Time-resolved in situ XANES study of the redox properties of Ce0.9Zr0.1O2 mixed oxides

Zimicz, Maria Genoveva; Larrondo, Susana Adelina; Prado, Rogério Junqueira; Lamas, Diego G.

doi:10.1016/j.ijhydene.2012.01.162

Cited by 26 publications

(29 citation statements)

References 19 publications

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“…Appropriate textural properties were obtained, specially higher specific surface area and pore volume compared to sol-gel ZDC samples [39]. And finally, in situ XANES results revealed a high reduction rate of Ce 3+ to Ce 4+ at 500 • C under TPR, which is directly correlated to higher catalytical activity.…”

Section: Discussionmentioning

confidence: 84%

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Structural studies of mesoporous ZrO2-CeO2 and ZrO2-CeO2/SiO2 mixed oxides for catalytical applications

Bacani

Martins

Fantini

et al. 2016

Journal of Alloys and Compounds

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In this work the synthesis of ZrO 2 -CeO 2 and ZrO 2 -CeO 2 /SiO 2 were developed, based on the process to form ordered mesoporous materials such as SBA-15 silica. The triblock copolymer Pluronic P-123 was used as template, aiming to obtain crystalline single phase walls and larger specific surface area, for future applications in catalysis. Small angle X-ray scattering and X-ray diffraction results showed a relationship between ordered pores and the material crystallization. 90% of CeO 2 leaded to single phase homogeneous ceria-zirconia solid solution of cubic fluorite structure (Fm3m). The SiO 2 addition improved structural and textural properties as well as the reduction behaviour at lower temperatures, investigated by X-ray Absorption near edge spectroscopy measurements under H 2 atmosphere.

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Section: Discussionmentioning

confidence: 84%

“…promoted a higher reduction of Ce 4+ under lower temperatures compared to materials synthesized via gel-combustion routes [38,39].…”

Section: Zro 2 -Ceo 2 /Siomentioning

confidence: 94%

Structural studies of mesoporous ZrO2-CeO2 and ZrO2-CeO2/SiO2 mixed oxides for catalytical applications

Bacani

Martins

Fantini

et al. 2016

Journal of Alloys and Compounds

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“…These tests were carried out in the D06A-DXAS beamline of the Brazilian Synchrotron Light Laboratory. Sample preparation and method of analysis of XANES spectra were previously reported 13 . From the fitting of the absorption profile, the evolution of the degree of reduction "α" of Ce 4+ cations when the samples were subjected to different atmospheres was obtained.…”

Section: Characterizationmentioning

confidence: 99%

“…XANES spectra were fitted as a linear combination of standard spectra, as it was previously reported 13,18 . XANES experiments in methane oxidation conditions were conducted only for sample GS, due to the poor catalytic activity of sample LS previously observed in conventional catalytic tests 14 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 The only carbonated product detected in the effluent gas was carbon dioxide (CO 2 ).…”

Section: In Situ Xanes Experimentsmentioning

confidence: 99%

XPD and XANES Studies of Ce_0.9Zr_0.1O₂ Nanocatalysts under Redox and Catalytic CH₄ Oxidation Conditions

et al. 2015

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The aim of this work is to take further insight into the structural stability of ceriumzirconium catalysts under reducing, oxidizing and reaction conditions. In situ synchrotron based techniques (XANES and XPD) were used in order to determine the stability of crystal structure and the oxidation state of cerium cations in the reaction conditions prevailing in the catalytic studies. In situ XPD studies in 5 mol% H 2 atmosphere revealed that no structural changes occur until 870°C. At this temperature, the sample synthesized with glycine, which presents lower crystallite agglomeration, segregated a small quantity of a reduced phase. On the contrary, the solid synthesized with lysine, with more agglomerated crystallites, does not show structural changes in all the temperature range.Reoxidation treatments in 5 mol % O 2 revealed that at 750°C the segregated phase disappears and the original cubic structure is restored.In situ XANES studies in the Ce L III absorption edge indicate that under catalytic reaction conditions, the degree of reduction of Ce 4+ is low, allowing the occurrence of methane oxidation. The solid is capable to deliver the oxygen of its structure when no oxygen is fed into the reactor until the 50 % of cerium cations become reduced, triggering the deactivation process. Therefore, it is clear for these studies that the Ce 4+ to Ce 3+ ratio in the lattice is governing the catalytic behaviour of the solid. The catalytic results collected during in situ XANES experiments are in excellent agreement with our previous catalytic studies performed with a laboratory fixed bed reactor.

