Catalytic Combustion of Soot over the Highly Active (La_0.9K_0.1CoO₃)_x/nmCeO₂ Catalysts

The highly active (La 0.9 K 0.1 CoO 3 ) x /nmCeO 2 catalysts consisting of comparably sized La 0.9 K 0.1 CoO 3 active component and CeO 2 support nanoparticle were studied on the catalytic combustion of soot by temperature-programmed oxidation (TPO) technique. The properties of oxygen species and the redox performances of catalysts were investigated by the method of O 2 -TPD and H 2 -TPR. During TPO process, all supported oxide catalysts showed lower T m than the corresponding nanometer CeO 2 support or pure La 0.9 K 0.1 CoO 3 perovskite. The best catalytic activity was obtained over (La 0.9 K 0.1 CoO 3 ) 20 /nmCeO 2 catalyst ( T m = 354 °C), and its catalytic activity for the combustion of soot is as good as supported Pt catalysts. During the catalytic combustion of soot, the surface α oxygen species should play an important role. The formation of surface oxygen-containing complexes (SOC) may be one of the key intermediate species according to the results of in situ DRIFT, and NO 2 released by surface nitrate species remarkably promote the soot oxidation.