Recovery of low-concentration hydrogen from different gas streams with Zr₂Fe particle beds

A Zr₂Fe particle bed under a once-through operation was investigated for continuous recovery of low-concentration hydrogen from argon, nitrogen and oxygen streams. The particle bed after activation at 800 °C under vacuum effectively removed hydrogen from the nitrogen and argon streams above 150 °C to a level lower than the detection limit of a gas chromatograph. However, it failed to recover hydrogen from atmospheres including 650 ppm oxygen due to generation of water vapor and decrease in the hydrogen absorption capacity. The effluent curve in the low hydrogen concentration region was controlled by the hydrogenation reaction on particle surfaces; that in the saturation region was controlled by the solid-film mass-transfer process. The activation energy of the latter was 5.46 kJ mol^-1.