Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (4): 750-756.doi: 10.3866/PKU.WHXB201502051

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Effects of H2O and O2 on the Reaction of NO Reduction by CH4 under Stoichiometric Natural Gas Vehicles

SHANG Hong-Yan1, HU Wei1, WANG Yun2, REN Cheng-Jun3, GONG Mao-Chu3, CHEN Yao-Qiang1,3   

  1. 1 College of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China;
    2 Sichuan Zhongzi Exhaust Gas Cleaning Co., Ltd., Chengdu 611731, P. R. China;
    3 Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
  • Received:2014-11-02 Revised:2015-02-04 Published:2015-04-03
  • Contact: CHEN Yao-Qiang E-mail:nic7501@scu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21173153), Project from Sichuan Provincial Environment Office, China (2011HB002), and Science and Technology Support Project of Science and Technology Department of Sichuan Province, China (2012FZ0008).

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Abstract:

Composite support CeZrYLa + LaAl was prepared by co-precipitation, and platinum catalyst supported on the composite support was prepared by impregnation. The behavior of the Pt catalyst for the reaction of NO reduction by CH4 from the exhausts of natural gas vehicles (NGVs) was studied under stoichiometric conditions. Additionally, the effects of 10% (volume fraction, φ) H2O and stoichiometric O2 on the reaction in the presence of CO2 were also investigated. Results show that N2 and CO2 were the main products for the different reactions, CO was detected under high temperature, and NOx was detected under low temperature (in the presence of O2, the NOx was NO2, whereas the NOx was N2O when no O2 was present). In the presence of 10% (φ) H2O, the conversion of CH4 noticeably decreased and NO conversion remained unchanged, possibly because the presence of H2O weakens the reforming reaction of CH4 with CO2, but does not affect the activity of NO reduction by CH4. In the presence of stoichiometric O2, there was an obvious increase of CH4 conversion and a decrease of NO conversion. These could be explained by the competition between NO and O2, where the oxidation of methane by O2 is the main reaction, limiting the reaction of NO reduction by CH4. Moreover, in the presence of 10% (φ) H2O and stoichiometric O2, CO2 reforming of CH4 was negligible. Numerous reactions were detected simultaneously, such as the oxidation of CH4 by NO, steam reforming of CH4, and the reduction of NO by CH4, thus improving the conversions of CH4 and NO.

Key words: Pt, CeZrYLa+LaAl, Gas composition, Reduction of NO by CH4, Natural gas vehicle exhaust purification