JP2015128058A - Anode catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode catalyst composition capable of more highly improving power generation performance by activating an oxidation reaction of fuel in a fuel-side electrode of a fuel battery.SOLUTION: In a fuel battery 1 supplied with liquid fuel, an anode catalyst contained in a fuel-side electrode 2 contains nickel-based metal and electron conductive particles, and the anode catalyst contains nickel-based metal of 80 pts. mass and more to a total amount of 100 pts. mass of the nickel-based metal and the electron conductive particles.

Description

  The present invention relates to an anode catalyst for a fuel cell.

  To date, various types of fuel cells such as alkaline type (AFC), solid polymer type (PEFC), phosphoric acid type (PAFC), molten carbonate type (MCFC), and solid electrolyte type (SOFC) are known. It has been. Especially, since a polymer electrolyte fuel cell can be operated at a relatively low temperature, use in various applications such as an automobile application is being studied.

  For example, a polymer electrolyte fuel cell includes a fuel-side electrode (anode) to which fuel is supplied and an oxygen-side electrode (cathode) to which oxygen is supplied. These electrodes are formed from a solid polymer membrane. Are arranged opposite to each other with an electrolyte layer interposed therebetween.

  In such a fuel cell, a catalyst is usually contained in each electrode in order to increase the efficiency of power generation. Specifically, as a polymer electrolyte fuel cell, for example, as a catalyst, cobalt and nickel are used. A fuel cell including a fuel-side electrode (anode), an oxygen-side electrode (cathode), and an electrolyte layer that can move an anion component has been proposed (see, for example, Patent Document 1).

  As described in Patent Document 1, in the fuel cell, when cobalt and nickel are contained in the fuel-side electrode, for example, power generation performance can be improved as compared with a case where only cobalt is contained. it can.

  Further, in such a polymer electrolyte fuel cell, in order to further improve the power generation performance, it has been proposed that the fuel side electrode contains zinc and nickel instead of cobalt and nickel (for example, (Refer nonpatent literature 1.).

JP 2010-225471 A

The Electrochemical Society, 2010, ECS Transactions, 33 (1), 1673-1680.

  However, in recent years, further improvement in the power generation performance of the fuel cell is desired, and therefore a catalyst capable of realizing a more excellent fuel cell is required.

  An object of the present invention is to provide an anode catalyst capable of activating a fuel electrochemical reaction at a fuel-side electrode of a fuel cell and further improving power generation performance.

  In order to achieve the above object, an anode catalyst of the present invention is an anode catalyst of a fuel cell to which a liquid fuel is supplied, which contains a nickel-based metal and electron conductive particles, 80 mass parts or more of nickel-type metals are contained with respect to 100 mass parts of total amounts of electron conductive particles.

  In addition, the anode catalyst of the present invention is preferably obtained by physically mixing the nickel-based metal and the electron conductive particles.

  The anode catalyst of the present invention contains a nickel-based metal and electron conductive particles, and the nickel-based metal is contained in an amount of 80 parts by mass or more with respect to 100 parts by mass of the total amount of the nickel-based metal and the electron conductive particles. Yes.

  Therefore, by activating the electrochemical reaction of the fuel at the fuel side electrode of the fuel cell, the output of the fuel cell can be increased and the power generation performance can be improved.

It is a schematic block diagram which shows one Embodiment of the fuel cell using the fuel side electrode containing the anode catalyst of this invention. 3 is a measurement result of hydrazine oxidation activity of fuel side electrodes including anode catalysts of Examples 1 to 3 and Comparative Example 1. FIG. 5 is a measurement result of hydrazine oxidation activity of a fuel side electrode including an anode catalyst of Example 1 and Example 4. FIG. 6 is a measurement result of hydrazine oxidation activity of a fuel side electrode including an anode catalyst of Example 5 and Comparative Example 2. FIG. 7 is a measurement result of hydrazine oxidation activity of a fuel side electrode including an anode catalyst of Comparative Example 3 and Comparative Example 4. 10 is a measurement result of hydrazine oxidation activity of a fuel side electrode including an anode catalyst of Comparative Example 5 and Comparative Example 6. FIG. 6 is a measurement result of cell power generation characteristics of a fuel cell using a fuel side electrode including an anode catalyst of Example 1 and Comparative Example 1. FIG.

  The anode catalyst of the present invention contains a nickel (Ni) metal and electron conductive particles.

  Examples of the nickel-based metal include nickel alone (nickel single metal), an alloy (nickel alloy) of nickel and other (other than nickel) metal, and a nickel-containing composite oxide.

  The nickel simple metal may be obtained by a known method, or a commercially available product may be obtained.

