JP2019147099A - CO2 adsorbent - Google Patents

Abstract

To provide COadsorbent capable of efficiently adsorbing COat a temperature range of relatively high temperature.SOLUTION: There is provided a COadsorbent consisting of an organic silica porous body having a structure represented by a specific general formula in which a basic functional group binds to silicon in a skeleton of the porous body, a specific surface calculated based on nitrogen adsorption isotherm of the porous of 1 to 30 m/g and a value ([mass ratio of an organic component]/[average pore diameter of a sample]) calculated by dividing the mass ratio of the organic component in the porous body by the average pore diameter of the sample calculated based on the adsorption isotherm of the samples obtained by a heat treatment at 550°C for 6 hr. of the porous body of 0.06/nm or more.SELECTED DRAWING: None

Description

The present invention relates to a CO ₂ adsorbent.

In recent years, in order to reduce the emission of carbon dioxide (CO ₂ ), which is one of the greenhouse gases from the viewpoint of environmental impact, development of a CO ₂ adsorbent for separating and recovering CO ₂ in gas has been advanced. Yes. For example, in Japanese Patent Application Laid-Open No. 2012-139622 (Patent Document 1), a formula: RNH (CH ₂ ) _p OH [wherein R represents an alkyl group having 1 to 6 carbon atoms] with respect to a support such as silica. , P represents 2-5. The carbon dioxide absorber which supported the alkanolamine represented by this is described.

JP 2012-139622 A

However, such a carbon dioxide absorbent as described in Patent Document 1 decreases in adsorption performance as the temperature rises, and in a relatively high temperature range (for example, a temperature range of about 60 ° C. or higher). The adsorption performance of CO ₂ was not sufficient. In the field of CO ₂ adsorbent, for example, the temperature of exhaust gas from a power plant is generally about 50 to 75 ° C., the temperature of exhaust gas from an automobile is generally about 70 to 90 ° C., etc. from the appearance of a relatively high temperature of higher CO ₂ adsorbent adsorbing performance of CO ₂ in the temperature range it is desired.

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a CO ₂ adsorbent capable of sufficiently adsorbing CO ₂ in a relatively high temperature range.

The present inventors have found that the result of intensive to achieve intensive research purposes, the CO ₂ adsorbent consisting of an organic silica-based porous body, such organic silica porous material, bases in the silicon in the skeleton of the porous body Having a specific structure represented by the following general formula (1) to which a functional functional group is bonded, the specific surface area determined based on the nitrogen adsorption isotherm of the porous body being 1 to 30 m ² / g, A value obtained by dividing the mass ratio of organic components in the body by the average pore diameter of the sample obtained based on the nitrogen adsorption isotherm of the sample obtained by heating the porous body at 550 ° C. for 6 hours. By setting ([mass ratio of organic component] / [average pore diameter of sample]) to 0.06 / nm or more, it is possible to sufficiently adsorb CO ₂ in a relatively high temperature range. The headline and the present invention were completed.

That, CO ₂ adsorbent of the present invention is a CO ₂ adsorbent consisting of an organic silica-based porous body,
The organosilica-based porous body is
The following general formula (1) in which a basic functional group is bonded to silicon in the skeleton of the porous body:
X-Si (1)
[In the formula (1), X represents the formula: R ¹ —NH— (CH ₂ ) _n — (wherein R ¹ is any one selected from the group consisting of a hydrogen atom, an aminoalkyl group, and an aminoalkylaminoalkyl group. And n represents an integer of 1 to 6.) represents a basic functional group. ]
Having a structure represented by
The specific surface area determined based on the nitrogen adsorption isotherm of the porous body is 1 to 30 m ² / g,
The mass ratio of the organic component in the porous body is obtained by dividing by the average pore diameter of the sample obtained based on the nitrogen adsorption isotherm of the sample obtained by heating the porous body at 550 ° C. for 6 hours. The obtained value ([mass ratio of organic components] / [average pore diameter of sample]) is 0.06 / nm or more,
It is characterized by.

The CO ₂ adsorbent of the present invention comprises R ¹ as a hydrogen atom, an aminoalkyl group having 1 to 5 carbon atoms, and an aminoalkylaminoalkyl group in which the aminoalkyl moiety has 1 to 5 carbon atoms. It is preferably any one selected from the group.

The CO ₂ adsorbent of the present invention has any basicity wherein X in the general formula (1) is selected from the group consisting of aminopropyl group, aminoethylaminopropyl group, and aminoethylaminoethylaminopropyl group It is preferably a functional group.

The reason why the CO ₂ adsorbent of the present invention can sufficiently adsorb CO ₂ in a relatively high temperature range is not necessarily clear, but the present inventors speculate as follows. That is, first, the organic silica-based porous material according to the present invention has a base represented by the specific basic functional group (formula: R ¹ —NH— (CH ₂ ) _n —) on silicon (Si) in the skeleton. A functional group). Therefore, the CO ₂ adsorbent of the present invention composed of such an organic silica-based porous body has increased affinity with CO ₂ due to the basic functional group, and can sufficiently adsorb CO ₂ . Further, the organic silica-based porous body is obtained by determining the mass ratio of organic components in the porous body based on a nitrogen adsorption isotherm of a sample obtained by heat-treating the porous body at 550 ° C. for 6 hours. The value ([mass ratio of organic components] / [average pore size of sample]) obtained by dividing by the average pore diameter is 0.06 / nm or more (hereinafter, the formula: [organic component The mass ratio] / [average pore diameter of sample] is simply referred to as “organic component ratio per average pore diameter” for convenience. The organic component ratio ([mass ratio of organic component] / [average pore diameter of sample]) per average pore diameter is such that the organic component (basic functional group) per each pore of the organic silica-based porous body. It is possible to determine that a sufficient amount of a basic functional group having a high affinity with CO ₂ is introduced as the value increases. When the organic component ratio ([mass ratio of organic components] / [average pore diameter of sample]) per average pore diameter is 0.06 / nm or more, the basic functionality into each pore is The introduction amount of the group is a sufficiently high ratio, and CO ₂ can be sufficiently adsorbed. In addition, in the organic silica-based porous body, when the organic component ratio ([mass ratio of organic components] / [average pore diameter of sample]) per average pore diameter is 0.06 / nm or more, the basicity The present inventors speculate that the introduction of other gases (for example, nitrogen (N ₂ ) or water vapor) into the pores can be sufficiently suppressed because the pore diameter is reduced by the influence of the functional group. . Therefore, the CO ₂ adsorbent of the present invention composed of the above-mentioned organic silica-based porous body has a basic functional group while sufficiently suppressing the introduction of other gases (for example, nitrogen (N ₂ ) and water vapor) into the pores. The present inventors speculate that it is possible to selectively introduce CO ₂ into the pores due to the high affinity with CO _{2 and} to sufficiently adsorb and separate CO ₂ . The organosilica porous body has a specific surface area of 1 to 30 m ² / g determined based on the nitrogen adsorption isotherm of the porous body. Thus, if the organic silica-based porous body has a specific surface area of 1-30 m 2 / ^g, since the pore size is reduced, other gases into the pores (e.g. nitrogen (N ₂₎ Or water vapor) can be more efficiently suppressed. Therefore, according to the CO ₂ adsorbent of the present invention, it is possible to sufficiently adsorb and separate CO ₂ in a relatively high temperature range while sufficiently suppressing the adsorption of other gases. The inventors speculate.

The present inventors have found that the exhaust gas (e.g., exhaust gas from the power plant) CO ₂ from the time of removal by adsorption on adsorbent, most problems when the steam and CO ₂ coexist in the exhaust gas It is considered that the adsorption amount of CO ₂ is significantly reduced due to the preferential adsorption of coexisting water vapor. That is, when water vapor and other gases (including CO ₂ ) coexist in the exhaust gas, since water vapor has a higher boiling point than other gases, it is more easily adsorbed than other gases, and the conventional porous when using the body as a CO ₂ adsorbent, therefore the CO ₂ vapor adsorbed by the adsorbent occurs preferentially, as a result that CO ₂ adsorption amount is reduced considerably and the present inventors believe Yes. Here, in general, when gas is adsorbed to a conventional silica-based porous body, gas adsorption is likely to occur at a lower temperature, and the amount of gas adsorption tends to decrease as the adsorption temperature increases. The same applies to water vapor, and in a conventional silica-based porous body, the amount of water vapor adsorbed tends to decrease at high temperatures. Thus, in general, when a conventional porous body is a CO ₂ adsorbent, the amount of adsorption of water vapor decreases at a high temperature, so that the amount of CO ₂ adsorption at a high temperature can be increased. The present inventors infer that the porous body of the system makes it possible to further increase the CO ₂ adsorption selectivity even in the presence of water vapor and CO ₂ . Here, the CO ₂ adsorbent of the present invention has a sufficiently high CO ₂ adsorption amount under relatively high temperature conditions in which the adsorption amount of water vapor decreases. Therefore, the CO ₂ adsorbent of the present invention can selectively adsorb CO ₂ from a mixed gas of water vapor or the like and CO _2, and increase CO ₂ adsorption selectivity more than a conventional porous body. The present inventors speculate that this is possible. As described above, the reason why the organic silica-based porous material according to the present invention has a sufficiently high CO ₂ adsorption amount under relatively high temperature conditions is not necessarily clear. Since the movement of the basic functional group introduced with the increase becomes more active, the function as a pore becomes higher, and the adsorption amount of CO ₂ under a high temperature condition becomes sufficiently high. The present inventors speculate that this is caused by the above. Therefore, CO ₂ adsorbent of the present invention, even in the presence of water vapor and CO _2, and it is possible to exhibit the adsorption of sufficiently high CO ₂ present inventors speculate.

According to the present invention, it is possible to provide a CO ₂ adsorbent that can sufficiently adsorb CO ₂ in a relatively high temperature range.

