Hydrogen production methods

Abstract

The present invention provides a hydrogen production method and apparatus capable of suppressing poor flow of catalyst particles within a reactor. [Solution] A hydrogen production method for producing hydrogen by directly decomposing hydrocarbons into carbon and hydrogen includes a forming step in which a raw material gas containing hydrocarbons is supplied to a mixture of low-reactive particles, which are particulate matter composed of chemically inert, low-reactive material, and a catalyst inside a reactor to form a fluidized bed of the mixture.

Description

Technical Field

[0001] The present disclosure relates to a hydrogen production method and a hydrogen production apparatus.

Background Art

[0002] Currently, the production of various types of energy relies heavily on fossil fuels such as petroleum, coal, and natural gas. However, from the perspective of global environmental protection, the increase in carbon dioxide emissions released by the combustion of fossil fuels is regarded as a problem. The Paris Agreement, reached in 2015, requires the reduction of carbon dioxide emissions to address the climate change issue, and reducing carbon dioxide emissions from fossil fuel combustion has become an important challenge for thermal power plants and other facilities. While processes for separating and recovering emitted carbon dioxide are being actively studied, technologies for producing energy without emitting carbon dioxide using alternative fuels to fossil fuels are also being investigated.

[0003] Accordingly, hydrogen, a clean fuel that does not emit carbon dioxide when combusted, has attracted attention as an alternative fuel to fossil fuels. Hydrogen can be produced, for example, by steam reforming methane contained in natural gas. However, this production method generates carbon monoxide as a by-product, and carbon monoxide is eventually oxidized and emitted as carbon dioxide. On the other hand, as methods for producing hydrogen from water without using fossil fuels, water electrolysis, photocatalytic methods, and the like have been studied, but these methods require a large amount of energy and have economic problems.

[0004] In response to this, methods for producing hydrogen and carbon by directly decomposing hydrocarbons (hereinafter referred to as "direct hydrocarbon decomposition methods") have been developed. For example, the applicant of this disclosure has developed a direct hydrocarbon decomposition method using an unsupported catalyst, which is an aggregate of iron particles, as described in Patent Document 1. The features of the direct hydrocarbon decomposition method are that it has the potential to produce hydrogen fuel without emitting carbon dioxide, and that the carbon in the hydrocarbon raw material gas can be recovered as solid by-product carbon after hydrogen production. Therefore, from the perspective of decarbonization, it has the potential to be more easily handled and less expensive compared to recovering and storing gaseous carbon dioxide. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 7089235 [Overview of the project] [Problems that the invention aims to solve]

[0006] When a catalyst for the direct decomposition reaction of hydrocarbons (not limited to iron-based unsupported catalysts like those in Patent Document 1) is used in a fluidized bed to carry out a direct decomposition method for hydrocarbons, the catalyst particles, which become smaller in diameter as the reaction progresses, are scattered from the reactor because their terminal velocity becomes lower than the empty velocity. On the other hand, the smaller catalyst particles tend to loosely bind to each other by van der Waals forces, forming aggregates that remain in the bed, and the proportion of aggregates in the bed increases as the reaction progresses. In the initial stages of the reaction, relatively large catalyst particles are present in the fluidized bed, and these catalyst particles collide with the aggregates, breaking them down and suppressing the increase of aggregates. However, as the reaction progresses, the catalyst particles in the fluidized bed become smaller in diameter, and the number of large-diameter particles with enough kinetic energy to break down the aggregates decreases, thus promoting the increase of aggregates. Furthermore, because the aggregates have a low apparent specific gravity and are soft, they do not easily break down even when they collide with each other, and in some cases, the aggregates may even aggregate further. As a result, the proportion of aggregates whose fluidization initiation speed exceeds the empty tower velocity increased, leading to problems such as poor fluidization.

