WO2013150939A1 - 燃料電池用電極触媒の製造方法、燃料電池用電極触媒およびその用途 - Google Patents
燃料電池用電極触媒の製造方法、燃料電池用電極触媒およびその用途 Download PDFInfo
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- WO2013150939A1 WO2013150939A1 PCT/JP2013/058990 JP2013058990W WO2013150939A1 WO 2013150939 A1 WO2013150939 A1 WO 2013150939A1 JP 2013058990 W JP2013058990 W JP 2013058990W WO 2013150939 A1 WO2013150939 A1 WO 2013150939A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M2008/1095—Fuel cells with polymeric electrolytes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0082—Organic polymers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/9008—Organic or organo-metallic compounds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- the present invention relates to a method for producing a fuel cell electrode catalyst, a fuel cell electrode catalyst, and use thereof.
- a polymer electrolyte fuel cell In a polymer electrolyte fuel cell (PEFC), a polymer solid electrolyte is sandwiched between an anode and a cathode, fuel is supplied to the anode, oxygen or air is supplied to the cathode, and oxygen is reduced at the cathode to extract electricity. It is a type of fuel cell. Hydrogen or methanol is mainly used as the fuel.
- a layer containing a catalyst (hereinafter referred to as “for fuel cell”) is provided on the cathode (air electrode) surface or anode (fuel electrode) surface of the fuel cell. Also referred to as an “electrode catalyst layer”).
- a noble metal is generally used, and noble metals such as platinum and palladium, which are stable at a high potential and have high activity, have been mainly used.
- noble metals are expensive and have a limited amount of resources, various catalysts that can be substituted (for example, metal atoms, carbon atoms, Development of fuel cell electrode catalysts containing nitrogen and oxygen atoms is underway.
- Patent Document 4 discloses the production of an electrode catalyst for a fuel cell in which metal carbonitride is heated in an inert gas containing oxygen gas and the obtained metal carbonitride is brought into contact with an acidic solution. According to this manufacturing method, the durability against repetitive changes in current and voltage is superior to that of the conventional method, and even after such repetition, the maximum output density is difficult to decrease.
- an electrode catalyst for a fuel cell made of carbonitride and a fuel cell using the catalyst are provided.
- the present invention provides an electrode catalyst for a fuel cell that can provide high durability and high maximum output density even when the fuel cell is continuously operated for a long time, a method for producing the same, a fuel cell using the catalyst, and the like.
- the purpose is that.
- the present inventors have found that the above problem can be solved by producing a fuel cell electrode catalyst by bringing a catalyst precursor containing copper as a metal element into contact with an acidic solution.
- the present invention relates to the following [1] to [13], for example.
- [1] Including a step of preparing a catalyst precursor containing each of atoms of a metal element, carbon, nitrogen, and oxygen and containing copper as the metal element, and a contact step of contacting the catalyst precursor with an acidic solution to obtain a catalyst.
- a fuel cell electrode catalyst layer comprising the fuel cell electrode catalyst according to [8] above.
- a membrane electrode assembly comprising a cathode, an anode, and an electrolyte membrane disposed between the cathode and the anode, wherein the cathode and / or the anode is an electrode according to the above [10]. .
- a fuel cell comprising the membrane electrode assembly according to [11] above.
- an electrode catalyst for a fuel cell that can obtain high durability and high maximum output density even when the fuel cell is continuously operated for a long time, a method for producing the same, a fuel cell using the catalyst, and the like. Provided.
- FIG. 1 is a graph evaluating the durability of single cells of the polymer electrolyte fuel cells of Comparative Example 1 and Example 1.
- FIG. 2 is a graph evaluating the durability of the single cells of the polymer electrolyte fuel cells of Comparative Example 2 and Example 2.
- FIG. 3 is a graph for evaluating the durability of single cells of the polymer electrolyte fuel cells of Comparative Example 3, Example 3 and Comparative Example 7.
- FIG. 4 is a graph evaluating the durability of the single cells of the polymer electrolyte fuel cells of Comparative Example 4, Example 4 and Comparative Example 8.
- FIG. 5 is a graph evaluating the durability of single cells of the polymer electrolyte fuel cells of Comparative Example 5 and Example 5.
- FIG. 6 is a graph evaluating the durability of single cells of the polymer electrolyte fuel cells of Comparative Example 6 and Example 6.
- the method for producing a fuel cell electrode catalyst according to the present invention comprises: Including a step of preparing a catalyst precursor containing each atom of metal element, carbon, nitrogen and oxygen, and copper as the metal element, and a contact step of obtaining a catalyst by contacting the catalyst precursor with an acidic solution It is characterized by.
- atoms and ions are described as “atoms” without strictly distinguishing them.
- a catalyst precursor containing each atom of a metal element, carbon, nitrogen, and oxygen and containing copper as the metal element is prepared.
- the metal element preferably further contains iron. Further, it may contain at least one metal element (M3) selected from the group consisting of sodium, titanium, zirconium, zinc and tantalum.
- M3 metal element selected from the group consisting of sodium, titanium, zirconium, zinc and tantalum.
- the proportion of copper in the metal element contained in the catalyst precursor is preferably 10 to 99 mol%, more preferably 50 to 95 mol%, and the proportion of iron is preferably 1 to 20 mol%, more preferably. Is 4 to 15 mol%, and the ratio of the metal element (M3) is preferably 85 mol% or less, more preferably 0.1 to 46 mol%.
- step (1) at least a metal compound (1), a nitrogen-containing organic compound (2), a solvent, and optionally a compound (3) described later are mixed to obtain a precursor production solution.
- the procedure (ii) is preferable.
- the metal compound (1) is, for example, a metal halide to be described later, the procedure (i) is preferable, and when the metal compound (1) is, for example, a metal alkoxide or a metal complex to be described later. Procedure (ii) is preferred.
- the mixing operation is preferably performed with stirring in order to increase the dissolution rate of each component in the solvent.
- the solution of the metal compound (1) is added little by little to the solution of the nitrogen-containing organic compound (2) or the solution of the nitrogen-containing organic compound (2) and the compound (3) (that is, the entire amount is once added). It is also preferable to not add to.
- the precursor production solution contains a reaction product of the metal compound (1) and the nitrogen-containing organic compound (2).
- the solubility of the reaction product in the solvent varies depending on the combination of the metal compound (1), the nitrogen-containing organic compound (2), the solvent, and the like.
- the precursor production solution depends on the type of the solvent and the type of the nitrogen-containing organic compound (2). Even if it is contained, it is a small amount (for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less) of the total amount of the solution.
- the metal compound (1) is a metal halide
- the metal solution (1) is contained in the precursor production solution, depending on the type of solvent and the type of the nitrogen-containing organic compound (2). Precipitates that are considered to be reaction products of the nitrogen-containing organic compound (2) are likely to be formed.
- step (1) the metal compound (1), the nitrogen-containing organic compound (2), a solvent, and optionally the compound (3) are placed in a pressurizable container such as an autoclave, and a pressure higher than normal pressure is applied. However, mixing may be performed.
- the temperature at which the metal compound (1), the nitrogen-containing organic compound (2), and a solvent are optionally mixed with the compound (3) is, for example, 0 to 60 ° C. It is estimated that a complex is formed from the metal compound (1) and the nitrogen-containing organic compound (2). If this temperature is excessively high, the complex is hydrolyzed when the solvent contains water, and the hydroxide It is considered that an excellent catalyst cannot be obtained using the catalyst precursor. If the temperature is excessively low, the metal compound (1) is precipitated before the complex is formed, It is considered that an excellent catalyst cannot be obtained using the catalyst precursor.
- Metal compound (1) Part or all of the metal compound (1) contains copper.
- the metal compound (1) preferably contains iron and may contain at least one metal element (M3) selected from the group consisting of sodium, titanium, zirconium, zinc and tantalum.
- the metal compound (1) preferably has at least one selected from an oxygen atom and a halogen atom, and specific examples thereof include a metal phosphate, a metal sulfate, a metal nitrate, and a metal organic acid salt.
- Metal acid halides intermediate hydrolysates of metal halides
- metal alkoxides metal halides
- metal halides and metal hypohalites metal complexes. Products, carbonates, sulfates, nitrates, acetates, chlorides, etc.). These may be used alone or in combination of two or more.
- the metal alkoxide is preferably the metal isopropoxide, ethoxide or butoxide.
- the metal alkoxide may have one type of alkoxy group or may have two or more types of alkoxy groups.
- metal compound (1) having an oxygen atom metal alkoxide, acetylacetone complex, metal acid chloride, metal sulfate and metal nitrate are preferable, and metal alkoxide and acetylacetone complex are more preferable from the viewpoint of cost. From the viewpoint of solubility, metal alkoxides and acetylacetone complexes are more preferable.
- metal halide metal chloride, metal bromide and metal iodide are preferable, and as the metal acid halide, metal acid chloride, metal acid bromide and metal acid iodide are preferable.
- the metal perhalogenate is preferably a metal perchlorate
- the metal hypohalite is preferably a metal hypochlorite.
- the compound containing copper among the metal compound (1) Copper (II) ethoxide, copper (II) isopropoxide, copper (II) butoxide, copper (II) pentoxide, copper (II) acetylacetonate, bisdiethylamino copper, bis (2,2,6,6-tetramethyl) -3,5-heptanedione) copper, copper (II) hexafluoroacetylacetonate, bis-1-methoxy-2-methyl-2-propoxycopper (II), copper dichloride, copper oxychloride, copper dibromide , Copper compounds such as copper oxybromide, copper diiodide, and copper oxyiodide. These compounds may be used individually by 1 type, and may use 2 or more types together.
- the resulting catalyst becomes fine particles with a uniform particle size, and because its activity is high, Copper dichloride, copper oxychloride, copper (II) ethoxide, copper (II) isopropoxide, copper (II) butoxide, copper (II) acetylacetonate are preferred, Copper dichloride, copper oxychloride, copper (II) ethoxide, copper (II) isopropoxide, and copper (II) acetylacetonate are more preferable.
- the resulting catalyst becomes fine particles with a uniform particle size, and its activity is high, Iron trichloride, iron dichloride, iron oxychloride, iron (III) ethoxide, iron (III) isopropoxide, iron (III) butoxide, iron (III) acetylacetonate, iron (III) isopropoxide acetylacetonate (Fe (acac) (O-iPr) 2 , Fe (acac) 2 (O-iPr)), potassium ferrocyanide, potassium ferricyanide, ammonium ferrocyanide, ammonium ferricyanide, iron (II) acetate, iron nitrate (II Is preferred, Iron trichloride, iron dichloride, iron (III) ethoxide, iron (III) isopropoxide, iron (III) butoxide, iron (III) acetylacetonate, potassium ferrocyanide, potassium ferricyanide, ammonium ferrocyanide, potassium ferr
- Sodium compounds such as sodium hydroxide, sodium carbonate, sodium sulfate, sodium nitrate, sodium acetate, sodium chloride; Titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetrapentoxide, titanium tetraacetylacetonate, titanium diisopropoxide diacetylacetonate (Ti (acac) 2 (O-iPr) 2 ) titanium oxydiacetyl Acetonate, tris (acetylacetonato) titanium chloride ([Ti (acac) 3 ] 2 [TiCl 6 ]), titanium tetrachloride, titanium trichloride, titanium oxychloride, titanium tetrabromide, titanium tribromide Titanium compounds such as titanium oxybromide, titanium tetraiodide,
- the resulting catalyst becomes fine particles with a uniform particle size, and its activity is high, Sodium hydroxide, sodium carbonate, sodium acetate, sodium chloride, Titanium tetraisopropoxide, titanium tetraacetylacetonate, titanium diisopropoxide diacetylacetonate (Ti (acac) 2 (O-iPr) 2 ), Zirconium tetraethoxide, zirconium tetrachloride, zirconium oxychloride, zirconium tetraisopropoxide, zirconium tetrabutoxide, zirconium tetraacetylacetonate, zirconium diisopropoxide diacetylacetonate (Zr (acac) 2 (O-iPr) 2 ) , Zinc dichloride, zinc oxychloride, zinc ethoxide, zinc isopropoxide, zinc butoxide, zinc acet
- the proportion of copper in the metal elements contained in all the metal compounds (1) is preferably 10 to 99 mol%, more preferably 50 to 95 mol%, and the proportion of iron is preferably 1 to 20 mol%. %, More preferably 4 to 15 mol%, and the ratio of the metal element (M3) is preferably 85 mol% or less, more preferably 0.1 to 46 mol%.
- the nitrogen-containing organic compound (2) is preferably a compound that can be a ligand capable of coordinating to the metal atom in the metal compound (1) (preferably a compound that can form a mononuclear complex). More preferred are compounds that can be bidentate (preferably bidentate or tridentate) (can form chelates).
- the said nitrogen containing organic compound (2) may be used individually by 1 type, and may use 2 or more types together.
- the nitrogen-containing organic compound (2) is preferably an amino group, nitrile group, imide group, imine group, nitro group, amide group, azide group, aziridine group, azo group, isocyanate group, isothiocyanate group, oxime group, Functional groups such as diazo group and nitroso group, or pyrrole ring, porphyrin ring, pyrrolidine ring, imidazole ring, triazole ring, pyridine ring, piperidine ring, pyrimidine ring, pyrazine ring, purine ring, etc. (these functional groups and rings) Are also referred to as “nitrogen-containing molecular groups”).
- the nitrogen-containing organic compound (2) has a nitrogen-containing molecular group in the molecule, the nitrogen-containing organic compound (2) can be more strongly coordinated with the metal atom derived from the metal compound (1) through mixing in the step (1). it is conceivable that.
- an amino group, an imine group, an amide group, a pyrrole ring, a pyridine ring and a pyrazine ring are more preferable, an amino group, an imine group, a pyrrole ring and a pyrazine ring are more preferable, and an amino group and a pyrazine ring are preferable.
- nitrogen-containing organic compound (2) examples include melamine, ethylenediamine, triazole, acetonitrile, acrylonitrile, ethyleneimine, aniline, pyrrole and polyethyleneimine, and salts thereof.