₂ is a graph showing a CO ₂ adsorption isotherm of a porous body obtained in Example 1. FIG. 3 is a graph showing a CO ₂ adsorption isotherm of a porous body obtained in Example 2. 6 is a graph showing a CO ₂ adsorption isotherm of a porous body obtained in Example 3. 6 is a graph showing a CO ₂ adsorption isotherm of a porous body obtained in Example 4. 6 is a graph showing a CO ₂ adsorption isotherm of a porous body obtained in Example 5. 4 is a graph showing a CO ₂ adsorption isotherm of a porous body obtained in Comparative Example 1. 6 is a graph showing a CO ₂ adsorption isotherm of a porous body obtained in Comparative Example 2. 6 is a graph showing a CO ₂ adsorption isotherm of a porous body obtained in Comparative Example 3.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

CO ₂ adsorbent of the present invention is a CO ₂ adsorbent consisting of an organic silica-based porous body,
The organosilica-based porous body is
The following general formula (1) in which a basic functional group is bonded to silicon in the skeleton of the porous body:
X-Si (1)
[In the formula (1), X represents the formula: R ¹ —NH— (CH ₂ ) _n — (wherein R ¹ is any one selected from the group consisting of a hydrogen atom, an aminoalkyl group, and an aminoalkylaminoalkyl group. And n represents an integer of 1 to 6.) represents a basic functional group. ]
Having a structure represented by
The specific surface area determined based on the nitrogen adsorption isotherm of the porous body is 1 to 30 m ² / g,
The mass ratio of the organic component in the porous body is obtained by dividing by the average pore diameter of the sample obtained based on the nitrogen adsorption isotherm of the sample obtained by heating the porous body at 550 ° C. for 6 hours. The obtained value ([mass ratio of organic components] / [average pore diameter of sample]) is 0.06 / nm or more,
It is characterized by.

Such an organic silica-based porous body has the following general formula (1) in which a basic functional group is bonded to silicon in the skeleton:
X-Si (1)
[In the formula (1), X represents the formula: R ¹ —NH— (CH ₂ ) _n — (wherein R ¹ is any one selected from the group consisting of a hydrogen atom, an aminoalkyl group, and an aminoalkylaminoalkyl group. And n represents an integer of 1 to 6.) represents a basic functional group. ]
It has the structure represented by these. Thus, the organic silica porous body according to the present invention has a structure in which the basic functional group (X) is bonded to silicon (Si) in the skeleton, and the basic functional group is CO _2. Since it is a group having a high affinity for CO ₂ , it is possible to make the CO ₂ adsorption performance higher due to the basic functional group. In addition, since the basic functional group (X) is bonded to silicon (Si) in the skeleton as described above, it is heated to about 180 ° C. in order to recover CO ₂ when the CO ₂ adsorbent is reused. Even in this case, it is possible to sufficiently suppress the elimination of the basic functional group, and thus it is possible to exhibit sufficiently high heat resistance with respect to the CO ₂ adsorption performance. An organic silica-based porous body (silica-based porous body having an organic group) in which such a basic functional group is bonded to silicon in the skeleton is silica-based using a basic functional group-containing trialkoxysilane described later. It can manufacture efficiently by manufacturing a porous body.

Such a basic functional group (the group represented by X in the above general formula (1)) is a group represented by the formula: R ¹ —NH— (CH ₂ ) _n —. R ^{1 in} the formula of such a basic functional group is any selected from the group consisting of a hydrogen atom, an aminoalkyl group and an aminoalkylaminoalkyl group.

The aminoalkyl group that can be selected as R ¹ preferably has 1 to 5 carbon atoms, more preferably 2 to 4, and still more preferably 2 to 3. If the number of carbons exceeds the upper limit, the amount of amino groups in the pores tends to decrease, so the amount of CO ₂ adsorbed tends to decrease. It tends to be difficult to synthesize a trialkoxysilane having a content (it is difficult to synthesize and obtain raw materials). The aminoalkyl group that can be selected as R ¹ is more preferably an aminoethyl group or aminopropyl group, and particularly preferably an aminoethyl group.

The aminoalkylaminoalkyl group that can be selected as R ¹ preferably has 1 to 5 carbon atoms, more preferably 2 to 4, and more preferably 2 to 3 carbon atoms in each aminoalkyl moiety. Further preferred. If the number of carbons exceeds the upper limit, the amount of amino groups in the pores tends to decrease, so the amount of CO ₂ adsorbed tends to decrease. It tends to be difficult to synthesize a trialkoxysilane having the above. The aminoalkylaminoalkyl group that can be selected as R ¹ is more preferably an aminoethylaminoethyl group or aminopropylaminopropyl group, particularly preferably an aminoethylaminoethyl group.

As such R ¹ , among them, from the viewpoint of more uniformly dispersing amino groups in the pores, a hydrogen atom and a carbon number of 1 to 5 (more preferably 1 to 4, particularly preferably 2 to 3). The aminoalkyl group and the aminoalkyl moiety are preferably aminoalkylaminoalkyl groups having 1 to 5 carbon atoms (more preferably 1 to 4, particularly preferably 2 to 3).

_{N in the} formula of the basic functional group (formula: group represented by R ¹ —NH— (CH ₂ ) _n —) is 1 to 6 (more preferably 2 to 5, more preferably 3 to 4). ). If the value of n exceeds the above upper limit, the amount of amino groups in the pores tends to decrease, so that the amount of CO ₂ adsorbed tends to decrease. It tends to be difficult to synthesize a trialkoxysilane having a group (it is difficult to synthesize and obtain raw materials).

  Moreover, as such a basic functional group (a group represented by X in the general formula (1)), an aminopropyl group, an aminoethylaminopropyl group, and an aminoethylaminoethylaminopropyl group are preferable.

Furthermore, such an organic silica-based porous material has an average pore diameter (average) of the sample obtained based on a nitrogen adsorption isotherm of the sample obtained by heat-treating the organic silica-based porous material at 550 ° C. for 6 hours. The pore diameter is preferably 1 to 50 nm (preferably 1.2 to 20 nm). Here, the “average pore diameter of the sample” referred to in the present invention is a value measured using a sample (baked product) obtained by heat-treating the organic silica-based porous material at 550 ° C. for 6 hours. From the specific surface area (S) of the sample obtained based on the nitrogen adsorption isotherm of the sample and the pore volume (V) of the sample, the formula: D = 4 V / S [where D is the sample Mean pore diameter (average pore diameter), V represents the pore volume of the sample, and S represents the specific surface area of the sample]. . In addition, as a specific surface area (S) of such a sample, after preparing a sample (baked product) obtained by heat-treating 100 mg of an organic silica-based porous body at 550 ° C. for 6 hours, the sample is subjected to liquid nitrogen temperature ( Nitrogen gas is introduced after cooling to −196 ° C., the amount of nitrogen gas adsorbed is determined by the constant volume method (gas adsorption method) or gravimetric method, and the pressure of the introduced nitrogen gas is gradually increased to After obtaining the nitrogen adsorption isotherm of the sample by plotting the adsorption amount of nitrogen gas, a value calculated from the nitrogen adsorption isotherm of the sample using the BET isotherm equation is adopted. As the pore volume (V) of the sample, the nitrogen gas adsorption amount at P / P ₀ (relative pressure) = 0.95 is set to the standard state (pressure 100 kPa) using the nitrogen adsorption isotherm of the sample. , A nitrogen gas adsorption capacity determined by conversion to 25 ° C.). That is, the specific surface area (S) of the sample used for calculation of the average pore diameter of such a sample is a specific surface area (BET specific surface area of the sample) determined by the BET method, and the pore volume of the sample (V) is a nitrogen gas adsorption capacity obtained by converting the nitrogen adsorption amount at P / P ₀ (relative pressure) = 0.95 into a standard state. In the present invention, when the average pore diameter of the sample is assumed to be the average pore diameter of the organic silica-based porous body, and the average pore diameter of the sample is in the range of 1 to 50 nm, the porous body Can be determined to have mesopores having a pore diameter of 1 to 50 nm.

  Further, as such an organic silica-based porous body, those in which pores are formed not only on the surface of the porous body but also on the inside are preferable. The arrangement state (pore arrangement structure or structure) of the pores in the porous body is not particularly limited.

  The pore arrangement structure of such a porous body is a hexagonal structure (2d-hexagonal structure, 3d-hexagonal structure) means that the arrangement of the pores is a hexagonal structure (S. Inagaki, et al. S. Inagaki, et al., Bull. Chem. Soc. Jpn., 69, 1449, 1996, Q. Huo, et al., Science, 268, 1324, 1995). Moreover, that the pore arrangement structure of the porous body is a cubic structure means that the arrangement of the pores is a cubic structure (JC Vartuli, et al., Chem. Mater., 6, 2317, 1994; see Q. Huo, et al., Nature, 368, 317, 1994). Further, that the porous body has a disordered pore arrangement structure means that the arrangement of the pores is irregular (PT Tanev, et al., Science, 267, 865, 1995; S; A. Bagshaw, et al., Science, 269, 1242, 1995; R. Ryoo, et al., J. Phys. Chem., 100, 17718, 1996). The cubic structure is preferably Pm-3n, Im-3m or Fm-3m symmetric. The symmetry is determined based on a space group notation.

Moreover, such an organic silica type | system | group porous body is 1-30 m < ² > / g of specific surface area calculated | required based on the nitrogen adsorption isotherm of this porous body. When such a specific surface area exceeds the upper limit, the characteristic that the amount of CO ₂ adsorption increases at a high temperature tends not to be exhibited. On the other hand, when the specific surface area is less than the lower limit, sufficient CO ₂ in the gas is obtained when contacting with the gas. Can no longer be adsorbed on. Specific surface area determined based on nitrogen adsorption isotherm of such porous bodies, more preferably 1-20 m ² / g, more preferably in a 1~13m ² / g, 1~10m ² / Particularly preferred is g. By setting such a specific surface area within the above range, CO ₂ tends to be separated more efficiently while sufficiently suppressing adsorption of other gases such as water vapor. When the specific surface area exceeds the upper limit, the amount of adsorption of other gases increases, and the adsorption selectivity of CO ₂ tends to decrease. The specific surface area of such an organic silica-based porous material is such that the organic silica-based porous material is cooled to a liquid nitrogen temperature (-196 ° C.) and nitrogen gas is introduced, and a constant volume method (gas adsorption method) or By determining the adsorption amount of nitrogen gas to the organic silica porous body by a gravimetric method, gradually increasing the pressure of the introduced nitrogen gas, and plotting the adsorption amount of nitrogen gas against each equilibrium pressure, the organic silica porous After obtaining the nitrogen adsorption isotherm of the body, a value (BET specific surface area) calculated from the nitrogen adsorption isotherm of the organosilica porous body using the BET isotherm adsorption formula is adopted. That is, the specific surface area of such an organic silica-based porous material is calculated by using the BET isotherm adsorption formula from the nitrogen adsorption isotherm (the nitrogen adsorption isotherm of the porous material) obtained using the organic silica-based porous material as it is. The obtained value (specific surface area determined by the BET method: BET specific surface area) is adopted. When measuring such nitrogen adsorption isotherm, the organic silica porous material is dried in advance (for example, heated at 80 to 150 ° C. for about 2 hours under vacuum conditions (1 Pa or less)). Etc.).

