Anchoring on the surface and doping in the structure: The two forms of Ag existing in LaCoO3 perovskite for simultaneous catalytic oxidation and removal of various pollutants

To simplify the exhaust treatment process of diesel engine exhaust, the catalytic diesel particle filter (CDPF) was proposed to offer additional oxidation from the diesel oxidation catalyst (DOC). In this work, an oxidative perovskite based compound catalyst Ag8.0/LaAg2.0CoO3 doped with Ag+ in the structure and with Ag nanoparticles on the surface, was designed. Both CO and HC can be removed by catalytic oxidation, and the combustion temperature T50 of soot can also be lowered to 354℃ by adjusting the ratio of NO2/NOx. The characterization results and density functional theory calculations show that there is competitive adsorption between C3H6 and CO on the Ag nanoparticle. In addition, it is observed a strong metal-support interaction (SMSI) between the Ag nanoparticles and the Co atoms on the surface of perovskite support, boosting the catalytic activity of NO at low temperatures. We also found that the catalytic oxidation of soot follows the NO2 assisted oxidation mechanism.