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Abstract: In this paper, the physicochemical and catalytic properties of SAPO-11 and SAPO-41 molecular sieves granulated with a binder material and promoted with 0.5 wt % Pt have been studied in the isodewaxing of a hydrotreated diesel fraction. It has been shown that the introduction of ~30 wt % of boehmite, which transforms into alumina under calcination, into the granules leads to a decrease in the micropore volume by 50–70% and an increase in the external specific surface area of the material by 6–12% as compared to the highly dispersed samples of the above molecular sieves. It has been found that, at 340°C, 3 MPa, 2.0 h−1, and H2/feedstock = 800 m3/m3, both samples of bifunctional catalysts provide the production of diesel fuel with a pour point of –42°C and a yield of ~91–92 wt %. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700089
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Abstract: Cyclooctene and alkylbenzenes are subjected to co-oxidation in oxygen and a system of two catalysts. Radical catalyst Fe(acac)3/NHPI mediates the formation of alkylbenzene hydroperoxides, which are consumed in situ during the MoO3/SiO2-catalyzed epoxidation of cyclooctene. The chain oxidation rate is limited in cyclooctene and MoO3/SiO2, but radical catalyst Fe(acac)3/NHPI retains fairly high activity in the oxidation of alkylbenzene in hydroperoxide. It is found that isopropylbenzene is a better co-reducing agent than ethylbenzene because it ensures more vigorous and selective formation of epoxycyclooctane. At optimized amounts of components and a temperature of 80°C, selectivity toward epoxycyclooctane reaches 92 and 96% in ethylbenzene or isopropylbenzene, respectively, with more than 70% conversion of cyclooctene. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700041
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Abstract: The authors study the effect of the tungsten oxide in the supports of 0.5% Pt/WOx-Al2O3 catalysts on their acidity, deposited platinum dispersity, and catalytic properties in the hydrodeoxygenation of sunflower oil. It is shown that the of Brønsted acid sites on its surface grows, and the dispersity of deposited platinum in the ready catalyst is reduced when the content of the modifier is increased. The studied samples ensure complete sunflower oil conversion in a hydrogen atmosphere at a liquid weight hourly space velocity (WHSV) of 1 h−1, a temperature of 380°C, and a total pressure of 4 MPa the composition of the support. A nearly stoichiometric yield of C5+ products at a level of 82–86 wt % is attained. The acidic properties of the 0.5% Pt/WOx-Al2O3 system determine the possibility for synthesizing the components of diesels with high contents of iso-alkanes as a result of sunflower oil hydrodeoxygenation. Using a catalyst with a nominal tungsten content of 15 wt % WO3 brings the content of iso-paraffins up to 74% with complete conversion of the initial feedstock for no less than 24 h. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700090
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Abstract: It has been shown that solketal can be synthesized from glycerol and acetone irradiation in the presence of montmorillonite (MM) modified with an aqueous solution of 0.25 mol/L of HCl (0.25M HCl/MM). The reaction has been studied in a methanol solution at an acetone/glycerol molar ratio of 2.45–7.53, a catalyst concentration of 1.2–2.8 wt % (based on glycerol weight), and 30–56°C. It has been shown that solketal is the major product with a selectivity of 96.1–99.2%. The maximum solketal yield of 91.3% with a 98.6% selectivity is obtained within 15 min of reaction at an acetone/glycerol molar ratio of 7.53, a catalyst loading of 2.3 wt % (based on glycerol weight), and 56°C. The catalytic properties of 0.25M HCl/MM in the reaction under microwave and thermal heating conditions have been compared. It has been shown that the solketal yield in the reaction under MW irradiation is 2 times higher than that in the process with thermal heating. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700053
