Amino compound-supported porous substrate and acid gas adsorbent

Abstract

This amino compound-supporting porous substrate has: a porous substrate 1 that at least has a macropore 2; and an amino compound carried in at least a portion of the pores of the porous substrate 1. The porous substrate 1 has a total pore volume, as measured by a mercury intrusion method, of 0.55-0.95 mL / mL per unit volume of the porous absorbent. The skeleton 3 of the porous absorbent 1 preferably contains an element selected from silicon, aluminum, tin, cerium, titanium, and zirconium.

Description

[Technical field]

[0001] The present invention relates to a porous substrate supporting an amino compound, and an acidic gas adsorbent comprising the porous substrate. [Background technology]

[0002] In recent years, with the growing awareness of environmental issues, emissions of carbon dioxide, nitrogen oxides such as NO and NO2, and sulfur oxides such as SO and SO2 contained in exhaust gases have become a problem. For example, attention has been focused on technologies for separating and capturing carbon dioxide, which is one of the causes of global warming, and studies are being conducted on technologies for separating and capturing carbon dioxide emitted from thermal power plants and steelworks. One known technology for separating and capturing carbon dioxide is a method that uses a carbon dioxide adsorbent in which an amino compound is supported on a porous material.

[0003] For example, Patent Document 1 describes an amino compound-supported porous substrate for adsorbing carbon dioxide, in which a porous substrate having mesopores is exposed to an atmosphere in which the amino compound is in a gaseous state, thereby supporting the amino compound inside the mesopores. Patent Document 2 describes a carbon dioxide adsorbent that includes a gas adsorbing material containing an amino compound, a hydroxyl-containing additive containing glycerol or the like, and a porous carrier impregnated with the gas adsorbing material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-113337 A [Patent Document 2] WO2016 / 154278A1 Summary of the Invention

[0005] However, carbon dioxide adsorbents using porous substrates, particularly those using porous substrates having mesopores, have the problem that the types of compounds that can be supported are limited, and from the viewpoint of the diffusibility and flowability of gas flowing through the porous substrate, there is also the problem that the amount of amino compound that contributes to the carbon dioxide adsorption ability is small relative to the total amount of amino compound supported. Therefore, an object of the present invention is to provide an amino compound-supported porous substrate that can support various amino compounds and in which the proportion of amino compounds that contribute to the adsorption performance relative to the supported amount is higher than that of conventional adsorbents supporting the same amino compounds.

[0006] The present invention relates to a porous substrate having at least macropores, an amino compound supported in at least some of the pores of the porous substrate; An amino compound-supported porous substrate comprising: The porous substrate provides an amino compound-supporting porous substrate having a total pore volume measured by mercury intrusion porosimetry of 0.55 mL / mL or more and 0.95 mL / mL or less per unit volume of the porous substrate.

[0007] The present invention also provides an acidic gas adsorbent comprising the amino compound-supported porous substrate. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an enlarged view of a main part of a porous substrate used in the present invention. [Diagram 2] FIG. 2 is a scanning electron microscope image of the porous substrate used in the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described below based on its preferred embodiment. The present invention relates to a porous substrate carrying an amino compound. In the present invention, the amino compound is carried on at least a part of the pores of the porous substrate. Although a porous substrate carrying an amino compound is conventionally known, the amino compound-carrying porous substrate of the present invention is characterized in that it can carry a large number of types of amino compounds. In addition, the amino compound-carrying porous substrate of the present invention is characterized in that it has a higher proportion of amino compounds that contribute to the adsorption of acidic gases than conventional substrates carrying the same amino compound. For this purpose, it is advantageous for the porous substrate used in the present invention (i.e., the porous substrate before carrying the amino compound) to have the pores described below.

[0010] The porous substrate used in the present invention has a total pore volume Vt measured by mercury intrusion porosimetry, which is preferably 0.55 mL / mL or more and 0.95 mL / mL or less per unit volume of the porous substrate. Due to having such a pore volume, the porous substrate used in the present invention can support various amino compounds, and when formed into a molded body, the compressive strength is high. In addition, when an amino compound is supported on the porous substrate used in the present invention, the amount of amino groups contributing to gas adsorption can be made larger than that of conventional porous substrates. From the viewpoint of making this advantage even more prominent, the porous substrate used in the present invention has a total pore volume Vt measured by mercury intrusion porosimetry, which is more preferably 0.55 mL / mL or more and 0.90 mL / mL or less per unit volume of the porous substrate, more preferably 0.60 mL / mL or more and 0.85 mL / mL or less, and particularly preferably 0.70 mL / mL or more and 0.85 mL / mL or less.

[0011] On the other hand, the total pore volume of the amino compound-supported porous substrate of the present invention in a state in which the porous substrate supports an amino compound depends on the type of amino compound supported and the amount of amino compound supported, but the total pore volume Va measured by mercury intrusion porosimetry is preferably 0.05 mL / mL or more and 0.80 mL / mL or less per unit volume of the amino compound-supported porous substrate. By having such a pore volume, the amino compound-supported porous substrate can have both adsorption performance and diffusibility of the gas to be circulated. From the viewpoint of making this advantage more prominent, the amino compound-supported porous substrate used in the present invention has a total pore volume Va measured by mercury intrusion porosimetry, more preferably 0.10 mL / mL or more and 0.75 mL / mL or less, more preferably 0.50 mL / mL or more and 0.70 mL / mL or less per unit volume of the amino compound-supported porous substrate.

[0012] The porous substrate used in the present invention (i.e., the porous substrate before carrying the amino compound) is advantageously provided with at least macropores. This allows the amino compound-supported porous substrate of the present invention to carry various amino compounds. In addition, the amino compound-supported porous substrate of the present invention has a high proportion of amino compounds that contribute to the adsorption of acidic gases. The macropores in the porous substrate generally refer to pores having a pore diameter of 50 nm or more among the pores in the porous substrate. The porous substrate used in the present invention has a controlled distribution of the pore diameters of the macropores in the porous substrate. In detail, the most frequent pore diameter Dm of the macropores measured in the pore diameter range of 50 nm to 500 μm by mercury intrusion porosimetry is preferably 0.05 μm to 3.0 μm. Due to the macropores having such a distribution, the porous substrate used in the present invention can support various amino compounds. In addition, when an amino compound is supported on the porous substrate used in the present invention, it is possible to increase the amount of amino groups contributing to gas adsorption compared to conventional porous substrates. In order to make this advantage even more pronounced, the porous substrate used in the present invention preferably has a most frequent pore size Dm of macropores measured by mercury intrusion porosimetry in a pore size range of 50 nm or more and 500 μm or less, of 0.07 μm or more and 2.0 μm or less, and even more preferably 0.10 μm or more and 1.5 μm or less.

