Production process and production system of methionine and methionine hydroxyl analogue

Abstract

The invention belongs to the field of preparation of feed preparations, and particularly relates to a production process and a production system of methionine and methionine hydroxyl analogues. The process compriseeds the following steps: (1) carrying out rapid unsaturated ammoniation on cyanohydrin and ammonia water to prepare a 2-amino-4-methylthio butyronitrile crude reaction solution; (2) reacting the aminobutyronitrile crude reaction liquid with a solid catalyst to obtain methionine hydrolysate; (3) filtering, deaminizing, concentrating and separating the methionine hydrolysate to obtain methionine solid and crystallization mother liquor, the solid catalyst being a cerium oxide catalyst or a solid acid catalyst. According to the production process provided by the invention, an independent cyanohydrin rapid unsaturated ammoniation strategy is adopted, and interference of materials, catalysts and reaction products in other steps on the cyanohydrin ammoniation step is avoided as much as possible, so that adverse side reactions such as cyanohydrin decomposition and excessive ammoniation are avoided.

Description

technical field [0001] The invention belongs to the field of feed preparation preparation, and in particular relates to a production process and production system of methionine and methionine hydroxyl analogs. Background technique [0002] Methionine (2-amino-4-methylthiobutyric acid, MET) and methionine hydroxyl analogs (2-hydroxy-4-methylthiobutyric acid, MHA) have been widely used as animal feed additives to supplement the necessary methionine for animals. use. However, in the current technology, the two often need to be produced separately due to the difference in the post-process of the intermediate 3-methylthiopropanal or up to 2-hydroxy-4-methylthiobutyronitrile (cyanohydrin), and also consume a large amount of acid Alkali generates unnecessary low-value by-product salts, and it is difficult to completely separate the product from the inorganic salts. Chinese patent CN109467526A discloses a method for producing methionine and / or methionine hydroxy analogs by 3-methy...

AI Technical Summary

Problems solved by technology

[0003] But it still exists following main problem, at first, although this method improves the inclusiveness of cyanohydrin ammoniation process by setting MET, MHA as recovery target simultaneously, but because it starts from 3-methylthiopropanal in the same The preparation of MET and MHA by reaction in an environment is complicated and lacks controllability; especially in this method, it is obvious that cyanohydrin directly reacts with cerium oxide to be hydrolyzed into MHA, which is far more than the reaction between cyanohydrin and ammonia to form aminobutyronitrile and then contact with cerium oxide It is easy to hydrolyze into MET, so it is difficult to achieve a high MET content in the final product. Since MET recovery needs to be crystallized from the system, more MHA will seriously affect MET crystallization and further Affects its separation and recovery, especially when concentrated to increase its concentration in order to recover MET as much as possible, MHA will easily polymerize into dimers and oligomers with higher viscosity, making it more difficult to recover MET or appear coated with MHA. Sticky agglomeration; On the contrary, if MET is not taken out as much as possible, it is uneconomical to sell MHA with a higher value than MHA. In addition, higher MET content will affect the long-term uniformity, stability, and flow of high-concentration MHA. Sexuality, etc. affect its storage and use

Secondly, in addition to the main reaction, there are also many side reactions in the complicated process of the method. In addition to the cyanohydrin or the incompletely hydrolyzed amide intermediate of aminobutyronitrile listed in its examples, hydrogen cyanide and cerium dioxide are contacted at the beginning. Formic acid will also be generated. In the ammoniation process of cyanohydrin, aminobutyronitrile is further ammoniated into iminodinitrile and finally hydrolyzed into iminodiacid. These common side reaction impurities have not been overcome in this method, and in practice During the production, the mother liquor will be continuously enriched after repeated cycles and will have an adverse effect on the product

In addition, although the preferred embodiment of this patent is not reflected, those skilled in the art know and easily observe and monitor, unstable 3-methylthiobutyraldehyde and more and stronger base (directly in this invention) When contacting with the 28wt% ammonia water raw material that ammoniation is used), be to easily take place polymerization and decomposition reaction, this can cause the unfavorable dark color impurity of product and yield to reduce

[0004] In summary, the main problems in the existing technology are: the production of traditional MET and MHA often needs to consume a large amount of acid and alkali, and generate low value-added by-product salts, and it is difficult to completely separate the products from the by-product salts

The method that CN109467526A proposes to produce methionine and / or methionine hydroxy analogs by 3-methylthiopropanal has too many types of raw materials added at one time, multi-step reactions are carried out simultaneously, the controllability of the reaction process is poor, and the content of MET obtained is higher than that of MHA low, resulting in the difficulty of effective separation of the two, and the problem that there are many after-treatments required to obtain qualified products; in addition, there are unfavorable problems such as 3-methylthiopropionaldehyde and a large amount of high-concentration ammonia water, hydrogen cyanide and cerium dioxide. Simultaneous mixing of raw material combinations, as well as incompletely hydrolyzed amide intermediates and ammoniated by-product iminodinitriles without further treatment

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