水分子在MoO_3原子簇模型表面吸附的密度泛函研究  

Density Functional Theoretical Study of Water Molecular Adsorption on the Surface of MoO_3 with the Cluster Model

作　　者：刘够生[1,2] 宋兴福[2] 汪瑾[2] 于建国[2] 

机构地区：[1]江西科技师范学院应用化学系,江西南昌330013 [2]华东理工大学资源化利用与工程研究室

出　　处：《分子催化》2005年第2期136-140,共5页Journal of Molecular Catalysis(China)

基　　金：中葡第四届科技混委会项目暨上海市国际合作项目(项目编号:025207009).

摘　　要：利用密度泛函理论(DFT)的B3LYP方法,在LANL2DZ基组上,计算了水分子吸附前后MoO3原子簇模型物的优化几何构型和电子结构,并进行了二级M ller-Plesset微扰(MP2)相关能计算.结果表明,当水分子吸附于模型分子后,由于占据了MO5+空位,从原来留有空位的MoO5H4模型转变为MoO5H4·H2O模型的正八面体构型,水分子的氧通过占据在π键轨道中的电子向中心原子Mo的d轨道配位而被吸附,且水分子在模型物质表面呈吸附状态后,体系最稳定,能量最小,吸附过程不必翻越能垒,该过程放热91.39kJ/mol(MP2相关能校正),研究结果对催化剂的使用、失活和再生有较好的指导意义.Density functional theory (DFT) on the LANL2DZ level was used to optimize the geometry and electronic structures of MoO_3 cluster model before and after water molecular adsorption on its surface. The electron correlation energies of the optimized structures were also calculated applying the second order Mller-Plesset perturbation theory (MP2). The results show that when water molecule was adsorbed on the model surface, it occupied the vacant site of MO^(5+), with conformation transforming from model MoO_5H_4 to octahedral complex of model MoO_5H_4·H_2O. Water molecule was adsorbed by the process of π electrons of atom O in water molecule coordinated with electrons in d orbital of the central Mo atom. During this process, there was a minimum point on the potential energy surface without passing any energy barrier for the whole adsorption process. The process was an exothermal reaction, with adsorption heat -91.39 kJ/mol. The results are significant for studies on the use, deactivation and reactivation of this deoxidizing catalyst.

关 键 词：水分子吸附 氧化钼 脱氧剂 原子簇 密度泛函 

分 类 号：O643[理学—物理化学]