Elsevier

Fluid Phase Equilibria

Volume 247, Issues 1–2, 15 September 2006, Pages 143-148
Fluid Phase Equilibria

Henry's law constants of 1-butene, 2-methylpropene, trans-2-butene, and 1,3-butadiene in methanol at 374–490 K

https://doi.org/10.1016/j.fluid.2006.06.024Get rights and content

Abstract

Henry's law constants of 1-butene, 2-methylpropene, trans-2-butene, and 1,3-butadiene in methanol in the temperature range of 374–490 K are experimentally obtained. A similar method to a gas stripping method is applied to measure the Henry's law constants at high temperatures up to the critical point of methanol. The rigorous formula for evaluating the Henry's law constants from these measurements is applied to the data reduction for these highly volatile mixtures. By using this formula, a volume effect of vapor phase is discussed. The plot of Henry's law constants versus temperature goes through a maximum and approaches an unique point at the critical temperature of methanol. The fugacity coefficient of the solute in the vapor phase at infinite dilution and the infinite dilution activity coefficient of the solute in liquid phase are evaluated from these experimental data.

Introduction

The study of gas solubilities is useful in providing design data for absorption processes, as well as, indirectly, in aiding the analysis of molecular interactions in solutions. For practical use, much attention has been given to the thermodynamic properties near the critical point of mixtures. High temperature data are rarely available and are difficult to measure. Hayduk and Buckley [1] observed that all gas solubilities in a solvent tend towards a common value as the solvent critical temperature is approached. Beutier and Renon [2] and Schotte [3] showed that this is due to the thermodynamic relationship for the solute (g) at the solvent (s) critical pointHgφgVTc,s=Pc,sdlnHgdTTc,s=,d(Hg/φgV)dTTc,s=where Hg is the Henry's law constant of the solute, φgV the fugacity coefficients of the solute in the vapor phase, Pc,s the critical pressure of the solvent and Tc,s the critical temperature of the solvent, and T is the absolute temperature.

Oxygenates such as ethers and alcohols have been used widely as fuel additives to increase the octane number, improve the combustion process, and reduce emissions, and solubility data of gases in alcohols are needed in the design of these production facilities.

To develop a molecular theory, on the other hand, an accurate intermolecular potential is necessary. Henry's law constant is directly related to the residual chemical potential of the solute at infinite dilution that is evaluated from the intermolecular potential between a solute molecule and a solvent molecule. Therefore Henry's law constant is a suitable macroscopic property for correlating the intermolecular potential between different kinds of molecules.

The gas stripping method that was originally proposed by Leroi et al. [4] is usually used to measure the activity coefficients at infinite dilution of solutes in nonvolatile solvents, when the total pressures are negligibly small.

In the previous paper [5], [6], Henry's law constants of carbon dioxide, propane, propene, butane, and 2-methylpropane in methanol at temperatures up to the critical temperature of methanol were measured by the similar method to the gas stripping method. An interesting phenomenon was observed that the plot of the infinite dilution activity coefficients of the solutes versus temperature tended towards a common value as the solvent critical temperature was approached. In this work, to support this interesting phenomenon and to compare the difference between alkanes and alkenes in the solubility phenomena, the Henry's law constants of 1-butene, 2-methylpropene, trans-2-butene, and 1,3-butadiene in methanol at high temperatures and high pressures are measured by the same method and the activity coefficients and the fugacity coefficients of the solute at infinite dilution are evaluated from these experimental data.

In the literatures, we have found the following experimental data of the mixtures studied in this work. The Henry's law constants in methanol were measured for trans-2-butene and 1,3-butadiene at 255–320 K by Miyano and Fukuchi [7], and for 1-butene and 2-methylpropene at 255–320 K by Miyano et al. [8]. The gas solubilities in methanol at 298.15 K and pressures less than 102 kPa were measured for 2-methylpropene by Miyano and Nakanishi [9], and for 1-butene by Miyano and Nakanishi [10]. The vapor–liquid equilibria were measured for 1,3-butadiene + methanol system at 323.15 K by Churkin et al. [11], 1-butene + methanol system at 326 K by Laakkonen et al. [12], trans-2-butene + methanol system at 332 K by Zaytseva et al. [13], and 2-methylpropene + methanol system at 323.15 by Ouni et al. [14]. At higher temperatures than 340 K, no data are available in the literature.