- ethylenediamine and ethylenediamine dihydrochloride are preferable because the activity of the catalyst obtained through the contact step described later is high.
- the nitrogen-containing organic compound (2) is preferably further a hydroxyl group, a carboxyl group, an aldehyde group, an acid halide group, a sulfo group, a phosphoric acid group, a ketone group, an ether group or an ester group (these are collectively referred to as “oxygen-containing molecule”). It is also called a group.)
- oxygen-containing molecule a group that the nitrogen-containing organic compound (2) can be coordinated more strongly with the metal atom derived from the metal compound (1) through mixing in the step (1). .
- the oxygen-containing molecular groups a carboxyl group and an aldehyde group are particularly preferable because the activity of the catalyst obtained through the contact step described later is particularly high.
- the nitrogen-containing organic compound (2) containing an oxygen atom in the molecule the nitrogen-containing molecular group and the compound having the oxygen-containing molecular group are preferable. Such a compound is considered to be able to coordinate particularly strongly to the metal atom derived from the metal compound (1) through the step (1).
- amino acids having an amino group and a carboxyl group, and derivatives thereof are preferable.
- the amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophan, tyrosine, valine, norvaline, glycylglycine, Triglycine and tetraglycine are preferable, and since the activity of the catalyst obtained through the contact step described below is high, alanine, glycine, lysine, methionine, and tyrosine are more preferable, and the catalyst obtained through the contact step described below is extremely Alanine, glycine and lysine are particularly preferred because they exhibit high activity.
- nitrogen-containing organic compound (2) containing an oxygen atom in the molecule examples include acyl pyrroles such as acetyl pyrrole, acyl imidazoles such as pyrrole carboxylic acid and acetyl imidazole, Imidazole, imidazolecarboxylic acid, pyrazole, acetanilide, pyrazinecarboxylic acid, piperidinecarboxylic acid, piperazinecarboxylic acid, morpholine, pyrimidinecarboxylic acid, nicotinic acid, 2-pyridinecarboxylic acid, 2,4-pyridinedicarboxylic acid, 8-quinolinol, and Polyvinyl pyrrolidone, and a compound that can be a bidentate ligand, such as pyrrole-2-carboxylic acid, imidazole-4-carboxylic acid; 2-Pyrazi Carboxylic acid, 2-piperidinecarboxylic acid, 2-piperaz
- the ratio of the total number of carbon atoms B in the nitrogen-containing organic compound (2) used in the step (1) to the total number of metal atoms A in the metal compound (1) used in the step (1) can reduce the amount of components desorbed as carbon compounds such as carbon dioxide and carbon monoxide during the heat treatment in step (3), that is, the amount of exhaust gas can be reduced during the production of the catalyst precursor. Therefore, it is preferably 200 or less, more preferably 150 or less, still more preferably 80 or less, particularly preferably 30 or less, and preferably 1 or more, more preferably 2 or more, from the viewpoint of obtaining a catalyst with good activity. More preferably, it is 3 or more, and particularly preferably 5 or more.
- Ratio of the total number of atoms C of nitrogen of the nitrogen-containing organic compound (2) used in step (1) to the total number of atoms A of the metal elements of the metal compound (1) used in step (1) is preferably 28 or less, more preferably 17 or less, still more preferably 12 or less, particularly preferably 8.5 or less, from the viewpoint of obtaining a catalyst having a good activity through a contact step described later. From the viewpoint of obtaining a catalyst having a good activity through the contacting step, it is preferably 1 or more, more preferably 2.5 or more, still more preferably 3 or more, and particularly preferably 3.5 or more.
- the compound (3) containing fluorine is further mixed (in the chemical structure) to further pass through the contact step described later, thereby further increasing the catalytic activity.
- a catalyst can be produced.
- the compound (3) containing fluorine in the chemical structure
- examples of the compound (3) containing fluorine include alcohols containing fluorine atoms, ethers containing fluorine atoms, amines containing fluorine atoms, carboxylic acids containing fluorine atoms, fluorine Examples thereof include boric acid derivatives containing atoms, phosphoric acid derivatives containing fluorine atoms, and sulfonic acid derivatives containing fluorine atoms.
- Examples of the alcohol containing fluorine atoms and derivatives thereof include: A saturated or unsaturated aliphatic alcohol in which all or part of the hydrogen atoms of the hydrocarbon group are substituted with fluorine atoms (the number of carbon atoms is, for example, 1 to 30), such as nonacosadecafluorotetradecyl alcohol, Heptacosadecafluorotridecyl alcohol, Pentacosa decafluorododecyl alcohol, Henicosa decafluorodecyl alcohol, Heptadecafluorooctyl alcohol, Tridecafluorohexyl alcohol, Nonafluorobutyl alcohol, Pentafluoroethyl alcohol, Trifluoromethyl alcohol, 2,2,2-trifluoroethyl alcohol, 6-perfluorohexyl hexanol, 2,5-di (trifluoromethyl) -3,6-dioxoundecafluor
- the alcohol or derivative thereof containing a fluorine atom preferably has 3 or more fluorine atoms in one molecule.
- the ether containing a fluorine atom is represented by the formula R f —O—R f ′ (R f and R f ′ are each independently a hydrocarbon group in which all or part of the hydrogen atoms are substituted with fluorine atoms.
- R f and R f ′ include nonacosadecafluorotetradecyl group, heptacosadecafluorotridecyl group, pentacosadecafluorododecyl group, tricosadecafluoroundecyl group, henicosadecafluorodecyl group, nona Decafluorononyl group, heptadecafluorooctyl group, pentadecafluoroheptyl group, tridecafluorohexyl group, undecafluoropentyl group, nonafluorobutyl group, heptafluoropropyl group, pentafluoroethyl group, trifluoromethyl group and 2 , 2,2-trifluoroethyl group and the like, and R f and R f ′ may be a group having an aryl group (for example, phenyl group,
- a compound represented by Examples of commercially available products include Novec TM HFE (trade name) (hydrofluoroether, Hishie Chemical Co., Ltd.) and Novec TM HFE (trade name) (hydrofluoroether, 3M).
- ethers containing fluorine atoms As ethers containing fluorine atoms, surflon (registered trademark) S-241, S-242, S-243, S-420 (AGC Seimi Chemical Co., Ltd.), which is a fluorine-containing surfactant, Trademark) 250 (Neos Corporation) may be used.
- the ether or derivative thereof containing a fluorine atom preferably has 3 or more fluorine atoms in one molecule.
- Examples of the amine containing fluorine atoms and derivatives thereof include: R f —NR 1 R 2 (R f is a saturated or unsaturated aliphatic hydrocarbon group in which all or part of the hydrogen atoms are replaced by fluorine atoms, and R 1 and R 2 are each independently Or a saturated or unsaturated aliphatic amine (R) represented by a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms in which all or part of the hydrogen atoms may be substituted with fluorine atoms.
- the number of carbon atoms of f is, for example, 1 to 30.
- nonacosadecafluorotetradecylamine heptacosadecafluorotridecylamine, pentacosadecafluorododecylamine, heikosadecafluorodecylamine, heptadeca Fluorooctylamine, pentadecafluoroheptylamine, undecafluoropentylamine, heptafluoropropylamine, pentafluoroethyl Amine, fluoroalkyl amines such as trifluoromethyl amine and 2,2,2-trifluoroethylamine; A salt of the fluoroalkylamine (general formula: A + [R 4 N] ⁇ ; A + represents, for example, a sodium ion, a potassium ion or an ammonium ion, and each R independently represents a fluoroalkyl
- the amine or derivative thereof containing a fluorine atom preferably has 3 or more fluorine atoms in one molecule.
- Examples of the carboxylic acid containing fluorine atoms and derivatives thereof include: Saturated or unsaturated aliphatic carboxylic acids in which all or part of the hydrogen atoms of the hydrocarbon group are substituted with fluorine atoms (the number of carbon atoms is, for example, 1 to 30), such as nonacosadecafluorotetradecanoic acid, Heptacosadecafluorotridecanoic acid, pentacosadecafluorododecanoic acid, tricosadecafluoroundecanoic acid, henicosadecafluorodecanoic acid, heptadecafluorooctanoic acid, tridecafluorohexanoic acid, nonafluorobutanoic acid, pentafluoroacetic acid , Fluoroalkylcarboxylic acids such as trifluoroacetic acid, 2,2,2-trifluoroethylcarboxylic acid
- a hydrocarbon group having 1 to 10 carbon atoms which may be partially substituted with a fluorine atom (for example, methyl group, ethyl group, phenyl group).
- a fluorine atom for example, methyl group, ethyl group, phenyl group.
- An acid anhydride of the aliphatic carboxylic acid generally formula: (R f —CO) 2 O, R f represents a fluoroalkyl group in the aliphatic carboxylic acid), such as heptadecafluorooctanoic acid anhydride;
- An amino acid for example, an
- the carboxylic acid or derivative thereof containing a fluorine atom preferably has three or more fluorine atoms in one molecule.
- Tetrafluoroborate quaternary ammonium salts eg, tetra-n-butylammonium tetrafluoroborate, tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, ethyl tetrafluoroborate Trimethylammonium, diethyldimethylammonium tetrafluoroborate, triethylmethylammonium tetrafluoroborate, methyltripropylammonium tetrafluoroborate, trimethylpropylammonium tetrafluoroborate, ethyldimethylpropylammonium tetrafluoroborate, triethyltetrafluoroborate Propyl ammonium, dimethyldipropyl ammonium
- boric acid derivative containing fluorine preferably, ammonium tetrafluoroborate, methylammonium tetrafluoroborate, dimethylammonium tetrafluoroborate, trimethylammonium tetrafluoroborate, ethylammonium tetrafluoroborate, tetrafluoroborate Diethylammonium acid, triethylammonium tetrafluoroborate, butylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, tetrapropyltetrafluoroborate Ammonium, tetrabutylammonium tetrafluoroborate, tetrafluoroboric acid-1-butyl-3-methylimida Zolium is
- Hexafluorophosphates such as hexafluorophosphate quaternary ammonium salts (eg tetra-n-butylammonium hexafluorophosphate, tetramethylammonium hexafluorophosphate, tetraethylammonium hexafluorophosphate, tetrahexafluorophosphate)
- hexafluorophosphate quaternary ammonium salts eg tetra-n-butylammonium hexafluorophosphate, tetramethylammonium hexafluorophosphate, tetraethylammonium hexafluorophosphate, tetrahexafluorophosphate
- Propylammonium ethyltrimethylammonium hexafluorophosphate, diethyldimethylammonium hexafluorophosphate, trie
- Fluoroalkyl phosphoric acid amide A fluoroalkylphosphorous acid represented by the general formula (RO) 3 P, (RO) 2 (OH) P, or (RO) (OH) 2 P (wherein the above-mentioned fluoroalkyl group is represented), A fluoroalkyl phosphite amide represented by the general formula (RN) 3 P, (RN) 2 P (OH), (RN) P (OH) 2 (wherein R represents the fluoroalkyl group), Examples thereof include fluoroalkylphosphonic acids represented by the general formula: RPO (OH) 2 (wherein R represents the fluoroalkyl group).
- the phosphoric acid derivative containing fluorine is preferably ammonium hexafluorophosphate, methylammonium hexafluorophosphate, dimethylammonium hexafluorophosphate, trimethylammonium hexafluorophosphate, ethylammonium hexafluorophosphate, hexafluorophosphoric acid Diethylammonium, triethylammonium hexafluorophosphate, butylammonium hexafluorophosphate, dibutylammonium hexafluorophosphate, tetra-n-butylammonium hexafluorophosphate, tetramethylammonium hexafluorophosphate, tetraethylammonium hexafluorophosphate, And tetrabutylammonium hexafluorophosphate, and more preferably ammonium hexaflu
- a copolymer of tetrafluoroethylene and perfluoro [2- (fluorosulfonylethoxy) propyl vinyl ether] for example, NAFION (registered trademark), a copolymer having a structure represented by the following formula)
- Fluoroalkylsulfonic acid in which all or part of the hydrogen atoms of the alkyl group are substituted with fluorine atoms (for example, nonacosadecafluorotetradecanesulfonic acid, heptacosadecafluoro Tridecanesulfonic acid, tricosadecafluoroundecanesulfonic acid, nonadecafluorononanesulfonic acid, pentadecafluoroheptanesulfonic acid, undecafluoropentanesulfonic acid, nonafluorobutanesulfonic acid, heptafluoropropanesulfonic acid, trifluoromethanesulfonic acid And 2,2,2-trifluoroethanesulfonic acid), Esters of the fluoroalkylsulfonic acid (for example, methyl ester, ethyl ester, aryl
- the fluorine-containing sulfonic acid derivative is preferably a copolymer of tetrafluoroethylene and perfluoro [2- (fluorosulfonylethoxy) propyl vinyl ether] (for example, NAFION (registered trademark)), hepta Decafluorooctanesulfonic acid, pentadecafluoroheptanesulfonic acid, undecafluoropentanesulfonic acid, heptafluoropropanesulfonic acid, trifluoromethanesulfonic acid, ammonium heptadecafluorooctanesulfonate, ammonium pentadecafluoroheptanesulfonate, tridecafluoro Ammonium hexanesulfonate, ammonium nonafluorobutanesulfonate, ammonium pentafluoroethanesulfonate, ammonium trifluoromethanesulf
- the amount of the element A contained in the compound (3) used in the step (1) ( That is, the total number of atoms of the element A contained in the compound (3) used in the step (1)) is usually relative to 1 mol of the metal atom in the metal compound (1) used in the step (1).
- the amount is 0.01 to 3 mol, preferably 0.01 to 2 mol, more preferably 0.01 to 1 mol.
- the amount is usually 0.01 to 3 mol, preferably 0.01 to 2 mol, more preferably 0.01 to 1 mol, based on the above criteria, and element A is phosphorus.
