Catalyst Selection for Lean Combustion Engines

A modeling procedure for selecting exhaust gas oxidation catalysts was applied to a lean air/fuel, high compression engine. The procedure was used to select the lowest cost catalyst that could meet given CVS C/H emission targets. The procedure consisted of 1) aging a variety of oxidation catalysts using an engine dynamometer, 2) measuring the conversion efficiencies of the aged catalysts during increasing and steady temperature conditions, 3) determining relevant properties of the exhaust gas at the catalyst inlet, 4) determining the activity parameters for oxidizing hydrocarbons. HC, and carbon monoxide, CO, on the aged catalysts, 5) predicting vehicle CVS HC and CO emissions as a function of catalyst volume, and 6) determining the most cost effective catalyst to meet a given CVS emission level as a function of the precious metal used, its concentration, the catalyst volume, and their incremental costs. The results of this procedure are valid only for the vehicle, catalysts and catalyst aging procedure used.