[0013] The porous substrate used in the present invention preferably has a controlled pore volume of macropores. In detail, the pore volume Vm of the macropores measured by mercury intrusion in a range of pore diameters of 50 nm to 500 μm is preferably 0.20 mL / mL to 0.70 mL / mL per unit volume of the porous substrate. Due to the pore volume of the macropores being in this range, the porous substrate used in the present invention can support various amino compounds, and the compressive strength when molded is high. In addition, when an amino compound is supported on the porous substrate used in the present invention, the amount of amino groups contributing to gas adsorption can be increased compared to conventional porous substrates. In order to make this advantage even more pronounced, the porous substrate used in the present invention has a pore volume Vm of macropores measured by mercury intrusion porosimetry in a pore diameter range of 50 nm or more and 500 μm or less, per unit volume of the porous substrate, which is more preferably 0.30 mL / mL or more and 0.65 mL / mL or less, and even more preferably 0.40 mL / mL or more and 0.60 mL / mL or less.

[0014] On the other hand, the pore volume Vma of the macropores in the amino compound-supported porous substrate of the present invention when the porous substrate supports the amino compound is preferably 0.01 mL / mL or more and 0.65 mL / mL or less, more preferably 0.01 mL / mL or more and 0.60 mL / mL or less, and even more preferably 0.01 mL / mL or more and 0.57 mL / mL or less per unit volume of the amino compound-supported porous substrate. The pore volume Vma of the macropores in the amino compound-supported porous substrate is in such a range, and therefore it is possible to provide both adsorption performance and diffusibility of the gas to be passed through.

[0015] The porous substrate used in the present invention preferably has mesopores in addition to the macropores described above. Mesopores generally refer to pores having a pore diameter of more than 2 nm and less than 50 nm among the pores of the porous substrate. The porous substrate used in the present invention has macropores and mesopores, which improves the gas adsorption performance and improves the amino compound support efficiency. From the viewpoint of making this advantage more prominent, the porous substrate used in the present invention preferably has a mode pore diameter Ds of mesopores measured in the range of pore diameters of more than 2.0 nm and less than 50 nm by mercury intrusion porosimetry of more than 2.0 nm and less than 50 nm, more preferably 5.0 nm or more and 30 nm or less, and even more preferably 7.0 nm or more and 20 nm or less.

[0016] The porous substrate used in the present invention preferably has a controlled pore volume of mesopores. In detail, the porous substrate used in the present invention has a pore volume Vs of mesopores measured by mercury intrusion in the range of pore diameters of more than 2.0 nm and less than 50 nm, which is preferably 0.05 mL / mL or more and 0.50 mL / mL or less per unit volume of the porous substrate. Due to the pore volume of the mesopores being in this range, the porous substrate used in the present invention can support various amino compounds, and the compressive strength when molded into a molded body is high. In addition, when an amino compound is supported on the porous substrate used in the present invention, the amount of amino groups contributing to gas adsorption can be made larger than that of conventional porous substrates. From the viewpoint of making this advantage even more remarkable, the porous substrate used in the present invention preferably has a mesopore volume Vs, measured by mercury intrusion porosimetry in the pore diameter range of more than 2.0 nm and less than 50 nm, of 0.10 mL / mL or more and 0.40 mL / mL or less, and even more preferably 0.15 mL / mL or more and 0.35 mL / mL or less.

[0017] On the other hand, the pore volume Vsa of the mesopores in the amino compound-supported porous substrate of the present invention when the porous substrate supports the amino compound is preferably 0.01 mL / mL or more and 0.30 mL / mL or less, more preferably 0.01 mL / mL or more and 0.25 mL / mL or less, and even more preferably 0.01 mL / mL or more and 0.20 mL / mL or less per unit volume of the amino compound-supported porous substrate. The pore volume Vsa of the mesopores in the amino compound-supported porous substrate in this range makes it possible to provide both adsorption performance and diffusibility of the gas to be passed through.

[0018] The pore volume per unit volume of the above-mentioned porous substrate and the amino compound-supported porous substrate can be calculated using the pore volume per unit mass measured by a conventional method and the bulk density. The bulk density can be measured, for example, by mercury intrusion porosimetry. Similarly, the amount of amino groups per unit volume of the amino compound-supporting porous substrate of the present invention described below can be calculated using the amount of amino groups per unit mass measured using a conventional method and the bulk density.

[0019] When the porous substrate used in the present invention has macropores and mesopores, the ratio of the most frequent pore size Dm of the macropores to the most frequent pore size Ds of the mesopores, Dm / Ds, is preferably from 5 to 200, since this advantageously improves the gas adsorption performance. From the viewpoint of making this advantageous effect more prominent, Dm / Ds is more preferably from 5 to 150, even more preferably from 30 to 150, even more preferably from 30 to 130, particularly preferably from 40 to 130, especially preferably from 40 to 120, and even more preferably from 50 to 120.

[0020] When the porous substrate used in the present invention has macropores and mesopores, it is preferable that the porous substrate 1 has a co-continuous structure of a skeleton 3 in which mesopores 4 are formed and macropores 2, as shown in Fig. 1. In the porous substrate 1 shown in Fig. 1, the skeleton 3 and the macropores 2 each have a continuous three-dimensional network structure and are entangled with each other, thereby forming a co-continuous structure of the skeleton 3 and the macropores 2. The fact that the porous substrate 1 has a co-continuous structure of the skeleton 3 and the macropores 2 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").

[0021] 1 refers to a portion made of the material that constitutes the porous substrate 1. The material that constitutes the porous substrate 1 may be, for example, an oxide ceramic that contains a metalloid element or a metal element. An example of the metalloid element is silicon. An example of the oxide ceramics containing silicon is silica (SiO2). Examples of metal elements include transition metal elements such as aluminum, tin, cerium, titanium, zirconium, vanadium, chromium, iron, cobalt, nickel, palladium, platinum, copper, silver, gold, and zinc. Among these, aluminum, tin, cerium, titanium, and zirconium are preferred from the viewpoint of ease of manufacturing the porous substrate 1. Examples of oxide ceramics containing aluminum, tin, cerium, titanium, or zirconium include alumina (Al2O3), tin oxide (SnO2), ceria (CeO2), titania (TiO2), and zirconia (ZrO2).

[0022] When the oxide ceramic contains silicon or a transition metal element, the oxide ceramic may further contain, in addition to silicon or a transition metal element, an element selected from alkali metal elements such as lithium and sodium, alkaline earth metal elements such as magnesium and calcium, and rare earth elements such as lanthanum, scandium, yttrium, and gadolinium.

[0023] The shape of the porous substrate used in the present invention is not particularly limited. The porous substrate may be, for example, spherical, polyhedral, columnar, or flat, or any combination thereof. When the amino compound-supported porous substrate of the present invention is used as a gas adsorbent, as described below, the porous substrate is preferably a molded body from the viewpoint of reducing pressure loss. When the porous substrate is a molded body, appropriate voids are generated between the porous substrates, and gas adsorption can be efficiently performed without excessive pressure loss. The shape of the molded body is not particularly limited. For example, the porous substrate may be a columnar, spherical, polyhedral, or flat shape, or any combination thereof, as described below.

