JPH09295811A - Amorphous porous body and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an amorphous porous body having wide pore diameter distribution and capable of corresponding to various utilizing fields by distributing a micro pore, a meso pore and a macro pore having each prescribed pore size under specific conditions. SOLUTION: A micro pore 23 having 0.35-2nm pore diameter, a meso pore having 2-50nm pore diameter and a macro pore 3 having 50nm to 100μm pore diameter are distributed according to fractal rule. The porous body can be produced as follows by sol gel method. A bicontinuous type microemulsion or liquid crystal, in which (inorganic salt) water forms a continuous phase, comprising a surfactant (A), a cosurfacrant (B), oil, (inorganic salt) water or component A, oil, (inorganic salt) water is used as a template and a metal compound (C) is included in the continuous phase and the component C is subjected to hydrolysis and polycondensation in the continuous phase to produce gel and gel is subjected to deaeration drying and heating. Thereby, oil content, the component A, the component B and the inorganic salt in the template are removed to remove the template and the resultant gel is baked to produce the objective amorphous porous body.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an amorphous porous body having a wide pore size distribution from micropores to mesopores and macropores and a method for producing the same, and more specifically to ordinary uniform pores. Since it has a wider pore size distribution than layered silicates that have the properties of, it has an excellent adsorption carrier and reaction catalyst function, and because it has large macropores, it is excellent in the durability of the function as an adsorption carrier. The present invention relates to an amorphous porous material that can be used as an adsorption carrier or reaction catalyst for a wide range of organic compounds ranging from molecular weight to high molecular weight, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, crystalline porous materials typified by zeolite have been used as catalysts and ion exchangers depending on the physical and chemical characteristics of the pore surface of the porous materials. It is used in a wide range of industrial fields.
However, in the case of such a crystalline porous body, since it has a uniform structure with a pore size of 0.3 to 0.8 nm, it has an excellent function for highly selective catalytic reaction of low molecular weight compounds and the like. However, it has a problem that it cannot be used as a catalyst or an adsorbent for a compound having a bulky molecular structure.

Therefore, in order to control the pore structure of the crystalline porous body, a large number of pillar compounds such as pillared clay have been proposed in which an interlayer pillar is provided between layers of a layered compound such as clay mineral. (Chemical Review, p.
39-47, No. 21, 1994, edited by The Chemical Society of Japan).
Such a pillar compound is one in which an organic ion, a polynuclear inorganic ion, or the like is introduced between layers as a pillar precursor, and a space similar to a pore is formed by cross-linking between layers. By controlling various reaction conditions, pore diameters up to about 2 nm have been obtained. However, in the case of this pillar compound, although the adsorption amount of gas molecules is improved, there is a problem in that the catalytic ability and adsorption function for high molecular weight compounds and the like are low.

In recent years, for the purpose of solving the above-mentioned problems, a method has been proposed in which the layer interval of the layered silicate is widened by intercalation of a cationic surfactant by ion exchange (JP-A-4-238810). Gazette). According to this proposal, the pore size distribution is 20 to 50 nm.
Since a crystalline porous material having uniform mesopores can be obtained, it can be used as a selective catalyst or adsorbent for high molecular weight organic compounds and the like having a molecular size falling within this range. However, in the case of this proposal, there is a problem that the catalytic ability and adsorption function for low molecular weight gas molecules, and the function as an oil absorption carrier requiring a very large adsorption space are low.

On the other hand, an amorphous porous material (silica gel, alumina, etc.) is not uniform in composition and chemical properties as compared with a crystalline porous material, but on the other hand, various particle morphologies can be controlled. Such an amorphous porous material is generally prepared by a sol-gel method, and an organic substance is often used as a template for controlling the structure thereof.For example, a molecular aggregate of an ionic surfactant is used as a template, and A method for producing a porous hexagonal columnar body (honeycomb porous body) has been proposed (J. Am. Chem. Soc., 114, 10834).
-10843 (1992), Tokuhyo 5-503499). According to this proposal, various porous materials can be prepared by combining the surfactant to be used and the charge of the counter ion, and in any case, the porous material precursor (metal oxide) is formed on the surface of the ionic molecular assembly. The regular structure is formed by the progress of polycondensation of the material particle precursor). The amorphous porous material obtained in this manner has a large specific surface area, a high structural uniformity, and a selective catalytic ability and an adsorption function, but similar to the above proposal, it has a low molecular weight. There is a problem that the catalytic ability and adsorption function for gas molecules, and the function as an oil absorption carrier requiring a very large adsorption space are low. In addition, there is a manufacturing disadvantage that the removal of the mold is difficult.

