A review of multi-phase equilibrium studies on biodiesel production with supercritical methanol

Biodiesel production with supercritical methanol has several advantages over the conventional process, including being non-catalytic, exhibiting high production efficiency, using a wide range of potential feedstocks, and requiring simple post-processing for the product. The high-pressure phase equilibria of the reactants, intermediates and products in supercritical methanol are the basis for these reactions under supercritical conditions. For an improved understanding of the influence of the phase behaviour of multicomponent mixtures on transesterification, studies on the phase equilibrium of relative reaction systems and transesterification kinetics are needed. The relationship between the phase behaviour and reactions should be classified. Because of the sensitivity of the phase behaviour to temperature and pressure and the difficulty of sampling at high temperature and pressure, the study of the phase equilibrium involving supercritical methanol is just starting. This paper compares the advantages and disadvantages of several biodiesel production methods and provides a summary of multi-phase equilibrium studies on biodiesel production with supercritical methanol.