JP2008126211A - Method for producing metal support porous body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a metal support porous body, which is convenient by reducing the number of steps and enables cost reduction. <P>SOLUTION: The method for producing a metal support porous body comprises a step of reducing a divalent platinum ion to platinum by using a tertiary amine in a solvent under the presence of a porous body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a method for producing a metal-supporting porous body.

The metal-supported porous body in which platinum is supported on the porous body is used as a fuel cell electrode catalyst, an exhaust gas purification catalyst, a sensor material for a gas detector, and the like. In these applications, platinum is supported for the purpose of expressing the catalytic activity that occurs on the surface of the platinum metal. To improve the function as a battery or catalyst, fine particles with a large specific surface area are made porous. It is required to be carried on

As a method for producing such a metal-supporting porous body, a method of supporting platinum particles on a carbon carrier using a colloidal solution containing platinum colloid is known (Patent Documents 1 to 3). However, these methods require a step of producing a colloidal solution and a step of supporting platinum particles on a carbon support using the colloidal solution, and thus it is desired to provide a simpler production method.

Patent Document 4 discloses a method of preparing a dispersion solution in which carbon powder and a platinum complex are dispersed in water, adding a buffering agent to the dispersion solution, and then adding a reducing agent to reduce and precipitate platinum on the surface of the carbon powder. It is disclosed. However, in such a method, since a reducing agent having a strong reducing power is used, it is necessary to control reaction conditions in order to support fine platinum particles in the carbon powder. For this reason, a step of adding a buffering agent different from the reducing agent is required, so that there is still room for improvement in terms of the number of steps and cost.

In Patent Document 5, a conductive carrier material is suspended in water, an aqueous solution of a platinum-soluble compound is added to the suspension, and the pH value of the suspension is increased to 7 to 9 by adding an alkaline solution. And a method of precipitating platinum on a support material by reduction using a reducing agent is disclosed. However, the method described in Patent Document 5 is to deposit a metal by using a strong reducing agent, and in order to obtain a fine particle size, a step of adding an alkaline solution before the reaction. However, there is still room for improvement in terms of the number of processes and cost.

Patent Document 6 discloses a method for producing a platinum organosol. Patent Document 6 does not relate to a method for producing a metal-supporting porous body, but relates to a metal ultrafine particle organosol. The method described in Patent Document 6 is a method of adding another additive (alkylamine and / or a compound thereof) before adding a strong reducing agent, similarly to the methods described in Patent Documents 4 and 5. .

As a method for producing a platinum colloid aqueous solution, Patent Document 7 discloses a platinum colloid obtained by mixing a divalent platinum compound and an amine compound in an aqueous solution containing a high molecular weight pigment dispersant, and reducing the divalent platinum compound. A method of obtaining particles is disclosed. However, the method described in Patent Document 7 is not related to a method for producing a metal-supporting porous body, and is a method using a polymer pigment dispersant in addition to a reducing agent.

In addition, as a method for producing a porous body carrying a platinum alloy, in Patent Document 8, a step of carrying platinum on a carbon support and adding a alkali to a salt solution of another metal prepared a hydroxide. A step of preparing a hydroxide by adding a protective colloid agent, a step of adding and mixing platinum-supported carbon to the obtained colloid solution, filtering, and a platinum-supported carbon after filtration And a process of alloying by heat treatment at a temperature of 5 ° C. As a method of supporting platinum on a carbon support in this method, only a method of reducing with hydrazine after basic preparation is described, and it has the same problem as the method described above.

JP 2001-93531 A JP 11-47595 A JP 2003-123775 A JP 2004-335252 A JP-A-10-334925 JP 2006-104572 A JP 2002-285207 A JP-A-4-118860

In view of the above-mentioned present situation, the present invention has an object of providing a method for producing a metal-supporting porous body capable of reducing the cost because the number of steps is small and simple, and the reaction is easily controlled. It is what.

The present invention is a method for producing a metal-supporting porous body, comprising a step of reducing divalent platinum ions to platinum with a tertiary amine in a solvent in the presence of the porous body.
In this invention, it is preferable that the usage-amount of a tertiary amine is 1-20 equivalent per 1 mol of platinum atoms in platinum ion in conversion of N amount.
In the present invention, the mass ratio of platinum (in metal equivalent) / porous body in the solvent during the reaction is preferably 20/80 to 80/20.

