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Why does the Haber-Bosch process use elevated temperatures?

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Difference in molecular structure between ammonia/amines and quaternary ammonium ions — ammonia Ammonia and amines have a slightly flattened trigonal pyramidal shape with a lone pair of electrons above the nitrogen. In quaternary ammonium ions, this area is occupied by a fourth substituent.

The Haber-Bosch process uses elevated temperatures to increase the rate of the chemical reaction between nitrogen and hydrogen, ensuring that ammonia is produced in a convenient and practical timeframe.12

While lower temperatures would theoretically favor a higher yield of ammonia at equilibrium, the reaction would proceed too slowly to be economically viable without the application of heat. To balance these factors, the process utilizes an iron-based catalyst, which enables the reaction to occur at a lower temperature than would otherwise be necessary, while high pressures are employed to maximize the proportion of ammonia yielded. In commercial production, this results in operating temperatures ranging from 400° to 650° C (750° to 1200° F).1