Method for producing hydrogen and hydrogen production system

Abstract

To provide a novel production technique of hydrogen which uses biological resources-derived matters such as an organic compound and plant biomass as raw materials.SOLUTION: A solid-containing mixture formed by mixing a solid or liquid first organic raw material made of an organic compound, and a second solid raw material made of solid alkali metal hydroxide is held at a prescribed temperature of 20°C to 300°C to generate hydrogen from the solid-containing mixture. A solid state mixture formed by mixing a first solid raw material derived from plant biomass or microorganism, and a second solid raw material made of solid alkali metal hydroxide is held at a prescribed temperature of 20°C to 300°C to generate hydrogen from the solid state mixture. Woody biomass is exemplified as the plant biomass. Wood fragments, wood chips, saw dust, wood flour, cellulose, lignin sulfonic acid or a salt thereof, and glucose are exemplified as the first solid raw material. Sodium hydroxide and potassium hydroxide are exemplified as the alkali metal hydroxide.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing hydrogen and a hydrogen production system. [Background technology]

[0002] One known method for producing hydrogen is to use fossil resources as raw materials. For example, hydrogen can be produced by gasifying coal at high temperatures of over 400°C. However, this method usually requires high-temperature processing, as reactions at around 1000°C are often used. Therefore, the raw materials must be processed in an inert atmosphere. It is also necessary to remove the large amount of carbon dioxide that is produced as a by-product.

[0003] Biomass is defined as a renewable, organic resource derived from living organisms (excluding fossil fuels). Hydrogen production technologies that use biomass as a raw material are also known. One example is a technology that uses hydrogen fermentation (for example, Patent Document 1). However, this technology has problems such as the need for many chemical substances to cultivate microorganisms, the need for aseptic operation to prevent contamination with various bacteria, and the need for an air-blocking device to perform anaerobic fermentation. Another example is a gasification technology that performs high-temperature treatment of biomass raw materials at about 350°C or higher in an inert atmosphere. However, this technology also has problems such as the need for high-temperature treatment and the need to block air. In addition, this technology also requires the removal of a large amount of carbon dioxide, which is a by-product, in order to increase the purity of hydrogen. In addition, there is a problem that a liquid called tar is generated, which solidifies when cooled and clogs the piping of the device.

[0004] In relation to hydrogen production technology using plant-derived biomass (plant biomass) as a raw material, Non-Patent Document 1 discloses a technology for producing hydrogen by reacting cellulose with sodium hydroxide and water vapor. Specifically, a mixture of cellulose and a 50% aqueous sodium hydroxide solution is exposed to water vapor accompanied by argon gas, and heated to about 200 to 500°C to generate hydrogen. This technology is said to be capable of producing high-purity hydrogen that does not contain carbon monoxide or carbon dioxide. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-3077 [Non-patent literature]

[0006] [Non-Patent Document 1] Minoru Ishida et al., "Production of COx-Free Hydrogen from Biomass and NaOH Mixture: Effect of Catalysts", Energy & Fuels 2006, 20, 748-753 Summary of the Invention [Problem to be solved by the invention]

[0007] In the technology described in Non-Patent Document 1, an aqueous solution of sodium hydroxide is used, and the mixture (reactant) that generates hydrogen is in a liquid state. Therefore, the reactant is not easy to handle. In addition, the process needs to be carried out in an inert atmosphere that does not contain oxygen, such as an argon gas atmosphere, and further, water vapor is required for the reaction, making the operation complicated.

[0008] Therefore, an object of the present invention is to provide a hydrogen production technology that uses organic compounds, particularly substances derived from biological resources such as plant biomass, as raw materials, which makes it easy to handle reactants and enables hydrogen to be produced by simpler operations. [Means for solving the problem]

[0009] One aspect of the present invention is a method for producing hydrogen, comprising: maintaining a solid-containing mixture obtained by mixing a first organic raw material that is a solid or liquid and is made of an organic compound with a second solid raw material that is a solid alkali metal hydroxide at a predetermined temperature of 20°C to 300°C; and generating hydrogen from the solid-containing mixture.

