1
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Carl S, Will J, Madubuko N, Götz A, Przybilla T, Wu M, Raman N, Wirth J, Taccardi N, Zubiri BA, Haumann M, Wasserscheid P, Spiecker E. Structural Evolution of GaO x-Shell and Intermetallic Phases in Ga-Pt Supported Catalytically Active Liquid Metal Solutions. J Phys Chem Lett 2024; 15:4711-4720. [PMID: 38657124 DOI: 10.1021/acs.jpclett.3c03494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
We present a comprehensive scale-bridging characterization approach for supported catalytically active liquid metal solutions (SCALMS) which combines lab-based X-ray microscopy, nano X-ray computed tomography (nano-CT), and correlative analytical transmission electron microscopy. SCALMS catalysts consist of low-melting alloy particles and have demonstrated high catalytic activity, selectivity, and long-term stability in propane dehydrogenation (PDH). We established an identical-location nano-CT workflow which allows us to reveal site-specific changes of Ga-Pt SCALMS before and after PDH. These observations are complemented by analytical transmission electron microscopy investigations providing information on the structure, chemical composition, and phase distribution of individual SCALMS particles. Key findings of this combined microscopic approach include (i) structural evolution of the SCALMS particles' GaOx shell, (ii) Pt segregation toward the oxide shell leading to the formation of Ga-Pt intermetallic phases, and (iii) cracking of the oxide shell accompanied by the release of liquid Ga-Pt toward the porous support.
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Affiliation(s)
- S Carl
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - J Will
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - N Madubuko
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - A Götz
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - T Przybilla
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - M Wu
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - N Raman
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - J Wirth
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - N Taccardi
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - B Apeleo Zubiri
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - M Haumann
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
- Research Centre for Synthesis and Catalysis, Department of Chemistry, University of Johannesburg, P.O. Box 524, 2006 Auckland Park, South Africa
| | - P Wasserscheid
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
- Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Forschungszentrum Jülich GmbH, Egerlandstr. 3, 91058 Erlangen, Germany
| | - E Spiecker
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
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2
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Werny MJ, Meirer F, Weckhuysen BM. Visualizing the Structure, Composition and Activity of Single Catalyst Particles for Olefin Polymerization and Polyolefin Decomposition. Angew Chem Int Ed Engl 2024; 63:e202306033. [PMID: 37782261 DOI: 10.1002/anie.202306033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 09/29/2023] [Accepted: 10/02/2023] [Indexed: 10/03/2023]
Abstract
The structural and morphological characterization of individual catalyst particles for olefin polymerization, as well as for the reverse process of polyolefin decomposition, can provide an improved understanding for how these catalyst materials operate under relevant reaction conditions. In this review, we discuss an emerging analytical toolbox of 2D and 3D chemical imaging techniques that is suitable for investigating the chemistry and reactivity of related catalyst systems. While synchrotron-based X-ray microscopy still provides unparalleled spatial resolutions in 2D and 3D, a number of laboratory-based techniques, most notably focused ion beam-scanning electron microscopy, confocal fluorescence microscopy, infrared photoinduced force microscopy and laboratory-based X-ray nano-computed tomography, have helped to significantly expand the arsenal of analytical tools available to scientists in heterogeneous catalysis and polymer science. In terms of future research, the review outlines the role and impact of in situ and operando (spectro-)microscopy experiments, involving sophisticated reactors as well as online reactant and product analysis, to obtain real-time information on the formation, decomposition, and mobility of polymer phases within single catalyst particles. Furthermore, the potential of fluorescence microscopy, X-ray microscopy and optical microscopy is highlighted for the high-throughput characterization of olefin polymerization and polyolefin decomposition catalysts. By combining these chemical imaging techniques with, for example, chemical staining methodologies, selective probe molecules as well as particle sorting approaches, representative structure-activity relationships can be derived at the level of single catalyst particles.
