Hydrogen gas production method

Abstract

This invention provides a method for efficiently producing hydrogen gas using calcium-containing materials while suppressing excessive consumption of carbon materials and carbon compounds. [Solution] A method for producing hydrogen gas, comprising the steps of: loading calcium-containing powder into a container; and supplying a raw material gas containing water vapor and carbon monoxide gas to the calcium-containing powder inside the container from outside the container, thereby reacting the water vapor and carbon monoxide gas to produce carbon dioxide gas and hydrogen gas, and fixing the carbon dioxide gas to the calcium-containing powder.

Description

Technical Field

[0005]

[0001] The present invention relates to a method for producing hydrogen gas.

Background Art

[0002] In the future, in order to realize a hydrogen society, it is necessary to produce a large amount of hydrogen. Therefore, research has been underway to promote the water gas shift reaction (CO + H2O → CO2 + H2) for hydrogen production. However, in the conventional hydrogen gas production process, it is necessary to fix CO2 and an expensive adsorbent is used. In addition, the problem has been that the treatment of the adsorbent after use requires a large cost.

[0003] Patent Document 1 discloses a method in which superheated steam is brought into contact with a molded body obtained by mixing and molding a carbon compound such as bamboo powder and a calcium compound to generate a combustible gas such as hydrogen gas. Patent Document 2 discloses a method in which water is sprayed when cooling high-temperature slag, the water gasification reaction is allowed to proceed on the inlet side of the cooling device, and the shift reaction is allowed to proceed on the outlet side to generate carbon dioxide gas.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Documents 1 and 2, since steam is converted into hydrogen gas using the carbon contained in the slag, when trying to utilize the slag in actual operation, the C concentration in the slag is low and the hydrogen gas production efficiency is low. In this case, it is necessary to add a carbon material or a carbon compound to increase the C concentration in the slag, and there is a problem of increased consumption of carbon resources such as coal.

[0006] In view of the above issues, the present invention aims to provide a method for efficiently producing hydrogen gas using calcium-containing materials while suppressing excessive consumption of carbon materials and carbon compounds. [Means for solving the problem]

[0007] The inventors of this invention have diligently studied to solve the above problems and have obtained the following findings. By supplying water vapor and carbon monoxide to calcium-containing powder charged in a container and allowing it to react, carbon dioxide gas, which inhibits hydrogen gas generation, can be fixed to the calcium-containing powder. This allows the hydrogen generation reaction to proceed efficiently by directly supplying carbon monoxide gas from an external source without consuming carbon materials or carbon compounds. Furthermore, it is preferable that the calcium-containing powder used at this time has an appropriate particle size, which can be obtained by spontaneous pulverization when the calcium-containing material is cooled.

[0008] In other words, the gist of the present invention is as follows:

[0009] [1] A step of loading calcium-containing powder into a container, A hydrogen gas generation step is performed by supplying a raw material gas containing water vapor and carbon monoxide gas to the calcium-containing powder inside the container from outside the container, thereby reacting the water vapor and carbon monoxide gas to generate carbon dioxide gas and hydrogen gas, while fixing the carbon dioxide gas to the calcium-containing powder. A method for producing hydrogen gas, comprising:

[0010] [2] The method for producing hydrogen gas according to [1] above, wherein the temperature of the calcium-containing powder at the start of the hydrogen gas generation step is 400°C or higher.

[0011] [3] A method for producing hydrogen gas according to [1] or [2] above, further comprising a pretreatment step of micronizing a calcium-containing material to obtain the calcium-containing powder.

[0012] [4] The calcium-containing substance contains dicalcium silicate and has a phosphorus content of 1.00% by mass or less. The method for producing hydrogen gas according to [3] above, wherein the pretreatment step is a spontaneous pulverization step in which the calcium-containing material at 900°C or higher is spontaneously pulverized during the cooling process to become the calcium-containing powder.

[0013] [5] The calcium-containing substance contains dicalcium silicate and has a phosphorus content exceeding 1.00% by mass, The aforementioned pre-treatment step is A step of subjecting the calcium-containing material to a melt reduction treatment to adjust the phosphorus content in the calcium-containing material to 1.00% by mass or less, Next, the calcium-containing material at 900°C or higher undergoes a spontaneous powdering process during the cooling process to become the calcium-containing powder. A method for producing hydrogen gas as described in [3] above, comprising:

[0014] [6] The method for producing hydrogen gas according to [4] or [5] above, wherein in the spontaneous powdering step, the calcium-containing material is slowly cooled at a cooling rate of 500°C / h or less in a temperature range of 850±50°C.

