Method for Producing Coating Composition, Yttria-Stabilized Zirconia Layer, Electrochemical Element, Electrochemical Module, Electrochemical Device, Energy System, Solid Oxide Fuel Cell, and Solid Oxide Electrolysis Cell
20230352698 · 2023-11-02
Inventors
Cpc classification
International classification
Abstract
-- A coating composition enables film formation at low cost with a simple method by using a zirconium alkoxide and an yttrium compound as starting raw materials, and enables a dense yttria-stabilized zirconia layer to be obtained, The coating composition containing the zirconium alkoxide, the yttrium compound, a chelate compound, a catalyst, water, and an organic solvent is obtained. The coating composition may also contain yttria-stabilized zirconia fine particles
Claims
1. A method for producing a coating composition comprising: mixing a composition containing a zirconium alkoxide, an yttrium compound, a chelate compound, a catalyst, water, and an organic solvent to produce a coating composition.
2. The method for producing a coating composition according to claim 1, wherein the coating composition contains yttria-stabilized zirconia fine particles.
3. The method for producing a coating composition according to claim 2, wherein a content of the yttria-stabilized zirconia fine particles is 1% to 10% by mass with respect to the zirconium alkoxide.
4. The method for producing a coating composition according to claim 2, wherein an average particle size of the yttria-stabilized zirconia fine particles is 0.1 to 2 .Math.m.
5. The method for producing a coating composition according to claim 1, wherein in the coating composition, a content of the zirconium alkoxide is 10% to 30% by mass, a content of the yttrium compound is 1% to 10% by mass, a content of the chelate compound is 5% to 20% by mass, a content of the catalyst is 0.1% to 2% by mass, a content of the water is 0.1% to 2% by mass, and a content of the organic solvent is a remainder.
6. The method for producing a coating composition according to claim 1, wherein the zirconium alkoxide is any one or more of zirconium (IV) methoxide, zirconium (IV) ethoxide, zirconium (IV) n-propoxide, zirconium (IV) i-propoxide, zirconium (IV) n-butoxide, zirconium (IV) i-butoxide, zirconium (IV) sec-butoxide, or zirconium (IV) t-butoxide.
7. The method for producing the coating composition according to claim 1, wherein the yttrium compound is any one or more of yttrium nitrate, yttrium chloride, yttrium sulfate, yttrium phosphate, yttrium acetate, yttrium carbonate, yttrium (III) ethoxide, yttrium (III) n-propoxide, or yttrium (III) i-propoxide.
8. The method for producing the coating composition according to claim 1, wherein the chelate compound is General Formula (1), ##STR00006## wherein, in General Formula (1), R1 and R2 are alkyl groups having 1 to 6 carbon atoms, including a fluorinated alkyl group, or monocyclic or bicyclic aryl groups; R1 and R2 are the same or different from each other, and each are an alkyl group having 1 to 6 carbon atoms or a monocyclic or bicyclic aryl group, and R1 and R2 may be bonded to each other to form a cyclic alkyl group.
9. The method for producing the coating composition according to claim 1, wherein the chelate compound is any one or more of 2,4-pentanedione, 2,4-hexanedione, 3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 1-phenyl-1,3-butanedione, 1,3-diphenyl-1,3-propanedione, 1,1,1-trifluoro-2,4-pentanedione, 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, or 1,3-cyclohexanedione.
10. The method for producing the coating composition according to claim 1, wherein the catalyst is any one or more of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid, or acetic acid.
11. The method for producing the coating composition according to claim 1, wherein the organic solvent is any one or more of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, or 2-methyl-2-propanol.
12. The method for producing the coating composition according to claim 1, wherein the organic solvent is an alcohol having a smaller number of carbon atoms than an alcohol corresponding to an alkoxide of the zirconium alkoxide.
13. An yttria-stabilized zirconia layer obtained by curing the coating composition that is produced by the method for producing the coating composition according to claim 1.
14. An electrochemical element comprising the yttria-stabilized zirconia layer according to claim 13.
15. The electrochemical element according to claim 14, wherein the electrochemical element includes a metal support.
16. An electrochemical module comprising a plurality of the electrochemical elements according to claim 14, which are disposed in a state of being assembled.
17. An electrochemical device comprising: at least one electrochemical element according to claim 14 ; and a fuel converter that supplies a gas containing a reduction gas to the at least one electrochemical element, or a fuel converter for converting a gas containing a reduction gas generated from the at least one electrochemical element .
18. An electrochemical device comprising: at least one electrochemical element according to claim 14 ; and an electric power converter that extracts electric power from the at least one electrochemical element, or an electric power converter that supplies electric power to the at least one electrochemical element.
19. An energy system comprising: the electrochemical device according to claim 17; and an exhaust heat utilization section that reuses heat discharged from the electrochemical device.
20. A solid oxide fuel cell comprising the electrochemical element according to claim 14, wherein the solid oxide fuel cell causes a power generation reaction in the electrochemical element.
21. A solid oxide electrolysis cell comprising the electrochemical element according to claim 14, wherein the solid oxide electrolysis cell causes an electrolytic reaction in the electrochemical element.
Description
BRIEF DESCRIPTION OF DRAWINGS
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DESCRIPTION OF THE INVENTION
[0086] Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited thereto.
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[0088] As described above, the coating composition b2 produced by a method for producing a coating composition according to the present invention contains a zirconium alkoxide o, an yttrium compound p, a chelate compound q, a catalyst r, a water s, and an organic solvent t, which are in a mixed state. Furthermore, in a case of containing the yttria-stabilized zirconia fine particles Pa, the yttria-stabilized zirconia fine particles Pa are added. As illustrated in
[0089] Here, the zirconium alkoxide o is a starting raw material of the yttria-stabilized zirconia coating layer, and examples thereof include zirconium (IV) methoxide, zirconium (IV) ethoxide, zirconium (IV) n-propoxide, zirconium (IV) i-propoxide, zirconium (IV) n-butoxide, zirconium (IV) i-butoxide, zirconium (IV) sec-butoxide, or zirconium (IV) t-butoxide.
[0090] A content of this zirconium alkoxide o in the composition b2 is preferably 10% to 30% by mass.
[0091] In Examples and Comparative Examples described below, an example in which zirconium (IV) n-propoxide and zirconium (IV) n-butoxide are used is illustrated.
[0092] Examples of the yttrium compound p include yttrium nitrate, yttrium chloride, yttrium acetate, yttrium carbonate, yttrium (III) ethoxide, yttrium (III) n-propoxide, yttrium (III) i-propoxide, and the like.
[0093] A content of the yttrium compound p in the coating composition b2 is preferably 1% to 10% by mass.
[0094] In the following Examples and Comparative Examples, an example in which yttrium nitrate is used is illustrated.
[0095] Examples of the chelate compound q includes 2,4-pentanedione, 2,4-hexanedione, 3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 1-phenyl-1,3-butanedione, 1,3-diphenyl-1,3-propanedione, 1,1,1-trifluoro-2,4-pentanedione, 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, 1,3-cyclohexanedione, and the like.
[0096] The amount of the chelate compound q added is preferably about 0.5 to 3 mol with respect to 1 mol of zirconium alkoxide. A content of the chelate compound q in the coating composition b2 is preferably 5% to 20% by mass.
[0097] In the following Examples and Comparative Examples, an example in which 2,4-pentanedione, 3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, and 2,2,6,6-tetramethyl-3,5-heptanedione are used is illustrated.
[0098] Hydrochloric acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, and the like can be used as the catalyst r. A content of the catalyst r in the coating composition b2 is preferably 0.1% to 2% by mass. In the following Examples and Comparative Examples, an example in which nitric acid is used is illustrated.
[0099] Since the water s is also used for hydrolysis of the zirconium alkoxide o, it is difficult to achieve the purpose of a hydrolysis reaction proceeding with unique to the composition in a case of less than 0.25 mol, and even in a case of more than 1.0 mol, a further effect cannot be obtained. From the viewpoint of coatability and ease of handling of the coating composition b2, a content of the water s in the coating composition b2 is preferably within a range of about 0.1% to 2% by mass.
[0100] Examples of the organic solvent t include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, and 2-methyl-2-propanol. The organic solvent t is the remaining amount of other components.
