Amino compound-supported porous substrate, acidic gas adsorbent, and carbon dioxide adsorbent

Abstract

This amino compound-supported porous substrate has: a porous substrate having a co-continuous structure formed by coarse pores and a framework containing micropores; and an amino compound supported in at least some of the pores of the porous substrate. The mode pore diameter of the coarse pores in the porous substrate is 0.5-10.0 μm. The pore volume of the coarse pores in the porous substrate is 0.40-0.95 mL / mL per unit volume of the porous substrate. The mode pore diameter of the micropores in the porous substrate is 50.0 nm or more and less than 500.0 nm. The pore volume of the micropores in the porous substrate is 0.05-0.50 mL / mL per unit volume of the porous substrate.

Description

Amino compound-supported porous substrate, and acid gas adsorbent and carbon dioxide adsorbent

[0001] The present invention relates to a porous substrate supporting amino compounds, as well as an acidic gas adsorbent and a carbon dioxide adsorbent.

[0002] In recent years, due to increased awareness of environmental issues, carbon dioxide, NO and NO contained in exhaust gases have become a concern. ２ Nitrogen oxides such as SO and SO ２ Emissions of sulfur oxides such as those found in industrial gases are a cause for concern. For example, carbon dioxide separation and recovery technologies, which are a contributing factor to global warming, are attracting attention, and research is underway on technologies to separate and recover carbon dioxide emitted from thermal power plants and steel mills. One known carbon dioxide separation and recovery technology is a method that uses a carbon dioxide adsorbent in which amino compounds are supported on a porous material.

[0003] For example, the applicant previously proposed an amino compound-supported porous substrate for carbon dioxide adsorption, in which polyethyleneimine is supported inside the pores by impregnating a porous substrate having mesopores and macropores with a polyethyleneimine solution (see Patent Document 1).

[0004] US2025 / 0018371A1

[0005] However, when an adsorbent using a porous substrate is used, for example, to adsorb carbon dioxide from the air, a problem arises: it adsorbs not only carbon dioxide but also water. Desorbing carbon dioxide from an adsorbent that has also adsorbed water requires more energy than when only carbon dioxide is being desorbed. Therefore, the present invention aims to provide an amino compound-supported porous substrate in which water adsorption is suppressed compared to conventional materials.

[0006] The present invention relates to an amino compound-supported porous substrate having a porous substrate having a co-continuous structure formed by a framework containing micropores and coarse pores, and an amino compound supported in at least some of the pores of the porous substrate, wherein the porous substrate has a most frequent pore diameter of the coarse pores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion method of 0.5 μm to 10.0 μm, the porous substrate has a pore volume of the coarse pores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion method of 0.40 mL / mL to 0.95 mL / mL per unit volume of the porous substrate, and the porous substrate has a most frequent pore diameter of the micropores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion method of 50.0 nm to less than 500.0 nm. The present invention provides an amino compound-supported porous substrate in which the pore volume of the micropores, measured by mercury intrusion in the range of pore diameter 2.0 nm to 500.0 μm, is 0.05 mL / mL to 0.50 mL / mL per unit volume of the porous substrate.

[0007] Furthermore, the present invention provides an acidic gas adsorbent containing the aforementioned amino compound-supported porous substrate.

[0008] The present invention also provides a carbon dioxide adsorbent containing the aforementioned porous substrate supporting an amino compound.

[0009] Figure 1 is a schematic diagram showing an enlarged view of the main part of the porous substrate used in the present invention. Figures 2(a) and 2(b) are SEM images of the porous substrate obtained in Production Example 1.

[0010] The present invention will be described below based on its preferred embodiments. The present invention relates to a porous substrate on which an amino compound is supported (hereinafter also referred to as "amino compound supported porous substrate").

[0011] First, the details of the amino compound will be described. In the amino compound-carrying porous base material of the present invention, since the amino compound is carried in at least part of the pores of the porous base material, the amino compound-carrying porous base material can be suitably used, for example, for gas adsorption. As the amino compound, a primary amino group (-NH ２ ), a secondary amino group (-NHR １ ), a tertiary amino group (-NR １ R ２ ), and / or a quaternary ammonium group (-N ＋ R １ R ２ R ３ ) include various compounds. R １ , R ２ and R ３ are each independently, for example, an optionally substituted alkyl group, an optionally substituted aryl group, and the like. Details of the substituents will be described later.

[0012] The amino compound of the present embodiment is preferably a polyamine compound. As used herein, the term "polyamine compound" refers to a compound containing two or more amino groups in the molecule. It is preferable from the viewpoint of increasing the adsorption amount of gas when the amino compound-carrying porous base material of the present invention is used, for example, for gas adsorption, that the compound carried on the porous base material is a polyamine compound.

[0013] Polyamine compounds may be low-molecular-weight amino compounds or high-molecular-weight amino compounds. In this specification, "high-molecular-weight amino compounds" refers to compounds with a mass-average molecular weight of 200 or more. Compounds with a mass-average molecular weight of less than 200 are referred to as "low-molecular-weight amino compounds" in this specification. Examples of low-molecular-weight amino compounds include aliphatic amines and aromatic amines. Examples of aliphatic amines include chain-type aliphatic amines and cyclic aliphatic amines, such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N,N'-bis(2-hydroxyethyl)ethylenediamine, piperazine, and 2-aminoethylpiperazine. Examples of aromatic amines include 2-picolylamine and m-xylenediamine. Examples of high-molecular-weight amino compounds include linear polyethyleneimine, branched polyethyleneimine, and polypropyleneimine. The above-mentioned amino compounds can be used individually or in combination of two or more.

[0014] From the viewpoint of effectively increasing the amount of gas adsorption, the amino compound in this embodiment is more preferably a polyamine compound and a high molecular weight amino compound. Since high molecular weight amino compounds have a higher adsorption capacity to gases, especially carbon dioxide, compared to low molecular weight amino compounds, the amino compound is more preferably a polyamine compound and a high molecular weight amino compound. Examples of polyamine compounds that are such high molecular weight amino compounds include linear polyethyleneimine, branched polyethyleneimine, and polypropyleneimine. From the viewpoint of effectively improving the adsorption capacity to gases, especially carbon dioxide, branched polyethyleneimine is preferred.

[0015] The mass-average molecular weight of high-molecular-weight amino compounds is measured by GPC (gel permeation chromatography). In this specification, "mass-average molecular weight" refers to the mass-average molecular weight measured by GPC analysis using polystyrene as the reference.

[0016] The polymeric amino compound is preferably further possessing a substituent (hereinafter also referred to as "substituent A"). In other words, the polymeric amino compound is preferably a polyamine compound having substituent A. In particular, it is preferable that the hydrogen atom bonded to the nitrogen atom in the amino group is substituted with substituent A for the following reasons: When the polymeric amino compound is a polyamine compound having substituents, there are fewer amino groups that can form hydrogen bonds with water molecules compared to when there are no substituents. Therefore, since the number of amino groups that can adsorb water molecules is reduced, the porous substrate supporting the amino compound of the present invention can suppress water adsorption more effectively than conventional substrates. For this reason, it is preferable that substituent A of the polymeric amino compound exhibits hydrophobicity. Here, "exhibiting hydrophobicity" refers to a substituent that can reduce the polarity of the amino compound having substituents compared to the amino compound before substitution. Substituent A that can bond to an amino compound and exhibits hydrophobicity is particularly preferable to have a saturated aliphatic hydrocarbon moiety in its structural framework.

[0017] In this embodiment, substituent A only needs to have a saturated aliphatic hydrocarbon moiety in its structural framework, and may also have an unsaturated aliphatic hydrocarbon moiety as long as it exhibits hydrophobicity. The saturated aliphatic hydrocarbon moiety may be linear, branched, or cyclic. Examples of substituent A having a saturated aliphatic hydrocarbon moiety include alkyl groups having 1 to 20 carbon atoms, hydroxyalkyl groups having 2 to 20 carbon atoms, and cycloalkyl groups having 3 to 8 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, and dodecyl groups. A hydroxyalkyl group is a functional group in which one or more hydrogen atoms of the above-mentioned alkyl group are substituted with a hydroxyl group. Specific examples include, for example, 2-hydroxyethyl group, 1-hydroxypropyl-2-yl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group, 4-hydroxybutan-2-yl group, 5-hydroxypentyl group, 6-hydroxyhexyl group, 5-hydroxy-2-methylpentyl group, and 2-hydroxydodecyl group. Examples of cycloalkyl groups include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, and cyclooctyl group. The alkyl group, hydroxyalkyl group, and cycloalkyl group may each further have a substituent (hereinafter also referred to as "substituent B"). Examples of substituent B include alkenyl group, alkynyl group, alkoxy group, phenyl group, and halogen group. When the alkyl group, the hydroxyalkyl group, and the cycloalkyl group each have substituent B, the above-mentioned carbon number represents the carbon number of the saturated aliphatic hydrocarbon moiety after the hydrogen atom substitution.

[0018] When a polyamine compound has substituent A, the degree of substitution is preferably within a predetermined range. The degree of substitution can be evaluated by a value R obtained by dividing the number of substituent A in the polyamine compound by the number of nitrogen atoms in the polyamine compound. Specifically, from the viewpoint of more effectively suppressing water adsorption than conventional methods, the value R is preferably 0.05 or higher, more preferably 0.10 or higher, and even more preferably 0.20 or higher. From the viewpoint of making the above-mentioned advantages even more pronounced, a larger value R is preferable, but it may be 1.00 or lower, 0.75 or lower, or 0.50 or lower. The method for measuring the value R will be explained in the examples described later.

