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

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 MCM-48/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 deg C is 8h.