JP2007045692A - Method of manufacturing mesoporous silica and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing mesoporous silica using a surfactant associate structure as a template under an electrolyte-free condition. <P>SOLUTION: The mesoporous silica is derived from following (A) and (B) component. (A) is a nonionic surfactant. (B) is a water-soluble silicate monomer expressed in general formula (1): Si-(OR<SP>1</SP>)<SB>4</SB>(in the formula, R<SP>1</SP>expresses polyhydric alcohol residue). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement in mesoporous silica and a method for producing the same, and in particular, a method for producing mesoporous silica using an association structure of a surfactant as a template.

  Porous materials (porous materials) are usually classified as microporous, those having a thickness of 2 nm or less, mesoporous, those having a thickness of 50 nm or more, and macroporous, depending on the pore diameter. Mesoporous silica produced by a template method using a surfactant micelle as a template has a high specific surface area and a uniform pore diameter, and is applied to various fields because of its structural characteristics. To date, methods for synthesizing mesoporous silica using various surfactants have been established (see Patent Document 1 and Non-Patent Documents 1 to 4 below). In addition, nonionic surfactants easily generate self-assembled aggregates such as micelles and liquid crystals under electrolyte-free conditions, so mesoporous silica using this as a template should also be electrolyte-free in principle. It is possible. This is expected to be applied to applications that dislike ionic impurities such as electronic materials.

  However, alkoxysilane (silicon alkoxide), which is a silicate monomer used in the conventional template method, is an oil-soluble substance, and since it is difficult to hydrolyze an alkoxy group at neutrality, it is practically acidic or basic. Under the above conditions, if necessary, a lower alcohol as a solubilizing agent is added to promote hydrolysis to generate a silanol group that is a condensable functional group. For example, inorganic silicate monomers such as water glass, colloidal silica, smoked silica, and precipitated silica tend to undergo self-condensation at neutrality. Used for reaction with chemicals. For this reason, the conventional silicate monomer has a problem that it cannot fully utilize the advantage of the electrolyte-free aggregate formation of the nonionic surfactant for the production of mesoporous silica.

JP 2001-261326 A Sakai et al., Materials Integration, 2000, Vol. 10, No. 13, p. 50 Huo et al., Chemistry of Materials (Chem. Mater), 1994, Vol. 6, p. 1176 to 1191 Hironobu Kunieda et al., “Latest Functions of Surfactants and Amphiphilic Polymers”, CMC Publishing, June 2005, Chapter 5 “1. Development of mesoporous materials by template method” Terasaki, “MESOPORUS AND RELATED NANO-STRUCTUREDTERIALS”, ELSEVIER, 2004

  The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to provide a method for producing mesoporous silica under the condition of electrolyte-free conditions using a surfactant aggregate structure as a template. That is.

  As a result of intensive studies by the inventor to solve the problems described in the preceding paragraph, a nonionic surfactant and a water-soluble silicate monomer having a specific structure are used and reacted under neutral conditions. The inventors have found that mesoporous silica can be prepared with the present invention, and have completed the present invention.

That is, the mesoporous silica according to the present invention is derived from the following components (A) and (B).
(A) Nonionic surfactant (B) Water-soluble silicate monomer represented by the following general formula (1) Si- (OR ¹ ) ₄ (1)
(In the formula, R ¹ is a polyhydric alcohol residue.)

In the mesoporous silica, (B) R ^{1 of the} water-soluble silicate monomer is ethylene glycol residue, propylene glycol residue, butylene glycol residue, glycerin residue, or condensation of ethylene glycol, propylene glycol, butylene glycol, glycerin. Any of the residues of the product is preferred.

  The mesoporous silica composite according to the present invention is derived from the components (A) and (B). The mesoporous silica outer shell according to the present invention is derived from the above components (A) and (B).

  Further, the method for producing a mesoporous silica composite according to the present invention comprises the above components (A) and (B) in water or a mixed solvent of water and an organic solvent compatible with water under neutral conditions. It is characterized by mixing.

