WO2010041650A1 - Catalyst, method for producing the same, and use thereof - Google Patents

Abstract

Provided is a catalyst that is not corroded in an acidic electrolyte or under high electric potential, has excellent durability, and has high oxygen-reducing capability.  The catalyst is formed from a metal oxycarbonitride comprising 0.2 mass% or more of each, and a total of 25 mass% or more, of two metals (metal A and metal Z hereafter) selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum, and tungsten, wherein when the metal oxycarbonitride is measured by powder X-ray diffraction (Cu－kα rays), four or more diffraction ray peaks are observed at a diffraction angle 2θ between 33° and 43°.

Description

Catalyst, method for producing the same and use thereof

The present invention relates to a catalyst, a production method thereof, and an application thereof.

Catalysts have the function of accelerating the rate of reaction that should proceed in terms of chemical equilibrium by lowering the activation energy of the reaction, and are used in a wide variety of chemical reaction processes such as synthesis and decomposition. Among these, homogeneous catalysts can be efficiently dissolved in a liquid phase or the like by being dissolved or dispersed in a solvent. Heterogeneous catalysts can be synthesized on a support by efficiently synthesizing or decomposing the target substance, and the catalyst can be easily separated and recovered from the product. Especially useful in large chemical synthesis factories. Among heterogeneous catalysts, a catalyst that is used for an electrochemical reaction by being fixed on the electrode surface and allows the intended reaction to proceed with a smaller overvoltage is called an electrode catalyst. Electrocatalysts are particularly needed for fuel cells for the purpose of reducing overvoltage and generating more electrical energy.

Fuel cells are classified into various types according to the type of electrolyte and the type of electrode, and representative types include alkali type, phosphoric acid type, molten carbonate type, solid electrolyte type, and solid polymer type. Among them, a polymer electrolyte fuel cell that can operate at a low temperature (about −40 ° C.) to about 120 ° C. attracts attention, and in recent years, development and practical application as a low-pollution power source for automobiles is progressing. As a use of the polymer electrolyte fuel cell, a vehicle driving source and a stationary power source are being studied. However, in order to be applied to these uses, durability over a long period of time is required.

In this polymer solid fuel cell, a polymer solid electrolyte is sandwiched between an anode and a cathode, fuel is supplied to the anode, oxygen or air is supplied to the cathode, and oxygen is reduced at the cathode to extract electricity. is there. Hydrogen or methanol is mainly used as the fuel.

Conventionally, in order to increase the reaction rate of the fuel cell and increase the energy conversion efficiency of the fuel cell, the fuel cell cathode (air electrode) surface or anode (fuel electrode) surface has a layer containing a catalyst (hereinafter referred to as “for fuel cell”). Also referred to as “catalyst layer”).

As this catalyst, a noble metal is generally used, and among the noble metals, platinum which is stable at a high potential and has high activity has been mainly used. However, since platinum is expensive and has limited resources, the development of an alternative catalyst has been sought.

In addition, the noble metal used on the cathode surface may be dissolved in an acidic atmosphere, and there is a problem that it is not suitable for applications that require long-term durability. Therefore, there has been a strong demand for the development of a catalyst that does not corrode in an acidic atmosphere, has excellent durability, and has a high oxygen reducing ability.

In recent years, materials containing non-metals such as carbon, nitrogen, and boron have been attracting attention as catalysts instead of platinum. These non-metal-containing materials are cheaper and have abundant resources than precious metals such as platinum.

Non-Patent Document 1 reports that a ZrOxN compound based on zirconium exhibits oxygen reducing ability.

Patent Document 1 discloses an oxygen reduction electrode material containing a nitride of one or more elements selected from the group of elements of groups 4, 5 and 14 of the long periodic table as a platinum substitute material.

However, these non-metal containing materials have a problem that a sufficient oxygen reducing ability is not practically obtained as a catalyst.

Patent Document 2 discloses a carbonitride oxide obtained by mixing carbide, oxide, and nitride and heating at 500 to 1500 ° C. in a vacuum, inert or non-oxidizing atmosphere.

However, the carbonitrous oxide disclosed in Patent Document 2 is a thin film magnetic head ceramic substrate material, and the use of this carbonitrous oxide as a catalyst has not been studied.

Patent Document 3 discusses the possibility that an oxide having a perovskite structure containing two or more kinds of metals can serve as a platinum substitute catalyst. As shown in the examples, the effect is supplemented by platinum. It does not go beyond its role as a carrier and does not have sufficient activity.

Although platinum is useful not only as a catalyst for the fuel cell, but also as an exhaust gas treatment catalyst or an organic synthesis catalyst, platinum is expensive and has limited resources. There has been a demand for the development of a catalyst that can be used in various applications.

JP 2007-31781 A Japanese Patent Laid-Open No. 2003-342058 Japanese Patent Laid-Open No. 2008-4286

S.Doi, A.Ishihara, S.Mitsushima, N.kamiya, and K.Ota, `` Journal of The Electrochemical Society '', 2007, 154 (3) B362-B369

An object of the present invention is to solve such problems in the prior art, and an object of the present invention is to provide a catalyst that does not corrode in an acidic electrolyte or at a high potential, has excellent durability, and has a high oxygen reduction ability. There is.

As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors have found that a catalyst composed of oxycarbonitride containing two specific types of metals in a specific ratio is present in an acidic electrolyte or at a high potential. The inventors have found that it does not corrode, has excellent durability, and has a high oxygen reducing ability, and has completed the present invention.

The present invention relates to the following (1) to (17), for example.

(1)
0.2% by mass or more of one type of metal A selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten,
Containing 0.2% by mass or more of one kind of metal Z selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten (provided that metal Z is a metal different from metal A). And
And the total of the metal A and the metal Z is 25% by mass or more, and consists of a metal oxycarbonitride,
When the metal carbonitride is measured by powder X-ray diffraction (Cu-Kα ray), four or more diffraction line peaks are observed at a diffraction angle of 2θ = 33 ° to 43 °. And a catalyst.

(2)
The metal oxycarbonitride is a mixture containing a oxycarbonitride containing metal A and a oxycarbonitride containing metal Z. The catalyst according to (1), containing 2% by mass or more and containing 0.2% by mass or more of metal oxynitride containing metal Z in terms of metal.

(3)
The catalyst according to (1) or (2), wherein a molar ratio between the metal A and the metal Z (metal A / metal Z) is 1 or more and 15 or less.

(4)
Any of (1) to (3), wherein the combination of the metal A and the metal Z is the following (a) and (b), the following (a) and (c), or the following (b) and (c) A catalyst according to claim 1;
(A) One type of metal selected from the group consisting of titanium and zirconium (b) One type of metal selected from the group consisting of vanadium, niobium and tantalum (c) One type of metal selected from the group consisting of molybdenum and tungsten.

(5)
The composition formula of the metal oxycarbonitride is A _a Z _b C _x N _y O _z (where A represents the metal A, Z represents the metal Z, and a, b, x, y, and z represent the number of atoms. 0.01 ≦ a <1, 0 <b ≦ 0.99, 0.01 ≦ x ≦ 2, 0.01 ≦ y ≦ 2, 0.01 ≦ z ≦ 3, a + b = 1, and x + y + z ≦ 5.) The catalyst according to any one of (1) to (4),

(6)
(1) A catalyst layer for a fuel cell comprising the catalyst according to any one of (5).

(7)
The catalyst layer for a fuel cell as described in (6), further comprising electron conductive particles.

(8)
An electrode having a fuel cell catalyst layer and a porous support layer, wherein the fuel cell catalyst layer is the fuel cell catalyst layer according to (6) or (7).

(9)
A membrane electrode assembly having a cathode, an anode, and an electrolyte membrane disposed between the cathode and the anode, wherein the cathode and / or the anode is an electrode according to (8) Membrane electrode assembly.

(10)
A fuel cell comprising the membrane electrode assembly according to (9).

(11)
A polymer electrolyte fuel cell comprising the membrane electrode assembly according to (9).