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“…Although the benefit of the use of nanostructured materials has already been pointed out by several authors, the studies of this type of materials from the basic point of view to understand the mechanisms underlying the different processes of catalysis are scarce. In recent years, our research groups have investigated CeO2-based and NiO/CeO2-based catalysts by dispersive X-ray absorption spectroscopy (DXAS) under different atmospheres and reaction conditions [15,16,17,18]. Samples with different morphologies were analyzed, finding that CeO2-based materials with small average crystallite size and high specific surface area exhibit the best properties, reaching high reducibility and excellent methane conversion for intermediate temperatures [19].…”

Section: Introductionmentioning

confidence: 99%

Temperature-Programmed Reduction and Dispersive X-Ray Absorption Spectroscopy Studies of CeO<sub>2</sub>-Based Nanopowders for Intermediate-Temperature Solid-Oxide Fuel Cell Anodes

Bellora¹,

Sacanell²,

Huck‐Iriart³

et al. 2019

MSA

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In this work, we study the influence of the average crystallite size and dopant oxide on the reducibility of CeO2-based nanomaterials. Samples were prepared from commercial Gd2O3-, Sm2O3-and Y2O3-doped CeO2 powders by calcination at different temperatures ranging between 400 and 900ºC and characterized by X-ray powder diffraction, transmission electron microscopy and BET specific surface area. The reducibility of the samples was analyzed by temperatureprogrammed reduction and in situ dispersive X-ray absorption spectroscopy techniques. Our results clearly demonstrate that samples treated at lower temperatures, of smallest average crystallite size and highest specific surface areas, exhibit the best performance, while Gd2O3doped ceria materials display higher reducibility than Sm2O3-and Y2O3-doped CeO2.

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Time-resolved in situ XANES study of the redox properties of Ce0.9Zr0.1O2 mixed oxides

Cited by 26 publications

References 19 publications

Structural studies of mesoporous ZrO2-CeO2 and ZrO2-CeO2/SiO2 mixed oxides for catalytical applications

Structural studies of mesoporous ZrO2-CeO2 and ZrO2-CeO2/SiO2 mixed oxides for catalytical applications

XPD and XANES Studies of Ce_0.9Zr_0.1O₂ Nanocatalysts under Redox and Catalytic CH₄ Oxidation Conditions

Temperature-Programmed Reduction and Dispersive X-Ray Absorption Spectroscopy Studies of CeO<sub>2</sub>-Based Nanopowders for Intermediate-Temperature Solid-Oxide Fuel Cell Anodes

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Time-resolved in situ XANES study of the redox properties of Ce0.9Zr0.1O2 mixed oxides

Cited by 26 publications

References 19 publications

Structural studies of mesoporous ZrO2-CeO2 and ZrO2-CeO2/SiO2 mixed oxides for catalytical applications

Structural studies of mesoporous ZrO2-CeO2 and ZrO2-CeO2/SiO2 mixed oxides for catalytical applications

XPD and XANES Studies of Ce0.9Zr0.1O2 Nanocatalysts under Redox and Catalytic CH4 Oxidation Conditions

Temperature-Programmed Reduction and Dispersive X-Ray Absorption Spectroscopy Studies of CeO&lt;sub&gt;2&lt;/sub&gt;-Based Nanopowders for Intermediate-Temperature Solid-Oxide Fuel Cell Anodes

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Product

Resources

About

XPD and XANES Studies of Ce_0.9Zr_0.1O₂ Nanocatalysts under Redox and Catalytic CH₄ Oxidation Conditions

Temperature-Programmed Reduction and Dispersive X-Ray Absorption Spectroscopy Studies of CeO<sub>2</sub>-Based Nanopowders for Intermediate-Temperature Solid-Oxide Fuel Cell Anodes