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Two new isomeric complexes [CuBr2(R-bian)] (R = 4-Me-Ph (1), 2-Me-Ph (2)) were obtained by reacting copper(II) bromide with 1,2-bis[(2-methylphenyl)imino]acenaphthene ligands and characterized. The crystal structure of 2 was determined by X-ray diffraction analysis. The copper atom has a distorted square-planar environment; the ω angle between the CuN2 and CuBr2 planes is 37.004°. The calculated ω parameters for optimized structures 1 and 2 were 76.002° and 43.949°, indicating significant deviations from the ideal tetrahedral and square-plane geometries, respectively. Molecules 2 form dimers due to non-covalent Cu···Br contacts, which were analyzed by DFT calculations. The complexes were also characterized by cyclic voltammetry and UV-Vis spectroscopy. A quasi-reversible Cu(II)/Cu(I) redox event with E1/2 potentials of 0.81 and 0.66 V (vs. SHE) was found for 1 and 2, respectively. The electronic absorption spectra showed the presence of Cu(I) species as a result of the partial reduction of the complexes in the acetonitrile solution. Both complexes were tested as homogenous catalysts for the oxidation of isopropylbenzene (IPB) in acetonitrile at low temperatures. Differences in the mechanism of the catalytic reaction and the composition of the reaction products depending on the oxidizing ability of the catalyst were revealed.

Ordered mesoporous MgAl2O4 support was synthesized by one-pot evaporation-induced self-assembly method with block copolymers. Nanocomposite catalysts were prepared by loading this support with PrNi0.9Ru0.1O3 perovskite or Ni + Ru-doped Ce0.35Zr0.35Pr0.3O2 fluorite oxides. Their texture, structure, surface properties and reactivity have been studied by combination of modern structural, spectroscopic and kinetic methods. Suppression of MgAl2O4 support acidity, strong interaction of small Ru-Ni alloy nanoparticles with the surface layers of this support modified by perovskite and fluorite oxides with a high oxygen mobility and reactivity provide a high activity and stability to coking and sintering of these catalysts in all studied reactions of methane and ethanol transformation into syngas. Ni + Ru/Ce0.35Zr0.35Pr0.3O2/MgAl2O4 active component loaded on honeycomb Fechraloy foil substrate demonstrated a high performance and stability to coking in autothermal natural gas oxi-dry reforming, ethanol steam reforming and autothermal reforming of ethyl acetate in concentrated feeds promising for the practical application.

Highly dispersed LaCo

Nanostructured powders xFe/nano-Al2O3 with the Fe loading of x = 0,0–5,0 wt% were obtained using laser vaporization by a cw CO2 laser. XRF, XRD, HRTEM, PL and UV-vis DRS techniques were employed to investigate physicochemical, structural and optical properties of the synthesized nanopowders with the average particle size of 9 nm. Nanopowders xFe/nano-Al2O3 as model catalysts were tested in isobutane dehydrogenation reaction. The results obtained were compared with similar data for the xFe/γPb-Al2O3 systems synthesized by the conventional sol-gel method. According to XRD and UV-vis DRS data, in the series of xFe/nano-Al2O3 samples a great part of Fe3+ ions is in the disordered environment of subsurface layers of Al2O3 nanocrystallites predominantly in tetrahedral coordination. In distinction to samples of the xFe/γPb-Al2O3 series, in the case of nanostructured xFe/nano-Al2O3 powders the formation of Fe2O3 phase does not occur at any concentrations of iron or conditions of testing. The analysis of the PL spectra of xFe/nano-Al2O3 powders also showed the presence of surface sites of Fe3+ ions, which were not detected for xFe/γPb-Al2O3. Catalytic testing of the xFe/nano-Al2O3 series samples in isobutane dehydrogenation revealed the formation of the iron active sites that ensure catalytic activity of the samples. Differences in the catalytic properties of FeOx/Al2O3 samples obtained by the sol-gel method and laser vaporization are related to different states of Fe3+ ions. Thus, the xFe/nano-Al2O3 nanopowders in contrast to xFe/γPb-Al2O3 contain a large amount of active Fe3+ sites. These sites involved in the dehydrogenation reaction are present predominantly on the surface of the nanopowders.

Multi-walled carbon nanotubes (MWCNT) and alumina supported CоMо hydrotreating catalysts prepared with citric acid as a chelating agent (CoMoS/MWCNT-citr and CoMoS/Al2O3-citr respectively) were studied. MWCNT supported catalyst prepared without chelating agent (CoMoS/MWCNT) was also investigated. The addition of citric acid in MWCNT supported catalyst decreases the average slab length of MoS2 from 4.2 to 3.0 nm without increasing the stacking, while the differences in sulfidation degree and MoS2 promotion by cobalt are not observed. The activity of MWCNT-based catalyst in dibenzothiophene hydrodesulfurization (HDS) increases with the addition of citric acid due to improved dispersion of sulfide component. The activity in naphthalene hydrogenation does not change. The results of comparative study of MWCNT and Al2O3 supported catalysts prepared with citric acid show that the catalysts have rather similar morphology of sulfide phase: average slab length of about 3 nm and average stacking number of 1.6-1.7. At the same time, in MWCNT-based catalyst, active metals are sulfided more easily and CoMoS phase is formed at higher extent due to weaker metal-support interaction. CoMoS/MWCNT and CoMoS/Al2O3-citr catalysts are both highly active in HDS and demonstrate similar conversion of dibenzothiophene. The highest HDS activity of CoMo/MWCNT-citr catalyst is attributed to the beneficial effect that is provided by the combined use of carbon support (higher sulfidation degree and higher CoMoS phase content) and citric acid (improved dispersion of sulfide component).

