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.