JP7016119B2 - Porous metal oxide, manufacturing method of porous metal oxide - Google Patents

Description

The present invention relates to a metal oxide porous body and a method for producing a metal oxide porous body.

A material having a mesoporous structure is expected as a material having various physicochemical functions such as a catalyst having good selectivity due to the uniformity of its pores. In addition, since the nanostructured pores of the porous material exhibit a quantum effect, the mesoporous structure material is attracting attention in various fields from this viewpoint as well.

There are mesoporous oxides as materials for mesoporous structures, and mesoporous oxides have been developed mainly for silica. Due to its high surface area, mesoporous silica is effective in adsorbing various gases, liquids and toxic heavy metals. When using mesoporous materials such as mesoporous silica as an adsorbent, for example, for removing pollutants from water, adsorbing gases such as carbon dioxide, hydrogen, oxygen, methane, and sulfur dioxide, and separating biological substances and pharmaceuticals. It's being used. However, mesoporous silica does not have a function such as catalysis because the substance is silica.

On the other hand, many transition metal oxide powders have various catalytic properties. The transition metal oxide has a Lewis acid point, a Lewis base point, a Bronsted acid point, and a Bronsted base point, and is an active point that exerts various catalytic functions. However, much of its performance depends largely on the surface area of the powder. In general, the larger the surface area of an oxide, the more active sites these are, and the higher the catalytic function per unit mass, the higher the value.

Therefore, studies have also been conducted on non-silica mesoporous oxides.

For example, in Patent Document 1, at least a metal oxide to be doped in a solution of an organic solvent in which a template agent is present is added, and the added solution is stirred to uniformly disperse the metal oxide in the dispersion liquid. It is characterized by including a step of adding a transition metal compound forming a mesoporous structure oxide or a transition metal compound forming a mesoporous structure oxide and an acid by a sol-gel method to make the doped metal oxide solubilized under acidic conditions. A method for synthesizing a metal-doped mesoporous transition metal oxide in which a metal derived from the metal oxide is present with atomic level uniformity by the sol-gel method has been proposed. Patent Document 1 discloses an example in which Fe-doped mesoporous niobium oxide is prepared.

Patent Document 2 proposes a mesoporous metal oxide composite optical waveguide sensor characterized in that the surface of an optical amplification layer installed on the surface layer of the optical waveguide is coated with a mesoporous metal oxide thin film. Patent Document 2 discloses an example in which a mesoporous metal oxide WO ₃ is prepared.

Japanese Unexamined Patent Publication No. 2004-250277 Japanese Unexamined Patent Publication No. 2006-098284

As proposed in Patent Documents 1 and 2, various studies have been made on non-silica-based materials having a mesoporous structure containing transition metal oxides.

However, in recent years, it has been studied to use a metal oxide porous body having a mesoporous structure not only for a catalyst but also for various applications such as nanodevices. Then, there has been a demand for a metal oxide porous body having excellent structural regularity.

In view of the above problems of the prior art, one aspect of the present invention is to provide a metal oxide porous body having a mesoporous structure having excellent structural regularity.

In order to solve the above problems, in one aspect of the present invention,
It has a skeleton and mesopores with a two-dimensional hexagonal structure.
The skeleton contains an amorphous oxide containing manganese and tantalum.
Provided is a metal oxide porous body having a BET specific surface area of 100 m ² / g or more.

According to one aspect of the present invention, it is possible to provide a metal oxide porous body having a mesoporous structure having excellent structural regularity.

Explanatory drawing of two-dimensional hexagonal structure. TEM observation image of the metal oxide porous body obtained in Example 2. TEM observation image of the sample obtained in Comparative Example 1. TEM observation image of the sample obtained in Comparative Example 2.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments and does not deviate from the scope of the present invention. Can be modified and substituted in various ways.
[Metal oxide porous body]
Hereinafter, the metal oxide porous body of the present embodiment will be described.

The metal oxide porous body of the present embodiment has a skeleton portion and mesopores having a two-dimensional hexagonal structure, and the skeleton portion contains an amorphous oxide containing manganese and tantalum, and has a BET specific surface area. Can be 100 m ² / g or more.

The metal oxide porous body of the present embodiment can have a skeleton portion and mesopores having a two-dimensional hexagonal structure.

