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Modeling
before for the fluorinated compounds. Figures III.20 and III.21 present the results obtained
for the CO2/benzene and CO2/toluene mixtures.
P / MPa
18
16
14
12
10
8
6
4
2
0
0 0.2 0.4 0.6 0.8 1
x, y CO2
P / MPa
18
16
14
12
10
8
6
4
2
0
0 0.2 0.4 0.6 0.8 1
x, y CO2
Figure III.20. Predictions of the vapor-liquid equilibrium of CO2/benzene system at 298, 313 and
353 and 393 K. Symbols represent experimental data. Solid lines correspond to the soft-SAFT
model including the polar term and dashed lines to the original soft-SAFT model. (a) Size and the
energy binary interaction parameters are set to one; (b) Size and the energy binary interaction
parameters adjusted at 313 K.
The full and dashed lines in Figure III.20a represent the predictions given by the
soft-SAFT EoS with and without the quadrupole moment respectively, setting the binary
interaction parameters equal to one. For the CO2/benzene mixture it is observed that the
inclusion of the quadrupole moment has again an important influence on the description of
the experimental results but is not enough to describe quantitatively the experimental data.
In the case of CO2/toluene mixture, the results in Figure III.21 show a similar behaviour as
observed for the CO2/benzene system. Contrary to the CO2/aromatic perfluoroalkanes, in
the case of the aromatic alkanes binary parameters have also to be adjusted to experimental
data. Results obtained when this is done are presented in Figures III.20b and III.21b. These
results agree with the ones obtained by Pfohl and Brunner (1998) who also had to consider
to binary interaction parameters to describe the CO2/toluene mixture when using an
extended SAFT EoS were the solvents are modelled by the BACK EoS.
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