Carbon dioxide absorbent, carbon dioxide separation method, carbon dioxide separation and capture method, and device using carbon dioxide absorbent

Abstract

To provide a carbon dioxide absorbent having excellent carbon dioxide absorption performance.SOLUTION: A compound for a carbon dioxide absorbent is a phosphine oxide compound represented by the general formula (1) in the figure (where a, b and c each represent an integer from 1 to 10 inclusive, and R1, R2 and R3 each independently represent an amino group or a hydroxy group, with at least one of R1, R2 and R3 being an amino group).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a compound for a carbon dioxide absorbent, a carbon dioxide absorbent, a carbon dioxide separation method, a carbon dioxide separation and capture method, and an apparatus using the carbon dioxide absorbent. [Background technology]

[0002] In recent years, the concentration of greenhouse gases such as carbon dioxide and methane in the atmosphere has continued to increase due to increased consumption of fossil fuels such as oil and coal in industrial activities, as well as deforestation, and global warming, which is causing temperatures to rise on a global scale, is progressing.If global warming continues at this rate, it is thought that serious impacts will appear in various areas, such as desertification of the earth's surface, rising sea levels, and changes in ecosystems.

[0003] Under these circumstances, in order to prevent global warming, attention is being paid to technologies that capture carbon dioxide as well as curbing carbon dioxide emissions with the aim of reducing greenhouse gases. Carbon dioxide capture technologies include chemical absorption, physical absorption, solid absorption, and membrane separation, but chemical absorption is the most widely used method as it can handle a wide range of concentrations. In this chemical absorption method, carbon dioxide is absorbed into a liquid through a chemical reaction, and the absorbent liquid is heated to release and capture the carbon dioxide.

[0004] As a liquid used for absorbing carbon dioxide, for example, Patent Document 1 discloses an ionic liquid having an aminium cation having one or more primary or secondary amino groups and an ethylenediamine or propylenediamine skeleton. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-10760 Summary of the Invention [Problem to be solved by the invention]

[0006] Although the carbon dioxide absorbent described in Patent Document 1 can absorb a large amount of carbon dioxide at room temperature, there is room for further improvement in the carbon dioxide absorption performance.

[0007] Therefore, an object of the present invention is to provide a compound for a carbon dioxide absorbent and a carbon dioxide absorbent that have excellent carbon dioxide absorption performance, and further a carbon dioxide absorbent that, in addition to the above-mentioned carbon dioxide absorption performance, can easily desorb carbon dioxide when the absorbent is regenerated, a carbon dioxide separation method and a carbon dioxide separation and recovery method that use the carbon dioxide absorbent, and an apparatus that uses the carbon dioxide absorbent. [Means for solving the problem]

[0008] In view of the above-mentioned circumstances, the present inventors have conducted extensive research and have found that a phosphine oxide compound represented by the following general formula (1) has better carbon dioxide absorption performance than conventional compounds, and furthermore, can easily desorb carbon dioxide when the carbon dioxide absorbent is regenerated, and have thus completed the present invention.

[0009] [ka]

[0010] (In the formula, a, b, and c represent integers of 1 or more and 10 or less, and R 1 , R 2 and R 3 each independently represents an amino group or a hydroxy group, R 1 , R 2 and R 3 At least one of the groups is an amino group.

[0011] That is, the present invention (1) relates to a compound represented by the following general formula (1):

[0012] [ka]

[0013] (In the formula, a, b, and c represent integers of 1 or more and 10 or less, and R 1 , R 2 and R 3 each independently represents an amino group or a hydroxy group, R 1 , R 2 and R 3 At least one of the groups is an amino group. The present invention provides a compound for use as a carbon dioxide absorbent, which is a phosphine oxide compound represented by the following formula:

[0014] The present invention (2) also provides a carbon dioxide absorbent characterized by containing the compound for a carbon dioxide absorbent of the present invention (1).

[0015] The present invention (3) also provides a carbon dioxide separation method, comprising a carbon dioxide separation step of contacting a mixed gas containing carbon dioxide with the carbon dioxide absorbent of the present invention (2) to cause the carbon dioxide absorbent to absorb the carbon dioxide in the mixed gas, thereby separating carbon dioxide from the mixed gas.

[0016] The present invention (4) also provides a method for separating and capturing carbon dioxide, comprising: a carbon dioxide separation step of bringing a mixed gas containing carbon dioxide into contact with the carbon dioxide absorbent of the present invention (2) to cause the carbon dioxide absorbent to absorb the carbon dioxide in the mixed gas, thereby separating carbon dioxide from the mixed gas; and a carbon dioxide recovery step of heating the carbon dioxide absorbent that has absorbed carbon dioxide in the carbon dioxide separation step at a temperature of 50°C or higher and 150°C or lower to desorb carbon dioxide from the carbon dioxide absorbent that has absorbed the carbon dioxide, thereby regenerating the carbon dioxide absorbent and recovering the desorbed carbon dioxide.

[0017] The present invention (5) also provides an apparatus characterized by using the carbon dioxide absorbent of the present invention (3). [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a compound for a carbon dioxide absorbent and a carbon dioxide absorbent that have excellent carbon dioxide absorption performance, a carbon dioxide absorbent that can easily desorb carbon dioxide when the absorbent is regenerated in addition to the above-mentioned carbon dioxide absorption performance, a carbon dioxide separation method that uses the carbon dioxide absorbent of the present invention, a carbon dioxide separation and recovery method, and an apparatus that uses the carbon dioxide absorbent of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described below based on preferred embodiments. The compound for a carbon dioxide absorbent of the present invention has the following general formula (1):

[0020] [ka]

[0021] (In the formula, a, b, and c represent integers of 1 or more and 10 or less, and R 1 , R 2 and R 3 each independently represents an amino group or a hydroxy group, R 1 , R 2 and R 3 At least one of the groups is an amino group. It is a phosphine oxide compound represented by the formula:

[0022] The phosphine oxide compound represented by general formula (1) has a phosphine oxide structure (αP=O), and therefore has high heat resistance, a low vapor pressure within a heating temperature range during regeneration of the carbon dioxide absorbent after carbon dioxide absorption, for example, a heating temperature range of 50°C or higher and 150°C or lower, and is almost non-volatile.

[0023] In general formula (1), a, b, and c represent integers of 1 or more and 10 or less, preferably 1 or more and 4 or less, and more preferably 3 or more and 4 or less. The numbers a, b, and c may be the same or different, but are preferably the same from the viewpoint of ease of synthesis. In the present invention, it is particularly preferred that a, b, and c are each 3 from the viewpoint of industrial availability.

