Biodiesel and Renewable Diesel Blends Oxidation by Diesel Oxidation Catalyst

Renewable and alternative liquid fuels are being evaluated for their equivalence with ultra-low sulfur diesel (ULSD) in terms of engine and emission control system performance. Our previous research showed an elevated lightoff temperature for diesel oxidation catalyst (DOC) and lower DOC thermal efficiency for biodiesel blends into ULSD with more than 20% biodiesel. Here we report a similar DOC performance study to gage the performance of blends of biodiesel and hydrocarbon renewable diesel (RD) also made from fats and oils feedstocks. The same DOC used previously was used to evaluate RD blends with biodiesel up to 60 vol% (B60R40) in decrements of 10%. The performance of the DOC was evaluated on a steady-state performance cycle and a transient lightoff curve. Similar to previous results, the performance of the DOC is significantly affected by even low blend levels of biodiesel. At low flow rates 50% (B50R50) and higher biodiesel blends have a poor performance defined as the lightoff temperature of the DOC progressively increasing with an increase in biodiesel fraction in the fuel blends. At mid and high flow rate, blends of 20% (B20R80) and higher have progressively worse performance. This is thought to be because of the higher boiling point of the biodiesel leading to poor evaporation of the fuel at lower DOC inlet temperatures.