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

The use of butane-1,4-diol and glycerol as potential solvents for the extraction of heavy aromatics from higher alkanes was studied. An analytical method using a double-walled glass cell was used to perform liquid-liquid equilibrium (LLE) measurements for the systems n-nonane + o-xylene + (butane-1,4-diol or glycerol) at 298.2, 313.2, and 333.2 K and 0.1 MPa. Sample compositions at equilibrium were quantitatively determined with the use of gas chromatography. The temperature-dependent forms of NRTL and UNIQUAC models were used to correlate the tie-line data, producing low root mean square deviations. Ternary phase diagrams illustrated that the systems exhibit type II LLE behavior. Selectivity and capacity were calculated and used to evaluate the effectiveness of using these solvents in extraction applications for heavier diesel fractions. All selectivities were significantly higher than unity, indicating suitability of these solvents for this application. The capacity of glycerol was low, requiring further investigation into the use of cosolvents to be feasible on an industrial scale.