E. Abi-Aad, S. Capelle, A. Aboukais

Laboratoire de Catalyse et Environnement, Universite du Littoral-C6te d Opale, MREID, 145, route du Pertuis d Amont, 59140 Dunkerque, France 

The combustion of diesel soot has been studied in presence of copper-cerium oxide catalysts. These catalysts were prepared by impregnation of copper nitrate on ceria and calcination under air up to 1073 K. The solids were widely characterised by electron paramagnetic resonance (EPR) technique. For an atomic ratio Cu/Ce=l and a calcination temperature of 673 K, the catalyst seems to be t e most active in the combustion of diesel soot, when compared to other catalysts. The Cu monomers are more concerned than the dimers in this combustion. 

Cerium oxide based catalysts have been widely studied during the last two decades. Main catalytic application was the elimination of automotive exhaust emissions (1,2). The catalytic properties of this oxide has often been related with the mobility of oxygen vacancies in the solid (3,4) and hence with its capacity to release stored oxygen under reducing conditions tests (5,6).Moreover, A.F. Ahlstrom and C.U.I. Odenbrand (7) reported the deactivation by sulphur dioxide of supported copper oxide during the oxidation of soot. 

The purpose of this work is to study the catalytic properties of different copper-cerium oxides in the combustion of diesel soot and to correlate their activities with the nature of copper species present in the catalyst. 

Samples of Cu-Ce oxides are prepared by incipient wetness impregnation method. Cerium hydroxide is precipitated by adding cerium nitrate to a concentrated solution of NaOH. The precipitate is thoroughly washed with warm water, filtered and dried at 373 K before its calcination at 673 K for 6 hours in a flow of dry air. Copper nitrate of different amounts is then impregnated, at room temperature, on the oxide support. The samples are dried at 373 K and calcined at 673, 873 or 1073 K for 6 hours in a flow of dry air. Samples are denoted by lCuxCe673, lCuxCe873 and lCuxCel073 where x indicates the atomic ratio of cerium to copper in the solid, and the last number indicates the calcination temperature value of the sample. 

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