| 摘要 |
The components of a gaseous mixture containing acrylonitrile and ammonia and resulting from the vapour phase catalytic oxidation of propylene in the presence of ammonia and steam are separated by washing the mixture with an aqueous solution of an " organic acid " having a concentration sufficient to neutralize free ammonia and to produce a solution of the organic components of the mixture, distilling the aqueous solution so obtained under such conditions as to remove the organic components as an overhead distillate and an aqueous solution of substantially undecomposed ammonium salts of the organic acid as base product and thermally decomposing at least part of the base product to liberate ammonia and produce an aqueous solution of the free organic acid. The " organic acid " is one that is not easily entrained by water and the ammonium salts of which decompose on heating to produce ammonia and water. Specified acids are acetic and citric acids. The gases leaving the solution during the first distillation may be scrubbed with acid salt before condensation in the upper portion of the column and the components of the overhead fraction which include acrylonitrile, acrolein and acetonitrile may be separated by, for example, fractional distillation. The ammonia and steam distilled off during the decomposition of the ammonium salt may be recycled to the propylene oxidation and the aqueous organic acid remaining after said distillation may be recycled to the washing step.ALSO:The components of a gaseous mixture containing acrylonitrile, hydrocyanic acid and ammonia and resulting from the vapour phase catalytic oxidation of propylene in the presence of ammonia and steam are separated by washing the mixture with an aqueous solution of an "organic acid" having a concentration sufficient to neutralize free ammonia and to produce a solution of the organic compounds of the mixture, distilling the aqueous solution so obtained under such conditions as to remove the organic components, including hydrocyanic acid, as an overhead distillate and an aqueous solution by substantially undecomposed ammonium salts of the organic acid as base product and thermally decomposing at least part of the base product to liberate ammonia and produce an aqueous solution of the free organic acid. The "organic acid" is one that is not easily entrained by water and the ammonium salts of which decompose on heating to produce ammonia and water. Specified acids are acetic and citric acids. The gases leaving the solution during the first distillation may be scrubbed with acid salt before condensation in the upper portion of the column and the components of the overhead fraction may be separated by, for example, fractional distillation. |
