Highly active La1-xKxCoO3 perovskite-type complex oxide catalysts for the simultaneous removal of diesel soot and nitrogen oxides under loose contact conditions

The nanometric La(1-x) K(x) CoO(3) (x = 0-0.30) perovskite-type oxides were prepared by a citric acid-ligated method. The catalysts were characterized by means of XRD, IR, BET, XPS and SEM. The catalytic activity for the simultaneous removal of soot and nitrogen oxides was evaluated by a technique of the temperature-programmed oxidation reaction. In the LaCoO(3) catalyst, the partial substitution of La(3+) at A-site by alkali metal K(+) enhanced the catalytic activity for the oxidation of soot particle and reduction of NO(X). The La(0.70)K(0.30)CoO(3) oxides are good candidate catalysts for the simultaneous removal of soot particle and NO(X). The combustion temperatures for soot particles over the La(0.70)K(0.30)CoO(3) catalyst are in the range from 289 to 461 C, the selectivity of CO(2) is 98.4% and the conversion of NO to N(2) is 34.6% under loose contact conditions. The possible reasons that can lead to the activity enhancement for the K-substitution samples compared to the unsubstituted sample (LaCoO(3)) were given. The particle size has a large effect on its catalytic performance for the simultaneous removal of diesel soot and nitrogen oxides.