Proton-type ionic liquid super-crosslinked polymer, preparation method thereof and application of proton-type ionic liquid super-crosslinked polymer in carbon dioxide adsorption

Abstract

The invention discloses a proton-type ionic liquid super-crosslinked polymer and a preparation method and application thereof in carbon dioxide adsorption, proton-type ionic liquid is used as a connection building block, and the two types of connection building blocks are subjected to catalytic polymerization by adjusting the ratio of the proton-type ionic liquid to a cross-linking agent connection building block to obtain the proton-type ionic liquid super-crosslinked polymer. The proton type ionic liquid super-crosslinked polymer obtained by the invention has a super-crosslinked anion network structure. The carbon dioxide adsorption and separation capacity is obviously improved by utilizing a high specific surface area, a high total pore volume and exposed multi-nitrogen sites, so that efficient, high-capacity and reversible adsorption of carbon dioxide gas is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of ionic polymer synthesis, and specifically relates to a proton type ionic liquid super cross-linked polymer and a preparation method thereof and an application thereof in adsorbing carbon dioxide. Background Art

[0002] As a greenhouse gas, the rapid increase in the concentration of carbon dioxide in the atmosphere has led to a serious greenhouse effect and many climate changes. At the same time, as an important Cl compound, carbon dioxide can be converted into fuel or other high-value-added chemicals through thermochemistry, photochemistry, and electrochemistry. Therefore, it is of great significance to develop green, economical, efficient and reversible carbon dioxide capture technology.

[0003] At present, the commonly used method for separating and purifying carbon dioxide is mainly organic amine chemical absorption. However, the absorption capacity of the absorbent in this method is low, the desorption energy consumption is high, and the self-degradation produces volatile organic compounds, which is not in line with the principle of sustainable development. Ionic liquids with extremely low volatility, good solubility, high thermal stability and designability provide new ideas for the gas absorption of carbon dioxide. For example, Blanchard et al. measured the solubility of carbon dioxide in different imidazole-type ionic liquids at different pressures, indicating that carbon dioxide can be physically dissolved in ionic liquids, but the solubility is small at normal pressure (Nature 1999, 28); Davis et al. first used amino-functionalized ionic liquids to capture carbon dioxide. Each mole of ionic liquid can capture 0.5 moles of carbon dioxide at normal pressure (J. Am. Chem. Soc., 2002,926), and the mass capture capacity is about 7wt%. Since then, many researchers have developed other amino-containing quaternary phosphonium-type, imidazole-type, quaternary ammonium-type, and pyridine-type ionic liquids for capturing carbon dioxide. However, the high viscosity and low mass transfer of ionic liquids hinder the application of ionic liquids.

[0004] In recent years, solid adsorbents based on ionic liquids (such as polyionic liquids) have attracted people's attention because they not only have the advantages of ionic liquids, but also overcome the shortcomings of the above-mentioned pure ionic liquids. However, conventional polyionic liquids are usually non-porous and the adsorption effect needs to be improved. For example, Mehrdad et al. showed that the carbon dioxide adsorption capacity of polyionic liquids with bromide anions is only 0.7wt%, while the carbon dioxide adsorption capacity of polyionic liquids with thiocyanate anions is only about 2wt% (J. Polym. Res. 2021, 346). Therefore, it is very meaningful to develop new composite adsorbents based on ionic liquids through structural adjustment to improve the carbon dioxide adsorption capacity. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a proton type ionic liquid hyper-crosslinked polymer and its preparation method and application in adsorbing carbon dioxide. The proton type ionic liquid hyper-crosslinked polymer obtained by the present invention has a hyper-crosslinked anion network structure, and utilizes a high specific surface area, a high total pore volume and exposed multiple nitrogen sites to significantly improve the carbon dioxide adsorption and separation capacity, thereby achieving efficient, high-capacity and reversible adsorption of carbon dioxide gas.

[0006] To achieve the above object, the technical solution of the present invention is as follows: A method for preparing a proton-type ionic liquid hyper-crosslinked polymer comprises the following steps: 1) Preparation of ionic liquid: Using the superbase used in the proton-type ionic liquid as the proton acceptor and the azole compound as the proton donor, the proton acceptor and the proton donor are subjected to acid-base neutralization reaction under heating and stirring conditions. After the reaction is completed, the obtained liquid is vacuum dried, and the product collected after drying is the desired proton-type ionic liquid; 2) Hypercrosslinking reaction: Under a nitrogen atmosphere, the proton ionic liquid obtained in step 1) is mixed with a crosslinking agent in an organic solvent, and a Lewis acid is used as a catalyst to react under heating and stirring conditions. After the reaction is completed, the reacted material is cooled to room temperature and then filtered, and the precipitate obtained by filtration is washed until the filtrate is clear and transparent. Finally, the washed precipitate is dried, and the product collected after drying is the proton ionic liquid hypercrosslinked polymer to be prepared.

