Solid compositions generating hydrogen by combustion, comprising an alkali metal borohydride and an ammonium salt

• US 20030051785A1
• Filed: 04/08/2002
• Published: 03/20/2003
• Est. Priority Date: 04/10/2001
• Status: Abandoned Application

• Current Assignee: Snpe Materiaux Energetiques (Government of France)
• Original Assignee: Snpe Materiaux Energetiques (Government of France)
• Inventors: Gauthier, Corinne, Perut, Christian, Roller, Denis
• Application Number:
  US10/117,915
• Publication Number:
  US 20030051785A1
• Time in Patent Office: Days
• US Class Current: 149/22
• CPC Class Codes: C01B 3/065 from a hydride
• CPC Class Codes: C06B 43/00 Compositions characterised by explosive or thermic constituents not provided for in groups C06B25/00 - C06B41/00
• CPC Class Codes: C06B 47/10 a component containing free boron, an organic borane or a binary compound of boron, except with oxygen
• CPC Class Codes: H01M 8/065 by dissolution of metals or alloys; by dehydriding metallic substances
• CPC Class Codes: Y02E 60/36 Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

The invention relates to solid compositions that can decompose generating hydrogen in a self-sustaining combustion reaction after this reaction has been initiated by an appropriate heat source. These compositions comprise an alkali metal borohydride and an oxidizing mineral ammonium salt of formula NH₄Y, in which Y represents a group consisting only of nitrogen and oxygen. The ratio of the weight content of alkali metal borohydride to the weight content of the salt of general formula NH₄Y is between 1 and 4. Thus, high hydrogen mass yields are obtained, of around 8 to 14%, thereby making it possible to reduce the size and the weight of the hydrogen generators used in certain systems, especially in proton exchange membrane fuel cells.

Claims

1. Solid composition that can decompose generating hydrogen in a self-sustaining combustion reaction after this reaction has been initiated by an appropriate heat source, the said composition comprising an alkali metal borohydride and an oxidizing mineral ammonium salt, characterized in that the said salt satisfies the general formula NH₄Y in which Y represents a group consisting only of nitrogen and oxygen, and in that the ratio of the weight content of alkali metal borohydride to the weight content of the salt of general formula NH₄Y is between 1 and 4.

2. Solid composition according to claim 1, characterized in that Y represents the nitrate or dinitramide group.

3. Solid composition according to claim 1, characterized in that it is in the form of a compact material

4. Solid composition according to claim 3, characterized in that the compact material is a pellet or a particle.

5. Solid composition according to claim 1, characterized in that it contains no organic matter.

6. Solid composition according to claim 1, characterized in that it essentially consists of an alkali metal borohydride and a salt of general formula NH₄Y.

7. Solid composition according to claim 1, characterized in that the sum of the weight contents of alkali metal borohydride and of the salt of general formula NH₄Y is greater than or equal to 90% compared with the total weight of the composition.

8. Solid composition according to claim 1, characterized in that the alkali metal borohydride is chosen from the group consisting of lithium borohydride, sodium borohydride and mixtures thereof.

10. Hydrogen generator intended to supply a proton exchange membrane fuel cell with hydrogen, characterized in that this generator is a pyrotechnic generator comprising a solid composition according to claim 1.

11. Proton exchange membrane fuel cell using hydrogen as fuel, comprising at least one electrochemical cell and a hydrogen generator connected to the anode compartment of the electrochemical cell, characterized in that this hydrogen generator is a pyrotechnic generator according to claim 10.

9. Process for generating hydrogen by self-sustaining combustion of a solid composition comprising an alkali metal borohydride and an oxidizing mineral ammonium salt, characterized in that:

a homogenous, pulverulent or granular, solid composition comprising an alkali metal borohydride and an ammonium salt of general formula NH₄Y, in which Y represents a group consisting only of nitrogen and oxygen, the ratio of the weight content of alkali metal borohydride to the weight content of the salt of general formula NH₄Y being between 1 and 4, is produced;

next, this composition is agglomerated using appropriate means so as to form a compact material;

the compact material is placed in a combustion chamber; and

the combustion of the compact material is initiated using an appropriate heat source, which causes the self-sustaining combustion of the material with generation of hydrogen until the end of combustion.