[0007] In view of the circumstances described above, at least one embodiment of this disclosure aims to provide a hydrogen production method and a hydrogen production apparatus capable of suppressing poor flow of catalyst particles in a reactor. [Means for solving the problem]

[0008] To achieve the above objective, the hydrogen production method according to the present disclosure is a hydrogen production method for producing hydrogen by directly decomposing hydrocarbons into carbon and hydrogen, and includes a forming step in which a raw material gas containing hydrocarbons is supplied to a mixture of low-reactive particles, which are particulate matter composed of a chemically inert, low-reactive material, and a catalyst inside a reactor to form a fluidized bed of the mixture.

[0009] Furthermore, the hydrogen production apparatus in this disclosure is a hydrogen production apparatus for producing hydrogen by directly decomposing hydrocarbons into carbon and hydrogen, comprising a reactor, the reactor having a catalyst supply port for supplying a catalyst to the reactor, a raw material gas supply port for supplying a raw material gas containing hydrocarbons to the reactor, and an outlet for the contents of the reactor to flow out, and a mixture of low-reactive particles, which are particulate matter composed of a chemically inert, low-reactivity material, and the catalyst is contained in the reactor so as to be able to form a fluidized bed with the raw material gas supplied into the reactor. [Effects of the Invention]

[0010] According to the hydrogen production method and hydrogen production apparatus of this disclosure, a direct decomposition reaction of hydrocarbons occurs in a fluidized bed formed by a mixture of low-reactive particles and a catalyst inside the reactor. As the reaction progresses, the catalyst particles, which have been reduced in diameter, and carbon that is not attached to the catalyst particles are transported to the upper surface of the fluidized bed by the flowing low-reactive particles and efficiently dispersed from the reactor by the gas flowing out of the reactor. This suppresses an increase in the concentration of reduced-diameter catalyst particles in the fluidized bed, thereby suppressing poor fluidity of catalyst particles inside the reactor. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic diagram illustrating the configuration of a hydrogen production apparatus according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0012] Hereinafter, a hydrogen production method and hydrogen production apparatus according to embodiments of the present disclosure will be described with reference to the drawings. The embodiments described below represent one aspect of the present disclosure and are not limiting, and can be modified at will within the scope of the technical idea of ​​the present disclosure.

[0013] <Configuration of a hydrogen production apparatus according to one embodiment of this disclosure> As shown in Figure 1, a hydrogen production apparatus 1 according to one embodiment of the present disclosure includes a reactor 2. The reactor 2 has a catalyst supply port 3 for supplying a catalyst 10 for the direct decomposition reaction of hydrocarbons to the reactor 2, a raw material gas supply port 4 for supplying a raw material gas containing hydrocarbons to the reactor 2, and an outlet port 5 for the contents of the reactor 2 (specifically described later) to flow out. Pipes 6, 7, and 8 may be connected to the catalyst supply port 3, the raw material gas supply port 4, and the outlet port 5, respectively. A dispersion plate 9 is provided inside the reactor 2 so as to divide the inside of the reactor 2 into two chambers, and the catalyst supply port 3 and the outlet port 5 are each formed on the opposite side of the dispersion plate 9 from the raw material gas supply port 4. Low-reactive particles 11, which are particulate matter composed of a chemically inert, low-reactive material, are housed in the reactor 2 so as to be placed on the dispersion plate 9, that is, on the opposite side of the dispersion plate 9 from the raw material gas supply port 4. The reactor 2 may also have a low-reactive particle supply port 12 for supplying the low-reactive particles 11 to the reactor 2. In this case, the piping 13 may be connected to the low-reactivity particle supply port 12.

[0014] The catalyst 10 for the direct decomposition reaction of hydrocarbons used in this embodiment may be, but is not limited to, an unsupported catalyst in the form of an aggregate of iron particles as described in Patent Document 1. For example, an unsupported catalyst in the form of an aggregate of multiple particles of nickel-based metals or cobalt-based metals, alloys thereof, or oxides thereof, an aggregate of multiple particles made from a mineral containing at least one of iron-based metals, nickel-based metals, or cobalt-based metals, or a supported catalyst in which at least one of iron-based metals, nickel-based metals, or cobalt-based metals is supported on a carrier can also be used.

