Method and apparatus for producing hydrogen

Abstract

Methods and apparatus for producing hydrogen. A method for producing hydrogen is provided, the method comprising: electrolyzing water in an electrolytic cell to produce hydrogen and oxygen, the electrolytic cell having a first outlet for the hydrogen; passing the hydrogen from the first outlet of the electrolytic cell to a reaction chamber, the reaction chamber comprising a first inlet for receiving the hydrogen from the electrolytic cell and a second outlet for passing the hydrogen out of the reaction chamber, the reaction chamber containing one or more pieces of metal or alloy thereof at least partially immersed in an alkaline solution, wherein the first inlet is arranged to allow the hydrogen to bubble through the alkaline solution; passing the hydrogen from the second outlet to a gas purification chamber, the gas purification chamber comprising a second inlet for receiving the hydrogen from the reaction chamber and a third outlet for passing the hydrogen out of the purification chamber, the gas purification chamber containing an aqueous solution, wherein the second inlet is arranged to allow the hydrogen to bubble through the aqueous solution; and recovering the hydrogen from the third outlet.

Description

[0001] The present disclosure relates to methods and apparatus for producing hydrogen. In particular, the present disclosure provides a source of suitable clean and pure hydrogen for use in a range of applications including mobile energy generation systems.

[0002] Concerns about fuel depletion have spurred research over the past decade into new methods for generating energy. Hydrogen, which can be environmentally friendly and sustainable, has attracted significant attention from researchers due to its promising applications. Water electrolysis, particularly when combined with renewable electricity (from wind, photovoltaic, tidal, etc.), could provide a "zero-emission" source of hydrogen.

[0003] It is desirable to use hydrogen to generate energy because it has a high calorific value (about 2.5 times that of gasoline). Its combustion in the presence of pure oxygen is completely clean, with the formation of water. Hydrogen also has the ability to be produced in situ or on demand, depending on local energy needs.

[0004] Conventionally, hydrogen is produced by methanol steam reforming, which requires high temperatures and pressures. In addition, the resulting H2 gas is often contaminated with CO, which poisons the fuel cell catalyst and causes it to degrade rapidly during operation.

[0005] Conventional water electrolysis is a well-established commercial technology for ultrapure hydrogen production. Technologies for generating electricity from renewable energy sources (wind, photovoltaic, tidal, etc.) have been extensively developed, but current electricity production does not scale well with energy demand over time. Consequently, efforts are focused on using electricity to produce hydrogen under mild conditions, outside of peak electricity demand times.

[0006] However, conventional electrolysis has several limitations for the large-scale production of H₂. First, it involves expensive electrical energy consumption. Second, any cross-effects that contaminate the produced O₂ with H₂ put the process at risk of implosion. Furthermore, the large amount of chemical reagents used increases development costs.

[0007] To reduce energy consumption, several strategies have been investigated. The first strategy is to reduce ohmic losses. Lower ohmic losses allow the electrolysis system to operate at higher current densities with higher hydrogen production efficiency and purity.

[0008] The second strategy is to develop electrolyte catalysts with high activity and stability. The standard potential for water electrolysis is 1.23V, which means that water decomposition is a strong energy-absorbing reaction (uphill reaction). Although a large number of excellent electrocatalysts for hydrogen evolution reaction or oxygen evolution reaction have been reported, water electrolysis cells still require 1.6V to 2.0V to operate. This is mainly because the anodic oxygen evolution reaction process of water electrolysis is kinetically slow and requires an increased overpotential to drive.

[0009] “Production of hydrogen in the reaction between aluminium and water in the presence of NaOH and KOH”, Porciúncula et al., Braz. J. Chem. Eng., Vol. 29, No. 2, Sao Paulo, April / June 2012, discloses the production of hydrogen from the reaction of aluminium and water.

[0010] “Aluminium and aluminium alloys as sources of hydrogen for fuel cell applications”, Soler et al., Journal of Power Sources 169 (2007) 144-149 discloses the production of hydrogen from aluminium and aluminium alloys with alkaline aqueous solutions.

[0011] CN2249251 discloses an electrolytic cell comprising a hydrogen-oxygen separation membrane made of a nylon-polyester blend fabric.

[0012] It would therefore be desirable to provide improved methods and apparatus for producing hydrogen that would, therefore, and / or address at least some of the problems associated with the prior art, or at least provide a commercially viable alternative thereto.

