Magnesium hydride, a compound potentially applicable as a hydrogen carrier and energy storage material, releases hydrogen via hydrolysis or thermolysis.Ball-milled MgH2 composites were studied to optimize the kinetics and yield of the dehydriding process. Milling MgH2, under inert atmosphere increased the susceptibility to oxidation: the amount of MgO produced following air exposure of pulverized MgH2 was found to be proportional to the milling duration.Incorporation of protective coatings to avoid undesirable oxidation was studied: addition of anionic surfactants or expanded graphite as milling aids reduces the susceptibility of MgH2 to oxidation, presumably via formation of a protective layer. Such coatings minimize the access of oxygen to the particle surface upon exposure to air and facilitate manipulations, such as performing analysis, under ambient atmosphere.Improved dehydriding efficiency of oxidation-protected milled composites was demonstrated.Hydrolysis of pristine magnesium hydride and MgH2-composites with aqueous hydrolysates containing aprotic polar solvents demonstrated a significant increase of dehydriding efficiency.
Read full abstract