[0024] R in general formula (1) 1 , R 2 and R 3 R each independently represents an amino group (-NH2) or a hydroxy group (-OH). 1 , R 2 and R 3 may be the same or different, but are preferably the same from the viewpoint of ease of synthesis. 1 , R 2 and R 3 At least one of the groups is an amino group, and it is preferable that all of the groups are amino groups.

[0025] The compound for a carbon dioxide absorbent of the present invention can absorb carbon dioxide by reacting the amino group of the phosphine oxide compound represented by general formula (1) with carbon dioxide. In other words, the compound for a carbon dioxide absorbent of the present invention is a compound used as a substance for absorbing carbon dioxide in a carbon dioxide absorbent.

[0026] The carbon dioxide absorbent of the present invention is characterized by containing the compound for a carbon dioxide absorbent of the present invention. That is, the carbon dioxide absorbent of the present invention is characterized by containing a phosphine oxide compound represented by general formula (1). In the carbon dioxide absorbent of the present invention, the phosphine oxide represented by general formula (1) absorbs carbon dioxide. The phosphine oxide compound represented by general formula (1) in the carbon dioxide absorbent of the present invention is the same as the phosphine oxide compound represented by general formula (1) in the compound for a carbon dioxide absorbent of the present invention.

[0027] In the carbon dioxide absorbent of the present invention, the form of the phosphine oxide compound represented by general formula (1) is not particularly limited, and may be, for example, supported on a carrier, dissolved in an aqueous solvent, or present as a mixture with a soluble organic solvent or an amine compound.

[0028] The carbon dioxide absorbent of the present invention is characterized by comprising a porous carrier and a compound for a carbon dioxide absorbent of the present invention supported on the porous carrier. That is, the carbon dioxide absorbent of the present invention is characterized by comprising a porous carrier and a phosphine oxide compound represented by general formula (1) supported on the porous carrier. In the carbon dioxide absorbent of the present invention, the phosphine oxide compound represented by general formula (1), which is a liquid, is taken into the pores of the porous carrier and physically adsorbed, so that the phosphine oxide compound represented by general formula (1) is supported on the porous carrier.

[0029] The porous carrier for the carbon dioxide absorbent of the present invention is not particularly limited as long as it has a porous structure having a large number of internal pores, and can incorporate a phosphine oxide compound represented by general formula (1) into the internal pores and physically adsorb and retain the phosphine oxide compound represented by general formula (1) within the pores. Examples of the porous carrier include activated carbon, silica gel, layered silicate, mesoporous silica, zeolite, vermiculite, molecular sieve, porous silica, diatomaceous earth, porous resin, porous fiber, porous metal-organic framework, porous alumina, porous ceramic, porous concrete, activated clay, clay mineral, and composites thereof. In terms of being able to increase the amount of the phosphine oxide compound represented by general formula (1) supported, activated carbon, silica gel, mesoporous silica, zeolite, molecular sieve, a composite of alumina and silica gel, and a composite of alumina and mesoporous silica are preferred. Furthermore, when the porous support is a porous body capable of retaining water within its pores, such as activated carbon, silica gel, mesoporous silica, zeolite, molecular sieve, a composite of alumina and silica gel, or a composite of alumina and mesoporous silica, when the carbon dioxide-containing gas to be treated contains moisture, the moisture in the gas to be treated is adsorbed into the pores of the porous body, making it possible to prevent the carbon dioxide absorbent compound from eluting from the porous support, and thus improving the carbon dioxide absorption performance of the carbon dioxide absorbent. The porous body capable of retaining water within its pores is not particularly limited as long as it can retain water within its pores, but examples include those that can retain water at a moisture content of 5 to 30% by mass, preferably 10 to 25% by mass.

[0030] The BET specific surface area of ​​the porous support is preferably 1.0×10 1 ~5.0×10 3 m 2 / g, preferably 5.0 × 10 1 ~2.0×10 3 m 2 The pore volume of the porous carrier as measured by a gas adsorption method is preferably 0.1 to 2.0 cm3. 3 / g, preferably 0.3 to 1.5 cm3 / g.

[0031] Examples of the shape of the porous carrier include granular, powdery, fibrous, plate-like, cylindrical, honeycomb, dice-like, and rectangular parallelepiped shapes. Among these, granular or powdery shapes are preferred from the viewpoints of contact with a mixed gas containing carbon dioxide and packing into packing equipment such as a column or tower. The porous carrier may also be in the form of a molded body.

[0032] Among the porous supports, from the viewpoints of ease of handling and ability to easily support the liquid phosphine oxide compound represented by general formula (1), activated carbon, silica gel, mesoporous silica, zeolite, molecular sieve, a composite of alumina and silica gel, and a composite of alumina and mesoporous silica are preferred, and activated carbon, silica gel, mesoporous silica, a composite of alumina and silica gel, and a composite of alumina and mesoporous silica are particularly preferred.

[0033] Various types of activated carbon can be used in the present invention, including activated carbon made from raw materials such as wood, coconut shells, coal, petroleum pitch, coke, and coal tar. The activated carbon may be a molded product. In addition to the above-mentioned properties of the porous carrier, the activated carbon preferably has physical properties measured according to JIS K1474 (activated carbon testing method) of 0.1 to 5.0% loss on drying, 0.1 to 5.0% ignition residue, 0.25 to 0.85 g / ml packing density, 14.0 to 41.0% acetone adsorption capacity, 600 to 2600 mg / g iodine adsorption capacity, and 90.0 to 100.0% hardness.

[0034] The silica gel used in the present invention includes various silica gels, and preferably contains silicon oxide in an amount of 99% by mass or more, particularly 99.9% by mass or more. The silica gel may be in the form of a molded body. In addition to the above-mentioned properties of the porous carrier, the silica gel preferably has an average particle size of 0.005 to 10 mm as measured by a scanning electron microscope, and preferably has a loss on drying of 10% or less.

[0035] Various zeolites can be used in the present invention, including, for example, LTA zeolite, FER zeolite, MWW zeolite, MFI zeolite, MOR zeolite, LTL zeolite, FAU zeolite, and BEA zeolite. The zeolite may be in the form of a molded body. In addition to the above-described properties of the porous carrier, the zeolite preferably has an average particle size of 0.01 to 15 mm as measured by a scanning electron microscope.

