JP4822494B2 - Electrochemical cell type chemical reactor - Google Patents

Description

  The present invention relates to a chemical reactor for performing a chemical reaction or energy conversion reaction of a substance to be treated. More specifically, for example, an electrochemical cell that efficiently purifies nitrogen oxides from combustion exhaust gas containing oxygen. It relates to a chemical reactor. The present invention relates to a technical field of a chemical reactor for performing a chemical reaction or an energy conversion reaction of a substance to be treated such as nitrogen oxides in exhaust gas. For example, a conventional chemical reactor is an automobile exhaust gas. When purifying exhaust gas with a large flow rate, the reaction volume is insufficient and the required performance cannot be obtained.When purifying nitrogen oxides in exhaust gas, oxygen molecules are adsorbed on the surface and the reactivity is reduced. Based on the fact that there was a problem of lowering, it became possible to drastically solve these problems, and to reactivate the chemical reactor with low power consumption, with high efficiency and continuously, the substance to be treated The present invention provides a new electrochemical cell type chemical reactor capable of treating the above.

  Currently, three-way catalysts are mainly used to purify nitrogen oxides generated from gasoline engines. However, in lean burn engines and diesel engines that can improve fuel efficiency, excess oxygen is present in the combustion exhaust gas, so in this three-way catalyst, the catalytic activity decreases drastically due to the adsorption of oxygen to the surface, It has been pointed out that there is a problem that nitrogen oxides cannot be purified efficiently.

  On the other hand, an attempt has been made to remove oxygen in an exhaust gas without adsorbing the catalyst surface by passing a current through the solid electrolyte membrane having oxygen ion conductivity. And as what has been proposed as a catalytic reactor, for example, by applying a voltage to a solid electrolyte sandwiched between electrodes, a method for removing surface oxygen and simultaneously decomposing nitrogen oxides into oxygen and nitrogen It has been proposed (see Patent Documents 1 and 2 and Non-Patent Document 1).

  However, in this type of method, when excess oxygen is present in the flue gas, the adsorption and decomposition reaction sites of coexisting oxygen and nitrogen oxide are composed of the same oxygen defects. The adsorption probability is remarkably low in view of the molecular selectivity and the ratio of the number of coexisting molecules. For this reason, it is necessary to pass a large amount of current in order to decompose the nitrogen oxide, thereby increasing the power consumption. There was a problem.

  In order to cope with such a problem, the present inventors have used a nanometer-sized through-hole around the same layer as an internal structure of a cathode in a chemical reactor, and an electron conductor and an ionic conductor are formed. By introducing a network-distributed structure that is in close contact with each other in the size of nanometers to micron, excess oxygen, which becomes an interfering gas when performing chemical reaction of the material to be treated, is reduced. A method for treating a substance to be treated with high power consumption has been developed (see Patent Document 3).

  However, in this type of method, it has been found that the current must be continuously supplied in order to remove the coexisting oxygen molecules, and the power consumption is insufficiently reduced. Therefore, as a result of further research aimed at solving these problems, the present inventors perform an adsorption-reduction reaction of nitrogen oxides in the working electrode layer located above the cathode in the chemical reaction section. By forming a local reaction field to enable chemical reaction efficiency, and after adsorbing a certain amount of oxygen molecules, the chemical reaction system is energized to ionize and remove oxygen molecules, It has been found that it can be reactivated (see Patent Document 4 and Patent Document 5).

  However, in this type of method, the portion that contributes to the reaction in the chemical reaction section is limited, and in the case of purification applications for large flow rates ranging from several hundred liters to 1000 liters / minute or more, such as automobile exhaust gas, the reaction volume However, there was a problem that required performance could not be obtained.

  In addition, when producing a chemical reactor, it is necessary to configure the chemical reactor without using noble metals and the necessity of performance for ion conductivity and electronic conductivity for the material constituting the chemical reaction part. Therefore, it has been required to enable low-temperature operation.

US Pat. No. 4,902,487 Japanese Examined Patent Publication No. 7-106290 Japanese Patent Application No. 2003-33646 Japanese Patent Application No. 2004-058028 Japanese Patent Application No. 2004-058029 Japan Surface Science Society, Environmental Catalyst, 1997, 167 pages, Kyoritsu Publishing Co., Ltd.