The skeleton portion of the porous metal oxide of the present embodiment can contain an amorphous oxide containing manganese and tantalum. The skeleton of the porous metal oxide of the present embodiment can also be composed of an amorphous oxide containing manganese and tantalum. According to the studies by the inventors of the present invention, a metal oxide porous body having a skeleton portion containing an amorphous oxide containing manganese and tantalum, which has not been studied in the past, is formed into a two-dimensional metal oxide porous body. It becomes easy to form mesopores of hexagonal structure. Therefore, it is possible to obtain a metal oxide porous body having a mesoporous structure having excellent structural regularity.

Regarding the metal oxide porous body of the present embodiment, for example, when electron beam diffraction is measured using a transmission electron microscope, the oxide contained in the skeleton shows a halo pattern, whereby manganese and tantalum are separated. It can be confirmed that the contained oxide is amorphous.

The two-dimensional hexagonal structure refers to a structure in which mesopores are arranged in a hexagonal manner in a cross section perpendicular to the longitudinal direction of the mesopores. FIG. 1 shows a diagram schematically showing a cross section perpendicular to the longitudinal direction of the mesohole 11. The two-dimensional hexagonal structure means a structure in which the mesopores 11 are regularly arranged in a hexagonal shape, that is, in a hexagonal shape shown by a dotted line 12, as shown in FIG. By having a two-dimensional hexagonal structure, it is possible to obtain a metal oxide porous body having a large specific surface area and a mesoporous structure having excellent structural regularity.

It should be noted that the metal oxide porous body can be subjected to low-angle X-ray diffraction measurement, and it can be determined whether or not it has a two-dimensional hexagonal structure based on the presence or absence of a diffraction peak due to the skeletal structure of the ordered arrangement of mesopores. It is also possible to determine whether the mesopores of the metal oxide porous body have a two-dimensional hexagonal structure by observation using a transmission electron microscope or the like.

The metal oxide porous body of the present embodiment preferably has a BET specific surface area of 100 m ² / g or more. This is because by setting the BET specific surface area to 100 m ² / g or more, particularly excellent properties can be exhibited in various applications such as catalysts and nanodevices.

The larger the BET specific surface area is, the more preferable it is. Therefore, the upper limit thereof is not particularly limited, but for example, 200 m ² / g or less is preferable from the viewpoint of exhibiting the mechanical strength of the metal oxide porous body.

The BET specific surface area can be calculated from the isotherm by measuring the adsorption / desorption isotherm by, for example, the nitrogen adsorption method. It is also possible to confirm that the metal oxide porous body used for the measurement has mesopores because the adsorption / desorption isotherm by the nitrogen adsorption method has a shape belonging to the IV type of IUPAC.

According to the metal oxide porous body of the present embodiment described above, it is possible to obtain a metal oxide porous body having a mesoporous structure having excellent structural regularity.
[Manufacturing method of porous metal oxide]
Next, a method for producing the metal oxide porous body of the present embodiment will be described. The above-mentioned metal oxide porous body can be produced by the method for producing the metal oxide porous body of the present embodiment. Therefore, some of the matters already described will be omitted.

The method for producing a metal oxide porous body of the present embodiment can have the following steps.

An ethanol solution preparation step of preparing an ethanol solution in which a neutral block copolymer, water, manganese chloride, and tantalum chloride are dissolved in ethanol.
A drying step of drying the solvent and water in the ethanol solution to obtain a dried product.
A firing step of firing the dried product at 450 ° C. or higher and 600 ° C. or lower in an atmosphere containing oxygen.
Then, it is preferable that each component in the ethanol solution prepared in the ethanol solution preparation step satisfies the following ratio.

The mass ratio of the neutral block copolymer to ethanol is 0.09 or more and 0.11 or less for the neutral block copolymer / ethanol.
Water / ethanol, which is the mass ratio of water to ethanol, is 0.00 or more and 0.015 or less.
Manganese chloride / ethanol, which is the mass ratio of manganese chloride to ethanol, is 0.020 or more and 0.030 or less.
The mass ratio of tantalum chloride to ethanol is 0.130 or more and 0.190 or less.

In the method for producing a metal oxide porous body of the present embodiment, a metal oxide porous body having a mesoporous structure, specifically a skeleton portion, and a mesopore having a two-dimensional hexagonal structure are oxidized by a sol-gel method. A porous body can be produced.

