WO2013099525A1 - Membrane/electrode assembly and fuel cell using same - Google Patents

Membrane/electrode assembly and fuel cell using same Download PDF

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Publication number
WO2013099525A1
WO2013099525A1 PCT/JP2012/081232 JP2012081232W WO2013099525A1 WO 2013099525 A1 WO2013099525 A1 WO 2013099525A1 JP 2012081232 W JP2012081232 W JP 2012081232W WO 2013099525 A1 WO2013099525 A1 WO 2013099525A1
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Prior art keywords
palladium
fuel cell
membrane
ruthenium oxide
anode
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PCT/JP2012/081232
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French (fr)
Japanese (ja)
Inventor
鈴木　修一
純 川治
水上　貴彰
大剛 小野寺
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株式会社 日立製作所
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Publication of WO2013099525A1 publication Critical patent/WO2013099525A1/en

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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
    • H01M8/1009—Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
    • H01M8/1011—Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
    • 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
    • H01M4/9041—Metals or alloys
    • H01M4/905—Metals or alloys specially used in fuel cell operating at high temperature, e.g. SOFC
    • H01M4/9058—Metals or alloys specially used in fuel cell operating at high temperature, e.g. SOFC of noble metals or noble-metal based alloys
    • 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
    • H01M8/1009—Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
    • H01M8/1011—Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
    • H01M8/1013—Other direct alcohol fuel cells [DAFC]
    • 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
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • 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 membrane / electrode assembly in which an electrode and an electrolyte membrane are joined, and a fuel cell using the membrane / electrode assembly.
  • a fuel cell is a generator that consists of at least a solid or liquid electrolyte and two electrodes that induce a desired electrochemical reaction, an anode and a cathode, and converts the chemical energy of the fuel directly into electrical energy with high efficiency. is there.
  • Such a fuel cell uses a cation exchange type solid polymer electrolyte membrane as an electrolyte, and a fuel cell using hydrogen as a fuel is called a polymer electrolyte fuel cell (PEFC), which uses methanol as fuel.
  • PEFC polymer electrolyte fuel cell
  • DMFCs and DEFCs using liquid fuels are attracting attention as effective for small portable or portable power sources because of their high volumetric energy density.
  • DMFCs and DEFCs using liquid fuels are attracting attention as effective for small portable or portable power sources because of their high volumetric energy density.
  • DMFC methanol supplied to the anode is oxidized, and the generated hydrogen ions are carried to the cathode and participate in the oxygen reduction reaction to generate water (formulas 1 to 3).
  • the anode atmosphere is acidic.
  • platinum or platinum-ruthenium which is excellent in methanol oxidation activity is used as a catalyst for promoting methanol oxidation.
  • Patent Document 1 there is a fuel cell using an anion exchange type solid polymer electrolyte membrane.
  • oxygen reacts with water at the cathode, and the resulting hydroxide ions are transported to the anode and participate in the methanol oxidation reaction.
  • Carbon dioxide and water are produced (Equations 4-6).
  • the atmosphere of the anode is alkaline.
  • platinum and its compounds platinum-ruthenium, platinum-ruthenium-molybdenum, platinum-tin are used as a catalyst for promoting the oxidation of methanol.
  • An alkaline fuel cell using an anion exchange type solid polymer electrolyte does not have a strongly acidic atmosphere inside the fuel cell unlike an acid type fuel cell using a cation exchange type electrolyte. For this reason, attention has been paid to the fact that low-cost metals other than platinum can be used for the catalyst. However, a catalyst other than platinum requires a large overvoltage required for methanol oxidation, and a catalyst having higher activity is desired.
  • an object of the present invention is to provide a high-performance membrane / electrode assembly for a fuel cell having a catalyst having a higher catalytic activity than platinum and an inexpensive catalyst.
  • a membrane / electrode assembly includes an anode for oxidizing fuel, a cathode for reducing oxygen, and an anion exchange type solid polymer electrolyte membrane disposed between the anode and the cathode.
  • the anode contains palladium and ruthenium oxide.
  • the fuel is an aqueous solution containing methanol.
  • composition of palladium and ruthenium contained in the anode is in the range of 85:15 to 35:65.
  • a fuel cell can be obtained by using such a membrane / electrode assembly, a member for supplying fuel, a member for supplying oxygen, and a member for current collection. It is also possible to provide a fuel cell system equipped with this fuel cell.
  • Fuel is electrochemically oxidized at the anode and oxygen is reduced at the cathode, resulting in a difference in electrical potential between the electrodes.
  • a load is applied as an external circuit between the two electrodes, hydroxide ions move in the electrolyte, and electric energy is extracted from the external load.
  • the cross-sectional schematic diagram of the membrane / electrode assembly for fuel cells which concerns on a present Example The cross-sectional schematic diagram of the anode which concerns on a present Example.
  • the cross-sectional schematic diagram of palladium and ruthenium oxide carry
  • the cross-sectional schematic diagram of palladium and ruthenium oxide carry
  • the cross-sectional schematic diagram of palladium and ruthenium oxide carry
  • the cross-sectional schematic diagram of palladium and ruthenium oxide carry
  • the cross-sectional schematic diagram of palladium and ruthenium oxide carry
  • 1 is an exploded perspective view of a fuel cell according to the present embodiment.
  • the cross-sectional schematic diagram of the fuel cell power generation system which concerns on a present Example.
  • FIG. 1 is a schematic sectional view of a membrane / electrode assembly for a fuel cell according to this example.
  • An anode 12 and a cathode 13 are disposed on both sides of the anion exchange type solid polymer electrolyte membrane 11.
  • the anode diffusion layer 14 and the cathode diffusion layer 15 are disposed on the opposite side of the anode 12 and the cathode 13 from the anion exchange type solid polymer electrolyte membrane 11.
  • a liquid fuel containing an organic substance is supplied to the anode 12, and a gas containing oxygen such as air is supplied to the cathode 13.
  • the anode 12 contains palladium and ruthenium oxide as catalysts.
  • the vicinity of palladium and ruthenium oxide becomes an environment where there are more hydroxide ions than hydrogen ions, and shows high organic matter oxidation activity.
  • the palladium intended by the present embodiment is mainly composed of a metal component, and preferably has a minimum amount of hydroxide and oxide components.
  • ruthenium oxide is mainly composed of hydroxide and oxide components, and preferably has as little metal components as possible. In order to prevent aggregation of palladium and ruthenium oxide and increase the specific surface area, it is preferable that palladium and ruthenium oxide are supported on a catalyst carrier.
  • the catalyst support desirably has good electron conductivity and a large specific surface area.
  • a carbon support or a porous metal body can be used.
  • a carbon support is particularly preferable, and for example, carbon black, carbon nanotube, mesoporous carbon, activated carbon, and the like can be used.
  • the anode 12 can be prevented from dropping into the liquid fuel by containing a resin that binds the catalyst.
  • polytetrafluoroethylene which is a fluorine resin, polystyrene, polyether ketone, polyether sulfone, or the like, which is a hydrocarbon resin
  • a solid polymer having an anion exchange group as the resin to be bound, hydroxide ions supplied from the cathode 13 through the anion exchange type solid polymer electrolyte membrane 11 are transmitted to palladium and ruthenium oxide. Since it becomes easy, it is preferable.
  • alkaline compounds such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate are included in the liquid fuel, these conduct hydroxide ions, so that the binding resin has an anion exchange group. It is not essential to have it.
  • a solid polymer having an anion exchange group for example, a hydrocarbon resin in which a quaternary amine group or a phosphonium group which is an anion exchange group is introduced can be used.
  • the anion exchange type solid polymer electrolyte membrane 11 is not particularly limited, but is similarly polystyrene, polyetherketone, polyethersulfone into which a quaternary amine group or phosphonium group which is an anion exchange group is introduced.
  • the catalyst included in the cathode 13 is not particularly limited as long as it has a catalytic activity for oxygen reduction.
  • platinum, palladium, iron, cobalt, nickel, nitrogen-containing carbon, or the like is used. And those supported on a carbon support are preferred.
  • a resin that binds the catalyst to the cathode 13 as in the case of the anode 12.
  • Porous materials such as carbon paper and carbon cloth can be used for the anode diffusion layer 14 and the cathode diffusion layer 15, but they have electronic conductivity and have a path for fuel and oxygen to diffuse.
  • the material is not particularly limited as long as the material is stable in the fuel cell power generation environment.
  • FIG. 2 is a schematic cross-sectional view of the anode according to this example.
  • An anode 22 is formed on the anion exchange type solid polymer electrolyte membrane 21.
  • a carbon black 23 carrying palladium and ruthenium oxide is bound to the anode 22 by a resin 24.
  • the amount of palladium and ruthenium oxide contained in the anode 22 is not particularly limited, but is preferably 0.1 mg / cm 2 or more with respect to the projected area. When the amount is less than 0.1 mg / cm 2 , it is difficult to obtain a sufficient output density.
  • the upper limit of the amount of palladium and ruthenium oxide is not particularly limited, but is preferably 10 mg / cm 2 or less.
  • the amount of palladium and ruthenium oxide supported when carbon black is used as a carrier is not particularly limited, but may be 10 to 80% by weight based on the total of carbon black, palladium and ruthenium oxide. preferable. If it is 10 wt% or less, when the desired palladium and ruthenium oxide are to be included in the anode 22, the anode 22 becomes too thick and the diffusibility of the liquid fuel containing organic matter becomes worse. On the other hand, if it is 80% by weight or more, it becomes difficult to support palladium and ruthenium oxide on carbon black, and the advantage of using a carrier is reduced.
  • anode 22 on the anion exchange type solid polymer electrolyte membrane 21 for example, carbon black 23 carrying palladium and ruthenium oxide is mixed with an alcohol solution containing a resin 24, and an anion exchange type is then performed.
  • a method of spray coating on the solid polymer electrolyte membrane 21 can be used.
  • FIG. 3 shows a schematic cross-sectional view of palladium and ruthenium oxide supported on carbon black according to this example.
  • Ruthenium oxide 33 is supported on the surface of the carbon black 31 in layers, and palladium 32 is supported on the ruthenium oxide 33.
  • FIG. 4 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example. Palladium 32 is supported on the surface of the carbon black 31 in layers, and ruthenium oxide 33 is supported on the palladium 32.
  • FIG. 5 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example.
  • FIG. 6 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example. Palladium 32 is supported on the surface of the carbon black 31, and ruthenium oxide 33 is supported on the palladium 32.
  • the ruthenium oxide 33 is preferably supported on the palladium 32 as much as possible, but even if it is directly supported on the carbon black 31, it does not interfere.
  • FIG. 6 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example. Palladium 32 is supported on the surface of the carbon black 31, and ruthenium oxide 33 is supported on the palladium 32.
