High‐Resolution Single‐Molecule Fluorescence Imaging of Zeolite Aggregates within Real‐Life Fluid Catalytic Cracking Particles

Ristanović, Zoran; Kerssens, Marleen M.; Kubarev, A. V.; Hendriks, Frank C.; Dedecker, Peter; Hofkens, Johan; Roeffaers, Maarten B. J.; Weckhuysen, Bert M.

doi:10.1002/anie.201410236

Cited by 89 publications

(75 citation statements)

References 36 publications

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“…It was found that the average size of a zeolite aggregate domain for the fresh FCC catalyst particle (0.70 μm 2 , Figure a) is significantly larger than that of the ECAT1 (0.52 μm 2 , Figure b) and ECAT2 (0.55 μm 2 , Figure c) particles. The observed zeolite size distributions are consistent with other studies where conventional and single‐molecule confocal fluorescence microscopy were used to study FCC catalysts containing ZSM‐5 zeolites, thus supporting the use of La as a specific marker for pinpointing individual zeolite domains in a catalyst matrix …”

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confidence: 87%

Visualizing Dealumination of a Single Zeolite Domain in a Real‐Life Catalytic Cracking Particle

et al. 2016

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Fluid catalytic cracking (FCC) catalysts play acentral role in the chemical conversion of crude oil fractions. Using scanning transmission X-raym icroscopy( STXM) we investigate the chemistry of one fresh and two industrially deactivated (ECAT) FCC catalysts at the single zeolite domain level. Spectro-microscopic data at the Fe L 3 ,L aM 5 ,a nd Al K X-ray absorption edges reveal differing levels of deposited Fe on the ECAT catalysts corresponding with an overall loss in tetrahedral Al within the zeolite domains.U sing La as alocalization marker,wehave developed anovel methodology to map the changing Al distribution of single zeolite domains within real-life FCC catalysts.I tw as found that significant changes in the zeolited omain sized istributions as well as the loss of Al from the zeolite framework occur.F urthermore, inter-a nd intraparticle heterogeneities in the dealumination process were observed, revealing the complex interplay between metal-mediated pore accessibility loss and zeolite dealumination.

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Section: Figuresupporting

confidence: 87%

Visualizing Dealumination of a Single Zeolite Domain in a Real‐Life Catalytic Cracking Particle

et al. 2016

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“…Alternatively, fluorescence microscopy, combined with fluorogenic probe molecules, enables the localization of single catalytic turnovers, and thus the location of accessible Brønsted acid sites, with up to 20 nanometer resolution. By accumulating these turnovers into catalytic activity maps, as done in nanometer accuracy by stochastic chemical reactions (NASCA) microscopy, the catalyst performance can be assessed at the nanoscale Hence, such measurements directly reveal the combined effect of acidity and accessibility, as these stochastic catalytic turnovers are localized while occurring on accessible acid sites.…”

Section: Figurementioning

confidence: 99%

Assessing Inter and Intra‐particle Heterogeneity in Alumina‐poor H‐ZSM‐5 Zeolites