Conventionally, the sol-gel method has been used for the synthesis of mesoporous structure transition metal oxides and the like. Basic materials used in the synthesis of conventional mesoporous structure transition metal oxides include, for example, surfactants that are self-assembled in the process of gelation and serve as a template for mesoporous structure transition metal oxides, especially neutral. Examples include template agents such as block copolymers. In addition, organic solvents that dissolve template agents, especially alcohols, and salts of transition metals that form mesoporous structure transition metal oxides, such as chlorides, oxides, nitrates, and alkoxides, can be mentioned.

However, it has been difficult to produce a metal oxide porous body having a mesoporous structure having excellent structural regularity by the conventional method for producing a mesoporous structure transition metal oxide.

Therefore, the inventors of the present invention have made diligent studies, found a method for producing a metal oxide porous body capable of producing a metal oxide porous body having a mesoporous structure having excellent structural regularity, and completed the present invention.

Hereinafter, each step will be described in detail while explaining the reaction mechanism of the method for producing a porous metal oxide of the present embodiment.

In the ethanol solution preparation step, an ethanol solution can be prepared by mixing the components that are the raw materials of the metal oxide porous body. Specifically, in the ethanol solution preparation step, an ethanol solution can be prepared by mixing ethanol with a neutral block copolymer, water, manganese chloride, and tantalum chloride. Since ethanol and metal salts may contain water, if a sufficient amount of water can be supplied by the water contained in ethanol, etc., add water when preparing the ethanol solution. You can also not.

When the ethanol solution prepared in the ethanol solution preparation step is dried in the drying step and the solvent and water are dried, the neutral block copolymer forms micelles and is arranged in a rod shape. The rod-shaped micelles are attracted by an intramolecular force and are regularly arranged in a two-dimensional hexagonal structure.

According to the study by the inventors of the present invention, by using tantalum chloride as a tantalum source, the micelles arranged in a rod shape as described above can be regularly arranged in a two-dimensional hexagonal structure. Therefore, according to the method for producing a metal oxide porous body of the present embodiment, a metal oxide porous body having a mesoporous structure having excellent structural regularity can be produced with good reproducibility.

Further, manganese chloride and tantalum chloride contained in the ethanol solution generate hydrochloric acid when dissolved in the ethanol solution, and one of the chloride ions is replaced with ethoxydo to become a metal compound monomer. In the method for producing a porous metal oxide of the present embodiment, manganese chloride is used as a manganese source in order to obtain a metal compound monomer in this way. Then, during the aging in the ethanol solution preparation step and the drying step described later, the metal compound monomer is hydrolyzed by a small amount of water, and the hydroxyl groups generated in the monomer by hydrolysis are dehydrated and condensed between the monomers. Cross-linking reaction occurs. An inorganic phase is formed by repeating the above hydrolysis and dehydration condensation.

In this way, the timing of the formation of micelles, which are organic phases, that is, the formation of sequences of two-dimensional hexagonal structures and the formation of inorganic phases in an ethanol solution is matched, so that the matrix of inorganic phases can be formed. It becomes a state in which a self-organized organic phase is contained.

Then, a dried product that maintains the above-mentioned form is obtained by the drying step described later, and the organic phase is burned off by further carrying out the firing step described later, and the inorganic phase maintains its shape and is amorphous (amorphous). ) It becomes an oxide. Therefore, it is possible to obtain a metal oxide porous body having a mesoporous structure having excellent structural regularity.

According to the studies by the inventors of the present invention, the fact that each component in the ethanol solution is contained in a predetermined ratio with respect to ethanol is a porous metal oxide having a mesoporous structure having excellent structural regularity. It is important to get the body.

Specifically, as described above, it is a value obtained by dividing the mass ratio of the neutral block copolymer to ethanol, that is, the mass ratio of the neutral block copolymer added to the ethanol solution by the mass ratio of ethanol. The block copolymer / ethanol is preferably 0.09 or more and 0.11 or less.

This is because the ratio of the organic phase to the inorganic phase can be sufficiently increased by setting the neutral block copolymer / ethanol to 0.09 or more, and the intramolecular force of the distance between adjacent rod-shaped micelles can be sufficiently increased. This is because it can work sufficiently and self-arrange into a two-dimensional hexagonal structure. When the neutral block copolymer / ethanol is set to less than 0.09, a metal oxide porous body having mesopores but not a two-dimensional hexagonal structure may be formed, which is not preferable.

