Hydrogenation of Ethylene over Platinum (111) Single-Crystal Surfaces

Article abstract of DOI:10.1021/ja00320a013

The hydrogenation of ethylene with both hydrogen and deuterium was studied(111) platinum single-crystal surfaces under a total pressure of 110 torr and a temperature range of 300-370 K.An activation energy (E_a) of 10.8 +/- 0.1 kcal/mol and kinetic orders with respect to hydrogen and ethylene partial pressure of 1.31 +/- 0.05 and -0.60 +/- 0.05, respectively, were observed.The deuterium atom distribution in the product from the reaction with D2 peaks at 1-2 deuterium atoms per ethane molecule produced, similar to what has been reported for supported catalysts.The reaction takes place on a partially ordered carbon covered surface, where the carbonaceous deposits have a morphology similar to that of ethylidyne.However, this ethylidine does not directly participate in the hydrogenation of ethylene, since both its hydrogenation and its deuterium exchange are much slower than the ethane production.A mechanism is proposed to explain the experimental results.