Borohydride fuel compositions and methods

Abstract

Solid self-stabilized borohydride fuel compositions, fuel cartridges, related methods of preparation and hydrogen generation are provided. The fuel compositions comprise mixtures of at least one borohydride salt with a cation selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, preferably sodium borohydride, and at least one hydroxide salt with a cation selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, preferably sodium hydroxide.

1 . A solid fuel composition, comprising: 
 about 20 to about 99.7% by weight borohydride salt of formula M(BH 4 ) n , wherein M is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n corresponds to the charge of the selected M cation; and    a stabilizing amount of a hydroxide salt of formula M′(OH) n′ , wherein M′ is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n′ corresponds to the charge of the selected M′ cation.    
   
   
       2 . The composition of  claim 1 , wherein the borohydride and hydroxide salts are homogeneously distributed within the solid fuel composition.  
   
   
       3 . The composition of  claim 1 , wherein the hydroxide salt is present in an amount of about 0.3 to about 80% by weight.  
   
   
       4 . The composition of  claim 1 , wherein M and M′ are the same cation.  
   
   
       5 . The composition of  claim 1 , wherein the borohydride salt is selected from the group consisting of sodium borohydride, lithium borohydride, potassium borohydride, calcium borohydride, and mixtures thereof.  
   
   
       6 . The composition of  claim 1 , wherein the borohydride salt is hydrated.  
   
   
       7 . The composition of  claim 6 , wherein water is present in the solid fuel in an amount of about 1 to about 96% by weight of the borohydride salt.  
   
   
       8 . The composition of  claim 6 , wherein the borohydride salt is selected from the group consisting of sodium borohydride dihydrate, potassium borohydride trihydrate, potassium borohydride monohydrate, and mixtures thereof.  
   
   
       9 . The composition of  claim 1 , wherein the hydroxide salt is selected from the group consisting of calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, and mixtures thereof.  
   
   
       10 . The composition of  claim 9 , wherein the hydroxide salt is present in an amount of about 0.28 to about 800% by weight of the borohydride salt.  
   
   
       11 . The composition of  claim 1 , comprising a compacted solid fuel.  
   
   
       12 . The composition of  claim 11 , wherein the compacted solid fuel is in the shape of a tablet.  
   
   
       13 . The composition of  claim 11 , wherein the compacted solid fuel is in the shape of a caplet.  
   
   
       14 . The composition of  claim 11 , wherein the compacted solid fuel is in the shape of a granule.  
   
   
       15 . The composition of  claim 11 , wherein the compacted solid fuel has a shape selected from the group consisting of rectangular parallelepipeds and spheres.  
   
   
       16 . The composition of  claim 11 , wherein at least one surface of the compacted solid fuel is textured.  
   
   
       17 . The composition of  claim 11 , wherein at least one surface of the compacted solid fuel is scored.  
   
   
       18 . The composition of  claim 11 , further comprising a solid acid component and a solid carbonate component for producing carbon dioxide.  
   
   
       19 . The composition of  claim 18 , wherein the solid acid component is present in an amount of about 1 to about 10% by weight of the borohydride salt.  
   
   
       20 . The composition of  claim 18 , wherein the solid acid component is selected from the group consisting of citric acid, tartaric acid, fumaric acid, adipic acid, maleic acid, and oxalic acid.  
   
   
       21 . The composition of  claim 18 , wherein the solid carbonate component is selected from the group consisting of sodium carbonate, sodium bicarbonate, potassium carbonate, and magnesium carbonate.  
   
   
       22 . The composition of  claim 18 , wherein at least one of the solid acid component and the solid carbonate component is homogenously distributed within the solid fuel.  
   
   
       23 . The composition of  claim 18 , wherein at least one of the solid acid component and the solid carbonate component is present in a compressed pellet inside the solid fuel.  
   
   
       24 . The composition of  claim 11 , further comprising a disintegrant.  
   
   
       25 . The composition of  claim 24 , wherein the disintegrant is diammonium decahydrodecaborate.  
   
   
       26 . The composition of  claim 25 , when the disintegrant is present in an amount from about 0.1 to about 0.5% by weight of the borohydride salt.  
   
