Recovery of butanol isomers from a mixture of butanol isomers, water, and an organic extractant

摘要

A process for recovering butanol from a mixture of a water-immiscible organic extractant, water, butanol, and optionally a non-condensable gas, is provided. The butanol is selected from 1-butanol, isobutanol, and mixtures thereof. An overhead stream from a first distillation column is decanted into two liquid phases. The wet butanol phase is refined in a second distillation column; the aqueous phase is returned to the first distillation column. A portion of the wet butanol phase from the decanter is also returned to the first distillation column. The extractant may be C7 to C22 fatty alcohols, C7 to C22 fatty acids, esters of C7 to C22 fatty acids, C7 to C22 fatty aldehydes, and mixtures thereof.

主权项

1. A process comprising the steps:
a) introducing a feed comprising:
(i) a water-immiscible organic extractant,(ii) water,(iii) at least one isomer of butanol, and(iv) optionally a non-condensable gas into a first distillation column, wherein the first distillation column comprises a stripping section and optionally a rectifying section at an introduction point above the stripping section, the first distillation column having an operating temperature, T1 and an operating pressure P1 at a predetermined point in the stripping section, wherein T1 and P1 are selected to produce a first bottoms stream and a first vaporous overhead stream, the first bottoms stream comprising the water-immiscible organic extractant and water and being substantially free of the at least one isomer of butanol, and the first vaporous overhead stream comprising water, the at least one isomer of butanol, and the optional non-condensable gas; b) condensing the first vaporous overhead stream to produce an optional gas phase and recover a first mixed condensate, wherein the first mixed condensate comprises
(i) a butanol phase comprising the at least one isomer of butanol and less than 30 wt % water; and(ii) an aqueous phase comprising water and less than 10 wt % of the at least one isomer of butanol; c) introducing at least a portion of the aqueous phase to the first distillation column; d) introducing a first portion of the butanol phase into a second distillation column having at least a stripping section; e) operating the second distillation column to produce a second bottoms stream comprising the at least one isomer of butanol and being substantially free of water, and a second vaporous overhead stream comprising the at least one isomer of butanol and water; and f) introducing at least a portion of the aqueous phase into a fermentation vessel, wherein the extractant is selected such that it (A) preferentially extracts the at least one isomer of butanol over water and (B) is separable from the at least one isomer of butanol by distillation.