[0013] In a first aspect, there is provided a method for producing hydrogen, the method comprising:

[0014] electrolyzing water in an electrolytic cell to produce hydrogen and oxygen, the electrolytic cell having a first outlet for the hydrogen;

[0015] passing hydrogen gas from a first outlet of the electrolytic cell to a reaction chamber, the reaction chamber comprising a first inlet for receiving the hydrogen gas from the electrolytic cell and a second outlet for passing the hydrogen gas out of the reaction chamber, the reaction chamber containing one or more pieces of metal or alloy thereof at least partially immersed in an alkaline solution, wherein the first inlet is arranged to allow the hydrogen gas to bubble through the alkaline solution;

[0016] passing the hydrogen gas from the second outlet to a gas cleaning chamber comprising a second inlet for receiving the hydrogen gas from the reaction chamber and a third outlet for passing the hydrogen gas out of the cleaning chamber, the gas cleaning chamber containing an aqueous solution, wherein the second inlet is arranged to bubble the hydrogen gas through the aqueous solution; and

[0017] The hydrogen gas from the third outlet is recovered.

[0018] The present invention will now be further described. In the following paragraphs, different aspects of the present invention are defined in more detail. Unless explicitly indicated otherwise, the various aspects defined in this manner may be combined with any other aspect or aspects. In particular, any feature indicated as preferred or advantageous may be combined with any other feature or features indicated as preferred or advantageous.

[0019] The present invention provides for the electrolytic production of hydrogen in a manner supplemented by chemical production of hydrogen from metals such as aluminum. This "chemically assisted" hydrogen production produces useful value-added by-products such as aluminum hydroxide.

[0020] The method is for producing hydrogen. The method comprises a first step of electrolyzing water in an electrolytic cell to produce hydrogen and oxygen. The electrolysis of water is a well-known technique and involves applying an electric potential through an aqueous solution. While a preferred design is described herein, any standard electrolysis equipment may be used.

[0021] Preferred electrolytic cells have an anode on one side and a cathode on the other, with an ionic solution between them. Electrolytic cells rely on the ionic solution, which is an aqueous solution containing an electrolyte, to improve the solution's conductivity. Increased conductivity of the solution increases the rate at which the electrolysis reaction can proceed, thereby increasing the decomposition of water components and increasing the rate of hydrogen production per unit time. Preferably, the conductivity of the ionic solution in the electrolytic cell is at least 0.25 S / cm, more preferably at least 0.5 S / cm, and most preferably between 0.5 S / cm and 1 S / cm. The conductivity of the ionic solution can be measured using conventional equipment and should be measured at 20°C.

[0022] The preferred ionic solution used in the electrolysis cell is an alkaline solution, such as KOH or NaOH. The concentration of such a solution is preferably at least 0.1 M, preferably at least 0.2 M, and most preferably about 0.3 M. As described below, the ionic solution can be recovered from a later stage of the process.

[0023] According to one embodiment, the ionic solution can be supplemented with aluminum hydroxide or another soluble metal hydroxide (in addition to an alkali such as KOH or NaOH). The amount of metal hydroxide added is preferably present in an amount of at least 0.0001M, for example 0.001M to 0.01M. This has a number of key advantages. Firstly, it improves the electrolysis reaction because it has a strong driving force to react with oxygen and other impurities. This means that the addition seizes some water impurities and slightly increases the purity of the H2 produced. It can also provide a small increase in process temperature. In addition, metal hydroxide is readily available as a by-product of the entire process; for example, aluminum hydroxide can be used in the case where aluminum is used as the metal in the reaction chamber discussed below. The metal hydroxide can therefore be recovered from the reaction chamber. For example, a 0.001M aluminum hydroxide solution can be obtained by dissolving 1g of AlOH in 20L of KOH solution.

[0024] A plurality of neutral plates are typically placed in the ionic solution in the electrolytic cell. These neutral plates are preferably parallel to each other and to the electrodes, and are equally spaced. These neutral plates serve to divide the voltage experienced by the ionic solution into smaller steps, like a series of individual sub-cells, thereby reducing corrosive wear on the electrodes. Hydrogen is produced at the cathode, and oxygen is produced at the anode. Furthermore, in each "sub-cell," hydrogen is produced on the cathode side of the neutral plates, and oxygen is produced on the anode side.

