Hydrogen production apparatus, hydrogen permeable membrane, and method for manufacturing a hydrogen permeable membrane

Abstract

To improve the technology for separating hydrogen. [Solution] The hydrogen production apparatus 10 comprises a hydrogen permeable membrane 50 that permeates hydrogen, an ammonia decomposition catalyst 51 provided on the primary side of the hydrogen permeable membrane 50 for decomposing ammonia to produce hydrogen and nitrogen, a flow flange 30 that constitutes a raw material gas supply channel for supplying a raw material gas containing ammonia to the primary side surface of the hydrogen permeable membrane 50, and a hydrogen recovery channel 43 for recovering hydrogen that has permeated to the secondary side surface of the hydrogen permeable membrane 50. The hydrogen permeable membrane 50 has a flat plate shape.

Description

Technical Field

[0001] The present disclosure relates to a hydrogen production apparatus, a hydrogen permeable membrane, and a method for manufacturing a hydrogen permeable membrane.

Background Art

[0002] Towards the realization of carbon neutrality, hydrogen is expected as a decarbonized fuel to replace fossil fuels. However, since hydrogen is difficult to store and transport, the use of hydrogen carriers such as ammonia has been considered. If hydrogen can be efficiently extracted from ammonia, the extracted hydrogen can be used for power generation, semiconductor manufacturing, etc.

[0003] In order to extract hydrogen from ammonia, a two-step process is required, which is to decompose ammonia at a high temperature and separate only hydrogen from the resulting mixed gas of hydrogen and nitrogen (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors of the present invention recognized that it is necessary to further improve the technology for producing hydrogen from ammonia to improve efficiency, and came up with the technology of the present disclosure.

[0006] The present disclosure has been made in view of such problems, and the object thereof is to improve the technology for producing hydrogen.

Means for Solving the Problems

[0007] To solve the above problems, a hydrogen production apparatus according to one aspect of the present invention comprises a hydrogen permeable membrane that permeates hydrogen, a catalyst for a chemical reaction that decomposes ammonia to produce hydrogen and nitrogen, provided on the primary side of the hydrogen permeable membrane, a raw material gas supply channel for supplying a raw material gas containing ammonia to the primary side surface of the hydrogen permeable membrane, and a hydrogen recovery channel for recovering hydrogen that has permeated to the secondary side surface of the hydrogen permeable membrane. The hydrogen permeable membrane has a flat plate shape.

[0008] Another aspect of the present invention is also a hydrogen production apparatus. This apparatus comprises a hydrogen permeable membrane that permeates hydrogen, a catalyst for a chemical reaction that decomposes ammonia to produce hydrogen and nitrogen, supported on the primary surface of the hydrogen permeable membrane, a raw material gas supply channel for supplying a raw material gas containing ammonia to the primary surface of the hydrogen permeable membrane, and a hydrogen recovery channel for recovering hydrogen that has permeated to the secondary surface of the hydrogen permeable membrane.

[0009] Yet another aspect of the present invention is a hydrogen permeable membrane. This hydrogen permeable membrane has a catalyst on its surface for a chemical reaction that decomposes ammonia to produce hydrogen and nitrogen.

[0010] A further aspect of the present invention is a method for producing a hydrogen permeable membrane. This method includes the steps of oxidizing both surfaces of a hydrogen permeable membrane and supporting a catalyst for a chemical reaction that decomposes ammonia to produce hydrogen and nitrogen on the primary surface of the hydrogen permeable membrane. [Effects of the Invention]

[0011] According to this disclosure, it is possible to improve the technology for producing hydrogen. [Brief explanation of the drawing]

