Transport of H2, O2 and H2O through single-phase, two-phase and multi-phase mixed proton, oxygen ion, and electron hole conductors

This manuscript examines the transport of H2O, H2 and O2 through membranes, which conduct protons (H+), oxygen ions (O−2) and holes (h⋅). Transport equations are derived under the assumption of steady state and fast surface kinetics. The specific cases considered here include the transport of H2O and O2 through membranes in H2O–O2 gaseous mixtures, and the transport of H2O and H2 in H2O–H2 gaseous mixtures. The transport equations show that Onsager cross coefficients are symmetric, as required. Permeation of H2O, H2, and O2 through single phase, two-phase and multiphase composite membranes is discussed. The analysis shows that the transport of neutral species, namely H2, O2, and H2O, can occur up their chemical potential gradients through the existence of cross terms.