JP2007026952A - Method of manufacture for catalyst mixture for polymer electrolyte fuel cell and polymer electrolyte fuel cell using it - Google Patents

Method of manufacture for catalyst mixture for polymer electrolyte fuel cell and polymer electrolyte fuel cell using it Download PDF

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JP2007026952A
JP2007026952A JP2005208836A JP2005208836A JP2007026952A JP 2007026952 A JP2007026952 A JP 2007026952A JP 2005208836 A JP2005208836 A JP 2005208836A JP 2005208836 A JP2005208836 A JP 2005208836A JP 2007026952 A JP2007026952 A JP 2007026952A
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exchange resin
cation exchange
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fuel cell
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Yoshinobu Yasunaga
好伸 安永
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GS Yuasa Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for making distribution of cation-exchange resin on a carbon particle surface to be as uniform as possible in the manufacturing method for an excessively small amount of metal-supported catalyst and to provide a polymer electrolyte fuel cell (PEFC) with remarkably improved initial function by using the catalyst mixture obtained by this manufacturing method. <P>SOLUTION: The manufacturing method for the catalyst mixture for the polymer electrolyte fuel cell is composed of a first process obtaining a mixture X of carbon and cation-exchange resin by spray drying a mixture with the cation-exchange resin, a second process having positive ion in catalytic metal element adsorb to fixed ion in the cation-exchange resin of the mixture X, a third process obtaining a mixture Y by chemically reducing the positive ion in the catalytic metal element and a fourth process spray drying the mixture of the mixture Y and the cation-exchange resin solution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、固体高分子形燃料電池用触媒混合体の製造方法およびこの製造方法によって得られた触媒混合体を含む電極を備える固体高分子形燃料電池に関するものである。   The present invention relates to a method for producing a catalyst mixture for a polymer electrolyte fuel cell and a polymer electrolyte fuel cell comprising an electrode containing the catalyst mixture obtained by this production method.

固体高分子形燃料電池（ＰＥＦＣ）は、固体高分子電解質膜の一方の面にアノ−ドを、他の面にカソ−ドを接合して構成される。例えば、アノ−ドに燃料として水素、カソ−ドに酸化剤として酸素をそれぞれ供給すると、つぎの電気化学反応が起こる。   A polymer electrolyte fuel cell (PEFC) is constructed by joining an anode to one surface of a solid polymer electrolyte membrane and a cathode to the other surface. For example, when hydrogen is supplied to the anode as a fuel and oxygen is supplied to the cathode as an oxidant, the following electrochemical reaction occurs.

アノ−ド：２Ｈ２→４Ｈ＋＋４ｅ−
カソ−ド：Ｏ２＋４Ｈ＋＋４ｅ−→２Ｈ２Ｏ
固体高分子形燃料電池のアノ−ドおよびカソ−ドは、いずれもガス拡散層と触媒層とからなり、触媒層が固体高分子電解質膜に接合された構造である。触媒層には白金族金属触媒が含まれ、上記電気化学反応はこの触媒層で進行する。触媒層と接したガス拡散層は、触媒層への反応ガスの供給と集電との機能をもつ。さらに、カソード側での反応によって生成する水は、ガス拡散層を介して排出される。したがって、ガス拡散層には、ガス透過性、導電性および撥水性が要求される。また、触媒層にも、反応生成物である水が滞留しないように撥水性が要求される。 Anod: 2H 2 → 4H + + 4e −
Cathode: O 2 + 4H + + 4e − → 2H 2 O
Both the anode and the cathode of the solid polymer fuel cell are composed of a gas diffusion layer and a catalyst layer, and the catalyst layer is joined to the solid polymer electrolyte membrane. The catalyst layer contains a platinum group metal catalyst, and the electrochemical reaction proceeds in this catalyst layer. The gas diffusion layer in contact with the catalyst layer has functions of supplying a reaction gas to the catalyst layer and collecting current. Furthermore, water produced by the reaction on the cathode side is discharged through the gas diffusion layer. Therefore, the gas diffusion layer is required to have gas permeability, conductivity, and water repellency. The catalyst layer is also required to have water repellency so that water as a reaction product does not stay.

固体高分子形燃料電池の電極の触媒金属として、カソードには白金を用いることが知られている。触媒金属としての白金を超少量担持する触媒粉末の製作方法が特許文献１および特許文献２で開示されている。この触媒粉末の具体的な製造方法はつぎのとおりである。まず、陽イオン交換樹脂溶液とカーボンとを混合し、吸引濾過し、乾燥して、カーボン粒子表面を陽イオン交換樹脂で被覆する。つぎに、このカーボンを白金錯体陽イオンを含む水溶液中に浸漬し、イオン交換反応により、白金錯体の陽イオンを陽イオン交換樹脂のプロトン伝導経路に吸着させる。さらに、プロトン伝導経路に吸着した白金錯体の陽イオンを１８０℃の水素雰囲気中で還元して、触媒金属とする。   It is known that platinum is used for a cathode as a catalyst metal of an electrode of a polymer electrolyte fuel cell. Patent Document 1 and Patent Document 2 disclose a method for producing a catalyst powder carrying a very small amount of platinum as a catalyst metal. A specific method for producing the catalyst powder is as follows. First, a cation exchange resin solution and carbon are mixed, suction filtered, and dried to coat the surface of carbon particles with a cation exchange resin. Next, the carbon is immersed in an aqueous solution containing a platinum complex cation, and the cation of the platinum complex is adsorbed on the proton conduction path of the cation exchange resin by an ion exchange reaction. Furthermore, the cation of the platinum complex adsorbed on the proton conduction path is reduced in a hydrogen atmosphere at 180 ° C. to form a catalyst metal.

この方法により製作した触媒粉末は、触媒金属が陽イオン交換樹脂のプロトン伝導経路とカーボンの表面との接面に主に担持しているので、この触媒粉末を含む電極を備えるＰＥＦＣは、超少量の触媒金属担持量で優れた分極特性を示す。   In the catalyst powder produced by this method, the catalyst metal is mainly supported on the contact surface between the proton conduction path of the cation exchange resin and the carbon surface. Therefore, the PEFC including the electrode containing the catalyst powder is very small in quantity. It exhibits excellent polarization characteristics at a catalytic metal loading of.

この超少量金属担持触媒の製作方法としては、炭素質材料と陽イオン交換樹脂の溶液との混合物を噴霧乾燥する方法が特許文献２で開示されている。また、特許文献３では、電極触媒粉末の製造方法に噴霧乾燥法を用いることが開示されており、複合体粒子、カーボン、疎水性ポリマー、プロトン伝達ポリマーなどを含む電極触媒を噴霧乾燥法で生成することが記載されている。   As a method for producing this ultra-small amount metal-supported catalyst, Patent Document 2 discloses a method of spray-drying a mixture of a carbonaceous material and a cation exchange resin solution. Patent Document 3 discloses that a spray drying method is used as a method for producing an electrode catalyst powder, and an electrode catalyst containing composite particles, carbon, a hydrophobic polymer, a proton transfer polymer, and the like is generated by a spray drying method. It is described to do.

