JP2010247034A - Gas abatement device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas detoxifying apparatus which is (1) miniaturized and capable of detoxifying a harmful gas to a harmless level efficiently and (2) operable at a low running cost. <P>SOLUTION: The gas detoxifying apparatus includes: a flow path A1 to which a gas containing a chemical component is introduced, and that the anode 2 of an MEA faces; and a conductive porous body 11 which comes in contact with the anode so as to serve as an anode collector and has continuous pores arranged so as to occupy the flow path A1. The conductive porous body includes an electrode contact porous sheet 11s in contact with the electrode of the MEA and a non-contact porous sheet 11t not in contact with the electrode of the MEA, and the electrode contact porous sheet is finer than the non-contact porous sheet. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gas abatement apparatus, and more particularly to a gas abatement apparatus that can efficiently decompose harmful gas such as ammonia contained in exhaust gas with low pressure loss. is there.

Many proposals have been made on a method of using a catalyst for decomposition of ammonia, particularly on a catalyst (Patent Documents 1 to 5). For example, porous carbon particles containing a transition metal, a manganese composition, an iron-manganese composition (Patent Document 1), a chromium compound, a copper compound, a cobalt compound (Patent Document 2), and a three-dimensional network structure made of alumina. Platinum (patent document 3) and the like have been published. In the method of decomposing ammonia by a chemical reaction using the above catalyst, generation of nitrogen oxides NOx can be suppressed. Furthermore, a method of promoting thermal decomposition of ammonia more efficiently at 100 ° C. or less by using manganese dioxide as a catalyst has been proposed (Patent Documents 4 and 5).
As described above, there is a detoxification device whose main purpose is to decompose ammonia, which is an odor component in waste gas, down to the ppm order, unlike the case where it is intended to decompose a large amount of ammonia. For example, exhaust gas in the production of compound semiconductors usually contains ammonia and the like, and in order to completely remove the off-flavor of ammonia, it is necessary to remove it to the order of ppm. For this purpose, the exhaust gas of the semiconductor production line is passed through a scrubber, causing the moisture containing the chemical to absorb the harmful gases therein and then released into the atmosphere.
In addition, in order to obtain an inexpensive running cost without input of energy, chemicals, etc., there has been proposed an exhaust gas treatment of a semiconductor manufacturing apparatus using a hydrogen-oxygen fuel cell decomposition method (Patent Document 6).

Japanese Patent Laid-Open No. 11-347535 JP-A-53-11185 JP 54-10269 A JP 2006-231223 A JP 2006-175376 A JP 2003-45472 A

  According to the method (patent documents 1 to 5) based on the thermal decomposition reaction using the above catalyst, ammonia can be decomposed. Scrubbers can also be detoxified to the order of ppm, such as ammonia. However, the above method has a problem that it requires external energy (fuel), requires periodic replacement and maintenance of the catalyst, and has a high running cost. In addition, the apparatus becomes large and, for example, when it is additionally provided in existing equipment, the arrangement may be difficult. For the hydrogen-oxygen fuel cell decomposition method, if exhaustion is thoroughly done to the ppm order, a long exhaust gas flow path is required at the fuel electrode, and an increase in the size of the device is inevitable to prevent an increase in pressure loss. . In Japan, an increase in the size of the apparatus often causes great disadvantages in practice.

  An object of the present invention is to provide a gas abatement apparatus that can (1) be small, efficiently remove harmful gas to a harmless level, and (2) operate at a low running cost.

  The gas abatement apparatus of the present invention includes a MEA (Membrane Electrode Assembly) composed of a pair of electrodes and an electrolyte sandwiched between the pair of electrodes, and detoxifies chemical components in the gas by an electrochemical reaction. Device. This gas abatement apparatus is in contact with and occupies a flow path in which a gas containing a chemical component is introduced, the flow path facing the electrode of the MEA, and the current collector of the electrode facing the MEA. A conductive porous body having continuous pores, the conductive porous body having an electrode-contacting porous sheet in contact with the MEA electrode, and a non-contacting porous sheet not in contact with the MEA electrode, The contact porous sheet is characterized by being finer than the non-contact porous sheet.

