Abstract: Results are presented from a comparative study of CO2 hydrogenation under gas-phase and supercritical conditions for CO2 in the presence of 15% Fe/SiO2 catalyst. The reaction is studied in the temperature range of 300–500°C at atmospheric pressure under gas-phase conditions and at a pressure of 95 atm under supercritical conditions at an Н2 : СО2 molar ratio of 2 : 1. It is found that the process proceeding under supercritical conditions lowers CO selectivity from 90–95 to 30–50% over the range of temperatures and raises (up to 60%) the hydrocarbon selectivity. In contrast to gas-phase hydrogenation, the formation of alcohols is observed in the reaction under supercritical conditions. Using a combination of thermogravimetry, differential thermogravimetry, and differential thermal analysis (TG–DTG–DTA), it is shown that the process proceeding under supercritical conditions results in a 2.2-fold drop in the amount of carbon-like deposits on the catalyst surface. X-ray diffraction analysis shows that under gas-phase process conditions, graphite-like structures form on the catalyst surface; this effect is not observed under supercritical conditions. The developed catalyst and the process for CO2 hydrogenation can be recommended for the further modification and improvement of the properties of a catalyst based on iron nanoparticles that is much (10–100 times) cheaper than the previously reported CO2 hydrogenation catalysts. PubDate: 2018-10-01
Abstract: The physicochemical state of supported platinum and the surface of the support is studied for a number of industrial 0.5 wt % Pt/graphite (freshly prepared, after the synthesis of hydroxylamine sulfate via NO hydrogenation in sulfuric acid, and regenerated) by scanning electron microscopy (SEM), transmission electron microscopy(TEM), X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and CO chemisorption. It is shown that platinum particles agglomerate in a catalyst during operation, and its regeneration results in finer dispersity of the supported metal. Despite the common opinion that a platinum surface is modified by sulfur during the synthesis or regeneration of such catalysts, no evidence of this is found via XPS. Data showing that the surface nitrogen-containing graphite groups formed during the preparation of a catalyst are responsible for the modification of the absorption properties of platinum particles with respect to CO are obtained for the first time. The latter seems to be one of the factors that influence the catalytic properties of platinum in NO hydrogenation. PubDate: 2018-10-01
Abstract: The catalytic properties of Amberlyst A-21 anion-exchange resin in the gas-phase disproportionation reaction of trichlorosilane (TCS) at temperatures (up to 423 K) critical for the resin are investigated for the first time. It is established using thermal desorprtion followed by pyrolysis that Amberlyst A-21 undergoes thermal destruction to form chloromethane and the spherical polymer matrix decomposes at above 423 K. In the temperature range of 333–423 K, the apparent activation energy of disproportionation of TCS with using Amberlyst A-21 is 37.12 kJ/mol and the reaction rate constant is 0.80 s−1 (at 423 K). Three months of testing of the resin in disproportionation of TCS at 423 K demonstrates its stable catalytic activity. PubDate: 2018-10-01
Abstract: Results are presented from studying the steam cracking of heavy oil at a temperature of 425°C and a pressure of 2.0 MPa over dispersed iron and molybdenum based catalysts in a slurry reactor. The catalysts are synthesized through the decomposition of water-soluble precursors of metal salts in situ. The yield of upgraded oil (the sum of liquid products) is found to grow with steam cracking, in comparison to thermal cracking (80 and 77%, respectively). The use of dispersed monometallic (iron- or molybdenum-containing) catalysts and a bimetallic catalyst for the catalytic steam cracking (CSC) of heavy oil increases the yield of SOPs. In addition, the yield of light fractions (Тb < 350°C) in the CSC process is found to grow in comparison to steam and thermal cracking, and the viscosity and density of products falls, relative to the initial feedstock. PubDate: 2018-10-01
Abstract: The catalytic properties of the industrial “palladium on sibunit” catalyst (ICT-3-31, 0.5 wt % Pd) were studied in the reduction of menthone into menthol. Menthone was reduced both at 250 and 350°C using isopropanol as an H-donor under the conditions of the hydrogen transfer reaction (HTR). For comparison, a noncatalytic reaction was performed under the same conditions. At 350°C the conversion of menthone was the same (61–62%) in the presence of the catalyst and without it. In the reaction with the catalyst, the selectivity on the desired product menthol decreased considerably (from 98% down to 23%), and the amount of the by-products increased (from 2 up to 77% based on changed menthone). When the temperature of the catalytic reaction was lowered to 250°C, the reduction selectivity increased to 42%, but the conversion of menthone decreased to 10%. All the products of menthone conversion were identified and pathways of their formation suggested. At 250–350°C the carbon support sibunit catalyzed the dehydration of menthone, which hindered the satisfactory yields of the target alcohol. Other side reactions catalyzed by ICT-3-31 were dehydrogenation into p-menthenes and their further aromatization resulted in the formation of substituted benzenes—p-cymene and thymol. ICT-3-31 can be effectively used in HTR, if more reactive organic substrates are involved in the reaction below 200–250°C or stronger H-donors are applied. PubDate: 2018-10-01
