Synthesis of hierarchical ZSM-5 nano-aggregated microspheres for application in enhancing the stability of n-hexane aromatization

Abstract

Incorporating mesopores into ZSM-5 zeolite to form a hierarchical structure has been regarded as an important approach to enhance the diffusivity and catalyst lifetime for light alkane aromatization. Herein, hierarchical ZSM-5 nano-aggregated microspheres were simply and directly synthesized and characterized using TPAOH as a single template without any mesoporous templates or zeolite seeds. The size of the ZSM-5 microspheres and the distribution of mesopores could be regulated by controlling the alkalinity of the synthesis gel. A possible self-assembly mechanism was proposed based on tracing the formation process of ZSM-5 microspheres with crystallization time. The ZSM-5 microspheres modified with Zn were applied in n-hexane aromatization and exhibited better catalytic stability than conventional mono-dispensed microporous ZSM-5 due to the existence of accessible mesopores.