Bridged ring organic polyamine, preparation method and application

Abstract

The invention provides bridged ring organic polyamine as well as a preparation method and application thereof, and relates to the technical field of carbon dioxide capture. According to the bridged ring organic polyamine provided by the invention, the synergistic effect of a plurality of secondary amine and tertiary amine active groups embedded in a bridged ring skeleton structure is utilized to realize intramolecular rapid proton migration in a carbon dioxide chemical absorption process, so that the dual effects of improving the absorption reaction rate and the absorption capacity are achieved. The invention provides a bridged ring organic polyamine absorbent which consists of bridged ring organic polyamine and water and has the advantages of high carbon dioxide absorption rate and high absorption capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture, and particularly relates to a bridged-ring organic polyamine absorbent, a preparation method and an application thereof. Background Art

[0002] Carbon dioxide is the primary greenhouse gas. Excessive emissions of industrial waste gases will cause a sharp increase in the atmospheric carbon dioxide concentration, resulting in climate change represented by global warming. Carbon capture, utilization and storage technology (CCUS) is the most effective countermeasure to deal with excessive industrial carbon dioxide emissions at present, and can capture carbon dioxide in industrial waste gases and convert it into chemical raw materials and fine chemicals. A fast, high-capacity, low-energy-consumption and low-loss carbon capture process constitutes the material basis of CCUS technology and is also the fundamental prerequisite for determining the development and implementation of CCUS technology.

[0003] The chemical absorption method of carbon dioxide relying on amine solutions (Reaction formula 1) is the most mature and widely used carbon capture strategy in the industrial field at present. It has the advantages of fast response, high carbon dioxide selectivity, simple equipment and low amine solution cost. Many demonstration plants have been completed by relevant enterprises at home and abroad. However, due to the limitations of the structure of amine absorbents themselves, the amine group content in their molecules is relatively low. Most amine molecules contain only one active amine group in their structures, which limits their potential for targeted structural improvement in terms of carbon dioxide absorption rate and absorption capacity.

[0004] Reaction formula 1:

[0005]

[0006] The above-mentioned essential disadvantages at the molecular level have become bottlenecks that are difficult to overcome in the structural modification and further optimization of amine-based carbon dioxide chemical absorbents. Therefore, the academic and industrial circles urgently need to design and develop a new chemical absorption system with higher absorption rate and absorption capacity in order to fundamentally solve the deficiency of amine molecules in terms of reaction activity. Summary of the Invention

[0007] The purpose of the present invention is to provide a bridged-ring organic polyamine, a preparation method and an application thereof. The bridged-ring organic polyamine absorbent provided by the present invention has the advantages of fast carbon dioxide absorption rate and high absorption capacity.

[0008] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0009] The present invention provides a bridged-ring organic polyamine having the structure shown in Formula I:

[0010]

[0011] In Formula I, R 1 and R2 Independently H or C1-C3 alkyl.

[0012] Furthermore, it has the structure shown in any one of Formula I-1 to Formula I-15:

[0013]

[0014] The present invention provides a method for preparing the bridged-ring organic polyamine described in the above solution, including the following steps:

[0015] Mix compound 1, diethanolamine and a transition metal catalyst in an ether organic solvent, then introduce hydrogen, and carry out a high-temperature and high-pressure alkylation reaction to obtain the bridged-ring organic polyamine;

[0016]

[0017] In the compound 1, R 1 and R 2 Independently H or C1-C3 alkyl.

[0018] Furthermore, the present invention preferably first dissolves compound 1 in an ether organic solvent, then adds diethanolamine, the ether organic solvent in which compound 1 is dissolved and a transition metal catalyst into a high-pressure reaction kettle, seals the reaction kettle and purges the air in the kettle with nitrogen, and after the purging is completed, introduces hydrogen and carries out a high-temperature and high-pressure alkylation reaction.

[0019] Furthermore, in the present invention, the high-temperature and high-pressure alkylation reaction is preferably carried out under stirring conditions. The present invention has no special requirements for the stirring rate, and specifically it is 500 r / min in the examples of the present invention.