  According to the above configuration, since the current collector of the electrode that becomes the site of the electrochemical reaction of decomposition is formed of a fine electrode contact sheet, a reliable current collection can be obtained, and the electrochemical reaction described above It is possible to facilitate conduction of electrons involved in the. Moreover, since the part which is not in contact with the electrode is relatively rough, pressure loss is not increased. As a result, a low pressure loss can be realized with a small apparatus while ensuring good reaction efficiency. In addition, the above gas abatement device does not require maintenance, and in the electrochemical reaction, no input power is required in the case of a power generation reaction, but in the electrolysis reaction, the input power is small and the running cost is low. Is suppressed.

  The above MEA is used as a first MEA, and further includes a second MEA. The first MEA and the second MEA have electrodes of the same polarity facing each other and sandwich a flow path, The first electrode contact porous sheet in contact with the first MEA, the second electrode contact porous sheet in contact with the second MEA, and the non-contact porous sheet sandwiched between the first and second electrode contact porous sheets Can be configured. This makes it possible to remove harmful components to a very low concentration by using a relatively short electrode length, while constituting a double-sided electrode flow path (same polarity electrode / flow path / same polarity electrode). It is possible to achieve smoothing of electronic conduction (low electrical resistance) and low pressure loss.

  The flow path may be provided with at least one folded portion so as to meander between the introduction of gas and the exhaust. This makes it possible to ensure a sufficient reaction length (electrode length) while being small by taking advantage of the morphological feature of the MEA that is planar. The number of folds is limited by the allowable pressure loss.

  50% or more and 90% or less of the thickness of the conductive porous body in the decomposition chamber can be formed of a non-contact porous sheet. This makes it possible to appropriately balance the electronic conductivity with respect to the electrode at the decomposition site and the pressure loss. If the thickness of the non-contact porous sheet is less than 50% of the conductive porous body, the pressure loss is too high, which impairs energy efficiency. On the other hand, if it exceeds 90%, the electronic conductivity deteriorates and the rate of the electrochemical reaction for decomposition is reduced.

  According to the gas abatement apparatus of the present invention, (1) it is small and efficient, it can remove harmful gas to a harmless level, and (2) it can be operated at a low running cost.

It is a perspective view of the external appearance of the ammonia decomposition apparatus in Embodiment 1 of this invention. It is a fragmentary sectional view of the ammonia decomposition device of FIG. It is an enlarged view containing MEA of the ammonia decomposition apparatus of FIG. It is a figure for demonstrating the electrochemical reaction of ammonia decomposition. It is a figure for demonstrating the electrochemical reaction in an anode. It is a figure explaining the electrochemical reaction in the both-sides electrode flow path of the ammonia decomposition apparatus of this Embodiment. It is a figure explaining the electrochemical reaction of ammonia decomposition | disassembly in a one-side electrode flow path. It is a figure for demonstrating the ammonia decomposition apparatus in the modification of Embodiment 1. FIG. It is a figure for demonstrating the ammonia decomposition apparatus in Embodiment 2 of this invention. FIG. 10 is a partial cross-sectional view of the ammonia decomposition apparatus in FIG. 9.

