Xanes, Exafs and Reaction Studies of Some Well-Dispersed Ferric Oxide Catalysts

Ji, Wenliang; Kuo, Yu‐Ting; Shen, Shuling; Li, S.; Wang, H.

doi:10.1016/s0167-2991(08)64225-1

Cited by 6 publications

(2 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Understanding of a molecular species on the surface is particularly relevant to the description and design of working catalysts. Following the approach established by Knözinger and Zhao and as a result of the development of XAFS technique, more work concerning the cluster-derived species has been recently reported. − , Among them, the support surface itself, which favors or disfavors some specific structures, was emphasized in our work. − ,, From this paper, we will extend the approach to the supported iron oxide catalysts.…”

Section: Introductionmentioning

confidence: 93%

Surface Coordinate Geometry of Iron Catalysts: Distinctive Behaviors of Fe/Al₂O₃ in CO Hydrogenation

et al. 1996

View full text Add to dashboard Cite

Two well-defined iron catalysts, Fe(II)/Al2O3 (4.5 wt %) and Fe2O3/Al2O3 (1.5 wt %), have been studied using Fe K-edge X-ray absorption fine structure (XAFS). The total coordination number of the nearest oxygen neighbors is found to be 4.9 for the former and 5.7 for the latter, but the average Fe−O bond length remains the same, 1.98 Å. The nearest iron neighbors at 2.95−2.97 Å are observed for both the catalysts, but for the Fe2O3/Al2O3, further two iron neighbors at 3.42 and 3.86 Å are also present. The fact that the shell radius of 3.42 Å is times longer than that of the first nearest irons is consistent with what is expected from the para- and the meta-positions surrounding the same oxygen on the γ-Al2O3 (111) plane but is at variance with the estimation made for the (110) plane. Two geometrical models proposed for the catalysts stoichiometrically explain why the higher metal loading only leads to one type of the iron neighbors but the lower metal loading unexpectedly leads to three types of iron neighbors.

show abstract

Section: Introductionmentioning

confidence: 93%

Surface Coordinate Geometry of Iron Catalysts: Distinctive Behaviors of Fe/Al₂O₃ in CO Hydrogenation

et al. 1996

View full text Add to dashboard Cite

show abstract

“…The shapes of our XANES spectra including pre-edge and post-edge features, the edge positions, and shapes are in close resemblance to Fe 2 O 3 /ZrO 2 systems reported previously. 32,37,38 For example, in the study of Yamamato et al, 38 an increase in the intensity of the pre-edge peak was also attributed to distortions around the local structure of Fe (due to the formation of a solid solution between zirconia and iron oxide). Similarly, Li et al 32 and Ji et al 38 also observed two distinct peaks at 1.6 and 3 Å in the Fourier transformed EXAFS spectra of Fe 2 O 3 /ZrO 2 .…”

mentioning

confidence: 99%

ZrO₂-Supported Fe₂O₃ for Chemical-Looping-Based Hydrogen Production: Effect of pH on Its Structure and Performance As Probed by X-ray Absorption Spectroscopy and Electrical Conductivity Measurements

et al. 2016

View full text Add to dashboard Cite

Chemical looping is a promising process to produce high purity H 2 while simultaneously capturing CO 2 . The key requirement for this process is the availability of oxygen carriers that possess a high cyclic redox stability, resistance to carbon deposition, and thermal sintering. In this study, ZrO 2 -supported Fe 2 O 3based oxygen carriers were developed using a coprecipitation technique. We assess in detail the influence of the key synthesis parameter, i.e., the pH value at which the precipitation was performed, on the morphological properties, chemical composition, local structure, and cyclic redox stability. The performance of the new oxygen carriers was compared to unsupported Fe 2 O 3 and Al 2 O 3 -supported Fe 2 O 3 . A higher degree of disorder in the local structure of oxygen carriers precipitated at low pH values was confirmed by X-ray absorption spectroscopy (XAS) measurements. Electrical conductivity measurements showed that supporting Fe 2 O 3 on ZrO 2 lowered significantly the activation energy for charge transport when compared to pure Fe 2 O 3 . In line with this observation, ZrO 2supported oxygen carriers displayed a very high and stable H 2 yield over 15 redox cycles when precipitation was performed at pH > 5.

show abstract

Surface coordinate geometry of iron catalysts: hydrogenation of CO2 over Fe/ZrO2 prepared by a novel method

et al. 1995

View full text Add to dashboard Cite

Xanes, Exafs and Reaction Studies of Some Well-Dispersed Ferric Oxide Catalysts

Cited by 6 publications

References 2 publications

Surface Coordinate Geometry of Iron Catalysts: Distinctive Behaviors of Fe/Al₂O₃ in CO Hydrogenation

Surface Coordinate Geometry of Iron Catalysts: Distinctive Behaviors of Fe/Al₂O₃ in CO Hydrogenation

ZrO₂-Supported Fe₂O₃ for Chemical-Looping-Based Hydrogen Production: Effect of pH on Its Structure and Performance As Probed by X-ray Absorption Spectroscopy and Electrical Conductivity Measurements

Surface coordinate geometry of iron catalysts: hydrogenation of CO2 over Fe/ZrO2 prepared by a novel method

Contact Info

Product

Resources

About

Xanes, Exafs and Reaction Studies of Some Well-Dispersed Ferric Oxide Catalysts

Cited by 6 publications

References 2 publications

Surface Coordinate Geometry of Iron Catalysts: Distinctive Behaviors of Fe/Al2O3 in CO Hydrogenation

Surface Coordinate Geometry of Iron Catalysts: Distinctive Behaviors of Fe/Al2O3 in CO Hydrogenation

ZrO2-Supported Fe2O3 for Chemical-Looping-Based Hydrogen Production: Effect of pH on Its Structure and Performance As Probed by X-ray Absorption Spectroscopy and Electrical Conductivity Measurements

Surface coordinate geometry of iron catalysts: hydrogenation of CO2 over Fe/ZrO2 prepared by a novel method

Contact Info

Product

Resources

About

Surface Coordinate Geometry of Iron Catalysts: Distinctive Behaviors of Fe/Al₂O₃ in CO Hydrogenation

Surface Coordinate Geometry of Iron Catalysts: Distinctive Behaviors of Fe/Al₂O₃ in CO Hydrogenation

ZrO₂-Supported Fe₂O₃ for Chemical-Looping-Based Hydrogen Production: Effect of pH on Its Structure and Performance As Probed by X-ray Absorption Spectroscopy and Electrical Conductivity Measurements