Modeling cloud point of soluble polymers in supercritical carbon dioxide fluid using PCP-SAFT equation of state – An application in enhanced oil recovery

• The cloud point of the soluble polymers in supercritical carbon dioxide is investigated.
• Six types poly(lactic acid)–CO2 systems with the different molar masses and the end chemical groups are investigated.
• The PCP-SAFT EoS is used for calculation of the cloud point pressure.
• The quadrupole–quadrupole interaction between CO2 and polymer-segment is used.
• The phase behavior of the polymer–CO2 system is predicted well using the present EoS.

The phase behavior of the soluble polar polymers in supercritical carbon dioxide fluid has been already measured through determination of the cloud point pressure against the weight fraction of the polymer. In recent years, a few works have been carried out to investigate the solubility of some polar polymers in the supercritical carbon dioxide so that most of them have focused on the synthesis method of the polymers and measurements of their cloud point pressure. However, there is a lack of a proper thermodynamic model for prediction of the solution cloud point pressure of such systems. In this work, we model the cloud point pressure of the various types of poly(lactic acid) (PLA) with the different molar masses and end chemical groups; and various types of poly(1-O-(vinyloxy) ethyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranoside) (P(AcGlcVE)) with the different molar masses and the same end chemical groups. The Perturbed-Chain Polar Statistical-Associating-Fluid-Theory (PCP-SAFT EoS) of Gross, J. AIChE, 51 (2005) 2556–2568, is applied here through its modification for the present polymer–CO2 systems. We account the quadrupole–quadrupole term in the PC-SAFT EoS to represent the interaction energy between carbon dioxide molecules and polymer segments. Using the cloud point pressure data of the present polymer–CO2 systems, the parameters of the PCP-SAFT EoS are obtained for these polymers. The results show the present equation of state can correlate with the experimental cloud point data accurately so that the deviation of the experimental data with the calculated results is low.

The cloud point pressure for the polymer–CO2 supercritical system.Figure optionsDownload as PowerPoint slide