INFLUENCES OF CO ON HYDROGENATION FOR AMORPHOUS LANI5 FILMS AND ON HYDROGEN SEPARATION USING THESE FILMS

The resistance of amorphous LaNi5 films to harmful CO in H2-CO gas mixtures was studied and H2-CO gas separation was performed using LaNi5 films deposited on a nickel-coated polymer membrane. The hydrogen absorption capacity of the LaNi5 films decreased by about 30% after exposure to H2-CO gas. The degree of decrease for the films, however, was much smaller than that reported for crystalline bulk LaNi5. As a result of the separation experiments, hydrogen in the applied gas with a composition of 50mol.%H2-50mol.%CO was concentrated to more than 98 mol.% in the permeated gas. The permeation rate for Ni/LaNi5 films was greater than that for nickel films up to about 373 K; however, the opposite tendency was observed at higher temperatures. The activation energy of hydrogen permeation estimated for the Ni/LaNi5 film was about 30 kJ(mol H2)-1 above about 343 K and 15 kJ (mol H2)-1 below this temperature. © 1990.