JP5732825B2 - Cylindrical MEA manufacturing method, gas decomposing element including this cylindrical MEA and power generator - Google Patents

Description

  The present invention relates to a method for manufacturing a tubular MEA. More specifically, the present invention relates to a method of manufacturing a cylindrical MEA that can be used for a gas decomposition element and can efficiently decompose a predetermined gas, a gas decomposition element including the same, and a power generation apparatus.

  For example, ammonia is an indispensable compound for agriculture and industry, but is harmful to humans, so various methods for decomposing ammonia in water and air are known. In order to decompose and remove ammonia from water containing a high concentration of ammonia, a method has been proposed in which ammonia water is sprayed and contacted with an air stream to separate ammonia in the air and contacted with hypobromous acid solution or sulfuric acid. (Patent Document 1). In addition, a method of separating ammonia in the air by the same process as the above method and burning it with a catalyst (Patent Document 2) and a method of decomposing ammonia-containing wastewater into nitrogen and water using a catalyst have been proposed. (Patent Document 3). Furthermore, the waste gas of the semiconductor manufacturing apparatus often contains ammonia, hydrogen, etc., and in order to completely remove the odor of ammonia, it is necessary to remove it to the ppm order. For this purpose, many methods have been used in which harmful gas is absorbed in water containing chemicals through a scrubber when the waste gas of the semiconductor device is released. On the other hand, in order to decompose harmful gases at a low running cost without input of energy, chemicals, etc., a waste gas treatment method in a semiconductor manufacturing apparatus or the like that decomposes ammonia with a phosphoric acid fuel cell has been proposed (patent) Reference 4).

JP-A-7-31966 Japanese Patent Laid-Open No. 7-116650 Japanese Patent Laid-Open No. 11-347535 JP 2003-45472 A Japanese Patent No. 3238086

  A method using a chemical such as a neutralizing agent as described in Patent Document 1, a method of burning as described in Patent Document 2, and a thermal decomposition using a catalyst as described in Patent Document 3 Ammonia can be decomposed by a reaction method. However, these methods require chemicals and external energy (fuel), and further require periodic replacement of the catalyst, resulting in increased running costs.

  In addition, since the apparatus becomes large, it is difficult to secure a space when it is additionally provided in existing facilities. In addition, for the device that uses phosphoric acid fuel cells to remove ammonia in the exhaust gas from the production of compound semiconductors, the electrolyte is liquid, so the partition between the air side and the ammonia side cannot be made compact, and the size of the device is reduced. There was a problem that was difficult.

  In order to solve the above problem, as described in Patent Document 5, a cylindrical solid electrolyte layer, and a first electrode layer and a second electrode layer formed so as to sandwich the solid electrolyte layer from inside and outside A cylindrical MEA (Membrane Electrode Assembly) configured with the above can be employed.

  Conventionally, the cylindrical MEA is formed by firing a solid electrolyte layer by compacting or the like, and thereafter, a fuel electrode is laminated and fired on the solid electrolyte layer, and the air electrode is formed by various methods. It was necessary to form it separately. For this reason, there existed a problem that a manufacturing cost increased while manufacturing man-hours increased.

  In the present invention, by utilizing an electrochemical reaction using a solid electrolyte, it is possible to obtain a large processing capacity while suppressing running cost, and to reduce the manufacturing process and manufacturing cost of the cylindrical MEA. It is an object of the present invention to provide a method for producing a MEA.

The present invention relates to a cylindrical MEA (Membrane Electrode Assembly) comprising a cylindrical solid electrolyte layer, and a first electrode layer and a second electrode layer formed so as to sandwich the solid electrolyte layer from inside and outside. ) Is a method of manufacturing a cylindrical MEA , which is molded using a rubber press molding method, wherein the first unfired cylindrical portion constituting one of the solid electrolyte layer or the electrode layer is formed in an internal space. A first pressing step in which a cylindrical pressure rubber mold provided with a central mold portion to be filled is filled with a predetermined powder material and pressed, and the pressure is released by releasing the pressure. The inner periphery of the rubber mold and the first unfired cylindrical part is enlarged to form a tubular mold part between the outer periphery of the central mold part and the first unfired cylindrical part. Mold space forming step and a predetermined powder on the cylindrical mold portion Charge by re-pressurizing with filling, a second forming step of forming a second unfired tubular portion which constitutes the other one of the solid electrolyte layer or the electrode layer, non the first And a firing step of firing a tubular body including the fired tubular portion and the second unfired tubular portion to form a tubular fired body.

  In the manufacturing method of the cylindrical MEA according to the present invention, the first green cylindrical portion and the second green cylindrical portion are formed by the first molding step and the second molding step. An integrally formed unfired cylindrical body is formed. And after that, this unfired cylindrical body is fired as a unit.

  That is, in the present invention, the solid electrolyte layer and at least one of the electrode layers are integrally molded and fired integrally. For this reason, the number of manufacturing steps can be reduced and the manufacturing cost can be reduced as compared with the case where these portions are separately formed.

  Moreover, the solid electrolyte layer and one electrode layer laminated | stacked mutually can be integrally molded in the unbaked state, and can be baked integrally after that. For this reason, the solid electrolyte layer and the one electrode layer are formed in close contact with each other, and good conductivity between the solid electrolyte layer and the one electrode layer is ensured in the entire bonding surface. . Therefore, a cylindrical MEA having a high gas decomposition ability can be formed.

And a third forming step of forming a third unfired cylindrical portion constituting the solid electrolyte layer and the remaining one of the electrode layers by using a predetermined powder material, The first unfired cylindrical part, the second unfired cylindrical part, and the third unfired cylindrical part can be fired at once. Accordingly, the solid electrolyte layer and the two electrode layers formed so as to sandwich the solid electrolyte layer can be fired in a single firing step, and the number of steps can be further reduced.

In the above SL first molding step and the second molding step, a first unsintered tubular portion constituting the solid electrolyte layer, the one that is formed on the inside of the green cylindrical portion of the first Forming an electrode layer and performing an electrode layer forming step of forming the other electrode layer on the outer periphery of the solid electrolyte layer after the firing step of firing the cylindrical body having these unfired tubular portions. Can do.

That is, after forming and baking a solid electrolyte layer and one electrode layer, the other electrode layer is separately formed. The method for forming the other electrode layer is not particularly limited. For example, the other electrode layer forming material can be laminated and formed into a cylindrical body obtained by baking the other two layers, and then fired again. Further, the other electrode can be formed by a method other than firing. For example, it can be formed using a technique such as thermal spraying.

On the surface of the upper Symbol first electrode layer and / or the second electrode layer, a conductive layer formation step of forming a porous conductive layer may be Maseru free.

  When the current collector of the first electrode and the second electrode is composed of a plurality of members, if the contact resistance between the members is large, the electrochemical reaction in the electrodes is hindered, and the efficiency of gas decomposition decreases. For example, when adopting a configuration in which a porous metal body is inserted into the inner surface side of the cylindrical MEA as the current collector of the first electrode (anode) and directly contacted with the first electrode, these porous bodies are used. There is a problem that it is difficult to increase the contact area and the contact pressure between the porous metal body and the first electrode, and the resistance between these members increases.

  As a technique for avoiding the inconvenience, the contact resistance between the electrode and the current collector can be reduced by holding the metal mesh sheet in contact with the electrode. For example, one metal mesh sheet can be disposed so as to be in contact with the entire inner peripheral surface of the first electrode layer formed inside. Further, by inserting the porous metal body inside the metal mesh sheet, the dendritic metals in the porous metal body are pressed together, and the metal mesh sheet and the porous metal body enter each other's gap. They can be brought into contact with each other and the contact resistance can be reduced.

