Reaction of ethane with deuterium over platinum(111) single-crystal surfaces

ABSTRAcrDeuterium exchange and hydrogenolysis of ethane were studied over LBL-17764 (111) platinum surfaces under atmospheric pressures and a temperature range of 475-625K.Activation energies of 19 Kcal/mole for exchange and 34 Kcal/mole for hydrogenolysis were obtained.The exchange reaction rates displayed kinetic orders with respect to deuterium and ethane partial pressures of -0.55 and 1.2, respectively.The exchange product distribution was U-shaped, peaking at one and six deuterium atans per ethane molecule, similar to results reported for other forms of platinum, e.g., supported, films, and foils.The presence of ethylidyne moieties on the surface was inferred from low energy electron diffraction and thermal desorption spectroscopy.A mechanism is proposed to explain the experimental results, in which ethylidyne constitutes an intermediate in one of two competitive pathways.