[0012] [Figure 1] This figure schematically shows the configuration of a hydrogen production apparatus according to the first embodiment of this disclosure. [Figure 2] This diagram schematically shows the upper surface of the flow flange. [Figure 3] This figure schematically shows another example of the configuration of a hydrogen production apparatus according to the first embodiment. [Figure 4] It is a diagram showing the gas flow in the hydrogen production apparatus shown in FIG. 3. [Figure 5] It is a diagram showing the ammonia conversion rate of the hydrogen production apparatuses of Example 1A and Comparative Example 1. [Figure 6] It is a diagram showing the change in ammonia conversion rate with respect to the ammonia supply pressure and the secondary side pressure. [Figure 7] It is a diagram showing the change in ammonia conversion rate with respect to the ammonia supply pressure and the secondary side pressure. [Figure 8] It is a diagram showing the change in hydrogen separation efficiency with respect to the ammonia supply pressure. [Figure 9] It is a diagram showing the change in hydrogen separation efficiency with respect to the ammonia supply pressure. [Figure 10] It is a diagram showing the change in hydrogen production efficiency with respect to the ammonia supply pressure. [Figure 11] It is a diagram showing the change in hydrogen production efficiency with respect to the ammonia supply pressure. [Figure 12] It is a diagram showing the ammonia conversion rate in the hydrogen production apparatuses of Example 1A, Example 1B, and Example 2. [Figure 13] It is a diagram showing the ammonia conversion rate in the hydrogen production apparatuses of Example 1A, Example 1B, and Example 2. [Figure 14] It is a diagram showing the hydrogen separation efficiency in the hydrogen production apparatuses of Example 1A, Example 1B, and Example 2. [Figure 15] It is a diagram showing the hydrogen separation efficiency in the hydrogen production apparatuses of Example 1A, Example 1B, and Example 2. [Figure 16] It is a diagram showing the hydrogen production efficiency in the hydrogen production apparatuses of Example 1A, Example 1B, and Example 2. [Figure 17] It is a diagram showing the hydrogen production efficiency in the hydrogen production apparatuses of Example 1A, Example 1B, and Example 2. [Figure 18] It is a diagram schematically showing the configuration of the catalyst-integrated hydrogen permeable membrane provided in the hydrogen production apparatus of the second embodiment. [Figure 19]It is a diagram schematically showing a method for manufacturing a catalyst-integrated hydrogen permeable membrane according to a second embodiment. [Figure 20] It is a diagram showing the change over time of the hydrogen separation rate and the ammonia conversion rate.

Mode for Carrying Out the Invention

[0013] As an embodiment of the present disclosure, a technique for producing hydrogen from ammonia will be described. The hydrogen production apparatus according to the embodiment of the present disclosure decomposes raw material ammonia into hydrogen and nitrogen, and separates only hydrogen, thereby producing high-purity hydrogen.

[0014] (First Embodiment) FIG. 1 schematically shows the configuration of a hydrogen production apparatus according to a first embodiment of the present disclosure. This figure schematically shows a cross section of the hydrogen production apparatus 10.

[0015] The hydrogen production apparatus 10 includes a primary-side flange 11 and a secondary-side flange 12.

[0016] The primary-side flange 11 includes a primary-side SUS flange 20, a primary-side support 21, a primary-side gasket 22, a primary-side gasket 23, a distribution flange 30, a hydrogen permeable membrane 50, and an ammonia decomposition catalyst 51.

[0017] The secondary-side flange 12 includes a secondary-side SUS flange 40, a secondary-side support 41, a secondary-side gasket 42, and a hydrogen recovery flow path 43.

[0018] In this figure, an example in which the primary-side flange 11 and the secondary-side flange 12 are connected in the vertical direction is shown, but they may be connected in the horizontal direction or in any direction. In the following description, for convenience, the positional relationship is expressed assuming that the primary-side flange 11 and the secondary-side flange 12 are connected in the vertical direction as shown in this figure.

[0019] The hydrogen permeable membrane 50 selectively permeates hydrogen. Of the gases containing ammonia, hydrogen, and nitrogen on the primary side, only hydrogen permeates to the secondary side, thus allowing for the separation of hydrogen only. The hydrogen permeable membrane 50 may be formed from a non-palladium (Pd) metal, such as a metal belonging to Group 5, such as vanadium (V), niobium (Nb), or tantalum (Ta), or an alloy in which a non-Pd metal is the main metal (hereinafter also simply referred to as "non-Pd alloy"). The hydrogen permeable membrane 50 may be formed by oxidizing both surfaces of a film of a non-Pd metal or non-Pd alloy such as vanadium. The hydrogen permeable membrane 50 may be formed by coating both surfaces of a film of a non-Pd metal or non-Pd alloy with a catalyst such as Pd. The hydrogen permeable membrane 50 may be formed from Pd or a Pd alloy.

[0020] The hydrogen permeable membrane 50 is formed in a flat plate shape. This eliminates the need to process the hydrogen permeable membrane 50 into cylindrical or other shapes, thus reducing the manufacturing cost of the hydrogen permeable membrane 50. Furthermore, it improves the strength and durability of the hydrogen permeable membrane 50. In particular, when using a hydrogen permeable membrane 50 containing Group 5 metals, the effect of using a flat plate-shaped hydrogen permeable membrane 50 is significant for the following reasons.

[0021] Conventionally, research and development of Pd-based hydrogen permeable membranes formed from Pd or Pd alloys has been widely conducted. However, because Pd is a rare and expensive metal, and its hydrogen permeability is insufficient, the inventors have been designing and developing hydrogen permeable membranes formed from non-Pd metals or non-Pd alloys such as Group 5 elements as alternative materials.