  In such a situation, in view of the prior art, the present inventors increased the reaction part in the chemical reaction part, and further, by using a solid electrolyte that can be densely sintered at a low temperature, As a result of studying the development of a new chemical reactor that makes it possible to produce a chemical reactor at a low temperature, a combination of an ion conducting phase and a reducing phase, or an ion conducting phase, and a cathode and an anode facing each other We have found that the intended purpose can be achieved by constructing the chemical reaction part with the assembly structure of the microelectrochemical cell consisting of the basic unit composed of the reduced phase in contact with the ion conducting phase or both. As a result, the present invention has been completed. That is, the present invention, for example, in the case where excess oxygen is present in the combustion exhaust gas, makes it easy to adsorb nitrogen oxides by pairing a selective adsorptive substance for oxygen molecules and nitrogen oxide molecules. A chemical reactor that reduces the amount of current required for the decomposition of oxides and at the same time reactivates the chemical reactor by energizing it after adsorption of a certain amount of oxygen, and can efficiently purify nitrogen oxides with low power consumption. The object is to provide a material necessary for low-temperature operation that allows a large amount and a high-speed reaction of a substance to be treated and a system configuration that requires no precious metal.

The present invention for solving the above problems is an electrochemical cell type chemical reactor for performing chemical reaction or energy conversion reaction of a substance to be treated.
1) a combination of the reduction phase ion conducting phase to conduct oxygen ions and by reducing the treated material to produce oxygen ions, or, 2) ion conducting phase, opposite sides of the Re this cathode de及 beauty anode, and A chemical reactor in which a chemical reaction portion is configured by a collective structure of a microelectrochemical cell composed of a basic unit composed of a reduced phase in contact with an ion conductive phase , or both of them,
An oxidation phase connected to the working electrode layer, the reduction phase, and the ion conduction phase is formed in this order from the flow side of the material to be treated in the aggregate structure of the microelectrochemical cell composed of the above basic units, and the supply electrons by the reduction phase are on the surface The formation of a barrier layer that suppresses reaching the top of the working electrode layer, and the dendritic structure in which the particle size of the crystal particles used in the mixed layer of the reducing phase in contact with the ion conducting phase is reduced to 0.1 microns or less A chemical reactor characterized in that a reaction field is formed at an interface to form a network of ion conductors and electron conductors.
This chemical reactor has the following features: (1) The cathode or reducing phase in which the chemical reaction is performed has a pore size of 0.1 micron or less to prevent oxygen molecules in the material to be treated from easily reacting in the cathode or reducing phase. Having a lowered porous space, (2) the cathode or reducing phase in which the chemical reaction is performed has a structure in which the amount of oxygen deficiency (vacancies) is increased by electrochemical reduction treatment, and (3) the chemical reaction The cathode or the reducing phase that does not contain a space (per reaction layer thickness of 1 micron) whose major axis is 100 nanometers or more with respect to the outside into which the substance to be treated is introduced, and (4) the solid that constitutes the ion conducting phase The use of cerium oxide or bismuth oxide or a compound containing at least one of them as the electrolyte, and (5) the use of a conductive compound, (6) Use platinum and other noble metals as the current path of the chemical reactor by using a compound that can be densely sintered at 1200 ° C. or lower as the solid electrolyte. (7) the material constituting the working electrode layer is composed of ultra-fine mixed powder having an average particle diameter of 1 to 100 nm, and (8) microelectricity composed of the basic unit. It is preferable that the chemical cell assembly structure is arranged in multiple layers, and (9) the microelectrochemical cell assembly structure is arranged in multiple layers in a planar shape in series and / or in parallel. .

Next, the present invention will be described in more detail.
The chemical reactor of the present invention is composed of a combination of an ionic conduction phase and a reduction phase, or an ionic conduction phase, and a reduction phase in contact with a cathode and an anode or an ionic conduction phase facing each other, or both. The chemical reaction part is constituted by an aggregate structure of microelectrochemical cells composed of basic units. As a preferred embodiment of the present invention, a chemical reactor for performing a chemical reaction of a substance to be treated includes a chemical reaction part for advancing the chemical reaction of the substance to be treated, and a barrier for inhibiting ionization of oxygen. It is preferable to consist of a layer.

