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

采用水热条件下胶体晶种二次生长法制备了具有不同Si/Al比的MFI沸石膜，研究了MFI沸石膜和SiO2沸石膜在催化膜反应器中的催化性能。Si/Al=∞的MFI膜在150℃时的正-<10>C_4H_2渗透率为1.5 × 10 ~<-5>（-3）m ~（-3）s <-2>~（-3）<-1>kPa ~<-1>（-3），正/异-<10>C_4H_2选择性为15。在MFI膜中加入Al，使分子筛层出现无规取向，正/异构C4 H4<10>选择性降低。在400-500 ℃温度范围内，采用MFI催化膜反应器进行甲苯甲基化反应。甲苯转化率随反应温度的升高而升高，对二甲苯选择性最高可达80%，表明MFI催化膜反应器的有效性。 ...更多信息 使用允许反应物和产物中的氢以及其它气体渗透的微孔二氧化硅膜，在理论上和实验上研究了有和没有加入氧的重整。对微孔膜选择性渗透氢气的并流、等温、推流式膜反应器进行了催化膜反应器的模拟。制备了由二氧化硅微孔层和镍催化剂层组成的催化膜反应器。催化膜反应器显示氢对氮的选择性为30-100，氢渗透率为0.5- 3 × 10 - <-7>4 mol·m-3·<-2>s-1·<-1>Pa-3，<-1>用于甲烷的水蒸气重整，有和没有添加氧气。反应在500 ° C下进行，并且进料和渗透物压力分别保持在100和20 kPa。甲烷转化率，X_<CH4>，通过提取渗透物流中的氢而增加到超过0.44的平衡转化率高达约0.8。少

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