EXAFS study of γ-Mo2N and Mo nitrides supported on zeolites
Materials Letters 54 (2002) 364-371，-0001，（）：
By analysis of the extended X-ray absorption fine structure (EXAFS) of the Mo K-absorption edge, the structural information of both oxidic and nitrided Mo catalysts supported on zeolites was obtained. The supported MoO3 samples show three peaks in the radial structure function (RSF). The first two peaks represent the nearest Mo-O coordination shell and the ratio of the first peak to the second one is much larger than that of the MoO3 crystallites, which suggests that the MoO3 supported on zeolites has a compact structure than the unsupported one. Three peaks on the RSF of g-Mo2N represent one Mo-N and two Mo-Mo coordination shells, respectively. This is in good agreement with the face-centered cubic model. Calculation from X-ray diffraction data and EXAFS spectra reveals that the N atoms in γ-Mo2N lengthen the distance between Mo atoms and weaken the Mo-Mo bond. Supported Mo2N samples give out nearly the same RSFs as the γ-Mo2N and only the peak corresponding to Mo-N shell is weak. This suggests the supported Mo2N has more configurational disorder.