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...

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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 iminodini...

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