Sergei V. Zelentsov

We considered reactions of the hydrogen atom transfer between arsines and triplet nitro compounds ¹XAsH₂ + ³YNO₂ → ³[XAsH…H…ONOY] → ²XAsH^. + ²HONOY. In our case X = H, CH₃, Ph, and Y = H, CH₃, Ph. In the cases of all arsine and nitro compounds we obtained similar characteristics, for example, arsine—bond (As-H) = 1.574 Å, bond (O-H) = 1.573 Å, angle (As-H-O) = 162.555-degree, atomic spin density (As) = 0.2931, atomic spin density (H) = −0.0425, atomic spin density (O) = −0.6895, and activation energy = 4.79 kCal/mol. Methyl arsine and phenyl arsine have a shorter bond between arsenic and hydrogen and a longer bond between oxygen and hydrogen than in the arsine case. We did not find any difference between HNO₂ and CH₃NO₂ geometries of the transitional states. Nitro phenyl has a shorter bond between arsenic and hydrogen and a longer bond between oxygen and hydrogen than in the case of arsine. Spin density donor substituents at the arsenic atom make bond As-H longer, but donor substituents at the nitrogen atom make bond O-H shorter. If X or Y was Ph, then atomic spin density on the hydrogen atom would be raised, but still remain negative. X and Y had the same influence on atomic spin density (H). Results were obtained by method ZOOM-NEB-TS wB97XD/def2-TZVP of the ORCA program.

To accelerate the transition to sustainable energy, efficient methods for CO₂-free hydrogen production and carbon utilization are needed. This study presents a new, sustainable approach for the simultaneous production of hydrogen, valuable hydrocarbons, and functional carbon materials by converting methane in low-pressure microwave plasma. Compared to traditional methane reforming methods (such as steam reforming), our plasma-based process operates at low temperatures, eliminates direct CO₂ emissions, and enables the conversion of methane into three valuable products: (1) environmentally friendly hydrogen for fuel cells and energy storage systems, (2) a range of valuable organic products (C₂H₂, C₂H₄, C₂H₆), and (3) functional carbon films with self-improving catalytic properties. Optical emission spectroscopy (OES) and the Langmuir double probe method were used for plasma diagnostics, revealing an increase in the concentration of active species (CH, Hα, C₂) and electron temperature upon argon addition. The structure, morphology, and impurity composition of the deposited films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and inductively coupled plasma mass spectrometry (ICP-MS), respectively. Gas-phase byproducts were analyzed using gas chromatography–mass spectrometry (GC-MS). Argon addition at an Ar/CH₄ ratio of 1 leads to the formation of carbon films with a more ordered structure, as confirmed by XRD data, and improved surface morphology. It was established that argon, by effectively participating in the excitation and dissociation processes of methane molecules through energy transfer from metastable states and increased electron temperature, optimizes plasma–chemical reactions, promoting the deposition of higher-quality carbon coatings.

The primary products of fulvic acid thermolysis under microwave irradiation were studied using DFT quantum chemistry methods with BP86 and B3LYP potentials. The method of relaxation scanning of the most important process paths leading to the rupture of peripheral C–H, C–O and C–C bonds and the formation of atomic hydrogen, HO^• and ^•CO₂H radicals was used. Secondary processes lead to the formation of molecular hydrogen, water, and carbon dioxide, respectively.

High-purity aluminum is widely used in metallurgy, microelectronics and chemical synthesis. In this work, the method of carbothermic reduction of aluminum powder in a microwave plasma discharge with the formation of valuable organic products such as synthesis gas, acetylene and benzene was used. Al powder was studied by inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The yield of by-products was studied by gas chromatography equipped with a mass spectrometer, as well as optical emission spectroscopy of plasma discharge. High-purity aluminum powder reduced with the plasma was used to synthesize oxygen-free trimethylaluminum (TMA). For the first time, TMA was synthesized in one vacuum cycle without the system depressurizing to improve the purity of the final product. Trimethylaluminum was analyzed by gas chromatography, which confirmed that the main substance is ≥99.99% pure. Gas chromatography with a mass spectrometer was used to determine by-products and residual reaction products. Additionally, ICP-MS was used to confirm trace metal concentrations, achieving the 7N standard for ultra-high-purity materials.

