Catalytic combustion of soot particulates over La2-xKxNiMnO6 catalysts

Abstract Nanosized La 2- x K x NiMnO 6 catalysts with ABO 3 type perovskite-like structure were prepared by auto-combustion method using citric acid as a ligand to control particle size and morphology. The structures and properties of these perovskite-like oxides were investigated by X-ray powder diffraction (XRD) and temperature-programmed reduction (TPR). The catalytic activities for soot combustion were evaluated by temperature-programmed oxidation (TPO) with pure O 2 and O 2 /NO x as oxidant, respectively. In the La 2- x K x NiMnO 6 catalysts, the partial substitution of K at A-site leads to an increase of the concentrations of high valence cation and oxygen vacancy, which enhance the catalytic activity for soot combustion. The optimal substitution amount of K was equal to x = 0.4 among these samples. T p (peak temperature) in O 2 -TPO profile was 420 °C and T p in O 2 /NO x -TPO profile was 370 °C over La 1.6 K 0.4 NiMnO 6 catalyst for soot particulates combustion under loose contact conditions between catalyst and soot.