Preparing process for biurea

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] ...