- the amount is usually 0.01 to 3 mol, preferably 0.01 to 2 mol, more preferably 0.01 to 1 mol, based on the above criteria, and when element A is only sulfur.
- the amount is usually 0.01 to 3 mol, preferably 0.01 to 2 mol, more preferably 0.01 to 1 mol, based on the above criteria.
- the amount of fluorine contained in the compound (3) used in the step (1) (that is, the total number of fluorine atoms contained in the compound (3) used in the step (1)) is used in the step (1).
- the amount is usually 0.01 to 5 mol, preferably 0.02 to 4 mol, more preferably 0.03 to 3 mol, relative to 1 mol of the metal atom in the metal compound (1).
- the amount of the compound (3) is an amount when the raw materials other than the compound (3) used in the step (1) do not contain the element A or fluorine, and the raw materials other than the compound (3) are the element A or In the case of containing fluorine, it is preferable to appropriately reduce the amount of the compound (3) used in the step (1).
- solvent examples include water, alcohols and acids.
- alcohols examples include ethanol, methanol, butanol, propanol and ethoxyethanol are preferable, and ethanol and methanol are more preferable.
- acids acetic acid, nitric acid (aqueous solution), hydrochloric acid, phosphoric acid aqueous solution and citric acid aqueous solution are preferable, and acetic acid and nitric acid are more preferable. These may be used alone or in combination of two or more.
- the solvent when the metal compound (1) is a metal halide methanol is preferable.
- the solvent may be used in an amount of 50 to 95% by mass in 100% by mass of the precursor production solution.
- Precipitation inhibitor> When the metal compound (1) contains a halogen atom, these compounds are generally easily hydrolyzed by water, and precipitates such as hydroxides and acid chlorides are easily generated. Therefore, when the metal compound (1) contains a halogen atom, it is preferable to add a strong acid in the solution (precursor production solution) in an amount of 1% by mass or more.
- a strong acid in the solution (precursor production solution) in an amount of 1% by mass or more.
- the acid is hydrochloric acid
- the acid when the acid is added so that the concentration of hydrogen chloride in the solution (precursor production solution) is 5% by mass or more, more preferably 10% by mass or more
- the metal compound (1) A clear precursor-producing solution can be obtained while suppressing the generation of precipitates such as hydroxides, acid chlorides, and the like derived from.
- the precipitation inhibitor is preferably a compound having a diketone structure, more preferably diacetyl, acetylacetone, 2,5-hexanedione and dimedone, and further preferably acetylacetone and 2,5-hexanedione.
- These precipitation inhibitors are preferably 1 to 70% by mass in 100% by mass of a metal compound solution (a solution containing the metal compound (1) and not containing the nitrogen-containing organic compound (2) and the compound (3)). %, More preferably 2 to 50% by mass, still more preferably 15 to 40% by mass.
- precipitation inhibitors are preferably used in an amount of 0.1 to 40% by mass, more preferably 0.5 to 20% by mass, and further preferably 2 to 10% by mass in 100% by mass of the precursor production solution. Is added.
- the precipitation inhibitor may be added at any stage in the step (1).
- step (1) preferably, a solution containing the metal compound (1) and the precipitation inhibitor is prepared, and then the solution, the nitrogen-containing organic compound (2) and optionally the compound (3) are combined. Mixing to obtain a precursor production solution.
- the step (1) is performed, the occurrence of the precipitation can be suppressed more reliably.
- step (2) the solvent is removed from the precursor production solution obtained in step (1).
- the removal of the solvent may be performed in the air or in an inert gas (for example, nitrogen, argon, helium) atmosphere.
- an inert gas for example, nitrogen, argon, helium
- nitrogen and argon are preferable from the viewpoint of cost, and nitrogen is more preferable.
- the temperature at the time of solvent removal may be room temperature when the vapor pressure of the solvent is high, but from the viewpoint of mass productivity of the catalyst precursor, it is preferably 30 ° C or higher, more preferably 40 ° C or higher, Preferably, the temperature is 50 ° C. or higher, and is preferably 350 ° C. or lower, more preferably from the viewpoint of not decomposing a substance presumed to be a metal complex such as a chelate contained in the solution obtained in step (1). It is 150 degrees C or less, More preferably, it is 110 degrees C or less.
- the removal of the solvent may be performed under atmospheric pressure when the vapor pressure of the solvent is high, but in order to remove the solvent in a shorter time, it is performed under reduced pressure (for example, 0.1 Pa to 0.1 MPa). Also good.
- reduced pressure for example, 0.1 Pa to 0.1 MPa.
- an evaporator can be used to remove the solvent under reduced pressure.
- the solvent may be removed while the mixture obtained in the step (1) is left standing, but in order to obtain a more uniform solid residue, it is preferable to remove the solvent while rotating the mixture. .
- the composition or aggregation state of the solid residue obtained in the step (2) may be different. May be non-uniform. In such a case, if a solid residue is mixed and crushed to obtain a more uniform and fine powder in step (3), a catalyst precursor having a more uniform particle size can be obtained. it can.
- solid residue for example, roll rolling mill, ball mill, small diameter ball mill (bead mill), medium stirring mill, airflow crusher, mortar, automatic kneading mortar, tank crusher, jet mill If the solid residue is small, preferably, a mortar, an automatic kneading mortar, or a batch type ball mill is used, and when the solid residue is large and continuous mixing and crushing are performed.
- a jet mill is preferably used.
- step (3) the solid residue obtained in step (2) is heat-treated to obtain a catalyst precursor.
- the temperature during this heat treatment is preferably 500 to 1100 ° C., more preferably 600 to 1050 ° C., and still more preferably 700 to 950 ° C.
- Examples of the heat treatment method include a stationary method, a stirring method, a dropping method, and a powder trapping method.
- the stationary method is a method in which the solid residue obtained in step (2) is placed in a stationary electric furnace or the like and heated.
- the solid content residue weighed during heating may be put in a ceramic container such as an alumina board or a quartz board.
- the stationary method is preferable in that a large amount of the solid residue can be heated.
- the stirring method is a method in which the solid residue is placed in an electric furnace such as a rotary kiln and heated while stirring.
- the stirring method is preferable in that a large amount of the solid residue can be heated and aggregation and growth of the obtained catalyst precursor particles can be suppressed.
- the stirring method is preferable in that the catalyst precursor can be continuously produced by inclining the heating furnace.
- the dropping method an atmospheric gas is passed through an induction furnace, the furnace is heated to a predetermined heating temperature, and after maintaining a thermal equilibrium at the temperature, the solid residue is placed in a crucible that is a heating area of the furnace. It is a method of dropping and heating this.
- the dropping method is preferable in that aggregation and growth of the obtained catalyst precursor particles can be suppressed to a minimum.
- Powder capture method is an inert gas atmosphere containing a small amount of oxygen gas, the solid residue is splashed and suspended, captured in a vertical tube furnace maintained at a predetermined heating temperature, It is a method of heating.
- the rate of temperature rise is not particularly limited, but is preferably about 1 ° C./min to 100 ° C./min, more preferably 5 ° C./min to 50 ° C./min. is there.
- the heating time is preferably 0.1 to 10 hours, more preferably 0.5 hours to 5 hours, and further preferably 0.5 to 3 hours.
- the heating time for the solid residue is 0.1 to 10 hours, preferably 0.5 to 5 hours.
- the heating time of the solid residue is usually 10 minutes to 5 hours, preferably 30 minutes to 2 hours.
- the average residence time calculated from the steady sample flow rate in the furnace is set as the heating time.
- the heating time of the solid residue is usually 0.5 to 10 minutes, preferably 0.5 to 3 minutes.
- the heating time is within the above range, uniform catalyst precursor particles tend to be formed.
- the heating time of the solid residue is 0.2 seconds to 1 minute, preferably 0.2 to 10 seconds.
- the heating time is within the above range, uniform catalyst precursor particles tend to be formed.
- a heating furnace using LNG (liquefied natural gas), LPG (liquefied petroleum gas), light oil, heavy oil, electricity or the like as a heat source may be used as the heat treatment apparatus.
- LNG liquefied natural gas
- LPG liquefied petroleum gas
- light oil a heating furnace using LNG (liquefied natural gas), LPG (liquefied petroleum gas), light oil, heavy oil, electricity or the like as a heat source
- the fuel flame is present in the furnace, and is not heated from the inside of the furnace, but is heated from the outside of the furnace.
- An apparatus is preferred.
- a heating furnace using LNG and LPG as a heat source is preferable from the viewpoint of cost.
- LNG and LPG as a heat source
- Examples of the shape of the furnace include a tubular furnace, a top lid furnace, a tunnel furnace, a box furnace, a sample table raising / lowering furnace (elevator type), a cart furnace, and the like, and the atmosphere can be controlled particularly strictly.
- Tubular furnaces, top lid furnaces, box furnaces and sample table raising / lowering furnaces are preferred, and tubular furnaces and box furnaces are preferred.
- the above heat source can be used.
- a heat source derived from a fuel such as LPG because the amount of energy used tends to increase.
- the atmosphere for performing the heat treatment is preferably an atmosphere whose main component is an inert gas from the viewpoint of enhancing the activity of the electrode catalyst obtained through the contact step described later.
- inert gases nitrogen, argon, and helium are preferable and nitrogen and argon are more preferable because they are relatively inexpensive and easily available.
- These inert gas may be used individually by 1 type, and may mix and use 2 or more types.
- These gases are generally called inert gases, but these inert gases, that is, nitrogen, argon, helium, and the like during the heat treatment in the step (3) are separated from the solid residue. It may be reacting.
- an electrode catalyst obtained through a contact process described later may exhibit higher catalytic performance.
- the heat treatment is performed using nitrogen gas, argon gas, a mixed gas of nitrogen gas and argon gas, or one or more gases selected from nitrogen gas and argon gas, and one or more selected from hydrogen gas, ammonia gas, and oxygen gas.
- an electrode catalyst having high catalytic performance tends to be obtained through a contact step described later.
- the hydrogen gas concentration is, for example, 100% by volume or less, preferably 0.01 to 10% by volume, more preferably 1 to 5% by volume.
- the concentration of oxygen gas is, for example, 0.01 to 10% by volume, preferably 0.01 to 5% by volume.
- the pressure during the heat treatment is not particularly limited, and the heat treatment may be performed under atmospheric pressure in consideration of production stability and cost.
- the heat treatment product may be crushed.
- pulverization it may be possible to improve the processability when producing an electrode using an electrode catalyst obtained through a contact step described later, and the characteristics of the obtained electrode.
- a roll rolling mill for example, a ball mill, a small-diameter ball mill (bead mill), a medium stirring mill, an airflow grinder, a mortar, an automatic kneading mortar, a tank disintegrator, or a jet mill can be used.
- the catalyst precursor is a small amount
- a mortar, an automatic kneading mortar, and a batch type ball mill are preferable.
- a heat treated product is continuously processed in a large amount, a jet mill and a continuous ball mill are preferable, and a continuous type is used.
- a bead mill is more preferable.
- a production method that does not use a solvent in the production method (A) of the catalyst precursor that is, a mixture containing at least the metal compound (1) and the nitrogen-containing organic compound (2) and no solvent (preferably 500 to 1100 ° C.
- a part of or all of the metal compound (1) contains copper, and at least one of the components contained in the mixture has an oxygen atom.
- a catalyst precursor produced by a production method and a step of heat-treating copper as a metal element and optionally iron or a metal carbonitride containing the metal element (M3) in an inert gas containing oxygen
- the catalyst precursor manufactured by the manufacturing method (henceforth "the manufacturing method (B) of a catalyst precursor") is mentioned.
- a mixture containing a compound containing copper and optionally a compound containing iron or the compound containing the metal M3 is heat-treated (however, any of these compounds and the heat treatment atmosphere contains carbon and nitrogen).
- the heat treatment temperature of the metal carbonitride is usually 400 to 1400 ° C., preferably 600 to 1200 ° C.
- the temperature for producing the metal carbonitride is usually 600 to 1800 ° C., preferably 800 to 1600. ° C.
- a conventionally known fuel cell electrode catalyst containing each atom of a metal element, carbon, nitrogen and oxygen and containing copper as the metal element may be used as the catalyst precursor.
- the catalyst precursor is preferably crushed before being subjected to the next contact step.
- a fuel cell electrode catalyst is obtained by bringing the catalyst precursor into contact with an acidic solution.
- Examples of the acid include hydrogen chloride, sulfuric acid, citric acid, acetic acid, hydrofluoric acid, phosphoric acid, and nitric acid, and hydrogen chloride, sulfuric acid, citric acid, acetic acid, nitric acid, and phosphoric acid are preferable. These can be used individually by 1 type or in combination of 2 or more types.
- a hydrophilic solvent is preferable, a compound having a hydroxyl group, a compound having an ether bond, and water are more preferable, an alcohol such as methanol, ethanol, propanol, isopropanol, and butanol, and a cyclic ether such as THF (tetrahydrofuran). And water are more preferable, and water is particularly preferable. These can be used individually by 1 type or in combination of 2 or more types.
- the concentration of the acid in the acidic solution is preferably 0.01 to 15N, more preferably 0.5 to 13N, and still more preferably 1 to 13N at 25 ° C. It is preferable that the acid concentration is in the above-mentioned range because the copper in the catalyst precursor is easily dissolved uniformly.
- the temperature in the contact step (hereinafter also referred to as “contact temperature”) is preferably 15 to 100 ° C., more preferably 20 to 80 ° C., and further preferably 25 to 70 ° C.
- contact temperature is within the above range, it is preferable in that the copper in the catalyst precursor dissolves quickly and the acidic solution hardly evaporates.
- the time for the contact step (hereinafter also referred to as “contact time”) is preferably 0.1 to 500 hours, more preferably 5 to 300 hours, and further preferably 6 to 150 hours.
- contact time is preferably 0.1 to 500 hours, more preferably 5 to 300 hours, and further preferably 6 to 150 hours.
- contact time is within the above range, it is preferable in that the dissolution of copper in the catalyst precursor proceeds uniformly.
