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Haber process

The Haber-Bosch process is an industrial process used to manufacture ammonia from nitrogen and hydrogen developed by two Germans during the early 1900's.

Fritz Haber(1868-1934) Carl Bosch (1874 -1940)

Chemical equation
N2(g) + 3H2(g) <==> 2NH3(g)
 

Uses
Ammonia is mainly used in the manufacture of nitric acid, HNO3, fertilisers, and in the production of explosives. Ammonia is also used as an industrial refrigerant.

The following equations show how the fertilisers ammonium nitrate and ammonium sulfate are made.

Ammonia + nitric acid ==> ammonium nitrate

NH3 + HNO3 ==> NH4NO3

Ammonia + sulfiric acid ==> ammonium sulfate

2NH3 + H2SO4 ==> (NH4)2SO4

History
Before this process was developed Europe and particularly Germany obtained much of its needs from large guano deposits (dung from birds and bats) from Chile which were shipped across the Atlantic. During the early 1900's fertilisers were in short supply as they were being used up to grow food as the population of the world expanded.

Nitrogen in the form of nitrates and nitrites is needed by plants to make protein. Plants cannot directly use atmospheric nitrogen as it is unreactive because of the strong triple bond.

During World War I the British navy blockaded the shipments of guano to Germany in the hope to deprive the Kaiser of much needed raw materials which were used to manufacture explosives and to grow crops.

The Haber-Bosch process was developed by the German chemist Fritz Haber and the chemical engineer Carl Bosch to manufacture ammonia directly from atmospheric nitrogen and hydrogen obtained from methane or naphtha. Haber started to work on the process in 1904 and by the end of World War I in 1918 Germany was producing 95,000 tonnes of ammonia via the Haber process.

Raw materials for the Haber process: N2 and H2
1. Nitrogen, N2 is obtained from air(79% nitrogen) by fractional distillation.

2. Hydrogen, H2 is obtained by reacting steam with methane or naphtha

    methane +  steam  ==>  hydrogen + carbon dioxide
    CH4(g)   +  2H2O(g)   ==>   4H2(g) +  CO2(g)  

Conditions of the Haber process:
1. High tempearture between 400-500°C to maintain a high reaction rate.

2. High pressure between 250-350 atmospheres

3. Catalyst of iron oxide, Fe3O4