Abstract
Ceramic preconverters are a viable strategy to meet the California LEV, ULEV and 1999 European Stage III standards. The ceramic preconverter lights-off quickly and is catalytically efficient. In addition, it can also survive the more severe thermomechanical requirements posed by its close proximity to the engine. This paper investigates the impact preconverter design parameters such as cell density, composition, volume, and catalyst technology have on emissions and pressure drop. The results demonstrate that ceramic preconverters substantially reduce cold start emissions. The preconverter durability is evaluated by both on-vehicle testing and hot vibration testing. Eight preconverters, following aging for 160,000 km on 3.0 and 4.0 liter vehicles, showed no significant degradation in their mechanical integrity with only minimal degradation of the catalytic activity. In addition, improved packaging designs have extended the life of ceramic preconverter systems to 100 hours in hot vibration testing at 75 g's, 185 Hz with an inlet gas temperature of 900°C.