Catalytic oxidation of CO by O2 over nanosized CuO–ZnO system prepared under various conditions

Abstract

AbstractA series of copper and zinc mixed oxides composed of equimolar ratio and treated with 0.05 Al2O3/mol catalyst has been prepared by coprecipitation method using their nitrates in presence of 1 M NaOH solution. The precipitation was carried out at a pH 9.5 and 50°C. The results revealed that the bulk of various solids consisted of CuO and ZnO having ratios varying between 0.84 and 0.98. On the other hand, the values of surface concentrations of copper and zinc were bigger than those present in the bulk. The values of surface Cu/Zn ratio varied between 1.04 and 1.46 depending on the mode of preparation and calcination conditions. The mixed solids existed as nanocrystalline CuO and ZnO phases. The surface characteristics are strongly dependent on mode of coprecipitation and calcination temperature. The computed SBET values varied between 146 and 23 m2/g depending on mode of coprecipitation and calcination temperature. The increase of calcination temperature of different adsorbents within 300–400°C led to a significant progressive decrease in the BET‐surface area with subsequent increase in the values of mean pore radius. All adsorbents are mesoporous solids. All prepared solids showed a good catalytic activity in CO oxidation by O2, which proceeds via first order kinetics in all cases. The activation energy of the catalysed reaction was determined for various solids and the computed values were very small indicating the big catalytic activity of the investigated solids.