Nanocomposite materials based on palladium, copper(I) oxide, and magnetite nanoparticles embedded in a nanocellulose matrix by precipitation and coprecipitation methods were obtained in situ and ex situ from solutions of the salts of the corresponding metals. Studies of the characteristics of the resulting composites using Fourier transform IR spectroscopy, X-ray diffraction, SEM, and TEM showed that the encapsulated nanoparticles have an insignificant effect on the morphology and structure of nanofibrillar cellulose. The catalytic properties of the nanocomposites were tested in the hydrogenation of nitrobenzene.

The paper proposes a method for synthesizing a heterogeneous catalyst that contains single Pd sites on γ-Al 2 O 3 surface. This method involves preliminary heterogenization of a Pd complex with a hydroxyquinone (e.g., alizarin) on the γ-Al 2 O 3 surface, followed by hydrogenolysis of the Pd–alizarin bond, reduction of Pd(II) into Pd(0), and removal of alizarin. The catalyst was examined by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and tested in propane oxidation into key petrochemicals. During the test, the catalyst exhibited high activity (242 mol of the product per g-at Pd per hour).

This study investigated the effects of ionol (2,6-di- tert -butyl-4-methylphenol) and CCl 4 as inhibitors of radical reactions in propane oxidation with oxygen in the presence of co-reductants. These compounds inhibit the activity of a Pd/C–FeSO 4 –H 2 catalytic system. Homogeneous catalytic systems based on Pd or Rh compounds, cocatalysts, and co-reductants promote molecular mechanisms for the reaction. The only exception is a Pd(α,α-bipy)Cl 2 –FeSO 4 –CO system, in which both ionol and CCl 4 act as inhibitors.

Heterogenized catalysts were prepared by the immobilization of the homogeneous catalytic systems containing the rhodium complexes, copper compounds, and perfluoroorganic acids onto porous carriers. The activity of the catalysts was studied in the processes of CO oxidation and co-oxidation of CO and propane. The state of the catalyst components was determined and the possibility of their interaction was evaluated by X-ray spectroscopy (XANES and EXAFS) and electrospray mass spectrometry (ESI-MS). The oxidation of CO on the RhCl3-CuCl2-C3F7COOH/γ-Al2O3 catalyst in a flow reactor at 70–80 °C and atmospheric pressure occurs in an oscillating mode. The co-oxidation of propane and CO at 80–95 °C and a pressure of 1.0–1.5 MPa is basically possible but occurs with a low yield of propane oxygenates.

Variation of the nature of the components of the catalytic systems comprising a catalyst [Pd/C, Pd(α,α-bipy)Cl2, RhCl3] and a cocatalyst (FeSO4, CuSO4), as well as a coreductant (H2, CO), allows exerting some control over the selectivity of the process of propane oxidation with oxygen. In particular, the yield of carbonyl compounds such as acetone and propanal in the presence of the Pd/C–FeSO4–H2catalytic system reached 90%, and that of propyl esters in the presence of RhCl3–CuSO4–CO catalytic system was 64.5%. These differences are supposedly attributable to the changes in the process mechanism depending on the composition of the catalytic systems.

The effect of copper compounds and phosphorus–molybdenum–vanadium heteropoly acids (HPAs) H5PMo10V2O40 and H7PMo8V4O40 used as cocatalysts in the cooxidation of propane and CO in the presence of rhodium, palladium, and platinum compounds in an aqueous AcOH medium has been studied. It has been shown that these HPAs are fairly effective; however, in catalyst systems with rhodium and palladium compounds, these HPAs are inferior to Cu(I,II). The inner-sphere and outer-sphere reaction mechanisms have been studied as the most probable oxidation mechanisms; the contribution of each of the mechanisms to the overall process has been determined.

The best examples of catalysts and catalytic systems for the oxidative functionalization of alkanes and mechanisms of their action are considered. The prospects for industrial application of homogeneous catalysis in the synthesis of key petrochemical products, diff erent oxygenated organic compounds based on natural and associated petroleum gases, are outlined. Special attention is given to transformations of methane.

