Vol 91, No 6 (2018)

The review deals with greases in which organic ureas of various compositions and structures are used as thickeners. The nature of compounds participating in the synthesis of organic ureas and the main types of polyurea thickeners are considered. The physicochemical, tribological, and operation properties of plastic polyurea lubricants are discussed.

Coagulating effect of titanyl sulfate on a mixed aqueous dispersion of microcrystalline cellulose and TiO₂ was examined. The particle retention on a filter and the filtration rate of the microcrystalline cellulose‒TiO₂‒TiOSO₄ ternary system were evaluated in a wide range of pH values.

Methods of X-ray diffraction analysis, electron microscopy, and microanalysis were used to examine the phase composition and structure of sulfate-anion-containing titanium dioxide samples into which a modifier was introduced by impregnation and by the sol-gel technique. It was demonstrated that the modification of titanium dioxide by the impregnation method results in that an ordered surface structure is formed, which is constituted by accreted crystallites 8–10 μm in size. In this structure, sulfate anions are stabilized at interblock boundaries. Titanium dioxide modified by the sol-gel method has the form of loosely packed coarse aggregates with sizes of about 30–32 μm. The appearance of the titanium tetrasulfide phase mostly situated on the surface was observed in its composition. The microstructural features and, in particular, enrichment of the surface of a sol-gel sample with sulfur and a decrease in dispersity are determined by the catalyst preparation conditions.

CaCl₂ encapsulated was placed in the hydrothermal reactor of an aqueous solution of Na₂CO₃ and dodecyl dimethyl benzyl ammonium bromide for synthesis of two samples of calcium carbonate by an improved hydrothermal method and one-pot method. Their crystal structure, morphology, chemical composition, and thermal stability of the synthesized samples of calcium carbonate were investigated by XRD, FTIR, SEM, EDS and TGDSC. The sterilization activity of the as-prepared samples was evaluated by killing of Sarcina lutea bacteria. The results indicated that the regular cube capsule-assisted calcium carbonate prepared by hydrothermal process was doped with dodecyl dimethyl benzyl ammonium bromide. Under the same condition, the spindle-shaped calcium carbonate synthesized the one-pot method was not doped with dodecyl dimethyl benzyl ammonium bromide. Among the samples of calcium carbonate, capsule-assisted calcium carbonate had shown better antibacterial effect for Sarcina lutea: in 48 h after its inhibition a zone diameter was 12.3 mm.

Electrochemical process of atmospheric oxygen concentration in a modified electrolytic cell with a solid polymeric electrolyte and cathode depolarized by atmospheric oxygen was experimentally studied. The influence exerted by various factors (catalyst hydrophobicity, temperature, pressure, and air supply rate) on the process efficiency was examined. It was shown that the energy consumption for obtaining high-purity oxygen in this process can be reduced by 50–75% as compared with obtaining oxygen by electrolysis of water. The highest activity was observed for Pt40V catalyst (40 wt % Pt on Vulcan XC-72 carbon black) containing 10 wt % fluoroplastic.

Results are presented of an electrophoretic deposition of thin-film coatings based on doped barium cerate BaCeO₃ on a cathode substrate La₂NiO₄ (LNO), which are of interest for the technology of medium-temperature solid-oxide fuel cells. Suspensions for electrophoretic deposition in a mixed dispersion medium isopropanol/acetylacetone = 70/30 vol %, prepared from microsized powders BaCe_0.8Sm_0.2O_3–δ (BCSO) and BaCe_0.89Gd_0.1Cu_0.01O_3–δ (BCGCuO) synthesized by the citrate-nitrate method, demonstrated a high positive ζ-potential (+25 mV) suitable for deposition. A combination of the ultrasonic treatment and centrifugation made it possible to diminish the hydrodynamic diameter of BCSO and BCGCuO particles to 880 and 294 nm, respectively. It was shown that the BCGCuO film deposited onto an LNO cathode substrate has a higher density as compared with the BCSO film, which is due to the properties of the suspensions obtained. Upon a cyclic electrophoretic deposition in six stages, the total mass and thickness of the BCGCuO coating were 3.2 mg cm^–2 and 5 μm, which is sufficient for a unit solid-oxide cell to be formed. According to SEM data, the BCGCuO film is dense and has fully formed grains with sizes of 1 to 7 μm. Methods are discussed for eliminating the loss of Ba in sintering of a thin film based on BaCeO₃.

Transformations of granules based on kaolin and phosphoric acid under the conditions of vapor-phase crystallization at 170°C were studied. Specific features of the individual and cooperative action of a water vapor and a template dipropylamine on the granules were determined. It is shown that the regulation of competing processes of formation of dense non-porous phases (tridymite, cristobalite, berlinite) and microporous crystalline silicoaluminophosphates of structural types ATL and ATN can be carried out by creating transport pores in the volume of the initial granules. The formation of transport pores was provided by using of porogens (hydroxyethyl cellulose and carbon nanospheres) with the subsequent calcination of the granules. The presence of 40- and 60- nm macropores in the porous structure favored intensification of mass-exchange processes occurring within the granules under the vapor-phase crystallization conditions. This led to an increase in the selectivity of crystallization of the materials with crystal structure types AEL and ATN. The morphology of the crystals with the AEL and ATN structure and their chemical composition depend on the porogen used to prepare the starting granules.

