Characterization of Catalysts Based on Titanium Silicalite, TS-1, by Physicochemical Techniques

Desilication of TS-1 zeolite for the oxidation of bulky molecules

“…Desilicated zeolites exhibit a similar UV-vis spectra with two broad contributions at 200-210 nm and 250-290 nm. The larger contribution of the latter peak (caused by the desilication treatment) is in agreement with the formation of penta-, hexa-or octa-coordinated Ti species formed by interaction with water molecules [14][15][16][17][20][21][22]. The presence of these species clearly indicates changes in the coordination for sites located outside the micropores due to their less confined and more hydrophilic environment, in good agreement with the desilication process [22].…”

“…Catalytic activity of titanium-containing materials is related to the coordination of the Ti active sites and, more specifically, to the tetrahedrally coordinated Ti(IV) sites, which can be easily analyzed by UV-vis spectroscopy [16,[20][21][22]. The parent zeolite shows a band centered at 210-220 nm, which corresponds to isolated tetrahedrally coordinated Ti species, together with a broad shoulder between 250-290 nm associated with highly coordinated (oligomeric) Ti [6,[20][21][22]. The presence of extra-framework TiO 2 , usually observed at 330 nm and upwards, is negligible [22].…”

The study of Ti doped ZSM-5 particles and cavities inside them

“…[18] with diffuse reflectance spectroscopy (DRS) and Raman spectroscopy after a calcination procedure at 5501C. From the form of the Ti feature in the DRS spectra, the mean size of the anatase nanoparticles was estimated to be about 4 nm which is in good correlation with our results.…”

“…Also, the TEM micrographs of Ref. [18] cannot define their location because of the low resolution. In contrast to our study, the formation of cavities was not detected.…”

Microwave Fabrication of MFI Zeolite Crystals with a Fibrous Morphology and Their Applications

“…UV/Vis diffuse reflectance spectra, collected in vacuo after evacuation ( 10 À5 torr) at 627 K, revealed a strong peak around 210-240 nm, assignable to the ligand-to-metal charge-transfer absorption band from the oxygen to tetrahedral titanium(iv) atom in the zeolite framework. [14] The Ti-MFI-CH from the hydrothermal syntheses also showed practically the same XRD and IR data, indicating that the difference in the synthesis methods did not influence the identity of the final products.…”