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A series of Nb-doped (0–23 wt%) cryptomelane catalyst (Nb-K-OMS-2) was synthesized and thoroughly characterized by XRD, TEM/EDX, XRF, XPS, XAS, UV-Vis, and Raman techniques corroborated by the work function measurements. The obtained... more
A series of Nb-doped (0–23 wt%) cryptomelane catalyst (Nb-K-OMS-2) was synthesized and thoroughly characterized by XRD, TEM/EDX, XRF, XPS, XAS, UV-Vis, and Raman techniques corroborated by the work function measurements. The obtained catalysts were tested for soot oxidation (Printex U) in model tight and loose contact modes. It was shown that the catalytic properties of the Nb-K-OMS-2 are controlled by the amount of Nb dopant in a strongly non-monotonous way. The introduction of niobium gives rise to the strain in the cryptomelane lattice, accompanied by significant Mn+3/Mn+4 ratio variations and concomitant work function changes. The isotopic exchange experiments revealed that the catalytic activity of the Nb-OMS-2 catalysts in soot combustion proceeds via the pathways, where both the activated suprafacial 18O and the surface 16O2− species participate together in the reaction. The niobium doping level controls the non-monotonous changes of the catalyst work function and the lattice...
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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... more
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 CH
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Structural (XRD) and spectroscopic (EPR, IR and Raman) investigations were performed to elucidate the influence of CeO2 content on the phase composition and surface chemistry of CexZr1−xO2 solid solutions (x=0.10–0.85), interacting with... more
Structural (XRD) and spectroscopic (EPR, IR and Raman) investigations were performed to elucidate the influence of CeO2 content on the phase composition and surface chemistry of CexZr1−xO2 solid solutions (x=0.10–0.85), interacting with NO and NO2 in the absence and presence of oxygen. Strong influence of ceria loading on the adsorption modes of both nitrogen oxides and the nature of the
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Research Interests: Scanning Electron Microscopy, Morphology, Phase Transitions, Differential scanning calorimetry, Nucleation, and 15 moreDSC, Phase transition, XRD, Texture, Thermogravimetry, Thermal Analysis, Surface Structure, Chemical Precipitation, X ray diffraction, Differential Thermal Analysis, Surface Properties, Aqueous Solution, Coalescence, Thermal Effects, and Porosimetry
The interaction of nitric oxide with Ce0. 75Zr0. 25O2 solid solution were investigated by means of EPR and IR spectroscopies. The influence of adsorption parameters such as adsorption temperature and pressure, presence of the O2... more
The interaction of nitric oxide with Ce0. 75Zr0. 25O2 solid solution were investigated by means of EPR and IR spectroscopies. The influence of adsorption parameters such as adsorption temperature and pressure, presence of the O2 co-reactant on the nature and ...
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Nanocrystalline tetragonal zirconia was obtained from ZrOCl2 via the modified forced hydrolysis method combined with aging of the hydrous amorphous precipitate in the mother liquor at 100 °C for 48 h (pH = 9.3). The role of the... more
Nanocrystalline tetragonal zirconia was obtained from ZrOCl2 via the modified forced hydrolysis method combined with aging of the hydrous amorphous precipitate in the mother liquor at 100 °C for 48 h (pH = 9.3). The role of the precipitation and aging temperatures in the metastabilization of the tetragonal ZrO2 polymorph is discussed in terms of the structural and textural data of the resultant oxide. The influence of low concentrations of silica (0.01 – 0.35 wt. % Si), spontaneously leached from the glass vessel or intentionally introduced to the parent solution, was shown to be a vital factor, controlling the phase composition of the final prepared zirconia. Using the concepts of zirconium aquatic chemistry, this effect was explained by incorporation of silicates into hydrous zirconia protostructures.
