Abstract
To construct the elementary reaction model of Pt/CeO2 catalyst as lean NOx trap catalyst, numerical simulation was performed. Each Arrhenius parameter of CO, C3H6, and NOx elementary reactions was calibrated to closely match the results of the catalytic activity measurements. The experiment was carried out in a tubular quartz reactor with catalyst powder. The elementary reaction model was calibrated to the measured results of 11 simple gas mixtures, such as the CO+O2 reaction. Moreover, the model’s accuracy was increased by theoretical approach of the first principle calculation. The elementary reaction model was constructed with 87 reactions including 14 radical reactions, 11 CO reactions, 25 C3H6 reactions, and 37 NOx reactions. Good agreement was achieved between the experimental data of complex gas mixtures, such as engine exhaust gas, and the simulated results. In addition, a model for the deterioration behavior on thermal aging was constructed utilizing experimental results and data mining. Pathway analysis using the rate of production was performed for the NOx reduction reaction with each precious metal, Pt, Pd, and Rh. It was found that the rate-determining step of Pt and Pd is the reaction with CO, while that of Rh is C from C3H6 decomposition.
KEYWORDS – Automotive exhaust catalyst, Elementary reaction model, Reactor experiment, Arrhenius expression, Reaction pathway analysis