Hydrophobic ionic liquid-embedded supercrosslinked polymer, preparation method thereof and application of the polymer in selective adsorption of toluene vapor

Abstract

The application discloses a hydrophobic ionic liquid embedded super-crosslinked polymer and a method for preparing and selectively adsorbing toluene vapor, wherein the hydrophobic ionic liquid is used as an embedded compound, the ionic liquid is embedded into the super-crosslinked polymer composed of a crosslinking agent by adjusting the proportion of the connection building blocks of the ionic liquid and the crosslinking agent, and a kind of hydrophobic ionic liquid embedded super-crosslinked polymer is obtained. The hydrophobic ionic liquid embedded super-crosslinked polymer prepared by the application has a super-crosslinked network structure, a large specific surface area, and rich ionic liquid sites, and has high hydrophobicity and can significantly improve the toluene vapor adsorption and separation capacity, so that the efficient, high-capacity and selective reversible adsorption of toluene vapor under high humidity conditions can be realized.

Description

Technical Field

[0001] This invention belongs to the field of hydrophobic polymer synthesis technology, specifically relating to a hydrophobic ionic liquid-embedded hypercrosslinked polymer, its preparation method, and its selective adsorption application for toluene vapor adsorption. Background Technology

[0002] The extensive use of organic solvents in industrial processes has led to a rapid increase in the concentration of volatile organic compounds (VOCs) in the atmosphere. Among these VOCs, aromatic VOCs such as toluene have received more attention due to their high hazard. Catalytic combustion is a common method for eliminating toluene, but it is not only energy-intensive but also generates secondary pollution. Furthermore, aromatic VOCs such as toluene are often accompanied by large amounts of vapor during emission; therefore, it is crucial to develop novel hydrophobic adsorbents for the efficient adsorption of toluene and other compounds under humid conditions.

[0003] Currently, ionic liquids have attracted attention as a novel type of absorbent due to their extremely low volatility (no secondary pollution), good solubility, high thermal stability, and designability. For example, Dai et al. reported that imidazole-based ionic liquids incorporating π-electron donors can achieve effective toluene capture (ACS Sustainable Chem. Eng. 2020, 8(24), 9058-9069), and Wang et al. discussed the effects of cation and anion types and alkyl chain lengths on toluene solubility (Green Energy Environ. 2021, 6(3), 339-349). However, the high viscosity and low mass transfer of ionic liquids hinder their application.

[0004] 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. Ionic liquid-hypercrosslinked polymer adsorbents, prepared by combining ionic liquids with hypercrosslinked polymers prepared by the Friedel-Crafts reaction, have been used to adsorb carbon dioxide gas due to their large specific surface area, porosity, and simple preparation (Chem. Eng. J. 2024, 489 151102). However, there are few reports on their selective adsorption under high humidity conditions for gases such as toluene. Therefore, developing novel composite adsorbents based on ionic liquids through structural adjustment to improve the selective adsorption capacity of toluene under humid conditions is of great significance. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide a hydrophobic ionic liquid-embedded hypercrosslinked polymer, its preparation method, and its application in the selective adsorption of toluene vapor. The hydrophobic ionic liquid-embedded hypercrosslinked polymer obtained by this invention has a hypercrosslinked network structure. Utilizing its high specific surface area, high total pore volume, and exposed ionic liquid sites, it significantly improves the adsorption capacity for selectively adsorbing toluene vapor under humidity conditions, thereby achieving efficient, high-capacity, and reversible selective adsorption of toluene vapor.

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

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

[0008] 1) Preparation of ionic liquids: A non-proton ionic liquid is mixed with a lithium salt containing fluorine compounds and reacted under stirring conditions with an aqueous phase as the solvent. After the reaction is completed, the obtained organic phase liquid is vacuum dried. The product collected after drying is the desired hydrophobic ionic liquid.

[0009] 2) Hypercrosslinking reaction: Under a nitrogen atmosphere, the hydrophobic ionic liquid obtained in step 1) is mixed with the crosslinking agent in an organic solvent. A Lewis acid is used as a catalyst, and the hypercrosslinking 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 hydrophobic ionic liquid-embedded hypercrosslinked polymer to be prepared.

[0010] Further, in step 1), the aprotic ionic liquid is one of tetraphenylphosphonium chloride ([Ph4P][Cl]), tetrabutylphosphonium bromide ([P4444][Br]), tetrabutylammonium bromide ([N4444][Br]), or butylmethylimidazolium bromide ([Bmim][Br]); the lithium salt containing fluorine is one of bis(trifluoromethanesulfonyl)imide lithium salt ([TF2N][Li]), phenyltrifluoromethylacetylacetonate lithium salt ([BTFA][Li]), hexafluoroacetylacetonate lithium salt ([HFA][Li]), thiophenetrifluoromethylacetylacetonate lithium salt ([TTFA][Li]), furantrifluoromethylacetylacetonate lithium salt ([FTFA][Li]), or lithium hexafluorophosphate ([PF6][Li]).

