Method for refining 4-amino diphenylamine

Abstract

The present invention relates to a method for refining 4-aminodiphenylamine by adopting three-column continuous rectification and intermittent distillation. The crude product of 4-aminodiphenylamine can be obtained by rectification in the column No.1, and the substances of phenylamine, phenazine and azobenzene can be obtained at the top of column, said crude product can be purified in column No.2, in the column No.3 the phenylamine is separated, and the intermittent column can be used for making batch distillation of 4-aminophenylamine made up by using column bottoms of column No.2 and returning it into column No.2 for refining it. The yield rate of its whole process can be raised to 99% from 94%, and the content of 4-aminodiphenylamine in the finished product is greater than 99 wt%, at the same time the phenylamine can be recovered, and can be used.

Description

technical field [0001] The invention relates to a method for refining 4-aminodiphenylamine, in particular to a method for refining 4-aminodiphenylamine by three-tower rectification and intermittent distillation. Background technique [0002] 4-Aminodiphenylamine is an important intermediate compound of rubber antioxidant, and its quality directly affects the quality of downstream products. The existing method of distilling 4-aminodiphenylamine generally adopts simple distillation, the vacuum degree is 0.095MPa, the kettle temperature is 280°C-330°C, the top temperature is 220°C-240°C, and the heating adopts flue gas heating or far infrared Heating, using this method in the later stage of simple distillation, the temperature of the kettle is as high as above 300 ° C, and a large amount of coking is formed in the kettle at the same time, causing the product yield and quality of 4-aminodiphenylamine to decline; at the same time, using simple distillation, due to the theoretical...

AI Technical Summary

Problems solved by technology

If a simple distillation method is adopted, it is difficult to separate the above-mentioned components by distillation; if a two-tower distillation is adopted, the three materials of aniline, phenazine and azobenzene are discharged from the top of the front fraction tower, and 4-aminodiphenylamine is discharged from the top of the front fraction tower. The tower kettle is discharged, and then 4-aminodiphenylamine is continuously fed to the product tower, and the 4-aminodiphenylamine is discharged at the top of the tower, and the remaining materials are discharged at the tower kettle. The aniline in the raw material contains two substances, phenazine and azobenzene, and a large amount of aniline in the top of the product tower cannot be used mechanically back to the previous process, so the aniline cannot be recycled and used mechanically, resulting in waste of resources and increased production costs

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