Measurement of Isobaric Vapor-Liquid Equilibria Necessary for Distillation Process Design Using Automatic VLE Apparatus

Vapor-liquid equilibrium is a key thermophysical property necessary for distillation process design. Tetrahydrofuran (THF) is produced by the dehydrocyclization of 1,4-butanediol. The key step in purification is breaking of the THF + water azeotrope. The n-paraffines like n-pentane, n-hexane and n-heptane are considered as the azeotropic solvents. The vapor-liquid equilibria for the systems containing THF are important for discussing the azetropic distillation process.

This paper deals with the measurement of bubble points for four binary systems, THF + water, + n-pentane, + n-hexane, + n-heptane at reduced pressure using automatic VLE apparatus. It is confirmed that THF + water and THF + n-hexane systems are azeotropic mixtures, though THF + n-pentane and THF + n-heptane are non-azeotropic mixtures. The NRTL parameters have been then determined using experimental bubble points. The NRTL parameters will be useful for discussing distillation process.