Samples of nanoconfined Reactive Hydride Composites in resorcinol–formaldehyde (RF) aerogel scaffolds are prepared by (i) direct melt infiltration of bulk 2LiBH4–MgH2; and (ii) MgH2 impregnation and LiBH4 melt infiltration. The reaction mechanisms, kinetics and thermodynamics of the systems are determined. Activation energy (EA) and LiBH4 and MgH2 dehydrogenation enthalpies (Hdes, MgH2+ Hdes, LiBH4) of the nanoconfined 2LiBH4–MgH2 are in this work of interest. The hydrogen sorption reactions in both nanoconfined samples are reversible as shown by the recovering of LiBH4 and MgH2 after rehydrogenation. The titration results show the remarkable improvement in desorption kinetics of both nanoconfined samples over the bulk material, such as more than 90 % of overall hydrogen storage capacity is obtained within 2 h for the nanoconfined samples during the 1st dehydrogenation, while that of bulk material needs more than 16 h. The activation energy of the composites decreases by 84–150 kJ/mol (EA) due to nanoconfinement. For thermodynamics, the dehydrogenation enthalpies of LiBH4 and MgH2 (Hdes, MgH2+ Hdes, LiBH4) obtained from the nanoconfined sample reduces up to 10.61 kJ/mol H2 with respect to the bulk material.
Nanoconfined 2LiBH4-MgH2 for Reversible Hydrogen Storages: Reaction Mechanisms, Kinetics and Thermodynamics
MILANESE, CHIARA;MARINI, AMEDEO;
2013-01-01
Abstract
Samples of nanoconfined Reactive Hydride Composites in resorcinol–formaldehyde (RF) aerogel scaffolds are prepared by (i) direct melt infiltration of bulk 2LiBH4–MgH2; and (ii) MgH2 impregnation and LiBH4 melt infiltration. The reaction mechanisms, kinetics and thermodynamics of the systems are determined. Activation energy (EA) and LiBH4 and MgH2 dehydrogenation enthalpies (Hdes, MgH2+ Hdes, LiBH4) of the nanoconfined 2LiBH4–MgH2 are in this work of interest. The hydrogen sorption reactions in both nanoconfined samples are reversible as shown by the recovering of LiBH4 and MgH2 after rehydrogenation. The titration results show the remarkable improvement in desorption kinetics of both nanoconfined samples over the bulk material, such as more than 90 % of overall hydrogen storage capacity is obtained within 2 h for the nanoconfined samples during the 1st dehydrogenation, while that of bulk material needs more than 16 h. The activation energy of the composites decreases by 84–150 kJ/mol (EA) due to nanoconfinement. For thermodynamics, the dehydrogenation enthalpies of LiBH4 and MgH2 (Hdes, MgH2+ Hdes, LiBH4) obtained from the nanoconfined sample reduces up to 10.61 kJ/mol H2 with respect to the bulk material.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
