Numerical Simulation of NO/NO2/NH3 Reactions on SCR-Catalytic Converters:Model Development and Applications

A 1D+1D numerical model describing the ammonia based SCR process of NO and NO₂ on vanadia-titania catalysts is presented. The model is able to simulate coated and extruded monoliths. Basing on a fundamental investigation of the catalytic processes a reaction mechanism for the NO/NO₂ - NH₃ reacting system is proposed and modeled. After the parameterization of the reaction mechanism the reaction kinetics have been coupled with models for heat and mass transport. Model validation has been performed with engine test bench experiments. Finally the model has been applied to study the influence of NO₂ on SCR efficiency within ETC and ESC testcycles, Additional simulations have been conducted to identify the potential for catalyst volume reduction if NO₂ is present in the inlet feed.