Dynamic behavior issues in three-way catalyst modeling

Mathematical modeling of three-way catalytic converter (3WCC) operation is used increasingly in automotive catalyst and converter systems optimization. The majority of these models employ a “quasi-steady” approach in the reaction kinetics computations, which is useful in predicting real-world performance of the catalyst. However, certain improvements produced by the application of specially tuned redox oscillations cannot be predicted. The approach presented embodies certain types of dynamic phenomena in an existing 3-WCC quasi-steady model. The dynamic model based on this approach is validated against data in the literature and experimental results. It is confirmed that the catalyst behavior under dynamic exhaust composition conditions significantly differs from predictions under the quasi-steady-state assumption. Oxygen storage and the transient character of water gas shift reaction affect dynamic behavior. The results of this investigation encourage further application of mathematical modeling in such areas as lambda control strategy optimization that lie beyond the scope of traditional 3WCC models.