DFT Modeling of Mechanism of Hydrogenation of Phenylacetylene into Styrene on a Pd(111) Surface

A quantum chemical study of the possible routes of the phenylacetylene (PA) hydrogenation to styrene on a Pd(111) surface is carried out by the DFT-PBE method in the scalar-relativistic approximation. It is shown that the routes associated with the formation of the Ph–C–CH2 or Ph–CH–CH intermediates at the first stage have similar values of the turnover frequency (156 and 48 h–1, respectively). The route associated with the 1,2-hydride transfer in the adsorbed PA molecule is improbable due to the formation of a thermodynamically stable intermediate, Ph–CH–C. The interaction of the Ph group in the adsorbed PA molecule with the metal surface leads to the nonselective hydrogenation of the PA.