JP4959398B2 - Liquid core for fuel cell - Google Patents

Description

The present invention relates to a liquid absorbent core for a fuel cell for absorbing a plurality of liquids in the fuel cell .

  As a liquid absorbent core for absorbing a plurality of liquids having different surface tension and specific gravity, such as liquid fuel and water in a fuel cell, or a two-liquid reactive liquid in a drug evaporator such as a fragrance or insecticide, A porous body having a continuous air hole therein is known.

For example, the fuel cell of Patent Document 1 describes a Ni porous body for supplying a mixed liquid of methanol and water as a liquid fuel to a fuel electrode of a methanol cell. In this fuel cell, the mixed liquid moves by capillary action in the continuous air hole inside the porous body.
JP-A-6-188008

  However, in the Ni porous body of the fuel cell described in Patent Document 1, alcohol and water are reacted in advance to extract hydrogen gas (hereinafter referred to as reforming), but at this time, there is no balance between the concentration of alcohol and water. Some of the alcohol and the alcohol incompletely react to generate carbon, which becomes a residue and clogs the inside of the porous body.

  Not only in the case of alcohol and water in such fuel cells, but in some drug evaporators used for fragrances and insecticides, when two liquid reactive liquids are absorbed and reacted, transpiration If there is a reaction such as accumulation of residues before the reaction inside the passage, there is a limit to the use of the liquid absorbent core which can pass the mixed liquid through only one passage.

The liquid absorbent core for a fuel cell of the present invention has one surface and the other surface opposite to the liquid absorbent core, and is a dense liquid-absorbing portion made of porous ceramics and partitioning the liquid-absorbing portion from one surface to the other surface. and a partition wall made of quality material, Ri average Do porosity different with at least one other portion liquid-absorbing portion of the partial liquid absorbing portions partitioned by the partition wall portion, the average porosity of a different set of In the partial liquid absorption part, one partial liquid absorption part absorbs alcohol, and the other partial liquid absorption part absorbs water .

  Furthermore, the average porosity of the said partial liquid absorption part is 20 to 60%, It is characterized by the above-mentioned.

  Furthermore, the cross-sectional shape parallel to the one surface or the other surface of the partition wall is radial or concentric.

  Furthermore, the thermal conductivity of the liquid absorption part is 3 W / (m · K) or more.

  Furthermore, the porous ceramic is characterized by containing silicon carbide as a main component.

  Furthermore, the partition wall is characterized by containing a metal as a main component.

ADVANTAGE OF THE INVENTION According to this invention, about several types of liquid from which surface tension and specific gravity differ, it can be set as the liquid absorption core for fuel cells which can absorb liquid individually by controlling the liquid absorption amount to a predetermined range, respectively .

In the fuel cell , the amount of alcohol and water absorbed can be controlled within the specified ranges, and only the required amount can be absorbed individually, eliminating the possibility of unreacted liquid becoming a residue and decreasing the porosity. Can do.

  Moreover, since the thermal conductivity of the liquid absorbent core is increased and the entire liquid absorbent core can be heated more uniformly, it is possible to particularly prevent a decrease in the average porosity of the liquid absorbent part due to the modification.

  Moreover, since the thermal shock resistance of the partition wall can be increased, cracking of the partition wall can be reduced even when the absorbent core is heated and cooled.

  Hereinafter, embodiments of the liquid absorbent core of the present invention will be described.

  FIG. 1A is a perspective view showing a liquid absorbent core of the present invention, and FIG. 1B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 2A is a perspective view showing the liquid absorbent core of the present invention, and FIG. 2B is a cross-sectional view taken along line B-B ′ of FIG. FIG. 3A is a perspective view showing the liquid absorbent core of the present invention, and FIG. 3B is a cross-sectional view taken along line C-C ′ of FIG. FIG. 4A is a perspective view showing the liquid absorbent core of the present invention, and FIG. 4B is a cross-sectional view taken along the line D-D ′ in FIG.