  Other metals (other than nickel) include, for example, platinum group elements (Ru, Rh, Pd, Os, Ir, Pt), periodic table elements 8 to 10 (IUPAC Periodic Table of) such as iron group elements (Fe, Co). according to the Elements (version date 19 February 2010). The same shall apply hereinafter.) Group elements and periodic table group 11 elements such as Cu, Ag and Au, for example, periodic table group 12 elements such as Zn, Cd and Hg For example, Mn, Zr, Pb, Sn, W, Bi, Nb, Mo, La, etc., and combinations thereof are also included.

  The other metal (other than nickel) is preferably Zn (zinc).

Specific examples of the nickel alloy include NiZn, Ni ₃ Mn, Ni ₃ Co, Ni ₃ Ag, Ni ₃ Zr, Ni ₃ Pd, Ni ₃ Fe, Ni ₃ Cu, Ni ₃ Pb, Ni ₃ Sn, and Ni _{3. W, Ni 3 Bi, Ni 3} Nb, Ni 3 Mo, NiRu, and the like Nila.

  In the nickel alloy, nickel is, for example, 65 to 95 mol%, preferably 75 to 95 mol%, more preferably 80 to 90 mol%, based on the total mol of nickel and other (other than nickel) metals. The other metal is, for example, 5 to 35 mol%, preferably 5 to 25 mol%, more preferably 10 to 20 mol%.

  When the content ratio of each metal in the nickel alloy is the above ratio, excellent power generation performance can be obtained.

  The nickel alloy may be synthesized by a known method, or a commercially available product may be obtained.

  The nickel-containing composite oxide is preferably a perovskite composite oxide represented by the following general formula (1).

ANiO ₃ (1)
(In the formula, A represents at least one element selected from rare earth elements and alkaline earth metals.)
In the general formula (1), A represents at least one element selected from rare earth elements and alkaline earth metals, and preferably represents at least one element selected from rare earth elements.

  In the general formula (1), examples of the rare earth element represented by A include Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm ( Promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu ( Lutetium).

  Examples of the alkaline earth metal represented by A include Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium), and Ra (radium).

  These rare earth elements and alkaline earth metals can be used alone or in combination of two or more. As the rare earth element and the alkaline earth metal, La (lanthanum) is preferable.

  Such a nickel-containing composite oxide is not particularly limited. For example, in accordance with the description of paragraph numbers [0039] to [0059] of JP-A-2004-243305, a composite oxide can be prepared. It can be produced by an appropriate method, for example, a production method such as a coprecipitation method, a citric acid complex method, or an alkoxide method.

As the nickel-containing composite oxide, LaNiO ₃ is preferably used. These nickel-containing composite oxides can be used alone or in combination of two or more.

  These nickel-based metals can be used alone or in combination of two or more.

The nickel-based metal is preferably Ni, NiZn, LaNiO ₃ , more preferably Ni, NiZn, and still more preferably NiZn.

  The average particle diameter of the nickel-based metal is, for example, 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and, for example, 100 μm or less, preferably 50 μm or less, more preferably Is 10 μm or less.

  When the average particle diameter of the nickel-based metal is in the above range, excellent power generation performance can be obtained.

Examples of the electron conductive particles include carbon such as carbon black, ketjen black, and acetylene black, metal oxides such as TiO, VO, and WO ₃ , such as ReO ₃ , SrTiO ₃ , BaTiO ₃ , LaTiO ₃ , Examples thereof include perovskite oxides such as CaVO ₃ , SrVO ₃ , CaCrO ₃ , SrCrO ₃ , CaFeO ₃ , SrFeO ₃ , and LaCoO ₃ .

  These electron conductive particles can be used alone or in combination of two or more.

  The electron conductive particles are preferably carbon, more preferably ketjen black.

  The average particle diameter of the electron conductive particles is, for example, 0.001 μm or more, preferably 0.005 μm or more, more preferably 0.01 μm or more, and for example, 1 μm or less, preferably 0.5 μm or less. More preferably, it is 0.1 μm or less.

  When the average particle diameter of the electron conductive particles is within the above range, excellent power generation performance can be obtained.

  In order to produce the anode catalyst of the present invention, a nickel-based metal and electron conductive particles are mixed.

  The mixing method is not particularly limited as long as it can be physically mixed, and examples thereof include known mixing methods such as dry mixing and wet mixing. Preferably, dry mixing is used.

  As the form of the obtained anode catalyst, the nickel-based metal and the electron conductive particles are physically mixed, and the nickel-based metal is not supported on the electron conductive particles.

  Therefore, the nickel-based metal can be contained in a larger proportion than when the nickel-based metal is supported on the electron conductive particles.

  Thereby, an anode catalyst containing a nickel-based metal and electron conductive particles is obtained.

  The anode catalyst is preferably composed only of nickel-based metal and electron conductive particles.