Effect of nanosized silicon on mechanical properties, texture, and structure of a polymer paint-and-varnish coating made of gray KhV-16 enamel based on perchlorovinyl and glyphthalic resins is studied. It is established that the abrasion strength, hardness, and elastic modulus are larger than in the case of the original coating. Various methods are used to analyze the structure of the resulting samples of paint-and-varnish coatings. It is established that the structure changes and the mechanical properties of the coatings improve because of the formation of new structure-forming centers in the composite coating due to the addition of nanosized silica.

Platinum catalysts supported onto bayerite alumina were synthesized and studied. Alumina of the θ-Al2O3 type, which was prepared from metallic aluminum by an aluminate method, was used as a support, and platinum(IV) nitrate and hydrogen hexachloroplatinate(IV) precursors containing Pt4+ ions were used for supporting an active component. The catalysts were studied by physicochemical methods such as X-ray phase analysis, X-ray photoelectron spectroscopy, transmission electron microscopy, and ultraviolet-visible diffuse reflection spectroscopy. It was found that platinum occurred in a finely dispersed state in both of the catalysts, and it was uniformly distributed over the support surface. The particle sizes were 2.8 and 0.9 nm in the samples synthesized from platinum(IV) nitrate and hydrogen hexachloroplatinate(IV), respectively. The most uniform surface distribution, high dispersity, and a narrow particle-size distribution were obtained with the use of hydrogen hexachloroplatinate(IV). The catalysts were tested in the partial oxidation of natural gas. The catalyst synthesized using platinum(IV) nitrate afforded an almost thermodynamically equilibrium distribution of the reaction products of partial oxidation at a temperature of 700–800°С.

The optimal conditions for the synthesis of platinized graphitic carbon nitride (Pt/g-C3N4) have been found. It was investigated as a catalyst for the production of hydrogen from aqueous solutions of triethanolamine (TEOA) under irradiation with visible light. The highest photocatalytic activity of 450 μmol h−1 g−1 and an apparent quantum efficiency of 1.1% were demonstrated by the 1% Pt/g-C3N4 sample prepared from melamine by calcining at 600 °C for 2 h.

Isotherms of Ge(IV) and Cu(II) ions sorption on to the weakly basic anion-exchange resin AN-31 from chloride solutions have been constructed and described. The dependence of equilibrium parameters of Ge(IV) and Cu(II) ions sorption from chloride ions concentration was shown. Based on the electron spectra of diffuse reflectance of copper-containing sorbent, isotherms of sorption and isomolar copper–germanium ions distribution diagram in solutions with different chloride concentrations the nature of extracted particles has been established, and the effect of the mineral background on the sorbent capacity has been determined. The synergistic effect of Cu(II) ions sorption in the presence of Ge(IV) ions has been established. It was found that the ionic and uncharged associates formed by hydroxy-chloride polynuclear cuprate(II) cations and methagermanate anions extract from the chloride solutions onto AN-31. The possibility of selective Cu(II) ions sorption from germanium containing 1 M chloride solutions in wide range of Ge(IV):Cu(II) molar ratios from 1:3 to 1:1 has been established.

BACKGROUND: Preparation of homogeneous oxide coatings on the surface of fiberglass is a difficult task due to hydrophobicity of the fiberglass support. NiO‐TiO₂ cannot coat the fiberglass surface homogeneously. In the present study, SiO₂ was added in the NiO‐TiO₂. A sol–gel method was used to prepare Ni‐Si‐Ti sol and this was used to coat fiberglass and form a complex Ni‐Si‐Ti oxide system supported on its surface. The catalyst was tested for hydrocarbon oxidation reaction. RESULTS: The as‐prepared material is a mixture of TiO₂ in the anatase modification and SiO₂ in the amorphous phase. UV‐visible diffusion reflectance spectroscopy confirmed the presence of Ni²⁺Oₕ cations in the film bulk. Introduction of silica to the sample ensured a uniform distribution of the NiTi oxide system on the fiberglass surface and its durable retention there at 600 °C. The Ni‐Si‐Ti mixed oxide supported on fiberglass demonstrated a higher catalytic activity in the oxidation of n‐heptane, compared to NiTi oxide/fiberglass catalyst. It is stable even at 600 °C, the temperature at which the maximum n‐heptane conversion of 93% was reached. CONCLUSION: Adding SiO₂ in NiO‐TiO₂ can coat fiberglass homogeneously as SiO₂ can coat hydrophobic surfaces such as fiberglass. This research provides a method with which to coat metal oxide catalyst on fiberglass that is very active and stable for oxidation of hydrocarbons even at high temparatures, compared to that without adding SiO₂. © 2019 Society of Chemical Industry