  On the other hand, it is difficult to make the metal mesh sheet uniformly contact the entire inner surface of the first electrode layer. That is, the contact pressure between the surface of the first electrode layer and the metal mesh sheet is often different, or a part of the contact pressure rises from the surface of the first electrode. In such a case, uniform current collection cannot be performed on the surface of the first electrode, and a uniform electrochemical reaction cannot be generated in the entire region of the first electrode. For this reason, the efficiency of an electrochemical reaction falls. By forming the conductive layer on the surface of the first electrode layer, conductivity between the electrode layer and the current collector can be ensured in the entire region. Further, since the conductive layer is porous, it does not hinder gas contact with each electrode layer.

  As the porous conductive layer, a porous conductive paste coating layer can be provided. For example, by providing a porous conductive paste coating layer on the inner peripheral surface of the first electrode, the first electrode and the porous metal body are connected to the porous conductive paste coating layer and the metal. Conducted through the mesh sheet.

  By providing the conductive paste coating layer, a part of the surface of the metal mesh sheet is embedded in the conductive paste coating layer, so that the metal mesh sheet and the first electrode can be reliably connected. it can. For this reason, the contact resistance between these can be reduced significantly. In addition, the entire surface of the metal mesh sheet can be uniformly contacted with the first electrode. For this reason, the electrical resistance between the first electrode and the metallic mesh sheet does not partially increase. Further, by applying the conductive paste coating layer to the entire surface of the first electrode, even when the metal mesh sheet is separated from the conductive paste coating layer, current collection on the surface of the first electrode is ensured. It becomes possible. For this reason, even if a part of the metal mesh sheet is separated from the conductive paste coating layer by the action of temperature or the like, the current collection effect is not lowered. Moreover, since the conductive paste coating layer is porous, it does not prevent the gas from coming into contact with the first electrode. Therefore, it is possible to generate an electrochemical reaction uniformly in the entire region of the first electrode layer to greatly improve the efficiency of the gas decomposition reaction, and to increase the gas decomposition processing capacity.

  The form of the metal mesh sheet is not particularly limited. For example, the metal mesh sheet can be formed in a cylindrical shape and disposed over the entire surface so as to cover the first electrode.

  Further, the external configuration of the metal mesh sheet is not particularly limited. For example, a woven fabric, a non-woven fabric, a punched sheet, or the like can be used. In order to ensure flexibility, pore diameter uniformity, etc., it is preferable to employ a woven fabric.

  The metal material constituting the metal mesh sheet is not particularly limited. For example, it is preferable to employ a metal mesh sheet formed of a material such as Ni, Ni—Fe, Ni—Co, Ni—Cr, or Ni—W. Also, a metal mesh sheet having a silver plating layer or the like formed on the surface layer can be employed. When a catalytic reaction is expected, it is preferable to employ a metal mesh sheet formed from a material such as Ni-W.

  The porous conductive paste coating layer can be formed from a paste containing various conductive particles. For example, the porous conductive paste coating layer can be formed from a paste containing silver particles. Silver particles have high conductivity, and can reduce the electrical resistance of the first electrode as a current collector, thereby improving the gas decomposition treatment capacity. Also, it is stable and hardly oxidizes.

  Conductive pastes other than the silver paste can also be employed. For example, a conductive paste containing gold particles, a conductive paste containing platinum particles, or the like can be used.

  In order to increase the efficiency of the gas decomposition reaction, the porosity of the conductive paste coating layer is preferably set to 20 to 80%. When the porosity is 20% or less, it becomes difficult to guide the gas into the conductive paste coating layer, and the efficiency cannot be increased. On the other hand, when the porosity is 80% or more, it is difficult to ensure sufficient conductivity and the strength of the coating layer cannot be ensured. Furthermore, it is more preferable to set the porosity to 40 to 60%.

  The thickness of the conductive paste coating layer can be set to 5 to 300 μm. When the thickness is 5 μm or less, the metal mesh sheet cannot be uniformly contacted with the conductive paste coating layer, and it is difficult to ensure sufficient conductivity. On the other hand, when the thickness is 300 μm or more, it is difficult to form a conductive paste coating layer having a sufficient porosity. In order to ensure conductivity and porosity, it is more preferable to provide a conductive paste coating layer having a thickness of 5 to 100 μm.

  A method for forming the conductive paste coating layer in a porous manner is not particularly limited. In order to ensure the required porosity, a conductive paste can be formed by blending a predetermined amount of a binder that disappears at a predetermined temperature. In order to prevent shrinkage of the conductive paste coating layer when the binder disappears, it is preferable to add a sublimation binder. For example, it is preferable to employ a conductive paste containing a naphthalene binder. The conductive paste coating layer is heated to a predetermined temperature to remove the binder, and is made porous. Further, the conductive particles are baked at a higher temperature, whereby a porous conductive paste coating layer is formed. Is formed.

  The form in which the conductive paste coating layer is provided is not particularly limited. For example, the porous conductive paste coating layer can be formed on the entire surface of the first electrode layer formed inside. By forming the conductive paste coating layer on the entire surface of the first electrode layer, even when a part of the metal mesh sheet is separated from the conductive paste coating layer, the current collecting performance is not lowered.

  In addition, the porous conductive paste coating layer can be provided in a predetermined pattern. For example, the porous conductive paste coating layer can be formed so as to contact the metal mesh sheet in a strip shape or a lattice shape. By forming with the said pattern, when employ | adopting the electrically conductive paste containing an expensive metal particle, cost can be reduced.

  The said conductive layer formation process can be performed in any step of the manufacturing process of cylindrical MEA. For example, after the conductive paste is laminated and applied to the unfired cylindrical body, the paste is maintained at a temperature at which it becomes porous, and then the unfired tubular body is integrally fired by increasing the temperature. it can. Further, after the cylindrical body described in claim 1 or 2 is fired, a conductive paste can be applied to make it porous separately.

The present invention according to the manufacturing method of the cylindrical MEA forming is carried out using the LA bar press molding the green compact. That is, the first molding for molding the first unfired cylindrical part by filling and pressing a cylindrical pressure rubber mold provided with a central mold part filling the internal space with a predetermined powder material. a step, by releasing the pressure, and diameter of the inner peripheral portion of the pressure rubber type and the first unsintered tubular portion, between the outer peripheral portion of the central mold portion, the A mold space forming step for forming a cylindrical mold part corresponding to the second unfired cylindrical part, and filling the cylindrical mold part with a predetermined powder material and repressurizing the second mold part The manufacturing method of the said cylindrical MEA can be comprised including the said 2nd shaping | molding process which shape | molds an unbaking cylindrical part.

The rubber press molding method is a method of filling a rubber mold with powder or preformed green compact and applying a high hydrostatic pressure from the outer periphery to form a homogeneous compression molded body. The rubber mold is compressed and deformed in the compression process, and returns to its original form by elasticity when the compression force is released. That is, the cylindrical body EMA is formed by utilizing the compression-decompression deformation of the rubber mold.

In the manufacturing method, first, a first molding step is performed in which the first unfired cylindrical portion is formed by a normal method of rubber press molding. Thereafter, when the hydrostatic pressure is released, the central mold is expanded by expanding the inner peripheral portion so that the unfired cylindrical portion compressed around the central mold portion is attached to the inner surface of the rubber mold. A mold space forming step for forming a cylindrical mold part corresponding to the second unfired cylindrical part is performed between the outer peripheral part of the part and the inner peripheral part of the first unfired cylindrical part. And the powder material which forms the 2nd non-baking cylindrical part is filled in the said cylindrical type | mold part, and a hydrostatic pressure is applied again, The said 1st non-baking cylindrical part and said 2nd The unfired cylindrical part is integrally formed. Then, a cylindrical body provided with a solid electrolyte layer and one electrode layer by integrally firing a cylindrical body provided with the first unsintered cylindrical part and the second unsintered cylindrical part. Can be formed.

