in the flame.
At the final period of the term, we investigated the possibility of propane gas as a fuel. Once we obtained SiC whisker, however, we could not resynthesize the same material at present. The possibility of propane gas as a fuel source is still under investigation.

アルミナ支持体上に塗布したゲルを結晶化させる気相輸送法により、クラックのない緻密なゼオライト膜が得られることは既に報告したが,今年度は緻密なゼオライト膜の生成機構について詳細な検討を行い,以下のような知見を得た。
1.フェリエライト膜合成過程をFESEM観察することによりアルミナ支持体の細孔内にフェリエライト結晶の超微粒子がぎっしりつまっているのがわかった。すなわちアルミナ支持体の細孔はフェリエライト多結晶により埋めつくされているものと思われる。
2.フェリエライト膜合成過程の膜断面におけるSi原子およびAl原子の分布の経時変化をEDX分析により観察した結果,Siがアルミナ支持体上のゲルからアルミナ支持体内へ移動し,Al原子はアルミナ支持体から支持体の上方へ移動していることがわかった。
3.支持体上のゲルの結晶化過程のSEM観察から,ゲルはダイナミックに移動しながら結晶化していることがわかった。
4.支持体上にフェリエライト結晶を置いて同様し操作を行うと,結晶は支持体内へ,その配向性を維持しながら沈み込んでいくように見えた。
5.ゲルを泌みこませた支持体上のゲルを取り去ってから同様の結晶化操作を行うと支持体上へゼオライト結晶が生えてくるのが観察された。
以上のことから,緻密なゼオライト膜は固相のダイナミックな結晶化,融解,再結晶化過程によりアルミナゼオライト複合相が形成される結果として出来ると結論した。

山元で行える安価で簡便なコールクリーニングプロセスとしてカラム浮選方に注目し、カラム浮選成績と石炭の表面物性評価法であるフィルム浮選成績との相関関係を検討している。フィルム浮選成績に応じたカラム浮選プロセスの装置設計や操作指針が与えられれば、炭種に応じたカラム浮選プロセスの構築が可能となる。
前年度までに瀝青炭である大同炭、エンシャム炭およびイリノイ炭についてフィルム浮選成績とカラム浮選成績との比較を行い、疎水性強化剤であるケロシンの添加効果が炭種により大きく異り、フィルム浮選成績だけでカラム浮選成績を予測し得ないことを見出した。
今年度は無煙炭であるホンゲイ炭および山西炭について同様の実験的検討を行ったところ、炭種によりケロシン添加効果が大きく異るものの、フィルム浮選成績とカラム浮選成績は良好な一致をみた。これは無煙炭においては炭素質と鉱物質との単体分離性が良いこと、および無煙炭の炭素質は芳香族炭素を多く含んでいることによると思われるが、詳しい機構については今後の課題と考えている。

我々が新規に開発した固体ゲル転換法によるゼオライト合成法を用いて、ゼオライト薄膜の合成を行った。本年度は第1に薄膜生成機構を明らかにすることを目的として検討を行った。さらに得られた膜を用いて液混合物および、ガス混合物の透過分離試験を行い、ゼオライト膜の分子レベルにおける分離への適用性を検討した。1)ゼオライト膜合成法の確立 原料の調整条件、ゲルの乾燥温度、乾燥時間などをパラメーターとして、固体ゲル転換法による多孔質アルミナ支持体上へのゼオライトの製膜を行った。XRDおよびFE-SEMにより結晶化過程の詳細な検討を行い、結晶化条件下ではゲルはMobileであり、適当な条件を選択することによりアルミナ多孔質支持体内に浸透、結晶化し、緻密なアルミナーゼオライトコンポジット膜となることを見いだした。2)透過分離試験 得られたFER膜について、ピンホールの生成の有無を1,3,5-トリイソプロピルベンゼン(TIPB)の浸透気化試験により検討したところ、FER膜にはピンホールが無いことがわかった。この膜はベンゼン/パラキシレン混合物の浸透気化分離に対して100-600と極めて高い選択性を発揮した。また、パラキシレン/オルトキシレン混合物に対しても、3とまだ小さいが選択性が発現することがわかった。これは、供給側のゼオライト細孔入口において選択性がためと考察した。また、高温(200℃以上)における分離特性の評価を行うため、ポリイミド樹脂とグラファイト製Oーリングを用いた膜のシール法を開発した。ガス透過能は膜内に吸着した水蒸気量に著しく影響されることを見いだした。

