JP2022178265A - Hydrogen supply system and hydrogen supply method - Google Patents

Abstract

To provide a hydrogen supply system and a hydrogen supply method, capable of safely and efficiently supplying hydrogen as an energy source by effectively utilizing solar energy.SOLUTION: A hydrogen supply system 100 comprises: a formic acid production device 50 that produces formic acid from water and carbon dioxide present in the atmosphere or in exhaust by way of artificial photosynthesis; a formic acid storage tank 55 that stores formic acid produced by the formic acid production device 50; a formic acid decomposition device 60 that decomposes formic acid supplied from the formic acid storage tank 55 into hydrogen and carbon dioxide by a catalytic reaction at a normal temperature and a normal pressure under an environment free of oxygen; and a power generator 120 that has a hydrogen engine 121 driven by hydrogen supplied from the formic acid decomposition device 60 as a fuel and a power generating unit 121a using the hydrogen engine 121 as a power source, wherein carbon dioxide supplied, without separating from hydrogen, from the formic acid decomposition device 60 is circulated to the formic acid production device 50 via the power generator 120, and carbon dioxide produced by the power generator 120 is circulated to the formic acid production device 50.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a hydrogen supply system and a hydrogen supply method, and more particularly to a hydrogen supply system and a hydrogen supply method utilizing solar energy.

Fossil fuels such as coal and petroleum have been widely used as energy sources, but in recent years, there are problems such as resource depletion and global warming caused by carbon dioxide. ing. Moreover, utilization of solar energy is mentioned as a representative of clean energy.

In recent years, hydrogen has been extracted by electrolyzing water using electricity generated by photovoltaic power generation, etc., and the development of fuel cells and hydrogen engines that use this hydrogen as a fuel resource, as well as hydrogen fuel cell vehicles and hydrogen engine vehicles equipped with these technology development is underway.

The applicant of the present application has a formic acid generator that produces and stores formic acid through artificial photosynthesis from the atmosphere or exhaust carbon dioxide using a formic acid generator, and decomposes formic acid into hydrogen and carbon dioxide through a catalytic reaction in a deoxygenated environment at normal temperature and normal pressure. The decomposing device supplies carbon dioxide obtained by decomposing formic acid supplied from the formic acid generating device to the formic acid generating device to circulate carbon dioxide, and supplies hydrogen obtained by decomposing formic acid to an external device. A hydrogen supply system that does this has previously been proposed (see, for example, Patent Document 1). In this hydrogen supply system, the carbon dioxide obtained by decomposing the formic acid supplied from the formic acid generator is supplied to the formic acid generator and circulated. Hydrogen obtained by decomposing formic acid by the device can be safely and efficiently supplied to an external device as an energy source.

JP 2018-118877 A

By the way, in the hydrogen supply system described in Patent Document 1, the carbon dioxide obtained by decomposing the formic acid supplied from the formic acid generator is recycled back to the formic acid generator, thereby discharging the carbon dioxide to the outside. It was reused without any waste. However, in order to return the carbon dioxide to the formic acid generator, it is necessary to separately provide a separation device for separating hydrogen and carbon dioxide. As a result, problems have occurred in the hydrogen supply system, such as the need to install the separation device and the need for an installation space for installing the separation device.

Therefore, the present invention is a hydrogen supply that can safely and efficiently supply hydrogen as an energy source by effectively using solar energy even when a separation device for separating hydrogen and carbon dioxide is not provided. An object of the present invention is to provide a system and a hydrogen supply method.

The present invention is a hydrogen supply system comprising: a formic acid generator for generating formic acid by artificial photosynthesis from water and the atmosphere or exhaust carbon dioxide; a formic acid storage tank for storing the formic acid generated by the formic acid generator; It is driven by a formic acid decomposition device that decomposes formic acid supplied from a formic acid storage tank into hydrogen and carbon dioxide through a catalytic reaction in a deoxygenated environment at normal temperature and pressure, and hydrogen supplied from the formic acid decomposition device as fuel. A generator having a hydrogen engine and a power generation unit driven by the hydrogen engine, wherein carbon dioxide supplied without being separated from hydrogen from the formic acid decomposing device is supplied through the generator to generate the formic acid. It is characterized by circulating through the device.

In the hydrogen supply system according to the present invention, the formic acid generator includes: hydrogen ion generating means for decomposing water to generate oxygen and obtaining hydrogen ions and electrons; a formic acid generating means for generating formic acid by artificial photosynthesis from carbon dioxide in the atmosphere and/or exhaust carbon dioxide by means of a formic acid generating device using the hydrogen ions and electrons obtained.

In the hydrogen supply system according to the present invention, the formic acid generation device may have a substrate surface coated with a mixture of titanium oxide fine particles, a dye, and a viologen compound.

