JP4879546B2 - Platinum colloid-supported zeolite and method for producing the same - Google Patents

Description

  The present invention relates to a method for producing a zeolite carrying platinum colloid and a novel platinum colloid-carrying zeolite obtained by the production method. This platinum colloid-supported zeolite is extremely useful as a material for an electrode catalyst for a fuel cell, for example.

In recent years, in relation to energy and environmental problems, a fuel cell has attracted attention as a power generation system that uses clean hydrogen as an energy source and generates no greenhouse gas such as CO _{2 with} no pollution. Such fuel cells have been fully developed and researched for use in fixed facilities such as homes and offices, and mobile facilities such as automobile and mobile phone batteries.

  A fuel cell is a device that converts chemical energy of a fuel to be used into electric energy using an electrochemical reaction, and is composed of an electrolyte, an anode electrode, and a cathode electrode. In addition, a catalyst is required to effectively promote the chemical reaction of the fuel.

  Fuel cells are classified according to the electrolyte used, and are classified into alkaline electrolyte type, solid polymer electrolyte type, phosphoric acid type, molten carbonate type, and solid electrolyte type. At this time, in the solid polymer electrolyte type and the phosphoric acid type, the charge transfer body is a proton, and it is also called a proton type fuel cell.

Examples of the fuel used in the fuel cell include hydrocarbon fuels such as natural gas, LP gas, city gas, alcohol, gasoline, kerosene, and light oil.
Such hydrocarbon fuel is first converted into hydrogen gas and CO gas by a reaction such as steam reforming and partial oxidation, and the CO gas is removed to obtain hydrogen gas. This hydrogen is supplied to the anode, dissociated into protons (hydrogen ions) and electrons by the metal catalyst of the anode, the electrons flow to the cathode while working through the circuit, and the protons (hydrogen ions) diffuse through the electrolyte membrane and become the cathode. In the cathode, the electrons, hydrogen ions, and oxygen supplied to the cathode are converted into water and diffused in the electrolyte membrane. That is, it is a mechanism for taking out an electric current in the process of supplying water with oxygen and hydrogen derived from fuel gas.

As a cathode electrode used in such a fuel cell, a catalyst layer (thin film) made of a metal component such as Pt, Pt—Ni, Pt—Co, Pt—Cu, etc. is formed on a porous support layer by sputtering, As an anode electrode, a catalyst layer (thin film) made of metal components such as Pt—Ru, Pt—Fe, Pt—Ni, Pt—Co, and Pt—Mo, which has high resistance to CO poisoning, is formed on the porous support layer by sputtering. What has been formed is being considered.

Carbon and zeolite are typical examples of the porous material used as a catalyst carrier. In particular, a carrier made of zeolite is mainly a catalyst for petroleum refining, taking advantage of its catalytic activity function, adsorption function, cation exchange capacity, and molecular sieve action. Used for exhaust gas purification and adsorbent. As a method for supporting platinum on a zeolite carrier, tetraammineplatinum (II) nitrate [Pt (N
[Pt (NH ₃ ) ₄ ] ²⁺ using an aqueous solution of a tetraammine platinum (II) complex salt such as H ₃ ) ₄ ] (NO ₃ ) ₂ , tetraammine platinum (II) dichloride [Pt (NH ₃ ) ₄ ] Cl ₂ There is known a method of preparing a platinum-supported zeolite catalyst by exchanging ions with cations of zeolite and supporting them, calcining the supported platinum ammine complex ions in air, and heat-treating them in a hydrogen atmosphere. Yes. (Arai Hiromichi, “ion exchange catalyst”, catalyst, vol. 19, P. 365-372 (1977), Non-Patent Document 1). In this method, platinum ions are said to be dispersed and supported inside the zeolite, and a considerable amount of platinum is distributed from the outer surface of the zeolite in the deep direction. In this case, there is a problem that platinum supported in the deep direction cannot be effectively used for the reaction that occurs near the surface of the supported catalyst.

  JP-A-10-15391 (Patent Document 1) discloses platinum chloride (IV) as a platinum complex cation to be used in a method for producing an outer layer supported platinum-supported zeolite catalyst in which a platinum complex cation is supported on a formed zeolite by ion exchange. It is disclosed to use an ammine complex ion of tetravalent platinum obtained by heat-reacting ammonium acid with excess ammonia water and then volatilizing and removing excess ammonia. The outer layer-supported platinum-supported zeolite catalyst needs to be calcined at 350 ° C. in the production process, and compared with the case where a divalent platinum ammine complex is used, the support inside the zeolite is suppressed, A considerable amount of tetravalent platinum ammine complex was supported inside the zeolite.

