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Operando and Postreaction Diffraction Imaging of the La-Sr/CaO Catalyst in the Oxidative Coupling of Methane Reaction

Matras, D; Jacques, SDM; Poulston, S; Grosjean, N; Estruch Bosch, C; Rollins, B; Wright, J; ... Beale, AM; + view all (2019) Operando and Postreaction Diffraction Imaging of the La-Sr/CaO Catalyst in the Oxidative Coupling of Methane Reaction. Journal of Physical Chemistry C , 123 (3) pp. 1751-1760. 10.1021/acs.jpcc.8b09018. Green open access

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Abstract

A La−Sr/CaO catalyst was studied operando during the oxidative coupling of methane (OCM) reaction using the X-ray diffraction computed tomography technique. Full-pattern Rietveld analysis was performed in order to track the evolving solid-state chemistry during the temperature ramp, OCM reaction, as well as after cooling to room temperature. We observed a uniform distribution of the catalyst main components: La2O3, CaO−SrO mixed oxide, and the hightemperature rhombohedral polymorph of SrCO3. These were stable initially in the reaction; however, doubling the gas hourly space velocity resulted in the decomposition of SrCO3 to SrO, which subsequently led to the formation of a second CaO−SrO mixed oxide. These two mixed CaO−SrO oxides differed in terms of the extent of Sr incorporation into their unit cell. By applying Vegard’s law during the Rietveld refinement, it was possible to create maps showing the spatial variation of Sr occupancy in the mixed CaO−SrO oxides. The formation of the Srdoped CaO species is expected to have an important role in this system through the enhancement of the lattice oxygen diffusion as well as increased catalyst basicity.

Type: Article
Title: Operando and Postreaction Diffraction Imaging of the La-Sr/CaO Catalyst in the Oxidative Coupling of Methane Reaction
Open access status: An open access version is available from UCL Discovery
DOI: 10.1021/acs.jpcc.8b09018
Publisher version: https://doi.org/10.1021/acs.jpcc.8b09018
Language: English
Additional information: This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. http://creativecommons.org/licenses/by/4.0/
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10068345
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