[0015] [7] A method for producing hydrogen gas according to any one of the above [1] to [6], wherein the calcium-containing powder includes steel slag.

[0016] [8] The method for producing hydrogen gas according to [7] above, wherein the steel slag is steelmaking slag.

[0017] [9] A method for producing hydrogen gas according to any one of the above [1] to [8], wherein the raw material gas includes steel mill by-product gas.

[0018]

[10] The method for producing hydrogen gas according to [9] above, wherein the by-product gas of the steelworks is blast furnace gas. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a method for efficiently producing hydrogen gas using a calcium-containing substance while suppressing excessive consumption of carbonaceous materials and carbon compounds.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, a method for producing hydrogen gas according to an embodiment of the present invention will be described. Note that the embodiments described below are examples of embodying the present invention, and do not limit the configuration of the present invention by these specific examples.

[0021] The method for producing hydrogen gas according to an embodiment of the present invention includes a step of charging a calcium-containing powder into a container, and by supplying a raw material gas containing water vapor and carbon monoxide gas from the outside of the container to the calcium-containing powder in the container, reacting the water vapor and the carbon monoxide gas to generate carbon dioxide gas and hydrogen gas, and fixing the carbon dioxide gas to the calcium-containing powder, a hydrogen gas generation step.

[0022] (Step of charging calcium-containing powder) First, a calcium-containing powder is charged into a container used for producing hydrogen gas.

[0023] [Container] The container is not particularly limited as long as it can be charged with the calcium-containing powder and can perform the hydrogen gas generation step described later. As an example, a quartz tube can be used as the container. In actual operation, a packed bed, a kiln, a fluidized bed, etc. in which a metal or refractory container is filled with the calcium-containing powder can be used.

[0024] [Calcium-containing powder] In the present invention, the calcium-containing powder refers to a powder containing a calcium-containing substance and having the property of fixing carbon dioxide gas. As the calcium-containing substance, CaO, tricalcium phosphate, etc. are preferable.

[0025] The calcium-containing powder preferably contains steel slag (hereinafter also simply referred to as "slag"). Furthermore, the steel slag contained in the calcium-containing powder is preferably steelmaking slag. By using the above-mentioned slag as the calcium-containing powder, in addition to the hydrogen gas generation reaction described later, hydrogen gas can be generated from the FeO contained in the slag through reactions such as H2O(g) + 3FeO → H2 + Fe3O4. In addition, by using slag, fine powder of carbonated slag can also be obtained in addition to hydrogen gas.

[0026] When the calcium-containing material that becomes the calcium-containing powder contains Al or Fe, the Al or Fe forms a mineral phase with Ca, inhibiting the phase transformation of dicalcium silicate (chemical formula: 2CaO·SiO2, hereinafter referred to as "C2S") into the γC2S phase. Therefore, the total content of Al and Fe in the calcium-containing material is preferably 20% by mass or less, and more preferably 10% by mass or less. On the other hand, the lower limit of the total content of Al and Fe in the calcium-containing material is not particularly limited and may be 0% by mass.

[0027] (Pre-processing steps) The finer the particle size of the calcium-containing powder, the more efficient the hydrogen gas production becomes, which is therefore preferable. An example of a particle size for calcium-containing powder is when 70% or more by mass is 1.18 mm or smaller, and 20% or more by mass is 0.1 mm or smaller. Another example is when the total particle size is 75 μm or less and 1 μm or larger. Therefore, if the particle size of the calcium-containing material used as calcium-containing powder is not within an appropriate range, it is preferable to perform a pre-treatment step to pulverize the calcium-containing material.

[0028] The method for micronizing calcium-containing material in the pretreatment process is not particularly limited, and the calcium-containing material may be mechanically crushed using a vibrating mill or the like. However, mechanical crushing requires energy and cost. Therefore, the pretreatment process is preferably a spontaneous pulverization process in which the material is micronized by spontaneous pulverization. In actual operation, calcium-containing material such as steel slag is obtained when heated to 900°C or higher, so it is preferable that calcium-containing powder is obtained by spontaneous pulverization during the cooling process of the calcium-containing material. The inventors have discovered conditions under which calcium-containing material spontaneously pulverizes during the cooling process, resulting in a particle size suitable for hydrogen gas generation.

