# Patent

## Title
Cartridge for controlled production of hydrogen

## Abstract

A reaction hydrogen production control mechanism is provided that includes, a solid sodium borohydride mixture, a liquid fuel reactant, at least one liquid delivery medium (LDM), a movable boundary interface (MBI) and a reaction zone, where the MBI is disposed to provide a constant contact between a reacting surface of the solid fuel mixture and the primary LDM to form the reaction zone. A reaction in the reaction zone includes a hydrolysis reaction. The MBI moves according to a spring, gas pressure, or an elastic membrane. Product paths are disposed to transfer reactants from the system. The product paths can include a channel on a surface of the solid fuel mixture, a channel disposed through the solid fuel mixture, a channel disposed about the solid fuel mixture, a contained region disposed about the solid fuel mixture, or a conduit abutting the solid fuel mixture.

## Background
This application is a continuation of U.S. patent application Ser. No. 12/803,965, filed Jul. 9, 2010, which is hereby expressly incorporated by reference as if fully set forth herein, in its entirety.


FIELD OF THE INVENTION
The invention relates to hydrogen production. In particular, the invention relates to managing the production of hydrogen from a sodium borohydride reaction.
BACKGROUND OF THE INVENTION
Hydrogen gas can be produced from a sodium borohydride (SBH) reaction, which provides a compact, high-density, controllable source of hydrogen gas. When reacted with water, in the presence of a suitable catalyst, the hydrogen complexes can provide a sizeable hydrogen gas yield by weight.
When SBH is combined with water, an exothermic reaction occurs that does not require the addition of heat or high pressure.
Adding water to SBH results in a crust layer on the surface due to production of the reactant product. As the crust layer grows, the water is less able to penetrate it to react with the unreacted SBH, restricting or even stopping the hydrogen production.
What is needed is a hydrogen production system that provides hydrogen gas where the reactant product is propagated away from the reaction zone according to forces provided by the produced hydrogen gas.
SUMMARY OF THE INVENTION
To overcome the shortcomings in the prior art, the current invention provides a reaction control mechanism that includes, a solid fuel mixture, a liquid fuel reactant, a primary liquid delivery medium (LDM), a movable boundary interface (MBI) and a reaction zone, where the MBI is disposed to provide a constant contact between a reacting surface of the solid fuel mixture and the primary LDM to form the reaction zone.
In one aspect of the invention, the reaction zone includes a reaction product path disposed to remove reaction products from the reaction zone. In another aspect, the reaction product path can include at least one channel disposed on a surface of the solid fuel mixture, at least one channel disposed through the solid fuel mixture, at least one helix channel disposed about the solid fuel mixture, a contained region disposed about the solid fuel mixture, or at least one conduit abutting the solid fuel mixture. Further, the reaction product path can include guides disposed in the reaction product path, where the guides are disposed to provide the liquid fuel reactant to the reaction zone, where a secondary LDM is disposed to provide the liquid fuel reactant independently from the primary LDM.
