Spectroscopic study of the properties of surface compounds in methanol conversions on Cu/γ-Al2O3

Abstract

The reactions of methanol on the (10% Cu)/γ-Al2O3 surface were studied by the spectrokinetic method (simultaneous measurements of the conversion rates of surface compounds and the product formation rates). Bridging and linear methoxy groups result from the interaction of methanol with surface hydroxyl groups. Formate and aldehyde-like complexes form by the oxidative conversion of the linear methoxy groups. Hydrogen forms via the recombination of hydrogen atoms on copper clusters, and the hydrogen atoms result from interconversions of surface compounds. The source of CO2 in the gas phase is the formate complex, and the source of CO is the aldehyde complex. In the absence of methanol in the gas phase, dimethyl ether forms by the interaction between two bridging methoxy groups. When present in the gas phase, methanol reacts with methoxy groups on the surface. The roles of oxygen and water vapor in the conversions of surface compounds are discussed.