特開２０００−１７３６２６号公報JP 2000-173626 A 特開２００３−２５７４３９号公報JP 2003-257439 A 特表２００４−５０７３４１号公報JP-T-2004-507341

上記の特許文献１や特許文献２で開示された方法によって作製した超少量金属担持触媒では、陽イオン交換樹脂のカーボン粒子表面での分布が不均一であるため、この触媒混合体を含むＰＥＦＣ用電極のプロトン伝導度は低い。したがって、この触媒混合体を含むＰＥＦＣ用電極を備えるＰＥＦＣの初期性能は低いという問題があった。   In the ultra-small amount metal-supported catalyst prepared by the methods disclosed in Patent Document 1 and Patent Document 2 above, the distribution of the cation exchange resin on the surface of the carbon particles is non-uniform. The proton conductivity of the electrode is low. Therefore, there was a problem that the initial performance of PEFC provided with the electrode for PEFC containing this catalyst mixture was low.

ＰＥＦＣの初期性能を向上させるためには、カーボン粒子表面の陽イオン交換樹脂の分布をできるだけ均一にすることによって、触媒混合体の伝導度を高める必要がある。   In order to improve the initial performance of PEFC, it is necessary to increase the conductivity of the catalyst mixture by making the distribution of the cation exchange resin on the surface of the carbon particles as uniform as possible.

一方、特許文献２では、噴霧乾燥法については「炭素質材料と陽イオン交換樹脂の溶液との混合物を噴霧乾燥する」と記載されているだけで、噴霧乾燥法の詳しい条件等については記載されていない。   On the other hand, in Patent Document 2, the spray drying method is merely described as “spray drying a mixture of a carbonaceous material and a cation exchange resin solution”, and detailed conditions of the spray drying method are described. Not.

さらに、特許文献３に記載の複合電極触媒粉末の製造方法は、担体相（カーボン）の前駆体であるコロイド状カーボンと、Ｐｔ触媒活性種の前駆体であるＰｔ（ＮＨ３）４（ＮＯ３）２とを含む液体前駆体を、噴霧処理し、霧化して小滴とし、この小滴から液体を除去して粉末を生成する方法である。この製造法では、前駆体の乾燥および触媒的活性種への変換は１つの工程で都合よく併せて行われ、溶媒の除去と前駆体の活性種への変換とは本質的に同時に起こることが特徴であるため、この製造方法を、特許文献１や特許文献２に記載された超少量金属担持触媒の製造方法に適用することはできない。 Furthermore, the method for producing a composite electrode catalyst powder described in Patent Document 3 includes colloidal carbon that is a precursor of a carrier phase (carbon) and Pt (NH 3 ) 4 (NO 3 ) that is a precursor of a Pt catalytically active species. 2 ) A liquid precursor containing 2 is sprayed, atomized into droplets, and the liquid is removed from the droplets to produce a powder. In this production process, the drying of the precursor and the conversion to the catalytically active species are conveniently combined in one step, and the removal of the solvent and the conversion of the precursor to the active species can occur essentially simultaneously. Since it is a characteristic, this manufacturing method cannot be applied to the manufacturing method of the ultra-small amount metal supported catalyst described in Patent Document 1 and Patent Document 2.

そこで、本発明の目的は、超少量金属担持触媒の製造方法において、カーボン粒子表面の陽イオン交換樹脂の分布を、できるだけ均一におこなうことが可能な製造方法を提供し、この製造方法で得られた触媒混合体を用いることにより、初期性能が飛躍的に改善された固体高分子形燃料電池（ＰＥＦＣ）を提供することにある。   Accordingly, an object of the present invention is to provide a production method capable of performing the distribution of the cation exchange resin on the surface of the carbon particles as uniformly as possible in the production method of the ultra-small amount metal-supported catalyst, and obtained by this production method. Another object of the present invention is to provide a polymer electrolyte fuel cell (PEFC) whose initial performance is remarkably improved by using the catalyst mixture.

請求項１の発明は、固体高分子形燃料電池用触媒混合体の製造方法において、カーボンと陽イオン交換樹脂溶液との混合物を噴霧乾燥して、カーボンと陽イオン交換樹脂との混合物Ｘを得る第１の工程と、前記混合物Ｘ中の陽イオン交換樹脂の固定イオンに触媒金属元素の陽イオンを吸着させる第２の工程と、前記触媒金属元素の陽イオンを化学的に還元して混合物Ｙを得る第３の工程と、前記混合物Ｙと陽イオン交換樹脂溶液との混合物を噴霧乾燥する第４の工程とを経ることを特徴とする。   The invention of claim 1 is a method for producing a catalyst mixture for a polymer electrolyte fuel cell, wherein a mixture of carbon and a cation exchange resin solution is spray-dried to obtain a mixture X of carbon and a cation exchange resin. A first step, a second step of adsorbing a cation of the catalytic metal element to a fixed ion of the cation exchange resin in the mixture X, and a mixture Y by chemically reducing the cation of the catalytic metal element And a fourth step of spray-drying the mixture of the mixture Y and the cation exchange resin solution.

請求項２の発明は、請求項１記載の固体高分子形燃料電池用触媒混合体の製造方法において、第４の工程における混合物Ｙ中の陽イオン交換樹脂に対する陽イオン交換樹脂溶液中の陽イオン交換樹脂の割合が、５質量％以上、２５質量％以下であることを特徴とする。   The invention of claim 2 is the method for producing a catalyst mixture for a polymer electrolyte fuel cell according to claim 1, wherein the cation in the cation exchange resin solution with respect to the cation exchange resin in the mixture Y in the fourth step. The ratio of the exchange resin is 5% by mass or more and 25% by mass or less.

請求項３の発明は、請求項１または２記載の固体高分子形燃料電池用触媒混合体の製造方法において、第４の工程における噴霧乾燥温度が１００℃以上、１５０℃以下であることを特徴とする。   The invention of claim 3 is the method for producing a catalyst mixture for a polymer electrolyte fuel cell according to claim 1 or 2, wherein the spray drying temperature in the fourth step is 100 ° C or higher and 150 ° C or lower. And

請求項４の発明は、固体高分子形燃料電池において、上記の製造方法により製造された固体高分子形燃料電池用触媒混合体を備えることを特徴とする。   According to a fourth aspect of the present invention, in the polymer electrolyte fuel cell, the catalyst mixture for the polymer electrolyte fuel cell produced by the production method described above is provided.

本発明の固体高分子形燃料電池用触媒混合体の製造方法によれば、まず、第１の工程〜第３の工程により、混合物Ｙを作製し、第４の工程で、この混合物Ｙと陽イオン交換樹脂溶液との混合物を噴霧乾燥することによって、カーボン粒子表面の陽イオン交換樹脂の分布を均一にすることができるため、得られた触媒混合体を含む固体高分子形燃料電池用電極のプロトン伝導度が著しく向上し、その結果、この電極を備えるＰＥＦＣの初期性能が飛躍的に向上するものである。   According to the method for producing a catalyst mixture for a polymer electrolyte fuel cell of the present invention, first, the mixture Y is produced by the first to third steps, and the mixture Y and the positive mixture are obtained in the fourth step. By spray-drying the mixture with the ion exchange resin solution, the distribution of the cation exchange resin on the surface of the carbon particles can be made uniform. Therefore, the electrode of the polymer electrolyte fuel cell electrode containing the obtained catalyst mixture can be obtained. The proton conductivity is remarkably improved, and as a result, the initial performance of the PEFC equipped with this electrode is dramatically improved.

