Co–Mg catalysts for methane combustion were synthesized and studied, revealing the transformation of MgCo₂O₄ spinel into a CoO–MgO solid solution with oxygen release from the spinel lattice as the calcination temperature increased. Repeated heat treatment of the calcined solid solution at lower temperatures led to spinel regeneration with segregation of the solid solution phase. A TPR of the samples showed the presence of two characteristic peaks, the first of which relates to the transition of Co³⁺_Oh spinel to the Co²⁺_Oh structure of CoO, and the second to the reduction of CoO to Co°. The second peak was observed at 540–620 °C for samples calcined at temperatures below spinel decomposition, and for high-temperature samples at 900–1100 °C. Taking into account the identity of the structure of phases obtained in both cases, the formation of not a true CoO–MgO solid solution, but rather a mixture of ordered oxides (“pseudo-solid solution”) in the low-temperature region, was postulated. A study of the activity of the samples showed the high activity of the spinel systems and a linear relationship between the activation energy of methane oxidation and the heat treatment temperature.

In order to establish the formation patterns of the Co–Mg oxide system, samples with different Co:Mg ratios and heat treatment temperatures were synthesized and studied. A study of the samples confirmed the phase transition of Mg_xCo_2–xO₄ spinels into the corresponding solid solutions at 800–900 °C. The similarity of the formation patterns for different compositions is shown. The rocksalt oxide in low-temperature samples is an anion-modified paracrystalline phase that forms a “true” solid solution only upon spinel decomposition. The TPR profiles of the decomposed Co₃O₄ spinel show surface Co₃O₄ peaks and a wide peak corresponding to the well-crystallized CoO, while partial Co₃O₄ TPR up to 380 °C results in dispersed and amorphous CoO. The high-temperature non-stoichiometric samples are poorly reduced, indicating their low oxygen reactivity. Spinel reoxidation after heat treatment to 1100 °C by calcination at 750 °C showed complete regeneration for MgCo₂O₄–Co₃O₄ samples and its absence in case of an excess of MgO relative to stoichiometry.

In order to establish the formation patterns of the Co–Mg oxide system, samples with different Co:Mg ratios and heat treatment temperatures were synthesized and studied. Study of the sam-ples confirmed the phase transition of MgxCo2–xO4 spinels into corresponding solid solutions at 800–900 °C. The similarity of formation patterns for different compositions is shown. The rock-salt oxide in low-temperature samples is an anion-modified paracrystalline phase that forms a “true” solid solution only upon spinel decomposition. TPR profiles of decomposed Co3O4 spinel show surface Co3O4 peaks and a wide peak corresponding to well-crystallized CoO, while par-tial Co3O4 TPR up to 380 °C results in dispersed and amorphous CoO. High-temperature non-stoichiometric samples are poorly reduced, indicating their low oxygen reactivity. Spinel reoxidation after heat treatment to 1100 °C by calcination at 750 °C showed complete regenera-tion for MgCo2O4–Co3O4 samples and its absence in case of an excess of MgO relative to stoi-chiometry. Based on the data obtained, it can be concluded that the processes governing the formation of Co–Mg oxide systems are determined by both Co:Mg ratio and the heat treatment conditions, potentially providing the possibility of fine tuning for specific catalytic processes.

This study presents the results of an investigation of carbonate-containing sorbents for CO₂ capture with natural support materials—kaolin and calcium carbonate—at various loadings of the active phase of Na₂CO₃. The effects of the support type on the distribution of the active component, phase composition, and pore structure of the sorbents were studied. It was found that a Na₂CO₃ loading of 25 wt.% provides the best balance between sorption capacity and technological feasibility. The thermal stability and regeneration capacity of the sorbents were evaluated under high-temperature conditions, revealing high thermal stability of the Na₂CO₃/CaCO₃ system up to 1000 °C, along with its durability over multiple adsorption–desorption cycles. Kinetic studies on the Na₂CO₃/CaCO₃ sorbent using the shrinking core model demonstrated that the overall CO₂ chemisorption process is controlled by surface chemical reaction at temperatures below 50 °C. The obtained results demonstrate the high potential of CaCO₃-based sorbents for practical applications in low-temperature CO₂ capture technologies. A promising direction for the use of such sorbents within CCUS is the development of integrated systems, where CO₂ capture is combined with its conversion into valuable products (e.g., methane, methanol, formic acid) through catalytic processes.

This study focuses on the shaping of ZSM–5-based granules using conventional pseudoboehmite as well as aluminum hydroxynitrate precursors obtained by partial thermal treatment of Al(NO₃)₃·9H₂O. The starting materials and nitrate-derived precursors were characterized by X-ray diffraction, thermal analysis, infrared spectroscopy, scanning electron microscopy, and low-temperature nitrogen adsorption. Model pseudoboehmite systems were used to evaluate the effects of moisture, peptization equivalent, and HNO₃ concentration in the initial liquid portion on pore volume, apparent density, shrinkage, and axial and radial crushing strength. Acid peptization showed a strongly non-linear effect: small HNO₃ additions increased strength and densification, whereas excess acid promoted structural heterogeneity and granule disintegration during thermal treatment. Even at constant moisture and total acid dosage, strength depended markedly on the initial peptizer concentration. In unpeptized ZSM–5/pseudoboehmite composites, increasing zeolite content reduced pore volume but increased density and strength, indicating formation of a more compact framework. Aluminum hydroxynitrate precursors enabled effective shaping of ZSM–5-containing pastes, demonstrating their potential as alternative binder precursors, while the optimized pseudoboehmite systems provided the most favorable overall balance between porosity and mechanical stability.

Based on published data and experimental studies of formation regularities of aluminium hydroxide, a reproducible technique for synthesis of bayerite-structured aluminium hydroxide by precipitation was developed as a part of the creation of preparation technology of chromia-alumina dehydrogenation catalyst. A possibility of synthesis of high purity bayerite (above 90 wt.%) with different particle sizes depending on synthesis conditions was shown. A correlation between dispersion of the sediments and synthesis temperature was shown, the optimal precipitation temperature – which allows obtaining bayerite with a sufficiently large particle size and high purity – was found. Based on the experiments, a fundamental difference between technologies and products of precipitation by sodium hydroxide and aqueous ammonia was shown. The influence of duration of precipitation stages on the properties of sediments is analyzed from the standpoint of theory of relative supersaturation