[0015] The low-reactive particles 11 need to be unaffected even at the temperature at which the direct decomposition reaction of hydrocarbons occurs in the reactor 2, and therefore need to have a heat resistance temperature of 600°C or higher, preferably 650°C, and more preferably 750°C or higher. Furthermore, as will be described in detail later, while the direct decomposition reaction of hydrocarbons is occurring in the reactor 2, the low-reactive particles 11 form a fluidized bed, and the catalyst 10 is supplied into this fluidized bed. For this reason, the catalyst 10 and the low-reactive particles 11 rub against each other, so in order for the low-reactive particles 11 to continue forming a fluidized bed, the low-reactive particles 11 need to be harder than the catalyst 10. Specifically, the Vickers hardness of the low-reactive particles 11 should be greater than the Vickers hardness of the catalyst 10, and depending on the type of metal that makes up the catalyst 10, the Vickers hardness of the low-reactive particles 11 is 10 Hv or higher, preferably 50 Hv or higher, and more preferably 70 Hv or higher. In this embodiment, if catalyst 10 is a supported catalyst, the hardness of catalyst 10 refers to the hardness of the support, and the Vickers hardness of catalyst 10 also refers to the Vickers hardness of the support. Furthermore, since the generated carbon is generally less hard than the catalyst particles, setting the hardness of the low-reactivity particles as described above can be expected to wear down and detach the carbon deposited on the reactor wall and layer inlay by the thermal decomposition reaction, thereby suppressing its growth.

[0016] The low-reactivity particles 11 are not particularly limited as long as they are particulate matter having the above-described structure and composed of a chemically inert, low-reactivity material. For example, they may be particles composed of silicon dioxide, such as silica sand, shirasu balloons, and silica balls; particles composed of alumina, such as alumina balls; particles composed of a mixture of silicon dioxide and alumina, such as blast furnace slag, coal gasification slag, and waste gasification melting furnace slag; or particles composed of magnesia, calcium oxide, silicon carbide, silicon nitride, yttonia, titania, or cordierite.

[0017] The raw material gas may contain not only hydrocarbons but also noble gases such as argon, inert gases such as nitrogen, or hydrogen, or both. Furthermore, the hydrocarbons contained in the raw material gas may be saturated hydrocarbons such as methane, ethane, or propane, or unsaturated hydrocarbons such as ethylene, propylene, or acetylene, or a mixture of at least two of these.

[0018] <Operation of a hydrogen production apparatus according to one embodiment of this disclosure> Next, the operation of a hydrogen production apparatus (hydrogen production method) according to one embodiment of the present disclosure will be described. As shown in Figure 1, a fluidized bed of mixture 14 is formed inside the reactor 2 by supplying a raw material gas to the mixture 14 of low-reactive particles 11 and catalyst 10. The operation of forming the fluidized bed of mixture 14 is not particularly limited and may be carried out by, for example, the following operation. First, low-reactive particles 11 are supplied into the reactor 2. The supply of low-reactive particles 11 to the reactor 2 may be done via the low-reactive particle supply port 12 if such a port is formed in the reactor 2, or via the catalyst supply port 3 or the outlet port 5 if the low-reactive particle supply port 12 is not formed in the reactor 2. Next, the raw material gas is supplied to the reactor 2 via the raw material gas supply port 4. The raw material gas supplied to the reactor 2 passes through the dispersion plate 9, then through the layer of low-reactive particles 11, and then flows out of the reactor 2 via the outlet port 5. As the raw material gas passes through the layer of low-reactive particles 11, the low-reactive particles 11 are made to flow, forming a fluidized bed of low-reactive particles 11 in the reactor 2.

