JPH1135315A - Production of high density mesoporous body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high density mesoporous body having a uniform pore diameter which is useful as an adsorbent and the like with good reproducibility while suppressing the reaction by mixing an alkoxysilane having a specified acid value, water and a surfactant. SOLUTION: An alkoxy silane having <=0.0045 acid value, preferably tetramethoxysilane, and water and a surfactant preferably comprising a compd. having 2 to 18C alkyl groups and hydrophilic groups and more preferably alkyltrimethylammonium (e.g. hexadecyl trimethylammonium chloride) are mixed while adding a small amt. of an acid (diluted hydrochloric acid) to control pH to 1 to 4. Then an aq. soln. of NaOH is added to the mixture to control the pH to >=5 and to form a gel. The powdery or film state silica/surfactant composite body thus obtd. is subjected to calcination at 400 to 1000 deg.C or to solvent treatment with alcohol to remove the surfactant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an adsorbent which can be used for recovery of a solvent or gasoline, an adsorption heat pump, temperature control, water treatment, deodorization, etc., purification of exhaust gas, organic synthesis, petroleum reforming and cracking, etc. TECHNICAL FIELD The present invention relates to a method for producing a high-density mesoporous material that can be used as a catalyst or the like that can be used in a process.

[0002]

2. Description of the Related Art Among porous bodies, a pore diameter (in this specification, the diameter of pores of the porous body) is particularly 1 to 10 n.
The porous body in the range of m and the pore diameter is distributed in a particularly narrow range is called a mesoporous body. Among these mesoporous materials, those having a bulk density of 0.5 g / cc or more are particularly called high-density mesoporous materials.

As a method for producing this high-density mesoporous material, first, a method of mixing an alkoxysilane, water and a surfactant to form a silica / surfactant composite, and then removing the surfactant. (Japanese Patent Application No. 8-69072). Secondly, as a method for producing a film-like high-density mesoporous material, a method in which an alkoxysilane is hydrolyzed under acidic conditions, and a solution in which a surfactant is further mixed is applied to a substrate and dried. (Japanese Patent Application No. 7-101329).

[0004]

However, the above conventional manufacturing method has the following problems. In the first method, the solution containing silica / surfactant gelled spontaneously within 1 to 6 hours, the gelation time was not constant, and it was difficult to control the reaction. In addition, if the degree of polymerization of the alkoxysilane before the reaction is different, the time until finally gelation is not constant, and it is difficult to repeatedly obtain a mesoporous material having the same characteristics, resulting in poor reproducibility. Low.

In the case where the ratio of the hydrolyzate (Si (OX) _4-n (OH) _n ) (X = alkyl group, n: natural number) in the raw material alkoxysilane is large, silica / The time required for the solution of the surfactant complex to gel becomes shorter. If this time is too short, uniform pores may not be sufficiently developed. The second method is a method for forming a porous film, and does not disclose a method for forming a three-dimensional porous body.

The present invention has been made in view of the above problems, and has as its object to provide a method for producing a high-density mesoporous material having a uniform pore diameter and excellent reproducibility.

[0007]

According to the first aspect of the present invention, there is provided a method for producing a high-density mesoporous material obtained by mixing an alkoxysilane, water and a surfactant, gelling the mixture, and then removing the surfactant. The above alkoxysilane is a method for producing a high-density mesoporous material, wherein the acid value is 0.0045 or less.

According to the present invention, the acid value of alkoxysilane is set at 0.1.
By lowering it to 0045 or less, a sufficient time from the state of the silica / surfactant solution to the gelation is sufficiently ensured, and a high-density mesoporous material having a uniform pore diameter is obtained. That is, since the silica / surfactant does not gel even when left to stand, the pores can be formed in a sufficient time, and a high-density mesoporous material having uniform pore characteristics can be obtained. On the other hand, if the acid value of the alkoxysilane exceeds 0.0045, the time required for the solution of the silica / surfactant complex to gel becomes short, and uniform pores may not be sufficiently developed. Also, it is difficult to control the gelling reaction and the pore characteristics.

Alkoxysilanes are, for example, of the formula Si
(OX) ₄ (X = alkyl group). Alkoxysilane undergoes hydrolysis by mixing with water or the like, and changes to (Si (OX) _4-n (OH) _n ) (X = alkyl group, n: natural number). Here, the release of H as H ⁺ causes the alkoxysilane solution to show a slight acidity. The measured value of the acidity of this solution is defined as the acid value of the alkoxysilane. Therefore, by measuring the acidity of the above solution, the amount of hydrolyzed alkoxysilane can be indirectly known.

