MCM-56分子筛催化苯与丙烯液相烷基化反应性能

Catalytic Performance of MCM-56 Molecular Sieve for Benzene Alkylation with Propylene

在晶化釜内动态水热合成了MCM-56分子筛,采用过氧化氢回流处理方法脱除模板剂,获得了高比表面积分子筛MCM-56[MCM-56(H2O2)].采用XRD,N2气吸附-脱附,NH3-TPD和FTIR等对其结构和酸性进行表征,考察了HMCM-56(H2O2)分子筛在苯与丙烯液相烷基化合成异丙苯中的催化性能.研究结果表明,过氧化氢回流处理能够有效去除模板剂.与焙烧去除模板剂的HMCM-56(C)相比,HMCM-56(H2O2)分子筛的BET比表面积达到563m2/g,外表面积提高近2倍.酸性表征说明,与HMCM-56(C)相比,HMCM-56(H2O2)的总酸量较高而酸强度分布不变.在苯与丙烯液相烷基化反应中,HMCM-56(H2O2)分子筛表现出更好的低温活性和更高的异丙苯选择性.

MCM-56 zeolite was prepared by hydrothermally dynamic method. The as-made MCM-56 was detemplated by treating with a 30% H2O2 solution to obtain MCM-56 （H2O2） zeolite instead of being treated with high-temperature calcination. The structure and acid properties of samples were studied by means of XRD, N2 adsorption-desorption, NH3-TPD and FTIR. The BET surface area of MCM-56（H2O2） can be improved significantly by hydrogen peroxide detemplation. A higher external surface area of 301 cm^2/g was obtained for HMCM-56（H2O2） compared with 134 cm^2/g for HMCM-56（C）. The amount of acid sites has been increased by hydrogen peroxide treatment, while the acid strength has not been modified. Both the HMCM-56 zeolite detemplated by H2O2 and by calcination were used in benzene alkylation with propylene in liquid phase. Under our operation condition, HMCM-56 （H2O2） shows a relative high activity and selectivity to cumene than HMCM-56 （C） , especially under a relative low reaction temperature and benzene-to-propylene molar ratio.