[0022] Compared to Pd, which has a face-centered cubic (fcc) lattice structure, Group 5 metals such as V, Nb, and Ta, which have a body-centered cubic (bcc) lattice structure, have a lower activation energy for hydrogen diffusion, resulting in a higher hydrogen diffusion coefficient at low temperatures. Therefore, it is believed that high hydrogen permeation rates can be obtained even at relatively low temperatures by using hydrogen permeable membranes formed from these metals or alloys. In particular, V has a low activation energy for hydrogen diffusion and is suitable as a material for hydrogen permeable membranes. Furthermore, these metals and alloys are considerably cheaper than Pd and Pd alloys, making them suitable from the viewpoint of manufacturing costs.

[0023] Group 5 elements such as V and Nb are known to undergo hydrogen embrittlement, a process in which their mechanical properties deteriorate significantly when large amounts of hydrogen are dissolved in them. Specifically, a ductile-brittle transition occurs when the hydrogen concentration exceeds approximately 0.2 (H / M). Therefore, to avoid hydrogen embrittlement fracture of hydrogen permeable membranes, it is necessary to control the dissolved hydrogen concentration to 0.2 (H / M) or less. According to the inventors' findings, the dissolved hydrogen concentration can be suppressed by adding elements with a lower affinity for hydrogen than Group 5 elements, such as Fe, Ni, cobalt (Co), copper (Cu), chromium (Cr), molybdenum (Mo), and tungsten (W), to Group 5 elements. Therefore, by forming a hydrogen permeable membrane with an alloy to which the above elements are added to Group 5 elements, it is possible to avoid hydrogen embrittlement and fracture of the hydrogen permeable membrane during use of the hydrogen production equipment.

[0024] On the other hand, when dissimilar elements are dissolved in a metal, its strength increases due to solid solution strengthening. Furthermore, when the metal is rolled to form a hydrogen permeable film, its strength increases again due to work hardening. This makes it difficult to process the rolled metal film into shapes such as cylinders.

[0025] The hydrogen production apparatus 10 of this disclosure uses a flat hydrogen permeable membrane 50, thereby solving the new problems described above, reducing the manufacturing cost of the hydrogen permeable membrane, and improving the strength and durability of the hydrogen permeable membrane. The hydrogen production apparatus 10 of this disclosure has a configuration and structure suitable for using a flat hydrogen permeable membrane 50, as will be described in detail below.

[0026] The ammonia decomposition catalyst 51 contains a catalyst for a chemical reaction that decomposes ammonia into hydrogen and nitrogen. The ammonia decomposition catalyst 51 may be a metal oxide supported with metals from groups 8 to 10 such as nickel (Ni), platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iron (Fe), and cobalt (Co), as well as alkaline earth metals and lanthanides. The metal oxide is aluminum oxide, cerium oxide, magnesium oxide, niobium oxide, titanium oxide, vanadium oxide, tantalum oxide, hafnium oxide, yttrium oxide, lanthanum oxide, or neodymium oxide, and more preferably aluminum oxide, cerium oxide, magnesium oxide, and titanium oxide. The type, amount, shape, particle size, etc. of the ammonia decomposition catalyst 51 may be selected according to the specifications of the hydrogen production apparatus 10. The specifications of the hydrogen production apparatus 10 may include the operating temperature, operating time, amount of hydrogen to be produced, purity, production efficiency, production rate, and the required durability time of the hydrogen production apparatus 10. The ammonia decomposition catalyst 51 is housed in a containment section formed by the primary gasket 22.

[0027] The primary support 21 supports the ammonia decomposition catalyst 51. The primary support 21 may be a porous filter formed in a disc shape from metal fibers such as stainless steel, a wire mesh, a nonwoven fabric, or the like.

[0028] The primary gasket 22 and primary gasket 23 seal the space between the primary flange 11 and the secondary flange 12. The primary gasket 23 and primary gasket 22 may be formed from a metal such as stainless steel in a cylindrical or hollow disc shape. The primary gasket 23 has the same height as the primary support 21. The primary gasket 22 is provided to cover the periphery of the ammonia decomposition catalyst 51 and forms a housing for containing the ammonia decomposition catalyst 51. The height of the primary gasket 22 may be adjusted according to the amount, shape, particle size, etc., of the ammonia decomposition catalyst 51.

[0029] The flow distribution flange 30 constitutes a raw material gas supply channel for supplying a raw material gas containing ammonia to the primary side of the hydrogen permeable membrane 50. The flow distribution flange 30 includes a straight pipe section 31a and an expanded section 31b at the upper end that is in contact with the primary side support 21. The expanded section 31b is expanded to an inner diameter equivalent to that of the ammonia decomposition catalyst 51 and the hydrogen permeable membrane 50, and distributes the raw material gas evenly throughout the entire ammonia decomposition catalyst 51 and the hydrogen permeable membrane 50. This makes it possible to efficiently utilize the entire ammonia decomposition catalyst 51 and the hydrogen permeable membrane 50 to generate and separate hydrogen.