The present invention also provides a divalent platinum ion, gold, silver, ruthenium, rhodium, palladium, osmium, rhenium, iridium, copper, chromium, manganese, iron, indium, molybdenum in a solvent in the presence of a porous material. At least one metal ion or complex ion selected from the group consisting of tin, cobalt, nickel, zinc, antimony, bismuth, vanadium, niobium, tantalum and tungsten is simultaneously added to platinum and the above metal by a tertiary amine. It is a manufacturing method of the metal carrying | support porous body characterized by having the process to reduce | restore.

In the present invention, the divalent platinum ion is preferably a tetracoordinate platinum complex ion.
The divalent and tetracoordinate platinum complex ion is preferably a tetrachloroplatinum (II) acid ion.

In the present invention, the porous body preferably has conductivity. The porous body is preferably conductive carbon black or a ceramic material.
In the present invention, the tertiary amine is preferably an aliphatic, aralkyl or alicyclic tertiary amine, and the solvent is preferably water or an aqueous medium.

The porous body preferably has a BET specific surface area of 200 to 1500 m ² / g. The reduction is preferably performed at a reaction temperature of 15 to 100 ° C. for a reaction time of 10 minutes to 50 hours.
The present invention is described in detail below.

The method for producing a metal-supporting porous body of the present invention includes a step of reducing divalent platinum ions to platinum with a tertiary amine in a solvent in the presence of the porous body. That is, the present invention uses a divalent platinum ion, which is more easily reduced than a tetravalent platinum ion, as a raw material. Therefore, the metal can be deposited under mild reduction conditions in the presence of a tertiary amine, the reaction can be easily controlled, and the cost can be reduced.

In the present invention, a tertiary amine is used as the reducing agent. Since the reduction reaction with an amine proceeds under mild conditions, a fine particulate metal can be easily deposited. For this reason, fine metal particles having a large specific surface area can be efficiently supported on the porous body.

In addition, since the unshared electron pair on the nitrogen atom of the amine acts as a ligand for the metal, if the complex is stabilized in the aqueous solution by coordination, the reduction reaction is difficult to proceed. For this reason, in order to obtain favorable reducibility, it is necessary to use an amine with low coordination ability. The tertiary amine has three aliphatic hydrocarbon groups around the nitrogen atom, and therefore has a low coordination ability due to a steric factor, and is thus presumed to facilitate the reduction reaction.

In the present invention, the reaction as described above is performed in the presence of a porous material. As a result, a porous body carrying a metal can be easily manufactured.

The divalent platinum ion is generated by dissolving a divalent platinum ion precursor (platinum compound) in a solvent. Examples of the divalent platinum ion precursor include those composed of two electron donors or electron donating functional groups for one platinum atom, and four electron donors or electron donating functional groups for one platinum atom. And those composed of groups.
Examples of the divalent platinum ion precursor composed of two electron donors or electron donating functional groups for one platinum atom include platinum fluoride (II), platinum chloride (II), platinum bromide ( II), platinum iodide (II), platinum oxide (II), platinum cyanide (II) and the like.
Examples of the divalent platinum ion precursor composed of four electron donors or electron donating functional groups for one platinum atom include sodium tetrachloroplatinate (II) tetrahydrate, tetrachloroplatinum ( II) Potassium acid, Tetrachloroplatinum (II) ammonium, Tetrabromoplatinum (II) acid dihydrate, Potassium tetranitroplatinum (II), Bis (2,4-pentanedionato) platinum (II), Dichlorodiammine Platinum (II), tetrachloroplatinum (II) acid, tetraammineplatinum (II), tetraammineplatinum (II) chloride n-hydrate, dinitrodiammineplatinum (II), dichlorobis (benzonitrile) platinum (II), bis ( Ethylenediamine) platinum (II) chloride, potassium tetrakis (thiocyanato) platinum (II), tetracyanoplatinum ( I) Potassium acid trihydrate, tetracyanoplatinum (II) barium acid tetrahydrate, dichlorobis (triphenylphosphine) platinum (II), iodo (methyl) bis (triethylphosphine) platinum (II), diphenylbis (triethyl) Phosphine) platinum (II), dichloro (phenylisocyanide) (triethylphosphine) platinum (II), bis (allyl) platinum (II), dichloro (1,5-cyclooctadiene) platinum (II), trans-1-cyclohexane Diamine dichloroplatinum (II), trans-d-cyclohexanediamine dichloroplatinum (II), dichlorobis (benzonitrile) platinum (II), dichloro (η-ethylene) platinum (II) dimer, dichloro (η-cyclohexene) platinum (II ) Dimers and the like.

