JP6787826B2 - Hydrogen generation cell, concentrating hydrogen generation cell and hydrogen production equipment - Google Patents

Description

The present disclosure relates to a hydrogen generation cell, a concentrating hydrogen generation cell, and a hydrogen production apparatus.

In recent years, as a solution to problems such as global warming due to an increase in carbon dioxide due to the consumption of fossil fuels, the development of clean renewable energy that does not emit carbon dioxide instead of fossil fuels has become more important.

Solar energy, which is one of the renewable energies, does not have to be depleted and can contribute to the reduction of greenhouse gases. In recent years, fuel cells have begun to spread and are expected to play a leading role in the hydrogen energy society. Most of the hydrogen currently produced uses fossil fuels as a raw material, and there are problems in terms of fundamental fossil fuel reduction.

Under these circumstances, the form of seeking primary energy from sunlight and supporting secondary energy with hydrogen is one of the ideal clean energy systems, and its establishment is urgently needed.

For example, as one of the methods for converting solar energy into chemical energy, it has been proposed to utilize a two-step water splitting reaction that occurs when a ceramic member such as Celia (CeO ₂ ) is used as a reaction system carrier. (See, for example, Patent Document 1).

This is because in the first step, the ceramic member which is the reaction system carrier is heated to 1400 to 1800 ° C. using solar energy, and the ceramic member is reduced to generate oxygen, and then in the second step. The reduced ceramic member is reacted with water at 300 to 1200 ° C. to oxidize the reduced ceramic member to generate hydrogen.

JP-A-2009-263165

However, at this stage, in reality, there is no example in which hydrogen is directly generated from water vapor by directly heating a single reaction system composed of ceramic members using heat from solar energy. ..

The present disclosure has been made in view of the above problems, and an object of the present invention is to provide a hydrogen generation cell, a concentrating hydrogen generation cell, and a hydrogen production apparatus capable of efficiently generating hydrogen from water vapor. is there.

Hydrogen generation cell of the present disclosure, the ceramic particles, the complex of the metallic particles, a hydrogen generating cell that provides in a housing which is filled with gas, the ceramic particles, La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O _3-δ or Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-δ , and the metal particles are Ni. Coating particles containing Pt as a main component are supported on the surface of the base material particles as the main component, and the coating particles cover the entire surface of the base material particles or the coating particles. Is either attached in a partially separated state so as to form irregularities on the surface of the base material particles .

The concentrating hydrogen generation cell of the present disclosure contains a hydrogen generation unit composed of the above hydrogen generation cell and La _0.8 Sr _0.2 MnO ₃ as main components, and 0.5 mol of Fe at the Mn site. It is composed of a light absorbing portion composed of a substituted perovskite material and borosilicate glass .

The hydrogen production apparatus of the present disclosure includes a reaction unit that undergoes an oxidation / reduction reaction by receiving solar energy, a water vapor supply unit that supplies water to the reaction unit, and a recovery unit that recovers hydrogen gas generated from the reaction unit. The above-mentioned concentrating hydrogen generation cell is installed in the reaction unit.

According to the present disclosure, hydrogen can be efficiently generated from water vapor.

It is sectional drawing which shows typically one Embodiment of the hydrogen generation cell of this disclosure. It is sectional drawing which shows the other aspect of a metal particle. It is sectional drawing which shows typically one Embodiment of the condensing type hydrogen generation cell of this disclosure. (A) is a perspective view showing the structure of the condensing type hydrogen generation cell of this embodiment in which the hydrogen generation part is arranged inside the light absorption part, and (b) is the X-ray of (a). It is an X-ray sectional view. It is sectional drawing which shows typically the hydrogen production apparatus of this embodiment.

FIG. 1 is a cross-sectional view schematically showing an embodiment of the hydrogen generation cell of the present disclosure. The hydrogen generation cell A of the present embodiment is composed of a composite 5 of ceramic particles 1 and metal particles 3. Further, the complex 5 is provided in a housing 7 filled with gas.