[0030] Ammonia that did not decompose, nitrogen produced by the decomposition of ammonia, and hydrogen that did not permeate the hydrogen permeable membrane 50 are discharged from the discharge channel 32 between the flow flange 30 and the primary side SUS flange 20.

[0031] The secondary gasket 42 seals the periphery of the hydrogen permeable membrane 50. The secondary gasket 42 may be formed from a metal such as stainless steel in a cylindrical or hollow disc shape.

[0032] The secondary support 41 supports the hydrogen permeable membrane 50 to prevent deformation and rupture on the secondary side. The secondary support 41 may be a porous filter formed from metal fibers such as stainless steel, a wire mesh, a nonwoven fabric, etc. Preferably, the secondary support 41 has elasticity, flexibility, and cushioning properties. This allows it to absorb stress on the hydrogen permeable membrane 50 and more effectively prevent rupture of the hydrogen permeable membrane 50. The secondary support 41 is made of a material that does not generate gas during use of the hydrogen production apparatus 10 and does not chemically react with hydrogen. High-purity hydrogen is present at a high concentration on the secondary side of the hydrogen permeable membrane 50 and is exposed to a strong reducing atmosphere, so it is preferable that the secondary support 41 be made of a material that does not undergo a reduction reaction even in such an environment. Also, since the secondary support 41 may come into direct contact with the hydrogen permeable membrane 50, it is preferable that it be made of a material that does not form an alloy or undergo a chemical reaction with the metal or alloy forming the hydrogen permeable membrane 50. The secondary support 41 may be made of, for example, stainless steel, silicon dioxide, alumina, etc. This prevents the secondary support 41 from undergoing chemical reactions with hydrogen or the hydrogen permeable membrane, thereby avoiding adverse effects on the hydrogen permeation performance of the hydrogen permeable membrane 50 and the purity of the recovered hydrogen. Preferably, the secondary support 41 has a filtration diameter and porosity (porosity, air void ratio, porosity) such that hydrogen that has permeated through the hydrogen permeable membrane 50 can pass through at a sufficient flow rate.

[0033] The hydrogen recovery channel 43 is connected to a configuration for recovering hydrogen that has permeated the hydrogen permeate membrane 50 and reached the hydrogen recovery channel 43.

[0034] In the hydrogen production apparatus 10, when the raw material ammonia gas is supplied from the flow flange 30, the ammonia gas passes through the primary support 21 from the expansion section 31b and comes into contact with the ammonia decomposition catalyst 51. At least a portion of the ammonia gas that comes into contact with the ammonia decomposition catalyst 51 is decomposed into nitrogen and hydrogen. When the generated hydrogen comes into contact with the primary surface of the hydrogen permeate membrane 50, at least a portion of it permeates to the secondary side of the hydrogen permeate membrane 50. The hydrogen that permeates to the secondary side is recovered from the hydrogen recovery channel 43. The permeation of hydrogen in the hydrogen permeate membrane 50 is driven by the difference in hydrogen partial pressure between the primary and secondary sides of the hydrogen permeate membrane 50. Since the hydrogen that permeates to the secondary side is recovered from the hydrogen recovery channel 43, the hydrogen partial pressure on the secondary side is kept low. Therefore, the hydrogen that comes into contact with the primary surface of the hydrogen permeate membrane 50 can be efficiently and quickly permeated to the secondary side. Since the hydrogen generated by the ammonia decomposition reaction by the ammonia decomposition catalyst 51 is rapidly extracted to the secondary side, the ammonia decomposition reaction proceeds without reaching equilibrium. This allows for the efficient and rapid decomposition of ammonia to produce hydrogen.

[0035] Figure 2 schematically shows the upper surface of the flow distribution flange 30. A flow path may be formed in the housing portion on the upper surface of the expanded portion 31b of the flow distribution flange 30, where the ammonia decomposition catalyst 51 is housed, for distributing the raw material gas throughout the ammonia decomposition catalyst 51. The flow path may be formed by baffles 34 for restricting or guiding the gas flow. In the example shown in this figure, a helical baffle 34 is formed, but in other examples, baffles of straight lines, curves, grids, etc., may be formed, or multiple layers of baffles may be stacked. This makes it easier for the raw material gas and the generated hydrogen to flow along the baffle 34, so that the raw material gas containing ammonia can be evenly distributed throughout the ammonia decomposition catalyst 51. In addition, the generated hydrogen can be evenly distributed throughout the hydrogen permeable membrane 50. As a result, hydrogen can be generated and separated using the entire ammonia decomposition catalyst 51 and hydrogen permeable membrane 50.

