This study investigates the effects of feed gas composition (CO/H2, CO2/H2, or CO/CO2/H2) on the activity and selectivity of an Fe-based composite catalyst (20Fe/2K–2V/PVA) for the synthesis of oxygenates, specifically higher alcohols. Physicochemical characterization using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis revealed that feed gas composition governs the final phase composition of the active catalyst (χ-Fe5C2, Fe, Fe3O4). The highest yield of higher (C5+) alcohols (up to 3.4 g/m3), with carbon conversion of approximately 46

The catalytic activity of an iron–containing nanoscale chitosan-based catalyst in the Fischer–Tropsch synthesis (FTS) and the features of the formation of the structure of such a catalyst have been studied. It is shown that the nature of the acids used in the preparation stage—nitric, acetic or citric, has a significant effect on the structure obtained by partial destruction of chitosan and the size of the nanocrystallites of the active phase, which, in turn, leads to significant changes in the activity of the catalyst and productivity for the target products—C5+ hydrocarbons. The best performance of catalyst in FTS observed for the sample, obtained with use of nitric acid: С5+ productivity reached to 2136 g С5+/kgFe/h.

A sample of a catalytic system based on nickel and a carbon-containing material, microcellulose, was obtained using a hydrothermal synthesis method. A catalytic study of the synthesized system in the process of selective hydrogenation of carbon monoxide and carbon dioxide was carried out with calculation of the apparent activation energy. The sample was demonstrated to be highly active in the selective hydrogenation reactions of carbon oxides. A 100

Изучено влияние температуры гидротермальной карбонизации (190-250 °С) гидролизного лигнина на свойства получаемых биоуглей. Биоугли исследованы комплексом физико-химических методов, проведен их элементный, технический и термический анализ. Показано, что повышение температуры гидротермальной обработки лигнина отрицательно влияет на выход биоугля, но позволяет получить термически более стабильный продукт, имеющий топливные характеристики, сопоставимые с бурыми углями. The effect of hydrothermal carbonisation temperature (190-250 °C) on the properties of biochar produced from hydrolytic lignin was studied. Biochar was investigated using a set of physicochemical methods, its elemental, proximate and thermal analysis was carried out. It is shown that an increase in the temperature of hydrothermal treatment has a negative effect on biochar yield but allows obtaining a more thermally stable product with fuel characteristics comparable with those of brown coal.

The homogeneous acetic acid synthesis-type Ru–Co–Li/N-methylpyrrolidone catalyst for CO and H2 transformations has been studied at moderately high pressures. For 1CO:2H2, low acetic acid selectivity has been observed, along with remarkable methyl acetate selectivity, the absence of aldehydes and ethyl acetate and sharp deviations from the Anderson-Schultz-Flory distribution for both alcaohols and long-chain hydrocarbons. For 1CO:1H2 and slightly elevated pressure, acetic acid selectivity slightly increased, notable ethyl acetate formation was detected, and both long-chain hydrocarbons and alcohols disappeared. Hypotheses are discussed about the direct parallel formation of all observed product groups (hydrocarbons, alcohols, esters, and acetic acid) and hydrocarbon chain growth limitations according to the formed Ru–Co cluster size in the presence of the aforementioned catalytic system.

The work is concerned with the development of a new type of iron-containing catalyst (Ct) based on lignin for the hydrogenation of carbon monoxide. Catalytic systems were obtained by hydrothermal synthesis and studied using a set of physicochemical methods (Fourier Transform IR spectroscopy, Raman spectroscopy, low-temperaIt is shown that the formed catalysts are fine-grained, non-pyrophoric, non-hygroscopic, black powders. The catalytic systems are determined to exhibit high activity in carbon monoxide hydrogenation: the conversion is close to 100%, the productivity with respect to C(5+ )hydrocarbons reaches 131.6 g/(kg Ct center dot h).

The study investigates hydrogenation of CO 2 over mono- and bimetallic catalysts supported on biochar. In this reaction, bimetallic iron–cobalt catalysts were shown to surpass monometallic iron and cobalt catalysts in terms of catalytic performance. The optimal combination of performance parameters was reached at an iron to cobalt ratio of 3 : 1. The composition and genesis of the active phase in the bimetallic Fe–Co catalyst were identified, and the CO 2 hydrogenation mechanism was suggested for an iron-dominated bimetallic catalyst. Using biochar as a support was found to provide an active phase composition favorable for CO 2 hydrogenation.

