Vapor‐liquid equilibrium constants at infinite dilution determined by a gas stripping method: Ethane, propane, n‐butane, n‐pentane in the methane‐n‐decane system

Abstract

A new apparatus to measure partition coefficients K: at infinite dilution up to 200 lo5 Pa and 423 K is described. Measurements of the systems: (1) methane-ethane-ndecane and methane-propane-n-decane at 294.25 K; and (2) methane-n-butane-ndecane at 344.25 K illustrate the reproducibility and good agreement with literature data. In addition, new data were obtained for the system methane-n- SCOPEVapor-liquid distribution ratio of light hydrocarbons between a gas phase made of methane and a liquid phase composed of heavy hydrocarbons are needed in industrial applications, for instance pipe line design or tertiary oil recovery using a miscible gas. For infinitely diluted light hydrocarbons, determination of partition coefficients, KT, can be performed using a static apparatus (Reamer et al., 1949) or retention time in gas-liquid chromatography using CHI as carrier gas and the heavy component as stationary phase (Stalkup and Kobayashi, 1963a; Koonce and Kobayashi, 1964).The new method introduced in this paper consists of stripping the solute by a constant flow of gas from a solution contained in one vessel. The solution (mainly heavy hydrocarbons) and the gas (mostly CHI in this paper) have the composition corresponding to the equilibrium in the conditions of pressure and temperature of the measurement. The distribution ratio of the very diluted solute is related to the decrease in time of the concentration of the solute in the gas phase after stripping as determined by gas chromatography. This new technique is an extension to higher pressures of the method described by Leroi et al. (1977) and . It uses a saturator for the gas stream entering the stripping cell. CONCLUSIONS AND SIGNIFICANCEA new apparatus for measuring partition coefficients of infinitely diluted solutes in mixed solvent (gas dissolved in heavy components) has been designed, constructed and tested. Tests mixtures have been used to check the reliability of measurements. The results show a good agreement with the literature data. The experimental error on KT measurements is estimated at less than 2%.The method is fast and may be used for studying several solutes simultaneously if all solute chromatographic peaks can be resolved. Accurate measurements are possible even for volatile solvents. Such measurements are impossible with a retention time chromatographic method. The accuracy is better than in the static methods.

Measurements of Infinite-Dilution Ternary Activity Coefficients by Gas Stripping. Acetonitrile−Benzene−n-Heptane at 318.15 K

“…Actually, 6 of them are γ ∞ A(B) if their solvents are of one component. The deviations of these measurements, analyzed as in Legret et al (1983), are not larger than 4%. They were caused mainly by errors in detection of the desorption rates A of the solute concentration.…”

Solubility of Solids and Liquids in Supercritical Fluids

“…Barber et al (1991) made use of the quadrupole mass spectrometer directly coupled to the apparatus to analyze the effluent stream of the SCF carbon tetrafluoride -solid carbon tetrachloride system, providing a method of on-line analysis. The gas stripping method developed for pressures up to 20 MPa by Legret et al(1983) can also be considered as a particular variant of the saturation method. The technique enables rapid accumulation of data on partitioning of solvents at infinite dilution in systems of the type nonvolatile solute -volatile solvent.…”

Precision Methods for the Determination of the Solubility of Gases in Liquids

“…The reproducibility is usually in the 1 to 2% region. Recently, the method has been extended to cover VLE in multicomponent systems, 238 should prove valuable in a variety of industrial applications involving systems composed of light and heavy hydrocarbons, for instance in pipeline design or tertiary oil recovery.…”