Body-Centered Cubic Iron as a Catalyst

In the Haber-Bosch process, ammonia is formed from the reaction between N2 and H2, using a Fe304 (magnetite) catalyst promoted with A1203, CaO, K20 and a moderately small amount of iron and other elements [25], In this mixture, the catalytically active 

Another important factor in the catalytic properties of Fe and other metallic catalysts is the structure of these catalysts. It is a well-known fact that during ammonia synthesis, when it is exposed on the surface of a Fe catalyst s (111) plane, the catalyst is more active [14], 

In general, during the preparation of metallic catalysts, more than one type of crystallographic planes are uncovered, each of which exposes a characteristic pattern of atoms, for example, the crystallographic planes (111), (110), (100), and (010) [27], 

Besides, the geometric factor is important in the catalytic activity of iron, that is, the catalyst surface has irregularities such as steps and kinks that expose atoms with low coordination numbers which appears to be particularly reactive [22], 

FIGURE2.3 Chemisorbed nitrogen on an iron atom surface. 

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