Study of ethanol reactions on H2 reduced Au/TiO2 anatase and rutile: effect of metal loading on reaction selectivity

Abstract

The effect of Au particle size and loading (over TiO2 anatase and rutile) on the reaction selectivity and conversion of ethanol has been studied using temperature programmed desorption. The addition of Au onto TiO2 had three main effects on the reaction. First, a gradual decrease is observed in the reaction selectivity of the dehydration (to ethylene) in favor of dehydrogenation (to acetaldehyde) with increasing Au loading on both polymorphs of TiO2. Second, a gradual decrease is seen in the desorption temperature of the main reaction products also with increasing Au loading. Third, secondary reaction products [mainly C4 (crotonaldehyde, butene, furan) and C6 (benzene) hydrocarbons] increased considerably with increasing Au loading reaching about 60% for benzene for the 8 wt-%Au/TiO2 anatase. An inverse relationship between the interface lengths of Au particles on TiO2 and desorption temperatures of reaction products is found.