  The chemical reaction unit that performs a chemical reaction of the target substance preferably has a reduced phase that supplies ions to the elements contained in the target substance to generate ions, and an ion conductive phase that conducts ions from the reduced phase. It is constituted by an aggregate structure of microelectrochemical cells composed of basic units composed of: preferably the reducing phase, the ionic conduction phase, and the oxidation phase for releasing electrons from ions conducted through the ionic conduction phase. It has.

  In the present invention, for example, when the substance to be treated is nitrogen oxide in combustion exhaust gas, the nitrogen oxide is reduced in the reduction phase to generate oxygen ions, and the oxygen ions are conducted in the ion conduction phase. However, the material to be treated in the present invention is not limited to nitrogen oxides, and the chemical reactor of the present invention is, for example, a method of reducing carbon dioxide to produce carbon monoxide, or from methane to hydrogen. The present invention can be applied to a method for generating a mixed gas with carbon oxide or a method for generating hydrogen from water.

The form of the chemical reactor of the present invention is preferably exemplified by, for example, a tubular shape, a flat plate shape, a honeycomb shape, etc. In particular, one through hole having a pair of openings is provided, such as a tubular shape or a honeycomb shape. Alternatively, it is preferable that a plurality of the chemical reaction portions are located in each through hole. As a specific configuration example, it is a multilayer tube having an inner diameter of 1 mm, and a microelectrochemical cell layer (layer thickness: 100-300) comprising an oxidation catalyst layer (porous layer thickness of 100 microns), a reducing phase and an ion conducting phase from the inside. Unit structure composed of the outermost oxide layer (layer thickness: 50 microns) connected to this is vertically and horizontally arranged at intervals of 0.5 mm in a thermal shock-resistant ceramic porous body (such as cordierite). The whole structure arranged in one direction along the gas flow path is illustrated. Or it is a flat form, and it is similarly preferable that it is a form which has a reaction area as large as possible because a chemical reaction part is located in the surface. Specific examples of the structure include an oxidation catalyst layer (porous layer thickness of 100 microns), a microelectrochemical cell layer (layer thickness of 100 to 300 microns) composed of a reduction phase and an ion conduction phase , and an oxide layer connected thereto. The multilayer flat unit structures arranged from the gas inflow side in the order of (layer thickness 50 microns) are alternately arranged face-to-face, or alternately by the above-mentioned multilayer unit structure bent like a corrugated board structure. An example of the entire structure configured by arranging the sides is illustrated.

  In the present invention, the reducing phase is preferably porous and selectively adsorbs a substance to be reacted. In the reduction phase, an electron is supplied to an element contained in the material to be treated to generate ions, and the generated ions are transmitted to the ion conduction phase, and therefore, preferably include a conductive material. Further, in order to promote the transfer of electrons and ions, it is more preferably composed of a mixed conductive material having both electron conductivity and ion conductivity characteristics, or a mixture of an electron conductive material and an ion conductive material. . The reducing phase may have a structure in which at least two phases of these substances are laminated.

  The conductive substance and ionic conductive substance used as the reducing phase are not particularly limited. Examples of the conductive substance include noble metals such as platinum and palladium, nickel oxide, cobalt oxide, copper oxide, Metal oxides such as lanthanum manganite, lanthanum cobaltite and lanthanum chromite are used. Barium-containing oxides or zeolites that selectively adsorb the material to be treated are also used as the reducing phase. It is preferable to use at least one kind of the substance as a mixture with at least one kind of ion conductive substance. Examples of the ion conductive substance include zirconia stabilized with yttria or scandium oxide, ceria stabilized with gadolinium oxide or samarium oxide, lanthanum gallate, and the like. It is also preferable that the reducing phase has a structure in which at least two phases of the above substances are laminated. Addition of a noble metal such as platinum is preferable if the improvement of performance is given the highest priority. However, from the viewpoint of practicality such as manufacturing cost, the reduction phase is more preferably a conductive substance phase (metal) other than a noble metal such as platinum. Or a mixture of ceramics or a mixture of both) and a mixed phase of nickel oxide and zirconia stabilized with yttria or scandium oxide.

