Modelling acid gas mixtures of polar aprotic solvents and CO2 with the Cubic Plus Association equation of state

Abstract

The Cubic Plus Association (CPA) equation of state and the Soave–Redlich–Kwong (SRK) equation of state coupled to Mathias–Copeman and volume correction parameters were used to correlate the vapor pressures and densities of pure polar aprotic solvents (PAS). It is shown that the CPA model (with 2B scheme) performed better than CPA (with inert scheme), SRK and its modifications in all cases for vapor pressure and densities. The performance of two mixing rules, namely the van der Waals one–fluid (vdW1f) and the Huron–Vidal (HV) mixing rules, is evaluated for these models on correlating the bubble–point pressures of CO2 + PAS mixtures. The CPA–HV model performs best at several temperatures, with the global average absolute deviations equal to 7.2 % for CPA–HV, 8.1 % for CPA–vdW1f and 8.7 % for SRK–HV. No improvements were found in the performance of the CPA–vdW1f when the solvation between CO2 and PAS was accounted for regression of bubble–point pressures.