肉桂醛在M13（M=Au，Pt）团簇表面加氢反应机理分析

摘要

The selective hydrogenation reaction mechanisms (CO addition mechanism, CC addition mechanism, and 1,4-conjugate addition mechanism) of cinnamaldehyde over M13(M=Au, Pt) were investigated using density functional theory. The transition states of each elementary reaction step in selective hydrogenation of cinnamaldehyde were explored by the complete LST/QST method on the basis of optimized stable adsorption configurations, hence the activation energy and reaction heat were obtained. The calculation results showed that on Au13 cluster, cinnamaldehyde most likely follows 1,4-conjugate addition mechanism to produce very unstable ENOL, and tautomerizes to benzenepropanal(HCAL), of which the total hydrogenation process is almost exothermic. However, on Pt13 cluster, it most likely follows the CO addition mechanism to generate cinnamyl alcohol(COL) followed by further hydrogenation to saturated alcohols, of which the total hydrogenation process is almost endothermic.%采用密度泛函理论系统地研究了肉桂醛在正二十面体M13(M=Au, Pt)团簇上的选择性加氢反应机理(CO, CC以及1,4共轭加成机理)。在稳定吸附构型的基础上，通过Complete LST/QST方法探索肉桂醛选择性加氢反应中各基元反应的过渡态，得到各反应的活化能和反应热。计算结果表明：肉桂醛在Au13团簇最可能发生1,4共轭加成得到烯醇，但烯醇很不稳定，会发生异构生成苯丙醛，反应总体放出热量；肉桂醛在Pt13团簇最可能发生C O加成得到肉桂醇，肉桂醇进一步加氢得到饱和醇，反应总体吸收热量。