(12)
An article having at least one function selected from the group consisting of a power generation function, a light emission function, a heat generation function, a sound generation function, an exercise function, a display function, and a charge function, and the fuel cell according to (10) or (11) An article characterized by comprising:

(13)
The article is a building material, a lighting fixture, a design window glass, a machine, a vehicle, a glass product, a household appliance, an agricultural material, an electronic device, a mobile phone, a beauty appliance, a portable information terminal, a tool, tableware, a bath product, a toilet product, Furniture, clothing, fabric products, textiles, leather products, paper products, resin products, sports equipment, futons, containers, glasses, signs, piping, wiring, metal fittings, sanitary materials, automotive supplies, stationery, patches, hats, bags, shoes, Umbrellas, blinds, balloons, lighting, light emitting diodes (LEDs), traffic lights, street lights, toys, road signs, ornaments, tents, traffic lights, bulletin boards, outdoor equipment, teaching materials, artificial flowers, objects, power supplies for heart pacemakers, Peltier elements The article according to (12), which is at least one selected from the group consisting of a power supply for a heater provided and a power supply for a cooler provided with a Peltier element.

(14)
One type of metal A oxide selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten, and one type selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten Metal carbonitride by heating a mixture of an oxide of metal Z (wherein metal Z is a different type of metal from metal A) and carbon in a nitrogen atmosphere in the range of 600 to 2000 ° C. Obtaining a product (ia);
The method according to any one of (1) to (5), further comprising a step (ii) of obtaining the metal carbonitride by heating the metal carbonitride in an oxygen-containing inert gas. A method for producing a catalyst.

(15)
One or more compounds selected from the group consisting of the metal A oxide, the metal A nitride, and the metal A carbide, the metal Z oxide, the metal Z nitride, and the metal Z A mixture with one or more compounds selected from the group consisting of carbides (provided that the mixture contains at least carbides) in an inert gas (however, if the mixture does not contain nitrides, a nitrogen atmosphere) And (ib) to obtain a metal carbonitride by heating in the range of 600 to 2000 ° C.
The method according to any one of (1) to (5), further comprising a step (ii) of obtaining the metal carbonitride by heating the metal carbonitride in an oxygen-containing inert gas. A method for producing a catalyst.

(16)
The method for producing a catalyst according to (14) or (15), wherein the heating temperature in the step (ii) is in the range of 400 to 1400 ° C.

(17)
The method for producing a catalyst according to any one of (14) to (16), wherein the oxygen gas concentration in the step (ii) is in the range of 0.1 to 10% by volume.

The catalyst of the present invention does not corrode in an acidic electrolyte or at a high potential, is stable, has a high oxygen reducing ability, and is less expensive than platinum. Therefore, the fuel cell including the catalyst is relatively inexpensive and has excellent performance.

1 is a powder X-ray diffraction spectrum of the catalyst (1) of Example 1. FIG. FIG. 2 is an enlarged view of the powder X-ray diffraction spectrum of the catalyst (1) of Example 1. FIG. 3 is a powder X-ray diffraction spectrum of the catalyst (2) of Example 2. 4 is an enlarged view of the powder X-ray diffraction spectrum of the catalyst (2) of Example 2. FIG. FIG. 5 is a powder X-ray diffraction spectrum of the catalyst (3) of Example 3. FIG. 6 is an enlarged view of a powder X-ray diffraction spectrum of the catalyst (3) of Example 3. FIG. 7 is a powder X-ray diffraction spectrum of the catalyst (4) of Example 4. FIG. 8 is an enlarged view of the powder X-ray diffraction spectrum of the catalyst (4) of Example 4. FIG. 9 is a powder X-ray diffraction spectrum of the catalyst (5) of Example 5. FIG. 10 is an enlarged view of a powder X-ray diffraction spectrum of the catalyst (5) of Example 5. FIG. 11 is a powder X-ray diffraction spectrum of the catalyst (6) of Example 6. FIG. 12 is an enlarged view of the powder X-ray diffraction spectrum of the catalyst (6) of Example 6. FIG. 13 is a powder X-ray diffraction spectrum of the catalyst (10) of Comparative Example 1. 14 is an enlarged view of the powder X-ray diffraction spectrum of the catalyst (10) of Comparative Example 1. FIG. FIG. 15 is a powder X-ray diffraction spectrum of the catalyst (11) of Comparative Example 2. FIG. 16 is an enlarged view of the powder X-ray diffraction spectrum of the catalyst (11) of Comparative Example 2. FIG. 17 is a graph showing an evaluation of the oxygen reducing ability of the catalyst (1) of Example 1. FIG. 18 is a graph showing an evaluation of the oxygen reducing ability of the catalyst (10) of Comparative Example 1.

<Catalyst>
The catalyst of the present invention is characterized by comprising a specific metal carbonitride. The metal oxycarbonitride is a metal A selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten, and a group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten. 1 type of metal Z chosen more (however, metal Z shall be a different kind of metal from metal A) is contained in a specific ratio.

One of the characteristics generally required for the catalyst is durability, but the catalyst of the present invention improves the acid resistance and high potential durability by containing the metal A and the metal Z. Yes. Although it is not clear about this mechanism of action, the inclusion of two or more metal components in the catalyst renders the other metal passivated even under potential conditions where a local site in the catalyst elutes. Therefore, it is presumed that there is a function to prevent further elution.

Furthermore, in addition to the metal A and the metal Z, the catalyst of the present invention includes at least one metal M selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten (where the metal M is It may be a different type of metal from metal A and metal Z). A catalyst made of a metal oxynitride containing two or more of these metals exceeds the catalytic ability of a catalyst made of a metal oxynitride containing a single metal, and has an oxygen reduction catalytic activity according to a platinum compound. Show.

The combination of the metal A and the metal Z is preferably the following (a) and (b), the following (a) and (c), or the following (b) and (c).

(A) A kind of metal selected from the group consisting of titanium and zirconium.

(B) A kind of metal selected from the group consisting of vanadium, niobium and tantalum.

(C) A kind of metal selected from the group consisting of molybdenum and tungsten.

Specific examples of such combinations of metal A and metal Z include zirconium and tantalum, titanium and niobium, zirconium and niobium, vanadium and molybdenum. When the metal A and the metal Z are in a combination as described above, the acid resistance tends to increase while exhibiting catalytic activity.

Further, the metal carbonitride oxide contains the metal A and the metal Z in an amount of 0.2% by mass or more, respectively, and a total of 25% by mass or more. The total content of the metal A and the metal Z is usually 25% by mass or more, more preferably 40% or more, more preferably in consideration of the stability in an acidic solution at a high potential. It is 55% mass or more. When the total content of the metal A and the metal Z is 75% by mass or more, particularly strong oxygen reduction activity can be exhibited. Although the upper limit of the total content of the metal A and the metal Z is not particularly limited, it is, for example, 99.5% by mass. In addition, when each metal component is contained in an amount of 0.2% by mass or more, the characteristics as the second component, that is, the properties of preventing further elution can be exhibited by the passivation of the metal of the second component. . It is more preferable that each metal component is contained in an amount of 0.8% by mass or more, and further more preferable that it contains 2.0% by mass or more. Although the upper limit of content of the said metal A is not specifically limited, For example, it is 99.5 mass%. Although the upper limit of content of the said metal Z is not specifically limited, For example, it is 99.5 mass%.

The total content (mass percentage) of the metal A and the metal Z in the catalyst composed of the metal carbonitrous oxide is the total content of carbon, nitrogen and oxygen contained in the catalyst from the mass of the entire catalyst ( It is obtained by subtracting (mass percentage). The contents (mass percentage) of carbon, nitrogen and oxygen contained in the catalyst can be determined by elemental analysis.

In the present invention, the metal A represents a metal species that is equal to or more than the metal Z in the catalyst. The molar ratio of the metal A and the metal Z (metal A / metal Z) in the catalyst is preferably 1 or more and 15 or less, more preferably 1.5 or more and 15 or less, and more preferably 2 or more and 10 or less. More preferably, it is as follows.

The metal oxycarbonitride used in the present invention is one in which at least the metal A, the metal Z, carbon, nitrogen and oxygen are detected when elemental analysis is performed. In addition, when a diffraction pattern of a metal oxycarbonitride containing one kind of metal is confirmed by a powder X-ray diffraction method (Cu-Kα ray), the diffraction angle is usually between 2θ = 33 ° and 43 °. Two or more diffraction line peaks are observed. Since the metal oxycarbonitride used in the present invention contains two or more kinds of metals, the diffraction angle 2θ = 33 ° to 43 ° when measured by a powder X-ray diffraction method (Cu—Kα ray). In the meantime, four or more diffraction line peaks are observed.

A diffraction line peak means a peak obtained with a specific diffraction angle and diffraction intensity when a sample (crystalline) is irradiated with X-rays at various angles. In the present invention, a signal that can be detected when the ratio (S / N) of the signal (S) to the noise (N) is 2 or more is regarded as one diffraction line peak. Here, the noise (N) is the width of the baseline.