[0036] In the carbon dioxide absorbent of the present invention, when two or more phosphine oxide compounds represented by the general formula (1) are supported on the porous carrier, the two or more phosphine oxide compounds may be supported in the form of a mixed liquid in which the two or more phosphine oxide compounds represented by the general formula (1) are mixed, or each of the two or more phosphine oxide compounds represented by the general formula (1) may be supported on a different part of the porous carrier. That is, for example, when two phosphine oxide compounds represented by the general formula (1) are supported on the porous carrier, the two phosphine oxide compounds represented by the general formula (1) may be mixed first, and the resulting mixed liquid may be incorporated into the pores of the porous carrier to support the two phosphine oxide compounds represented by the general formula (1). Alternatively, one of the two phosphine oxide compounds represented by the general formula (1) may be incorporated into the pores of the porous carrier first, and then the other phosphine oxide compound represented by the general formula (1) may be incorporated into the pores of the porous carrier to support the two phosphine oxide compounds represented by the general formula (1). The same applies to the case where three or more phosphine oxide compounds represented by general formula (1) are supported on a porous carrier.

[0037] The impregnation rate (content) of the phosphine oxide compound represented by general formula (1) in the carbon dioxide absorbent of the present invention is not particularly limited, but is preferably 5 to 60 mass %, more preferably 5 to 55 mass %, and particularly preferably 10 to 55 mass %, relative to the entire carbon dioxide absorbent. When the impregnation amount of the phosphine oxide compound represented by general formula (1) in the carbon dioxide absorbent is within the above range, the compound is uniformly present on the inner surfaces of the pores of the porous support, thereby enabling efficient absorption of carbon dioxide.

[0038] The carbon dioxide absorbent of the present invention is supported on a porous carrier and is a phosphine oxide compound represented by general formula (1) that is capable of chemically adsorbing carbon dioxide. This enables the carbon dioxide absorbent to more efficiently absorb carbon dioxide when the temperature is −20° C. or higher and 60° C. or lower, and also facilitates desorption of carbon dioxide, making it easy to regenerate the carbon dioxide absorbent.

[0039] The carbon dioxide absorbent of the present invention is present over the surface of a porous carrier having a large surface area, and therefore the contact area between the phosphine oxide compound represented by general formula (1) and carbon dioxide can be increased, thereby increasing the carbon dioxide absorption efficiency of the carbon dioxide absorbent of the present invention.

[0040] The carbon dioxide absorbent of the present invention is in a form supported on a solid carrier, and therefore can be packed into a column or a reaction tower for use. When packed into a column or a reaction tower, the carbon dioxide absorbent of the present invention forms appropriate gaps, compared with a liquid carbon dioxide absorbent, and can therefore come into contact with carbon dioxide or a carbon dioxide-containing gas more efficiently.

[0041] The carbon dioxide absorbent of the present invention can separate and recover carbon dioxide from a mixed gas containing carbon dioxide. The mixed gas is not particularly limited in terms of other components, so long as it contains carbon dioxide. Examples of other components include oxygen, nitrogen, carbon monoxide, nitric oxide, nitrogen dioxide, dinitrogen monoxide, dinitrogen trioxide, dinitrogen tetroxide, dinitrogen pentoxide, sulfur monoxide, sulfur dioxide, sulfur trioxide, phosphoric acid, sulfuric acid, nitric acid, hydrochloric acid, and water. The concentration of carbon dioxide in the mixed gas is not particularly limited, and may be a high concentration with a purity of approximately 100%, or a concentration similar to that present in the atmosphere.

[0042] The carbon dioxide absorbent of the present invention is useful as an absorbent for separating and recovering carbon dioxide from a mixed gas containing carbon dioxide emitted from, for example, power plants such as coal-fired power plants and natural gas-fired power plants, factories such as chemical plants, waste disposal sites and steelworks, transportation equipment such as automobiles, aircraft and ships, etc. It is also useful as an absorbent used in a DAC (Direct Air Capture) device that separates and recovers carbon dioxide directly from the atmosphere. That is, the carbon dioxide absorbent of the present invention is suitable as a carbon dioxide absorbent for use in various devices such as devices used in power plants, factories, and transportation equipment, and DAC devices.

[0043] Next, a carbon dioxide separation method and a carbon dioxide separation and recovery method using the carbon dioxide absorbent of the present invention will be described.

[0044] The carbon dioxide separation method of the present invention is a carbon dioxide separation method characterized by comprising a carbon dioxide separation step (A) of contacting a mixed gas containing carbon dioxide with the carbon dioxide absorbent of the present invention to cause the carbon dioxide absorbent to absorb the carbon dioxide in the mixed gas, thereby separating carbon dioxide from the mixed gas.

[0045] The carbon dioxide separation and capture method of the present invention is a method for separating and capturing carbon dioxide, characterized by comprising: a carbon dioxide separation step (A) of bringing a mixed gas containing carbon dioxide into contact with the carbon dioxide absorbent of the present invention to cause the carbon dioxide absorbent to absorb the carbon dioxide in the mixed gas, thereby separating carbon dioxide from the mixed gas; and a carbon dioxide capture step (B) of heating the carbon dioxide absorbent that has absorbed carbon dioxide in the carbon dioxide separation step at a temperature of 50°C or higher and 150°C or lower to desorb carbon dioxide from the carbon dioxide absorbent that has absorbed the carbon dioxide, thereby regenerating the carbon dioxide absorbent and capturing the desorbed carbon dioxide.

[0046] In the carbon dioxide separation method of the present invention and the carbon dioxide separation and capture method of the present invention, the step of separating carbon dioxide from a mixed gas containing carbon dioxide is the carbon dioxide separation step (A) in both cases, and they are the same.

[0047] The carbon dioxide separation step (A) is a step of bringing a mixed gas containing carbon dioxide into contact with the carbon dioxide absorbent of the present invention, thereby causing the carbon dioxide absorbent of the present invention to absorb carbon dioxide in the mixed gas.

[0048] The carbon dioxide separation step (A) may, for example, be a step in which a mixed gas containing carbon dioxide is supplied to an absorbent-packed column or absorbent-packed tower packed with the carbon dioxide absorbent of the present invention, and the mixed gas is brought into contact with the carbon dioxide absorbent to allow the carbon dioxide absorbent to absorb the carbon dioxide in the mixed gas, thereby separating carbon dioxide from the mixed gas. In this form of carbon dioxide separation step (A), the mixed gas is supplied to the absorbent-packed column or absorbent-packed tower to bring the mixed gas into contact with the carbon dioxide absorbent, and the mixed gas after contact with the carbon dioxide absorbent in the absorbent-packed column or absorbent-packed tower is discharged from the absorbent-packed column or absorbent-packed tower. The method for packing the absorbent of the present invention into the absorbent-packed column or absorbent-packed tower is not particularly limited, and may be carried out under atmospheric pressure or reduced pressure.