(Embodiment 1-Both-side electrode flow path-)
FIG. 1 is a diagram showing an ammonia decomposition apparatus 10 which is a gas abatement apparatus in Embodiment 1 of the present invention. In the ammonia decomposing apparatus 10, ammonia in the ammonia-containing gas is decomposed by an electrochemical reaction, particularly a fuel cell reaction. An ammonia-containing gas is introduced from the inlet 61 into the fuel electrode (hereinafter referred to as the anode) of the fuel cell, and air is introduced from the inlet 71 into the air electrode (hereinafter referred to as the cathode). By the electrochemical reaction described below, ammonia in the ammonia-containing gas is decomposed into nitrogen and water and released from the outlet 62 together with other gases. In addition, oxygen also participates in the electrochemical reaction with respect to air, and the remaining nitrogen and the like are released from the outlet 72. After ammonia is decomposed, the ammonia concentration in the gas discharged from the outlet 62 is detoxified to the order of ppm or less. Thus, the abatement apparatus is different from the fuel cell in that the decomposition target component in the gas associated with the fuel is decomposed to an extremely low concentration level. In fuel cells, attention is focused on power generation efficiency, and it is assumed that the concentration of components to be decomposed in gas is above a predetermined level. In the present embodiment, the component in the gas corresponding to the fuel is decomposed. However, the present invention is not limited to this. For example, the gas corresponding to the air is not air itself, but another component (for example, NOx) or the component You may decompose | disassemble the said component in the other gas or air containing.
In FIG. 1, electric power can be taken out from an anode terminal 11a that is conductively connected via an anode and an anode current collector (not shown) and a cathode terminal 12a that is conductively connected via a cathode and a cathode current collector. The ammonia decomposing apparatus 10 is heated to about 700 ° C. to 900 ° C. in order to obtain a practical electrochemical reaction rate. You may supply the electric power taken out from the cathode terminal 12a and the anode terminal 11a to this heater for heating and a heating control apparatus (microcomputer). Whatever load is applied between the cathode terminal 12a and the anode terminal 11a, in order to cause and sustain the electrochemical reaction of ammonia decomposition, electrons generated at the anode are transferred from the anode terminal 11a to the cathode terminal. It is necessary to conduct to 12a through a load.

  FIG. 2 is a cross-sectional view of the ammonia decomposition apparatus 10 shown in FIG. FIG. 3 is a partially enlarged view of the central portion. Two sheet-like MEAs are arranged across a flow path A1 occupied by the anode current collector 11 of a metal porous body. Since the channel A1 is sandwiched from above and below by the MEA anode 2, it is a double-sided electrode channel. The ammonia-containing gas introduced from the inlet 61 flows through the both-side electrode channel A1 while being in contact with the anode current collector 11. The anode current collector 11 is formed of a coarse metal porous body 11t and a finer metal porous body 11s. The fine metal porous body 11s is disposed in contact with the anode 2 of the MEA to constitute an electrode contact porous sheet, and the coarse metal porous body 11t is disposed at a central position therebetween to constitute a non-contact porous sheet. . In the ammonia decomposing apparatus 10 in the present embodiment, the metal porous body 11 that forms the anode current collector 11 occupying the both-side electrode flow path A1 is defined as the one having the coarse contact 11s that contacts the anode 2, and the coarser than that. It is characterized in that the object 11t is arranged in the center. The function of the anode current collector is substantially performed by the electrode contact porous sheet 11s. The non-contact perforated sheet 11t mechanically contacts the electrode contact perforated sheet 11s and may take part in the current collecting action depending on how the terminals are taken. For example, the anode terminal 11a is connected to the electrode contact perforated sheet 11s. It is preferable that the non-contact porous sheet 11t is directly connected and does not participate in the current collecting function in terms of suppression of electric resistance.

