Haber-Bosch process

What it is

The Haber-Bosch process makes ammonia by combining nitrogen and hydrogen. Nitrogen comes from the air; hydrogen is a separate feedstock. BASF's first ammonia synthesis plant began operating at Oppau, north of Ludwigshafen, on 9 September 1913. It brought a laboratory reaction into industrial production and provided a route from atmospheric nitrogen to fertiliser.

How it works

The gases react over a catalyst at high pressure and temperature. The presentation speech for the 1931 Nobel Prize in Chemistry describes BASF's operating conditions as approximately 200 atmospheres and around 500 degrees Celsius. These are historical conditions, not a specification for every plant.

Fritz Haber developed the laboratory process in Karlsruhe. Carl Bosch led its industrialisation at BASF. His team replaced Haber's osmium and uranium catalysts with iron and additives, making the catalyst cheaper and more readily available. Hydrogen attacked ordinary steel under the reaction conditions. Bosch's double-walled apparatus separated the demands on the materials: the inner tube withstood the heat, while the cooler outer tube contained the pressure.

Why it stands out

The achievement combined chemistry, metallurgy and plant engineering. BASF's history dates its partnership with Haber to 1908 and identifies Oppau as the introduction of high-pressure catalysis to the chemical industry. Industrial ammonia synthesis reduced reliance on natural nitrate deposits such as Chile saltpetre for nitrogen fertiliser.

Haber was awarded the 1918 Nobel Prize in Chemistry for ammonia synthesis, receiving it in 1919. Bosch shared the 1931 chemistry prize with Friedrich Bergius for developing chemical high-pressure methods.

Where you meet it

Its main historical connection to everyday life is nitrogen fertiliser. Oppau's ammonia was initially processed into ammonium sulphate. BASF also describes ammonia as a starting material for downstream products such as urea for glues and diesel exhaust treatment. The same chemistry had a military application: ammonia supplied nitric acid production for munitions during the First World War.