In the method for producing the mesoporous silica composite, (B) R ^{1 of the} water-soluble silicate monomer is ethylene glycol residue, propylene glycol residue, butylene glycol residue, glycerin residue, or ethylene glycol, propylene glycol, butylene. It is preferably either a residue of a glycol or glycerin condensate.

  In the method for producing a mesoporous silica outer shell according to the present invention, the mesoporous silica composite obtained by the production method is washed with an acidic aqueous solution, water, an organic solvent compatible with water or an aqueous solution thereof, The nonionic surfactant of A) is removed.

  The method for producing mesoporous silica according to the present invention is characterized in that the mesoporous silica composite obtained by the production method or the mesoporous silica outer shell obtained by the production method is fired.

  According to the present invention, by using a water-soluble silicate monomer having a specific structure, it is possible to prepare mesoporous silica having high structure regularity by nonionic surfactant micelles under neutral conditions.

The mesoporous silica according to the present invention is derived from the following components (A) and (B).
(A) Nonionic surfactant (B) Water-soluble silicate monomer represented by the following general formula (1) Si- (OR ¹ ) ₄ (1)
(In the formula, R ¹ is a polyhydric alcohol residue.)

  The nonionic surfactant (A) used in the present invention is not particularly limited, and various nonionic surfactants exemplified below can be used. Typical examples include polyoxyethylene type nonionic surfactants, polyglycerin type nonionic surfactants, sugar ester type nonionic surfactants, etc., and these should be used alone or in combination of two or more. Can do.

  More specifically, for example, POE alkyl ether, POE alkyl phenyl ether, POE / POP alkyl ether, POE fatty acid ester, POE sorbitan fatty acid ester, POE glycerin fatty acid ester, POE castor oil or hydrogenated castor oil derivative, POE beeswax Examples include lanolin derivatives, alkanolamides, POE propylene glycol fatty acid esters, POE alkylamines, POE fatty acid amides, sugar fatty acid esters, polyglycerin fatty acid esters, and polyether-modified silicones. These can be used individually by 1 type or in combination of 2 or more types. “POE” means polyoxyethylene, and “POP” means polyoxypropylene, which may be described as follows.

  In the POE type nonionic surfactant, the alkyl group is an alkyl group of a saturated or unsaturated fatty acid having 6 to 22 carbon atoms. For example, a simple group such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and the like. In addition to these, fatty acids of natural composition such as coconut oil fatty acid, beef tallow fatty acid, hydrogenated beef tallow fatty acid, castor oil fatty acid, olive oil fatty acid, palm oil fatty acid, etc. May be an alkyl group. Further, the alkyl group may be a fluoroalkyl group in which hydrogen is substituted with fluorine at an arbitrary ratio. In the POE type nonionic surfactant, the POE condensation number is in the range of 1 to 50, more preferably in the range of 5 to 20.

The water-soluble silicate monomer (B) used in the present invention is represented by the above general formula (1). In the water-soluble silicate monomer represented by the general formula (1), R ¹ is a residue of a polyhydric alcohol, and is represented as a form in which one hydroxyl group in the polyhydric alcohol is removed. The water-soluble silicate monomer can usually be prepared by a substitution reaction between tetraalkoxysilane and a polyhydric alcohol, and R ¹ varies depending on the type of polyhydric alcohol used. When ethylene glycol is used, R ¹ becomes —CH ₂ —CH ₂ —OH.

R ¹ in the general formula (1) is, for example, ethylene glycol residue, diethylene glycol residue, triethylene glycol residue, tetraethylene glycol residue, polyethylene glycol residue, propylene glycol residue, dipropylene glycol residue. , Polypropylene glycol residue, butylene glycol residue, hexylene glycol residue, glycerol residue, diglycerol residue, polyglycerol residue, neopentyl glycol residue, trimethylolpropane residue, pentaerythritol residue, maltitol Examples include residues. Among these, it is preferable that R ¹ is any one of an ethylene glycol residue, a propylene glycol residue, a butylene glycol residue, and a glycerin residue.