As an X-ray diffractometer, for example, a powder X-ray analyzer: Rigaku RAD-RX can be used. The measurement conditions are X-ray output (Cu-Kα): 50 kV, 180 mA, scanning axis. : Θ / 2θ, measurement range (2θ): 10 ° to 89.98 °, measurement mode: FT, read width: 0.02 °, sampling time: 0.70 seconds, DS, SS, RS: 0.5 ° 0.5 °, 0.15 mm, goniometer radius: 185 mm.

The metal oxycarbonitride used in the present invention is a metal carbonitride, in which oxygen is partially incorporated into the crystal lattice, or a metal oxide contained in the metal carbonitride is generated, Whether it is a mixture of metal carbonitride and metal oxide, or a mixture of materials such as metal carbonitride, metal oxide, intercrystalline oxygen interpenetrating compound, and carbonitride of the same metal Of the compounds having the same metal oxide structure, it is difficult to identify whether it is a mixture with a compound in which part of oxygen of the oxide is partially substituted with carbon and nitrogen. Therefore, the metal oxycarbonitride used in the present invention may be a mixture of two or more substances. Further, the oxycarbonitride containing two or more kinds of metals may be a mixture of a total of four or more substances.

The metal oxynitride used in the present invention may be a single solid solution, but more preferably a mixture in which a nitrous oxide containing metal A and a nitrous oxide containing metal Z are separated into two phases. It is preferable that it exists as. Moreover, the catalyst which consists of the said mixture contains 0.2 mass% or more of the carbonitrous oxide containing the metal A in metal conversion, and contains 0.2 mass% or more of the carbonitrous oxide containing the metal Z in metal conversion. It is preferable that the nitrous oxide containing metal A contains 0.8% by mass or more in terms of metal, and more preferable that the nitrous oxide containing metal Z contains 0.8% by mass or more in terms of metal, More preferably, the carbonitrous oxide containing metal A contains 2.0% by mass or more in terms of metal, and the carbonitrous oxide containing metal Z contains 2.0% by mass or more in terms of metal. Although the upper limit of the metal conversion amount of the oxycarbonitride containing the metal A is not specifically limited, For example, it is 99.5 mass%. Moreover, although the upper limit of the metal conversion amount of the oxycarbonitride containing the metal A is not specifically limited, For example, it is 99.5 mass%.

As described above, since the catalyst of the present invention may be a mixture, it is difficult to individually determine the ratio of carbon, nitrogen, and oxygen contained in each metal carbonitride. However, when the metal A is “A” and the metal Z is “Z”, the composition formula of the metal oxycarbonitride is A _a Z _b C _x N _y O _z (where a, b, x, y and z represent the ratio of the number of atoms, 0.01 ≦ a <1, 0 <b ≦ 0.99, 0.01 ≦ x ≦ 2, 0.01 ≦ y ≦ 2, 0.01 ≦ z ≦ 3. A + b = 1 and x + y + z ≦ 5).

In the above composition formula, 0.05 ≦ a ≦ 0.99, 0.01 ≦ b ≦ 0.95, 0.05 ≦ x ≦ 2, 0.05 ≦ y ≦ 2, 0.05 ≦ z ≦ 3, and More preferably, 0.15 ≦ x + y + z ≦ 5. It is preferable that the ratio of the number of atoms is in the above range because the oxygen reduction potential tends to be high.

The catalyst of the present invention comprises a step (ia) of obtaining a metal carbonitride by heating a mixture of the metal A oxide, the metal Z oxide and carbon in a nitrogen atmosphere, and the metal carbonitride. It is preferable to manufacture via the process (ii) which obtains the said metal carbonitrous oxide by heating in oxygen-containing inert gas.

Further, the catalyst of the present invention includes at least one compound selected from the group consisting of the metal A oxide, the metal A nitride, and the metal A carbide, the metal Z oxide, and the metal Z. And a mixture of one or more compounds selected from the group consisting of the metal Z carbides (provided that the mixture contains at least carbides) in an inert gas (however, the nitrides in the mixture) In the nitrogen atmosphere.) (Ii) to obtain a metal carbonitride by heating in a nitrogen atmosphere, and the metal carbonitride by heating the metal carbonitride in an oxygen-containing inert gas. It is preferably produced via step (ii) of obtaining a nitrided oxide.

A catalyst obtained by such a production method is preferred because the oxygen reduction potential tends to be high. Details of these manufacturing methods will be described later.

The oxygen reduction initiation potential of the catalyst used in the present invention, which is measured according to the following measurement method (A), is preferably 0.5 V (vs. NHE) or more with respect to the standard hydrogen electrode.
[Measurement method (A):
The catalyst and carbon are placed in a solvent so that the amount of the catalyst dispersed in the carbon that is the electron conductive particles is 1% by mass, and the mixture is stirred with ultrasonic waves to obtain a suspension. As the carbon, carbon black (specific surface area: 100 to 300 m ² / g) (for example, XC-72 manufactured by Cabot Corporation) is used, and the catalyst and carbon are dispersed so that the mass ratio is 95: 5. As the solvent, isopropyl alcohol: water (mass ratio) = 1: 1 is used.

30 μl of the suspension is collected while applying ultrasonic waves, and is quickly dropped on a glassy carbon electrode (diameter: 5.2 mm) and dried at 120 ° C. for 1 hour. By drying, a catalyst layer for a fuel cell containing the catalyst is formed on the glassy carbon electrode.

Next, 10 μl of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10-fold with pure water is further dropped onto the fuel cell catalyst layer. This is dried at 120 ° C. for 1 hour.

In this way, the obtained electrode was used as a working electrode, and a temperature of 30 ° C. and a potential scanning rate of 5 mV / sec in a 0.5 mol / dm ³ sulfuric acid solution in an oxygen-saturated atmosphere using a Kinoshita glass ball filter. The linear sweep voltammetry was performed from 1.2V to 0.1V. A standard hydrogen electrode in a 0.5 mol / dm ³ sulfuric acid solution was used as a reference electrode, and a platinum mesh was used as a counter electrode. The same measurement was also performed in a nitrogen saturated atmosphere.

For the current-potential curve obtained by each measurement, the potential at which a difference of 1.0 μA / cm ² or more begins to appear between the reduction current in the oxygen-saturated atmosphere and the reduction current in the nitrogen-saturated atmosphere is defined as the oxygen reduction start potential. To do. ]
When the oxygen reduction starting potential is less than 0.7 V (vs. NHE), hydrogen peroxide may be generated when the catalyst is used as a catalyst for a cathode of a fuel cell. Further, the oxygen reduction starting potential is particularly preferably 0.8 V (vs. NHE) or more in order to suitably reduce oxygen. Further, the oxygen reduction starting potential is preferably as high as possible. Although there is no particular upper limit, it is difficult to exceed the chemical equilibrium theoretical value of 1.23 V (vs. NHE).

The fuel cell catalyst layer of the present invention formed using the above catalyst is preferably used at a potential of 0.4 V (vs. NHE) or more in the acidic electrolyte, and the upper limit of the potential depends on the stability of the electrode. It can be used up to approximately 1.23 V (vs. NHE), which is the potential at which oxygen is generated.

When this potential is less than 0.4 V (vs. NHE), there is no problem at all from the viewpoint of the stability of the compound, but oxygen cannot be suitably reduced, and the fuel of the membrane electrode assembly included in the fuel cell Usefulness as a battery catalyst layer is poor.

<Method for producing catalyst>
The method for producing the catalyst is not particularly limited. For example, two types of metals selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten (hereinafter also referred to as “metal A” and “metal Z”). ) Containing metal carbonitride is heated in an oxygen-containing inert gas, thereby producing a production method including a step of obtaining the metal carbonitride oxide containing the metal A and the metal Z.

As a method of obtaining the metal carbonitride used in the step, the metal carbonitride is heated by heating a mixture of the metal A oxide, the metal Z oxide, and carbon in a nitrogen atmosphere. Method (I) of manufacturing, one or more compounds selected from the group consisting of oxide of metal A, nitride of metal A and carbide of metal A, oxide of metal Z, and metal Z A mixture of at least one compound selected from the group consisting of a nitride and a carbide of the metal Z (provided that the mixture includes at least a carbide) in an inert gas (however, a nitride is contained in the mixture). When not included, it is in a nitrogen atmosphere.) (II) for producing a metal carbonitride by heating in a nitrogen atmosphere.

