JP3285715B2 - Method for producing porous body using metal oxide sol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a carrier for a functional material such as a catalyst or an enzyme, a membrane for filtration and separation of a gas or a liquid, or an electrolytic partition, an absorbent / adsorbent, a desiccant, a filler for gel chromatography, etc. The present invention relates to a method for producing a porous body made of a metal oxide having fine pores.

[0002]

2. Description of the Related Art Conventionally, it has been used as a carrier for various functional materials such as catalysts and enzymes, as a thin film for separating gases and liquids by filtration, as well as as an electrolytic partition, an absorbing and adsorbing agent, a drying agent, and a packing material for gel chromatography. For these, porous bodies made of various materials including organic materials have been used.

[0003] However, as the requirements for impact resistance, abrasion resistance, chemical resistance, heat resistance, and the like for the porous body have been gradually increased, metals having excellent mechanical, thermal, and chemical stability have been developed. Attention has been paid to inorganic porous bodies made of oxides and the like, and various studies have been made.

[0004] As a result, various performances obtained by the conventional porous body are different from those of the inorganic porous body in that the pore size and the pore size distribution of the inorganic porous body applied to the respective applications are different. It has become clear that it is significantly affected by

Therefore, as a method for obtaining a porous body composed of a metal oxide having a fine pore diameter and a fine pore diameter distribution satisfying the above various properties, the metal oxide material is obtained by a sol-gel method using a metal alkoxide as a raw material. Various studies have been made.

However, in the sol-gel method, generally, except for a part such as silicon alkoxide, the metal alkoxide used is very easily hydrolyzed and cannot be uniformly contacted with water when added to water. Nucleation is not uniform, and it is difficult for the size of the sol particles to be uniform, and as a result, there is a disadvantage that the pore size distribution of the obtained porous body made of a metal oxide is widened.

For example, a porous body made of alumina (Al ₂ O ₃ ) is made of an aluminum (Al) alkoxide of 80%.
It is known that γ-Al ₂ O ₃ having an average pore diameter of 10 nm or less can be obtained by hydrolyzing with a large amount of water heated to at least 0 ° C., peptizing with an acid, and calcining. Since the pore size distribution was wide, the required performance was not satisfied, and application to the above-mentioned various uses was impossible.

That is, when performing gas separation using a porous body having fine pores, the characteristics required of the porous body as a separation membrane include a separation coefficient indicating a ratio of separating a target gas from a mixed gas and a separation coefficient. The permeation flow rate of the gas is important.

Generally, gas molecules permeate through pores having a size smaller than the mean free path by Knudsen diffusion, and the permeation flow rate Q at that time is given by the following equation when converted to a standard state.

[0010]

(Equation 1)

In the above equation, M is the molecular weight of the permeating molecule, R is the gas constant, T is the absolute temperature, r is the pore radius, L is the thickness of the separation membrane, and ΔP is the pressure difference between upstream and downstream of the separation membrane. is there.

From this relation, the pore radius r is, for example, 1 /
It can be seen that, when it is reduced to 2, the permeation flow rate Q drops to 1/8.

Therefore, as described above, the fact that the pore size distribution is wide means that the maximum pore size must be equal to or less than the diameter of the target separated product, and the average pore size must be naturally smaller than that of the target separated product. Since it must be much smaller than the diameter, the permeation flow rate will be small, the efficiency will be poor, and it will not be practical.

Therefore, as a method for controlling the pore size and the pore size distribution, aluminum alkoxide is
After hydrolyzing with water at a temperature of not more than 80 ° C., by heating to not less than 80 ° C. and pulverizing and firing, a porous body composed of γ-Al ₂ O ₃ having an average pore diameter of 22 ° and a relatively narrow pore diameter distribution is obtained. The method of production and after adding β-diketone to an alcohol solution of aluminum alkoxide, hydrolyzing to obtain a bulk gel body, followed by drying and firing, to form an alumina porous body having a pore diameter of 10 to 500 ° A production method and the like have been proposed (see JP-A-5-238845 and JP-A-2-196076).

[0015]

However, the above γ
In the method for producing a porous body composed of Al ₂ O ₃ , an aluminum alkoxide is hydrolyzed with water at a temperature of 80 ° C. or lower and then heated to a temperature of 80 ° C. or higher to peptize. Lights and the like are generated, and a means such as a centrifugal separation method has to be employed to remove the via lights and the like, which causes a problem that the operation procedure becomes complicated.

