Mo/HZSM-5催化剂表面活性中心的计算机模拟  

A simulation study of the active sites of Mo/HZSM-5 catalyst

作　　者：刘丹 张晓彤[2] 桂建舟[2] 宋丽娟[2] 孙兆林[1] 

机构地区：[1]石油大学(华东)化学化工学院,山东东营257061 [2]辽宁石油化工大学石油化工学院,辽宁抚顺113001

出　　处：《兰州大学学报（自然科学版）》2004年第6期59-63,共5页Journal of Lanzhou University(Natural Sciences)

基　　金：国家自然科学基金(20343006)辽宁省科学基金(002076)辽宁省教育厅攀登计划(20051016)资助项目.

摘　　要：用密度泛函理论中的广义梯度近似方法对催化剂活性中心的结构进行了优化,并对活性中心的电荷布居数、Mayer键级、Mayer总价态、振动频率和Fukui反应指数等性质进行了研究.结果表明最可能的钼活性中心为两个晶格氧担载的四面体配位结构,局部呈C2v对称.钼氧原子间的化学键具有离子性和共价性双重特点.用GGA方法计算的活性中心的振动频率与FTIR实验结果相一致.催化剂团簇的Fukui反应指数表明钼原子和端位氧原子是催化剂活性中心的反应部位.Gradient corrected density functional theory has been applied to the investigation of the structure and properties of the active sites of Mo/HZSM-5 catalysts including vibrational frequency, population, Fukui indices and so on. It is shown that Mo can be bonded with two bridging oxygen atoms of HZSM-5 forming a tetrahedral MoO4 structure with a C2v symmetry. The interatomic binding between Mo and oxygen atoms is the combination of both ionic and covalent contribution. The double bonds between Mo and extra-framework oxygen atoms exhibit a strong covalent character while the binding between Mo and framework oxygen shows more ionic feature. Vibrational spectra of the Mo active centers calculated using DFT-GGA method are in an excellent agreement with FTIR experimental data. Fukui index analysis indicates that Mo atom and extra-framework oxygen atoms are the most active sites to trigger the C-H of methane dissociated.

关 键 词：密度泛函理论 广义梯度近似 分子模拟 

分 类 号：O641[理学—物理化学]