[0019] From the viewpoint of obtaining an amino compound-supported porous substrate with suppressed water adsorption compared to conventional materials, it is preferable that the hydrogen atom bonded to the nitrogen atom in the amino group located at the terminus of the polyamine compound in this embodiment is substituted with substituent A. For example, when a primary amino group contained in the polyamine compound is substituted, it is preferable that an R-NH- group (where R is a substituent) is located at the terminus of the polyamine compound. From the viewpoint of effectively obtaining an amino compound-supported porous substrate with suppressed water adsorption compared to conventional materials, it is preferable that substituent A in the polyamine compound of this embodiment is an alkyl group having 1 to 12 carbon atoms, which may be substituted with substituent B. Furthermore, from the viewpoint of reducing the polarity of the amino compound having substituent A compared to the amino compound before substitution, it is even more preferable that substituent A is an isopropyl group.

[0020] Next, the details of the porous substrate will be described. The porous substrate constitutes the majority of the amino compound-supported porous substrate of the present invention and has a large number of pores. In the present invention, the amino compound is supported in at least some of the pores of the porous substrate as described above. The porous substrate of this embodiment preferably has at least bimodal pores. This makes it possible to increase the amount of gas adsorbed compared to an adsorbent on a porous substrate having unimodal pores with the same amount of amino compound supported. The mechanism by which this effect is achieved will be described in detail later. Hereinafter, the bimodal pores of the porous substrate will be referred to as micropores and coarse pores, respectively. In this specification, "micropores" refer to pores with a diameter of 2.0 nm or more and less than 500.0 nm. "Coarse pores" refer to pores with a diameter of 0.5 μm or more.

[0021] Porous substrates, due to their structure, are used to adsorb gases such as carbon dioxide. However, conventionally, due to capillary condensation in the pores of porous substrates, they also adsorb water from the air. In this case, if a vacuum pump is used to desorb the gas from the porous substrate, the presence of water requires time to reduce the pressure to the desired level, necessitating prolonged operation of the vacuum pump. Therefore, a lot of energy was required to desorb the gas from the porous substrate. To improve this, the inventors conducted extensive research and found that increasing the size of the pores in the porous substrate and suppressing capillary condensation is effective. "Capillary condensation" refers to the phenomenon in which water vapor condenses within pores and aggregates as a liquid. Increasing the size of the pores suppresses capillary condensation. The inventors also conducted extensive research on this matter and found an effective pore size to suppress capillary condensation and thus suppress water adsorption. As a result, it became possible to reduce the amount of energy required to desorb gas from the porous substrate compared to conventional methods.

[0022] For the reasons stated above, it is preferable that the most frequent pore size of the porous substrate in this embodiment is within a predetermined range. Specifically, it is preferable that the most frequent pore size Dr of the porous substrate, measured by the mercury intrusion method in the range of pore size from 2.0 nm to 500.0 μm, is 50.0 nm or more, more preferably greater than 50.0 nm, even more preferably 70.0 nm or more, and even more preferably 80.0 nm or more. Having the most frequent pore size Dr within this range effectively suppresses capillary condensation, making it possible to obtain an amino compound-supported porous substrate with suppressed water adsorption compared to conventional materials. Furthermore, from the viewpoint of suppressing a decrease in the skeleton density of the porous substrate, it is preferable that the most frequent pore size Dr is less than 500.0 nm, even more preferably 300.0 nm or less, and even more preferably 200.0 nm or less.

[0023] The inventors have discovered that an additional effect is achieved when the most frequent pore size Dr of the micropores in a porous substrate is 50.0 nm or greater. Specifically, they found that when an amino compound-supported porous substrate is immersed in water, or when it is exposed to condensation water generated in a high-humidity environment, the elution of the amino compound supported in the pores into the water or condensation water is suppressed. Suppression of amino compound elution is preferable because it allows the amino compound-supported porous substrate to maintain its improved adsorption capacity to gases, particularly carbon dioxide, even in environments where it is exposed to water. A high-humidity environment is, for example, an environment in which water vapor is supplied to the amino compound-supported porous substrate.

[0024] In the porous substrate of this embodiment, it is also preferable that the most frequent pore diameter of the coarse pores is within a predetermined range. Specifically, the porous substrate preferably has a most frequent pore diameter Ds of coarse pores measured by the mercury intrusion method in the range of pore diameters from 2.0 nm to 500.0 μm, of 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.2 μm or more. Having the most frequent pore diameter Ds within this range ensures, for example, a passage for the gas when the amino compound-supported porous substrate of the present invention is used for gas adsorption, thereby increasing the amount of gas adsorbed. Furthermore, from the viewpoint of suppressing a decrease in the mechanical strength of the porous substrate, the most frequent pore diameter Ds is preferably 10.0 μm or less, more preferably 5.0 μm or less, and even more preferably 3.0 μm or less.

[0025] The methods for measuring the most frequent pore diameter Dr of micropores and the most frequent pore diameter Ds of coarse pores will be illustrated in the examples described later.

[0026] In the porous substrate of this embodiment, it is preferable that the value of Ds / Dr, which is the ratio of the most frequent pore size Ds (nm) of coarse pores to the most frequent pore size Dr (nm) of micropores, is within a predetermined range. Specifically, from the viewpoint of obtaining an amino compound-supported porous substrate that simultaneously exhibits suppression of capillary condensation, suppression of elution of amino compounds into water, and improvement of gas adsorption capacity, it is preferable that the value of Ds / Dr is 2 or more, more preferably 5 or more, and even more preferably 10 or more. From a similar viewpoint, it is preferable that the value of Ds / Dr is 100 or less, more preferably 80 or less, even more preferably 60 or less, and even more preferably 40 or less.

[0027] To set the most frequent pore size Dr of micropores within the above range, it is preferable, for example, to change the type of micropore-forming agent or the heating temperature or heating method in step (b) in the manufacturing method described later. To set the most frequent pore size Ds of coarse pores within the above range, it is preferable, for example, to adjust the rate of the phase separation process (typically spinodal decomposition) or change the type of coarse pore-forming agent in the manufacturing method described later.

[0028] In the porous substrate of the present embodiment, the pores thereof are larger than those of conventional porous substrates, and this feature can also be evaluated based on the magnitude of the pore volume. Therefore, it is also preferable that the pore volume of the porous substrate falls within a predetermined range. Specifically, in the porous substrate, the pore volume Vr of micropores measured by mercury porosimetry in a pore diameter range of 2.0 nm or more and 500.0 μm or less is preferably 0.05 mL / mL or more, more preferably 0.10 mL / mL or more, and still more preferably 0.20 mL / mL or more per unit volume of the porous substrate. When the pore volume Vr falls within this range, by increasing the loading amount of the amino compound in the micropores and effectively suppressing capillary condensation, an amino compound-supported porous substrate in which water adsorption is suppressed more than in conventional ones can be obtained. In addition, from the viewpoint of suppressing a decrease in the framework density of the porous substrate, the pore volume Vr is preferably 0.50 mL / mL or less, more preferably 0.45 mL / mL or less, still more preferably 0.40 mL / mL or less, and even more preferably 0.35 mL / mL or less per unit volume of the porous substrate. Note that the "unit volume of the porous substrate" as used herein refers to the apparent volume of the porous substrate.

[0029] In the porous substrate of the present embodiment, it is also preferable that the pore volume of macropores falls within a predetermined range. Specifically, in the porous substrate, the pore volume Vs of macropores measured by mercury porosimetry in a pore diameter range of 2.0 nm or more and 500.0 μm or less is preferably 0.40 mL / mL or more, more preferably 0.45 mL / mL or more, and still more preferably 0.50 mL / mL or more per unit volume of the porous substrate. When the pore volume Vs falls within this range, for example, when the amino compound-supported porous substrate of the present invention is used for gas adsorption, a passage for the gas can be secured, and the gas adsorption amount can be increased. In addition, from the viewpoint of suppressing a decrease in the mechanical strength of the porous substrate, the pore volume Vs is preferably 0.95 mL / mL or less, more preferably 0.80 mL / mL or less, and still more preferably 0.70 mL / mL or less per unit volume of the porous substrate. Note that the "unit volume of the porous substrate" as used herein refers to the apparent volume of the porous substrate.

[0030] In the porous substrate of the present embodiment, it is also preferable that the total pore volume falls within a predetermined range. Specifically, the total pore volume Va of the porous substrate, measured within a pore diameter range of 2.0 nm to 500.0 μm inclusive by mercury porosimetry, is preferably 0.55 mL / mL or more per unit volume of the porous substrate, more preferably 0.65 mL / mL or more, and still more preferably 0.75 mL / mL or more. When the total pore volume Va falls within this range, for example, when the amino compound-supporting porous substrate of the present invention is used for gas adsorption, passages for the gas can be secured, and the gas adsorption amount can be increased. The upper limit of the total pore volume Va is preferably 1.00 mL / mL. From the viewpoint of suppressing a decrease in the skeleton density and a decrease in mechanical strength of the porous substrate, the total pore volume Va is preferably 0.95 mL / mL or less per unit volume of the porous substrate, and more preferably 0.90 mL / mL or less. The "unit volume of the porous substrate" as used herein refers to the apparent volume of the porous substrate.

[0031] Methods for measuring the pore volume Vr of micropores, the pore volume Vs of macropores, and the total pore volume Va will be exemplified in the Examples described later.

[0032] In order to adjust the pore volume Vr of micropores to the above-mentioned range, it is suitable, for example, to change the type of micropore forming agent in the production method described later, or to change the heating temperature or heating method in step (b). In order to adjust the pore volume Vs of macropores to the above-mentioned range, it is suitable, for example, to adjust the rate of the phase separation process (typically spinodal decomposition) or to change the type of macropore forming agent in the production method described later.