[0020] Furthermore, after completing the high-temperature and high-pressure alkylation reaction, the present invention preferably cools the obtained reaction liquor and filters it, washes the filter cake with an ether organic solvent, combines the washing liquid and the filtrate, removes the solvent completely by using a rotary evaporator, and performs vacuum distillation to obtain the bridged-ring organic polyamine.

[0021] Furthermore, the molar ratio of compound 1 to diethanolamine is 1:(0.2-5), preferably 1:(0.5-2), more preferably 1:(0.8-1.5).

[0022] Furthermore, the transition metal catalyst is a copper-based catalyst or a nickel-based catalyst. The copper-based catalyst is preferably Raney copper or copper powder; the nickel-based catalyst is preferably Raney nickel or nickel powder; the mass of the transition metal catalyst is 0.1-35% of the total mass of compound 1 and diethanolamine, preferably 0.5-25%, more preferably 5-20%.

[0023] Further, the ether organic solvent is one or more of ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, and methyl tert-butyl ether. There are no special requirements for the dosage of the ether organic solvent in the present invention, as long as it can dissolve the raw materials.

[0024] Further, the temperature of the high-temperature and high-pressure alkylation reaction is 100 - 320 °C, preferably 120 - 280 °C, more preferably 150 - 240 °C; the time of the high-temperature and high-pressure alkylation reaction is 1 - 36 h, preferably 5 - 30 h, more preferably 12 - 24 h; the hydrogen pressure is 0.1 - 12 MPa, preferably 3 - 6 MPa.

[0025] The present invention provides the use of the bridged-ring organic polyamine described in the above solution or the bridged-ring organic polyamine prepared by the preparation method described in the above solution as an absorbent in the absorption of carbon dioxide.

[0026] Further, when the bridged-ring organic polyamine absorbent provided by the present invention is used to absorb carbon dioxide, the volume concentration of carbon dioxide in the mixed gas stream is preferably 1 - 85%, the pressure of the mixed gas stream is preferably 0.05 - 5 MPa; the absorption temperature is preferably 15 - 65 °C, and the regeneration temperature of the absorbent is preferably 80 - 120 °C.

[0027] Further, the present invention has no special requirements for the source of the carbon dioxide-containing mixed gas stream, and any well-known source in the art can be used, such as power plant flue gas, refinery tail gas, steel mill tail gas, cement plant tail gas, petrochemical plant tail gas, water gas, biogas, natural gas, or carbonate ore decomposition gas. By absorbing carbon dioxide, the present invention can achieve the purpose of capturing carbon dioxide or removing carbon dioxide from the carbon dioxide-containing mixed gas stream.

[0028] The present invention provides a bridged-ring organic polyamine absorbent, which, by mass percentage, comprises 1 - 50% (specifically, it can be 10%, 15%, 20%, 25%, 30%, 40%, 50%, and will not be enumerated here) of the bridged-ring organic polyamine described in the above solution or the bridged-ring organic polyamine prepared by the preparation method described in the above solution, and 50 - 99% of water. In the examples of the present invention, the bridged-ring organic polyamine absorbent is composed of 30% by mass of the bridged-ring organic polyamine and 70% by mass of water.

[0029] Further, the present invention has no special requirements for the preparation method of the bridged-ring organic polyamine absorbent, and it can be directly prepared by mixing the bridged-ring organic polyamine and water evenly.

[0030] The bridged-ring organic polyamine provided by the present invention utilizes the synergistic effect of multiple secondary amine and tertiary amine active groups embedded in the bridged-ring skeleton structure to achieve rapid intramolecular proton migration during the chemical absorption process of carbon dioxide, thereby achieving the dual effects of improving the reaction rate and absorption capacity.

[0031] The present invention provides a preparation method of the bridged-ring organic polyamine described in the above technical solution. The preparation method provided by the present invention has few operation steps and a simple production process, and is suitable for large-scale industrial synthesis.

