Liquid-liquid and vapor-liquid equilibrium data for biodiesel reaction-separation systems

This work reports experimental vapor-liquid and liquid-liquid equilibrium data for binary and ternary systems comprised of various mixtures of biodiesel (from soybean oil), methanol, ethanol, glycerol and soybean oil. The binodal curves for biodiesel + methanol + glycerol, biodiesel + ethanol + glycerol, biodiesel + methanol + soybean oil and biodiesel + ethanol + soybean oil systems were obtained at two different temperatures by titration. An Othmer-type ebulliometer was used for vapor-liquid equilibrium measurements at pressures ranging from 14.0 kPa to 92.0 kPa. Binodals curves (LLE) indicated that the temperature range used in this study has no effect on the immiscibility region for the biodiesel + methanol + soybean oil system. By contrast, for the biodiesel + ethanol + soybean oil system, the immiscibility region was larger at the lower temperature. For the vapor-liquid equilibrium data, the results showed that the addition of glycerol to the biodiesel + ethanol binary system does not significantly affect the boiling temperature of the system while with the addition of methanol to the biodiesel + soybean oil system the boiling temperatures of the ternary mixture are reduced. These results can be used to enhance the reaction conversion and the purification processes associated with biodiesel production. (C) 2013 Elsevier Ltd. All rights reserved.