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

摘要

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 T_(100) 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.