Vol 90, No 10 (2017)

The whole set of available data on the thermodynamic properties of liquid alloys and solid phases in the sodium–tellurium system is considered, beginning from the first study in 1970 and till the recent reports in 2015. The application of the sodium–tellurium system in chemical power cells is discussed.

It is shown that nickel–phosphorus–graphite composite coatings can be deposited by the autocatalytic deposition method. The optimal concentration of graphite and the duration of ultrasonic treatment of a graphite suspension in solution for deposition of composite coatings based on the nickel–phosphorus alloy were determined. The influence exerted by thermal treatment parameters on the properties of the deposits was examined. The optimal process conditions are suggested.

Reduction of zirconium dioxide with boron carbide and nanofibrous carbon in argon yielded a highly dispersed powder of zirconium diboride. Characteristics of zirconium diboride powders were examined by various analytical methods. The material obtained is represented by a single phase, zirconium diboride. Powder particles are for the most part aggregated. The average size of particles and aggregates is 10.9–12.9 μm with a wide size distribution. The specific surface area of the samples is 1.8–3.6 m² g^–1. The oxidation of zirconium diboride begins at a temperature of 640°C The optimal synthesis parameters were determined: ZrO₂: B₄C: C molar ratio of 2: 1: 3 (in accordance with stoichiometry), process temperature 1600–1700°C, synthesis duration 20 min.

Surface of silicon oxide (white black BS-120) was hydrophobized with a polymethylhydrosiloxane solution. IR spectroscopy demonstrated that the hydrophobization process involves free silanol groups of the silicon oxide surface. It was found that a stable superhydrophobic state of the surface is observed upon hydrophobization of silicon oxide, with the wetting angle exceeding 150°. Introduction of hydrophobized silicon oxide into a fire-extinguishing powdered formulation based on ammonium phosphates can improve its rheological characteristics. The influence exerted by the fraction composition of dispersed systems based on phosphorus-ammonium salts on their rheological properties was examined.

Specific features of the double-stage process in which unsaturated compounds and, in particular, fatty acid methyl esters of vegetable oils are epoxidated with peroxyacetic acid obtained ex situ in aqueous solutions of acetic acid and hydrogen peroxide under catalysis with Amberlyst 15 Dry ion-exchange resin were examined. It was shown that the independently occurring processes in which the peroxy acid is heterogeneously catalytically formed and epoxy compounds are synthesized can substantially raise the formation selectivity of epoxides with respect to double bonds in fatty acid methyl esters and simplify the simulation of these processes and their technological implementation.

The current work is focused on the testing of titanium modified hexagonal mesoporous silica (HMS) for catalysts in epoxidation of cyclohexene. Two samples were prepared via the chemical liquid deposition (CLD) and the chemical vapor deposition (CVD), namely Ti/HMS-L and Ti/HMS-V, respectively. HMS and Ti/HMS were characterized by XRD, N₂-adsorption, ICP-AES, UV-Vis. The samples were also evaluated by the epoxidation of cyclohexene with cumene hydroperoxide (CHP) as oxidant. It is revealed that Ti/HMS samples possess typical hexagonal mesoporous structure in which most of titanium species exist in the form of framework tetracoordinated state. Meanwhile, Ti/HMS-V is more seriously affected than Ti/HMS-L since the former was prepared at higher temperature. Ti/HMS-V gives more excellent catalytic performance than Ti/HMS-L, which is likely because the former has more isolated and framework titanium species. Either Ti/HMS-V or Ti/HMS-L can be used only 1 time in epoxidation experiment.

In this work three different supports (γ-Al₂O₃, ZSM-5, and SAPO-34) of varying degree of acid sites and textural properties were used to evaluate the influence of support specifics in the Cu/supported nanocatalysts on NO conversion. The nanocatalysts were prepared by homogeneous deposition precipitation (HDP) method and characterized by N₂ pore size distribution, TEM, H₂-TPR for investigation the reducibility of the copper species and acidity measurement by NH₃ adsorption. The Cu/ZSM-5 and Cu/SAPO-34 catalysts were more active for NO conversion than Cu/γ-Al₂O₃ catalyst. The characterization and conversion differences in the copper supported on different types of support indicated that these differences arise from the differences in surface area, pore size distribution, and acidity of the supports. The higher SCR-DeNO activity of Cu/ZSM-5 and Cu/SAPO-34 nano-catalysts can be explained by higher surface area and acidity of ZSM-5 and SAPO-34 supports. These catalysts also have larger amount of reducible Cu species compared to Cu/γ-Al₂O₃ which correlates with the structure of the support used. Considering these findings, the NO conversion ability of Cu/supported catalysts has been correlated with support structure and acidity.

