High pressure phase behavior for carbon dioxide-1-butanol and carbon dioxide-1-octanol systems

Pressure-composition isotherms are obtained for binary mixtures of carbon dioxide-1-butanol and carbon dioxide-1-octanol systems at 40, 60, 80, 100, and 120 °C and pressures up to 220 bar. The accuracy of the experimental apparatus was tested by comparing the measured phase equilibria data of the carbon dioxide-1-butanol system at 40 °C with those of Ishihara et al. [1996]. The solubility of 1-butanol and 1-octanol for the carbon dioxide-1-butanol and carbon dioxide-1-octanol systems increases as the temperature increases at constant pressure. The carbon dioxide-1-butanol and carbon dioxide-1-octanol systems have continuous critical mixture curves that exhibit maximums in pressure at temperatures between the critical temperatures of carbon dioxideand 1-butanol or 1-octanol. The carbon dioxide-1-butanol system exhibits type-I phase behavior, characterized by a continuous critical line from pure carbon dioxide, to the second component with a maximum in pressure. Also, the carbon dioxide-1-octanol system exhibits type-I curve at 60–120 °C, and shows liquid-liquid-vapor phase behavior at 40 oC. The experimental results for the carbon dioxide-1-butanol and carbon dioxide-1-octanol systems have been modeled by the Peng-Robinson equation of state. A good fit of the data is obtained with the Peng-Robinson equation by using two adjustable interaction parameters for the carbon dioxide-1-butanol system and a poor fit using two adjustable parameters for the carbon dioxide-1-octanol mixture.     

High pressure phase behavior for the binary mixture of pentafluoropropyl methacrylate and poly(pentafluoropropyl methacrylate) in supercritical carbon dioxide and dimethyl ether

Pressure-composition isotherm is obtained for the carbon dioxide+2,2,3,3,3-pentafluoropropyl methacrylate (PFPMA) using static apparatus with a variable volume view cell at temperature range from 40 °C to 120 °C and pressure up to 130 bar. This system exhibits type-I phase behavior with a continuous mixture-critical curve. The experimental result for carbon dioxide+PFPMA mixture was modeled using the Peng-Robinson (P-R) and multi-fluid nonrandom lattice fluid (MF-NLF) equation of state. Experimental cloud-point data of pressure up 470 bar and temperature to 182 °C were reported for the binary mixture of poly(2,2,3,3,3-pentafluoropropyl methacrylate) [Poly(PFPMA)] in supercritical carbon dioxide and dimethyl ether (DME). The Poly(PFPMA)+carbon dioxide and Poly(PFPMA)+DME systems showed LCST behavior.     

Vapor-liquid equilibria of carbon dioxide and nonionic surfactant system at elevated pressures

Aqueous solutions of the polyoxyethylene nonionic amphiphiles have been extensively investigated at atmospheric pressure, but only a few data of nonionic amphiphile — carbon dioxide system are available at elevated pressures. Isothermal vapor-liquid equilibrium data for the binary ethylene glycol propyl ether (C3E1) — carbon dioxide system at 313.15 K, 323.15 K were measured at elevated pressures. We used two-phase circulating type equipment with a view cell. Modeling of the experimental data has been performed using the Peng-Robinson equation of state, statistical associating fluid theory (SAFT) and Sanchez-Lacombe equation of state.     

超临界二氧化碳和醇类体系的相平衡计算

应用Peng-Robinson(P-R)状态方程对超临界CO2系统进行了相平衡模拟。对超临界CO2和醇类二元系统进行了汽液相平衡计算,结果表明,P-R状态方程模拟高压下CO2系统的相平衡具有较高的精度。     

Cloud point behavior for poly(isodecyl methacrylate)+supercritical solvents+cosolvent and vapor-liquid behavior for CO<Subscript>2</Subscript>+isodecyl methacrylate systems at high pressure

Experimental cloud-point data of binary and ternary mixtures for poly(isodecyl methacrylate) [P(IDMA)] in supercritical carbon dioxide, dimethyl ether (DME), propane, propylene, butane and 1-butene have been studied experimentally using a high pressure variable volume view cell. These systems show the phase behavior at temperature of 308 K to 473 K and pressure up to 255 MPa. The cloud-point curves for the P(IDMA)+CO₂+isodecyl methacrylate (IDMA) are measured in changes of the pressure-temperature (P-T) slope, and with cosolvent concentrations of 0-60.1 wt%. Also, experimental data of phase behaviors for IDMA in supercritical carbon dioxide is obtained at temperature range of 313.2–393.2 K and pressure range of 5.8–22.03 MPa. The experimental results were modeled with the Peng-Robinson equation of state. The location of the P(IDMA)+CO₂ cloud-point curve shifts to lower temperatures and pressures when DME is added to P(IDMA)+CO₂ solution. The P(IDMA)+C₄ hydrocarbons cloud-point curves are ca. 16.0 MPa lower pressures than the P(IDMA)+C₃ hydrocarbons curves at constant temperature. This article is dedicated to Professor Chul Soo Lee in commemoration of his retirement from Department of Chemical and Biological Engineering of Korea University.     

