Titanium Tetraisopropoxide Precursor Research Articles

Synthesis and some properties of hybrid gels of titanium oxide containing europium (III)

In this work, we report the synthesis and properties of TiO 2 and of an organic–inorganic hybrid of TiO 2 where the inorganic network was obtained by hydrolysis (sol–gel process) of the titanium tetraisopropoxide precursor. Both materials were prepared and dried in air. The organic oligomer was synthesized by esterification between ethylene glycol and dipicolinic acid, using Eu 3+ as probe. These materials were studied by luminescence and infrared spectroscopies, thermogravimetric analysis and X-ray diffraction. The results obtained for the hybrid material show the formation of two crystalline polymers. Eu 3+ has been used as structural probe due to its photophysical properties and also as emission center for luminescent materials and the luminescence data indicate that Eu 3+ occupies one kind of site that is isolated from water molecules and OH groups.

TiO 2/SiO 2 mixed oxide catalysts prepared by sol—gel techniques. Characterization by solid state CP/MAS spectroscopy

The influence of synthesis parameters on the structural properties of mixed oxides derived from silicon tetraethoxide and titanium tetra-isopropoxide precursors has been studied by 29Si NMR speectroscopy. A first set of gels, prepared by complete hydrolysis of the individual precursors and subsequent mixing of the hydrosols, is characterized by comparatively narrow lines for the Q 2, Q 3, and Q 4 silica sites. Both the chemical shift values and the time constants of 1H 29Si magnetization transfer are similar to those found in pure silica gels. This indicates that these oxides consist of domains of the individual components. A different appearance of the CP/MAS spectra is noted for the second set of gels, which is prepared by addition of the titanium alkoxide component at a stage where the silicon alkoxide hydrolysis has only proceeded to about 50%, on average. The spectra of these samples are characterized by broad lines for the three types of sites. Larger contributions observed for Q 2 and Q 3 sites in these samples are attributed to the presence of SiOTi bridges. The influence of preparation parameters such as hydrolysis pH, drying temperature, and pore ripening treatment by redispersion in base, is studied by monitoring the spectral and dynamic parameters derived from the CP/MAS spectra.