JP5034264B2 - Oxide composite and method for producing the same - Google Patents

Description

  The present invention relates to an oxide composite and a method for producing the same, and more particularly to an oxide composite in which metal oxide fine particles are introduced into pores of an inorganic porous material and a method for producing the same.

Nanometer-sized oxide particles may exhibit different properties than bulk materials due to their extremely small size. In particular, magnetic nanoparticles exhibit unique electrical, magnetic, optical, and chemical properties, so applications for magnetic fluids, biomedical images, information recording, various oxidation catalysts, etc. are being studied. .
In order to prevent aggregation, the nanoparticles are usually used in a state of being introduced into an inert matrix (for example, silica porous material). The introduction of nanoparticles into the matrix also has the effect of stabilizing unstable phases that are difficult to synthesize.
For example, iron (III) oxide has polymorphs such as α-Fe ₂ O ₃ (hematite), γ-Fe ₂ O ₃ (maghemite), ε-Fe ₂ O ₃ , and β-Fe ₂ O _3. . Among these, ε-Fe ₂ O ₃ is known to exhibit an extremely large coercive force in the form of fine particles, but single-phase ε-Fe ₂ O ₃ is generally difficult to synthesize. On the other hand, when iron (III) oxide is introduced into the matrix, ε-Fe ₂ O ₃ can be generated by optimizing the introduction conditions.

The following methods are known as methods for introducing such nanoparticles.
For example, Non-Patent Document 1 discloses a 0.5 M iron nitrate (Fe (NO ₃ ) ₃ ) solution in pores of mesoporous silica (MCM-41, MCM-48) having a specific surface area of 1000 to 1300 m ² / g. A method for producing a mesoporous silica-iron oxide composite is disclosed, which is impregnated, dried, and calcined in air at 673 K for 6 hours. According to this document, a mesoporous silica-iron oxide complex having a Fe content of 5.3 to 7.8 wt% can be obtained by such a method, and a part (10 to 12 nm) of iron oxide is obtained. It is described that it is on the outer surface of the host structure and the other part (3 to 4 nm) is introduced into the mesopore.

Further, Non-Patent Document 2, the specific surface area 299~571m ² / g (average pore size: 14~4nm) an ethanol solution of silica iron nitrate in the pores of the _{(Fe (NO 3) 3 ·} 9H 2 O) A method for producing a mesoporous silica-iron oxide composite which is impregnated and dried and then heat-treated at 400 ° C. in air is disclosed. In this document, a composite in which γ-Fe ₂ O ₃ particles having an average particle diameter of 2.5 to 5.8 nm are uniformly dispersed in silica is obtained by such a method, and the average pore size of silica is obtained. It is described that the Fe ₂ O ₃ content decreases with decreasing.

In Non-Patent Document 3, iron nitrate is added to a solution of tetraethoxysilane: water: ethanol = 1: 6: 6 to form a wet gel, and the wet gel is dried and pulverized to form a powder. A method for producing a silica-iron oxide composite that is heat-treated at 300 to 1100 ° C. in the atmosphere is disclosed. In this document, a silica-iron oxide complex containing 13 to 43 wt% of ε-Fe ₂ O ₃ is obtained by such a method, and when the content of iron oxide exceeds 37 wt%, α- The point that Fe ₂ O ₃ is the main phase is described.

  Furthermore, Non-Patent Document 4 discloses that iron oxide nanoparticles extracted from a magnetic fluid are dispersed in toluene, and this is added to a solution containing isopropanol, ion-exchanged water and aqueous ammonia to be emulsified, and further tetraethoxylated. A method for producing a silica-iron oxide composite is disclosed in which silane is added to coat the emulsion particles with a silica shell. This document describes that submicron order monodispersed spherical silica containing magnetic iron oxide nanoparticles can be obtained by such a method.

Ralf Kohn et al., Micropor.Mesopor.Mater., 63 (2003) 236-137 C. Cannas et al., J. Non-Cryst. Solids, 345 & 346 (2004) 653-657 M. Popovici et al., Chem. Mater., 16 (2004) 5542-5548 Sang Hyuk Im et al., Chem. Phys. Lett., 401 (2005) 19-23

In order to apply a composite containing oxide nanoparticles to various applications, it is important that the content of the oxide particles can be arbitrarily controlled while maintaining the size of the oxide particles at a nanometer size. Among the various methods described above, the method using mesoporous silica is easy to maintain the size of the oxide particles at a nanometer size because the growth of the oxide particles is suppressed by the pore walls.
However, since the iron compound generally has a relatively low solubility in a solvent, the concentration of iron that can be introduced into the pores is limited. In addition, iron compounds with relatively high solubility, such as iron nitrate and iron chloride, have a low melting point, and when the solvent is evaporated by heating, the iron compound tends to go out of the pores due to its vapor pressure. May be deposited on the outer surface of the silica. Further, the smaller the pore diameter of the silica, the more difficult the solution enters the pores, so the iron oxide content decreases. Further, Non-Patent Documents 1 and 2 do not specify the magnetization curve of the obtained sample, and the magnetic characteristics such as saturation magnetization are unknown.

In addition, in order to apply such a complex to photonic crystals and drug delivery, the shape of the complex is also important, and the shape is preferably spherical monodisperse.
When the so-called “sol-gel process” disclosed in Non-Patent Document 3 is used, a complex containing a large amount of magnetic iron oxide can be synthesized. However, the shape of the powder obtained by this method is indefinite, and it is difficult to apply it to photonic crystals.
On the other hand, when the so-called “Stober method” disclosed in Non-Patent Document 4 is used, a monodispersed spherical composite can be synthesized. However, in this method, the iron oxide content is 0.5 wt%, and the saturation magnetization is as small as 0.37 emu / g (see Non-Patent Document 4, page 23, left column, lines 20 to 23).

The problem to be solved by the present invention is to provide an oxide composite in which a relatively large amount of oxide nanoparticles are introduced into the pores of an inorganic porous body and a method for producing the same.
Another problem to be solved by the present invention is that an oxide composite in which a relatively large amount of oxide nanoparticles are introduced into the pores of the inorganic porous body and the shape thereof is a monodisperse sphere, and It is in providing the manufacturing method.
Furthermore, another problem to be solved by the present invention is to provide an oxide composite containing oxide nanoparticles and having excellent magnetic properties and a method for producing the same.

In order to solve the above problems, the method for producing an oxide composite according to the present invention includes impregnating pores of an inorganic porous body with a first solution in which metallocene or a derivative thereof is dissolved in a first solvent that is polymerized by heating. 1 impregnation step, a polymerization step in which the porous body is heated to polymerize the first solvent, and the inorganic porous body is heat-treated at 400 ° C. or higher in an oxygen-containing atmosphere to thermally decompose the metallocene or a derivative thereof. e Bei a first heat treatment step to produce the first metal oxide by the size of the pores is summarized in that a larger size of the metallocene or a derivative thereof.
In this case, a second impregnation step of impregnating a second solution obtained by dissolving a metal compound in a second solvent into the pores of the oxide composite obtained in the first heat treatment step, and the oxide composite And a second heat treatment step of heating at 400 ° C. or higher in an oxygen-containing atmosphere to generate a second metal oxide in the oxide composite.
In addition, the oxide composite obtained in the first heat treatment step or the second heat treatment step is heat-treated at 400 ° C. or higher in an inert atmosphere or a reducing atmosphere, and the third metal oxide is formed in the oxide composite. A third heat treatment step to be generated may be further provided.
In addition, the oxide composite according to the present invention is obtained by such a method.

