Measurement and thermodynamic modeling of solid–liquid–gas equilibrium of some organic compounds in the presence of CO2 (original) (raw)
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The Journal of Supercritical Fluids, 2017
Six predictive approaches based on the Peng-Robinson (PR) equation of state (EOS), conductor-like screening model segment activity coefficient (COSMO-SAC), and mixing rules were applied to model solid-liquid-gas equilibrium for 21 binary mixtures of CO2 and an organic compound. The accuracy of these approaches in predicting equilibrium temperatures at given pressures (635 experimental data with T = 220~413.97 K and P = 0.05~48.35 MPa), liquid phase compositions, and liquid molar volumes was examined and compared to provide an overview on their performance. The recently developed PR+COSMO-SAC EOS was found to be most accurate, with deviations of 6.25 K in temperature, 0.071 in liquid mole fraction, and 21% in liquid molar volume. The performance of these models can be very different for the solid containing different functional groups. Nevertheless, the PR+COSMO-SAC EOS could provide useful a priori predictions with only input of experimental heat of fusion and melting temperature of the solid.
Fluid Phase Equilibria, 2007
High pressure vapor-liquid equilibrium data for binary systems of carbon dioxide with naphthalene and benzoic acid were measured at three different temperatures for each system. Experimental temperatures and pressures ranged from 373 to 458 K and 0 to 22 MPa, respectively. Dew points were also measured for naphthalene in the CO 2 rich region. The data measured provides valuable solubility information and is used to derive gas-solvent group interaction parameters for the predictive Soave-Redlich-Kwong equation of state.
Industrial & Engineering Chemistry Research, 2012
The phase equilibria of binary CO 2 + n-alkane mixtures have been studied by an important number of authors, both experimentally and using different types of thermodynamic models. Modeling studies of the phase behavior of such highly nonideal systems have generally achieved only partially accurate results in the correlation of phase equilibrium data when considering wide ranges of temperature, pressure, and n-alkane molecular weight. In this study, a predictive correlation for the phase behavior of CO 2 + n-alkane systems, based on a three-parameter cubic equation of state (EOS), that is, the RK-PR EOS, coupled to cubic mixing rules (CMRs), is developed and tested. CMRs have been shown to be capable of an accurate correlation of the phase equilibria asymmetric CO 2 + n-alkane binary systems, in wide ranges of temperature and pressure, when using system-specific interaction parameters. For developing the predictive correlation a critical review of published experimental data for the series was carried out, covering a total of about 100 references. An important degree of inaccuracy or scatter is often found when comparing data sets from different laboratories, specially for the more asymmetric systems (CO 2 + a long chain n-alkane). Tables of references covering CO 2 + n-alkane systems from C1 to C36 are presented for different types of experimental data, including critical end points (CEPs), critical points, liquid−liquid−vapor (LLV) equilibrium, and isobaric (Txy), isothermal (Pxy), and isoplethic (PT) two-phase equilibrium data sets. Examples of disagreement between different sets of data are presented and discussed. In some cases, a decision concerning the identification of the set that should be regarded as the most reliable, can be based on the experimental method employed, on the purity of the n-alkane, and on the observation of other data for conditions, and/or systems in the series, which are close to those of the data set under scrutiny. Nevertheless, the availability of such information is not enough, in other cases, to assess the quality of a given data set, where we have either different data sets in disagreement or a unique set, for which we are in doubt about its accuracy. In such situation, a predictive correlation for the whole series of binary systems is helpful to make a decision on the possible level of reliability of a given phase equilibrium data set. The present study is useful both to make decisions on conflicts between contradictory phase equilibrium data sets and to predict the phase equilibria of binary systems that have no experimental information available in the literature.
Journal of Chemical and Petroleum Engineering, 2020
The accurate description of the phase equilibria of CO2 and n-Alkane multicomponent mixtures over a wide range of temperature, pressure, and n-Alkane molecular weight, requires models that are both consistent and mathematically flexible for such highly non-ideal systems. In this study, a predictive correlation was proposed for the vapor-liquid equilibrium data (VLE) of CO2 and n-Alkane ternary systems, based on the Peng-Robinson equation of state (PR EOS), coupled with cubic mixing rules (CMRs). The ternary interaction parameters (TIP) correlation is developed using binary VLE data and tested for CO2 + n-Alkane + n-Alkane ternary systems. For this purpose, binary VLE data of CO2 + n-Alkane and n-Alkane + n-Alkane systems for n-Alkane from C3 to C24, covering a total of about 70 references, used to correlate TIP in the ranges of 0.5-31 MPa and 230-663 K. Two temperature-dependent TIP correlations, based on acentric factor ratio, have been tuned with more than 2000 data points of the CO2 + n-Alkane and the n-Alkane + n-Alkane binary systems with AARD of 3.13% and 6.71%, respectively. The generalized predictive correlation was proposed based on the proper three-body interaction contributions and successfully tested for VLE data of the CO2 + n-Alkane + n-Alkane ternary systems.
