JPH10130002A - Three dimensional mesh like metal oxide and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metal oxide having large surface area and small pressure loss, capable of treating a reaction product with a small space velocity and useful for a catalyst (carrier) by constituting so as to incorporate at least one metal oxide and to form into a three dimensional mesh like state. SOLUTION: This three dimensional mesh like metal oxide is constituted so as to incorporate one or more metal oxide preferably selected from group IA-IVB metals (e.g. oxide of Al) and to form into the three dimensional mesh like state preferably having 1-100μm, particularly 10-50μm diameter of column, the length of column 1-1000 times, particularly 10-100 times the diameter of column and 10-98%, particularly 50-90% whole porosity. The metal oxide is preferably a porous body having 10-500m<2> /g surface area. The three dimensional mesh like metal oxide is produced by forming a sol containing the metal of a raw material of the metal oxide material, charging the sol like material in a vessel under a high pressure, discharging to the atmosphere by passing through a hole having a pressure reducing section under a spontaneous pressure or a certain pressure, vaporizing a solvent to form the metal oxide into the three dimensional mesh like state and next, drying and firing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a metal oxide useful as a catalyst or a carrier for a metal catalyst. More specifically, the present invention provides a metal oxide having a novel morphology and a method for producing the metal oxide.

[0002]

2. Description of the Related Art Aluminum oxide, silicon oxide,
Metal oxides such as titanium oxide are widely used as catalysts or catalyst carriers. As the form of the metal oxide, a granular form, a ring form, a honeycomb form, a long fiber and a short fiber, a cloth form knitted with a long fiber, and a mat form collecting short fibers are known.

When a metal oxide of such a form is used as a catalyst or a catalyst carrier, for example, when the most common granular or ring-shaped metal oxide is used in a flow-type fixed bed, the pressure loss is large because of its shape. Therefore, there is a problem that the space velocity cannot be increased and the processing capacity is limited. Another problem is that the metal oxides are gradually damaged due to contact with each other.

[0004] In order to solve the above-mentioned problem, a catalyst carrier in which a metal oxide is formed into a monolith honeycomb shape is used. However, since such a form is obtained by forming a honeycomb from a slurry of a metal oxide precursor by extrusion molding and performing sintering, a mold is required, and the production cost increases. Further, when the honeycomb structure is employed, the ratio of the amount of the catalyst actually used in the reaction to the whole volume is considerably small, and there is a disadvantage that a large reactor is required.

On the other hand, when a metal oxide fiber molded into a woven or nonwoven fabric is used, the cost of the metal oxide fiber increases, and the composition that can be used to give the fiber form is limited. Therefore, problems such as durability also arise.

[0006]

SUMMARY OF THE INVENTION The present invention provides a metal oxide having a large specific surface area, a small pressure loss, and a form capable of treating a reactant at a high space velocity, and a method for producing the same. With the goal.

[0007]

Means for Solving the Problems As a result of diligent research by the present inventors, it has been found that the above-mentioned problems can be solved by molding a porous metal oxide into a three-dimensional network, and the present invention has been completed. .

[0008] That is, the gist of the present invention is a three-dimensional network metal oxide containing at least one type of metal oxide and formed in a three-dimensional network.

The three-dimensional network metal oxide of the present invention is preferably a metal belonging to Groups 1A to 4B, specifically, silicon, aluminum, titanium, zirconium, vanadium,
It is made of at least one metal oxide selected from the group consisting of copper, iron, chromium, cobalt, tin, zinc, niobium, and tungsten. The ratio between the metal and oxygen in the metal oxide is not particularly limited, and may be any ratio that can exist as a metal oxide, but it is preferable that the two be in a stoichiometric ratio. In addition, when the metal oxides are mixed and used, the mixing ratio is not particularly limited.

[0010] Metal oxide constituting the three-dimensional mesh-like metal oxide of the present invention is a BET specific surface area measured by the nitrogen adsorption method, 500m ² / g from 10 m ² / g, more preferably from 30 m ² / g 250 meters It is preferable that the porous body is ² / g.

