JP2004217507A - Method of producing metal-containing active carbon - Google Patents
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- JP2004217507A JP2004217507A JP2003306198A JP2003306198A JP2004217507A JP 2004217507 A JP2004217507 A JP 2004217507A JP 2003306198 A JP2003306198 A JP 2003306198A JP 2003306198 A JP2003306198 A JP 2003306198A JP 2004217507 A JP2004217507 A JP 2004217507A
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Abstract
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本発明は、金属を含有する活性炭の製造方法並びに当該製造方法により製造された金属を含有する活性炭及びその用途に関する。 The present invention relates to a method for producing a metal-containing activated carbon, an activated carbon containing a metal produced by the production method, and a use thereof.
燃料電池は、環境に調和した高効率な発電システムとして注目を集めている。特にフッ素系イオン交換膜を電解質として使用する固体高分子電解質型燃料電池は、常温での作動が可能であり、かつ高出力密度であるため、排気ガスフリーの電気自動車用電源、家庭用電熱併給システムの電源等として幅広い実用化が期待されている。 Fuel cells are attracting attention as high-efficiency power generation systems that are in harmony with the environment. In particular, solid polymer electrolyte fuel cells that use a fluorine-based ion exchange membrane as the electrolyte can operate at room temperature and have a high output density, so they can be used for power supply for electric vehicles that are free of exhaust gas and for cogeneration with household electricity. It is expected to be widely used as a power source for systems.
このような燃料電池の実用化及び普及のためには、低コスト化が大きな課題となっている。既存の固体高分子電解質型燃料電池では、一般に電極触媒の成分に高価な白金を含むため、低コスト化のためには、白金使用量を低減する工夫が求められる。また白金の埋蔵量及び生産量にも限りがあり、将来的に普及が進んだ場合には、白金価格が高騰することも予想されるため、白金を用いない安価な電極触媒材料の開発も課題となっている。 For the practical use and spread of such fuel cells, cost reduction is a major issue. Existing solid polymer electrolyte fuel cells generally contain expensive platinum as a component of an electrode catalyst. Therefore, in order to reduce costs, a device for reducing the amount of platinum used is required. In addition, the amount of platinum reserves and production is limited, and if the use of platinum is widespread in the future, the price of platinum is expected to rise. Therefore, the development of inexpensive electrode catalyst materials that do not use platinum is also an issue. It has become.
従来、燃料電池の正極反応（酸素還元反応）を行う電極であって白金を用いないものとしては、例えば、非特許文献１に、金属を含む酵素を固定化した電極が報告されている。しかしながら、その電極活性は、電極触媒である白金微粒子を高分散担持した導電性カーボンブラックからなる電極と比較して非常に低いものである。また当該酵素を固体高分子電解質型燃料電池の電極に適用しても、強酸性の固体高分子中で加水分解が起こるため、その点からも、十分な電極活性は得られないと考えられる。
本発明は、固体高分子電解質型燃料電池の電極触媒材料として従来用いられている白金の使用量を著しく低減でき、又は白金に代えて使用できる、触媒活性が高く、且つ、安価な電極触媒材料を提供することを主な目的とする。 The present invention provides a highly catalytic and highly inexpensive electrocatalyst material that can significantly reduce the amount of platinum conventionally used as an electrocatalyst material for solid polymer electrolyte fuel cells, or can be used in place of platinum. The main purpose is to provide.
本発明者は、上記目的を達成すべく鋭意研究を重ねた結果、特定の製造方法により製造された活性炭が上記目的を達成できることを見出し、本発明を完成するに至った。 The present inventor has conducted intensive studies to achieve the above object, and as a result, has found that activated carbon manufactured by a specific manufacturing method can achieve the above object, and has completed the present invention.
即ち、本発明は、下記の金属を含有する活性炭の製造方法並びに当該製造方法により製造された活性炭及びその用途に係る。
１．金属を含有する有機天然物を、酸素量を制限した雰囲気で熱処理することを特徴とする金属を含有する活性炭の製造方法。
２．金属を含有する有機天然物が、金属を含有するタンパク質である上記項１記載の製造方法。
３．金属を含有するタンパク質が、鉄タンパク質及び銅タンパク質から選ばれる少なくとも１種である上記項２記載の製造方法。
４．熱処理後、さらに含フッ素有機酸及び／又はその塩を活性炭に添着する、上記項１〜３のいずれかに記載の製造方法。
５．含フッ素有機酸が、トリフルオロメタンスルホン酸（ＣＦ3ＳＯ3Ｈ）、トリフルオロメタンスルホンイミド（（ＣＦ3ＳＯ2）2ＮＨ）、トリフルオロメタンカルボン酸（ＣＦ3ＣＯＯＨ）及びパーフルオロエチレン−１，２−ビス−ホスホン酸（（ＯＨ）2ＯＰＣＦ2ＣＦ2ＰＯ（ＯＨ）2）から選ばれる少なくとも１種である上記項４記載の製造方法。
６．上記項１〜３のいずれかに記載の製造方法により製造された金属を含有する活性炭。
７．金属を含有し、含フッ素有機酸及び／又はその塩を添着したことを特徴とする活性炭。
８．上記項４又は５に記載の製造方法により製造された、金属を含有し、含フッ素有機酸及び／又はその塩を添着した活性炭。
９．上記項６〜８のいずれかに記載の活性炭を含有する酸素還元電極。
１０．上記項６〜８のいずれかに記載の活性炭を含有する電極触媒層を備えた固体高分子電解質型燃料電池の酸素還元電極。
１１．上記項１０記載の酸素還元電極を備えた固体高分子電解質型燃料電池。
１２．上記項６〜８のいずれかに記載の活性炭からなる調湿材料。
That is, the present invention relates to a method for producing activated carbon containing the following metals, activated carbon produced by the production method, and uses thereof.
1. A method for producing a metal-containing activated carbon, comprising heat-treating a metal-containing organic natural product in an atmosphere in which the amount of oxygen is restricted.
2.
3.
4. 4. The method according to any one of the above items 1 to 3, wherein after the heat treatment, a fluorinated organic acid and / or a salt thereof is further impregnated with the activated carbon.
5. Fluorinated organic acids, trifluoromethanesulfonic acid (CF 3 SO 3 H), trifluoromethane sulfonimide ((CF 3 SO 2) 2 NH), trifluoromethanesulfonic acid (CF 3 COOH) and perfluoro ethylene-1,2 - bis -
6. An activated carbon containing a metal produced by the production method according to any one of the above items 1 to 3.
7. Activated carbon containing a metal and impregnated with a fluorinated organic acid and / or a salt thereof.
8. 6. Activated carbon containing a metal and impregnated with a fluorinated organic acid and / or a salt thereof, produced by the production method according to the
9. Item 9. An oxygen reduction electrode containing the activated carbon according to any one of the
10. Item 9. An oxygen reduction electrode for a solid polymer electrolyte fuel cell comprising an electrode catalyst layer containing the activated carbon according to any one of
11. Item 11. A solid polymer electrolyte fuel cell comprising the oxygen reduction electrode according to
12.
