Activity of Prototype Catalysts on Exhaust Emissions from Biodiesel Fuelled Engines

A prototype catalyst has been developed and integrated within the aftertreatment exhaust system to control the HC, CO, PM and NOx emissions from diesel exhaust gas. The catalyst activity in removing HC and nano-particles was examined with exhaust gas from a diesel engine operating on biodiesel - Rapeseed Methyl Ester (RME). The tests were carried out at steady-state conditions for short periods of time, thus catalyst tolerance to sulphur was not examined. The prototype catalyst reduced the amount of hydrocarbons (HC) and the total PM. The quantity of particulate with electrical mobility diameter in nucleation mode size < 10nm, was significantly reduced over the catalyst. Moreover, it was observed that the use of EGR (20% vol.) for the biodiesel fuelled engine significantly increases the particle concentration in the accumulation mode with simultaneous reduction in the particle concentration in the nuclei mode. The effectiveness of the prototype catalyst in reducing PM from the combustion of biodiesel was dependent on the engine operating condition and EGR. However, up to 50% and 30% reduction in total particulate number and mass, respectively, was seen due to oxidation of the soot free PM (nuclei) and organic carbon from the rest of the PM. When EGR was used the catalyst effectiveness in controlling PM and especially total number was reduced to as low as 5%, due to increased PM concentration and modified PM composition. The results suggest that the use of this prototype catalyst can aid aftertreatment system performance and the control of environmental pollution.