Vapor–Liquid Equilibria of CO₂ + C1–C5 Alcohols from the Experiment and the COSMO-SAC Model

Abstract

The phase behavior of CO2 + alcohols is crucial for the design and optimization of extraction processes that use these alcohols as cosolvents to increase the solubility of polar solutes in supercritical CO2. In this study, the vapor–liquid equilibria (VLE) of CO2 + 2,2-dimethyl-1-propanol are measured at 333.2 K and 353.2 K with a high pressure view cell technique based on the synthetic method. This completes the literature database for binary VLE of CO2 with low mass alcohols up to pentanols. We further systematically investigate the prediction of all binary CO2 + C1–C5 alcohols mixtures with the COSMO-SAC model. Qualitative predictions are obtained when the COSMO-SAC model is combined with the Peng–Robinson–Stryjek–Vera equation of state through the modified Huron–Vidal first-order or the Wong–Sandler mixing rule.

Vapor–liquid equilibrium measurements of the binary mixtures CO2+acetone and CO2+pentanones

“…1 shows the apparatus for experimentation in this study. This setup was used for VLE measurements in prior work [17,32]. The only modification made for this study was that the surrounding climate chamber was removed because all ketones included in this study are liquid at ambient temperature.…”

“…cosolvents for ScCO 2 are low molecular weight alcohols because they can greatly increase the solubility of polar solutes in ScCO 2 [1,6,13,14,16]. The phase behavior of ScCO 2 + alcohols was systematically investigated by several research groups [17][18][19][20][21][22]. Compared with alcohols, relatively few data were measured for other types of solvents, such as ketones or ethers, which are potential cosolvents for ScCO 2 in some applications [5].…”

“…Temperature and vapor pressure of the mixture were measured with the thermometers Pt1 and Pt2 and the pressure transducer P2. The mole fraction of CO 2 (x CO 2 ) was obtained straightforwardly by the procedure described in previous work [17,32]. The error analysis in terms of x CO 2 was taken from Ref.…”

Multiphase Equilibria Modeling with GCA-EoS. Part II: Carbon Dioxide with the Homologous Series of Alcohols

“…Furthermore, in systems showing partial liquid miscibility or multiphase behavior, that approach can trigger erroneous predictions of the types of phases in equilibrium, besides the wrong saturation points. 19,20 Aware of the consequences of fitting only isothermal or isobaric behavior, some authors considered the overall phase behavior throughout the parametrization of different models. For instance, Polishuk et al 27 proposed the Global Phase Diagram Approach (GPDA) to predict phase equilibria of homologues series.…”

“…A literature review shows that many authors worked hard on the extension of advanced equations of state to model mixtures of CO 2 with n -alcohols. − However, most of the studies only assessed a few alcohols, of either low ,, or high , molecular weight, and isolated projections of the overall phase behavior. As we showed in Part I of this work, fitting isothermal or isobaric equilibrium data, neglecting the binary critical curves and lower and upper critical points may lead to wrong predictions outside the correlated window.…”