Plasma catalytic reaction in ammonia synthesis in the microwave discharge

Practically, ammonia is made in the Haber process, in which the synthesis i s carried out on promoted iron catalyst at higher pressures and temperature s. In the plasma process, NH radicals were formed in the nitrogen-hydrogen plasma and the NH radicals would be quenched by hydrogen molecules to form ammonia. When the catalyst was placed in the plasma, synergistic effects of plasmas and catalysts on the ammonia synthesis were observed. The species in the ECR plasma do not collid in the plasma and the ammonia formation rea ction would proceed only on the surface of the catalyst. Thus the reaction occurred in the ECR plasma apparatus was investigated from both the identif ications of species in the plasma and adsorbed species on the surface of st eel substrate placed in the plasma to clarify the reaction scheme of the am monia synthesis. A dissociative adsorption of excited nitrogen molecules an d molecular ions or a direct adsorption of NH radicals on the surface of th e catalyst would promote the formation reaction of ammonia.