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Diesel engines are very popular in European passenger cars and their technology has been developed to have cleaner raw emissions and lower fuel consumption. Therefore the exhaust temperatures are extremely low in urban driving conditions. The current diesel European driving cycle (EDC) and diesel catalyst ageing in different positions (Preturbo, CC and UF) were simulated successfully according to diesel light-duty exhaust gas conditions with laboratory equipment. A small mixer type EcoXcell structure was used in Preturbo position with high Pt loading to enhance in particular CO and hydrocarbon oxidations. The small metal substrated pre and larger main catalyst with active, zeolite containing washcoat were developed to decrease emissions. Both experimental and calculation simulations gave a prediction for grams per kilometer emissions for a single or combined catalyst system. The reaction and ageing rate based design can be used to optimize the diesel aftertreatment system.

The development of efficient, durable three-way catalysts with OBD facilities needs cooperation between different areas related to engine, control and catalyst technologies. High-loading Pd and Pd-Rh precatalysts with λ sensors upstream and downstream were evaluated in FTP cycle to find out the appropriate driving conditions for OBD-II. Diagnostic values were calculated by the damping of λ responses caused by the aged precatalyst. The ratio of oxygen storage capacity (OSC) and precious metals were studied to improve the correlation between calculated diagnostic values and the catalyst efficiency. In fact, the correlation from diagnostic values was better to NOx than to THC efficiency by bag 1 and 2 emissions in FTP 75. The amplitude method with two λ sensors over warm converters is commonly used for OBD but hydrocarbon emissions are mainly formed during cold-start periods. Therefore the OBD calibration and catalyst optimal compositions have conflicting demands.

Our major challenge for future catalyst systems was to develop more thermally stable washcoats for close coupled operating conditions and for engines operating under high speed and load conditions. To design these future emission systems extensive research and development was undertaken to develop methods to disperse and stabilize the key catalytic materials for operation at much higher temperatures. Our second priority was to design catalysts that are more effective under low exhaust temperature exhaust conditions and have improved oxygen storage properties in the washcoats. Incorporating new materials and modified preparation technology a new generation of metallic catalyst formulations emerged, those being trimetallic K6 (Pt:Pd:Rh and bimetallic K7 (Pd+Pd:Rh). Our target was to combine the best property of Pt:Rh (good NOx reduction) with that of the good HC oxidation activity of Pd and to ensure that precious metal/support interactions were positively maintained.