本発明の製造方法によれば、賦活処理をしなくても十分に細孔が発達しており、比表面積が大きく、内部で金属が均一に分散している活性炭が製造できる。賦活処理を組み合わせる場合には、より比表面積の大きな活性炭を製造できる。 According to the production method of the present invention, it is possible to produce activated carbon in which pores are sufficiently developed, the specific surface area is large, and the metal is uniformly dispersed inside, without performing the activation treatment. When the activation treatment is combined, activated carbon having a larger specific surface area can be produced.
また、熱処理後、さらに含フッ素有機酸及び／又はその塩を活性炭に添着することにより、酸素還元性能の高い電極材料又は触媒材料として有用な活性炭を製造できる。 Further, after the heat treatment, a fluorine-containing organic acid and / or a salt thereof is further impregnated with the activated carbon, whereby an activated carbon useful as an electrode material or a catalyst material having high oxygen reduction performance can be produced.
このような本発明の活性炭は、酸素還元電極の材料として有用である。本発明の活性炭を含有する酸素還元電極は、酸素還元反応に対して高活性を示す。電極中の金属含有量を基準にして比較すると、白金担持カーボンブラック等を用いた従来の電極と同程度の活性を有している。また、本発明の活性炭は、酸素還元電極の材料として用いた場合に、電池効率の低下、材料の劣化等の原因となり得る中間体の過酸化水素の生成量が少ない点でも優れている。かかる酸素還元電極は、例えば、アルカリ型燃料電池、リン酸型燃料電池等の電極として有用である。その他、食塩電解層、空気亜鉛電池等の構成要素としても有用である。 Such activated carbon of the present invention is useful as a material for an oxygen reduction electrode. The oxygen reduction electrode containing the activated carbon of the present invention shows high activity for the oxygen reduction reaction. When compared on the basis of the metal content in the electrode, it has the same activity as a conventional electrode using platinum-supported carbon black or the like. Further, the activated carbon of the present invention is also excellent in that, when used as a material for an oxygen reduction electrode, a small amount of hydrogen peroxide is generated as an intermediate, which may cause a reduction in battery efficiency, deterioration of the material, and the like. Such an oxygen reduction electrode is useful, for example, as an electrode for an alkaline fuel cell, a phosphoric acid fuel cell, or the like. In addition, it is also useful as a component of a salt electrolyte layer, a zinc-air battery, and the like.
本発明の活性炭は、特に、固体高分子電解質型燃料電池の酸素還元電極の電極触媒材料としても有用である。本発明の活性炭を電極触媒に用いた固体高分子型電解質燃料電池の酸素還元電極は、電極触媒材料として従来用いられている白金を含まなくても、強酸性の固体高分子中において酸素還元反応に対して高活性を示す。触媒層中の金属含有量を基準に比較した場合、白金担持カーボンブラックなどを用いた従来の触媒層と同程度の活性を有している。また燃料電池の効率の低下、材料の劣化等の原因となり得る中間体の過酸化水素の生成量が少なく、白金を用いた電極と同様に直接水まで還元する能力を有する点で非常に優れている。 The activated carbon of the present invention is particularly useful as an electrode catalyst material for an oxygen reduction electrode of a solid polymer electrolyte fuel cell. The oxygen reduction electrode of a solid polymer electrolyte fuel cell using the activated carbon of the present invention as an electrode catalyst can perform oxygen reduction reaction in a strongly acidic solid polymer even without containing platinum conventionally used as an electrode catalyst material. Shows high activity. When compared with the metal content in the catalyst layer as a reference, it has the same activity as a conventional catalyst layer using platinum-supported carbon black or the like. In addition, it is extremely excellent in that the amount of hydrogen peroxide generated as an intermediate, which may cause a decrease in efficiency of the fuel cell and deterioration of the material, is small, and has an ability to directly reduce to water like an electrode using platinum. I have.
本発明の活性炭は、そのメカニズムは詳細には分からないが、優れた調湿性能を有している。従って、本発明の活性炭は調湿材料として有効に応用できると考えられる。 The activated carbon of the present invention has excellent humidity control performance, although its mechanism is not known in detail. Therefore, it is considered that the activated carbon of the present invention can be effectively applied as a humidity control material.
金属を含有する活性炭の製造方法
本発明の金属を含有する活性炭（以下「本発明の活性炭」と略記する場合がある）の製造方法は、金属を含有する有機天然物を、酸素量を制限した雰囲気で熱処理することを特徴とする。
Method for Producing Activated Carbon Containing Metal The method for producing activated carbon containing metal of the present invention (hereinafter sometimes abbreviated as “activated carbon of the present invention”) restricts the amount of oxygen from natural organic products containing metal. Heat treatment is performed in an atmosphere.
金属を含有する有機天然物としては特に限定されないが、例えば、金属を含有するタンパク質等が挙げられる。金属としては、鉄及び銅の少なくとも１種が好ましい。即ち、金属を含有する有機天然物としては、例えば、鉄タンパク質及び銅タンパク質から選ばれる少なくとも１種が好ましい。 The organic natural product containing a metal is not particularly limited, and examples thereof include a protein containing a metal. As the metal, at least one of iron and copper is preferable. That is, as the organic natural product containing a metal, for example, at least one selected from iron proteins and copper proteins is preferable.
鉄タンパク質としては特に限定されないが、例えば、カタラーゼ、ペルオキシダーゼ、ヒドロゲナーゼ、オキシゲナーゼ、シトクロム、ヘモグロビン、ミオグロビン、レグヘモグロビン、ヘモペキシン等のヘムタンパク質が挙げられる。また、ルブレドキシン、フェレドキシン、ニトロゲナーゼ、亜流酸レダクターゼ等の鉄−硫黄タンパク質を含む非ヘム鉄タンパク質も挙げられる。 Examples of the iron protein include, but are not particularly limited to, heme proteins such as catalase, peroxidase, hydrogenase, oxygenase, cytochrome, hemoglobin, myoglobin, leghemoglobin, and hemopexin. In addition, non-heme iron proteins including iron-sulfur proteins such as rubredoxin, ferredoxin, nitrogenase, and sulfite reductase are also included.
銅タンパク質としても特に限定されないが、例えば、ビリルビン・オキシダーゼ、ラッカーゼ、チロシナーゼ等が挙げられる。 The copper protein is not particularly limited, but includes, for example, bilirubin oxidase, laccase, tyrosinase and the like.
上記の中でも、鉄タンパク質が好ましく、特にヘムタンパク質が好ましい。本発明の製造方法では、金属を含有する有機天然物、特に上記タンパク質は、単独又は２種以上を混合して使用できる。金属を含有する有機天然物としては、上記タンパク質以外に、これらのタンパク質を含む血粉、これらのタンパク質を含む屠殺動物の廃棄物等も幅広く使用できる。 Among the above, iron proteins are preferred, and heme proteins are particularly preferred. In the production method of the present invention, metal-containing organic natural products, particularly the above proteins, can be used alone or in combination of two or more. As organic natural products containing metals, in addition to the above proteins, blood meals containing these proteins, wastes of slaughtered animals containing these proteins, and the like can also be used widely.