In the hydrogen supply system according to the present invention, the formic acid decomposition device converts formic acid into hydrogen and carbon dioxide under a deoxidized environment at normal temperature and normal pressure using a catalyst in which platinum fine particles are dispersed in a water-soluble polymer polyvinylpyrrolidone. It can be disassembled.

In the hydrogen supply system according to the present invention, the formic acid decomposition device includes a storage unit for storing at least formic acid, a reaction unit for decomposing the formic acid supplied from the storage unit into hydrogen and carbon dioxide, and the reaction unit at room temperature. and a control section for controlling under normal pressure deoxygenation, and the reaction section may have a catalyst in which the platinum fine particles are dispersed in a water-soluble polymer polyvinylpyrrolidone.

In the hydrogen supply system according to the present invention, the generator further includes a heat recovery unit that recovers heat generated by the hydrogen engine, and an inverter that converts the electric power generated by the power generation unit from direct current to alternating current. can be

The present invention relates to a method for supplying hydrogen, wherein a mixture of titanium oxide fine particles, a pigment, and a viologen compound is coated on the surface of a solid substrate using hydrogen ions and electrons obtained by photolyzing water into oxygen. A formic acid generation step in which formic acid is generated and stored by artificial photosynthesis from hydrogen ions, electrons and the atmosphere or exhaust carbon dioxide using a generation device, and a catalyst formed by dispersing platinum fine particles in a water-soluble polymer polyvinylpyrrolidone.・A power generating unit driven by a formic acid decomposition process in which formic acid is decomposed into hydrogen and carbon dioxide under normal pressure and deoxygenated environment, and a hydrogen engine powered by the hydrogen obtained by decomposition in the formic acid decomposition process. and a power generation step for generating electric power by supplying carbon dioxide obtained by decomposition in the formic acid decomposition step and obtained through the power generation step to the formic acid generation step without separating it from hydrogen. , characterized by circulating carbon dioxide.

As described above, according to the present invention, it is possible to provide a hydrogen supply system and a hydrogen supply method that effectively utilize solar energy and safely and efficiently supply hydrogen as an energy source. A practical residential energy supply system can be realized.

It is a block diagram showing an example of composition of a hydrogen supply system which carries out the present invention. FIG. 3 is a schematic diagram showing a configuration example of a formic acid generator in the hydrogen supply system; FIG. 3 is a schematic diagram showing a configuration example of a formic acid generating device provided in the formic acid generating apparatus; FIG. 4 is a schematic diagram showing reactions in the formic acid generation device; FIG. 2 is a flowchart showing an outline of a method for producing the formic acid generation device; It is a schematic diagram showing the structural example of the formic acid decomposition apparatus in the said hydrogen supply system. It is process drawing which shows the execution process of the hydrogen supply method performed by the said hydrogen supply system. BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows an example of the residential energy supply system to which this invention is applied. It is a block diagram which shows the structural example of a generator. It is a flowchart which shows the outline of the process in a generator.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It goes without saying that the present invention is not limited to the following examples, and can be arbitrarily modified 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 generator 50 by artificial photosynthesis, a formic acid storage tank 55 for storing the formic acid generated by the formic acid generator 50, and hydrogen and carbon dioxide from the formic acid supplied from the formic acid storage tank 55. and a generator 120 that generates electricity from hydrogen supplied from the formic acid decomposition device 60 and oxygen in the atmosphere.

The formic acid generator 50 generates formic acid by artificial photosynthesis from water and carbon dioxide supplied from the atmosphere or from the generator 120 and circulating in the hydrogen supply system 100 , and stores the formic acid in the storage tank 55 .

The formic acid decomposing device 60 decomposes formic acid into hydrogen and carbon dioxide through a catalytic reaction in a deoxygenated environment at normal temperature and normal pressure. Hydrogen and carbon dioxide obtained by decomposition are supplied to the generator 120 .

In the hydrogen supply system 100, the formic acid storage tank 55 has a stationary structure in which it is simultaneously connected to the formic acid generator 50 and the formic acid decomposition device 60 via the flow path 40. It is not necessary to connect to the decomposing device 60 at the same time, and a cartridge type structure can be adopted that is detachably connected to the formic acid generating device 50 and the formic acid decomposing device 60 separately.

For example, the formic acid generator 50 in the hydrogen supply system 100 includes, as shown in FIG. and a formic acid generating means 30 using the formic acid generating device 10 for generating formic acid by.

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

The formic acid generating means 30 utilizes hydrogen ions and electrons obtained by decomposing water by the hydrogen ion generating means 20, and the formic acid generating device 10 performs artificial photosynthesis from atmospheric carbon dioxide and/or exhaust carbon dioxide. produces formic acid.

The formic acid generating device 10 used in the formic acid generating means 30 is composed of, for example, a substrate 11, titanium oxide fine particles 12, a dye 13, a methylviologen 14, and a formic acid dehydrogenase 15, as shown in FIG. .

First, each configuration of the formic acid generation device 10 will be described.