Metallocene or a derivative thereof has extremely high solubility in an organic solvent. Therefore, when the pores are impregnated with the first solution in which this is dissolved, a larger amount of metal element can be introduced into the pores than in the conventional method. In addition, when a material that is polymerized by heating is used as the first solvent and the first solvent is polymerized and then thermally decomposed, scattering of the metal element outside the pores can be suppressed. Furthermore, when a spherical monodispersed mesoporous material is used as the inorganic porous material, an oxide composite having a relatively high content of the first metal oxide nanoparticles and a spherical monodispersed material can be obtained.
Furthermore, when a metal compound is further introduced into the oxide composite containing the first metal oxide and heat treatment is performed under a predetermined condition, the first metal oxide and the metal compound react to form a second metal oxide. An oxide composite containing product nanoparticles is obtained. In addition, when an oxide complex including nanoparticles of the first metal oxide or the second metal oxide is heated in an inert atmosphere or a reducing atmosphere, the third metal from which part of the oxygen in the nanoparticles is removed An oxide composite containing oxide nanoparticles is obtained.

Hereinafter, an embodiment of the present invention will be described in detail.
The method for producing an oxide composite according to the first embodiment of the present invention includes a first impregnation step, a polymerization step, and a first heat treatment step. In addition, the oxide composite according to the first embodiment of the present invention is obtained by the method according to the present embodiment.

The first impregnation step is a step of impregnating the pores of the inorganic porous body with a first solution in which metallocene or a derivative thereof is dissolved in a first solvent that is polymerized by heating.
In the present invention, as the first solvent, one that is polymerized by heating (thermopolymerizable solvent) is used. In order to increase the amount of oxide introduced into the inorganic porous material, the first solvent is preferably one in which the solubility of metallocene or a derivative thereof is large. Specific examples of such a heat-polymerizable solvent include furfuryl alcohol, aniline, and styrene. Among these, furfuryl alcohol is particularly suitable as the first solvent because it is easily polymerized and can dissolve a large amount of a certain metallocene or a derivative thereof.

“Metalocene” refers to a metal molecule sandwiched between two cyclopentadiene molecules. The metal atom contained in the metallocene is not particularly limited, and an optimal one is selected according to the use of the oxide composite. For example, when the oxide composite according to the present invention is used as a magnetic material such as a ferrofluid, the metallocene is one containing Fe as a metal element (ferrocene), one containing Co (cobaltcene), or one containing Ni (Nickelocene) is preferred.
The metal element contained in the metallocene or derivative thereof may be different from or the same as the metal element contained in the inorganic porous body.

The “metallocene derivative” refers to a compound in which an organic functional group is bonded to cyclopentadiene constituting the metallocene. The organic functional group contained in the metallocene derivative is not particularly limited, and an optimum one is selected according to the type of the first solvent, the use of the oxide composite, and the like. In particular, when the type of the organic functional group is optimized, the solubility in the first solvent can be remarkably increased.
For example, in the case where furfuryl alcohol is used as the first solvent, in order to significantly improve the solubility in furfuryl alcohol, the metallocene derivative is bonded with an oxygen-containing organic functional group such as an aldehyde group or a hydroxypropyl group. Those are preferred.
For example, when styrene is used as the first solvent, the metallocene derivative is preferably bonded with a vinyl group in order to remarkably improve the solubility in styrene and copolymerize with styrene.

As a starting material, one or more metallocenes or derivatives thereof containing only one metal element may be used, or one or more metallocenes or derivatives thereof containing different metal elements may be used in combination. May be used. When a metallocene containing two or more metal elements or a derivative thereof is used as a starting material, for example, an oxide composite containing a magnetic double oxide such as CoFe ₂ O ₄ can be synthesized.

  The concentration of the metallocene or derivative thereof in the first solvent is not particularly limited, and an optimal concentration is selected according to the purpose. In general, the higher the concentration of metallocene or a derivative thereof, the more metallocene or a derivative thereof can be introduced into the pores of the inorganic porous body by a single impregnation treatment.

“Inorganic porous body” refers to a porous body made of an inorganic material having oxidation resistance.
The inorganic material which comprises an inorganic porous body should just have oxidation resistance of the grade which can maintain the shape in the 1st heat processing process (and 2nd heat processing process and 3rd heat processing process) mentioned later. As such an inorganic material,
(1) Oxides such as silica, alumina, titania, zirconia, aluminosilicate, titanosilicate,
(2) Phosphate compounds such as aluminum phosphate, zirconium phosphate, apatite,
and so on.
In particular, silica is inert to iron-based oxides containing Fe, Co and / or Ni, and has an unstable phase (for example, ε-Fe ₂ O ₃ ) that cannot be obtained by ordinary synthesis methods. Since it has the effect | action which stabilizes, it is suitable as an inorganic material which comprises an inorganic porous body.

  The magnitude | size of an inorganic porous body is not specifically limited, According to the objective, what has various magnitude | sizes can be used. That is, the inorganic porous body may be a bulk material, a powder, or a film. Further, when the inorganic porous material is a powder, it may be a coarse particle having an average particle diameter exceeding 10 μm, or may be a fine particle of 1 to 10 μm. Further, the inorganic porous material may be nanoparticles having an average particle size of less than 1 μm.

When the inorganic porous material is a powder, the shape is not particularly limited, and those having various shapes can be used according to the purpose. That is, the inorganic porous material may be irregular particles or spherical particles. In order to apply the oxide composite according to the present invention to photonic crystals, drug delivery, etc., the inorganic porous material is preferably a spherical particle.
Here, “spherical” means that when a plurality of (preferably 20 or more) particles manufactured under the same conditions are observed with a microscope or the like, the average value of sphericity of each particle is 13%. It means the following. The “sphericity” is an index representing the degree of deviation of the outer shape of each particle from the perfect circle, and the circumscribed circle and the particle with respect to the radius (r ₀ ) of the smallest circumscribed circle in contact with the particle surface. This is a value represented by the ratio (= Δr _max × 100 / r ₀ (%)) of the maximum value (Δr _max ) of the distance in the radial direction from each point on the surface. When applying the oxide composite according to the present invention to photonic crystals, drug delivery, and the like, the smaller the sphericity of the inorganic porous material powder, the better. The sphericity is more preferably 7% or less, and further preferably 3% or less.

In the case where the inorganic porous material is a powder, the powder may have a large variation in particle size, or may have a small variation in particle size (so-called “monodisperse”). May be.
Here, “monodisperse” means that the monodispersity represented by the following formula (1) is 10% or less. In applying the oxide complex according to the present invention to photonic crystals, drug delivery, and the like, the smaller the monodispersity, the better in order to obtain high characteristics. The monodispersity is more preferably 5% or less.
Monodispersity = (standard deviation of particle diameter / average particle diameter) × 100 (%) (1)

  The pore diameter and the porosity contained in the inorganic porous body are not particularly limited, and porous bodies having various pore diameters and / or porosity can be used depending on the purpose. In general, the smaller the pore size, the smaller the particle size of the metal oxide obtained by oxidizing the metallocene or its derivative. In general, as the porosity increases, an oxide composite having a higher metal oxide content can be obtained.

  Among inorganic porous materials that satisfy the above conditions, porous materials having mesopores (mesoporous materials) contain a relatively large amount of nanometer-sized uniform pores. It is suitable as an inorganic porous material for synthesizing an oxide composite in which substances are uniformly dispersed. A mesoporous material having a spherical shape (spherical mesoporous material) is suitable as an inorganic porous material for synthesizing an oxide composite having a high filling property. Furthermore, a spherical mesoporous material that is monodispersed (monodispersed spherical mesoporous material) is particularly suitable as an inorganic porous material for producing an oxide composite used for a photonic crystal or the like. In addition, the manufacturing method of a spherical mesoporous body (and a monodispersed spherical mesoporous body) is mentioned later.

  When an inorganic porous material is added to a first solution in which a predetermined amount of metallocene or a derivative thereof is dissolved in a thermally polymerizable solvent, the first solution is impregnated into the pores of the inorganic porous material. When the type of the first solvent is optimized, the first solution can be impregnated very easily into the pores. In addition, when impregnating a 1st solution, you may perform processes, such as provision of an ultrasonic vibration, heating, and deaeration, as needed.

