Why does the Haber-Bosch process use an iron-based catalyst?

The Haber-Bosch process utilizes an iron-based catalyst primarily to enable the synthesis of ammonia from nitrogen and hydrogen at a lower temperature than would otherwise be practicable.1

While the chemical equilibrium between these elements favors the formation of ammonia at lower temperatures, the reaction rate at those temperatures is too slow for efficient production. By using a catalyst—typically iron containing iron oxide—the process can achieve a satisfactory rate of ammonia formation at elevated temperatures (400–650 °C) while maintaining economic feasibility. This catalyst functions by providing an active surface that facilitates the reaction without altering the final equilibrium position.1234