  In the anode catalyst, the content ratio of the nickel-based metal and the electron conductive particles is, for example, 80 parts by mass or more, preferably 83, of the nickel-based metal with respect to 100 parts by mass of the total amount of the nickel-based metal and the electron conductive particles. Part by mass, more preferably 85 parts by mass or more, more preferably 90 parts by mass or more, for example, 99 parts by mass or less, preferably 98 parts by mass or less, more preferably 96 parts by mass or less, Further, the electron conductive particles are, for example, 1 part by mass or more, preferably 2 parts by mass or more, more preferably 4 parts by mass or more, for example, 20 parts by mass or less, preferably 17 parts by mass or less, more Preferably, it is 15 mass parts or less, More preferably, it is 10 mass parts or less.

  When the content ratio of the nickel-based metal and the electron conductive particles is the above ratio, excellent power generation performance can be obtained.

  The ratio between the average particle diameter of the nickel-based metal and the average particle diameter of the electron conductive particles is such that the average particle diameter of the electron conductive particles is, for example, 0.01% or more with respect to the average particle diameter of the nickel-based metal. , Preferably 0.05% or more, more preferably 0.1% or more, and for example, 25% or less, preferably 10% or less, more preferably 5% or less, and even more preferably 2%. It is as follows.

  When the ratio between the average particle diameter of the nickel-based metal and the average particle diameter of the electron conductive particles is the above ratio, excellent power generation performance can be obtained.

  Details of the fuel cell in which the fuel side electrode including the anode catalyst of the present invention is used will be described below.

  FIG. 1 is a schematic configuration diagram showing an embodiment of a fuel cell using a fuel-side electrode including an anode catalyst of the present invention. In FIG. 1, the fuel cell 1 includes a fuel cell S, and the fuel cell S includes a fuel side electrode 2, an oxygen side electrode 3, and an electrolyte layer 4, and the fuel side electrode 2 and the oxygen side electrode 3. However, they are opposed to each other with the electrolyte layer 4 sandwiched therebetween.

  The fuel-side electrode 2 includes the above-described anode catalyst, and is in opposed contact with one surface of the electrolyte layer 4.

  Although it does not restrict | limit especially in forming such a fuel side electrode 2, For example, a membrane-electrode assembly is formed. The membrane-electrode assembly can be formed by a known method. For example, first, the anode catalyst and the electrolyte solution described above are mixed, and if necessary, an appropriate solvent such as alcohol or ether, or a resin such as ionomer is added to adjust the viscosity. An electrode ink is prepared. Next, the anode electrode ink is coated on the surface of the electrolyte layer 4 (anion exchange membrane) to fix the anode catalyst to the surface of the electrolyte layer 4.

The usage-amount of an anode catalyst is 0.01-5 mg / cm < ² >, for example.

In the fuel-side electrode 2, as will be described later, a supplied compound containing at least hydrogen and nitrogen (hereinafter referred to as “fuel compound”) and hydroxide ions (OH ⁻ ) that have passed through the electrolyte layer 4 are supplied. To produce electrons (e ⁻ ), nitrogen (N ₂ ), and water (H ₂ O).

  The oxygen side electrode 3 is in opposed contact with the other surface of the electrolyte layer 4. Although this oxygen side electrode 3 is not specifically limited, For example, it is formed as a porous electrode with which a cathode catalyst is carry | supported.

The cathode catalyst is not particularly limited as long as it has a catalytic action of generating hydroxide ions (OH ⁻ ) from oxygen (O ₂ ) and water (H ₂ O), as will be described later. For example, Group 8-10 of the periodic table (IUPAC Periodic Table of the Elements (version date 19 February) such as platinum group elements (Ru, Rh, Pd, Os, Ir, Pt) and iron group elements (Fe, Co, Ni). The same applies hereinafter.) Elements, Group 11 elements of the periodic table such as Cu, Ag, Au, etc., and combinations thereof are also included. Among these, Fe is preferable. The supported amount of the cathode catalyst is, for example, 0.1 to 10 mg / cm ² , preferably 0.1 to 5 mg / cm ² . The cathode catalyst is preferably supported on the carbon.

  Moreover, a phenanthroline Fe complex can also be used as a cathode catalyst.

  The phenanthroline Fe complex is a transition metal complex in which a phenanthroline-based ligand is coordinated to iron, and the phenanthroline-based ligand is phenanthroline or a derivative thereof, preferably 1,10-phenanthroline or a derivative thereof. It is done.

  In the phenanthroline Fe complex, the phenanthroline-based ligand is coordinated with, for example, three molecules of iron as a bidentate ligand.

  Specific examples of the phenanthroline Fe complex include tris (phenanthroline) iron (II) complex.

  Moreover, a phenanthroline Mn complex, a phenanthroline Ni complex, etc. can also be used together with a phenanthroline Fe complex as needed.

  Forming the oxygen side electrode 3 from such a cathode catalyst is not particularly limited. For example, a membrane-electrode assembly is formed in the same manner as the fuel side electrode 2 described above.

  That is, for example, first, the above-described cathode catalyst and the electrolyte solution are mixed, and if necessary, an appropriate solvent such as alcohol or ether, or a resin such as ionomer is added to adjust the viscosity. A cathode electrode ink is prepared. Next, the cathode electrode ink is coated on the surface of the electrolyte layer 4 (anion exchange membrane) to fix the cathode catalyst to the surface of the electrolyte layer 4.