  The polymerization step is a step of heating the inorganic porous body impregnated with the first solution in the pores to polymerize the thermally polymerizable first solvent. Thereby, a polymer (copolymer) in which the metallocene or a derivative thereof is fixed is formed. As the polymerization conditions, optimum conditions are selected according to the type of the first solvent. The optimum polymerization temperature and polymerization time vary depending on the type of the first solvent, but the polymerization temperature is usually 50 ° C. to 300 ° C., and the polymerization time is 5 minutes to 24 hours.

In the first heat treatment step, the inorganic porous material subjected to the polymerization treatment of the first solvent is heat-treated at 400 ° C. or higher in an atmosphere containing oxygen, and the metallocene or a derivative thereof is thermally decomposed to thereby decompose the first metal oxide ( This is a process of generating an amorphous state.
The first heat treatment is performed in an atmosphere containing oxygen (for example, in the air, pure oxygen, or the like) in order to thermally decompose the polymer containing metallocene or a derivative thereof to oxidize and remove organic substances.
The heat treatment temperature is preferably 400 ° C. or higher. When the heat treatment temperature is less than 400 ° C., the thermal decomposition does not proceed completely, and organic matter remains, which is not preferable.
Furthermore, the heat treatment time is selected in accordance with the heat treatment temperature so that an oxide composite having the desired composition and characteristics can be obtained.

The optimum heat treatment temperature is selected according to the type of metallocene or derivative thereof, the kind of first solvent, the use of the oxide composite, and the like.
For example, when a first metal oxide obtained by oxidizing metallocene or a derivative thereof is used as a catalyst, the surface of the first metal oxide is preferably exposed in order to obtain high catalytic activity. In such a case, it is preferable to perform heat treatment at a relatively low temperature so that the pores of the inorganic porous material are not blocked by the heat treatment.

On the other hand, when the magnetic properties of the first metal oxide are used, the surface of the first metal oxide is not necessarily exposed. In this case, an optimal temperature is selected according to the type of the first metal oxide so that the first metal oxide having the target crystal structure can be obtained and the highest magnetic characteristics can be obtained. Furthermore, in order to obtain a spherical oxide composite, the heat treatment temperature is preferably equal to or lower than the temperature at which the shape of the inorganic porous body can be maintained.
For example, when a silica porous body having mesopores is used as the inorganic porous body and iron oxide is generated in the pores, when the heat treatment temperature is 700 to 900 ° C., γ-Fe ₂ O ₃ nanoparticles are formed in the pores. Can be generated. When the heat treatment temperature is higher than 900 ° C., the mesopore structure is broken and the pores are blocked, but a composite of silica and iron oxide nanoparticles is obtained. When the heat treatment temperature is 1000 ° C., γ-Fe ₂ O ₃ A composite in which nanoparticles are dispersed in a silica matrix is obtained. When the heat treatment temperature is 1100 ° C. to 1200 ° C., a composite in which ε-Fe ₂ O ₃ nanoparticles are dispersed in a silica matrix is obtained. In the heat treatment temperature range of 1000 to 1100 ° C., γ-Fe ₂ O ₃ and ε-Fe ₂ O ₃ coexist with silica. When the heat treatment temperature exceeds 1200 ° C., silica is partially melted, which is not preferable.

  In the method according to the present invention, a relatively large amount of the first metal oxide can be introduced into the pores by one treatment, but the above-described impregnation step, polymerization step and heat treatment step are repeated a plurality of times. May be. By repeating these steps a plurality of times, an oxide composite having a higher first metal oxide content can be produced.

When the method according to this embodiment is used, an oxide composite in which a first metal oxide obtained by thermally decomposing a metallocene or a derivative thereof is dispersed inside an inorganic porous body can be obtained.
In this case, when the impregnation condition of the first solution containing the metallocene or the derivative thereof is optimized, an oxide composite in which the content of the first metal oxide is 5 wt% or more, 10 wt% or more, or 15 wt% or more is obtained. can get. Further, when the impregnation-polymerization-heat treatment is repeated a plurality of times, an oxide composite having the first metal oxide content of 20% or more or 30% or more is obtained.
Further, when a spherical inorganic porous material is used, when the heat treatment conditions are optimized, a spherical oxide composite having a sphericity of 13% or less, 7% or less, or 3% or less is obtained.
In the case of using a monodispersed spherical inorganic porous material, when the heat treatment conditions are optimized, a monodispersed spherical oxide composite having a monodispersity of 10% or less or 5% or less is obtained.
Furthermore, when a monodispersed spherical mesoporous material containing silica and ferrocene or a derivative thereof are used as starting materials, the average particle size is 50 nm to 2 μm (or 100 nm to 1 μm) when the synthesis conditions are optimized. And a monodispersed spherical silica-iron oxide composite containing 5 wt% or more of γ-Fe ₂ O ₃ nanoparticles or ε-Fe ₂ O ₃ nanoparticles.

  Next, an oxide composite and a method for manufacturing the same according to the second embodiment of the present invention will be described. The method for manufacturing an oxide composite according to the present embodiment includes a first impregnation step, a polymerization step, a first heat treatment step, a second impregnation step, and a second heat treatment step. The oxide composite according to the present embodiment is obtained by the method according to the present embodiment. Among these, the first impregnation step and the polymerization step are the same as those in the first embodiment, and thus description thereof is omitted.

In the first heat treatment step, the inorganic porous material that has been subjected to the polymerization treatment of the first solvent is heat-treated at 400 ° C. or higher in an atmosphere containing oxygen, and the metallocene or a derivative thereof is thermally decomposed to form the first metal oxide. It is a process of generating.
In this Embodiment, the heat processing temperature in a 1st heat processing process should just be the temperature which the pore contained in an inorganic porous body does not obstruct | occlude. In general, the first metal oxide formed in the pores is more likely to be in an amorphous state as the heat treatment temperature is lower, and is more likely to be crystallized as the heat treatment temperature is higher. The heat treatment temperature may be either the temperature at which the first metal oxide is in an amorphous state or the temperature at which it is in a crystalline state. In particular, when the heat treatment is performed at a temperature at which the first metal oxide is in an amorphous state, there is an advantage that the reaction can easily proceed in the second heat treatment step described later.
The optimum temperature at which the pores of the inorganic porous body are not blocked and the first metal oxide can be kept in an amorphous state is the composition of the inorganic porous body and the first metal oxide, and the introduction of the first metal oxide. It depends on the amount. For example, in the case where the inorganic porous body is composed mainly of silica and the first metal oxide is composed mainly of iron oxide, a heat treatment is performed in order to generate amorphous iron oxide. The temperature is preferably 400 to 600 ° C.
Other points regarding the first heat treatment step are the same as those in the first embodiment, and thus the description thereof is omitted.

The second impregnation step is a step of impregnating the second solution obtained by dissolving the metal compound in the second solvent into the pores of the oxide composite obtained in the first heat treatment step.
A “metal compound” refers to a compound that contains a metal element and can be dissolved in a second solvent. Some solvent-soluble metal compounds have a pH of the solution shifted to the acidic side or the alkaline side. When the pH shift becomes large, the inorganic porous body or oxide composite may be dissolved. Therefore, the metal compound is preferably a compound in which the second solution obtained by dissolving in the second solvent does not dissolve the inorganic porous body and the oxide composite.
For example, when the first metal oxide is an oxide containing Fe, the first metal oxide may be dissolved if the pH of the second solution is greatly shifted to the acidic side. In this case, the metal compound is preferably one in which the pH of the second solution is 3 or more, more preferably 4 or more.
Further, for example, when the inorganic porous body contains silica as a main component, the inorganic porous body may be dissolved if the pH of the second solution is largely shifted to the alkaline side. In this case, the metal compound preferably has a pH of the second solution of 9 or less, more preferably 8 or less.