Further, in the production method in which a bulk gel body formed by adding only β-diketone to an aluminum alkoxide to obtain an alumina porous body has a wide pore diameter distribution, the above-mentioned performance requirements for various applications are not satisfied. There was a problem that.

[0017]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a simple operation using a metal oxide sol prepared so that the pore size and the pore size distribution can be controlled. It is an object of the present invention to provide a production method by which a porous body having a narrow pore size distribution and excellent in a separation coefficient and a permeation flow rate can be efficiently obtained.

[0018]

Means for Solving the Problems The present inventors have made intensive studies on the above-mentioned problems and found that Al, Ti and Sn
For any one of the metal alkoxides, a solution obtained by adding a water-soluble organic solvent and a compound that reduces the reactivity of the alkoxide to water is added to water and hydrolyzed, or When aggregates or precipitates are formed, subsequently, an inorganic acid or an organic acid is added to the solution to peptize, or a water-soluble organic solvent and a water-soluble alkoxide for the metal alkoxide are used. A metal oxide sol prepared by any method of adding a solution to which a compound that reduces reactivity is added to water to which acid is added and hydrolyzing the solution is subjected to atmospheric pressure at a temperature exceeding room temperature and 60 ° C. or less. After drying under an oxidizing atmosphere,
It has been found that sintering at a temperature of 1000 ° C. for 0.1 to 10 hours can provide a porous metal oxide sintered body having a small pore size distribution.

[0019]

According to the method of the present invention for producing a porous body using a metal oxide sol, during the preparation of the metal oxide sol, the metal alkoxide is first diluted with an organic solvent. When added to water, it is efficiently dispersed to generate fine metal oxide sol nuclei.

In addition, by adding a compound that reduces the reactivity of the metal alkoxide to water to the metal alkoxide and the organic solvent, when the metal alkoxide is hydrolyzed, the first formed amorphous hydroxide becomes a metal oxide. The metal alkoxide, which is highly reactive, undergoes hydrolysis before being sufficiently dispersed in water to form a core of a metal oxide sol having a large particle diameter until it is transformed into particles. To prevent accidents.

Furthermore, the size of the once formed metal oxide primary particles does not change during the subsequent peptization process, and the conditions during hydrolysis of the metal alkoxide are determined by drying and firing the obtained metal oxide sol. This determines the pore size and pore size distribution of the porous body obtained in this manner.

Therefore, according to the present invention, a metal oxide sol in which particles are uniformly dispersed can be prepared, and when a porous body is produced using the metal oxide sol, fine crystal particles are uniformly arranged. A porous body having a narrow pore distribution is obtained.

[0023]

EXAMPLES Hereinafter, a method for producing a porous body using the metal oxide sol of the present invention will be described in detail.

The present invention is directed to any of Al, Ti and Sn.
Against Kano metal alkoxide, solution the addition of a compound that reduces the reactivity to water soluble organic solvent and the alkoxide in water, coagulated not temperature or higher, was added to a temperature below the water does not boil hydrolyze Or if the hydrolysis causes aggregates or precipitates,
Subsequently, an inorganic acid or an organic acid is added to the solution to deflocculate or, for a metal alkoxide, a solution obtained by adding a water-soluble organic solvent and a compound that reduces the reactivity of the alkoxide to water, The metal oxide sol prepared by any of the above-mentioned methods of adding the acid to the same water as described above and hydrolyzing it is subjected to an atmosphere at a temperature exceeding room temperature and 60 ° C. or less.
After drying medium, 400 to 1000 ° C. in an oxidizing atmosphere
At a temperature of 0.1 to 10 hours to obtain a porous body.

In the present invention, the metal alkoxide used as a starting material includes aluminum (Al),
Examples include ethoxide, isopropoxide, butoxide, and 2-butoxide of any one of titanium (Ti) and tin (Sn). Among them, alkoxides of aluminum (Al) and titanium (Ti) are preferable.

Examples of the organic solvent which is uniformly mixed and soluble in water include alcohols such as ethanol, 2-propanol, 2-butanol, 2-methoxyethanol and 2-ethoxyethanol.

Compounds that reduce the reactivity of the alkoxide with water include carboxylic anhydrides such as acetic anhydride and maleic anhydride; acetoacetate esters such as methyl acetoacetate, ethyl acetoacetate and propyl acetoacetate; Dicarboxylic acid esters such as dimethyl acid, diethyl malonate and dipropyl malonate, β-diketones such as acetylacetone, and N, N ′ dimethylmonoethanolamine, N, N ′ diethylmonoethanolamine;
Examples thereof include ethanolamines such as monoethanolamine, diethanolamine, and triethanolamine.

