Effect of Milling Parameters on the Dehydrogenation Properties of the Mg−Ti−H System

Magnesium-based alloys are promising candidates as potential hydrogen storage materials due to their inherent high hydrogen contents. Small particle size which can be achieved by milling and small amounts of transition-metal compounds as catalysts result in increased hydrogen release/uptake kinetics. In this work, we examined the effects of various milling parameters and TiH2 content on the dehydrogenation properties of the Mg−Ti−H system. The samples were prepared with different amounts of TiH2 using various milling methods and conditions. The activation energy and the enthalpy change of dehydrogenation of the milled samples were determined by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results indicated that, among a variety of MgH2/TiH2 ratios and milling conditions, samples with 9.1 mol % TiH2 milled in a dual-planetary high energy mill for 4 h under 15 MPa hydrogen pressure were found to be the optimal materials, displaying a substantially reduced activation energy and enthalpy change for MgH2 dehydrogenation.