The effects of sulphur poisoning on the microstructure, composition and oxygen transport properties of perovskite membranes coated with nanoscale alumina layers

Dataset underpinning the publication.<div><p>Perovskite oxides displaying mixed ionic and electronic conductivity have attracted a lot of interest for application in oxygen separation membranes. Such membranes could be used for a range of processes, including the conversion of natural gas to hydrogen or syngas. A major limitation of these materials is their tendency to segregate into simpler oxides under operating conditions, reacting with sulphur-based species often found in natural gas and leading to irreversible membrane degradation over time. Here we aim to delay or prevent this process by coating La_0.6Sr_0.4Co_0.2Fe_0.8O_3-_d membranes with <a>Alumina (Al₂O₃) </a>layers of 1 to 100 nm thickness by using atomic layer deposition. We show that coatings of about 30 nm have negligible negative effect on O₂ transport 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 thicker coatings dramatically decrease overall O₂ permeation fluxes. We also show that the irreversible sulphur poisoning under O₂ permeation conditions is linked to microstructural and composition changes at the membrane surface caused predominantly by the formation of SrSO₄ particles at the perovskite grain boundaries. </p> <div> <div><div><p><br></p> </div> </div> </div><br></div>