Aging of Automotive Catalysts-Development of a Practical Model

Aging characteristics of automotive catalysts are experimentally investigated under a few steady-state fast aging conditions using a test system configured around an engine and a dynamometer. Temperature of the engine exhaust gas at the inlet, outlet and 4 points within the catalytic converter are measured under various engine operating conditions. Result of the measurements indicates that the temperature is fairly uniform along the center line of the converter during steady-state engine operations. Conversion efficiency of the catalytic converters are monitored as an indicator for deactivation under steady but harsh aging conditions of high temperature and various air-fuel ratio. The conversion efficiencies measured during the aging operations are then used to calibrate a preliminary model which is proposed herein to predict, in principle, the extent of degradation under arbitrary aging conditions as a function of temperature and oxygen concentration of the feed gas.