Reaction Principles

In all commercial processes, urea is produced by reacting ammonia and carbon dioxide at elevated temperature and pressure according the Basaroff reactions:

2NH3(l)+CO2l()  NH2COONH4 DH= -117 kJ/mol	1
NH2COONH4  NH2CONH2+H2O s DH= +15.5 kJ/mol	2

In the first reaction, carbon dioxide and ammonia are converted to ammonium carbamate; the reaction is fast and exothermic. In the second reaction, which is slow and endothermic, ammonium carbamate dehydrates to produce urea and water. Since more heat is produced in the first reaction than consumed in the second, the overall reaction is exothermic.
Complete conversion of ammonia and carbon dioxide into urea and water is limited. An important differentiator between processes is the way these nonconverted materials are handled.

Processes

1. Once-through process.
2. Conventional Recycle Processes.
3. Stamicarbon traditional CO₂ Stripping Process.
4. Stamicarbon’s Urea 2000plus™ process.
5. Stamicarbon’s Partial-Recycle (UAN) process