Specific permeabilities and diffusion constants for H have been measured in a series of Pd-Al alloy membranes using a new method for activation of the membranes. The membranes have been partially internally oxidized at an elevated temperature before inserting into the apparatus for measuring H 2 permeabilities. If the percent internal oxidation is small relative to the membrane thickness, the diffusion takes place essentially through the unoxidized alloys. The activation energy for diffusion of H increases with atom fraction Al from 23.2 kJ/mol 1/2H 2 (X Al =0) to 25.1 J/mol 1/2H 2 (X Al =0.08). It is shown that the partially oxidized alloys are more resistant to CO poisoning than unoxidized alloys. The resistance of the partially internally oxidized alloys towards poisoning by CO (g) increases and the diffusion constants decrease with X Al .

No abstract

No abstract

No abstract