A flow path C _1/2 in contact with the cathode 3 is disposed outside the two MEAs, that is, on the side opposite to the flow path A1 on the anode side of the MEA. The air introduced from the inlet 71 flows in contact with the cathode current collector 12 in the two cathode-side flow paths C1 _{/ 2} . The anode current collector 11 and the cathode current collector 12 are brought into contact with the gas flowing through the flow paths occupied by the anode current collector 11 and the cathode current collector 12 to make the gas flow turbulent, and the gas is brought into good contact with the electrode of the MEA to perform an electrochemical reaction. Proceed efficiently. Of the anode current collector 11, the electrode contact porous sheet 11 s and the cathode current collector 12 are in conductive contact with the anode 2 and the cathode 3, respectively, to facilitate the transfer of electrons in the decomposition reaction (electrochemical reaction). . For this reason, the anode current collector 11 and the cathode current collector 12 are required to have electrical conductivity and air permeability, and in particular, the air permeability is required not to cause pressure loss. As a porous metal body having the above-mentioned characteristics, for example, there is one having continuous pores in which a triangular prism skeleton is connected in three dimensions. As a typical material thereof, for example, Celmet (registered trademark) manufactured by Sumitomo Electric Industries, Ltd. is used. be able to. In the anode current collector 11 according to the present embodiment, the electrode contact porous sheet 11s is mainly assigned to the multi-layer structure using the electrode contact porous sheet 11s and the non-contact porous sheet 11t, and the air permeability is not. The contact porous sheet 11t is relatively large. In summary, the following effects can be obtained.
(1) Since the conductive contact with the anode 2 is performed by the fine electrode contact porous sheet 11s, a conductive contact with low electrical resistance can be obtained. As a result, the rate of decomposition can be improved without hindering the exchange of electrons in the electrochemical reaction of decomposition.
(2) An increase in pressure loss can be suppressed by disposing the coarse metal porous sheet 11t in the electrode non-contact portion, particularly in the center of the cross section, of the flow path A1.

FIG. 4 is an enlarged cross-sectional view for explaining an electrochemical reaction including the MEA and the flow paths A1 and C1 _{/ 2} of FIGS. As described above, two MEAs are arranged across the flow path A1 occupied by the anode current collector 11. An ammonia-containing gas is passed through the flow path A1 and contacts the anode 2 to decompose ammonia. Further, the two flow paths C1 _/ 2 located outside the two MEAs are occupied by the cathode current collector 11, and air is introduced therein.

The MEA includes an electrolyte 1 and an anode 2 and a cathode 3 that sandwich the electrolyte 1. The electrolyte 1 may be anything as long as it has ionic conductivity, such as a solid oxide, molten carbonate, phosphoric acid, a solid polymer, and an electrolytic solution. Solid oxides are preferred because they can be miniaturized and are easy to handle. As the solid oxide, SSZ (scandium stabilized zirconia), YSZ (yttrium stabilized zirconia), SDC (samarium stabilized ceria), LSGM lanthanum gallate), or the like is preferably used.
The anode 2 is preferably a sintered body mainly composed of a metal particle chain 21 that has been oxidized on the surface and has an oxide layer, and an oxygen ion conductive ceramic 22. As the oxygen ion conductive ceramic 22, the above-described SSZ, YSZ, SDC, LSGM, or the like can be used.
The cathode 3 is a sintered body mainly composed of oxygen ion conductive ceramics 32 and silver (Ag) 33. As the oxygen ion conductive ceramic 32, it is preferable to use LSM (lanthanum strontium manganite), LSC (lanthanum strontium cobaltite), SSC (samarium strontium cobaltite) or the like. In the case of ammonia decomposition, a Ni particle chain having a surface oxidized and having an oxidized layer is not required as a catalyst for the cathode 3, but for decomposition of other chemical components, the surface of the sintered body forming the cathode is used for the surface. Ni grain chains that are oxidized and have an oxide layer may be included. The Ni grain chain is made of Ni as the metal of the metal grain chain and is relatively easy to manufacture and is known. Further, the conductive part (metal part covered with the oxide layer) of the Ni grain chain may be Ni alone, or Ni may contain Fe.