In another aspect of the invention a reaction in the reaction zone includes a hydrolysis reaction.
In a further aspect of the invention, the solid fuel mixture includes at least solid sodium borohydride (SBH).
According to another aspect of the invention, the MBI moves according to a physical moving element providing a force, where the force can be from a spring, gas pressure, or an elastic membrane. In one aspect, the elastic membrane envelops the solid fuel mixture.
In yet another aspect of the invention, the primary LDM is a stationary LDM.
In a further aspect, the primary LDM receives a compression force from the MBI.
According to one aspect of the invention, the primary LDM provides liquid to a reaction product path disposed between a surface of the solid fuel mixture and the MBI, wherein the reaction product path is disposed to transfer reactants to the reaction zone of the MBI and transfer products from the reaction zone of the MBI. In one aspect, the reaction product path can include at least one channel disposed on a surface of the solid fuel mixture, at least one channel disposed through the solid fuel mixture, at least one helix channel disposed about the solid fuel mixture, a contained region disposed about the solid fuel mixture, or at least one conduit abutting the solid fuel mixture. In another aspect, the MBI is an elastic membrane disposed to envelope the solid fuel mixture, where when the reactants are present in the reaction product path the elastic membrane is disposed to apply a pressure on the reactants to propagate the reactant along the reaction product path. In a further aspect, the elastic membrane pressure applied to the reactant is a variable pressure.
According to another aspect of the invention, a rate of the reaction is controlled by a rate of liquid provided by the primary LDM.
In a further aspect of the invention, a reaction product exiting the reaction zone includes a combination of a partially reacted liquid fuel reactant and the solid fuel mixture.
According to one aspect of the invention, the reaction control mechanism further includes a secondary LDM, where the secondary LDM is disposed in a reaction product path to control an overall reaction stoichiometry. The reaction stoichiometry can include a ratio of produced hydrogen to liquid fuel flow. Further, the secondary LDM is located in a reaction product path exiting the reaction zone.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic drawing of a hydrogen generation system that includes a moveable barrier interface, according to the current invention.
FIGS. 2a-2b show schematic drawings hydrogen generation systems having a moving boundary interface with forces applied, according to the current invention.
FIGS. 3a-3b show schematic drawings of hydrogen generation systems that include an elastic membrane moveable barrier interface enveloping the solid fuel mixture, according to the current invention.
FIG. 4 shows the SBH hydrolysis reaction at one side of a cylindrical fuel with the reaction products guided externally around the fuel body, according to the current invention.
FIGS. 5a-5c show the hydrogen generation systems having the MBI and a fuel mixture with a through internal conduit, according to the current invention.
FIGS. 6a-6c show exemplary forms of the internal conduits and outside through holes in a radial direction, according to the current invention.
FIG. 7 shows an exemplary embodiment of the invention.
FIGS. 8a-8c show exemplary embodiments of dimensions and patterns of the product guide, according to the current invention.



