Permeation characteristics of hydrogen through palladium membranes in binary and ternary gas mixtures

The permeances of two palladium (Pd) membranes in pure H₂, binary and ternary gas mixtures are investigated experimentally. With 10% of gas impurities (N₂, CO₂, or CO) in H₂, the profiles of dimensionless permeance suggest that H₂ permeation rate is lessened by approximately 50% to 90%, and the permeance reduced by the gas impurities is ranked as CO > CO₂ > N₂. By introducing a parameter of permeance resistance, which is the reciprocal of permeance, the permeance resistance in a ternary gas mixture can be predicted from the summation of individual permeance resistances in binary gas mixtures, revealing no synergistic effect exhibited from the interaction of contaminants. At least 75% and up to 100% of H₂ in the gas mixtures can be recovered in the membrane system, and the maximum H₂ recovery develops at the H₂ partial pressure difference of 2 or 3 atm. In the Arrhenius-type equation describing the relationship between the permeance and temperature, the activation energy is between approximately 2 and 18 kJ mole⁻¹. In general, the permeances of the membranes in gas mixtures, especially in ternary gas mixtures, are more sensitive to temperature when compared with those in pure H₂, stemming from lower activation energy exhibited.