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During combustion, organosulfur compounds typically contained in gasoline are converted to SO2. Over automotive emission control catalysts, the SO2 can be converted to other sulfur compounds such as H2S,COS, and H2SO4. The chemistry of sulfur over catalysts is a function of A/F as well as catalyst composition. Exhaust emission control catalysts are also poisoned by exhaust SO2. The present study probes the extent of poisoning as a function of A/F, fuel sulfur levels and noble metal composition. The effect of fuel sulfur levels (14-6000 ppm) during aging and evaluation of platinum/rhodium, palladium/rhodium and palladium-only three-way control catalysts was evaluated. Performance measurements are reported for both engine dynamometer and vehicle systems.

The dual requirement of high conversion efficiency and 50K mile durability for cordierite ceramic converters is achievable through optimization of washcoat and catalyst formulation. This paper presents new data for high temperature physical properties, light-off performance, conversion efficiency and pressure drop through an oval cordierite ceramic converter with triangular cell structure and two different washcoat formulations; namely standard vs high-tech. Both of the washcoat systems have a beneficial effect on strength properties with nominal impact on thermal shock resistance. Both the standard and high-tech catalysts provide identical light-off performance for CO, HC and NOx conversion. The high-tech washcoat and catalyst system, in particular, provides consistently superior conversion efficiency for CO, HC and NOx. The pressure drop across the catalyst depends on hydraulic diameter and is only 8% higher for high-tech washcoat than for standard washcoat.