JP4646077B2 - Nanoparticle catalyst embedded in porous carbon support and method for producing the same - Google Patents

Description

  The present invention relates to a nanoparticle catalyst that can reduce the activation energy and promote the reaction, and a method for producing the same.

  At present, it has become clear that chemical, electrical, optical, magnetic, or mechanical properties that are completely different from the bulk state can be exhibited by making particles ultrafine to the order of several nanometers. Therefore, attempts have been made to develop various characteristics by making the particles ultrafine to the nano-order. It has also been clarified that catalyst particles exhibit high catalytic activity due to such a change in characteristics and an increase in surface active points when the diameter of the catalyst particles approaches several nanometers. However, when the particles are made ultrafine to the order of several nanometers, the surface energy becomes very large. In this case, the particles become unstable in dispersion and agglomerate to lose the characteristics.

Therefore, in patent document 1, the photocatalyst particle | grains whose primary particle diameter is 5-9 nm is included in the microcapsule of hollow porous silica (patent document 1).
JP 2003-096399 A

  However, the photocatalyst particles encapsulated in the hollow portion of the microcapsule are dispersed and stable by the microcapsule and can come into contact with the target substance. However, since the microcapsule is composed of silica having a low structural strength, It easily breaks, and once a part of the microcapsule is broken, the dispersion becomes unstable and agglomerates. As a result, there is a problem that the active sites on the surface are reduced and the catalytic activity is lowered. Moreover, the microcapsules made of silica are hydrophilic and have a low affinity with the organic compound that is the catalyst substance. In order to achieve a high catalytic activity, a structure capable of adsorbing or concentrating the catalyst material near the surface of the nanocatalyst particles is required. Furthermore, the porous material formed by utilizing the gelation of silica has large pores, and the porous material permeates the catalyst material of any size. For this reason, the catalyst material cannot be converted in a size selective manner.

  Therefore, the present invention solves the above-mentioned problems, and the object of the present invention is to have high mechanical and thermal stability without reducing the catalytic activity, and to make the catalytic substance size-selective. It is an object of the present invention to provide a nanocatalyst that can be converted into a catalyst and a production method thereof.

  As a result of intensive studies in view of the above, the present inventors have found that in a solution containing a metal ion that is a starting material of nanocatalyst particles and an organic compound that is a starting material of a porous carbon support having fine pores. By dispersing photocatalyst particles and irradiating the photocatalyst particles with excitation light under predetermined conditions, it has an ultrafine pore structure of 2 nm or less through a redox reaction and selectively passes through the target substance. It has been found that a catalyst in which metal nanoparticles are embedded in a porous carbon support can be produced. By the excitation light irradiation, electrons and holes are generated in the photocatalyst particles, and the electrons reduce metal ions contained in the solution to generate nanocatalyst particles. At the same time, the holes oxidize the organic compound and generate radicals thereof. The radical forms an organic polymer layer by the chain reaction, and a predetermined treatment is performed on the organic polymer layer to form a reticulated carbon support having an ultrafine microporous structure of 2 nm or less. Since the carbon support is formed through an ancestor organic polymer layer formed by radical reaction, an extremely large surface area can be obtained. Therefore, the active sites on the nanocatalyst particle surface are hardly reduced and the catalytic activity is not lowered. In addition, the nanocatalyst particles are embedded in a porous support made of carbon having a high affinity with the catalyst material in contact with the catalyst material to be catalyzed. High catalytic activity can be achieved by adsorption or concentration near the surface of the catalyst particles. Furthermore, since the aggregation of the nano catalyst particles can be prevented, the catalytic activity does not decrease even when used for a long time. In addition, since the micropores of the carbon support have a molecular sieving effect that allows selective passage of the catalyst material, size selective catalytic reaction can proceed on the nanocatalyst particles. Based on the above findings, the present inventors have completed the present invention.

  Therefore, the catalyst according to the present invention is a catalyst including a support having fine pores and catalyst particles, wherein the support includes carbon, and at least a part of the catalyst particles is buried in the support. It is characterized by that. A plurality of fine pores are connected to the surface of the catalyst particles and communicate with the outside of the porous support through each pore, so that the catalyst substance can be infiltrated, and the infiltrated catalyst substance is nano Contact with the catalyst particles is possible. In addition, since the nanocatalyst particles are dispersed and embedded in a porous carbon support having high mechanical strength, aggregation of the nanocatalyst particles can be prevented and the catalyst function can be maintained in a very high state for a long time. it can. In addition, since the fine pores of the carbon membrane have a molecular sieving effect that allows selective passage of the catalytic substance, a size selective catalytic reaction proceeds on the nano catalyst particles.

  The catalyst according to the present invention is characterized in that the support is a hollow body, and the catalyst particles are buried on the hollow side of the support.

  Moreover, in the catalyst according to the present invention, the diameter of the micropores is preferably 10 nm or less.

  Furthermore, in the catalyst according to the present invention, the catalyst particles preferably have a diameter of 0.5 nm to 10 nm.

  Furthermore, in the catalyst according to the present invention, it is preferable that the shape of the porous support is a hollow sphere, and the diameter thereof is 20 nm to 2 μm.

  In the catalyst according to the present invention, the catalyst particles may be platinum (Pt), palladium (Pd), iron (Fe), ruthenium (Ru), cobalt (Co), rhodium (Rh), iridium (Ir), nickel. It is preferably at least one selected from the group consisting of (Ni), gold (Au), copper (Cu), and silver (Ag).

  The catalyst production method according to the present invention is a catalyst production method for producing a catalyst comprising a support having fine pores and catalyst particles, wherein the support contains carbon, and at least of the catalyst particles. The method includes a burying step of burying a part of the support in the support. The burying step includes a step of providing an aqueous solution containing an organic compound, metal ions, and photocatalyst particles, and an organic polymer layer is generated from the organic compound, and the photocatalyst particles are generated to generate the catalyst particles from metal ions. And an irradiation step of irradiating the organic polymer layer with an excitation light, and a carbonization step of carbonizing the organic polymer layer. According to the method of the present invention, the formation of the porous carbon support and the formation of the nanocatalyst particles can be performed simultaneously, so that the process can be simplified.

  The catalyst preparation method according to the present invention is characterized in that the burying step includes a dissolving step of dissolving the photocatalyst particles.

Moreover, in the catalyst preparation method according to the present invention, the photocatalyst particles include titanium oxide (TiO ₂ ), strontium titanate (SrTiO ₃ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), niobium oxide (Nb ₂ ). O ₅ ), tantalum oxide (Ta ₂ O ₅ ), cadmium sulfide (CdS), zinc sulfide (ZnS), bismuth vanadate (BiVO ₄ ), alkali metal titanate, and alkali metal niobate It is preferable to consist of at least one selected.

  In the catalyst preparation method according to the present invention, the organic compound is selected from the group consisting of phenol, dihydroxylbenzene, hydroxylbenzenecarboxylic acid, dicarboxylbenzene, phthalate, cresol, naphthol, dihydroxylnaphthalene, and biphenol. It is preferable to contain at least one selected from the above.