A comprehensive study of optical and catalytic properties of highly dispersed single-phase η-, γ- and γ*-Al2O3 ([Cr3+] ∼ 10–4 wt.%) powders and the related model chromia-alumina catalysts with different chromium content ([Cr3+] = 0.25, 0.5 and 1 wt%) was carried out. The catalytic characteristics (product yield, conversion and selectivity) in isobutane dehydrogenation to isobutylene were measured for all the samples under consideration. The surface Cr3+S luminescence centers were detected by photoluminescence spectroscopy in all the samples. The content of Cr3+S centers in the samples was estimated before and after isobutane dehydrogenation. It was shown that the amount of surface Cr3+S centers correlates with isobutylene yields of the reaction. Among the studied samples, the maximum amount of Cr3+S luminescence centers was found for the model 1% Cr/γ-Al2O3 catalyst. This sample has the highest values of isobutane conversion and isobutylene yield. The comprehensive study of the Cr/Al2O3 systems made it possible to propose a method for predicting the catalytic activity of nanostructured materials using the photoluminescence detection of surface luminescence centers and their quantitative evaluation.

Calcined CoMo/γ-Al2O3 hydrotreating catalysts were reactivated by a solution of citric acid and triethylene glycol. The reactivated catalysts were tested in HDS of dibenzothiophene and hydrotreating of SRGO. The reactivated catalysts were showed a significant increase in activity compared to calcined. The highest reactivation was observed for the sample reactivated using a solution of citric acid and triethylene glycol. All catalysts were characterized by means of UV-DRS, FTIR, Raman spectroscopy, XRD, XPS, and HTREM. It has been shown that the addition of triethylene glycol increases the proportion of CoMoS phase and the dispersion of sulfide particles.

We have studied interaction between the microwave activation product of gibbsite and an aqueous cobalt nitrate solution at room temperature, atmospheric pressure, and pH 8.0 ± 0.3. The results demonstrate that, under such conditions, the reaction in the near-surface region of the microwave-activated gibbsite particles leads to the formation of an aluminum cobalt oxyhydroxide with fragments of spinel structure and the composition Со2.3Al0.7O4, and a Со6 –xAl2 –x(OH)1.5 · 3.5H2O (0 ≤ x ≤ 1) nonstoichiometric hydrotalcite. The morphology of such compounds is determined by 2D nanoparticles in the form of bent sheets 2–5 nm in thickness and 500 nm or more in length. After calcination at 500°C, the composition of the reaction products corresponds to the aluminum cobalt oxide Со2.3Al0.7O4 with the spinel structure.

LnZrOx (Ln: La, Sm) mixed oxides of Ln: Zr = 1 were prepared by different methods (complex polymerized method, sorption of cations on starch from aqueous salt solution and conventional co-precipitation with additional redispersion of precipitate by ultra sound) and calcined at 700–1300 °C. Their specific structural features and changes were studied and discussed. Various characterization methods were used such as X-ray diffraction, Electron microscopy, Fourier-transform infrared and Raman spectroscopy, UV–Vis spectroscopy, X-Ray absorption fine structure and X-ray photoelectron spectroscopy.The formation of pyrochlore structure occurred at 1100–1300 °C from fluorite-like pseudocubic phase ZrO2 regardless the method of preparation. This phase had a block-like structure consisting of ZrO2 nanocrystals stabilized by Ln cations and residual anions such as hydroxyls and carbonates. The desorption of such anions with heating already started at 900 °C and lead to local changes of Zr cations coordination to octahedral and to the formation of pyrochlore nanodomains inclusions within fluorite-like phase. The increased cation mobility and further elimination of anions caused by further heating was accompanied by the formation of bulk pyrochlore phase at 1100–1300 °C. Even after calcination at 1300 °C the local microheterogeneity as well as defects were identified at domains boundaries or sintered microstructure. These specific features of the formed pyrochlores depend on the method of preparation. Keywords: Fluorites, Pyrochlores, Synthesis, Powders, Structure

CoMoB/Al2O3 catalysts with up to 2 wt.% of B have been synthesized by two different methods an introduction of boron into γ-Al2O3 support during the kneading of the paste or by the impregnating of γ-Al2O3 extrudates by the solution of Mo and Co compounds, citric and boric acids. It is shown that the activity in HDS and HDN of diesel fuel increases with increasing boron content in catalysts. The growth of the activity is associated with the increase in CoMoS phase content, Co dispersity, an average slab length of sulfide active component particles and an average number of slabs per 1000 nm2. The positive effect of boron is much more pronounced for catalysts prepared by the introduction of boron to the solution, since boron is located preferentially on the surface of alumina particles.

