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A comparison is made of the thermoanalytical characteristics and the composition and structure of solid products of the thermal decomposition of ortho-phthalates [Cu(H2O)2(C8H4O4)], [CuNi(H2O)4(C8H4O4)2], and [Ni(H2O)2(C8H4O4)](H2O)2. It is found that the thermal decomposition of these compounds upon heating to 500°C in a He atmosphere can be conditionally divided into two stages: dehydration and decarboxylation. Polymer conglomerates containing uncoated Cu nanoparticles as large as 75 nm are embedded into the polymer matrix of the composite obtained via the thermal decomposition of [Cu(H2O)2(C8H4O4)]. Three types of nanoparticles with sizes of 40–85, 15–25, and 10–15 nm are embedded in the polymer matrices of composites. The particles are Cux/Ni1−x solid solutions of different compositions, obtained via the thermolysis of [CuNi(H2O)4(C8H4O4)2]. It is found that the onset temperature of [CuNi(H2O)4(C8H4O4)2] decarboxylation at the third part of the second stage with the formation of a three-phase region correlates with the temperature of decomposition of Cux/Ni1 – x solid solutions in the binary metal system, due apparently to the quantum size effect.

The effect of TiCl₄ hydrolysis temperature on the structural, textural and morphological properties of the resulting rutile and on the changes of these properties upon calcination was studied. The XRD, Raman spectroscopy, mercury porosimetry, BET, SEM and TEM studies have revealed that TiO₂ rutile has a hierarchical 3D-architecture. The obtained nanostructured rutile had a cauliflowerlike/ spherical morphology composed of fan-shaped nanofibers. Rutile samples were shown to have a heterogeneous pore structure including micro-, meso- and macropores with a BET surface area of 110-140 m₂/g. According to the mercury porosimetry, among mesopores and macropores the latter dominate in the samples. Elevation of the synthesis temperature from 50-70 to 80-90 °C decreased the fraction of macropores from 95 to 70%. The BET method showed that the samples synthesized at low temperatures (50-70 °C) contain 30-44% of micropores in the total amount of mesopores and micropores. The fraction of micropores decreases to 25-18% with a subsequent increase in the fraction of mesopores as the synthesis temperature is raised to 80-90 °C. As shown by a study of the samples upon calcination in the temperature range of 100-1000 °C, temperature is the key factor that produces changes in the crystallites size, nanofiber length and packing density, and 3D particle shape at different levels of the hierarchical system and determines features of the porous structure and morphological properties of nanostructured rutile. The assessment of photocatalytic activity in the oxidation of acetone vapor demonstrated that, regardless of the hydrolysis temperature, the synthesized samples of nanostructured rutile are able to oxidize acetone vapor to carbon dioxide and water. In the process, activity of the samples is comparable with that of commercial photocatalysts under UV light and is superior to the activity of commercial photocatalysts P25 (2-4 times) and TiO₂ KRONOS vlp 7000 (1.2-2 times) under visible light in dependence on the synthesis temperature.

The processes of phase formation in the Y-Ba-Co-O system doped with scandium are studied in the region of compositions 1:1:4:7. The mechanism of interaction of initial reagents changes with scandium concentration: at low scandium contents, the (Y1−yScy)BaCo4O7+x (R114) doped oxide is formed, similarly to the undoped system, through the YBaCo2O5+x (R112) phase; at significantly higher scandium contents (≥0.2), the role of the intermediate and the competing phase is played by BaCo1−yScyO3−x representing a number of solid solutions which are stable in wide ranges of temperatures and scandium contents. It is shown that scandium in the R114 structure preferably occupies the yttrium position (Y1−yScyBaCo4O7+x), and the maximum degree of substitution is ymax ≈ 0.3–0.35. When yttrium is substituted with a smaller (in terms of ionic radii) scandium atom, the size of the unit cell diminishes nearly isotropically, the maximum change of its volume being 2.0% (from 353.0 A3 to 345.9 A3).

A relationship is established between the structural and thermoanalytical characteristics of the decomposition of hydrogen maleates and phthalates of Fe(II), Co(II), Ni(II), Cu(II). The temperatures of the onset of the first and second stages of decomposition grow in the series of both hydrogen maleates Cu ≤ Fe < Co < Ni and phthalates Fe ≤ Co < Ni < Cu, while the lengths of M– $${{{\text{O}}}_{{{{{\text{H}}}_{2}}{\text{O}}}}}$$ and M–Oanion bonds shrink in these structures. At the third stage, the temperature of the onset of the decarboxylation of hydrogen maleates and phthalates falls in the order Fe > Co > Ni > Cu. The size of metal nanoparticles additionally contained in a polymer or graphene shell grows from 3.5 to 5 nm (Co) and from 4.5 to 7 nm (Ni) upon moving from composites obtained through the decomposition of hydrogen maleates to hydrogen phthalates. Polymeric conglomerates containing shell-less copper nanoparticles, the average size of which ranges from 7.5 to 50 nm, are incorporated into a polymer matrix of composites obtained via the thermolysis of Cu(II) hydrogen maleate and phthalate.

Mn-substituted cordierites, 2(Mg1−xMnx)O·2Al2O3·5SiO2 (x = 0–1), were prepared from natural components (talc, clay, alumina) and MnO2. Sintering behavior, phase transformation, and microstructural features of the samples were investigated using X-ray diffraction (XRD), differential thermal analysis (DTA), dilatometric measurements and scanning electron microscopy (SEM) with energy dispersive analysis (EDS). The results of DTA and XRD analysis indicate that MnO2 is successively reduced to Mn2O3 and MnO in the sintering process. Mn2+ ions incorporate into the crystal structure of α-cordierite substituting Mg2+ ions in octahedral sites and thus increasing the cordierite unit cell volume. Mn promotes the sintering process: the crystallization temperature, melting point, density and open porosity of Mn-substituted cordierites lowered, whereas the shrinkage and medium pore diameter enlarged with an increase in MnO2 content in the mixture of raw materials. Surface enrichment with Mn with the formation of manganese oxide crystallites was found for the samples with high substitution degree.

