Methanol to olefins conversion over silicoaluminophosphates with AEI structure: Effect of the active site type


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Abstract

Effect of the type of active site on the catalytic properties of microporous crystalline silicoaluminophosphates with AEI structure synthesized at 150, 170, and 190°C has been investigated. The state of the active site was changed by varying the catalyst synthesis conditions. It has been established that during the synthesis of silicoaluminophosphates with the AEI structure from the reaction mixture of the same composition, an increase in the temperature and crystallization time leads to an increase of the silicon content and crystal size growth. The observed changes in the physicochemical properties are accompanied by the change of the silicon state in the structure of silicoaluminophosphates with the predominant formation of silicon “islands” via the SM3 mechanism. According to 29Si NMR data, the formation of active sites of silicoaluminophosphates via the SM2 mechanism in the form of isolated silicon atoms in the structure is also observed for these materials. The presence of such sites, along with the morphological features of the crystals, determines the unusual catalytic properties of silicoaluminophosphate with AEI structure in MTO process, which are a high ethylene yield up to 41 wt % at an ethylene: propylene molar ratio of 1: 6.

About the authors

V. I. Kasnerik

Faculty of Chemistry

Email: eknyazeva62@mail.ru
Russian Federation, Moscow

S. V. Konnov

Topchiev Institute of Petrochemical Synthesis

Email: eknyazeva62@mail.ru
Russian Federation, Moscow

I. V. Dobryakova

Faculty of Chemistry

Email: eknyazeva62@mail.ru
Russian Federation, Moscow

A. O. Ivanov

Topchiev Institute of Petrochemical Synthesis

Email: eknyazeva62@mail.ru
Russian Federation, Moscow

E. E. Knyazeva

Faculty of Chemistry; Topchiev Institute of Petrochemical Synthesis

Author for correspondence.
Email: eknyazeva62@mail.ru
Russian Federation, Moscow; Moscow

I. I. Ivanova

Faculty of Chemistry; Topchiev Institute of Petrochemical Synthesis

Email: eknyazeva62@mail.ru
Russian Federation, Moscow; Moscow

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