Fuel blends for hydrogen generators

Abstract

The present invention relates to improved aqueous fuels for hydrogen generators and a method for using them in the production of hydrogen. The present invention also relates to a system of using the subject aqueous fuels to generate hydrogen gas for use in a fuel cell or other device. The subject fuels contain a mixture of boron hydrides, at least one of which is a metal salt, including metal borohydrides, higher boranes and metal higher boron hydrides. The subject aqueous fuels contain a mixture of boron hydrides having a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.4 or between 0.6 and 0.99. Preferred fuels contain a mixture of boron hydrides having an ( + IC) to boron ratio between 0.2 and 0.3 or between 0.7 and 0.8. Mixtures containing a metal borohydride also contain a metal hydroxide to stability it against premature hydrolysis in the aqueous fuel media.

1 . An aqueous fuel for a hydrogen generator comprising an aqueous or hydroalcoholic solution or slurry of a mixture of boron hydrides including at least one boron hydride salt with a positive ion selected from the group consisting of alkali metal, alkaline earth metal and aluminum cations, said mixture of boron hydrides having a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.4 or between 0.6 and 0.99.  
     
     
         2 . An aqueous fuel in accordance with  claim 1 , wherein said mixture of boron hydrides has a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.3 or between 0.7 and 0.8.  
     
     
         3 . An aqueous fuel in accordance with  claim 1 , wherein said boron hydrides are selected from the group consisting of borohydride salts (MBH 4 ), triborohydride salts (MB 3 H 8 ), decahydrodecaborate salts (M 2 B 10 H 10 ), tridecahydrodecaborate salts (MB 10 H 13 ), dodecahydrododecaborate salts (M 2 B 12 H 12 ), octadecahydroicosaborate salts (M 2 B 20 H 18 ), and decaborane(14) (B 10 H 14 ), wherein M is selected from the group consisting of alkali metal, alkaline earth metal and aluminum cations.  
     
     
         4 . An aqueous fuel in accordance with  claim 1 , wherein said mixture contains a borohydride salt with a positive ion selected from the group consisting of sodium, lithium and potassium cations.  
     
     
         5 . An aqueous fuel in accordance with  claim 4 , wherein said mixture additionally contains a stabilizer for said borohydride salt in aqueous media, said stabilizer comprising a hydroxide selected from the group consisting of the hydroxides of sodium, lithium and potassium.  
     
     
         6 . An aqueous fuel in accordance with  claim 5 , wherein said borohydride salt is sodium borohydride and said stabilizer is sodium hydroxide.  
     
     
         7 . An aqueous fuel in accordance with  claim 3 , wherein said boron hydride mixture comprises a borohydride salt and decaborane, said fuel also containing a stabilizer for said borohydride salt in aqueous media, said stabilizer comprising a hydroxide selected from the group consisting of the hydroxides of sodium, lithium and potassium.  
     
     
         8 . An aqueous fuel in accordance with  claim 7 , wherein said boron hydride mixture comprises sodium borohydride and decaborane, and said stabilizer is sodium hydroxide.  
     
     
         9 . An aqueous fuel in accordance with  claim 3 , wherein said boron hydride mixture comprises a triborohydride salt and a dodecahydrododecaborate salt.  
     
     
         10 . An aqueous fuel in accordance with  claim 9 , wherein said triborohydride salt is potassium triborohydride and said dodecahydrododecaborate salt is magnesium dodecahydrododecaborate.  
     
     
         11 . An aqueous fuel in accordance with  claim 3 , wherein said boron hydride mixture comprises a borohydride salt and a dodecahydrododecaborate salt, said fuel also containing a stabilizer for said borohydride salt in aqueous media, said stabilizer comprising a hydroxide selected from the group consisting of the hydroxides of sodium, lithium and potassium.  
     
     
         12 . An aqueous fuel in accordance with  claim 11 , wherein said boron hydride salt is sodium borohydride, said dodecahydrododecaborate salt is sodium dodecahydrododecaborate, and said stabilizer is sodium hydroxide.  
     
