Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (5): 1236-1246.doi: 10.3866/PKU.WHXB201602251

• ARTICLE • Previous Articles     Next Articles

Preparation, Characterization and Low-Temperature NH3-SCR Activity of MnOx/SAPO-11 Catalysts

Xiao-Qing LIU1,Shi-Hui LI1,Meng-Ting SUN1,Cheng-Long YU1,Bi-Chun HUANG1,2,*()   

  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
  • Received:2015-11-23 Published:2016-05-07
  • Contact: Bi-Chun HUANG E-mail:cebhuang@scut.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(51478191);Guangdong Provincial Science and Technology Project, China(2014A020216003)

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Abstract:

MnOx/SAPO-11 catalysts were prepared by impregnation, citric acid, and precipitation methods for low-temperature selective catalytic reduction (SCR) of NO with NH3. The results indicated that the MnOx/SAPO-11 catalyst with 20%(w) Mn loading prepared by the precipitation method showed the best SCR activity and N2 selectivity. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), atomic absorption spectrometry (AAS), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), NH3 temperature-programmed desorption (NH3-TPD), NO/O2 temperature-programmed desorption, and mass spectrometry (NO/O2-TPD-MS) were used to analyze the structural properties and catalytic performance of the catalysts. The results indicated that different manganese oxides were formed on the surface of SAPO-11 by the three different preparation methods. MnOx loaded via the precipitation method existed as MnO2 phase and amorphous MnOx. The advantages of the catalyst prepared via this method were a large mesoporous and external surface area, the highest content of chemisorbed oxygen and Mn4+ as well as more favorable medium and strong acid sites. Thus, more NO2 was produced on the catalyst during low-temperature SCR, which was a primary goal. MnOx prepared by all three methods could be well-dispersed on the surface of SAPO-11. The dispersive action of SAPO-11 could affect the formation of MnOx, which could affect the acidity of the catalysts. Thus, the temperature window was widened and N2 selectivity was improved compared with pure MnOx, with SAPO-11 acting as an excellent carrier.

Key words: Selective catalytic reduction, Nitrogen oxide, SAPO-11 molecular sieve, Precipitation method, Manganese oxide