  The invention disclosed in Japanese Patent Application Laid-Open No. 2004-342505 (Patent Document 2) includes an anode, a cathode facing the anode, and a proton-conducting solid electrolyte layer interposed therebetween, and the anode is made of platinum. And a first supported catalyst in which at least one of platinum alloy is supported on a particulate carbon support, and at least one of platinum and platinum alloy is supported on a particulate hydrophilic support having higher hydrophilicity than the carbon support. And a weight ratio of the second supported catalyst to the first supported catalyst is in the range of 0.01 to 0.30. The present invention relates to a membrane electrode assembly, and zeolite is mentioned as an example of the hydrophilic carrier.

  As a method for producing this platinum-supported zeolite, a commercially available mordenite-type zeolite is dispersed in pure water, and then a hexahydroxo platinum nitric acid solution is added dropwise, and after adding pure water, the dispersion is filtered, and then filtered. The cake was washed, dispersed again in pure water, 0.01N aqueous ammonia solution was added to the dispersion to adjust the pH to about 9, and sodium borohydride as a reducing agent was added to the pure water. A method is disclosed in which a solution obtained by dissolving in water is dropped, and then the dispersion is filtered, and the obtained filter cake is dried at 80 ° C. for 48 hours. However, Patent Document 2 does not describe anything about effectively controlling the loading of platinum inside the zeolite.

Moreover, since these conventional methods require firing and reduction steps, an apparatus and a reducing agent for firing are necessary.
Japanese Patent Laid-Open No. 10-15391 JP 2004-342505 A Hiromichi Arai, “Ion Exchange Catalyst”, Catalyst, vol.19, p. 365-372 (1977)

As described above, the conventional method of supporting ions has a problem that the platinum utilization efficiency is lowered because platinum penetrates into the zeolite carrier.
Further, a method for sufficiently supporting a large amount of platinum colloid on a zeolite carrier is not known, and such a platinum colloid-supporting zeolite has not been known.

  An object of the present invention is to provide a production method in which the utilization rate of platinum is high, the catalytic action of platinum can be sufficiently exhibited, and the conventional firing and use of a reducing agent are not required.

Under such circumstances, the present inventors have intensively studied to solve the above problems. As a result, instead of using platinum ions (complexes), if a platinum colloid of nm order is supported on zeolite, It was thought that the catalytic action of platinum was more effectively exhibited than the zeolite catalyst supporting platinum ions, and all the problems of the prior art could be solved. In addition, the inventors considered that there is an advantage that it does not require a calcination step or use of a reducing agent as in the conventional method for producing platinum-carrying zeolite carrying platinum ions.

  However, simply mixing the zeolite powder and the platinum colloid cannot sufficiently support the platinum colloid. Therefore, the present inventors have further studied the conditions suitable for supporting the platinum colloid. As a result, if the platinum colloid is supported on the zeolite carrier in the presence of specific ions, the platinum colloid can be efficiently used. Thus, the inventors have found that the catalyst can be supported on the surface of the support and can effectively exhibit a catalytic function without being detached, and the present invention has been completed.

In addition, the technology for supporting platinum ions on the zeolite carrier is known, but the technology for supporting platinum colloid on the zeolite carrier has not been known.
The first invention of the present application is a method for producing a platinum colloid-supported zeolite in which a platinum colloid having an average particle diameter of 1 to 100 nm is supported on the zeolite in the presence of Pt ions or Au ions.

  In the second invention of the present application, Pt ions or Au ions are added to a zeolite suspension (zeolite solid content: 100 parts by weight) in an amount of 5 to 90 parts by weight in terms of metal elements and mixed at 15 to 40 ° C. Is prepared by adding 10 to 120 parts by weight of platinum colloid having an average particle diameter of 1 to 100 nm in terms of metal element and mixing at 15 to 40 ° C.

