Accurate determination of anomalous scattering factor near Fe<i>K</i>absorption edge

Okube, Maki; Sasaki, Satoshi

doi:10.1088/1742-6596/425/20/202002

Cited by 1 publication

(1 citation statement)

References 11 publications

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“…A priori knowledge from independent spectroscopic measurements indicates that the average Fe K-edge energy of a deactivated FCC particle lies for more than 95% of the present iron impurities within ±2 eV of the selected resonant measurement energy, 7123 eV. Thus, a subtraction of spatially registered off- and on-resonance tomograms, considering differences in scattering factor, provides a quantitative iron distribution tomogram at a spatial resolution of the acquired electron density tomogram, here 39 nm as determined by Fourier shell correlation, with an inherent uncertainty in iron concentration of ∼3%; see Figures S1–S3 and Supporting Methods for further information . The achieved resolution is suitable to probe around 85% of the occluded meso- and macropores when compared to mercury intrusion porosimetry (MIP) determined pore size/pore volume distribution, Figure S4 …”

Section: Resultsmentioning

confidence: 99%

Resonant Ptychographic Tomography Facilitates Three-Dimensional Quantitative Colocalization of Catalyst Components and Chemical Elements

et al. 2018

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The ability to localize selected chemical elements within individual components of functional matter is of great value to our understanding of material behavior. By means of resonant ptychographic X-ray computed tomography, we here provide such colocalization information with nanoscopic spatial resolution. Spatially correlated quantitative tomograms of electron density and iron concentration allowed the localization of native and feedstock-introduced iron impurities within the primary components of a prominent heterogeneous catalyst. Examinations found no direct evidence in favor of the currently suggested impurity-driven deactivation mechanisms of fluid catalytic cracking catalysts. The majority of iron impurities, present in the form of nanosized magnetite particulates, are found embedded in the outermost layer of an otherwise iron-poor, particle isolating amorphous silica–alumina envelope. Observations query both deactivation driven by impurity pore clogging and iron-impurity induced melting of catalyst components. The presented approach is general, extendable to secondary impurities or materials and spectroscopic ptychographic tomography. Future applications such as active-site localization and speciation in heterogeneous catalysis are envisioned.

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Section: Resultsmentioning

confidence: 99%