  In the present invention, bismuth oxide is used for the ion conductive phase. Bismuth oxide-based ionic conductors exhibit the highest level of conductivity among ceramic materials. Replacing them partially or as a whole greatly reduces the operating voltage of chemical reactors and thus power consumption. Contribute.

  The ion conductive phase is made of a solid electrolyte having ion conductivity, and preferably made of a solid electrolyte having oxygen ion conductivity. Examples of the solid electrolyte having oxygen ion conductivity include, but are not particularly limited to, zirconia stabilized with yttria or scandium oxide, ceria stabilized with gadolinium oxide or samarium oxide, and lanthanum gallate. Preferably, zirconia stabilized with yttria or scandium oxide having high conductivity and strength and excellent long-term stability is used. Alternatively, a ceria-based solid electrolyte is also preferably used for an application that can achieve its intended purpose by operating for a relatively short time. More preferably, by using the above-described bismuth oxide ion conductor, ion conductivity is greatly improved, and sufficient ion conduction characteristics can be obtained even at an operating temperature of 400 ° C. or lower, preferably 300 to 400 ° C. can get. Since the sintering temperature, melting temperature, and ionic conductivity change depending on the type and amount of the additive to bismuth oxide, the composition ratio is determined by the combination with the material constituting the other part. In addition, it is necessary to consider the influence on the conductivity due to the chemical reaction between the bismuth-based oxide and other materials. In the present invention, an electrolyte material made of ceria, bismuth, and lanthanum gallate that operates at a low temperature is preferably used.

  In the present invention, the oxidation phase contains a conductive substance in order to emit electrons from ions in the ion conduction phase. In order to promote the transmission of electrons and ions, it is preferable that the material is composed of a mixed conductive material having both electron conductivity and ion conductivity properties, or a mixture of an electron conductive material and an ion conductive material. The conductive substance and ion conductive substance used as the oxidation phase are not particularly limited. Examples of the conductive substance include noble metals such as platinum and palladium, nickel oxide, cobalt oxide, copper oxide, and lanthanum. Metal oxides such as manganite, lanthanum cobaltite and lanthanum chromite are used. Examples of the ion conductive material include zirconia stabilized with yttria or scandium oxide, ceria stabilized with gadolinium oxide or samarium oxide, and lanthanum gallate.

  In the present invention, the barrier layer is intended to prevent supply of electrons necessary for generating oxygen ions when oxygen molecules are adsorbed on the surface, and the oxygen ions are electrically conductive in the chemical reaction part. It is installed for the purpose of preventing reoxidation of metal (for example, nickel metal) generated by the reduction reaction of oxide (for example, nickel oxide), and the supply electron from the chemical reaction part, especially the reduction phase, reaches the surface. Material and structure to prevent The material is preferably an ionic conductor, a mixed conductor or an insulator. In the case of a mixed conductor, the electronic conductivity ratio decreases as much as possible because the electronic conduction deterring effect decreases if the electronic conductivity is large. Small is desirable.

  As one of the features of the present invention, in a conventional electrochemical cell type chemical reactor, two electrodes (cathode and anode) sandwiching a solid electrolyte are used as a basic structure for electrically promoting a chemical reaction. In the present invention, the above structure that forms an electric circuit as a whole is not necessarily required, but a local structure that performs a reaction is used. To be activated, only having a combination of an ion conducting phase and a reducing phase is a structural requirement. That is, as an aspect of the microelectrochemical cell, not only a so-called narrow cell structure but also a large effective reaction volume by, for example, composite particles, a dendritic network, a fractal structure, or a combination thereof is exemplified. Further, these structures will be described in detail. In the present invention, it is preferable that the aggregate structure of the microelectrochemical cells composed of the above basic units is arranged in a multilayer in series and / or in parallel in a planar shape. As an example. Thereby, it is possible to increase the reaction region while the basic unit keeps its essential structural factor.

  FIG. 1 shows an example of the structural feature. In the present invention, the chemical reaction part is provided with an ion conductive phase and a cathode and an anode opposed to the ion conductive phase, or the ion conductive phase, which are necessary for the substance to be treated to react in order to increase the efficiency. It is composed of an aggregate structure of microelectrochemical cells composed of basic units composed of a reducing phase in contact with them or both of them, and it is possible to increase the surface area that reacts with the substance to be treated.

