Synthesis and properties of spherical catalysts TiO2-SiO2/МхOy (M = Co and Cr)

Layered spherical materials were obtained, the inner layer of which is represented by oxides of cobalt or chromium, and external oxides of titanium and silicon. D-metals were fixed on the surface of the polymer substrate through sorption from aqueous solutions of the corresponding salts. The outer layer of the oxide titanium-silicon matrix was obtained by the sol-gel method. Aggregative stability of sols was controlled by viscosimetry. The influence of the components on the stability of sol solutions has been established. The time interval for the stability of sols is in the range of 400-1000 h. The laminated structure, material characteristics are studied using 3D-microtomography. The catalytic activity of the obtained TiO2-SiO2/Cr2O3 and TiO2-SiO2/Co3O4 samples was compared to the n-heptane oxidation reaction. The maximum heptane conversion for the TiO2-SiO2/Co3O4 sample is 80 % at a temperature of 600 °C, for the TiO2-SiO2/Cr2O3 sample, the conversion of n-heptane reaches 100 % at 400 °C

Synthesis of “Silica – Carbon Nanotubes” Composite and Investigation of its Properties

A new method for synthesis of CNT-SiO2 composite was developed. Oligomethylhydridesiloxane (OMHS) was used as the SiO2 precursor. The presence of active hydrogen in the composition of OMHS made it possible to obtain chemical interaction between the surface of carbon nanotubes and the deposited silica layer. The effect of the silica film on the CNT oxidizing ability was studied. It was found that the oxidation rate of the CNT-SiO2 composite decreases approximately by an order of magnitude in comparison with as-prepared CNT. The morphology and structure of amorphous silica obtained after oxidation of the CNT-SiO2 composite were studied. The thermal stability of the CNT-SiO2 composite was also studied. The CNT-SiO2 composite was found to be thermally stable up to temperatures of 1100-1200 ºC. An increase in the calcination temperature to 1300 ºC leads to segregation of the CNT-SiO2 composite into individual components: CNT and SiO2 particles

Synthesis and characterization of mesoporous silica thin films as a catalyst support on a titanium substrate

Mesoporous silica films with a thickness of 500–900 nm were synthesized on a titanium substrate by the evaporation-induced self-assembly method (with 900–1200 rpm for 90 s) using cetyltrimethylammonium bromide (CTAB) as structure-directing agent and tetraethyl orthosilicate as the silica source. Prior to coating deposition, the titanium substrate was oxidized to increase the surface roughness up to 500 nm and to produce a thin titania layer. Just before the synthesis, the titania layer was made super hydrophilic by an UV treatment for 2 h to provide a better adhesion of the silica film to the substrate. Films with hexagonal and cubic mesostructures with a uniform pore size of 2.8 nm and a surface area of 1080 m2/g were obtained and characterized by different methods. An alternative approach for surfactant removal by gradual heating up to 250 °C in vacuum was applied. Complete removal of CTAB from the as-synthesized silica films was confirmed by infrared spectroscopy