Expanded ensemble Monte Carlo simulations for the chemical potentials of supercritical carbon dioxide and hydrocarbon solutes

We carry out expanded ensemble Monte Carlo simulations in order to calculate the chemical potentials of carbon dioxide as solvent and those of hydrocarbons as solutes at supercritical conditions. Recently developed adaptive method is employed to find weight factors during the simulation, which is crucial to achieving high accuracy for free energy calculation. The present simulation method enables us to obtain chemical potentials of large solute molecules dissolved in compressed phase from a single run of simulation. Simulation results for the excess chemical potentials of pure carbon dioxide at 300, 325 and 350 K are compared with experimental data and values predicted by the Peng-Robinson equation of state. A good agreement is found for high pressures up to 500 bar. The chemical potentials of hydrocarbon solutes dissolved in carbon dioxide at infinite dilution are predicted by simulation. Less than eight intermediate subensembles are required to gradually insert (or delete) hydrocarbon solute molecules from methane to noctane into dense CO₂ phase of approximately 1.0 g cm⁻³.     

High-pressure phase equilibrium for the hydroformylation of 1-octene to nonanal in compressed CO2

The hydroformylation reaction in supercritical carbon dioxide or CO₂-expanded liquids (CXLs) has many advantageous properties. However, accurate phase behavior and equilibrium must be known to properly understand and engineer these systems. In this investigation, the vapor-liquid equilibrium and mixture critical points of CO₂ systems with 1-octene, nonanal, 1-octene and nonanal mixtures, and mixtures of 1-octene, nonanal and syngas (CO/H₂) were measured at 60 °C up to 120 bar of pressure. The Peng-Robinson equation of state with van der Waals two-parameter mixing rule was employed successfully to correlate the binary mixture data and predict the ternary mixture data. The presence of CO/H₂ pressure increased the mixture critical points and decreased the volume expansion at any given pressure. In an actual reaction, the mixture critical point would increase throughout the reaction, while the volume of the liquid phase would decrease. These data will aid the understanding and reaction engineering for the hydroformylation reaction in CO₂-expanded liquids and supercritical fluids.     

Bubble-point pressures of the binary system carbon dioxide+linalool

A synthetic method was used to investigate high-pressure vapor–liquid equilibria of the binary system carbon dioxide+linalool. The bubble points of this system were measured at carbon dioxide mole fractions from 0.2 up to 0.993 and within temperature and pressure ranges of 283–371 K and 1.4–14.7 MPa, respectively. Critical points of this binary system were also determined experimentally for a carbon dioxide mole fraction range from 0.93 up to 0.993. The results were correlated by the Stryjek–Vera modified version of the Peng–Robinson equation of state using one-fluid van der Waals mixing rules with both one and two interaction parameters.     

Phase behavior measurement for the ethylene glycol dimethacrylate in supercritical carbon dioxide at temperatures between (313.2 and 393.2) K and pressures from (5.8 to 22) MPa

High pressure experimental data are presented on the phase equilibrium of ethylene glycol dimethacrylate in supercritical carbon dioxide. Pressure-composition (P-x) isotherms were measured in static method at five temperatures of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 22.0MPa. This (carbon dioxide+ethylene glycol dimethacrylate) system has continuous critical mixture curves that exhibit maximums in pressure at temperatures between the critical temperatures of carbon dioxide and ethylene glycol dimethacrylate. At a fixed pressure, the solubility of ethylene glycol dimethacrylate for the (carbon dioxide+ethylene glycol dimethacrylate) system increases with increasing temperature. The (carbon dioxide+ethylene glycol dimethacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide+ethylene glycol dimethacrylate) system is correlated with Peng-Robinson equation of state using mixing rule including two adjustable parameters. The critical property of ethylene glycol dimethacrylate is predicted with Joback and Lee-Kesler method.     