Among the divalent platinum ion precursors composed of four electron donors or electron donating functional groups for one platinum atom, alkali metal salts or ammonium salts of tetracoordinate platinum complex ions are preferable. This is because these salts have high solubility in an aqueous medium and can be suitably used in the reduction step.

The solvent is not particularly limited, and examples thereof include an aqueous medium and an organic solvent.
Examples of the aqueous medium include water or a mixture of water and an organic solvent.
Of these, water is preferred. This is because it is safe in the manufacturing process, and the metal-supported porous body obtained by the production is also safe without the risk of explosion.
Moreover, as an organic solvent, a water-soluble thing is preferable, and can specifically mention monohydric or polyhydric alcohol and ether.
The method for producing a metal-supported porous body of the present invention is preferably carried out at a platinum content of 0.005 mol / l or more in terms of metal amount in the solvent during the reaction.
If the platinum content is less than 0.005 mol / l, it is difficult to sufficiently support the platinum particles on the porous body.

In the method for producing a metal-supporting porous body of the present invention, the mass ratio of platinum (metal equivalent amount) / porous body in the solvent during the reaction is preferably 20/80 to 80/20. It is suitable for the fuel cell and exhaust gas purification catalyst to be within the above range. When the mass ratio is less than 20/80, the catalyst layer must be thickened when the metal-supported porous body is used as an electrode catalyst for a fuel cell. May not be sufficiently obtained. On the other hand, if the mass ratio exceeds 80/20, when used as a fuel cell electrode catalyst or the like, the catalytic activity becomes too high and there is a risk of ignition.

The method for producing a metal-supported porous body of the present invention also includes divalent platinum ions, gold, silver, ruthenium, rhodium, palladium, osmium, iridium, copper, chromium, in a solvent in the presence of the porous body. Ion of at least one metal selected from the group consisting of manganese, iron, indium, molybdenum, tin, cobalt, nickel, zinc, antimony, bismuth, vanadium, niobium, tantalum, rhenium and tungsten (hereinafter referred to as second component metal) Or it has the process of reduce | restoring a complex ion to platinum and a 2nd component metal simultaneously with a tertiary amine. Depending on the purpose, it may be necessary to use these metals in combination with platinum. In such a case, the above reduction reaction is performed in the presence of these metals. The physical properties can be obtained. In this method, it is possible to obtain a metal-supporting porous body that supports at least two kinds of metals in one step. The metal-supporting porous body here is a metal-supporting porous body containing at least platinum and having one or more of the second component metals. In other words, the metal-supporting porous body here has a structure in which metal fine particles are supported on the surface of the porous body. Further, the supported metal fine particles include those having a structure in which platinum and one or more kinds of metals as the second component metal are alloyed (composited) in the particles, or platinum. This refers to those supported in a state where fine particles and metal fine particles of the second component metal are mixed, including those supported in a form in which alloy fine particles and single metal fine particles are mixed. The supported metal fine particles include those in which individual metal fine particles are supported in an independent state and those supported in a state including a form in which metal fine particles are aggregated.

As the second component metal, ruthenium is preferable. This is because when the metal-supported porous body is used as an electrode catalyst for a fuel cell, the resistance to poisoning by carbon monoxide can be improved by performing the above reduction reaction in the presence of ruthenium at the anode.

