Water splitting for hydrogen generation over lanthanum-calcium-iron perovskite-type membrane driven by reducing atmosphere

Abstract

Here, we systematically investigated the behavior of water splitting in a La0.9Ca0.1FeO3−δ (LCF-91) perovskite-type oxygen-transport membrane (OTM) reactor driven by different reducing atmospheres (i.e., CO, H2/CO and CH4). The LCF-91 membrane showed favorable oxygen permeability and hydrogen production rates toward different reducing atmospheres (0.0617, 0.0523 and 0.0390 μmol s−1 cm−2 for CO, H2/CO and CH4 reducing gases, respectively). The activation of CO is easier than that of CH4 over the surface of LCF-91, which promotes the surface oxygen diffusion and following oxygen permeation rate. Further crystallization of the membrane materials is observed during the water splitting test, which is much more serious for the side exposing in the oxidation atmosphere (steam side) compared with the reducing atmospheres. Grain growth of materials in both reduction and oxidation sides of membrane is associated with the reducing atmospheres, and the growth rate follows a rank order of CH4 > H2/CO > CO. This crystallization of LCF-9 membrane materials is beneficial for improving the stability of the reactor for successive generation of hydrogen. The LCF-91 membrane reveals a favorable stability during the CH4-driven water splitting test.