VOC oxidation over MnOx–CeO2 catalysts prepared by a combustion method

MnOx–CeO2 catalysts were prepared by a urea combustion method and their performance in the oxidation of ethanol, ethyl acetate and toluene was evaluated. XRD, XPS, H2-TPR and N2 physisorption were employed in catalyst characterization. Mn2+ and Mn3+ ions are present in the catalysts. In ceria-rich materials, crystalline manganese oxide phases are absent and Mn ions are homogeneously distributed between the bulk and the surface suggesting incorporation of Mn ions in ceria structure. In Mn-rich materials, segregation of a Mn3O4 phase takes place. The mixed oxides get reduced by H2 at lower temperatures than the corresponding single oxides and Mn ions promote reduction of ceria. The surface area of MnOx–CeO2 catalysts is larger than the one of single oxides prepared with the same method. The larger surface area of MnOx–CeO2 catalysts counterbalances their smaller specific activity allowing complete conversion of the examined VOCs at lower temperatures compared to the single oxides.