(405a) Lean NOx Reduction By H2/CO/C3H6 Using NSR and SCR Catalysts

Kota, A. S. - Presenter, University of Houston
Luss, D., University of Houston
Balakotaiah, V., University of Houston

Transient NOx reduction performance of NSR and SCR catalysts is studied under adiabatic conditions using 1+1 dimensional two phase model. In the NSR catalyst, NOx is stored under lean conditions on the model Pt/BaO/Al2O3 catalyst and subsequently regenerated by a rich mixture of H2, CO and C3H6. A micro-kinetic reaction scheme is developed based on literature reported steady state and cyclic experimental studies of both NOx Storage and Reduction (NSR), and Selective Catalytic Reduction (SCR) processes. The kinetic parameters are initially estimated for each reductant separately, and are then modified based on comparison with experimental results. Mechanistic analysis of the reaction scheme provides clear insights into the dependence of NOx reduction efficiency on feed temperature and molar ratio of reducing agents. The model is able to reasonably accurately predict the NOx conversion and selectivities observed during the experimental studies. The kinetic scheme is further used to investigate the behavior of coupled NSR-SCR catalysts and study the effects of various parameters like cycle time, rich feed ratio, feed temperature, precious metal loading and catalyst architecture on NOx conversion under both aerobic and anaerobic conditions. Spatio-temporal concentration and temperature profiles are analyzed and used to determine the optimum operating conditions for the coupled catalysts, especially at low temperatures.