Preparation and characterization of porous (Si1-xTix)O2 (x ≤ 0.25) prepared by sol-gel hydrothermal process

An experimental strategy was developed to obtain (Si1-xTix)O-2 {Si}_{1-x}\hbox {Ti}_{x})\hbox {O}_{\mathrm {2}}$$\end{document} (x <= 0.25 porous materials via the sol-gel hydrothermal process. The sol was prepared from Si(OEt)(4) (TEOS), Ti(OBu)(4) (OBu: OCH2CH2CH2CH3), anhydrous ethanol, deionized water and nitric acid. The reagents were mixed at room temperature (293 K) to obtain a homogeneous colourless liquid which was subjected to a hydrothermal process at 473 K using a stainless steel container. Finally, the material obtained was treated at 873 K in air. The surface area of the treated solids was determined by N-2 adsorption/desorption isotherms. The corresponding average pore diameter was evaluated using the Barret, Joiner and Halenda and Horvath-Kawazoe methods. Porous structures were obtained, in which the average pore diameter of the microporous ones was 1.4 nm. The characterization techniques employed were Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Raman spectroscopy, scanning electron microscopy, thermal gravimetric analysis, differential scanning calorimetry and UV-Vis diffuse reflectance spectroscopy. The Si-O-Ti bonds were detected by FTIR.