[0029] <Calcium-containing material: Contains dicalcium silicate and has a phosphorus content of 1.00% by mass or less> It is preferable that the calcium-containing material contains dicalcium silicate and has a phosphorus content of 1.00% by mass or less. When the calcium-containing material contains dicalcium silicate and has a low phosphorus content, a volume change occurs when the calcium-containing material is cooled from a high temperature due to a phase transformation of the dicalcium silicate into the γC2S phase, thus facilitating spontaneous pulverization of the calcium-containing material. It is preferable that the composition of the calcium-containing material satisfies the condition that the γC2S phase content is 5% by mass or more upon completion of cooling, as this results in spontaneous pulverization and the majority of the calcium-containing powder having a particle size of 75 μm or less, which is suitable for hydrogen gas generation. On the other hand, there is no particular upper limit to the γC2S phase content upon completion of cooling, but it is generally 80% by mass or less. The γC2S phase content can be determined by Rietveld analysis using X-ray diffraction.

[0030] During the cooling of calcium-containing materials, phosphorus is an element that prevents the phase transformation of the dicalcium silicate phase to the γ-type. Therefore, if the calcium-containing material is cooled while it contains an excess of phosphorus, it is difficult to achieve sufficient spontaneous pulverization, and it is preferable that the phosphorus content of the calcium-containing material be 1.00% by mass or less. Furthermore, if the phosphorus content of the calcium-containing material is 0.20% by mass or less, the spontaneous pulverization of the calcium-containing material is further promoted, and the efficiency of hydrogen gas production is increased, which is preferable. Therefore, it is more preferable that the phosphorus content of the calcium-containing material be 0.20% by mass or less, and even more preferable that be 0.10% by mass or less. On the other hand, the lower limit of the phosphorus content of the calcium-containing material is not particularly limited and may be 0.00% by mass. The phosphorus content of the calcium-containing material can be determined by quantitative analysis using X-ray fluorescence analysis, such as the glass bead method. Here, the phosphorus content of the calcium-containing material is defined as the mass percentage of phosphorus atoms contained in the calcium-containing material or calcium-containing powder.

[0031] (Melting reduction treatment) Calcium-containing materials such as slag generally have a phosphorus content exceeding 1.00% by mass. Therefore, calcium-containing materials that satisfy the above-mentioned phosphorus content requirements are special raw materials such as low-phosphorus slag, which are often difficult to obtain. For this reason, it is preferable to adjust the phosphorus content of calcium-containing materials with high phosphorus content, such as steel slag, which are generally available. The method for adjusting the phosphorus content is not particularly limited, but when the calcium-containing material is steelmaking slag, it is preferable to adjust the phosphorus content by melt reduction treatment. The inventors have found that even with calcium-containing materials with high phosphorus content, by adjusting the phosphorus content by melt reduction treatment, it is possible to obtain a particle size suitable for spontaneous pulverization and hydrogen gas generation. Therefore, when the calcium-containing material contains dicalcium silicate and has a phosphorus content exceeding 1.00% by mass, it is preferable that the pretreatment step includes a step of applying melt reduction treatment to the calcium-containing material to adjust the phosphorus content in the calcium-containing material to 1.00% by mass or less. Furthermore, from the viewpoint of hydrogen gas production efficiency, it is more preferable to adjust the phosphorus content after the melt reduction treatment to 0.20% by mass or less in the pretreatment step, and even more preferable to adjust it to 0.10% by mass or less.

[0032] Melt reduction treatment is a process that adjusts the composition of molten calcium-containing material by applying a reduction treatment. Specifically, the treatment method involves melting the slag at 1600°C using an electric furnace, etc., and then adding by-products such as Si sludge or aluminum dross, or metallic Si or metallic Al, to perform the reduction. Through melt reduction treatment, the FeO in the slag is reduced to M-Fe, and the phosphorus contained in the slag is transferred from the slag to the M-Fe, thereby adjusting the phosphorus content of the slag. In addition, if the calcium-containing material is not steelmaking slag, the phosphorus content can be adjusted by melting metallic iron.

[0033] <Temperature of calcium-containing material during pre-treatment process> The pretreatment step is preferably a spontaneous pulverization step in which a calcium-containing material at a temperature of 900°C or higher spontaneously pulverizes as it cools, resulting in a calcium-containing powder. The spontaneous pulverization step can be effectively carried out when the temperature of the calcium-containing material is 900°C or higher. On the other hand, there is no particular upper limit to the temperature of the calcium-containing material at the start of the pretreatment step, but it is generally 1600°C or lower. This temperature is based on the surface temperature of the calcium-containing material.

