Chinese Journal of Catalysis ›› 2017, Vol. 38 ›› Issue (11): 1925-1934.DOI: 10.1016/S1872-2067(17)62922-X

• Articles • Previous Articles    

Effects of surface physicochemical properties on NH3-SCR activity of MnO2 catalysts with different crystal structures

PiJun Gonga,c, JunLin Xiea,b,c, De Fanga,b, Da Hana,c, Feng Hea,c, FengXiang Lia,c, Kai Qia,c   

  1. a State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, Hubei, China;
    b Center for Materials Research and Analysis, Wuhan University of Technology, Wuhan 430070, Hubei, China;
    c School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China
  • Received:2017-08-24 Revised:2017-09-25 Online:2017-11-18 Published:2017-11-24
  • Contact: 10.1016/S1872-2067(17)62922-X
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (51502221).

Abstract:

α-, β-, δ-, and γ-MnO2 nanocrystals are successfully prepared. We then evaluated the NH3 selective catalytic reduction (SCR) performance of the MnO2 catalysts with different phases. The NOx conversion efficiency decreased in the order:γ-MnO2 > α-MnO2 > δ-MnO2 > β-MnO2. The NOx conversion with the use of γ-MnO2 and α-MnO2 catalysts reached 90% in the temperature range of 140-200℃, while that based on β-MnO2 reached only 40% at 200℃. The γ-MnO2 and α-MnO2 nanowire crystal morphologies enabled good dispersion of the catalysts and resulted in a relatively high specific surface area. We found that γ-MnO2 and α-MnO2 possessed stronger reducing abilities and more and stronger acidic sites than the other catalysts. In addition, more chemisorbed oxygen existed on the surface of the γ-MnO2 and α-MnO2 catalysts. The γ-MnO2 and α-MnO2 catalysts showed excellent performance in the low-temperature SCR of NO to N2 with NH3.

Key words: MnO2, Crystal structure, Surface-active oxygen, Selective catalytic reduction, Physicochemical property