Device for hydrogen production

Abstract

The invention provides a hydrogen production device for producing hydrogen gas from ammonia, comprising: an outer chamber comprising an outer chamber wall, one or more inner chambers disposed at least partially within the outer chamber, each of the one or more inner chambers comprising a first inner chamber wall and a second inner chamber wall defining an inner subchamber having an inner subchamber internal volume, each second inner chamber wall comprising one or more fins extending therefrom into the inner subchamber, each inner subchamber comprising ammonia decomposition catalyst and having one or more ammonia gas inlets and one or more raw cracked gas outlets, wherein each of the one or more inner chambers has an internal surface area defined as the inner subchamber internal volume facing surface of the second inner chamber wall and the inner subchamber internal volume facing surface of each of the one or more fins; wherein the ratio of the internal surface area in mm2 to the inner subchamber internal volume in mm3 is between approximately 1:2 and 1:6. Also provided are systems comprising said device.

Description

[0001] 2026.01 .14 Specification as filed - POOO8O6WO

[0002] DEVICE FOR HYDROGEN PRODUCTION

[0003] Background

[0004] Hydrogen gas is a promising clean fuel with a significant role to play as part of the global effort to reduce climate change. It can be readily combusted, as well as being used to generate electrical energy using specialized devices such as fuel cells.

[0005] There are a number of methods of generating hydrogen, for example steam reformation of natural gas or water electrolysis. However, one promising method of generating clean hydrogen is the catalytic breakdown (commonly referred to as ‘catalytic cracking’ or simply ‘cracking’) of ammonia gas into hydrogen and nitrogen according to the following reaction:

[0006] 2NH3^ N2+ 3H2

[0007] Devices for producing hydrogen by this means are commonly referred to as ‘ammonia crackers’ and involve providing a heated chamber containing catalyst through which ammonia gas flows. Upon contact with the catalyst, the ammonia is cracked and the hydrogen and nitrogen gas are produced. Such devices are known in the art (see, for example, W02009098452A2).

[0008] The basic premise is to pass heated ammonia gas over an ammonia decomposition catalyst at the correct temperature range to catalytically convert the ammonia into hydrogen and nitrogen. The output gas is typically a mixture of hydrogen, nitrogen, and a residual amount of uncracked ammonia due to the cracking reaction being an equilibrium between ammonia and cracked gas. Further filtration steps are required to purify the hydrogen (i.e. the use of a gas separator such as a palladium filter or a pressure-swing-adsorption device) if the desired output is to be free of Nitrogen or Ammonia.

[0009] In order to optimize the reaction conditions in the reaction chamber of such a device, the incoming gas flow rate, pressure and residency within the reactor must be carefully managed to maximise the decomposition of ammonia as efficiently as possible without compromising the longevity of the device. In addition, good heat transfer is required to minimize the volume of the reactor and to maximise the utilization of the catalyst. For large volume applications, conventional designs of ammonia crackers (see e.g. US4704267A) tend to pass a series of tubes through a2026.01 .14 Specification as filed - POOO8O6WO

[0010] furnace in order to heat the catalyst and reaction gases to temperatures suitable for the ammonia to decompose into nitrogen and hydrogen.

[0011] Applicants have discovered a reaction chamber architecture which addresses the drawbacks of the prior art devices to optimize the decomposition of ammonia into nitrogen and hydrogen.

[0012] Summary of the Invention

[0013] The present invention provides, in a first aspect, a hydrogen production device for producing hydrogen gas from ammonia, comprising: an outer chamber comprising an outer chamber wall, one or more inner chambers disposed at least partially within the outer chamber, each of the one or more inner chambers comprising a first inner chamber wall and a second inner chamber wall defining an inner subchamber having an inner subchamber internal volume, each second inner chamber wall comprising one or more fins extending therefrom into the inner subchamber, each inner subchamber comprising ammonia decomposition catalyst and having one or more ammonia gas inlets and one or more raw cracked gas outlets, wherein the one or more ammonia gas inlets and one or more raw cracked gas outlets are arranged such that the ammonia flows through the inner subchamber internal volume from the one or more ammonia gas inlets to the one or more raw cracked gas outlets and contacts the ammonia decomposition catalyst; wherein each of the one or more inner chambers has an internal surface area defined as the inner subchamber internal volume facing surface of the second inner chamber wall and the inner subchamber internal volume facing surface of each of the one or more fins; wherein the ratio of the internal surface area in mm2to the inner subchamber internal volume in mm3is between approximately 1:2 and 1:6.

[0014] In some embodiments, the first inner chamber wall and the second inner chamber wall each have a tubular shape, wherein the second inner chamber wall is disposed within the first inner chamber wall, defining the inner chamber internal volume therebetween.

[0015] In a further embodiment, the one or more inner chambers comprise a third inner chamber wall, the third inner chamber wall having a tubular shape, wherein the first inner chamber wall and the second inner chamber wall are disposed within the third inner chamber wall, wherein the first inner chamber wall and third inner chamber wall2026.01 .14 Specification as filed - POOO8O6WO

[0016] define an ammonia preheating subchamber parallel to the inner subchamber, the ammonia preheating subchamber having one or more auxiliary ammonia gas inlets, wherein the ammonia preheating subchamber is fluidly connected to the inner subchamber via the one or more ammonia gas inlets, optionally wherein the ammonia preheating subchamber comprises an auxiliary ammonia decomposition catalyst disposed therein.

[0017] In some embodiments, the first inner chamber wall, second inner chamber wall, and / or third inner chamber wall are concentric.

[0018] In some embodiments, the outer chamber comprises one or more baffles disposed in the outer chamber between the outer wall and the one or more inner chambers, optionally wherein the one or more baffles comprises two or more baffles, further optionally wherein the two or more baffles comprise a first subset of baffles and a second subset of baffles, the first subset of baffles having one or more first subset baffle apertures and the second subset of baffles having one or more second subset baffle apertures, wherein the one or more first subset of baffles and the one or more second subset of baffles are disposed through the length of the outer chamber in an alternating sequence.

[0019] In some embodiments, the second inner chamber wall defines a second inner subchamber comprising an internal heat source, optionally an electrical heat source, further optionally wherein the second inner chamber wall comprises a substantially smooth internal face; and / or wherein the second inner chamber wall is a resistive electrical heat source.

[0020] In some embodiments, the outer chamber comprises a flue gas inlet fluidly connected to one or more combustion chambers and a flue gas exhaust, wherein the flue gas inlet and the flue gas exhaust are arranged such that a flue gas flows from the flue gas inlet to the flue gas exhaust via the outer chamber and heats the one or more inner chambers.

[0021] In some embodiments, the one or more fins comprise one or more pluralities of fins, each extending from the second inner chamber wall of at least one of the one or more inner chambers, optionally wherein each of the second inner chamber walls of each of the one or more inner chambers comprises a plurality of fins extending therefrom.2026.01 .14 Specification as filed - POOO8O6WO

[0022] In a further embodiment, at least one of the one or more pluralities of fins is disposed as one or more spirals through the length of the second inner chamber wall; and / or wherein at least one of the one or more pluralities of fins is disposed as one or more rows, each fin of each row being parallel with each fin of the same row on a plane substantially perpendicular to the length of the second inner chamber wall.

[0023] In some embodiments, each of the one or more fins has an angle, wherein at least one of the one or more fins has an angle which is: substantially the same as at least one other of the one or more fins; and / or different to at least one other of the one or more fins; wherein the angle of each fin is chosen from the group consisting of: substantially perpendicular to the length of the second inner chamber wall; substantially parallel with the length of the second inner chamber wall; or angled between substantially perpendicular and substantially parallel with the length of the second inner chamber wall.

[0024] In some embodiments, at least one of the one or more pluralities of fins is disposed as one or more rows, each fin of each row being parallel with each fin of the same row on a plane substantially perpendicular to the length of the second inner chamber wall; optionally comprising a plurality of rows with a distance (d) between each pair of adjacent rows, wherein the distance (d) is the same through the length of the second inner chamber wall; and / or comprising a plurality of rows each with a distance(d) between each pair of adjacent rows, wherein the distance (d) differs between at least two pairs of adjacent rows through the length of the second inner chamber wall.

[0025] In some embodiments, each of the one or more first subset baffle apertures and / or one or more second subset baffle apertures comprises one or more subset baffle aperture proximal edges, wherein each subset baffle aperture proximal edge is equidistant along its length to the closest inner chamber of the one or more inner chambers to the subset baffle aperture proximal edge.

[0026] In some embodiments, the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more ammonia gas inlets are disposed at the opposite end of the outer chamber to the combustion heater, or the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the2026.01 .14 Specification as filed - POOO8O6WO

[0027] one or more ammonia gas inlets are disposed at the same end of the outer chamber to the combustion heater.

[0028] In some embodiments, the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets is disposed at the opposite end of the outer chamber to the combustion heater, wherein the one or more ammonia gas inlets are proximal to the combustion heater relative to the one or more auxiliary ammonia gas inlets, or the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets is disposed at the same end of the outer chamber to the combustion heater, wherein the one or more ammonia gas inlets are distal to the combustion heater relative to the one or more auxiliary ammonia gas inlets; or the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets and the one or more ammonia gas inlets are disposed at the opposite end of the outer chamber to the combustion heater; or the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets and the one or more ammonia gas inlets are disposed at the same end of the outer chamber to the combustion heater.

