Phase Equilibrium Data For Systems Research Articles

High-pressure phase equilibrium data for systems involving carbon dioxide, globalide, ε-caprolactone, poly(globalide-co-ε-caprolactone) and dichloromethane

High-pressure phase equilibrium data for systems involving carbon dioxide, globalide, ε-caprolactone, poly(globalide-co-ε-caprolactone) and dichloromethane

Phase equilibrium data for clathrate hydrates formed in the systems of urea + (methane or carbon dioxide) + water

Subsea methane hydrates are expected as a potential natural gas resource. To develop gas production methods for the subsea methane hydrates, flow assurance technologies are necessary. Urea is one of the environmentally-friendly thermodynamic hydrate inhibitors (THIs) which is expected to be applicable for subsea methane hydrate systems. To evaluate its performance as a THI, a set of phase equilibrium data are necessary. In this study, we report phase equilibrium data for systems of urea + methane + water and urea + carbon dioxide + water in the range of aqueous compositions of urea up to its solubility limits. The present data for urea + methane + water ranged in pressures from 5 to 13 MPa and in urea mass fractions from 0.05 to 0.5. The comparison with the literature found that the inhibition effect of urea is a few kelvin weaker than that of methanol in the present measurement range. With the dense urea solutions, the system reached four phase equilibrium, i.e., solid urea–aqueous solution–gas–hydrate. At 13 MPa, approximately 13 K of inhibition temperature was obtained with 0.500 of feed mass fraction where solid urea was precipitated from the aqueous phase. In the urea + carbon dioxide + water systems, urea also worked as a THI. The maximum inhibition temperature was approximately 10 K with 0.400 of urea mass feed fraction at the four phase equilibrium. Based on the present equilibrium data and seafloor conditions of the subsea methane hydrates, it was found that urea can be used for the both systems of the methane gas production and the hydrate based carbon capture and storage.

Experimental high-pressure phase equilibria of carbon dioxide/n-alkanes mixtures and model-parameters for solid-phase obtained from DSC thermograms

We provide high-pressure experimental phase equilibrium data for systems containing mixtures formed by CO2 and mixtures of n-alkanes (n-C10H22/n-C20H42, n-C10H22/n-C24H50, n-C10H22/n-C20H42/n-C24H50) with CO2 weight fractions of 55%, 65% and 75%, temperature ranging from 273 K to 363 K and pressures up to 55 MPa. The measured equilibrium data include vapor-liquid (VL), solid-liquid (SL), and solid-liquid-vapor (SVL) phase transitions. Additionally, calorimetric (DSC) measurements were carried out at atmospheric pressure for mixtures of n-C10H22 (solvent), n-C16H34, n-C20H42, and n-C24H50, with the temperature range from 253 K to 333 K. To describe the phase-equilibrium diagrams, the solid phases were modeling using the multiple-solid solutions approach, which employs the modified UNIQUAC equation to calculate the activity coefficients. The UNIQUAC-energy interaction parameter λij and the Poynting correction factor were used to take into account the n-alkane/n-alkane interactions and pressure effect in the solid-liquid equilibria. We used the Peng-Robinson equation of state to describe the liquid and vapor phases. The phase equilibrium predictive calculations were in good agreement with the measured phase-transition data considering the experimental uncertainty.

High-pressure phase equilibrium data for systems containing carbon dioxide, ω-pentadecalactone, chloroform and water

Abstract Experimental phase equilibrium data for the pseudobinary system involving (carbon dioxide + ω-pentadecalactone) and for the pseudoternary system involving (carbon dioxide + ω-pentadecalactone + chloroform) have been measured in order to provide fundamental information to conduct the polymerization reaction in supercritical carbon dioxide medium. The experiments were performed using a variable-volume view cell over the temperature range from 313 K to 343 K, system pressure between 5.4 MPa and 26.1 MPa and different mass ratios of chloroform to (ω-pentadecalactone) (0.5:1, 1:1 and 2:1). Phase transitions of vapour-liquid, liquid-liquid and vapour-liquid-liquid types were observed. The experimental results were modelled using the Peng-Robinson (PR) equation of state with the Wong-Sandler (PR-WS) mixing rule, providing a good representation of the experimental phase equilibrium data.

