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The regulations for mobile applications will become stricter in Euro 6 and further emission levels and require the use of active aftertreatment methods for NOX and particulate matter. SCR and LNT have been both used commercially for mobile NOX removal. An alternative system is based on the combination of these two technologies. Developments of catalysts and whole systems as well as final vehicle demonstrations are discussed in this study. The small and full-size catalyst development experiments resulted in PtRh/LNT with optimized noble metal loadings and Cu-SCR catalyst having a high durability and ammonia adsorption capacity. For this study, an aftertreatment system consisting of LNT plus exhaust bypass, passive SCR and engine independent reductant supply by on-board exhaust fuel reforming was developed and investigated. The concept definition considers NOX conversion, CO2 drawback and system complexity.

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.