A protonic ionic liquid super-crosslinked polymer, a preparation method thereof and application of the polymer in adsorbing carbon dioxide

Abstract

The application discloses a kind of proton type ionic liquid supercrosslinked polymer and its preparation method and carbon dioxide adsorption application, with proton type ionic liquid as connecting building block, by adjusting its and the matching of connecting building block of crosslinking agent, two kinds of connecting building block are catalyzed polymerization, obtain a kind of proton type ionic liquid supercrosslinked polymer.The proton type ionic liquid supercrosslinked polymer obtained by the application has supercrosslinked anion network structure.Using high specific surface area, high total pore volume and exposed multiple nitrogen sites, the carbon dioxide adsorption separation capacity is significantly improved, so as to realize the efficient, high capacity, reversible adsorption of carbon dioxide gas.

Description

Technical Field

[0001] This invention belongs to the field of ionic polymer synthesis technology, specifically relating to a proton-type ionic liquid hypercrosslinked polymer, its preparation method, and its application in adsorbing carbon dioxide. Background Technology

[0002] Carbon dioxide, as a greenhouse gas, has led to a rapid increase in atmospheric concentration, resulting in a severe greenhouse effect and various climate changes. At the same time, as an important chloride (Cl) compound, carbon dioxide can be converted into fuels or other high-value-added chemicals through thermochemical, photochemical, and electrochemical processes. Therefore, developing green, economical, efficient, and reversible carbon dioxide capture technologies is of great significance.

[0003] Currently, the most commonly used method for separating and purifying carbon dioxide is the organic amine chemical absorption method. However, this method suffers from low absorption capacity of the absorbent, high desorption energy consumption, and self-degradation producing volatile organic compounds, which does not conform to the principles of sustainable development. Ionic liquids, with their extremely low volatility, good solubility, high thermal stability, and designability, offer a new approach for carbon dioxide gas absorption. For example, Blanchard et al. determined the solubility of carbon dioxide in different imidazole-type ionic liquids at different pressures, showing that carbon dioxide can be dissolved in ionic liquids physically, but the solubility is low at atmospheric pressure (Nature 1999, 28). Davis et al. first used amino-functionalized ionic liquids to capture carbon dioxide, achieving a capture capacity of approximately 7 wt% per mole of ionic liquid at atmospheric pressure (J. Am. Chem. Soc., 2002, 926). Subsequently, many researchers have developed other amino-containing quaternary phosphonium, imidazole, quaternary ammonium, and pyridine ionic liquids for carbon dioxide capture. However, the high viscosity and low mass transfer of ionic liquids hinder their application.

[0004] In recent years, solid adsorbents based on ionic liquids (such as polyionic liquids) have attracted attention because they not only possess the advantages of ionic liquids but also overcome the shortcomings of pure ionic liquids. However, conventional polyionic liquids are usually non-porous, and their adsorption efficiency needs improvement. For example, studies by Mehrdad et al. have shown that the carbon dioxide adsorption capacity of polyionic liquids with bromide anions is only 0.7 wt%, while that of polyionic liquids with thiocyanate anions is only about 2 wt% (J. Polym. Res. 2021, 346). Therefore, it is of great significance to develop novel composite adsorbents based on ionic liquids through structural adjustment to improve carbon dioxide adsorption capacity. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide a proton-type ionic liquid hypercrosslinked polymer, its preparation method, and its application in carbon dioxide adsorption. The proton-type ionic liquid hypercrosslinked polymer obtained by this invention has a hypercrosslinked anionic network structure. Utilizing its high specific surface area, high total pore volume, and exposed multi-nitrogen sites, it significantly improves the carbon dioxide adsorption and separation capacity, thereby achieving efficient, high-capacity, and reversible adsorption of carbon dioxide gas.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing a proton-type ionic liquid hypercrosslinked polymer includes the following steps:

[0008] 1) Preparation of ionic liquids: Using a superbase as a proton acceptor and an azole compound as a proton donor, the proton acceptor and proton donor are subjected to an acid-base neutralization reaction under heating and stirring conditions. After the reaction is completed, the obtained liquid is vacuum dried. The product collected after drying is the desired proton-type ionic liquid.