In this embodiment, the gas to be decomposed is ammonia (NH ₃ ), and the gas that supplies oxygen ions is air, that is, oxygen (O ₂ ). Ammonia introduced into the anode 2 undergoes a reaction (anode reaction) of 2NH ₃ + 3O ²⁻ → N ₂ + 3H ₂ O + 6e ⁻ . N ₂ + 3H ₂ O, which is the fluid after the reaction, is released from the anode. Further, oxygen in the air introduced to the cathode 3 undergoes a reaction of O ₂ + 2e ⁻ → 2O ²⁻ (cathode reaction). Oxygen ions reach the anode 2 from the LSM 32 in the cathode 3 through the solid electrolyte 1. Oxygen ions that have reached the anode 2 react with the ammonia and the ammonia is decomposed. The decomposed ammonia is released as nitrogen gas and water vapor (H ₂ O). Electrons e ⁻ generated at the anode 2 flow toward the cathode 3 through a load (not shown). As a result of the above reaction, a potential difference is generated between the anode 2 and the cathode 3, and the potential of the cathode 3 becomes higher than that of the anode 2.

FIG. 5 is a diagram for explaining ammonia decomposition in the anode 2. The anode 2 is a sintered body mainly composed of a Ni grain chain 21 with an oxide layer having an oxide layer 21b on the surface layer of the Ni grain chain 21a and an oxygen ion conductive ceramic 22. Ammonia in the gas has moved through the electrolyte 1 at a position where the oxygen ion conductive ceramics 22, the oxide layer 21b, and the Ni particle chain 21a are associated with each other in the anode 2 via the anode current collector. It reacts with oxygen ions O ²⁻ and decomposes. As a result of decomposition, nitrogen and water vapor are released. It is important that the anode current collector does not pass through ammonia to cause the above electrochemical reaction at the anode and not to increase pressure loss.
Electrons generated at the anode 2 reach the cathode 3 from the cathode current collector 12 made of a metal porous body via an external circuit or a load (see FIG. 4). Oxygen in the air introduced into the cathode current collector 12 passes through the continuous pores 12h and enters the pores 3h, and at the position where the silver particles 33 and the oxygen ion conductive ceramics 32 are associated with each other on the cathode 3. ^2- , and moves in the oxygen ion conductive ceramic 32 toward the solid electrolyte 1.

(Both-side electrode flow path)
Here, the operation of the both-side electrode flow path in the apparatus for removing harmful gas to an extremely low concentration will be described. As shown in FIG. 6, in the both-side electrode flow path A1, the anodes 2 of the two MEAs are positioned so as to face each other across the flow path A1 of the ammonia-containing gas. In this arrangement, ammonia is decomposed by causing an electrochemical reaction to proceed on the upper and lower walls, as shown in FIG. 4, because these walls are the anode 2 regardless of whether the upper wall or the lower wall defining the flow path A1. . In FIG. 6, the ammonia at the center of the height of the flow path A1 seems to pass through the flow path A1, but the flow path A1 is a coarse metal porous body (non-contact sheet) 11t of the anode current collector 11. Therefore, it is turbulent, flows toward the fine electrode contact sheet 11s, and participates in the electrochemical reaction at the anode 2.
FIG. 7 shows a structure shown for comparison, and shows a flow path A _1/2 when the same surface of the MEA is aligned on the same side and stacked in parallel as a one-side electrode flow path. In a structure in which MEAs are stacked in parallel so as to form a one-side electrode flow path, it is appropriate to compare with the flow path A1 in FIG. 6 assuming that there are two flow paths A _1/2 shown in FIG. . In the case of FIG. 7, ammonia flows through the flow path A _1/2 , but in the case of FIG. 7, it decomposes only at the upper wall, which is the anode 2, and does not decompose at the insulating partition sheet 13 constituting the lower wall, but simply contacts as gas To do. In the case where the MEA electrodes are aligned in parallel, an insulating partition sheet 13 is required for each MEA and its associated flow path for electrical insulation and separation of air and ammonia-containing gas. It becomes. There are two such channels A _1/2 .
Comparing the case where there is one channel A1 in FIG. 6 and the case where there are two channels A1 _/ 2 in FIG.
(1) If a large amount of ammonia is introduced into these flow paths, the total area of the decomposition site (anode 2) is the same in both cases, and the total amount of ammonia decomposed is not very different. For this reason, for example, when the power generation efficiency of the fuel cell is considered as a problem, both of them produce results that are not significantly different.
(2) However, when detoxifying (decomposing) ammonia to an extremely low concentration, for example, ppm order, the required length of MEA is due to the presence of ammonia flowing in contact with the wall (insulating partition sheet 13) without being reacted. It will be long. This is because there are walls that allow unreacted conditions. In order to detoxify to an extremely low concentration, it is necessary to peel off unreacted ammonia from the wall and to contact the opposite wall (anode 2). If there is no wall that remains unreacted, ammonia can pass through the wall freely, so that the decomposition reaction does not have to stagnate. That is, as in the flow path A1, the interval is doubled, but both the upper wall and the lower wall are the anodes 2. When the decomposition proceeds, there is no portion that does not react and contacts the wall. The required length of the MEA is shortened.
(3) Since the flow path A1 for flowing the ammonia-containing gas does not need to be provided with the insulating partition sheet 13 as compared with the two flow paths A _1/2 with the insulating partition sheet 13, the pressure loss is easily reduced. For this reason, it is advantageous also in terms of pressure loss.
According to the above (1) and (2), in the device that removes harmful components to an extremely low concentration level, the double-sided electrode structure has a great effect on downsizing the device, particularly shortening the flow path length. Moreover, (3) It is easy to suppress pressure loss.

