Key words: brown and bituminous coals, anthracite, ignition, combustion, water-oxygen fluid
The results of a study on the oxidation of coals with varying degrees of coalification in an oxygen atmosphere and a water-oxygen fluid (oxygen excess coefficient 1.22—1.43) are presented. The experiments were carried out in the reactor heated at a constant rate (1 °C/min) to 550 °C. The temporal dependences of the temperature and pressure of the reaction mixtures indicate that the addition of water vapor to oxygen reduces the temperature of ignition of the coals and intensifies their combustion. This effect is most pronounced for coals with a high degree of coalification. At certain values of total heat release, coal oxidation in both O2 and H2O/O2 fluids proceeds via a thermal explosion mechanism. The influence of the composition of organic and mineral components of coals on their ability to ignite is discussed.
doi:10.34984/SCFTP.2025.20.3.001
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ГОСТ
7.0.100-2018
Features of Coal Combustion in an Oxygen Atmosphere and in a Water-Oxygen Fluid at High Pressure / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 8-21. - DOI: 10.34984/SCFTP.2025.20.3.001
TRANSLIT
Osobennosti goreniya uglej v atmosfere kisloroda i vodokislorodnogo flyuida pri povyshennom davlenii / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 8-21. - DOI: 10.34984/SCFTP.2025.20.3.001
En
Features of Coal Combustion in an Oxygen Atmosphere and in a Water-Oxygen Fluid at High Pressure. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 8-21 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.001
Key words: binary system, phase behavior, supercritical fluid state, extraction, process efficiency
The article presents the results of an experimental study of the phase behavior of the binary mixture «freon R404A-acetone»» carried out at temperatures of 356.15 K, 372.15 K and 392.15 K. I—II type of phase behavior according to the Williams classification is established. The article presents the results of a study of the supercritical fluid extraction process as applied to the problem of extracting acetone from its aqueous solution of 3.5% and 10 % concentration. In the process carried out at a temperature of 356.15 K (83 °C), an increase in the efficiency of the extraction process was established as the pressure approaches its critical value for the designated binary system.
doi:10.34984/SCFTP.2025.20.3.002
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ГОСТ
7.0.100-2018
Phase Behavior of the Binary System «Freon R404a - Acetone» and SCF Extraction of Acetone from an Aqueous Solution with Freon R404a / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 22-33. - DOI: 10.34984/SCFTP.2025.20.3.002
TRANSLIT
Fazovoe povedenie binarnoj sistemy «freon R404a – aceton» i SKF-ekstrakcionnoe izvlechenie acetona iz vodnogo rastvora freonom R404a / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 22-33. - DOI: 10.34984/SCFTP.2025.20.3.002
En
Phase Behavior of the Binary System «Freon R404a - Acetone» and SCF Extraction of Acetone from an Aqueous Solution with Freon R404a. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 22-33 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.002
Key words: supercritical carbon dioxide, oil and operational contaminants in pipelines
This article presents an environmentally friendly and cost-effective system for cleaning oil and operational contaminants from marine pipelines using supercritical carbon dioxide as a solvent. A process flow diagram for cleaning oil contaminants from pipelines with a cleaning efficiency of up to 97 % is described. Using a pi peline cleaning system using supercritical carbon dioxide as a cleaning agent simplifies the process of cleaning the internal surfaces of pipelines of various lengths, diameters, and configurations, significantly reduces repair and restoration time, reduces labor intensity, minimizes liquid oil-containing waste generated during cleaning, and reduces the material and energy costs of processing it.