According to a third invention of the present application, in the first and second inventions, the Pt ions are chloroplatinic acid, potassium platinum (IV) chloride, sodium platinum (IV) chloride, potassium tetranitroplatinum (II), It is derived from one or more platinum compounds selected from the group consisting of sodium hexahydroxoplatinum (IV) hydrate, dinitrodiammine platinum nitrate, dinitrodiammine platinum ammonia or tetraamminedichloroplatinum hydrate,
A platinum colloid-supported zeolite characterized in that the Au ion is derived from one or more gold compounds selected from the group consisting of chloroauric acid, sodium gold sulfite, potassium gold cyanide or sodium gold cyanide. It is a manufacturing method.

A fourth invention of the present application is a platinum colloid-supported zeolite produced by the first to third inventions.
A fifth invention of the present application is the platinum colloid-supported zeolite according to the fourth invention, wherein platinum colloid having an average particle diameter of 1 to 100 nm is supported on a zeolite carrier in an amount of 3 to 60% by weight.

According to the present invention, it is possible to provide a platinum colloid-carrying zeolite that can reduce the amount of platinum inside the carrier that does not contribute to the catalytic action and is highly active in a small amount.
Such a platinum colloid-supported zeolite is suitable as an electrode catalyst for a fuel cell.

The present invention will be described below.
The method for producing a platinum colloid-supporting zeolite of the present invention is characterized in that a platinum colloid having an average particle diameter of 1 to 100 nm is supported on the zeolite in the presence of Pt ions or Au ions. If it manufactures by such a method, a desired platinum colloid carrying zeolite can be manufactured.

As a specific production method, Pt ions or Au ions are added to a zeolite suspension (100 parts by weight of zeolite solids) in an amount of 5 to 90 parts by weight in terms of metal elements and mixed, and the average particle diameter is 1 to 10 to 120 parts by weight of 100 nm platinum colloid in terms of metal element is added and mixed. The temperature at which Pt ions or Au ions are added to and mixed with the zeolite suspension is not particularly limited, but can be mixed, for example, at a temperature of 15 ° C. or higher. Mix in the range of 40 ° C. Also, the temperature at which platinum colloid is added to and mixed with the zeolite suspension mixed with Pt ions or Au ions is not particularly limited, and for example, mixing at a temperature of 15 ° C. or higher is possible. Usually, it is mixed in the range of 15 to 40 ° C.

Zeolite Zeolite used as a carrier in the present invention is not particularly limited, and a zeolite usually used as an adsorbent, a catalyst, a catalyst carrier or the like can be used. Examples thereof include A type zeolite, faujasite type zeolite (X type, Y type zeolite), L type zeolite, mordenite type zeolite, FMI type zeolite (ZSM-5 type zeolite), β type zeolite and the like. be able to. It should be noted that both synthetic zeolites and naturally occurring zeolitic minerals can be used as the carrier in the present invention.

Such a zeolite is not particularly limited in its shape. As for the size of the zeolite, typically those having a particle diameter in the range of 10 nm to 10 μm, preferably 1 to 3 μm are used. As the zeolite carrier, a zeolite having a size equal to or larger than the supported platinum colloid is used. Usually, the zeolite carrier having a size (average particle size) of at least 10 times the average particle size of platinum colloid is used.
As long as the particle diameter is in the above range, even aggregated zeolite particles can be used, but desirably they are used as dispersed (unaggregated state) as much as possible. Further, the zeolite can be used after ion exchange with a desired cation in advance.

  In general, it is difficult to obtain zeolite having an average particle size of less than 10 nm. In addition, when zeolite having an average particle diameter exceeding 10 μm is used, it is not easy to uniformly support platinum colloid on the surface of the zeolite carrier.

The zeolite used in the present invention is preferably calcined in a steam atmosphere.
The specific surface area of the zeolite carrier used in the present invention, SiO ₂ / Al ₂ O ₃ , is not particularly limited, but for example, the specific surface area is 400 to 900 m ² / g, SiO ₂ / Al ₂ O _3. A (molar ratio) of 2 or more is used. By using such a zeolite carrier, as will be described later, a platinum colloid-carrying zeolite in which 3 to 60% by weight of a platinum colloid is carried with respect to the zeolite carrier can be obtained.

The shape of the zeolite carrier is not particularly limited, and may be in the form of a powder, or may be formed into a small sphere or a pellet.
The zeolite suspension can be prepared by adding water to the zeolite, stirring at room temperature for about 1 to 10 minutes, and crushing with a homogenizer or the like. Here, usually, 800 to 1300 parts by weight of deionized water is added to 100 parts by weight of zeolite.

