WO2014192188A1 - Water decomposition method and water decomposition device - Google Patents

Abstract

Provided are a water decomposition method and a water decomposition device, each of which enables the efficient decomposition of water. A reaction vessel (3) into which water is to be supplied is provided. The reaction vessel (3) is provided with a microwave irradiation means (4) and an ultraviolet ray irradiation means (5). In the reaction vessel (3), water is irradiated with a microwave by means of the microwave irradiation means (4) and is also irradiated with ultraviolet ray by means of the ultraviolet ray irradiation means (5). When water is irradiated with the microwave, each of a covalent bond and a hydrogen bond can be brought into an excited state by the action of the microwave. When water in the above-mentioned excited state is additionally irradiated with ultraviolet ray, a redox reaction occurs and consequently the covalent bond and the hydrogen bond are cleaved, resulted in the decomposition of water. Hydrogen and oxygen generated upon the decomposition of water are collected by a hydrogen collection means (6) and an oxygen collection means (7), respectively.

Description

Water splitting method and water splitting apparatus

The present invention relates to a water splitting method and a water splitting apparatus for splitting water into hydrogen and oxygen.

In recent years, from the viewpoint of energy saving based on problems such as global warming, technologies using hydrogen energy, such as cogeneration systems such as household fuel cell systems and fuel cell vehicles, have attracted attention.

As a technique for producing hydrogen used in such a technique using hydrogen energy, a method based on electrolysis of water is conventionally known (see, for example, Patent Document 1 and Patent Document 2).

JP 2010-280975 A JP 2006-118202 A

However, in the electrolysis of water as in Patent Document 1 and Patent Document 2 described above, the oxidation-reduction reaction occurs only around the electrode, and the range in which water is decomposed is limited. There is a problem that water is not decomposed efficiently because it is long and the amount of decomposition is small.

The present invention has been made in view of these points, and an object thereof is to provide a water splitting method and a water splitting apparatus capable of efficiently splitting water.

The water splitting method described in claim 1 is to split water into hydrogen and oxygen by irradiating water with microwaves and ultraviolet rays.

The water splitting method according to claim 2 is the water splitting method according to claim 1, wherein the water is irradiated with microwaves and ultraviolet rays in a state where the activation energy of the water to be decomposed is lowered by the photocatalyst. Is.

The water splitting method described in claim 3 uses the photocatalyst carrying a metal in the water splitting method described in claim 2.

The water splitting method described in claim 4 is the water splitting method according to any one of claims 1 to 3, wherein an electrolyte is added to water to be decomposed.

The water splitting method according to claim 5 is the water splitting method according to any one of claims 1 to 4, wherein the frequency of the microwave is set based on a redox potential of water to be decomposed. .

The water splitting method described in claim 6 is the water splitting method according to any one of claims 1 to 5, wherein oxygen generated by water splitting is converted into carbon dioxide by activated carbon.

The water splitting apparatus according to claim 7 irradiates the water in the reaction tank with a reaction tank to which water is supplied, microwave irradiation means for irradiating the water in the reaction tank with microwaves, and ultraviolet rays. An ultraviolet irradiation means and a recovery means for recovering at least hydrogen generated by the decomposition of water are provided.

The water splitting apparatus described in claim 8 is the water splitting apparatus described in claim 7, wherein a photocatalyst is provided on the inner surface of the reaction tank.

The water splitting device described in claim 9 is the water splitting device according to claim 8, wherein the photocatalyst carries a metal.

A water splitting device according to claim 10 is the water splitting device according to any one of claims 7 to 9, comprising an electrolyte supply means for adding an electrolyte to water to be decomposed.

A water splitting device according to claim 11 is the water splitting device according to any one of claims 7 to 10, further comprising a redox potential measuring means for measuring a redox potential of water, from a microwave irradiation means. The frequency of the irradiated microwave is set based on the redox potential measured by the redox potential measuring means.

A water splitting device according to claim 12 is the water splitting device according to any one of claims 7 to 11, wherein the recovery means includes a hydrogen recovery means for recovering hydrogen, and an oxygen recovery means for recovering oxygen. The activated carbon is supported on at least one of the photocatalyst and the oxygen recovery means.

According to the present invention, since water is irradiated with microwaves and ultraviolet rays are irradiated, an oxidation-reduction reaction can be caused in a wide range and water can be efficiently decomposed.