Peat reserves are of great interest for various industries (energy, fuel, chemical, etc.). It is common practice to use pyrolysis to process such solid carbon-containing resources with the subsequent yield of fuel and valuable products. One of the environmentally and energetically favorable ways to degrade carbon-containing feedstock that is currently under development is microwave-assisted pyrolysis. Microwave radiation provides volumetric heating of the material, which significantly increases heating uniformity across the volume of the irradiated sample, providing greater efficiency of heat transfer and avoiding local overheating on the reactor surface. In the conducted study, a system was designed for the microwave processing of organic materials. The structural elements of the system are described, and a schematic showing pyrolysis product separation is presented. A prototype of the developed reactor was used to conduct experiments on degrading high-moor sphagnum peat of the Greko-Ushakovskoe deposit under mild pyrolysis conditions induced by microwave radiation. The component composition of reaction products was analyzed via chromatography-mass spectrometry and compared with the results of previous experiments using conventional thermal pyrolysis. More advanced processing of peat is performed under the conditions of microwave-assisted mild pyrolysis with a high yield of valuable products due to a more efficient heat transfer, uniform heating of the material, and the optimal reaction rate. The developed technology is shown to produce raw materials for a wide range of high-tech industrial productions. The prospects for the industrial use of the proposed microwave-assisted peat processing technology are discussed, specifically for the production of efficient hydrophobic sorbent.

A series of theoretical and experimental studies was carried out with the aim of a direct comparison of the thermal and microwave destruction of peat during pyrolysis. Different heating mechanisms in these processes were investigated in the framework of simulations conducted using a commercial 3D software package, CST Studio Suite, to define their specific features. Based on these simulations, identical reactors were constructed exploiting an electric element and a microwave complex as a heat source, and an experimental technique was developed that allows these processes to be correctly compared under similar conditions. Using these reactors based on different heat sources, comparative experiments on peat pyrolysis were performed, and the results of the theoretical analysis were confirmed. As a result, the advantages of microwave exposure were demonstrated to achieve a more uniform and deep fragmentation of peat, increase the reaction rate and reduce the processing time, with high energy efficiency accompanying this method. As part of the experiments, the yield of pyrolysis products was analyzed. During the microwave destruction of peat, a high gas output (up to 27%) was obtained, which allows for a further increase in the efficiency of this processing method when burning these gases. The conducted elemental analysis showed an increase in the percentage of carbon from about 50% to 78% after microwave processing, which can become a raw material for obtaining effective environmentally friendly sorbents. The prospects for creating industrial microwave complexes for processing organic materials are discussed.

The design of a technological complex for microwave processing of organic materials is proposed. The electrodynamic system of an oversized microwave reactor for low-temperature pyrolysis has been developed. The constructive elements of the complex that allow its continuous failure-free operation in conditions of high radiation intensity are described. Based on the prototype of the elaborated reactor, model experiments on microwave pyrolysis of peat were carried out. The elemental composition of the solid fraction was analyzed during the conducted experiments. The possibility of the efficiency enhancement of the proposed processing method and potential applications of the novel technology are discussed.

The uB3LYP/6-311g++(d,p) method in the gas phase was used to simulate the reaction of ethylene with ortho, meta, para methylnitrobenzene, chloronitrobenzene, (CCl₃)PhNO₂, (CF₃)PhNO₂ in the T₁ state, as well as determining the influence of the position of donor and acceptor substituents in the benzene ring on the activation energy of the reaction under study. It is established that during the reaction ethylene oxide and nitroso compound are formed.

In this paper, we studied the mechanism of the reaction of photochemical oxidation of alkynes by nitro compounds on the example of acetylene with HNO₂, CH₃NO₂, C₂H₅NO₂. The calculation was carried out using the program Gaussian 03 method B3PW91 with a basic set of 6-31g+(d). n the course of the work, the method of calculation and the reaction mechanism were determined, the geometry of the transition state and the activation energy were calculated.