Therefore, in order to solve the above problems, a method for preparing an amorphous porous material using a molecular assembly of non-ionic surfactant having no electric charge as a template has been proposed (Science, 269, 1242). -1244 (19
95), Nature, 378, 366-368 (19).
95)). These proposals are to obtain a porous body in which the morphology of liquid crystal is maintained by hydrolyzing and polycondensing a metal alkoxide in a liquid crystal phase prepared using a nonionic surfactant. According to these proposals, a mesoporous material having a uniform hexagonal (hexagonal) or plate (lamellar) pattern can be obtained. In this case, the pore diameter of the porous material is the molecular aggregation of the surfactant. In principle, a body larger than the body size could not be obtained, and the problem of difficulty in removing the template could not be solved.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel amorphous porous material having a wide pore size distribution and a method for producing the same so as to be sufficiently applicable in various fields of use. And

[0008]

Means for Solving the Problems and Modes for Carrying Out the Invention The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, the surfactant used as a template for producing an amorphous porous material by the sol-gel method Bicontinuous (bic) in which both the water phase and the oil phase obtained by putting oil between the hydrophobic groups of the molecular assembly are alternately continuous in layers.
ontinous) type microemulsion structure,
Alternatively, a novel amorphous pore having a wide pore size distribution in which micro, meso, and macro pores are distributed according to the fractal rule is obtained by using as a template a liquid crystal in which oil is sandwiched between layers of ordered structure composed of a surfactant and an aqueous system. Since the body can be obtained, and in this case, the distance between the water phases can be greatly adjusted only by adjusting the kind and amount of the oil phase, the crystalline porous body is provided with large macropores. The present inventors have found that it is possible to synthesize a carrier and have completed the present invention.

That is, according to the present invention, the pore size is 0.35 to 2n.
m, micropores, 2 to 50 nm, mesopores, 5
Amorphous porous body characterized in that macropores having a size of 0 nm to 1000 μm are distributed according to the fractal rule, and a pore diameter of 0.35 to 2n according to the sol-gel method.
m, micropores, 2 to 50 nm, mesopores, 5
A method for producing an amorphous porous body comprising a continuous structure having a porous structure in which macropores having a size of 0 nm to 1000 μm are distributed according to a fractal rule, which comprises a surfactant, a cosurfactant, oil, water or an inorganic salt solution. , Or a surfactant and oil and water or inorganic salt water, the water or inorganic salt aqueous phase as a continuous bilayer microemulsion or liquid crystal to form a continuous layer, and the continuous layer contains a metal compound. , A gel forming step of hydrolyzing and polycondensing a metal compound in a continuous layer, and a demolding step of removing the oil, surfactant, cosurfactant and inorganic salt in the mold by degassing and drying and heating this gel. And a firing step to obtain the amorphous porous body by firing the gel from which the template has been removed. To provide a method of manufacturing an amorphous porous body, wherein the door.

The present invention will be described in more detail below. The amorphous porous material of the present invention has a pore size of 0.35 to 2n.
m micropores, 2 to 50 nm mesopores, 50 nm to
The feature is that macropores of 1000 μm are distributed according to the fractal rule. That is, the amorphous porous material of the present invention is different from the conventional layered silicate having uniform pores prepared by using the above-mentioned conventional pillared clay or surfactant molecular aggregate alone as a template, and the like. It has a wide pore size distribution from pores to macropores.

More specifically, the porous body of the present invention has, when viewed macroscopically, a curved pie section or a half-cut cabbage section in which a plurality of plate-shaped wall bodies are layered and overlapped in layers. In addition to having a layered macro structure in which macropores are formed between these wall bodies, each wall body forming the above layered macro structure also has a large number of layers in a state in which the plate-like wall bodies are similarly partially curved. Plate-like wall bodies that overlap each other and have a layered mesostructure in which mesopores are formed between these wall bodies, and each wall body that forms this layered mesostructure is partially curved in the same manner as described above. The porous body of the present invention is a layered aggregate of the first wall body (microwall body) having the layered microstructure as described above, which has a layered microstructure in which micropores are formed and are superposed in multiple layers. Has a layered mesostructure consisting of Multi-layered structure of micro, meso, and macro in which the second wall body (meso wall body) is further assembled in layers to form a third wall body (macro wall body), and the third wall body is assembled in layers. Is to have. Conceptually, it has a structure as shown in FIG. That is, in FIG. 1, 1 is a macro wall body assembly, 2 is a macro wall body forming the macro wall body body 1, 3 is a macropore formed between the macro wall bodies 2,
Reference numeral 11 denotes a meso wall assembly that constitutes the macro wall 2,
2 is a meso wall body forming this meso wall body assembly 11, 13
Is the mesopores formed between the meso-walls 12, and 21
Is a micro wall assembly that constitutes the meso wall 12, 22
Is a micro wall body that forms the micro wall body assembly 2;
Reference numeral 3 is a micropore formed between the microwalls 22. Specifically, the porous body of the present invention has a shape structure as shown in the micrographs of FIGS.

