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.