Separation of Glycerol from other Triols by Distillation

摘要

1,150,490. Glycerol, separation from other triols by distillation. KYOWA CHEMICALS K.K. 26 May, 1967 [28 May, 1966], No. 24673/67. Heading BIB [Also in Division C2] A mixture of glycerol with 1,2,3- and 1,2,4- butanetriols is submitted to steam distillation under reduced pressure and at a temperature not exceeding 200‹C, in order to obtain three separate fractions rich in glycerol, 1,2,3- BT and 1,2,4-BT, respectively. The mixture obtained by hydrogenolysis of sorbitol or mannitol is freed from ionic impurities by contacting it with ionic exchange resin, and the mixture is then dehydrated by distillation in a packed fractionating column. The dehydrated mixture is submitted to steam distillation under reduced pressure (50 mm.) in a second packed column, in order to remove glycols. The mixture is next steam-distilled at a temperature below 200‹C in a third column in order to separate unreacted hexitol as bottoms fraction, from as distillate comprising glycerol and the two specified butanetriols. This distillate is then submitted to steam distillation at a temperature not exceeding 200‹C in a fourth column in order to distil over a mixture of glycerol and 1,2,3-BT, leaving a residue comprising 1,2,4-BT admixed with glycerol. The distillate from the fourth column is steam-distilled in a fifth column to distil over the 1,2,3-BT traction; and the liquid withdrawn from the base of the fifth column is steamdistilled in a sixth column in order to obtain purified glycerol as distillate. The distillation-refsidue is advantageously recycled to the hexitol-removal column, the bottoms fraction of which is recycled to the hydrogenolysis system. In an alternative embodiment, the ,1,2,3-BT is removed from the glycerol before the 1,2,4-BT.