Thermally stable ceria-zirconia catalysts for soot oxidation by O2

Ce-Zr mixed oxides calcined at 1000 degrees C are more active catalysts for soot oxidation than pure CeO2 calcined at the same temperature, both in loose and tight contact between soot and catalyst. 1000 degrees C sinterised-CeO2 presents a very low surface area (2 m(2)/g), a large crystal size (110 nm) and a lack of surface redox properties. Ce-Zr mixed oxides present higher BET surface areas (typically 17-19 m(2)/g), smaller crystal sizes and enhanced redox properties. The Zr molar fraction does not affect appreciably the catalytic activity of Ce-Zr mixed oxides in the range studied (Zr molar fraction from 0.11 to 0.5 1). (C) 2007 Elsevier B.V. All rights reserved.