Synergy of NTP-La1-xAgxMn1-yCoyO3-δ Hybrid for Soot Catalytic Combustion at Low Temperature

Ag and Co co-doped La1-xAgxMn1-yCoyO3-δ perovskites were prepared by the citric acid sol–gel method. The maximum solubility of Ag+ in LaMnO3 decreased with the increase of Co doped in B-site, which lead to the exsolution of excess Ag+ from A-site of perovskite. The exsolution progress is more favorable to the formation of uniform and stable Ag nanoparticles on the perovskite substrate. The non-thermal plasma (NTP) assisted La1-xAgxMn1-yCoyO3-δ for soot catalytic combustion had been investigated under diesel exhaust gas conditions. When La1-xAgxMn1-yCoyO3-δ was utilized as the catalyst without NTP, the soot could hardly be oxidized at 200 °C. However, when La1-xAgxMn1-yCoyO3-δ was combined with NTP, the efficiency of soot removal was dramatically improved. The NTP-La0.5Ag0.5Mn0.8Co0.2O3-δ hybrid had the highest soot removal efficiency and CO2 selectivity. The combination of NTP and La1-xAgxMn1-yCoyO3-δ could form a synergistic catalytic effect, which significantly promoted the combustion of soot at low temperature. The results of characterization and experiments indicated that the synergistic catalytic performance depended on the coordination of short-living species in plasma, adsorbed oxygen and Ag nanoparticles on surface of La1-xAgxMn1-yCoyO3-δ. Based on these results, the reaction mechanism of plasma-catalyst hybrid for soot catalytic combustion was proposed.