JP2668958B2 - Method for producing spherical silica porous material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a spherical silica porous material.

[Conventional technology]

 Recently, acids containing organic substances represented by alkoxides
Using a sol-gel method as a raw material,
A method for manufacturing a porous body is known (Journal of the Ceramic Industry Association,87
(8) P.434 (1979)).

The sol-gel method can easily form, in addition to pure silica, an oxide composition in which another metal oxide is uniformly mixed with silica in a molecular order. The sol-gel method has been widely studied as a method for producing glass which does not require melting, and as a method for producing ceramic fine powder ("Amorphous Glass Chemistry" by Sao Sakuhana).

On the other hand, a mixed solution of water and ethanol is added to polyethoxysiloxane obtained by partially hydrolyzing (partially condensing) tetraethoxysilane, and the mixture is stirred to form an emulsion, and then a catalyst is added to cause gelation. There is known a method of producing a porous gel by producing a spherical gel, separating the gel from a solution, and drying the gel (see Journal of Chromatography (Journal of Chromatography)).
of Chromatography), 83 (1973) 5-9).

[Problems to be solved by the invention]

However, in the above method, it is difficult to obtain a spherical silica porous material having a large pore size and a sharp pore distribution.

[Means for solving the problem]

That is, the present invention provides the following general formula (I) (In the formula, n represents an integer of 0 to 8, and R represents an alkyl group.) An organic solvent substantially incompatible with water is added to a solution containing a partial condensate of a silicon alkoxide represented by the formula: A fine silica gel is produced by dropping an organic solvent in which the condensate is dissolved into water, and then the gel is separated from the solution, and then calcined at 800 to 1200 ° C. The gist is a method for producing a body.

In the present invention, during the reaction, the alkoxide undergoes a hydrolysis reaction to form an alcohol, and since it is necessary to remove this alcohol to the outside of the reaction system by means such as distillation, the silicon alkoxide used in the present invention is particularly preferred. Although not limited, lower alkoxides of silicon, specifically, tetraethyl silicate, tetramethyl silicate and the like can be mentioned.

Examples of the partial condensate of silicon alkoxide include those in which n in the following general formula (I) is 0 to 8.

General formula (I) (In the formula, n represents an integer of 0 to 8 and R represents an alkyl group.) A differential condensate of silicon alkoxide is produced by hydrolysis of silicon alkoxide.

The molar ratio of water to silicon alkoxide (H ₂ O / Si (OR) ₄ , R: alkyl group) when performing this hydrolysis reaction is as follows:
The range is about 0.1 to 2.0.

When performing this hydrolysis reaction, a solvent is not particularly necessary, but by adding a lower alcohol solvent such as methyl alcohol or ethyl alcohol, the silicon alkoxide can be melted well.

The reaction temperature at the time of performing this hydrolysis reaction may be a temperature from room temperature to about 80 ° C.

In carrying out this hydrolysis reaction, the reaction can be carried out smoothly by adding a catalyst, for example, an inorganic acid such as hydrochloric acid, nitric acid or sulfuric acid or an organic acid such as an organic carboxylic acid to the reaction system.

The hydrolysis reaction can be obtained in a state where the partial condensate of the silicon alkoxide of the present invention is concentrated by removing the solvent added to the reaction system or the generated alcohol by distillation.

An organic solvent is added to a solution containing a partial condensate of a silicon alkoxide obtained by the above hydrolysis reaction to dissolve the condensate.

As the organic solvent used, it is substantially incompatible with water, is compatible with a partial condensate of silicon alkoxide without gelling, and forms a stable emulsion when dropped in water in the next step. There is no particular limitation so long as it is such a hydrocarbon, and specific examples thereof include hydrocarbons such as hexane, cyclohexane and benzene, and alcohols having a relatively large number of carbon atoms such as t-amyl alcohol.

In the present invention, an organic solvent in which a partial condensate of a silicon alkoxide thus obtained is dissolved is dropped into water to carry out a reaction for generating a fine gelled product.

Examples of the catalyst used in this reaction include acid, ammonia, organic hydrochloric acid, alkali and the like.
Preferred catalysts include ammonia. The amount of the catalyst is 0.1 to 1 per mole of silicon atom.
The range is 5 mol, preferably 0.5 to 5 mol.

This reaction is performed by a method generally called a sol-gel method.