  • the ruthenium oxide 33 is preferably supported on the palladium 32 as much as possible, but even if it is directly supported on the carbon black 31, it does not interfere.
  • FIG. 6 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example. Palladium 32
  • FIG. 7 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example.
  • Palladium 32 and ruthenium oxide 33 are supported on the surface of the carbon black 31.
  • the palladium 32 and the ruthenium oxide 33 are in contact with each other as much as possible.
  • it is preferable that as many interfaces as possible are formed between the palladium and ruthenium oxide.
  • the ruthenium oxide 33 is supported as a ruthenium oxide by dissolving a ruthenium compound in water in which carbon black 31 is dispersed and adding an alkaline substance while stirring the compound to increase the pH to 3 or more. can do.
  • a ruthenium compound for example, ruthenium chloride, hexaammineruthenium chloride or the like can be used.
  • potassium hydroxide, sodium hydroxide, etc. can be used as an alkaline substance which adjusts pH.
  • palladium 32 is supported by dispersing carbon black 31 supporting ruthenium oxide 33 in water, adding an aqueous solution containing a palladium compound and a reducing agent, and heating to reduce the palladium compound as metallic palladium.
  • palladium chloride, palladium nitrate, dinitrodiamine palladium and the like can be used as the palladium compound
  • hypophosphorous acid, phosphorous acid, sodium borohydride, formaldehyde and the like can be used as the reducing agent.
  • the method of supporting palladium after supporting ruthenium oxide has been described, but in the same manner, after supporting palladium first, and then supporting ruthenium oxide, ruthenium oxide is supported on palladium. can do.
  • ruthenium needs to be used in an oxide state, and if it is in a metal state, the catalytic activity is lowered. Accordingly, when synthesizing the catalyst or after the synthesis, heat treatment in a reducing atmosphere containing hydrogen is not desirable because ruthenium oxide is reduced to a metal. Further, when palladium and ruthenium are alloyed, ruthenium is in a metallic state, which is not desirable.
  • the state of the ruthenium oxide, RuO 2, RuO 3, such as RuO 4 and the like it is preferably as low as possible ruthenium metal state, ruthenium in a metal state is preferably 10 atomic% or less.
  • the state of ruthenium can be analyzed by XPS, for example, and can be quantified by separating the Ru3d spectrum into peaks. Note that peaks of metals Ru, RuO 2 , RuO 3 , and RuO 4 appear in the vicinity of 280.1, 280.7, 282.5, and 283.3 eV, respectively. Moreover, although the state of palladium is not particularly limited, it is preferable that a large amount of palladium in the metal state is present. Similarly, the state of palladium can be analyzed by XPS, and the peaks of metals Pd, PdO, and PdO 2 appear around 335.2, 336.3, 337.9 eV, respectively.
  • the oxidation activity of the organic substance 4 times or more of the platinum catalyst can be obtained.
  • high activity cannot be obtained with palladium alone or ruthenium oxide alone.
  • Example 1 Carbon black (1.0 g), 0.66 g (RuCl 3) , and 1000 ml of pure water were mixed, and while stirring, a 1 mol / L sodium hydroxide aqueous solution was gradually added dropwise to maintain the pH at 4. Ruthenium oxide was supported on carbon black. Thereafter, the reaction solution was filtered, thoroughly washed with pure water, and then dried at 80 ° C. in the air. Next, the powder obtained, 0.57 g of PdCl 2 , 0.48 g of formaldehyde, and 1000 ml of pure water were mixed, and while heating and stirring, a 1 mol / L sodium hydroxide aqueous solution was gradually added.
  • the anode catalyst obtained in this example has a form in which ruthenium oxide is supported on carbon black and palladium is supported on the surfaces of carbon black and ruthenium oxide.
  • Example 2 In the same manner as in Example 1 except that the weights of RuCl 3 and PdCl 2 used were 0.33 g and 0.84 g, respectively, an anode catalyst having palladium and ruthenium oxide supported on carbon black according to this example was used. Obtained.
  • the anode catalyst obtained in this example has a form in which ruthenium oxide is supported on carbon black and palladium is supported on the surfaces of carbon black and ruthenium oxide.
  • Example 3 An anode catalyst in which palladium and ruthenium oxide were supported on carbon black according to this example was prepared in the same manner as in Example 1 except that the weights of RuCl 3 and PdCl 2 used were 1.01 g and 0.29 g, respectively. Obtained.
  • the anode catalyst obtained in this example has a form in which ruthenium oxide is supported on carbon black and palladium is supported on the surfaces of carbon black and ruthenium oxide.
  • Example 4 Carbon black (1.0 g), 0.57 g of PdCl 2 , 0.48 g of formaldehyde, and 1000 ml of pure water are mixed, and a 1 mol / L aqueous sodium hydroxide solution is gradually added dropwise while heating and stirring. By keeping the pH at 8, the palladium was supported on the carbon black. Thereafter, the reaction solution was filtered, thoroughly washed with pure water, and then dried at 80 ° C. in the air. Next, the obtained powder, 0.66 g of RuCl 3 and 1000 ml of pure water were mixed, and while stirring, a 1 mol / L aqueous sodium hydroxide solution was gradually added dropwise to maintain the pH at 4.
  • the anode catalyst obtained in this example has a form in which palladium is supported on carbon black and ruthenium oxide is supported on the surfaces of carbon black and palladium.
  • Example 5 An anode catalyst in which palladium and ruthenium oxide were supported on carbon black according to this example was prepared in the same manner as in Example 5 except that the weights of PdCl 2 and RuCl 3 used were 0.84 g and 0.33 g, respectively. Obtained.
  • the anode catalyst obtained in this example has a form in which palladium is supported on carbon black and ruthenium oxide is supported on the surfaces of carbon black and palladium.
  • Example 6 The anode catalyst produced in Example 1 was heat-treated at 300 ° C. for 1 hour in an argon atmosphere containing 3% hydrogen to reduce a part of ruthenium oxide to metal ruthenium, and palladium / ruthenium / carbon black according to this example was obtained. A catalyst was obtained.
  • Table 1 shows the results of analyzing the compositions of the catalysts of Examples 1 to 5 and Comparative Examples 1 to 3 by energy dispersive X-ray analysis (EDX).
  • Table 2 shows the results of evaluating the methanol oxidation activity of these catalysts in the alkaline electrolyte.
  • the evaluation method of methanol oxidation activity was as follows. First, the catalyst was applied to a glass electrode made of glassy carbon, and this was used as a working electrode. Further, in a 60 ° C.
  • RHE reversible hydrogen standard electrode
  • the catalytic activity was evaluated by reading the current per metal weight (mg) at 0.5 V when the potential was swept up to 5 mV / s. At this time, it can be determined that the greater the current, the higher the methanol oxidation activity.
  • the catalyst having high methanol oxidation activity in this evaluation is an anode catalyst combined with an anion exchange type solid polymer electrolyte membrane that conducts hydroxide ions.
  • a fuel cell membrane / electrode assembly having a high power density can be realized.
  • FIG. 8 shows the relationship between the composition of ruthenium in the palladium / ruthenium oxide catalyst and the methanol oxidation activity.
  • FIG. 9 shows the results of analyzing the Ru3d spectra of the catalyst of Example 1 and the catalyst of Example 6 by XPS. Compared with the catalyst of Example 1, the peak of Example 6 was shifted to the low energy side, and there were many metal components of ruthenium. Table 3 shows the result of quantitative analysis of each component of the spectrum of FIG. 9 by peak separation. In the catalyst of Example 1, no metal ruthenium component was found, whereas in the catalyst of Example 6, 32 atomic% of metal ruthenium was present.
  • Example 1 in which all ruthenium was in an oxide state showed higher methanol oxidation activity. From this, it is understood that the ruthenium oxide contained in the ruthenium oxide is preferably as little as possible, and the higher the ruthenium oxide, the higher the methanol oxidation activity.
  • Evaluation 2 The methanol oxidation activity of the catalyst of Example 1 and the catalyst of Comparative Example 3 in the acid electrolyte was evaluated. Evaluation was the same as Evaluation 1 except that an electrolyte solution containing 0.5 mol / L sulfuric acid and 1.0 mol / L methanol was used. Table 5 shows current values per metal weight (mg) at 0.6 V in the obtained results.
  • the methanol oxidation activity of the catalyst of Example 1 was lower than that of the platinum catalyst of Comparative Example 3 in the acid electrolyte. Therefore, it can be seen that the catalyst of Example 1 exhibits a higher activity than the platinum catalyst when combined with an alkaline electrolyte, that is, an anion exchange type solid polymer electrolyte membrane that conducts hydroxide ions.
  • high power density can be realized by including the catalyst according to the present embodiment in the anode of the fuel cell membrane / electrode assembly using the anion exchange type solid polymer electrolyte membrane.
  • FIG. 10 is a developed perspective view of a fuel cell using a methanol aqueous solution as a fuel according to the present embodiment.
  • a fuel cell membrane / electrode assembly 7 in which the diffusion layer 6 is disposed on both surfaces is sandwiched between a pair of separators 101 in which gas flow paths are formed to constitute one fuel cell (unit cell).
  • a plurality of the unit cells are stacked, and a fuel cell is configured by tightening using a current collector plate 8, an insulating plate 9, and an end plate 10 connected to an external circuit.
  • the fuel cell membrane / electrode assembly 7, the separator 101, the current collector plate 8, the insulating plate 9, and the end plate 10 are formed with a manifold 4 serving as an inlet / outlet port of fuel, oxidant gas, and cooling water.
  • Fuel and oxidant gas are supplied from the manifold 4, and electricity is generated by supplying fuel to the anode and oxidant gas to the cathode through the gas flow path of the separator 101.
  • the waste liquid containing unreacted fuel passes through the gas flow path of the separator 101 and is discharged from the outlet-side manifold 4 to the outside.
  • the separator 101 has a flat periphery and is formed by extruding the center part and press-molding to form a flow path.
  • the flow path part is an uneven groove for allowing reaction gas (generic name for fuel gas and oxidant gas) and cooling water to flow through the front and back of the separator.
  • Two gaskets are in close contact with each other on the front and back surfaces of the separator 101, and the reaction gas on the front and back surfaces of the separator 101 is sealed by the gasket so as not to mix.
  • the separator 101 is composed of two types, a separator 101A with a gasket for allowing reaction gas to flow on both sides, and a separator 101B for reaction gas on one side and a cooling water separator 101B on the other side.
  • the cooling water supplied from the manifold 4 flows through the separator in which the cooling water flow path is formed, and serves as a cooling unit for cooling so that the temperature of the unit cell is within a predetermined temperature range.
  • a high power density is realized by including the catalyst according to this example in the anode of the fuel cell membrane / electrode assembly using the anion exchange type solid polymer electrolyte membrane. can do.