[0101] In Examples and Comparative Examples described below, an example in which ethanol, 1-propanol, 2-propanol, and 1-butanol are used is illustrated.
[0102] As the yttria-stabilized zirconia fine particles Pa, a commercially available powder product can be used. A content in the coating composition b2 is preferably 1% to 10% by mass with respect to the zirconium alkoxide o. An average particle size of the yttria-stabilized zirconia fine particles Pa is preferably 0.1 to 2 .Math.m. From the viewpoint of coatability and ease of handling of the coating composition b2, a content of the yttria-stabilized zirconia fine particles Pa in the coating composition b2 is preferably within a range of about 0.1% to 1% by mass.
Examples and Comparative Examples
[0103] Examples 1 to 11 and Comparative Examples 1 to 4 illustrated below are examples in which, as illustrated in
[0104] As described later, the yttria-stabilized zirconia layer can be an electrolyte layer 4, but the gadolinium-doped ceria b1 is assumed as an interlayer 3 provided between the electrolyte layer 4 and an electrode layer 2 for forming the electrochemical element E (see paragraphs [124] to [134], and
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1. Example 1
[0108] 5.65 g of zirconium (IV) n-propoxide, 1.65 g of yttrium nitrate hexahydrate, 3.45 g of 2,4-pentanedione, 0.27 g of 60% nitric acid, 0.12 g of water, and 38.85 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0109] Separately, the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 1.5 .Math.m.
[0110] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
[0111] Hereinafter,
2. Example 2
[0112] 5.79 g of zirconium (IV) n-propoxide, 1.69 g of yttrium nitrate hexahydrate, 2.27 g of 3,5-heptanedione, 0.28 g of 60% nitric acid, 0.13 g of water, and 39.84 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0113] Separately, the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 1.5 .Math.m. In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
3. Example 3
[0114] 5.74 g of zirconium (IV) n-propoxide, 1.68 g of yttrium nitrate hexahydrate, 2.74 g of 2,6-dimethyl-3,5-heptanedione, 0.28 g of 60% nitric acid, 0.12 g of water, and 39.45 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0115] Separately, the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 1.4 .Math.m.
[0116] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
4. Example 4
[0117] 5.68 g of zirconium (IV) n-propoxide, 1.66 g of yttrium nitrate hexahydrate, 3.20 g of 2,2,6,6-tetramethyl-3,5-heptanedione, 0.27 g of 60% nitric acid, 0.12 g of water, and 39.07 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0118] Separately, the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 1.2 .Math.m.
[0119] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
5. Example 5
[0120] 6.90 g of zirconium (IV) n-propoxide, 2.02 g of yttrium nitrate hexahydrate, 4.22 g of 2,4-pentanedione, 0.33 g of 60% nitric acid, 0.15 g of water, and 36.39 g of ethanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, ethanol as a solvent is an alcohol corresponds to an alcohol having a smaller number of carbon atoms than the alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0121] Separately, the coating composition was applied to a test piece B as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 3.6 .Math.m.
[0122] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
6. Example 6
[0123] 5.51 g of zirconium (IV) n-butoxide, 1.38 g of yttrium nitrate hexahydrate, 2.88 g of 2,4-pentanedione, 0.23 g of 60% nitric acid, 0.10 g of water, and 39.91 g of 1-butanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 1-butanol as a solvent is the same as an alcohol (1-butanol) corresponding to the alkoxide of the zirconium alkoxide.
[0124] Separately, the coating composition was applied to a test piece B as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 1.3 .Math.m.
[0125] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
7. Example 7
[0126] 6.49 g of zirconium (IV) n-butoxide, 1.62 g of yttrium nitrate hexahydrate, 3.39 g of 2,4-pentanedione, 0.27 g of 60% nitric acid, 0.12 g of water, and 36.49 g of 2-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 2-propanol as a solvent is an alcohol corresponds to an alcohol having a smaller number of carbon atoms than the alcohol (1-butanol) corresponding to the alkoxide of the zirconium alkoxide.
[0127] Separately, the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 3.6 .Math.m.
[0128] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
8. Example 8
[0129] 6.49 g of zirconium (IV) n-butoxide, 1.62 g of yttrium nitrate hexahydrate, 3.39 g of 2,4-pentanedione, 0.27 g of 60% nitric acid, 0.12 g of water, and 36.49 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 1-propanol as a solvent is an alcohol corresponds to an alcohol having a smaller number of carbon atoms than the alcohol (1-butanol) corresponding to the alkoxide of the zirconium alkoxide.
[0130] Separately, the coating composition was applied to a test piece B as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 3.6 .Math.m.
[0131] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
9. Example 9
[0132] 7.89 g of zirconium (IV) n-butoxide, 1.97 g of yttrium nitrate hexahydrate, 4.12 g of 2,4-pentanedione, 0.32 g of 60% nitric acid, 0.15 g of water, and 35.55 g of ethanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, ethanol as a solvent is an alcohol corresponds to an alcohol having a smaller number of carbon atoms than the alcohol (1-butanol) corresponding to the alkoxide of the zirconium alkoxide.
[0133] Separately, the coating composition was applied to a test piece B as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 3.6 .Math.m.
[0134] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
10. Example 10
[0135] 5 g of yttria-stabilized zirconia (8YSZ) fine particles having an average particle size of 0.2 .Math.m was weighed in a 200 ml resin container, and 95 g of 1-propanol was added. The mixture was stirred for 2 hours by using a vibration stirrer to prepare a 1-propanol dispersion of 8YSZ fine particles.
[0136] 5.65 g of zirconium (IV) n-propoxide, 1.65 g of yttrium nitrate hexahydrate, 3.45 g of 2,4-pentanedione, 0.27 g of 60% nitric acid, 0.12 g of water, 5.65 g of a 1-propanol dispersion of the yttria-stabilized zirconia (8YSZ) fine particles (5% by weight of zirconium (IV) n-propoxide), and 30.78 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0137] Separately, the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 2.1 .Math.m.
[0138] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
11. Example 11
[0139] 5 g of yttria-stabilized zirconia (8YSZ) fine particles having an average particle size of 0.2 .Math.m was weighed in a 200 ml resin container, and 95 g of 1-propanol was added. The mixture was stirred for 2 hours by using a vibration stirrer to prepare a 1-propanol dispersion of 8YSZ fine particles.
[0140] 5.79 g of zirconium (IV) n-propoxide, 1.69 g of yttrium nitrate hexahydrate, 2.27 g of 3,5-heptanedione, 0.28 g of 60% nitric acid, 0.13 g of water, 5.79 g of a 1-propanol dispersion of the yttria-stabilized zirconia (8YSZ) fine particles (5% by weight of zirconium (IV) n-propoxide), and 31.57 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0141] Separately, the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes to prepare a coating film. Furthermore, the coating film was held at 1000° C. for 60 minutes to prepare a coating film. There was no damage such as cracking or peeling of the coating film, and a film thickness was 2.0 .Math.m.
[0142] In a case where the coating film was analyzed by X-ray diffraction, clear peaks of yttria-stabilized zirconia were found at 30, 35, 50, 60, 62, and 74 of 2θ as illustrated in
8. Comparative Example 1 (Without Chelate Compound)
[0143] 6.07 g of zirconium (IV) n-propoxide, 1.77 g of yttrium nitrate hexahydrate, 0.29 g of 60% nitric acid, 0.13 g of water, and 41.74 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. No chelate agent was used as the chelate compound. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0144] Separately, in a case where the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes, cracks occurred on the entire surface of the coating film, and peeling was observed. Since peeling was observed on the coating film at the time of drying at 80° C., calcinating (holding) at 1000° C. was not carried out.
[0145] In Comparative Example 1, it is considered that hydrolysis of zirconium (IV) propoxide and a polycondensation reaction proceeded rapidly since the chelate compound was not added, so that cracks occurred on the front surface of the coating film, resulting in peeling off.
