Distex process

Extractive rectification (Distex-process) [2.28, 2.29, 2.35, 2.36] is a distillation process which separates homogeneous, narrow boiling, or azeotropic liquid mixtures by the aid of an added substance of low volatility. The boiling point of the entrainer must be substantially higher than the boiling points of the components of the mixture. The less volatile component of the mixture selectively bonds to the entrainer, due to interactive forces. The vapor pressure of the less volatile component is therefore reduced and... 

Distillation with Extractive Solvents. Hydrocarbons of nearly the same boiling point (1 to 3°C) or constant-boiling mixtures cannot readily be separated by plain fractionation, and hence a combination of fractionation and solvent extraction known as the Distex process is employed. ... 

Distex A family of extractive distillation processes used in the petroleum industry from 1940. In one such process, furfural is used as the extracting agent for separating butadiene from other C4 hydrocarbons. 

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