Improvement of hydrogen-sorption characteristics of Mg by reactive mechanical grinding with prepared by spray conversion

Nano-structured Cr₂O₃ powder could be produced by spray conversion (spray drying of an aqueous of Cr nitrate, oxidation and milling).The samples Mg—10 wt% Cr₂O₃ using nano-structured Cr₂O₃ synthesized by spray conversion were prepared by mechanical grinding under H₂ (reactive mechanical grinding) under the optimum conditions, previously studied, for the preparation of the sample Mg—10 wt% Fe₂O₃ using purchased Fe₂O₃. The sample Mg—10 wt% Cr₂O₃ as milled absorbed 4.48 wt% H₂ at 593 K under 12 bar H₂ for 60 min. Its activation was accomplished after two hydriding–dehydriding cycles. The activated sample absorbed 5.48 wt% H₂ for 10 min and 5.93 wt% H₂ for 60 min at 593 K, 12 bar H₂, and desorbed 3.65 wt% H₂ at 603 K, 1.0 bar H₂ for 60 min. H₂-storage capacity was 6.38 wt% under 12 bar H₂ at 593 K (from P–C-T curve). Reactive mechanical grinding of Mg with Cr₂O₃ by spray conversion increased the hydriding rate effectively but increased a little the dehydriding rate, compared with reactive mechanical grinding of Mg with Fe₂O₃ purchased, Fe₂O₃ by spray conversion, MnO and SiO₂ by spray conversion.