気相輸送法によって緻密なゼオライト膜の得られる条件を探索し、その分離特性を検討した。SiO_2/Al_2O_3=25、所定のpH(=11〜13)のアルミノシリケートゲルを調製した。得られたゲルを、アルミナ支持体の上に製膜し、乾燥した。これを、トリエチルアミン、エチレンジアミン、水の混合蒸気雰囲気下0-4日間、453Kに保った。
ガラス基板上に製膜して363Kで乾燥後、クラックあるいは剥離の有無によりゲルの緻密さを評価した。ゲルの緻密さは溶液のpHに依存した。高pHほど乾燥ゲルの比表面積は小さくなり、ケイ酸ナトリウムを用いた場合pHが11.6以上で、コロイダルシリカを用いた場合12.0以上で、クラックのない薄膜状乾燥ゲル膜が得られた。
上記により決定した最適な条件にて、アルミナ支持体上に製膜し、気相輸送法により結晶化した。ケイ酸ナトリウムからはANAが、コロイダルシリカからはMORが得られた。コロイダルシリカで表面処理すると、ケイ酸ナトリウムからはFER、コロイダルシリカからはMFIが得られた。
ゼオライト膜表面をSEMにより観察したところ、表面のゼオライト粒子層には大きな空隙が存在することがわかった。1日目ですでにアルミナ支持体の細孔の中にもMORが生成しているようにみえる。2日目になるとアルミナ細孔内の結晶数が増え、4日目にはアルミナとMORの界面付近の細孔内は完全に埋まり、約10μm程度の緻密層が形成された。
ベンゼン、p-キシレン0.86:1混合物の浸透気化分離を行った。分離係数は160以上となり、、気液平衡の値11.3を大きく上回った。MOR膜のピンホールの有無を検討する目的で、TIPBの浸透気化分離を行ったが、TIPBは透過しなかったことから、膜内にピンホールは存在しないと結論した。MORの細孔入口で形状選択性が発現したものと考えられる。

内径27mmの小型カラム浮選器および内径80mm、高さ1850mmの大型カラム浮選器を用いた浮選結果、および石炭粒子の表面疎水性の評価手法であるフィルム浮選法による測定結果を比較検討した。いずれのカラム浮選装置において、特に工夫した気泡発生装置を用いて直径2mmの一定した大きさの気泡を塔底で均一に分散して発生させた。石炭粒子としては75μm以下の、イリノイ炭、エンシャム炭および大同炭を用い、気泡安定化剤としてメチルイソブチルカルビノール、石炭の疎水性強化剤としてケロシンを用いた。
小型カラム浮選器による実験結果によると精炭回収率、脱灰率の序列は共に大同炭>エンシャム炭>イリノイ炭であり、脱パイライト率はエンシャム炭>大同炭>イリノイ炭であった。フィルム浮選結果から、石炭粒子の疎水性の強さは大同炭>エンシャム炭>イリノイ炭であり、これは精炭回収率および脱灰率の序列と一致した。
大型カラム浮選装置による実験では、空塔速度0.66,1.99x10-2ms-1および塔高1.25、1.85、2.15mについて検討した。塔頂から精炭を所定の時間に一定時間採取後、その重量、灰分を測定し、炭素質、灰の浮選速度の経時変化を求めた。ガス空塔速度が小さい場合、精炭中の灰の含有率の経時変化は小さいが、高空塔速度の場合、時間の経過に従い精炭中の灰の含有率は増加した。ガス空塔速度が大きいと、気泡下部のウェークと共に上昇した固形分が、そのままフロス層に取り込まれるものと考えられる。

