3724a.     WINTER, E.  [Catalytic Decomposition of Ammonia Over Iron.]  Ztschr. physik. Chem., vol. 13, Abt. B, 1931, pp. 401-424; Chem. Abs., vol. 26, 1932, p. 364.

          Catalytic decomposition of NH₃ in NH₃-H₂ or NH₃-H₂-N₂ mixtures was studied over Fe catalysts at 500°-700° by a flow system.  On supported Fe catalysts the rate of decomposition was approximately proportional to the partial pressure of NH₃ and inversely proportional to the 3/2 power of the partial pressure of H₂.  H₂ was without effect on the decomposition.  One series of runs over a roll of Fe gauze indicated that the rate of decomposition was proportional to the first power of NH₂ partial pressure and inversely to the first power of H₂.  The energy of activation over the temperature range studied is about 51,000-54,000 cal.  The relation between catalytic activity and formation of Fe nitride is discussed.  The results indicate that the reaction rate depends upon the concentration of atomic N on the surface of the catalyst.