[0033] It is preferable that the BET specific surface area of the porous substrate of the present embodiment falls within a predetermined range. Specifically, from the viewpoint of facilitating loading of an amino compound into the pores of the porous substrate, the BET specific surface area of the porous substrate is 20 m ２ / g or more, preferably 30 m ２ / g or more, more preferably 40 m ２It is even more preferable that the amount is 1 / g or more. Furthermore, from the viewpoint of effectively suppressing capillary condensation and effectively obtaining an amino compound-supported porous substrate with suppressed water adsorption compared to conventional materials, the BET specific surface area of ​​the porous substrate should be 200 m². ２ It is preferable that it be less than or equal to 150m ２ It is even more preferable that it be less than or equal to 100m ２ It is even more preferable that the amount be less than or equal to / g. The method for measuring the BET specific surface area will be illustrated in the examples described later.

[0034] In this embodiment, the porous substrate is preferably within a predetermined range of bulk density. Specifically, from the viewpoint of effectively obtaining a porous substrate having desired micropores and coarse pores, the bulk density of the porous substrate is preferably 0.10 g / mL or more, more preferably 0.13 g / mL or more, and even more preferably 0.15 g / mL or more. From a similar viewpoint, the bulk density of the porous substrate is preferably 0.50 g / mL or less, more preferably 0.40 g / mL or less, and even more preferably 0.30 g / mL or less. A method for measuring bulk density will be illustrated in the examples described later.

[0035] To achieve the above-mentioned BET specific surface area and bulk density of the porous substrate, it is preferable, for example, to change the type of micropore-forming agent or the heating temperature or heating method in step (b) in the manufacturing method described later. Alternatively, it is also preferable to adjust the rate of the phase separation process (typically spinodal decomposition) or change the type of coarse pore-forming agent in the manufacturing method described later.

[0036] In this embodiment, the porous substrate preferably has a co-continuous structure formed by a framework containing micropores and coarse pores. This increases the specific surface area of ​​the porous substrate, thereby increasing the amount of amino compounds that can be supported and reducing pressure loss. Specifically, as shown in Figure 1, the porous substrate 1 preferably has a co-continuous structure formed by a framework 3 containing micropores 4 and coarse pores 2. In other words, in the porous substrate 1, it is preferable that a large number of coarse pores 2 are formed by the framework 3, and that a large number of micropores 4 are formed within the framework 3. In the porous substrate 1 shown in the figure, the multiple micropores 4 open on the surface of the framework 3 and extend into the interior of the framework 3. The other end of the micropores 4 may be closed or open on the surface of the framework 3. The micropores 4 may also branch inside the framework 3 or intersect with other micropores 4. The framework 3 is a part made of the material that constitutes the porous substrate 1. In the porous substrate 1, the framework 3 intertwines with each other to form a large number of coarse pores 2. The coarse pores 2 may be branched within the porous substrate 1, or they may intersect with other coarse pores 2. The framework 3 and the coarse pores 2 each have a continuous three-dimensional network structure and are intertwined with each other, thereby forming a co-continuous structure between the framework 3 and the coarse pores 2. The presence of a co-continuous structure between the framework 3 and the coarse pores 2 in the porous substrate 1 can be confirmed by observing the surface or cross-section of the porous substrate 1 with a scanning electron microscope (hereinafter also referred to as "SEM").

[0037] The porous substrate in this embodiment is not particularly limited in shape. The porous substrate may be, for example, spherical, polyhedral, columnar, or flattened, or any combination thereof. Furthermore, the form of the porous substrate is not particularly limited. Examples of forms of the porous substrate include particles, lumps, and molded bodies. In this embodiment, the shape and form of the porous substrate and the shape and form of the amino compound-supported porous substrate are substantially the same. The porous substrate in this embodiment may also be a molded body. If the porous substrate is a molded body, there are no particular limitations on the shape of the molded body. For example, it may be spherical, polyhedral, columnar, or flattened, or any combination thereof.

[0038] Next, the amino compound-supported porous substrate of the present invention will be described. In the amino compound-supported porous substrate of the present invention, it is preferable that the amino compound is supported in at least some of the pores of the porous substrate. In this specification, "supported" includes a mode in which the porous substrate and the amino compound are chemically bonded (hereinafter also referred to as "chemical bonding modification"), and a mode in which the porous substrate and the amino compound are physically adsorbed (hereinafter also referred to as "non-chemical bonding modification"). In the amino compound-supported porous substrate of the present invention, either one mode or both modes may be used. Regardless of whether it is a chemical bonding modification or a non-chemical bonding modification, the amino compound-supported porous substrate of the present invention can suppress water adsorption more effectively than conventional materials.

[0039] In this embodiment, the amount of amino groups contained in the amino compound-supported porous substrate of the present invention is preferably 1.0 mmol / mL or more, more preferably 1.5 mmol / mL or more, and even more preferably 2.0 mmol / mL or more per unit volume of the amino compound-supported porous substrate. Having the amount of amino groups within this range allows for an increase in the amount of gas adsorbed when the amino compound-supported porous substrate of the present invention is used, for example, for gas adsorption. Furthermore, from the viewpoint of securing gas passages and increasing the amount of gas adsorbed, the amount of amino groups contained in the amino compound-supported porous substrate of the present invention is preferably 20.0 mmol / mL or less, more preferably 10.0 mmol / mL or less, even more preferably 5.0 mmol / mL or less, even more preferably 4.0 mmol / mL or less, and particularly preferably 3.0 mmol / mL or less per unit volume of the amino compound-supported porous substrate. The method for measuring the amount of amino groups will be illustrated in the examples described later.

[0040] The presence of an amino compound in the amino compound-supported porous substrate of the present invention can be evaluated by comparing the size of the pore volume before and after the amino compound is supported. Specifically, if the size of the pore volume after support is smaller than before support, it can be evaluated that the amino compound is supported in at least a portion of the pores. In particular, if the amino compound is supported in micropores, it becomes easier to utilize coarse pores as gas passages, thereby increasing the amount of gas adsorbed. For this reason, it is preferable that the pore volume of the micropores in the amino compound-supported porous substrate of the present invention is within a predetermined range. In the amino compound-supported porous substrate, the pore volume Vm of the micropores measured by the mercury intrusion method in the range of pore diameter 2.0 nm to 500.0 μm is preferably 0.30 mL / mL or less, more preferably 0.25 mL / mL or less, and even more preferably 0.20 mL / mL or less per unit volume of the amino compound-supported porous substrate. When the pore volume Vm is within this range, the amount of amino compound loaded onto the micropores increases, thereby increasing the amount of gas adsorbed. The lower limit of the pore volume Vm is not particularly limited. For example, it may be 0.01 mL / mL or higher. Note that the "unit volume of the amino compound-loaded porous substrate" as used herein refers to the apparent volume of the amino compound-loaded porous substrate.

[0041] In the amino compound-supported porous substrate of the present invention, it is also preferable that the pore volume of the coarse pores is within a predetermined range. Specifically, the pore volume Vn of the coarse pores of the amino compound-supported porous substrate, measured by mercury intrusion in the range of pore diameter 2.0 nm to 500.0 μm, is preferably 0.40 mL / mL or more, more preferably 0.50 mL / mL or more, and even more preferably 0.55 mL / mL or more per unit volume of the amino compound-supported porous substrate. Having the pore volume Vn within this range allows for the support of a sufficient amount of amino compound, and when the amino compound-supported porous substrate of the present invention is used for gas adsorption, it ensures a passage for the gas and increases the amount of gas adsorbed. The upper limit of the pore volume Vn is not particularly limited. For example, it may be 0.95 mL / mL or less, 0.90 mL / mL or less, or 0.85 mL / mL or less per unit volume of the amino compound-supported porous substrate. Note that the "unit volume of the amino compound-supported porous substrate" as used here refers to the apparent volume of the amino compound-supported porous substrate.

[0042] In the amino compound-supported porous substrate of the present invention, it is also preferable that the total pore volume is within a predetermined range. Specifically, the total pore volume Vb of the amino compound-supported porous substrate, measured by mercury intrusion in the range of pore diameters from 2.0 nm to 500.0 μm, is preferably 0.50 mL / mL or more, more preferably 0.60 mL / mL or more, and even more preferably 0.70 mL / mL or more per unit volume of the amino compound-supported porous substrate. Having the total pore volume Vb within this range ensures that a passage for the gas can be secured when the amino compound-supported porous substrate of the present invention is used for gas adsorption, and the amount of gas adsorbed can be increased. The upper limit of the total pore volume Vb is not particularly limited. For example, it may be 0.95 mL / mL or less, 0.90 mL / mL or less, or 0.85 mL / mL or less per unit volume of the amino compound-supported porous substrate. Here, "unit volume of the amino compound-supported porous substrate" refers to the apparent volume of the amino compound-supported porous substrate.

[0043] Methods for measuring the pore volume Vm of micropores, the pore volume Vn of coarse pores, and the total pore volume Vb will be illustrated in the examples described later.

[0044] In order to set the pore volume Vm of the micropores and the pore volume Vn of the coarse pores within the above-mentioned ranges, it is preferable, for example, to adjust the amount of amino compound supported in the pores in the manufacturing method described later.

[0045] The porous substrate supporting the amino compound of the present invention preferably has a BET specific surface area within a predetermined range. Specifically, when the porous substrate supporting the amino compound of the present invention is used for gas adsorption, it is preferable that it supports a sufficient amount of the amino compound, secures a passage for the gas, and increases the amount of gas adsorbed, the BET specific surface area of ​​the porous substrate supporting the amino compound is 2.0 m². ２ It is preferable that the amount is 3.0 m or more. ２ It is even more preferable that it be 3.5 m or more per gram. ２ It is even more preferable that the amount is greater than or equal to 1 / g. From a similar viewpoint, the BET specific surface area of ​​the amino compound-supported porous substrate is 40.0 m². ２ It is preferable that the amount be less than or equal to 30.0 m ２ It is even more preferable that it be less than or equal to 25.0 m ２ It is even more preferable that the amount be less than or equal to / g. The method for measuring the BET specific surface area will be illustrated in the examples described later.