酸素量を制限した雰囲気としては特に限定されないが、例えば、下記（i）〜（v）のような雰囲気が挙げられる：
（i）アルゴン、窒素等の不活性ガスからなる不活性雰囲気、
（ii）水素等の還元性ガスからなる還元性雰囲気、
（iii）一般に活性炭の賦活処理に用いられる雰囲気であって、窒素、アルゴン等の不活性ガス中に水蒸気、二酸化炭素等を加えた雰囲気、
（iv）一般に活性炭の賦活処理に用いられる上記（iii）以外の雰囲気であって、有機天然物を燃焼させない程度まで酸素量を制限した雰囲気、
（v）一般の蒸し焼き時の雰囲気。
The atmosphere in which the amount of oxygen is restricted is not particularly limited, and examples thereof include the following atmospheres (i) to (v):
(I) an inert atmosphere composed of an inert gas such as argon or nitrogen;
(Ii) a reducing atmosphere composed of a reducing gas such as hydrogen,
(Iii) an atmosphere generally used for activation treatment of activated carbon, which is an atmosphere in which water vapor, carbon dioxide, or the like is added to an inert gas such as nitrogen or argon;
(Iv) an atmosphere other than the above (iii) generally used for the activation treatment of activated carbon, in which the amount of oxygen is limited to such an extent that organic natural products are not burned,
(V) General steaming atmosphere.
上記不活性ガス及び還元性ガスについては、単独又は２種以上を混合して使用できる。特に、上記（iii）又は（iv）の雰囲気で熱処理する場合には、賦活効果も得られるため、他の雰囲気で熱処理するよりも比表面積の大きな活性炭が得られる。 The above inert gas and reducing gas can be used alone or in combination of two or more. In particular, when heat treatment is performed in the above atmosphere (iii) or (iv), an activation effect is also obtained, and thus activated carbon having a larger specific surface area can be obtained than when heat treatment is performed in another atmosphere.
熱処理温度としては特に限定されないが、通常４００〜１２００℃、好ましくは６００〜９００℃程度である。熱処理時間は温度条件に応じて適宜設定できるが、通常３０分〜５時間、好ましくは１〜３時間程度である。但し、熱処理時間は、有機天然物の量、種類等に応じて適宜調整でき、必ずしも上記範囲に限定されない。 The heat treatment temperature is not particularly limited, but is usually 400 to 1200 ° C, preferably about 600 to 900 ° C. The heat treatment time can be appropriately set according to the temperature conditions, but is usually 30 minutes to 5 hours, preferably about 1 to 3 hours. However, the heat treatment time can be appropriately adjusted according to the amount, type, and the like of the organic natural product, and is not necessarily limited to the above range.
なお、本発明の製造方法では、上記熱処理後、水蒸気賦活法等の公知の賦活法により活性炭を賦活処理してもよい。また原料である有機天然物に、予め塩化亜鉛、炭酸ナトリウム等の公知の賦活剤を配合してもよい。これにより、得られる活性炭の比表面積をより増大することができる。
（含フッ素有機酸及び／又はその塩の添着）
本発明の製造方法では、上記熱処理後、さらに含フッ素有機酸及び／又はその塩を活性炭に添着してもよい。
In the production method of the present invention, after the heat treatment, activated carbon may be activated by a known activation method such as a steam activation method. A known activator such as zinc chloride or sodium carbonate may be previously added to the organic natural product as a raw material. Thereby, the specific surface area of the obtained activated carbon can be further increased.
(Impregnation of fluorinated organic acid and / or its salt)
In the production method of the present invention, after the heat treatment, a fluorinated organic acid and / or a salt thereof may be further impregnated on the activated carbon.
含フッ素有機酸としては特に限定されないが、例えば、トリフルオロメタンスルホン酸（ＣＦ3ＳＯ3Ｈ）、トリフルオロメタンスルホンイミド（（ＣＦ3ＳＯ2）2ＮＨ）、トリフルオロメタンカルボン酸（ＣＦ3ＣＯＯＨ）、パーフルオロエチレン−１，２−ビス−ホスホン酸（（ＯＨ）2ＯＰＣＦ2ＣＦ2ＰＯ（ＯＨ）2）等が挙げられる。これらの含フッ素有機酸又はその塩は、単独又は２種以上を混合して使用できる。 No particular limitation is imposed on the fluorine-containing organic acids, e.g., trifluoromethanesulfonic acid (CF 3 SO 3 H), trifluoromethane sulfonimide ((CF 3 SO 2) 2 NH), trifluoromethanesulfonic acid (CF 3 COOH), Perfluoroethylene-1,2-bis-phosphonic acid ((OH) 2 OPCF 2 CF 2 PO (OH) 2 ) and the like. These fluorinated organic acids or salts thereof can be used alone or in combination of two or more.
含フッ素有機酸及び／又はその塩を活性炭に添着させる際は、例えば、含フッ素有機酸及び／又はその塩の溶液中に活性炭を浸漬すればよい。その他、溶液を活性炭に噴霧する方法も挙げられる。溶液としては、水溶液又は有機溶剤溶液のいずれでもよい。 When impregnating the fluorinated organic acid and / or its salt with activated carbon, for example, the activated carbon may be immersed in a solution of the fluorinated organic acid and / or its salt. In addition, a method of spraying the solution on activated carbon is also included. The solution may be either an aqueous solution or an organic solvent solution.
浸漬法において、活性炭を溶液中に均一分散させるためには、特に、超音波振動撹拌等を行うことが好ましい。含フッ素有機酸及び／又はその塩の添着量としては、活性炭１００重量部に対して、通常０．０１〜５０重量部、好ましくは０．１〜４０重量部程度である。 In the dipping method, in order to uniformly disperse the activated carbon in the solution, it is particularly preferable to perform ultrasonic vibration stirring and the like. The amount of the fluorinated organic acid and / or salt thereof to be impregnated is usually about 0.01 to 50 parts by weight, preferably about 0.1 to 40 parts by weight, per 100 parts by weight of the activated carbon.
このように含フッ素有機酸及び／又はその塩を活性炭に添着することにより、活性炭を酸素還元電極の電極材料（例えば、電極触媒成分）として用いる場合に、添着しない場合に比して、高い酸素還元活性が得られる。尚、酸素還元電極の電極材料等に適用する場合には、使用中に含フッ素有機酸及び／又はその塩が電解液に溶出することを防ぐため、添着後の活性炭を高分子電解質により被覆することが好ましい。高分子電解質としては、含フッ素イオン交換樹脂等が挙げられる。 By impregnating the fluorinated organic acid and / or its salt to the activated carbon in this manner, when the activated carbon is used as an electrode material of the oxygen reduction electrode (for example, an electrode catalyst component), the oxygen content is higher than when no impregnation is performed. A reduction activity is obtained. When applied to an electrode material or the like of an oxygen reduction electrode, in order to prevent the fluorinated organic acid and / or its salt from being eluted into the electrolytic solution during use, the activated carbon after the impregnation is coated with a polymer electrolyte. Is preferred. Examples of the polymer electrolyte include a fluorinated ion exchange resin.
