Characterising Transport Routes in Dual-phase Molten-salt Membranes for Carbon Dioxide Separation

支撑熔盐膜（MSM）是一种类型的双相气体分离膜，其由固体无机支撑物（通常为陶瓷，氧化铝），其已经用熔融盐例如碱金属碳酸盐浸渍。熔融盐（MS）通过毛细管力保留在载体的孔隙空间内。在过去的几十年中，工作已经证明这些膜的显着高的选择性和渗透性，这是数量级超过那些普通的聚合物膜，归因于促进运输机制在MSM的气体转移。在该过程中，气体在膜的进料侧与离子发生化学反应，形成新的离子物质，碳酸根离子通过膜扩散到渗透侧。在那里，气体从膜中释放出来，离子通过进料侧反应的逆反应再生。这类膜的发展导致了许多潜在的优势，在一个较小的足迹相比，目前的CCS技术，因此，这些膜提出了一个有吸引力的选择，用于分离二氧化碳从混合气体streams.Detailed调查到修改支持功能揭示运输机制和CO2通量的影响。虽然广泛的研究已经解决了载体改性的影响，但对MS与载体材料的特定相互作用及其对CO2渗透的影响的探索有限。无机载体的性质决定了CO2运输的机制。各种类型的膜载体，例如惰性载体如氧化铝、电子传导载体如银和氧化物离子传导材料如钙钛矿，都导致不同的传输机制。虽然运输方法往往是相互排斥的，但人们一直在努力将多种方法结合起来，从而提高记录的通量。本研究将透过光谱、渗透、绕射等技术，探讨固体载体、质谱及两者之间的界面，探讨其传输机制。关键的调查将集中在阐明MS的形态，了解离子传输在任何一个或两个阶段的作用，并确定新的界面物种。该项目旨在进一步揭示两相熔盐膜中CO2分离的机制。

Supported molten-salt membranes (MSMs) are a type of dual-phase gas separation membrane, consisting of a solid inorganic support (typically a ceramic e.g., alumina) which has been impregnated with a molten salt such as an alkali metal carbonate. The molten salt (MS) is retained within the pore space of the support via capillary forces. Over the past few decades work has demonstrated these membranes' notably high selectivities and permeabilities, which are orders of magnitude beyond those of common polymeric membranes, attributed to the facilitated-transport mechanism in MSMs for gas transfer. In this process, the gas undergoes chemical reactions with ions at the feed side of the membrane, forming new ionic species e.g., carbonate ions, that diffuse through the membrane to the permeate side. There, the gas is released from the membrane, and the ions are regenerated through the reverse of the feed side reaction. The development of this class of membrane leads into many potential advantages in terms of a smaller footprint compared to current CCS technologies and as such, these membranes present an appealing option for the separation of carbon dioxide from mixed gas streams.Detailed investigations into modifying support functionality reveal impacts on transport mechanisms and CO2 flux. While extensive research has addressed the influence of support modification, limited exploration exists on the MS's specific interactions with the support material and their effects on CO2 permeation. The nature of the inorganic support dictates the mechanism of CO2 transport. Various types of membrane support, such as inert ones like alumina, electron-conducting supports like silver, and oxide ion conducting materials such as perovskite, all result in different transport mechanisms. While transportation methods tend to be mutually exclusive, efforts have been directed toward combining multiple approaches, leading to higher recorded fluxes. This has promoted the development of mixed ionic electronic conducting supports, facilitating both oxide ion and electron conduction.This research will probe the transport mechanism through a range of spectroscopic, permeation, and diffraction techniques to investigate the solid support, MS, and the interface between the two. Key inquiries will focus on elucidating the speciation of the MS, understanding the role of ion transport in either or both phases, and identifying novel interfacial species. The project aims to reveal further insights into the mechanisms governing CO2 separation in dual-phase molten-salt membranes.