[0046] The amino compound-supported porous substrate of the present invention preferably has a bulk density within a predetermined range. Specifically, when the amino compound-supported porous substrate of the present invention is used for gas adsorption, from the viewpoint of securing a passage for the gas and increasing the amount of gas adsorbed, the bulk density of the amino compound-supported porous substrate is preferably 0.10 g / mL or more, more preferably 0.15 g / mL or more, and even more preferably 0.20 g / mL or more. From a similar viewpoint, the bulk density of the amino compound-supported porous substrate is preferably 0.70 g / mL or less, more preferably 0.50 g / mL or less, and even more preferably 0.40 g / mL or less. A method for measuring bulk density will be illustrated in the examples described later.

[0047] Next, a preferred method for producing the amino compound-supported porous substrate of the present invention will be described. The amino compound-supported porous substrate of the present invention can be obtained by supporting an amino compound on a porous substrate formed by heating a gel in a gas to create pores.

[0048] This manufacturing method comprises the following steps in this order. Additional steps may be performed between each step as needed. • Step (a): A step to manufacture a gel. • Step (b): A step to form pores in the gel skeleton manufactured in step (a). • Step (c): A step to manufacture a porous substrate by washing and / or drying the gel used in step (b) as needed, and then firing it. • Step (d): A step to support an amino compound on the porous substrate manufactured in step (c). Each of these steps will be explained below.

[0049] [Step (a)] Step (a) is a step in which a gel (hereinafter also referred to as the "first gel") is manufactured by a predetermined method. The first gel has a co-continuous structure formed by a skeletal phase and a solvent phase. In this manufacturing method, from the viewpoint of successfully obtaining the target porous substrate, it is preferable that the first gel is a polymetalloxane gel. A polymetalloxane is an inorganic polymer whose main chain skeleton is a metalloxane bond. A metalloxane bond is a bond between a metalloid or metallic element and an oxygen atom, i.e., an M-O bond (where M represents a metalloid or metallic element).

[0050] Examples of metalloid elements represented by M include silicon. Examples of metallic elements represented by M include aluminum, tin, cerium, titanium, zirconium, vanadium, chromium, iron, cobalt, nickel, palladium, platinum, copper, silver, gold, and zinc. However, from the viewpoint of ease of manufacturing porous substrates, it is preferable to use one or more selected from aluminum, tin, cerium, titanium, and zirconium.

[0051] Polymetalloxane gels can be manufactured by the sol-gel method. The sol-gel method can be carried out according to conventional procedures. An example of the sol-gel method is as follows:

[0052] The sol-gel process includes a sol-making step and a gel-making step. Details of the sol-gel process can be found in the applicant's earlier application WO2022 / 163831, which is incorporated herein by reference as part of this specification. The macropore-forming agent described in WO2022 / 163831 is to be interpreted as the coarse pore-forming agent in this invention. In the sol-making step, a reaction solution containing a ceramic precursor, a catalyst, and a coarse pore-forming agent is stirred to produce a sol.

[0053] The ceramic precursor is not particularly limited in type as long as it can form a polymetalloxane gel. Examples of ceramic precursors include metalloid compounds having hydroxyl groups and / or hydrolyzable functional groups (e.g., silicon compounds), or metal compounds having hydroxyl groups and / or hydrolyzable functional groups (e.g., aluminum compounds, tin compounds, cerium compounds, titanium compounds, and zirconium compounds, etc.). A hydrolyzable functional group is a functional group that is converted to a hydroxyl group by hydrolysis. The total number of hydroxyl groups and hydrolyzable functional groups in each of the metalloid and metal compounds may be one or two, but from the viewpoint of producing a polymetalloxane gel having a highly crosslinked structure by metalloxane bonds (M-O bonds), it is preferable to have three or more, and more preferably four. When each of the metalloid and metal compounds has two or more hydrolyzable functional groups, the types of the two or more hydrolyzable functional groups may be the same or different.

[0054] The silicon compound having a hydroxyl group and / or a hydrolyzable functional group is preferably an alkoxysilane. Examples of alkoxysilanes include tetraalkoxysilane, trialkoxysilane, dialkoxysilane, and monoalkoxysilane. Of these, tetraalkoxysilane is preferred from the viewpoint of facilitating hydrolysis and polycondensation reactions. Examples of tetraalkoxysilanes include tetramethoxysilane and tetraethoxysilane.

[0055] The ceramic precursor may be a metal salt (e.g., aluminum salt, tin salt, and cerium salt) that is converted to a hydroxide by hydrolysis. Examples of aluminum salts include aluminum nitrate, aluminum sulfate, and aluminum chloride. Examples of tin salts include tin nitrate, tin sulfate, and tin chloride. Examples of cerium salts include cerium nitrate, cerium sulfate, and cerium chloride. Of these, it is preferable to use one or more selected from aluminum chloride, tin chloride, and cerium chloride, from the viewpoint of facilitating the hydrolysis and polycondensation reactions.

[0056] The ceramic precursor may be sodium silicate or water glass. Water glass is a concentrated aqueous solution of sodium silicate. The type of water glass and the concentration of sodium silicate are not particularly limited, but from the viewpoint of availability and handling, the sodium silicate concentration of the water glass is preferably 20% by mass or more and 40% by mass or less. In this manufacturing method, water glass is preferred from the viewpoint of facilitating the polycondensation reaction.

[0057] Catalysts function as catalysts for hydrolysis reactions and / or polycondensation reactions. Examples of catalysts include acids and bases. Examples of acids include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid; and organic acids such as formic acid, acetic acid, oxalic acid, and citric acid. Examples of bases include hydroxides such as sodium hydroxide and potassium hydroxide; aqueous ammonia; carbonates such as sodium carbonate and sodium bicarbonate; amines such as trimethylammonium; ammonium hydroxides such as tert-butylammonium hydroxide; and alkali metal alkoxides such as sodium methoxide.

[0058] Coarse pore-forming agents contribute to the formation of coarse pores in porous substrates. Examples of coarse pore-forming agents include water-soluble polymers and surfactants. Examples of water-soluble polymers include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyacrylic acid, polyethylene glycol-polypropylene glycol block copolymers, polyvinylpyrrolidone, sodium polystyrene sulfonate, and polyallylamine hydrochloride. Examples of surfactants include cationic surfactants such as cetyltrimethylammonium chloride, anionic surfactants such as sodium dodecyl sulfate, and nonionic surfactants such as polyoxyethylene alkyl ethers.

[0059] Of the coarse pore-forming agents described above, water-soluble polymers are preferred. This is because water-soluble polymers induce a sol-gel transition accompanied by a phase separation process (typically spinodal decomposition), contributing to the formation of a co-continuous structure between the skeletal phase and the solvent phase in the gel, and consequently, the formation of coarse pores in the porous substrate. When a water-soluble polymer is used as a coarse pore-forming agent, the water-soluble polymer can be selected according to the type and reactivity of the ceramic precursor. For example, when tetraalkoxysilane is used as the ceramic precursor, polyalkylene glycol can be used as the water-soluble polymer. Alternatively, when sodium silicate or water glass is used as the ceramic precursor, polyacrylic acid can be used as the water-soluble polymer.

[0060] The reaction solution may be cooled while stirring. The cooling of the reaction solution can be carried out so that the temperature of the reaction solution is at a temperature that facilitates the sol-gel transition accompanied by a phase separation process (typically spinodal decomposition), for example, below 60°C. The lower limit of the temperature is such that the reaction solution does not freeze, for example, about 1°C. The reaction solution becomes sol-like as the hydrolysis and polycondensation reactions proceed. If the ceramic precursor does not have hydrolyzable functional groups (for example, if the ceramic precursor is sodium silicate or water glass), the hydrolysis reaction does not occur, and the reaction solution becomes sol-like as the polycondensation reaction proceeds.

[0061] In the gel manufacturing process of the sol-gel method, the sol obtained in the sol manufacturing process is added to a molding mold (a mold for molding the gel into a desired shape) as needed, and then heated to the gelation temperature to produce a polymetalloxane gel. In the gel manufacturing process, hydrolysis and polycondensation reactions proceed further to form a metalloxane polymer, and a sol-gel transition accompanied by a phase separation process (typically spinodal decomposition) is induced to produce a polymetalloxane gel (wet gel), i.e., the first gel. The produced first gel has a co-continuous structure of a skeletal phase and a solvent phase. The skeletal phase is rich in metalloxane polymers produced by hydrolysis and polycondensation reactions, and the solvent phase is rich in solvent. The skeletal phase and the solvent phase each have a continuous three-dimensional network structure and are intertwined with each other, thereby forming the co-continuous structure of the skeletal phase and the solvent phase.

[0062] The solvent phase in the first gel is a region that can serve as the starting point for the formation of coarse pores in the porous substrate when the gel is calcined in step (c) described later to obtain the porous substrate. The size of the coarse pores can be controlled by adjusting the rate of the phase separation process (typically spinodal decomposition) in step (a). The rate of the phase separation process can be adjusted, for example, by appropriately selecting the types of ceramic precursor, coarse pore-forming agent and catalyst, or by controlling the viscosity of the reaction solution.

