Preparation and characterization of porous (Si$$_{1-x}$$Ti$$_{{x}}$$)$$\hbox {O}_{\mathrm {{2}}}$$ (x $$\le $$ 0.25) prepared by sol–gel hydrothermal process

An experimental strategy was developed to obtain ( $$\hbox {Si}_{1-x}\hbox {Ti}_{x})\hbox {O}_{\mathrm {2}}$$ ( $$x \le 0.25$$ ) porous materials via the sol–gel hydrothermal process. The sol was prepared from Si(OEt) $$_{\mathrm {4}}$$ (TEOS), Ti(OBu) $$_{\mathrm {4}}$$ (OBu: $$\hbox {OCH}_{\mathrm {2}}\hbox {CH}_{\mathrm {2}}\hbox {CH}_{\mathrm {2}}\hbox {CH}_{\mathrm {3}})$$ , 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 $$\hbox {N}_{\mathrm {2}}$$ 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.