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In recent years, automobile emission limits have been tightened world wide. PZEV (Partial Zero Emission Vehicle) which is the most stringent regulation has been imposed in California. To meet the strict PZEV regulation, automotive manufacturers are requesting the catalyst system to have quick light-off characteristics and excellent steady state performance with limited precious group metals (PGM) usage due to the strong price pressure. Moreover, the catalyst can not use high cell density substrate for increasing geometric surface area and reducing heat mass, since the backpressure of exhaust system must be decreased to improve the vehicle power for the PZEV application. This paper will present an efficient catalyst formulation that has been designed to maximize the performance with considerably reduce PGM loading. The catalyst washcoat has been optimized by improving the catalyst geometric surface area, gas diffusivity and thermal mass.

Global environmental consideration is now one of the essential components in automotive design. This concern needs be addressed not only by aftertreatment systems but also engine control technologies. In this paper, we will present an efficient emission control system that has been designed based upon the combination of advanced engine control and catalyst technologies. The system has successfully achieved the stringent US ULEV2 emission regulations and the vehicle installed with this system has been commercialized in the marketplace. In this system, the advanced fuel control system was able to facilitate quick light-off of the catalyst so that the cold start emission could be minimized. The engine A/F control is so precise that the catalyst can use the material which is most effective at the stoichiometric point.