A substrate 11 has a surface coated with a mixture of titanium oxide fine particles 12 , dye 13 and methyl viologen 14 . The material of the substrate 11 is not particularly limited, but may be, for example, a metal substrate such as aluminum, a glass substrate such as non-fluorescent glass, or a resin sheet such as a PET sheet.

The titanium oxide fine particles 12 play a role of donating electrons to the dye 13 and the methylviologen 14 by light (mainly ultraviolet rays) in the formic acid generation reaction.

The dye 13 is a photosensitizer that plays a role of assisting the reaction and luminescence process by transferring the light energy obtained by itself to other substances. That is, the dye 13 has a function (photoelectric conversion ability) that absorbs light energy in a reaction system irradiated with light, converts the energy into electron energy, and transfers electrons to an electron transporter (coenzyme). is. Examples of dye 13 include porphyrin derivatives, ruthenium bipyridine complex derivatives, and pyrene derivatives. ), ruthenium tris-bipyridine, chlorophyll and the like can be used.

Methylviologen (MV) 14 is an artificial coenzyme having an electron transport function of receiving electrons from pigment 13 and transferring electrons to other substances. In other words, the methyl viologen 14 has a reducing function of receiving electrons from the pigment 13 photoexcited by light irradiation and transferring the electrons to the enzyme.

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

The formic acid generating device 10 may contain an electron donor. An electron donor has a function of transferring electrons to another substance and a reducing function, and itself is oxidized. That is, the electron donor has a function of transferring electrons to the dye 13 that has lost electrons and a reducing function in the reaction system irradiated with light. Examples of electron donors include triethanolamine, ethylenediamine, ethylenediaminetetraacetate, ethylenediamine hydrochloride, triethylamine, and mercaptoethanol.

According to the formic acid generator 50 having such a configuration, in the formic acid generator 10, hydrogen ions and electrons generated by water decomposition and carbon dioxide discharged from the air and/or other organs can be effectively used. Also, the titanium oxide fine particles 12 can efficiently achieve electron transfer to the methyl viologen 14 , and the hydrogen source can be converted into formic acid and stored in the formic acid storage tank 55 .

That is, the formic acid generator 50 in this hydrogen supply system 100 includes hydrogen ion generating means 20 that decomposes water to generate oxygen, acquire hydrogen ions and electrons, titanium oxide fine particles 12, pigment 13, methyl viologen 14, and formic acid dehydration. a formic acid generating means 30 for generating formic acid by artificial photosynthesis from hydrogen ions, electrons and carbon dioxide by means of a formic acid generating device 10 coated on a substrate 11 with premixed enzymes 15; Using the hydrogen ions and electrons obtained by photolyzing water into oxygen, the formic acid generating means 30 generates formic acid by artificial photosynthesis from the atmosphere or the exhaust carbon dioxide by the formic acid generating device 10, and stores formic acid. Store in tank 55 .

In this hydrogen supply system 100, the formic acid generator 50 is used as a photochemical reaction device. During use, it is particularly preferable to have a structure in which the formic acid generating device 10 of the formic acid generating means 30 is irradiated with light. The sun, an artificial light source, or the like can be used as the light source for irradiating the formic acid generation device 10 with light.

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

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

The hydrogen ion generating means 20 is not particularly limited as long as it is a means for causing the above reaction. For example, a water decomposition device such as a substrate supporting a photocatalyst is used.

Here, FIG. 4 shows a schematic diagram showing the reaction in the formic acid generation device 10. As shown in FIG. For example, by irradiating light in the presence of an electron donor, a dye is excited, electrons (e ⁻ ) are transferred from the excited dye to methylviologen (MV ²⁺ ), and methylviologen that has received the electrons It is reduced to produce reduced methylviologen (MV ⁺ ). Reduced methylviologen (MV ⁺ ) supplies electrons to formate dehydrogenase (FDH). This causes an enzymatic reaction to proceed, and formic acid is produced from hydrogen ions, electrons, and carbon dioxide.

In the formic acid producing means 30, the formic acid producing device 10 produces formic acid from hydrogen ions, electrons, and carbon dioxide through the photoreaction (artificial photosynthesis) process shown in FIG. 4 (formula (2) below). At this time, the hydrogen ions and electrons generated by the hydrogen ion generator 20 are consumed. Carbon dioxide can also be used as it is present in the atmosphere and/or in exhaust gases from other engines.
CO ₂ +2H ⁺ +2e ⁻ →HCOOH (2)

In the hydrogen supply system 100, the formic acid produced by the formic acid producing device 50 and stored in the formic acid storage tank 55 is decomposed through the flow path 40, for example, at night when sunlight cannot be obtained and artificial photosynthesis cannot be performed. It is sent to the device 60 and decomposed by the formic acid decomposing device 60 to generate and utilize hydrogen, which is consumed, generated electricity, or the like by an engine.

