Preparation of aluminum hydride polymorphs, particularly stabilized .alpha.-alh3

• US 6,228,338 B1
• Filed: 06/16/1999
• Issued: 05/08/2001
• Est. Priority Date: 06/16/1999
• Status: Expired due to Term

• Current Assignee: Ardica Technologies Incorporated
• Original Assignee: SRI International, Inc.
• Inventors: Bottaro, Jeffrey C., Schmitt, Robert J., Penwell, Paul E., Bomberger, David C., Petrie, Mark A.
• Primary Examiner(s): LANGEL, WAYNE A
• Application Number:
  US09/334,359
• Time in Patent Office: 692 Days
• Field of Search: 423/645, 423/265, 423/274
• US Class Current: 423/265
• CPC Class Codes: C01B 6/06 Hydrides of aluminium, gallium, indium, thallium, germanium, tin, lead, arsenic, antimony, bismuth or polonium; Monoborane; Diborane; Addition complexes thereof
• CPC Class Codes: C06B 45/10 the organic component containing a resin
• CPC Class Codes: H01M 4/242 Hydrogen storage electrodes
• CPC Class Codes: H01M 8/065 by dissolution of metals or alloys; by dehydriding metallic substances
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

The present invention features methods for preparing stabilized α-AlH₃ and α′-AlH₃, compositions containing these alane polymorphs, e.g., energetic compositions such as rocket propellants, and methods for using the novel polymorphs as chemical reducing agents, polymerization catalysts, and as a hydrogen source in fuel cells and batteries. The method produces stabilized alane by treating α-AlH₃ with an acidic solution that optionally contains a stabilizing agent such as an electron donor, an electron acceptor, or a compound which coordinates the Al³⁺ ion.

Claims

1. A method for preparing α

-AlH₃, comprising the steps of;

(a) reacting an alkali metal hydride with AlCl₃ in a solution of diethyl ether to form an initial AlH₃ product in a reaction mixture, along with an alkali metal chloride;

(b) removing the alkali metal chloride from the reaction mixture by filtration;

(c) adding an excess of toluene to the filtrate resulting from step (b), providing a diethyl ether-toluene solution;

(d) heating and distilling the diethyl ether-toluene solution to reduce the amount of diethyl ether in the solution, until a precipitate is formed;

(e) isolating the precipitate; and

(f) adding the precipitate to an acidic solution effective to dissolve and thus remove materials other than α

-AlH₃.

2. The method of claim 1, further comprising:

(g) isolating α

-AlH₃ from the acidic solution.

3. The method of claim 1, wherein the acidic solution of step (f) contains an α

-AlH₃ stabilizing agent.

4. The method of claim 3, wherein the α

-AlH₃ stabilizing agent comprise a compound that coordinates to the Al³⁺ ion.

5. The method of claim 4, wherein the α

-AlH₃ stabilizing agent is aluminon.

6. The method of claim 4, wherein the α

-AlH₃ stabilizing agent is 8-hydroxyquinoline.

7. The method of claim 4, wherein the α

-AlH₃ stabilizing agent is catechol.

8. The method of claim 3, wherein the α

-AlH₃ stabilizing agent is an electron donor or an electron acceptor.

9. The method of claim 8, wherein the electron donor or electron acceptor is selected from the group consisting of tetrachlorobenzoquinone, diphenylamine, tetracyanoethylene, 7,7,8,8-tetracyanoquinodimethane, tetrathiafulvalene and tetrakis(dimethylamino)ethylene.

10. The method of claim 1, further including, after step (b) and prior to step (d), adding an additional alkali metal hydride to the reaction mixture and/or the diethyl ether-toluene solution, followed by a further filtration step, wherein the additional alkali metal hydride may or may not be the same as the alkali metal hydride of step (a).

11. The method of claim 1, wherein the alkali metal hydride is LiAlH₄.

12. The method of claim 1, wherein the alkali metal hydride is LiBH₄.

13. The method of claim 1, wherein the molar ratio of the alkali metal hydride to AlCl₃ in step (a) is in the range of approximately 3:

1 to 4.5;

1.

14. The method of claim 1, wherein the acidic solution is an HCl solution.

15. The method of claim 14, wherein the acidic solution is approximately 5% to 15% (w/w) HCl.