1. Synthesis of hierarchical SAPO-34 to improve the catalytic performance of bifunctional catalysts for syngas-to-olefins reactions
- Author
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Suhan Liu, Guoquan Zhang, Ye Wang, Kang Cheng, Wang Ziwei, Xiaojian Min, Qinghong Zhang, Lei Zhang, Mengheng Wang, Jincan Kang, and Runtian Gao
- Subjects
010405 organic chemistry ,Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Bifunctional catalyst ,chemistry.chemical_compound ,Chemical engineering ,Methanol ,Physical and Theoretical Chemistry ,Selectivity ,Zeolite ,Bifunctional ,Brønsted–Lowry acid–base theory ,Syngas - Abstract
Bifunctional process integrating methanol synthesis and methanol-to-olefins conversion provides a new synthetic strategy for lower olefins (C 2 C4=), whereas designing matchable zeolite components is still challenging due to the harsh reaction conditions. Here, a hierarchical SAPO-34 zeolite with a sandglass-like hollow structure is synthesized from an aluminum-rich precursor gel, which provides an abundance of crystal defects during zeolite crystallization. The bifunctional catalyst obtained by integrating the hierarchical SAPO-34 and ZnO ZrO2 oxide offers a C2 C4= selectivity of 80% at 25% CO conversion with excellent stability in syngas conversion. We demonstrate that in the presence of high-pressure hydrogen, a moderate density of acid sites is the prerequisite for obtaining high C2 C4= selectivity in syngas/methanol conversion, because the olefins are easily hydrogenated into alkanes by excessive Bronsted acid sites. The hierarchical architecture significantly prolongs the lifetime of bifunctional catalysts, by facilitating C2 C4= desorption and slowing down the coking rate.
- Published
- 2021