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In recent years, the dramatic increase of greenhouse gases concentration in atmosphere, especially of carbon dioxide, determined many researchers to investigate new mitigation options. Thermodynamic studies play an important role in the development of new technologies for reducing the carbon levels. In this context, our group investigated the phase behavior (vapor–liquid equilibrium (VLE), vapor–liquid–liquid equilibrium (VLLE), liquid–liquid equilibrium (LLE), upper critical endpoints (UCEPs), critical curves) of binary and ternary systems containing organic substances with different functional groups to determine their ability to dissolve carbon dioxide. This study presents our results for the phase behavior of carbon dioxide + n-butanol structural isomers binary systems at high-pressures. Liquid–vapor critical curves are measured for carbon dioxide + isobutanol and carbon dioxide + tert-butanol binary systems at pressures up to 147.3 bar, as only few scattered critical points are available in the literature. New isothermal vapor–liquid equilibrium data are also reported at 363.15 and 373.15 K. New VLE data at higher temperature are necessary, as only another group reported some data for the carbon dioxide + isobutanol system, but with high errors. Phase behavior experiments were performed in a high-pressure two opposite sapphire windows cell with variable volume, using a static-analytical method with phases sampling by rapid online sample injectors (ROLSI) coupled to a gas chromatograph (GC) for phases analysis. The measurement results of this study are compared with the literature data when available. The new and all available literature data for the carbon dioxide + isobutanol and carbon dioxide + tert-butanol binary systems are successfully modeled with three cubic equations of state, namely, General Equation of State (GEOS), Soave–Redlich–Kwong (SRK), and Peng–Robinson (PR), coupled with classical van der Waals mixing rules (two-parameter conventional mixing rules, 2PCMR), using a predictive method. [ABSTRACT FROM AUTHOR]

The ability of different thermodynamic models to predict the phase behaviour of carbon dioxide (1) + 1,2-dimethoxyethane (2) binary system is tested. The model chosen is the General Equation of State (GEOS) coupled with classical van der Waals mixing rules (two-parameter conventional mixing rule, 2PCMR). Comparisons were made with the GEOS3C, Soave-Redlich-Kwong (SRK), and Peng-Robinson (PR) cubic equations of state (EoS) too. A single set of binary parameters for each model was used to predict correctly the global phase behaviour of the system. [ABSTRACT FROM AUTHOR]

Vapor–liquid (VLE) data for the carbon dioxide + 1,2-dimethoxyethane binary system at 313.15, 323.15, 333.15, and 343.15 K up to 10.69 MPa and the critical curve are reported for the first time. Phase behavior measurements were made in a high-pressure visual cell with variable volume, using a static-analytical method with phases sampling by rapid online sample injectors (ROLSI) coupled to a gas chromatograph (GC) for analysis. The new measured data for carbon dioxide +1,2-dimethoxyethane system were modeled with two cubic equations of state (EoS), namely the Peng–Robinson (PR), and Soave–Redlich–Kwong (SRK), coupled with both classical van der Waals (two-parameter conventional mixing rule, 2PCMR) and Gibbs excess energy (G E ) mixing rules (HV-residual UNIQUAC, MHV1, MHV2, COMB1, COMB2). [ABSTRACT FROM AUTHOR]

The purpose of this paper is to compare three thermodynamicmodels to correlate the phase behavior of the highly polar system:carbon dioxide heptanol. These three models rely either on thePeng–Robinson (PR) or on the Soave–Redlich–Kwong(SRK) equations of state and are all coupled with classical van derWaals one-fluid mixing rules. For the two first models, noted SRK/2PCMRand PR/2PCMR, where 2PCMR means two-parameter conventionalmixing rule, a single set of temperature-independent binaryparameters (kijand lij) was considered. The thirdmodel is the well-established PPR78 model also based on the PR equationof state (1978 version). In such a model, lij= 0 but the second binary interaction parameter(kij) is temperature-dependentand predicted by a group-contribution method. All available literaturedata in a wide range of pressures and temperatures and the globalphase equilibrium diagram of the system were calculated with the threeaforementionedmodels. Although the models used are simple, they are able to representreasonably well the complex phase behavior of the system studied inthis work. [ABSTRACT FROM AUTHOR]

Abstract: Vapor–liquid–equilibria (VLE) and vapor–liquid–liquid equilibria (VLLE) data for the carbon dioxide+1-nonanol system were measured at 303.15, 308.15, 313.15, 333.15, and 353.15K. Phase behavior measurements were made in a high-pressure visual cell with variable volume, based on the static-analytic method. The pressure range under investigation was between 1.15 and 103.3bar. The Soave–Redlich–Kwong (SRK) equation of state (EOS) coupled with both classical van der Waals and a Gibbs excess energy (G E ) mixing rules was used in semi-predictive approaches, in order to represent the complex phase behavior (critical curve, liquid–liquid–vapor (LLV) line, isothermal VLE, LLE, and VLLE) of the system. The topology of phase behavior is correctly predicted. [ABSTRACT FROM AUTHOR]

