Strategy towards enhanced performance of zeolite catalysts: Raising effective diffusion coefficient versus reducing diffusion length

Abstract

In the present study, two strategies for improving the catalyst efficiency either by (1) raising the effective diffusion coefficient or (2) reducing the diffusion length of zeolite catalysts are presented. These two strategies are exemplified by the preparation of (i) ordered mesoporous material with zeotype secondary building units and (ii) self-assembled nanosized zeolites. The textural properties, acidity, and the results from the cumene cracking show that the strength and amount of Brønsted acid sites of the mesoporous materials are inferior, due to their amorphous pore walls. Even though the lifespan of ordered mesoporous material with zeotype secondary building units during cumene cracking can be improved due to the effective diffusion coefficient enhancement, the strength and amount of Brønsted acid sites related to the reaction are not akin to conventional microporous zeolites. While the self-assembled nanosized zeolites with short diffusion length shows enhanced catalytic performance by diffusion controlled reactions.