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Experimental studies on the design of shell- and tube-type heteropolyacid (HPA)-polymer composite catalytic membrane reactors (CMR) and their applications to the vapor-phase decomposition of methyl tert-butyl ether (MTBE) were reported. H3PW12O40 (PW) was used as a catalyst for the reaction, and polyphenylene oxide (PPO) was used as a membrane material. It was found that the single-phase (PW-PPO/Al2O3, type-1) and the composite (PW-PPO/PPO/Al2O3, type-2) catalytic membranes not only showed catalytic reactivity for the reaction, but also were perm-selective for methanol with respect to isobutene and MTBE. The selective removal of methanol through the catalytic membrane inhibited the unfavorable reverse reaction (MTBE synthesis), and at the same time accelerated the MTBE decomposition reaction. The PW-PPO/PPO/Al2O3 CMR showed a superior performance compared to the PW-PPO/Al2O3 CMR. The enhanced performance of PW-PPO/PPO/Al2O3 CMR was attributed to the intrinsic perm-selective capabilities of the PW-PPO catalytic membrane and the sub-layered PPO membrane. The PW-PPO/PPO/Al2O3 catalytic membrane with high PW loading was less perm-selective than that with low level of PW loading. Although the PW-PPO catalytic layer itself had a lower intrinsic activity than the bulk PW catalyst in a normal reactor, PW-PPO/PPO/Al2O3 catalytic membrane could be utilized in a membrane reactor to achieve higher MTBE conversions than equilibrium values by means of chemical equilibrium shift at high cut-off.

The catalytic partial oxidation of CH4 to syngas was carried out over an Ni–Mg/Al mixed-oxide catalyst prepared from layered double hydroxide-type precursors. The catalysts were characterized by XRD, TPR, UV-DRS, XRF, BET and CHNS analysis. The effects of the catalyst composition and the calcination temperature on the catalytic performance and the extent of catalyst deactivation were investigated. Ni–Mg/Al oxide catalysts converted CH4 into syngas efficiently with high selectivity. The catalyst performance was strongly related to the Ni particle size and the calcination temperature. The catalysts that were calcined at higher temperature exhibited a better catalytic performance. In conclusion, the NiAl2O4 spinel phase had a positive effect on the stability of the catalyst.

Experimental studies on the performance of shell and tube-type membrane reactors equipped with heteropolyacid-polymer composite catalytic membranes were carried out for the vapor-phase decomposition of MTBE (methyl tert -butyl ether). Three types of catalytic membranes comprised of 12-tungstophosphoricacid (H 3 PW 12 O 40 , PW) and polyphenylene oxide (PPO) were designed in this work. The PW-PPO/Al 2 O 3 (type-1), PW-PPO/PPO/Al 2 O 3 (type-2) and PW/PPO/Al 2 O 3 (type-3) catalytic membranes not only showed catalytic reactivity for the reaction, but also were perm-selective for the reaction species. The selective removal of methanol through the catalytic membrane led to an equilibrium shift in a direction favorable to MTBE decomposition. Among three types of catalytic membrane reactor, the PW-PPO/PPO/Al 2 O 3 (type-2) catalytic membrane reactor showed the best performance. The enhanced performance of the PW-PPO/PPO/Al 2 O 3 (type-2) catalytic membrane reactor can be attributed to the intrinsic perm-selective capabilities of the PW-PPO catalytic membrane and the sub-layered PPO membrane.

The vapor-phase MTBE decomposition was examined in a shell and tube-type catalytic membrane reactor (CMR). 12-Tungstophosphoric acid (PW) was used as a catalyst and poly-2,6-dimethyl-1,4-phenylene oxide (PPO) was used as a polymer material. A single-phase CMR (PW-PPO/Al2O3, type-1) and a composite CMR (PW-PPO/ PPO/ Al2O3, type-2) were successfully designed and characterized. It was revealed that the single-phase PW-PPO/ Al2O3 showed perm-selectivities for reaction products. The selective removal of methanol through the catalytic membrane shifted the chemical equilibrium toward the favorable direction in the MTBE decomposition. The PWPPO/ PPO/ Al2O3 showed the better performance than PW-PPO/ Al2O3. The enhanced performance of PW-PPO/ PPO/ Al2O3 CMR was due to the intrinsic perm-selectivity of PW-PPO and the additional separation capability of sub-layered PPO membrane.