[0010] In the hydrogen production method of this embodiment, a first organic raw material, which is a solid or liquid organic compound, and a second solid raw material, which is a solid alkali metal hydroxide, are used. Then, a solid-containing mixture obtained by mixing these is maintained at a predetermined temperature, and hydrogen is generated from the solid-containing mixture. In the method of this embodiment, since a solid alkali metal hydroxide is used, the reactants are easy to handle. In addition, it is only necessary to simply maintain the solid-containing mixture at a predetermined temperature, and other raw materials and operations, such as water vapor, are not required. No special catalyst is required. In addition, since the method can be carried out under an atmosphere containing oxygen (for example, under an air atmosphere) or an atmosphere containing carbon dioxide, there is no need to use an inert gas such as argon, and the operation is simple. Furthermore, since the temperature is maintained at a predetermined temperature of 20°C to 300°C, the generation of tar is suppressed.

[0011] One aspect of the present invention is a method for producing hydrogen, comprising: mixing a first solid raw material derived from a plant biomass or a microorganism with a second solid raw material comprising a solid alkali metal hydroxide; maintaining a solid mixture at a predetermined temperature of 20°C to 300°C; and generating hydrogen from the solid mixture.

[0012] In the hydrogen production method of this embodiment, a first solid raw material derived from plant biomass or microorganisms and a second solid raw material consisting of a solid alkali metal hydroxide are used. Then, a solid mixture obtained by mixing these is kept at a predetermined temperature, and hydrogen is generated from the solid mixture. In the method of this embodiment, a solid alkali metal hydroxide is used, and the reactant that generates hydrogen is in a solid state, so that the reactant can be easily handled. In addition, it is only necessary to keep the solid mixture at a predetermined temperature, and other raw materials and operations, such as water vapor, are not required. No special catalyst is required. Furthermore, since the method can be carried out under an atmosphere containing oxygen (for example, under an air atmosphere) or an atmosphere containing carbon dioxide, there is no need to use an inert gas such as argon, and the operation is simple. Furthermore, since the temperature is kept at a predetermined temperature of 20°C to 300°C, the generation of tar is suppressed.

[0013] Preferably, the first solid feedstock is derived from woody biomass.

[0014] Preferably, the first solid raw material is at least one selected from the group consisting of wood chips, wood chips, wood waste, wood flour, cellulose, lignosulfonic acid or a salt thereof, and glucose.

[0015] Preferably, the alkali metal hydroxide is sodium hydroxide or potassium hydroxide.

[0016] Preferably, the solid-containing mixture or the solid-state mixture is maintained at the predetermined temperature for 1 minute or more.

[0017] Preferably, the solid-containing mixture or the solid-state mixture is maintained at the predetermined temperature while being stirred.

[0018] Preferably, the reaction is carried out in an atmosphere containing 15% by volume or more of oxygen.

[0019] With this configuration, for example, hydrogen can be generated in an air atmosphere.

[0020] Preferably, the reaction is carried out in an atmosphere containing 15% by volume or more of carbon dioxide.

[0021] In this embodiment, the reaction is carried out in an atmosphere containing a large amount of carbon dioxide, and this configuration makes it possible to obtain higher hydrogen productivity.

[0022] Preferably, the first solid raw material is derived from woody biomass, the alkali metal hydroxide is sodium hydroxide or potassium hydroxide, and the solid mixture is held at the predetermined temperature for 1 minute or more while being stirred, in an atmosphere containing 15 volume % or more of oxygen.

[0023] Preferably, the first solid raw material is derived from woody biomass, the alkali metal hydroxide is sodium hydroxide or potassium hydroxide, and the solid mixture is kept at the predetermined temperature for one minute or more while being stirred, in an atmosphere containing 15 volume % or more of carbon dioxide.

[0024] One aspect of the present invention is a hydrogen production system used in the above-mentioned hydrogen production method, which includes a reaction vessel capable of containing a solid-containing material or solid material and maintaining the predetermined temperature, and the solid-containing mixture or the solid-state mixture is contained in the reaction vessel.

[0025] The hydrogen production system of this embodiment includes a reaction vessel containing the solid-containing mixture or the solid-state mixture. According to this embodiment, the hydrogen production method described above can be carried out more simply.

[0026] Preferably, the solid-containing mixture or the solid-state mixture can be maintained at the predetermined temperature in the reaction vessel.

[0027] Preferably, the solid-containing mixture or the solid-state mixture is stirrable in the reaction vessel.