Furthermore, in the catalyst preparation method according to the present invention, the metal ion is at least one selected from the group consisting of Pt ⁴⁺ , Pt ²⁺ , Pd ²⁺ , Rh ³⁺ , Ir ³⁺ , Au ³⁺ , Cu ²⁺ , and Ag ^+. It is preferable to contain.

  Moreover, in the catalyst preparation method according to the present invention, the temperature at which the organic polymer layer is carbonized is preferably 500 ° C to 1000 ° C.

  Furthermore, in the catalyst preparation method according to the present invention, the solvent capable of dissolving the photocatalyst particles is selected from the group consisting of hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, ammonia, and hydrogen peroxide. It is preferable to include at least one selected.

  Further, another catalyst preparation method according to the present invention includes a step of providing a structure in which the burying step includes a base material and a porous inorganic oxide layer formed on a surface of the base material, and the porous inorganic material. A first forming step of forming a first organic polymer layer in a lower layer portion of the oxide layer, an insertion step of inserting the catalyst particles into at least a part of pores of the porous inorganic oxide layer, and the first organic A second forming step of forming a second organic polymer layer on an upper layer of the polymer layer; and carbonizing the first organic polymer layer and the second organic polymer layer to produce the support. And carbonization step. In this method, since a porous inorganic oxide formed by gelation is used as a template, pores having a relatively large pore diameter can be obtained. However, since the organic polymer layer is carbonized, ultrafine micropores can also be obtained. Can do.

  Further, another catalyst preparation method according to the present invention is characterized in that the burying step includes a dissolving step of dissolving the base material and the porous inorganic oxide layer.

  In another catalyst preparation method according to the present invention, the porous inorganic oxide layer is preferably filled with an organic compound by an impregnation method, a chemical vapor deposition method, or a hydrothermal treatment method.

  Further, in the porous layer forming step of another catalyst preparation method according to the present invention, the porous inorganic oxide layer is made of metal alkoxide, alkali metal silicate, metal acetyl acetate, metal nitrate, or metal hydrochloride. It is preferably formed by hydrolysis / dehydration condensation.

  Further, in the porous layer forming step of another catalyst preparation method according to the present invention, the porous inorganic oxide layer is replaced with alkoxysilane, alkyl group-containing silicon alkoxide, sodium silicate, titanium alkoxide, titanium chloride, aluminum. Preferably, at least one selected from the group consisting of alkoxide, magnesium alkoxide, lanthanum alkoxide, lanthanum nitrate, cerium alkoxide, and cerium nitrate is gelled and heat-treated.

  Further, in another catalyst preparation method according to the present invention, the base material is at least one oxide selected from the group consisting of silica, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, lanthanum oxide, and cerium oxide. It is preferable to include.

  Further, in another catalyst preparation method according to the present invention, the porous inorganic oxide layer is at least one selected from the group consisting of silica, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, lanthanum oxide, and cerium oxide. It is preferable that the oxide of this is included.

  In another catalyst preparation method according to the present invention, the carbon-containing organic compound is at least one selected from the group consisting of glucose, sucrose, furfuryl alcohol, pyrrole, mesophase pitch, ethylene gas, and an aromatic organic compound. Preferably it is a seed.

  Moreover, in another catalyst preparation method according to the present invention, it is preferable that a temperature at which the first and second organic polymer layers are carbonized is 500 to 1000 ° C.

  In another catalyst preparation method according to the present invention, the solvent is at least selected from the group consisting of hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, ammonia, and hydrogen peroxide. One type is preferable.

  Furthermore, another catalyst preparation method according to the present invention includes a step of providing a structure in which the burying step includes a base material and a first organic polymer layer formed on a surface of the base material, A step of providing the catalyst particles on one organic polymer layer, a second forming step of forming a second organic polymer layer on the first organic polymer layer and the catalyst particles, and the support. In order to produce | generate, the carbonization process of carbonizing the said 1st organic polymer layer and the said 2nd organic polymer layer is included, It is characterized by the above-mentioned. Even in this method, since the organic polymer layer is carbonized, ultrafine micropores can be obtained.

  Yet another catalyst preparation method according to the present invention is characterized in that the burying step includes a dissolving step of dissolving the substrate.

  Further, in still another catalyst preparation method according to the present invention, the substrate is made of at least one selected from the group consisting of silica, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, lanthanum oxide, and cerium oxide. It is preferable.

  Further, in still another catalyst preparation method according to the present invention, the carbon-containing organic compound is at least selected from the group consisting of glucose, sucrose, furfuryl alcohol, pyrrole, mesophase pitch, ethylene gas, and an aromatic organic compound. One type is preferable.

  Further, in still another catalyst preparation method according to the present invention, the nanocatalyst particles are at least selected from the group consisting of Pt, Pd, Fe, Ru, Co, Rh, Ir, Ni, Au, Cu, and Ag. Preferably it comprises one.

  In still another catalyst preparation method according to the present invention, the solvent is selected from the group consisting of hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, ammonia, and hydrogen peroxide. It is preferable that there is at least one.

In the method for producing a catalyst according to the present invention, a network-like porous carbon support having fine pores developed by a radical chain reaction by photocatalysis can be formed. Therefore, the catalyst material can be infiltrated into the porous support, and the infiltrated catalyst material can be in contact with the nanocatalyst particles. Therefore, the active sites of the nanocatalyst particles are not reduced and the catalytic activity is not lowered. Further, since the nanocatalyst particles are dispersed and embedded in the porous support, aggregation of the nanocatalyst particles can be prevented, and the catalyst function can be maintained in a very high state for a long time. Therefore, according to the present invention, it is possible to provide a catalyst preparation method that has high mechanical and thermal stability without reducing the catalytic activity, and that can selectively convert the catalyst material.
Further, in the nanoparticle catalyst according to the present invention, since the nanocatalyst particles are dispersed on the network-like porous carbon support having fine pores developed as described above, the active sites of the nanocatalyst particles are reduced. The catalytic activity does not decrease. Moreover, aggregation of the nano catalyst particles can be prevented. Therefore, even if it is used for a long time, the catalytic activity can be kept high. Furthermore, since the molecular sieve effect of allowing the catalytic material to permeate into the porous support in a size-selective manner can be provided by the pore size of the porous support, a size-selective catalytic reaction is allowed to proceed on the nanocatalyst particles. be able to. Moreover, since at least a part of the catalyst particles is embedded in the support, the active sites of the embedded part of the catalyst particles are not reduced. Therefore, according to the present invention, it is possible to provide a nanocatalyst that has high mechanical and thermal stability without reducing the catalytic activity, and that can selectively convert the catalyst material.

Also in the second method, the nanocatalyst particles can be dispersed in a state of being separated in the porous support body made of carbon, so that a decrease in activity due to aggregation can be prevented. Furthermore, since the molecular sieve effect of allowing the catalytic material to permeate into the porous support in a size-selective manner can be provided by the pore size of the porous support, a size-selective catalytic reaction is allowed to proceed on the nanocatalyst particles. be able to.
Further, in the third method, since the nano catalyst particles can be dispersed in the porous support body made of carbon in the same manner as described above, it is possible to prevent a decrease in activity due to aggregation. Furthermore, since the molecular sieve effect of allowing the catalytic material to permeate into the porous support in a size-selective manner can be provided by the pore size of the porous support, a size-selective catalytic reaction is allowed to proceed on the nanocatalyst particles. be able to.

