N₂, He and CO₂ diffusion mechanism through nanoporous YSZ/γ-Al₂O₃ layers and their use in a pore-filled membrane for hydrogen membrane reactors

Nanoporous ceramic supports for pore filled membranes were prepared on ceramic supports (α-Al₂O₃) with pore size of 100 nm by adding additional layers with different proportions of YSZ/γ-Al₂O₃ (ranging from 50% to 90% of YSZ) by dip-coating and the effect of different parameters in the preparation method have been investigated. The diffusion mechanisms of N₂, He and CO₂ through the supported nanoporous layers have been studied in detail with permeation measurements at a temperature range of 50-400°C and pressure difference of 30-100 kPa. It was observed that as the amount of γ-Al₂O₃ in the nanoporous layers increases, the adsorption of CO₂ is favored at low temperatures and pressures. Finally, a pore-filled Pd/YSZ/γ-Al₂O₃ (60 wt%YSZ-40 wt. γ-Al₂O₃) membrane was successfully prepared and its permeation performance was tested over 900 h at 500 and 550 C, showing relatively low ideal H₂/N₂ perm-selectivity of about 50 due to low hydrogen flux.