Process for the separation by extractive distillation of cyclopentane from neohexane

摘要

Cyclopentane is separated from hydrocarbon mixtures which also contain neohexane by submitting the mixture to extractive distillation using, as extractant, a lower monoalkyl ether of ethylene glycol or an aqueous solution thereof; a solution of cyclopentane in the extractant is withdrawn from the base of the distillation column. In an example, a technical isohexane fraction obtained by fractional distillation of Venezuelan crude oil was distilled, and an azeotrope of cyclopentane and neohexane was collected. This azeotrope was fed as a vapour to the middle of a distillation column; and the monomethyl ether of ethylene glycol was introduced at a higher level in the column. The ratio by weight between the quantity of ether and the quantity of cyclohexane/neohexane mixture was 10 : 1. The overhead vapours comprised about 70 per cent neohexane and about 30 per cent cyclopentane by volume. A solution of cyclopentane in the ether was drawn off as bottom product which, on simple distillation, yielded cyclopentane having a purity of more than 99 per cent.