Key words: aerogel, germanium oxide, doping, praseodymium, co-gelation, luminescence
A straightforward method for creating crystalline GeO2: Pr3+ aerogels is introduced. By adapting an existing epoxide-induced synthesis process, we successfully performed cogelation of GeCl4 and Pr(NO3)3 · 5H2O. It was shown show that the concentration of the dopant ion in the aerogel increases in direct proportion to its initial share in the mixture, with a uniform distribution throughout the material. The dependence of the photoluminescence of GeO2: Pr3+ aerogels on the excitation wavelength is established. At high excitation energies, the luminescence is completely determined by the germanium oxide matrix, while when excited by green light, the characteristic orange-red emission bands of Pr3+ ions become the dominant.
doi:10.34984/SCFTP.2025.20.4.001
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ГОСТ
7.0.100-2018
Co-Hydrolysis of GeCl<sub>4</sub> and Pr(NO<sub>3</sub>)<sub>3</sub> · 5H<sub>2</sub>O in an Aprotic Solvent — a Way to Create Aerogels with Target Luminescent Characteristics / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 4. – С. 3-19. - DOI: 10.34984/SCFTP.2025.20.4.001
TRANSLIT
Sovmestnyj gidroliz GeCl<sub>4</sub> i Pr(NO<sub>3</sub>)<sub>3</sub> · 5H<sub>2</sub>O v aprotonnom rastvoritele — put' k sozdaniyu aerogelej s zadannymi lyuminescentnymi harakteristikami / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 4. – S. 3-19. - DOI: 10.34984/SCFTP.2025.20.4.001
En
Co-Hydrolysis of GeCl<sub>4</sub> and Pr(NO<sub>3</sub>)<sub>3</sub> · 5H<sub>2</sub>O in an Aprotic Solvent — a Way to Create Aerogels with Target Luminescent Characteristics. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 4, 3-19 (2025). https://doi.org/10.34984/SCFTP.2025.20.4.001
Key words: supercritical fluid chromatography, enantiomers, chiral separation, semipreparative separation methods, analytical separation methods, ibuprofen, ketoprofen
Highly efficient analytical methods for separating racemic mixtures of ibuprofen and ketoprofen with supercritical fluid chromatography (SFC) have been developed using a chiral stationary phase based on amylose and supercritical carbon dioxide in combination with a co-solvent as a mobile phase. Optimum values of the resolution and selectivity for each pair of enantiomers have been achieved both in the isocratic and gradient modes. It has been revealed that the separation efficiency significantly depends on the co-solvent content in the mobile phase. The possibility of scaling the developed methods for semipreparative analysis has been assessed.
doi:10.34984/SCFTP.2025.20.4.002
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ГОСТ
7.0.100-2018
Development of a Semi-Preparative Method for Chiral Separation of Ibuprofen and Ketoprofen Racemic Mixtures by Supercritical Fluid Chromatography / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 4. – С. 20-25. - DOI: 10.34984/SCFTP.2025.20.4.002
TRANSLIT
Razrabotka polupreparativnogo sposoba hiral'nogo razdeleniya racemicheskih smesej ibuprofena i ketoprofena metodom sverhkriticheskoj flyuidnoj hromatografii / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 4. – S. 20-25. - DOI: 10.34984/SCFTP.2025.20.4.002
En
Development of a Semi-Preparative Method for Chiral Separation of Ibuprofen and Ketoprofen Racemic Mixtures by Supercritical Fluid Chromatography. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 4, 20-25 (2025). https://doi.org/10.34984/SCFTP.2025.20.4.002
Key words: carbon dioxide, hydrogenation, hydrocarbons, olefins, CO2 reduction, ironcontaining catalyst, potassium, Fischer—Tropsch synthesis
The regularities of carbon dioxide hydrogenation on a Fe-containing catalyst supported on a carbon carrier was studied in the temperature range of 250—400 °C at a pressure of 0.1 and 8.5 MPa. During the CO2 hydrogenation at 0.1 MPa, only CO is formed. At 8.5 MPa, a deeper hydrogenation of CO2 occurs with hydrocarbons formation (the value of the chain growth probability coefficient α = 0.54—0.65), the selectivity to which increases with increasing temperature. The best results for hydrocarbon formation were obtained at 8.5 MPa and 400 °C, with the C2—C4 olefin-to-alkane ratio reaching 1.6.
