Chinese Journal of Catalysis ›› 2016, Vol. 37 ›› Issue (8): 1293-1302.DOI: 10.1016/S1872-2067(15)61119-6

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SnO2-based solid solutions for CH4 deep oxidation: Quantifying the lattice capacity of SnO2 using an X-ray diffraction extrapolation method

Qi Sun, Xianglan Xu, Honggen Peng, Xiuzhong Fang, Wenming Liu, Jiawei Ying, Fan Yu, Xiang Wang   

  1. College of Chemistry, Nanchang University, Nanchang 330031, Jiangxi, China
  • Received:2016-02-28 Revised:2016-04-22 Online:2016-07-29 Published:2016-08-01
  • Contact: Xiang Wang
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21263015, 21567016 and 21503106), the Education Department Foundation of Jiangxi Province (KJLD14005 and GJJ150016), and the Natural Science Foundation of Jiangxi Province (20142BAB213013 and 20151BBE50006), which are greatly acknowledged by the authors.

Abstract:

A series of SnO2-based catalysts modified by Mn, Zr, Ti and Pb oxides with a Sn/M (M = Mn, Zr, Ti and Pb) molar ratio of 9/1 were prepared by a co-precipitation method and used for CH4 and CO oxidation. The Mn3+, Zr4+, Ti4+ and Pb4+ cations are incorporated into the lattice of tetragonal rutile SnO2 to form a solid solution structure. As a consequence, the surface area and thermal stability of the catalysts are improved. Moreover, the oxygen species of the modified catalysts become easier to be reduced. Therefore, the oxidation activity over the catalysts was improved, except for the one modified by Pb oxide. Manganese oxide demonstrates the best promotional effects for SnO2. Using an X-ray diffraction extrapolation method, the lattice capacity of SnO2 for Mn2O3 was 0.135 g Mn2O3/g SnO2, which indicates that to form stable solid solution, only 21% Sn4+ cations in the lattice can be maximally replaced by Mn3+. If the amount of Mn3+ cations is over the capacity, Mn2O3 will be formed, which is not favorable for the activity of the catalysts. The Sn rich samples with only Sn-Mn solid solution phase show higher activity than the ones with excess Mn2O3 species.

Key words: SnO2-based solid solution, X-ray diffraction extrapolation method, Lattice capacity, Methane deep oxidation, Carbon monoxide oxidation