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Affiliation(s)
- Maximilian J Werny
- Inorganic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry and Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG Utrecht, The Netherlands
- Dutch Polymer Institute (DPI), P.O. Box 902, 5600, AX Eindhoven, The Netherlands
| | - Florian Meirer
- Inorganic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry and Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG Utrecht, The Netherlands
| | - Bert M Weckhuysen
- Inorganic Chemistry and Catalysis, Institute for Sustainable and Circular Chemistry and Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG Utrecht, The Netherlands
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3
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Bian J, Wang B, Niu X, Zhao H, Ling H, Ju F. Migration and emission characteristics of metal pollutants in fluid catalytic cracking (FCC) process. JOURNAL OF HAZARDOUS MATERIALS 2024; 462:132778. [PMID: 37844495 DOI: 10.1016/j.jhazmat.2023.132778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/01/2023] [Accepted: 10/11/2023] [Indexed: 10/18/2023]
Abstract
Fluid catalytic cracking (FCC) is the core unit for heavy oil conversion in refineries. In the FCC process, the metal contaminants from the feedstock are deposited on the catalysts, causing catalyst deactivation and metal particulate matter (PM) emission. However, the migration and emission characteristics of metal pollutants in FCC units are still unclear. Here, the stack tests of three FCC units were carried out to monitor metal PM emissions, and the metal contents of the feedstock oil and spent catalyst were detected. For the metal migration from the feedstock to the catalysts, Ni, Fe, and V have high concentrations and migration rates while other metals perform much lower. The metal distribution on the spent catalysts profoundly determines the metal mobility to the flue gas and the regeneration process affects the catalyst attrition, leading to metal PM emissions discrepancy. The migration rate and emission concentration of V in the deeper layers of the catalysts are much lower than those of Ni at the particle's exterior. Finally, the stack data was used to calculate the emission factors and ratio factors of the metal PM. This work is expected to advance metal migration cognition and metal pollutants emissions estimation in FCC units.
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Affiliation(s)
- Jiawei Bian
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Bohan Wang
- Key Laboratory of Specially Functional Polymeric Materials and Related Technology of the Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Ximing Niu
- Shanghai Research Institute of Chemical Industry CO., LTD, Shanghai 200333, China
| | - Hai Zhao
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Hao Ling
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Feng Ju
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China; Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, the Netherlands.
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4
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Dery S, Friedman B, Shema H, Gross E. Mechanistic Insights Gained by High Spatial Resolution Reactivity Mapping of Homogeneous and Heterogeneous (Electro)Catalysts. Chem Rev 2023; 123:6003-6038. [PMID: 37037476 PMCID: PMC10176474 DOI: 10.1021/acs.chemrev.2c00867] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
The recent development of high spatial resolution microscopy and spectroscopy tools enabled reactivity analysis of homogeneous and heterogeneous (electro)catalysts at previously unattainable resolution and sensitivity. These techniques revealed that catalytic entities are more heterogeneous than expected and local variations in reaction mechanism due to divergences in the nature of active sites, such as their atomic properties, distribution, and accessibility, occur both in homogeneous and heterogeneous (electro)catalysts. In this review, we highlight recent insights in catalysis research that were attained by conducting high spatial resolution studies. The discussed case studies range from reactivity detection of single particles or single molecular catalysts, inter- and intraparticle communication analysis, and probing the influence of catalysts distribution and accessibility on the resulting reactivity. It is demonstrated that multiparticle and multisite reactivity analyses provide unique knowledge about reaction mechanism that could not have been attained by conducting ensemble-based, averaging, spectroscopy measurements. It is highlighted that the integration of spectroscopy and microscopy measurements under realistic reaction conditions will be essential to bridge the gap between model-system studies and real-world high spatial resolution reactivity analysis.
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Affiliation(s)
- Shahar Dery
- Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem 91904, Israel
| | - Barak Friedman
- Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem 91904, Israel
| | - Hadar Shema
- Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem 91904, Israel
| | - Elad Gross
- Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University, Jerusalem 91904, Israel
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5
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Huhn S, Lohse LM, Lucht J, Salditt T. Fast algorithms for nonlinear and constrained phase retrieval in near-field X-ray holography based on Tikhonov regularization. OPTICS EXPRESS 2022; 30:32871-32886. [PMID: 36242340 DOI: 10.1364/oe.462368] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 08/02/2022] [Indexed: 06/16/2023]
Abstract
Based on phase retrieval, lensless coherent imaging and in particular holography offers quantitative phase and amplitude images. This is of particular importance for spectral ranges where suitable lenses are challenging, such as for hard x-rays. Here, we propose a phase retrieval approach for inline x-ray holography based on Tikhonov regularization applied to the full nonlinear forward model of image formation. The approach can be seen as a nonlinear generalization of the well-established contrast transfer function (CTF) reconstruction method. While similar methods have been proposed before, the current work achieves nonlinear, constrained phase retrieval at competitive computation times. We thus enable high-throughput imaging of optically strong objects beyond the scope of CTF. Using different examples of inline holograms obtained from illumination by a x-ray waveguide-source, we demonstrate superior image quality even for samples which do not obey the assumption of a weakly varying phase. Since the presented approach does not rely on linearization, we expect it to be well suited also for other probes such as visible light or electrons, which often exhibit strong phase interaction.