The kind of metal element contained in the metal compound is not particularly limited, and depends on the composition of the first metal oxide obtained in the first heat treatment step and the composition of the second metal oxide obtained in the second heat treatment step. Select the most suitable one. Specific examples of the metal element include Mn, Zn, Co, Ni, Pb, Bi, Sr, Ba, and a rare earth element.
In addition, as a metal compound containing these metal elements,
(1) Chlorides, nitrates, sulfates, carbonates and other salts,
(2) metallocene,
(3) alkoxide,
(4) Metal complexes such as acetylacetonate and bipyridine complexes,
and so on.

As the second solvent, an optimum solvent is selected according to the type of the metal compound. Specifically, as the second solvent,
(1) Organic solvents such as water and alcohol, or a mixture thereof,
(2) Thermally polymerizable solvents such as furfuryl alcohol, aniline, styrene,
and so on.
The concentration of the metal compound in the second solution is not particularly limited, and an optimum concentration should be selected according to the solubility of the metal compound in the second solvent, the amount of the metal compound introduced into the oxide composite, and the like. That's fine. In general, the higher the concentration of the metal compound, the more metal compound can be introduced into the pores by one impregnation treatment.
When the oxide complex is added to the second solution, the second solution is impregnated into the pores of the oxide complex. When impregnating the second solution, treatments such as application of ultrasonic vibration, heating, and deaeration may be performed as necessary. After impregnation, the metal compound can be fixed in the pores by drying or polymerizing a heat-polymerizable solvent.

The second heat treatment step is a step of heating the oxide composite in which the metal compound is introduced into the pores at 400 ° C. or higher in an atmosphere containing oxygen. Thereby, the second metal oxide can be generated in the oxide composite.
The second heat treatment is performed in an atmosphere containing oxygen (e.g., in the air, pure oxygen, or the like) in order to thermally decompose the metal compound into oxides (including those in an amorphous state).
The heat treatment temperature in the second heat treatment step is preferably 400 ° C. or higher. When the heat treatment temperature is less than 400 ° C., thermal decomposition becomes insufficient.
Furthermore, as the heat treatment time, an optimum time is selected according to the heat treatment temperature so that an oxide composite having a desired composition and characteristics can be obtained. In general, the longer the heat treatment time, the more the crystallization or complex oxide formation of the second metal oxide proceeds in a relatively short time.

The optimum heat treatment temperature is selected according to the composition of the first metal oxide and the second metal oxide, the type of the metal compound, the use of the oxide composite, and the like.
In general, the lower the heat treatment temperature, the second metal oxide tends to be in an amorphous state or a mixture of metal oxides formed by oxidation of the first metal oxide and the metal compound. On the other hand, the higher the heat treatment temperature, the second metal oxide tends to be in a crystalline state, or the first metal oxide and the metal oxide generated by oxidation of the metal compound react to form a composite oxide. . In particular, when the second metal oxide functions as a magnetic material, it is preferable to perform heat treatment at a relatively high temperature to crystallize the second metal oxide or to form a composite oxide. Furthermore, in order to obtain a spherical oxide composite, the heat treatment temperature is preferably equal to or lower than the temperature at which the shape of the inorganic porous body can be maintained.
For example, when a silica porous body having mesopores is used as the inorganic porous body and amorphous iron oxide is generated as the first metal oxide in the pores, a Co compound is further introduced into the pores, and CoFe _{When 2} O ₄ is produced, the heat treatment temperature is preferably 800 to 1000 ° C.
Note that the second impregnation step and the second heat treatment step described above may be repeated a plurality of times as necessary.

When the method according to the present embodiment is used, second metal oxides having various compositions can be formed inside the inorganic porous body. Specifically, as the crystalline second metal oxide,
(1) General formula: Spinel type ferrite represented by MFe ₂ O ₄ (where M is any one or more divalent metal elements selected from Mn, Ni, Co, Zn, etc.),
(2) General formula: Garnet type ferrite represented by M ₃ Fe ₅ O ₁₂ (where M is any one or more trivalent metal elements selected from rare earth metals),
(3) General formula: magnetoplumbite type ferrite represented by MFe ₁₂ O ₁₉ (where M is any one or more divalent metal element selected from Ba, Sr and Pb),
(4) General formula: perovskite type ferrite represented by MFeO ₃ (where M is any one or more trivalent metal elements selected from rare earth metals),
and so on.
In addition, in the oxide composite, a metal oxide obtained by oxidizing the first metal oxide and the metal compound in addition to the above-described spinel ferrite etc. according to the second impregnation condition, the second heat treatment condition, and the like. May be included.

Further, when the first impregnation condition and the second impregnation condition are optimized, an oxide composite in which the content of the second metal oxide is 5 wt% or more, 10 wt% or more, or 15 wt% or more is obtained. Further, when the impregnation-polymerization-heat treatment is repeated a plurality of times, an oxide composite having a second metal oxide content of 20% or more or 30% or more is obtained.
Further, when a spherical inorganic porous body is used, a spherical oxide composite having a sphericity of 13% or less, 7% or less, or 3% or less when the first and second heat treatment conditions are optimized. Is obtained. Similarly, in the case of using a monodispersed spherical inorganic porous material, when the first and second heat treatment conditions are optimized, the monodispersed spherical oxide composite having a monodispersity of 10% or less or 5% or less The body is obtained.
Furthermore, when a monodispersed spherical mesoporous material containing silica and ferrocene or a derivative thereof are used as starting materials, the average particle size is 50 nm to 2 μm (or 100 nm to 1 μm) when the synthesis conditions are optimized. In addition, a monodispersed spherical silica-oxide composite containing 5 wt% or more of the second oxide nanoparticles is obtained.

  Next, an oxide composite and a method for manufacturing the same according to the third embodiment of the present invention will be described. The method for manufacturing an oxide composite according to the present embodiment includes a first impregnation step, a polymerization step, a first heat treatment step, and a third heat treatment step. The oxide composite according to the present embodiment is obtained by the method according to the present embodiment. Among these, the first impregnation step and the polymerization step are the same as those in the first embodiment, and thus description thereof is omitted.

In the first heat treatment step, the inorganic porous material that has been subjected to the polymerization treatment of the first solvent is heat-treated at 400 ° C. or higher in an atmosphere containing oxygen, and the metallocene or a derivative thereof is thermally decomposed to form the first metal oxide. It is a process of generating.
In this Embodiment, the heat processing temperature in a 1st heat processing process should just be a temperature which can reduce | restore a 1st metal oxide in the 3rd heat processing process mentioned later. That is, the heat treatment temperature may be a temperature at which pores contained in the inorganic porous body are closed, or a temperature at which the first metal oxide is crystallized. However, in order to facilitate the reduction of the first metal oxide, the heat treatment temperature in the first heat treatment step is preferably a temperature that does not block the pores and does not crystallize the first metal oxide. Generally, the lower the heat treatment temperature is, the more the pores contained in the inorganic porous material are not blocked, and the first metal oxide can be stopped in an amorphous state.
The optimum temperature at which the pores of the inorganic porous body are not blocked and the first metal oxide can be kept in an amorphous state is the composition of the inorganic porous body and the first metal oxide, and the introduction of the first metal oxide. It depends on the amount. For example, in the case where the inorganic porous body is composed mainly of silica and the first metal oxide is composed mainly of iron oxide, a heat treatment is performed in order to generate amorphous iron oxide. The temperature is preferably 400 to 600 ° C.
Other points regarding the first heat treatment step are the same as those in the first embodiment, and thus the description thereof is omitted.

The third heat treatment step is a step of heat-treating the oxide composite obtained in the first heat treatment step at 400 ° C. or higher in an inert atmosphere or a reducing atmosphere. Thereby, the third metal oxide can be generated in the oxide composite.
The third heat treatment is performed in an inert atmosphere or a reducing atmosphere in order to reduce the first metal oxide. Since the reduction proceeds relatively easily when the first metal oxide is in an amorphous state, the third heat treatment can be performed in an inert atmosphere such as an N ₂ atmosphere or an Ar atmosphere. On the other hand, when the crystallization of the first metal oxide is proceeding, the reduction is difficult to proceed. Therefore, the third heat treatment is preferably performed in a reducing atmosphere such as a hydrogen atmosphere.
The heat treatment temperature in the third heat treatment step is preferably 400 ° C. or higher. If the heat treatment temperature is less than 400 ° C., the reduction is insufficient.
As the heat treatment time, an optimum time is selected according to the heat treatment temperature so that an oxide composite having a desired composition and characteristics can be obtained. In general, the higher the heat treatment temperature is, the more the reduction can proceed in a relatively short time.

