MOLYBDENUM OXIDE STRUCTURE ON SILICA-SUPPORTED CATALYSTS STUDIED BY RAMAN SPECTROSCOPY AND EXTENDED X-RAY ABSORPTION FINE STRUCTURE SPECTROSCOPY.

Raman spectroscopy and EXAFS (extended X-ray absorption fine structure) spectroscopy have been used to investigated the formation of molybdenum oxide on silica-supported catalysts. The existence and the structure of interaction species at low loadings are elucidated by both spectroscopies. The Raman data of the catalyst at higher loadings confirm the previously reported observations, that is, the presence of MoO//3 phase after the calcination at 773 K, while EXAFS spectra clearly demonstrate that the major molybdenum species is different from MoO//3 crystallite. The reason for the apparent contradiction is discussed.