Urea is in many ways the most convenient form NH2COONH4 ↔NH2CONH2 +H2O for fixed nitrogen. It has the highest nitrogen content available in solid fertilizer (46%). It is easy to produce as prills or granules and easily transported in bulk or bags with no explosive hazard. It leaves no salt residue after use on crops. It specific gravity 1.335, decomposes on boiling and in fairly soluble in water. The principle raw materials required for this purpose are NH3 and CO2. Two reactions are involves in manufacture in urea. First, ammonium carbamate is formed under pressure by reaction between CO2 and NH3. CO2 + 2NH3→NH2COONH4 ∆H=-37.4Kcal This highly exothermic reaction is followed by an endothermic decomposition of ammonium carbamate. NH2COONH4↔NH2CONH2 +H2O
Various processes are;
-Snampogetti ammonia stripping process.
-Stamicarbon CO2 Stripping process
-Once through urea process
-Mitsui toatsu total recycle urea process.