Perovskite-type samples La1-xCaxCo1-xTixO3/KIT-6 (x = 0–0.5) were synthesized by citrate method. KIT-6 is partially embedded in the perovskite structure. The complete reduction of cobalt in perovskites in the presence of KIT-6 occurs at a temperature of ca. 670 °C due to the formation of a cobalt silicate phase. With the substitution of titanium for cobalt cations, the complete reduction of cobalt occurs at temperatures above 720 °C. The proportion of cobalt that is reduced at temperatures below 500 °C increases with an increase in the ratio of Co3+/Co2+ cations. Partial substitution of cobalt cations with titanium cations decreases the selectivity ratios SCH3OH/SC2+OH and SCH4/SC2-8. The introduction of calcium cations leads, proportionally to its content, to a strong decrease in selectivity to methanol and an increase in selectivity for light hydrocarbons C2-8 in syngas conversion. It was shown that the maximum selectivity for higher alcohols with a low selectivity for methanol is observed at x = 0.3 on a sample containing calcium. A significant amount of the cobalt carbide phase Co2C in the used KIT-6-free sample of LaCoO3 is accompanied by the predominance of the methanation reaction (CH4 selectivity 58.7%). The synthesized samples on KIT-6 have higher selectivity to alcohols compared to a conventional CoAl oxide catalyst and somewhat lower activity in syngas conversion.

Commercial liquid-phase-sulfided type II CoMo/Al2O3 catalyst was reactivated after commercial operation and oxidative regeneration. For this purpose, the use of citric acid (CA) that reactivates a regenerated CoMo/Al2O3 catalyst was studied. The study of the reactivated catalyst was carried out by means of UV-DRS, FTIR, Raman spectroscopy, XRD, XPS, and HTREM. The catalytic activity was estimated in the HDS of straight-run gasoil (SRGO). It was shown that the treatment of the catalyst with CA leads to the formation of a Co–Mo complex compound and significantly reduces the proportion of β-CoMoO4 and MoO3 in the catalyst. Eventually, this leads to the formation of CoMoS phase type II in a higher proportion enhancing the HDS catalytic properties.

During the preparation of stoichiometric LaAlO3 type oxide from an aqueous solution of La and Al nitrate salts, using starch as template, a layered intermediate – disordered mixed lanthanum and aluminum hydroxycarbonate exists in the 300–700 °C calcination temperature range. According to calcination temperature a variable content of anions/OH is observed as well as changes in the coordination environment of La and Al cations are providing distortions in the structure. The nuclei of LaAlO3 appears within a mixed La-Al hydroxycarbonate matrix at ∼700 °C. This phase crystallizes at 900 °C after decomposition of the major part of bulk carbonates. The surface layer of perovskite particles formed by stacked nanocrystallites is enriched in La cations and contains residual hydroxyls and carbonates, which results in distortion of the local environment of both cations creating oxygen defect sites as well. Such a microheterogeneity is partly retained up to 1300 °C.

It is found that the sorption recovery of copper ions from water solutions in the phase of AN-31 low basicity anion exchanger has a mixed character. It is established via diffuse reflectance spectroscopy that ions are stabilized through complexation with the participation of the functional groups of the sorbent with the formation of structures [Cu(NR3)2(OH)2(H2O)2], [Cu(NR3)3(OH)(H2O)2], and as a result of the physical adsorption of oxide dimers and planar-squared copper clusters. It is shown that increasing the ionic strength of a solution by introducing sodium chloride into the system greatly improves the capacity of the sorbent and leads to the uniform distribution of copper ions in the resin matrix. The similarity between the ESR spectrum parameters of copper-containing samples of the ion exchanger, obtained in a wider range of pH, is determined via ESR and testifies to the homogeneity of the stabilization positions of Cu2+ ions. The crystalline field of tetragonal-elongated octahedron is typical of all Cu2+ ions. All of the complexes have Cu(NO3)2 coordination nodes with the covalent bonding of Cu2+ ions and the amine groups of the sorbent.

This paper presents results of a detailed study of fundamental aspects of the formation of 2D and 3D nanostructured YSZ:Yb3+ ceramics with a cubic structure through a key synthesis step in aqueous solutions of zirconium-containing hydroxy nanoparticles (1–2 nm) modified by Y3+ and Yb3+ ions, with the use of a sol–gel method and subsequent calcination of the resultant xerogels at temperatures above 350°C. As starting chemicals for the synthesis of ceramic powders, we used zirconyl, yttrium, and ytterbium nitrates and chlorides and aqueous ammonia. Using mixed solutions of these salts and a procedure developed by us, we synthesized sols, gels, and xerogels. To examine the effect of temperature on solid-state transformations, the xerogels were calcined according to a predetermined program in a muffle furnace at temperatures in the range from 350 to 1350°C (rarely, up to 1650°C). We focused primarily on ceramic powders close in composition to 0.86ZrO2 · 0.10Y2O3 · 0.04Yb2O3. The ceramics were characterized by high-resolution transmission electron microscopy, electron microdiffraction, electronic diffuse reflectance spectroscopy, energy dispersive X-ray microanalysis, and X-ray fluorescence analysis.

The new multi-layered composite was manufactured by deposition of the carbon nanofibers (CNF) at the surface of the glass-fiber fabric, which is pre-modified by application of additional external layers of NiO and porous silica. Carbonization of synthesized catalytic template was performed at 450 °C in propanebutane media at ambient pressure. CNF was deposited in amount of ~130% of initial template mass or 65 g per g of nickel, the specific surface area of the material is ~100 m2/g. The synthesized material has high mechanical strength, high hydrophobicity and strong bonding between CNF and glass-fiber support. The synthesis method is technologically simple, inexpensive and easily scalable. It is possible to manufacture such material in various solid shapes, using the flexibility of the primary glass-fiber support; in particular, it may be used for production of the mechanically self-sustainable catalytic cartridges with required shape and internal geometry using no additional structuring elements.