(Metallic carbonitride production method)
[Production Method (I)]
The production method (I) is a method for producing a metal carbonitride by heating a mixture of the metal A oxide, the metal Z oxide, and carbon in a nitrogen atmosphere.

The heating temperature for producing the metal carbonitride is preferably in the range of 600 ° C. to 2000 ° C., more preferably in the range of 800 to 1600 ° C. When the heating temperature is within the above range, it is preferable in terms of good crystallinity and uniformity of the obtained metal carbonitride. When the heating temperature is less than 600 ° C., the resulting metal carbonitride tends to have poor crystallinity and uniformity, and when it exceeds 2000 ° C., the obtained metal carbonitride tends to sinter. Tend.

Examples of raw material oxides of metal A and metal Z include titanium oxide, zirconium oxide, vanadium oxide, niobium oxide, tantalum oxide, molybdenum oxide, and tungsten oxide. One or more kinds of metal oxides can be used. In addition, in the above metal oxide, when the existence of oxides having a plurality of metal valences is known, any oxide may be used as a raw material. Further, when an oxide having a plurality of valences is used as a raw material among oxides of the same metal, higher catalytic activity may be obtained.

Examples of the raw material carbon include carbon, carbon black, graphite, graphite, activated carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, and fullerene. It is preferable that the particle size of the carbon powder is smaller because the specific surface area is increased and the reaction with the oxide is facilitated. For example, carbon black (specific surface area: 100 to 300 m ² / g, such as XC-72 manufactured by Cabot) is preferably used.

The total content of metal A and metal Z in the metal oxynitride finally obtained by controlling the addition amount of the oxide of metal A, the oxide of metal Z and the carbon of the raw material is the above It can be within a specific range, and the content of each metal component can be within the specific range.

Using any of the above raw materials, a metal carbonitriding oxidation obtained by heating a metal carbonitride obtained from the metal A oxide, the metal Z oxide and carbon in an oxygen-containing inert gas. A catalyst composed of a product has a high oxygen reduction initiation potential and is active.

Controlling the compounding amount (molar ratio) of the metal A oxide, the metal Z oxide and carbon, an appropriate metal carbonitride is obtained.

The compounding amount (molar ratio) is usually 0.01 to 1 mol of the oxide of the metal Z and 1 to 10 mol of carbon with respect to 1 mol of the metal A, preferably the metal A The amount of the metal Z oxide is 0.067 to 0.5 mol, and the carbon is 2 to 6 mol. When a metal carbonitride produced with a blending molar ratio satisfying the above range is used, there is a tendency that an oxygen reduction initiation potential is high and an active metal carbonitride oxide is obtained.

[Production Method (II)]
The production method (II) includes at least one compound selected from the group consisting of the metal A oxide, the metal A nitride, and the metal A carbide, the metal Z oxide, and the metal Z A mixture of at least one compound selected from the group consisting of a nitride and a carbide of the metal Z (provided that the mixture includes at least a carbide) in an inert gas (however, a nitride is contained in the mixture). When not included, it is in a nitrogen atmosphere.) This is a method for producing a metal carbonitride by heating.

The heating temperature for producing the metal carbonitride is preferably in the range of 600 ° C. to 2000 ° C., more preferably in the range of 800 to 1600 ° C. When the heating temperature is within the above range, it is preferable in terms of good crystallinity and uniformity of the obtained metal carbonitride. When the heating temperature is less than 600 ° C., the resulting metal carbonitride tends to have poor crystallinity and uniformity, and when it exceeds 2000 ° C., the obtained metal carbonitride tends to sinter. Tend.

Examples of the raw material oxides of metal A and metal Z include titanium oxide, zirconium oxide, vanadium oxide, niobium oxide, tantalum oxide, molybdenum oxide, and tungsten oxide. One or more kinds of metal oxides can be used. In addition, any of the above metal oxides may be used in the case where the existence of oxides having a plurality of metal valences is known.

Examples of the raw material carbide of metal A and carbide of metal Z include titanium carbide, zirconium carbide, vanadium carbide, niobium carbide, tantalum carbide, molybdenum carbide, tungsten carbide and the like. One or more kinds of metal carbides can be used.

Examples of the raw material metal A nitride and metal Z nitride include titanium nitride, zirconium nitride, vanadium nitride, niobium nitride, tantalum nitride, molybdenum nitride, and tungsten nitride. One or more kinds of metal nitrides can be used.

One or more compounds selected from the group consisting of a metal A oxide, a metal A nitride, and a metal A carbide, a metal Z oxide, the metal Z nitride, and the metal The total content of metal A and metal Z in the finally obtained metal carbonitride is controlled by controlling the amount of addition with one or more compounds selected from the group consisting of carbides of Z In addition, the content of each metal component can be within the specific range.

Whichever raw material is used, a catalyst composed of metal carbonitride obtained by heating the obtained metal carbonitride in an oxygen-containing inert gas has a high oxygen reduction starting potential and is active. .

By controlling the amount (molar ratio) of the oxides of the metals A and Z, the carbides of the metals A and Z, and the nitrides of the metals A and Z, an appropriate metal carbonitride can be obtained. The blending amount (molar ratio) is, for example, 0.01 to 500 moles of carbide and 0.01 to 50 moles of oxide with respect to 1 mole of nitride, and preferably 0.1 mole of nitride with respect to 1 mole. The carbide is 0.1 to 300 mol and the oxide is 0.1 to 30 mol. When a metal carbonitride produced at a blending molar ratio satisfying the above range is used as a raw material, an active metal carbonitride oxide tends to be obtained with a high oxygen reduction starting potential.

(Production process of metal carbonitride)
Next, a process for obtaining a metal carbonitride by heating the metal carbonitride obtained by the production methods (I) and (II) in an oxygen-containing inert gas will be described.

The inert gas includes helium gas, neon gas, argon gas, krypton gas, xenon gas, radon gas, or nitrogen gas. Argon gas or helium gas is particularly preferable because it is relatively easily available.

The oxygen gas concentration in the inert gas in this step depends on the heating time and the heating temperature, but is preferably 0.1 to 10% by volume, particularly preferably 0.5 to 5% by volume. When the oxygen gas concentration is within the above range, it is preferable in that a uniform carbonitride oxide is formed. Further, when the oxygen gas concentration is less than 0.1% by volume, it tends to be in an unoxidized state, and when it exceeds 10% by volume, oxidation tends to proceed excessively.

The heating temperature in this step is preferably in the range of 400 to 1400 ° C., and more preferably in the range of 600 to 1200 ° C. When the heating temperature is within the above range, it is preferable in that a uniform metal oxycarbonitride is formed. When the heating temperature is less than 400 ° C., the oxidation tends not to proceed, and when it exceeds 1400 ° C., the oxidation proceeds and the crystal tends to grow.

Examples of the heating method in the process include a stationary method, a stirring method, a dropping method, and a powder trapping method.

The stationary method is a method in which a metal carbonitride is placed in a stationary electric furnace and heated. There is also a method of heating by placing an alumina board, a quartz board or the like weighing metal carbonitride. The stationary method is preferable in that a large amount of metal carbonitride can be heated.

The stirring method is a method in which a metal carbonitride is placed in an electric furnace such as a rotary kiln and heated while stirring. The stirring method is preferable in that a large amount of metal carbonitride can be heated and aggregation and growth of metal carbonitride particles can be suppressed.

In the dropping method, the furnace is heated to a predetermined heating temperature while flowing an inert gas containing a small amount of oxygen gas in the induction furnace, and after maintaining the thermal equilibrium at the temperature, the crucible which is the heating area of the furnace In this method, metal carbonitride is dropped and heated. The dropping method is preferable in that aggregation and growth of metal carbonitride particles can be suppressed to a minimum.

The powder trapping method captures metal carbonitride in a vertical tube furnace maintained at a specified heating temperature by floating the metal carbonitride in an inert gas atmosphere containing a trace amount of oxygen gas. And heating.

In the drop method, the heating time of the metal carbonitride is usually 0.5 to 10 minutes, preferably 0.5 to 3 minutes. It is preferable that the heating time be within the above range because a uniform metal oxycarbonitride tends to be formed. When the heating time is less than 0.5 minutes, metal oxycarbonitride tends to be partially formed, and when it exceeds 10 minutes, oxidation tends to proceed excessively.