[0063] The gelation temperature is preferably 20°C or higher, and more preferably 25°C or higher, from the viewpoint of appropriately forming a co-continuous structure between the skeletal phase and the solvent phase in the gel. From a similar viewpoint, the gelation temperature is preferably 80°C or lower, and more preferably 40°C or lower. Considering the above, the gelation temperature is preferably 20°C to 80°C, and more preferably 25°C to 40°C. The gelation time is preferably 10 minutes or more. The upper limit of this time is not particularly limited, but from the viewpoint of manufacturing efficiency, it is preferably 24 hours or less.

[0064] Once the first gel is obtained, it can be washed as needed. For example, when sodium silicate or water glass is used as the ceramic precursor, washing the first gel is preferable from the viewpoint of removing any remaining alkali metals from the first gel and successfully forming pores in step (b) described later. There are no particular restrictions on the method of washing the first gel. For example, the first gel can be immersed in a washing solution and left to stand for a predetermined time. Examples of washing solutions used for washing include water, organic solvents, mixed solvents of water and organic solvents, and aqueous solutions containing acids or bases.

[0065] For example, if the first gel contains alkali metals due to the use of sodium silicate or water glass as a ceramic precursor, it is preferable to wash the gel until the concentration of alkali metals in the first gel after washing is 1000 ppm or less, more preferably 750 ppm or less, even more preferably 500 ppm or less, even more preferably 100 ppm or less, and particularly preferably 0 ppm. Having the concentration of alkali metals in the first gel after washing within this range allows for the successful formation of pores in step (b) and improves the strength of the porous substrate obtained in step (c).

[0066] [Step (b)] Once the first gel is manufactured, the first gel is then subjected to step (b). Step (b) is a step in which pores are formed in the framework of the first gel manufactured in step (a).

[0067] Micropore-forming agents contribute to the formation of micropores in porous substrates. Micropore-forming agents have the effect of forming micropores in the gel skeleton. The micropores formed in the gel skeleton become micropores in the porous substrate. As a micropore-forming agent having such an effect, alkalis can be used, for example. Alkalis that can be used as micropore-forming agents can be selected from, for example, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide and cesium hydroxide; alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate and cesium carbonate; alkali metal bicarbonates such as sodium bicarbonate and potassium bicarbonate; alkaline earth metal hydroxides such as calcium hydroxide; alkaline earth metal carbonates such as calcium carbonate; alkaline earth metal bicarbonates such as calcium bicarbonate; ammonia; ammonium carbonate; ammonium bicarbonate; metal alkoxides such as sodium methoxy, potassium methoxy, sodium ethoxy, potassium ethoxy and tert-butoxysodium. These alkalis can be used individually or in combination of two or more. Of these, from the viewpoint of efficiently forming micropores, as well as from the viewpoint of availability and handling, the micropore-forming agent is preferably one or more selected from alkali metal hydroxides and alkaline earth metal hydroxides, more preferably one or more selected from alkali metal hydroxides, and even more preferably sodium hydroxide.

[0068] Once the micropore-forming agent is prepared, the first gel and the micropore-forming agent are mixed and impregnated. This replaces all or most of the water in the first gel with the micropore-forming agent. In this manufacturing method, the gel is separated from the micropore-forming agent. In the following description, the impregnated first gel will also be referred to as the "second gel" for convenience.

[0069] There are no particular restrictions on the impregnation method. For example, it can be carried out by immersing the first gel in a reaction solution containing a micropore-forming agent, or by dropping, coating, or spraying the reaction solution containing the micropore-forming agent onto the first gel. The impregnation treatment may be carried out by combining two or more methods. In any case, the residue of the reaction solution after separating the second gel, as well as the residue of the reaction solution that was not dropped, coated, or sprayed, can be used for another new impregnation treatment.

[0070] In any method used, using an aqueous solvent as the solvent for the reaction solution is preferable from the viewpoint of successfully forming pores in the framework of the first gel. Examples of aqueous solvents include water, hydrophilic organic solvents, and mixed solvents of water and hydrophilic organic solvents. Examples of hydrophilic organic solvents include lower alcohols having 1 to 5 carbon atoms such as methyl alcohol, ethyl alcohol, n-propanol, and 2-propanol; lower aliphatic ketones such as acetone and methyl ethyl ketone; and polyhydric alcohols having 2 to 5 carbon atoms such as 1,3-butylene glycol, propylene glycol, and glycerin. One hydrophilic organic solvent may be used alone, or two or more hydrophilic organic solvents may be used in combination. From the viewpoint of ease of handling, the aqueous solvent is preferably one or more selected from water and mixed solvents of water and hydrophilic organic solvents, and is more preferably water.

[0071] In the reaction solution, the concentration of the micropore-forming agent is preferably within a predetermined range. When alkali is used as the micropore-forming agent, from the viewpoint of successfully forming pores in the framework of the first gel, the concentration of alkali in the reaction solution is preferably 0.01 mol / L or higher, more preferably 0.05 mol / L or higher, and even more preferably 0.10 mol / L or higher. From a similar viewpoint, the concentration of alkali in the reaction solution is preferably 10.00 mol / L or lower, more preferably 5.00 mol / L or lower, and even more preferably 1.00 mol / L or lower.

[0072] When the first gel is immersed in the reaction solution for impregnation, the immersion time is preferably 10 minutes or more, more preferably 20 minutes or more, and even more preferably 30 minutes or more. The upper limit of the immersion time is not particularly limited, but from the viewpoint of manufacturing efficiency, it is, for example, 200 minutes or less.

[0073] When impregnating the first gel by dropping, coating, or spraying the reaction solution, the amount of the reaction solution dropped, coated, or sprayed should be adjusted so that a sufficient amount of the reaction solution is included to form pores in the framework of the first gel.

[0074] After impregnation treatment is performed on the first gel, the resulting second gel is separated. The second gel is impregnated with a sufficient amount of reaction solution to form pores in the gel's framework. The degree of impregnation with the reaction solution can be evaluated, for example, by the mass ratio of the gel before impregnation treatment to the gel after impregnation treatment.

[0075] Once the second gel is obtained, it is then heated in a gas. This creates pores in the framework of the second gel. In this manufacturing method, the second gel is heated while it is in a gas. That is, the second gel is separated from the reaction solution, and after the separated second gel is in a gas, the heat treatment is performed on the second gel. Embodiments in which the second gel is in a liquid during the heat treatment are not included in step (b). Conventionally, when heat treatment of a gel in a liquid (e.g., reflux heating), the entire solution, including the solution portion that does not actually contribute to the reaction (and therefore does not need to be heated), must be heated, resulting in low energy efficiency. In contrast, in step (b), because the heat treatment of the gel is performed in a gas, the reaction solution contained in the second gel (i.e., the reaction solution that actually contributes to the reaction) is heated, resulting in high energy efficiency. In addition, since this manufacturing method does not require an excessive amount of reaction solution, it is possible to suppress the disappearance of the gel due to excessive dissolution of the gel framework by the reaction solution. Furthermore, performing the heat treatment in a gaseous state is preferable from the viewpoint of enhancing the effect of the micropore-forming agent contained in the second gel. This is because performing the heat treatment in a gaseous state allows the reaction to proceed at a higher temperature compared to, for example, performing the heat treatment in a liquid state. This means that large pores are formed in the gel's framework as the gel's framework is significantly eroded by the micropore-forming agent.

[0076] In this manufacturing method, the heat treatment of the second gel is preferably carried out with the second gel contained in a container of any shape. As the container, for example, a gas barrier container and a pressure-resistant container such as an autoclave with a liner can be used. When an autoclave with a liner is used, the heat treatment of the second gel is carried out with the second gel contained in the liner. In this case, the atmosphere inside the liner becomes the atmosphere in which the heat treatment of the second gel is carried out. As the material of the liner, for example, a heat-resistant material such as polytetrafluoroethylene (PTFE) can be used. As the material of the gas barrier container, for example, plastic, metal and glass can be used. As the material of the plastic, for example, polyethylene, polypropylene, polyvinylidene chloride, ethylene vinyl alcohol copolymer, polyacrylonitrile and polyamide can be used.

[0077] In this manufacturing method, the heat treatment of the second gel is preferably carried out in a gaseous environment. That is, the heat treatment of the second gel is preferably carried out in an environment filled with gas (hereinafter also referred to as "atmosphere"). When the heat treatment of the second gel is carried out with the second gel contained in any container, the atmosphere inside the container corresponds to the above-mentioned atmosphere. Examples of atmospheres include oxidizing atmospheres and inert atmospheres. An oxidizing atmosphere is an atmosphere containing one or more oxidizing gases. In addition to one or more oxidizing gases, an oxidizing atmosphere may also contain one or more other gases (for example, one or more inert gases). An inert atmosphere is an atmosphere composed of one or more inert gases. Examples of oxidizing gases include air (atmosphere), oxygen, water vapor, and mixtures of two or more of these. Examples of inert gases include nitrogen gas, carbon dioxide gas, argon gas, and mixtures of two or more of these.

[0078] The heat treatment of the second gel may be carried out while humidifying the second gel. For example, the heat treatment of the second gel may be carried out while supplying water vapor to the second gel, or the heat treatment of the second gel may be carried out with water present in the container containing the second gel (provided that the water is not in contact with the second gel).

[0079] In the heat treatment of the second gel, the heating temperature is preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. Furthermore, the heating temperature is preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 200°C or lower. Considering the above, the heating temperature is preferably 50°C or higher and 250°C or lower, more preferably 70°C or higher and 230°C or lower, and even more preferably 80°C or higher and 200°C or lower. The heating time is preferably 1 hour or more. Furthermore, the heating time is preferably 80 hours or less, and even more preferably 72 hours or less. Considering the above, the heating time is preferably 1 hour or more and 80 hours or less, and even more preferably 1 hour or more and 72 hours or less.

