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Journal of Thermal Analysis and Calorimetry
Authors: V. Sydorchuk, S. Khalameida, J. Skubiszewska-Zięba, and R. Leboda

Abstract

Compositions based on oxides and containing 5–20% w/w of ammonium molybdophosphate have been synthesized by means of different routes. Prepared samples have been studied using nitrogen adsorption–desorption, XRD, DTA–TG, and FTIR spectroscopy. Keggin structure is retained at incorporation of ammonium molybdophosphate into siliceous framework or its deposition on oxide surface and duration following calcinations up to 500 °C. Compositions possess porous structure from micromesoporous to mesomacroporous depending on the preparation method.

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Abstract  

In this article, mechanochemical synthesis of barium titanate from different raw materials was studied. The prepared nanodispersed powders were investigated by means of XRD, DTA-TG, DSC, FTIR, Raman, UV–VIS, ESR spectroscopy, and low-temperature adsorption of nitrogen. Barium titanate possessing high specific surface area was produced directly during dry milling from the mixtures of barium oxides and titanium dioxide low-temperature forms (amorphous and anatase).

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Abstract  

Mechanochemical treatment (MChT) in various media (water, air, ethanol) of the V2O5/ammonium dimolybdate composition at the ratio V:Mo = 0.7:0.3 has been carried out. Physicochemical transformations in this system have been studied by means of X-ray powder diffraction (XRD) and thermal analysis as well as FTIR spectroscopy. Ammonium dimolybdate undergoes hydration with formation of 4-aqueous ammonium paramolybdate during the MChT in water. Changes of phase and chemical composition at activation are determined first of all by nature of medium in which milling was carried out. Maximal interaction of components occurs during modification of the studied system in water.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Sydorchuk, O. Makota, S. Khalameida, L. Bulgakova, J. Skubiszewska-Zięba, R. Leboda, and V. Zazhigalov

Abstract

The deposition of molybdenum and vanadium oxides onto fumed silica, titania, and alumina as supports through dry milling has been carried out. The structure of prepared compositions has been investigated by means of XRD, DTA–TG, FTIR, and UV–Vis spectroscopy, nitrogen adsorption. The deposited crystal phases are sufficiently uniformly distributed on support surface. The supported oxides are subjected to dispersion in process of milling to the state of oligomeric or isolated species. Milled bulk and deposited MoO3 (first of all, on alumina) possesses improved catalytic performance in process of epoxidation of 1-octene. Vanadium pentoxide also has higher activity in this process.

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Abstract

Mesoporous titanium-containing silicas with different Titania contents were investigated. The structural parameters of the materials were characterized by low-temperature adsorption/desorption of nitrogen and X-ray diffraction analysis. The thermodesorption of water using the quasi-isothermal thermogravimetry as well as the differential scanning calorimetry were used to characterize thermal and surface properties of these materials. The adsorbed water layers and the concentration of weakly and strongly bound water as well as the surface free energy on the adsorbent/water interfaces were calculated. It was stated that the increase of Titania content causes a gradual decrease of specific surface area and formation of biporous structure inside the tested materials. The water thermodesorption from the surface proceeds in two or three stages, which is connected mainly with pore distribution and TiO2 content. One can observe the increase of the total surface free energy (ΔG Σ) with the increasing TiO2 content, but the largest ΔG Σ value at the adsorbent/strongly bound water interface is exhibited by the adsorbent of intermediate content (30%) of TiO2. Freezing temperature of water contained in the pores of the studied materials is connected largely with their porous structure. Due to the well developed porous structure, the water freezing process is a multi-stage one.

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Journal of Thermal Analysis and Calorimetry
Authors: Yu. Trach, V. Sydorchuk, O. Makota, S. Khalameida, R. Leboda, J. Skubiszewska-Zięba, and V. Zazhigalov

Abstract

Deposited catalysts composition H3PMo12O40/SiO2 and Ag/H3PMo12O40/SiO2 have been synthesized on the basis of fumed silica, including milling technique. Physical–chemical characteristics of prepared catalysts have been studied by means of XRD, DTA-TG, FTIR, UV–Vis spectroscopy, and adsorption of nitrogen. Catalysts possess meso- or meso-macroporous structure and contain deposited Keggin heteropolycompounds. Deposition of heteropolycompounds on support with high specific surface area results in increase of selectivity to epoxide in epoxidation reactions. The use of milling during catalyst synthesis leads to further growth of selectivity of epoxides formation.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Yanishpolskii, A. Pavlenko, V. Tertykh, V. Il'in, R. Leboda, and J. Skubiszewska-Zieba

Abstract  

Mesoporous titanium-containing silicas with TiO2 contents from 1 up to 70 mol% were prepared. The obtained samples have been characterized by the powder X-ray diffraction data, the diffuse reflectance infrared Fourier transform method, and nitrogen adsorption at 77 K. Specific surface area, total pore volume, distribution pore volume on pore sizes were determined from nitrogen adsorption isotherm for synthesized titanosilicas.

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Abstract  

Thermal analysis was used to study thermal behavior of the sulfonated ion exchange resin Duolite C20 in the hydrogen, sodium and calcium forms. The aim of this paper was to prepare spherical carbon adsorbents. SEM and AFM microscopic methods have been applied to describe their surface characteristics. It was stated that structural parameters of prepared active carbons depend on the kind of cation present in the resin. The use of calcium form of Duolite C20 as the initial polymer precursor allowed to obtain the active carbon with better yield and better developed pore structure compared with other forms of this ion exchanger.

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Abstract  

Physicochemical processes during thermal treatment of vanadium and phosphorus oxides mixture (1) as well as with diammonium hydrophosphate (2) in the closed system (autoclave) have been studied. In the first case, at 300 °C, the defective structure γ-VOPO4 is formed and in the second case, there was established possibility of synthesis of vanadyl hydrophosphate—the precursor of vanadyl pyrophosphate (the catalyst of n-butane oxidation to maleic anhydride). At the same time, various phases of mixed ammonium and vanadium phosphates were obtained at lower and higher temperatures.

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Journal of Thermal Analysis and Calorimetry
Authors: N. Ivashchenko, V. Tertykh, V. Yanishpolskii, J. Skubiszewska-Zięba, R. Leboda, and S. Khainakov

Abstract

A promising approach to control palladium nanoparticle sizes by application of silane modified silicas was suggested. The combination of reductive properties of silicon hydride groups and hydrophobic properties of alkylsilyl groups which act as agglomeration limiters for metal nanoparticles gives an opportunity to synthesize uniformly distributed particles with a specified size. Silicas modified with triethoxysilane (TES) and diisopropylchlorosilane (DIPCS), as well as, the combination of hexamethyldisilazane (HMDS) and triethoxysilane were applied for formation of such bifunctional matrices. Properties of the silane-modified silica samples and changes occurred during the formation of palladium nanoparticles were studied by IR spectroscopy. Thermal stability of surface chemical compounds was investigated by thermogravimetric analysis (TGA); low-temperature nitrogen adsorption was used to study structural properties of the applied materials. With the use of transmission electron microscopy (TEM) the dependence of palladium nanoparticle size on the nature of support surface layer was found.

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