Promotion Effect of Ce Doping on Catalytic Performance of LaMnO3 for CO Oxidation

Abstract

In this paper, Ce-doped La1-xCexMnO3 perovskite catalysts are prepared by the sol–gel method, and the promotion effect of Ce doping on LaMnO3 catalysts for CO oxidation is investigated. The catalysts are characterized by X-ray diffractograms, Raman, N2 physisorption isotherms, temperature-programed reduction with H2, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show that the Ce doping greatly improves the catalytic activity of LaMnO3 for CO oxidation. Among the La1-xCexMnO3 catalysts, La0.8Ce0.2MnO3 shows the best CO catalytic activity, with 100% CO conversion obtained at 180 °C. The characteristic results show that the LaMnO3 perovskite phase exists in all Ce-doped catalysts, and the CeO2 crystalline phase begins to appear at x ≥ 0.1. The high activity of La0.8Ce0.2MnO3 for CO oxidation could be that: (1) it possesses large surface area (25.8 m2/g) to contact with reactants; (2) it has a high surface Ce3+/(Ce3+ + Ce4+) ratio of 0.27, which means high content of oxygen vacancies used for O2 adsorption and activation; and (3) it exhibits strong reducibility that is beneficial to CO activation.