GB929916A - Process for separation and purification of alkanols - Google Patents

Abstract

<PICT:0929916/III/1> A mixture of C2-C24 alkanols containing dissolved water, e.g.a. C2 to C10 mixture, obtained by the hydrolysis of complex aluminium alkoxides, is fractionated in a system essentially comprising two distillation columns 14 and 46 and an intermediary decanter 20. The mixture of alkanols enters the wash water tower 4 via line 2 and is mixed with a counter-current stream of hot water entering via line 7, using agitator 6. The hot water removes water-soluble impurities from the mixture of alkanols and leaves the tower via line 8. The wet mixture of alkanols from the tower is pumped via line 10 and heat exchanger 12 into the column 14, wherein the mixture is resolved into a dry bottoms product rich in heavy alkanols (C4 and above) and an overhead fraction containing substantial quantities of light alkanols (C2-C8) and water. The overhead fraction condenses in condenser 18 and passes into decanter 20. The water-rich phase 24 is recycled via line 26 into the wash-water feed line 7. The alkanol-rich phase 22 is pumped via line 42 and heat exchanger 44 into column 46, where it is separated by fractional distillation into an ethanol-water azeotrope, which is withdrawn from the condenser 48, and a C4-C8 alkanol fraction, which is pumped back to column 14 via line 50 to act as a reflux. The product rich in heavy alkanols drawn from the base of column 14, is pumped via line 28 into the fractionating column 30, where it is fractionated to yield an overhead product of butanol via line 32 and condenser 34, and a bottoms product of dry, heavy alkanols (C6 and above) which may be fractionated further if desired. Part of the butanol fraction is used as a reflux for column 30 via line 36, and part of it may also be returned to column 14 via line 40, for use as a reflux.ALSO:A complex mixture of alkanols, obtained in the oxidation and hydrolysis of complex aluminium alkyls produced by the reaction of simple aluminium alkyls, such as aluminium triethyl, with an olefin, such as ethylene, are separated and purified from water and accompanying salts by a process of fractional distillation in a system essentially comprising two distillation columns and an intermediary decanter to remove the water (see Group III). Example I gives details of the separation by this process of a mixture of ethanol, butanol, hexanol, octanol, decanol and water.