The reduction of nanocrystalline cobalt oxide samples (single-phase and supported on γ-Al 2 O 3 ) was studied using in situ X-ray diffraction (XRD) analysis. The atomic structures of single-phase and supported Co 3 O 4 samples were refined, and the occurrence of cationic vacancies was demonstrated. A set of methods (XRD, temperature-programmed reduction, and differential dissolution) was used to find that the reduction of supported and unsupported model cobalt oxide was considerably different. The single-phase sample was reduced in undiluted hydrogen to cobalt metal with a hexagonal closely packed structure. The reduction of the supported sample (unlike the single-phase sample) occurred through the formation of a crystalline CoO phase to the formation of cobalt metal with a face-centered cubic structure. Interaction of cobalt oxide with the γ-Al 2 O 3 support, which hinders the reduction to cobalt metal, was detected.
No takes yet. Share an insight, caveat, or question.
Bulavchenko et al. (2009) studied this question.