The conversion of n-C₇H₁₆, n-C₄H₁₀ and mixtures of C₇H₁₆: n-C₄H₁₀ = 1: 0.3 on the composite catalysts Al₂O₃/WO₄^2– ∙ZrO₂ (A-WZ) and HMOR/ WO₄^2– ∙ZrO₂ (M-WZ) at atmospheric pressure, H₂/hydrocarbon = 3 and temperatures of 140-200°C was studied. It was found that a mixture of C₇H₁₆: n-C₄H₁₀ on M-WZ with high selectivity is converted into C₅–C₆ isomers. An assumption was made about the mechanism of the formation of the bimolecular intermediate C11, which decays earlier than occurs the formation of the products of the conversion of the mixture C₇H₁₆: n-C₄H₁₀.

Oxidative transformations of the ethane–ethylene fraction of oil refinery gases, containing 20 vol % C₂H₄, on VMoTeNb oxide catalyst in the temperature interval 330–450°C were studied. Comparison with oxidative transformations of the individual components (oxidative dehydrogenation of C₂H₆ and oxidation of C₂H₄) shows that ethylene does not noticeably influence the ethane conversion, whereas ethane strongly suppresses the ethylene conversion. The maximal yield of ethylene from the ethane–ethylene fraction is close to that reached in oxidative dehydrogenation of ethane under similar conditions and amounts to 70–72%.

Specific features of the tandem hydroformylation–acetalization of a series of unsaturated compounds and polyols in the presence of a water-soluble catalytic system containing a rhodium catalyst precursor, sodium (triphenylphosphino)trisulfonate, and sulfuric acid were studied. The process parameters (component ratio, temperature, reaction time) were optimized using model substrates. With the suggested catalytic system, the conversion of unsaturated compounds to target products, acetals, reaches 95%, and the catalytic system can be separated from the reaction products and repeatedly used without significant loss of the activity. The acetal preparation procedure is versatile with respect to the raw materials. Batches of acetal mixtures were prepared by the suggested procedure from 1-octene and polyols (ethylene glycol, glycerol, sorbitol).

ZSM-5 (core)/SAPO-11 (shell) composite molecular sieve was synthesized by the hydrothermal method in order to combine the advantages of ZSM-5 and SAPO-11 for the methylation of naphthalene with methanol. For comparison, the mechanical mixture was prepared through the blending of ZSM-5 and SAPO-11. The characterization results indicated that ZSM-5/SAPO-11 composite molecular sieve exhibited a core–shell structure, with the ZSM-5 phase as the core and the SAPO-11 phase as the shell. The pore size of the composite was between that of ZSM-5 and SAPO-11. The composite had fewer acid sites than ZSM-5 and mechanical mixture while more acid sites than SAPO-11. The experimental results indicated that the composite exhibited high catalytic performances for the methylation of naphthalene with methanol.

In this work, we report the development of novel amino-functionalized Fe₃O₄ hybrid microspheres adsorbent from a facial and one-step solvothermal route by using FeCl₃·6H₂O as a single iron source and 3-aminophenoxy-phthalonitrile as ource of amino groups. During solvothermal process, the nitrile groups of 3-aminophenoxy-phthalonitrile would bond with the Fe₃O₄ through the phthalocyanine cyclization reaction to form the amino-functionalized Fe₃O₄ magnetic nano-material, which was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermo-gravimetric analyzer (TGA). From the scanning electron microscope (SEM) and transmission electron microscopy (TEM) observation, the resulting monodispersed amino-functionalized Fe₃O₄ hybrid microspheres with the diameters of 180–200 nm were synthesized via the self-assembly process. More importantly, as-prepared Fe₃O₄ nano-materials with abundant amino groups exhibited high separation efficiency when they were used to remove the Cu(II) from aqueous solutions. Furthermore, the adsorption isotherms of Fe₃O₄ nano-material for Cu(II) removal fitted the Langmuir isotherm model, in which the calculated maximum adsorption capacity could increase from 5.51 to 16.25 mg g^–1 at room temperature. This work demonstrated that the amino-functionalized Fe₃O₄ magnetic nano-materials were promising as efficient adsorbents for the removal of heavy metal ions from wastewater in low concentration.

Radiation-induced telomerization of tetrafluoroethylene in mixtures of trifluoroethanol and Freon 113 with ethanol at room temperature was studied. Tetrafluoroethylene telomers with different mean chain length and terminal hydroxy groups were obtained. The properties of the telomers were studied by thermal gravimetric analysis, elemental analysis, and IR spectroscopy. The reactive hydroxy groups in the telomers improve the properties of hydrophobic coatings and composites prepared from them owing to enhanced adhesion of the telomeric coating to the support and to formation of chemical bonds with the matrix of fluorine-containing composite materials, in particular, of those based on epoxy resins.

The efficiency of a new approach to structural-chemical modification of unsaturated thermosetting resins was demonstrated by the example of curing of rolivsans containing small additions (0.5–2.0 wt %) of aromatic tetracarboxylic dianhydrides and aromatic tetraamines. As shown by dynamic mechanical and thermal analysis, the heat resistance of the modified matrix of the cured rolivsan, which is mainly used as a heat-resistant polymer compound for electric insulation, increases from 280 to 340–375°С, and the rigidity parameters decrease by a factor of 3–6, which is of much practical interest.

Magnesium and calcium coordination compounds (dpp-bian)Ca(thf)₄ (1), (dpp-bian)₂Mg (2), and (dpp-bian)₂Ca (3), containing a chelating redox-active acenaphthenediimine ligand, dpp-bian {1,2-bis-[(2,6-diisopropyl)phenylimino]acenaphthene}, were studied as L-lactide ring-opening polymerization catalysts. The interaction of complex 1 with L-lactide in solution was studied by ESR spectroscopy. The solvent effect on the polymerization rate and molecular-mass characteristics of the polymers obtained was demonstrated.