[0029] In some embodiments, the outer chamber has an outer chamber internal volume defined as the volume defined by the outer wall minus the volume occupied by the one or more inner chambers and, optionally, the one or more baffles, wherein the outer chamber has an outer chamber internal surface area defined as the area of the outer chamber internal volume facing surface of the first inner chamber wall or third inner chamber wall of the one or more inner chambers and each surface of the one or more baffles, wherein the ratio of the outer chamber internal surface area in mm2to the outer chamber internal volume in mm3is between (optionally approximately) 1:1 and 1:100.

[0030] In a second aspect, the invention provides a system for producing purified hydrogen comprising one or more devices according to the first aspect of any of its2026.01 .14 Specification as filed - POOO8O6WO

[0031] embodiments, further comprising a gas separator for separating hydrogen gas from other gases in fluid communication with the one or more devices.

[0032] In a third aspect, the invention provides a system for producing electrical energy comprising the system of the second aspect, further comprising a fuel cell.

[0033] Brief Description of the Drawings

[0034] Figure 1 shows a side-on cross-sectional diagram through the length of a portion of an exemplary device according to the invention having a first inner chamber wall and a second inner chamber wall in each inner chamber.

[0035] Figure 2 shows a three-dimensional view of a portion of an exemplary device according to the invention having a first inner chamber wall and a second inner chamber wall in each inner chamber.

[0036] Figure 3 shows a side-on cross-sectional diagram through the length of a portion of an exemplary device according to the invention having a first inner chamber wall, a second inner chamber wall, and a third inner chamber wall in each inner chamber. Figure 4 shows a three-dimensional view of a portion of an exemplary device according to the invention having a first inner chamber wall, a second inner chamber wall, and a third inner chamber wall in each inner chamber.

[0037] Figure 5 shows a side-on cross-sectional diagram through the length of a portion of an exemplary device according to the invention having one or more baffles.

[0038] Figure 6 shows a top-down view of an exemplary baffle having a first subset baffle aperture profile (top panel) and an exemplary baffle having a second subset baffle aperture profile (bottom panel) according to the invention.

[0039] Figure 7 shows a side-on cross-sectional diagram through the length of a portion of an exemplary device according to the invention having one or more baffles comprising a first subset and a second subset of baffles arranged through the length of the device in alternating fashion.

[0040] Figure 8 shows an internal view of a section of an exemplary device according to embodiments of the invention. Figure 8A shows a 3D view. Figure 8B shows a side-on view. Figure 8C shows a top-down view.2026.01 .14 Specification as filed - POOO8O6WO

[0041] Figure 9 shows an internal view an alternative section of an exemplary device according to embodiments of the invention. Figure 9A shows a 3D view. Figure 9B shows a side-on view. Figure 9C shows a top-down view.

[0042] Figure 10 shows exemplary fins according to the invention. Figure 10A shows a side on view of a fin having a planar profile. Figure 10B shows a side on view of a fin having a varied profile. Figure 10C shows a top-down view of a fin having two indents proximal to the second inner chamber wall.

[0043] Figure 11 shows an alternative section of an exemplary device according to embodiments of the invention as a side-on view.

[0044] Figure 12 shows an exemplary hollow fin according to embodiments of the invention. Figure 12A shows a 3D cutaway view. Figure 12B shows a top-down view. Figure 12C shows a side on cut-away view.

[0045] Figure 13 shows an internal, side on view a section of an exemplary device according to embodiments of the invention having non-overlapping fins.

[0046] Figure 14 shows an internal side-on view of two sections of an exemplary device according to embodiments of the invention. Figure 14A shows a device where the rows are all an equal distance apart from their adjacent row. Figure 14B shows a device where the rows are different distances apart to their adjacent row.

[0047] Figure 15 shows a three-dimensional cutaway of an exemplary device according to the invention.

[0048] Figure 16 shows a top down, cutaway view of a cross section of the inner chambers of the device demonstrating exemplary shapes the walls and subchambers of the device can take.

[0049] Figure 17 shows a system comprising a device according to the invention as part of a system including a gas separator and a hydrogen fuel cell.

[0050] Detailed Description

[0051] In a first aspect, the invention provides a hydrogen production device for producing hydrogen gas from ammonia, comprising: an outer chamber comprising an outer chamber wall, one or more inner chambers disposed at least partially within the outer chamber, each of the one or more inner chambers comprising a first inner chamber2026.01 .14 Specification as filed - POOO8O6WO

[0052] wall and a second inner chamber wall defining an inner subchamber having an inner subchamber internal volume, each second inner chamber wall comprising one or more fins extending therefrom into the inner subchamber, each inner subchamber comprising ammonia decomposition catalyst and having one or more ammonia gas inlets and one or more raw cracked gas outlets, wherein the one or more ammonia gas inlets and one or more raw cracked gas outlets are arranged such that, in use, the ammonia flows through the inner subchamber (internal volume) from the one or more ammonia gas inlets to the one or more raw cracked gas outlets and contacts the ammonia decomposition catalyst; wherein each of the one or more inner chambers has an internal surface area defined as the inner subchamber internal volume facing surface of the second inner chamber wall and the inner subchamber internal volume facing surface of each of the one or more fins; wherein the ratio of the internal surface area in mm2to the inner subchamber internal volume in mm3is between (optionally approximately) 1:2 and 1:6.

[0053] US 2003 / 0232224 A1 relates to a process for producing hydrogen from gaseous ammonia and recycling a portion of said hydrogen to heat the reaction. A conventional tubular ammonia cracking apparatus is shown (cf. Figure 3 therein), but there is no disclosure of the advantageous architecture of the present invention. US 4430304 A disclose a catalytic ‘slab’ reformer where pins and fins are shown extending through all inner walls of the device (cf. Figure 4 therein). There is no disclosure in US 4430304 A of the advantageous architecture of the present invention.

[0054] US 2578193 A discloses an apparatus for producing hydrogen from gaseous ammonia, intended for home use. This is a conventional ammonia cracking device and the document discloses none of the advantageous architecture of the present invention.

[0055] US 2023 / 118083 A1 relates to a generic ammonia cracking device. There is no disclosure therein of the advantageous architecture of the present invention.

[0056] US 2004 / 154223 A1 relates to a generic ammonia cracking device. There is no disclosure therein of the advantageous architecture of the present invention.2026.01 .14 Specification as filed - POOO8O6WO

[0057] GB 1 336375 A relates to an old generic reaction chamber architecture. There is no disclosure therein of the advantageous architecture of the present invention.

[0058] CN 111 170273 A relates to a generic ammonia cracking device as part of a ship power system. There is no disclosure therein of the advantageous architecture of the present invention.

[0059] Turning to the present invention, the outer chamber has or comprises an outer chamber wall. The outer chamber is gas tight except for one or more inlets and one or more outlets. The inlet(s) are optionally one or more flue gas inlets and the outlet(s) are optionally one or more flue gas exhausts. The wall of the chamber may be made of any suitable material, typically a metal. The outer chamber wall may have a cylindrical shape, a cuboidal shape, or any other three-dimensional prismatic shape. The outer chamber can take any shape, depending on the specific requirements for its installation and the envisioned use case.

[0060] Inside the outer chamber, there are one or more inner chambers which are disposed at least partially within the outer chamber. In some embodiments, the one or more inner chambers extend through the length of the outer chamber, and have portions outside of the outer chamber defined by the outer wall. Each of the one or more inner chambers comprises a first inner chamber wall and a second inner chamber wall which together define an inner subchamber having an inner subchamber internal volume.

[0061] In one embodiment, the inner subchamber may have an annular shape where the first inner chamber wall and the second inner chamber wall are both tubular in shape, wherein the second inner chamber wall is disposed within the first inner chamber wall. In a further embodiment, the first inner chamber wall and the second inner chamber wall may be concentric. Tubular in this context means having the overall shape of a cylinder or other prismatic shape. A cylindrical shape is particularly advantageous as it will create a uniform distance between the first inner chamber wall and the second inner chamber wall around the circumference of the inner subchamber internal volume. This results in, amongst other technical advantages, a uniform heat distribution through the inner subchamber internal volume. The term ‘inner subchamber’ is used herein to refer to the main ammonia decomposition2026.01 .14 Specification as filed - POOO8O6WO

[0062] reaction chamber of each of the one or more inner chambers. It is the part(s) of the device where most of the ammonia is converted into hydrogen and nitrogen.

[0063] Any of the outer wall, the first inner chamber wall, and the second inner chamber wall can comprise or be constructed of any suitable material, though a metal is preferred in some embodiments. Preferred materials are Austenitic stainless steels or high nickel chromium content superalloys. These materials are resilient at the temperature and pressure at which the decomposition of ammonia into hydrogen and nitrogen gas occurs and have excellent thermal conductivity.

[0064] Each second inner chamber wall comprises one or more fins extending therefrom into the inner subchamber internal volume. These fins may comprise or be constructed of the same material as the second inner chamber wall or a different material to the second inner chamber wall in some embodiments. When the fins comprise a different material to the second inner chamber wall, the advantage is that a material with better thermal conductivity than the material of the second inner chamber wall may be selected to control heat transfer from one portion of the reaction to another. As stated, the one or more fins extend from a second inner chamber wall of the one or more inner chambers. In other words, they can extend from the second inner chamber wall for example where the second inner chamber wall and the one or more fins are a one-piece construction (e.g. die-cast), or they may be attached to the second inner chamber wall.

[0065] In this context, a one-piece construction means that there is no defined material border between the one or more fins and the second inner chamber wall. This has the advantage of excellent heat transfer between the second inner chamber wall and each of the one or more fins, as there will be negligible imperfections in the join between the two structures.