Electrospinning is a simple and effective technology for fabricating nanofibers and polymer blending provides strength and minimal defects of electrospun ones. Therefore, in the present study, fabrication, and characterization of nylon-6/gelatin electrospun nanofibers using low-toxic solvents was investigated as means to improve the morphological deficiencies of gelatin nanofibers and facilitate its electrospinnability. The morphology of electrospun nylon-6/gelatin nanofibers were characterized using scanning electron microscope (SEM). SEM results showed that electrospun blend nanofibers had smooth surface with average diameter of from 40 to 100 nm; while, the miscibility of the blend and thermal behavior of nanofibers were determined using Fourier transform-infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC). Water contact-angle measurement (WCA) was employed to investigating the wettability of nanofibers.

The influence of the hydrogen partial pressure varied in the interval (4.3–100) × 10³ Pa on the kinetics of liquid-phase catalytic hydrogenation of aromatic mononitro compounds in the presence of platinum and iridium supported on activated carbon in various percent ratios (Pt/C-2.5% and Ir/C-5%) was studied for 3,4-dichloronitrobenzene as example. A decrease in the hydrogen partial pressure leads to a significant decrease in the rate of the nitro compound consumption and in the yield of the intermediate arylhydroxylamine. A kinetic mechanism of hydrogenation of the nitro compound, satisfactorily describing the experimental data, was suggested.

A modification of a solution method for preparing solid oxide electrolyte films was developed. It is based on using a suspension consisting of a solution of inorganic salts and of a nanodispersed precursor powder prepared from the same solution. As demonstrated by the example of calcium zirconate, this procedure allows the number of applications of the liquid-phase precursor, required to obtain a dense electrolyte film on a porous support, to be considerably decreased relative to the procedure using a salt solution. The influence of the concentration of the precursor powder in the suspension on the microstructure of CaZr_0.9Y_0.1O_3–δ films was analyzed.

The effect of introducing 1–3 wt % copper oxide sintering additive on the electrical and electrochemical characteristics of promising anode materials for solid oxide fuel cells based on Sr₂Fe_1.5Mo_0.5O_6–δ was studied. The total conductivity increases with increasing amount of copper oxide. The maximum conductivity in humid hydrogen at 800°C, 45 S cm^–1, was reached on introducing 3 wt % CuO. The sintering additive enhances the electrochemical activity of Sr₂Fe_1.5Mo_0.5O_6–δ and Sr₂Fe_1.5Mo_0.5O_6–δCe_0.8Sm_0.2O_1.9 anodes. A decrease in the sintering temperature of the anodes containing CuO with the electrolyte based on lanthanum gallate directly correlates with the electrochemical activity of the anodes. The minimum value of the polarization resistivity, 0.15 Ω cm² at 800°С in a humid hydrogen atmosphere, was obtained for the composite anode with 3 wt % CuO sintered at a temperature of 1050°С.

Modified polysaccharide was synthesized by the reaction of amylopectin with a cationic monomer, (1,2-epoxyprop-3-yl)triethylammonium chloride, in alkaline solution in the presence of Fenton’s reagent. The influence of the concentrations of amylopectin, gelatin, their polymer-inorganic hybrids, and modified pectin on their flocculating properties in free (unrestricted) sedimentation of ocher suspension as a model disperse system was studied. Amylopectin exerts a stabilizing effect, whereas the modified pectin and polymer-inorganic hybrid exert a flocculating effect. The influence of the mode of introducing polymer additives on the flocculating effect and aggregation of ocher particles was analyzed.

Ways to decrease slagging of the solid residue from peat combustion in the filtration combustion mode were studied. Addition of silicon oxide to the fuel considerably reduces the ash slagging. The melting points of the ash residues from fuels of different compositions were determined.

Composite hydrogels based on polyacrylamide immobilized nanoparticles of commercial (P25 brand) titanium dioxide and of titanium dioxide nanoparticles prepared by electric explosion of a wire were synthesized. The enthalpy of interaction at the polyacrylamide/TiO₂ interface was determined by microcalorimetry using the thermochemical cycle method. Interaction of polyacrylamide polymer chains with the surface of TiO₂ nanoparticles is energetically unfavorable. The absence of interactions between the hydrogel polymer network and surface of TiO₂ nanoparticles favors manifestation of the UV-induced photocatalytic activity of TiO₂ nanoparticles immobilized in the hydrogel. Immobilization in the polyacrylamide hydrogel matrix decreases the photocatalytic activity of P25 brand TiO₂ nanoparticles, but does not affect the photocatalytic activity of titanium dioxide nanoparticles prepared by the electric explosion method. The photocatalytic activity of TiO₂ nanoparticles immobilized in the bulk of polyacrylamide hydrogel evaluated by the decomposition of Methyl Orange dye is controlled by the diffusion rate of the dye molecules into the bulk of the hydrogel and depends also on the aggregation of TiO₂ nanoparticles in the hydrogel matrix.