[0032] The present invention provides a bridged-ring organic polyamine absorbent, which comprises the above-mentioned bridged-ring organic polyamine and water. Compared with the traditional alkanolamine absorption method, the present invention conducts targeted design and optimization on the absorbent structure at the molecular level, and has the following excellent properties: through the synergistic effect of multiple secondary amine and tertiary amine active groups embedded in the bridged-ring skeleton structure, the intermolecular proton transfer process in the conventional carbon dioxide chemical absorption process is regulated to occur intramolecularly, thereby greatly improving the reaction rate and absorption capacity. As shown by the test results of the examples, under the conditions of 40 °C and 0.1 MPa, the carbon dioxide absorption capacity of the bridged-ring organic polyamine absorbent provided by the present invention can reach up to 2.05 mol CO2 / mol absorbent within 50 min, and the absorption rate is 0.041 mol CO2 / mol / min. This shows that the absorbent provided by the present invention has a fast absorption rate and a high absorption capacity. Specific Embodiments

[0033] The following combines examples to elaborate in detail on the bridged-ring organic polyamine absorbent provided by the present invention, its preparation method and application, but they cannot be construed as limiting the protection scope of the present invention.

[0034] Example 1

[0035] Synthesis of 2-methyl octahydro-2H-pyrazino[1,2-a]pyrazine I-1

[0036]

[0037] Diethanolamine (100 mmol, 10.51 g), 1-amino-3-methylaminopropan-2-ol (100 mmol, 10.41 g), ethylene glycol dimethyl ether (100 mL) and 2.5 g of Raney nickel were successively added to a 300 mL high-pressure reaction kettle. After sealing, nitrogen was introduced to displace the air, and then hydrogen (5 MPa) was introduced. The high-pressure reaction kettle was reacted at 150 °C for 12 h, and the magnetic stirring speed was 500 r / min. After the reaction was completed, the high-pressure reaction kettle was soaked in an ice-water bath for 0.5 h, and then the reaction solution was filtered, and the filter cake was washed with ethylene glycol dimethyl ether (30 mL × 2). After the washing solution and the filtrate were combined, the solvent ethylene glycol dimethyl ether was removed completely by a rotary evaporator, and 2-methyl octahydro-2H-pyrazino[1,2-a]pyrazine was obtained by vacuum distillation. NMR characterization data: 1 1H NMR (400 MHz, CDCl3) δ = 1.92 - 2.88 (m, 13H), 2.19 (s, 3H), which is consistent with the target product.

[0038] Example 2

[0039] Synthesis of 2-ethyl octahydro-2H-pyrazino[1,2-a]pyrazine I-2

[0040]

[0041] Add diethanolamine (100 mmol, 10.51 g), 1-amino-3-ethylamino-2-propanol (100 mmol, 11.82 g), tetrahydrofuran (100 mL) and 3 g of Raney copper into a 300 mL high-pressure reactor in sequence. After sealing, introduce nitrogen to displace air, and then introduce hydrogen (4 MPa). The high-pressure reactor reacts at 160 °C for 16 h, and the magnetic stirring speed is 500 r / min. After the reaction is completed, soak the high-pressure reactor in an ice-water bath for 0.5 h, then filter the reaction solution, and wash the filter cake with tetrahydrofuran (30 mL × 2). After combining the washing solution and the filtrate, remove the solvent tetrahydrofuran completely using a rotary evaporator, and perform vacuum distillation to obtain 2-ethyl octahydro-2H-pyrazino[1,2-a]pyrazine. NMR characterization data: 1 H NMR (400 MHz, CDCl3) δ = 2.01 - 2.99 (m, 15H), 1.19 (t, 3H), which is consistent with the target product.

[0042] Example 3

[0043] Synthesis of 2-propyl octahydro-2H-pyrazino[1,2-a]pyrazine I-3

[0044]

[0045] Add diethanolamine (100 mmol, 10.51 g), 1-amino-3-propylamino-2-propanol (100 mmol, 13.22 g), dioxane (100 mL) and 3.5 g of Raney copper into a 300 mL high-pressure reactor in sequence. After sealing, introduce nitrogen to displace air, and then introduce hydrogen (6 MPa). The high-pressure reactor reacts at 180 °C for 14 h, and the magnetic stirring speed is 500 r / min. After the reaction is completed, soak the high-pressure reactor in an ice-water bath for 0.5 h, then filter the reaction solution, and wash the filter cake with dioxane (30 mL × 2). After combining the washing solution and the filtrate, remove the solvent dioxane completely using a rotary evaporator, and perform vacuum distillation to obtain 2-propyl octahydro-2H-pyrazino[1,2-a]pyrazine. NMR characterization data: 1 H NMR (400 MHz, CDCl3) δ = 2.05 - 3.02 (m, 15H), 1.35 (m, 2H), 0.88 (t, 3H), which is consistent with the target product.

