Preparation process of azodicarbonamide

Abstract

The invention discloses a preparation process of azodicarbonamide. The process comprises the steps: 1) synthesizing a hydrazine hydrate crude product by a urea method; 2) refining hydrazine hydrate by a freeze separation method; 3) preparing biurea by alkaline condensation; and 4) obtaining the azodicarbonamide by a hydrogen peroxide oxidation method. According to the preparation process, different procedure production methods are analyzed and compared, the hydrazine hydrate is synthesized by selecting the urea method; refined hydrazine is obtained from crude hydrazine by the freeze separation method, biurea is prepared in a continuous condensation manner by an alkaline process, and finally, the azodicarbonamide is generated by the biurea oxidized by the hydrogen peroxide. Thus, the traditional acid condensation is changed into alkaline condensation to synthesize the biurea, consumption of raw materials and environmental pollution are reduced, hydrogen peroxide is selected as an oxidant in the oxidation process of the biurea, just by-product water is generated in the reaction, the environment is not polluted, and a green chemical pathway is taken.

Description

technical field [0001] The invention relates to a preparation process of azodicarbonamide. Background technique [0002] The production process of azodicarbonamide is divided into four parts: synthesis of hydrazine hydrate, refining of crude hydrazine, condensation reaction and oxidation of biurea. Most manufacturers use chlorine-based oxidants when they use urea to prepare hydrazine raw materials, and chlorine is also used as an oxidant when biurea is used to prepare ADC. Unreacted chlorine is discharged into the atmosphere, polluting the environment. As the country and society pay more and more attention to environmental protection, the pressure and restrictions on the use of chlorine will increase. For this reason, existing processes should be improved, such as using ketazine as a raw material and hydrogen peroxide instead of chlorine. oxidizing agent, etc. [0003] 1. At present, there are five main production processes for hydrazine hydrate at home and abroad: tradit...

AI Technical Summary

Problems solved by technology

[0011] (5) Air Oxidation Air Oxidation is currently the most advanced method of hydrazine production, the basic raw materials are only ammonia and air, other raw materials such as diphenylmethane Ketones, cuprous chloride, etc. can be recycled in the synthesis process, and are all readily available chemicals, but this method is difficult to achieve industrial production

[0012] 2. Crude hydrazine refining process

The hydrochloric acid contains a large amount of inorganic salts and organic amines and azo substances, which is difficult to handle

This process is low in cost and is adopted by most manufacturers in the world, but waste acid is generated and unreacted chlorine gas escapes, polluting the environment

In my country, chlorine gas is often used in the preparation of foaming agent ADC by oxidized biurea, which produces a large amount of hydrochloric acid by-products, causing serious pollution to the environment and wasting resources.

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