JP2018118877A - Hydrogen supply system and hydrogen supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen supply system which generates formic acid by effectively utilizing sunlight energy, stores the formic acid, converts the stored formic acid to hydrogen, and safely and efficiently supplies the hydrogen as energy source.SOLUTION: A hydrogen supply system of the present invention generates formic acid by artificial photosynthesis using carbon dioxide in the atmosphere or exhaust carbon dioxide in a formic acid generation apparatus 50, stores the formic acid, recycles carbon dioxide generated by decomposing formic acid, by supplying the carbon dioxide to the formic acid generation apparatus 50, the formic acid being supplied from the formic acid generation apparatus 50, the carbon dioxide being generated in a formic acid decomposition apparatus 60 which decomposes formic acid into hydrogen and carbon dioxide by a catalytic reaction under the environment of oxygen free at normal temperature under normal pressure, and supplies the hydrogen gas generated by decomposing the formic acid to an external apparatus.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydrogen supply system and a hydrogen supply method using solar energy.

  Until now, fossil fuels such as coal and oil have been widely used as energy. However, in recent years, there are problems such as depletion of resources and global warming due to carbon dioxide. Hydrogen energy has attracted attention as an alternative energy. ing.

  Moreover, utilization of solar energy is mentioned as a representative of clean energy.

  In recent years, water is electrolyzed with electricity generated by solar power generation, etc. to extract hydrogen, and development of fuel cells and hydrogen engines using the hydrogen as fuel resources, hydrogen fuel cell vehicles and hydrogen engine vehicles equipped with these, etc. Technical development is underway.

  In recent years, fuel cell power generation systems that generate power using hydrogen have been rapidly developed as a power source for various uses such as automobiles, household power generation facilities, vending machines, and portable devices (see, for example, Patent Document 1). ).

  Since hydrogen produces only water when combusted, it is more environmentally friendly in that it does not involve the emission of carbon dioxide, and it has great expectations as a future energy source.

  However, since hydrogen is a highly reactive gas, it is difficult to transport and store, and safe and low-cost transport and storage technology is required for its stable supply.

  As a method for storing hydrogen, a method of storing in a cylinder or the like as a high-pressure gas is generally used. However, this method has problems such as safety during high-pressure gas transportation and hydrogen embrittlement of the container. For example, in order to carry hydrogen with low energy density as fuel for automobiles, high pressures of several hundred atmospheres must be applied. In addition, there is a method of storing hydrogen gas in the form of liquid hydrogen, but it is not common because it needs to be at a very low temperature. In addition, when the production of hydrogen is considered on an industrial scale, since it is usually produced by electrolyzing water, there is a problem in production cost.

  Conventionally, as a hydrogen storage method, it has been proposed to use formic acid (HCOOH) as a hydrogen storage tank and to extract hydrogen from formic acid when necessary (see, for example, Patent Documents 2 and 3).

  As a method for producing formic acid, for example, a method for producing formic acid in the presence of a catalyst while maintaining hydrogen gas and carbon dioxide gas at a temperature of 20 to 250 ° C. and a pressure of 2 to 35 MPa has been proposed (for example, Patent Document 4). reference). In the method described in Patent Document 4, high temperature and high pressure are required, or large-scale equipment is required.

  Therefore, an artificial photosynthesis method has been studied in which water is decomposed by light energy and formic acid is generated from carbon dioxide and water by an enzyme or the like using the obtained electrons.

  Also proposed is a method for converting carbon dioxide into formic acid, characterized in that an enzymatic reaction catalyzed by formate dehydrogenase in the presence of carbon dioxide is carried out using a viologen compound or a bipyridinium salt derivative as an electron carrier. (For example, refer to Patent Document 5). In order to produce formic acid by the method described in Patent Document 5, a photosensitizer, an electron carrier, and a catalyst are required.

  As a method for decomposing formic acid, there is thermal decomposition. However, simply heating formic acid and decomposing it requires a high temperature higher than the boiling point of formic acid (about 101 ° C), so it is not always possible to maintain a high temperature state. There is a problem in terms of cost.

  There is also a method of decomposing formic acid using a catalyst, for example, a rhodium mononuclear metal complex having a ligand composed of a cyclopentadiene-substituted product and a ligand composed of a nitrogen-containing heterocyclic compound, its tautomer or A catalyst for formic acid decomposition containing a stereoisomer or a salt thereof, or a catalyst for formic acid decomposition containing a binuclear metal complex, a tautomer or stereoisomer thereof, or a salt thereof has been proposed (for example, Patent Documents). 6 and 7).

  However, a catalyst having a complicated structural formula as described in Patent Document 6 and Patent Document 7 has a problem that it is difficult to synthesize.

  In addition, a formic acid decomposition method is proposed in which formic acid is reacted with oxygen or oxygen-containing gas in the presence of a formic acid decomposition catalyst to decompose formic acid into water and carbon dioxide (for example, patents). Reference 8).

  Thus, when formic acid is decomposed in the presence of oxygen, water and carbon dioxide are produced, and hydrogen is not generated. Therefore, when hydrogen is used as an energy source by decomposing formic acid, such a reaction becomes a side reaction and is not desirable.

JP 2007-224281 A JP 2013-32271 A JP 2013-193983 A Japanese Patent Laid-Open No. 2001-192676 International Publication No. 2013/187485 JP 2009-78200 A International Publication No. 2008/059630 Japanese Patent Laying-Open No. 2015-66515

Formic acid (HCOOH) is a liquid at room temperature, can be interconverted with hydrogen (H ₂ ) / carbon dioxide (CO ₂ ), and has a high energy density.

  Formic acid has a hydrogen storage capacity of 4.4% at room temperature and normal pressure, and its energy change accompanying the interconversion with carbon dioxide is small, so it can be used in mild conditions and is expected to be an efficient hydride for hydrogen storage. Has been.

  In order to produce formic acid as a fuel source by the method described in Patent Document 5 using sunlight, a photosensitizer, an electron carrier, and a catalyst are required.

  However, by using sunlight and water as energy sources and electron sources respectively, natural leaves are converted from carbon dioxide to organic matter and oxygen as usual, at normal temperature, normal pressure, and oxygen atmosphere. When the substance conversion reaction is artificially performed in an oxygen atmosphere at normal temperature and normal pressure, there is a problem that the reaction is inhibited by oxygen.

