物理化学学报 >> 2007, Vol. 23 >> Issue (05): 664-670.doi: 10.3866/PKU.WHXB20070509

研究论文 上一篇    下一篇

Co-M(M=La, Ce, Fe, Mn, Cu, Cr)复合金属氧化物催化分解N2O

薛莉; 贺泓   

  1. 中国科学院生态环境研究中心, 环境化学与生态毒理学国家重点实验室, 北京 100085
  • 收稿日期:2006-10-08 修回日期:2006-12-27 发布日期:2007-04-28
  • 通讯作者: 贺泓 E-mail:honghe@rcees.ac.cn

Catalytic Decomposition of N2O over Co-M(M=La, Ce, Fe, Mn, Cu, Cr) Composite Oxide Catalysts

XUE Li; HE Hong   

  1. State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, P. R. China
  • Received:2006-10-08 Revised:2006-12-27 Published:2007-04-28
  • Contact: HE Hong E-mail:honghe@rcees.ac.cn

PDF

4557

赞

摘要： 通过共沉淀法制备了一系列Co-M(M= La, Ce, Fe, Mn, Cu, Cr)复合金属氧化物及纯Co3O4催化剂, 考察了其催化分解N2O 的活性. 结果表明在研究的系列催化剂中, Co-Ce 复合氧化物催化剂具有最好的催化分解N2O的活性; 其活性与Ce/Co 摩尔比有直接的关系, 当Ce/Co 摩尔比为0.05 时(CoCe0.05 催化剂)催化活性最佳; 当有NO 和O2共存时, 可能在催化剂活性中心上形成表面硝酸盐或亚硝酸盐吸附物种而使其活性受到较大影响. 通过对Co-M 催化剂的XRD、BET、O2-TPD及H2-TPR 等表征结果的分析, 发现作为主要活性位的Co2+的氧化还原能力是影响催化剂活性的主要原因. 这是因为根据反应机理, N2O 的表面分解步骤与Co2+氧化成Co3+的能力相关, 而吸附氧的脱附与Co3+还原成Co2+的能力相关. 在所研究的催化剂中, 添加除CeO2之外的其它过渡金属氧化物时, 催化剂中Co3+/Co2+的氧化还原能力降低, 因此其催化性能降低. 另外, 添加不同过渡金属氧化物也改变了N2O 催化分解反应的速控步骤.

关键词: 四氧化三钴, 二氧化铈, 尖晶石, 氧化亚氮催化分解, 复合金属氧化物催化剂

Abstract: A series of Co-M (M=La, Ce, Fe, Mn, Cu, Cr) composite oxide catalysts were prepared by co-precipitation method and tested in catalytic decomposition of N2O. The results showed that Co-Ce composite oxide with Ce/Co molar ratio of 0.05 (CoCe0.05 catalyst) performed best in the N2O decomposition reaction. The presence of NO and O2 in the feed affected the decomposition rate of N2O over CoCe0.05 by adsorption of nitrate or nitrite species on the active site. The XRD, BET, O2-TPD, and H2-TPR methods were used to characterize the Co-Mmixed catalysts. The analysis results showed that the redox ability of the active site (Co2+) was very important for the decomposition of N2O over these catalysts. The surface decomposition of N2O was accompanied by the oxidation of Co2+ to Co3+, and the desorption of surface oxygen was accompanied by the reduction of Co3+ to Co2+. The addition of other transition metal oxides except CeO2 lowered the redox ability of Co3 +/Co2 +, and thus lowered the catalytic activities for the decomposition of N2O. In addition, the rate-determining step of the catalytic N2O decomposition was also influenced by the addition of various metal oxides.

Key words:

Co3O4, CeO2, Spinel, Catalytic decomposition of N2O, Composite oxide catalyst