[0049] The temperature of the carbon dioxide absorbent in the carbon dioxide separation step (A) is not limited as long as the carbon dioxide absorbent can exhibit its function, but is preferably −20° C. or higher and 60° C. or lower, particularly 0° C. or higher and 40° C. or lower, from the viewpoint of more efficient absorption of carbon dioxide.

[0050] The pressure (absolute pressure) in the carbon dioxide separation step (A) is not particularly limited, and the step can be carried out under atmospheric pressure.

[0051] In the carbon dioxide separation step (A), a mixed gas containing carbon dioxide is brought into contact with the carbon dioxide absorbent, whereby the carbon dioxide in the mixed gas is absorbed by the carbon dioxide absorbent of the present invention, and the carbon dioxide can be separated from the mixed gas. In the carbon dioxide separation step (A), a carbon dioxide absorbent having absorbed carbon dioxide is obtained.

[0052] The carbon dioxide separation and capture method of the present invention includes a carbon dioxide capture step (B) of regenerating the carbon dioxide absorbent that has absorbed carbon dioxide in the carbon dioxide separation step and capturing carbon dioxide. The carbon dioxide recovery step (B) is a step of heating the carbon dioxide absorbent that has absorbed carbon dioxide in the carbon dioxide separation step (A) to desorb carbon dioxide from the carbon dioxide absorbent that has absorbed carbon dioxide.

[0053] The carbon dioxide recovery step (B) may, for example, be carried out after the carbon dioxide separation step (A), by heating the carbon dioxide absorbent packed in the absorbent-packed column or absorbent-packed tower to regenerate the carbon dioxide absorbent and recover the desorbed carbon dioxide.

[0054] In the carbon dioxide recovery step (B), the heating temperature of the carbon dioxide absorbent is 50°C or higher and 150°C or lower, preferably 80°C or higher and 140°C or lower. Generally, the higher the heating temperature, the easier it is for carbon dioxide to be desorbed from the carbon dioxide absorbent that has absorbed carbon dioxide. The carbon dioxide absorbent of the present invention can desorb carbon dioxide at a temperature of 50°C or higher and 150°C or lower, preferably 80°C or higher and 140°C or lower, and at a temperature equal to or higher than the temperature in the carbon dioxide separation step (A). For example, when the carbon dioxide absorbent is the carbon dioxide absorbent of the present invention, the heating temperature is preferably 80 to 120°C.

[0055] In the carbon dioxide recovery step (B), the pressure (absolute pressure) is not particularly limited, and the step may be performed under atmospheric pressure or under reduced pressure. When the step is performed under reduced pressure, the pressure (absolute pressure) is 85 kPa or less, preferably 60 kPa or less, from the viewpoint of preventing oxidation of the carbon dioxide absorbent, and more preferably 50 kPa or less, more preferably 10 kPa or less, and particularly preferably 4 kPa or less, from the viewpoint of efficiently desorbing carbon dioxide from the carbon dioxide absorbent.

[0056] In the carbon dioxide separation and capture method of the present invention, the carbon dioxide separation step (A) and the carbon dioxide capture step (B) can be repeated two or more times by using the regenerated carbon dioxide absorbent obtained by performing the carbon dioxide capture step (B) as the carbon dioxide absorbent with which the mixed gas containing carbon dioxide is contacted in the carbon dioxide separation step (A). For example, when the carbon dioxide separation step (A) and the carbon dioxide capture step (B) are repeated twice, they are performed in the following order: carbon dioxide separation step (A) → carbon dioxide capture step (B) → carbon dioxide separation step (A) → carbon dioxide capture step (B). Then, the carbon dioxide separation step (A) and the carbon dioxide capture step (B) can be repeated as long as the carbon dioxide absorption performance is maintained.

[0057] In the carbon dioxide separation method and carbon dioxide separation and capture method of the present invention, the carbon dioxide absorbent of the present invention containing the phosphine oxide compound represented by general formula (1), which has excellent chemical absorption properties, is used for absorbing carbon dioxide, and therefore the efficiency of removing carbon dioxide from a mixed gas can be increased.

[0058] The carbon dioxide separation method and carbon dioxide separation and capture method of the present invention are suitably used when separating or separating and capturing carbon dioxide from a carbon dioxide-containing mixed gas emitted from, for example, power plants such as coal-fired power plants and natural gas-fired power plants, factories such as chemical plants, waste treatment facilities and steelworks, transportation equipment such as automobiles, aircraft and ships, etc. They are also suitably used when separating or separating and capturing carbon dioxide directly from the atmosphere, for example. [Example]

[0059] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0060] (Synthesis Example 1: Tris(3-aminopropyl)phosphine oxide) A 1 L stainless steel autoclave equipped with a stirrer, thermometer, pressure pump, safety valve, and gas inlet tube was charged with 150 ml of toluene and 133 g (2.33 mol) of allylamine, and the autoclave was purged with nitrogen gas and vacuum three times. 22 g (0.65 mol) of 99.9% pure phosphine gas manufactured by Nippon Chemical Industry Co., Ltd. was then charged. When the temperature was raised to 80°C in a hot water bath, the gauge pressure was 0.93 MPa (absolute pressure 1.03 MPa). Next, 1.06 g (0.006 mol) of azobisisobutyronitrile was dissolved in 150 ml of toluene, injected in portions over 6 hours, and aged overnight at 80 °C. At this time, the gauge pressure was 0.01 MPa (absolute pressure 0.11 MPa). After overnight aging, the mixture was cooled to room temperature, and the remaining gas was vented to a decompression facility. The system was then purged with nitrogen gas and vacuum. The mixture was then extracted into a reduced-pressure eggplant-shaped flask, yielding 585 g of a colorless, transparent liquid. Next, the obtained colorless transparent liquid was heated under reduced pressure (gauge pressure 4 kPa (absolute pressure 105.3 kPa), 80°C) to distill off excess allylamine and toluene, and the degree of vacuum and temperature were further increased to heat (gauge pressure 0.2 kPa (absolute pressure 101.5 kPa), 160°C). When the initial distillate began to appear, heating was stopped and the residue was used as the product. The resulting product was cooled to room temperature and then purged with nitrogen gas to yield 120 g of a colorless, transparent liquid. The NMR identification data for the resulting colorless, transparent liquid are as follows: (Identification data) 31 P-NMR(DO); -29.73 ppm 1 H-NMR(D2O); 1.40~1.46ppm(m, 6H, -CH2-), 1.52~1.61ppm(m, 6H, P-CH2-), 2.63~2.71ppm(m, 6H, -CH2-NH2), 4.67ppm(s, 6H, -NH2) As a result, it was confirmed that the compound was tris(3-aminopropyl)phosphine.

