Method for continuous hydrogenation preparation of 4-amino diphenylamine

Abstract

The present invention discloses a method for preparing 4-aminodiphenylamine by continuously hydronating condensate obtained from the reaction by using nitrobenzol and phenylamine as raw material and adopting compound powdered catalyst. i,e, adopts a catalyst and hydrogen gas circulation and solvent circulation combined new process to make the hydrogenation reaction be implemented under the condition of high-concentration, low-temp. and low pressure. The invented catalytic hydrogenation conversion rate can be up to 100%, and its selectivity is greater than 99%, and it is suitable for industrial production of 4-aminophenylamine.

Description

technical field [0001] The invention relates to a preparation method of 4-aminodiphenylamine, in particular to the preparation of 4-aminodiphenylamine by selecting a composite powder catalyst and a process flow and continuously hydrogenating a condensation liquid with nitrobenzene and aniline as raw materials. Background technique [0002] Using nitrobenzene and aniline as raw materials, 4-nitrodiphenylamine and 4-nitrosodiphenylamine or / and their salt condensation liquid can be prepared in the presence of a catalyst. In order to obtain 4-aminodiphenylamine, different reducing agents can be used to reduce 4-nitrodiphenylamine and 4-nitrosodiphenylamine or / and their compositions, such as iron (Fe) powder, alkali sulfide reduction, but these A common problem in the method is that the reaction conditions are harsh, the yield is low, there are many side reactions, and there are a lot of "three wastes" pollution; in addition, the traditional batch hydrogenation process, because e...

AI Technical Summary

Problems solved by technology

In order to obtain 4-aminodiphenylamine, different reducing agents can be used to reduce 4-nitrodiphenylamine and 4-nitrosodiphenylamine or / and their compositions, such as iron (Fe) powder, alkali sulfide reduction, but these A common problem in the method is that the reaction conditions are harsh, the yield is low, there are many side reactions, and there are a lot of "three wastes" pollution; in addition, the traditional batch hydrogenation process, because each step of the reactor must undergo pressure test, replacement, reaction and recovery The initial state and other processes, such repeated cumbersome operations, not only have high labor intensity and short catalyst life, but also require large investment in intermittent operations, low equipment utilization, and large hydrogen losses during operation. Switching operation under pressure will increase the fatigue strength of the hydrogenation reactor, thereby reducing the life of the reactor and affecting the smooth progress of production, so it is difficult to realize automatic production

In addition, in the existing hydrogenation reduction method using hydrogen, the catalyst raw materials used are expensive rare metals such as palladium (Pd), platinum (Pt), rhodium (Rh), which are not only rare in source, but also the catalyst is resistant to Poor toxicity and high production cost (see CN1307556A)

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