It is a block diagram which shows the structure of the water splitting device which concerns on the 1st Embodiment of this invention. FIG. 2 is an AA end view of FIG. 1. It is a perspective view which shows the photocatalyst in a water splitting device same as the above. It is a block diagram which shows the structure of the water splitting apparatus which concerns on the 2nd Embodiment of this invention. FIG. 5 is a BB end view of FIG. 4. It is a block diagram which shows the structure of the water splitting apparatus which concerns on the 3rd Embodiment of this invention. FIG. 7 is a CC end view of FIG. 6.

Hereinafter, the configuration of the first exemplary embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1 and FIG. 2, 1 is a water splitting device. This water splitting device 1 is a so-called vertical type, which splits water supplied from a water supply means 2 into hydrogen and oxygen, and these hydrogen and oxygen Recover. The water can be appropriately selected from, for example, tap water such as tap water and natural water.

Such a water splitting apparatus 1 includes a reaction tank 3 to which water supply means 2 is connected. The reaction tank 3 is provided with microwave irradiation means 4 for irradiating the water in the reaction tank 3 with microwaves. The reaction tank 3 is provided with ultraviolet irradiation means 5 for irradiating the water in the reaction tank 3 with ultraviolet rays. Further, the reaction tank 3 is provided with a hydrogen recovery means 6 and an oxygen recovery means 7 as recovery means for recovering hydrogen and oxygen generated by the decomposition of water. A photocatalyst 8 that reduces the activation energy of water in the reaction tank 3 is provided on the entire inner surface of the reaction tank 3.

In addition, the structure which can measure the oxidation reduction potential of the water decomposed | disassembled in the reaction tank 3 is provided in the reaction tank 3 and the water supply means 2 by providing the oxidation reduction potential measurement means which is not shown in figure.

The reaction tank 3 is a so-called oval shape having a cylindrical shape, and is a pressure vessel having a rounded rectangular shape in which both ends in the axial direction are arcuate in a plan view. The pressure resistance of the reaction tank 3 is preferably 10 Mpa or more based on heat generated during the decomposition of water and pressure due to water supply.

Further, the reaction vessel 3 preferably has an electrolyte supply means (not shown) for supplying an electrolyte such as carbonic acid in order to reduce the redox potential of the water to be decomposed.

In the reaction tank 3, as shown in FIG. 2, the ultraviolet irradiation means 5 is disposed on a substantially central axis in the reaction tank 3. Two microwave irradiation means 4 are arranged outside the ultraviolet irradiation means 5 in the reaction tank 3 so as to sandwich the ultraviolet irradiation means 5.

The microwave irradiation means 4 is, for example, a magnetron. This microwave irradiation means 4 is connected to a power source 11 and irradiates microwaves of a predetermined frequency. Note that the microwave frequency is selected in the range of 0.2 GHz to 5 GHz. The frequency of the microwave is usually set to 2.45 GHz, which is the same as that of a general microwave oven, for example, but is preferably set based on the redox potential of water measured by the redox potential measuring means. .

Further, the microwave irradiation means 4 is arranged so as to extend from one end portion in the axial direction of the reaction tank 3 to the other side, and serves as a ground side, and the other side in the axial direction of the reaction tank 3. And a microwave receiving electrode 13 arranged so as to extend from one end to the other side.

And the microwave irradiation means 4 radiates | emits a microwave toward the microwave receiving electrode 13 from the microwave radiation electrode 12 which is a ground side in the reaction tank 3. FIG. The microwave radiated from the microwave radiation electrode 12 is finally received by the microwave reception electrode 13 while diffusing into the entire reaction tank 3 toward the photocatalyst 8. The microwave irradiated from the microwave irradiation means 4 and diffused throughout the reaction tank 3 in this way generates plasma in water and dissociates the covalent bond and hydrogen bond of water molecules, thereby decomposing water. To promote.

The ultraviolet irradiation means 5 is, for example, an ultraviolet lamp, and in consideration of the pressure of water in the reaction tank 3, a protective layer having excellent heat resistance and pressure resistance such as quartz glass or quartz (not shown) is provided around the periphery. A configuration is preferred. In particular, quartz glass is preferable because it has a high ultraviolet transmittance and can emit ultraviolet rays efficiently.