The Journal of Chemical Thermodynamics, 2013
This work reports phase equilibrium measurements for the binary {CO 2 (1) + ethyl palmitate(2)} and ternary {CO 2 (1) + ethyl palmitate(2) + ethanol(3)} systems at high pressures. There is currently great interest in biodiesel production processes involving supercritical and/or pressurized solvents, such as non-catalytic supercritical biodiesel production and enzyme-catalysed biodiesel production. Also, supercritical CO 2 can offer an interesting alternative for glycerol separation in the biodiesel purification step in a water-free process. In this context, the main goal of this work was to investigate the phase behaviour of binary and ternary systems involving CO 2 , a pure constituent of biodiesel ethyl palmitate and ethanol. Experiments were carried out in a high-pressure variable-volume view cell with operating temperatures ranging from (303.15 to 353.15) K and pressures up to 21 MPa. The CO 2 mole fraction ranged from 0.5033 to 0.9913 for the binary {CO 2 (1) + ethyl palmitate(2)} system and from 0.4436 to 0.9712 for ternary system {CO 2 (1) + ethyl palmitate(2) + ethanol(3)} system with ethyl ester to ethanol molar ratios of (1:6), (1:3), and (1:1). For the systems investigated, vapour-liquid (VL), liquid-liquid (LL) and vapourliquid-liquid (VLL) phase transitions were observed. The experimental data sets were successfully modeled using the Peng-Robinson equation of state with the classical van der Waals quadratic (PR-vdW2) and Wong-Sandler (PR-WS) mixing rules. The PR-WS showed good performance in the prediction of the phase transition for the ternary systems based on the binary system data.
Phase equilibria of mixtures containing CO2 and organic acids using the UMR-PRU model
The Journal of Supercritical Fluids, 2011
The UMR-PRU model, which has been successfully tested in the past to the predictions of different type of phase equilibrium and thermodynamic properties in binary and multicomponent systems, is applied in this work to phase equilibria in mixtures containing CO 2 and organic acids. New interaction parameters are determined by fitting only binary vapor-liquid equilibrium data and then they are used to predict the vapor-liquid, solid-gas and solid-liquid-gas equilibria in CO 2 /organic acid systems. Furthermore, the UMR-PRU model with the newly derived interaction parameters is applied to the prediction of the phase equilibrium in ternary mixtures consisting of CO 2 , organic acids and water. Satisfactory results are obtained in all cases.
At present, the accurate evaluation of the thermo-physical behaviour of multicomponent fluids represents a crucial element for studying and simulating low CO2 emission energy conversion technologies. In order to extend the range of application of the available thermodynamic models, an intense experimental research activity has been performed in recent years. The main purpose of this paper is to describe the experimental and modelling procedures applied by the authors to measure and to analyse data extracted from the Vapour-Liquid Equilibrium apparatus recently installed at LEAP laboratory. This test rig allows the characterization of mixture phase equilibrium properties on the basis of the static-analytical method, within the pressure and temperature ranges of 0 -20 MPa and -60 -200 °C. Finally, the paper reports the most relevant features and the main guidelines for the instruments calibration procedures.
Journal of Supercritical Fluids - J SUPERCRIT FLUID, 2011
Knowledge regarding the high pressure phase behavior of CO2 mixtures is of primary importance for designing, operating and optimizing many industrial processes, such as supercritical fluid extraction for pharmaceutical, food and biodiesel industries and oil recovery enhancement through CO2 flooding.In the present work, it is investigated how the CPA EoS (Cubic-Plus-Association equation of state) can be used for an adequate description of the VLE of an extensive series of CO2 binary systems containing n-alkanes, n-alcohols, esters and n-acids, in a broad range of temperatures and pressures. These families constitute a series of non-self associating, associating and cross-associating components whose potential associative interactions with CO2 are evaluated here.A detailed investigation regarding the differing behavior of CO2 depending on the nature of the second component and how the CPA EoS can best describe them is presented here, namely explicitly considering the CO2 association a...