Mn-containing cordierites 2MnO·2Al2O3·5SiO2 were prepared by mechanochemical method from kaolinic clay, alumina and MnO2 after calcination at 1100°C. Phase composition of prepared samples, their texture properties and catalytic activity in ammonia oxidation reaction were found to depend on the activation time. The mechanochemical treatment of raw materials for 90-180 s gave well-crystallized cordierite ceramic characterized by the surface enrichment with Mn cations and high catalytic activity in ammonia oxidation reaction. The increase activation time to 270-360 s led to the possible interaction of MnO2 with Al-containing components during the mechanochemical treatment to form Mn-Al-spinel which is less selective.

Four different preparation routes were used to synthesize Sr2TiO4 with the structure of layered perovskite: sol-precipitation (SP), co-precipitation (CO), citrate precursor (CT) and mechanochemical (MA) methods with further calcinations at 1100 °C. The XDR, XPS, BET, SEM techniques showed that the different preparation routes caused the formation of layered perovskite phase with different admixture phases, particle sizes and the surface enrichment with layered perovskite (for SP and MA samples) or strontium oxide (for CO and CT samples). The trend of increasing of CH4 conversion and C2-yield in oxidative coupling of methane at 800-900 °C was found to be the following: SP≈MA > CO > CT samples. The C2-yield of the most active catalysts was measured to be about 12%.

Conditions of synthesis are optimized and XRD and thermoanalytical studies are performed for normal maleate [Zn(H2O)2(C4H2O4)] and acid maleate [Zn(H2O)4(C4H3O4)2], along with acid Co(II)–Zn(II), Ni(II)–Zn(II) maleates. It is shown that when solid solutions thermally decompose in acidic maleate systems, the kinetically less stable component causes the temperature of decomposition of the more stable component to fall. It is established that the solid residue of Zn(II) maleate after heating to 500°C in a He atmosphere is a composite containing Zn oxide whose reduction to metal begins at 675°C. The decomposition of [(Co0.1Zn0.9)(H2O)4(С4H3O4)2] leads to the oozing of metallic cobalt atoms embedded in the channels of the ZnO structure that act as a catalyst for the spontaneous growth of uniform carbon nanotubes on the surface of the composite. After thermal decomposition of the samples in a system of acid Ni(II) maleate–acid Zn(II) maleate, only the bimetallic phase is observed in the composites, and there is no zinc oxide.

The physicochemical state of supported platinum and the surface of the support is studied for a number of industrial 0.5 wt % Pt/graphite (freshly prepared, after the synthesis of hydroxylamine sulfate via NO hydrogenation in sulfuric acid, and regenerated) by scanning electron microscopy (SEM), transmission electron microscopy(TEM), X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and CO chemisorption. It is shown that platinum particles agglomerate in a catalyst during operation, and its regeneration results in finer dispersity of the supported metal. Despite the common opinion that a platinum surface is modified by sulfur during the synthesis or regeneration of such catalysts, no evidence of this is found via XPS. Data showing that the surface nitrogen-containing graphite groups formed during the preparation of a catalyst are responsible for the modification of the absorption properties of platinum particles with respect to CO are obtained for the first time. The latter seems to be one of the factors that influence the catalytic properties of platinum in NO hydrogenation.

Silicoaluminophosphate-11 (SAPO-11) crystals were synthesized in different media – water and ethanol – by the two-stage hydrothermal method using ultrasonic pretreatment of precursor mixture. Changing of the synthesis medium from water to ethanol leads to transformation of SAPO-11 morphology: from pseudo-spherical aggregative crystals to novel screw-like morphology. SAPO-11 crystals, synthesized in ethanol medium (Et-SAPO-11), have remarkable textural properties: the greater values of BET surface area and micropore/mesopores volume, compared with crystals, obtained in the water medium (W-SAPO-11). Besides, the acidity of Et-SAPO-11 is lower than that of W-SAPO-11 due to hindered incorporation of silicon into aluminophosphate lattice in ethanol medium.

Extrusion molding, varying the particle size and the conditions for obtaining corundum, was used to obtain ceramic block carriers. The structural and mechanical properties of the molding bodies were investigated, and the textural and strength characteristics of the blocks after calcination were determined. It was shown that the use of corundum powder obtained by mixing particles of different size results in the production of molding bodies of the first or fourth structural-mechanical type and makes it possible to produce ceramic block carrier with channel density about 200 pieces/inch2, mechanical strength at least 4.3 MPa, and high resistance to thermal cycling.

Composite multi-component biocatalysts were prepared by entrapping lysates of a recombinant rE. coli/lip strain producing Thermomyces lanuginosus lipase into composite nanocarbon-containing matrices based on a SiO2 xerogel. The dependence of the lipase activity and operational stability on the type of the carbon component (nanotubes or nanospheres of different diameters) was studied in the bioconversion of triglycerides (hydrolysis and interesterification), as well as in the esterification of saturated fatty acids—namely, butyric (C4:0), capric (C10:0), and stearic (C18:0) acids—with isoamyl alcohol. It was shown that the biocatalytic properties were determined by both the texture parameters of the nanostructured carbon included and the type of enzymatic reaction performed. Biocatalysts without a nanocarbon component had the highest operational stability in the batch process of interesterification of sunflower oil with ethyl acetate; the half-life time was found to be 720 h at 40°C. Biocatalysts containing carbon nanotubes of ~21 nm in diameter were five to six times more active in the batch esterification process than biocatalysts without a nanocarbon component. Biocatalysts containing carbon nanotubes catalyzed the synthesis of esters in a binary organic solvent (hexane and diethyl ether) without a loss of activity for more than 500 h at 40°C.