上記において、含フッ素有機酸塩を添着した場合には、添着後の含フッ素有機酸塩を含フッ素有機酸に転換することが好ましい。これは含フッ素有機酸塩よりも含フッ素有機酸の状態の方が、酸素還元性能が優れているからである。酸に転換する方法としては、例えば、カリウムイオン等を水素イオンにより置換すればよい。イオン置換操作は、例えば、含フッ素有機酸塩を過塩素酸水溶液、硫酸等の酸水溶液中に浸漬等することにより行える。 In the above, when a fluorinated organic acid salt is attached, it is preferable to convert the fluorinated organic acid salt after the attachment into a fluorinated organic acid. This is because the state of the fluorinated organic acid is more excellent in oxygen reduction performance than the state of the fluorinated organic acid salt. As a method for converting to an acid, for example, a potassium ion or the like may be replaced with a hydrogen ion. The ion replacement operation can be performed, for example, by immersing the fluorinated organic acid salt in an aqueous acid solution such as a perchloric acid aqueous solution or sulfuric acid.
金属を含有する活性炭
本発明の製造方法により製造された金属を含有する活性炭は、賦活処理をしない場合でも、細孔が十分に発達しており比表面積が大きい。かつ活性炭内部で活性中心となり得る金属又はその凝集体がほぼ均一に分散している。活性炭の賦活処理を行う場合には、より比表面積を大きくできる。このような活性炭（含フッ素有機酸／塩を添着しない場合）の多孔性の程度としては、概ね下記の通りである。
Activated carbon containing a metal The activated carbon containing a metal produced by the production method of the present invention has sufficiently developed fine pores and a large specific surface area even without activation treatment. In addition, a metal or an aggregate thereof which can be an active center in the activated carbon is substantially uniformly dispersed. When the activated carbon is activated, the specific surface area can be further increased. The degree of porosity of such activated carbon (when no fluorine-containing organic acid / salt is impregnated) is generally as follows.
比表面積としては、通常５００ｍ2／ｇ以上、大きいものであれば７００〜３０００ｍ2／ｇ程度である。なお、比表面積は、−１９６℃における窒素吸着等温線のＢＥＴプロットにより求めた値である。 The specific surface area, typically 500 meters 2 / g or more, 700~3000m 2 / g approximately as long as large. The specific surface area is a value determined by a BET plot of a nitrogen adsorption isotherm at -196 ° C.
細孔容積としては、通常０．１〜２ｃｍ3／ｇ、好ましくは０．３〜１ｃｍ3／ｇ程度である。なお、細孔容積は、−１９６℃における窒素の圧力が９４．３ＫＰａのときの窒素吸着量から求めた値である。 The pore volume is usually about 0.1 to 2 cm 3 / g, preferably about 0.3 to 1 cm 3 / g. The pore volume is a value determined from the amount of nitrogen adsorbed when the pressure of nitrogen at -196 ° C is 94.3 KPa.
平均細孔径としては、通常０．３〜５ｎｍ、好ましくは１〜４ｎｍ程度である。なお、平均細孔径（ｄ）は、細孔を円筒状であると仮定し、比表面積をＳ、細孔容積をＶとして、式：ｄ＝４Ｖ／Ｓから求めた値である。 The average pore diameter is usually about 0.3 to 5 nm, preferably about 1 to 4 nm. The average pore diameter (d) is a value obtained from the equation: d = 4V / S, where S is the specific surface area and V is the pore volume, assuming that the pores are cylindrical.
活性炭内部では金属が一部凝集する場合もあるが、活性中心はほぼ均一に分散していると考えられる。 Although the metal may partially aggregate inside the activated carbon, it is considered that the active centers are almost uniformly dispersed.
金属の分散量は、有機天然物の種類により一定ではないが、例えば、鉄タンパク質のカタラーゼを用いた場合には０．３〜２．５重量％程度であり、ヘモグロビンを用いた場合には１〜１０重量％程度である。 The dispersion amount of the metal is not constant depending on the kind of the organic natural product. For example, when the catalase of iron protein is used, it is about 0.3 to 2.5% by weight, and when the hemoglobin is used, it is 1%. About 10% by weight.
本発明の製造方法において、熱処理後に含フッ素有機酸及び／又はその塩を添着した場合には、金属を含有し、含フッ素有機酸及び／又はその塩を添着した活性炭となる。含フッ素有機酸及び／又はその塩の添着量は、上記の通り、活性炭１００重量部に対して、通常０．０１〜５０重量部、好ましくは０．１〜４０重量部程度である。 In the production method of the present invention, when a fluorinated organic acid and / or a salt thereof is attached after the heat treatment, the activated carbon becomes a carbon-containing activated carbon to which the fluorinated organic acid and / or a salt thereof is attached. As described above, the amount of the fluorinated organic acid and / or the salt thereof is usually 0.01 to 50 parts by weight, preferably about 0.1 to 40 parts by weight, based on 100 parts by weight of the activated carbon.
本発明の金属を含有する活性炭は、メカニズムは詳細には分かっていないが、優れた調湿性能を有している。例えば、温度２５℃の恒温室では、湿度が５５％以下になると湿気を放出し、湿度が９０％以上となると湿気を吸収する。但し、前記湿度の範囲は、調湿性能が確実に得られる範囲を示したものであり、他の範囲においても調湿効果は得られるものと考えられる。 Although the mechanism of the activated carbon containing the metal of the present invention is not known in detail, it has excellent humidity control performance. For example, in a constant temperature room at a temperature of 25 ° C., when the humidity becomes 55% or less, moisture is released, and when the humidity becomes 90% or more, moisture is absorbed. However, the range of the humidity indicates a range in which the humidity control performance can be reliably obtained, and it is considered that the humidity control effect can be obtained in other ranges.
調湿性能に関しては、本発明の金属を含有する活性炭の中でも、特に含フッ素有機酸及び／又はその塩を添着したものが高い性能を有している。また、含フッ素有機酸及び／又はその塩に代えて無機金属塩を添着した場合にも高い調湿性能が得られる。 Regarding the humidity control performance, among the activated carbons containing the metal of the present invention, those to which a fluorinated organic acid and / or a salt thereof are attached have particularly high performance. Also, high humidity control performance can be obtained when an inorganic metal salt is added in place of the fluorinated organic acid and / or its salt.
上記無機金属塩としては特に限定されず、例えば、塩化ナトリウム、炭酸ナトリウム、炭酸水素ナトリウム、硝酸ナトリウム、硫酸ナトリウム、塩化カリウム、塩化カルシウム等のアルカリ金属及びアルカリ土類金属の塩が挙げられる。かかる無機金属塩の添着量は特に限定的ではないが、含フッ素有機酸等の添着量と同様、通常０．０１〜５０重量部、好ましくは０．１〜４０重量部程度である。 The inorganic metal salt is not particularly limited, and examples thereof include alkali metal and alkaline earth metal salts such as sodium chloride, sodium carbonate, sodium hydrogen carbonate, sodium nitrate, sodium sulfate, potassium chloride, and calcium chloride. The amount of the inorganic metal salt to be added is not particularly limited, but is usually about 0.01 to 50 parts by weight, preferably about 0.1 to 40 parts by weight, like the amount of the fluorine-containing organic acid or the like.
