process for producing ammonia by reaction of nitrogen
3H2 ⇌ 2NH3.
It was developed in 1908 by Fritz Haber and was developed
for industrial use by Carl Bosch (1874 -1940), hence
the alternative name Haber-Bosch process.
The reaction is reversible
and exothermic, so that a high yield of ammonia is
favored by low temperature.
However, the rate of reaction
would be too slow for equilibrium to be reached at
normal temperatures, so an optimum temperature of
about 450°C is used, with a catalyst of iron containing
potassium and aluminum oxide promoters.
the pressure the greater the yield, although there
are technical difficulties in using very high pressures.
A pressure of about 250 atmospheres is commonly employed.
The process is of immense importance for the fixation
of nitrogen for fertilizers.