The three-dimensional mesh-like metal oxide of the present invention has a column having a diameter of 1 to 100 μm, preferably 10 to 50 μm, and a column length, that is, a distance between a contact point of each column and a contact point of 10 mm in diameter.
What is 100 times is preferably used.

In the three-dimensional network metal oxide of the present invention, the ratio (porosity) of the portion excluding the metal oxide to the entire volume is preferably 10% to 98%, particularly 50 to 90%. preferable.

The three-dimensional network metal oxide of the present invention can be used alone as a catalyst, but may support another metal. The metal supported on the three-dimensional network metal oxide of the present invention is not particularly limited as long as it is used as a catalyst in a chemical reaction. A transition metal usually used as a catalyst, particularly a metal belonging to Group 8 of the circumferential discipline is preferred. Particularly preferred are platinum, lead, rhodium and nickel. Depending on the purpose, the metal may be supported alone.
More than one type may be supported, and when two or more types are supported, the ratio of each metal is not particularly limited. The total amount of the metal to be supported is from 0.1 part by weight to 1 part by weight with respect to the metal oxide.
0 parts by weight, preferably 0.5 to 5 parts by weight.

The metal oxide of the present invention is particularly preferably used as a catalyst or a catalyst carrier. That is, since the three-dimensional network metal oxide of the present invention has a large specific surface area and a small pressure loss, it can treat a reactant at a large space velocity.

The present invention further provides a method for easily producing the three-dimensional network metal oxide. That is, the present invention prepares a sol containing a metal oxide precursor, puts the sol in a container under high pressure, and places it in the atmosphere through a hole having a pressure drop chamber under autogenous pressure or under pressure. A method for producing a three-dimensional network-like metal oxide, comprising the steps of: evaporating a solvent, forming a three-dimensional network immediately thereafter, and drying and firing the solvent.

Alumina, silicate, titania and the like are generally known as metal oxides often used as catalysts or catalyst carriers. Examples of general methods for producing metal oxides include, for example, “Relationship between preparation of metal oxides and composite oxides, physical properties, structure, catalysis, and inorganic materials”
As described in Kobe Tabe, published by Kodansha, etc., a dry method, a wet method and the like are known. In the present invention, a metal oxide is produced based on a wet method.

The metal-containing sol used in the method of the present invention comprises a metal compound which can form a sol-like substance and is converted into an oxide by firing, and a solvent, such as a metal alkoxide, (M (OR) n
(M is a metal, OR is an alkoxyl group, n represents the oxidation number of the metal) metal organic compounds such _{as, MX n OH m · H 2} O (M is a metal, X is a halogen, m + n is the oxidation number of the metal) metal such as Examples thereof include those prepared by hydrolyzing a salt or the like.

In the case of preparing a sol from a metal alkoxide, if water is added to the metal alkoxide and mixed, the alkoxide reacts with water to hydrolyze, and the OR group is changed to an OH group, which is polymerized to polymerize the sol. Becomes

As the metal alkoxide, an extremely large number of types can be used by appropriately selecting the metal and R. R represents methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-
Particularly preferred are lower alkyl groups such as butyl. Further, a composite metal alkoxide containing two or more metals may be used.

In order to obtain a sol from a basic metal salt, the basic metal salt may be dissolved in water or an organic solvent, and an organic polyacid may be added thereto. The organic polyhydric acid used herein refers to an organic compound having two or more carboxyl groups,
Generally, those not polymerized are preferred. Saturated aliphatic carboxylic acids such as oxalic acid, malonic acid, succinic acid, citric acid, malic acid and tartaric acid, unsaturated aliphatic carboxylic acids such as maleic acid and fumaric acid, and aromatic carboxylic acids such as terephthalic acid and isophthalic acid And especially having 2 to 3 carboxyl groups and 1 to 2 hydroxyl groups per molecule.
Citric acid, malic acid, tartaric acid are preferred. The organic polyacid may be used alone or in combination of two or more.

