Volatility and boiling points of biodiesel from vegetable oils and tallow

Quality control of fuel-related properties of Biodiesel, such as volatility, is needed to obtain consistent engine performance by fuel users. The vapor pressures and boiling points of selected methyl esters and vegetable oils are proposed as quality control metrics for Biodiesel. This type of data was obtained by a rapid new method using thermogravimetric analysis (TGA). One atmosphere boiling points (bps) and temperature-dependent vapor pressures from 1 atm down to 5.332 kPa (40 mmHg) were measured for methyl and ethyl esters of rapeseed oil, canola oil, soybean oil, and tallow. Boiling points (1 atm) ranged from 340°C to 375°C. Methyl and ethyl esters of a given oil differ by ca. 5°C in bps. These results are discussed in terms of the fatty acid composition of the esters and oils. Calibrations showed that the TGA/laser orifice capsule method gave accuracy of ±5%.