   
       27 . A stable fuel composition, comprising a mixture of 
 a borohydride salt of formula M(BH 4 ) n  and a hydroxide salt of formula M′(OH) n , wherein M and M′ are independently selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation,    wherein the composition upon reaction with water is characterized by the production of gas at a rate less than about 1 liter per kilogram of material per hour averaged over about a 7-hour period.    
   
   
       28 . The fuel composition of  claim 27 , wherein the borohydride salt is present in an amount of about 20 to about 99.7% by weight of the solid fuel composition.  
   
   
       29 . The fuel composition of  claim 27 , wherein the hydroxide salt is present in an amount of about 0.3 to about 80% by weight of the solid fuel composition.  
   
   
       30 . The fuel composition of  claim 27 , wherein the composition dissolves in aqueous solution at room temperature at a rate of about 0.05 g/mL/sec to about 0.5 g/mL/sec.  
   
   
       31 . The fuel composition of  claim 27 , wherein the fuel composition comprises a solid form unit selected from the group consisting of a caplet, a tablet, a granule, a parallelepiped, a sphere, and a cube.  
   
   
       32 . The fuel composition of  claim 31 , wherein at least one surface of the solid form unit is textured or scored.  
   
   
       33 . The fuel composition of  claim 31 , wherein the solid form unit has a density of about 0.7 g/mL to about 1.2 g/mL.  
   
   
       34 . The fuel composition of  claim 31 , wherein the solid form unit further comprises an effervescent component.  
   
   
       35 . The fuel composition of  claim 31 , wherein the solid form unit further comprises a disintegrating component.  
   
   
       36 . The fuel composition of  claim 31 , wherein the solid form unit further comprises a binder.  
   
   
       37 . The fuel composition of  claim 27 , wherein water is present in the composition in an amount of about 1 to about 96% by weight of the borohydride salt.  
   
   
       38 . The fuel composition of  claim 37 , wherein the borohydride salt is selected from the group consisting of sodium borohydride dehydrate, potassium borohydride trihydrate, potassium borohydride monohydrate, and mixtures thereof.  
   
   
       39 . The fuel composition of  claim 37 , wherein the hydroxide salt is selected from the group consisting of sodium hydroxide, lithium hydroxide, potassium hydroxide, and mixtures thereof.  
   
   
       40 . A method of preparing a compacted solid fuel composition for hydrogen generation, the method comprising: 
 providing a uniform mixture of about 20 to about 99.7% by weight borohydride salt of formula M(BH 4 ) n  and about 0.3 to about 80% by weight hydroxide salt of formula M′(OH) n , wherein M and M′ are independently selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation and ammonium cation; and    applying pressure to compact the mixture into at least one solid unit form having a density greater than the mixture.    
   
   
       41 . The method of  claim 40 , further comprising compacting the mixture in a mold to produce at least one solid unit form selected from the group consisting of a caplet, a tablet, a granule, a sphere, a parallelepiped, and a cube.  
   
   
       42 . The method of  claim 40 , wherein the borohydride salt is selected from the group consisting of sodium borohydride, lithium borohydride, potassium borohydride, calcium borohydride, and mixtures thereof.  
   
   
       43 . The method of  claim 40 , further comprising adding water to the mixture in an amount of about 1 to about 96% by weight of the borohydride salt.  
   
   
       44 . The method of  claim 40 , wherein the borohydride salt is a hydrated borohydride salt selected from the group consisting of sodium borohydride dihydrate, potassium borohydride trihydrate, potassium borohydride monohydrate, and mixtures thereof.  
   
   
       45 . The method of  claim 40 , wherein the hydroxide salt is selected from the group consisting of sodium hydroxide, lithium hydroxide, potassium hydroxide, and mixtures thereof.  
   
   
       46 . The method of  claim 40 , further comprising admixing a solid acid component and a solid carbonate component for producing carbon dioxide.  
   
   
       47 . The method of  claim 46 , wherein the solid acid component is present in an amount of about 1 to about 10% by weight of the borohydride salt.  
   