doi:10.34984/SCFTP.2025.20.3.003
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ГОСТ
7.0.100-2018
Application of Supercritical Carbon Dioxide as an Alternative Solvent for Oil and Operational Contaminants in Pipelines of Ship Systems / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 34-41. - DOI: 10.34984/SCFTP.2025.20.3.003
TRANSLIT
Primenenie sverhkriticheskogo dioksida ugleroda v kachestve al'ternativnogo rastvoritelya maslyanyh i ekspluatacionnyh zagryaznenij truboprovodov sudovyh sistem / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 34-41. - DOI: 10.34984/SCFTP.2025.20.3.003
En
Application of Supercritical Carbon Dioxide as an Alternative Solvent for Oil and Operational Contaminants in Pipelines of Ship Systems. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 34-41 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.003
Key words: rapid expansion of supercritical fluid, micronization, solubility, active pharmaceutical ingredient, tablets
N-Butyl-N-methyl-1-phenylpyrrolo[1,2-a]pyrazine-3-carboxamide (GML-3) is a compound exhibiting both anxiolytic and antidepressant activity. Like most substances being developed as active pharmaceutical ingredients (API), it is practically insoluble in water, which may negatively affect its bioavailability and complicate tablet formulation. According to the Noyes—Whitney equation, solubilization of poorly water-soluble APIs may be achieved by increasing their contact surface area with the aqueous medium or by creating a supersaturated state in solution. The API surface area can be increased by micronization using the rapid expansion of supercritical solution (RESS) method. The solubility of GML-3 in CO2 allows its micronization via RESS and the development of tablets with micronized API. The aim of this study was to develop GML-3 tablets containing API micronized by RESS, with improved dissolution kinetics.
doi:10.34984/SCFTP.2025.20.3.004
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ГОСТ
7.0.100-2018
Study of the Effect of Micronization of N-butyl-N-methyl-1-phenylpyrrolo 1,2-A]pyrazine-3-carboxamide by Rapid Expansion of Supercritical Solution on the Dissolution Kinetics from Tablets / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 42-49. - DOI: 10.34984/SCFTP.2025.20.3.004
TRANSLIT
Issledovanie vliyaniya mikronizacii N-butil-N-metil-1-fenilpirrolo[1,2-A] pirazin-3-karboksamida metodom bystrogo rasshireniya sverhkriticheskogo flyuida na kinetiku rastvoreniya iz tabletok / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 42-49. - DOI: 10.34984/SCFTP.2025.20.3.004
En
Study of the Effect of Micronization of N-butyl-N-methyl-1-phenylpyrrolo 1,2-A]pyrazine-3-carboxamide by Rapid Expansion of Supercritical Solution on the Dissolution Kinetics from Tablets. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 42-49 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.004
Key words: Populus tremula L., aspen bark, supercritical fluid extraction, carbon dioxide, composition
Extracts from the aspen bark (Populus tremula L.) were obtained using supercritical (SC) fluid extraction with carbon dioxide at 313.15 and 333.15 K and pressures ranging from 15 to 35 MPa. Chromatography-mass spectrometry was used to determine the component of the CO2 extract of Populus tremula L., revealing a significant amount of fatty acids and their esters. Traditional liquid extraction with petroleum ether was found to be significantly less efficient than SC-CO2 extraction in terms of the content of steroidal and triterpenoid components of the aspen bark in the final product.
doi:10.34984/SCFTP.2025.20.3.005
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ГОСТ
7.0.100-2018
Extraction of the Bioactive Compounds from Aspen Bark (<i>Populus tremula</i> L.) by Supercritical Carbon Dioxide / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 50-63. - DOI: 10.34984/SCFTP.2025.20.3.005
TRANSLIT
Izvlechenie biologicheski aktivnyh soedinenij iz kory osiny (<i>Populus tremula</i> L.) sverhkriticheskim dioksidom ugleroda / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 50-63. - DOI: 10.34984/SCFTP.2025.20.3.005
En
Extraction of the Bioactive Compounds from Aspen Bark (<i>Populus tremula</i> L.) by Supercritical Carbon Dioxide. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 50-63 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.005
Key words: polymeric membranes, poly(1-trimethylsilyl-1-propyne), supercritical fluids, gas permeation, mechanical properties
The effect of SC-CO2 and SC-CHF3 treatment of poly(1-trimethylsilyl-1-propyne) [PTMSP] films on their mechanical properties and gas permeability was investigated. Treatment of PTMSP films in supercritical fluids (SCF) leads to a decrease in the elastic modulus (Young’s modulus, E) and an increase in the relative elongation at break (ε), which is especially pronounced when processing films under high pressure (35 MPa). It is shown that the permeability coefficients of films treated at a pressure of 150 MPa either remain at the level of the initial untreated film (time of treatment 3 hours) or decrease noticeably (time of treatment 20 hours). At the same time, treatment of the films at a higher pressure of 35 MPa leads to a noticeable increase in the permeability coefficients. Films treated with both SCFs have a noticeably lower rate of decrease in permeability coefficients over time compared to untreated PTMSP. Thus, in untreated film after 1 year of storage in air, the permeability coefficients for O2, N2 and CO2 decreased by 50—60 %, while in treated films, the decrease in permeability over the same period is 10—40 %. The permeability values after 1 year for the sample with the greatest increase in permeability after treatment in SCF are close to the level of the initial permeability values of the untreated film. Thus, the work shows that by varying the type of fluid and the mode of film treatment, it is possible to carry out structural modification of PTMSP and effectively influence both the level of permeability and stabilization of transport parameters over time.
