V. M. Vorotyntsev

PECVD synthesis of As–S glasses

Chalcogenide glasses of the As–S system were first obtained by melting of solid products of interaction between As and S in low-temperature argon plasma. The plasma-chemical synthesis was performed at a reactor wall temperature not exceeding 250°C. The content of S in the As–S glasses is 54 to 72 mol %. The elemental, phase, and impurity composition of the glasses and their glass-transition point and optical properties were studied.

Separation of Gas Mixtures by the Gas Hydrate Crystallization Method

Mathematical models are suggested for two modes of separating gas mixtures by gas hydrate crystallization. The separation efficiency is calculated for the sulfur hexafluoride–sulfur dioxide mixture. The models are checked against experimental data on the removal of Freon-12 from sulfur hexafluoride. The observed and calculated separation coefficients are in satisfactory agreement.

Ultrapurification of gases in a continuous membrane column cascade

Abstract The separation power of ultrapurification of gases in cascades of the continuous membrane column type was calculated. The equation for the degree of separation of the extraction and enrichment section was obtained. The total area of membranes in continuous membrane column cascades is compared with that of nonmixing multistage countercurrent cascades. The maximum degree of separation of a mixture of argon and propane as an impurity attained in the apparatus was 8.5×10 4 ,with 98% product extraction.

Influence of the preparation technique on the optical properties and content of heterophase inclusions of AS 2 S 3 chalcogenide glasses

Bulk samples of As-S chalcogenide glasses were prepared by an interaction of vapors of volatile precursors in low-temperature non-equilibrium plasma discharge (plasma enhanced chemical vapor deposition (PECVD process)). Elemental arsenic and sulfur (As + S), and arsenic monosulfide and sulfur (As4S4 + S) were used as initial substances. In parallel, the As-S bulk samples were synthesized by “traditional” melting of the initial substances in the evacuated quartz ampoule from the same precursors. The optical properties of the bulk samples were compared. The exhausted gas mixtures were analyzed to clarify the difference in carbon impurities content. 3D laser ultra microscopy was used to determine the content of heterophase inclusions in the samples.

Deep gas cleaning of highly permeating impurities using a membrane module with a feed tank

Deep gas cleaning of highly permeating impurities using a membrane module with a feed tank has been considered. Two modes of the process has been studied, one with a constant degree of separation in the membrane module and the other with a constant concentration of impurities in the stream directed to the receiver tank. The degree of removal and the time of the process have been calculated. It has been shown that the second mode is somewhat more cost-effective because of the lack of mixing of streams with different concentrations and the absence of the lost work of separation.

Gas mixtures separation by an absorbing pervaporation method

Abstract This article discusses the results of research on absorption and pervaporation processes in combination. The processes realize in the volume of one mass-exchange device. The separating characteristics of the hybrid process were compared with the gas separation membrane process. It is shown why the separation factor absorbing pervaporation essentially increases. The influence of different factors on a separation factor has been studied. The mathematical model well describes the gas mass transfer through the absorbent—membrane system.

Comparison of optical properties and impurities content of Ge-Sb-S-I glasses prepared by different methods

Bulk samples of Ge-Sb-S-I chalcoiodide glasses of different compositions were prepared by plasma enhanced chemical vapor deposition (PECVD). GeI4, SbI3 and elemental sulfur were the initial substances. Impurities content, optical, and structural properties of the samples were studied. The data obtained were analyzed and compared with the properties of the bulk samples prepared by interaction of the same initial substances into reactive-distillation column at 650°C. The dependence of optical properties of the glasses on preparation technique was discussed.

Quantum chemical simulation of the dissociative chemisorption of hydrogen on metal surfaces of nanoclusters

The mathematical and quantum chemical simulation of surfaces of Cd, Ba, Ca, Cu, Cs, Ti, Ni, Pd, W, and Pt metals was performed. The structural data were obtained for these surfaces, the behavior of a hydrogen molecule near these surfaces was studied. The calculations were performed in the framework of the density functional theory using the hybrid Becke—Lee—Yang—Parr functional in the LANL2DZ basis set. Mathematical modeling of the studied surfaces in the nanocluster approximation was performed by the Alexandrovich method. The results indicate that metals Ni, Pd, Pt, W, and Ti exhibit high catalytic activity in the dissociative chemisorption of hydrogen, while Ba, Cd, Cs, Ca, and Cu are lowly efficient because of the formation of hydrides.

Fine Purification of Silane for Removal of Chlorosilanes by Membrane Gas Separation

The membrane separation of a silane, dichlorosilane, trichlorosilane, and tetrachlorosilane gas mixture has been theoretically and experimentally studied. The ideal separation factors have been determined experimentally and their values in the separation cell at pressures P1 and P2 have been found. The separation factor has been calculated for different ratios of flows in the compartments of a membrane module. The silane cleaning process for the removal of highly penetrating impurities in a radial membrane module and in a membrane module with a feed tank has been calculated.

Nitrous oxide high purification by membrane gas separation

In this work the scope of nitrous oxide high purification by membrane gas separation was presented. The permeability values of nitrous oxide and its limiting impurities were measured for “Lestosil” membrane at feed pressure in the range from 100 to 400 kPa. The values of ideal selectivity were determined. It was shown that nitrous oxide is more permeable than impurities components. Therefore the process of nitrous oxide high purification was calculated for it carried out in membrane module with a feeding reservoir which is used for purification from low permeable impurities.