Chlorine as a poison of the fused iron catalyst for ammonia synthesis

The poisoning effect of chlorine on the fused iron catalyst used for ammonia synthesis was studied. Chlorine adsorbs on the catalyst surface, reacting with potassium contained in the catalyst as well as with iron. The chlorine adsorption ability of the passivated catalyst is lower. The poisoning effect of chlorine on the activity of the iron catalyst is very strong and it is connected with the increase in the apparent activation energy of the ammonia synthesis process. Partial regeneration of the catalyst is possible by overheating at 920 K. The decrease of the amount of chlorine after overheating is only 12%. It suggests that chlorine is bonded not only as chlorides, but also as less volatile, oxygen-chlorine compounds.