In the oxygen-side electrode 3, as will be described later, the supplied oxygen (O ₂ ), water (H ₂ O), and the electrons (e ⁻ ) that have passed through the external circuit 13 are reacted to form a hydroxide. Ion (OH ⁻ ) is generated.

The electrolyte layer 4 is formed from an anion exchange membrane. The anion exchange membrane is not particularly limited as long as it is a medium that can move hydroxide ions (OH ⁻ ) generated at the oxygen side electrode 3 from the oxygen side electrode 3 to the fuel side electrode 2. Examples thereof include a solid polymer membrane (anion exchange resin) having an anion exchange group such as a quaternary ammonium group or a pyridinium group.

  The fuel cell S further includes a fuel supply member 5 and an oxygen supply member 6. The fuel supply member 5 is made of a gas-impermeable conductive member, and one surface thereof is in opposed contact with the fuel-side electrode 2. The fuel supply member 5 is formed with a fuel-side flow path 7 for bringing fuel into contact with the entire fuel-side electrode 2 as a distorted groove recessed from one surface. The fuel-side flow path 7 has a supply port 8 and a discharge port 9 that pass through the fuel supply member 5 formed continuously at the upstream end and the downstream end, respectively.

  Similarly to the fuel supply member 5, the oxygen supply member 6 is made of a gas-impermeable conductive member, and one surface thereof is opposed to the oxygen side electrode 3. The oxygen supply member 6 is also formed with an oxygen-side flow channel 10 for contacting oxygen (air) with the entire oxygen-side electrode 3 as a distorted groove recessed from one surface. The oxygen-side flow path 10 also has a supply port 11 and a discharge port 12 that pass through the oxygen supply member 6 continuously formed at the upstream end portion and the downstream end portion thereof.

  The fuel cell 1 is actually formed as a stack structure in which a plurality of the fuel cells S described above are stacked. Therefore, the fuel supply member 5 and the oxygen supply member 6 are actually configured as separators in which the fuel side flow path 7 and the oxygen side flow path 10 are formed on both surfaces.

  Although not shown, the fuel cell 1 is provided with a current collector plate formed of a conductive material, and an electromotive force generated in the fuel cell 1 is taken out from a terminal provided on the current collector plate. It is configured to be able to.

  Further, on a test (model) basis, the fuel supply member 5 and the oxygen supply member 6 of the fuel cell S are connected by an external circuit 13, and a voltmeter 14 is interposed in the external circuit 13 to generate the fuel cell S. The voltage can also be measured.

  And in this invention, the fuel containing the said fuel compound, Preferably the liquid fuel containing the said fuel compound is supplied directly, without passing through reforming etc.

  In this fuel compound, hydrogen is preferably bonded directly to nitrogen. The fuel compound preferably has a nitrogen-nitrogen bond, and preferably does not have a carbon-carbon bond. Further, it is preferable that the number of carbons is as small as possible (zero if possible).

  Further, such a fuel compound may contain an oxygen atom, a sulfur atom, etc. within a range not impairing its performance, and more specifically, a carbonyl group, a hydroxyl group, a hydrate, a sulfonic acid group or a sulfuric acid group. It may be contained as a salt or the like.

From this point of view, specific examples of the fuel compound in the present invention include hydrazine (NH ₂ NH ₂ ), hydrazine hydrate (NH ₂ NH ₂ .H ₂ O), and hydrazine carbonate ((NH ₂ NH). _{2) 2} CO _2), hydrazine sulfate _{(NH 2 NH 2 · H 2} SO 4), monomethyl hydrazine _(CH 3 NHNH _2), dimethylhydrazine _{((CH 3) 2 NNH 2} , CH 3 NHNHCH 3), a carboxylic hydrazide ( Hydrazines such as (NHNH ₂ ) ₂ CO), eg urea (NH ₂ CONH ₂ ), eg ammonia (NH ₃ ) eg imidazole, 1,3,5-triazine, 3-amino-1,2, heterocyclic compounds such as 4-triazoles, e.g., hydroxylamine _(NH 2 OH), hydroxylamine sulfate (NH OH _· H 2 SO _4), and the like hydroxylamines such. Such fuel compounds can be used alone or in combination of two or more. Preferably, hydrazines are used.

Among the above fuel compounds, compounds not containing carbon, that is, hydrazine (NH ₂ NH ₂ ), hydrazine hydrate (NH ₂ NH ₂ .H ₂ O), hydrazine sulfate (NH ₂ NH ₂ .H ₂ SO ₄ ) , Ammonia (NH ₃ ), hydroxylamine (NH ₂ OH), and hydroxylamine sulfate (NH ₂ OH · H ₂ SO ₄ ) are durable because there is no poisoning of the catalyst by CO as in the case of hydrazine reaction described later. Can be improved and substantially zero emission can be realized.

