Oxidative dehydrogenation of alcohols on gold: An experimental and computational study on the role of water and the alcohol chain length

The oxidative dehydrogenation of primary alcohols promoted by gold nanoparticles was investigated from an experimental and computational viewpoint to derive a plausible reaction mechanism and to understand the role of water and alcohol chain length in the elementary steps. The influence of water in reaction kinetics and product distribution was determined in a laboratory-scale microreactor adding water to the reaction mixture in different amounts. DFT calculations revealed that the presence of water on the catalyst surface is beneficial to assist the key step in alcohol oxidation i.e., oxygen activation by protonation. The calculations were performed for primary alcohols ranging from methanol to butanol to understand the role of the alkyl chain length on the catalytic activity and to clarify experimental observations. General conclusions were drawn on the influence of temperature on product distribution when employing a typical support material for gold nanoparticles, Al₂O_3. The combination of experiments and theory has been useful to improve the knowledge of alcohol oxidation promoted by gold.