However, it is more effective to use the above compounds in the preparation of metal oxide sols as shown below, due to the difference in their chemical properties.

That is, when any one of a carboxylic anhydride, an acetoacetic ester and a dicarboxylic ester is used as the compound, for example, in the case of an aluminum alkoxide, one compound is added to the aluminum alkoxide.
After adding at a rate of 0 to 100 mol% and sufficiently stirring, the solution is added to water and stirred to hydrolyze.

At this time, in order to efficiently disperse the metal alkoxide as a raw material in water and generate fine nuclei of the metal oxide sol, it is desirable to add the solution with vigorous stirring.

In particular, with respect to aluminum alkoxide, if the temperature at which the solution is added to water is lower than 80 ° C., an amorphous hydrate is formed, and thereafter, it changes into a non-peptizable bayerite or the like. The temperature of the water is preferably 80 ° C. or higher.

In the case of other alkoxides such as titanium alkoxide , the temperature of water is not particularly limited, and may be any temperature as long as it is higher than a temperature at which it does not coagulate and lower than a temperature at which it does not boil.

When a β-diketone such as acetylacetone is used as the compound, since the β-diketone does not itself generate an acid, an inorganic acid or an organic acid is added to the dispersion to peptize for a certain period of time. It is necessary to
You.

In particular, with respect to the aluminum alkoxide, β-diketone is added in the same manner as in the above method, and the solution is added and hydrolyzed while vigorously stirring water at 80 ° C. or higher. After adding an inorganic acid such as nitric acid and perchloric acid, or an organic acid such as acetic acid, trichloroacetic acid and oxalic acid, the temperature is 80 ° C. or more, particularly 80 to 95 ° C.
The peptization may be performed while stirring at a temperature of about 0.5 to 72 hours.

At this time, the addition amount of the inorganic acid or the organic acid is 3 to 10 mol based on the aluminum alkoxide.
% Is appropriate. The same applies to other alkoxides such as titanium alkoxide , and the amount of the acid added is
It is at least 3 mol%, preferably 3 to 10 mol%, based on each metal alkoxide.

[0036] Incidentally, as the compound, a carboxylic acid anhydride, acetoacetic ester, in the case of using any of the dicarboxylic acid ester, because these compounds themselves in water to produce a hydrolyzed organic acids, especially not necessarily Add acid
However, the acid may be newly added for peptizing aggregates of metal oxide sol particles.

When an organic base such as ethanolamine is used as the compound, a neutralization reaction occurs even if an inorganic acid or an organic acid is directly added to the solution after the hydrolysis to effectively peptize. Since it is not possible, it is more effective to once filter the formed precipitate, remove the organic base by washing, disperse the precipitate in pure water again, and add an inorganic or organic acid to peptize.

The metal oxide sol thus obtained is
Fine metal oxide or hydroxide sol particles are uniformly dispersed to form a sol solution containing substantially no aggregate.

The metal oxide sol thus obtained is dried under atmospheric pressure in a temperature range from room temperature to 60 ° C.
The dried product is dried in air at a temperature of 400 to 1000 ° C. for 0.1 hour.
By firing for about 1 to 10 hours, a porous powder can be obtained.

In order to obtain a bulk porous body, the dried metal oxide is formed into a desired shape by a desired forming means, for example, a method such as a die press, a cold isostatic press, or an extrusion. After molding, firing may be performed under the above conditions.

When a sheet-like or film-like porous body is obtained, the metal oxide sol is used as it is, or a thickener such as polyethylene glycol is added, and the resulting mixture is subjected to a doctor blade method or a dip coating method. The method can be applied to the surface of an arbitrary substrate by the method described above, dried, and then fired under the same firing conditions as described above.

The drying conditions are limited to a temperature range from room temperature to 60 ° C. or lower in order to obtain quick drying efficiency and to prevent agglomeration at high temperatures.

Further, the firing temperature is set at 400 to 1000 ° C.
The reason for limiting the temperature range is that if the temperature is lower than 400 ° C., an organic substance remains, deteriorating the properties as a separation membrane, and poor adhesion of the separation membrane to a support is likely to occur.
If the temperature exceeds 0 ° C., the grain growth proceeds, and the specific surface area sharply decreases.