  • a liquid containing an organic substance can be used, but it is preferable to use methanol or ethanol as the organic substance.
  • Methanol has a high energy density and can be easily oxidized up to carbon dioxide, and hardly produces a reaction byproduct.
  • ethanol is preferable because it has a high energy density like methanol and is safer than methanol.
  • byproducts such as acetic acid and acetaldehyde are likely to be generated.
  • the organic substance contained in the fuel is methanol or ethanol can be selected from characteristics desired by the application destination of the fuel cell.
  • FIG. 1 This portable information terminal has a foldable structure in which two parts are connected by a hinge 117 that also serves as a holder for the fuel cartridge 116.
  • One portion includes a display device 111 in which a touch panel type input device is integrated and a portion in which an antenna 112 is incorporated.
  • One part includes a fuel cell 113, a processor, a volatile and nonvolatile memory, a power control unit, a fuel cell and secondary battery hybrid control, a main board 114 on which an electronic device and an electronic circuit such as a fuel monitor are mounted, a lithium ion secondary It has a portion on which a battery 115 is mounted.
  • the portable information terminal thus obtained has a high output density of the fuel cell, and thus can be configured to be small and lightweight.

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Abstract

The purpose of the present invention is to provide a high-performance membrane/electrode assembly for fuel cells, which is applicable to a membrane/electrode assembly for fuel cells using an anion exchange solid polymer electrolyte membrane, and wherein the anode is provided with a low-cost catalyst that has higher catalytic activity than platinum. A membrane/electrode assembly, which is provided with an anode that oxidizes a fuel, a cathode that reduces oxygen, and an anion exchange solid polymer electrolyte membrane that is arranged between the anode and the cathode, and which is characterized in that the anode contains palladium and ruthenium oxide.

Description

膜／電極接合体、およびこれを用いた燃料電池Membrane / electrode assembly and fuel cell using the same
　本発明は、電極と電解質膜を接合した膜／電極接合体、およびこれを用いた燃料電池に関する。 The present invention relates to a membrane / electrode assembly in which an electrode and an electrolyte membrane are joined, and a fuel cell using the membrane / electrode assembly.
　最近の電子技術の進歩によって、情報量が増加し、その増加した情報を、より高速に、より高機能に処理する必要があるため、高出力密度で高エネルギー密度の電源、すなわち、連続駆動時間の長い電源を必要とする。 Recent advances in electronic technology increase the amount of information, and it is necessary to process the increased information faster and with higher functionality, so a high power density and high energy density power supply, that is, continuous drive time Need a long power supply.
　充電を必要としない小型発電機、即ち、容易に燃料補給ができるマイクロ発電機の必要性が高まっている。こうした背景から、燃料電池の重要性が検討されている。 Demand for small generators that do not require charging, that is, micro generators that can be easily refueled, is increasing. Against this background, the importance of fuel cells is being studied.
　燃料電池は、少なくとも固体又は液体の電解質及び所望の電気化学反応を誘起する二個の電極、アノード及びカソードから構成され、その燃料が持つ化学エネルギーを直接電気エネルギーに高効率で変換する発電機である。 A fuel cell is a generator that consists of at least a solid or liquid electrolyte and two electrodes that induce a desired electrochemical reaction, an anode and a cathode, and converts the chemical energy of the fuel directly into electrical energy with high efficiency. is there.
　こうした燃料電池は、電解質にカチオン交換型の固体高分子電解質膜を用い、水素を燃料とするものは固体高分子形燃料電池（ＰＥＦＣ：Polymer Electrolyte Fuel Cell）と呼ばれ、メタノールを燃料とするものは直接メタノール形燃料電池（ＤＭＦＣ：Direct Methanol Fuel Cell）、エタノールを燃料とするものは直接エタノール形燃料電池（ＤＥＦＣ：Direct Ethanol Fuel Cell）と呼ばれる。中でも、液体燃料を使用するＤＭＦＣ、ＤＥＦＣは燃料の体積エネルギー密度が高いために、小型の可搬型又は携帯型の電源に有効なものとして注目されている。ＤＭＦＣにおいては、アノードに供給されたメタノールが酸化され、生じた水素イオンがカソードに運ばれ、酸素の還元反応に加わり、水を生じる（式１～３）。
　　アノード反応：ＣＨ3ＯＨ＋Ｈ2Ｏ→ＣＯ2＋６Ｈ+＋６ｅ-　　　…（式１）
　　カソード反応：Ｏ2＋４Ｈ+＋４ｅ-→２Ｈ2Ｏ　　　　　　　　 …（式２）
　　トータル反応：ＣＨ3ＯＨ＋３／２Ｏ2→ＣＯ2＋２Ｈ2Ｏ　　　 …（式３） Such a fuel cell uses a cation exchange type solid polymer electrolyte membrane as an electrolyte, and a fuel cell using hydrogen as a fuel is called a polymer electrolyte fuel cell (PEFC), which uses methanol as fuel. Is called a direct methanol fuel cell (DMFC), and a fuel using ethanol as a fuel is called a direct ethanol fuel cell (DEFC). Among them, DMFCs and DEFCs using liquid fuels are attracting attention as effective for small portable or portable power sources because of their high volumetric energy density. In DMFC, methanol supplied to the anode is oxidized, and the generated hydrogen ions are carried to the cathode and participate in the oxygen reduction reaction to generate water (formulas 1 to 3).
Anode reaction: CH 3 OH + H 2 O → CO 2 + 6H + + 6e − (Formula 1)
Cathode reaction: O 2 + 4H + + 4e − → 2H 2 O (Formula 2)
Total reaction: CH 3 OH + 3 / 2O 2 → CO 2 + 2H 2 O (Formula 3)
　このようなカチオン交換型電解質膜を用いた燃料電池では、アノードの雰囲気は酸性となる。ここで、メタノールの酸化を促す触媒としては、メタノールの酸化活性に優れた白金、あるいは白金－ルテニウムが用いられている。 In a fuel cell using such a cation exchange electrolyte membrane, the anode atmosphere is acidic. Here, platinum or platinum-ruthenium which is excellent in methanol oxidation activity is used as a catalyst for promoting methanol oxidation.
　また、特許文献１に記載のようにアニオン交換型の固体高分子電解質膜を用いた燃料電池がある。アニオン交換型の固体高分子電解質膜を用いたメタノールを燃料とする燃料電池においては、カソードで酸素と水が反応し、生じた水酸化物イオンがアノードに運ばれ、メタノールの酸化反応に加わり、二酸化炭素と水が生じる（式４～６）。
　　アノード反応：ＣＨ3ＯＨ＋６ＯＨ-→ＣＯ2＋５Ｈ2Ｏ＋６ｅ-　…（式４）
　　カソード反応：Ｏ2＋２Ｈ2Ｏ＋４ｅ-→４ＯＨ-　　　　　　　 …（式５）
　　トータル反応：ＣＨ3ＯＨ＋３／２Ｏ2→ＣＯ2＋２Ｈ2Ｏ　　　 …（式６） Further, as described in Patent Document 1, there is a fuel cell using an anion exchange type solid polymer electrolyte membrane. In a fuel cell fueled with methanol using an anion exchange type solid polymer electrolyte membrane, oxygen reacts with water at the cathode, and the resulting hydroxide ions are transported to the anode and participate in the methanol oxidation reaction. Carbon dioxide and water are produced (Equations 4-6).
Anode reaction: CH 3 OH + 6OH − → CO 2 + 5H 2 O + 6e − (Formula 4)
Cathode reaction: O 2 + 2H 2 O + 4e − → 4OH − (Formula 5)
Total reaction: CH 3 OH + 3 / 2O 2 → CO 2 + 2H 2 O (Formula 6)
　このようなアニオン交換型固体高分子電解質膜を用いた燃料電池では、アノードの雰囲気はアルカリ性となる。ここで、メタノールの酸化を促す触媒としては、白金、およびその化合物（白金－ルテニウム、白金－ルテニウム－モリブデン、白金－スズ）が用いられている。 In the fuel cell using such an anion exchange type solid polymer electrolyte membrane, the atmosphere of the anode is alkaline. Here, platinum and its compounds (platinum-ruthenium, platinum-ruthenium-molybdenum, platinum-tin) are used as a catalyst for promoting the oxidation of methanol.
特表２００８－５２７６５８号公報Special table 2008-527658
　アニオン交換型固体高分子電解質を用いたアルカリ形燃料電池は、カチオン交換型電解質を用いる酸形燃料電池のように燃料電池内部が強酸性雰囲気とならない。そのため、触媒に低コストの白金以外の金属を使用することができることで注目されている。しかしながら、白金以外の触媒ではメタノール酸化に要する過電圧は大きく、更に活性の高い触媒が望まれている。 An alkaline fuel cell using an anion exchange type solid polymer electrolyte does not have a strongly acidic atmosphere inside the fuel cell unlike an acid type fuel cell using a cation exchange type electrolyte. For this reason, attention has been paid to the fact that low-cost metals other than platinum can be used for the catalyst. However, a catalyst other than platinum requires a large overvoltage required for methanol oxidation, and a catalyst having higher activity is desired.
　そこで、本発明は、白金よりも触媒活性が高く、安価な触媒をアノードに備えた高性能の燃料電池用膜／電極接合体を提供することを目的とする。 Accordingly, an object of the present invention is to provide a high-performance membrane / electrode assembly for a fuel cell having a catalyst having a higher catalytic activity than platinum and an inexpensive catalyst.
　本発明に係る実施態様のひとつである膜／電極接合体は、燃料を酸化するアノードと、酸素を還元するカソードと、アノードとカソードとの間に配置されるアニオン交換型固体高分子電解質膜とを備える膜／電極接合体において、アノードにパラジウムと、酸化ルテニウムを含ませることを特徴とする。 A membrane / electrode assembly according to one embodiment of the present invention includes an anode for oxidizing fuel, a cathode for reducing oxygen, and an anion exchange type solid polymer electrolyte membrane disposed between the anode and the cathode. In the membrane / electrode assembly provided with Pd, the anode contains palladium and ruthenium oxide.
　更に、アノードに含ませるパラジウムと酸化ルテニウムがカーボン担体に担持されていることを特徴とする。 Furthermore, palladium and ruthenium oxide contained in the anode are supported on a carbon support.
　また、燃料がメタノールを含む水溶液であることを特徴とする。 Further, the fuel is an aqueous solution containing methanol.
　更に、アノードに含まれるパラジウムと、ルテニウムの組成が、８５：１５から３５：６５の範囲であることを特徴とする。 Furthermore, the composition of palladium and ruthenium contained in the anode is in the range of 85:15 to 35:65.