The ultraviolet irradiation means 5 is connected to the power source 11 and irradiates ultraviolet rays having a wavelength selected from a range of 100 nm to 400 nm. The irradiated ultraviolet light diffuses toward the photocatalyst 8 in the reaction vessel 3.

Thus, the ultraviolet rays irradiated from the ultraviolet irradiation means 5 cause a redox reaction in the water in which the covalent bond and the hydrogen bond are dissociated by the microwave, and break the covalent bond and the hydrogen bond of the water molecule, Decomposes into hydrogen and oxygen.

The hydrogen recovery means 6 has a plurality of, for example, eight hydrogen permeation pipes 15 arranged on the circumference around the ultraviolet irradiation means 5 outside the microwave irradiation means 4 in the reaction tank 3. . A hydrogen recovery line 16 is connected to one end of each hydrogen permeation pipe 15.

The hydrogen permeable pipe 15 has a cylindrical pipe body 17 that is formed of a hydrogen permeable film made of, for example, an Nb + W + Mo alloy and is permeable to hydrogen. The space 18 inside the pipe body 17 communicates with the hydrogen recovery line 16. Then, hydrogen existing in the space 18 through the pipe body 17 is recovered from the space 18 through the hydrogen recovery line 16.

The oxygen recovery means 7 has a plurality of, for example, eight oxygen permeation pipes 21 arranged on the circumference around the ultraviolet irradiation means 5 outside the hydrogen permeation pipe 15 in the reaction tank 3. An oxygen recovery line 22 is connected to one end of each oxygen permeable pipe 21.

The oxygen permeable pipe 21 is formed of an oxygen permeable film made of, for example, oxygen permeable ceramics and has a cylindrical pipe body 23 that is permeable to oxygen. Further, the space portion 24 inside the pipe body 23 communicates with the oxygen recovery line 22. The oxygen present in the space portion 24 through the pipe body 23 is recovered from the space portion 24 through the oxygen recovery line 22.

The hydrogen recovery line 16 and the oxygen recovery line 22 are preferably connected to a suction means such as an aspirator (not shown) so that the hydrogen in the hydrogen permeation pipe 15 and the oxygen in the oxygen permeation pipe 21 can be aspirated.

The photocatalyst 8 is, for example, titanium oxide, and is continuously lined on the entire inner surface of the reaction tank 3. The photocatalyst 8 has a three-dimensional shape as shown in FIG. Specifically, the photocatalyst 8 has a substantially hexagonal pyramidal base portion 26 protruding from the inner surface of the reaction tank 3, and has a larger surface area than that of a flat surface, and contacts the water in the reaction tank 3. Large area. In addition, a projection 27 protruding from the base 26 is provided at the center of the base 26, and microwaves and ultraviolet rays are guided to the projection 27.

Next, the water splitting method in the first embodiment will be described.

When water is decomposed by the water splitting device 1, first, water is supplied from the water supply means 2 and the reaction tank 3 is filled with water. The water supply means 2 always supplies a predetermined amount of water into the reaction tank 3 even during the decomposition of the water.

Also, along with the supply of water, the electrolyte is supplied by an electrolyte supply means, and the electrolyte is added to the water in the reaction tank 3 to lower the redox potential of the water in the reaction tank 3.

The activation energy of the water supplied into the reaction vessel 3 is reduced by the photocatalyst 8 provided on the inner surface of the reaction vessel 3 and the added electrolyte.

Here, when decomposing water, it is important to give water more energy than the activation energy for decomposing hydrogen and oxygen to bring water molecules into a transition state.

Therefore, by reducing the activation energy of water in advance by the action of the photocatalyst 8 provided in the reaction tank 3 and the electrolyte added to the water in the reaction tank 3, the water is easily decomposed. .

In addition, since the photocatalyst 8 reduces the activation energy by coming into contact with water as a reactant, the surface area of the photocatalyst 8 can be reduced when the photocatalyst 8 is configured in a three-dimensional configuration as shown in FIG. The activation energy can be reduced more efficiently.

In this state where the activation energy of water is lowered, the microwave irradiation means 4 irradiates the water in the reaction tank 3 with microwaves, and the ultraviolet irradiation means 5 irradiates the water in the reaction tank 3 with ultraviolet rays. To do.

