Method and device for producing p-phenylenediamine by using liquid phase continuous hydrogenation method

Abstract

The invention discloses a method and device for producing p-phenylenediamine by using a liquid phase continuous hydrogenation method. The reaction is carried out in first-stage and second-stage hydrogenation reaction kettles which are connected in series. The method comprises the following steps of: adding methanol which is 50-70% of the volume of the reaction kettles into the first-stage and the second-stage hydrogenation reaction kettles, adding a catalyst which is 0.5-1.5% of the methanol, and continuously introducing hydrogen into the first-stage and the second-stage hydrogenation reaction kettles in a stirring state; after reaching a certain pressure in the first-stage and the second-stage hydrogenation reaction kettles, continuously adding methanol and paranitroaniline into the first-stage hydrogenation reaction kettle, continuously keeping the pressure in the first-stage and the second-stage hydrogenation reaction kettles, meanwhile, discharging from the first-stage hydrogenation reaction kettle to the second-stage hydrogenation reaction kettle, and continuously discharging from the second-stage hydrogenation reaction kettle; recycling the catalyst from the reaction liquid from the second-stage hydrogenation reaction kettle through a settling tank; and removing methanol and water by rectifying the reaction liquid after the catalyst is recycled so as to obtain the p-phenylenediamine. The method and the device disclosed by the invention have the advantages of low cost, high yield, good safety and environment friendliness.

Description

technical field [0001] The invention relates to a production method and device for p-phenylenediamine, in particular to a method and a device for producing p-phenylenediamine by a liquid-phase continuous hydrogenation method. Background technique [0002] p-Phenylenediamine is one of the simplest aromatic diamines, and it is also a widely used intermediate, which can be used to prepare azo dyes, high molecular polymers, and can also be used to produce fur dyes, rubber antioxidants and photo In addition, p-phenylenediamine is a sensitive reagent commonly used to detect iron and copper. P-phenylenediamine is an extremely important dye intermediate, mainly used in aramid fiber, azo dyes, sulfur dyes, acid dyes, etc. At present, the main production process of p-phenylenediamine in China is obtained by reducing iron powder with p-nitroaniline as raw material. The disadvantages of this method are: the product yield is low, and the total yield is less than 85%; the environmental...

AI Technical Summary

Problems solved by technology

The disadvantages of this method are: the product yield is low, and the total yield is less than 85%; the environmental pollution is serious, and the iron sludge generated is difficult to handle; the operating environment is poor

[0003] There are also domestic reports on the production of p-phenylenediamine by catalytic hydrogenation, but all of them are produced by batch method. The production capacity of batch method equipment is low, and the operation labor intensity is high. During the production process, the reactor needs to be replaced by hydrogen, which leads to high hydrogen consumption and poor safety.

Images