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Abstract: The effect of iron and manganese additives on the textural characteristics and phase composition of the alumina matrix support was studied for sulfated zirconia catalysts of hexane isomerization. The additives introduced at the stage of plastification of aluminum hydroxide significantly improved the catalyst activity (hexane conversion and selectivity of isomerization to hexane isomers). A distinction of the modified catalysts is the formation of acid sites in a ratio of LAS : BAS ≥ 2, which increase the yield of isomers and especially of high-octane 2,2-dimethylbutane. PubDate: 2021-10-01
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Abstract: A report is given on the recent advances in the design, synthesis, and development of a new catalytic microreactor for the selective and continuous synthesis of value-added substances used in fine organic synthesis and pharmaceutical industry. Inside this advanced reactor, metal nanoparticles are incorporated into mesoporous materials that are deposited as very active and selective catalytic films on the walls of capillary microchannels with diameters of 220 and 530 µm. These microreactor systems require no subsequent separation of the catalyst, which allows their continuous operation. Crystalline and amorphous metal oxides based on titanium dioxide synthesized using the sol gel technique and containing catalytically active polymetallic nanoparticles are potentially the most stable coatings. The catalytic properties and operational stability of capillary microreactors are studied at atmospheric pressure and compared to those of conventional industrial batch reactors. Our Pd50Zn50/TiO2 coating displays higher activity (1.5 gMBE/(gPd s)) and selectivity (96.7%) than coatings described earlier, and retains high catalytic performance after 88 h of a reaction with Lindlar’s industrial catalyst. PubDate: 2021-10-01
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Abstract: Oxygenated products from selective hydrocarbon oxidation have high commercial value as industrial feedstocks. One of the most important industrial processes is the cyclohexane oxidation to produce cyclohexanol and cyclohexanone. These organic substances have special importance in the Nylon manufacture as well as building blocks for a variety of commercially useful products. In this work we present the synthesis and characterization of a new mononuclear piperazine-derived series of iron(III) complexes and their catalytic activity towards cyclohexane oxidation essays. All complexes present octahedral high-spin iron(III) center according to elemental analysis, FTIR, UV-VIS and Mössbauer spectroscopy characterization. The cyclohexane oxidation resulted in cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide as products, with yields up to 39%. The best results were obtained with the complex (NH4)[Fe(BPPZ)Cl2] (BPPZ: lithium 1,4-bis(propanoate)piperazine) and with hydrogen peroxide as oxidant. The reactions were carried out at room temperature and atmospheric pressure, which incomes a great advantage over the current industrial process of cyclohexane production. PubDate: 2021-10-01
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Abstract: Polyfunctional Ni- and Mo-containing catalysts are prepared by sequentially impregnating a support (SiO2, Al2O3, B2O3–Al2O3, \({\text{SO}}_{4}^{{2 - }}\) /Al2O3, \({\text{SO}}_{4}^{{2 - }}\) /ZrO2) using solutions of corresponding salts with intermediate steps of drying at 120°C and calcination at 500–550°C. X-ray powder diffraction, temperature programmed reduction, UV-VIS diffuse reflectance spectroscopy, and electron spin resonance spectroscopy are used to study physicochemical properties of the prepared catalysts. The catalysts are tested in the direct synthesis of propylene from ethylene at an atmospheric pressure, 200°C and an ethylene weight hourly space velocity of 0.5 h−1. The highest conversion of ethylene and yield of propylene are achieved for a sample based on borated alumina, due to the formation of active sites of ethylene dimerization, Ni2+ ions bound to acid sites of the support, and active sites of metathesis (surface monomolybdate compounds). PubDate: 2021-10-01
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Abstract: The effect of fluorine addition to the alumina matrix used for the preparation of supported sulfated zirconia catalysts has been studied. The fluorinating agent was hydrofluoric acid. Fluorine additions affect the textural characteristics of the Al2O3 matrix and, as a consequence, the surface area of sulfated zirconia catalysts based on modified systems. The introduction of fluorine in the catalyst composition to an increase in the activity (conversion of hexane) and yield of the high-octane isomer 2,2-dimethylbutane. PubDate: 2021-10-01