  By adopting the above manufacturing method, the solid electrolyte layer and the one electrode layer can be formed continuously and can be fired in a single firing step. For this reason, while being able to reduce a manufacturing process, manufacturing cost can be reduced.

In the method of manufacturing the cylindrical MEA forming is carried out by using a rubber pressing method, a cylindrical pressing rubber mold having a centric portion to fill the interior space is pressurized by filling a predetermined powder material by a first forming step of forming a first unfired tubular portion, by releasing the pressure, and diameter of the pressure rubber mold, and the pressure rubber mold inner peripheral portion A mold space forming step of forming a cylindrical mold portion corresponding to the second unfired cylindrical portion between the outer periphery of the first unfired cylindrical portion, and a predetermined amount in the cylindrical mold portion. to fill the powder material by re-pressurizing, and the second forming step of forming the second unsintered tubular portion can Maseru free.

The above invention is configured to form a cylindrical forming space for forming the second unfired cylindrical portion on the outer peripheral side of the first unfired cylindrical portion molded in the first molding step. Is. By adopting this method , the manufacturing process can be reduced and the manufacturing cost can be reduced similarly to the above-described invention .

Further, a cylindrical MEA (Membrane Electrode Assembly) comprising a cylindrical solid electrolyte layer, and a first electrode layer and a second electrode layer laminated so as to sandwich the solid electrolyte layer from inside and outside. in the manufacturing method, the outer periphery of the rod-shaped sacrificial portion which can be eliminated by performing a predetermined process, a first forming step of forming the first green cylindrical portion, said first unfired the outer periphery of the cylindrical portion, said second forming step of forming a second unfired cylindrical portion, and a sacrificial portion elimination step of eliminating the rodlike sacrificial portion, the first unsintered tubular parts and firing the tubular body and a said second unsintered tubular portion firing step of forming a tubular fired body may be employed including manufacturing methods.

In the manufacturing method , the first unfired cylindrical portion and the second unfired cylindrical portion can be formed on the outer periphery of the rod-shaped sacrificial mold portion by a continuous forming process. The molding method is not particularly limited. The above steps can be performed by sequentially applying the materials constituting the first unfired cylindrical part and the second unfired cylindrical part to the outer peripheral part of the sacrificial mold part in a predetermined thickness. it can. Further, the first unfired cylindrical portion and the second unfired tubular portion can be laminated by using a two-color injection molding method or the like.

  The sacrificial mold part is configured to be able to disappear by performing a predetermined process. For example, a sacrificial mold portion is formed using a resin material similar to the binder blended in the material constituting the cylindrical portion, and the firing is performed by holding the binder at a temperature at which the binder sublimates for a predetermined time before the firing step. It can be eliminated before the process.

  By employing the sacrificial mold part, the first unfired cylindrical part and the second unfired cylindrical part can be molded with high accuracy. In addition, two unfired cylindrical portions can be formed in a continuous process, and these unfired tubular portions can be integrally fired in a single firing step. Therefore, the manufacturing process can be reduced and the manufacturing cost can be reduced.

The forming method using the sacrificial mold part can form three layers of a solid electrolyte layer and two electrode layers arranged so as to sandwich the solid electrolyte layer at a time. That is, the outer peripheral portion of the rod-shaped sacrificial portion which can be eliminated by performing a predetermined process, a first forming step of forming the first green tubular portions constituting one of said electrode layer , the outer peripheral portion of the first unsintered tubular portion, and a second forming step of forming a second unfired tubular portion constituting the solid electrolyte layer, the second unsintered tubular portion A third forming step of forming a third unfired cylindrical portion constituting the remaining one of the electrode layers on the outer peripheral portion; a sacrificial die portion disappearing step of eliminating the rod-like sacrificial die portion; including producing a firing step of firing the tubular body to form a cylindrical sintered body and a green cylindrical portion 1 and the second unsintered tubular portion and the third green cylindrical portion The method can also be adopted.

In the above manufacturing method, the surface of the first electrode layer and / or the second electrode layer to form a porous conductive layer, the conductive layer forming step can Maseru free.

  The conductive layer forming step can be performed separately from the solid electrolyte layer and electrode layer forming step. In addition, a conductive layer forming material may be provided on the unfired cylindrical body constituting the solid electrolyte layer and the electrode layer, and the conductive layer may be made porous in the sacrificial mold part disappearance step.

  The material which comprises the said 1st electrode layer and said 2nd electrode layer is not specifically limited. For example, the first electrode and / or the second electrode can be a fired body containing a metal particle chain mainly composed of nickel (Ni) and an ion conductive ceramic. The metal particle chain refers to a bead-like elongated metal body formed by a series of metal particles. Ni, Fe-containing Ni, or Ni, Fe-containing Ni may be a metal containing a small amount of Ti. When the surface of Ni or the like is oxidized, the surface of the metal particle chain is oxidized, and the contents (portion inside the surface layer) are not oxidized and retain the conductivity of the metal.

For this reason, for example, when the ion moving in the solid electrolyte layer is an anion (in some cases, it is a cation), the following effects are produced.
(A1) When the metal particle chain is contained in the first electrode layer (anode), the anion moving from the solid electrolyte layer and the gas molecule in the gas guided from the outside of the anode to the anode in the anode Is promoted by the oxide layer of the metal particle chain (catalysis), and an anion is added to promote the chemical reaction at the anode (acceleration by charge). And as a result of the chemical reaction, the conductivity of the generated electrons can be ensured by the metal portion of the metal particle chain. As a result, the electrochemical reaction involving charge transfer at the anode can be accelerated as a whole. When the metal particle chain is contained in the first electrode (anode), a positive ion, for example, a proton is generated at the anode to move the positive ion through the solid electrolyte layer to the cathode. Can be obtained as well.
However, the oxide layer of the metal particle chain is surely formed by a firing treatment before use, but the oxide layer is often lost due to a reduction reaction during use. Even if the oxide layer disappears, the above-described catalytic action may or may not be reduced. In particular, Ni containing Fe or Ti has high catalytic action even without an oxide layer.
(A2) When the metal electrode chain (cathode) is contained in the second electrode layer (cathode), the chemical reaction of gas molecules in the gas guided from the outside of the cathode to the cathode is converted into the oxide layer of the metal particle chain. (Catalytic action) and the conductivity of electrons from the external circuit is improved, and the chemical reaction at the cathode is promoted by the participation of the electrons (promoting action by charge). Then, anions can be efficiently generated from the molecules and delivered to the solid electrolyte layer. As in (A1), in the case of (A2), the electrochemical reaction between the cation that has moved through the solid electrolyte layer, the electrons that have flowed through the external circuit, and the second gas can be promoted. For this reason, the electrochemical reaction accompanied with transfer of the electric charge in a cathode can be accelerated as a whole like the case where it is included in the anode. In what case, the metal particle chain is included in the cathode, depending on the gas to be decomposed.
(A3) When the metal particle chain is contained in the anode and the cathode, the effects (A1) and (A2) can be obtained.

  In many cases, the electrochemical reaction is limited by the moving speed or moving time of the solid electrolyte layer of ions. In order to increase the moving speed of ions, the gas decomposition element is usually provided with a heating device such as a heater, and is usually set at a high temperature, for example, 600 ° C to 1000 ° C. By raising the temperature, not only the ion transfer speed but also chemical reactions involving charge transfer at the electrodes are promoted.

  When the ions moving through the solid electrolyte layer are anions, they are generated and supplied by a chemical reaction at the cathode as described above. Molecules in the fluid introduced at the cathode react with electrons to generate anions. The produced anion moves in the solid electrolyte layer to the anode. Electrons participating in the reaction at the cathode come from an external circuit (including a capacitor, a power source, and a power consuming device) that connects the anode and the cathode. When the ions moving through the solid electrolyte layer are cations, they are generated by an electrochemical reaction at the anode and move through the solid electrolyte layer to the cathode. Electrons are generated at the anode and flow through an external circuit to the cathode and participate in the electrochemical reaction at the cathode. The electrochemical reaction may be a power generation reaction as a fuel cell, or may be an electrolysis reaction.

