Study on Hydrogen in Mixed Gas Separated by Rare Earth Hydrogen Storage Alloys

AB5-type rare-earth nickel (RE-Ni) based hydrogen storage alloys and AB3-type La-Mg-Ni based hydrogen storage alloys were prepared by vacuum medium-frequency induction melting in argon atmosphere. Industrial offgas was simulated by the mixed gas including H2, N2 and CH4. The purity of hydrogen separated by rare-earth hydrogen storage alloys and anti-poison and anti-pulverization properties of the alloys in the process of hydrogen absorption and desorption were studied. The results show that AB5-type RE-Ni based hydrogen storage alloys are possessed of the single structure with CaCu5-type, and AB3-type La-Mg-Ni based hydrogen storage alloys are possessed of the multi-phase structure with (La,Mg)Ni3, LaNi5 and LaNi2 phase. The hydrogen storage alloys will be poisoned by impurity gas in the separation of hydrogen, resulting in lower speed rate of hydrogen absorption and lesser capacity of hydrogen absorption. The anti-pulverization property of La-Mg-Ni based alloys is better than that of LaNi5 alloy and its complex alloy. LaNi3.7Mn0.4Al0.3Fe0.4Co0.2 alloy is considered as better alloy to separate hydrogen from the mixed gas, considering the purity of separated hydrogen, anti-poison and anti-pulverization property of the alloy. The hydrogen purity of 90.7% can be achieved.