The transient kinetics of ethylene oxidation by oxygen over a commercial Pt/Rh/CeO2/γ-Al2O3 three-way catalyst were modeled. Experiments were carried out in a fixed-bed microreactor with two separate inlets, enabling alternate feeding of ethylene and oxygen with frequencies up to 1/4 Hz. The experimental conditions resemble the cold-start period of an Otto engine in a car. Two types of adsorbed ethylene species seem to exist. A selective catalyst deactivation for oxygen adsorption, due to deposition of carbonaceous species, was found. A kinetic model was developed, based on elementary reaction steps, that allows one to describe the experiments quantitatively. Furthermore, this model was combined with the published model for transient carbon monoxide oxidation over the same catalyst, which enables one to predict the results of simultaneous ethylene and carbon monoxide oxidation. Both components react in rather distinct zones, with ethylene being converted only when carbon monoxide oxidation is almost complete.

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