2022-Global Kinetic Modeling of a Commercial DOC Based on a Reduced Synthetic Gas Bench Protocol

Various techniques are constantly being devised to accelerate model generation leading to shorter product development cycle. This work proposes and implements a reduced synthetic gas bench (SGB) test protocol for a commercial Pt-Pd diesel oxidation catalyst (DOC) that can be used to develop global reaction kinetics. The kinetics thus developed were implemented in a 1D model to predict DOC emissions accurately over a wide operating window. Hydrocarbons (HCs) in the exhaust were categorized as Propylene (C₃H₆) representing partially oxidized hydrocarbons and n-Decane (C₁₀H₂₂) representing unburnt fuel. Test protocols were defined using the order of inhibition of the various species present in the exhaust, namely, CO, NO_x (NO+NO₂) and HC for the specific reaction under consideration. The oxidation reactions for CO and HCs were found to be inhibited competitively by CO and HCs; both the NO_x species inhibited these reactions to the same extent. The NO oxidation reaction was found to be heavily inhibited by the hydrocarbons. In addition to the oxidation kinetics (by O₂ and NO₂), and the N₂O formation kinetics, nitrate storage and release kinetics were modeled to account for scenarios with high NO₂ at low temperature. Simple root mean square error (RMSE) based objective function definition was used to fit the experimental data and generate reaction kinetics. The reaction kinetics thus developed were validated with (a) simulated multispecies datasets collected on gas bench representing various engine out exhaust gas mixtures and (b) using transient engine dynomometer data.