The organic silica-based porous body preferably has a mass ratio (organic component ratio) of organic components in the porous body of 0.06 to 0.5, and preferably 0.08 to 0.3. More preferred. If the mass ratio of the organic component is less than the lower limit, the content of the basic functional group that is the organic component tends to be low, so that it is difficult to sufficiently adsorb CO _2. If it exceeds, the pores shrink and the amount of CO ₂ adsorbed tends to decrease. In addition, the value which can be measured as follows is employ | adopted as mass ratio (organic component ratio) of the organic component in such a porous body. That is, first, 10 mg of the organic silica-based porous material is used as a measurement sample, and the temperature is increased by 10 ° C./min in the atmosphere using a thermogravimetric measurement device (for example, trade name “Thermo Plus” manufactured by Rigaku Corporation). The thermogravimetric curve is measured in the temperature range from room temperature (25 ° C.) to 800 ° C. at a speed, and the weight fraction at 150 ° C. (the residual fraction of weight at 150 ° C., that is, the initial measurement sample) The ratio of the weight of the component remaining at 150 ° C. with respect to the weight, unit: wt%: hereinafter, sometimes simply referred to as “W1” or “weight fraction (W1)”) and the weight fraction at 600 ° C. (The residual ratio of the weight at 600 ° C., that is, the ratio of the weight of the component remaining at 600 ° C. with respect to the initial mass of the measurement sample, unit: wt%: hereinafter, sometimes simply “W2” or “weight” Fraction (W2) ”is used to simulate the weight fraction (W1) value at 150 ° C. with the weight ratio of the organic silica porous material itself in the measurement sample (the solvent in the pores is sufficiently The ratio (W1-W2) obtained by subtracting the weight fraction (W2) at 600 ° C. from the weight fraction (W1) at 150 ° C. By simulating the component ratio, the difference between the weight fraction at 150 ° C. and the weight fraction at 600 ° C. (W1−W2) is divided by the weight fraction (W1) at 150 ° C. to obtain the mass of the organic component. The ratio (organic component ratio) is obtained. Thus, in this invention, after calculating | requiring a thermogravimetric curve as mentioned above, following formula (I):
[Mass ratio of organic components] = (W1-W2) / W1 (I)
(In formula (I), W1 represents the weight fraction at 150 ° C. in the thermogravimetric curve, and W2 represents the weight fraction at 600 ° C. in the thermogravimetric curve.)
The value obtained by calculating is adopted as the mass ratio of organic components (organic component ratio).

The organic silica-based porous body is based on the nitrogen adsorption isotherm of a sample obtained by heat-treating the porous body at 550 ° C. for 6 hours based on the mass ratio (organic component ratio) of the organic components in the porous body. The value obtained by dividing by the average pore diameter of the sample obtained in this way (the organic component ratio per average pore diameter: [mass ratio of organic components (organic component ratio)] / [average pore diameter of sample]) is 0. 0.06 / nm or more (herein, “mass ratio of organic components (organic component ratio)” is a value determined by the above-described calculation formula (I)). When the value of the organic component ratio ([mass ratio of organic components] / [average pore diameter of sample]) per average pore diameter is less than the lower limit, CO ₂ cannot be sufficiently selectively separated. In addition, the value of the organic component ratio ([mass ratio of organic component] / [average pore diameter of sample]) per average pore diameter is used to confirm the amount of organic component (basic functional group) per each pore. of can be used as an index, if such value is 0.06 / nm or more, in order to sufficiently improve the performance of adsorbing CO _2, is a high affinity basic functional group and CO ₂ It can be judged that it is introduced at a sufficient rate.

Further, the value of the organic component ratio ([mass ratio of organic components] / [average pore diameter of sample]) per such average pore diameter is preferably 0.07 to 0.2 / nm, More preferably, it is 0.07 to 0.15 / nm. When the organic component ratio per such average pore diameter is within the above range, amino groups are more sufficiently dispersed in the pores, and CO ₂ tends to be more sufficiently adsorbed. In addition, when the organic component ratio per such average pore diameter exceeds the upper limit, the pores are reduced and the CO ₂ adsorption amount tends to decrease.

Moreover, as such an organic silica-based porous body, from the viewpoint of easier preparation, trialkoxysilane containing a basic functional group represented by the general formula (2) (basic functional group-containing trioxide). More preferred is a condensate (copolymer) of (alkoxysilane) and tetraalkoxylane. Such a basic functional group-containing trialkoxysilane and tetraalkoxylane will be described later (will be described in more detail when a suitable method for producing a CO ₂ adsorbent is described).

In addition, the shape of such an organic silica-based porous body is not particularly limited, but is preferably powdered because it is easier to prepare an organic silica-based porous body that satisfies the above conditions. Moreover, when an organic silica type porous body is a powder form, it is preferable that an average particle diameter is 0.1-2 micrometers, and it is more preferable that it is 0.2-1 micrometer. Such an average particle diameter of agglomerated particles is less than the lower limit, there is a tendency that moldability is lowered, while the pores inside the particles exceeds the upper limit will not be able to contribute to the adsorption of CO _2, CO ₂ The amount of adsorbed tends to decrease. The particles constituting the powder herein may be so-called spherical particles or substantially spherical particles having a minimum diameter of 10% or more (preferably 20% or more) of the maximum diameter. When the particles are substantially spherical, the particle size is an average value of the minimum diameter and the maximum diameter in principle.

Further, the CO ₂ adsorbent of the present invention is not particularly limited as long as it is composed of the organic silica-based porous body. For example, the powdered organic silica-based porous body is directly used as the CO ₂ adsorbent. Alternatively, it may be used by being supported on various base materials (for example, an aluminum honeycomb). Thus, the form of the CO ₂ adsorbent of the present invention can be changed as appropriate according to the intended use. Moreover, when an organic silica type porous body is a powder form, you may shape | mold and use as needed. Such a molding means is not particularly limited, and known molding means such as extrusion molding, tablet molding, CIP and the like can be appropriately used so as to obtain an optimum shape according to the application.

Although the CO ₂ adsorbent of the present invention has been described above, a method suitable for producing the CO ₂ adsorbent of the present invention will be described below.

A suitable method for producing the CO ₂ adsorbent of the present invention is not particularly limited. For example, a silica raw material and a surfactant are mixed in a solvent, and the surfactant is introduced into the pores. A first step of obtaining a porous body precursor,
A second step of obtaining a CO ₂ adsorbent comprising an organic silica based porous material by removing the surfactant contained in the porous material precursor,
As the silica raw material, the following general formula (2):
R ¹ —NH— (CH ₂ ) _n —Si (OR ² ) ₃ (2)
[Wherein, R ¹ represents any one selected from the group consisting of a hydrogen atom, an aminoalkyl group and an aminoalkylaminoalkyl group, n represents an integer of 1 to 6, and R ² represents an alkyl group. ]
Using a mixture of a basic functional group-containing trialkoxysilane represented by
As the surfactant, the following general formula (3):
CH ₃ (CH ₂ ) _m N ⁺ (CH ₃ ) _3. Y ^- (3)
[Wherein, m represents an integer of 8 to 25, and Y represents a halogen atom. ]
An alkyltrimethylammonium halide represented by:
It is a method for obtaining the CO ₂ adsorbent of the present invention as the CO ₂ adsorbent by adjusting the content ratio of the basic functional group-containing trialkoxysilane and the tetraalkoxylane in the silica raw material. preferable. Hereinafter, such a method will be described separately for each process.

<First step>
The first step is a step of obtaining a porous precursor obtained by mixing a silica raw material and a surfactant in a solvent and introducing the surfactant into the pores.

  As the solvent used in the first step, a known solvent that can be used in the production of the silica-based porous material can be appropriately used, and is not particularly limited. From the viewpoint of producing particles having a uniform diameter, it is preferable to use a mixed solvent of water and alcohol. Examples of such alcohol include methanol, ethanol, isopropanol, n-propanol, ethylene glycol, and glycerin, and methanol or ethanol is preferable from the viewpoint of solubility of the silica raw material. In addition, when the solvent is a mixture of water and alcohol (when the solvent is “water / alcohol mixed solvent”), the alcohol content in the water / alcohol mixed solvent is not particularly limited. More preferably, the amount is 10 to 90% by volume (more preferably 20 to 80% by volume). If the alcohol content is less than the lower limit, the particle size distribution is wide and particles having a large particle size tend to be obtained. On the other hand, if the upper limit is exceeded, the regularity of the pores tends to be significantly reduced. .

The silica raw material used in the first step is a mixture of the basic functional group-containing trialkoxysilane represented by the general formula (2) and tetraalkoxylane. With respect to such a basic functional group-containing trialkoxysilane (compound represented by the formula: R ¹ —NH— (CH ₂ ) _n —Si (OR ² ) ₃ ), R ¹ in the above general formula (2), n is the same as R ¹ and n in the general formula (1) described in the CO ₂ adsorbent of the present invention (preferable examples thereof are also the same). R ² in the general formula (2) is an alkyl group. Such an alkyl group that can be selected as R ² is preferably independently an alkyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 to 2 carbon atoms. If the number of carbon atoms exceeds the upper limit, the solubility and reactivity in the solvent are lowered, the particle diameter is increased, and the regularity of the pores tends to be lowered. Moreover, as such an alkyl group, a methyl group and an ethyl group are more preferable, and a methyl group is particularly preferable.

  Examples of such a basic functional group-containing trialkoxysilane include aminopropyltrimethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminoethylaminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylaminopropyltriethoxy. Examples include silane and aminoethylaminoethylaminopropyltriethoxysilane. Such basic functional group-containing trialkoxysilanes may be used singly or in combination of two or more. However, when two or more types of basic functional group-containing trialkoxysilanes are used, the reaction conditions at the time of production may be complicated, so the basic functional group-containing trialkoxysilane should be used alone. Is preferred.

  Further, as the tetraalkoxysilane used as the silica raw material, a known one can be used as appropriate. Examples of such tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and dimethoxydiethoxysilane. Among such tetraalkoxysilanes, tetramethoxysilane and tetraethoxysilane are preferable, and tetramethoxysilane is particularly preferable from the viewpoint of reactivity. Such tetraalkoxysilanes may be used alone or in combination of two or more. However, when two or more kinds of tetraalkoxysilanes are used, it is preferable to use one kind of tetraalkoxysilane alone because the reaction conditions during the production may be complicated.

