Continuous ammonia neutralization process of 2-methyl-5-nitroimidazole nitration completion liquid

Abstract

The invention discloses a continuous ammonia neutralization process of 2-methyl-5-nitroimidazole nitration completion liquid. The method comprises the following steps of: respectively conveying nitration reaction completion liquid diluted by water and ammonia water solution for neutralization to a T-shaped mixer by a steady flow conveying metering pump, and carrying out instantaneous mixing and instantaneous neutralization reaction, wherein the flow ratio of the nitration reaction completion liquid to the ammonia water solution for neutralization is subjected to linkage closed-loop regulation through the PH value of the mixed feed liquid in the crystallization kettle; after mixing is completed, entering the crystallization kettle for crystallization; and then, carrying out separation, washing and drying to obtain a finished product. The method has the advantages that the continuous ammonia neutralization of the nitration reaction completion liquid of the 2-methyl-5-nitroimidazole is realized, and the production efficiency is greatly improved; after the neutralized and washed product is dried, the appearance is whiter, and the quality is better; meanwhile, the yield of the product 2-methyl-5-nitroimidazole in the neutralization process is increased by 99.8% or above; and compared with the traditional intermittent neutralization process, the water consumption can be saved by more than 30%.

Description

technical field [0001] The invention relates to a continuous ammonia neutralization process of 2-methyl-5 nitroimidazole nitration completion liquid, which belongs to the technical field of micro-reaction. Background technique [0002] After the nitration reaction of 2-methyl-5 nitroimidazole is completed, it is necessary to neutralize the nitration reaction completed liquid with ammonia water to a pH value of 3 to 5, after neutralization, 2-methyl-5 nitroimidazole crystallizes out from the liquid phase, Thereby realize the separation of finished product 2-methyl-5 nitroimidazole. However, whether the current ammonia neutralization process is a traditional tank-type nitration process or a micro-reaction nitration process, the ammonia water neutralization process is to add ammonia water dropwise into the tank containing the nitration reaction completion liquid diluted with water under stirring conditions. This process is a batch operation process. [0003] Practice has foun...

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Problems solved by technology

[0004] 1. The neutralization process is intermittent, the neutralization process takes a long time, and the production efficiency is low

[0005] 2. In the later stage of neutralization, since a large amount of 2-methyl-5 nitroimidazole crystals have been precipitated from the liquid phase, the entire liquid phase is relatively thick, and it is difficult for the ammonia water newly added to the neutralization tank to react quickly, resulting in partial neutralization of the material in the tank. And excessive alkalinity, the color of the product turns yellow and gray after the subsequent centrifugal washing, separation and drying, which affects the quality of the final product

[0006] 3. In the late stage of neutralization in ammonia water, due to the existence of a large number of crystals, a large number of solid phase crystals wrap the liquid phase that has not been neutralized to the end point, making it difficult for the newly added ammonia water to diffuse into the liquid phase that has not yet been neutralized to the end point. , resulting in a false end point, resulting in a decrease in the yield of the final product

[0007] 4. In the late stage of neutralization in ammonia water, due to the existence of a large number of crystals, a large number of solid phase crystals wrap the liquid phase that has not been neutralized to the end point, resulting in higher solid phase salt content and increased water consumption for washing in the subsequent solid-liquid centrifugal separation process

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