(Modification of Embodiment 1-Both-side Electrode Channel / Multilayer Structure-)
FIG. 8 is a cross-sectional view of the abatement apparatus 10 in a modification of the first embodiment, and corresponds to FIG. 2 or FIG. In the configuration of the abatement apparatus of FIG. 2, the both-side electrode flow path A1 has only one layer, but in this modification, both-side electrode flow paths are arranged in multiple layers or two layers. In the abatement apparatus 10 having the multilayer arrangement of the both-side electrode flow paths A1, unit fuel cells are electrically connected in series between the flow path A1 of the ammonia-containing gas and the air flow path C _1/2. There is no need. This is a significant difference from the case where the fuel cell is used. When used as a fuel cell, there is no value as a battery at a very low voltage in which the unit cells are electrically connected in parallel. However, when used as a detoxifying device, the purpose is not to take out electric power. Therefore, it is preferable to electrically connect them in parallel and not use an insulating partition sheet or the like from the viewpoint of suppressing pressure loss. The multilayer arrangement of the both-side electrode flow path A1 can perform a process for excluding a large amount of ammonia-containing gas while suppressing pressure loss. For this reason, a small and efficient abatement apparatus can be obtained in combination with the above-described effect of reducing the channel length in one layer.

(Embodiment 2-Serpentine double-sided electrode flow path)
FIG. 9 is a diagram showing a flow path in the ammonia decomposing apparatus 10 which is a gas abatement apparatus in Embodiment 2 of the present invention. The flow path A1 has a turn-back portion T, and forms channels P1 to P7 that reciprocate alternately to increase the flow path length. The flow path A1 with the folded portion T is a flow path for introducing an ammonia-containing gas to the anode, and the metal porous body 11 having a metal plating body as a skeleton is disposed so as to occupy the flow path. The metal porous body 11 also serves as an anode current collector. As shown in FIG. 10, the metal porous body 11 includes a fine electrode contact sheet 11s in contact with the anode, and a non-contact sheet 11t disposed in the center of the flow path A1 without contacting the electrode. . Thereby, pressure loss can be suppressed while performing the electron transfer in the electrochemical reaction of ammonia decomposition smoothly.
The ammonia decomposition apparatus 10 is formed by laminating a plurality of MEAs, and each MEA is partitioned by an insulating partition sheet (not shown). Air is introduced into the cathode paired with the anode facing the flow path having the folded portion T shown in FIG. 2, but there is no folded portion in the flow path C _1/2 into which the air is introduced. However, a folded portion may be provided. Here, the flow path for introducing air will be described as having a turn-back portion T, as in the flow path for introducing ammonia-containing gas.
By having the turn-back portion T, the flow path length can be increased while the area of the MEA is small, and the ammonia concentration in the gas can be reduced to a harmless level, for example, on the order of ppm. The channel wall 15 separating the reciprocating channels should be as thin as possible in order to suppress pressure loss. In the flow path A1 shown in FIG. 9, the number of folded portions T, that is, the number of turns is six. As the number of turns increases, the length of the flow path becomes longer and the decomposition reaction can be caused to occur longer. However, since the pressure loss increases, it is preferable to make it within an allowable range.

