Evaluation of Sulfation and Lean/Rich Desulfation of a NOx Storage Reduction Catalyst Using an Advanced NSR Model

This work focuses on the usage of a physico-chemical model which can describe the sulfation and lean/rich desulfation process of a NOx Storage Reduction (NSR) catalyst. The NSR model was developed and calibrated using findings and data obtained from Synthetic Gas Bench (SGB) experiments. It was clarified that sulfur can be stored on different storage sites depending on the sulfation temperature. During lean/rich desulfation, sulfur components are released from the front part of the NSR catalyst and are re-adsorbed on the rear part.
This trend can be captured by the model, leading to accurate prediction of sulfur release timing and SO2/H2S ratio. The developed model was then used to simulate different lean/rich desulfation strategies, where rich duration, temperature and reducing gas (H2) composition were varied. The role of each parameter was identified and explained based on the proposed reaction pathways. Finally, simulations were carried out in order to predict the effect of fuel sulfur content in the axial sulfur distribution after consecutive sulfations under transient driving conditions