Chinese Journal of Catalysis

Chinese Journal of Catalysis ›› 2017, Vol. 38 ›› Issue (5): 813-820.DOI: 10.1016/S1872-2067(17)62817-1

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Effect of Pd doping on CH4 reactivity over Co3O4 catalysts from density-functional theory calculations

Chengcheng Zhaoa,b,c, Yonghui Zhaoa, Shenggang Lia,c, Yuhan Suna,c   

  1. a. CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China;
    b. University of Chinese Academy of Sciences, Beijing 100049, China;
    c. School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
  • Received:2017-01-27 Revised:2017-02-24 Online:2017-05-18 Published:2017-05-10
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21473233, 21403277) and the Energy Technologies Institute LLP, UK.

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Abstract:

Palladium oxide (PdOx) and cobalt oxide (Co3O4) are efficient catalysts for methane (CH4) combustion, and Pd-doped Co3O4 catalysts have been found to exhibit better catalytic activities, which suggest synergism between the two components. We carried out first-principles calculations at the PBE+U level to investigate the Pd-doping effect on CH4 reactivity over the Co3O4 catalyst. Because of the structural complexity of the Pd-doped Co3O4 catalyst, we built Pd-doped catalyst models using Co3O4(001) slabs with two different terminations and examined CH4 reactivity over the possible Pd-O active sites. A low energy barrier of 0.68 eV was predicted for CH4 dissociation over the more reactive Pd-doped Co3O4(001) surface, which was much lower than the 0.98 and 0.89 eV that was predicted previously over the more reactive pure Co3O4(001) and (011) surfaces, respectively. Using a simple model, we predicted CH4 reaction rates over the pure Co3O4(001) and (011) surfaces, and Co3O4(001) surfaces with different amounts of Pd dopant. Our theoretical results agree well with the available experimental data, which suggests a strong synergy between the Pd dopant and the Co3O4 catalyst, and leads to a significant increase in CH4 reaction rate.

Key words: Spinel cobalt oxide, Palladium dopant, Methane combustion, Density function theory calculation, Reaction rate, Collision theory