The microwave irradiation means 4 irradiates the microwave from the microwave radiation electrode 12 on the ground side toward the microwave reception electrode 13. Thus, the microwave radiated from the microwave radiation electrode 12 is finally received by the microwave reception electrode 13 while being diffused so as to be guided to the protrusion 27 of the photocatalyst 8.

In the reaction tank 3, the microwave diffuses toward the protrusion 27, so that the microwave is irradiated almost uniformly in the reaction tank 3, and plasma is generated in water in a wide area in the reaction tank 3, Bubbles are generated.

When plasma is generated in water in this way, the vibration causes hydrogen bonds between hydrogen atoms in water molecules and covalent bonds between hydrogen atoms and oxygen atoms to be dissociated. Become.

Here, when the water is decomposed by causing an oxidation-reduction reaction, it is important to give a potential higher than the oxidation-reduction potential of hydrogen and the oxidation-reduction potential of oxygen to the water to be decomposed.

That is, in water, electrons cannot move to hydrogen ions unless the negative electrode potential is negatively greater than the redox potential of hydrogen ions. In addition, electrons cannot move from oxygen ions unless the potential of the positive electrode is positively greater than the oxidation-reduction potential of oxygen ions.

Therefore, by irradiating with microwaves, water is given a potential higher than the redox potential of hydrogen ions and the redox potential of oxygen ions, and energy is added to the initial electrons in water to accelerate the initial electrons to make high-energy electrons. . In addition, when the high energy electrons collide with water molecules, hydrogen atoms, and oxygen atoms, energy is transferred between the high energy electrons and the water molecules, hydrogen atoms, and oxygen atoms. Then, the energy is exchanged by this energy transfer, and neutral molecules and atoms are ionized into ions and electrons to be in an excited state.

Therefore, by applying a potential higher than the oxidation-reduction potential of hydrogen ions and the oxidation-reduction potential of oxygen ions by microwaves, hydrogen ions and oxygen ions can exchange electrons, and water is easily decomposed by the action of ultraviolet rays. Become.

Moreover, since the redox potential of water can be lowered by adding an electrolyte to the water in the reaction vessel 3, water molecules can be efficiently excited by microwaves.

It should be noted that the components are slightly different depending on the water to be decomposed. For example, even when tap water is decomposed, the components are slightly different depending on the place where the tap water is obtained, and therefore the redox potential of the water is different. Therefore, the frequency of the microwave is preferably set based on the redox potentials of the hydrogen and oxygen of the water in consideration of the redox potential of the water to be decomposed.

Specifically, the oxidation-reduction potential of a specific substance in water can be obtained based on the Nernst equation. That is, E is an oxidation-reduction potential, E ₀ is a standard electrode potential, R is a gas constant (8.314 J / K · mol), T is an absolute temperature (K), and n is exchanged by an oxidation-reduction reaction. Assuming that the number of electrons (the number of mobile electrons), F is the Faraday constant, [ox] is the oxidation activity of the specific substance, and [red] is the reduction activity of the specific substance, E = E ₀ + (RT / nF) ln ([ox] / [red]).

Therefore, for the water to be decomposed, the above-mentioned elements are measured by the redox potential measuring means to calculate the redox potential of hydrogen and oxygen, and the microwave frequency is set so that the potential becomes larger than the redox potential of hydrogen and oxygen. It is preferable to set.

For reference, the oxidation-reduction potential of various waters in Japan and water in various places is in the range of about -390 mV to 773 mV.

UV light is called actinic radiation and has a chemical effect on the object to be irradiated and has the ability to promote redox reactions. When such ultraviolet rays are irradiated to water in which hydrogen bonds and covalent bonds are excited by microwave irradiation, an oxidation-reduction reaction occurs in the water, and the hydrogen bonds and covalent bonds are cut off. Is broken down into

Hydrogen generated by such water decomposition passes through the pipe body 17 of the hydrogen permeation pipe 15 and is sucked by an aspirator or the like connected to the hydrogen recovery line 16 and recovered from the space 18 to the hydrogen recovery line 16. Is done.

Further, oxygen generated by the decomposition of water passes through the pipe body 23 to the oxygen permeable pipe 21, is sucked by an aspirator connected to the oxygen recovery line 22, and is recovered from the space 24 to the oxygen recovery line 22. The

Next, the effect of the first embodiment will be described.