　また、このような膜／電極接合体と、燃料を供給する部材と、酸素を供給する部材と、集電用部材とを用いて燃料電池とすることができる。また、この燃料電池を搭載した燃料電池システムとすることも可能である。 Further, a fuel cell can be obtained by using such a membrane / electrode assembly, a member for supplying fuel, a member for supplying oxygen, and a member for current collection. It is also possible to provide a fuel cell system equipped with this fuel cell.
　燃料はアノードにおいて電気化学的に酸化され、カソードでは酸素が還元され、両電極間には電気的なポテンシャルの差が生じる。このときに外部回路として負荷が両電極間にかけられると、電解質中に水酸化物イオンの移動が生起し、外部負荷には電気エネルギーが取り出される。 Fuel is electrochemically oxidized at the anode and oxygen is reduced at the cathode, resulting in a difference in electrical potential between the electrodes. At this time, when a load is applied as an external circuit between the two electrodes, hydroxide ions move in the electrolyte, and electric energy is extracted from the external load.
　このために各種の燃料電池は、大型発電システム、小型分散型コージェネレーションシステム、電気自動車電源システム等に期待は高く、実用化開発が活発に展開されている。 For this reason, various fuel cells have high expectations for large power generation systems, small distributed cogeneration systems, electric vehicle power supply systems, and the like, and their practical development is actively being developed.
　本発明によって、出力密度が高く、高価な白金を用いない燃料電池用膜／電極接合体、燃料電池、およびこれを用いた燃料電池システムを提供することができる。 According to the present invention, it is possible to provide a fuel cell membrane / electrode assembly, a fuel cell, and a fuel cell system using the same, which have high output density and do not use expensive platinum.
本実施例に係る燃料電池用膜／電極接合体の断面模式図。The cross-sectional schematic diagram of the membrane / electrode assembly for fuel cells which concerns on a present Example. 本実施例に係るアノードの断面模式図。The cross-sectional schematic diagram of the anode which concerns on a present Example. 本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの断面模式図。The cross-sectional schematic diagram of palladium and ruthenium oxide carry | supported by carbon black which concerns on a present Example. 本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの断面模式図。The cross-sectional schematic diagram of palladium and ruthenium oxide carry | supported by carbon black which concerns on a present Example. 本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの断面模式図。The cross-sectional schematic diagram of palladium and ruthenium oxide carry | supported by carbon black which concerns on a present Example. 本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの断面模式図。The cross-sectional schematic diagram of palladium and ruthenium oxide carry | supported by carbon black which concerns on a present Example. 本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの断面模式図。The cross-sectional schematic diagram of palladium and ruthenium oxide carry | supported by carbon black which concerns on a present Example. 本実施例に係るパラジウム／酸化ルテニウム触媒中のルテニウムの組成とメタノール酸化活性の関係。The relationship between the composition of ruthenium in the palladium / ruthenium oxide catalyst according to this example and the methanol oxidation activity. 本実施例に係る触媒のＲｕ３ｄ結合エネルギー（ＸＰＳ）。Ru3d binding energy (XPS) of the catalyst according to this example. 本実施例に係る燃料電池の展開斜視図。1 is an exploded perspective view of a fuel cell according to the present embodiment. 本実施例に係る燃料電池発電システムの断面模式図。The cross-sectional schematic diagram of the fuel cell power generation system which concerns on a present Example.
　以下に、本実施例の実施の形態を示す。 The following is an embodiment of the present embodiment.
　図１に本実施例に係る燃料電池用膜／電極接合体の断面模式図を示す。アニオン交換型固体高分子電解質膜１１の両面にアノード１２、カソード１３が配置される。また、必ずしも必要ではないが、アノード１２、カソード１３のアニオン交換型固体高分子電解質膜１１とは反対側にアノード拡散層１４、カソード拡散層１５が配置される。アノード１２には有機物を含む液体燃料が供給され、カソード１３には空気などの酸素を含む気体が供給される。ここで、アノード１２には、パラジウムと酸化ルテニウムが触媒として含まれる。このような、アニオン交換型固体高分子電解質膜１１と組み合わせて用いることで、パラジウムと酸化ルテニウム近傍は、水素イオンよりも水酸化物イオンの方が多い環境となり、高い有機物酸化活性を示す。ここで、本実施例が意図するパラジウムとは、金属成分が主体のものであり、水酸化物、酸化物成分が極力少ないものが好ましい。また、酸化ルテニウムとは、水酸化物、酸化物成分が主体のものであり、金属成分が極力少ないものが好ましい。パラジウムと酸化ルテニウムの凝集を防ぎ、比表面積を大きくするため、パラジウムと酸化ルテニウムは触媒担体に担持されていることが好ましい。触媒担体は、良好な電子伝導性と大きな比表面積を有していることが望ましく、例えば、カーボン担体や金属多孔体を用いることができる。比表面積の観点から、カーボン担体が特に好ましく、例えばカーボンブラック、カーボンナノチューブ、メソポーラスカーボン、活性炭などを用いることができる。この際、カーボン担体の比表面積が１０～２０００ｍ2／ｇのものを選択することが好ましい。また、アノード１２には触媒を結着する樹脂を含ませることで、触媒が液体燃料中に脱落することを抑制することができる。結着する樹脂には、例えば、フッ素系樹脂であるポリテトラフルオロエチレンや、炭化水素系樹脂であるポリスチレン、ポリエーテルケトン、ポリエーテルスルホンなどを用いることができる。また、結着する樹脂として、アニオン交換基を備えた固体高分子を用いることで、アニオン交換型固体高分子電解質膜１１を通してカソード１３から供給される水酸化物イオンをパラジウム、酸化ルテニウムまで伝達しやすくなるため好ましい。一方、液体燃料中に水酸化カリウム、水酸化ナトリウム、炭酸カリウム、炭酸ナトリウムなどのアルカリ性化合物を含ませた場合には、これらが水酸化物イオンを伝導するため、結着用樹脂がアニオン交換基を備えていることは必須ではない。アニオン交換基を備えた固体高分子を結着用樹脂として用いる際には、例えば、炭化水素系樹脂にアニオン交換基である第４級アミン基やホスホニウム基を導入したものを用いることができる。また、アニオン交換型固体高分子電解質膜１１においても、特に限定されるものではないが、同様にアニオン交換基である第４級アミン基やホスホニウム基を導入したポリスチレン、ポリエーテルケトン、ポリエーテルスルホンなどを用いることができる。カソード１３に含ませる触媒としては、酸素還元に対する触媒活性を有するものであれば特に限定されるものではないが、例えば、白金、パラジウム、鉄、コバルト、ニッケルや、窒素含有カーボンなどを用いることができ、カーボン担体に担持されているものが好ましい。また、カソード１３にもアノード１２と同様に触媒を結着する樹脂を用いることが好ましい。アノード拡散層１４、カソード拡散層１５にはカーボンペーパーやカーボンクロスなどの多孔質材料を用いることができるが、電子伝導性を有して、燃料や酸素が拡散するための経路が備わっており、燃料電池発電環境下で安定な材料であれば、特に限定されるものではない。 FIG. 1 is a schematic sectional view of a membrane / electrode assembly for a fuel cell according to this example. An anode 12 and a cathode 13 are disposed on both sides of the anion exchange type solid polymer electrolyte membrane 11. Although not necessarily required, the anode diffusion layer 14 and the cathode diffusion layer 15 are disposed on the opposite side of the anode 12 and the cathode 13 from the anion exchange type solid polymer electrolyte membrane 11. A liquid fuel containing an organic substance is supplied to the anode 12, and a gas containing oxygen such as air is supplied to the cathode 13. Here, the anode 12 contains palladium and ruthenium oxide as catalysts. By using in combination with such an anion exchange type solid polymer electrolyte membrane 11, the vicinity of palladium and ruthenium oxide becomes an environment where there are more hydroxide ions than hydrogen ions, and shows high organic matter oxidation activity. Here, the palladium intended by the present embodiment is mainly composed of a metal component, and preferably has a minimum amount of hydroxide and oxide components. Further, ruthenium oxide is mainly composed of hydroxide and oxide components, and preferably has as little metal components as possible. In order to prevent aggregation of palladium and ruthenium oxide and increase the specific surface area, it is preferable that palladium and ruthenium oxide are supported on a catalyst carrier. The catalyst support desirably has good electron conductivity and a large specific surface area. For example, a carbon support or a porous metal body can be used. From the viewpoint of specific surface area, a carbon support is particularly preferable, and for example, carbon black, carbon nanotube, mesoporous carbon, activated carbon, and the like can be used. At this time, it is preferable to select a carbon support having a specific surface area of 10 to 2000 m 2 / g. Further, the anode 12 can be prevented from dropping into the liquid fuel by containing a resin that binds the catalyst. As the resin to be bound, for example, polytetrafluoroethylene, which is a fluorine resin, polystyrene, polyether ketone, polyether sulfone, or the like, which is a hydrocarbon resin, can be used. Further, by using a solid polymer having an anion exchange group as the resin to be bound, hydroxide ions supplied from the cathode 13 through the anion exchange type solid polymer electrolyte membrane 11 are transmitted to palladium and ruthenium oxide. Since it becomes easy, it is preferable. On the other hand, when alkaline compounds such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate are included in the liquid fuel, these conduct hydroxide ions, so that the binding resin has an anion exchange group. It is not essential to have it. When a solid polymer having an anion exchange group is used as a binding resin, for example, a hydrocarbon resin in which a quaternary amine group or a phosphonium group which is an anion exchange group is introduced can be used. The anion exchange type solid polymer electrolyte membrane 11 is not particularly limited, but is similarly polystyrene, polyetherketone, polyethersulfone into which a quaternary amine group or phosphonium group which is an anion exchange group is introduced. Etc. can be used. The catalyst included in the cathode 13 is not particularly limited as long as it has a catalytic activity for oxygen reduction. For example, platinum, palladium, iron, cobalt, nickel, nitrogen-containing carbon, or the like is used. And those supported on a carbon support are preferred. Further, it is preferable to use a resin that binds the catalyst to the cathode 13 as in the case of the anode 12. Porous materials such as carbon paper and carbon cloth can be used for the anode diffusion layer 14 and the cathode diffusion layer 15, but they have electronic conductivity and have a path for fuel and oxygen to diffuse. The material is not particularly limited as long as the material is stable in the fuel cell power generation environment.
