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A two-brick gasoline engine aftertreatment system with advanced washcoat technology was developed for LEV2 PZEV2 legislation, and its application to the upcoming LEV3 SULEV30 emission standard was demonstrated. The system was comprised of 1) a palladium only catalyst in the close coupled position with improved catalytic performance and high phosphorus poisoning resistance compared with 09MY technology, and 2) an underfloor palladium rhodium catalyst technology in which the nitric oxides (NOx) reduction activity was enhanced by preventing the deactivation of rhodium under rich conditions. As a result, the palladium only + palladium rhodium catalysts system met the LEV2 PZEV standard with three quarters of the PGM and half the rhodium of the system used on the Honda 09MY Accord vehicle. The system was also demonstrated to meet the LEV3 SULEV30 standard with some margin.

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.

With the ever-increasing stringency of emissions regulations, automotive three-way catalysts (TWCs) require much faster light-off performance and higher warmed-up activity than before. Most automotive manufacturers are considering the adoption of close-coupled catalyst systems as a means of dealing with cold start emissions and need the catalyst to have improved thermal durability. In this paper, a new Pd/Rh is reported to be suitable for high temperature application. Due to the recent increasing Pd metal cost, a Pt/Rh with equivalent or better TWC performance needs be developed to balance the PGM usage. A current Pt/Rh catalyst seems to possess comparable TWC performance to the new Pd/Rh catalyst when the catalysts are aged at 900°C. However, aging at a temperature higher than 900°C significantly deactivated the activity of the Pt/Rh catalyst to a point that is much worse than the Pd/Rh catalyst.