O-chloroaniline preparation method

Abstract

The invention provides ano-chloroaniline preparation method, wherein the raw materials comprise: o-nitrochlorobenzene, a catalyst, dicyandiamide, a solvent, nitrogen and hydrogen. According to the invention, Ru/C is used as the catalyst, and has characteristics of simple components, stable activity and high selectivity, and dicyandiamide is used as the dechlorination inhibitor, so that the dechlorination side reaction is effectively inhibited, the conversion rate is high, and the selectivity is high; by improving the structure of the rectifying tower, the vapor-liquid mass transfer performancein heat transfer and mass transfer is improved, and the contact area between the gas phase and the liquid phases is increased by utilizing the auxiliary member; the turbulent flow degree is effectively increased through the inflow weir having the step structure and the turbulent flowblock, so that the mass transfer and heat exchange efficiency and the mass transfer and heat exchangerate between the gas phase and the liquid phases are improved; and the treatment and circulation capacities of the liquid phase are improved through the circulation tank, and the gas-liquid phase contact time is favorably prolonged by using the baffle arrangement of the downcomer and the inner diameter change, so that the yield and the purity of o-chloroaniline are improved.

Description

Technical field [0001] The invention relates to the technical field of fine chemicals, in particular to a preparation method of o-chloroaniline. Background technique [0002] O-Chloroaniline is an important class of fine chemical intermediates, widely used in the production of chemicals such as pesticides, medicines, dyes, and polyurethane industries. At present, the industrial production of o-chloroaniline uses o-nitrochlorobenzene as a raw material, and o-chloroaniline is prepared by a reduction method. The traditional nitro reduction methods include iron reduction, electrolytic reduction, alkali sulfide or hydrazine hydrate reduction methods. The insurmountable disadvantages are serious iron reduction pollution, high energy consumption of electrolytic reduction, and low yield of alkali sulfide reduction. These traditional methods are gradually being eliminated. Catalytic hydrogenation reduction method has received increasing attention due to its short reaction route, environ...

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Problems solved by technology

Traditional nitro reduction methods include iron reduction, electrolytic reduction, alkali sulfide reduction or hydrazine hydrate reduction reduction methods. The insurmountable disadvantages are that the iron reduction method is seriously polluted, the electrolytic reduction method has high energy consumption, and the alkali sulfide reduction method has a low yield. These traditional methods are gradually being phased out

The catalytic hydrogenation reduction method has been paid more and more attention because of its advantages such as short reaction route, environmental friendliness, good product quality, high yield, and recyclable catalyst. However, the catalytic hydrogenation reduction method has the following problems in the process of preparing o-chloroaniline : the one is prone to dechlorination reaction, which leads to equipment corrosion, product yield reduction, and catalyst activity reduction; the second is that in the rectification process of o-chloroaniline, because the existing trays generally have structural defects, resulting in In terms of heat transfer and mass transfer, the vapor-liquid mass transfer performance is not high, which affects the output and purity of o-chloroaniline

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