| We modify the literature kinetics to correctly predict the H2 light-off at room temperature, selectivity towards CO oxidation before the simultaneous light-off of CO and H2, the enhancement effect of H2, and the inhibiting effect of CO on light-off in a CO-H 2-O2 system.;Modeling and experimental studies on model Pt/Al2O3 and Pt/BaO/Al2O3 catalysts are performed to elucidate the kinetics of NO oxidation. Pretreatment experiments indicate that NO 2 is responsible for the deactivation of the catalyst. A global kinetic model is proposed which includes the inhibiting effect of NO2 on NO oxidation. The importance of including coverage of NO in the global model at low temperatures is shown.;A global kinetic model for NOx storage and reduction for the case of anaerobic regeneration with hydrogen is developed. The existence of two different types of BaO sites on the catalyst is proposed. The model captures the formation of NH3 and the NH3 concentration fronts, which reveal the reaction of NH3 formed upstream with the stored NOx downstream of the H2 front. The lower diffusivity of NH3 as compared to H 2 is shown to be responsible for the wider width of the NH3 front and earlier appearance of NH3 in the effluent than H2.;A crystallite-scale model is incorporated into a reactor-scale model to study the effect of Pt dispersion and temperature during the regeneration of a lean NOx trap (LNT). The model shows that an increase in the Pt dispersion increases the interfacial perimeter between Pt and Ba. The experimental data is explained by the localized stored NO x gradients in the Ba phase. The rate determining process during the regeneration is found to be the diffusion of stored NOx within the Ba phase. The model predicts that the highest amount of NH 3 is produced by the low dispersion catalyst at high temperatures, by the high dispersion catalyst at low temperatures, and by the intermediate dispersion catalyst at intermediate temperatures, which is consistent with the experimental data. Finally, a novel design is proposed to maximize the amount of NH3 in the effluent of a LNT, which can be used as a feed to a selective catalytic reduction (SCR) unit. |