The zeolite suspension thus obtained may be further diluted by adding water as necessary for operation. Deionized water is preferably used as the dilution water.
Pt ions or Au ions Next, Pt ions or Au ions are added to the zeolite suspension. Pt ions or Au ions are usually supplied by adding a platinum compound or a gold compound capable of generating Pt ions or Au ions to the zeolite suspension.

  The amount of these compounds added is 5 to 90 parts by weight, preferably 10 to 80 parts by weight, as Pt ions or Au ions, with respect to 100 parts by weight of the solid content of the zeolite support in the zeolite suspension. When the addition amount of Pt ions or Au ions is less than 5 parts by weight, a sufficient supporting effect on the zeolite carrier may not be obtained even if platinum colloid is added. Further, even if it is added in excess of 90 parts by weight, the effect of supporting the platinum colloid on the zeolite carrier is not changed, so that further addition is not necessarily required.

  These compounds are used after being dissolved in a solvent, if necessary. When a solid platinum compound or gold compound is added to the zeolite suspension, it is necessary to sufficiently perform an operation such as stirring until the platinum compound or gold compound is sufficiently dissolved and ions can be generated.

The Pt ion is not limited in terms of valence, and any of Pt ²⁺ , Pt ⁴⁺ , and Pt ⁶⁺ can be used.
The platinum compound serving as a Pt ion supply source is not particularly limited as long as it generates Pt ions in the zeolite suspension. For example, chloroplatinic acid, potassium chloroplatinum (IV), sodium chloroplatinum (IV), tetranitroplatinum (II) potassium, sodium hexahydroxoplatinum (IV) hydrate, dinitrodiammine platinum nitrate, dinitrodiammine platinum ammonia Or 1 or more types of platinum compounds chosen from tetraammine dichloro platinum hydrate are mentioned. Further, the gold compound serving as the supply source of Au ions is not particularly limited as long as it generates Au ions in the zeolite suspension. For example, one or more gold compounds selected from chloroauric acid, sodium gold sulfite, potassium gold cyanide, or sodium gold cyanide can be used. As described above, these platinum compounds and gold compounds may be added as they are, or may be added after diluting in a solvent.

The type of the solvent is not particularly limited as long as it can dissolve the platinum compound or the gold compound without being reactive with the platinum compound or the gold compound.
Such solvents include water;
Alcohols such as methanol, ethanol, isopropanol, n-butanol, methyl isocarbinol;
Ketones such as acetone, 2-butanone, ethyl amyl ketone, diacetone alcohol, isophorone, cyclohexanone;
Amides such as N, N-dimethylformamide and N, N-dimethylacetamide;
Ethers such as diethyl ether, isopropyl ether, tetrahydrofuran, 1,4-dioxane, 3,4-dihydro-2H-pyran;
Glycol ethers such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol dimethyl ether;
Glycol ether acetates such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate;
Esters such as methyl acetate, ethyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, ethylene carbonate;
Aromatic hydrocarbons such as benzene, toluene, xylene;
Aliphatic hydrocarbons such as hexane, heptane, iso-octane, cyclohexane;
Halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, dichloropropane, chlorobenzene;
Sulfoxides such as dimethyl sulfoxide;
Examples thereof include, but are not limited to, pyrrolidones such as N-methyl-2-pyrrolidone and N-octyl-2-pyrrolidone.

  The temperature at which Pt ions or Au ions are added to the zeolite suspension and mixed is not particularly limited, but usually 15 ° C. or higher, preferably 15 to 40 ° C. is recommended. If it is less than 15 ° C., the support of the platinum colloid may eventually become insufficient, and even if it is added and mixed at 40 ° C. or higher, no change is observed in the final product. At this time, Pt ions or Au ions are added with sufficient stirring. The mixing time after the addition is not particularly limited, but is usually 1 to 60 minutes with stirring.

After sufficiently dispersing the ions in the platinum colloidal zeolite suspension, the platinum colloid in the range of an average particle diameter of 1 to 100 nm, preferably 3 to 50 nm, is converted into platinum element with respect to 100 parts by weight of the zeolite solid content. Add 10 to 120 parts by weight, preferably 20 to 110 parts by weight, and mix. Although the temperature at the time of mixing is not restrict | limited especially, Usually, 15 degreeC or more, Preferably the range of 15-40 degreeC is recommended. If it is less than 15 ° C., the support of the platinum colloid may be insufficient, and even if it is added and mixed at 40 ° C. or higher, there is no particular change in the product.