[0024] When the porous substrate is a columnar molded body, the porous substrate may be a columnar body having a convex curved side surface, such as a circular cylinder or an elliptical cylinder. Alternatively, the porous substrate may be a polygonal column such as a square column, a hexagonal column, or an octagonal column, that is, a columnar body having a side surface composed of a plurality of flat surfaces. When the porous substrate is a columnar body, the columnar body may be partially missing. For example, the cross section of the columnar body may be a shape having a partially missing shape, such as a circle, an ellipse, or a polygon. In the case of a "columnar body", the end faces at the upper and lower ends in the height direction of the column are geometrically flat. However, in the present invention, the end faces do not have to be flat in the strict sense and may have curved portions (convex curved portions and / or concave curved portions) within the range that can be regarded as a columnar body.

[0025] When the porous substrate is a columnar molded body, its average diameter, i.e., the average diameter of the cross section of the columnar body cut in a direction perpendicular to the height direction of the columnar body, is preferably 1.5 mm or more, more preferably 2.5 mm or more, more preferably 3.0 mm or more, even more preferably 3.5 mm or more, and even more preferably 4.0 mm or more. On the other hand, the upper limit of the average diameter of the columnar body is preferably 20 mm or less, more preferably 14 mm or less, more preferably 12 mm or less, even more preferably 10 mm or less, and even more preferably 8 mm or less. By setting the average diameter of the columnar body within this range, the durability of the columnar body can be improved and the amount of amino compound supported can be increased. In addition, when the cross section of the columnar body cut in a direction perpendicular to the height direction of the columnar body is not circular, the above-mentioned average diameter means the circle-equivalent diameter for the area of ​​the cross section.

[0026] When the porous substrate is a columnar body, the aspect ratio is preferably 0.70 or more, more preferably 1.0 or more, and even more preferably 1.5 or more, from the viewpoint of improving durability. Moreover, the aspect ratio of the columnar body is preferably 10 or less, more preferably 7.0 or less, even more preferably 5.0 or less, and even more preferably 4.0 or less, from the viewpoint of workability when packed in a column. The aspect ratio of the columnar body is the value obtained by dividing the height of the columnar body 1 by the average diameter of the end face of the columnar body.

[0027] When the amino compound-supported porous substrate used in the present invention is a molded body, it is preferable that the compressive strength is 5N or more from the viewpoint of durability, regardless of its shape. From this viewpoint, the compressive strength of the porous substrate is more preferably 7N or more, and even more preferably 10N or more. From the viewpoint of durability, the higher the compressive strength of the porous substrate, the more desirable it is, and although there is no particular upper limit, it is generally 60N or less. If the compressive strength is as high as about 10N, the durability of the porous substrate is satisfactory. The method for measuring the compressive strength will be described in the examples.

[0028] The porous substrate used in the present invention is preferably produced by a method including the steps (a) to (c) described below. (a) A process for producing a polymetalloxane gel by a sol-gel method. (b) forming pores in the skeleton of the polymetalloxane gel produced in step (a); (c) A step of calcining the polymetalloxane gel subjected to the step (b), after washing and / or drying as necessary, to produce a porous substrate. Each step will be described below.

[0029] <Process (a)> In step (a), a polymetalloxane gel is produced by a sol-gel method. Polymetalloxane is an inorganic polymer with a metalloxane bond as the main chain. The metalloxane bond is a bond between a metalloid or metal element and an oxygen atom, i.e., an MO bond (M represents a metalloid or metal element).

[0030] Examples of metalloid elements represented by M include silicon. Examples of metal elements represented by M include transition metal elements such as aluminum, tin, cerium, titanium, zirconium, vanadium, chromium, iron, cobalt, nickel, palladium, platinum, copper, silver, gold, and zinc. From the viewpoint of ease of manufacturing the porous substrate, it is preferable that the metal element represented by M is at least one of aluminum, tin, cerium, titanium, and zirconium.

[0031] The sol-gel method can be carried out according to a conventional method. An example of the sol-gel method is as follows. The sol-gel process includes a sol preparation step and a gel preparation step. In the sol preparation process, a reaction solution containing a ceramic precursor, a catalyst, and a macropore-forming agent is mixed to prepare a sol. The ceramic precursor is not particularly limited in type as long as it can form a polymetalloxane gel. The ceramic precursor may be, for example, a semimetal compound (e.g., silicon compound) having a hydroxyl group and / or a hydrolyzable functional group, a metal compound (e.g., aluminum compound, tin compound, cerium compound, titanium compound, zirconium compound, etc.) having a hydroxyl group and / or a hydrolyzable functional group, etc. The total number of hydroxyl groups and hydrolyzable functional groups in the ceramic precursor may be 1 or 2, but from the viewpoint of producing a polymetalloxane gel having a highly crosslinked structure by metalloxane bonds (MO bonds), it is preferably 3 or more, and more preferably 4. When the ceramic precursor has two or more hydrolyzable functional groups, the types of the two or more hydrolyzable functional groups may be the same or different.

[0032] The hydrolyzable functional group is a functional group that is converted to a hydroxy group by hydrolysis. Examples of the hydrolyzable functional group include an alkoxy group, an acetoxy group, a halide group, and a hydride group, and an alkoxy group is preferred. The alkoxy group is preferably an alkoxy group having 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 5 carbon atoms, and even more preferably a methoxy group, an ethoxy group, or a propyl group. The alkoxy group may be linear or branched.

[0033] The silicon compound having a hydroxyl group and / or a hydrolyzable functional group is preferably an alkoxysilane. Examples of the alkoxysilane include tetraalkoxysilane, trialkoxysilane, dialkoxysilane, and monoalkoxysilane. Among these, tetraalkoxysilane is preferred from the viewpoint of facilitating the progress of hydrolysis reaction and polycondensation reaction. Examples of the tetraalkoxysilane include tetramethoxysilane and tetraethoxysilane.

[0034] The aluminum compound having a hydroxy group and / or a hydrolyzable functional group is preferably aluminum hydroxide, aluminum alkoxide, or the like.

[0035] The tin compound having a hydroxy group and / or a hydrolyzable functional group is preferably tin hydroxide, tin alkoxide, or the like.

[0036] The cerium compound having a hydroxy group and / or a hydrolyzable functional group is preferably cerium hydroxide, cerium alkoxide, or the like.

[0037] The titanium compound having a hydroxyl group and / or a hydrolyzable functional group is preferably a titanium alkoxide. Examples of titanium alkoxide include titanium monoalkoxide, titanium dialkoxide, titanium trialkoxide, and titanium tetraalkoxide. Among these, titanium tetraalkoxide is preferred from the viewpoint of facilitating the hydrolysis reaction and polycondensation reaction. Examples of titanium tetraalkoxide include titanium tetraisopropoxide.

[0038] The zirconium compound having a hydroxyl group and / or a hydrolyzable functional group is preferably a zirconium alkoxide. Examples of the zirconium alkoxide include zirconium monoalkoxide, zirconium dialkoxide, zirconium trialkoxide, and zirconium tetraalkoxide. Among these, zirconium tetraalkoxide is preferred from the viewpoint of facilitating the hydrolysis reaction and polycondensation reaction. Examples of the zirconium tetraalkoxide include zirconium tetraisopropoxide.