Further, if the firing time at the firing temperature is less than 0.1 hour, organic substances may remain,
Conversely, if it exceeds 10 hours, the grain growth proceeds, and for the same reason as the firing temperature, it is limited to about 0.1 to 10 hours.

The metal oxide porous body thus obtained has fine pores of nm (nanometer) class formed uniformly, and the distribution of the pore diameter is also apparent from Examples described later. Thus, it has a very narrow distribution.

Example 1 In a well-dried glove box, 0.1 mol of aluminum trisec-butoxide (Al (O-sec-B) was placed in a 100 ml flask.
u) ₃ ), and add 0.3 as a water-soluble organic solvent
mol of 2-methoxyethanol (MeO-CH ₂ -C
H ₂ -OH) and 0.01 mol of acetylacetone ((CH ₃ CO) ₂ CH ₂ ) as the above-mentioned compound were added and mixed well, then taken out of the glove box and vigorously poured into 180 ml (10 mol) of water heated to 85 ° C. It was added with stirring.

Thereafter, after stirring for 30 minutes, 0.007 mol of nitric acid was added to the reaction solution, and the solution was heated to 95 ° C. and refluxed for further 16 hours to prepare an almost colorless and transparent boehmite (AlOOH) sol.

The boehmite thus obtained (AlOO)
H) drying the sol at 60 ° C. for 3 days,
Thereafter, the powder was fired at 500 ° C. for 1 hour in the air to obtain a porous powder having a BET specific surface area of 333 m ² / g and an average pore diameter of 33 °.

Using the porous powder, the pore size distribution was measured by a nitrogen adsorption measuring apparatus, and the results shown in FIG. 1 were obtained. As is apparent from FIG. 1, the porous body obtained by the production method according to the present invention has a very narrow pore size distribution even in comparison with Comparative Example 1 described later.

Example 2 An aluminum alkoxide solution prepared in the same manner as in Example 1
ol of nitric acid at 85 ° C. and 180 ml of water (10 mol
1) was added with vigorous stirring.

After that, the same processing as in the first embodiment is performed and the BET
A porous powder having a specific surface area of 326 m ² / g and an average pore diameter of 35 ° was obtained.

FIG. 2 shows the pore size distribution measured in the same manner as in Example 1.

Example 3 In a sufficiently dried glove box, 0.1 mol of aluminum trisec-butoxide (Al (O-sec-B) was placed in a 100 ml flask.
u) ₃ ), and add 0.3 as a water-soluble organic solvent
mol of 2-methoxyethanol (MeO-CH ₂ -C
H ₂ —OH) and acetic anhydride ((CH ₃ C
O) ₂ CO) and sufficiently mixed, taken out of the glove box, and heated to 85 ° C. in 180 ml of water (10 ml).
mol)) with vigorous stirring.

Thereafter, after stirring for 30 minutes, 0.007 mol of nitric acid was added to the reaction solution, and the solution was heated to 95 ° C. and refluxed for further 16 hours to obtain milky boehmite (Al
OOH) sol was obtained.

The boehmite thus obtained (AlOO)
H) The sol is sufficiently dried at a temperature of 60 ° C. for 3 days, and calcined in the air at a temperature of 500 ° C. for 1 hour to obtain a porous powder having a BET specific surface area of 330 m ² / g and an average pore diameter of 33 °. Was.

On the other hand, the pore size distribution measured in the same manner as in Example 1 is shown in FIG.

Example 4 To a reaction solution prepared in the same manner as in Example 3, 0.007 mol of nitric acid was added, and the solution was heated to 95 ° C., refluxed for 0.5 hour, and returned to a colorless and transparent boehmite (AlOOH). ) A sol was obtained.

The boehmite (AlOOH) sol was dried and calcined in the same manner as in Example 3 to obtain a BET specific surface area of 344.
A porous powder having m ² / g and an average pore diameter of 32 ° was obtained.

FIG. 4 shows the pore size distribution of the porous powder measured in the same manner as in Example 1.

Example 5 In Example 4, the reaction solution was refluxed for 0.5 hour at a temperature of 95 ° C. without adding nitric acid to obtain a colorless and transparent boehmite (AlOOH) sol.

The boehmite (AlOOH) sol was dried and fired in the same manner as in Example 3 to obtain a BET specific surface area of 345.
A porous powder having m ² / g and an average pore diameter of 32 ° was obtained.

FIG. 5 shows the pore size distribution of the porous powder obtained in the same manner as in Example 1.

