Cobalt promoted fused iron catalyst for ammonia synthesis

The effect of cobalt on the properties of cobalt modified iron fused cataly st for ammonia synthesis has been investigated by scanning electron microsc opy, Mossbauer spectroscopy, X-ray diffraction (XRD), X-ray fluorescence sp ectroscopy (XRFS) and Anger electron spectroscopy (AES). Introduction of co balt changed considerably the sample behavior during activation and ammonia synthesis. The most active sample contained approximately 5.5 wt.% Co. Act ivation energies for the Co/Fe catalyst and iron catalyst were similar. The surface segregation of cobalt and iron has been postulated. This hypothesi s was confirmed by an AES study of the model iron catalyst and the cobalt m odified fused iron catalyst. Cobalt caused restructurization of iron to the Fe(111) face. This effect increased nitrogen adsorption and decreased hydr ogen and ammonia adsorption and hence increased the catalytic activity of t he Co/Fe catalyst. (C) 2000 Elsevier Science Ltd. All rights reserved.