[0019] A fluidized bed of mixture 14 can also be formed by the following example operations: Low-reactive particles 11 and catalyst 10 may be supplied into reactor 2 (the order of supplying the low-reactive particles 11 and catalyst 10 to reactor 2 is not limited and they may be supplied simultaneously), and raw material gas may be supplied to reactor 2 containing the low-reactive particles 11 and catalyst 10. Alternatively, catalyst 10 may be supplied into reactor 2, raw material gas may be supplied to reactor 2 containing catalyst 10, and then low-reactive particles 11 may be supplied to reactor 2.

[0020] Furthermore, in order to form a fluidized bed of the mixture 14 in the reactor 2, it is necessary that the superficial velocity of the raw material gas in the reactor 2 is not less than the fluidization initiation velocity of the low-reactivity particles 11 and less than the terminal velocity of the low-reactivity particles 11. Preferably, in the reactor 2, it is desirable that the superficial velocity of the raw material gas is not less than 3 times the fluidization initiation velocity of the low-reactivity particles 11 and less than the terminal velocity of the low-reactivity particles 11. Furthermore, since the fluidization initiation velocity and the terminal velocity can be calculated by known methods, the above conditions can be easily set by those skilled in the art. Under these conditions, the catalyst with reduced diameter, which will be described later, can be scattered out of the reactor 2, while the low-reactivity particles 11 can be retained in the reactor 2. By selecting the low-reactivity particles 11 and the superficial velocity of the raw material gas in the reactor 2 so as to satisfy such conditions, the fluidized bed of the mixture 14 can be formed in the reactor 2.

[0021] In the fluidized bed of the mixture 14 in the reactor 2, the hydrocarbon and the catalyst 10 can come into good contact with each other, so that the catalyst 10 can favorably exert a catalytic effect on the direct decomposition reaction of hydrocarbon. Through this catalytic action, hydrocarbon is directly decomposed into hydrogen and carbon.

[0022] Since the raw material gas is continuously supplied to the reactor 2, the hydrogen generated by the direct decomposition reaction of hydrocarbon flows out of the reactor 2 through the outflow port 5 together with unreacted hydrocarbon (if the raw material gas contains inert gas or hydrogen, they are also included together). By purifying the outflow gas flowing out of the reactor 2 through the outflow port 5 with a hydrogen production apparatus not shown in the figure, a gas having a higher hydrogen concentration than the outflow gas can be obtained.

[0023] Carbon produced by the direct decomposition reaction of hydrocarbons partially adheres to the catalyst 10. Carbon that does not adhere to the catalyst 10 is transported to the upper surface of the fluidized bed by flowing together with the catalyst 10 and the low-reactivity particles 11. Since carbon has a lower density than the low-reactivity particles 11, it is entrained by the gas flowing toward the outflow port in the reactor 2, and flows out of the reactor 2 through the outflow port 5. Carbon entrained in the outflow gas flowing out from the reactor 2 can be separated from the outflow gas and recovered by a solid-gas separation device (not shown).

[0024] Part of the carbon adhering to the catalyst 10 is peeled off from the catalyst 10 by friction between the catalyst 10 and the low-reactivity particles 11. The carbon peeled off from the catalyst 10 flows out of the reactor 2 and is recovered in the same manner as the carbon that does not adhere to the catalyst 10 described above.

[0025] The catalyst 10 is reduced in particle diameter by the catalytic action of the direct decomposition reaction of hydrocarbons. The catalyst particles with reduced diameter are carried by the flowing low-reactivity particles 11 to the upper surface of the fluidized bed, and are entrained by the gas flowing toward the outflow port in the reactor 2 in the same manner as the carbon described above, so that they flow out of the reactor 2 through the outflow port 5. The catalyst particles entrained in the outflow gas flowing out from the reactor 2 can be separated from the outflow gas and recovered by a solid-gas separation device (not shown).

