Deterioration of Three-Way Catalysts

Abstract

The deterioration of the activity of three-way catalysts during use is an important characteristic because the Federal emission standards require that performance be maintained for 80,000 km, as described earlier. Three-way catalysts lose activity both due to thermal effects and due to poisoning by contaminants in exhaust, namely phosphorus, lead, and sulfur. Combined poisoning and thermal effects and interaction among poison species complicate deterioration studies. A considerable incentive exists to minimize catalyst deterioration. If deterioration were eliminated, catalysts could have lower noble metal loadings and vehicles might be calibrated for greater fuel economy.