ゼオライト薄膜を用いた分子レベルでの高度連続分離プロセスの実現を目指し、緻密な薄膜状各種ゼオライト膜の合成法を確立することを目的とした。本研究では無機多孔質支持体上に緻密に製膜した乾燥ゲルを我々が開発した気相輸送法により結晶化し,ゼオライト薄膜を合成した。無機多孔質支持体としては平均孔径0.1μmのアルミナ多孔質板を用いた。
特に、モルデナイト(MOR)、フェリエライト(FER)膜についてその分離透過特性を検討した。XRDより両者とも多結晶膜であった。両膜を用いて、1,3,5-トリイソプロピルベンゼン(TIPB)の透過試験を室温で行った。TIPBはいずれの膜も透過しなかった。TIPBはMOR,FERの細孔より大きい分子であり、したがって、MOR膜、FER膜にはTIPBの透過できるような結晶粒界の空隙は存在しないと結論できる。以上より、ピンホールのない緻密なゼオライト膜の合成に成功したと結論した。
浸透気化法により芳香族炭化水素の分離特性を室温で検討した。FER,MOR膜ともベンゼン/パラキシレン混合物からベンゼンが選択的に透過することがわかった。分離係数は気液平衡より予測される値(10.1)より著しく大きく、MOR膜では160程度、FER膜では100程度の値が得られた。FER,MORの細孔内ではパラキシレン、ベンゼン分子のすれ違いは起きにくいと考えられるので、上記の高い選択性は細孔入口において形状選択性が発現した結果と結論した。
以上、気相輸送法によるピンホールのない緻密なゼオライト膜の合成に、世界で始めて成功した。これらの膜は、ゼオライトの特徴である形状選択性を発揮することを実験的に確認した。

ゼオライト薄膜を用いた分子レベルでの高度連続分離プロセスの実現を目指し、緻密な薄膜状各種ゼオライト膜の合成法を確立することを目的とした。本研究では無機多孔質支持体上に緻密に製膜した乾燥ゲルを我々が開発した気相輸送法により結晶化し、ゼオライト薄膜を合成した。無機多孔質支持体としては平均孔径0.1μmのアルミナ多孔質板を用いた。
緻密な膜の生成条件は多くの因子が関係するが、最も重要なポイントは(1)ゲル調製時のpH、および(2)支持体とゲルの濡れであることを見いだした。特にゲル調整時のpHはシリカ源にもよるがpH=11.6-12.0の範囲で厳密に調製する必要があることがわかった。MORおよびANA膜では支持体のアルミナが一部溶出し、ゼオライト骨格内に取り込まれたものと考えられた。一方、支持体を予め表面処理によって安定化すると、アルミナの溶出を抑制しハイシリカのMFI,FER膜を合成することができた。以上のように原料試薬、ゲル組成、支持体の前処理法等を変え、MFI,FER,MOR,ANA各膜の最適な合成条件を決定した。
ガス透過試験装置を試作した。得られた膜を用いて室温から373Kの範囲においてヘリウム、メタン、窒素、酸素、水素、二酸化炭素などの無機ガスのガス透過特性を評価した。各ガスの透過流束の温度依存性はクヌッセン拡散から外れ、活性化拡散を示した。こうしたガス透過実験の結果からピンホールのほとんど存在しない緻密な膜が得られたものと考えられた。
以上、ゼオライト膜の合成に当たっての基礎的な検討を終え、緻密な膜を得るために必要な因子を抽出することができた。ガス透過実験からゼオライト薄膜を用いた分子レベルの超精密分離プロセスの実現の可能性を指摘することができた。