  Hereinafter, a nanoparticle catalyst according to an embodiment of the present invention will be described with reference to the drawings. Here, the case where the porous support body which consists of carbon is a substantially spherical hollow body is demonstrated. However, the following are examples of the present invention, and the present invention is not limited to these. Here, throughout this specification, the same member has the same reference number.

(Embodiment 1)
As shown in FIG. 1, the catalyst according to the first embodiment (a nanoparticle catalyst embedded in a porous carbon support) is composed of nanocatalyst particles and a porous carbon support in which the nanocatalyst particles are embedded. It consists of the body. Hereinafter, each configuration of the nanoparticle catalyst will be described in detail.

(Porous carbon support)
The porous carbon support 1 according to the present invention is a network-like support having developed micropores, and communicates with the support through the micropores. On the porous carbon support 1, nano catalyst particles 2 are dispersed, and a catalytic material that can be catalyzed penetrates from the network structure and comes into contact with the nano catalyst particles 2 through micropores (micropores). To do. The surface area of the porous carbon support 1 ^is preferably 300m ² / g~2000m 2 / ^g, still more preferably 1000m ² / g~2000m 2 / g. When the surface area is in such a range, the porous carbon support is in a very rough state, and the catalyst material can easily pass through the support. Therefore, although the nano catalyst particles are buried in contact with the porous carbon support, the catalytic activity does not decrease.
In addition, the porous carbon support needs to include fine pores having a diameter of 10 nm or less, more preferably 1 nm or less. By including an infinite number of such openings, the material to be catalyzed penetrates into the photocatalyst particles and can be contacted. Therefore, the catalytic activity does not decrease.
The porous carbon support may have any shape as long as it does not affect the catalytic action. Examples of the shape include a columnar shape, a spherical shape, a conical shape, a plate shape, a hollow cylindrical shape, a hollow spherical shape, a hollow conical shape, and a rod shape. From the viewpoint of production, the shape of the porous carbon support is preferably a hollow sphere.
Moreover, it is preferable that the film thickness of a porous carbon support body is 2 nm-200 nm, More preferably, it is 2 nm-50 nm. If the film thickness of the porous carbon support is within such a range, both sufficient mechanical resistance and efficient diffusion of the catalyst substance to the nanocatalyst particles embedded in the porous carbon support can be achieved. be able to.
The porous carbon support according to the present invention may be composed of any material, but is preferably composed of carbon. Carbon is hydrophobic and has high affinity with organic matter. Therefore, it is easy to adsorb and concentrate the catalyst material, and the catalyst material is effectively supplied to the nanocatalyst particles. Moreover, since carbon is generally electron-excess, oxidation of the metal nanoparticles in the porous carbon support can be suppressed.

(Nano catalyst particles)
The nanocatalyst particles according to the present invention promote the reaction with respect to a catalytic material that can be catalyzed. Accordingly, any nano catalyst particles may be used as long as they can exhibit the catalytic action. Examples of nano catalyst particle materials include platinum (Pt), palladium (Pd), iron (Fe), ruthenium (Ru), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), Gold (Au), copper (Cu), or silver (Ag) can be used. Two or more of these metals may be included. The nanocatalyst particles may be in various forms such as a simple substance, an alloy, or an inorganic salt.

  The diameter of the nanocatalyst particles is set to a size that can exert a catalytic action, but is preferably 0.5 nm to 20 nm, and more preferably 0.5 nm to 5 nm.

(Embodiment 2)
Next, the method for producing a catalyst according to the second embodiment will be described. The catalyst preparation method according to the present invention is a method of preparing a catalyst comprising a porous carbon support and nano catalyst particles dispersed and embedded on the surface or inside of the porous carbon support, A step of mixing photocatalyst particles with an aqueous solution containing an organic compound that is a starting material of a porous carbon support and a metal ion that is a starting material of the nanocatalyst particles; To form an organic polymer layer on at least a part of the photocatalyst particles, and to form the nanocatalyst particles in a state of being dispersed and embedded in the organic polymer layer, and carbonizing the organic polymer layer. And a step of forming a porous support made of carbon, and a step of dissolving the photocatalyst particles by immersing the nanocatalyst in a solvent capable of dissolving the photocatalyst particles. As described above, the method involves dispersing photocatalyst particles in a solution containing metal ions that are starting materials of nanocatalyst particles and organic compounds that are starting materials of a porous carbon support, and the photocatalyst particles are formed under predetermined conditions. By irradiating with excitation light, a composite in which nano-catalyst particles are separated and dispersed on a porous carbon support through an oxidation-reduction reaction can be produced. FIG. 4 is a process diagram of the manufacturing method. The nanocatalyst preparation method according to the second embodiment will be described in detail according to the process chart.

1) Preparation of photocatalyst particles First, particles containing a photocatalyst are prepared. A bulk material may be made ultrafine or may be prepared by a precipitation method or the like. The size of the photocatalyst particles is not particularly limited, but is preferably 20 nm to 2 μm, more preferably 20 nm to 500 m.

2) Preparation of Mixed Solution of Organic Compound and Metal Ion Subsequently, metal ions M ^{n +} which are starting materials of metals (for example, Pt, Pd, Rh, Ir, Au, Cu, Ag, etc.) that become nanocatalyst particles, and The organic compound that will constitute the porous carbon support is mixed into the solution and stirred sufficiently to prepare a mixed solution thereof. Examples of the metal ion M ^{n +} include Pt ⁴⁺ , Pt ²⁺ , Pd ²⁺ , Rh ³⁺ , Ir ³⁺ , Au ³⁺ , Cu ²⁺ , or Ag ⁺ . Examples of the organic compound that constitutes the porous carbon support include phenol, dihydroxylbenzene (examples of dihydroxybenzene include catechol, resorcinol, hydroquinone, etc.), hydroxylbenzenecarboxylic acid (hydroxybenzenecarboxylic acid). Examples of the acid include salicylic acid, 4-hydroxylbenzene carboxylic acid, etc.), dicarboxyl benzene (the dicarboxyl benzene includes phthalic acid, terephthalic acid, isophthalic acid, etc.), phthalate, cresol, Use naphthol, dihydroxyl naphthalene, or biphenol.

3) Mixing Subsequently, the photocatalyst particles prepared in 1) are added to the mixed solution prepared in 2) and stirred.

4) Excitation light irradiation Subsequently, excitation light is irradiated to excite the photocatalyst particles dispersed in the mixed solution (FIG. 4A). As a result, electrons e ⁻ and holes h ⁺ are generated in the photocatalyst particles. The electrons reduce the metal ions M ^{n +} contained in the solution prepared in 2) to generate nano catalyst particles on the surface of the photo catalyst particles. Further, the holes h ⁺ oxidize the organic compound O contained in the solution to generate countless radicals. A specific radical reacts infinitely with an organic compound or another radical, and an organic polymer layer containing carbon is formed on the surface of the photocatalyst particles (FIG. 4). For example, when phenol is used as the organic compound, specifically, as shown in FIG. 5, a radical species in which a phenol molecule is oxidized by h ⁺ reacts with another phenol molecule in a chain manner to form a crosslinked structure. Will be formed. The crosslinked structure is considered to contribute to the expression of fine pores of 2 nm or less in the finally formed porous carbon support.
When both the reduction reaction of the metal ion and the oxidation reaction of the organic compound proceed to some extent, the catalyst particles are embedded in the organic polymer layer, and these reactions do not proceed and stop at some point.
The nanocatalyst particles are generated near the surface of the photocatalyst particles, and at the same time, the organic polymer layer grows so as to cover the nanocatalyst particles. Therefore, the nanocatalyst particles are formed relatively concentrated on the inner wall side inside the organic polymer layer (FIG. 4B). With such a configuration, the nanocatalyst particles of the nanoparticle catalyst embedded in the finally obtained porous carbon support are separated from the outside by the porous carbon support. This is preferable because a size selective catalytic reaction can proceed by the molecular sieving effect due to the pore size.

