Compositions and methods for hydrogen generation

Abstract

Hydrogen storage fuel compositions comprising a mixture of at least one chemical hydride compound and at least one compound, polymer, carboxylic acid or salt that acts as a water surrogate source, and methods for thermally initiated hydrogen generation from fuel compositions, are disclosed. The water surrogate source/chemical hydride compositions are preferably solids, and may be powders, caplets, tablets, pellets or granules, for example. The water surrogate source/chemical hydride compositions may comprise alternating layers of the chemical hydride and of the water surrogate source.

1 . A solid fuel composition comprising at least one chemical hydride and at least one carboxylic acid. 
     
     
         2 . The fuel composition of  claim 1 , wherein the at least one carboxylic acid comprises at least one hydroxyl group. 
     
     
         3 . The fuel composition of  claim 2 , wherein the carboxylic acid is selected from the group consisting of malic acid, tartaric acid, fumaric acid and citric acid. 
     
     
         4 . The fuel composition of  claim 1 , wherein the at least one carboxylic acid is fumaric acid. 
     
     
         5 . The fuel composition of  claim 1 , wherein the chemical hydride is a boron hydride selected from the group consisting of borohydride salts [M(BH 4 ) n ], triborohydride salts [M(B 3 H 8 ) n ], decahydrodecaborate salts [M 2 (B 10 H 10 ) n ], tridecahydrodecaborate salts [M(B 10 H 13 ) n ], dodecahydrododecaborate salts [M 2 (B 12 H 12 ) n ], and octadecahydroicosaborate salts [M 2 (B 20 H 18 ) n ], where M is an alkali metal cation, alkaline earth metal cation, aluminum cation, zinc cation, ammonium cation, alkyl ammonium cation, dialkyl ammonium cation, triakyl ammonium cation, tetraalkyl ammonium cation, or phosphonium cation, and n is equal to the charge of the cation. 
     
     
         6 . The fuel composition of  claim 5  further comprising a stabilizer. 
     
     
         7 . The fuel composition of  claim 1 , wherein the chemical hydride comprises a borane compound. 
     
     
         8 . The fuel composition of  claim 7 , wherein the borane compound is selected from the group consisting of decaborane(14) (B 10 H 14 ), ammonia borane compounds of formula NH x BH y , and NH x RBH y , wherein x and y are independently selected from 1 to 4, and wherein R is a methyl or ethyl group. 
     
     
         9 . The fuel composition of  claim 1 , wherein the chemical hydride is a hydride salt selected from the group consisting of hydrides of alkali metals and alkaline earth metals. 
     
     
         10 . The fuel composition of  claim 1 , wherein the chemical hydride is an aluminum hydride selected from the group consisting of alane (AlH 3 ) and aluminum hydride salts. 
     
     
         11 . The fuel composition of  claim 10 , wherein the aluminum hydride salts have the formula M(AlH 4 ) n , where M is an alkali metal cation, alkaline earth metal cation, aluminum cation, zinc cation, or ammonium cation, and n is equal to the charge of the cation. 
     
     
         12 . The fuel composition of  claim 1 , wherein the composition is in a form selected from the group consisting of granules, pellets, gel, tablets and powder, or a combination thereof. 
     
     
         13 . The fuel composition of  claim 1 , wherein the composition is in the form of a composite comprising at least one layer of the at least one chemical hydride and at least one layer of the carboxylic acid. 
     
     
         14 . The fuel composition of  claim 1 , further comprising a hydrolysis catalyst. 
     
     
         15 . The fuel composition of  claim 14 , wherein the hydrolysis catalyst comprises a material selected from the group consisting of chloride salts of cobalt, chloride salts of nickel, chloride salts of ruthenium, chloride salts of rhodium, chloride salts of platinum, and chloride salts of copper. 
     
     
         16 . A solid fuel composition, comprising:
 at least one chemical hydride;   at least one carboxylic acid; and   a hydrolysis catalyst.   
     
     
         17 . The fuel composition of  claim 16 , wherein the hydrolysis catalyst is a metal salt. 
     
     
         18 . The fuel composition of  claim 17 , wherein the metal salt is selected from the group consisting of chloride salts of cobalt, chloride salts of nickel, chloride salts of ruthenium, chloride salts of rhodium, chloride salts of platinum, and chloride salts of copper. 
     
     
         19 . The fuel composition of  claim 16 , wherein the at least one carboxylic acid is selected from the group consisting of malic acid, tartaric acid, fumaric acid, and citric acid. 
     
     
         20 . A process for generating hydrogen, comprising:
 providing a mixture of at least one chemical hydride and at least one carboxylic acid; and heating the mixture to generate hydrogen.   
     
     
         21 . The process of  claim 20 , wherein the at least one chemical hydride comprises sodium borohydride, lithium borohydride, lithium hydride, or combinations thereof. 
     
     
         22 . The fuel composition of  claim 20 , wherein the carboxylic acid is selected from the group consisting of malic acid, tartaric acid, fumaric acid, and citric acid. 
     
     
         23 . The process of  claim 20  further comprising heating the mixture to a temperature of between about 40 to about 350° C. 
     
     
         24 . The process of  claim 20  further comprising heating the mixture to a temperature above about 100° C. 
     
     
         25 . The process of  claim 20  further comprising heating the mixture to a temperature above about 130° C.