[0061] Next, a 1L four-neck flask equipped with a stirrer and thermometer was purged with nitrogen gas, and 92.4g (0.45 mol) of the obtained tris(3-aminopropyl)phosphine and 500ml of pure water were charged. 56.1g (0.495 mol) of 30% hydrogen peroxide diluted with 100ml of pure water was added dropwise over 1 hour while maintaining the temperature at 70-75°C. After the dropwise addition, the mixture was aged for 1 hour, cooled to room temperature, and concentrated under reduced pressure in an evaporator to remove water, yielding 100.8g of a colorless, transparent liquid. The NMR identification data of the obtained colorless, transparent liquid is as follows: (Identification data) 31 P-NMR(DO); 60.77 ppm 1 H-NMR(D2O); 1.50~1.58ppm(m, 6H, -CH2-), 1.71~1.77ppm(m, 6H, P-CH2-), 2.57~2.60ppm(t, 6H, -CH2-NH2), 4.70ppm(s, 6H, -NH2) As a result, it was confirmed that the compound was tris(3-aminopropyl)phosphine oxide.

[0062] (Synthesis Example 2: Tributyl(3-aminopropyl)phosphonium·β-alanine) A glass column (inner diameter 65 mm, length 500 mm) was packed with 1500 ml of ion exchange resin (Amberlite IRA400J Cl, manufactured by Organo Corporation, exchange capacity 1.4 equivalents / resin volume L), and 1000 ml of an aqueous solution containing 80 g (2.0 mol) of sodium hydroxide was passed through it from above using a tube pump at a rate of SV = 1.0, followed by the addition of pure water until the effluent became neutral. Next, 140.0 g (0.41 mol) of tributyl(3-aminopropyl)phosphonium bromide dissolved in 500 mL of purified water was passed through the column at a flow rate of SV = 1.0. 1000 mL of purified water was then passed through the column, yielding 1550 g of an aqueous solution of tributyl(3-aminopropyl)phosphonium hydroxide. Neutralization titration with 1 / 10 N hydrochloric acid titrant revealed a concentration of 6.5% and a yield of 89.0%. 10.7 g (0.12 mol) of β-alanine was dissolved in 500 g (0.12 mol) of the resulting aqueous solution of tributyl(3-aminopropyl)phosphonium hydroxide at room temperature. The resulting mixed solution was concentrated under reduced pressure using an evaporator, and the concentrated solution was mixed with methanol. The resulting methanol solution was dehydrated overnight over anhydrous magnesium sulfate, and the dehydrated methanol solution was concentrated under reduced pressure using an evaporator to obtain 41.4 g (crude yield 99.0%) of a colorless, transparent, viscous liquid with a viscosity (25°C) of 288 cP. The NMR identification data for the resulting colorless, transparent, viscous liquid are as follows: (Identification data) 31 P-NMR: 34.34 ppm 1 H-NMR;0.80ppm(t,9H,-CH3),1.31~1.45ppm(m,12H,-CH2-),1.54~1.59ppm(m,2H,-CH2-)2.03~2.08ppm(m,8H,P-CH2-),2.19ppm(t, 2H,-CH2-COO),2.58,2.69ppm(t,2H,-CH2-NH2),3.20,3.21ppm(s,-NH2) As a result, it was confirmed that the compound was tributyl(3-aminopropyl)phosphonium·β-alanine.

[0063] Example 1 38.0 g (0.172 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 300 ml of pure water and silica gel (CARiACT Q-30 manufactured by Fuji Silysia Chemical Ltd., particle size 1.70 to 4.00 mm, BET specific surface area 100 m 2 70.0 g of silica gel (3-aminopropyl)phosphine oxide (70.0 g / g, average pore diameter 30 nm) was added and allowed to stand at room temperature until the silica gel became moisture permeable. The added water was completely distilled off by concentrating under reduced pressure using an evaporator, thereby obtaining 108.9 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 35.0 mass %. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 1, Carbon Dioxide Absorption Test 2, and Regeneration Test 1, which will be described later.

[0064] Example 2 28.7 g (0.13 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 300 ml of pure water and silica gel (CARiACT Q-30 manufactured by Fuji Silysia Chemical Ltd., particle size 1.70 to 4.00 mm, BET specific surface area 100 m 2 85.0 g of silica gel (3-aminopropyl)phosphine oxide (30 nm / g, average pore diameter) was added and left to stand at room temperature until the silica gel became moisture permeable. The added water was completely distilled off by concentrating under reduced pressure using an evaporator, yielding 114.3 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 25.0 mass %. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 2, which will be described later.

[0065] Example 3 33.2 g (0.15 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 300 ml of pure water and silica gel (CARiACT Q-30 manufactured by Fuji Silysia Chemical Ltd., particle size 1.70 to 4.00 mm, BET specific surface area 100 m 2 40.6 g of silica gel (30 nm / g, average pore size 30 nm) was added and left to stand at room temperature until the silica gel became moisture permeable. The added water was completely distilled off by concentrating under reduced pressure using an evaporator, yielding 74.3 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 45.0 mass %. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 2, which will be described later.

[0066] Example 4 33.2 g (0.15 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 300 ml of pure water and silica gel (CARiACT Q-30 manufactured by Fuji Silysia Chemical Ltd., particle size 1.70 to 4.00 mm, BET specific surface area 100 m 2 54.2 g of silica gel (3-aminopropyl)phosphine oxide (1.0 g / g, average pore diameter 30 nm) was added and left to stand at room temperature until the silica gel became moisture permeable. The added water was completely distilled off by concentrating under reduced pressure using an evaporator, yielding 87.4 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 38.0 mass %. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 2, which will be described later.