According to the first embodiment, the water in the reaction vessel 3 is irradiated with microwaves by the microwave irradiating means 4 and also irradiated with ultraviolet rays by the ultraviolet irradiating means 5, thereby hydrogen bonding and sharing by microwaves. The bond can be dissociated to bring the water molecule into an excited state, and ultraviolet light acts in this excited state to cause an oxidation-reduction reaction, thereby decomposing water into hydrogen and oxygen. Therefore, for example, since it is not decomposed via an electrode such as conventional electrolysis of water such as Patent Document 1 and Patent Document 2 described above, the place where the oxidation-reduction reaction occurs is not limited to the vicinity of the electrode. A redox reaction can occur in a wide range irradiated with waves and ultraviolet rays, and water can be efficiently decomposed.

In addition, since the photocatalyst 8 is provided in the reaction tank 3, the water can be irradiated with microwaves and ultraviolet rays in a state where the activation energy of the water to be decomposed is reduced by the photocatalyst 8. Can be disassembled.

Since this photocatalyst 8 has a configuration that protrudes three-dimensionally from the inner peripheral surface of the reaction vessel 3, the surface area of the photocatalyst 8 with respect to the water in the reaction vessel 3 can be increased compared to the case of a flat configuration, and thus more efficient. The activation energy can be reduced.

In addition, since the photocatalyst 8 has the protrusion 27, microwaves and ultraviolet rays are easily diffused in the reaction tank 3 so as to be guided to the protrusion 27. Therefore, the photocatalyst 8 is oxidized in the widest possible range of the entire reaction tank 3. A reduction reaction can occur and water can be efficiently decomposed.

Since the reaction tank 3 has an oval configuration, microwaves and ultraviolet rays are easily diffused and irradiated easily in the reaction tank 3, so that water can be efficiently decomposed.

Since the electrolyte supply means is provided in the reaction tank 3, the electrolyte can be added to the water to be decomposed. Therefore, the water can be efficiently decomposed by reducing the oxidation-reduction potential of the water by the electrolyte.

In addition, since a redox potential measuring means is provided, and a microwave frequency is set based on the redox potential of water measured by the redox potential measuring means, a microwave having a more appropriate frequency can be selected. It is possible to accurately bring hydrogen atoms and oxygen atoms into an excited state, and to efficiently decompose water.

Furthermore, by providing the hydrogen recovery means 6 and the oxygen recovery means 7 as recovery means, it is possible to accurately recover both hydrogen and oxygen generated by water decomposition.

In the first embodiment, the microwave irradiation means 4, the ultraviolet irradiation means 5, the hydrogen recovery means 6 and the oxygen recovery means 7 in the reaction tank 3 have the arrangement and number shown in FIG. The arrangement and number of the microwave irradiation means 4, the ultraviolet irradiation means 5, the hydrogen recovery means 6 and the oxygen recovery means 7 in the tank 3 are not limited to the arrangement of the first embodiment, and can be appropriately designed.

The reaction vessel 3 is configured as an oval pressure vessel. However, the reaction vessel 3 is not limited to such a configuration. The reaction vessel 3 may have any shape as long as it can decompose water by irradiation with microwaves and ultraviolet rays. May be used.

In addition, the reaction tank 3 has a configuration in which the photocatalyst 8 is provided on the inner surface. However, the present invention is not limited to such a configuration, and the photocatalyst 8 is provided as long as water can be decomposed by irradiation with microwaves and ultraviolet rays. You may make it the structure which is not carried out.

Furthermore, in the case of a configuration in which the photocatalyst 8 is provided on the inner peripheral surface of the reaction vessel 3, the photocatalyst 8 is not limited to a configuration having a three-dimensional base portion 26 and a projection portion 27, and for example, in a plate shape The photocatalyst may be provided. Further, when the photocatalyst 8 has a three-dimensional configuration, the shape of the base portion 26 is not limited to a substantially hexagonal pyramid shape, and may be any shape as long as the surface area can be increased.

The reaction tank 3 is provided with an electrolyte supply means and is configured to add an electrolyte to water to be decomposed. However, the present invention is not limited to such a configuration, and may be configured to not add an electrolyte.

Further, in the case of a configuration in which an electrolyte is added, the electrolyte is not limited to carbonic acid, and an aqueous solution of a metal compound such as potassium, calcium, or sodium may be used as the electrolyte.