[0039] The ceramic precursor may be a metal salt (e.g., aluminum salt, tin salt, cerium salt, etc.) that is converted to a hydroxide by hydrolysis. Examples of aluminum salts include aluminum nitrate, aluminum sulfate, aluminum chloride, etc. Examples of tin salts include tin nitrate, tin sulfate, tin chloride, etc. Examples of cerium salts include cerium nitrate, cerium sulfate, cerium chloride, etc. Among these, aluminum chloride, tin chloride, and cerium chloride are preferred from the viewpoint of facilitating the hydrolysis reaction and polycondensation reaction.

[0040] The catalyst functions as a catalyst for the hydrolysis reaction. Examples of the catalyst include an acid and a base. Examples of the acid 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 the base include sodium hydroxide, potassium hydroxide, aqueous ammonia, sodium carbonate, sodium hydrogen carbonate, amines such as trimethylammonium, ammonium hydroxides such as tert-butylammonium hydroxide, and alkali metal alkoxides such as sodium methoxide.

[0041] The macropore-forming agent contributes to the formation of macropores in the porous substrate. Examples of the macropore-forming agent include water-soluble polymers, surfactants, etc. Among these, water-soluble polymers are preferred. The water-soluble polymer induces a sol-gel transition accompanied by a phase separation process (typically spinodal decomposition), which contributes to the formation of a bicontinuous structure of the framework phase and the solvent phase in the gel, and thus to the formation of macropores in the porous substrate.

[0042] Examples of the water-soluble polymer include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyacrylic acid, polyethylene glycol-polypropylene glycol block copolymers, polyvinylpyrrolidone, polystyrene sulfonate sodium salt, and polyallylamine hydrochloride.

[0043] From the viewpoint of efficiently carrying out the phase separation process (typically spinodal decomposition), the weight average molecular weight of the water-soluble polymer is preferably from 8000 to 15000. The weight average molecular weight is measured by GPC (gel permeation chromatography).

[0044] Examples of the surfactant include cationic surfactants such as cetyltrimethylammonium chloride, anionic surfactants such as sodium dodecyl sulfate, and nonionic surfactants such as polyoxyethylene alkyl ether.

[0045] When the ceramic precursor is a semimetallic compound, the reaction solution may contain a mesopore-forming agent. The mesopore-forming agent contributes to the formation of mesopores in the porous substrate. Examples of the mesopore-forming agent include nitrogen compounds. Examples of the nitrogen compounds that can be used as mesopore-forming agents include amide compounds such as urea, formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, and N,N-dimethylacetamide; and heterocyclic compounds such as hexamethylenetetramine. Among these, urea is preferred from the viewpoint of efficient mesopore formation.

[0046] The reaction solution may contain one or more solvents, such as water, an organic solvent, or a mixture of water and an organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, propanol, butanol, etc.; and ketones such as acetone, methyl ethyl ketone, etc. When the solvent is a mixed solvent of water and an organic solvent, the content of the organic solvent is preferably 65 mass % or less based on the mass of the mixed solvent.

[0047] From the viewpoint of appropriately controlling the start time of the reaction, it is preferable to prepare the reaction solution by adding the ceramic precursor to a mixture containing the catalyst, the macropore-forming agent, and, if necessary, the mesopore-forming agent. The reaction is started by adding the ceramic precursor to a mixture containing the catalyst, the macropore-forming agent, and, if necessary, the mesopore-forming agent.

[0048] The reaction solution may be cooled when the reaction solution is stirred. The reaction solution is cooled, for example, so that the temperature of the reaction solution is a temperature at which the sol-gel transition accompanied by a phase separation process (typically spinodal decomposition) is likely to proceed, preferably 60°C or less. The lower limit of the temperature is such that the reaction solution does not freeze, for example, about 1°C.

[0049] For example, when tetramethoxysilane, which is a semimetallic compound having a hydrolyzable functional group, is used as the ceramic precursor, it is preferable to carry out the cooling described above.

[0050] The reaction solution turns into a sol as the hydrolysis reaction and the polycondensation reaction proceed.

[0051] In the hydrolysis reaction, the hydrolyzable functional groups of the ceramic precursor are hydrolyzed to form hydroxyl groups. In the polycondensation reaction, metalloxane oligomers are formed by a dehydration condensation reaction between hydroxyl groups and a dealcoholization condensation reaction between a hydroxyl group and an unhydrolyzed hydrolyzable functional group. For example, when the ceramic precursor is a silicon compound having a hydrolyzable functional group, a siloxane oligomer is formed by a dehydration condensation reaction shown in the following formula (1) and a dealcoholization condensation reaction shown in the following formula (2). In the following formula (2), -OR represents an unhydrolyzed hydrolyzable functional group. ≡Si-OH + HO-Si≡ → ​​≡Si-O-Si≡ + H2O (1) ≡Si-OR + HO-Si≡ → ​​≡Si-O-Si≡ + ROH (2)

[0052] As the hydrolysis and polycondensation reactions proceed further, primary particles of metalloxane oligomers of nanometer size are formed, and secondary particles are formed by aggregation of the primary particles, which causes the reaction solution to become a sol.

[0053] In the gel production process, the sol obtained in the sol production process is heated to a gelation temperature after adding a molding mold as necessary to produce a polymetalloxane gel. In the gel production process, the hydrolysis reaction and polycondensation reaction 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). The produced polymetalloxane gel has a co-continuous structure of a skeletal phase and a solvent phase. The skeletal phase is rich in the metalloxane polymer produced by the hydrolysis reaction and polycondensation reaction, and the solvent phase is rich in the solvent. The skeletal phase and the solvent phase each have a continuous three-dimensional network structure and are entangled with each other, thereby forming a co-continuous structure of the skeletal phase and the solvent phase.

[0054] The molding mold is a mold for molding the gel into a desired shape, and examples of materials for the molding mold include synthetic resins such as polystyrene, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate (PC), silicone, and polytetrafluoroethylene (PTFE), as well as metals such as aluminum and stainless steel.

[0055] From the viewpoint of appropriately forming a co-continuous structure of the skeletal phase and the solvent phase in the gel, the gelation temperature is preferably from 20° C. to 80° C., more preferably from 25° C. to 40° C. The heating time for gelation is preferably from 4 hours to 24 hours.

[0056] <Process (b)> In step (b), pores are formed in the skeleton of the polymetalloxane gel produced in step (a).

[0057] The formation of pores in the skeleton of the polymetalloxane gel can be carried out by a conventional method. When forming pores in the skeleton of the polymetalloxane gel, the polymetalloxane gel produced in step (a) may be reacted with a mesopore-forming agent, if necessary.

[0058] The mesopore-forming agent may be contained in the polymetalloxane gel produced in step (a), in the reaction solution containing the polymetalloxane gel and the mesopore-forming agent, or in both of them. In step (b), pores (pores that will become mesopores in the porous substrate) are formed in the gel skeleton. The reaction solution may contain one or more solvents. The solvent may be contained in the same manner as above.

[0059] When the polymetalloxane gel and the mesopore-forming agent are reacted, they may be reacted under heating under reflux.

[0060] The heating temperature in the heating under reflux is preferably 50° C. or more and 120° C. or less. The heating time in the heating under reflux is preferably 1 hour or more and 36 hours or less, more preferably 4 hours or more and 24 hours or less.

