Volume 66, Nº 6 (2025)

The work is devoted to revealing the influence of the synthesis method, namely the nature of the template, on the catalytic properties of the supported Ni/Ce_xSn_1–xO₂ systems in dry reforming of methane (DRM) in a flow system with a fixed catalyst bed. A comparison of the characteristics of catalysts obtained using different templates (ionic – cetyltrimethylammonium bromide (CTAB), non-ionic polymer Pluronic-123 (P123), biotemplate – pine sawdust) and containing cerium and tin in a molar ratio of Ce : Sn = 9:1 was carried out. The mass content of nickel was 3%. The catalysts were characterized by temperature-programmed reduction with hydrogen, X-ray diffraction, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy with energy-dispersive X-ray analysis, and magnetometry. The systems obtained in the presence of the biotemplate and P123 were active in CDRM. The highest values of steady-state conversion of methane (11%) and carbon dioxide (29%) were provided by the Ni/CeO₂–SnO₂–P123 catalyst. Analysis of the results of physicochemical methods showed that the Ni/CeO₂–SnO₂–P123 sample has the most uniform distribution and increased dispersion of nickel particles. It was found that the use of the P123 polymer template contributes to the formation of a greater number of interaction centers of nickel with the tin-containing oxide phase in the Ni/Ce_xSn_1–xO₂–P123. The nature of the template significantly affects the structural state of the active component and, as a consequence, the catalytic characteristics in DRM.

A series of iron-containing catalysts supported on γ-Al₂O₃ and modified with potassium and cobalt were studied in the reaction of hydrocarbon synthesis from CO₂. Samples from different series differed in the deposition method and component ratios. When preparing catalysts modified with cobalt and potassium by co-impregnation in excess of impregnation solution, an uneven distribution of cobalt and iron cations was observed on the catalyst surface. Applying iron and modifiers by consecutive impregnation in excess of impregnation solution with intermediate heat treatment in air allows for a uniform distribution of cobalt and iron cations. This leads to a significant increase in selectivity for C₅₊ hydrocarbons formation and a decrease in methane selectivity. For catalysts prepared by the consecutive impregnation method, the optimal cobalt-to-iron ratio was found to be n_Co/n_Fe ≈ 0.35–0.45, along with an iron active component content of ω_Fe ≈ 4%.

The photocatalytic activity of Cd_1–xZn_xS (x = 0–1) and TiO₂/Cd_1–xZn_xS composites in the reaction of hydrogen evolution under visible light irradiation (λ = 410 nm) was studied. In the system with an aqueous solution of C₂H₅OH used as a sacrificial agent, the maximum activity (1.6 mmol g^–1 h^–1) was demonstrated by Cd_0.1Zn_0.9S. When using 0.1 M Na₂S/0.1 M Na₂SO₃ as a sacrificial additive, the activity of all Cd_1–xZn_xS photocatalysts significantly increased, reaching a maximum of 7.0 mmol g^–1 h^–1 in the presence of Cd_0.3Zn_0.7S. The deposition of 1% TiO₂ on Cd_0.3Zn_0.7S by mixing in acetone made it possible to synthesize a highly effective composite with an activity of 8.3 mmol g^–1 h^–1, which corresponds to the world level. A key result is confirmation of the high stability of this composite in both organic and inorganic environments, opening up prospects for its practical application in photocatalytic hydrogen evolution.

High purity aluminas (HPA) are used extensively in a variety of applications, ranging from microelectronics to catalysis. Aluminum hydroxides are among the primary raw materials for the production of aluminas, with microstructure (e.g. porosity), chemical makeup of the latter being to a significant extent inherited from the precursor. Present research demonstrates a novel use of the run-of-the-mill thermal analysis (TGA) data. We used kinetic mathematical modeling, as a tool to get insights into the structure of a series of high-purity bohemites (produced via alkoxide method) and pseudo-bohemites (nitrate-ammonia deposition). This approach, made it possible to obtain both quantitative (apparent dehydration kinetics, activation energy) and qualitative (porosity, preferential crystallites orientation) information on these samples. These characteristics serve as predictors of the future performance of the formed HPA catalytic carrier. We believe, that given the ubiquitous nature of TGA, this methodology can be of use for a wide range of readership working with bohemite and pseudo-bohemite type hydrated aluminas.