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Engine and laboratory tests were carried out to examine the performance of NOx adsorption catalysts for gasoline lean burn engines in fresh and aged condition. The results show that fresh NOx adsorption catalysts have the potential to meet EURO III emission standards. However, to accomplish these the fuel must contain a low sulfur concentration and the engine must be tuned to optimize the efficiency of the catalyst. After engine or furnace aging upto 750°C the catalyst shows some loss of NOx adsorption efficiency. This deterioration can be offset somewhat by increasing the frequency of lean/rich switching of the engine. Temperatures higher than 750°C may cause an irreversible destruction of the NOx, storage features while the three-way activity of the catalyst remains intact or even may improve. With reference to several physicochemical investigations it is believed that the detrimental effect of catalyst aging is attributed to two different deactivation modes.

The influence of different port designs on the generation of a swirl flow is described on the basis of stationary and non-stationary flow analyses. Subsequently, engine test bench analyses with a 3-valve one-cylinder engine were performed to assess the aforementioned port configurations with respect to their influence on the lean-burn behaviour. The most favourable port design was then used to analyse various combustion chamber shapes in order to further improve the engine behaviour during lean-burn operation and to select the most promising combustion chamber variant. Finally, the port and combustion chamber configurations thus identified were applied in vehicle simulation tests with lean-burn and EGR-burn operation to check the emission behaviour for compliance with the future European level 3 emission limits.