[0061] When a semimetallic compound having a hydrolyzable functional group is used as the ceramic precursor, it is preferable to react the polymetalloxane gel with the mesopore-forming agent under heating under reflux.

[0062] <Process (c)> In step (c), the polymetalloxane gel subjected to step (b) is washed and / or dried as necessary, and then calcined to produce a porous substrate.

[0063] Examples of the cleaning liquid used for cleaning include water, an organic solvent, a mixed solvent of water and an organic solvent, and an aqueous solution containing an acid or a base. The organic solvent may include, for example, alcohols such as methyl alcohol, ethyl alcohol, N-propanol, 2-propanol (IPA), and butanol. Examples of the acid include hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, acetic acid, formic acid, carbonic acid, citric acid, and phosphoric acid. Examples of the base include sodium hydroxide, potassium hydroxide, ammonia, water-soluble amines, sodium carbonate, and sodium hydrogen carbonate.

[0064] Examples of the drying method include natural drying, heat drying, drying using a low surface tension solvent, drying by freeze sublimation, and supercritical drying.

[0065] The firing temperature in the firing is preferably 500° C. or more and 1000° C. or less, more preferably 600° C. or more and 800° C. or less, and the firing time is preferably 1 hour or more and 8 hours or less, more preferably 3 hours or more and 5 hours or less. The firing is usually carried out in an air atmosphere.

[0066] The porous substrate thus obtained has a bicontinuous structure of a ceramic skeleton with mesopores and macropores. The ceramic skeleton of the porous substrate is formed from the skeleton phase of the polymetalloxane gel, and the macropores of the porous substrate are formed from the solvent phase of the polymetalloxane gel.

[0067] The produced porous substrate may be molded into, for example, a columnar body for use, or a molded porous substrate may be produced using a mold or the like and used as is or after molding as necessary, for example, as a columnar body. Specifically, a molded porous substrate can be produced by using a molding mold for molding the gel into a desired shape in the gel production process.

[0068] The amino compounds supported on the porous substrate thus obtained are those having a primary amino group (-NH2), a secondary amino group (-NHR 1 ), tertiary amino group (―NR 1 R 2 ), quaternary ammonium group (-N + R 1 R 2 R 3 ) can be used without particular limitation.1 , R 2 , R 3 are each independently, for example, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, etc. The alkyl group is, for example, an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear or branched. The aryl group is, for example, a monocyclic, bicyclic or tricyclic aromatic hydrocarbon ring group having 6 to 14 carbon atoms. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the substituent that the alkyl group or the aryl group may have include a hydroxyl group and a halogen atom. The halogen atom is selected from a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The amino compound may be, for example, a monoamine type amino compound having one amino group in one molecule of the amino compound, or a polyamine type amino compound having two or more amino groups in one molecule of the amino compound.

[0069] The amino compound may be, for example, a low molecular weight compound or a polymeric compound. As the low molecular weight compound, for example, aliphatic amines and aromatic amines can be used. As the aliphatic amine, chain aliphatic amines and cyclic aliphatic amines can be used, such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, bis(2-hydroxypropyl)amine, N,N'-bis(2-hydroxyethyl)ethylenediamine, monoethanolamine, diethanolamine, diisopropanolamine, methylamine, dimethylamine, diethylamine, methyldiethanolamine, methylethanolamine, piperidine, piperazine, and 2-aminoethylpiperazine. Examples of the aromatic amine include 2-picolylamine, aniline, and m-xylylenediamine. Examples of the polymeric compound include linear polyethyleneimine and branched polyethyleneimine. These amino compounds may be used alone or in combination of two or more. Among these amino compounds, polyamines, primary amines, secondary amines, tertiary amines, quaternary ammonium, aromatic amines, and polyamines are preferred from the viewpoints of ease of being supported on the porous substrate and high acid gas adsorption ability when the amino compound-supported porous substrate of the present invention is used as, for example, an acid gas adsorbent. ethylene It is preferred to use an imine.

[0070] The amino compound used in the present invention may be used in combination with an antioxidant in order to increase the fluidity of the compound and facilitate its support inside the pores. Examples of the antioxidant include ascorbic acid, hydroquinone, 3,5-dibutyl-4-hydroxytoluene, butylhydroxyanisole, α-tocopherol, and polyethylene glycol. These additives may be added alone or in combination of two or more.

[0071] The term "supporting" in the amino compound-supported porous substrate of the present invention includes a case where the amino compound is chemically bonded to the carrier (hereinafter also referred to as "chemically bonded modification") and a case where the amino compound is physically adsorbed to the carrier (hereinafter also referred to as "non-chemically bonded modification"), and may be either one of the supported states or both of the supported states. There is no particular limitation on the method of modifying the porous substrate used in the present invention with amino compound.For example, the method of reacting the functional group (e.g., hydroxyl group) on the surface of the porous substrate with the silane coupling agent having the functional group containing nitrogen element (e.g., primary amino group, secondary amino group, tertiary amino group, quaternary ammonium group) is included, and the silane coupling agent having the functional group containing nitrogen element is chemically fixed on the surface of the porous substrate.

[0072] There is no particular limitation on the method of modifying the porous substrate used in the present invention with an amino compound by non-chemical bonding.For example, an amino compound is mixed with a solvent compatible with the amino compound to prepare a solution, and the solution is mixed with a porous substrate to allow the solution to penetrate into the pores of the porous substrate.Then, the solvent of the solution containing the porous substrate is distilled under reduced pressure, and the solution is dried by heating, so that the amino compound remains in the pores of the porous substrate. Another non-chemically bonded modification method is to place the amino compound and the porous substrate in an autoclave with the two spaced apart from each other, and then evacuate the autoclave and fill it with vapor of the amino compound, thereby introducing the amino compound into the pores of the porous substrate.

[0073] In this way, the amino compound-supported porous substrate of the present invention obtained by supporting the amino compound on the porous substrate has a large amount of amino groups that contribute to gas adsorption due to the macropores of the porous substrate. The amount of amino compound that contributes to gas adsorption (hereinafter also referred to as "amine efficiency") can be calculated by dividing the CO2 adsorption amount per unit mass of the amino compound-supported porous substrate by the amount of amino compound supported per unit mass of the amino compound-supported porous substrate. The specific measurement methods for each will be described in the examples below. The amount of amino groups per unit volume of the amino compound-supported porous substrate of the present invention is preferably 1.0 mmol / mL or more and 30.0 mmol / mL or less, more preferably 2.0 mmol / mL or more and 25.0 mmol / mL or less, and even more preferably 3.0 mmol / mL or more and 20.0 mmol / mL or less.