[0046] Example 4

[0047] Synthesis of 2-isopropyl octahydro-2H-pyrazino[1,2-a]pyrazine I-4

[0048]

[0049] Add diethanolamine (100 mmol, 10.51 g), 1-amino-3-isopropylamino-2-propanol (100 mmol, 13.22 g), methyl tert-butyl ether (100 mL) and 2 g of Raney nickel into a 300 mL high-pressure reactor in sequence. After sealing, nitrogen is introduced to displace the air, and then hydrogen (5 MPa) is introduced. The high-pressure reactor is reacted at 190 °C for 20 h, and the magnetic stirring speed is 500 r / min. After the reaction is completed, the high-pressure reactor is immersed in an ice-water bath for 0.5 h, and then the reaction solution is filtered, and the filter cake is washed with methyl tert-butyl ether (30 mL × 2). After the washing solution and the filtrate are combined, the solvent methyl tert-butyl ether is removed completely by a rotary evaporator, and 2-isopropyl octahydro-2H-pyrazino[1,2-a]pyrazine is obtained by vacuum distillation. NMR characterization data: 1 1H NMR (400 MHz, CDCl3) δ = 2.08 - 3.01 (m, 14H), 1.18 (d, 6H), which is consistent with the target product.

[0050] Example 5

[0051] Synthesis of octahydro-2H-pyrazino[1,2-a]pyrazine I-5

[0052]

[0053] Add diethanolamine (100 mmol, 10.51 g), 1,3-diamino-2-propanol (100 mmol, 9.01 g), dioxane (100 mL) and 1.5 g of Raney nickel into a 300 mL high-pressure reactor in sequence. After sealing, nitrogen is introduced to displace the air, and then hydrogen (3 MPa) is introduced. The high-pressure reactor is reacted at 150 °C for 12 h, and the magnetic stirring speed is 500 r / min. After the reaction is completed, the high-pressure reactor is immersed in an ice-water bath for 0.5 h, and then the reaction solution is filtered, and the filter cake is washed with dioxane (30 mL × 2). After the washing solution and the filtrate are combined, the solvent dioxane is removed completely by a rotary evaporator, and octahydro-2H-pyrazino[1,2-a]pyrazine is obtained by vacuum distillation. NMR characterization data: 1 1H NMR (400 MHz, CDCl3) δ = 2.15 - 3.11 (m, 13H), which is consistent with the target product.

[0054] Example 6

[0055] Synthesis of 2,8-dimethyl octahydro-2H-pyrazino[1,2-a]pyrazine I-6

[0056]

[0057] Diethanolamine (100 mmol, 10.51 g), 1,3-dimethylamino-2-propanol (100 mmol, 11.82 g), dioxane (100 mL) and 5 g of nickel powder were successively added to a 300 mL high-pressure reactor. After sealing, nitrogen was introduced to displace the air, and then hydrogen (4 MPa) was introduced. The high-pressure reactor was reacted at 170 °C for 18 h, and the magnetic stirring speed was 500 r / min. After the reaction was completed, the high-pressure reactor was immersed in an ice-water bath for 0.5 h. Then the reaction solution was filtered, and the filter cake was washed with dioxane (30 mL × 2). After the washing solution and the filtrate were combined, the solvent dioxane was completely removed using a rotary evaporator, and 2,8-dimethyloctahydro-2H-pyrazino[1,2-a]pyrazine was obtained by vacuum distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl3) δ = 2.01 - 2.98 (m, 13H), 2.15 (s, 6H), which is consistent with the target product.

