EFFECTS OF HIGH-CONCENTRATION CO AND CO2 ON HYDROGEN PERMEATION THROUGH THE PALLADIUM MEMBRANE

The effects of high concentration CO and CO2 on the hydrogen permeation characteristics of the palladium membrane have been investigated using pure H2, H2-10%CO, H2-50%CO and H2-50%CO2 in the temperature range of 423 to 723 K and the pressure range of 0.9 to 250 kPa. The feed and bleed gases were analyzed using a quadrupole mass spectrometer. The surfaces of the samples were analyzed by means of Auger electron spectroscopy. The deterioration of the hydrogen permeability and diffusivity in the palladium membrane was observed in the case of using H2-CO(10%,50%)gases below 523 K and showed a concentration dependence of CO, while only a slight deterioration was observed in the case of using a H2-50%CO2 gas below 473 K. The results can be explained in terms of the difference in the adsorption energy of CO and CO2 at the palladium surface. The deterioration in hydrogen permeability by the contaminant gases can be attributed to the decrease in effective area for H2 dissociation by the weak adsorption of CO. © 1990, The Japan Institute of Metals. All rights reserved.