Activity of 5% CuO/Ce_{1 – x}Pr_xO_y Catalysts in the Reaction of Carbon Monoxide Oxidation with Oxygen in an Excess of Hydrogen¹

Abstract—The 5% CuO/Ce_{1 – x}Pr_xO_y catalysts were synthesized on the basis of CeO₂ and PrO₂ oxides and Ce_1 – xPr_xO_y solid solutions with x = 0.2, 0.5, and 0.8. Highly dispersed copper oxide was present in the 5%CuO/Ce_1 – xPr_xO_y catalysts. Upon interaction with the support, it formed active oxygen, which participated in CO chemisorption and a low-temperature reaction of CO oxidation in the presence of hydrogen. The highest conversion of CO in an excess of H₂ (γ_mах(Т)), which was close to 100%, was obtained at temperatures of 120–160°C on a 5% CuO/CeO₂ catalyst. Upon the modification of CeO₂ with Pr cations, 5% Ce_0.2Pr_0.8O_y sample, it decreased to 65% at 220°C due to an increase in the bond strength of oxygen in copper-containing centers. A maximum conversion of CO (93%) on a sample of 5% CuO/PrO_y was detected at 200°C. Upon the modification of PrO₂ with Ce cations, the activity of 5% CuO/Ce_0.5Pr_0.5O_y and 5% CuO/Ce_0.2Pr_0.8O_y catalysts did not exceed that of 5% CuO/PrO_y. The forms of CO and CO₂ adsorption on 5% CuO/Ce_{1 – x}Pr_xO_y samples were studied using the TPD method. In a range of 170–500°C, the desorption of oxygen from the supports of 5% CuO/Ce_0.5Pr_0.5O_y and 5% CuO/PrO_y samples was observed. The occurrence of the reaction on 5% CuO/Ce_{1 – x}Pr_xO_y catalysts was discussed. With consideration for the properties of CO complexes formed on copper-containing oxidation and adsorption centers, their participation in the reaction of low-temperature oxidation in hydrogen was examined.