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Abstract: Hydrogenation of CO2 to CO and hydrocarbons is carried out over a wide range of catalysts. Group of VIIIB transition metals have proved high conversion and selectively for CO and methane. Meanwhile, low cost and effective catalysts are preferable in an industrial scale. In this work, the synergistic effect of iron content on the catalytic performance were investigated in carbon dioxide hydrogenation reaction. Incipient wetness impregnation procedure was used for the preparation of four γ-Al2O3 supported iron-based catalysts. BET, XRD, H2-TPR and TEM techniques were employed for the catalyst characterization. The evaluation of catalysts were carried out in a fixed bed reactor at the process conditions of temperature of 300°C, pressure of 20 atm, H2 to CO2 ratio of 3 and GHSV of 3 NL/(h gCat). It was found that the promoter addition improves the activity of Fe catalyst for both Fischer-Tropsch synthesis (FTS) and Reverse Water Gas Shift (RWGS) reactions. The results showed that conversion of CO2 was from 15.6 to 35.6% with major products of methane, C2 to C4, C5+ and CO. It was also found that impact of K and Ce promoters into iron catalyst showed the highest conversion and hydrocarbon yield due to the synergistic effect. PubDate: 2021-10-01
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Abstract: The oligomerization of ethylene in aliphatic and aromatic solvents on complex zirconium carboxylate catalytic systems obtained from naphthenic acid fractions isolated from Baku oils is studied for the first time. Comparative studies are performed using complex zirconium carboxylate catalytic systems obtained from individual carboxylic acids CH3(CH2)2COOH and CH3(CH2)8COOH. It is found that the activity of a catalyst and the molecular weight distribution (MWD) of oligomeric products depend mainly on the solvent and the composition of the zirconium complex. It is shown that the rate of ethylene oligomerization when using zirconium carboxylate catalytic systems in aliphatic solvents is 2–3 times lower than in aromatic solvents. The resulting product has a narrow MWD and consists mainly of C4–C10 fractions. The oligomeric products obtained in aromatic solvents have wide MWDs and consist mainly of C4–C18 in the presence of zirconium carboxylates and of C12–C18 and C20 fractions with zirconium naphthenates. PubDate: 2021-10-01
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Abstract: The second part of a series of reviews on the direct synthesis of organotin compounds is presented. In this part, the conditions and results of the reaction between metallic tin and allkyl halides are considered. The efficiency of application is analyzed for different catalysts along side with their systematization, and some possible mechanisms of these processes are discussed. PubDate: 2021-10-01
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Abstract: The effect of the tungsten oxide content (10–35 wt %) in Pt/WO3-ZrO2 catalysts on hydroisomerization of a heptane–benzene mixture (80 : 20, wt %) has been studied. The catalysts with 15–25 wt % WO3 are characterized by the highest fraction of the tetragonal phase of zirconia (t-ZrO2, 87–96%), which makes it possible to achieve the highest yield of the sum of heptane isomers, including high-octane di- and trimethyl-substituted isomers (DTMS; 69.4–76.7 and 24.5–27.9 wt %, respectively). In the presence of these catalysts, the yield of methylcyclopentane is 52.1–61.3 wt % at 72.6–90.9% selectivity of isomerization of cyclohexane to methylcyclopentane. PubDate: 2021-10-01
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Abstract: The effect of 0.3 wt % of indium introduced at the peptization and aluminum oxide impregnation stages on the properties of alumina-platinum reforming catalysts has been studied. Modification with indium at the impregnation stage reduces the total acidity of the support to a lesser extent and, as a consequence, the conversion of heptane for the corresponding Pt/In/Al2O3-Cl catalyst. This sample demonstrates the greatest decrease in the selectivity of the hydrogenolysis and hydrocracking reaction alongside with a maximum ratio of i-C5–7/toluene selectivities as compared to the catalysis doped with In at the peptization stage and without doping. PubDate: 2021-10-01
