Hydrogen permeability of SrCe 1− xM xO 3− δ ( x=0.05, M=Eu, Sm)

Abstract

The hydrogen permeability of SrCe 0.95Eu 0.05O 3− δ and SrCe 0.95Sm 0.05O 3− δ was studied as a function of temperature, hydrogen partial pressure ( P H 2 ) gradient, and water vapor partial pressure ( P H 2O ) gradient. Under a 100% dry hydrogen condition at 1123 K, the hydrogen permeation rates of dense membranes (1.72 mm thick) are ≈3.19×10 −9 mol/cm 2 s for SrCe 0.95Eu 0.05O 3− δ and 2.33×10 −9 mol/cm 2 s for SrCe 0.95Sm 0.05O 3− δ . Under wet hydrogen conditions at 1123 K, the hydrogen permeation rates are ≈2.89×10 −9 and 1.21×10 −9 mol/cm 2 s, respectively, for the same materials. The dopant dependence of hydrogen permeability is explained in terms of the ionization potential of the dopant. Electronic conductivity was calculated from hydrogen permeation fluxes; activation energies for electron conduction under both dry and wet conditions were also calculated. The P H 2O dependence of electronic conductivity and hydrogen permeability is discussed.