New process for producing high-purity iminodiacetonitrile

Abstract

The invention relates to a new process for producing high-purity iminodiacetonitrile. The new process is characterized in that: high-purity reaction liquid is obtained by using a process for synthesizing iminodiacetonitrile at high conversion rate; and white or pale yellow high-purity iminodiacetonitrile with iminodiacetonitrile content of over 99 percent is produced by using a synthesis reactionliquid decolorizing process, an impurity removal process and three crystallization processes, wherein a part of thin waste liquid produced during the production is returned to a raw material preparation system, the rest part of waste liquid is conveyed to a biochemical device for processing, and the produced thick waste liquid is directly conveyed to an incinerator for processing, so that pollution-free production of the entire process is realized. The new process has the advantages of high product quality, white color, purity of over 99 percent high product yield, iminodiacetonitrile yield of about 90 percent during the entire production process and low three-waste treatment difficulty.

Description

technical field [0001] The invention relates to a process for producing high-purity iminodiacetonitrile. Background technique [0002] Iminodiacetonitrile (IDAN) is an important raw material for the production of glyphosate, and its development momentum has been strong in recent years. [0003] The production of iminodiacetonitrile is divided into raw material route, which is divided into hydrocyanic acid method and hydroxyacetonitrile method. [0004] U.S. patents disclose a large number of processes for producing iminodiacetonitrile by hydrocyanic acid method, such as: US2794044, US3167580, US3412137, US3886198, US3904668, US3988360, US4307037, etc. The disadvantages of the above process are: [0005] First, the raw material hydrocyanic acid is not easy to preserve, and it is easy to leak and cause danger during the production process; second, the conditions are harsh and the time required is long; third, the yield of iminodiacetonitrile is low and the economy is poor; f...

AI Technical Summary

Problems solved by technology

The traditional process adopts ordinary mixing, temperature control in one or two stages, and the residence time is longer, resulting in more polymers in the synthesis stage, which affects the product yield and product quality

[0011]Second, the traditional process has no reaction liquid purification process

Due to the problems in the reaction control link and the lack of reaction liquid purification process, the purity of the product after the second crystallization of iminodiacetonitrile is already very low, and the impurity content is also high, so it is impossible to carry out three-stage concentration and three-stage crystallization.

Therefore, the total yield of the product can generally only reach 78-80%, and a large amount of iminodiacetonitrile cannot be recovered, and it will be burned in the thick waste liquid

cause great waste

[0013] Fourth, the iminodiacetonitrile produced by the traditional process needs to be purified from raw materials before producing glyphosate, which brings adverse effects to downstream industries

However, at present, the content of industrial iminodiacetonitrile is mostly about 92%. After neutralization of the reaction solution, the content of the primary acid (IDA) obtained after solid-liquid separation of iminodiacetic acid (IDA) can only guarantee 97%, and the color is relatively dark. Poor, needs to be decolorized

Moreover, the mother liquor has high impurity content and cannot be applied mechanically (the product quality drops sharply after application), so the secondary acid and the tertiary acid can only be processed in stages to obtain the secondary acid (IDA, content 90%), the tertiary acid (IDA, content 70%), four or more acids (IDA, content below 50%), and two or more acids (accounting for 20% of IDA) must be refined to more than 97% before they can enter the synthesis of diglyphosate, the process is extremely cumbersome ; Repeated refining, the impurities in the mother liquor continue to accumulate, and the mother liquor is finally withdrawn. On the one hand, the final mother liquor contains iminodiacetic acid (about 20%), which causes a loss of yield after withdrawal, and on the other hand increases the treatment cost of the three wastes

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