The development of efficient CO2 capture methods is crucial both for solving the problem of decarbonization and for maintaining the air composition in closed life support systems. Regenerable K2CO3-based sorbents provide reversible CO2 sorption. However, their efficient operation requires the use of porous carriers that ensure the dispersion of the active component and increase the sorption rate. Carbon nanotubes (CNTs) are a promising carrier due to their high specific surface area, chemical and thermal stability. This work synthesizes regenerable K2CO3/CNT sorbents and investigates their sorption properties under conditions simulating CO2 removal in life support and decarbonization systems. A maximum sorption capacity of 15 wt. % for CO2 was achieved with a sorbent containing 71 wt. % K2CO2. The obtained regenerable materials have stable sorption capacity over multiple sorption-regeneration cycles, which opens up prospects for their practical application.

A comparative analysis of studies devoted to the development of approaches to determining key criteria for conducting a feasibility study on the prospects of innovative technologies for carbon dioxide capture, storage and utilization, mainly carried out over the past 10 years, has been carried out. It has been established that the main components of such an assessment are: the level of technology availability, the duration of its life cycle and the so-called carbon footprint, which in turn correlates with the magnitude of the global warming potential. It is shown that for CO2 production models, the key indicators are: a) technical (technology availability, operating temperatures, operating pressures, total CO2 conversion, life cycle assessment); b) economic (CAPEX capital costs, OPEX operating costs, total production cost, product price, etc.); c) environmental (electricity consumption, net CO2 utilization, carbon footprint, water consumption, etc.). The leading countries in the development of these technologies are the USA, Great Britain and Canada.

X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to reveal the role of Rh₂O₃ oxides and reaction of NH₃ molecules with rhodium oxide oxygen in the formation of etching layer on Rh during NH₃ oxidation with air over polycrystalline rhodium (Rh(poly)) at 1133 K. The oxidation of NH₃ on Rh(poly) is accompanied simultaneously by the intense oxidation of rhodium and the reaction of NH₃ molecules with Rh oxide oxygen. According to XPS, NH₃ oxidation on Rh(poly) leads to the formation of oxide layers with the composition Rh₂O₃. XRD data give close values for FCC lattice parameter a of metallic rhodium (3.802−3.803 Å) and coherent scattering region (CSR) D (39−55 nm) for all the samples. These data indicate oxide layers on metallic Rh, which contains subgrains with the size of 39−55 nm. In the initial step of NH₃ oxidation (t ≤ 1 h), porous oxide agglomerates ca. 0.7 µm in size are formed and crystal Rh₂O₃ fibers 50−100 nm in diameter grow. A long-term oxidation of NH₃ (t ≥ 10 h) results in the formation of plate-like 0.5−1.0 µm oxide agglomerates, on which crystal  Rh₂O₃ pyramids 1−2 µm in height grow. The formation of these etching structures during NH₃ oxidation can occur via the gas phase according to the vapor-liquid-solid (VLS) mechanism.

This paper presents promising approaches to using methanol as a feedstock for producing valuable chemical products. Catalysts and technologies to produce dimethoxymethane, dimethyl oxalate, and dimethyl carbonate are discussed. This review may be of interest given the reduced methanol exports from Russia, with the aim of developing domestic methanol utilization technologies for producing valuable chemical compounds.

Recent years have seen not only by the widespread use of plastics in many industries but also by the growing importance of recycling and the search for alternative methods for plastic waste disposal. The work proposes the integration of plastic refining products into the hydrotreating process of traditional petroleum fractions. The effect of mono- (Y/ZSM-23) and bi-zeolite (Y+ZSM-23) sulfide NiMo catalysts on the hydrotreating process of feedstock comprising chlorine-containing thermolysis oil is studied. It is shown that all synthesized catalysts provide conversion of chlorine-containing compounds above 92%. It is found that zeolite-containing catalysts in the hydrotreating process affect the fractional composition of the obtained products due to cracking and isomerization reactions, contributing to an increase in the yield of light fractions. It is shown that the catalyst based on zeolite Y demonstrates the potential for its application due to its high activity in the conversion of heteroatomic compounds and high-boiling n-alkanes.

The objective of this study is to demonstrate the relationship between reactor inlet pressure fluctuations and the spatial structure of a fluidized bed using a 50,000 t/year wastewater sludge oxidation reactor as an example. A tubular collector is used to fluidize the bed in the reactor, for which similar data are not available in the literature. The study was conducted using three-dimensional numerical modeling. Inlet pressure monitoring data and reactor bed video recordings were used for comparison with calculations. It is shown that pressure fluctuations at the reactor inlet and at various points along the bed height correlate, with the degree of correlation decreasing with distance from the reactor inlet. Spectral analysis of inlet pressure fluctuations revealed a coincidence of the main oscillation frequencies in the range of 0.8–1.0 Hz in both calculations and experiments. A comparison of the bed surface dynamics between calculations and experiments revealed that the process of large bubble formation, which underlies the hydrodynamic pattern in the bed, is similar in both calculations and experiments. Information on the degree of correlation between inlet pressure variations and the fluidized bed structure is useful for determining the current state of the catalyst bed, which contributes to reliable control of the reactor and the process as a whole.