Cold flow properties for blends of biofuels with diesel and jet fuels

Twelve potential biofuel compounds were tested in mixtures with three diesel fuels and one jet fuel to determine the effects of different functional groups on low temperature properties. Functional groups evaluated include diesters, esters, ketones, and ethers; alkanes were used for comparison. The length of the hydrocarbon chains on either side of the oxygen-containing functional groups and branching were varied. Some test compounds are not anticipated to be commercial biofuels, but were compared to understand the effect of functional groups on cold flow behavior. were observed relating to the compound class or oxygen-containing functional group present in the compound. Generally, alkanes, ethers, esters, and ketones with a low melting point temperature decreased the cloud point temperature of a fuel. Adding diesters resulted in low temperature liquid–liquid immiscibility. Multiple methods were used to confirm the presence of two liquid phases with diesters, including cold filter plugging point measurements. These general behaviors are independent of chain length and branching, as long as the melting point temperature of the compound is not significantly higher than the cloud point temperature of the fuel.