  As the fuel, the fuel compound exemplified above may be used as it is, but the fuel compound exemplified above is used as a solution such as water and / or alcohol (for example, lower alcohol such as methanol, ethanol, propanol, isopropanol). Can be used. In this case, the concentration of the fuel compound in the solution varies depending on the type of fuel compound, but is, for example, 1 to 90% by weight, preferably 1 to 30% by weight.

Then, if the above-described fuel is supplied to the fuel-side channel 7 of the fuel supply member 5 while supplying oxygen (air) to the oxygen-side channel 10 of the oxygen supply member 6, As described, the electrons (e ⁻ ) generated in the fuel side electrode 2 and moving via the external circuit 13 react with water (H ₂ O) and oxygen (O ₂ ) to generate hydroxide ions. (OH ⁻ ) is generated. The generated hydroxide ions (OH ⁻ ) move from the oxygen side electrode 3 to the fuel side electrode 2 through the electrolyte layer 4 made of an anion exchange membrane. In the fuel-side electrode 2, the hydroxide ions (OH ⁻ ) that have passed through the electrolyte layer 4 react with the fuel to generate electrons (e ⁻ ). The generated electrons (e ⁻ ) are moved from the fuel supply member 5 to the oxygen supply member 6 via the external circuit 13 and supplied to the oxygen side electrode 3. An electromotive force is generated by such an electrochemical reaction in the fuel side electrode 2 and the oxygen side electrode 3, and power generation is performed.

In such an electrochemical reaction, in the fuel side electrode 2, a one-stage reaction in which hydroxide ions (OH ⁻ ) are directly reacted with the fuel, and the fuel is hydrogen (H ₂ ) and nitrogen (N ₂ ). There are two types of reactions: a two-stage reaction in which a hydroxide ion (OH ⁻ ) is reacted with hydrogen (H ₂ ) generated by the decomposition.

For example, when hydrazine (NH ₂ NH ₂ ) is used as the fuel, the one-stage reaction can be expressed by the following reaction formulas (2) to (4) as the fuel side electrode 2, the oxygen side electrode 3 and the whole. it can.
(2) NH ₂ NH ₂ + 4OH ⁻ → 4H ₂ O + N ₂ + 4e ⁻ (fuel side electrode)
(3) O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (oxygen side electrode)
(4) NH ₂ NH ₂ + O ₂ → 2H ₂ O + N ₂ (whole)
The two-stage reaction can be expressed by the following reaction formulas (5) to (8) as the fuel side electrode 2, the oxygen side electrode 3, and the whole.
(5) NH ₂ NH ₂ → 2H ₂ + N ₂ (decomposition reaction; fuel side electrode)
(6) H ₂ + 2OH ⁻ → 2H ₂ O + 2e ⁻ (fuel side electrode)
(7) 1 / 2O ₂ + H ₂ O + 2e ⁻ → 2OH ⁻ (oxygen side electrode)
(8) H ₂ + 1 / 2O ₂ → H ₂ O (whole)
As shown in the above reaction formula (5), in the two-stage reaction, hydrazine (NH ₂ NH ₂ ) is once decomposed into hydrogen (H ₂ ) and nitrogen (N ₂ ). Causes energy loss. For this reason, when the ratio of the two-stage reaction to the one-stage reaction is increased, the fuel utilization efficiency is decreased and the calorific value is increased.

However, in the fuel cell 1, as described above, the fuel side electrode 2 includes an anode catalyst containing a nickel-based metal and electron conductive particles as a metal catalyst. The metal content is 80 parts by mass or more based on 100 parts by mass of the total amount of nickel-based metal and electron conductive particles. This anode catalyst suppresses the decomposition reaction (decomposition reaction represented by the above formula (5)) of the fuel (hydrazine in the above example) and directly reacts the fuel with hydroxide ions (OH ⁻ ) (the above formula ( The reaction shown in 2) can be promoted. Therefore, by activating the electrochemical reaction of the fuel at the fuel side electrode of the fuel cell, the fuel cell can be increased in output and the power generation performance can be improved.

  Moreover, since the anode catalyst of the present invention contains nickel-based metal and electron conductive particles, the amount of metal used is reduced as compared with the case where only nickel-based metal is used as the metal catalyst. Therefore, the cost can be improved.

  Furthermore, since the output of the fuel cell is increased, the number of fuel cell stacks can be reduced, and the fuel cell can be made compact (downsized).

  The operating conditions of the fuel cell 1 are not particularly limited. For example, the pressure on the fuel side electrode 2 side is 200 kPa or less, preferably 100 kPa or less, and the pressure on the oxygen side electrode 3 side is 200 kPa or less. Preferably, it is 100 kPa or less, and the temperature of the fuel cell S is set to 0 to 120 ° C., preferably 20 to 80 ° C.

