Method for producing phenylenediamine by solvent-free hydrogenation continuous reaction of dinitrobenzene

Abstract

The invention provides a method for producing phenylenediamine by solvent-free hydrogenation continuous reaction of dinitrobenzene, which is used for preparing phenylenediamine by continuous hydrogenation reaction of dinitrobenzene as a raw material, and comprises the following steps of: S1, adding water, phenylenediamine and a catalyst into a hydrogenation reactor, and mixing; S2, introducing nitrogen into the hydrogenation reactor, then circularly introducing hydrogen for replacement and pressure rise, and raising the temperature; and S3, continuously adding dinitrobenzene into the hydrogenation reactor, and carrying out a hydrogenation reaction. According to the method for producing phenylenediamine through solvent-free hydrogenation continuous reaction of dinitrobenzene, the yield of phenylenediamine is greatly increased through continuous hydrogenation reaction.

Description

technical field [0001] The invention belongs to the field of chemical synthesis, and relates to a method for producing phenylenediamine through solvent-free hydrogenation continuous reaction of dinitrobenzene. Background technique [0002] Phenylenediamine is an important raw material for organic synthesis, mainly including three isomers (m-phenylenediamine, o-phenylenediamine and p-phenylenediamine), widely used in the manufacture of azo dyes, oxazine dyes and reactive dyes. Phenylenediamine is mainly obtained from dinitrobenzene by hydrogenation and purification. [0003] The existing public method: using methanol or ethanol as a solvent, mixing water, methanol and catalyst in a certain proportion in a continuous full-mixed flow hydrogenation reactor, at a temperature of 95-105 ° C and a gauge pressure of 2.0 MPa, the hydrogenation reaction Dinitrobenzene is continuously put into the reactor, and the reducing liquid obtained after the reaction of dinitrobenzene and hydro...

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Problems solved by technology

[0004] Due to the need to use methanol or ethanol as a solvent in the reaction, the method requires high material consumption and energy consumption in the process of solvent separation and recovery; under reaction conditions, methanol or ethanol can also alkylate the generated phenylenediamine, thereby reducing Yield of phenylenediamine

[0005] In addition, the invention patent with publication number CN110467534A discloses a process for synthesizing phenylenediamine by solvent-free catalytic hydrogenation of dinitrobenzene. The process adopts discontinuous reaction, and the concentration of dinitrobenzene in the reaction vessel is too high, resulting in There are many side reactions, the catalyst is easily deactivated, and the product yield is low

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