JPH11157827A - New silicon dioxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon dioxide having excellent performance as an adsorbent, filler or the like. SOLUTION: In the distribution curve of pores of the silicon dioxide, the max. value of ΔVp/ΔRp (wherein Vp is the pore volume and Rp is the pore radius) is present in the region of <10 nm pore radius, the max. ΔVp/ΔRp is >=100 mm<3> /nmg, and the proportion of the pore volume corresponding to the range of the peak radius (the pore radius at the max. ΔVp/ΔRp)±1 nm is >=20% of the whole pore volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for selectively adsorbing and holding components when used as an adsorbent for food, a filler for chromatography, a catalyst carrier or a filler for paper. It relates to a novel silicon dioxide that adsorbs and retains.

[0002]

2. Description of the Related Art
Silicon dioxide is widely used in applications such as a desiccant, an adsorption / purification agent, a filler for chromatography, a catalyst carrier, and a filler for paper because of its specific surface area and pore volume. The pore structure of silicon dioxide is determined by the size and degree of aggregation of the primary particles, and silicon dioxide having a pore structure suitable for each application is used. As the technology relating to the above-mentioned applications, for example, regeneration of edible oil, remover of turbid components such as beer, wine, sake, and the like as an adsorption refining agent, and filler for inkjet recording paper as a filler for special paper are known. .

In the technology relating to the above-mentioned applications, the specific surface area, the pore volume, and the average pore diameter are mainly defined as physical properties related to the pore structure of silicon dioxide.

[0004] For example, as an adsorption purifying agent for beer,
In JP-A-5-177132, the particle size is 5 to 1;
A flaky, scaly, or rod-shaped silicon dioxide having a diameter of 00 µm, a pore volume of 0.2 to 1.5 ml / g, and a specific surface area of 100 to 1000 m ² / g is described. Further, as a regenerating agent for edible oil, for example, JP-A-62-100597 discloses a method for regenerating degraded edible oil having a specific surface area of 30.
0-800 m ² / g, pore volume 0.3-2.0 ml /
g, a method of contact-treating silica gel having an average pore diameter of 20 to 150 °. As described above, in many applications, the specific surface area, the pore volume, and the average pore diameter are often specified.

[0005] However, the shape of the pore distribution is not clear from the average pore diameter, and as a result, even if the physical property values are in the above-mentioned range, some of them do not sufficiently exhibit their performance.

On the other hand, as a technique relating to the sharpness of the pore distribution of silicon dioxide, Japanese Patent Application Laid-Open No. 9-143461 discloses the use of a silicon dioxide porous body as a heat storage agent. Describes that the central pore diameter showing the maximum peak in the pore distribution curve is in the range of 1 to 10 nm, and 60 to 100% of the pore volume of the porous body is in the range of the central pore diameter ± 40%. Have been. However, this technique does not describe the range of the pore volume.

Japanese Patent Application Laid-Open No. 9-30809 discloses that
It describes a method for producing silica gel in which the BET specific surface area, pore volume and average pore diameter are controlled to be changed in desired ranges, and a production method capable of obtaining silica gel having a sharp pore distribution. Furthermore, it is described that silica gel having a B / A of 0.6 or less, preferably less than 0.5 is obtained when the median diameter of the peak in the pore diameter distribution is A and the half width is B. Possible specific surface area, pore volume,
The range of the median diameter is not specified.

An object of the present invention is to provide silicon dioxide having excellent adsorption performance over the above-mentioned conventional silicon dioxide, and having high properties as an adsorbent and a filler.

[0009]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that in the reaction between an aqueous solution of an alkali metal silicate and a mineral acid, an alkali metal is produced. The concentration of silicic acid in the aqueous silicate solution is 1
In a pore distribution curve, the silicon dioxide obtained under certain conditions of 0% weight / volume (w / v)% or less has a ΔVp / ΔRp value at a pore radius of 10 nm or less (where Vp is the pore volume and Rp is (Pore radius) and its ΔVp
/ ΔRp value is 100 mm ³ / nm · g or more, and the pore peak radius (ΔVp /
The ratio of the pore volume corresponding to ± 1 nm (pore radius at which ΔRp shows the maximum value) is 20% or more, and the silicon dioxide exhibiting this property exhibits excellent performance when used as an adsorbent or a filler. Was found.

That is, the silicon dioxide according to the present invention has a specific surface area of 300 to 500 m ² / g and a pore volume of 0.8 to 500 m ² / g.
Although it is silicon dioxide having a general physical property value of 1.4 ml / g, a pore radius of 1
Having a maximum value of ΔVp / ΔRp in a region of 0 nm or less,
The maximum value ΔVp / ΔRp is 100 mm ³ / nm ·
g or more, and the ratio of the pore volume corresponding to the pore peak radius ± 1 nm to the total pore volume is 20% or more. This feature shows that the pore distribution is sharp, and shows excellent performance when used as an adsorbent and a filler.