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Abstract. Hydrous zirconia was prepared by hydrolysis of ZrOCb. The influence of precipitation temperature, aging and addition of small amounts of Si on crystallization, phase composition and phase transformations was investigated. Aging... more
Abstract. Hydrous zirconia was prepared by hydrolysis of ZrOCb. The influence of precipitation temperature, aging and addition of small amounts of Si on crystallization, phase composition and phase transformations was investigated. Aging at 373 К and pH~ 9 in ...
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The structure and surface properties of ZrO2 strongly depend on its preparation. In the present work the impact of prolonged aging at basic conditions (pH = 9, T = 100°C, t = 48 h), on the phase composition and textural properties,... more
The structure and surface properties of ZrO2 strongly depend on its preparation. In the present work the impact of prolonged aging at basic conditions (pH = 9, T = 100°C, t = 48 h), on the phase composition and textural properties, obtained by calcination of the precipitate, was investigated using several techniques conjointly (DTA/TG, DSC, XRD, porosimetry). The thermal effects
Research Interests: Scanning Electron Microscopy, Morphology, Phase Transitions, Differential scanning calorimetry, Nucleation, and 15 moreDSC, Phase transition, XRD, Texture, Thermogravimetry, Thermal Analysis, Surface Structure, Chemical Precipitation, X ray diffraction, Differential Thermal Analysis, Surface Properties, Aqueous Solution, Coalescence, Thermal Effects, and Porosimetry
... Molybdena Obtained by Slurry Deposition Andrzej Adamski Æ Piotr Zapała Æ Paweł Jakubus Æ Zbigniew Sojka Published online: 17 April 2009 Ó Springer Science+Business Media, LLC 2009 ... Bielanski A (1987) Fundamental inorganic... more
... Molybdena Obtained by Slurry Deposition Andrzej Adamski Æ Piotr Zapała Æ Paweł Jakubus Æ Zbigniew Sojka Published online: 17 April 2009 Ó Springer Science+Business Media, LLC 2009 ... Bielanski A (1987) Fundamental inorganic chemistry. PWN, Warsaw 17. ...
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A comprehensive periodic DFT/PW91 study of water sorption (0.25< θ< 1) on monoclinic ZrO 2 (P2 1/c) nanocrystals was performed by means of the plane wave periodic DFT calculations joint with statistical thermodynamics. All... more
A comprehensive periodic DFT/PW91 study of water sorption (0.25< θ< 1) on monoclinic ZrO 2 (P2 1/c) nanocrystals was performed by means of the plane wave periodic DFT calculations joint with statistical thermodynamics. All planes,(001),(110),(011),(-101),(111) ...
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Hydrogen production by photocatalytic reforming of aqueous solutions of ethanol and glycerol was studied with the use of impregnated and embedded CuO(x)/TiO(2) photocatalysts. Embedded CuO(x)@TiO(2) was prepared by a water-in-oil... more
Hydrogen production by photocatalytic reforming of aqueous solutions of ethanol and glycerol was studied with the use of impregnated and embedded CuO(x)/TiO(2) photocatalysts. Embedded CuO(x)@TiO(2) was prepared by a water-in-oil microemulsion method, which consists in the formation of Cu nanoparticles in the microemulsion followed by controlled hydrolysis and condensation of tetraisopropyl orthotitanate with the aim of covering the protected metal particles with a surrounding layer of porous titanium oxyhydroxide. Mild calcination leads to the complete removal of the organic residues, the crystallization of TiO(2), and an unavoidable oxidation of copper. Two reference samples were prepared by classical wet impregnation of preformed TiO(2) with different ratios of anatase, rutile, and brookite polymorphs. The two supports were prepared by sol-gel (TiO(2)-SG) and microemulsion (TiO(2)-ME) methods. Superior performances have been observed for the embedded system, which shows higher hydrogen production rates with respect to the impregnated systems using either ethanol or glycerol as sacrificial molecules. Deep structural characterization of the materials has been performed by coupling high resolution transmission electron microscopy (HRTEM), high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), X-ray absorption fine structure (XAFS), and electron paramagnetic resonance (EPR) techniques. Correlation between copper oxidation state and its dispersion and reactivity has been attempted. Finally, the stability of the CuO(x)/TiO(2) catalysts was also studied with respect to carbonaceous deposits and copper leaching.
