Carbon dioxide, binary mixtures

For the prediction of the mixed-gas solubilities from the solubilities of the pure individual gases, the pressure dependence of the binary parameters ku is needed. The Peng—Robinson EOS was used to determine the binary parameters ku. The binary interaction parameter qi2 in the van der Waals mixing rule was taken from ref 28, where it was evaluated for the water-rich phases of water—hydrocarbon and water—carbon dioxide binary mixtures. The calculated binary parameters ku are listed in Table 1. One should note that, as expected for a liquid phase, the above parameters are almost independent of pressure, in contrast to their dependence on pressure in the gaseous phase near the critical point,... 

Although comparisons for the steam-methane system have been presented, similar trends were noted for the other binary systems previously published by Wormald, namely mixtures of steam with nitrogen, carbon dioxide, n-hexane, and benzene. 

The mixture to be separated is fed, together with the entrainer, to the middle of the first column. Flere, the solvent, carbon dioxide and acetone, is supercritical to provide high solubility of the monoglycerides. The supercritical phase leaves the top of column I and goes to the lower part of column II. In column II, the binary solvent entrainer is subcritical and in the bottom of this column, the monoglyceride leaves, together with the entrainer. Part of it is returned as reflux to column I, whereas the rest goes to distillation for the separation of acetone. With a bottom temperature of... 

Extraction of 25 different binary mixtures of racemic acids (2-(4-isobutylphenyl)-propionic acid (1), and cis- and trans-chrysanthemic (2)), and various chiral bases with supercritical carbon dioxide permitted the conclusion that molecular chiral differentiation in a supercritical fluid is more efficient than in conventional solvents. In the majority of cases, however, complete separation could not be achieved. In five cases, remarkable partial resolutions were realized (30-75% ee) and resolution was possible on a preparative scale. The pair ds-chrysanthemic acid and (S)-(-i-)-2-(benzylamino)-1-butanol (3) was studied in detail. Pressure, temperature, and time, as well as the molar ratio of base and acid, had a marked influence on the quantity and quality of the products. Increasing pressure or decreasing temperature resulted in higher ee values. (-)-cw-Chrysanthemic acid in 99% ee was obtained from the raffinate in a single extraction step. Multiple extractions produced the (-i-)-cA-acid in 90% ee (see fig. 6.3) (Simandi et al., 1997). 

Figure 15.5. Adsorption of binary mixtures (1) ethane + ethylene. Type 4A MS 25°C, 250Torr (2) ethane + ethylene. Type 4A MS, 25°C, 730Torr (3) ethane + ethylene. Type 4A MS, 75°C, 730Torr (4) carbon dioxide + hydrogen sulfide. Type 5A MS, 27°C, 760Torr (5) n-pentane + n-hexane, type 5A MS, 100°C, 760 Torr (6) ethane + ethylene, silica gel, 25°C, 760 Tort (7) ethane + ethylene, Columbia G carbon, 25°C, 760 Torr (8) acetylene + ethylene. Type 4A MS, 31°C, 740 Torr. (Data from Union Carbide Corp.)...

Of the natural gas components that form simple hydrates, nitrogen, propane, and iso-butane are known to form structure II. Methane, ethane, carbon dioxide, and hydrogen sulfide all form si as simple hydrates. Yet, because the larger molecules of propane and iso-butane only fit into the large cavity of structure II, natural gas mixtures containing propane and iso-butane usually form structure II hydrate (see Section 2.1.3.3 in the subsection on structural changes in binary hydrate structure). 

In the discussion appendix of the original paper by Carson and Katz (1942), Hammerschmidt indicated that, while the method was acceptable for gases of normal natural gas composition, an unacceptable deviation was obtained for a gas rich in ethane, propane, and the butanes. More work is also required to revise the Kvs -value charts for two components, namely, carbon dioxide and nitrogen. In three-phase hydrate data for binary mixtures of carbon dioxide and propane, Robinson and Mehta (1971) determined that the Kvs method for carbon dioxide gave unsatisfactory results. The API Data Book shows the Kvs values for nitrogen to be only a function of pressure, without regard for temperature Daubert (Personal... 

The phase equilibria data for binary guest mixtures are listed under the lighter component. For example, under the heading of binary guest mixtures of methane will be found data for methane + ethane, methane + propane, methane + isobutane, methane + n-butane, methane + nitrogen, methane + carbon dioxide, and methane + hydrogen sulfide. Concentrations are in mole percent or mole fraction in the gas phase, unless otherwise indicated. 

Binary Guest Mixtures Containing Nitrogen and Carbon Dioxide... 

Binary Mixtures of Methane + Carbon Dioxide with Inhibitors... 

With binary and ternary supercritical mixtures as chromatographic mobile phases, solute retention mechanisms are unclear. Polar modifiers produce a nonlinear relationship between the log of solute partition ratios (k ) and the percentage of modifier in the mobile phase. The only form of liquid chromatography (LC) that produces non-linear retention is liquid-solid adsorption chromatography (LSC) where the retention of solutes follows the adsorption isotherm of the polar modifier (6). Recent measurements confirm that extensive adsorption of both carbon dioxide (7,8) and methanol (8,9) occurs from supercritical methanol/carbon dioxide mixtures. Although extensive adsorption of mobile phase components clearly occurs, a classic adsorption mechanism does not appear to describe chromatographic behavior of polar solutes in packed column SFC. 

