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.

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), w

The method of obtaining functional materials almost always influences the physicochemical properties of the resulting substances. The plasma treatment of solid materials is considered to be a more energy efficient method when compared with thermal destruction. Our work is the first to treat double complex salt (DCS) [Co(NH₃)₆][Fe(CN)₆] with different plasma discharge modes. We have demonstrated the possibility of obtaining a single-phase spinel with a CoFe₂O₄ structure as a result of the calcination in air of the plasma destruction product. The crystallite sizes of the obtained spinel are 40 nm, with a lattice constant 8.38 Å.

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.

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 C5+ liquid products, uncharacteristic for ironcontaining 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.