Therefore, the micropores, mesopores, and macropores have shapes substantially similar to each other, and the pore shape includes a circular cross section, an elliptical shape, a polygonal shape, etc. A long hole shape having appropriate corner portions (uneven portions) is formed in a three-dimensional net shape. The pore size of each pore is
It means the minimum diameter (minimum distance) of the three-dimensional pore size. Here, the distribution ratio of each pore (volume ratio of each pore) is not particularly limited, and varies depending on the application of the porous body, usage method, etc., but usually the micropore volume obtained from the nitrogen adsorption isotherm curve. / Mesopore volume ratio is 1/100 to 100/1, and the Dollmore & Heal method (J. appl. Chem., 14, 109 (196).
4)) the micropore volume is 0.01-0.6 ml /
g, macropore volume by mercury porosimetry is 0.1
It is preferably in the range of 50 ml / g, particularly the micropore volume / mesopore volume ratio is 1/10 to 10/1, the micropore volume is 0.1 to 0.3 ml / g, and the macropores are It is more preferable that the volume is in the range of 1 to 30 ml / g. Outside of the above range, it may be difficult to use as a catalyst or adsorption carrier for a wide range of compounds.

Here, the self-similarity based on the fractal distribution refers to a property that when a part of a figure having a structural unit is enlarged, there is a structural unit that overlaps with a larger structural unit before the enlargement. In the case of, it can be easily quantitatively shown as the surface fractal dimension from the measurement of the figure or the adsorption of gas (Chemical, 45, No. 8, 52).
5 to 528 (1990)). In the case of the amorphous porous material of the present invention, when its cross-sectional structure is observed under a microscope, the above-mentioned
As described above, for example, when observed on the order of 10 μm, a regular array of macropores 3 is recognized as a porous structure of a continuous structure, and further on the order of 100 nm, the regular array of mesopores 13 is on the order of 1 nm. A regular array of micropores 23 is observed. The fractal dimension cannot be determined in a porous structure having only a wide distribution of pores without such regularity, and an aggregate in a disordered state is formed. It is clearly distinguished from an amorphous porous body. In the case of the amorphous porous material of the present invention, the value of the fractal dimension is not particularly limited, but considering the characteristics as an adsorption carrier, the fractal dimension is obtained from the count of the pore diameter of the particle cross section. When evaluated as a cross-sectional fractal dimension, a value of about 1.0 to 1.9 is suitable.

The amorphous porous material of the present invention is particularly preferably a metal oxide.
Can be formed. In this case, the metal oxide is Si
O_Two, ZnO, TiO_Two, Al_TwoO_Three, ZrO_Two, MnO ,
GeO_Two, Ga_TwoO_Three, In_TwoO_Three, SnO_Two, Fe_TwoO_Three, C
r_TwoO_Three, Bi_TwoO_Three, V_TwoO_FiveSingle metal oxide such as SiO, SiO
_Two-ZnO, SiO_Two-TiO_Two, Al_TwoO_Three-SiO_Two, S
iO_Two-Fe_TwoO_ThreeComplex metal oxides such as
If it can be formed by the manufacturing method described below,
It is not limited to these metal oxides.

Since the amorphous porous material of the present invention has a wide pore size distribution, it has an excellent function as an adsorption carrier and is excellent in the durability of the function, and is a reaction catalyst from a low molecular weight compound to a high molecular weight compound. It can also be used as an adsorption carrier,
In particular, since these pores are distributed according to the fractal distribution, if this is used as an adsorption carrier, the material structure has self-similarity, so that an adsorption surface with continuous regularity can be provided, and a separating agent, etc. When used as, it is possible to separate substances having a wide range of molecular weight with high resolution. in this case,
Due to the presence of macropores having a large pore size, the function as an adsorption carrier becomes more excellent.

More specifically, the amorphous porous material of the present invention can exhibit excellent functions in industrial use due to the above structure. For example, particles having uniform pores can be used as an adsorption carrier, a gas or a liquid. When used as a catalyst for the reaction, clogging and the like are very likely to occur, whereas in the case of the amorphous porous material of the present invention, since it has a wide pore size distribution, it does not have such a problem and is excellent in sustainability. It is very useful because it can be used as an adsorption carrier or the like. Further, since adsorption sites having greatly different properties are obtained, a desiccant, a dehydrating agent, a catalyst carrier, a chromatographic carrier, an antifoaming agent, a foam suppressor, a chelating agent, a builder, a granular detergent granulating agent, an anti-caking agent, Used in the application fields of silica gel such as abrasives, thickeners, matting agents, deodorants, decolorizers, oil-absorption carriers, gas / liquid separation membranes, catalyst carriers such as exhaust gas, protein separation, immobilized enzymes Carrier, filtration agent, packing material for chromatography,
It exerts excellent functions as a highly durable and separable material in applications such as ion-selective electrodes, optical fiber preforms, and radioactive waste fillers.

