Development of chemically consistent models of NH3-SCR reactions over Fe-zeolite catalysts for the aftertreatment of Diesel engine exhausts

experimental and modeling studies of a commercial Fe-promoted zeolite catalyst in the NO/NO2/N2O-NH3 SCR reactions are herein summarized. Transient kinetic runs are used to identify the particular reactivity features typical of Fe-zeolites and a kinetic model of the SCR reacting system that takes into account all of these features is developed and validated. In particular, the model accounts for dual-site ammonia adsorption/desorption at very low temperature, hysteresis effects of NOx conversion in the NO-NH3-O2 reacting system at low-T, apparently non-stoichiometric NH3/NO consumption ratios in the Standard SCR reaction, and reactivity of N2O.