Study of Methanol Extraction from Saturated Alkanes: Solvent Screening, Liquid-Liquid Equilibrium Measurement, and Thermodynamic Simulation

In the process of CO2 catalytic hydrogenation to methanol, saturated alkanes will be produced, and the purity of refined methanol will be reduced. Therefore, the separation of methanol from saturated alkanes is very important. The separation of methanol and saturated alkanes was studied in this work. The suitable solvent was screened by s-profile analysis, interaction energy analysis, and extraction performance analysis. Finally, ethylene glycol was selected as the suitable solvent for the separation of methanol from saturated alkanes. The liquid-liquid equilibrium (LLE) data of {n-hexane, n-heptane, iso-octane, and n-nonane} + methanol + ethylene glycol were measured at 303.2 K and 101.3 kPa, respectively. The extraction performance of ethylene glycol was evaluated by distribution constant (D) and separation factor (S). In the meantime, LLE data were regressed using the nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) models to obtain the regression parameter values. The root-mean-square deviation (RMSD) of the NRTL and UNIQUAC models were less than 0.0047 and 0.0044, respectively.