In situ X-ray diffraction computed tomography studies examining the thermal and chemical stabilities of working Ba0.5Sr0.5Co0.8Fe0.2O3- δ membranes during oxidative coupling of methane

Dorota Matras; Antonis Vamvakeros; Simon D M Jacques; Vesna Middelkoop; Gavin Vaughan; Miren Agote Aran; Robert J Cernik; Andrew M Beale

doi:10.1039/d0cp02144j

In situ X-ray diffraction computed tomography studies examining the thermal and chemical stabilities of working Ba_0.5Sr_0.5Co_0.8Fe_0.2O_{3- δ} membranes during oxidative coupling of methane

Phys Chem Chem Phys. 2020 Sep 8;22(34):18964-18975. doi: 10.1039/d0cp02144j.

Authors

Dorota Matras¹, Antonis Vamvakeros², Simon D M Jacques³, Vesna Middelkoop⁴, Gavin Vaughan⁵, Miren Agote Aran⁶, Robert J Cernik⁷, Andrew M Beale²

Affiliations

¹ School of Materials, University of Manchester, Manchester, Lancashire M13 9PL, UK. matras.dorota@gmail.com and Research Complex at Harwell, Harwell Science and Innovation Campus, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0FA, UK.
² Research Complex at Harwell, Harwell Science and Innovation Campus, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0FA, UK and Finden Limited, Merchant House, 5 East St Helen Street, Abingdon, OX14 5EG, UK. simon@finden.ac.uk and Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK. andrew.beale@ucl.ac.uk.
³ Finden Limited, Merchant House, 5 East St Helen Street, Abingdon, OX14 5EG, UK. simon@finden.ac.uk.
⁴ Sustainable Materials Management, Flemish Institute for Technological Research, VITO NV, Boeretang 200, Mol, Belgium.
⁵ ESRF - The European Synchrotron, Grenoble, 38000, France.
⁶ Research Complex at Harwell, Harwell Science and Innovation Campus, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0FA, UK and Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK. andrew.beale@ucl.ac.uk.
⁷ School of Materials, University of Manchester, Manchester, Lancashire M13 9PL, UK. matras.dorota@gmail.com.

PMID: 32597462
DOI: 10.1039/d0cp02144j

Abstract

In this study we present the results from two in situ X-ray diffraction computed tomography experiments of catalytic membrane reactors (CMRs) using Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) hollow fibre membranes and Na-Mn-W/SiO2 catalyst during the oxidative coupling of methane (OCM) reaction. The negative impact of CO2, when added to the inlet gas stream, is seen to be mainly related to the C2+ yield, while no evidence of carbonate phase(s) formation is found during the OCM experiments. The main degradation mechanism of the CMR is suggested to be primarily associated with the solid-state evolution of the BSCF phase rather than the presence of CO2. Specifically, in situ XRD-CT and post-mortem SEM/EDX measurements revealed a collapse of the cubic BSCF phase and subsequent formation of secondary phases, which include needle-like structures and hexagonal Ba6Co4O12 and formation of a BaWO4 layer, the latter being a result of chemical interaction between the membrane and catalyst materials at high temperatures.