Development and validation of a model for wall-flow type selective catalytic reduction system

The two-way diesel particulate filter (DPF)/selective catalytic reduction (SCR) emissions-reduction system has recently been extensively studied due to its potential cost savings and packing flexibility. Unlike a conventional emissions-reduction system that consists of a DPF and an SCR for reduction of both particulate matter and nitrogen oxides (NOx), this two-way system incorporates SCR function into a wall-flow DPF as a single device by coating SCR catalysts into the filter wall of the DPF. Such a combinatorial system has the advantage of lower system volume and cost, since exhaust gas undergoes soot filtering and NOx reduction reaction simultaneously as it passes through the channels and filter wall. In this work, the mathematical formulations which govern the physical and chemical phenomena in the two-way DPF/SCR are derived and a computer simulation model is developed based on these formulations. The model has been validated and tested with experimental data from a reactor flow bench in a systematic manner, which captures ammonia adsorption/desorption and NOx reduction of the blended two-way DPF/SCR device.