[0011] Furthermore, in step 1), the molar ratio of the aprotic ionic liquid to the lithium salt containing fluorine 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 the hydrophobic ionic liquid to the crosslinking agent is 1:1 to 7; the molar ratio of the hydrophobic ionic liquid to the Lewis acid is 1:1 to 50; the reaction temperature is 25 to 100°C; and the reaction time is 4 to 24 hours.

[0014] This invention proposes a hydrophobic ionic liquid-embedded 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 hydrophobic ionic liquid-embedded hypercrosslinked polymer, wherein the obtained hydrophobic ionic liquid-embedded hypercrosslinked polymer is used for selective adsorption of toluene vapor.

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

[0019] 1) This invention uses a hydrophobic ionic liquid as the embedded body. By adjusting the ratio of the ionic liquid to the crosslinking agent connecting building blocks, the ionic liquid is embedded in a hypercrosslinked polymer composed of a crosslinking agent, thus obtaining a type of hydrophobic ionic liquid-embedded hypercrosslinked polymer. The hydrophobic ionic liquid-embedded hypercrosslinked polymer prepared by this invention has a hypercrosslinked network structure, a large specific surface area, and contains abundant ionic liquid sites. It not only has a high degree of hydrophobicity, but also has a good adsorption capacity for toluene vapor, and can significantly capture toluene vapor under high humidity conditions.

[0020] 2) The hydrophobic ionic liquid-embedded hypercrosslinked polymer prepared in this invention has a high specific surface area, high total pore volume, and exposed ionic liquid sites, which significantly improves the adsorption and separation capacity of toluene vapor, thereby achieving efficient, high-capacity, selective, and reversible adsorption of toluene vapor under high humidity conditions.

[0021] 3) When the molar ratio of the hydrophobic ionic liquid to the crosslinking agent is 5:5, the hydrophobic ionic liquid-embedded hypercrosslinked polymer exhibits abundant pores, resulting in a BET specific surface area of ​​up to m². 2 .g -1 The water contact angle is 110°, and at 80% humidity and a toluene concentration of 2000 ppm, the toluene adsorption capacity is 270 mg / g. -1 ;

[0022] 4) The hydrophobic ionic liquid-encapsulated hypercrosslinked polymer adsorbent 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 of ​​hydrophobic ionic liquid-embedded hypercrosslinked polymer, and high selective adsorption of toluene vapor, and has broad market prospects. Attached Figure Description

[0024] Figure 1 The infrared spectrum of the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP of this invention is shown below.

[0025] Figure 2 This is a scanning electron microscope image of the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP of the present invention;

[0026] Figure 3 The dispersive mapping energy spectrum of the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP of this invention;

[0027] Figure 4 X-ray photoelectron spectroscopy of the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP of this invention;

[0028] Figure 5 Thermogravimetric curve of the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP of this invention;

[0029] Figure 6 This is the solid-state nuclear magnetic resonance spectrum of the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP of the present invention;

[0030] Figure 7 The water contact angle of the hydrophobic ionic liquid-encapsulated hypercrosslinked polymer [Tf2N]-ILHCP of this invention;

[0031] Figure 8 The nitrogen adsorption curve of the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP of this invention is shown at 77K.

[0032] Figure 9 This is the cyclic adsorption curve of toluene vapor at 298K and 80% humidity for the hydrophobic ionic liquid-encapsulated hypercrosslinked polymer [Tf2N]-ILHCP of this invention. Detailed Implementation

[0033] 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

[0034] 1) Synthesis of [Tf2N]-ILHCP

[0035] Tetraphenylphosphonium chloride ([Ph4P][Cl]) was mixed with an equimolar amount of lithium bis(trifluoromethanesulfonylimide) ([TF2N][Li]), and stirred for 3 hours at 60°C with water as the solvent. Then, the reacted material was cooled to room temperature to form a phase-separated, transparent and stable liquid. The obtained organic phase was dried under vacuum at 60°C for 12 hours to obtain the [Ph4P][TF2N] ionic liquid.

[0036] Under a nitrogen atmosphere, a reaction mixture containing [Ph4P][TF2N] (5 mmol), benzyl dichloroethylene (DCX) (5 mmol), dichloroethane (DCE) (70 ml), and ferric chloride (20 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 [Tf2N]-ILHCP hypercrosslinked polymer based on [Ph4P][TF2N] was obtained.

[0037] 2) Material characterization:

[0038] Depend on Figure 1 It can be seen that the FT-IR spectral analysis of the sample shows that the wavelengths at 1498, 1596, and 1674 cm⁻¹ are within the range of 1498, 1596, and 1674 cm⁻¹. -1 A series of characteristic peaks at 925 cm⁻¹ reflect the stretching vibrations of the skeletal benzene ring in the proton-type ionic liquid hypercrosslinked polymer; -1 The adsorption peaks at 1350 and 1134 cm⁻¹ are attributed to the C−H stretching vibrations in the methylene bridge (-CH₂-) of the crosslinking agent in the proton-type ionic liquid hypercrosslinked polymer; -1 The absorption peaks at 1059 and 1197 cm⁻¹ are due to the S=O stretching vibration of the anion; -1 The absorption peaks at that point are due to the stretching vibrations of the -SNS- and -CF3 anions.