Работа посвящена разработке нового типа железосодержащего катализатора (Кт) на основе лигнина для процесса гидрирования монооксида углерода. Каталитические системы получали методом гидротермального синтеза и изучали комплексом физико-химических методов (ИК-Фурье спектроскопия, спектроскопия комбинационного рассеяния, низкотемпературная адсорбция азота, элементный анализ, атомно-абсорбционный анализ, рентгенофазовый анализ, рентгеновская фотоэлектронная спектроскопия, просвечивающая электронная микроскопия). Показано, что сформированные катализаторы представляют собой мелкозернистый непирофорный негигроскопичный порошок черного цвета. Установлено, что каталитические системы проявляют высокую активность в процессе гидрирования монооксида углерода: конверсия близка к 100 %, производительность по углеводородам С5+ достигает 131.6 г/(кг Кт•ч). The work is concerned with the development of a new type of iron-containing catalyst (Ct) based on lignin for the hydrogenation of carbon monoxide. Catalytic systems were obtained by hydrothermal synthesis and studied using a set of physicochemical methods (Fourier transform IR spectroscopy, Raman spectroscopy, low-temperature nitrogen adsorption, elemental analysis, atomic absorption analysis, X-ray phase analysis, X-ray photoelectron spectroscopy, transmission electron microscopy). Brunauer-Emmett-Teller (BET) surface area analysis, elemental analysis, atomic absorption analysis, X-ray fluorescence (XRF), transmission electron microscopy (TEM). It is shown that the formed catalysts are fine-grained, non-pyrophoric, non-hygroscopic, black powders. The catalytic systems are determined to exhibit high activity in carbon monoxide hydrogenation: the conversion is close to 100 %, the productivity with respect to C5+ hydrocarbons reaches 131.6 g/(kg Ct ∙ h).

Описан процесс метанирования - селективного гидрирования оксидов углерода. Рассмотрены химические основы процесса и особенности формирования продуктов реакции в зависимости от используемого катализатора. Оценены преимущества каталитических систем на основе углеродных материалов и недостатки катализаторов на оксидных подложках для получения синтетического метана. Для процесса селективного гидрирования монооксида углерода (СО) предложены никельсодержащие углеродные катализаторы на основе березового активированного угля и микроцеллюлозы, полученные методами пропитки по влагоемкости и гидротермального синтеза. Синтезированные образцы исследованы методами оптико-эмиссионной спектроскопии с индуктивно-связанной плазмой, низкотемпературной адсорбции азота, сканирующей электронной микроскопии, энергодисперсионной спектроскопии, рентгенофазового анализа, термогравиметрического анализа. Изучено влияние подложки и метода синтеза катализатора на конверсию СО и выход метана в ходе реакции селективного гидрирования СО, выявлен оптимальный средний размер кристаллитов NiO и Ni(OH)2 - прекурсоров активной фазы. Показано, что наилучшие показатели конверсии монооксида углерода и выхода метана в реакции метанирования достигнуты в присутствии никельсодержащего углеродного образца на основе микроцеллюлозы, полученного методом гидротермального синтеза. Methanation process, or selective hydrogenation of carbon oxides, is described. The chemical foundations of the process and the features of the formation of reaction products are considered, depending on the catalyst used. The advantages of catalytic systems based on carbon materials and disadvantages of the catalysts on oxide substrates for the production of synthetic methane are evaluated. Nickel-containing carbon catalysts based on birch activated carbon and microcellulose were obtained by incipient wetness impregnation and hydrothermal synthesis, and proposed for the selective hydrogenation of carbon monoxide (CO). The synthesized samples were studied by optical emission spectroscopy with inductively coupled plasma, low-temperature nitrogen adsorption, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, thermogravimetric analysis. The influence of the substrate and the method of catalyst synthesis on CO conversion and methane yield from the selective hydrogenation of CO was studied, and the optimal size of NiO and Ni(OH)2 crystallites, the precursors or the active phase, was determined. It is shown that the best carbon monoxide conversion and methane yield from methanation reaction are achieved in the presence of nickel-containing microcellulose-based carbon sample obtained by hydrothermal synthesis.