In this case, the composition formula of the ceramic particle 1 is AXO _{3 ± δ} (however, 0 ≦ δ ≦ 1, A: at least one element among rare earth element, alkaline earth element, and alkali metal element, X: transition. It is a composite metal oxide represented by at least one of a metal element and a metalloid element, O: oxygen). On the other hand, the metal particles 3 contain at least one element of Rh, Ru, Pd, Pt, Ni, Co and Fe as a main component. Here, the main component means a case where the element is contained in an amount of 90% by mass or more.

When the complex 5 is placed in a housing 7 having a space 9 filled with gas (air) and the complex 5 is brought into contact with water vapor, as shown in FIG. 1, water vapor (H ₂ O) Decomposes into hydrogen (H ₂ ) and oxygen (O ₂ ). In this case, oxygen (O ₂ ) decomposed from water vapor (H ₂ O) moves to the inside of the ceramic particle 1 as an anion represented as O ^2- , and once exists in the ceramic particle 1. .. On the other hand, hydrogen (H ₂ ) is separated from the complex 5 and diffuses into the space 9 of the housing 7.

According to the hydrogen generation cell A of the present embodiment, the decomposition reaction of water vapor (H ₂ O) in a state where water vapor (H ₂ O) is present as a gas other than air in the space 9 filled with air. Can generate hydrogen (H ₂ ). In the case of the present embodiment, since there is no liquid such as water around the complex 5, the amount of water vapor in contact with the surface of the complex 5 can be significantly increased. As a result, the efficiency of hydrogen (H ₂ ) production can be increased.

In this case, the ceramic particles 1 include a La-based composite metal oxide containing lanthanum iron acid as the main phase and containing strontium and cobalt, or a Ba-based composite metal oxide containing barium ferrate as the main phase and containing strontium and cobalt. good.

The composition represented by the molar ratio of the La-based composite metal oxide is La = 0.5 to 0.7, Sr.
= 0.3 to 0.5, Co = 0.1 to 0.3, Fe = 0.7 to 0.9, O = 3 ± 0.1 to 0.9 are preferable. On the other hand, the composition represented by the molar ratio of the Ba-based composite metal oxide is Ba = 0.4 to 0.6, Sr = 0.4 to 0.6, Co = 0.7 to 1.0, Fe. = 0.1 to 0.3 and O = 3 ± 0.1 to 0.9 are preferable.

Here, the principal component means, for example, a crystal phase that appears as a main peak when the ceramic particles 1 are identified by X-ray diffraction.

FIG. 2 is a schematic cross-sectional view showing another aspect of the metal particles. As the metal particles 3, those containing at least one element of the above-mentioned Rh, Ru, Pd, Pt, Ni, Co and Fe as a main component alone may be used, but in terms of cost and metal particles From the viewpoint of corrosion resistance of 3, at least one selected from the group of Rh, Ru, Pd and Pt is placed on the surface of the base metal particles 3a containing at least one base metal as a main component selected from the group of Ni, Co and Fe. It is preferable that the composite particles are supported by the coating particles 3b containing the noble metal as a main component. In this case, the coated particles 3b may be in a state of covering the entire surface of the base material particles 3a, but from the viewpoint that the specific surface area of the metal particles 3 can be improved, the surface of the base material particles 3a is formed with irregularities. , It is good that they are attached in a partially separated state.

Next, the concentrating hydrogen generation cell of the present embodiment will be described. FIG. 3 is a cross-sectional view schematically showing an embodiment of the concentrating hydrogen generation cell of the present disclosure. The concentrating hydrogen generation cell B of the present embodiment is composed of a hydrogen generation unit 11 and a light absorption unit 13. In this case, the hydrogen generating unit 11 and the light absorbing unit 13 are in contact with each other on the main surfaces. Here, the main surface is the surface having the largest area when the hydrogen generating unit 11 and the light absorbing unit 13 have a plurality of flat surfaces.

The hydrogen generation unit 11 is formed by the above-mentioned hydrogen generation cell A. The hydrogen generation unit 11 has a structure in which the composite 5 composed of the ceramic particles 1 and the metal particles 3 is sintered in a porous state so as to have a plurality of voids 14.