In the case of the powder trapping method, the heating time of the metal carbonitride is 0.2 seconds to 1 minute, preferably 0.2 to 10 seconds. It is preferable that the heating time be within the above range because a uniform metal oxycarbonitride tends to be formed. When the heating time is less than 0.2 seconds, metal oxycarbonitride tends to be partially formed, and when it exceeds 1 minute, oxidation tends to proceed excessively. When carried out in a tubular furnace, the heating time of the metal carbonitride is 0.1 to 10 hours, preferably 0.5 to 5 hours. It is preferable that the heating time be within the above range because a uniform metal oxycarbonitride tends to be formed. When the heating time is less than 0.1 hour, metal oxycarbonitride tends to be partially formed, and when it exceeds 10 hours, oxidation tends to proceed excessively.

As the catalyst of the present invention, the metal oxycarbonitride obtained by the above-described production method or the like may be used as it is, but the obtained metal oxycarbonitride is further pulverized into a finer powder. It may be used.

Examples of the method for crushing the metal carbonitride oxide include a roll rolling mill, a ball mill, a medium agitation mill, an airflow crusher, a mortar, a method using a tank disintegrator, and the like. The method using an airflow pulverizer is preferable, and the method using a mortar is preferable from the viewpoint that a small amount of processing is easy.

<Application>
The application of the catalyst realized by the present invention is not particularly limited, but as an example, when obtaining a target substance by introducing one or more kinds of reaction raw materials into a reaction vessel and changing pressure, temperature, etc. It may be used for the purpose of promoting the reaction. It is also possible to use for the purpose of accelerating the decomposition of the substance, for example, the use of accelerating the decomposition of the harmful substance or the decomposition of the upstream material for supplying the material.

When used as an electrode catalyst, it acts to lower the reaction overvoltage of the reduction reaction of oxygen or other compounds and increase the yield of the target substance with respect to the input electric energy. When used as an electrode catalyst, it can be used as a catalyst that lowers the operating overvoltage of the fuel cell. At this time, a fuel electrode (anode) that oxidizes fuel such as hydrogen or alcohol, or air that reduces oxygen or the like. Regardless of which electrode (cathode) is used, it is possible to exert its effect. Since the catalyst of the present invention is particularly excellent in high potential durability and has a large oxygen reducing ability, it is preferably used for the cathode catalyst layer.

The fuel cell catalyst layer of the present invention is characterized by containing the catalyst. The catalyst layer for a fuel cell of the present invention preferably further contains electron conductive particles.

When the fuel cell catalyst layer containing the catalyst further contains electron conductive particles, the reduction current can be further increased. The electron conductive particles are considered to increase the reduction current because they generate an electrical contact for inducing an electrochemical reaction in the catalyst.

The electron conductive particles are usually used as a catalyst carrier.

Examples of the electron conductive particles include carbon, conductive polymers, conductive ceramics, metals, and conductive inorganic oxides such as tungsten oxide and iridium oxide, and these can be used alone or in combination. In particular, since carbon is easily available with a small particle size at low cost and is excellent in chemical resistance and high potential resistance, carbon alone or a mixture of carbon and other electron conductive particles is preferable. That is, the fuel cell catalyst layer preferably contains the catalyst and carbon.

As the carbon, carbon black, graphite, graphite, activated carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, fullerene and the like can be used. If the particle size of the carbon is too small, it becomes difficult to form an electron conduction path, and if it is too large, the gas diffusibility of the catalyst layer for the fuel cell tends to be reduced or the utilization factor of the catalyst tends to be reduced. A range of 1000 nm is preferable, and a range of 10 to 100 nm is more preferable. In the present invention, the carbon particle diameter d is the average primary particle diameter obtained from the following formula (2) by converting the specific surface area S obtained by the BET method into a spherical shape.

d = 0.006 / (ρS) (2)
(In the formula (2), d is the average particle diameter (unit: nm), ρ is the true density of the particle (unit: g / cm ³ ), and S is the specific surface area of the particle (unit: m ² / g). )
Here, for simplicity, the true density of the carbon particles is set to 2.3 (g / cm ³ ).

When the electron conductive particles are carbon, the mass ratio of the catalyst to carbon (catalyst: electron conductive particles) is preferably 4: 1 to 1000: 1, more preferably 4.5: 1 to 200. : 1, more preferably 5: 1 to 100: 1.

The conductive polymer is not particularly limited. For example, polyacetylene, poly-p-phenylene, polyaniline, polyalkylaniline, polypyrrole, polythiophene, polyindole, poly-1,5-diaminoanthraquinone, polyaminodiphenyl, poly (o- Phenylenediamine), poly (quinolinium) salts, polypyridine, polyquinoxaline, polyphenylquinoxaline and the like. Among these, polypyrrole, polyaniline, and polythiophene are preferable, and polypyrrole is more preferable.

The polymer electrolyte is not particularly limited as long as it is generally used in a fuel cell catalyst layer. Specifically, a perfluorocarbon polymer having a sulfonic acid group (for example, NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521), etc.)), a hydrocarbon polymer having a sulfonic acid group. Compound, polymer compound doped with inorganic acid such as phosphoric acid, organic / inorganic hybrid polymer partially substituted with proton conductive functional group, polymer matrix with phosphoric acid solution or sulfuric acid solution, or ionic liquid And a proton conductor impregnated with. Among these, NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) is preferable.

The fuel cell catalyst layer of the present invention can be used for either an anode catalyst layer or a cathode catalyst layer. The catalyst layer for a fuel cell of the present invention includes a catalyst layer (catalyst catalyst for cathode) provided on the cathode of a fuel cell because it contains a catalyst having high oxygen reducing ability and hardly corroded even in a high potential in an acidic electrolyte. Layer). In particular, it is suitably used for a catalyst layer provided on the cathode of a membrane electrode assembly provided in a polymer electrolyte fuel cell.

Examples of the method for dispersing the catalyst on the electron conductive particles as a support include air flow dispersion and dispersion in liquid. Dispersion in liquid is preferable because a catalyst and electron conductive particles dispersed in a solvent can be used in the fuel cell catalyst layer forming step. Examples of the dispersion in the liquid include a method using an orifice contraction flow, a method using a rotating shear flow, and a method using an ultrasonic wave. The solvent used for dispersion in the liquid is not particularly limited as long as it does not erode the catalyst or electron conductive particles and can be dispersed, but a volatile liquid organic solvent or water is generally used. The

Further, when the catalyst is dispersed on the electron conductive particles, the electrolyte and the dispersant may be further dispersed at the same time.

The method for forming the catalyst layer for the fuel cell is not particularly limited. For example, a method of applying a suspension containing the catalyst, the electron conductive particles, and the electrolyte to an electrolyte membrane or a gas diffusion layer to be described later. It is done. Examples of the application method include a dipping method, a screen printing method, a roll coating method, and a spray method. In addition, after forming a catalyst layer for a fuel cell on a base material by a coating method or a filtration method using a suspension containing the catalyst, electron conductive particles, and an electrolyte, the catalyst layer for a fuel cell is formed on the electrolyte membrane by a transfer method. The method of forming is mentioned.

The electrode of the present invention is characterized by having the fuel cell catalyst layer and a porous support layer.

The electrode of the present invention can be used as either a cathode or an anode. Since the electrode of the present invention is excellent in durability and has a large catalytic ability, it is more effective when used for a cathode.

The porous support layer is a layer that diffuses gas (hereinafter also referred to as “gas diffusion layer”). The gas diffusion layer may be anything as long as it has electron conductivity, high gas diffusibility, and high corrosion resistance. Generally, carbon-based porous materials such as carbon paper and carbon cloth are used. Aluminum foil coated with stainless steel or corrosion resistant material is used for the material and weight reduction.

The membrane electrode assembly of the present invention is a membrane electrode assembly having a cathode, an anode, and an electrolyte membrane disposed between the cathode and the anode, wherein the cathode and / or the anode is the electrode. It is characterized by that.

As the electrolyte membrane, for example, an electrolyte membrane using a perfluorosulfonic acid system or a hydrocarbon electrolyte membrane is generally used. However, a membrane or porous body in which a polymer microporous membrane is impregnated with a liquid electrolyte is used. A membrane filled with a polymer electrolyte may be used.

The fuel cell of the present invention is characterized by comprising the membrane electrode assembly.

Fuel cell electrode reactions occur at the so-called three-phase interface (electrolyte-electrode catalyst-reaction gas). Fuel cells are classified into several types depending on the electrolyte used, and there are molten carbonate type (MCFC), phosphoric acid type (PAFC), solid oxide type (SOFC), solid polymer type (PEFC), etc. . Especially, it is preferable to use the membrane electrode assembly of this invention for a polymer electrolyte fuel cell.

