X-ray physico-chemical imaging during activation of cobalt-based Fischer-Tropsch synthesis catalysts

The imaging of catalysts and other functional materials under reaction conditions has advanced significantly in recent years. The combination of the computed tomography (CT) approach with methods such as X-ray diffraction (XRD), X-ray fluorescence (XRF) and X-ray absorption near-edge spectroscopy (X...

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Bibliographic Details
Published in:Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences physical, and engineering sciences, 2018-01, Vol.376 (2110), p.20170057-20170057
Main Authors: Beale, Andrew M., Jacques, Simon D. M., Di Michiel, Marco, Mosselmans, J. Frederick W., Price, Stephen W. T., Senecal, Pierre, Vamvakeros, Antonios, Paterson, James
Format: Article
Language:English
Subjects:
Catalysis
Catalysts
Chemical synthesis
Cobalt
Computed tomography
Energy transmission
Fischer-Tropsch
Fischer-Tropsch process
Medical imaging
Physico-Chemical
Physics
Scattering
Spatial resolution
Spectroscopy
Titanium oxides
Tomography
X-ray diffraction
X-ray fluorescence
X-rays
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Summary:The imaging of catalysts and other functional materials under reaction conditions has advanced significantly in recent years. The combination of the computed tomography (CT) approach with methods such as X-ray diffraction (XRD), X-ray fluorescence (XRF) and X-ray absorption near-edge spectroscopy (XANES) now enables local chemical and physical state information to be extracted from within the interiors of intact materials which are, by accident or design, inhomogeneous. In this work, we follow the phase evolution during the initial reduction step(s) to form Co metal, for Co-containing particles employed as Fischer-Tropsch synthesis (FTS) catalysts; firstly, working at small length scales (approx. micrometre spatial resolution), a combination of sample size and density allows for transmission of comparatively low energy signals enabling the recording of 'multimodal' tomography, i.e. simultaneous XRF-CT, XANES-CT and XRD-CT. Subsequently, we show high-energy XRD-CT can be employed to reveal extent of reduction and uniformity of crystallite size on millimetre-sized TiO2 trilobes. In both studies, the CoO phase is seen to persist or else evolve under particular operating conditions and we speculate as to why this is observed. This article is part of a discussion meeting issue ‘Providing sustainable catalytic solutions for a rapidly changing world’.
ISSN:1364-503X
1471-2962
DOI:10.1098/rsta.2017.0057