Direct construction of hierarchical ZSM-5 microspheres aided by 3-glycidoxypropyltrimethoxysilane

Abstract

A silane coupling agent of 3-glycidoxypropyltrimethoxysilane (GPTMS) was added to a conventional ZSM-5 synthesis system to construct hierarchical ZSM-5 zeolites. The effects of the GPTMS dosage and the crystallization time on the structure, morphology, porosity and acidity of the synthesized hierarchical ZSM-5 have been investigated by XRD, SEM, TEM, N2 adsorption, and NH3-TPD techniques. The results indicate that the addition of GPTMS drives the formation of microspheres consisting of ZSM-5 crystallites and improves the mesoporosity of ZSM-5 samples, while an excess dosage of GPTMS inhibits the crystallization of ZSM-5. When prolonging the crystallization time, the ZSM-5 crystallites in the microspheres grow larger. The hierarchical ZSM-5 shows greatly improved catalytic performance in the benzylation of benzene with benzyl alcohol after removing the silicic species by alkaline rinsing.