     
         13 . An aqueous fuel in accordance with  claim 3 , wherein said boron hydride mixture is a borohydride salt and a triborohydride salt, said fuel also containing a stabilizer for said borohydride salt in aqueous media, said stabilizer comprising a hydroxide selected from the group consisting of the hydroxides of sodium, lithium and potassium.  
     
     
         14 . An aqueous fuel in accordance with  claim 13 , wherein said borohydride salt is sodium borohydride, said triborohydride salt is sodium triborohydride, and said stabilizer is sodium hydroxide.  
     
     
         15 . A method of generating hydrogen gas comprising contacting an aqueous fuel comprising an aqueous or hydroalcoholic solution or slurry of a mixture of boron hydrides including at least one boron hydride salt with a positive ion selected from the group consisting of alkali metal, alkaline earth metal, and aluminum cations, said mixture of boron hydrides having a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.4 or between 0.6 and 0.99 with a hydrogen generating catalyst selected from the group consisting of acids and transition metals.  
     
     
         16 . A method of generating hydrogen gas in accordance with  claim 15 , wherein said mixture of boron hydrides has a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.3 or between 0.7 and 0.8.  
     
     
         17 . A method of generating hydrogen gas in accordance with  claim 15 , wherein said boron hydrides are selected from the group consisting of borohydride salts (MBH 4 ), triborohydride salts (MB 3 H 8 ), decahydrodecaborate salts (M 2 B 10 H 10 ), tridecahydrodecaborate salts (MB 10 H 13 ), dodecahydrododecaborate salts (M 2 B 12 H 12 ), octadecahydroicosaborate salts (M 2 B 20 H 18 ), and decaborane(14) (B 10 H 14 ), wherein M is selected from the group consisting of alkali metal, alkaline earth metal and aluminum cations.  
     
     
         18 . A method of generating hydrogen gas in accordance with  claim 15 , wherein said mixture contains a borohydride salt wherein M is selected from the group consisting of sodium, lithium and potassium.  
     
     
         19 . A method of generating hydrogen gas in accordance with  claim 18 , wherein said mixture additionally contains a stabilizer for said borohydride salt in aqueous media, said stabilizer comprising a hydroxide of sodium, lithium and potassium.  
     
     
         20 . A method of generating hydrogen gas in accordance with  claim 15 , wherein the catalyst is an acid selected from the group consisting of hydrochloric acid, sulfuric acid, and phosphoric acid.  
     
     
         21 . A method of generating hydrogen gas in accordance with  claim 1 , wherein the catalyst comprises one or more transition metals selected from the metal families of nickel, cobalt and iron.  
     
     
         22 . A method of generating hydrogen gas in accordance with  claim 21 , wherein the catalyst is ruthenium, cobalt or mixtures thereof.  
     
     
         23 . A hydrogen generation system, comprising 
 (a) an aqueous fuel comprising an aqueous or hydroalcoholic solution or slurry of a mixture of boron hydrides including at least one boron hydride salt with a positive ion selected from the group consisting of alkali metal, alkaline earth metal and aluminum cations, said mixture of boron hydrides having a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.4 or between 0.6 and 0.99;    (b) a hydrogen generating catalyst selected from the group consisting of acids and transition metals, and    (c) means to contact the aqueous fuel with the catalyst thereby generating hydrogen.    
     
     
         24 . A method of generating hydrogen gas in accordance with  claim 23 , wherein said mixture of boron hydrides has a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.3 or between 0.7 and 0.8.  
     
     
         25 . A hydrogen generation system in accordance with  claim 23 , wherein said boron hydrides are selected from the group consisting of borohydride salts (MBH 4 ), triborohydride salts (MB 3 H 8 ), decahydrodecaborate salts (M 2 B 10 H 10 ), tridecahydrodecaborate salts (MB 10 H 13 ), dodecahydrododecaborate salts (M 2 B 12 H 12 ), octadecahydroicosaborate salts (M 2 B 20 H 18 ), and decaborane(14) (B 10 H 14 ), wherein M is selected from the group consisting of alkali metal, alkaline earth metal and aluminum cations.  
     