Regularities of the thermolysis of acidic salts of unsaturated (maleic) [M(H2O)4(C4H3O4)2] and aromatic (ortho-phthalic) [M(H2O)6](C8H5O4)2 (M = Fe(II), Co(II), and Ni(II)) acids are established. The thermolysis of both maleates and phthalates can conventionally be divided into three stages. The onset decomposition temperature of the maleates is insignificantly higher than that of the phthalates for the salts of similar metals. The onset dehydration temperature increases in the series of the acidic transition metal maleates and phthalates Fe Co > Ni. Composites consisting of a metal, an organic polymer, and amorphous carbon are the thermolysis products of both maleates and phthalates in a helium flow. The composites with iron and cobalt in the polymer contain nanosized metal particles and oxide nanoparticles, whose content increases in the composites obtained by the decomposition of phthalates, whereas only metal nanoparticles are observed in the composite with nickel. The compositions and structures of the carbon/polymer matrix differ in these composites.

Synthesis methods of zeolite beta pellets and films with different texture have been developed. Uniform zeolite β nanocrystals were used as initial blocks for building hierarchically porous monoliths, pellets and films. Monoliths and pellets were formed by centrifugation and drying zeolite β suspension, respectively. Films were prepared by drying zeolite β/water/heptane emulsion and zeolite β/water/PDDA mixture followed by calcination and by spin-coating of zeolite β/H 2 O suspensions. The synthesized samples were characterized by dynamic light scattering, X-ray diffraction, X-ray fluorescence spectrometry, scanning and transmission electron microscopy and argon adsorption measurements. Zeolite β nanocrystals are highly crystallized and exhibit high BET surface area (530 m 2 g -1 ), significant external surface area (330 m 2 g -1 ) and high total pore volume (0.73 cm 3 g -1 ).

XRD phase analysis and thermal analysis are used to confirm the formation of a continuous series of solid solutions in which one cation is substituted for another in the systems Co(II) hydrogen maleate–Ni(II) hydrogen maleate; Fe(II) hydrogen maleate–Co(II) hydrogen maleate; and Fe(II) hydrogen maleate–Ni(II) hydrogen maleate. The unit cell volume of these solid solutions is shown to depend linearly on their composition. The linear character of changes in the initial temperatures of dehydration and thermal decomposition is established. Using the example of the first of these systems, it is shown that when heated, bimetallic nanoparticles embedded in the polymeric matrix of composites obtained via the thermal decomposition of solid solutions of hydrogen maleates undergo a second-order phase transition, resulting in decomposition of the solid solutions of metals at the Curie temperature.

The novel macroporous carbon-mineral Sapropel supports were obtained from lacustrine sapropel silts of freshwater lakes by annealing of semi-coke in the inert atmosphere. The specific surface area of these supports varied from 10 to 100 m 2 /g, the total pore volume from 0.3 cm 3 /g till 1.6 cm 3 /g; macropores of diameters more than 2 µm were predominating. The Sapropel supports were studied for the adsorption/adhesion of enzymatic active substances, such as whole bacterial cells, and invertase-active fully destroyed baker's yeast cells (autolysates), and purified enzyme nitrilase. The heterogeneous biocatalysts with required enzymatic activity were prepared and their properties were studied in the corresponding bioconversion processes. The invertase-active biocatalysts exhibited high activity, 120–135 U/g, and stability; the half-times of their inactivation (t ½ ) were more than 1000 h in the continuous process of sucrose hydrolysis at 50 °C. The nitrilase-active biocatalysts for “green” chemistry of nitriles possessed high activity, 350–500 U/g, and the t ½ were estimated to be more than 100 h in the periodic process of hydration of acrylonitrile to acrylic acid at 22 °C.

Nanocarbon-containing mesoporous silica covered with a varying amounts of nanostructured carbon of different morphologies were used as supports to immobilize Thermomyces lanuginosus lipase. The catalytic properties of the prepared biocatalysts were studied in both the transesterification of vegetable (linseed) oil in the presence of ethyl acetate and the esterification of the fatty acid (capric C10:0) in the presence of secondary (isopropyl or isoamyl) alcohols. The physico-chemical characteristics, such as the amount of adsorbed lipase, its specific activity, and the dependence of the activity and stability of the prepared biocatalysts on the support type were evaluated. The Michaelis-Menten kinetics was studied in the esterification of capric acid with isoamyl alcohol. The prepared biocatalysts were shown to retain up to 90% activity for >1000 h in the synthesis of isoamyl caprate. The half-time of the biocatalysts inactivation in the transesterification of linseed oil was found to be more than 700 h at 40°C.

The effect of various admixtures (graphite, sawdust, mullite–silica fiber, vermiculite, boric acid, different size fractions of cordierite, corundum microspheres) in the cordierite stock (mixture of talc, clay, manganese oxide, and aluminum hydroxide) on the formation of Mn-substituted cordierite has been investigated. The admixtures exert an effect on the degree of cordierite formation, on the impurity phase content of the product (including its Mn2O3 content), on the surface concentration of manganese cations, on their oxidation state, on the texture of the catalysts, and on their ammonia oxidation activity. The highest NO x yield is observed with the catalysts containing a coarse fraction of cordierite and corundum microspheres, which are characterized by a high surface concentration of oxidized manganese cations and have large transport pores.

Studies of the thermolysis of ortho-[Ni(H2O)2(C8H4O4)](H2O)2, [Cu(H2O)(C8H4O4)], and acid [M(H2O)6](C8H5O4)2 (M(II) = Fe(II), Co(II), and Ni(II)), [Cu(H2O)2(C8H5O4)2] phthalates reveal that the solid products of their decomposition are composites with nanoparticles embedded in carbon–polymer matrices. Metallic nanoparticles with oxide nanoparticle impurities are detected in iron/cobalt polymer composites, while nickel/copper composites are composed of only metallic particles. It is found that nickel nanoparticles with the diameters of 6–8 nm are covered with disordered graphene layers, while the copperbased composite matrix contains spherical conglomerates (50–200 nm) with numerous spherical Cu particles (5–10 nm).

