Process for preparing dichlorohydrin

摘要

The invention relates to a process wherein a stream comprising dichlorohydrin, water, and HCI is separated into a stream which is rich in dichlorohydrin and low in HCI and an aqueous HCI stream which is low in dichlorohydrin. The process involves the distillation of the mixture comprising dichlorohydrin, water, and HCI with an amount of water being added before and/or during the distillation such that the water concentration during the distillation is on the line D-E, or to the right thereof, in the phase diagram of FIG. 1.

主权项

1. A process to make a dichlorohydrin-rich product, comprising:
a first step, wherein glycerin is reacted with HCl in the presence of a catalyst and optionally in the presence of a solvent; a second step, wherein the reaction mixture of the first step is separated into a light liquid stream comprising dichlorohydrin, water and HCl, and a stream of heavy compounds including the catalyst; and a distillation step wherein the light liquid stream is used as a crude mixture which is separated into a first product stream which is rich in dichlorohydrin and low in HCl, and a second product stream which is an aqueous HCl-containing composition low in dichlorohydrin, and wherein an amount of water is added before, during, or both before and during, the distillation step, with the molar amount of water which is added to 1 mol of the mixture (rH2O/crude) beingrH2⁢O/crude≥xDCH·crudexDCH·az⁡(DCH-H⁢⁢2⁢⁢O)+xHCl·crudexHCl·az⁡(HCl-H⁢⁢2⁢⁢O)-1 with xDCH.az(DCH—H2O) being the molar fraction of dichlorohydrin in (heterogeneous) azeotrope of binary system dichlorohydrin-H2O, xDCH.crude being the molar fraction of dichlorohydrin in the crude mixture, xHCl.az(HCl—H2O) being the molar fraction of HCl in (homogeneous) azeotrope of binary system HCl—H2O, and xHCl.crude being the molar fraction of HCl in the crude mixture.