Hereinafter, the present invention will be described in more detail. Silicon dioxide of the present invention, in the pore distribution curve,
The maximum value of the ΔVp / ΔRp value is within a range of a pore radius of 10 nm or less, and the maximum value ΔVp / ΔRp value is 100 mm.
³ / nm · g or more, and the ratio of the pore volume corresponding to the pore peak radius ± 1 nm to the total pore volume is 20%.
A silicon dioxide having the characteristics described above.

Here, it is important for achieving the object of the present invention that the maximum value of the ΔVp / ΔRp value be within a pore radius of 10 nm or less. Where ΔVp / Δ exceeds 10 nm
When there is a maximum value of the Rp value, the performance particularly when used as an adsorbent for a polymer substance such as a protein is reduced. More preferably, the maximum value of the ΔVp / ΔRp value is in the range of 3 to 8 nm, more preferably, in the range of 3 to 5 nm. in this case,
It is desirable that the maximum value of ΔVp / ΔRp be over 3 nm.

Next, the silicon dioxide of the present invention has a maximum value ΔVp / ΔRp of 100 mm ³ / nm · g or more. If it is less than 100 mm ³ / nm · g, the pore volume in this pore radius range will be small, sharpness will be impaired, and the selectivity of adsorption will decrease, or the amount of adsorption will decrease even if the selectivity is maintained. . More preferably, the maximum value ΔVp /
The ΔRp value is 200 mm ³ / nm · g or more, more preferably 400 mm ³ / nm · g or more.

Further, in the silicon dioxide of the present invention, the ratio of the pore volume corresponding to the pore peak radius ± 1 nm to the total pore volume is at least 20%, more preferably at least 40%. If it is less than 20%, the sharpness of the pore distribution is impaired, and the selectivity of adsorption is reduced.

The silicon dioxide of the present invention preferably has a specific surface area of 300 to 500 m ² / g and a pore volume of 0.8 to 1.4 ml / g by a nitrogen adsorption method by a BET method. In general, as the specific surface area of silicon dioxide decreases, the pore diameter and the pore volume increase, and the pore distribution tends to be broad. Also, as the specific surface area increases, the pore volume tends to decrease and the pore distribution tends to be sharp. Therefore, if it is less than 300 m ² / g, the sharpness of the pore distribution may be impaired,
If it exceeds 0 m ² / g, the pore distribution becomes sharper, but the pore volume becomes smaller, and the amount of adsorption may decrease.

The average particle diameter of the silicon dioxide of the present invention is preferably 1 to 30 μm, more preferably 5 to 20 μm. When the average particle size is less than 1 μm,
When used as an adsorbent, it may be difficult to remove silicon dioxide itself, and when it exceeds 30 μm, adsorption performance may be reduced.

Further, the silicon dioxide of the present invention has an oil absorption of 1
It is preferably at least 50 ml / 100 g. When used as a filler for paper, the oil absorption is necessary to retain water and water-soluble polymer as a medium, and 150 ml / 100 g
If it is less than 1, sufficient performance may not be expected.

Further, the pH of the 5% by weight slurry of the silicon dioxide of the present invention is preferably 8 or less, particularly preferably 4 to 8. If the pH is higher than 8, the specific surface area may decrease and the pore peak radius may increase due to aging.

The silicon dioxide according to the present invention can be obtained by a method according to a so-called wet process silica production method by a neutralization reaction between an aqueous solution of an alkali metal silicate and a mineral acid. In this case, the silicic acid concentration in the alkali metal silicate aqueous solution is 10 w / v% or less, more preferably 2 to 8 w / v.
It is recommended to run the reaction as v%.

As the alkali metal silicate, it is preferable to use sodium silicate No. 3 from an economic viewpoint. Also, as the mineral acid, sulfuric acid and hydrochloric acid are preferable from the same economic point of view. The concentration of the mineral acid is preferably 6 to 16N.

The alkali metal silicate aqueous solution is heated, and sulfuric acid of a predetermined concentration is added. The temperature at the time of addition is 50 ~
100 ° C. is preferred. If necessary, sulfuric acid may be added in several portions. The final neutralization ratio is preferably 80 to 95%. If necessary, after completion of the addition of sulfuric acid, the mixture can be heated to 80 ° C. or higher. After the completion of the reaction, the pH is 5.5 or less,
In particular, it is preferable to reduce it to 3 to 5.

It is preferable that the obtained silicon dioxide slurry is filtered, washed, redispersed in water, and readjusted to a pH of 5.5 or less, particularly 3 to 5. afterwards,
Filtration, washing, drying to obtain silicon dioxide, further pulverized,
By classification, silicon dioxide having a predetermined particle size can be obtained.

