Abstract: Co₃O₄, CeO₂ and Cobalt cerium mixed oxides catalysts were prepared by sol-gel method. The properties of the catalysts used for catalytic oxidation of p-cresol to achieve selectivity p-hydroxyben-zaldhyde were investigated. It's concluded that the activity and the selectivity of Cobalt cerium mixed oxide is the best. By using electron paramagentic resonance (EPR) method, the oxygen adsorbed or desorbed on three catalysts, and the action contacted with p-cresol in controlled-atmosphere have been investigated respectively. The EPR results confirm that a signal with 3-g values (2.003~2.048) comes from the species of surface adsorbing oxygen, and that they can be assigned to superoxide species O₂^- chemisorbed on the samples. The species O₂^- is the catalytic active one. Its concentration and complex state correlate with the catalytic oxidation activity and the selectivity of the catalysts.

Key words: Cobalt cerium mixed oxides, p-cresol, Catalytic oxidation, EPR, Adsorbed oxygen