The flow paths A1 and C1 _{/ 2} of the ammonia decomposing apparatus 10 shown in FIG. 10 have the same folded portion T as in FIG. 9 and are formed by channels P1 and the like that reciprocate alternately separated by the channel wall 15. In the present embodiment, anodes are arranged on both the upper and lower surfaces of the anode-side channel A1. That is, the two MEAs are such that the anodes 2 of the same polarity are opposed to each other, the flow path A1 is sandwiched between them, and the flow path A1 is a double-sided electrode flow path. The ammonia-containing gas introduced from the inlet 61 is introduced into the both-side electrode channel A1. Moreover, the air which is the other party gas is introduce | transduced into the cathode side flow path C1 _{/ 2} on the opposite side of each MEA. The cross-sectional area of the both-side electrode flow path A1 is larger than any of the cathode-side flow paths C1 _{/ 2} , as can be seen from the cross section of the channel P1 and the like. This makes it possible to suppress pressure loss while flowing a large amount of ammonia-containing gas whose concentration has been reduced to an extremely low level. Since the ammonia concentration is reduced to a very low level, the amount of air required for the electrochemical reaction is small. For this reason, the magnitude relation of a cross-sectional area as shown in FIG. 10 is brought about.

(Other embodiments)
1. In the above-described embodiment of the present invention, the case where the conductive porous body 11 occupying the both-side electrode flow channels in contact with the anode is formed by the fine electrode contact sheet 11s and the non-contact non-contact sheet 11t is illustrated. . However, the anode current collector disposed in the one-side electrode flow path may be disposed so that the finer one is in contact with the anode by using a fine conductive porous sheet and a coarse conductive porous sheet.
2. In the above-described embodiment of the present invention, the conductive porous body 11 occupying the flow path A1 in contact with the anode has been exemplified. However, the conductive porous body occupying the flow path for the flow path C _1/2 in contact with the cathode is You may form with a fine thing and a rough conductive porous body.
3. The gas abatement apparatus of the present invention can be used for all the abatement reactions R1 to R7 shown in Table 1. In the first embodiment, the reaction R1 has been described.

  As for ammonia detoxification, the reactions R2 to R4 in Table 1 are possible. Of these, the reaction R4 is not a fuel cell reaction but an electrolysis reaction. However, the reaction R4 is the same as that of the first embodiment in terms of an electrochemical reaction, except for the difference between taking out and supplying electric power. There are also VOC (Volatile Organic Compounds) detoxification and NOx detoxification. For all these electrochemical reactions, (1) arrange the electrodes of the same polarity so as to face each other across the both-side electrode flow channel, make the conductive porous sheet in contact with the electrodes of the same polarity fine, A non-contact conductive porous sheet can be used having a coarse mesh. (2) Moreover, you may use the electroconductive porous sheet of the same structure about a one-side electrode flow path. As a result, it can be operated at a low running cost, is small, and can efficiently remove harmful gases to harmless levels.