     
         26 . A hydrogen generation system in accordance with  claim 23 , wherein said mixture contains a borohydride salt with a positive ion selected from the group consisting of sodium, lithium and potassium cations.  
     
     
         27 . A hydrogen generation system in accordance with  claim 23 , wherein the hydrogen generating catalyst is an acid selected from the group consisting of hydrochloric acid, sulfuric acid, and phosphoric acid, and said acid and the aqueous fuel are stored in separate containers.  
     
     
         28 . A hydrogen generation system in accordance with  claim 23 , wherein the hydrogen generating catalyst comprises a substrate having molecules of a transition metal bound thereto, entrapped within, and/or coated thereon and said means to contact comprises a containment system for said catalyst whereby the catalyst can be moved into and out of contact with the aqueous fuel.  
     
     
         29 . A hydrogen generation system in accordance with  claim 23 , additionally containing a gas-liquid separator to separate hydrogen from the effluent thereof.  
     
     
         30 . A hydrogen generation system in accordance with  claim 23 , wherein at least a portion of the water in said aqueous fuel is obtained from the reaction product of a hydrogen-consuming device, said device being operably connected with said system.  
     
     
         31 . A hydrogen generation system in accordance with  claim 30 , wherein the hydrogen-consuming device is selected from the group consisting of a fuel cell, a combustion engine, a gas turbine, and combinations thereof.  
     
     
         32 . A hydrogen generation system, comprising 
 (a) a fuel blend including at least one boron hydride salt with a positive ion selected from the group consisting of alkali metal, alkaline earth metal, and aluminum cations;    (b) an accelerant comprising an acidic polyhedral boron hydride salts selected from the group consisting of the hydronium and ammonium salts of polyhedral boron hydrides, wherein said mixture of boron hydrides and accelerant has a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.4 or between 0.6 and 0.99; and    (c) means to contact the fuel blend and water with the accelerant thereby generating hydrogen.    
     
     
         33 . A method of generating hydrogen gas in accordance with  claim 32 , wherein said mixture of boron hydrides and accelerant has a positive ionic charge ( + IC) to boron ratio of between 0.2 and 0.3 or between 0.7 and 0.8.  
     
     
         34 . A hydrogen generation system in accordance with  claim 35 , wherein said boron hydrides are selected from the group consisting of borohydride salts (MBH 4 ), triborohydride salts (MB 3 H 8 ), decahydrodecaborate salts (M 2 B 10 H 10 ), tridecahydrodecaborate salts (MB 10 H 13 ), dodecahydrododecaborate salts (M 2 B 10 H 12 ), octadecahydroicosaborate salts (M 2 B 20 H 18 ), and decaborane(14) (B 10 H 14 ), wherein M is selected from the group consisting of alkali metal, alkaline earth metal and aluminum cations.  
     
     
         35 . A hydrogen generation system in accordance with  claim 32 , wherein said accelerant is H 2 B 12 H 12 .  
     
     
         36 . A hydrogen generation system in accordance with  claim 32 , wherein said accelerant is (NH 4 ) 2 B 10 H 10 .  
     
     
         37 . A hydrogen generation system in accordance with  claim 32 , wherein said mixture contains a borohydride salt wherein the positive ion is selected from the group consisting of sodium, lithium and potassium.  
     
     
         38 . A hydrogen generation system in accordance with  claim 32 , wherein at least a portion of the water is obtained from the reaction product of a hydrogen-consuming device, said device being operably connected with said system.  
     
     
         39 . A hydrogen generation system in accordance with  claim 38 , wherein the hydrogen-consuming device is selected from the group consisting of a fuel cell, a combustion engine, a gas turbine, and combinations thereof.