Highly selective α-Mn2O3 catalyst for cGPF soot oxidation: Surface activated oxygen enhancement via selective dissolution

The α-Mn2O3 catalyst was synthesized using selective dissolution method (SD) for soot oxidation on catalyzed gasoline particulate filter. The catalyst exhibited better soot oxidation activity and significantly higher CO2 selectivity than the samples prepared by traditional sol–gel or direct calcination method. The SD-treated catalyst not only presented sponge-like morphology with disorder-interconnected mesopores (∼15 nm) for facile CO diffusion and adsorption, but also displayed abundant oxygen adsorbed on vacancy sites (α-O) and oxygen of surface lattice (α′-O) for both soot and CO oxidation. These factors rather than Mn valence determine the higher amount of active surface oxygen, which results in better redox properties and soot oxidation activity. Besides, surface-oxygen complexes on soot contained surface functional groups (lactone, carboxylic and anhydride etc.). Therefore, both better CO oxidation ability and more surface functional groups led to excellent CO2 selectivity.