The formic acid generation device 10 is preferably not dried before use. This is to prevent the carried enzyme 15 from being deactivated by drying. Therefore, it is preferably stored and used in a reaction medium, and the reaction medium is preferably an aqueous medium, including water or a mixed medium with an organic solvent miscible with water. Organic solvents include lower alcohols such as methanol, ethanol, propanol, butanol, glycerin and ethylene glycol, dimethylformamide, acetonitrile, dimethylacetamide and dimethylsulfoxide. Buffering capacity may be imparted to the aqueous medium by potassium phosphate or the like.

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

In the formic acid decomposition device 60 in the hydrogen supply system 100, the 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 fine particles of platinum are dispersed in polyvinylpyrrolidone, a water-soluble polymer. When decomposing formic acid into hydrogen and carbon dioxide, it is desirable to mix a cationic polymer.

As an example of the cationic polymer, poly(diallyldimethylammonium chloride) (PDADMA) represented by the following general formula (I) can be used. PDADMA has a chemical structure similar to that of PVP, and can achieve hydrogen generation efficiency five times or more as compared to the case where the cationic polymer is not mixed.

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

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

Further, 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, so that the platinum fine particles can be appropriately dispersed.

That is, the water-soluble polymer polyvinylpyrrolidone (PVP) is for dispersing the platinum fine particles. Since platinum fine particles are likely to aggregate and precipitate when used alone, the use of water-soluble polymer polyvinylpyrrolidone makes it possible to retain the function of a catalyst while the platinum fine particles are dispersed. The amount of the water-soluble polymer polyvinylpyrrolidone (PVP) added is preferably 1% by mass or more and 20% by mass or less with respect to the platinum fine particles. If the amount of the water-soluble polymer polyvinylpyrrolidone (PVP) added is less than 1% by mass, a sufficient effect of improving the dispersibility of the platinum fine particles cannot be obtained. Further, when the amount of the water-soluble polymer polyvinylpyrrolidone (PVP) added exceeds 20% by mass, the catalytic function of the platinum fine particles cannot be sufficiently obtained.

In the formic acid decomposition device 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 polyvinylpyrrolidone. For example, dispersants include polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA), but when these dispersants are used, a side reaction occurs in which water and carbon dioxide are produced from formic acid. put away. The present inventors have found that by applying a specific combination of platinum fine particles and water-soluble polymer polyvinylpyrrolidone, a reaction in which formic acid generates hydrogen and dioxide is selectively and efficiently generated.

That is, the decomposition reaction of formic acid includes a reaction in which hydrogen and carbon dioxide are produced from formic acid represented by the following reaction formula (3), and a reaction in which water and carbon dioxide are produced from formic acid represented by the following reaction formula (4). there is a reaction. In this hydrogen supply system 100, by using a combination of platinum fine particles and water-soluble polymer polyvinylpyrrolidone, the side reaction of reaction formula (4) hardly occurs, and hydrogen is efficiently produced by the reaction of reaction formula (3). can be generated at However, when it is desired to preferentially generate water, the reaction of reaction formula (4) should be preferentially caused.

HCOOH→H ₂ +CO ₂ (3)

2HCOOH+ _O2 →2H2O _{+ 2CO2} (4)

In the decomposition reaction of formic acid, it is thought that the combination of a platinum catalyst and a water-soluble polymer, polyvinylpyrrolidone, causes the carbonyl group of polyvinylpyrrolidone to change the electronic state of the platinum fine particles, resulting in an efficient hydrogen generation reaction.

Further, in the formic acid decomposition device 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, no particular heating or pressure is required. In addition, the presence of oxygen causes a side reaction in which water and carbon dioxide are produced as shown in the above reaction formula (4), so the reaction system must be kept in a deoxygenated state. However, when the reaction of the reaction formula (4) is desired to occur, the reaction system does not necessarily need to be in a deoxidized state.

As described above, in the formic acid decomposition device 60 in the hydrogen supply system 100, water and carbon dioxide are deoxidized at normal temperature and normal pressure by means of a catalyst composed of platinum fine particles dispersed in the water-soluble polymer polyvinylpyrrolidone. Hydrogen and carbon dioxide can be efficiently produced from formic acid and stored in the formic acid storage tank 55 without any side reactions occurring.

Next, a method for manufacturing a formic acid generation device according to one embodiment of the present invention will be described. FIG. 5 is a flow diagram outlining a method for fabricating a formic acid generating device according to one embodiment of the present invention. As shown in FIG. 5, the formic acid generating device according to one embodiment of the present invention is manufactured through a weighing step S1, a mixing step S2, and a coating step S3. Each step will be described below.

