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

Abstract

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.