  As the structure forming means, the particle size of the crystal particles used in the mixed layer of the ion conduction phase-electron conduction phase in the chemical reaction part is the same as the oxygen molecule in the material to be treated easily reacts in the cathode or the reduction phase. In order to prevent this, the material to be treated passes through a porous space that has been lowered from about 1 micron to about 0.1 micron or less. The control means is not limited to these.

Further, in the present invention, in order to increase the reaction surface of the cathode or the reduction phase for performing the chemical reaction, the oxygen molecule in the material to be treated is easily added to the cathode or the reduction phase simultaneously with the electrochemical reduction treatment. A predetermined spatial structure is provided to prevent reaction. In this case, the electrochemical reduction treatment is preferably performed within an applied voltage range of 1.0 V to 3.0 V (per reaction surface area of 1 cm ² ), thereby increasing the amount of oxygen deficiency (vacancies) due to the local electric field. In order to prevent oxygen molecules in the material to be treated from easily reacting in the cathode or the reducing phase, the cathode or the reducing phase is connected to the outside where the material to be treated is introduced. It is preferable not to include a space having a major axis of 100 nanometers or more (per reaction layer thickness of 1 micron). As a result, the reaction activity can be maintained even if the ion conductivity is lowered at a low temperature.

  With such a structure, two or more types of atomic molecules or compounds may be simultaneously or shortly used in a chemical reaction such as reductive decomposition of nitrogen oxides, which is conventionally possible only at the same reaction site (reaction active site). Providing different reaction sites for reactions that occur in parallel and competing with time and increasing the reaction volume, thereby increasing the selectivity of the reaction and, as a result, dramatically improving the reaction efficiency. It is.

  As such a structure, a combination of an ion conduction phase and an electron conduction phase, a mixed conduction phase, or a combination of this with an ion conduction phase and an electron conduction phase are possible. When the substance to be treated is a nitrogen oxide, a transition metal phase such as nickel is more preferable as the reduction phase because it can selectively adsorb covalently bonded molecules.

  In order to reduce the material cost required for practical use of such a reactor, it is important to avoid the use of noble metals such as platinum as much as possible. The need to use platinum in conventional chemical reactors may be a stable material that can maintain high electrical conductivity, even after high temperature manufacturing processes, in addition to the inherently high electronic conductivity characteristics.

Therefore, it is an extremely important requirement to newly develop and use a material capable of performing the manufacturing process of the chemical reactor of the present invention without using platinum. In the present invention, for example, bismuth oxide containing barium (BaO / Y ₂ O ₃ / Bi ₂ O ₃ , BaO / CeO ₂ / ZrO ₂ / Bi ₂ O ₃ ) or the like is used as the solid electrolyte (ion conductive phase). By doing so, the process temperature can be reduced from the conventional 1450 ° C. to 1200 ° C. As a result, it is possible to introduce a dense layer into the chemical reaction section without using platinum and other noble metals as the current path of the chemical reactor, thereby realizing a highly efficient reaction.

  According to the present invention, (1) it is possible to provide a chemical reactor suitable for purifying a large flow rate object such as automobile exhaust gas, and (2) low temperature operation with an increased reaction surface area in the chemical reaction section. It is possible to provide a chemical reactor. (3) With the chemical reactor of the present invention, for example, nitrogen oxide can be purified with high efficiency by low power consumption. (4) A large amount of exhaust gas is treated. It is possible to provide a basic unit of a new chemical reaction part suitable for the above and an arrangement structure thereof.

EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.
FIG. 1 is an example of a typical internal structure in a configuration example of a chemical reactor according to an embodiment of the present invention. Hereinafter, the case where the material to be treated is nitrogen oxide will be specifically described.