[0067] Example 5 33.2 g (0.15 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 300 ml of pure water and silica gel (CARiACT Q-50 manufactured by Fuji Silysia Chemical Ltd., particle size 1.70 to 4.00 mm, BET specific surface area 80 m 261.7 g of silica gel (3-aminopropyl)phosphine oxide (3-aminopropyl-1,1-dihydro ...

[0068] Example 6 33.2 g (0.15 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 300 ml of pure water and silica gel (CARiACT Q-50 manufactured by Fuji Silysia Chemical Ltd., particle size 1.70 to 4.00 mm, BET specific surface area 80 m 2 54.2 g of silica gel (3-aminopropyl)phosphine oxide (1 / g, average pore diameter 50 nm) was added and left to stand at room temperature until the silica gel became moisture permeable. The added water was completely distilled off by concentrating under reduced pressure using an evaporator, yielding 87.5 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 38.0 mass %. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 2, which will be described later.

[0069] Example 7 33.2 g (0.15 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 300 ml of pure water and silica gel (CARiACT Q-50 manufactured by Fuji Silysia Chemical Ltd., particle size 1.70 to 4.00 mm, BET specific surface area 80 m 249.8 g of silica gel (3-aminopropyl)phosphine oxide (3-aminopropyl-1,1-dihydro ...

[0070] Example 8 Tris(3-aminopropyl)phosphine oxide (22.1 g (0.1 mol)) obtained in Synthesis Example 1 was dissolved in 200 ml of pure water and added to 192.5 g of granular activated carbon Shirasagi G2c (manufactured by Osaka Gas Chemicals Co., Ltd.) having a particle size of 4 to 8 mesh at room temperature. While rotating in an evaporator, the degree of vacuum was gradually increased to completely distill off water until the weight reached a constant value, thereby obtaining 214.6 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto activated carbon. The impregnation ratio of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 10.3 mass %. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 1, which will be described later.

[0071] Example 9 22.1 g (0.1 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 100 ml of pure water, and then powdered silica gel (CARPLEX BS-510BX manufactured by Evonik Japan Co., Ltd., average particle size 10.5 μm, BET specific surface area 290 m / g, average pore diameter 10 nm, pore volume 1.5 cm) was added. 3 51.6 g of tris(3-aminopropyl)phosphine oxide (1.6 g / g) was added and the mixture was left to stand at room temperature until the silica gel was moisture permeable. The added water was completely distilled off by concentrating under reduced pressure using an evaporator, thereby obtaining 74.0 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 30.0 mass%. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 3, which will be described later.

[0072] Example 10 22.1 g (0.1 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 100 ml of pure water, and then powdered silica gel (CARPLEX BS-510BX manufactured by Evonik Japan Co., Ltd., average particle size 10.5 μm, BET specific surface area 290 m) was added. 2 / g, average pore diameter 10 nm, pore volume 1.5 cm 3 33.2 g of tris(3-aminopropyl)phosphine oxide (1 / g) was added, and the mixture was left to stand at room temperature until the silica gel was moisture-permeable. The mixture was concentrated under reduced pressure using an evaporator to completely remove the added water, thereby obtaining 55.9 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 40.0 mass %. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 3, which will be described later.

[0073] Example 11 22.1 g (0.1 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 100 ml of pure water, and then powdered silica gel (CARPLEX BS-510BX manufactured by Evonik Japan Co., Ltd., average particle size 10.5 μm, BET specific surface area 290 m) was added. 2 / g, average pore diameter 10 nm, pore volume 1.5 cm 3 27.0 g of tris(3-aminopropyl)phosphine oxide (1 / g) was added and the mixture was left to stand at room temperature until the silica gel was moisture permeable. The mixture was concentrated under reduced pressure using an evaporator to completely remove the added water, thereby obtaining 49.8 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 45.0 mass%. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 3, which will be described later.

[0074] Example 12 22.1 g (0.1 mol) of tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in 100 ml of pure water, and then powdered silica gel (CARPLEX BS-510BX manufactured by Evonik Japan Co., Ltd., average particle size 10.5 μm, BET specific surface area 290 m) was added. 2 / g, average pore diameter 10 nm, pore volume 1.5 cm 3 18.1 g of silica gel (3-aminopropyl)phosphine oxide / g) was added and the mixture was left to stand at room temperature until the silica gel was moisture permeable. The mixture was concentrated under reduced pressure using an evaporator to completely remove the added water, thereby obtaining 40.5 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated onto silica gel. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 55.0 mass%. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 3, which will be described later.

[0075] Example 13 The tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in pure water to obtain a 40% aqueous solution of tris(3-aminopropyl)phosphine oxide. Next, the powdered silica gel used in Example 9 (CARPLEX BS-510BX manufactured by Evonik Japan Co., Ltd., average particle size 10.5 μm, BET specific surface area 290 m) was added. 2 / g, average pore diameter 10 nm, pore volume 1.5 cm 3 A mixture of 52% by mass of silica (mesoporous silica / g) and 48% by mass of clay mineral containing alumina was uniformly kneaded, then cut into 5 mm square dice and fired at 500°C to obtain dice-shaped pellets that were a composite of alumina and mesoporous silica. 4.97 g of the obtained diced pellets were immersed in a 40% aqueous solution (6.73 g) of tris(3-aminopropyl)phosphine oxide, and the water was completely removed using an evaporator to obtain 7.66 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated into a composite of alumina and mesoporous silica. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 35.0 mass %. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 4, which will be described later.

[0076] Example 14 The tris(3-aminopropyl)phosphine oxide obtained in Synthesis Example 1 was dissolved in pure water to obtain a 35% aqueous solution of tris(3-aminopropyl)phosphine oxide. Next, the powdered silica gel used in Example 9 (CARPLEX BS-510BX manufactured by Evonik Japan Co., Ltd., average particle size 10.5 μm, BET specific surface area 290 m) was added. 2 / g, average pore diameter 10 nm, pore volume 1.5 cm 3 A mixture of 52 mass% of silica (mesoporous silica / g) and 48 mass% of clay mineral containing alumina was uniformly kneaded, and then extrusion-molded using a mold with a diameter of 3 mm and 200 cells (lattice: 1.4 mm, slit width: 0.4 mm, pitch: 1.8 mm) and fired at 500°C to obtain a honeycomb-shaped molded product of alumina and mesoporous silica, measuring φ30 mm and t15 mm. The obtained honeycomb-shaped molded articles (3.93 g per article) were immersed overnight in a 35% aqueous solution of tris(3-aminopropyl)phosphine oxide, and then vacuum-dried at 100°C using a vacuum oven to completely remove moisture, yielding 5.89 g of a carbon dioxide absorbent in which tris(3-aminopropyl)phosphine oxide was impregnated into a composite of alumina and mesoporous silica. The impregnation rate of tris(3-aminopropyl)phosphine oxide relative to the total mass of the carbon dioxide absorbent was 33.0 mass%. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 5 and Regeneration Test 2, which will be described later.

