PART-STREAM DISTILLATION

摘要

A continuous process for the preparation of propylene oxide, comprising (a) reacting propene, optionally admixed with propane, with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent, obtaining a stream S0 containing propylene oxide, acetonitrile, water, at least one further component B, optionally propene and optionally propane, wherein the normal boiling point of the at least one component B is higher than the normal boiling point of acetonitrile and wherein the decadic logarithm of the octanol-water partition coefficient (log Kow) of the at least one component B is greater than zero; (b) separating propylene oxide from S0, obtaining a stream S1 containing acetonitrile, water and the at least one further component B; (c) dividing S1 into two streams S2 and S3; (d) subjecting S3 to a vapor-liquid fractionation in a fractionation unit, obtaining a vapor fraction stream S4 being depleted of the at least one component B; (e) recycling at least a portion of S4, optionally after work-up, to (a).

主权项

1. A continuous process for preparation of propylene oxide, the process comprising
(a) reacting propene with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent, obtaining a stream S0 leaving the reaction apparatus, S0 comprising propylene oxide, acetonitrile, water, at least one further component B, wherein a normal boiling point of the at least one component B is higher than a normal boiling point of acetonitrile and wherein a decadic logarithm of an octanol-water partition coefficient represented by log Kow of the at least one component B is greater than zero; (b) separating propylene oxide from S0, obtaining a stream S1 comprising acetonitrile, water and the at least one further component B; (c) dividing S1 into two streams S2 and S3, wherein a total weight of S3 relative to a total weight of S1 is in a range of from 0.01 to 25%; (d) subjecting S3 to a vapor-liquid fractionation in a fractionation unit, obtaining a vapor fraction stream S4 being depleted of the at least one component B, and obtaining a liquid bottoms stream S4b being depleted of acetonitrile; and (e) recycling at least a portion of S4.