[0058] Example 7

[0059] Synthesis of 2,8-diethyloctahydro-2H-pyrazino[1,2-a]pyrazine I-7

[0060]

[0061] Diethanolamine (100 mmol, 10.51 g), 1,3-diethylamino-2-propanol (100 mmol, 14.62 g), dioxane (100 mL) and 4.5 g of copper powder were successively added to a 300 mL high-pressure reactor. After sealing, nitrogen was introduced to displace the air, and then hydrogen (5 MPa) was introduced. The high-pressure reactor was reacted at 190 °C for 20 h, and the magnetic stirring speed was 500 r / min. After the reaction was completed, the high-pressure reactor was immersed in an ice-water bath for 0.5 h. Then the reaction solution was filtered, and the filter cake was washed with dioxane (30 mL × 2). After the washing solution and the filtrate were combined, the solvent dioxane was completely removed using a rotary evaporator, and 2,8-diethyloctahydro-2H-pyrazino[1,2-a]pyrazine was obtained by vacuum distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl3) δ = 2.03 - 2.97 (m, 17H), 1.10 (t, 6H), which is consistent with the target product.

[0062] Example 8

[0063] Synthesis of 2-ethyl-8-methyloctahydro-2H-pyrazino[1,2-a]pyrazine I-10

[0064]

[0065] Diethanolamine (100 mmol, 10.51 g), 1-ethylamino-3-methylamino-2-propanol (100 mmol, 13.22 g), dioxane (100 mL) and 4 g of skeletal copper were successively added to a 300 mL high-pressure reactor. After sealing, nitrogen was introduced to displace the air, and then hydrogen (6 MPa) was introduced. The high-pressure reactor was reacted at 200 °C for 22 h, and the magnetic stirring speed was 500 r / min. After the reaction was completed, the high-pressure reactor was immersed in an ice-water bath for 0.5 h. Then the reaction solution was filtered, and the filter cake was washed with dioxane (30 mL × 2). After the washing solution and the filtrate were combined, the solvent dioxane was completely removed by a rotary evaporator, and 2-ethyl-8-methyloctahydro-2H-pyrazino[1,2-a]pyrazine was obtained by vacuum distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl3) δ = 2.02 - 2.91 (m, 15H), 2.10 (s, 3H), 1.11 (t, 3H), which is consistent with the target product.

[0066] Example 9

[0067] Synthesis of 2-isopropyl-8-methyloctahydro-2H-pyrazino[1,2-a]pyrazine I-12

[0068]

[0069] Diethanolamine (100 mmol, 10.51 g), 1-isopropylamino-3-methylamino-2-propanol (100 mmol, 14.62 g), dioxane (100 mL) and 4 g of skeletal nickel were successively added to a 300 mL high-pressure reactor. After sealing, nitrogen was introduced to displace the air, and then hydrogen (6 MPa) was introduced. The high-pressure reactor was reacted at 220 °C for 20 h, and the magnetic stirring speed was 500 r / min. After the reaction was completed, the high-pressure reactor was immersed in an ice-water bath for 0.5 h. Then the reaction solution was filtered, and the filter cake was washed with dioxane (30 mL × 2). After the washing solution and the filtrate were combined, the solvent dioxane was completely removed by a rotary evaporator, and 2-isopropyl-8-methyloctahydro-2H-pyrazino[1,2-a]pyrazine was obtained by vacuum distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl3) δ = 2.04 - 3.05 (m, 14H), 2.18 (s, 3H), 1.08 (d, 6H), which is consistent with the target product.

[0070] Example 10

[0071] Synthesis of 2-isopropyl-8-ethyloctahydro-2H-pyrazino[1,2-a]pyrazine I-14

[0072]

[0073] Add diethanolamine (100 mmol, 10.51 g), 1-isopropylamino-3-ethylamino-2-propanol (100 mmol, 16.03 g), dioxane (100 mL) and 5.5 g of Raney nickel into a 300 mL high-pressure reactor in sequence. After sealing, introduce nitrogen to displace air, and then introduce hydrogen (6 MPa). The high-pressure reactor is reacted at 240 °C for 24 h, and the magnetic stirring speed is 500 r / min. After the reaction is completed, soak the high-pressure reactor in an ice-water bath for 0.5 h, then filter the reaction solution, and wash the filter cake with dioxane (30 mL × 2). After combining the washing solution and the filtrate, remove the solvent dioxane completely using a rotary evaporator, and perform vacuum distillation to obtain 2-isopropyl-8-ethyloctahydro-2H-pyrazino[1,2-a]pyrazine. NMR characterization data: 1 1H NMR (400 MHz, CDCl3) δ = 2.02 - 3.08 (m, 16H), 1.14 (t, 3H), 1.07 (d, 6H), which is consistent with the target product.

