Engineering operando methodology: Understanding catalysis in time and space

Portela, Raquel; Pérez-Ferreras, Susana; Serrano-Lotina, Ana; Bañares, Miguel Á.

doi:10.1007/s11705-018-1740-9

Cited by 40 publications

(31 citation statements)

References 138 publications

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“…Porous frameworks seem to be the ideal model materials for such a development due to their modular character and multivariate construction principles 51,52 . These developments may significantly profit from advanced techniques and understanding of spatiotemporal phenomena in catalysis [72][73][74] .…”

Section: Current Understanding Of Dynamic Phenomena In Metalorganic Fmentioning

confidence: 99%

Four-dimensional metal-organic frameworks

et al. 2020

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Recognising timescale as an adjustable dimension in porous solids provides a new perspective to develop novel four-dimensional framework materials. The deliberate design of three-dimensional porous framework architectures is a developed field; however, the understanding of dynamics in open frameworks leaves a number of key questions unanswered: What factors determine the spatiotemporal evolution of deformable networks? Can we deliberately engineer the response of dynamic materials along a time-axis? How can we engineer energy barriers for the selective recognition of molecules? Answering these questions will require significant methodological development to understand structural dynamics across a range of time and length scales. P orous framework materials offer outstanding functionality due to their wide range of tuneable building blocks and ultrahigh porosity 1-5. The integration of functions, such as chemisorptive, redox, optically or catalytically active centers, encapsulated drugs, enzymes, nanoparticles, and more, has led to the discovery of metal-organic framework (MOF) applications in gas separation, CO 2 sequestration, gas storage, catalysis, optics, and sensing, and a roadmap for integration into electronic systems has even been proposed 6-12. The chemistry of three-dimensional (3D) porous framework materials, connecting nodes and linkers through a variety of chemical bonds is enormously rich 13,14. While decades ago, rationalization was aided by topology analysis and isoreticular expansion 15,16 , in the age of digitalization computer-aided design plays a crucial role in predicting millions of new 3D structures and their properties 17-19. The serendipitous discovery of an adsorption induced structural transformation in a network nowadays termed ELM-11 20 stimulated researchers and laid the foundations for exploring novel dynamic phenomena in porous frameworks. Like enzymes, structural changes are stimulated by guest molecules intruding into the porous frameworks leading to macroscopic volume changes of up to 200-300%. The adaptive change of pore size is a fascinating feature, but a selectivity comparable to that of enzymes has not been reached yet. Emerging applications of adaptive porous materials Porosity switching in the crystalline solid state represents a unique phenomenon observed only in a limited number of porous materials 21-25. This flexibility was predicted in 1998 for MOFs by Kitagawa and coworkers, and later termed "3 rd Generation MOFs" 25-27. These materials are characterized by dynamic features of the framework structure and are also named "soft porous crystals" (SPCs). We briefly account here a few remarkable applications of the dynamic frameworks reported today as the premise for our following perspective (Fig. 1). In gas storage applications, the pore closing upon desorption provides almost ideal deliverable capacity, a key advantage compared with rigid adsorbents 28. More importantly, for gas separations, the selective response of the porous host in adapting the pore shape to a reco...

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Section: Current Understanding Of Dynamic Phenomena In Metalorganic Fmentioning

confidence: 99%

Four-dimensional metal-organic frameworks

et al. 2020

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“…For this purpose, catalyst characterization needs to be conducted operando, meaning relevant reaction conditions for a robust correlation between catalytic activity and catalyst structure. [26][27][28] In this regard, X-ray based methods like X-ray absorption spectroscopy (XAS) are attractive. Here, we use the more sophisticated photon-in/-out-technique high energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES), [29][30][31] which is especially powerful, since it employs highly penetrating X-rays and it provides indepth information on the noble metal atomic and electronic structure.…”

Section: Introductionmentioning

confidence: 99%

Unravelling the Different Reaction Pathways for Low Temperature CO Oxidation on Pt/CeO₂ and Pt/Al₂O₃ by Spatially Resolved Structure–Activity Correlations