More specifically, examples of the water-soluble silicate monomer (B) used in the present invention include Si— (O—CH ₂ —CH ₂ —OH) ₄ , Si— (O—CH ₂ —CH ₂ —CH _{2). -OH) 4, Si- (O-} CH 2 -CH 2 -CHOH-CH 3) 4, Si- (O-CH 2 -CHOH-CH 2 -OH) 4 , and the like.

  The water-soluble silicate monomer (B) used in the present invention can be prepared, for example, by reacting a tetraalkoxysilane and a polyhydric alcohol in the presence of a solid catalyst.

  The tetraalkoxysilane is not particularly limited as long as four alkoxy groups are bonded to a silicon atom. Examples of the tetraalkoxysilane used for the production of the water-soluble silicate monomer include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrapropoxysilane, and tetrabutoxysilane. Of these, tetraethoxysilane is most preferable from the viewpoint of availability and safety of reaction by-products.

  As an alternative compound of tetraalkoxysilane, mono, di, or trihalogenated alkoxysilane such as monochlorotriethoxysilane, dichlorodimethoxysilane, monobromotriethoxysilane, or the like, or tetrahalogenated silane such as tetrachlorosilane or the like may be used. However, since these compounds produce strong acids such as hydrogen chloride and hydrogen bromide in the reaction with polyhydric alcohols, corrosion of the reactor occurs, and separation and removal after the reaction are difficult. Therefore, it is hard to say that it is practical.

  The polyhydric alcohol is not particularly limited as long as it is a compound having two or more hydroxyl groups in the molecule. Examples of the polyhydric alcohol used in the production of the water-soluble silicate monomer include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexylene glycol, and glycerin. , Diglycerin, polyglycerin, neopentyl glycol, trimethylolpropane, pentaerythritol, maltitol and the like. Among these, it is preferable to use any of ethylene glycol, propylene glycol, butylene glycol, and glycerin.

  The solid catalyst is a solid catalyst that is insoluble in the raw material components, reaction solvent, and reaction product to be used, and has an acid site and / or a base site having activity for a substituent exchange reaction on a silicon atom. What is necessary is just solid. Examples of the solid catalyst used in the present invention include an ion exchange resin and various inorganic solid acid / base catalysts.

  Examples of the ion exchange resin used as the solid catalyst include acidic cation exchange resins and basic anion exchange resins. Examples of the resin that forms the base of these ion exchange resins include styrene-based, acrylic-based, and methacrylic-based resins, and functional groups that exhibit catalytic activity include sulfonic acid, acrylic acid, methacrylic acid, quaternary ammonium, And secondary amines. The substrate structure of the ion exchange resin can be selected from a gel type, a porous type, a bipolar type, and the like according to the purpose.

  Examples of the acidic cation exchange resin include Amberlite IRC76, FPC3500, IRC748, IRB120B Na, IR124 Na, 200CT Na (above, manufactured by Rohm and Haas), Diaion SK1B, PK208 (above, manufactured by Mitsubishi Chemical Corporation), Dow EX monosphere 650C, Marathon C, HCR-S, Marathon MSC (above, manufactured by Dow Chemical Co., Ltd.) and the like. Examples of the basic anion exchange resin include Amberlite IRA400J CL, IRA402BL CL, IRA410J CL, IRA411 CL, IRA458RF CL, IRA900J CL, IRA910CT CL, IRA67, IRA96SB (above, manufactured by Rohm and Haas), Dia Ion SA10A, SAF11AL, SAF12A, PAF308L (manufactured by Mitsubishi Chemical Corporation), Dow EX monosphere 550A, marathon A, marathon A2, marathon MSA (manufactured by Dow Chemical Company) and the like.

