Influence of Washcoat Distribution on the Performance of Diesel Oxidation Catalysts

The assessment of tighter and tighter emission targets, and the increase of efficiency of Diesel engines is pushing towards the need of oxidation catalysts capable of high conversion performance at very low temperatures. These capabilities can be achieved only by the adoption of very high noble metal loadings (up to 140 g/ft³), which lead to very high costs. Washcoat distribution may play a key role in this context. In this paper the influence of washcoat distribution on light-off behaviour of a Diesel Oxidation Catalyst has been then investigated by means of a 3D numerical model. The model is capable of representing the coupling among flow, washcoat diffusion and detailed surface chemistry. Results state that the adoption of an optimized washcoat distribution may roughly lead to cost-savings of the order 30-40% in terms of noble metal loading.