[0077] (Reference example 1) 30.2 g (0.086 mol) of tributyl(3-aminopropyl)phosphonium β-alanine obtained in Synthesis Example 2 was dissolved in 300 ml of pure water and then added to silica gel (Fuji Silysia Chemical Ltd., CAriACT Q-30, particle size 1.70 to 4.00 mm, BET specific surface area 100 m 255.9 g of silica gel (wt. / g, average pore size 30 nm) was added and left to stand at room temperature until the silica gel became moisture permeable. The added water was completely removed by vacuum concentration using an evaporator, yielding 86.3 g of a carbon dioxide absorbent in which tributyl(3-aminopropyl)phosphonium·β-alanine was impregnated onto the silica gel. The impregnation rate of tributyl(3-aminopropyl)phosphonium·β-alanine relative to the total mass of the carbon dioxide absorbent was 35.0 mass%. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 1 and Carbon Dioxide Absorption Test 2, which will be described later.

[0078] (Reference example 2) Tributyl(3-aminopropyl)phosphonium·β-alanine (34.9 g (0.1 mol)) obtained in Synthesis Example 2 was dissolved in 150 ml of pure water and added to 287.1 g of granular activated carbon Shirasagi G2c (Osaka Gas Chemicals Co., Ltd.) with a particle size of 4 to 8 mesh at room temperature. While rotating the evaporator, the degree of vacuum was gradually increased to completely distill off the water until the weight reached a constant value, yielding 332.7 g of a carbon dioxide absorbent in which tributyl(3-aminopropyl)phosphonium·β-alanine was impregnated onto the activated carbon. The impregnation rate of tributyl(3-aminopropyl)phosphonium·β-alanine relative to the total mass of the carbon dioxide absorbent was 10.8 mass%. The obtained carbon dioxide absorbent was evaluated in Carbon Dioxide Absorption Test 1, which will be described later.

[0079] (evaluation) (Carbon dioxide absorption test 1) 90 ml of the carbon dioxide absorbents obtained in Example 1 and Reference Example 1 were packed into a glass column with an inner diameter of 20 mm and a length of 300 mm, and atmospheric air (room temperature 25°C, average carbon dioxide concentration: 450 ppm) was passed through the column at a flow rate of 100 ml / min using an air pump. The carbon dioxide concentration at the outlet of the glass column was measured and recorded using a data logger carbon dioxide measuring device (TR-76Ui-S, manufactured by T&D Corporation), and the time until saturation was reached and the carbon dioxide concentration began to increase (breakthrough time) was determined. The number of moles of absorbed carbon dioxide was calculated by taking the difference between the average carbon dioxide concentration in the room and the average carbon dioxide concentration at the outlet as the amount of carbon dioxide absorbed. The absorption capacity was determined as the amount of carbon dioxide absorbed per gram of carbon dioxide absorbent. The results are shown in Table 1. The same procedure was also carried out for the carbon dioxide absorbents obtained in Example 8 and Reference Example 2, and the results are shown in Table 2.

[0080] [Table 1]

[0081] [Table 2]

[0082] The results shown in Table 1 show that the carbon dioxide absorbent of Example 1 is superior to the carbon dioxide absorbent of Reference Example 1 in carbon dioxide absorption performance. Furthermore, it is clear from the results shown in Table 2 that the carbon dioxide absorbent of Example 8 is superior to the carbon dioxide absorbent of Reference Example 2 in terms of carbon dioxide absorption performance.

[0083] (Carbon dioxide absorption test 2) The carbon dioxide absorbents obtained in Examples 1 to 7 and Reference Example 1 were placed in 35 ml Erlenmeyer flasks, weighed accurately to the nearest 0.1 mg, and 99.995% pure carbon dioxide gas was blown into the flask at a flow rate of 200 ml / min at room temperature (25°C). The weight was measured accurately to the nearest 0.1 mg every 10 minutes, and gas blowing was terminated when the weight reached equilibrium. The increased weight was used as the amount of carbon dioxide absorbed, and the number of moles was calculated. The absorption capacity was calculated as the amount of carbon dioxide absorbed per gram of carbon dioxide absorbent. The results are shown in Table 3.

[0084] [Table 3]

[0085] The results shown in Table 3 show that the carbon dioxide absorbents of Examples 1 to 7 are superior to the carbon dioxide absorbent of Reference Example 1 in terms of carbon dioxide absorption performance.

[0086] (Carbon dioxide absorption test 3) The carbon dioxide absorbents obtained in Examples 9 to 12 were placed in 35 ml Erlenmeyer flasks, weighed accurately to the nearest 0.1 mg, and padded with absorbent cotton to prevent the powdered sample from being carried away by the air current and being discharged outside the system. Carbon dioxide gas with a purity of 99.995% was blown into the flask at a flow rate of 200 ml / min at room temperature (25°C). The weight was measured accurately to the nearest 0.1 mg every 10 minutes, and gas blowing was terminated when the weight reached equilibrium. The increased weight was used as the amount of carbon dioxide absorbed, and the number of moles was calculated. The absorption capacity was calculated as the amount of carbon dioxide absorbed per gram of carbon dioxide absorbent. Furthermore, any remaining carbon dioxide in the absorbent cotton was purged with nitrogen gas. The results are shown in Table 4.

[0087] [Table 4]

[0088] The results shown in Table 4 show that the carbon dioxide absorbents of Examples 9 to 12 are superior to the carbon dioxide absorbent of Reference Example 3 in terms of carbon dioxide absorption performance.

[0089] (Carbon dioxide absorption test 4) The carbon dioxide absorbent obtained in Example 13 was placed in a 35 ml Erlenmeyer flask, weighed accurately to the nearest 0.1 mg, and 99.995% pure carbon dioxide gas was blown into it at a flow rate of 100 ml / min at room temperature (25°C) for 10 minutes, after which the weight was measured accurately to the nearest 0.1 mg. The increased weight was used as the amount of carbon dioxide absorbed, and the number of moles was calculated. The absorption capacity was calculated as the amount of carbon dioxide absorbed per gram of carbon dioxide absorbent. The results are shown in Table 5.

