Effect of Air-Fuel Ratio Modulation on Conversion Efficiency of Three-Way Catalysts

The widening of the selectivity windows of a three-way catalyst under A/F ratio modulation was shown to result from retention of adsorbed species on catalyst surfaces and their subsequent reaction with gas-phase reactants. A reaction model was developed based on adsorption properties of CO, HC and NO_x and by computer simulation, the conversion efficiencies of CO, HC and NO_x under A/F ratio modulation were calculated. The calculated and experimental results were in good agreement.