How does the Haber-Bosch process use hydrogen and nitrogen to make ammonia?
The Haber-Bosch process is the primary industrial method for synthesizing ammonia by directly combining nitrogen from the air with hydrogen.12
The Chemical Reaction
The synthesis follows the chemical equation:
To make this reaction economically feasible, the process employs several critical conditions:
* High Pressure: The reaction is carried out at pressures typically ranging from 200 to 400 atmospheres (though ranges of 100–1,000 are possible) to increase the yield of ammonia.12
* Temperature: While lower temperatures favor ammonia formation, high temperatures (400°–650° C) are necessary to achieve a practical reaction rate.12
* Catalyst: An iron-based catalyst is used to enable the reaction to occur at these temperatures.12
Process Details
The hydrogen required is typically obtained by decomposing water or from fossil fuels. Because the reaction only converts a fraction of the gases per pass, the ammonia is removed as it forms, and the remaining nitrogen and hydrogen are recycled back into the system. Any oxygen-containing compounds must be carefully removed beforehand, as they act as poisons that reduce the effectiveness of the catalyst.314