In addition, the solid electrolyte can be configured to have oxygen ion conductivity or proton conductivity. When an oxygen ion conductive solid electrolyte is used, for example, electrons and oxygen molecules are reacted at the cathode to generate oxygen ions, which are moved through the solid electrolyte layer to cause a predetermined electrochemical reaction at the anode. be able to. In this case, since the moving speed of oxygen ions in the solid electrolyte layer is not large compared to protons, the temperature is sufficiently increased and / or the thickness of the solid electrolyte layer is sufficiently thin to obtain a practical level of decomposition capacity. Such measures are necessary.
On the other hand, barium zirconate (BaZrO ₃ ) is known as a proton conductive solid electrolyte. When a proton-conducting solid electrolyte is used, for example, ammonia is decomposed at the anode to generate protons, nitrogen molecules and electrons, and the protons are transferred to the cathode through the solid electrolyte layer. (H ₂ O) is produced. Since protons are small compared to oxygen ions, the moving speed in the solid electrolyte layer is high, so that a practical decomposition level can be obtained by lowering the heating temperature.

  Further, for example, when ammonia decomposition is performed using a cylindrical MEA, when the inner side is an anode, the oxygen ion conductive solid electrolyte is a reaction that generates water on the inner side (anode) of the cylindrical body. Water forms water droplets near the outlet where the temperature is low, causing pressure loss. In contrast, when a proton conductive solid electrolyte is used, protons, oxygen molecules, and electrons are generated at the cathode (outside). Since the outside is almost open, even if it adheres as water droplets, pressure loss is unlikely to occur.

Further, the gas to be decomposed can be used as fuel, and a fuel cell can be constituted by the gas decomposition element to generate electric power.

  The gas to be decomposed is not particularly limited. For example, any one of the gas decomposition elements described above can be provided, and a gas containing ammonia can be introduced into the first electrode, and a gas containing oxygen molecules can be introduced into the second electrode. As a result, oxygen ions generated at the second electrode (cathode) are moved to the first electrode (anode), and ammonia and oxygen ions are catalyzed by the metal particle chain in the first electrode, and The reaction can be performed under the accelerating action of ions, and electrons generated as a result of the reaction can be quickly moved.

  The gas decomposing element according to the present invention is used not only for gas detoxification, but also in the field of a fuel cell and an original electrochemical reaction device utilizing gas decomposition, and is used for an electrode which is the basis of the device, for an electrochemical reaction. It is possible to contribute to the improvement of the efficiency, the downsizing of the apparatus, and the low running cost.

  According to the method for producing a gas decomposition element of the present invention, a cylindrical MEA constituting a gas decomposition apparatus having high gas decomposition efficiency and low running cost can be manufactured, and the number of manufacturing steps and manufacturing cost can be reduced.

(A) It is a longitudinal cross-sectional view which shows the gas decomposition element in Embodiment 1 of this invention, (b) is sectional drawing which follows the IB-IB line in (a). It is a figure which shows the electrical wiring system | strain of the gas decomposition element of FIG. It is a figure which shows the connection form of the external wiring with respect to cylindrical MEA, and a gas conveyance path. It is a flowchart of the manufacturing method of cylindrical MEA which concerns on 1st Embodiment of this invention. (A) (b) is a figure which shows each process in the manufacturing method of cylindrical MEA which concerns on the 1st Embodiment of this invention. (C) (d) is a figure which shows each process in the manufacturing method of cylindrical MEA which concerns on the 1st Embodiment of this invention. (E) (f) is a figure which shows each process in the manufacturing method of cylindrical MEA which concerns on the 1st Embodiment of this invention. (G) (h) is a figure which shows each process in the manufacturing method of cylindrical MEA which concerns on the 1st Embodiment of this invention. It is a flowchart of the manufacturing method of cylindrical MEA which concerns on 2nd Embodiment of this invention. (A) (b) (c) is a figure which shows each process in the manufacturing method of the cylindrical MEA which concerns on the 2nd Embodiment of this invention. (D) (e) (f) is a figure which shows each process in the manufacturing method of cylindrical MEA which concerns on the 2nd Embodiment of this invention. (A) (b) (c) (d) is a figure which shows each process in the manufacturing method of cylindrical MEA which concerns on the 3rd Embodiment of this invention. (E) (f) (g) is a figure which shows each process in the manufacturing method of cylindrical MEA which concerns on 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
(Embodiment 1)
FIG. 1A is a longitudinal sectional view of a gas decomposition element 10 according to Embodiment 1 of the present invention. Moreover, FIG.1 (b) is sectional drawing which follows the IB-IB line | wire in Fig.1 (a). In the present embodiment, the case where the present invention is applied to a gas decomposition element that decomposes ammonia gas will be described.

  The gas decomposition element 10 is provided with a first electrode layer (anode) 2 so as to cover the inner surface of the cylindrical solid electrolyte layer 1 and a second electrode layer (cathode) 5 so as to cover the outer surface. The cylindrical MEA 7 (1, 2, 5) is provided. The first electrode layer (anode) 2 may be called a fuel electrode, and the second electrode layer (cathode) 5 may be called an air electrode. The cylindrical MEA 7 (1, 2, 5) according to the present embodiment is formed in a right cylindrical shape as shown in FIG. The inner diameter of the cylindrical MEA is, for example, about 20 mm, but the dimensions and the like can be set according to the device to be applied. In the gas decomposition element 10 of the present embodiment, the anode current collector 11 is arranged so as to fill the inner cylinder of the cylindrical cylindrical MEA 7. Further, the cathode-side current collector 12 is arranged so as to wrap around the outer surface of the second electrode layer (cathode).

  The anode-side current collector 11 includes a silver paste coating layer 11g, a Ni mesh sheet 11a, a porous metal body 11s, and a central conductive rod 11k. The Ni mesh sheet 11a contacts the first electrode layer (anode) on the inner surface side of the cylindrical MEA 7 through the silver paste coating layer 11g, and conducts from the porous metal body 11s to the central conductive rod 11k. It is configured as follows. As the porous metal body 11s, in order to reduce the pressure loss of gas such as ammonia gas, it is preferable to use a metal plated body capable of increasing the porosity, for example, Celmet (registered trademark: Sumitomo Electric Industries, Ltd.). In order to reduce the electrical resistance between the first electrode layer (anode) and the anode-side current collector 11, the silver paste coating layer 11g and the Ni mesh sheet 11a are disposed.

  The cathode current collector 12 includes a silver paste coated wiring 12g and a Ni mesh sheet 12a. In the present embodiment, the Ni mesh sheet 12a is in contact with the outer surface of the cylindrical MEA 7 and is conducted to the external wiring. The silver paste-coated wiring 12g contains silver that acts as a catalyst for promoting the decomposition of oxygen gas in the second electrode layer (cathode) into oxygen ions, and lowers the electrical resistance of the cathode-side current collector 12. Contribute to. The silver paste coated wiring 12g having a predetermined property is a catalyst equivalent to the silver particles contained in the second electrode layer (cathode) because the silver particles contact the second electrode layer (cathode) while passing oxygen molecules. Exerts an effect. Moreover, it is less expensive than the inclusion in the second electrode layer (cathode).

  FIG. 2 is a diagram showing an electrical wiring system of the gas decomposition element 10 of FIG. 1 when the solid electrolyte layer 1 is oxygen ion conductive. The gas containing ammonia is introduced into the inner cylinder of the cylindrical MEA 7 with strict airtightness, that is, the space where the anode-side current collector 11 is disposed. When the cylindrical MEA 7 is used, the porous metal body 11s is used because gas passes through the inner surface side. From the viewpoint of reducing the pressure loss, as described above, a porous metal plated body, for example, the above-described Celmet can be used as the porous metal body 11s. The gas containing ammonia is in contact with the first electrode layer (anode) while passing through the voids of the porous metal body 11s, the Ni mesh sheet 11a, and the porous silver paste coating layer 11g, and the following ammonia decomposition reaction do.

