Nitrate storage behavior of Ba/MnOx-CeO2 catalyst and its activity for soot oxidation with heat transfer limitations

A BaMnCe ternary catalyst was prepared by impregnating barium acetate on MnOx-CeO2 mixed oxides, with the monoxide supported catalysts and the solid solution support as references. The activities of the catalysts for soot oxidation were evaluated in the presence of NO under an energy transference controlled regime. BaMnCe presented the lowest maximal soot oxidation rate temperature at 393 degrees C among the catalysts investigated. Although BaMnCe experienced a loss in the specific surface area and low-temperature redox property due to blocking of the support pores by barium carbonate, its superior soot oxidation activity highlighted the importance of relatively stable bidentate/monodentate nitrates coordinated to Mnx+ and Cex+ sites and more stable ionic barium nitrate. About half of the nitrates stored on this catalyst decomposed within the temperature interval of 350-450 degrees C, and the ignition temperature of soot decreased significantly with involvement of the nitrates or NO2 released. (C) 2010 Elsevier B.V. All rights reserved.