Efficient Catalysts of K and Ce Co-Doped LaMnO(3) for NO(x)–Soot Simultaneous Removal and Reaction Kinetics

[Image: see text] Presently, the treatment of four-way catalysts is important for reducing pollutant emissions from diesel engine exhaust, which is a major cause of urban haze. In this study, we prepared perovskite-type catalysts via the citric acid sol–gel method. Experiment results showed that K substitution at site A in LaMnO(3) decreased the agglomeration of the catalysts effectively, increased the contact with the reaction gas, promoted the conversion of Mn(3+) → Mn(4+), and reduced the ignition temperature of soot. Ce substitution at the B-site in La(0.5)K(0.5)MnO(3) produced a CeO(2) phase and decreased the Mn(4+)/Mn(3+) ratio to 0.49, which is conducive to improving the catalytic oxidation performance. The K and Ce co-doping had the best activation effect, which showed a low activation energy (10.87 KJ mol(–1)) and a high simultaneous removal rate of NO(x) (reaching 90% at 275 °C) and soot ignition at 250 °C under lean conditions.