The fuel cell using the catalyst of the present invention has high performance and is extremely inexpensive compared to the case where platinum is used as a catalyst. An article having at least one function selected from the group consisting of a power generation function, a light emission function, a heat generation function, a sound generation function, an exercise function, a display function, and a charging function, by taking advantage of the features thereof, is provided with the fuel cell, thereby providing performance. Can be improved. In particular, the performance of portable articles can be improved. The fuel cell is preferably provided on the surface or inside of an article.

Examples of the article that can include the fuel cell of the present invention include building materials, lighting equipment, design window glass, machines, vehicles, glass products, household appliances, agricultural materials, electronic devices, mobile phones, beauty instruments, and portable information terminals. , Tools, tableware, bath products, toilet products, furniture, clothing, fabric products, textiles, leather products, paper products, resin products, sports goods, futons, containers, glasses, signs, piping, wiring, metal fittings, sanitary materials, automotive supplies , Stationery, patches, hats, bags, shoes, umbrellas, blinds, balloons, lighting, light emitting diodes (LEDs), traffic lights, street lights, toys, road signs, ornaments, tents, traffic lights, bulletin boards, cooler boxes , Teaching materials, artificial flowers, objects, power supplies for heart pacemakers, power supplies for heaters with Peltier elements and power supplies for coolers with Peltier elements Ri article is at least one can be cited selected.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Further, various measurements in Examples and Comparative Examples were performed by the following methods.

[Analysis method]
1. Powder X-ray diffraction Samples were subjected to powder X-ray diffraction using a rotor flex made by Rigaku Corporation.

The number of diffraction line peaks in powder X-ray diffraction of each sample was counted by regarding a signal that can be detected with a ratio (S / N) of signal (S) to noise (N) of 10 or more as one peak. The noise (N) is the width of the baseline.

2. Elemental analysis Carbon: About 0.1 g of a sample was weighed and measured with a solid carbon analyzer (Horiba EMIA-110).

Nitrogen / oxygen: About 0.1 g of a sample was weighed and sealed in Ni-Cup, and then measured with an ON analyzer (TC600 manufactured by LECO).

Metal A, Metal Z: About 0.1 g of a sample was weighed on a platinum dish, and acid was added for thermal decomposition. The heat-decomposed product was fixed, diluted, and quantified with ICP-MS (ICP-OES VISTA-PRO) manufactured by SII.

[Example 1]
(1-1) Preparation of catalyst 7.62 g of zirconium carbide (ZrC, manufactured by High Purity Chemical Laboratory), 0.46 g of zirconium nitride (ZrN, manufactured by High Purity Chemical Laboratory) and tantalum pentoxide (Ta ₂ O ₅ , high 1.92 g (manufactured by Pure Chemical Laboratories) were mixed, pulverized, and heated at 1800 ° C. in a nitrogen atmosphere to obtain about 9.2 g of carbonitride (1) containing zirconium and tantalum.

The obtained carbonitride (1) is heated at 800 ° C. for 1 hour in a tubular furnace while flowing 1 g of argon gas containing 1% by volume of oxygen gas, thereby oxidizing carbonitriding containing zirconium and tantalum. 1.1 g of a product (hereinafter also referred to as “catalyst (1)”) was obtained. Table 1 shows the results of elemental analysis of the obtained catalyst (1).

The powder X-ray diffraction spectrum of the catalyst (1) is shown in FIG. An enlarged view of the diffraction angle 2θ = 33 ° to 43 ° is shown in FIG. Four diffraction line peaks were observed between the diffraction angle 2θ = 33 ° and 43 °.

(1-2) Production of Oxygen Reducing Ability Evaluation Electrode The oxygen reducing ability was measured as follows. Into 10 g of a solution prepared by mixing 0.095 g of the catalyst (1) obtained in (1-1) and 0.005 g of carbon (XC-72 manufactured by Cabot) at a mass ratio of isopropyl alcohol: pure water = 1: 1. The mixture was agitated with ultrasonic waves, suspended and mixed. 30 μl of this mixture was applied to a glassy carbon electrode (manufactured by Tokai Carbon Co., Ltd., diameter: 5.2 mm) and dried at 120 ° C. for 1 hour. Furthermore, 10 μl of NAFION (registered trademark) (DuPont 5% NAFION (registered trademark) solution (DE521)) diluted 10 times with pure water was applied, dried at 120 ° C. for 1 hour, and an electrode for a fuel cell ( 1) was obtained.

(1-3) Evaluation of oxygen reduction ability The catalytic ability (oxygen reduction ability) of the fuel cell electrode (1) produced in (1-2) was evaluated by the following method.

First, the prepared fuel cell electrode (1) was polarized in an oxygen atmosphere and a nitrogen atmosphere in a 0.5 mol / dm ³ sulfuric acid solution at 30 ° C. and a potential scanning rate of 5 mV / sec, and a current-potential curve was obtained. It was measured. At that time, a standard hydrogen electrode in a sulfuric acid solution having the same concentration was used as a reference electrode.

From the above measurement results, the potential at which a difference of 1.0 μA / cm ² or more appears between the reduction current in the oxygen atmosphere and the reduction current in the nitrogen atmosphere was defined as the oxygen reduction start potential, and the difference between the ^two was defined as the oxygen reduction current.

The catalytic ability (oxygen reducing ability) of the fuel cell electrode (1) produced by this oxygen reduction starting potential and oxygen reducing current was evaluated.

That is, the higher the oxygen reduction start potential and the larger the oxygen reduction current, the higher the catalytic ability (oxygen reducing ability) of the fuel cell electrode.

FIG. 17 shows current-potential curves in a nitrogen-saturated atmosphere and an oxygen-saturated atmosphere obtained by the above measurement.

The electrode for fuel cell (1) produced in Example 1 has an oxygen reduction starting potential of 0.81 V (vs. NHE) and was found to have a high oxygen reducing ability.

[Example 2]
(2-1) Preparation of catalyst 7.65 g of titanium carbide (TiC, manufactured by High-Purity Chemical Laboratory), 0.47 g of titanium nitride (TiN, manufactured by High-Purity Chemical) and niobium oxide (IV) (NbO ₂ , high-purity) About 9.5 g of carbonitride (2) containing titanium and niobium was obtained in the same manner as described in Example 1-1 (1-1) except that 1.88 g was used as a raw material. Moreover, about 1.1 g of carbonitride oxide (2) (hereinafter also referred to as “catalyst (2)”) containing titanium and niobium was obtained from 1 g of the obtained carbonitride (2).

Table 1 shows the results of elemental analysis of the obtained catalyst (2). Further, the powder X-ray diffraction spectrum of the catalyst (2) is shown in FIG. An enlarged view of the diffraction angle 2θ = 33 ° to 43 ° is shown in FIG. Six diffraction line peaks were observed between the diffraction angle 2θ = 33 ° and 43 °.

(2-2) Production of Fuel Cell Electrode A fuel cell electrode (2) was obtained in the same manner as in Example 1 except that the catalyst (2) was used.

(2-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (2) produced in (2-2) was used.

It was found that the fuel cell electrode (2) produced in Example 2 had an oxygen reduction starting potential of 0.73 V (vs. NHE) and high oxygen reducing ability.

[Example 3]
(3-1) Catalyst Preparation 6.69 g of titanium carbide (TiC, manufactured by High Purity Chemical Laboratory), 0.41 g of titanium nitride (TiN, manufactured by High Purity Chemical Laboratory) and niobium pentoxide (Nb ₂ O ₅₎ The carbonitride containing titanium and niobium (3) in the same manner as described in (1-1) of Example 1 except that 2.90 g was used. 5 g was obtained, and about 1.1 g of carbonitride oxide (hereinafter also referred to as “catalyst (3)”) containing titanium and niobium was obtained from 1 g of the obtained carbonitride (3).

Table 1 shows the results of elemental analysis of the obtained catalyst (3). Further, the powder X-ray diffraction spectrum of the catalyst (3) is shown in FIG. An enlarged view of the diffraction angle 2θ = 33 ° to 43 ° is shown in FIG. Four diffraction line peaks were observed between the diffraction angle 2θ = 33 ° and 43 °.

(3-2) Production of Fuel Cell Electrode A fuel cell electrode (3) was obtained in the same manner as in Example 1 except that the catalyst (3) was used.

(3-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (3) produced in (3-2) was used.

It was found that the fuel cell electrode (3) produced in Example 3 had an oxygen reduction starting potential of 0.71 V (vs. NHE) and high oxygen reducing ability.

