Yuri A. Lebedev

For the first time, results are presented demonstrating the feasibility of carbon dioxide disposal while simultaneously producing syngas using a microwave discharge in liquid methanol, with CO₂ bubbling at atmospheric pressure. The CO₂ input flow rate ranged from 100 to 700 mL/min, and the incident microwave power varied between 450 and 540 W. The main discharge products were H₂ and CO. The highest degree of carbon dioxide decomposition was 75%.

A direct-current discharge in a mixture of CO₂ and CH₄ at atmospheric pressure has been studied at different CO₂ to CH₄ feed ratios and different polarities of applied voltage. It has been shown that when the cathode is located in the gas inlet zone with a gas flow rate ratio of CO₂/CH₄ = 1 at the inlet, discharge sparking is observed, which is associated with the intensive formation of a solid phase from carbon-containing particles. The degree of decomposition of CH₄ is about 95%, and that of CO₂ is within 85–95%, decreasing with an increase in the CO₂ concentration in the mixture. The ratio of H₂ and CO concentrations at the discharge outlet can be controlled by the ratio of CO₂ and CH₄ inlet flow rates.

Ultrafine double oxides of zinc and copper were synthesized by a simple one-step method from nitrates under the action of low-temperature plasma of an atmospheric pressure glow discharge in air without organic substrates and surfactants. The treated nitrates were placed on the cathode of the discharge system. The properties of the plasma were investigated by emission spectroscopy in the visible region of the spectrum. The values of rotational and vibrational temperatures of nitrogen without nitrates and in the presence of nitrates were determined from the emission of the second positive nitrogen system. It is shown that the introduction of nitrates significantly decreases the rotational temperature of nitrogen molecules. The change in the spectral composition of radiation, when nitrates are introduced into the discharge, was investigated. The obtained samples were characterized using scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive analysis, and the gas component of the plasma was studied using emission spectroscopy. As a result of the interaction of plasma with zinc and copper nitrates, the corresponding zinc and copper oxides with the composition ZnO; CuO; ZnO_0.25CuO_0.75; ZnO_0.75CuO_0.25; ZnO_0.5CuO_0.5 were formed. The composition was confirmed by XRD and EDS data. The surface morphology was studied using a scanning electron microscope; the surface of the powders is well developed, and the particles have ellipsoidal shapes. Based on the emission spectra, possible mechanisms for forming oxides have been proposed. Presumably, the main contribution to the formation of oxide particles is made by ion bombardment of the cathode, followed by the transfer of nitrates into the gas phase, where they decompose to oxides.

Представлен новый метод получения сложных оксидов меди и цинка на поверхности цеолита марки NaX. Цеолиты погружали в водный раствор нитратов меди, цинка и их смеси (50:50) на несколько часов, после чего сушили в течение 1 сут. Цеолиты, покрытые нитратами, обрабатывали тлеющим разрядом атмосферного давления воздуха в течение 10 мин. Во время плазменной обработки изменялся цвет поверхности цеолитов. Изменение морфологии поверхности исследовали с помощью сканирующей электронной микроскопии. Показано, что на поверхности образуются сложные наноразмерные структуры, которые по данным энергодисперсионной рентгеновской спектроскопии представляют собой оксиды меди и цинка. Определение удельной площади поверхности и распределения пор по размерам показало, что плазменная обработка цеолитов с нанесенными на них нитратами ведет к уменьшению площади микропор и уменьшению мезопор. Фотокаталитическая активность проверялась на примере разложения стандартного красителя метиленовый синий. Так облучение ультрафиолетовым светом раствора метиленового синего в течение 180 мин раствора без цеолита не показало никакого изменения оптической плотности растворов, как и исследования, проведенные в условиях отсутствия какого-либо светового излучения. Показано, что после 180 мин воздействия света на раствор метиленового синего разложилось 70,3% красителя на цеолите с оксидом меди и 83,8 на цеолите с оксидом цинка. Наилучшие результаты показали образцы с цеолитами, покрытыми комплексным оксидом меди и цинка, где фоторазложение составило 87,9% за 180 мин облучения ультрафиолетовым светом. Для цитирования: Смирнова К.В., Лебедев Ю.А. Получение в тлеющем разряде на поверхности цеолитов оксидов цинка и меди для разложения метиленового синего. Изв. вузов. Химия и хим. технология. 2025. Т. 68. Вып. 9. С. 75-82. DOI: 10.6060/ivkkt.20256809.7118.

The electrical characteristics, emission spectra, and composition of gas products in a DC discharge mixture of CO ₂ and CH ₄ at different polarities of the applied voltage and an AC discharge (50 Hz) at atmospheric pressure and different ratios of CO ₂ and CH ₄ flow rates have been investigated. The best degree of CH ₄ decomposition is about 95%. The degree of CO ₂ decomposition ranges from 85%−95% at a CO ₂ /CH ₄ consumption ratio equal to one. The best characteristics of the decomposition process are obtained in a direct current discharge under conditions when the cathode is located in the part of the discharge tube opposite to the point of introduction of the gas mixture.

A chromatographic study of atmospheric pressure glow discharge products in a mixture of CO₂ and CH₄ has been carried out. The discharge has been ignited using a source at a frequency of 50 Hz and a discharge voltage of up to 10 kV. The main gas products at the discharge output are H₂ (∼55%) and CO (∼40%). It is shown that the discharge properties are determined by the ratio of CO₂ and CH4 consumption at the reactor input. Soot particles are formed in the discharge in addition to gas products at the same CO₂ and CH₄ consumption at the reactor input. The soot formation is suppressed and water vapor appears in the discharge when in the CO₂ content in the mixture increases. The discharge current and voltage oscillograms have been analyzed and the energy required to obtain hydrogen and spent on decomposition of СО₂ have been estimated.

This work is devoted to the numerical modeling of the reaction of methane conversion to acetylene under plasma-jet pyrolysis conditions and a comparison of the obtained results with the available experimental data. The calculations were performed within the framework of the ideal plug-flow reactor model for atmospheric pressure. The analysis of the main processes of methane decomposition and acetylene formation was carried out in cases where either hydrogen or methane was used as a plasma-forming gas. The results of calculations of the main products of methane decomposition (hydrogen and acetylene) agree quite well with the experimental data.

Gas chromatography was used to study the products of an atmospheric pressure microwave discharge in water with methane bubbling at incident microwave power ranging between 500 and 650 W and methane flow rate ranging between 25 and 75 mL/min. The main components of products are H₂, CO, CO₂, and CH₄. The concentration of H₂ reaches 75% with the energy consumption for hydrogen formation of 25 L/kWh. A zero‐dimensional self‐consistent nonstationary discharge model, which takes into account the process of quenching of reaction products, was developed to analyze experimental results and study mechanisms of the formation of hydrogen and carbon oxides. Taking into account the quenching of reaction products is an important and necessary part of modeling discharges in liquids.