In the weighing step S1, at least the dye and the viologen compound are weighed. Then, in the mixing step S2, the pigment and viologen compound weighed in the weighing step S1 are added to the titanium oxide fine particle dispersion and mixed. As the titanium oxide fine particle dispersion liquid, for example, one in which titanium oxide fine particles are dispersed in an ethanol solution is used. In the mixing step S2, for example, a titanium oxide fine particle dispersion liquid dispersed in ethanol is added to the weighed pigment and viologen compound, and the mixture is subjected to ultrasonic treatment. The pigment and the viologen compound may be mixed in advance with an organic solvent or the like before adding the titanium oxide fine particle dispersion.

In the mixing step S2, the mixing ratio of the titanium oxide fine particles and the pigment is preferably 10000:1 to 20000:1 in mass ratio. By mixing in such a mixing ratio, the formic acid production reaction can be promoted efficiently. Also, this mixing ratio must be optimized according to the composition of the titanium oxide fine particles and the pigment used. As for the mixing ratio of the dye and the viologen compound, for example, in the case of methylviologen, the mass ratio of dye:methylviologen is preferably 1:15 to 1:25.

In the coating step S3, the mixed mixture is coated on the substrate. For example, a resin sheet such as a PET sheet may be used as the substrate.

After that, the substrate coated with the mixed solution is dried. As a result, ethanol or the like, which is a solvent in the mixed liquid, evaporates, leaving a mixture of titanium oxide fine particles, a dye, and a viologen compound on the substrate. In addition, it may be stored and used in a mixed medium of water or an organic solvent miscible with water without drying. Note that the method for producing a formic acid-generating device according to an embodiment of the present invention is not necessarily limited to the above steps. For example, the formic acid-generating device may be produced by another coating/adsorption method such as vapor deposition.

Also, the average particle size of the titanium oxide fine particles is not particularly limited, but is, for example, 20 to 50 nm. When the average particle size of the titanium oxide fine particles exceeds 50 nm, the performance for formic acid generation may be lowered.

The formic acid decomposition device 60 in the hydrogen supply system 100 includes at least a storage section 61, a reaction section 62, and a control section 63, for example, as shown in FIG. Each configuration of the formic acid decomposition apparatus 60 will be described below.

The storage unit 61 stores formic acid for generating hydrogen. The formic acid to be stored may be either commercially available product or produced by other reaction mechanisms. Although the material of the storage part 61 is not particularly limited, it is preferable to use a material that is not corroded by formic acid.

In this hydrogen supply system 100, the formic acid generated by the formic acid generator 50 and stored in the formic acid storage tank 55 is supplied through the flow path 40 to the storage section 61 of the formic acid decomposition apparatus 60 and stored therein. The formic acid storage tank 55 having a cartridge type structure that can be detachably attached to the formic acid decomposition apparatus 60 can be used as the storage section 61 .

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

The control unit 63 mainly controls the reaction unit 62 so that it is deoxidized at room temperature and pressure. In particular, it is important to control the inside of the reaction section 62 to be in a deoxygenated state so that the side reaction in which water and carbon dioxide are produced as in reaction formula (4) does not occur. As a means for deoxygenating, for example, replacing the inside of the reaction section 62 with nitrogen gas or the like can be mentioned. In addition, the control unit 63 has a mechanism for stopping the formic acid decomposing device 60 or resolving the abnormal state, for example, when a high temperature/pressurized state or an abnormality is detected in the reaction unit 62 or other engine. It is preferable to have

In the formic acid decomposition device 60 in the hydrogen supply system 100, a side reaction occurs in which water and carbon dioxide are generated under deoxygenation at normal temperature and normal pressure due to a catalyst in which platinum fine particles are dispersed in the water-soluble polymer polyvinylpyrrolidone. Hydrogen can be efficiently produced from formic acid without

In the hydrogen supply system 100, the formic acid decomposing device 60 decomposes the formic acid generated by the formic acid generating device 50 and stored in the formic acid storage tank 55 into hydrogen and carbon dioxide. It feeds the generator 120 without separation.

In this hydrogen supply system 100, as shown in the process diagram of FIG. 7, a hydrogen supply method having a formic acid generation step S11, a formic acid decomposition step S12, and a recovery/circulation step S13 is implemented.

In the hydrogen supply system 100, the formic acid generation step S11 utilizes hydrogen ions and electrons obtained by photolyzing water into oxygen in the formic acid generation device 50 to generate formic acid from the atmosphere or exhaust carbon dioxide through artificial photosynthesis. 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 and electrons. Formic acid is produced by artificial photosynthesis and stored in the formic acid storage tank 55 .

In this formic acid generation step S11, the hydrogen ion. Formic acid is produced by artificial photosynthesis from electrons and air or exhaust carbon dioxide and stored in a formic acid storage tank 55 .

The formic acid decomposition step S12 is a step in which the formic acid decomposition unit 60 decomposes the formic acid supplied from the formic acid storage tank 55 to generate hydrogen. In this formic acid decomposition step S12, formic acid is decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and normal pressure using a catalyst in which the platinum fine particles are dispersed in the water-soluble polymer polyvinylpyrrolidone. As a result, approximately equal volumes of hydrogen and carbon dioxide are produced.

