Method for preparing m-phenylenediamine based on continuous catalytic hydrogenation of fixed bed microreactor

Abstract

The invention discloses a method for preparing m-phenylenediamine based on continuous catalytic hydrogenation of a fixed bed microreactor, which comprises the following steps: (1) taking dinitrochlorobenzene as a raw material, and dissolving the dinitrochlorobenzene in a solvent to serve as a to-be-hydrogenated substrate solution, wherein the dinitrochlorobenzene is at least one of 2, 4-dinitrochlorobenzene, 2, 6-dinitrochlorobenzene and 3, 5-dinitrochlorobenzene; (2) mixing a to-be-hydrogenated substrate solution and hydrogen in a micro-mixer to form a gas-liquid mixture with a good gas-liquid micro-dispersion state, and then enabling the gas-liquid mixture to enter a micro-packed bed reactor filled with a solid particle catalyst to react, wherein the reaction temperature is 40-160 DEG C, and the pressure is 1-5 MPa, and the retention time of the gas-liquid mixture in the micro-packed bed reactor is 10-120 s; and (3) carrying out gas-liquid separation on a gas-liquid mixture obtained after the reaction is finished, and feeding a liquid product into a subsequent separation and purification system.

Description

technical field [0001] The invention relates to the technical field of preparing m-phenylenediamine, in particular to a method for preparing m-phenylenediamine based on continuous catalytic hydrogenation of a fixed-bed microreactor. Background technique [0002] M-phenylenediamine is an important organic chemical raw material and intermediate, which is widely used in the dye industry in the synthesis of azo dyes, fur dyes, reactive dyes and sulfur dye intermediates, and can also be used to prepare hair dyes, Color developer, petroleum additives and cement coagulant and other materials. M-phenylenediamine can also be synthesized with phthaloyl chloride to prepare high-temperature-resistant aromatic polyamide resin and flame-retardant fiber, which are used in special fields such as national defense and aerospace. At present, the synthesis methods of m-phenylenediamine mainly include iron powder reduction method, electrolytic reduction method and catalytic hydrogenation method...

AI Technical Summary

Problems solved by technology

However, there are following defects in the preparation of m-phenylenediamine by hydrogenation of dinitrochlorobenzene in a hydrogenation kettle: the catalytic hydrogenation reaction of dinitrochlorobenzene is a typical gas-liquid-solid three-phase reaction, and when reacting in a batch kettle, In order to ensure the full contact between the three phases and the full progress of the hydrogenation reaction, high pressure and long reaction time are usually required, and the reaction efficiency is low. At the same time, the low mass transfer and reaction efficiency will lead to azo compounds and non-dechlorination The generation of by-products will have a great impact on the purity of the product. The post-treatment process is complicated, and 5% to 10% of the catalyst needs to be added after each reaction, which greatly increases the production cost.

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