The effects of high concentrations of CO and CO2 upon the H permeation behavior of a Pd membrane were investigated by using pure H2, H2-10%CO, H2-50%CO and H2-50%CO2 at temperatures ranging from 423 to 723K and pressures ranging from 0.9 to 250kPa. A deterioration of the H permeability and diffusivity was observed in the presence of H2 with 10 or 50% of CO, at temperatures below 523K (figures 29 and 30). Only a slight deterioration was observed when using H2-50%CO2 gas at temperatures below 473K. The results were explained in terms of the difference in the adsorption energies of CO and CO2 at the Pd surface. The deterioration in H permeability, due to the presence of the gases, was attributed to a decrease in the effective area for H2 dissociation via the weak adsorption of CO.

Effects of High Concentration CO and CO2 on Hydrogen Permeation through the Palladium Membrane. M.Amano, C.Nishimura, M.Komaki: Materials Transactions, 1990, 31[5], 404-8