5) Carbonization treatment The particles obtained as described above are subjected to carbonization treatment at 500 ° C to 1000 ° C, preferably 600 ° C to 900 ° C. Thereby, the organic polymer layer is carbonized to form a network-like porous carbon shell (porous carbon support) (FIG. 4C).

6) Dissolving and removing photocatalyst particles Subsequently, the nanocatalyst catalyst (p-C / nano) embedded in a porous carbon support was dissolved and removed with an inorganic or organic solution capable of dissolving the photocatalyst particles. Catalyst particles / C) (FIG. 4D). Examples of the solution capable of dissolving such photocatalyst particles include a solution containing hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, ammonia, and hydrogen peroxide. The photocatalyst particles do not necessarily have to be dissolved and discharged, and the photocatalyst particles may remain in the porous carbon support. However, in order to efficiently diffuse the target substance, all or part of the photocatalyst particles may be left. More preferably, it is discharged. Examples of the photocatalyst include titanium oxide (TiO ₂ ), strontium titanate (SrTiO ₃ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), niobium oxide (Nb ₂ O ₅ ), and tantalum oxide (Ta ₂ O _5). ), Cadmium sulfide (CdS), zinc sulfide (ZnS), bismuth vanadate (BiVO ₄ ), alkali metal titanate, and alkali metal niobate. Moreover, you may combine at least 1 or more types among these. In the present invention, it is preferable to use titanium oxide (TiO ₂ ) or zinc oxide (ZnO) as the photocatalyst. Here, the titanium oxide (TiO ₂ ) may be any type of anatase type, brookite type, rutile type, etc., and may be a mixed crystal type of these, but fine particles are easy. Therefore, the anatase type is more preferable.

(Embodiment 3)
Next, a method for producing a nanoparticle catalyst embedded in a porous carbon support according to Embodiment 3 will be described. The method for producing a nanoparticle catalyst embedded in a porous carbon support according to Embodiment 3 is produced without using photocatalytic action, whereas the production method according to Embodiment 2 is produced using photocatalytic action. In this respect, the third embodiment is different from the second embodiment. FIG. 6 is a process diagram of the manufacturing method.

Preparation of inorganic oxide particles First, inorganic oxide particles as a substrate are prepared. The inorganic oxide particles may be bulky ultrafine or may be produced by a precipitation method or the like. The size of the particles is not particularly limited, but is preferably 20 nm to 2 μm, more preferably 20 nm to 500 m. Here, when the inorganic oxide particles are silica, spherical silica particles having different sizes can be produced by hydrolysis and dehydration condensation of alkoxysilanes such as tetraethoxysilane (TEOS) under various conditions. Examples of the alkoxysilane include tetramethoxysilane (TMOS) and tetrabutoxysilane (TBOS) in addition to TEOS. Further, sodium silicate may be used as a raw material instead of alkoxysilane. Examples of the base material other than silica include titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, lanthanum oxide, and cerium oxide.

2) Preparation of base material (core) / porous inorganic oxide layer (shell) Core / shell particles in which the surface of the base material particle prepared in 1) is coated with a porous inorganic oxide layer are prepared. Base particles and an interface such as an alkylammonium salt (an example of an alkylammonium salt is cetyltrimethylammonium bromide) or a triblock copolymer (an example of a triblock copolymer is ethylene oxide-propylene oxide-ethylene oxide). Made by gelling and heat-treating the above alkoxysilane, sodium silicate, titanium alkoxide, titanium chloride, aluminum alkoxide, magnesium alkoxide, lanthanum alkoxide, lanthanum nitrate, cerium alkoxide, and cerium nitrate in a solution containing an activator. .

  Here, when the base material (core) is silica particles and the porous inorganic oxide layer (shell) is silica, the silica particles as the base material are, for example, alkoxysilane such as TEOS and octadecyltrimethoxysilane ( ODTS) and the like, suspended in a solution containing silicon alkoxide containing one or more alkyl groups, and hydrolyzing and dehydrating condensation reaction of these silicon alkoxides to form a silica particle substrate with a silica layer containing alkyl groups. After coating, the silica particles (core) / porous silica layer (shell) can also be obtained by heat-treating this to decompose and remove alkyl groups.

Here, two or more alkyl groups contained in the silicon alkoxide may be present in the molecule, and may be linear or branched. Moreover, what contains a functional group etc. in the terminal and intermediate | middle of an alkyl group may be sufficient. Typical examples of linear or branched alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isoamyl, and hexyl groups. , An octyl group, an octadecylyl group, and the like, and representative examples of functional groups included include a phenyl group, an amino group, a hydroxyl group, a fluoro group, and a thiol group.
Specific examples of the alkoxysilane include tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetrabutoxysilane (TBOS) and the like.

When a silicon alkoxide containing a functional group such as an alkyl group is used, a hydrolysis reaction and a dehydration condensation reaction proceed with the functional group remaining. Examples of hydrolysis reaction and dehydration condensation reaction of ODTS (octadecyltrimethoxysilane, Si (OCH ₃ ) ₃ (C ₁₈ H ₃₇ )) are shown below.
1. Hydrolysis reaction Si (OCH ₃ ) ₃ (C ₁₈ H ₃₇ ) + 3H ₂ O → Si (OH) ₃ (C ₁₈ H ₃₇ ) + 3CH ₃ OH
2. Dehydration condensation reaction Si (OH) ₃ (C ₁₈ H ₃₇ ) + Si (OH) ₃ (C ₁₈ H ₃₇ ) → (C ₁₈ H ₃₇ ) (OH) ₂ Si—O—Si (OH) ₂ (C ₁₈ H ₃₇ ) + H ₂ O
In the SiO ₂ containing the octadecyl group (C ₁₈ H ₃₇ —) formed by the reaction, the portion of the octadecyl group is decomposed and removed by heating, and this portion becomes the pores of the porous layer. Thereby, a porous silica layer is formed (FIG. 6C).

3) Filling the organic polymer layer The organic polymer layer is filled in the porous portion of the particle having the porous inorganic oxide layer outside the base material core particle. The filling method includes an impregnation method in which particles having a porous inorganic oxide layer are added to a carbon-containing organic compound solution and evaporated to dryness, a chemical vapor deposition method in which vapor of the carbon-containing organic compound is deposited, and a carbon-containing organic compound There is a hydrothermal treatment method in which a hydrothermal treatment is performed in an aqueous solution for filling. Here, examples of the carbon-containing organic compound include glucose, sucrose, furfuryl alcohol, pyrrole, mesophase pitch, ethylene gas, and an aromatic organic compound. Hereinafter, a method of forming an organic polymer layer by a hydrothermal treatment method in a porous portion of a particle having a porous silica layer outside the silica particle will be described.