When the reduction reaction is performed in the presence of the second component metal, the content of platinum and the second component metal in the solvent preferably satisfies the following relationship. That is, the mass ratio of platinum and the second component metal to the porous body is preferably (platinum + second component metal; metal amount conversion) / porous body = 20/80 to 80/20. This is because by adjusting the metal content within the above range, a metal-supporting porous body having sufficient resistance to poisoning by carbon monoxide and catalytic activity can be produced. The mass ratio of platinum and the second component metal in terms of metal varies depending on the use of the metal-supported porous body and the type of the second component metal, and is not particularly limited. The mass ratio is preferably 20/80 to 99.5 / 0.5.

In the present invention, the reduction is performed in the presence of the porous body. The reason for using the porous body is to increase the catalytic activity by increasing the reaction area. The porous body preferably has a micropore of less than 2 nm or a mesopore of 2 to 30 nm and a specific surface area of 200 to 1500 m ² / g.
The porous body is not particularly limited, and examples thereof include inorganic substances such as carbon, ceramic materials and clay minerals, single or complex oxides of metals or metalloids, and sulfides. The porous body preferably has electrical conductivity, particularly when used as an electrode material, and specifically carbon is preferred.

As the carbon, a commonly used carbon material can be used. Of these, carbon black such as channel black, furnace black, acetylene black, and ketjen black, graphite, nanotube, fullerene, activated carbon, and the like are preferable. In addition, it is good also as using the thing to which the hydrophilic treatment was given as said carbon. Examples of such carbon include those having an acidic group introduced on the surface.
Further, when the metal-supported porous body is used as a catalyst for purifying exhaust gas, the porous body preferably has heat resistance and gas degradation resistance, and specifically, ceramic materials, clay minerals, etc. Inorganic, metal or metalloid single or complex oxides, sulfides, chalcogenides and the like are preferred. Among them, inorganic substances such as zeolite, apatite, zirconium phosphate, clay minerals; silicon oxide, aluminum oxide, vanadium oxide, titanium oxide, iron oxide, nickel oxide, cobalt oxide, molybdenum oxide, niobium oxide, cerium oxide, lanthanum oxide, oxidation Single or complex oxides of metals or metalloids such as boron, zirconium oxide, tantalum oxide, tungsten oxide and magnesium oxide; sulfides; chalcogenides and the like are preferable. The shape of the metal-supporting porous body obtained using the porous body as described above is not particularly limited, and for example, it can be used after being processed into a pellet shape. The metal-supporting porous body can be used by forming it on a support (for example, a honeycomb support or the like) or applying it to the support.

The BET specific surface area of the porous body is not particularly limited, but is preferably 200 to 1500 m ² / g as described above. This is because a metal-supporting porous body having excellent catalytic activity can be obtained.

As the tertiary amine, a water-soluble aliphatic tertiary amine is preferably used. This is because the reaction can easily proceed when the reaction is carried out in an aqueous medium. The water-soluble aliphatic tertiary amine may have one or more functional groups such as a hydroxyl group and a carbonyl group in the alkyl group, and may be, for example, an alkanolamine. Examples of the water-soluble aliphatic tertiary amine include diethylmethylamine, triethylamine, dimethylaminoethanol, diethylaminoethanol, triethanolamine, methyldiethanolamine, and dimethylaminopropanol. Of these, alkanolamines are preferred, monoalkanolamines are more preferred, and 2-dimethylaminoethanol is even more preferred. The substituent of the aliphatic tertiary amine is preferably an alkyl group, an ether group or a polyether group, and the terminal of the substituent is preferably a hydrogen group or a hydroxyl group. In the present invention, an aralkylamine or an alicyclic amine can be used as the water-soluble tertiary amine. Examples of aralkylamines include N, N-dimethylbenzylamine, N, N-diethylbenzylamine, N, N-dimethylphenethylamine, N, N-diethylphenethylamine, N, N, N ′, N′-tetramethylxylene. A diamine etc. can be mentioned. Examples of the alicyclic amine include N-methylpiperidine, piperazine, and pyrrolidine.
As the aliphatic tertiary amine, those commercially available can also be used. Examples of the commercially available products include Esomine C / 12, Esomin C / 15, Esomin C / 25, Esomine T / 12, Esomine T / 15, Esomine T / 25, Esomine S / 15, Esomine S / 25, Esomine O / 12, Esomin O / 17, Esomin O / 20, Esomin HT / 12, Esomin HT / 14, Esomin HT / 17, Esomin SAJ-103, Esomin SA2Y-103 (manufactured by Lion Akzo) it can. These may be used alone or in combination of two or more. Among the above commercially available products, esomine C / 15, esomine C / 25, esomine T / 15, esomine T / 25, esomine S / 25, esomine SAJ-103 or esomine SA2Y-103 are preferred. This is because these commercially available products exhibit water solubility.

