Model-Based Analysis of TWC-Coated Filters Performance

The wall flow filter technology is already an important element in gasoline engine emissions control. In addition to the filtration functions, the active catalytic coating can contribute to the reduction of gaseous emissions slipping from the upstream three-way catalytic converters (TWC). The substrate and coating technology require precise engineering to achieve the emission target without sacrificing fuel penalty associated with excessive backpressure and active regeneration. The present contribution addresses the main challenges in developing predictive models supporting the design and control of coated gasoline particulate filters (cGPFs), including filtration and pressure drop, soot oxidation, and effects of ash. The effect of soot and ash on TWC functions as well as the O₂ competition between soot and the reactive surface are studied by analyzing the coupled transport–reaction processes at wall scale. The modeling study is supported by measurements with filters of different cell structures and washcoat amounts performed under steady-state and transient modes.