The oxidation of ethanol on Cu(110) and Ag(110) catalysts

The oxidation of ethanol was studied on Cu(110) and Ag(110) single crystals by temperature programmed reaction spectroscopy. The single crystal surfaces were preoxidized with 18O2, and deuterated ethanol, CH3CH2OD, was used to distinguish the hydroxyl hydrogen from the ethyl hydrogens. The ability of both surfaces to dissociatively chemisorb ethanol was greatly enhanced by surface oxygen. CH3CH2OD was selectively oxidized upon adsorption at 180 K to adsorbed CH3CH2O and D218O. The Ag(110) surface was more active than the Cu(110) surface for the dehydrogenation of ethoxide to acetaldehyde and hydrogen. The recombination of surface hydrogen with ethoxide to yield CH3CH2OH was also observed. Following high exposures of ethanol the surface intermediate CH3CH2OD2 was produced upon adsorption at 180 K from the interaction of two CH3CH2OD molecules, and this surface complex subsequently decomposed to C2H4, D2O and hydrogen. The present results for the oxidation of ethanol are compared to the previous investigations of methanol oxidation on Cu(110) and Ag(110).