The inorganic solid acid / base catalyst used as the solid catalyst is not particularly limited. Examples of the inorganic solid acid catalyst include single metal oxides such as Al ₂ O ₃ , SiO ₂ , ZrO ₂ , TiO ₂ , ZnO, MgO, Cr ₂ O ₃ , SiO ₂ —Al ₂ O ₃ , SiO ₂ —TiO _2. , SiO ₂ —ZrO ₂ , TiO ₂ —ZrO ₂ , ZnO—Al ₂ O ₃ , Cr ₂ O ₃ —Al ₂ O 3, SiO ₂ —MgO, ZnO—SiO _{2 and} other complex metal oxides, NiSO ₄ , FeSO ₄ or the like of metal sulfates, metal phosphates such as _{FePO 4, H 2 SO 4 /} SiO 2 or the like immobilized sulfuric _acid, H ₂ PO 4 / SiO ₂ or the like immobilized phosphoric _acid, H ₃ BO ₃ / SiO ₂ immobilization boric acid etc., activated clay, zeolite, kaolin, natural mineral or layered compounds such as montmorillonite, AlPO ₄ - synthetic zeolites such as _{zeolite, H 3 PW 12 O 40 ·} 5H 2 , Such heteropoly acids such as _H 3 _PW 12 _{O 40} and the like. Examples of the inorganic solid base catalyst include single metal oxides such as Na ₂ O, K ₂ O, Rb ₂ O, Cs ₂ O, MgO, CaO, SrO, BaO, La ₂ O ₃ , ZrO ₃ , and ThO ₃ . , Na ₂ CO ₃ , K ₂ CO ₃ , KHCO ₃ , KNaCO ₃ , CaCO ₃ , SrCO ₃ , BaCO ₃ , (NH ₄ ) ₂ CO ₃ , Na ₂ WO ₄ .2H ₂ O, metal salt such as KCN, Na -Al ₂ O _3, K-SiO alkali metal supported metal oxide such as _2, Na-alkali metal-loaded zeolite such as _{mordenite, SiO 2 -MgO, SiO 2 -CaO} , SiO 2 -SrO, SiO 2 -ZnO, SiO _{2 -Al 2 O 3, SiO 2} -ThO 2, SiO 2 -TiO 2, SiO 2 -ZrO 2, SiO 2 -MoO 3, SiO 2 -WO, Al 2 _{O 3 -MgO, Al 2 O 3} -ThO 2, Al 2 O 3 -TiO 2, Al 2 O 3 -ZrO 2, ZrO 2 -ZnO, ZrO 2 -TiO 2, TiO 2 -MgO, ZrO 2 -SnO 2 And composite metal oxides.

  The solid catalyst can be easily separated from the product by a treatment such as filtration or decantation after completion of the reaction.

  In the production of the water-soluble silicate monomer, the temperature condition during the reaction is not particularly limited, but it is preferably performed under a temperature condition of 5 to 90 ° C. When the reaction is carried out at a temperature exceeding 90 ° C., there are problems in practical use such as durability of the reaction apparatus, and it is necessary to use a high boiling point solvent as a reaction solvent, which makes it difficult to completely separate and remove the solvent. Become. Moreover, in the manufacturing method of this invention, it is more suitable to react on normal temperature conditions, ie, temperature conditions of 5-35 degreeC. Here, when the reaction is performed at room temperature, it is preferable to use any one of ethylene glycol, propylene glycol, and butylene glycol as the polyhydric alcohol. When other polyhydric alcohols such as glycerin are used, a reaction product may not be produced under normal temperature conditions.