本発明の固体高分子形燃料電池用触媒混合体の製造方法は、つぎの４つの工程を経るところに特徴がある。   The method for producing a catalyst mixture for a polymer electrolyte fuel cell according to the present invention is characterized by the following four steps.

第１の工程では、カーボンと陽イオン交換樹脂溶液との混合物を噴霧乾燥して、カーボンと陽イオン交換樹脂との混合物Ｘを得る。混合物Ｘにおいては、カーボン粒子表面は陽イオン交換樹脂で被覆されている。   In the first step, a mixture of carbon and cation exchange resin solution is spray-dried to obtain a mixture X of carbon and cation exchange resin. In the mixture X, the carbon particle surfaces are coated with a cation exchange resin.

第２の工程では、イオン交換反応により、前記混合物Ｘ中の陽イオン交換樹脂の固定イオンに触媒金属元素の陽イオンを吸着させる。   In the second step, the cation of the catalytic metal element is adsorbed on the fixed ions of the cation exchange resin in the mixture X by an ion exchange reaction.

第３の工程では、前記触媒金属元素の陽イオンを化学的に還元して混合物Ｙを得る。   In the third step, a mixture Y is obtained by chemically reducing the cation of the catalytic metal element.

第４の工程では、前記混合物Ｙと陽イオン交換樹脂溶液との混合物を噴霧乾燥することにより、触媒混合体を得る。   In the fourth step, a catalyst mixture is obtained by spray drying the mixture of the mixture Y and the cation exchange resin solution.

本発明においては、第４の工程で、混合物Ｙと陽イオン交換樹脂溶液との混合物を噴霧乾燥することにより、カーボン粒子表面の陽イオン交換樹脂の分布を均一にすることができる。   In the present invention, the distribution of the cation exchange resin on the surface of the carbon particles can be made uniform by spray drying the mixture of the mixture Y and the cation exchange resin solution in the fourth step.

第４の工程において、混合物Ｙと陽イオン交換樹脂溶液との混合は減圧雰囲気下で行うことが好ましい。その理由は、混合物Ｙが減圧雰囲気下の混合により微粒化するので、得られた触媒混合体の電子伝導度が向上するからである。   In the fourth step, the mixture Y and the cation exchange resin solution are preferably mixed in a reduced-pressure atmosphere. The reason is that since the mixture Y is atomized by mixing in a reduced-pressure atmosphere, the electron conductivity of the obtained catalyst mixture is improved.

第４の工程における噴霧乾燥温度は、溶媒を充分に揮発させるため１００℃以上であることが好ましく、陽イオン交換樹脂の熱による収縮および分解の抑制のため１５０℃以下であることが好ましい。   The spray drying temperature in the fourth step is preferably 100 ° C. or higher in order to sufficiently volatilize the solvent, and is preferably 150 ° C. or lower in order to suppress shrinkage and decomposition due to heat of the cation exchange resin.

第４の工程において、混合物Ｙと混合する陽イオン交換樹脂の割合は、その樹脂でカーボンを均一に被覆できるので、触媒粒子中の樹脂の質量に対して５質量％以上であることが好ましく、その触媒を備える電極の電子伝導性の低下が抑制できるので、２５質量％以下であることが好ましい。   In the fourth step, the ratio of the cation exchange resin mixed with the mixture Y is preferably 5% by mass or more based on the mass of the resin in the catalyst particles, since the carbon can be uniformly coated with the resin. Since the fall of the electronic conductivity of the electrode provided with the catalyst can be suppressed, it is preferable that it is 25 mass% or less.

本発明においては、第４の工程で用いる陽イオン交換樹脂溶液の濃度や、カーボンと陽イオン交換樹脂との混合比にもよるが、第４の工程を２回以上繰り返すことによって、カーボン粒子表面の陽イオン交換樹脂の分布をより均一にすることができる。   In the present invention, depending on the concentration of the cation exchange resin solution used in the fourth step and the mixing ratio of carbon and cation exchange resin, the surface of the carbon particles can be obtained by repeating the fourth step twice or more. The distribution of the cation exchange resin can be made more uniform.

本発明の第３の工程で得られた混合物Ｙに含まれる触媒金属は、カーボンの表面と陽イオン交換樹脂のプロトン伝導経路との接面に主に担持されている。したがって、第４の工程で得られる触媒混合体に含まれる触媒金属は、混合物Ｙと同様に、カーボンの表面と陽イオン交換樹脂のプロトン伝導経路との接面に主に担持されている。   The catalytic metal contained in the mixture Y obtained in the third step of the present invention is mainly supported on the contact surface between the carbon surface and the proton conduction path of the cation exchange resin. Therefore, like the mixture Y, the catalyst metal contained in the catalyst mixture obtained in the fourth step is mainly supported on the contact surface between the carbon surface and the proton conduction path of the cation exchange resin.

カーボン粒子の表面と陽イオン交換樹脂のプロトン伝導経路との接面は、電子とプロトンとの授受を同時におこなうことのできる場所であるので、この接面に担持された触媒金属は電極反応に効率的に関与する。したがって、この接面に担持された触媒金属の割合を高めることによって、触媒金属の使用量を低減できる。   The contact surface between the surface of the carbon particle and the proton conduction path of the cation exchange resin is a place where electrons and protons can be exchanged at the same time. Therefore, the catalytic metal supported on this contact surface is efficient for the electrode reaction. Involved. Therefore, the amount of catalyst metal used can be reduced by increasing the ratio of the catalyst metal supported on the contact surface.

本発明の固体高分子形燃料電池用触媒混合体において、「触媒金属が陽イオン交換樹脂のプロトン伝導経路とカーボン粒子表面との接面に主として備えられている」とは、陽イオン交換樹脂のプロトン伝導経路に接するカーボン粒子表面に担持された触媒金属量が全触媒金属担持量の５０質量％以上であることを意味する。すなわち、全触媒金属担持量の５０質量％以上が、電極反応に対して活性な触媒金属であるため、触媒金属の利用率が著しく高くなる。   In the catalyst mixture for a polymer electrolyte fuel cell of the present invention, “the catalytic metal is mainly provided on the contact surface between the proton conduction path of the cation exchange resin and the carbon particle surface” means that the cation exchange resin It means that the amount of catalyst metal supported on the surface of carbon particles in contact with the proton conduction path is 50% by mass or more of the total amount of catalyst metal supported. That is, 50% by mass or more of the total catalytic metal loading is a catalytic metal active for the electrode reaction, so that the utilization rate of the catalytic metal is remarkably increased.

なお、本発明においては、陽イオン交換樹脂のプロトン伝導経路に接するカーボン粒子表面に担持された触媒金属量の全触媒金属担持量に対する割合は高いほど好ましく、特に８０質量％を超えていることが好ましい。このようにして、プロトン伝導経路とカーボン粒子との接触面に触媒金属を高率で担持させることによって、電極の高活性化がはかられる。   In the present invention, the ratio of the amount of the catalyst metal supported on the surface of the carbon particles in contact with the proton conduction path of the cation exchange resin to the total amount of the catalyst metal supported is preferably as high as possible, particularly exceeding 80% by mass. preferable. In this way, the electrode is highly activated by supporting the catalytic metal at a high rate on the contact surface between the proton conduction path and the carbon particles.

