PROCESSES FOR SYNTHESIZING ALKALI METAL BOROHYDRIDE COMPOUNDS

• US 20030114632A1
• Filed: 12/18/2001
• Published: 06/19/2003
• Est. Priority Date: 12/18/2001
• Status: Active Grant

• Current Assignee: Millennium Cell Inc.
• Original Assignee: Millennium Cell Inc.
• Inventors: Ortega, Jeffrey V., Kelly, Michael T., Wu, Ying, Amendola, Steven C.
• Granted Patent: US 6,586,563 B1
• Time in Patent Office: Days
• US Class Current: 528/196
• CPC Class Codes: C01B 6/21 Preparation of borohydrides of alkali metals, alkaline earth metals, magnesium or beryllium; Addition complexes thereof, e.g. LiBH4.2N2H4, NaB2H7
• CPC Class Codes: C01B 6/23 Preparation of borohydrides of other metals, e.g. aluminium borohydride; Addition complexes thereof, e.g. Li[Al(BH4)3H]

Abstract

Processes for synthesizing borohydride compounds with reduced energy requirements and high efficiency are disclosed. The processes include the reaction of a base with a borane complex or diborane to produce a borohydride compound of formula YBH₄, where Y is a monovalent cationic moiety.

Claims

1. A process for producing borohydride compounds, comprising reacting diborane with a carbonate compound of formula Y₂CO₃ in aqueous solution at a temperature of about −

5 to about 20°

C., wherein Y is a monovalent cationic moiety, thereby producing a borohydride compound of formula YBH₄.

2. The process according to claim 1, further comprising submerging a dispersion tube in the aqueous solution.

3. The process according to claim 1, further comprising submerging a gas inlet tube in the aqueous solution.

4. The process according to claim 1, wherein Y is selected from the group consisting of alkali metals, pseudo-alkali metals, and a quaternary ammonium ion of formula NR₄⁺, wherein R is hydrogen, a straight chain C₁ to C₄ alkyl group, a branched chain C₁ to C₄ alkyl group, or a mixture thereof.

5. The process according to claim 4, wherein Y is selected from the group consisting of Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Fr⁺, NH₄⁺, Tl⁺, and a quaternary ammonium ion of formula NR₄⁺, wherein R is hydrogen, a straight chain C₁ to C₄ alkyl group, or a branched chain C₁ to C₄ alkyl group.

6. The process according to claim 5, wherein Y is selected from the group consisting of Na⁺, Li⁺, and K⁺.

7. The process according to claim 1, comprising providing between about one and about five molar equivalents of the carbonate compound for every molar equivalent of diborane.

8. The process according to claim 1, wherein the process is performed in batch mode.

9. The process according to claim 1, wherein the process is performed in continuous mode.

10. The process according to claim 9, comprising continuously providing diborane with a gas recycle pump.

11. The process according to claim 1, wherein the aqueous solution temperature is between about 0 and about 5°

C.

12. A process for producing borohydride compounds, wherein the process comprises reacting a borane complex with a base in a solution comprising a non-aqueous polar solvent, thereby providing a borohydride compound of formula YBH₄, wherein Y is a monovalent cationic moiety and the base is selected from the group consisting of a hydroxide of formula YOH and a carbonate of formula Y₂CO₃.

13. The process according to claim 12, wherein Y is selected from the group consisting of alkali metals, pseudo-alkali metals, and a quaternary ammonium ion of formula NR₄⁺ wherein R is a straight chain C₁ to C₄ alkyl group, a branched chain C₁ to C₄ alkyl group, or a mixture thereof.

14. The process according to claim 13, wherein Y is selected from the group consisting of Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Fr⁺, Tl⁺, and a quaternary ammonium ion of formula NR₄⁺, wherein R is a straight chain C₁ to C₄ alkyl group or a branched chain C₁ to C₄ alkyl group.

15. The process according to claim 14, wherein Y is selected from the group consisting of Na⁺, Li⁺, and K⁺.

16. The process according to claim 12, wherein the non-aqueous polar solvent is an organic glyme.

17. The process according to claim 12, wherein the borane complex and the base are reacted at a temperature between about −

5 and about 30°

C.

18. The process according to claim 12, wherein the borane complex and the base are reacted for a time period between 2 and 70 hours.

19. The process according to claim 12, wherein the borane complex is selected from the group consisting of borane-tetrahydrofuran, borane-morpholine, borane-ammonia, borane-triethylamine, borane-trimethylamine, borane-N,N-diethylaniline, borane-dimethylamine, borane-dimethylsulfide, borane-tert-butylamine, borane-diethylamine, borane-iso-propylamine and borane-pyridine.

20. The process according to claim 19, wherein the borane complex is selected from the group consisting of borane-tetrahydrofuran and borane-triethylamine.

