Polyamine heterocyclic compound, preparation method and application thereof, and polyamine heterocyclic compound combined solution

Abstract

The invention provides a polyamido heterocyclic compound, a preparation method and application thereof, and a polyamido heterocyclic compound combined solution, and relates to the technical field of carbon dioxide capture. According to the polyamine heterocyclic compound provided by the invention, the advantage that the structure of a nitrogen-containing heterocyclic ring is easy to modify is utilized, and an aminopropyl side chain is introduced to realize a polyamine synergistic effect, that is, intramolecular proton migration is promoted in a thermodynamically favorable six-membered ring transition state form in a carbon dioxide absorption process, so that the absorption reaction rate and the amine utilization rate are improved. An alkyl substituent R in the amino propyl side chain structure is also beneficial to formation of a transition state of the six-membered ring. The invention provides a polyamido heterocyclic compound combined solution which 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 in particular to a polyamine-based heterocyclic compound, a preparation method and application thereof, and a polyamine-based heterocyclic compound combined solution. Background Art

[0002] Carbon dioxide is the primary greenhouse gas. Excessive emissions of industrial waste gas will lead to a sharp increase in atmospheric carbon dioxide concentration, causing climate change represented by global warming. Carbon capture, utilization and storage technology (CCUS) is currently the most effective countermeasure to excessive industrial carbon dioxide emissions, and is also an important means to achieve my country's "carbon reduction" and "carbon neutrality" goals. The fast, high-capacity, low-energy consumption, and low-loss carbon capture process constitutes the material basis of CCUS technology, and is also the fundamental premise for determining the development and implementation of CCUS technology.

[0003] The chemical absorption of carbon dioxide by ethanolamine solution (reaction formula 1) is currently the most mature and widely used carbon capture strategy in the industry. It has the advantages of fast response, high carbon dioxide selectivity, simple equipment and low cost of amine solution. Related enterprises at home and abroad have already built a number of demonstration devices. However, due to the limitations of the structure of ethanolamine absorbents themselves, there are only two carbon atoms between the hydroxyl group and the amine group in the molecule, resulting in a greater influence of the electron-pulling induction effect of the hydroxyl group on the alkalinity of the amine group, which weakens the reactivity of ethanolamine in the process of chemical absorption of carbon dioxide. In addition, the amine content of ethanolamine compounds is also low, and most molecules contain only one active amine group, which also limits their carbon dioxide cycle capture capacity in actual production.

[0004] Reaction 1:

[0005]

[0006] The above-mentioned essential shortcomings at the molecular level have become a bottleneck that is difficult to overcome in the further optimization and development of alcoholamine carbon dioxide chemical absorbers. Therefore, the academic and industrial circles are in urgent need of designing and developing the next generation of new chemical absorption systems with higher reaction activity and capture capacity, so as to solve the shortcomings of alcoholamine molecules in reaction driving force from the source. Summary of the invention

[0007] The purpose of the present invention is to provide a polyamine heterocyclic compound and a preparation method and application thereof, and a polyamine heterocyclic compound combined solution. The polyamine heterocyclic compound combined solution 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 object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a polyamine heterocyclic compound having a structure shown in Formula I:

[0010]

[0011] In the formula I, X is CH 2 , O or NH; R is a C1-C4 alkyl group, preferably a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group or a tert-butyl group.

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

[0013]

[0014] The present invention provides a method for preparing the polyamine heterocyclic compound described in the above scheme, comprising the following steps:

[0015] The metal catalyst, compound 1 and compound 2 are mixed in an ether solvent, and then hydrogen is introduced to perform a pressurized high-temperature alkylation reaction to obtain the polyamine heterocyclic compound;

[0016]

[0017] In the compound 1, X is CH 2 , O or NH;

[0018] In the compound 2, R is a C1-C4 alkyl group.

[0019] Furthermore, the present invention preferably dissolves compound 2 in an ether solvent first, then adds compound 1, the ether solvent in which compound 2 is dissolved, and a metal catalyst into a high-pressure reactor, seals the reactor, purges the air in the reactor with nitrogen, and after the purging is completed, introduces hydrogen to carry out a pressurized high-temperature alkylation reaction.

[0020] Furthermore, in the present invention, the pressurized high temperature alkylation reaction is preferably carried out under stirring conditions. The present invention has no special requirements for the stirring rate, which is specifically 500 r / min in the embodiment of the present invention.

