Rate-based simulation of a high pressure counter-current packed column for supercritical CO2 extraction of alcohol from dilute aqueous mixtures

In this work, the modeling and simulation of a fractionation packed column for the recovery of isopropanol from dilute aqueous mixtures using supercritical CO2 is presented. The model is based on the numerical resolution of differential mass balances for each component over the column height. The multicomponent mass transfer between phases is described using a "rate-based" approach and the concept of local mass transfer coefficients. The model was validated by reproduction of experimental steady-state results for the fractionation of 5% isopropanol aqueous solutions obtained in a bench scale counter-current column. The effect of process conditions on the separation performance was satisfactorily described by the model calculations, showing that operation pressure and CO2 flow rate enhance IPA recovery and extract purity, while operation temperature has a negative effect. Model deviations (AARD) were in all cases lower than 20%.