The mixing time is not particularly limited, but is usually stirred and mixed for 10 minutes to 120 minutes.
When the average particle diameter of the platinum colloid is 1 to 100 nm, the platinum colloid can be sufficiently dispersed and supported on the zeolite carrier. It is difficult to obtain a platinum colloid having an average particle size of less than 1 nm. In addition, when the average particle size of the platinum colloid exceeds 100 nm, it is not easy to sufficiently disperse and carry it on the zeolite carrier.

  As the platinum colloid, a platinum colloid solution dispersed in water or an organic solvent is usually used. The solid content concentration of platinum metal in the platinum colloid solution is not particularly limited, but for example, 0.01% by weight or more is suitable for use.

  When the amount of platinum colloid added is 10 to 120 parts by weight in terms of platinum element, the platinum colloid is sufficiently dispersed and supported on the zeolite carrier. If the amount is less than 10 parts by weight, there is no problem with the support, but since the absolute amount of platinum colloid supported on the zeolite carrier is small, the catalytic action by the platinum colloid may be insufficient. Even if platinum colloid is added, the amount supported on the zeolite carrier almost reaches saturation, and platinum colloid that cannot be supported increases, which is not efficient.

  In the method for producing a platinum colloid-supported zeolite of the present invention, the amount of platinum colloid supported on the zeolite carrier is determined by the production conditions of the present invention (temperature when Pt ions or Au ions are added, amount of Pt ions or Au ions added, platinum (The amount of colloid added, temperature at the time of platinum colloid addition, etc.), but also affected by the specific surface area or average particle size of the zeolite carrier used.

The manufacturing method of the platinum colloid used for this invention is not specifically limited, What was obtained with the well-known manufacturing method can be used.
Generally, a so-called combustion method and a precipitation method (metal salt reduction reaction method) are known as methods for producing platinum colloid.

In the combustion method, a metal ion solution is poured into hydrogen gas or phosphorus to cause a reduction reaction, and then heated by combustion to promote the reaction. The generated metal fine particles are received in a liquid dispersion medium, and after the reduction is completed. The method of stabilizing the metal colloid using a surfactant. Specifically, as disclosed in JP-A-61-271026, a hydrogen gas flame in which a mixed solution of a platinum aqueous solution and lower alcohol and hydrogen gas are sent from another supply system and burned. The mixed solution is merged immediately before, platinum is burned at 830 to 870 ° C., and the combustion flame is blown into a liquid dispersion medium in which a vortex flow reaching the bottom of the colloid generation tank is generated. And a production method as follows.

  The precipitation method (metal salt reduction reaction method) is said to be a production method capable of obtaining a platinum colloid having a higher concentration and higher activity than the combustion method. In this method, a reducing agent is added to a platinum ion solution, a reduction process is performed while controlling the temperature and pH, and platinum fine particles are precipitated in a liquid by controlling the temperature and pH. The temperature is controlled within a range of 20 to 80 ° C. from a low temperature to a high temperature, and the pH is maintained in the range of 4 to 11. The reduction treatment does not depend on a surfactant (protective colloid), but reduces metal ions to form a colloidal state. Is to keep

Platinum colloid-supported zeolite The platinum colloid-supported zeolite according to the present invention is obtained by the above production method, and is formed by supporting 3 to 60% by weight of a platinum colloid having an average particle diameter of 1 to 100 nm with respect to the zeolite support. It is characterized by this.

Unlike the conventional platinum-supported zeolite, such a platinum colloid-supported zeolite can exhibit excellent catalytic action because the active platinum colloid is dispersed on the surface of the zeolite carrier without penetrating inside. The reason why a platinum colloid-carrying zeolite having such excellent effects can be obtained by the production method of the present invention is not clear, but in the present invention, in the presence of Pt or Au ions, A platinum colloid is mixed in the liquid, and a kind of primer layer is formed on the surface of the zeolite carrier by adsorbing Pt ions or Au ions to silica or alumina present on the surface of the zeolite, in particular. it is conceivable that. On the primer layer, adsorption between platinum colloid and Pt ions or between platinum colloid and Au ions occurs, and it is estimated that the platinum colloid is supported well. As a result, it is considered that selectively active platinum colloid can be supported on the support surface. In addition, when Pt or Au ion does not exist, since the primer layer does not exist on the zeolite carrier surface, it is considered that the platinum colloid is difficult to adsorb on the carrier surface.