Particles having a porous silica layer on the outside of the silica particles described above were stirred at room temperature in methanol containing aminoethylaminopropyltriethoxysilane (AEAP), and then the solution portion was removed and vacuum-dried to obtain A-SiO _2. @ M-SiO ₂ is produced (FIG. 6D). Here, the _{A-SiO 2 @ m-SiO} 2, means outside particles having a modified porous silica layer porous silica layer surface amino groups of the particles having a silica particle.
A-SiO ₂ @ m-SiO ₂ is hydrothermally treated in an aqueous solution of a carbon-containing organic compound such as glucose. The carbon-containing organic compound solution enters the pores of the porous silica layer, and a first organic polymer layer is formed in the lower layer of the porous silica layer (FIG. 6E).

4) Preparation of nanoparticle catalyst (mC / nanocatalyst particle / C) embedded in a porous carbon support Substrate (core) / porous inorganic material filled with the obtained first organic polymer layer The oxide layer (shell) particles are dispersed in a solution containing the starting material of the nanocatalyst particles, for example, an aqueous solution of chloroplatinic acid (H ₂ PtCl ₆ ), and then evaporated to dryness. If necessary, this powder is further heat-treated in a hydrogen stream. Thereby, the precursor oxide of nano catalyst particles or nano catalyst particles can be arranged on the first organic polymer layer formed under the porous inorganic oxide layer (FIG. 6F). ). As such nanocatalyst particle starting materials, chloroplatinic acid (H ₂ PtCl ₆ ), tetraammineplatinum chloride ([Pt (NH ₃ ) ₄ ] Cl ₂ ), palladium chloride (PdCl ₂ ), palladium nitrate (Pd (NO ₃ )) ₂ ), sodium palladium chloride (PdCl ₂ .2NaCl), palladium acetate ((CH ₃ COO) ₂ Pd), iron chloride (FeCl ₃ ), iron nitrate (Fe (NO ₃ ) ₃ ), ruthenium chloride (RuCl ₃ ) , Dodecacarbonylruthenium (Ru ₃ (CO) ₁₂ ), cobalt chloride (CoCl ₂ ), cobalt nitrate (Co (NO ₃ ) ₂ ), cobalt citrate (Co ₃ (C ₆ H ₅ O ₇ ) ₂ ), rhodium chloride (RhCl _3), rhodium nitrate _{(Rh (NO 3) 3)} , dodecacarbonyl rhodium _(Rh 4 _{(CO) 12} , Iridium chloride (IrCl _3), dodecacarbonyl iridium _{(Ir 4 (CO) 12)} , nickel chloride (NiCl _2), nickel nitrate _{(Ni (NO 3) 2)} , nickel acetate _{((CH 3 COO) 2 Ni} ), chloroauric acid (HAuCl _4), copper sulfate (CuSO _4), copper nitrate _{(Cu (NO 3) 2)} , copper acetate _{((CH 3 COO) 2 Cu} ), silver nitrate (AgNO _3), silver sulfate _(Ag 2 SO ₄ ). The powder thus obtained is filled with the same organic polymer layer as described above, for example, hydrothermally treated again in an aqueous glucose solution to form a second organic polymer layer on the porous inorganic oxide layer. (FIG. 6 (g)). After carbonizing this by heat treatment at 500 to 1000 ° C. in a vacuum or in an inert gas (nitrogen, argon, etc.), the base particle located at the center and the porous inorganic oxide layer formed outside thereof are formed. Dissolve and remove. Depending on the substrate and the material forming the porous inorganic oxide layer, the solvent may be hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, ammonia, or hydrogen peroxide. Including. In the case of the above silica substrate (core) / porous silica (shell), it can be removed with an aqueous solution of hydrofluoric acid, an alkali solution such as sodium hydroxide or potassium hydroxide. If necessary, the treated sample is subjected to heat treatment at 100 to 500 ° C. under hydrogen to reduce the embedded metals to form nanocatalyst particles. Thereby, a nanoparticle catalyst (mC / nanocatalyst particle / C) embedded in a porous carbon support in which nanocatalyst particles are dispersed in a porous carbon support shell can be produced (FIG. 6). (H)).
According to the invention according to the third embodiment, as shown in FIG. 2, a porous carbon support having fine pores, and nano catalyst particles dispersed and embedded in the surface or inside of the porous carbon support. Can be prepared.

(Embodiment 4)
Next, a method for producing a catalyst according to Embodiment 4 will be described. FIG. 7 is a process diagram of the manufacturing method.

Preparation of inorganic oxide particles First, inorganic oxide particles as a substrate are prepared. The inorganic oxide particles may be bulky ultrafine or may be produced by a precipitation method or the like. The size of the particles is not particularly limited, but is preferably 20 nm to 2 μm, more preferably 20 nm to 500 m. Here, when the inorganic oxide particles are silica, spherical silica particles having different sizes can be produced by hydrolysis and dehydration condensation of alkoxysilanes such as tetraethoxysilane (TEOS) under various conditions. Examples of the alkoxysilane include tetramethoxysilane (TMOS) and tetrabutoxysilane (TBOS) in addition to TEOS. Further, sodium silicate may be used as a raw material instead of alkoxysilane. Examples of the base material other than silica include titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide, lanthanum oxide, and cerium oxide.

2) Coating with organic polymer layer An organic polymer layer is coated on the outside of the above-mentioned substrate particles. The coating method includes an impregnation method in which base particles are added to a carbon-containing organic compound solution and evaporated to dryness, a chemical vapor deposition method in which vapor of the carbon-containing organic compound is deposited, and hydrothermal treatment in an aqueous carbon-containing organic compound solution. There is a hydrothermal treatment method in which the filling is performed. Here, examples of the carbon-containing organic compound include glucose, sucrose, furfuryl alcohol, pyrrole, mesophase pitch, ethylene gas, and an aromatic organic compound. Hereinafter, a method of coating silica particles with an organic polymer layer by a hydrothermal treatment method will be described.

After the silica particles as the base material were stirred at room temperature in methanol containing aminoethylaminopropyltriethoxysilane (AEAP), the solution portion was removed and vacuum-dried to produce A-SiO ₂ (FIG. 7B). )). Here, the A-SiO _2, means particles having a modified amino groups on the surface of the silica particles.
A-SiO ₂ is hydrothermally treated in an aqueous glucose solution. The carbon-containing organic compound solution forms a first organic polymer layer on the silica surface (FIG. 7C).

