Elsevier

Fluid Phase Equilibria

Volume 296, Issue 1, 15 September 2010, Pages 25-29
Fluid Phase Equilibria

Compact apparatus for rapid measurement of high-pressure phase equilibria of carbon dioxide expanded liquids

https://doi.org/10.1016/j.fluid.2009.12.030Get rights and content

Abstract

A new apparatus based on a synthetic method was developed for phase equilibrium measurements. The characteristic features of the apparatus are its light weight (ca. 288 g), variable-volume with a free piston, position sensing device for the piston, precise pressure and temperature control, and a window for visual observation. The inner volume of the cell can vary from 2.5 to 8.8 cm3. The cell was constructed from titanium so that the composition of the sample can be determined by direct weighing of the cell. The apparatus was designed for temperatures up to 473 K and pressures up to 25 MPa.

To confirm the reliability of the apparatus, vapor–liquid equilibria of the carbon dioxide–methanol system were measured. The estimated uncertainties of temperature, pressure, and composition of carbon dioxide were less than ±0.05 K, ±0.02 MPa, ±0.20 wt%, respectively. Bubble-point pressures obtained in this work agreed well with the literature data. Bubble-point pressure data for carbon dioxide with acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBE) were measured at temperatures ranging from 313 to 353 K, and could be correlated well with the Peng–Robinson equation of state. The Px diagrams at a given temperature for acetone, MEK, and MIBK binaries with carbon dioxide were found to be practically identical.

Introduction

Volatile organic compounds (VOC) emissions must be reduced to address environmental problems, such as photochemical smog and global warming. Among the many industries, the paint industry is the largest source of VOC emissions. VOCs are used as the carrier and the diluent of polymers and pigments in paints. Although aqueous coatings and powder coatings are used as one method to reduce VOCs, these techniques cannot be applied to all surfaces due to coating quality and conformability. Lewis et al. [1] proposed a spray coating system using supercritical carbon dioxide as a viscosity reduction solvent. This new painting method for VOC reduction gained much attention. Carbon dioxide is environmentally benign and highly soluble in VOCs. However, adding a supercritical fluid to polymer solutions can cause phase separation and formation of polymer-rich and solvent-rich phases [2]. To consider alternative solvents, information on the phase equilibria of paint mixtures including carbon dioxide are needed to develop low VOC coatings or new paint formulations. Further, since there are so many combinations of polymers and solvents possible for paint, a method to allow rapid measurement of the phase equilibria is needed. In this work, our objective was to construct an apparatus that allows rapid measurement of high-pressure phase equilibria and that could be used to measure carbon dioxide–solvent systems. We report on the measurements of carbon dioxide–solvent binary systems that have application to paints and coatings.

Until now, many apparatus have been proposed for phase equilibria measurements [3]. A method that does not require composition analysis is favorable since it eliminates time-consuming analysis steps. The synthetic method [4], [5] was chosen to be appropriate considering the objectives.

Solubilities of carbon dioxide in methanol were measured at temperature 313 and 330 K to confirm reliability of the developed apparatus. Moreover, solubilities of carbon dioxide in three kinds of ketones (acetone, methyl ethyl ketone, and methyl isobutyl ketone) are reported.

Section snippets

Experimental

Carbon dioxide (purity > 99.99%) supplied from Showa Tansan Co. Ltd. Methanol (purity > 99.8%), acetone (purity > 99.8%), methyl ethyl ketone (MEK) (purity > 99%), and methyl isobutyl ketone (MIBK) (purity > 99.5%) were purchased from Wako Pure Chemical Industries, Ltd. All compounds were used without further purification.

The synthetic method was used for the measurement of phase equilibria of carbon dioxide expanded liquids, in which bubble-point pressures were determined at various temperatures for

Results and discussion

The solubility of carbon dioxide in methanol was measured to confirm the reliability of the apparatus. Relationships between pressure and position of the piston for the carbon dioxide + methanol system are shown in Fig. 3. In the figure, solid and open symbols denote the single phase and the vapor–liquid coexisting phases, respectively. Intersection of lines of the vapor and liquid compressibilities can be seen in the figure. Bubble-point pressures were determined from these intersections.

Conclusion

A new apparatus based on synthetic method was developed. This apparatus can be used to rapidly obtain phase equilibria data. Solubilities of carbon dioxide in acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) were measured at temperatures of 313, 333, and 353 K. The solubilities of carbon dioxide in these ketones at a given pressure were found to be practically identical over the given range of temperature. The quadrupole moment of the carbon dioxide and its interaction with

References (13)

  • D. Richon

    Fluid Phase Equilib.

    (1996)
  • Y. Sato et al.

    Fluid Phase Equilib.

    (1998)
  • T.W. De Loos et al.

    J. Chem. Thermodyn.

    (1980)
  • J.H. Hong et al.

    Fluid Phase Equilib.

    (1988)
  • J. Lewis et al.

    Met. Finish.

    (2000)
  • M.A. McHugh et al.

    Macromolecules

    (1985)
There are more references available in the full text version of this article.

Cited by (40)

  • Vapor-liquid equilibrium, liquid density and excess enthalpy of the carbon dioxide+acetone mixture: Experimental measurements and correlations

    2021, Fluid Phase Equilibria
    Citation Excerpt :

    Density values calculated with Eq. (17) were compared with reported data (Figs. 7–9) at the different temperatures. In general, our data agree with refs. [11,12,17,21], with an ADR% below 5 %. References [7,10] show an ADR% lower than 9 % with our values, although with deviations up to 36 % in [7] for the data near the critical point.

  • Vapour-liquid equilibrium of acetone-CO<inf>2</inf> mixtures of different compositions at the vicinity of the critical point

    2019, Journal of CO2 Utilization
    Citation Excerpt :

    Further, physico-chemical and solvation properties of such mixtures, often called as CO2-expanded liquids [1], can be fine tuned through their composition. Due to this increasing interest, the properties of CO2-acetone mixtures have been investigated both by experimental [2–25] and computer simulation methods [17,20,26–30] in the past decades. The majority of these studies focused on the properties of the one-phase mixtures [6,11–13,18,20,22,23,27,29,30], including selective solvation of various solutes in such systems [20,30], or on their vapour-liquid equilibrium in a narrow temperature range, usually between 291 and 313 K [25,7,9,10,14,16,17,19,21,26,28].

View all citing articles on Scopus
View full text