JPH02145489A - Inorganic porous material - Google Patents

Abstract

PURPOSE:To obtain an inorganic porous material having large pore volume and gap and utilizable as heat-insulation material, adsorbent, etc., by mixing a dilatable inorganic laminar compound in dilated state with a colloidal inorganic compound and drying the mixture in supercritical state. CONSTITUTION:The objective inorganic porous material is produced by adding ethanol, methanol, CO2, dichlorodifluoromethane, ethylene, etc., to a mixture of a dilatable inorganic laminar compound (e.g., Na-montmorillonite, Ca- montmorillonite, synthetic hectorite, synthetic smectite, acid clay or synthetic mica) of dilated state and a colloidal inorganic compound (e.g., TiO2, Al2O3, ZrO2 or Fe2O3) and drying the obtained mixture in supercritical state.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an inorganic porous body.

[Conventional technology]

Conventionally, inorganic porous bodies made by drying a swellable inorganic layered compound by hot air drying or freeze drying have been known (Japanese Patent Publication No. 62-20130, Japanese Patent Application Laid-Open No. 60-137).
Publication No. 813). These inorganic porous bodies are dried using pillar materials inserted between the eyebrows of an inorganic layered compound as supports so as to maintain a gap between the eyebrows. These inorganic porous bodies can be used as functional materials such as heat insulating materials and adsorbents [Problem to be solved by the invention] However, the above-mentioned inorganic porous bodies have a pore volume of 0.8
It is low at less than cc/g, the distance between the eyebrows is not wide enough to satisfy, and its insulation and adsorption properties are insufficient, making it difficult to call it a highly functional material.

Therefore, an object of the present invention is to provide an inorganic porous body having a large pore volume and large voids that act effectively.

[Means to solve the problem]

In order to solve the above problems, the inorganic porous body according to each of the inventions of claims 1 to 5 is obtained by drying a mixture of a swellable inorganic layered compound and a colloidal inorganic compound in a swollen state in a supercritical state. It is said that

The inorganic porous body according to each of claims 2 to 5 further comprises:
It is provided that the mixture also contains an organic pillar material.

The inorganic porous body according to each of claims 3 to 5 further comprises:
Colloidal inorganic compounds include T i Ox , Ait O
s, zro! and at least one selected from the group consisting of Fe, O, and Fe.

The inorganic porous body according to each invention of claim 4.5 further comprises:
The swelling inorganic layered compound is Na-montmorillonite, C
It is said to be at least one selected from the group consisting of a-montmorillonite, synthetic hectorite, synthetic smectite, acid clay, and synthetic mica.

In the inorganic porous body according to the invention of claim 5, the swellable inorganic layered compound in a swollen state further comprises at least one fluid selected from the group consisting of ethanol, methanol, carbon dioxide, dichlorodifluoromethane, and ethylene. It is said to contain.

[For production]

By drying the inorganic layered compound in a swollen state in a supercritical state, condensation of the solvent (fluid) is suppressed, and the layered compound particles are dried in a manner that maintains the aggregation state in the solvent. An aggregate with large voids between particles of the inorganic layered compound is obtained. Moreover, by mixing a colloidal inorganic compound, the aggregated state becomes stronger, and a porous body with a larger amount of voids can be obtained. In addition, this colloidal inorganic compound causes an insertion reaction in a part of the glabella, and serves as a support for the glabella of the inorganic layered compound to maintain the glabellar distance. Therefore, it is highly porous,
It forms an aggregate with a large pore volume, resulting in an inorganic porous material with excellent adsorption and heat insulation properties.

The organic pillar material also acts as a support between the eyebrows of the inorganic layered compound. However, depending on usage conditions, residual organic pillar material, particularly residual carbon, may pose a problem. When an inorganic porous material is fired to remove the organic pillar material, the number of steps increases and carbon inevitably remains.On the other hand, if drying is performed in a supercritical state, the organic pillar material becomes Because it is extracted by a fluid in a critical state,
During drying, it can be removed from the glabella along with the same fluid.Drying in a supercritical state is very convenient because the above-mentioned firing step is not required and residual carbon can be suppressed.

