Nature of the Active Sites of VOx/Al2O3 Catalysts for Propane Dehydrogenation

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• 作者：Gang Liu ; Zhi-Jian Zhao ; Tengfang Wu ; Liang Zeng ; Jinlong Gong
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：August 5, 2016
• 年：2016
• 卷：6
• 期：8
• 页码：5207-5214
• 全文大小：474K
• 年卷期：0
• ISSN：2155-5435

文摘

Supported VO_x catalysts are promising for use in propane dehydrogenation (PDH) because of the relatively superior activity and stable performance upon regeneration. However, the nature of the active sites and reaction mechanism during PDH over VO_x-based catalysts remains elusive. We examined active species by attaining various fractions of V⁵⁺, V⁴⁺, and V³⁺ ions by adjusting the surface vanadium density on an alumina support. The results reveal a close relationship between TOF and the fraction of V³⁺ ion, indicating that V³⁺ was more active for PDH. In situ diffuse reflectance infrared Fourier transform spectroscopy showed the same strong adsorbed species during both propane dehydrogenation and propylene hydrogenation. The results indicated that such an intermediate may correspond to V species containing a C═C bond, i.e., V–C₃H₅, and a reaction mechanism was proposed accordingly.