Method for continuously synthesizing diphenylamine by utilizing phenylamine

Abstract

The invention discloses a method for continuously synthesizing diphenylamine by utilizing phenylamine. Phenylamine raw material contacts with hydrogen before entering into a reactor, the hydrogen is dissolved into the phenylamine raw material, the phenylamine raw material with the dissolved hydrogen enters into a reactor used for continuously synthesizing diphenylamine by virtue of phenylamine, the phenylamine raw material with the dissolved hydrogen passes through a catalyst bed layer, and a diphenylamine synthesizing reaction by virtue of the phenylamine is carried out, wherein the catalyst bed layer contains no gas-phase hydrogen. Compared with the prior art, the method disclosed by the invention has the advantage that the dissolved hydrogen substitutes for massive gas-phase recycled hydrogen while conversion rate of the reaction, selectivity of a target product and service life of a catalyst are guaranteed, so that equipment investment and operation energy consumption are greatly reduced, and reduction of production cost can be facilitated.

Description

technical field [0001] The invention relates to a method for continuously synthesizing diphenylamine in liquid phase with aniline as raw material in the presence of hydrogen and a solid catalyst. Background technique [0002] The traditional production method for synthesizing diphenylamine from aniline is a batch-type liquid-phase catalytic synthesis method. Since aluminum trichloride is used as a catalyst, the production equipment is severely corroded, polluted the environment, the reaction selectivity is low, and the separation of the catalyst and the product is difficult. The production process route Long, the unit consumption of raw materials is high, and the product cost is high. [0003] In order to overcome the shortcoming of above-mentioned synthetic technique, literatures such as US3118944, US4454348 adopt the vapor phase synthesis process of diphenylamine from aniline, use the solid catalyst of activated alumina as the main component, the reaction temperature is mo...

AI Technical Summary

Problems solved by technology

This method has the following disadvantages: (1) The loss of hydrogen is relatively large. One is that there will be a loss of about 30% in the pressure swing adsorption process; The separation process should have a loss of about 10%

(2) Due to the use of large-displacement hydrogen compressors and circulating compressors, the energy consumption is high, which reduces the profit of the product

The method is to use non-hydrogenation reaction. After a period of operation, it is found that although the non-hydrogenation reaction process is relatively simple and the energy consumption is also reduced, the following disadvantages are also brought about by the reaction without hydrogenation: (1) Reaction The conversion rate and selectivity both decreased; (2) The separation difficulty was also increased due to the decrease in selectivity; (3) The activity period (regeneration period) of the catalyst was correspondingly shortened

Although the process of continuous synthesis of diphenylamine from aniline has restored the characteristics of the hydrogenation reaction process after the above changes, it still has the following disadvantages: (1) The amount of hydrogen used in this reaction has not been reduced; (2) The hydrogen booster and hydrogen cycle Part of the energy consumption saved by the compressor is actually the result of the overall process optimization of the ammonia production unit and the diphenylamine production unit, and it is only to balance the energy consumption of the diphenylamine production unit to the upstream synthetic ammonia production unit; (3) This process The optimization results of the diphenylamine production unit will also be affected by the operation of the upstream synthetic ammonia production unit, and the independence of the operation of the diphenylamine production unit is obviously insufficient