How is ammonia produced industrially?

Ammonia is produced by the Haber-Bosch process: N2 + 3H2 = 2NH3. Process steps: (1) Hydrogen production - steam reforming of natural gas (CH4 + H2O = CO + 3H2) followed by water-gas shift (CO + H2O = CO2 + H2). (2) Air separation for nitrogen. (3) Syngas purification - remove CO2 and CO. (4) Synthesis - over iron catalyst promoted with K2O and Al2O3, at 400-500C and 150-300 bar. Equilibrium favors products at low temperature and high pressure. Single-pass conversion is 15-25%; unreacted gas is recycled. Ammonia condensed from product stream. Major use: fertilizers (urea, ammonium nitrate, DAP). Also for explosives, plastics, and industrial chemicals. Large-scale plants produce 1000-3000 tons/day.