3D Nanoscale Chemical Imaging of the Distribution of Aluminum Coordination Environments in Zeolites with Soft X‐Ray Microscopy

Aramburo, Luis R.; Liu, Yijin; Tyliszczak, Tolek; Groot, Frank M. F. de; Andrews, Joy C.; Weckhuysen, Bert M.

doi:10.1002/cphc.201201015

Cited by 34 publications

(38 citation statements)

References 31 publications

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“…These differences have been observed before in similar fluorescence staining experiments of FCC particles, but the unique correlative approach presented here allows us now to unambiguously link reactivity to ultrastructure 5, 19. The differences seen in reactivity may be explained by differences in the distribution of Al coordination in the zeolite particles, which has been shown to vary within ZSM‐5 particles32 as well as in zeolite Y embedded in FCC catalysts 10. Furthermore, previous research has shown polarization dependence of the fluorescent products can also play a role in ZSM‐5 containing FCC particles, although this does not apply to reactivity differences within one zeolite domain 33.…”

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confidence: 71%

Integrated Transmission Electron and Single‐Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

et al. 2017

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Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single‐molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure–reactivity information was obtained for 100 nm thin, microtomed sections of a single FCC catalyst particle using this novel SMF‐TEM high‐resolution combination. High reactivity in a thiophene oligomerization probe reaction correlated well with TEM‐derived zeolite locations, while matrix components, such as clay and amorphous binder material, were found not to display activity. Differences in fluorescence intensity were also observed within and between distinct zeolite aggregate domains, indicating that not all zeolite domains are equally active.

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confidence: 71%

Integrated Transmission Electron and Single‐Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

et al. 2017

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“…Our group has recently been applying STXM in the field of zeolite chemistry and catalysis. [25][26][27]77 Using this experience it was possible to observe the crystallization of the extra-framework AlPO 4 phase of H-mordenite in space and time by application of an in situ nanoreactor. 28 X-ray tomography was used to create a 3-D nanoscale chemical reconstruction of the AlPO 4 phase in a single H-mordenite aggregate for the first time.…”

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confidence: 98%

Aluminum-Phosphate Binder Formation in Zeolites as Probed with X-ray Absorption Microscopy

et al. 2014

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In this work, three industrially relevant zeolites with framework topologies of MOR, FAU and FER have been explored on their ability to form an AlPO4 phase by reaction of a phosphate precursor with expelled framework aluminum. A detailed study was performed on zeolite H-mordenite, using in situ STXM and soft X-ray absorption tomography, complemented with (27)Al and (31)P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, XRD, FT-IR spectroscopy, and N2 physisorption. Extraframework aluminum was extracted from steam-dealuminated H-mordenite and shown to dominantly consist of amorphous AlO(OH). It was found that phosphoric acid readily reacts with the AlO(OH) phase in dealuminated H-mordenite and forms an extraframework amorphous AlPO4 phase. It was found that while AlPO4 crystallizes outside of the zeolitic channel system forming AlPO4 islands, AlPO4 that remains inside tends to stay more amorphous. In the case of ultrastable zeolite Y the FAU framework collapsed during phosphatation, due to extraction of framework aluminum from the lattice. However, using milder phosphatation conditions an extraframework AlPO4 α-cristobalite/tridymite phase could also be produced within the FAU framework. Finally, in steamed zeolite ferrierite with FER topology the extraframework aluminum species were trapped and therefore not accessible for phosphoric acid; hence, no AlPO4 phase could be formed within the structure. Therefore, the parameters to be taken into account in AlPO4 synthesis are the framework Si/Al ratio, stability of framework aluminum, pore dimensionality and accessibility of extraframework aluminum species.

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“…27,[87][88][89][90][91] In their detailed examination of aluminosilicate minerals, Li and coworkers developed assignments by comparing Al K-edge and Si K-edge spectra and using MO calculations of the AlO6 9-cluster.…”

Section: Figure 4 Al K-edge Xas Of Al Metal (Black Circles) Comparedmentioning

confidence: 99%

Chemical and Morphological Inhomogeneity of Aluminum Metal and Oxides from Soft X-ray Spectromicroscopy

Altman

Pemmaraju²,

Alayoǧlu³

et al. 2017

Inorg. Chem.

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ABSTRACT. Oxygen and aluminum K-edge X-ray absorption spectroscopy (XAS), imaging from a scanning transmission X-ray microscope (STXM), and first principles calculations were used to probe the composition and morphology of bulk aluminum metal, α-and γ-Al2O3, and several types of aluminum nanoparticles. The imaging results agreed with earlier transmission electron microscopy studies that showed a 2 to 5 nm thick layer of Al2O3 on all the Al surfaces. Spectral interpretations were guided by examination of the calculated transition energies, which agreed well with the spectroscopic measurements. Features observed in the experimental O and Al K-edge XAS were used to determine the chemical structure and phase of the Al2O3 on the aluminum surfaces. For unprotected 18 and 100 nm Al nanoparticles, this analysis revealed an oxide layer that was similar to γ-Al2O3 and comprised of both tetrahedral and octahedral Al coordination sites. For oleic-acid protected Al nanoparticles, only tetrahedral Al oxide coordination sites were observed.The results were correlated to trends in the reactivity of the different materials, which suggests that the structures of different Al2O3 layers have an important role in the accessibility of the underlying Al metal towards further oxidation.Combined, the Al K-edge XAS and STXM results provided detailed chemical information that was not obtained from powder X-ray diffraction or imaging from a transmission electron microscope.

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3D Nanoscale Chemical Imaging of the Distribution of Aluminum Coordination Environments in Zeolites with Soft X‐Ray Microscopy

Cited by 34 publications

References 31 publications

Integrated Transmission Electron and Single‐Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

Integrated Transmission Electron and Single‐Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

Aluminum-Phosphate Binder Formation in Zeolites as Probed with X-ray Absorption Microscopy

Chemical and Morphological Inhomogeneity of Aluminum Metal and Oxides from Soft X-ray Spectromicroscopy

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