Experimental and theoretical investigation on hydrogen permeation with flat sheet Pd/Ag membrane for hydrogen mixture with various inlet H₂ mole fractions and species

The estimation of hydrogen permeation mole flux was performed by previously introduced theoretical equation which considers the decrease in H₂ concentration at the membrane surface, and was compared with experimental result, for various hydrogen mixtures with different inlet H₂ mole fractions and species. A flat sheet 77 wt.% Pd/23 wt.% Ag purification membrane with effective surface area of 3.14 × 10^-4 m² was used. For H₂:N₂ mixture, the comparison was performed under various feed flow rates (2.78 × 10^-5-2.50 × 10^-4 mol/s), for inlet H₂ mole fraction of 0.70-0.80, at reference membrane temperature of 623 K and total upstream pressure of 0.25 MPa. Then, nitrogen was subsequently replaced with argon (Ar), helium (He) and carbon dioxide (CO₂) to investigate the applicability of the estimation method for various H₂ mixtures with different species. The results demonstrate that the effect of H₂ permeation itself plays a significant role for permeation with H₂ mixture, which induces the phenomenon of concentration polarization. Overall, the introduced method is able to estimate H₂ permeation mole flux for H₂ mixture, both qualitatively and quantitatively, regardless of inlet H₂ mole fraction and species.