Cobalt promoted fused iron catalyst for ammonia synthesis

The effect of cobalt on the properties of cobalt modified iron fused catalyst for ammonia synthesis has been investigated by scanning electron microscopy, Mossbauer spectroscopy, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRFS) and Anger electron spectroscopy (AES). Introduction of cobalt changed considerably the sample behavior during activation and ammonia synthesis. The most active sample contained approximately 5.5 wt.% Co. Activation energies for the Co/Fe catalyst and iron catalyst were similar. The surface segregation of cobalt and iron has been postulated. This hypothesis was confirmed by an AES study of the model iron catalyst and the cobalt modified fused iron catalyst. Cobalt caused restructurization of iron to the Fe(111) face. This effect increased nitrogen adsorption and decreased hydrogen and ammonia adsorption and hence increased the catalytic activity of the Co/Fe catalyst. (C) 2000 Elsevier Science Ltd. All rights reserved.