Thermophysical properties of biodiesel and related systems: Low-pressure vapor + liquid equilibrium of methyl/ethyl soybean biodiesel

• Boiling point temperatures for soybean FAME and FAEE measured in the pressure range of (6.7 to 66.7) kPa.
• Investigated systems presented a non-ideal behavior, with positive deviations from Raoult’s law.
• Experimental data satisfactorily represented by the UNIQUAC model.

In this work, experimental boiling point temperatures for pseudo-binaries (methyl/ethyl biodiesel + methanol/ethanol) and pseudo-ternaries (methyl/ethyl biodiesel + methanol/ethanol + glycerol/water) systems were measured at several pressures ranging from (6.7 to 66.7) kPa using an Othmer-type ebulliometer. The systems investigated show a non-ideal behavior, with positive deviations from Raoult’s law. It was observed that the addition of up to 10 wt% of alcohol (methanol or ethanol) led to a significant decrease in the boiling point temperature of the systems. The UNIQUAC model was successfully used to represent the experimental results, with an overall average deviation between experimental and calculated boiling temperature values of 0.004%.