   
       48 . The method of  claim 45 , wherein the solid acid component is selected from the group consisting of citric acid, tartaric acid, fumaric acid, adipic acid, maleic acid, and oxalic acid.  
   
   
       49 . The method of  claim 45 , wherein the solid carbonate component is selected from the group consisting of sodium carbonate, sodium bicarbonate, potassium carbonate, and magnesium carbonate.  
   
   
       50 . The method of  claim 45 , further comprising homogenously distributing the solid acid component and the solid carbonate component within the mixture.  
   
   
       51 . The method of  claim 40 , further comprising admixing at least one of the solid acid component and the solid carbonate component as a compressed pellet in the mixture.  
   
   
       52 . The composition of  claim 34 , further comprising admixing a disintegrant with the mixture.  
   
   
       53 . The composition of  claim 52 , wherein the disintegrant is diammonium decahydrodecaborate.  
   
   
       54 . The composition of  claim 52 , when the disintegrant is present in an amount from about 0.1 to about 0.5% by weight of the borohydride salt.  
   
   
       55 . A method of generating hydrogen gas, comprising: 
 providing a solid fuel composition containing a homogeneous dispersion of about 20 to about 99.7% by weight borohydride salt of formula M(BH 4 ) n  and about 0.3 to about 80% by weight hydroxide salt of formula M′(OH) n , wherein M and M′ are independently selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation;    dissolving the solid fuel composition to prepare an aqueous fuel solution; and    contacting the aqueous fuel solution with a catalyst to produce hydrogen gas.    
   
   
       56 . The method of  claim 55 , wherein the solid fuel composition further comprises a solid acid component and a solid carbonate component for producing carbon dioxide.  
   
   
       57 . The method of  claim 56 , wherein the solid acid component is present in an amount of about 1 to about 10% by weight of the borohydride salt.  
   
   
       58 . The method of  claim 56 , wherein the solid acid component is selected from the group consisting of citric acid, tartaric acid, fumaric acid, adipic acid, maleic acid, and oxalic acid.  
   
   
       59 . The method of  claim 56 , wherein the solid carbonate component is selected from the group consisting of sodium carbonate, sodium bicarbonate, potassium carbonate, and magnesium carbonate.  
   
   
       60 . The method of  claim 55 , wherein the solid fuel composition further comprises a disintegrant.  
   
   
       61 . The method of  claim 60 , wherein the disintegrant is diammonium decahydrodecaborate.  
   
   
       62 . The method of  claim 60 , when the disintegrant is present in an amount from about 0.1 to about 0.5% by weight of the borohydride salt.  
   
   
       63 . The method of  claim 54 , wherein the catalyst is selected from the group consisting of metals of ruthenium, iron, cobalt, nickel, copper, manganese, rhodium, rhenium, platinum, palladium, and chromium, and salts of ruthenium, iron, cobalt, nickel, copper, manganese, rhodium, rhenium, platinum, palladium, and chromium.  
   
   
       64 . A compacted solid fuel composition for hydrogen generation, comprising about 20 to about 99.7% by weight sodium borohydride salt; 
 about 0.3 to about 80% by weight sodium hydroxide salt homogeneously interdispered with the sodium borohydride salt; and    wherein the compacted solid fuel composition is in a form selected from the group consisting of caplets, tablets, granules, spheres, parallelepipeds and cubes, and has a density of from about 0.7 to about 1.2 g/mL.    
   
   
       65 . The composition according to  claim 64 , further comprising a solid acid component and a solid carbonate component.  
   
   
       66 . The solid fuel composition of  claim 64 , wherein water is present in the solid fuel in an amount of about 1 to about 96% by weight of the borohydride salt.  
   
   
       67 . The solid fuel compositions of  claim 64 , wherein the borohydride salt is sodium borohydride dihydrate.  
   
   
       68 . The solid fuel composition of  claim 64 , wherein the hydroxide salt is present in an amount of about 1% to 50% of the borohydride salt.  
   
   
       69 . The solid fuel composition of  claim 64 , wherein the sodium borohydride is present in about 87 weight percent and the sodium hydroxide is present in about 13 weight percent.  
   
