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Catalyzed diesel particulate filter systems have now been successfully introduced and implemented in Europe. In the meantime, automotive manufacturers are working on the second generation of catalytic filters with the aim of reducing the overall system costs. In particular savings in precious metal costs are focussed by the use of highly-active catalysts which are stable at high temperatures. A possible approach here is the implementation of oxidation catalysts and catalytically coated filters based on platinum and palladium. In this context, the functio-nality of platinum/palladium-based, catalyzed filters was investigated by numerous measurements on a synthetic gas and an engine bench as well as by vehicle tests on a roller dynamometer. The HC/CO oxidation activity, the poisoning resistance towards sulfur and the desulfurization capability, the exothermic behaviour due to the conversion of subsequently injected hydrocarbons and the NO2 formation potential were examined in detail.

This paper describes a study of ternary V2O5/WO3/TiO2 SCR catalysts coated on standard Celcor® and new highly porous cordierite substrates. At temperatures below 275°C, where NOx conversion is kinetically limited, high catalyst loadings are required to achieve high conversion efficiencies. In principle there are two ways to achieve high catalyst loadings: 1. On standard Celcor® substrates the washcoat thickness can be increased. 2. With new highly porous substrates a high amount of washcoat can be deposited in the walls. Various catalyst loadings varying from 120g/l to 540 g/l were washcoated on both standard Celcor® and new high porosity cordierite substrates with standard coating techniques. Simulated laboratory testing of these samples showed that high catalyst loadings improved both low temperature conversion efficiency and high temperature ammonia storage capacity and consequently increased the overall conversion efficiency.