When the second component metal is not included in the solvent, the amount of the tertiary amine used is preferably 1 to 20 equivalents per 1 mole of platinum metal in platinum ions in terms of N amount. If the amount is less than 1 equivalent, the reduction may not be performed sufficiently. If it exceeds 20 equivalents, a large amount of washing water is required in the washing step as a post-treatment.

In the present invention, a reducing agent other than the tertiary amine can be used in combination. Examples of such a reducing agent include hydrazine compounds, citric acid, tartaric acid, ascorbic acid, formic acid, malic acid, sulfoxylic acid, and derivatives thereof.
Among the conventional reducing agents, citric acid, tartaric acid, ascorbic acid, formic acid, and malic acid are preferable because they are easily available. In addition, when citric acid, tartaric acid, and ascorbic acid are added to the system as they are, they may form a salt with the amine compound and suppress the functional expression of the amine compound. Therefore, it is preferable to use a salt form. However, it is preferable not to use these compounds in consideration of reduction in the number of steps and cost reduction.

In the reduction step, divalent platinum ions contained in the solvent are reduced with a tertiary amine in the presence of a porous material. The order of adding these to the solvent is not particularly limited, but it is preferable to add the other to the solvent containing either the platinum ion or the tertiary amine and the porous body. Especially, it is preferable to add the platinum ion to a solvent containing the tertiary amine and the porous body. This is because the tertiary amine functions as a wettability aid or a dispersion aid for the porous body.

In the reduction step, the progress of the reduction reaction can be confirmed by mixing the divalent platinum ion and the tertiary amine so that the supernatant after standing exhibits a colorless to yellow color.
In the reduction step, reduction is preferably performed at a reaction temperature of 15 to 100 ° C. for a reaction time of 10 minutes to 50 hours. It is because fine particulate metal can be easily deposited by performing the reduction under these conditions.

The solvent containing the metal-supported porous material thus obtained contains a salt generated by reduction or, in some cases, an amine compound in addition to the porous material supporting platinum. Since these components may adversely affect the catalytic activity of the metal-supported porous body, it is preferable to remove them. These components can be removed by a known method such as ultrafiltration or electrodialysis until the electric conductivity of the filtrate reaches a target value. The target value is not particularly limited, but is preferably 10 μS / cm or less. This is because a metal-supporting porous material having sufficient catalytic activity can be obtained.

The average particle diameter of platinum in the metal-supported porous body obtained by the above-described production method is preferably less than 5 nm. When it is 5 nm or more, it becomes difficult to use as a catalyst. A more preferable average particle diameter is 2 to 3 nm. In addition, an average particle diameter can be determined by reading from the electron micrograph etc. of platinum particle | grains, or measuring with X-ray diffraction, an analytical instrument etc., for example.

The amount of platinum supported on the metal-supporting porous body is preferably 20 to 80% by mass. This is because sufficient catalytic activity can be exhibited. If it is less than 20% by mass, the catalyst layer must be thickened when used as an electrode catalyst for a fuel cell, so that the diffusibility of fuel gas or the like is lowered, and there is a possibility that sufficient catalytic performance may not be obtained. On the other hand, when it exceeds 80 mass%, when used as a fuel cell electrode catalyst or the like, the catalytic activity becomes too high and there is a risk of ignition.

The BET specific surface area of the metal-supporting porous body is not particularly limited, but is preferably 50 to 1000 m ² / g. This is because a metal-supporting porous body having a BET specific surface area within this range has excellent catalytic activity.