  Generally, since this reaction is inhibited by oxygen, it is necessary to remove oxygen. However, the cost of oxygen removal is one big problem for realizing artificial photosynthesis.

  Further, as described above, when formic acid is decomposed using a catalyst, it is preferable that the reaction system is simple in consideration of versatility. Further, in order to efficiently convert formic acid into hydrogen, it is desirable that no side reaction occurs in which water and carbon dioxide are generated from formic acid.

  Accordingly, an object of the present invention is to realize a practical residential energy supply system in view of the conventional situation as described above. Formic acid is generated and stored by effectively using solar energy. An object of the present invention is to provide a hydrogen supply system and a hydrogen supply method for converting stored formic acid into hydrogen and supplying it safely and efficiently as an energy source.

  Other objects of the present invention and specific advantages obtained by the present invention will become more apparent from the description of embodiments described below.

  The present invention is a hydrogen supply system, a formic acid generator for generating formic acid from water and air or exhaust carbon dioxide by artificial photosynthesis, a formic acid storage tank for storing formic acid generated by the formic acid generator, Formic acid supplied from a formic acid storage tank consists of a formic acid decomposition device that decomposes into hydrogen and carbon dioxide by catalytic reaction in a deoxygenated environment at normal temperature and normal pressure. The formic acid decomposition device is supplied from the formic acid generation device. The hydrogen obtained by decomposing the formic acid is supplied to an external device.

  In the hydrogen supply system according to the present invention, the formic acid generator is obtained by decomposing water to generate oxygen, hydrogen ion generation means for obtaining hydrogen ions and electrons, and decomposition of water by the hydrogen ion generation means. Formic acid generating means for generating formic acid by artificial photosynthesis from carbon dioxide in the atmosphere and / or exhausted carbon dioxide using a formic acid generating device using the hydrogen ions and electrons generated can be provided.

  Further, in the hydrogen supply system according to the present invention, the formic acid generating device is, for example, one in which a dye, methyl viologen, and formate dehydrogenase are supported on a porous layer made of aluminum oxide fine particles formed on the surface of a substrate. can do.

  Further, in the hydrogen supply system according to the present invention, the formic acid decomposition apparatus is configured to, for example, convert formic acid into hydrogen in a deoxygenated environment at room temperature and atmospheric pressure using a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone. And can be decomposed into carbon dioxide.

  Moreover, the hydrogen supply system which concerns on this invention WHEREIN: The thickness of the said porous layer shall be 1-10 micrometers.

  Further, in the hydrogen supply system according to the present invention, the formic acid decomposition apparatus is a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinyl pyrrolidone. It can be decomposed to carbon.

  In the hydrogen supply system according to the present invention, the platinum fine particles may have a particle diameter of 1 nm to 50 nm.

  Moreover, the hydrogen supply system which concerns on this invention WHEREIN: The addition amount of the said water-soluble polymer polyvinylpyrrolidone shall be 1 mass% or more and 20 mass% or less with respect to the said platinum microparticles.

  In the hydrogen supply system according to the present invention, the formic acid decomposition apparatus includes, for example, a storage unit that stores at least formic acid, a reaction unit that decomposes formic acid supplied from the storage unit into hydrogen and carbon dioxide, and the reaction. A separation part for separating hydrogen and carbon dioxide produced in the part, and a control part for controlling the reaction part under deoxygenation at normal temperature and normal pressure, wherein the reaction part converts the platinum fine particles into water-soluble polymer polyvinyl It can have a catalyst dispersed by pyrrolidone.

  In the hydrogen supply system according to the present invention, the formic acid decomposition apparatus circulates carbon dioxide by supplying carbon dioxide obtained by decomposing formic acid supplied from the formic acid storage tank to the formic acid generation apparatus. In addition, hydrogen can be supplied to an external device by decomposing formic acid.

  Furthermore, in the hydrogen supply system according to the present invention, the external device may be a residential hydrogen power generation device.

  The present invention is a method for supplying hydrogen, which uses hydrogen ions / electrons obtained by photolysis of water into oxygen to form a porous layer of aluminum oxide fine particles formed on the surface of a solid substrate with a dye, methyl viologen, By using a formic acid generating device carrying formate dehydrogenase, the hydrogen ion. In a deoxygenated environment at normal temperature and pressure, using a formic acid production process that produces and stores formic acid from electrons and atmospheric or exhaust carbon dioxide by artificial photosynthesis and a catalyst in which platinum fine particles are dispersed with water-soluble polymer polyvinylpyrrolidone. A formic acid decomposition step of decomposing formic acid into hydrogen and carbon dioxide, and in the formic acid decomposition step, carbon dioxide obtained by decomposing the formic acid stored in the formic acid generation step is supplied to the formic acid generation step. And formic acid is decomposed to supply hydrogen to an external device.

  In the hydrogen supply system according to the present invention, in a formic acid generator, formic acid is generated and stored by artificial photosynthesis from atmospheric or exhaust carbon dioxide, and the stored formic acid is catalyzed in a deoxygenated environment at normal temperature and normal pressure. The carbon dioxide obtained by decomposing the formic acid supplied from the formic acid generator by the formic acid decomposer that decomposes into hydrogen and carbon dioxide is supplied to the formic acid generator and circulated, so that carbon dioxide is released to the outside. It is possible to effectively and efficiently supply hydrogen obtained by decomposing formic acid by the formic acid decomposition apparatus to an external apparatus as an energy source.

  In the formic acid generator in the hydrogen supply system according to the present invention, hydrogen ions and electrons generated by the decomposition of water and carbon dioxide discharged from the air and / or other engines can be used effectively, and oxidation can be performed. By forming a porous layer with aluminum fine particles, it is possible to efficiently achieve electron transfer to methyl viologen without depriving the excitation energy of the dye molecule, and it is possible to convert the hydrogen source into formic acid and store it. it can.

  In the formic acid decomposition apparatus in the hydrogen supply system according to the present invention, platinum fine particles are dispersed with the water-soluble polymer polyvinyl pyrrolidone, thereby efficiently generating hydrogen from formic acid without causing side reactions that generate water and carbon dioxide. can do.

