The influence of surface oxygen and hydroxyl groups on the dehydrogenation of ethylene on PdAu surface alloys. A theoretical cluster model study

The dehydrogenation of ethylene on Pd second-neighbor ensembles of both PdAu(1 0 0) and PdAu(1 1 1) surface alloys in presence of surface oxygen atoms (Os) and hydroxyl groups (OHs) was investigated at the density functional level with a cluster model approach. The calculated activation barriers for ethylene dehydrogenation to form vinyl on Os- and OHs-covered PdAu surfaces are significantly lower than those on clean surface alloys. Therefore, our outcomes suggest that a Langmuir–Hinshelwood-type mechanism involving a vinyl surface species cannot be excluded a priori when investigating the microscopic behaviour of the oxygen-assisted acetoxylation of ethylene on PdAu catalysts.