Technical Paper
Cold Start Performance and Enhanced Thermal Durability of Vanadium SCR Catalysts
2009-04-20
2009-01-0625
For diesel applications, cold start accounts for a large amount of the total NOx emissions during a typical Federal Test Procedure (FTP) for light-duty vehicles and is a key focus for reducing NOx emissions. A common form of diesel NOx aftertreatment is selective catalytic reduction (SCR) technology. For cold start NOx improvement, the SCR catalyst would be best located as the first catalyst in the aftertreatment system; however, engine-out hydrocarbons and no diesel oxidation catalyst (DOC) upstream to generate an exotherm for desulfation can result in degraded SCR catalyst performance. Recent advances in vanadia-based SCR (V-SCR) catalyst technology have shown better low temperature NOx performance and improved thermal durability. Three V-SCR technologies were tested for their thermal durability and low-temperature NOx performance, and after 600°C aging, one technology showed low-temperature performance on par with state-of-the-art copper-zeolite SCR (Cu-SCR) technology.