3) Preparation of nanoparticle catalyst (C / nanocatalyst particle / C) embedded in a porous carbon support The base material particle coated with the obtained first organic polymer layer was used as a starting material for the nanocatalyst particle. After being dispersed in a solution containing, for example, a H ₂ PtCl ₆ aqueous solution, it is evaporated to dryness. If necessary, this powder is further heat-treated in a hydrogen stream. Thereby, the precursor oxide of nano catalyst particles or nano catalyst particles can be disposed on the first organic polymer layer formed under the porous inorganic oxide layer (FIG. 7D). ). As the nanocatalyst particle starting materials, as described above, chloroplatinic acid (H ₂ PtCl ₆ ), tetraammineplatinum chloride ([Pt (NH ₃ ) ₄ ] Cl ₂ ), palladium chloride (PdCl ₂ ), palladium nitrate (Pd) (NO ₃ ) ₂ ), sodium palladium chloride (PdCl ₂ .2NaCl), palladium acetate ((CH ₃ COO) ₂ Pd), iron chloride (FeCl ₃ ), iron nitrate (Fe (NO ₃ ) ₃ ), ruthenium chloride ( RuCl ₃ ), dodecacarbonyl ruthenium (Ru ₃ (CO) ₁₂ ), cobalt chloride (CoCl ₂ ), cobalt nitrate (Co (NO ₃ ) ₂ ), cobalt citrate (Co ₃ (C ₆ H ₅ O ₇ ) ₂ ) , rhodium chloride (RhCl _3), rhodium nitrate _{(Rh (NO 3) 3)} , dodecacarbonyl rhodium _(Rh 4 (C ) _12), iridium chloride (IrCl _3), dodecacarbonyl iridium _(Ir 4 _{(CO) 12),} nickel chloride (NiCl _2), nickel nitrate _{(Ni (NO 3) 2)} , nickel acetate _((CH 3 _{COO) 2} Ni), chloroauric acid (HAuCl _4), copper sulfate (CuSO _4), copper nitrate _{(Cu (NO 3) 2)} , copper acetate _{((CH 3 COO) 2 Cu} ), silver nitrate (AgNO _3), silver sulfate ( Ag ₂ SO ₄ ). The powder thus obtained is filled with the same organic polymer layer as described above, for example, hydrothermally treated again in an aqueous glucose solution to form a second organic polymer layer on the first organic polymer layer. (FIG. 7 (e)). This is carbonized by heat treatment at 500 to 1000 ° C. in a vacuum or in an inert gas (nitrogen, argon, etc.), and then the substrate particles located at the center are dissolved and removed. Although it differs depending on the material forming the base material and the porous inorganic oxide layer, the solvent may be hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, ammonia, and hydrogen peroxide as described above. Things that include either are raised. In the case of the above silica substrate (core) / porous silica (shell), it can be removed with an aqueous solution of hydrofluoric acid, an alkali solution such as sodium hydroxide or potassium hydroxide. If necessary, the treated sample is subjected to heat treatment at 100 to 500 ° C. under hydrogen to reduce the embedded metals to form nanocatalyst particles. This makes it possible to produce a nanoparticle-based catalyst (C / metal nanoparticle / C) embedded in a porous carbon support in which nanocatalyst particles are dispersed in a porous carbon support shell (FIG. 7 (f )).
According to the invention of Embodiment 3, as shown in FIG. 3, a porous carbon support having fine pores, and nano catalyst particles dispersed and embedded in the surface or inside of the porous carbon support. Can be prepared.

(Separation / recovery method)
The nanoparticle catalyst embedded in the porous carbon support according to the present invention can be easily separated from the reaction solution by filtering with a filter paper or the like after completion of the catalytic reaction. Alternatively, the reaction solution may be separated by sedimentation by centrifugation. Thereafter, the dried and recovered catalyst can be reused as it is, or can be reused by performing an activation treatment as necessary. In addition, when the catalyst is discarded, even if nano catalyst particles use expensive or rare elements, the carbon content is decomposed by heat treatment. Since it can be removed, the elements of the nano catalyst particles can be easily recovered.

A catalyst was prepared by using the burying process according to claim 4.
I) Preparation of nanoparticle catalyst (pC / nanocatalyst particle / C) embedded in a porous carbon support Preparation of mixed solution First, TiO ₂ (Ishihara Sangyo ST21 or Ishihara Sangyo ST41) or ZnO 500 mg, H ₂ PtCl ₆ 2.6-26 μmol (0.1-1.0 wt%), phenol 200 mg (2.1 mmol) and water It was dispersed in a mixed solution consisting of 400 cm ³ .

2. Excitation light irradiation A mercury lamp is irradiated to the mixed solution under an argon atmosphere (irradiation light wavelength: 290 nm or more) to form a phenol resin on the TiO ₂ surface and to disperse Pt _nanocatalyst particles (Pt _NCP ) in the phenol resin. I let you.

3. Carbonization of polymer The particles were collected and calcined at 700 ° C. for 6 hours in vacuum or in an inert gas (nitrogen, argon, etc.). As a result, the layer made of the phenol resin was carbonized to form a porous carbon layer.

4). Removal of photocatalyst particles The photocatalyst particles present at the center of the above-mentioned particles were removed by immersing them in a chemical solution. Here, a 50% hydrofluoric acid aqueous solution was used as the chemical solution when the particles present at the center were TiO ₂ , and concentrated hydrochloric acid (35%) was used as the chemical solution when the particles were ZnO. As a result, a nanoparticle catalyst ( _pC / _PtNcP / C) in which Pt _NCP was embedded in a porous carbon support could be produced. FIG. 8 is a TEM view of the catalyst, and FIG. 9 is a cross-sectional view of the catalyst. It can be seen that Pt _NCP is contained only in the porous carbon layer and is relatively concentrated on the inner wall side of the carbon layer.

In addition, when RhCl ₃ is used as a raw material for the metal nanoparticles instead of H ₂ PtCl ₆ in the above process, rhodium nano catalyst particles (Rh _NCP ) are embedded in the porous carbon support as shown in the TEM diagram of FIG. In addition, a nanoparticle-based catalyst (p-C / Rh _NCP / C) could be produced.

II) Evaluation of structure and catalyst function Subsequently, the following experiment was performed on pC / nanocatalyst particles / C obtained as described above.
1. Nitrogen adsorption measurement

The adsorption properties of p-C / Pt _NCP / C having a diameter of 20 nm were examined when TiO ₂ (Ishihara Sangyo ST21) was used as photocatalyst particles and H ₂ PtCl ₆ was used as the metal nanoparticle source. FIG. 11 shows a nitrogen adsorption isotherm and its α _s plot. In the isotherm, a rapid increase in the amount of adsorption was observed when the relative pressure (p / p ₀ ) was about 0.9 or less. The former indicates the presence of 20 nm pores corresponding to the diameter of the hollow part of p-C / Pt _NCP / C, and the latter suggests that finer pores are present in the carbon support part. As a result of analyzing the micropores by an α _s plot, it was confirmed that the carbon support had micropores of 2 nm or less (Table 1). Here, the α _s plot is a plot for analyzing micropores on the basis of a non-porous sample. When there are no pores in the measurement sample, the plot becomes a straight line. The plot deviates from a straight line at a value of α _s depending on the pore size. As shown in FIG. 11, in p-C / Pt _NCP / C, the α _s value is 0.5 or less, and a deviation from the straight line indicated as FS and CS is seen in the portion of 0.5-1.0, It represents that micropores of 1 nm or less and 1-2 nm exist, respectively.
Further, when the surface area was calculated from the isotherm, it was 1400 m ² g ⁻¹ , and it was confirmed that p-C / Pt _NCP / C has a very high surface area.