[0028] Preferably, the system further comprises a hydrogen isolation and purification means for isolating and purifying hydrogen generated from the solid-containing mixture or the solid-state mixture.

[0029] With this configuration, the process from hydrogen generation to isolation and purification can be carried out. Effect of the Invention

[0030] According to the present invention, there is provided a hydrogen production technology using biological resource-derived materials such as organic compounds and plant biomass as raw materials, which makes it easy to handle reactants and enables hydrogen to be produced through simpler operations. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] A method for producing hydrogen according to one aspect of the present invention comprises maintaining a solid-containing mixture, obtained by mixing a first organic raw material, which is a solid or liquid organic compound, with a second solid raw material, which is a solid alkali metal hydroxide, at a predetermined temperature to generate hydrogen. A method for producing hydrogen according to one aspect of the present invention comprises maintaining a solid mixture, obtained by mixing a first solid raw material derived from a plant biomass or a microorganism with a second solid raw material, which is a solid alkali metal hydroxide, at a predetermined temperature to generate hydrogen. In the following description, the first organic raw material and the first solid raw material may be collectively referred to as the "first raw material".

[0032] <First organic raw material> In a hydrogen production method according to an embodiment of the present invention, a solid or liquid first organic raw material made of an organic compound is used. The organic compound is not particularly limited, and various organic compounds belonging to alcohols, ethers, aldehydes, carboxylic acids, carboxylates, esters, sugars, sugar alcohols, etc., can be used. When a liquid organic compound is used, an organic compound in which an alkali metal hydroxide is not dissolved is preferable. The first organic raw material made of a solid organic compound includes the first solid raw material described below.

[0033] Specific examples of the organic compounds include monohydric alcohols such as ethanol and propanol; dihydric alcohols such as ethylene glycol; trihydric alcohols such as glycerin; sugar alcohols such as erythritol, sorbitol, and inositol; aldehydes such as formaldehyde, acetaldehyde, and hexanal; hydroxy acids such as glycolic acid and hydroxybutanoic acid; hydroxy acid salts such as sodium hydroxybutanoate; carboxylic acids such as gluconic acid; carboxylates such as sodium isosaccharinate; uronic acids such as glucuronic acid; monosaccharides such as glucose, galactose, mannose, fructose, xylose, xylulose, and arabinose; disaccharides such as maltose, cellobiose, trehalose, lactose, and sucrose; polysaccharides such as starch, cellulose, hemicellulose, chitin, and chitosan. These organic compounds may be used alone or in combination of two or more. Some of these organic compounds also fall under the category of biomass and plant biomass, which will be described later.

[0034] <First solid raw material> In a method for producing hydrogen according to one embodiment of the present invention, a first solid raw material derived from plant biomass or a microorganism is used. Here, plant biomass refers to biomass derived from a plant. In general, plant biomass contains cellulose, hemicellulose, and lignin. The plant biomass in this embodiment includes at least woody biomass derived from woody plants (also called woody biomass or woody biomass) and herbaceous biomass derived from herbaceous plants. The plant biomass in this embodiment also includes at least that derived from construction waste and agricultural waste.

[0035] Specific examples of plant biomass include biomass derived from wood, bamboo grass, bamboo, rush grass, straw, rice husks, palm trees, etc.; biomass derived from sugar and starch crops such as rice, sugar beet, sugarcane, corn, and potatoes; biomass derived from agricultural and forestry resources and their wastes, such as pulp, paper, waste paper, cotton, fiber, wood board, corn stover, and bagasse. Examples of wood include wood chips, wood chips, wood waste, and wood flour derived from coniferous trees such as pine, cedar, and cypress, and broad-leaved trees such as beech, poplar, and birch. Examples of fibers include wood fiber, cotton fiber, silk fiber, and regenerated cellulose fiber. Examples of wood boards include plywood, laminated lumber, laminated veneer lumber, insulation board, medium-density fiberboard, and hardboard.

[0036] Other examples of plant biomass include compounds obtained from plants, such as cellulose, hemicellulose, lignin decomposition products, lignin sulfonic acid, lignin sulfonates such as sodium lignin sulfonate, glucose, etc. These compounds may be crude extracts or purified products. Lignin and lignin sulfonates, which are by-products of the paper pulp manufacturing process, are preferred examples of the first solid raw material.