Rhodium catalysts supported on bayerite and pseudoboehmite alumina, calcined at 800 °С, were synthesized and tested in the partial oxidation of methane. Rhodium (III) chloride was used as an active component precursor. The supports and catalysts were investigated by a wide range of physicochemical methods: XRD, SEM and HR TEM, XPS and UV–vis DRS. In both cases, large rhodium particles with a coherent scattering region size of 15–19 nm are formed, and small ones with dimensions less than 1 nm. On the whole, smaller rhodium particles are formed on the bayerite oxide. The catalyst with pseudoboehmite-type support shows better results in the reaction.

For catalysts comprised of mixed manganese-chromium oxides MnxCr3-xO4 (x = 0.3–2.7) prepared by Pechini route with Ni and Ru supported by impregnation fundamental factors determining their performance in ethanol steam reforming have been elucidated using combination of structural (XRD, HRTEM), spectroscopic (UV–vis), surface science (XPS, FTIR spectroscopy of adsorbed CO) and kinetic (H2 and EtOH TPR, oxygen isotope heteroexchange with C18O2) methods. The most important feature is strong metal-support interaction stabilizing small clusters of metals/alloys and preventing carbon nucleation. The lattice oxygen mobility and reactivity increased with Mn content. The highest TOF was obtained for (Ni + Ru)–loaded oxide support containing cubic spinel phase of MnCr2O4 composition, which implies a positive effect of Ni-Ru interaction in mixed clusters on catalytic activity. This catalyst has also a high density of active sites, surface enriched by Mn and sufficient oxygen mobility providing coking stability, which makes it attractive for practical application.

A complex of physicochemical methods (powder XRD analysis, transmission and scanning electron microscopy, electron spectroscopy of diffuse reflectance, low-temperature nitrogen adsorption) is used for the comparative study of structural and morphological properties of oxide supports Ce1–x M x O y (M = Gd, La, Mg; x = 0-0.5; 1.5 ≤ y ≤ 2.0) for catalysts for the autothermal reforming of bioethanol to a hydrogen-bearing gas. It is shown that Ce1–x M x O y samples synthesized by the method of ester polymer precursors are mesoporous materials being the homogenous substitutional solid solutions with the fluorite-type cubic structure. The structural and textural properties of the Ce1–x M x O y materials are regulated by varying the type of the dopant cation (M = Gd, La, Mg), the molar ratio M/Ce (0, 0.1, 0.25, 1), and heat treatment conditions (temperature 300-800 °C; duration 4-24 h). The relationship between the synthesis parameters and the characteristics of the Ce1–x M x O y materials is found.

The paper presents the synthesis and characterization of highly dispersed titania on the surface of fiberglass material. Scanning electron microscopy and X-ray digital 3D-microtomography showed that each support fiber was uniformly coated by modifying component. The layer of titania consisted of anatase particles of 18 nm, an average pore size was 3.1 nm. The prepared material revealed a catalytic activity in n-heptane cracking, deep and partial oxidation. The major products of n-heptane conversion at 300–400 °C in the presence of oxygen were ketones with a carbon number of 3–4. Above 500 °C, the deep oxidation increased dramatically with a simultaneous appearance of α-olefins.

The novel iron-oxide based glass-fiber catalysts (GFC) for the H2S selective oxidation uses the support in form of the glass microfibrous fabric, premodified by external layer of secondary porous SiO2 support. The specific activity of FeOx-SiO2/GFC catalyst per unit mass of active component exceeds that of the similar conventional Fe2O3/Al2O3 catalyst by more than an order of magnitude due to the more dispersed state of active component in the GFC (1–2 nm compared to 15–30 nm in conventional catalyst). The proposed GFC also looks advantageous in terms of mass transfer efficiency and easy scale-up.

The paper is dedicated to the novel glass-fiber catalysts (GFC) using copper chromite as an active component for the reaction of deep oxidation of hydrocarbons and volatile organic compounds (VOCs). The catalyst support is the glass microfibrous fabric preliminarily modified by the addition of an external layer of silica secondary porous support. Surface thermosynthesis was applied for manufacturing of such catalysts. XRD and UV–Vis DRS studies have demonstrated that the active component in the synthesized GFCs is CuCr2O4 in the structural type of partially inverted spinel. As shown in experiments with the deep oxidation of toluene in air, the specific activity of CuCr2O4/GFC per unit mass of the active component exceeds that of the similar conventional CuCr2O4/Al2O3 catalyst by up to 20–30 times. Such significant rise is explained by both the much more efficient mass transfer in GFC cartridges and the higher intrinsic activity of the copper chromite in the GFC, where the particles of CuCr2O4 have the typical size of 10–25 nm compared to >100 nm in case of conventional alumina catalyst. The proposed GFC looks promising for the abatement of hydrocarbons and VOCs in different waste gases.

