Sub-micron sized hierarchical porous ZSM-5 particles with controllable mesoporous structures by changing the alkalinity in the synthesis using NaOH

Abstract

This work reports that sub-micron sized hierarchical porous ZSM-5 particles with controllable mesoporous structures can be facilely synthesized in a seed-assisted system without using any secondary templates or organic additives. The results showed that typical samples so-obtained display relative uniform ellipsoidal sub-micron sized particles consisting of loosely packed primary nanocrystals. The mesoporous structures of ZSM-5 zeolite particles can be effectively introduced and adjusted by solely changing the quantity of NaOH in the initial synthesis mixture. The NaOH dosages significantly affect not only hierarchical mesoporosity but also the ratio of Si/Al and thus acidity of the final ZSM-5 product. Moreover, the effect of synthesis hydrothermal procedure was also investigated. The typical sample Z5-0.12 possesses high crystallinity, BET surface area, well-developed mesoporosity and improved catalytic performance in LDPE cracking. This approach constitutes a facile and cost-effective pathway to prepare sub-micron sized hierarchical porous ZSM-5 particles and might promote their application in industry.