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[en] Upon γ-irradiation, the product of the polycondensation of petroleum asphaltite with formaldehyde has been found to acquire the properties of a macromolecular initiator for grafting macromolecular chains of acrylic acid. Radiation-resistant ion-exchangers based on the grafted polymer have been prepared
[en] Studies were carried out to reduce the leakage current of high-voltage ZnO varistor ceramics by varying Sb2O3 and NiO content in a ZnO-Bi2O3-Sb2O3-Al2O3-Co3O4-NiO. It was found that the ceramic composition (wt %): ZnO 80, Bi2O3 5.83, Sb2O3 2.62, A12O3 4.66, Co2O3 3.80, NiO 3.09, has a minimum leakage current density Iout ≤ 0.1 μA cm-2, breakdown voltage Ub = 4.1kV mm-1, nonlinearity coefficient α = 65. The resulting ceramics are promising for the production of varistors with high stability of performance.
[en] A ZSM-5 base is used to produce light olefins in the process of converting ethylene to propylene, as well as Ni-W/ZSM-5 to improve the catalyst. After loading the Ni-W/ZSM-5 0.5,1,2 wt % by inoculation, the modified catalyst was investigated for accurate determination of the specification by SEM, BET, FTIR analyzes. The activity of this catalyst was evaluated in the process of ethylene to propylene conversion in a constant reactor under operational conditions (temperature 400°C, pressure 1 atm, and feed flow rate of 0.5 cm3/min of pure ethylene), which also shows the results of tests of catalyst activity evaluation. The selectivity of ethylene and propylene over the modified catalyst will increase as the temperature rises and the maximum selectivity will be achieved at 400°C. The catalyst with 0.5 wt % Ni/ZSM-5 has the highest conversion rate and better selectivity than that with other percentages, also the catalyst with 2 wt % Ni-W/ZSM-5 has the highest conversion rate and better selectivity than other percentages.
[en] Results are presented of experimental studies of the conversion of products formed in gasification of wood, peat, coal-wastes, and shale rock via the partial oxidation by air in a flow-through filtration converter filled with various kinds of porous packing. Charcoal ZPS zeolite and Raschig porcelain rings served as a packing. It was possible to experimentally select for all kinds of packing the modes in which the combustion heat of the conversion products is not lower than that of the starting gaseous products. The conversion of pyrolysis tars was 60–85% and depended insignificantly of the type of a packing. The experimental results were compared for products formed in gasification of wood and coal waste with the data calculated in terms of the thermodynamic conversion model. The satisfactory correspondence between the results of a thermodynamic calculation and experimental data was obtained for products formed in gasification of wood, in which the content of pyrolysis tars is rather high.
[en] The modification of natural rubber with poly(diallyldimethylammonium chloride) and polyvinyl chloride by mixing latexes was studied. It was established that coagulation with polyelectrolyte contributes to preservation of non-rubber components and reduction of the Mooney rubber viscosity, and the introduction of polyvinyl chloride increases the oil and gasoline resistance of the compositions. The revealed effects are explained by the influence of the natural rubber microstructure and polyvinyl chloride on the macroscopic properties of their blends.
[en] Process of thermolysis of sodium borohydride dihydrate samples produced from solution and via a vapor was considered. A study of an acetonitrile solution made by the method of nuclear magnetic resonance demonstrated that the stoichiometry is observed in both cases. An X-ray diffraction analysis evidenced that the sample produced via a vapor is defective. It was found that, in both cases, the process begins after the reaction of peritectic decomposition of the starting compound occurs and a liquid phase is formed. The enthalpy of the peritectic reaction was determined to be ΔHreact = 18.6 ± 1.5 kJ mol−1 for the sample crystallized from an alkaline solution. For the sample produced via a vapor, this quantity is substantially smaller. The kinetics of a low-temperature thermolysis (40–80°C) of both samples is described by the Avrami—Erofeev equation.
[en] Method of coprecipitation with a subsequent thermal treatment was used to synthesize highly dispersed Mn2O3-Bi2O3-ZrO2-CeO2 solid solutions. The elemental and phase compositions, texture characteristics, dispersity, and morphology were examined. The thus synthesized samples exhibit a high activity in the reaction of CO oxidation. It was shown that the nature of doping ions (Bi3+, Nd3+, Sn3+, Gd3+) affects the catalytic activity of the materials. The highest catalytic activity was observed for the Gd0.05Bi0.05Zr0.18Ce0.72O2 sample.
[en] Chromatography-mass-spectrometry was used to examine the stability of admixtures of C1−C7 hydrocarbons, fluorine and chlorinated derivatives of hydrocarbons, alkyl derivatives of silane, homologs of monosilane, and siloxanes in monosilane in its storage in molybdenum-glass ampules and stainless-steel cylinders. It was found that, in the case of storage in glass ampules, the concentration of ethylene and tetrafluoroethylene admixtures decreases and that of ethyl silane and disilane increases. When monosilane is stored in a stainless steel cylinder, the concentration of the acetylene admixture it contains changes.
[en] Additives for diminishing the content of carbon monoxide in gases formed in regeneration of the cracking catalyst without noble metals were synthesized and tested. As additives of this kind can serve mixed oxides based on copper, cerium, magnesium, and aluminum and manganese oxide supported by gamma aluminum oxide. Additives based on mixed oxides possess a high acidity and do not impair the activity of the catalytic system in the cracking reactions. In the efficiency (89.7–95.5%) in lowering the content of carbon monoxide, mixed oxides based on copper and cerium are comparable with the platinum-based additive KO-10 (96.8%). The activity of the additive based on manganese oxide depends on the sample calcination temperature, with the maximum efficiency in lowering the content of carbon monoxide (88.0%) reached at temperatures of 850–920°C.
[en] Spectrophotometric method was used to study the kinetics of the process in which aqueous solutions of selenurea of various compositions are oxidized. Significant differences between the stabilities of selenurea solutions were revealed in relation to the selenurea concentration and also to the acidity, or alkalinity of a medium. It was shown that the stability of selenurea solutions is affected by additives of various antioxidants: sodium sulfite Na2SO3, ascorbic acid C6H8O6, hydroxylamine chloride NH2OH·HCl, hydrazine hydrate N2H4·H2O, and tin chloride SnCl2·2H2O. It was found that using a 1 : 1 mixture of antioxidants Na2SO3 and C6H8O6 substantially raises their antioxidant activity and stabilizes the aqueous solutions of selenurea during up to five days. A hydro-chemical precipitation in the acetate—ethylenediamine reaction system in the presence of the antioxidants under study was used to obtain lead selenide films of stoichiometric composition with thicknesses of 230‒670 nm. With the Na2SO3 + C6H8O6, Na2SO3, C6H8O6, and SnCl2 antioxidants used to stabilize selenurea solutions, a tendency is observed toward a decrease in the lattice constants of PbSe films from 6.1531 ± 0.0003 to 6.1367 ± 0.0002 Å, an increase in the share of nanosize particles, and rise in the PbSe energy gap width from 0.78 to 1.0 e V.