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

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.