[0080] The heat treatment of the second gel is preferably carried out under conditions that maintain the second gel's presence of the reaction solution. In one embodiment, the heat treatment of the second gel is carried out with the second gel contained in a sealed container (hereinafter sometimes referred to as a "sealed container"). For example, the container containing the second gel can be sealed by placing a sealed lid over it. Specific examples of the material of the sealed lid are the same as the specific examples of the material of the container.

[0081] In another embodiment, the heat treatment of the second gel is performed with the second gel contained in an open container (hereinafter sometimes referred to as the "open container"). For example, the container can be made open by not covering the container containing the second gel, or by covering the container containing the second gel with a lid having holes. The holes in the lid function as holes for releasing vapor from inside the container. Examples of lids with holes include airtight lids with holes and porous lids (e.g., paper).

[0082] Furthermore, the heat treatment of the second gel can be carried out, for example, using a heating furnace. The type of heating furnace is not particularly limited, and examples of heating furnaces include kilns and belt furnaces.

[0083] In this way, pores are formed in the gel's framework.

[0084] [Step (c)] Once pores have formed in the first gel, the first gel is then subjected to step (c). Step (c) is a process in which the first gel subjected to step (b) is washed and / or dried as necessary, and then calcined to produce a porous substrate.

[0085] The description of the washing method and washing solution is the same as described above. There are no particular restrictions on the drying method of the first gel. Examples include natural drying, heat drying, drying using a low surface tension solvent, drying by freeze-sublimation, and supercritical drying.

[0086] Subsequently, the first gel is fired. This removes any remaining water from the first gel, resulting in a porous substrate. The firing temperature is preferably higher than the heating temperature in step (b). Specifically, from the viewpoint of sufficiently removing the water contained in the first gel, the difference between the firing temperature in step (c) and the heating temperature in step (b) (i.e., [firing temperature in step (c)] - [heating temperature in step (b)]) is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher. Furthermore, from the viewpoint of suppressing pore blockage caused by sintering, the difference between the firing temperature in step (c) and the heating temperature in step (b) is preferably 700°C or lower, more preferably 600°C or lower, and even more preferably 500°C or lower. The firing time can be appropriately selected according to the firing temperature. For example, when firing is preferably at 200°C to 700°C, and more preferably at 300°C to 650°C, the firing time is preferably 3 hours to 12 hours. Firing is usually carried out in an air atmosphere.

[0087] The porous substrate (ceramic monolith) obtained in this manner has a co-continuous structure formed by a ceramic skeleton containing micropores and coarse pores. The ceramic skeleton of the porous substrate is formed from the skeletal phase of the first gel, and the coarse pores of the porous substrate are formed from the solvent phase of the first gel. The ceramic monolith may be, for example, a silica monolith, an alumina monolith, a tin oxide monolith, a ceria monolith, a titania monolith, or a zirconia monolith. These ceramic monoliths each have, in order, a silica skeleton, an alumina skeleton, a tin oxide skeleton, a ceria skeleton, a titania skeleton, and a zirconia skeleton as ceramic skeletons containing micropores, and have a co-continuous structure formed by a ceramic skeleton containing micropores and coarse pores.

[0088] Once a porous substrate is obtained, it can be subjected to molding, pulverization, or other treatments as needed. Molding and pulverization can be carried out according to conventional methods.

[0089] [Step (d)] Once the porous substrate is obtained, the porous substrate is then subjected to step (d). Step (d) is a step in which an amino compound is supported on the porous substrate produced in step (c).

[0090] There are no particular restrictions on the method of supporting the amino compound on a porous substrate. The amino compound may be chemically bonded to the porous substrate or non-chemically bonded. There are no particular restrictions on the method of chemical bonding modification. For example, a method can be used in which a silane coupling agent having a functional group containing a nitrogen element (for example, a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group) is reacted with a functional group (for example, a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group) on the surface of the porous substrate to chemically fix the silane coupling agent to the surface of the porous substrate. There are no particular restrictions on the method of non-chemical bonding modification either. For example, an amino compound may be mixed with a solvent compatible therewith to prepare a solution, and this solution may be mixed with the porous substrate to allow the solution to penetrate into the pores of the porous substrate. Then, the solvent in the solution containing the porous substrate may be removed by vacuum distillation and heated and dried to leave the amino compound in the pores of the porous substrate. Another method of non-chemical bonding modification involves, for example, placing an amino compound and a porous substrate in an autoclave with them separated, then evacuating the autoclave and filling it with the vapor of the amino compound to introduce the amino compound into the pores of the porous substrate.

[0091] Supporting a predetermined amount of amino compounds on a porous substrate is preferable from the viewpoint of successfully obtaining an amino compound-supported porous substrate in which water adsorption is suppressed more than in conventional methods. From this viewpoint, it is preferable to support the amino compounds so that the ratio of the mass of the amino compounds to the mass of Si elements in the porous substrate (amino compound / Si ratio) is 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. From a similar viewpoint, it is preferable to support the amino compounds so that the amino compound / Si ratio is 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. When supporting amino compounds by chemical bonding modification, the above-mentioned amino compound / Si charging ratio is the same value in the amino compound-supported porous substrate of the present invention.

[0092] As described above, the amino compound-supported porous substrate of the present invention can be obtained.

[0093] The amino compound-supported porous substrate of the present invention can be used for the adsorption of various gases by taking advantage of the properties of the amino compound supported thereon. In particular, the amino compound-supported porous substrate of the present invention can be used as an adsorbent for acidic gases such as carbon dioxide, nitrogen oxides, and sulfur oxides, utilizing chemiadsorption by amino groups. In particular, the amino compound-supported porous substrate of the present invention has the advantage that, due to the large pores of the porous substrate, the ratio of amino groups contributing to gas adsorption capacity is high relative to the amount of supported amino compound. Therefore, the amino compound-supported porous substrate has the advantage that the target gas and pressure conditions can be selected from a wide range during use.

[0094] Acidic gases such as carbon dioxide, nitrogen oxides, and sulfur oxides adsorbed on the amino compound-supported porous substrate of the present invention are desorbed by heating the amino compound-supported porous substrate. The desorbed carbon dioxide can be used, for example, as a raw material for the synthesis of various organic compounds, specifically as a raw material for the synthesis of methane, propylene, and gasoline. Alternatively, the amino compound-supported porous substrate with adsorbed carbon dioxide can be stored for a long period in a storage facility. Furthermore, the desorbed nitrogen oxides can be used, for example, as a raw material for the synthesis of nitric acid. The desorbed sulfur oxides can be used, for example, as a raw material for the synthesis of hydrogen sulfide and sulfuric acid.

[0095] Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments.

[0096] With regard to the above embodiments, the following amino compound-supported porous substrates, as well as an acidic gas adsorbent and a carbon dioxide adsorbent are further disclosed. [1] An amino compound-supported porous substrate having a co-continuous structure formed by a framework containing micropores and coarse pores, and an amino compound supported in at least some of the pores of the porous substrate, wherein the most frequent pore size of the coarse pores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion is 0.5 μm to 10.0 μm, the pore volume of the coarse pores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion is 0.40 mL / mL to 0.95 mL / mL per unit volume of the porous substrate, and the most frequent pore size of the micropores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion is 50.0 nm to less than 500.0 nm [1] The porous substrate is an amino compound-supported porous substrate in which the pore volume of the micropores measured by mercury intrusion in the range of pore diameter 2.0 nm to 500.0 μm is 0.05 mL / mL or more and 0.50 mL / mL or less per unit volume of the porous substrate. [2] The amino compound-supported porous substrate according to [1], wherein the amount of amino groups contained in the amino compound-supported porous substrate is 1.0 mmol / mL or more and 20.0 mmol / mL or less per unit volume of the amino compound-supported porous substrate. [3] The BET specific surface area of ​​the porous substrate is 20 m². ２ / g or more 100m ２ [1] or [2] A porous substrate supporting an amino compound, wherein the amount is less than or equal to g / g. [4] A porous substrate supporting an amino compound, wherein the bulk density of the porous substrate is 0.10 g / mL or more and 0.50 g / mL or less, according to any one of [1] to [3]. [5] An acidic gas adsorbent comprising the porous substrate supporting an amino compound, according to any one of [1] to [4]. [6] A carbon dioxide adsorbent comprising the porous substrate supporting an amino compound, according to any one of [1] to [4].

[0097] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%".

[0098] [Manufacturing Examples 1 to 3] [Process (a)] Water was placed in a container (150 mL stainless steel can), and polyacrylic acid (Fujifilm Wako Pure Chemical Industries) with a mass-average molecular weight of 25,000 (hereinafter referred to as "HPAA") was dissolved in the water. Then concentrated nitric acid was added and the mixture was stirred. Water glass (sodium silicate concentration: approximately 38%) was added to the resulting solution and stirred to obtain a homogeneous sol. The composition of the preparation was water:concentrated nitric acid:HPAA:water glass = 97:37:6.5:55 by mass ratio. The sol was allowed to stand at 30°C for 1 hour to gel and obtain a polysiloxane gel. The obtained polysiloxane gel was pulverized and classified using a sieve with a mesh size of 850 μm to obtain pulverized polysiloxane gel with a particle size of 1 to 2 cm remaining on the sieve. The obtained pulverized polysiloxane gel was washed with water until the Na concentration of the washing solution reached 500 ppm, and then immersed in water for 24 hours. After immersion, the gel was collected using a sieve to remove excess liquid adhering to the gel, thereby obtaining a first gel having a co-continuous structure formed by the skeletal phase and the solvent phase. No heat treatment was performed on the first gel. [Step (b)] 91.89 g of alkaline solution was added to a polypropylene container, then 67.06 g of the first gel was added, and the first gel was immersed in the alkaline solution. By immersion at room temperature for 30 minutes, the first gel was impregnated with the alkaline solution, and a second gel was obtained. As the alkaline solution, an aqueous sodium hydroxide solution of the concentrations shown in Table 1 was used. The second gel was collected from the polypropylene container and left to stand in an autoclave. The second gel in the autoclave was heated under the conditions shown in Table 1. [Step (c)] After heating, the second gel was washed with water and then dried using a drying oven. The dried second gel was calcined at 600°C for 3 hours in an air atmosphere to obtain a porous substrate (silica monolith). Observation of the structure of the obtained porous substrate using a SEM (JEOL JSM-7900F) confirmed that the porous substrate had a co-continuous structure of a silica framework with micropores and coarse pores formed by the silica framework.