[0066] In some embodiments, the one or more fins are manufactured as a separate entity and attached to the second inner chamber wall. For example, they may be attached as a mechanical interference fit, or using mechanical fasteners like clips, rivets, and the like. In some embodiments, the one or more fins are attached to the second inner chamber wall by a bonding. This means that the one or more fins are manufactured separately and bonded to the second inner chamber wall, for example by welding or brazing. In some embodiments, the one or more fins may extend2026.01 .14 Specification as filed - POOO8O6WO

[0067] through the width of the inner subchamber such that they contact the first inner chamber wall. In some embodiments, the fins may only extend part way through the width of the inner subchamber such that they do not contact the outer wall.

[0068] Each inner subchamber of the one or more inner chambers comprises ammonia decomposition catalyst, which catalyses the conversion of ammonia into a raw cracked gas including nitrogen and hydrogen when the ammonia gas flows into the inner subchamber. Ammonia gas flows from the one or more ammonia gas inlets through the inner subchamber before exiting via the one or more raw cracked gas outlets, contacting the ammonia decomposition catalyst in a sufficient matter to induce decomposition of the ammonia gas. As such, the one or more ammonia gas inlets and the one or more raw cracked gas outlets are arranged such that, in use, ammonia gas flows through the inner subchamber internal volume and contacts or interacts with the ammonia decomposition catalyst. This can be achieved in any number of ways apparent to the skilled person. For example, the one or more ammonia gas inlets may be disposed at a first end of the inner subchamber, with the one or more raw cracked gas outlets disposed at a second end of the inner subchamber the second end being opposite the first end. In such an example, each end means the opposite ends of the inner subchamber lengthwise. The raw cracked gas consists essentially of a mixture of hydrogen gas, nitrogen gas, and ammonia gas. The ammonia gas in the raw cracked gas is the ammonia which did not decompose into nitrogen and hydrogen as it passed through the inner subchamber. Examples of the ammonia decomposition catalyst include supported monometallic catalysts (e.g. Fe, Ru, Cu, Ni, Ir, Co, Mo, Pt and Pd) multimetallic catalysts or alloy catalysts (e.g. Ni-Pt, Ni-Co, Ir-Ni, Co-Mo, Fe-Co, Fe-Mo, Cu-Zn), nitride and carbide catalysts (e.g. Carbides and nitrides of Mo, Fe, Co, Ni, Ti, V, Mn and Cr), and metal amide / imide catalysts (e.g. LiNH2, NaNH2, KNH2), all of which may be used in the present invention. The ammonia decomposition catalyst is between the first inner chamber wall and the second inner chamber wall of each of the one or more inner chambers. The ammonia decomposition catalyst may be deposited directly upon an internal face of the inner subchamber and / or it may be deposited on a suitable substrate which is then placed inside the inner subchamber. In one embodiment, the ammonia decomposition catalyst is coated on an internal surface of the second inner chamber wall and / or a face of the first inner chamber wall facing the inner2026.01 .14 Specification as filed - POOO8O6WO

[0069] subchamber internal volume. To be clear, the internal surface is the surface which faces into the inner subchamber internal volume and may include the entire surface of the one or more fins. It may be the surface of the second inner chamber wall facing into the inner subchamber and the one or more fins and / or the surface of the first inner chamber wall facing into the inner subchamber. In another embodiment, the ammonia decomposition catalyst is provided on a separate substrate which at least partially fills the inner subchamber internal volume. In a further embodiment, the ammonia decomposition catalyst is both coated on the internal surface of the second inner chamber wall (including the surface of the one or more fins) and / or the first inner chamber wall face facing the inner subchamber internal volume, as well as being provided on a separate substrate which at least partially fills the inner subchamber internal volume of at least one of the one or more inner chambers. The one or more ammonia inlets, one or more raw cracked gas outlets, and the ammonia decomposition catalyst are arranged so that, in use, the ammonia gas flows into the one or more ammonia inlets, flows through the device such that the ammonia gas contacts the ammonia decomposition catalyst such that it is converted into the raw cracked gas comprising hydrogen and nitrogen, and the raw cracked gas comprising hydrogen and nitrogen flows out of the one or more raw cracked gas outlets. Where the term ‘ammonia gas’ is recited throughout this specification, this means a gas mixture comprising ammonia in its gaseous form. In other words, it is an ammonia-containing gas. Such a gas may have any other number and / or ratio of other constituents, provided it comprises ammonia in its gaseous form.

[0070] The ammonia decomposition reaction, being an equilibrium, is favoured at lower pressures and higher temperatures; however these conditions are at odds with designing and building efficient and commercially viable ammonia crackers whereby a compromise set of conditions are selected to give sufficient ammonia conversion at the lowest temperatures and pressures that are suitable for the downstream processes. For example, the reaction may be at a temperature of 400 to 950 degrees Celsius and the pressure anywhere from 0.1 to 40 barg. Typically one or more heat sources are provided to heat the device to the optimal temperature for the chosen pressure. For example, the one or more heat sources may be an additional hot gas stream, an electrical induction heater, a radiative heater, a resistive electrical heater, a combustion heater, or any of the above in combination. In order to provide2026.01 .14 Specification as filed - POOO8O6WO

[0071] good heat transfer throughout the inner subchamber internal volume of the one or more inner chambers, the inner subchamber has one or more fins disposed therein between the first inner chamber wall and the second inner chamber wall, as will be described below. Regardless of the arrangement of the one or more heat sources, the one or more fins function to conduct the heat throughout the inner subchamber internal volume of the one or more inner chambers. The one or more heat sources heat the first inner chamber wall, the second inner chamber wall, and the fins, and ultimately heat the ammonia decomposition catalyst and ammonia gas to the required temperature to decompose the ammonia gas flowing through the inner subchamber. Where the ammonia decomposition catalyst is disposed on a separate substrate which at least partially fills the inner subchamber internal volume, the heat is transferred from the first inner chamber wall, the second inner chamber wall, and the one or more fins, to the substrate so that the reaction can proceed.

[0072] Each of the one or more inner chambers has an internal surface area defined as the inner subchamber internal volume facing surface of the second inner chamber wall and the inner subchamber internal volume facing surface of each of the one or more fins. Applicants have found an advantageous relationship between the internal surface area as defined above and the inner subchamber internal volume which provides optimal reaction conditions for the decomposition of ammonia. The ratio of the internal surface area in mm2to the inner subchamber internal volume in mm3is between (optionally approximately) 1:2 and 1:6 in the present device. In an embodiment, the ratio is between 1:2 and 1:6. In an embodiment, the ratio is (optionally approximately) 1 :2, 1 :3, 1 :4, 1 :5 or 1 :6. Such a ratio has the effect of maximizing the heat transfer from a heat source to the catalyst substrate and / or ammonia decomposition catalyst. For the avoidance of doubt, the inner subchamber internal volume may be defined as the (internal) volume defined by the first inner chamber wall and the second inner chamber wall minus the volume occupied by the one or more fins.

[0073] Part of an exemplary device according to the invention is shown in Figure 1, showing the outer chamber 101 having an outer wall 102, partially enclosing the one or more inner chambers 103, three of which are shown in Figure 1. Each of the one or more inner chambers 103 comprises a first inner chamber wall 104 and a second inner chamber wall 105 which together define the inner subchamber 106 having an inner2026.01 .14 Specification as filed - POOO8O6WO

[0074] subchamber internal volume. Each second inner chamber wall comprises one or more (shown as multiple) fins 107 extending from the second inner chamber wall into the inner subchamber internal volume. The ammonia decomposition catalyst, one or more ammonia gas inlets and one or more raw cracked gas outlets are not shown in Figure 1. Also not shown is one or more heat sources which are provided when the device is in use. Figure 2 shows the same device as a three-dimensional view of part of said device 200, showing the outer chamber 201 having an outer wall 202, partially enclosing the one or more inner chambers 203, three of which are shown in Figure 2. Each of the one or more inner chambers 203 comprises a first inner chamber wall 204 and a second inner chamber wall 205 which together define the inner subchamber 206 having an inner subchamber internal volume. The one or more fins are not shown in Figure 2. Gas flow is represented by arrows passing through the inner subchamber internal volume. As stated, Figure 1 and Figure 2 only show a portion of the device. The inner subchamber internal volume can be any reasonable value known to the skilled person, as the device can be lengthened to suit and will enjoy the benefits of the invention provided the surface area to volume ratio previously recited is maintained.

[0075] As shown in Figure 1 and Figure 2 and as mentioned previously, the first inner chamber wall and the second inner chamber wall may each have a tubular shape in some embodiments of the invention. In such embodiments, the second inner chamber wall is disposed within the first inner chamber wall, defining the inner chamber internal volume therebetween. In an embodiment, the one or more inner chambers comprise a third inner chamber wall having a tubular shape, wherein the first inner chamber wall and the second inner chamber wall are disposed within the third inner chamber wall, wherein the first inner chamber wall and third inner chamber wall define an ammonia preheating subchamber parallel to the inner subchamber. The ammonia preheating subchamber has one or more auxiliary ammonia gas inlets and is fluidly connected to the inner subchamber via the one or more ammonia gas inlets. Such an arrangement is shown in Figure 3 and Figure 4 without the inlets and outlets. Figure 3 shows a cutaway through the length of a portion of the device showing the detail of one of the one or more inner chambers. Figure 3 shows the device 300 having a first inner chamber wall 304 and a second inner chamber wall 305 defining the inner subchamber 306 where the ammonia2026.01 .14 Specification as filed - POOO8O6WO

[0076] decomposition catalyst is disposed, with one or more (multiple shown) fins 307 extending from the second inner chamber wall 307 into the inner subchamber internal volume. The first inner chamber wall and second inner chamber wall are disposed within a third tubular wall 308, and an ammonia preheating subchamber 309 is shown proximal to the outer chamber 301. Gas flow is shown as arrows through the internal volumes of the device. Figure 4 shows the same arrangement as a three dimensional view showing three of the one or more inner chambers. The device 400 again has an outer chamber 401 having an outer chamber wall 402, and one or more inner chambers 403 (three are shown) each comprising a first inner chamber wall 404 and a second inner chamber wall 405, and a third inner chamber wall 408, the first inner chamber wall and second inner chamber wall defining the inner subchamber 406 therebetween, and the third inner chamber wall and first inner chamber wall 408 defining the ammonia preheating subchamber 409 therebetween. The fins are not shown in Figure 4.