[0037] These plant biomasses may be used alone or in combination of two or more. These plant biomasses may be used as the first solid raw material without any restrictions, as long as they are solid.

[0038] The microorganisms include bacteria, yeast, fungi, algae, etc. Fungi include fruiting bodies (mushrooms). The first solid raw material derived from a microorganism includes polysaccharides produced by a microorganism. For example, the exopolysaccharides of mushrooms, the polysaccharides constituting the cell wall of yeast, and the polysaccharides constituting the cell membrane of gram-negative bacteria are included. Other examples include hyaluronic acid, fucoidan, carrageenan, etc. contained in algae. These compounds may be crude extracts or purified products. The first solid raw material derived from these microorganisms may be used alone or in combination of two or more.

[0039] In a preferred embodiment, the first solid raw material is at least one selected from the group consisting of wood chips, wood chips, wood waste, wood flour, cellulose, lignosulfonic acid or a salt thereof, and glucose.

[0040] The shape of the first solid raw material is not particularly limited as long as it can generate hydrogen upon contact with the second solid raw material described below.

[0041] <Second solid raw material> In a method for producing hydrogen according to one embodiment of the present invention, a second solid raw material made of a solid alkali metal hydroxide is used. Examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, and lithium hydroxide. In one preferred embodiment, sodium hydroxide or potassium hydroxide is used as the alkali metal hydroxide. The shape of the second solid raw material is not particularly limited as long as it is solid, and may be any shape such as granular, granular, or flaky. For example, granular sodium hydroxide can be used as it is.

[0042] <Solid-containing mixture> In a hydrogen production method according to one embodiment of the present invention, hydrogen is generated from a solid-containing mixture obtained by mixing a first organic raw material and a second solid raw material. The solid-containing mixture contains at least a solid alkali metal hydroxide. The solid-containing mixture may be in the form of a liquid or a solid. In the case of a liquid solid-containing mixture, it is preferable that the solid alkali metal hydroxide is dispersed in the mixture. From the viewpoint of hydrogen production efficiency, it is preferable to use an excess of the second solid raw material so that the entire first organic raw material can be utilized. The mass ratio of the first organic raw material to the second solid raw material is preferably 1:1 to 1:10, more preferably 1:1 to 1:5. The solid-containing mixture in the solid state includes the solid mixture described below.

[0043] <Solid mixture> In a method for producing hydrogen according to one embodiment of the present invention, hydrogen is generated from a solid mixture obtained by mixing a first solid raw material and a second solid raw material. The solid mixture can be prepared, for example, by putting the first solid raw material and the second solid raw material into an appropriate reaction vessel and mixing the two raw materials in the reaction vessel until they are in sufficient contact with each other. The mass ratio of the first solid raw material to the second solid raw material in the solid mixture can be appropriately selected depending on the type and shape of the plant biomass constituting the first solid raw material, the type of microorganism from which the first solid raw material is derived, the type of compound contained in the first solid raw material, and the like. From the viewpoint of hydrogen production efficiency, it is preferable to use an excess of the second solid raw material so that the entire first solid raw material can be utilized. The mass ratio of the first solid raw material to the second solid raw material is preferably 1:1 to 1:10, more preferably 1:1 to 1:5.

[0044] <Reaction conditions> In a method for producing hydrogen according to one aspect of the present invention, the solid-containing mixture or solid-state mixture is held at a predetermined temperature to generate hydrogen. The predetermined temperature is usually 20 to 300°C (20°C or higher and 300°C or lower), preferably 20 to 250°C, and more preferably 25 to 250°C. The upper limit temperature may be 200°C, 150°C, or 100°C. The lower limit temperature may be 40°C, 50°C, or 75°C. In this aspect, the predetermined temperature is set to 300°C or lower, so that there is no risk of the solid-containing mixture or solid-state mixture burning even in an atmosphere containing oxygen.

[0045] The time for which the solid-containing mixture or solid-state mixture is held at a predetermined temperature is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more.

[0046] In a preferred embodiment, the solid-containing mixture or solid-state mixture is maintained at the predetermined temperature while being stirred. Stirring increases the contact opportunity between the first organic raw material or the first solid raw material and the second solid raw material, improving the efficiency of hydrogen production. There is no particular limitation on the method of stirring, and for example, stirring means such as a stirrer or agitator blades may be used, or the solid-containing mixture or solid-state mixture itself may be stirred by shaking, turning upside down, rotating, etc.

