Promotional role of ceria on cobaltosic oxide catalyst for low-temperature CO oxidation

Abstract

Ceria modified Co₃O₄ catalysts for low temperature CO oxidation were prepared by a precipitation–oxidation method, and characterized by low-temperature N₂ adsorption/desorption, TPR, O₂–TPD, CO–TPD and transient–response reaction. The roles of ceria in CeO₂–Co₃O₄ catalyst and the effect of pretreatment on the performance of CeO₂–Co₃O₄ for CO oxidation were investigated in detail. The results show that the presence of CeO₂ can increase its surface area, reduce the crystal size of Co₃O₄, and improve obviously the catalytic activity and stability of Co₃O₄ for CO oxidation, such as its T₁₀₀ is only −60 °C. It was also found that the addition of CeO₂ can not only promote the adsorption of O₂ and the reaction of adsorbed CO with surface oxygen species to form CO₂, but also increase the CO₂ desorption speed. The pretreatment method can affect the catalytic activity of CeO₂–Co₃O₄, the catalyst treated in N₂ exhibits higher catalytic activity for low-temperature CO oxidation due to formation of oxygen vacancy. The catalyst reduced in H₂ shows lower activity for CO oxidation although it has more surface oxygen vacancies, because of the difficult desorption of CO₂ on the reduced CeO₂–Co₃O₄ catalyst.