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Abstract: In this work, sorbents based on magnesium oxide MgO modified with NaNO3 taken in a concentration of 5–50 mol % have been synthesized and studied by various methods. It has been shown that the optimum synthesis method is impregnation of the MgO precursor. The optimum concentration of NaNO3 as a modifier is 10 mol %; this concentration provides a sorption capacity of 6.5 mmol CO2/gsorb within 1 h of sorption at 320°C and a CO2 content of 50 vol %. The sorption capacity achieved in 10 consecutive sorption–desorption cycles for 10 mol % NaNO3 is 4.5–5.5 mmol CO2/gsorb within 30 min of sorption at 50 vol % CO2 and temperatures of 300 and 350°C for the sorption and desorption stages, respectively. It has been found that an increase in the total sorption pressure to 10 atm makes it possible to decrease the sorption temperature to 220–260°C, and the achieved sorption capacity is 4.0 mmol CO2/gsorb at 25 vol % CO2, which is almost 2 times higher than the sorption capacity value at 1 atm. It has been shown that treatment with steam and hydrogen does not lead to a significant change in the sorption properties and phase composition of MgO modified with NaNO3. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700016
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Abstract: Novel WO3–ZrO2 (WZ) catalysts with palladium as an active metal on porous alumina supports of various phase compositions have been synthesized. Aluminas from Sasol molded in the form of extrudates (E) and spherical aluminas (S), in which the phase composition is presented by θ-Al2O3, δ-Al2O3, and α-Al2O3 alumina, have been used as supports. It has been shown that the phase composition of the support has a significant effect on the activity of supported Pd/WZ catalysts based on it. Upon transition from a set of θ- and δ-Al2O3 phases to the θ- and α-Al2O3 phase composition has led to an increase in the activity of the catalysts, as evidenced by a shift of 10–30°C in the temperature dependences of the heptane conversion to lower temperatures. The appearance of the α-Al2O3 phase is accompanied by a decrease in the specific surface area of the catalysts, which leads to an increase in the density of acid sites and, as a consequence, a change in activity. The Pd/WZ catalysts supported on S aluminas are characterized by a higher acidity (3.7–6.3 μmol/m2) as compared to the samples supported on E aluminas (2.8–3.6 µmol/m2). The high acidity of the Pd/WZ/S catalysts intensifies the heptane cracking side reactions to form gaseous C1–C4 hydrocarbons. In turn, the moderate acidity of the Pd/WZ/E catalysts contributes to a higher selectivity to heptane isomers (89.2–89.3% at a heptane conversion of 81.5–83.2%) as compared to the catalysts supported on S supports (isomerization selectivity of 84.9–85.6% at a heptane conversion of 80.4–81.4%). PubDate: 2024-06-01 DOI: 10.1134/S207005042470003X
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Abstract: The authors study the effect of the content of zeolite ZSM-22 (15–70 wt %) in a support on the physicochemical properties of Pt/ZSM-22–Al2O3 catalysts. The dependence of the yield and composition of sunflower oil hydrodeoxygenation products on these catalysts on the temperature (310–340°C), pressure (3‒5 MPa), and weight hourly space velocity (WHSV) (0.8–3 h−1) is determined. The possibility is shown of the full hydrodeoxygenation of sunflower oil with the formation of C5+ hydrocarbons containing up to 72% of iso-paraffins with yields of 75–79 wt %. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700065
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Abstract: In this paper, high-loaded copper-containing catalysts synthesized by the different methods (sol–gel, fusion, coprecipitation) have been studied in furfural hydroconversion in a batch reactor at a hydrogen pressure of 5.0 MPa and a temperature of 100°C. The reduction temperatures and phase composition of the catalysts have been determined by physicochemical methods. It has been shown that the highest activity in the studied process is exhibited by a coprecipitated copper–alumina catalyst, which provides the production of furfuryl alcohol with a selectivity of 100% at 100–130°C; in addition, in the presence of this catalyst, 2-methylfuran can be synthesized with a yield of 65% at 200°C. The phase composition of the catalyst reduced at a selected temperature and the catalyst after reaction has been determined. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700028
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Abstract: An essay on the scientific activities of the Russian organic chemist and chemical engineer Sergei Alekseevich Fokin (1865–1917) is presented. The name of the scientist is not widely known although he has made the main contribution to the development of oleochemistry and creation of the industrial process of fat hydrogenation in Russia, and his merits have been appreciated by domestic and foreign researchers. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700107