[0074] The amino compound-supported porous substrate of the present invention is used for adsorption of various gases by utilizing the properties of the amino compound supported thereon. In particular, the adsorbent comprising 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 by utilizing chemical adsorption by amino groups. In particular, the amino compound-supported porous substrate of the present invention has the advantage that the ratio of the amount of amino groups contributing to gas adsorption capacity to the amount of amino compounds supported is high due to the macropores of the porous substrate, and therefore the amino compound-supported porous substrate has the advantage that the gas to be treated and the pressure conditions during use can be selected from a wide range. In particular, when the amino compound-supported porous substrate of the present invention is a molded body, the pressure loss during gas flow is significantly suppressed due to the synergistic effect of its shape and the macropores of the porous substrate, so that it is possible to treat a large amount of the gas to be treated that contains a low concentration of the gas to be adsorbed.For example, it is possible to use the atmosphere as the gas to be treated, and to treat a large amount of carbon dioxide in the atmosphere at high speed.This is extremely advantageous from the viewpoint of preventing global warming by removing carbon dioxide from the atmosphere, and clearing emission regulations by removing carbon dioxide from the gas discharged from the business site.

[0075] The 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 is used, for example, as a raw material for synthesizing various organic compounds, such as methane, propylene, and gasoline. Alternatively, the amino compound-supported porous substrate with adsorbed carbon dioxide can be stored for a long period of time in a storage facility. The desorbed nitrogen oxides are used, for example, as a raw material for synthesizing nitric acid. The desorbed sulfur oxides are used, for example, as a raw material for synthesizing hydrogen sulfide and sulfuric acid.

[0076] Although the present invention has been described based on the preferred embodiment, the present invention is not limited to the above embodiment.

[0077] In relation to the above-mentioned embodiment, the present invention further discloses the following amino compound-supporting porous substrate and acidic gas adsorbent. [1] A porous substrate having at least macropores; an amino compound supported in at least some of the pores of the porous substrate; An amino compound-supported porous substrate comprising: The porous substrate has a total pore volume measured by mercury intrusion porosimetry of 0.55 mL / mL or more and 0.95 mL / mL or less per unit volume of the porous substrate. [2] The porous substrate supporting an amino compound according to [1], wherein the most frequent pore size of the macropores measured by mercury intrusion porosimetry in a pore size range of 50 nm to 500 μm is 0.05 μm to 3.0 μm. [3] The amino compound-supporting porous substrate according to [1] or [2], wherein the skeleton of the porous substrate contains an element selected from silicon, aluminum, tin, cerium, titanium and zirconium. [4] The amino compound-supported porous substrate according to any one of [1] to [3], wherein the amount of amino groups contained in the amino compound-supported porous substrate is 1.0 mmol / mL or more and 30.0 mmol / mL or less per unit volume of the amino compound-supported porous substrate. [5] The amino compound is a polyamine, a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium, an aromatic amine, or a polyamine. ethylene The amino compound-supported porous substrate according to any one of [1] to [4], wherein the amino compound is at least one selected from the group consisting of imines. [6] The amino compound-supported porous substrate according to any one of [1] to [5], wherein the total pore volume of the amino compound-supported porous substrate measured by mercury intrusion porosimetry is 0.05 mL / mL or more and 0.80 mL / mL or less per unit volume of the amino compound-supported porous substrate. [7] The porous substrate further has mesopores, The amino compound-supporting porous substrate according to any one of [1] to [6], wherein the porous substrate has a co-continuous structure of a skeleton in which the mesopores are formed and the macropores. [8] The amino compound-supporting porous substrate according to [7], wherein the ratio of the most frequent pore size of the macropores to the most frequent pore size of the mesopores is 5 or more and 200 or less. [9] The amino compound-supporting porous substrate according to any one of [1] to [8], wherein the porous substrate is a molded body.

[10] The amino compound-supporting porous substrate according to [9], wherein the molded body is a columnar body having an average diameter of 1.5 mm or more and 20 mm or less.

[11] The amino compound-supported porous substrate according to [9] or

[10] , wherein the amino compound-supported porous substrate has a compressive strength of 5 N or more.

[12] An acidic gas adsorbent comprising the amino compound-supported porous substrate according to any one of [1] to

[11] . EXAMPLES

[0078] 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 such examples. Unless otherwise specified, "%" means "% by mass".

[0079] Example 1 (1) Manufacturing of porous substrate The porous substrate of this example was prepared by the manufacturing method described in Japanese Patent No. 6924338. 2052 g of polyethylene glycol 10000, 2160 g of urea, 14.5 g of acetic acid, and 24 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. A sol preparation system consisting of two liquid delivery pumps, a static mixer, and a cooling piping section (2 ° C.) was fed with an aqueous polyethylene glycol solution at a liquid delivery rate of 90 mL per minute and tetramethoxysilane at a liquid delivery rate of 45 mL per minute, and mixed and cooled in the system to obtain a mixed solution. The mixed solution was collected in a stirring tank cooled to 15 ° C. and stirred for 30 minutes. After stirring, the sol solution was fed to a 600 mL container, a mold for forming a cylindrical pellet with a diameter of 4.6 mm was added, and the mixture was heated in a warm bath at 30 ° C. to prepare a polysiloxane gel.

[0080] The resulting polysiloxane gel was then added to a reaction vessel containing 100 mL of 3 mol / L urea water and heated under reflux for 12 hours. After the reaction was completed, the resulting polysiloxane gel was washed with water and dried for 12 hours in a dryer set at 60°C. After drying, the gel was baked at 600°C for 5 hours in an air atmosphere to obtain a cylindrical porous substrate with a diameter of 4.6 mm. The length of the resulting porous substrate was adjusted by cutting it so that the aspect ratio was 1.5.

[0081] The structure of the obtained porous substrate was observed with an SEM (JEOL JSM-7900F), and it was confirmed that the substrate had a bicontinuous structure of a silica framework 3 with mesopores 4 formed therein and macropores 2, as shown in Figure 2.

[0082] (2) Amino compound loading (non-chemically bonded modification) Polyethyleneimine 600 (weight average molecular weight 600) was used as the amino compound. 5 g of polyethyleneimine 600 was dissolved in 30 mL of ethanol, and then 5 g of the porous substrate was added. The mixed solution obtained by leaving it to stand overnight was reduced in pressure at 70°C to remove the ethanol, and the amino compound was supported in the pores of the porous substrate (non-chemically bonded modification), thereby obtaining the desired amino compound-supported porous substrate.

[0083] [Examples 2 to 6] The diameter of the porous substrate was as shown in Table 1 below. The mass ratio of the amino compound to the porous substrate was as shown in the same table. Other than that, an amino compound-supported porous substrate was obtained in the same manner as in Example 1.

[0084] Example 7 In the production of the porous substrate, the same procedure as in Example 1 was carried out except that the heating reflux time was changed to 5 hours to obtain a porous substrate carrying an amino compound.

[0085] Example 8 In the production of the porous substrate, the same procedure as in Example 1 was carried out except that the heating reflux time was changed to 24 hours to obtain a porous substrate carrying an amino compound.

[0086] Example 9 An amino compound-supporting porous substrate was obtained in the same manner as in Example 1, except that in the production of the porous substrate, the amount of polyethylene glycol added was changed to 1949 g.

[0087] Example 10 An amino compound-supporting porous substrate was obtained in the same manner as in Example 1, except that in the production of the porous substrate, the amount of polyethylene glycol added was 2155 g.