Viscosities of fatty acids and methylated fatty acids saturated with supercritical carbon dioxide

The viscosities of several types of lipids saturated with supercritical carbon dioxide (SC-CO₂) were measured with a high-pressure capillary viscometer. Oleic acid and linoleic acid were evaluated from 85 to 350 bar at 40 and 60°C. The more SC-CO₂-soluble methylated derivatives of these fatty acids were evaluated from 90 to 170 bar at 40 and 60°C. The complex mixture of anhydrous milk fat (AMF) was evaluated from 100–310 bar at 40°C. The viscosities of the methylated fatty acids saturated with SC-CO₂ decreased between 5 and 10 times when the pressure increased from 1 to 80 bar, followed by a further decrease by a factor of 2 to 3 when the pressure was increased from 80 to 180 bar. The viscosities of the fatty acids and AMF saturated with SC-CO₂ had viscosity reduction similar to the methylated fatty acids between 1 and 80 bar, but they decreased much less between 80 and 350 bar. At constant pressure, the viscosity of the fatty acids and AMF decreased with increasing temperature, whereas the viscosity of the methylated fatty acids increased with increasing temperature. The lipid/SC-CO₂ mixtures were Newtonian, and their viscosities were best interpreted by using the mass concentration of dissolved SC-CO₂ in the lipids and the pure component viscosities.     

Solubility of 2-ethyl-hexyl-2-ethyl hexanoate in binary and quaternary systems in supercritical carbon dioxide

Binary and quaternary solubility of 2-ethyl-hexyl-2-ethyl hexanoate (2E2E) in supercritical carbon dioxide have been measured at flow rate of 250±10 ml/min, and (a) constant temperature of 313 K in the pressure range of 90–253 bar, (b) constant pressure of 170 bar, in the temperature range of 313–353 K, and (c) constant temperature of 313 K and pressure of 170 bar in flow rate range of 100–300 ml/min. The quaternary solubilities of 2-ethyl-1-hexanol and 2-ethyl hexanoic acid in supercritical carbon dioxide (SC-CO₂) were found to be greater than of 2E2E at pressure of 170 bar, a temperature of 313 K, and a flow rate of 250±10 ml/min. There is an isosolubility range for the mixed-liquid of the acid and the ester. Solubility diminutions (∼69–75%) of 2E2E at different pressures were observed for the quaternary model system compared to the binary system in SC-CO₂.     

二氧化碳+重整汽油拟二元体系高压汽液平衡数据的测定及关联

为了满足超临界CO2回收溶剂法提取油砂沥青的提取溶剂重整汽油的工艺需要,采用可变体积高压相平衡装置,在温度为30.3～70.2℃下,测定了4.02～14.01MPa范围内CO2-重整汽油拟二元体系的气液两相的平衡组成、密度以及摩尔体积。通过得到的结果确定了利用超临界二氧化碳来回收重整汽油的操作条件范围。利用基团贡献法估算了重整汽油的特性参数。采用Peng-Robinson方程拟合回归实验数据,得到了CO2-重整汽油体系的交互参数,计算出CO2-重整汽油体系的相平衡数据,结果表明计算值与实验值吻合较好。     

Density correlation of solubility of C. I. disperse orange 30 dye in supercritical carbon dioxide

The solubility of C. I. Disperse Orange 30 (O30) dye in CO₂ has been measured by using a closed-loop (batch) solid-fluid equilibrium apparatus at temperatures between 313 and 393 K and at pressures between 11 and 33 MPa. Kumar and Johnston’s equation based on Chrastil’s concept has been used to describe the experimental solubility data. The solubility versus density plot appears much simpler than the solubility versus pressure plot. The isotherms are nearly straight and parallel to each other, as seen in the previous studies. Peng-Robinson equation of state (PR EOS) has also been used successfully in modeling the dye solubility in supercritical carbon dioxide as a function of pressure or density of the fluid phase. The validity of this method has been verified by the vapor pressure calculation. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Solubility of astaxanthin in supercritical carbon dioxide

The solubility of astaxanthin in carbon dioxide was measured under supercritical conditions of a pressure range from 80 to 300 bar, and temperature range from 303 to 333 K, by using a dynamic flow-type. The solubility of astaxanthin increasing from 0.42×10⁻⁵ to 4.89×10⁻⁵ with higher temperature and pressure maintains certain density of supercritical carbon dioxide. The solubility data obtained were applied to the Chrastil model, based on the density of carbon dioxide. The data fitted well with the Chrastil model at most experimental conditions.     

Supported platinum/tin complexes as catalysts for hydroformylation of 1-hexene in supercritical carbon dioxide

Platinum–phosphine complexes anchored on silica and on mesoporous MCM-41 supports were synthesized. Hydroformylation of 1-hexene was performed at 100 °C in supercritical carbon dioxide (pressure=2700 psi) using these supported platinum catalysts with SnCl₂ · 2H₂O (Sn:Pt=3.5:1) as co-catalyst. No hydrogenation was observed and high regioselectivity to heptanal was obtained.     