For the development of novel particle processing such as particle coating, utilization of fluidizing phenomena of particles under plasmatic conditions is available. Coating of SiC on the surface of particles from SiH_4 and CH_4 was studied using a D.C.plasma jetting fluidized bed reactor, consisting of fluidized bed superimposed on a D.C.plasma generator. SiH_4 and CH_4 were introduced through the ports forming vortex flow around the plasma jet. Two types of gas injection methods, premix and diffusion-mix methods, were compared. The diffusion-mix method gave high conversions of SiH_4 and CH_4, compared with the premix method. Though fine beta-SiC powder was trapped in the filter installed on the way of exit line, deposition of SiC on the bed particles was not confirmed by X-ray diffraction, probably due to the coating of amorphous or very thin SiC.The elemental analysis along the cross section of the coated particles showed that most silicon was deposited inside the particles and not near the surface. It can be speculated that the reaction gases excited in plasma were diffused into the particles and deposition occurred inside the particles.
Fundamental characteristics of a microwave plasma-fluidized bed reactor for particle processing were also investigated. Alumina or polycrystalline silicon was used as a bed material. Fluidizing phenomena and stability of plasma state seem to depend on the kinds of plasma gas and the level of dielectric loss of particles. Optical observation showed that plasma was generated within bubbles in the bed. Methane conversion was carried out as a model reaction. Although the level of methane conversion in the presence of particles was lower than that in the absence of particles, methane was effectively converted to carbon in the microwave plasma-fluidized bed.

その特異な細孔構造により分子レベルでの選択性を有するゼオライトを高度分離膜として製膜する手法の開発を目的として、ゼオライトの新しい合成法の開発を行った。すなわち従来法の水熱合成ではゼオライトの多結晶粉末が合成されるので製膜は困難と考え、一旦成型した乾燥シリカアルミノゲルを有機蒸気に気相中で接触せしめゼオライト化する手法の開発を行った。合成実験には試作のオートクレーブを用いた。
結晶化温度は253Kとし、生成物の構造に及ぼすシリカアルミノゲルのpH、ナトリウムイオン濃度、有機テンプレートの種類の影響を主として検討した。トリエチルアミンとジエチルアミン共存下、pH=7-11の広い範囲でフェリエライトが得られることを見いだした。結晶化には両有機テンプレートの共存が必須であった。ナトリウム濃度を下げるとZSM-5が得られた。1-プロパノールを用いてもZSM-5を合成することができた。pH>11ではアナルサイムとなった。また、条件によってはKZ-1,KZ-2が得られることを見いだした。
固体高分解能NMRスペクトルよりゲル中のアルミニウムはすべて結晶格子中に取り込まれており、またアナルサイムを除いてシリコンも良好に結晶化していることがわかった。従って、本方法を用いると仕込どおりのシリカアルミナ比を有するゼオライトが合成できると考えられる。
本年度の研究結果より、我々が提案する方法で良好に結晶化した各種ゼオライトが合成できることが明かとなり、ゼオライト薄膜を無機支持体上などへの製膜の可能性が示された。次年度以降は多孔質ガラス、多孔質アルミナ膜などを支持体として製膜実験を行いたいと考えている。

ジェッテイング流動層石炭ガス化炉は、ガス化助剤(酸素または空気)をノズルからジェット状で局所的に高温に達せしめ、装置全体のガス化効率を高めるとともに、灰の凝集を器壁から離れた場所で行なうことを特徴とする。このようなガス化炉ではガス送入部(グリッド部)の構造が層全体のガス化性能に大きく影響するため、グリッド部におけるガスと粒子の挙動や化学反応の局所的な進行を解析することが肝要である。そこで、小型バッチ式流動層を用いて局所的温度分布とガス濃度分布を実測し反応の進行を検討するとともに、グリッド部内のガスおよび粒子の挙動モデル解析するための基礎的検討を行なった。
太平洋炭の乾留チャ-のガス化において、生成ガス組成およびグリッド部近傍における反応の進行に対するノズルから送入した酸素とコ-ン型分散板から送入した水蒸気の寄与を、それぞれ単独に送入した結果と比較することにより検討した。1173Kではジェット周辺部に(アニュラス部)で生成した水素の一部はノズルから送入された酸素により酸化され再び水蒸気となること、水性ガス化反応あるいはシフト反応により二酸化炭素は生成するが発生炉ガス化反応により消費されるため二酸化炭素の層内での濃度変化は比較的小さいことが明らかとなった。また、層温度の影響を1073ー1273Kで検討した結果、層温度が低いときにはジェット近傍では完全酸化反応が主として起こるが、層温度が高くなるにつれ部分酸化が支配的に起こるようになり、アニュラス部の下部における水性ガス化反応が速やかに進行することが確められた。
さらに、コ-ルドモデル実験により得られたガスおよび粒子の挙動に関する知見をもとに、グリッドゾ-ンモデルを構築した。流動層のアニュラス部におけるガス混合速度は、固定層のそれと比較してかなり大きいと推測した。