Also in the condensing type hydrogen generation cell B, the hydrogen generation unit 11 and the light absorption unit 13 are both installed in the housing 7 filled with gas.

According to the concentrating hydrogen generation cell B of the present embodiment, since the light absorption unit 13 is attached to the hydrogen generation unit 11, the efficiency of converting solar energy into heat is increased, and the hydrogen generation unit 11 The temperature can be higher. As a result, the rate of decomposition reaction of water vapor (H ₂ O) is increased, and the efficiency of hydrogen (H ₂ ) production can be further increased.

In this case, the concentrating hydrogen generation cell B has high light transmission because the medium existing inside the housing 7 is air. Therefore, the condensing hydrogen generation cell B installed inside the housing 7 can receive light in a state where the light attenuation rate is low. As a result, it is possible to increase the heat generation efficiency of the light absorption unit 13 as well as the hydrogen (H ₂ ) production efficiency of the hydrogen generation unit 11.

The light absorption unit 13 is preferably formed of a ceramic composite having a plurality of composite oxide particles 13b having a composition different from that of the ceramics 13a in the ceramics 13a having a porosity of 5% or less. In this case, as the composite oxide particles 13b, a ceramic material exhibiting positive resistance temperature characteristics is suitable. Since the composite oxide particles 13b exhibit the same resistance temperature characteristics as the metal, the composite oxide particles 13b have carriers (electrons) similar to electrons. Therefore, the composite oxide particles 13b exhibit a high surface plasmon effect due to carriers (electrons). As a result, the entire light absorbing unit 13 generates heat, and high heat generation efficiency can be obtained.

Here, as the material of the composite oxide particles 13b, a perovskite-type ceramic material represented as ABO ₃ is suitable. For example, the A site of ABO ₃ contains a rare earth element, while the B site contains a transition metal element, and the composite oxide particles 13b contain a small amount of an element having a valence different from that of the A site and the B site element. Things are good. For example, a material in which the A site of ABO ₃ is lanthanum (La) and the B site is manganese (Mn), which contains a trace amount of Sr, can be mentioned as a suitable example. For example, a composite oxide represented as La _1-x Sr _x MnO _{3 + δ} (x = 0.01 to 0.9, δ is arbitrary) is typical. In this case, the size (average particle size) of the composite oxide particles 13b is preferably fine, and is preferably 5 to 100 nm from the viewpoint of enhancing the surface plasmon effect.

As the ceramics 13a, low thermal expansion glass containing silicon oxide as a main component is suitable in that cracks and the like are unlikely to occur, and light transmission and heat resistance are excellent. In this case, the ceramic 13a preferably has a color brightness of 5 or more in the lightness display distinguished by the Munsell color system. Further, the coefficient of thermal expansion in the state where the ceramics 13a contains the composite oxide particles 13b (ceramic composite) is preferably 9 × 10 ^-6 / ° C. or less. When the coefficient of thermal expansion of the ceramic composite is 9 × 10 ^-6 / ° C. or less, the thermal shock resistance is enhanced, and the light absorbing portion 13 having a long life can be formed.

Further, from the viewpoint that the surface plasmon effect of the composite oxide particles 13b can be enhanced, the ratio of the composite oxide particles 13b contained in the ceramic composite is preferably 10 to 80% by volume.

The ratio of the composite oxide particles 13b constituting the light absorption unit 13 is determined by using an electron microscope and an analyzer (EPMA) attached to the cross section of the ceramic composite. For example, the ceramic composite is polished to expose the composite oxide particles 13b, and a predetermined region in which 30 to 100 composite oxide particles 13b existing in the cross section are contained is designated. Next, the area of this region and the total area of the composite oxide particles 13b existing in this region are obtained, and the total area of the composite oxide particles 13b with respect to the area of the region is obtained. The area ratio thus obtained is considered as the volume ratio. Whether or not the composite oxide particles 13b exist in the ceramics 1 in an isolated state as a single particle is also determined by counting the number from the above observation.

