Solubility of carbon dioxide in dimethylsulfoxide and N-methyl-2-pyrrolidone at elevated pressure

Abstract

Experimental data on the solubility of CO 2 in dimethylsulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP) are reported at temperatures of 298, 308 and 318 K and pressures approaching the mixture critical point for each binary system. The corresponding volumetric expansions of DMSO and NMP with CO 2 are also presented. The solubility data are correlated with the Peng–Robinson equation of state (PR-EOS). At a given temperature and pressure, higher solubilities of CO 2 are obtained in NMP compared with DMSO and this trend is consistent with the volumetric expansions of the solvents. A plot of the volumetric expansion data as a function of the solubility of CO 2 in the liquid phase suggests that it is unlikely, as a general rule, that the expansion isotherms for the various systems collapse onto a single expansion curve. The existence of a single expansion curve appears to hold only for a given binary system over a limited range of temperature. The use of two adjustable binary interaction parameters with the PR-EOS provides a superior correlation of the liquid phase composition in comparison with the standard PR-EOS, particularly in the vicinity of the mixture critical point.