Such an amorphous porous material of the present invention comprises a bicontinuous microemulsion formed by inserting an oil between the hydrophobic groups of a surfactant molecular assembly or a surfactant and an aqueous system. Using a liquid crystal in which oil is sandwiched between layers of ordered structure as a template, a metal compound is contained in a continuous layer formed by the aqueous phase, and a gel formation step of hydrolyzing and polycondensing the metal compound in the continuous layer, and this gel Degassing and drying, and heating, a mold removing step of removing oil in the mold, a surfactant, a cosurfactant and an inorganic salt,
It can be suitably produced by a production method comprising a step of firing the gel from which the template has been removed to obtain an amorphous porous body.

That is, the first step of the production method of the present invention comprises a surfactant, a cosurfactant, oil and water or an inorganic salt water, or a surfactant and an oil and water or an inorganic salt water. Is a reaction step in which a bicontinuous microemulsion or liquid crystal forming a continuous layer is used as a template, the above-mentioned continuous layer contains a metal compound, and the metal compound is hydrolyzed and polycondensed in the continuous layer.

Here, as the surfactant, any of nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants can be used. Specifically, for example, as a nonionic surfactant,
Alkyl polyoxyethylene ether, alkylphenyl polyoxyethylene ether, alkyl polyoxyethylene polyoxypropylene ether, higher fatty acid alkanolamide or its ethylene oxide adduct, alkyl amine oxide, polysaccharide derivative, fatty acid ethoxylate, alkyl amine, sorbitan Derivatives and the like can be exemplified, but among these, particularly widely and generally used ethylene oxide adducts are preferably used. Most of the ethylene oxide adducts are a mixture of those having different addition mole numbers, but in the present invention, those having a very narrow distribution are particularly suitable.

As the anionic activator, soap,
Carboxylic acid derivatives (ethoxy, ester, amide, etc.),
Examples thereof include alkyl sulphate, alcohol ether sulphate, sulfuric acid alkanolamide ethoxylate, alkyl polyoxyethylene salt, olefin sulfonate, alkyl phosphate ester, sulphosuccinate, sulphosuccinamide and tauride.

Furthermore, examples of the cationic activator include quaternized alkylammonium salt and alkylimidazoline salt, and examples of the amphoteric activator include alkylbetaine and alkylglycinate.

The blending amount of the surfactant in the production method of the present invention can be variously selected depending on the kind of the intended bicontinuous microemulsion or liquid crystal, but in the case of the usual bicontinuous microemulsion. , 0.5 to 20% by weight based on the total amount of the template forming material and the metal compound, and 10 to 5 in the case of liquid crystal.
0% by weight. Outside the above range, it may be difficult to form the mold of the present invention.

Next, the type of oil used as the oil phase that forms the partition walls of the mold is not particularly limited as long as it can maintain the partition structure, and such oils are
For example, animal and vegetable oils, paraffin hydrocarbons, naphthene hydrocarbons, terpene oils, aliphatic carboxylic acid esters, aromatic oils and the like can be mentioned. Among them, from the viewpoint of template removal, room temperature to 100 ° C. Those having a boiling point in the range are particularly preferable. In the case of the production method of the present invention, the pore size distribution can be adjusted by adjusting the type and amount of the oil phase, and the addition amount of these oils is variously selected depending on the target pore size distribution and the like. However, it is usually preferable that the weight ratio of aqueous phase (aqueous solution phase containing a metal compound that is a porous body precursor) / oil phase is in the range of 1/9 to 9/1, and particularly the pore diameter is 100 nm or more. In order to obtain the continuous structure in which the macropores are distributed, it is preferably 3/7 to 7/3. If the amount of oil added is too large, it may be difficult to obtain a stable bicontinuous microemulsion or liquid crystal.

Here, in producing a mold in the production method of the present invention, for example, when a bicontinuous microemulsion is produced by using a nonionic surfactant as a surfactant, the HLB value thereof depends on the temperature. By utilizing the change, a bicontinuous microemulsion can be produced in the vicinity of the phase inversion temperature of a ternary system of a surfactant, oil and water or inorganic salt water. On the other hand, when an ionic surfactant is used, its hydrophilicity is very high, and therefore a cosurfactant is added,
Furthermore, it is necessary to adjust the addition amount of the inorganic salt in the aqueous phase to create a balanced state of the three-component system. When an ionic surfactant having high lipophilicity is used, a balanced state can be created by adjusting the temperature without using a cosurfactant or an inorganic salt.

