Why Is Iron Used As a Catalyst (ammonia)?
I’m assuming you are referring to the Haber-Bosch nitrogen fixation reaction. If this is the case, then a catalyst is needed to lower the activation energy of the reaction so that the reaction can proceed at a reasonable temperature and pressure. Although N fixation is carried out at elevated P and T, it is also entropically disfavored (4 moles of gas produce only 2 moles of ammonia gas – not entropically favored). A catalyst is needed to lower that reaction’s activation energy by lowering the energy of the transition state such that the reaction can proceed – by definition of a catalyst. The catalyst surface may facilitate the interaction of the reactant molecules toward reduction and oxidation during the reaction to make the ammonia product.
