Enhancement of hydrogen absorption rate of Zr₂Fe particles by NaOH pretreatment

A comparative investigation was carried out to determine which manner of pretreatment with NaOH solutions, electroless Pd-plating and Cu-plating enhances the hydrogen absorption rate of Zr₂Fe particles most greatly. The hydrogen effluent concentration from a bed packed with Zr₂Fe particles pretreated with any of the above manners was compared with that from an as-received particle bed. Numerical calculations of two equations on the hydrogen material balance and the hydrogenation rate were fitted to the experimental effluent data, and the results were correlated in terms of the hydrogen absorption capacity and the mass-transfer coefficient. The preferred manner for enhancing the hydrogenation rate was found to be treatment with a 6 N NaOH solution. The packed bed of Zr₂Fe particles pretreated with the NaOH solution can remove H₂ in a H₂-N₂-Ar stream at room temperature down to a concentration < 1 ppm. The alkali pretreatment preferentially enhances the mass-transfer rate of the solid-phase side. The effect remained unchanged within at least eight hydrogenating-dehydrogenating cycles. The Pd-plating and Cu-plating were found to be ineffective for enhancing the hydrogen absorption rate of the Zr₂Fe particles.