[0021] Furthermore, after completing the pressurized high-temperature alkylation reaction, the present invention preferably cools the obtained reaction liquid and then filters it, washes the filter cake with an ether solvent, combines the washing liquid and the filtrate, removes the solvent with a rotary evaporator, and distills the polyamino heterocyclic compound under reduced pressure.

[0022] Furthermore, the molar ratio of compound 1 to compound 2 is 1:(1-1000), preferably 1:(1-100), and more preferably 1:(1-25).

[0023] Furthermore, the metal catalyst is a nickel-based catalyst or a copper-based catalyst, the nickel-based catalyst is preferably skeleton nickel, nickel oxide or nickel powder; the copper-based catalyst is preferably skeleton copper, cupric oxide, cuprous oxide or copper powder; the mass of the metal catalyst is 0.01 to 35% of the total mass of compound 1 and compound 2, preferably 1 to 20%, and more preferably 2 to 15%.

[0024] Furthermore, the ether solvent is one or more of dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether. The present invention has no special requirements on the amount of the ether solvent, as long as it can dissolve the raw materials.

[0025] Furthermore, the temperature of the pressurized high temperature alkylation reaction is 80 to 350° C., preferably 120 to 280° C., and more preferably 150 to 210° C.; the time of the pressurized high temperature alkylation reaction is 1 to 48 hours, preferably 5 to 36 hours, and more preferably 10 to 18 hours; the hydrogen pressure is 0.1 to 15 MPa, and preferably 1 to 6 MPa.

[0026] The present invention provides the use of the polyamine heterocyclic compound described in the above scheme or the polyamine heterocyclic compound prepared by the preparation method described in the above scheme in absorbing carbon dioxide.

[0027] Furthermore, when the polyamine heterocyclic compound combined solution of the present invention is used to absorb carbon dioxide, the carbon dioxide volume concentration is preferably 1-95%, the mixed gas flow pressure is preferably 0.1-3 MPa; the absorption temperature is preferably 15-75°C, and the combined solution regeneration temperature is preferably 80-160°C.

[0028] Furthermore, the present invention has no special requirements on the source of the carbon dioxide, and any source known in the art can be used, such as power plant flue gas, refinery tail gas, steel plant tail gas, cement plant tail gas, petrochemical plant tail gas, water gas, biogas, natural gas or carbonate ore decomposition gas. The present invention can achieve the purpose of capturing carbon dioxide or removing carbon dioxide from a mixed gas stream containing carbon dioxide by absorbing carbon dioxide.

[0029] The present invention provides a polyamine heterocyclic compound combined solution, which comprises, by weight percentage, 1-99% (specifically 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, which are not exhaustively listed here) of the polyamine heterocyclic compound described in the above scheme or the polyamine heterocyclic compound prepared by the preparation method described in the above scheme, 1-98% of solvent and 0-98% of auxiliary agent. In an embodiment of the present invention, the polyamine heterocyclic compound combined solution is composed of 30wt% of polyamine heterocyclic compound, 5wt% of auxiliary agent and 65wt% of solvent; in the embodiment, the auxiliary agent is piperazine and the solvent is water.

[0030] Furthermore, the present invention has no special requirements for the preparation method of the polyamine-heterocyclic compound combination solution, and the components can be directly mixed evenly.

[0031] Furthermore, the auxiliary agent includes one or more of an activator, an antioxidant, an anticorrosive agent and a defoamer; the present invention does not make special requirements on the ratio of each auxiliary agent. In the present invention, the activator is preferably ethanolamine, N-methylethanolamine, N 1 ,N 2 -dimethylethylenediamine, 2-hydroxyethylethylenediamine, piperazine, 1,3-diamino-2-hydroxypropane, 2,2-dimethyl-1,3-propylenediamine, 2-methylpiperazine, 4-methylpiperazine, 2,4-dimethylpiperazine, 2-aminoethylpiperazine, 2-aminopropylpiperazine, 2-aminopropylmorpholine, 2-aminopropylpiperidine, diethylenetriamine, triethylenetetramine, or two or more thereof; the antioxidant is preferably acetaldehyde oxime, acetone oxime, butanone oxime, pyrogallol, carbohydrazide, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), N 1 ,N 2 -bis(salicylidene)-1,2-propylenediamine; the corrosion inhibitor is preferably sodium oxalate and / or sodium malonate; the defoaming agent is preferably one or more of sodium benzoate, sodium phenylacetate, sodium phenylpropionate, sodium acetate, sodium propionate, sodium glycinate, sodium alanine, sodium bicarbonate, sodium carbonate, potassium bicarbonate and potassium carbonate.