Since the organic solvent in which the partial condensate of silicon alkoxide is dissolved exhibits lipophilicity, when the organic solvent is dropped into water, spherical particles are dispersed in water to form a so-called O / W state. In this case, a common surfactant used to form an O / W suspension in water, for example, polyoxyethylene sorbitan monolaurate, etc.
It is preferable to add 5% by weight, preferably 0.1 to 2% by weight.

Water as the dispersion medium may be a mixed solution of water and an alcohol soluble in water, such as methanol and ethanol.

An aqueous solution of 1 to 100 parts, preferably 2 to 50 parts (volume) is used with respect to 1 part of an organic solvent in which a partial condensate of silicon alkoxide is dissolved. The reaction temperature for gelling may be in the range of 5 to 80C. The reaction time may be in the range of 0.5 to 24 hours.

The gel obtained in this manner is then converted from water to
Separation is performed by a commonly used method such as decantation or filtration.

The obtained gel is washed if necessary, and then dried at a temperature from room temperature to about 200 ° C.

The average particle size of the gelled product may be 1 to 500 μm.

In the present invention, it is necessary to calcine the dried product thus obtained at a specific temperature.

Examples of the firing temperature include a range of 800 to 1200 ° C.

The firing time can be in the range of 1 hour to 1 day.

In the present invention, the method of raising the temperature in the firing treatment is not particularly limited.For example, after drying, the firing may be performed while continuously raising the temperature to 800 to 1200 ° C., or 400 to 400 ° C. After firing at a temperature of up to 800 ° C, it may be cooled to room temperature and then fired again at a temperature of 800 to 1200 ° C.

The calcination is performed in a high-temperature oxidizing atmosphere, for example, under a flow of air.

As described above, the spherical silica porous material of the present invention can be manufactured.

The spherical silica porous material produced according to the present invention is used as a separating agent, an adsorbent, a catalyst carrier, a carrier for immobilizing microorganisms, a filler and the like.

According to the present invention, not only a spherical silica porous material having pores with a pore radius of 100 Å or more can be obtained, but also a pore diameter of 100
In the range of up to 1000Å, those having a sharp pore distribution such that the pore distribution has a substantially single peak can be obtained. In conventional silica alkoxide-based spherical silica carriers, gelled silicon alkoxides or dried products are used as they are, or only carriers obtained by hydrogenating this are known. Is not a sharp pore distribution as in the present invention, and also in the present invention, when fired at a temperature of 800 ℃ or less,
Although a product having a sufficient pore volume with a pore radius of 100 mm or more can be obtained, a product having a sharp pore distribution such that the pore distribution is substantially a single peak in the range of the pore size of 100 to 1000 mm is obtained. By firing at a temperature of 800 ° C. to 1200 ° C., the pore distribution becomes substantially single peak in the range of the pore radius 100Å to 1000Å without decreasing the pore volume for the first time. Such a sharp pore distribution is obtained.

〔Example〕

Hereinafter, the content of the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

The pore distribution and amount were measured with a mercury porosimetry porosimeter (Autobore 1200 manufactured by Micrometrics). The measurement range of the pores is in the range of about 20 ° to about 30,000 ° in radius. The specific surface area was calculated by the BET method using a nitrogen adsorption method. The model used for the measurement was Carlo Elba's Soapmatic 18
00.

Comparative Example 1 and Example 1 500 g of tetraethyl orthosilicate (manufactured by Tokyo Kasei)
A solution consisting of 136.3 g of ethanol, 43.24 g of water and 18.7 g of a 0.1N-HCl ethanol solution was added thereto, and heated at 60 ° C. for 30 minutes to prepare a partial hydrolyzate of tetraethyl orthosilicate (H ₂ O / Si (OEt) ₄ molar ratio 1.0, HCl / Si (OE
t) ₄ molar ratio 0.001). Next, the volatile liquid was distilled by first heating at 120 ° C. and then at 150 ° C. under an atmosphere of flowing argon.