[0077] In this embodiment, in use, ammonia enters the ammonia preheating subchamber via one or more auxiliary ammonia gas inlets and flows through the ammonia preheating subchamber, being heated by one or more heat sources as it travels. It flows from the ammonia preheating subchamber via the one or more ammonia gas inlets into the inner subchamber as a heated gas, and decomposes into the raw cracked gas as it travels through the inner subchamber and contacts or interacts with the ammonia decomposition catalyst before exiting via the one or more raw cracked gas outlets. The one or more ammonia gas inlets need not be separate entities in such an embodiment, and instead may simply be the aperture(s) separating the ammonia preheating subchamber and the inner subchamber where the ammonia decomposition reaction occurs. This could be a one or more ammonia transfer apertures in the first inner chamber wall allowing the ammonia gas to flow from the ammonia preheating subchamber into the inner subchamber, for example. The ammonia preheating subchamber described in the above embodiments may further include an auxiliary ammonia decomposition catalyst. This may be coated on the ammonia preheating subchamber walls (i.e. the third inner chamber wall and first inner chamber wall facing the internal volume of the ammonia preheating subchamber) and / or disposed within the ammonia preheating subchamber on a substrate. This has the effect of, in use, maximizing available thermal energy use by2026.01 .14 Specification as filed - POOO8O6WO

[0078] the inner chamber for the conversion of ammonia to nitrogen and hydrogen gas. Examples of the auxiliary ammonia decomposition catalyst include supported monometallic catalysts (e.g. Fe, Ru, Cu, Ni, Ir, Co, Mo, Pt and Pd) multimetallic catalysts or alloy catalysts (e.g. Ni-Pt, Ni-Co, Ir-Ni, Co-Mo, Fe-Co, Fe-Mo, Cu-Zn), nitride and carbide catalysts (e.g. Carbides and nitrides of Mo, Fe, Co, Ni, Ti, V, Mn and Cr), and metal amide / imide catalysts (e.g. LiNH2, NaNH2, KNH2), all of which may be used in the present invention. The ammonia decomposition catalyst present in the inner subchamber and in the ammonia preheating subchamber may be the same or different. Every combination of the abovementioned catalysts is envisioned for use as the auxiliary ammonia decomposition catalyst and the ammonia decomposition catalyst.

[0079] In any of the abovementioned embodiments where the first, second, and / or third inner chamber walls are tubular, they may be concentric. This has the advantage of providing a uniform distance between each pair of walls (i.e. the first and second, first and third, and / or second and third inner chamber walls). This will provide optimal heat transfer characteristics through the width (or diameter) of each inner chamber. As stated previously, tubular means the walls may have the general shape of a cylinder. In some embodiments this means each of the first, second and / or third inner chamber walls is a cylinder. This means that the inner subchamber and / or ammonia preheating subchamber are annular in shape.

[0080] Though the inner subchambers have been shown to be annular in Figures 1 to 4, the skilled person will appreciate that other geometries will achieve the effect of the invention with no substantial modification required. Exemplary embodiments of the general shape of the inner subchamber and / or ammonia preheating subchamber are provided below, though the skilled person will appreciate that there are no limitations on the shape of these subchambers other than the recited internal surface area to volume ratios outlined herein to achieve the advantages of the invention.

[0081] In one embodiment, the inner subchamber and / or ammonia preheating subchamber is annular, formed of the first inner chamber wall and second inner chamber wall, or the first inner chamber wall and third inner chamber wall, said walls having a generally cylindrical shape or profile. This is exemplified in Figures 1 to 4. In other words, the cross-sectional shape of the subchambers across the width of the device2026.01 .14 Specification as filed - POOO8O6WO

[0082] is annular. Such a device is shown, for example, in Figures 3 and 4. In all embodiments, the inner chamber will be an enclosed volume comprising the inner subchamber (and, optionally, the ammonia preheating subchamber) except for any inlets or outlets, such as the one or more ammonia gas inlets (or one or more auxiliary ammonia gas inlets where there is an ammonia preheating subchamber) and one or more raw cracked gas outlets. In some embodiments, the first inner chamber wall and second inner chamber wall and, optionally, the third inner chamber wall are (i.e. have the general shape of) concentric cylinders. The advantage of this is that the length between the walls is equal (uniform) and so heat transfer from one wall to another will be even throughout the internal volume of the inner chamber. Likewise, any heat transfer from the outmost wall to the innermost wall will be even. In such embodiments, the heat source may be within the internal volume defined by the second inner chamber wall alone (i.e. a second internal volume or the inside volume defined by the second inner chamber wall), the second inner chamber wall being a cylinder. Such a device is described later.

[0083] Less optimal embodiments of the invention which still enjoy advantages over the devices of the prior art are similar to the device formed of cylinders described above. In such embodiments, the first inner chamber wall, second inner chamber wall and / or third inner chamber wall may be any three-dimensional prismatic shape. For example, any of the first, second, and / or third inner chamber wall may have the shape of a triangular prism, rectangular prism, pentagonal prism, hexagonal prism, or any other prism. Example cross sectional views of devices are shown in Figure 16 without the one or more fins being shown. In such embodiments, the volume between the first inner chamber wall 1603 and the second inner chamber wall 1602 defines the inner subchamber 1605. In some embodiments, the internal volume defined by the second inner chamber wall defines a second inner subchamber 1630 which may comprise heat source for heating the inner subchamber 1605. In some embodiments, this heat source may be described as an internal heat source, and is optionally an electrical heat source as will be described. As the distance between the walls varies in such devices, there will be an associated loss of efficiency due to non-uniform heat transfer from one wall to another. However, such devices will still enjoy advantages associated with the volumes and internal surface area to volume ratio of the invention. Similarly to the abovementioned embodiment, further embodiments2026.01 .14 Specification as filed - POOO8O6WO

[0084] involving any combination of the first, second, and third inner chamber walls having differing cross-sectional shapes are also envisioned. For example, in one embodiment the first inner chamber wall is the shape of a triangular prism and the second inner chamber wall is the shape of a cylinder. In another embodiment, the first inner chamber wall is the shape of a cylinder and the second inner chamber wall is the shape of a triangular prism. In another embodiment, the first inner chamber wall is the shape of a rectangular, pentagonal, hexagonal, or any other prism, and the second inner chamber wall is the shape of a cylinder. In another embodiment, the first inner chamber wall is the shape of a cylinder and the second inner chamber wall is the shape of a rectangular, pentagonal, hexagonal, or any other prism. In another embodiment, the first inner chamber wall is the shape of a prism, and the second inner chamber wall is the shape of a different prism. All combinations of the listed shapes are included, and also include all combinations of these embodiments with a third inner chamber wall having the shape of a rectangular, pentagonal, hexagonal, cylindrical, or any other prism.

[0085] Depending on the space allotted for the device, for example in an engine bay, the outer chamber may be an irregular prismatic shape to fit into the available space. This would be achieved by the outer wall having an irregular prismatic shape.

[0086] Keeping the internal surface area to volume ratio within each of the one or more inner chambers as required by the invention means that such devices maintain the advantages associated with the invention compared to devices which do not have said ratio. For the avoidance of doubt, the outer wall may similarly have the broad shape of a rectangular, pentagonal, hexagonal, cylindrical, or any other prism also, and in combination with any combination of inner chamber shapes as outlined above.

[0087] In a preferred embodiment, the outer chamber is a cylinder having one or more cylindrical inner chambers disposed therein, wherein each inner chamber wall in each inner chamber is also cylindrical and wherein each inner chamber wall within each of the inner chambers (i.e. the first inner chamber wall, second inner chamber wall and, optionally, third inner chamber wall) is concentric with one another. In another preferred embodiment, the outer chamber is a prism with a (optionally substantially) triangular cross-section, wherein each inner chamber wall in each inner chamber is also cylindrical and wherein each inner chamber wall within each2026.01 .14 Specification as filed - POOO8O6WO

[0088] individual inner chamber (i.e. the first inner chamber wall, second inner chamber wall and, optionally, third inner chamber wall) is concentric with one another. For the avoidance of doubt, this does not mean that all of the inner chambers are concentric with one another, it means that for any given inner chamber, the first, second, and optionally third inner chamber wall are concentric for that inner chamber.

[0089] The outer chamber of the device according to the invention may comprise one or more baffles disposed in the outer chamber (internal volume) between the outer wall and the one or more inner chambers.