無機金属塩の添着方法は特に限定されず、前記した含フッ素有機酸及び／又はその塩の添着方法に倣えばよいが、例えば、下記の手順による添着方法が好ましいものとして挙げられる。
（１）本発明の金属を含有する活性炭（何も添着していない）及び無機金属塩を所定割合で混合する、
（２）上記混合物に溶媒（例えば、水、メチルアルコール、エチルアルコール又はこれらの混合物等）を加えて撹拌することにより全体を均一相とする、次いで
（３）上記混合溶液の溶媒を除去（例えば、減圧及び／又は加熱により除去できる）することにより活性炭に無機金属塩を添着させる。
The method of applying the inorganic metal salt is not particularly limited, and may be similar to the above-described method of applying the fluorinated organic acid and / or a salt thereof. For example, the following method is preferable.
(1) Activated carbon (containing nothing) containing the metal of the present invention and an inorganic metal salt are mixed at a predetermined ratio.
(2) A solvent (for example, water, methyl alcohol, ethyl alcohol or a mixture thereof) is added to the above mixture, and the mixture is stirred to make the whole a homogeneous phase. (3) The solvent of the above mixed solution is removed (for example, , Reduced pressure and / or heating) to cause the activated metal to impregnate the inorganic metal salt.
本発明の金属を含有する活性炭の用途
本発明の活性炭は、十分に細孔が発達しているため比表面積が大きく、かつ活性炭内部で金属が均一に分散している特徴を活かして各種用途に適用できる。例えば、酸素還元電極の材料、固体高分子電解質型燃料電池の酸素還元電極の電極触媒材料、調湿材料等の用途が挙げられる。以下、これらの代表的な用途について説明する。
Uses of the activated carbon containing the metal of the present invention The activated carbon of the present invention has a large specific surface area due to sufficiently developed pores, and takes advantage of the fact that the metal is uniformly dispersed inside the activated carbon for various uses. Applicable. For example, it can be used as a material for an oxygen reduction electrode, an electrode catalyst material for an oxygen reduction electrode of a solid polymer electrolyte fuel cell, a humidity control material, and the like. Hereinafter, these typical uses will be described.
（酸素還元電極の材料）
本発明の金属を含有する活性炭は、酸素還元電極の材料として有用である。酸素還元電極の製造方法は特に限定されず、例えば、（１）本発明の活性炭、（２）テトラフルオロエチレン等の公知のバインダー、等を混合後、圧縮成形等して各種形状の酸素還元電極を製造できる。導電剤を用いる場合には、より電極活性を高めることができる。
(Material for oxygen reduction electrode)
The activated carbon containing the metal of the present invention is useful as a material for an oxygen reduction electrode. The method for producing the oxygen reduction electrode is not particularly limited. For example, after mixing (1) the activated carbon of the present invention, (2) a known binder such as tetrafluoroethylene, and the like, compression molding or the like is performed, and the oxygen reduction electrode having various shapes is mixed. Can be manufactured. When a conductive agent is used, the electrode activity can be further increased.
上記導電剤としては、一般にカーボンブラックが用いられる。カーボンブラックの大きさは、活性炭の性状等により異なるが、平均粒子径が７０ｎｍ以下、好ましくは１０〜６０ｎｍ程度のものを用いる。導電剤の使用量は特に限定されないが、活性炭１００重量部に対して、通常１〜２００重量部、好ましくは５〜１００重量部程度である。 Generally, carbon black is used as the conductive agent. The size of the carbon black varies depending on the properties of the activated carbon and the like, but one having an average particle diameter of 70 nm or less, preferably about 10 to 60 nm is used. Although the amount of the conductive agent is not particularly limited, it is generally about 1 to 200 parts by weight, preferably about 5 to 100 parts by weight, based on 100 parts by weight of the activated carbon.
本発明の活性炭を酸素還元電極の材料とする場合には、特に含フッ素有機酸及び／又はその塩を添着したものが好ましい。塩を添着した場合には、前記手法により、含フッ素有機酸塩を含フッ素有機酸に転換後、電極材料とすることが好ましい。活性炭に含フッ素有機酸が添着していることにより、電極のイオン伝導性及び酸素拡散性が高まる。即ち、従来品よりも電極効率の高い酸素還元電極を作製できる。 When the activated carbon of the present invention is used as a material for an oxygen reduction electrode, it is particularly preferable that the activated carbon is impregnated with a fluorinated organic acid and / or a salt thereof. When a salt is attached, it is preferable to convert the fluorinated organic acid salt into a fluorinated organic acid by the above-described method, and then use the resultant as an electrode material. When the activated carbon is impregnated with the fluorinated organic acid, the ion conductivity and oxygen diffusivity of the electrode are enhanced. That is, an oxygen reduction electrode having a higher electrode efficiency than conventional products can be manufactured.
尚、必要に応じて、本発明の活性炭を担体として、酸素還元反応に対して高活性を有する成分（例えば、金属成分）を担持させた後に電極形成することもできる。 In addition, if necessary, the activated carbon of the present invention may be used as a carrier, and a component having a high activity for an oxygen reduction reaction (for example, a metal component) may be supported to form an electrode.
このようにして製造された酸素還元電極は、酸素還元反応に対して高活性を示し、電極中の金属含有量を基準に比較した場合、白金担持カーボンブラック等を含む従来の電極と同程度の活性を有している。また燃料電池の効率の低下、材料の劣化等の原因となり得る中間体の過酸化水素の生成量が少ない点でも非常に優れている。かかる酸素還元電極は、例えば、アルカリ型燃料電池、リン酸型燃料電池等の燃料電池に好適に適用できる。また、食塩電解層、空気亜鉛電池等の構成要素としても適用できる。 The oxygen reduction electrode manufactured in this manner exhibits high activity for the oxygen reduction reaction, and is comparable to a conventional electrode containing platinum-supported carbon black and the like when compared with the metal content in the electrode. Has activity. It is also very excellent in that the amount of hydrogen peroxide produced as an intermediate, which can cause a decrease in the efficiency of the fuel cell and the deterioration of materials, is small. Such an oxygen reduction electrode can be suitably applied to a fuel cell such as an alkaline fuel cell and a phosphoric acid fuel cell. Further, the present invention can be applied as a component of a salt electrolytic layer, a zinc-air battery, or the like.
（固体高分子電解質型燃料電池の酸素還元電極の電極触媒材料）
本発明の金属を含有する活性炭は、特に固体高分子電解質型燃料電池の酸素還元電極の電極触媒材料として有用である。本発明の活性炭を用いた電極触媒の形成方法は特に限定されず、常法に従って形成できる。
(Electrode catalyst material for oxygen reduction electrode of solid polymer electrolyte fuel cell)
The activated carbon containing the metal of the present invention is particularly useful as an electrode catalyst material for an oxygen reduction electrode of a solid polymer electrolyte fuel cell. The method for forming the electrode catalyst using the activated carbon of the present invention is not particularly limited, and the electrode catalyst can be formed according to a conventional method.
例えば、イ）本発明の活性炭、ロ）公知の高分子電解質（含フッ素イオン交換樹脂等）の溶液を均一に混合して調製した電極触媒層形成用材料（触媒ペースト）を用いて、これを高分子電解質（イオン交換膜）に直接塗布して、塗付層を乾燥させることにより形成できる。 For example, using a material (catalyst paste) for forming an electrode catalyst layer prepared by uniformly mixing a solution of a) the activated carbon of the present invention, b) a solution of a known polymer electrolyte (such as a fluorine-containing ion exchange resin) and the like. It can be formed by directly applying to a polymer electrolyte (ion exchange membrane) and drying the applied layer.