[0090] [Table 5]

[0091] The results shown in Table 5 show that the carbon dioxide absorbent of Example 13 has excellent carbon dioxide absorption performance.

[0092] (Carbon dioxide absorption test 5) The carbon dioxide absorbent obtained in Example 14 was placed in a 100 ml glass screw-cap bottle, weighed accurately to the nearest 0.1 mg, and 99.995% pure carbon dioxide gas was blown into it at a flow rate of 100 ml / min at room temperature (25°C) for 10 minutes, after which the weight was measured accurately to the nearest 0.1 mg. The remaining carbon dioxide in the bottle was then purged with nitrogen gas. The increased weight was used as the amount of carbon dioxide absorbed, and the number of moles was calculated. The absorption capacity was calculated as the amount of carbon dioxide absorbed per gram of carbon dioxide absorbent. The results are shown in Table 6.

[0093] [Table 6]

[0094] The results shown in Table 6 show that the carbon dioxide absorbent of Example 14 has excellent carbon dioxide absorption performance.

[0095] (Regeneration test 1) The carbon dioxide absorbent obtained in Example 1 was packed into a 190 ml stainless steel clean pipe, and carbon dioxide gas with a purity of 99.995% was passed through it at a flow rate of 500 ml / min for 10 minutes to absorb the carbon dioxide. The weight was measured before and after the passage of air, and the increase in weight was used as the amount of carbon dioxide absorbed, from which the number of moles was calculated. The absorption capacity was determined as the amount of carbon dioxide absorbed per gram of the carbon dioxide absorbent. The carbon dioxide absorbent that had absorbed carbon dioxide was placed in a 200 mm diameter petri dish and heated at 120°C and a gauge pressure of 0.2 kPa (absolute pressure 101 kPa) for 90 minutes to expel the carbon dioxide and perform regeneration. The regenerated carbon dioxide absorbent was then packed into the stainless steel clean pipe again, and the carbon dioxide absorption and regeneration were repeated five times. The regeneration rate was calculated based on the following formula. The results are shown in Table 7. Regeneration rate (%) = (absorption capacity at regeneration / initial absorption capacity) x 100

[0096] [Table 7]

[0097] The results shown in Table 7 show that the regenerated carbon dioxide absorbent, which was obtained by heating the carbon dioxide absorbent after the initial carbon dioxide absorption test and expelling the carbon dioxide, regained its ability to absorb carbon dioxide, and even the regenerated carbon dioxide absorbent had excellent absorption performance and regeneration rate.

[0098] (Regeneration test 2) The carbon dioxide absorbent obtained in Example 14 was used to absorb carbon dioxide by the same procedure as in Carbon Dioxide Absorption Test 5. The weight was measured before and after aeration, and the increased weight was taken as the amount of carbon dioxide absorbed, and the number of moles was calculated. The absorption capacity was determined as the amount of carbon dioxide absorbed per gram of the carbon dioxide absorbent. The carbon dioxide absorbent that had absorbed carbon dioxide was placed in a stainless steel tray and heated in a vacuum oven at 100°C and a gauge pressure of -0.1 MPa (absolute pressure 0.001 MPa) for 90 minutes to expel the carbon dioxide and perform regeneration. The regenerated carbon dioxide absorbent was then placed back into the 100 ml glass screw-cap bottle, and the carbon dioxide absorption and regeneration process was repeated twice. The regeneration rate was calculated using the following formula. The results are shown in Table 8. Regeneration rate (%) = (absorption capacity at regeneration / initial absorption capacity) x 100

[0099] [Table 8]

[0100] The results shown in Table 8 show that the regenerated carbon dioxide absorbent, which was obtained by heating the carbon dioxide absorbent after the initial carbon dioxide absorption test and expelling the carbon dioxide, regained its ability to absorb carbon dioxide, and even the regenerated carbon dioxide absorbent had excellent absorption performance and regeneration rate.

Claims

1. The following general formula (1): 【Chemical 1】 (In the formula, a, b, and c represent integers of 1 or more and 10 or less, and R １ , R ２ and R ３ each independently represents an amino group or a hydroxy group, R １ , R ２ and R ３ At least one of the groups is an amino group. and a phosphine oxide compound represented by the formula: a porous carrier supporting the phosphine oxide compound; A carbon dioxide absorbent comprising:

2. In the general formula (1), R １ , R ２ and R ３ 2. The carbon dioxide absorbent according to claim 1, wherein each of the groups is an amino group.

3. 3. The carbon dioxide absorbent according to claim 1, wherein the porous carrier is activated carbon, silica gel, layered silicate, mesoporous silica, zeolite, vermiculite, molecular sieve, porous silica, diatomaceous earth, porous resin, porous fiber, porous metal-organic framework, porous alumina, porous ceramic, porous concrete, activated clay, clay mineral, or a composite thereof.

4. 3. A carbon dioxide separation method comprising: a carbon dioxide separation step of contacting a mixed gas containing carbon dioxide with the carbon dioxide absorbent according to claim 1 or 2 to cause the carbon dioxide absorbent to absorb the carbon dioxide in the mixed gas, thereby separating carbon dioxide from the mixed gas.

5. a carbon dioxide separation step of contacting a mixed gas containing carbon dioxide with the carbon dioxide absorbent according to claim 1 or 2 to cause the carbon dioxide absorbent to absorb the carbon dioxide in the mixed gas, thereby separating carbon dioxide from the mixed gas; a carbon dioxide recovery step of heating the carbon dioxide absorbent that has absorbed carbon dioxide in the carbon dioxide separation step at a temperature of 50°C or higher and 150°C or lower to desorb carbon dioxide from the carbon dioxide absorbent that has absorbed carbon dioxide, thereby regenerating the carbon dioxide absorbent and recovering the desorbed carbon dioxide; A carbon dioxide separation and capture method comprising the steps of:

6. 6. The method for separating and capturing carbon dioxide according to claim 5, wherein the carbon dioxide separation step and the carbon dioxide capture step are repeated two or more times by using a regenerated carbon dioxide absorbent obtained by performing the carbon dioxide capture step as the carbon dioxide absorbent with which the mixed gas containing carbon dioxide is brought into contact in the carbon dioxide separation step.

7. 3. An apparatus comprising the carbon dioxide absorbent according to claim 1 or 2.

8. 8. The apparatus of claim 7, wherein the apparatus is used in a power plant, a factory, or a transportation facility.

9. 8. The device of claim 7, wherein the device is a DAC device.

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