Therefore, in the production method of the present invention, by adding a cosurfactant or an inorganic salt to the aqueous phase, if necessary, a surfactant is added to the system comprising the surfactant, the oil phase and the aqueous phase. It is possible to preferably manufacture a continuous micro-emulsion or a liquid crystal mold.

In the production method of the present invention, the cosurfactant is used not only for adjusting the HLB value of the surfactant as described above, but also for enhancing the solubility of the poorly water-soluble metal compound in water. It is also used as an agent. Therefore, as the cosurfactant, if it can be used as a HLB control of the surfactant and a solubilizing agent of the precursor of the metal oxide gel in water,
The type is not particularly limited, but neutral low molecular weight compounds having an oxygen atom and having a molecular weight of 1000 or less are usually used. Among these, polyhydric alcohols such as glycerin, polyethylene glycol, and sorbitol are particularly preferable.
Monohydric alcohols such as methanol, ethanol, isopropanol and butanol are preferably used. When a cosurfactant is added, the amount of the cosurfactant added can be appropriately selected, but it is usually preferable that the weight ratio of surfactant / cosurfactant is 100/1 to 1/1. The weight ratio of metal compound / cosurfactant is preferably 100/1 to 1/10. If the amount of the cosurfactant added is too large, precipitation of the surfactant or the like may occur.

As described above, the inorganic salt added to the aqueous phase is mainly used as an HLB regulator of an anionic surfactant, and such an inorganic salt is used as an HLB regulator. The type is not particularly limited as long as it has the function of, and examples thereof include sodium chloride, potassium chloride, and sodium sulfate. The addition amount of the inorganic salt is also appropriately selected, but usually the surfactant / inorganic salt weight ratio is 100 /
It is preferable to set it to 1 to 1/10, particularly 4/1 to 1/10. If the addition amount of the inorganic salt is too small, a microemulsion may not be formed in some cases, and if it is too large, precipitation of the surfactant or the inorganic salt may occur.

Next, as the metal compound, those generally used as a precursor of a metal oxide gel in the sol-gel method can be used. For example, organic compounds such as metal alkoxide, metal acetylacetonate, metal carboxylate and the like can be used. Examples thereof include metal inorganic compounds such as nitrates, oxychlorides and chlorides, and oxide fine particles such as fumed silica. Among them, general formula M (OR) _n (where M is a metal element) , R is an alkyl group, and n is the oxidation number of the metal element.), A metal alkoxide represented by the formula (I) is preferably used. More specifically, as the metal alkoxide, for example, “science of sol-gel method”, page 20, Table 3 .2
(Sakuka Sakuo, Agne Jofusha, Ltd., 1990), silicon alkoxide, titanium alkoxide, manganese alkoxide, aluminum alkoxide, zirconium alkoxide, germanium alkoxide, gallium alkoxide, indium alkoxide, tin. An alkoxide etc. can be mentioned. The alkoxy group preferably has 6 or less carbon atoms, and methoxy, ethoxy and isopropoxy groups are particularly preferably used.

Specific examples of suitable metal alkoxides include tetraethoxysilane, aluminum isopropoxide, titanium isopropoxide, tetramethoxysilane, tetrabutoxysilane, zirconium methoxide and manganese isopropoxide. it can. Therefore, by using such a metal compound, a metal oxide gel is formed by the above-mentioned hydrolysis / polycondensation step of the metal oxide, and by firing the metal oxide gel, a metal oxide gel is formed. The amorphous porous material of the invention can be obtained.

The metal compound is preferably added in an amount of 1 to 50% by weight based on the water phase in the mold. If the amount of the metal compound added is too small, the porous structure may not be obtained, and if it is too large, the hydrolysis may not proceed sufficiently.

In the production method of the present invention, a bicontinuous microemulsion or liquid crystal is formed by using the above-mentioned surfactant or the like, and this is used as a template. That is,
Microemulsions are generally spherical and have a particle size of 1
There is a transparent to translucent emulsion of 0 to 100 nm and a bicontinuous microemulsion in which a surfactant is arranged in layers and an aqueous phase and an oil phase are sandwiched between the layers, and the latter is used in the production method of the present invention. It is what is done. A method for producing such a bicontinuous microemulsion has already been reported (for example, HETEROGENEOUS CHEMISTR).
Y REVIEWS, Vol 1, 145-157 (1
994)), the surfactant horizontally gathered at the interface between the oil phase and the water phase to be used can be prepared by alternately sandwiching the water phase and the oil phase.

Specifically, for example, Japanese Patent Laid-Open No. 15594/1989
No. 1, J.I. Phys. Chem. 1986, 90,
No. 671-677, a bicontinuous microemulsion is prepared by mixing a surfactant with an aqueous phase and an oil phase. In this case, the aggregated surfactant is used. In the case where the interface has a curvature due to the size of the hydrophilic group and the hydrophobic group, the temperature is adjusted or the cosurfactant or inorganic is used to make the interface a bicontinuous type in which the interface is horizontal. Add salt. In this case, the temperature control is set according to the kind of the surfactant (HLB value), and the temperature is set so as to obtain a stable bicontinuous microemulsion or liquid crystal without impairing the stability of the surfactant and the like. Usually, it is preferable to adjust the temperature in the range of 0 to 100 ° C.