  The liquid absorbent core 1 according to the present invention includes first and second partial liquid absorbent parts 2a and 2b made of porous ceramics (the first and second partial liquid absorbent parts 2a and 2b are combined to form a liquid absorbent part 2. )), The liquid absorption part 2 is partitioned by a dense partition wall part 3, and the liquid absorption core 2 in which the average porosity of each of the partial liquid absorption parts of the liquid absorption part 2 is different. By doing so, for example, the liquid absorption amount of the liquid (not shown) made of alcohol and the liquid absorption amount of water (not shown) are controlled within a predetermined range, respectively, and the liquid absorption that can be simultaneously absorbed from the respective partial liquid absorption portions 2a and 2b The core 1 can be obtained.

  Alcohol is absorbed from the one surface 5a side of the second partial liquid absorption portion 2b, and can move to the other surface 5b side through the continuous air hole in the second partial liquid absorption portion 2b. Water is absorbed from the one surface 6a side of the first partial liquid absorption part 2a, and has a structure that can move to the other surface 6b side through the continuous air vent in the first partial liquid absorption part 2a. Although not shown in FIGS. 1-4, the side wall 7 of the first partial liquid absorption part 2a is provided with a dense wall so that water does not evaporate.

The alcohol and water moved to the other ends 5b and 6b are heated and vaporized to be reformed. For example, when methanol is used as the alcohol, the reforming reaction is represented by CH ₃ OH + H ₂ O → 3H ₂ + CO ₂ . If methanol and water are absorbed and vaporized in the same number of moles, hydrogen gas and carbon dioxide can be generated using a catalyst. Here, if the methanol is excessive, the carbon residue generated from the unreacted methanol adheres to the inside of the porous body, thereby reducing the porosity. Therefore, the average porosity is set so that liquid can be absorbed from the first and second partial liquid absorbing parts 2a and 2b and vaporized so that the molar ratio of methanol and water is as much as possible.

  Here, since the amount of liquid absorption also changes depending on the cross-sectional areas of the first and second partial liquid absorption parts 2a and 2b in the direction perpendicular to the longitudinal direction of the partition wall 3, the first and second partial liquid absorption parts By setting the average porosity of each of 2a and 2b and the cross-sectional areas of the first and second partial liquid-absorbing parts 2a and 2b within a predetermined range, the respective liquid-absorbing amounts of alcohol and water can be equal to You can be close to this.

  Here, the term “dense” refers to a state where there is no continuous ventilation hole and capillary action does not occur.

  In the liquid absorbent core 1, it is important that the average porosity of the first and second partial liquid absorbent parts 2a and 2b is different. The reason for this is that if the cross-sectional area (the cross-sectional area in the direction perpendicular to the partition wall) of the first and second partial liquid-absorbing parts 2a and 2b is set to a predetermined value, the liquid is absorbed from one surface 5a and 6a. This is because it is difficult to control the amount of movement of alcohol and water vaporized on the side of the direction 5b, 6b per hour. The reason why it is difficult is considered that alcohol and water have different boiling points, different capillary forces, and different thermal conductivities.

  Furthermore, it is preferable that it is the liquid absorption core 1 whose average porosity of the liquid absorption part 2 is 20 to 60%. As a result, a sufficient amount of continuous air holes can be formed in the liquid absorption part 2 and the liquid can be sufficiently absorbed by utilizing the capillary force. It is possible to make the liquid absorption core easier to control within a predetermined range. The unit of the average porosity here means volume%. If the average porosity is higher than 20%, a sufficient amount of continuous air holes can be formed in the first and second partial liquid absorbing portions 2a and 2b, and it becomes easy to absorb alcohol and water. If the average porosity is less than 60%, the capillary force becomes strong and it becomes easy to absorb alcohol and water. Particularly, in order to have a sufficient amount of continuous air holes and to absorb the liquid by increasing the capillary force, the average porosity of the first and second partial liquid absorbing portions 2a and 2b is in the range of 30 to 50%. It is preferable that

  The structure of the liquid absorbent core 1 is not limited to the structure shown in FIGS. 1 to 4, but the cross-sectional shape parallel to one surface or the other surface of the partition wall 3 is concentric as shown in FIG. Or it is preferable that it is radial as shown in FIG. Accordingly, for example, alcohol and water are absorbed from one surface 5a, 6a of the liquid absorbent core 1 and alcohol and water are vaporized from the other surface 5b, 6b, so that the liquid absorbent core 1 is modified for the purpose of modifying the vaporized alcohol. Since each partial liquid absorption part 2a, 2b divided by the partition 3 is heated uniformly when heating, alcohol and water can be vaporized almost completely. For this reason, at the time of reforming, alcohol hardly becomes a carbon component, and the continuous vent hole of the liquid absorbing part 2 is not easily blocked, so that the possibility that the porosity of the partial liquid absorbing parts 2a and 2b is lowered can be eliminated.