9. Comparative Example 2 (Without Nitric Acid)
[0146] 5.68 g of zirconium (IV) n-propoxide, 1.66 g of yttrium nitrate hexahydrate, 3.47 g of 2,4-pentanedione, 0.12 g of water, and 39.07 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. The 60% nitric acid was not used as a catalyst. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0147] Separately, in a case where the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes, cracks occurred on an end portion (outer circumferential portion) of the coating film, and peeling was observed. Since peeling was observed on the coating film at the time of drying at 80° C., calcinating at 1000° C. was not carried out.
[0148] In Comparative Example 2, it is considered that hydrolysis of zirconium (IV) n-propoxide and a polycondensation reaction proceeded ununiformly since the nitric acid as the catalyst was not added, so that cracks occurred on the end portion of the coating film, resulting in peeling off.
10. Comparative Example 3 (Without Nitric Acid and Water)
[0149] 5.69 g of zirconium (IV) n-propoxide, 1.66 g of yttrium nitrate hexahydrate, 3.48 g of 2,4-pentanedione, and 39.16 g of 1-propanol were charged into a 150 ml glass container and were blended, and the mixture was stirred by using a magnetic stirrer for 3 hours to prepare 50 g of a coating composition. The 60% nitric acid and water were not used as a catalyst. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0150] Separately, in a case where the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes, cracks occurred on an end portion (outer circumferential portion) of the coating film, and peeling was observed similar to Comparative Example 2. Since peeling was observed on the coating film at the time of drying at 80° C., calcinating at 1000° C. was not carried out.
[0151] In Comparative Example 3, it is considered that hydrolysis of zirconium (IV) n-propoxide was insufficient, and a polycondensation reaction proceeded partially since the nitric acid as the catalyst and water were not added, so that cracks occurred on the end portion of the coating film, resulting in peeling off.
[0152] 11. Comparative Example 4 (Reproduction of Example described in JP-A-H7-235317)
[0153] An equal amount of a 0.5 M-1-propanol solution of zirconium (IV) n-propoxide and a 0.087 M-1-propanol solution of yttrium nitrate hexahydrate were mixed, and a 0.5 M-1-propanol solution of 2,4-pentanedione was then added in a 150 ml glass container so that zirconium was contained in a ratio of 2 (molar ratio) to 2,4-pentanedione to prepare 50 g of a coating composition. In this example, 1-propanol as a solvent is the same as an alcohol (1-propanol) corresponding to the alkoxide of the zirconium alkoxide.
[0154] Separately, in a case where the coating composition was applied to the test piece as a subject by using an air spray and heat-treated at 80° C. for 30 minutes, the entire surface of the coating film was scabrous and had rough appearance, and the coating film was easily peeled off by a simple touch with a finger. Since peeling was observed on the coating film at the time of drying at 80° C., calcinating at 1000° C. was not carried out.
[0155] In Comparative Example 4, it is considered that hydrolysis of zirconium (IV) n-propoxide was insufficient, and a polycondensation reaction proceeded partially since the nitric acid as the catalyst and water were not added, so that the entire surface of the coating film was scabrous and had rough appearance, and the coating film was easily peeled off.
[0156] Examples of combinations for obtaining the suitable coating composition b2 and the yttria-stabilized zirconia coating film by using the zirconium alkoxide o, the yttrium compound p, the chelate compound q, the catalyst r, the water s, and the organic solvent t include the following combinations in addition to the combinations described in Examples 1 to 11. However, the present invention is not limited to these combinations. The following combinations can be selected regardless of the addition and content of the yttria-stabilized zirconia fine particles Pa. [0157] a) Zirconium (IV) n-propoxide, yttrium (III) i-propoxide, 2,4-pentanedione, nitric acid, water, and 1-propanol [0158] a) Zirconium (IV) n-propoxide, yttrium (III) i-propoxide, 3,5-heptanedione, nitric acid, water, and 1-propanol [0159] c) Zirconium (IV) i-propoxide, yttrium (III) i-propoxide, 2,4-pentanedione, nitric acid, water, and 2-propanol [0160] d) Zirconium (IV) i-propoxide, yttrium (III) i-propoxide, 3,5-heptanedione, nitric acid, water, and 2-propanol [0161] e) Zirconium (IV) n-butoxide, yttrium acetate, 2,4-pentanedione, acetic acid, water, and 1-butanol [0162] f) Zirconium (IV) n-butoxide, yttrium acetate, 3,5-heptanedione, acetic acid, water, and 1-butanol [0163] g) Zirconium (IV) n-propoxide, yttrium chloride, 2,4-pentanedione, hydrochloric acid, water, and 1-propanol [0164] h) Zirconium (IV) n-propoxide, yttrium chloride, 3,5-heptanedione, hydrochloric acid, water, and 1-propanol [0165] i) Zirconium (IV) n-propoxide, yttrium sulfate, 2,4-pentanedione, sulfuric acid, water, and 1-propanol [0166] j) Zirconium (IV) n-propoxide o, yttrium sulfate, 3,5-heptanedione, sulfuric acid, water, and 1-propanol
Usage Form of Yttria-Stabilized Zirconia Layer
[0167] Hereinafter, a solid oxide fuel cell that is configured to include an electrochemical element E, this electrochemical element E being formed by using the yttria-stabilized zirconia layer described so far will be described with reference to
[0168] The electrochemical element E is used as, for example, a component of a solid oxide fuel cell that generates power by receiving a fuel gas containing hydrogen and air.
[0169] Hereinafter, in a case of expressing a positional relationship of layers in the description related to the electrochemical element E, a reference layer in the position notation is referred to as the electrolyte layer 4, the counter electrode layer 6 side as viewed from the electrolyte layer 4 is “upper” or an “upper side” (upper side in
Electrochemical Element
[0170] As illustrated in
[0171] As described above, regarding each layer constituting the electrochemical element E, the main elements thereof are the electrolyte layer 4, the electrode layer 2 and the counter electrode layer 6 which are provided to sandwich the electrolyte layer 4, and these three layers can be provided to operate as the electrochemical element E.
Metal Substrate
[0172] The metal substrate 1 serves as a support that supports the electrode layer 2, the interlayer 3, the electrolyte layer 4, and the like to maintain the strength of the electrochemical element E. Although the plate-shaped metal substrate 1 is used as this metal substrate, other shapes such as a box shape, a cylindrical shape, and a disk shape are also can be used as the metal support.
[0173] The metal substrate 1 has the strength as long as the strength enables the electrochemical element E to be sufficiently formed as a support, and for example, it is possible to use the metal substrate 1 having a thickness of about 0.1 mm to 2 mm, preferably about 0.1 mm to 1 mm, and more preferably about 0.1 mm to 0.5 mm.
[0174] The metal substrate 1 has a plurality of through-holes 1a provided to penetrate a front surface and a back surface. Furthermore, for example, the through-hole 1a can be provided in the metal substrate 1 by mechanical, chemical, or optical boring processing. The through-hole 1a has a function of allowing a gas to permeate from the back surface to the front surface of the metal substrate 1. In order to impart gas permeability to the metal substrate 1, it is also possible to use a porous metal. For example, for the metal substrate 1, a sintered metal, a foamed metal, or the like can also be used. As a metal substrate material, a ferrite stainless steel material (an example of Fe—Cr alloy) is used. Furthermore, as illustrated in
[0175] In a case where the Fe—Cr alloy is used as a material for the metal substrate 1, a thermal expansion coefficient of this material is close to that of yttria-stabilized zirconia (YSZ) or gadolinium-doped ceria (GDC, also referred to as CGO) used as a material for the electrode layer 2 or the electrolyte layer 4. As a result, even in a case where a temperature cycle of a low temperature and a high temperature is repeated, the electrochemical element E is less likely to be damaged. Accordingly, an electrochemical element E having excellent long-term durability can be obtained, which is preferable.
Electrode Layer
[0176] As illustrated in
[0177] As a material for the electrode layer 2, for example, a composite material such as NiO—GDC, Ni—GDC, NiO—YSZ, Ni—YSZ, CuO—CeO.sub.2, and Cu—CeO.sub.2 can be used. In these examples, YSZ, GDC, and CeO.sub.2 can be referred to as a composite aggregate. In addition, the electrode layer 2 is preferably formed by a low-temperature calcination method (for example, a wet method using a calcination treatment in a low-temperature range without performing a calcination treatment in a high-temperature range of higher than 1,100° C.), a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. As a result of adopting these processes which can be used in a low-temperature range, a favorable electrode layer 2 can be obtained without using calcination in a high-temperature range of higher than 1,100° C., for example. For the reason, the element interdiffusion between the metal substrate 1 and the electrode layer 2 can be suppressed without damaging the metal substrate 1, and an electrochemical element having excellent durability can be obtained, which is preferable. Furthermore, using the low-temperature calcination method is more preferable because handling of raw materials becomes easy.