[0036] The procedure for manufacturing the hydrogen production apparatus 10 shown in Figure 1 will be explained. First, each component is formed. The hydrogen permeable membrane 50 may be formed by rolling the raw material metal or alloy. The primary side SUS flange 20 and the flow flange 30 are assembled with screws or the like. The primary side support 21 is laid on the flow flange 30, and the primary side gasket 23 is laid so as to surround the primary side support 21. The primary side gasket 22 is placed on the primary side gasket 23, and the ammonia decomposition catalyst 51 is filled inside the primary side gasket 22. The hydrogen permeable membrane 50 is placed on the ammonia decomposition catalyst 51, and the secondary side gasket 42 is attached. Finally, the primary side flange 11 and the secondary side flange 12 are assembled.

[0037] According to the hydrogen production apparatus 10 of this embodiment, the reaction processes of ammonia decomposition and hydrogen separation can be integrated, so hydrogen can be produced, separated, and purified directly and efficiently from ammonia. Furthermore, the hydrogen production apparatus 10 of this embodiment has a simple structure in which the ammonia decomposition catalyst 51 and the hydrogen permeable membrane 50 are fixed with bolts and nuts between flanges with a surface seal structure, making it easy to replace deteriorated ammonia decomposition catalyst 51, hydrogen permeable membrane 50, and other consumable parts. Therefore, the operational reliability and maintainability of the hydrogen production apparatus 10 can be improved, and maintenance costs can be reduced.

[0038] Figure 3 schematically shows another example of the configuration of a hydrogen production apparatus according to the embodiment. In the hydrogen production apparatus 10 shown in this figure, a side wall 33 is provided on the flow flange 30. In addition, a primary support 21 and a primary gasket 23 are provided between the ammonia decomposition catalyst 51 and the hydrogen permeable membrane 50. The other configurations, operation, and effects are the same as those of the hydrogen production apparatus 10 shown in Figure 1.

[0039] The side wall 33 is cylindrically provided between the peripheral edge of the flow flange 30 and the peripheral edge of the hydrogen permeable membrane 50. The side wall 33 may be made of a metal such as stainless steel. In the example shown in this figure, the side wall 33 also serves as a housing for the ammonia decomposition catalyst 51.

[0040] The primary support 21 is provided on the side wall 33 and supports the ammonia decomposition catalyst 51 and the hydrogen permeable membrane 50 so as to separate them.

[0041] Figure 4 shows the gas flow in the hydrogen production apparatus shown in Figure 3. The side wall 33 functions as a baffle to restrict or guide the gas flow, and by restricting the flow path between the space containing the ammonia decomposition catalyst 51 and the discharge channel 32 to the small gap between the side wall 33 and the hydrogen permeable membrane 50, it guides the hydrogen produced by the decomposition of ammonia to the vicinity of the hydrogen permeable membrane 50. This prevents the produced hydrogen from being discharged from the discharge channel 32 without passing through the hydrogen permeable membrane 50, thereby improving the hydrogen production efficiency.

[0042] The height of the side wall 33 may be the same as the height of the primary side gasket 22. In this case, the width of the flow path between the space containing the ammonia decomposition catalyst 51 and the discharge flow path 32 is the same as the height of the primary side support 21.

[0043] The procedure for manufacturing the hydrogen production apparatus 10 shown in Figure 3 will be explained. First, each component is formed. The primary side SUS flange 20 and the flow control flange 30 are assembled with screws or the like. The ammonia decomposition catalyst 51 is filled inside the side wall 33 of the flow control flange 30. The primary side gasket 22 is placed on the outside of the side wall 33 of the flow control flange 30, and the primary side support 21 is mounted on the primary side gasket 22, side wall 33, and ammonia decomposition catalyst 51. The hydrogen permeable membrane 50 is placed on the primary side support 21, and the secondary side gasket 42 is mounted. Finally, the primary side flange 11 and the secondary side flange 12 are assembled.

[0044] [Example 1] A bench-scale hydrogen production apparatus was fabricated, and hydrogen was produced using ammonia as a raw material. The hydrogen production apparatus 10 shown in Figure 1 is designated as Example 1A, and the hydrogen production apparatus 10 shown in Figure 3 is designated as Example 1B.