Oxygen ions O ²⁻ are generated by an oxygen gas decomposition reaction at the second electrode layer (cathode), and reach the first electrode layer (anode) through the solid electrolyte layer 1. That is, it is an electrochemical reaction when oxygen ions, which are anions, move through the solid electrolyte layer 1.

In the first electrode layer (anode), the following reaction occurs.
(Anode reaction): 2NH ₃ + 3O ²⁻ → N ₂ + 3H ₂ O + 6e ⁻

More specifically, some ammonia causes a reaction of 2NH ₃ → N ₂ + 3H ₂ , and this 3H ₂
Reacts with the oxygen ion 3O ²⁻ to produce 3H ₂ O. Air, particularly oxygen gas, is introduced into the second electrode layer (cathode) so as to pass through the space S, and oxygen ions decomposed from oxygen molecules in the second electrode layer (cathode) are converted into the first electrode layer (anode). ) Toward the solid electrolyte layer 1.

In the first electrode layer (cathode), the following reaction occurs.
(Cathode reaction): O ₂ + 4e ⁻ → 2O ²⁻
As a result of the electrochemical reaction, electric power is generated, and a potential difference is generated between the first electrode layer (anode) and the second electrode layer (cathode), and the cathode-side current collector 12 and the anode-side current collector. The current I flows to 11. If a load, for example, a heater 41 for heating the gas decomposition element 10 is connected between the cathode-side current collector 12 and the anode-side current collector 11, electric power for that purpose can be supplied. The supply of the power to the heater 41 may be partial. In many cases, the supply amount of private power generation is often less than half of the power required for the entire heater.

  In the gas decomposition element 10 described above, in the first electrode layer (anode) on the inner surface side of the cylindrical MEA 7, the pressure loss of the gas passing therethrough is reduced while reducing the electrical resistance of the anode-side current collector 11. This is very important. In addition, on the second electrode layer (cathode) side, air does not pass through the cylinder, but the contact portion between the air and the second electrode layer (cathode) is increased in density, and the cathode-side current collector 12 has a low density. It is important to make resistance.

The above is an electrochemical reaction in which oxygen ions, which are anions, move through the solid electrolyte layer 1. For example, barium zirconate (BaZrO ₃ ) is used for the solid electrolyte layer 1 to transfer protons to the first electrode layer (anode). The reaction that is generated in step (1) and moves through the solid electrolyte layer 1 to the second electrode layer (cathode) is also a desirable embodiment of the present invention.

When proton conductive solid electrolyte layer 1 is used, for example, when ammonia is decomposed, ammonia is decomposed at the first electrode layer (anode) to generate protons, nitrogen molecules, and electrons. To move to the second electrode layer (cathode), and react with oxygen in the second electrode layer (cathode) to generate water (H ₂ O). Since protons are smaller than oxygen ions, the moving speed in the solid electrolyte layer is large. Therefore, a practical decomposition capacity can be obtained while lowering the heating temperature. The thickness of the solid electrolyte layer 1 can also be set to a thickness that can ensure strength.

  FIG. 3 is a diagram showing a connection form between the central conductive rod 11k and the external wiring 11e and a connection form between the cylindrical MEA 7 and the gas transport path 45. A tubular joint 30 made of a fluororesin is fitted to the end of the cylindrical MEA 7. In the fitting, the O-ring 33 housed on the inner surface side of the fastening portion 31b extending from the main body portion 31 of the tubular joint 30 to the solid electrolyte layer 1 is brought into contact with the outer surface of the ceramic solid electrolyte layer 1 as a fired body. So that the state is maintained. For this reason, the fastening portion 31b of the tubular joint 30 has an outer diameter tapered, and a screw is cut there, and the annular screw 32 is screwed into the screw. By fastening the annular screw in the direction in which the outer diameter increases, the fastening portion 31b is tightened from the outer surface, and the airtightness by the O-ring 33 can be adjusted.

The main body portion 31 of the tubular joint 30 is provided with a conductive through portion 37c that penetrates the main body portion 31 while maintaining airtightness, and is coated with a sealing resin 38 or the like in order to maintain airtightness. The conductive penetrating portion 37c is a cylindrical rod, and a screw for screwing the nut 39 is preferably cut in order to make a reliable conductive connection with the external wiring 11e. A conductive wire 37b is bonded to the distal end of the conductive through portion 37c in the tube, and a connection plate 37a is bonded to the other end of the conductive wire 37b.
Conductive connection between the connecting plate 37a and the tip 35 of the central conductive rod 11k is performed by screwing the screw 34 through the protruding hole 31a of the tubular joint 30 using a connecting tool such as a driver. By tightening the screw 34 by the driver, the electrical resistance (contact resistance) in the conductive connection between the tip 35 and the connection plate 37a can be almost eliminated.

  Further, the external wiring 12e can be circulated around the end of the Ni mesh sheet 12a of the cathode-side current collector 12, thereby leading to the outside. Since the second electrode layer (cathode) is located on the outer surface side of the cylindrical MEA 7, it is not as difficult as withdrawing from the anode current collector 11 to the outside.

  As the gas conveyance path 45, it is preferable to use a pipe such as an elastically deformable resin. By fitting the end portion of the pipe line to the outer periphery of the protruding hole portion 31 a and fastening with the fastener 47, an airtight connection can be obtained.

  The connection between the anode-side current collector 11 and the external wiring 11e and the connection between the tubular joint 30 and the gas transport path 45 in FIG. 3 are both realized with a very simple and small structure. Also, the above two types of connections are separated by the central conductive rod 11k and the tip portion 35 that is an accessory thereof to a position that is out of the main stream portion of the thermal sulfur from the heater. For this reason, long-term repeated durability can be ensured by an ordinary heat-resistant resin or corrosion-resistant resin called fluororesin. Further, the central conductive rod 11k can be conductively connected to the porous metal body 11s with a small contact resistance.

<A 1st embodiment of a manufacturing method of cylindrical MEA>
4-8 shows 1st Embodiment of the manufacturing method of cylindrical MEA7. FIG. 4 is a flowchart according to the method for manufacturing the cylindrical MEA 7 according to the first embodiment. Moreover, (a)-(h) of FIGS. 5-8 is a figure which shows each process of the said manufacturing method.

  In this embodiment, cylindrical MEA is manufactured using a rubber press molding method. The rubber press molding method is a technique in which a powder material or a preformed powder material is filled in a rubber mold, and a high hydrostatic pressure is applied from the outer periphery to form a homogeneous powder compact.

  In the present embodiment, a rubber mold 21 having a cylindrical mold part is prepared (S101). As shown in FIG. 5 (a), a cylindrical mold portion is formed in the rubber mold 21, and a round bar-shaped central mold portion 22 formed of a hard material such as metal at the center portion. Is inserted, and a cylindrical mold part 21 a is formed by the outer peripheral surface of the central mold part 22 and the inner peripheral surface of the rubber mold 21. In the present embodiment, the powder material constituting the solid electrolyte layer 1 is filled in the cylindrical mold part 21a (S102). Thereafter, hydrostatic pressure is applied to the outer peripheral portion of the rubber mold 21 to compress the powder material, thereby forming the cylindrical molded body 1a (S103).