  As mentioned above, although embodiment of this invention was described, embodiment of this invention is not limited to this, A design can be suitably changed in the range which does not change the summary of this invention.

  Applications of the fuel cell of the present invention include, for example, power sources for driving motors in automobiles, ships, airplanes, etc., and power sources in communication terminals such as mobile phones.

Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited by the following Example. In the following description, “part” and “%” are based on mass unless otherwise specified. In addition, the numerical value of the Example shown below can be substituted to the corresponding numerical value (namely, upper limit value or lower limit value) described in embodiment.
<Synthesis of anode catalyst composition>
Example 1
Nickel-based metal nickel-zinc alloy (NiZn) (AQ672078, Ni: 87% by mass, Zn: 13% by mass, average particle size: 3 μm, manufactured by Cabot) 10 mg, and ketjen black (Ek conductive particles) 1 mg of ketjen black ECP-600JD, average particle size: 0.05 μm, manufactured by Lion, respectively, was weighed using an electronic balance, put into a mortar, pulverized with a mortar for about 5 minutes, and mixed. Anode catalyst A was synthesized. The content ratio of the nickel-based metal in the anode catalyst A was 91 parts by mass with respect to 100 parts by mass of the total amount of the nickel-based metal and the electron conductive particles.
(Example 2)
Nickel-based metal nickel-zinc alloy (NiZn) (AQ672078, Ni: 87% by mass, Zn: 13% by mass, average particle size: 3 μm, manufactured by Cabot) 10 mg, and ketjen black (Ek conductive particles) 0.5 mg of Ketjen Black ECP-600JD (average particle size: 0.05 μm, manufactured by Lion) was weighed using an electronic balance, placed in a mortar, ground with a mortar for about 5 minutes, and mixed. Thus, anode catalyst B was synthesized. The content ratio of the nickel-based metal in the anode catalyst B was 95 parts by mass with respect to 100 parts by mass of the total amount of the nickel-based metal and the electron conductive particles.
(Example 3)
Nickel-based metal catalyst, nickel-zinc alloy (NiZn) (AQ672078, Ni: 87% by mass, Zn: 13% by mass, average particle size: 3 μm, manufactured by Cabot) 10 mg, and ketjen black, which is an electron conductive particle 2 mg (Ketjen Black ECP-600JD, average particle size: 0.05 μm, manufactured by Lion) are weighed using an electronic balance, put in a mortar, pulverized with a mortar for about 5 minutes, and mixed. Anode catalyst C was synthesized. The content ratio of the nickel-based metal in the anode catalyst C was 83 parts by mass with respect to 100 parts by mass of the total amount of the nickel-based metal and the electron conductive particles.
Example 4
Nickel-based metal nickel (Ni) (210H, average particle size: 0.2 μm, manufactured by Inco) 10 mg and electron conductive particles Ketjen black (Ketjen black ECP-600JD, average particle size: 0) 0.05 mg, manufactured by Lion) was weighed using an electronic balance, put into a mortar, pulverized with a mortar stick for about 5 minutes, and mixed to synthesize anode catalyst D. The content ratio of the nickel-based metal in the anode catalyst D was 91 parts by mass with respect to 100 parts by mass of the total amount of the nickel-based metal and the electron conductive particles.
(Example 5)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O, manufactured by Kishida Chemical Co., Ltd.) 3.64 g (lanthanum terms: 1.17 g) and nickel nitrate hexahydrate _{(Ni (NO 3) 2 ·} 6H ₂ O, manufactured by Kishida chemical Co., Ltd.) 2.42 g (nickel terms: 0.49 g) to prepare a metallic aqueous solution dissolved in deionized water 50 ml. Next, the prepared aqueous metal solution was supplied at a rate of 5 ml / min into 400 ml of tetramethylammonium hydroxide (C ₄ H ₁₃ NO, product code: T0676, manufactured by Tokyo Chemical Industry Co., Ltd.) stirred at 450 rpm. The mixture was stirred for more than an hour to obtain a precipitate (coprecipitate). Thereafter, the obtained precipitate was washed with water, filtered with suction, and dried in an oven at 110 ° C. for 12 hours. Next, the obtained dried product was fired at 800 ° C. for 5 hours in an air atmosphere to obtain LaNiO ₃ (average particle size: 3 μm) which is a nickel-based metal (nickel-containing composite oxide).