Abstract: It is shown that copolymers of polyethylene- and polypropyleneglycolmaleates (p-EGM and p‑PGM) with acrylic acid (AA) can be used as matrices for the preparation of effective metal-polymer complexes for hydrogenation of organic compounds. Electron microscope and dynamic scattering are used to determine the average nanoparticle size of 112 nm; the nanoparticles are spheres with a uniform distribution along the polymer’s cross section. The contents of nickel and cobalt in p-EGM/AA are 0.52 and 0.48 wt %, respectively, and 0.49 and 0.51 wt % in p-PGM/AA, respectively. It is found that raising the temperature from 25 to 40°C allows the rate of pyridine hydrogenation to be increased substantially as a result of catalyst activation and an increase in the number of catalyst active centers, due to the swelling of the polymer network and its transition from the tight globular to the expanded state. Raising the current’s strength from 1 to 3 A lowers the yield of piperidine, which does not allow the increase in the current density to be used to shorten the length of synthesis. It may be concluded that the experimental data allow a final product of hydrogenation with higher rates and yields to be obtained. PubDate: 2018-10-01
Abstract: The oxidation of diesel fuel was studied using the vibrofluidized and fluidized beds of disperse river sand in the presence of iron-containing microspheres isolated from the fly ash of coal boiler stations: ferrospheres and cenospheres activated with iron oxide. The results were compared with the available data on the oxidation of diesel fuel using the microspheres of commercial catalysts for complete oxidation of organic compounds. In the presence of ferrospheres and cenospheres with deposited iron oxide at 500–600°C, deeper oxidation of diesel fuel was observed than in the vibrofluidized bed of an inert material (river sand). The most complete oxidation (84.3%) was observed with ferrospheres at 700°C. The ferrospheres used in the oxidation of diesel fuel in the fluidized bed of the inert material showed lower activity under these conditions than the commercial catalysts based on СuСr2О4/А12О3 and disperse Fe2O3. Nevertheless, higher oxidation rate, 97.8%, can be achieved in the presence of ferrospheres by arranging flare combustion of diesel fuel above the bed. In this case, the flame length decreases by half compared with that above the bed of the inert material. This, as well as the decreased CO content and unburnt carbon in combustion products, indicate the catalytic activity of ferrospheres fed to the flame. PubDate: 2018-10-01
Abstract: The conventional way of producing microcrystalline cellulose (MCC) from wood raw materials is multistage; it is based on integrating the environmentally hazardous processes of pulping and bleaching of cellulose and the acid hydrolysis of the amorphous phase of cellulose. This work describes an improved single-stage catalytic method for the production of MCC from softwood and hardwood that is based on the peroxide delignification of wood in an acetic acid–water medium under mild conditions (100°C, atmospheric pressure) in the presence of an environmentally safe TiO2 solid catalyst. The processes of MCC production via the peroxide catalytic delignification of various wood species are optimized experimentally and mathematically. The following optimum modes for the production of MCC with a yield of 36.3–42.0 wt % of absolutely dry wood, a residual lignin content of ≤1.0 wt %, and a hemicellulose content of ≤ 6.0 wt % are determined: For aspen: 5 wt % H2O2, 25 wt % CH3COOH, and a liquid/wood ratio of 10. For birch: 5 wt % H2O2, 25 wt % CH3COOH, and a liquid/wood ratio of 15. For silver fir: 6 wt % H2O2, 30 wt % CH3COOH, and a liquid/wood ratio of 15. For larch: 6 wt % H2O2, 30 wt % CH3COOH, and a liquid/wood ratio of 15. PubDate: 2018-10-01
Abstract: The possibility of using arctic low-sulfur diesel fuel for the production of syngas suitable for solid-oxide fuel cells (SOFSs) in a single stage via the prereforming reaction over Ni-MgO structured catalysts based on a highly porous cellular foam material (HPCFM) made of nickel is demonstrated. Catalysts with mass compositions (wt %) 10.7NiO–10MgO/HPCFM and 20NiO–10MgO/HPCFM are prepared, and their properties in the prereforming of arctic diesel fuel at 550°C are studied. The microstructure of the coating of these catalysts is studied via transmission electron microscopy (TEM) before and after the reaction. The resistance of these prereforming catalysts to carbonization is revealed to be the key factor influencing their stability under operation. The kinetic parameters of this reaction are determined. The obtained results could be helpful in creating power generation units based on fuel cells operating on arctic diesel fuel under the conditions of the Far North. PubDate: 2018-10-01
