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In-situ XAS study of catalytic N[sub]2O decomposition over CuO/CeO[sub]2 catalysts
Elena Tchernychova, Petar Djinović, Iztok Arčon, Maxim Zabilsky, Albin Pintar, 2021, original scientific article

Abstract: We performed in‐situ XAS study of N 2 O decomposition over CuO/CeO 2 catalysts. The Cu K‐edge and Ce L 3 ‐edge XANES and EXAFS analyses revealed the dynamic and crucial role of Cu 2+ /Cu + and Ce 4+ /Ce 3+ ionic pairs during the catalytic reaction. We observed the initial formation of reduced Cu + and Ce 3+ species during activation in helium atmosphere at 400 °C, while concentration of these species decreased significantly during steady‐state nitrous oxide degradation reaction (2500 ppm N 2 O in He at 400 °C). In‐situ EXAFS analysis further revealed a crucial role of copper‐ceria interface in this catalytic reaction. We observed dynamic changes in average number of Cu‐Ce scatters under reaction conditions, indicating an enlarging the interface between both copper and ceria phases, where electron and oxygen transfer occurs.
Found in: ključnih besedah
Keywords: in-situ XAS, Cu EXAFS, CuO/CeO2 nanorod catalys, N2O decomposition
Published: 29.01.2021; Views: 1046; Downloads: 0
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Structure and population of complex ionic species in FeCl[sub]2 aqueous solution by X-ray absorption spectroscopy
Matjaž Valant, Iztok Arčon, Uroš Luin, 2022, original scientific article

Abstract: Technologies for mass production require cheap and abundant materials such as ferrous chloride (FeCl2). The literature survey shows the lack of experimental studies to validate theoretical conclusions related to the population of ionic Fe-species in the aqueous FeCl2 solution. Here, we present an in situ X-ray absorption study of the structure of the ionic species in the FeCl2 aqueous solution at different concentrations (1–4 molL−1) and temperatures (25–80 ◦C). We found that at low temperature and low FeCl2 concentration, the octahedral first coordination sphere around Fe is occupied by one Cl ion at a distance of 2.33 (±0.02) Å and five water molecules at a distance of 2.095 (±0.005) Å. The structure of the ionic complex gradually changes with an increase in temperature and/or concentration. The apical water molecule is substituted by a chlorine ion to yield a neutral Fe[Cl2(H2O)4]0. The observed substitutional mechanism is facilitated by the presence of the intramolecular hydrogen bonds as well as entropic reasons. The transition from the single charged Fe[Cl(H2O)5]+ to the neutral Fe[Cl2(H2O)4]0 causes a significant drop in the solution conductivity, which well correlates with the existing conductivity models.
Found in: ključnih besedah
Summary of found: ...FeCl2 solution. Here, we present an in situ X-ray absorption study of the structure of...
Keywords: structure, population, ionic species, aqueous ferrous chloride, in situ X-ray absorption spectroscopy
Published: 24.01.2022; Views: 400; Downloads: 8
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