[0034] Furthermore, it is preferable that the calcium-containing material is cooled to a temperature of 400°C or higher during the pretreatment process, as this eliminates the need for reheating in the hydrogen gas generation process described later. On the other hand, there is no particular upper limit to the temperature of the calcium-containing material when the pretreatment process is completed, but it is generally 800°C or lower.

[0035] <Cooling rate of the spontaneous powdering process> When cooling calcium-containing materials from a high temperature, the slower the cooling rate, the more likely phase transformation is to occur. Therefore, slow cooling is preferable to rapid cooling such as water cooling because it promotes spontaneous pulverization. Accordingly, the spontaneous pulverization process preferably involves slowly cooling the calcium-containing material at a cooling rate of 500°C / h or less within a temperature range of 850±50°C. This is because the C2S phase undergoes a phase transformation from the α' phase to the γ phase at 850°C, so it is preferable to cool the material at a cooling rate of 500°C / h or less within a temperature range that crosses 850°C. The lower limit of the cooling rate within the temperature range of 850±50°C is not particularly limited, but it is generally 50°C / h or higher. For similar reasons, it is even more preferable to slowly cool the calcium-containing material at a cooling rate of 50°C / h or more and 500°C / h or less within a temperature range of 1100°C to 600°C.

[0036] (Hydrogen gas generation process) Following the step of loading calcium-containing powder into a container, a hydrogen gas generation step is performed. Specifically, a raw material gas containing water vapor and carbon monoxide gas is supplied from outside the container to the calcium-containing powder inside the container. This causes the water vapor and carbon monoxide gas to react to generate carbon dioxide gas and hydrogen gas, while simultaneously fixing the carbon dioxide gas to the calcium-containing powder. Conventionally, a method of generating hydrogen gas from water vapor by a water-gas shift reaction (CO + H2O → CO2 + H2) is known, but as the reaction progresses and the concentrations of the products, carbon dioxide and hydrogen, increase, the reaction stalls, making it difficult to produce hydrogen gas efficiently. Therefore, in conventional methods, carbon material or carbon compounds are supplied as a carbon source, and the reaction is advanced by reducing the concentration of carbon dioxide through a Boudouar reaction (CO2 + C → 2CO) and by utilizing the carbon material for the reduction of water (C + 2H2O → CO2 + 2H2). In contrast, in the present invention, the hydrogen generation reaction can be carried out efficiently by directly supplying carbon monoxide gas from an external source without consuming carbon material or carbon compounds.

[0037] The method for reacting water vapor with carbon monoxide gas is not particularly limited, but for example, calcium-containing powder placed in a container can be used as a packed bed, and the raw material gas can be circulated through the packed bed to carry out the reaction. In addition to a packed bed, the calcium-containing powder may also be in the form of a kiln, a fluidized bed, or the like within the container.

[0038] In the hydrogen gas generation process, the reaction time between water vapor and carbon monoxide gas is preferably 10 minutes or more, from the viewpoint of generating a sufficient amount of hydrogen gas. On the other hand, if the reaction process is carried out for a long time, the temperature of the calcium-containing powder will drop, requiring external heat supply. To avoid the need for external heat supply, the processing time of the hydrogen gas generation process is preferably 120 minutes or less. The processing time of the hydrogen gas generation process refers to the time during which the raw material gas is supplied to the calcium-containing powder.

[0039] [Temperature of calcium-containing powder at the start of the hydrogen gas generation process: 400°C or higher] It is preferable that the temperature of the calcium-containing powder at the start of the hydrogen gas generation process is 400°C or higher, as this can increase the efficiency of hydrogen gas generation. On the other hand, there is no particular upper limit to this temperature, but it is generally 800°C or lower.

[0040] [Raw material gas] In the present invention, the raw material gas is a gas containing water vapor and carbon monoxide gas. The composition of the raw material gas is not particularly limited as long as it can react water vapor and carbon monoxide gas to produce carbon dioxide gas and hydrogen gas. Preferably, the raw material gas contains by-product gas from a steel mill. Furthermore, it is preferable that the by-product gas from a steel mill contained in the raw material gas is blast furnace gas. This allows for the effective utilization of by-product gas from a steel mill. An example of the gas composition of blast furnace gas is a mixed gas with a volume ratio of 1.1 parts carbon monoxide gas, 1.1 parts carbon dioxide gas, 0.1 parts hydrogen gas, and 2.7 parts nitrogen gas.

