DIRECT SYNTHESIS AND METHODS OF USING HYDROGEN STORAGE MATERIALS

Abstract

A method is described for the direct synthesis of reversible hydride materials by hydrogenating a mixture of aluminum, an alkali-metal hydride, and one or more of an alkali-metal amide or an alkali-metal imide, an alkaline-earth-metal or alkaline-earth-metal hydride, and a transition metal catalyst. In one embodiment, the mixture includes aluminum, LiH, LiNH2, magnesium, and TiF3 in the molar ratio of 1:1:2:1:0.05. The material is capable of being repeatedly hydrogenated and dehydrogenated. The method is likely capable of forming a variety of hydrogen storage materials that includes alanates and amides or imides, and which have high hydrogen storage capabilities without the use of ammonia. A method is also described of using two component hydrogen storage materials by segregating the material components.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a graph showing a measurement of hydrogen concentration as a function of time during the first desorption of hydrogen from a mixture;

FIG. 2 is a graph showing a measurement of hydrogen concentration as a function of time during the first absorption of hydrogen from a mixture;

FIG. 3 is a graph showing a measurement of hydrogen concentration as a function of time during the second desorption of hydrogen from a mixture;

FIG. 4 is a graph showing a measurement of hydrogen concentration as a function of time during the third desorption of hydrogen from a mixture;

FIG. 5 as a linear plot of the hydrogen pressure surrounding the material as a function of time;

FIGS. 6 and 7 are a linear plot and log plot, respectively, of the pressure of hydrogen surrounding the material as a function of the hydrogen weight percent in the mixture; and

FIG. 8 is a van't Hoff Plot from PCT isotherm measurements at 250 C, 200 C, and 180 C.

Claims

1. A method for producing compounds capable of reversible hydrogenation, comprising: forming a mixture including an alkali-metal hydride,one or more of an alkali-metal amide or an alkali-metal imide, anda material selected from the group consisting of aluminum, one or more of an alkaline-earth-metal or an alkaline-earth-metal hydride, and any combination thereof, andhydrogenating said mixture at an elevated temperature and elevated hydrogen pressure.

2. The method of claim 1, where said mixture includes a transition metal catalyst.

3. The method of claim 2, where said transition metal catalyst includes a titanium halide.

4. The method of claim 1, where said group includes one or more of an alkaline-earth-metal or an alkaline-earth-metal hydride, and where said one or more of an alkaline-earth-metal or an alkaline-earth-metal hydride includes magnesium.

5. The method of claim 1, where said alkali-metal hydride includes LiH.

6. The method of claim 5, where said group includes aluminum, and where the molar ratio of said aluminum to said LiH is approximately 1:1.

7. The method of claim 1, where said alkali-metal of said alkali-metal hydride, said alkali-metal amide or said alkali-metal imide includes one or more of lithium, sodium, or potassium.

8. The method of claim 1, where said one or more of an alkali-metal amide or an alkali-metal imide includes one or more of lithium amide, sodium amide, or potassium amide.

9. The method of claim 5, where said one or more of an alkali-metal amide or an alkali-metal imide includes LiNH2.

10. The method of claim 9, where the molar ratio of said LiNH2 to said LiH is approximately 2:1.

11. The method of claim 4, where said alkali-metal hydride includes LiH, and where the molar ratio of said Mg to said LiH is approximately 1:1.

12. The method of claim 3, where said titanium halide is TiF3, where said alkali-metal hydride includes LiH, and where the molar ratio of said TiF3 to the LiH is approximately 0.05:1.

13. The method of claim 1, where said group includes aluminum and one or more of an alkaline-earth-metal or an alkaline-earth-metal hydride.

14. The method of claim 1, wherein said step of forming is carried out in an atmosphere consisting essentially of argon.

15. The method of claim 1, wherein said elevated temperature is greater than approximately 200 C.

16. The method of claim 1, wherein said elevated pressure is approximately 125 bar.

17. The method of claim 1, where said mixing includes mixing in a ball mill.

18. A method delivering hydrogen comprising: storing an amide and a complex hydride separately in one or more interconnected vessels;decomposing said amide; andreacting gases from said decomposing amide with said complex hydride to release hydrogen.

19. The method of claim 18, where said complex hydride includes an alanate.

20. The method of claim 19, where said alanate is one or more of a lithium alanate or a sodium alanate.

21. The method of claim 18, where said amide is one or more of a lithium amide or a sodium amide.

22. The method of claim 18, where said gases include ammonia.