Imide/amide hydrogen storage materials and methods
View Patent ↗In one aspect, the invention provides a hydrogen storage composition having a hydrogenated state and a dehydrogenated state. In the hydrogenated state, such composition comprises an amide and a hydride. In a dehydrogenated state, the composition comprises an imide.
1. A method of forming an imide hydrogen storage material represented by the formula, M c (NH) −2 c/2 , comprising: reacting an amide MI d (NH 2 ) d −1 with a hydride MII f H f to form the imide hydrogen storage material that reversibly stores hydrogen; where M represents at least one cationic species selected from the group consisting of Li, Mg, Na, B, Al, Be, and Zn; MI and MII represent cationic species other than hydrogen; and c, d, and f respectively represent average valence states of respectively said M, MI and MIII.
2. The method of claim 1 where the amide is lithium amide, the hydride is lithium hydride, and the imide is lithium imide.
3. The method of claim 1 wherein at least two of M, MI and MII are distinct cationic species.
4. A method of making an imide hydrogen storage material represented by M c (NH) −2 c/2 , comprising: reacting a nitride represented by the formula MIII g N 3/g with an amide represented by MI d (NH 2 ) d −1 , where M represents at least one cationic species selected from the group consisting of Li, Mg, Na, B, Al, Be, and Zn; MI and MIII represent cationic species other than hydrogen, and c, d and g represent average valence states of respectively said M, MI and MIII.
5. A method for forming a reversible imide hydrogen storage material represented by M c (NH) −2 c/2 , comprising: heating an amide compound represented by MI d (NH 2 ) d −1 for a time and at a temperature sufficient to produce reaction product comprising said reversible imide hydrogen storage material and ammonia (NH 3 ); and separating at least a portion of said ammonia from said reaction product to provide said imide material; where M represents at least one cationic species selected from the group consisting of Li, Mg, Na, B, Al, Be, and Zn; and MI represent cationic species other than hydrogen, and where c and d represent average valence states of respectively M and MI.
6. A hydrogen storage composition having an initial hydrogenated state and a subsequent dehydrogenated state:
(a) in said initial hydrogenated state, said composition comprises an amide and a hydride; and
(b) in said subsequent dehydrogenated state, said composition comprises an imide represented by M c (NH) −2 c/2 , where M represents at least one cationic species selected from the group consisting of Li, Mg, Na, B, Al, Be, and Zn, and c represents an average valence state of M, where said imide is regenerated to said initial hydrogenated state by exposure to hydrogen.
7. The composition of claim 6 wherein said imide is represented by the formula Li 2 NH.
8. The composition of claim 6 wherein said amide is represented by the formula LiNH 2 .
9. The composition of claim 6 wherein said hydride is represented by the formula LiH.
10. A method of producing a source of hydrogen gas comprising: liberating hydrogen from a hydrogenated composition comprising an amide and a hydride by heating said composition at an elevated temperature sufficient to evolve hydrogen gas therefrom so as to produce dehydrogenated product comprising an imide represented by M c (NH) −2 c/2 , where M represents at least one cationic species selected from the group consisting of Li, Mg, Na, B, Al, Be, and Zn, and c represents an average valence state of M; and then regenerating said hydrogenated composition by exposing said dehydrogenated product to hydrogen gas.
11. The method of claim 10 wherein said liberating of hydrogen is conducted at an elevated temperature greater than about 125° C.
12. The method of claim 10 wherein said liberating of hydrogen is conducted at an elevated temperature greater than about 150° C.
13. The method of claim 10 wherein said regenerating is conducted at an elevated pressure.
14. The method of claim 10 wherein said regenerating is conducted at an elevated pressure greater than about 10 kPa.
15. The method of claim 10 wherein said regenerating is conducted at an elevated pressure greater than about 200 kPa.
16. A method of cycling hydrogen comprising: mixing together at least two distinct hydrogen-containing compounds in particle form and heating said particles to release hydrogen and form an imide represented by M c (NH) −2 c/2 , where M represents at least one cationic species selected from the group consisting of Li, Mg, Na, B, Al, Be, and Zn, and c represents an average valence state of M; and then storing hydrogen by reacting hydrogen with said imide to form at least one of said two distinct hydrogen-containing compounds.
