Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (10): 1895-1902.doi: 10.3866/PKU.WHXB201407162

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Structural Properties and Low-Temperature SCR Activity of Zirconium-Modified MnOx/MWCNTs Catalysts

YANG Chao1, LIU Xiao-Qing1, HUANG Bi-Chun1,2, WU You-Ming3   

  1. 1. College of Environment and Energy, South China University of Technology, Guangzhou 510006, P. R. China;
    2. Key Laboratory of the Ministry of Education for Pollution Control and Ecosystem Restoration in Industry Clusters, South China University of Technology, Guangzhou 510006, P. R. China;
    3. Guangzhou Research Institute of Environmental Protection, Guangzhou 510620, P. R. China
  • Received:2014-06-17 Revised:2014-07-14 Published:2014-09-30
  • Contact: HUANG Bi-Chun E-mail:cebhuang@scut.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (209077034).

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Abstract:

A series of ZrO2/MWCNTs were prepared, using ZrO(NO3)2·2H2O as a precursor, by the surface modification of multiwalled carbon nanotubes (MWCNTs). Manganese oxides were supported on the ZrO2/ MWCNTs to prepare MnOx/ZrO2/MWCNTs catalysts. The effect of zirconium on the selective catalytic reduction (SCR) activity of the catalysts was investigated. Furthermore, the structural properties of the catalysts were comprehensively characterized by a suite of analytical methods. The results show that the addition of zirconium improved the SCR activity of the MnOx/MWCNTs significantly and the catalyst with 30% Zr loading was found to have the highest activity. X- ray powder diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), and N2 adsorption-desorption results revealed that the modification of zirconium could enhance the dispersion of MnOx on the support as well as enhance the interaction between the metal oxides and the MWCNTs. Additionally, zirconium could also increase the specific surface area, the total pore volume, and the average pore size of the catalysts. Moreover, from the results of X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), and temperature-programmed desorption of NH3 (NH3- TPD), zirconium increased the atomic concentration of the chemisorbed oxygen on the catalysts surface and promoted the conversion of Mn3+ to Mn4+. Therefore, the surface-active sites increased and the redox ability of the catalysts improved. Additionally, the amount and strength of acid on catalyst surface increased. These factors are the main reason for the MnOx/ZrO2/MWCNTs catalysts having better low-temperature SCR activity.

Key words: Selective catalytic reduction, Nitrogen oxide, Zirconium, Manganese oxide, Multi-walled carbon nanotube