  When the hydrostatic pressure acting on the rubber mold 21 is removed, the rubber mold 21 tries to return to the form before compression by elasticity. At this time, the molded body 1a is also expanded in diameter by a kind of spring bag. In the present embodiment, by utilizing the diameter increase of the cylindrical molded body 1a, the inner peripheral portion of the compression molded body 1a (first unfired cylindrical portion) in the rubber mold and the central mold portion. A cylindrical gap is formed between the outer peripheral portion 22 and the cylindrical gap is used as the second cylindrical mold portion 23 (S104). In order to separate the compression molded body (first unsintered cylindrical portion) from the outer peripheral surface of the rod-shaped mold portion, it is preferable to apply a release agent or the like.

  Next, as shown in FIG. 6C, the second cylindrical mold part 23 is filled with a powder material constituting the first electrode layer 2 formed inside (S105). Thereafter, as shown in FIG. 6 (d), the first unfired cylindrical portion in which the powder material is first molded by applying hydrostatic pressure again to the rubber mold 21 filled with the powder material. The second unfired cylindrical portion 2a is formed by compression molding with 1a (S106).

  By the above process, a cylindrical body 7a is formed in which the unfired cylindrical portion 1a constituting the solid electrolyte layer and the second unfired cylindrical portion 2a constituting the first electrode layer (anode) are integrally formed. Then, as shown in FIG. 7E, the rubber mold 21 is taken out (S107). Then, as shown in FIG.7 (e), the process which cuts the front-end | tip part of the said cylindrical body 7a is performed, and the unfired cylindrical body 7a with which both ends were opened is formed.

  In the present embodiment, next, a silver paste coating step for forming the porous conductive layer 11g on the inner peripheral portion of the first electrode layer (anode) is performed (S108).

Silver paste that becomes porous after being applied and dried (fired) is commercially available, and for example, DD-1240 manufactured by Kyoto Elex Co., Ltd. can be used. By making the silver paste coating layer 11g porous, many ammonia molecules NH ₃ enter the porous pores and come into contact with the catalyst in the anode so that an anode reaction is likely to occur.

  In order to increase the efficiency of the gas decomposition reaction, the porosity of the silver paste coating layer 11g is preferably set to 20 to 80%. When the porosity is 20% or less, it becomes difficult to guide the gas into the conductive paste coating layer, and the efficiency cannot be increased. On the other hand, when the porosity is 80% or more, it is difficult to ensure sufficient conductivity and the strength of the coating layer cannot be ensured. Furthermore, it is more preferable to set the porosity to 40 to 60%.

  The thickness of the silver paste coating layer 11g can be set to 5 to 300 μm. If it is 5 μm or less, the entire area of the Ni mesh sheet 11a cannot be uniformly brought into contact with the silver paste coating layer 11g, and it is difficult to ensure sufficient conductivity. On the other hand, when the thickness is 300 μm or more, it is difficult to form a paste coating layer having a sufficient porosity. In order to ensure conductivity and porosity, it is more preferable to provide a silver paste coating layer 11g having a thickness of 5 to 100 μm.

  The method for forming the silver paste coating layer 11g is not particularly limited. The silver paste coating layer is formed by a dipping method in which the unfired cylindrical body 7a is dipped in an immersion layer filled with silver paste, a technique of inserting a coating nozzle for injecting the silver paste into the unfired cylindrical body 7a, or the like. 11 g can be formed.

  Further, the method for forming the silver paste coating layer 11g to be porous is not particularly limited. In order to ensure the required porosity described above, a silver paste containing a predetermined amount of a binder that disappears at a predetermined temperature can be employed. In order to prevent shrinkage of the conductive paste coating layer when the binder disappears, it is preferable to add a sublimation binder. For example, it is preferable to employ a silver paste containing a naphthalene binder. The silver paste coating layer 11g is made porous by removing the binder by heating to a predetermined temperature, and further, the silver particles are baked at an elevated temperature, thereby making the porous silver paste coating layer 11g. Is formed.

  The range in which the silver paste coating layer 11g is provided is not particularly limited, but it is preferable to provide the silver paste coating layer 11g on the entire surface of the anode 2. By forming the silver paste coating layer 11g on the entire surface of the anode 2, even when a part of the Ni mesh sheet is separated from the silver paste coating layer, the current collecting performance in the anode 2 is not lowered.

  After the silver paste coating layer 11g is provided, the binder in the silver paste is removed and made porous by holding the silver paste at a temperature at which the silver paste is made porous in a baking furnace, and the temperature is further increased to increase the temperature. The unfired cylindrical part and the second unfired cylindrical part are fired (S109). After the silver paste is made porous at a temperature of about 400 ° C. for about 60 minutes, it is about 800 ° C. for firing the first green cylindrical portion and the second green cylindrical portion. The firing process is carried out by raising the temperature. Thereby, the cylindrical fired body 7b shown in FIG. 8 (g) is formed.

  In the present embodiment, a second electrode layer forming step of separately forming the second electrode layer (cathode) 5 on the outer peripheral portion of the cylindrical fired body 7b is performed (S110). The method for forming the second electrode layer (cathode) is not particularly limited. For example, a paste containing a powder material constituting the cathode can be applied and fired again. Thereby, cylindrical MEA is formed. In addition, the second electrode layer can be formed by a technique such as thermal spraying.

  In the manufacturing method of the cylindrical MEA according to the above-described embodiment, the first unfired cylindrical portion 1a that constitutes the solid electrolyte layer 1 and the second that constitutes the inner first electrode layer (anode) 2. The unfired cylindrical portion 2 a can be continuously performed using one rubber mold 21. For this reason, manufacturing man-hours and manufacturing costs can be reduced.

  Further, the first unfired cylindrical portion and the second unfired tubular portion can be integrally laminated by applying a large hydrostatic pressure. In addition, the first unfired cylindrical part and the second unfired cylindrical part are fired in a single firing step. For this reason, the solid electrolyte layer 1 and the first electrode layer 2 are baked in close contact with each other, and the conductivity between them can be sufficiently secured. For this reason, there is no possibility that the performance is lowered due to a decrease in conductivity between the solid electrolyte layer and the first electrode layer.

  In the first embodiment, the second green cylindrical portion 2a constituting the first electrode layer (anode) 2 is formed on the inner peripheral portion of the first green cylindrical portion constituting the solid electrolyte layer 1. However, it is also possible to form the second non-fired cylindrical part constituting the second electrode layer (cathode) on the outer peripheral part of the non-fired cylindrical part 1a constituting the solid electrolyte layer.

  In this case, when the hydrostatic pressure of the rubber mold is released after the first unfired cylindrical part is formed, the inner periphery of the rubber mold and the first unfired cylindrical part are interposed. A gap is formed, and the powder material constituting the second unfired cylindrical portion can be filled using the gap as a cylindrical mold space. In order to separate the inner peripheral surface of the rubber mold from the outer peripheral surface of the first unsintered cylindrical portion, it is preferable to apply a release agent to the inner peripheral surface of the rubber mold. In the above-described embodiment, the example in which the unsintered cylindrical part constituting the solid electrolyte layer is formed first is shown. However, the unsintered cylindrical part constituting the first electrode layer (anode) is first shown. Then, an unsintered cylindrical part constituting the solid electrolyte layer can be formed on the outer peripheral part. Alternatively, the unsintered cylindrical part constituting the second electrode layer (cathode) can be formed first, and then the unsintered cylindrical part constituting the solid electrolyte layer can be formed on the inner peripheral part. .

  The powder material that constitutes each of the unsintered cylindrical portions is selected according to the material that constitutes the solid electrolyte layer and the electrode layer.

  As the powder material constituting the solid electrolyte layer 1, a solid oxide, molten carbonate, phosphoric acid, solid polymer, or the like can be used. Solid oxides are preferred because they can be miniaturized and are easy to handle. Examples of the solid oxide 1 include oxygen ion conductive SSZ (scandium stabilized zirconia), YSZ (yttrium stabilized zirconia), SDC (samarium stabilized ceria), LSGM (lanthanum gallate), GDC (gadria stabilized ceria). It is good to use. Proton conductive barium zirconate can also be used. Each said powder material can be baked by hold | maintaining at 1000 degreeC-1600 degreeC for about 30 minutes-180 minutes by air | atmosphere atmosphere.