また、イ）本発明の活性炭、ロ）カーボンブラック等の公知の導電剤、ハ）公知の高分子電解質（含フッ素イオン交換樹脂等）の溶液を均一に混合して調製した電極触媒層形成用材料（触媒ペースト）を用いて、これを高分子電解質（イオン交換膜）に直接塗付して、塗付層を乾燥させることにより形成できる。 Also, a) for forming an electrode catalyst layer prepared by uniformly mixing a solution of a known conductive agent such as a) the activated carbon of the present invention, b) carbon black, and the like; c) a known polymer electrolyte (such as a fluorinated ion exchange resin). It can be formed by directly applying a material (catalyst paste) to a polymer electrolyte (ion exchange membrane) and drying the applied layer.
電極触媒層を形成する方法としては、上記のように、１）高分子電解質表面に直接ペーストを塗付する方法だけでなく、２）テトラフルオロエチレンシート等のシート状基材上に触媒ペーストを塗布して触媒層を形成した後、イオン交換膜側に触媒層を転写する方法等も利用できる。 As a method for forming the electrode catalyst layer, as described above, not only 1) a method in which the paste is directly applied to the surface of the polymer electrolyte, but also 2) a method in which the catalyst paste is coated on a sheet-like base material such as a tetrafluoroethylene sheet. After coating to form a catalyst layer, a method of transferring the catalyst layer to the ion exchange membrane side or the like can also be used.
導電剤としては、前記（酸素還元電極の材料）の項目で説明したものが使用できる。このように導電剤を配合する場合には、より活性を高めることができる。また、前記同様、本発明の活性炭を担体として、酸素還元反応に対して高活性を有する成分（例えば、金属成分）を担持後に電極触媒を形成することもできる。 As the conductive agent, those described in the above item (Material for oxygen reduction electrode) can be used. When the conductive agent is blended as described above, the activity can be further enhanced. In the same manner as described above, the activated carbon of the present invention can be used as a carrier, and a component having a high activity for an oxygen reduction reaction (for example, a metal component) can be supported to form an electrode catalyst.
高分子電解質溶液としては、例えば、溶媒であるアルコール／水に含フッ素イオン交換樹脂を溶解させた公知の溶液を使用できる。なお、均一組成の触媒ペーストを調製するためには、特に超音波振動撹拌等を行うのが好ましい。 As the polymer electrolyte solution, for example, a known solution in which a fluorinated ion exchange resin is dissolved in alcohol / water as a solvent can be used. In order to prepare a catalyst paste having a uniform composition, it is particularly preferable to perform ultrasonic vibration stirring and the like.
次いで、形成された触媒層とカーボンペーパー等の多孔質導電性シート状基材とを接合することにより固体高分子電解質型燃料電池の酸素還元電極が作製できる。なお、多孔質導電性シート状基材上に触媒ペーストを塗布して触媒層を形成後、触媒層の面をイオン交換膜と接合する方法を採用してもよい。 Next, the formed catalyst layer and a porous conductive sheet-like base material such as carbon paper are joined to form an oxygen reduction electrode of a solid polymer electrolyte fuel cell. After the catalyst paste is formed on the porous conductive sheet-like substrate by applying the catalyst paste, a method of joining the surface of the catalyst layer to the ion exchange membrane may be adopted.
なお、本用途においても、本発明の活性炭の中でも、特に含フッ素有機酸及び／又はその塩を添着したものが好ましい。塩を添着した場合には、前記手法により、含フッ素有機酸塩を含フッ素有機酸とした後、触媒形成することが好ましい。活性炭に含フッ素有機酸が添着していることにより、触媒の細孔中のイオン導電性と酸素拡散性が高まる。即ち、従来品よりも酸素還元性能の高い電極触媒が得られる。 In the present application, among the activated carbons of the present invention, those to which a fluorinated organic acid and / or a salt thereof are attached are particularly preferable. When a salt is attached, it is preferable to convert the fluorinated organic acid salt into a fluorinated organic acid by the above-described method and then form a catalyst. Since the fluorinated organic acid is impregnated on the activated carbon, the ionic conductivity and oxygen diffusivity in the pores of the catalyst are increased. That is, an electrode catalyst having higher oxygen reduction performance than conventional products can be obtained.
このようにして製造された固体高分子電解質型燃料電池の酸素還元電極は、従来触媒成分として用いられている白金を含まなくても、強酸性の固体高分子中において酸素還元反応に対して高活性を示す。触媒層中の金属含有量を基準に比較した場合、白金担持カーボンブラックなどを用いた従来の触媒層と同程度の活性を有している。また燃料電池の効率の低下、材料の劣化等の原因となり得る中間体の過酸化水素の生成量が少なく、白金を用いた電極と同様に直接水まで還元する能力を有する点で非常に優れている。 The oxygen reduction electrode of the solid polymer electrolyte fuel cell manufactured as described above has a high resistance to oxygen reduction reaction in a strongly acidic solid polymer even without containing platinum conventionally used as a catalyst component. Show activity. When compared with the metal content in the catalyst layer as a reference, it has the same activity as a conventional catalyst layer using platinum-supported carbon black or the like. In addition, it is extremely excellent in that the amount of hydrogen peroxide generated as an intermediate, which may cause a decrease in efficiency of the fuel cell and deterioration of the material, is small, and has an ability to directly reduce to water like an electrode using platinum. I have.
（調湿材料）
本発明の金属を含有する活性炭は、そのメカニズムは詳細には分からないが、前記した通り、優れた調湿性能を有している。その中でも、特に含フッ素有機酸及び／又はその塩を添着した活性炭、並びに無機金属塩を添着した活性炭は優れた調湿性能を有している。従って、本発明の活性炭は調湿材料として有効に応用できると考えられる。
(Humidity control material)
Although the mechanism of the activated carbon containing a metal of the present invention is not known in detail, it has excellent humidity control performance as described above. Among them, particularly activated carbon impregnated with a fluorinated organic acid and / or a salt thereof, and activated carbon impregnated with an inorganic metal salt have excellent humidity control performance. Therefore, it is considered that the activated carbon of the present invention can be effectively applied as a humidity control material.
以下に実施例及び比較例を示し、本発明をより具体的に説明する。但し、本発明は実施例に限定されない。 Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to the embodiments.
実施例１ａ
（金属を含有する活性炭の製造）
金属を含有する有機天然物であるカタラーゼを原料とした。原料を不活性ガスのアルゴン中、昇温速度５℃／ｍｉｎで８００℃まで加熱後、８００℃で２時間熱処理を行った。得られた金属を含有する活性炭のＸ線回折スペクトルを図１に示す。
Example 1a
(Production of activated carbon containing metal)
Catalase, a metal-containing organic natural product, was used as a raw material. The raw material was heated to 800 ° C. at a rate of 5 ° C./min in an inert gas of argon, and then heat-treated at 800 ° C. for 2 hours. FIG. 1 shows an X-ray diffraction spectrum of the activated carbon containing the obtained metal.