[0178] The electrode layer 2 has a plurality of pores inside and on the surface thereof so as to have gas permeability. That is, the electrode layer 2 is formed as a porous layer. The electrode layer 2 is formed, for example, so that the denseness is 30% or greater and less than 80%. As a size of the pore, a size suitable for allowing an electrochemical reaction to smoothly proceed during the reaction can be appropriately selected. Moreover, the denseness is a proportion of a material constituting a layer to a space, can be expressed as (1 -porosity), and is equivalent to a relative density.
Interlayer
[0179] As illustrated in
[0180] The interlayer 3 is preferably formed by a low-temperature calcination method (for example, a wet method using a calcination treatment in a low-temperature range without performing a calcination treatment in a high-temperature range of higher than 1,100° C.), a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. As a result of adopting these film formation processes that can be used in a low-temperature range, the interlayer 3 can be obtained without using calcination in a high-temperature range of higher than 1,100° C., for example. For this reason, the element interdiffusion between the metal substrate 1 and the electrode layer 2 can be prevented without damaging the metal substrate 1, and an electrochemical element E having excellent durability can be achieved. Furthermore, using a low-temperature calcination method is still more preferable since handling of raw materials is easy.
[0181] The interlayer 3 preferably has oxygen ion (oxide ion) conductivity. In addition, the interlayer 3 more preferably has mixed conductivity of an oxygen ion (oxide ion) and an electron. The interlayer 3 having these properties is suitable for application to the electrochemical element E.
Electrolyte Layer
[0182] The electrolyte layer 4 is formed as a thin layer on the interlayer 3 in a state of covering the electrode layer 2 and the interlayer 3, as illustrated in
[0183] In addition, the electrolyte layer 4 is provided in a region which is on the surface of the front side of the metal substrate 1 and is larger than a region where the through-holes 1a are provided. That is, the through-holes 1a are formed inside a region of the metal substrate 1 where the electrolyte layer 4 is formed.
[0184] Furthermore, gas leakage from the electrode layer 2 and the interlayer 3 can be prevented at the periphery of the electrolyte layer 4. To explain, in a case where the electrochemical element E is used as a component of SOFC, gas is supplied from the back side of the metal substrate 1 to the electrode layer 2 through the through-holes 1a during the operation of SOFC. At a site where the electrolyte layer 4 is in contact with the metal substrate 1, gas leakage can be suppressed without providing a separate member such as a gasket. Moreover, in the present embodiment, the electrolyte layer 4 covers the entire periphery of the electrode layer 2, but a configuration in which the electrolyte layer 4 is provided on an upper part of the electrode layer 2 and the interlayer 3, and a gasket or the like is provided at the periphery may be adopted.
[0185] As a material for the electrolyte layer 4, yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (SSZ), gadolinium-doped ceria (GDC), yttrium-doped ceria (YDC), samarium-doped ceria (SDC), strontium- and magnesium-doped lanthanum gallate (LSGM), or the like can be used. In particular, zirconia-based ceramics are suitably used. In a case where the electrolyte layer 4 is made of the zirconia-based ceramics, an operating temperature of SOFC using the electrochemical element E can be made higher than that in a case of ceria-based ceramics. For example, in a case where the electrochemical element E is used for SOFC, and a system configuration in which a material, such as YSZ, which can exhibit a high electrolyte performance even in a high-temperature range of about 650° C. or higher is used as the material for the electrolyte layer 4, a hydrocarbon-based raw fuel such as a city gas and LPG is used as a raw fuel of the system, and the raw fuel is steam-reformed to become an anode gas of SOFC is adopted, it is possible to construct a highly efficient SOFC system in which heat generated in a cell stack of SOFC is used for reforming the raw fuel gas.
[0186] The electrolyte layer 4 is preferably formed by a low-temperature calcination method (a wet method using a calcination treatment in a low-temperature range without performing a calcination treatment in a high-temperature range of higher than 1,100° C.), and for example, the electrolyte layer 4 can be formed by performing an air spray method, a bar coat method, a dispenser method, a brush coating, and a spatula coating with a liquid composition, and performing a calcination treatment in a temperature range of 1100° C. or lower. In addition, the electrolyte layer 4 is preferably formed by a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. As a result of adopting these film formation processes that can be used in a low-temperature range, a electrolyte layer 4 that is dense and has high gastightness and gas barrier properties can be obtained without using calcination in a high-temperature range of higher than 1,100° C., for example. Therefore, the damage of the metal substrate 1 can be prevented, and the element interdiffusion between the metal substrate 1 and the electrode layer 2 can be prevented; thereby capable of achieving the electrochemical element E excellent in a performance and durability. In particular, using a low-temperature calcination method, a spray coating method, or the like is preferable because a low-cost element can be obtained. Furthermore, using the low-temperature calcination method and the spray coating method is more preferable because the electrolyte layer which is dense and has high gastightness and gas barrier properties can be easily obtained in a low-temperature range.
[0187] The electrolyte layer 4 is densely configured to shield gas leak of an anode gas and a cathode gas and to exhibit high ionic conductivity. A denseness of the electrolyte layer 4 is preferably 90% or greater, more preferably 95% or greater, and still more preferably 98% or greater. In a case where the electrolyte layer 4 is a uniform layer, the denseness thereof is preferably 95% or greater and more preferably 98% or greater. Moreover, when the electrolyte layer 4 is formed in a form of a plurality of layers, at least some of these layers preferably include a layer (a dense electrolyte layer) having a denseness of 98% or greater, and more preferably include a layer (a dense electrolyte layer) having a denseness of 99% or greater. This is because when such a dense electrolyte layer is included in a part of the electrolyte layer 4, the electrolyte layer that is dense and has high gastightness and gas barrier properties can be easily formed even in a case where the electrolyte layer 4 is formed in a form of a plurality of layers.
Reaction Preventing Layer
[0188] The reaction preventing layer 5 can be formed as a thin layer on the electrolyte layer 4. In a case of being provided as a thin layer, a thickness thereof can be, for example, about 1 .Math.m to 100 .Math.m, preferably about 2 .Math.m to 50 .Math.m, and more preferably about 4 .Math.m to 25 .Math.m. In a case where the thickness is set as described above, a sufficient performance can be ensured while reducing a cost by reducing a used amount of an expensive material for the reaction preventing layer. As a material of the reaction preventing layer 5 may be any material that can prevent a reaction between a component of the electrolyte layer 4 and a component of the counter electrode layer 6. For example, a ceria-based material or the like is used. As a result of introducing the reaction preventing layer 5 between the electrolyte layer 4 and the counter electrode layer 6, a reaction between constituent materials of the counter electrode layer 6 and constituent materials of the electrolyte layer 4 can be effectively suppressed, and long-term stability of the performance of the electrochemical element E can be improved. Forming the reaction preventing layer 5 by appropriately using a method in which the reaction preventing layer 5 can be formed at a treatment temperature of 1,100° C. or lower is preferable since the damage of the metal substrate 1 can be prevented, the element interdiffusion between the metal substrate 1 and the electrode layer 2 can be prevented, and the electrochemical element E excellent in a performance and durability can be obtained. For example, the formation can be performed by appropriately using a low-temperature calcination method (for example, a wet method using a calcination treatment in a low-temperature range without performing a calcination treatment in a high-temperature range of higher than 1,100° C.), a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. In particular, using a low-temperature calcination method, a spray coating method, or the like is preferable because a low-cost element can be obtained. Furthermore, using the low-temperature calcination method is more preferable because handling of raw materials becomes easy.