  Further, in the silica raw material (a mixture of the basic functional group-containing trialkoxysilane and the tetraalkoxysilane), the content ratio of the tetraalkoxylane and the basic functional group-containing trialkoxysilane is the specific organic content. In order to produce a silica-based porous body, the ratio needs to be appropriately changed according to the type of surfactant used. Such a content ratio will be described later.

The surfactant used in the first step is represented by the following general formula (3):
CH ₃ (CH ₂ ) _m N ⁺ (CH ₃ ) _3. Y ^- (3)
[Wherein, m represents an integer of 8 to 25, and Y represents a halogen atom. ]
It is alkyltrimethylammonium halide represented by these.

  Such an alkyltrimethylammonium halide is excellent in the symmetry of the surfactant molecule. Therefore, when the alkyltrimethylammonium halide is used, the surfactants can be easily aggregated (formation of micelles, etc.).

  Moreover, m in the said General formula (1) shows the integer of 8-25, It is more preferable that it is an integer of 8-17, It is especially preferable that it is an integer of 9-15. The alkyltrimethylammonium halide having m of 7 or less tends to make it impossible to obtain a porous material because micelle formation is insufficient. On the other hand, in the case of alkyltrimethylammonium halide having m of 26 or more, the hydrophobic interaction of the surfactant is too strong, so that a layered compound is generated and a porous body tends not to be obtained.

  Furthermore, Y in the general formula (3) represents a halogen atom, and the kind of such a halogen atom is not particularly limited, but Y is preferably a chlorine atom or a bromine atom from the viewpoint of easy availability.

The surfactant represented by the general formula (3) is specifically an alkyltrimethylammonium halide having a long chain alkyl group having 9 to 26 carbon atoms, such as nonyltrimethylammonium halide, decyltrimethyl. Examples include ammonium halide, dodecyltrimethylammonium halide, tetradecyltrimethylammonium halide, hexadecyltrimethylammonium halide, octadecyltrimethylammonium halide, eicosyltrimethylammonium halide, docosyltrimethylammonium halide, and the like. Such a surfactant is preferably used alone from the viewpoint of producing a CO ₂ adsorbent more efficiently.

The content of in the first step, in order to obtain a CO ₂ adsorbent of the present invention as the CO ₂ adsorbent, and the basic functional group-containing trialkoxysilane of the silica in the feed and the tetraalkoxysilane Adjust the ratio. The content ratio of such a basic functional group-containing trialkoxysilane and the tetraalkoxylane depends on the type of the alkyltrimethylammonium halide (surfactant) and the type of the basic functional group-containing trialkoxysilane used. Therefore, it is necessary to adjust appropriately so as to achieve the target design, and it cannot be generally said.

The content ratio between such a basic functional group-containing trialkoxysilane and the tetraalkoxylane cannot be generally described as described above, but the value of m in the above general formula (3) is used as the surfactant. In the case where the alkyltrimethylammonium halide (more preferably decyltrimethylammonium halide) is 8 to 12, for example, R ¹ in the general formula (2) is used as the basic functional group-containing trialkoxysilane. When a basic functional group-containing trialkoxysilane that is a hydrogen atom is used, the content ratio (mol%) is 15 to 35 mol based on the total amount of the basic functional group-containing trialkoxysilane and tetraalkoxylane. % Of the basic functional group-containing trialkoxysilane as the general formula (2 ) In which a basic functional group-containing trialkoxysilane in which R ¹ is an aminoalkyl group (more preferably an aminoethyl group) is used, the content ratio (mol%) is determined based on the basic functional group-containing trialkoxysilane. It is preferable to adjust in the range of 15 to 35 mol% with respect to the total amount of alkenyl and tetraalkoxylane, and R ¹ in the general formula (2) is aminoalkyl as the basic functional group-containing trialkoxysilane. When a basic functional group-containing trialkoxysilane which is an aminoalkyl group (more preferably aminoethylaminoethyl group) is used, the content ratio (mol%) is determined between the basic functional group-containing trialkoxysilane and tetraalkoxysilane. It is preferable to adjust to the range of 5-25 mol% with respect to the total amount.

Moreover, regarding the content ratio of such a basic functional group-containing trialkoxysilane and the tetraalkoxylane, the alkyltrimethylammonium having a value of m in the general formula (3) of 13 to 25 as the surfactant. In the case of using a halide (more preferably hexadecyltrimethylammonium halide), for example, the basic functional group-containing trialkoxysilane contains a basic functional group in which R ¹ in the general formula (2) is a hydrogen atom In the case of trialkoxysilane, the content ratio (mol%) is preferably adjusted to a range of 22 to 48 mol% with respect to the total amount of the basic functional group-containing trialkoxysilane and tetraalkoxylane. , R ¹ is an aminoalkyl group of the basic functional group-containing trialkoxysilane is the general formula (2) When a basic functional group-containing trialkoxysilane that is more preferably an aminoethyl group is used, the content ratio (mol%) is based on the total amount of the basic functional group-containing trialkoxysilane and tetraalkoxysilane. Te is preferably adjusted to a range of 22 to 48 mol%, further, the basic functional group-containing trialkoxysilane is formula (2) R ¹ is an amino alkyl amino alkyl group (more preferably aminoethylamino in When using a basic functional group-containing trialkoxysilane that is an ethyl group), the content ratio (mol%) is 12 to 38 with respect to the total amount of the basic functional group-containing trialkoxysilane and tetraalkoxysilane. It is preferable to adjust to the range of mol%.

  Furthermore, in the present invention, when the silica raw material and the surfactant are mixed in the solvent, the concentration of the silica raw material is 0.0005 to 0.1 mol / L based on the total volume of the solution in terms of Si concentration. (Preferably 0.003-0.05 mol / L). If the concentration of the silica raw material is less than the lower limit, it tends to be difficult to control the particle diameter and the particle size distribution. On the other hand, if the upper limit is exceeded, the amount of the silica raw material in the solvent becomes excessive. There is a tendency that a good porous body cannot be obtained because the ratio of the surfactant to be the pore template is insufficient.

  In addition, when the silica raw material and the surfactant are mixed in the solvent, the concentration of the surfactant is 0.0003 to 0.3 mol / L (preferably 0.0005 to 0.55 mol) based on the total volume of the solution. 0.15 mol / L) is preferable. If the concentration of such a surfactant is less than the above lower limit, the ratio of the surfactant to be a pore template (template) is insufficient, so that it is difficult to obtain a good porous body. When the upper limit is exceeded, when obtaining a powdery porous material, it is difficult to control the particle size and particle size distribution, and the uniformity of the particle size of the resulting organic silica-based porous material tends to be low.

  Furthermore, when mixing the silica raw material and the surfactant in the solvent, the content ratio of the silica raw material and the surfactant is the molar amount in terms of Si concentration in the silica raw material (silica raw material Si concentration equivalent). Molar ratio) to the molar amount of the surfactant ([mol amount in terms of silica raw material Si concentration]: [molar amount of surfactant]): 1:10 to 20: 1 (more preferably 1: 5). To 10: 1). When the molar amount of the surfactant is less than the lower limit, the formation of pores tends to be incomplete. On the other hand, when the upper limit is exceeded, nanoparticles coated with the surfactant tend to be formed. .

  In the first step, the silica raw material and the surfactant are mixed in a solvent. At this time, it is preferable to mix under basic conditions. Silica raw materials generally react under both basic and acidic conditions and change to silicon oxide. However, the reaction of silicon atoms is more effective when reacted under basic conditions than when reacted under acidic conditions. Since the number of points tends to increase and a silicon oxide having excellent physical properties such as moisture resistance and heat resistance tends to be obtained, mixing under basic conditions is advantageous in this respect. From such a viewpoint, in the first step, it is preferable to add a basic substance such as sodium hydroxide to the solvent in order to make the solvent basic. The basic condition of such a solvent is not particularly limited, but the value obtained by dividing the alkali equivalent of the basic substance to be added by the number of moles of silicon atoms in the total silica raw material is 0.1 to 0.9. It is preferable that the ratio is 0.2 to 0.5. When the value obtained by dividing the alkali equivalent of the basic substance to be added by the number of moles of silicon atoms in the total silica raw material is less than 0.1, the yield tends to decrease, and on the other hand, it exceeds 0.9. In such a case, the formation of the porous body tends to be difficult.

In addition, by such mixing, a silanol group is produced from each alkoxysilane as a silica raw material by hydrolysis, and the resulting silanol groups are condensed to form a silicon oxide. Therefore, the silicon oxide formed is derived from the basic functional group-containing trialkoxysilane in the silica raw material and represented by a basic functional group (formula: R ¹ —NH— (CH ₂ ) _n —). Group) will be introduced. That is, a silicon oxide having a structure in which the basic functional group is bonded to silicon in the skeleton (structure represented by the formula: R ¹ —NH— (CH ₂ ) _n —Si) is obtained. Further, in the condensation reaction in which such silicon oxide is formed, pores are formed in the portion where the surfactant is present. Thus, the surfactant is introduced into silicon oxide (condensate of silica raw material) and functions as a template for pore formation. In this way, in the first step, a porous precursor obtained by introducing the surfactant into the pores (silica (silicon oxide in which the surfactant is introduced into the portion where the pores are formed). ) Is formed.

  The reaction conditions (reaction temperature, reaction time, etc.) of the condensation reaction in the first step are not particularly limited, and the reaction temperature is, for example, −20 ° C. to 100 ° C. (preferably 0 ° C. to 80 ° C., more Preferably, it can be set to 10 ° C to 40 ° C. In addition, the reaction is preferably allowed to proceed with stirring. Specific reaction conditions are preferably determined based on the type of silica raw material used.

  In such a first step, for example, a porous precursor can be obtained as follows. First, a basic solution containing the surfactant is prepared by adding the surfactant and basic substance to a mixed solvent of water and alcohol, and the silica raw material is added to the obtained basic solution. To do. Since the silica raw material thus added is hydrolyzed (or hydrolyzed and condensed) in the solution, a precipitate (white powder) is deposited after a while after the addition. After such a precipitate (white powder) is deposited, the solution is further stirred at 0 ° C. to 80 ° C. (preferably 10 ° C. to 40 ° C.) for 1 hour to 10 days to react the silica raw material. By proceeding, it is possible to obtain a powdery porous precursor (a porous precursor (silica-based porous precursor) in which the surfactant is introduced at a site where pores are formed).

