Technical Paper
Deactivation of Three-Way Catalysts by Fuel Contaminants - Lead, Phosphorus and Sulfur
1979-02-01
790942
Poisoning of a typical platinum-rhodium (Pt-Rh) automotive three-way catalyst (TWC) was determined as a function of lead (Pb), sulfur (S) and phosphorus (P) fuel levels, thermal aging and sulfur dioxide (SO2) content in the evaluation fuel. In laboratory studies catalysts were durability tested in pulse-flame reactors followed by flow-reactor activity measurements. Engine dynamometer-aged catalysts were evaluated on a slave vehicle. For Pt-Rh TWCs the activities for nitric oxide (NO), carbon monoxide (CO) and hydrocarbon (HC) conversions were poisoned by trace levels of 1-6 mg Pb/gal (0.3 - 1.6 g/m3). When the peak temperature in the aging cycle was increased from 730 to 870°C (1346 to 1598°F), the activities improved significantly. In an attempt to mimic the effect on TWCs of misfueling with Pb levels typical of commercially available leaded fuels, TWC activities were severely poisoned.
