Washing and separation method of nitrobenzene

Abstract

The invention relates to a washing and separation method of nitrobenzene. The washing and separation method of nitrobenzene includes allowing nitration product and waste acid to enter a nitrifying separator for separation when nitration is over, allowing organic phase to enter a coalescing separator after separation to further remove the waste acid in the organic phase, subjecting the organic phase to alkaline cleaning and water washing in two centrifugal extractors respectively, and subjecting the obtained organic phase to post-treatment. The coalescing separator can be static separators such as a fiber-cartridge separator, a plate separator or a combined separator. Organic phase and inorganic phase are reversely mixed in the centrifugal extractors. The waste acid in the crude nitrobenzene can be further removed by water washing and separation by the method, and alkaline consumption in neutralization is lowered. The centrifugal extractors are used in neutralization and washing, and accordingly no additional neutralization and washing separator is needed, and floor area of equipment is reduced. Mixing effect is fine, washing is sufficient, content of phenoxide in the washed crude nitrobenzene is lower, and safety of a production system is improved.

Description

technical field [0001] The invention relates to a production method of chemical products, in particular to a production method of deacidification and dephenolization of crude nitrobenzene in the production process of nitrobenzene by nitration of benzene. Background technique [0002] The crude nitrobenzene produced by benzene under the action of mixed acid contains residual acid and nitrophenol by-products that will bring danger to subsequent production. The nitrobenzene washing process is to use a certain concentration of lye to neutralize the residual liquid in the crude nitrobenzene and make the nitrophenols react with the alkali to form phenoxide. The phenate is easily soluble in water, and then washed with water to achieve the purpose of deacidification and dephenolization. The above-mentioned production process is customarily called a nitrobenzene washing process. After washing, the organic phase and the inorganic phase need to be separated. The inorganic phase is was...

AI Technical Summary

Problems solved by technology

This production method has a large number of equipment, high investment, large floor area, high energy consumption, complicated operation and control, and difficult to guarantee the washing effect.

[0004] The second is multi-injector series jet washing. Jet washing has good deacidification and phenol removal effects, but the operation flexibility is small, and it cannot be operated within a wide output range. In addition, jet washing relies on high-speed flowing water and alkaline water. To pump crude nitrobenzene, so the water consumption is large, the energy consumption is high, and a separator must be installed after each stage of spraying; in addition, spray washing is easy to emulsify water and washings

Compared with the kettle-type series washing, the tubular scrubber is a static device, which saves energy and water consumption. The main problem is that the mixing effect of the tubular scrubber is not ideal, resulting in the sodium and phenol salts in the crude nitrobenzene The content is too high, and a larger wastewater separator is still required, which occupies a larger area

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