Here, when a bicontinuous microemulsion is formed, the solution shows a transparent to blue transparent state with the naked eye, and the optical anisotropy (from the liquid crystal origin) is observed by a polarizing microscope. It is a solution in which no pattern) is seen, and has a structure in which both the water phase and the oil phase are continuous. Therefore, by observing whether the solution being prepared is transparent or blue and transparent, and whether the solution reacting as a template by polarization microscope observation exists as an intermediate phase in a three-phase separated state of an excess aqueous phase and an excess oil phase, Alternatively, preparation is performed while confirming that the composition of the intermediate layer can be specified even in a homogeneous single-phase solution state, and if necessary, the temperature is appropriately adjusted as described above or a cosurfactant or an inorganic salt is added. .

Further, the liquid crystal used as a template in the production method of the present invention has various liquid crystal structures (eg Physi) formed by a generally widely known surfactant aggregated in an aqueous system.
csReports (Review Section
of Physical Letters) Vol. 5
7, 1, 1 to 46 (1980)),
It can be prepared by sandwiching oil between the layers of the ordered structure.

Specifically, the above-mentioned Physics Rep
orts, Liquid Crystals & Pl
asic Crystals Vol. 1, Elli
sHorwood Pub. , Chap. 5: pp. 1
99-287 (1974) and the like are used to prepare a liquid crystal in which an oil is sandwiched between layers of a regular structure of a surfactant and an aqueous system by a known means, and the surfactant, water and the oil are mixed. At the same time, similarly to the above, the liquid crystal can be adjusted to a state having a preferable structure by appropriately adjusting the temperature, adding a cosurfactant, and an inorganic salt, if necessary. The solutions in which the liquid crystals can be prepared vary from macroscopically transparent to cloudy, but by observing with a polarizing microscope, the patterns derived from the liquid crystals are observed, so the liquid crystals can be easily observed with a polarizing microscope. The existence of the structure can be confirmed.

Here, in the case of the production method of the present invention, since the bicontinuous microemulsion or liquid crystal is used as a template, the pore size distribution is adjusted only by adjusting the type and amount of the oil phase as described above. It is possible to synthesize an amorphous porous material with large macropores, which was difficult with a crystalline porous material.However, in the case of liquid crystal, it is possible to synthesize an oil phase between layers due to its high structural property. Since the space between the two is slightly narrowed, it is preferable to use liquid crystal as the template when it is desired to reduce the proportion of relatively large pores in the resulting porous body.

In the reaction step of the production method of the present invention, the metal compound is contained in the continuous layer formed by the aqueous phase of the template obtained as described above, and the metal compound is hydrolyzed and polycondensed in the continuous layer. By doing so, a gel is produced from the sol, and in this step, an acid (hydrochloric acid or the like) which is a catalyst can be used for controlling the hydrolysis rate, if necessary. Examples of such a catalyst include inorganic and organic acids and alkalis, and hydrochloric acid, sulfuric acid, acetic acid, ammonia and the like are particularly preferably used. It is usually preferable to adjust the amount of these catalysts to be added to the hydrolysis rate of the metal compound, and it is not necessary to add them in the case where vigorous hydrolysis occurs even without using a catalyst, and the reaction is relatively mild. However, it is preferable to determine the addition amount in consideration of the gelation time. In addition, hydrolysis
The reaction conditions for the polycondensation can be carried out under the usual conditions for each metal compound in the conventional sol-gel method, for example, in the temperature range of 0 to 100 ° C. which is the template forming temperature so as not to impair the stability of the template. By leaving the system for several hours to several days, the metal compound in the aqueous phase can be hydrolyzed and polycondensed to obtain a metal oxide gel.

In the second step of the production method of the present invention, the gel is degassed and dried and heated to remove oil in the mold, a surfactant,
It is a template removing step of removing the cosurfactant and the inorganic salt. Degassing and drying are preferably carried out over a rather long period of time, for example, 1 to 5 hours by ordinary vacuum drying or supercritical drying. If the oil phase has a low boiling point, such degassing is performed. It can be quickly removed only by drying. Further, after drying, if a step of washing the gel with water and / or an organic solvent is added in order to remove surfactants, inorganic salts, etc. in advance, good results will be obtained because impurities are further removed. be able to. In particular, when a manufacturing method using a liquid crystal as a mold is adopted, a large amount of the surfactant is used, so that the necessity of the cleaning step is increased. Here, as the organic solvent used for washing the gel, those used in the template removing step of the conventional sol-gel method can be used, and examples of such an organic solvent include acetone and the like. Then, by heating,
It is possible to completely remove the template by carbonizing the surface active agent, the inorganic salt, the trace amount of the organic matter and the like before the firing step.