[0041] The raw material gases may be a mixed gas containing carbon monoxide and an inert gas (such as nitrogen gas), and water vapor gas. In this case, from the viewpoint of efficiently generating hydrogen gas, the flow rate of the mixed gas containing carbon monoxide is preferably 56 NL / (min·kg) per 1 kg of calcium contained in the calcium-containing powder. Similarly, the flow rate of the water vapor gas is preferably 56 NL / (min·kg) or more. Furthermore, the flow rate ratio of the water vapor gas to the mixed gas containing carbon monoxide is preferably such that the ratio of the carbon monoxide flow rate (CO) in the mixed gas to the water vapor flow rate (H2O) in the water vapor gas is 0.1 or more and 1.2 or less.

[0042] In the hydrogen gas generation process, from the viewpoint of efficiently generating hydrogen gas, it is preferable that the temperature of the mixed gas containing carbon monoxide be between 200°C and 800°C. Similarly, it is preferable that the temperature of the water vapor gas be between 200°C and 800°C.

[0043] For processes and conditions not described in this specification, conventional methods may be used. [Examples]

[0044] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below.

[0045] Table 1 shows the calcium-containing materials used in each example except for Comparative Example 1. In Comparative Example 1, the hydrogen gas generation process described later was carried out without using a calcium-containing material. In the examples where the calcium-containing material in Table 1 is labeled as "calcium oxide," reagent-grade calcium oxide was used. In the examples where the calcium-containing material in Table 1 is labeled as "steelmaking slag," the slag was cooled under the conditions shown in Table 1 before use.

[0046] Next, the calcium-containing material was pulverized. In the cases where the pulverization condition in Table 1 is indicated as "vibration mill," the calcium-containing material was pulverized using a vibration mill, and the particle size was reduced to 75 μm or less for the entire material before being used as a sample. In the cases where the pulverization condition in Table 1 is indicated as "spontaneous pulverization," the vibration mill was not used because the calcium-containing material spontaneously pulverized during cooling. The particle size of the spontaneously pulverized calcium-containing material was 75 μm or less for the entire material. In the cases where the melt reduction treatment in Table 1 is indicated as "yes," the calcium-containing material was subjected to a melt reduction treatment, and the phosphorus content was adjusted to the value shown in Table 1 before cooling. Table 1 shows the composition of the calcium-containing powder before the hydrogen gas generation process, after the pulverization and cooling treatments.

[0047] The amounts of calcium-containing powder shown in Table 1 were packed into containers. For Comparative Examples 1-3 and Invention Example 1, a quartz tube with an inner diameter of φ70 mm was used; for Invention Examples 2-6, a quartz tube with an inner diameter of φ100 mm was used; and for Invention Examples 7-10, a quartz tube with an inner diameter of φ150 mm was used.

[0048] Hydrogen gas was generated by blowing a mixture of water vapor and raw material gas onto calcium-containing powder packed in a container for the processing time shown in Table 1. The water vapor was heated to 300°C and the raw material gas to 200°C before mixing. Table 1 shows the temperature of the calcium-containing powder at the start of the hydrogen gas generation process, the composition of the raw material gas, the flow rates of the gas and water vapor, the processing time, and the amount of hydrogen gas generated. In Invention Example 10, blast furnace gas was used as the raw material gas. However, since blast furnace gas contains a small amount of hydrogen, when evaluating the amount of hydrogen gas generated, the amount of hydrogen gas originally contained in the blast furnace gas was subtracted from the amount of hydrogen gas generated.

[0049] [Table 1]

[0050] The comparative examples and inventive examples are described below. As is clear from Table 1, in Comparative Example 1, since no calcium-containing material was used, almost no hydrogen gas was generated. Also, in Comparative Examples 2 and 3, since water vapor or carbon monoxide gas was not supplied, no hydrogen gas was generated. On the other hand, in the inventive example, since carbon monoxide gas and water vapor were supplied, it can be seen that hydrogen gas was generated by the water-gas shift reaction.

[0051] Comparing Invention Example 1 and Invention Example 2, the calcium-containing material in Invention Example 2 is steelmaking slag and contains iron oxide. Therefore, hydrogen gas is also generated by the reaction of iron oxide with water vapor, and it is thought that the amount of hydrogen gas generated is greater than in Invention Example 1.