Phase equilibrium data for systems composed of oregano essential oil compounds and hydroalcoholic solvents at T = 298.2 K

The deterpenation process of essential oils consists of terpene removal and a consequent concentration of oxygenated compounds, which increases the sensorial quality, the aromatic potential and the oxidative stability of the oil. Deterpenation of oregano (Origanum vulgare L., Lamiaceae) essential oil, which has been used extensively as a popular medication and as an antimicrobial, antifungal, antimutagenic and a powerful antioxidant agent, can be performed by (liquid+liquid) extraction using hydroalcoholic solvents. This research presents (liquid+liquid) equilibrium data for model systems composed of p-cymene, thymol, terpinen-4-ol and α-terpineol, some of the main components of oregano essential oil, using hydrous ethanol as the solvent with the water mass fraction ranging from 0.28 to 0.41 at T=(298.2±0.1)K. The results show that an increase in the hydration of the alcoholic solvent causes a negative influence on the values of the distribution coefficient for the three oxygenated compounds (thymol, terpinen-4-ol and α-terpineol), with an increase in solvent selectivity. An increase in the content of oxygenated compounds in the terpene-rich phase reduces their distribution coefficients and the selectivity values. In addition, binary interaction parameters were estimated correlating the experimental data using the NRTL and UNIQUAC thermodynamic models, and the global deviations were lower than 0.0060 for all systems, indicating that both molecular models show a good descriptive performance.

Solubility of Supercritical Fluids in Ionic Liquids

AbstractEine umfangreiche Literaturrecherche zur Löslichkeit von nahe‐ bzw. überkritischen Fluiden (SCF) in Ionischen Flüssigkeiten (IL) zeigte, dass in der Regel die Gaslöslichkeit in den IL mit zunehmendem Druck und sinkender Temperatur zunimmt und dass unpolare, im Gegensatz zu polaren, SCF nur begrenzt in IL löslich sind. Diese Daten konnten mithilfe der Peng‐Robinson‐Zustandsgleichung unter Verwendung der Van‐der‐Waals‐Mischungsregeln mit zwei binären Wechselwirkungsparametern sehr gut beschrieben werden.

Phase equilibrium data of hydrogen in pyrolysis oil and hydrogenated pyrolysis oil at elevated pressures

Phase equilibrium data for the system hydrogen/pyrolysis oil as well as hydrogenated pyrolysis oils, at temperatures from 353.15K to 423.15K and pressures from 3.0MPa up to 17.2MPa were measured. The procedure was verified by measuring the phase equilibrium data for systems CO2/water and H2/water in the pressure range from 8.0MPa up to 35.0MPa at temperatures from 313.15K up to 353.15K. The high pressure solubility data for above mentioned systems were studied using a static-analytical method in an optical high pressure cell. The solubility increases with pressure at constant temperature, and decreases at increasing temperature. The solubility of bio oils in H2 increases with pressure and with temperature.

High-pressure phase equilibrium data for systems with carbon dioxide, α-humulene and trans-caryophyllene

The aim of this work is to report phase equilibrium data for the binary systems (CO 2 + α-humulene) and (CO 2 + trans-caryophyllene), and for the ternary system (CO 2 + α-humulene + trans-caryophyllene). Results from literature show that α-humulene and trans-caryophyllene are the main compounds responsible for the anti-inflammatory and anti-allergic characteristics attributed to the medicinal plant Cordia verbenacea D.C., hence giving importance to the phase behaviour investigation performed in this work. Phase equilibrium experiments were performed in a high-pressure, variable-volume view cell over the temperature range of T = (303 to 343) K and pressures up to 20 MPa. (Liquid + liquid) and (vapour + liquid + liquid) equilibrium were observed at T = 303 K, while (vapour + liquid) phase transitions were verified to occur from T = (313 to 343) K, for all systems studied. Thermodynamic modelling was performed using the Peng–Robinson equation of state and the classical quadratic mixing rules, with a satisfactory agreement between experimental and calculated values.