As the solvent used for forming the sol,
Water, alcohol, ester, ether, ketone, nitrile, amide, sulfur dioxide, carbon dioxide, nitromethane,
Aromatic hydrocarbons such as aromatic hydrocarbons such as benzene and toluene, butane, pentane, hexane, heptane and octane, or isomers and homologs thereof, alicyclic hydrocarbons such as cyclohexane, methylene chloride, and carbon tetrachloride , Chloroform, 1,1-dichloro-2,2 fluoroethane,
Examples thereof include, but are not limited to, halogenated hydrocarbons such as 1,2-dichloro-1,1-difluoroethane, methylene chloride, and fluorocarbons.

The metal oxide is dissolved in the above solvent and concentrated to form a sol. To obtain the desired properties, the sol solution is further concentrated under high temperature and pressure. The conditions for obtaining a sol having an appropriate viscosity vary depending on the type of metal and solvent, but it is preferable that concentration be performed at a temperature near the boiling point of the solvent. The pressure is not particularly limited as long as it is a pressure at which a liquid is concentrated to obtain a sol.

In producing the metal oxide precursor sol,
Surfactants, pigments, stabilizers and the like may be added as long as the effects of the present invention are not impaired.

The sol-form metal oxide precursor used in the present invention has a viscosity of 100 to 1,000,000 centipoise, preferably 1 to 100,000 centipoise.
Let it be 100 to 30,000 centipoise. If the viscosity of the sol is too high, it is difficult to release the sol from the nozzle by pressure, while the low viscosity means that the concentration of the metal oxide precursor is low, and the productivity decreases. It also affects the structure, strength, and the like of the formed three-dimensional structure.

For example, when preparing an alumina sol, an organic polyacid is added little by little while stirring a basic aluminum salt aqueous solution and mixed, then concentrated to obtain a sol, or an aluminum alkoxide, alkanolamine compound The sol may be obtained by mixing a magnesium compound with an organic solvent, hydrolyzing and concentrating the mixture.

The basic aluminum salt is represented by the formula (Al
₂ (OH) nCl ₆ -n) m (3 ≦ n ≦ 5, m ≦ 10), a basic aluminum chloride represented by the formula (Al ₂ (OH) n (Lac) ₆ -n) m
And basic aluminum lactate represented by (3 ≦ n ≦ 5, m ≦ 10). When preparing a sol using a basic aluminum salt, a sol containing an organic polyacid is prepared. Such a sol can be obtained by, for example, adding and mixing an organic polyhydric acid little by little while stirring a basic aluminum salt aqueous solution, and then concentrating the mixture.

At this time, the concentration of the basic aluminum salt is preferably 80% by weight or less, particularly preferably 50 to 70% by weight. The amount of the organic polyacid is 0.1% by weight or more based on the amount of aluminum in the aqueous solution, and a sufficient effect is recognized, and 1 to 5% by weight is particularly preferable.

When the organic polyacid is added to the basic aluminum salt aqueous solution, it is preferable to add the basic aluminum salt aqueous solution little by little in consideration of the swelling of the organic polyacid. The temperature for mixing is not particularly limited. For example, citric acid can be a sufficiently uniform solution at room temperature (about 10 to 40 ° C.).

The pressure at the time of concentration is not particularly limited, and the pressure may be normal pressure. The temperature at the time of concentration is preferably 80 ° C. or lower, particularly preferably at 40 to 60 ° C. Is preferred. The temperature at this time is 8
If the temperature is 0 ° C. or higher, gelation proceeds rapidly from the solution surface, and it becomes difficult to obtain a sol stably, such as precipitation of solids. On the other hand, if the concentration temperature is low, the progress of gelation is slowed down, which is not preferable in view of workability. In this manner, the sol may be concentrated to a viscosity of about 1 to 100 poise, preferably 1 to 20 poise.