As colloidal inorganic compounds, T iOt , A 1t
When at least one selected from the group consisting of Os 2 , ZrOx and Fetus is used, these compounds have a catalytic function, so that an inorganic porous body having a catalytic function is formed.

The swelling inorganic layered compound is Na-montmorillonite, C
a- At least one selected from the group consisting of montmorillonite, synthetic hectorite, synthetic smectite, acid clay, and synthetic mica, the porosity of the inorganic porous body,
It is convenient for functionality.

When the fluid containing the swellable inorganic layered compound in a swollen state is at least one selected from the group consisting of ethanol, methanol, carbon dioxide, dichlorodifluoromethane, and ethylene, when the fluid is water; Drying in a supercritical state can be easily carried out compared to drying in a supercritical state. This is because these fluids have significantly lower critical pressures and critical temperatures than water. Of course, if the water contained in the swellable inorganic layered compound in a swollen state is replaced with another fluid, such as ethanol, and this replaced fluid is further replaced with another fluid, such as carbon dioxide.
Even when using a component-based fluid and drying in a supercritical state,
Since the critical temperature and pressure conditions are gentler than that of water, drying is easy.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings showing one embodiment thereof.

FIG. 1 is a schematic diagram showing an enlarged inorganic porous body according to the invention according to claim 1. This inorganic porous body 10 is a porous body formed by drying a mixture of swelling inorganic layered compounds 1 and colloidal inorganic compounds 4 in a swollen state in a supercritical state. The inorganic porous body 10 is a card house-like or sponge-like aggregate in which petal-like or semi-shaped inorganic layered compounds 1 are assembled. Therefore, large voids are formed between the swellable inorganic layered compounds, resulting in a highly porous body with a large pore volume. The inorganic porous body 10 having such a structure can be made by drying a mixture of a colloidal inorganic compound and a swellable inorganic layered compound in a supercritical state, but it can also be made by other methods.

As shown in FIG. 2, each inorganic layered compound 1 has a colloidal inorganic compound 4 partially between its layers 11 and 11.
... has been inserted (intercalated). The colloidal inorganic compound 4 may act as an inorganic pillar material, thereby forming a layer 11.11 of the inorganic layered compound 1.
The gap 2 between them is made larger.

The inorganic porous body according to the present invention is manufactured, for example, as follows, but the manufacturing method is not limited to the following. First, the swellable inorganic layered compound is swollen. continue,
The swollen swellable inorganic layered compound and the colloidal inorganic compound are mixed. Stirring may be used for mixing. If necessary, an organic pillar material is also mixed. The fluid contained in the mixture is then removed by drying the mixture in a supercritical state.

The solvent used for swelling the swellable inorganic layered compound is not particularly limited; for example, polar solvents such as water, ethanol, methanol, DMF (dimethylformamide), DMSO (dimethyl sulfoxide), and acetone can be used individually. , or two or more kinds are used in combination. Water is generally used as the solvent.