FIG. 4A is a perspective view showing another aspect of the concentrating hydrogen generating cell of the present embodiment, showing a configuration in which the hydrogen generating portion is arranged inside the light absorbing portion. (B) is a cross-sectional view taken along line XX of (a). Although the housing 7 is not drawn for the concentrating hydrogen generation cell shown in FIG. 4, the condensing hydrogen generation cell also has the same housing 7 as the condensing hydrogen generation cell shown in FIG. It will be installed inside.

In the concentrating hydrogen generation cell C shown in FIGS. 4A and 4B, when the light absorption unit 13 receives sunlight, the light absorption unit 13 and the hydrogen generation unit 11 are heated to a high temperature state. When water vapor is introduced into the hydrogen generation unit 11 in this state, hydrogen is generated in the hydrogen generation unit 11. The generated hydrogen is recovered, for example, from the opposite side of the end where water vapor is introduced, as shown in FIG. 4 (b).

In the case of the concentrating hydrogen generation cell C shown in FIGS. 4 (a) and 4 (b), since the columnar hydrogen generation unit 11 has a structure surrounded by the cylindrical light absorption unit 13, the light absorption unit 13 Is a concentrating hydrogen generating cell C having a high condensing property and a hydrogen generating unit 11 having a small heat loss due to radiation.

FIG. 5 is a cross-sectional view schematically showing the hydrogen production apparatus of the present embodiment. The hydrogen production apparatus D of the present embodiment includes a reaction unit 21 that receives solar energy to cause an oxidation / reduction reaction, a water vapor supply unit 23 that supplies water vapor to the reaction unit 21, and hydrogen gas or hydrogen gas generated from the reaction unit 21. It is provided with a recovery unit 25 for recovering oxygen gas. In this case, the above-mentioned concentrating hydrogen generation cell C is installed in the reaction unit 21. Further, the reaction unit 21 is also installed in the housing 7 using air as a medium in this case as well. In the hydrogen production apparatus D shown in FIG. 5, decompression pumps 31a and 31b are installed between the hydrogen separation module 27 and the recovery unit 25 and on the recovery unit 25 side of the housing 7.

In the hydrogen production apparatus D, when the light absorption unit 13 constituting the reaction unit 21 absorbs sunlight, the hydrogen generation unit 11 becomes a high temperature state together with the light absorption unit 13. At this time, when water vapor (H ₂ O) is passed through the hydrogen generating unit 11 constituting the reaction unit 21, hydrogen gas is generated inside the hydrogen generating unit 11. In this way, according to the hydrogen production apparatus of the present embodiment, it is possible to absorb heat from sunlight and efficiently generate hydrogen.

Here, as shown in FIG. 5, the reaction unit 21 is preferably housed in the housing 7 in a decompressed state. As a result, it is possible to prevent the heat generated by the light absorbing unit 13 from moving to the outside world other than the reaction unit 21. In this way, the heat stored in the light absorption unit 13 can be efficiently supplied to the hydrogen generation unit 11.

In the hydrogen production apparatus D of the present embodiment, the hydrogen separation module 27 is installed between the reaction unit 21 and the recovery unit 25. This makes it possible to recover hydrogen moving from the reaction unit 21 to the recovery unit 25 with higher purity.

As the hydrogen separation module 27, for example, a configuration in which a porous ceramic tube 27a is installed in a glass tube 27b can be mentioned as an example.

Further, it is preferable to install the light collecting plate 29 in the housing 7. As a result, sunlight can be applied to the back side of the reaction unit 21 on the side opposite to the incident side of sunlight. In this way, in the reaction unit 21, the area of the portion where the efficiency of the hydrogen production reaction is low can be reduced. As a result, the hydrogen production efficiency can be increased.