Further, by setting the mass ratio of the neutral block copolymer / ethanol to 0.11 or less, a sufficient amount of the inorganic phase can be supplied between the rod-shaped micelles self-arranged in the two-dimensional hexagonal structure. It can be a metal oxide porous body having a desired skeletal structure.

Further, it is preferable that water / ethanol, which is the mass ratio of water to ethanol, that is, the mass ratio of water added to the ethanol solution divided by the mass ratio of ethanol, is 0.00 or more and 0.015 or less.

This is because by setting water / ethanol to 0.015 or less, it is possible to suppress the formation of hydroxide for one of the chloride ions and more reliably replace it with ethoxide to obtain a metal compound monomer. Is. Therefore, a sufficient amount of the inorganic phase can be supplied between the rod-shaped micelles to form a metal oxide porous body having a mesoporous structure. If the amount of water / ethanol exceeds 0.015, mesopores may not be formed and only an aggregate of ordinary nanoparticles may be formed, which is not preferable.

The water is not limited to the water added when preparing the ethanol solution, and it is preferable that water / ethanol satisfies the above range, for example, including water contained in ethanol and water contained in a metal salt.

Manganese chloride / ethanol, which is the mass ratio of manganese chloride to ethanol, that is, the mass ratio of manganese chloride added to the ethanol solution divided by the mass ratio of ethanol, is preferably 0.020 or more and 0.030 or less. Further, it is preferable that tantalum chloride / ethanol, which is the mass ratio of tantalum chloride to ethanol, that is, the mass ratio of tantalum chloride added to the ethanol solution divided by the mass ratio of ethanol, is 0.130 or more and 0.190 or less. ..

By setting the manganese chloride / ethanol to 0.020 or more and the tantalum / ethanol chloride to 0.130 or more, a sufficient amount of the inorganic phase can be supplied between the arranged rod-shaped micelles. Therefore, after the firing step, the skeleton structure cannot be maintained and mesopores are not formed, so that it can be more reliably prevented from forming an aggregate of ordinary nanoparticles.

By setting manganese chloride / ethanol to 0.030 or less and tantalum chloride / ethanol to 0.190 or less, the ratio of the inorganic phase to the organic phase can be prevented from becoming excessively large, and the distance between adjacent rod-shaped micelles can be prevented. This is because the intermolecular force can be fully exerted and self-arranged into a two-dimensional hexagonal structure. Therefore, after the firing step, it is possible to surely prevent the metal oxide porous body from which the mesopores are formed but the two-dimensional hexagonal structure cannot be obtained.

The neutral block copolymer is not particularly limited, but is a triblock copolymer of polypropylene oxide (PO) chain-polyethylene oxide (EO) chain-polypropylene oxide (PO) chain ((PO) _x (EO) _y (PO) _x . ) Is preferable.

The polypropylene oxide (PO) chain is represented by (CH ₂ CH (CH ₃ ) O) _x and is also referred to as “PO”. Further, the polyethylene oxide (EO) chain is represented by (CH ₂ CH ₂ O) _y and is also referred to as “EO”.

Although x and y in the above formula are not particularly limited, x is preferably 5 or more and 110 or less, and more preferably 15 or more and 20 or less. Further, y is preferably 15 or more and 70 or less, and more preferably 50 or more and 70 or less.

Examples of such triblock copolymers include (EO) ₅ (PO) ₇₀ (EO) ₅ , (EO) ₁₃ (PO) ₃₀ (EO) ₁₃ , (EO) ₂₀ (PO) ₃₀ (EO) ₂₀ , (EO) ₂₆ (PO) ₃₉ (EO) ₂₆ , (EO) ₁₇ (PO) ₅₆ (EO) ₁₇ , (EO) ₁₇ (PO) ₅₈ (EO) ₁₇ , (EO) ₂₀ (PO) ₇₀ (EO) ₂₀ , (EO) ₈₀ (PO) ₃₀ (EO) ₈₀ and the like can be mentioned. In particular, (EO) ₂₀ (PO) ₇₀ (EO) ₂₀ can be preferably used.

Then, in the method for producing a metal oxide porous body of the present embodiment, a drying step and a firing step can be further carried out.