Examples of the swellable inorganic layered compound include Na-montmorillonite, Ca-montmorillonite, synthetic hectorite, and synthetic smectite (for example, 3-octahedral compounds. Examples of 3-octahedral compounds include: phyllosilicate minerals such as synthetic sabonite, Na-hectolite, Li-hectolite, Na-teniolite, Li-teniolite), acid clay, and synthetic mica (here, either natural products or synthetic products may be used) These may be used alone or in combination, but it goes without saying that the invention is not limited to these. In addition, when using a poorly swellable inorganic layered compound such as Ca-montmorillonite and acid clay, it is necessary to apply strong shearing force by crosstalk etc. at the time of swelling. A substance such as a swellable clay mineral (which may be either a natural product or a synthetic product) is a combination of a large number of swellable inorganic layered compounds 1 shown on the left side of FIG. 4. This compound 1, which is the main material, is mixed with a solvent such as water, and further kneaded if necessary, and as shown on the right side of Figure 4, the solvent 3 is impregnated between the layers 11 and 11 to make them swell in advance. I'll keep it. The glabellar spacing of an inorganic layered compound when swollen is, for example, 150 in the case of clay minerals.
The colloidal inorganic compound of human size is not particularly limited, but in consideration of functionality, it is preferable to have a function such as a catalytic function. Such compounds include Ti
Examples include Oz, Zr0t, AJgOs, Few O8, etc., and these may be used alone or in combination. Since these colloidal inorganic compounds are positively charged, they form complexes with negatively charged inorganic layered compounds such as clay minerals, and adhere to the surface of the inorganic layered compounds and between the eyebrows. Then, by drying in a supercritical state, it becomes fine particles. When using silica sol as a colloidal inorganic compound, it may be necessary to chemically modify the surface of the particles with a cationic inorganic compound, alcoholade, etc. It may be necessary to use it.

However, in the case of the colloidal inorganic compounds exemplified above, for example, commercially available sols can be used as they are, and mass production effects can also be obtained.

Regarding the particle size (average particle size) of colloidal inorganic compounds,
In this invention, although not particularly limited, for example, 50 to
The particle size is said to be about 200 people. For example, 'p i O
*Sol has a particle size of about 150, and alumina sol has a particle size of 1.
Approximately 80 to 200 people. The particle size of the colloidal inorganic compound influences whether the colloidal inorganic compound performs the insertion reaction of the inorganic layered compound into the glabella, but in this invention, the insertion reaction of the inorganic layered compound into the glabella is not performed. The particle size may be approximately 100%.

Further, in the present invention, an organic pillar material can be mixed with and inserted into the swellable inorganic layered compound alone or together with a colloidal inorganic compound. The organic pillar material is not particularly limited, but for example, at least one selected from water-soluble polymer compounds, quaternary ammonium salts, higher fatty acids, amphoteric surfactants, and choline compounds is used. When an organic pillar material is mixed with a swellable inorganic layered compound together with a colloidal inorganic compound or inserted between the eyebrows of the swellable inorganic layered compound, the organic pillar material 5 becomes an inorganic porous material, as shown in FIG. 1 layer 1
Colloidal inorganic compounds (existing between the particles of the inorganic layered compound and/or between the eyebrows) 4.4 Prevent the aggregation of the colloidal inorganic compounds, 11. It functions to slow down the movement of the colloidal inorganic compound 4 inserted between the layers 11 and 11, and to keep it between the layers 11 and 11. For this purpose, it is preferable to use a water-soluble polymer compound and/or a quaternary ammonium salt.

The water-soluble polymer compound is not particularly limited, and examples include polyvinyl alcohol, polyethylene glycol (
(polyethylene oxide), methylcellulose, carboxymethylcellulose (CMC), polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinylpyrrolidone, etc., each alone or in combination
Used in combination with more than one species.

There are various possible quaternary ammonium salts and higher fatty acids, among which octadecyl group,
Those having groups such as hexadecyl group, tetradecyl group and dodecyl group are preferred. Such quaternary ammonium salts include octadecyltrimethylammonium salt, diotadecyldimethylammonium salt, hexadecyltrimethylammonium salt, dioctadecyldimethylammonium salt, tetradecyltrimethylammonium salt, diotadecyldimethylammonium salt, and the like. Higher fatty acids include palmitic acid (hexadecyl acid), stearic acid (octadecyl acid), oleic acid (cis-9-octadecenoic acid), linoleic acid (ci
s-9, cis-12-octadecadienoic acid), etc.
Each may be used alone or in combination of two or more.

Various choline compounds can be considered, but for example, (HOCH* CHg N (CHg) x )”0
H− (i.e., Cs H+sNO*), Cs H
t4(INOlC, H,, N0C4H, O,, C, Hth NOCm Ht Ov, Cs HraNOC-HI2
07 is preferred, and each can be used alone or in combination of two or more.

