Advanced Materials Research Vol. 1085

Abstract: Humic substances are the major components of soil, peat and brown coal. They can be fractionating into fulvic acids (FA), brown humic acids (BHA) and gray humic acids (GHA). In this work we investigated the influence of mechanochemical modifications on structural composition of HAs main fractions using the methods of IR and ¹H MRS spectroscopy. The IR spectroscopy results has shown that HA has different chemical composition in comparison with GHA and BHA. Potentiometric titration showed that mechanoactivation (MA) with thiourea increases the amount of oxygen-containing groups up to 2.5. For the first time we studied the impact of modifying agent of thiourea on the structural composition and acid-base properties of HAs major fractions - GHA and BHA during the mechanoactivation process.

Abstract: The synthesis of controlled dispersity nanopowders is a vital nanotechnology task. This paper describes how the type of surfactants used during the hydroxide precursor Co (OH)₂ precipitation influences the dispersity of cobalt nanopowder obtained by the process of hydroxide reduction. It has been determined that the usage of surfactants may both increase and decrease the nanopowders dispersity: when using 0.1 wt.% “cetylpyridinium chloride – no surfactants – EDTA sodium salt – polyethylene glycol – sodium lauryl sulfate” surfactant solutions, during the precipitation process the specific surface of the obtained metallic nanopowder was equal to “3.7 – 4.5 – 5.0 – 6.0 – 9.5 m²/g”, respectively.

Abstract: In this work the effect of substrate and vaporization temperatures on the structural parameters (sizes of coherent scattering region, values of strain), phase and chemical composition, surface morphology of Co films is revealed. Co films were deposited on Si (100) substrates by Metal-organic chemical vapor deposition using the diiminate complex Co (N’acN’ac)₂ as a precursor. The sizes of coherent scattering region, values of strain and phase composition of Co films were determined by the X-ray diffraction analysis. The chemical composition was identified by the Energy-dispersive X-ray spectroscopy. The surface morphology of Co films was investigated by scanning electron microscope. It is found that the variation of deposition conditions allows us widely to change structural parameters and chemical composition of Co films.

Abstract: An influence of support acidity on the dimerization function on Pd-containing catalysts was studied. After addition of Re₂O₇ to PdO/SZ as ethylene dimerization catalyst with high butene-2 selectivity the obtained PdO-Re₂O₇/SZ catalyst was tested in direct synthesis of propylene from ethylene under mild conditions (40°C and atmospheric pressure). Propylene yield was approximately 45%, which is close to equilibrium one.

Abstract: In this research, a new approach is used to identify the products of electrochemical oxidation of UV visible substances over solid electrodes. In order to determine the product of phenol electrooxidation over glassy carbon electrode, the results obtained using voltammetric method and photoluminescence spectroscopy have been compared. It was proved that in an alkaline solution phenol is present in form of phenolate-ion, adsorbing on the surface of glassy carbon electrode, and oxidized to hydroquinone with transfer of two electrons.

Abstract: Cuprum-zinc catalysts with chrome and zirconium additives were obtained by continuous codeposition within this study. XRD showed the presence of cuprum, zinc, chrome, and zirconium oxides phases. Catalytic activity was studied under the mixed loading with HZSM-5 zeolite as a catalyst for methanol dehydration during the STD-process reaction. TPR method was used to show that the reduction of catalysts takes place up to 350 °С. The maximum СО conversion value for sample CuZnAl amounts to 60 %, for sample CuZnAlСr - 83 %, and for sample CuZnAlZr it is 68 %. DME yield amounted to 18 % at a temperature of 240 °С for sample CuZnAl, for CuZnAlZr – 15 % (Т=240 °С), and for CuZnAl – 11 % at 220 °С.

Abstract: The results of studies to determine the parameters affecting the morphology of the particle formation in certain conditions plasma chemical synthesis are present. On the example of oxides of cerium and yttrium were determined kinetic characteristics of plasmachemical process for their preparation, calculated characteristic times of the main stages occurring in the plasma-chemical reactor (t₁, t₂, t₃, t₄). Have been proposed parameter K₀, characterizing the modes of hollow and solid particles formation and determining the process of salt diffusion in the droplet volume and solvent evaporate from the surface.

Abstract: Results of plasmodynamic synthesis of silicon carbide nanopowders are given in the article. Studies of the synthesis product by X-ray diffractometry and transmission electron microscopy indicated that the product consists mainly of cubic silicon carbide and also includes cubic silicon, ultradispersed graphite and carbon onion-like structures. It was shown that a phase composition change in the synthesis product is possible by changing the ratio of precursor mixture.

Abstract: The fractal dimension of a large group of nano-silica, alumina, titanium oxide, and Gd₂O₃ and Y₂O₃ was calculated by means of original program. Nanopowders of used oxides are created in two main ways, such as evaporation substances by relativistic electron beam and high temperature hydrolysis. The fractal dimension was calculated upon transmission electron microscopy images obtained with different magnification. It was managed to establish that it's possible to make a comparative assessment of the degree of hydrophilicity of the nano-silica's samples by means of attitude fractal dimension to the specific surface.