Ag_2^-催化CO氧化反应机理的理论研究  

Theoretical Study on Mechanism of CO Oxidation Catalyzed by Ag_2^-

作　　者：唐典勇[1] 胡建平[1] 张元勤[1] 胡常伟[2] 

机构地区：[1]乐山师范学院化学与生命科学学院,乐山614000 [2]四川大学化学学院,成都610064

出　　处：《化学学报》2009年第16期1859-1864,共6页Acta Chimica Sinica

基　　金：四川省自然科学基金(No2008JY0119);四川教育厅(No07ZA158)资助项目

摘　　要：用密度泛函理论B3LYP方法详细研究了Ag_2^-催化CO氧化反应的机理.计算结果表明,O2分子在Ag_2^-和Au_2^-上吸附能相差不大,而CO分子在Ag_2^-上吸附要比在Ag_2^-上弱得多.Ag_2^-催化CO氧化反应共有四条反应途径.最可能反应通道为CO插入Ag2O_2^-中的Ag—O键形成中间体[Ag—AgC(O—O)O]-,然后直接分解形成产物CO2和Ag2O-,或另一分子CO进攻中间体[Ag—AgC(O—O)O]-形成两分子产物CO2和Ag_2^-.在动力学上最难进行的反应通道为经历碳酸根双银中间体,需要克服约0.24eV的能垒.Ag_2^-催化CO氧化反应活性要高于Au_2^-.The mechanism of Ag-2 -catalyzed CO oxidation was investigated at the level of B3LYP theory. The computational results indicate that the absorption energy of O2 on Ag-2 is close to that of O2 on Au-2 , while the absorption of CO on Ag-2 is stronger than that of CO on Au-2 . There are four reaction pathways for CO oxidation catalyzed by Ag-2 . The most feasible pathway is the CO insertion into the Ag-O bond of Ag 2 O-2 to produce an intermediate [Ag-AgC（O-O）O]-, and then the intermediate [Ag-AgC（O-O）O]decomposes into product CO2 and Ag2O-, or another CO molecule attacks [Ag--AgC（O---O）O]- to form two CO2 molecules and Ag2^- anion. The most difficult pathway is the di-silver carbonate intermediate pathway, which needs to overcome a total energy barrier of about 0.24 eV. Since for gold, the carbonate-like intermediate pathway requires an activation barrier of 0.61 eV, silver proves to be a better catalyst than gold.

关 键 词：阴离子银团簇 CO氧化反应 反应机理 密度泛函理论 

分 类 号：O643.12[理学—物理化学]