Catalytic effect of iron wires on the syntheses of ammonia and hydrazine in a radio-frequency discharge

The catalytic effect of iron wires on plasma syntheses of ammonia and hydrazine has been studied in the nitrogen-hydrogen plasma prepared using rf discharge at a pressure of 650 Pa (5 Torr). The product was mainly ammonia including a small amount of hydrazine. When iron wires were placed in the plasma downstream of the gas flow, the yields of both products increased, about two times in ammonia and two orders of magnitude in hydrazine. The yields increased with increasing number of wires (the surface area of the catalyst). The dissociative adsorption of nitrogen molecules and/or molecular ions on the iron surface and the formation of NH_x by the reaction with hydrogen in the plasma followed by the formation of NH₃ or N₂H₄ are considered as a reaction scheme. This is supported by the identification of NH₃ with XPS of the surface of iron wires.Partly presented at the 10th International Symposium on Plasma Chemistry, August 4–9, 1991, Bochum, Germany.