[0009] 2) Hypercrosslinking reaction: Under a nitrogen atmosphere, the proton-type ionic liquid obtained in step 1) is mixed with the crosslinking agent in an organic solvent. Lewis acid is used as a catalyst, and the reaction is carried out under heating and stirring conditions. After the reaction is completed, the reacted material is cooled to room temperature and then filtered. The precipitate obtained by filtration is washed until the filtrate is clear and transparent. Finally, the washed precipitate is dried. The product collected after drying is the proton-type ionic liquid hypercrosslinked polymer to be prepared.

[0010] Further, in step 1), the superbase proton acceptor is one of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), or 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD); and the proton donor is one of pyrazole (Pyrz), imidazole (Im), 124-triazole (124-Triz), 123-triazole (123-Triz), or tetrazolium (Tetz).

[0011] Furthermore, in step 1), the molar ratio of proton acceptor to proton donor is 1:1; the reaction temperature is 25~60°C; and the reaction time is 3~24h.

[0012] Further, in step 2), the crosslinking agent is one of p-dichlorobenzyl (DCX), p-dibromobenzyl (DBX), benzyl chloride (BC), and benzyl bromide (BB); the organic solvent is one of dichloromethane (DCM), trichloromethane (TCM), and dichloroethane (DCE); and the Lewis acid is one of aluminum chloride, ferric chloride, and zinc dichloride.

[0013] Further, in step 2), the molar ratio of proton-type ionic liquid to crosslinking agent is 1:1~7; the molar ratio of proton-type ionic liquid to Lewis acid is 1:1~50; the reaction temperature is 25~100°C; and the reaction time is 4~24h.

[0014] This invention proposes a proton-type ionic liquid hypercrosslinked polymer prepared using the method described above.

[0015] Furthermore, the typical chemical structural formula of this polymer is shown in Formula I below:

[0016]

[0017] The present invention also proposes an application of a proton-type ionic liquid hypercrosslinked polymer, wherein the obtained proton-type ionic liquid hypercrosslinked polymer is used for carbon dioxide adsorption.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1) This invention uses proton-type ionic liquid as a connecting building block. By adjusting the ratio of proton-type ionic liquid to crosslinking agent connecting building block, the two types of connecting building blocks are catalytically polymerized to obtain a proton-type ionic liquid hypercrosslinked polymer. The proton-type ionic liquid hypercrosslinked polymer prepared by this invention has a hypercrosslinked anionic network structure, a large specific surface area, and contains abundant nitrogen sites. It has a good adsorption capacity for carbon dioxide and can effectively capture carbon dioxide.

[0020] 2) The proton-type ionic liquid hypercrosslinked polymer prepared by this invention has a high specific surface area, high total pore volume and exposed multi-nitrogen sites, which significantly improves the carbon dioxide adsorption and separation capacity, thereby achieving efficient, high-capacity and reversible adsorption of carbon dioxide gas;

[0021] 3) When the molar ratio of proton-type ionic liquid to crosslinking agent is 1:5, the proton-type ionic liquid hypercrosslinked polymer exhibits abundant pores, with a BET surface area reaching 1800 m². 2 g −1 At 100 kPa, the adsorption capacities for carbon dioxide and nitrogen were 3.32 mmol g, respectively. −1 and 0.0195 mmol g −1 The selectivity of carbon dioxide / nitrogen reaches 170;

[0022] 4) The proton-type ionic liquid hypercrosslinked polymer of the present invention exhibits good cyclic absorption stability;

[0023] 5) The present invention has the advantages of simple preparation process, large specific surface area and high carbon dioxide capture capacity of the prepared proton-type ionic liquid hypercrosslinked polymer, and has broad market prospects. Attached Figure Description