　図２に本実施例に係るアノードの断面模式図を示す。アニオン交換型固体高分子電解質膜２１上にアノード２２が形成されている。アノード２２には、パラジウムと酸化ルテニウムが担持されたカーボンブラック２３が樹脂２４で結着されている。ここで、アノード２２に含まれるパラジウムと酸化ルテニウムの量は、特に限定されるものではないが、投影面積に対して０.１mg／cm2以上であることが好ましい。０.１mg／cm2より少ないと、十分な出力密度が得られにくい。また、パラジウムと酸化ルテニウムの量の上限は、特に限定されるものではないが、１０mg／cm2以下であることが好ましい。これ以上、多くのパラジウムと酸化ルテニウムを含ませても、出力密度の向上効果が得られにくいためである。また、カーボンブラックを担体に用いた際のパラジウムと酸化ルテニウムの担持量は、特に限定されるものではないが、カーボンブラック、パラジウム及び酸化ルテニウムの合計に対して１０～８０重量％とすることが好ましい。１０重量％以下とすると、所望のパラジウムと酸化ルテニウムをアノード２２に含ませようとした場合に、アノード２２が厚くなりすぎて有機物を含む液体燃料の拡散性が悪くなる。また、８０重量％以上とするとパラジウムと酸化ルテニウムをカーボンブラック上に担持することが困難になり、担体を用いる利点が少なくなる。 FIG. 2 is a schematic cross-sectional view of the anode according to this example. An anode 22 is formed on the anion exchange type solid polymer electrolyte membrane 21. A carbon black 23 carrying palladium and ruthenium oxide is bound to the anode 22 by a resin 24. Here, the amount of palladium and ruthenium oxide contained in the anode 22 is not particularly limited, but is preferably 0.1 mg / cm 2 or more with respect to the projected area. When the amount is less than 0.1 mg / cm 2 , it is difficult to obtain a sufficient output density. The upper limit of the amount of palladium and ruthenium oxide is not particularly limited, but is preferably 10 mg / cm 2 or less. This is because the effect of improving the output density is hardly obtained even if more palladium and ruthenium oxide are included. The amount of palladium and ruthenium oxide supported when carbon black is used as a carrier is not particularly limited, but may be 10 to 80% by weight based on the total of carbon black, palladium and ruthenium oxide. preferable. If it is 10 wt% or less, when the desired palladium and ruthenium oxide are to be included in the anode 22, the anode 22 becomes too thick and the diffusibility of the liquid fuel containing organic matter becomes worse. On the other hand, if it is 80% by weight or more, it becomes difficult to support palladium and ruthenium oxide on carbon black, and the advantage of using a carrier is reduced.
　ここで、アノード２２をアニオン交換型固体高分子電解質膜２１上に形成する方法としては、例えば、パラジウムと酸化ルテニウムを担持したカーボンブラック２３を、樹脂２４を含むアルコール溶液と混合し、アニオン交換型固体高分子電解質膜２１上にスプレー塗布する方法を用いることができる。 Here, as a method for forming the anode 22 on the anion exchange type solid polymer electrolyte membrane 21, for example, carbon black 23 carrying palladium and ruthenium oxide is mixed with an alcohol solution containing a resin 24, and an anion exchange type is then performed. A method of spray coating on the solid polymer electrolyte membrane 21 can be used.
　図３に本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの断面模式図を示す。カーボンブラック３１の表面に酸化ルテニウム３３が層状に担持され、酸化ルテニウム３３の上にパラジウム３２が担持されている。図４に本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの別の形態の断面模式図を示す。カーボンブラック３１の表面にパラジウム３２が層状に担持され、パラジウム３２の上に酸化ルテニウム３３が担持されている。図５に本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの別の形態の断面模式図を示す。カーボンブラック３１の表面に酸化ルテニウム３３が担持され、酸化ルテニウム３３の上にパラジウム３２が担持されている。ここで、パラジウム３２はできるだけ酸化ルテニウム３３に担持されていることが好ましいが、カーボンブラック３１に直接担持されていても妨げとはならない。図６に本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの別の形態の断面模式図を示す。カーボンブラック３１の表面にパラジウム３２が担持され、パラジウム３２の上に酸化ルテニウム３３が担持されている。ここで、酸化ルテニウム３３はできるだけパラジウム３２に担持されていることが好ましいが、カーボンブラック３１に直接担持されていても妨げとはならない。図７に本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムの別の形態の断面模式図を示す。カーボンブラック３１の表面にパラジウム３２と酸化ルテニウム３３が担持されている。ここで、パラジウム３２と酸化ルテニウム３３はできるだけ接していることが好ましいが、それぞれ、孤立していても妨げとはならない。本実施例に係るカーボンブラックに担持されたパラジウムと酸化ルテニウムにおいては、できるだけ、パラジウムと酸化ルテニウムの界面が多く形成されるようにすることが好ましい。このようにすることで、高い有機物の酸化活性を実現することができる。 FIG. 3 shows a schematic cross-sectional view of palladium and ruthenium oxide supported on carbon black according to this example. Ruthenium oxide 33 is supported on the surface of the carbon black 31 in layers, and palladium 32 is supported on the ruthenium oxide 33. FIG. 4 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example. Palladium 32 is supported on the surface of the carbon black 31 in layers, and ruthenium oxide 33 is supported on the palladium 32. FIG. 5 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example. Ruthenium oxide 33 is supported on the surface of the carbon black 31, and palladium 32 is supported on the ruthenium oxide 33. Here, it is preferable that the palladium 32 is supported on the ruthenium oxide 33 as much as possible, but even if it is directly supported on the carbon black 31, it does not interfere. FIG. 6 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example. Palladium 32 is supported on the surface of the carbon black 31, and ruthenium oxide 33 is supported on the palladium 32. Here, the ruthenium oxide 33 is preferably supported on the palladium 32 as much as possible, but even if it is directly supported on the carbon black 31, it does not interfere. FIG. 7 shows a schematic cross-sectional view of another form of palladium and ruthenium oxide supported on carbon black according to this example. Palladium 32 and ruthenium oxide 33 are supported on the surface of the carbon black 31. Here, it is preferable that the palladium 32 and the ruthenium oxide 33 are in contact with each other as much as possible. In the palladium and ruthenium oxide supported on the carbon black according to the present embodiment, it is preferable that as many interfaces as possible are formed between the palladium and ruthenium oxide. By doing in this way, high organic substance oxidation activity can be realized.
　酸化ルテニウム３３を担持する方法としては、カーボンブラック３１を分散させた水に、ルテニウム化合物を溶解させ、これを攪拌しながらアルカリ性物質を添加してｐＨを３以上に増加させることで酸化ルテニウムとして担持することができる。ここで、ルテニウム化合物としては、例えば、塩化ルテニウム、ヘキサアンミンルテニウム塩化物などを用いることができる。また、ｐＨを調整するアルカリ性物質としては、水酸化カリウム、水酸化ナトリウムなどを用いることができる。その後、パラジウム３２を担持する方法としては、酸化ルテニウム３３を担持したカーボンブラック３１を水に分散させ、パラジウム化合物と還元剤を含む水溶液を添加し、加熱することで、パラジウム化合物を金属パラジウムとして還元析出させて、担持することができる。ここで、パラジウム化合物としては、塩化パラジウム、硝酸パラジウム、ジニトロジアミンパラジウムなどを用いることができ、還元剤としては、次亜リン酸、亜リン酸、水素化ホウ素ナトリウム、ホルムアルデヒドなどを用いることができる。ここでは、酸化ルテニウムを担持した後、パラジウムを担持する方法を説明したが、同様の手法で、先にパラジウムを担持した後、酸化ルテニウムを担持すればパラジウム上に酸化ルテニウムが担持された形態とすることができる。 The ruthenium oxide 33 is supported as a ruthenium oxide by dissolving a ruthenium compound in water in which carbon black 31 is dispersed and adding an alkaline substance while stirring the compound to increase the pH to 3 or more. can do. Here, as the ruthenium compound, for example, ruthenium chloride, hexaammineruthenium chloride or the like can be used. Moreover, potassium hydroxide, sodium hydroxide, etc. can be used as an alkaline substance which adjusts pH. Thereafter, palladium 32 is supported by dispersing carbon black 31 supporting ruthenium oxide 33 in water, adding an aqueous solution containing a palladium compound and a reducing agent, and heating to reduce the palladium compound as metallic palladium. It can be deposited and supported. Here, palladium chloride, palladium nitrate, dinitrodiamine palladium and the like can be used as the palladium compound, and hypophosphorous acid, phosphorous acid, sodium borohydride, formaldehyde and the like can be used as the reducing agent. . Here, the method of supporting palladium after supporting ruthenium oxide has been described, but in the same manner, after supporting palladium first, and then supporting ruthenium oxide, ruthenium oxide is supported on palladium. can do.
　ここで、特にルテニウムは酸化物状態で用いることが必要であり、金属状態であると触媒活性が低下してしまう。したがって、触媒を合成する際、あるいは合成した後、水素を含む還元雰囲気で熱処理することは酸化ルテニウムを金属へ還元してしまうため、望ましくない。また、パラジウムとルテニウムを合金化してしまうと、ルテニウムは金属状態となってしまうため、望ましくない。酸化ルテニウムの状態としては、ＲｕＯ2、ＲｕＯ3、ＲｕＯ4などが挙げられ、金属状態のルテニウムが極力少ないことが好ましく、金属状態のルテニウムを１０原子％以下とすることが好ましい。ルテニウムの状態は、例えば、ＸＰＳで分析することができ、Ｒｕ３ｄスペクトルをピーク分離することで定量することができる。なお、金属Ｒｕ、ＲｕＯ2、ＲｕＯ3、ＲｕＯ4はそれぞれ、２８０.１、２８０.７、２８２.５、２８３.３ｅＶ近辺にピークが表れる。また、パラジウムの状態は特に限定されるものではないが、金属状態のパラジウムが多く存在していることが好ましい。なお、パラジウムの状態も同様にＸＰＳで分析することが可能であり、金属Ｐｄ、ＰｄＯ、ＰｄＯ2、はそれぞれ、３３５.２、３３６.３、３３７.９ｅＶ近辺にピークが表れる。 Here, in particular, ruthenium needs to be used in an oxide state, and if it is in a metal state, the catalytic activity is lowered. Accordingly, when synthesizing the catalyst or after the synthesis, heat treatment in a reducing atmosphere containing hydrogen is not desirable because ruthenium oxide is reduced to a metal. Further, when palladium and ruthenium are alloyed, ruthenium is in a metallic state, which is not desirable. The state of the ruthenium oxide, RuO 2, RuO 3, such as RuO 4 and the like, it is preferably as low as possible ruthenium metal state, ruthenium in a metal state is preferably 10 atomic% or less. The state of ruthenium can be analyzed by XPS, for example, and can be quantified by separating the Ru3d spectrum into peaks. Note that peaks of metals Ru, RuO 2 , RuO 3 , and RuO 4 appear in the vicinity of 280.1, 280.7, 282.5, and 283.3 eV, respectively. Moreover, although the state of palladium is not particularly limited, it is preferable that a large amount of palladium in the metal state is present. Similarly, the state of palladium can be analyzed by XPS, and the peaks of metals Pd, PdO, and PdO 2 appear around 335.2, 336.3, 337.9 eV, respectively.