Counter Electrode Layer
[0189] The counter electrode layer 6 can be formed as a thin layer on the electrolyte layer 4 or the reaction preventing layer 5. In a case of being provided as a thin layer, a thickness thereof can be, for example, about 1 .Math.m to 100 .Math.m and preferably 5 .Math.m to 50 .Math.m. In a case where the thickness is set as described above, a sufficient electrode performance can be ensured while reducing a cost by reducing a used amount of an expensive material for the counter electrode layer. As a material for the counter electrode layer 6, for example, a complex oxide such as LSCF and lantern strontium manganate (LSM), a ceria-based oxide, and a mixture thereof can be used. In particular, the counter electrode layer 6 preferably contains a perovskite-type oxide containing two or more elements selected from the group consisting of La, Sr, Sm, Mn, Co, and Fe. The counter electrode layer 6 formed of the above materials functions as a cathode.
[0190] Forming the counter electrode layer 6 by appropriately using a method by which the counter electrode layer 6 can be formed at a treatment temperature of 1,100° C. or lower is preferable since the damage of the metal substrate 1 can be prevented, the element interdiffusion between the metal substrate 1 and the electrode layer 2 can be prevented, and the electrochemical element E excellent in a performance and durability can be obtained. For example, the formation can be performed by appropriately using a low-temperature calcination method (for example, a wet method using a calcination treatment in a low-temperature range without performing a calcination treatment in a high-temperature range of higher than 1,100° C.), a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. In particular, using a low-temperature calcination method, a spray coating method, or the like is preferable because a low-cost element can be obtained. Furthermore, using the low-temperature calcination method is more preferable because handling of raw materials becomes easy.
[0191] As described above, in the electrochemical element E according to the present invention, yttria-stabilized zirconia (YSZ) can be adopted for the electrolyte layer 4. The electrolyte layer 4 can be formed by using the coating composition b2 according to the present invention because of the advantage of obtaining the electrolyte layer 4 that is dense and that has high gastightness and gas barrier properties.
[0192] As another embodiment, an yttria-stabilized zirconia layer obtained by curing the coating composition b2 of the present application can be used as a part of the electrode layer 2 and the interlayer 3 (partial constituent material of a composite material). Furthermore, another interlayer (not illustrated) may be inserted between the electrolyte layer 4 and the reaction preventing layer 5, and the yttria-stabilized zirconia obtained by curing the coating composition b2 of the present application can also be used as a part of this interlayer.
Operation as Solid Oxide Fuel Cell
[0193] As a result of configuring the electrochemical element E as described above, the electrochemical element E can be used as a fuel cell of a solid oxide fuel cell. For example, a reduction gas (typically a fuel gas containing hydrogen) is supplied to the electrode layer 2 from the back surface of the metal substrate 1 through the through-holes 1a, and an oxidization gas (typically air containing oxygen) is supplied to the counter electrode layer 6 serving as a counter electrode of the electrode layer 2 to operate the electrochemical element E at a temperature of, for example, 600° C. or higher and 850° C. or lower. Then, oxygen O.sub.2 contained in the air in the counter electrode layer 6 reacts with an electron e.sup.- to generate an oxygen ion O.sup.2-. The oxygen ion O.sup.2- moves to the electrode layer 2 through the electrolyte layer 4 (see
Method for Producing Electrochemical Element
[0194] Next, a method for producing the electrochemical element E according to the present embodiment will be described.
[0195] In the following description, an example of forming an yttria-stabilized zirconia layer on a part of the electrode layer 2 and the interlayer 3 and further on the electrolyte layer 4 by using the coating composition b2 according to the present invention will be mainly described.
Metal Substrate Preparation Step
[0196] At a metal substrate preparation step, a plate material made of a Fe—Cr alloy having a predetermined shape can be prepared, and a large number of the through-holes 1a can be formed at predetermined positions of the plate material by laser processing or the like. This plate material may be subjected to a Co-plating treatment, and after the plating treatment, an oxidation treatment may be performed to form a metal oxide layer containing Co. This metal oxide layer will be formed as a metal oxide layer 1b (coating layer) in an electrode layer forming step described later.
Electrode Layer Forming Step
[0197] In an electrode layer forming step, the electrode layer 2 is formed as a thin film in a region wider than the region where the through-holes 1a are provided on the front surface of the metal substrate 1 obtained at the metal substrate preparation step. The through-holes of the metal substrate 1 can be provided by laser processing or the like. The electrode layer 2 can be formed by appropriately using a low-temperature calcination method (a wet method with a calcination treatment in a low-temperature range of 1,100° C. or lower), a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), or the like. Regardless of which method is used, it is desirable to carry out a method at a temperature of 1100° C. or lower in order to prevent deterioration of the metal substrate 1.
[0198] In a case where the electrode layer forming step is carried out by a low-temperature calcination method, specifically, material powder and a solvent (dispersion medium) are mixed to prepare material paste, and the material paste is applied to the front surface of the metal substrate 1. Here, the coating composition b2 according to the present invention can be used as a part of this material paste.
[0199] Then, the electrode layer 2 is compression molded (electrode layer smoothing step) and calcinated at 1100° C. or lower (electrode layer calcination step). The compression molding of the electrode layer 2 can be carried out by, for example, cold isostatic pressing (CIP, cold hydrostatic pressure) molding, roll pressure molding, rubber isostatic pressing (RIP) molding, or the like. The electrode layer 2 is suitably calcinated at a temperature of 800° C. or higher and 1,100° C. or lower. The order of the electrode layer smoothing step and the electrode layer calcination step can be exchanged.
[0200] In a case of forming the electrochemical element including the interlayer 3, the electrode layer smoothing step or the electrode layer calcination step is not carried out, or the electrode layer smoothing step or the electrode layer calcination step can be included in an interlayer smoothing step or an interlayer calcination step described later.
[0201] The electrode layer smoothing step can also be carried out by performing a lap forming or leveling treatment, a surface cutting and polishing treatment, or the like.
Diffusion Preventing Layer Forming Step
[0202] A diffusion preventing layer is the metal oxide layer 1b (coating layer) formed on the surface of the metal substrate 1 during a calcination step at the above-mentioned electrode layer forming step. In a case where the above-mentioned calcination step includes a calcination step carried out based on a condition of setting a calcinating atmosphere to an atmosphere with a low oxygen partial pressure, the effect of suppressing mutual diffusion of elements is high, and a high-quality metal oxide layer 1b having a low resistance value is formed, which is preferable. Including a case where the electrode layer forming step is carried out by a coating method without calcination, another diffusion preventing layer forming step may be included. For example, at the other diffusion preventing layer forming step, the metal substrate 1 is coated with Co thereon, and an oxidation treatment is then carried out to form the metal oxide layer 1b. Alternatively, for example, at the other diffusion preventing layer forming step, an intervening layer formed on the metal substrate 1 can be coated with Co, and the oxidation treatment can be then carried out to form the metal oxide layer 1b.
[0203] In both case, it is desirable to carry out the treatment at a treatment temperature of 1100° C. or lower, which can prevent damage to the metal substrate 1. In addition, the metal oxide layer 1b (diffusion preventing layer) may be formed on the surface of the metal substrate 1 during the calcination step at an interlayer forming step described later.
Interlayer Forming Step
[0204] At an interlayer forming step, the interlayer 3 is formed as a thin layer on the electrode layer 2 in the form of covering the electrode layer 2. The interlayer 3 can be formed by appropriately using a low-temperature calcination method (a wet method with a calcination treatment in a low-temperature range of 1,100° C. or lower), a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. Regardless of which method is used, it is desirable to carry out a method at a temperature of 1100° C. or lower in order to prevent deterioration of the metal substrate 1.
[0205] In a case where the interlayer forming step is carried out by the low-temperature calcination method, it is specifically performed as in the following example. First, material powder of the interlayer 3 and a solvent (dispersion medium) are mixed to prepare material paste, and the material paste is applied to the front surface of the metal substrate 1.
[0206] As a material of the interlayer, ceria-based ceramics such as gadolinium-doped ceria (GDC), yttrium-doped ceria (YDC), and samarium-doped ceria (SDC) are suitably used. Here, in a case where the coating composition b2 according to the present invention is contained in this material paste in advance, it can be used as a part of the interlayer 3 made of a composite material.