In the drying step, the solvent in the ethanol solution and water can be dried to obtain a dried product. Examples of the solvent include ethanol and the like.

The drying conditions at this time are not particularly limited, but it is preferable not to proceed with the drying rapidly from the viewpoint of enhancing the structural regularity of the obtained metal oxide porous body. Therefore, it is preferable that the drying in the drying step is carried out in an environment of, for example, 20 ° C. or higher and 80 ° C. or lower. Further, it is preferable to arrange a lid such as a wrap in the opening of the container containing the ethanol solution and to make a plurality of holes in the lid to adjust the drying speed.

In the firing step, the dried product obtained in the drying step can be fired in an atmosphere containing oxygen, for example, in an atmospheric atmosphere at 450 ° C. or higher and 600 ° C. or lower.

According to the method for producing a metal oxide porous body of the present embodiment described above, by using a predetermined ethanol solution, a metal oxide porous body having a mesoporous structure having excellent structural regularity can be stably produced with good reproducibility. Can be manufactured.

Specific examples will be given below, but the present invention is not limited to these examples.
(About evaluation method)
The following evaluations were performed on the samples prepared in the following examples and comparative examples.
(1) Nitrogen adsorption / desorption isotherm shape, BET specific surface area For the samples prepared in each Example and Comparative Example, a nitrogen adsorption method using a specific surface area / pore distribution measuring device (Beckman Coulter model: SA3100). The adsorption and desorption isotherms were measured by the above-mentioned method, and it was investigated whether the isotherms had the type IV shape of IUPAC, which was observed when the isotherms had a mesoporous structure. If it has the IV type of IUPAC, enter "IUPAC IV type" in the "Nitrogen adsorption / desorption isotherm shape" column of Table 1, and in other cases, enter x. ing. If the sample has the IV type of IUPAC, the sample will have mesopores.

In addition, the specific surface area by the BET method was estimated from the isotherms obtained at this time. Table 1 shows the evaluation results in the column of "BET specific surface area".
(2) Presence or absence of low-angle X-ray diffraction peaks due to the skeletal structure of the ordered arrangement of mesopores For the samples prepared in each Example and Comparative Example, an X-ray diffractometer (Rigaku model: RINT2100, CuKα ray) was used. Low-angle X-ray diffraction measurements were performed using this to examine the presence or absence of diffraction peaks due to the skeletal structure of the ordered arrangement of mesopores. When such a diffraction peak is observed, the mesopore has a two-dimensional hexagonal structure. Therefore, in the sample in which the column of "presence or absence of low-angle X-ray diffraction peak due to the skeletal structure of the ordered arrangement of mesopores" is "Yes" in Table 2, the mesopores have a two-dimensional hexagonal structure. It will be. The sample in which the column is "None" cannot confirm the diffraction peak due to the skeletal structure of the ordered arrangement of the mesopores, and does not have the mesopores arranged in the two-dimensional hexagonal structure.
(3) Presence or absence of mesopores having a two-dimensional hexagonal structure by TEM observation For the samples obtained in each Example and Comparative Example, a transmission electron microscope (TEM: Transmission Electron Microscope) (JEOL JEM2010). The formation of mesopores was also observed. In Table 2, the sample in which "presence or absence of mesopores having a two-dimensional hexagonal structure by TEM observation" is "yes" indicates that the mesopores have a two-dimensional hexagonal structure when observed by TEM. It means that it was confirmed. A sample whose column is "None" cannot be confirmed to have a two-dimensional hexagonal structure when observed by TEM, and does not have mesopores arranged in the two-dimensional hexagonal structure. ..

In addition, electron diffraction revealed that all oxides showed a halo pattern, confirming that they had an amorphous structure.
[Example 1]
The metal oxide porous body was produced and evaluated by the following procedure.

10 g of ethanol (super-dehydrated, 99.5%) was weighed in a Teflon (registered trademark) beaker as a solvent. Next, the neutral block copolymer P123 (manufactured by Aldrich) represented by HO (CH ₂ CH ₂ O) ₂₀ (CH ₂ CH (CH ₃ ) O) ₇₀ (CH ₂ CH ₂ O) ₂₀ H in the above ethanol was added. ) 1 g was added and stirred with a magnetic stirrer to completely dissolve.

