(671e) Selective Hydrogenation of Crotonaldehyde over a Pdsn Catalyst: A First-Principles Study

It remains a challenge to design a catalyst for selective hydrogenation of α, β-unsaturated aldehydes. It is desirable to develop a catalyst that can selectively hydrogenate the carbonyl group and prevent full hydrogenation. Here, we report density function theory (DFT) calculations and detailed kinetic analysis, through which we investigate the hydrogenation reaction of crotonaldehyde on a PdSn surface. We find that the rate of the reaction is determined by dissociation of hydrogen molecules because of its high activation barrier. Meanwhile, the selectively of the hydrogenation products is controlled by the apparent barriers along different reaction pathways - hydrogenation of the C=C and C=O double bonds. We show that hydrogenation of the C=O bond of crotonaldehyde has a lower overall barrier, which leads to kinetically favorable production of the unsaturated alcohol. In addition, further hydrogenation of the unsaturated alcohol is halted because of the higher activation barrier as compared to its desorption from the surface. This work thus provides insights for developing an efficient catalyst for selective hydrogenation.