Making Ammonia - The Haber Process
The Haber process is used to manufacture ammonia, which can be used to make fertilisers and other chemicals.
Nitrogen from the air and hydrogen, which is usually obtained from natural gas, are purified and mixed in the correct proportions. The gases are passed over an iron catalyst at a temperature of about 450 degrees C and a pressure of about 200 atmospheres.
The reaction is reversible and so some ammonia breaks down into nitrogen and hydrogen. The gases are cooled so the ammonia condenses. The liquid ammonia is removed from the unreacted gases and they are recycled.
The yield is less than 20%, but the ammonia is produced quickly and no gases are wasted.