This work continues a series of our studies on the synthesis of nanostructured carbon (NSC) by the pyrolysis of H2 + C3–C4 alkane mixtures on nickel and cobalt metal catalysts supported on chemically diverse inorganic materials (aluminosilicates, alumina, carbon) having different textural characteristics (mesoporous and macroporous supports) and shapes (granules, foamed materials, and honeycomb monoliths). Here, we consider Ni catalysts supported on granular mesoporous silica (SiO2). It has been elucidated how the yield of synthesized carbon depends on the Ni/SiO2 catalyst preparation method (homogeneous precipitation or impregnation) and on the composition of the impregnating solution, including the molar ratio of its components—nickel nitrate and urea. The morphology of catalytic NSC and Ni distribution in the silica granule have been investigated using a scanning electron microscope with an EDX analyzer. Carbon-containing composite supports (NSC/SiO2) have been employed as adsorbents for immobilizing microbial lipase. The enzymatic activity and stability of the resulting biocatalysts have been estimated in transesterification reactions of vegetable (sunflower and linseed) oils involving methyl or ethyl acetate, esterification, and synthesis of capric acid–isoamyl alcohol esters in nonaqueous media.

Catalysts based on Mn-substituted cordierite 2MnO · 2Al2O3 · 5SiO2 have been synthesized using different manganese oxides (MnO, Mn2O3, and MnO2) at a calcination temperature of 1100°C. The catalysts differ in their physicochemical properties, namely, phase composition (cordierite content and crystallinity), manganese oxide distribution and dispersion, texture, and activity in high-temperature ammonia oxidation. The synthesis involving MnO yields Mn-substituted cordierite with a defective structure, because greater part of the manganese cations is not incorporated in this structure and is encapsulated and the surface contains a small amount of manganese oxides. This catalyst shows the lowest ammonia oxidation activity. The catalysts prepared using Mn2O3 or MnO2 are well-crystallized Mn-substituted cordierite whose surface contains different amounts of manganese oxides differing in their particle size. They ensure a high nitrogen oxides yield in a wide temperature range. The product yield increases with an increasing surface concentration of Mn3+ cations. The highest NO x yield (about 76% at 800–850°C) is observed for the MnO2-based catalyst, whose surface contains the largest amount of manganese oxides.

The evolution of self-sustained reaction-rate oscillations in the catalytic oxidation of propane over a nickel foil has been studied in situ using X-ray photoelectron spectroscopy coupled with online mass spectrometry and gas chromatography. Changes in the effective surface area and in the catalyst morphology under reaction conditions have been examined by scanning electron microscopy and a krypton adsorption technique. It is shown that the regular kinetic oscillations arise under oxygen-lean conditions. CO, CO2, H2, H2O, and propylene are detected as products. The conversion of propane oscillates in a range from 1% to 23%. During the half-periods with high activity, the main reaction pathway is the partial oxi- dation of propane: selectivity toward CO achieves 98%. In contrast, during the half-periods with low activity, the reaction proceeds through three competitive pathways: the partial oxidation of propane, the total oxidation of propane, and the dehydrogenation of propane to propylene. The driving force for the self-sustained kinetic oscillations is the periodic reoxidation of nickel. According to the Ni2p and O1s core-level spectra measured in situ, the high-active catalyst surface is represented by metallic nickel, whereas during the inactive half-periods the catalyst surface is covered with a thick layer of NiO. The intensity of O1s spectra follows the oscillations of O2 in the gas phase during the oxidation of propane. It is found that during the induction period before the regular oscillations appear, a rough and porous structure develops because of strong reconstruction of the catalyst surface. The thickness of the recon- structed layer is approximately 10–20 μm. This process is accompanied with at least an 80-fold increase in the effective surface area compared with a clean, non-treated nickel foil, which undoubtedly leads to a drastic increase in the number of active sites. We believe that it is the main reason for the induction period always being observed before the appearance of self-sustained oscillations in the catalytic oxidation of light hydrocarbons over catalysts with a low specific surface area (single crystals, foils, or wires). Moreover, without such reconstruction, the oscillations cannot arise due to low activity of such catalysts.

The synthesis of nanostructured carbon (NSC) on graphite electrodes with a supported Co catalyst by C3 and C4 alkane pyrolysis in the presence of hydrogen has been investigated. Co(II) hydroxo compounds have been deposited onto graphite, and a Co/graphite catalyst has been prepared by the homogeneous precipitation of divalent cobalt from cobalt nitrate solutions in the presence of urea and compounds containing OH groups, namely, lower alcohols (ethanol, n-propanol, and n-butanol) and polyols (ethylene glycol, glycerol, and sorbitol). The effect of Co catalyst preparation conditions on the pyrolytic activity of the catalyst and on the morphology of the synthesized NSC has been investigated. An active Co/graphite catalyst forms in the presence of an alcohol containing 1-3 OH groups. A fairly uniform NSC layer on the graphite surface is obtained at Co(II) nitrate concentrations of 0.05–0.1 mol/L, a urea concentration of 1 mol/L, and glycerol concentrations of 5–20 vol %. The electrochemical characteristics of the electrodes prepared and those of a microbial fuel cell (MFC) involving an NSC/graphite anode and an activated-sludge microbial consortium have been determined. The maximum power of the MFC under the conditions examined is 4.8 mW per square meter of the anode’s geometric surface area.

