Reaction Mechanism Study of the Di-Air System and Selectivity and Reactivity of NO Reduction in Excess O₂

We studied the mechanism of NO reduction as well as its selectivity and reactivity in the presence of excess O₂. Results show that fuel injection and/or pretreatment are important for ceria catalyst reduction and carbon deposition on the catalyst surface. Oxygen defects of reduced ceria are the key sites for the reduction of NO into N₂. The deposited carbon acts as a buffer reductant, i.e., the oxidation of carbon by lattice oxygen recreates oxygen defects to extend the NO reduction time interval. A small amount of NO showed a full conversion into only N₂ both on the reduced Zr-La doped ceria and reduced Pt-Zr-La doped ceria. Only when the catalyst is oxidised NO is converted into NO₂.