  Therefore, according to the present invention, it is possible to provide a hydrogen supply system and a hydrogen supply method that use solar energy effectively and supply hydrogen safely and efficiently as an energy source, and use hydrogen as an energy source. A realistic residential energy supply system can be realized.

It is a block diagram which shows the structural example of the hydrogen supply system which implements this invention. It is a schematic diagram showing the structural example of the formic acid production | generation apparatus in the said hydrogen supply system. It is a schematic diagram which shows the structural example of the formic acid production | generation device with which the said formic acid production | generation apparatus is equipped. It is a schematic diagram which shows reaction in the said formic acid production | generation device. It is a flowchart which shows the outline of the preparation methods of the said formic acid production | generation device. It is a schematic diagram which shows each process of the preparation method of the said formic acid production | generation device, (A) is an application | coating process, (B) is a drying process, (C) is a heat processing process, (D) shows a support process. It is a schematic diagram showing the structural example of the formic acid decomposition | disassembly apparatus in the said hydrogen supply system. It is process drawing which shows the execution process of the hydrogen supply method performed with the said hydrogen supply system. It is a perspective view which shows an example of the energy supply system for houses to which this invention is applied.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Needless to say, the present invention is not limited to the following examples, and can be arbitrarily changed without departing from the gist of the present invention.

  The present invention is implemented, for example, by a hydrogen supply system 100 configured as shown in FIG.

  The hydrogen supply system 100 includes a formic acid generation device 50 by artificial photosynthesis, a formic acid storage tank 55 for storing formic acid generated by the formic acid generation device 50, and formic acid supplied from the formic acid storage tank 55 with hydrogen and carbon dioxide. It comprises a formic acid decomposition apparatus 60 that decomposes into

  The formic acid generator 50 generates formic acid from water and air or exhausted carbon dioxide by artificial photosynthesis and stores it in the storage tank 55.

  The formic acid decomposition apparatus 60 decomposes formic acid into hydrogen and carbon dioxide by a catalytic reaction in a deoxygenated environment at normal temperature and normal pressure, and formic acid supplied from the storage tank 55 via the flow path 40 is used. Hydrogen obtained by decomposition is supplied to an external device.

  In the energy supply system 100, the formic acid storage tank 55 has a stationary structure in which the formic acid generation device 50 and the formic acid decomposition device 60 are simultaneously connected via the flow path 40. It is not necessary to be connected to the decomposition apparatus 60 at the same time, and it is possible to adopt a cut ridge type structure that is detachably connected to the formic acid generation apparatus 50 and the formic acid decomposition apparatus 60 individually.

  In the energy supply system 100, carbon dioxide obtained by decomposing formic acid supplied from the storage tank 55 via the flow path 40 by the formic acid decomposition apparatus 60 is passed to the formic acid generation apparatus 50 via the flow path 70. The hydrogen obtained by decomposing formic acid is supplied to an external device.

  Formic acid generator 50 in hydrogen supply system 100 includes, for example, as shown in FIG. 2, hydrogen ion generating means 20 that decomposes water to obtain hydrogen ions and electrons, and artificial photosynthesis from hydrogen ions, electrons, and carbon dioxide. The formic acid production | generation means 30 using the formic acid production | generation device 10 which produces | generates formic acid by this is provided.

  In this formic acid generating device 50, the hydrogen ion generating means 20 and the formic acid generating means 30 are installed, for example, in a water tank partitioned by a semipermeable membrane that selectively permeates hydrogen ions, and the hydrogen ion generating means 20 The formic acid generating means 30 is connected by a conducting wire, and hydrogen ions and electrons generated by the hydrogen ion generating means 20 are sent to the formic acid generating means 30.

The formic acid generation means 30 uses artificial hydrogen gas and / or exhaust carbon dioxide in the atmosphere by the formic acid generation device 10 using hydrogen ions and electrons obtained by decomposing water by the hydrogen ion generation means 20. Produces formic acid.

  The formic acid generating device 10 used in the formic acid generating means 30 includes, for example, a substrate 11, aluminum oxide fine particles 12, a dye 13, methyl viologen 14, and a formate dehydrogenase 15 as shown in FIG. .

  First, each structure of the formic acid production | generation device 10 is demonstrated.

  The substrate 11 is a solid substrate on which a porous layer made of aluminum oxide fine particles 12 is formed, and the dye 13, methyl viologen 14 and formate dehydrogenase 15 are supported on the porous layer. The material of the substrate is not particularly limited, but a metal substrate such as aluminum or a glass substrate is used. For example, non-fluorescent glass is preferable.

  The aluminum oxide fine particles 12 form a porous layer on the substrate 11. As will be described later, the aluminum oxide fine particles 12 are heated together with polymer beads such as polystyrene beads, whereby only the aluminum oxide fine particles 12 remain and form a porous layer. The thickness of the porous layer is preferably 1 to 10 μm. If the thickness is less than 1 μm, the thickness is not sufficient to support the dye 13, methyl viologen 14 and formate dehydrogenase 15, and if the thickness exceeds 10 μm, the enzyme or the like supported inside does not work sufficiently. .

  Since the porous layer made of the aluminum oxide fine particles 12 is an insulator and does not deprive the excitation energy of the dye molecules as compared with the conventional porous layer made of silica gel or the like, the electron transfer to the methyl viologen 14 efficiently. The benefits that can be achieved are created.

  The dye 13 is a photosensitizer that plays a role of assisting a reaction or a light emitting process by passing light energy obtained by absorption of the dye 13 to another substance. That is, the dye 13 has a function (photoelectric conversion ability) that absorbs light energy in the reaction system irradiated with light, converts the light energy into electron energy, and transfers electrons to the electron transporter (coenzyme). It is. Examples of the dye 13 include porphyrin derivatives, ruthenium bipyridine complex derivatives, and pyrene derivatives. For example, N197 dye, tetrakis (4-methylpyridyl) porphyrin zinc (ZnTMPyP), tetraphenylporphyrin tetrasulfonate zinc (ZnTPPS). ), Ruthenium trisbipyridine, chlorophyll, and the like.

  Methyl viologen (MV) 14 is an artificial coenzyme having an electron transport function that receives electrons from the dye 13 and passes the electrons to other substances. That is, the methyl viologen 14 has a reducing function of receiving electrons from the dye 13 photoexcited by light irradiation and passing the electrons to the enzyme.