The method for measuring the acid value of alkoxysilane will be described. 1 g of KOH in 500 ml of ethanol
To prepare a KOH solution. 2 ml from KOH solution
Weigh and transfer to a beaker, add a small amount of phenolphthalein and the solution will turn light purple. A certain amount of alkoxysilane is added thereto, and a point at which the solution turns transparent within 5 minutes is regarded as a neutralization point. The amount of alkoxysilane added before neutralization is measured, and from that value, the weight of KOH required to neutralize 1 g of alkoxysilane is determined, and this is defined as the acid value of the alkoxysilane.

An example of measuring the acid value of alkoxysilane will be described. The acid values of two kinds of tetramethyl orthosilicates as alkoxysilanes were measured by the above-mentioned method using KOH. On the other hand, when up to 75 ml of tetramethylorthosilicate (manufactured by Tokyo Kasei, hereinafter referred to as TMOS-A) is added, the KOH solution exhibits a light pink color.
When added, the KOH solution became clear and neutralized. From the amount of TMOS-A when it became transparent (80 ml),
The weight of KOH required to neutralize 1 g of TMOS-A was 0.0049 mg / g. This is defined as the acid value of TMOS-A.

In addition, in the case of the other tetramethyl orthosilicate (Tama Chemical Co., Ltd., hereinafter referred to as TMOS-B), the KOH solution is pale pink when added up to 130 ml. The KOH solution became clear and neutralized. TMOS when it becomes transparent
From the amount of B (140 ml), the weight of KOH required to neutralize 1 g of TMOS-B was determined.
It was 026 mg / g. This is defined as the acid value of TMOS-B.

The production method of the present invention can form uniform pores according to the following principle. The principle is presumed as follows. The alkoxysilane and the surfactant form a silica / surfactant complex under acidity.
This complex is a solution at the beginning of the reaction, but gels as the reaction proceeds. At this time, gelation occurs in a state in which the molecular aggregate of the surfactant is formed in the network silica skeleton. Therefore, uniform pores corresponding to the size of the molecular assembly of the surfactant are formed in the gel. Thereafter, by removing the surfactant from the gelled silica / surfactant composite, pores corresponding to the size of the molecular assembly of the surfactant are opened in the gel.

Next, the details of the present invention will be described. As the alkoxysilane, one or more kinds of alkylalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and methyltrimethoxysilane can be used. The alkoxysilane is particularly preferably tetramethoxysilane. Thereby, a high-density mesoporous body can be manufactured relatively easily.

The above-mentioned surfactant is preferably a compound having an alkyl group and a hydrophilic group. By using this compound, a molecular assembly of the surfactant is formed in the reaction solution, and 1 to 1 corresponding to the size of the molecular assembly is formed.
The effect that uniform pores of about 10 nm are formed in the high-density mesoporous body can be obtained.

The alkyl group preferably has 2 to 18 carbon atoms. By using a surfactant comprising these alkyl groups, the effect that the above-mentioned molecular assembly is efficiently formed can be obtained.

Incidentally, the surfactant having more than 18 carbon atoms is not commercially available and may be costly. In addition, when the number of carbon atoms is 1, that is, when the alkyl group is a methyl group, the above-mentioned molecular aggregate is difficult to be formed, and uniform pores of about 1 to 10 nm may not be formed. Examples of the hydrophilic group include -N ⁺ (CH ₃ ) ₃ , = N ⁺ (CH ₃ ) ₂ , ≡N
⁺ (CH ₃ ) ≡N ⁺ , -NH ₂ , -NO, -OH, -C
OOH and the like can be mentioned.

As the surfactant, a compound represented by the following chemical formula can be used. As such a compound, alkyltrimethylammonium is preferably used. Alkyltrimethylammonium is represented by the following chemical formula.

Chemical formula: C _n H _{2n + 1} N (CH ₃ ) ₃ X Here, n is an integer of 2 to 18, and X is a halide ion such as a chloride ion or a bromide ion.

By using such a surfactant, a molecular aggregate of the surfactant is efficiently formed in the reaction solution, and uniform pores of about 1 to 10 nm corresponding to the molecular aggregate are formed. The effect of being easily performed can be obtained. The surfactant represented by the above chemical formula is, for example,
Hexadecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, decyltrimethylammonium bromide, octyltrimethylammonium bromide and the like can be mentioned.

The surfactant may be added as a powder, or may be used by dissolving it in a solvent such as water or methanol. The cation concentration of the surfactant is not particularly limited. Further, as the solution in which the surfactant is dissolved in the solvent, either a solution prepared by oneself or a commercially available solution may be used. From a cost standpoint, using a commercially available solution is preferred over preparing it yourself from powder.