DETAILED DESCRIPTION
Although the following detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will readily appreciate that many variations and alterations to the following exemplary details are within the scope of the invention. Accordingly, the following preferred embodiment of the invention is set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.
According to the current invention, as shown in FIG. 1, a hydrogen generation system 100 includes a moving boundary interface (MBI) 102 that ensures a constant contact between a solid fuel 104 and a liquid delivery medium (LDM) 106, where the region of constant contact between the solid fuel 104 and the liquid LDM 106 is a reaction zone 108. The MBI 102 can either physically bring the reacting surface of a solid fuel 104 in contact with a stationary LDM 106, or bring an LDM 106 in contact with the varying contour of the reacting surface of a solid fuel 104. Movement of the MBI 102 can be accomplished by using an applied force that can include a spring force, gas (preferably H2) pressure, or elastic membrane.
Hydrogen generation systems 100 having the MBI 102, according to one aspect of the current invention, use compression force on a side of a solid fuel mixture 104. A compression force can be applied either to the side close to reaction zone 108 or the opposite side of the fuel mixture 104 using spring force, gas pressure or elastic membrane force, and the rate of the reaction is controlled by a rate of liquid provided by the primary LDM 106. FIGS. 2a-2b show examples of a hydrogen generation system 100 that utilizes compression forces in order to maintain a constant contact between LDM 106, providing liquid fuel reactant, 110 and the unreacted surface of the solid fuel 104, where the solid fuel 104 can be a sodium borohydride (SBH) fuel mixture. FIG. 2a shows one embodiment of the invention, where a compression force 112 is applied to the end of the system 100 that is opposite of the LDM 106, Alternatively, FIG. 2b shows compression force 112 is applied to the end of the system 100 of the LDM 106. At the reaction zone 108, hydrolysis occurs and reactant products are generated. According to the current invention, the constant compression between the LDM 106 and the surface of the solid fuel mixture 104 pushes the reactant product away from the reaction zone 108 and maintains continuous contact or the LDM 106 and the unreacted portion of the fuel mixture 104.
Other embodiments of the current invention use an elastic membrane to apply compression force around a solid fuel mixture 104. When a fuel mixture 104 is consumed and decreases in its volume, the elastic membrane MBI 102 shrinks and maintains its continuous contact to the surface of a fuel mixture 104. FIGS. 3a-3b show the embodiment of the invention that includes an elastic membrane MBI 102 that envelops the solid fuel mixture 104 and LDM 106 to maintain contact between the two elements. According the current embodiment, prior to SBH hydrolysis, the elastic membrane MBI 102 tightly encloses the solid fuel mixture 104. An LDM 106 is disposed between the surface of the fuel mixture 104 and the elastic MBI 102 to provide liquid reactant for forming a reaction zone 108, where when a liquid reactant from the LDM 106 is pumped into the system 100, the reaction occurs at the reaction zone 108. As the reaction progresses further, the volume of the fuel mixture 104 decreases, as show in FIG. 3b since the reactant products 114 are continuously pushed away from the reaction zone 108. The elastic membrane 102 shrinks over this varying contour of the fuel mixture 104, providing a continuous contact between the surface of the fuel mixture 104 and the LDM 106. A desired material to form an elastic MBI 102 conforms to the surface of a shrinking fuel mixture 104. Exemplary elastic MBI 102 materials can include, any elastic or rubbery materials (such as latex, silicone, viton, polyurethane, neoprene, buna-N, PTFE, ePTFE, perfluoroelastomer, fluorosilicone, Atlas, or Hytrel . . . etc), elastic fabrics, heat shrinkable fabrics, or spring sheets.
When a non-liquid fuel is employed and the hydrolysis reaction is induced at any surface of the solid fuel 104, the hydrolysis products need to be continuously removed from a reaction zone 108 to ensure a clean contact between an LDM 106 and the unreacted surface of the solid fuel 104. Providing clear and fabricated pathways for product removal 114 prevents any unexpected failure such as uncontrolled pressure buildup due to the product clogging, the entry disruption of liquid reactants, or the uncontrolled form-factor dismantling of a solid fuel 104. According to another aspect of the current invention, pathways for product removal 114 are provided. Hydrolysis products can be removed from a reaction zone 108 in multiple ways, where some exemplary embodiments are provided herein. For example, FIG. 4 shows when SBH hydrolysis reaction occurs at one side of a cylindrical fuel 104, its resulting products can be guided externally 114 around the fuel body 104.
