279482 A Combined Experimental and Theoretical Study On CO Oxidation Mechanism Over Au38-Derived Au/TiO2 Catalyst
Two decades after supported Au clusters were first reported to be active for CO oxidation at low temperatures, the activity of these catalysts is still under investigation. These catalysts have been studied on a variety of metal oxide supports like CeO2, TiO2, ZrO2, Al2O3, Fe2O3, Co3O4, and SiO2. However, the most commonly studied catalyst for CO oxidation remains Au supported on TiO2 due to its higher activity.
Au38 clusters were synthesized using our previously reported method and impregnated on a mesoporous TiO2 support to give Au38/TiO2 catalyst. This catalyst was treated to remove the thiol ligands which were present as a result of thiol etching protocol used to synthesize the clusters. Three kinds of experiments were performed on the Au/TiO2 catalyst in a plug-flow fixed-bed reactor and an in situ DRIFTS cell at room temperature: a) CO flow for 5 min. followed by He flushing for 10 min, b) CO oxidation with 16O2 for 60 min., and c) CO oxidation with 18O2 for 60 min. These experiments suggest that the oxidation of CO occurs via a Mars van Krevelen of redox mechanism.