Preparation of catalytic membranes with controlled structure and its application to membrane reaction

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Catalytic membrane reactors were investigated using two types of catalytic membranes : MFI membranes which had separation ability and catalytic activity in the top layer and silica membranes which had separation ability in the top layer and catalytic activity in the supporting layer.MFI zeolite membranes having different Si/Al ratios were prepared by secondary growth of crystalline colloidal seeds under hydrothermal conditions. An MFI membrane of Si/Al=∞ showed a n-C_4H_<10> permeance of 1.5x10^<-5> m^3(STP)m^<-2>s^<-1>kPa^<-1> and a n/i-C_4H_<10> selectivity of 15 at 150℃. By addition of Al into MFI membranes, the zeolite layers appear to be randomly-oriented and n/i-C_4H_<10> selectivities were decreased. Methylation of toluene using MFI catalytic membrane reactors was carried out from 400-500 ℃. Toluene conversions increased with reaction temperature and p-xylene selectivity achieved was 80 % at maximal, suggesting the effectiveness of MFI catalytic membrane reactors.Methane steam r … More eforming with and without added oxygen was theoretically and experimentally investigated using microporous silica membranes, which allow the permeation of hydrogen as well as other gases in reactants and products. A simulation of catalytic membrane reactors was carried out for a co-current, isothermal, and plug-flow-type membrane reactor with the selective permeation of hydrogen through microporous membranes. Catalytic membrane reactors, consisting of a silica microporous layer and a Ni-catalyst layer, were prepared. Catalytic membrane reactors showing a hydrogen selectivity over nitrogen of 30-100 with hydrogen permeances of 0.5-3x10^<-7> mol m^<-2>s^<-1>Pa^<-1> were applied to the steam reforming of methane with and without the addition of oxygen. The reaction was carried out at 500 ℃, and the feed and permeate pressure were maintained at 100 and 20 kPa, respectively. Methane conversion, X_<CH4>, increased up to approximately 0.8 beyond the equilibrium conversion of 0.44 by extracting hydrogen in permeate stream. Less