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THE DEVELOPMENT of a novel precious metal catalyst system supported on a metal substrate is outlined. The key nature of the metallic species is demonstrated. A high performance alloy, FECRALLOY STEEL®, is identified as a suitable material. Conversion of this alloy into a durable catalyst using a proprietary pre-treatment to render it compatible with existing catalysts and production procedures is discussed. The flexibility in processing with respect to key design features e.g. cell density, is emphasised. The influence of support variables such as volume, cell density etc., on the performance of an oxidation catalyst is reported together with comparable data for ceramic supported catalyst. It is shown that at zero hours, equivalent performance, at no power loss penalty relative to ceramics, can be secured by judicious choice of cell density/volume combinations. Such equivalence can be achieved with significantly lower volumes and significant scope exists for further optimisation.

The low exhaust gas temperatures experienced on light duty Diesel vehicles present a very challenging environment for the successful operation of catalytic aftertreatment. To meet the future more severe legislation, Diesel engines are being developed with greater combustion efficiencies and advanced fueling control. These engine developments may produce lower particulate matter (PM) and nitrogen oxides (NOx) emissions, but increased hydrocarbon (HC) and carbon monoxide (CO) emissions may occur. As a result of these engine changes exhaust gas temperatures may reduce still further. These factors demand catalysts with high oxidation activity at low temperatures. This paper reviews oxidation catalyst technology developed for light duty Diesel vehicles and the factors affecting their performance. Results obtained on synthetic gas rigs, bench engines and vehicles are presented. A discussion oh the effect of the level of sulfur (S) present in Diesel fuel on aftertreatment is given.