et al. 2017

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We reveal the presence of significant variations in Brønsted catalytic activity within and between individual H-ZSM-5 zeolite crystals. Fluorescence microscopy in combinationw ith a fluorogenic probe was used to resolve the catalytic activity at the nanoscale. The observed variations in catalytic activity could be directly linked to structural parameters and crystal morphology observed in scanninge lectron microscopy and by specifically stainingc rystal defects. The obtained resultsa re directly comparedw ith ensemblea veraged information from techniques such as pyridine IR spectroscopy and nitrogen physisorption, typically used to characterize acid zeolites. The inter-and intra-particle heterogeneities resolved by the employed fluorescence approach remainu naddressed by bulk characterization. Our experimental resultsr elate the heterogeneous catalytic activity to variation in both the Si/Al ratio and mesoporosity inducedd uring the zeolite synthesis.The preparation of zeolite-based industrial catalysts usually involves mixingt he zeolitesw ith silicaa nd or aluminab inders in order to dilute the zeolite properties and to obtain the desired throughput. [1][2][3] During this process it is assumed that the zeolite crystalsthemselves are homogeneous in nature, [2,4,5] that is, only small variations in properties between the zeolite crystals in ab atch exist. However,i fthis assumption is wrong and large variations in, for example, acid site density are present, parts of the shaped catalystc ould become more active than others,r esulting in undesired coke formation and thus al oss in catalystactivity and lifetime. [4,6,7] Twop arameters impacting catalyst activity are the number and strength of acid sites present in az eolite. These are directly relatedt ot he framework Al content, [8,9] hence Al determination is often used to assess zeolite acidity.S everalt echniques can be used to determine the Si/Al ratio, yielding powder averaged information, for example, elemental analysisu sing inductive coupled plasma (ICP), [10,11] magic angle spinning (MAS) 29 Si and 27 Al NMR, [8,12] laser induced break down spectroscopy (LIBS), [13] X-ray photon electron spectroscopy (XPS) [12,14] and time of flight-secondary ion mass spectrometry (TOF-SIMS). [15,16] All of theset echniques lead to the determination of the 'bulk" scale acidity and some are even able to obtain single crystal information given that crystal sizes and aluminum content are sufficiently large; [17] for example, single crystal X-ray diffraction [17,18] and energy dispersive X-ray spectroscopy (EDX) coupled to electron microscopy potentially with focused-ion-beam milling. [14,19] In summary,t he acidic properties of zeolitesa re often deduced indirectly from the aluminum content.F urther,n oi nformation regarding site accessibility is obtained in these results. Direct measurements of acid site density and strengtha re possible via temperature programmed desorption (TPD) [8,14,20] and infrared- [2,21,22] or Raman spectroscopy [23] using basic probe molecules such...

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“…The hyperspectral information gained from the TEFL maps revealed a spatial distribution of Brønsted acidity within the individual zeolite domains in different regions of the catalyst particle. We have also shown that sectioning of catalyst particles into thin layers is an effective strategy to investigate zeolite acidity in the central regions of the spherical particles, which are not easily accessible by super‐resolution fluorescence microscopy . These results demonstrate that TEFL can become a powerful and sensitive characterization tool to investigate single catalyst particles and reveal inter‐ and intra‐particle chemical variations with nanoscale spatial resolution.…”

Section: Figurementioning

confidence: 80%

Nanoscale Chemical Imaging of a Single Catalyst Particle with Tip‐Enhanced Fluorescence Microscopy

et al. 2018

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Determining the active site in real‐life solid catalysts remains an intellectual challenge and is crucial for exploring the road towards their rational design. In recent years various micro‐spectroscopic methods have revealed valuable structure‐activity data at the level of a single catalyst particle, even under reaction conditions. Herein, we introduce Tip‐Enhanced FLuorescence (TEFL) microscopy as a novel and versatile characterization tool for catalysis research. This has been achieved using a Fluid Catalytic Cracking (FCC) catalyst as showcase material. Thin sectioning of industrially used FCC particles together with selective staining of Brønsted acidity has enabled high‐resolution TEFL mapping of different catalyst regions. Hyperspectral information gained via TEFL microscopy reveals a spatial distribution of Brønsted acidity within individual zeolite domains in different regions of the FCC catalyst particle. Comparison of TEFL measurements from different FCC particles showed significant intra‐ and inter‐particle heterogeneities both in zeolite domain size and chemical reactivity.

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High‐Resolution Single‐Molecule Fluorescence Imaging of Zeolite Aggregates within Real‐Life Fluid Catalytic Cracking Particles

Cited by 89 publications

References 36 publications

Visualizing Dealumination of a Single Zeolite Domain in a Real‐Life Catalytic Cracking Particle

Visualizing Dealumination of a Single Zeolite Domain in a Real‐Life Catalytic Cracking Particle

Assessing Inter and Intra‐particle Heterogeneity in Alumina‐poor H‐ZSM‐5 Zeolites

Nanoscale Chemical Imaging of a Single Catalyst Particle with Tip‐Enhanced Fluorescence Microscopy

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