2. Catalytic activity test Subsequently, the catalytic activity of the above-described p-C / Pt _NCP / C was evaluated using a hydrogen reaction in the liquid phase of 1-hexene, 2-hexene, and cyclohexene. For the activity evaluation, 1.4 mg (Pt 0.1 μmol) of Pt 1.4 wt% of p-C / Pt _NCP / C obtained using TiO ₂ (Ishihara Sangyo ST21) as photocatalyst particles was used, and the same Pt was used. It compared with the general catalyst (Pt / AC) which made Pt particle | grains carry | support on the porous surface of the activated carbon (AC) containing quantity. The results are shown in Table 1. It was confirmed that p-C / Pt _NCP / C showed a very high conversion rate in any catalyst material. Moreover, even if the sample after the reaction was separated and recovered by centrifugation and reused, no decrease in activity was observed, and it was confirmed that the sample had good reusability. From the above, it was revealed that p-C / Pt _NCP / C has an excellent function as a solid catalyst.

Then, the catalyst was produced using the burial process concerning Claim 6.
I) Preparation of nanoparticle catalyst (mC / nanocatalyst particle / C) embedded in a porous carbon support Preparation of silica particle base material After adding 180.62 ml of ethanol, 64.818 ml of water, 4.520 ml of aqueous ammonia (28%), and 14.56 g of tetraethoxysilane (TEOS) to a 500 ml Erlenmeyer flask at 27 ° C. and 110 rpm. Shake for 2 hours. The solution was centrifuged to remove the supernatant, and the resulting white precipitate was washed with ethanol and then vacuum-dried at 110 ° C. for 3 hours to produce silica particles as a substrate.

2. Preparation of silica (core) / porous silica (shell) particles In a 100 ml Erlenmeyer flask: After adding 500 mg of the silica particles prepared in step 37, 37 ml of ethanol, and 5 ml of water, the silica was dispersed by irradiating ultrasonic waves with a homogenizer. To this solution, 1.125 ml of aqueous ammonia (28%), 3.215 g of TEOS, and 1.149 g of ODTS were added, and the mixture was shaken at 27 ° C. and 120 rpm for 2 hours. The solution was centrifuged to remove the supernatant, washed with ethanol, and vacuum dried at 110 ° C. for 3 hours. The obtained white powder was baked at 550 ° C. for 6 hours to form a porous silica layer having pores outside the silica particles.

3. Preparation of m-C / Pt _NCP / C 1.5 g of particles having a porous silica layer having pores outside the above silica particles were dispersed in 24 ml of methanol and 568 mg of AEAP, and then stirred for 1 hour. The solution was centrifuged to remove the supernatant, washed with ethanol, and then vacuum-dried at 110 ° C. for 3 hours to produce amino group-modified particles (A-SiO ₂ @ m-SiO ₂ ).
200 mg of the obtained A-SiO ₂ @ m-SiO ₂ was hydrothermally treated in a 0.36 M glucose aqueous solution, 200 mg of the obtained powder was added to the H ₂ PtCl ₆ aqueous solution, and ultrasonic waves were applied for 20 minutes. This solution was transferred to an evaporating dish and evaporated to dryness, and then vacuum dried. This powder was hydrothermally treated again in a 0.41 M aqueous glucose solution, vacuum baked at 900 ° C. for 1.5 hours, and treated with a 10 vol% hydrofluoric acid aqueous solution. The treated material was heated at 300 ° C. for 2 hours under hydrogen to reduce Pt.

II) Evaluation of structure and catalytic function TEM Observation FIG. 12 shows a TEM diagram of the sample obtained in the above-described step, and FIG. 13 shows a TEM diagram after heat-treating the sample in a vacuum at 900 ° C. It can be seen that there are hollow carbon particles in which Pt _NCP is highly dispersed in carbon, and there is no change in the size or distribution of Pt _NCP even after heat treatment. From this, it was confirmed that the obtained m-C / Pt _NCP / C has a structure in which Pt _NCP is embedded in a carbon support, and this has extremely high thermal stability.

2. Nitrogen adsorption measurement As a result of investigating the pore structure of the carbon support in m-C / Pt _NCP / C by nitrogen adsorption measurement, it was confirmed that the carbon support had 0.4-1.0 nm micropores and 3.0 nm It was confirmed that the porous body was developed with relatively large pores. Further, when the surface area was calculated by the BET method, it was 1600 m ² g ⁻¹ , and it was confirmed that m-C / Pt _NCP / C has a very high surface area.

3. Catalytic activity test Subsequently, the catalytic activity of the obtained m-C / Pt _NCP / C was evaluated using a hydrogen reaction in the liquid phase of 1-hexene, 4-phenyl-1-butene, and trans-stilbene. For the activity evaluation, 1 mg (Pt 0.26 μmol) of Pt 5 wt% was used, and a sample (Pt / C) in which Pt fine particles were simply supported on carbon particles of hollow carbon particles containing the same amount of Pt. ). The results are shown in Table 2. When the catalyst material was 1-hexene, m-C / Pt _NCP / C showed a high conversion rate comparable to Pt / C. On the other hand, in the hydrogenation reaction of 4-phenyl-1-butene and trans-stilbene, the activity of m-C / Pt _NCP / C is greatly reduced as compared to Pt / C, and especially in trans-stilbene, there is a significant decrease in activity. It was. This is because, in m-C / Pt _NCP / C, nano catalyst particles, Pt _NCP, are embedded in a porous carbon support, and therefore, due to the molecular sieving effect of the carbon support, It shows that the reaction of bulky catalyzed material showed molecular size selectivity to be suppressed. From the above, it was revealed that m-C / Pt _NCP / C has a function as an excellent solid catalyst that induces a selective reaction.

Then, the catalyst was produced using the burial process concerning Claim 8.
I) Preparation of nanoparticle-based catalyst (C / nanocatalyst particle / C) embedded in a porous carbon support Preparation of silica particles To a 500 ml Erlenmeyer flask were added ethanol 18.0.662 ml, water 64.818 ml, aqueous ammonia (28%) 4.520 ml, tetraethoxysilane (TEOS) 14.56 g, and then at 27 ° C. and 110 rpm for 2 hours. Shake it. The solution was centrifuged to remove the supernatant, and the resulting white precipitate was washed with ethanol and then vacuum-dried at 110 ° C. for 3 hours to produce silica particles as a substrate.

2. Preparation of C / Pt _NCP / C and C / Pd _NCP / C 1.5 g of particles having a porous silica layer having pores outside the above silica particles were dispersed in 24 ml of methanol and 568 mg of AEAP, and then stirred for 1 hour. I let you. The solution was centrifuged to remove the supernatant, washed with ethanol, and then vacuum-dried at 110 ° C. for 3 hours to produce amino group-modified particles (A-SiO ₂ @ m-SiO ₂ ).
200 mg of the obtained A-SiO ₂ @ m-SiO ₂ was hydrothermally treated in a 0.36 M aqueous glucose solution, and 200 mg of the obtained powder was added to an aqueous H ₂ PtCl ₆ solution or (CH ₃ COO) ₂ Pd acetone-ethanol. In addition to the (1: 1) solution, ultrasonic waves were applied for 20 minutes. This solution was transferred to an evaporating dish and evaporated to dryness, and then vacuum dried. This powder was hydrothermally treated again in a 0.41 M aqueous glucose solution, vacuum baked at 900 ° C. for 1.5 hours, and treated with a 10 vol% hydrofluoric acid aqueous solution. The treated material was heated at 300 ° C. for 2 hours under hydrogen to reduce Pt or Pd.

