High-pressure phase equilibrium measurements and thermodynamic modeling for the systems involving CO2, ethyl esters (oleate,stearate, palmitate) and acetone |
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| Affiliation: | 1. Department of Chemical Engineering, Federal University of Paraná (UFPR), Curitiba 82530-990, PR, Brazil;2. Department of Chemistry, Federal University of Paraná (UFPR), Curitiba 81531-990, PR, Brazil;1. Cairo University, Department of Chemical Engineering, Giza, 12613, Egypt;2. American University in Cairo, Department of Petroleum and Energy Engineering, New Cairo, 11835, Egypt;3. Instituto Tecnológico de Aguascalientes, Department of Chemical Engineering, Aguascalientes, 20256, Mexico;1. Department of Petroleum Engineering, Petroleum University of Technology, Ahwaz, Iran;2. Department of Chemical Engineering, Sahand University of Technology, Tabriz, Iran;3. School of Chemical Engineering, Yeungnam University, Gyeungsan, Republic of Korea;4. Southern Cross University, School of Environment, Science and Engineering, Lismore, NSW, Australia;1. Instituto Tecnológico de Aguascalientes, Aguascalientes 20256, Mexico;2. Universidad de Guanajuato, Guanajuato 36050, Mexico;1. MATGAS Research Center, Campus de la UAB, 08193 Bellaterra, Barcelona, Spain;2. Carburos Metálicos/Air Products Group, C/Aragón 300, 08009 Barcelona, Spain |
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| Abstract: | The aim of this work was to study the phase behavior of systems involving carbon dioxide (CO2), fatty acid ethyl esters (ethyl oleate, ethyl stearate and ethyl palmitate) and acetone at high pressures. The phase behavior involving these components is an important step regarding the design and optimization of industrial processes based on supercritical conditions, such as biodiesel production and fatty esters fractionation involving supercritical and/or pressurized solvents. In addition, supercritical CO2 can offer an interesting alternative for glycerol separation in water-free biodiesel purification processes. The binary systems investigated in this work were CO2 + ethyl oleate, and CO2 + ethyl stearate and these were compared with the CO2 + ethyl palmitate system. The ternary CO2 + ethyl palmitate + acetone was also investigated at two different ethyl palmitate to acetone molar ratios of (1:1) and (1:3). The static synthetic method using a variable-volume view cell was employed to obtain the experimental data in the temperature range of 303.15–353.15 K. Vapor–liquid (VL), liquid–liquid (LL) and vapor–liquid–liquid (VLL) phase transitions were observed in these systems. In the binary systems, the solubility increased with the presence of unsaturation and decreased with the number of carbon atoms in the fatty ester chain. Addition of acetone as well as ethanol eliminated the liquid–liquid immiscibility and reduced the pressure transitions, therefore increasing the solubility of the ester in supercritical CO2. The experimental data sets for the binary and ternary systems were successfully modeled using the Peng–Robinson equation of state with the classical van der Waals quadratic mixing rule (PR-vdW2) and Wong-Sandler (PR-WS) mixing rule. Both models showed good performance in the phase equilibrium correlations and in predictions for the binary and ternary systems. |
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| Keywords: | Phase equilibrium Biodiesel Ethyl esters Cubic equation of state High pressure |
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