The optimum heat treatment temperature varies depending on the composition and crystal state of the first metal oxide, the atmosphere during firing, and the like.
The heat treatment temperature may be a temperature at which the valence of the metal element contained in at least the first metal oxide changes. Generally, the higher the heat treatment temperature and / or the stronger the reducing property of the atmosphere during the heat treatment, the more the valence of the metal element can be changed in a relatively short time. Moreover, in order to obtain a spherical oxide composite, the heat treatment temperature is preferably equal to or lower than the temperature at which the shape of the inorganic porous body can be maintained.
For example, when the first metal oxide is amorphous iron oxide and the heat treatment is performed in an N ₂ atmosphere, the heat treatment temperature is preferably 900 ° C. or higher.
Note that the method according to the present embodiment may be used alone, or may be used in combination with the second embodiment. That is, the oxide composite that has been impregnated into the pores of the metal compound (second impregnation step) and fired in an atmosphere containing oxygen (second heat treatment step) is fired in a reducing atmosphere ( A third heat treatment step may be performed.

When the method according to the present embodiment is used, third metal oxides having various compositions can be formed inside the inorganic porous body. For example, when the first metal oxide is iron oxide, firing it in a reducing atmosphere generates Fe ₃ O ₄ having higher saturation magnetization than γ-Fe ₂ O ₃ or ε-Fe ₂ O _3. Can do.
In the oxide composite, a metal oxide obtained by oxidizing the first metal oxide, the second metal oxide, and the metal compound in addition to the third metal oxide according to the conditions of the previous process. May be included.

Further, when the first impregnation condition (and the second impregnation condition) is optimized, an oxide composite in which the content of the third metal oxide is 5 wt% or more, 10 wt% or more, or 15 wt% or more is obtained. . Further, when the impregnation-polymerization-heat treatment is repeated a plurality of times, an oxide composite having a third metal oxide content of 20% or more or 30% or more is obtained.
Further, when the spherical inorganic porous material is used, the sphericity is 13% or less, 7% or less, or 3% or less when the first and third heat treatment conditions (and the second heat treatment conditions) are optimized. A spherical oxide composite is obtained.
Similarly, in the case of using a monodispersed spherical inorganic porous material, when the first and third heat treatment conditions (and the second heat treatment conditions) are optimized, the monodispersity is 10% or less, or 5% or less. A monodisperse spherical oxide complex is obtained.
Furthermore, when a monodispersed spherical mesoporous material containing silica and ferrocene or a derivative thereof are used as starting materials, the average particle size is 50 nm to 2 μm (or 100 nm to 1 μm) when the synthesis conditions are optimized. In addition, a monodispersed spherical silica-oxide composite containing 5 wt% or more of the third metal oxide nanoparticles is obtained.

Next, a method for producing a spherical mesoporous material used as an inorganic porous material for synthesizing the oxide composite according to the present invention will be described.
In the case where the heat treatment of the inorganic porous body is performed, if the heat treatment conditions are optimized, an oxide composite in which the outer shape of the inorganic porous body is maintained as it is can be obtained. That is, when a spherical mesoporous material (or monodispersed spherical mesoporous material) is used as the inorganic porous material, a spherical (or spherical monodispersed) oxide composite can be obtained by optimizing the heat treatment conditions.
In addition, in the case of using a spherical mesoporous material whose pores extend radially from the center toward the surface as the inorganic porous material, when the heat treatment conditions are optimized, the metal oxide nanoparticles are formed in the radially extending pores. A supported oxide composite is obtained.

Among such spherical mesoporous materials, those containing silica can be obtained by three-dimensionally polymerizing a raw material containing a silica raw material using a surfactant as a template. In particular,
(1) Add appropriate amount of surfactant and silica raw material (and other raw materials if necessary) to water, and hydrolyze silica raw material (and other raw materials added as needed) under basic conditions Let
(2) separating the product from the solution and removing the surfactant;
(See, for example, JP-A-10-328558 and JP-A-2004-2161).

  At this time, when the concentration of the surfactant in the solution, the concentration of the silica raw material, and the ratio of the two are optimized, a spherical mesoporous body in which mesopores are radially arranged from the center toward the outside is obtained. Furthermore, when a specific kind of alcohol and / or hydrophilic polymer is added to the solution, a monodispersed spherical mesoporous material having a fine particle diameter of 2 μm or less is obtained.

Silica raw materials include
(1) Tetraalkoxysilanes (silane compounds) such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane,
(2) Trimethoxysilanol, triethoxysilanol, trimethoxymethylsilane, trimethoxyvinylsilane, triethoxyvinylsilane, triethoxy-3-glycidoxypropylsilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ- (methacryloxypropyl) trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, etc. Trialkoxysilane (silane compound),
(3) dialkoxysilanes (silane compounds) such as dimethoxydimethylsilane, diethoxydimethylsilane, diethoxy-3-glycidoxypropylmethylsilane, dimethoxydiphenylsilane, dimethoxymethylphenylsilane,
(4) Sodium metasilicate (Na ₂ SiO ₃ ), sodium orthosilicate (Na ₄ SiO ₄ ), sodium disilicate (Na ₂ Si ₂ O ₅ ), sodium tetrasilicate (Na ₂ Si ₄ O ₉ ), water Sodium silicate such as glass (Na ₂ O · nSiO ₂ , n = 2 to 4),
(5) Kanemite (NaHSi ₂ O ₅ .3H ₂ O), sodium disilicate crystals (α, β, γ, δ-Na ₂ Si ₂ O ₅ ), macatite (Na ₂ Si ₄ O ₉ ), eyelite ( _{Na 2 Si 8 O 17 · xH} 2 O), magadiite _{(Na 2 Si 14 O 17 ·} xH 2 O), kenyaite _{(Na 2 Si 20 O 41 ·} xH 2 O) layered silicates, such as,
(6) Precipitating silica such as Ultrasil (Ultrasil), Cab-O-Sil (Cabot), HiSil (Pittsburgh Plate Glass), colloidal silica, fumed silica such as Aerosil (Degussa-Huls),
Etc. can be used.

Among these, tetraalkoxysilane is suitable as a silica raw material because it has a large number of silanol bonds generated by hydrolysis and can form a strong skeleton.
In addition, these silica raw materials may be used alone or in combination of two or more. However, when two or more kinds of silica raw materials are used, the reaction conditions during the production of the spherical mesoporous material may be complicated. In such a case, the silica raw material is preferably used alone.

Further, the spherical mesoporous material may be made of only silica, or may comprise oxides of the metal element M ₁ other than silica. The metal element M ₁ is not particularly limited, those capable of producing a divalent or more metal alkoxides are preferred. If the metal element M ₁ can produce a metal alkoxide having a valence of 2 or more, a spherical mesoporous material containing an oxide of the metal element M ₁ can be easily produced. Examples of the metal element _{M 1,} specifically, is Al, Ti, Mg, Zr and the like.
The content of silica contained in the spherical mesoporous material is not particularly limited, and an optimal content is selected according to the use of the oxide composite.