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6
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Das S, Pashminehazar R, Sharma S, Weber S, Sheppard TL. New Dimensions in Catalysis Research with Hard X‐Ray Tomography. CHEM-ING-TECH 2022. [DOI: 10.1002/cite.202200082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Srashtasrita Das
- Karlsruhe Institute of Technology Institute for Chemical Technology and Polymer Chemistry Engesserstraße 18 76131 Karlsruhe Germany
| | - Reihaneh Pashminehazar
- Karlsruhe Institute of Technology Institute for Chemical Technology and Polymer Chemistry Engesserstraße 18 76131 Karlsruhe Germany
| | - Shweta Sharma
- Karlsruhe Institute of Technology Institute for Chemical Technology and Polymer Chemistry Engesserstraße 18 76131 Karlsruhe Germany
| | - Sebastian Weber
- Karlsruhe Institute of Technology Institute for Chemical Technology and Polymer Chemistry Engesserstraße 18 76131 Karlsruhe Germany
- Karlsruhe Institute of Technology Institute of Catalysis Research and Technology Hermann-von-Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Thomas L. Sheppard
- Karlsruhe Institute of Technology Institute for Chemical Technology and Polymer Chemistry Engesserstraße 18 76131 Karlsruhe Germany
- Karlsruhe Institute of Technology Institute of Catalysis Research and Technology Hermann-von-Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen Germany
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7
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Wennmacher JTC, Mahmoudi S, Rzepka P, Sik Lee S, Gruene T, Paunović V, van Bokhoven JA. Electron Diffraction Enables the Mapping of Coke in ZSM-5 Micropores Formed during Methanol-to-Hydrocarbons Conversion. Angew Chem Int Ed Engl 2022; 61:e202205413. [PMID: 35513343 PMCID: PMC9401574 DOI: 10.1002/anie.202205413] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Indexed: 12/29/2022]
Abstract
Unveiling the coke formation in zeolites is an essential prerequisite for tackling the deactivation of these catalysts in the transformations of hydrocarbons. Herein, we present the direct mapping of coke in the micropores of ZSM‐5 catalysts used in methanol‐to‐hydrocarbons conversion by single‐crystal electron diffraction analysis. The latter technique revealed a polycyclic aromatic structure along the straight channel, wherein the high‐quality data permit refinement of its occupancy to about 40 %. These findings were exploited to analyze the evolution of micropore coke during the reaction. Herein, coke‐associated signals, which correlate with the activity loss, indicate that the nucleation of coke commences in the intersections of sinusoidal and straight channels, while the formation of coke in the straight pores occurs in the late stages of deactivation. The findings uncover an attractive method for analyzing coke deposition in the micropore domain.
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Affiliation(s)
- Julian T C Wennmacher
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.,Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland
| | - Soheil Mahmoudi
- Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 42, 1090, Vienna, Austria.,Vienna Doctoral School in Chemistry (DoSChem), University of Vienna, Währinger Strasse 42, 1090, Vienna, Austria
| | - Przemyslaw Rzepka
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.,Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland
| | - Sung Sik Lee
- Scientific Center of Optical and Electron Microscopy, ETH Zurich, Otto-Stern-Weg 3, 8093, Zurich, Switzerland
| | - Tim Gruene
- Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 42, 1090, Vienna, Austria
| | - Vladimir Paunović
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.,Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland
| | - Jeroen A van Bokhoven
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.,Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland
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8
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Electron Diffraction Enables the Mapping of Coke in ZSM‐5 Micropores Formed during Methanol‐to‐Hydrocarbons Conversion. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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9
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Prokop M, Vesely M, Capek P, Paidar M, Bouzek K. High-temperature PEM fuel cell electrode catalyst layers part 1: Microstructure reconstructed using FIB-SEM tomography and its calculated effective transport properties. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.140133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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10
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Sala S, Zhang Y, De La Rosa N, Dreier T, Kahnt M, Langer M, Dahlin LB, Bech M, Villanueva-Perez P, Kalbfleisch S. Dose-efficient multimodal microscopy of human tissue at a hard X-ray nanoprobe beamline. JOURNAL OF SYNCHROTRON RADIATION 2022; 29:807-815. [PMID: 35511013 PMCID: PMC9070709 DOI: 10.1107/s1600577522001874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/17/2022] [Indexed: 06/14/2023]
Abstract
X-ray fluorescence microscopy performed at nanofocusing synchrotron beamlines produces quantitative elemental distribution maps at unprecedented resolution (down to a few tens of nanometres), at the expense of relatively long measuring times and high absorbed doses. In this work, a method was implemented in which fast low-dose in-line holography was used to produce quantitative electron density maps at the mesoscale prior to nanoscale X-ray fluorescence acquisition. These maps ensure more efficient fluorescence scans and the reduction of the total absorbed dose, often relevant for radiation-sensitive (e.g. biological) samples. This multimodal microscopy approach was demonstrated on human sural nerve tissue. The two imaging modes provide complementary information at a comparable resolution, ultimately limited by the focal spot size. The experimental setup presented allows the user to swap between them in a flexible and reproducible fashion, as well as to easily adapt the scanning parameters during an experiment to fine-tune resolution and field of view.