Nanocomposites of different concentrations of cadmium sulfide nanoparticles in a polyacrylamide shell were obtained as a result of the reaction of cadmium nitrate with acrylamide and a tiosulfiding agent (thiourea) in certain stoichiometric ratios followed by thermal polymerization of the reaction mixture. The samples were studied by the methods of elemental analysis, X-ray diffraction, scanning electron microscopy, and optical and luminescent spectroscopy. The sizes of sulfide nanoparticles as well as their distribution in the polymer were determined. It was shown that the absorption spectra have characteristic features of the spectra of composite systems with nanosized semiconductor crystals that manifested "defective" luminescence with a maximum in the 550-570 nm region.

The present paper reports the study of modulation in intensity of light transmitted through the thin films of nanostructured yttria stabilized zirconia (YSZ) with the exposure of moisture at room temperature. For this purpose the precursor of YSZ was prepared and used for the deposition of multilayered thin films on borosilicate substrates. The film was then investigated using SEM, XRD and UV-vis absorption techniques. The refractive index of the sensing material was found as 1.448829. SEM showed the macroporous nature of the film and XRD revealed the minimum crystallite size as 5 nm which was further confirmed using TEM and Zeta nanosizer. Energy band-gaps of one-, two-, three- and four- layered films were estimated as 3.927, 3.919, 3.873 and 3.830 eV respectively by UV-vis spectrophotometer. These films were employed as transmission based opto-electronic humidity sensor. Maximum sensitivity was found as similar to 1.937, 1.642, 1.393 and 1.143 mu W/%RH for one, two, three and four- layered films, respectively. Response and recovery times of the sensor were found as 28 s and 30 s respectively. Experiments were repeated time to time and found that the sensor was similar to 94% stable after long run. Thus the investigated opto-electronic sensor has excellent potential to replace an electrical humidity sensor. (C) 2016 Elsevier B.V. All rights reserved.

The controlled thermolysis of mono(Ni-II, Cu-II, and Co-II) and dinuclear (Ni-II, Cu-II, and Fe-II) chelate complexes with azomethine ligands, containing oxygen, nitrogen, and sulfur atoms in the chelate rings, was studied. The effect of the ligand environment on the thermal stability and composition of the resulting nanocomposites was examined. Comparative thermal analysis (DSC, DTA, and TGA) of the metal chelate complexes was performed. Their thermolysis products were characterized using elemental analysis, X-ray powder diffraction, scanning electron microscopy, and gel permeation chromatography. The magnetic properties of the nanocomposites obtained were analyzed.

We elaborated a method for frontal polymerization of a Rh-containing monomer in the presence of a conventional support to obtain polymer-immobilized hydrogenation catalysts. A hybrid nanocomposite forms during the propagation of a narrow molten zone (first-order phase transition) and is characterized by stable front propagation throughout the reaction volume. The products were characterized by various physicochemical methods and were tested as catalysts in the hydrogenation of cyclohexene, allyl alcohol, and nitrobenzene. The transformation of the X-ray photoelectron spectrum (XPS) on passing from the starting rhodium nitrate complex to its metal monomer (acrylamide complex), polymer, and supported catalyst is described. Native intermediate products were isolated and characterized by XPS.

A comparative analysis of methods used for obtaining hybrid functional materials based on magnetite nanoparticles and humic acids by in situ chemical co-deposition or mechanochemical dispersion showed that the method of in situ chemical co-deposition is optimal for producing Fe3O4−HA nanocomposites with reproducible sizes and structure. The possibility of regulating the sizes and magnetic properties of magnetite nanoparticles by varying the Fe3O4 and HAs ratio in the composite is demonstrated. The mechanochemical synthesis method provided opposite results in terms of decrease and increase of particle sizes, which varied in a broad range from nanoscale to micrometer sizes depending on synthesis conditions, accompanied by their increased size distribution. X-ray phase and Mossbauer studies of the hybrid material samples produced by mechanochemical synthesis showed parameters not typical of the magnetite phase.

