The effect of co-existing gases from the process of steam reforming reaction on hydrogen permeability of palladium alloy membrane at high temperatures

Hydrogen permeation measurements were carried out by using an Ag 23 wt%-Pd alloy membrane of 20 μ m thickness at temperatures from 773 to 873 K. Contrary to some reported results, hydrogen permeation flux was not affected by the co-existence of H₂ O up to 9.5% at 873 and 773 K under non-pressurized conditions. Further addition of CO₂ up to 27.9%, CH₄ up to 6.8%, CO up to 4.6% did not reduce the permeation flux. Similarly, permeation flux was not affected in a pressurized system with H₂ O up to 63%, 5% of CO with 30% of H₂ O, 20% of CH₄ with 15% of H₂ O, under 0.29 MPa pressurization at 873 K. From the hydrogen partial pressure dependence of the permeation flux, the rate determining step was concluded to be the bulk diffusion of H in the membrane under the abovementioned conditions.