[0090] The baffles may extend (optionally substantially) perpendicularly to the length of the one or more inner chambers, or they may be parallel to the length of the one or more inner chambers, or they may be any angle therebetween. Figure 5 shows a cutaway down the length of a portion of the device 500 according to the invention having an outer chamber 501 an outer chamber wall 502 showing one of the one or more inner chambers 503 disposed at least partially within the outer chamber 501 , the inner chamber 503 comprising a first inner chamber wall 504, and a second inner chamber wall 505 comprising one or more fins 507 extending therefrom into the inner subchamber internal volume. A third inner chamber wall 508 is shown defining an ammonia preheating subchamber 509, but this is entirely optional. Disposed within the outer chamber (internal volume) between the outer wall 502 and the one or more inner chambers 503 are one or more baffles, (optionally which extends optionally substantially perpendicularly to the length of the one or more inner chambers 503). In some embodiments of the invention, the one or more baffles are two or more baffles, as shown in Figure 5. The function of the baffles is to reduce the velocity of any gas contained within the outer chamber. The baffles may extend from each and any one of the one or more inner chambers. The baffles may be attached to an outer wall of the one or more inner chambers. This attachment will be by means known to the skilled person such as welding, brazing, or mechanical fastening. A gap is generally left between each baffle and the outer wall, as shown. This allows movement of gas between the baffles and prevents the total compartmentalization of gas within the outer chamber (internal volume). In some embodiments, the outer chamber comprises a flue gas inlet fluidly connected to one or more combustion chambers and a flue gas exhaust, wherein the flue gas inlet and flue gas exhaust are arranged such that, in use, a flue gas flows from the flue gas inlet to the flue gas2026.01 .14 Specification as filed - POOO8O6WO

[0091] exhaust via the outer chamber (internal volume) and heats the one or more inner chambers. In such an embodiment, the baffles increase the residency time of the hot flue gas by lengthening the path of travel for the gas flowing through the outer chamber, to ensure maximum thermal transfer to the one or more inner chambers of the device. In such an embodiment, the one or more combustion heaters provide a heat source for the device, namely a hot flue gas.

[0092] In some embodiments of the present invention, the two or more baffles comprise a first subset of baffles and a second subset of baffles, the first subset of baffles having one or more first subset baffle apertures and the second subset of baffles having one or more second subset baffle apertures, wherein the one or more first subset of baffles and the one or more second subset of baffles are disposed through the length of the outer chamber in an alternating sequence. In said embodiments, the first subset of baffles have one or more first subset baffle apertures having a first subset baffle aperture profile, and the second subset of baffles have one or more second subset baffle apertures having a second subset baffle aperture profile, wherein the first subset baffle aperture profile differs from the second subset baffle aperture profile. The term ‘first baffle aperture profile’ means the design (e.g. shape, size, and / or location) of the one or more subset baffle apertures on the baffle. In some embodiments of the present invention, at least one of the one or more baffles may comprise one or more protrusions and / or one or more depressions extending therefrom. This increases the surface area of the baffle surface and thus reduces the velocity of gases flowing over the baffle surface. A simple example is shown in Figure 6, showing the top-down profile of a baffle for a device wherein the outer chamber and inner chambers (five are shown) have a circular cross-sectional profile. A first subset baffle is shown 610a having a first subset baffle aperture profile 611a is shown in the upper panel, and a second subset baffle 610b is shown having a second subset baffle aperture profile 611b is shown in the lower panel. The one or more baffle apertures 611 are shown in black, and it is clear that the shape, size and / or location (i.e. the baffle aperture profile) differs between the first and second baffle shown. Figure 7 shows a cross-section of a portion of the device 700 wherein one or more first subset baffles 710a and one or more second subset baffles 710b are disposed down the through the length of the outer chamber in an alternating sequence (i.e. a first subset baffle next to a second subset baffle). As before, the2026.01 .14 Specification as filed - POOO8O6WO

[0093] outer chamber 701 , outer chamber wall 702, one of the one or more inner chambers 703 having a first inner chamber wall 704, a second inner chamber wall 705 having one or more fins 707 extending therefrom, a third inner chamber wall 708 an inner subchamber 703 and an (optional) ammonia preheating chamber 709 are shown. The flue gas inlet and flue gas exhaust are not shown. The skilled person would understand optimal placement of the flue gas inlet and flue gas exhaust (or outlet). As an example, the flue gas inlet could be at one end of the length of the outer chamber and the flue gas exhaust could be at the opposite end of the length of the outer chamber, with the one or more baffles disposed within the outer chamber (internal volume) therebetween. The purpose of having two (or more) different subset baffles having differing subset baffle aperture profiles is to increase the residency time of the flue gas in use, in order to increase the amount of time it takes to exit the outer chamber via the flue gas exhaust. If each baffle had the same aperture profile, the aperture would effectively create a through path and the gas would flow directly through the apertures rather than taking the extended path created as a result of the differing aperture profiles. Having two or more different subset baffles having differing subset baffle aperture profiles has the technical effect of maximizing heat transfer from the hot flue gas to the one or more inner chambers of the device in use. Combining a device having one or more baffles as described with a device having one or more inner chambers having an ammonia preheating chamber provides an optimal preheating treatment of the ammonia gas before it enters the reaction chamber (the inner subchamber), creating a highly efficient ammonia decomposition device for producing hydrogen gas.

[0094] To further optimize heat transfer, each of the one or more baffle apertures may have one or more baffle aperture proximal edges, wherein each baffle aperture proximal edge is equidistant along its length to the closest inner chamber of the one or more inner chambers of the device to the baffle aperture proximal edge. Any of the baffle apertures may have such a feature, and in a preferred embodiment, all of the baffle apertures have such a feature. This applies to the first subset baffle apertures, the second subset baffle apertures, or any other baffle subset aperture. This has the effect of creating a uniform distance between the baffle aperture through which the flue gas flows in use and the closest of the one or more inner chambers of the device to prevent hotspots and provide even heat transfer from the outer chamber to the2026.01 .14 Specification as filed - POOO8O6WO

[0095] one or more inner chambers. Numerous different designs for each baffle aperture will be readily apparent to the skilled person and are all considered within the scope of this embodiment of the invention. Three example baffle aperture proximal edges are shown in Figure 6, labelled as 612.

[0096] The outer chamber has an outer chamber internal volume which, for the avoidance of doubt, may be defined as the volume defined by the outer wall minus the volume occupied by the one or more inner chambers and, if present, the one or more baffles. The outer chamber has an outer chamber internal surface area defined as the area of the outer chamber internal volume facing surface of the first (or third, if present) inner chamber wall of the one or more inner chambers and each surface of the one or more baffles. In an embodiment, the ratio of the outer chamber internal surface area in mm2to the outer chamber internal volume in mm3is between (optionally approximately) 1:1 and 1:100. In some embodiments, the ratio is between (optionally approximately) 1:1 and 1:20, optionally 1:1 and 1:15, 1:1 and 1:10, 1:1 and 1:5, 1:1 and 1:3. In some embodiments the ratio is (optionally approximately) 1:1, 1:2, 1:3, 1:4, 1:5, 1 :6, 1:7, 1:8, 1:9, or 1 : 10. In these embodiments, such ratios are particularly desirable where the outer chamber of the device is fluidly connected to one or more combustion chambers and the heat source for heating the one or more inner chambers is a hot flue gas. As such the ratio is adjusted to suit the heat source.

[0097] Where the heat source is a hot flue gas flowing through the outer chamber (such as where the outer chamber is fluidly connected to one or more combustion chambers), ratios between 1:1 and 1:10 are preferred. In some embodiments, the ratio is between (optionally approximately) 1:20 and 1:100, optionally 1:20 and 1:90, 1:20 and 1 :80, 1 :30 and 1 :70, 1 :40 and 1 :60. In some embodiments the ratio is (optionally approximately) 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, or 1:100. Devices of the present invention can comprise a heat source being a combustion chamber outside of and fluidly connected to the outer chamber and / or the outer chamber may be or comprise a combustion device inside the outer chamber. In preferred embodiments of the invention the ratio of the internal surface area in mm2to the inner subchamber internal volume in mm3(the “first ratio”) is between (optionally approximately) 1:2 and 1 :6 and the ratio of the outer chamber internal surface area in mm2to the outer chamber internal volume in mm3(the “second ratio”) is between 1:1 and 1:20, 1:1 and 1:15, 1:1 and 1:10, 1:1 and 1:5, or 1 :1 and 1 :3. In a particular embodiment, the2026.01 .14 Specification as filed - POOO8O6WO

[0098] first ratio is between (optionally approximately) 1 :2 and 1 :6 and the second ratio is between (optionally approximately) 1:1 and 1:3, preferably (optionally approximately) 1 :2. In an alternative embodiment, the first ratio is between (optionally approximately) 1:2 and 1:6 and the second ratio is between (optionally approximately) 1:40 and 1:60, preferably (optionally approximately) 1:50.

[0099] The device of the present invention may comprise the second inner chamber wall defining a second inner subchamber disposed within the inner subchamber comprising an internal heat source. This would have the function of heating up each of the one or more inner chambers from the inside to optimize reaction conditions within the inner subchamber for the decomposition of ammonia. The one or more fins being thermally conductive allows for rapid and highly efficient heating of the inner subchamber by the internal heat source. In some embodiments, the internal heat source is an electrical heat source, such as a radiant heater. In such a case, it is particularly advantageous to have the inside facing surface of the second inner chamber wall be (optionally substantially) smooth to prevent hot spots. Alternatively or in addition, the second inner chamber wall is an internal heat source and is a resistive electrical heat source. As such, it would be connected to an electrical supply which would pass a current through the second inner chamber wall in order to cause it to heat up, with the heat then being transferred into the inner chamber. Devices according to the present invention and any of the embodiments given above may combine having an internal heat source as described with having an external heat source in the form of one or more flue gases flowing through the outer chamber in use as described previously. Such flue gases may be generated by one or more combustion heaters which are fluidly connected to the outer chamber via the flue gas inlet described previously.

