Iron as a Catalyst

Metallic iron can, in certain circumstances, act as a catalyst, in this respect resembling, albeit feebly, the more noble elements of Group VIII. of the Periodic Table. Thus, for example, iron assists the production of ammonia from a mixture of nitrogen and hydrogen at 800° to 1000° C. under a pressure of 100 atmospheres. No ammonia is obtained under these conditions in a porcelain vessel if iron or any other catalyst be excluded.

When reduced iron is heated with certain nitrogenous organic substances and metallic sodium, a cyanide is formed, the iron apparently acting as catalyser, being alternately oxidised and reduced. The presence of potassium cyanide in blast furnaces is thus readily accounted for.

Metallic iron sometimes behaves as a negative catalyst. Thus, for example, the activity of palladium as a hydrogen carrier is reduced by contact with iron, whereas cobalt and nickel exert no such influence.