A seed surface crystallization approach for rapid synthesis of submicron ZSM-5 zeolite with controllable crystal size and morphology

A method based on seed surface crystallization (SSC) mechanism has been proposed for facile, rapid, controllable and low-cost synthesis of ZSM-5 zeolite with submicron-size and interesting core-shell structure. The crystallization process of the ZSM-5 zeolite with all sizes can be accomplished within 2.5 h. The morphology and size of zeolite ZSM-5 products can both be facilely adjustable in the domain of 270-1100 nm depending upon the characters of silicalite-1 seeds, while the thickness of aluminum-containing zeolite ZSM-5 shells can be well tuned by changing the amount of silicalite-1 seed. More interestingly, the siliceous silicalite-1 seeds within the obtained zeolite crystals could be selectively removed by alkaline treatment. By systematically tracking the crystallization process combined with mathematical analysis, the crystallization of ZSM-5 zeolites in the reaction system is revealed as SSC mechanism with a size-independent, linear growth process. Their crystal growth rate is calculated as c.a. 0.15 mu m h(-1) regardless of the seed size and amount. Crown Copyright (C) 2009 Published by Elsevier Inc. All rights reserved.