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

Abstract

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.

Nickel Poisoning of a Cracking Catalyst Unravelled by Single‐Particle X‐ray Fluorescence‐Diffraction‐Absorption Tomography

“…Moreover, this degraded surface region, is the one where in both samples Fe is accumulated, corroborating what has been previously demonstrated by Ihli et al. about Fe active role in pore clogging and ASA shell formation . Zeolite dealumination was studied by using again PCA and CA, this time by focusing on the zeolite [111] main reflection (Figure ): the ECAT1‐F1 particle, exposed to non‐hydrotreated feedstock and therefore rich in Ni, V and Fe, showed a shift in the 2 θ position of the [111] XRD peak compared to ECAT2, indicating a higher degree of dealumination.…”

Correlations between lignin content and structural robustness in plants revealed by X-ray ptychography

“…Combined with fast detection systems, this analysis will permit the three-dimensional imaging of larger specimens, reaching close to nanometric resolution and reducing the total data acquisition time. Finally, the tremendous potential of spectro-ptychography 51,52 (the combination of imaging with spectroscopic capabilities) will allow studies of nanoparticle biodistribution and the elucidation of nanoparticle biokinetics and bioactivity within intact tissues in plants and animals.…”

Hierarchical Structure of NiMo Hydrodesulfurization Catalysts Determined by Ptychographic X‐Ray Computed Tomography

“…While future investigations will expand on these observations examining among others the deactivation mechanism of industrially spent HDS catalysts, a more prominent effort is currently placed in the integration of X-ray spectroscopy, X-ray fluorescence and in situ capabilities within the framework of PXCT. [13] In consideration of next-generation synchrotron light sources, such integration will allow us on one hand to examine how differences in the carrier structure affect the distribution of the active phase and promoter in the catalyst. On the other, we can then also probe the chemical state and composition of the catalytically active phase during the reaction.…”

“…In this study, we introduce ptychographic X-ray computed nanotomography (PXCT) [9] to characterize the structural make-up of industrial-like HDS catalysts. PXCT is a nanotomography technique that provides quantitative tomograms of electron density when acquired away from sample-relevant X-ray absorption edges.…”