A System Simulation Study of the Enhanced-SCR Reaction

This study addresses fundamental and practical aspects of the Enhanced-SCR reaction over a Fe-zeolite SCR catalyst. The key mechanistic steps responsible for the improvement of the DeNOx activity at low temperatures are analysed, and a system simulation model is developed to assess its potential for NOx conversion improvement in heavy-duty aftertreatment systems. It was found that the ammonium nitrate additive can dramatically improve the low-temperature DeNOx activity of a Fe-zeolite catalyst, by generating in situ NO2 readily. Such NO2 can then react in the Fast-SCR reaction, which explains the enhanced low-T SCR activity. The simulation of a complete heavy-duty aftertreatment system with a dedicated AN injection showed the potential of the apparatus, in both cold and hot WHTC.