doi:10.34984/SCFTP.2025.20.3.006
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ГОСТ
7.0.100-2018
Effect of Supercritical CO<sub>2</sub> and CHF<sub>3</sub> Treatment of PTMSP Films on Mechanical and Gas Transport Properties / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 64-76. - DOI: 10.34984/SCFTP.2025.20.3.006
TRANSLIT
Vliyanie obrabotki plenok PTMSP sverhkriticheskimi CO<sub>2</sub> i CHF<sub>3</sub> na mekhanicheskie i gazotransportnye svojstva / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 64-76. - DOI: 10.34984/SCFTP.2025.20.3.006
En
Effect of Supercritical CO<sub>2</sub> and CHF<sub>3</sub> Treatment of PTMSP Films on Mechanical and Gas Transport Properties. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 64-76 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.006
Key words: palladium, copper, hexafluoroacetylacetone, acetylene hydrogenation, bimetallic catalysts, supercritical CO2
The catalytic properties of palladium and palladium-copper composite deposited on γ-Al2O3 from a supercritical carbon dioxide (SC-CO2) medium have been studied in the reaction of selective hydrogenation of acetylene into ethylene. Palladium and copper complexes with hexafluoroacetylacetone were used as precursors of the active component. Acetylene hydrogenation was studied in a reaction mixture (in vol. %): 1.0 C2H2, 93.7 C2H4, 5.3 H2, simulating a mixture used in the industrial process of acetylene removal from ethylene obtained by pyrolysis of various hydrocarbons. It is shown that the Pd/Al2O3 sample obtained by deposition of palladium from a SC-CO2 medium with subsequent reduction in hydrogen has an «egg-shell» type of distribution of the active component — it is concentrated in a thin (about 0.07 ± 0.01 mm) outer layer of a spherical carrier granule with a diameter of ∼1 mm. In the case of the PdCu/Al2O3 composite, an uneven distribution of the deposited component is also observed, but to a considerable depth along the diameter of the pellet. The Pd/Al2O3 sample showed high activity and moderate selectivity in the hydrogenation of acetylene to ethylene. After crushing and loading the fraction of 0.2—0.4 mm into the reactor, the same sample shows higher selectivity while maintaining high activity. The PdCu/Al2O3 sample showed substantially lower activity and selectivity in the target process. The results obtained demonstrate a high sensitivity of the catalytic properties to the method of deposited palladium-containing systems synthesis and a significant effect of the transfer processes in the grain and in the catalyst layer on the parameters of the acetylene hydrogenation in an acetylene-ethylene mixture.
