Durability of Monolithic Auto Exhaust Oxidation Catalysts in the Absence of Poisons

A study was undertaken to determine the thermal stability, in the absence of poisons, of a PTX®-Type IIB monolithic oxidation catalyst and to demonstrate durability on a vehicle by actual road testing. Effective control of emissions of hydrocarbons and carbon monoxide for 50,000 miles was achieved in the absence of system or engine malfunctions. No increase in carbon monoxide emission and a gradual increase in hydrocarbon emission was seen over this period. The increase in hydrocarbon emission was compared to that observed for a series of catalysts, hydro-thermally aged in the laboratory, indicating that the gradual increase was due primarily to thermal effects.

An analysis of the lead distribution in lead-free gasoline was made, indicating that with 0.05 grams per gallon maximum lead level (per EPA regulations) less than 0.03 grams per gallon would be valid for certification of automobiles.