Recently, solvent-free synthesis methods of ZSM-5 (aluminosilicate) zeolite materials have been reported in the literature. Solid starting materials are typically ground for a period of time followed by thermal heating to synthesize crystalline ZSM-5 zeolite. These studies generally have focused on products formed after the thermal heating. However, very little is known about the reaction intermediates formed during the mechanochemical pre-reaction grinding step and how the pre-reaction impacts the subsequent synthetic success. In this study, the mechanochemical approach used to synthesize ZSM-5 zeolite was investigated. The effect of grinding time was investigated first to find the minimum necessary grinding time. Controlled experiments were used to monitor chemical and physical changes occur during the grinding step. It was found that extended grinding initiates exchange reactions between hydrated Na2SiO3 and NH4Cl to form NaCl and to liberate ammonia and water which found to be necessary to facilitate and enhance the crystallization rate during subsequent 180 °C autoclave reactions. Both manual (mortar and pestle) and ball mill (FTS 1000) grinding were compared in this study. The synthesized products were characterized using XRD, BET nitrogen adsorption, SEM, and ICP-OES. The findings in this study provide valuable insights to inform the tuning of the synthesis conditions that produce ZSM-5 zeolite materials with high stability and crystallinity.

Mechanochemical reaction pathways to enhance solvent-free synthesis of ZSM-5 zeolite

2019 Spring National Meeting

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