Power-bench demonstration of the Pt-catalysed C3H6-SCR of NOx in a diesel exhaust Original Research Article

The SCR of NOx by C3H6 using a 0.1 wt.% Pt/Al2O3 catalyst has been successfully performed under real diesel gas streams in a power bench. The influence of some experimental variables affecting NOx, CO, and THC conversions, such as hydrocarbon concentration, reaction temperature and space velocity effect, are discussed. 96% NOx conversion has been reached under optimum conditions. The highest NOx conversion level is maintained in the range 250–325 °C but slightly higher temperature (350 °C) is desired to ensure a stable temperature and complete CO and THC removal. An optimum THC concentration is found (1500 ppm THC), higher THC concentration having a negative effect in the NOx conversion. From experiments performed at different GHSV, the reactor volume required for total NOx removal in a real exhaust stream has been estimated to be 6.5 L. Additionally, the effect of CeO2 on platinum behaviour has been studied, concluding that it enhances N2 formation as NOx reduction product with respect to N2O, but lowers the platinum activity for NOx reduction and CO and THC oxidation.