(383ba) Unifac Dortmund Correlated Parameters for Liquid-Liquid Equilibrium Prediction Systems of Biodiesel-Related Production Process.

Considering the current environmental goals, the search for renewable and environmentally friendly fuel alternatives is of the most importance to satisfy the world energy demand. Biodiesel produced via the transesterification of vegetable oils is outlined as a suitable alternative due to its potential as a fossil diesel replacement, its renewable nature, and its decrease in pollutant emissions due to the negligible release of aromatic hydrocarbons and sulfates on combustion. In the production of biodiesel, two-phase liquid systems composed by vegetable oils, biodiesel, fatty acids (FAs), glycerol, low molecular weight alcohols, and water are present in most of the process stages, from oil refining, free FAs esterification, transesterification, biodiesel separation, and refining. Thus, accurate modeling and prediction of the liquid-liquid equilibrium (LLE) is of the most importance for process understanding, design, and optimization, to make biodiesel production more competitive. Even though LLE related to biodiesel production has been widely studied in the literature, most of this research only considers a specific set of component mixtures or process conditions or if a larger experimental database is used, the implemented models have limitations to accurately describe all the phenomena. In this work, a set of group interaction parameters (GIP) for the UNIFAC Dortmund model that describes the LLE for all the systems involved in biodiesel production was correlated and validated. An experimental database consisting of 1414 tie lines from 97 literature references was constructed and used to correlate the UNIFAC Dortmund GIP. These parameters describe the LLE involved in the correlation process with an accurate fit. The UNIFAC Dortmund GIP describes the LLE for systems of biodiesel-related production processes with a better fit than the UNIFAC GIP.