两步晶化法制备MCM-48/ZSM-5复合分子筛

Synthesis of MCM-48/ZSM-5 Composite Molecular Sieve by Two-step Crystallization

利用两步晶化法制备了高水热稳定性的MCM-48/ZSM-5介微孔复合分子筛.通过SEM、TEM、XRD、IR和N2吸附脱附进行表征,结果显示,该材料的结构不同于简单的机械混合,而是具有微孔孔壁和三维立方介孔孔道的复合材料,其孔道尺寸为2.6nm左右.该复合分子筛在沸水中处理6h后,介孔结构仍保留完好.通过考察晶化时间对复合分子筛的影响,证明了介孔和微孔的组装是一个竞争的过程,复合分子筛中介孔与微孔结构的比例随晶化时间的变化而变化,且具有介孔孔道和微孔孔壁的复合分子筛150℃的最优晶化时间为8h.

Composite micro/mesoporous MCM-48/ZSM-5 materials were successfully prepared by using a two-step synthesis route. The different structures of composite materials compared with the mechanical mixture were characterized by powder XRD,IR spectroscope, SEM,TEM, N2 adsorption and the influence of the crystallization time was investigated. The results show that the composite MCM-48/ZSM-5 materials possess mesoporous wall constructed by secondary building units characteristic of ZSM-5 and three-dimensional pore structure with pore size of about 2.6nm. The mesoporous framework of MCM48/ZSM-5 is still found to be somewhat preserved after treatment in boiling water for 6h. It is proved that the self-assemble is a competitive process and the ratio of mesopore to micropore has a close relationship with crystallization time. The optimum crystallization time under 150℃ is 8h.