Nanocarbon-containing mesoporous silica covered with a varying amounts of nanostructured carbon of different morphologies were used as supports to immobilize Thermomyces lanuginosus lipase. The catalytic properties of the prepared biocatalysts were studied in both the transesterification of vegetable (linseed) oil in the presence of ethyl acetate and the esterification of the fatty acid (capric C10:0) in the presence of secondary (isopropyl or isoamyl) alcohols. The physico-chemical characteristics, such as the amount of adsorbed lipase, its specific activity, and the dependence of the activity and stability of the prepared biocatalysts on the support type were evaluated. The Michaelis-Menten kinetics was studied in the esterification of capric acid with isoamyl alcohol. The prepared biocatalysts were shown to retain up to 90% activity for1000 h in the synthesis of isoamyl caprate. The half-time of the biocatalysts inactivation in the transesterification of linseed oil was found to be more than 700 h at 40°C.

The aluminosilicate microspheres from the fly ash of different power stations (Western Siberian TETs, Belovskaya GRES, Novo-Kemerovo TETs, and Tom-Usinskaya GRES), which burn Kuznetsk coal, were studied by a set of physicochemical methods (BET, SEM, XRD analysis, and granulometric analysis). For comparison, a sample of microspheres from the Pavlodar TETs-2, which burns Ekibastuz coal, was examined. Differences in the textural, structural, and morphological properties of microspheres, which are related to the nature of burnt coal and the operating conditions of combustion, were demonstrated.

Metal electrodeposition has recently attracted renewed interest in the context of the design of tailored nanomaterials for various applications, such as, for example, fuel cells and sensors. This work is devoted to the investigation of the kinetics of potential-controlled deposition of Pt, at low (below 10 μg cm −2 ) metal loadings, on non-porous carbon supports (glassy carbon and highly oriented pyrolytic graphite), from Pt (II) and Pt (IV) precursor complexes, and the structure and the morphology of the ensuing deposits. Comparison of the data of this work with the results of our earlier study [L.M. Plyasova, I.Yu. Molina, A.N. Gavrilov, S.V. Cherepanova, O.V. Cherstiouk, N.A. Rudina, E.R. Savinova, G.A. Tsirlina, Electrochim. Acta 51 (2006) 4477], where much higher metal loadings were produced, confirms the scalability of the microstructure with the thickness of deposits, the electrode potential being the key factor defining the geometry, the mutual orientation and the degree of coalescence of Pt nano-crystals.

Comparison was made for the structural, IR spectral, and thermoanalytical characteristics of normal [M1(H2O)2(C4H2O4)](H2O) (M1 = Co(II) and Ni(II)) and acid maleates [M2(H2O)4(C4H3O4)2] (M2 = Mn(II), Fe(II), Co(II) and Ni(II)). Only structures of acid maleates contain intramolecular asymmetric hydrogen bond whose asymmetry increases in the series of transition metal salts. Thermal decomposition of Co(II), Ni(II) normal maleates, and Mn(II), Fe(II), Co(II), Ni(II) acid maleates proceeds in three stages. Onset decomposition temperatures for the first and second stages decreases in the series of normal maleates Co(II) ≥ Ni(II) and increases in the series of acid maleates Fe(II) Ni(II) and acid maleates Mn(II) > Fe(II) > Co(II) > Ni(II).

Arrays of vertically aligned carbon nanotubes (CNTs) grown on n -doped silicon substrates using an aerosol-assisted catalytic chemical vapor deposition (CCVD) technique have been tested as supercapacitor electrodes. Electrochemical properties of the electrodes were shown to be significantly dependent on the array thickness. At scan rate of 20 mV/s the largest specific capacitance of 124 F/g was achieved for the ∼280–μm array, while increase in the thickness to ∼ 1100 μm caused a drop in electrode capacitance by four times. It was shown that in a sulfuric acid electrolyte, the redox processes with iron nanoparticles encapsulated in CNTs contribute significantly to the capacitance of array. From the Mossbauer spectroscopy, these nanoparticles are present as α-Fe, γ-Fe, and Fe 3 C phases. X-ray photoelectron spectroscopy revealed that during the electrode charging and discharging sulfates of Fe(II) and Fe(III) are formed in surficial layers of the nanoparticles.

Electrocatalytic activity for the oxygen reduction reaction (ORR) of the carbon-supported Pt catalysts obtained by chemical and electrochemical deposition has been studied in 0.10 M HClO 4 at 293 K in the expectation to gain new insights into the influence of the substructure of platinum on its catalytic properties for the ORR. Electron microscopy, XRD and electrochemical techniques have been employed to demonstrate that: (i) the ‘chemically’ synthesised Pt/C catalysts contain highly-dispersed isolated metal particles at intermediate metal loadings and both isolated crystallites and crystallite aggregates at higher loading; (ii) the electrodeposited Pt/C materials are ‘nanostructured’, i.e. contain large (up to ca 350 nm) aggregates with the deposition potential dependent morphology composed of comparatively small ( 2 , which further reduction occurs at the highly catalytically active Pt(1 1 1) facets. Structural defects present at an optimal concentration are concluded to promote the ORR catalytic activity of platinum, but excessive defectiveness of the Pt catalyst might hinder the kinetics of the oxygen electroreduction.

A procedure has been proposed for the preparation of copper/polymer composites through Cu(C4H4O4) · H2O succinate thermolysis. Three types of copper nanoparticles have been incorporated into a fibrous carbon-polymer matrix of the composite: cubic (350 × 350 nm) and needle-like (40–80 nm in diameter and 4.5–5.5 μm in length) crystals and spherical copper particles (5 to 45 nm). We have compared copper succinate and copper maleate decomposition processes. The composites obtained through thermolysis have been shown to differ drastically.