  In the first step, after completion of the reaction, the obtained porous precursor may be filtered and washed as necessary. For example, in the case of obtaining a powdery porous precursor as described above, washing is performed by dispersing a solid content obtained by filtering the obtained precipitate (white powder) in a large amount of water, It may be filtered again and dried. In this way, the porous body precursor can be obtained in the first step.

  In addition, the shape of the porous body precursor prepared in this way is not particularly limited, and may be various shapes such as a thin film in addition to the powder shape described above. In addition, when manufacturing a thin film-like porous body precursor in this way, it is preferable to employ | adopt the following methods as a 1st process, for example. That is, first, the silane raw material is added to an acidic solution obtained by adding an acid (for example, hydrochloric acid, nitric acid, etc.) to a solution containing the solvent and the surfactant, and this solution is stirred to react (partial). Hydrolysis and partial condensation reaction) to produce a sol solution containing the partial polymer. In addition, since the hydrolysis reaction of the silane raw material is likely to occur in a low pH region, partial polymerization can be promoted by lowering the pH of the system. Therefore, the pH of the acidic solution is preferably 6 or less, and more preferably 4 or less. The reaction temperature is preferably about 15 to 25 ° C., and the reaction time is preferably about 30 minutes to 1 day. Next, a thin film-like porous body precursor can be prepared by applying the sol solution thus obtained to a substrate. There is no restriction | limiting in particular as a method of apply | coating the said sol solution to a board | substrate, Various coating methods can be employ | adopted suitably. Examples of the method include a solution casting method, a coating method using a bar coater, a roll coater, a gravure coater, and the like, a method such as dip coating, spin coating, and spray coating. It is also possible to form a patterned porous precursor on the substrate by applying a sol solution by an ink jet method.

<Second step>
The second step is a step of obtaining a CO ₂ adsorbent comprising an organic silica-based porous material by removing the surfactant contained in the porous material precursor.

  The method for removing the surfactant contained in the porous precursor is not particularly limited, and a known method can be appropriately employed. Examples thereof include a method of treating with an organic solvent and an ion exchange method. . When adopting the method of treating with the organic solvent as a method of removing the surfactant, a method of extracting the surfactant by immersing the porous precursor in a good solvent having high solubility in the used surfactant Is preferably adopted. When the ion exchange method is adopted as a method for removing the surfactant, the porous body precursor is immersed in an acidic solution (such as ethanol containing a small amount of hydrochloric acid) and heated at, for example, 50 to 70 ° C. It is possible to employ a method in which stirring is carried out while performing. Thereby, the surfactant present in the pores of the porous precursor is ion-exchanged with hydrogen ions. In addition, although hydrogen ions remain in the hole by ion exchange, the problem of blockage of the hole does not occur because the ion radius of the hydrogen ion is sufficiently small. In addition, after ion exchange with an acidic solution in this way, the porous body after ion exchange is immersed in a basic solution (such as methanol containing a small amount of concentrated aqueous ammonia solution), for example, 10 to 60 ° C. ( It is preferable to stir at preferably room temperature. As described above, by stirring the porous body after ion exchange in a basic solution (such as methanol containing a small amount of concentrated aqueous ammonia solution), it is possible to convert the hydrochloride of an amino group into an amino group.

By removing the surfactant in this manner, an organic silica-based porous body having a structure represented by the above general formula (1) in which a basic functional group is bonded to silicon in the skeleton of the porous body. The specific surface area of the porous body (specific surface area determined based on the nitrogen adsorption isotherm of the organic silica-based porous body) is 1 to 30 m ² / g, and the mass ratio of the organic components in the porous body Is obtained by dividing the porous body by the average pore diameter of the sample obtained based on the nitrogen adsorption isotherm of the sample obtained by heat-treating the porous body at 550 ° C. for 6 hours ([mass ratio of organic components] / [Average pore diameter of the sample]) is 0.06 / nm or more, an organic silica-based porous material can be obtained. The organosilica-based porous material prepared in this way is the same as that described in the CO ₂ adsorbent of the present invention. That is, by preparing the organic silica-based porous material in this way, the CO ₂ adsorbent of the present invention can be obtained efficiently.

The use of the CO ₂ adsorbent of the present invention is not particularly limited. For example, exhaust gas from a power plant (the content ratio of CO _{2 in} the exhaust gas is generally about CO ₂ : 15 to 16% by volume) The exhaust gas temperature is generally about 50 to 75 ° C., the pressure is about 100 kPa (1 Bar), and the exhaust gas from the automobile (the content ratio of CO _{2 in} the gas is generally about CO ₂ : 10% by volume) There, the exhaust gas temperature is generally about 70 to 90 ° C., the pressure can be mentioned applications such as CO ₂ adsorbent for separating by adsorption of CO ₂ in the range of about 100 kPa).

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
First, 3.52 g (0.011 mol) of hexadecyltrimethylammonium chloride (surfactant) and 2.28 mL of 1N sodium hydroxide solution were added to a mixed solution consisting of 397.7 g of water and 400 g of methanol. To obtain a mixed solution (a step of obtaining a mixed solution). Next, a silane raw material composed of 9.2 g (0.0604 mol) of tetramethoxysilane and 4.7 g (0.0262 mol) of aminopropyltrimethoxysilane is added to the obtained mixed solution, and the reaction solution is added. Got. When such a silane raw material was added, it was confirmed that the reaction solution became cloudy after a while and particles were synthesized. Subsequently, after stirring the said reaction liquid at room temperature (25 degreeC) for 8 hours, solid content in the reaction liquid after stirring was collect | recovered by filtration. The solid content (residue after filtration) thus obtained is redispersed in 1 L of water to obtain a dispersion, and then the solid content (residue after filtration) is recovered again by filtration, and the obtained solid content is obtained. The (residue) was dried in an oven at 45 ° C. to obtain a powdery porous body precursor (dry powder: silica / surfactant composite).

  A dispersion obtained by dispersing 10 g of the powdered porous precursor (dry powder) thus obtained in 1 L of an acidic solution composed of 10 mL of concentrated hydrochloric acid (concentration: 36.8% by mass) and ethanol (remainder). Then, the dispersion was stirred at 60 ° C. for 3 hours to remove hexadecyltrimethylammonium from the powdery porous precursor. Subsequently, solid content was collect | recovered by filtration from the said dispersion liquid, and the obtained solid content was dried in 45 degreeC oven. Next, 3.5 g of the solid content after drying was dispersed in 200 mL of a basic solution composed of 10 mL of concentrated aqueous ammonia (concentration: 28% by mass) and methanol (remainder) to obtain a dispersion. Stir at room temperature (25 ° C.) for 8 hours. Then, solid content was collect | recovered by filtration from the dispersion liquid after the said stirring, and the organic silica type porous body was obtained by drying the obtained solid content in 45 degreeC oven.

<Measurement of specific surface area of organosilica-based porous material>
The specific surface area of the organic silica based porous material was measured as follows. That is, first, 50 mg of the organic silica-based porous material was heat-treated at 80 ° C. for 2 hours under vacuum conditions (1 Pa or less), and a sample for measurement of the organic silica-based porous material (dried organic silica-based material) A porous body) was prepared. Next, using the obtained sample for measurement, using a product name “Autosorb-1” manufactured by Quantachrome as a measuring device, a gas adsorption method (adopting a constant volume method) at a liquid nitrogen temperature (−196 ° C.) The nitrogen adsorption isotherm of the organosilica-based porous material was determined by determining the nitrogen gas adsorption amount by gradually increasing the nitrogen gas pressure introduced and plotting the nitrogen gas adsorption amount for each equilibrium pressure. . Next, the specific surface area of the organic silica-based porous material was determined by calculating by the BET method using the nitrogen adsorption isotherm of the organic silica-based porous material.

As a result of such measurement, it was confirmed that the porous body obtained in Example 1 had a specific surface area (BET) of 8.2 m ² / g.

<Measurement of average pore diameter of sample>
First, 100 mg of the organosilica-based porous material was heat-treated at 550 ° C. for 6 hours to prepare a sample. Then, using 50 mg of the sample, the product name “Autosorb-1” manufactured by Quantachrome was used as a measuring device, and the nitrogen gas was absorbed by a gas adsorption method (adopting a constant volume method) at a liquid nitrogen temperature (−196 ° C.). The adsorption amount was determined, and the nitrogen adsorption isotherm of the sample was determined by gradually increasing the pressure of the introduced nitrogen gas and plotting the adsorption amount of the nitrogen gas against each equilibrium pressure. And the specific surface area (S) of the said sample was calculated | required by calculating by BET method using the nitrogen adsorption isotherm of this sample (baking goods). Next, by using the nitrogen adsorption isotherm of the sample, the nitrogen adsorption amount at P / P ₀ (relative pressure) = 0.95 was converted to the standard state to obtain the nitrogen gas adsorption capacity. The specific surface area of the sample calculated by the BET method using the value of the nitrogen gas adsorption capacity as the pore volume (V) of the sample and using the nitrogen adsorption isotherm of the sample (baked product) Using (S), the following formula:
D = 4V / S
[In the formula, D represents the average pore diameter (average pore diameter) of the sample, V represents the pore volume (total pore volume) of the sample, and S represents the specific surface area of the sample. ]
Was calculated to obtain the average pore diameter (D) of the sample.

  As a result of such calculation, the average pore diameter (average pore diameter) of the sample after baking of the porous body obtained in Example 1 (baked product heat-treated at 550 ° C. for 6 hours) was 2.18 nm. .

<Measurement of mass ratio of organic components in porous body>
The mass ratio of the organic components of the organic silica-based porous body (organic component ratio: content ratio based on mass of the organic components in the porous body) was measured as follows. That is, first, 10 mg of an organic silica-based porous material is used as a measurement sample, and a thermogravimetry apparatus (a thermogravimetric analyzer manufactured by Rigaku Corporation: trade name “Thermo Plus”) is used as a measurement apparatus. A thermogravimetric curve was measured in the temperature range from room temperature (25 ° C) to 800 ° C at a rate of temperature increase of ° C / min, and the weight fraction at 150 ° C from the thermogravimetric curve (W1: residual weight at 150 ° C) Rate, unit: wt%) and weight fraction at 600 ° C. (W2: residual fraction of weight at 600 ° C., unit: wt%), and the following calculation formula (I):
[Mass ratio of organic components] = (W1-W2) / W1 (I)
(In formula (I), W1 represents the weight fraction at 150 ° C. in the thermogravimetric curve, and W2 represents the weight fraction at 600 ° C. in the thermogravimetric curve.)
Was calculated to obtain the mass ratio (organic component ratio) of the organic components.