Vapor−liquid (VLE), liquid−liquid (LLE), and vapor−liquid−liquid equilibria (VLLE) data for the carbon dioxide + n-pentadecane system at (293.15, 303.15, 313.15, 333.15, and 353.15) K up to 17.50 MPa and phase compositions of the two liquid phases and vapor phase as a function of temperature along the liquid−liquid−vapor (LLV) line are reported. The experimental method used in this work was a static-analytical method with liquid and vapor phase sampling. The new experimental results are discussed and compared with available literature data. Measured data and literature data for the carbon dioxide + n-pentadecane system were modeled with the Soave−Redlich−Kwong (SRK) EoS using classical van der Waals (two-parameter conventional mixing rule, 2PCMR) mixing rules. A single set of interaction parameters was used to predict the complex phase behavior in the binary mixture carbon dioxide + n-pentadecane. [ABSTRACT FROM AUTHOR]

Vapor−liquid equilibria (VLE) data for the carbon dioxide + 2-butanol system at (298.15, 303.15, 308.15, 313.15, and 318.15) K up to 81.5 bar are reported. The experimental method used in this work was a static-analytical method with liquid and vapor phase sampling. The new experimental results are discussed and compared with available literature data. Measured VLE data and literature data for the carbon dioxide + 2-butanol system were modeled with a general cubic equation of state (GEOS), Peng−Robinson (PR) equation of state (EoS), and Soave−Redlich−Kwong (SRK) EoS using classical van der Waals (two-parameter conventional mixing rule, 2PCMR) mixing rules. A single set of interaction parameters for each equation of state, representing exactly the experimental critical pressure maximum (CPM) and the experimental temperature of the upper critical end point (UCEP), was used to calculate the phase behavior in the binary mixture carbon dioxide + 2-butanol in a wide range of temperatures [(278.21 to 512.3) K]. The GEOS equation is more reliable for predicting the critical curve and the bubble-point lines, and it is less exact for predicting the gas phase composition at higher temperatures. [ABSTRACT FROM AUTHOR]

Abstract: Vapor–liquid equilibria (VLE) data for the carbon dioxide+ethanol system at 293.15, 303.15, 313.15, 333.15, and 353.15K up to 11.08MPa are reported. The experimental method used in this work was a static-analytical method with liquid and vapor phase sampling. The new experimental results are discussed and compared with available literature data. Measured VLE data and literature data for carbon dioxide+ethanol system were modeled with a general cubic equation of state (GEOS) using classical van der Waals (two parameters conventional mixing rule—2PCMR) mixing rules. A single set of interaction parameters was used to calculate the global phase behavior in the binary mixture carbon dioxide+ethanol in a wide range of temperatures (283.3–453.15K). [Copyright &y& Elsevier]

New isothermal vapor–liquid equilibrium (VLE) data for the carbon dioxide + 1,4-dioxane system are reported at four temperatures (323.15, 333.15, 343.15, and 353.15) K and pressures up to 122.7 bar. The critical curve was also measured up to 158.8 bar and 420.15 K. Phase behavior measurements were performed in a high-pressure windowed cell with variable volume, using a static-analytical method with phases sampling by rapid online sample injectors (ROLSI) coupled to a gas chromatograph (GC) for analysis. The experimental results of this study are compared with the scarce available literature data. The new and all available literature data for the carbon dioxide + 1,4-dioxane binary system are modelled with the cubic Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR) equations of state (EoS) with classical van der Waals mixing rules (two-parameter conventional mixing rules, 2PCMR). The modeling showed that SRK and PR models can accurately predict the phase behavior of the system studied. [ABSTRACT FROM AUTHOR]

In recent years we have focused our efforts on investigating various binary mixtures containing carbon dioxide to find the best candidate for CO2 capture and, therefore, for applications in the field of CCS and CCUS technologies. Continuing this project, the present study investigates the phase behavior of three binary systems containing carbon dioxide and different oxygenated compounds. Two thermodynamic models are examined for their ability to predict the phase behavior of these systems. The selected models are the well-known Peng–Robinson (PR) equation of state and the General Equation of State (GEOS), which is a generalization for all cubic equations of state with two, three, and four parameters, coupled with classical van der Waals mixing rules (two-parameter conventional mixing rule, 2PCMR). The carbon dioxide + ethyl acetate, carbon dioxide + 1,4-dioxane, and carbon dioxide + 1,2-dimethoxyethane binary systems were analyzed based on GEOS and PR equation of state models. The modeling approach is entirely predictive. Previously, it was proved that this approach was successful for members of the same homologous series. Unique sets of binary interaction parameters for each equation of state, determined for the carbon dioxide + 2-butanol binary model system, based on k12–l12 method, were used to examine the three systems. It was shown that the models predict that CO2 solubility in the three substances increases globally in the order 1,4-dioxane, 1,2-dimethoxyethane, and ethyl acetate. CO2 solubility in 1,2-dimethoxyethane, 1.4-dioxane, and ethyl acetate reduces with increasing temperature for the same pressure, and increases with lowering temperature for the same pressure, indicating a physical dissolving process of CO2 in all three substances. However, CO2 solubility for the carbon dioxide + ether systems (1,4-dioxane, 1,2-dimethoxyethane) is better at low temperatures and pressures, and decreases with increasing pressures, leading to higher critical points for the mixtures. By contrast, the solubility of ethyl acetate in carbon dioxide is less dependent on temperatures and pressures, and the mixture has lower pressures critical points. In other words, the ethers offer better solubilization at low pressures; however, the ester has better overall miscibility in terms of lower critical pressures. Among the binary systems investigated, the 1,2-dimethoxyethane is the best solvent for CO2 absorption. [ABSTRACT FROM AUTHOR]

