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, H-2-TPR and N-2 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 H-2 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. (C) 2008 Elsevier B.V. All rights reserved.