[0052] Examples 3 and 4 of the invention are variations in which the temperature of the calcium-containing powder at the start of the hydrogen gas generation process is changed compared to Example 2. As is clear from Table 1, the higher the temperature of the calcium-containing powder at the start of the hydrogen gas generation process, the greater the amount of hydrogen gas generated.

[0053] Examples 5, 6, 7, and 8 are examples in which the type of calcium-containing material is changed from Example 4, and steelmaking slag containing dicalcium silicate and with a phosphorus content of 1.00% by mass or less is used. Because the phosphorus content of the calcium-containing material was low, it spontaneously pulverized during cooling, eliminating the need for processing with a vibratory mill. Furthermore, the amount of hydrogen gas generated increased as the phosphorus content of the calcium-containing material decreased.

[0054] Invention Example 9 is an example using steelmaking slag with the same phosphorus content as Invention Example 4, but with the phosphorus content of the calcium-containing material reduced by molten reduction treatment. As a result, a high hydrogen gas generation amount equivalent to that of Invention Examples 5-8, which used steelmaking slag with a low phosphorus content, was obtained.

[0055] Examples 10 and 11 use steelmaking slag with the same phosphorus content as Example 4, but reduce the phosphorus content of the calcium-containing material by melt reduction treatment, and control the cooling rate when cooling the high-temperature slag after melt reduction. In the range of 1100°C to 600°C, Example 10 was slowly cooled at 500°C / h, and Example 11 was slowly cooled at 100°C / h. As a result, the slower the cooling rate, the finer the particle size became, and the greater the amount of hydrogen gas generated.

[0056] Invention Example 12 is an example using steelmaking slag with the same phosphorus content as Invention Example 4, and in the same way as Invention Example 11, calcium-containing powder was prepared. In Invention Example 12, blast furnace gas, a by-product gas of a steelworks, was supplied as the raw material gas. It can be seen that even when the raw material gas is blast furnace gas, it is possible to generate hydrogen gas, as in the other Invention Examples. [Industrial applicability]

[0057] According to the present invention, it is possible to provide a method for efficiently producing hydrogen gas using calcium-containing materials while suppressing excessive consumption of carbon materials and carbon compounds.

Claims

1. The process of loading calcium-containing powder into a container, A hydrogen gas generation step is performed by supplying a raw material gas containing water vapor and carbon monoxide gas to the calcium-containing powder inside the container from outside the container, thereby reacting the water vapor and carbon monoxide gas to generate carbon dioxide gas and hydrogen gas, while fixing the carbon dioxide gas to the calcium-containing powder. A method for producing hydrogen gas, comprising:

2. The method for producing hydrogen gas according to claim 1, wherein the temperature of the calcium-containing powder at the start of the hydrogen gas generation step is 400°C or higher.

3. The method for producing hydrogen gas according to claim 1, further comprising a pretreatment step of micronizing a calcium-containing material to obtain the calcium-containing powder.

4. The calcium-containing substance contains dicalcium silicate and has a phosphorus content of 1.00% by mass or less. The method for producing hydrogen gas according to claim 3, wherein the pretreatment step is a spontaneous pulverization step in which the calcium-containing material at 900°C or higher is spontaneously pulverized during the cooling process to become the calcium-containing powder.

5. The calcium-containing substance contains dicalcium silicate and has a phosphorus content exceeding 1.00% by mass. The aforementioned pre-treatment step is A step of subjecting the calcium-containing material to a melt reduction treatment to adjust the phosphorus content in the calcium-containing material to 1.00% by mass or less, Next, the calcium-containing material at 900°C or higher undergoes a spontaneous powdering process during the cooling process to become the calcium-containing powder. A method for producing hydrogen gas according to claim 3, comprising:

6. The method for producing hydrogen gas according to claim 4 or 5, wherein in the spontaneous powdering step, the calcium-containing material is slowly cooled at a cooling rate of 500°C / h or less in a temperature range of 850 ± 50°C.

7. A method for producing hydrogen gas according to any one of claims 1 to 5, wherein the calcium-containing powder includes steel slag.

8. The method for producing hydrogen gas according to claim 7, wherein the steel slag is steelmaking slag.

9. A method for producing hydrogen gas according to any one of claims 1 to 5, wherein the raw material gas includes by-product gas from a steel mill.

10. The method for producing hydrogen gas according to claim 9, wherein the by-product gas of the steelworks is blast furnace gas.

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