According to the said manufacturing method, a metal carrying | support porous body can be manufactured simply, reducing the number of processes. Moreover, a dry process such as drying is unnecessary, and a composition in which the metal-supported porous body is dispersed can be obtained only by a wet process. When the porous body is in the form of a conductive powder, other solvent is used by mixing the conductive resin into the composition without removing the solvent from the composition obtained by the above production method. An ink-like electrode catalyst (catalyst ink) can be obtained without any problems. Alternatively, the solvent in the composition in which the metal-supported porous body is dispersed may be replaced with another solvent, and the resulting composition may be mixed with a conductive resin to form an ink. The catalyst ink thus obtained can be used, for example, in the production of a polymer electrolyte fuel cell electrode. When the porous body is powdery, the composition obtained by the above production method is dried, and the resulting powdery metal-carrying porous body is heat-molded to form a molded product of the metal-carrying porous body. Can also be manufactured.

According to the method for producing a metal-supporting porous body of the present invention, the metal-supporting porous body can be easily produced with few steps, and the cost can be reduced.

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

[Example 1]
36.14 g of deionized water was added to 1.76 g of conductive carbon (Cabot Vulcan XC72R), mixed, and 2.68 g of 2-dimethylaminoethanol was further added, followed by stirring with a magnetic stirrer (700 rpm) at 80 ° C. The aqueous solution A was obtained.
An aqueous solution B was obtained by dissolving 2.50 g of potassium tetrachloroplatinate (II) (K ₂ PtCl ₄ ) in 25.00 g of deionized water.
The mass ratio of the conductive carbon in the total amount of the aqueous solution A and the platinum (metal amount) in the potassium tetrachloroplatinate (II) in the total amount of the aqueous solution B was 60/40.
The entire amount of the aqueous solution B was added to the total amount of the aqueous solution A while stirring, and the mixture was stirred at 700 rpm for 75 minutes while maintaining at 80 ° C.
Then, after stopping heating and cooling to room temperature with stirring, the solution containing the platinum-supporting porous material was filtered.
To this, 30 g of deionized water was added and filtered, and washing was performed to remove miscellaneous ion compounds adhering to the platinum-supporting porous material. This operation was performed until the electric conductivity of the filtrate was 10 μS / cm or less.
The obtained product was transferred to another container and dried using a vacuum dryer to obtain a platinum-supporting porous material.

[Example 2]
An aqueous solution C was obtained according to the preparation method for obtaining the aqueous solution A of Example 1 except that 3.52 g of 2-dimethylaminoethanol was added.
1.67 g of potassium tetrachloroplatinate (II) (K ₂ PtCl ₄ ) and 1.015 g of ruthenium (III) chloride trihydrate (RuCl ₃ .3H ₂ O) were added to 25.00 g of deionized water at room temperature. An aqueous solution D was obtained by dissolution.
The mass ratio of platinum (metal amount) in potassium tetrachloroplatinate (II) in the total amount of aqueous solution D to ruthenium (metal amount) in ruthenium (III) chloride trihydrate was 2/1.
The mass ratio of the carbon in the total amount of the aqueous solution C to the total (metal amount) of platinum in the potassium tetrachloroplatinate (II) in the total amount of the aqueous solution D and ruthenium in the ruthenium (III) chloride trihydrate (metal amount) is 60 / 40.
The total amount of the aqueous solution D was added to the total amount of the aqueous solution C while stirring, and the mixture was stirred at 700 rpm for 150 minutes while maintaining at 80 ° C.
Then, after stopping heating and cooling to room temperature with stirring, the solution containing the platinum / ruthenium composite-supported porous material was filtered.
To this, 30 g of deionized water was added, followed by filtration, and washing was performed to remove miscellaneous ion compounds adhering to the platinum / ruthenium composite-supported porous body. This operation was performed until the electric conductivity of the filtrate was 10 μS / cm or less.
The obtained product was transferred to another container and dried using a vacuum dryer to obtain a porous body supporting a platinum / ruthenium complex.