10 mg of LaNiO ₃ (average particle size: 3 μm) obtained above and 1 mg of Ketjen Black (Ketjen Black ECP-600JD, average particle size: 0.05 μm, manufactured by Lion), which is an electron conductive particle, Each was weighed using an electronic balance, placed in a mortar, pulverized with a mortar stick for about 5 minutes, and mixed to synthesize anode catalyst E. The content ratio of the nickel-based metal in the anode catalyst E was 91 parts by mass with respect to 100 parts by mass of the total amount of the nickel-based metal and the electron conductive particles.
(Comparative Example 1)
A nickel-zinc alloy (NiZn) (AQ672078, Ni: 87% by mass, Zn: 13% by mass, average particle size: 3 μm, manufactured by Cabot Co.), 10 mg, which is a nickel-based metal, is weighed using an electronic balance and placed in a mortar. Anode catalyst F was synthesized by pulverizing with a mortar for about 5 minutes. The anode catalyst F does not contain electron conductive particles.
(Comparative Example 2)
10 mg of LaNiO ₃ (average particle size: 3 μm) obtained in Example 5 was weighed using an electronic balance, placed in a mortar, and pulverized with a mortar bar for about 5 minutes to synthesize anode catalyst G. The anode catalyst G does not contain electron conductive particles.
(Comparative Example 3)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O, manufactured by Kishida Chemical Co., Ltd.) 3.63 g (lanthanum terms: 1.17 g) and cobalt nitrate hexahydrate _{(Co (NO 3) 2 ·} 6H ₂ O, manufactured by Kishida chemical Co., Ltd.) 2.42 g (cobalt conversion: 0.49 g) to prepare a metallic aqueous solution dissolved in deionized water 50 ml. Next, the prepared aqueous metal solution was supplied at a rate of 5 ml / min into 400 ml of tetramethylammonium hydroxide (C ₄ H ₁₃ NO, product code: T0676, manufactured by Tokyo Chemical Industry Co., Ltd.) stirred at 450 rpm. The mixture was stirred for more than an hour to obtain a precipitate (coprecipitate). Thereafter, the obtained precipitate was washed with water, filtered with suction, and dried in an oven at 110 ° C. for 12 hours. Next, the obtained dried product was fired at 800 ° C. for 5 hours in an air atmosphere to obtain LaCoO ₃ (average particle size: 3 μm) as a composite oxide.

10 mg of LaCoO ₃ (average particle size: 3 μm) obtained above and 1 mg of Ketjen Black (Ketjen Black ECP-600JD, average particle size: 0.05 μm, manufactured by Lion), which is an electron conductive particle, Each was weighed using an electronic balance, placed in a mortar, pulverized with a mortar stick for about 5 minutes, and mixed to synthesize anode catalyst H. The content ratio of the composite oxide in the anode catalyst H was 91 parts by mass with respect to 100 parts by mass of the total amount of the composite oxide and the electron conductive particles.
(Comparative Example 4)
10 mg of LaCoO ₃ (average particle size: 3 μm) obtained in Comparative Example 3 was weighed using an electronic balance, placed in a mortar, and ground with a mortar bar for about 5 minutes to synthesize anode catalyst I. The anode catalyst I does not contain electron conductive particles.
(Comparative Example 5)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O, manufactured by Kishida Chemical Co., Ltd.) 3.69 g (lanthanum terms: 1.18 g) and manganese nitrate hexahydrate _{(Mn (NO 3) 2 ·} 6H ₂ O, manufactured by Kishida chemical Co.) 2.42 g (manganese terms: 0.46 g) to prepare a metallic aqueous solution dissolved in deionized water 50 ml. Next, the prepared aqueous metal solution was supplied at a rate of 5 ml / min into 400 ml of tetramethylammonium hydroxide (C ₄ H ₁₃ NO, product code: T0676, manufactured by Tokyo Chemical Industry Co., Ltd.) stirred at 450 rpm. The mixture was stirred for more than an hour to obtain a precipitate (coprecipitate). Thereafter, the obtained precipitate was washed with water, filtered with suction, and dried in an oven at 110 ° C. for 12 hours. Next, the obtained dried product was fired at 800 ° C. for 5 hours in an air atmosphere to obtain LaMnO ₃ (average particle size: 3 μm) as a composite oxide.

10 mg of LaMnO ₃ (average particle size: 3 μm) obtained above and 1 mg of Ketjen Black (Ketjen Black ECP-600JD, average particle size: 0.05 μm, manufactured by Lion), which is an electron conductive particle, Each was weighed using an electronic balance, placed in a mortar, pulverized with a mortar stick for about 5 minutes, and mixed to synthesize anode catalyst J. The content ratio of the composite oxide in the anode catalyst J was 91 parts by mass with respect to 100 parts by mass of the total amount of the composite oxide and the electron conductive particles.
(Comparative Example 6)
10 mg of LaMnO ₃ (average particle size: 3 μm) obtained in Comparative Example 5 was weighed using an electronic balance, placed in a mortar, and ground with a mortar bar for about 5 minutes to synthesize anode catalyst K. The anode catalyst K does not contain electron conductive particles.

