Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (03): 681-685.doi: 10.3866/PKU.WHXB201111141

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Promotional Effect of Cerium Oxide on the Catalytic Properties of Ce-Mn-Ti-O Catalysts for Selective Catalytic Reduction of NO

ZHUANG Ke, QIU Jing, XU Bo-Lian, FAN Yi-Ning   

  1. Key Laboratory of Mesoscopic Chemistry of Ministry of Education, Jiangsu Key Laboratory of Vehicle Emissions Control, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
  • Received:2011-08-17 Revised:2011-12-26 Published:2012-02-23
  • Contact: FAN Yi-Ning E-mail:ynfan@nju.edu.cn

Abstract: The promotional effect of cerium oxide on the catalytic properties of Ce-Mn-Ti-O composite oxide catalysts prepared by the sol-gel method was studied using NH3-temperature programmed desorption (NH3-TPD), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and BET surface area measurements combined with microreactor tests of NO selective catalytic reduction (SCR). The results showed that the addition of a cerium oxide component remarkably increased the low-temperature SCR activity of Mn-Ti-O composite oxide catalyst. When the cerium content was increased, NO conversion increased significantly and reached a maximum around Ce/Mn molar ratio of 0.08. Further increases in the cerium content resulted in a decrease in NO conversion over the catalyst. The experimental results indicated that the addition of a cerium oxide component does not influence the surface acidity of Mn-Ti-O composite oxide catalyst, but increases the surface concentration of catalytically active Mn species, the relative content of Mn4+, and the reducibility of Mn species, leading to an increase in the SCR activity of Ce-Mn-Ti-O composite oxide catalysts. When the Ce/Mn molar ratio was greater than 0.08, the formation of amorphous multilayer Ce-O-Mn species composed of Ce and Mn species may reduce the Mn/Ti molar ratio and the reducibility of Mn species, leading to a decrease in the SCR activity of Ce-Mn-Ti-O composite oxide catalysts.

Key words: Cerium oxide, Manganese oxide, Titania, Nitric oxide, Selective catalytic reduction

MSC2000: 

  • O643