engleski

The Role of Preparation Way of Zeolite Beta Crystals on Their Acid Places Content

Since the intracrystalline diffusion of the reactants and products within zeolite catalyst (microporous crystals of micrometer size) is slow, the limitations of their efficiency should be avoided adding mesoporous voids (channels, holes). Introduction of mesoporous voids (hierarchical structure of the crystals) can be obtained using additional mesoporous template (e.g. CTAB) during catalyst synthesis, or by postsynthesis treatment of classically synthesized microcrystals (dealumination and desilication using e.g. NH4F or NaOH solutions). Another important issue in catalysis efficiency (we study methanol-to- olefine conversion – MTO) is number of active places (i.e. Lewis and Brönsteadt acid places). Its number can be increased with number of hetero T-atoms within framework. Beside direct synthesis of catalyst (zeolite Beta) of larger Al content, postsynthesis treatment (wet impregnation) can be used. After treatment, results show significant increase of number of both types of acid sites.

mesoporous beta ; wet impregnation ; zeolite ; postsynthesis treatment ; acid sites

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