(Evaluation)
Using the anode catalyst obtained in each example and each comparative example, a test piece of a fuel side electrode including the anode catalyst of each example and each comparative example was prepared, and its activity was measured. In addition, a fuel cell was manufactured using the fuel-side electrode containing the anode catalyst obtained in Example 1 and Comparative Example 1, and the cell power generation characteristics were measured.
<Production of test piece>
Pure water 3.2 mL, 2-propanol 0.6 mL, tetrahydrofuran 0.184 mL and anion exchange ionomer (A3, ionomer concentration: 2 mass%, solvent (tetrahydrofuran: 1-propanol = 1: 1 (mass ratio)), Tokuyama 0.004 g of the anode catalyst of each example and each comparative example was added to 16 μL of the mixed solution, and the mixture was subjected to dispersion treatment for 5 minutes using an ultrasonic disperser.

Thereafter, 20 μL of the obtained dispersion was taken with a micropipette, dropped onto a working electrode for evaluating electrochemical activity (glassy carbon electrode), and dried at 60 ° C. in a standby atmosphere for about 1 hour. As a result, a fuel-side electrode test piece including the anode catalyst of each example and each comparative example was obtained.
<Activity measurement>
A mixed solution of 1M KOH and 0.1M hydrazine as an electrolytic solution was prepared, put into a 50 ml glass cell (manufactured by PINE), and degassed with argon gas for about 15 minutes. Subsequently, the reference electrode, the auxiliary electrode, and each test piece were set in the glass cell. Subsequently, potentiostat (ALS660a, manufactured by CH Instruments) was connected to the three electrodes, and the hydrazine oxidation activity was measured by an electrochemical measurement method (cyclic voltammetry) using a rotating disk electrode. The scanning range of the potential was −1.2 V (vs. Hg / HgO) to −0.2 V (vs. Hg / HgO), and the electrode rotation speed was 1600 rpm.

The measurement conditions are shown below.
Initial potential: -1.2 V (vs. Hg / HgO)
Reference electrode; Hg / HgO
Auxiliary electrode; Pt plate scanning speed; 0.02 V / s
Segment: 4 times The results are shown in FIGS.
<Manufacture of fuel cells>
A cell unit of an anion exchange membrane-electrode assembly was produced, and its cell power generation characteristics were measured.

  In the production of the anion exchange membrane-electrode assembly, first, 0.15 g of the anode catalyst composition of Example 1 or Comparative Example 1, an anion exchange ionomer (mixed solution of A3 and AS4, ionomer concentration: 2% by mass, solvent) (Tetrahydrofuran: 1-propanol = 1: 1 (mass ratio)), manufactured by Tokuyama) 0.831 g and a mixed solution of 1-propanol and tetrahydrofuran (1-propanol: tetrahydrofuran = 1: 1 (mass ratio)) Each anode electrode ink was prepared by mixing 5 g.

  Next, 0.1 g of tris (phenanthroline) iron (II) complex (TSP06, phenanthroline Fe complex catalyst, manufactured by Daihatsu Kogyo Co., Ltd.), anion exchange ionomer ((mixed solution of A3 and AS4, ionomer concentration: 2% by mass, solvent) (Tetrahydrofuran: 1-propanol = 1: 1 (mass ratio)), manufactured by Tokuyama) 1.0032 g and a mixed solution of 1-propanol and tetrahydrofuran (tetrahydrofuran: 1-propanol = 1: 1 (mass ratio)) 0 g was mixed to prepare a cathode electrode ink.

Furthermore, the anode electrode ink was placed on one side surface of the anion exchange type electrolyte membrane (A201CE Tokuyama Co., Ltd.) so that the amount of the anode catalyst was 2.6 mg / cm ^2, and the amount of the cathode catalyst was 1.0 mg on the other side surface. the cathode ink so that / cm ^2, the area of each the dried surface was coated to a 2 cm ^2, the anion exchange membrane - was prepared electrode assembly.

Thereafter, the solvent was evaporated in the air, and each of the obtained anion exchange membrane-electrode assemblies was immersed in 1M KOH for 12 hours or more.
<Measurement of cell power generation characteristics>
Each anion exchange membrane-electrode assembly is set in a fuel cell evaluation cell (Lab cell, manufactured by Daihatsu Kogyo Co., Ltd.), and a mixed solution of 1M KOH and 20% by volume hydrated hydrazine is supplied to the anode side. Air was supplied at a flow rate of 2 cc / min and 0.5 L / min, respectively, and the current density was controlled with an electronic load device (890e, manufactured by Scriber Associates), and the voltage of the cell at that time was measured.

The measurement conditions are shown below.
Cell temperature: 80 ° C
Back pressure; anode: 10 kPa, cathode: 60 kPa
The result is shown in FIG.

2 Fuel side electrode 3 Oxygen side electrode 4 Electrolyte layer S Fuel cell

Claims (2)

An anode catalyst for a fuel cell supplied with liquid fuel,
Containing nickel-based metal and electron conductive particles,
An anode catalyst comprising 80 parts by mass or more of a nickel-based metal with respect to 100 parts by mass of the total amount of the nickel-based metal and the electron conductive particles.   The anode catalyst according to claim 1, wherein the anode catalyst is obtained by physically mixing the nickel-based metal and the electron conductive particles.

Images