[Example 4]
(4-1) Catalyst Preparation 7.67 g of titanium carbide (TiC, manufactured by High Purity Chemical Laboratory), 0.47 g of titanium nitride (TiN, manufactured by High Purity Chemical Laboratory) and zirconium oxide (ZrO ₂ , Jun Wako) The carbonitride containing titanium and zirconium (4) approximately 9.5 g in the same manner as described in Example 1-1 (1-1) except that 1.86 g manufactured by Yakuhin Kogyo Co., Ltd. was used. In addition, about 1.1 g of carbonitride oxide (hereinafter also referred to as “catalyst (4)”) containing titanium and zirconium was obtained from 1.0 g of the obtained carbonitride (4).

Table 1 shows the results of elemental analysis of the catalyst (4) obtained. Further, the powder X-ray diffraction spectrum of the catalyst (4) is shown in FIG. An enlarged view of the diffraction angle 2θ = 33 ° to 43 ° is shown in FIG. Four diffraction line peaks were observed between the diffraction angle 2θ = 33 ° and 43 °.

(4-2) Production of Fuel Cell Electrode A fuel cell electrode was obtained in the same manner as in Example 1 except that the catalyst (4) was used.

(4-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (4) produced in (4-2) was used.

It was found that the fuel cell electrode (4) produced in Example 4 had an oxygen reduction starting potential of 0.68 V (vs. NHE) and high oxygen reducing ability.

[Example 5]
(5-1) Preparation of catalyst As raw materials, zirconium carbide (ZrC, manufactured by High Purity Chemical Laboratory) 8.32 g, zirconium nitride (ZrN, manufactured by High Purity Chemical Laboratory) 0.50 g, and niobium oxide (IV) (NbO ₂ The same procedure described in Example 1-1 (1-1) except that 1.18 g was used and the heating temperature for obtaining the carbonitride was 1600 ° C. About 9.7 g of niobium-containing carbonitride (5) was obtained, and carbonitride oxide containing zirconium and niobium (hereinafter referred to as “catalyst (5)” from 1.0 g of the obtained carbonitride (5). Is also written.) About 1.0 g was obtained.

Table 1 shows the results of elemental analysis of the resulting catalyst (5). Further, the powder X-ray diffraction spectrum of the catalyst (5) is shown in FIG. An enlarged view of the diffraction angle 2θ = 33 ° to 43 ° is shown in FIG. Six diffraction line peaks were observed between the diffraction angle 2θ = 33 ° and 43 °.

(5-2) Production of Fuel Cell Electrode A fuel cell electrode (5) was obtained in the same manner as in Example 1 except that the catalyst (5) was used.

(5-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (5) produced in (5-2) was used.

The electrode for fuel cell (5) produced in Example 5 has an oxygen reduction starting potential of 0.73 V (vs. NHE) and was found to have a high oxygen reducing ability.

[Example 6]
(6-1) Catalyst Preparation 6.28 g of titanium oxide (TiO ₂ , manufactured by High Purity Chemical Laboratory), 1.18 g of niobium oxide (IV) (NbO ₂ , manufactured by High Purity Chemical Laboratory) and carbon (Cabot) Except for using 2.62 g of XC-72) manufactured by the same company, about 7.2 g of carbonitride (6) containing titanium and niobium was obtained in the same manner as described in (1-1) of Example 1. Moreover, about 1.0 g of carbonitride oxide (hereinafter also referred to as “catalyst (6)”) containing titanium and niobium was obtained from 1.0 g of the obtained carbonitride (6).

Table 1 shows the results of elemental analysis of the catalyst (6) obtained. FIG. 11 shows a powder X-ray diffraction spectrum of the catalyst (6), and FIG. 12 shows an enlarged view of the diffraction angle 2θ = 33 ° to 43 °. Four diffraction line peaks were observed between the diffraction angle 2θ = 33 ° and 43 °.

(6-2) Production of Fuel Cell Electrode A fuel cell electrode (6) was obtained in the same manner as in Example 1 except that the catalyst (6) was used.

(6-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (6) produced in (6-2) was used.

It was found that the fuel cell electrode (6) produced in Example 6 had an oxygen reduction starting potential of 0.70 V (vs. NHE) and high oxygen reducing ability.

[Example 7]
(7-1) Preparation of catalyst Molybdenum oxide (IV) (MoO ₂ , Wako Pure Chemical Industries) 6.81 g, tungsten oxide (VI) (WO ₃ , 99.5% Wako Pure Chemical Industries, Ltd.) as raw materials A carbonitride containing molybdenum and tungsten (7) in the same manner as described in Example 1-1 (1-1) except that 1.37 g and 2.62 g of carbon (XC-72 manufactured by Cabot) were used. About 8.0 g, and about 1.0 g of carbonitride oxide (hereinafter also referred to as “catalyst (7)”) containing molybdenum and tungsten from 1.0 g of the obtained carbonitride (7). Got.

Table 1 shows the results of elemental analysis of the resulting catalyst (7). In the powder X-ray diffraction spectrum of the catalyst (7), four diffraction line peaks were observed at a diffraction angle of 2θ = 33 ° to 43 °.

(7-2) Production of Fuel Cell Electrode A fuel cell electrode (7) was obtained in the same manner as in Example 1 except that the catalyst (7) was used.

(7-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (7) produced in (7-2) was used.

It was found that the fuel cell electrode (7) produced in Example 7 had an oxygen reduction starting potential of 0.71 V (vs. NHE) and high oxygen reducing ability.

[Example 8]
(8-1) Preparation of catalyst As raw materials, molybdenum (IV) oxide (MoO ₂ , Wako Pure Chemical Industries, Ltd.) 7.43 g, vanadium pentoxide (V) (V ₂ O ₅ , Wako Pure Chemical Industries, Ltd.) 0 Carbonitride (8) containing molybdenum and vanadium in the same manner as described in Example 1-1 (1-1) except that .58 g and 1.97 g of carbon (XC-72 manufactured by Cabot) were used. About 7.8 g was obtained, and about 1.1 g of carbonitride oxide (hereinafter also referred to as “catalyst (8)”) containing molybdenum and vanadium was obtained from 1.0 g of the obtained carbonitride (8). Obtained.

Table 1 shows the results of elemental analysis of the obtained catalyst (8). In the powder X-ray diffraction spectrum of the catalyst (8), four diffraction line peaks were observed at a diffraction angle of 2θ = 33 ° to 43 °.

(8-2) Production of Fuel Cell Electrode A fuel cell electrode (8) was obtained in the same manner as in Example 1 except that the catalyst (8) was used.

(8-3) Evaluation of oxygen reducing ability The catalytic ability (oxygen reducing ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (8) produced in (8-2) was used.

It was found that the fuel cell electrode (8) produced in Example 8 had an oxygen reduction starting potential of 0.71 V (vs. NHE) and high oxygen reducing ability.

[Example 9]
(9-1) Preparation of catalyst 8.21 g of titanium carbide (TiC, manufactured by High Purity Chemical Laboratory), 0.50 g of titanium nitride (TiN, manufactured by High Purity Chemical Laboratory) and titanium (IV) oxide (TiO ₂ , high Purified Chemical Research Laboratory Co., Ltd. (1.29 g) was mixed, pulverized, and heated at 1800 ° C. in a nitrogen atmosphere to obtain about 9.4 g of carbonitride (9-1-1) containing titanium. .

Apart from the above reaction, 8.33 g of niobium carbide (NbC, manufactured by High Purity Chemical Laboratory), 0.50 g of niobium nitride (NbN, manufactured by High Purity Chemical Laboratory) and niobium (IV) oxide (NbO ₂ , high purity chemical) 1.97 g (manufactured by Research Laboratory) was mixed, pulverized, and heated at 1800 ° C. in a nitrogen atmosphere to obtain about 9.7 g of carbonitride (9-1-2) containing niobium.

A sample obtained by mixing 0.5 g of the obtained carbonitride (9-1-1) and carbonitride (9-1-2) in a mortar, flowing argon gas containing 1% by volume of oxygen gas, By heating at 800 ° C. for 1 hour in a tubular furnace, about 1.1 g of carbonitride oxide (hereinafter also referred to as “catalyst (9)”) containing titanium and niobium was obtained.

Table 1 shows the results of elemental analysis of the obtained catalyst (9). From the powder X-ray diffraction spectrum of the catalyst (9), four diffraction line peaks were observed at a diffraction angle of 2θ = 33 ° to 43 °.

