Purification of propylene oxide with aqueous acetone as a means of extraction distillation.

摘要

An impure propylene oxide feedstock contaminated with from about 50 to about 1000 ppm of methanol and from about 0 to about 1 wt. % of acetone is charged to the lower half of an extractive distillation column containing at least about 25 theoretical plates and an extractive distillation agent consisting essentially of a blend of acetone and water (acetone/water blend) containing about 20 to about 30 wt. % of acetone and, correspondingly, about 80 to about 70 wt. % of water is charged to the tower at a point 4 to 7 theoretical stages above the impure propylene oxide feed point; the extractive distillation agent being introduced into the extractive distillation column in the ratio of said feedstock to said extractive distillation agent of from about 5:1 to about 20:1, whereby an overhead distillate fraction is obtained consisting essentially of propylene oxide contaminated with not more than about 60 ppm of methanol, not more than about 0.02 wt. % of acetone and not more than about 0.3 wt. % of water.