本研究の目的はノズルからジェット状で送入し局所的に高温に達せしめ、装置全体のガス化効率を高めるとともに、凝集灰を生じさせるタイプの流動層ガス化炉を想定したうえで,装置全体のガス化反応の進行を把握するため酸素(空気)吹き込み口近傍の局所的現象を実験的に解明し,反応・熱効率上昇に必要な因子の抽出と制御法を確立することにある。本年度は種々の形状のガス送入口を用いて,層内の温度分布、生成ガス組成およびそれらの経時変化を測定し,生成ガス組成に及ぼすガス吹き込み法の影響を検討した。さらに、層内の局所的な反応の進行を解析するための基礎的検討を行なった。
内径43mmの小型流動層に石炭チャ-を充填し、バッチ式反応器内におけるガス生成量,酸素送入部における局所的温度分布およびその時間的変化を測定した。平板型のガス送入口形状を用いた場合と比べ、コ-ン型分散板から水蒸気を送入し,分散板中央に設けたノズルより酸素を送入した場合には一酸化炭素に富む良好な組成が得られることがわかった。
定常状態における炉内の局所的ガス化剤,生成ガス濃度を実測するため、石炭をアルミナで、ガス化剤を不活性ガスで希釈し,トレ-サ-としてヘリウムを炉内に送入することにより,ガス化剤,生成ガスの移動現象を解析した。その結果ジェット-アニュラス間のガス交換の様子が明らかとなった。ジェット、アニュラスにおけるガス濃度の違いは顕著であり、層内の局所的な反応の進行の解析が可能であることが示された。またアニュラス部における層高方向のガス化反応の進行も明らかであった。特にノズルより送入された酸素は主にジェット-アニュラスの境界付近にて石炭し,一酸化炭素を生成することが明らかとなった。

膜分離は省エネルギー技術であり、新規な分離膜、および分離膜と反応器を組み合わせた反応分離場の創生は、エネルギー・環境問題の解決に寄与することが期待できる。本研究では、分子と同程度のミクロ細孔をもつ無機材料であるゼオライトを薄膜化することによって、分子レベルの分離が可能で耐熱性、耐酸性に富む新しい分離膜を開発し、さらにゼオライト膜と固体触媒反応器を用いた新規な反応分離を実現することを目的とした。 モルデナイト膜、ZSM-5膜の二種のゼオライト膜について、その生成過程を検討し、結晶の育成条件と生成する構造の相関を明らかにし、膜の緻密化を合理的に進めるための指針を得た。また、得られた緻密なゼオライト薄膜について、高温（150-300℃）、高圧下（0.-3.0 MPa）における水-メタノール-水素のガス透過試験を実施し、ゼオライト薄膜の分離特性の検討を行った。その結果、モルデナイト膜は水素，メタノールの透過を阻止し，水が選択的に透過した。いっぽう， ZSM-5は水存在下で水，メタノールが透過し，水素の透過を阻止した。このような高温でも機能を発揮する分離膜はこれまで例がなく、本研究による大きな成果である。また、とくに、モルデナイト膜の水選択性の発現機構を検討するために、Na交換型モルデナイト結晶を用いて水蒸気、メタノールの吸着実験を行った。その結果、本実験のような高温下では、ゼオライトのアルミノシリケート骨格ではなく、交換カチオンであるNaと極性分子である水の強い相互作用によって水の吸着が起こり、水が細孔内に選択的に吸着するものと考えられた。しかし、いっぽうでメタノールもモルデナイト細孔に若干吸着することがわかった。モルデナイト膜によって、水素のみならずメタノールの透過も阻止される理由については、吸着特性のみでは完全には説明できず、ゼオライト膜の構造に踏みこんだ議論を進める必要があると推察した。

