Hydrogen permeation in asymmetric La28 − xW4 + xO54 + 3x/2 membranes

Asymmetric supported La28 − xW4 + xO54 + 3x/2 (La/W ≈ 5.6) membranes were investigated for their hydrogen permeation properties as a function of temperature and feed gas conditions. Dense membranes of thickness 25–30 μm supported on substrates with 25 and 40 vol.% porosity were compared. Above 850 °C under dry conditions, the hydrogen permeation rate was approximately constant as a function of temperature due to low concentration of protons in the material at high temperatures. Under humid conditions and above 960 °C enhanced permeation rates were observed. A hydrogen permeation as high as 0.14 NmL min−1 cm−2 was recorded at 1000 °C with 10 vol.% H2 (2.5 vol.% H2O) as feed gas.

► Lanthanum tungstate is a promising hydrogen permeable membrane material. ► For membranes ∼25–30 μm permeation is limited by proton conduction at >800–850 °C. ► Hydrogen permeation is limited by n-type conductivity at <800 °C. ► Adding water vapour enhances the hydrogen permeation at high temperatures.