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The viability of an azeotropic distillation process using 2,2,4-trimethylpentane (isooctane) as an entrainer to dehydrate ethanol and obtain a mixture of ethanol + isooctane without water is analyzed utilizing both an experimental procedure and an equilibrium-model-based simulation. The direct manufacture of this mixture of ethanol + isooctane for use as gasoline should avoid the additional cost of dehydrating ethanol in an earlier process. Experimental results indicate that azeotropic distillation allows obtaining mixtures of isooctane + ethanol with water concentrations lower than 50 ppm. The results indicate that the most critical parameter for this process is the reboiler heat duty. Low values of this parameter (<2.2 kJ/g of feed ethanol) produce mixtures of ethanol + isooctane with excessive water contents. At high heat duty values (>3.6 kJ/g of feed ethanol) the azeotropic distillation column does not function properly, as the top stream condenses giving only one liquid phase. Results of the equilibrium-model-based simulation of the process yield results having a similar trend to the experimental ones. However, significant discrepancies are observed in some values, which could be attributed to the calculation of the liquid-liquid equilibrium. It is therefore necessary to improve the correlation of experimental equilibrium data of determined regions on the ternary system diagram.

Highlights-Vapor-liquid-liquid equilibrium data are determined-Vapor-liquid-solid and vapor-liquid-liquid-solid equilibrium data are determined-Results are compared with literature data-The influence of salt on water + 1-propanol equilibria is studied-The influence of temperature is also studied.

Liquid-liquid-solid equilibria for the ternary systems water-lithium chloride-1-propanol and water-lithium chloride-2-propanol at 25 °C have been measured experimentally. The equilibrium diagrams determined show differences between the two systems. In the system with 1-propanol, the solid phase of the liquid-liquid-solid region is monohydrated salt. However in the system with 2-propanol it is anhydrous salt.

Experimental isobaric vapor-liquid-liquid and vapor-liquid equilibrium data for the ternary system water (1) -cyclohexane (2) -isooctane (3) and the quaternary system water (1) -ethanol (2) -cyclohexane (3) -isooctane (4) were measured at 101.3 kPa. An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer was used to determine the VLLE. The results obtained show that the system does not present quaternary azeotropes. The point-by-point method by Wisniak for testing the thermodynamic consistency of isobaric measurements was used to test the equilibrium data.

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