Key Engineering Materials Vol. 670

Abstract: This article deals with the study of direct current (DC), ultrasonic, and of electrolyte of the influence on the change of titanium dioxide sorption properties. The TiO₂ prepared by the TiCl₄ hydrolysis method. Attention is drawn to charging exchange processes the surface of titanium dioxide particles after they pass through a layer of counter ions in an aqueous medium under the influence of a DC. The stages of the end product’s formation using methods of the X-ray diffraction, the differential thermal and the infrared spectrometric and the gas adsorption analysis were proposed. Dependence of redistribution sorption active centers at the surface of TiO₂ was proved.

Abstract: The double complex compounds - hexa (isothiocyanate) chromates (III) of lanthanide (III) complexes with ε-caprolactam and nicotinic acid [Ln (ε-C₆H₁₁NO)₈][Cr (NCS)₆] and [Ln (C₅H₅NCOO)₃(H₂O)₂][Cr (NCS)₆]·nH₂O, n=1,2 - were produced from the aqueous solutions by means of direct synthesis. The substances are studied by the spectroscopic method; their crystal structure is determined. It is found that all the complexes are of island ionic type. ε-C₆H₁₁NO complexes form triclinic system crystals - space group P ̄1, or monoclinic - space group С2/с. The nicotinic acid compositions crystallize in the monoclinic system, space group P2₁/n. The complexes have reversible heat-sensitive properties and can serve as the chemical sensors in the temperature-sensitive devices that are used for visual inspection of the thermal regime in various technological processes.

Abstract: Different methods are used to prepare gallium-containing zeolites of a ZSM-5 structure. Their acidic and structural characteristics are investigated and the effect of the method of gallium introduction into a zeolite on distribution and ratio of acid sites of different strengths, as well as on pore volume and diameter is determined. The relationship between the localization of gallium introduced into a zeolite by different methods and its electronic state and the catalytic activity and selectivity of the resulting contacts in the course of propane aromatization is established. The Ga-containing zeolite prepared by impregnation is found to be the most efficient catalyst for conversion of propane into aromatic hydrocarbons.

Abstract: The influence of fibrous and solid granulated fillers on the rheological and surface properties of the polymer compositions on the basis of polyvinyl alcohol and Na-carboxymethyl cellulose is demonstrated. The polymer complexes with Na-carboxymethyl cellulose and sodium tetraborate additions and the compositions filled with polypropylene, polyethylene terephthalate and quartz sand are obtained and comparative assessment of the properties of studied polymer composites have been made. Polymer compositions with quartz sand, synthetic and plant fibrous fillers increase the effective viscosity, elasticity modulus and decrease the adhesive strength of all compositions based well on carboxymethyl cellulose and polyvinyl alcohol. The sodium tetraborate introduction promotes the formation of the composites surface with the lesser adhesive strength.

Abstract: The authors have synthesized nanofibrous aluminum oxyhydroxide (AlOOH), modified with different amounts of manganese ions (II), which is the precursor for methane deep oxidation catalysts. It was shown that the catalytic activity of the manganese-based system obtained depends on manganese amount and thermal activation conditions. It is approved that as the catalyst for deep oxidation of hydrocarbons the system with manganese content of 10.5 wt. % is the most perspective despite the fact that the oxidation rate of methane is lower in it than in the catalyst with Mn content of 5.7 wt. %. As opposed to the catalyst with Mn content of 5.7 wt. %., where the aluminium oxide is in metastable form (s-Al₂O₃), the catalyst with manganese content of 10.5 wt. % contains in its structure a thermodynamically and thermally stable α-Al₂O₃ phase.

Abstract: Nickel dispersion, which provides total catalytically active metal surface, is significant for partial catalytic oxidation of natural gas to obtain high purpose products yield and productivity in syngas. The interaction of reaction medium under high reaction temperatures during 20-25 hours promotes the increase of total square of active Ni component for block catalysts obtained with self-propagating high-temperature synthesis, which allows achieving productivity in syngas 7.1·10³ cm³ (syngas)/cm³(catalyst)·hour. It is observed that for catalyst systems obtained with precipitation, chemical composition of oxide phase influences the particles size of metal nickel. For granular catalysts obtained through precipitation after 25-hour exploitation, average particle size (according to CSR) metal nickel is 3-4.5 times smaller than Ni in catalysts obtained with self-propagating high-temperature synthesis. This allows achieving productivity in syngas 8.1·10³ cm³/сm³·hour, when there is average temperature decrease over the catalytic layer by ~100°С in comparison with blocks acquired through self-propagating high-temperature synthesis.

Abstract: The effect of EOR technologies on the contents of petroporphyrins and naphthenic acids in recovered crude oil was studied using heavy oil from Usinskoye oil field (Republic Komi), which has high density, high content nickel and vanadium porphyrin complexes, the oxygen compounds and naphthenic acids. It is found that EOR system in combination with thermal steam treatment injection brings about an increase in the content of vanadium porphyrin complexes of crude oils. As a result of the oil-displacement EOR system injection, the naphthenic acids content would decrease in heavy oils.

Abstract: The paper studies the formation of thin-film and disperse SiO₂-M_xO_y systems (where M – Mn, Fe, Co, Ni) synthesized with sol-gel technology. The influence of metal salt on tetraethoxysilane hydrolysis and film-forming solution viscosity is considered. Dependence of the film optical properties on their composition was determined.

Abstract: In the paper, the particle morphology is considered and the slices of phase diagrams of nanosystems agreeable to the synthesis conditions are constructed according to the data obtained earlier by authors, as well as new results of the study of nanostructured Fe-Co, Fe-Ni, Co-Ni, Fe-Co-Ni, Fe-Pt, Cu-Ni and Ni-Cd powders. It is found that all considered polymetallic systems have common nature of the particle size spatial organization, i.e., 7-20 nm nanocrystals (for different systems) form highly compact aggregates (40-100 nm) which put together into loose porous agglomerates (up to 200-250 nm) and then into unconsolidated micron size formation of cloud type. It is classified uncovered features of nanostructured polymetallic phase diagrams in comparison with phase diagrams of bulk systems. Magnetic properties of nanosystems are studied.