Simulation and experimental studies on the double pipe (shell and tube) polymer membrane reactors were examined for the vapor-phase methyl tert-butyl ether (MTBE) decomposition. H3PW12O40 catalyst supported on silica was used as an active catalyst for the reaction. Polyphenylene oxide (PPO), polysulfone (PSF) or cellulose acetate (CA) membrane coated on the double-layered alumina tube was used as a constituent membrane. It was observed that permeabilities of methanol through each polymer membrane were higher than those of isobutene and MTBE regardless of the kind of polymer material used. The selective removal of methanol through polymer membrane shifted the chemical equilibrium toward a favorable direction in the model reaction. The MTBE conversions in the membrane reactors were much enhanced compared to the equilibrium conversions. The PPO membrane reactor showed the best performance under the experimental conditions. The simulation results on the performance of the membrane reactors were in good agreement with the experimental results within the error of ±5%. It was revealed from the simulation that the CA membrane reactor showed the best performance at high contact time whereas the PPO membrane reactor showed the best performance at low contact time in terms of MTBE conversion, isobutene yield and isobutene selectivity. It was also observed that the performance of membrane reactor was much improved with the decrease of coating amount of polymer membrane and reaction temperature, but with the increase of partial pressure of MTBE. It was concluded that the simulation program developed in this work described the performance of the membrane reactor very well for the vapor-phase MTBE decomposition.

Simulation and experimental studies on the polymer membrane reactor were examined for the vapor-phase MTBE (methyl tert-butyl ether) decomposition. A double pipe (shell and tube type) membrane reactor comprising 12-tungstophosphoricacid catalyst and polymer membrane was designed. The polymer membrane was coated on the porous alumina tube. Polyphenylene oxide (PPO), polysulfone (PSF) or cellulose acetate (CA) was used as a constituent membrane material. It was observed that permeabilities of methanol through each polymer membrane were higher than those of isobutene and MTBE regardless of the kind of polymer membrane used. The selective permeation of methanol through each polymer membrane shifted the chemical equilibrium toward the favorable direction in the MTBE decomposition reaction. MTBE conversions in the membrane reactors were much enhanced compared to the equilibrium conversions. The MTBE conversions were increased with the increase of reaction temperature and with the decrease of reaction pressure. Simulated results were in good agreement with the experimental results. The PPO membrane reactor showed the best performance in the experimental condition.

H3PMo12O40-polymer composite film catalysts were prepared by blending these two materials using a methanol–chloroform mixture by a membrane preparation technique. Polyphenylene oxide (PPO), polyethersulfone (PES) and polysulfone (PSF) were used as blending polymers. A H3PMo12O40-PPO composite catalyst coated on Al2O3 was also prepared. These catalysts were used as heterogeneous catalysts for the liquid-phase tert-butanol (TBA) synthesis from isobutene and water. It was found that all the composite film catalysts showed higher catalytic activities than homogeneous H3PMo12O40 in the TBA synthesis. Among the composite film catalysts, H3PMo12O40-PPO showed the best catalytic performance. Not only high absorption capability of H3PMo12O40-PPO for isobutene but also stability of H3PMo12O40-PPO in the reaction medium was responsible for such a catalytic performance. The H3PMo12O40-PPO/Al2O3 also showed a higher activity than a homogeneous solution of H3PMo12O40.

H3PMo12O40-polysulfone composite film catalysts were prepared with a membrane preparation technique by blending these two materials using dimethylformamide or methanol–chloroform mixture. They were used as fixed-bed catalysts for the vapor-phase ethanol conversion in a continuous flow reactor. It was observed that H3PMo12O40was finely dispersed throughout a polysulfone matrix. The composite catalysts showed the modified catalysis compared to the bulk acid. The effects of solvent on the pore characteristics and catalytic activities of these composite film catalysts were investigated.

Heteropolyacid-imbedded polymer film catalysts were applied for the vapor-phase catalytic reaction. Thin film catalysts were prepared by membrane technology using homogeneous heteropolyacid-polymer solutions. It was found that heteropolyacid was finely and uniformly dispersed throughout the polymer matrix. Heteropoly-acid catalyst could be designed by this method to enhance acid or oxidation catalysis. Future aspects of the film catalyst were also described in this work.

H3PMo12O40 embedded in a polysulfone film was prepared by blending H3PMo12O40 with polysulfone using dimethylformamide as a common solvent and its catalytic activity for 2-propanol conversion reaction was examined. The prepared film catalyst showed a higher yield for acetone but a lower yield for propylene than H3PMo12O40 itself. The decrease of acidic function of the film catalyst was mainly due to dimethylformamide strongly adsorbed on the acid sites of H3PMo12O40, while the increase of oxidation function was due to uniformly and finely distributed H3PMo12O40 in the film. When the film catalyst was used as a membrane, it showed higher ratio of acetone to propylene than H3PMo12O40 itself.