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Abstract: A study is performed for the aldol condensation of formaldehyde with dihydroxyacetone (DHA) in an aqueous medium (pH 7.54–8.71) at 65–80°C using zinc zeolitic imidazolate frameworks based on 2-methylimidazole (ZIF-8) and 2-ethylimidazole (MAF-5 and MAF-6). It is shown that the selectivity of the process depends on the pH of the reaction solution, which is controlled by the temperature of the reaction and the amount of catalyst in the reaction mixture. There are high yields of C6 sugars when the reaction is conducted at pH 8.36 and 80°C. The sugars are accompanied by high yields of erythrulose (39–60%) at a temperature of 65°C and. It is found that the yield of erythrulose when using the studied catalytic systems depends on the pore radius and grows in the order MAF-6 > MAF-5 > ZIF-8. The advantages of the studied systems are compared to those of homogeneous and heterogeneous phosphate systems proposed in the literature. PubDate: 2021-10-01
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Abstract: A study is performed of the effect of additives of quadruply charged ions on the composition, chemical stability, and catalytic properties of samples of potassium polyferrites with a β″-alumina type structure of \({{{\text{K}}}_{{\text{2}}}}{\text{Fe}}_{{{\text{1 + }}q}}^{{{\text{II}}}}{\text{Fe}}_{{{\text{10}} - {\text{2}}q}}^{{{\text{III}}}}{\text{Me}}_{q}^{{{\text{IV}}}}{{{\text{O}}}_{{{\text{17}}}}}\) , where Me is Ce, Ti, or Zr, and q = 0–1.0. The mechanism is determined for the effect produced by the additives of quadruply charged cations on the activity, selectivity, and corrosion resistance of β″-potassium polyferrite is determined. Polyferrites doped with quadruply charged cations are characterized by a drop in the specific rate of styrene formation and an increase in ethyl benzene dehydrogenation selectivity. The destabilizing effect of titanium additives is revealed. It is expressed in facilitating the emission of an alkali metal from the crystal lattice of polyferrite. Cerium additives result in the destruction of the polyferrite structure due to the reduction of Ce4+→ Be3+ for values of parameter q greater than 0.6. Zirconium additives do not reduce the corrosion resistance of ferrite systems under the conditions of dehydrogenation. PubDate: 2021-10-01
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Abstract: The conversion of methane–ethane, methane–ethylene, hydrogen–ethane, and hydrogen–ethylene mixtures on an electrically heated resistive fechral catalyst is studied. In the course of conversion, the catalyst surface is covered with graphite-like carbon deposits that have an additional catalytic effect resulting in the formation of C3 and C4 hydrocarbons. The latter are apparently formed with participation of ethylene formed from ethane. Hydrogen suppresses coking on the catalyst’s surface and reduces the yield of C3 and C4 hydrocarbons. PubDate: 2021-07-01 DOI: 10.1134/S2070050421030090
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Abstract: A study on the synthesis of nitrous oxide via the selective oxidation of ammonia in a microreactor in the form of a metallic disk with cylindrical channels filled with a manganese–bismuth oxide catalyst has been. A 3D mathematical model is presented for this microreactor that considers the transfer of mass and axial and radial heat, the catalytic reactions, the change they produce in the volume of the reaction mixture, the transfer of heat between the disk and the channels, and the heat conductivity of the disk. Parameters are determined that ensure the maximum nitrous oxide production with allowance for the limitations of temperature in the microreactor channels. The highest efficiency of nitrous oxide production is attained at an outer reactor edge temperature of 370°C and an inlet ammonia concentration of 20 vol %. The production capacity per unit catalyst volume in the microreactor is nearly 1.5 times higher than in a tubular reactor, and the maximum temperature corresponds to the level that provides the best process selectivity toward nitrous oxide. PubDate: 2021-07-01 DOI: 10.1134/S2070050421030065
