Acta Phys. -Chim. Sin. ›› 2017, Vol. 33 ›› Issue (6): 1242-1252.doi: 10.3866/PKU.WHXB201703292

• ARTICLE • Previous Articles     Next Articles

Effects of CeO2 Addition on Improved NO Oxidation Activities of Pt/SiO2-Al2O3 Diesel Oxidation Catalysts

Yu-Fen HUANG1,Hai-Long ZHANG2,Zheng-Zheng YANG3,Ming ZHAO1,Mu-Lan HUANG1,Yan-Li LIANG1,Jian-Li WANG1,*(),Yao-Qiang CHEN1,*()   

  1. 1 Key Laboratory of Green Chemistry & Technology of the Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
    2 College of Chemical Engineering, Sichuan University, Chengdu 610064, P. R. China
    3 College of Environmental Science and Engineering, China West Normal University, Nanchong 637009, Sichuan Province, P. R. China
  • Received:2016-12-12 Published:2017-05-19
  • Contact: Jian-Li WANG,Yao-Qiang CHEN E-mail:wangjianli@scu.edu.cn;nic7501@scu.edu.cn
  • Supported by:
    The project was supported by the National Natural Science Foundation of China(21173153);National Hi-Tech Research and Development Program of China (863)(2015AA034603)

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Abstract:

The catalytic activities for NO oxidation achieved by different amounts of CeO2-modified Pt/SiO2-Al2O3 catalysts Pt/SiO2-Al2O3-wCeO2 (the mass fraction w being 0%, 5%, 10%, 15%, 30%), prepared using step-wise impregnation, were investigated in the presence and absence of CO and C3H6. The results showed that the NO oxidation activity could be efficiently improved by modification of CeO2, wherein the 15%-CeO2-modified catalyst exhibited the maximum NO conversion of 61% even in the presence of CO and C3H6, which were proved to inhibit NO2 formation in this study. A series of characterization methods were performed over the as-prepared samples to correlate their surface and structural characteristics with their enhanced NO oxidation activities. CO-chemisorption illustrated that appropriate CeO2-loading was effective for enhancing Pt dispersion, thus enhancing Pt surface-to-volume ratio, confirmed by transmission electron microscope (TEM) images. X-Ray Diffraction (XRD) further suggested that ceria addition could suppress the growth of the Pt crystal, resulting in higher surface Pt atomic ratio. Further, H2 temperature-programmed reduction (H2-TPR), together with TEM results, implied that the presence of ceria could enhance the interaction between metal and supports, thus facilitating reducibility of both active platinum and ceria. Hence, this study displays that ceria could act as a dispersion promoter and a reducibility booster, both of which are beneficial to NO oxidation activity. The improved NO oxidation activity is significant for the efficient purification of diesel integrated catalytic system.

Key words: CeO2-modified catalysts, Diesel oxidation catalysts, NO oxidation, Increased surface Pt atomic ratio, Pt-Ce interaction