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2022, №4

сс. 3-13

Articles

Key words: wastewater, phenol, acetone, supercritical fluid extraction, carbon dioxide, propane-butane mixture, phase behavior, «CO2-acetone» system

An analysis of the phase behavior of binary systems that include organic components (phenol and acetone) and potential extractants (carbon dioxide and propane-butane mixture), which are supposed to be used in the supercritical state to treat the industrialwastewater runoff of «Êazanorgsintez» PJSC, is presented. The study of the phase behavior of the thermodynamic system «CO2-acetone» in the near-critical region of the state (313 K) was carried out using a high-pressure optical cell. Various phase states are fixed, including areas of critical opalescence and boundless miscibility for this binary system. The results of using the supercritical fluid extraction method for purification of a model aqueous solution of phenol and acetone with concentrations corresponding to industrial waste are presented.

doi: 10.34984/SCFTP.2022.17.4.001

2022, №4

сс. 14-31

Articles

Key words: supercritical antisolvent precipitation, crystallization, morphology, dicarboxylic acids, solubility in supercritical fluids

It is shown that the yield of supercritical antisolvent micronization (SAS) can be used for qualitative assessment of the solubility of substances in CO2-solvent mixtures. The limitations of this approach are shown and recommendations are given to increase the accuracy of such assessment. The influence of the degree of supersaturation on the morphology and particle size of malonic and succinic acids micronized by the SAS method is investigated. The possibility of obtaining α-succinic acid by the SAS method is demonstrated.

doi: 10.34984/SCFTP.2022.17.4.002

2022, №4

сс. 32-43

Articles

Conformational analysis of flufenamicт acid in SC-CO2 by 2D NOES

K.V. Belov, A.A. Dyshin, M.A. Krestyaninov, V.V. Sobornova, I.A. Khodov, M.G. Kiselev.

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Key words: supercritical fluid, flufenamic acid, phenamates, conformers, 2D NOESY

The results showed possibilities of nuclear Overhauser effect spectroscopy (NOESY) for conformational analysis of fenamates molecules (e.g. flufenamic acid). It has been established that the proportions of conformer groups were changed up to 32 % upon transition from a system with pure DMSO to a solvent based on SC-CO2 with the addition of 2 mol. % DMSO. The results of the study can be applied to control the conformational equilibrium of small drug-like molecules using supercritical fluids for slightly soluble compounds. This information is a high potential useful for fenamates micronization by the RESS, SAS, and DELOS methods.

doi: 10.34984/SCFTP.2022.17.4.003

2022, №4

сс. 44-53

Articles

Solubility of sulfur in a supercritical propane-butane mixture

T.R. Bilalov, I.Sh. Khabriev, V.F. Khairutdinov, T.R. Akhmetzyanov, F.M. Gumerov.

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Key words: sulfur, supercritical propane/butane mixture, phase equilibrium, solubility, thermodynamic model, Рeng-Robinson equation

The results of an experimental study of the phase equilibrium of the sulfur-propane/butane system carried out in the temperature range 403-443 K and pressure range 5.3-24.5 MРa using a high-pressure optical cell are presented. The V type of phase behavior is established. The solubility of sulfur in a supercritical propane-butane mixture under the above mentioned thermodynamic conditions is estimated based on the characteristics of the vapor branch of the phase equilibrium of the sulfur-propane/butane system and described using the Рeng-Robinson equation of state in combination with the rule of combining Mukhopadhyay and Rao. It has been established that the propane-butane mixture in the SCF state, along with good extraction properties, allows for the desulfurization of commercial hydrocarbons. Reducing the pressure from 25 to 7 MРa makes it possible to reduce the sulfur content at the 413 K isotherm by two times, at the 443 K isotherm by 10 times.


doi: 10.34984/SCFTP.2022.17.4.004

2022, №4

сс. 54-70

Articles

Key words: solubility, Chrastil’s equation, supercritical carbon dioxide, co-solvent, hydroxybenzoic acids, molecular dynamics

The paper studies the possibility of using reparametrized Chrastil’s equations to calculate the solubility of polar organic compounds in pure and cosolvent-modified supercritical carbon dioxide based on molecular dynamics simulation. Molecular dynamics simulation of solutions ortho-, meta- and para-hydroxybenzoic acids in pure and methanol­modified (0.035 mole fraction of methanol) supercritical carbon dioxide at temperatures 318, 328, 338 and 348 K and densities 600, 700 and 800 kg/m3 has been carried out. The solubility of the acids in the supercritical fluids was calculated based on the simulation data by Chrastil’s equation. It is shown that the solubility evaluated using this calculation procedure is quite close to the experimental solubility values known from the literature.


doi: 10.34984/SCFTP.2022.17.4.005

2022, №4

сс. 71-83

Articles

Key words: tandem reactions, aldol-crotonic condensation, hydrogenation, hydride transfer, acetone, isopropanol, supercritical conditions, magnesium stannate catalyst, mesityl oxide, isomesityl oxide

The results of a study of tandem reactions - aldol-crotonic condensation and hydrogenation by the mechanism of hydride transfer in acetone-isopropanol mixtures on a МgSnО3 catalyst at 300-400 °C and 12.0 MРa are presented. In these conditions the mixture ofreactants (acetone and isopropanol) and reaction products is in the supercritical state. The temperature dependences of the reactants conversion and the selectivity for condensation and hydrogenation products are considered. It has been established that the hydrogenation of the acetone aldol-crotonic condensation products proceeds by the addition of hydrogen from isopropanol molecule to the C=O-bonds of isomeric mesityl and phorone oxides and is accompanied by the dehydration of alcohols and the isomeriza­tion of double C=C-bonds. The optimal conditions for the formation of the carbonyl group hydrogenation products are 350°C and the ratio acetone : isopropanol = 7 : 3. At the acetone to isopropanol ratio 1 : 1, methylpentadienes dominate in the products of mesityl oxide conversion.The hydrogenation reaction also proceeds with the participation of isophorones, the condensation products of three acetone molecules.


doi: 10.34984/SCFTP.2022.17.4.006