Influence Li2O-Doping on Oxide Surface and Catalytic Properties of CuO/Co3O4 Solids

Abstract

The effect of Li₂O-doping on solid-solid interaction, surface and catalytic properties of CuO - Co₃O₄ were investigated using XRD, nitrogen adsorption at -196^oC and catalytic oxidation of CO by O₂ at 150-250^oC. The nominal composition of the system was 0.2CuO/Co₃O₄ and the amount of dopant was varied between 0.75 and 3 mol% Li₂O. The results obtained revealed that Li₂O-doping inhibited the solid-solid interactions between the mixed oxides precalcined in air at 600^oC and decreased the degree of crystallinity and particle size of Co₃O₄ phase. This treatment led also to a decrease in the specific surface areas of the doped adsorbents precalcined at different temperatures. The catalytic activities towards CO-oxidation by O₂ of pure solids decreased progressively by increasing the precalcination temperatures in the range 400-600^oC. The doping process brought about a significant increase in the catalytic activities. Lithia doping of the investigated system did not modify the mechanism of the catalytic reaction but changed the concentration of the catalytically active centers without changing their energetic nature.