There are various possible amphoteric surfactants, but
Among these, preferred are those in which the cation part is an aliphatic amine type and the anion part has at least one group selected from carboxyl group, sulfate ester group, sulfone group, and phosphate ester group. .

When using an organic pillar material in this invention, materials other than those mentioned above can be used as long as they can be inserted between the eyebrows of the swellable inorganic layered compound.

Next, a more specific explanation will be given. The colloidal inorganic compound is added dropwise to the previously swollen inorganic layered compound and mixed. The temperature during mixing is not particularly limited, but is preferably around 60 to 70°C. A colloidal inorganic compound mixed with an inorganic layered compound is inserted into the glabella of all the inorganic layered compounds, some cases are not inserted into the glabella of all the inorganic layered compounds, and some cases are inserted into the glabella of the inorganic layered compound. There may be a mixture of those that are not. These differences are caused by the gap between the eyebrows when the inorganic layered compound is swollen and the particle size of the colloidal inorganic compound.

After the reaction solution as described above is centrifuged to turn the sample into a gel state, it is oriented into a plate shape using a spatula or the like.

This plate-shaped body is dried in a supercritical state. Of course, drying may be started from the state in which the material is in the reaction solution.

Here, the supercritical state includes not only a state exceeding the critical point but also a state just at the critical point. A method for creating a supercritical state is, for example, to directly heat and pressurize the solvent contained in the swelling layered compound, such as the water contained between the eyebrows, to reach a state above its critical point. However, in such a method, the critical point of water is extremely high, with a critical temperature of 374.2°C and a critical pressure of 217.6 atm, so it is necessary to use an autoclave or the like. In order to avoid this, the water in the swellable layered compound is replaced with ethanol, for example, and then carbon dioxide is added, and while gradually replacing ethanol with carbon dioxide, the two components of carbon dioxide and ethanol are added. The supercritical state may be brought about by heating and pressurizing the system to a temperature and pressure above the critical point.In this case, carbon dioxide at a temperature above the critical point may be fed into the system for substitution.

Drying ends by allowing the fluid in a supercritical state to escape from the system.

By such a method, the agglomeration and condensation during drying can be prevented, the structure before drying can be maintained as it is, and an inorganic porous material with extremely high porosity and a large pore volume can be obtained. An inorganic porous material dried by hot air drying or freeze drying has a significantly smaller pore volume than the inorganic porous material of the present invention. This is because the structure before drying cannot be well maintained.

Note that the fluids that can be used as solvents are not limited to those mentioned above. Things that can be made into a critical fluid within a practical range are:
There are various examples, such as ethanol, methanol, carbon dioxide, dichlorodifluoromethane, and ethylene.

When creating the supercritical state, if the supercritical conditions are selected and drying is performed, organic substances contained in the glabella can be extracted into the supercritical fluid. Therefore, if an organic pillar material is inserted between the eyebrows to expand and hold the layer spacing, only the organic pillar material can be extracted and removed by drying under appropriately selected supercritical conditions. becomes possible. In this way, the organic pillar material can be removed from the dried sample without baking it. The firing step can be omitted, and the problem of carbon remaining between the eyebrows after firing, which limits the use of catalytic effects, etc., can also be solved.

For reference, critical conditions for major fluids are shown in Table 1.

Table 1 Since the inorganic porous material according to the present invention has a large specific surface area, it can be used as having deodorizing action, adsorption action, catalytic action, etc. Furthermore, since the pore volume is large, it can also be used as a heat insulating material. However, the uses of the inorganic porous material of the present invention are not limited to these.

Specific examples and comparative examples of the present invention are shown below, but the present invention is not limited to the following.