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ABSTRACT The temperature dependence of EPR spectra provides information on the mobility of paramagnetic species at the gas (liquid)/solid interface and in the bulk of solids. Changes in the environment of molecules on solid surfaces... more
ABSTRACT The temperature dependence of EPR spectra provides information on the mobility of paramagnetic species at the gas (liquid)/solid interface and in the bulk of solids. Changes in the environment of molecules on solid surfaces caused by their motion occurring upon thermal treatment at various temperatures are observed. Superoxide radical can migrate from Co(III) to Mg(II) surface sites of the CoO–MgO solid solutions. In aqueous solutions transition metal ions coordinate water molecules, forming aquacomplexes which are usually free to tumble within the liquid medium. Their mobility is, however, strongly modified in the vicinity of the solid surface or inside the narrow pores. In solids the migration of paramagnetic species from the surface into the bulk is controlled by the temperature of thermal treatment. In the case of V2O5–ZrO2 catalyst this process is strongly influenced by the phase transitions occurring in the solid matrix and by the presence of alkali metals.
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ABSTRACT A series of undoped and potassium-doped catalysts for the oxidative dehydrogenation of propane, based on zirconia-supported V2O5 was investigated by XRD and ESR techniques. The chemical state of the surface and bulk vanadium... more
ABSTRACT A series of undoped and potassium-doped catalysts for the oxidative dehydrogenation of propane, based on zirconia-supported V2O5 was investigated by XRD and ESR techniques. The chemical state of the surface and bulk vanadium species and of the ZrO2 matrix was investigated as a function of the calcination temperature and the presence of dopants. It was found that potassium improves the dispersion of surface vanadium species and affects the temperature of the phase transitions of zirconia. These two effects facilitate the incorporation of vanadium (IV) into the ZrO2 matrix. The formation of substitutional solid solution was revealed by Rietveld analysis.
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FTIR study of iron and aluminium forms of zeolite MCM-58 showed that location of heteroatoms in this IFR structure depends on the type of heteroatom. The combination of the pyridine and CO adsorption allowed determination of the... more
FTIR study of iron and aluminium forms of zeolite MCM-58 showed that location of heteroatoms in this IFR structure depends on the type of heteroatom. The combination of the pyridine and CO adsorption allowed determination of the concentration of hydroxyls in the ...
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Undoped and alkali-doped zirconia-supported vanadia catalysts for the oxidative dehydrogenation of propane were prepared by impregnation and characterized by various techniques. The chemical state of surface and bulk vanadium was... more
Undoped and alkali-doped zirconia-supported vanadia catalysts for the oxidative dehydrogenation of propane were prepared by impregnation and characterized by various techniques. The chemical state of surface and bulk vanadium was investigated as a function of the calcination temperature, VâOâ loading, and the nature and content of alkali-metal additives. It is found that on the surface vanadium is present in the
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Adsorption of trimethyl-, triethyl- and tri(t-butyl)phosphine which have differing Tolman angles was used for the EPR characterization of the coordination sphere and spatial accessibility of Mo5+ ions present on the surface of reduced... more
Adsorption of trimethyl-, triethyl- and tri(t-butyl)phosphine which have differing Tolman angles was used for the EPR characterization of the coordination sphere and spatial accessibility of Mo5+ ions present on the surface of reduced supported MoSiO2 catalysts. Due to the presence of 31P nuclei a well resolved 1:2:1 ligand superhyperfine structure (ca. 3 mT) was observed even in the first derivative
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Structural differences in zirconia-supported vanadia, containing 3mol% V2O5, obtained by slurry deposition and wet impregnation were elucidated using Raman, EPR and XRD methods, supported by Rietveld refinement. The preparation method... more