得られた金属を含有する活性炭について、熱処理前後の質量変化から収率を求めた。また灰分を求めた。さらに活性炭を粉砕後、窒素の吸着等温線を測定することにより、比表面積、細孔容積及び平均細孔径を求めた。これらの結果を下記表１に示す。
（電極触媒層の形成）
粉砕した活性炭１００ｍｇを０．５ｍｏｌ／ｌトリフルオロメタンスルホン酸カリウム（ＣＦ3ＳＯ3Ｋ）水溶液５ｍｌ中に入れ、超音波により分散させて活性炭にＣＦ3ＳＯＫを添着させた。
The yield of the obtained activated carbon containing metal was determined from the change in mass before and after the heat treatment. Ash content was also determined. Furthermore, after pulverizing the activated carbon, the specific surface area, the pore volume and the average pore diameter were determined by measuring the adsorption isotherm of nitrogen. The results are shown in Table 1 below.
(Formation of electrode catalyst layer)
100 mg of the pulverized activated carbon was put into 5 ml of a 0.5 mol / l aqueous solution of potassium trifluoromethanesulfonate (CF 3 SO 3 K), dispersed by ultrasonic waves, and CF 3 SOK was attached to the activated carbon.
次いで、遠心分離により上澄み液を除去後、５重量％パーフルオロスルホン酸樹脂溶液（アルドリッチ社製）１ｍｌ、カーボンブラック（商標名「Ｖｕｌｃａｎ ＸＣ−７２Ｒ」キャボット社製）１０ｍｇを加えて超音波により分散させて触媒ペーストを調製した。 Then, after removing the supernatant by centrifugation, 1 ml of a 5% by weight perfluorosulfonic acid resin solution (manufactured by Aldrich) and 10 mg of carbon black (trade name “Vulcan XC-72R” manufactured by Cabot) are added and dispersed by ultrasonic waves. Thus, a catalyst paste was prepared.
触媒ペースト１μｌを回転グラッシーカーボンディスク電極（塗布面積０．０７１ｃｍ2）に塗布し、十分に乾燥して触媒層前駆体を形成した。触媒層前駆体を０．１ｍｏｌ／ｌ過塩素酸水溶液に浸漬し、前駆体中のカリウムイオンを水素イオンに置換して触媒層を形成した。 1 μl of the catalyst paste was applied to a rotating glassy carbon disk electrode (application area: 0.071 cm 2 ) and dried sufficiently to form a catalyst layer precursor. The catalyst layer precursor was immersed in a 0.1 mol / l aqueous solution of perchloric acid, and potassium ions in the precursor were replaced with hydrogen ions to form a catalyst layer.
触媒層を形成した回転電極を酸素で飽和した０．１ｍｏｌ／ｌ過塩素酸水溶液中に浸漬し、可逆水素電極（ＲＨＥ）を参照極として酸素還元電流と電極電位との関係を調べた。当該関係を図２に示す。 The rotating electrode on which the catalyst layer was formed was immersed in a 0.1 mol / l aqueous solution of perchloric acid saturated with oxygen, and the relationship between the oxygen reduction current and the electrode potential was examined using a reversible hydrogen electrode (RHE) as a reference electrode. FIG. 2 shows the relationship.
触媒層の酸素還元反応に対する活性評価及び酸素１分子あたりの反応電子数の測定を、回転電極法に準拠して行った。回転電極法は、例えば「ジャーナル・オブ・ザ・エレクトロケミカル・ソサイアティー、第１４５巻、１９９８年、第３７１３頁」、「ジャーナル・オブ・ザ・エレクトロケミカル・ソサイアティー、第１４６巻、１９９９年、第１２９６頁」等において、固体高分子電解質型燃料電池の電極触媒活性の評価に有効であり、且つ、燃料電池性能と良好な相関性があることが報告されている。酸素１分子あたりの反応電子数を下記表２に示す。 Evaluation of the activity of the catalyst layer for the oxygen reduction reaction and measurement of the number of reaction electrons per oxygen molecule were performed according to the rotating electrode method. The rotating electrode method is described in, for example, “Journal of the Electrochemical Society, Vol. 145, 1998, p. 3713”, “Journal of the Electrochemical Society, Vol. 146, 1999, Vol. 1296 ”and the like report that it is effective in evaluating the electrode catalyst activity of a solid polymer electrolyte fuel cell and has good correlation with fuel cell performance. The number of reaction electrons per oxygen molecule is shown in Table 2 below.
実施例１ｂ
実施例１ａで用いたＣＦ3ＳＯ3Ｋ水溶液に代えて超純水を用いた（活性炭に含フッ素有機酸を添着しない）以外は、実施例１ａと同様にして触媒層を形成した。
Example 1b
A catalyst layer was formed in the same manner as in Example 1a, except that ultrapure water was used instead of the CF 3 SO 3 K aqueous solution used in Example 1a (no activated carbon was impregnated with a fluorinated organic acid).
実施例１ａと同様にして、触媒層を形成した回転電極について、酸素還元電流と電極電位との関係を調べた。当該関係を図２に示す。 In the same manner as in Example 1a, the relationship between the oxygen reduction current and the electrode potential was examined for the rotating electrode on which the catalyst layer was formed. FIG. 2 shows the relationship.
実施例１ａと同様にして、触媒層の酸素１分子あたりの反応電子数を測定した。酸素１分子あたりの反応電子数を下記表２に示す。 In the same manner as in Example 1a, the number of reaction electrons per oxygen molecule of the catalyst layer was measured. The number of reaction electrons per oxygen molecule is shown in Table 2 below.
実施例２ａ
（金属を含有する活性炭の製造）
金属を含有する有機天然物であるヘモグロビンを原料とした。原料を不活性ガスのアルゴン中、昇温速度５℃／ｍｉｎで８２５℃まで加熱後、８２５℃で２時間熱処理を行った。得られた金属を含有する活性炭のＸ線回折スペクトルを図３に示す。
Example 2a
(Production of activated carbon containing metal)
Hemoglobin, an organic natural product containing metals, was used as a raw material. The raw material was heated to 825 ° C. at a rate of 5 ° C./min in an inert gas of argon, and then heat-treated at 825 ° C. for 2 hours. FIG. 3 shows an X-ray diffraction spectrum of the activated carbon containing the obtained metal.
得られた金属を含有する活性炭について、熱処理前後の質量変化から収率を求めた。また灰分を求めた。さらに活性炭を粉砕後、窒素の吸着等温線を測定することにより、比表面積、細孔容積及び平均細孔径を求めた。これらの結果を下記表１に示す。
（電極触媒層の形成）
実施例１ａで用いた０．５ｍｏｌ／ｌＣＦ3ＳＯ3Ｋ水溶液に代えて０．１ｍｏｌ／ｌＣＦ3ＳＯ3Ｋ水溶液を用いる以外は実施例１ａと同様に触媒層を形成した。
The yield of the obtained activated carbon containing metal was determined from the change in mass before and after the heat treatment. Ash content was also determined. Furthermore, after pulverizing the activated carbon, the specific surface area, the pore volume and the average pore diameter were determined by measuring the adsorption isotherm of nitrogen. The results are shown in Table 1 below.