  Further, in the production method of the present invention, platinum colloid already in a metallic state is used, and therefore, a platinum colloid-supported zeolite can be obtained simply by supporting the platinum colloid on the zeolite carrier. For example, in the ion adsorption reduction method, the zeolite carrier in which Pt ions are present on the zeolite must be calcined and reduced to platinum metal, but the production method of the present invention requires such a calcining reduction treatment. However, it can be said that the method is simple and excellent in productivity.

The dispersion containing the platinum colloid-carrying zeolite obtained by the production method of the present invention may be diluted with water if necessary for the operation. Usually, the amount of water with respect to 100 parts by weight of zeolite can be diluted to a maximum of about 250,000 parts by weight.

In addition, if necessary, the obtained platinum colloid-supported zeolite may be subjected to a centrifugal separator, and desirably, washing may be repeated three times or more to remove remaining ions.
If desired, the platinum colloid-carrying zeolite may be separated from the purified platinum colloid-carrying zeolite dispersion. For separation, a centrifuge is usually used.
The separated platinum colloid-carrying zeolite is usually dried. As drying conditions, it is recommended to dry at 90 to 100 ° C. for 5 to 20 hours.

The platinum colloid-carrying zeolite of the present invention achieves a loading amount of 3 to 60% with respect to the zeolite carrier. For this reason, for example, in the use of exhaust gas purification catalyst, a small amount of platinum colloid-carrying zeolite can be used. High activity can be expected.

According to the present invention, a platinum colloid-supported zeolite excellent for an electrode catalyst of a fuel cell can be obtained. Such platinum colloid-supported zeolite can be used not only for fuel cells but also for exhaust gas treatment, deodorizers and the like.
[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples at all.

Preparation of zeolite suspension The zeolite suspension used in the examples and comparative examples was prepared as follows.
Ultrastable Y-type zeolite (powder, average particle size = 2 μm, SiO ₂ / Al ₂ O ₃ (molar ratio) = 5, containing 5 wt% Na ₂ O, NFA (out-lattice aluminum) 5.0 wt% Containing, specific surface area 600 m ² / g, lattice constant 24.57 Å, 12-membered ring structure)
0 g was collected, 833 g of water was added, stirred for 5 minutes with a three-one motor, and then pulverized with a homogenizer to obtain an ultrastable Y-type zeolite suspension (hereinafter referred to as “USY zeolite suspension”). Was prepared. Next, deionized water was added so that the zeolite solid content concentration was 10% by weight.

Preparation of a colloidal platinum solution To a metal salt aqueous solution obtained by dissolving 25 g of chloroplatinic acid hexahydrate (9 g in terms of platinum metal) in 16,000 g of pure water, a 1.0 wt. Platinum obtained by adding 1,660 g of a trisodium acid aqueous solution and 140 g of a sodium borohydride aqueous solution having a concentration of 0.1% by weight as a reducing agent and stirring and mixing at 20 ° C. in a nitrogen atmosphere to disperse platinum fine particles in water. A colloidal solution was obtained. Next, after the platinum colloid solution was purified by ultrafiltration membrane washing, the concentration was adjusted to obtain a platinum colloid solution having a concentration of 0.42% by weight in terms of platinum metal. The average particle size was 3 nm. In the following examples and comparative examples, this platinum colloid solution was used.

[Comparative Example 1]
2 g of the above USY zeolite suspension (zeolite solid content concentration 10% by weight) was weighed, and 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added thereto. The pH after the addition was 2.9. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifugal separator, and 500 g of water was further added, followed by washing for 3 minutes. Centrifugation and washing were repeated three times to prepare a zeolite from which the remaining platinum colloid, Cl ions, Au ions and the like were removed. The solid was dried at 90 ° C. to obtain a platinum colloid-supported zeolite.

[Example 1]
2 g of the above USY zeolite suspension (zeolite solid content concentration: 10% by weight) was weighed, and 14 g of chloroauric acid aqueous solution (containing 1% by weight of Au ions in the chloroauric acid aqueous solution) was added to this zeolite suspension. The mixture was added and stirred at 25 ° C. for 5 minutes.

