Application of Isooctane to the Dehydration of Ethanol. Design of a Column Sequence To Obtain Absolute Ethanol by Heterogeneous Azeotropic Distillation

Consistent vapor−liquid (VLE) and vapor−liquid−liquid equilibrium (VLLE) data for the ternary system water + ethanol + isooctane (2,2,4-trimethylpentane) are reported at 101.3 kPa at temperatures in the range of 341−352 K. An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer has been used in the determination of the VLLE. The experimental data obtained demonstrates the existence of a ternary heterogeneous azeotrope at 68.7 °C with a composition of 0.198, 0.436, and 0.366 mole fractions of water, ethanol, and isooctane, respectively. The VLLE data were correlated simultaneously with VLE data by using the UNIQUAC model. The parameters obtained allow the development of suitable distillation sequences to obtain pure ethanol or a mixture of ethanol and isooctane.