[0045] A hydrogen production apparatus 10 was operated using 4.9 g (6.0 cc) of a Ru-based ammonia decomposition catalyst (a catalyst with ruthenium supported on alumina), with an ammonia supply pressure of 0.3 MPa and an ammonia supply rate of 70 mL per minute, and the ammonia conversion rate was measured. In comparative example 1, a SUS plate was installed instead of the hydrogen permeable membrane 50, and the hydrogen production apparatus 10 was operated without separating hydrogen, and the ammonia conversion rate was measured. Figure 5 shows the ammonia conversion rates of the hydrogen production apparatuses in Example 1A and comparative example 1. It was confirmed that a higher ammonia conversion rate was obtained in the hydrogen production apparatus 10 of Example 1A than when only the catalyst was used. When the secondary side is depressurized, the hydrogen flow rate increases, and the ammonia conversion rate improves further. The hydrogen production efficiency when the secondary side is depressurized at 450°C was 83%, demonstrating that hydrogen can be produced with high efficiency.

[0046] Figures 6 and 7 show the change in ammonia conversion rate with respect to ammonia supply pressure and secondary pressure. In Example 1A (type-A in the figure), 4.9 g (6.0 cc) of Ru-based ammonia decomposition catalyst was used, and the ammonia supply rate was 60 cc per minute. In Example 1B (type-B in the figure), 3.6 g (4.5 cc) of Ru-based ammonia decomposition catalyst was used, and the ammonia supply rate was 45 cc per minute. Figure 6 shows the results when operated at 400°C, and Figure 7 shows the results when operated at 450°C. In both Example 1A and Example 1B, the ammonia conversion rate tends to be higher with higher ammonia supply pressure, lowering the secondary pressure, and higher operating temperatures. In particular, when the ammonia supply pressure was 0.3 MPa and the system was operated at 450°C with a reduced secondary pressure, a high ammonia conversion rate was obtained in both Example 1A and Example 1B.

[0047] Figures 8 and 9 show the change in hydrogen separation efficiency with respect to ammonia supply pressure. The experimental conditions are the same as described above. Figure 8 shows the results when operated at 400°C, and Figure 9 shows the results when operated at 450°C. In both Example 1A and Example 1B, there is a tendency for hydrogen separation efficiency to be higher with higher ammonia supply pressure, lowering the secondary side pressure, and higher operating temperatures. In particular, when the ammonia supply pressure was 0.3 MPa, the system was operated at 450°C, and the secondary side pressure was reduced, high hydrogen separation efficiency was obtained in both Example 1A and Example 1B.

[0048] Figures 10 and 11 show the change in hydrogen production efficiency with respect to ammonia supply pressure. The experimental conditions are the same as described above. Figure 10 shows the results when operated at 400°C, and Figure 11 shows the results when operated at 450°C. In both Example 1A and Example 1B, there is a tendency for hydrogen production efficiency to be higher with higher ammonia supply pressure, lowering the secondary side pressure, and higher operating temperatures. In particular, when the ammonia supply pressure was set to 0.3 MPa, the system was operated at 450°C, and the secondary side pressure was reduced, high hydrogen separation efficiency was obtained in both Example 1A and Example 1B.

[0049] [Example 2] In addition to the hydrogen production apparatus 10 of Examples 1A and 1B, the performance of the hydrogen production apparatus 10 of Example 2, which has the flow path shown in Figure 2, was compared. A Ru-based ammonia decomposition catalyst (a catalyst with ruthenium supported on alumina) was used in amounts of 4.9 g (6.0 cc) in Example 1A, 4.9 g (6.0 cc) in Example 1B, and 4.6 g (5.2 cc) in Example 2. The ammonia supply rate was 60 cc per minute, the secondary side was reduced in pressure, and the apparatus was operated at 400°C and 450°C. The ammonia conversion rate, hydrogen separation efficiency, and hydrogen production efficiency were measured.

[0050] Figures 12 and 13 show the ammonia conversion rates in the hydrogen production apparatus 10 for Example 1A (type: A in the figure), Example 1B (type: B8 in the figure), and Example 2 (type: B8-S in the figure). Figure 12 shows the results when operated at 400°C, and Figure 13 shows the results when operated at 450°C. Figures 14 and 15 show the hydrogen separation efficiency in the hydrogen production apparatus 10 for Example 1A, Example 1B, and Example 2. Figure 14 shows the results when operated at 400°C, and Figure 15 shows the results when operated at 450°C. Figures 16 and 17 show the hydrogen production efficiency in the hydrogen production apparatus 10 for Example 1A, Example 1B, and Example 2. Figure 16 shows the results when operated at 400°C, and Figure 17 shows the results when operated at 450°C. In the hydrogen production apparatus 10 of Example 2, the ammonia conversion rate and hydrogen production efficiency were improved by securing a flow path within the housing of the ammonia decomposition catalyst 51.

[0051] Furthermore, when the hydrogen gas produced by the hydrogen production apparatus 10 in Example 1A was analyzed using a hydrogen, nitrogen, and ammonia analysis system manufactured by GL Sciences, the concentrations of nitrogen and ammonia were below the detection limit.

