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Preparing process for biurea

A technology of biurea and seed crystals, which is applied in the field of preparing biurea, can solve the problems of acid mist at the operation site, high processing costs, and raw material loss, and achieve the goal of eliminating acid mist, high solid purity, and zero discharge Effect

Inactive Publication Date: 2007-06-27
JUHUA GROUP TECH CENT +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The above-mentioned preparation method has the following problems: 1. The yield of biurea to hydrazine hydrate is not high, generally 80-85%, 2. The condensation time is as long as 8-12 hours, 3. There is a pot phenomenon, and the acid mist at the operation site is diffuse , operational safety, poor industrial hygiene and loss of raw materials, 4. By-products (NH 4 ) 2 SO 4 The waste liquid contains a large amount of NaCl and Na 2 SO 4 , the processing cost is so high that it is useless
Therefore, the above problems have always been a difficult problem that plagues production and processing.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Put 500ml of anhydrous hydrazine hydrate (containing hydrazine hydrate 88.63g / L, sodium content 6.2mg / L, chlorine content 23mg / L) and urea 153g (hydrazine urea ratio is 1:3.45) in a heating, electric stirring, thermometer In a 1000 ml four-neck flask with a reflux device, stir at room temperature to completely dissolve urea, add sulfuric acid dropwise, adjust the pH value to 6, heat the reactant, control the reaction temperature at 100°C-120°C by heating to reflux, add catalyst C Acid 2.2 grams, add sulfuric acid dropwise under stirring, control pH to 5, add 0.1 gram of crystal seed, constantly adjust sulfuric acid dripping amount and dropping speed, be used to keep solution pH value and reaction temperature, react continuously for 6.5 hours to the end of reaction, (that is, the hydrazine content in the solution<0.1g / L) the product is filtered, washed and dried.

[0029] 103.5 g of biurea with a purity of 98.3% and a melting point of 252.8° C. to 254.2° C. was obtained,...

Embodiment 2

[0031] Put 600ml of anhydrous hydrazine hydrate (containing hydrazine hydrate 123.1g / L, sodium content 7.6mg / L, chlorine content 36mg / L) and urea 254.6g (hydrazine-to-urea ratio is 1:3.75) in a heating, electric stirring, thermometer In a 2000 ml four-necked flask with a reflux device, stir at room temperature to completely dissolve the urea, add sulfuric acid dropwise to adjust the pH to 6, heat the reactant, control the reaction temperature at 110-130°C by heating to reflux, and add 1.5 grams of catalyst oxalic acid , add sulfuric acid dropwise under stirring to control the pH to 5, add 0.15 grams of seed crystals, constantly adjust the amount of sulfuric acid added and the rate of addition, to keep the pH value of the solution and the reaction temperature, and continue to react for 6.2 hours to the end of the reaction (that is, the hydrazine in the solution content <0.1g / L) the product is filtered, washed and dried.

[0032] Obtain 142.4 grams of biurea with a purity of 97....

Embodiment 3

[0034] Put 500ml of anhydrous hydrazine hydrate (containing hydrazine hydrate 68.7 g / L, sodium content 10.2 mg / L, chlorine content 23 mg / L) and urea 118.7 g (hydrazine urea ratio is 1: 3.45) into the same flask as in Example 1 Stir at room temperature to dissolve it completely, add sulfuric acid dropwise to adjust the pH to 6, heat the reactant, control the reaction temperature at 90°C to 110°C by heating to reflux, add 3.3 grams of catalyst phosphoric acid, add sulfuric acid dropwise under stirring to control When the pH reaches 4, add 0.3 grams of seed crystals, and constantly adjust the amount of acid added and the rate of addition to maintain the pH value of the solution and the reaction temperature, and continue to react for 7.8 hours to the end of the reaction (that is, the content of hydrazine in the solution <0.1g / L). Filtered, washed and dried.

[0035] 78.9 g of biurea with a purity of 97.5% and a melting point of 251.7° C. to 254.5° C. were obtained, and the yield o...

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Abstract

The present invention is a kind of practical, economic and environment friendly biurea preparing process. Biurea is prepared with no-salt hydrazine hydrate and urea as main material and sulfuric acid as medium, and through adding catalyst, adding crystal seed and condensation reaction in heating and reflux conditions. The process has high biurea yield, high product purity, relatively low cost, short reaction period and other advantages.

Description

technical field [0001] The invention relates to a method for preparing biurea, in particular to a practical, economical and environment-friendly method for preparing biurea. Background technique [0002] Biurea, English name biarea chemical name is hydrazine dicarboxamide, molecular formula is C 2 h 6 N 4 o 2 .The chemical formula is H 2 NCOHNNHCONH 3 , an important intermediate of azodicarbonamide, a widely used chemical blowing agent, can also be used as a fire-resistant and anti-solvent for anti-skid high-grade cables for airstrips. [0003] In the prior art, biurea is produced by condensation of hydrazine hydrate and urea as raw materials in sulfuric acid and hydrochloric acid medium. The main reaction formula in its preparation process: [0004] 1. Condensation reaction [0005] NH 4 ·H 2 SO 4 +2NH 2 CONH 2 →H 2 NCOHNNHCONH 3 +(NH 4 ) 2 SO 4 [0006] 2. Neutralization reaction [0007] NH 4 ·H 2 O+H 2 SO 4 →N 2 h 4 ·H 2 SO 4 +H 2 o [0008]...

Claims

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Application Information

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IPC IPC(8): C07C281/06C07C273/18
Inventor 曹润生
Owner JUHUA GROUP TECH CENT
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