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Abstract: The authors study the effect of the type of zeolite (SAPO-11, ZSM-22, ZSM-23, and ZSM-12) in a support (ratio zeolite : Al2О3 = 30 : 70) on the physicochemical properties of Pt/Al2O3-zeolite catalysts and the composition of products from the hydrodeoxygenation of sunflower oil on them. The possibility of the complete hydrodeoxygenation of sunflower oil at temperatures of 320–350°C, a pressure of 4 MPa, and a weight hourly space velocity (WHSV) of 1 h−1 is shown with 75–82% yields of liquid products. The fraction of iso-alkanes and the yield of direct hydrodeoxygenation products grow along with the concentration of Brønsted acid sites in a catalyst in the order 1%Pt/Al2O3-ZSM-22 < 1%Pt/Al2O3-ZSM-12 < 1%Pt/Al2O3-ZSM-23 < 1%Pt/Al2O3-SAPO-11. PubDate: 2024-06-01 DOI: 10.1134/S2070050424700077
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Abstract: An adsorbent consisting of a granular NаX zeolite with a hierarchical porous structure and a high degree of crystallinity and phase purity is used for the efficient drying and purification of natural and associated gases from H2S. The possibility of using KZhV, MP KAKh, KCh-2, and KR-2 kaolins produced in Russia as temporary binder materials during its production is studied. It is found that KZhV and MP KAKh kaolins do not require additional treatment to prepare such an adsorbent. KCh-2 and KR-2 kaolins require additional dispersion. PubDate: 2024-03-01 DOI: 10.1134/S2070050424010021
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Abstract: Adapting domestic commercial catalysts for use in such important technological processes as the environmentally friendly production of hydrogen accompanied by СОх and NОх emissions is in demand under import substitution conditions. Ammonia seems to be the most promising Н2 accumulator, due to its high hydrogen density and simple storage and transportation. This work considers the possibility of using the domestic NIAP-03-01, NIAP-07-01, NIAP-06-06 catalysts and Со-Al2O3/SiO2 developed by the authors in the ammonia dissociation reaction. The conversion and hydrogen production capacity grow in the order NIAP-06-06<NIAP-03-01<NIAP-07-01<Со-Al2O3/SiO2. The conversion of ammonia on Со-Al2O3/SiO2 is close to 100% at 550°C and a gas hourly space velocity (GHSV) of 3000 h−1. The effective activation energies of all the catalysts are comparable to the available literature data for the ammonia decomposition reaction to potentially enable their application at moderate temperatures. PubDate: 2024-03-01 DOI: 10.1134/S2070050424010100
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Abstract: Exhaustive enzymatic hydrolysis is performed for semi-bleached sulfate hardwood cellulose (a semi-finished pulp and paper product) at ultra-high concentrations of it in a reaction mixture (up to 300 g/L per dry compound). Russian commercial enzyme preparations are used for hydrolysis. The best seems to be Agroxil Plus, which has high cellulase and endoxylanase activities. A total of 290 g/L of sugars (including 210 g/L of glucose and 30 g/L of xylose) is obtained using Agroxil Plus (20 mg protein/1 g substrate) in combination with an auxiliary β-glucosidase enzyme preparation (2 mg protein/1 g substrate) at an initial semi-bleached cellulose concentration of 300 g/L. The dosage of Agroxil Plus can be halved (10 mg of protein/1 g of substrate with a total concentration of semi-bleached cellulose of 300 g/L) with a high yield of hydrolysis product (270 g/L of sugars, including 200 g/L of glucose and 30 g/L of xylose), due to the fractional addition of a substrate. PubDate: 2024-03-01 DOI: 10.1134/S2070050424010070
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Abstract: Results of studying ethanol conversion to aromatic hydrocarbons (benzene, toluene, xylenes) that are currently available in the scientific literature are discussed and systematized. The features of ethanol conversion in the presence of zeolite catalysts and the mechanism of each individual stage of ethanol conversion to aromatic hydrocarbons are discussed. The effect of the zeolite catalyst composition, the feedstock composition, and ethanol conversion process conditions is demonstrated. The effect of the modifier of a zeolite catalyst on the aromatic hydrocarbon selectivity is shown. This review can be of interest and of use to researchers of zeolite catalyst systems and alcohol conversion processes. PubDate: 2024-03-01 DOI: 10.1134/S2070050424010033