　ETS-4は結晶性チタノシリケートであり，結晶構造に由来する均一で剛直なミクロ孔を有する。また，Ti原子はETS-4骨格中で4配位と6配位の2種類の配位構造を形成するが，4配位Tiサイトは陽イオン交換サイトとなりうる。ここにNa+，K+，Sr+などのアルカリ金属イオンが交換することで，ETS-4のミクロ孔径を狭めることができ，チッ素・酸素を分子ふるい作用により，分離することが可能となる。本研究では，このような特長をもつETS-4を多孔質支持体上に薄膜化し，チッ素・酸素を膜分離する手法を開発することが目的である。その中で本年度は，粉末のETS-4の調製条件の検討を行った。　ETS-4はSi源としてケイ酸ナトリウム，Ti源として塩化チタンまたはTiアルコキシドを用いる。ただし，用いるTiの種類により，結晶化後に得られる生成物が変わることが知られている。Ti源としてTiブトキシド・モノマーを用いて，SiO2: TiO2: Na2O: H2O: H2O2=1.0: 0.10: 0.65: 67.5: 0.60の組成で原料混合物を調製し，190℃，静置条件下で48時間結晶化を行ったところ，生成物はETS-4であった。ここで原料にH2O2を加えるのは，Tiブトキシドの加水分解を緩やかに進めるためであり，このようにして得られた水酸化チタンモノマーがシリカ源と重合し，結果，ETS-4への結晶化が進行したと考えられる。いっぽう，Ti源に塩化チタンを用いて，SiO2: TiO2: Na2O: H2O: HCl=1.0: 0.30: 1.25: 9.88: 0.32の組成で原料混合物を調製し，190℃で24時間結晶化を行った場合には，結晶性の低いdenseなチタノシリケート相とquartzが生成した。塩酸を用いて塩化チタンを激しく加水分解した場合には，チタネートとシリケートとの重合があまり起こらなかったために，ETS-4が得られなかったと考えられる。　これまでにTi源の加水分解速度を制御することで，再現よくETS-4が得られることが明らかなった。今後はこの手法を用いて，ETS-4を多孔質支持体上への薄膜化を行い，また，得られた薄膜のチッ素・酸素分離試験を行い，高い分離性能を示すETS-4薄膜の開発を進めていく。

