Highly Active La1− x K x CoO3 Perovskite-type Complex Oxide Catalysts for the Simultaneous Removal of Diesel Soot and Nitrogen Oxides Under Loose Contact Conditions.

The nanometric La1− x K x CoO3 ( 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 LaCoO3 catalyst, the partial substitution of La3+ at A-site by alkali metal K+ enhanced the catalytic activity for the oxidation of soot particle and reduction of NO x . The La0.70K0.30CoO3 oxides are good candidate catalysts for the simultaneous removal of soot particle and NO x . The combustion temperatures for soot particles over the La0.70K0.30CoO3 catalyst are in the range from 289 to 461 °C, the selectivity of CO2 is 98.4% and the conversion of NO to N2 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 (LaCoO3) were given. The particle size has a large effect on its catalytic performance for the simultaneous removal of diesel soot and nitrogen oxides. [ABSTRACT FROM AUTHOR]