Radiometric Determination of Platinum and Palladium Attrition from Automotive Catalysts

Automotive exhaust gas catalysts contain platinum and palladium as the active material on an alumina substrate. The loss rate of the active material from the catalyst under vehicle operating conditions was determined with a radiometric method in which radioactive platinum and palladium were used as tracers. Experiments with a commercial catalyst made radioactive by irradiation in a nuclear reactor indicated that a maximum of about 6 percent of the active material would be lost from the catalyst in 80,000 km. Experiments with a laboratory prepared catalyst containing 195mPt and 103Pd indicated that about 10 percent of the active material lost was water soluble, possibly in the form of halides.