[0024] Figure 1 Infrared spectrum of ILHCP-1, a proton-type ionic liquid hypercrosslinked polymer;

[0025] Figure 2 Scanning electron microscope image of ILHCP-1, a proton-type ionic liquid hypercrosslinked polymer;

[0026] Figure 3 Dispersive mapping energy spectrum of ILHCP-1, a proton-type ionic liquid hypercrosslinked polymer;

[0027] Figure 4 X-ray photoelectron spectroscopy of ILHCP-1, a proton-type ionic liquid hypercrosslinked polymer;

[0028] Figure 5 Thermogravimetric curve of ILHCP-1, a proton-type ionic liquid hypercrosslinked polymer;

[0029] Figure 6 Adsorption curves of carbon dioxide and nitrogen in the proton-type ionic liquid hypercrosslinked polymer ILHCP-1 at 273 K;

[0030] Figure 7 Carbon dioxide cycling adsorption curve of ILHCP-1, a proton-type ionic liquid hypercrosslinked polymer, at 273 K. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the scope described. Example 1

[0032] 1) Synthesis of ILHCP-1

[0033] 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) was mixed with an equimolar amount of pyrazole (Pyrz) and stirred at 60°C for 3 hours without solvent. The reactants were then cooled to room temperature to form a homogeneous, transparent and stable liquid. The liquid was then vacuum dried at 60°C for 12 hours to obtain the [DBNH][Pyrz] ionic liquid.

[0034] Under a nitrogen atmosphere, a reaction mixture containing [DBNH][Pyrz] (5 mmol), p-dichlorobenzyl (DCX) (25 mmol), dichloroethane (DCE) (100 ml), and ferric chloride (60 mmol) was stirred at 80°C for 24 hours. After the reaction mixture was cooled to room temperature, it was filtered. The precipitate obtained by filtration was washed with water and ethanol until the filtrate was clear and transparent. Finally, the solid was vacuum dried at 80°C for 24 hours. After drying, the [DBNH][Pyrz]-based hypercrosslinked polymer ILHCP-1 was obtained.

[0035] 2) Material characterization:

[0036] Depend on Figure 1 It can be seen that the FT-IR spectral analysis of the sample shows that the wavelengths at 1150 and 1090 cm⁻¹ are... −1 The NN stretching vibration on the anion at 1700 and 1250 cm⁻¹ −1 C=N at the cation + and CN bond; 1450, 1500 and 1600 cm −1 A series of characteristic peaks at 2922 and 2854 cm⁻¹ reflect the stretching vibrations of the skeletal benzene ring in the proton-type ionic liquid hypercrosslinked polymer; in addition, the peaks at 2922 and 2854 cm⁻¹... −l The adsorption peak at 1266 cm⁻¹ is attributed to the C-H stretching vibration in the methylene bridge (−CH₂−) of the crosslinking agent in the proton-type ionic liquid hypercrosslinked polymer, while the peak at 1266 cm⁻¹ is attributed to the C−H stretching vibration in the methylene bridge (−CH₂−) of the crosslinking agent. −1 The characteristic peak at that location can be attributed to the Cl−C vibration caused by unreacted DCX.

[0037] Depend on Figure 2 SEM image analysis revealed that the proton-type ionic liquid hypercrosslinked polymers all possess abundant pores, with a BET surface area reaching 1800 m². 2 g −1 .

[0038] Depend on Figure 3 EDS mapping image analysis shows that carbon, nitrogen, and chlorine elements are uniformly dispersed throughout the polymer backbone, indicating that the ionic liquid is uniformly dispersed in the network of the proton-type ionic liquid hypercrosslinked polymer.

[0039] Depend on Figure 4 Elemental analysis revealed that nitrogen content was 0.44 wt%, resulting in an ionic liquid content of 0.079 mmol / g. −1 X-ray photoelectron spectroscopy analysis of the proton-type ionic liquid hypercrosslinked polymer revealed that the characteristic peaks of N 1s, C 1s, and Cl 2p were located at 400.2, 285.2, and 201.3 eV, respectively.