17. The method of claim 16 wherein said at least two distinct compounds comprise an amide and a hydride.
18. The method of claim 16 wherein said at least two distinct compounds comprise a first compound represented by MI d (NH 2 ) d −1 (amide) and a second compound represented by MII f H f (hydride), where MI and MII respectively represent cationic species or a mixture of cationic species other than hydrogen, and d represents an average valence state of MI and f represents an average valence state MII.
19. The method of claim 16 wherein said imide is lithium imide represented by Li 2 NH and said distinct compounds comprise a first compound represented by LiNH 2 , and a second compound represented by LiH.
20. The method of claim 16 wherein M comprises an element selected from the group consisting of Li, Mg, Na, Be, and mixtures thereof.
21. The method of claim 17 wherein said imide is represented by the formula MgNH, said amide is represented by the formula Mg(NH 2 ) 2 and said hydride is represented by the formula MgH 2 .
22. The method of claim 18 wherein at least two cationic species selected from the group consisting of said M, MI and MII are distinct cationic species.
23. The method of claim 22 wherein at least one cationic species selected from the group consisting of said MI and MII comprises said cationic species selected as M and further MI and MII optionally comprise an additional element independently selected from the group consisting of CH 3 , Al, As, B, Ba, Be, Ca, Cd, Ce, Cs, Cu, Eu, Fe, Ga, Gd, Ge, Hf, Hg, In, K, La, Li, Mg, Mn, Na, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Si, Sm, Sn, Sr, Th, Ti, TI, W, Y, Yb, Zn, Zr, and mixtures thereof.
24. The method of claim 22 wherein at least one cationic species selected from the group consisting of said MI and MII comprises said cationic species selected as M and further MI and MII optionally comprise an additional element independently selected from the group consisting of Ba, Be, Ca, Cs, Eu, In, K, La, Li, Mg, Na, Ni, Rb, Sm, Sr, Yb, and mixtures thereof.
25. The method of claim 22 wherein at least one cationic species selected from the group consisting of said MI and MII comprises said cationic species selected as M and further MI and MII optionally comprise an additional element independently selected from the group consisting of Ba, Ca, Eu, La, Li, Mg, Si, Sr, Th, Ti, Zr, and mixtures thereof.
26. The method of claim 22 wherein at least one of cationic species selected from the group consisting said MI and MII comprises said cationic species selected as M and further MI and MII optionally comprise an additional element independently selected from the group consisting of Ba, Ca, Si, Sr, Th, Ti, Zr, and mixtures thereof.
27. The method of claim 22 wherein at least one cationic species selected from the group consisting of said MI and MII comprises said cationic species selected as M and further MI and MII optionally comprise an additional element independently selected from the group consisting of Al, Ba, Be, Ca, Ce, Cs, Eu, Ga, Gd, In, K, La, Li, Mg, Mn, Na, Nd, Pb, Rb, Si, Sm, Sn, Sr, Y, Yb, Zn, and mixtures thereof.
28. The method of claim 22 wherein M, MI and MII are each elements independently selected from the group consisting of Be, Mg, Li, Na, and mixtures thereof.
29. The method of claim 16 wherein said particles are mixed together by milling.
30. A hydrogen storage system having a hydrogenated state and a dehydrogenated state:
(a) said hydrogenated state comprises a first group of particles containing an amide and a second group of particles containing a hydride; and
(b) said dehydrogenated state comprises an imide represented by M c (NH) −2 c/2 , where M represents at least one cationic species selected from the group consisting of Li, Mg, Na, B, Al, Be, and Zn, and c represents an average valence state of M, that is regenerated to said hydrogenated state by exposure to hydrogen.
31. The system of claim 30 wherein said hydrogenated state is a first condition, said dehydrogenated state is a second condition and wherein a third condition is a hydrogenated state comprising at least one of an amide and a hydride.
32. A source of hydrogen comprising a hydrogenated state comprising an amide and a hydride and a dehydrogenated state comprising an imide represented by M c (NH) −2 c/2 , where M represents at least one cationic species selected from the group consisting of: Li, Mg, Na, B, Al, Be, and Zn, and c represents an average valence state of M, where said imide is formed by reacting particles containing said amide and particles containing said hydride to release hydrogen, where said imide is regenerated to the hydrogenated state by exposure to hydrogen to form at least one of the group consisting of: said amide and said hydride.
33. The source of claim 32 where the amide is lithium amide and the hydride is lithium hydride.