A Comprehensive Study on DOC Selection for Euro 6 Compliant Heavy Commercial Vehicles

Euro 6 emission norms are getting implemented in India from April 2020 and it is being viewed as one of the greatest challenges ever faced by the Indian automotive industry. In order to achieve such stringent emission norms along with top performance for vehicle, a good strategy should be incorporated to control system out NOx emissions and soot regeneration. Extruded Vanadium catalyst is deployed for this passive regeneration system with DOC (Diesel Oxidation Catalyst), DPF (Diesel Particulate Filter) and SCR (Selective Catalyst Reduction), where the amount of catalyst loading in DOC plays an apex role in deciding conversion efficiency of SCR and passive regeneration capabilities. This study mainly focuses on the impact of catalyst loading of DOC over SCR efficiency. NO₂ to NOx ratio should be close to 0.5 for optimum conversion efficiency of SCR. Catalyst loading in DOC decides the amount of NO₂ coming upstream to SCR. Higher amount NO₂ from DOC will benefit in passive regeneration but it will also inhibit NOx conversion rate. An optimum trade-off should be made for the effectiveness of dual emission control. Moreover, this study has also included the effect of prolonged aging of catalyst (1000 hours) over its efficiency. With aging of catalyst, it was found that there is a drop in NO oxidation by 8-10% and improvement in SCR efficiency by 5-6% compared to the fresh catalyst system.