Chinese Journal of Catalysis ›› 2020, Vol. 41 ›› Issue (3): 442-453.DOI: 10.1016/S1872-2067(19)63480-7

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Co-Cr-O mixed oxides for low-temperature total oxidation of propane: Structural effects, kinetics, and spectroscopic investigation

Wen-Min Liao, Pei-Pei Zhao, Bing-Heng Cen, Ai-Ping Jia, Ji-Qing Lu, Meng-Fei Luo   

  1. Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, China
  • Received:2019-07-07 Revised:2019-08-02 Online:2020-03-18 Published:2019-11-19
  • Supported by:
    This work was financially supported by the National Natural Science Foundation of China (21773212, 21872124).

Abstract: A series of Co-Cr-O mixed oxides with different Co/Cr molar ratios are synthesized and tested for the total oxidation of propane. The reaction behaviors are closely related to the structural features of the mixed oxides. The catalyst with a Co/Cr molar ratio of 1:2 (1Co2Cr) and a spinel structure has the best activity (with a reaction rate of 1.38 μmol g-1 s-1 at 250℃), which is attributed to the synergistic roles of its high surface acidity and good low-temperature reducibility, as evidenced by the temperature-programmed desorption of ammonia, reduction of hydrogen, and surface reaction of propane. Kinetic study shows that the reaction orders of propane and oxygen on the 1Co2Cr catalyst (0.58 ± 0.03 and 0.34 ±0.05, respectively) are lower than those on the 2Co1Cr catalyst (0.77 ±0.02 and 0.98 ±0.16, respectively) and 1Co5Cr (0.66 ±0.05 and 1.30 ±0.11, respectively), indicating that the coverages of propane and oxygen on 1Co2Cr are higher than those on the other catalysts due to its higher surface acidity and higher reducibility. In addition, in-situ diffuse reflectance infrared spectroscopic investigation reveals that the main surface species on 1Co2Cr during the reaction are polydentate carbonate species, which accumulate on the surface at low temperatures (< 250℃) but decompose at relatively high temperatures.

 

Key words: Propane combustion, Co-Cr mixed oxides, Reducibility, Surface acidity, Kinetics

CLC Number: