物理化学学报 >> 2012, Vol. 28 >> Issue (03): 681-685.doi: 10.3866/PKU.WHXB201111141

催化和表面科学 上一篇    下一篇

NO选择性催化还原Ce-Mn-Ti-O催化剂铈组分助催化作用

庄柯, 裘婧, 许波连, 范以宁   

  1. 南京大学化学化工学院, 介观化学教育部重点实验室, 江苏省机动车尾气污染控制重点实验室, 南京 210093
  • 收稿日期:2011-08-17 修回日期:2011-12-26 发布日期:2012-02-23
  • 通讯作者: 范以宁 E-mail:ynfan@nju.edu.cn

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

摘要: 用NH3 程序升温脱附(NH3-TPD)、X 射线衍射(XRD)、X 射线光电子能谱(XPS)、H2 程序升温还原(H2-TPR)和BET表面积测试结合NO选择性催化还原(SCR)微型反应评价等方法, 研究了溶胶-凝胶法制备的Ce-Mn-Ti-O 复合氧化物催化剂中铈组分的助催化作用. 结果表明随铈含量增加, NO转化率大幅度增加, 在Ce/Mn 摩尔比约0.08 时达极大值, 其后随铈含量进一步增加, NO 转化率又逐渐下降. 适量铈组分的加入对Mn-Ti-O 催化剂表面酸性影响不大, 但增加了催化剂活性组分Mn物种的表面浓度, 提高了Mn4+物种的相对含量和Mn物种的可还原性, 从而提高催化剂低温SCR活性. 当Ce/Mn摩尔比超过0.08, 催化剂表面的Mn组分与Ce组分可能形成无定型结构的多层聚集的Ce-O-Mn物种, 导致催化剂Mn/Ti 摩尔比下降和Mn物种可还原性下降, 从而导致催化剂SCR活性的下降.

关键词: 氧化铈, 氧化锰, 氧化钛, 氮氧化物, 选择性催化还原

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