The frequency of the microwave irradiation means 4 is preferably set based on the redox potential of water to be decomposed, but is not limited to the configuration for setting the microwave frequency in this way. In other words, microwaves bring hydrogen bonds and covalent bonds of water into a dissociated state, and ultimately decompose hydrogen and oxygen by the action of ultraviolet rays. It is not necessary to set based on the redox potential. Basically, any water can be excited by a microwave of 2.45 GHz which is a frequency of a general microwave oven.

The ultraviolet irradiation means 5 has a configuration using an ultraviolet lamp, but is not limited to such a configuration, and any unit that can irradiate ultraviolet rays in the reaction vessel 3 may be used.

Further, although the microwave irradiation means 4 and the ultraviolet irradiation means 5 are configured separately, the present invention is not limited to such a configuration, and the microwave irradiation means 4 and the ultraviolet irradiation means 5 may be integrated. Good.

The hydrogen recovery means 6 and the oxygen recovery means 7 are provided as recovery means, and both hydrogen and oxygen generated by the decomposition of water can be recovered. However, the present invention is not limited to such a configuration. May be configured so that at least hydrogen can be recovered.

Further, the hydrogen recovery means 6 is configured to recover hydrogen using the hydrogen permeation pipe 15 through which hydrogen can permeate. However, the hydrogen recovery means 6 is not limited to such a configuration, and can be appropriately designed as long as the configuration can recover hydrogen. It is.

Further, the oxygen recovery means 7 is configured to recover oxygen using the oxygen permeable pipe 21 through which oxygen can permeate. However, the oxygen recovery means 7 is not limited to such a configuration, and can be appropriately designed as long as the configuration can recover oxygen. It is.

Here, the water splitting device 1 is configured as a vertical type, but is not limited to such a configuration. For example, the horizontal type second shown in FIGS. The configuration of the embodiment may be adopted.

4 and 5, the horizontal water splitting device 31 is easy to uniformly irradiate microwaves and ultraviolet rays in the reaction tank 3, and easily recovers hydrogen and oxygen generated by water splitting. Microwave irradiation means 4, ultraviolet irradiation means 5, hydrogen permeation pipe 15 of hydrogen recovery means 6 and oxygen recovery pipe of oxygen recovery means 7 are arranged.

That is, the ultraviolet irradiation means 5 is arranged in the lower part of the oval reaction tank 3, and the microwave irradiation means 4 is arranged above it. Further, a plurality of, for example, nine oxygen permeable pipes 21 are arranged in an arc shape in the vicinity of the inner peripheral surface of the reaction tank 3, and a plurality of, for example, eight hydrogen permeable pipes 15 are arranged in an arc shape inside thereof.

And also in this 2nd Embodiment, an oxidation-reduction reaction can be caused in the wide range in the reaction tank 3 similarly to the said 1st Embodiment, and water can be decomposed | disassembled efficiently.

Next, a third embodiment will be described with reference to FIGS. In addition, about the structure and effect | action same as the said embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

As shown in FIGS. 6 and 7, in the water splitting device 41, a plurality of, for example, six oxygen permeable pipes 21 constituting the oxygen recovery means 7 outside the microwave irradiation means 4 are centered on the ultraviolet irradiation means 5. It is arranged on the circumference. Further, a plurality of, for example, 14 hydrogen permeable pipes 15 are arranged outside the oxygen permeable pipes 21 on the circumference centering on the ultraviolet irradiation means 5.

Further, palladium and strontium as metals are supported on the photocatalyst 8 provided on the inner side surface of the reaction tank 3, and a palladium supporting part 42 and a strontium supporting part 43 are formed.

These palladium and strontium are separately supported on one side of the width direction in the reaction tank 3 by half. That is, palladium is supported on the left half surface in the drawing, which is the water supply means 2 side, to form a palladium support portion 42, and strontium is present on the right half surface in the figure, which is the opposite side to the water supply means 2. A strontium supporting portion 43 is formed.

Here, strontium has an ionization tendency of 0.9V, whereas palladium has an ionization tendency of -2.89V.

Therefore, by supporting strontium and palladium half-sided in the reaction vessel 3, a potential difference is generated in the reaction vessel 3 based on the ionization tendency of strontium and palladium, and the water decomposition reaction can be promoted.

