Kinetic and in situ DRIFT spectroscopy studies of NO oxidation, and reduction by C3H6 in excess O2 over γ-Al2O3 and Au/γ-Al2O3

The in situ DRIFT spectroscopy studies of NO and NO2 SCR were performed on gamma-Al2O3 and Au/gamma-Al2O3. The obtained results indicate that the initiation of NO SCR on Au/gamma-Al2O3 involves the oxidation of NO to NO2 at active centers at the interface between Au and Al2O3 followed by coupling of the NO2 or its adspecies, NOx-, with activated C3H6 on active sites on Al2O3 to form CnHmNxOy species, which are responsible for the propagation step. Its subsequent internal rearrangement and decomposition leads to the formation of N-2 and other products. Taken together, the obtained results suggest that the NO2 intermediacy benefits the NO SCR over gold catalysts as a reaction initiator or oxygen transfer agent.