本発明の触媒混合体において「触媒金属が陽イオン交換樹脂のプロトン伝導経路とカーボン粒子表面との接面に主として備えられている」ことは、この触媒混合体を備えた燃料電池の高電流密度領域における質量活性と、陽イオン交換樹脂のプロトン伝導経路と疎水性骨格との体積比とからわかる（Ｍ．Ｋｏｈｍｏｔｏ ｅｔ．ａｌ．，ＧＳ Ｙｕａｓａ Ｔｅｃｈｎｉｃａｌ Ｒｅｐｏｒｔ，１，４８（２００４））。この質量活性とは、ある電圧における電流密度を、単位面積あたりの触媒金属担持量で除したものである。   In the catalyst mixture of the present invention, “the catalyst metal is mainly provided on the contact surface between the proton conduction path of the cation exchange resin and the carbon particle surface” means that the high current density of the fuel cell provided with this catalyst mixture is high. It can be seen from the mass activity in the region and the volume ratio between the proton conduction pathway of the cation exchange resin and the hydrophobic skeleton (M. Komomoto et.al., GS Yuasa Technical Report, 1, 48 (2004)). This mass activity is obtained by dividing the current density at a certain voltage by the amount of catalyst metal supported per unit area.

本発明で用いる陽イオン交換樹脂は、プロトン伝導性を示せばどのようなものでも良いが、化学的に安定で耐試薬特性に優れたパーフルオロカーボンスルフォン酸系のものが好ましい。   The cation exchange resin used in the present invention may be any cation exchange resin as long as it exhibits proton conductivity, but is preferably a perfluorocarbon sulfonic acid type that is chemically stable and excellent in reagent resistance.

本発明で用いるカーボンは、特に限定されるものではないが、ファーネスブラック、アセチレンブラック、ランプブラック、サーマルブラック、チャンネルブラックなどのカーボンブラックを用いることができる。これらの中では、触媒金属の陽イオンを含む化合物の還元に対して高い活性を示すものが好ましく、例えば、デンカブラック、バルカンＸＣ−７２、ケッチェンブラックＥＣ、ブラックパール２０００等のカーボンブラックが好ましい。   The carbon used in the present invention is not particularly limited, and carbon black such as furnace black, acetylene black, lamp black, thermal black, channel black, and the like can be used. Among these, those showing high activity for the reduction of the compound containing a catalytic metal cation are preferable, and for example, carbon black such as Denka Black, Vulcan XC-72, Ketjen Black EC, Black Pearl 2000 and the like are preferable. .

本発明で用いる触媒金属元素の陽イオンは、酸素の還元反応対して高い活性を示す、白金、ロジウム、ルテニウム、イリジウム、パラジウム、オスニウムなどの白金族金属のものが好ましい。   The cation of the catalytic metal element used in the present invention is preferably a platinum group metal such as platinum, rhodium, ruthenium, iridium, palladium, osnium and the like, which exhibits high activity for the oxygen reduction reaction.

本発明では、吸着した陽イオンの還元には、水素ガス、水素を含むガスまたはヒドラジンを含む不活性ガスによって気相還元する方法が好ましい。ここで、水素を含むガスとしたは、水素ガスと窒素、水素とヘリウムまたはアルゴンなどの不活性ガスとの混合ガスを用いることができる。   In the present invention, it is preferable to reduce the adsorbed cation by a gas phase reduction method using hydrogen gas, a gas containing hydrogen, or an inert gas containing hydrazine. Here, as the gas containing hydrogen, a mixed gas of hydrogen gas and nitrogen, hydrogen and an inert gas such as helium or argon can be used.

本発明では、第１の工程〜第４の工程で得られた触媒混合体を用い、この触媒混合体と撥水性樹脂とをＮ−メチル−２−ピロリドン（ＮＭＰ）等の溶媒に分散させ、この分散物をスプレーまたはアプリケータにより基材上に塗布し、乾燥することによって、触媒混合体を備える固体高分子形燃料電池用電極を製作することができる。   In the present invention, using the catalyst mixture obtained in the first to fourth steps, the catalyst mixture and the water repellent resin are dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP), The dispersion is applied onto a substrate by spraying or an applicator, and dried to produce a polymer electrolyte fuel cell electrode having a catalyst mixture.

本発明において、ＮＭＰ等の溶媒に触媒混合体とともに分散させる撥水性樹脂には、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体（ＦＥＰ）、ポリテトラフルオロエチレン（ＰＴＦＥ）またはポリビニリデンフルオライド（ＰＶＤＦ）が高撥水性であるので好ましい。   In the present invention, the water-repellent resin dispersed together with the catalyst mixture in a solvent such as NMP includes tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polytetrafluoroethylene (PTFE), or polyvinylidene fluoride (PVDF). Is preferable because of its high water repellency.

さらに、本発明では、この固体高分子形燃料電池用電極に空孔を形成することによって、カソードの酸素還元反応によって生成する水を電極から円滑に排出することができる。電極に空孔を形成する方法は、例えば、触媒混合体および撥水性樹脂をＮＭＰ等の溶媒に分散させ、この分散液に造孔剤を加えてペーストとし、このペーストをシート上に塗布、乾燥し、その後、造孔剤を溶出させる方法によっておこなうことができる。造孔剤は限定されるものではなく、炭酸カルシウム、ニッケル粉末および塩化ナトリウム等がある。   Furthermore, in the present invention, water generated by the oxygen reduction reaction of the cathode can be smoothly discharged from the electrode by forming pores in the polymer electrolyte fuel cell electrode. The method of forming pores in the electrode is, for example, by dispersing the catalyst mixture and water-repellent resin in a solvent such as NMP, adding a pore-forming agent to this dispersion to form a paste, and applying this paste on a sheet and drying Then, it can be performed by a method of eluting the pore-forming agent. The pore-forming agent is not limited and includes calcium carbonate, nickel powder, sodium chloride and the like.

以下、本発明を好適な実施例を用いて説明する。   The present invention will be described below with reference to preferred embodiments.

［実施例１〜４および比較例１、２］
［実施例１］
第１の工程では、陽イオン交換樹脂溶液（Ｎａｆｉｏｎ、５質量％溶液、Ａｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌ製）４０ｇ、カーボン（Ｖｕｌｃａｎ ＸＣ−７２、Ｃａｂｏｔ製）３ｇおよびイソプロパノール（ナカライテスク製）７７ｇを真空ミキサーを用いて回転速度４０００ｒ．ｐ．ｍ．、攪拌時間１０分、４００Ｔｏｒｒの減圧雰囲気の条件で混合し、その混合物を噴霧乾燥機を用いて乾燥温度１２０℃の条件で造粒することによって、カーボン粒子表面を陽イオン交換樹脂で被覆した混合物Ｘを作製した。混合物Ｘにおいては、カーボンと陽イオン交換樹脂との質量割合は６０：４０であった。 [Examples 1 to 4 and Comparative Examples 1 and 2]
[Example 1]
In the first step, 40 g of a cation exchange resin solution (Nafion, 5% by mass solution, manufactured by Aldrich Chemical), 3 g of carbon (Vulcan XC-72, manufactured by Cabot) and 77 g of isopropanol (manufactured by Nacalai Tesque) were used using a vacuum mixer. Rotational speed 4000 r. p. m. Mixing is carried out under a reduced pressure atmosphere condition of 400 Torr with a stirring time of 10 minutes, and the mixture is granulated at a drying temperature of 120 ° C. using a spray dryer, whereby the carbon particle surface is coated with a cation exchange resin. X was produced. In mixture X, the mass ratio of carbon to cation exchange resin was 60:40.