The raw material containing a metal element M ₁ is,
(1) Al-containing alkoxides such as aluminum butoxide (Al (OC ₄ H ₉ ) ₃ ), aluminum ethoxide (Al (OC ₂ H ₅ ) ₃ ), aluminum isopropoxide (Al (OC ₃ H ₇ ) ₃ ) And salts such as sodium aluminate and aluminum chloride,
(2) Ti such as titanium isopropoxide (Ti (Oi-C ₃ H ₇ ) ₄ ), titanium butoxide (Ti (OC ₄ H ₉ ) ₄ ), titanium ethoxide (Ti (OC ₂ H ₅ ) ₄ ), etc. Containing alkoxide,
(3) Alkoxide containing Mg such as magnesium methoxide (Mg (OCH ₃ ) ₂ ), magnesium ethoxide (Mg (OC ₂ H ₅ ) ₂ ),
(4) Zr such as zirconium isopropoxide (Zr (Oi-C ₃ H ₇ ) ₄ ), zirconium butoxide (Zr (OC ₄ H ₉ ) ₄ ), zirconium ethoxide (Zr (OC ₂ H ₅ ) ₄ ) Containing alkoxide,
Etc. can be used.

The surfactant is preferably one represented by the following formula (2).
_{CH 3 - (CH 2) n} -N + (R 1) (R 2) (R 3) X - ··· (2)
_{(Wherein, R 1, R 2, R} 3 is a 1 to 3 carbon atoms, the same or different alkyl group, X is a halogen atom, n represents 8-21 integer.)
Among the surfactants represented by the formula (2), alkyltrimethylammonium halides (for example, hexadecyltrimethylammonium halide, octadecyltrimethylammonium halide, nonyltrimethylammonium halide, decyltrimethylammonium halide, undecyltrimethylammonium halide, dodecyltrimethyl) Ammonium halide etc.) are preferable, and alkyltrimethylammonium bromide or alkyltrimethylammonium chloride is particularly preferable.

In order to obtain a spherical mesoporous material having mesopores radially arranged from the center to the outside, the concentration of the silica raw material (and other raw materials added as necessary) in the solution is 0.005 mol / L or more and 0.05 mol / L or less are preferable, more preferably 0.007 mol / L or more and 0.045 mol / L or less, and still more preferably 0.009 mol / L or more and 0.04 mol / L or less.
Similarly, the concentration of the surfactant in the solution is preferably 0.005 mol / L or more and 0.04 mol / L or less, more preferably 0.007 mol / L or more and 0.03 mol / L or less, more preferably 0. It is 0.008 mol / L or more and 0.018 mol / L or less.
Furthermore, the ratio (molar ratio) of the surfactant / silica raw material (and other raw materials added as necessary) is preferably 0.1 or more and 3 or less, more preferably 0.2 or more and 2.7 or less. More preferably, it is 0.3 or more and 2.5 or less.

  When alcohol is added to the solution, the alcohol may be any of monovalent alcohols such as methanol, ethanol, and propanol, divalent alcohols such as ethylene glycol, and trivalent alcohols such as glycerin. In this case, in order to obtain a spherical mesoporous material having a fine particle size of 2 μm or less and a narrow particle size distribution, the amount of alcohol added is preferably 5 to 80, more preferably 100% of the water volume. Is 7 to 70, more preferably 10 to 60.

  In the case where a hydrophilic polymer is added to the solution in addition to or in place of the alcohol, the hydrophilic polymer is preferably polyvinyl alcohol or polyethylene glycol. In this case, the molecular weight of the hydrophilic polymer is preferably 200 to 50000, more preferably 300 to 30000. In order to obtain a spherical mesoporous material having a fine particle size of 2 μm or less and monodispersed, the concentration of the hydrophilic polymer in the solution is preferably 0.1 to 20% by weight, more preferably. Is 0.5 to 10% by weight.

A basic substance is added to the solution containing these raw materials in order to make the solution basic and hydrolyze the silica raw materials. Specific examples of the basic substance include sodium hydroxide and aqueous ammonia. The addition amount of the basic substance is selected in accordance with the type and concentration of the raw material, the characteristics of the spherical mesoporous material to be produced, and the like. Generally, when the addition amount of the basic substance is too small, the yield is extremely lowered. On the other hand, when the addition amount of the basic substance is too large, it may be difficult to form a porous body. The addition amount of the basic substance is specifically the alkali equivalent of a basic substance by a value obtained by dividing the number of moles of silicon and the metal element M ₁ in the raw material, if the basic substance is a strong base, 0 0.1 to 0.9 is preferable, 0.2 to 0.5 is more preferable, and 0.2 to 5 is preferable when the basic substance is a weak base, and 1 to 3 is more preferable.

When a silane compound such as tetraalkoxysilane is used as the silica material, this is used as a starting material as it is.
On the other hand, when a compound other than a silane compound is used as the silica raw material, a basic material such as sodium hydroxide is added in advance to the silica raw material in water (or an alcohol aqueous solution to which an alcohol is added if necessary). Add. The addition amount of the basic substance is preferably about equimolar to the silicon atom in the silica raw material. When a basic substance is added to a solution containing a silica raw material other than the silane compound, a part of the Si— (O—Si) ₄ bond already formed in the silica raw material is cleaved to obtain a uniform solution. The amount of the basic substance contained in the solution affects the yield and porosity of the spherical mesoporous material. Therefore, after a uniform solution is obtained, a dilute acid solution is added to the solution, and the excess present in the solution is added. Neutralize basic substances. The addition amount of the dilute acid solution is preferably an amount corresponding to 1/2 to 3/4 times mol of silicon atoms in the silica raw material.

Silica materials preliminary process is performed as necessary to a predetermined amount of water and surfactant, and, optionally, a raw material, an alcohol and / or a hydrophilic polymer added containing a metal element M _1, which Further, a basic substance is added to hydrolyze under basic conditions. Thereby, the surfactant functions as a template, and a silicon-containing oxide (hereinafter referred to as “precursor”) containing the surfactant therein is obtained.

Next, by separating the precursor obtained from the solution and removing the surfactant from the precursor, a spherical mesoporous material containing silica is obtained. Further, by optimizing the manufacturing conditions, the average particle size of 50Nm～2.0Myuemu, pore size has a peak in 1.2Nm～3.0Nm, specific surface area of at 900m ² / g~1300m ² / g There is obtained a spherical mesoporous material which is monodispersed and / or has pores formed radially.
As a method for removing the surfactant, specifically,
(1) A firing method in which the precursor is fired at a predetermined temperature (300 to 1000 ° C., preferably 400 to 700 ° C.) for a predetermined time (30 minutes or more, preferably 1 hour or more) in the air or in an inert atmosphere. ,
(2) The precursor is immersed in a good solvent for a surfactant (for example, methanol containing a small amount of hydrochloric acid), and stirred while heating at a predetermined temperature (for example, 50 to 70 ° C.), and the interface in the precursor An ion exchange method to extract the active agent,
and so on.

Next, the effect | action of the oxide composite based on this invention and its manufacturing method is demonstrated.
In the case of producing an oxide composite by impregnating a metal oxide precursor in the pores of a porous body and oxidizing the precursor, when using a metal salt such as iron nitrate as the precursor, the metal salt Must be dissolved in a suitable solvent. However, since the solubility of the metal salt in the solvent is relatively small, there is a limit to the amount of metal oxide that can be introduced into the pores by a single treatment.
In contrast, metallocene or a derivative thereof is dissolved in a very large amount in a certain solvent. For example, the solubility of ferrocene derivatives such as ferrocene carbaldehyde in furfuryl alcohol is 2 g / mL or more. Therefore, a larger amount of metal oxide than in the prior art can be introduced into the pores by one treatment. Further, a larger amount of metal oxide can be introduced into the pores by repeating impregnation, polymerization, and heat treatment a plurality of times.