  Next, 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added. The pH after the addition was 2.9. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifuge, and 500 g of water was further added and washed for 3 minutes. Centrifugation and washing were repeated three times to remove the remaining platinum colloid, Cl ions, Au ions, etc., and a zeolite with the platinum colloid supported on the surface was prepared. The solid was dried at 90 ° C. for 5 hours to obtain a platinum colloid-supported zeolite.

[Example 2]
To the same USY zeolite suspension as in Example 1, 10 g of an aqueous chloroauric acid solution (containing 1% by weight of Au ions in the aqueous chloroauric acid solution) was added and stirred at 25 ° C. for 5 minutes. Next, 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added.

  The pH after the addition was 3.5. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifuge, and 500 g of water was further added and washed for 3 minutes. Centrifugation and washing were repeated three times to remove the remaining platinum colloid, Cl ions, Au ions, etc., and a zeolite with the platinum colloid supported on the surface was prepared. The solid was dried at 90 ° C. for 5 hours to obtain a platinum colloid-supported zeolite.

[Example 3]
6 g of a chloroauric acid aqueous solution (Au ion was contained at 1 wt% in the chloroauric acid aqueous solution) was added to the same USY zeolite suspension as in Example 1, and the mixture was stirred at 25 ° C. for 5 minutes. Next, 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added. The pH after the addition was 4.1. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifuge, and 500 g of water was further added, followed by washing for 3 minutes. Centrifugation and washing were repeated three times to remove the remaining platinum colloid, Cl ions, Au ions, etc., and a zeolite with the platinum colloid supported on the surface was prepared. The solid was dried at 90 ° C. for 5 hours to obtain a platinum colloid-supported zeolite.

[Example 4]
2 g of an aqueous chloroauric acid solution (containing 1 wt% of Au ions in the aqueous chloroauric acid solution) was added to the same USY zeolite suspension as in Example 1, and the mixture was stirred at 25 ° C. for 5 minutes. Next, 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added. The pH after the addition was 4.8. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifuge, and 500 g of water was further added, followed by washing for 3 minutes.

  Centrifugation and washing were repeated three times to remove the remaining platinum colloid, Cl ions, Au ions, etc., and a zeolite with the platinum colloid supported on the surface was prepared. The solid was dried at 90 ° C. for 5 hours to obtain a platinum colloid-supported zeolite.

[Example 5]
14 g of an aqueous chloroplatinic acid solution (containing 1 wt% of Pt ions in the aqueous chloroplatinic acid solution) was added to the same USY zeolite suspension as in Example 1, and the mixture was stirred at 25 ° C. for 5 minutes. Next, 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added. The pH after the addition was 3.0. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifuge, and 500 g of water was further added, followed by washing for 3 minutes.

  Centrifugation and washing were repeated three times to remove the remaining platinum colloid, Cl ions, Pt ions, etc., and a zeolite with platinum colloid supported on the surface was prepared. The solid was dried at 90 ° C. for 5 hours to obtain a platinum colloid-supported zeolite.

[Example 6]
10 g of a chloroplatinic acid aqueous solution (containing 1 wt% of Pt ions in the chloroplatinic acid aqueous solution) was added to the same USY zeolite suspension as in Example 1, and the mixture was stirred at 25 ° C. for 5 minutes. Next, 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added. The pH after the addition was 3.5. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifuge, and 500 g of water was further added, followed by washing for 3 minutes.

Centrifugation and washing were repeated three times to remove the remaining platinum colloid, Cl ions, Pt ions, etc., and a zeolite with platinum colloid supported on the surface was prepared. The solid was dried at 90 ° C. for 5 hours to obtain a platinum colloid-supported zeolite.

[Example 7]
6 g of a chloroplatinic acid aqueous solution (containing 1 wt% of Pt ions in the chloroplatinic acid aqueous solution) was added to the same USY zeolite suspension as in Example 1, and the mixture was stirred at 25 ° C. for 5 minutes. Next, 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added. The pH after the addition was 4.3. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifuge, and 500 g of water was further added, followed by washing for 3 minutes.

  Centrifugation and washing were repeated three times to remove the remaining platinum colloid, Cl ions, Pt ions, etc., and a zeolite with platinum colloid supported on the surface was prepared. The solid was dried at 90 ° C. for 5 hours to obtain a platinum colloid-supported zeolite.

