Cross-metathesis of microbial oils for the production of advanced biofuels and chemicals

A range of microbial oils were cross-metathesized with ethene using Hoveyda–Grubbs second-generation catalyst. The products formed from the microbial oils were compared to alternative first- and second-generation oils. Upon separation, three separate fractions were produced: an alkene hydrocarbon fraction or aviation fuel fraction (AFF), a shorter-chain triglyceride fraction that upon transesterification was suitable as a road transport fuel (road transport fraction, RTF), and a volatile short-chain alkene fraction (gas phase fraction, GPF). The fuel fractions were purified through distillation and compared to the relevant fuel standards. Though there was variation for the RTF because of the presence of long-chain saturates, all the RTF produced fell within the ASTM standard for biodiesel. The AFF was found to be highly suitable for aviation, falling entirely within the DEF-STAN fuel standard. In addition, the AFF possessed an energy density higher than that of Jet A-1, whereas 1-decene was found to have an oxidative stability higher than that of jet fuel. Finally, the GPF was found to predominantly contain propene, butene, and pentadiene isomers, all of which have application in the polymer industry. With further development, this process could provide the basis for a microbial oil biorefinery for the production of sustainable biofuels and polymer precursors.