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In order to achieve SULEV emission legislation the overall efficiency of the exhaust gas aftertreatment system has to be increased. Beside engine-out emissions and air/fuel ratio control especially during cold start and during transient driving conditions the catalyst has to be optimized regarding cold start and efficiency under warmed-up conditions. The paper will show emission test results of different catalyst designs (various cell-densities and foil thicknesses, cone-shape catalysts and electrically heated catalysts) measured on a dynamic engine test bench. With an optimized SULEV catalyst system emission tests in a close-coupled position of a mid-size passenger car will be presented.

For compliance with the future emission standards worldwide, modifications to the catalytic converter systems are necessary to increase efficiency. To improve the cold start behavior, which is of great significance in the overall effectiveness, the electrically heated catalyst is a proven tool. By using the Emitec Heated Catalyst (EMICAT), it is possible to show a long-term stable catalyst system with low power requirement with the help of specific physical data for foil catalysts. The influence of catalyst design, heating energy, cold start management and test cycle (FTP and European test cycle) will be discussed. Emission results of an aged electrically heated catalyst system and mechanical service life results will be demonstrated.