| 摘要 |
A process of refining crude acrylonitrile which has been prepared with an aqueous catalyst comprises subjecting the crude acrylonitrile to distillation or steam stripping while maintaining a pH not greater than 3, preferably 1 to 3. Any suitable acid or salt may be used for pH maintenance. The process may be applied to aqueous solutions or to dry or wet acrylonitrile. In the last two cases the pH is measured as 5% aqueous solution. In one example wet crude acrylonitrile containing HCN, acetaldehyde and lactonitrile is continuously acidified to pH 1.5 to 3 (measured as a 5% aqueous solution) with H3PO4 as it is fed to a three-column distillation train; free HCN and acetaldehyde are removed overhead in the first column, water is removed by azeotropic distillation in the second and purified acrylonitrile is distilled from the top of the third column; additional H3PO4 is added to the feed of the last two columns to maintain the pH at 1.5 to 3. Specification 591,945 is referred to.ALSO:A process of refining crude acrylonitrile which has been prepared with an aqueous catalyst comprises subjecting the crude acrylonitrile to distillation or steam stripping while maintaining a pH not greater than 3, preferably 1 to 3. Any suitable acid or salt may be used for pH maintenance. The process may be applied to aqueous solutions or to dry or wet acrylonitrile. In the last two cases the pH is measured as a 5% aqueous solution. In one example wet crude acrylonitrile containing HCN, acetaldehyde and lactonitrile is continuously acidified to pH 1.5 to 3 (measured as a 5% aqueous solution) with H3PO4 as it is fed to a 3-column distillation train; free HCN and acetaldehyde are removed overhead in the first column, water is removed by azeotropic distillation in the second and purified acrylonitrile is distilled from the top of the third column; additional H3PO4 is added to the feed of the last 2 columns to maintain the pH at 1.5 to 3. Specification 591,945 is referred to. |