FIGS. 5a-5c show a hydrogen generation system 100 having the MBI 102 and a fuel mixture 104 with a through internal conduit 116. As liquid reactant 110 is provided to the hydrogen generation system 100 through the LDM 106, the MBI 102 has an applied force, as described above, applied to the MBI 102, the reaction zone 108 produces the hydrogen gas and reactant products 114. The embodiment of FIGS. 5a-5c shows an internal conduit 116 for moving the reactant products 114 out of the solid fuel 104, where the reaction zone 108 is kept at an optimum for providing hydrogen gas.
According to the current invention, the internal conduits 116 are provided in many forms. Some exemplary forms include internal conduits connected to outside through holes in a radial direction, as shown in FIGS. 6a-6c, where the LDM 106, provides liquid reactant 110, and the MBI 102 is forced against the solid fuel 104 to promote a reaction zone 108. The reaction in hydrogen generation system 100 outputs hydrogen gas and reactant products 114, where the reactant products 114 are forced out of solid fuel 104 through the internal conduits 116 that can include the through and radial internal conduits 116. FIGS. 6b and 6c show the solid fuel element 104 with the internal conduits 116, where liquid reactant 110 is provide to the reaction zone 108 (not shown for illustrative purposes) and the reactant products 114 exit through the radial internal conduits 116, according to one aspect of the current invention.
In another embodiment of the invention a secondary LDM is added to the system 100. According to the invention, the effective reaction zone 108 may change with increasing utilization of the solid fuel mixture 104. As the solid fuel mixture 104 is consumed, the length of the reaction product guide (see FIGS. 8a-8c), and in some embodiments also the area of the reaction zone 108, decreases due to shrinking volume of the unreacted solid fuel mixture 104. This leads to variations in reaction stoichiometry (amount of hydrogen flow per liquid fuel flow). For optimum hydrogen fuel utilization and product separation it is beneficial to adjust the overall reaction stoichiometry by implementing a secondary LDM 118, as shown in FIG. 7. Here, FIG. 7 shows the embodiment of the invention that includes an elastic membrane MBI 102 that envelops the solid fuel mixture 104. A primary LDM 106 is disposed between the surface of the fuel mixture 104 and the elastic MBI 102 to provide liquid reactant 110 for forming a reaction zone 108, where when a liquid reactant 110 from the primary LDM 106 is pumped into the system 100, the reaction occurs at the reaction zone 108. As the reaction progresses further, the volume of the fuel mixture 104 decreases, as shown in FIG. 3b, since the reactant products 114 are continuously pushed away from the reaction zone 108. The elastic membrane 102 shrinks over this varying contour of the fuel mixture 104, providing a continuous contact between the surface of the fuel mixture 104 and the primary LDM 106. The reactant products 114 exit the elastic membrane 102 and pass by the secondary LDM 118, where additional liquid fuel 110 is added to the reactant products 114.
FIGS. 8a-8c show exemplary embodiments of dimensions and patterns of the product guide 120 that can be for different operation conditions of each fuel system 100. FIG. 8a show an example of a product guide 120 structured outside the surface of the solid fuel 104, where the gap between the fuel surface 104 and enclosure 122 act as the product guide 120. According to another aspect of the invention, hydrolysis occurs either on a radial or longitudinal side of the cylindrical fuel 104, where the concurrently-generated products flow through the concentric gap 120 and exit the fuel zone. FIG. 8b shows a straight-channel product guide 120 structured in the compacted body of a fuel mixture 104. Dimensions and geometries of this channel can determine the flow kinetics of products and allow fine-tuning of product 114 disposal. FIG. 8c shows a spiral-channel product guide 120 structured on the body of a fuel mixture 104 in order to mitigate orientation-dependency in the product 114 disposal.
Orientation-dependent consumption at a certain location of a fuel, in particular of solid type SBH fuels, often causes the uncontrolled dismantling of the fuel form factor, resulting in orientation-dependent hydrogen generation even at a constant pumping rate of a liquid reactant. This typically occurs when there is a slight surplus of a liquid reactant or the reactant is not contained properly at the desired reaction zone of a system. The surplus of leaking reactant is typically pooled at the bottom of the fuel by gravity. This pooled reactant starts unwanted SBH hydrolysis at a location away from the reaction zone, resulting in the uncontrolled fuel consumption. The current invention operates without orientation-dependent consumption, for example the combined embodiment shown in FIGS. 4a-4b and FIG. 8c. 
The present invention has now been described in accordance with several exemplary embodiments, which are intended to be illustrative in all aspects, rather than restrictive. Thus, the present invention is capable of many variations in detailed implementation, which may be derived from the description contained herein by a person of ordinary skill in the art. All such variations are considered to be within the scope and spirit of the present invention as defined by the following claims and their legal equivalents.

