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 (alpha-Al2O3) with pore size of 100 nm by adding additional layers with different proportions of YSZ/gamma-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 N-2, He and CO2 through the supported nanoporous layers have been studied in detail with permeation measurements at a temperature range of 50-400 degrees C and pressure difference of 30-100 kPa. It was observed that as the amount of gamma-Al2O3 in the nanoporous layers increases, the adsorption of CO2 is favored at low temperatures and pressures. Finally, a pore-filled Pd/YSZ/gamma-Al2O3 (60 wt%YSZ-40 wt. gamma-Al2O3) membrane was successfully prepared and its permeation performance was tested over 900 h at 500 and 550 C, showing relatively low ideal H-2/N-2 perm-selectivity of about 50 due to low hydrogen flux. (C) 2015 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.