[0100] The device of the present invention may comprise the one or more fins comprising one or more pluralities of fins, each extending from the second inner chamber wall of at least one of the one or more inner chambers. In other words, each of the one or more inner chambers has a plurality of fins extending from the second inner chamber wall disposed therein into its inner subchamber internal volume. Such a device is shown, for example, in Figure 1 , showing a plurality of fins disposed in each of the one or more inner chambers 103. In an embodiment, at least one of the one or more inner chambers could comprise a single fin extending from the second inner2026.01 .14 Specification as filed - POOO8O6WO

[0101] chamber wall into the inner subchamber internal volume, the fin spiralling or corkscrewing down the length of the second inner chamber wall to assist with heat transfer. As such, the skilled person will envisage that the chamber could have a single fin which runs the length of the inner subchamber and provides a heat transfer surface, a substrate for the ammonia decomposition catalyst, and may influence gas flow. However, having a plurality of fins allows for further customization of the flow paths of the gas passing through the inner subchamber and is thus advantageous. Whilst we will now discuss how a plurality of fins might be arranged in one of the one or more inner chambers 103, it is envisaged that any combination of arrangements might be employed throughout an exemplary device depending on the requirements of the device and its specific installation and use case. For example, each of the one or more inner chambers may have the same placement of the plurality of fins therewithin, or may have a different placement of the plurality of fins to each other or at least one other of the one or more inner chambers.

[0102] In some embodiments of the invention, the one or more fins comprise one or more pluralities of fins, each extending from the second inner chamber wall of at least one of the one or more inner chambers. In a further embodiment, each of the second inner chambers walls of each of the one or more inner chambers comprises a plurality of fins extending therefrom. In some embodiments, at least one of the one or more pluralities of fins is disposed as one or more spirals through the length of the second inner chamber wall; and / or at least one of the one or more pluralities of fins is disposed as one or more rows within the inner subchamber internal volume, each fin of each row being parallel with each fin of the same row on a plane (optionally substantially) perpendicular to the length of the second inner chamber wall.

[0103] Figure 8 shows a small section of such an arrangement of an inner chamber, in 3D without the first (or third) inner chamber wall shown (A), including side on (B) and top down (C) views. In such an arrangement, the fins 807 are not aligned in the horizontal axis, instead they spiral down the second inner chamber wall 805 in the direction of the length of the second inner chamber wall. In some embodiments there could be two or more such spirals of fins, further altering the gas flow characteristics. A spiral arrangement as shown has the advantage of increasing the path length of the gas flows through the reactor as well as attributing some additional turbulence thus increasing the residency of the gas, as it tends to flow in a spiral, following the2026.01 .14 Specification as filed - POOO8O6WO

[0104] fins through the inner subchamber the gas is able to pick up further heat from the external and / or internal heat source(s). In some embodiments, the one or more fins may be arranged as two spirals down the length of the second inner chamber wall, one of which spirals in a clockwise direction and the other in an anticlockwise direction. This arrangement has the advantage of increasing turbulence in the gas flow thus slowing the flow and increasing gas residency time in the inner subchamber. The skilled person will appreciate that in some instances a combination of the two approaches may be taken, by providing one section structured as a single spiral of fins to speed up gas flow in one section of the inner subchamber and providing a further section structured as two spirals, one arranged in a clockwise direction and one in an anticlockwise direction to slow the gas down.

[0105] In some embodiments, at least one of the plurality of fins are disposed on the second inner chamber wall as one or more rows, each fin of each row being parallel with each fin of the same row on a plane (optionally substantially) perpendicular to the length of the second inner chamber wall. Figure 9 shows a small section of such an arrangement of an inner chamber, in 3D without the first (or third) inner chamber wall shown (A), including side on (B) and top down (C) views. As shown, there are three rows of fins 907 disposed on the second inner chamber wall 905, each row being defined by the alignment of the fins of that row along a plane h which is perpendicular to the flow of gas in use (indicated with an arrow). Having such an ordered structure allows for uniform control of gas flow through a section of the inner subchamber.

[0106] In some embodiments, each fin of the plurality of fins has an angle which is the same as each other fin, as shown for example in Figure 9. As shown in Figure 10, the angle a is that angle which is between the plane h which is perpendicular to the flow of gas through the inner subchamber in use and the lowermost face of the fin. (A) shows a fin 1007 disposed on the second inner chamber wall 1005, the fin having a planar (i.e. flat) profile, and (B) shows a fin 1007 disposed on the second inner chamber wall 1005 having a varied profile through its length. Where the fin has a varied profile, the angle a is measured as an average over the length of the fin.

[0107] In some embodiments, at least one fin of the plurality of fins has an angle which is different to at least one other fin. By adjusting the angle of any one fin, the effect it2026.01 .14 Specification as filed - POOO8O6WO

[0108] has on the gas flow path can be adjusted, thus enabling a fine degree of control over the gas flow through the inner subchamber. In some embodiments, the at least one fin of the plurality of fins having a different angle to at least one other fin is in the same row as the at least one other fin. In some embodiments, the plurality of fins are disposed as at least two rows, and the at least one fin of the plurality of fins having a different angle to at least one other fin is in a different row to the at least one other fin. In an exemplary embodiment, each row of fins in the plurality of fins has an angle which is opposing the angle of the fins in its adjacent rows. An example arrangement is shown in Figure 11. In this arrangement, the angle of the fins of the first and third row 1113 orient the face of the fins in one direction, and the angle of the fins of the second row 1114 orientate the fact of the fins in an opposing direction. Such an arrangement increases the gas residency time. Of course, a combination of these two approaches can be taken, such that the angle of any fin can vary with respect to the other fins on its row or on different rows. This customizability of the device allows for optimal engineering of gas flow for any given installation or use case. For example the angle of each fin can be chosen from the group consisting of (optionally substantially) perpendicular to the length of the inner subchamber (i.e. along the plane has defined previously), (optionally substantially) parallel with the length of the chamber (i.e. perpendicular to plane h as defined previously), and / or angled between (optionally substantially) perpendicular or (optionally substantially) parallel with the length of the chamber (in other words, between the two prior angles).

[0109] As mentioned previously and shown in Figure 10, each fin can have a (optionally substantially) planar or a varied profile through its length. Different shaped fins offer a further degree of control of the localized gas flow characteristics and so allow very fine control of gas residency time and velocities. Any combination of fin shapes are envisaged alone or in combination for the purposes of this invention. In some embodiments, at least one of the one or more fins comprises one or more fin apertures, and / or one or more fin protrusions and / or one or more fin depressions on its surface. These variations increase the overall surface area of the fin, increasing the reaction surface when the fin is coated with catalyst, and allowing further fine control of local gas flow. The fins could be etched, engraved, or roughened to create the fin protrusions and / or fin depressions. In some embodiments, each fin may be shaped to provide a flow channel proximal to the second inner chamber wall and / or2026.01 .14 Specification as filed - POOO8O6WO

[0110] the first inner chamber wall. This is achieved by removing a portion of the fin proximal to the proximal wall, thus allowing gas to flow proximal to the proximal wall, the proximal wall being the first or second inner chamber wall closest to the flow channel. Such a shape may be described as a fin with an ‘indent’. An exemplary fin of this embodiment is shown in Figure 10C, with the fin 1007 having two indents 1012 proximal to the second inner chamber wall 1005.

[0111] In some embodiments, at least one fin may be a hollow fin which comprises a fin subchamber defined by one or more fin walls with an internal fin baffle, wherein the one or more fin walls comprise one or more entry fin apertures on a face of the fin, and one or more exit fin apertures on an opposite face of the fin. An exemplary hollow fin 1207 is shown in Figure12, with Figure 12A showing a 3D cutaway of a fin, Figure 12B showing a top-down view, and Figure 12C showing a side-on cutaway view. In this exemplary embodiment, the one or more fin walls 12071 of the fin subchamber define a fin subchamber volume 12072 with the internal fin baffle 12073 therein. Gas flows into the one or more entry apertures 12074, through the subchamber volume 12072 around the internal fin baffle 12073, and then exits via the one or more exit apertures 12075. In some embodiments, the hollow fin extends (optionally substantially) the width of the inner subchamber, such that it is almost in contact either the first inner chamber wall 1204, so that the flow of gas must occur through the fin subchamber volume 12072 of the hollow fin. Such hollow fins provide further control of gas residency time and create a turbulent flow by forcing the gas down a defined path, which is advantageous in the present invention.

[0112] In some embodiments, the device comprises at least one inner chamber having a plurality of rows of fins, wherein at least one row is disposed such that one or more fins of the at least one row are not wholly overlapping with the one or more fins of at least one other row of the plurality of rows through the length of the inner subchamber. Figure 13 shows an exemplary embodiment of such a device. In the shown section, there are three rows of fins 13076 disposed on the second inner chamber wall 1305, but they are not wholly overlapping with each other. As the gas flows through this section, it is forced to go around the fins, as there is no flow path leading directly from the inlet side to the outlet side of the chamber. This provides a further customization of flow paths within the device, thus allowing further fine control of gas velocity and residency in any one section of the inner subchamber. To further2026.01 .14 Specification as filed - POOO8O6WO

[0113] provide turbulent flow, the one or more fins of each row can be set an angle which is (optionally substantially) perpendicular to the one or more fins of an adjacent row, such that the turbulence of gas increased. This is demonstrated in Figure 11 , though it is envisaged that at least one row is disposed such that one or more fins of the at least one row are not wholly overlapping with the one or more finds of at least one other row of the plurality of rows through the length of the inner subchamber in addition to the one or more fins of each row being at an angle (optionally substantially) perpendicular to the one or more fins of an adjacent row. Indeed, each adjacent row may be angled and offset in this way compared to its neighbouring rows.