Hereinafter, a hydrogen production apparatus was manufactured, and the amount of hydrogen produced was measured. First, as ceramic particles for forming a hydrogen generation cell, La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O _3-δ and Ba _0.5 Sr _0.5 Co _0.8 Fe _{0. .2} O _3-δ was prepared. Two types of metal particles were prepared: a case of Pt alone and a case of a composite metal using Ni as a base particle and Pt as a coating particle. For the light absorbing portion, a perovskite material containing La _0.8 Sr _0.2 MnO ₃ as a main component and 0.5 mol of Fe substituted at the Mn site was used.

Next, the prepared ceramic particles and metal particles were mixed using a ball mill to prepare a molded product, which was sintered at 1150 ° C. in an air atmosphere to prepare a columnar hydrogen generation cell.

The light absorption unit was prepared by mixing borosilicate glass and the above-mentioned perovskite material to prepare a cylindrical molded product, which was sintered in the air at a temperature of 1400 ° C. The open porosity of the prepared light absorbing part was 4.5%.

Next, the light absorption unit and the hydrogen generation unit were joined by a ceramic bond to prepare a concentrating hydrogen generation cell.

Further, a box-shaped container made of SUS304 equipped with a quartz glass window was prepared as a housing, and a hydrogen production apparatus having the configuration shown in FIG. 5 was manufactured.

Next, a concentrating hydrogen generation cell was mounted in the housing, a hydrogen production test was conducted, and the amount of hydrogen produced was evaluated.

The amount of hydrogen produced was measured by installing a gas chromatograph device in the recovery section of the hydrogen production device. In this case, the hydrogen production apparatus is set to a condition in which the inside of the housing is depressurized and the sunlight is received in a state of 1 SUN. The number of irradiations of sunlight was 10 cycles.

As a result of the test, the sample No. in which the metal particles were supported on the ceramic particles. 1 (metal particles: Pt) and sample No. In the hydrogen generation cell of 2 (metal particles using Ni as a base particle and Pt as a coating particle), the amounts of hydrogen produced were 0.4 ml / g and 1.1 ml / g, respectively, but hydrogen. Sample No. in which the generation cell was prepared only with ceramic particles. In No. 3, the amount of hydrogen produced was 0.01 ml / g or less.

1 ... Ceramic particles 3 ... Metal particles 3a ... Base particles 3b ... Coating particles 5 ... Composite 7 ... Housing 9 ... Space 11 ... -Hydrogen generation unit 13 ... Light absorption unit 21 ... Reaction unit 23 ... Steam supply unit 25 ... Recovery unit A ... Hydrogen generation cells B, C ... Concentrating hydrogen generation Cell D ... Hydrogen production equipment

Claims (5)

Se and ceramic particles, the complex of the metallic particles, a hydrogen generating cell that provides in a housing which is filled with a gas,
The ceramic particles are La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O _3-δ or Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-δ .
The metal particles are formed by supporting coated particles containing Pt as a main component on the surface of base material particles containing Ni as a main component.
Whether the coating particles cover the entire surface of the base material particles
Alternatively, the coating particles are either attached in a partially separated state so as to form irregularities on the surface of the base material particles, or are hydrogen generation cells. A perovskite material containing 0.5 mol of Fe in Mn sites and a perovskite material containing La _0.8 Sr _0.2 MnO ₃ as a main component and a hydrogen silicate glass composed of the hydrogen generation cell according to claim 1. Light absorber consisting of
Concentrating hydrogen generation cell composed of. The concentrating hydrogen generation according to claim 2 , wherein the light absorbing portion is a ceramic composite having a plurality of composite oxide particles having a composition different from that of the ceramics in a ceramic having an open porosity of 5% or less. cell. The concentrating hydrogen generation cell according to claim 2 or 3 , wherein both the hydrogen generating section and the light absorbing section have a columnar shape, and the hydrogen generating section is arranged in the light absorbing section. The reaction unit is provided with a reaction unit that receives solar energy to cause an oxidation / reduction reaction, a water vapor supply unit that supplies water to the reaction unit, and a recovery unit that recovers hydrogen gas generated from the reaction unit. A hydrogen production apparatus according to any one of claims 2 to 4 , wherein the concentrating hydrogen generation cell is installed.

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