Abstract: The possibility of preparing a mixture of 1,3-dialkylimidazole salts from commercially available reagents via multicomponent condensation is considered. The main factors affecting the yield of the target product, and the experimental data needed for scaling up the process, are discussed. It is shown that the prepared mixtures are close in some key properties (e.g., viscosity at different temperatures, heat capacity) to the pure salts. The possibility of using the prepared salts as solvents for catalytic hydrodechlorination and catalyst components for the alkylation of aromatic compounds is demonstrated. PubDate: 2018-10-01
Abstract: The catalytic hydrogenation of nitrobenzene (NB) is an important technological stage in the production of aniline (AN). The catalytic behavior of hypercrosslinked polystyrene based ruthenium catalyst 3%Ru/MN270 in the three-phase hydrogenation of NB to AN is considered in this work. The following parameters are varied: 0.12 to 0.24 mol/L of NB; 1.11 × 10−4 to 11.12 × 10−4 mol/L of catalyst; temperatures of 160 to 190°C; and partial hydrogen pressures of 0.113 to 1.013 MPa. The optimum process parameters are determined to ensure 98% selectivity toward aniline with 97% conversion of nitrobenzene. PubDate: 2018-10-01
Abstract: RuO2 particles stabilized in a polymeric matrix of hypercrosslinked polystyrene of MN100 type (5% Ru/MN100) are characterized by physicochemical methods (low-temperature nitrogen adsorption, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy), and the catalytic activity of these particles is studied in the reaction of selective hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). It is shown that synthesized catalyst 5% Ru/MN100 ensures a GVL yield above 99% under mild reaction conditions (90°C; hydrogen partial pressure, 2 MPa) in an aqueous medium and can compete with commercial catalyst 5% Ru/C. PubDate: 2018-10-01
Abstract: The composition and properties of a wide variety of domestic and foreign enzyme preparations (EP) used as additives to feeds of farm animals and poultry are analyzed. Content of the main active enzymes – endoglucanases (beta-glucanases), cellobiohydrolases, and xylanases performing biocatalytic destruction of non-starch polysaccharides, which are anti-nutritional factors in feeds causing their incomplete digestion, is determined. It is shown that based on the component composition data and the level of different types of activity the studied enzyme preparations can be classified into three groups: a) with high xylanase and low cellulase (endoglucanase and cellobiohydrolase) content, b) with high cellulase and low xylanase content, c) containing cellobiohydrolases, endoglucanases and xylanases at a different ratio, but without significant prevalence of any of these enzymes. The ability of EP to reduce the viscosity of water-soluble non-starch polysaccharides – xylans and beta-glucans – has been studied. Among the enzyme preparations that have xylanase in their composition and belong to the groups b) and c) a number of preparations have been identified (Econase XT 25, Agroxyl Plus, Agroxyl Premium, Rovabio Max AP, Sunzyme), which reduced the viscosity of aqueous extract of rye containing xylans most effectively when used at the same dosage with regards to xylanase activity. It was shown that xylanase from precisely these EP was not inhibited by the protein inhibitors of rye. The viscosity of water-soluble beta-glucans of barley was most effectively reduced by the EP Xybeten CELL, Cellulase, Agroxyl, Agrocel, Axtra XB 201, Rovabio Max AP, and Vilzim used at the same dosage with regards to beta-glucanase activity. For all the studied EP, no inhibitory effect of the barley extract on beta-glucanase activity was found. PubDate: 2018-10-01
Abstract: The effect modifying the HZSM-5 zeolite contained in a bizeolite catalyst has on the conversion of hydrotreated vacuum gas oil, vegetable oil, and a vacuum gas oil–vegetable oil mixture under conditions of catalytic cracking is investigated. It is found that modification lowers both the specific surface area and the volume of the meso- and micropores of HZSM-5 zeolite; the higher the phosphorus content, the greater the reduction in the main characteristics of the pore structure of the zeolite. A drop in the total acidity of P/HZSM-5 and a quantitative redistribution of weak and medium-strength acid sites are also observed. Catalytic tests of the zeolites in the cracking process show that phosphorus modification helps increase the total yield of propane–propylene and butane–butylene fractions with high olefin contents. Alkaline treatment of HZSM-5 zeolite with a high SiO2/Al2O3 ratio facilitates the extraction of silicon and increases the specific surface area of mesopores considerably. In addition, weakening of the strong acid sites of the zeolite and/or a change in the accessibility of these sites due to the partial removal of silicon is observed. PubDate: 2018-10-01