When a sol is prepared using an aluminum alkoxide, the alkanolamine is added to promote stable hydrolysis and to effectively mix the aluminum alkoxide with an organic solvent or a mixed organic solvent. Examples of the alkanolamine include monomethanolamine, monoethanolamine, mono-n-propanolamine, mono-iso-propanolamine, trimethanolamine, triethanolamine, tri-n-propanolamine, and tri-iso-propanolamine. No. The amount of the active hydrogen is preferably in the range of 0.5 to 2.5 mol, more preferably 0.8 to 2.0 mol, per 1 mol of the aluminum alkoxide. When the amount of the alkanolamine is less than 0.5 mol, the hydrolysis rate becomes high, and a preferable sol cannot be obtained due to precipitation of a precipitate. If it exceeds 2 mol, a sol having an appropriate viscosity cannot be obtained, and it is difficult to maintain the form.

In this case, a magnesium compound is added to increase the stability of the sol. When a mixed organic solvent is used, the addition of a magnesium compound is unnecessary. As the magnesium compound, magnesium nitrate, magnesium carbonate, magnesium sulfate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, trimagnesium phosphate, magnesium fluoride, magnesium bromide, magnesium chloride, magnesium iodide, magnesium hydroxide,
Examples include inorganic magnesium compounds such as magnesium phosphinate and magnesium silicate, and organic magnesium compounds such as magnesium acetate, magnesium citrate, magnesium lactate, magnesium stearate, and magnesium oxalate. When a magnesium compound is added, it is preferable that the magnesium compound is added so that the weight ratio of magnesium oxide / alumina at the time of firing is 0.1 to 10%, particularly 0.5 to 5%. preferable.

As the organic solvent, alcohols represented by methanol, ethanol, n-propanol, n-butanol, iso-butanol, sec-butanol and mixed organic solvents thereof are particularly preferably used. The amount of the organic solvent or the mixed organic solvent to be used is preferably 5 to 30 mol, and particularly preferably 8 to 25 mol, per 1 mol of the aluminum alkoxide. As the mixed organic solvent, two or more of the above organic solvents are mixed, but the organic solvent having the highest content in the mixed organic solvent (main solvent) has a higher boiling point than the main solvent as the other organic solvent. It is preferable to use a solvent. For example, when iso-propanol (boiling point 82 ° C.) is used as the main solvent, sec-butanol (boiling point 99 ° C.) is used as another organic solvent. The mixing ratio (molar ratio) is preferably from 0.1 to 0.8, and particularly preferably from 0.2 to 0.5.

The mixture is heated and concentrated to obtain a sol. Heating is preferably performed at a temperature near the boiling point of a single organic solvent, or at a temperature near the boiling point of the main solvent of a mixed organic solvent. At this time, the viscosity of the solution increases due to concentration with a single organic solvent, and the gelation tends to progress rapidly in a region where the viscosity can be spun, but the presence of another organic solvent having a high boiling point in a mixed organic solvent Thereby, the progress of gelation is suppressed, and a stable sol can be obtained.

The obtained aluminum alkoxide-containing solution is hydrolyzed to obtain a sol. The hydrolysis may be performed, for example, by adding water to hydrolyze the aluminum alkoxide. At this time, the amount of water to be added is preferably in the range of 0.5 to 2 mol, more preferably in the range of 0.8 to 1.5 mol, per 1 mol of aluminum alkoxide. If less than 0.5 mole,
It is not preferable because it is difficult to maintain the form of the three-dimensional network structure precursor. When the amount is more than 2 mol, the hydrolysis rate is increased, so that a powdery precipitate is easily precipitated, and the obtained sol is further gelled, and the workable time is shortened. It is not preferable considering the properties.