　ここで、パラジウムと酸化ルテニウムに含まれるルテニウムの組成比は、パラジウム：ルテニウム＝８５：１５～３０：７０の範囲とすることが好ましい。このような組成とすることで、単独金属で最も活性が高いと言われている白金触媒よりも高い有機物の酸化活性を得ることができる。好ましくは、パラジウム：ルテニウム＝７０：３０～４５：５５の範囲であり、更に好ましくは、パラジウム：ルテニウム＝６５：３５～５０：５０の範囲である。この範囲とすることで白金触媒の４倍以上の有機物の酸化活性を得ることができる。もちろん、パラジウム単独、あるいは酸化ルテニウム単独では高い活性を得ることはできない。 Here, the composition ratio of ruthenium contained in palladium and ruthenium oxide is preferably in the range of palladium: ruthenium = 85: 15 to 30:70. By setting it as such a composition, the oxidation activity of organic substance higher than the platinum catalyst said to be the most active with a single metal can be obtained. Preferably, the range is palladium: ruthenium = 70: 30 to 45:55, and more preferably the range is palladium: ruthenium = 65: 35 to 50:50. By setting it as this range, the oxidation activity of the organic substance 4 times or more of the platinum catalyst can be obtained. Of course, high activity cannot be obtained with palladium alone or ruthenium oxide alone.
　以下、本実施例に係る燃料電池用膜／電極接合体の実施態様を具体的に説明する。 Hereinafter, embodiments of the membrane / electrode assembly for a fuel cell according to this example will be described in detail.
（実施例１）
　カーボンブラック１.０ｇと、０.６６ｇのＲｕＣｌ3と、１０００mlの純水を混合し、攪拌しながら、１ｍｏｌ／Ｌの水酸化ナトリウム水溶液を徐々に滴下して、ｐＨを４に保持して、酸化ルテニウムをカーボンブラック上に担持した。その後、反応溶液をろ過、純水で良く洗浄した後、大気中、８０℃で乾燥した。次に、得られた粉末と、０.５７ｇのＰｄＣｌ2と、０.４８ｇのホルムアルデヒドと、１０００mlの純水を混合し、昇温、攪拌しながら、１ｍｏｌ／Ｌの水酸化ナトリウム水溶液を徐々に滴下することでｐＨを８に保持し、酸化ルテニウムが担持されたカーボンブラック上にパラジウムを還元、析出させ、担持した。その後、反応溶液をろ過、純水で良く洗浄した後、大気中、８０℃で乾燥し、本実施例に係るカーボンブラックにパラジウムと酸化ルテニウムが担持されたアノード触媒を得た。本実施例で得られたアノード触媒は、カーボンブラック上に酸化ルテニウムが担持され、カーボンブラックおよび酸化ルテニウムの表面にパラジウムが担持された形態である。 Example 1
Carbon black (1.0 g), 0.66 g (RuCl 3) , and 1000 ml of pure water were mixed, and while stirring, a 1 mol / L sodium hydroxide aqueous solution was gradually added dropwise to maintain the pH at 4. Ruthenium oxide was supported on carbon black. Thereafter, the reaction solution was filtered, thoroughly washed with pure water, and then dried at 80 ° C. in the air. Next, the powder obtained, 0.57 g of PdCl 2 , 0.48 g of formaldehyde, and 1000 ml of pure water were mixed, and while heating and stirring, a 1 mol / L sodium hydroxide aqueous solution was gradually added. By dropping, the pH was maintained at 8, and palladium was reduced and deposited on the carbon black on which ruthenium oxide was supported and supported. Thereafter, the reaction solution was filtered and thoroughly washed with pure water, and then dried at 80 ° C. in the air to obtain an anode catalyst in which palladium and ruthenium oxide were supported on carbon black according to this example. The anode catalyst obtained in this example has a form in which ruthenium oxide is supported on carbon black and palladium is supported on the surfaces of carbon black and ruthenium oxide.
（実施例２）
　用いるＲｕＣｌ3と、ＰｄＣｌ2の重量をそれぞれ、０.３３ｇ、０.８４ｇとした以外は実施例１と同様にして、本実施例に係るカーボンブラックにパラジウムと酸化ルテニウムが担持されたアノード触媒を得た。本実施例で得られたアノード触媒は、カーボンブラック上に酸化ルテニウムが担持され、カーボンブラックおよび酸化ルテニウムの表面にパラジウムが担持された形態である。 (Example 2)
In the same manner as in Example 1 except that the weights of RuCl 3 and PdCl 2 used were 0.33 g and 0.84 g, respectively, an anode catalyst having palladium and ruthenium oxide supported on carbon black according to this example was used. Obtained. The anode catalyst obtained in this example has a form in which ruthenium oxide is supported on carbon black and palladium is supported on the surfaces of carbon black and ruthenium oxide.
（実施例３）
　用いるＲｕＣｌ3と、ＰｄＣｌ2の重量をそれぞれ、１.０１ｇ、０.２９ｇとした以外は実施例１と同様にして、本実施例に係るカーボンブラックにパラジウムと酸化ルテニウムが担持されたアノード触媒を得た。本実施例で得られたアノード触媒は、カーボンブラック上に酸化ルテニウムが担持され、カーボンブラックおよび酸化ルテニウムの表面にパラジウムが担持された形態である。 (Example 3)
An anode catalyst in which palladium and ruthenium oxide were supported on carbon black according to this example was prepared in the same manner as in Example 1 except that the weights of RuCl 3 and PdCl 2 used were 1.01 g and 0.29 g, respectively. Obtained. The anode catalyst obtained in this example has a form in which ruthenium oxide is supported on carbon black and palladium is supported on the surfaces of carbon black and ruthenium oxide.
（実施例４）
　カーボンブラック１.０ｇと、０.５７ｇのＰｄＣｌ2と、０.４８ｇのホルムアルデヒドと、１０００mlの純水を混合し、昇温、攪拌しながら、１ｍｏｌ／Ｌの水酸化ナトリウム水溶液を徐々に滴下することでｐＨを８に保持することで、パラジウムをカーボンブラック上に担持した。その後、反応溶液をろ過、純水で良く洗浄した後、大気中、８０℃で乾燥した。次に、得られた粉末と、０.６６ｇのＲｕＣｌ3と、１０００mlの純水を混合し、攪拌しながら、１ｍｏｌ／Ｌの水酸化ナトリウム水溶液を徐々に滴下して、ｐＨ４に保持して、酸化ルテニウムをパラジウムが担持されたカーボンブラック上に担持した。その後、反応溶液をろ過、純水で良く洗浄した後、大気中、８０℃で乾燥し、本実施例に係るカーボンブラックにパラジウムと酸化ルテニウムが担持されたアノード触媒を得た。本実施例で得られたアノード触媒は、カーボンブラック上にパラジウムが担持され、カーボンブラックおよびパラジウムの表面に酸化ルテニウムが担持された形態である。 (Example 4)
Carbon black (1.0 g), 0.57 g of PdCl 2 , 0.48 g of formaldehyde, and 1000 ml of pure water are mixed, and a 1 mol / L aqueous sodium hydroxide solution is gradually added dropwise while heating and stirring. By keeping the pH at 8, the palladium was supported on the carbon black. Thereafter, the reaction solution was filtered, thoroughly washed with pure water, and then dried at 80 ° C. in the air. Next, the obtained powder, 0.66 g of RuCl 3 and 1000 ml of pure water were mixed, and while stirring, a 1 mol / L aqueous sodium hydroxide solution was gradually added dropwise to maintain the pH at 4. Ruthenium oxide was supported on carbon black on which palladium was supported. Thereafter, the reaction solution was filtered and thoroughly washed with pure water, and then dried at 80 ° C. in the air to obtain an anode catalyst in which palladium and ruthenium oxide were supported on carbon black according to this example. The anode catalyst obtained in this example has a form in which palladium is supported on carbon black and ruthenium oxide is supported on the surfaces of carbon black and palladium.
（実施例５）
　用いるＰｄＣｌ2と、ＲｕＣｌ3の重量をそれぞれ、０.８４ｇ、０.３３ｇとした以外は実施例５と同様にして、本実施例に係るカーボンブラックにパラジウムと酸化ルテニウムが担持されたアノード触媒を得た。本実施例で得られたアノード触媒は、カーボンブラック上にパラジウムが担持され、カーボンブラックおよびパラジウムの表面に酸化ルテニウムが担持された形態である。 (Example 5)
An anode catalyst in which palladium and ruthenium oxide were supported on carbon black according to this example was prepared in the same manner as in Example 5 except that the weights of PdCl 2 and RuCl 3 used were 0.84 g and 0.33 g, respectively. Obtained. The anode catalyst obtained in this example has a form in which palladium is supported on carbon black and ruthenium oxide is supported on the surfaces of carbon black and palladium.
（実施例６）
　実施例１で作製したアノード触媒を、３％水素を含むアルゴン雰囲気で３００℃、１時間熱処理することで酸化ルテニウムの一部を金属ルテニウムに還元し、本実施例に係るパラジウム／ルテニウム／カーボンブラック触媒を得た。 (Example 6)
The anode catalyst produced in Example 1 was heat-treated at 300 ° C. for 1 hour in an argon atmosphere containing 3% hydrogen to reduce a part of ruthenium oxide to metal ruthenium, and palladium / ruthenium / carbon black according to this example was obtained. A catalyst was obtained.
（比較例１）
　カーボンブラック１.０ｇと、１.１１ｇのＰｄＣｌ2と、０.４８ｇのホルムアルデヒドと、１０００mlの純水を混合し、昇温、攪拌しながら、１ｍｏｌ／Ｌの水酸化ナトリウム水溶液を徐々に滴下することでｐＨを８に保持し、酸化ルテニウムが担持されたカーボンブラック上にパラジウムを還元、析出させ、担持した。その後、反応溶液をろ過、純水で良く洗浄した後、大気中、８０℃で乾燥し、本比較例に係るパラジウム／カーボンブラック触媒を得た。 (Comparative Example 1)
Carbon black (1.0 g), 1.11 g of PdCl 2 , 0.48 g of formaldehyde and 1000 ml of pure water are mixed, and a 1 mol / L sodium hydroxide aqueous solution is gradually added dropwise while heating and stirring. Thus, the pH was maintained at 8, and palladium was reduced and deposited on the carbon black on which ruthenium oxide was supported, and supported. Thereafter, the reaction solution was filtered, thoroughly washed with pure water, and then dried at 80 ° C. in the air to obtain a palladium / carbon black catalyst according to this comparative example.