つづいて、第２の工程では、混合物Ｘ４ｇを０．０５ｍｏｌ／ｌの濃度の［Ｐｔ（ＮＨ３）４］Ｃｌ２水溶液３０５ｍｌに２４時間浸漬し、陽イオン交換樹脂に［Ｐｔ（ＮＨ３）４］２＋イオンを吸着させ、精製水で充分洗浄・乾燥し、第３の工程では、水素雰囲気中で１８０℃、６時間還元して、混合物Ｙを作製した。 Subsequently, in the second step, 4 g of the mixture X was immersed in 305 ml of [Pt (NH 3 ) 4 ] Cl 2 aqueous solution having a concentration of 0.05 mol / l for 24 hours, and [Pt (NH 3 ) 4 was added to the cation exchange resin. 2+ ions were adsorbed, thoroughly washed and dried with purified water, and in the third step, the mixture Y was reduced in a hydrogen atmosphere at 180 ° C. for 6 hours to prepare a mixture Y.

つぎに、第４の工程では、混合物Ｙ３ｇ、陽イオン交換樹脂溶液（Ｎａｆｉｏｎ５質量％溶液、ＡｌｄｒｉｃｈＣｈｅｍｉｃａｌ製）２．５６ｇおよびイソプロパノール（ナカライテスク製）７７ｇを、真空ミキサーを用いて回転速度４０００ｒ．ｐ．ｍ．、攪拌時間１０分、４００Ｔｏｒｒの減圧雰囲気の条件で混合し、この混合物を噴霧乾燥機を用いて乾燥温度１２０℃の条件で造粒することによって、実施例１の固体高分子形燃料電池用触媒混合体Ａを製作した。   Next, in the fourth step, 3 g of the mixture Y, 2.56 g of a cation exchange resin solution (Nafion 5 mass% solution, manufactured by Aldrich Chemical) and 77 g of isopropanol (manufactured by Nacalai Tesque) were mixed at a rotational speed of 4000 r. p. m. The catalyst for the polymer electrolyte fuel cell of Example 1 was prepared by mixing under a reduced pressure atmosphere condition of 400 Torr with a stirring time of 10 minutes and granulating the mixture at a drying temperature of 120 ° C. using a spray dryer. Mixture A was made.

混合物Ｙと混合した陽イオン交換樹脂（２．５６ｇ×０．０５＝０．１２８ｇ）の割合は、混合物Ｙ中の陽イオン交換樹脂（３ｇ×０．４＝１．２ｇ）に対して１０．７質量％であり、触媒混合体Ａにおけるカーボン（１．８ｇ）と陽イオン交換樹脂（１．２＋０．１２８ｇ）との割合は５７．５：４２．５であった。   The ratio of the cation exchange resin (2.56 g × 0.05 = 0.128 g) mixed with the mixture Y was 10. with respect to the cation exchange resin (3 g × 0.4 = 1.2 g) in the mixture Y. The ratio of carbon (1.8 g) to cation exchange resin (1.2 + 0.128 g) in the catalyst mixture A was 57.5: 42.5.

さらに、触媒混合体Ａ３ｇ、Ｎ−メチル−２−ピロリドン（三菱化学製）２７ｇ、ＦＥＰ分散液（ＦＥＰ１２０−Ｊ、５５質量％溶液、ＤｕＰｏｎｔ製）０．９１ｇおよび炭酸カルシウム（ＮＳ＃２００、日東粉化工業製）２．４０ｇを混合してペーストとし、この混合ペーストを金属シート上に塗布・乾燥して、カソード用電極を金属シート上に形成した。ＦＥＰの添加割合は、電極中のカーボンの質量に対して３０質量％であり、電極の白金担持量は０．０６ｍｇ／ｃｍ２であった。 Further, 3 g of the catalyst mixture A, 27 g of N-methyl-2-pyrrolidone (Mitsubishi Chemical), 0.91 g of FEP dispersion (FEP120-J, 55 mass% solution, DuPont) and calcium carbonate (NS # 200, Nitto flour) 2.40 g (manufactured by Kagaku Kogyo Co., Ltd.) was mixed to obtain a paste, and this mixed paste was applied onto a metal sheet and dried to form a cathode electrode on the metal sheet. The addition ratio of FEP was 30% by mass with respect to the mass of carbon in the electrode, and the amount of platinum supported on the electrode was 0.06 mg / cm 2 .

金属シートから剥離したカソード用電極と、０．６ｍｇ／ｃｍ２の触媒担持量の白金−ルテニウム担持カーボン（Ｐｔ：１９．６質量％、Ｒｕ：１５．２質量％、ＴＥＣ６１Ｖ３３、田中貴金属工業製）を備えるアノード用の電極とを、陽イオン交換膜（Ｎａｆｉｏｎ１１５、ＤｕＰｏｎｔ製）の両側に１０ＭＰａ、１３５℃の条件で接合して、膜／電極接合体（ＭＥＡ）を製作し、このＭＥＡを８０℃、０．５ｍｏｌ／ｌの硝酸水溶液に浸漬して、カソード用の電極に含まれる炭酸カルシウムを溶出させ、カーボンペーパーを両方の電極の外側に接合した。 Cathode electrode peeled from metal sheet and platinum-ruthenium-supported carbon with a catalyst loading of 0.6 mg / cm 2 (Pt: 19.6 mass%, Ru: 15.2 mass%, TEC61V33, manufactured by Tanaka Kikinzoku Kogyo) Are bonded to both sides of a cation exchange membrane (Nafion 115, manufactured by DuPont) under conditions of 10 MPa and 135 ° C. to produce a membrane / electrode assembly (MEA). Then, it was immersed in an aqueous solution of 0.5 mol / l nitric acid to elute calcium carbonate contained in the cathode electrode, and carbon paper was bonded to the outside of both electrodes.

最後に、このＭＥＡの電極部分の外側にガス流路の確保のためにガスフロープレートを配置し、これらをステンレス製のエンドプレートにより１２．７ＭＰａの圧力で圧迫して、実施例１の単セルＡを製作した。単セルＡにおけるカソード用電極の空孔率は７０％であった。   Finally, a gas flow plate is disposed outside the electrode portion of the MEA in order to secure a gas flow path, and these are pressed with a stainless steel end plate at a pressure of 12.7 MPa, whereby the single cell of Example 1 is used. A was made. The porosity of the cathode electrode in the single cell A was 70%.