[Example 3]
An aqueous solution E was obtained according to the preparation method for obtaining Example A, except that silicon oxide (AEROPERL 300/30 manufactured by Nippon Aerosil Co., Ltd.) was used instead of conductive carbon.
The mass ratio of silicon oxide in the total amount of the aqueous solution E to platinum (metal amount) in the potassium tetrachloroplatinate (II) in the total amount of the aqueous solution B was 60/40.
The total amount of the aqueous solution B was added to the total amount of the aqueous solution E while stirring, and the mixture was stirred at 700 rpm for 75 minutes while maintaining at 80 ° C.
Then, after stopping heating and cooling to room temperature with stirring, the solution containing the platinum-supporting porous material was filtered.
To this, 30 g of deionized water was added and filtered, and washing was performed to remove miscellaneous ion compounds adhering to the platinum-supporting porous material. This operation was performed until the electric conductivity of the filtrate was 10 μS / cm or less.
The obtained product was transferred to another container and dried using a vacuum dryer to obtain a platinum-supporting porous material.

[Comparative Example 1]
36.14 g of deionized water was added to 1.76 g of conductive carbon (Cabot Vulcan XC72R), mixed, and 3.75 g of 2-dimethylaminoethanol was further added, followed by stirring with a magnetic stirrer (700 rpm) at 80 ° C. The aqueous solution F was obtained.
Hexachloroplatinic (IV) acid hexahydrate and _{(H 2 PtCl 6 · 6H 2} O) 3.12g was dissolved in deionized water 25.00 g, to obtain an aqueous solution G.
Example 1 was repeated except that the aqueous solution G was used instead of the aqueous solution B, and the aqueous solution F was used instead of the aqueous solution A.

[Comparative Example 2]
After adding 36.14 g of deionized water to 1.76 g of conductive carbon (VulcanXC72R manufactured by Cabot) and adding 1.84 g of 2-aminoethanol, the mixture was stirred at 700 rpm and heated to 80 ° C. The temperature was raised to obtain an aqueous solution H. Example 1 was repeated except that the aqueous solution H was used instead of the aqueous solution A.

[Comparative Example 3]
After adding 36.14 g of deionized water to 1.76 g of conductive carbon (Cabot Vulcan XC72R) and adding 2.58 g of 2-aminoethanol, stirring to 700 ° C. with a magnetic stirrer (700 rpm). The temperature was raised to obtain an aqueous solution I. Example 1 was repeated except that the aqueous solution G was used instead of the aqueous solution B, and the aqueous solution I was used instead of the aqueous solution A.

[Evaluation methods]
Using the aqueous solutions obtained in Examples 1 to 3 and Comparative Examples 1 to 3, the following methods were used for evaluation.
(1) Observation using transmission electron microscope and measurement of particle diameter The obtained porous body was observed and photographed using a transmission electron microscope (JEM-2000 manufactured by JEOL Ltd.). As a result, since the metal particles could be observed in the porous bodies according to Examples 1 to 3, the average particle diameter was measured with a caliper. As the average particle diameter, an average value of arbitrarily selected 10 particles was used. On the other hand, metal particles could not be observed in the porous bodies according to Comparative Examples 1 to 3.

1 and 2 are transmission electron micrographs of the metal-supporting porous material obtained in Example 1. FIG. In the figure, there are large particles and small particles attached to the particles. The large particles are conductive carbon, and the small particles are platinum particles. 1 and 2, it can be confirmed that platinum particles are uniformly supported on the surface of the conductive carbon.

(2) Measurement of BET specific surface area For the porous bodies according to Examples 1 to 3 in which metal particles could be confirmed, the specific surface area was measured by the BET method (nitrogen adsorption method).
Table 1 shows the results of the evaluation methods (1) and (2).

As shown in Table 1, in Examples 1 to 3, metal particles could be supported on the porous body, but in Comparative Examples 1, 2, and 3, metal particles could not be supported.
In Comparative Example 1, the tetravalent platinum ions generated in the solution by dissolving hexachloroplatinic the (IV) acid hexahydrate _{(H 2 PtCl 6 · 6H 2} O), aliphatic tertiary amines It is considered that the metal particles could not be supported on the conductive carbon because the metal could not be reduced to platinum metal.
That is, in order to reduce tetravalent platinum ions, it is necessary to donate four electrons per platinum atom, so a reducing agent having higher reactivity must be applied. However, it is considered that the reducing ability of the aliphatic tertiary amine was insufficient.
Further, since hexachloroplatinum (IV) acid is 6-coordinated, it is considered to be a complex having higher stability than a 4-coordinated complex. Therefore, even when an aliphatic tertiary amine acts on a hexacoordinate tetravalent platinum ion, the reaction is terminated by forming a stable complex between the aliphatic tertiary amine and the tetravalent platinum ion. It is presumed that the platinum-supporting porous body was not obtained because no reduction reaction occurred.

