Том 92, № 12 (2018)

The maximum yield of cinnamyl alcohol (80%) was achieved on a 1% Pt/CeO₂–ZrO₂ catalyst based on the support pre-calcined at 400°C with the largest specific surface area (108 m²/g) and the smallest Pt nanoparticle size (4 nm). The dependence of the surface area of cerium-zirconium supports on the thermal treatment conditions and its effect on the activity of supported catalysts was shown.

The possibilities of improving the strength characteristics of alloys based on aluminum and niobium are studied. It is established that the use of scandium allows finely dispersed hardening intermetallide phases to be obtained. The maximum effect of dispersion hardening is observed upon annealing an alloy with the composition Al 99.0 at %, Nb 0.7 at %, and Sc 0.3 at % for 54 h at 300°С.

In this work, we have prepared a new catalytic system based on highly dispersed Pt nanoparticles supported on mesoporous ceria-zirconia oxide. The unique ability of the synthesized catalyst to activate hydrogen in the temperature range from –50 to 25°C allows us to provide selective hydrogenation of nitro-aromatic compounds to anilines at room temperature and atmospheric pressure of H₂.

Conditions of crystallization are determined for the MIL-53 (Al) (AlOHbdc, bdc = benzene-1,4-dicarboxylate) microporous metal–organic framework. Three major factors responsible for the formation of a pure phase of MIL-53(Al) are identified. These include the temperature (above ~120°С) and the nature of the solvent. It is established through powder diffraction that using microwave radiation for the activation of the reaction mass leads to the formation of a material with higher phase purity, in contrast to preparation techniques that employ conventional heating (hydrothermal synthesis and synthesis under atmospheric pressure).

A catalyst containing iron oxide particles on the surface of palladium nanoparticles is synthesized for the first time using a redox method of the catalytic reduction with hydrogen. The activity of the catalyst in the selective hydrogenation of phenylacetylene considerably increased, compared to the initial palladium catalyst.

A systematic analysis was performed of the physicochemical properties of amorphous silicas (Acros, Degussa, KSKG) and CrO_x/SiO₂ catalysts prepared from them with 2, 3, 5, 7, and 10 wt % chromium. The supports and catalysts were characterized by BET, XRD, and UV–Vis diffuse reflectance spectroscopy. In the oxidative dehydrogenation of propane with carbon dioxide, the highest propylene selectivity (95%) was observed for the 5% CrO_x/SiO₂ (Degussa) sample, and the highest propane conversion (53%) was reported on the 5% CrO_x/SiO₂ (Acros) catalyst. The structure of chromium oxide particles on the support surface was studied by UV–Vis spectroscopy. The catalytic properties were correlated with the state of chromium.

Supported monometallic Fe/SiO₂ and bimetallic Fe–Cu/SiO₂ catalysts were synthesized by incipient wetness impregnation. The synthesized catalytic systems were studied in selective hydrogenation of phenyl-acetylene with molecular hydrogen under mild reaction conditions (H₂ pressure 1.3 MPa, 80–110°C). The catalytic properties of monometallic samples depend on the conditions of thermal treatment. The best results on the selectivity of styrene formation (78%) at complete conversion of phenylacetylene were obtained on the reduced sample, in which iron was in the metal state. The modification of the iron oxide phase with copper (0.4 wt %) makes it possible to exclude the stage of reduction of FeO_x to Fe⁰ in hydrogen at high temperatures and to retain high catalytic activity and attain styrene selectivity of 78%.

A correct way of calculating the equilibrium surface tension of planar and curved vapor–liquid interfaces is formulated for the first time according to Gibbs (i.e., as the excess free energy in the region of immiscible phase transitions). Calculations are performed using a modified lattice gas model that reflects a discrete–continuous distribution in the space of mixture components. The discrete size scale is associated with regions of around the size of a molecule that form the cells of the lattice structure. The continuous scale corresponds to the intermolecular motion of components inside the cells. The intermolecular interactions of comparable components are considered in a quasi-chemical approximation that describes direct correlations. It is shown that considering only the discreteness of the molecular distribution on a rigid lattice does not provide simultaneous satisfaction of two special conditions of chemical and mechanical equilibria for any degrees of interface curvature, and that the conditions of phase partitioning are insufficient for unambiguous calculations of the surface tension. The condition for the complete equilibrium of two phases must be supplemented with the conditions of the local mechanical and chemical equilibria at each point of the boundary transition region, and the local pressure value must be adjusted to the local value of the chemical potential.

Based on the stoichiometry of absorption, a thermodynamic approach is proposed for describing the nonexchange sorption of substances with ion exchangers from individual solutions and mixtures. This approach is applied to describe the absorption of amino acids using the sorption of tryptophan and hystidine with anion exchangers AV-17-2P in Cl form as an example. Integral and differential characteristics of nonexchange sorption in these systems are described.