Multiwalled carbon nanotubes (MWCNTs) were successfully incorporated inside silica aerogel matrix. Solid composite materials were investigated by high-resolution transmission microscopy, scanning electron microscopy, optical spectroscopy. MWCNTs in the form of small bundles and individual tubes get locked inside the aerogel between its pores resulting in the local solution-free environment for nanotubes. Optical transmission of the composite material can be modified by the amount of the added MWCNTs. Nonlinear optical properties were studied by a Z-scan technique. Composite materials demonstrate saturable absorption for femtosecond laser pulses at 515 nm wavelength that are attributed to the properties of embedded nanotubes. Silica aerogels possess significantly better thermal stability compared to polymer matrices, hosts that are frequently used for saturable absorption applications of carbon nanotubes. Solid and lightweight silica aerogels with embedded nanotubes can be used as optical elements for various photonic devices. Photo of silica aerogel with embedded MWCNTs. Normalized Z-scan transmittance of silica aerogel with nanotubes for two different on-focus intensities.

Reflectance spectroscopic methods the electronic, redox and structural properties of Mn-Na-W/SiO2 catalysts prepared by the incipient wetness impregnation method and mixture slurry method were studied in detail. Since POSS nanotechnology (POSS = polyhedral oligomeric silsesquioxanes) has attracted attention as tooling for synthesis of catalysts with novel properties and functionalities, we expanded this method for the preparation of Mn-Na-W/SiO2 catalyst. The physicochemical and catalytic properties of Mn-Na-W/SiO2 catalysts prepared by conventional methods and POSS nanotechnology were examined comparatively. In all studied Mn-Na-W/SiO2 catalysts both individual oxides (MnOx, WO3) and bimetal oxide phases (Na2WO4, MnWO4) are found in addition to oxide particles of high dispersion. The UV-Vis Diffuse Reflectance indicates that Na+ cations facilitates stabilization of octahedrally coordinated Mn3+Oh cations in the isolated state, while Mn3+Oh promote the disordering of W6+ cations in the supported system. The Mn-Na-W/SiO2 prepared using metal-POSS precursors marks out presence of unglobular SiO2 particles, higher dispersion of MnOx and MnWO4 particles and more easily reducible metal-oxide species. The catalysts prepared by incipient impregnation method and mixture slurry method have practically similar catalytic performance while the catalyst prepared by POSS nanotechnology method shows lower activity and selectivity. At 800‒850 °C the increase of C2 hydrocarbons yield from 4 to 15% and the rise of molar ratio С2Н4/C2H6 from 0.2 to 1 are observed when impregnation or mixture slurry method are used for catalyst preparation instead of POSS nanotechnology method.

A comparative study was performed on the surface properties of silica nanoparticles synthesized by various methods using FTIR, UV-Vis DRS and X-ray diffraction. It is shown that different methods of synthesis affect the surface properties of nanoparticles while maintaining the phase composition of the material. It is also shown that the nanoparticles of each material have unexpected properties. In particular, a significant difference was observed in the concentration of Lewis centres for the samples. This variation in properties indicates the importance of accurately characterizing the surface properties of nanoparticles as they determine the interactions of nanoparticles with other materials.

Start The compared study of the properties of liquid-phase and electric explosion alumina nanoparticles was made. The X-ray diffraction analysis demonstrated that these nanoparticles remain in amorphous and semi-amorphous states. The complete structural information of Al2O3 nanoparticles was obtained as a result of the full-profile refinement of their model phase parameters. The parameters of the unit cells, spatial distribution of atoms, and occupancy of nodes were also determined.The data of IR spectra of surface OH groups and adsorbed CO revealed that the surface imperfection of an electric explosive sample is lower than that obtained using the liquid-phase method. Using photoluminescent spectroscopy, impurities of Cr3+, Mn4+ and Ti3+ in the octahedral oxygen coordination and Fe3+ in the tetrahedral oxygen coordination were detected. It was observed that the concentration of these impurities was significantly higher in the electric explosion sample. Using UV-Vis DR spectroscopy, it was found that the liquid-phase sample was amorphous, and the electric explosive sample was well crystallized and most probably consisted of 2D and 3D nanostructures.

The effect of the substitution of copper ions by titanium ions in LaCuxTi1-xO3 (x = 0.4–0.8) mixed oxide on physicochemical and catalytic properties in syngas conversion was studied. The activation and catalytic testing were accompanied by reduction of part of copper ions and destruction of the perovskite structure leading to the removal of titanium and copper cations. An increase in the titanium content leads to a decrease in the proportion of reduced copper with the preservation of the defective perovskite-like oxide substrate. The application of KIT-6 silica for increasing the surface area essentially enhanced catalytic efficiency of the system. The main product of syngas conversion was methanol; its formation selectivity on the synthesized mixed oxides is comparable to the selectivity on conventional CuZnAl oxide catalyst. With increasing copper content in the samples, the selectivity for higher alcohols increases and contribution of water-gas shift reaction to the total CO conversion rate grows.