[0007] Furthermore, 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), and 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), and tetrazole (Tetz).

[0008] Furthermore, in step 1), the molar ratio of the proton acceptor to the proton donor is 1:1; the reaction temperature is 25-60° C.; and the reaction time is 3-24 h.

[0009] Furthermore, 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.

[0010] Furthermore, in step 2), the molar ratio of the proton type ionic liquid to the cross-linking agent is 1:1-7; the molar ratio of the proton type ionic liquid to the Lewis acid is 1:1-50; the reaction temperature is 25-100°C; and the reaction time is 4-24h.

[0011] The invention provides a proton type ionic liquid hyper-crosslinked polymer prepared by the method.

[0012] Furthermore, the typical chemical structure of the polymer is shown in Formula I below:

[0013] The present invention also provides an application of a proton type ionic liquid hyper-crosslinked polymer, and the application is to use the obtained proton type ionic liquid hyper-crosslinked polymer for carbon dioxide adsorption.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The present invention uses a proton-type ionic liquid as a connecting building block, and by adjusting the ratio of the proton-type ionic liquid to the cross-linking agent connecting building block, the two types of connecting building blocks are catalytically polymerized to obtain a type of proton-type ionic liquid hyper-cross-linked polymer. The proton-type ionic liquid hyper-cross-linked polymer prepared by the present invention has a hyper-cross-linked 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; 2) The proton-type ionic liquid hyper-crosslinked polymer prepared by the present invention has a high specific surface area, a high total pore volume and multiple exposed nitrogen sites, which significantly improves the carbon dioxide adsorption and separation capacity, thereby achieving efficient, high-capacity and reversible adsorption of carbon dioxide gas; 3) When the molar ratio of the proton type ionic liquid to the cross-linking agent is 1:5, the proton type ionic liquid hyper-cross-linked polymer has abundant pores and a BET surface area of ​​1800 m 2 g −1 At 100 kPa, the carbon dioxide adsorption and nitrogen adsorption were 3.32 mmol g −1 and 0.0195mmol g −1 , the selectivity of carbon dioxide / nitrogen reaches 170; 4) The proton-type ionic liquid hyper-crosslinked polymer of the present invention has good cyclic absorption stability; 5) The present invention has the advantages of simple preparation process, large specific surface area of ​​the prepared proton-type ionic liquid super-crosslinked polymer, high carbon dioxide capture capacity, etc., and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Infrared spectrum of proton-type ionic liquid hyper-crosslinked polymer ILHCP-1; Figure 2 Scanning electron micrograph of proton-type ionic liquid hypercrosslinked polymer ILHCP-1; Figure 3 Dispersion mapping spectrum of proton-type ionic liquid hypercrosslinked polymer ILHCP-1; Figure 4 X-ray photoelectron spectroscopy of proton-type ionic liquid hypercrosslinked polymer ILHCP-1; Figure 5 Thermogravimetric curve of proton-type ionic liquid hypercrosslinked polymer ILHCP-1; Figure 6 Adsorption curves of carbon dioxide and nitrogen for proton-type ionic liquid hypercrosslinked polymer ILHCP-1 at 273K; Figure 7 Carbon dioxide cyclic adsorption curve of proton-type ionic liquid hyper-crosslinked polymer ILHCP-1 at 273K. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the described scope. Example 1

[0017] 1) Synthesis of ILHCP-1 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and equimolar pyrazole (Pyrz) were mixed and stirred at 60°C without solvent for 3 hours, then the reacted material was cooled to room temperature to form a uniform, transparent and stable liquid, and the obtained liquid was vacuum dried at 60°C for 12 hours to obtain [DBNH][Pyrz] ionic liquid; 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. The reacted material was then cooled to room temperature and filtered. The filtered precipitate 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 hyper-crosslinked polymer ILHCP-1 was obtained.

