(Invited) The Role of Solid-Gas Electrochemical Interfaces for Mixed Ionic Electronic Conducting Oxygen Transport Membranes

Oxygen transport membranes are of great interest for different applications requiring oxygen due to their high efficiency and infinite selectivity. Potential membrane materials are mixed ionic-electronic conducting (MIEC) ceramics enabling oxygen transport by ion diffusion without creating a voltage due to the electrical conductivity. High performance membranes are developed consisting of thin layers on a porous support. Oxygen transport through such asymmetric membranes can be considered as a series of different processes, each of which can be rate limiting depending on operation conditions. One major resistance is concentration polarization in the support pores, which can be eliminated experimentally by using pure oxygen on the support side of the membrane. By doing so the role of oxygen surface exchange in thin perovskite layers is investigated. Different modelling approaches are described. Finally dual phase MIEC membranes, in which oxygen ions and electrons are conducted through separate phases, are briefly discussed.