Then, manganese chloride and tantalum chloride (manufactured by High Purity Chemical Co., Ltd.) were added to a solution in which a neutral block copolymer was dissolved in ethanol, and the mixture was stirred and completely dissolved to prepare an ethanol solution (ethanol solution preparation). Process).

As manganese chloride, manganese chloride (II) anhydride (STREM CHEMICALS, INC) was used.

Mass ratio of neutral block copolymer, water, manganese chloride, tantalum chloride in ethanol solution to ethanol, specifically neutral block copolymer / ethanol, water / ethanol, manganese chloride / ethanol, tantalum chloride / ethanol Is shown in Table 1. The amount of water in calculating water / ethanol in Table 1 is derived from the water in ethanol. The water in ethanol is calculated from the purity and is calculated as 0.5%.

The prepared ethanol solution was transferred to a beaker having a diameter of 100 mm, covered with a wrap having 20 small holes evenly with a needle so that the solvent volatilized appropriately, and placed in a constant temperature bath at 40 ° C. and dried for 1 week (drying). Process).

The dried product obtained in the drying step was peeled off from the petri dish, placed in a crucible, set in an electric furnace, heated in the air at 550 ° C. for 30 hours, and calcined to obtain an oxide (calcination step).

The above-mentioned evaluation was carried out for this oxide. The results are shown in Table 2.

In addition, the obtained metal oxide porous body was quantitatively analyzed by ICP (Inductively Coupled Plasma) emission spectroscopy using an ICP emission spectrometer (model: ICPS-800 manufactured by Shimadzu Corporation), and manganese and tantalum were almost as prepared. It was confirmed that the composition ratio was set.
[Examples 2 to 5]
In the ethanol solution preparation step, a metal oxide porous body was prepared in the same manner as in Example 1 except that the mass ratio of each raw material was set to the value shown in Table 1, and the evaluation described above was performed. rice field.

In Example 3, as manganese chloride, manganese (II) chloride tetrahydrate (special grade, Wako Pure Chemical Industries, Ltd.) was used instead of manganese (II) chloride anhydride. Therefore, the amount of water when calculating water / ethanol is calculated by adding the water in ethanol and the water derived from manganese (II) chloride tetrahydrate.

The evaluation results are shown in Table 2.

In addition, the obtained porous metal oxide was quantitatively analyzed by ICP emission spectroscopy, and it was confirmed that the composition ratios of manganese and tantalum were almost as prepared.
[Comparative Example 1 to Comparative Example 5]
In the ethanol solution preparation step, a metal oxide porous body was prepared in the same manner as in Example 1 except that the mass ratio of each raw material was set to the value shown in Table 1, and the evaluation described above was performed. rice field.

In Comparative Example 3, manganese chloride (II) tetrahydrate (special grade, Wako Pure Chemical Industries, Ltd.) was used as manganese chloride instead of manganese (II) chloride anhydride (STREM CHEMICALS, INC). Ion-exchanged water was added dropwise to prepare an ethanol solution. Therefore, the amount of water when calculating water / ethanol is calculated by adding up the water in ethanol, the water derived from manganese (II) chloride tetrahydrate, and the dropped ion-exchanged water. There is.

The evaluation results are shown in Table 2.

In addition, the obtained porous metal oxide was quantitatively analyzed by ICP emission spectroscopy, and it was confirmed that the composition ratios of manganese and tantalum were almost as prepared.

表２に示したように、実施例１～実施例５では、骨格部と、二次元ヘキサゴナル構造のメソ孔とを有し、骨格部は、マンガンとタンタルとを含む非晶質の酸化物を含有し、ＢＥＴ比表面積が１００ｍ^２／ｇ以上である金属酸化物多孔体を得られることが確認できた。

As shown in Table 2, Examples 1 to 5 have a skeleton portion and mesopores having a two-dimensional hexagonal structure, and the skeleton portion contains an amorphous oxide containing manganese and tantalum. It was confirmed that a metal oxide porous body containing and having a BET specific surface area of 100 m ² / g or more could be obtained.

By mixing each component in the ethanol solution so as to have a predetermined mass ratio, the formation of micelles, which are organic phases, self-assembly, that is, the formation of a two-dimensional hexagonal structural sequence occurs in the ethanol solution. This is probably because a sufficient inorganic phase could be supplied between the organic phases. Then, a dried product maintaining the above-mentioned form is obtained by the drying step, and the organic phase is burned off by further carrying out the firing step, and the inorganic phase maintains its shape to form an amorphous oxide. Therefore, it is considered that a metal oxide porous body having a meso-porous structure with excellent structural regularity could be obtained.