(9-2) Production of Fuel Cell Electrode A fuel cell electrode (9) was obtained in the same manner as in Example 1 except that the catalyst (9) was used.

(9-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (9) produced in (9-2) was used.

It was found that the fuel cell electrode (9) produced in Example 9 had an oxygen reduction starting potential of 0.70 V (vs. NHE) and high oxygen reducing ability.

[Comparative Example 1]
(10-1) Preparation of catalyst 8.37 g of tantalum carbide (TaC, manufactured by High Purity Chemical Laboratory), 0.50 g of tantalum nitride (TaN, manufactured by High Purity Chemical Laboratory) and tantalum (IV) oxide (TaO ₂ , high Purified Chemical Research Laboratories) 9.7 g of tantalum-containing carbonitride (10) was obtained in the same manner as described in Example 1-1 (1-1) except that 1.13 g was used as a raw material. Moreover, about 1.0 g of carbonitride oxide (hereinafter also referred to as “catalyst (10)”) containing tantalum was obtained from 1.0 g of the obtained carbonitride (10).

Table 1 shows the results of elemental analysis of the catalyst (10) obtained. The powder X-ray diffraction spectrum of the catalyst (10) is shown in FIG. An enlarged view of the diffraction angle 2θ = 33 ° to 43 ° is shown in FIG. Two diffraction line peaks were observed between the diffraction angle 2θ = 33 ° and 43 °.

(10-2) Production of Fuel Cell Electrode A fuel cell electrode (10) was obtained in the same manner as in Example 1 except that the catalyst (10) was used.

(10-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (10) produced in (10-2) was used.

FIG. 18 shows current-potential curves in a nitrogen saturated atmosphere and an oxygen saturated atmosphere obtained by the measurement.

The electrode for fuel cell (10) produced in Comparative Example 1 had an oxygen reduction starting potential of 0.59 V (vs. NHE).

[Comparative Example 2]
(11-1) Preparation of catalyst 8.33 g of zirconium carbide (ZrC, manufactured by High Purity Chemical Laboratory), 0.50 g of zirconium nitride (ZrN, manufactured by High Purity Chemical Laboratory) and zirconium (IV) oxide (ZrO ₂ , high About 9.6 g of carbonitride (11) containing zirconium was obtained in the same manner as described in Example 1-1 (1-1) except that 1.17 g was used as a raw material. About 1.0 g of carbonitride containing zirconium (hereinafter also referred to as “catalyst (11)”) was obtained from 1 g of the obtained carbonitride (11).

Table 1 shows the results of elemental analysis of the obtained catalyst (11). Further, the powder X-ray diffraction spectrum of the catalyst (11) is shown in FIG. An enlarged view of the diffraction angle 2θ = 33 ° to 43 ° is shown in FIG. Two diffraction line peaks were observed between the diffraction angle 2θ = 33 ° and 43 °.

(11-2) Production of Fuel Cell Electrode A fuel cell electrode (11) was obtained in the same manner as in Example 1 except that the catalyst (11) was used.

(11-3) Evaluation of oxygen reduction ability Catalytic ability (oxygen reduction ability) was evaluated in the same manner as in Example 1 except that the fuel cell electrode (11) produced in (11-2) was used.

The fuel cell electrode (11) produced in Comparative Example 2 had an oxygen reduction starting potential of 0.55 V (vs. NHE).

Table 2 shows the oxygen reduction characteristics of the catalysts in Examples 1 to 9 and Comparative Examples 1 and 2.

The catalyst of the present invention does not corrode in an acidic electrolyte or at a high potential, has excellent durability, and has a high oxygen reducing ability. Therefore, it can be used in a fuel cell catalyst layer, an electrode, an electrode assembly, or a fuel cell.

Claims (17)

0.2% by mass or more of one type of metal A selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten,
Containing 0.2% by mass or more of one kind of metal Z selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten (provided that metal Z is a metal different from metal A). And
And the total of the metal A and the metal Z is 25% by mass or more, and consists of a metal oxycarbonitride,
When the metal carbonitride is measured by powder X-ray diffraction (Cu-Kα ray), four or more diffraction line peaks are observed at a diffraction angle of 2θ = 33 ° to 43 °. And a catalyst. The metal oxycarbonitride is a mixture containing a oxycarbonitride containing metal A and a oxycarbonitride containing metal Z. 2. The catalyst according to claim 1, comprising 2% by mass or more and containing 0.2% by mass or more of metal oxynitride containing metal Z in terms of metal. The catalyst according to claim 1 or 2, wherein a molar ratio (metal A / metal Z) between the metal A and the metal Z is 1 or more and 15 or less. The combination of the metal A and the metal Z is the following (a) and (b), the following (a) and (c), or the following (b) and (c). A catalyst according to claim 1;
(A) One type of metal selected from the group consisting of titanium and zirconium (b) One type of metal selected from the group consisting of vanadium, niobium and tantalum (c) One type of metal selected from the group consisting of molybdenum and tungsten. The composition formula of the metal oxycarbonitride is A _a Z _b C _x N _y O _z (where A represents the metal A, Z represents the metal Z, and a, b, x, y, and z represent the number of atoms. 0.01 ≦ a <1, 0 <b ≦ 0.99, 0.01 ≦ x ≦ 2, 0.01 ≦ y ≦ 2, 0.01 ≦ z ≦ 3, a + b = 1, and The catalyst according to any one of claims 1 to 4, wherein x + y + z ≦ 5. A fuel cell catalyst layer comprising the catalyst according to any one of claims 1 to 5. The fuel cell catalyst layer according to claim 6, further comprising electron conductive particles. An electrode having a fuel cell catalyst layer and a porous support layer, wherein the fuel cell catalyst layer is the fuel cell catalyst layer according to claim 6 or 7. A membrane electrode assembly comprising a cathode, an anode, and an electrolyte membrane disposed between the cathode and the anode, wherein the cathode and / or the anode is an electrode according to claim 8. Membrane electrode assembly. A fuel cell comprising the membrane electrode assembly according to claim 9. A polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 9. 12. An article having at least one function selected from the group consisting of a power generation function, a light emission function, a heat generation function, a sound generation function, a movement function, a display function, and a charging function, comprising the fuel cell according to claim 10 or 11. Article characterized by being. The article is a building material, a lighting fixture, a design window glass, a machine, a vehicle, a glass product, a household appliance, an agricultural material, an electronic device, a mobile phone, a beauty appliance, a portable information terminal, a tool, tableware, a bath product, a toilet product, Furniture, clothing, fabric products, textiles, leather products, paper products, resin products, sports equipment, futons, containers, glasses, signs, piping, wiring, metal fittings, sanitary materials, automotive supplies, stationery, patches, hats, bags, shoes, Umbrellas, blinds, balloons, lighting, light-emitting diodes (LEDs), traffic lights, street lights, toys, road signs, ornaments, tents, traffic lights, bulletin boards, outdoor equipment, teaching materials, artificial flowers, objects, power supplies for heart pacemakers, Peltier elements The article according to claim 12, which is at least one selected from the group consisting of a power source for a heater provided and a power source for a cooler provided with a Peltier element. One type of metal A oxide selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten, and one type selected from the group consisting of titanium, zirconium, vanadium, niobium, tantalum, molybdenum and tungsten Metal carbonitride by heating a mixture of an oxide of metal Z (wherein metal Z is a different type of metal from metal A) and carbon in a nitrogen atmosphere in the range of 600 to 2000 ° C. Obtaining a product (ia);
A step (ii) of obtaining a metal carbonitride by heating the metal carbonitride in an oxygen-containing inert gas. A method for producing a catalyst. One or more compounds selected from the group consisting of the metal A oxide, the metal A nitride, and the metal A carbide, the metal Z oxide, the metal Z nitride, and the metal Z A mixture with one or more compounds selected from the group consisting of carbides (provided that the mixture contains at least carbides) in an inert gas (however, if the mixture does not contain nitrides, a nitrogen atmosphere) And (ib) to obtain a metal carbonitride by heating in the range of 600 to 2000 ° C.
A step (ii) of obtaining a metal carbonitride by heating the metal carbonitride in an oxygen-containing inert gas. A method for producing a catalyst. The method for producing a catalyst according to claim 14 or 15, wherein the heating temperature in the step (ii) is in the range of 400 to 1400 ° C. The method for producing a catalyst according to any one of claims 14 to 16, wherein the oxygen gas concentration in the step (ii) is in the range of 0.1 to 10% by volume.

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