Abstract
The reactions of ethanol have been studied on bare and Au supported TiO2 polymorphs (anatase and rutile) in order to understand the effect of Au loading and prior O-2 treatment on the reaction selectivity and conversion using temperature programmed desorption (TPD). Although O-2 treatment has negligible effect on the reaction selectivity of ethanol on TiO2 alone it considerably affects the reaction on Au/TiO2.Au/TiO2 had three main effects on the reaction when compared to TiO2 alone. First, it switches the reaction selectivity of the dehydration (to ethylene) in favor of dehydrogenation (to acetaldehyde) on both polymorphs. Second, it decreases the desorption temperature of the main reaction products. Third, it increases secondary reaction products (mainly C-4 (crotonaldehyde, butene, furan) reaching ca. 78% of the overall carbon selectivity for the 8 wt.% Au/TiO2 anatase. These effects are more pronounced on the anatase phase when compared to that on the rutile phase. Reasons for these are discussed. (C) 2015 Elsevier B.V. All rights reserved.