Tracking dynamic structural changes in catalysis by rapid 2D-XANES microscopy.

Autor: Alizadehfanaloo S; CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, DE-22607 Hamburg, Germany., Garrevoet J; Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, DE-22607 Hamburg, Germany., Seyrich M; CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, DE-22607 Hamburg, Germany., Murzin V; Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, DE-22607 Hamburg, Germany., Becher J; Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Engesserstraße 20, DE-76131 Karlsruhe, Germany., Doronkin DE; Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Engesserstraße 20, DE-76131 Karlsruhe, Germany., Sheppard TL; Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Engesserstraße 20, DE-76131 Karlsruhe, Germany., Grunwaldt JD; Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Engesserstraße 20, DE-76131 Karlsruhe, Germany., Schroer CG; CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, DE-22607 Hamburg, Germany., Schropp A; CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, DE-22607 Hamburg, Germany.
Jazyk: angličtina
Zdroj: Journal of synchrotron radiation [J Synchrotron Radiat] 2021 Sep 01; Vol. 28 (Pt 5), pp. 1518-1527. Date of Electronic Publication: 2021 Aug 12.
DOI: 10.1107/S1600577521007074
Abstrakt: Many processes and materials in heterogeneous catalysis undergo dynamic structural changes depending on their chemical environment. Monitoring such dynamic changes can be challenging using conventional spectroscopic characterization tools, due to the high time resolution required. Here, a high-resolution 2D X-ray camera operating at 50 Hz full-frame rate was synchronized with a QEXAFS monochromator, enabling rapid spectro-microscopic imaging with chemical contrast over individual pixels. This was used to monitor chemical gradients within a model Pt/Al 2 O 3 catalyst during catalytic partial oxidation of methane to synthesis gas. The transition from methane combustion (partly oxidized Pt) to combustion-reforming and partial oxidation (fully reduced Pt) was observed by a characteristic reduction front, which progressed from the end of the catalyst bed towards its beginning on the second time scale. The full-field QEXAFS imaging method applied here allows acquisition of entire XANES spectra `on the fly' in a rapid and spatially resolved manner. The combination of high spatial and temporal resolution with spectroscopic data offers new opportunities for observing dynamic processes in catalysts and other functional materials at work. The methodology is flexible and can be applied at beamlines equipped with a QEXAFS or other fast-scanning monochromators and a suitable sample environment for gas phase analytics to allow for catalytic studies at the same time.
(open access.)
Databáze: MEDLINE
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