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Affiliation(s)
- Simone Sala
- MAX IV Laboratory, Lund University, 22100 Lund, Sweden
| | - Yuhe Zhang
- Division of Synchrotron Radiation Research and NanoLund, Department of Physics, Lund University, 22100 Lund, Sweden
| | - Nathaly De La Rosa
- Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, 22185 Lund, Sweden
| | - Till Dreier
- Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, 22185 Lund, Sweden
- Excillum AB, 16440 Kista, Sweden
| | - Maik Kahnt
- MAX IV Laboratory, Lund University, 22100 Lund, Sweden
| | - Max Langer
- Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, 69621 Villeurbanne, France
| | - Lars B. Dahlin
- Department of Translational Medicine – Hand Surgery, Lund University, Malmö, Sweden
- Department of Hand Surgery, Skåne University Hospital, Malmö, Sweden
| | - Martin Bech
- Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, 22185 Lund, Sweden
| | - Pablo Villanueva-Perez
- Division of Synchrotron Radiation Research and NanoLund, Department of Physics, Lund University, 22100 Lund, Sweden
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11
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Abstract
Catalysis is at the core of chemistry and has been essential to make all the goods surrounding us, including fuels, coatings, plastics and other functional materials. In the near future, catalysis will also be an essential tool in making the shift from a fossil-fuel-based to a more renewable and circular society. To make this reality, we have to better understand the fundamental concept of the active site in catalysis. Here, we discuss the physical meaning - and deduce the validity and, therefore, usefulness - of some common approaches in heterogeneous catalysis, such as linking catalyst activity to a 'turnover frequency' and explaining catalytic performance in terms of 'structure sensitivity' or 'structure insensitivity'. Catalytic concepts from the fields of enzymatic and homogeneous catalysis are compared, ultimately realizing that the struggle that one encounters in defining the active site in most solid catalysts is likely the one we must overcome to reach our end goal: tailoring the precise functioning of the active sites with respect to many different parameters to satisfy our ever-growing needs. This article ends with an outlook of what may become feasible within the not-too-distant future with modern experimental and theoretical tools at hand.
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12
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Harte Röntgen‐Nanotomographie zur 3D‐Analyse der Verkokung in Nickel‐basierten Katalysatoren. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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13
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Weber S, Batey D, Cipiccia S, Stehle M, Abel KL, Gläser R, Sheppard TL. Hard X-Ray Nanotomography for 3D Analysis of Coking in Nickel-Based Catalysts. Angew Chem Int Ed Engl 2021; 60:21772-21777. [PMID: 34339595 PMCID: PMC8518723 DOI: 10.1002/anie.202106380] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/13/2021] [Indexed: 12/24/2022]
Abstract
Understanding catalyst deactivation by coking is crucial for knowledge-based catalyst and process design in reactions with carbonaceous species. Post-mortem analysis of catalyst coking is often performed by bulk characterization methods. Here, hard X-ray ptychographic computed tomography (PXCT) was used to study Ni/Al2 O3 catalysts for CO2 methanation and CH4 dry reforming after artificial coking treatment. PXCT generated quantitative 3D maps of local electron density at ca. 80 nm resolution, allowing to visualize and evaluate the severity of coking in entire catalyst particles of ca. 40 μm diameter. Coking was primarily revealed in the nanoporous solid, which was not detectable in resolved macropores. Coke formation was independently confirmed by operando Raman spectroscopy. PXCT is highlighted as an emerging characterization tool for nanoscale identification, co-localization, and potentially quantification of deactivation phenomena in 3D space within entire catalyst particles.