In addition, when the pores are impregnated with a metal salt solution and heat-treated, the solvent first evaporates by heating, and the metal salt tends to go out of the pores due to its vapor pressure. For example, in the case of generating iron oxide using an iron salt such as nitrate, when the iron salt goes out of the pores during the heat treatment, not only the amount of iron oxide formed in the pores is reduced, Antiferromagnetic α-Fe ₂ O ₃ which is a stable phase and does not exhibit magnetism is easily generated.
On the other hand, when a thermopolymerizable solvent is used as a solvent for dissolving metallocene or a derivative thereof, the metallocene or a derivative thereof can be fixed to the polymer matrix by a polymerization treatment. Therefore, metallocene or a derivative thereof is hardly scattered outside the pores during the heat treatment, and a large amount of metal oxide can be generated in the pores.
In addition, when mesoporous silica and ferrocene or derivatives thereof are used as starting materials, γ-Fe ₂ O ₃ and ε-Fe ₂ O ₃ exhibiting ferromagnetism are generated in the pores when the manufacturing conditions are optimized. Can be made. The reason why α-Fe ₂ O ₃ is less likely to be generated by the method according to the present invention is unclear, but is related to the inhibition of grain growth in nanopores and the interaction between iron oxide and silica. It is thought that.

In addition, when the heat treatment conditions are optimized, an oxide composite that retains the shape of the inorganic porous body almost as it is can be obtained. Therefore, for example, when nanometer-order monodispersed spherical particles are used as the inorganic porous body, an oxide composite composed of nanometer-order monodispersed spherical particles can be obtained. Therefore, in addition to application to magnetic fluid, magnetic separation, MRI image diagnosis, etc., application to a photonic crystal having a novel function is possible.
Furthermore, since silica can be modified with a silane coupling agent, an enzyme or the like can be immobilized by immobilizing a special functional group or ligand. Therefore, if mesoporous silica is used as a host and a magnetic material such as iron oxide is combined, it can be applied to drug delivery utilizing magnetic force.

Further, when a metal compound is further introduced into the pores of the oxide composite obtained in the first heat treatment step and heat treatment is performed under a predetermined condition, a plurality of metal elements such as spinel ferrite and garnet ferrite are contained. A composite of magnetic particles and an inorganic porous material can be obtained. In particular, when an amorphous first metal oxide is generated in the pores of an inorganic porous body, and another metal source is added and reacted therewith, a magnetic compound such as spinel ferrite can be easily synthesized. Can do. This is because amorphous nanoparticles have a high surface area and a short diffusion distance to the inside of the particles, so that the reactivity with other compounds becomes extremely high.
Further, the spinel ferrite can be generated by a method in which a plurality of metallocenes or derivatives thereof are introduced into the pores and heat-treated in an oxidizing atmosphere. However, metallocene compounds other than ferrocene are generally expensive. On the other hand, when an inexpensive ferrocene and a metal compound are used as starting materials, oxide composites containing magnetic compounds having various compositions can be produced at low cost.

Furthermore, the characteristics of the magnetic material containing Fe can be changed by controlling the valence of Fe. However, when a compound containing Fe is fired in an oxidizing atmosphere, generally Fe ₂ O ₃ composed only of Fe ³⁺ is generated. In contrast, when a compound containing Fe is fired in an atmosphere having a low oxygen concentration (for example, a nitrogen atmosphere), a part of Fe becomes Fe ²⁺ . Therefore, for example, when Fe is contained in the oxide composite obtained in the first heat treatment step, when this is further fired in an inert atmosphere or a reducing atmosphere, γ-Fe ₂ O ₃ or ε-Fe ₂ O the Fe ₃ O ₄ high saturation magnetization than ₃ can be produced. In particular, when the first heat treatment condition is optimized so that the iron oxide is in an amorphous state, Fe ₃ O ₄ can be easily generated in the third heat treatment step.
Similarly, when the oxide composite obtained in the second heat treatment step is further baked in an inert atmosphere or a reducing atmosphere, a third metal in which all or part of the metal element contained in the second metal oxide is reduced. Oxides can be generated.

Example 1
[1. Preparation of monodispersed spherical mesoporous silica]
To 5 L of water and 5 L of methanol, 35.2 g (0.014 mol / L) of hexadecyltrimethylammonium chloride and 22.8 mL of 1N sodium hydroxide were added. To this solution, 13.2 g (0.011 mol / L) of tetramethoxysilane was added and completely dissolved. After dissolution, a white powder precipitated in about 200 seconds. The solution was further stirred at room temperature for 8 hours, and then the solution was left overnight. After standing, filtration and washing of the solution were repeated three times to obtain a white powder. The white powder was dried with a hot air dryer for 3 days, and then baked at 550 ° C. to remove organic components to obtain monodispersed spherical mesoporous silica. The pore diameter of silica determined by the BJH (Barret-Joyner-Halenda) method from the nitrogen adsorption characteristics was 21.0 mm (2.10 nm).

[2. Preparation of monodispersed spherical silica-iron oxide composite]
Ferrocene carbaldehyde 2.14 g (0.01 mol) was dissolved in 1 mL of furfuryl alcohol. 0.7 mL of this solution was added [1. The monodispersed spherical mesoporous silica powder obtained in the above was impregnated with 1.0 g. This was heated at 150 ° C. for 24 hours to polymerize the polymer in the pores. Further, this was heated in the atmosphere at 1000 ° C. for 3 hours to obtain a monodispersed spherical silica-iron oxide composite.

[3. Evaluation]
FIG. 1 shows a scanning electron micrograph of the obtained composite. The average particle size of the particles was 0.52 μm, and the monodispersity was 4.2%.
FIG. 2 shows the XRD pattern of this complex. The diffraction pattern other than the peak near 20 ° corresponding to the amorphous silica coincided with that of γ-Fe ₂ O ₃ . Moreover, Si / Fe ratio (atomic ratio) calculated | required from EDX was 86/14. This corresponds to 19 wt% in terms of Fe ₂ O ₃ .
FIG. 3 shows the magnetization curve of this powder measured at room temperature. FIG. 3 shows that the obtained composite exhibits superparamagnetism. The saturation magnetization of the composite was 5.77 emu / g. This is a value of 10 times or more the saturation magnetization of the monodispersed spherical silica containing magnetic iron oxide shown in Non-Patent Document 4. As a result of observation with a transmission electron microscope, it was confirmed that about 5 nm of iron oxide particles were dispersed inside the spherical silica.

(Example 2)
A monodispersed spherical silica-iron oxide composite was produced under the same conditions as in Example 1 except that the conditions for the heat treatment in the atmosphere were 1100 ° C. × 3 hours. The average particle diameter of the obtained particles was 0.51 μm, and the monodispersity was 3.8%.
FIG. 4 shows the XRD pattern of the obtained complex. The diffraction pattern other than the peak near 20 ° corresponding to the amorphous silica coincided with that of ε-Fe ₂ O ₃ .
FIG. 5 shows the magnetization curve of this powder measured at room temperature. FIG. 5 shows that the obtained composite exhibits ferromagnetism. The saturation magnetization of the composite was 3.65 emu / g. As a result of observation with a transmission electron microscope, it was confirmed that 10-20 nm iron oxide particles were dispersed inside the spherical silica.

(Example 3)
Ferrocene carbaldehyde 4.28 g (0.02 mol) was dissolved in 2 mL of furfuryl alcohol. 0.7 mL of this solution was immersed in the monodispersed spherical mesoporous silica synthesized in Example 1. This was heated at 150 ° C. for 24 hours to polymerize the polymer in the pores. Furthermore, this was baked at 500 degreeC for 6 hours in air | atmosphere, and the monodispersed spherical silica-iron oxide composite was obtained. The pore diameter of the composite obtained by the BJH method from the nitrogen adsorption characteristics was 19.0 mm (1.90 nm).

Example 4
1.02 g of the composite powder synthesized in Example 3 was impregnated with 0.42 mL of the ferrocenecarbaldehyde / furfuryl alcohol solution prepared in Example 2. This was heated at 150 ° C. for 24 hours to polymerize the polymer in the pores. Furthermore, this was baked at 500 degreeC for 6 hours in air | atmosphere. The pore diameter of the composite obtained by the BJH method from the nitrogen adsorption characteristics was 17.3 mm (1.73 nm).