Laser vaporized xCr/Al2O3 nanopowders with the particle size of ca. 15 nm were studied by XRF, EDX, HRTEM, XRD, DD, BET, TGA, UV–Vis DRS, Raman and PL spectroscopy methods as a catalytic system in dehydrogenation of isobutane. The nanopowders were found to contain not only the Cr6+ ions located on the surface of nanoparticles, but also two different types of Cr3+ sites as components of the γ-Al2O3 solid solution. One type consists of the bulk Cr3+b sites in a strong crystal field. Another type is represented by the Cr3+s sites residing near the surface of xCr/Al2O3 nanoparticles. Such sites are in a weak crystal field. It was shown that catalytic activity of the nanostructured xCr/Al2O3 system is provided by the high content of surface Cr3+s sites. The results obtained make it possible to propose the nanopowders obtained by laser synthesis as a promising catalytic system that can be used in the development of highly active catalysts for dehydrogenation of alkanes with the decreased chromium content.

For La2Zr2O7/LaAlO3 composite prepared by aging (100 °C/10 h) of the mixture of precipitated precursors of La-Zr-O and La-Al-O, evolution of its structural features after sintering in air in the range of 100–1300 °C was investigated by applying XRD, HRTEM, FTIR, Raman and UV–Vis spectroscopies, 27Al MAS NMR and 139La NMR. The initial composite forms a highly dispersed and disordered structure retaining considerable concentrations of residual anions (anions from the initial salts, water molecules and hydrogen bound hydroxyls) due to basic properties of La cations. Stepwise removal of these anions by calcinations results in the crystallization of La2(Al)O2CO3 at 500 °C with complete disordering of the system after heating at 700 °C. These transitions are accompanied by appearance of AlO4 polyhedra. The La-Zr-O- containing phase appeared for the first time at 900 °C as fluorite-like ZrO2 stabilized by La (Al) cations, and LaAlO3 (P2) phase is also observed along with admixtures of La2O3 and La10Al4O21. At 1100 °C fluorite-like ZrO2 converts into the La2Zr2O7 (P1) phase, and in the range of 1100–1300 °C mixed P1 and P2 oxides are the main phases. For P1 phase, structure becomes more ordered at higher sintering temperatures, while for P2 phase in composite the nanodomain structure is still observed in comparison with individual mixed oxide at 1300 °C. The molecular –scale features of domain boundaries in nanostructured La-Zr-O/La-Al-O composite as well as applied inexpensive method of its fabrication provide required bases for a broad practical application of this material for Thermal barrier coatings (TBCs).

This work is focused on the characterization of a novel vanadium pentoxide catalysts on a glass-fiber support. The catalyst support consists of a non-porous glass-fiber fabric covered with an additional external surface layer of porous secondary support of SiO2. The vanadia active component is synthesized from vanadyl oxalate precursor by means of an impulse surface thermo-synthesis method. Such catalysts demonstrate high activity and appropriate selectivity in the reaction of H2S oxidation by oxygen into sulfur in the practically important temperature range below 200°C. According to the characterization data, the freshly prepared vanadia catalyst partially consists of mostly the amorphous and badly ordered vanadia with some part of the wellcrystallized V2O5 phase. Under the reaction conditions the main part of vanadia in the catalyst remains in the amorphous V2O5 form, while the less part becomes reduces into of VO2 and other vanadium oxides (such as VO, V2O3 V3O7 and V4O9). Most probably, the crystallized V2O5 in course of reaction is responsible for the deep oxidation of hydrogen sulphide into SO2, while the lower vanadium oxides promote the selective H2S oxidation into elemental sulfur.

Mixed nanocrystalline Ce-Zr-O oxides (Ce/Zr = 1 or 7/3) were prepared by modified Pechini route using ethylene glycol solutions of metal salts. Detailed characterization of their real structure and surface properties by X-ray diffraction on synchrotron radiation with the full-profile Rietveld analysis, high resolution electron microscopy with elemental analysis, Raman spectroscopy, UV-Vis and X-ray photoelectron spectroscopy revealed a high homogeneity of cations distribution in nanodomains resulting in stabilization of disordered cubic phase. This provides a high dispersion of NiO loaded on these mixed oxides by wet impregnation, a high reactivity and mobility of oxygen in these catalysts and strong interaction of Ni with support in the reduced state. This helps to achieve a high activity and coking stability of developed catalysts in CH4 dry reforming in feeds with CH4 concentration up to 15% and CH4/CO2 ratio =1.

The morphology and structural and electronic states of nanodispersed copper ferrite-chromites of with different Cr/Fe ratios calcined at 900°C in an atmosphere of air were studied using a set of physical methods. The morphology, the homogeneity of chemical composition, and the degree of perfection of spinels formed from mixed Fe-Cr-Cu hydroxo compounds upon heat treatment were studied by HRTEM. From an analysis of atomic radial distribution curves, it follows that copper ferrite-chromite with a partially inverted spinel structure was formed at the ratio Cr/Fe = 1. With the use of DRS, it was found that all of the Fe-Cr-Cu-containing oxide samples contained Cu2+ cations in tetrahedral and tetragonally distorted octahedral oxygen coordination. In this case, the DRS spectra exhibited a decrease in the absorption energy of Cu2+ cations as the Cr/Fe ratio was decreased from 2 to 1, which indicated a decrease in the tetragonal distortion of the octahedral oxygen environment of the Cu2+ cations. In general, the data on the distribution of cations in Fe-Cr-Cu oxides with different Cr/Fe ratios obtained by EXAFS and DRS are consistent with the results of crystallochemical analysis. It was confirmed that the distribution of Cu2+ cations significantly affected the activation energy of water gas shift reaction.