[0026] As described above, carbon and the diameter-reduced catalyst particles are entrained in the outflow gas from the reactor 2 and efficiently scattered out of the reactor 2, and the increase in the concentration of the diameter-reduced catalyst particles in the fluidized bed of the mixture 14 is suppressed, so that poor fluidization of catalyst particles in the reactor 2 can be suppressed.

[0027] Regarding the usable particle size range for the low-reactivity particles 11, the minimum average particle size is determined by ensuring that the low-reactivity particles 11 are in a region where they can flow independently, avoiding the C particle (a difficult-to-flow particle, generally classified by particle size and density) region, and that the terminal velocity is greater than the empty column velocity. The maximum average particle size is determined by the particle size that ensures the empty column velocity is at least three times the fluidization initiation velocity. For example, if the low-reactivity particles 11 are silica sand and methane at 600°C to 900°C is operated at an empty column velocity of 0.05 m / sec to 0.2 m / sec, it is preferable that the average particle size of the low-reactivity particles 11 be between 20 μm and 300 μm.

[0028] The concentration of the low-reactive particles 11 in the mixture 14 is preferably 20 wt% or more, and more preferably 40 wt% or more.

[0029] The contents described in each of the above embodiments can be understood, for example, as follows:

[0030] [1] A hydrogen production method according to one embodiment is: A method for producing hydrogen by directly decomposing hydrocarbons into carbon and hydrogen, The process includes a forming step in which a fluidized bed of a mixture (14) is formed by supplying a raw material gas containing hydrocarbons to a mixture (14) of low-reactive particles (11), which are particulate matter composed of a chemically inert, low-reactive material, and a catalyst (10) inside a reactor (2).

[0031] According to the hydrogen production method of this disclosure, a direct decomposition reaction of hydrocarbons occurs in a reactor where a mixture of low-reactivity particles and a catalyst forms a fluidized bed. As the reaction progresses, the catalyst particles, which have been reduced in diameter, and carbon that is not attached to the catalyst particles are transported to the upper surface of the fluidized bed by the flowing low-reactivity particles. These particles are then carried out of the reactor by the gas flowing out, and efficiently dispersed from the reactor. This suppresses an increase in the concentration of reduced-diameter catalyst particles in the fluidized bed, thereby preventing poor fluidity of catalyst particles within the reactor.

[0032] [2] Another embodiment of the hydrogen production method is the hydrogen production method of [1], The forming step is, The steps include supplying the low-reactive particles (11) into the reactor (2), The steps include supplying the raw material gas to the reactor (2) to form a fluidized bed of the low-reactive particles (11), The steps include supplying the catalyst (10) into the reactor (2) where the fluidized bed of the low-reactive particles is formed, and Includes.

[0033] This method can suppress poor flow of catalyst particles in the reactor for the same reasons as described in [1] above.

[0034] [3] A further embodiment of the hydrogen production method is the hydrogen production method of [1], The forming step is, The steps include supplying the low-reactive particles (11) and the catalyst (10) into the reactor (2), The steps include supplying the raw material gas to the reactor (2) containing the low-reactive particles (11) and the catalyst (10), and Includes.

[0035] This method can suppress poor flow of catalyst particles in the reactor for the same reasons as described in [1] above.

[0036] [4] A further embodiment of the hydrogen production method is the hydrogen production method of [1], The forming step is, The steps include supplying the catalyst (10) into the reactor (2), The steps include supplying the raw material gas to the reactor (2) containing the catalyst (10), The steps include supplying the low-reactive particles (11) to the reactor (2) containing the catalyst (10), and Includes.

[0037] This method can suppress poor flow of catalyst particles in the reactor for the same reasons as described in [1] above.

[0038] [5] A further embodiment of the direct decomposition of hydrocarbons is a hydrogen production method of any of [1] to [4], The heat resistance temperature of the low-reactivity particles (11) is 600°C or higher.