[0025] As oxygen and hydrogen are produced, they bubble up from the ionic solution as gases. The electrolytic cell has a device / means for collecting hydrogen from the cathode side of each "sub-cell" and for collecting oxygen from the anode side of each "sub-cell." Preferably, a membrane is provided between the anode and cathode to prevent cross-contamination of hydrogen and oxygen. In the case where neutral plates are included in the electrolytic cell, separate membranes will be provided between each neutral plate, between the anode and the adjacent neutral plate, and between the cathode and the adjacent neutral plate.

[0026] The present inventors have found that the use of such a membrane improves the safety and productivity of the system. In addition, no expensive type of membrane is required and the membrane can be a mesh membrane. Such a mesh membrane can be easily selected to be impermeable to gaseous oxygen and hydrogen species without hindering the flow of liquid electrolyte. This is particularly the case where the gas rapidly bubbles away from the electrode surface. The mesh membrane is preferably a polymer mesh membrane and can be selected based on the ionic solution used for chemical compatibility. Nylon mesh is preferably used in the case where KOH (aqueous solution) is the ionic solution, and polyester mesh is preferably used in the case where NaOH (aqueous solution) is the ionic solution.

[0027] The preferred nylon monofilament mesh has a cross-number of 300 to 500 per inch. The mesh forms a thin wall that allows water to pass through but not bubbles. H and O ions can pass through the water, pass through the membrane, and form gas on the electrode plate (positive or negative) to which it is attached. Hydrogen stays on the cathode side of the membrane wall, and oxygen stays on the anode side. The mesh is the dividing wall; it forms / separates the two chambers. The gas rises to the top of each side of the chamber and collects at the top.

[0028] The electrolytic cell has a first outlet for hydrogen. This outlet is used to transfer hydrogen collected from the electrolytic cell for subsequent processing. If critical levels of oxygen enter the system and create a risk of implosion, the outlet can be routed to a flash-back inhibitor to prevent damage to the electrolytic cell. However, when using a membrane as described above, oxygen contamination of the hydrogen is reduced or avoided, resulting in a lower risk of implosion.

[0029] The method includes the further step of passing hydrogen gas from a first outlet of the electrolytic cell to a reaction chamber. The reaction chamber includes a first inlet for receiving hydrogen gas from the electrolytic cell and a second outlet for passing hydrogen gas out of the reaction chamber.

[0030] The reaction chamber contains one or more pieces of metal or its alloy at least partially immersed in an alkaline solution. The metal or alloy (which comprises a metal) reacts with the base to produce hydrogen and a metal oxide or hydroxide. The selected metal or alloy should be used in combination with a sufficient concentration of base to allow such a reaction to proceed. The metal or alloy preferably comprises aluminum or steel.

[0031] For aluminum, which is preferred in the present invention, a strong alkaline solution is required because this metal has a very thin Al2O3 passivation layer on its surface that prevents direct attack by water molecules.

[0032] The alkali is not consumed in the reaction and is used as a catalyst, so it can be fully recovered. This is because the aluminate produced in the hydrogen generation undergoes a decomposition reaction that regenerates the alkali. The reaction of aluminum with potassium hydroxide in aqueous solution to produce hydrogen is as follows:

[0033] 2Al+6H2O+2KOH→2K[Al(OH)4]+3H2

[0034] K[Al(OH)4]→KOH+Al(OH)3

[0035] The reaction between aluminum and water follows the following stoichiometry. Therefore, only aluminum and water are consumed to produce hydrogen:

[0036] 2Al+6H2O→2Al(OH)3+3H2

[0037] If necessary, the K[Al(OH)4] product can also be treated with an acid (e.g., sulfuric acid) to recover aluminum hydroxide.

[0038] The form of the metal or alloy is not particularly important. However, the present invention provides a useful opportunity for recycling waste or scrap metal resources (such as aluminum cans). In addition, it is desirable that the metal has a high surface area so that the reaction can proceed at a reasonable rate. Therefore, it is preferred that the metal is processed to have a high surface to weight ratio. In the case of scrap aluminum (such as cans), these can be crushed or broken into fragments. The metal or metal alloy is preferably provided as a plurality of blocks, each weighing less than 0.1 kg.

[0039] The alkaline solution is preferably KOH or NaOH, and preferably has a concentration of at least 1M, for example, 1M to 5M.

[0040] The first inlet is arranged to allow hydrogen to bubble through the alkaline solution. That is, the first inlet is immersed below the liquid surface of the alkaline solution. The hydrogen can preferably enter the alkaline solution through a single point or through a showerhead nozzle for distributing bubbles.