1．緒言　ゼオライト膜の研究開発はこれまで，多くのtry　and errorによる実験の積み重ねによって合成条件を最適化し，透過分離特性の最適化を図ることが行われてきた。BNRIにおいてはA型ゼオライト膜の脱水膜としての工業化が急がれているが，ゼオライトには多くの種類の骨格構造が存在し，また化学組成（主にはシリカアルミナ比）も変化に富むことから，ゼオライトの膜材料としてのポテンシャルについては，いまだに研究開発の端緒についたばかりといえよう。 ゼオライト膜の透過分離性能を支配するのは，膜厚，結晶の配向，緻密さ，粒界の大きさといった膜構造，および分子ふるい作用，吸着特性といったゼオライト固有の物理化学的特性である。しかしいっぽうで，これら構造，物理化学的特性と分離透過特性の関係，両者の制御方法についてはほとんど明らかになっていないと言ってよい。 したがって，本研究の大きな目的は，合成条件と生成する構造の相関，膜構造と透過分離性能の相関を明らかにし，透過分離性能の合理的な制御方法を明らかにすることにある。本年度は，ZSM-5，モルデナイトを用いた薄膜に関して，高温高圧下における新規な透過分離性能を見出したので報告する．2．実験 母体の種結晶を粉砕して得たスラリーを用いて種結晶を多孔質アルミナ支持体上に担持し，これを水熱合成法により成長させることにより緻密で透過分離性能の高い膜を合成する手法を確立した。水、メタノール，水素の3成分系混合ガスから，水素を供給（高圧）側に残し，水および/あるいはメタノールを選択的に透過せしめることを目的に透過実験を行った．本年度は，モルデナイト膜については全圧30気圧までの高圧下における透過分離性能を評価した．いっぽう，ZSM-5膜に関しては全圧は1気圧に固定して透過実験を行った．３．結果・考察3.1．　合成実験結果　多孔質アルミナ上にZSM-5あるいはモルデナイトの種結晶を塗布し，合成溶液組成および結晶化条件をそろえて結晶化を行ったところ，ZSM-5種結晶を塗布した支持体上にはZSM-5膜が，モルデナイト種結晶を塗布した支持体上にはモルデナイト膜が生成することを見出した．すなわち，種結晶の種類によって異なる構造のゼオライトを製膜することが可能となった．3.2．　モルデナイト膜の透過分離性能　30気圧、250℃までの範囲で透過実験を行った。水素の透過量は膜のシール部分からのリーク程度であり，水選択性を発現したことがわかった。モルデナイト膜は高温高圧系において高い水選択性を発揮する膜であると結論できる。選択性は条件にもよるが，水素に対する水の選択性は10000を超えた．水素／メタノール混合ガス，水／メタノール混合ガスの透過試験結果より，水以外の水素，メタノールは膜をほとんど透過しないものと考えられた。　水蒸気濃度20％，常圧，150－250℃において，Na型モルデナイト結晶粉末を用いて，水，メタノールの吸着実験を行った。その結果，水の吸着はモルデナイトの高温安定性に寄与することがわかった。いっぽう，メタノールは吸着するものの透過が起きないことが明らかとなった．このことは，水選択性がミクロ細孔内への吸着性の違いにより発現したことを否定しており，今のところ，モルデナイト結晶の積層欠陥によって細孔が著しく狭まり，結果としてメタノールが透過できなかったものと推察している．3.3．　ZSM-5膜の透過分離性能　モルデナイト膜を用いた場合の結果とは異なり，メタノール／水素混合系では，両者とも透過し，ほとんど分離しなかった．これに対し，水／水素系では水が選択的に透過し水素の透過が阻止された．また，水／メタノール／水素3成分系では，水とメタノールが膜を透過し，水素の透過が著しく阻止された．こうした，水の共存による選択性の発現は，水の細孔内への強い吸着によるpore-fillingが原因と考えられるが，詳細は今後検討する予定である．

