No abstract

BACKGROUND: Preparation of homogeneous oxide coatings on the surface of fiberglass is a difficult task due to hydrophobicity of the fiberglass support. NiO-TiO 2 cannot coat the fiberglass surface homogeneously. In the present study, SiO 2 was added in the NiO-TiO 2 . A sol-gel method was used to prepare Ni-Si-Ti sol and this was used to coat fiberglass and form a complex Ni-Si-Ti oxide system supported on its surface. The catalyst was tested for hydrocarbon oxidation reaction. RESULTS: The as-prepared material is a mixture of TiO 2 in the anatase modification and SiO 2 in the amorphous phase. UV-visible diffusion reflectance spectroscopy confirmed the presence of Ni 2+Oh cations in the film bulk. Introduction of silica to the sample ensured a uniform distribution of the Ni-Ti oxide system on the fiberglass surface and its durable retention there at 600 ∘ C. The Ni-Si-Ti mixed oxide supported on fiberglass demonstrated a higher catalytic activity in the oxidation of n-heptane, compared to Ni-Ti oxide/fiberglass catalyst. It is stable even at 600 ∘ C, the temperature at which the maximum n-heptane conversion of 93% was reached. CONCLUSION: Adding SiO 2 in NiO-TiO 2 can coat fiberglass homogeneously as SiO 2 can coat hydrophobic surfaces such as fiberglass. This research provides a method with which to coat metal oxide catalyst on fiberglass that is very active and stable for oxidation of hydrocarbons even at high temparatures, compared to that without adding SiO 2 .

The paper presents the study of physicochemical processes occurring during the preparation of film-forming solutions, as well as the effect of the component composition on the stability of film-forming solutions over time. Compositions of stable film-forming solutions of TBT, TBT-TEOS, TBT-TEOS-AgNO3 suitable for the formation of thin-film coatings have been developed, and the time periods of stability of rheological properties have been determined. It was found that the addition of tetrabutoxytitanium after the establishment of chemical equilibrium in the solution increases the stability of the film-forming solutions. Optimization of the method of solutions preparation for obtaining films with reproducible physicochemical properties has been carried out.

No abstract

Two samples of TiO2 /Cr2O3 composites were synthesized as spherical grains by stepwise thermal treatment of ion-exchange resins, which were preliminarily saturated with chromium cations Cr3+ and dichromate anions Cr2O7 2– and covered with a film-forming solution of titania. The modes of calcination were based on thermal analysis and determined by the type of ion-exchange resin chosen as a template. The obtained composites consist mostly of the α-Cr2O3 phase, while the content of the TiO2 phase does not exceed 4 %. The composites retain the spherical grain shape of the initial ion-exchange resins with the size from 370 to 660 μm. Grains of the sample based on cationite, which adsorbs Cr3+ ions, have a pore structure with swells and voids. Grains of the sample based on anionite have fractures and cracks over the entire surface due to nonuniform distribution of adsorbed Cr2O72– anions in the initial anionite. The composites exhibit the catalytic activity in the complete oxidation of p-xylene. The sample based on cationite is more active. This may be related to a smaller accessible specific surface area of titania in the anionite-based sample due to formation of the Ti3+ solid solution in α-Cr2O3.