  The enzyme 15 is a substance that accelerates the reaction rate of a specific chemical reaction, and is a substance that does not change before and after the reaction. The enzyme 15 receives electrons from the electron transporter in the reaction system irradiated with light, and reduces the raw material to generate a product. In the formic acid generating device 10, formate dehydrogenase (formate dehydrogenase, FDH) is used as the enzyme 15, the raw materials are hydrogen ions and carbon dioxide, and the generated material is formic acid. The formic acid production device 10 uses formate dehydrogenase because it is intended to produce formic acid, but aldehyde dehydrogenase and alcohol dehydrogenase are used in the methanol production reaction, and malate dehydrogenase (decarboxylation is used in the malate production reaction. It is also possible to apply to a production device using other enzymes such as

  In addition, the said formic acid production | generation device 10 may contain the electron donor. The electron donor has a function of passing electrons to other substances and a reduction function, and is itself oxidized. That is, the electron donor means one having a function of transferring electrons to the dye 13 that has lost electrons and a reduction function in the reaction system irradiated with light. Examples of the electron donor include triethanolamine, ethylenediamine, ethylenediaminetetraacetate, ethylenediamine hydrochloride, triethylamine, mercaptoethanol, and the like.

  As described above, in this formic acid generating apparatus 50, the formic acid generating device 10 for generating formic acid from hydrogen ions, electrons, and carbon dioxide by artificial photosynthesis is porous with aluminum oxide fine particles 12 formed on the surface of the substrate 11. A dye layer 13, methyl viologen 14 and formate dehydrogenase 15 are supported on the layer.

  As described above, in the formic acid generating device 10, since the aluminum oxide fine particles 12 do not deprive the excitation energy of the dye molecules by forming the porous layer with the aluminum oxide fine particles 12, the methyl viologen 14 is efficiently absorbed. Electron transfer can be achieved and the hydrogen source can be converted to formic acid and stored in the formic acid storage tank 55.

  According to the formic acid generating apparatus 50 having such a configuration, the formic acid generating device 10 effectively uses hydrogen ions and electrons generated by the decomposition of water and carbon dioxide discharged from the air and / or other engines. In addition, by forming a porous layer with the aluminum oxide fine particles 12, electron transfer to the methyl viologen 14 can be efficiently achieved without depriving the excitation energy of the dye molecules, and the hydrogen source can be converted to formic acid. Can be stored in the formic acid storage tank 55.

  That is, the formic acid generating device 50 in this energy supply system 100 is porous by hydrogen ion generating means 20 that decomposes water to generate oxygen and acquire hydrogen ions and electrons, and aluminum oxide fine particles 12 formed on the surface of the solid substrate. When formic acid is generated from hydrogen ions, electrons and carbon dioxide by artificial photosynthesis using a formic acid generating device 10 in which a layer 13 carries a dye 13, methyl viologen 14 and formate dehydrogenase 15, the formic acid generating means 30 is provided. By using hydrogen ions and electrons obtained by photolyzing water into oxygen by the ion generating means 20, the formic acid generating means 30 generates formic acid from the atmospheric or exhaust carbon dioxide by artificial photosynthesis by the formic acid generating device 10. It is generated and stored in the formic acid storage tank 55.

  In the hydrogen supply system 100, the formic acid generating device 50 is used as a photochemical reaction device. In use, it is preferable that the formic acid generating device 10 in the formic acid generating means 30 is irradiated with light. As the light source for irradiating the formic acid generating device 10 with light, the sun, an artificial light source or the like can be used.

  Next, a photochemical reaction method in the formic acid generator 50 will be described.

In the formic acid generating apparatus 50, first, the hydrogen ion generating means 20 decomposes water to generate oxygen, hydrogen ions, and electrons as shown in the following equation (1).
2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ (1)

  The hydrogen ion generating means 20 is not particularly limited as long as the above reaction occurs. For example, a water splitting device such as a substrate carrying a photocatalyst is used.

Here, a schematic diagram showing the reaction in the formic acid generating device 10 is shown in FIG. For example, by irradiating light in the presence of an electron donor, the dye is excited, the electron (e ⁻ ) moves from the excited dye to methyl viologen (MV ²⁺ ), and the methyl viologen that has received the electron is Reduced to produce reduced methyl viologen (MV ⁺ ). Reduced methyl viologen (MV ⁺ ) supplies electrons to formate dehydrogenase (FDH). As a result, an enzymatic reaction proceeds, and formic acid is generated from hydrogen ions, electrons, and carbon dioxide.

In the formic acid generation means 30, the formic acid generation device 10 generates formic acid from hydrogen ions, electrons, and carbon dioxide through the photoreaction (artificial photosynthesis) process shown in FIG. 4 (the following formula (2)). At this time, hydrogen ions and electrons generated by the hydrogen ion generation means 20 are consumed. Moreover, what exists in the air | atmosphere and / or in the waste gas from another engine can be utilized for carbon dioxide.
CO ₂ + 2H ⁺ + 2e ⁻ → HCOOH (2)

  In this energy supply system 100, the formic acid produced by the formic acid production device 50 and stored in the formic acid storage tank 55 is decomposed by formic acid via the flow path 40, for example, at night when sunlight cannot be obtained and artificial photosynthesis cannot be performed. It is sent to the apparatus 60 and decomposed by the formic acid decomposition apparatus 60 to be consumed and generated by an engine that can generate and use hydrogen.

  The formic acid generating device 10 used for the formic acid generating means 30 is produced through, for example, a coating step S1, a drying step S2, a heat treatment step S3, and a supporting step S4 as shown in FIGS. The

  FIG. 5 is a flowchart showing an outline of a method for producing the formic acid generating device 10, and FIG. 6 is a schematic diagram showing each step of the method for producing the formic acid producing device 10.

  Hereinafter, each process S1-S4 for producing the formic acid production | generation device 10 is demonstrated.

  In the application step S1, a mixed solution of aluminum oxide fine particles 12 and polymer beads 22 is applied to the substrate 11 (FIG. 6A). As the substrate 11, for example, non-fluorescent glass is used. As a mixed solution, polymer beads 22 are dispersed and mixed in an ethanol slurry containing aluminum oxide fine particles 12. The particle diameter of the aluminum oxide fine particles 12 is preferably 20 to 50 nm, and the particle diameter of the polymer beads 22 is preferably 50 to 100 nm. The polymer beads 22 are desirably those that can be burned off in the subsequent heat treatment step S3. For example, polystyrene beads are preferable.