1. 緒言細孔径0.74 nm、Si / Al = 1.5~3.0で親水性をもつY型ゼオライトを膜とすることで、水 / 有機物からの脱水や有機混合物分離への適用が期待されている。透過分離性能の高い膜を調製するためには膜構造を制御することが重要になる。しかし、Y型ゼオライト膜構造の制御について報告した例は少ない。そこで、本研究では、Y型ゼオライト層の形成過程、および種々の調製条件が膜構造に及ぼす影響を確認することを目的とした。膜構造に影響する因子には、支持体上の種結晶、ゲル組成、エージング条件、結晶化条件などがある。そこで種々の結晶化条件が膜構造に及ぼす影響を検討した。また、多孔質支持体上では、ゼオライト層の形成過程を観察することは困難であるため、無多孔平板上における種結晶を用いたY型ゼオライト層の形成過程を検討した。2. 実験方法NaYを粉砕し、蒸留水を加えて調製したスラリーに、アルミナ支持体を3 min浸漬した後、ディップコート法によって支持体上に種結晶を塗布した。種結晶を塗布した支持体および塗布していない支持体上に静置あるいはかく拌条件下で結晶化した。結晶化後の支持体は、蒸留水によって流水洗浄、もしくは流水洗浄した後浸漬洗浄した。膜の透過分離性能は10wt%水 / エタノールを用いたPV試験によって評価した。スピンコート法によりアルミナ平板上に種結晶を塗布した後、かく拌条件下、373 Kで結晶化(1~13 h)した。結晶化後の平板は流水、浸漬洗浄した。結晶化後の平板上でのY型ゼオライト層の形成過程をFE-SEMにより観察した。3. 結果・考察3-1. 製膜条件の検討種結晶を塗布してない支持体を用いて結晶化したところ、Y型ゼオライト層は形成しなかった。このことから、Y型ゼオライト膜の調製においては、種結晶を塗布することによりゲル層中で核発生し、Y型ゼオライト層が形成すると考えられる。静置あるいはかく拌条件下いずれで結晶化した場合にも、長時間結晶化すると膜中のFAUの結晶化度が減少し、GISが生成し始めた。膜におけるFAUの結晶化度の減少は、結晶の溶出および熱力学的に安定なGISへの相転移によるものだと考えられる。結晶化した後、流水洗浄した膜のPV試験を行った結果、結晶化後蒸留水に浸漬すると、フラックスが大幅に向上することを見いだした。結晶化後の膜はアモルファスで覆われており、浸漬洗浄することでアモルファスが溶出したと考えられる。3-2. 平板上でのY型ゼオライト層の形成種結晶を用いたY型ゼオライト層の形成においては、ゲル層中での核発生と結晶成長が同時に進行していることが示唆された。そしてさらに結晶化時間を長くすると、Y型ゼオライトが溶出し、GISが生成していくことを確認した。

乾燥状態のゲルを有機結晶化剤蒸気雰囲気下で結晶化させる方法（ドライゲルコンバージョン法）により、SiO2/Al2O3比＝1000のMFI型ゼオライトの平均細孔径0.1μmの多孔質アルミナ平板への製膜を試みた。ゲル調製から熟成、支持体へのゲルのコーティング、結晶化に至るまで、多くの合成条件が生成物の物性に影響するため、それぞれの最適化を試みた。特に緻密な膜の合成に重要な条件は原料中のアルカリ濃度であった。アルカリ濃度Na2O/SiO2比＝0.13-0.23の範囲で緻密な膜が得られた。アルカリ濃度が充分でない場合には、原料ゲルの加水分解が充分に起こらず、また高すぎる場合には加水分解が優先して起きるため、ゼオライト骨格の形成が起きないことがわかった。ベンゼン／ｎ-ヘキサンの浸透気化分離試験を行なった。ピンホールがわずかでも存在すると全く選択性を示さなかったが、ピンホールフリーの膜では等モル混合物で５程度の分離係数を示した。無機ガス（ヘリウム、窒素、二酸化炭素、メタン）透過試験では、ピンホール濃度が減少するほど、無機ガス透過流束は大きな正の温度依存性を示した。また、各ガスの透過流束の差も大きくなる傾向にあった。以上の結果は、分離機能の発現にはピンポールの制御、すなわちゼオライト結晶粒界の制御が本質的に重要であることを示している。　ゼオライト膜を工業的に用いるにはモジュール化が必須であり、それにはチューブ状支持体への製膜法の開発が必要である。そこで、上記で確立した合成条件を用いて、外径７㎜のチューブ状アルミナ多孔質支持体への製膜を試みた。チューブ表面への均一な製膜には、ゲルを支持体細孔中へ吸引・製膜することが必要であった。また、乾燥途中でゲルが重力あるいは毛管凝縮によって片寄らないよう、工夫した。こうして得られた膜を用いて、窒素／二酸化炭素混合物の透過試験を行なったところ、表面拡散の効果による選択性の発現を認めた。研究成果の発表投稿予定Synthesis of MFI Zeolite Membrane and Its Separation Properties. Microporous and Mesoporous Materials, Elsevier.