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Abstract: The review addresses the main approaches used in the thermochemical and catalytic conversion of microalgae biomass (hydrothermal liquefaction, gasification, transesterification, pyrolysis) to produce biofuels. The key conditions that determine the reaction product yield using bio-oil production catalysts and approaches to bio-oil refining are discussed. It is shown that the use of bifunctional acid–base catalysts is most relevant for transesterification processes. The gasification and pyrolysis processes are used less frequently, because the former is accompanied by the formation of CO2, and the latter is characterized by the formation of a large amount of oxidized compounds that deteriorate the quality of bio-oil. PubDate: 2024-03-01 DOI: 10.1134/S2070050424010082
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Abstract: The aim of this review is to summarize and comparatively analyze recent reports on studying carbon dioxide conversion to methanol, dimethyl ether, and C2+ hydrocarbons, in particular, olefins, by catalytic hydrogenation. It is shown that the main approaches to providing high activity and selectivity of these processes are the targeted design of catalysts and the selection of conditions for hydrogenation processes, in particular, the use of supercritical CO2 and procedures that are alternative to conventional physicochemical methods for CO2 activation (electrocatalysis, photocatalysis). PubDate: 2024-03-01 DOI: 10.1134/S2070050424010045
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Abstract: Under slurry reactor conditions, the products of condensation are generrally formed on strong Mg/HZSM-5 acid sites independently of the SiO2/Al2O3 molar ratio in the zeolite. The composition of condensation products remains virtually unchanged as the molar ratio grows and basically consists of trimethyl and tetramethyl benzenes, but their content falls as the volume of mesopores grows with increasing SiO2/Al2O3. This lowers the hindrances to diffusion and the contribution from secondary reactions to improve the removal of coke precursors from the zeolite’s surface and favorably affect the catalyst’s activity (DME conversion doubles). The composition of reaction products changes slightly with an increase in the SiO2/Al2O3 molar ratio, and the total selectivity toward lower olefins is ~70 wt %. A rapid loss in Mg/HZSM-5 activity upon extending the period of operation under slurry reactor conditions is not due to coking, but to the catalyst being clogged by dispersion medium (polydimethylsiloxane) decomposition products. PubDate: 2024-03-01 DOI: 10.1134/S2070050424010094
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Abstract: The paper provides a review of reports in the field of microalgae biomass conversion to various types of biofuels (fatty acid methyl esters, ethanol, butanol, hydrogen) and marketable chemicals, in particular, polyunsaturated fatty acids, pigments, and proteins, using modern chemical and biotechnological approaches. This review addresses the synthesis of products using various strategies applied to develop modern approaches to the integrated biorefinery of microalgae biomass. PubDate: 2024-03-01 DOI: 10.1134/S2070050424010057
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Abstract: The paper provides a review of reports on the results of studies in the field of microalgae biomass cultivation and conversion to marketable chemicals using modern bioengineering approaches. The review discusses approaches to producing biofuels (biodiesel, ethanol, hydrogen) from microalgae. Data on biomass pretreatment methods and various procedures for isolating metabolites and converting them to biofuels are provided. PubDate: 2024-03-01 DOI: 10.1134/S2070050424010069
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Abstract: This study concerns the effect of water-soluble polymers with different structures on the sorption properties of unregenerable lime-based sorbents of carbon dioxide. It is shown that introducing water-soluble polymers into the composition of sorbents can either prolong or shorten the periods of their protective effect. To explain these findings, the porous structure of sorbents is studied, the transport of carbon dioxide is modeled using molecular dynamics, and coefficients of the diffusion of СО2 in water–polymer solutions are calculated. Modelling results correlate with data from sorption experiments: a stronger dynamic sorption capacity is obtained for a sorbent when a water–polymer medium with a greater coefficient of СО2 diffusion is added. These results can be used to optimize systems for separating carbon dioxide from gaseous mixtures and intensify mass transfer in systems for the photo- and electrocatalytic conversion of СО2 into useful products. PubDate: 2023-12-01 DOI: 10.1134/S2070050423040062
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