The selective hydrogenation reaction mechanisms (C=O addition mechanism

C=C 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 C=O addition mechanism to generate cinnamyl alcohol(COL) followed by further hydrogenation to saturated alcohols

of which the total hydrogenation process is almost endothermic.