  In the production of the water-soluble silicate monomer, a solvent may not be used during the reaction, but various solvents may be used as necessary. The solvent used in the reaction is not particularly limited, and examples thereof include aromatic hydrocarbons such as benzene, toluene and xylene, esters such as ethyl acetate, methyl acetate, acetone, methyl ethyl ketone, cellosolve, diethyl ether and dioxane, ethers, and the like. , Ketone solvents, polar solvents such as acetonitrile, dimethylformamide and dimethyl sulfoxide, and halogen solvents such as chloroform and dichloromethane. Here, in order to suppress the hydrolysis and condensation reaction of the tetraalkoxysilane used as a raw material, the solvent is preferably dehydrated in advance. Among these, it is preferable to use acetonitrile, toluene, or the like that can accelerate the reaction by forming an azeotrope with an alcohol such as ethanol that is by-produced during the reaction and removing it from the system.

  The mesoporous silica according to the present invention is derived from the components (A) and (B). Hereinafter, the method for producing mesoporous silica according to the present invention will be described.

  In the present invention, first, a mesoporous silica composite is produced using the components (A) and (B). As a method for producing a mesoporous silica composite, a method of mixing ordinary components (A) and (B) in a solvent can be used. In this method, a mesoporous silica composite is usually produced by mixing the component (A) in a solvent and mixing the component (B), and then standing or stirring at a predetermined temperature for a predetermined time.

  As the solvent used for the production of the mesoporous silica composite, usually, water or a solvent containing a mixture of an organic solvent compatible with this and water can be used, and the nonionic surfactant of component (A) From the viewpoint of promoting the formation of self-organization, preferably water alone or a mixed solvent with various alcohols for improving the solubility of the nonionic surfactant, more preferably water alone, water-ethanol or water- It is a mixed solvent of methanol.

  Although the temperature conditions for producing the mesoporous silica composite are not particularly limited, it is usually carried out in the range of room temperature to the boiling temperature of the solvent used. From the viewpoint of mixing and promoting the reaction, the component (A ) Nonionic surfactant is produced in a temperature range in which an aggregate is stably formed. When the nonionic surfactant (A) to be used exhibits a cloud temperature that is the kraft temperature corresponding to the melting point of the hydrate or the solubilization limit temperature of the nonionic surfactant micelle, the cloud point is higher than the kraft temperature. The following temperatures are preferred.

  The reaction time in the production of the mesoporous silica composite is usually in the range of 1 minute to 168 hours, and preferably 5 minutes to 48 hours, more preferably from the viewpoint of hydrolysis and condensation polymerization of the silicate monomer. 30 minutes to 10 hours.

  The production of the mesoporous silica composite in the present invention is carried out under neutral conditions, specifically within the range of pH 4 to 10, particularly preferably pH 6 to 8. Further, from the viewpoint of promoting the progress of hydrolysis and condensation polymerization of the silicate monomer without forming an electrolyte as a by-product, the components (A) and (B) are dissolved in water or a water-alcohol mixed solvent. In addition, for the purpose of accelerating the reaction between the components (A) and (B), it is possible to add an acid or a base as in the production of mesoporous silica by a normal template method. Depending on the intended use of the mesoporous silica, it is necessary to remove the electrolyte by washing.

  In the production of the mesoporous silica composite in the present invention, the nonionic surfactant of component (A) may be used alone or in combination of two or more, and the concentration is particularly limited as long as a three-dimensional micelle structure is formed. Although it is not a thing, the density | concentration in a solution is 0.01 to 80 weight% normally, Preferably it is 0.2 to 30 weight%, More preferably, it is 1.0 to 20.0 weight%.

  In the production of the mesoporous silica composite in the present invention, the ratio of the component (B) to the total of the components (A) and (B) of the water-soluble silicate monomer is usually 0.1 to 98 mol%, preferably 1 to 95 mol%. More preferably, it is 10 to 90 mol%.

  The production confirmation of the mesoporous silica composite produced as described above can be performed by observation with a scanning or transmission electron microscope, powder X-ray diffraction, or the like. The mesoporous silica composite obtained as described above is washed with an acidic aqueous solution, water, an organic solvent compatible with water or an aqueous solution thereof to form a mesoporous silica outer shell, or calcined to obtain mesoporous silica. In addition, it is expected to be used for cosmetic ingredients, paints, building materials and other various composite materials as moisture and solvent holders. It is also expected to be used for films and thin films.