Example 1 - Na-montmorillonite, a swellable layered compound swollen with water (Kunipia F manufactured by Kunimine Kogyo Co., Ltd.)
Tie, a colloidal inorganic compound, sol (custom-made product manufactured by Nissan Chemical Industries, Ltd.) was added dropwise to a 0.8 wt% aqueous solution of , mixed, and reacted at 60° C. for 1.5 hours.

After the reaction, washing with ethanol and centrifugation were repeated several times, oriented into a plate shape with a spatula, and heated at 40°C and 80 atm while adding carbon dioxide (Co), which has a relatively low critical point.
After drying for several hours, an inorganic porous material was obtained.

In addition, the mixing ratio of each component is Na-montmorillonite:Ti0t=1:0.6 in weight ratio.

Example 2 An inorganic porous body was obtained in the same manner as in Example 1, except that synthetic smectite (Smecton, manufactured by Kunimine Kogyo Co., Ltd.) was used instead of Na-montmorillonite.

Example 3 An inorganic porous body was obtained in the same manner as in Example 1, except that synthetic mica (sodium tetrasilicon mica manufactured by Topie Industries Co., Ltd.) was used instead of Na-montmorillonite. .

Example 4 In Example 1, Alx was used as a colloidal inorganic compound.
Os sol (Alumina sol-2 manufactured by Nissan Chemical Industries, Ltd.)
An inorganic porous body was obtained in the same manner as in Example 1 except that 00) was used.

Example 5 - Na-montmorillonite, a swellable layered compound swollen with water (Kunipia F manufactured by Kunimine Kogyo Co., Ltd.)
A colloidal inorganic compound, 'l' i 0 t sol (custom made by Nissan Chemical Industries, Ltd.), was added dropwise to a 0.8 wt % aqueous solution of , mixed, and reacted at 60° C. for 1.5 hours.

Next, a quaternary ammonium salt (NOF Corporation Cation AB...octadecyltrimethylammonium chloride) was added to this mixture as an organic pillar material.
The reaction was carried out at 0°C for 1.5 hours.

After the reaction, washing with ethanol and centrifugation are repeated several times, oriented into a plate shape with a spatula, and dried at 40°C and 80 atm for 8 hours while adding carbon dioxide, which has a relatively low critical point, to form an inorganic porous material. I got it.

The mixing ratio of each component is as follows in terms of weight ratio: Na-montmorillonite: 0 g of Ti: quaternary ammonium salt - t:o, s:1.

- Comparative Example An inorganic porous body was obtained in the same manner as in Example 1, except that the drying was carried out with hot air at 60°C.

The specific surface area, pore volume, and deodorizing properties of each of the inorganic porous bodies of Examples 1 to 5 and Comparative Example were investigated, and the results are shown in Table 2. Note that Table 2 also shows the raw materials and drying conditions for the inorganic porous body.

The specific surface area and pore volume are determined by BET in the nitrogen adsorption method.
I investigated using the method.

In order to measure the deodorizing properties, the following two deodorizing experiments were conducted using trimethylamine and methyl mercaptan as odor components.

Experiment ① 0.3 g of the inorganic porous material was placed in a 300 mJ+ Erlenmeyer flask, and the mouth of the Erlenmeyer flask was sealed with a stopper. Next, methyl mercaptan (9
, 16 vol. Samples were taken and measured using a gas chromatograph. As a result of the analysis, if the odor was completely deodorized (gas chromatograph measurement value Oppm), the time until sampling at that time was investigated. When the odor was not completely deodorized, the time required for the gas chromatograph measurements to settle down to a nearly constant value was investigated.

Experiment ■ A porous material was placed in a 30 Qm4 Erlenmeyer flask.
3 g was added and the mouth of the Erlenmeyer flask was sealed with a stopper. Then,
Trimethylamine (9,48
% by volume) was injected, and after 1 minute, the gas in the Erlenmeyer flask was Q, 5 m j! A sample was taken and examined using a gas chromatograph. If the analysis results indicate that the odor has been completely deodorized (gas chromatograph measurement value Oppm), repeat the above operation, and if the odor is not completely deodorized, extend the time before sampling until the odor is completely deodorized. I checked the time.