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Affiliation(s)
- Sebastian Weber
- Institute for Chemical Technology and Polymer ChemistryKarlsruhe Institute of Technology (KIT)Engesserstr. 2076131KarlsruheGermany
- Institute of Catalysis Research and TechnologyKarlsruhe Institute of Technology (KIT)Hermann-von-Helmholtz-Platz 176344Eggenstein-LeopoldshafenGermany
| | - Darren Batey
- Diamond Light SourceHarwell Science and Innovation CampusFermi AveDidcotOX11 0DEUK
| | - Silvia Cipiccia
- Dept. of Medical Physics & Biomedical EngineeringUniversity College LondonMalet Place, Gower StreetLondonWC1E 6BTUK
| | - Matthias Stehle
- Institute for Chemical Technology and Polymer ChemistryKarlsruhe Institute of Technology (KIT)Engesserstr. 2076131KarlsruheGermany
| | - Ken L. Abel
- Institute of Chemical TechnologyUniversität LeipzigLinnéstr. 304103LeipzigGermany
| | - Roger Gläser
- Institute of Chemical TechnologyUniversität LeipzigLinnéstr. 304103LeipzigGermany
| | - Thomas L. Sheppard
- Institute for Chemical Technology and Polymer ChemistryKarlsruhe Institute of Technology (KIT)Engesserstr. 2076131KarlsruheGermany
- Institute of Catalysis Research and TechnologyKarlsruhe Institute of Technology (KIT)Hermann-von-Helmholtz-Platz 176344Eggenstein-LeopoldshafenGermany
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14
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Bossers KW, Valadian R, Garrevoet J, van Malderen S, Chan R, Friederichs N, Severn J, Wilbers A, Zanoni S, Jongkind MK, Weckhuysen BM, Meirer F. Heterogeneity in the Fragmentation of Ziegler Catalyst Particles during Ethylene Polymerization Quantified by X-ray Nanotomography. JACS AU 2021; 1:852-864. [PMID: 34240080 PMCID: PMC8243319 DOI: 10.1021/jacsau.1c00130] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Indexed: 05/03/2023]
Abstract
Ziegler-type catalysts are the grand old workhorse of the polyolefin industry, yet their hierarchically complex nature complicates polymerization activity-catalyst structure relationships. In this work, the degree of catalyst framework fragmentation of a high-density polyethylene (HDPE) Ziegler-type catalyst was studied using ptychography X-ray-computed nanotomography (PXCT) in the early stages of ethylene polymerization under mild reaction conditions. An ensemble consisting of 434 fully reconstructed ethylene prepolymerized Ziegler catalyst particles prepared at a polymer yield of 3.4 g HDPE/g catalyst was imaged. This enabled a statistical route to study the heterogeneity in the degree of particle fragmentation and therefore local polymerization activity at an achieved 3-D spatial resolution of 74 nm without requiring invasive imaging tools. To study the degree of catalyst fragmentation within the ensemble, a fragmentation parameter was constructed based on a k-means clustering algorithm that relates the quantity of polyethylene formed to the average size of the spatially resolved catalyst fragments. With this classification method, we have identified particles that exhibit weak, moderate, and strong degrees of catalyst fragmentation, showing that there is a strong heterogeneity in the overall catalyst particle fragmentation and thus polymerization activity within the entire ensemble. This hints toward local mass transfer limitations or other deactivation phenomena. The methodology used here can be applied to all polyolefin catalysts, including metallocene and the Phillips catalysts to gain statistically relevant fundamental insights in the fragmentation behavior of an ensemble of catalyst particles.
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Affiliation(s)
- Koen W. Bossers
- Inorganic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Roozbeh Valadian
- Inorganic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Jan Garrevoet
- Photon
Science at Deutsches Elektronen-Synchrotron DESY, Hamburg 22603, Germany
| | - Stijn van Malderen
- Photon
Science at Deutsches Elektronen-Synchrotron DESY, Hamburg 22603, Germany
| | - Robert Chan
- SABIC, P.O. Box 319, 6160
AH Geleen, The Netherlands
| | | | - John Severn
- DSM
Materials Science Center, 6167 RD Geleen, The Netherlands
| | - Arnold Wilbers
- DSM
Materials Science Center, 6167 RD Geleen, The Netherlands
| | - Silvia Zanoni
- Inorganic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Maarten K. Jongkind
- Inorganic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Bert M. Weckhuysen
- Inorganic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Florian Meirer
- Inorganic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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