[0088] Example 11 An amino compound-supporting porous substrate was obtained in the same manner as in Example 1, except that the porous substrate produced in Example 1 was pulverized in a mortar to give a powder having a particle size of 8 μm.

[0089] Comparative Example 1 (1) Manufacturing of porous substrate (mesoporous silica) 424.8 g of hydrochloric acid (36 mass%, Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise to the mixed solution, and the mixture was stirred at 35°C for 24 hours. Then, the mixture was stirred at 95°C for 24 hours. After stirring, the mixed solution was filtered, and the obtained solid was dried at 120°C to remove moisture. After drying, the obtained solid was placed in an electric furnace, heated to 550°C at a heating rate of 10°C / min, and held at that temperature for 6 hours to obtain mesoporous silica.

[0090] Next, 37.5 g of the obtained mesoporous silica, 12.8 g of fumed silica (M5, manufactured by Cabot Corporation), and 29.5 g of water were mixed. At this time, 0.31 g of methylcellulose was added. The obtained mixture was put into an extrusion granulator (Multigran MG-55-2, manufactured by Dalton Co., Ltd.) and granulated at 20 rpm to obtain a cylindrical porous substrate precursor. The obtained porous substrate precursor was dried at 120 ° C. to remove moisture. Thereafter, it was placed in an electric furnace, heated to 500 ° C. at a heating rate of 5 ° C. / min, and held as it is for 2 hours to obtain a cylindrical porous substrate. The length of the obtained porous substrate was adjusted by cutting it so that the aspect ratio was 1.5.

[0091] (2) Amino compound loading (non-chemically bonded modification) The amino compound was supported in the same manner as in Example 1.

[0092] Comparative Example 2 An amino compound-supported porous substrate was obtained in the same manner as in Comparative Example 1, except that the mass ratio of the amino compound to the porous substrate was set as shown in Table 1 below.

[0093] Comparative Example 3 An amino compound-supported porous substrate was obtained in the same manner as in Comparative Example 1, except that the amino compound-supported porous substrate was pulverized in a mortar to a particle size of 8 μm to prepare a powder.

[0094] Comparative Example 4 An amino compound-supported porous substrate was obtained in the same manner as in Comparative Example 3, except that the mass ratio of the amino compound to the porous substrate was set as shown in Table 1 below.

[0095] 〔evaluation〕 For the porous substrates used in the examples and comparative examples, the bulk density, total pore volume Vt, macropore volume Vm, mesopore volume Vs, most frequent pore diameter Dm of macropores, and most frequent pore diameter Ds of mesopores were measured by the following methods. For the amino compound-supporting porous substrates obtained in the Examples and Comparative Examples, the bulk density, macropore volume Vma, mesopore volume Vsa, and total pore volume Va were measured in the same manner. For the amino compound-supporting porous substrates obtained in the Examples and Comparative Examples, the amount of amino groups and the amount of carbon dioxide adsorbed were measured by the following methods, and the amine efficiency was calculated. Furthermore, when the porous substrate was a molded body, the compressive strength was measured by the following method. The results are shown in Table 1 below.

[0096] [Bulk density] The bulk density of the porous substrate and the amino compound-supported porous substrate was measured by mercury intrusion method using a mercury porosimeter (Micromeritics' "Autopore IV9520") under the following measurement conditions and procedures. (Measurement conditions) "Mercury parameters; advancing contact angle: 130.0 degrees, receding 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, equilibration time: 10 secs", "High pressure parameters; equilibration time: 10 secs", "Injection volume: adjusted to be between 25% and 90%", "Measurement environment: 20°C". (Measurement Procedure) (1) Weigh out approximately 0.5 g of sample and place it in the sample cell, then enter the weighed value. (2) The range of 0.0048 to 0.2068 MPa was measured in the low pressure section. (3) The range of 0.2068 to 255.1060 MPa was measured in the high pressure section. (4) The pore size distribution was calculated from the mercury injection pressure and the amount of mercury injected. (2), (3), and (4) were performed automatically using the software that came with the device. From the pore size distribution calculated as above, the bulk density was calculated using the software. The bulk density was calculated by referring to "Bulk Density at 0.0035MPa" on the software.

[0097] [Pore volume Vt, Vm, Vs, Va, Vma, Vsa, Va] The pore volume was measured by mercury intrusion using a mercury porosimeter (Micromeritics' "Autopore IV9520"). In the mercury intrusion method, pressure was applied to the pores of the porous substrate and the amino compound-supported porous substrate to inject mercury, and the pore volume per unit mass was calculated from the pressure and the amount of mercury injected. The pore volume per unit mass was multiplied by the bulk density measured by the above-mentioned method to calculate the pore volume per unit volume. In this specification, the pore volumes Vm and Vma of the macropores were analyzed by mercury intrusion porosimetry in the range of pores having diameters of 50 nm to 500 μm, and the pore volumes Vs and Vsa of the mesopores were analyzed by mercury intrusion porosimetry in the range of pores having diameters of more than 2 nm to less than 50 nm. The total pore volumes Vt and Va were the sum of the pore volumes of the macropores and mesopores.

[0098] [Most frequent pore size of macropores Dm] The most frequent pore size Dm of the macropores was measured by mercury intrusion using a mercury porosimeter (Micromeritics' "Autopore IV9520"). In the mercury intrusion method, pressure was applied to the pores of the porous substrate to inject mercury, and the pore volume and specific surface area were obtained from the pressure and the amount of mercury injected, and the pore size was calculated from the relationship between the pore volume and the specific surface area when the pores were assumed to be cylindrical. In this specification, the mercury intrusion method was used to analyze the pores having a diameter of 50 nm to 500 μm.

[0099] [Most frequent mesopore size Ds] Similar to the most frequent pore size of macropores, the most frequent pore size Ds of mesopores was measured by mercury intrusion porosimeter (Micromeritics "Autopore IV9520"). In this specification, the mesopores were analyzed in the range of diameters from more than 2 nm to less than 50 nm by mercury intrusion porosimeter.

[0100] [Compressive strength] The side of the porous substrate in a dry state was pressed using a digital hardness tester KHT-40N (pressure diameter 3 mm) manufactured by Fujiwara Seisakusho, and the pressure (N) at which it broke was measured. In this specification, the compressive strength test was performed using five porous substrates, and the arithmetic average value of the five measured values ​​was taken as the compressive strength value.

[0101] [Amino group amount] The amount of amino groups contained in the amino compound-supported porous substrate per unit mass was quantified using an oxygen, nitrogen, and hydrogen analyzer ONH836 manufactured by LECO Japan LLC. The amount of amino groups thus obtained was multiplied by the bulk density of the porous substrate (after the amino compound was supported) to calculate the amount of amino groups per unit volume of the porous substrate.

[0102] [Amount of carbon dioxide adsorbed] The amount of carbon dioxide adsorption was measured using BELCATII manufactured by Microtrack Bell. 0.1 g of the amino compound-supported porous substrate was placed in the 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 50°C, and a gas with a carbon dioxide concentration of 4 vol% was passed through at 50 sccm for 25 minutes. Then, the flow of carbon dioxide was stopped, helium was passed 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 adsorption was calculated from the peak area detected by TCD.