[0039] This method allows low-reactivity particles to form a fluidized bed without being affected by temperature, even at temperatures where direct hydrocarbon decomposition reactions occur, thereby suppressing poor fluidity of catalyst particles within the reactor.

[0040] [6] A further embodiment of the direct decomposition of hydrocarbons is a hydrogen production method of any of [1] to [5], In the reactor (2), the empty velocity of the raw material gas is set to be equal to or greater than the fluidization initiation velocity of the low-reactive particles (11) and less than the terminal velocity of the low-reactive particles (11).

[0041] With this method, the reduced-diameter catalyst can be scattered from the reactor, while the less reactive particles can be retained within the reactor.

[0042] [7] A further embodiment of the direct decomposition of hydrocarbons is a hydrogen production method of any of [1] to [5], In the reactor (2), the empty velocity of the raw material gas is set to at least three times the fluidization initiation velocity of the low-reactive particles (11) and less than the terminal velocity of the low-reactive particles (11).

[0043] With this method, the reduced-diameter catalyst can be scattered from the reactor, while the less reactive particles can be retained within the reactor, allowing for a more stable formation and maintenance of the fluidized bed.

[0044] [8] A further embodiment of the direct decomposition of hydrocarbons is a direct decomposition of hydrocarbons method of any of [1] to [7], The Vickers hardness of the low-reactivity particles (11) is greater than that of the catalyst (10).

[0045] This method allows for the direct decomposition reaction of hydrocarbons to be promoted because the low-reactive particles and the catalyst rub against each other, preventing the former from being destroyed, while the latter are reduced in size by the former. Furthermore, since carbon is softer than catalyst particles, as the reaction progresses, the carbon is detached from the catalyst particles by friction between the attached catalyst particles and the low-reactive particles, allowing for efficient carbon dispersion from the reactor.

[0046] [9] A hydrogen production apparatus according to one embodiment is: A hydrogen production apparatus (1) for producing hydrogen by directly decomposing hydrocarbons into carbon and hydrogen, Equipped with reactor (2), The reactor (2) includes: A catalyst supply port (3) for supplying catalyst (10) to the reactor (2), A raw material gas supply port (4) for supplying a raw material gas containing hydrocarbons to the reactor (2), An outlet (5) for the contents of the reactor (2) to flow out and Formed, A mixture of low-reactive particles (11), which are particulate matter composed of a chemically inert, low-reactive material, and the catalyst is contained within the reactor (2) so that a fluidized bed can be formed by the raw material gas supplied into the reactor (2).

[0047] According to the hydrogen production apparatus of this disclosure, a direct decomposition reaction of hydrocarbons occurs in a fluidized bed formed by a mixture of low-reactivity particles and a catalyst inside the reactor. As the reaction progresses, the catalyst particles, which have been reduced in diameter, and carbon that is not attached to the catalyst particles are transported to the upper surface of the fluidized bed by the flowing low-reactivity particles and efficiently dispersed from the reactor by the gas flowing out of the reactor. This suppresses an increase in the concentration of reduced-diameter catalyst particles in the fluidized bed, thereby suppressing poor fluidity of catalyst particles inside the reactor.

[0048]

[10] A hydrogen production apparatus according to another embodiment is the hydrogen production apparatus of [9], The reactor (2) is further provided with a low-reactivity particle supply port (12) for supplying the low-reactivity particles (11).

[0049] With this configuration, low-reactivity particles can be supplied to the reactor even while the raw material gas and catalyst are being supplied to the reactor.

[0050]

[11] A hydrogen production apparatus according to yet another embodiment is the hydrogen production apparatus of [9] or

[10] , The heat resistance temperature of the low-reactivity particles (11) is 600°C or higher.

[0051] With this configuration, even at temperatures where direct hydrocarbon decomposition reactions occur, low-reactivity particles can form a fluidized bed without being affected by temperature, thus suppressing poor fluidity of catalyst particles within the reactor.

