Synthesis of hierarchical ZSM-5 zeolite in a rotating packed bed: Mechanism, property and application

Abstract

Hierarchical (micro/mesopore) ZSM-5 zeolites were hydrothermally synthesized in a rotating packed bed (RPB) which substantially enhances micromixing for the high viscosity reaction system. Herein, the effects of four operating processes with different micromixing intensity on nucleation/crystal growth process as well as physicochemical properties of ZSM-5 zeolites were investigated. Results indicate that enhancing micromixing by RPB in the zeolite synthesis could facilitate the formation of Al sites and shorten the nucleation and crystallization period. ZSM-5 samples prepared by RPB exhibit hierarchical structure, smaller average particle size, more uniform particle size distributions, larger specific surface areas, higher catalytic stability as well as more acid sites than those obtained by (stirring tank reactor) STR. While adopting the ZSM-5 samples prepared by RPB for catalyzing C4-olefin cracking reaction, the conversion of C4-olefin and yield of propylene are higher than those obtained by STR.