[0052] (Second Embodiment) The hydrogen production apparatus according to the second embodiment of this disclosure uses a catalyst-integrated hydrogen permeable membrane that integrates the hydrogen permeable membrane 50 and the ammonia decomposition catalyst 51 of the hydrogen production apparatus 10 of the first embodiment. Other configurations, operations, and effects are the same as those of the hydrogen production apparatus 10 of the first embodiment.

[0053] Figure 18 schematically shows the configuration of a catalyst-integrated hydrogen permeable membrane 54 provided in the hydrogen production apparatus 10 of the second embodiment. The catalyst-integrated hydrogen permeable membrane 54 comprises a metal layer 52, oxide layers 53a and 53b, and an ammonia decomposition catalyst 51.

[0054] The metal layer 52 may be formed from a hydrogen-permeable non-palladium metal or an alloy mainly composed of a non-palladium metal. The metal layer 52 may be formed from a pure metal of a group 5 element or an alloy mainly composed of a group 5 element. The metal layer 52 may be formed from Pd or an alloy of Pd, etc.

[0055] The oxide layers 53a and 53b are formed on both surfaces of the metal layer 52. The oxide layers 53a and 53b may also be formed by oxidizing both surfaces of the metal layer 52. In this case, the oxides constituting the oxide layers 53a and 53b are oxides of the metal or alloy constituting the metal layer 52. For example, if the metal layer 52 is made of vanadium, the oxide layers 53a and 53b may be made of V2O5, V2O3, etc. A V film without a catalyst layer does not permeate hydrogen, but it is known that by forming an oxide film mainly composed of V2O3 on both surfaces, hydrogen can permeate at six times the rate of a commercially available Pd film containing 25% Ag by atomic percentage. The oxide layers 53a and 53b may also be formed by growing oxide layers on both surfaces of the metal layer 52 by physical vapor deposition or chemical vapor deposition. In this case, the oxides constituting the oxide layers 53a and 53b may be oxides of the metal or alloy constituting the metal layer 52, or they may be different types of oxides.

[0056] The ammonia decomposition catalyst 51 is supported on an oxide layer 53a formed on the primary surface of the metal layer 52. The ammonia decomposition catalyst 51 may be Ni, a Ni-containing compound, Ru, a Ru-containing compound, a V-containing compound, or the like.

[0057] Figure 19 schematically shows a method for manufacturing a catalyst-integrated hydrogen permeable membrane 54 according to the second embodiment. (1) A film of V is formed. (2) Both surfaces of the V film are heated at 500°C in air to oxidize V, thereby forming oxide layers 53a and 53b composed of V2O5. (3) By heating at 500°C in a hydrogen atmosphere, the V2O5 constituting the oxide layers 53a and 53b is reduced to V2O3. (4) Ni nanoparticles are supported on the oxide layer 53a by arc plasma deposition to form an ammonia decomposition catalyst 51.

[0058] The oxide layers 53a and 53b may be formed from fine particles with a large specific surface area. For example, when forming the oxide layers 53a and 53b with an oxide of V, fine particles of V2O5 with a large specific surface area can be formed by dissolving NH4VO3 and oxalic acid in water, evaporating the mixture to dryness, and then calcining the resulting solution. This can improve the activity of the ammonia decomposition catalyst 51 supported on the oxide layer 53a.

[0059] [Example 3] The catalyst-integrated hydrogen permeable membrane 54, adjusted using the method described above, was installed in the hydrogen production apparatus 10, and an operational test was conducted. Figure 20 shows the changes in hydrogen separation rate and ammonia conversion rate over time. The primary supply pressure was 0.3 MPa, the secondary side was evacuated to a vacuum, and the apparatus was operated at 600°C. First, pure hydrogen was supplied, and it was confirmed that hydrogen could be separated to the secondary side. Subsequently, when the supply gas was switched from hydrogen to ammonia, it was confirmed that ammonia could be decomposed at a conversion rate of about 10%.

[0060] The present disclosure has been explained above based on the examples. These examples are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications are also within the scope of the present disclosure.

[0061] Multiple hydrogen permeable membranes 50 may be connected in series to perform multi-stage hydrogen separation and recovery. That is, the gas that did not permeate the hydrogen permeable membrane 50 in the upstream hydrogen production apparatus 10 may be supplied to the primary side of the downstream hydrogen permeable membrane 50 to separate and recover the hydrogen remaining in the raw material gas again.

