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 Mller-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.
出处
《分子催化》
EI
CAS
CSCD
北大核心
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).
关键词
水分子吸附
氧化钼
脱氧剂
原子簇
密度泛函
Water Molecular Adsorption
MoO_3
Deoxidizing Catalyst
Cluster Model
Density Functional Theory (DFT)