New isothermal vapor–liquid equilibrium (VLE) data for the carbon dioxide + 2-octanol system are measured at five temperatures between 298.15 and 333.15 K and pressures up to 103 bar. The experimental method used is the static-analytical one with phases sampling. The new experimental data obtained in this study are compared with all available literature data and discussed. The new and all available literature data for the carbon dioxide + 2-octanol binary system are modeled with three cubic equations of state, namely the G eneral E quation o f S tate (GEOS), Soave–Redlich–Kwong (SRK), and Peng–Robinson (PR) equations of state (EoS) with classical van der Waals mixing rules. The phase behavior of the carbon dioxide + 2-octanol binary system (critical curves, the three-phase equilibrium curves, isothermal VLE, and vapor–liquid–liquid equilibria) was modeled using a semi-predictive methodology. The results of the calculations are compared to both the new data reported in this work and all available literature data. The results show a satisfactory level of agreement between the models and the experimental data. [ABSTRACT FROM AUTHOR]

New isothermal vapor-liquid equilibrium (VLE) and vapor-liquid-liquid equilibrium data for the carbon dioxide + 1-octanol system are reported at several temperatures, 303.15, 310.15, 315.15, 323.15, and 333.15 K, and pressures up to 145 bar. A static-analytical method with phase sampling was used. The experimental results of this study are compared with literature data when available and discussed. The new and all available literature data for the carbon dioxide +1-octanol binary system are modeled with the cubic general equation of state and Peng-Robinson equations of state (EoS) with classical van der Waals mixing rules. The aforementioned EoS's were used to model the phase behavior of the carbon dioxide + 1-octanol binary system (critical curves, the three-phase equilibrium curve, isothermal VLE, and vapor-liquid-liquid equilibria), using a semipredictive approach. The results of the calculations are compared to the new data reported in this work and to all available literature data. The results show a satisfactory level of agreement between the models and the experimental data. [ABSTRACT FROM AUTHOR]

The phase behavior of the branched alkane 2,4-dimethyl pentane (2,4-DMP) and carbon dioxide (CO 2) binary mixture that has no published data, to the best of our knowledge, was studied. The liquid–vapor critical line was determined up to 121.4 bar and 422.35 K, as well as vapor–liquid equilibrium (VLE) data at different constant temperatures (323.15, 343.15, 363.15, and 383.15) K and pressures between (10.4 and 120.4) bar. Phase behavior investigation was carried out in a high-pressures (HP) cell fitted with a pair of sapphire windows, one acting as a piston, hence volume up to 60 cm3, utilizing a static-analytical approach with phases sampling by the so called ROLSI valves (rapid online sample injectors) connected to a gas chromatograph (GC) for composition determination. The isothermal and critical data points for the carbon dioxide + 2,4-dimethylpentane binary mixture were modeled with the cubic equations of state (EoSs), i.e., Soave–Redlich–Kwong (SRK), Peng–Robinson (PR), and General Equation of State (GEOS), in combination with van der Waals mixing rules (one- and two-parameter conventional mixing rules, 1PCMR and 2PCMR). The calculations demonstrated that the selected models are capable of correctly reproducing the phase behavior of the mixture under study. [Display omitted] • Isothermal VLE data are for the first time reported for CO 2 + 2,4-dimethylpentane binary system at high-pressures. • LV critical curve (P – T – X 1) is also measured at pressures up to 121.4 bar and 422.35 K. • GEOS, PR, and SRK EoSs with classical van der Waals mixing rules successfully modeled the system. [ABSTRACT FROM AUTHOR]

Isothermal (vapour + liquid) equilibrium (VLE) data for the binary systems (carbon dioxide + cyclopentane) and (carbon dioxide + cyclohexane) were determined using a (static + analytical) method with phases sampling by rapid online sample injectors (ROLSI) coupled to a gas chromatograph (GC) for analysis. The VLE behaviour for these systems was also analysed based on the PR and RKPR equations of state (EoS) and different available data from the literature, both critical and subcritical. It is clearly shown how CO 2 is more soluble and miscible with normal alkanes than with the corresponding cycloalkanes. Predictions based on the general correlation of available data in wide ranges of conditions suggest the appearance of double retrograde behaviour at least for (CO 2 + cyclohexane) mixtures with very low contents of the hydrocarbon in CO 2 , being this phenomenon very much related to asymmetry of the system. The existence of this phenomenon has not been experimentally confirmed yet for these systems and should be explored. [ABSTRACT FROM AUTHOR]