[0041] The present inventors have found that this is very important because stirring the metal / base system increases the reaction rate and hydrogen production. As will be appreciated, in combination with a fuel cell, stirring of the reaction chamber is provided without the need for additional complex equipment (e.g., agitators) or additional energy input. Without wishing to be bound by theory, it is understood that stirring enhances the reaction because stirring thoroughly mixes the solution and creates more surface area for the reaction. Therefore, stirring creates a higher probability for the aluminum-water reaction to occur and makes both hydrogen production and energy efficiency a more efficient process.

[0042] The gas exiting the second outlet is hydrogen obtained by the fuel cell, supplemented by hydrogen produced in the reaction chamber due to the alkali reaction with the metal. This means that the hydrogen production yield can be increased compared to conventional fuel cells. The reaction chamber is a component that can be replaced when the system is used up, thus serving as a supplementary, battery-like source of hydrogen. In addition, the alkali-reactive metal in the form of oxides or hydroxides can be a useful product.

[0043] Aluminum is particularly preferred as the metal (alloys of aluminum may also be used). There are several advantages to using aluminum. Its byproduct, Al(OH) 3, can be used as a useful byproduct in the production of other aluminum salts, including the use of electrolytic recovery of aluminum metal. The aluminum used in the reaction can be obtained from recyclable materials (such as soft drink cans or beer cans). In addition, it reacts with readily and cheaply available alkaline sources (such as KOH and NaOH). The hydrogen produced by the above reaction is pure and suitable for high-purity applications.

[0044] Preferably, the method further comprises recovering the metal oxide or metal hydroxide from the reaction chamber. Preferably, the method further comprises treating the metal oxide or metal hydroxide to recover the metal. Aluminum can be regenerated from aluminum hydroxide by two processes developed in the late 19th century: the Bayer process for producing pure aluminum oxide from bauxite and the Hall-Heroult process for producing aluminum from aluminum oxide.

[0045] The method includes the further step of passing the hydrogen gas from the second outlet of the reaction chamber to a gas purification chamber. The hydrogen gas leaving the reaction chamber may have entrained some ionic solution and / or some alkaline solution as vapor. These are undesirable contaminants in the system that reduce the utilization efficiency of the generated hydrogen gas. The gas purification chamber is used to remove such vapors.

[0046] The gas purification chamber includes a second inlet for receiving hydrogen gas from the reaction chamber and a third outlet for passing the hydrogen gas out of the purification chamber.

[0047] The gas cleaning chamber contains an aqueous solution. This is typically just water. However, vaporized ionic solution and / or alkaline solution entrained with hydrogen will be trapped in the water over time. In cases where the system uses the same reagent (e.g., KOH) to provide the ionic solution in the electrolytic cell and the alkaline solution in the reaction chamber, the water will become a dilute solution of this reagent. Once the level reaches a sufficiently high concentration, the water can be exchanged. Preferably, the method also includes recycling the wastewater solution from the gas cleaning chamber to the electrolytic cell for use as at least a portion of the ionic solution. That is, the contaminated water can be used to make fresh ionic solution for the electrolytic cell to recirculate the reagent (e.g., KOH).

[0048] The second inlet is arranged so that hydrogen gas bubbles through the aqueous solution. That is, the first inlet is immersed below the liquid surface of the aqueous solution. The hydrogen gas can preferably enter the aqueous solution through a single point or through a showerhead nozzle for distributing bubbles and enhancing purification.

[0049] The method allows the recovery of hydrogen from the third outlet. This third outlet represents the product stream from the process. From the gas cleaning chamber, a hydrogen stream at 1 to 5 bar is obtained, ready to be used as a new energy source for various applications, including fuel cells, pyrolysis, heating, cooking, welding, cutting, polishing, and engine decarburization.

[0050] Preferably, the method further comprises recovering oxygen from the electrolytic cell. This can be a useful commercial product. Alternatively, it can be released into the atmosphere.

[0051] According to another aspect, there is provided an apparatus for producing hydrogen, the apparatus comprising:

[0052] an electrolysis cell for electrolyzing water to produce hydrogen and oxygen, the electrolysis cell having a first outlet for hydrogen;

[0053] a reaction chamber comprising a second outlet and a first inlet in fluid communication with the first outlet; and

[0054] a gas cleaning chamber comprising a second inlet in fluid communication with the second outlet and a third outlet for the produced hydrogen gas,

[0055] wherein the reaction chamber comprises one or more pieces of metal or alloy thereof at least partially immersed in an alkaline solution, and wherein the first inlet is for bubbling hydrogen gas through the alkaline solution;

[0056] wherein the gas purge chamber comprises an aqueous solution, and wherein the second inlet is for bubbling hydrogen gas through the aqueous solution.