Next, the third step of the manufacturing method of the present invention is a firing step of firing the metal oxide gel from which the template has been removed. The firing conditions in the firing step can be determined in the same manner as in the conventional sol-gel method, and it is usually preferable to perform firing at a firing temperature of about 300 to 800 ° C. for about 3 to 5 hours.
If the firing temperature is too high, the layered structure may be broken, and if it is too low, sufficient micropores or mesopores may not be generated. The firing environment is not particularly limited, but it can be performed in an atmosphere of an inert gas such as nitrogen or in an air atmosphere.

[0040]

Since the amorphous porous material of the present invention has a wide pore size distribution from micropores to macropores, it can be sufficiently applied in various fields of use, and particularly has large macropores. It also excels in the function as an oil absorption carrier that requires a very large adsorption space. Also,
According to the production method of the present invention, it is possible to easily and reliably produce such an amorphous porous body, and synthesize an amorphous porous body having large macropores, which was difficult with a crystalline porous body. You can

[0041]

EXAMPLES The present invention will be described in more detail below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 3] Polyoxyethylene lauryl ether was used as the nonionic surfactant, and synthesis was performed using tetraethoxysilane (TEOS) as a precursor.

That is, the water phase was adjusted to have a composition shown in Table 1 by weight ratio of water / TEOS / glycerin / hydrochloric acid of 86.2.
/10.0/0.6/3.2 as a mixture, the oil phase is isooctane, and the weight ratio of nonionic surfactant / water phase / oil phase is at the template preparation temperature shown in Table 1. Of 1 / 9.5 / 9.5 to obtain a bicontinuous microemulsion template in which the precursor is incorporated into the intermediate water layer in a three-phase separated state, and further, under the above temperature conditions. Stored for 18 hours in the intermediate water layer, the precursor was hydrolyzed and polycondensed in the intermediate water layer to obtain an intermediate layer in which SiO ₂ was gelled, and then this intermediate layer was taken out.
This intermediate layer was supercritically dried, heated at 500 ° C. for 5 hours under a nitrogen stream, carbonized, and further calcined at 500 ° C. for 4 hours to obtain amorphous SiO ₂ porous bodies of Examples 1 to 3. The surfactant concentration in the table is the concentration based on the whole surfactant / water phase / oil phase. In addition, FIGS. 2 to 11 show SEM images obtained by observing the cross section of the porous body of Example 1 by using a scanning electron microscope and sequentially enlarging the magnification. From these figures, it can be seen that the porous body of Example 1 has a thickness of 50 nm to 1000 μm, especially 50 nm
It was found that the micropores had a size of 10 μm, and by successively enlarging the magnification, a self-similar continuous structure as shown in the conceptual diagram of FIG. 1 was also found in the region of the macropores. Further, FIG. 15 shows adsorption isotherms of nitrogen on the porous body of Example 1. From this figure, from the change in the adsorption amount at each relative pressure (P / P ₀ ), 0.3
Micropores 5~2nm (P / P ₀ corresponds to 0.1 or less) and 0.1 is mesopores (P / P ₀ of 2~50nm
Corresponding to 0.9). Further, it was confirmed from the same microscopic observation and adsorption isotherm of the porous bodies of Examples 2 and 3 that they had similar micro, meso and macro pores.

[Examples 4 and 5] Table 1 in Example 1
The nonionic surfactant / water phase / oil phase were added at a weight ratio of 4/8/8 (Example 4) and 6/7/7 (Example 5), respectively, so as to obtain the surfactant concentration shown in. Amorphous S of Examples 4 and 5 was obtained by the same procedure as in Example 1 except that a lamellar liquid crystal template incorporating the precursor was obtained by mixing.
An iO ₂ porous body was obtained. These porous bodies of Examples 4 and 5 also
By the same microscope observation and adsorption isotherm as in Example 1, the same distribution of macropores of 50 nm to 1000 μm was recognized, and it had micropores of 0.35 to 2 nm and mesopores of 2 to 50 nm. Was confirmed.

[Comparative Examples 1 to 4] In Example 1, except for the oil phase, the aqueous phase component was left as it was, and the concentration of the nonionic surfactant was 1%, 20% and 50% based on the total weight. And 70%, respectively, except that a micelle template (Comparative Examples 1 and 2) containing only a precursor and a hexagonal type liquid crystal template (Comparative Example 3) and a lamella type liquid crystal template (Comparative Example 4) respectively containing a precursor were obtained. The amorphous SiO ₂ porous bodies of Comparative Examples 1 to 4 were obtained by the same operation as in the above example. FIG. 12 shows a TEM image of a cross section of the amorphous SiO ₂ porous body of the reference example obtained under substantially the same conditions as in Comparative Example 1.