In addition to the above, for example, in the case of a porous silicate which is a commonly used porous metal oxide, Na _{2 is used.
O · x SiO 2 · y H} 2 O and water glass having a general formula of (x = 1 to 4) was neutralized with sulfuric acid and hydrochloric acid, or if you get a hydrogel through a silica sol having a composition of polysilicic acid. Further, any other known method may be used to obtain a gel of a metal oxide precursor.

The sol of the metal oxide precursor obtained as described above is spouted from a high temperature and high pressure condition through a hole having a pressure drop chamber. The pressure drops rapidly by passing through the pressure drop chamber, causing phase separation. Thereafter, the metal oxide precursor is blown into the atmosphere, and is released in a fibrous form. A three-dimensional structure is obtained by depositing fibrous metal oxide on a plate placed at an appropriate distance. In order to make the metal oxide precursor a high temperature and high pressure condition, a sol concentrated to an appropriate viscosity is charged into a pressure vessel, and then the sol may be heated to a high temperature and a high pressure. May be concentrated by heating.

The release is carried out under the autogenous pressure or the pressurized pressure through a pressure drop chamber, and once released into a two-layer state, and then released into the atmosphere. By adjusting the pressure at the time of release, it is possible to change the three-dimensional network structure formed. The volume of the pressure drop chamber is preferably 1 to 100 cc, more preferably 2 to 50 cc. The diameter (D) of the nozzle at the time of jetting is 0.1 to 2.0 mm
φ is preferable, and 0.3 to 1.0 mmφ is particularly preferable. At this time, the ratio between the length (L) of the hole and the diameter (L / D) is 1
6 is preferable, and it is particularly preferable to set it to 1 to 3. If the pressure at the time of discharge is increased, the fibrous metal explosively spreads, and the network structure becomes coarse. Conversely, when the pressure is low, the structure becomes dense. However, the pressure desired for production is at least 40 kg / cm ² , preferably 40 to 150 kg / cm ² , more preferably 80 to 12 kg / cm ² .
It is 0 kg / cm ² .

Once the sol is released, the solvent evaporates,
The metal oxide precursor becomes fibrous. The released fibrous metal oxide precursor is spread in the width direction by an impact plate and deposited on a movable wire mesh sheet. The sheet is moved during deposition so that the fibers to be deposited have the desired network. The thickness may be set according to the intended use, but is preferably 1 mm or more from the viewpoint of easy handling.

The obtained three-dimensional network structure of the metal oxide precursor is fired to produce a metal oxide. As described above, the solvent evaporates during normal release, and thus the drying step may be performed as needed. Heating, drying, and baking may be performed by any conventionally known method.Specifically, for example, a solvent or other organic substance contained therein is heated by heating in air or an inert gas such as nitrogen or argon to carbonize the contained solvent or other organic matter. Further, the carbonized organic component may be burned by heating in the presence of oxygen, preferably in air, to remove the carbonized organic component and to convert the metal oxide precursor to a metal oxide. The obtained metal oxide may be further fired in a vacuum or under a hydrogen atmosphere.

The specific surface area, pore structure, and the like can be controlled by the firing temperature. The preferred firing temperature varies depending on the type of the metal oxide.
The temperature is set to 00 ° C, more preferably 700 to 900 ° C. If the firing temperature is higher than 1100 ° C., α-phase alumina precipitates,
The specific surface area decreases. On the other hand, when the firing temperature is lower than 500 ° C., the organic component remains as residual carbon in the three-dimensional network metal oxide, which is not preferable. The firing time is not particularly limited as long as the organic components are sufficiently removed and alumina is formed, and is usually 1 to 5 hours.

In order to carry the metal serving as a catalyst on the obtained metal oxide on the metal oxide of the present invention, the metal oxide precursor may be mixed with a salt containing the metal carried on the sol. The obtained three-dimensional network structure may be supported by any of an impregnation method, a precipitation method, and an ion exchange method.

When the metal oxide precursor is mixed with the sol, the above-mentioned treatment may be carried out by mixing the metal salt to be carried with the sol.

