International Journal of Hydrogen Energy, Vol.31, No.15, 2284-2291, 2006
Improvement of hydrogen-sorption characteristics of Mg by reactive mechanical grinding with Cr2O3 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-10wt% Cr2O3 using nano-structured Cr2O3 synthesized by spray conversion were prepared by mechanical grinding under H-2 (reactive mechanical grinding) under the optimum conditions, previously studied, for the preparation of the sample Mg-10wt% Fe2O3 using purchased Fe2O3. The sample Mg-10wt% Cr2O3 as milled absorbed 4.48wt% H-2 at 593K under 12bar H-2 for 60min. Its activation was accomplished after two hydriding-dehydriding cycles. The activated sample absorbed 5.48 wt% H-2 for 10 min and 5.93 wt% H-2 for 60 min at 593 K, 12 bar H-2, and desorbed 3.65 wt% H-2 at 603 K, 1.0 bar H-2 for 60 min. H-2-storage capacity was 6.38 wt% under 12 bar H-2 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. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
Keywords:H-2-sorption characteristics of Mg;Cr2O3 addition;spray conversion;reactive mechanical grinding;hydriding and dehydriding rates