[Comparative Examples 5 and 6] In Example 1, the W / O type microemulsion template having the same composition but having the template preparation temperature of 70 ° C. and the precursor incorporated therein was set to 60 ° C. O / W with precursor incorporated by
Amorphous SiO ₂ porous bodies of Comparative Examples 5 and 6 were obtained by the same operation as in Example 1 except that the type microemulsion template was obtained. 13 and 14 show SEM images of the cross section of the porous body of Comparative Example 6.

The respective pore volumes of the porous bodies of the above Examples and Comparative Examples were measured by the following measuring method, and the fractal dimension of the cross section was determined by the following evaluating method. The results are also shown in Table 1. <Measurement Method of Pore Volume> The surface area of the porous body was determined from the BET surface area (m ² / g) by measuring the adsorption isotherm of nitrogen, and the result was further calculated by the Dollimore & Heal method (J. appl. Chem., 14, 109-114
(1964)) to determine the micropore area and the mesopore area, and the value of the obtained area was converted into each pore volume. The pore volume obtained by such a method is based on the principle that when a mesopore is present, a larger amount of adsorption is observed than on a flat surface due to capillary condensation. In addition,
The macropore volume was determined by mercury porosimetry. <Evaluation method of cross-sectional fractal dimension> The cross-sectional fractal dimension of macropores is calculated by dividing a particle cross-sectional image of an electron microscope observed at different magnifications into a set of small squares, and counting them by a box count method (for example, “fractal dimension”). , P1
8-20, 1986, Asakura Shoten). From the nitrogen adsorption isotherm, it was confirmed that the dimensions of the pores smaller than that were almost the same, and the average value was shown.

[0048]

[Table 1]

[Brief description of drawings]

FIG. 1 is a conceptual sectional view of a porous body for sequentially explaining the pore size distribution of the amorphous porous body of the present invention.

FIG. 2 SE of a cross section of the amorphous porous material of Example 1
It is an M photograph.

FIG. 3 is an SE of a cross-section of the amorphous porous material of Example 1.
It is an M photograph.

FIG. 4 is an SE image of a cross section of the amorphous porous material of Example 1.
It is an M photograph.

FIG. 5 SE of a cross section of the amorphous porous material of Example 1
It is an M photograph.

FIG. 6 SE obtained by photographing a cross section of the amorphous porous material of Example 1.
It is an M photograph.

[FIG. 7] SE obtained by photographing a cross section of the amorphous porous material of Example 1.
It is an M photograph.

FIG. 8 is an SE image of a cross section of the amorphous porous material of Example 1.
It is an M photograph.

FIG. 9 is an SE image of a cross section of the amorphous porous material of Example 1.
It is an M photograph.

10 is a photograph S of a cross section of the amorphous porous material of Example 1. FIG.
It is an EM photograph.

11 is a photograph S of a cross section of the amorphous porous material of Example 1. FIG.
It is an EM photograph.

FIG. 12 is a TE image of a cross section of an amorphous porous material of Reference Example.
It is an M photograph.

13 is a photograph S of a cross section of the amorphous porous body of Comparative Example 6. FIG.
It is an EM photograph.

14 is a photograph S of a cross section of the amorphous porous body of Comparative Example 6. FIG.
It is an EM photograph.

15 is an adsorption isotherm of nitrogen for the amorphous porous material of Example 1. FIG.

[Explanation of symbols]

 3 Macropores 13 Mesopores 23 Micropores

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyoko Aikawa 2-18-4 Nishi, Toride-shi, Ibaraki (72) Inventor Katsumi Kaneko 6-25-1 Aobadai, Ichihara-shi, Chiba

Claims (2)

[Claims] 1. A micropore having a pore diameter of 0.35 to 2 nm, a mesopore having a pore diameter of 2 to 50 nm, and 50 nm to 100.
An amorphous porous body characterized in that macropores having a size of 0 μm are distributed according to a fractal rule. 2. A method for producing an amorphous porous material by the sol-gel method, which comprises a surfactant, a cosurfactant, oil and water or an inorganic salt water, or a surfactant and an oil and water or an inorganic salt water. Alternatively, a gel forming step in which the inorganic salt aqueous phase forms a continuous layer using a bicontinuous microemulsion or liquid crystal as a template, and the continuous layer contains a metal compound, and the metal compound is hydrolyzed and polycondensed in the continuous layer. And deaeration drying and heating this gel, a mold removal step of removing oil in the mold, surfactant, cosurfactant and inorganic salt, and a baking step of baking the gel from which the template has been removed. A method for producing a characteristic amorphous porous body.