催化学报

催化学报 ›› 2011, Vol. 32 ›› Issue (3): 477-482.DOI: 10.3724/SP.J.1088.2011.00832

• 研究论文 • 上一篇    下一篇

共沉淀法制备 Cr-Mn 复合氧化物及其低温催化还原 NOx 性能

李雪辉, 李华, 高翔, 陈志航, 杨青, 王芙蓉, 王乐夫   

  1. 华南理工大学化学与化工学院, 广东广州 510640
  • 收稿日期:2010-07-30 修回日期:2010-12-21 出版日期:2011-03-04 发布日期:2014-08-01

Preparation of Cr-Mn Mixed Oxide by Coprecipitation and Its Performance for Low-Temperature Selective Catalytic Reduction of NOx

LI Xuehui*, LI Hua, GAO Xiang, CHEN Zhihang, YANG Qing, WANG Furong, WANG Lefu   

  1. School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, Guangdong, China
  • Received:2010-07-30 Revised:2010-12-21 Online:2011-03-04 Published:2014-08-01

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摘要： 采用共沉淀法制备了一系列具有 CrMn1.5O4 晶相的新型 Cr-Mn 复合氧化物催化剂并用于低温有氧条件下氨选择性催化还原 (SCR)NOx. 结果表明, NOx 转化率随着 Cr/(Cr+Mn) 摩尔比从 0.1 到 0.4 的增加而升高. 其中 Cr(0.4)-MnOx 具有较高的低温活性, 在 140 oC, 空速为 30 000 h-1 的条件下, NOx 转化率可高达 90%. 利用 N2 吸附法, X 射线衍射及 X 射线光电子能谱对系列催化剂进行了表征, 发现通过添加 Cr 元素, 可形成新型  CrMn1.5O4 活性物相; 由于 Cr 元素对催化剂表面电子性能具有调变作用, Mn 元素主要以高氧化态形式 Mn4+ 及 Mn3+ 富集, 不仅可以促进对 NO 的氧化, 而且有利于对 NH3 的吸附和活化, 从而使该催化剂具有较好的低温 SCR 活性.

关键词: 共沉淀, 氮氧化物, 选择性催化还原, 氨, 低温, 铬, 锰

Abstract: A series of Cr-Mn mixed-oxide catalysts comprising a novel CrMn1.5O4 crystal phase were prepared by the coprecipitation method and applied to low-temperature selective catalytic reduction (SCR) of NOx with NH3 in the presence of O2. The experimental results showed that the NOx conversion increased with the increase of Cr content and peaked at the Cr(0.4)-MnOx catalyst with the molar ratio of Cr/(Mn+Cr) = 0.4, which yielded nearly 90% NOx conversion at 140 oC with a high space velocity of 30 000 h-1. The characterization of N2 adsorption, X-ray diffraction, and X-ray photoelectron spectroscopy indicated that the addition of Cr generated the novel CrMn1.5O4 crystal phase and adjusted the surface electronic properties, leading to the enrichment of higher oxidation states Mn4+ and Mn3+ on the surface. This promotes the oxidation of NO and is helpful for the adsorption of NH3, so that the catalyst exhibits higher low-temperature SCR activity.

Key words: coprecipitation, nitrogen oxide, selective catalytic reduction, ammonia, low-temperature, chrome, manganese