［実施例２］
第４の工程において、混合物Ｙ３ｇとＮａｆｉｏｎ５質量％溶液１．２ｇとを混合し、
混合物Ｙと混合する陽イオン交換樹脂の割合を、混合物Ｙ中の陽イオン交換樹脂に対して５質量％としたことを除いては、実施例１と同様の方法によって、実施例２の固体高分子形燃料電池用触媒混合体Ｂおよび単セルＢを作製した。 [Example 2]
In the fourth step, 3 g of the mixture Y and 1.2 g of 5% Nafion solution are mixed,
Except that the ratio of the cation exchange resin to be mixed with the mixture Y was 5% by mass with respect to the cation exchange resin in the mixture Y, the solid content of Example 2 was obtained in the same manner as in Example 1. A catalyst mixture B and a single cell B for a molecular fuel cell were produced.

［実施例３］
第４の工程において、混合物Ｙ３ｇとＮａｆｉｏｎ５質量％溶液４．８ｇとを混合し、
混合物Ｙと混合する陽イオン交換樹脂の割合を、混合物Ｙ中の陽イオン交換樹脂に対して２０質量％としたことを除いては、実施例１と同様の方法によって、実施例３の固体高分子形燃料電池用触媒混合体Ｃおよび単セルＣを作製した。 [Example 3]
In the fourth step, 3 g of the mixture Y and 4.8 g of 5% Nafion solution are mixed,
Except that the ratio of the cation exchange resin to be mixed with the mixture Y was 20% by mass with respect to the cation exchange resin in the mixture Y, the solid content of Example 3 was obtained in the same manner as in Example 1. A catalyst mixture C and a single cell C for a molecular fuel cell were produced.

［実施例４］
第４の工程において、混合物Ｙ３ｇとＮａｆｉｏｎ５質量％溶液６．０ｇとを混合し、
混合物Ｙと混合する陽イオン交換樹脂の割合を、混合物Ｙ中の陽イオン交換樹脂に対して２５質量％としたことを除いては、実施例１と同様の方法によって、実施例４の固体高分子形燃料電池用触媒混合体Ｄおよび単セルＤを作製した。 [Example 4]
In the fourth step, 3 g of the mixture Y and 6.0 g of 5% Nafion solution are mixed,
Except that the ratio of the cation exchange resin to be mixed with the mixture Y was 25% by mass with respect to the cation exchange resin in the mixture Y, the solid content of Example 4 was obtained in the same manner as in Example 1. A catalyst mixture D and a single cell D for a molecular fuel cell were produced.

［比較例１］
第１の工程〜第３の工程は実施例１と同様にして混合物Ｙを作製した。混合物Ｙにおいては、カーボンと陽イオン交換樹脂との質量割合は６０：４０であった。 [Comparative Example 1]
The first to third steps were performed in the same manner as in Example 1 to prepare the mixture Y. In mixture Y, the mass ratio of carbon to cation exchange resin was 60:40.

つぎに、混合物Ｙ３ｇ、Ｎ−メチル−２−ピロリドン（三菱化学製）２７ｇ、ＦＥＰ分散液（ＦＥＰ１２０−Ｊ、５５質量％溶液、ＤｕＰｏｎｔ製）０．９５ｇおよび炭酸カルシウム（ＮＳ＃２００、日東粉化工業）２．３７ｇを混合してペーストとし、この混合ペーストを金属シート上に塗布・乾燥して、カソード用電極を金属シート上に形成した。ＦＥＰの添加割合は、電極中のカーボンの質量に対して３０質量％であり、電極の白金担持量は０．０６ｍｇ／ｃｍ２であった。 Next, 3 g of the mixture Y, 27 g of N-methyl-2-pyrrolidone (Mitsubishi Chemical), 0.95 g of FEP dispersion (FEP120-J, 55 mass% solution, DuPont), and calcium carbonate (NS # 200, Nitto Powder) (Industry) 2.37 g was mixed to obtain a paste, and this mixed paste was applied onto a metal sheet and dried to form a cathode electrode on the metal sheet. The addition ratio of FEP was 30% by mass with respect to the mass of carbon in the electrode, and the amount of platinum supported on the electrode was 0.06 mg / cm 2 .

このカソード用電極を用いて、実施例１と同様にして、膜／電極接合体（ＭＥＡ）を作製し、このＭＥＡを用いて、実施例１と同様にして比較例１の単セルＥを製作した。単セルＥにおけるカソード用電極の空孔率は７０％であった。   Using this cathode electrode, a membrane / electrode assembly (MEA) was produced in the same manner as in Example 1, and using this MEA, a single cell E of Comparative Example 1 was produced in the same manner as in Example 1. did. The porosity of the cathode electrode in the single cell E was 70%.

［比較例２］
第４の工程において、混合物Ｙ３ｇとＮａｆｉｏｎ５質量％溶液７．２ｇとを混合し、
混合物Ｙと混合する陽イオン交換樹脂の割合を、混合物Ｙ中の陽イオン交換樹脂に対して３０質量％としたことを除いては、実施例１と同様の方法によって、比較例２の固体高分子形燃料電池用触媒混合体Ｆおよび単セルＦを作製した。 [Comparative Example 2]
In the fourth step, 3 g of the mixture Y and 7.2 g of 5% Nafion solution are mixed,
Except that the ratio of the cation exchange resin to be mixed with the mixture Y was 30% by mass with respect to the cation exchange resin in the mixture Y, the solid content of Comparative Example 2 was measured in the same manner as in Example 1. A catalyst mixture F and a single cell F for a molecular fuel cell were produced.

第４の工程における、混合物Ｙと混合する陽イオン交換樹脂の割合が単セルの分極特性におよぼす影響を調査するために、単セルＡ〜Ｆの０．７Ｖにおける電流密度の値を測定した。測定条件は、燃料に水素（ガス利用率８０％）、酸化剤に空気（ガス利用率４０％）を用い、セル温度７０℃とした。   In order to investigate the influence of the proportion of the cation exchange resin mixed with the mixture Y on the polarization characteristics of the single cell in the fourth step, the value of the current density at 0.7 V of the single cells A to F was measured. Measurement conditions were such that hydrogen (gas utilization factor 80%) was used as fuel, air (gas utilization factor 40%) was used as oxidant, and the cell temperature was 70 ° C.

測定結果から得られた、第４の工程における混合物Ｙと混合する陽イオン交換樹脂の割合と単セルの電流密度との関係を図１に示した。図１において、横軸は、混合物Ｙ中の陽イオン交換樹脂の質量に対する陽イオン交換樹脂溶液中の陽イオン交換樹脂の質量の割合（以下では「触媒混合体中の陽イオン交換樹脂割合（質量％）」とする）で示した。   The relationship between the ratio of the cation exchange resin mixed with the mixture Y in the fourth step and the current density of the single cell obtained from the measurement results is shown in FIG. In FIG. 1, the horizontal axis represents the ratio of the mass of the cation exchange resin in the cation exchange resin solution to the mass of the cation exchange resin in the mixture Y (hereinafter, “the ratio of the cation exchange resin in the catalyst mixture (mass %) ”).

図１から、これらの単セルの０．７Ｖにおける電流密度は、触媒混合体中の陽イオン交換樹脂割合が０質量％から５質量％にかけて急激に増加していることがわかる。この電流密度の増加は、第４の工程を経ることにより、カーボン粒子表面が陽イオン交換樹脂で均一に被覆されたため、この触媒混合体を備える固体高分子形燃料電池用電極のプロトン伝導度が向上したことに起因するものと推定される。   From FIG. 1, it can be seen that the current density at 0.7 V of these single cells increases rapidly from 0% by mass to 5% by mass of the cation exchange resin in the catalyst mixture. This increase in current density is because the surface of the carbon particles is uniformly coated with the cation exchange resin through the fourth step, so that the proton conductivity of the electrode for the polymer electrolyte fuel cell comprising this catalyst mixture is increased. It is presumed to be due to the improvement.

