Hydrogenation of o-Cresol at the Water/Pt(111) Interface

Catalytic experiments were performed to investigate the hydrogenation of o-cresol to 2-methylcyclohexanol on a platinum catalyst in water. It has been observed experimentally both here and in prior studies that intermediate ketones desorb from the catalyst surface in the vapor phase or in hydrocarbon solvents, but they are not observed when reactions are carried out in the aqueous phase. Density functional theory was employed to explore the atomic-scale mechanism of o-cresol hydrogenation at the water/Pt(111) interface. Here, we show that water plays a dual role of accelerating the rate of hydrogenation of these ketones by shuttling hydrogen from the surface while also decreasing the rate of desorption of the less polar ketone intermediate from the catalyst surface. These two effects, when combined, explain the lack of observation of these ketone intermediates when this hydrogenation reaction is carried out in the aqueous phase.