  The mixing ratio of the aluminum oxide fine particles and the polymer beads in the mixed solution is preferably 10: 1 by mass ratio.

  In the drying step S2, the substrate 11 coated with the mixed solution is dried (FIG. 6B). As a result, ethanol as a solvent in the ethanol slurry is evaporated, and a mixture of the aluminum oxide fine particles 12 and the polymer beads 22 remains on the substrate 11.

  In the heat treatment step S3, the substrate 11 is heated to burn off the polymer beads 22, and a porous layer made of the aluminum oxide fine particles 12 is formed on the surface of the substrate 11 (FIG. 6C). The heating temperature only needs to be a temperature at which the polymer beads 22 can be burned out, and is about 300 to 500 ° C. When the polymer beads 22 are polystyrene beads, for example, they are heated and fired at 450 ° C. Thereby, since the polymer beads 22 are burned out, only the aluminum oxide fine particles 12 remain on the substrate 11, and a porous layer made of the aluminum oxide fine particles 12 is formed.

  In the supporting step S4, the dye 13, methyl viologen 14, and formate dehydrogenase 15 are supported on the porous layer on the surface of the substrate 11 (FIG. 6D). As a method for supporting the dye 13, methyl viologen 14 and formate dehydrogenase 15 on the porous layer on the surface of the substrate 11, for example, a solution containing the dye 13, methyl viologen 14 and formate dehydrogenase 15 is added to the surface. The substrate 11 having a porous layer is immersed in the porous layer, whereby the dye 13, methyl viologen 14, and formate dehydrogenase 15 are supported in the porous layer.

  As described above, the porous layer of the aluminum oxide fine particles 12 can be formed by heat-treating the mixed solution of the aluminum oxide fine particles 12 and the polymer beads, so that the electron transfer to the methyl viologen 14 is efficiently achieved. The formic acid generation device 10 can be created that can convert the hydrogen source into formic acid and store it.

  The formic acid generating device 10 is preferably not dried when used. This is to prevent the carried enzyme 15 from being inactivated by drying. Therefore, it is preferable to store and use in a reaction medium. As the reaction medium, an aqueous medium is suitable, and examples thereof include a mixed medium of water or an organic solvent that can be mixed with water. Examples of the organic solvent include lower alcohols such as methanol, ethanol, propanol, butanol, glycerin, and ethylene glycol, dimethylformamide, acetonitrile, dimethylacetamide, and dimethyl sulfoxide. As an aqueous medium, buffering ability may be imparted by potassium phosphate or the like.

  As a specific example of producing the formic acid generating device 10, an ethanol slurry in which aluminum oxide fine particles and polystyrene beads are mixed at a mass ratio of 10: 1 is applied onto a substrate made of non-fluorescent glass (application step S1). ) And evaporate ethanol as a solvent (drying step S2), and then heat-fire the dried substrate at about 450 ° C. to burn away polystyrene beads and form a porous layer of aluminum oxide fine particles on the substrate. The substrate having the porous layer formed on the surface is immersed in a methanol solution of 0.3 mM methyl viologen and a methanol solution of 0.3 mM N197 dye, and finally formate dehydrogenase is supported. (Supporting step S4) A formic acid generating device having a device size of 2.5 × 3 cm and a reaction volume of 2 ml was used.

When this formic acid generating device was irradiated with light using a solar simulator in a solution containing carbon dioxide (CO ₂ ), 60 mmol of formic acid was generated after 2 hours.

  Next, the formic acid decomposition apparatus 60 in the hydrogen supply system 100 will be described.

  In the formic acid decomposition apparatus 60 in the hydrogen supply system 100, formic acid supplied from the formic acid storage tank 55 is decomposed into hydrogen and carbon dioxide by a catalytic reaction in a deoxygenated environment at normal temperature and normal pressure.

  Specifically, formic acid is decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and pressure using a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone.

  Platinum acts as a catalyst to decompose formic acid into hydrogen and carbon dioxide. It is preferable to use fine particles of platinum in order to widen the reaction area, and platinum fine particles having a particle diameter of 1 nm to 50 nm.

  Thus, the catalyst function can be enhanced by using platinum fine particles having a small particle diameter.

  Moreover, the addition amount of the water-soluble polymer polyvinylpyrrolidone is 1% by mass or more and 20% by mass or less with respect to the platinum fine particles, whereby the platinum fine particles can be appropriately dispersed.

  That is, the water-soluble polymer polyvinyl pyrrolidone (PVP) is for dispersing platinum fine particles. Since the platinum fine particles easily aggregate and precipitate alone, the water-soluble polymer polyvinyl pyrrolidone can be used to maintain the function as a catalyst in a state where the platinum fine particles are dispersed. The addition amount of the water-soluble polymer polyvinylpyrrolidone (PVP) is preferably 1% by mass or more and 20% by mass or less with respect to the platinum fine particles. When the amount of the water-soluble polymer polyvinyl pyrrolidone (PVP) added is less than 1% by mass, an effect sufficient to improve the dispersibility of the platinum fine particles cannot be obtained. Moreover, when the addition amount of water-soluble polymer polyvinylpyrrolidone (PVP) exceeds 20 mass%, the catalyst function of platinum fine particles cannot be obtained sufficiently.

  In the formic acid decomposition apparatus 60 in the hydrogen supply system 100, the catalytic function of the platinum fine particles is effectively exhibited by using a combination of the platinum fine particles and the water-soluble polymer polyvinyl pyrrolidone. For example, there are polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA) as the dispersant. However, when these dispersants are used, a side reaction occurs in which water and carbon dioxide are generated from formic acid. End up. The present inventors have found that by applying a specific combination of platinum fine particles and a water-soluble polymer polyvinylpyrrolidone, a reaction in which hydrogen and a dioxide reaction occur from formic acid is selectively and efficiently generated.

