Chinese Journal of Catalysis

Chinese Journal of Catalysis ›› 2017, Vol. 38 ›› Issue (1): 146-159.DOI: 10.1016/S1872-2067(16)62572-X

• Article • Previous Articles     Next Articles

Influence of preparation methods on the physicochemical properties and catalytic performance of MnOx-CeO2 catalysts for NH3-SCR at low temperature

Xiaojiang Yaoa, Kaili Mab, Weixin Zoub, Shenggui Hec, Jibin And, Fumo Yanga,e, Lin Dongb   

  1. a Key Laboratory of Reservoir Aquatic Environment of CAS, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China;
    b Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, Jiangsu, China;
    c Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
    d Chongqing Key Laboratory of Environmental Materials and Remediation Technology, Chongqing University of Arts and Sciences, Chongqing 402160, China;
    e Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, Fujian, China
  • Received:2016-09-01 Revised:2016-09-28 Online:2017-01-18 Published:2017-01-18
  • Contact: Xiaojiang Yao,Tel:+86-23-65935909;Fax:+86-23-65935924;E-mail:yaoxj@cigit.ac.cn;Fumo Yang,Tel:+86-23-65935909;Fax:+86-23-65935924;E-mail:fmyang@cigit.ac.cn;Lin Dong,Tel:+86-25-83592290;Fax:+86-25-83317761;E-mail:donglin@nju.edu.cn
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (No. 21507130); the Open Project Program of Beijing National Labor-atory for Molecular Sciences (No. 20140142); the Open Project Program of Chongqing Key Laboratory of Environmental Materials and Remediation Technology from Chongqing University of Arts and Sciences (No. CEK1405); the Open Project Program of Jiangsu Key Laboratory of Vehicle Emissions Control (No. OVEC001); the Open Project Program of Chongqing Key Laboratory of Catalysis and Functional Organic Molecules from Chongqing Technology and Business University (1456029); and the Chongqing Science & Technology Commission (Nos. cstc2016jcyjA0070, cstc2014pt-gc20002, cstckjcxljrc13).

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Abstract:

This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx-CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3-SCR) at low temperature. Five different methods, namely, mechanical mixing, impregnation, hydrothermal treatment, co-precipitation, and a sol-gel technique, were used to synthesize MnOx-CeO2 catalysts. The catalysts were characterized in detail, and an NH3-SCR model reaction was chosen to evaluate the catalytic performance. The results showed that the preparation methods affected the catalytic performance in the order:hydrothermal treatment > sol-gel > co-precipitation > impregnation > mechanical mixing. This order correlated with the surface Ce3+ and Mn4+ content, oxygen vacancies and surface adsorbed oxygen species concentration, and the amount of acidic sites and acidic strength. This trend is related to redox interactions between MnOx and CeO2. The catalyst formed by a hydrothermal treatment exhibited excellent physicochemical properties, optimal cata-lytic performance, and good H2O resistance in NH3-SCR reaction. This was attributed to incorpora-tion of Mnn+ into the CeO2 lattice to form a uniform ceria-based solid solution (containing Mn-O-Ce structures). Strengthening of the electronic interactions between MnOx and CeO2, driven by the high-temperature and high-pressure conditions during the hydrothermal treatment also improved the catalyst characteristics. Thus, the hydrothermal treatment method is an efficient and environ-ment-friendly route to synthesizing low-temperature denitrification (deNOx) catalysts.

Key words: MnOx-CeO2 catalyst, Preparation method, Nitrogen oxides, Low-temperature NH3-SCR, Electron interaction, Surface acidity