[0047] The time for which the solid-containing mixture or solid-state mixture is held at the specified temperature may be appropriately selected depending on the type and shape of the organic compound constituting the first organic raw material, the type and shape of the plant biomass constituting the first solid raw material, the mass and mass ratio of the first organic raw material or the first solid raw material and the second solid raw material, the total mass of the solid-containing mixture or solid-state mixture, the stirring conditions, etc., but it is preferable to hold the temperature for at least 1 minute.

[0048] The atmosphere in which the hydrogen production method according to one embodiment of the present invention is carried out is not particularly limited, and may be either an atmosphere containing oxygen (e.g., an air atmosphere) or an atmosphere not containing oxygen (e.g., an inert atmosphere). In a preferred embodiment, the method is carried out in an atmosphere containing 15% by volume or more of oxygen, for example, an air atmosphere. According to this embodiment, there is no need to replace the atmosphere with an inert gas, making the operation easier.

[0049] In another preferred embodiment, the reaction is carried out in an atmosphere containing 15% by volume or more of carbon dioxide. The carbon dioxide concentration is preferably 25% by volume or more, more preferably 30% by volume or more, even more preferably 50% by volume or more, even more preferably 60% by volume or more, even more preferably 75% by volume or more, even more preferably 90% by volume or more. By carrying out the reaction in an atmosphere containing a large amount of carbon dioxide, higher hydrogen productivity can be obtained.

[0050] The gases generated by maintaining the solid-containing mixture or the solid-state mixture at a predetermined temperature are hydrogen, carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4). Of these, carbon dioxide is absorbed by the alkali metal hydroxide contained in the solid-containing mixture or the solid-state mixture. Therefore, in this embodiment, a process for separating hydrogen and carbon dioxide is basically unnecessary. This is also true when the reaction is carried out under an atmosphere containing carbon dioxide.

[0051] <Hydrogen production system> A hydrogen production system according to one embodiment of the present invention includes a reaction vessel capable of containing a solid-containing material or a solid material and maintaining the predetermined temperature, and the solid-containing mixture or solid-state mixture is contained in the reaction vessel. The volume of the reaction vessel is not particularly limited, and may be, for example, about 10 to 1000 mL, about 1 to 10 L, about 10 to 100 L, or about 100 to 1000 L. The material of the reaction vessel is not particularly limited, and may be appropriately selected depending on the volume, etc. For example, a vessel made of glass, resin, or metal may be selected.

[0052] The amount of the solid-containing mixture or solid-state mixture to be contained is not particularly limited, but may be, for example, about 30 to 50% of the volume of the reaction vessel.

[0053] In the hydrogen production system of this embodiment, it is preferable that the reaction vessel has a stirring function for stirring the contents. For example, a vessel equipped with stirring blades can be used as the reaction vessel. In addition, the reaction vessel itself may be equipped with a mechanism for shaking, turning upside down, rotating, etc.

[0054] The hydrogen production system of this embodiment may further include a hydrogen isolation and purification means for isolating and purifying the generated hydrogen. For example, the system may further include a device for separating hydrogen from the by-products carbon monoxide and methane.

[0055] The hydrogen production system of this embodiment may be equipped with a mechanism capable of continuously introducing the first organic feedstock, the first solid feedstock and / or the second solid feedstock into the reaction vessel. EXAMPLES

[0056] 1. Raw materials The raw materials shown in Tables 1 to 3 were used. Specifically, cedar wood flour, sodium lignin sulfonate, glucose, or cellulose (Avicel (registered trademark)) was used as the first solid raw material (Tables 1 and 3). Glycolic acid, sodium 2-hydroxybutanoate, erythritol, etc. were used as the first organic raw material (Table 2). Granular sodium hydroxide or potassium hydroxide was used as the second solid raw material.

