Capabilities and Limitations of an Association Theory for Chemicals in Liquid or Supercritical Solvents

The cubic-plus-association (CPA) model is an equation of state (EoS) that combines the Soave–Redlich–Kwong (SRK) equation with the association term from Wertheim’s theory as used in statistical associating fluid theory (SAFT). In the form used here, the CPA EoS does not include separate terms for the polar and quadrupolar contributions. The capabilities and limitations of the CPA model when it is applied to mixtures with nonpolar and polar chemicals, as well as associating (hydrogen-bonding) compounds are illustrated. Three case studies are considered, all of which are of industrial relevance. The capabilities of the model are illustrated in the first two case studies: the phase behavior of mixtures used in the oxidation of 2-octanol in supercritical CO2 and the investigation of systems containing acetone, methanol, water, chloroform, and methyl acetate. In each case, both correlations of vapor–liquid and liquid–liquid equilibria for binary systems and predictions for multicomponent mixtures are presented. Finally, the limitations of the CPA model are illustrated in the last case study, which focuses on the modeling of mixtures containing aromatic acids, such as benzoic and terephthalic acid. We also include a detailed discussion of the capabilities and limitations of the model in context and related to previous investigations. Finally, results are compared to observations from studies with other association models

VAPOR–LIQUID–LIQUID EQUILIBRIUM MEASUREMENTS AND MODELING OF METHANETHIOL OR ETHANETHIOL OR OR 1-BUTANETHIOL IN METHANE + WATER TERNARY SYSTEMS AT 303, 335, AND 365 K AND PRESSURE UP TO 9 MPA

International audienceSubmit your abstract below (400 words): Abstract: New vapor−liquid−liquid equilibrium (VLLE) data for methanethiol + methane + water, ethanethiol + methane + water, 1-propanethiol + methane+ water, and 1-butanethiol + methane + water ternary systems have been measured at three temperatures (303, 335, and 365 K) and pressures up to 9 MPa. A " static-analytic " method was used for performing all the measurements. The total system pressure was maintained by CH 4. The objective of this work is to provide experimental VLLE data with thermodynamic modeling for mixtures of mercaptans (thiols) with other natural gas contents at its crude form, for which no data are available in the open literature. Such data will help the industrial modeling of processes relevant to reduction of sulfur emissions. The Cubic-Plus-Association (CPA) equation of state was applied to describe the phase behavior of the investigated systems. It is shown that the CPA EoS satisfactorily describes the solubilities of mercaptans (thiols) in all phases. It is observed from the experimental data that the solubility of CH 4 in the aqueous and organic phases increases with an increase of the total system pressure and decreases with an increase of the temperature. However, the solubility of CH 3 SH in the aqueous and organic phases decreases slightly with an increase of the total system pressure and increases significantly with an increase of the temperature. The new VLLE data of ternary system were compared with predictions of the cubic-plus-association equation of state. The model tends to under predict the concentration of CH3SH in all phases, particularly the vapor phase. However, the model underestimates the water content of the vapor phase, especially at low pressures and at the highest investigated temperature, i.e., at 365 K. Only the ethanethiol + methane + water system showed significant cross-association effects. Furthermore, no cross association (solvation) was found to be significant in 1-propanethiol + methane + water and 1-butanethiol + methane +water ternary systems. Highlight 1: New vapor−liquid−liquid equilibrium (VLLE) data for methanethiol + methane + water, ethanethiol + methane + water, 1-propanethiol + methane+ water, and 1-butanethiol + methane + water ternary systems have been measured at three temperatures (303, 335, and 365 K) and pressures up to 9 MPa

Phase Equilibria of Three Binary Mixtures: Methanethiol + Methane, Methanethiol + Nitrogen, and Methanethiol + Carbon Dioxide

International audienceNew vapor-liquid equilibrium (VLE) data for methanethiol (MM) + methane (CH 4), methanethiol (MM) + nitrogen (N 2), and methanethiol (MM) + carbon dioxide (CO 2) is reported for temperatures of (304, 334, and 364) K in the pressure range (1 to 8) MPa. A "static- analytic" method was used for performing the measurements. The objective is to provide experimental VLE data for methanethiol with other natural gas contents at its crude form, for which no data are available in the open literature. The new VLE data for the aforementioned systems have been modeled successfully with the cubic-plus-association equation of state (CPA EoS)

Phase Equilibrium Measurements and Modeling of 1-Propanethiol+1-Butanethiol + CH₄ in Methane Ternary System at 303, 336, and 368 K and Pressure Up to 9 MPa

International audienceNew vapor-liquid equilibrium (VLE) data for 1-propanethiol + 1-butanethiol + CH4 ternary system is reported. Measurements were performed at three different temperatures (303, 336 and 368 K), while the pressure was ranged from1 to 9 MPa. The total system pressure was maintained by CH4. The inlet mole fraction of 1-propanethiol (x = 5.43 10-1) and 1n-butanethiol (x = 4.56 10-1) in the liquid phase were same in all experiments. A static analytic method was used for performing phase equilibrium measurements. The new VLE data have been modeled successfully with Cubic-Plus-Association (CPA) EoS

Vapor–Liquid–Liquid Equilibrium Measurements and Modeling of the Methanethiol + Methane + Water Ternary System at 304, 334, and 364 K

International audienceNew vapor-liquid-liquid equilibrium (VLLE) data for methanethiol (CH 3SH) + methane (CH 4) + water (H 2O) have been obtained at three temperatures (304, 334, and 364 K) and pressures up to 9 MPa. A "static-analytical" method was used to perform all of the measurements. The objective was to provide experimental VLLE data for CH 3SH with other natural gas contents at its crude form for which limited or no data are available in the open literature. Such kinds of data are required for the industrial modeling of sulfur emissions. It is observed from the experimental data that the solubility of CH 4 in the aqueous and organic phases increases with an increase of the total system pressure and decreases with an increase of the temperature. However, the solubility of CH 3SH in the aqueous and organic phases decreases slightly with an increase of the total system pressure and increases significantly with an increase of the temperature. The new VLLE data of this ternary system were compared with predictions of the cubic-plus-association equation of state. The model tends to underpredict the concentration of CH 3SH in all phases, particularly the vapor phase