Improvement of hydrogen-sorption characteristics of Mg by reactive mechanical grinding with Cr2O3Cr2O3 prepared by spray conversion

Nano-structured Cr2O3Cr2O3 powder could be produced by spray conversion (spray drying of an aqueous of Cr nitrate, oxidation and milling).The samples Mg—10 wt% Cr2O3Cr2O3 using nano-structured Cr2O3Cr2O3 synthesized by spray conversion were prepared by mechanical grinding under H2H2 (reactive mechanical grinding) under the optimum conditions, previously studied, for the preparation of the sample Mg—10 wt% Fe2O3Fe2O3 using purchased Fe2O3Fe2O3. The sample Mg—10 wt% Cr2O3Cr2O3 as milled absorbed 4.48 wt% H2H2 at 593 K under 12 bar H2H2 for 60 min. Its activation was accomplished after two hydriding–dehydriding cycles. The activated sample absorbed 5.48 wt% H2H2 for 10 min and 5.93 wt% H2H2 for 60 min at 593 K, 12 bar H2H2, and desorbed 3.65 wt% H2H2 at 603 K, 1.0 bar H2H2 for 60 min. H2H2-storage capacity was 6.38 wt% under 12 bar H2H2 at 593 K (from P–C-T curve). Reactive mechanical grinding of Mg with Cr2O3Cr2O3 by spray conversion increased the hydriding rate effectively but increased a little the dehydriding rate, compared with reactive mechanical grinding of Mg with Fe2O3Fe2O3 purchased, Fe2O3Fe2O3 by spray conversion, MnO and SiO2SiO2 by spray conversion.