Four types of iron containing materials have been synthesized: conventional zeolite Fe-ZSM-5 (conv), hierarchical zeolite Fe-ZSM-5 (hier), small crystals (d = 330 nm) of zeolite Fe-ZSM-5 (nano) and ferric oxide species supported on the amorphous silica Fe/SiO2. Samples were prepared by hydrothermal treatment, polystyrene spheres were used as a template for Fe-ZSM-5 (hier) and Fe/SiO2. The materials were characterized by different techniques. Nature of iron-containing particles in the samples and stability of iron species in the reaction media were suggested by using thermodynamic considerations. All solid-phase Fe-containing samples as well as dissolved Fe(NO3)3 were tested in H2O2 decomposition reactions in absence or presence of iron-complexing agent Na2EDTA, which has been used to test the catalyst stability. Catalytic activity of ferric species in hydrogen peroxide decomposition for small 330-nm crystals of Fe-ZSM-5 was 1.4 times higher than for large zeolite crystals, and significant decrease of the activity was observed for samples containing amorphous silica phase. Experimental results showed that ferric sites in zeolite were stable due to the limited diffusion of Na2EDTA in zeolite phase. Wet hydrogen peroxide oxidation of organic complexing agents by H2O2 using Fe-containing zeolites has a good potential for purification of nuclear waste water.

Hierarchically porous zeolite materials built of closely and randomly packed uniform Fe–silicalite nanobeads were synthesized. The desired assembly of nanobeads was achieved by the centrifugation and sedimentation of nanozeolite suspension followed by drying and calcination. A micro/meso/macroporous Fe–silicalite material with spongy texture built of closely packed nanocrystals was designed using polystyrene latex as a supramolecular template. Large Fe–silicalite microbeads were synthesized to compare their structure with the nanocrystalline materials. The synthesized samples were characterized by laser diffraction analysis, X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, argon and nitrogen adsorption measurements, inductively coupled plasma optical emission spectrometry, UV visible diffuse reflectance spectroscopy and temperature-programmed desorption of ammonia. Fe–silicalite nanozeolite materials have shown high crystallinity, and possess micro- and meso/macropore surface areas and high specific pore volumes. Pellets built of closely packed nanocrystals have exhibited good mechanical stability in benzene and water. Calcined Fe–silicalite materials built of nanobeads were observed to contain highly dispersed ferric clusters no more than 1 nm in size. The 3 nm ferric clusters in the zeolitic microbeads resulted in the appearance of Lewis acid sites with medium strength, which are absent in the nanobeads. Catalytic performance of hierarchically porous Fe–silicalites was studied in the total oxidation of clarithromycin lactobionate by H2O2 at 323 K compared with Fe–silicalite microbeads. Hierarchical Fe–silicalites are more efficient catalysts vs. Fe–silicalite microbeads due to increased catalytic site accessibility.

The multi-component heterogeneous biocatalysts were prepared by entrapment of whole cells or cells’ lysates of a recombinant strain Escherichia coli producing of thermostable lipase from Thermomyces lanuginosus (r E.coli /lip) inside silica xerogel and nanocarbon-in-silica composites. The properties of intracellular recombinant lipase and the prepared heterogeneous biocatalysts, such as enzymatic activity and stability, were studied in periodic process of triglycerides’ hydrolysis and interesterification. The thermal stability of recombinant lipase was studied by the heating bacteria r E.coli /lip in a buffer and olive oil at 60–100 °C. The effects of nanocarbons included inside SiO 2 -xerogel, such as multi-walled carbon nanotubes with different diameters and dispersity, and “nano-onion”, on the properties of multi-component biocatalysts were investigated. The {nanocarbon-in-silica} biocatalysts prepared by entrapping cells’ lysates of r E.coli /lip together with aggregated “thick” nanotubes (20–22 nm in diameter) were found to possess the highest hydrolytic activity close to 1000 LU/g. The activity of composite biocatalysts containing cells’ lysates of r E.coli /lip and dispersed “thin” nanotubes (9–11 nm in diameter) did not exceed 400 LU/g. The similar effect of nanocarbons’ inclusion inside multi-component biocatalysts on the activities of entrapped whole cells, cells’ lysates and purified recombinant lipase was revealed.

Comparative studies of nanocarbons and nanocarbon-in-silica adsorbents for the immobilization of enzymes, for example, thermostable lipase from Thermomyces lanuginosus, were performed. Carbon nanotubes (CNTs) with different diameters, specific surface areas, and concentrations of surface carboxy groups were studied as the nanocarbon adsorbents. The nanocarbon-in-silica adsorbents were prepared by the synthesis of carbon nanofibers (CNFs) in SiO2 xerogel in the course of the pyrolysis of C3-C4 alkanes on Ni catalysts; their physicochemical and textural characteristics were studied by thermal analysis, scanning electron microscopy, and nitrogen porosimetry. It was found that carbon nanofibers of different diameters were synthesized in the bulk of a silica matrix only at Ni contents higher than 1–1.5%. The CNFs-in-silica supports were nanoporous: the mean pore diameter and the specific surface area were ∼10 nm and 250–300 m2/g, respectively. The heterogeneous biocatalysts prepared by the adsorption of thermostable lipase on the CNTs and CNFs-in-silica supports were investigated in the reaction of triglyceride (tributyrine) hydrolysis; the physicochemical properties of biocatalysts and their enzymatic activity and stability were studied depending on the hydrophobicity-hydrophilicity of the support/matrix.

Zeolite h-FeZSM-5 with a hierarchical micro/macropore system has been synthesized in the presence of a template based on the close-packed polystyrene (PS) spheres, and the conventional zeolite FeZSM-5 has been obtained in the absence of a PS template. The zeolites have been characterized by X-ray diffraction, scanning and high-resolution transmission electron microscopy, and N2 sorption. The macropore walls of the hierarchical zeolite consist of ZSM-5 nanocrystals and amorphous globules of silica. Compared to the conventional zeolite, the hierarchical one has a high BET and external surface areas of 245 and 472 m2/g, respectively, and a high pore volume of 0.6 cm3/g. The catalytic properties of the Fe-containing zeolites were studied in the H2O2 decomposition reaction in the absence and in the presence of EDTA ligands and in the oxidation of low- and high-molecular-weight organic compounds by hydrogen peroxide at 25°C. Hierarchical zeolite h-FeZSM-5 is highly efficient in the oxidation of large molecules.

