PROCESS FOR THE SEPARATION AND PURIFICATION OF A MIXED DIOL STREAM

摘要

Disclosed is a process for the purification of a mixed diol stream. The mixed diol stream comprising two-, three-, and four-carbon diols is separated into component diols by extraction with a hydrophobic solvent mixture. The diols recovered in the extractant may be removed from the extractant stream by back extraction with water or by distillation with an azeotrope-forming agent present, preferably an azeotroping agent already present in the extractant mixture.

主权项

1. A process for recovering diols from a mixed diol stream, comprising
(A) extracting said mixed diol stream, comprising
(i) 0.1 weight percent to 50 weight percent of one or more diols selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol;(ii) 5 weight percent to 90 weight percent glycerol; and(iii) 5 weight percent to 90 weight percent water; each based on the total weight of said mixed diol steam stream, with an extractant, comprising(i) a hydrophobic solvent selected from alkanols having from 6 to 20 carbon atoms, ketones having from 5 to 20 carbon atoms, esters having from 5 to 20 carbon atoms, ethers having from 5 to 20 carbon atoms, carboxylic acids having from 5 to 20 carbon atoms, trialkylphosphine oxides having from 18 to 48 carbon atoms, and mixtures thereof; and(ii) optionally, a second modifying hydrophobic solvent selected from hydrocarbons having from 5 to 20 carbon atoms; to form a raffinate phase comprising a major amount of said glycerol and a minor amount of said diols contained in said mixed diol stream and an extract phase comprising a major amount of said diols and a minor amount of said glycerol contained in said mixed diol stream; and (B) separating said raffinate phase and said extract phase.