The amount of the surfactant added is 1 to 1 mol of Si contained in all the raw materials including the alkoxysilane.
It is preferable to add so that it may become 10 mol. When the addition amount of the surfactant is more than 10 mol, the surplus surfactant which does not contribute to the formation of the silica / surfactant complex is mixed in the silica / surfactant complex, and There is a possibility that the density may decrease or the manufacturing cost may increase.

On the other hand, when the addition amount of the surfactant is less than 1 mol, excess silica not contributing to the formation of the silica / surfactant complex is mixed in the silica / surfactant complex. The ratio of the portion where uniform pores are formed may decrease, and the required functions may not be sufficiently exhibited. Further, the silica may form a thick layer on the surface of the silica / surfactant and adhere thereto, and the pore volume of the obtained porous body may be reduced.

The H ₂ O / Si molar ratio in an aqueous solution comprising an alkoxysilane, water and a surfactant is preferably 10 or less. The H ₂ O / Si molar ratio indicates a molar ratio of the total amount of Si to the total amount of H ₂ O (water) added at the time of mixing the raw materials. When the H ₂ O / Si molar ratio is 10 or less, the density of the manufactured high-density mesoporous body can be increased.

On the other hand, when the molar ratio of H ₂ O / Si is greater than 10, for example, the gap between the silica fine particles generated by hydrolysis and condensation of alkoxysilane becomes large, and The density may decrease.

Further, it is preferable that the H ₂ O / Si molar ratio is 1 or more. If it is less than 1, there is a possibility that hydrolysis of the alkoxysilane does not occur, silica is not generated, and a high-density mesoporous body cannot be obtained.

The method of mixing the aqueous solution is not particularly limited, but it is preferable to first add water to the alkoxysilane, stir at room temperature for 10 minutes to 3 hours, and then add a surfactant. The amount of water to be added is preferably 0.5 to 10 mol based on 1 mol of silicon contained in the alkoxysilane. Thereby, by effecting the slow condensation of the alkoxysilane through the linear alkoxysilane polymer, a dense silica structure is formed and the effect of increasing the density can be obtained.

If the amount of water is less than 0.5 mol, the hydrolysis of the alkoxysilane becomes insufficient, so that a strong high-density mesoporous skeleton is not formed or the density of the porous body is reduced. There is a risk. On the other hand, if more than 10 moles are added, hydrolysis and condensation of the alkoxysilane are rapidly performed, the silica structure becomes coarse, and the density of the high-density mesoporous body may decrease.

If the stirring time is less than 10 minutes, the density of the high-density mesoporous material may decrease. On the other hand, when the time exceeds 3 hours, uniform pores may not be formed.

Further, in the above mixing, it is preferable to add a small amount of acid as a pH adjuster. Thereby, each component is easily dissolved, and a uniform solution is easily prepared. It is preferable to adjust the pH of the aqueous solution at the time of mixing to a range of 1 to 4. If the pH is less than 1, hydrolysis and condensation proceed rapidly, and the formation of uniform pores may be hindered. Alternatively, the density of the generated porous body may be reduced. On the other hand, when the above-mentioned pH is higher than 4, the components may not be sufficiently dissolved, and the necessary hydrolysis may not be performed.

More preferably, the pH of the aqueous solution is 3-4. Thereby, hydrolysis of the alkoxysilane proceeds smoothly, and a porous body having uniform pores can be obtained. On the other hand, when the pH is less than 3, it is necessary to add a high concentration of acid. Since the hydrolysis reaction with an acid proceeds by an exothermic reaction, the addition of a high-concentration acid may cause the reaction to occur rapidly, causing bumping and increasing the risk. Also,
If the reaction occurs rapidly, the pores may not be formed uniformly. Further, the pH of the aqueous solution is adjusted to 3 using a high concentration of acid.
If it is lowered too low, a large amount of alkali is required for gelling. Therefore, the raw material cost increases, and the uniformity of the structure of the porous body may be lost due to the addition of alkali.

As the acid, dilute hydrochloric acid (for example, about 2N) can be used, but other acids such as sulfuric acid may be used. After the addition of the surfactant, it is preferable to stir for 1 hour or more in order to form a uniform micelle structure between the alkoxysilane and the surfactant.

Next, the gelation reaction of the mixture will be described. After mixing the aqueous solution comprising the alkoxysilane, water and the surfactant, the mixture is gelled by promoting the condensation reaction of silica. The resulting gel incorporates a surfactant to form a silica / surfactant complex. A mixture using an alkoxysilane having an acid value as described in claim 1 (eg, tetramethoxysilane) does not gel even if left as it is,
If it is 5 or more, gelation occurs promptly. Aqueous solution p
In order to increase H, it is necessary to add an alkaline solution.