[0207] Then, the interlayer 3 is compression molded (interlayer smoothing step) and calcinated at 1100° C. or lower (interlayer calcination step). The compression molding of the interlayer 3 can be carried out by, for example, cold isostatic pressing (CIP, cold hydrostatic pressure) molding, roll pressure molding, rubber isostatic pressing (RIP) molding, or the like. The interlayer 3 is suitably calcinated at a temperature of 800° C. or higher and 1100° C. or lower. The reason why such a temperature is employed is because a high-strength interlayer 3 can be formed while preventing damage and deterioration of the metal substrate 1. In addition, the interlayer 3 is preferably calcinated at 1050° C. or lower and still more preferably calcinated at 1000° C. or lower. This is because the electrochemical element E can be formed while further preventing damage and deterioration of the metal substrate 1 as the calcination temperature of the interlayer 3 is lowered. The order of the interlayer smoothing step and the interlayer calcination step can be exchanged.
[0208] The interlayer smoothing step can also be carried out by performing a lap forming or leveling treatment, a surface cutting and polishing treatment, or the like.
Electrolyte Layer Forming Step
[0209] At an electrolyte layer forming step, the electrolyte layer 4 is formed as a thin layer on the interlayer 3 in a state of covering the electrode layer 2 and the interlayer 3. The electrolyte layer 4 can also be formed as a thin film having a thickness of 10 .Math.m or less. The electrolyte layer 4 is preferably formed by the low-temperature calcination method (a wet method of performing a calcination treatment in a low-temperature range of 1100° C. or lower) as described above, and for example, the electrolyte layer 4 can be formed by performing an air spray method, a bar coat method, a dispenser method, a brush coating, and a spatula coating with the coating composition b2 according to the present invention, and performing a calcination treatment in a temperature range of 1100° C. or lower. In addition, it is possible to use methods such as a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), and a CVD method. Regardless of which method is used, it is desirable to carry out a method at a temperature of 1100° C. or lower in order to prevent deterioration of the metal substrate 1.
[0210] In order to form a high-quality electrolyte layer 4 that is dense and has high gastightness and gas barrier properties in a temperature range of 1100° C. or lower, it is desirable that the coating composition b2 according to the present invention is used to form the electrolyte layer 4 in the electrolyte layer forming step by a low-temperature calcination method. In that case, a material of the electrolyte layer 4 can be applied onto an underlying layer by an air spray method or the like and can be subjected to a calcination treatment at a temperature of 1100° C. or lower to form the electrolyte layer 4.
Reaction Preventing Layer Forming Step
[0211] At the reaction preventing layer forming step, the reaction preventing layer 5 is formed on the electrolyte layer 4 as a thin layer. The reaction preventing layer 5 can be formed by appropriately using a low-temperature calcination method, a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. Regardless of which method is used, it is desirable to carry out a method at a temperature of 1100° C. or lower in order to prevent deterioration of the metal substrate 1. In order to flatten an upper surface of the reaction preventing layer 5, for example, a leveling treatment or a surface cutting and polishing treatment may be performed after forming the reaction preventing layer 5, or press processing may be performed after wet formation and before calcination.
Counter Electrode Layer Forming Step
[0212] At the counter electrode layer forming step, the counter electrode layer 6 is formed on the reaction preventing layer 5 as a thin layer. The counter electrode layer 6 can be formed by appropriately using a low-temperature calcination method, a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, and a cold spraying method), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. Regardless of which method is used, it is desirable to carry out a method at a temperature of 1100° C. or lower in order to prevent deterioration of the metal substrate 1.
[0213] As described above, the electrochemical element E can be produced. A base material with an electrode layer for a metal-supported electrochemical element can be produced by performing the electrode layer forming step and the interlayer forming step described above.
[0214] A form in which the electrochemical element E does not include either or both the interlayer 3 and the reaction preventing layer 5 is possible. That is, a form in which the electrode layer 2 and the electrolyte layer 4 are formed to be in contact with each other or a form in which the electrolyte layer 4 and the counter electrode layer 6 are formed to be in contact with each other is also possible. In this case, in the above-mentioned producing method, the interlayer forming step and the reaction preventing layer forming step are not provided.
Electrochemical Element, Electrochemical Module, and Electrochemical Device
[0215] An example of a solid oxide fuel cell with an electrochemical element E, an electrochemical module M, an electrochemical device Y, and an energy system Z will be described with reference to
[0216] In the electrochemical element E of this form, as illustrated in
[0217] As illustrated in
[0218] As illustrated in
[0219] The supplied gas flows through the inside of the tubular support TS and is supplied to the electrode layer 2 through the through-holes 1a of the metal substrate 1.
[0220]
[0221] The energy system Z includes the electrochemical device Y and a heat exchanger 53 as an exhaust heat utilization section for reusing heat discharged from the electrochemical device Y.
[0222] The electrochemical device Y includes an electrochemical module M, a fuel supply section that includes a desulfurizer 31 and a reformer 34 and that supplies a fuel gas containing a reduction gas to the electrochemical module M, and an inverter 38 as an electric power conversion section for extracting electric power from the electrochemical module M. Therefore, this electrochemical device serves as a power generation device that receives fuel to generate electricity.
[0223] Specifically, the electrochemical device Y includes a desulfurizer 31, a reforming water tank 32, a vaporizer 33, a reformer 34, a blower 35, a combustion section 36, an inverter 38, a controller 39, a storage container 40, and an electrochemical module M.
[0224] The desulfurizer 31 removes (desulfurizes) a sulfur compound component contained in a hydrocarbon-based raw fuel such as a city gas. In a case where a sulfur compound is contained in a raw fuel, the desulfurizer 31 can be provided to suppress the influence of the sulfur compound on the reformer 34 or the electrochemical elements E. The vaporizer 33 produces steam from reforming water supplied from the reforming water tank 32. The reformer 34 steam-reforms a raw fuel desulfurized in the desulfurizer 31 by using the steam produced in the vaporizer 33 to produce a reformed gas containing hydrogen.
[0225] The electrochemical module M performs power generation by using a reformed gas supplied from the reformer 34 and air supplied from the blower 35 to cause an electrochemical reaction between the reformed gas and the air. In the combustion section 36, a reaction exhaust gas discharged from the electrochemical module M is mixed with air to combust combustible components in the reaction exhaust gas.
[0226] The electrochemical module M includes the plurality of the electrochemical elements E and the gas manifold 17. The plurality of the electrochemical elements E are disposed in parallel in a state of being electrically connected to each other, and each end (lower end) of the electrochemical elements E is fixed to the gas manifold 17. The electrochemical element E performs power generation by causing an electrochemical reaction between the reformed gas supplied through the gas manifold 17 and air supplied from the blower 35.
[0227] The inverter 38 adjusts output power of the electrochemical module M to electric power having the same voltage and the same frequency as those of electric power received from a commercial system (not illustrated). Therefore, the inverter 38 is an electric power converter that extracts electric power from the electrochemical element E or the electrochemical module M. The controller 39 controls operations of the electrochemical device Y and the energy system Z.
[0228] The vaporizer 33, the reformer 34, the electrochemical module M, and the combustion section 36 are housed in the storage container 40. The reformer 34 reforms a raw fuel by using combustion heat generated by the combustion of the reaction exhaust gas in the combustion section 36.
[0229] The raw fuel is supplied to the desulfurizer 31 through the raw fuel supply channel 42 by an operation of a booster pump 41. The reforming water in the reforming water tank 32 is supplied to the vaporizer 33 through a reforming water supply channel 44 by an operation of a reforming water pump 43. The raw fuel supply channel 42 is joined at a location of downstream of the desulfurizer 31 into the reforming water supply channel 44, and supplies the reforming water and the raw fuel, which are joined at a location outside the storage container 40 to the vaporizer 33 provided inside the storage container 40.
[0230] The reforming water is vaporized by the vaporizer 33 to be steam. The raw fuel containing steam generated by the vaporizer 33 is supplied to the reformer 34 through a steam-containing raw fuel supply channel 45. The raw fuel is steam-reformed in the reformer 34 to generate a reformed gas whose main component is a hydrogen gas (a fuel gas containing hydrogen, which is the reduction gas described so far). The reformed gas generated by the reformer 34 is supplied to the gas manifold 17 of the electrochemical module M through a reformed gas supply channel 46.