The recovery/circulation step S<b>13 is a step of recovering and circulating carbon dioxide generated in the hydrogen supply system 100 . Of the hydrogen and carbon dioxide supplied without being separated from the formic acid decomposition device 60, the volume of hydrogen decreases as a result of combustion in the power generator 120, but carbon dioxide is hardly consumed in the combustion in the power generator 120. It never decreases. Therefore, the carbon dioxide generated in the formic acid decomposition step S12 is resupplied to the formic acid generator 50 via the generator 120 while the amount of carbon dioxide supplied from the formic acid decomposition device 60 is substantially maintained. That is, the carbon dioxide recovered from the generator 120 is circulated in the hydrogen supply system 100 and supplied to the formic acid generator 50 again.

Next, a specific implementation example of the hydrogen supply system 100 will be described. The hydrogen supply system 100 is applied, for example, to an energy supply system 1000 configured as shown in FIG.

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

This energy supply system 1000, as a daytime energy supply system using sunlight, converts sunlight energy into electric energy by means of a solar cell panel 140 provided on the roof of a house 110, and electrolyzes water. A daytime hydrogen supply system 150 for generating hydrogen is provided. During the daytime, hydrogen is supplied from the daytime hydrogen supply system 150 to the generator 120 .

In addition, this energy supply system 1000 is a nighttime energy supply system that supplies hydrogen as an energy source in a general house 110 at night. A formic acid storage tank 55 for storing the formic acid produced by the formic acid production device 50, a formic acid decomposition device 60 for decomposing the formic acid supplied from the formic acid storage tank 55 into hydrogen and carbon dioxide, and hydrogen from the formic acid decomposition device 60. A hydrogen supply system 100 according to the present invention having a generator 120 for supplying carbon dioxide supplied without being separated to the formic acid generator 50 .

In this energy supply system 1000, the hydrogen supply system 100 utilizes hydrogen ions and electrons obtained by photolyzing water into oxygen during the day when sunlight can be used by the formic acid generator 50, Titanium oxide fine particles 12, dye 13, methylviologen 14, and formate dehydrogenase 15 are mixed in advance and coated on a substrate 11 by a formic acid generating device 10, which produces artificial photosynthesis from the hydrogen ions, electrons, and the atmosphere or exhaust carbon dioxide. Formic acid is produced and stored in a formic acid storage tank 55, and at night when sunlight is not available, the formic acid stored by the formic acid producing device 50 is dispersed by the formic acid decomposing device 60 with the platinum fine particles in the water-soluble polymer polyvinylpyrrolidone. Hydrogen obtained by decomposing in a deoxygenated environment at normal temperature and normal pressure is supplied to the generator 120 by a catalyst composed of the following.

FIG. 9 shows a configuration example of the generator 120. As shown in FIG. The power generator 120 includes a hydrogen engine 121 that is driven using hydrogen supplied from the formic acid decomposition device 60 as fuel, a power generation section 121a that is driven by the hydrogen engine 121, and a heat recovery device that recovers heat generated by the hydrogen engine 121. 122, and an inverter 123 that converts the power generated by the power generation unit 121a from direct current to alternating current.

The hydrogen engine 121 is driven using the hydrogen supplied from the formic acid decomposition device 60 as fuel, and as the hydrogen engine 121 is driven, the hydrogen reacts with oxygen in the air and the hydrogen burns. As a result, water is produced as shown in the following formula (5).
2H ₂ +O ₂ →2H ₂ O (5)
Further, when the hydrogen engine 121 drives the power generation unit 121 a , electromotive force is generated in the power generation unit 121 a and the generated DC power is supplied to the inverter 123 . That is, electricity is generated in the power generator 120 as the power generation unit 121 a is driven by the hydrogen engine 121 .

Although carbon dioxide is also supplied to the hydrogen engine 121 from the formic acid decomposition device 60, this carbon dioxide does not affect the combustion reaction within the hydrogen engine 121 at all. Therefore, the process of providing a separation device for separating hydrogen and carbon dioxide in advance can be omitted.

The heat recovery device 122 is composed of, for example, a heat exchanger or the like, and recovers heat generated by the hydrogen engine 121 . Specifically, the heat recovery device 122 is connected to the hydrogen engine 121 so as to be able to use heat (exhaust heat) generated when the hydrogen engine 121 generates electric power. The heat recovery device 122 functions as a hot water generator and is connected to, for example, a hot water storage tank (not shown). The water (hot water) stored in the hot water storage tank is heated by the heat recovered by the heat recovery device 122 .

Inverter 123 is electrically connected to hydrogen engine 121 . The inverter 123 converts the DC power supplied from the power generation unit 121a into AC power. AC power output from inverter 123 is supplied to load 200 .