It is preferable that the alkaline solution has a concentration of 2N (N) or less. Thereby, the condensation reaction can proceed smoothly, and a porous body having a uniform structure can be synthesized. On the other hand, if it exceeds 2N, the reaction may occur rapidly and partially, and thus pores may not be formed uniformly. As the alkali used, for example, Na
OH, NH ₃ , KOH and the like.

The alkali is used as a solution dissolved in methanol, ethanol, water or the like. In particular, in order to cause gelation uniformly, an alcohol solution of the same type as the alkoxysilane used is preferable.

Further, according to the present invention, a film-like high-density mesoporous material can be obtained. An aqueous solution containing an alkoxysilane, water and a surfactant is coated on a substrate made of aluminum or the like, and left. Thereby, the aqueous solution gels on the substrate, and a silica / surfactant composite in the form of a film can be obtained. As a method of coating the substrate with the aqueous solution, a spin coating method, a casting method, a dip coating method, or the like can be used.

Next, the powdery or film-form silica /
The surfactant is removed from the surfactant complex to form a high-density mesoporous material. Examples of the removal method include a method using baking and a method using a solvent.

First, a removing method by firing will be described. The silica / surfactant composite is heated in the range of 400C to 1000C, preferably in the range of 500C to 700C. If the heating time is 30 minutes or more, the surfactant can be removed to a degree that does not hinder practical use. However, in order to completely remove the surfactant from the silica / surfactant composite, it is preferable to heat for 1 hour or more.

If the heating temperature is lower than 400 ° C., the temperature is too low, so that the surfactant may not be sufficiently removed by burning. On the other hand, when the heating temperature exceeds 1000 ° C., the temperature is too high, and the pore structure may be collapsed. The atmosphere for the heating may be air. However, since a large amount of combustion gas is generated, the initial stage of heating is
It is more preferable to flow an inert gas such as nitrogen gas.

Next, a removing method using a solvent will be described. First, a solvent is prepared by adding a small amount of a cation component to a solvent having a high solubility for a surfactant. The silica / surfactant composite is dispersed in the solvent and stirred. Thereby, the surfactant is dissolved in the solvent and separated from the silica / surfactant composite. Then, the solid content is recovered from the solvent. The solid content is a high-density mesoporous body.

Examples of the solvent include ethanol,
Alcohol such as methanol, and acetone or the like can be used. In order to add the cation component to the solvent, it is preferable to add the following substances to the solvent. As the above substances, hydrochloric acid, acetic acid, sodium chloride, potassium chloride and the like can be used. Thereby, the surfactant can be more efficiently separated from the silica / surfactant composite.

The concentration of the cation is preferably 0.1 to 10 mol / l with respect to the solvent. When the addition concentration is less than 0.1 mol / liter, the separation of the surfactant is insufficient, and the surfactant may remain in the high-density mesoporous material.
On the other hand, if the above concentration is more than 10 mol / liter, there is no effect of further addition, and there is a possibility that the cost is increased. In addition, the silica skeleton of the high-density mesoporous material may collapse.

Next, the dispersion amount of the silica / surfactant composite in the above solvent is 0.5 to 0.5 per 100 cc of the solvent.
Preferably, it is 50 g. If the amount is less than 0.5 g, the processing efficiency of the silica / surfactant composite is poor, and the cost of the solvent and the production cost may be high. on the other hand,
If the amount is more than 50 g, the surfactant may not be sufficiently separated, and the surfactant may remain in the high-density mesoporous material.

The stirring after dispersing the silica / surfactant composite in the above-mentioned solvent is preferably performed in a temperature range of 25 to 100 ° C. As a result, the processing time for separating the surfactant can be reduced. If the temperature is lower than 25 ° C., there is a possibility that a reduction in processing time is not expected. On the other hand, when the temperature exceeds 100 ° C., energy cost for heating is required, or loss due to evaporation of the solvent may increase.

The above high-density mesoporous material can be made into a powder, sieved for each particle size, or formed into a shape according to the purpose of use. These sieving and forming steps can be performed before the step of removing the surfactant. In this case, it is possible to obtain an effect of preventing collapse of the pores during molding or improving molding strength.

After the silica / surfactant is formed into the finally required shape, the surfactant can be removed to obtain a high-density mesoporous material. In this case, collapse of the pores during molding can be prevented. Also, the molding strength can be increased.