[0052]

[12] A hydrogen production apparatus according to yet another embodiment is any of the hydrogen production apparatuses in [9] to

[11] , The Vickers hardness of the low-reactivity particles (11) is greater than that of the catalyst (10).

[0053] With this configuration, the friction between the low-reactive particles and the catalyst prevents the former from being destroyed, while the latter is reduced in size by the former, thus promoting the direct decomposition reaction of hydrocarbons. Furthermore, since carbon is softer than catalyst particles, as the reaction progresses, the carbon is detached from the catalyst particles by friction between the attached catalyst particles and the low-reactive particles, allowing for efficient carbon dispersion from the reactor. [Explanation of Symbols]

[0054] 1. Hydrogen production equipment 2 Reactors 3. Catalyst supply port 4. Raw material gas supply port 5 Outlet 10 Catalyst 11. Low-reactive particles 12 Low-reactivity particle supply port 14 mixture

Claims

1. A method for producing hydrogen by directly decomposing hydrocarbons into carbon and hydrogen, A method for producing hydrogen, comprising a forming step of supplying a raw material gas containing hydrocarbons to a mixture of low-reactive particles, which are particulate matter composed of a chemically inert, low-reactive material, and a catalyst inside a reactor, thereby forming a fluidized bed of the mixture.

2. The forming step is, The steps include supplying the low-reactivity particles into the reactor, The steps include: supplying the raw material gas to the reactor to form a fluidized bed of the low-reactive particles; The steps include: supplying the catalyst into the reactor after a fluidized bed of the low-reactivity particles has been formed; A hydrogen production method according to claim 1, including the following:

3. The forming step is, The steps include supplying the low-reactivity particles and the catalyst into the reactor, The steps include supplying the raw material gas to the reactor containing the low-reactive particles and the catalyst, and A method for producing hydrogen according to claim 1, including the method described in claim 1.

4. The forming step is, The steps include supplying the catalyst into the reactor, The steps include supplying the raw material gas to the reactor containing the catalyst, The steps include supplying the low-reactive particles to the reactor containing the catalyst, A hydrogen production method according to claim 1, including the following:

5. The hydrogen production method according to any one of claims 1 to 4, wherein the heat resistance temperature of the low-reactivity particles is 600°C or higher.

6. A method for producing hydrogen according to any one of claims 1 to 4, wherein in the reactor, the empty velocity of the raw material gas is set to be equal to or greater than the fluidization start velocity of the low-reactive particles and less than the terminal velocity of the low-reactive particles.

7. A method for producing hydrogen according to any one of claims 1 to 4, wherein in the reactor, the empty velocity of the raw material gas is set to three times or more the fluidization start velocity of the low-reactive particles and less than the terminal velocity of the low-reactive particles.

8. The hydrogen production method according to any one of claims 1 to 4, wherein the Vickers hardness of the low-reactivity particles is greater than the Vickers hardness of the catalyst.

9. A hydrogen production apparatus for producing hydrogen by directly decomposing hydrocarbons into carbon and hydrogen, Equipped with a reactor, The reactor includes, A catalyst supply port for supplying catalyst to the reactor, The reactor includes a raw material gas supply port for supplying a raw material gas containing hydrocarbons, An outlet for the contents of the reactor to flow out and Formed, A hydrogen production apparatus comprising a reactor in which a mixture of low-reactive particles, which are particulate matter composed of a chemically inert, low-reactive material, and the catalyst is housed in the reactor so as to be able to form a fluidized bed with the raw material gas supplied into the reactor.

10. The hydrogen production apparatus according to claim 9, further comprising a low-reactive particle supply port for supplying the low-reactive particles to the reactor.

11. The hydrogen production apparatus according to claim 9 or 10, wherein the heat resistance temperature of the low-reactivity particles is 600°C or higher.

12. The hydrogen production apparatus according to claim 9 or 10, wherein the Vickers hardness of the low-reactivity particles is greater than that of the catalyst.

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