  As a result of such measurement, it was confirmed that the mass ratio of the organic component in the organic silica-based porous material (Example 1) was 0.216 (21.6 mass%). Further, from the value of the mass ratio of the organic component thus obtained and the measurement result of the average pore diameter (average pore diameter) of the sample, the mass ratio of the organic component in the porous body is determined as the average of the sample. By dividing by the pore diameter, the value of the organic component ratio per average pore diameter (mass ratio of organic components per average pore diameter: [mass ratio of organic components] / [average pore diameter of sample]) was obtained. , 0.099 / nm was confirmed.

<NMR measurement>
Si-NMR measurement was performed on the organosilica porous body using a trade name “AVANCE 400” manufactured by Hitachi High-Technologies Corporation as a measuring device.

  From the NMR measurement results, a peak was confirmed in the vicinity of -70 ppm in the graph of the Si-NMR spectrum. Here, such a peak in the vicinity of -70 ppm is based on the Si-C bond. From these results and the type of silica raw material used, it is clear that the Si—C bond confirmed in the graph of the Si-NMR spectrum is a bond between silicon and an aminopropyl group, and the organic silica-based porous material (Example 1) was confirmed to have a structure in which an aminopropyl group (basic functional group) is bonded to silicon (Si).

<Measurement of CO ₂ adsorption isotherm>
100 mg of the organic silica-based porous material was used for each test, and BELSORP-MAX-12-N-T-HL manufactured by Microtrack Bell was used as a measuring device at each temperature of 0 ° C., 40 ° C., 60 ° C., and 80 ° C. , CO ₂ adsorption isotherms were measured respectively. The obtained results are shown in FIG.

As is clear from the results shown in FIG. 1, the organic silica-based porous material obtained in Example 1 has a 0 ° C. CO ₂ adsorption isotherm and a temperature range of 40 ° C. or higher (40 ° C., 60 ° C. , comparing the CO ₂ adsorption isotherms of 80 temperature range ° C.), the temperature is in the temperature range of not lower than 40 ° C., the adsorption amount of CO ₂ was increased.

Further, as is apparent from the results shown in FIG. 1, the organic silica porous material obtained in Example 1 is CO _{2 in} a high temperature range of 60 ° C. or higher (temperature range of 60 ° C. and 80 ° C.). When the pressure (partial pressure) of CO ₂ is 15 kPa (assuming an approximate partial pressure of CO ₂ in the exhaust gas from the power plant), the adsorption amount of CO ₂ is 12 cm ³ (STP) / g or more, It was found that the adsorption amount of CO ₂ was sufficiently high in the high temperature range.

Here, the pressure of CO ₂ (partial pressure) is assumed when adsorbing CO ₂ in the flue gas is 15 kPa, 0 ° C. the adsorption amount ^{3cm 3 (STP) / g,} 60 adsorption at ° C. 13. ^{8cm 3 (STP) / g,} 80 adsorption at ℃ was found to be 12cm ³ (STP) / g. From these results, the organosilica-based porous material obtained in Example 1 is, for example, exhaust gas from a power plant (generally, the content ratio of CO ₂ is about 15 to 16% by volume, and the exhaust gas temperature is 50 to 75%. It has been found to be particularly effective for adsorption of CO ₂ in the order of 100 ° C. and pressure of about 100 kPa (1 Bar).

(Example 2)
Instead of using a silane raw material consisting of 9.2 g (0.0604 mol) of tetramethoxysilane and 4.7 g (0.0262 mol) of aminopropyltrimethoxysilane, 9.2 g (0.0604 mol) of tetramethoxysilane and An organic silica-based porous material was obtained in the same manner as in Example 1 except that a silane raw material composed of 5.8 g (0.026 mol) of aminoethylaminopropyltrimethoxysilane was used.

With respect to the organic silica porous material thus obtained (Example 2), the specific surface area of the organic silica porous material, the average pore diameter (average pore diameter) of the sample, and the mass ratio of the organic components in the porous material And the Si-NMR chart was measured by adopting the same method as the measurement method employed in Example 1. As a result of such measurement, the organosilica porous body (Example 2) has a specific surface area of 16.9 m ² / g, and the sample obtained by calculation (the porous body at 550 ° C. for 6 hours). The average pore diameter (average pore diameter) of the heat-treated sample (fired product) was 2.3 nm. The organic silica-based porous body (Example 2) has an organic component mass ratio of 0.257 (25.7 mass%), and an organic component ratio per average pore diameter (organic component per average pore diameter). Mass ratio: [mass ratio of organic components] / [average pore diameter of sample]) was confirmed to be 0.112 / nm. Furthermore, from the graph of the measured Si-NMR spectrum, the organosilica porous body (Example 2) has a structure in which an aminoethylaminopropyl group (basic functional group) is bonded to silicon (Si). It was confirmed that there was.

<Measurement of CO ₂ adsorption isotherm>
100 mg of the organosilica-based porous material (Example 2) was used for each test, and BELSORP-MAX-12-N-T-HL manufactured by Microtrack Bell was used as a measuring device, and 0 ° C., 40 ° C., 60 ° C., 80 The CO ₂ adsorption isotherm was measured at each temperature of ° C and 100 ° C. The obtained results are shown in FIG.

As is clear from the results shown in FIG. 2, the organic silica-based porous material obtained in Example 2 has a CO ₂ adsorption isotherm of 0 ° C. and a temperature range of 40 ° C. or higher (40 ° C., 60 ° C. , 80 ° C., 100 ° C.) CO ₂ adsorption isotherm, the amount of CO ₂ adsorption increased in the temperature range of 40 ° C. or higher. Further, as is clear from the results shown in FIG. 2, the organic silica porous material obtained in Example 2 is in a high temperature range of 60 ° C. or higher (temperature range of 60 ° C., 80 ° C., 100 ° C.). , the amount of adsorption of CO ₂ when the pressure of CO ₂ (partial pressure) is 15 kPa (assuming an approximate partial pressure of CO ₂ in the flue gas from power plants) of 10.6cm ³ (STP) / g or more It was found that the amount of CO ₂ adsorbed was sufficiently high in a high temperature range (more preferably 60 to 100 ° C.).

Here, from the results shown in FIG. 2, the resulting organic silica-based porous body in Example 2, the pressure of CO ₂ (partial pressure) is assumed when adsorbing CO ₂ in the flue gas is 15 kPa, 0 In adsorption amount at ° C. is ^{2.7cm 3 (STP) / g,} 40 ℃ the amount of adsorption ^{6.8cm 3 (STP) / g,} 60 adsorption at ° C. is ^{11.8cm 3 (STP) / g,} 80 ℃ It was found that the adsorption amount was 13.2 cm ³ (STP) / g, and at 100 ° C., the adsorption amount was 10.6 cm ³ (STP) / g. From these results, the organosilica-based porous material obtained in Example 2 is, for example, exhaust gas from a power plant (generally, the content ratio of CO ₂ is about 15 to 16% by volume, and the exhaust gas temperature is 50 to 75%. It has been found to be particularly effective for adsorption of CO ₂ in the order of 100 ° C. and pressure of about 100 kPa (1 Bar).

(Example 3)
Instead of using a silane raw material consisting of 9.2 g (0.0604 mol) of tetramethoxysilane and 4.7 g (0.0262 mol) of aminopropyltrimethoxysilane, 10.6 g (0.0696 mol) of tetramethoxysilane and An organic silica-based porous material was obtained in the same manner as in Example 1 except that a silane raw material consisting of 4.6 g (0.0173 mol) of aminoethylaminoethylaminopropyltrimethoxysilane was used.

With respect to the organic silica porous material thus obtained (Example 3), the specific surface area of the organic silica porous material, the average pore diameter of the sample (average pore diameter), and the mass ratio of the organic components in the porous material And the Si-NMR chart was measured by adopting the same method as the measurement method employed in Example 1. As a result of such measurement, the organic silica-based porous material (Example 3) has a specific surface area of 13.7 m ² / g, and the sample obtained by calculation (the porous material is heated at 550 ° C. for 6 hours). The average pore diameter (average pore diameter) of the heat-treated sample (fired product) was 2.3 nm. The organic silica-based porous material (Example 3) has an organic component mass ratio of 0.267 (26.7% by mass), and an organic component ratio per average pore size (organic component per average pore size). Mass ratio: [mass ratio of organic components] / [average pore diameter of sample]) was confirmed to be 0.116 / nm. Furthermore, from the graph of the measured Si-NMR spectrum, the organic silica-based porous material (Example 3) has a structure in which aminoethylaminoethylaminopropyl group (basic functional group) is bonded to silicon (Si). It was confirmed to be a thing.

<Measurement of CO ₂ adsorption isotherm>
100 mg of the organosilica-based porous material (Example 3) was used for each test, and BELSORP-MAX-12-N-T-HL manufactured by Microtrack Bell was used as a measuring device, and 0 ° C., 40 ° C., 60 ° C., 80 The CO ₂ adsorption isotherm was measured at each temperature of ° C and 100 ° C. The obtained results are shown in FIG.

As is clear from the results shown in FIG. 3, the organic silica-based porous material obtained in Example 3 has a CO ₂ adsorption isotherm of 0 ° C. and a temperature range of 40 ° C. or higher (40 ° C., 60 ° C. , 80 ° C., 100 ° C.) CO ₂ adsorption isotherm, the amount of CO ₂ adsorption increased in the temperature range of 40 ° C. or higher. Further, as is clear from the results shown in FIG. 3, the organic silica-based porous material obtained in Example 3 is in a high temperature range of 60 ° C. or higher (temperature range of 60 ° C., 80 ° C., 100 ° C.). , the amount of adsorption of CO ₂ when the pressure of CO ₂ (partial pressure) is 15 kPa (assuming an approximate partial pressure of CO ₂ in the flue gas from power plants) of 7.6cm ³ (STP) / g or more It was found that the amount of CO ₂ adsorbed was sufficiently high in the high temperature range.

