A comparative study of V species in beta zeolite by photoluminescence, diffuse reflectance UV-Visible and V-51 NMR spectroscopies

In calcined and rehydrated VSiB zeolite prepared following a method describ ed earlier, three kinds of tetrahedral VV species can be clearly identified by photoluminescence spectroscopy even at low V content, in contrast to V- 51 NMR and diffuse reflectance UV-Visible spectroscopies which do not allow them to be distinguished. A comparative study by photoluminescence and V-5 1 NMR spectroscopies leads to the suggestion that there is a correlation be tween the vibrational energy of the V=O bond and the corresponding chemical shift of the V-51 NMR signal.