Transient Kinetic Modeling of the Ethylene and Carbon Monoxide Oxidation over a Commercial Automotive Exhaust Gas Catalyst

The transient kinetics of ethylene oxidn. by O over a com. Pt/Rh/CeO2/g-Al2O3 3-way catalyst were modeled. Expts. were carried out in a fixed-bed microreactor with 2 sep. inlets, enabling alternate feeding of ethylene and O with frequencies ?1/4 Hz. The exptl. 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 O 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 expts. quant. This model was combined with the published model for transient CO oxidn. over the same catalyst, which enables one to predict the results of simultaneous ethylene and CO oxidn. Both components react in rather distinct zones, with ethylene being converted only when CO oxidn. is almost complete. [on SciFinder (R)