Preparation and EXAFS characterization of alumina supported molybdenum nitrides

Nitrided Mo/Al2O3 catalysts were prepared by temperature-programmed reaction between NH3 and MoO3/Al2O3. XRD and EXAFS methods were used for the structural characterization. The results of XRD show that the molybdate in the supported samples exists as dispersed MoO3 and γ-Mo2N before and after nitriding, respectively. The small coordination numbers of Mo-N shells indicate that the γ-Mo2N in the supported samples possesses high dispersion, the lower loading of Mo, the higher dispersion of γ-Mo2N on alumina. From the view of coordination distance, it is found that with the increase of dispersion of γ-Mo2N, the Mo-N distance is a little shortened, which may have resulted from the nano-shortening phenomenon. γ-Mo2N phase in the supported samples has high dispersion