  The partition wall 3 is provided here because when the liquid absorption part 2 has a non-uniform temperature distribution, vaporization becomes unstable in the surface direction. Therefore, by separating the partition part 3, the other partial liquid absorption parts 2 a, Prevents thermodynamic effects on 2b.

  By using a liquid absorbent core having a thermal conductivity of 3 W / (m · K) or more, the liquid absorbent core has a higher thermal conductivity and can heat the entire liquid absorbent core more uniformly. In particular, it is possible to prevent a decrease in the average porosity of the liquid absorption part due to the modification.

  The liquid absorbing part 2 is preferably made of porous ceramics mainly composed of any of alumina, mullite, zirconia, silicon nitride, and silicon carbide. In particular, the liquid absorption part 2 is preferably a liquid absorption core 1 mainly composed of silicon carbide. By using silicon carbide as the main component of the liquid absorption part 2, it is possible to make the liquid absorption core 1 in which carbon residue hardly adheres when the fuel is reformed, so that the average porosity changes with the reformation. It can be set as the difficult liquid absorption core 1. FIG.

  Since the partition wall 3 is made of the liquid-absorbing core 1 formed of metal, the thermal shock resistance of the partition wall 3 can be improved, so that the partition wall 3 is cracked even when the liquid-absorbing core 1 is heated and cooled. Can be reduced.

  In the above embodiment, the case where alcohol is absorbed from the second partial liquid absorption part 2b and water is absorbed from the first partial liquid absorption part 2a has been described as an example. The partial liquid absorption part 2b may absorb water and the second partial liquid absorption part 2a may absorb alcohol. In the case where the liquid absorbent core 1 is heated from the side surface 7 side, in FIGS. A temperature distribution is preferred.

  The average porosity of the first and second partial liquid-absorbing parts 2a and 2b can be determined in accordance with, for example, a measurement method (JIS R1634) of sintered ceramic density / open porosity of fine ceramics.

  The thermal conductivity of the first and second partial liquid-absorbing parts 2a, 2b can be determined in accordance with the thermal diffusivity / specific heat capacity / thermal conductivity test method (JIS R1611) of fine ceramics by the laser flash method. .

  The main components of the first and second partial liquid absorption parts 2a, 2b made of porous ceramics are, for example, the crystal phase of each partial liquid absorption part 2a, 2b is measured by X-ray diffraction, and the diffraction peak intensity is the highest. A large crystal phase can be determined as the main component. The result of quantitative analysis by ICP emission spectroscopy can also be taken into account for determining the main component.

  Next, the manufacturing method of the liquid absorption core 1 of this invention is illustrated.

  The first and second partial liquid-absorbing parts 2a and 2b constituting the liquid-absorbing core 1 are made of, for example, porous ceramics mainly composed of any one of alumina, mullite, silica, zirconia, silicon nitride, and silicon carbide. Become.

  With respect to the manufacturing method of the liquid absorbent core 1 when the first and second partial liquid absorbent parts 2a and 2b are mainly composed of alumina, the liquid absorbent core 1 having the shape shown in FIGS. 2 (a) and 2 (b) is taken as an example. I will explain.

An alumina powder made of alumina particles having a particle size of 50 to 200 μm and an alumina powder made of alumina particles having a particle size of 10 μm or less are prepared. An alumina binder in a range of 50 to 200 μm is mixed with an organic binder and granulated to produce granulated powder A ₁ having good fluidity. An alumina binder having a particle size of 10 μm or less is mixed with an organic binder and granulated to produce granulated powder A ₂ having good fluidity. The powder press molding method using a mold, for molding each granulated powder A ₁ square frame shape, the granulated powder A ₂ in a rectangular plate shape. Square-frame and square-plate shaped compacts are fired to produce square-frame and square-plate porous ceramics, respectively. Here, the firing temperature of the quadrangular frame-shaped or quadrangular plate-shaped compacts is set so that the average porosity of the two types of porous ceramics obtained is 20 to 60%. Therefore, the firing temperature is preferably 1300-1600 ° C.