Abstract: The modification effect of NiCu–SiO2 catalysts by molybdenum on their activity and selectivity in the hydrogenation of furfural—a product of the acid hydrolysis of hemicellulose biomass—was studied. The original NiCu catalyst was synthesized by the sol–gel method and stabilized with 10 wt % SiO2 by impregnating the calcined sol–gel with an appropriate amount of ethyl silicate. Molybdenum was introduced by impregnation of the original catalyst with an aqueous solution of ammonium molybdate. The selective hydrogenation of furfural was carried out in a batch reactor at temperatures of 100–200°C and a hydrogen pressure of 6 MPa. It was shown that an increase in the process temperature in the presence of the molybdenum-containing catalyst increases the yield of 2-methylfuran and products of complete hydrogenation. At low process temperatures a small amount of 2-methylfuran is formed; the main products are furfuryl and tetrahydrofurfuryl alcohols. The modified NiCuMo–SiO2 catalysts exhibit higher activity in hydrogenation of furfural and greater 2-methylfuran selectivity than the respective parameters of NiCu systems, due apparently to the formation of NiMo(Cu) solid solutions, and the formation of Mox+ on the catalyst surface. PubDate: 2018-07-01
Abstract: A new Ru-containing catalyst based on Fe3O4–SiO2 particles that exhibit magnetic properties is proposed for the hydrogenolysis of cellulose to glycols and the hydrolytic hydrogenation of inulin to mannitol. The effect of process parameters on the selectivity toward the main products is studied. Under optimum conditions of cellulose hydrogenolysis, the total glycol selectivity is ≈40% (ethylene glycol, 19.1%; propylene glycol, 20.9%) at 100% cellulose conversion. In the hydrolytic hydrogenation of inulin, the maximum mannitol selectivity is 44.3% at a 100% conversion of the feed polysaccharide. The proposed catalyst is stable under hydrothermal process conditions, and can be easily separated from the reaction mass using an external magnetic field. PubDate: 2018-07-01
Abstract: Modern approaches to the utilization of hydrocarbon gases are analyzed. Such gases are a byproduct from the production of oil, shale oil, and rich natural gas, and are most often subjected to flare combustion at production fields. PubDate: 2018-07-01
Abstract: — More than 70% of the world’s reserves of hydrocarbons is in the form of heavy petroleum feedstocks. Increasing the efficiency and depth of processing of such feedstocks is an important problem of petroleum refining. Cobalt powders and their catalysts prepared in a single stage are tested for the first time in the cracking process at the Novokuibyshevsk petroleum refinery. The composition and properties of the samples are studied via X-ray phase analysis, scanning electron microscopy, and temperature-programmed reduction. Surfaces of cobalt contains oxygen in Co3O4 and CoO inside layers, while mechanoactivation redistributes some of these oxides and alters the composition of products of tar cracking. Cobalt has more catalytic activity in the cracking of tar after mechanoactivation than the original powder. The yield of light fractions is 70% with mechanically activated cobalt, 10 wt % higher than without mechanoactivation, and 25% higher than with no cobalt powders. PubDate: 2018-07-01
Abstract: The properties of iron subgroup metals (Fe, Co, Ni) on a mesoporous carbon Sibunite support during the formation of carbon in the catalytic pyrolysis of high-molecular alkanes (hexane, undecane, and hexadecane) were studied. In the case of the NiO/Sibunite catalyst, the rate of carbon formation at temperatures of 500–600оС decreased in the series hexane > undecane > hexadecane. Carbon is deposited in the form of carbon nanofibers. The activity series of reduced catalysts in carbon formation was determined: 10%NiО/Sibunite > 10%CoО/Sibunite > 10%Fe2О3/Sibunite. The morphology of carbon that formed on the 10%CoО/Sibunite catalyst depends on the particle size of the active component: multiwalled carbon nanotubes (MCNTs) grow on particles of 10–30 nm, and carbon nanofibers grow on particles larger than 30 nm. The X-ray diffraction studies of Fe2O3/Sibunite after the reaction showed that the active component can be in the form of metal or iron carbide, the fraction of each phase in the catalyst depending on the particle size of the active phase. For particles of 10–30 nm, iron is in the form of metal, for larger particles, it is in the form of carbide. It was concluded that iron carbide particles are responsible for the formation of carbon nanofibers, and iron particles are responsible for the formation of MCNTs. PubDate: 2018-07-01
Abstract: The optimum composition is determined for a nutrient medium corresponding to the maximum yield of bioethanol during the alcohol fermentation of the enzymatic hydrolyzate of lignocellulosic material, produced by treating oat hulls with a diluted solution of nitric acid in trial production. The biotechnological steps of saccharification and fermentation are performed using commercially available enzymatic preparations CelloLux-A and BrewZyme BGX, plus a strain of Saccharomyces сerevisiae Y-1693 (VKPM) that is resistant to inhibitors from hydrolyzates. The composition of a nutrient medium that produced a bioethanol yield which was 89.9% of the theoretical one (8.4% higher than the native hydrolyzate) is found to have a 1.82 g/L concentration of ammonium sulfate, a 0.98 g/L concentration of potassium monophosphate, and a 6.47 g/L concentration of yeast extract. PubDate: 2018-07-01
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