doi:10.34984/SCFTP.2025.20.4.003
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ГОСТ
7.0.100-2018
Effect of Pressure on CO<sub>2</sub> Hydrogenation on a Catalyst Containing Iron on a Carbon Support / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 4. – С. 26-33. - DOI: 10.34984/SCFTP.2025.20.4.003
TRANSLIT
Vliyanie davleniya na gidrirovanie CO<sub>2</sub> na katalizatore, soderzhashchem zhelezo na uglerodnom nositele / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 4. – S. 26-33. - DOI: 10.34984/SCFTP.2025.20.4.003
En
Effect of Pressure on CO<sub>2</sub> Hydrogenation on a Catalyst Containing Iron on a Carbon Support. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 4, 26-33 (2025). https://doi.org/10.34984/SCFTP.2025.20.4.003
Key words: palladium, hexafluoroacetylacetonate, supercritical carbon dioxide, transition metals, catalysts, silica gel, acetylene, hydrogenation, selectivity
The kinetics of acetylene hydrogenation in the presence of supported catalysts containing transition metals (Fe, Co, Ni, Cu, Ag) and palladium was studied. The catalysts were prepared by deposition of palladium hexafluoroacetylacetonate from its solution in supercritical carbon dioxide onto a silica-based support, followed by heat treatment and reduction in a hydrogen flow at 500 °C. The support was pre-impregnated with solutions of transition metal nitrates. The catalytic properties of the bimetallic systems were compared with monometallic systems containing the same components. The mutual influence of palladium and the transition metal on their catalytic properties was demonstrated. A change in the kinetics of the formation of acetylene hydrogenation products (ethylene and methane) with increasing temperature was revealed, manifesting itself differently on bimetallic catalysts containing Cu and Ag and on Fe-, Co-, and Ni-containing catalysts. In the second case, a minimum acetylene conversion rate is observed at temperatures around 100 °C, while the selectivity for ethylene formation increases sharply at further temperature rise. The observed patterns are interpreted from the point of view of the existence on the surface of complex multicomponent catalytic systems of various forms of adsorption of reactants (hydrogen and unsaturated hydrocarbons), differing in adsorption strength and reactivity.
doi:10.34984/SCFTP.2025.20.4.004
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ГОСТ
7.0.100-2018
Catalytic Properties of Silica-Supported Monometallic and Palladium-Containing Bimetallic Catalysts in Selective Hydrogenation of Acetylene / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 4. – С. 34-49. - DOI: 10.34984/SCFTP.2025.20.4.004
TRANSLIT
Kataliticheskie svojstva nanesennyh na oksid kremniya monometallicheskih i soderzhashchih palladij bimetallicheskih katalizatorov v reakcii selektivnogo gidrirovaniya acetilena / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 4. – S. 34-49. - DOI: 10.34984/SCFTP.2025.20.4.004
En
Catalytic Properties of Silica-Supported Monometallic and Palladium-Containing Bimetallic Catalysts in Selective Hydrogenation of Acetylene. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 4, 34-49 (2025). https://doi.org/10.34984/SCFTP.2025.20.4.004
Key words: supercritical fluid, solubility of supercritical fluid in hydrocarbons, empirical dependence, equation of state
A method is proposed for describing the solubility of supercritical fluids in hydrocarbons using empirical parameters determined by the error function minimization method. The solubility of supercritical CO2 in cyclohexane and kerosene at 313 K at various pressures is calculated. The standard deviation of the calculated data from the experimental ones according to the proposed method was no more than 8.2%.
doi:10.34984/SCFTP.2025.20.4.005
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ГОСТ
7.0.100-2018
Description of the Solubility of Supercritical Fluid in Hydrocarbons over a Wide Range of Pressures and Temperatures / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 4. – С. 50-56. - DOI: 10.34984/SCFTP.2025.20.4.005
TRANSLIT
Opisanie rastvorimosti sverhkriticheskogo flyuida v uglevodorodah v shirokom intervale davlenij i temperatur / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 4. – S. 50-56. - DOI: 10.34984/SCFTP.2025.20.4.005
En
Description of the Solubility of Supercritical Fluid in Hydrocarbons over a Wide Range of Pressures and Temperatures. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 4, 50-56 (2025). https://doi.org/10.34984/SCFTP.2025.20.4.005
Key words: supercritical CO2, hydrothermal fractionation, lignin, coconut fiber, extraction
A new approach to fractionation of coconut fiber by the hydrothermal method using ethanol and supercritical (SC) CO2 as co-solvents is proposed. The efficiency of the method for isolating valuable components due to the synergistic effect of hydrothermal treatment and increased solubility of biomass in the ethanol—water—SC CO2 system is demonstrated. During the 15 minute treatment at 110 °C, 12 MPa, and a fiber-to-ethanol mass ratio of 1 : 20, the maximum lignin yield (65 %) was reached, which is more than 2 times higher than during hydrothermal extraction with ethanol addition (26 %). The conservation of carbonyl groups and the native ratio of G (guaiacil) and S (syringyl) structural units in isolated lignin in accordance with the literature data has been shown by IR- and NMRspectroscopy.
