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The effects of oil derived poisons and thermal degradation on three-way automotive catalysts is investigated. Dynamometer rapid aging test (RATsm) schedules that incorporate both thermal and oil-derived poison degradation are used to age catalysts for FTP emissions studies. This paper presents three investigations. Vehicle aged converters are analyzed to determine the axial phosphorus distribution through out the catalyst. These phosphorus profiles are compared to dynamometer RATsm aged catalyst. Also, 27 converters were RATsm aged on three different RAT schedules at three different accelerated poison levels. The amount of phosphorus on the catalyst is compared to the amount of equivalent oil consumed by the aging engine. Finally, 24 converters were aged on three different RATsm schedules to determine the effects of catalyst volume, aging temperature and oil derived poisoning on FTP emissions using both Pd and Pt/Rh catalyst technologies.

Automotive catalysts deactivate by thermal and poison mechanisms. Thermal degradation reduces catalyst efficiency by both agglomeration of precious metals and by reduction in surface area of the washcoat. Engine oil derived poisons degrade catalyst performance by coating the outer surface of the washcoat. Numerous catalyst technologies are aged using accelerated dynamometer aging schedules that simulate the thermal and poison degradation of field aged catalysts. Pd, Pd/Rh, Pt/Pd/Rh, and Pt/Rh catalyst technologies are aged and evaluated on various rapid aging test (RATsm) schedules in an effort to ascertain what catalyst technologies may be best for low temperature and high temperature applications. The performance of these catalyst technologies are evaluated on an air/fuel sweep test and a 3.8L auto-driver FTP stand. Results show that the RATsm schedule applies a phosphorus poison distribution (due to engine oil consumption) similar to vehicle aged catalysts.