Method for preparing iminodiacetic acid by using raw material of hydroxy acetonitrile

Abstract

This invention provides a 'one-pot' method for preparing and separating iminodiacetic acid from hydroxyl acetonitrile. The method has such advantages as high yield, little waste discharge, and easy preparation and purification of the product.

Description

technical field [0001] The invention relates to a method for preparing iminodiacetic acid and its salts by using hydroxyacetonitrile as a raw material, in particular to a method for synthesizing and separating iminodiacetic acid by using hydroxyacetonitrile as a raw material through one-step acidolysis. Background technique [0002] The domestic industrial production methods of iminodiacetic acid mainly include hydrogen cyanide method, chloroacetic acid method and diethanolamine method. The chloroacetic acid method is a mature process, but the process is long, the product purity is low, the cost is high, and the "three wastes" are serious, so it is already an obsolete process. Diethanolamine method is a new technology developed in foreign countries in the 1990s. This method uses diethanolamine as the main raw material, under the presence of high temperature (170°C), high pressure (0.8Mp) and Cu-Ni alloy catalyst and sodium hydroxide, oxidative dehydrogenation , to generate ...

AI Technical Summary

Problems solved by technology

This method has high requirements on equipment and catalysts, and there are potential safety hazards, and the raw material diethanolamine is affected by the price of crude oil, resulting in high production costs. At the same time, there are economic, technical and environmental factors such as three wastes and catalyst deactivation. The competitiveness of this process Not strong

[0003] The hydrocyanic acid method is generally favored at home and abroad. U.S. Patent No. 5,187,301 reports the preparation of iminodiacetonitrile by the batch method of hydroxyacetonitrile, followed by hydrolysis with sodium hydroxide, acidification, crystallization, separation, and the method for preparing iminodiacetic acid , has been widely favored or adopted by relevant manufacturers at present, but this method has poor reaction selectivity, serious decomposition and polymerization in the process, easy to produce tar, complex post-processing, too many times of solid-liquid separation, and a small amount of hydrocyanic acid when there is solid-liquid separation And the safety and environmental protection of ammonia escape, the waste water produced by aminoacetonitrile and iminodiacetonitrile is difficult to deal with, and must be treated with high-investment and high-energy-consuming incineration devices; low ammonia recovery rate, large investment, low ammonia concentration, and poor use value ; The yield of iminodiacetic acid p-hydroxyacetonitrile is only about 60%