[0062] Multiple hydrogen permeable membranes 50 may be installed in parallel in the hydrogen production apparatus 10. Alternatively, multiple hydrogen production apparatuses 10 may be connected in parallel. This allows for the simultaneous production of large quantities of hydrogen. [Explanation of Symbols]

[0063] 10...Hydrogen production device, 11...Primary flange, 12...Secondary flange, 20...Primary SUS flange, 21...Primary support, 22...Primary gasket, 23...Primary gasket, 30...Flow flange, 31a...Straight pipe section, 31b...Expansion section, 32...Discharge channel, 33...Side wall, 34...Baffle, 40...Secondary SUS flange, 41...Secondary support, 42...Secondary gasket, 43...Hydrogen recovery channel, 50...Hydrogen permeable membrane, 51...Ammonia decomposition catalyst, 52...Metal layer, 53a, 53b...Oxide layer, 54...Catalyst-integrated hydrogen permeable membrane.

Claims

1. A hydrogen permeable membrane that allows hydrogen to pass through, A catalyst for a chemical reaction that decomposes ammonia to produce hydrogen and nitrogen is provided on the primary side of the hydrogen permeable membrane, A raw material gas supply channel for supplying a raw material gas containing ammonia to the primary surface of the hydrogen permeable membrane, A hydrogen recovery channel for recovering hydrogen that has permeated to the secondary surface of the hydrogen permeable membrane, Equipped with, The hydrogen permeable membrane has a flat plate shape. Hydrogen production equipment.

2. The hydrogen permeable membrane is formed from a pure metal of a Group 5 element or an alloy in which a Group 5 element is the main metal. The hydrogen production apparatus according to claim 1.

3. The hydrogen permeable membrane is formed of palladium or a palladium alloy. The hydrogen production apparatus according to claim 1.

4. The system includes a distribution unit for distributing the raw material gas supplied from the raw material gas supply channel across the entire catalyst or hydrogen permeable membrane. A hydrogen production apparatus according to any one of claims 1 to 3.

5. It comprises a housing section for housing the catalyst, The containment section is formed with a channel for distributing the raw material gas throughout the catalyst, or for distributing the generated hydrogen throughout the hydrogen permeable membrane. A hydrogen production apparatus according to any one of claims 1 to 3.

6. The hydrogen permeable membrane is provided with a gasket for sealing the primary side, The gasket forms a housing portion for housing the catalyst. A hydrogen production apparatus according to any one of claims 1 to 3.

7. The height of the gasket is adjusted according to the amount, shape, or size of the catalyst. The hydrogen production apparatus according to claim 6.

8. The facility includes side walls for restricting the flow path of gas discharged from the containment section for housing the catalyst to the vicinity of the hydrogen permeable membrane. A hydrogen production apparatus according to any one of claims 1 to 3.

9. A hydrogen permeable membrane that allows hydrogen to pass through, Supported on the primary surface of the hydrogen permeable membrane is a catalyst for a chemical reaction that decomposes ammonia to produce hydrogen and nitrogen, A raw material gas supply channel for supplying a raw material gas containing ammonia to the primary surface of the hydrogen permeable membrane, A hydrogen recovery channel for recovering hydrogen that has permeated to the secondary surface of the hydrogen permeable membrane, A hydrogen production device equipped with the following features.

10. The hydrogen permeable membrane is formed from a pure metal of a Group 5 element or an alloy in which a Group 5 element is the main metal. The hydrogen production apparatus according to claim 9.

11. The hydrogen permeable membrane has oxide layers on both surfaces, The catalyst is supported on the oxide layer. The hydrogen production apparatus according to claim 9 or 10.

12. The hydrogen permeable membrane is formed of palladium or a palladium alloy. The hydrogen production apparatus according to claim 9.

13. A catalyst for a chemical reaction that decomposes ammonia to produce hydrogen and nitrogen is supported on the surface. Hydrogen permeable membrane.

14. The hydrogen permeable membrane is formed from a pure metal of a Group 5 element or an alloy in which a Group 5 element is the main metal. The hydrogen permeable membrane according to claim 13.

15. The hydrogen permeable membrane has oxide layers on both surfaces, The catalyst is supported on the oxide layer. The hydrogen permeable membrane according to claim 13 or 14.

16. The hydrogen permeable membrane is formed of palladium or a palladium alloy. The hydrogen permeable membrane according to claim 13.

17. The steps include forming oxide layers on both surfaces of the hydrogen permeable membrane, The steps include supporting a catalyst for a chemical reaction that decomposes ammonia to produce hydrogen and nitrogen on the primary surface of the hydrogen permeable membrane, A method for producing a hydrogen permeable membrane containing [the specified substance].

18. The hydrogen permeable membrane is formed from a pure metal of a Group 5 element or an alloy in which a Group 5 element is the main metal. The method according to claim 17.

19. The step includes reducing the oxide layer. The method according to claim 18.

20. The hydrogen permeable membrane is formed of palladium or a palladium alloy. The method according to claim 17.

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