  The first electrode layer (anode) 2 can be formed as a fired body mainly composed of a metal particle chain body that is oxidized on the surface and has an oxide layer, and an oxygen ion conductive ceramic. As oxygen ion conductive ceramics, SSZ (scandium stabilized zirconia), YSZ (yttrium stabilized zirconia), SDC (samarium stabilized ceria), LSGM (lanthanum gallate), GDC (gadria stabilized ceria), etc. should be used. Can do.

  When adopting the above SSZ, it is preferable to use one having an average diameter of about 0.5 μm to 50 μm. The firing step can be performed by holding at 1000 ° C. to 1600 ° C. for about 30 minutes to 180 minutes in an air atmosphere. The average diameter of the raw material powder of SSZ is preferably about 0.5 μm to 50 μm. The compounding ratio between the surface-oxidized metal particle chain and SSZ is in the range of 0.1 to 10 in terms of mol ratio.

  The metal of the metal particle chain is preferably nickel (Ni) or Ni containing iron (Fe). More preferably, Ti contains a trace amount of about 2 to 10000 ppm.

  The metal particle chain is preferably produced by a reduction precipitation method. The reduction precipitation method of the metal particle chain is described in detail in JP-A No. 2004-332047. The average diameter D of the metal particle chain contained in the first electrode layer (anode) 2 is preferably in the range of 5 nm to 500 nm. The average length L is preferably in the range of 0.5 μm or more and 1000 μm or less. The ratio between the average length L and the average diameter D is preferably 3 or more. However, it may have dimensions outside these ranges.

  The second electrode layer (cathode) 5 is formed from a fired body mainly composed of oxygen ion conductive ceramics. As the oxygen ion conductive ceramic in this case, LSM (lanthanum strontium manganite), LSC (lanthanum strontium cobaltite), SSC (samarium strontium cobaltite), or the like can be used. These powder materials can also be fired under the same conditions as described above.

<2nd Embodiment which concerns on the manufacturing method of cylindrical MEA>
9 to 11 show a second embodiment of the method for manufacturing the cylindrical MEA 7. FIG. 9 is a flowchart according to the manufacturing method of the cylindrical MEA 7 according to the second embodiment. Moreover, (a)-(f) of FIGS. 10-11 is a figure which shows each process of the said manufacturing method.

  The manufacturing method according to the second embodiment manufactures a cylindrical MEA using a sacrifice mold part. By molding the powder using the sacrificial mold part and eliminating the mold part before firing, it becomes possible to mold a complicated shape or a difficult-to-mold shape. Usually, the sacrificial mold part is formed from a resin material that sublimes when heated to a predetermined temperature or higher, and can be formed using a binder resin or the like used when molding powder.

  As shown in FIG. 10A, in this embodiment, a rod-shaped sacrificial mold portion 42 corresponding to the internal space of the cylindrical MEA is employed (S201). The rod-shaped sacrificial mold portion 42 can be formed of a resin material that sublimates and disappears at a predetermined temperature or higher, such as polyacetal resin.

  A slurry containing a powder material constituting the first electrode layer (anode) 2 is applied to the outer periphery of the rod-shaped sacrificial mold portion 42 with a predetermined thickness (S202), and then dried (S203). An unfired cylindrical portion 2a is formed.

  Next, as shown in FIG. 10B, a slurry containing a powder material constituting the solid electrolyte layer 1 is applied to the outer periphery of the first unfired cylindrical portion 2a (S204) and then dried. Thus (S205), the second unfired cylindrical portion 1a is formed.

  The rod-shaped sacrificial mold portion 42 is heated by heating the first unfired cylindrical portion 2a and the second unfired cylindrical portion 1a, which are stacked, together with the rod-shaped sacrificial mold portion 42 in a furnace. A sacrificial mold part disappearing step is performed to eliminate (S206). Thereby, as shown in FIG.10 (c), the unsintered cylindrical body 7a in which the 1st non-fired cylindrical part 2a and the said 2nd non-fired cylindrical part 1a were integrally molded is formed. .

  Thereafter, the unfired cylindrical portion 1a. 2a is heated to a temperature at which the powder constituting the unfired cylindrical portion 1a. 2a is fired (S207), and a fired cylindrical body 7b including the solid electrolyte layer 1 and the first electrode layer (anode) 2 shown in FIG. 11D is formed.

  Next, as shown in FIG. 11 (e), as in the first embodiment, the second electrode layer is formed to form the second electrode layer (cathode) 5 on the outer periphery of the fired cylindrical body 7b. Step (S208) is performed.

  Further, as shown in FIG. 11 (f), a silver paste constituting a conductive layer is applied to the inner surface of the first electrode layer 2 (S209) and is made porous (S210). Is formed.

  In the second embodiment, molding can be performed simply by laminating the material constituting the cylindrical MEA on the outer periphery of the sacrificial mold portion 42, so that the number of manufacturing steps can be reduced and the manufacturing cost can be reduced.

  In the present embodiment, the first unfired cylindrical portion and the second unfired tubular portion are formed by applying a slurry containing fired powder. It is also possible to use a molding technique in which a material corresponding to the part and the mold corresponding to the second unfired cylindrical part are filled. For example, a two-color injection molding method in which powder is mixed and melted with a binder and then injected can be employed.

<Third embodiment according to manufacturing method of tubular MEA>
12 and 13 show a third embodiment of the present invention. This embodiment is also performed using a sacrifice mold part that disappears by a predetermined operation.

  As shown in FIG. 12 (a), in this embodiment, a rod-shaped member 42a having a heat resistance higher than the firing temperature of the powder material constituting the cylindrical MEA, and a predetermined thickness on the outer periphery of the rod-shaped member 42a. Molding is performed using a rod-shaped center mold portion 42 including the formed sacrificial layer 42b.

  The rod-shaped member 42a can be formed of ceramics having high heat resistance. The sacrificial layer 42b can be formed using a resin material that constitutes the sacrificial mold part employed in the second embodiment.

  As shown in FIG. 12B, a slurry containing a powder material constituting the first electrode layer 2 is applied to the outer peripheral portion of the central mold portion 42 with a predetermined thickness and dried. The unfired cylindrical part 2a is formed.

  Moreover, as shown in FIG.12 (c), the slurry containing the powder material which comprises the solid electrolyte layer 1 is apply | coated to the outer peripheral part of the said 1st non-baking cylindrical part 2a by predetermined thickness, and it is made to dry. Thus, the second unfired cylindrical portion 1a is formed.

  In the present embodiment, as shown in FIG. 12 (d), a slurry containing a powder material constituting the second electrode layer is formed at a predetermined thickness on the outer peripheral portion of the second unfired cylindrical portion 1a. The third unfired cylindrical portion 5a is formed by applying and drying.

  After that, as shown in FIG. 13 (e), the center mold portion 42 is attached to the unsintered cylindrical body 7a composed of the unfired cylindrical portions 2a, 1a and 5a formed in a stacked manner. The sacrificial layer 42b disappears by heating to a predetermined temperature. In this state, a gap 43 corresponding to the sacrificial layer 42b is formed between the rod-shaped member 42a and the unsintered cylindrical portion 7a. Therefore, the rod-shaped member 42 is pulled out and the unsintered tube The body 7a can be fired separately.

  In the present embodiment, as shown in FIG. 13 (f), each of the unfired cylindrical portions is further heated in a state where the unfired cylindrical portions 2a, 1a, 5a are held by the rod-shaped member 42a. 2a, 1a and 5a are fired. As a result, a fired cylindrical body 7b including the fired three layers 2, 1, 5 is formed.

  Thereafter, as shown in FIG. 13 (g), the rod-shaped member 42a is extracted from the fired cylindrical body 7b to form a cylindrical MEA 7.

