Home – Home – Jornals – Advanced Search

The samples of MoS₂ with added small amounts of polar liquids were synthesized for the first time by means of soli-phase mechanical activation of commercial molybdenite. Physicochemical characteristics of the catalysts are discussed that have been measured by means of sedimentation analysis, XSA, XPES, TEM, thermal analysis. The high activity of the catalyst with small added amount of methanol was discovered in the model reaction of dibenzothiophene hydrogenolysis. It is demonstrated that the level of detect content does not determine the hydrodesulphurising ability of monocatalysts in the model reaction. Interconnection between the physicochemical characteristics of the catalysts and their activity in the model reaction was studied. Conclusions concerning the reaction routes were made on the basis of analysis of the composition of hydrodesulphurising agents by means of gas chromatography-mass spectrometry.

The interaction of solid bismuth oxohydroxonitrates having the composition [Bi₆O₄(OH)₄](NO₃)₆ x 4H₂O (I), [Bi₆O₅(OH₃)](NO₃)₅ x 3H₂O (II) and [Bi₆O₄(OH)₄](NO₃)₆ x H₂O (III) with the aqueous solutions of citric acid was studied by means of X-ray phase analysis, electron microscopy and atomic emission spectroscopy. The conditions for the formation of bismuth citrate having the composition BiC₆H₅O₇ were determined.

Mechanochemical synthesis of anhydrous sodium thiosulphate Na₂S₂O₃ was carried out for the first time by means of mechanical activation of the stoichiometric powder mixture of sodium sulphate (Na₂SO₃) and sulphur (S) in the ball planetary mill “Aktivator-2SL”. By means of iodometric titration, X-ray phase analysis and thermal analysis, it was established that under relatively mild conditions of mechanical activation for about 1 h the degree of transformation in the solid-phase reaction Na₂SO₃ + S = Na₂S₂O₃ reaches 95 %.

For steel and copper as example, the processes of structure formation are considered, taking place under the conditions of intense plastic deformation which is initiated by different kinds of dynamic loading in the zone of contact between the metals of different kinds. It is shown that intense plastic deformation promotes an increase in mutual solubility metals in each other and the formation of atomically ordered phases. In the case of ultrahigh pressure, the formation of atomically ordered phases was not detected. This is connected with the fact that the free atomic volume in the liquid phase, formed in the cumulative jet, exceeds the free volume during solid-phase interaction. A set of the models of structure formation under the gradient conditions can be united within the framework of the scheme “shear-turn”.

Effect of the nature of decomposition of the particles of cobalt azide deposited in the pores of carbon matrix on the phase composition and particle size characteristics of the products is considered. Porous carbon material of Sibunit type, of TU-145 grade (pore diameter 10-15 nm) was used as the matrix. The studies were carried out by means of X-ray diffraction, X-ray fluorescence analysis, complexometry, and thermogravimetry. It was established that mainly the Co₃O₄ phase is formed as a result of the slow decomposition of cobalt azide nanoparticles, while the product of explosive decomposition contains the metal phase and CoO.

Dependencies of the critical energy density of the initiation of explosive decomposition of PETN-Co nanocomposite on nanoparticle radius and the duration of the pulse of the first harmonics of neodymium laser were calculated using the microfocal model of thermal explosion. For each pulse duration, the minimal values of the critical energy density for the initiation and the corresponding radii of nanoparticles were determined. The calculation was carried out in two versions: 1) with the coefficient of absorption efficiency equal to 1, which is independent of nanoparticle radius; 2) taking into account the dependence of absorption efficiency coefficient on the radius of cobalt nanoparticle in a transparent matrix with the refractive index equal to 1.54 (PETN), calculated within the framework of Mie theory. For pulse duration shorter than 100 ns, calculation results differ substantially: neglect of the regularities of absorption by cobalt nanoparticles leads to a decrease in the minimal energy density by a factor of more than 17 for pulse duration 0.1 ns, while taking into account the dependence of the coefficient of absorption efficiency on particle radius, the energy threshold in this range decreases only by a factor of 3. The account of the dependence of laser pulse absorption efficiency coefficient on nanoparticle radius allows solving the paradox of small particles.

Products of the interaction of diphenolic compounds (diph) hydroquinone, resorcinol, pyrocatechin with silicon oxide with the formation of chains of the general formula diph-(Si(OH)₂-diph) _n were studied by means of computer modeling. For each compound, inertia radius and other spatial characteristics were calculated; the fractal dimensionality was determined within the row of compounds. It was concluded on the basis of the results that for the compounds of hydroquinone and resorcinol series the shape of the polymer chain is a rod, while for the pyrocatechin series its shape is a stochastic clew.

Supramolecular structure of arabinogalactan and its complexes with betulin diacetate was studied. Using the methods of small-angle X-ray scattering and laser ablation, the presence of arabinogalactan associates in solution was demonstrated. The formation of these associates may proceed due to the interaction either with water molecules or with betulin diacetate molecules.

Effect of mechanical activation of brown and oxidized coal in the presence of alkaline reagent and abrasive material in different concentrations was demonstrated. Solid-phase mechanochemical reactions of humic acids with the salts of heavy metals were carried out. The features of structural transformations of humic acids during mechanical activation were revealed.

Effect of the conditions of mechanochemical activation on the efficiency of enzymatic hydrolysis of carbohydrates incorporated into highly lignified plant raw material - reed stem biomass was studied. Complicated supramolecular structure and high lignin content in the structure have a negative effect on enzymatic hydrolysis. The model conditions of fragile grinding and plastic deformation of the material under different temperature of mechanical activation are considered. The samples obtained by mechanical activation of lignocellulose material are characterized by increased reactivity in enzymatic hydrolysis due to an increase in the surface area and disordering of the crystalline regions in cellulose. Optimal conditions for mechanical activation of plant raw material for obtaining highly reactive products were established.