The silicon dioxide of the present invention can be used for applications where silicon dioxide is conventionally used, and is particularly suitable as an adsorbent, a catalyst carrier and a filler. The adsorbent can be used as a refining agent for edible oils, beer, wine and the like, and is also effective as a filler for chromatography, a filler for paper, and the like. In this case, the silicon dioxide of the present invention has a specific adsorption performance for a substance having a molecular weight of about 25,000 to 50,000, particularly for a protein.

[0024]

The silicon dioxide of the present invention has excellent performance as an adsorbent, a filler and the like.

[0025]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, the methods for measuring the physical properties of silicon dioxide and the methods for measuring the adsorption characteristics for proteins are as follows.

Measurement of Physical Properties of Silicon Dioxide [Average Particle Size] The particle size distribution was measured using a 100 μm aperture with a Coulter Counter TA-II type particle size analyzer manufactured by Coulter Co., Ltd.
% Diameter) was taken as the average particle diameter. [Product pH] A 5 g sample was dispersed in 100 ml of ion-exchanged water, and after boiling once, cooled to room temperature, and the pH of the slurry was measured. [Specific surface area] It was measured by a nitrogen adsorption method (BET method) using a fully automatic specific surface area / pore distribution measuring device (BELSORP28) manufactured by Bell Japan. The sample was pretreated at 160 ° C. for 2 hours under vacuum. (Reference: SB
runauer, P .; H. Emmett, E .; Tell
er, J. et al. Amer. Chem. Soc. , 60 , 30
9 (1938)) [Pore volume] A nitrogen adsorption isotherm was determined using the above-mentioned BELSORP28, and a pore radius of 1 to 100 nm was obtained by a Drillmore-Heel analysis method in accordance with JIS-K1150.
Was determined. This value was taken as the total pore volume. The pore volume in the range of the pore peak radius ± 1 nm was determined from a curve plotting the integral value with respect to the pore radius by the same method. [Pore distribution] The pore distribution was measured by the nitrogen adsorption method using BELSORP28 described above. The calculation of the pore distribution is
The method of Dolimore Heal (D. Dolimore,
G. FIG. R. Heal, J.M. Appl. Chem. , 14 ,
109 (1964)). The sample was pretreated at 160 ° C. for 2 hours under vacuum. [Pore peak radius] It was determined from the pore distribution diagram of each sample shown in FIG. This is the pore radius indicating the maximum value of ΔVp / ΔRp. [Average pore radius] Average pore radius (nm) = 2000 × (pore volume (ml / g) / specific surface area (m ²
/ G)). [Oil absorption] Measured according to the method of JIS-K-5101. [Protein adsorption property] The protein was dissolved in a 10 v / v% ethanol aqueous solution to prepare a 100 ppm protein solution. 500 ppm of silicon dioxide was added to this solution, and 20
Stirred for minutes. After filtration, the absorbance at 280 nm was measured. The proteins used were trypsin inhibitor (molecular weight 20100), carbonic anhydrase (molecular weight 30000), bovine serum albumin (molecular weight 6900)
0), catalase (molecular weight 230,000). The adsorption rate was calculated from the following equation. Adsorption rate = 100 − [(absorbance of silicon dioxide treatment liquid) /
(Absorbance of Untreated Silicon Dioxide)] × 100 FIG. 2 shows the results of each sample.

[Example 1] 75 L of an aqueous solution of sodium silicate No. 3 having a silicic acid concentration of 6 w / v% was heated to 60 ° C, and 2.4 L of 12 N sulfuric acid was added with stirring.
Next, stir for 30 minutes and add 0.70 L
Was added. Heat at 60 ° C. for another 10 minutes. Next, 0.53 L of 12N sulfuric acid was added, and the temperature was further increased to 60 ° C for 30 minutes.
And heated. After adjusting the pH to 4.0, the slurry was filtered, washed and redispersed in water. After re-adjusting the pH to 4.0, the mixture was filtered, washed, dried, pulverized, and classified to obtain silica having a predetermined particle size. Table 1 shows the physical property values and protein adsorption characteristics of the obtained silica.

Example 2 75 L of an aqueous solution of sodium silicate No. 3 having a silicic acid concentration of 5 w / v% was heated to 70 ° C., and 2.0 L of sulfuric acid having a 12N concentration was added with stirring.
Next, the mixture was stirred for 30 minutes, and 1.0 L of 12N sulfuric acid was added. Heat for an additional 30 minutes. After adjusting the pH to 4.0, the slurry was filtered, washed and redispersed in water. pH
Was readjusted to 4.0, filtered, washed, dried, pulverized and classified to obtain silica having a predetermined particle size. Table 1 shows the physical property values and protein adsorption characteristics of the obtained silica.