- the catalyst precursor and the acidic solution are brought into contact with each other by charging them into a container. At this time, it is preferable to perform stirring.
- the ratio of the catalyst precursor to the acidic solution depends on the type of the catalyst precursor, but as a guideline, the acidic solution is preferably 10 to 50000 mL, more preferably 1 g of the catalyst precursor. Is 30-10000 mL.
- Part of the metal element in the catalyst precursor is eluted by bringing the catalyst precursor into contact with the acidic solution.
- the metal element in the catalyst precursor For example, 50% or more, more preferably 90% or more of the copper contained in the catalyst precursor before elution is eluted.
- all the copper may be eluted as long as an element other than copper remains in the catalyst precursor.
- the elution amount of the metal element tends to increase, for example, when the acid concentration is increased, the contact temperature is increased, or the contact time is increased.
- the contact step is completed by collecting the solid content obtained through the contact step (hereinafter also referred to as “contact treated product”).
- Examples of the means for recovering the contact treated product include known techniques such as suction filtration and centrifugation.
- the production method of the present invention preferably includes a cleaning step of cleaning the contact treated product after the contacting step.
- the cleaning step By providing the cleaning step, the eluted metal component that causes the electrolyte membrane deterioration can be further removed from the contact treated product after the contact step.
- the cleaning step is performed, for example, by bringing the cleaning liquid and the contact-treated product into a container and bringing them into contact with each other. At this time, it is preferable to perform stirring.
- the production method of the present invention preferably includes a drying step of drying the contact treated product after the contacting step, and more preferably includes a drying step in the washing step.
- drying in the drying step examples include vacuum drying (reduced pressure drying) and heat drying.
- the drying step is preferably performed at a temperature of 100 ° C. or less from the viewpoint of preventing aggregation of the contact processed product.
- the fuel cell electrode catalyst according to the present invention is a catalyst produced by the production method according to the present invention.
- the fuel cell electrode catalyst is preferably a powder in order to enhance catalytic ability.
- the fuel cell electrode catalyst can be used as an alternative catalyst for a platinum catalyst.
- the specific surface area calculated by the BET method of the catalyst of the present invention is preferably 50 m 2 / g or more. More preferably, it is 100 to 1200 m 2 / g, and still more preferably 200 to 900 m 2 / g.
- This specific surface area can be increased as, for example, more metal element in the catalyst precursor is removed in the contact step.
- the fuel cell electrode catalyst layer according to the present invention includes the fuel cell electrode catalyst.
- the fuel cell electrode catalyst layer preferably further contains an electron conductive powder.
- the reduction current can be further increased.
- the electron conductive powder is considered to increase the reduction current because it causes an electrical contact for inducing an electrochemical reaction in the catalyst.
- the electron conductive particles are usually used as a catalyst carrier.
- the fuel cell electrode catalyst layer preferably further includes a polymer electrolyte.
- the polymer electrolyte is not particularly limited as long as it is generally used in a fuel cell electrode catalyst layer.
- the fuel cell electrode catalyst layer can be used as either an anode catalyst layer or a cathode catalyst layer.
- the fuel cell electrode catalyst layer has a high oxygen reduction ability and contains a catalyst that does not corrode even in a high potential in an acidic electrolyte. Therefore, a catalyst layer (cathode catalyst layer provided on the cathode of a fuel cell) ) And is particularly useful as a catalyst layer provided on the cathode of the membrane electrode assembly provided in the polymer electrolyte fuel cell.
- the electrode according to the present invention is characterized by having the fuel cell electrode catalyst layer and a porous support layer.
- the electrode can be used as either a cathode or an anode. Since the electrode is excellent in durability and has a large catalytic ability, it is more effective when used as a cathode.
- the membrane / electrode assembly (hereinafter also referred to as “MEA”) of the present invention is a membrane / electrode assembly having a cathode, an anode, and an electrolyte membrane disposed between the cathode and the anode.
- the anode is the electrode according to the present invention.
- the electrode according to the present invention is used as the cathode.
- a conventionally known fuel cell electrode for example, an electrode containing a platinum-based catalyst may be used as the anode.
- an electrolyte membrane using a perfluorosulfonic acid system or a hydrocarbon electrolyte membrane is generally used.
- a membrane or porous body in which a polymer microporous membrane is impregnated with a liquid electrolyte is used.
- a membrane filled with a polymer electrolyte may be used.
- the cell voltage of the membrane electrode assembly (“cell voltage 20 hours after the start of operation” (catalytic activity) in “evaluation of catalytic ability and durability of membrane electrode assembly” described later)
- the cell voltage of the membrane / electrode assembly which was prepared by changing the catalyst to the catalyst precursor used in the production of the catalyst, was preferably 50 mV or more, more preferably 80 mV or more, and even more preferably 100 mV or more. it can.
- the “gradient of voltage drop” (catalyst durability)) is preferably 6 mV / hour or less, more preferably 3 mV / hour or less, and even more preferably 1.5 mV / hour or less.
- the fuel cell according to the present invention includes the membrane electrode assembly. Fuel cell electrode reactions occur at the so-called three-phase interface (electrolyte-electrode catalyst-reaction gas). Fuel cells are classified into several types depending on the electrolyte used, etc., and include molten carbonate type (MCFC), phosphoric acid type (PAFC), solid oxide type (SOFC), and solid polymer type (PEFC). . As the fuel cell according to the present invention, a polymer electrolyte fuel cell is preferable.
- Combustion decomposition conditions Sample combustion apparatus: AQF-100 (Mitsubishi Chemical Analytech Co., Ltd.) Combustion tube temperature: 950 ° C (temperature decomposition by moving the sample board) Ion chromatography measurement conditions Measuring device: DIONEX DX-500 Eluent: 1.8 mM Na 2 CO 3 +1.7 mM NaHCO 3 Column (temperature): ShodexSI-90 (room temperature) Flow rate: 1.0 ml / min Injection volume: 25 ⁇ l Detector: Electrical conductivity detector Suppressor: DIONEX ASRS-300 2. BET specific surface area measurement; The BET specific surface area was measured using Micromeritics Gemini 2360 manufactured by Shimadzu Corporation. The pretreatment time and pretreatment temperature were set at 30 ° C. and 200 ° C., respectively.
- the soaked material was dried at room temperature and then heated at 350 ° C. for 1 hour to obtain a gas diffusion layer (hereinafter also referred to as “GDL”) having PTFE dispersed within the carbon paper and having water repellency.
- GDL gas diffusion layer
- the anode ink was applied to the surface of the GDL having a size of 5 cm ⁇ 5 cm at 80 ° C. by an automatic spray coating apparatus (manufactured by Sanei Tech Co., Ltd.).
- an electrode hereinafter also simply referred to as “anode” having an anode catalyst layer having a platinum (Pt) amount of 1 mg / cm 2 per unit area was produced.
- GDL gas diffusion layer
- cathode an electrode having a cathode catalyst layer on the GDL surface
- the MEA is fixed in place with two bolts by sequentially sandwiching the MEA with two sealing materials (gaskets), two separators with gas flow paths, two current collector plates and two rubber heaters.
- a single cell (cell area: 5 cm 2 ) of a polymer electrolyte fuel cell was produced by tightening to a surface pressure (4N).
- stage a a stage in which sudden voltage fluctuation occurs once after the start of continuous operation
- stage b a transition stage in which voltage fluctuation suddenly decreases after stage a
- stage c the stage after the stage b became almost constant when the voltage fluctuation was small. In many cases, the process shifts to step c in about 5 hours from the start of operation.
- the cell voltage 20 hours after the start of operation after the transition to the stage c was measured, and the higher the value, the higher the catalytic ability was evaluated.
- the cell voltage plot in the portion where the time change of the cell voltage is relatively small (between 5 hours and 20 hours after the start of continuous operation) among the portions after the transition to the step c is linearized by the least square method. The smaller the absolute value of the slope of the approximate straight line obtained (that is, the voltage drop per unit time, also referred to as “the slope of the voltage drop”), the higher the catalyst durability.
- the measurement time may be sequentially postponed until the process proceeds to the stage c.
- the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and while stirring the mixture (1), the solvent was slowly evaporated, and the resulting solid residue was further treated with nitrogen.
- the mixture was heated at 300 ° C. for 1 hour under an air stream, allowed to cool to room temperature, and ground in an automatic mortar for 30 minutes to obtain 3.47 g of powder for firing (1).
- the single cell was created by the procedure mentioned above using the said catalyst (c1), and the evaluation was performed.
- the total mass (mass per unit area) of the catalyst (c1) and carbon black is 2.5 mg / cm 2
- the mass (mass per unit area) of the catalyst (c1) is 2.27 mg / cm 2 .
- Example 1 The evaluation results of the catalyst (c1) are shown in Table 1. [Example 1] 1. Preparation of fuel cell electrode catalyst; A catalyst precursor (1) was produced in the same manner as in Comparative Example 1 except that the amount of each raw material was quadrupled.
- the single cell was created by the procedure mentioned above using the said catalyst (1), and the evaluation was performed.
- the total mass (mass per unit area) of the catalyst (1) and carbon black is 2.5 mg / cm 2
- the mass (mass per unit area) of the catalyst (1) is 2.06 mg / cm 2 .
- the temperature of the hot stirrer was set to about 100 ° C. under reduced pressure in a nitrogen atmosphere, and while stirring the mixture (2), the solvent was slowly evaporated, and the resulting solid residue was further treated with nitrogen.
- the mixture was heated at 300 ° C. for 1 hour under an air stream, allowed to cool to room temperature, and ground in an automatic mortar for 30 minutes to obtain 16.1 g of powder for firing (2).
- the single cell was created by the procedure mentioned above using the said catalyst (c2), and the evaluation was performed.
- the evaluation results of the catalyst (c2) are shown in Table 1.
- a catalyst precursor (2) was produced in the same manner as in Comparative Example 2 except that the amount of each raw material was quadrupled.
- the single cell was created by the procedure mentioned above using the said catalyst (c3), and the evaluation was performed.
- the evaluation results of the catalyst (c3) are shown in Table 1.
- Example 3 A catalyst precursor (3) was produced in the same manner as in Comparative Example 3 except that the amount of each raw material was quadrupled.
- Example 1 Except that the catalyst precursor (1) was changed to 1479 mg of the catalyst precursor (3) and the amount of concentrated hydrochloric acid was changed to 53 ml, the same operation as in Example 1 was carried out to produce 418 mg of the catalyst (3). .
- the single cell was created by the procedure mentioned above using the said catalyst (c4), and the evaluation was performed.
- the evaluation results of the catalyst precursor (c4) are shown in Table 1.
- Example 4 A catalyst precursor (4) was produced in the same manner as in Comparative Example 4 except that the amount of each raw material was doubled.
- Example 1 Except that the catalyst precursor (1) was changed to 735 mg of the catalyst precursor (4) and the amount of concentrated hydrochloric acid was changed to 26 ml, the same operation as in Example 1 was carried out to produce 341 mg of the catalyst (4). .
- the evaluation results of the catalyst (4) are shown in Table 1.
- a single cell was prepared by the above-described procedure using the catalyst (c5) and evaluated.
- the evaluation results of the catalyst (c5) are shown in Table 1.
- Example 5 A catalyst precursor (5) was produced in the same manner as in Comparative Example 5 except that the amount of each raw material was tripled.
- Example 1 Except that the catalyst precursor (1) was changed to 1100 mg of the catalyst precursor (5) and the amount of concentrated hydrochloric acid was changed to 40 ml, the same operation as in Example 1 was carried out to produce 611 mg of the catalyst (5). .
- the single cell was created by the procedure mentioned above using the said catalyst (c6), and the evaluation was performed.
- the evaluation results of the catalyst (c6) are shown in Table 1.
- Example 6 A catalyst precursor (6) was produced in the same manner as in Comparative Example 6. Except that the catalyst precursor (1) was changed to 834 mg of the catalyst precursor (6) and the amount of concentrated hydrochloric acid was changed to 30 ml, the same operation as in Example 1 was carried out to produce 516 mg of the catalyst (6). .
- the single cell was created by the procedure mentioned above using the said catalyst (6), and the evaluation was performed.
- the evaluation results of the catalyst (6) are shown in Table 1.
- the single cell was created by the procedure mentioned above using the said catalyst (c7), and the evaluation was performed.
- the evaluation results of the catalyst (c7) are shown in Table 1.
- a zirconium solution (4) was prepared in the same manner as in Comparative Example 4. In a beaker, 200 ml of water, 160 ml of ethanol, and 200 ml of acetic acid were added, and while stirring these, 11.98 g (96.0 mmol) of pyrazinecarboxylic acid, 5 ml of NAFION (NAFION®) solution (DE521, DuPont) 5 ml And 44 mg (0.251 mmol) of iron (II) acetate was added in small portions and dissolved over about 10 minutes. Next, while maintaining the temperature at room temperature and stirring, the above zirconium solution (4) was added dropwise over 10 minutes to obtain a solution (c8).
- NAFION NAFION
- II iron
- the single cell was created by the procedure mentioned above using the said catalyst (c8), and the evaluation was performed.
- the evaluation results of the catalyst (c8) are shown in Table 1.
- the single cell of Example 3 has a composition almost equivalent to that of the catalyst (3), and compared with Comparative Example 7 using the catalyst (c7) obtained without passing through the contact step, 20 hours after the start of operation.
- the cell voltage was high and the slope of the voltage drop was small. The same result was obtained when Example 4 and Comparative Example 8 were compared.
