DRIFTS study of selective CO oxidation over Au/γAl2O3 catalyst
In this work, the surface species and possible mechanism of selective CO oxidation over Au/Al2O3 were studied using DRIFTS method. The species observed on the surface suggested that the reaction starts with the reaction of Au0/Au+OH with CO forming COAu0/Au+OH. This complex then reacts with O2-forming bicarbonate structure followed by formation of the second CO2 and recovery of Au0/Au+OH. It was also observed that CO2 in the feed increases the formation of carbonates or carboxylates, thus reducing CO oxidation. The presence of hydrogen, on the other hand, enhances the CO oxidation due to either by direct involvement in the mechanism, or by suppressing the formation carbonate like species and preventing the deactivation of catalyst.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Gold was mostly in metallic state with some contribution of Au+ 1 and Au+ 3. ► Carbonates, bicarbonates, hydroxycarbonyl and OH groups were observed on the surface. ► CO2 increased the formation of surface species while H2 decreased. ► The mechanism seems to proceed through the reaction of CO with AuOH complex.
Journal: Catalysis Communications - Volume 29, 5 December 2012, Pages 6–10