The effects of sulphur poisoning on the microstructure, composition andoxygen transport properties of perovskite membranes coated withnanoscale alumina layers

Lookup NU author(s): Dr Guangru Zhang, Dr Dragos Neagu, Dr Peter King, Professor Anthony O'Neill, Professor Ian Metcalfe

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Abstract

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.

Publication metadata

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:

DOI: 10.1016/j.memsci.2020.118736

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