Abstract
The lean NOx trap (LNT) catalyst model for the purpose of Model-based development of LNT, which is one of the NOx purification devices for diesel exhaust gas, have been developed. This report focuses on the systematic modelling method of the redox reaction during LNT regeneration. Since many reactions proceed simultaneously on LNT catalyst, it is necessary to observe each reaction independently for determining the reaction rate constants. Therefore, we first classified reactions on LNT catalyst into six categories according to the reaction atmosphere and the active components. For modelling of one of them, the redox reactions in LNT regeneration, we developed a ″build-up method″ that identifying rate constants of each reactions step by step using genetic algorithm. The LNT model, developed according to a 15-step systematic procedure, was able to simulate accurately the concentrations of H2, CO, THC, NH3, NO, NO2, and N2O at outlet of LNT catalyst. The developed reaction model showed the importance of water gas shift and steam reforming in LNT regeneration. Furthermore, the importance of NH3 and N2O as intermediates in the NOx reduction process was also suggested.
