Process for preparing 4-amino diphenylamine

Abstract

The present invention discloses production process of 4-amino diphenylamine with nitrobenzene and phenylamine as materials. The production process includes five steps of condensation; hydrogenation; separating, recovering and reusing composite alkali catalyst, and separating, recovering and reusing at least partial regenerated composite powdered catalyst; separating, recovering and reusing phenylamine and hydrogenation solvent; and refining. For the condensation and hydrogenation, composite alkali catalyst and composite powdered catalyst are adopted separately. The production process has mild reaction condition and less side products, may be completed continuously, and is suitable for industrial production. The production process has 4-amino diphenylamine yield industrial scale over 95 % and 4-amino diphenylamine purity over 99 wt%.

Description

technical field [0001] The invention relates to a method for preparing 4-aminodiphenylamine, in particular to a method for continuously preparing 4-aminodiphenylamine by using nitrobenzene and aniline as raw materials, using two composite catalysts and a cyclic operation process flow. Background technique [0002] 4-Aminodiphenylamine is an important antioxidant and stabilizer intermediate, and an important chemical product in the rubber industry and polymer industry. According to the different raw materials used, the current methods of producing 4-aminodiphenylamine are: (1) the aniline method, using p-nitrochlorobenzene and aniline as raw materials, reacting under the action of a catalyst to generate 4-nitrodiphenylamine, and then using vulcanization Alkali reduction to 4-aminodiphenylamine; (2) formanilide method, using formic acid and aniline as raw materials to prepare formanilide, and then reacting with p-nitrochlorobenzene in the presence of an acid-binding agent (suc...

AI Technical Summary

Problems solved by technology

There are some common disadvantages in these methods: one is that the selected catalyst is expensive, and the application to industrial scale production will cause the production cost to be too high, and there is no advantage compared with the current production process

In this patent, it is necessary to have a solvent and control the content of the proton material in the solution. The introduction of the solvent brings increased energy consumption and difficulty in separation. Controlling the proton material brings difficulty to the reaction control, especially in the condensation reaction. In the later stage, controlling the content of the proton material in the solution (mainly refers to dehydration to a relatively small content) will prolong the reaction time and take away part of the aniline. The range operation is difficult, which is not conducive to industrial production; when the proton material is controlled in the range of 0.5-4%, the expensive tetraalkyl quaternary ammonium base catalyst will be decomposed rapidly, resulting in increased production costs

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