Hierarchical zeolites with enhanced textural and catalytic properties synthesized from organofunctionalized seeds

A novel strategy for the synthesis of hierarchical zeolites with enhanced surface area, porosity, and catalytic activity which is based on perturbing the growth of zeolite crystals by silanization of the zeolite seeds to hinder their further aggregation, was investigated. The method has been successfully applied to the synthesis of both ZSM-5 and beta zeolites using phenylaminopropyl- trimethoxysilane (PHAPTMS) as the silylating agent. The effective incorporation of the organosilanes into the zeolites occurs with properties close to that of the synthesis gel and no change was observed in the content of silylating agent before and after the hydrothermal treatment. The effect of drastic changes induced in the zeolite properties by seed silanization treatment on their catalytic behavior has been evaluated using the cracking of polypropylene (PP) as a test reaction. The results show the significant effect of the presence of high external surface area and secondary porosity in the zeolites.