   
       70 . The solid fuel composition of  claim 64 , wherein the solid fuel further comprises an effervescent component.  
   
   
       71 . The solid fuel composition of  claim 64 , wherein the solid fuel further comprises a disintegrating component.  
   
   
       72 . The solid fuel composition of  claim 64 , wherein the solid form is scored or textured.  
   
   
       73 . The solid fuel composition of  claim 64 , wherein the composition is not subject to dangerous-when-wet classification and is characterized by the production of gas at a rate less than about 1 liter per kilogram of material per hour averaged over about a 7-hour period.  
   
   
       74 . A method of preparing a solid fuel composition for hydrogen generation, the method comprising: 
 providing a solution of about 2 to about 35% by weight borohydride salt of formula M(BH 4 ) n  and about 0.5 to about 40% by weight hydroxide salt of formula M′(OH) n , in water, wherein M and M′ are independently selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation and ammonium cation;    cooling said solution to produce a frozen solution; and    subliming the water from said frozen solution to produce a solid mixture substantially free of solvent.    
   
   
       75 . A solid fuel composition, comprising: 
 about 20 to about 99.7% by weight borohydride salt of formula M(BH 4 ) n , wherein M is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n corresponds to the charge of the selected M cation; and    a stabilizing amount of a hydroxide salt of formula M′(OH) n′ , wherein M′ is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n′ corresponds to the charge of the selected M′ cation, wherein the solid fuel composition has an X-Ray powder diffraction (XRPD) pattern with peaks at 25, 29, 41.5, 49 and 51.5 degrees 2-theta.    
   
   
       76 . A solid fuel composition, comprising: 
 about 20 to about 99.7% by weight borohydride salt of formula M(BH 4 ) n , wherein M is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n corresponds to the charge of the selected M cation; and    a stabilizing amount of a hydroxide salt of formula M′(OH) n′ , wherein M′ is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n′ corresponds to the charge of the selected M′ cation, and    wherein the ratio by weight of the borohydride salt to the hydroxide salt is less than about 40:1.    
   
   
       77 . A solid fuel composition, comprising: 
 at least two salts of formula M(BH 4 ) n  and M′(BH 4 ) n′ , wherein M and M′ are independently selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n and n′ correspond to the charge of the selected M and M′ cation, respectively; and    a stabilizing amount of a hydroxide salt of formula M″(OH) n″ , wherein M″ is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n″ corresponds to the charge of the selected M″ cation, and    wherein the solid fuel composition upon reaction with water produces gas at a rate less than about 1 liter per kilogram of material per hour averaged over about a 7-hour period.    
   
   
       78 . A method of preparing a solid fuel composition for hydrogen generation, the method comprising: 
 providing about 20 to about 99.7% by weight borohydride salt of formula M(BH 4 ) n , wherein M is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n corresponds to the charge of the selected M cation;    providing a stabilizing amount of a hydroxide salt of formula M′(OH) n′ , wherein M′ is selected from the group consisting of alkali metal cations, alkaline earth metal cations, aluminum cation, zinc cation, and ammonium cation, and n′ corresponds to the charge of the selected M′ cation, wherein the ratio by weight of the borohydride salt to the hydroxide salt is less than about 40:1l; and    mixing the borohydride salt and the hydroxide salt to form a substantially uniform mixture.    
   
   
       79 . The method of  claim 55 , wherein the solid fuel composition dissolves at a rate of about 0.05 g/mL/sec to about 0.5 g/mL/sec.  
   
   
       80 . The method of  claim 55 , wherein the solid fuel composition has a density of about 0.7 to about 1.2 g/mL.  
   
   
       81 . The method of  claim 55 , wherein the solid fuel composition has an x-ray powder diffraction (XRPD) pattern with peaks at 25, 29, 41.5, 49 and 51.5 degrees 2-theta.  
   
   
       82 . A fuel cartridge, comprising: 
 a housing for containing a solid fuel; and    a solid fuel composition according to  claim 1  contained within the housing.    
   
   
       83 . The composition of  claim 1 , wherein the hydroxide salt is selected from the group consisting of alkaline earth metal salts and alkaline metal salts.