Benzene or toluene separation from mixts. - by azeotropic-extractive distillation using DMF as solvent giving reduced solvent loss

摘要

The separation of benzene and/or toluene from mixts. with >=1 cycloalkane or paraffin hydrocarbon comprises extractive distn. in a distn. zone in presence of an extn. solvent of an aliphatic N-alkylamide with the aim of reducing the solvent losses entrained in the distillate. Water is introduced into the section of the distn. zone between the point of injecting the extn. solvent and the head of the distn zone in a quantity and under conditions such that it is evaporated within that part of the distn. zone without diluting the solvent. The vapours given off at the head are condensed and the condensate sepd. into two liquid phases, the first consisting of the satd. hydrocarbons, and the second mostly condensed water vapour. There is no solvent loss at the head of the distillation column and automatic control of water flow in all working conditions is obtd.