  By further washing the mesoporous silica composite obtained as described above with an acidic aqueous solution, water, an organic solvent compatible with water or an aqueous solution thereof, a mesoporous silica outer shell can be produced.

  The processing solvent used in the production of the mesoporous silica outer shell is not particularly limited, and various solvents can be used. From the viewpoint of maintaining the structure of the mesoporous silica outer shell, it is preferably a polar solvent. More preferably, it is water or alcohol.

  The processing temperature in the production of the mesoporous silica shell is usually performed in the range of room temperature to the boiling temperature of the solvent used, but the structure retention of the mesoporous silica shell, the yield of the mesoporous silica shell, and the boiling point of the processing solvent. In view of the above, it is preferably room temperature to 100 ° C, more preferably room temperature to 80 ° C.

  The treatment time for producing the mesoporous silica outer shell is usually in the range of 1 to 72 hours. From the viewpoint of maintaining the structure of the mesoporous silica outer shell and the yield of the mesoporous silica outer shell, it is preferably 8 to 48 hours. Yes, more preferably 24 to 48 hours.

  An acid aqueous solution may be used in the production of the mesoporous silica shell. It does not specifically limit as an acid, The various acids which exist normally can be used. For example, hydrochloric acid, acetic acid, nitric acid, sulfuric acid, oxalic acid and phosphoric acid. From the viewpoint of the yield of mesoporous silica outer shell, preferred are hydrochloric acid, acetic acid, nitric acid and sulfuric acid, and more preferred are hydrochloric acid and acetic acid.

  Confirmation of the mesoporous silica outer shell produced as described above can be performed by powder X-ray diffraction, nitrogen adsorption / desorption measurement, electron microscope observation, and the like. The mesoporous silica shell obtained as described above is a material for adsorbing and separating specific molecules from a mixture by utilizing the interaction with the mesoporous space obtained using the self-organized structure of the nonionic surfactant as a template. Alternatively, it is expected to be used as a complex that adsorbs a specific substance. In addition, it is also expected to change the form to a film or thin film.

  The mesoporous silica according to the present invention can be produced by firing the mesoporous silica composite or mesoporous silica outer shell obtained as described above.

  The calcination temperature in the production of mesoporous silica is usually in the range of 300 to 900 ° C., preferably 400 to 650 ° C., more preferably from the viewpoint of maintaining the structure of the mesoporous silica and completely removing the surfactant. Is 500-600 ° C

  The calcination time in the production of mesoporous silica is usually performed in the range of 2 to 24 hours, but is preferably 4 to 12 hours, more preferably 6 to 10 hours, from the viewpoint of complete removal of the surfactant. is there.

  The mesoporous silica produced as described above can be used as a catalyst, an adsorbent, and the like in the same manner as obtained by a conventionally known production method. When used as a catalyst, an adsorbent or the like, the mesoporous silica composite, mesoporous silica outer shell, and mesoporous silica of the present invention may be used in combination of these two types or three types, as long as there is no problem. it can.

  Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these examples.

First, a method for producing the water-soluble silicate monomer used in the present invention will be described.
Synthesis example 1
20.8 g (0.1 mol) of tetraethoxysilane and 24.9 g (0.4 mol) of ethylene glycol were added to 150 ml of acetonitrile, and a strongly acidic ion exchange resin (DowEX 50W-X8: Dow) was used as a solid catalyst. (Chemical Co., Ltd.) After adding 1.8 g, the mixture was stirred at room temperature. Initially, the reaction solution separated into two layers was uniformly dissolved after about one hour. Then, after stirring for 5 days, the solid catalyst was separated by filtration, and acetonitrile was distilled off under reduced pressure to obtain 39 g of a transparent viscous liquid. As a result of NMR analysis, it was confirmed that the product was the target (tetra (2-hydroxyethoxy) silane) (yield: 72.5%).