[0040] Depend on Figure 5Thermogravimetric analysis showed that the mass loss of the sample was less than 5% at temperatures below 200°C, indicating that the proton-type ionic liquid hypercrosslinked polymer has excellent thermal stability. Example 2

[0041] Carbon dioxide and nitrogen adsorption measurement: The absorption device adopts the BET method. First, the proton-type ionic liquid hypercrosslinked polymer ILHCP-1 synthesized in Example 1 is subjected to vacuum degassing activation treatment. Then, the gas adsorption temperature is controlled at 0°C and the gas pressure is 0~100kPa. The equilibrium absorption capacity is measured and the data is recorded by computer.

[0042] The adsorption results of carbon dioxide and nitrogen gases are as follows: Figure 6 As shown, at 100 kPa, the adsorption capacities of carbon dioxide and nitrogen were 3.32 mmol g, respectively. −1 and 0.0195 mmol g −1 The selectivity for carbon dioxide / nitrogen reaches 170. Example 3

[0043] Carbon dioxide cyclic adsorption measurement: The carbon dioxide adsorption-desorption device adopted the BET method. First, the proton-type ionic liquid hypercrosslinked polymer ILHCP-1 synthesized in Example 1 was subjected to vacuum degassing activation treatment. Then, the gas adsorption temperature was controlled at 0℃ and the gas pressure at 0~100kPa. The equilibrium absorption capacity was measured, and the data was recorded by computer. Desorption was performed at 130℃ under reduced pressure for 6 hours to remove the adsorbed carbon dioxide. The adsorption-desorption cycle was repeated five times, and the results are as follows: Figure 7 As shown, this indicates good stability during cyclic absorption.

Claims

1. A method for preparing a proton-type ionic liquid hypercrosslinked polymer, characterized in that... Includes the following steps: 1) Preparation of ionic liquids: Using a superbase as a proton acceptor and an azole compound as a proton donor, the proton acceptor and proton donor are subjected to an acid-base neutralization reaction under heating and stirring conditions. After the reaction is completed, the obtained liquid is vacuum dried. The product collected after drying is the desired proton-type ionic liquid. 2) Hypercrosslinking reaction: Under a nitrogen atmosphere, the proton-type ionic liquid obtained in step 1) is mixed with the crosslinking agent in an organic solvent. Lewis acid is used as a catalyst, and the reaction is carried out under heating and stirring conditions. After the reaction is completed, the reacted material is cooled to room temperature and then filtered. The precipitate obtained by filtration is washed until the filtrate is clear and transparent. Finally, the washed precipitate is dried. The product collected after drying is the proton-type ionic liquid hypercrosslinked polymer to be prepared. In step 1), the superbase proton acceptor is 1,5-diazabicyclo[4.3.0]non-5-ene; the proton donor is pyrazole; In step 2), the crosslinking agent is p-dichlorobenzyl; the organic solvent is dichloroethane; and the Lewis acid is ferric chloride.

2. The method for preparing a proton-type ionic liquid hypercrosslinked polymer according to claim 1, characterized in that... In step 1), the molar ratio of proton acceptor to proton donor is 1:1; the reaction temperature is 25~60°C; and the reaction time is 3~24h.

3. The method for preparing a proton-type ionic liquid hypercrosslinked polymer according to claim 1, characterized in that... In step 2), the molar ratio of proton-type ionic liquid to crosslinking agent is 1:1~7; the molar ratio of proton-type ionic liquid to Lewis acid is 1:1~50; the reaction temperature is 25~100°C; and the reaction time is 4~24h.

4. A proton-type ionic liquid hypercrosslinked polymer prepared by the method according to any one of claims 1-3.

5. An application of the proton-type ionic liquid hypercrosslinked polymer as described in claim 4, characterized in that... The application is to use the obtained proton-type ionic liquid hypercrosslinked polymer for carbon dioxide adsorption.

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