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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 temperatureprogrammed 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 R 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.

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