[0032] Furthermore, the solvent is water, an organic solvent or a mixture of an organic solvent and water, and the organic solvent is preferably one or more of methanol, ethanol, propanol, methoxyethanol, ethylene glycol, diethylene glycol, triethylene glycol, diethylene glycol methyl ether, triethylene glycol methyl ether, diethanol dimethyl ether, triethylene glycol dimethyl ether, cyclopentane, N-methylpyrrolidone, and dimethyl sulfoxide.

[0033] The polyamine heterocyclic compound provided by the present invention takes advantage of the ease of structural modification of nitrogen-containing heterocyclic rings and achieves a polyamine synergistic effect by introducing an aminopropyl side chain, that is, in the process of absorbing carbon dioxide, it promotes intramolecular proton migration in the form of a thermodynamically favorable six-membered ring transition state (as shown in the following formula), thereby improving the absorption reaction rate and the utilization rate of the amino group. The alkyl substituent R in the aminopropyl side chain structure is also conducive to the formation of the six-membered ring transition state.

[0034]

[0035] The present invention provides a method for preparing the polyamine heterocyclic compound described in the above technical scheme. The preparation method provided by the present invention adopts commercialized reaction raw materials, has fewer operation steps, and a simple production process, and is suitable for industrial large-scale synthesis.

[0036] The present invention provides a polyamine heterocyclic compound solution, comprising the above-mentioned polyamine heterocyclic compound, a solvent and one or more of the following auxiliary components: an activator, an antioxidant, an anticorrosive agent and a defoaming agent. Compared with the traditional alcohol amine absorption method, the present invention carries out targeted design and optimization of the absorbent structure at the molecular level, and has the following excellent performance: the polyamine synergistic effect is achieved by introducing an aminopropyl side chain, that is, in the process of absorbing carbon dioxide, the intramolecular proton migration is promoted in the form of a thermodynamically favorable six-membered ring transition state, thereby improving the absorption reaction rate and the utilization rate of the amine group. The alkyl substituent R in the aminopropyl side chain structure is also conducive to the formation of the six-membered ring transition state. As shown in the test results of the embodiment, the carbon dioxide absorption rate of the combined solution provided by the present invention can reach up to 0.58wt% / min and the absorption capacity can reach up to 17.3wt% within 30min under the conditions of 40°C and 0.1MPa. It shows that the combined solution provided by the present invention has a fast absorption rate and a high absorption capacity. DETAILED DESCRIPTION

[0037] The polyamine-based heterocyclic compound and its preparation method and application, and the polyamine-based heterocyclic compound combined solution provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0038] Example 1

[0039] Synthesis of N-methyl-3-piperidinyl-1-propylamine I-1

[0040]

[0041] 3-Piperidinylpropanol (100mmol, 14.32g), dioxane solution of methylamine (300mL, 0.5mol / L) and skeleton nickel (2.5g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (3MPa) was introduced. The autoclave was reacted at 150°C for 48h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-methyl-3-piperidinyl-1-propylamine was obtained by reduced pressure distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl 3 )δ=1.29-1.61(m,8H),2.31-2.77(m,11H), consistent with the target product.

[0042] Example 2

[0043] Synthesis of N-propyl-3-piperidinyl-1-propylamine I-3

[0044]

[0045] 3-Piperidinylpropanol (100mmol, 14.32g), dioxane solution of propylamine (500mL, 0.5mol / L) and skeleton copper (3g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (4MPa) was introduced. The autoclave was reacted at 200°C for 18h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-propyl-3-piperidinyl-1-propylamine was obtained by vacuum distillation. NMR characterization data: 1 HNMR (400MHz, CDCl 3 )δ=1.11-1.59(m,13H),2.42-2.81(m,10H), consistent with the target product.

[0046] Example 3

[0047] Synthesis of N-methyl-3-morpholinyl-1-propylamine I-6

[0048]

[0049] 3-Morpholinopropanol (100mmol, 14.52g), dioxane solution of methylamine (200mL, 0.5mol / L) and nickel powder (5g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (1.5MPa) was introduced. The autoclave was reacted at 190°C for 15h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice-water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-methyl-3-morpholino-1-propylamine was obtained by reduced pressure distillation. NMR characterization data: 1 HNMR (400MHz, CDCl 3 )δ=1.55-1.59(m,2H),2.37-2.77(m,11H),3.64-3.70(m,4H), consistent with the target product.