A new approach has been proposed for producing nanocomposite gas-sensing materials: in situ preparation of a polymer matrix and metal sulfide or oxide nanoparticles through the frontal polymerization of Co(II), Cd(II), Zn(II) and Pb(II) acrylamide complexes. The composition and structure of the nanocomposites thus obtained have been determined using X-ray diffraction, scanning and transmission electron microscopy, and Raman spectroscopy. The nanocomposites have been tested as room-temperature liquefied petroleum gas sensors.

We present a facile method for the preparation of bimetallic AuAg nanoparticles (NPs) with controlled size and composition rendering them ideally suitable for optical and catalytic applications. In analogy to methods for the generation of monometallic Au and Ag NPs, AuAg NPs were prepared inside polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block-copolymer micelles formed in toluene, by loading the P4VP cores of the micelles first with AgNO(3) and then with HAuCl(4). In contrast to the reverse sequence of loading, homogenously bimetallic AuAg particle arrays were achieved after reduction carried out in solution with hydrazine monohydrate as the reducing agent. TEM reveals that stable and spherical NPs can be prepared well separated from one another and with a narrow size distribution with diameters of ∼3 nm. The bimetallic NP composition was confirmed by energy-dispersive X-ray spectroscopy (EDX) of single NPs. The atomic ratio of Ag and Au contained in single particles is in good agreement with the relative concentrations of both metals used in the synthesis which was confirmed by atomic absorption spectroscopy. The atomic ratio Au : Ag was systematically varied between 3 : 1 and 1 : 3. For all ratios UV-vis spectra showed a single plasmon band. Its wavelength varied from 430 for Au : Ag = 1 : 3 to 515 nm for Au : Ag = 3 : 1, showing a linear dependence on the relative amount of gold within the range of plasmon wavelengths from monometallic gold (538 nm) to silver (415 nm).

Metallopolymers based on unsaturated alkoxides of refractory metals (Ti(IV), V(V), Ta(V), Nb(V)) are synthesized and characterized; their thermal behavior is studied via TGA, TMA, and DSC. It is shown that nanocomposite materials can be synthesized through the polymerization of metal-containing monomers and subsequent controlled thermolysis of the products.

Разработан новый подход к синтезу иммобилизованных катализаторов смешанного типа – фронтальная полимеризация металлосодержащего мономера в присутствии высокодиспергированного минерального носителя. Синтез акриламидного комплекса нитрата Pd(II) на поверхности SiO2, Al2O3 или C, его последующая полимеризация и восстановление приводят к формированию органо-неорганического композита, включающего наноразмерные частицы Pd, стабилизированные полимерной матрицей, и неорганический носитель. Получаемые гибридные нанокомпозиты являются эффективными и селективными катализаторами реакций гидрирования циклогексена, а также алкеновых и ацетиленовых спиртов.

Получены и охарактеризованы металлополимеры на основе непредельных алкоксидов тугоплавких металлов (Ti(IV), V(V), Ta(V), Nb(V)); методами ТГА, ТМА и ДСК изучено их термическое поведение. Показано, что в ходе полимеризации металлосодержащих мономеров и последующего контролируемого термолиза формирующихся продуктов могут быть синтезированы нанокомпозитные материалы.

Сочетанием полимеризации металлосодержащих мономеров в твердой фазе и последующего контролируемого термолиза формирующихся металлополимеров получены металлополимерные нанокомпозиты, представляющие собой наночастицы металлов и (или) их оксидов и карбидов, равномерно распределенные в стабилизирующей их полимерной матрице. Методами рентгеновской дифракции, электронной микроскопии, ферромагнитного резонанса и ИК-спектроскопии показано, что наночастицы в такой системе имеют характерную структуру “ядро–оболочка”, которая включает в себя металлосодержащее ядро и поверхностный слой – полимерную оболочку; оценены параметры этих компонентов.