  That is, in the formic acid decomposition reaction, hydrogen and carbon dioxide are generated from formic acid represented by the following reaction formula (3), and water and carbon dioxide are generated from formic acid represented by the following reaction formula (4). There is a reaction. In this hydrogen supply system 100, by using the platinum fine particles and the water-soluble polymer polyvinylpyrrolidone in combination, the side reaction of the reaction formula (4) hardly occurs, and hydrogen is efficiently generated by the reaction of the reaction formula (3). Can be generated.

HCOOH → H ₂ + CO ₂ (3)

2HCOOH + O ₂ → 2H ₂ O + 2CO ₂ (4)

  In the formic acid decomposition reaction, it is considered that the reaction of hydrogen generation occurs efficiently by combining the platinum catalyst and the water-soluble polymer polyvinylpyrrolidone so that the carbonyl group of polyvinylpyrrolidone changes the electronic state of the platinum fine particles.

  In the formic acid decomposition apparatus 60 in the hydrogen supply system 100, the decomposition reaction of formic acid is performed under deoxygenation at normal temperature and normal pressure. Since it is a catalytic reaction using platinum fine particles, heating and pressurizing are not particularly required. In addition, when oxygen is present, a side reaction in which water and carbon dioxide are generated occurs as shown in the above reaction formula (4), so that the reaction system needs to be in a deoxygenated state.

  The formic acid decomposition apparatus 60 in the hydrogen supply system 100 may separate carbon dioxide generated by the decomposition of formic acid and use it for synthesis of formic acid. For example, carbon dioxide generated in the reaction formula (3) is separated by a chemical absorption method, a membrane separation method, an adsorption method, or the like. Thereby, since the purity of hydrogen can be raised, hydrogen can be utilized more efficiently. The separated carbon dioxide can be reused without being discharged to the outside, for example, by using it in a reaction for converting to formic acid again as shown in the following reaction formula (5).

2H ₂ O + 2CO ₂ → 2HCOOH + O ₂ (5)

  As described above, in the formic acid decomposition apparatus 60 in the hydrogen supply system 100, water and carbon dioxide are removed under normal temperature and normal pressure deoxygenation by a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone. It is possible to efficiently generate hydrogen from formic acid and store it in the formic acid storage tank 55 without causing a side reaction.

  The formic acid decomposition apparatus 60 in the hydrogen supply system 100 includes, for example, at least a storage unit 61, a reaction unit 62, a separation unit 63, and a control unit 64 as shown in FIG. Hereinafter, each structure of the formic acid decomposition apparatus 60 is demonstrated.

  The storage unit 61 is for storing formic acid for generating hydrogen. The formic acid to be stored may be either sold as a product or produced by another reaction mechanism. Although the material of the storage part 61 is not specifically limited, the thing which is not corroded by formic acid is preferable.

  In the hydrogen supply system 100, the formic acid generated by the formic acid generation device 50 and stored in the formic acid storage tank 55 is supplied to the storage unit 61 of the formic acid decomposition device 60 through the flow path 40 and stored. The formic acid storage tank 55 having a cut ridge structure that can be detachably attached to the formic acid decomposition apparatus 60 may be used as the storage unit 61.

  The reaction unit 62 decomposes formic acid into hydrogen and carbon dioxide by a catalytic reaction. The reaction part 62 has a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone. For example, the catalyst may be supported on a substrate or the like, or may be held in the reaction unit 62 as a dispersion solution. In the reaction unit 62, the formic acid stored in the storage unit 61 is supplied as appropriate, and in the reaction unit 62, it is decomposed into hydrogen and carbon dioxide by a catalyst in which platinum fine particles are dispersed with the water-soluble polymer polyvinylpyrrolidone. The reaction unit 62 may include a device for appropriately stirring the solution during the formic acid decomposition reaction.

  The separation unit 63 removes carbon dioxide from the generated mixed gas of hydrogen and carbon dioxide, and raises the purity of hydrogen. For example, the separation unit 63 has a separation membrane to selectively remove carbon dioxide. The removed carbon dioxide can be used for the production of formic acid, for example, as in the above reaction formula (5), and the carbon dioxide is circulated back to the formic acid production means 50 through the flow path 70, Reuse carbon dioxide without discharging it to the outside.

  The control unit 64 mainly controls the reaction unit 62 to be deoxygenated at normal temperature and normal pressure. In particular, it is important to control the inside of the reaction unit 62 to be in a deoxygenated state so that a side reaction in which water and oxygen dioxide are generated as in the above reaction formula (4) does not occur. As a means for setting the deoxygenated state, for example, the inside of the reaction unit 62 may be replaced with nitrogen gas or the like. In addition, the control unit 64 has a mechanism that stops the formic acid decomposition apparatus 60 or eliminates the abnormal state when, for example, the reaction unit 62 or other engine detects a high temperature / pressure state or abnormality. It is preferable to provide.

  In the formic acid decomposition apparatus 60 in the hydrogen supply system 100, a side reaction in which water and carbon dioxide are generated occurs under deoxygenation at normal temperature and normal pressure by a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone. And hydrogen can be efficiently produced from formic acid.

  In the hydrogen supply system 100, the formic acid decomposition device 60 generates carbon dioxide generated by decomposing formic acid produced by the formic acid production device 50 and stored in the formic acid storage tank 55 into hydrogen and carbon dioxide. It is made to circulate by returning to the said formic acid production | generation apparatus 50 via 70, and hydrogen obtained by decomposing | disassembling formic acid is supplied to the external hydrogen power generation equipment, for example.

  That is, in this hydrogen supply system 100, as shown in the process diagram of FIG. 8, a hydrogen supply method including a formic acid generation step S11 and a formic acid decomposition step S12 is performed.

  In this hydrogen supply system 100, the formic acid generation step S11 is performed in the formic acid generation apparatus 50 using formic acid from the atmosphere or exhaust carbon dioxide by artificial photosynthesis using hydrogen ions and electrons obtained by photolysis of water into oxygen. Is generated and stored in the formic acid storage tank 55. In this formic acid generation step S11, water is photolyzed into oxygen by the hydrogen ion generation means 20 to obtain hydrogen ions / electrons, and the formic acid generation means 30 uses the formic acid generation device 10 to generate atmospheric or exhaust carbon dioxide. From the above, formic acid is generated by artificial photosynthesis and stored in the formic acid storage tank 55.

