O-phenylenediamine medium-pressure catalytic hydrogenation process

Abstract

The invention discloses an o-phenylenediamine medium-pressure catalytic hydrogenation process which is characterized by comprising the following steps: adding ortho-nitroaniline as a raw material, water as a solvent and 5% of palladium-carbon as a catalyst into a pressure kettle, repeatedly replacing the air inside the kettle through nitrogen, subsequently emptying the kettle, further repeating the replacement by using hydrogen, after the replacement is accomplished, raising the temperature, heating, reacting for 2 hours, after the reaction is accomplished, keeping the pressure, reacting for 0.5 hour, after the reaction is accomplished, cooling down, replacing the hydrogen inside the kettle by using nitrogen, discharging the material in hot, filtering the catalyst for further application, cooling down the filtrate to separate out crystal, cooling down and filtering to obtain a product, namely, the o-phenylenediamine, refeeding the filtrate into a next batch for being used as process water for repeated circulation. The further application situation of the catalyst is good, the reaction temperature is low, the pressure is small, the synthesis cost is greatly lowered, and in addition the process water is repeatedly applied, and the wastewater is discharged for only once after the process water is applied for multiple times, so that the water pollution is greatly reduced.

Description

technical field [0001] The invention relates to a process for preparing o-phenylenediamine, in particular to a process for preparing o-phenylenediamine through medium-pressure catalytic hydrogenation. Background technique [0002] O-phenylenediamine is a white crystalline solid. It is an important fine chemical intermediate. It is mainly used as a pesticide intermediate. It is the raw material for carbendazim and thiophanate-methyl. It is also a dye intermediate for the production of cationic dyes and Vat dyes can also be used to produce rubber antioxidants, fur dyes, developers and surfactants. [0003] At present, there are many industrial synthesis methods of o-phenylenediamine, and there are many synthetic routes and methods: mainly including alkali sulfide reduction and catalytic hydrogenation. Although the production process of alkali sulfide reduction is simple, the product yield is low and the cost is high. In particular, the large amount of waste water and residue ...

AI Technical Summary

Problems solved by technology

Although the production process of alkali sulfide reduction is simple, the product yield is low and the cost is high. In particular, a large amount of waste water and residue generated is difficult to handle, and the environmental pollution is quite serious. It will gradually face the trend of being eliminated in the future; catalytic hydrogenation to prepare o-phenylenediamine The advanced technology has the advantages of good product quality, high yield, and less "three wastes", but it needs to add expensive catalysts in the preparation process, which cannot be applied mechanically, and the production cost is high