How is urea manufactured from ammonia and CO2?

Urea is produced by reacting ammonia with carbon dioxide in two steps: (1) Carbamate formation: 2NH3 + CO2 = NH2COONH4 (fast, exothermic). (2) Dehydration: NH2COONH4 = NH2CONH2 + H2O (slow, endothermic, equilibrium limited). Conditions: 180-210C, 150-250 bar. Overall conversion about 60-70%; unreacted ammonia and CO2 are recovered and recycled. Modern plants use stripping technology for efficient recovery. Final steps: concentration by evaporation, prilling or granulation for solid product. Urea is the most important nitrogen fertilizer (46% N content). Also used in: urea-formaldehyde resins, melamine production, AdBlue/DEF for diesel emission control. Production integrated with ammonia plant for CO2 supply.