Prediction of Ionic Liquid Properties. II. Volumetric Properties as a Function of Temperature and Pressure

The density of ionic liquids (ILs) as a function of pressure and
temperature has been modeled using a group contribution model. This
model extends the calculations previously reported (Jacquemin et al. J. Chem. Eng. Data 2008) which used 4000 IL densities at
298.15 K and 600 IL densities as a function of temperature up to 423
K at 0.1 MPa to pressures up to 207 MPa by using described data in
the literature and presented in this study. The densities of two different
ionic liquids (butyltrimethylammonium bis(trifluoromethylsulfonyl)imide,
[N1114][NTf2], and 1-butyl-1-methyl-pyrrolidinium
bis(trifluoromethylsulfonyl)imide, [C4mPyrro][NTf2]) were measured as a function of temperature from (293 to 415) K
and over an extended pressure range from (0.1 to 40) MPa using a vibrating-tube
densimeter. The model is able to predict the ionic liquid densities
of over 5080 experimental data points to within 0.36 %. In addition,
this methodology allows the calculation of the mechanical coefficients
using the calculated density as a function of temperature and pressure
with an estimated uncertainty of ± 20 %.