System for separating and reutilizing meta-position oil in nitrochlorobenzene production and meta-position oil separating method

Abstract

The invention provides a system for separating and reutilizing meta-position oil in nitrochlorobenzene production. The system comprises a first rectifying tower, an etherification device, a metering input device, a first dealcoholization kettle, a washing tank, a second rectifying tower and a third rectifying tower, wherein the metering input device is used for storing a sodium methylate solutionand is connected with a sodium methylate inlet so as to control the adding mode of the sodium methylate solution entering the etherification device. Meta-position oil is firstly subjected to rectification separation, and then p-nitrchlorobenzene and nitrochlorobenzene are fed into the etherification device for reaction; in an etherification step, due to the fact that the reaction activity of the sodium methoxide and p-nitrchlorobenzene are highest and the reaction activity of the nitrochlorobenzene is lower, sodium alkoxide is added by adopting a metering and continuously dropping way, excessive sodium methoxide for nitrochlorobenzene reaction is not provided, the sodium methoxide does not react with the nitrochlorobenzene, the way of converting the nitrochlorobenzene into other heavy component impurities is cut off, and the yield of the nitrochlorobenzene is ensured.

Description

technical field [0001] The invention relates to the technical field of nitrochlorobenzene production, in particular to a system for separating and reusing meso-oil in the production of nitrochlorobenzene and a method for separating meso-oil. Background technique [0002] During the generation of nitrochlorobenzene, a large amount of meta-oil is produced, that is, a mixture formed by p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene each accounting for about 1 / 3. The recovery of meta-oil When processing, some treat it as solid waste, and some use the principle of higher boiling point of o-nitrochlorobenzene to separate o-nitrochlorobenzene first by rectification, but p-nitrochlorobenzene and m-nitrochlorobenzene With a boiling point difference of 2°C, it is difficult to separate by rectification, which has also become a technical bottleneck. [0003] Some patents disclose the use of etherification methods to generate a mixture of p-nitroanisole and m-nitro...

AI Technical Summary

Problems solved by technology

But the problem that this patent exists is: sodium methylate solution is in etherification reactor, in order to make p-nitrochlorobenzene fully etherified, usually need to add excess sodium methylate solution, and this just exists excessive sodium methylate to be in p-nitrochlorobenzene At the same time as benzene reacts, it will also react with m-nitrochlorobenzene to produce heavy component impurities, so that m-nitrochlorobenzene cannot be fully and completely extracted, affecting the yield of m-nitrochlorobenzene and causing a waste of resources

Moreover, during the etherification reaction of this patent, an excess of sodium methoxide solution is also added to the etherification reaction kettle, so there is also an excess of sodium methoxide that will react with m-nitrochlorobenzene to produce heavy component impurities, so that m-nitro Chlorobenzene cannot be fully and completely extracted, which affects the yield of m-nitrochlorobenzene and causes waste of resources

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