As the substrate of the ion conductive phase that becomes the base constituting the chemical reactor, zirconia stabilized with densely sintered yttria was used, and the shape thereof was a disk shape having a diameter of 20 mm and a thickness of 0.5 mm. . For the reduction phase, a mixed layer of metallic nickel and bismuth oxide was used. As the working electrode layer, a film made of a mixture of nickel oxide, zirconia, ceria, and barium-added bismuth oxide was used. A reduced phase was formed by screen-printing a mixture of metallic nickel and bismuth oxide on one side of the ion conductive phase so as to have an area of about 1.8 cm ² , followed by heat treatment at 1100 ° C. A mixed film of nickel oxide, ceria and barium-added bismuth oxide was screen-printed on the metallic nickel and bismuth oxide film so as to have the same area, and then heat treated at 1100 ° C. to form a working electrode layer. The mixing ratio of nickel oxide, zirconia, perovskite oxide and ceria was 5: 1: 2: 2 in molar ratio. A film made of lanthanum strontium manganite and its compound is screen-printed on the other surface of the ion-conductive phase forming the reduced phase so as to have an area of about 1.8 cm ² , followed by heat treatment at 1200 ° C. Formed. Ultrafine alumina was used for the barrier layer, and was formed on the working electrode layer to a thickness of about 3 microns by screen printing and heat treatment at 1100 ° C. Furthermore, the temperature was raised to 650 ° C. while a current of 1.0 V-15 mA was applied between the cathode and the anode, and after 3 hours, the current supply was stopped and the mixture was gradually cooled.

Next, the basic unit constituting the chemical reaction part of the chemical reactor and the combination structure thereof will be specifically described. As described above, this chemical reactor is composed of an ion conduction phase and a reduction phase, a working electrode layer, an oxidation phase, a barrier layer, a cathode and an anode. The chemical reaction part was constituted by an aggregate structure of a microelectrochemical cell composed of an ion conductive phase, and a basic unit composed of a cathode and an anode opposed to each other and a reducing phase in contact with the ion conductive phase. Further, this chemical reaction section, the ion Den Shirubesho - lowering the particle size of the mixed layer in the crystal particles used in the reduction phase below 0.1 microns With dendritic structure, the number 10nm dendritic structure A reaction field was formed at the interface. By their constituted the network of the ion Den conductors and electronic conductors.

  Next, a method for treating nitrogen oxides by the chemical reactor of the present invention thus formed will be described. A chemical reactor was placed in the gas to be treated, platinum wires were fixed as lead wires to the reduction phase and the oxidation phase, connected to a DC power source, and a DC voltage was applied to pass a current. As the gas to be treated, a model combustion exhaust gas of 1000 ppm nitric oxide, 2% oxygen and helium balance was flowed at a flow rate of 50 ml / min. The nitrogen oxide concentration in the gas to be treated before and after flowing into the chemical reactor was measured with a chemiluminescent NOx meter, and the nitrogen and oxygen concentrations were measured with gas chromatography. From the reduction amount of nitrogen oxides, the purification rate of nitrogen oxides was determined, and the current density and power consumption when the purification rate was 50% were measured.

That is, at the start of measurement, the chemical reactor was heated to a reaction temperature of 350 ° C., and the chemical reaction part was energized. At this time, the purification rate of nitrogen oxides was improved as the amount of current increased, and the nitrogen oxides decreased to about 70% when the current density was 20 mA / cm ² and the power consumption was 25 mW / cm ² .

  The chemical reactor was further deenergized 30 minutes after the start of energization, and when the measurement of the decomposition rate of nitrogen oxide was continued as it was, the decomposition rate of nitrogen oxide was about 10% immediately after the energization was stopped. Although it decreased, it showed a gradual decrease thereafter, and it was possible to continue the reaction with a decrease of 3% or less even in continuous measurement for about 100 hours. It was confirmed by measurement for a total of 400 hours that the operation could be continued for a long time without deteriorating the decomposition performance of nitrogen oxides by repeating this operation.

  A chemical reactor was prepared using the same materials and procedures as in Example 1. All of zirconia, nickel oxide, bismuth oxide, and ceria constituting the working electrode were preliminarily pulverized and mixed to obtain an ultrafine particle mixed powder having an average particle diameter of about 80 nm as a raw material used for screen printing. Furthermore, in the structure formation process by the electrochemical reaction of the working electrode layer, in order to prevent excessive void formation and performance degradation due to application of an excessive electric field, the current-carrying condition between the cathode and the anode is relaxed to 0.8 V-8 mA, The temperature was raised to 650 ° C. and maintained for 10 hours, and then the energization was stopped and gradually cooled. As a result, the reaction effective volume in the working electrode layer was estimated from the result of electron microscopic observation of the tissue, and an increase of about 5 times compared with the case of Example 1 was recognized.

