Synthesis of double oxides TiO2-SiO2 with low titanium content by hydrolysis of tetrabutoxytitanium-tetraethoxysilane mixture in an atmosphere of water vapor and ammonia

A series of TiO2-SiO2 binary xerogels with the titanium content lower than 7 mol % were prepared by joint hydrolysis of tetrabutoxytitanium and tetraethoxysilane in a desiccator in the atmosphere of vapor over 5% aqueous NH3 solution under static conditions. The physicochemical properties of the material were examined by IR spectroscopy and by the kinetic method with hydrogen peroxide decomposition as model reaction. © 2013 Pleiades Publishing, Ltd

Synthesis of Cu(II)-containing TiO2-SiO2 binary xerogels by hydrolysis of a mixture of tetrabutoxytitanium, tetraethoxysilane, and copper(II) chloride in a water-ammonia atmosphere

A Cu(II)-containing binary xerogel TiO2-SiO2 was synthesized by joint hydrolysis of tetrabutoxytitanium, teraethoxysilane and copper(II) chloride dissolved in their mixture. The synthesis was performed in a vapor of 10% aqueous ammonia under static conditions. EPR spectroscopy was used to examine the state of Cu(II) in the xerogel matrix. Data on specific features of the behavior of saccharose within xerogel pores under heating were obtained. The catalytic activity of the xerogel was tested by the kinetic method on model reactions of hydrogen peroxide decomposition and oxidative dehydrogenation of trimethylhydroquinone. © 2013 Pleiades Publishing, Ltd

Oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in the presence of titanium dioxide hydrogel

Liquid-phase oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in the presence of titanium dioxide hydrogel was studied by a kinetic method. Associative interactions between the substrate, oxidant, and gel were detected by voltammetry and ESR and IR spectroscopy.Russian Foundation for Basic Researc

Acidic and Electrosurface Properties of Binary tio2–sio2 Xerogels Using Epr of Ph‐Sensitive Nitroxides

The binary xerogels TiO2–SiO2 are widely used as catalysts and their carriers in organic synthesis. Characterization and adjustment of the electrostatic properties of the surface and the local acidity inside the pores, are necessary for the further development of TiO2–SiO2 xerogels applica-tions. This research investigates acid–base equilibria in the pores, and the surface electrostatic potential (SEP) of binary TiO2–SiO2 xerogels, by the EPR of stable pH‐sensitive nitroxide radicals. These radicals are small enough to penetrate directly into the pores, and to be adsorbed onto the surface of the material under study. This makes it possible to obtain valuable information on the acidic and electrosurface properties of the studied system. The highest negative surface electrical charge asso-ciated with surface electrical potential (SEP) was equal to –196 ± 6 mV. It was induced by the surface of the sample with a 7% TiO2 content. Тhe local acidity inside the pores of this sample was found to be higher, by approximately 1.49 pH units, as compared to that in the external bulk solution. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: D.O.A., E.G.K., D.P.T. acknowledge the financial support from the Russian Foundation for Basic Research (RFBR) grant 18‐29‐12129mk, I.A.K. acknowledges support from the Ministry of Sci‐ ence and Education of the Russian Federation grant No. 14.W03.31.0034 for the nitroxide synthesis

Surface electrical potential of ZrO2-SiO2 binary xerogels by EPR pH-sensitive spin probes

In this paper, we performed a qualitative assessment of the surface electrical potential for individual and binary xerogels based on silica and zirconia which were synthesized by hydrolysis in aqua ammonia medium. The effect of surface charge on near surface local acidity of solid-phase compositions was studied. © 2019 Author(s).We acknowledge the financial support of the Program 211 of the Government of the Russian Federation № 02.A03.21.0006, RFBR grants 17-03-00641 and 18-29-12129mk, the State Task from the Ministry of the Education and Science of the Russian Federation № 4.9514.2017/8.9

Synthesis of SiO2-TiO2 binary composites with cellulose as the substrate

A procedure for the synthesis of the SiO2-TiO2 binary material was developed. The procedure includes the formation of the silica matrix by impregnating cellulose plates with tetraethoxysilane followed by hydrolysis of the organometallic compound and burning-out of the cellulose constituent; activation of silica with HF; and deposition of titanium dioxide on the surface of the silica matrix by impregnating it with a solution of tetrabutoxytitanium, which is hydrolyzed in water-ammonia atmosphere. The physicochemical properties of the obtained material were studied. © 2013 Pleiades Publishing, Ltd