Therefore, the activation energy of water is reduced by the photocatalyst 8, and the water can be efficiently decomposed by irradiating the water with microwaves and ultraviolet rays in a state where a potential difference is generated by palladium and strontium.

In addition, it is preferable that the reaction tank 3 has a configuration in which activated carbon (not shown) is supported on the photocatalyst 8 and the outer surface of each oxygen permeable pipe 21.

Since the activated carbon is supported on the photocatalyst 8 and the oxygen permeable pipe 21, at least a part of oxygen generated by the decomposition of water is changed to carbon dioxide by the photooxidation power of the photocatalyst 8 and the action of the activated carbon.

And since carbon dioxide is easier to dissolve and stabilize in water than oxygen, it can prevent oxygen and hydrogen once decomposed by the action of microwaves and ultraviolet rays from recombining to become water, Heat generation can be prevented.

In addition, carbon dioxide generated by the action of activated carbon acts as carbon dioxide as an electrolyte in the reaction tank 3, and can reduce the redox potential of water in the reaction tank 3.

Note that oxygen that has not been changed to carbon dioxide is recovered by the oxygen recovery means 7.

In the third embodiment, palladium and strontium are used as the metal supported on the photocatalyst 8. However, the present invention is not limited to such a configuration, and any metal that can generate a potential difference in the reaction vessel 3 is used as appropriate. You can choose.

Also, the location of the metal can be determined as appropriate. For example, in the case of a horizontal type configuration as shown in FIGS. 4 and 5, strontium is supported on the photocatalyst 8 located on the upper half in the vertical direction, and the lower side is arranged. A configuration in which palladium is supported on the photocatalyst 8 located on one side can be employed.

Furthermore, the present invention is not limited to the configuration in which the metal is supported on the photocatalyst 8 on the entire inner peripheral surface of the reaction tank 3, and for example, a configuration in which the metal is supported on only a part may be adopted.

Moreover, when providing activated carbon, it is not limited to the structure in which the active substance was provided in both the photocatalyst 8 and the oxygen collection | recovery means 7, It is set as the structure by which activated carbon was provided only in one of the photocatalyst 8 or the oxygen collection | recovery means 7. May be.

DESCRIPTION OF SYMBOLS 1 Water splitting device 3 Reaction tank 4 Microwave irradiation means 5 Ultraviolet irradiation means 6 Hydrogen recovery means as recovery means 7 Oxygen recovery means as recovery means 8 Photocatalyst 31 Water decomposition apparatus 41 Water decomposition apparatus

Claims (12)

Irradiate water with microwaves and ultraviolet rays,
A water splitting method characterized by splitting water into hydrogen and oxygen. The water splitting method according to claim 1, wherein the water is irradiated with microwaves and ultraviolet rays in a state where the activation energy of the water to be decomposed is lowered by the photocatalyst. The water splitting method according to claim 2, wherein a photocatalyst on which a metal is supported is used. The water decomposition method according to any one of claims 1 to 3, wherein an electrolyte is added to water to be decomposed. The water decomposition method according to any one of claims 1 to 4, wherein the frequency of the microwave is set based on a redox potential of water to be decomposed. The water decomposition method according to any one of claims 1 to 5, wherein oxygen generated by the decomposition of water is converted into carbon dioxide by activated carbon. A reaction vessel to which water is supplied;
Microwave irradiation means for irradiating the water in the reaction vessel with microwaves;
Ultraviolet irradiation means for irradiating the water in the reaction tank with ultraviolet rays;
A water splitting apparatus comprising: a recovery means for recovering at least hydrogen generated by water splitting. The water splitting device according to claim 7, wherein a photocatalyst is provided on an inner surface of the reaction tank. The water splitting device according to claim 8, wherein the photocatalyst carries a metal. The water splitting device according to any one of claims 7 to 9, further comprising electrolyte supply means for adding an electrolyte to water to be decomposed. Provided with a redox potential measuring means for measuring the redox potential of water,
11. The water according to claim 7, wherein the frequency of the microwave irradiated from the microwave irradiation unit is set based on the oxidation-reduction potential measured by the oxidation-reduction potential measurement unit. Disassembly equipment. The recovery means has a hydrogen recovery means for recovering hydrogen and an oxygen recovery means for recovering oxygen,
The water splitting device according to any one of claims 7 to 11, wherein activated carbon is supported on at least one of the photocatalyst and the oxygen recovery means.

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