[0231] The reformed gas supplied to the gas manifold 17 is distributed to the plurality of the electrochemical elements E, and is supplied from a lower end of a connection portion between the electrochemical elements E and the gas manifold 17 to the electrochemical elements E. Mainly hydrogen in the reformed gas is used for an electrochemical reaction in the electrochemical elements E. Therefore, the reformer 34 is a fuel converter that supplies a gas containing the reduction gas to the electrochemical elements E or the electrochemical module M. The reaction exhaust gas containing a residual hydrogen gas that is not used in the reaction is discharged from upper ends of the electrochemical elements E to the combustion section 36.
[0232] The reaction exhaust gas is combusted in the combustion section 36 and becomes a combustion exhaust gas, and the combustion exhaust gas discharged to the outside of the storage container 40 from a combustion exhaust gas outlet 50. A combustion catalyst section 51 (for example, a platinum-based catalyst) is disposed at the combustion exhaust gas outlet 50 to combust and remove reduction gases such as carbon monoxide and hydrogen contained in the combustion exhaust gas. The combustion exhaust gas discharged from the combustion exhaust gas outlet 50 is transmitted to the heat exchanger 53 through a combustion exhaust gas discharge channel 52.
[0233] The heat exchanger 53 exchanges heat between the combustion exhaust gas generated by combustion in the combustion section 36 and cold water supplied to generate hot water. That is, the heat exchanger 53 operates as an exhaust heat utilization section for reusing the heat discharged from the electrochemical device Y.
[0234] In addition, instead of the exhaust heat utilization section, a reaction exhaust gas utilization section (not illustrated) may be provided for utilizing the reaction exhaust gas discharged (without combustion) from the electrochemical module M. The reaction exhaust gas contains a residual hydrogen gas that has not been used in the reaction in the electrochemical elements E. In the reaction exhaust gas utilization section, the residual hydrogen gas is used to utilize heat by combustion and power generation by a fuel cell or the like, so that energy can be effectively utilized.
Another Embodiment of Electrochemical Module
[0235]
[0236] Regarding the electrochemical module M according to another embodiment, the electrochemical module M is configured to stack the above-mentioned electrochemical elements E with an intercell connection member 71 interposed therebetween.
[0237] The intercell connection member 71 is a plate-shaped member having conductivity and no gas permeability, and grooves 72 orthogonal to each other are formed on the front surface and the back surface. As the intercell connection member 71, a metal such as stainless steel or a metal oxide can be used.
[0238] As illustrated in
[0239] In a case where the electrochemical module M is operated as a fuel cell, an oxidization gas (typically, air containing oxygen) is supplied to the first gas flow channels 72a, and a reduction gas (typically, a fuel gas containing hydrogen) is supplied to the second gas flow channels 72b. Then, a reaction in the electrochemical module M as a fuel cell proceeds in the electrochemical elements E, and electromotive force and current are generated. The generated electric power is extracted from the intercell connection members 71 on both ends of the stacked electrochemical elements E to the outside of the electrochemical module M.
[0240] In the present embodiment, the grooves 72 orthogonal to each other are formed on the front surface and the back surface of each intercell connection member 71, but the grooves 72 parallel to each other can also be formed on the front surface and the back surface of the intercell connection member 71.
Another Embodiment
[0241] (1) In the above-mentioned embodiment, the electrochemical element E is used for the solid oxide fuel cell, but the electrochemical element E can also be used for a solid oxide electrolysis cell, an oxygen sensor obtained by using a solid oxide, or the like.
[0242] Hereinafter, an example of using the electrochemical element E as a solid oxide electrolysis cell will be described with reference to the drawings. As illustrated above, this example is an example in which the electrochemical device Y according to the present invention is a hydrocarbon production system 100, and the electrochemical element E is operated by supplying a predetermined raw gas and electric power to serve as an electrolytic reaction section 10. That is, as a result of supplying water H.sub.2O and carbon dioxide CO.sub.2 to the electrolytic reaction section 10, carbon monoxide CO and hydrogen H.sub.2 as raw materials for synthesizing hydrocarbons are obtained by decomposing water H.sub.2O and carbon dioxide CO.sub.2. Then, a hydrocarbon can be obtained in a hydrocarbon synthesis reaction section 30.
[0243]
[0244] As can be seen from
[0245] The electrolytic reaction section 10 is a section that electrolyzes at least a part of a gas flowing thereinto, the first catalytic reaction section 20 is a reverse water gas shift reaction section in which at least a part of a gas flowing thereinto is subjected to a reverse water gas shift reaction, and the second catalytic reaction section 30 is a hydrocarbon synthesis reaction section that synthesizes at least a part of a gas flowing thereinto into a hydrocarbon. Here, the synthesized hydrocarbon is mainly CH.sub.4 (hydrocarbon having one carbon atom), but may include lower saturated hydrocarbon having 2 to 4 carbon atoms and the like. Furthermore, a hydrocarbon having a larger number of carbon atoms than the lower saturated hydrocarbon and being in no saturated state is also synthesized. These heavy hydrocarbons can be collected and separated by the heavy hydrocarbon separating section 70 as a gas released from the second catalytic reaction section 30 cools.
[0246] The water separating section 80 and the carbon dioxide separating section 90 are sections in which at least some of predetermined components (H.sub.2O and CO.sub.2 in the order of description) are removed from the gas flowing inside. As illustrated in the figure, the components removed and recovered through these sections are returned to a predetermined section of the system through a water return channel 81 and a carbon dioxide return channel 91 and are reused. H.sub.2O and CO.sub.2 returned through the water return channel 81 and the carbon dioxide return channel 91 are illustrated on both return channels 81 and 91, respectively.
[0247] As a result, this hydrocarbon production system 100 is established as a carbon closed system that does not substantially release CO.sub.2 to the outside of the system.
[0248] In the figure, a gas flowing into each section is illustrated at the front side of each section, and a gas released from the section is illustrated at the rear side.
[0249] H.sub.2O and CO.sub.2 as raw gases flow in the electrolytic reaction section 10 and are electrolyzed internally, H.sub.2O is decomposed into H.sub.2 and O.sub.2, some CO.sub.2 is decomposed into CO and O.sub.2, which are released.
[0250] The reaction is described as follows.
##STR00002##
##STR00003##
These Formulae 1 and 2 are also illustrated in the box illustrating the electrolytic reaction section 10 of
[0251] At least H.sub.2 and CO.sub.2 flow in the first catalytic reaction section 20 (reverse water gas shift reaction section), a reverse water gas shift reaction occurs inside the first catalytic reaction section 20, CO.sub.2 becomes CO, and H.sub.2 becomes H.sub.2O, which are released.
[0252] The reaction is described as the following equilibrium reaction, but the reverse water gas shift reaction is a reaction (CO.sub.2 and H.sub.2 react with each other to form CO and H.sub.2O) in which a reaction described by the following Formula 3 proceeds to the right.
##STR00004##
[0253] This Formula 3 is also illustrated in the box illustrating the first catalytic reaction section 20 (reverse water gas shift reaction section) in
[0254] As this kind of the reverse water gas shift catalyst cat1, the inventors have considered that a catalyst obtained by supporting any one of nickel or iron or both nickel and iron on one or more carriers cb1 (metal oxide carriers) selected from ceria-based metal oxides, zirconia-based metal oxides, and alumina-based metal oxides is preferable as a catalyst activation component ca1 (metal catalyst).
[0255] At least H.sub.2 and CO flow into the second catalytic reaction section 30 (hydrocarbon synthesis reaction section) to synthesize a hydrocarbon through a catalytic reaction.
[0256] For example, a reaction in which CH.sub.4 is synthesized from CO and H.sub.2 is described as the following equilibrium reaction, and the reaction in which CH.sub.4 is synthesized from CO and H.sub.2 is a reaction in which the reaction described by the following Formula 4 proceeds to the right (CO and H.sub.2 react with each other to form CH.sub.4 and H.sub.2O).