[0114] In some embodiments, the device comprises at least one inner chamber comprising a plurality of rows with a distance, d, between each pair of adjacent rows, and this distance remains the same through the length of the inner subchamber. In some embodiments, at least one inner chamber comprises a plurality of rows, each with a distance (d) between each pair of adjacent rows, wherein the distance d differs between at least two pairs of adjacent rows through the length of the inner subchamber. Figure 14 shows a section of the second inner chamber wall 1405 with three rows of fins 1407 disposed thereupon, with a distance d calculated as the distance between each row of fins in the gas flow direction which is indicated by an arrow. In Figure 14A, the distance d is the same between each pair of rows. In Figure 14B, the distance d differs between the first pair of rows, and the second pair of rows. Spacing the rows in this way provides further control over the gas velocity and gas residency time in any one section of the inner subchamber. Applicants have found that having a section of the inner subchamber towards the one or more ammonia gas inlets where the rows are closer together (i.e. the distance d is smaller) compared to the downstream section provides an improved device. In any event, having different distances between the rows of fins allows for multiple designs to suit particular functions for the inner chamber(s).

[0115] The skilled person will appreciate that any combination of the abovementioned embodiments for the inner chamber architecture may be combined in any number in order to produce device within the scope of the present invention.2026.01 .14 Specification as filed - POOO8O6WO

[0116] An exemplary device according to the invention comprises an outer chamber having a (optionally substantially) cylindrical shape having an outer chamber internal volume defined by an outer chamber wall, one or more inner chambers disposed at least partially within the outer chamber, each of the one or more inner chambers comprising a tubular first inner chamber wall, a tubular second inner chamber wall, and a tubular third inner chamber wall, wherein the first inner chamber wall and the second inner chamber wall define an inner subchamber having an inner subchamber internal volume, and the third inner chamber wall and the first inner chamber wall define an ammonia preheating subchamber, and the second inner chamber wall defining a second inner subchamber, the inner subchamber being disposed within the ammonia preheating subchamber, the second inner chamber wall comprising a plurality of fins extending therefrom into the inner subchamber internal volume, the inner subchamber comprising ammonia decomposition catalyst and having one or more ammonia gas inlets and one or more raw cracked gas outlets arranged such that, in use, ammonia gas flows through the inner subchamber internal volume from the one or more ammonia gas inlets to the one or more raw cracked gas outlets and contacts the ammonia decomposition catalyst, wherein the ammonia preheating subchamber is parallel to the inner subchamber, a comprises one or more auxiliary ammonia gas inlets (fluidly connected to an ammonia gas supply in use), arranged such that, in use, ammonia gas flows into the ammonia preheating subchamber via the one or more auxiliary ammonia gas inlets and into the inner subchamber via the one or more ammonia gas inlets,

[0117] wherein the one or more auxiliary ammonia gas inlets are disposed at a first end of the third wall lengthwise, and the ammonia gas inlets are disposed at a second end, opposite the first end lengthwise,

[0118] wherein the device further comprises a combustion heater disposed at the second end, fluidly connected to the outer chamber via a flue gas inlet, the outer chamber further comprising a plurality of baffles disposed in the outer chamber internal volume (optionally substantially perpendicular to the length of the length of the one or more inner chambers), the plurality of baffles comprising a first subset of baffles and a second subset of baffles, the first subset of baffles having one or more first subset baffle apertures and the second subset of baffles having one or more second subset baffle apertures, wherein the one or more first subset of baffles and the one2026.01 .14 Specification as filed - POOO8O6WO

[0119] or more second subset of baffles are disposed through the length of the outer chamber in an alternating sequence, the outer chamber further comprise a flue gas exhaust, wherein the flue gas inlet and the flue gas exhaust are arranged such that, in use, a hot flue gas travels from the combustion heater into the outer chamber via the flue gas inlet, through the outer chamber internal volume and out of the outer chamber via the flue gas exhaust,

[0120] wherein the device further comprises an internal heat source, the internal heat source being a radiant heater disposed within the second internal subchamber; wherein each of the inner chambers has an internal surface area defined as the inner subchamber internal volume facing surface of the second inner chamber wall and the inner subchamber internal volume facing surface of each of the one or more fins;

[0121] wherein the ratio of the internal surface area in mm2to the inner subchamber internal volume in mm3is between (optionally approximately) 1:2 and 1:6. It will be understood that any of the features of this exemplary device may be combined with the features described in the prior examples or embodiments of the present invention.

[0122] A three dimension cross section of an exemplary device according to the invention is shown in Figure 15 as a three dimensional cutaway diagram showing the device 1500 having an outer chamber 1501 having an outer chamber internal volume defined by an outer chamber wall 1502, one or more inner chambers 1503 comprising a first inner chamber wall 1504 and a second inner chamber wall 1505 defining an inner subchamber 1506 having an inner subchamber internal volume, each second inner chamber wall 1505 comprising one or more fins (not shown) extending therefrom into the inner subchamber internal volume, each inner subchamber comprising ammonia decomposition catalyst and having one or more ammonia gas inlets and one or more raw cracked gas outlets, wherein the one or more ammonia gas inlets and one or more raw cracked gas outlets are arranged such that, in use, the ammonia flows through the inner subchamber internal volume from the one or more ammonia gas inlets to the one or more raw cracked gas outlets and contacts the ammonia decomposition catalyst. In said device, the outer chamber comprises a plurality of baffles 1510, a flue gas exhaust 1520, and a plurality of flue2026.01 .14 Specification as filed - POOO8O6WO

[0123] gas inlets 1521 , wherein, in use, the flue gas inlet and flue gas exhausts are fluidly connected to a flue gas source such as a combustion chamber, wherein the flue gas inlet and flue gas exhausts are arranged such that, in use, the flow of flue gas through the outer chamber is (optionally substantially perpendicular) to the length of the one or more inner chambers. Also shown is a common pre-chamber 1522 fluidly connected to the one or more ammonia gas inlets and a common post-chamber 1523 fluidly connected to the one or more raw cracked gas outlets. Whilst this architecture demonstrates having the one or more combustion heaters disposed on an axis perpendicular to the length of the one or more inner chambers, other architectures may be advantageous, as described below.

[0124] In some embodiments, the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more ammonia gas inlets are disposed at the opposite end of the outer chamber to the combustion heater. In this embodiment, one end is at or near one terminus of the length one or more inner chambers, and the opposite end is at the opposite terminus. In this embodiment, in use, the ammonia gas flows in the opposite direction to the hot flue gas emitted by the combustion chamber flowing through the outer chamber.

[0125] In a further embodiment, the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more ammonia gas inlets are disposed at the same end of the outer chamber to the combustion heater. In this embodiment, one end is at or near one terminus of the length one or more inner chambers, and the opposite end is at the opposite terminus. In this embodiment, in use, the ammonia gas flows in the same direction to the hot flue gas emitted by the combustion chamber flowing through the outer chamber.

[0126] In a further embodiment, the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets is disposed at the opposite end of the outer chamber to the combustion heater, wherein the one or more ammonia gas inlets are proximal to the combustion heater relative to the one or more auxiliary ammonia gas inlets. In this embodiment, one end is at or near one terminus of the2026.01 .14 Specification as filed - POOO8O6WO

[0127] length one or more inner chambers, and the opposite end is at the opposite terminus. In this embodiment, in use, the ammonia gas first flows through the ammonia preheating subchamber in the opposite direction to the hot flue gas emitted by the combustion heater flowing through the outer chamber, before entering the inner subchamber via the one or more ammonia gas inlets and flowing in the same direction to the hot flue gas.

[0128] In a further embodiment, the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets is disposed at the same end of the outer chamber to the combustion heater, wherein the one or more ammonia gas inlets are distal to the combustion heater relative to the one or more auxiliary ammonia gas inlets In this embodiment, one end is at or near one terminus of the length one or more inner chambers, and the opposite end is at the opposite terminus. In this embodiment, in use, the ammonia gas first flows through the ammonia preheating subchamber in the same direction to the hot flue gas emitted by the combustion heater flowing through the outer chamber, before entering the inner subchamber via the one or more ammonia gas inlets and flowing in the opposite direction to the hot flue gas.

[0129] In a further embodiment, the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets and the one or more ammonia gas inlets are disposed at the opposite end of the outer chamber to the combustion heater. In this embodiment, one end is at or near one terminus of the length one or more inner chambers, and the opposite end is at the opposite terminus. In this embodiment, in use, the ammonia gas first flows through the ammonia preheating subchamber in the same direction to the hot flue gas emitted by the combustion heater flowing through the outer chamber, before entering the inner subchamber via the one or more ammonia gas inlets and flowing in the same direction to the hot flue gas.

[0130] In a further embodiment, the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets and the one or more ammonia gas inlets are disposed at the same end of the outer chamber to the combustion heater. In this2026.01 .14 Specification as filed - POOO8O6WO

[0131] embodiment, one end is at or near one terminus of the length one or more inner chambers. In this embodiment, in use, the ammonia gas first flows through the ammonia preheating subchamber in the opposite direction to the hot flue gas emitted by the combustion heater flowing through the outer chamber, before entering the inner subchamber via the one or more ammonia gas inlets and flowing in the opposite direction to the hot flue gas.