Here, from the results shown in FIG. 3, the resulting organic silica-based porous body in Example 3, the pressure of CO ₂ (partial pressure) is assumed when adsorbing CO ₂ in the flue gas is 15 kPa, 0 ℃, adsorption amount ^{3cm 3 (STP) / g,} 40 ℃ the amount of adsorption ^{4.4cm 3 (STP) / g,} 60 adsorption at ° C. is 7.6cm ³ (STP) / g, at 80 ° C. adsorption Was 8.9 cm ³ (STP) / g, and at 100 ° C., the adsorption amount was 7.6 cm ³ (STP) / g. From these results, the organosilica-based porous material obtained in Example 3 is, for example, exhaust gas from a power plant (generally, the content ratio of CO ₂ is about 15 to 16% by volume, and the exhaust gas temperature is 50 to 75%. It has been found to be particularly effective for adsorption of CO ₂ in the order of 100 ° C. and pressure of about 100 kPa (1 Bar).

(Example 4)
Instead of using a silane raw material consisting of 9.2 g (0.0604 mol) of tetramethoxysilane and 4.7 g (0.0262 mol) of aminopropyltrimethoxysilane, 7.9 g (0.0519 mol) of tetramethoxysilane and An organic silica-based porous material was obtained in the same manner as in Example 1 except that a silane raw material consisting of 7.7 g (0.0346 mol) of aminoethylaminopropyltrimethoxysilane was used.

With respect to the organic silica porous body thus obtained (Example 4), the specific surface area of the organic silica porous body, the average pore diameter of the sample (average pore diameter), and the mass ratio of the organic components in the porous body And the Si-NMR chart was measured by adopting the same method as the measurement method employed in Example 1. As a result of such measurement, the organosilica porous body (Example 4) has a specific surface area of 15.9 m ² / g, and the sample obtained by calculation (the porous body at 550 ° C. for 6 hours). The average pore diameter (average pore diameter) of the heat-treated sample (fired product) was 2.3 nm. The organic silica based porous material (Example 4) has an organic component mass ratio of 0.268 (26.8% by mass), and an organic component ratio per average pore size (organic component per average pore size). Mass ratio: [mass ratio of organic components] / [average pore diameter of sample]) was confirmed to be 0.117 / nm. Furthermore, from the graph of the measured Si-NMR spectrum, the organosilica porous body (Example 4) has a structure in which an aminoethylaminopropyl group (basic functional group) is bonded to silicon (Si). It was confirmed that there was.

<Measurement of CO ₂ adsorption isotherm>
For each test, 100 mg of the organic silica-based porous material (Example 4) was used, and BELSORP-MAX-12-N-T-HL manufactured by Microtrac Bell was used as a measuring device, at 60 ° C., 80 ° C., 100 ° C., 120 The CO ₂ adsorption isotherm was measured at each temperature of ° C. The obtained results are shown in FIG.

As apparent from the results shown in FIG. 4, the organic silica-based porous material obtained in Example 4 is CO _{2 in} a high temperature range (60 ° C., 80 ° C., 100 ° C., 120 ° C. temperature range). If the pressure of the (partial pressure) is 15kPa become adsorption amount of CO ₂ (assuming an approximate partial pressure of CO ₂ in the flue gas from power plants) of 9.3 cm ³ (STP) / g or more Thus, it has been found that the adsorption amount of CO ₂ is sufficiently high in a high temperature range (more preferably, a temperature range of 60 to 100 ° C.).

Here, from the results shown in FIG. 4, the resulting organic silica-based porous body in Example 4, the pressure of CO ₂ (partial pressure) is assumed when adsorbing CO ₂ in the flue gas is 15 kPa, 60 The adsorption amount is 12.3 cm ³ (STP) / g at 80 ° C., the adsorption amount is 14 cm ³ (STP) / g at 80 ° C., the adsorption amount is 13.7 cm ³ (STP) / g at 100 ° C., and the adsorption amount at 120 ° C. Was found to be 9.3 cm ³ (STP) / g. From such results, the organic silica-based porous material obtained in Example 4 is, for example, exhaust gas from a power plant (generally, the content ratio of CO ₂ is about 15 to 16% by volume, and the exhaust gas temperature is 50 to 75%. It has been found to be particularly effective for adsorption of CO ₂ in the order of 100 ° C. and pressure of about 100 kPa (1 Bar).

(Example 5)
Instead of using a silane raw material consisting of 9.2 g (0.0604 mol) of tetramethoxysilane and 4.7 g (0.0262 mol) of aminopropyltrimethoxysilane, 9.2 g (0.0604 mol) of tetramethoxysilane and An organic silica-based porous material was obtained in the same manner as in Example 1 except that a silane raw material consisting of 6.9 g (0.026 mol) of aminoethylaminoethylaminopropyltrimethoxysilane was used.

With respect to the organic silica porous material thus obtained (Example 5), the specific surface area of the organic silica porous material, the average pore diameter of the sample (average pore diameter), and the mass ratio of the organic components in the porous material And the Si-NMR chart was measured by adopting the same method as the measurement method employed in Example 1. As a result of such measurement, the organosilica-based porous material (Example 5) has a specific surface area of 22.8 m ² / g, and the sample obtained by calculation (the porous material is heated at 550 ° C. for 6 hours). The average pore diameter (average pore diameter) of the heat-treated sample (baked product) was 2.5 nm. The organic silica based porous material (Example 5) has a mass ratio of organic components of 0.283 (28.3 mass%), and an organic component ratio per average pore size (organic components per average pore size). Mass ratio: [mass ratio of organic components] / [average pore diameter of sample]) was confirmed to be 0.113 / nm. Furthermore, from the graph of the measured Si-NMR spectrum, the organosilica porous body (Example 5) has a structure in which aminoethylaminoethylaminopropyl group (basic functional group) is bonded to silicon (Si). It was confirmed to be a thing.

<Measurement of CO ₂ adsorption isotherm>
For each test, 100 mg of the organosilica-based porous material (Example 5) was used, and BELSORP-MAX-12-N-T-HL manufactured by Microtrack Bell was used as a measuring device, at 60 ° C, 80 ° C, 100 ° C, 120 ° C. The CO ₂ adsorption isotherm was measured at each temperature of ° C. The obtained results are shown in FIG.

As is clear from the results shown in FIG. 5, the organic silica-based porous material obtained in Example 5 is CO _{2 in} a high temperature range (60 ° C., 80 ° C., 100 ° C., 120 ° C. temperature range). When the pressure (partial pressure) of CO ₂ is 15 kPa (assuming an approximate partial pressure of CO ₂ in the exhaust gas from the power plant), the amount of adsorption of CO ₂ becomes 6.8 cm ³ (STP) / g or more. Thus, it has been found that the adsorption amount of CO ₂ is sufficiently high in a high temperature range (more preferably, a temperature range of 60 to 100 ° C.).

Here, from the results shown in FIG. 5, the resulting organic silica-based porous body in Example 5, the pressure of CO ₂ (partial pressure) is assumed when adsorbing CO ₂ in the flue gas is 15 kPa, 60 In adsorption amount at ° C. is 8.2cm ³ (STP) / g, at 80 ° C. adsorption amount 9.8cm ³ (STP) / g, at 100 ° C. adsorption amount ^{9.7cm 3 (STP) / g,} 120 ℃ It was found that the amount of adsorption was 6.8 cm ³ (STP) / g. From these results, the organic silica porous material obtained in Example 5 is, for example, exhaust gas from a power plant (generally, the content ratio of CO ₂ is about 15 to 16% by volume, and the exhaust gas temperature is 50 to 75%. It has been found to be particularly effective for adsorption of CO ₂ in the order of 100 ° C. and pressure of about 100 kPa (1 Bar).

(Comparative Example 1)
Instead of using a silane raw material consisting of 9.2 g (0.0604 mol) of tetramethoxysilane and 4.7 g (0.0262 mol) of aminopropyltrimethoxysilane, 11.9 g (0.0782 mol) of tetramethoxysilane and An organic silica-based porous material was obtained in the same manner as in Example 1 except that a silane raw material composed of 1.6 g (0.0089 mol) of aminopropyltrimethoxysilane was used.

With respect to the organic silica porous material thus obtained (Comparative Example 1), the specific surface area of the organic silica porous material, the average pore diameter of the sample (average pore diameter), and the mass ratio of the organic components in the porous material And the Si-NMR chart was measured by adopting the same method as the measurement method employed in Example 1. As a result of such measurement, the organosilica porous body (Comparative Example 1) has a specific surface area of 850 m ² / g, and the sample obtained by calculation (the porous body is heated at 550 ° C. for 6 hours). Sample (baked product)) had an average pore diameter (average pore diameter) of 2.0 nm. The organic silica-based porous body (Comparative Example 1) has an organic component mass ratio of 0.108 (10.8 mass%), and an organic component ratio per average pore diameter (organic component per average pore diameter). Mass ratio: [mass ratio of organic components] / [average pore diameter of sample]) was confirmed to be 0.054 / nm. Furthermore, from the graph of the measured Si-NMR spectrum, the organosilica porous body (Comparative Example 1) has a structure in which an aminopropyl group (basic functional group) is bonded to silicon (Si). Was confirmed.

<Measurement of CO ₂ adsorption isotherm>
100 mg of the organic silica-based porous material (Comparative Example 1) was used for each test, and BELSORP-MAX-12-N-T-HL manufactured by Microtrack Bell was used as a measuring device, and 0 ° C, 40 ° C, 60 ° C, 80 ° C. The CO ₂ adsorption isotherm was measured at each temperature of ° C and 100 ° C. The obtained result is shown in FIG.

As is apparent from the results shown in FIG. 6, the organic silica porous material obtained in Comparative Example 1 had an increased amount of CO ₂ adsorbed at lower temperatures. The organosilica-based porous material obtained in Comparative Example 1 has a CO ₂ pressure (partial pressure) of 15 kPa in the temperature range of 60 ° C. or higher (an approximate fraction of CO ₂ in the exhaust gas from the power plant). (When pressure is assumed), the adsorption amount of CO ₂ is 3 cm ³ (STP) / g or less (when the temperature is 60 ° C. or more), and in the high temperature range of 60 ° C. or more, the adsorption amount of CO ₂ is It was not enough.

(Comparative Example 2)
Instead of using a silane raw material consisting of 9.2 g (0.0604 mol) of tetramethoxysilane and 4.7 g (0.0262 mol) of aminopropyltrimethoxysilane, 6.6 g (0.0434 mol) of tetramethoxysilane and An organic silica-based porous material was obtained in the same manner as in Example 1 except that a silane raw material consisting of 7.7 g (0.0429 mol) of aminopropyltrimethoxysilane was used.