## Claims

1. A method of producing hydrogen gas comprising:
(a) delivering a primary liquid delivery medium (LDM) comprising a liquid fuel reactant to contact a solid fuel mixture in a reaction zone under conditions sufficient to cause a reaction between the liquid fuel reactant and the solid fuel mixture;
the delivery of the primary liquid delivery medium being controlled by a movable boundary interface (MBI) that biases the primary liquid delivery medium against the solid fuel mixture;
the reaction zone comprising a reaction product path, said reaction product path being disposed to remove reaction products from said reaction zone during the course of the reaction; and,
(b) independently contacting the reaction products with a second liquid delivery medium outside of the reaction zone.

2. The method of claim 1, said method being conducted in a reaction control mechanism comprising:
a. the solid fuel mixture;
b. the liquid fuel reactant;
c. the primary liquid delivery medium (LDM) fluidly connected to and configured to deliver the liquid fuel reactant to the solid fuel mixture;
d. the movable boundary interface (MBI) coupled to a primary liquid delivery medium distal the solid fuel mixture that biases the primary liquid delivery medium against the solid fuel mixture;
e. the reaction zone defined between the solid fuel mixture and the primary liquid delivery mechanism; and,
f. the second liquid delivery medium located in a reaction product path exiting the reaction zone.

3. The method of claim 1, wherein the reaction product path is comprises at least one channel defined in a surface of said solid fuel mixture, at least one channel disposed through said solid fuel mixture, at least one helix channel disposed about said solid fuel mixture, at least one conduit abutting said solid fuel mixture, or a combination thereof.

4. The method of claim 1, wherein the reaction product path comprises guides disposed in said reaction product path, wherein said guides are disposed to provide said liquid fuel reactant to said reaction zone, wherein the secondary LDM is disposed to provide said liquid fuel reactant independently from said primary LDM.

5. The method of claim 1, wherein the solid fuel mixture and the liquid fuel reactant react through a hydrolysis reaction.

6. The method of claim 1, wherein the solid fuel mixture comprises at least solid sodium borohydride (SBH).

7. The method of claim 1, wherein the MBI moves according to a physical moving element providing a force by an elastic membrane.

8. The method of claim 7, wherein the elastic membrane envelopes said solid fuel mixture.

9. The method of claim 7, wherein the elastic membrane comprises an elastic polymer of fabric, a heat shrinkable fabric, a spring sheet, or a combination thereof.

10. The method of claim 1, wherein the primary LDM is a stationary LDM.

11. The method of claim 1, wherein the primary LDM receives a compression force from said MBI.

12. The method of claim 1, wherein the primary LDM provides liquid to the reaction product path, said reaction production path being disposed between a surface of the solid fuel mixture and the MBI, wherein the reaction product path fluidly passes the reaction products away from the reaction zone.

13. The method of claim 12, wherein the reaction product path comprises at least one channel disposed on a surface of said solid fuel mixture, at least one channel disposed through said solid fuel mixture, at least one helix channel disposed about said solid fuel mixture, a contained region disposed about said solid fuel mixture, at least one conduit abutting said solid fuel mixture, or a combination thereof.

14. The method of claim 1, wherein the MBI is an elastic membrane disposed to envelope said solid fuel mixture, such that when the reactants are present in said reaction product path the elastic membrane is disposed to apply a pressure on the reactants to propagate said reactant along the reaction product path.

15. The method of claim 1, wherein the elastic membrane pressure applied to the reactants is a variable pressure.

16. The method of claim 2, further comprising a pump fluidly connected to the primary LDM.

17. The method of claim 1, wherein the reaction product(s) exiting said reaction zone comprises a combination of a partially reacted liquid fuel reactant and solid fuel mixture.

18. The method of claim 1, wherein the delivery of the primary liquid delivery medium comprising a liquid fuel reactant so as to contact a solid fuel mixture controls the rate and amount of the hydrogen gas produced.

19. The method of claim 1, said method being conducted in a reaction control mechanism comprising:
a. the solid fuel mixture;
b. the liquid fuel reactant contained within a reservoir;
c. the primary liquid delivery medium (LDM) fluidly connecting the reservoir to the solid fuel mixture;
d. the movable boundary interface (MBI) that biases a primary liquid delivery medium against the solid fuel mixture;
e. the reaction zone defined between the solid fuel mixture and the primary liquid delivery mechanism; and
f. the secondary LDM fluidly connecting the reservoir to the reaction product path to control an overall reaction stoichiometry, the secondary LDM being located in the reaction product path exiting the reaction zone.

20. The method of claim 1, said method being conducted in a reaction control mechanism comprising:
the solid fuel mixture;
the liquid fuel reactant that reacts with the solid fuel mixture to produce reaction products;
the primary liquid delivery medium fluidly connecting the liquid fuel reactant to the solid fuel mixture;
the movable boundary interface coupled to the primary liquid delivery medium distal the solid fuel mixture that biases the primary liquid delivery medium against the solid reagent;
the reaction product path, defined in the solid fuel mixture, that fluidly connects the reaction zone defined between the solid fuel mixture and the primary liquid delivery medium with area external the reaction control mechanism; and
the secondary liquid delivery medium fluidly connecting the liquid fuel reactant to the reaction product path.