The main equipment used for measurements etc. is as follows.

Nitrogen adsorption method: Trademark Autosoap 6 manufactured by Quantachrome Co., Ltd. Supercritical drying device: Supercritical outflow device manufactured by Sumitomo Heavy Industries, Ltd. As shown in Table 2, Example 1 and its corresponding comparison When compared with the example, it is clear that the inorganic porous body according to the present invention has a larger specific surface area, pore volume, and void size. Therefore, the inorganic porous body according to the present invention is
Demonstrates excellent deodorizing properties (adsorption or catalytic function). Moreover, when comparing Examples 1 and 5, it can be seen that the effect is further enhanced when an organic pillar material is used.

〔Effect of the invention〕

As described above, the inorganic porous body according to each of the inventions of claims 1 to 5 has well-maintained porosity before drying, has a large specific surface area and pore volume, and has sufficiently large voids. Therefore, in the inorganic porous material according to each of the inventions of claims 2 to 5, which exhibits excellent Il performance, the organic pillar material used serves as a support and the space between the eyebrows of the inorganic layered compound is sufficiently expanded. In addition, colloidal inorganic compounds exist in the doma to prevent agglomeration, and colloidal inorganic compounds inserted between the eyebrows of inorganic layered compounds slow their movement and remain between the layers. For this reason, the inorganic layered compound comes to have sufficient voids between the eyebrows, further increases the pore volume, and increases the porosity. Moreover, the organic pillar material itself can be removed by drying in a supercritical state according to the drying conditions, so there is no need for a firing process to remove the organic pillar material, and no carbon content remains in the inorganic porous body. Therefore, it is highly desirable.

In the inorganic porous body according to each of claims 3 to 5, the colloidal inorganic compound used has functionality, so that the colloidal inorganic compound exists between the particles of the inorganic layered compound and/or between the eyebrows. This gives it added functionality.

The inorganic porous bodies according to the inventions of claims 4 and 5 have good porosity and functionality because the inorganic layered compound used is preferable for use in inorganic porous bodies.

The inorganic porous body according to the invention of claim 5 can be obtained by drying under mild conditions because the fluid contained in the swellable inorganic layered compound in a swollen state can achieve a supercritical state that is gentler than that of water. .

[Brief explanation of the drawing]

FIG. 1 is an enlarged schematic diagram of one embodiment of the inorganic porous body according to the invention of claim 1, FIG. 2 is an enlarged schematic diagram of a part thereof, and FIG.
The figure is an enlarged schematic diagram of a part of one embodiment of the inorganic porous body according to the invention of claim 2, and FIG. 4 is a schematic explanatory diagram showing swelling of the inorganic layered compound.1... Inorganic layered compound 3...
Solvent 4... Colloidal inorganic compound 5... Organic pillar material 10... Inorganic porous body 11... Layer of inorganic layered compound

Claims (1)

[Scope of Claims] 1. An inorganic porous material obtained by drying a mixture of a swellable inorganic layered compound and a colloidal inorganic compound in a swollen state in a supercritical state. 2. The inorganic porous material according to claim 1, wherein the mixture also contains an organic pillar material. 3 The colloidal inorganic compounds are TiO_2, Al_2O
The inorganic porous material according to claim 1 or 2, wherein the porous material is at least one selected from the group consisting of ZrO_2, Fe_2O_3, and Fe_2O_3. 4. Any one of claims 1 to 3, wherein the swelling inorganic layered compound is at least one selected from the group consisting of Na-montmorillonite, Ca-montmorillonite, synthetic hectorite, synthetic smectite, acid clay, and synthetic mica. The inorganic porous body described in . 5. Any one of claims 1 to 4, wherein the swellable inorganic layered compound in a swollen state contains at least one fluid selected from the group consisting of ethanol, methanol, carbon dioxide, dichlorodifluoromethane, and ethylene. The inorganic porous material described.