A simple correlation to predict high pressure solubility of carbon dioxide in 27 commonly used ionic liquids

Engineers often demand the availability of easy correlations without difficult and time-consuming calculations. Up till now, there has been a lack of such correlations for mixtures of CO2 + ionic liquids. This work proposes a correlation to predict CO2 solubility in 27 common ionic liquids. The main advantages are its simplicity and minimal input data, namely temperature and pressure. The ionic liquids investigated ranged within a variety of families, having various anions and cations. Compared with the popular engineering models of Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK), the present correlation is much easier to use, yet it is also more accurate (PR, SRK and the proposed model had AARD% values of 43.5%, 44.3% and 4.9%, respectively for a total of 3073 data), even when binary interaction coefficients of PR and SRK are optimized to experimental data (AARD% values of 17.2%, 16.9% and 4.9% for PR, SRK and the proposed model, respectively).

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► A new correlation is proposed to predict CO2 solubility in ionic liquids.
► The correlation only requires system temperature and pressure as input.
► Constants of the equation are presented for 27 different ionic liquids.
► The results give an absolute average relative deviation of 4.9% for 3073 data points.
► The correlation is more accurate than Peng–Robinson and Soave–Redlich–Kwong equations.