[0018] 2) Material characterization: Depend on Figure 1 It can be seen that the FT-IR spectrum analysis of the sample shows that at 1150 and 1090 cm −1 The NN stretching vibration of the anion at 1700 and 1250 cm −1 C=N on the cation +and CN bonds; 1450, 1500, and 1600 cm −1 A series of characteristic peaks at 2922 and 2854 cm reflect the stretching vibration of the backbone benzene ring in the proton-type ionic liquid hypercrosslinked polymer. −l The adsorption peak at 1000 nm is attributed to the cross-linking agent methylene bridge (−CH 2 −), and 1266 cm −1 The characteristic peak at can be attributed to the Cl−C vibration caused by the unreacted DCX.

[0019] Depend on Figure 2 The SEM image analysis shows that there are abundant pores in the proton-type ionic liquid hypercrosslinked polymer, and the BET surface area is as high as 1800 m 2 g −1 .

[0020] Depend on Figure 3 From the EDS mapping image analysis, it can be seen that carbon, nitrogen and chlorine elements are evenly dispersed throughout the polymer backbone, indicating that the ionic liquid is evenly dispersed in the network of the proton-type ionic liquid hypercross-linked polymer.

[0021] Depend on Figure 4 Elemental analysis showed that the nitrogen content was 0.44 wt%, and the ionic liquid content was 0.079 mmol g −1 The 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 are located at 400.2, 285.2 and 201.3 eV, respectively.

[0022] Depend on Figure 5 Thermogravimetric analysis showed that at temperatures below 200°C, the mass loss of the sample was less than 5%, indicating that the proton-type ionic liquid hyper-crosslinked polymer had excellent thermal stability. Example 2

[0023] Carbon dioxide and nitrogen adsorption measurement: The absorption device adopts the BET method. The proton-type ionic liquid hypercrosslinked polymer ILHCP-1 synthesized in Example 1 is first subjected to vacuum degassing activation treatment, and then the gas adsorption temperature is controlled to 0°C and the gas pressure is controlled to 0~100kPa. The equilibrium absorption capacity is measured and the data is recorded by a computer.

[0024] The adsorption results of carbon dioxide and nitrogen gases are as follows: Figure 6 As shown in Figure 2, at 100 kPa, the carbon dioxide adsorption and nitrogen adsorption were 3.32 mmol g −1 and 0.0195mmol g −1 , the selectivity of carbon dioxide / nitrogen reaches 170. Example 3

[0025] Carbon dioxide cyclic adsorption measurement: The carbon dioxide adsorption and desorption device adopts the BET method. The proton-type ionic liquid hypercrosslinked polymer ILHCP-1 synthesized in Example 1 is first subjected to vacuum degassing activation treatment, and then the gas adsorption temperature is controlled to be 0°C and the gas pressure is 0-100 kPa. The equilibrium absorption capacity is measured and the data is recorded by a computer. Desorption is carried out at 130°C under reduced pressure for 6 hours to remove the adsorbed carbon dioxide. The absorption-desorption cycle is repeated five times. The results are as follows: Figure 7 As shown, it indicates good cyclic absorption stability.

Claims

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

2. The method for preparing a proton-type ionic liquid hypercrosslinked polymer according to claim 1, characterized in that In step 1), the superbase proton acceptor is one of 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene; the proton donor is one of pyrazole, imidazole, 124-triazole, 123-triazole, and tetrazole.

3. 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 the proton acceptor to the proton donor is 1:1; the reaction temperature is 25-60° C.; and the reaction time is 3-24 h.

4. The method for preparing a proton-type ionic liquid hypercrosslinked polymer according to claim 1, characterized in that In step 2), the crosslinking agent is one of p-dichlorobenzyl, p-dibromobenzyl, benzyl chloride and benzyl bromide; the organic solvent is one of dichloromethane, chloroform and dichloroethane; and the Lewis acid is one of aluminum chloride, ferric chloride and zinc chloride.

5. 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 the proton ionic liquid to the cross-linking agent is 1:1-7; the molar ratio of the proton ionic liquid to the Lewis acid is 1:1-50; the reaction temperature is 25-100°C; and the reaction time is 4-24h.

6. A proton-type ionic liquid hypercrosslinked polymer prepared by the method according to any one of claims 1 to 5.

7. A proton-type ionic liquid hypercrosslinked polymer according to claim 6, characterized in that The typical chemical structure of the polymer is shown in Formula I below:

8. An application of the proton type ionic liquid hypercrosslinked polymer as claimed in claim 6, characterized in that The application is to use the obtained proton type ionic liquid hyper-crosslinked polymer for carbon dioxide adsorption.

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