FIG. 10 is a flow diagram showing the processing performed by the generator 120 described above. As shown in FIG. 10, the generator 120 performs a combustion step S21 and a circulation step S22.

In the hydrogen supply system 100, the combustion step S21 is a step of burning the hydrogen supplied from the formic acid decomposition device 60 and the oxygen taken from the atmosphere. In this combustion step S21, electricity and water are generated by reacting hydrogen and oxygen.

The circulation step S22 is a step of supplying carbon dioxide supplied from the formic acid decomposition device 60 to the formic acid generation device 50 together with hydrogen. Specifically, the carbon dioxide supplied from the formic acid decomposition device 60 does not participate in the combustion reaction within the hydrogen engine 121 and is supplied to the formic acid generation device 50 via the generator 120 . That is, carbon dioxide taken into the hydrogen supply system 100 from the atmosphere circulates within the hydrogen supply system 100 .

In the energy supply system 1000 having such a configuration, hydrogen can be supplied from the daytime hydrogen supply system 150 to the generator 120 during the daytime when sunlight can be used, and the hydrogen supply system 100 according to the present invention can In the formic acid generator 50, the titanium oxide fine particles 12, the dye 13, the methyl viologen 14, and the formic acid dehydrogenase 15 are mixed in advance using hydrogen ions and electrons obtained by photolyzing water into oxygen, and the substrate 11, the hydrogen ions. Formic acid can be produced by artificial photosynthesis from electrons and the atmosphere or exhausted carbon dioxide and stored in the formic acid storage tank 55 .

At night when sunlight cannot be used, the formic acid generated by the formic acid generator 50 during the day when sunlight can be used and stored in the formic acid storage tank 55 in the formic acid decomposition device 60 is converted into water-soluble platinum fine particles. Hydrogen obtained by decomposition in a deoxygenated environment at normal temperature and normal pressure can be supplied to the generator 120 by the catalyst dispersed in the polymer polyvinylpyrrolidone.

That is, since the hydrogen supply system 100 in the energy supply system 1000 includes the formic acid generator 50 and the formic acid decomposition device 60 configured as described above, the formic acid generator 50 can be used during the day when sunlight can be used. Using hydrogen ions and electrons obtained by photolyzing water into oxygen, formic acid is generated by artificial photosynthesis from the atmosphere or exhaust carbon dioxide by the formic acid generation device 10, and stored in the formic acid storage tank 55, and sunlight is generated. is not available, the formic acid decomposing device 60 decomposes the formic acid stored in the formic acid storage tank 55 by the formic acid generating device 50 into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and normal pressure. Carbon dioxide as a raw material for producing formic acid is obtained by the formic acid producing device 10 and circulated back to the formic acid producing device 50, and hydrogen obtained by decomposing formic acid is safely and efficiently used as an energy source for the generator 120. can be supplied to

Furthermore, in the hydrogen supply system 100, by reusing the carbon dioxide that is taken in from the atmosphere and supplied via the generator 120, in the hydrogen supply system 100, artificial The process of producing formic acid through photosynthesis, the process of breaking down formic acid into hydrogen and carbon dioxide in the formic acid decomposition device 60, and the circulation process of carbon dioxide supplied together with hydrogen via the generator 120 can be repeatedly executed. Also, the carbon dioxide generated by the generator 120 can be circulated to the formic acid generator 50 .

That is, when formic acid decomposes, hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) are generated in equal volumes, and when this is supplied to a generator 120 such as a hydrogen engine, only hydrogen reacts with air to generate electricity. of combustion. On the other hand, carbon dioxide does not react and is discharged from the generator 120 as it is, so it has an important feature that the process of separating hydrogen and carbon dioxide in advance can be omitted.

Therefore, in the energy supply system 1000, the hydrogen supply system 100 effectively utilizes solar energy to generate and store formic acid, and at night when sunlight cannot be used, hydrogen obtained by decomposing formic acid is produced. It can be safely and efficiently supplied to the generator 120 as an energy source.

Although one embodiment and examples of the present invention have been described in detail above, those skilled in the art will understand that many modifications are possible without substantially departing from the novel matters and effects of the present invention. would be easy to understand. Therefore, all such modifications are intended to be included in the scope of the present invention.

For example, a term described at least once in the specification or drawings together with a different, broader or synonymous term can be replaced with the different term anywhere in the specification or drawings. Also, the configurations of the horizontal members and the building structure are not limited to those described in the embodiment and examples of the present invention, and various modifications are possible.

