Direct, single-step synthesis of hierarchical zeolites without secondary templating

Abstract

Hierarchical ZSM-5 was directly synthesized by controlling the nucleation, growth and template-free self-assembly of zeolite precursors formed in the initial stage of the zeolite crystallization process. The facile synthesis results in spherical particles primarily composed of a micro-mesoporous core of aggregated 30–50 nm MFI nanocrystals, and a thin crystalline shell. MFI nanocrystal assembly coupled with a possible dissolution–crystallization mechanism results in a template-free route to broadly distributed mesopores and, thereby, a ca. 25 nm diffusion length in a micrometer-sized particle. The materials exhibit enhanced mass transport and superior catalytic activity for bulky molecules.