（比較例２）
　カーボンブラック１.０ｇと、１.３７ｇのＲｕＣｌ3と、１０００mlの純水を混合し、攪拌しながら、１ｍｏｌ／Ｌの水酸化ナトリウム水溶液を徐々に滴下して、ｐＨを４に保持して、酸化ルテニウムをカーボンブラック上に担持した。その後、反応溶液をろ過、純水で良く洗浄した後、大気中、８０℃で乾燥することで、本比較例に係る酸化ルテニウム／カーボンブラック触媒を得た。 (Comparative Example 2)
Carbon black 1.0g, 1.37g RuCl 3 and 1000ml pure water were mixed, and while stirring, 1mol / L sodium hydroxide aqueous solution was gradually added dropwise to maintain pH at 4. Ruthenium oxide was supported on carbon black. Thereafter, the reaction solution was filtered, thoroughly washed with pure water, and then dried at 80 ° C. in the air to obtain a ruthenium oxide / carbon black catalyst according to this comparative example.
（比較例３）
　カーボンブラックに白金が担持された触媒を、本比較例に係る白金／カーボンブラック触媒とした。 (Comparative Example 3)
A catalyst in which platinum was supported on carbon black was used as a platinum / carbon black catalyst according to this comparative example.
（評価１）
　実施例１～５、比較例１～３の触媒の組成をエネルギー分散型Ｘ線分析（ＥＤＸ）で分析した結果を表１に示す。また、これらの触媒のアルカリ電解質中でのメタノール酸化活性を評価した結果を表２に示す。メタノール酸化活性の評価方法は次のとおりとした。まず、触媒をグラッシーカーボン製のディスク電極に塗布して、これを作用極とした。また、可逆水素基準電極（ＲＨＥ）を参照電極とし、白金線を対極として、０.１ｍｏｌ／Ｌの水酸化カリウムと１ｍｏｌ／Ｌのメタノールを含む６０℃の電解質水溶液中で、０～１.２Ｖまで５ｍＶ／ｓで電位を掃引した際に、０.５Ｖ時の金属重量（mg）当たりの電流を読み取ることで触媒活性を評価した。この際、前記の電流が多いほど、メタノール酸化活性が高いと判断できる。また、本評価では電解質水溶液は水酸化物イオンを多く含んでいるため、本評価でメタノール酸化活性が高い触媒は、水酸化物イオンを伝導するアニオン交換型固体高分子電解質膜と組み合わせたアノード触媒とすることで、高い出力密度を持つ燃料電池用膜／電極接合体を実現することができるものである。 (Evaluation 1)
Table 1 shows the results of analyzing the compositions of the catalysts of Examples 1 to 5 and Comparative Examples 1 to 3 by energy dispersive X-ray analysis (EDX). Table 2 shows the results of evaluating the methanol oxidation activity of these catalysts in the alkaline electrolyte. The evaluation method of methanol oxidation activity was as follows. First, the catalyst was applied to a glass electrode made of glassy carbon, and this was used as a working electrode. Further, in a 60 ° C. aqueous electrolyte solution containing 0.1 mol / L potassium hydroxide and 1 mol / L methanol using a reversible hydrogen standard electrode (RHE) as a reference electrode and a platinum wire as a counter electrode, 0 to 1.2 V The catalytic activity was evaluated by reading the current per metal weight (mg) at 0.5 V when the potential was swept up to 5 mV / s. At this time, it can be determined that the greater the current, the higher the methanol oxidation activity. In this evaluation, since the aqueous electrolyte solution contains a large amount of hydroxide ions, the catalyst having high methanol oxidation activity in this evaluation is an anode catalyst combined with an anion exchange type solid polymer electrolyte membrane that conducts hydroxide ions. Thus, a fuel cell membrane / electrode assembly having a high power density can be realized.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２の結果から分かるように実施例１～５の触媒は比較例３の白金触媒よりも高い触媒活性を示した。また、パラジウム／酸化ルテニウム触媒中のルテニウムの組成とメタノール酸化活性の関係を図８に示す。図８から分かるように、パラジウムとルテニウムの組成には最適な組成が存在し、白金触媒より高い活性を示す範囲はパラジウム：ルテニウム＝８５：１５～３０：７０であり、好ましくは、パラジウム：ルテニウム＝７０：３０～４５：５５の範囲であり、更に好ましくは、パラジウム：ルテニウム＝６５：３５～５０：５０の範囲であることが分かった。 As can be seen from the results in Table 2, the catalysts of Examples 1 to 5 showed higher catalytic activity than the platinum catalyst of Comparative Example 3. FIG. 8 shows the relationship between the composition of ruthenium in the palladium / ruthenium oxide catalyst and the methanol oxidation activity. As can be seen from FIG. 8, there is an optimum composition of palladium and ruthenium, and the range showing higher activity than the platinum catalyst is palladium: ruthenium = 85: 15 to 30:70, preferably palladium: ruthenium. = 70: 30-45: 55, more preferably palladium: ruthenium = 65: 35-50: 50.
　次に、実施例１の触媒と実施例６の触媒のＲｕ３ｄスペクトルをＸＰＳで分析した結果を図９に示す。実施例１の触媒に比べて、実施例６のピークは低エネルギー側にシフトしており、ルテニウムの金属成分が多かった。図９のスペクトルを、ピーク分離により、各成分を定量解析した結果を表３に示す。実施例１の触媒においては、金属ルテニウム成分が全く見られなかったのに対して、実施例６の触媒では、３２原子％の金属ルテニウムが存在していた。 Next, FIG. 9 shows the results of analyzing the Ru3d spectra of the catalyst of Example 1 and the catalyst of Example 6 by XPS. Compared with the catalyst of Example 1, the peak of Example 6 was shifted to the low energy side, and there were many metal components of ruthenium. Table 3 shows the result of quantitative analysis of each component of the spectrum of FIG. 9 by peak separation. In the catalyst of Example 1, no metal ruthenium component was found, whereas in the catalyst of Example 6, 32 atomic% of metal ruthenium was present.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　次に、実施例１と実施例６の触媒のアルカリ電解質中でのメタノール酸化活性を評価した。なお、メタノール酸化活性の評価方法は前述と同様とした。実施例１と実施例６のメタノール酸化活性評価結果を表４に示す。 Next, the methanol oxidation activity of the catalysts of Examples 1 and 6 in the alkaline electrolyte was evaluated. The evaluation method for methanol oxidation activity was the same as described above. Table 4 shows the evaluation results of methanol oxidation activity of Example 1 and Example 6.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表４の結果から分かるとおり、ルテニウムが全て酸化物状態である実施例１の方が高いメタノール酸化活性を示した。このことから、酸化ルテニウムに含まれる金属状態のルテニウムは極力少ないことが好ましく、酸化ルテニウムが多い方が高いメタノール酸化活性を得られることが分かる。 As can be seen from the results in Table 4, Example 1 in which all ruthenium was in an oxide state showed higher methanol oxidation activity. From this, it is understood that the ruthenium oxide contained in the ruthenium oxide is preferably as little as possible, and the higher the ruthenium oxide, the higher the methanol oxidation activity.
（評価２）
　実施例１の触媒と比較例３の触媒の酸電解質中でのメタノール酸化活性を評価した。評価は、０.５ｍｏｌ／Ｌの硫酸と１.０ｍｏｌ／Ｌメタノールを含む電解質溶液を用いること以外は評価１と同様とした。得られた結果における０.６Ｖ時の金属重量（mg）当たりの電流値を表５に示す。 (Evaluation 2)
The methanol oxidation activity of the catalyst of Example 1 and the catalyst of Comparative Example 3 in the acid electrolyte was evaluated. Evaluation was the same as Evaluation 1 except that an electrolyte solution containing 0.5 mol / L sulfuric acid and 1.0 mol / L methanol was used. Table 5 shows current values per metal weight (mg) at 0.6 V in the obtained results.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表５の結果から、酸電解質中では実施例１の触媒のメタノール酸化活性は、比較例３の白金触媒よりも低かった。したがって、実施例１の触媒はアルカリ電解質、すなわち水酸化物イオンを伝導するアニオン交換型固体高分子電解質膜と組み合わせることで白金触媒以上の高い活性を示すことが分かる。 From the results in Table 5, the methanol oxidation activity of the catalyst of Example 1 was lower than that of the platinum catalyst of Comparative Example 3 in the acid electrolyte. Therefore, it can be seen that the catalyst of Example 1 exhibits a higher activity than the platinum catalyst when combined with an alkaline electrolyte, that is, an anion exchange type solid polymer electrolyte membrane that conducts hydroxide ions.
　以上より、アニオン交換型固体高分子電解質膜を用いた燃料電池用膜／電極接合体のアノードに本実施例に係る触媒を含ませることで、高い出力密度が実現できる。 As described above, high power density can be realized by including the catalyst according to the present embodiment in the anode of the fuel cell membrane / electrode assembly using the anion exchange type solid polymer electrolyte membrane.
　図１０は、本実施例に係るメタノール水溶液を燃料とした燃料電池の展開斜視図である。 FIG. 10 is a developed perspective view of a fuel cell using a methanol aqueous solution as a fuel according to the present embodiment.
　拡散層６が両面に配置された燃料電池用膜／電極接合体７を、ガス流路が形成された１対のセパレータ１０１で挟み、一つの燃料電池セル（単位セル）が構成される。この単位セルが複数個積層され、外部回路と接続される集電板８、絶縁板９および端板１０を用いて締め付けることで燃料電池が構成される。燃料電池用膜／電極接合体７、セパレータ１０１、集電板８、絶縁板９、及び、端板１０には、燃料、酸化剤ガスや冷却水の出入り口となるマニホールド４が形成されている。燃料と酸化剤ガスはマニホールド４から供給され、セパレータ１０１のガス流路を通って、燃料がアノード、酸化剤ガスがカソードにそれぞれ供給されることで発電が行われる。未反応燃料を含む排液はセパレータ１０１のガス流路を通って出口側のマニホールド４から外部に排出される。 A fuel cell membrane / electrode assembly 7 in which the diffusion layer 6 is disposed on both surfaces is sandwiched between a pair of separators 101 in which gas flow paths are formed to constitute one fuel cell (unit cell). A plurality of the unit cells are stacked, and a fuel cell is configured by tightening using a current collector plate 8, an insulating plate 9, and an end plate 10 connected to an external circuit. The fuel cell membrane / electrode assembly 7, the separator 101, the current collector plate 8, the insulating plate 9, and the end plate 10 are formed with a manifold 4 serving as an inlet / outlet port of fuel, oxidant gas, and cooling water. Fuel and oxidant gas are supplied from the manifold 4, and electricity is generated by supplying fuel to the anode and oxidant gas to the cathode through the gas flow path of the separator 101. The waste liquid containing unreacted fuel passes through the gas flow path of the separator 101 and is discharged from the outlet-side manifold 4 to the outside.
