Reactions of ethanol on Ru(0001)

The adsorption and reactions of ethanol on Ru(0001) were studied with temperature-programmed desorption (TPD) and reflection–absorption infrared spectroscopy (RAIRS). Ethanol was found to adsorb intact onto Ru(0001) below 100 K. From 175 K to 200 K, ethanol is converted into ethoxy groups, which undergo further dehydrogenation, leading to the formation of hydrogen, CO and surface carbon. The absence of aldehydes and methane as desorbing product molecules, as well as the intermediate species observed in the RAIRS spectra, show that the reaction proceeds via β-hydrogen abstraction of the ethoxy groups, resulting in an oxametallacycle reaction intermediate that undergoes decarbonylation to CO, C and hydrogen. The surface carbon, formed by the reaction, decreases the reactivity of the surface in subsequent reaction cycles. The amount of CO produced from a full monolayer of ethanol is limited to about 0.1 ML, because of the competition between ethanol dehydrogenation and desorption.