21. A process for producing borohydride compounds, comprising reacting gaseous diborane with a base in the solid phase in the absence of solvent, thereby providing a borohydride of formula YBH₄, where Y is a monovalent cationic moiety and the base is selected from the group consisting of a hydroxide of formula YOH and a carbonate of formula Y₂CO₃.

22. The process according to claim 21, further comprising agitating the gaseous diborane and the base with milling media in a ballmill vessel, wherein the ballmill vessel is rotated by a mill.

23. The process according to claim 21, wherein Y is selected from the group consisting of alkali metals, pseudo-alkali metals, and a quaternary ammonium ion of formula NR₄⁺, wherein R is a straight chain C₁ to C₄ alkyl group, a branched chain C₁ to C₄ alkyl group, or a mixture thereof.

24. The process according to claim 23, wherein Y is selected from the group consisting of Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Fr⁺, Tl⁻

, and a quaternary ammonium ion of formula NR₄⁺, wherein R is a straight chain C₁ to C₄ alkyl group or a branched chain C₁ to C₄ alkyl group.

25. The process according to claim 24, wherein Y is selected from the group consisting of Na⁺, Li⁺, and K⁺.

26. The process according to claim 21, wherein the gaseous diborane and the base are reacted at a temperature between about −

5 and about 70°

C.

27. The process according to claim 26, wherein the temperature is between about 0 and about 30°

C.

28. The process according to claim 21, wherein the gaseous diborane and the base are reacted for a time period between 2 and 100 hours.

29. The process according to claim 21, comprising providing between about one and about ten molar equivalents of the base for every molar equivalent of diborane.

30. The process according to claim 21, wherein the gasesous diborane and the base are reacted at a pressure between about 14 psi and about 200 psi.

31. The process according to claim 30, wherein the gasesous diborane and the base are reacted at a pressure between about 14 psi and about 100 psi.

32. A process for producing borohydride compounds, comprising reacting gaseous diborane with a base suspended in a non-aqueous polar solvent, thereby providing a borohydride of formula YBH₄, where Y is a monovalent cationic moiety and the base is selected from the group consisting of a hydroxide of formula YOH and a carbonate of formula Y₂CO₃.

33. The process according to claim 32, further comprising agitating the gaseous diborane, the base, and the non-aqueous polar solvent with milling media in a ballmill vessel, wherein the ballmill vessel is rotated by a mill.

34. The process according to claim 32, wherein Y is selected from the group consisting of alkali metals, pseudo-alkali metals, and a quaternary ammonium ion of formula NR₄³⁰ , wherein R is a straight chain C₁ to C₄ alkyl group, a branched chain C₁ to C₄ alkyl group, or a mixture thereof.

35. The process according to claim 34, wherein Y is selected from the group consisting of Li⁺, Na⁺, K⁺, Rb⁻

, Cs⁺, Fr⁺, Tl⁺, and a quaternary ammonium ion of formula NR₄⁺, wherein R is a straight chain C₁ to C₄ alkyl group or a branched chain C₁ to C₄ alkyl group.

36. The process according to claim 35, wherein Y is selected from the group consisting of Na⁺, Li⁻

, and K⁺.

37. The process according to claim 32, wherein the non-aqueous polar solvent is an organic glyme.

38. The process according to claim 32, wherein the gaseous diborane and the base are reacted at a temperature between about −

5 and about 70°

C.

39. The process according to claim 38, wherein the temperature is between about 0 and about 30°

C.

40. The process according to claim 32, wherein the gaseous diborane and the base are reacted for a time period between 2 and 70 hours.

41. The process according to claim 32, comprising providing between about one and about ten molar equivalents of the base for every molar equivalent of diborane.

42. The process according to claim 32, wherein the gasesous diborane and the base are reacted at a pressure between about 14 psi and about 200 psi.

43. The process according to claim 42, wherein the gasesous diborane and the base are reacted at a pressure between about 14 psi and about 100 psi.

44. A process for producing borohydride compounds, comprising:

(a) reacting gaseous diborane with a carbonate of formula Y₂CO₃ in the solid phase in the absence of solvent, thereby providing a borohydride of formula YBH₄, a borate of formula YBO₂, and unreacted solid carbonate, where Y is a monovalent cationic moiety;

(b) isolating the borohydride;

(c) adding an alcohol, wherein the borate is substantially soluble in the alcohol and the unreacted solid carbonate is substantially insoluble in the alcohol; and

(d) isolating the unreacted solid carbonate.

45. A process for producing borohydride compounds, comprising:

(a) reacting gaseous diborane with a carbonate of formula Y₂CO₃ suspended in a nonaqueous polar solvent, thereby providing a borohydride of formula YBH₄, a borate of formula YBO₂, and unreacted solid carbonate, where Y is a monovalent cationic moiety;

(b) isolating the borohydride;

(c) adding an alcohol, wherein the borate is substantially soluble in the alcohol and the unreacted solid carbonate is substantially insoluble in the alcohol; and

(d) isolating the unreacted solid carbonate.