Phase equilibria in systems composed of an aliphatic and an aromatic hydrocarbon and sulpholane

Ternary liquid‐liquid equilibria of the type aromatic + non‐aromatic + sulpholane were studied. The systems cyclohexane + benzene + sulpholane, 1‐hexene + benzene + sulpholane, hexane + benzene + sulpholane and heptane + toluene + sulpholane were experimentally determined at 25, 50, 75 and 100°C. The binary vapour‐liquid equilibria sulpholane + benzene and sulpholane + toluene were also measured. The ternary data were correlated by means of the NRTL‐equation with 6 and 9 variable parameters. To overcome correlating problems the starting values of the parameters were taken from the corresponding binary liquid‐liquid and vapour‐liquid equilibria, and were varied two by two. Use of 9 parameters did not improve significantly the correlation. Generally the bottom tielines are correlated very well, while at the top considerable deviations can occur.