Ammóniaszintézis

Ammóniaszintézis is the industrial process for producing ammonia. The most common method is the Haber-Bosch process, which involves the direct combination of nitrogen and hydrogen gases. Nitrogen is typically sourced from the air, which is about 78% nitrogen. Hydrogen is commonly obtained from natural gas through steam reforming, although other sources like coal gasification and electrolysis of water can also be used.

The synthesis reaction is exothermic and reversible: N₂(g) + 3H₂(g) ⇌ 2NH₃(g). To maximize ammonia yield, high pressures (typically 150-350 atmospheres) and moderately high temperatures (around 400-500 °C) are employed. A catalyst, usually based on iron, is essential to speed up the reaction rate, as the uncatalyzed reaction is very slow. The catalyst promotes the breaking of the strong triple bond in the nitrogen molecule.

The process involves several stages. First, hydrogen is produced and purified. Then, nitrogen and hydrogen are mixed in the correct stoichiometric ratio and compressed. This mixture is passed through a reactor containing the catalyst, where ammonia is formed. The resulting gas stream, which contains ammonia, unreacted nitrogen, and hydrogen, is cooled. Ammonia liquefies at these temperatures and pressures, allowing it to be separated from the remaining gases. The unreacted nitrogen and hydrogen are recycled back into the reactor. The produced ammonia is a vital component in the manufacture of fertilizers, explosives, and numerous chemicals.