System for hydrogen generation
View Patent ↗The present invention relates to an improvement in a system for the generation of hydrogen by contacting an aqueous solution of a metal hydride salt with a hydrogen generation catalyst. In particular, the present invention relates to the incorporation within the system of a recycle line of water condensed from the fluid product to the feed line to be contacted with the catalyst. the internal recycle line permits the use of a more concentrated solution of metal hydride as it is diluted by the recycle line prior to contact with the catalyst.
1. A hydrogen generation system comprising:
(a) a fuel supply reservoir containing an aqueous solution of at least one metal hydride;
(b) a fuel pump configured to withdraw said solution and contact it with a hydrogen generation catalyst thereby generating a fluid product stream comprising hydrogen, water and a salt of said metal;
(c) a gas-liquid separator configured to separate said fluid stream into a gaseous product comprising hydrogen and water vapor, and a liquid comprising water and said metal salt;
(d) a condenser in fluid flow communication with said gaseous product to condense water therefrom;
(e) a condensate recovery zone configured to recover said condensed water; and
(f) a mixing zone configured to combine said condensed water with said aqueous solution of metal hydride withdrawn from said reservoir thereby diluting said solution prior to contacting said solution with the hydrogen generation catalyst.
2. A hydrogen generation system in accordance with claim 1 , wherein said mixing zone is upstream of said fuel pump.
3. A hydrogen generation system in accordance with claim 1 , wherein said mixing zone is located in fluid flow between said fuel pump and the hydrogen generation catalyst.
4. A hydrogen generation system in accordance with claim 3 , additionally containing a pump configured to withdraw condensed water from said condensate recovery zone and introduce it into said mixing zone.
5. A hydrogen generation system in accordance with claim 1 , additionally containing a valve upstream of the mixing zone configured to permit alternative flow of said metal hydride solution and condensed water from said condensate zone into said mixing zone.
6. A hydrogen generation system in accordance with claim 1 , configured such that the concentration of said metal hydride in the fuel supply reservoir is above the maximum solubility of the hydride and a portion thereof is in suspension.
7. A hydrogen generation system in accordance with claim 6 , configured such that sufficient condensed water is added to the mixing zone so that all of the metal hydride is in dilute solution when it contacts the hydrogen generation catalyst.
8. A hydrogen generation system in accordance with claim 6 , additionally including mixing means in the fuel supply reservoir to maintain uniformity of said suspension.
9. A hydrogen generation system in accordance with claim 1 , configured such that said aqueous solution of metal hydride solution further comprises a sufficient amount of an alkaline stabilizing agent to provide a pH thereof at about pH 7.
10. A hydrogen generation system in accordance with claim 9 , wherein the alkaline stabilizing agent is a hydroxide.
11. A hydrogen generation system in accordance with claim 9 , wherein the cation portion of the alkaline stabilizing agent is the same as the cation portion of said metal hydride.
12. A hydrogen generation system in accordance with claim 11 , wherein said cation is sodium ion.
13. A hydrogen generation system in accordance with claim 12 , wherein the alkaline stabilizing agent is sodium hydroxide and the metal hydride is sodium borohydride.
14. A hydrogen generation system in accordance with claim 1 , further comprising a containment system configured to separate the catalyst from said salt of the metal in the fluid product stream.
15. A hydrogen generation system in accordance with claim 14 , wherein said containment system comprises a cylinder having said catalyst therein.
16. A hydrogen generation system in accordance with claim 1 , wherein said hydrogen generation catalyst comprises a transition metal selected from the group consisting of ruthenium, iron, cobalt, nickel, copper, manganese, rhodium, rhenium, platinum, palladium, chromium, silver, osmium, iridium, borides thereof, alloys thereof, and mixtures thereof.
17. A hydrogen generation system in accordance with claim 1 , wherein the metal hydride is selected from the group consisting of sodium borohydride, lithium borohydride, potassium borohydride, ammonium borohydride, and mixtures thereof.
18. A hydrogen generation system in accordance with claim 1 , wherein the catalyst is a supported catalyst.