Method one
Ammonium carbamate is synthesized using carbon dioxide and ammonia under high temperature and high pressure, and after decomposition, absorption, conversion, crystallization, separation and drying.
Method Two
The preparation method is that the purified ammonia and carbon dioxide are mixed into the synthesis tower with a molar ratio of 2.8 to 4.5, the pressure in the tower is 13.8-24.6 MPa, the temperature is 180-200° C., and the residence time of the reaction material is 25-40 minutes, and the excess is obtained. The urea solution of ammonia and ammonium carbamate is decompressed and reduced in temperature, and the urea liquid separated from ammonia and ammonium carbamate is evaporated to 99.5% or more, and then pelletized in a prilling tower to obtain a urea product.
Method three
The final product of protein metabolism in mammals in urea. In 1922, industrial production of urea with ammonia and carbon dioxide was realized in Germany. Ammonia reacts with carbon dioxide to form carbamate amines, which are then dehydrated to produce urea.
Industrial process
Production method: Industrial use of liquid ammonia and carbon dioxide as raw materials, direct synthesis of urea under high temperature and high pressure conditions, the chemical reaction is as follows:
2NH3+CO2→NH2COONH4→CO(NH2)2+H2O.