Method for catalytic degradation of hexachlorobenzene

Abstract

The invention discloses a method for catalytic degradation of hexachlorobenzene. The method comprises the following steps: firstly, filling a catalyst into a fixed bed reactor, and carrying out reduction treatment on the catalyst; secondly, mixing hexachlorobenzene steam and preheated hydrogen uniformly to obtain a mixed gas, introducing the mixed gas into the fixed bed reactor after reduction treatment, and carrying out catalytic hydrodechlorination reaction on the catalyst, thereby obtaining the mixed gas of benzene steam, hydrogen chloride gas and unreacted hydrogen; and thirdly, feeding the mixed gas of benzene steam, hydrogen chloride gas and unreacted hydrogen into a condenser for condensing, converting benzene into liquid, then feeding the hydrogen chloride gas and unreacted hydrogen in the mixed gas into an absorption tower for absorbing hydrogen chloride by ammonia water, compressing the unreacted hydrogen by a compressor, and returning for recycling. A solvent is not required to be added in catalytic hydrogenation and degradation of hexachlorobenzene by the method provided by the invention, benzene and ammonium chloride are produced as byproducts, and zero emission of pollutants can be reached, and the method is an environmental-friendly technology for degrading hexachlorobenzene efficiently.

Description

technical field [0001] The invention belongs to the technical field of catalytic hydrogenation, and in particular relates to a method for catalytically degrading hexachlorobenzene. Background technique [0002] Aromatic chlorides are widely used in industry, but they are toxic substances that endanger human health. Due to their high structural stability, they are difficult to degrade in nature. Therefore, researchers from all over the world are working hard to explore halogen-containing organic pollutants. efficient detoxification method. [0003] HCB is one of 12 persistent organic pollutants (POPs). Hexachlorobenzene has a completely symmetrical structure, and has many chlorine substitutions, high toxicity, and very difficult to degrade. According to the survey, at least 600 tons of hexachlorobenzene are produced in the domestic chemical production process every year, and the sealed hexachlorobenzene waste has the risk of leakage and diffusion, which poses a huge hidden ...

AI Technical Summary

Problems solved by technology

Hexachlorobenzene has a completely symmetrical structure, and has a large number of chlorine substitutions, high toxicity, and very difficult to degrade

According to the survey, at least 600 tons of hexachlorobenzene are produced in the domestic chemical production process every year, and the sealed hexachlorobenzene waste has the risk of leakage and diffusion, which poses a huge hidden danger to the safety of the surrounding ecological environment

Hexachlorobenzene is usually disposed of by simple incineration, which may produce dioxins during the incineration process, causing great harm to the environment

[0004] Dong Yuhuan and others prepared a new type of double-loaded bimetallic catalyst: PVP-PdCl2-MnXm / MontK10-PEG400, which uses the hydrogen transfer method to catalyze the dechlorination of hexachlorobenzene in the aqueous phase. The reaction conditions are mild and can make The conversion rate of hexachlorobenzene reaches 100%, but the catalyst preparation is too complicated, it is difficult to produce in large quantities, it is difficult to separate after the reaction, it is difficult to recover precious metals, and the reaction time is relatively long. The disposal amount of hexachlorobenzene is also less

[0005] Xiao Yong and others discussed the research progress of hexachlorobenzene degradation and removal methods in recent years. Scholars at home and abroad mainly carried out research on the degradation of hexachlorobenzene through the following methods, such as: photocatalytic oxidation, microbial degradation, irradiation method, Electrochemical method and catalytic hydrogenation method, these methods have a certain effect on the degradation of hexachlorobenzene, but most methods are still in the laboratory and theoretical research stage, due to various reasons and difficulties, there is no suitable method for practical application. Methods

[0006] Chinese patent 201010281630.2 invented a nickel phosphide catalyst for hydrodechlorination of chlorobenzene compounds, using a fixed bed reactor to achieve continuous dechlorination of chlorobenzene compounds with less than 3 chlorines, after catalyst modification The conversion rate has been improved and better results have been achieved. However, the Ni catalyst has certain insecurity, and the stability of the catalyst remains to be investigated.

In addition, the stability of hexachlorobenzene is high, and the catalyst is not necessarily suitable for the catalytic hydrodechlorination reaction of hexachlorobenzene

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