According to the production method of the present invention, for example, a high-density mesoporous material described below can be obtained. That is, in the high-density mesoporous material, the pore diameter showing the maximum peak in the pore diameter distribution curve is in the range of 1 to 10 nm, and the pore diameter showing the maximum peak in the pore diameter distribution curve is -40 to 40.
It is preferable that 60% or more of the total pore volume is included in the pore diameter range of + 40%, and the bulk density is 0.5 g / cc or more. A high-density mesoporous material that satisfies such conditions is constituted by, for example, as shown in FIG. 1, a collection of submicron-order primary particles 11 having a large number of pores, and a gap between the primary particles. 10 is very small or almost absent.

On the other hand, a mesoporous material having a low bulk density has a structure having a large gap 90 between primary particles 91 on the order of submicrons as described above, as shown in FIG. The adsorption characteristics or catalytic characteristics specific to the high-density mesoporous material are mainly exhibited by the pores inside the primary particles. In the high-density mesoporous material, the gap between the primary particles, which is not related to the development of the adsorption property or catalytic property, is very small,
Or it has a structure that hardly exists. For this reason, in a high-density mesoporous material, a structure having a high bulk density can be realized without impairing the adsorption characteristics or the catalytic characteristics. Therefore, it has high bulk density, uniform pore size,
When used as an adsorbent, a catalyst, or the like, a high-density mesoporous material that can sufficiently exhibit its characteristics can be obtained.

The above will be described in more detail. First, the relative vapor pressure (P / P0) is 0.1 to 0.8 in the adsorption isotherm of water vapor in the high-density mesoporous material.
It is generally known that water vapor adsorption / desorption occurs rapidly in No. 1. Whether or not the adsorption isotherm of a specific high-density mesoporous material satisfies the above condition can be derived from the relationship between the pore diameter and the relative vapor pressure in the Kelvin equation.

Here, the Kelvin equation is an equation showing the relationship between the pore radius (r) of the high density mesoporous material and the relative vapor pressure (P / P0) at which the adsorbate causes capillary condensation. It can be shown by equation (1). ln (P / P0) = (2VLγcosθ) / (rRT). . . (1) where VL is the molar volume when the adsorbate is liquid, γ is the surface tension when the adsorbate is liquid, θ is the contact angle, R is the gas constant, and T is the absolute temperature. is there.

If the adsorbate is water vapor, V
L = 18.05 · 10 ⁻⁶ m ^{3 /} mol, γ = 72.59
・ 10 ^-3 N / m, R = 8.3143J / deg ・ mo
The numerical value of l, θ = 0 can be substituted into equation (1). As a result, the above equation (1) becomes the following equation (2): ln (P / P0) = − 1.058 / r. . . (2) The unit of r is nm.

From the above equation (2), in the pore size distribution,
It can be seen that when the pore diameter is distributed in a narrower range, the adsorption / desorption of water vapor occurs in a narrower range of P / P0. In other words, in the adsorption isotherm, the difference between P / P0 where adsorption rises and P / P0 where adsorption reaches saturation is small.

The high-density mesoporous material has a pore diameter of 1-1.
It is in the range of 0 nm. According to the above equation (2), when the pore diameter is in the range of 1 to 10 nm, the range of P / P0 at which the adsorption / desorption of water vapor in the adsorption isotherm is 0.
It turns out that it becomes 12-0.81. This range is a range in which the adsorption / desorption of water vapor occurs rapidly, as described above. Thereby, the high-density mesoporous material (P / P0 is 0.
(In the range of 12 to 0.81), it can be seen that the amount of adsorption is largely changed by a small change of P / P0, which is optimal as an adsorbent in an adsorption heat pump, a temperature controller and the like.

The pore distribution curve will be described below.
The pore diameter distribution curve is a curve in which a value (dV / dD) obtained by differentiating the pore volume (V) of the high-density mesoporous material with the pore diameter (D) is plotted against the pore diameter (D). (FIG. 3
reference). The pore size distribution curve can be created, for example, by the gas adsorption method described below. The most frequently used gas in the above gas adsorption method is nitrogen, but methanol vapor having a relatively small molecular diameter and easily adsorbing at around normal temperature is also often used.

The methanol adsorption type pore distribution measuring method will be described. First, methanol vapor is introduced into the target high-density mesoporous material at room temperature. The inlet pressure is gradually increased, and the amount of methanol adsorbed for each equilibrium pressure is plotted to create an isotherm. From this isotherm, the above pore distribution curve is obtained by calculation using the formula of Urano et al.

