Controllable Synthesis of Core-Shell Structured Zsm-22 Via One-Pot Approach

Abstract

ZSM-22 zeolite with core-shell structure was synthesized via a facile one-pot/three-step synthesis route. Epitaxy growth of high silica zeolite shells on Al-rich zeolite nanocrystals was conducted to passivate the acid sites on the external surface. More importantly, it provides excellent tunability and controllability to both the size of products and the thickness of the Si-rich shell by modulating the crystallization conditions in separate steps. The crystallinity, morphology, chemical composition, textural and acidic properties of core-shell ZSM-22 were characterized to reveal the formation mechanism in the crystallization process by various techniques, such as XRD, SEM, ICP, FTIR, Py-IR, N 2 -physisorption, and XPS analysis.

Keywords: ZSM-22, core-shell, one-pot, epitaxy growth