Recovery of alkylene glycols
AssigneeHalcon International, Inc.
InventorChun Fei Chueh
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Abstract
Ethylene glycol or 1,2-propylene glycol contained in mixtures with lower carboxylate esters of the glycol is recovered by azeotropic distillation of the mixtures with an azeotroping agent forming a minimum boiling azeotrope with the ethylene glycol or the 1,2-propylene glycol, the distillation being effected with reflux of azeotroping agent as well as controlled reflux of the glycol to the distillation zone.
Claims11
A process for recovering ethylene glycol or propylene glycol from a mixture comprising propylene glycol or ethylene glycol in admixture with at least one of a mono-lower carboxylate ester and a di-lower carboxylate ester of said propylene glycol or ethylene glycol which comprises the steps of:
- a. subjecting said mixture to distillation in a distillation zone in the presence of an azeotroping agent effective to form a minimum-boiling azeotrope with said glycol, said azeotroping agent being essentially water and glycol immiscible and having a boiling point at atmospheric pressure of above 135.degree. to about 220.degree. C, whereby an overhead product and a bottoms product are produced, said overhead product comprising said azeotroping agent and said glycol and said bottoms product comprising said ester substantially reduced in glycol content;
- b. separating said overhead product into a first phase comprising said azeotroping agent and a second phase comprising said glycol;
- c. returning said first phase to said distillation zone as reflux;
- d. supplying a portion of the glycol as reflux to said distillation zone;
- and
- e. withdrawing the remainder of the glycol from said second phase as glycol product, wherein the ratio of the glycol supplied to the glycol withdrawn is at least 0.3:1.
Dependencies are inferred from the claim text.