Prediction of multicomponent phase behavior of CO2-expanded liquids using CEoS/GE models and comparison with experimental data

Models utilizing cubic equation of state and excess Gibbs free energy-based mixing rules (CEoS/GE) were used for predicting the multicomponent VLE phase behavior involving CO2-expanded liquids. Four such models were selected out of 36 models (four CEoS in conjunction with nine mixing rules each) and evaluated with regard to their predictive capability using 14 systems, including 12 sub-systems (eight ternary systems, three quaternary systems and one quinary system) of 1-octene hydroformylation in CO2-expanded acetone (with the components H2, CO, CO2, 1-octene, n-nonanal, and acetone), a CO2-expanded toluene ternary system and a CO2-expanded acetonitrile ternary system. Model discrimination was based on their relative abilities to predict experimental VLE data generated within this work (ternary, quaternary or quinary systems with various combinations of H2, CO, CO2, 1-octene or n-nonanal) and from the literature. The results indicate that the CEoS/GE modeling approach is successful in predicting the phase behavior of the 14 investigated CO2-expanded liquid systems. The selected models are expected to be useful in the rational selection of CO2-expanded liquids and operating conditions (p & T) for optimal performance of reaction and/or separation units.