Effect of pretreatment atmosphere on CO oxidation over α-Mn2O3 supported gold catalysts

The microstructural properties of Au/α-Mn2O3 catalysts moderately pretreated under different atmospheres, i.e., O2, He and H2, in relation to their activities and stabilities on CO oxidation were investigated. The highest initial activity was obtained for the He-pretreated catalyst, which, however, suffered the most severe deactivation with time on stream. Pretreatment with O2 resulted in the best stability and had the highest steady-state activity among the three catalysts. TEM results revealed that the pretreatment has a negligible effect on the gold particle size. While the formation of moderate surface oxygen vacancies before reaction was suggested to be responsible for the highest initial activity of He–Au/α-Mn2O3, overreduction of the oxide support could explain the inferior activity of the H2-pretreated catalyst. Based on the XPS and in situ DRIFTS studies, the superior performance of the O2-pretreated O2–Au/α-Mn2O3 catalyst can be attributed to the creation of a specific oxygen-enriched interface leading to an enhanced metal–support synergy.