A catalytic process for the synthesis of light olefins from CH3Br over Zn-modified SAPO-34 molecular sieve

Autor: Ying Ying Zhang, Yi-Qiang Deng, Yuefang Li, Lang Chen, Shuang-Feng Yin, Chak-Tong Au
Rok vydání: 2015
Předmět:
Zdroj: Reaction Kinetics, Mechanisms and Catalysis. 115:691-701
ISSN: 1878-5204
1878-5190
DOI: 10.1007/s11144-015-0841-4
Popis: We propose a process for the generation of light olefins (C 2 = + C 3 = ) from CH3Br using SAPO-34 and Zn-modified SAPO-34 (ZnAPSO-34s) molecular sieve as catalysts. Compared to SAPO-34, the as-synthesized ZnAPSO-34 catalysts exhibit enhanced CH3Br conversion and C 2 = + C 3 = selectivity for this catalytic reaction, it is especially so over ZnAPSO-34 with a Zn/Si molar ratio of 0.02 (Zn34-20), giving a C 2 = + C 3 = yield of 73.3 % at a CH3Br conversion of 92 %. Based on the results of powder X-ray diffraction, scanning electron microscopy, and temperature-programmed desorption of ammonia, the relationship between particle size, acidity and catalytic efficiency was investigated. Some smaller particles are generated with Zn incorporation. The crystal size decreases with the rise of Zn content in ZnAPSO-34s. The results indicate that the smaller particles of ZnAPSO-34s with a higher amount of acid sites show enhanced conversion and better stability, whereas a higher amount of weak acid sites causes better C 2 = + C 3 = selectivity. In addition, a proper presence of water in CH3Br improves the selectivity to C 2 = + C 3 = .
Databáze: OpenAIRE
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