Reducing the amount of CO2 in the atmosphere is a very important task. Therefore, the development and search for new approaches to the synthesis of catalytic systems, allowing for the catalytic conversion of CO2 into valuable products, is an urgent task. In this work, the catalyst was obtained by the thermolysis of a double complex compound. In this regard, kinetic studies of the parameters of the thermolysis process of double complex salts-[Co(NH)3]6][Fe(CN)6] were additionally determined using isoconversion and model approaches of non-isothermal kinetics. The catalyst was studied using various physicochemical methods—X-ray diffraction (XRD), infrared (IR)-spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). It was shown that, at the stage of catalyst preparation, the formation of a CoFe alloy occurred, while the surface mainly consisted of carbon in sp2-hybridization, and the metals existed in the form of spinel CoFe2O4. It was shown that catalysts based on bimetallic salts were active in the process of hydrogenation of carbon dioxide without a pre-activation stage (CO2 conversion reached 28%, with a specific activity of 4.0 µmolCO2/gMe·s). It was established that it was possible to change the selectivity of the carbon dioxide hydrogenation process by pre-treating the catalyst with hydrogen (selectivity for methane formation in the presence of an unreduced catalyst is 46.4–68.0%, whereas in the presence of a reduced catalyst it is 5.1–16.5%).

Supported iron catalysts based on a carbon-containing material, biochar obtained by the hydrothermal carbonization of biopolymers (cellulose and lignin), were studied. The catalytic systems showed high activity in the Fischer–Tropsch synthesis. A composition of C 5+ liquid products, uncharacteristic for iron-containing catalysts, characterized by high isoalkane content (up to 55%) was recorded. This fact was discussed in the context of the theory of bifunctional centers proposed by A.L. Lapidus with coworkers. It was suggested that the active centers of the test catalysts can be considered bifunctional (a carbide phase and an oxide phase). A correlation between the Fischer–Tropsch synthesis data on the test catalysts and the data obtained by Lapidus and coworkers on cobalt-containing catalysts was shown.

Methanation process, or selective hydrogenation of carbon oxides, is described. The chemical foundations of the process and the features of the formation of reaction products are considered, depending on the catalyst used. The advantages of catalytic systems based on carbon materials and disadvantages of the catalysts on oxide substrates for the production of synthetic methane are evaluated. Nickel-containing carbon catalysts based on birch activated carbon and microcellulose were obtained by incipient wetness impregnation and hydrothermal synthesis, and proposed for the selective hydrogenation of carbon monoxide. The synthesized samples were studied by optical emission spectroscopy with inductively coupled plasma, low-temperature nitrogen adsorption, scanning of the substrate and the method of catalyst synthesis on CO conversion and methane yield from the selective hydrogenation of CO was studied, and the optimal size of NiO and Ni(OH)2 crystallites, the precursors or the active phase, was determined. It is shown that the best carbon monoxide conversion and methane yield from methanation reaction are achieved in the presence of nickel-containing microcellulose-based carbon sample obtained by hydrothermal synthesis.

The effect of hydrothermal carbonisation temperature (190-250 C-degrees) on the properties of biochar produced from hydrolytic lignin was studied. Biochar was investigated using a set of physicochemical methods; its elemental, proximate and thermal analysis was carried out. It is shown that an increase in the temperature of hydrothermal treatment has a negative effect on biochar yield but allows obtaining a more thermally stable product with fuel characteristics comparable with those of brown coal.