Gänzler

Casapu

Doronkin

et al. 2019

J. Phys. Chem. Lett.

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Pt/CeO2-based catalysts are attractive for emission control applications, because of their outstanding CO oxidation performance at low temperature compared to the Al2O3-based counterpart. A detailed study of the Pt electronic structure by means of operando X-ray methods together with a spatially resolved assessment of the catalytic activity along the catalytic reactor allowed to spectroscopically identify the catalytically active Pt species at low temperature in Pt/CeO2 as reduced and CO-covered Pt nanoparticles with active metal-support interface sites. The insight was gained by spatially resolved operando X-ray absorption near edge structure (XANES) experiments in high energy resolution fluorescence detection (HERFD) mode combined with CO concentration profiles along the catalyst bed using a capillary technique. The selection of methods allowed to elucidate the interplay between catalytic activity, oxidation state and CO coverage on Pt nanoparticles in Pt/CeO2 and to unravel the special nature of Pt/CeO2 by comparison to Pt/Al2O3. At low temperature, the Pt surface is covered by CO in both catalysts according to HERFD-XANES. In contrast to Pt/Al2O3, Pt/CeO2 converts CO in the presence of CO covered Pt nanoparticles. CO concentration profiles reveal the contribution of the Pt-CeO2 interface sites to be crucial and they allow a higher CO oxidation rate of Pt/CeO2 compared to Pt/Al2O3 along the catalytic reactor at low temperature. This demonstrates the importance of correlative and advanced operando spectroscopic techniques in a spatially resolved manner. Furthermore, it consolidates the outstanding role of the noble metal-support interface in Pt/CeO2-based catalyst systems for low temperature CO oxidation.

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“…In other words, the catalyst activity is measured after the entire catalyst bed and thus integrated over all of the catalyst material in the system, irrespective of its specific local state, which may vary significantly across the bed due to temperature and reactant concentration gradients. Consequently, this combination of integral activity measurements with single point probing of catalyst material state is prone to produce erroneous structure-function relationships 9,10 . In attempts to alleviate this problem, recent studies have used a combination of techniques to both spatially and temporally investigate model 3,[11][12][13][14][15][16][17] and more complex catalysts 9,11,12,[18][19][20][21][22] , with several comprehensive reviews on the topic published recently 2,9,10,23 .…”

mentioning

confidence: 99%

Copper catalysis at operando conditions—bridging the gap between single nanoparticle probing and catalyst-bed-averaging

et al. 2020

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In catalysis, nanoparticles enable chemical transformations and their structural and chemical fingerprints control activity. To develop understanding of such fingerprints, methods studying catalysts at realistic conditions have proven instrumental. Normally, these methods either probe the catalyst bed with low spatial resolution, thereby averaging out single particle characteristics, or probe an extremely small fraction only, thereby effectively ignoring most of the catalyst. Here, we bridge the gap between these two extremes by introducing highly multiplexed single particle plasmonic nanoimaging of model catalyst beds comprising 1000 nanoparticles, which are integrated in a nanoreactor platform that enables online mass spectroscopy activity measurements. Using the example of CO oxidation over Cu, we reveal how highly local spatial variations in catalyst state dynamics are responsible for contradicting information about catalyst active phase found in the literature, and identify that both surface and bulk oxidation state of a Cu nanoparticle catalyst dynamically mediate its activity.

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Engineering operando methodology: Understanding catalysis in time and space

Cited by 40 publications

References 138 publications

Four-dimensional metal-organic frameworks

Four-dimensional metal-organic frameworks

Unravelling the Different Reaction Pathways for Low Temperature CO Oxidation on Pt/CeO₂ and Pt/Al₂O₃ by Spatially Resolved Structure–Activity Correlations

Copper catalysis at operando conditions—bridging the gap between single nanoparticle probing and catalyst-bed-averaging

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Engineering operando methodology: Understanding catalysis in time and space

Cited by 40 publications

References 138 publications

Four-dimensional metal-organic frameworks

Four-dimensional metal-organic frameworks

Unravelling the Different Reaction Pathways for Low Temperature CO Oxidation on Pt/CeO2 and Pt/Al2O3 by Spatially Resolved Structure–Activity Correlations

Copper catalysis at operando conditions—bridging the gap between single nanoparticle probing and catalyst-bed-averaging

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Unravelling the Different Reaction Pathways for Low Temperature CO Oxidation on Pt/CeO₂ and Pt/Al₂O₃ by Spatially Resolved Structure–Activity Correlations