A model-based analysis of washcoat distribution on zoned coated gasoline particulate filters

The integration of three-way catalysts (TWC) and gasoline particulate filters into a single so-called coated GPF (cGPF) can decrease the necessary packaging volume and costs in exhaust gas aftertreatment systems. Similar to classical TWCs, it is possible to introduce advanced coating technologies, in the presented case zoning, which creates zones of high and low washcoat loading, resulting in a filter with an axial non-uniformity of the washcoat distribution. In addition to zoning, a filter can either be coated solely in-wall or have a partially or fully on-wall coating, which leads to a variety of coating configurations. To investigate the impact of the coating configuration, a previously published validated cGPF model is applied to evaluate the pressure drop, high load conversion, and light-off performance of fresh cGPFs. The simulations reveal an enhanced light-off at steady-state conditions if more washcoat is deposited at the front part of the filter or on the inlet channel. Under transient conditions, however, a filter with a catalytic layer on the outlet channel performs best.