Abstract
The SCR(Selective Catalytic Reduction) system reduces diesel NOx emissions through the catalytic reactions using ammonia/urea or hydrocarbon as a reductant. The present study mainly deals with the ammonia/urea SCR using a commercial zeolite-based catalyst. In modeling the catalytic reactions occurring in the ammonia/urea SCR, the adsorption and desorption of ammonia onto the active sites over a broad temperature must be modeled realistically, because ammonia takes an important role in the DeNOx processes. Thus, in the current study, the transient modeling on the adsorption and desorption kinetics of ammonia is first carried out as well as the heat and mass transfer modeling. And then, the transient modeling on various reactions occurring in the ammonia/urea SCR is also performed. On the basis of these mathematical modeling and numerical tools, the kinetic parameters of the ammonia adsorption and desorption are newly calibrated with the powder-phase TPD experimental results performed over the commercial Fe ion-exchanged zeolite-based catalyst. And then, with applying these kinetics describing the ammonia adsorption and desorption, kinetic parameters for the various model reactions such as ammonia oxidation, NO SCR reaction, NO2 SCR reaction and NOx SCR reaction in the ammonia/urea SCR are also newly determined with the coreout monolith SCR experimental results over the commercial Fe ion-exchanged zeolite-based catalyst. Finally, using the obtained kinetic parameters, its validations are achieved with a comparison between the calculated and measured results.
Keywords: Kinetic Parameter Estimation, Ammonia/Urea, SCR, DeNOx, Zeolite, Catalyst