Highly Active La_(1-x)K_xCoO3 Perovskite-type Complex Oxide Catalysts for the Simultaneous Removal of Diesel Soot and Nitrogen Oxides Under Loose Contact Conditions

摘要

The nanometric La_(1-x)K_xCoO3 (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 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)CoO3 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)CoO3 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.