Influence Li2O-Doping on Oxide Surface and Catalytic Properties of CuO/Co3O4 Solids
The effect of Li2O-doping on solid-solid interaction, surface and catalytic properties of CuO - Co3O4 were investigated using XRD, nitrogen adsorption at -196oC and catalytic oxidation of CO by O2 at 150-250oC. 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 600oC 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 400-600oC. 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.
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