(Example 5)
The composite powder synthesized in Example 4 was impregnated with 0.28 mL of the ferrocenecarbaldehyde / furfuryl alcohol solution. This was heated at 150 ° C. for 24 hours to polymerize the polymer in the pores. Furthermore, this was baked at 500 degreeC for 6 hours in air | atmosphere. The pore diameter of the composite obtained by the BJH method from the nitrogen adsorption characteristics was 16.7 mm (1.67 nm).

  About the composite_body | complex obtained in Examples 3-5, Si / Fe ratio (atomic ratio) was calculated | required by EDX. Table 1 shows the results. From Table 1, it can be seen that the amount of Fe introduced increases as the number of introductions of the ferrocenecarbaldehyde / furfuryl alcohol solution is increased.

(Example 6)
A monodispersed spherical silica-iron oxide composite was produced under the same conditions as in Example 1 except that the conditions for the heat treatment in the atmosphere were 900 ° C. × 3 hours. The average particle diameter of the obtained particles was 0.57 μm, and the monodispersity was 4.7%. As a result of analysis by XRD, the obtained particles were found to be a composite of γ-Fe ₂ O ₃ and amorphous silica. As a result of observation with a transmission electron microscope, it was confirmed that iron oxide particles of about 2 nm were dispersed in the mesopores of the spherical silica. The obtained particles had a BET specific surface area of about 350 m ² / g and a pore volume of 0.20 cm ³ / g. The saturation magnetization of the composite was 1.1 emu / g.

(Comparative Example 1)
1.35 g (0.005 mol) of iron (III) chloride hexahydrate was dissolved in 2 mL of methanol. The solution was impregnated with 0.7 g of the monodispersed spherical mesoporous silica powder synthesized in Example 1, and calcined in the atmosphere at 500 ° C. for 6 hours.
FIG. 6 shows a scanning electron micrograph of the obtained composite. From FIG. 6, it can be seen that a large number of irregular foreign substances are deposited around the spherical particles. The foreign material was identified as α-Fe ₂ O ₃ by XRD.

(Example 7)
[1. Preparation of monodispersed spherical mesoporous silica]
[1. ] Mono-dispersed spherical mesoporous silica was synthesized under the same conditions as in FIG.
[2. Preparation of monodispersed spherical silica-iron oxide composite]
Ferrocene carbaldehyde 2.14 g (0.01 mol) was dissolved in 1 mL of furfuryl alcohol. 0.7 mL of this solution was added [1. The monodispersed spherical mesoporous silica powder obtained in the above was impregnated with 1.0 g. This was heated at 150 ° C. for 24 hours to polymerize the polymer in the pores. Further, this was heated in the atmosphere at 500 ° C. for 6 hours to obtain a monodispersed spherical silica-iron oxide composite. In the high-angle XRD of this powder, no diffraction pattern corresponding to iron oxide was found, and the iron oxide was amorphous. This composite was further calcined at 1000 ° C. for 3 hours in a nitrogen stream.

[3. Evaluation]
FIG. 7 shows the Raman spectrum of the obtained powder. It was compared with the spectrum of a commercially available Fe ₃ O ₄ and γ-Fe ₂ O _3, closely resembles the spectrum of Fe ₃ O _4, it can be seen that the complex comprises Fe ₃ O _4.
FIG. 8 shows the magnetization curve of this powder measured at room temperature. FIG. 8 shows that the obtained composite exhibits superparamagnetism. The saturation magnetization of this composite was 11.4 emu / g. As a result of observation with a transmission electron microscope, it was confirmed that iron oxide particles of 3 to 5 nm were dispersed inside the spherical silica.

(Example 8)
In the same manner as in Example 7, a silica-amorphous iron oxide composite (fired in air at 500 ° C. for 6 hours) was obtained. This powder was dispersed in a methanol solution of cobalt nitrate (number of moles of Fe in the composite / number of moles of cobalt nitrate = 2), dried by a rotary evaporator, and cobalt nitrate was introduced into the pores of the composite. Thereafter, the powder was fired at 900 ° C. for 3 hours in the air. The XRD pattern of this powder was consistent with that of CoFe ₂ O ₄ . The obtained composite showed superparamagnetism at room temperature, and the saturation magnetization was 12.6 emu / g.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

  The oxide composite according to the present invention and the production method thereof are used as an oxide composite used for magnetic fluid, photonic crystal, drug delivery system, biomedical image, information recording, various oxidation catalysts, and the production method thereof. Can do.

2 is a scanning electron micrograph of the monodispersed spherical silica-iron oxide composite obtained in Example 1. FIG. 2 is an XRD pattern of a monodispersed spherical silica-iron oxide composite obtained in Example 1. FIG. 2 is a magnetization curve of the monodispersed spherical silica-iron oxide composite obtained in Example 1. 2 is an XRD pattern of a monodispersed spherical silica-iron oxide composite obtained in Example 2. FIG. 2 is a magnetization curve of a monodispersed spherical silica-iron oxide composite obtained in Example 2. 2 is a scanning electron micrograph of the silica-iron oxide composite obtained in Comparative Example 1. It is a Raman spectrum of the monodispersed spherical silica-iron oxide composite obtained in Example 7 and commercially available Fe ₃ O ₄ and γ-Fe ₂ O ₃ . 2 is a magnetization curve of the monodispersed spherical silica-iron oxide composite obtained in Example 7.

Claims (14)

A first impregnation step of impregnating the pores of the inorganic porous body with a first solution in which a metallocene or a derivative thereof is dissolved in a first solvent that is polymerized by heating;
A polymerization step of heating the inorganic porous body and polymerizing the first solvent;
The inorganic porous material, heat-treated at 400 ° C. or higher in an atmosphere containing oxygen, Bei example a first heat treatment step to produce the first metal oxide the metallocene or a derivative thereof by thermal decomposition,
The size of the pore is larger than the size of the metallocene or derivative thereof
Method for producing oxides complex.   The method for producing an oxide composite according to claim 1, wherein the first solvent is furfuryl alcohol.   The method for producing an oxide composite according to claim 1, wherein the inorganic porous body is a spherical particle. The method for producing an oxide composite according to any one of claims 1 to 3, wherein the inorganic porous body is a particle having a monodispersity represented by the formula (1) of 10% or less .
Monodispersity = (standard deviation of particle diameter / average particle diameter) × 100 (%) (1)   The method for producing an oxide composite according to any one of claims 1 to 4, wherein the inorganic porous body is a silica porous body.   6. The method according to claim 1, wherein in the first impregnation step, the metallocene or a derivative thereof is impregnated in the pores so that the content of the first metal oxide is 5 wt% or more. A method for producing the oxide composite according to 1. The method for producing an oxide composite according to any one of claims 1 to 6, wherein the metallocene or a derivative thereof contains Fe, Ni, or Co. The method for producing an oxide composite according to any one of claims 1 to 7, wherein the first metal oxide includes γ-Fe ₂ O ₃ or ε-Fe ₂ O ₃ . A second impregnation step of impregnating a second solution in which a metal compound is dissolved in a second solvent into the pores of the oxide composite obtained in the first heat treatment step;
The oxide complex further includes a second heat treatment step of heating the oxide complex at 400 ° C. or higher in an atmosphere containing oxygen to generate a second metal oxide in the oxide complex. The manufacturing method of the oxide composite in any one.   The method for producing an oxide composite according to claim 9, wherein the second metal oxide includes spinel ferrite, garnet ferrite, magnetoplumbite ferrite, or perovskite ferrite.   The oxide composite obtained in the first heat treatment step or the second heat treatment step is heat-treated at 400 ° C. or higher in an inert atmosphere or a reducing atmosphere to generate a third metal oxide in the oxide composite. The method for producing an oxide composite according to any one of claims 1 to 10, further comprising a third heat treatment step. The method for producing an oxide composite according to claim 11, wherein the third metal oxide includes Fe ₃ O ₄ .   The oxide composite obtained by the method in any one of Claim 1-12.   The oxide composite according to claim 13, which has a spherical shape.

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