As a general method of supporting a metal on the obtained metal oxide porous material, an impregnation method, a precipitation method, and an ion exchange method are known. Although it may be supported by any method, the impregnation method is most preferable. The impregnation method is a method in which a catalytically active component is immobilized on the inner wall of pores by immersing in a solution containing a metal component for supporting a formed metal oxide porous carrier, and performing an activation treatment such as drying, calcination and reduction. There are known an evaporation to dryness method, an adsorption method, a dry impregnation method, and a spray method. The evaporation to dryness method is a method in which a carrier is immersed in a solution containing a metal component, and then the solvent is evaporated with stirring to attach a solute to the carrier. In the adsorption method, after a carrier is immersed in a solution containing a metal component, the solution is separated by filtration. The amount supported is determined by the solution concentration and the pore volume. This includes the case where the carrier is adsorbed in an amount equal to or less than the saturated adsorption amount of the carrier, the case where the carrier is immersed in a solution containing a metal component greater than or equal to the saturated adsorption amount of the carrier for a long time, and the carrier is adsorbed to equilibrium. In some cases, a solution containing a volume of a metal component is added and all of the solution is absorbed. In the dry impregnation method, after the carrier is evacuated and the gas in the pores is removed, a solution corresponding to the pore volume is added little by little with a burette or the like. The dropping is continued until the carrier surface is uniformly wet and no excess solution is present. The spray method is a method of keeping a carrier in a dry state in an evaporator or the like and spraying a solution containing a metal component.

Other precipitation methods: In general, a solution containing a metal component is brought into contact with a precipitant solution to form a precipitate such as a hydroxide or a carbonate, followed by filtration, washing with water, drying, molding and firing. Is a method of supporting a metal component by performing
A metal serving as a catalyst to be supported is mixed with a metal oxide precursor sol, molded into a three-dimensional network, and calcined; and an ion exchange method is performed. You may use the method of carrying by an ion exchange reaction.

[0045]

The present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the examples.

Example 1 10 mol of aluminum isopropoxide, 150 mol of isopropanol and 10 mol of water were mixed at 60 ° C. for 1 hour. Next, the temperature was raised to 80 ° C., and the mixture was heated and concentrated for 6 hours to prepare a sol. 30% by weight of carbon dioxide gas was injected into the sol as a pressure increasing agent. Temperature 3
When the pressure reached 0 ° C. and the pressure reached 100 kg / cm ² , the sol was discharged from a nozzle having an orifice diameter of 0.75φ.
It was deposited on a stainless steel plate at a position 50 mm away from the nozzle so as to have a thickness of 25 mm. Next, pretreatment was performed at a relative humidity of 80% RH and a temperature of 80 ° C. for 6 hours.
After this pretreatment, the mixture was fired at a temperature of 900 ° C. for 2 hours to obtain a three-dimensional network metal oxide.

The porosity of the obtained three-dimensional network metal oxide was 87%. When observed with an electron microscope, FIG.
Was a three-dimensional network metal oxide as shown in FIG. The average diameter of the pillar part is 5 μm, and the average of the length of the pillar is 0.
5 mm.

50 g of this sample was immersed in an aqueous solution of palladium chloride for 2 hours, and palladium was supported by the impregnation method. At this time, the supported amount of palladium was 0.5 wt%. The obtained palladium-supported three-dimensional network metal oxide was used as a catalyst for a methane oxidation reaction. This sample 5
0 g was charged into the catalyst tank, and 1% by volume of methane / air was flowed as a reaction gas while changing the flow rate. The reaction temperature is 350 ° C. FIG. 2 shows the relationship between the space velocity and the conversion rate of methane to carbon dioxide at this time. FIG. 2 shows that the high conversion rate is maintained up to a large space velocity.

