The 2,2,4-trimethylpentane + ethyl propanoate binary system: density, Bancroft point and vapor–liquid equilibrium at 30, 60 and 101.3 kPa

The 2,2,4-trimethylpentane (isooctane) – ethyl ethanoate binary system was experimentally investigated. The density of the mixture was measured using a vibrating-tube apparatus and is reported at temperatures T = (288.15, 298.15, 308.15 and 318.15) K. The mixture exhibits positive excess molar volumes. Isobaric vapor-liquid equilibrium (VLE) of the system were obtained at three pressures P = (30, 60 and 101.3) kPa. Pure components vapor pressures were also acquired over a range of P = (20 to 160) kPa. Equilibrium data were measured using a recirculation ebulliometer (Gillespie-type VLE cell).

The 2,2,4-trimethylpentane – ethyl ethanoate presents a Bancroft point within the investigated pressure range and, consequently, an azeotropic behavior at each studied pressure. The azeotropic coordinates, derived from the measured VLE data, are reported. A notable dependence of the azeotropic composition on pressure was observed.

The NRTL and Wilson activity coefficient models were used to correlate the VLE data. Temperature-dependent interaction parameters were determined, enabling precise correlation of the reported VLE data. The predictive UNIFAC (Dortmund) model was also tested. While it produced accurate results at 30 kPa, significant deviations were noted at higher pressures.