Ternary phase equilibria of the iso-propanol+water+carbon dioxide system at high pressure

Ternary phase diagrams are presented for the system: iso-propanol(IPA)+water+carbon dioxide at temperatures from 15 to 70 °C and pressures from 7 to 17 MPa. The distribution coefficients of IPA between the dense phase carbon dioxide and water changed dramatically with temperature and pressure. In the vicinity of the critical point, distribution coefficients was low, yet at liquid-like densities carbon dioxide had a high affinity for IPA. Selectivity reversal was observed at differing pressures. High selectivity of CO₂ for IPA was achieved in the near-critical liquid and in supercritical carbon dioxide at high pressure.     

Prediction of the infinite-dilution partial molar volumes of organic solutes in supercritical carbon dioxide using the Kirkwood-Buff fluctuation integral with the hard sphere expansion (HSE) theory

Two thermodynamic models were used to predict the infinite dilution partial molar volumes (PMVs) of organic solutes in supercritical carbon dioxide: (1) the Kirkwood Buff fluctuation integral with the hard sphere expansion (HSE) theory incorporated (KB-HSE fluctuation integral method) and (2) the Peng-Robinson equation of state with the classical mixing rule. While an equation of state only for pure supercritical carbon dioxide is needed in the KB-HSE fluctuation integral model, and thus, there is no need to know the critical properties of solutes, two molecular parameters (one size parameter σ₁₂ and one dimensionless parameter α₁₂) in the KB-HSE fluctuation integral model are determined to fit the experimental data published on the infinite dilution PMVs of solutes. The KB-HSE fluctuation integral method produced better results on the infinite dilution PMVs of eight organic solutes tested in this work than the Peng-Robinson equation of state with the classical mixing rule.     

Cycloaddition of carbon dioxide to butyl glycidyl ether using imidazolium salt ionic liquid as a catalyst

The catalytic performance of imidazolium salt ionic liquids in the cycloaddition of carbon dioxide to butyl glycidyl ether (BGE) was investigated. The catalytic activity was tested with different imidazolium salt ionic liquids at 60–140 °C under 0.62–2.17 MPa of CO₂ pressure. The imidazolium salt ionic liquid with the cation of bulkier alkyl chain length and with more nucleophilic anion showed higher conversion of BGE. High carbon dioxide pressure and high reaction temperature up to 140 °C was favorable for the high reactivity of the catalyst. The presence of zinc bromide co-catalyst enhanced the reactivity of the imidazolium salt ionic liquid. Kinetic studies with a semi-batch reactor revealed that the reaction could be considered as first order with respect to the concentration of BGE, and the activation energy was estimated as 22.6 and 22.8 kJ/mol for 1-ethyl-3-methylimidazolium chloride (EMImCl) and 1-butyl-3-methylimidazolium chloride (BMImCl), respectively.     

二氧化碳和丙烯酸酯体系的相平衡数据

利用可变体积高压釜,在313K、333K、353K和373K下,测定了二氧化碳分别与丙烯酸甲酯和丙烯酸丙酯二元体系的气液两相平衡数据。应用Peng-Robinson(P-R)状态方程对实验数据进行计算,计算结果与实验结果具有较高的一致性。本文还计算得到了不同温度和压力下二氧化碳在丙烯酸酯溶解过程中的Henry系数、偏摩尔焓变和偏摩尔熵变等热力学数据。     

In-line and off-line trapping of lipids extracted from chicken liver by supercritical carbon dioxide

This supercritical fluid extraction study determined the retentive properties of neutral alumina sorbent as an in-line trap for lipids in the dynamic state over a pressure range of 490–680 bar and temperatures of 40 and 80°C. Lipids were extracted from a chicken liver matrix using supercritical carbon dioxide over a 40-min period at a flow rate of 3 L/min (expanded gas), then were quantified by high-performance liquid chromatography using an evaporative light-scattering detector. Approximately 30 and 18%, respectively, of the total extracted lipids were trapped on the in-line alumina sorbent bed at 40°C as the operating pressure increased from 490 to 680 bar, while the remaining lipids were trapped off-line after CO₂ decompression. The major lipid classes trapped in-line were fatty acids and cholesterol, whereas only minor amounts of the less polar lipid classes such as sterol esters and triacylglycerols were retained. At 80°C and 680 bar, less than 1.5% of the extracted total lipids was trapped in-line, indicating the lack of adsorptive selectivity for lipids by alumina under these conditions.