Architecture‐Dependent Distribution of Mesopores in Steamed Zeolite Crystals as Visualized by FIB‐SEM Tomography

Karwacki, Łukasz; Winter, D. A. Matthijs de; Aramburo, Luis R.; Lebbink, Misjaël N.; Post, Jan Andries; Drury, M. R.; Weckhuysen, Bert M.

doi:10.1002/anie.201006031

Cited by 68 publications

(68 citation statements)

References 35 publications

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“…165,180,181 Ryoo et al reported the synthesis of mesoporous zeolites using organosilane surfactants (OSS) as templates. 165,180,181 Ryoo et al reported the synthesis of mesoporous zeolites using organosilane surfactants (OSS) as templates.…”

Section: Fib-semmentioning

confidence: 99%

“…165,181 Three distinct regions of the parent (ZSM-5-P) and steamed (ZSM-5-ST) ZSM-5 crystal were examined, corresponding to the parts of the crystal with straight and sinusoidal channels open to the surface, and the part where straight channels are covered by the 901 rotational barrier. 165,181 Three distinct regions of the parent (ZSM-5-P) and steamed (ZSM-5-ST) ZSM-5 crystal were examined, corresponding to the parts of the crystal with straight and sinusoidal channels open to the surface, and the part where straight channels are covered by the 901 rotational barrier.…”

Section: Fib-semmentioning

confidence: 99%

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Tailoring and visualizing the pore architecture of hierarchical zeolites

et al. 2015

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Recently the concept of hierarchical zeolites invoked more explicit attention to enhanced accessibility of zeolites. By realizing additional meso-/macroporosity with the intrinsic microporosity of zeolites, a hierarchical pore system arises which facilitates mass transport while maintaining the zeolite shape selectivity. A great number of synthesis strategies have been developed for tailoring the pore architecture of hierarchical zeolites. In this review, we give a general overview of different synthesis methods for introduction of additional porosity. Advantages and limitations of these different synthesis approaches are addressed. The assessment of pore structure is essential to build the link between the zeolite pore structure and its functionality. A variety of 2D and 3D microscopy techniques are crucial to visualize the hierarchical pore structure, providing unique and comprehensive information that, however, should be linked to the results of bulk characterization techniques as much as possible. The microscopy techniques are classified and discussed according to the different probes used, such as optical light, X-rays and electrons. Representative work is reviewed to elucidate the capability of each technique and their drawbacks.

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Section: Fib-semmentioning

confidence: 99%

Section: Fib-semmentioning

confidence: 99%

Tailoring and visualizing the pore architecture of hierarchical zeolites

et al. 2015

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“…[13][14][15][16] Among the latter approaches, dealumination by steaming has become a cheap and efficient way to simultaneously modify the topological and acidic properties of zeolites. 17,18 To optimize the variation of zeolite characteristics, an in-depth understanding of the physicochemical processes that determine the catalytic properties of zeolite materials is needed. Such information can be obtained in some cases by performing a suitable probe reaction in combination with appropriate spectroscopic methods, such as UV-Vis and (confocal) fluorescence micro-spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Styrene oligomerization as a molecular probe reaction for Brønsted acidity at the nanoscale

Aramburo

Wirick

Miedema

et al. 2012

Phys. Chem. Chem. Phys.

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The Brønsted acid-catalyzed oligomerization of 4-fluorostyrene has been studied on a series of H-ZSM-5 zeolite powders, steamed under different conditions, with a combination of UV-Vis micro-spectroscopy and Scanning Transmission X-ray Microscopy (STXM). UV-Vis microspectroscopy and STXM have been used to monitor the relative formation of cyclic and linear dimeric carbocations as a function of the steaming post-treatment (i.e., parent vs. steaming at 600, 700 and 800 1C). It was found that the UV-Vis band intensity ratios of linear to cyclic dimeric species increase from 0.79 (parent H-ZSM-5) over 1.41 (H-ZSM-5 steamed at 600 1C) and 1.88 (H-ZSM-5 steamed at 700 1C) to 2.33 (H-ZSM-5 steamed at 800 1C). STXM confirms this trend in reaction product selectivity, as the relative intensities of the transitions attributed to the presence of the cyclic dimer in the carbon K-edge spectra decrease with increasing severity of the steaming post-treatment. Furthermore, STXM reveals spatial heterogeneities in reaction product formation within the H-ZSM-5 zeolite powders at the nanoscale. More specifically, a shrinking carbon core-shell distribution was detected within the zeolite aggregates, in which the relative amount of cyclic dimeric species is higher in the core relative to the shell of the zeolite aggregate and the relative amount of cyclic dimeric species in the zeolite core gradually decreases with increasing severity of the steaming post-treatment. These differences are rationalized in terms of spatial differences in Brønsted acidity within H-ZSM-5 zeolite powders as well as by changes in the formation process of linear and dimeric carbocations within H-ZSM-5 micro-and mesopores.

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“…Quantification of MFI/MEL contribution is not a trivial task [38,39], and it is usually obtained via electron microscopy methods [40,41]. Moreover, it should also be mentioned that even the ZSM-5 presents intergrowth [42]. An alternative quantification approach, despite a larger experimental error when compared with microscopy tools, consists of describing the final framework of the ZSM-5/11 as blocks of MFI and MEL units randomly dispersed [43], and therefore estimating the contribution of MFI and MEL structure from the Xray powder patterns can be performed.…”

Section: Resultsmentioning

confidence: 99%