EFFECT OF METALLIC COBALT PARTICLES SIZE ON OCCURRENCE OF CO DISPROPORTIONATION - ROLE OF FLUIDIZED METALLIC COBALT-CARBON SOLUTION IN CARBON NANOTUBE FORMATION

The behavior of Co-MgO catalysts in the reaction of CO disproportionat ion was studied in the temperature range up to 800 degrees C. Two temp erature regions that differ by the morphology of graphite produced ('' egg-shells'' or nanotubes) were detected. The experimental data obtain ed were analyzed in terms of the phase equilibria ''amorphous carbon'' - ''carbon solution in metallic Co'' and ''graphite'' - ''carbon solu tion in metallic Co''. Under certain assumptions, the Co degrees parti cles are considered to dissolve amorphous carbon under the reaction co nditions and transform to oversaturated fluidized carbon-cobalt soluti on, these fluidized particles being responsible for the formation of c arbon nanotubes.