The chemical reactor thus manufactured was examined for nitrogen oxide purification performance in the same manner as in Example 1. Nitrogen oxide purification rate is 20 mW / cm ² for 70% purification at high temperature continuous operation (560 ° C.), intermittent energization at low temperature (350 ° C., 1.5 V-40 mA energization every 1 hour / 20 hours ) Average power consumption at 40% purification was about 3 mW / h.

  As described in detail above, the present invention relates to an electrochemical cell type chemical reactor, and according to the present invention, even when oxygen that interferes with the chemical reaction of the substance to be treated is excessively present, It is possible to provide a chemical reactor capable of processing a material to be processed with high efficiency and low power consumption. In addition, the present invention can provide a chemical reactor suitable for purifying a large flow rate object to be processed such as automobile exhaust gas. A chemical reactor capable of operating at a low temperature with an increased reaction surface area in the chemical reaction section can be provided. The chemical reactor of the present invention can purify nitrogen oxide with high efficiency, for example, with low power consumption. It is possible to provide a basic unit of a new chemical reaction part suitable for treating a large flow rate of exhaust gas and its arrangement structure.

It is a schematic diagram which shows an example of a structure and internal structure of the chemical reactor of this invention.

Claims (10)

In an electrochemical cell type chemical reactor for performing chemical reaction or energy conversion reaction of the material to be treated,
1) a combination of the reduction phase ion conducting phase to conduct oxygen ions and by reducing the treated material to produce oxygen ions, or, 2) ion conducting phase, opposite sides of the Re this cathode de及 beauty anode, and A chemical reactor in which a chemical reaction portion is configured by a collective structure of a microelectrochemical cell composed of a basic unit composed of a reduced phase in contact with an ion conductive phase , or both of them,
An oxidation phase connected to the working electrode layer, the reduction phase, and the ion conduction phase is formed in this order from the flow side of the substance to be processed in the aggregate structure of the microelectrochemical cell composed of the above basic units, and the supply electrons by the reduction phase are formed on the surface. Forming a barrier layer on top of the working electrode layer to prevent it from reaching,
A reaction field is formed at the interface of the dendritic structure in which the particle size of the crystal particles used in the mixed layer of the reducing phase in contact with the ionic conduction phase is reduced to 0.1 microns or less, and a network of ionic and electronic conductors is formed. What
A chemical reactor characterized by   The cathode or reducing phase for performing a chemical reaction has a porous space lowered to a pore size of 0.1 micron or less to prevent oxygen molecules in the material to be treated from easily reacting in the cathode or the reducing phase. The chemical reactor according to 1.   The chemical reactor according to claim 2, wherein the cathode or the reducing phase that performs the chemical reaction has a structure in which the amount of oxygen deficiency (vacancies) by the electrochemical reduction treatment is increased.   3. The chemical reactor according to claim 2, wherein the cathode or the reducing phase for performing the chemical reaction does not include a space (per reaction layer thickness of 1 micron) having a major axis of 100 nanometers or more with respect to the outside into which the substance to be treated is introduced.   The chemical reactor according to claim 1, wherein a cerium oxide or a bismuth oxide or a compound containing at least one of them is used as the solid electrolyte constituting the ion conductive phase.   The chemical reactor according to claim 1, wherein platinum is not used in any part of the chemical reactor by using a conductive compound.   The basic unit is formed according to claim 1, wherein a compound that can be densely sintered at 1200 ° C or less is used as a solid electrolyte, and platinum and other noble metals are not used as a current path of a chemical reactor. Chemical reactor.   The chemical reactor according to claim 1, wherein the material constituting the working electrode layer is an ultrafine particle mixed powder having an average particle diameter of 1 to 100 nm.   The chemical reactor according to claim 1, wherein the aggregate structure of the microelectrochemical cells composed of the basic units is arranged in multiple layers.   The chemical reactor according to claim 1, wherein the aggregate structure of the microelectrochemical cells is arranged in multiple layers in a planar shape in series and / or in parallel.