Ternary Liquid–Liquid Equilibrium Data for the n-Heptane + Toluene + (Butane-1,4-diol or Glycerol) Systems at 298.2, 313.2, and 333.2 K and 0.1 MPa

Abstract

Liquid–liquid equilibrium (LLE) phase compositions (tie-line data) were experimentally measured and thermodynamically modeled for the systems n-heptane + toluene + (butane-1,4-diol or glycerol) at 298.2, 313.2, and 333.2 K and 0.1 MPa. The direct analytical method was used to obtain the LLE data using a double-walled glass cell. The phase equilibrium samples were quantitatively analyzed using gas chromatography. The ternary systems were successfully correlated using the NRTL and UNIQUAC thermodynamic models. The effectiveness of using butane-1,4-diol or glycerol as an alternative solvent to extract toluene from alkanes was evaluated by determining selectivity and solvent capacity. All systems studied were found to demonstrate type II ternary LLE behavior. The selectivity for the solvents studied was found to be comparable or superior to conventional solvents, but solvent capacities were poor, suggesting that the use of a cosolvent might be required to reduce solvent-to-feed ratios.