Impact of high sulfur fuel and de-sulfation process on a close-coupled diesel oxidation catalyst and diesel particulate filter

The application of more stringent emission regulations for passenger cars in Asian and South American countries is challenging due to the presence of low-quality diesel fuel, which enhances the risk of deactivation of aftertreatment systems due to its higher sulfur content. In this context, the impact of high sulfur fuel on the performance of a close-coupled Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) was experimentally tested for degreened, sulfated and de-sulfated real size aftertreatment components, through engine tests carried out on a highly-dynamic engine test rig, allowing to reproduce the transient operation of the engine and of the aftertreatment system during type approval driving cycles. In order to assess the impact of sulfur poisoning, a specific poisoning procedure was adopted which resulted in different sulfur poisoning levels. The impact of different space velocities on degreened, poisoned and de-sulfated system was examined and compared considering light-off curves for CO and HC. The poisoned system was found to be worst effected due to increasing space velocities. In addition, the ability to recover the performance of aftertreatment system after regeneration through a proper de-sulfation strategy was evaluated with respect to fresh, degreened, catalyst. The aftertreatment system recovered its efficiency almost completely after the de-sulfation procedure was carried out.