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Continuous clean preparation process and device of 2-hydroxy-4-methylthiobutyronitrile

A technology for methylthiobutyronitrile and a preparation process, which is applied in the chemical field, can solve the problems of polluted products, strong alkalinity of catalysts, polymerization or decomposition of raw materials and products, and achieves the advantages of improving production efficiency, mild catalytic reaction, and improving reaction rate. Effect

Pending Publication Date: 2019-04-19
LUFENG TIANBAO PHOSPHORUS CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] (1) The catalyst is highly alkaline, causing the polymerization or decomposition of raw materials and products;
[0009] (2) The catalyst is difficult to remove from the product and pollutes the product;
[0010] (3) The catalyst cannot be reused

Method used

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  • Continuous clean preparation process and device of 2-hydroxy-4-methylthiobutyronitrile

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Embodiment 1 Preparation of buffered heterogeneous catalyst

[0041] Take 3.5Kg H-type carboxylic acid-based domestically produced D113 macroporous ion exchange resin (if it is Na-type resin, it needs to be soaked in dilute acid solution to convert to hydrogen-type), rinse with a small amount of water to remove possible soluble impurities, add 2 Double the volume of industrial desalted water and swell for 30~60min. After swelling, remove floating mechanical impurities or broken resin, pour out excess water until the resin is just wet, and adjust to pH=4 with 2~10% sodium hydroxide or potassium hydroxide solution ~7 and keep it for 10~40min, then transfer the prepared catalyst directly into the packed tower or keep it moist and sealed for later use.

[0042] Other types of resins, such as sulfonic acid group and phosphoric acid group ionizing resin, prepare the catalyst steps as above.

Embodiment 2

[0043] Embodiment 2 raw material pretreatment

[0044] The crude HCN gas from the hydrogen cyanide synthesis workshop is subjected to two-stage absorption and deamination with 10-98% sulfuric acid to obtain the crude hydrogen cyanide gas composition as follows: HCN gas 9.4%±2%, hydrogen 1.6%±1%, nitrogen 79.4%±2%, oxygen 1.7%±1%, carbon monoxide 5.8%±2%, carbon dioxide 1.5%±1%, methane 0.6%±0.5%, water vapor 3.7%±2%;

[0045] The 3-methylthiopropanal raw material from the 3-methylthiopropanal (MMP) synthesis unit is mixed with 5-8% water by mass in a static mixer to obtain a water-dispersed emulsion.

Embodiment 3

[0046] Example 3 The first batch of synthetic reactions for the continuous production of 2-hydroxyl-4-methylthiobutyronitrile

[0047] Turn on the heat exchanger of the packed tower, and control the temperature inside the tower at 25-80° C. The tower is loaded with the carboxylic acid-based polymer resin buffer salt catalyst prepared in Example 1.

[0048] The thick HCN gas from the deammonization method of Example 2 enters from the bottom of the packed tower at a gas velocity of 2 to 15 L / min; the mixed emulsion of 3-methylthiopropionaldehyde and water mixed by a static mixer enters from the top of the packed tower , the flow rate is 1~10L / min, the two react countercurrently in the packed tower, and the crude cyanohydrin containing 1~8% MMP is obtained at the bottom of the packed tower, and the crude cyanohydrin is pumped to the top circulation port by the circulating pump at the bottom of the packed tower , Carry out the whole tower circulation to continue the reaction until...

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Abstract

The invention discloses a continuous clean preparation process and device of 2-hydroxy-4-methylthiobutyronitrile. A mild and stable buffered heterogeneous catalyst is loaded by using a packed tower, 3-methylthiopropanal is mixed with water and then is subjected to reverse-flow absorbing reaction with deamination HCN gas in the packed tower, a part of cyanohydrin obtained after reaction is extracted from the bottom of the packed tower through an extraction channel, another part of cyanohydrin is circulated into a material port in the tower and continuously react with substance flow in the towerto prepare cyanohydrin. The stable high-molecular catalyst is adopted to synthesize the cyanohydrin, impurities are not introduced in the reaction process, the catalyst is easily separated from a product and can be recycled, and the method is clean and saves energy. The buffered heterogeneous catalyst is milder than a traditional alkaline catalyst, can effectively reduce the occurrence of side reactions and product decomposition, the approximately colorless cyanohydrin product with the purity of 99.5% or above is obtained, continuous synthesis is easy to achieve, and the production efficiencyis improved.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a continuous cleaning preparation process and device for 2-hydroxy-4-methylthiobutyronitrile. Background technique [0002] 2-Hydroxy-4-methylthiobutyronitrile (cyanohydrin for short) is an important intermediate in the industrial production of methionine, from which D,L-methionine (MET) and D,L-hydroxymethionine analogs (MHB ). Both MET and MHB are methionine supplements that are widely used in the market. In 2016, the total global demand has exceeded 1.2 million tons, and the market capacity is still increasing year by year. [0003] 2-Hydroxy-4-methylthiobutyronitrile is generally synthesized by addition of 3-methylthiopropanal (MMP) and HCN under the action of a catalyst. The conventional catalysts used are weakly basic organic bases, such as triisopropanolamine, triethylamine, imidazole, and pyridine. Although this type of catalyst has a good effect of accelerating the re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C319/20C07C323/60
CPCC07C319/20C07C323/60Y02P20/10
Inventor 周荣超廖常福粟宇
Owner LUFENG TIANBAO PHOSPHORUS CHEM CO LTD