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Abstract
Description
[1]
金属元素、炭素、窒素および酸素の各原子を含み、前記金属元素として銅を含む触媒前駆体を準備する工程、および
前記触媒前駆体と酸性溶液とを接触させて触媒を得る接触工程
を含む、燃料電池用電極触媒の製造方法。
前記金属元素の10~99モル%が銅である上記[1]に記載の燃料電池用電極触媒の製造方法。
前記金属元素として鉄をさらに含む上記[1]または[2]に記載の燃料電池用電極触媒の製造方法。
前記金属元素の1~20モル%が鉄である上記[3]に記載の燃料電池用電極触媒の製造方法。
前記金属元素としてナトリウム、チタン、ジルコニウム、亜鉛およびタンタルからなる群から選ばれる少なくとも1種をさらに含む上記[1]~[4]のいずれかに記載の燃料電池用電極触媒の製造方法。
前記酸性溶液が塩化水素、硫酸、クエン酸および酢酸から選ばれる少なくとも1種の酸の水溶液である上記[1]~[5]に記載の燃料電池用電極触媒の製造方法。
前記接触工程を下記条件で行う上記[1]~[6]のいずれかに記載の燃料電池用電極触媒の製造方法。
時間:0.1~500時間
酸の濃度:0.01~15N
[8]
上記[1]~[7]のいずれかに記載の製造方法により製造される燃料電池用電極触媒。
上記[8]に記載の燃料電池用電極触媒を含む燃料電池用電極触媒層。
[10]
燃料電池用電極触媒層と多孔質支持層とを有する電極であって、前記燃料電池用電極触媒層が上記[9]に記載の燃料電池用電極触媒層である電極。
カソードとアノードと前記カソードおよび前記アノードの間に配置された電解質膜とを有する膜電極接合体であって、前記カソードおよび/または前記アノードが上記[10]に記載の電極である膜電極接合体。
上記[11]に記載の膜電極接合体を備える燃料電池。
[13]
固体高分子型燃料電池である上記[12]に記載の燃料電池。
本発明に係る燃料電池用電極触媒の製造方法は、
金属元素、炭素、窒素および酸素の各原子を含み、前記金属元素として銅を含む触媒前駆体を準備する工程、および
前記触媒前駆体と酸性溶液とを接触させて触媒を得る接触工程
を含むことを特徴としている。なお本明細書において、原子およびイオンを、厳密に区別することなく「原子」と記載する。
触媒前駆体を準備する工程においては、金属元素、炭素、窒素および酸素の各原子を含み、前記金属元素として銅を含む触媒前駆体を準備する。
少なくとも金属化合物(1)と、窒素含有有機化合物(2)と、溶媒とを混合して溶液(以下「前駆体製造用溶液」ともいう。)を得る工程(1)、
前記前駆体製造用溶液から溶媒を除去する工程(2)、および
工程(2)で得られた固形分残渣を(好ましくは500~1100℃の温度で)熱処理して触媒前駆体を得る工程(3)
を含み、
前記金属化合物(1)の一部または全部が、銅を含有し、
前記工程(1)で用いられる成分のうち溶媒以外の少なくとも1つの成分が酸素原子を有する(すなわち、後述する化合物(3)を用いる場合には、化合物(1)、化合物(2)および化合物(3)の少なくとも1つが酸素原子を有し、化合物(3)を用いない場合には、化合物(1)および化合物(2)の少なくとも1つが酸素原子を有する)製造方法(以下「触媒前駆体の製造方法(A)」ともいう。)
により製造される触媒前駆体が挙げられる。
(工程(1))
工程(1)では、少なくとも金属化合物(1)と、窒素含有有機化合物(2)と、溶媒と、任意に後述する化合物(3)を混合して前駆体製造用溶液を得る。
手順(i):1つの容器に溶媒を準備し、そこへ前記金属化合物(1)、前記窒素含有有機化合物(2)および任意に前記化合物(3)を添加し、溶解させて、これらを混合する、
手順(ii):前記金属化合物(1)の溶液、ならびに前記窒素含有有機化合物(2)および任意に前記化合物(3)の溶液を準備し、これらを混合する
が挙げられる。
複数の溶液を調製してからこれらを混合して前駆体製造用溶液を得る場合には、一方の溶液に対して他方の溶液を、ポンプ等を用いて一定の速度で供給することが好ましい。
前記金属化合物(1)の一部または全部は、銅を含んでいる。
また前記金属化合物(1)は、好ましくは鉄を含み、またナトリウム、チタン、ジルコニウム、亜鉛およびタンタルからなる群から選ばれる少なくとも1種の金属元素(M3)を含んでいてもよい。
前記金属化合物(1)のうち、銅を含む化合物の具体例としては、
銅(II)エトキシド、銅(II)イソプロポキシド、銅(II)ブトキシド、銅(II)ペントキシド、銅(II)アセチルアセトナート、ビスジエチルアミノ銅、ビス(2,2,6,6-テトラメチル-3,5-ヘプタンジオン)銅、銅(II)ヘキサフルオロアセチルアセトナート、ビス-1-メトキシ-2-メチル-2-プロポキシ銅(II)、二塩化銅、オキシ塩化銅、二臭化銅、オキシ臭化銅、二ヨウ化銅、オキシヨウ化銅等の銅化合物が挙げられる。これらの化合物は1種単独で用いてもよく2種以上を併用してもよい。
二塩化銅、オキシ塩化銅、銅(II)エトキシド、銅(II)イソプロポキシド、銅(II)ブトキシド、銅(II)アセチルアセトナートが好ましく、
二塩化銅、オキシ塩化銅、銅(II)エトキシド、銅(II)イソプロポキシド、銅(II)アセチルアセトナートがさらに好ましい。
鉄(III)エトキシド、鉄(III)イソプロポキシド、鉄(III)ブトキシド、鉄(III)ペントキシド、鉄(III)アセチルアセトナート、鉄(III)イソプロポキシドアセチルアセトナート(Fe(acac)(O-iPr)2、Fe(acac)2(O-iPr))、トリスジエチルアミノ鉄、トリス(2,2,6,6-テトラメチル-3,5-ヘプタンジオン)鉄、鉄(III)ヘキサフルオロアセチルアセトナート、トリ-1-メトキシ-2-メチル-2-プロポキシ鉄(III)、三塩化鉄、二塩化鉄、オキシ塩化鉄、三臭化鉄、二臭化鉄、オキシ臭化鉄、三ヨウ化鉄、二ヨウ化鉄、オキシヨウ化鉄、硫酸鉄(III)、硫化鉄(II)、硫化鉄(III)、フェロシアン化カリウム、フェリシアン化カリウム、フェロシアン化アンモニウム、フェリシアン化アンモニウム、フェロシアン化鉄、硝酸鉄(II)、硝酸鉄(III)、シュウ酸鉄(II)、シュウ酸鉄(III)、リン酸鉄(II)、リン酸鉄(III)フェロセン、酸化鉄(II)、酸化鉄(III)、四酸化三鉄、酢酸鉄(II)、クエン酸鉄(III)等の鉄化合物が挙げられる。これらの化合物は1種単独で用いてもよく2種以上を併用してもよい。
三塩化鉄、二塩化鉄、オキシ塩化鉄、鉄(III)エトキシド、鉄(III)イソプロポキシド、鉄(III)ブトキシド、鉄(III)アセチルアセトナート、鉄(III)イソプロポキシドアセチルアセトナート(Fe(acac)(O-iPr)2、Fe(acac)2(O-iPr))、フェロシアン化カリウム、フェリシアン化カリウム、フェロシアン化アンモニウム、フェリシアン化アンモニウム、酢酸鉄(II)、硝酸鉄(II)が好ましく、
三塩化鉄、二塩化鉄、鉄(III)エトキシド、鉄(III)イソプロポキシド、鉄(III)ブトキシド、鉄(III)アセチルアセトナート、フェロシアン化カリウム、フェリシアン化カリウム、フェロシアン化アンモニウム、フェリシアン化アンモニウム、酢酸鉄(II)がさらに好ましい。
水酸化ナトリウム、炭酸ナトリウム、硫酸ナトリウム、硝酸ナトリウム、酢酸ナトリウム、塩化ナトリウム等のナトリウム化合物;
チタンテトラエトキシド、チタンテトライソプロポキシド、チタンテトラブトキシド、チタンテトラペントキシド、チタンテトラアセチルアセトナート、チタンジイソプロポキシドジアセチルアセトナート(Ti(acac)2(O-iPr)2)チタンオキシジアセチルアセトナート、トリス(アセチルアセトナト)第二チタン塩化物([Ti(acac)3]2[TiCl6])、四塩化チタン、三塩化チタン、オキシ塩化チタン、四臭化チタン、三臭化チタン、オキシ臭化チタン、四ヨウ化チタン、三ヨウ化チタン、オキシヨウ化チタン等のチタン化合物;
ジルコニウムテトラエトキシド、ジルコニウムテトライソプロポキシド、ジルコニウムテトラブトキシド、ジルコニウムテトラペントキシド、ジルコニウムテトラアセチルアセトナート、ジルコニウムジイソプロポキシドジアセチルアセトナート(Zr(acac)2(O-iPr)2)、テトラキスジエチルアミノジルコニウム、テトラキス(2,2,6,6-テトラメチル-3,5-ヘプタンジオン)ジルコニウム、ジルコニウム(IV)ヘキサフルオロアセチルアセトナート、テトラ-1-メトキシ-2-メチル-2-プロポキシジルコニウム(IV)、四塩化ジルコニウム、オキシ塩化ジルコニウム、四臭化ジルコニウム、オキシ臭化ジルコニウム、四ヨウ化ジルコニウム、オキシヨウ化ジルコニウム等のジルコニウム化合物;
亜鉛エトキシド、亜鉛イソプロポキシド、亜鉛ブトキシド、亜鉛ペントキシド、亜鉛アセチルアセトナート、ビスジエチルアミノ亜鉛、ビス(2,2,6,6-テトラメチル-3,5-ヘプタンジオン)亜鉛、亜鉛ヘキサフルオロアセチルアセトナート、ビス-1-メトキシ-2-メチル-2-プロポキシ亜鉛、二塩化亜鉛、オキシ塩化亜鉛、二臭化亜鉛、オキシ臭化亜鉛、二ヨウ化亜鉛、オキシヨウ化亜鉛等の亜鉛化合物;
タンタルペンタエトキシド、タンタルペンタイソプロポキシド、タンタルペンタブトキシド、タンタルペンタペントキシド、タンタルテトラエトキシアセチルアセトナート、タンタルジイソプロポキシドジアセチルアセトナート(Ta(acac)2(O-iPr)2)、ペンタキスジエチルアミノタンタル、五塩化タンタル、オキシ塩化タンタル、五臭化タンタル、オキシ臭化タンタル、五ヨウ化タンタル、オキシヨウ化タンタル等のタンタル化合物;
が挙げられる。これらの化合物は1種単独で用いてもよく2種以上を併用してもよい。
水酸化ナトリウム、炭酸ナトリウム、酢酸ナトリウム、塩化ナトリウム、
チタンテトライソプロポキシド、チタンテトラアセチルアセトナート、チタンジイソプロポキシドジアセチルアセトナート(Ti(acac)2(O-iPr)2)、
ジルコニウムテトラエトキシド、四塩化ジルコニウム、オキシ塩化ジルコニウム、ジルコニウムテトライソプロポキシド、ジルコニウムテトラブトキシド、ジルコニウムテトラアセチルアセトナート、ジルコニウムジイソプロポキシドジアセチルアセトナート(Zr(acac)2(O-iPr)2)、
二塩化亜鉛、オキシ塩化亜鉛、亜鉛エトキシド、亜鉛イソプロポキシド、亜鉛ブトキシド、亜鉛アセチルアセトナート、
タンタルペンタエトキシド、五塩化タンタル、オキシ塩化タンタル、タンタルペンタイソプロポキシド、タンタルテトラエトキシアセチルアセトナート(Ta(acac)(O-C2H5)4)、タンタルジイソプロポキシドトリアセチルアセトナート(Ta(acac)3(O-iPr)2)が好ましく、
水酸化ナトリウム、炭酸ナトリウム、酢酸ナトリウム、塩化ナトリウム、
四塩化チタン、チタンテトライソプロポキシド、チタンテトラアセチルアセトナート、
四塩化ジルコニウム、オキシ塩化ジルコニウム、ジルコニウムテトライソプロポキシド、ジルコニウムテトラブトキシド、
二塩化亜鉛、亜鉛エトキシド、亜鉛イソプロポキシド、亜鉛ブトキシド、亜鉛アセチルアセトナート、
五塩化タンタル、タンタルペンタイソプロポキシドがさらに好ましい。
前記窒素含有有機化合物(2)としては、前記金属化合物(1)中の金属原子に配位可能な配位子となり得る化合物(好ましくは、単核の錯体を形成し得る化合物)が好ましく、多座配位子(好ましくは、2座配位子または3座配位子)となり得る(キレートを形成し得る)化合物がさらに好ましい。
前記窒素含有有機化合物(2)は、好ましくは、アミノ基、ニトリル基、イミド基、イミン基、ニトロ基、アミド基、アジド基、アジリジン基、アゾ基、イソシアネート基、イソチオシアネート基、オキシム基、ジアゾ基、ニトロソ基などの官能基、またはピロール環、ポルフィリン環、ピロリジン環、イミダゾール環、トリアゾール環、ピリジン環、ピペリジン環、ピリミジン環、ピラジン環、プリン環等の環(これらの官能基および環をまとめて「含窒素分子団」ともいう。)を有する。
分子中に酸素原子を含む前記窒素含有有機化合物(2)としては、前記含窒素分子団および前記含酸素分子団を有する化合物が好ましい。このような化合物は、工程(1)を経て、前記金属化合物(1)に由来する金属原子に特に強く配位できると考えられる。
前記アミノ酸としては、アラニン、アルギニン、アスパラギン、アスパラギン酸、システイン、グルタミン、グルタミン酸、グリシン、ヒスチジン、イソロイシン、ロイシン、リシン、メチオニン、フェニルアラニン、セリン、トレオニン、トリプトファン、チロシン、バリン、ノルバリン、グリシルグリシン、トリグリシンおよびテトラグリシンが好ましく、後述する接触工程をさらに経て得られる触媒の活性が高いことから、アラニン、グリシン、リシン、メチオニン、チロシンがより好ましく、後述する接触工程をさらに経て得られる触媒が極めて高い活性を示すことから、アラニン、グリシンおよびリシンが特に好ましい。
本発明の製造方法においては、工程(1)において、さらに(化学構造中に)フッ素を含有する化合物(3)も混合することによって、後述する接触工程をさらに経て、さらに高い触媒活性を有する電極触媒を製造することができる。
