Activity coefficients at infinite dilution of organic solutes in N-formylmorpholine and N-methylpyrrolidone from gas–liquid chromatography

Highlights: ► γ13∞ values reported for 25 organic solutes in the solvents NMP and NFM. ► Measurements undertaken using the glc technique at T = (333.2, 348.2, and 363.2) K. ► Measurements at elevated temperature possible by pre-saturation of carrier gas. ► Comparison of NMP and NFM performance with a number of solvents. -- Abstract: The infinite dilution activity coefficients for 25 solutes (n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes and alcohols) were measured in N-formylmorpholine (NFM) and N-methylpyrrolidone (NMP). This was performed using the gas–liquid chromatography (glc) technique with pre-saturation of the carrier gas. The solvents that were used had significant vapour pressures at the measured temperatures and therefore pre-saturation was necessary to mitigate against solvent loss from the column. Measurements were undertaken at three temperatures, viz. T = (333.2, 348.2, and 363.2) K. The selectivities and capacities for some industrial systems of interest, typically those which are quite difficult to separate via normal distillation, were calculated from the experimental results. The activity coefficients, selectivities and capacities are discussed and compared. The work was conducted to investigate the possibility of using the studied solvents in separating alkanes (such as cyclohexane) from aromatic compounds (such as benzene) and also separating aromatic compounds (such as benzene) from alkanols (such as methanol)