  The outer peripheral surface of the obtained rectangular frame-shaped porous ceramic and the outer peripheral surface of the rectangular plate-shaped porous ceramic are polished, and the first and second partial liquid absorptions having the shapes shown in FIGS. 2 (a) and 2 (b) are obtained. The parts 2a and 2b are produced. The partition wall portion 3 is formed between the first and second partial liquid absorption portions 2a and 2b as follows.

  When the partition wall 3 is made of metal, the outer peripheral side of the second partial liquid absorption part 2b (the first partial liquid absorption part 2a side) is press-fitted inside the metal frame, and further, the metal frame is placed outside the metal frame. The first partial liquid absorption part 2a is press-fitted. When the partition wall 3 is glass, glass paste is applied to the entire outer peripheral side (the first partial liquid absorbing part 2a side) of the second partial liquid absorbing part 2b and the entire inner peripheral side of the first partial liquid absorbing part 2a. After applying and fitting the first and second partial liquid-absorbing parts 2a and 2b without gaps, the glass paste is melted and solidified by heat treatment. When the partition wall portion 3 is made of resin, adhesive is applied to the entire outer peripheral side (the first partial liquid absorbing portion 2a side) of the second partial liquid absorbing portion 2b and the entire inner peripheral side of the first partial liquid absorbing portion 2a. After the resin is applied and the first and second partial liquid absorbing portions 2a and 2b are fitted without a gap, the resin is solidified to produce a liquid absorbing core.

  When the main component of the first and second partial liquid absorption parts 2a and 2b is other than alumina, the partition part 3 can be formed in the same manner after the liquid absorption part 2 is produced as follows. For example, when the first and second partial liquid-absorbing parts 2a and 2b are silicon carbide, a coarse silicon carbide powder having an average particle diameter of 10 to 200 μm and a fine silicon carbide powder having an average particle diameter of 20 μm are prepared. A rectangular frame-shaped first partial liquid-absorbing part 2a is produced using a granular silicon carbide powder, and a square-plate-shaped second partial liquid-absorbing part 2b is produced using a fine silicon carbide powder. The firing temperature is preferably 1300 to 2000 ° C.

  When the main component of the first and second partial liquid-absorbing parts 2a and 2b is zirconia, coarse yttria solid-solution zirconia powder having an average particle diameter of 10 to 200 μm and fine yttria solid-solution zirconia powder having an average particle diameter of 20 μm And a square frame-shaped first partial liquid-absorbing part 2a using a coarse-grained powder, and a square-plate-shaped second partial liquid-absorbing part 2b using a fine-grained powder. The firing temperature is preferably 1200 to 1700 ° C.

  Similarly, when the main components of the first and second partial liquid absorption portions 2a and 2b are other than alumina, silicon carbide, and zirconia, the first and second partial liquid absorption portions are similarly formed using coarse particles and fine particles. The porosity of 2a, 2b can be varied. Further, a porous ceramic may be produced by appropriately adding a sintering aid.

  The main components of the first and second partial liquid-absorbing parts 2a and 2b may be different from each other.

  The average porosity of the porous ceramics constituting the first and second partial liquid absorbing parts 2a and 2b can be changed by changing the firing temperature.

  In addition, according to the present invention, not only in such a fuel cell, but also for a plurality of types of liquids having different surface tensions, the liquid absorption amount can be individually controlled by controlling the liquid absorption amount to a predetermined range. It can also be applied to drug vaporizers such as fragrances and insecticides. Here, the liquid can be applied to various solutions such as an aqueous solution, an organic solvent, a liquid fuel, an electrolytic solution, and a liquefied gas, and includes, for example, absorbing and reacting two liquid reactive liquids.

  The following liquid absorbent core was prepared.

(Liquid absorption core size)
Liquid absorption core in FIG. 1: first partial liquid absorption part 2a made of porous ceramics (outer diameter 20 mm, internal diameter 10 mm, length 30 mm), second partial liquid absorption part 2b made of porous ceramics (outer diameter 10 mm) , Length 30 mm).

  Liquid absorption core in FIG. 2: first partial liquid absorption part 2a made of porous ceramics (outer side 15 × 15 mm, inner side 7 × 7 mm, square frame having a thickness of 2 mm), second made of porous ceramics Partial liquid absorption part 2b (outer side 5 × 5 mm square plate-like body).