(Example 6) In a well-dried glove box, 0.1 mol of tetra-n-butoxytitanium (Ti (On-Bu) ₄ ) was placed in a 100-ml flask, and a water-soluble organic solvent was added thereto. 0.3 mol of 2-methoxyethanol (MeO—CH ₂ —CH ₂ —OH) and 0.05 mol of acetic anhydride (CH ₃ C
O) ₂ CO) was added and mixed well, taken out of the glove box, and heated to 85 ° C. in 180 ml of water (1
0 mol) with vigorous stirring.

Thereafter, the solution was heated to 95 ° C. and refluxed for another 2 hours to obtain an almost transparent titania sol. This sol is sufficiently dried at a temperature of 60 ° C. for 3 days, and then calcined in the air at 500 ° C. for 1 hour to have a BET specific surface area of 138.
A porous powder having m ² / g and an average pore diameter of 49 ° was obtained.

FIG. 6 shows the pore size distribution measured in the same manner as in Example 1. The pore size distribution of Comparative Example 2 described later is also shown.

(Example 7) In Example 6, the alkoxide solution mixed in the glove box was mixed with water 18 at room temperature.
It was added to 0 ml (10 mol) with vigorous stirring, and stirring was continued for 2 days to obtain an almost colorless and transparent titania sol. This sol was sufficiently dried at a temperature of 60 ° C. for 3 days, and calcined in the air at 500 ° C. for 1 hour to obtain a porous powder having a BET specific surface area of 116 m ² / g and an average pore diameter of 52 °.

FIG. 7 shows the pore size distribution of the porous body measured in the same manner as in Example 1.

Example 8 In a well-dried glove box, 0.1 mol of tetra-n-butoxytin (Sn (On-Bu) ₄ ) was placed in a 100 ml flask, and this was used as a water-soluble organic solvent. 0.3mol of 2-methoxyethanol _{(MeO-CH 2 -CH 2 -OH} ) and 0.05mol acetic anhydride as described above for compound ((CH
₂ CO) ₂ CO) was added and mixed well, then taken out of the glove box, and 180 ml of water heated to 85 ° C.
(10 mol) with vigorous stirring.

Thereafter, the solution was heated to 95 ° C. and refluxed for another 2 hours to obtain a precursor sol of tin oxide.

Next, this sol is sufficiently dried at a temperature of 60 ° C. for 3 days, and calcined in the air at a temperature of 500 ° C. for 1 hour to obtain a porous material having a BET specific surface area of 112 m ² / g and an average pore diameter of 56 °. Quality powder was obtained.

FIG. 8 shows the pore size distribution measured in the same manner as in Example 1. The pore size distribution of Comparative Example 3 described later is also shown.

Comparative Example 1 0.1 mol of aluminum trisec-butoxide (Al (O-sec-B
Water 180 ml (10Mo heating the u) ₃₎ in 85 ° C.
The mixture was added to 1) with vigorous stirring. After 30 minutes, 0.007 mol of nitric acid was added to the reaction solution, and the solution was heated to 95 ° C and refluxed for 16 hours to obtain a milky white sol solution.

Next, this sol solution was heated at 60 ° C. for 3 hours.
Days, and calcined in air at 500 ° C. for 1 hour to have a BET specific surface area of 254 m ² / g and an average pore diameter of 49.
多孔 of a porous powder was obtained.

FIG. 1 shows the pore size distribution of the porous powder.
Are shown together. As is apparent from FIG. 1, the pore size distribution is wider than those of Examples 1 to 5 which are the production methods of the present invention, and the average pore diameter of the present invention is 32 to 3 as described above.
5% in this comparative example,
It has become large.

COMPARATIVE EXAMPLE 2 0.1 mol of tetra n-butoxytitanium (Ti (On-Bu) ₄ ) was heated to 85 ° C.
Was added to 180 ml (10 mol) of heated water with vigorous stirring. After 30 minutes, 0.007 mol was added to the reaction solution.
The solution was heated to 95 ° C. and refluxed for another 16 hours to obtain a milky white sol solution.

Next, the sol solution was heated at 60 ° C. for 3 hours.
Days, and calcined at 500 ° C. for 1 hour in the air to have a BET specific surface area of 89 m ² / g and an average pore diameter of 67 ° C.
Was obtained.

The pore size distribution of this comparative example was measured in the same manner as in Example 1, and the results are also shown in FIG.