Further, from the results of TEM observation, in Examples 1 to 5, mesopores having a two-dimensional hexagonal structure having a pore diameter of about 3.9 nm to 4.5 nm and a wall thickness of 3.3 nm to 3.8 nm were formed. It was also confirmed that it was done.

As an example of the TEM photograph, FIG. 2 shows the TEM photograph of Example 2. As shown in FIG. 2, it was confirmed that a mesoporous metal oxide porous body having excellent structural regularity in which the mesopores 21 were arranged so as to have a two-dimensional hexagonal structure was obtained. Although only the TEM image of Example 2 is shown here, it has been confirmed that the other Examples 1 and 3 to 5 have the same structure.

On the other hand, in Comparative Example 1, a mesopore was formed, but a two-dimensional hexagonal structure was not observed. It is considered that this is because the mass ratio of the metal chloride in the ethanol solution was large, and the micelles of the surfactant were not regularly arranged due to the intramolecular force.

The TEM observation image of the sample obtained in Comparative Example 1 is shown in FIG. As shown in FIG. 3, the mesopores were confirmed, but the structural regularity could not be confirmed.

In Comparative Example 2, the shape of the nitrogen adsorption isotherm is not IUPAC type IV and no mesopores are formed. It is considered that this is because the mass ratio of the metal chloride in the ethanol solution was small, and the skeleton of the inorganic phase disappeared when the micelles were burned off during firing.

The TEM observation image of the sample obtained in Comparative Example 2 is shown in FIG.

The sample obtained in Comparative Example 3 had a small specific surface area and the shape of the nitrogen adsorption isotherm was not IUPAC type IV. It is considered that this is because the amount of water in the ethanol solution was large, so that the metal chloride was hydrolyzed too quickly and a hydroxide precipitate was formed.

The sample obtained in Comparative Example 4 had an IUPAC type IV nitrogen adsorption isotherm, and it was confirmed that mesopores were formed. However, from the low-angle X-ray diffraction and TEM observation results, it was confirmed that the mesopores were not arranged in the two-dimensional hexagonal structure. This is because the mass ratio of the neutral block copolymer in the ethanol solution was small and the mass ratio of the amount of metal chloride was relatively large, so that the micelles of the surfactant were not regularly arranged by the intramolecular force. It can be considered that it is due to.

In the sample obtained in Comparative Example 5, it was confirmed that the shape of the nitrogen adsorption isotherm was not IUPAC type IV and no mesopores were formed. This is because the mass ratio of the neutral block copolymer in the ethanol solution is too large and the mass ratio of the metal chloride is relatively small, and the skeleton of the inorganic phase disappears when the micelles are burned off during firing. It seems that this is due to the fact that it has been done.

11, 21 meso holes

Claims (3)

It has a skeleton and mesopores with a two-dimensional hexagonal structure.
The skeleton contains an amorphous oxide containing manganese and tantalum.
A metal oxide porous body having a BET specific surface area of 100 m ² / g or more. An ethanol solution preparation step of preparing an ethanol solution in which a neutral block copolymer, water, manganese chloride, and tantalum chloride are dissolved in ethanol, and
A drying step of drying the solvent and water in the ethanol solution to obtain a dried product,
It has a baking step of baking the dried product at 450 ° C. or higher and 600 ° C. or lower in an atmosphere containing oxygen.
In the ethanol solution,
The mass ratio of the neutral block copolymer to the ethanol is 0.09 or more and 0.11 or less for the neutral block copolymer / ethanol.
Water / ethanol, which is the mass ratio of the water to the ethanol, is greater than 0.00 and 0.015 or less.
Manganese chloride / ethanol, which is the mass ratio of the manganese chloride to the ethanol, is 0.020 or more and 0.030 or less.
A method for producing a metal oxide porous body in which tantalum chloride / ethanol, which is the mass ratio of tantalum chloride to ethanol, is 0.130 or more and 0.190 or less. The method for producing a metal oxide porous body according to claim 2, wherein the neutral block copolymer is a triblock copolymer of polypropylene oxide (PO) chain-polyethylene oxide (EO) chain-polypropylene oxide (PO) chain.

Images