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A one-dimensional (1-D) micro-kinetic reaction model with considering mass transport inside porous washcoat was developed to promote an effective development of multi-functional catalysts. The validation of this model has been done successfully through the comparison with a set of basic experiments. A numerical simulation study was conducted for the various catalyst configurations of three-way catalysts under Federal Test Procedure (FTP75) condition. It was found that a double layer type had a significant advantage in the total mass emissions, especially in NOx emissions. The reaction mechanisms in these catalysts were numerically clarified from the view point of detailed reaction dynamics. We concluded that the utilization of the numerical simulation with the detailed chemistry was effective for the optimization of catalyst design.

In this research we developed surface kinetic model with detailed reaction mechanisms for simulating reaction dynamics of NOx Storage& Reduction (NSR) Catalyst and three-way catalyst (TWC). Simulation results showed that surface site coverage strongly dominates catalytic reaction characteristics especially in transient state. So we confirmed that the surface kinetic model could play important roles in a useful tool for understanding detail reaction dynamics and searching the optimized operating conditions in the development of automotive catalysts which was always exposed to transient conditions. And the detailed reaction mechanisms in TWC and NSR catalyst were discussed on the basis of the calculated surface site coverage.

A reduced chemical kinetic model has been developed using temperature history measured by Coherent Anti-Stokes Raman Spectroscopy (CARS) and sensitivity analysis. Predictions of knock occurrence by this model show that the chemical role of residual gas and the intake flow have little effect on the knock occurrence crank angle. Furthermore, the effectiveness of the combustion period and the unburned gas temperature before spark ignition on the torque at trace knock limit (TTKL) has been clarified Under certain conditions, it is shown that the increase in torque, caused by the combustion duration shortened by ∼25%, is negated by the temperature rise of ∼15K before spark ignition.

The emission characteristics of hydrocarbons during the cold start and the warm-up have been investigated. Timed sampling of hydrocarbon emissions upstream and downstream of a close-coupled catalytic converter have been carried out. The experimental results show that the emission characteristics of hydrocarbons are influenced by both the engine operating conditions and the heating characteristics of the catalytic converter. In the case of engine-out hydrocarbons, the total amount of hydrocarbons drastically decreases but the percentage contribution of the C2-C4 olefins to the engine-out hydrocarbons increases as the warm-up proceeds. Since these olefins have relatively high maximum incremental reactivity (MIR) factors, the specific reactivity (SR) of the engine-out hydrocarbons gradually increases during the warm-up. The adsorption and desorption processes of the engine-out hydrocarbons on the catalyst occur before the catalyst light-off.

The effects of fuel properties and emission control systems on exhaust hydrocarbon emissions have been studied. Using fourteen fuels with different properties, exhaust hydrocarbon emissions were measured for the two vehicle types with different emission control systems, under body catalyst and closed coupled catalyst, under the Federal Test Procedure. The fuel properties included high and low concentrations of olefins and aromatics as well as high and low T90. In addition, two fuels contained MTBE. The hydrocarbon emissions were discussed from the view point of the ozone reactivity and ozone formation potential. The results show that the high ozone reactivity of exhaust emissions are mainly caused by the olefins and aromatics in fuels. And also, the effects of fuel property change on exhaust emissions for the vehicle with an under body catalyst are more sensitive than the case of the vehicle with a closed coupled catalyst.