Structural differences in zirconia-supported vanadia, containing 3mol% V2O5, obtained by slurry deposition and wet impregnation were elucidated using Raman, EPR and XRD methods, supported by Rietveld refinement. The preparation method strongly determines both the heterogeneity of the surface VOx species and incorporation of the V4+ ions into the zirconia matrix. Slurry deposition favors the formation of isolated or two-dimensional oxovanadium
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Samples of the catalysts containing 0.5, 5.0 and 40mol.% of V2O5 supported on the ZrO2 and Nb2O5 oxides, prepared by wet impregnation, were characterized by XRD and EPR. Their catalytic activity was tested in methanol and acetone total... more
Samples of the catalysts containing 0.5, 5.0 and 40mol.% of V2O5 supported on the ZrO2 and Nb2O5 oxides, prepared by wet impregnation, were characterized by XRD and EPR. Their catalytic activity was tested in methanol and acetone total oxidation. Vanadium bronze samples were synthesized as a reference. Redox properties of surface oxovanadium entities were investigated by adsorption of NO probe
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Structural (XRD) and spectroscopic (EPR, IR and Raman) investigations were performed to elucidate the influence of CeO2 content on the phase composition and surface chemistry of CexZr1−xO2 solid solutions (x=0.10–0.85), interacting with... more
Structural (XRD) and spectroscopic (EPR, IR and Raman) investigations were performed to elucidate the influence of CeO2 content on the phase composition and surface chemistry of CexZr1−xO2 solid solutions (x=0.10–0.85), interacting with NO and NO2 in the absence and presence of oxygen. Strong influence of ceria loading on the adsorption modes of both nitrogen oxides and the nature of the
Research Interests:
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The interaction of nitric oxide with Ce0. 75Zr0. 25O2 solid solution were investigated by means of EPR and IR spectroscopies. The influence of adsorption parameters such as adsorption temperature and pressure, presence of the O2... more
The interaction of nitric oxide with Ce0. 75Zr0. 25O2 solid solution were investigated by means of EPR and IR spectroscopies. The influence of adsorption parameters such as adsorption temperature and pressure, presence of the O2 co-reactant on the nature and ...
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ABSTRACT Zeolitic materials with combined micro and mesoporous structure were synthesized using two different approaches. A first series of the samples was obtained by impregnation method. Suspension of Beta nanoparticles was impregnated... more
ABSTRACT Zeolitic materials with combined micro and mesoporous structure were synthesized using two different approaches. A first series of the samples was obtained by impregnation method. Suspension of Beta nanoparticles was impregnated on SBA-15 mesoporous silica. In the second synthesis route, called non-templating method, Beta nanoparticles were aggregated under specified conditions with the formation of micro-mesoporous material (without the use of the mesopore directing agent). Micropores were present in the zeolite nanoparticles, while mesopores were located in the interparticle space. The combined micro and mesoporous structure of the obtained materials, exhibiting the properties of Beta zeolite, was confirmed by nitrogen sorption measurements, XRD, TGA and DRIFT techniques. The hierarchical porous structure of the samples resulted in an improved accessibility of ion-exchange positions in comparison to conventional Beta zeolite and allowed the introduction of iron, nearly exclusively in the form of monomeric Fe3+ cations and oligomeric FexOy species. The iron modified micro-mesoporous samples as well as SBA-15 and Beta zeolite (as reference samples), were tested as catalysts of N2O decomposition. The most promising micro-mesoporous sample (Fe-Beta/meso) was tested as catalyst in the reactions of N2O decomposition and N2O reduction with CO at different composition of gas mixture (in the presence of O-2, H2O and NO). Catalytic activity of iron-exchanged, micro-mesoporous Beta and conventional Beta zeolites in the reaction of N2O conversion was very similar.