With respect to the organic silica-based porous material thus obtained (Comparative Example 2), the specific surface area of the organic silica-based porous material, the average pore diameter (average pore diameter) of the sample, and the mass ratio of the organic components in the porous material And the Si-NMR chart was measured by adopting the same method as the measurement method employed in Example 1. As a result of such measurement, the organosilica-based porous body (Comparative Example 2) has a specific surface area of 42.5 m ² / g, and the sample obtained by calculation (the porous body at 550 ° C. for 6 hours). The average pore diameter (average pore diameter) of the heat-treated sample (fired product) was 2.06 nm. The organic silica based porous material (Comparative Example 2) has an organic component mass ratio of 0.202 (20.2 mass%), and the organic component ratio per average pore diameter (the mass of the organic component per pore diameter). Ratio: [mass ratio of organic components] / [average pore diameter of sample]) was confirmed to be 0.098 / nm. Furthermore, from the graph of the measured Si-NMR spectrum, the organosilica porous body (Comparative Example 2) has a structure in which an aminopropyl group (basic functional group) is bonded to silicon (Si). Was confirmed.

<Measurement of CO ₂ adsorption isotherm>
100 mg of the organosilica-based porous material (Comparative Example 2) was used for each test, and BELSORP-MAX-12-N-T-HL manufactured by Microtrack Bell was used as a measuring device, and 0 ° C., 40 ° C., 60 ° C., 80 The CO ₂ adsorption isotherm was measured at each temperature of ° C and 100 ° C. The obtained results are shown in FIG.

As is clear from the results shown in FIG. 7, the organic silica porous material obtained in Comparative Example 2 had an increased amount of CO ₂ adsorbed as the temperature decreased. Note that the organic silica porous material obtained in Comparative Example 2 has a CO ₂ pressure (partial pressure) of 15 kPa in the temperature range of 60 ° C. or higher (an approximate fraction of CO ₂ in the exhaust gas from the power plant). (When pressure is assumed), the adsorption amount of CO ₂ is 0.45 cm ³ (STP) / g or less (when the temperature is 60 ° C. or more), and in the high temperature range of 60 ° C. or more, the adsorption of CO ₂ The amount was not enough.

(Comparative Example 3)
The step of obtaining a mixed solution is a mixed solution of 1.54 g (0.00653 mol) of decyltrimethylammonium chloride (surfactant), 2.28 mL of 1N sodium hydroxide solution, 297.7 g of water and 100 g of methanol. By changing to the step of adding to the step to obtain a mixed solution, the type of the mixed solution to be used is changed,
Except for changing the type of silane raw material to be used by changing the silane raw material to one consisting of 11.9 g (0.0782 mol) of tetramethoxysilane and 1.6 g (0.0089 mol) of aminopropyltrimethoxysilane. In the same manner as in Example 1, an organic silica porous material was obtained.

Regarding the organic silica-based porous material thus obtained (Comparative Example 3), the specific surface area of the organic silica-based porous material, the average pore diameter (average pore diameter) of the sample, and the mass ratio of the organic components in the porous material And the Si-NMR chart was measured by adopting the same method as the measurement method employed in Example 1. As a result of such measurement, the organic silica-based porous material (Comparative Example 3) has a specific surface area of 17.1 m ² / g, and the sample obtained by calculation (the porous material is heated at 550 ° C. for 6 hours). The average pore diameter (average pore diameter) of the heat-treated sample (baked product) was 2.46 nm. The organic silica based porous material (Comparative Example 3) has an organic component mass ratio of 0.124 (12.4 mass%), and an organic component ratio per average pore diameter (organic component per average pore diameter). Mass ratio: [mass ratio of organic components] / [average pore diameter of sample]) was confirmed to be 0.05 / nm. Furthermore, from the graph of the measured Si-NMR spectrum, the organosilica porous body (Comparative Example 3) has a structure in which an aminopropyl group (basic functional group) is bonded to silicon (Si). Was confirmed.

<Measurement of CO ₂ adsorption isotherm>
100 mg of the organosilica-based porous material (Comparative Example 3) was used for each test, and BELSORP-MAX-12-N-T-HL manufactured by Microtrack Bell was used as a measuring device, and 0 ° C., 60 ° C., 80 ° C., 100 The CO ₂ adsorption isotherm was measured at each temperature of ° C. The obtained result is shown in FIG.

As is clear from the results shown in FIG. 8, the organic silica-based porous material obtained in Comparative Example 3 had an increased amount of CO ₂ adsorbed at lower temperatures. Incidentally, the resulting organic silica porous material in Comparative Example 3, in a temperature range of not lower than 60 ° C., the amount of adsorption of CO ₂ when the pressure of CO ₂ (partial pressure) is 15kPa is 3.48cm ³ (STP ) / G or less, and the CO ₂ adsorption amount was not sufficient in the temperature range of 60 ° C. or higher.

[Evaluation of properties of porous materials]
<About the structure of the porous body obtained in Examples 1-5 and Comparative Examples 1-3>
The organic silica based porous materials obtained in Examples 1 to 5 have a structure in which a basic functional group (aminopropyl group, aminoethylaminopropyl group or aminoethylaminoethylaminopropyl group) is bonded to silicon (Si). The specific surface area is 30 m ² / g or less, and the value obtained by dividing the mass ratio (organic component ratio) of the organic components in the porous body by the average pore diameter ([mass ratio of organic components] / [ It was confirmed that the average pore diameter of the sample]) was 0.06 / nm or more.

On the other hand, although the porous bodies obtained in Comparative Examples 1 and 3 have a structure in which a basic functional group (aminopropyl group) is bonded to silicon (Si), the mass ratio of organic components in the porous body (organic component ratio) ) Divided by the average pore diameter ([mass ratio of organic components] / [average pore diameter of sample]) was less than 0.06 / nm. Moreover, although the porous body obtained in Comparative Example 2 has a structure in which a basic functional group (aminopropyl group) is bonded to silicon (Si), the value of the specific surface area exceeds 30 m ² / g. It was confirmed that

<Adsorption properties of CO ₂ obtained porous body in Examples 1-5 and Comparative Examples 1-3>
The exhaust gas from the power plant, the exhaust gas from the automobile, and further the exhaust gas from the factory, etc., in which the partial pressure of CO ₂ is generally in the range of about 10 to 20 kPa. the obtained porous body by 5, where the pressure of CO ₂ was confirmed adsorption amount of CO ₂ in each porous body in the region of 10 to 20 kPa, both the adsorption of CO ₂ at a temperature of 60 ° C. 7 .3 cm ³ (STP) / g or more (the value of the porous body obtained in Example 3 under the condition of 10 kPa is the lowest value), and the CO ₂ adsorption amount is 8. It was confirmed that the value was 3 cm ³ (STP) / g or more (the value obtained under the condition of 10 kPa of the porous body obtained in Example 3 was the lowest value). On the other hand, with respect to the porous bodies obtained in Comparative Examples 1 to 3, based on FIGS. 6 to 8, the amount of CO ₂ adsorption of each porous body in the region where the CO ₂ pressure is 10 to 20 kPa was confirmed. The adsorption amount of CO _{2 at} a temperature condition of 60 ° C. is a value of 3.3 cm ³ (STP) / g or less (the value of the porous body obtained in Comparative Example 1 under the 20 kPa condition is the highest value). In the temperature condition of 80 ° C., the amount of CO ₂ adsorbed becomes a value of 2.2 cm ³ (STP) / g or less (the value obtained under the condition of 20 kPa of the porous body obtained in Comparative Example 1 is the highest value). It was confirmed that

Thus, from the graphs shown in FIGS. 1 to 8, any of the CO ₂ adsorbents of the present invention comprising the organic silica-based porous material obtained in Examples 1 to 5 has a CO ₂ pressure of 10 to 20 kPa. In the region, when compared under the same temperature conditions, a relatively high temperature range of 60 ° C. or higher (more preferably 60 to 100 ° C., and more preferably) than the adsorbent made of the porous body obtained in Comparative Examples 1 to 3. It is clear that CO ₂ can be adsorbed at a higher level at 60-80 ° C.). From such a result, CO ₂ adsorbent of the present invention (Examples 1 to 5) is, 60 ° C. or more hot temperature range (preferably 60 to 100 [° C., more preferably 60-80 ° C.) of CO ₂ in It turns out that it can fully adsorb | suck.

As described above, according to the present invention, it is possible to provide a CO ₂ adsorbent capable of sufficiently adsorbing CO ₂ in a relatively high temperature range. Therefore, the CO ₂ adsorbent of the present invention is particularly useful as a material for adsorbing and removing carbon dioxide (CO ₂ ) from a relatively high temperature exhaust gas such as exhaust gas from a power plant or automobile exhaust gas.

Claims (3)

A CO ₂ adsorbent comprising an organic silica-based porous body,
The organosilica-based porous body is
The following general formula (1) in which a basic functional group is bonded to silicon in the skeleton of the porous body:
X-Si (1)
[In the formula (1), X represents the formula: R ¹ —NH— (CH ₂ ) _n — (wherein R ¹ is any one selected from the group consisting of a hydrogen atom, an aminoalkyl group, and an aminoalkylaminoalkyl group. And n represents an integer of 1 to 6.) represents a basic functional group. ]
Having a structure represented by
The specific surface area determined based on the nitrogen adsorption isotherm of the porous body is 1 to 30 m ² / g,
The mass ratio of the organic component in the porous body is obtained by dividing by the average pore diameter of the sample obtained based on the nitrogen adsorption isotherm of the sample obtained by heating the porous body at 550 ° C. for 6 hours. The obtained value ([mass ratio of organic components] / [average pore diameter of sample]) is 0.06 / nm or more,
CO ₂ adsorbent characterized by this. R ¹ is any one selected from the group consisting of a hydrogen atom, an aminoalkyl group having 1 to 5 carbon atoms, and an aminoalkylaminoalkyl group having 1 to 5 carbon atoms in each aminoalkyl moiety. The CO ₂ adsorbent according to claim 1, wherein: X in the general formula (1) is any basic functional group selected from the group consisting of an aminopropyl group, an aminoethylaminopropyl group, and an aminoethylaminoethylaminopropyl group. The CO ₂ adsorbent according to claim 1 or 2.