COMPARATIVE-STUDY OF THE REDUCTION KINETICS OF MAGNETITES AND DERIVED AMMONIA-SYNTHESIS CATALYSTS

A study of the reduction behaviour of both natural and synthetic magnetite, as ammonia synthesis catalyst precursors, as well as of the synthesized catalysts, was performed by differential thermal analysis and thermogravimetric analysis in hydrogen under nonisothermal conditions. The presence of promoters in the synthesized catalysts caused shifting of the temperatures of the beginning and end of the reduction toward higher values relative to those of the starting magnetites. The close values of the activation energy of the reduction (E) indicated the existence of the same mechanism of reduction of the catalysts and the precursors. Wustite was not detected by the applied Mossbauer spectroscopic measurements.