Section snippets

Experimental

The gas stripping method originally proposed by Leroi et al. [4] is based on the variation of vapor phase composition when the highly diluted solute in a liquid mixture in an equilibrium cell is stripped from the solution by a flow of inert gas (helium). The composition of the gas leaving the cell is periodically sampled and analyzed by means of gas chromatography. The peak area, S, of the solute decreases exponentially with the volume of inert gas flowing out of the cell. This rigorous

Results and discussion

As indicated in Eq. (3), Hg/φgV can be obtained directly from this experiment. Fig. 1 shows the temperature dependencies of Hg/φgV of 1-butene, 2-methylpropene, trans-2-butene, and 1,3-butadiene in methanol in the temperature range of 250–490 K. As shown in this figure, the values of Hg/φgV obtained in this work are smoothly combined with those obtained by using the gas stripping method at lower temperatures [7], [8]. The smoothed lines are the calculated results from the Soave equation of state

Conclusion

Henry's law constants for 1-butene, 2-methylpropene, trans-2-butene, and 1,3-butadiene in the methanol divided by the fugacity coefficient, Hg/φgV, have been directly measured by the similar experimental apparatus to the gas stripping method in a very wide temperature range of 374–490 K. The value of Hg/φgV increases with the temperature, goes through a maximum around at 470 K, and approaches the critical point of the solvent with a slope of −∞. The Henry's law constants of gases in methanol

Acknowledgements

This paper reports part of the work supported by Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science (16560663), which is gratefully acknowledged.

References (18)

  • Y. Miyano et al.

    Fluid Phase Equilibr.

    (2004)
  • Y. Miyano et al.

    Fluid Phase Equilibr.

    (2006)
  • Y. Miyano et al.

    Fluid Phase Equilibr.

    (2004)
  • Y. Miyano et al.

    Fluid Phase Equilibr.

    (2003)
  • Y. Miyano et al.

    Fluid Phase Equilibr.

    (2003)
  • Y. Miyano et al.

    J. Chem. Thermodyn.

    (2003)
  • M. Laakkonen et al.

    Fluid Phase Equilibr.

    (2003)
  • G. Soave

    Chem. Eng. Sci.

    (1972)
  • W. Hayduk et al.

    Can. J. Chem. Eng.

    (1971)
There are more references available in the full text version of this article.

Cited by (6)

  • Modeling hydrogen solubility in alcohols using group method of data handling and genetic programming

    2023, International Journal of Hydrogen Energy
    Citation Excerpt :

    In recent years, researchers are convinced to look for more convenient, accurate, and rapid modeling approaches for predicting H2 solubility in different solvents because of EOSs drawbacks such as adjustable parameters, iterative calculations, and limited flexibility [11–16]. During the past years, dissolutions of various gases such as methane, butane, propane, nitrogen, carbon dioxide, and so on in alcohols have been investigated [17–21]. In addition, researchers experimentally studied H2 solubility in different alcohols [1,2,4,7,8,10,22–25].

  • Modeling hydrogen solubility in alcohols using machine learning models and equations of state

    2022, Journal of Molecular Liquids
    Citation Excerpt :

    Disadvantages such as limited flexibility, iterative calculations, and adjustable parameters make the use of common traditional methods such as EOSs unreliable and convince researchers to look for better modeling methods for gas solubility [10–15]. The solubility of gases such as carbon dioxide, nitrogen, methane, propane, butane, etc., in alcohols has been studied over the past years [16–19]. Also, the solubility of H2 in alcohols has been experimentally investigated by researchers [1,2,5–7,9,20–23].

  • Prediction of limiting activity coefficients for binary vapor-liquid equilibrium using neural networks

    2017, Fluid Phase Equilibria
    Citation Excerpt :

    5). These data include experimental published data on the IDAC of binary systems from different literature [1,28,31–50]. The data set used in the development of the neural model contains aqueous systems and both hydrocarbon and non-hydrocarbon compounds of various types including alcohols, amines, ketones, carboxylic acids, aldehydes, esters, ethers, nitriles and halogenated hydrocarbons in solute and solvent categories as well.

View full text