Abstract: A series of La-Co-Ce-O mixed oxide catalysts with different bulk compositions were synthesized using a citric acid complexation-organic template decomposition method. The samples have high specific surface area (above 100 m2/g), very uniform pore diameter (3.7～3.9 nm), and good thermal stability. The dispersion of CeO2 and Co3O4 crystallites in the samples prepared by the organic template decomposition is much higher than that by the conventional coprecipitation method. The samples prepared using this new method display much a higher activity for CO and propane oxidation than that by coprecipitation. The catalytic oxidation activity of the catalysts is not proportional to the number of the surface cobalt atoms, but is closely related to the synergism between the surface cobalt and cerium species. The catalytic synergetic effect is exhibited when the surface cobalt and cerium are in an atomic ratio nearly to one.

Key words: lanthanum, cobalt, cerium, mixed oxide, cetyltrimethylammonium bromide, mesoporous structure, carbon monoxide, propane, oxidation