(Formation of electrode catalyst layer)
A catalyst layer was formed in the same manner as in Example 1a except that an aqueous solution of 0.1 mol / l CF 3 SO 3 K was used instead of the aqueous solution of 0.5 mol / l CF 3 SO 3 K used in Example 1a.
実施例１ａと同様にして、触媒層を形成した回転電極について、酸素還元電流と電極電位との関係を調べた。当該関係を図２に示す。 In the same manner as in Example 1a, the relationship between the oxygen reduction current and the electrode potential was examined for the rotating electrode on which the catalyst layer was formed. FIG. 2 shows the relationship.
実施例１ａと同様にして、触媒層の酸素１分子あたりの反応電子数を測定した。酸素１分子あたりの反応電子数を下記表２に示す。 In the same manner as in Example 1a, the number of reaction electrons per oxygen molecule of the catalyst layer was measured. The number of reaction electrons per oxygen molecule is shown in Table 2 below.
実施例２ｂ
実施例２ａで用いたＣＦ3ＳＯ3Ｋ水溶液に代えて超純水を用いた（活性炭に含フッ素有機酸を添着しない）以外は、実施例２ａと同様にして触媒層を形成した。
Example 2b
A catalyst layer was formed in the same manner as in Example 2a, except that ultrapure water was used instead of the aqueous CF 3 SO 3 K solution used in Example 2a (no activated carbon was impregnated with a fluorinated organic acid).
実施例１ａと同様にして、触媒層を形成した回転電極について、酸素還元電流と電極電位との関係を調べた。当該関係を図２に示す。 In the same manner as in Example 1a, the relationship between the oxygen reduction current and the electrode potential was examined for the rotating electrode on which the catalyst layer was formed. FIG. 2 shows the relationship.
実施例１ａと同様にして、触媒層の酸素１分子あたりの反応電子数を測定した。酸素１分子あたりの反応電子数を下記表２に示す。 In the same manner as in Example 1a, the number of reaction electrons per oxygen molecule of the catalyst layer was measured. The number of reaction electrons per oxygen molecule is shown in Table 2 below.
（電極触媒層の形成）
活性炭を入れずに、カーボンブラック（商標名「Ｖｕｌｃａｎ ＸＣ−７２Ｒ」キャボット社製）１０ｍｇのみを５重量％パーフルオロスルホン酸樹脂溶液（アルドリッチ社製）１ｍｌ中に入れて超音波により分散させて触媒ペーストを調製した。
(Formation of electrode catalyst layer)
Without adding activated carbon, only 10 mg of carbon black (trade name “Vulcan XC-72R” manufactured by Cabot Corporation) was placed in 1 ml of a 5% by weight perfluorosulfonic acid resin solution (manufactured by Aldrich) and dispersed by ultrasonic waves to form a catalyst. A paste was prepared.
触媒ペースト１μｌを回転グラッシーカーボンディスク電極（塗布面積０．０７１ｃｍ2）に塗布し、十分に乾燥して触媒層を形成した。 1 μl of the catalyst paste was applied to a rotating glassy carbon disk electrode (application area: 0.071 cm 2 ) and dried sufficiently to form a catalyst layer.
実施例１ａと同様にして、触媒層を形成した回転電極について、酸素還元電流と電極電位との関係を調べた。当該関係を図２に示す。 In the same manner as in Example 1a, the relationship between the oxygen reduction current and the electrode potential was examined for the rotating electrode on which the catalyst layer was formed. FIG. 2 shows the relationship.
比較例２
比較例１で用いたカーボンブラックに代えて白金１０重量％担持させたカーボンブラック（エレクトロケム社製）を用いた以外は比較例２と同様に触媒層を形成した。
Comparative Example 2
A catalyst layer was formed in the same manner as in Comparative Example 2 except that carbon black (manufactured by Electrochem) supporting 10% by weight of platinum was used instead of the carbon black used in Comparative Example 1.
実施例１ａと同様にして、触媒層を形成した回転電極について、酸素還元電流と電極電位との関係を調べた。当該関係を図２に示す。 In the same manner as in Example 1a, the relationship between the oxygen reduction current and the electrode potential was examined for the rotating electrode on which the catalyst layer was formed. FIG. 2 shows the relationship.
表及び図の結果
表１からは、本発明の金属を含有する活性炭は、賦活処理がされていないにも拘わらず、十分に細孔が発達して大きな比表面積を有することが分かる。図１からは、結晶として凝集しているのは不純物として含まれるシリカのみで、活性成分の鉄は全く凝集していないことが分かる。図３からは、鉄が酸化鉄の結晶として凝集していることが分かるが、ピークの形状から凝集の程度は小さいことが分かる。
Table 1 shows that the activated carbon containing the metal of the present invention has sufficient pores and a large specific surface area, though the activation treatment has not been performed. From FIG. 1, it can be seen that only the silica contained as an impurity is agglomerated as crystals, and iron as an active ingredient is not aggregated at all. From FIG. 3, it can be seen that iron is aggregated as iron oxide crystals, but the degree of aggregation is small from the shape of the peak.
表２からは、酸素１分子あたりの反応電子数が、直接水まで還元される場合の反応電子数である４と比較すると、本発明の金属を含有する活性炭を用いた酸素還元電極では、反応電子数２に相当する中間体の過酸化水素の生成が少なく、直接水まで還元する能力を有していることが分かる。図２からは、本発明の金属を含有する活性炭を含む触媒層が優れた酸素還元性能を有し、金属含有量が同程度の白金担持カーボンブラックを用いた従来の触媒層にも匹敵する活性を有していることが分かる。 From Table 2, when the number of reaction electrons per molecule of oxygen is compared with 4 which is the number of reaction electrons when directly reduced to water, the oxygen reduction electrode using activated carbon containing a metal of the present invention shows that It can be seen that the production of intermediate hydrogen peroxide corresponding to the number of electrons of 2 is small and that it has the ability to directly reduce to water. FIG. 2 shows that the catalyst layer containing the activated carbon containing the metal of the present invention has excellent oxygen reduction performance, and has an activity comparable to that of a conventional catalyst layer using platinum-supported carbon black having the same metal content. It can be seen that this has
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| US10573901B2 (en) | 2013-04-25 | 2020-02-25 | Tanaka Kikinzoku Kogyo K.K. | Catalyst and manufacturing method thereof, and electrode catalyst layer using the catalyst |
| US11031604B2 (en) | 2013-04-25 | 2021-06-08 | Nissan Motor Co., Ltd. | Catalyst and electrode catalyst layer, membrane electrode assembly, and fuel cell using the catalyst |
| US10320020B2 (en) | 2014-10-29 | 2019-06-11 | Nissan Motor Co., Ltd. | Electrode catalyst for fuel cell, electrode catalyst layer for fuel cell, method for producing the same, and membrane electrode assembly and fuel cell using the catalyst layer |
| US10367218B2 (en) | 2014-10-29 | 2019-07-30 | Nissan Motor Co., Ltd. | Electrode catalyst layer for fuel cell, method for producing the same, and membrane electrode assembly and fuel cell using the catalyst layer |
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