II) Evaluation of structure and catalytic function TEM observation and nitrogen adsorption measurement FIG. 14 shows a sample (C / Pt _NCP / C) obtained using H ₂ PtCl ₆ as a metal nanoparticle source, and FIG. 15 shows (CH ₃ COO) ₂ Pd obtained as a metal nanoparticle source. The TEM figure of the obtained sample (C / Pd _NCP / C) is shown. In both cases, hollow carbon particles in which metal nanoparticles were highly dispersed in carbon existed, and it was confirmed that these had a structure in which the metal nanoparticles were embedded in a carbon support.
Further, as a result of nitrogen adsorption measurement for C / Pt _NCP / C, it was found that the carbon support had micropores around 0.4-1.0 nm and had a surface area of 350 m ² g ^−1. It was. Thereby, it was confirmed that the nanoparticle catalyst embedded in the porous carbon support was able to be produced.

2. Catalytic Activity Test Subsequently, the catalytic activity of the obtained C / nanocatalyst particles / C was evaluated using a hydrogen reaction in the liquid phase of 1-hexene, 4-phenyl-1-butene, and trans-stilbene. For the activity evaluation, 1 mg (Pt 0.26 μmol) of Pt 5 wt% was used in the case of Pt, and 3 mg (Pd 1.4 μmol) of Pd 15 wt% was used in the case of Pd. Further, a sample (Pt / C or Pd / C) in which Pt or Pd fine particles were merely supported on carbon particles of hollow carbon particles containing similar amounts of Pt and Pd was prepared and used as a comparative sample. As shown in Table 3, the micropores are not sufficiently developed as compared with the above-mentioned p-C / Pt _NCP / C and m-C / Pt _NCP / C, so that the activity of any catalyst material is higher than that of Pt / C. Although it decreased, the molecular size selectivity for suppressing the reaction of the bulky catalyst substance was very excellent. Similar high molecular size selectivity was also observed in the hydrogenation reaction of olefins with C / Pd _NCP / C (Table 4). From these, it became clear that C / nanocatalyst particles / C is a solid catalyst that induces a highly selective reaction.

  The nanocatalyst and the method for producing the same according to the present invention can be suitably used in the fields of hydrogenation reaction process, fine chemical synthesis process, or fuel cell.

1 is a cross-sectional view of a porous support-nanoparticle catalyst according to the present invention. It is sectional drawing of the porous support body-nanoparticle-type catalyst of another form which concerns on this invention. It is sectional drawing of the porous support body-nanoparticle type | system | group catalyst of another form which concerns on this invention. It is the figure which showed the manufacturing process of the manufacturing method which concerns on Embodiment 2 of this invention. It is an example of the formation reaction of the organic polymer layer utilized with the manufacturing method which concerns on Embodiment 2 of this invention. It is the figure which showed the manufacturing process of the manufacturing method which concerns on Embodiment 3 of this invention. It is the figure which showed the manufacturing process of the manufacturing method which concerns on Embodiment 4 of this invention. It is a TEM figure of the porous support body-nanoparticle type | system | group catalyst containing the Pt nano catalyst particle produced by the manufacturing method which concerns on Embodiment 2 of this invention. It is sectional drawing of the porous support body-nanoparticle type | system | group catalyst produced with the manufacturing method which concerns on Embodiment 2 of this invention. It is a TEM figure of the porous support body-nanoparticle type | system | group catalyst containing the Rh nanocatalyst particle produced by the manufacturing method which concerns on Embodiment 2 of this invention. It is the figure which showed the analysis by the nitrogen adsorption isotherm of the porous support body-nanoparticle type | system | group catalyst produced with the manufacturing method which concerns on Embodiment 2 of this invention, and its (alpha) _s plot. It is a TEM figure of the porous support body-nanoparticle system catalyst containing Pt nanocatalyst particle produced by the manufacturing method concerning Embodiment 3 of the present invention. It is a TEM figure of a sample after carrying out vacuum heating at 900 ° C of a porous support-nanoparticle system catalyst containing Pt nanocatalyst particles produced by a manufacturing method concerning Embodiment 3 of the present invention. It is a TEM figure of the porous support body-nanoparticle type | system | group catalyst containing the Pt nanocatalyst particle produced by the manufacturing method which concerns on Embodiment 4 of this invention. It is a TEM figure of the porous support body-nanoparticle type | system | group catalyst containing the Pd nanocatalyst particle produced by the manufacturing method which concerns on Embodiment 4 of this invention.

Claims (3)

A catalyst-supporting structure for an olefin hydrogenation reaction , comprising a hollow support having fine pores and catalyst particles,
The support is made of carbon;
The catalyst particles are made of platinum, palladium, ruthenium, rhodium, iridium, gold, copper, one or metal nanoparticles having a particle diameter 0.5nm~20nm comprising two or more selected from the group consisting of silver,
The support is a layered hollow body,
The catalyst particles are at least partially, and dispersed inside of the support layer so that embedded in the layer of the support, and the diameter of the fine pores of the support is 10nm or less, the catalyst support structure. A method for producing a catalyst-supporting structure for producing a catalyst-supporting structure for a hydrogenation reaction of an olefin, comprising a hollow support having fine pores and catalyst particles,
The support is made of carbon and has a fine pore diameter of 10 nm or less,
The method is
Providing a structure comprising a substrate and a porous inorganic oxide layer formed on the surface of the substrate;
A first forming step of forming a first organic polymer layer in a lower layer portion of the porous inorganic oxide layer;
A particle size of 0.1 or more selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, gold, copper, and silver is contained in at least a part of the pores of the porous inorganic oxide layer. An insertion step of inserting catalyst particles composed of metal nanoparticles of 5 nm to 20 nm;
A second forming step of forming a second organic polymer layer on an upper layer of the first organic polymer layer;
A carbonization step of carbonizing the first organic polymer layer and the second organic polymer layer to produce the support;
A dissolution step of dissolving the substrate and the porous inorganic oxide layer;
A method for producing a catalyst-supporting structure comprising: A method for producing a catalyst-supporting structure for producing a catalyst-supporting structure for a hydrogenation reaction of an olefin, comprising a hollow support having fine pores and catalyst particles,
The support is made of carbon and has a fine pore diameter of 10 nm or less,
The method is
Providing a structure including a substrate and a first organic polymer layer formed on the surface of the substrate;
On the first organic polymer layer, a metal nanoparticle having a particle diameter of 0.5 nm to 20 nm including one or more selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, gold, copper, and silver. Providing catalyst particles comprising particles,
A second forming step of forming a second organic polymer layer on the first organic polymer layer and the catalyst particles;
To produce the support, a carbonization step of carbonizing the first organic polymer layer and said second organic polymeric layer,
A dissolution step of dissolving the substrate;
A method for producing a catalyst-supporting structure comprising: