Hydrogen storage material and process using graphite additive with metal-doped complex hydrides
View Patent ↗A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH 4 . The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.
1. A reversible hydrogen storage composition comprising:
an AlH 3 -based complex hydride;
a catalytically effective amount of a titanium dopant;
an effective amount of an aluminum additive sufficient to protect the dehydration kinetics of the complex hydride from cycle degradation; and,
an effective amount of graphite sufficient to enhance the rate of hydrogen desorption of the complex hydride;
wherein said AlH 3 -based complex hydride, said effective amount of aluminum additive, said effective amount of graphite, and said titanium dopant are co-processed through a ball-mill apparatus thereby providing a reversible hydrogen storage composition.
2. The hydrogen storage composition according to claim 1 wherein said effective amount of an aluminum additive is about 5 wt % of said hydrogen storage material.
3. The hydrogen storage composition according to claim 1 wherein the effective amount of graphite is about 10 wt % of said hydrogen storage material.
4. The hydrogen storage composition according to claim 1 wherein said catalytically effective amount of said titanium dopant is about 2 mole % titanium.
5. A reversible hydrogen storage material comprising:
the complex sodium aluminum hydride;
a titanium catalyst present in an amount of about 2 mole %;
a graphite additive present in an amount of between about 5 wt % to about 10 wt %;
an aluminum additive present in an amount of about 5 wt %;
wherein said sodium aluminum hydride, said titanium catalyst, said graphite and said aluminum additive are subjected to a ball-milling process, thereby forming a hydrogen storage material.
6. The hydrogen storage material according to claim 5 wherein said hydrogen storage material has a hydrogen desorption rate approximately six times greater than the corresponding hydrogen storage material having no graphite additive.