Tertiary systems. With methanol/carbon dioxide mixtures the addition of even the most polar additives has only a small impact on the mobile phase solvent strength as measured with Nile Red. With TFA concentrations below 1 to 2 % in methanol, ternary mixtures of TFA/methanol/carbon dioxide produce the same apparent solvent strength as binary methanol/carbon dioxide mixtures. As much as 5 or 10 % TFA in methanol is required to noticeably increase the solvent strength of TFA/methanol/carbon dioxide mixtures above those for binary methanol/carbon dioxide mixtures, as shown in Figure 4. 

Dholabhai PD, Parent JS, Bishnoi PR (1997) Equilibrium conditions for hydrate formation from binary mixtures of methane and carbon dioxide in the presence of electrolytes, methanol and ethylene glycol. Fluid Phase Equilibria 141 235-246... 

The NMR method we have developed gives a direct, in situ determination of the solubility and also allows us to obtain phase data on the system. In this study we have measured the solubilities of solid naphthalene in supercritical carbon dioxide along three isotherms (50.0, 55.0, and 58.5°C) near the UCEP temperature over a pressure range of 120-500 bar. We have also determined the pressure-temperature trace of the S-L-G phase line that terminates with the UCEP for the binary mixture. Finally, we have performed an analysis of our data using a quantitative theory of solubility in supercritical fluids to help establish the location of the UCEP. 

When applying an equation of state to both vapor and liquid phases, the vapor-liquid equilibrium predictions depend on the accuracy of the equation of state used and, for multicomponent systems, on the mixing rules. Attention will be given to binary mixtures of hydrocarbons and the technically important nonhydrocarbons such as hydrogen sulfide and carbon dioxide -Figures 6-7. 

A recirculation apparatus for the determination of high pressure phase equilibrium data for mixtures of water, polar organic liquids and supercritical fluids was constructed and operated for binary and ternary systems with supercritical carbon dioxide. 

We have applied some of these principles to the extraction of 1-butene from a binary mixture of 1,3-butadiene/1-butene. Various mixtures of sc solvents (e.g., ethane, carbon dioxide, ethylene) are used in combination with a strongly polar solvent gas like ammonia. The physical properties of these components are shown in Table I. The experimental results were then compared with VLE predictions using a newly developed equation of state (18). The key feature of this equation is a new set of mixing rules based on statistical mechanical arguments. We have been able to demonstrate its agreement with a number of binary and ternary systems described in the literature, containing various hydrocarbon compounds, a number of selected polar compounds and a supercritical component. 

The binary mixture hydrogen sulfide + carbon dioxide is the most important non-aqueous system involved in acid gas injection, since acid gas is composed almost exclusively of these components. 

Two early studies of the phase equilibrium in the system hydrogen sulfide + carbon dioxide were Bierlein and Kay (1953) and Sobocinski and Kurata (1959). Bierlein and Kay (1953) measured vapor-liquid equilibrium (VLE) in the range of temperature from 0° to 100°C and pressures to 9 MPa, and they established the critical locus for the binary mixture. For this binary system, the critical locus is continuous between the two pure component critical points. Sobocinski and Kurata (1959) confirmed much of the work of Bierlein and Kay (1953) and extended it to temperatures as low as -95°C, the temperature at which solids are formed. Furthermore, liquid phase immiscibility was not observed in this system. Liquid H2S and C02 are completely miscible. 

Robinson and Bailey (1957) and Robinson et al. (1959) studied the VLE in the ternary mixtures of hydrogen sulfide + carbon dioxide + methane. These investigations also included a few points for the binary system H2S + C02. The points for the binary mixtures were at temperatures between 4° and 71 °C and at pressures from 4 to 8 MPa. 

For mixtures of carbon dioxide and hydrogen sulfide, a binary critical locus extends from the critical point of COz and terminates at the critical point of H2S. This is the case for H2S and COz, but not for all binary mixtures. 

For binary mixtures of hydrogen sulfide and carbon dioxide, the critical locus extends uninterrupted from the critical point of C02 to that of H2S. The critical point of a binary mixture can be estimated from the next two figures. Figure 3.4 shows the critical temperature as a function of the composition, and figure 3.5 gives the critical pressure. 

Kaminishi, G., Arai, S. Saito, and S. Maeda. 1968. "Vapor-Liquid Equilibria for Binary and Ternary Mixtures Containing Carbon Dioxide",/. Chem. Eng. Japan, 1 109-116. 

Roof, J.G. and Baron, J.D. 1967. "Critical Loci of Binary Mixtures of Propane with Methane, Carbon Dioxide, and Nitrogen", ]. Chem. Eng. Data, 12 292-293. 

Table 3B.2 The performance of three equations of state for predicting the phase behavior of binary mixtures of carbon dioxide and other components in the acid gas mixture.

Bamberger, A.G. Sieder, and G. Maurer. 2000. High-pressure (vapor + liquid) equilibrium in binary mixtures of (carbon dioxide + water or acetic acid) at temperatures from 313 to 353 K. /. Supercrit. Fluids 17 97-110. 

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