THE EFFECT OF COBALT ON THE ACTIVATION OF FUSED IRON CATALYST FOR AMMONIA-SYNTHESIS

BET, scanning electron microscopy, X-ray diffraction, Mossbauer spectr oscopy, X-ray fluorescence spectroscopy and McBain thermobalance were used to investigate the effect of cobalt on the reduction behaviour an d activity of fused iron catalyst for ammonia synthesis. Activity test s were carried out under 10 MPa in the 350-450 degrees C temperature r ange. Studies were performed on the traditional multipromoted iron cat alyst and on the series of catalysts prepared with addition of cobalt. Addition of cobalt promoted the iron catalyst for ammonia synthesis. The most active sample was that containing approx. 5.5% wt Co. Cobalt changed the reduction behaviour of the catalyst. The rate of the surfa ce change during reduction was higher for the case of the 'cobalt cata lyst'; however the rate of mass change was higher for a typical iron c atalyst. The process of reduction was probably followed by the formati on of an Fe3Co compound and by the surface faceting, with the exposure of an Fe(111) plane.