[0103] [Amine efficiency] The amount of carbon dioxide adsorption measured by the above-mentioned method was divided by the amount of amino groups contained in the amino compound-supporting porous substrate per unit mass to calculate the amine efficiency.

[0104] [Table 1]

[0105] As is clear from the results shown in Table 1, the amino compound-supported porous substrate obtained in each Example had a high carbon dioxide adsorption amount and a higher amine efficiency than the comparative examples.

[0106] [Examples 12 to 20] An amino compound-supported porous substrate was obtained in the same manner as in Example 1, except that the pellet diameter of the porous substrate, the type of amino compound supported, and the mass ratio of the amino compound to the porous substrate were as shown in the following Table 2. In Example 18, polyethyleneimine 600 (PEI600) and triethylenetetramine (TETA) were mixed in the mass ratio shown in the same table and used.

[0107] Example 21 An amino compound-supporting porous substrate was obtained in the same manner as in Example 1, except that 1.25 g of polyethylene glycol was added to 5 g of polyethyleneimine 600.

[0108] [Examples 22 and 23] An amino compound-supported porous substrate was obtained in the same manner as in Example 21, except that the amount of polyethylene glycol added was changed to the amount shown in Table 2 below.

[0109] Example 24 (1) Manufacturing of porous substrate 10.0 g of the porous substrate obtained by the procedure of Example 1 was added to a reaction vessel, 40 mL of 0.1% aqueous acetic acid solution, 30 mL of ethanol, and 9.84 g of 3-glycidyloxypropyltrimethoxysilane were added, and the mixture was heated to reflux at 100° C. for 4 hours. The porous substrate was then separated from the solution by filtration, washed with approximately 500 mL of water, and dried to obtain an epoxy-supported porous substrate.

[0110] (2) Supporting amino compounds The obtained epoxy-supported porous substrate was then added to a reaction vessel, and 70 mL of water and 6.66 g of polyethyleneimine (weight average molecular weight 600) were added, followed by heating at 80°C for 4 hours. After heating, the porous substrate was separated from the solution by filtration, washed with approximately 500 mL of water, and dried to obtain an amino compound-supported porous substrate (chemically bonded modification). Note that the mass ratio of the amino compound to the porous substrate in Table 2 is indicated as "-" because it is difficult to define it in the same way as in other examples.

[0111] Example 25 (1) Manufacturing of porous substrate A porous substrate was prepared in the same manner as in Example 1, except that in the polysiloxane gel preparation step, 171 g of polyethylene glycol 10,000, 180 g of urea, 1.2 g of acetic acid, and 1,650 g of water were used, and in the porous substrate preparation step, heating was performed at 90°C for 24 hours under reflux, and the drying time was 20 hours.

[0112] (2) Supporting amino compounds Next, 1 kg of the obtained porous substrate was added to a reaction vessel containing 5 L of ion-exchanged water and 1.17 g of 3-aminopropyltrimethoxysilane, and heated under reflux at 90° C. for 5 hours. The porous substrate was separated from the aqueous solution by filtration, washed three times with ion-exchanged water, and dried at 80° C. for 20 hours to obtain an amino compound-supported porous substrate (chemically bonded modification). Furthermore, the obtained amino compound-supported porous substrate was impregnated with a solution containing polyethyleneimine 600 in the same manner as in Example 1 to support polyethyleneimine 600, thereby obtaining an amino compound-supported porous substrate (chemically bonded modification+non-chemically bonded modification). Note that the mass ratio of the amino compound to the porous substrate in Table 2 is indicated as "-" because it is difficult to define it in the same manner as in other Examples.

[0113] [Table 2]

[0114] From Table 2, it can be seen that the porous substrate of the present invention can support various amino compounds, and that the obtained amino compound-supported porous substrate has a high carbon dioxide adsorption capacity and high amine efficiency, regardless of the type of amino compound or the supporting method. [Industrial Applicability]

[0115] According to the present invention, there is provided an amino compound-supported porous substrate having a large pore volume, capable of supporting various amino compounds, and in which the proportion of amino compounds that contribute to the adsorption performance relative to the supported amount is higher than that of conventional adsorbents supporting the same amino compounds, and an acidic gas adsorbent using the same.

Claims

1. A porous substrate having at least macropores and mesopores; a polymeric amino compound supported in the macropores and the mesopores; An amino compound-supported porous substrate comprising: The porous substrate has a total pore volume measured by mercury intrusion porosimetry of 0.55 mL / mL or more and 0.95 mL / mL or less per unit volume of the porous substrate; The porous substrate has a mode pore size of the macropores of 0.05 μm or more and 3.0 μm or less, measured by mercury intrusion porosimetry in a pore size range of 50 nm or more and 500 μm or less; The porous substrate has a pore volume of the macropores measured by mercury intrusion in a pore diameter range of 50 nm to 500 μm per unit volume of the porous substrate, of 0.20 mL / mL to 0.70 mL / mL, The porous substrate has a pore volume of the mesopores measured by mercury intrusion porosimetry in a pore diameter range of more than 2.0 nm and less than 50 nm, which is 0.05 mL / mL or more and 0.50 mL / mL or less per unit volume of the porous substrate; The amount of amino groups contained in the amino compound-supported porous substrate is 1.0 mmol / mL or more and 30.0 mmol / mL or less per unit volume of the amino compound-supported porous substrate.

2. The porous substrate is an amino compound-supported porous substrate as described in claim 1, wherein the most frequent pore diameter of the mesopores measured by mercury intrusion porosimetry in the pore diameter range of more than 2.0 nm and less than 50 nm is 5.0 nm or more and 30 nm or less.

3. 3. The amino compound-supporting porous substrate according to claim 1, wherein the skeleton of the porous substrate contains an element selected from the group consisting of silicon, aluminum, tin, cerium, titanium and zirconium.

4. The amino compound-supported porous substrate according to claim 1 or 2, wherein the polymeric amino compound is polyethyleneimine.

5. The amino compound-supported porous substrate according to claim 1 or 2, wherein the total pore volume of the amino compound-supported porous substrate measured by mercury intrusion porosimetry is 0.05 mL / mL or more and 0.80 mL / mL or less per unit volume of the amino compound-supported porous substrate.

6. The amino compound-supported porous substrate described in claim 1 or 2, wherein the porous substrate has a co-continuous structure between a skeleton in which the mesopores are formed and the macropores.

7. 7. The amino compound-supporting porous substrate according to claim 6, wherein the ratio of the most frequent pore size of the macropores to the most frequent pore size of the mesopores is 5 or more and 200 or less.

8. The amino compound-supporting porous substrate according to claim 1 or 2, wherein the porous substrate is a molded body.

9. 9. The amino compound-supporting porous substrate according to claim 8, wherein the molded body is a columnar body having an average diameter of 1.5 mm or more and 20 mm or less.

10. The amino compound-supported porous substrate according to claim 8, wherein the amino compound-supported porous substrate has a compressive strength of 5 N or more.

11. 3. An acidic gas adsorbent comprising the amino compound-supported porous substrate according to claim 1 or 2.

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