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Abstract: The catalytic hydrogenation of a carbon–carbon triple bond in acetylene compounds is an important industrial process in which high selectivity toward olefin compounds must be ensured. This work considers the effect of treating palladium catalysts based on hyper-cross-linked polystyrene (HPS) with sodium carbonate on the activity and selectivity in the hydrogenation of 2-methyl-3-butyn-2-ol and phenylacetylene is considered. The effect of such treatment depends on the palladium precursor and the polymer support (HPS non-functionalized or HPS containing tertiary amino groups). Selectivity in the hydrogenation of 2-methyl-3-butyn-2-ol (95% conversion of the substrate) is 98% at ambient hydrogen pressure and 90°C in toluene for 1%-Pd/HPS catalysts treated with Na2CO3 and 99.5% in the hydrogenation of phenylacetylene. PubDate: 2021-07-01 DOI: 10.1134/S2070050421030028
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Abstract: This review is the first part of a series of reviews devoted to the direct synthesis of organotin compounds. The conditions for and results from the reaction between tin alloys and organohalides are considered. The efficiency of catalysts and the prospects for using tin alloys in the synthesis of organotin compounds are analyzed, and some possible mechanisms of these processes are discussed. PubDate: 2021-07-01 DOI: 10.1134/S2070050421030107
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Abstract: The deep oxidation of hydrocarbons on platinum catalysts underlies most processes for cleaning gas emissions from industrial enterprises. Since carbon monoxide is usually present in exhaust gases, it is important to study its effect on the kinetics of hydrocarbon oxidation. This work presents results from studying the kinetics of propane oxidation on a platinum glass fiber catalyst with and without CO in the reaction mixture. It is found that CO strongly inhibits the oxidation of propane at low temperatures. The effect of CO changes from negative to positive as the temperature rises. Numerical modeling shows the multidirectionality of the effect can be explained by competition between the adsorption of oxygen, propane, and CO on the active sites of the catalyst. PubDate: 2021-07-01 DOI: 10.1134/S2070050421030077
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Abstract: γ-Valerolactone (GVL) is a valuable chemical compound known as a platform molecule. It is considered as an intermediate product for the synthesis of chemical compounds with high added value, components of motor fuels, and biopolymers. GVL is well established as an environmentally safe solvent, fuel additive, flavoring, and nutritional supplement. This review summarizes the latest advances in the development of catalytic ways of GVL synthesis from levulinic acid (LA), alkyl levulinates (ALs), and carbohydrates and plant polymers. Special attention is given to heterogeneous catalysts based on metals and metal oxides, which are more promising for practical application. Proposed mechanisms of the processes are considered in detail, and the prospect of using hydrogen-donor solvents in the processes of GVL production is discussed. Catalysts demonstrating the best catalytic properties are compared from the viewpoint of their productivity, an important parameter for industrial catalysis. PubDate: 2021-07-01 DOI: 10.1134/S2070050421030119
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Abstract: It is important today to find ways for the synthesis of hydrogen such as to avoid emissions of carbon oxides into the atmosphere and ensure the use of so-called low-carbon energy. Producing hydrogen through the thermocatalytic methane decomposition (CMD) on carbon catalysts yields not only a valuable, environmentally friendly fuel in the form of hydrogen, but also a wide range of carbon materials that can be used in a number of industries. The use of carbon catalysts is essential for the economic efficiency of methane decomposition. This paper describes the CMD fundamentals and summarizes results from studying the catalytic activity in this process for carbon materials (activated carbon, carbon black, nanotubes, nanofibers) that differ in structure and physical and chemical properties. The main problems and prospects of using this technology are identified. PubDate: 2021-07-01 DOI: 10.1134/S2070050421030089
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Abstract: Some specific features in the liquid-phase oxidation of alkenes to ketones or aldehydes in the presence of palladium compounds (Wacker oxidation) are discussed. It is shown that selecting the appropriate conditions of the reaction (the effective compositions of the catalyst, the oxidizing agent, and solvent) allows the selective synthesis of either ketones or aldehydes from terminal alkenes and ketones from internal alkenes. PubDate: 2021-07-01 DOI: 10.1134/S2070050421030041
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