##STR00005##
[0257] This Formula 4 is also illustrated in the box illustrating the second catalytic reaction section 30 (hydrocarbon synthesis reaction section) in
[0258] As this kind of the hydrocarbon synthesis catalyst cat2, the inventors have considered that a catalyst obtained by supporting at least ruthenium on a carrier cb2 (metal oxide carrier), for example, alumina or the like, is preferable as a catalyst activation component ca2.
[0259] Furthermore, the equilibrium reaction of (Formula 3) also occurs at this section.
[0260] A Fischer-Tropsch (FT) synthesis reaction can proceed depending on the kinds of the catalyst used in the second catalytic reaction section 30, so that hydrocarbons such as ethane and propane are synthesized from CO and H.sub.2.
[0261] Generated H.sub.2O is separated in the water separating section 80 and returned to the upstream of the electrolytic reaction section 10 through the water return channel 81 (water recycling line).
[0262] Generated CO.sub.2 is separated in the carbon dioxide separating section 90 and returned to the upstream of the electrolytic reaction section 10 through the carbon dioxide return channel 91 (carbon dioxide recycling line).
[0263] As a result, in this hydrocarbon production system 100, the hydrocarbon is finally synthesized and can be supplied to the outside.
[0264]
[0265] In this figure, in order to clarify the electrochemical reaction system, the interlayer 3 and the reaction preventing layer 5 of the electrochemical element E in
[0266] This electrolytic cell unit U is also configured to include the electrochemical element E in which the electrode layer 2 and the counter electrode layer 6 are formed with the electrolyte layer 4 interposed therebetween, the metal substrate 1 as a metal support that serves as a separator, the U-shaped member 7 that serves as a supply channel forming member, and the current-collecting member 26 that serves as a supply channel forming member, and adopts a configuration in which an electrode layer-side gas supply channel 7a and a counter electrode layer-side gas supply channel 26a are formed. H.sub.2O and CO.sub.2 to be electrolyzed are supplied to the electrode layer-side gas supply channel 7a. On the other hand, an air g2 (O.sub.2) that is an example of an oxygen-containing gas is supplied to the counter electrode layer-side gas supply channel 26a. The electrochemical module M can be constructed by stacking (assembling) the electrolytic cell units U in the left-right direction of
[0267] As described above, the electrolyte layer 4 and the electrode layer 2 as a part thereof can be constructed by using the coating composition b2 according to the present invention.
[0268] This configuration of another implementation is an example in which the electrochemical element E is operated as the electrolytic reaction section 10, but as can be seen from
[0269] However, the reverse water gas shift catalyst cat1 is applied on an inner surface of the electrode layer-side gas supply channel 7a (an inner surface of the U-shaped member 7 on the supply channel side, a surface of the metal substrate 1 opposite to a surface on which the electrode layer 2 is formed, and surfaces of a plurality of through-holes 1a). This coating layer 20b is illustrated by a thick solid line.
[0270] Furthermore, the electrode layer-side gas supply channel 7a extends over the electrolytic reaction section 10, and the coating layer 20b is also provided on the extension side. Furthermore, a hydrocarbon synthesis catalyst cat 2 is applied to the tip thereof, and a coating layer 30b is provided to form the hydrocarbon synthesis reaction section 30.
[0271] As a result, in this configuration, in a case where the hydrocarbon synthesis reaction section 30 is the electrochemical element E or an assembly of the electrochemical elements E, the hydrocarbon synthesis reaction section 30 is an electric power converter that supplies electric power to the electrochemical module M that is the assembly.
[0272] A hydrocarbon can be obtained in the hydrocarbon synthesis reaction section 30 by using a gas obtained in the electrolytic reaction section 10 and the reverse water gas shift reaction section 20.
[0273] (2) In the above embodiment, the metal-supported solid oxide fuel cell having a metal substrate 1 as a support is used, but in the present invention, an electrode-supported solid oxide fuel cell having the electrode layer 2 or the counter electrode layer 6 as a support, or an electrolyte-supported solid oxide fuel cell having the electrolyte layer 4 as a support can be used. In these cases, the electrode layer 2, the counter electrode layer 6, or the electrolyte layer 4 can be made to have a required thickness, so that the function as a support can be obtained.
[0274] (3) In the above embodiment, as a material of the electrode layer 2, for example, a composite material such as NiO—GDC, Ni—GDC, NiO—YSZ, Ni—YSZ, CuO—CeO.sub.2, or Cu—CeO.sub.2 was used, and as a material of the counter electrode layer 6, for example, a composite oxide such as LSCF or LSM was used. The electrochemical element E configured in this way can be used as a solid oxide fuel cell by supplying hydrogen gas to the electrode layer 2 to serve as a fuel electrode and supplying air to the counter electrode layer 6 to serve as an air electrode. It is also possible to modify this configuration to configure the electrochemical element E so that the electrode layer 2 can serve as an air electrode and the counter electrode layer 6 can serve as a fuel electrode. That is, a composite oxide such as LSCF or LSM is used as a material of the electrode layer 2, and for example, a composite material such as NiO—GDC, Ni—GDC, NiO—YSZ, Ni—YSZ, CuO—CeO.sub.2, or Cu—CeO.sub.2 is used as a material of the counter electrode layer 6. In the electrochemical element E configured as described above, air can be supplied to the electrode layer 2 to serve as an air electrode, a hydrogen gas can be supplied to the counter electrode layer 6 to serve as a fuel electrode, and the electrochemical element E can be a solid oxide fuel cell.
[0275] (4) In the above embodiment, an example in which the composite oxide film containing Co is formed on the surface of the Fe—Cr alloy as the metal substrate 1 to prevent volatilization of Cr and the like from this material, but one or more of the U-shaped member 7 as a separator, the gas manifold 17, the current-collecting member 26, and the intercell connection member 71 as an interconnector may be made of this type of alloy member.
[0276] On the other hand, as this type of oxide film, an oxide film containing only Co may be formed on the surface of the Fe—Cr alloy. It is effective to the volatilization of Cr.
[0277] The configurations disclosed in the above embodiments can be applied in combination with the configurations disclosed in other embodiments as long as there is no contradiction. The embodiments disclosed in the present specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified without departing from the objective of the present invention.
REFERENCE SIGNS LIST
[0278] 1: Metal substrate (metal support) [0279] 1a: Through-hole [0280] 2: Electrode layer [0281] 3: Interlayer [0282] 4: Electrolyte layer [0283] 5: Reaction preventing layer [0284] 6: Counter electrode layer [0285] 7: U-shaped member (separator) [0286] 10: Electrolytic reaction section [0287] 17: Gas manifold (manifold) [0288] 20: First catalytic reaction section (reverse water gas shift reaction section) [0289] 26: Current-collecting member [0290] 30: Second catalytic reaction section (hydrocarbon synthesis reaction section/fuel converter) [0291] 31: Desulfurizer [0292] 32: Reforming water tank [0293] 33: Vaporizer [0294] 34: Reformer (fuel converter) [0295] 35: Blower [0296] 36: Combustion section [0297] 38: Inverter (electric power converter) [0298] 39: Controller [0299] 40: Storage container [0300] 41: Booster pump [0301] 42: Raw fuel supply channel [0302] 43: Reforming water pump [0303] 44: Reforming water supply channel [0304] 45: Steam-containing raw fuel supply channel [0305] 46: Reformed gas supply channel [0306] 50: Combustion exhaust gas outlet [0307] 51: Combustion catalyst section [0308] 52: Combustion exhaust gas discharge channel [0309] 53: Heat exchanger (exhaust heat utilization section) [0310] 70: Heavy hydrocarbon separating section [0311] 71: Intercell connection member (interconnector) [0312] 72: Groove [0313] 72a: First gas flow channel [0314] 72b: Second gas flow channel [0315] 80: Water separating section [0316] 90: Carbon dioxide separating section [0317] 100: Hydrocarbon production system E: Electrochemical element [0318] M: Electrochemical module [0319] Pa: Yttria-stabilized zirconia fine particles [0320] U: Electrolytic cell unit [0321] Y: Electrochemical device [0322] Z: Energy system [0323] o: Zirconium alkoxide [0324] p: Yttrium compound [0325] q: Chelate compound [0326] r: Catalyst [0327] s: Water [0328] t: Organic solvent