REFINING METHOD FOR CRUDE PROPYLENE OXIDE PRODUCT AND PREPARATION METHOD FOR PROPYLENE OXIDE

摘要

A refining method for crude propylene oxide product and a preparation method for propylene oxide comprising the refining method. According to the refining method: a crude propylene oxide product is introduced into a first azeotropic distillation column and undergoes azeotropic distillation, the conditions of the first azeotropic distillation allowing most of the propylene oxide and part of the methanol from the material introduced into the first azeotropic distillation column to be collected in the form of an azeotrope from the top of the column, and allowing the remaining methanol and a small amount of the propylene oxide to be collected from the bottom of the column, the propylene oxide in the effluent from the bottom of the first azeotropic distillation column not exceeding 5% by weight; the azeotrope collected from the top of the first azeotropic distillation column is introduced into a second azeotropic distillation column and undergoes azeotropic distillation, the conditions of the second azeotropic distillation allowing most of the methanol and part of the propylene oxide from the compositions introduced into the second azeotropic distillation column to be collected in the form of an azeotrope from the top of the column, and allowing the remaining propylene oxide and a small amount of methanol to be collected from the bottom of the column, the methanol in the effluent from the bottom of the second azeotropic distillation column not exceeding 5% by weight; the azeotrope collected from the top of the second azeotropic distillation column is returned to the first azeotropic distillation column and undergoes azeotropic distillation with the crude propylene oxide product.