Regeneration of Au/γ-Al2O3 deactivated by CO oxidation

Au/gamma-Al2O3 deactivates in CO oxidation, but it exhibits stable activity in selective CO oxidation (SCO) in the presence of H-2. The activity for CO oxidation could be suppressed significantly by thermal treatment at 100degreesC, and the lost activity could be recovered by exposing the catalyst to water vapor at room temperature. A catalyst deactivated in CO oxidation could be regenerated by exposing it to H-2 at room temperature or by running the SCO reaction over it. The results can be explained with a reaction mechanism for CO oxidation involving an active site that consists of an ensemble of metallic Au atoms and Au-hydroxyl. Deactivation in CO oxidation is due to the formation of an inactive carbonate, and deactivation by thermal treatment is due to dehydroxylation of the Au-hydroxyl.