Investigations Of Catalytic Performances Over Co₃O₄Catalyst

Owing to possession of Co (Ⅱ) and Co (Ⅲ) as well as unfull-filled d orbital of Co ions, Co3O4with spinel structure has attracted more and more attentions because of its high catalytic activity for CO low-temperature catalytic oxidation. In the case, the catalysts of Co3O4were prepared using the method of coprecipitation, which were pretreated in N2atmosphere at different temperatures. At the same time, their activities for CO low temperature oxidation were tested and the surface species of catalysts and their adsorption performance were characterized with TQ IR, O2-TPD and CO-TPD. The results show that pretreatment of catalysts in N2not only cleans the adsorbed water and carbonate species on the surface of the catalysts, but also promotes removal of surface oxygen species to form Co(Ⅱ) and oxygen vacancies. The optimal performance of Co3O4pretreated at400℃might be accounted for by the high content of oxygen species desorbed at low temperature as well as the low content of carbonate species decomposed at high temperature.The introduction of ZrO2/CeO2using the methods of impregnation and co-precipitation further promotes the activity of catalyst. The addition of promoters not only disperses Co3O4, increases the BET surface areas of catalysts, makes more active sites exposed, but also reinforces the interaction between the promoters and Co3O4, which is beneficial to species spillover between promoters and Co3O4, and then promotes the catalytic activity. The performances of Co3O4impregnated with0%,3%,6%and10%show that the one with6%of CeO2shows optimal catalytic activity. Furthermore, Co3O4-CeO2with co-precipitation displays the higher catalytic activity because of stronger interaction between Co3O4and CeO2. The promoter of ZrO2reveals the similar effect to Co3O4structure with CeO2, but promotes the catalytic activity in lower degree relative to CeO2because of lower oxygen storage ability;.