A kind of separation method of hydrogenation mixed liquor in the production of p-aminodiphenylamine

Abstract

The invention relates to the technical field of production of rubber antioxidant midbody, and particularly discloses a separation method of a hydrogenated mixture in the production process of p-aminodiphenylamine. The separation method is characterized in that hydrogenated mixed liquid is sent to a desolventizer tower to remove hydrogenation reaction solvent alcohol, and the rest mixed liquid is recovered from the tower bottom; the tower bottom mixed liquid is sent to an extraction separating tower, meanwhile an extraction solvent is melted in the tower, aniline and p-aminodiphenylamine in themixed liquid are extracted out to serve as an oil phase to be extracted from the tower top of the extraction tower, and a tetramethyl ammonium hydroxide water solution is extracted from the tower bottom; and the oil phase is sent to a distillation separation procedure, an extraction agent and aniline are steamed from the tower top respectively, and p-aminodiphenylamine is extracted out from the tower bottom. Compared with a traditional separation method, the separation method effectively improves the layering speed and the separation effect of the oil phase and a water phase, water consumption amount is small, the postprocessing difficult for recycling a condensation catalyst-tetramethyl ammonium hydroxide is reduced, consumption of the condensation catalyst is decreased, meanwhile the extraction agent is easy to recycle for cycle use, and the method is convenient and rapid, and economical and effective.

Description

[0001] (1) Technical field [0002] The invention relates to the technical field of production of rubber antioxidant intermediates, in particular to a method for separating a hydrogenated mixed liquid in the production of p-aminodiphenylamine. [0003] (2) Background technology [0004] The preparation reaction of p-aminodiphenylamine (RT-base), an important intermediate of p-phenylenediamine rubber antioxidant, is divided into two steps: first, aniline and nitrobenzene are condensed in the presence of a catalyst to form The condensation liquid of nitrodiphenylamine and p-nitrosodiphenylamine, the catalyst used in this step reaction is mainly a quaternary ammonium base phase transfer catalyst, such as tetramethylammonium hydroxide; then the condensation liquid is subjected to catalytic hydrogenation reaction to form The hydrogenation mixed solution containing p-aminodiphenylamine, in addition to the product-p-aminodiphenylamine, the mixed solution also contains aniline, a conde...

AI Technical Summary

Problems solved by technology

The disadvantages of this process are as follows: (1) In the process of oil-water separation, the phase difference between oil and water is small, the delamination speed is slow and the delamination effect is poor, and the phenomenon of water-in-oil and oil-in-water is serious, resulting in a large loss of phase transfer catalyst and product; (2) Washing and extraction consumes a lot of water, and the tetramethylammonium hydroxide is greatly diluted. With its continuous recycling, the concentration of tetramethylammonium hydroxide is so low that it cannot be recovered and can only be discharged from the system as waste liquid, which increases the The consumption of condensation reaction catalyst, (3) produces a large amount of waste liquid, which increases the difficulty and cost of post-processing