Computer Aided Assessment of Catalyst Ageing Cycles

In view of recent and future US and european regulations the design optimization of 3-way catalytic converters (3WCC) should also account for catalyst durability. The purpose of this paper is to extend the authors' approach for 3WCC modeling and evaluation in the direction of covering some aspects of ageing behavior. After a brief examination of the commonly accepted ageing mechanisms, a new methodology for the assessment of catalyst durability is formulated. This methodology takes into account the effect of thermal loading, high-temperature oxidation and poisoning of the catalyst. Based on the approach presented, along with the 3WCC and other related models and computer codes already in-use by the authors, a comparative assesment of engine bench ageing cycles may be computationally supported. Correlation of vehicle ageing cycles with engine bench cycles may also be accomplished as illustrated by a case study. As a second step, a methodology for tailoring fast engine bench ageing procedures to match road ageing conditions of a specific “engine - exhaust system - catalytic converter” system is outlined. The approach aims at providing more insight in catalyst deterioration phenomena in a way that could possibly be exploited by a variety of people ivolved in the automotive pollution control policy.