Metal-polymer composites have been prepared through the thermolysis of the [M1(H2O)2(C4H2O4)] · H2O (M1 = Co(II), Ni(II)) neutral maleates and [M2(H2O)4(C4H3O4)2] (M2 = Fe(II), Co(II), Ni(II)) acid maleates. In the polymer matrix of the Fe-containing composite, we identified metal, Fe2O3, and Fe3O4 particles, with slight densification of the matrix around them. The polymer matrix of the cobalt maleate-derived composite contained four types of nanoparticles: α-Co, β-Co, and CoO in polymer shells and Co3O4 with no polymer shell. The decomposition of the nickel maleates yielded homogeneous nickel nanoparticles (4–5 nm) covered with two to five graphene layers. The Co-containing composite was found to be a dielectric. The Ni-containing composite exhibited variable range hopping conduction in the range T ≤ 50 K.

The thermal decomposition of neutral ([Cu(H2O)(C4H2O4)]) and acidic ([Cu(H2O)4](C4H3O4)2) maleates can conventionally be divided into four stages: (1) dehydration, (2) polymerization, (3) isomerization of the maleate ion to the trans form with the simultaneous reduction Cu(II) → Cu(I), and (4) decarboxylation of copper(I) fumarate. The third and fourth stages of the decomposition of these salts coincide. The residue after the thermolysis of copper(II) maleates in a He flow is a composite consisting of aggregates from 50 nm to several microns in size. Spherical conglomerates (50–200 nm) containing many spherical Cu particles (5–10 nm) are incorporated into the organic polymer matrix of these aggregates.

Series of hierarchical zeolites ZSM-5 and FeZSM-5 were prepared by hydrothermal treatment using polystyrene spheres template and characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy, scanning and high-resolution transmission electron microscopies, and N2 sorption techniques. Walls of the macroporous structure consisted of ZSM-5 nanocrystals with a size of 20–300 nm and amorphous globules of SiO2. Hierarchical FeZSM-5 contained iron in the form of iron oxide particles with a size of 2–3 nm. Hierarchical zeolites had high values of surface area (437–613 m2/g), external surface area (131–462 m2/g), and pore volume (0.36–0.76 cm3/g). Iron-containing zeolites were tested in the H2O2 decomposition reactions in the absence and presence of iron-complexing agent, as well as in oxidation of low and high molecular weight organic compounds by H2O2 at 25 °C and compared with homogeneous Fe(NO3)3 solution. Hierarchy of the zeolite porosity resulted in a significant improvement of the catalyst properties.

Composite materials containing multi-walled carbon nanotubes (MWNT) in polyolefine (polyethylene and polypropylene) matrix were prepared by coagulation precipitation. The morphology and structure of produced composites was investigated by scanning and transmission electron microscopy. Thermal analysis (oxidation in air) was performed for composites in temperature range 20–500°C. It was shown that the addition of MWNT increases the thermal stability of composites. Electrophysical properties of MWNT/PSt composites were investigated using a four-probe technique. Observed electrical percolation threshold of composite materials is near to 3–3.5wt%. Electromagnetic (EM) response of prepared materials was investigated in broadband region (26–37 GHz and 250–500 GHz). It was found that the EM response of MWNT/polyolefine depends on their electrophysical properties with percolation threshold near 2–3wt%.

A comparative study of multi-component heterogeneous biocatalysts prepared by immuring enzymatic active substances inside the {nanocarbons-in-silica} composites was carried out. Carbonic materials such as nanotubes, nanofibers, and onion-like nanocarbon were examined for inclusion inside SiO 2 -based biocatalysts. The properties of the biocatalysts prepared, such as enzyme activity and stability, were studied depending on the content, physicochemical properties and nanostructure of the nanocarbons included. The biomasses of recombinant strain-producer of glucose isomerase Escherichia coli (rec- E.coli ) and of baker's yeast autolysates were used for biocatalysts’ preparing. The direct correlation between magnitude of increase of biocatalysts’ steady-state activity and efficiency of adsorption/adhesion of enzymatic active substances (enzyme/cell compartments) on nanocarbons was observed. In the case of weak adsorption of glucose isomerase on carbonic materials, the steady-state activity increased by a factor of 1.5 for the catalysts prepared by immuring rec- E.coli inside the {nanorarbons-in-silica) composites and “dry” cross-linking by glutaric dialdehyde (

Comparative studies have been carried out on the preparation of carbon-silica composite matrices for heterogeneous biocatalysts with glucose isomerase activity. Carbon nanotubes and nanofibers have been included inside SiO2 xerogel. The enzymatic activity and operating stability of the biocatalysts have been investigated. Bacterial cells of a recombinant glucose isomerase producer strain have been used as the enzymatically active component of the biocatalysts. The steady-state activity of the biocatalysts subjected to “dry” cross linking with a glutaraldehyde solution (0.1–1%) is 1.5 times higher than the activity of the biocatalysts containing no nanocarbon. The initial and steady-state glucose-isomerase activities of the biocatalysts at 70°C are ∼520–540 and ∼150–160 μmol min−1 g−1, respectively. The half-inactivation time of the biocatalysts under continuous monosaccharide (glucose, fructose) isomerization conditions is up to ∼1500 h.