[0099] [Manufacturing Example 4] The porous substrate in this manufacturing example was prepared by the manufacturing method described in WO2022 / 163831. 1912 g of polyethylene glycol 10000, 1890 g of urea, 12.6 g of acetic acid, and 21 kg of water were added to a 100 L container and stirred at room temperature for 30 minutes to prepare an aqueous polyethylene glycol solution. The polyethylene glycol solution was delivered at a rate of 660 mL per minute and tetramethoxysilane at 330 mL per minute to a sol solution preparation system consisting of two liquid delivery pumps, a static mixer, and a cooling piping section (2°C). The mixture was mixed and cooled within the system to obtain a mixed solution. The mixed solution was collected in a stirring tank cooled to 5°C and stirred for 34 minutes. After stirring, the sol solution was delivered to a 600 mL container, a mold for forming cylindrical pellets with a diameter of 4.6 mm was added, and a polysiloxane gel was prepared by heating in a 30°C bath.

[0100] Next, the obtained polysiloxane gel was added to a reaction vessel containing 1250 mL of 3.0 mol / L urea solution, and heated under reflux at 98°C for 12 hours.

[0101] After the reaction was complete, the obtained polysiloxane gel was washed with water and dried in a dryer set to 80°C for 24 hours. After drying, it was calcined at 600°C for 5 hours in an air atmosphere to obtain a cylindrical porous substrate with a diameter of 4.6 mm. The obtained porous substrate was crushed and classified using a sieve with a mesh size of 850 μm and a sieve with a mesh size of 1.18 mm to obtain porous substrates with particle sizes ranging from 850 μm to 1.18 mm. When the structure of the obtained porous substrate was observed using a SEM (JEOL JSM-7900F), it was confirmed that it had a co-continuous structure of a silica skeleton with micropores and coarse pores formed by the silica skeleton.

[0102] [Production Examples 5 and 6] A porous substrate was obtained in the same manner as in Production Example 1, except that in step (a), the obtained polysiloxane gel was pulverized and classified using a sieve with a mesh size of 850 μm to obtain pulverized polysiloxane gel with a particle size of 850 μm or less remaining under the sieve, and in step (b), the second gel in the autoclave was heated under the conditions shown in Table 1.

[0103] [Example 1] [Step (d)] A porous substrate obtained in Production Example 1 was used as the base material. Polyethyleneimine 600 (mass-average molecular weight 600) was used as the amino compound. 0.8 g of polyethyleneimine 600 was dissolved in 17 mL of deionized water, and then 0.8 g of the porous substrate was added. At this time, the amino compound / Si charging ratio was as shown in Table 2. The mixed solution obtained by letting these stand overnight was reduced to 10 kPa or less at 80°C to remove the deionized water, and the amino compound was supported in the pores of the porous substrate (non-chemical bonding modification) to obtain the target amino compound-supported porous substrate.

[0104] [Example 2] Polyethyleneimine 600 (mass-average molecular weight 600) having multiple isopropyl groups was used as the amino compound. 1.6 g of polyethyleneimine 600 was dissolved in 18 mL of deionized water, and then 0.8 g of the porous substrate was added. Except for these steps, the porous substrate supporting the target amino compound was obtained in the same manner as in Example 1.

[0105] [Example 3] As the base material, the porous base material obtained in Production Example 2 was used. Otherwise, the target amino compound-supported porous base material was obtained in the same manner as in Example 1.

[0106] [Example 4] As the base material, the porous base material obtained in Production Example 2 was used. Otherwise, the target amino compound-supported porous base material was obtained in the same manner as in Example 2.

[0107] [Example 5] As the base material, the porous base material obtained in Production Example 3 was used. Except for these differences, the target amino compound-supported porous base material was obtained in the same manner as in Example 2.

[0108] [Examples 6 and 7] The porous substrate obtained in Production Example 5 was used as the base material. The amino compound / Si charging ratio was set to the values ​​shown in Table 2. Except for these differences, the target amino compound-supported porous substrate was obtained in the same manner as in Example 1.

[0109] [Example 8] As the base material, the porous base material obtained in Production Example 5 was used. In addition, the amino compound / Si charging ratio was changed to the values ​​shown in Table 2. Except for these changes, the target amino compound-supported porous base material was obtained in the same manner as in Example 2.

[0110] [Examples 9 to 11] The porous substrate obtained in Production Example 6 was used as the base material. The amino compound / Si charging ratio was set to the values ​​shown in Table 2. Except for these, the target amino compound-supported porous substrate was obtained in the same manner as in Example 1.

[0111] [Examples 12 to 14] The porous substrate obtained in Production Example 6 was used as the base material. The amino compound / Si charging ratio was set to the values ​​shown in Table 2. Except for these, the target amino compound-supported porous substrate was obtained in the same manner as in Example 2.

[0112] [Comparative Example 1] As the base material, the porous base material obtained in Production Example 4 was used. Except for this, the target amino compound-supported porous base material was obtained in the same manner as in Example 1.

[0113] [Evaluation] SEM images of the porous substrate obtained in Production Example 1 are shown in Figures 2(a) and 2(b) below. Figure 2(a) is an SEM image of the porous substrate observed at 2000x magnification. Figure 2(b) is an SEM image of the porous substrate observed at 20000x magnification. In Figure 2(a), the black circular areas are coarse pores. In Figure 2(b), the black spots are micropores. For the amino compounds used in Examples 2, 4, 5, 8 and 12 to 14, the value R, obtained by dividing the number of substituents in the amino compound by the number of nitrogen atoms in the amino compound, was calculated using the following method. For the porous substrates used in the examples and comparative examples, the most frequent pore diameter of micropores and coarse pores, the pore volume of micropores and coarse pores, the total pore volume, the BET specific surface area, and the bulk density were measured using the following method. In addition, the value of Ds / Dr was calculated based on the value of the most frequent pore diameter. For the amino compound-supported porous substrates obtained in the examples and comparative examples, the pore volume of micropores and coarse pores, the total pore volume, the BET specific surface area, and the bulk density were measured by the following methods. For the amino compound-supported porous substrates obtained in the examples and comparative examples, the amount of amino groups, the amount of carbon dioxide adsorbed, the amount of water adsorbed, and the remaining ratio of amino compounds were measured by the following methods. These results are shown in Tables 1 and 2 below. In Table 2, "-" indicates that the evaluation was not performed.

[0114] [Value R] For polyethyleneimine 600 having isopropyl groups used in Examples 2, 4, 5, 8 and 12 to 14, an NMR spectrometer (Bruker AVANCE NEO600) was used under the following conditions: １¹H-NMR measurements were performed to obtain NMR spectra. From the obtained NMR spectra, the integral values ​​of signals mainly corresponding to the main chain other than the methyl group (around 2.4 ppm to 2.9 ppm) and the integral value of the signal corresponding to the methyl group (around 1.1 ppm) were calculated. Here, "signals mainly corresponding to the main chain other than the methyl group" refers to the signals corresponding to the ethylene group linking the two nitrogen atoms and the methine group in the isopropyl group. When calculating the integral values, for the purpose of normalization, the integral value of the signal corresponding to the methyl group (around 1.1 ppm) was set to 6, which is the number of protons in the methyl group of the isopropyl group, and the integral value of signals mainly corresponding to the main chain other than the methyl group (around 2.4 ppm to 2.9 ppm) was calculated. The number of nitrogen atoms N was calculated by subtracting the integral value of the signal corresponding to the methine group (1) from the integral value of the signal mainly corresponding to the main chain other than the methyl group (around 2.4 ppm to 2.9 ppm), and then dividing this value by 4, which is the number of protons in the repeating unit of polyethyleneimine. The value R was calculated by dividing the number of substituents contained in polyethyleneimine by the number of nitrogen atoms N. As mentioned above, for the purpose of normalization, the integral value of the signal corresponding to the methyl group (around 1.1 ppm) was set to 6, which is the number of protons in the methyl group of the isopropyl group, so the number of such substituents is 1. As a result of the calculation, the value R was 0.2 for polyethyleneimine 600 having isopropyl groups in Examples 2, 4, 5, 8 and 12 to 14. <Measurement Conditions> ・Magnetic field: 14.1 T (1H 600.13 MHz) ・NMR probe: 1.3 mm MAS probe ・Sample rotation speed: 60 kHz ・Standard sample for chemical shift value and radio wave intensity: Adamantane ・Reference for chemical shift value: The chemical shift value of the maximum point of the 1H NMR spectrum of adamantane was set to 1.91 ppm. ・Measurement method: Single pulse method ・Spectrum center (O1 value - SR value (chemical shift notation)): 1.91 ppm ・Radio wave pulse intensity: The value was set to the pulse width of 2.5 μs that maximizes the peak of adamantane when the spectrum center is 1.91 ppm.- Radio wave pulse width: 2.5 μs - Measurement interval: 5 μs (DW = 2.5 μs in the software mentioned above) - Number of measurement points: 16,384 points (TD = 32,768 in the software mentioned above) - Number of spectral points (SI in the software mentioned above): 32,768 points - Repeat time (D1 in the software mentioned above): 8 seconds - Number of integrations (NS in the software mentioned above): 16 times.