45 ml of the solution of the partial condensate of the obtained silicon alkoxide
In addition, 22.5 ml of t-amyl alcohol and cyclohexane 7.
5 ml was added to make a homogeneous solution. This was dropped into an aqueous solution consisting of 433.9 g of water, 13.5 g of ethanol and 3.4 g of Tween 20 (Kanto Chemical Co., Inc., polyoxyethylene sorbitan monolaurate) to form droplets, and then 36 ml of 28% ammonia water and Ammonia solution consisting of 22.5 ml of water was added little by little while continuing to stir to gel. After further stirring for 5 hours, the mixture was allowed to stand overnight to precipitate the product. After removing the supernatant by decantation, add ethanol.
The mixture was stirred for 30 minutes, decanted again, and washed. After separating from the solution by passing through further, it was dried in a dryer at 100 ° C. for 8 hours (yield 13.6 g). This dried product at 2 ℃ / mm
After heating to 600 ° C, holding for 3 hours and firing under air flow, 700
Calcination was performed at 5 ° C. for 5 hours. The total pore volume of this comparative sample is
2.70cc / g (pore volume 1.91cc /
g), the surface area is 328 m ² / g, and its pore distribution curve is
Shown in the figure.

The comparative sample obtained as described above was further baked at 900 ° C. for 5 hours to obtain the porous body of the present invention. The porous body of the present invention has a clean spherical shape with a particle diameter of about 20 μ to 100 μ, and the total pore volume is 2.25 cc / g (pore volume 1.73 cc / g in the range of pore radius 100 ° to 1000 °). ), The surface area was 211 m ² / g. The pore distribution curve is as shown in FIG.
It can be seen that the pore distribution has a substantially single peak in the range of 100 to 1000Å, and that the pore distribution is sharp.

From the above results, the comparative sample fired at 700 ° C has a pore volume of 2.0 cc / g or more with a pore radius of 100 Å or more.
It can be seen that the porous body of the present invention calcined at 0 ° C. has almost no decrease in the pore volume, and the pore distribution is clearly sharper than the comparative sample.

Example 2 A partial condensate of silicon alkoxide was prepared in the same manner as in Example 1. 9.4 ml of cyclohexane was added to 37.5 ml of this solution.
Was added dropwise to an aqueous solution containing 531 ml of water, 60 ml of ethanol and 9.0 g of Tween 20 to form droplets, and then 28%
An ammonia solution consisting of 45 ml of ammonia water and 105 ml of water was added while continuing stirring to cause gelation. This gel was washed, separated, dried and calcined in the same manner as in Example 1. 900
The calcinated product was a fine spherical particle of about 10 to 60 μm, and its pore distribution curve was almost the same as in Example 1.

〔The invention's effect〕

The spherical silica porous body obtained by the production method of the present invention has pores with a uniform pore diameter larger than the conventional one, and is fired at a high temperature. Alternatively, it has the following advantages as compared with the case where it is dried but the pore diameters are not uniform.

First, since it has a larger pore diameter than the silica porous material obtained by the conventional sol-gel method, it can be used, for example, as a separating agent for a large molecular size, particularly, a bio-related substance. Further, when the porous silica obtained in the present invention is used as a raw material for quartz glass, large pores remain even after firing at a high temperature, so that it is easy to reduce silanol groups in the quartz glass.

Second, as compared with a conventional spherical silica carrier using an alkoxide as a raw material, the porous body obtained by the present invention has a higher strength when used as a separating agent or the like because it is calcined at a high temperature. It has advantages such as high temperature, reusability by high temperature treatment, and improved alkali resistance when used in an aqueous solution. Further, since the pore diameters are uniform, it is very effective in separating specific molecules.

Third, when compared with a conventionally known porous body made of silica containing an alkali metal as a raw material, the porous body according to the present invention is substantially composed of only silica. Keeps a large pore volume even after firing. Therefore, it can be used at a higher temperature than the conventional porous body, and can be a silica porous body treated at a high temperature, which increases the alkali resistance when used in an aqueous solution,
Surface silanol groups can be reduced.

[Brief description of the drawings]

1 and 2 are diagrams showing a pore distribution curve of the spherical porous silica obtained in Comparative Example 1 and Example 1, respectively. Curve 1 is a curve showing the state of pore distribution, and curve 2 is Is the integral curve of pore volume.

Claims (1)

(57) [Claims] 1. A compound represented by the following general formula (I) (In the formula, n represents an integer of 0 to 8, and R represents an alkyl group.) An organic solvent substantially incompatible with water is added to a solution containing a partial condensate of a silicon alkoxide represented by the formula: A fine silica gel is produced by dropping an organic solvent in which the condensate is dissolved into water, and then the gel is separated from the solution, and then calcined at 800 to 1200 ° C. How to make the body.