10 formic acid generating device 11 substrate 12 titanium oxide fine particles 13 dye 14 methyl viologen 15 formic acid dehydrogenase 20 hydrogen ion generating means 22 polymer beads 30 formic acid generating means 40 channel 50 formic acid generator , 55 formic acid storage tank, 60 formic acid decomposition device, 61 storage unit, 62 reaction unit, 63 control unit, 100 hydrogen supply system, 110 general house, 120 generator, 121 hydrogen engine, 121a power generation unit, 122 heat recovery device, 123 Inverter, 130 hot water storage tank, 140 solar cell panel, 1000 energy supply system

The present invention is a hydrogen supply system comprising: a formic acid generator for generating formic acid by artificial photosynthesis from water and the atmosphere or exhaust carbon dioxide; a formic acid storage tank for storing the formic acid generated by the formic acid generator; a formic acid decomposition device that decomposes formic acid supplied from a formic acid storage tank into hydrogen and carbon dioxide through a catalytic reaction in a deoxygenated environment at normal temperature and normal pressure ; Among them , a hydrogen engine that drives using hydrogen as a fuel, and a generator having a power generation unit that uses the hydrogen engine as a drive source, wherein the hydrogen and carbon dioxide supplied from the formic acid decomposition device are not discharged from the generator. It is characterized by further comprising a path for circulating carbon dioxide discharged in the reaction to the formic acid generator.

The present invention relates to a method for supplying hydrogen, wherein a mixture of titanium oxide fine particles, a pigment, and a viologen compound is coated on the surface of a solid substrate using hydrogen ions and electrons obtained by photolyzing water into oxygen. A formic acid generation step in which formic acid is generated and stored by artificial photosynthesis from hydrogen ions, electrons and the atmosphere or exhaust carbon dioxide using a generation device, and a catalyst formed by dispersing platinum fine particles in a water-soluble polymer polyvinylpyrrolidone.・A formic acid decomposition process in which formic acid is decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal pressure, and a hydrogen engine driven by hydrogen among the hydrogen and carbon dioxide obtained by decomposition in the formic acid decomposition process. and a power generation step of generating electric power by a power generation unit driven by is returned to the formic acid production step for reuse , thereby circulating carbon dioxide.

Claims (7)

a formic acid generator that generates formic acid by artificial photosynthesis from water and air or exhaust carbon dioxide;
a formic acid storage tank for storing the formic acid generated by the formic acid generator;
a formic acid decomposition device that decomposes formic acid supplied from the formic acid storage tank into hydrogen and carbon dioxide by a catalytic reaction in a deoxygenated environment at normal temperature and normal pressure;
a generator having a hydrogen engine driven by using hydrogen supplied from the formic acid decomposition apparatus as a fuel;
A hydrogen supply system, characterized in that carbon dioxide supplied without being separated from hydrogen from the formic acid decomposing device is circulated to the formic acid generating device via the generator. The formic acid generator comprises hydrogen ion generating means for decomposing water to generate oxygen and obtaining hydrogen ions and electrons;
a formic acid generating means for generating formic acid by artificial photosynthesis from atmospheric carbon dioxide and/or exhaust carbon dioxide 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, characterized by comprising: 3. The hydrogen supply system according to claim 2, wherein said formic acid generating device has a substrate coated with a mixture of fine titanium oxide particles, a dye and a viologen compound. The formic acid decomposing device decomposes formic acid into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and normal pressure with a catalyst comprising platinum fine particles dispersed in a water-soluble polymer polyvinylpyrrolidone. 4. The hydrogen supply system according to any one of 1 to 3. The formic acid decomposition apparatus comprises a storage section for storing at least formic acid, a reaction section for decomposing the formic acid supplied from the storage section into hydrogen and carbon dioxide, and the reaction section under normal temperature and normal pressure deoxygenation conditions. 5. The hydrogen supply system according to claim 4, further comprising a control section, and wherein the reaction section has a catalyst in which the platinum fine particles are dispersed in a water-soluble polymer polyvinylpyrrolidone. The above generator is
a heat recovery unit that recovers heat generated by the hydrogen engine;
6. The hydrogen supply system according to any one of claims 1 to 5, further comprising an inverter that converts the power generated by the power generation unit from direct current to alternating current. Using the hydrogen ions and electrons obtained by photolyzing water into oxygen, a formic acid generating device that coats the surface of a solid substrate with a mixture of titanium oxide fine particles, a pigment, and a viologen compound generates the above hydrogen ions, electrons, and the atmosphere. a formic acid production step of producing and storing formic acid by artificial photosynthesis from internal or exhaust carbon dioxide;
a formic acid decomposition step in which formic acid is decomposed into hydrogen and carbon dioxide in a deoxygenated environment at normal temperature and normal pressure with a catalyst obtained by dispersing platinum fine particles in a water-soluble polymer polyvinylpyrrolidone;
A power generation step of generating electric power by a power generation unit driven by a hydrogen engine driven by using hydrogen obtained by decomposition in the formic acid decomposition step as a fuel;
has
Hydrogen supply characterized by circulating carbon dioxide by supplying carbon dioxide obtained by decomposition in the formic acid decomposition step and obtained through the power generation step to the formic acid generation step without separating it from hydrogen. Method.

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