Recent experimental studies on noncatalytic transesterification have shown that high reaction rates, which justify the commercial application of this process, can be obtained if the operating conditions are above the critical pressure and temperature of methanol. Although it is generally agreed that temperatures of >550 K and high methanol/oil ratios are required to obtain high conversions and high reaction rates, there is disagreement in the literature regarding the operating pressure, the assumed phase conditions, the use of co-solvents, and the justification of the sudden increase of rate of reaction with temperature. In the present work, the reactor phase transitions are directly observed in a double-windowed cylindrical reactor and the conversion to methyl esters is measured. From direct observations and the modeling of the phase behavior, a better understanding of the supercritical methanol transesterification process is obtained.

In the present work, the transesterification of non-edible oil with methanol and ethanol is studied. The reactor phase transitions are directly observed in a double windowed cylindrical reactor and the conversion to fatty esters is measured. The optimization of the process conditions was carried out based on a statistical design of experiments where the key process variables were studied over different ranges to obtain a reliable model for the efficiency of the reaction as a function of reaction time, temperature, pressure and alcohol to oil molar ratio. From direct observations and the modeling of the phase behavior, a better understanding of the supercritical alcohol transesterification process is obtained as well as the confirmation of the phase equilibrium predictions based on the GCA-EOS model.