[0057] All elements as described in the first aspect are equally applicable and understandable in this other aspect, and vice versa.

[0058] Preferably, the electrolytic cell also includes a magnetron for treating water within the electrolytic cell. Treating the electrolyte with the magnetron allows the water to be at its natural frequency, thereby allowing the hydrolysis cell to add less electricity to break down the water molecules. This reduces the overpotential required for the electrolytic cell.

[0059] Preferably, the electrolytic cell comprises a cathode and an anode and a plurality of neutral plates disposed therebetween, each neutral plate being separated from each adjacent neutral plate by a volume containing an electrolytic solution, wherein the volume comprises a mesh membrane defining a cathode-side volume and an anode-side volume, wherein each cathode-side volume is in fluid communication with the first outlet, and wherein the mesh membrane is substantially impermeable to gaseous oxygen and hydrogen. Preferably, the mesh membrane is a mesh membrane, preferably a nylon mesh membrane.

[0060] A mesh membrane can significantly reduce costs and greatly enhance the stability of chemically assisted hydrogen electrocatalytic reactions. The mesh membrane forms a thin wall that allows water to pass but not bubbles. Oxygen bubbles form at the anode, and hydronium ions pass through the water, passing through the membrane and forming hydrogen gas at the cathode. Hydrogen gas resides on the cathode side of the membrane wall, while oxygen resides on the anode side. The mesh membrane forms a dividing wall that separates the two chambers. Gases rise to the top of each side of the chamber, where they gather and exit through their respective outlets.

[0061] Preferably, the apparatus further comprises a flashback arrestor disposed between and in fluid communication with the first outlet and the first inlet.

[0062] Preferably, the apparatus comprises a plurality of interchangeable reaction chambers. These can be removed and replaced when used up. Thus, the continuous production of hydrogen from the fuel cell can be coupled with the batch reaction of the metal.

[0063] Preferably, the apparatus further comprises a first sensor in communication with the first inlet and a second sensor in communication with the second outlet, wherein the first sensor and the second sensor are used to determine the flow rate of hydrogen. This allows an operator to determine when the metal has fully reacted.

[0064] According to yet another aspect, there is provided an apparatus for producing hydrogen, the apparatus comprising a reaction chamber having a second outlet; and

[0065] a gas cleaning chamber comprising a second inlet in fluid communication with the second outlet and a third outlet for produced hydrogen gas,

[0066] wherein the reaction chamber comprises one or more pieces of metal or its alloy at least partially immersed in an alkaline solution;

[0067] wherein the gas purge chamber comprises an aqueous solution, and wherein the second inlet is for bubbling hydrogen gas through the aqueous solution.

[0068] The apparatus of this aspect relates to a reaction chamber as described above, which is coupled to a gas purification system to avoid entrainment of alkaline solution in the hydrogen product.

[0069] According to another aspect, there is provided a vehicle diesel or gasoline engine comprising the apparatus as described above, wherein the third outlet is arranged to supply hydrogen to a combustion chamber of the engine. That is, a vehicle diesel or gasoline engine provided with the apparatus of the first aspect or the other aspect relates to an apparatus comprising a reaction chamber including the second outlet; and

[0070] a gas cleaning chamber comprising a second inlet in fluid communication with the second outlet and a third outlet for the produced hydrogen gas,

[0071] wherein the reaction chamber contains a metal or alloy at least partially immersed in an alkaline solution;

[0072] wherein the gas purge chamber comprises an aqueous solution, and wherein the second inlet is for bubbling hydrogen gas through the aqueous solution.

[0073] In both embodiments, the apparatus provides a source of hydrogen for supplementing the combustion of the fuel. This is particularly advantageous because the vigorous combustion of hydrogen means reduced particulate matter emissions from the engine and reduced fuel use. Preferably, the engine includes a system for monitoring engine performance and controlling hydrogen use.

[0074] In embodiments where only a reaction chamber is provided and no electrolysis cell is involved, the agitation required to promote hydrogen production can be advantageously achieved by the movement and vibration of the vehicle comprising the engine and reaction chamber. Advantageously, the reaction chamber can be swapped out to provide a fresh source of hydrogen fuel, and waste metals (e.g., aluminum hydroxide) can be recovered for use in further processes.