Next, the expression "the diameter range of + -40% of the diameter showing the maximum peak in the pore diameter distribution curve includes 60% or more of the total pore volume" is as follows. Expresses the state. For example, it is assumed that the high-density mesoporous material α has a maximum peak of 2.7 nm in the above-described pore diameter distribution curve. In this high-density mesoporous material α, the pore diameter is 1.62 (= 2.7 × 0.6) to 3.78.
The pore volume V is obtained by summing the volumes of the pores in the range of (= 2.7 × 1.4) nm. On the other hand, in the high-density mesoporous material α, the total value of the total pore volume Val is obtained.

If the value of V / Val is assumed to be 0.6
(60%) or more, it can be said that the high density mesoporous body α is one of the high density mesoporous bodies. Alternatively, in the pore size distribution curve of the high-density mesoporous material α, the integral value in the range where the pore size is 1.62 to 3.78 nm is:
Even when it is 60% or more of the total integrated area of the pore diameter distribution curve, it can be said that the high density mesoporous material α is a high density mesoporous material.

The high-density mesoporous material satisfying such conditions has a small P /
The effect that the amount of adsorption greatly changes with respect to the change of P0 can be obtained. In addition, in the diameter range of + -40% of the diameter showing the maximum peak in the pore diameter distribution curve,
If less than 60% of the total pore volume is contained, the change in the adsorption amount with respect to the change in P / P0 is small, and the humidity control function and the adsorption heat pump characteristics may not be sufficiently exhibited.

The bulk density of the high-density mesoporous material is 0.5
g / cc or more. Therefore, when the high-density mesoporous material is used as an adsorbent or a catalyst, a larger amount of the high-density mesoporous material can be filled in a filling container or the like. Thereby, it is possible to exhibit high adsorption characteristics or catalytic characteristics. Alternatively, it is possible to reduce the size of a high-density mesoporous filled container or the like, and to reduce the size of an apparatus for setting the filled container or the like.

The pore diameter showing the maximum peak in the pore diameter distribution curve is in the range of 1 to 10 nm, and the change in the amount of adsorption when the relative vapor pressure changes by 0.2 in the water vapor adsorption isotherm is 0. It preferably has a portion of 0.1 g / cc or more. As a result, the effect that humidity control and adsorption heat pump characteristics are exhibited with a smaller amount of the porous body can be obtained. The change in the amount of adsorption was 0.1 g.
If it is less than / cc, a large amount of porous body is required, which may cause a problem that the size of the filling container and the entire device is increased.

The above-mentioned "the amount of change in the amount of adsorption when the relative vapor pressure changes by 0.2 has a portion of 0.1 g / cc or more" means that the relative vapor pressure (P / P
When 0) is 0.1 and 0.3, the adsorption amount is V _0.1 =
Assuming that 0.2 g / cc and V _0.3 = 0.5 g / cc, the change in the adsorption amount when the relative vapor pressure changes by 0.2 is V _0.3 −V _0.1 = 0.3 g / cc, and “0 .1g /
cc or more ". The change in the relative vapor pressure may be in any range of 0 to 1, and the portion where the change in the adsorption amount is 0.1 g / cc or more may be only a part of the high-density mesoporous material.

Next, the high-density mesoporous material has a
It is preferable that at least t% be composed of silicon and oxygen. As a result, the bond between the adsorbed molecule (eg, water molecule) and the surface of the porous body becomes relatively weak, and the adsorbed molecule is relatively easily desorbed, so that the adsorption and desorption can be repeated reversibly. If the content of silicon and oxygen is less than 80% by weight, elements different from silicon and oxygen are mixed, solid acidity and the like appear on the surface, and the adsorbed molecules may not be easily desorbed. There is.

The high-density mesoporous material obtained by the production method of the present invention can be used as, for example, an adsorbent which can be used for recovery of a solvent or gasoline, an adsorption heat pump, temperature control, water treatment, deodorization, etc. It can be used for purification, organic synthesis, petroleum reforming and cracking, etc.

[0064]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 A method for manufacturing a high-density mesoporous body according to an embodiment of the present invention will be described. The outline is that the acid value is 0.0026.
After mixing the alkoxysilane, water and the surfactant, and gelling with an alkaline solution, the surfactant is removed.

Hereinafter, the details of the manufacturing method of this example will be described. 15 kg of TMOS-B (referred to as tetramethyl orthosilicate manufactured by Tama Chemical Co., Ltd .; hereinafter the same) as an alkoxysilane was prepared. The acid value of this TMOS-B is
When measured by the above method to neutralize the KOH solution,
It was 0.0026.