炭化水素基の水素原子の全部または一部がフッ素原子で置換された飽和または不飽和の脂肪族アルコール(炭素原子数は、たとえば1~30である。)、たとえばノナコサデカフルオロテトラデシルアルコール、ヘプタコサデカフルオロトリデシルアルコール、ペンタコサデカフルオロドデシルアルコール、ヘンイコサデカフルオロデシルアルコール、ヘプタデカフルオロオクチルアルコール、トリデカフルオロヘキシルアルコール、ノナフルオロブチルアルコール、ペンタフルオロエチルアルコール、トリフルオロメチルアルコール、2,2,2-トリフルオロエチルアルコール、6-パーフルオロヘキシルヘキサノール、2,5-ジ(トリフロロメチル)-3,6-ジオキソウンデカフルオロノナノール、パーフルオローメチルエチルヘキサノール、ドデカフルオロヘプタノール、オクタフルオロヘキサンジオールおよびドデカフルオロオクタンジオールなどのフルオロアルキルアルコール
が挙げられる。
前記フッ素原子を含有するアルコールまたはその誘導体は、好ましくは、一分子中に3個以上のフッ素原子を有する。
式[-[(CF2-CF2)-(CH2-CH(OR))n-]で表される構造を有する、テトラフルオロエチレン(CF2=CF2)とビニルエーテル(CH2=CHOR)との交互共重合により得られる交互共重合体(たとえば、ルミフロン(登録商標)(旭硝子(株)))、
フッ素ポリアリールエーテルケトン、フッ素ポリシアノアリールエーテル、3-(2-パーフルオロヘキシルエトキシ)-1,2-ジヒドロキシプロパン、
前記フッ素原子を含有するエーテルまたはその誘導体は、好ましくは、一分子中に3個以上のフッ素原子を有する。
式Rf-NR1R2(Rfは、水素原子の全部または一部がフッ素原子で置換された飽和または不飽和の脂肪族炭化水素基であり、R1およびR2は、それぞれ独立に、水素原子または、水素原子の全部もしくは一部がフッ素原子で置換されていてもよい炭素原子数1~10の炭化水素基である。)で表される飽和または不飽和の脂肪族アミン(Rfの炭素原子数は、たとえば1~30である。)、たとえばノナコサデカフルオロテトラデシルアミン、ヘプタコサデカフルオロトリデシルアミン、ペンタコサデカフルオロドデシルアミン、ヘンイコサデカフルオロデシルアミン、ヘプタデカフルオロオクチルアミン、ペンタデカフルオロヘプチルアミン、ウンデカフルオロペンチルアミン、ヘプタフルオロプロピルアミン、ペンタフルオロエチルアミン、トリフルオロメチルアミンおよび2,2,2-トリフルオロエチルアミンなどのフルオロアルキルアミン;
前記フルオロアルキルアミンの塩(一般式:A+[R4N]-;A+は、たとえばナトリウムイオン、カリウムイオン、アンモニウムイオンを表し、Rはそれぞれ独立に前記フルオロアルキルアミン中のフルオロアルキル基を表す。)(たとえば塩酸塩、硫酸塩、カルボン酸塩、燐酸塩)
が挙げられる。
前記フッ素原子を含有するアミンまたはその誘導体は、好ましくは、一分子中に3個以上のフッ素原子を有する。
炭化水素基の水素原子の全部または一部がフッ素原子で置換された飽和または不飽和の脂肪族カルボン酸(炭素原子数は、たとえば1~30である。)、たとえばノナコサデカフルオロテトラデカン酸、ヘプタコサデカフルオロトリデカン酸、ペンタコサデカフルオロドデカン酸、トリコサデカフルオロウンデカン酸、ヘンイコサデカフルオロデカン酸、ヘプタデカフルオロオクタン酸、トリデカフルオロヘキサン酸、ノナフルオロブタン酸、ペンタフルオロ酢酸、トリフルオロ酢酸、2,2,2-トリフルオロエチルカルボン酸、テトラフルオロクエン酸、ヘキサフルオログルタミン酸およびオクタフルオロアジピン酸などのフルオロアルキルカルボン酸;
アリール基中の水素原子の一部または全部が前記フルオロアルキルカルボン酸中のフルオロアルキル基で置換された芳香族カルボン酸、たとえばトリフルオロメチル安息香酸、トリフルオロメチルサリチル酸、トリフルオロメチルニコチン酸;
前記脂肪族カルボン酸のエステル(たとえば、メチルエステル、エチルエステル、アリールエステル(たとえば、フェニルエステル)、前記フッ素原子を含有するアルコールのエステル)、たとえばヘプタデカフルオロオクタン酸メチル、ヘプタデカフルオロオクタン酸エチル、ヘプタデカフルオロオクタン酸フェニル、ヘプタデカフルオロオクタン酸ヘプタデカフルオロオクチルエステル;
フッ素ポリアリールエーテルポリアリールエーテルエステル;
前記脂肪族カルボン酸の塩(たとえば、ナトリウム塩、カリウム塩、アンモニウム塩、アルキルアンモニウム(たとえば、メチルアンモニウム、トリメチルアンモニウム、エチルアンモニウム、ジエチルアンモニウム、およびトリエチルアンモニウム)塩、前記フルオロアルキルアミンの塩)、たとえばヘプタデカフルオロオクタン酸アンモニウム、ヘプタデカフルオロオクタン酸ナトリウム、ヘプタデカフルオロオクタン酸トリエチルアンモニウム;
前記脂肪族カルボン酸のアミド(一般式:Rf-CO-NR1R2、Rfは前記脂肪族カルボン酸中のフルオロアルキル基を、R1およびR2はそれぞれ独立に、水素原子の全部または一部がフッ素原子で置換されていてもよい炭素原子数1~10の炭化水素基(たとえば、メチル基、エチル基、フェニル基)表す。)たとえば、ヘプタデカフルオロオクタン酸アミド、ヘプタデカフルオロオクタン酸ジエチルアミド、ヘプタデカフルオロオクタン酸ヘプタデカフルオロオクチルアミド;
フッ素ポリアリールエーテルアミド;
フッ素ポリアリールエーテルイミド;
前記脂肪族カルボン酸の酸無水物(一般式:(Rf-CO)2O、Rfは前記脂肪族カルボン酸中のフルオロアルキル基を表す。)、たとえばヘプタデカフルオロオクタン酸無水物;
アミノ酸(たとえば、前記フルオロアルキルカルボン酸中のフルオロアルキル基を有するアミノ酸);
前記のカルボン酸またはその誘導体から誘導され得る置換基を有する有機化合物(高分子化合物であってもよい。)
が挙げられる。
前記フッ素原子を含有するカルボン酸またはその誘導体は、好ましくは、一分子中に3個以上のフッ素原子を有する。
テトラフルオロホウ酸四級アンモニウム塩(たとえば、テトラフルオロホウ酸テトラ-n-ブチルアンモニウム、テトラフルオロホウ酸テトラメチルアンモニウム、テトラフルオロホウ酸テトラエチルアンモニウム、テトラフルオロホウ酸テトラブチルアンモニウム、テトラフルオロホウ酸エチルトリメチルアンモニウム、テトラフルオロホウ酸ジエチルジメチルアンモニウム、テトラフルオロホウ酸トリエチルメチルアンモニウム、テトラフルオロホウ酸メチルトリプロピルアンモニウム、テトラフルオロホウ酸トリメチルプロピルアンモニウム、テトラフルオロホウ酸エチルジメチルプロピルアンモニウム、テトラフルオロホウ酸トリエチルプロピルアンモニウム、テトラフルオロホウ酸ジメチルジプロピルアンモニウム、テトラフルオロホウ酸エチルメチルジプロピルアンモニウム、テトラフルオロホウ酸トリメチルブチルアンモニウム、テトラフルオロホウ酸ジエチルメチルブチルアンモニウム、テトラフルオロホウ酸トリエチルブチルアンモニウム、テトラフルオロホウ酸ジメチルジブチルアンモニウム、テトラフルオロホウ酸エチルメチルジブチルアンモニウム、テトラフルオロホウ酸へキシルトリメチルアンモニウム(前記プロピルはn-プロピル、i-プロピルを含み、前記ブチルはn-ブチル、i-ブチル、s-ブチル、t-ブチルを含む。))、
テトラフルオロホウ酸四級ピリジニウム塩(たとえば、テトラフルオロホウ酸ピリジニウム、テトラフルオロホウ酸1-メチルピリジニウム、テトラフルオロホウ酸2-ブロモ-1-エチルピリジニウム、テトラフルオロホウ酸1-ブチルピリジニウム)、
テトラフルオロホウ酸四級イミダゾリウム塩(たとえば、テトラフルオロホウ酸1,3-ジメチルイミダゾリウム、テトラフルオロホウ酸1-エチル-3-メチルイミダゾリウム、テトラフルオロホウ酸1,3-ジエチルイミダゾリウム、テトラフルオロホウ酸1,2-ジメチル-3-エチルイミダゾリウム、テトラフルオロホウ酸1,2-ジメチル-3-プロピルイミダゾリウム、テトラフルオロホウ酸1-ブチル-3-メチルイミダゾリウム)、
アルキル基の水素原子の全部または一部がフッ素原子で置換されたフルオロアルキルホウ酸(たとえば、ノナコサデカフルオロテトラデシルホウ酸、ヘプタコサデカフルオロトリデシルホウ酸、ペンタコサデカフルオロドデシルホウ酸、ヘンイコサデカフルオロデシルホウ酸、ヘプタデカフルオロオクチルホウ酸、トリデカフルオロヘキシルホウ酸、ノナフルオロブチルホウ酸、ペンタフルオロエチルホウ酸、トリフルオロメチルホウ酸および2,2,2-トリフルオロエチルホウ酸)
前記フルオロアルキルホウ酸のモノエステルおよびジエステル(たとえば、メチルエステル、エチルエステル)、および
前記フルオロアルキルホウ酸の塩(たとえば、ナトリウム塩、カリウム塩、アンモニウム塩、メチルアンモニウム塩、ジメチルアンモニウム塩、トリメチルアンモニウム塩、およびトリエチルアンモニウム塩)、
が挙げられる。
ヘキサフルオロリン酸塩、たとえば、ヘキサフルオロリン酸四級アンモニウム塩(たとえば、ヘキサフルオロリン酸テトラ‐n‐ブチルアンモニウム、ヘキサフルオロリン酸テトラメチルアンモニウム、ヘキサフルオロリン酸テトラエチルアンモニウム、ヘキサフルオロリン酸テトラプロピルアンモニウム、ヘキサフルオロリン酸エチルトリメチルアンモニウム、ヘキサフルオロリン酸ジエチルジメチルアンモニウム、ヘキサフルオロリン酸トリエチルメチルアンモニウム、ヘキサフルオロリン酸トリメチルプロピルアンモニウム、ヘキサフルオロリン酸エチルジメチルプロピルアンモニウム、ヘキサフルオロリン酸トリエチルプロピルアンモニウム、ヘキサフルオロリン酸ジメチルジプロピルアンモニウム、ヘキサフルオロリン酸エチルメチルジプロピルアンモニウム、ヘキサフルオロリン酸トリメチルブチルアンモニウム、ヘキサフルオロリン酸エチルジメチルブチルアンモニウム、ヘキサフルオロリン酸トリエチルブチルアンモニウム、ヘキサフルオロリン酸トリプロピルブチルアンモニウム、ヘキサフルオロリン酸ジメチルジブチルアンモニウム、ヘキサフルオロリン酸エチルメチルジブチルアンモニウム、テトラフルオロリン酸へキシルトリメチルアンモニウム(前記プロピルはn-プロピル、i-プロピル、前記ブチルはn-ブチル、i-ブチル、s-ブチル、t-ブチルを含む。)、
ヘキサフルオロリン酸四級ピリジニウム塩(たとえば、ヘキサフルオロリン酸ピリジニウム、ヘキサフルオロリン酸1-メチルピリジニウム、ヘキサフルオロリン酸2-ブロモ-1-エチルピリジニウム)、
テトラフルオロリン酸四級イミダゾリウム塩(たとえば、テトラフルオロリン酸1,3-ジメチルイミダゾリウム、テトラフルオロリン酸1-エチル-3-メチルイミダゾリウム、テトラフルオロリン酸1,3-ジエチルイミダゾリウム、テトラフルオロリン酸1,2-ジメチル-3-エチルイミダゾリウム、テトラフルオロリン酸1,2-ジメチル-3-プロピルイミダゾリウム、テトラフルオロリン酸1-ブチル-3-メチルイミダゾリウム)、
ヘキサフルオロリン酸、
ヘキサフルオロリン酸の塩(たとえば、ナトリウム塩、カリウム塩、アンモニウム塩、アルキルアンモニウム(たとえば、メチルアンモニウム、ジメチルアンモニウム、トリメチルアンモニウム、エチルアンモニウム、ジエチルアンモニウム、およびトリエチルアンモニウム)塩)
一般式:(RO)nP=Oで表わされるフルオロアルキルリン酸エステル(式中、nは1~3であり、Rはアルキル基の水素原子の全部または一部がフッ素原子で置換されたフルオロアルキル基(たとえば、ノナコサデカフルオロテトラデシル基、ノナコサデカフルオロテトラデシル基、ヘプタコサデカフルオロトリデシル基、ペンタコサデカフルオロドデシル基、トリコサデカフルオロウンデシル基、ヘンイコサデカフルオロデシル基、ノナデカフルオロノニル基、ヘプタデカフルオロオクチル基、ペンタデカフルオロヘプチル基、トリデカフルオロヘキシル基、ウンデカフルオロペンチル基、ノナフルオロブチル基、ヘプタフルオロプロピル基、ペンタフルオロエチル基、トリフルオロメチル基および2,2,2-トリフルオロエチル基)である。)、
一般式:(RN)3P=O、(RN)2P=O(OH)、または(RN)P=O(OH)2(式中、Rは前記フルオロアルキル基を表す。)で表されるフルオロアルキルリン酸アミド、
一般式(RO)3P、(RO)2(OH)P、または(RO)(OH)2P(式中、前記フルオロアルキル基を表す。)で表わされるフルオロアルキル亜リン酸、
一般式(RN)3P、(RN)2P(OH)、(RN)P(OH)2(式中、Rは前記フルオロアルキル基を表す。)で表わされるフルオロアルキル亜リン酸アミド、
一般式:RPO(OH)2(式中、Rは前記フルオロアルキル基を表す。)で表わされるフルオロアルキルホスホン酸
が挙げられる。
テトラフルオロエチレンとパーフルオロ[2-(フルオロスルホニルエトキシ)プロピルビニルエーテル]との共重合体(たとえば、ナフィオン(NAFION(登録商標)、下式で表わされる構造を有する共重合体))、
前記フルオロアルキルスルホン酸のエステル(たとえば、メチルエステル、エチルエステル、アリールエステル(例えば、フェニルエステル))
前記フルオロアルキルスルホン酸の塩(一般式:A[RSO3]、Rは前記フルオロアルキル基を表す。)(ナトリウム塩、カリウム塩、アンモニウム塩、アルキルアンモニウム(たとえば、メチルアンモニウム、ジメチルアンモニウム、トリメチルアンモニウム、エチルアンモニウム、ジエチルアンモニウム、およびトリエチルアンモニウム)塩)、