Using hydrogen oxidation as a model reaction, it is shown that the ignition of combustible gases upon heating in the region of atmospheric pressure is caused by a chain avalanche reinforced by self-heating of the reaction mixture, which becomes marked as combustion develops. The functional character of the temperature dependence of the rate of the chain reaction outside the region of ignition differs fundamentally from the Arrhenius law.

Activity and selectivity of heterogeneous biomimetic catalysts per-FTPhPFe(III)OH/Al₂O₃ and PPFе(III)OH/Al₂O₃ towards particular compound have been studied during the process of gas-phase oxidation of cyclohexane and its mixture. Varying process parameters (temperature, H₂O₂ concentration, contact time) has provided an opportunity to obtain a common understanding of the active influence of these catalysts during the oxidation of cyclohexane in the mixture with its derivatives, where their selective action towards cyclohexane has also been observed. On the basis of the experimental research of the process of cyclohexane monooxidation, it has been found out that a complex reaction takes place on the biomimetic catalyst. This complex reaction consists of parallel-sequential monooxidation and oxidative dehydrogenation reactions that are coherently synchronized with H₂O₂ decomposition reaction. Possible mechanisms of cyclohexane biomimetic conversion to the target products are presented. The unity of the mechanisms of acid-base catalysis and the redox system based on the principle of CBR (chain of bond rearrangement) which is typical of enzymatic catalysis can be traced during this conversion. Depending on the process parameters, it is possible to consciously control the direction of the monooxidation reaction and its rate.

We investigate the Schrock–Osborn catalyst, [Rh(COD)(PPh₃)₂][PF₆], in a series of ionic liquids by XPS. The electronic environment of the rhodium centre is demonstrated. The subtle change of the electronic environment of the rhodium centre due to the catalyst-ionic liquids interaction is revealed based upon Rh 3d binding energy. It suggests that the anion of ionic liquids can have significant impact on the electronic environment of the rhodium centre.

The enthalpies of dissolution of crystalline nitrilotrimethylphosphonic acid С₃Н₁₂NO₉Р₃ (NTPA) in water at 298.15 K are determined calorimetrically. The standard enthalpies of formation of nitrilotrimethylphosphonic acid and products of its stagewise dissociation in aqueous solutions are calculated.

The liquid-liquid extraction of cobalt(II) from sulfate media (Na₂SO₄) with substituted salicylideneanilines (SAN) is investigated. The stoichiometry of the extracted complexes formed in the organic phase is evaluated. It was found that the cobalt is coordinated with three ligands (L), and composition of the extracted complex is: CoL₂HL and cobalt is coordinated with two ligands (L) in case of substituted SA as CoL₂. The values of the extraction constants were calculated and analyzed in terms of the nature of the substituents.

A number of hypercrosslinked polystyrene networks are studied. The networks are obtained via additional crosslinking of granules of styrene copolymer with 0.5% divinylbenzene (0.3–0.5 mm) and microgranules with 1% divinylbenzene (3.5 µm) using monochlorodimethyl ether to densities of crosslinking from 60 to 500%. It is found that as the degree of crosslinking grows, the absorption in the electronic spectrum of the polymer extends to the visible region, and the granules change color (toward as dark as black); this phenomenon is much less expressed for microgranules and milled materials. For a consistent explanation of these two observations, assumptions are made about the appearance and increase in the contrast of density fluctuations of a tracery hypercrosslinked network and light scattering on such micro-inhomogeneities in the volume of particles of the compared series of polymers.

This research demonstrates the stability of linkage isomers of [1,2-H₂-3,3-(CO)₂-3-X-closo-3,1,2-ReC₂B₉H₉]; X = η¹-NO, η²-NO, η¹-ON by the use of MPW1PW91 quantum method. The singlet and triplet states were considered for studied complexes. Structural parameters, HOMO-LUMO gap, energies of frontier orbital and vibrations modes of CO and NO ligands were explored in linkage isomers in two states of spin. Moreover, the interaction of bonding between the NO⁺ with [1,2-H₂-3,3-(CO)₂-closo-3,1,2-ReC₂B₉H₉]^– fragment, NO^– and [1,2-H₂-3,3-(CO)₂-closo-3,1,2-ReC₂B₉H₉]⁺ fragment was analyzed using the energy decomposition analysis (EDA). Nucleus-independent chemical shift (NICS) values were determined at the center of carborane indicate aromaticity of cage.