  In this formic acid production step S11, the hydrogen is produced by the formic acid production device 10 in which the porous layer of the aluminum oxide fine particles 12 formed on the surface of the solid substrate described above carries the dye 13, methyl viologen 14, and formate dehydrogenase 15. ion. Formic acid is generated from electrons and atmospheric or exhaust carbon dioxide by artificial photosynthesis and stored in the formic acid storage tank 55.

  The formic acid decomposition step S12 is a step of generating hydrogen by decomposing the formic acid supplied from the formic acid storage tank 55 in the formic acid decomposition apparatus 60. In this formic acid decomposition step S12, formic acid is decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and pressure using a catalyst in which the platinum fine particles are dispersed with the water-soluble polymer polyvinylpyrrolidone.

  In the hydrogen supply system 100, in the formic acid decomposition step S12, the carbon dioxide obtained by decomposing the formic acid stored in the formic acid storage tank 55 in the formic acid generation step S11 is returned to the formic acid generation step S11. While circulating carbon dioxide, hydrogen obtained by decomposing formic acid is supplied to an external device.

  That is, the hydrogen supply method implemented in this hydrogen supply system 100 is a porous layer made of aluminum oxide fine particles 12 formed on the surface of a solid substrate using hydrogen ions and electrons obtained by photolysis of water into oxygen. Formic acid generating step of generating and storing formic acid by artificial photosynthesis from hydrogen ion, electron and air or exhausted carbon dioxide by means of formic acid generating device 10 having dye 13, methyl viologen 14 and formate dehydrogenase 15 supported thereon S11 and a formic acid decomposition step S12 in which formic acid is decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and pressure by a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone, In the formic acid decomposition step S12, the formic acid stored in the formic acid storage tank 55 in the formic acid generation step S11 is decomposed. By returning the resulting carbon dioxide to the formic acid generation step S11, with circulating carbon dioxide, supplying hydrogen obtained by decomposing the formic acid to an external device.

  In the hydrogen supply system 100 as described above, a porous layer made of aluminum oxide fine particles 12 formed on the surface of a solid substrate using hydrogen ions / electrons obtained by photolysis of water into oxygen in the formic acid generation step S11. A formic acid generating device 10 comprising a dye 13, a methyl viologen 14, and a formate dehydrogenase 15 supported on the hydrogen ion. Formic acid is generated from electrons and atmospheric or exhaust carbon dioxide by artificial photosynthesis and stored in the formic acid storage tank 55, and a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone is used. Under the formic acid decomposition step S12 in which formic acid is decomposed into hydrogen and carbon dioxide, carbon dioxide obtained by decomposing the formic acid stored in the formic acid generation step S11 is circulated by returning it to the formic acid generation step S11. By supplying hydrogen obtained by decomposing formic acid to an external device, solar energy can be used effectively and hydrogen can be supplied safely and efficiently as an energy source.

  Next, a specific implementation example of the hydrogen supply system 100 will be described.

  The hydrogen supply system 100 configured as described above is applied to an energy supply system 1000 configured as shown in FIG. 9, for example.

  This energy supply system 1000 is an energy supply system using hydrogen as an energy source in a general house 110, such as a fuel cell that generates power using hydrogen as a fuel or a hydrogen generator driven by a hydrogen engine that uses hydrogen as fuel. A residential hydrogen power generation facility 120 is provided, and power is supplied from the residential hydrogen power generation facility 120, and hot water is supplied from the hot water storage tank 130 using the residual heat of the residential hydrogen power generation facility 120.

  This energy supply system 1000 is a daytime energy supply system using sunlight, by converting solar energy into electric energy by a solar cell panel 140 provided on the roof of the house 110, and electrolyzing water. A daytime hydrogen supply system 150 for generating hydrogen is provided. In the daytime, hydrogen is supplied from the daytime hydrogen supply system 150 to the residential hydrogen power generation facility 120.

  The energy supply system 1000 is a formic acid generator 50 that generates formic acid by artificial photosynthesis provided on the roof of the house 110 as a nighttime energy supply system that supplies hydrogen as an energy source at night in the general house 110; Hydrogen supply according to the present invention comprising a formic acid storage tank 55 for storing formic acid produced by the formic acid production device 50 and a formic acid decomposition device 60 for decomposing formic acid supplied from the formic acid storage tank 55 into hydrogen and carbon dioxide A system 100 is provided.

  In the energy supply system 1000, the hydrogen supply system 100 uses hydrogen ions and electrons obtained by photolysis of water into oxygen during the day when sunlight can be used by the formic acid generation device 50. The formic acid generating device 10 in which the porous layer of the aluminum oxide fine particles 12 formed on the surface of the solid substrate described above carries the dye 13, methyl viologen 14, and formate dehydrogenase 15 supports the hydrogen ions, electrons and the atmosphere or Formic acid is generated from exhausted carbon dioxide by artificial photosynthesis and stored in the formic acid storage tank 55. At night when sunlight is not available, the formic acid stored in the formic acid generator 50 is dissolved in platinum fine particles by the formic acid decomposition device 60. In a deoxygenated environment at normal temperature and pressure, using a catalyst dispersed with polymer polyvinylpyrrolidone Hydrogen obtained by solution, supplied to the residential hydrogen power plant 120.

  In the energy supply system 1000 having such a configuration, hydrogen can be supplied from the daytime hydrogen supply system 150 to the residential hydrogen power generation facility 120 during the day when sunlight can be used. In the formic acid generating device 50 of the supply system 100, the hydrogen ions / electrons obtained by photolysis of water into oxygen are used to form the dye 13 · on the porous layer of the aluminum oxide fine particles 12 formed on the surface of the solid substrate. By using the formic acid generating device 10 carrying the methyl viologen 14 and formate dehydrogenase 15, the hydrogen ions. Formic acid can be generated by electron photosynthesis from electrons and atmospheric or exhaust carbon dioxide and stored in the formic acid storage tank 55.

  And at night when sunlight cannot be used, the formic acid decomposition apparatus 60 converts the formic acid generated during the day when sunlight can be used by the formic acid generation apparatus 50 and stored in the formic acid storage tank 55 into platinum fine particles. Hydrogen obtained by decomposing in a deoxygenated environment at normal temperature and pressure can be supplied to the residential hydrogen power generation facility 120 by a catalyst dispersed with the polymer polyvinylpyrrolidone.

