| 摘要 |
1497970 Preparation of propylene oxide BAYER AG and DEUTSCHE GOLDUND SILBER - SCHEIDEANSTALT 27 Oct 1976 [24 July 1976] 44622/76 Heading C2C The invention comprises a process for the continuous preparation of propylene oxide from propylene and aqueous hydrogen peroxide wherein (a) an aqueous solution containing 10 to 45% by weight of a water-soluble acid catalyst and 20 to 35% by weight of hydrogen peroxide is reacted with propionic acid in a molar ratio of hydrogen peroxide: propionic acid of 0À8 to 1À5 : 1 or 3À5 to 5 : 1 at a temperature of from 10‹ to 70‹ C., (b) the resulting reaction mixture is extracted with benzene in countercurrent, (c) all or part of the aqueous raffinate from the extraction, which contains in the main hydrogen peroxide and acid catalyst, is reconcentrated by removing water by distillation, (d) the reconcentrated raffinate and the part of the raffinate which has optionally not been reconcentrated are recycled into the reaction stage (a), the concentrations of hydrogen peroxide and water-soluble acid catalyst being made up to those required for the reaction with propionic acid by adding the hydrogen peroxide required to restore the hydrogen peroxide concentration to that required for the reaction with propionic acid to the part of the raffinate which is to be reconcentrated, before or after removal of water by distillation according to (c), or to the part of the raffinate which is optionally not reconcentrated, (e) the benzene extract, which contains in the main perpropionic acid and propionic acid, is treated with water or an aqueous solution, (f) the solution, containing perpropionic acid and propionic acid, which is now obtained is reacted with excess propylene at a molar ratio of propylene to perpropionic acid of 1À2 to 6 : 1 at a temperature of from 50‹ to 90‹ C. and at a pressure of from 2 to 20 bars, and (g) the reaction mixture, containing propylene oxide, is worked up in a manner which is in itself known, pure propylene oxide being isolated and the excess propylene, the propionic acid and the benzene being recovered and the whole or part of these recovered products being recycled into the process. |
