Pt_(18)团簇催化肉桂醛选择性加氢反应机理研究

Investigation on the Mechanism for Cinnamic Aldehyde Selective Hydrogenation Reaction Catalyzed by Pt_(18) Cluster

采用密度泛函理论(DFT)中的B3LYP方法,在6-31+G(d,p)基组水平上,重点研究Pt_(18)团簇对肉桂醛选择性加氢反应的催化作用.对反应通道上反应物、中间体、过渡态和产物进行结构优化.通过能量和振动频率分析以及内禀反应坐标(IRC)计算证实了过渡态和中间体的合理性.结果表明:Pt_(18)团簇催化肉桂醛选择性加氢反应有6条不同的反应路径,其中,C=O键加氢产物的最低活化能为98.42 k J/mol;C=C键加氢产物的最低活化能为122.88 k J/mol.综合分析发现Pt_(18)团簇催化肉桂醛选择性加氢反应中C=O键加氢所需的活化能最低.

The reaction mechanism on cinnamic aldehyde selective hydrogenation reaction catalyzed by Pt（18） cluster was studied by the density functional theory（ DFT）. The geometries and the frequencies of reactants,intermediates,transition states and products have been calculated at the B3 LYP/6-31 ＋ G（ d,p） level. Transition states have been confirmed by the corresponding vibration analysis and intrinsic reactions coordinate（ IRC）. The results showed that there were six different reaction paths in cinnamic aldehyde selective hydrogenation reaction catalyzed by Pt（18） cluster. The activation energies of rate-determining steps in which cinnamic aldehyde selective hydrogenation reaction catalyzed by Pt（18） cluster to form C =O adduct was 98. 42 k J/mol,and C =C adduct was 122. 88 k J/mol. The final result of the theory study showed that the activation energies of C =O adduct was lower in cinnamic aldehyde selective hydrogenation reaction catalyzed by Pt（18） cluster.