Porous composites of different phase composition are synthesized via oxidation in a water–ethanol mixture of bimetallic Al/Zn nanoparticles obtained through a joint electrical explosion of aluminum and zinc wires in an argon atmosphere. It is found that the oxidation of aluminum and the formation of boehmite nanosheets proceed in solutions containing 7‒20 wt % of water. At water contents over 20 wt %, the almost complete oxidation of aluminum is followed by the onset of zinc oxidation, resulting in the formation of composites containing boehmite nanosheets and hexagonal plates enriched with zinc oxide. Composites synthesized in this way display high antimicrobial activity against bacteria, due mainly to the release of Zn²⁺ ions into the solution. The greatest antimicrobial activity is observed in composites that simultaneously contain AlOOH, Al, ZnO, and Zn phases. The strong migration of Zn²⁺ ion is due to the structure of these composites, in which the active zinc surface grows as a result of the availability of ZnO plates located between the boehmite nanosheets. The boehmite nanosheets ensure stability of the composite structure and electrostatic interaction with bacteria.

A mathematical model of solid-phase chemical synthesis in a binary powder mixture is constructed and studied with allowance for the shrinking of the mixture and the change in the reaction surface as a result of particle caking. Relations are obtained to estimate the number of similar and dissimilar interparticle contacts. Depending on the parameters of the mixture (the stoichiometric ratio between components, the particle size ratio, and the porosity), different modes are revealed that affect the rate of chemical transformation. The optimum conditions for an intense chemical interaction are determined.

The adsorption properties of SO₂ molecule on the surface of pyridinic nitrogen doped graphene (4NG), M/4NG and M/2NG (M = Al, Li, Si) are investigated using density functional theory. The adsorption energies have been calculated for the most stable configurations of the molecule on the surface of 4NG, M/4NG, and M/2NG. It is found that M/4NG (M = Al, Si) have significant adsorption energies than that of pyridinic nitrogen doped graphene and M/2NG (M = Al, Si). The doped Li atom did not enhance the interactions between the 4NG and SO₂. Furthermore, connecting distance and net electron transfers give the evidence that the SO₂ stay on M/4NG (M = Al, Si) by chemisorption. Significant changes in density of states (DOS) show the existing of noteworthy orbital hybridization between SO₂ and M/4NG–SO₂ (M = Al, Si) during adsorption process which is proving to strong interaction while there is no evidence for hybridization between the SO₂ molecule and 4NG. Compared with 4NG, Al/4NG, and Si/4NG may be promising adsorbent for practical applications.

The effect hydrocarbonates and chlorides, the most common anions in natural and waste waters, on the oxidation of bisphenol A by persulfate activated with iron ions and simulated solar radiation is studied. It is established that hydrocarbonates have an inhibiting effect due to deactivation of Fe²⁺ ions and non-target expenditure of the in situ generated reactive oxygen species by reactions with hydrocarbonates. It is found that chlorides have a promoting effect: the reaction of bisphenol A oxidation is accelerated by 1.25–1.4 times, and the degree of mineralization grows by 18–44%. The established patterns are in good agreement with the existing data for real aqueous systems (surface waters of lakes Baikal and Gusinoe).

Amphiphilic zinc oxide (ZnO) was successfully prepared by modifing neat ZnO with silane coupling reagent KH-570. The modified ZnO and neat ZnO were characterized by measurement of the lipophilic degree value; Fourier transformed infrared spectroscopy (FT-IR), ultraviolet-visible (UV–Vis), X-ray diffraction (XRD). The results showed that KH-570 was successfully coated on surface of the neat ZnO, as a result, the modified ZnO was amphiphilic. Compared with neat ZnO, amphiphilic ZnO has a better compatibility with the organic solvent and its photocatalysis ability for oil degradation was enhanced by 28%. The improved oil degradation performance of amphiphilic ZnO can be explained by its hydrophobic property, which is benefit for absorbing oil in water.

Microemulsions based on biocompatible components with high water content are applied to increase the solubility of medicinal drugs of the heterocyclic series indomethacin and 1-[5-(4-chlorophenyl)-3-phenylpyrrole-2-yl]benzimidazole-2(3H)-one (PBI). The solubilizing capacity is characterized quantitatively via spectrophotometry. It is shown that four-component microemulsion water/oleic acid/Tween 80/ethanol increases the limits of indomethacin solubility by more than two orders of magnitude, and that of PBI by more than three orders relative to water.

The Gibbs energies of transferring succinic acid from water to aqueous ethanol and aqueous dimethylsulfoxide solvents are determined according to solubility. An increase in the negative values of the Gibbs energy upon moving from water to aqueous–organic solvents is observed. The effect the composition of solvents has on the acid–base properties of succinic acid is analyzed using the thermodynamic solvation approach. It is shown that the main contribution to the shift of the acid–base equilibria of succinic acid in aqueous ethanol and aqueous dimethylsulfoxide comes from the weakening of the solvation of its deprotonated forms.