Search Results

You are looking at 1 - 8 of 8 items for :

  • Author or Editor: V. Sydorchuk x
  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All Modify Search

Preparation of microspherical granules from aerosilogels

The way of spray drying in overheated water steam

Journal of Thermal Analysis and Calorimetry
Authors: Jadwiga Skubiszewska-Zięba and V. Sydorchuk

Abstract  

The influence of the conditions of aerosil dispersion spray drying process in the medium of overheated water steam on the formation of microspheric granules and their porous structure was studied. Water and ammonium solutions as aerosil particles dispersing agents and water steam and air as heat carriers were used. It was stated that the effects of spray drying depend on the kind of dispersing medium and on the conditions of atmosphere and temperature at which drying and forming of aerosilogel granules takes place.

Restricted access
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.

Restricted access

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).

Restricted access
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.

Restricted access
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.

Restricted access

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.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: V. Sydorchuk, W. Janusz, S. Khalameida, E. Skwarek, J. Skubiszewska-Zięba, R. Leboda, and V. Zazhigalov

Abstract

Deposited zirconium phosphate samples on the base of silica and titania have been prepared using the sol–gel and mechanochemical methods. Porous structure, phase composition, and electrokinetic parameters have been studied by means of nitrogen adsorption–desorption, XRD, DTA-TG, FTIR, electrophoresis, and potentiometric titration. The compositions possess varied parameters of porous structure, structure of deposited phase, and electrokinetic properties depending on support nature and synthesis conditions.

Open access
Journal of Thermal Analysis and Calorimetry
Authors: E. Skwarek, S. Khalameida, W. Janusz, V. Sydorchuk, N. Konovalova, V. Zazhigalov, J. Skubiszewska-Zięba, and R. Leboda

Abstract

Mechanochemical activation of individual V2O5, MoO3 and mixed vanadium-molybdenum oxide system in various media (air, water, and ethanol) has been studied. Powder X-ray diffraction, nitrogen adsorption–desorption, thermogravimetric and chemical analysis, FTIR and Raman spectroscopy, and scanning electron microscopy have been used for research of prepared milled samples. The electrokinetic properties (dependence zeta potential—pH, position of isoelectric point) of individual V2O5, MoO3 and mixed vanadium–molybdenum oxide system, synthesized via mechanochemical treatment in various medium, in aqueous solutions of electrolytes also have been determined. Initial, milled, and spent samples are characterized with the help of XRD, FTIR and Raman spectroscopy, and SEM and adsorption of nitrogen. The catalytic properties of vanadium–molybdenum oxide composition activated in different media have been investigated in reaction of oxidation dehydrogenation of propane.

Restricted access