Next, the effect of the gas abatement apparatus of the present invention will be verified by examples. The present invention Example A1 has bilateral electrode channel A ₁ illustrated in the first embodiment of the present invention, using the ammonia decomposition apparatus shown in FIG. The metal porous body occupying both sides electrode channel A _1, Sumitomo Electric Industries, Ltd. of Celmet (R) was used in the composite layer. As the electrode contact sheet 11s in contact with the anode, a cermet having a hole diameter of 0.45 mm and a thickness of 0.5 mm was used, and a cermet having a hole diameter of 1.9 mm and a thickness of 2 mm was used for the central non-contact part 11t. The non-contact sheet thickness of 2 mm is about 67% of the flow path thickness of 3 mm.
For comparison, the other parts were the same as Example A1 of the present invention, and only a conductive porous sheet occupying both-side electrode channels was used as a single layer. The single-layer cermet had a thickness of 3 mm and a hole diameter of 1.9 mm.
After heating to 800 ° C., nitrogen gas containing 50% ammonia was passed through the ammonia decomposing apparatus, and the ammonia concentration at the outlet was measured. The results are shown in Table 2.

  According to Table 2, in Comparative Example B1, the ammonia concentration was 100 ppm, whereas in Invention Example A1, it was detoxified to 25 ppm and decomposed to a quarter concentration. This is because the conductive porous body that occupies the electrode flow paths on both sides is fine in the contact with the anode, and the central portion that is not in contact with the electrode is formed with a coarse conductive porous body. This is because pressure loss was suppressed while facilitating the transfer of electrons.

  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.

  According to the gas abatement apparatus of the present invention, (1) it is small and efficient, it can remove harmful gas to a harmless level, and (2) it can be operated at a low running cost. In particular, downsizing can be further promoted by dividing the grain of the conductive porous sheet that occupies the both-side electrode channels into multiple layers.

1 ion conductive electrolyte (solid oxide electrolyte), 2 anode, 3 cathode, 10 ammonia decomposition apparatus, 11 metal porous body (anode current collector), 11a anode terminal, 11s electrode contact porous sheet, 11t non-contact porous sheet, 12 metal porous body (cathode current collector), 12a cathode terminal, 13 insulating partition sheet, 15 channel wall, 21 metal particle chain, 21a metal particle chain core (metal part), 21b oxide layer, 22 anode Ion conductive ceramics (SSZ, etc.), 32 Cathode ion conductive ceramics (LSM, etc.), 33 Silver, 61 Ammonia-containing gas inlet, 62 outlet, 71 Air inlet, 72 outlet, A1, A _1/2 anode side flow path (ammonia-containing gas _channel), the cathode-side channel of the outer _{C 1/2} sides electrodes passage (air passage), P1 to 7 channel (serpentine passage).

Claims (4)

An apparatus comprising a MEA (Membrane Electrode Assembly) composed of a pair of electrodes and an electrolyte sandwiched between the pair of electrodes, and detoxifying chemical components in the gas by an electrochemical reaction,
A flow path in which a gas containing the chemical component is introduced and the MEA electrode faces;
A conductive porous body having continuous pores disposed so as to contact the electrode and occupy the flow path so as to be a current collector of the electrode facing the MEA;
The conductive porous body has an electrode contact porous sheet in contact with the electrode of the MEA, and a non-contact porous sheet not in contact with the electrode of the MEA,
The detoxifying device, wherein the electrode contact porous sheet has finer eyes than the non-contact porous sheet.   The MEA is used as a first MEA, and further includes a second MEA. The first MEA and the second MEA have electrodes of the same polarity facing each other and sandwich the flow path, and the conductive porous The body is sandwiched between the first electrode contact porous sheet in contact with the first MEA, the second electrode contact porous sheet in contact with the second MEA, and the first and second electrode contact porous sheets. The abatement apparatus according to claim 1, comprising a contact porous sheet.   3. The gas abatement apparatus according to claim 1, wherein the flow path is provided with at least one folded portion so as to meander between the introduction and exhaust of the gas. The abatement apparatus according to any one of claims 1 to 3, wherein 50% or more and 90% or less of the thickness of the conductive porous body in the flow path is formed by the non-contact porous sheet. .

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