In Comparative Example 2, bivalent platinum ions could not be reduced to platinum metal with 2-aminoethanol, which is an aliphatic primary amine, so that metal particles could not be supported on the porous body. It is thought.
Therefore, of course, in Comparative Example 3, it was considered that tetravalent platinum ions could not be reduced to platinum metal with an aliphatic primary amine, so that metal particles could not be supported on the porous body. It is done.
Regarding these, as described above, since the lone electron pair on the nitrogen atom of the amine acts as a ligand for the metal ion, the metal complex is stabilized in the solvent by coordination. It is thought that this is because the reduction reaction is difficult to proceed.
That is, a primary amine such as 2-aminoethanol has only one substituent and has a small steric hindrance around the nitrogen atom, so that even if it is a 4-coordinate platinum complex, a stable platinum complex is formed. Therefore, it is presumed that the platinum-reducing porous body was not obtained because the platinum reduction reaction due to electron donation to platinum ions was not achieved.

In Comparative Example 3, even when an aliphatic primary amine that easily forms a stable complex is allowed to act on tetravalent platinum ions that are more difficult to be reduced, the reduction reaction of platinum ions is less likely to occur. It is presumed that the porous body was not supported.

The present invention relates to hydrogenation and dehydrogenation of hydrocarbons, purification of nitrogen oxides in exhaust gas of automobiles, etc., fuel cells, oxidation-reduction catalysts such as water generation with electricity generation by hydrogen and oxygen, chemical sensors, It can utilize suitably as a manufacturing method of the dope material of the electrode of a solar cell.

2 is a transmission electron micrograph (magnified 100,000 times) of a metal-supporting porous material obtained in Example 1. FIG. 2 is a transmission electron micrograph (magnified 250,000 times) of a metal-supporting porous material obtained in Example 1. FIG.

Claims (11)

A method for producing a metal-supporting porous material, comprising a step of reducing divalent platinum ions to platinum with a tertiary amine in a solvent in the presence of the porous material. The method for producing a metal-supporting porous body according to claim 1, wherein the amount of the tertiary amine used is 1 to 20 equivalents per mole of platinum atoms in platinum ions in terms of N amount. 3. The method for producing a metal-supporting porous material according to claim 1, wherein a mass ratio of platinum (amount in terms of metal) / porous material in the solvent during the reaction is 20/80 to 80/20. In the presence of a porous material, in a solvent, divalent platinum ions, gold, silver, ruthenium, rhodium, palladium, osmium, rhenium, iridium, copper, chromium, manganese, iron, indium, molybdenum, tin, cobalt, A step of simultaneously reducing ions or complex ions of at least one metal selected from the group consisting of nickel, zinc, antimony, bismuth, vanadium, niobium, tantalum and tungsten to platinum and the metal by a tertiary amine. A method for producing a metal-supporting porous material. The method for producing a metal-supporting porous body according to any one of claims 1 to 4, wherein the divalent platinum ion is a tetracoordinate platinum complex ion. 6. The method for producing a metal-supporting porous material according to claim 5, wherein the divalent and tetracoordinate platinum complex ion is a tetrachloroplatinum (II) acid ion. The method for producing a metal-supporting porous body according to any one of claims 1 to 6, wherein the porous body has conductivity. The method for producing a metal-supporting porous body according to claim 7, wherein the porous body is conductive carbon black or a ceramic material. The tertiary amine is an aliphatic, aralkyl or alicyclic tertiary amine,
The method for producing a metal-supporting porous body according to any one of claims 1 to 8, wherein the solvent is water or an aqueous medium. The method for producing a metal-supported porous body according to any one of claims 1 to 9, wherein the porous body has a BET specific surface area of 200 to 1500 m ² / g. The method for producing a metal-supporting porous body according to any one of claims 1 to 10, wherein the reduction is performed at a reaction temperature of 15 to 100 ° C for a reaction time of 10 minutes to 50 hours.

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