[0050] Example 4

[0051] Synthesis of N-ethyl-3-morpholinyl-1-propylamine I-7

[0052]

[0053] 3-Morpholinopropanol (100mmol, 14.52g), dioxane solution of ethylamine (400mL, 0.5mol / L) and nickel oxide (3.5g) were added to a 1L autoclave in sequence, sealed, and nitrogen was introduced to replace the air, and finally hydrogen (2MPa) was introduced. The autoclave was reacted at 160°C for 30h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice-water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-ethyl-3-morpholino-1-propylamine was obtained by reduced pressure distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl 3 )δ=1.51-1.62(m,5H),2.35-2.71(m,10H),3.65-3.71(m,4H), consistent with the target product.

[0054] Example 5

[0055] Synthesis of N-propyl-3-morpholinyl-1-propylamine I-8

[0056]

[0057] 3-Morpholinopropanol (100mmol, 14.52g), dioxane solution of propylamine (500mL, 0.5mol / L) and skeleton nickel (4g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (4.5MPa) was introduced. The autoclave was reacted at 210°C for 8h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-propyl-3-morpholino-1-propylamine was obtained by vacuum distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl 3 )δ=1.20-1.58(m,7H),2.34-2.72(m,10H),3.64-3.71(m,4H), consistent with the target product.

[0058] Example 6

[0059] Synthesis of N-isopropyl-3-morpholinyl-1-propylamine I-9

[0060]

[0061] 3-Morpholinopropanol (100mmol, 14.52g), dioxane solution of isopropylamine (600mL, 0.5mol / L) and skeleton nickel (4.5g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (6MPa) was introduced. The autoclave was reacted at 240°C for 32h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-isopropyl-3-morpholino-1-propylamine was obtained by vacuum distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl 3 )δ=1.21-1.66(m,8H),2.32-2.71(m,9H),3.61-3.73(m,4H), consistent with the target product.

[0062] Example 7

[0063] Synthesis of N-methyl-3-piperazinyl-1-propylamine I-11

[0064]

[0065] 3-Piperazine propanol (100mmol, 14.42g), dioxane solution of methylamine (400mL, 0.5mol / L) and cuprous oxide (5g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (5MPa) was introduced. The autoclave was reacted at 220°C for 28h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-methyl-3-piperazine-1-propylamine was obtained by reduced pressure distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl 3 )δ=1.54-1.58(m,2H),2.28-2.81(m,15H), consistent with the target product.

[0066] Example 8

[0067] Synthesis of N-ethyl-3-piperazinyl-1-propylamine I-12

[0068]

[0069] 3-Piperazine propanol (100mmol, 14.42g), dioxane solution of ethylamine (300mL, 0.5mol / L) and skeleton nickel (2.5g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (3MPa) was introduced. The autoclave was reacted at 200°C for 16h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-ethyl-3-piperazinyl-1-propylamine was obtained by reduced pressure distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl 3 )δ=1.52-1.65(m,5H),2.29-2.80(m,14H), consistent with the target product.

[0070] Example 9

[0071] Synthesis of N-propyl-3-piperazinyl-1-propylamine I-13

[0072]

[0073] 3-Piperazine propanol (100mmol, 14.42g), dioxane solution of propylamine (500mL, 0.5mol / L) and skeleton nickel (3.5g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (5.5MPa) was introduced. The autoclave was reacted at 230°C for 18h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-propyl-3-piperazinyl-1-propylamine was obtained by reduced pressure distillation. NMR characterization data: 1 H NMR (400 MHz, CDCl 3 )δ=1.22-1.61(m,7H),2.25-2.74(m,14H), consistent with the target product.

[0074] Example 10

[0075] Synthesis of N-butyl-3-piperazinyl-1-propylamine I-15

[0076]

[0077] 3-Piperazine propanol (100mmol, 14.42g), dioxane solution of butylamine (600mL, 0.5mol / L) and copper powder (4.5g) were added to a 1L autoclave in sequence, and nitrogen was introduced to replace the air after sealing, and finally hydrogen (6MPa) was introduced. The autoclave was reacted at 260°C for 26h, and the magnetic stirring speed was 500r / min. After the reaction was completed, the autoclave was soaked in an ice water bath for 0.5h, and then the reaction solution was filtered, and the filter cake was washed with dioxane (30mL×2). After the washing liquid and the filtrate were combined, the solvent dioxane was removed by rotary evaporator, and N-butyl-3-piperazine-1-propylamine was obtained by vacuum distillation. NMR characterization data: 1 HNMR (400MHz, CDCl 3 )δ=1.11-1.55(m,9H),2.26-2.78(m,14H), consistent with the target product.