  Liquid absorption core in FIG. 3: The size of the first and second partial liquid absorption parts 2a and 2b made of porous ceramics having an outer side of 20 × 20 mm and divided into four is 9 mm × 9 mm × thickness. 5 mm.

(Partition wall)
The partition wall 3 was formed on the liquid absorbent core 2 as described above. In addition, when the partition part 3 was a metal, the metal of the material was press-fitted, and the dimensional relationship with the metal of the porous ceramics 2a and 2b was H7 tolerance (JIS B0401), respectively. When the partition part 3 was glass, it heat-processed at 800 degreeC using the composition borosilicate glass paste. When the partition wall 3 is a resin, an epoxy resin is used.

(1st, 2nd partial liquid absorption part 2a, 2b)
A porous ceramic mainly composed of alumina, silicon carbide (SiC), or zirconia was produced by the method described above.

  The average porosity and thermal conductivity of the porous ceramic were measured by cutting the porous ceramic from the sample using the method described above.

  The side surface 7 and the inside of the metal cylinder were sealed with a heat-resistant resin.

  Next, methanol is immersed in one surface 5a (lower side) of the second partial liquid absorbing part 2b of the obtained liquid absorbing core 2, and pure water is immersed in one surface 6a (lower side) of the first partial liquid absorbing part 2a. Then, methanol and pure water are absorbed on the other side 5b (upper side) and the other side 6b (upper side), and methanol and water are continuously vaporized so that the other side 5b and 6b side is about 110 ° C. An experiment for reforming for 6 hours was conducted. At that time, the upper part on the side surface 7 side was heated. The gas components generated by the reforming were analyzed by gas chromatography.

  After the modification experiment, the average porosity of the second partial liquid absorption part 2b was measured. The amount of carbon residue in the second partial liquid absorption part 2b was measured using an Auger electron spectroscopic analyzer.

  Further, the total amount of water and methanol absorbed from the first and second partial liquid absorbing portions 2a and 2b was measured and converted into a (methanol / water) molar ratio, which was defined as the liquid absorbing molar ratio.

  As a result, the gas component reformed using the sample of the present invention was mostly composed of hydrogen gas and carbon dioxide, and contained about 0.2 to 0.3% carbon monoxide. As a result, it was found that the liquid absorption core 2 can be sufficiently modified after liquid absorption and vaporization.

The results are shown in Table 1.

  As can be seen from Table 1, the sample no. 1-15, the average porosity before and after modification was as small as 10% or less. Particularly, the sample No. 2 in which the partial liquid absorption part 2b is mainly composed of silicon carbide (SiC). 1 to 11, 14 and 15, the change in average porosity before and after the modification was as small as 5% or less. Sample No. 2 in which the partial liquid absorption part 2b is made of alumina or zirconia. In Nos. 12 and 13, the change in average porosity before and after the modification was within 7% and 10%, respectively, which was larger than that of the sample in which the partial liquid absorption part 2b was made of silicon carbide.

  In the sample of the present invention, the carbon residue after the modification is as small as 0.07% by mass or less, and among these, the partial liquid absorption part 2b is Sample No. whose main component is silicon carbide. The amount of carbon residues 1 to 11, 14 and 15 was particularly small, 0.02% by mass or less. Sample No. 2 in which the liquid absorption part 2 is made of alumina or zirconia. Nos. 12 and 13 had carbon residues of 0.06% by mass and 0.07% by mass, respectively, and were more than the sample in which the partial liquid absorption part 2b was made of silicon carbide.

  The liquid absorption molar ratio is the sample No. 1, 3, 4, 7, 8, 10, 11, 14, 15 are 1, sample No. 2, 9, 12, 13 is 1.1, sample No. 5 and 6 were 0.9. The reason why the carbon residue of the sample having a liquid absorption molar ratio of 1.1 was 0.02 to 0.07% by mass was that the carbon remaining as the residue increased because the methanol was reformed in an excessive state. It is done. Sample No. with a liquid absorption molar ratio of 0.9 was used. The reason why the carbon residue of 5 and 6 was 0.01% by mass was that water was excessive at the time of reforming. Therefore, the reforming of the other surface 5b side of the partial liquid absorption part 2b was caused by the heat of vaporization of water. It is presumed that due to the local drop in the quality temperature, water becomes less likely to vaporize and supply becomes insufficient.

