Rapporteur M. Ph. Vernoux Directeur De Recherchè a L'ircelyon Rapporteur

This study describes the development of kinetic models for platinum-ceria-zirconia (Pt/CexZr1−xO2)-catalysed diesel particle filter (DPF) regeneration. Such models have a practical purpose in that they can be used to calculate source terms in 3D flow models, and they also have an intrinsic interest for the understanding of the mechanisms of catalysed soot oxidation. The core of this kinetic analysis consists in estimating Arrhenius parameters of a number of (semi) detailed reaction steps by fitting calculated curves to experimental ones. In doing so, understanding of the roles of the different reactants has been gained, and the efficacy and limitations of the modelling procedure for gas-solid heterogeneous reactions investigated. Amongst the examined aspects is the feasibility of attributing physically meaningful values to individual parameters in large reaction mechanisms. This is achieved by fitting one “subset”of reaction steps at a time. The procedure is illustrated by means of the cases of soot oxidation by NO, NO2 and/or O2, NO oxidation catalysed by ceriabased catalysts and soot oxidation catalysed by Pt/CexZr1−xO2. Experiments used for these kinetic studies are temperature programmed tests in a fixed bed reactor. In order to extract kinetic parameters, a reactor model describing gas flow through a bed of particles and a meanfield model of soot and catalyst surface chemistry have been developed. The interest of these detailed kinetic mechanisms lies in their ability to describe all the reaction products instead of concentrating merely on global soot consumption rate. The role of a heterogeneous reactive surface, such as that of soot structure and ceria-zirconia composition/structure have been considered, as well as the soot/catalyst ratio.