PURIFICATION OF ACETIC ACID

摘要

1505336 Acetic acid MONSANTO CO 10 Aug 1976 [11 Aug 1975] 33207/76 Addition to 1343855 Heading C2C In a process for the purification of acetic acid from iodine containing components and water, a stream of acetic acid is introduced intermediate to a first distillation zone in which the major proportion of methyl iodide and water is removed overhead, a major proportion of hydrogen iodide is removed at the bottom and a stream from the mid-section is introduced to an upper section of a second distillation zone while a stream of methanol is introduced to the lower section of this zone. Pure acetic acid is removed at or near the bottom of this zone and the remainder of the water, methyl iodide and any methyl acetate formed is removed overhead. The acetic acid may be that prepared by reaction of an alcohol, ester, or ether and halide derivative with carbon monoxide with rhodium or iridium catalysts and an iodine or iodide compound promoter. The initial stream may be introduced to the lower third of the first zone and the withdrawn stream from the middle section may be introduced to the upper third of the second zone, while methanol is introduced to the lower fourth of the second zone. The overhead from the first zone may be separated to light and heavy phase and a portion of the light being refluxed to upper part of first distillation zone. The acetic acid may be removed as liquid or vapour from above the liquid at the bottom of the second zone.