[0132] In a further aspect the invention provides a system for producing purified hydrogen comprising one or more of the devices of the first aspect and any of their embodiments or examples, and further comprises a gas separator for separating hydrogen gas from other gases in fluid communication with the one or more devices. The gas separator may be a pressure swing adsorption device and / or a palladium filter, which are known in the art for separating hydrogen from nitrogen and ammonia, though any suitable gas separation device may be used. For example, see US6340382B1 and GB969673A (incorporated by reference herein).

[0133] In a further aspect the invention provides a system for producing electrical energy comprising the system of the previous aspect, further comprising a fuel cell. Such a system allows the hydrogen produced by the one or more devices of the first aspect to be used to generate electrical energy. Suitable fuel cells are known in the art. For example, see GB2508649A (incorporated by reference herein).

[0134] Figure 17 shows a system having a device according to the present invention 1700 in fluid communication with a gas separator 1715 via a common raw cracked gas flow conduit 1716, The gas separator is in fluid communication with a hydrogen fuel cell 1717 via a common purified cracked gas flow conduit 1718. The flow of gas is indicated with arrows, showing an ammonia gas entering the ammonia cracker 1700 via an inlet, the ammonia gas is decomposed into a raw cracked gas comprising nitrogen gas and hydrogen gas, and the raw cracked gas exits the ammonia cracker into the common raw cracked gas flow conduit 1716 and flows through an inlet into a gas separator 1715 where the nitrogen and any other impurities are removed from the raw cracked gas, producing a purified cracked gas consisting essentially of hydrogen. The purified cracked gas exits the gas separator via an outlet and is conveyed to a hydrogen fuel cell 1717 via the common purified cracked gas flow conduit 1718 where the hydrogen is used along with oxygen gas to generate electricity.2026.01 .14 Specification as filed - P000806WO

[0135] In a further aspect of the invention, the device for producing hydrogen could be a steam reformer rather than a device for producing hydrogen gas from ammonia. For example, the device of the first aspect may be a hydrocarbon steam reformer, or other thermocatalytic decomposition reactor having any of the features and embodiments or examples of the first aspect.

Claims

2026.01 .14 Specification as filed - POOO8O6WOClaims1. A hydrogen production device for producing hydrogen gas from ammonia, comprising:an outer chamber comprising an outer chamber wall,one or more inner chambers disposed at least partially within the outer chamber, each of the one or more inner chambers comprising a first inner chamber wall and a second inner chamber wall defining an inner subchamber having an inner subchamber internal volume, each second inner chamber wall comprising one or more fins extending therefrom into the inner subchamber, each inner subchamber comprising ammonia decomposition catalyst and having one or more ammonia gas inlets and one or more raw cracked gas outlets, wherein the one or more ammonia gas inlets and one or more raw cracked gas outlets are arranged such that the ammonia flows through the inner subchamber internal volume from the one or more ammonia gas inlets to the one or more raw cracked gas outlets and contacts the ammonia decomposition catalyst;wherein each of the one or more inner chambers has an internal surface area defined as the inner subchamber internal volume facing surface of the second inner chamber wall and the inner subchamber internal volume facing surface of each of the one or more fins;wherein the ratio of the internal surface area in mm2to the inner subchamber internal volume in mm3is between approximately 1:2 and 1:6.

2. The device according to claim 1 , wherein the first inner chamber wall and the second inner chamber wall each have a tubular shape, wherein the second inner chamber wall is disposed within the first inner chamber wall, defining the inner chamber internal volume therebetween.

3. The device according to claim 2, wherein the one or more inner chambers comprise a third inner chamber wall, the third inner chamber wall having a tubular shape,wherein the first inner chamber wall and the second inner chamber wall are disposed within the third inner chamber wall,2026.01 .14 Specification as filed - POOO8O6WOwherein the first inner chamber wall and third inner chamber wall define an ammonia preheating subchamber parallel to the inner subchamber, the ammonia preheating subchamber having one or more auxiliary ammonia gas inlets,wherein the ammonia preheating subchamber is fluidly connected to the inner subchamber via the one or more ammonia gas inlets, optionallywherein the ammonia preheating subchamber comprises an auxiliary ammonia decomposition catalyst disposed therein.

4. The device according to claim 2 or claim 3, wherein the first inner chamber wall, second inner chamber wall, and / or third inner chamber wall are concentric.

5. The device according to any preceding claim wherein the outer chamber comprises one or more baffles disposed in the outer chamber between the outer wall and the one or more inner chambers, optionallywherein the one or more baffles comprises two or more baffles, further optionally wherein the two or more baffles comprise a first subset of baffles and a second subset of baffles, the first subset of baffles having one or more first subset baffle apertures and the second subset of baffles having one or more second subset baffle apertures, wherein the one or more first subset of baffles and the one or more second subset of baffles are disposed through the length of the outer chamber in an alternating sequence.

6. The device according to any one of claims 2 to 5, wherein the second inner chamber wall defines a second inner subchamber comprising an internal heat source, optionally an electrical heat source, further optionally wherein the second inner chamber wall comprises a substantially smooth internal face; and / or wherein the second inner chamber wall is a resistive electrical heat source.

7. The device according to any preceding claim, wherein the outer chamber comprises a flue gas inlet fluidly connected to one or more combustion chambers and a flue gas exhaust, wherein the flue gas inlet and the flue gas exhaust are arranged such that a flue gas flows from the flue gas inlet to the flue gas exhaust via the outer chamber and heats the one or more inner chambers.2026.01 .14 Specification as filed - POOO8O6WO8. The device according to any preceding claim, wherein the one or more fins comprise one or more pluralities of fins, each extending from the second inner chamber wall of at least one of the one or more inner chambers, optionally wherein each of the second inner chamber walls of each of the one or more inner chambers comprises a plurality of fins extending therefrom.

9. The device according to claim 8, wherein at least one of the one or more pluralities of fins is disposed as one or more spirals through the length of the second inner chamber wall; and / orwherein at least one of the one or more pluralities of fins is disposed as one or more rows, each fin of each row being parallel with each fin of the same row on a plane substantially perpendicular to the length of the second inner chamber wall.

10. The device according to claim 8 or claim 9, wherein each of the one or more fins has an angle, wherein at least one of the one or more fins has an angle which is: substantially the same as at least one other of the one or more fins; and / or different to at least one other of the one or more fins;wherein the angle of each fin is chosen from the group consisting of: substantially perpendicular to the length of the second inner chamber wall; substantially parallel with the length of the second inner chamber wall; or angled between substantially perpendicular and substantially parallel with the length of the second inner chamber wall.

11. The device according to any one of claims 8 to 10, wherein at least one of the one or more pluralities of fins is disposed as one or more rows, each fin of each row being parallel with each fin of the same row on a plane substantially perpendicular to the length of the second inner chamber wall; optionally comprising a plurality of rows with a distance (d) between each pair of adjacent rows, wherein the distance (d) is the same through the length of the second inner chamber wall; and / or comprising a plurality of rows each with a distance (d) between each pair of adjacent rows, wherein the distance (d) differs between at least two pairs of adjacent rows through the length of the second inner chamber wall.2026.01 .14 Specification as filed - POOO8O6WO12. The device according to any one of claims 5 to 11 , wherein each of the one or more first subset baffle apertures and / or one or more second subset baffle apertures comprises one or more subset baffle aperture proximal edges, wherein each subset baffle aperture proximal edge is equidistant along its length to the closest inner chamber of the one or more inner chambers to the subset baffle aperture proximal edge.

13. The device according to any one of claims 2 to 12, wherein the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more ammonia gas inlets are disposed at the opposite end of the outer chamber to the combustion heater, or wherein the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more ammonia gas inlets are disposed at the same end of the outer chamber to the combustion heater.

14. The device according to any one claims 3 to 12, wherein the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets is disposed at the opposite end of the outer chamber to the combustion heater, wherein the one or more ammonia gas inlets are proximal to the combustion heater relative to the one or more auxiliary ammonia gas inlets, orwherein the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets is disposed at the same end of the outer chamber to the combustion heater, wherein the one or more ammonia gas inlets are distal to the combustion heater relative to the one or more auxiliary ammonia gas inlets; or wherein the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more auxiliary ammonia gas inlets and the one or more ammonia gas inlets are disposed at the opposite end of the outer chamber to the combustion heater; orwherein the device comprises a combustion heater at one end of the outer chamber along the length of the one or more inner chambers, wherein the one or more2026.01 .14 Specification as filed - POOO8O6WOauxiliary ammonia gas inlets and the one or more ammonia gas inlets are disposed at the same end of the outer chamber to the combustion heater.

15. The device according to any preceding claim, wherein the outer chamber has an outer chamber internal volume defined as the volume defined by the outer wall minus the volume occupied by the one or more inner chambers and, optionally, the one or more baffles, wherein the outer chamber has an outer chamber internal surface area defined as the area of the outer chamber internal volume facing surface of the first inner chamber wall or third inner chamber wall of the one or more inner chambers and each surface of the one or more baffles, wherein the ratio of the outer chamber internal surface area in mm2to the outer chamber internal volume in mm3is between (optionally approximately) 1:1 and 1:100.

16. A system for producing purified hydrogen comprising one or more devices according to any one of claims 1 to 15, further comprising a gas separator for separating hydrogen gas from other gases in fluid communication with the one or more devices.

17. A system for producing electrical energy comprising the system of claim 16, further comprising a fuel cell.

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