前記フルオロアルキルスルホン酸のアミド(一般式:R-SO2-NR1R2、Rは前記フルオロアルキル基を、R1およびR2はそれぞれ独立に、水素原子の全部または一部がフッ素原子で置換されていてもよい炭素原子数1~10の炭化水素基(たとえば、メチル基、エチル基、フェニル基)表す。)、
前記フルオロアルキルスルホン酸の酸無水物(一般式:(R-SO2)2O、Rは前記フルオロアルキル基を表す。)、
前記フルオロアルキルスルホン酸のハロゲン化物(一般式:(R-SO2)X、Rは前記フルオロアルキル基を表す。Xはフッ素、塩素、臭素、ヨウ素を表す。)
が挙げられる。
より好ましくは、トリフルオロメタンスルホン酸、ヘプタデカフルオロオクタンスルホン酸、ノナフルオロ-1-ブタンスルホン酸、トリフルオロメタンスルホン酸テトラブチルアンモニウム、ヘプタデカフルオロオクタンスルホン酸アンモニウム、トリフルオロメタンスルホン酸第一鉄が挙げられ、
さらに、界面活性能がある骨格つまり、分子内に疎水性部位および親水性部位が存在する化合物が、反応系内の安定化が図れるのでさらに好ましい。
ホウ素、リンおよび硫黄からなる群から選ばれる少なくとも1種の元素Aを含む前記化合物(3)を用いる場合には、工程(1)で用いられる前記化合物(3)に含まれる元素Aの量(すなわち、工程(1)で用いられる前記化合物(3)に含まれる元素Aの総原子数)は、工程(1)で用いられる前記金属化合物(1)中の金属原子1モルに対して、通常0.01~3モル、好ましくは0.01~2モル、さらに好ましくは0.01~1モルである。
前記溶媒としては、たとえば水、アルコール類および酸類が挙げられる。アルコール類としては、エタノール、メタノール、ブタノール、プロパノールおよびエトキシエタノールが好ましく、エタノールおよびメタノールがさらに好ましい。酸類としては、酢酸、硝酸(水溶液)、塩酸、リン酸水溶液およびクエン酸水溶液が好ましく、酢酸および硝酸がさらに好ましい。これらは、1種単独で用いてもよく2種以上を併用してもよい。
前記溶媒は、前駆体製造用溶液100質量%中にたとえば50~95質量%となるような量で用いてもよい。
前記金属化合物(1)が、ハロゲン原子を含む場合には、これらの化合物は一般的に水によって容易に加水分解され、水酸化物や、酸塩化物等の沈殿を生じやすい。よって、前記金属化合物(1)がハロゲン原子を含む場合には、強酸を溶液(前駆体製造用溶液)中に1質量%以上となる量で添加することが好ましい。たとえば酸が塩酸であれば、溶液(前駆体製造用溶液)中の塩化水素の濃度が5質量%以上、より好ましくは10質量%以上となるように酸を添加すると、前記金属化合物(1)に由来する水酸化物、酸塩化物等の沈殿の発生を抑制しつつ、澄明な前駆体製造用溶液を得ることができる。
前記金属化合物(1)が金属錯体であって、かつ前記溶媒として水を単独でまたは水と他の化合物とを用いる場合にも、水酸化物または酸塩化物の沈殿の発生を抑制するための沈殿抑制剤を用いることが好ましい。この場合の沈殿抑制剤としては、ジケトン構造を有する化合物が好ましく、ジアセチル、アセチルアセトン、2,5-ヘキサンジオンおよびジメドンがより好ましく、アセチルアセトンおよび2,5-ヘキサンジオンがさらに好ましい。
工程(1)では、好ましくは、前記金属化合物(1)および前記沈殿抑制剤を含む溶液を調製して、次いでこの溶液と前記窒素含有有機化合物(2)および任意に前記化合物(3)とを混合して前駆体製造用溶液を得る。このように工程(1)を実施すると、前記沈殿の発生をより確実に抑制することができる。
工程(2)では、工程(1)で得られた前記前駆体製造用溶液から溶媒を除去する。
溶媒の除去は大気下で行ってもよく、不活性ガス(例えば、窒素、アルゴン、ヘリウム)雰囲気下で行ってもよい。不活性ガスとしては、コストの観点から、窒素およびアルゴンが好ましく、窒素がより好ましい。
また、前記混合物を収容している容器の真空度を調節しながら溶媒の除去を行う場合には、密閉できる容器で乾燥を行うこととなるため、容器ごと回転させながら溶媒の除去を行うこと、たとえばロータリーエバポレーターを使用して溶媒の除去を行うことが好ましい。
工程(3)では、工程(2)で得られた固形分残渣を熱処理して触媒前駆体を得る。
この熱処理の際の温度は、好ましくは500~1100℃であり、より好ましくは600~1050℃であり、さらに好ましくは700~950℃である。
静置法とは、静置式の電気炉などに工程(2)で得られた固形分残渣を置き、これを加熱する方法である。加熱の際に、量り取った前記固形分残渣は、アルミナボード、石英ボードなどのセラミックス容器に入れてもよい。静置法は、大量の前記固形分残渣を加熱することができる点で好ましい。
触媒活性の特に高い電極触媒を得るための触媒前駆体を得たい場合には、厳密な温度制御が可能な、電気を熱源とした電気炉を用いることが望ましい。
前記熱処理の際の圧力は特に制限されず、製造の安定性とコストなどを考慮して大気圧下で熱処理を行ってもよい。
触媒前駆体の製造方法(A)において溶媒を使用しない製造方法(すなわち、少なくとも金属化合物(1)と、窒素含有有機化合物(2)とを含み溶媒を含まない混合物を(好ましくは500~1100℃の温度で)熱処理して触媒前駆体を得る工程を含み、前記金属化合物(1)の一部または全部が銅を含有し、前記混合物に含まれる成分のうち少なくとも1つの成分が酸素原子を有する製造方法)により製造される触媒前駆体、および
金属元素として銅、および任意に鉄または前記金属元素(M3)を含有する金属炭窒化物を、酸素を含む不活性ガス中で熱処理する工程を含む製造方法(以下「触媒前駆体の製造方法(B)」ともいう。)により製造される触媒前駆体
が挙げられる。
銅を含有する化合物、および任意に鉄を含有する化合物または前記金属M3を含有する化合物を含む混合物を熱処理する(ただし、これらの化合物および熱処理雰囲気のいずれかには炭素および窒素が含まれる。)ことにより金属炭窒化物を製造する方法(I);
酸化銅、および任意に酸化鉄または前記金属元素(M3)の酸化物と炭素との混合物を、窒素雰囲気または窒素を含有する不活性ガス中で熱処理することにより金属炭窒化物を製造する方法(II)
などが挙げられる。
前記触媒前駆体は、好ましくは、解砕してから次の接触工程に供される。
接触工程においては、前記触媒前駆体と酸性溶液とを接触させることにより燃料電池用電極触媒を得る。
前記触媒前駆体と前記酸性溶液との割合は、これらの種類等にも依存するが、目安としては、酸性溶液が、前記触媒前駆体1gに対して、好ましくは10~50000mLであり、より好ましくは30~10000mLである。
本発明の製造方法は、好ましくは、前記接触工程の後に、前記接触処理物を洗浄する洗浄工程を含む。
前記洗浄工程は、たとえば、洗浄液および前記接触処理物を容器内に仕込むことによって、両者を接触させることにより実施される。この際、撹拌を行うことが好ましい。
<乾燥工程>
本発明の製造方法は、好ましくは、前記接触工程の後に、接触処理物を乾燥させる乾燥工程を含み、より好ましくは前記洗浄工程に乾燥工程を含む。
乾燥工程は、接触処理物の凝集を防ぐ観点から、好ましくは100℃以下の温度で行われる。
本発明に係る燃料電池用電極触媒は、前記の本発明に係る製造方法により製造される触媒である。
前記燃料電池用電極触媒は、白金触媒の代替触媒として使用することができる。
本発明の燃料電池用電極触媒の製造方法によれば、比表面積の大きな燃料電池用電極触媒が製造され、本発明の触媒のBET法で算出される比表面積は、好ましくは50m2/g以上、より好ましくは100~1200m2/g、さらに好ましくは200~900m2/gである。この比表面積は、たとえば、接触工程において触媒前駆体中の金属元素を多く除去するほど、大きくすることができる。
(燃料電池用電極触媒層)
本発明に係る燃料電池用電極触媒層は、前記燃料電池用電極触媒を含む。
また前記燃料電池用電極触媒層は、好ましくは、高分子電解質をさらに含む。前記高分子電解質としては、燃料電池用電極触媒層において一般的に用いられているものであれば特に限定されない。
本発明に係る電極は、前記燃料電池用電極触媒層と多孔質支持層とを有することを特徴としている。
本発明の膜電極接合体(以下「MEA」ともいう。)は、カソードとアノードと前記カソードおよび前記アノードの間に配置された電解質膜とを有する膜電極接合体であって、前記カソードおよび/または前記アノードは前記の本発明に係る電極である。好ましくは、前記カソードとして前記の本発明に係る電極が用いられ、この際、アノードとしては、従来公知の燃料電池用電極、たとえば白金系触媒を含む電極を用いてもよい。
本発明に係る燃料電池は、前記膜電極接合体を備える。
燃料電池の電極反応はいわゆる3相界面(電解質‐電極触媒‐反応ガス)で起こる。燃料電池は、使用される電解質などの違いにより数種類に分類され、溶融炭酸塩型(MCFC)、リン酸型(PAFC)、固体酸化物型(SOFC)、固体高分子型(PEFC)等がある。本発明に係る燃料電池としては、固体高分子型燃料電池が好ましい。
各種測定は、下記の方法により行なった。
<金属>
試料約0.1gを石英ビーカーに量り取り、硫酸,硝酸およびフッ酸を用いて試料を完全に加熱分解した。冷却後、この溶液を100mlに定容し、さらに適宜希釈し、ICP-OES(SII社製VISTA-PRO)またはICP-MS(Agilent社製HP7500)を用いて定量を行った。
試料約0.01gを量り取り、炭素硫黄分析装置(堀場製作所製EMIA-920V)にて測定を行った。
試料約0.01gを量り取り、Niカプセルに試料を封入して、酸素窒素分析装置(LECO製TC600)にて測定を行った。
試料数mgを、酸素気流下、水蒸気を通気しながら燃焼分解した。発生したガスを10mM Na2CO3(過酸化水素を含む。補正用標準Br‐:5ppm)に吸収させ、イオンクロマトグラフィーでフッ素の量を測定した。
試料燃焼装置:AQF-100((株)三菱化学アナリテック社製)
燃焼管温度:950℃(試料ボード移動による昇温分解)
イオンクロマトグラフィー測定条件
測定装置:DIONEX DX-500
溶離液:1.8mM Na2CO3+1.7mM NaHCO3
カラム(温度):ShodexSI-90(室温)
流速:1.0ml/分
注入量:25μl
検出器:電気伝導度検出器
サプレッサー:DIONEX ASRS-300
2.BET比表面積測定;
島津製作所株式会社製 マイクロメリティクス ジェミニ2360を用いてBET比表面積を測定した。前処理時間、前処理温度は、それぞれ30分、200℃に設定した。
(1)アノードの作製
(i)アノード用インクの調製
純水50mlに、白金担持カーボン(TEC10E60E、田中貴金属工業製)0.6gと、プロトン伝導性材料(NAFION(登録商標))0.25gを含有する水溶液(5%ナフィオン(NAFION(登録商標))水溶液、和光純薬工業製)5gとを入れて、超音波分散機(UT-106H型シャープマニファクチャリングシステム社製)で1時間混合することにより、アノード用インクを調製した。
ガス拡散層(カーボンペーパー(TGP-H-060、東レ社製))を、アセトンに30秒間浸漬して脱脂した後、乾燥させ、次いで10%のポリテトラフルオロエチレン(以下「PTFE」ともいう。)水溶液に30秒間浸漬した。
次に、5cm×5cmの大きさとした前記GDLの表面に、自動スプレー塗布装置(サンエイテック社製)により、80℃で、前記アノード用インクを塗布した。スプレー塗布を繰り返し行うことにより、単位面積あたりの白金(Pt)量が1mg/cm2であるアノード触媒層を有する電極(以下、単に「アノード」ともいう。)を作製した。
(i)カソード用インクの調製
実施例および比較例で得られた各触媒について、触媒0.2g、電子伝導性材料としてのカーボンブラック(ケッチェンブラックEC300J、ライオン(株))0.05g、およびプロトン伝導性材料水溶液(ナフィオン(NAFION(登録商標))を0.14g含有する水溶液、和光純薬工業(株))0.75gを、自転・公転ミキサー(あわとり練太郎、(株)シンキー)で15分間混合することにより、カソード用インクを調製した。
ガス拡散層(カーボンペーパー(TGP-H-060、東レ(株)))を、アセトンに30秒間浸漬して脱脂した後、乾燥させ、次いで10%のポリテトラフルオロエチレン(PTFE)水分散液(PTFE60%水分散液(アルドリッチ製)を水で6倍希釈したもの)に30秒間浸漬した。
次に、5cm×5cmの大きさとした前記GDLの表面に、バーコーター塗布法により、80℃で、前記カソード用インクを塗布しカソード触媒層をGDL表面に有する電極(以下、単に「カソード」ともいう。)を作製した。
電解質膜としてのナフィオン(NAFION(登録商標))膜(NR-212、DuPont社製)を、前記(2)で作製したカソードおよび前記(1)で作製したアノードで挟み、カソード触媒層およびアノード触媒層が前記電解質膜に密着するように、ホットプレス機を用いて、温度140℃、圧力3MPaで6分間かけてこれらを熱圧着することにより、前記カソードと前記アノードとの間に前記電解質膜を配置した燃料電池用膜電極接合体(以下「MEA」ともいう。)を作製した。
前記MEAを、2つのシール材(ガスケット)、2つのガス流路付きセパレーター、2つの集電板および2つのラバーヒータで順次挟んでボルトで固定し、これらを所定の面圧(4N)になるように締め付けて、固体高分子型燃料電池の単セル(セル面積:5cm2)を作製した。
