engleski

The role of preparation way of zeolite ZSM-5 crystals on their acid places

One of the most important factors in zeolite catalyst for methanol-to-olefine conversion (MTO) is the number and accessability of “acid places”. The number of the acid places (Brönstedt or Lewis) largely depends on the way of the catalyst preparation. Generaly, catalyst with more Al content within the framework, have more acid places. On the other hand, their accessability towards MTO reaction can be limited to the thin subsurface layer within crystals, due to the difficulties of the intracrystalline diffusion of the reactants and products. In this paper we have prepared hierarchical ZSM-5 crystals using several methods for synthesis: classical hydrothermal synthesis followed by etching (TPAOH/NaOH), synthesis with microporous (TPAOH) and mesoporous template (CTAB), postsynthesis treatment by wet impregnation, in order to increase the number of heteroatoms (Al, Sn) in the zeolites framework. Results shows substantial increase in the number of acid places after wet impregnation process.

Zeolite ; ZSM-5 ; wet impregnation ; acid sites

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