doi:10.34984/SCFTP.2025.20.3.007
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ГОСТ
7.0.100-2018
Catalytic Properties in the Reaction of Selective Hydrogenation of Pd Acetylene and Pd-Cu Composites Deposited on Aluminum Oxide from a Medium of Supercritical Carbon Dioxide / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 77-89. - DOI: 10.34984/SCFTP.2025.20.3.007
TRANSLIT
Kataliticheskie svojstva v reakcii selektivnogo gidrirovaniya acetilena Pd i Pd-Cu kompozitov, nanesennyh na oksid alyuminiya iz sredy sverhkriticheskogo CO<sub>2</sub> / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 77-89. - DOI: 10.34984/SCFTP.2025.20.3.007
En
Catalytic Properties in the Reaction of Selective Hydrogenation of Pd Acetylene and Pd-Cu Composites Deposited on Aluminum Oxide from a Medium of Supercritical Carbon Dioxide. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 77-89 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.007
Key words: polyimides, aerogels, polycondensation, chemical imidization, cyclizing agent, polymer gels supercritical fluids, supercritical drying
Two series of polyimide aerogels (PI AEs) based on 4,4'-oxidianiline (ODA) and two dianhydrides were synthesized: 3,3',4,4'-benzophenone tetracarboxylic acid (BTDA) and pyromellitic acid (PMDA) by low-temperature polycondensation in dimethylformamide monomers pairs (ODA—BTDA) and (ODA—PMDA) with the addition of a crosslinking agent — 1,2,3-tris-(4-aminophenyl)benzene (TAB), chemical in situ imidization in solution, and subsequent drying of the PI gel with a supercritical (SC) fluid — SC-CO2. PI AEs with a specific surface area up to Ss = 230 m2/g were obtained. The effect of the chemical structure of anhydride and the content of TAFB on the amount of shrinkage and Ss of synthesized PI AEs has been studied. The morphological structure of PI AEs has been studied by scanning electron microscopy. The Ss values for PI AEs obtained by drying with preliminary solvent replacement (DMFA) with acetone and without solvent replacement are compared. It has been shown that SK-drying without solvent replacement shows Ss higher values. Carrying out the SC drying stage without first replacing the solvent significantly reduces the total duration of the PI AEs production process.
doi:10.34984/SCFTP.2025.20.3.008
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ГОСТ
7.0.100-2018
Preparation and Properties of Polyimide Aerogels Based on 4,4'-oxydianiline and Dianhydrides of Benzophenone Tetracarboxylic and Pyromellitic Acids / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 90-102. - DOI: 10.34984/SCFTP.2025.20.3.008
TRANSLIT
Poluchenie i svojstva poliimidnyh aerogelej na osnove 4,4'-oksidianilina i diangidridov 3,3',4,4'-benzofenontetrakarbonovoj i piromellitovoj kislot / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 90-102. - DOI: 10.34984/SCFTP.2025.20.3.008
En
Preparation and Properties of Polyimide Aerogels Based on 4,4'-oxydianiline and Dianhydrides of Benzophenone Tetracarboxylic and Pyromellitic Acids. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 90-102 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.008
Key words: carbon dioxide, N- izopropilakrilamid (NIPAM), NTBA, AIBN, solubility, gas expanded liquids, solubility isotherms
The solubility isotherms of N-tert-butylacrylamide (NTBA) monomer and azobisisobutyronitrile (AIBN) initiator for radical polymerization in carbon dioxide at temperatures and pressures ranging from 0.1 to 40.0 MPa and 305.0 to 353.2 K were determined using synthetic visual methods. The maximum concentrations of NTBA and AIBN at these conditions were determined. The phase behavior patterns of low-molecular weight compounds with low melting points in CO2 were discussed. It’s shown that AIBN solubility doesn’t limit the range of conditions for the polymerization process using NTBA.
doi:10.34984/SCFTP.2025.20.3.009
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ГОСТ
7.0.100-2018
Solubility of N-<i>tert</i>-butylacrylamide and Azobisisobutyronitrile in Carbon Dioxide / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 3. – С. 103-110. - DOI: 10.34984/SCFTP.2025.20.3.009
TRANSLIT
Rastvorimost' N-<i>tret</i>-butilakrilamida i dinitrila azobisizomaslyanoj kisloty v diokside ugleroda / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 3. – S. 103-110. - DOI: 10.34984/SCFTP.2025.20.3.009
En
Solubility of N-<i>tert</i>-butylacrylamide and Azobisisobutyronitrile in Carbon Dioxide. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 3, 103-110 (2025). https://doi.org/10.34984/SCFTP.2025.20.3.009