Measurements of Liquid−Liquid Equilibria for a Methanol + Glycerol + Methyl Oleate System and Prediction Using Group Contribution Statistical Associating Fluid Theory

Abstract

A good understanding and prediction of the phase equilibrium of the fatty acid methyl ester (FAME) + glycerol + methanol ternary system is needed to design and optimize the separation unit of the biodiesel production process. In this work, new experimental vapor−liquid−liquid data on the ternary system have been measured at temperatures between 333.15 and 473.15 K. In addition, new data have been gathered on the methanol + glycerol [vapor−liquid equilibrium (VLE)] and methanol + methyl oleate (VLE and liquid−liquid equilibrium) binary systems. A group contribution method combined with a statistical associating fluid theory equation of state (GC-PPC-SAFT) proposed earlier by our group (Group contribution method with SAFT EOS applied to vapor liquid equilibria of various hydrocarbons series Tamouza S. Passarello J.-P. Tobaly P. de Hemptinne J.-C. Tamouza S. Passarello J.-P. Tobaly P. de Hemptinne J.-C. Fluid Phase Equilib.20042222236776) and recently extended to predict VLE of heavy esters and their mixtures (Predicting VLE of heavy esters and their mixtures using GC-SAFT Nguyen Huynh D. Falaix A. Passarello J.-P. Tobaly P. de Hemptinne J.-C. Nguyen Huynh D. Falaix A. Passarello J.-P. Tobaly P. de Hemptinne J.-C. Fluid Phase Equilib.2008264184200) is here applied to model vapor liquid−liquid equilibria of methanol + glycerol + methyl oleate. The SAFT parameters for the glycerol pure component have been regressed using two association schemes (4C and 3X2B). The dispersive binary interaction parameters kij have been regressed on the binary systems. The group contribution scheme was used for predicting the ester properties.

Extension of the validation method for vapor–liquid equilibrium data to systems with nonvolatile components

“…Table shows the quantitative results obtained when the test is applied to a group of 70 published nv‐VLE data series . The results show a rejection ratio (rejected/analyzed systems) of 40% for a κ ψ = 3, see Equation , although this value decreases to 12% when κ ψ = 5.…”

“…Figure a shows the iso‐101.32 kPa VLE data published by Barreau et al for the binary methanol(1)+glycerol(2) in the composition interval x 1 ∈[0.25–1], for which the assumption of nonvolatility is acceptable. The model obtained for this system, using all the experimental data (version‐1 of the modeling), reproduces satisfactorily the behavior in the diagram ( x 1 , T ), Figure a, and also the values of γ 1 , Figure b.…”

“…Results obtained when applying the test to methanol(1)+glycerol(2) at 101.32 kPa, from Barreau et al (●) Experimental values, (♦) values and results () with the version‐1 of the model, and () values and results () with the version‐2 of the model. (a) Plot ( T , x 1 ), (b) plot ( γ i , x 1 ), (c) plot (, x 1 ) [Color figure can be viewed at wileyonlinelibrary.com]…”

Liquid-Liquid Equilibria for Systems Containing Fatty Acid Ethyl Esters, Ethanol and Glycerol at 333.15 and 343.15 K: Experimental Data, Thermodynamic and Artificial Neural Network Modeling

“…Some are based on empirical equations for the activity coefficients, such as Margules and Van Laar; others such as Wilson (1964), NRTL (Renon and Prausnitz, 1968) and UNIQUAC (Abrams and Prausnitz, 1976), use the local composition concept, and finally ASOG (Kojima and Tochigi, 1979) and UNIFAC (Fredenslund et al, 1975), use the group contribution concept. Other approaches with a sound theoretical background are the association equations of state (EoS) such as the Statistical Associating Fluid Theory (SAFTEoS) (Barreau et al, 2010), and the Cubic-Plus-Association (CPA EoS) (Follegatti-Romero et al, 2012a, 2012bOliveira et al, 2010;Oliveira et al, 2009;Oliveira et al, 2008;Oliveira et al, 2007). Although there are several works using artificial neural networks to predict vapor-liquid (Nguyen et al, 2007;Urata et al, 2002) and liquid-liquid (Ghanadzadeh et al, 2012;Gebreyohannes et al, 2013) equilibrium data, no prior investigation for systems related to ethylic biodiesel production and purification was found in the open literature.…”

Experimental Data, Thermodynamic Modeling and Sensitivity Analyses for the Purification Steps of Ethyl Biodiesel From Fodder Radish Oil Production

“…Pisarello et al (2010) have studied LLE in the reacting systems involved in the acid catalysis for biodiesel production evaluating the influence of the composition on the phase splitting. Other research groups, studying LLE in the purification steps, have evaluated the LLE of systems containing alcohol, biodiesel or alkyl esters, glycerol or water (Liu et al, 2008;Beneti et al, 2010), modeled them using thermodynamic models with association parameters (Barreau et al, 2010;Oliveira et al, 2011;Andreatta et al, 2008) or using classical thermodynamic molecular models (Mesquita et al, 2011;Casas et al, 2014). In addition, some works compared molecular models with predictive models in relation to description of the LLE for this type of system (Lee et al, 2010).…”