3.42 liters of water and 100 cc of 0.1N hydrochloric acid were added to 15 kg of TMOS-B, and the mixture was stirred at room temperature for about 1 hour. 12.96 kg of a methanol solution of hexadecyl ammonium chloride as a surfactant (hereinafter referred to as HDTA / methanol solution) (cation concentration: 60.7) was added to the aqueous solution obtained by the addition and stirring.
%) And stirred at room temperature for about 3 hours. The viscosity of the aqueous solution gradually increased, but did not gel at this point.

To this aqueous solution, 1.14 liter of a 0.05N NaOH / methanol solution (alkali solution) was added with stirring. The viscosity of the aqueous solution further increases and the pH becomes 5
It began to gel rapidly in the vicinity. The obtained gel was left in a closed container at room temperature for 24 hours or more. This state is a silica / surfactant composite.

The gel after standing was air-dried for 24 hours or more, and further dried at 110 ° C. for 12 hours or more. After that, 55
Calcination was performed in air at 0 ° C. for 4 hours to remove the surfactant from the silica / surfactant composite. The solid obtained by calcination is pulverized and sieved to a particle size of 100-1.
A powdery high-density mesoporous body of 50 μm was obtained. This is designated as Sample 1.

Embodiment 2 In this embodiment, a high-density mesoporous body was manufactured using twice as many raw materials as those used in Embodiment 1. The ratio of the amount of each raw material used is almost the same as in the first embodiment.

Hereinafter, the details of the manufacturing method of this embodiment will be described. To 30 kg of TMOS-B, 6.84 liters of water and 200 cc of 0.1 N hydrochloric acid were added, and the mixture was stirred at room temperature for about 2 hours. H 2 was added to the aqueous solution obtained by this addition and stirring.
26 kg of DTA / methanol solution (cation concentration 60.
7%) and stirred at room temperature for about 4 hours. The viscosity of the aqueous solution gradually increased, but did not gel at this point.

To this aqueous solution, 2.28 liters of a 0.05N NaOH / methanol solution (alkali solution) was added with stirring. The viscosity of the aqueous solution further increases and the pH becomes 5
It began to gel rapidly in the vicinity. The obtained gel was left in a closed container at room temperature for 36 hours or more. This state is a silica / surfactant composite.

The gel after standing was air-dried for 24 hours or more, and further dried at 440 ° C. for 10 hours. Then, at 550 ° C
For 4 hours in air to remove the surfactant from the silica / surfactant composite. The solid obtained by firing is crushed and sieved to a particle size of 100 to 150.
A μm powdery high-density mesoporous material was obtained. This is sample 2
And

Embodiments 3 to 6 In this embodiment, a high-density mesoporous body was manufactured in the same manner as in Embodiment 2. This is to investigate the reproducibility of the method of the second embodiment. The obtained high-density mesoporous materials are referred to as samples 3 to 6, respectively.

Embodiment 7 In this embodiment, the same raw materials as those used in Embodiment 1 were used.
A high-density mesoporous material was manufactured by changing the amount of the mesoporous material.

That is, 68 g of water and 4 cc of 0.1 N hydrochloric acid were added to 304 g of TMOS-B, followed by stirring at room temperature for about 1 hour. 257 g (cation concentration: 61%) of a methanol solution of dodecyltrimethylammonium chloride (DDTA / methanol solution) was further added to the aqueous solution obtained by the addition and stirring, followed by stirring at room temperature for about 4 hours. The viscosity of the aqueous solution gradually increased, but did not gel at this point.

To this aqueous solution, 10 cc of a 0.05 N NaOH / methanol solution (alkali solution) was added with stirring. The viscosity of the aqueous solution further increased, and gelling started rapidly when the pH reached around 5. The obtained gel was left in a closed container at room temperature for 36 hours or more. This state is a silica / surfactant composite.

The gel after standing was dried at 110 ° C. for 12 hours or more, and calcined at 550 ° C. for 4 hours in air to remove the surfactant from the silica / surfactant composite. The solid obtained by firing was pulverized and sieved to obtain a powdery high-density mesoporous material having a particle size of 100 to 150 µm. This is designated as Sample 7.

Embodiment 8 In this embodiment, a high-density mesoporous body was manufactured using C18 (stearyltrimethylammonium chloride having 18 carbon atoms) as a surfactant. That is, 6.8 g of water and 0.4 cc of 0.1 N hydrochloric acid were added to 30.4 g of tetramethoxysilane (TMOS), which was an alkoxysilane, and the mixture was stirred at room temperature for about 1 hour. A methanol solution (STMA / methanol solution) of surfactant stearyltrimethylammonium chloride (cation concentration: 63.5%) was further added to the solution obtained by the addition and stirring, followed by stirring at room temperature for about 4 hours. 0.05N NaO was added to this solution.
4 cc of H / methanol solution was added under stirring. The subsequent operation is the same as in the other embodiments. The resulting high-density mesoporous material is referred to as Sample 8. The specific surface area of Sample 8 was 1168
(M ² / g).