さらに、触媒混合体中の陽イオン交換樹脂割合が２５質量％を超えた比較例２の場合には、電流密度は急激に減少することがわかる。この電流密度の減少は、この触媒混合体を備える電極の電子伝導性が低下したことに起因するものと推定される。   Furthermore, in the case of Comparative Example 2 in which the ratio of the cation exchange resin in the catalyst mixture exceeds 25% by mass, it can be seen that the current density rapidly decreases. This decrease in current density is presumed to be due to a decrease in the electronic conductivity of the electrode comprising this catalyst mixture.

以上の結果から、単セルの出力は、触媒混合体中の陽イオン交換樹脂割合が５質量％以上、２５質量％以下である場合に最も高いことが明らかになった。   From the above results, it became clear that the output of the single cell is the highest when the proportion of the cation exchange resin in the catalyst mixture is 5% by mass or more and 25% by mass or less.

［実施例５、６および比較例３〜５］
［比較例３］
陽イオン交換樹脂溶液（Ｎａｆｉｏｎ、５質量％溶液、Ａｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌ製）４０ｇ、カーボン（Ｖｕｌｃａｎ ＸＣ−７２、Ｃａｂｏｔ製）２．７１ｇおよびイソプロパノール（ナカライテスク）７７ｇを真空ミキサーを用いて回転速度４０００ｒ．ｐ．ｍ．、攪拌時間１０分、４００Ｔｏｒｒの減圧雰囲気の条件で混合し、この混合物を噴霧乾燥機を用いて乾燥温度１２０℃の条件で造粒することによって、カーボン粒子表面を陽イオン交換樹脂で被覆した混合物Ｘを作製した。混合物Ｘにおいては、カーボンと陽イオン交換樹脂との質量割合は５７．５：４２．５であった。 [Examples 5 and 6 and Comparative Examples 3 to 5]
[Comparative Example 3]
40 g of cation exchange resin solution (Nafion, 5% by mass solution, manufactured by Aldrich Chemical), 2.71 g of carbon (Vulcan XC-72, manufactured by Cabot) and 77 g of isopropanol (Nacalai Tesque) were used at a rotation speed of 4000 r. p. m. Mixing was performed under conditions of a reduced pressure atmosphere of 400 Torr with a stirring time of 10 minutes, and the mixture was granulated at a drying temperature of 120 ° C. using a spray dryer, whereby the carbon particle surface was coated with a cation exchange resin. X was produced. In mixture X, the mass ratio of carbon to cation exchange resin was 57.5: 42.5.

つづいて、混合物Ｘ４ｇを０．０５ｍｏｌ／ｌの濃度の［Ｐｔ（ＮＨ３）４］Ｃｌ２水溶液３２４ｍｌに２４時間浸漬し、陽イオン交換樹脂に［Ｐｔ（ＮＨ３）４］２＋イオンを吸着させ、精製水で充分洗浄・乾燥し、水素雰囲気中で１８０℃、６時間還元して、比較例３の固体高分子形燃料電池用触媒混合体Ｇを製作した。 Subsequently, 4 g of the mixture X was immersed in 324 ml of an aqueous solution [Pt (NH 3 ) 4 ] Cl 2 having a concentration of 0.05 mol / l for 24 hours to adsorb [Pt (NH 3 ) 4 ] 2+ ions to the cation exchange resin. The polymer mixture was thoroughly washed and dried with purified water, and reduced in a hydrogen atmosphere at 180 ° C. for 6 hours to produce a catalyst mixture G for polymer electrolyte fuel cell of Comparative Example 3.

さらに、触媒混合体Ｇを用いて、実施例１と同様にしてカソード用電極を作製し、このカソード用電極と実施例１で用いたのと同じアノード用電極とを、実施例１と同様の条件で陽イオン交換膜に接合して、膜／電極接合体（ＭＥＡ）を製作した。さらに、このＭＥＡを用いて実施例１と同様にして、単セルＧを製作した。このカソード用電極の空孔率は７０％であった。   Further, using the catalyst mixture G, a cathode electrode was prepared in the same manner as in Example 1, and this cathode electrode and the same anode electrode as used in Example 1 were the same as in Example 1. A membrane / electrode assembly (MEA) was fabricated by bonding to a cation exchange membrane under conditions. Further, a single cell G was manufactured using this MEA in the same manner as in Example 1. The cathode electrode had a porosity of 70%.

実施例１の単セルＡおよび比較例３の単セルＧの電流−電圧特性を図２に示す。測定条件は、燃料に水素（ガス利用率８０％）、酸化剤に空気（ガス利用率４０％）を用い、セル温度７０℃とした。図２において、記号○は単セルＡの、記号△は単セルＧの電流−電圧特性を示す。図２から、単セルＡの特性は単セルＧの場合と比較して優れていることがわかる。   The current-voltage characteristics of the single cell A of Example 1 and the single cell G of Comparative Example 3 are shown in FIG. Measurement conditions were such that hydrogen (gas utilization factor 80%) was used as fuel, air (gas utilization factor 40%) was used as oxidant, and the cell temperature was 70 ° C. In FIG. 2, the symbol ◯ indicates the current-voltage characteristic of the single cell A, and the symbol Δ indicates the current-voltage characteristic of the single cell G. As can be seen from FIG. 2, the characteristics of the single cell A are superior to those of the single cell G.

このことは、実施例１では、第４の工程において、触媒金属が陽イオン交換樹脂のプロトン伝導経路とカーボンの表面との接面に主に担持している触媒混合物である混合物Ｙと陽イオン交換樹脂溶液との混合物を噴霧乾燥することにより、陽イオン交換樹脂のカーボンへの被覆が均一におこなわれるため、触媒混合体を備える電極のプロトン伝導度が高くなることに起因すると推定される。   This is because, in Example 1, in the fourth step, the catalyst Y is a catalyst mixture mainly supported on the contact surface between the proton conduction path of the cation exchange resin and the surface of the carbon, and the mixture Y and the cation. By spray-drying the mixture with the exchange resin solution, the carbon of the cation exchange resin is uniformly coated, so that it is estimated that the proton conductivity of the electrode including the catalyst mixture is increased.

［実施例５］
第４の工程における噴霧乾燥温度が１００℃であることを除いては、実施例１の場合と同様の方法によって、実施例５の固体高分子形燃料電池用触媒混合体Ｈおよび単セルＨを製作した。 [Example 5]
Except that the spray drying temperature in the fourth step is 100 ° C., the solid polymer fuel cell catalyst mixture H and the single cell H of Example 5 were obtained in the same manner as in Example 1. Produced.

［実施例６］
第４の工程における噴霧乾燥温度が１５０℃であることを除いては、実施例１の場合と同様の方法によって、実施例６の固体高分子形燃料電池用触媒混合体Ｉよび単セルＩを製作した。 [Example 6]
Except that the spray drying temperature in the fourth step is 150 ° C., the catalyst mixture I and the single cell I for the polymer electrolyte fuel cell of Example 6 were prepared in the same manner as in Example 1. Produced.