Targeted synthesis of C/composite Ni-based material was carried out by the method of matrix isolation. The composite was formed with regard to the features of the reaction of catalytic decomposition of methane. The morphology and physicochemical properties of these materials have been characterized using a number of methods: elemental analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, temperature programmed reduction (TPR-H2), specific surface areas (SSA), thermogravimetric analysis, and differential scanning calorimetry (TGA/DSC). It was shown by FTIR spectroscopy that nickel ions are immobilized on the polymer molecule of polyvinyl alcohol, and during heat treatment, polycondensation sites are formed on the surface of the polymer molecule. By the method of Raman spectroscopy, it was shown that already at a temperature of 250 °C, a developed conjugation system with sp2-hybridized carbon atoms begins to form. The SSA method shows that the formation of the composite material resulted in a matrix with a developed specific surface area of 20 to 214 m2/g. The XRD method shows that nanoparticles are essentially characterized by Ni, NiO reflexes. The composite material was established by microscopy methods to be a layered structure with uniformly distributed nickel-containing particles 5–10 nm in size. The XPS method determined that metallic nickel was present on the surface of the material. A high specific activity was found in the process of catalytic decomposition of methane—from 0.9 to 1.4 gH2/gcat/h, XCH4, from 33 to 45% at a reaction temperature of 750 °C without the stage of catalyst preliminary activation. During the reaction, the formation of multi-walled carbon nanotubes occurs.

This review describes a process for methanation (selective hydrogenation) of carbon oxides with an emphasis on its importance for environmentally friendly and distributed energy generation. The drawbacks of oxide-supported catalysts and the advantages of carbon-based catalysts are assessed in terms of green chemistry principles. Catalysts based on carbon nanotubes, carbon nanofibers, and biomass derivatives are further discussed. Major research approaches are outlined for the implementation of carbon-based catalysts in selective hydrogenation of carbon oxides. This discussion suggests that the most promising catalysts for methanation are those based on biomass-derived carbon materials.

This review provides an analysis of recent scientific and engineering literature on chemical methods for CO2 processing using heterogeneous catalysts. The following major uses of carbon dioxide are discussed: exhaustive hydrogenation; synthesis of hydrocarbons including light olefins; synthesis of oxygenates; and production of cyclic carbonates. Furthermore, the paper highlights the main design approaches for CO2 conversion catalysts and formulates priorities for decarbonization using heterogeneous catalytic reactions .

Carbon materials were formed by the hydrothermal carbonization of cellulose, which were used as support for carbon dioxide hydrogenation catalysts (Fe/C and Fe-Mn/C). In the presence of these catalytic systems, CO2 conversion reached 50%. It is shown that the manganese introduction into the Fe-containing catalytic system significantly affects the distribution of gaseous С1-С4 products and liquid С5+ hydrocarbons. Promotion leads to the suppression of methane formation and an increase in the proportion of C2-C4 light olefins in gaseous products, as well as to intensification of secondary processes with the formation of a significant amount of iso-structures in liquid products. The different distribution of С1-С6 alcohols in the oxygen-containing products on the Fe/C and Fe-Mn/C catalysts indicates the manganese effect on the routes of their formation.

This article considers the catalytic and physicochemical properties of composite materials obtained by the heat treatment of nickel nitrate immobilized on polyvinyl alcohol (PVA). The effects of the composite formation temperature on the phase composition of the metal-containing particles and their size were studied. The composite material obtained was found to be an active catalyst for the hydrogenation of carbon monoxide without a pre-activation step. The following synthesis parameters were achieved: 29% carbon monoxide conversion under conditions for catalytic hydrogenation and 28 g/m3 methane yield. Hypotheses were offered concerning the effect of particle size on the activity of the synthesized composite and an effect of the volume velocity on the carbon monoxide hydrogenation process parameters was demonstrated.

Hydrothermal carbonization of lignin was used to prepare a precursor of a carbon-containing support to obtain supported iron-containing catalysts for the hydrogenation of carbon monoxide. In the paper, the possibility of forming a carbon support prone to the deposition of metal ions was investigated. Deep structural transformations occurring in the polymer matrix of lignin were demonstrated by FTIR spectroscopy. The thermal stability of the support material was determined by thermal analysis in the region up to 400 °C. The formation of magnetite nanoparticles with a size of about 7‒8 nm at the stage of preliminary calcination of the metal-carbon system was shown by X-ray diffraction analysis (XRD). It was found that the resulting systems have high activity comparable to the activity of the system based on activated carbon: the conversion of carbon monoxide reached 98%, the yield of C5+ hydrocarbons reached 72 g/m3.