Abstract

An experimental strategy was developed to obtain Si-Ti-Ni transparent sols via the sol-gel process. The sol was prepared from Si(OEt)₄, Ti(OBu)₄ and Nickel(II) acetylacetonate. The chelating agent (2,4 pentanedione, acacH) was employed to stabilize Ti precursor in order to control their chemical reactivity, avoiding precipitation. A prehydrolyzed tetraethyl orthosilicate (TEOS) sol was the Si source. The sol was characterized by UV-Vis and Fourier Transform Infrared Spectroscopy (FTIR) spectroscopies. The solids treated were characterized by FTIR. Assignments of the simultaneous formation of the Si-O-Ti and Si-O-Ni bonds were done. The sol was polymerized at room temperature (293 K) to obtain gels and these were dried and treated at 673, 773 and 873 K in air. The characterization techniques were, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), 29Si Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR). The surface area of the solids was determined by N₂ adsorption/desorption isotherms. The corresponding average pore diameter was evaluated using the methods BJH, DA and HK. These models were used because all together cover the full range of the pore size. The purpose of producing porous polymeric system of SiO₂-TiO₂-NiO is to combine the properties of each of the oxides in a single material for use in catalytic reactions.

Keywords: Sol-Gel; SiO₂-TiO₂-NiO; Porous materials; Characterization techniques