Prediction of minimum miscibility pressure of pure CO2, carbon dioxide gas mixtures and polymer-supercritical CO2 in oil using modified quadrupole Cubic Plus Association Equation of State (mqCPA EoS)

Abstract

In this work, the modified quadrupole Cubic Plus Association Equation of State (mqCPA EoS) is used to predict the minimum miscibility pressure (MMP) of pure carbon dioxide, carbon dioxide gas mixtures and polymer-supercritical carbon dioxide (scCO2) systems with the different oils. Carbon dioxide is accounted as a quadruple molecule and by applying Ahmadi and Johns's algorithm, which is a multiple mixing cell (MMC) method, minimum miscibility pressures (MMP) for some scCO2-oil systems are predicted. Moreover, a specific parameterization work was performed so that the new binary interaction parameters, kij, were optimized for the hydrocarbon-CO2 pairs using mqCPA with the quadropolar term. For comparison of the present equation of state (EoS) with the common EoSs, the predictive Peng-Robinson 78 (PPR78) and Soave-Redlich-Kwong (SRK) are applied along with the binary interaction parameter correlations of the Pedesen and Xu et al. kij (Industrial & Engineering Chemistry Research, 54 (2015) 2816–2824). The obtained MMP values by mqCPA EoS are compared to the experiments and those obtained using the PPR78 and SRK EoSs. It is shown that the calculated results by mqCPA EoS demonstrate a good agreement with the experimental values, especially for injected of pure CO2 and leads to the better results in comparison with PPR78 and SRK EoSs. To predict MMP of the polymer-scCO2 systems, three types of poly(lactic acid) (PLA), three types of poly(1-O-(vinyloxy) ethyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranoside) (P(AcGlcVE)) and seven types of poly(vinyl acetate-alt-dibutyl maleate) (PVAc-alt-PDBM) are used. To our best knowledge, this is the first effort to predict the MMP of these polymer-scCO2-oil systems.