Chinese Journal of Catalysis ›› 2020, Vol. 41 ›› Issue (2): 276-285.DOI: 10.1016/S1872-2067(19)63444-3

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Nature of active phase of VOx catalysts supported on SiBeta for direct dehydrogenation of propane to propylene

Chong Chena,b, Minglei Suna, Zhongpan Hua, Yuping Liub, Shoumin Zhangb, Zhong-Yong Yuana,b   

  1. a National Institute for Advanced Materials, School of Materials Science and Engineering, Nankai University, Tianjin 300350, China;
    b Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071, China
  • Received:2019-05-26 Revised:2019-07-09 Online:2020-02-18 Published:2019-11-04
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21421001, 21573115), the 111 project (B12015), and the Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering (2017-K13).

Abstract: The VOx catalysts supported on dealuminated Beta zeolite (SiBeta) with varying V loadings (from 0.5 to 10 wt%) are prepared and tested for their catalytic activities in the reaction of direct dehydrogenation of propane to propylene (PDH). It is characterized that the VSiBeta catalysts possess different kinds of vanadium species on the SiBeta support, including monomeric or isolated VOx species at a low V loading, and polynuclear VOx species in different polymerization degrees at higher V loadings. The 3VSiBeta catalyst (V loading is 3 wt%), containing isolated VOx species in monolayer, shows around 40% of propane conversion with 90% of propylene selectivity (reaction conditions:600 ℃, 4000 mL g-1 h-1) which are comparable to VSiBeta catalysts with higher V loadings. The catalytic activity exhibits a good linear relationship with the amount of generated acidic sites, which are derived from the interaction sites between VOx species and SiBeta support, and keeps stable after several regeneration cycles. Thus, as the VOx species directly contact with SiBeta support via V-O-Si bonds, a reactivity enhancement can be achieved. While, the initial valence state of V does not seem to influence the catalytic performance. Moreover, the aggregation degree of VOx species determines the propylene selectivity and deactivation rate, both of which increase as raising the V loading amount.

Key words: Propane dehydrogenation, Propylene, VOx species, SiBeta support, Active sites