[0075] According to another aspect, there is provided a generator comprising a fuel cell, preferably a vehicle generator, comprising an apparatus as described herein, wherein the third outlet is arranged to supply hydrogen to the fuel cell.

[0076] The method and apparatus described herein have several advantages that are more significant than conventional water electrolysis. First, there are lower energy costs or "near zero" energy costs if renewable energy sources are used. Second, higher value-added products can be obtained from the reaction chamber, which is particularly advantageous where the metals used are recycled metals from solid waste cycles. Third, the method can provide increased safety by preventing O2 from contaminating the desired pure H2, thereby eliminating the danger of possible implosion. Fourth, it has low cost because it can rely on lower cost custom nylon monofilament mesh membranes with hundreds of cross-counts just for the increased purity of H2. The method produces highly pure hydrogen, oxygen and aluminum hydroxide.

[0077] According to another aspect, a cooking device is provided comprising the apparatus according to one of the above aspects and a burner head, wherein the third outlet is arranged to supply hydrogen to the burner head.The burner head may for example be a cooking ring for a conventional gas stove.

[0078] According to another aspect, there is provided a welding device or plasma cutting device comprising the apparatus according to one of the above aspects and a gas torch, wherein the third outlet is arranged to supply hydrogen to the gas torch.The gas torch may take the form of a conventional oxyacetylene torch or a single gas torch.

[0079] According to another aspect, a heating boiler is provided comprising the apparatus according to one of the above aspects and a combustion chamber comprising a pilot flame, wherein the third outlet is arranged to supply hydrogen to the combustion chamber of the boiler. Suitable boiler designs are known.

[0080] According to another aspect, there is provided a Stirling engine comprising an apparatus according to one of the above aspects and a heat engine, wherein the third outlet is arranged to supply hydrogen to the heat engine. The heat engine uses a burner head, and the Stirling engine operates by cyclic compression and expansion of air or other gas (working fluid) at different temperatures, so that there is a net conversion of thermal energy into mechanical work.

[0081] The present invention will now be described with reference to the following non-limiting drawings, in which:

[0082] Figure 1 An electrolytic cell as described herein is shown.

[0083] Figure 2 An apparatus as described herein is shown.

[0084] Figure 1 There is shown an electrolytic cell 1. The cell 1 comprises a tank 5 for containing an ionic aqueous fluid 10 (eg KOH). The system preferably uses purified water and a 1 M KOH standard solution of 30% electrolyte to achieve the necessary conductivity for optimal performance.

[0085] The cell 1 is provided with an anode 20 and a cathode 25 at each end of a tank 5. The cathode 25 and anode 20 are connected to an external circuit (not shown) that provides the driving force for electrolysis.

[0086] The tank 5 is divided by a neutral plate 30. This allows the formation of two sub-cells. The neutral plate may have holes to allow the electrolyte to circulate, or the electrolyte may be piped between the sides of the neutral plate 30.

[0087] The cell 5 is further divided by a nylon mesh membrane 35 located between the neutral plate 30 and each of the anode 20 and cathode 25. This divides each of the two sub-cells so that they have a cathode side volume 40A and an anode side portion 40B.

[0088] A magnetron 46 is provided to energise the fluid 10 in the tank 5. This reduces the electrical potential that needs to be applied by the external circuit.

[0089] The tank 5 is provided with a plurality of gas outlets (45, 50). The hydrogen outlet 45 is provided to communicate with the cathode side volume 40A of each sub-cell. The oxygen outlet 50 is provided to communicate with the anode side volume 40B of each sub-cell.

[0090] In use, a voltage is applied between the cathode 25 and the anode 20. This causes the ionic fluid 10 to decompose. Oxygen bubbles 55 are formed in the anode-side volume 40B of each sub-cell at the anode 20 and on the neutral plate 30. Hydrogen bubbles 60 are formed in the cathode-side volume 40A of each sub-cell at the cathode 25 and on the neutral plate 30. The produced oxygen can be stored as output for various industrial applications or simply released into the atmosphere.

[0091] The preferred circuit involves a Pulse Wave Modular operating at 12V / 24V and 0A to 140A. Like a standard water electrolysis cell, an external circuit power supply provides the potential to drive these reactions, but the power input is much smaller.

[0092] Hydrogen bubbles 60 are collected at the hydrogen outlet 45. Oxygen bubbles 55 are collected at the oxygen outlet 50. The use of a membrane 35 as described herein also serves to prevent O2 contamination in the produced H2, thus avoiding possible explosions.

[0093] Although a single neutral plate 30 is shown, a plurality of neutral plates 30 will typically be employed.