As is clear from FIG. 6, the pore diameter distribution is wider than that of Examples 6 and 7 based on the production method of the present invention, and the average pore diameter is 49 to 52 ° in the present invention. This comparative example is as large as 67 °.

Comparative Example 3 0.1 mol of tetra-n-butoxytin (Sn (On-Bu) ₄ ) was added to 180 ml (10 mol) of water heated to 85 ° C. with vigorous stirring. 0.007 mol of nitric acid was added to the reaction solution, and the solution was heated to 95 ° C. and refluxed for 2 hours to obtain a sol solution.

Next, this solution was sufficiently dried at a temperature of 60 ° C. for 3 days, fired in the air for 1 hour, fired at 500 ° C. for 1 hour, and had a BET specific surface area of 98 m ² / g and an average pore diameter of A 62 ° porous powder was obtained.

The pore size distribution of this comparative example was measured in the same manner as in Example 1, and the results are also shown in FIG.

As is apparent from FIG. 8, the pore size distribution is wider than that of Example 8 which describes the production method of the present invention, and the average pore diameter is 56 ° in the present invention. In the example, it is as large as 62 °.

[0083]

As described above, according to the method for producing a porous body using the metal oxide sol of the present invention, the pore size,
With a simple operation procedure using a metal oxide sol prepared so that the pore size distribution can be controlled, until the amorphous hydroxide first generated during hydrolysis changes to metal oxide particles, Since the particles are efficiently dispersed uniformly and the nuclei of the fine metal oxide sol can be generated, the size of the once formed metal oxide primary particles does not change during the subsequent peptization process, so it is narrow. High-precision filtration / separation membranes with a pore size distribution and excellent filtration coefficient and permeation flow rate, which can be applied to carriers of functional materials such as catalysts and enzymes, gases and liquids, viruses, etc. A porous body that satisfies the required performance of various uses such as an adsorbent, a desiccant, and a filler for gel chromatography can be efficiently obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a pore size distribution of a porous body using a boehmite sol according to a production method of the present invention and a porous body of a comparative example.

FIG. 2 is a view showing a pore size distribution of a porous body using a boehmite sol according to another production method of the present invention.

FIG. 3 is a view showing a pore size distribution of a porous body using a boehmite sol according to another production method of the present invention.

FIG. 4 is a diagram showing a pore size distribution of a porous body using a boehmite sol according to another production method of the present invention.

FIG. 5 is a diagram showing a pore size distribution of a porous body using a boehmite sol according to another production method of the present invention.

FIG. 6 is a view showing a pore size distribution of a porous body using a titania sol according to the production method of the present invention and a porous body of a comparative example.

FIG. 7 is a view showing a pore size distribution of a porous body using titania sol according to another production method of the present invention.

FIG. 8 is a diagram showing pore size distributions of a porous body using a tin oxide precursor sol according to the production method of the present invention and a porous body of a comparative example.

Claims (3)

(57) [Claims] 1. A metal alkoxide of any of Al, Ti and Sn is added to a water-soluble organic solvent and a carboxylic acid anhydride.
A metal oxide sol prepared by adding a solution containing any one of a substance, an acetoacetate ester and a dicarboxylic acid ester to water and hydrolyzing the resultant is dried at atmospheric pressure at a temperature exceeding room temperature and 60 ° C. or lower. 400 to 1 in an oxidizing atmosphere
A method for producing a porous body using a metal oxide sol, characterized by firing at a temperature of 000 ° C. 2. A metal alkoxide of any of Al, Ti and Sn is added to a water-soluble organic solvent, β-diketone and
A metal oxide sol prepared by adding a solution containing any one of ethanolamine to water, hydrolyzing the mixture, adding an inorganic acid or an organic acid, and deflocculating the solution is heated at a temperature exceeding room temperature to 60 ° C. or less. After drying under atmospheric pressure , 4
A method for producing a porous body using a metal oxide sol, characterized by firing at a temperature of 00 to 1000 ° C. 3. A metal alkoxide selected from the group consisting of Al, Ti and Sn , a water-soluble organic solvent, β-diketone and
Solution the addition of any one of ethanolamine, a metal oxide sol prepared by hydrolyzing added to the water plus the inorganic or organic acid, at a temperature of 60 ° C. over the room temperature atmospheric
After drying under atmospheric pressure , 400 to 100 in an oxidizing atmosphere
A method for producing a porous body using a metal oxide sol, characterized by firing at a temperature of 0 ° C.