doi:10.34984/SCFTP.2025.20.4.006
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ГОСТ
7.0.100-2018
Hydrothermal Extraction of Coconut Fiber Components in the Presence of Ethanol and Supercritical Carbon Dioxide / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 4. – С. 57-67. - DOI: 10.34984/SCFTP.2025.20.4.006
TRANSLIT
Gidrotermal'naya ekstrakciya komponentov kokosovogo volokna v prisutstvii etanola i sverhkriticheskogo dioksida ugleroda / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 4. – S. 57-67. - DOI: 10.34984/SCFTP.2025.20.4.006
En
Hydrothermal Extraction of Coconut Fiber Components in the Presence of Ethanol and Supercritical Carbon Dioxide. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 4, 57-67 (2025). https://doi.org/10.34984/SCFTP.2025.20.4.006
Key words: CaSn(OH)6, CaSnO3, solid-phase mobility, supercritical water fluid, molecular dynamic simulation, DFT
Unlike the traditional hydrothermal method, when the components interact in a solution, under processing a mixture of oxide powders in water vapor or supercritical fluid, the products are formed by solid-phase interaction of the reagents. Treatment of tin and calcium oxides in an autoclave under subcritical water vapour (270 °C) leads to the formation of CaSn(OH)6 crystals, and under supercritical water (400 °C) — to the formation of CaSnO3 crystals. The mechanism of solid-phase mobility during the formation of new phases in water fluid medium is discussed. The interaction of CaSn(OH)6 with water at 25 and 270 °C was simulated by molecular dynamics using DFT calculated potential function.
doi:10.34984/SCFTP.2025.20.4.007
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ГОСТ
7.0.100-2018
Mechanism of Calcium Stannates Crystallization in Sub- and Supercritical Water Fluid / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 4. – С. 68-78. - DOI: 10.34984/SCFTP.2025.20.4.007
TRANSLIT
Mekhanizm kristallizacii stannata kal'ciya v sub- i sverhkriticheskom vodnom flyuide / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 4. – S. 68-78. - DOI: 10.34984/SCFTP.2025.20.4.007
En
Mechanism of Calcium Stannates Crystallization in Sub- and Supercritical Water Fluid. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 4, 68-78 (2025). https://doi.org/10.34984/SCFTP.2025.20.4.007
Key words: hydrargillite, boehmite, transformation in an aqueous medium, solid-phase mobility of the structure, quasi-equilibrium, nucleation, self-adsorbed layer, self-organization
The kinetics of the isothermal transformation of hydrargyllite with a 3.5 microns average particle size into boehmite in the course of autoclave treatment at 160—180 °C has been studied in a liquid water and steam media. Samples of hydrargillite were used with and without the addition of boehmite previously obtained at 200 °C. It was found that when boehmite is added to hydrargillite, the induction period decreases, and the rate of boehmite formation does not change. In a water vapor medium, the induction period is sharply reduced and the rate of boehmite formation increases compared to the process in liquid water. A study of the morphology of the transformation products has shown that the formation and growth of boehmite crystals occurs on the surface of hydrargillite particles. The values of the activation energy 89.3±11.2 kJ/mol and 147.6±11.4 kJ/mol were determined by the temperature dependence of the constants of the isothermal rate of boehmite formation in liquid water and steam, respectively. The mechanism of transformation of hydrargillite into boehmite is discussed.
doi:10.34984/SCFTP.2025.20.4.008
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ГОСТ
7.0.100-2018
Kinetics of Hydragylite to Boehmite Transformation in Water and Water Vapor / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2025. – Т. 20. – № 4. – С. 79-101. - DOI: 10.34984/SCFTP.2025.20.4.008
TRANSLIT
Inducirovannoe prevrashchenie gidrargillita v byomit v vode i vodyanom pare / – Tekst : neposredstvennyj // Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2025. – Т. 20. – № 4. – S. 79-101. - DOI: 10.34984/SCFTP.2025.20.4.008
En
Kinetics of Hydragylite to Boehmite Transformation in Water and Water Vapor. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 4, 79-101 (2025). https://doi.org/10.34984/SCFTP.2025.20.4.008