Production of mesoporous silica The present inventors prepared a water-soluble silicate monomer according to the above synthesis example, and tried to prepare mesoporous silica using a nonionic surfactant and the water-soluble silicate monomer.
Example 1
Surfactant POE (20 mol) oleyl ether (0.4 g) was added to ion-exchanged water (3.6 g) and stirred until a homogeneous solution was added, and then tetra (hydroxyethoxy) silane (1.0 g) was added. The mixture was further stirred for 1 hour. The solution had a clear and uniform appearance. When the solution was allowed to stand at 25 ° C. for 8 hours, a thin turbidity was generated in the entire aqueous solution, and when the solution was further allowed to stand for 16 hours, the whole became cloudy and gelled. The gel was freeze-dried to remove water, ethanol was added, and the mixture was allowed to stand at 37 ° C. overnight to remove the ethanol solution containing the surfactant. The remaining white powder was dried by an evaporator to obtain silica powder.

  The silica powder obtained in Example 1 was observed with a transmission electron microscope. A photograph is shown in FIG. From FIG. 1, it was confirmed that a wavy pattern was observed in the center and pores of 10 to 20 nm were present.

Comparative Example 1
Surfactant POE (20 mol) oleyl ether (0.4 g) was added to ion-exchanged water (3.6 g), tetraethoxysilane (1.0 g) was added and stirred. Immediately after stirring, the mixture had the appearance of separating into a cloudy oil phase and a clear aqueous phase. When this mixture was allowed to stand at 25 ° C. for 24 hours, the oil phase gelled while being cloudy. This gel part was freeze-dried to remove water, ethanol was added, and the mixture was allowed to stand at 37 ° C. overnight to remove the ethanol solution containing the surfactant. The remaining white powder was dried by an evaporator to obtain silica powder.

  When the silica powder obtained in Comparative Example 1 was observed with an electron microscope, it was confirmed to be an amorphous silica powder.

  Various types of nonionic surfactants to be used were changed, and an attempt was made to prepare mesoporous silica by the same procedure as in Example 1. The results are shown in Table 1 below (the numbers in the table represent the blending amount (unit: g)). Moreover, the result using the tetraethoxysilane conventionally used widely as a silicate monomer is shown collectively as a comparative example.

When water-soluble tetra (hydroxyethoxy) silane is used as the silicate monomer (Examples 2 to 4), when mixed with various surfactant aqueous solutions, it quickly becomes transparent and uniform, and after at least 24 hours, it is due to silica formation. Gelation of the entire system or sedimentation of silica powder was observed. The obtained silica was found to have a mesoporous structure by electron microscope observation.
On the other hand, when tetraethoxysilane was used as the silicate monomer, the silica formation was very slow because it was not mixed uniformly with the aqueous solution. In Comparative Examples 2 and 4, no silica formation occurred, and Even in the case of Comparative Example 3 where silica formation occurred, only silica formation occurred partially. In order to obtain mesoporous silica using a silicate monomer that cannot be uniformly mixed with an aqueous solution, a known method of adding a lower alcohol as a solubilizer after making the aqueous solution acidic or basic is not adopted. must not.

  Subsequently, various concentrations of the nonionic surfactant were changed, and preparation of mesoporous silica was attempted by the same procedure as in Example 1. The results are shown in the following Table 2 (numbers in the table represent blending amounts (unit: g)). Moreover, the result using tetraethoxysilane is shown collectively as a comparative example.

  In Examples 6 to 8 using a water-soluble silicate monomer, formation of silica or clear gelation of the solution due to formation of silica occurred within 24 hours. In Examples 6 to 8, the surfactant aqueous solution had a micelle phase, a cubic phase, and a hexagonal phase, respectively, but in any phase state, it was compatible with the silicate monomer, and silica was rapidly generated. On the other hand, in the case of Comparative Examples 5 to 7 using a silicate monomer that is insoluble in water, the silicate monomer and the aqueous surfactant solution hardly dissolve, and no silica formation is observed even after one week has passed after mixing. It was.