A comparative study of the scope and surface properties of alumina (Al2O3) and titanium dioxide (TiO2) nanoparticles, synthesized using different methods, was carried out using Fourier-transform infrared spectroscopy (FTIR), ultraviolet UV-Vis diffuse reflection spectroscopy (UV-Vis DRS), and Raman spectroscopy, as well as X-ray diffraction methods. It is shown that the differences in the synthesis methods can change the surface properties of the nanoparticles, while maintaining the phase composition of the material. The nanoparticles of each material are shown to exhibit unexpected properties. In particular, the special luminescence characteristics of TiO2, a photon-energy shift from the rutile region into that region typical for the anatase, and a significant difference in the Lewis center concentration values for the alumina γ-phase were observed. This variation in the properties indicates the necessity to involve a wider range of analysis techniques and the importance of precisely characterizing the surface properties. To identify those nanoparticle functional properties that determine their interactions with other materials, a comprehensive study of their phase compositions and surface properties must be completed.

The stabilization of cobalt cations in zirconium–silica fiberglass materials was studied by X-ray photoelectron spectroscopy, ultraviolet visible diffusion reflectance spectroscopy, and a differential dissolution phase analysis. It was found that the commercial Zr–Si fiberglass material contained a layer of hydrated silicon (the depth of 6 nm) on the surface of the glass fibers. Modification of the fiberglass material with cobalt led to its distribution in the fibers mainly in the Co2+ state. It was shown that 90% of cobalt was stabilized on the surface and in the hydrated silicon layer as Co2+ cations in tetrahedral oxygen coordination, while the remaining 10% was distributed non-uniformly in the bulk of the fibers as Co2+ cations in octahedral oxygen coordination.

Mixed nanocrystalline ceria-zirconia oxides doped with praseodymium containing 5, 7.5, 10, and 12.5 wt. % nickel were prepared by the incipient wetness impregnation of the oxide support. Complex physicochemical characterization by X-ray diffraction analysis, ultraviolet-visible diffuse reflectance spectroscopy, high resolution transmission electron microscopy and Fourier-transform infrared spectroscopy of adsorbed CO revealed that the nickelcontaining samples are comprised of a solid solution of praseodymium, cerium and zirconium oxides with the fluorite structure as well as nickel oxide particles with a size up to 100 nm. All prepared nanocomposite catalysts show a high catalytic activity in the water-gas shift reaction. The optimum content of nickel in the catalyst providing the maximum activity was found to be 10 wt. %. A high oxygen mobility in these catalysts estimated by the temperature-programmed oxygen isotope heteroexchange with C18O2 provides required coking stability. To eliminate local overheating of the catalyst and decrease the pressure drop in the reactor, as required for further up-scaling, the active component was supported on a metal plate made of Ni-Al foam alloy. At a fixed contact time, the same level of CO conversion with a fraction of the active component was achieved with an approximately 50 wt% loading on the support.

The electronic structure of the model alumina-chromium catalyst CrOx/Al2O3 for isobutane isomerization was investigated using the method of steady-state photoluminescence (PL). The chromium content varied in the investigated samples from 0.1 to 11.0 wt % in terms of Cr2O3. The luminescence and luminescence excitation spectra of Cr3+ were recorded under conditions of strong reabsorption. The feasibility of the Cr3+: Al2O3 (α-, γ-Al2O3) polymorphic phase detection and separation of the surface and bulk luminescence was shown. The Cr3+ luminescence and luminescence excitation spectra of the industrial catalyst IM-2201 were recorded.

Supported Cu/ZSM-5 catalysts have been synthesized by ion exchange and impregnation using aqueous ammonia solutions of copper nitrate containing orbital-ordered copper ions. The state of the copper-containing component in the pore space of the catalysts and copper sorption in the catalysts have been investigated by a complex of physicochemical methods. The catalytic properties of Cu/ZSM-5 in the selective catalytic reduction of NO with propane are reported. The catalytic properties depend on the copper precursor structure and deposition method, which determine the size of the copper oxide clusters on the outer surface of zeolite crystals.

The oxidative bromination of C2–C8 alkenes with HBr–NaNO2–O2 in solutions of BMImBr, HMImBr or BMImBF4 containing 16–28 wt% H2O was studied using volumetric method, GC–MS analysis, 14N NMR and UV–VIS spectroscopy. The optimal conditions to conduct the reaction at high selectivity for 1,2-dibromoalkanes in BMImBr were determined. The composition of ionic liquid affects the catalytic performance. Although in BMImBF4 the reaction runs with equal rate as in bromide ionic liquid, the fraction of bromohydrin in the reaction products increases to 20 %. Generated from NaNO2, NOx operated as a catalyst in the oxidation of Br− and was oxidized to catalytically inert NO3 − anions when complete conversion of HBr was attained. Oxidative bromination of alkenes