[0094] Figure 2There is shown an apparatus 100 incorporating the above-described electrolytic cell 1. The above numbers have been reused where appropriate.

[0095] The apparatus 100 takes hydrogen from a hydrogen outlet 45. It passes through a flashback arrestor 105, past a check valve 110 and into a reaction chamber 115.

[0096] The reaction chamber 115 is in the form of a bubbler. That is, the hydrogen inlet 120 in the reaction chamber 115 is arranged to introduce hydrogen towards the bottom of the reaction chamber 115. The reaction chamber 115 contains a 1M KOH solution 125 and fragments of scrap aluminum 130.

[0097] In use, hydrogen is bubbled through the KOH solution 125, which is stirred relative to the scrap aluminum waste 130. This promotes the reaction and further production of hydrogen.

[0098] The hydrogen gas exiting the reaction vessel through outlet 135 includes gas from the electrolytic cell and additional hydrogen gas from reaction chamber 115 .

[0099] The hydrogen gas that has left the reaction vessel through outlet 135 passes to inlet 140 of a gas purge chamber 145. The gas purge chamber 145 contains water 150. The water 150 serves to capture any KOH solution 125 that was entrained earlier in the apparatus.

[0100] The purified hydrogen gas leaves the gas purification chamber 145 for use through outlet 155 and control valve 160. The apparatus may be coupled to a hydrogen storage device (not shown) to allow hydrogen to be used at a controlled rate.

[0101] A detailed description of the structure of a suitable electrolytic cell is now provided. The layers are arranged in the order shown across the cell as follows (similar terms describe the same components):

[0102] 1. Acrylic plate 150 mm x 150 mm and 10 mm thick, the plate has connections for positive electrode, negative electrode, water inlet, hydrogen and oxygen outlet

[0103] 2. Positive plate (stainless steel (Inox) 316 110mm×110mm and 1.5mm thickness)

[0104] 3. Oxygen separator (gasket connected to oxygen outlet)

[0105] 4. Membrane (as described in this article)

[0106] 5. General padding

[0107] 6. Hydrogen separator (gasket connected to hydrogen outlet)

[0108] 7. Neutral plate (stainless steel 316)

[0109] 8. Oxygen separator

[0110] 9. Reticular membrane

[0111] 10. General padding

[0112] 11. Hydrogen separator

[0113] 12. Neutral board

[0114] 13. Oxygen separator

[0115] 14. Reticular membrane

[0116] 15. General padding

[0117] 16. Hydrogen separator

[0118] 17. Neutral board

[0119] 18.Oxygen separator

[0120] 19. Reticular membrane

[0121] 20. General padding

[0122] 21. Hydrogen separator

[0123] 22. Neutral board

[0124] 23. Oxygen separator

[0125] 24. Reticular membrane

[0126] 25. General padding

[0127] 26. Hydrogen separator

[0128] 27. Negative plate

[0129] 28. Hydrogen separator

[0130] 29. Acrylic sheet 150mm×150mm and 10mm thickness

[0131] Unless otherwise indicated, all percentages herein are by weight and all pressures are absolute, not gauge.

[0132] Although preferred embodiments of the present invention have been described in detail herein, those skilled in the art will appreciate that changes may be made thereto without departing from the scope of the invention or the appended claims.

Claims

1. A method for producing hydrogen, comprising: electrolyzing water in an electrolytic cell to produce hydrogen and oxygen, the electrolytic cell having a first outlet for the hydrogen; passing the hydrogen gas from the first outlet of the electrolytic cell to a reaction chamber, the reaction chamber comprising a first inlet for receiving the hydrogen gas from the electrolytic cell and a second outlet for passing the hydrogen gas out of the reaction chamber, the reaction chamber comprising one or more pieces of metal or alloy thereof at least partially immersed in an alkaline solution, wherein the first inlet is arranged to allow the hydrogen gas to bubble through the alkaline solution, wherein the first inlet is immersed below the surface of the alkaline solution, and wherein the metal or alloy thereof comprises aluminum; passing the hydrogen gas from the second outlet to a gas cleaning chamber comprising a second inlet for receiving hydrogen gas from the reaction chamber and a third outlet for passing hydrogen gas out of the cleaning chamber, the gas cleaning chamber containing an aqueous solution, wherein the second inlet is arranged to allow the hydrogen gas to be bubbled through the aqueous solution; and The hydrogen gas from the third outlet is recovered.