  In the present embodiment, the solid electrolyte layer 1 and the unfired cylindrical portions 2a, 1a, 5a constituting the first electrode layer 2 and the second electrode layer 5 can be integrally formed continuously. Moreover, the unfired cylindrical body 7a including the unfired cylinder portions 2a, 1a, and 5a constituting each layer can be fired in a single firing step. For this reason, while being able to reduce a manufacturing man-hour, manufacturing cost can be reduced.

  Moreover, since the rod-shaped mold part 42 provided with the sacrificial layer 42b is adopted, each of the above steps can be performed with the rod-shaped member 42a attached to the molded body. For this reason, handling in each process can be performed easily. Furthermore, when forming a long cylindrical MEA, it is possible to prevent distortion and breakage during the process.

  12 and 13 do not show the step of providing the porous conductive layer, it can be formed by the same method as in the first embodiment and the second embodiment.

  In the embodiment described above, the present invention is applied to a method for manufacturing a gas decomposition element for the purpose of removing gas. However, a gas decomposition element that is not mainly used for removing gas and a tubular MEA for an electrochemical reaction apparatus are manufactured. Applicable to the method. For example, it can also be used in a method for manufacturing a cylindrical MEA constituting a fuel cell or the like.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention disclosed above are merely examples, and the scope of the present invention is not limited to these embodiments. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  By the manufacturing method according to the present invention, a gas decomposition element having a low running cost, a small size, and a high performance can be manufactured with a small number of manufacturing steps and a low cost.

DESCRIPTION OF SYMBOLS 1 Solid electrolyte layer 2 1st electrode layer (anode)
5 Second electrode layer (cathode)
7 Tubular MEA
DESCRIPTION OF SYMBOLS 1a 1st unbaking cylindrical part 2a 2nd unbaking cylindrical part 7a Unbaking cylindrical body 7b Baking cylindrical body 11g Silver paste application layer (conductive paste application layer)

Claims (12)

A cylindrical solid electrolyte layer, the solid first electrode layer and the second electrode layer and comprises a formed tubular MEA of the electrolyte layer are laminated so as to sandwich the inner and outer (Membrane Electrode Assembly), Rubber A method of manufacturing a tubular MEA that is molded using a press molding method ,
Filled with a predetermined powder material into a cylindrical pressure rubber mold provided with a central mold part that fills the internal space of the first unfired cylindrical part constituting one of the solid electrolyte layer or the electrode layer A first molding step for molding by pressurizing ,
By releasing the pressure, the inner diameter of the pressure rubber mold and the first unfired cylindrical part is expanded, and the outer peripheral part of the central mold part and the first unfired tubular form A mold space forming step of forming a cylindrical mold part between the parts,
A second green cylindrical portion constituting the solid electrolyte layer or the other one of the electrode layers is formed by filling the cylindrical mold portion with a predetermined powder material and pressurizing again . 2 molding steps;
The manufacturing method of cylindrical MEA including the baking process which bakes the cylindrical body provided with the said 1st unbaking cylindrical part and the said 2nd unbaked cylindrical part, and forms a cylindrical baking body. A cylindrical solid electrolyte layer, the solid first electrode layer and the second electrode layer and comprises a formed tubular MEA of the electrolyte layer are laminated so as to sandwich the inner and outer (Membrane Electrode Assembly), Rubber A method of manufacturing a tubular MEA that is molded using a press molding method ,
Filled with a predetermined powder material into a cylindrical pressure rubber mold provided with a central mold part that fills the internal space of the first unfired cylindrical part constituting one of the solid electrolyte layer or the electrode layer A first molding step for molding by pressurizing ,
By releasing the pressure, the diameter of the pressure rubber mold is expanded, and a cylindrical mold portion is provided between the inner periphery of the pressure rubber mold and the outer peripheral portion of the first unfired cylindrical portion. Mold space forming step to form
A second green cylindrical portion constituting the solid electrolyte layer or the other one of the electrode layers is formed by filling the cylindrical mold portion with a predetermined powder material and pressurizing again . 2 molding steps;
The manufacturing method of cylindrical MEA including the baking process which bakes the cylindrical body provided with the said 1st unbaking cylindrical part and the said 2nd unbaked cylindrical part, and forms a cylindrical baking body.
A third forming step of laminating and forming a third unfired cylindrical portion constituting the solid electrolyte layer and the remaining one of the electrode layers using a predetermined powder material;
The cylinder according to claim 1 or 2, wherein, in the firing step, the first unfired cylindrical part, the second unfired cylindrical part, and the third unfired cylindrical part are fired. Of manufacturing MEA. In the first molding step and the second molding step, the first unfired cylindrical part constituting the solid electrolyte layer and one electrode formed inside the first unfired cylindrical part And forming a layer,
The electrode layer formation process which forms the other electrode layer in the outer peripheral part of the said solid electrolyte layer after the said baking process which bakes the cylindrical body provided with these non-baking cylindrical parts in Claim 1 or Claim 2 The manufacturing method of cylindrical MEA of description. The cylinder according to any one of claims 1 to 4 , further comprising a conductive layer forming step of forming a porous conductive layer on a surface of the first electrode layer and / or the second electrode layer. Of manufacturing MEA. A method of manufacturing a cylindrical MEA (Membrane Electrode Assembly) comprising a cylindrical solid electrolyte layer, and a first electrode layer and a second electrode layer laminated so as to sandwich the solid electrolyte layer from inside and outside. And
1st shaping | molding which shape | molds the 1st unbaking cylindrical part which comprises one of the said solid electrolyte layer or the said electrode layer in the outer peripheral part of the rod-shaped sacrificial die part which can be lose | disappeared by performing a predetermined process Process,
The outer periphery of the first green cylindrical portion, and a second forming step of forming a second unfired tubular portion which constitutes the other one of the solid electrolyte layer or the electrode layer,
A sacrificial mold part disappearing step of eliminating the rod-shaped sacrificial mold part,
A method for manufacturing a tubular MEA, comprising a firing step of firing a tubular body including the first unfired tubular portion and the second unfired tubular portion to form a tubular fired body. A method of manufacturing a cylindrical MEA (Membrane Electrode Assembly) comprising a cylindrical solid electrolyte layer, and a first electrode layer and a second electrode layer laminated so as to sandwich the solid electrolyte layer from inside and outside. And
The outer periphery of the rod-shaped sacrificial portion which can be eliminated by performing a predetermined process, a first forming step of forming a first unfired tubular portions constituting one of said electrode layer,
The outer periphery of the first green cylindrical portion, and a second forming step of forming a second unfired tubular portion constituting the solid electrolyte layer,
The outer peripheral portion of the second unsintered tubular portion, and a third forming step of forming a third unfired tubular portion which constitutes the remaining one of the electrode layers,
A sacrificial mold part disappearing step of eliminating the rod-shaped sacrificial mold part,
A firing step of firing a tubular body including the first unfired tubular portion, the second unfired tubular portion, and the third unfired tubular portion to form a tubular fired body; The manufacturing method of cylindrical MEA. The method for producing a cylindrical MEA according to claim 6 or 7 , comprising a conductive layer forming step of forming a porous conductive layer on a surface of the first electrode layer and / or the second electrode layer. . A gas decomposing element comprising a cylindrical MEA manufactured by the manufacturing method according to any one of claims 1 to 8 . It said first electrode layer and / or the second electrode layer, characterized in that the metal particles chain composed mainly of nickel (Ni), a sintered body containing an ion conductive ceramic, wherein Item 10. The gas decomposition element according to Item 9 . The gas decomposition element according to claim 9 or 10 , wherein the solid electrolyte has oxygen ion conductivity or proton conductivity. Comprises a gas decomposing device as claimed in any one of claims 11 請 Motomeko 9, the power generation device.

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