Analysis of AdSCR Systems for NOx Removal During the Cold-Start Period of Diesel Engines

Herein, we extend the study of the AdSCR system (AdSCR = adsorption + selective catalytic reduction), consisting in a physical mixture of a conventional NH₃-SCR catalyst and of a NOx storage material. We have shown in previous work that an AdSCR system can capture and store NOx at room temperature from Diesel engine exhausts, and directly reduce them with ammonia at higher temperatures in the same unit. The present work aims at optimizing the system composition, in order to minimize the release of NOx in the low temperature window. Results from cold start mimicking experiments show that the full storage time, i.e. the zero-emission period where the fed NO is completely adsorbed by the catalyst, is affected only by the amount and the composition of the storage material, whereas the NOx storage efficiency is controlled by amount and nature of both components of the physical mixture.