2. The method of claim 1 , wherein the electrolytic cell comprises an ionic solution having a conductivity of at least 0.25 S / cm.

3. The method of claim 2, wherein the ionic solution comprises an aqueous solution of KOH having a concentration of at least 0.3 M.

4. A method according to claim 2 or claim 3, wherein the ionic solution comprises aluminium hydroxide or a metal hydroxide recovered from the reaction chamber at a concentration of at least 0.0001 M.

5. The method of any one of claims 1 to 3, wherein the method further comprises recovering oxygen from the electrolytic cell.

6. The method according to any one of claims 1 to 3, wherein the metal or alloy thereof is scrap metal.

7. The method according to any one of claims 1 to 3, wherein the reaction chamber comprises a plurality of pieces of metal or its alloy, each piece weighing less than 0.1 kg.

8. The method according to any one of claims 1 to 3, wherein the alkaline solution comprises NaOH or KOH.

9. The method of any one of claims 1 to 3, wherein the method further comprises recovering the metal oxide or metal hydroxide from the reaction chamber.

10. The method of claim 9, wherein the method further comprises treating the metal oxide or metal hydroxide to recover the metal.

11. The method of any one of claims 1 to 3, wherein the method further comprises recycling the wastewater solution from the gas cleaning chamber to the electrolytic cell.

12. An apparatus for producing hydrogen, comprising: an electrolysis cell for electrolyzing water to produce hydrogen and oxygen, the electrolysis cell having a first outlet for hydrogen; a reaction chamber comprising a second outlet and a first inlet in fluid communication with the first outlet; and a gas cleaning chamber comprising a second inlet in fluid communication with said second outlet and a third outlet for produced hydrogen gas, wherein the reaction chamber comprises one or more pieces of metal or its alloy at least partially immersed in an alkaline solution, and wherein the first inlet is for bubbling hydrogen gas through the alkaline solution, wherein the first inlet is immersed below the surface of the alkaline solution, wherein the metal or its alloy comprises aluminum; wherein the gas purge chamber comprises an aqueous solution, and wherein the second inlet is for bubbling hydrogen gas through the aqueous solution.

13. The apparatus of claim 12, wherein the electrolytic cell further comprises a magnetron for treating water within the electrolytic cell.

14. The apparatus of claim 12 , wherein the electrolytic cell comprises a cathode and an anode and a plurality of neutral plates disposed therebetween, each neutral plate being separated from each adjacent neutral plate by a volume for containing an electrolytic solution, wherein the volume comprises a mesh membrane defining a cathode-side volume and an anode-side volume, wherein each cathode-side volume is in fluid communication with the first outlet, and wherein the mesh membrane is impermeable to gaseous oxygen and hydrogen.

15. The apparatus of claim 14, wherein the mesh membrane is a nylon mesh membrane.

16. The apparatus of claim 12, further comprising a flashback arrestor disposed between and in fluid communication with the first outlet and the first inlet.

17. The apparatus of claim 12, wherein the apparatus comprises a plurality of interchangeable reaction chambers.

18. The apparatus of claim 17, further comprising a first sensor in communication with the first inlet and a second sensor in communication with the second outlet, wherein the first sensor and the second sensor are used to determine hydrogen flow.

19. Apparatus according to any one of claims 12 to 18, wherein the apparatus is used in a method according to any one of claims 1 to 11.

20. A vehicular diesel or gasoline engine comprising an apparatus according to any one of claims 12 to 19, wherein the third outlet is arranged to supply hydrogen to a combustion chamber of the engine.

21. A generator comprising a fuel cell, the generator comprising the apparatus according to any one of claims 12 to 19, wherein the third outlet is arranged to supply hydrogen to the fuel cell.

22. The generator of claim 21, wherein the generator is a vehicle generator.

23. A cooking appliance comprising an apparatus according to any one of claims 12 to 19 and a burner head, wherein the third outlet is arranged to supply hydrogen to the burner head.

24. Welding apparatus or plasma cutting apparatus comprising an apparatus according to any one of claims 12 to 19 and a gas torch, wherein the third outlet is arranged to supply hydrogen to the gas torch.

25. A heating boiler comprising an apparatus according to any one of claims 12 to 19 and a combustion chamber comprising a pilot flame, wherein the third outlet is arranged to supply hydrogen to the combustion chamber of the boiler.

26. A Stirling engine comprising an apparatus according to any one of claims 12 to 19 and a heat engine, wherein the third outlet is arranged to supply hydrogen to the heat engine.

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