［比較例４］
第４の工程における噴霧乾燥温度が８０℃であることを除いては、実施例１の場合と同様の方法によって、比較例４の固体高分子形燃料電池用触媒混合体Ｊおよび単セルＪを製作した。 [Comparative Example 4]
Except that the spray drying temperature in the fourth step is 80 ° C., the solid polymer fuel cell catalyst mixture J and the single cell J of Comparative Example 4 were prepared in the same manner as in Example 1. Produced.

［比較例５］
第４の工程における噴霧乾燥温度が１８０℃であることを除いては、実施例１の場合と同様の方法によって、比較例５の固体高分子形燃料電池用触媒混合体Ｋおよび単セルＫを製作した。 [Comparative Example 5]
Except that the spray-drying temperature in the fourth step is 180 ° C., the solid polymer fuel cell catalyst mixture K and the single cell K of Comparative Example 5 were prepared in the same manner as in Example 1. Produced.

第４の工程における混合物Ｙと陽イオン交換樹脂溶液とイソプロパノールとの混合物の噴霧乾燥温度が単セルの分極特性におよぼす影響を調査するために、単セルＡおよびＨ〜Ｋの作動電圧０．７Ｖにおける電流密度の値を測定した。測定条件は、燃料に水素（ガス利用率８０％）、酸化剤に空気（ガス利用率４０％）を用い、セル温度７０℃とした。この測定から得られた噴霧乾燥温度と単セルの作動電圧０．７Ｖにおける電流密度との関係を図３に示す。   In order to investigate the influence of the spray drying temperature of the mixture of the mixture Y, the cation exchange resin solution and the isopropanol in the fourth step on the polarization characteristics of the single cells, the operating voltage of the single cells A and HK is 0.7V. The value of current density at was measured. Measurement conditions were such that hydrogen (gas utilization factor 80%) was used as fuel, air (gas utilization factor 40%) was used as oxidant, and the cell temperature was 70 ° C. The relationship between the spray drying temperature obtained from this measurement and the current density at an operating voltage of 0.7 V of the single cell is shown in FIG.

図３から、これらの単セルの０．７Ｖにおける電流密度は、噴霧乾燥温度が８０℃以上になると急激に増加し、１００〜１５０℃の間でほぼ一定になることがわかる。この電流密度の増加は、噴霧乾燥中に混合物中の溶媒が充分に揮発したので、微細な粒子が形成したことに起因すると推定される。   From FIG. 3, it can be seen that the current density at 0.7 V of these single cells increases rapidly when the spray drying temperature is 80 ° C. or higher, and is substantially constant between 100 and 150 ° C. This increase in current density is presumed to be due to the formation of fine particles because the solvent in the mixture was sufficiently volatilized during spray drying.

一方、噴霧乾燥温度が１５０℃を超えると、電流密度は急激に減少することがわかる。この電流密度の減少は、陽イオン交換樹脂の熱による収縮および分解によって、電極のプロトン伝導度が低下したことによるものと考えられる。これらのことから、単セルの出力は、第４の工程における噴霧乾燥温度が１００℃以上、１５０℃以下の場合に、最も高いことが明らかになった。   On the other hand, when the spray drying temperature exceeds 150 ° C., it can be seen that the current density rapidly decreases. This decrease in current density is thought to be due to a decrease in proton conductivity of the electrode due to heat shrinkage and decomposition of the cation exchange resin. From these, it became clear that the output of the single cell is the highest when the spray drying temperature in the fourth step is 100 ° C. or higher and 150 ° C. or lower.

第４の工程における、触媒混合体中の陽イオン交換樹脂割合と作動電圧０．７Ｖにおける単セルの電流密度との関係示す図。The figure which shows the relationship between the cation exchange resin ratio in a catalyst mixture in the 4th process, and the current density of the single cell in the operating voltage of 0.7V. 単セルＡおよび単セルＧの電流−電圧特性を示す図。The figure which shows the current-voltage characteristic of the single cell A and the single cell G. 単セルＡおよびＨ〜Ｋの、第４の工程の噴霧乾燥温度と作動電圧０．７Ｖにおける電流密度との関係を示す図。The figure which shows the relationship between the spray-drying temperature of the 4th process of the single cell A and HK and the current density in the operating voltage of 0.7V.

Claims (4)

カーボンと陽イオン交換樹脂溶液との混合物を噴霧乾燥して、カーボンと陽イオン交換樹脂との混合物Ｘを得る第１の工程と、前記混合物Ｘ中の陽イオン交換樹脂の固定イオンに触媒金属元素の陽イオンを吸着させる第２の工程と、前記触媒金属元素の陽イオンを化学的に還元して混合物Ｙを得る第３の工程と、前記混合物Ｙと陽イオン交換樹脂溶液との混合物を噴霧乾燥する第４の工程とを経ることを特徴とする固体高分子形燃料電池用触媒混合体の製造方法。 A first step of spray-drying a mixture of carbon and a cation exchange resin solution to obtain a mixture X of carbon and cation exchange resin; and a catalytic metal element as a fixed ion of the cation exchange resin in the mixture X A second step of adsorbing the cation of the catalyst, a third step of chemically reducing the cation of the catalytic metal element to obtain a mixture Y, and spraying a mixture of the mixture Y and a cation exchange resin solution A method for producing a catalyst mixture for a polymer electrolyte fuel cell, comprising: a fourth step of drying. 第４の工程において、混合物Ｙ中の陽イオン交換樹脂に対する陽イオン交換樹脂溶液中の陽イオン交換樹脂の割合が、５質量％以上、２５質量％以下であることを特徴とする請求項１記載の固体高分子形燃料電池用触媒混合体の製造方法。 The ratio of the cation exchange resin in the cation exchange resin solution to the cation exchange resin in the mixture Y in the fourth step is 5% by mass or more and 25% by mass or less. Of producing a catalyst mixture for solid polymer fuel cells. 第４の工程における噴霧乾燥温度が１００℃以上、１５０℃以下であることを特徴とする請求項１または２記載の固体高分子形燃料電池用触媒混合体の製造方法。 The method for producing a catalyst mixture for a polymer electrolyte fuel cell according to claim 1 or 2, wherein the spray drying temperature in the fourth step is 100 ° C or higher and 150 ° C or lower. 請求項１、２または３記載の製造方法により製造された固体高分子形燃料電池用触媒混合体を備えることを特徴とする固体高分子形燃料電池。 A polymer electrolyte fuel cell comprising the catalyst mixture for a polymer electrolyte fuel cell produced by the production method according to claim 1, 2 or 3.
JP2005208836A 2005-07-19 2005-07-19 Method of manufacture for catalyst mixture for polymer electrolyte fuel cell and polymer electrolyte fuel cell using it Pending JP2007026952A (en)

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JP2008282605A (en) * 2007-05-09 2008-11-20 Toyota Motor Corp Catalyst powder producing method

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JP2008282605A (en) * 2007-05-09 2008-11-20 Toyota Motor Corp Catalyst powder producing method
JP4661825B2 (en) * 2007-05-09 2011-03-30 トヨタ自動車株式会社 Catalyst powder production method

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