Modeling and Optimization of Multi-functional Ammonia Slip Catalysts for Diesel Exhaust Aftertreatment

Ammonia slip catalysts (ASC) are used downstream of the NH3-selective catalytic NOx reduction (SCR) system, to minimize ammonia from transport sector SCR units. The ASC may consist an active layer for control, a with oxidation functionality conversion, or combination thereof, either as individual layers single mixed layer. Mathematical models such systems involve flow and mass transfer in monolithic channels well coupled reaction/diffusion processes layers. In this work, we develop single-channel 1D-1D (pseudo 2D) steady-state tank-in-series mathematical model up two Kinetics relevant reactions over Cu-Beta zeolite Pt/TiO2 layer, including SCR, oxidation, formation N2O, were derived based on extensive reactor study. was validated experiments using four different small-scale monoliths, showing good agreement between predictions experimental results. Comparison ten configurations 200 ppm NH3 at 300 °C shows that pure catalyst generate undesirable high N2O levels. best feature fast diffusion (a effective coefficient), thin top loading some catalyst, limit NOx.