[0115] [Most frequent pore diameter of micropores and coarse pores, pore volume of micropores and coarse pores, and total pore volume] The most frequent pore diameter of micropores and coarse pores, the pore volume of micropores and coarse pores, and the total pore volume were measured using a mercury porosimeter (AutoPore IV 9520, Micromeritics) by the mercury intrusion method. In the mercury intrusion method, pressure was applied to the pores of the sample to infiltrate mercury, and the pore volume per unit volume and specific surface area were calculated from the pressure and the amount of mercury injected. Subsequently, the pore diameter was calculated from the relationship between the pore volume and specific surface area assuming the pores are cylindrical. In this specification, the analysis was performed on pores with a diameter of 2.0 nm to 500.0 μm. The pore volume was calculated by multiplying the pore volume calculated by the mercury intrusion method by the bulk density. Furthermore, pores originating from peaks with a peak volume of less than 0.01 mL / g in the pore distribution diagram obtained by the mercury intrusion method were not used in the calculation, taking into consideration the measurement accuracy. <Measurement conditions> "Mercury parameters; forward contact angle: 130.0 degrees, backward contact angle: 130.0 degrees, surface tension: 485.0 mN / m (485.0 dynes / cm), mercury density: 13.5335 g / mL", "Low pressure parameters; exhaust pressure: 50 μmHg, exhaust time: 5.0 min, mercury injection pressure: 0.0035 MPa, equilibrium time: 10 seconds", "High pressure parameters; equilibrium time: 10 seconds", "Intrusion volume: adjusted to be between 25% and 90%", "Measurement environment: 20°C". <Measurement procedure> (1) Weigh approximately 0.5 g of the sample and place it in the sample cell, then input the weighed value. (2) Measure the pressure in the low-pressure section in the range of 0.0048 to 0.2068 MPa. (3) Measure the pressure in the high-pressure section in the range of 0.2068 to 255.1060 MPa. Procedures (2) and (3) were performed automatically using the software attached to the device. The most frequent pore diameter and pore volume of the micropores and coarse pores of the porous substrate can also be calculated from an amino compound-supported porous substrate that has undergone the following pretreatment. Specifically, an amino compound-supported porous substrate is heated at 600°C for 5 hours in an atmospheric environment to obtain a porous substrate with an unmodified surface from which the amino compound has dissociated from the surface of the porous substrate.By analyzing this data, the most frequent pore diameter and pore volume of the micropores and coarse pores in the porous substrate can be calculated.

[0116] [BET Specific Surface Area] The BET specific surface area was measured by the nitrogen adsorption method. As a pretreatment, both the porous substrate and the amino compound-supported porous substrate were heated at 400°C for 3 hours under reduced pressure of 20 Pa. A gas adsorption analyzer (Micromeritics 3Flex) was used for nitrogen adsorption and desorption measurements, and the BET (Brunauer-Emmett-Teller) method was used to calculate the BET specific surface area from the adsorption isotherm at liquid nitrogen temperature (77 K). Note that the BET specific surface area can also be calculated from the pretreated amino compound-supported porous substrate, similar to the "most frequent pore diameter of micropores and coarse pores, pore volume of micropores and coarse pores, and total pore volume" described above.

[0117] [Bulk Density] The bulk density was measured using the following method. Specifically, after step (3) in the above-mentioned "Most frequent pore diameter of micropores and coarse pores, pore volume of micropores and coarse pores, and total pore volume," step (4) was performed to calculate the pore diameter distribution from the mercury injection pressure and mercury injection amount. Step (4) was performed automatically using the software attached to the instrument. The bulk density was calculated from the pore diameter distribution using the attached software. The bulk density was referenced from "Bulk Density at 0.0035 MPa" in the software.

[0118] [Amount of Amino Groups] For the amino compound-supported porous substrates of Example 2, Example 4, and Comparative Example 1, the amount of amino groups contained in the amino compound-supported porous substrate per unit mass was quantified using an oxygen-nitrogen-hydrogen analyzer (ONH836, manufactured by LECO Japan LLC). The amount of amino groups obtained was multiplied by the bulk density of the porous substrate (after amino compound support) to calculate the amount of amino groups per unit volume of the porous substrate.

[0119] [Carbon Dioxide Adsorption Amount] The amount of carbon dioxide adsorbed was measured using an adsorption amount / adsorption rate measuring device (BELCAT II, ​​Microtrac-Bel). 0.1 g of a porous substrate supported with an amino compound was placed in a sample cell and pretreated at 100°C for 10 minutes under a helium flow of 50 sccm. After pretreatment, the temperature of the sample chamber was set to 25°C, and a 4 vol% carbon dioxide gas was flowed through at 50 sccm for 25 minutes. Then, the flow of carbon dioxide was stopped, and helium was flowed through at 50 sccm, and the temperature was raised to 100°C at a heating rate of 5°C / min and held for 15 minutes. The amount of carbon dioxide adsorbed was calculated from the peak area detected by TCD during this time.

[0120] [Water Adsorption Amount] Water adsorption amount was measured using a specific surface area and pore distribution analyzer (BELSORP MAX, Microtrac-Bel). As a pretreatment, 0.05 kg of porous substrate supported with amino compounds was heat-treated at 10 Pa, 120°C, and 30 minutes. The pre-treated porous substrate supported with amino compounds was placed in the sample cell of the BELSORP MAX, the temperature of the sample chamber was set to 25°C, and the water adsorption isotherm was obtained. Based on the adsorption isotherm, relative pressure p / p ０ The amount of water adsorption at =0.90 was calculated. Specifically, two points were selected from the adsorption isotherm, and the relative pressure p / p was calculated based on the equation of the straight line connecting the two points. ０ The amount of water adsorption at =0.90 was calculated. The two points to be selected are relative pressure p / p ０ = 1 point from the range of 0.90 + 0.05, p / p ０ A point was selected from the range of 0.90-0.05.

[0121] [Remaining Ratio of Amino Compounds] For the amino compound-supported porous substrates of Example 2 and Comparative Example 1, the amount of amino compound eluted when immersed in water was measured. First, filter paper (Advantec No. 5C) was placed in a Buchner funnel with an inner diameter of 90 mm, and 0.25 g of the amino compound-supported porous substrate (in terms of silica mass) was placed on top of it. The mass of the amino compound-supported porous substrate (in terms of silica mass) was calculated based on the dry mass of the amino compound-supported porous substrate and the amino compound / Si loading ratio. The dry mass was measured immediately after the amino compound-supported porous substrate was dried under reduced pressure at 80°C and 10 kPa or less for 12 hours or more. Next, 10 mL of pure water at 25°C was poured onto the amino compound-supported porous substrate, and the substrate was allowed to stand until no more water droplets fell, thereby wetting the amino compound-supported porous substrate. Porous substrates supporting amino compounds were moistened at 80°C and 10 kPa or less for 12 hours or more, then dried under reduced pressure, and their dry mass was measured. The remaining ratio of amino compounds after the elution test was calculated by dividing the dry weight of the amino compound-supported porous substrate after moistening by the dry mass of the amino compound-supported porous substrate before moistening. A higher remaining ratio of amino compounds indicates that the elution of amino compounds from the amino compound-supported porous substrate is suppressed.

[0122]

[0123]

[0124] As is clear from the results shown in Figures 2(a) and 2(b), the porous substrate has a co-continuous structure of a silica skeleton with micropores and coarse pores. Furthermore, as is clear from the results shown in Table 2, the amino compound-supported porous substrates of Examples 1 to 14 show suppressed water adsorption compared to Comparative Example 1. In addition, the amino compound-supported porous substrate of Example 2 shows suppressed elution of the amino compound compared to Comparative Example 1.

[0125] According to the present invention, a porous substrate supporting an amino compound is provided in which water adsorption is suppressed compared to conventional materials. Furthermore, an acidic gas adsorbent and a carbon dioxide adsorbent containing the porous substrate supporting the amino compound are also provided.

Claims

1. An amino compound-supported porous substrate comprising: a porous substrate having a co-continuous structure formed by a framework containing micropores and coarse pores; and an amino compound supported in at least some of the pores of the porous substrate, wherein the most frequent pore size of the coarse pores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion is 0.5 μm to 10.0 μm; the pore volume of the coarse pores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion is 0.40 mL / mL to 0.95 mL / mL per unit volume of the porous substrate; and the most frequent pore size of the micropores measured in the range of pore diameter 2.0 nm to 500.0 μm by mercury intrusion is 50.0 nm to less than 500.0 nm. The porous substrate is an amino compound-supported porous substrate in which the pore volume of the micropores, measured by mercury intrusion in the range of pore diameter 2.0 nm to 500.0 μm, is 0.05 mL / mL to 0.50 mL / mL per unit volume of the porous substrate.

2. The amino compound-supported porous substrate according to claim 1, wherein the amount of amino groups contained in the amino compound-supported porous substrate is 1.0 mmol / mL or more and 20.0 mmol / mL or less per unit volume of the amino compound-supported porous substrate.

3. The BET specific surface area of ​​the porous substrate is 20 m². ２ / g or more 100m ２ The porous substrate supporting an amino compound according to claim 1 or 2, wherein the amount is less than or equal to / g.

4. The porous substrate supporting an amino compound according to claim 1 or 2, wherein the bulk density of the porous substrate is 0.10 g / mL or more and 0.50 g / mL or less.

5. An acid gas adsorbent comprising an amino compound-supported porous substrate according to claim 1 or 2.

6. A carbon dioxide adsorbent comprising a porous substrate supporting an amino compound as described in claim 1 or 2.

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