物理化学学报 >> 2011, Vol. 27 >> Issue (02): 329-336.doi: 10.3866/PKU.WHXB20110226

理论与计算化学 上一篇    下一篇

二元铜族团簇负离子催化CO氧化反应机理

胡建平1, 王俊2, 唐典勇1, 伏秦超1, 张元勤1   

  1. 1. 乐山师范学院化学与生命科学学院分子设计中心, 四川 乐山 614000;
    2. 成都军区总医院神经内科, 成都 610083
  • 收稿日期:2010-08-25 修回日期:2010-11-29 发布日期:2011-01-25
  • 通讯作者: 唐典勇 E-mail:qchem@189.cn
  • 基金资助:

    教育部科学技术研究重点项目(210189), 四川省自然科学基金(2008JY0119)和四川省教育厅(07ZA158)资助

Reaction Mechanisms of CO Oxidation Catalyzed by Binary Copper Group Cluster Anions

HU Jian-Ping1, WANG Jun2, TANG Dian-Yong1, FU Qin-Chao1, ZHANG Yuan-Qin1   

  1. 1. Molecular Design Center, College of Chemistry and Life Science, Leshan Normal University, Leshan 614000, Sichuan Province, P. R. China;
    2. Neurology Department, Chengdu Military General Hospital, Chengdu 610083, P. R. China
  • Received:2010-08-25 Revised:2010-11-29 Published:2011-01-25
  • Contact: TANG Dian-Yong E-mail:qchem@189.cn
  • Supported by:

    The project was supported by the Key Project of Chinese Ministry of Education (210189), Science and Technology Bureau of Sichuan Province, China (2008JY0119), and Education Bureau of Sichuan Province, China (07ZA158).

摘要:

用密度泛函理论B3LYP方法研究了二元铜族团簇负离子AuAg-, AuCu-和AgCu-催化CO氧化反应的详细机理. 计算结果表明: CO在混合团簇中的吸附位顺序为Cu>Au>Ag; O2也优先吸附到Cu上, 其次为Ag, 最难的为Au; 另外, O2分子较CO分子易于吸附到混合团簇上. CO氧化反应有三条反应通道, 在热力学和动力学上均容易进行. AuAg-团簇催化CO氧化反应的最优反应通道为CO插入AuAgO2-中的Ag―O键形成中间体[Au―AgC(O―O)O]-, 然后直接分解形成CO2和AuAgO-, 或另一个CO分子进攻中间体[Au―AgC(O―O)O]-形成两分子的CO2和AuAg-. 而AuCu-和AgCu-催化CO氧化反应的最优反应通道为CO和O2共吸附到团簇上,然后形成四元环中间体,最后四元环中间体分解形成产物或另一个CO分子进攻四元环中间体从而形成产物. 第二个CO分子的协同效应不明显. AuAg-和AuCu-对CO氧化反应催化活性强于Au2-团簇, 因此, Ag和Cu掺杂可以提高金团簇的催化活性, 与之前实验研究结果一致.

关键词: 密度泛函理论, CO氧化, 二元铜族团簇负离子, 反应机理

Abstract:

The detailed mechanisms of CO oxidation catalyzed by AuAg-, AuCu-, and AgCu- were investigated using density functional theory at the B3LYP level. The computational results indicate that the adsorption site of CO onto the mixed clusters decreases as follows: Cu>Au>Ag. Copper is the preferred adsorption site for O2 on the binary clusters. The adsorption of O2 onto gold was found to be the weakest. Three reaction pathways exist for CO oxidation catalyzed by AuAg-, AuCu-, and AgCu-. The most feasible pathway for CO oxidation catalyzed by AuAg- is CO insertion into the Ag―O bond of AuAgO2- to produce the [Au―AgC(O―O)O]- intermediate, which then decomposes into CO2 and AuAgO-, or another CO molecule attacks [Au―AgC(O―O)O]- to form two CO2 molecules and AuAg- anion. A feasible pathway for CO oxidation catalyzed by AuCu- or AgCu- is initiated by the co-absorption of CO and O2 onto the clusters followed by the formation of a four-membered ring intermediate to produce the corresponding products. The cooperation effect of the second CO is very weak. The catalytic activities of AuAg- and AuCu- toward CO oxidation are stronger than that of Au2- . Doping the Au clusters with Ag and Cu increases the catalytic activity. These results are in agreement with the previous experimental results.

Key words: Density functional theory, CO oxidation, Binary copper group cluster anion, Reaction mechanism

MSC2000: 

  • O641