　ここで、セパレータ１０１は周囲が平坦で、中央部を押出しプレス成型して流路を形成したものである。流路部はセパレータの表裏に反応ガス（燃料ガスと酸化剤ガスの総称）や冷却水を流通させるための凹凸状の溝である。セパレータ１０１の表裏面は平坦部においてそれぞれ２枚のガスケットが密着され、ガスケットによってセパレータ１０１の表裏面の反応ガスが混ざらないようにシールされている。図１０において、セパレータ１０１は２種類で構成され、両面に反応ガスを流通させるガスケット付きセパレータ１０１Ａと、片面が反応ガス用、反対面が冷却水用のセパレータ１０１Ｂで構成されている。なお、冷却水用の流路が形成されたセパレータには、マニホールド４から供給された冷却水が流れ、単位セルの温度が所定の温度範囲内になるように冷却するための冷却部となる。 Here, the separator 101 has a flat periphery and is formed by extruding the center part and press-molding to form a flow path. The flow path part is an uneven groove for allowing reaction gas (generic name for fuel gas and oxidant gas) and cooling water to flow through the front and back of the separator. Two gaskets are in close contact with each other on the front and back surfaces of the separator 101, and the reaction gas on the front and back surfaces of the separator 101 is sealed by the gasket so as not to mix. In FIG. 10, the separator 101 is composed of two types, a separator 101A with a gasket for allowing reaction gas to flow on both sides, and a separator 101B for reaction gas on one side and a cooling water separator 101B on the other side. Note that the cooling water supplied from the manifold 4 flows through the separator in which the cooling water flow path is formed, and serves as a cooling unit for cooling so that the temperature of the unit cell is within a predetermined temperature range.
　このようにして構成された燃料電池において、アニオン交換型固体高分子電解質膜を用いた燃料電池用膜／電極接合体のアノードに本実施例に係る触媒を含ませることで、高い出力密度を実現することができる。 In the fuel cell configured as described above, a high power density is realized by including the catalyst according to this example in the anode of the fuel cell membrane / electrode assembly using the anion exchange type solid polymer electrolyte membrane. can do.
　ここで、本実施例に係る燃料電池では、有機物を含む液体を用いることができるが、有機物としてメタノール、エタノールを用いることが好ましい。メタノールは、エネルギー密度が高く、且つ、二酸化炭素まで容易に酸化でき、反応副生成物を生じにくい。一方、エタノールはメタノール同様にエネルギー密度が高く、且つ、メタノールに比べて安全性が高いため、好ましい。しかし、二酸化炭素まで酸化することが困難であるため、酢酸やアセトアルデヒドなどの副生成物を生じやすい。燃料に含ませる有機物として、メタノールを用いるか、エタノールを用いるかは、燃料電池の適用先で望まれる特性から選択することができる。 Here, in the fuel cell according to the present embodiment, a liquid containing an organic substance can be used, but it is preferable to use methanol or ethanol as the organic substance. Methanol has a high energy density and can be easily oxidized up to carbon dioxide, and hardly produces a reaction byproduct. On the other hand, ethanol is preferable because it has a high energy density like methanol and is safer than methanol. However, since it is difficult to oxidize to carbon dioxide, byproducts such as acetic acid and acetaldehyde are likely to be generated. Whether the organic substance contained in the fuel is methanol or ethanol can be selected from characteristics desired by the application destination of the fuel cell.
　そして、作製した燃料電池を、燃料電池発電システムの一例として、携帯用情報端末に実装した例を図１１に示す。この携帯用情報端末は、２つの部分を、燃料カートリッジ１１６のホルダーをかねたヒンジ１１７で連結された折たたみ式の構造をとっている。１つの部分は、タッチパネル式入力装置が一体化された表示装置１１１、アンテナ１１２を内蔵した部分を有する。１つの部分は、燃料電池１１３、プロセッサ、揮発及び不揮発メモリ、電力制御部、燃料電池及び二次電池ハイブリッド制御、燃料モニタなどの電子機器及び電子回路などを実装したメインボード１１４、リチウムイオン二次電池１１５を搭載した部分を有する。このようにして得られる携帯用情報端末は、燃料電池の出力密度が高いため、小型で軽量な構成とすることができる。 And the example which mounted the produced fuel cell in the portable information terminal as an example of a fuel cell power generation system is shown in FIG. This portable information terminal has a foldable structure in which two parts are connected by a hinge 117 that also serves as a holder for the fuel cartridge 116. One portion includes a display device 111 in which a touch panel type input device is integrated and a portion in which an antenna 112 is incorporated. One part includes a fuel cell 113, a processor, a volatile and nonvolatile memory, a power control unit, a fuel cell and secondary battery hybrid control, a main board 114 on which an electronic device and an electronic circuit such as a fuel monitor are mounted, a lithium ion secondary It has a portion on which a battery 115 is mounted. The portable information terminal thus obtained has a high output density of the fuel cell, and thus can be configured to be small and lightweight.
１１、２１　アニオン交換型固体高分子電解質膜
１２、２２　アノード
１３　カソード
１４　アノード拡散層
１５　カソード拡散層
２３、３１　カーボンブラック
２４　樹脂
３２　パラジウム
３３　酸化ルテニウム
１０１　セパレータ
１０２　ガスケット
１０３　アノード集電体
１０４　カソード集電体
１０５　外部回路
１０６　メタノール水溶液
１０７　廃液
１０８　空気
１０９　排ガス
１１１　表示装置
１１２　アンテナ
１１３　燃料電池
１１４　メインボード
１１５　リチウムイオン二次電池
１１６　燃料カートリッジ
１１７　ヒンジ 11, 21 Anion exchange type solid polymer electrolyte membranes 12, 22 Anode 13 Cathode 14 Anode diffusion layer 15 Cathode diffusion layer 23, 31 Carbon black 24 Resin 32 Palladium 33 Ruthenium oxide 101 Separator 102 Gasket 103 Anode current collector 104 Cathode current collector Body 105 External circuit 106 Methanol aqueous solution 107 Waste liquid 108 Air 109 Exhaust gas 111 Display device 112 Antenna 113 Fuel cell 114 Main board 115 Lithium ion secondary battery 116 Fuel cartridge 117 Hinge

Claims (8)

  1. 　燃料を酸化するアノードと、酸素を還元するカソードと、前記アノードと前記カソードとの間に配置されるアニオン交換型固体高分子電解質膜と、を備える燃料電池用膜／電極接合体において、前記アノードにパラジウムと酸化ルテニウムが含まれていることを特徴とする燃料電池用膜／電極接合体。 A membrane / electrode assembly for a fuel cell, comprising: an anode that oxidizes fuel; a cathode that reduces oxygen; and an anion exchange type solid polymer electrolyte membrane disposed between the anode and the cathode. A membrane / electrode assembly for a fuel cell, characterized in that it contains palladium and ruthenium oxide.
  2. 　請求項１に記載の燃料電池用膜／電極接合体において、前記パラジウムと、前記酸化ルテニウムに含まれるルテニウムの組成が、原子比で８５：１５から３０：７０の範囲であることを特徴とする燃料電池用膜／電極接合体。 2. The fuel cell membrane / electrode assembly according to claim 1, wherein the composition of the palladium and ruthenium contained in the ruthenium oxide is in the range of 85:15 to 30:70 in atomic ratio. Membrane / electrode assembly for fuel cells.
  3. 　請求項２に記載の燃料電池用膜／電極接合体において、前記アノードに含まれる前記パラジウムと前記酸化ルテニウムが、カーボン担体に担持されていることを特徴とする燃料電池用膜／電極接合体。 3. The fuel cell membrane / electrode assembly according to claim 2, wherein the palladium and the ruthenium oxide contained in the anode are supported on a carbon support.
  4. 　アニオン交換型固体高分子電解質膜の両面に一対のアノード及びカソードが配置された膜／電極接合体と、前記膜／電極接合体を挟持する一対のセパレータとを備える燃料電池において、
    　前記アノードにパラジウムと酸化ルテニウムが含まれていることを特徴とする燃料電池。     In a fuel cell comprising: a membrane / electrode assembly in which a pair of anodes and cathodes are disposed on both surfaces of an anion exchange type solid polymer electrolyte membrane; and a pair of separators sandwiching the membrane / electrode assembly.
    A fuel cell, wherein the anode contains palladium and ruthenium oxide.
  5. 　請求項４に記載の燃料電池において、前記パラジウムと、前記酸化ルテニウムに含まれるルテニウムの組成が、原子比で８５：１５から３０：７０の範囲であることを特徴とする燃料電池。 5. The fuel cell according to claim 4, wherein the composition of palladium and ruthenium contained in the ruthenium oxide is in the range of 85:15 to 30:70 in atomic ratio.
  6. 　請求項４に記載の燃料電池において、前記燃料が液体有機物を含むことを特徴とする燃料電池。 5. The fuel cell according to claim 4, wherein the fuel contains a liquid organic substance.
  7. 　請求項４に記載の燃料電池において、前記燃料がメタノールを含む水溶液であることを特徴とする燃料電池。 5. The fuel cell according to claim 4, wherein the fuel is an aqueous solution containing methanol.
  8. 　請求項４に記載の燃料電池を搭載した燃料電池発電システム。 A fuel cell power generation system equipped with the fuel cell according to claim 4.
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* Cited by examiner, † Cited by third party
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CN111628187A (en) * 2020-05-05 2020-09-04 江苏大学 Carbon-supported ruthenium oxide catalyst and preparation method thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002527875A (en) * 1998-10-08 2002-08-27 イネオス・クロール・リミテッド Bipolar plates for fuel cells
JP2003077521A (en) * 2001-08-31 2003-03-14 Foundation For Advancement Of Science & Technology Fuel cell
WO2007011004A1 (en) * 2005-07-15 2007-01-25 Kyoto University Co tolerant multicomponent electrode catalyst for solid polymer fuel cell
JP2007157703A (en) * 2005-11-10 2007-06-21 Ricoh Co Ltd Anode catalyst and its manufacturing method
JP2007522921A (en) * 2004-01-06 2007-08-16 アイシー・イノベーションズ・リミテッド Nanoporous / Mesoporous palladium catalyst

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002527875A (en) * 1998-10-08 2002-08-27 イネオス・クロール・リミテッド Bipolar plates for fuel cells
JP2003077521A (en) * 2001-08-31 2003-03-14 Foundation For Advancement Of Science & Technology Fuel cell
JP2007522921A (en) * 2004-01-06 2007-08-16 アイシー・イノベーションズ・リミテッド Nanoporous / Mesoporous palladium catalyst
WO2007011004A1 (en) * 2005-07-15 2007-01-25 Kyoto University Co tolerant multicomponent electrode catalyst for solid polymer fuel cell
JP2007157703A (en) * 2005-11-10 2007-06-21 Ricoh Co Ltd Anode catalyst and its manufacturing method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111628187A (en) * 2020-05-05 2020-09-04 江苏大学 Carbon-supported ruthenium oxide catalyst and preparation method thereof

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