High pressure vapor–liquid equilibrium measurements of carbon dioxide with naphthalene and benzoic acid
Introduction
High pressure vapor–liquid equilibrium (VLE) data were measured for CO2 + naphthalene at 372.45, 403.85 and 430.65 K and for CO2 + benzoic acid at 403.28, 432.62 and 458.37 K. Several sets of VLE data exist for the CO2 + naphthalene system in open literatures [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35]. The data, however, are predominately in the temperature range from 308 to 328 K. A few data sets for CO2 + benzoic acid are available in literatures [36], [37], [38], [39], [40], [41] in the temperature range from 308 to 343 K. In order to increase the range of applicability, in terms of temperature, of the predictive Soave–Redlich–Kwong equation of state (EOS), measurements were undertaken at the elevated temperatures.
The correlation and prediction of VLE is possible with cubic equations of state which have mixing rules that incorporate excess Gibbs energy models [42], [43], [44], [45], [46]. Furthermore, group contribution approaches such as UNIFAC can be used so that the applicability of methods, such as the predictive Soave–Redlich–Kwong (PSRK) group contribution EOS [47], are not restricted to systems for which experimental data are available. Data measured in this work are useful as they make the creating and refining of VLE predictive methods (as mentioned above) possible.
Section snippets
Materials
Carbon dioxide was purchased from Messer–Griesheim with a purity of 99.999 mol%, and naphthalene (>98% GC) and benzoic acid (>99.5% GC) from Fluka. All chemicals were used without further purification. Naphthalene and benzoic acid are solids at room temperature but liquids at the temperatures for which data were measured.
Equipment and procedure
A static magnetically stirred pressure cell [48] constructed from titanium and thermally regulated with a stability of ±0.1 K in a temperature controlled air-bath was used to
Results
The P–x data for CO2(1) + naphthalene(2) are presented in Table 2, the dew points in Table 3 and the P–x–(ycalculated) data are plotted in Fig. 1 along with the literature data at similar temperatures. A good agreement between the experimental data from the different sources and compared to the calculated data is obtained.
The P–x data for CO2(1) + benzoic acid(2) are presented in Table 4 and the P–x–(ycalculated) data are plotted in Fig. 2.
The Henry's constants for the CO2(1) + naphthalene(2) and CO2
Conclusions
In this work experimental P–x data and dew points are presented for naphthalene + CO2 and experimental P–x data are presented for benzoic acid + CO2 systems. Most of the isotherms measured are new data and improve the understanding of these systems. The data measured in this work will be used to refine and create parameters for predictive VLE methods such the PSRK group contribution EOS.
References (49)
- et al.
Multiphase behavior of binary and ternary systems of heavy aromatic hydrocarbons with supercritical carbon dioxide. Part I. Experimental results
Fluid Phase Equilib.
(1992) - et al.
Solubilities of methoxybenzoic acid isomers in supercritical carbon dioxide
Fluid Phase Equilib.
(1995) - et al.
Fundamental investigation on supercritical extraction of coal-derived aromatic compounds
J. Supercrit. Fluids
(1991) - et al.
Multiphase behavior of carbon dioxide with solid aromatics
Fluid Phase Equilib.
(1992) - et al.
Solubility of organic solid mixture in supercritical fluids
J. Supercrit. Fluids
(1996) - et al.
Solubility of dihydroxybenzene isomers in supercritical carbon dioxide
Fluid Phase Equilib.
(1998) - et al.
Extraction of uranium from solid matrices using modified supercritical fluid CO2
J. Supercrit. Fluids
(2001) - et al.
Measurement of copper compound solubility in supercritical carbon dioxide and correlation using a solution model
J. Supercrit. Fluids
(2002) - et al.
Phase equilibria of organic solid solutes and supercritical fluids with respect to the RESS process
J. Supercrit. Fluids
(2002) - et al.
A new simple static method for the determination of solubilities of condensed compounds in supercritical fluids
J. Supercrit. Fluids
(2002)