A heteropoly compound has acidic and redox catalytic properties. It also shows a characteristic sorption behavior depending on the properties of the adsorbates. Most nonpolar substances such as olefins are adsorbed only on the surface (surface area is less than 10 m[sup 2]/g), while polar compounds such as alcohols, water, pyridines, and ethers mostly penetrate into the bulk to form a pseudo-liquid phase. Thus, some reactions occur only on the surface, whereas others occur in the bulk of the heteropoly acid. A heteropoly compound is highly soluble in some organic solvents. Taking advantage of this property, heteropoly acid can be blended with a polymer to form a porous film by using a common solvent which dissolves both the heteropoly compound and the polymer. Since polymer materials are thermally unstable at high temperatures, their utilization has been restricted within the lower temperature ranges. Therefore, if the heteropoly acid and blended polymer film is used as a catalyst, it must be applied in low-temperature reactions. However, if the heteropoly acid catalyst is well dispersed in the bulk of the film, a high catalytic activity can be expected for certain reactions even at low reaction temperatures. In this study H[sub 3]PMo[sub 12]O[sub 40]-blendedmore » polysulfone (abbreviated as PMo-PSF hereafter) film was prepared and its catalytic activity for the ethanol conversion reaction was investigated. 5 refs., 4 figs., 1 tab.« less

The methyl t-butyl ether (MTBE) decomposition reaction was carried out in an inert membrane reactor and in a conventional fixed bed reactor to compare the reactor performance of the two reactors. The inert membrane reactor was composed of 12-tungstophosphoric acid (H 3 PW 12 O 40 ) catalyst and polyphenylene oxide membrane. The maximum attainable conversion of MTBE in the inert membrane reactor was always greater than that in the fixed bed reactor at temperatures ranging from 80 to 110° C. The selective permeation of methanol through the membrane caused chemical equilibrium shift toward the favourable direction. It was also revealed that the adsorption characteristics of MTBE into the bulk of the heteropoly acid catalyst also played an an important role in the increase in MTBE conversion.

Novel palladium hollow spheres were synthesized using silica spheres as a template, and they were successfully applied as recyclable heterogeneous catalysts for Suzuki cross coupling reactions.

H2 and CO permeabilities through H3PMo12O40-blended polyvinylalcohol membrane and catalyst-free polyvinylalcohol membrane were measured. The blended membrane showed better selectivity and higher permeation flux of H2 than the catalyst-free polyvinylalcohol membrane. Its enhanced H2 separation ability was mainly due to the selective sorption property of PMo embedded in the polyvinylalcohol membrane.

Membrane-like H3PMo12O40-polymer composite film catalysts were successfully prepared using homogeneous H3PMo12O40-polymer solutions by a membrane preparation technology, and they were applied as heterogeneous catalysts to the vapor-phase ethanol conversion and MTBE decomposition, and to the liquid-phase t-butyl alcohol (TBA) synthesis. Finely and uniformly dispersed H3PMo12O40 catalysts supported on polymer materials were obtained. The catalytic properties of the composite film catalysts were affected by the nature of solvents and polymer materials used. The composite catalysts showed the enhanced catalytic activities in the model reactions compared to the mother catalyst. The modified catalytic properties of H3PMo12O40-polymer composite film catalysts were confirmed by characterization.

H 3 PMo 12 O 40 -polysulfone composite film catalysts were prepared by membrane preparation techniques. These two materials were blended using dimethylformamide or methanol-chloroform mixture. Pore characteristics of H 3 PMo 12 O 40 -polysulfone composite catalysts were controlled by a phase inversion method. The composite film catalysts were used as fixed-bed catalysts for the vapor-phase ethanol conversion in a continuous flow reactor. Effects of solvent on the pore characteristics and catalytic activities of composite catalysts were investigated. It was observed that H3PMo 12 O 40 was physically dispersed throughout polysulfone matrix as fine particles. Pore characteristics of composite catalysts strongly depended on the preparation conditions. All the composite film catalysts showed the modified catalytic activities in the model reaction compared to the mother acid.

The SCR of NO with propene over Ru-HZSM-5 catalyst was investigated using temperature swing reaction (TSR) technique. In the period of increasing temperature to 598K, the conversion of NO to N2 was transiently increased up to 75% with a duration of one minute. It was recognized that a sudden activation of carbonaceous deposits accumulated on the catalyst played an important role in the remarkable enhancement of the catalytic activity. With the adding of water vapor, the duration of the enhancement was significantly extended. We suggest that the TSR technique using Ru-HZSM-5 catalyst is an advantageous method in the SCR of NO, considering the activity enhancement and the simplicity in operation.

Heteropolyacid-imbedded polymer film catalysts were prepared using homogeneous heteropolyacid-polymer solutions by membrane preparation technology with the variation of solvents and polymer materials. They were characterized by SEM, XRD and DSC. It was found that heteropolyacid was finely and uniformly dispersed throughout the polymer matrix. They were applied to the vapor-phase ethanol conversion and MTBE (methyl tert-butyl ether) decomposition. The film catalysts showed enhanced conversions and product yields in the model reactions. Porosity of the film catalysts was controlled by a phase inversion method. The blending patterns and crystal structures of HPAs were also confirmed to ensure the modified catalysis of HPA-imbedded polymer film catalysts.

Novel palladium hollow spheres were synthesized using silica spheres as a template, and they were successfully applied as recyclable heterogeneous catalysts for Suzuki cross coupling reactions.