前記単セルを80℃、アノード加湿器を80℃、カソード加湿器を80℃に温度調節した。アノード側に燃料として水素を流量0.1リットル/分で供給し、カソード側に酸化剤として酸素を流量0.1リットル/分で供給し、両側ともに300kPaの背圧をかけながら、前記単セルに0.1A/cm2の定電流負荷を与えた際のセル電圧の経時変化を測定し、30秒ごとに取得されたセル電圧のデータから、電圧の経時変化をプロットして電圧の経時変化曲線を作成した(図1~6)。そして、この電圧の経時変化曲線に基づき、連続運転開始後に一旦急激な電圧変動が生じる段階(段階a)と、該段階a後の、電圧変動が急激に小さくなる遷移段階(段階b)と、該段階b後の、電圧変動が小さい状態でほぼ一定になる段階(段階c)とを把握した。多くの場合、運転開始5時間程度で前記段階cに移行する。
また、前記段階cに移行した後の部分のうち、セル電圧の時間変化の比較的少ない部分(連続運転開始5時間後から20時間後までの間)におけるセル電圧のプロットを最小二乗法によって直線に近似し、得られた近似直線の傾きの絶対値(すなわち、単位時間当たりの電圧降下。「電圧降下の傾き」ともいう。)が小さいほど、触媒耐久性が高いと評価した。
ビーカーに、メタノール50mlを入れ、これを攪拌しながら二塩化銅2.75g(20.45mmol)、5%ナフィオン(NAFION(登録商標))溶液(DE521、デュポン社)12.5ml、酢酸鉄(II)355mg(2.05mmol)を順次加えた。得られた溶液にピラジンカルボン酸7.61g(60.8mmol)を少量ずつ加えた後、3時間の攪拌を行い混合物(1)を得た。なおこの攪拌中に、時間の経過とともに沈殿物が生じた。
[実施例1]
1.燃料電池用電極触媒の調製;
各原料の量を4倍としたこと以外は比較例1と同様の方法により、触媒前駆体(1)を製造した。
[比較例2]
ビーカーに、メタノール200mlを入れ、これを攪拌しながら二塩化銅11.0g(81.8mmol)、5%ナフィオン(NAFION(登録商標))溶液(DE521、デュポン社)50ml、酢酸鉄(II)1.42mg(8.18mmol)を順次加えた。得られた溶液にピラジンカルボン酸30.5g(0.25mol)を少量ずつ加えた後、3時間の攪拌を行い(なおこの攪拌中に、時間の経過とともに沈殿物が生じた。)、さらに炭酸ナトリウム1.73g(16.4mmol)を蒸留水60mlに溶解させて調製した溶液を少量ずつ添加して、混合物(2)を得た。
触媒(c2)の評価結果を表1に示す。
各原料の量を4倍としたこと以外は比較例2と同様の方法により、触媒前駆体(2)を製造した。
触媒(2)の評価結果を表1に示す。
二塩化銅2.75gを四塩化チタン2.56g(13.5mmol)および二塩化銅0.907g(6.75mmol)に変更し、ピラジンカルボン酸の量を10.2g(81.8mmol)に変更したこと以外は比較例1と同様の操作を行い、439mgの粉末状の触媒前駆体(3)(以下「触媒(c3)」ともいう。)を得た。なお、この過程で得られた焼成用粉末の質量は4.87gであった。
触媒(c3)の評価結果を表1に示す。
各原料の量を4倍としたこと以外は比較例3と同様の方法により、触媒前駆体(3)を製造した。
[比較例4]
ビーカーに、アセチルアセトン1.30g(13.0mmol)を入れ、これを攪拌しながらジルコニウムテトラブトキシド3.97g(10.4mmol)および酢酸8mlを加え、ジルコニウム溶液(4)を調製した。
ロータリーエバポレーターを用い、窒素雰囲気の減圧下で、ホットスターラーの温度を約100℃に設定し、前記混合物(4)を加熱かつ攪拌しながら、溶媒をゆっくり蒸発させた。完全に溶媒を蒸発させて得られた固形物残渣を自動乳鉢で30分間すり潰して、5.34gの焼成用粉末(4)を得た。
触媒前駆体(c4)の評価結果を表1に示す。
各原料の量を2倍としたこと以外は比較例4と同様の方法により、触媒前駆体(4)を製造した。
触媒(4)の評価結果を表1に示す。
ビーカーに、酢酸158mlを入れ、これを攪拌しながら亜鉛アセチルアセトナート4.64g(17.6mmol)を加え、亜鉛溶液(5)を調製した。
ロータリーエバポレーターを用い、窒素雰囲気の減圧下で、ホットスターラーの温度を約100℃に設定し、前記混合物(5)を加熱かつ攪拌しながら、溶媒をゆっくり蒸発させた。完全に溶媒を蒸発させて得られた固形物残渣を自動乳鉢で30分間すり潰して、5.76gの焼成用粉末(5)を得た。
触媒(c5)の評価結果を表1に示す。
各原料の量を3倍としたこと以外は比較例5と同様の方法により、触媒前駆体(5)を製造した。
[比較例6]
二塩化銅2.75gを二塩化銅1.81g(13.5mmol)および五塩化タンタル2.42g(6.75mmol)に変更し、ピラジンカルボン酸の量を10.2g(81.8mmol)に変更したこと以外は比較例1と同様の操作を行い、890mgの粉末状の触媒前駆体(6)(以下「触媒(c6)」ともいう。)を得た。なお、この過程で得られた焼成用粉末の質量は4.27gであった。
触媒(c6)の評価結果を表1に示す。
比較例6と同様の方法により触媒前駆体(6)を製造した。
触媒前駆体(1)を834mgの触媒前駆体(6)に変更し、濃塩酸の量を30mlに変更したこと以外は実施例1と同様の操作を行い、516mgの触媒(6)を製造した。
触媒(6)の評価結果を表1に示す。
二塩化銅2.75gを四塩化チタン2.56g(13.5mmol)に変更し、ピラジンカルボン酸の量を10.2g(81.8mmol)に変更し、酢酸鉄(II)の量を71mg(0.41mmol)に変更したこと以外は比較例1と同様の操作を行い、323mgの粉末状の触媒(c7)を得た。なお、この過程で得られた焼成用粉末の質量は3.21gであった。
触媒(c7)の評価結果を表1に示す。
比較例4と同様にジルコニウム溶液(4)を調製した。
ビーカーに、水200ml、エタノール160ml、および酢酸200mlを入れ、これらを攪拌しながらピラジンカルボン酸11.98g(96.0mmol)、5%ナフィオン(NAFION(登録商標))溶液(DE521、デュポン社)5mlを加えて、酢酸鉄(II)44mg(0.251mmol)を少量ずつ加えて10分程かけて溶解させた。次に温度を室温に保ちながら、かつ攪拌しながら、上記のジルコニウム溶液(4)を10分間かけて滴下し、溶液(c8)を得た。
触媒(c8)の評価結果を表1に示す。
Claims (13)
- 金属元素、炭素、窒素および酸素の各原子を含み、前記金属元素として銅を含む触媒前駆体を準備する工程、および
前記触媒前駆体と酸性溶液とを接触させて触媒を得る接触工程
を含む、燃料電池用電極触媒の製造方法。 - 前記金属元素の10~99モル%が銅である請求項1に記載の燃料電池用電極触媒の製造方法。
- 前記金属元素として鉄をさらに含む請求項1または2に記載の燃料電池用電極触媒の製造方法。
- 前記金属元素の1~20モル%が鉄である請求項3に記載の燃料電池用電極触媒の製造方法。
- 前記金属元素としてナトリウム、チタン、ジルコニウム、亜鉛およびタンタルからなる群から選ばれる少なくとも1種をさらに含む請求項1~4のいずれかに記載の燃料電池用電極触媒の製造方法。
- 前記酸性溶液が塩化水素、硫酸、クエン酸および酢酸から選ばれる少なくとも1種の酸の水溶液である請求項1~5のいずれかに記載の燃料電池用電極触媒の製造方法。
- 前記接触工程を下記条件で行う請求項1~6のいずれかに記載の燃料電池用電極触媒の製造方法。
温度:15~100℃
時間:0.1~500時間
酸の濃度:0.01~15N - 請求項1~7のいずれかに記載の製造方法により製造される燃料電池用電極触媒。
- 請求項8に記載の燃料電池用電極触媒を含む燃料電池用電極触媒層。
- 燃料電池用電極触媒層と多孔質支持層とを有する電極であって、前記燃料電池用電極触媒層が請求項9に記載の燃料電池用電極触媒層である電極。
- カソードとアノードと前記カソードおよび前記アノードの間に配置された電解質膜とを有する膜電極接合体であって、前記カソードおよび/または前記アノードが請求項10に記載の電極である膜電極接合体。
- 請求項11に記載の膜電極接合体を備える燃料電池。
- 固体高分子型燃料電池である請求項12に記載の燃料電池。
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PCT/JP2013/058990 WO2013150939A1 (ja) | 2012-04-05 | 2013-03-27 | 燃料電池用電極触媒の製造方法、燃料電池用電極触媒およびその用途 |
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US (1) | US20150093681A1 (ja) |
JP (1) | JP6124871B2 (ja) |
CN (1) | CN104205446B (ja) |
WO (1) | WO2013150939A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101781801B1 (ko) * | 2014-04-25 | 2017-09-27 | 상명대학교산학협력단 | 에틸디메틸프로필암모늄 테트라플루오로보레이트를 이용한 전기이중층 커패시터 |
CN112201796A (zh) * | 2020-09-29 | 2021-01-08 | 南京大学 | 一种m-n-c单原子催化剂的制备方法及应用 |
KR20220085191A (ko) * | 2020-12-15 | 2022-06-22 | 연세대학교 산학협력단 | 밀푀유 모양 다중구조체, 이의 제조방법, 상기 다중구조체를 포함하는 슈퍼커패시터용 전극 |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JP6308090B2 (ja) * | 2014-10-02 | 2018-04-11 | トヨタ自動車株式会社 | コアシェル触媒の製造方法 |
CN107742731B (zh) * | 2017-09-30 | 2019-12-03 | 湖南工业大学 | 一种含铜氧还原催化剂及其制备方法和应用 |
CN114479038A (zh) * | 2020-10-23 | 2022-05-13 | 中国石油化工股份有限公司 | 一种钛系催化剂及其制备方法和应用 |
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- 2013-03-27 WO PCT/JP2013/058990 patent/WO2013150939A1/ja active Application Filing
- 2013-03-27 JP JP2014509120A patent/JP6124871B2/ja not_active Expired - Fee Related
- 2013-03-27 CN CN201380016438.2A patent/CN104205446B/zh not_active Expired - Fee Related
- 2013-03-27 US US14/390,520 patent/US20150093681A1/en not_active Abandoned
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KR101781801B1 (ko) * | 2014-04-25 | 2017-09-27 | 상명대학교산학협력단 | 에틸디메틸프로필암모늄 테트라플루오로보레이트를 이용한 전기이중층 커패시터 |
CN112201796A (zh) * | 2020-09-29 | 2021-01-08 | 南京大学 | 一种m-n-c单原子催化剂的制备方法及应用 |
CN112201796B (zh) * | 2020-09-29 | 2022-02-08 | 南京大学 | 一种m-n-c单原子催化剂的制备方法及应用 |
KR20220085191A (ko) * | 2020-12-15 | 2022-06-22 | 연세대학교 산학협력단 | 밀푀유 모양 다중구조체, 이의 제조방법, 상기 다중구조체를 포함하는 슈퍼커패시터용 전극 |
KR102422088B1 (ko) | 2020-12-15 | 2022-07-18 | 연세대학교 산학협력단 | 밀푀유 모양 다중구조체, 이의 제조방법, 상기 다중구조체를 포함하는 슈퍼커패시터용 전극 |
Also Published As
Publication number | Publication date |
---|---|
JPWO2013150939A1 (ja) | 2015-12-17 |
CN104205446A (zh) | 2014-12-10 |
US20150093681A1 (en) | 2015-04-02 |
JP6124871B2 (ja) | 2017-05-10 |
CN104205446B (zh) | 2017-06-16 |
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