Skeletal Spectra of Precursors for Metal Oxide Catalysts

In many cases, the skeletal spectra of amorphous oxides are similar to those of the corresponding crystalline materials, with broader and less-resolved features. 

This is the case, for example, in amorphous versus crystalline V2O5 [72]. In a few cases, however, amorphous material may also have relatively unusual features, different from those of the crystalline counterparts. For example, amorphous alumina is characterized by only octahedral cation coordination, in contrast to transitional aluminas which also have tetrahedral A1 coordination. The skeletal IR spectrum of amorphous alumina is characterized by a strong band near 550cm , and by the absence of the feature in the region near 800 cm , associated with AIO4 tetrahedra, present in crystalline transitional aluminas [73]. 

Skeletal Spectra of Precursors for Metal Oxide Catalysts 

Oxide catalysts may be obtained by thermal decomposition of precipitated precursors. These materials, usually easily decomposable soUds, may be salts such as carbonates and nitrates, whose skeletal spectroscopic features have been discussed above. Alternatively they may be simple or complex hydroxides. 

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