[Example 8]
2 g of a chloroplatinic acid aqueous solution (containing 1 wt% of Pt ions in the chloroplatinic acid aqueous solution) was added to the same USY zeolite suspension as in Example 1, and the mixture was stirred at 25 ° C. for 5 minutes. Next, 47 g of platinum colloid solution (platinum solid content 0.2 g, average particle diameter 3 nm) was added. The pH after the addition was 5.2. After stirring at 25 ° C. for 40 minutes, solid-liquid separation was performed with a centrifuge, and 500 g of water was further added, followed by washing for 3 minutes. Centrifugation and washing were repeated three times to remove the remaining platinum colloid, Cl ions, Pt ions, etc., and a zeolite with platinum colloid supported on the surface was prepared. The solid was dried at 90 ° C. for 5 hours to obtain a platinum colloid-supported zeolite.

  The platinum colloid-supported zeolite obtained in Examples 1 to 8 and Comparative Example 1 was analyzed for Pt. Moreover, the surface state was performed by transmission electron micrograph photography (TEM) observation. For transmission electron microscope photography, a transmission electron microscope (model number H-800, manufactured by Hitachi, Ltd.) was used.

  The Pt content in the platinum colloid-carrying zeolite was analyzed with an inductively coupled plasma emission spectrometer (hereinafter sometimes referred to as ICP) [model SPS1200A, manufactured by Seiko Instruments Inc.].

Moreover, the index of the dispersibility of platinum colloid is as follows.
A: There is no aggregation and the platinum colloid is uniformly supported as a whole with a primary particle size (about 3 nm) B: It is supported in a form (particle size about 3 nm to 5 nm) where two or three platinum colloids are joined in some places However, the state C in which the whole is highly dispersed is present as aggregated particles having a particle diameter of about 6 to 8 nm in some places, but the state D in which the whole is highly dispersed is about 10 to 15 nm in the place where the platinum colloid is in some places. There are aggregated particles. In addition, there is a clear unsupported part, and there is a difference in the support density. As a result, the average particle diameter of the platinum colloid supported on the zeolite support is shown in a transmission electron micrograph (magnification 250,000 times). The particle size of any 10 platinum colloids was measured and the average value was taken.

  The results are also shown in Table 1.

A cross-sectional photograph (magnification: 250,000 times) of the platinum colloid-carrying zeolite obtained in Example 6 is shown in FIG. 1, and a surface photograph of the platinum colloid-carrying zeolite obtained in Example 7 ( The magnification is 250,000 times).
As for the cross-sectional photograph, the dried platinum colloid-supported zeolite is embedded in a room temperature curing type epoxy resin, cured at room temperature for 7 hours to prepare a cured body, a diamond knife is attached to a microtrome, and the cured body is A sample was prepared by cutting to a thickness of about 30 nm, and a transmission electron micrograph was taken.

Cross-sectional photograph of platinum colloid-supported zeolite of Example 6 (magnification 250,000 times) Surface photograph of the platinum colloid-supported zeolite of Example 7 (magnification 250,000 times)

Claims (5)

  A method for producing a platinum colloid-supporting zeolite, comprising supporting a platinum colloid having an average particle diameter of 1 to 100 nm on a zeolite in the presence of Pt ions or Au ions.   To the zeolite suspension (zeolite solid content 100 parts by weight), Pt ions or Au ions are added in an amount of 5 to 90 parts by weight in terms of metal elements, and mixed at 15 to 40 ° C., where the average particle size is 1 to 100 nm. The method for producing a platinum colloid-carrying zeolite according to claim 1, wherein the platinum colloid is added in an amount of 10 to 120 parts by weight in terms of a metal element and mixed at 15 to 40 ° C.   The Pt ions are chloroplatinic acid, potassium chloroplatinate (IV), sodium chloroplatinate (IV), potassium tetranitroplatinum (II), sodium hexahydroxoplatinate (IV), dinitrodiammine platinum nitrate, dinitro It is derived from one or more platinum compounds selected from the group consisting of diammine platinum ammonia or tetraammine dichloroplatinum hydrate, and the Au ions are chloroauric acid, sodium gold sulfite, potassium gold cyanide or gold cyanide. The method for producing a platinum colloid-carrying zeolite according to claim 1 or 2, characterized in that it is derived from one or more gold compounds selected from the group consisting of sodium.   A platinum colloid-supported zeolite produced by the production method according to claim 1.   The platinum colloid-carrying zeolite according to claim 4, wherein a platinum colloid having an average particle diameter of 1 to 100 nm is carried by 3 to 60% by weight with respect to the zeolite carrier.