[0074] Application Example 1

[0075] Add 30 g of the bridged-ring organic polyamine obtained in Examples 1 - 10 and 70 g of deionized water into a 250 mL round-bottom flask. After stirring evenly, slowly introduce a carbon dioxide-nitrogen mixed gas with a carbon dioxide volume content of 15%, the flow rate of the mixed gas is 100 mL / min, the pressure is 0.1 MPa, and the oil bath temperature is 40 °C. Use a gas flowmeter to record the inlet and outlet gas flow rates in real time. The test results of the carbon dioxide absorption performance of the bridged-ring organic polyamine absorbent are shown in Table 1:

[0076] Table 1 Carbon Dioxide Absorption Performance of Bridged-Ring Organic Polyamine Absorbent

[0077]

[0078] As can be seen from Table 1, the bridged-ring organic polyamine absorbent provided by the present invention has excellent carbon dioxide absorption performance.

[0079] Application Example 2

[0080] Under magnetic stirring conditions, place a 250 mL round-bottom flask containing 100 g of the bridged-ring organic polyamine absorbent saturated with carbon dioxide in Application Example 1 in an oil bath, raise the oil bath temperature to 120 °C, and use a gas flowmeter to record the inlet and outlet gas flow rates in real time. The test results of the regeneration performance of the bridged-ring organic polyamine absorbent are shown in Table 2:

[0081] Table 2 Regeneration Performance of Bridged-Ring Organic Polyamine Absorbent

[0082]

[0083] As can be seen from Table 2, the bridged-ring organic polyamine absorbent provided by the present invention has good carbon dioxide desorption performance.

[0084] In view of this, the object of the present invention is to provide a class of bridged-ring organic polyamines as carbon dioxide absorbents and a preparation method for such bridged-ring organic polyamines. The bridged-ring organic polyamine absorbent provided by the present invention has a fast absorption rate, a high absorption capacity, and excellent absorption-desorption recycling performance.

[0085] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

[0086] The numerical values and ranges used in the present invention are clarifying and not restrictive. Although the data and data ranges stated in the specific embodiments of the present invention have been made as accurate as possible in measurement and recording, these data and data ranges inevitably contain certain errors, which are necessarily caused by the standard deviations commonly present in various tests.

Claims

1. A bridged ring organic polyamine, characterized in that: It has the structure shown in formula I: In the formula I, R 1 and R 2 are independently H or C1-C3 alkyl.

2. A bridged ring organic polyamine according to claim 1, characterized in that: It has a structure shown in any one of Formula I-1 to Formula I-15:

3. The method for preparing a bridged ring organic polyamine according to claim 1 or 2, characterized in that: The method comprises the following steps: mixing compound 1, diethanolamine and a transition metal catalyst in an ether organic solvent, then introducing hydrogen gas, and performing a high-temperature and pressure alkylation reaction to obtain the bridged ring organic polyamine; In the compound 1, R 1 and R 2 are independently H or C1-C3 alkyl.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the compound 1 to diethanolamine is 1:(0.2-5).

5. The preparation method according to claim 3, characterized in that: The transition metal catalyst is a copper-based catalyst or a nickel-based catalyst; the added mass of the transition metal catalyst is 0.1-35% of the total mass of the compound 1 and the diethanolamine.

6. The preparation method according to claim 3, characterized in that: The temperature of the high temperature and pressure alkylation reaction is 100-320° C., the time is 1-36 hours, and the hydrogen pressure is 0.1-12 MPa.

7. The preparation method according to claim 3, characterized in that: The ether organic solvent is one or a mixture of two or more of ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, and methyl tert-butyl ether.

8. Use of the bridged ring organic polyamine according to claim 1 or 2 or the bridged ring organic polyamine prepared by the preparation method according to any one of claims 3 to 7, characterized in that: Bridged ring organic polyamines are used as absorbents in absorbing carbon dioxide.

9. The use according to claim 8, characterized in that: The absorbent comprises bridged ring organic polyamine and water. In terms of mass percentage, the mass percentage of the bridged ring organic polyamine accounts for 1-50% and the mass percentage of water accounts for 50-99%.

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