Comparative Example 1 50 L of an aqueous solution of sodium silicate No. 3 having a silicic acid concentration of 11 w / v% was heated to 60 ° C., and 2.1 L of sulfuric acid having a 12N concentration was poured under stirring.
After further stirring for 30 minutes, the temperature was raised to 90 ° C. Again 12
2.3 L of sulfuric acid at a specified concentration was added. After the addition was completed, the mixture was further stirred at 95 ° C. for 30 minutes. After adjusting the pH to 4.0, the mixture was filtered, washed, and redispersed in water. After the pH was readjusted to 4.0, silica having a predetermined particle size was obtained by further drying, pulverizing, and classifying. Table 1 shows the physical property values and protein adsorption characteristics of the obtained silica.

Comparative Example 2 After adding 2.5 kg of sodium sulfate to 50 L of an aqueous solution of sodium silicate No. 3 having a silicic acid concentration of 7 w / v%, the mixture was heated to 40 ° C., and stirred.
0.8 L of sulfuric acid having a 2N concentration was added. After further stirring for 30 minutes, 1.6 L of 12N sulfuric acid was again added. After the addition was completed, the mixture was filtered, washed, and redispersed in water. pH
Was readjusted to 4.0, and further dried, pulverized and classified to obtain silica having a predetermined particle size. Table 1 shows the physical property values and protein adsorption characteristics of the obtained silica.

COMPARATIVE EXAMPLE 3 20 L of an aqueous solution of sodium silicate No. 3 having a silicic acid concentration of 19 w / v% and 3.3 L of sulfuric acid having a 12N concentration were added to water 5 which had been heated to 60 ° C. in advance.
While stirring to 0 L, it was added simultaneously over 30 minutes.
The pH during the addition was 4-6. After the addition was completed, the pH of the slurry was adjusted to 4, and the temperature was adjusted to 200 ° C.
Heated for 0 minutes. After cooling, the mixture was filtered, washed, and redispersed in water. After the pH was readjusted to 4.0, silica having a predetermined particle size was obtained by further drying, pulverizing, and classifying. Table 1 shows the physical property values and protein adsorption characteristics of the obtained silica.

[0032]

[Table 1]

As can be seen from the above results, in particular, from the results shown in FIG. 2, it was confirmed that the silicon dioxide of the examples exhibited specific adsorption characteristics for substances (proteins) having a specific molecular weight.

[Brief description of the drawings]

FIG. 1 is a pore distribution diagram of an example and a comparative example.

FIG. 2 is a graph showing the adsorption performance of Examples and Comparative Examples for various proteins.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01J 32/00 B01J 32/00 C12H 1/04 C12H 1/04

Claims (9)

[Claims] In the pore distribution curve, the pore radius is 10n.
m or less, ΔVp / ΔRp value (where Vp is the pore volume, R
p has the maximum value of the pore radius), the maximum value of the ΔVp / ΔRp value is 100 mm ³ / nm · g or more, and the pore peak radius (ΔVp / ΔRp is the maximum value) with respect to the total pore volume. Silicon dioxide having a pore volume ratio corresponding to a range of ± 1 nm of the pore volume, which is 20% or more of the total pore volume. 2. In the pore distribution curve, the pore radius is 3 to 8
In nm, ΔVp / ΔRp value (where Vp is pore volume, Rp
Has the maximum value of the pore radius), the maximum value of the ΔVp / ΔRp value is 200 mm ³ / nm · g or more, and the pore peak radius (ΔVp / ΔRp is the maximum value) with respect to the total pore volume. 2. The silicon dioxide according to claim 1, wherein a ratio of a pore volume corresponding to a range of ± 1 nm is 20% or more of a total pore volume. 3. A pore distribution curve, wherein the pore radius is 3-5.
In nm, ΔVp / ΔRp value (where Vp is pore volume, Rp
Has the maximum value of the pore radius), the maximum value of ΔVp / ΔRp is 400 mm ³ / nm · g or more, and the pore peak radius (ΔVp / ΔRp is the maximum value) with respect to the total pore volume. 3. The silicon dioxide according to claim 2, wherein the ratio of the pore volume corresponding to the range of ± 1 nm of the pore volume is 40% or more of the total pore volume. 4. A specific surface area of 300 to 500 m ² / g,
4. The silicon dioxide according to claim 1, wherein the pore volume is 0.8 to 1.4 ml / g. 5. The method according to claim 1, wherein the average particle size is 1 to 30 μm.
The silicon dioxide according to any one of claims 1 to 4. 6. An average particle size of 5 to 20 μm.
The silicon dioxide as described. 7. The silicon dioxide according to claim 1, wherein the pH of the 5% by weight slurry is 8 or less. 8. The silicon dioxide according to claim 1, which has an oil absorption of 150 ml / 100 g or more. 9. The silicon dioxide according to claim 1, which is obtained by reacting an aqueous solution of an alkali metal silicate having a silicic acid concentration of 10% by weight or less with a mineral acid.