Continuous glycine synthesis method

Abstract

The invention relates to a continuous glycine synthesis method. The method comprises the following steps: preparing ammonia water; then mixing a chloroacetic acid solution with the ammonia water for asalifying reaction to obtain a solution A; dividing a mixed solution containing urotropin and ammonia water into a plurality of parts, separately adding the plurality of parts of the mixed solution into the solution A, carrying out an ammoniation reaction, and then performing cooling, crystallizing, and separating to obtain a mixed crystal of glycine and ammonium chloride and a mixed crystal mother liquor; taking the mixed crystal mother liquor as a solvent for preparing the ammonia water used in the step (1) or the chloroacetic acid solution used in the step (2); and continuing the reactionto realize continuous synthesis of glycine. According to the invention, a conventional one-step method is divided into three parts, i.e., ammonia dissolution, a salifying reaction and the ammoniationreaction, so a required amount of the ammonia water can be uniformly mixed with feed liquid, the problem of generation of many byproducts caused by local overheating due to ammonia absorption or a toohigh pH value of local feed liquid is avoided, the defects of conventional processes are effectively avoided, glycine yield is increased, and urotropine consumption is reduced.

Description

technical field [0001] The invention belongs to the technical field of glycine production, and in particular relates to a continuous glycine synthesis method. Background technique [0002] Such as figure 1 As shown, at present, the chloroacetic acid route adopts a batch method process, and the reactor adopts a batch stirring tank. After the catalyst hexamethamine is made into an aqueous solution, it is first added to the reactor, and then the chloroacetic acid solution and ammonia gas are respectively fed into the reactor at a certain flow rate. The ammonification reaction occurs in the kettle, and then a large amount of methanol is added to the feed liquid (synthesis liquid) for alcohol analysis, and then the crude product of glycine (containing glycine, a small amount of ammonium chloride and urotropine) and the mother liquor of glycine are obtained by centrifugation. The glycine crude product is washed, centrifuged and dried to obtain the glycine product; the glycine mot...

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Problems solved by technology

[0004] (1) High catalyst consumption

The catalyst urotropine is a one-time use, it will not be recycled after being added, and will eventually enter the waste water and products, which not only leads to excessive consumption, but also causes subsequent environmental protection problems

[0005] (2) Environmental issues

There are three aspects of environmental protection problems: ① "red water" is difficult to deal with

② It is difficult to deal with "yellow" ammonium chloride, because glycine, urotropine, reaction by-products and impurities are all in the ammonium chloride mother liquor, resulting in 60~70% ammonium chloride obtained by concentration can meet the product standard, and the remaining 30~40% of the ammonium chloride is yellow and sticky, the quality is not up to the product standard and needs to be reprocessed

③ Formaldehyde-containing wastewater treatment problems

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