This work focuses on the comparison of H₂ evolution in the hydrolysis of boron-containing hydrides (NaBH₄, NH₃BH₃, and (CH₂NH₂BH₃)₂) over the Co metal catalyst and the Co₃O₄-based catalysts. The Co₃O₄ catalysts were activated in the reaction medium, and a small amount of CuO was added to activate Co₃O₄ under the action of weaker reducers (NH₃BH₃, (CH₂NH₂BH₃)₂). The high activity of Co₃O₄ has been previously associated with its reduced states (nanosized CoB_n). The performed DFT modeling shows that activating water on the metal-like surface requires overcoming a higher energy barrier compared to hydride activation. The novelty of this study lies in its focus on understanding the impact of the remaining cobalt oxide phase. The XRD, TPR H₂, TEM, Raman, and ATR FTIR confirm the formation of oxygen vacancies in the Co₃O₄ structure in the reaction medium, which increases the amount of adsorbed water. The kinetic isotopic effect measurements in D₂O, as well as DFT modeling, reveal differences in water activation between Co and Co₃O₄-based catalysts. It can be assumed that the oxide phase serves not only as a precursor and support for the reduced nanosized cobalt active component but also as a key catalyst component that improves water activation.

Ce_1−xZr_xO₂ oxides (x = 0.1, 0.25, 0.5) prepared via the Pechini route were investigated using XRD analysis, N₂ physisorption, TEM, and TPR in combination with density functional theory calculations. The Ni/Ce_1−xZr_xO₂ catalysts were characterized via XRD analysis, SEM-EDX, TEM-EDX, and CO chemisorption and tested in carbon dioxide methanation. The obtained Ce_1−xZr_xO₂ materials were single-phase solid solutions. The increase in Zr content intensified crystal structure strains and favored the reducibility of the Ce_1−xZr_xO₂ oxides but strongly affected their microstructure. The catalytic activity of the Ni/Ce_1−xZr_xO₂ catalysts was found to depend on the composition of the Ce_1−xZr_xO₂ supports. The detected negative effect of Zr content on the catalytic activity was attributed to the decrease in the dispersion of the Ni⁰ nanoparticles and the length of metal–support contacts due to the worsening microstructure of Ce_1−xZr_xO₂ oxides. The improvement of the redox properties of the Ce_1−xZr_xO₂ oxide supports through cation modification can be negated by changes in their microstructure and textural characteristics.

MnO_x-CeO₂, MnO_x-ZrO₂, MnO_x-ZrO₂-CeO₂ oxides with the Mn/(Zr + Ce + Mn) molar ratio of 0.3 were synthesized by coprecipitation method followed by calcination in the temperature range of 400–800 °C and characterized by XRD, N₂ adsorption, TPR, TEM, and EPR. The catalytic activity was tested in the CO oxidation reaction. It was found that MnO_x-CeO₂, MnO_x-ZrO₂-CeO₂, MnO_x-ZrO₂ catalysts, calcined at 400–500 °C, 650–700 °C and 500–650 °C, respectively, show the highest catalytic activity in the reaction of CO oxidation. According to XRD and TEM results, thermal stability of catalysts is determined by the temperature of decomposition of the solid solution Mn_x(Ce,Zr)_1−xO₂. The TPR-H₂ and EPR methods showed that the high activity in CO oxidation correlates with the content of easily reduced fine MnO_x particles in the samples and the presence of paramagnetic defects in the form of oxygen vacancies. The maximum activity for each series of catalysts is associated with the start of solid solution decomposition. Formation of active phase shifts to the high-temperature region with the addition of zirconium to the MnO_x-CeO₂ catalyst.

To achieve a high activity and coking stability of nickel catalysts in dry reforming of methane, materials comprised of ceria–zirconia doped by Ti were investigated as supports. Ceria–zirconia supports doped with titanium were prepared either via the Pechini method or by synthesis in supercritical alcohol media. Ni-containing catalysts were prepared by two techniques: standard incipient wetness impregnation and one-pot synthesis. The catalytic reaction of DRM to synthesis gas was carried out in the 600–750 °C range over 5% wt. Ni/Ce(Ti)ZrO₂. Dried and calcined supports and catalysts were characterized by physicochemical methods including N₂ adsorption, XRD, Raman, H₂-TPR, and HRTEM. Both preparation methods led to formation of solid solution with cubic fluorite-like structure, as well as after addition of Ti. Introduction of Ti should provide improved oxygen storage capacity and mobility of support oxygen. The highest activity was observed with the catalyst of 5% wt. Ni/Ce_0.75Ti_0.2Zr_0.05O_2−δ composition due to optimized oxide support structure and support oxygen mobility.

The development of solvent-free methods for the synthesis of catalysts is one of the main tasks of green chemistry. A nickel–alumina catalyst for CO₂ methanation was synthesized by solid-state combustion method using hexakis-(imidazole) nickel (II) nitrate complex. Using X-ray Powder Diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Hydrogen temperature-programmed reduction (H₂-TPR), it was shown that the synthesized catalyst is characterized by the localization of easily reduced nickel oxide on alumina surface. This provided low-temperature activation of the catalyst in the reaction mixture containing 4 vol% CO₂. In addition, the synthesized catalyst had higher activity in low-temperature CO₂ methanation compared to industrial NIAP-07-01 catalyst, which contained almost three times more hard-to-reduce nickel–aluminum spinel. Thus, the proposed approaches to the synthesis and activation of the catalyst make it possible to simplify the catalyst preparation procedure and to abandon the use of solvents, which must be disposed of later on.

The MnO_х-ZrO₂-CeO₂ oxide catalysts were synthesized by co-precipitation method with varying (1) Zr/Zr + Ce molar ratio at constant manganese content of 0.3; (2) manganese content at constant Zr/Ce molar ratio of 1; (3) Mn/Mn + Zr molar ratio at constant Ce content of 0.5. Catalysts are characterized by XRD, N₂ adsorption, TPR, and XPS. The catalytic activity of all the series was tested in the CO and propane oxidation reactions. In contrast to the variation of the manganese content, the Zr/Zr + Ce molar ratio does not significantly affect the catalytic properties. The dependence of the catalytic activity in CO oxidation on the manganese content has a «volcano» shape, and the best catalytic performance is exhibited by the catalyst with Mn/(Zr + Ce) = 1. In the case of propane oxidation reaction, there is «sigma» like dependence, activity increases with increase of Mn/(Mn + Zr + Ce) molar ratio up to 0.3, stabilizing with a further increase in the manganese content. XRD and XPS have shown that with an increase of the Mn concentration in the MnO_x-ZrO₂-CeO₂ catalysts, the amount of crystalline manganese oxides such as Mn₂O₃ and Mn₃O₄, as well as the surface concentration of Mn cations, increases. While the content of Mn_xZr_yCe_1-x-yO₂ solid solution decreases, the concentration of manganese cations (x) in volume of Mn_xZr_yCe_1-x-yO₂ mixed oxide grows. The maximum activity in CO oxidation corresponds to the balance between the amount of the solid solution and the concentration of manganese cations in the volume of mixed oxide. The propane oxidation reaction is less sensitive to the state of manganese ion rather than to its amount. In this case, a decrease in the content of the Mn_xZr_yCe_1-x-yO₂ solid solution with increase in manganese amount in catalyst is compensated by an increase in content of crystalline manganese oxides and the surface concentration of manganese.