[0049]

Example 2 Basic aluminum chloride salt (Al 12w
0.6 g of palladium chloride was added thereto while stirring 300 g of t% Al ₂ (OH) ₅ Cl · nH ₂ O) at room temperature.
To dissolve, and then concentrated at 60 ° C. to prepare a sol. To this sol, 30% by weight of carbon dioxide was added as a pressure increasing agent. Thereafter, when the temperature reached 35 ° C. and the pressure reached 100 kg / cm ² , the orifice diameter was 0.7.
The sol was discharged from a 5φ nozzle. At a position 50 mm away from the nozzle, a plate was deposited to a thickness of 25 mm. This is heated at 120 ° C for 24
Dried for hours. After this pretreatment, the mixture was fired at a temperature of 700 ° C. for 2 hours to obtain a three-dimensional network metal oxide. The porosity of this three-dimensional network metal oxide was 87%. When observed with an electron microscope, the same structure as in FIG. 1 was confirmed, and the average diameter of the portion corresponding to the column was 6 μm.

The obtained three-dimensional network structure was used as a catalyst for a methane oxidation reaction. 50 g of this sample was placed in a catalyst tank, and 1% by volume of methane / air was flowed as a reaction gas while changing the flow rate. The reaction temperature is 350 ° C. Figure 3 shows the relationship between the space velocity and the conversion rate of methane to carbon dioxide.
Shown in It can be seen that a high conversion is maintained up to a large space velocity.

[0051]

Comparative Example 1 A commercially available high specific surface area alumina honeycomb (50
g: 25 mm x 25 mm, length 50 mm, space ratio 50%
Palladium was supported on Iwao Porcelain Industrial Co., Ltd. so as to be 0.5 wt% by the same impregnation method as in the example. This was subjected to the same reaction as in the examples, and the conversion rate of methane to carbon dioxide was evaluated. The result is shown in FIG. Example 1,
At higher space velocities as compared to 2, the conversion is reduced.

[0052]

According to the present invention, it is possible to process a substance to be reacted at a large space velocity with a low pressure loss, to have a large specific surface area, and to have a high activity up to a large reaction gas processing rate. become. Further, according to the method of the present invention, such a three-dimensional network metal oxide can be produced very easily.

[Brief description of the drawings]

FIG. 1 is a simulated view of a sample prepared in Example 1 observed with an electron microscope.

FIG. 2 shows a sample prepared in Example 1 and methane at 1% by volume.
FIG. 3 is a diagram showing the space velocity (SV) of a contained reaction gas and the conversion rate from methane to carbon dioxide.

FIG. 3 shows a sample prepared in Example 2 and 1% by volume of methane.
FIG. 3 is a diagram showing the space velocity (SV) of a contained reaction gas and the conversion rate from methane to carbon dioxide.

FIG. 4 shows a sample prepared in Comparative Example 1 and methane at 1% by volume.
FIG. 3 is a diagram showing the space velocity (SV) of a contained reaction gas and the conversion rate from methane to carbon dioxide.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nibun Tanaka 23 Uji Kozakura, Uji-city, Kyoto Prefecture Unitika's Central Research Laboratory

Claims (5)

[Claims] 1. A three-dimensional network metal oxide comprising at least one type of metal oxide and formed in a three-dimensional network. 2. The method according to claim 1, wherein the diameter of the pillar is 1 μm to 100 μm, the length of the pillar is 1 to 1000 times the diameter, and the total porosity is 10% to 98%. Item 7. The metal oxide according to Item 1. 3. The metal oxide according to claim 1, wherein the metal oxide is a porous material having a specific surface area of 10 m ² / g to 500 m ² / g. 4. The metal oxide according to claim 1, wherein at least one kind of metal exhibiting catalytic activity is supported. 5. A sol containing a metal which is a raw material of a metal oxide material is prepared, and the sol is placed in a container under a high pressure, and the hole is provided with a pressure drop chamber under autogenous pressure or under pressure. 5. The production of a metal oxide according to any one of claims 1 to 4, further comprising the steps of: evaporating the solvent to form the metal oxide in a three-dimensional network form; Method.