  Sample No. shown in Table 1 In the state which heated the liquid absorption core 2 of 1,14,15 to 160 degreeC, it poured into the pure water of 25 degreeC, and the rapid cooling test was done. As a result, the sample No. 3 in which the partition wall 3 is made of metal. No cracks that caused problems in the liquid absorption part were observed in Sample No. 1 in which the partition wall part 3 was made of glass. 14, Sample No. made of epoxy resin. No. 15 had a fine crack in the partition 3.

  However, as a result of performing the same rapid cooling test by changing the heating temperature from 160 ° C. to 110 ° C., sample No. No problem cracks were found in any of 1, 14, and 15.

  Next, as a comparative example, a sample outside the scope of the present invention was prepared in the same manner as in the example except for the following and evaluated in the same manner as in the example.

  Sample No. 16 is Sample No. 1 is a sample in which a porous ceramic made of alumina without partition walls 3 is formed as a whole. Sample No. 17 is a sample no. 1 is a sample using porous alumina having an average porosity of 20% in place of the partition wall 3. Sample No. 18 is a sample made of porous alumina having an outer diameter of 20 mm and a length of 30 mm. Sample No. Reference numeral 19 denotes a liquid absorbent core 11 having the structure shown in FIG. 5, and the liquid absorbent core 11 having an average porosity of 40% for the liquid absorbent part 2 made of porous ceramics (a combination of the partial liquid absorbent parts 12 a and 12 b). . 5A is a perspective view, and FIG. 5B is a cross-sectional view taken along line E-E ′ of FIG. The liquid absorption parts 12 a and 12 b are partitioned by a partition wall part 13.

The results of the comparative example are shown in Table 2.

  In Table 2, the inner side means the inner side of the liquid absorption core, and the outer side means the liquid absorption part outside the liquid absorption core. As is clear from Table 2, the average porosity of all the samples was greatly reduced after the modification. Also, the carbon content was as large as 0.5 to 1% by mass. The liquid absorption molar ratio was also as large as 1.3 to 3.

It is a figure which shows one Embodiment of the liquid absorption core which concerns on this invention, (a) is a perspective view, (b) shows sectional drawing, respectively. It is a figure which shows one Embodiment of the liquid absorption core which concerns on this invention, (a) is a perspective view, (b) shows sectional drawing, respectively. It is a figure which shows one Embodiment of the liquid absorption core which concerns on this invention, (a) is a perspective view, (b) shows sectional drawing, respectively. It is a figure which shows one Embodiment of the liquid absorption core which concerns on this invention, (a) is a perspective view, (b) shows sectional drawing, respectively. (A) is a perspective view of the liquid absorption core as a comparative example, (b) is sectional drawing of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11: Liquid absorption core 2: Liquid absorption part 2a, 2b, 12a, 12b: Partial liquid absorption part 3, 13: Partition part 5a, 6a: One side 5b, 6b: The other side 7: Side

Claims (6)

A liquid-absorbing portion having a first surface and the other surface facing the first surface, and made of porous ceramics;
A partition portion made of a dense material that partitions the liquid absorption portion from one surface to the other surface;
Ri Do different average porosity of at least one other portion liquid-absorbing portion of the partial liquid absorbing portions partitioned by the partition wall portion,
In a set of the partial liquid absorption parts having different average porosity, one partial liquid absorption part absorbs alcohol, and the other partial liquid absorption part absorbs water. A liquid absorbent core for a fuel cell . 2. The liquid absorbent core for a fuel cell according to claim 1, wherein an average porosity of the partial liquid absorbent is 20 to 60%. The liquid absorbent core for a fuel cell according to claim 1 or 2, wherein a cross-sectional shape parallel to one surface or the other surface of the partition wall is radial or concentric. The liquid absorption core for a fuel cell according to any one of claims 1 to 3, wherein a thermal conductivity of the liquid absorption part is 3 W / (m · K) or more. The liquid absorbent core for a fuel cell according to any one of claims 1 to 4, wherein the porous ceramic contains silicon carbide as a main component. The liquid-absorbent core for a fuel cell according to any one of claims 1 to 5, wherein the partition wall contains a metal as a main component.

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