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.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 La0.6Sr0.4Co0.2Fe0.8O3-d membranes with Alumina (Al2O3) 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.

支撑出版物发布的该数据集涵盖了展现出混合离子与电子导电性的钙钛矿氧化物，此类材料在氧气分离膜的应用领域引起了广泛关注。此类膜可用于多种工艺，包括将天然气转化为氢气或合成气的转化过程。这些材料的主要局限性在于它们在操作条件下倾向于分解为更简单的氧化物，与天然气中常见的基于硫的物种发生反应，随着时间的推移导致膜不可逆的退化。本研究旨在通过使用原子层沉积技术，在La0.6Sr0.4Co0.2Fe0.8O3-d氧化物膜上涂覆厚度为1至100纳米的氧化铝（Al2O3）层，以延缓或防止这一过程。研究表明，约30纳米的涂层对膜跨膜氧传输通量几乎没有负面影响，并且在去除气流中的硫化氢后显示出良好的通量恢复能力。小于此临界值的涂层对不可逆中毒的保护作用甚微，而较厚的涂层则显著降低了整体的氧渗透通量。此外，我们还发现，在氧渗透条件下发生的不可逆硫中毒与膜表面由于钙钛矿晶界处SrSO4粒子的形成而引起的微结构和成分变化密切相关。