[0078] Application Examples 1 to 10

[0079] In a 250 mL round-bottom flask, 30 g of the polyamine heterocyclic compound obtained in Examples 1 to 10, 5 g of piperazine, and 65 g of deionized water were added. After stirring, a carbon dioxide-nitrogen mixed gas with a carbon dioxide volume content of 15% was slowly introduced. The mixed gas flow rate was 100 mL / min, the pressure was 0.1 MPa, and the oil bath temperature was 40° C. The inlet and outlet gas flow rates were recorded in real time with a gas flow meter. The test results of the absorption performance of the polyamine heterocyclic compound combined solution for carbon dioxide are shown in Table 1:

[0080] Table 1 Carbon dioxide absorption performance of polyamine heterocyclic compound combination solution

[0081]

[0082]

[0083] It can be seen from Table 1 that the polyamine-heterocyclic compound combination solution provided by the present invention has an excellent absorption effect on carbon dioxide.

[0084] Application Examples 11 to 20

[0085] Under magnetic stirring conditions, a 250 mL round-bottom flask containing 100 g of the polyamine-based heterocyclic compound combination solution saturated with carbon dioxide absorption in Application Example 1 was placed in an oil bath, the oil bath temperature was raised to 120° C., and the inlet and outlet gas flow rates were recorded in real time with a gas flow meter. The regeneration performance test results of the polyamine-based heterocyclic compound combination solution are shown in Table 2:

[0086] Table 2 Regeneration performance of polyamine heterocyclic compound combination solution

[0087]

[0088]

[0089] It can be seen from Table 2 that the polyamine-heterocyclic compound combination solution provided by the present invention has a good desorption effect on carbon dioxide and has the ability to be recycled.

[0090] In view of this, the object of the present invention is to provide a polyamine heterocyclic compound combination solution as a carbon dioxide absorbent, and a preparation method of the polyamine heterocyclic compound. The polyamine heterocyclic compound combination solution provided by the present invention has a fast absorption rate, a high absorption capacity, and excellent recycling performance.

[0091] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0092] The numerical values ​​and numerical ranges used in the present invention are for clarification rather than limitation. Although the data and numerical ranges stated in the specific embodiments of the present invention have been measured and recorded as accurately as possible, these data and numerical ranges inevitably contain certain errors, which are inevitably generated by the standard deviations that are prevalent in various tests.

Claims

1. A polyamine heterocyclic compound, characterized in that: It has the structure shown in formula I: In the formula I, X is CH2, O or NH, and R is a C1-C4 alkyl group.

2. The polyamine heterocyclic compound 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 polyamine heterocyclic compound according to claim 1 or 2, characterized in that: The following steps are involved: The metal catalyst, compound 1 and compound 2 are mixed in an ether solvent, and then hydrogen is introduced to perform a pressurized high-temperature alkylation reaction to obtain the polyamine heterocyclic compound; In the compound 1, X is CH2, O or NH; In the compound 2, R is a C1-C4 alkyl group.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the compound 1 to the compound 2 is 1:(1-1000).

5. The preparation method according to claim 3, characterized in that: The metal catalyst is a nickel-based catalyst or a copper-based catalyst; the added mass of the metal catalyst is 0.01-35% of the total mass of compound 1 and compound 2.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The temperature of the pressurized high-temperature alkylation reaction is 80-350° C., the time is 1-48 hours, and the hydrogen pressure is 0.1-15 MPa.

7. Use of the polyamine heterocyclic compound according to claim 1 or 2 or the polyamine heterocyclic compound prepared by the preparation method according to any one of claims 3 to 6 in absorbing carbon dioxide.

8. A polyamine heterocyclic compound combined solution, characterized in that: Calculated by mass percentage, the invention comprises 1 to 99% of the polyamine heterocyclic compound according to claim 1 or 2 or the polyamine heterocyclic compound prepared by the preparation method according to any one of claims 3 to 6, 1 to 98% of a solvent and 0 to 98% of an auxiliary agent.

9. The polyamine-heterocyclic compound combined solution according to claim 8, characterized in that: The auxiliary agent is one or more than two of an activator, an antioxidant, an anticorrosive agent and a defoaming agent.

10. The polyamine-heterocyclic compound combined solution according to claim 8, characterized in that: The solvent is water, an organic solvent or a mixture of an organic solvent and water.

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