[0039] Depend on Figure 2 SEM image analysis revealed that the proton-type ionic liquid hypercrosslinked polymers all have abundant pores.

[0040] Depend on Figure 3 EDS mapping image analysis shows that carbon, phosphorus, nitrogen, oxygen, fluorine and sulfur elements are uniformly dispersed throughout the polymer backbone, indicating that the hydrophobic ionic liquid is uniformly dispersed in the network of the hypercrosslinked polymer.

[0041] Depend on Figure 4X-ray photoelectron spectroscopy analysis revealed that the characteristic peaks of C 1s, O 1s, and F 1s were located at 282.1, 532.1, and 688.1 eV, respectively.

[0042] Depend on Figure 5 Thermogravimetric analysis showed that the sample loss was less than 10% at temperatures below 300°C, indicating that the proton-type ionic liquid hypercrosslinked polymer has excellent thermal stability.

[0043] Depend on Figure 6 Solid-state NMR spectroscopy analysis revealed that the signal peaks at 137 and 129 ppm can be attributed to the substituted and unsubstituted aromatic carbons in the structure, respectively, while the resonance peaks at 36 and 19 ppm are attributed to the carbons in the methylene linker (-CH2-) and the terminal chloromethyl group (-CH2Cl). An asterisk indicates a shoulder peak.

[0044] Depend on Figure 7 Water contact angle analysis showed that the water contact angle of the sample was 110.5°, indicating that the hypercrosslinked polymer embedded in the ionic liquid has excellent hydrophobicity. Example 2

[0045] Nitrogen adsorption measurement: The absorption device adopts the BET method. First, the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP synthesized in Example 1 is subjected to vacuum degassing and activation treatment. Then, the gas adsorption temperature is controlled at 77K and the gas pressure is 0~100kPa. The equilibrium absorption capacity is measured and the data is recorded.

[0046] Nitrogen adsorption results are as follows Figure 8 As shown, the BET specific surface area is 770 m². 2 .g -1 . Example 3

[0047] Cyclic adsorption measurement of 2000 ppm toluene vapor under 80% humidity conditions: The adsorption-desorption apparatus employed a breakthrough method. First, the hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf₂N]-ILHCP synthesized in Example 1 was subjected to vacuum degassing and activation treatment. Then, the gas adsorption temperature was controlled at 298 K, and the breakthrough adsorption capacity was measured. Data was recorded by computer. Desorption was performed at 353 K, indicating difficult desorption, while complete desorption was achieved at 393 K. The cyclic absorption-desorption results are shown in Figure 9, indicating good cyclic absorption stability.

Claims

1. A method for preparing a hydrophobic ionic liquid-embedded hypercrosslinked polymer, characterized in that... Includes the following steps: 1) Preparation of ionic liquids: A non-proton ionic liquid is mixed with a lithium salt containing fluorine compounds and reacted under stirring conditions with an aqueous phase as the solvent. After the reaction is completed, the obtained organic phase liquid is vacuum dried. The product collected after drying is the desired hydrophobic ionic liquid. In step 1), the aprotic ionic liquid is tetraphenylphosphonium chloride; the lithium salt containing fluorine is lithium bis(trifluoromethanesulfonylimide). 2) Hypercrosslinking reaction: Under a nitrogen atmosphere, the hydrophobic ionic liquid obtained in step 1) is mixed with the crosslinking agent in an organic solvent. A Lewis acid is used as a catalyst, and the hypercrosslinking 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 hydrophobic ionic liquid-embedded hypercrosslinked polymer to be prepared. In step 2), the crosslinking agent is either p-dichlorobenzyl or p-dibromobenzyl.

2. The method for preparing a hydrophobic ionic liquid-embedded hypercrosslinked polymer according to claim 1, characterized in that... In step 1), the molar ratio of the aprotic ionic liquid to the lithium salt containing fluorine is 1:1; the reaction temperature is 25~60°C; and the reaction time is 3~24h.

3. The method for preparing a hydrophobic ionic liquid-embedded hypercrosslinked polymer according to claim 1, characterized in that... In step 2), the organic solvent is one of dichloromethane, trichloromethane, or dichloroethane; and the Lewis acid is one of aluminum chloride, ferric chloride, or zinc chloride.

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

5. A hydrophobic ionic liquid-embedded hypercrosslinked polymer prepared by the method according to any one of claims 1-4.

6. The hydrophobic ionic liquid-embedded hypercrosslinked polymer according to claim 5, characterized in that... The chemical structural formula of the polymer is shown in Formula I below: Formula I.

7. An application of the hydrophobic ionic liquid-encapsulated hypercrosslinked polymer as described in claim 5, characterized in that... The application involves using the obtained hydrophobic ionic liquid to encapsulate the hypercrosslinked polymer for selective adsorption of toluene vapor.

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