The Haber-Bosch Process Revisited: On the Real Structure and Stability of 'Ammonia Iron' under Working Conditions...

摘要

The high pressure conversion of nitrogen in the presence of hydrogen and an appropriate catalyst, to form ammonia (Haber-Bosch Process) was developed 100 years ago and has undergone little change save for the introduction of a highly active iron catalyst as a replacement of highly toxic osmium. This improved catalyst is formed by the fusion of magnetite (Fe3O4) with irreducible oxides (K2O, Al2O3, CaO) in an oxide melt followed by mechanical granulation and careful reduction in the syngas feed. This technique gives rise to generation of crucial properties of the resulting α-Fe phase, which is commonly termed "ammonia iron." Model studies conducted with well-defined, simplified materials with clean surfaces at low pressures have contributed to the current knowledge of ammonia synthesis.