Hierarchical Shell-Like ZSM-5 with Tunable Porosity Synthesized by using a Dissolution-Recrystallization Approach

Abstract

Zeolites have been widely used in various fields in industry, such as catalysis, separation, and adsorption, etc. The small pore size of the micropores in the zeolite could lead to severe diffusion resistance in mass transfer. Numerous efforts have been dedicated to imposing hierarchical pore systems into zeolites by using templates or leaching methods. Here, we report the synthesis of single-crystalline hierarchical shell-like ZSM-5 by utilizing a dissolution-recrystallization post-treatment on mesoporous ZSM-5. Tetrapropylammonium hydroxide solution was used in the post-treatment. The hierarchical porosity in the crystalline shell can be controlled by adding sodium cations into the synthesis system. The hierarchical shell-like ZSM-5 reported here shows higher catalytic activity in acetalization reactions containing bulky molecules.

Keywords: dissolution-recrystallization; hierarchical porosity; mesoporous materials; microporous materials; zeolites.