Synthesis of dispersed silicon, titanium, and zirconium dioxides by pyrolysis of cellulose inorganic composites

The method of the synthesis of dispersed powders of silicon, titanium, and zirconium dioxides was developed, including formation of cellulose inorganic composites by impregnation of pressed granules of powdered cellulose with solutions of tetraethoxysilane and tetrabutoxy zirconium, hydrolysis of the organometallic constituent of the composite, pyrolysis of the cellulose matrix of the composite, and burning of its carbon constituent.     

Gel-synthesis, structure, and properties of sulfur-containing chitosan derivatives

The possibility of using the thermochemical approach to thermal decomposition of solids, previously developed by the author, to interpretation of the mechanism and kinetics of reduction of metal oxides with hydrogen was studied. Many properties of NiO reduction with hydrogen, including formation of metal nuclea, the nature of induction period, autocatalysis effect, equimolar and isobaric periods of reduction, the character of the effect of hydrogen pressure on reduction rate, and the nanocrystalline structure of a reduced metal, were explained in terms of the given approach.     

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.     

Silicon Dioxide Modified with Fluorine

IR spectroscopy and X-ray phase and chemical analyses were used to study the physicochemical properties of fluoride-containing amorphous silicon dioxide obtained by hydrolysis of (NH₄)₂SiF₆, and its previously unknown biocide properties were discovered. Results of biotesting are presented.     

Complexing Properties of Scandium(III) in Alkaline Medium

The behavior of scandium compounds in going from alkaline solutions to carbonate and hydrocarbonate solutions was studied. The possibility of coprecipitation of scandium(III) complex carbonate with zinc oxide was examined.     

Glycolate Ti1 − x Fe x (OCH2CH2O)2 − x/2 as a precursor for the preparation of quasi-one-dimensional (1D) solid solutions Ti1 − x Fe x O2 − 2x/2 (0 ≤ x ≤ 0.1)

Quasi-one-dimensional (1D) solid solutions Ti_{1 ? x} Fe _x (OCH₂CH₂O)_{2 ? x/2} (0 < x ≤ 0.1) with the structure of anatase were prepared by heating the glycolate Ti_{1 ? x} Fe _x (OCH₂CH₂O)_{2 ? x/2} in an atmosphere of air at a temperature of >450°C. The conditions of formation and the properties of the new glycolate Ti₃Fe₂(OCH₂CH₂O)₉ were described. It was found that the synthesized Ti_{1 ? x} Fe _x O_{2 ? 2x/2} solid solutions exhibit photocatalytic activity in the reaction of hydroquinone oxidation in an aqueous solution on irradiation with UV light. A correlation between the rate of oxidation of hydroquinone and the concentration of iron in the catalyst was established. A procedure for the preparation of titanium dioxide with the structure of anatase doped with iron and carbon (Ti_{1 ? x} Fe _x O_{(2 ? x/2) ? yCy)} and also composites on its basis, which contain an excess amount of carbon, was proposed.     

Titanium dioxide xerogel modified with powder cellulose in oxidation of trimethylhydroquinone

A procedure was developed for modification of titanium dioxide xerogel by addition of powder cellulose in the stage preceding hydrolysis of tetramethoxytitanium. The resulting catalytic systems based on the new material were studied in a model liquid-phase catalytic process of oxidative dehydrogenation of trimethylhydroquinone with atmospheric oxygen.     

Catalytic effect of nanosized metal oxides on the Hantzsch reaction

The effect of nanosized copper and aluminum oxides, which have a higher sorption capacity than that of bulk samples, on the Hantzsch reaction was studied. The adsorption of starting benzaldehydes and ethyl acetoacetate on the surface of copper and aluminum nanooxides resulted in the activation of these molecules and accelerated the Hantzsch reaction. In addition, considerable activation of ammonia and intermediates (chalcone and enamine) on the surface of aluminum nanooxide facilitated an increase in the rate and selectivity of the process. The experimental results were used to develop a one-pot method for the preparation of nifedipine and nitrendipine.     

Synthesis of ZrO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> and ZrO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript>–Cu(II) xerogels by joint hydrolysis in an aqueous ammonia atmosphere

ZrO₂–SiO₂ xerogels have been synthesized through hydrolysis of a mixture of tetrabutoxyzirconium and tetraethoxysilane in a desiccator in a vapor of a 15% aqueous NH₃ atmosphere. ZrO₂–SiO₂–Cu(II) xerogels were synthethized analogously through joint hydrolysis of a mixture of the organometallic precursors and copper(II) chloride. The effect of synthesis conditions on the physical and chemical properties of the resulting material has been studied.