Production of Ammonia

Because of its many uses, ammonia is one of the most highly-produced inorganic chemicals. Before World War I most ammonia was obtained by the dry distillation of nitrogenous vegetable and animal products; by the reduction of nitrous acid and nitrites with nascent hydrogen; and also by the decomposition of ammonium salts by alkaline hydroxides or by unslaked lime (quicklime), the salt most generally used being the chloride (sal-ammoniac) thus

2NH₄Cl + 2CaO CaCl₂ + Ca(OH)₂ + 2NH₃

It was also obtained by decomposing magnesium nitride (Mg₃N₂) with water,

Mg₃N₂ + 6H₂O 3Mg(OH)₂ + 2NH₃

Today the Haber-Bosch synthesis is the most important method for production of ammonia. In this process, nitrogen and hydrogen gases combine directly on an iron catalyst at high pressure of 3000 lbf/in² (20 MPa) and temperature (500 °C) to produce ammonia.

N₂ + 3 H₂ 2 NH₃

Compared to older methods, the Haber process's feedstocks are relatively inexpensive—nitrogen makes up 78% of the atmosphere, while hydrogen can be readily produced from natural gas.