Process for preparing 4-amino diphenylamine

Abstract

The present invention discloses production process of 4-amino diphenylamine with nitrobenzene and phenylamine as materials. For the condensation and hydrogenation, corresponding composite alkali catalyst and composite powdered catalyst are adopted separately. The production process includes the successive steps of condensation, separation I, hydrogenation, separation II and refining, and may be completed continuously. The composite alkali catalyst is separated and reused before the hydrogenation step, and this avoids the heat decomposition of the composite alkali catalyst and increases the catalyst selecting range. 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 present invention relates to the method for preparing 4-aminodiphenylamine, specifically, relate to using nitrobenzene and aniline as raw materials, using composite base catalyst as condensation catalyst, using conventional hydrogenation catalyst or composite powder catalyst as hydrogenation reaction catalyst, in Including condensation, hydrogenation, separation recovery and recycling of composite base catalyst and, if necessary, separation recovery and recycling of optionally at least partially regenerated composite powder catalyst, separation recovery and recycling of aniline and optional separation recovery and recycling of hydrogenation A method for continuously preparing 4-aminodiphenylamine in five processes of solvent and refining. 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 differen...

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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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