| The focus of this work is the development of a framework for predicting the effects of catalyst (Pt) loading, composition and interaction between catalytic components (Pt and BaO) on the storage and reduction of nitrogen oxides (NOx) on Pt/BaO/Al2O3 catalysts. Various sub-systems were studied to develop a microkinetic model of NO-H2-O2-NH 3 systems.;A 13-step microkinetic model was developed to describe the kinetics of anaerobic NO reduction by H2 on Pt/Al2O3. The 13-step microkinetic model was then expanded with another four lumped steps to account for O2 and NH3 effects. The model predicted experimentally observed conversion and selectivity trends of NO/H2, NH3/O2, NH3/NO and NH3/H 2/NO systems without involving rigorous optimizations. It was shown that H2 is a more efficient NO reductant than NH3. It was also found that external mass transfer has significant effects.;The transient one-dimensional two-phase model was used along with a microkinetic model for storage and cyclic NSR simulations on PtBaO/Al2O 3 catalyst. A NOx storage model with two types of barium sites was developed. The model accounted for NO oxidation on Pt, NOx storage reactions between gas and barium surface species, and spillover reactions at the interface of Pt and BaO sites in the proximity of Pt. The model captured the major trends of experimental measurements. The modeling study suggests that the dependence of proximal barium sites on Pt concentration is not linear but of a lower order.;A microkinetic model for stored NOx regeneration was also developed using NO2 as the spillover species from proximal BaO to Pt surface. The model was used to simulate an NSR process using "anaerobic" regeneration with H2 as the reductant. The model predictions captured the most important trends of experimental results, such as separated H2 and NH 3 peaks at different reactor lengths, accelerated H2 breakthrough along the flow direction, and NO pulse at the beginning of the rich phase. |
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