The importance of C 7 sites and surface roughness in the ammonia synthesis reaction over iron

Abstract

In this note the authors present data which further supports the contention that C/sub 7/ sites (Fe atoms with seven nearest neighbors) are those most active in iron ammonia synthesis catalysts. Previous work in their laboratory showed that the synthesis of ammonia from its elements is a very structure sensitive reaction. It was found that the relative order of activity for ammonia formation was Fe(111) > Fe(100) > Fe(110). High pressure kinetic results presented here of ammonia synthesis over Fe(210) and Fe(211) surfaces in addition to the Fe(111), Fe(100), and Fe(110) surfaces show that the presence of highly coordinated sites is more important than surface roughness for high catalytic activity. 11 references.