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Lookup NU author(s): Dr Guangru Zhang, Dr Dragos Neagu, Dr Peter King, Professor Anthony O'Neill, Professor Ian Metcalfe
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Perovskite oxides displaying mixed ionic and electronic conductivity have attracted a lot of interest for applicationin oxygen separation membranes. Such membranes could be used for a range of processes, including theconversion of natural gas to hydrogen or syngas. A major limitation of these materials is their tendency tosegregate into simpler oxides under operating conditions, reacting with sulphur-based species often found innatural gas and leading to irreversible membrane degradation over time. Here we aim to delay or prevent thisprocess by coating La0.6Sr0.4Co0.2Fe0.8O3-δ membranes with Alumina (Al2O3) layers of 1–100 nm thickness byusing atomic layer deposition. We show that coatings of about 30 nm have negligible negative effect on O2transport flux across the membrane and display good flux recovery when H2S is removed from the stream.Coatings thinner than this critical value provide little protection against irreversible poisoning while thickercoatings dramatically decrease overall O2 permeation fluxes. We also show that the irreversible sulphurpoisoning under O2 permeation conditions is linked to microstructural and composition changes at the membranesurface caused predominantly by the formation of SrSO4 particles at the perovskite grain boundaries.
Author(s): Zhang G, Neagu D, King PJ, Ramadan S, O'Neill A, Metcalfe IS
Publication type: Article
Publication status: Published
Journal: Journal of Membrane Science
Year: 2021
Volume: 618
Print publication date: 15/01/2021
Online publication date: 11/09/2020
Acceptance date: 07/09/2020
Date deposited: 26/10/2020
ISSN (print): 0376-7388
ISSN (electronic): 1873-3123
Publisher: Elsevier
URL: https://doi.org/10.1016/j.memsci.2020.118736
DOI: 10.1016/j.memsci.2020.118736
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