Example 9
Surfactant POE (10 mol) phytosterol ether (0.8 g) was added to ion-exchanged water (3.2 g) and stirred until uniform. This surfactant solution was confirmed to be a nematic chiral liquid crystal phase by microscopic observation or the like. Tetra (hydroxyethoxy) silane (1.0 g) was added to the liquid crystal and stirred for 10 minutes. The solution had a clear and uniform appearance. When the solution was allowed to stand at 25 ° C. for 3 hours, the entire solution became cloudy. When the solution was further allowed to stand for 17 hours, the entire solution turned white and became gelled. The gel was freeze-dried to remove water, ethanol was added, and the mixture was allowed to stand at 37 ° C. overnight to remove the ethanol solution containing the surfactant. The remaining white powder was dried by an evaporator to obtain silica powder.

  When the silica powder obtained in Example 9 was observed with a transmission electron microscope, regular wavy pores of 10 to 20 nm were confirmed.

Example 10
Ion exchanged water (270 g) and surfactant POE (10 mol) cholesterol ether (15 g) were mixed and stirred until uniform. When tetra (hydroxyethoxy) silane (15 g) was added to this solution and allowed to stand at 60 ° C. for 24 hours, silica was produced from the solution and precipitated. The silica obtained by filtration was allowed to stand at 90 ° C. for 24 hours and dried, and then ethanol was added and stirred overnight at room temperature. After removing the ethanol solution containing the surfactant, the mixture was allowed to stand at 80 ° C. for 5 hours, and the ethanol was removed to obtain silica powder (3.0 g).

  The silica powder obtained in Example 10 was observed with a transmission electron microscope. A photograph is shown in FIG. As shown in FIG. 2, a regular linear and plate-like sheet was obtained in Example 10.

It is the photograph which image | photographed the mesoporous silica powder of Example 1 concerning this invention using the transmission electron microscope. It is the photograph which image | photographed the mesoporous silica powder of Example 10 concerning this invention using the transmission electron microscope.

Claims (8)

Mesoporous silica derived from the following components (A) and (B):
(A) Nonionic surfactant (B) Water-soluble silicate monomer represented by the following general formula (1) Si- (OR ¹ ) ₄ (1)
(In the formula, R ¹ is a polyhydric alcohol residue.) In the mesoporous silica as claimed in claim ^1, (B) R 1 is an ethylene glycol residue of the water-soluble silicate monomers, propylene glycol residue, a butylene glycol residue, glycerol residue or ethylene glycol, propylene glycol, butylene glycol, Mesoporous silica, which is one of the residues of a glycerin condensate.   A mesoporous silica composite which is derived from the components (A) and (B).   A mesoporous silica outer shell derived from the above components (A) and (B).   A method for producing a mesoporous silica composite, wherein the components (A) and (B) are mixed in water or a mixed solvent of water and an organic solvent compatible therewith under neutral conditions. . The method of manufacturing a mesoporous silica composite according to claim 5, (B) R ¹ is an ethylene glycol residue of the water-soluble silicate monomers, propylene glycol residue, a butylene glycol residue, glycerol residue or ethylene glycol, propylene A method for producing a mesoporous silica composite, which is a residue of a condensate of glycol, butylene glycol, or glycerin.   The mesoporous silica composite obtained by the production method according to claim 5 is washed with an acidic aqueous solution, water, an organic solvent compatible with water or an aqueous solution thereof, and the nonionic surfactant of component (A) is removed. A method for producing a mesoporous silica outer shell. A method for producing mesoporous silica, comprising firing a mesoporous silica composite obtained by the production method according to claim 5 or a mesoporous silica outer shell obtained by the production method according to claim 7.