Experimental Example 1 The high-density mesoporous materials of Samples 1 to 3, 5 to 8 were measured for their water vapor adsorption isotherms. The water vapor adsorption isotherm was measured at 25 ° C. by the constant volume method using BELSORP18 manufactured by Nippon Bell.

The measurement results are shown in FIGS. FIG.
(A) and FIG. 3 (b) show the measurement results of sample 1 and sample 2,
4 (c), 4 (d) and 4 (e) show the measurement results of sample 3, sample 5 and sample 6, and FIGS. 5 (f) and 5 (g) show sample 7 and sample 8 respectively. The result of the measurement was shown. In these figures,
■ indicates a water vapor adsorption isotherm at the time of adsorption, and ○ indicates a water vapor adsorption isotherm at the time of desorption.

As can be seen from these figures, Sample 1, Sample 2 and Sample 7, which use different scales of raw materials, all exhibited the same adsorption state. Samples 2 and 3 manufactured under the same conditions
5 and 6 also showed the same adsorption state. From this, it can be seen that the production method of the present invention can obtain almost the same result regardless of the scale up or down, and has high reproducibility. Further, with respect to the high-density mesoporous materials of Samples 2 and 3 manufactured under the same conditions, hysteresis is observed at the time of adsorption and desorption, indicating that relatively large pores are formed.

Experimental Example 2 The pore distribution curves of the high-density mesoporous materials of Samples 2 to 6 were measured using an AS-703b methanol adsorber manufactured by Tanaka Chemical Instruments Co., Ltd. FIG. 6 shows the differential pore distribution obtained from the results. From FIG. 6, samples 2 to 6 manufactured under the same conditions are shown.
It can be seen that the high density mesoporous material has pores of almost the same size.

Experimental Example 3 The specific surface area, pore volume,
The packing density and pore radius were determined. The specific surface area was determined by the BET one point method using an automatic specific surface area measuring device of Okura Riken. The pore volume and the pore radius were determined from the pore distribution curve of Experimental Example 2. The packing density was calculated from the weight and volume after vacuum drying. The physical properties are shown in Table 1.

As can be seen from the table, samples 2 to 6, 8
It can be seen that all show similar physical property values. on the other hand,
Sample 7 had smaller pore volume and smaller pore radius and higher packing density than the other samples. This is considered to be because the formed pores became small because the surfactant having 12 carbon atoms was used.

[0085]

[Table 1]

[0086]

According to the present invention, it is possible to provide a method for producing a high-density mesoporous body having a uniform pore diameter and excellent reproducibility.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a high-density mesoporous body of the present invention.

FIG. 2 is an explanatory view of a conventional high-density mesoporous body.

3A is a diagram showing a water vapor adsorption isotherm of a sample 1, and FIG. 3B is a diagram showing a water vapor adsorption isotherm of a sample 1.

4 (c) is a diagram showing a water vapor adsorption isotherm of sample 3, FIG. 4 (d) is a diagram showing a water vapor adsorption isotherm of sample 5, and FIG. FIG.

5 (f) is a diagram showing a water vapor adsorption isotherm of sample 7, and FIG. 5 (g) is a diagram showing a water vapor adsorption isotherm of sample 8 in Experimental Example 1.

FIG. 6 is a diagram showing differential pore distribution curves of Samples 2 to 6 in Experimental Example 2.

[Explanation of symbols]

 10. . . Gap, 11. . . Primary particles,

Continuing from the front page (72) Inventor Shinji Inagaki 41, Chukumi Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside the Toyota Central R & D Laboratories Co., Ltd. No. 1 Inside Toyota Central Research Laboratories Co., Ltd. (72) Inventor Noriaki Sugimoto 41-cho, Yokomichi Omachi, Nagakute-cho, Aichi-gun, Aichi Prefecture No. 1 Inside Toyota Central Research Laboratories Co., Ltd. 7800, Chihama, Higashi-cho, Cataler Industry Co., Ltd.

Claims (1)

[Claims] 1. A method for producing a high-density mesoporous material obtained by mixing an alkoxysilane, water and a surfactant, gelling the mixture, and then removing the surfactant, wherein the alkoxysilane is an acid. A method for producing a high-density mesoporous body, wherein the value is 0.0045 or less.