[0057] 2. Preparation of solid-containing or solid-like mixtures and hydrogen production In a 20 mL headspace vial, the first organic raw material or the first solid raw material in the amounts shown in Tables 1 to 3, 300 mg or 600 mg of the second solid raw material, and a stirrer were placed, and the vial was sealed with a septum cap. After sealing, two injection needles were inserted, and a gas having a desired composition was pumped from one needle for about 30 seconds to replace the air in the vial, and then the two injection needles were quickly pulled out. As a result, the gas phase in the vial was replaced with the desired gas. The vial was heated at a predetermined reaction temperature for 1 hour while stirring using a heating device. The reaction temperature was 25°C, 120°C, 200°C, or 250°C. After heating, 1 mL of the gas phase in the vial was collected with a gas-tight syringe, and gas chromatography (GC) analysis was performed under the following conditions.

[0058] The volume of hydrogen evolved was calculated using the external calibration curve method according to the following formula (1). The volumes of CO evolved and CH4 evolved were also calculated in the same manner.

[0059] Formula (1): Volume of hydrogen generated (mL) = Volume of hydrogen in collected gas phase (mL / mL) x 20 (mL)

[0060] The hydrogen purity (%) was calculated using the following formula (2-1) (Experimental Examples 1 to 28) or formula (2-2) (Experimental Examples 29 to 36).

[0061] Formula (2-1): Hydrogen purity (%) = hydrogen volume (mL) / (hydrogen volume (mL) + CO volume (mL) + CH4 volume (mL)) x 100

[0062] Mathematical formula (2-2): Hydrogen purity (%) = Hydrogen volume (mL) / (Hydrogen volume (mL) + CO volume (mL) + CH4 volume (mL) + CO2 volume (mL)) × 100

[0063] <GC analysis conditions> · Detector: Thermal conductivity detector (TCD) · Column: shin carbon st 50 / 80 (2m) · Carrier gas: Argon · Detector temperature: 250 °C · Vaporization chamber temperature: 200 °C · Flow rate: 50 mL / min · Time program: 40 °C (3 minutes) → (Heating at 20 °C / min) → 200 °C (0 minutes)

[0064] 3. Results The raw materials used in each experimental example, their usage amounts, and the measurement results are shown in Tables 1 to 3. In the tables, argon is denoted as Ar, oxygen as O2, and carbon dioxide as CO2. In the case of a mixed gas, the composition (%) is also shown.

[0065] <Experimental Examples 1 to 13> In Experimental Examples 1 to 5 where sugi wood powder was used as the first raw material (first solid raw material) and sodium hydroxide was used as the second solid raw material, high-purity hydrogen was generated at a reaction temperature of 25 °C to 250 °C in both an oxygen atmosphere and an argon atmosphere. The higher the reaction temperature, the higher the hydrogen generation amount, but it was also possible to generate hydrogen even at 25 °C.

[0066] In Experimental Examples 6 to 11 where sodium lignosulfonate, cellulose, or glucose was used as the first raw material (first solid raw material) and sodium hydroxide was used as the second solid raw material, high-purity hydrogen was generated at a reaction temperature of 120 °C in both an oxygen atmosphere and an argon atmosphere.

[0067] In Experimental Examples 12 and 13 where sugi wood powder was used as the first raw material (first solid raw material) and potassium hydroxide was used as the second solid raw material, high-purity hydrogen was generated at a reaction temperature of 120 °C in both an oxygen atmosphere and an argon atmosphere.

[0068] In addition, in Experimental Examples 1 to 13, no carbon dioxide was detected in the final product.

[0069] <Experimental Examples 14-28> In Experimental Examples 14 to 28, various solid or liquid organic compounds were used as the first raw material. The reaction temperature was 120°C. As a result, in the case of any organic compound, high purity hydrogen was generated in an oxygen atmosphere or an argon atmosphere. Note that, among the first raw materials in Experimental Examples 14 to 28, none of the liquid ones dissolve sodium hydroxide.

[0070] In addition, in Experimental Examples 14 to 28, carbon dioxide was not detected in the final product.

[0071] <Experimental Examples 29-36> In Experimental Examples 29 to 36, the atmosphere containing oxygen and / or carbon dioxide was mainly examined. The amount of the second solid raw material (sodium hydroxide) used was 600 mg. The reaction temperature was 120°C.

[0072] As shown in Experimental Examples 29 to 31, the higher the oxygen concentration in the atmosphere, the higher the hydrogen productivity. That is, the hydrogen productivity improved depending on the oxygen concentration.