To study the effect of nanoscale titanium dioxide (TiO2) on cell responses, we synthesized four modifications of the TiO2(amorphous, anatase, brookite, and rutile) capable of keeping their physicochemical characteristics in a cell culture medium. The modifications of nanoscale TiO2were obtained by hydrolysis of TiCl4and Ti(i-OC3H7)4(TIP) upon variation of the synthesis conditions; their textural, morphological, structural, and dispersion characteristics were examined by a set of physicochemical methods: XRD, BET, SAXS, DLS, AFM, SEM, and HR-TEM. The effect of synthesis conditions (nature of precursor, pH, temperature, and addition of a complexing agent) on the structural-dispersion properties of TiO2nanoparticles was studied. The hydrolysis methods providing the preparation of amorphous, anatase, brookite, and rutile modifications of TiO2nanoparticles 3–5 nm in size were selected. Examination of different forms of TiO2nanoparticles interaction with MDCK cells by transmission electron microscopy of ultrathin sections revealed different cell responses after treatment with different crystalline modifications and amorphous form of TiO2. The obtained results allowed us to conclude that direct contact of the nanoparticles with cell plasma membrane is the primary and critical step of their interaction and defines a subsequent response of the cell.

The carbon-carbon composite materials obtained via the synthesis of catalytic filamentous carbon (CFC) on a Ni/graphite supported catalyst in the process of the pyrolysis of C3–C4 alkanes in the presence of hydrogen were systematically studied. The effects of the following conditions on the catalytic activity expressed as the yield of carbon (g CFC)/(g Ni) and on the character of CFC synthesis on graphite rods were studied: procedures for supporting Ni(II) compounds (impregnation and homogeneous precipitation), the concentrations of impregnating compouds (nickel nitrate, urea, and ethyl alcohol) in solution, graphite treatment (oxidation) conditions before supporting Ni(II) compounds, and the pyrolysis temperature of C3–C4 alkanes in the range of 400–600°C. Optimum conditions for preparing CFC/graphite composite materials, which are promising for use as electrodes in microbial fuel cells (MFCs), were chosen. The electrochemical characteristics of an MFC designed with the use of a CFC/graphite electrode (anode) and Gluconobacter oxydans glycerol-oxidizing bacteria were studied. The morphology of the surfaces of graphite, synthesized CFC, and also bacterial cells adhered to the anode was studied by scanning electron microscopy.

Impregnation techniques for corundum (S BET = 0.5 m2/g) as a support for Ni catalysts for C3–C4 alkane pyrolysis into catalytic filamentous carbon (CFC) are compared. The effects of the following factors on the uniformity of the active component (Ni) deposition on the inert support and on the CFC yield (g CFC)/(g Ni) are reported: (1) pH of the nickel nitrate solution, (2) presence of aluminum(III) nitrate in the solution, (3) addition of viscosifying agents (glycerol, glucose, sucrose) to the solution, (4) catalyst calcination conditions before pyrolysis, and (5) catalyst drying technique. The surface morphology of the Ni catalysts and of the carbon deposits resulting from the catalytic pyrolysis of C3–C4 alkanes in the presence of hydrogen has been investigated by scanning electron microscopy. The optimum way of preparing the supported Ni catalysts is by carrying out the incipient wetness impregnation of corundum with a nickel nitrate solution (0.05–0.1 mol/l) containing glycerol (20–25 vol %), drying the product in a microwave oven, and burning away the glycerol before alkane pyrolysis.

Comparative studies of the effect of the physicochemical characteristics of a support (aluminum oxide) on the formation of a supported Co catalyst and its activity in the pyrolysis of alkanes (propane-butane) were performed. The effect of the crystalline modification of alumina on the yield of catalytic filamentous carbon (CFC) ((g CFC)/(g Co)) was studied. The surface morphologies of Co-containing catalysts and synthesized carbon deposits were studied by scanning electron microscopy. It was found that carbon deposits with a well-defined nanofiber structure were synthesized by the pyrolysis of a propane-butane mixture in the presence of hydrogen at 600°C on supported Co catalysts prepared by homogeneous precipitation on macroporous corundum (α-Al2O3). The yield of CFC was no higher than 4 (g CFC)/(g Co). On the Co catalyst prepared by homogeneous precipitation on mesoporous Al2O3, the intense carbonization of the initial support; the formation of cobalt aluminates; and, as a consequence, the deactivation of Co0 as a catalyst of FC synthesis occurred. The dependence of the yield of CFC on the preheating temperature (from 200 to 800°C) of Co catalysts before pyrolysis was studied. It was found that, as the preheating temperature of supported Co/Al2O3 catalysts was increased, the amount of synthesized carbon, including CFC, decreased because of Co0 deactivation due to the interaction with the support and coke formation.

The effects of iron oxide (10%), bismuth oxide (2.2%), and vanadium oxide (1.6%) admixtures on the physicochemical properties of cordierite ceramics are reported, including the phase composition, surface features, porous structure, and activity in ammonia oxidation. The formation of the cordierite phase is favored by introducing the oxide modifiers, by raising the heat treatment temperature, and by extending the heating time. The introduction of V2O5 affords well-crystallized cordierite with a small specific surface area and a large proportion of macropores. The oxide modifiers markedly enhance the ammonia oxidation activity and nitrogen oxide selectivity of the cordierite ceramics.

A comparative study of the synthesis of carbon layers, including catalytic filamentous carbon, on the surface of various alumina modifications was made. The synthesis was performed by the pyrolysis of alkanes (a propane-butane mixture) on Co/Al2O3 supported catalysts. The texture characteristics (specific surface area and pore structure) of the starting supports and adsorbents with a synthesized carbon layer were studied. The surface morphology of Co/Al2O3 catalysts and the synthesized carbon deposits was studied by scanning electron microscopy. It was found that carbon nanofibers were formed only on the catalysts prepared by the homogeneous precipitation of Co compounds onto the surface of macroporous α-Al2O3, whereas carbon deposits on mesoporous aluminum oxides did not exhibit a pronounced fibrous structure. The applicability of C/Co/Al2O3 carbon-containing adsorbents to the immobilization of the nitrile hydratase enzyme and the preparation of a biocatalyst for acrylonitrile hydration to acrylamide was considered.