Oxidation of Methanol on a PdO(101) Thin Film

Abstract

We investigated the oxidation of methanol on a PdO(101) thin film using temperature-programmed reaction spectroscopy (TPRS) and X-ray photoelectron spectroscopy (XPS). We find that the complete oxidation of methanol occurs almost exclusively on PdO(101) during TPRS experiments conducted at low initial methanol coverages. Partial dehydrogenation of the adsorbed methanol gives rise to a desorption-limited H2O peak at 335 K, while a reaction-limited process causes CO2 and H2O to desorb concurrently at 450 K. The desorption yield of CO2 increases as the methanol coverage rises to ∼0.12 ML (monolayer) but remains steady with increasing coverage thereafter. At high methanol coverage, we observe the desorption of methyl formate, formaldehyde, H2, and H2O in TPRS peaks between ∼285 and 305 K in addition to complete oxidation products. The yields of the partial oxidation products increase with increasing methanol coverage above ∼0.12 ML and start to plateau above a methanol coverage of about 0.5 ML. At saturation ...