Enhancement of the Hydriding and Dehydriding Rates of Mg by Adding TiCl3 and Reactive Mechanical Grinding

Abstract

A sample with a composition of 95 wt% Mg-5 wt% TiCl3 (named Mg-5TiCl3) was prepared by reactive mechanical grinding, and its hydriding and dehydriding properties were examined. The activation of Mg-5TiCl3 was not required. Mg-5TiCl3 had an effective hydrogen-storage capacity of about 6.2 wt%. At the first cycle (n=1), the sample absorbed 5.77 wt% H for 5 min, 6.07 wt% H for 10 min, 6.17 wt% H for 30 min, and 6.19 wt% H for 60 min at 573 K under 12 bar H2. At n=1, the sample desorbed 0.03 wt% H for 2.5 min, 0.13 wt% H for 30 min, and 0.35 wt% H for 60 min at 573 K under 1.0 bar H2. Mg-5TiCl3 after reactive mechanical grinding contained Mg, β-MgH2, γ-MgH2, and TiH1.924. The XRD pattern of Mg-5TiCl3 dehydrided at the 4th hydriding-dehydriding cycle at 423-573 K contained β-MgH2, Mg, MgO, and TiH1.924. Mg-5TiCl3 had a higher initial hydriding rate and a larger quantity of hydrogen absorbed for 60 min than Mg-5TaF5, Mg-10Fe2O3, Mg-10MnO, and Mg, the hydrogen-storage properties of which were previously reported.(Received February 12, 2014)