[0073] When a mixed gas of argon and carbon dioxide was used as in Experimental Examples 32 to 36, the higher the carbon dioxide concentration in the atmosphere, the higher the hydrogen productivity. In other words, the hydrogen productivity improved depending on the carbon dioxide concentration. Furthermore, in Experimental Examples 32 to 36, the hydrogen purity was 100%, and high-purity hydrogen was stably obtained.

[0074] Comparing Experimental Examples 30 and 34, the use of a mixed gas of oxygen and carbon dioxide (50:50) resulted in higher hydrogen productivity than the use of a mixed gas of argon and carbon dioxide (50:50).

[0075] In addition, in Experimental Examples 30 and 33 to 35, in which the reaction was carried out in an atmosphere containing carbon dioxide, carbon dioxide was not detected in the final product. This was thought to be because all of the carbon dioxide was ultimately absorbed by the solid sodium hydroxide.

[0076] As described above, it was found that hydrogen productivity can be improved by carrying out the reaction in an atmosphere containing a predetermined amount of oxygen and / or carbon dioxide. Furthermore, it was found that high-purity hydrogen can be stably obtained by carrying out the reaction in an atmosphere containing carbon dioxide.

[0077] [Table 1]

[0078] [Table 2]

[0079] [Table 3]

Claims

1. A method for producing hydrogen, comprising: mixing a first organic raw material, which is a solid or liquid made of an organic compound, with a second solid raw material, which is a solid alkali metal hydroxide; maintaining a solid-containing mixture at a predetermined temperature of 20°C to 300°C; and generating hydrogen from the solid-containing mixture.

2. A method for producing hydrogen, comprising: mixing a first solid raw material derived from a plant biomass or a microorganism with a second solid raw material comprising a solid alkali metal hydroxide; maintaining the resulting solid mixture at a predetermined temperature of 20°C to 300°C; and generating hydrogen from the solid mixture.

3. 3. The method for producing hydrogen according to claim 2, wherein the first solid feedstock is derived from woody biomass.

4. 3. The method for producing hydrogen according to claim 2, wherein the first solid raw material is at least one selected from the group consisting of wood chips, wood chips, wood waste, wood flour, cellulose, lignosulfonic acid or a salt thereof, and glucose.

5. 3. The method for producing hydrogen according to claim 1 or 2, wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide.

6. 3. The method for producing hydrogen according to claim 1 or 2, wherein the solid-containing mixture or the solid-state mixture is maintained at the predetermined temperature for one minute or more.

7. 3. The method for producing hydrogen according to claim 1 or 2, wherein the solid-containing mixture or the solid-state mixture is maintained at the predetermined temperature while being stirred.

8. 3. The method for producing hydrogen according to claim 1 or 2, which is carried out in an atmosphere containing 15 volume % or more of oxygen.

9. 3. The method for producing hydrogen according to claim 1 or 2, which is carried out in an atmosphere containing 15 volume % or more of carbon dioxide.

10. The first solid material is derived from woody biomass, The alkali metal hydroxide is sodium hydroxide or potassium hydroxide; The solid mixture is stirred while being held at the predetermined temperature for at least 1 minute, The method for producing hydrogen according to claim 2 , which is carried out in an atmosphere containing 15% by volume or more of oxygen.

11. The first solid material is derived from woody biomass, The alkali metal hydroxide is sodium hydroxide or potassium hydroxide; The solid mixture is stirred while being held at the predetermined temperature for at least 1 minute, The method for producing hydrogen according to claim 2 , which is carried out in an atmosphere containing 15% by volume or more of carbon dioxide.

12. A hydrogen production system used in the hydrogen production method according to any one of claims 1 to 4, A reaction vessel capable of containing a solid-containing material or a solid material and maintaining the predetermined temperature is provided, A hydrogen production system, wherein the solid-containing mixture or the solid-state mixture is contained within the reaction vessel.

13. The hydrogen production system of claim 12 , wherein the solid-containing mixture or the solid-state mixture is capable of being maintained at the predetermined temperature in the reaction vessel.

14. The hydrogen production system of claim 12 , wherein the solid-containing mixture or the solid-like mixture is capable of being agitated in the reaction vessel.

15. The hydrogen production system according to claim 12 , further comprising a hydrogen isolation and purification means for isolating and purifying hydrogen generated from the solid-containing mixture or the solid-state mixture.

Images