  That is, since the hydrogen supply system 100 in the energy supply system 1000 includes the formic acid generation device 50 and the formic acid decomposition device 60 configured as described above, during the day when sunlight can be used by the formic acid generation device 50, Utilizing hydrogen ions and electrons obtained by photolysis of water into oxygen, formic acid is generated from the atmospheric or exhausted carbon dioxide by artificial photosynthesis using the formic acid generation device 10 and stored in the formic acid storage tank 55 for solar light. In the formic acid decomposition apparatus 60 at night, when the formic acid stored in the formic acid storage tank 55 by the formic acid generation apparatus 50 is decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and normal pressure. Carbon dioxide is obtained as a raw material for producing formic acid by the formic acid producing device 10 and returned to the formic acid producing apparatus 50 for circulation. It causes, it is possible to supply hydrogen obtained by decomposing the formic acid safely and efficiently the residential hydrogen generation facility 120 as the energy source.

  Moreover, in the hydrogen supply system 100, the formic acid generating device 10 in which the pigment 13, the methyl viologen 14 and the formate dehydrogenase 15 are supported on the porous layer of the aluminum oxide fine particles 12 formed on the surface of the solid substrate is used to generate sunlight. By effectively using energy, the hydrogen ions. The formic acid is efficiently generated from electrons and the atmosphere or exhaust carbon dioxide by artificial photosynthesis and stored in the formic acid storage tank 55. At night when sunlight cannot be used, the formic acid decomposition apparatus 60 converts the platinum fine particles into the water-soluble polymer polyvinyl. With the catalyst dispersed by pyrrolidone, formic acid stored in the formic acid storage tank 55 can be efficiently decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and normal pressure.

Therefore, in the energy supply system 1000, the hydrogen supply system 100
By using solar energy effectively, formic acid is generated and stored, and at night when sunlight cannot be used, hydrogen obtained by decomposing formic acid is used as an energy source safely and efficiently. Can be supplied to.

  DESCRIPTION OF SYMBOLS 10 Formic acid production device, 11 Substrate, 12 Aluminum oxide fine particle, 13 Dye, 14 Methyl viologen, 15 Formic acid dehydrogenase, 20 Hydrogen ion generation means, 22 Polymer beads, 30 Formic acid production means, 40 channel, 50 Formic acid production apparatus 55, formic acid storage tank, 60, 70 formic acid decomposition apparatus, 61 storage section, 62 reaction section, 63 separation section, 64 control section, 100 hydrogen supply system, 110 general housing, 120 residential hydrogen power generation facility, 130 hot water storage tank, 140 Solar panel, 151 Toplight, 152 Bioreactor, 1000 Energy supply system

Claims (11)

A formic acid generator for generating formic acid from water and atmospheric or exhaust carbon dioxide by artificial photosynthesis;
A formic acid storage tank for storing formic acid generated by the formic acid generator;
Formic acid supplied from the formic acid storage tank comprises a formic acid decomposition device that decomposes hydrogen and carbon dioxide by catalytic reaction in a deoxygenated environment at normal temperature and pressure.
The said formic acid decomposition | disassembly apparatus supplies the hydrogen obtained by decomposing | disassembling the formic acid supplied from the said formic acid production | generation apparatus to an external apparatus, The hydrogen supply system characterized by the above-mentioned. The formic acid generating apparatus decomposes water to generate oxygen, and hydrogen ion generating means for obtaining hydrogen ions and electrons,
Formic acid generating means for generating formic acid by artificial photosynthesis from carbon dioxide and / or exhausted carbon dioxide in the atmosphere using a formic acid generating device using hydrogen ions and electrons obtained by decomposing water by the hydrogen ion generating means; The hydrogen supply system according to claim 1, further comprising:   3. The hydrogen supply system according to claim 2, wherein the formic acid generating device comprises a porous layer made of aluminum oxide fine particles formed on the surface of a substrate and supporting a dye, methyl viologen, and formate dehydrogenase.   The hydrogen supply system according to claim 3, wherein the porous layer has a thickness of 1 to 10 μm.   The formic acid decomposition apparatus is characterized in that formic acid is decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and pressure using a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone. 5. The hydrogen supply system according to any one of 1 to 4.   The hydrogen supply system according to claim 5, wherein the platinum fine particles have a particle diameter of 1 nm or more and 50 nm or less.   The hydrogen supply system according to claim 5 or 6, wherein the water-soluble polymer polyvinylpyrrolidone is added in an amount of 1% by mass to 20% by mass with respect to the platinum fine particles.   The formic acid decomposition apparatus includes at least a storage unit that stores formic acid, a reaction unit that decomposes formic acid supplied from the storage unit into hydrogen and carbon dioxide, and a separation unit that separates hydrogen and carbon dioxide generated in the reaction unit. And a control unit that controls the reaction unit under deoxygenation at normal temperature and normal pressure, wherein the reaction unit has a catalyst in which the platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone. The hydrogen supply system according to any one of claims 5 to 7.   The formic acid decomposition apparatus circulates carbon dioxide by supplying carbon dioxide obtained by decomposing formic acid supplied from the formic acid storage tank to the formic acid generation apparatus, and decomposes formic acid to generate hydrogen from an external device. The hydrogen supply system according to any one of claims 1 to 8, wherein the hydrogen supply system is supplied to the system.   The hydrogen supply system according to claim 1, wherein the external device is a residential hydrogen power generation device. Production of formic acid using dyes, methylviologen, and formate dehydrogenase supported on a porous layer of aluminum oxide fine particles formed on the surface of a solid substrate using hydrogen ions and electrons obtained by photolysis of water into oxygen Formic acid production step of producing and storing formic acid by artificial photosynthesis from the hydrogen ions, electrons and atmospheric or exhaust carbon dioxide by the device,
A formic acid decomposition step for decomposing formic acid into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and pressure by a catalyst in which platinum fine particles are dispersed with a water-soluble polymer polyvinylpyrrolidone.
In the formic acid decomposition step, carbon dioxide obtained by decomposing the formic acid stored in the formic acid generation step is circulated by supplying the formic acid generation step, and formic acid is decomposed to supply hydrogen to an external device. A method for supplying hydrogen.

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