Hydrophobic ionic liquid embedded super-crosslinked polymer, preparation method thereof and application of hydrophobic ionic liquid embedded super-crosslinked polymer in selective adsorption of toluene steam

Abstract

The invention discloses a hydrophobic ionic liquid embedded super-cross-linked polymer and a preparation method thereof and a method for selectively adsorbing toluene vapor, the hydrophobic ionic liquid is used as an embedded compound, and the ionic liquid is embedded in the super-cross-linked polymer formed by a cross-linking agent by adjusting the ratio of the hydrophobic ionic liquid to a cross-linking agent connecting building block, so that the hydrophobic ionic liquid embedded super-cross-linked polymer is obtained. The hydrophobic ionic liquid embedded super-cross-linked polymer prepared by the method has a super-cross-linked network structure, a large specific surface area and rich ionic liquid sites, not only has higher hydrophobicity, but also can obviously improve the toluene steam adsorption separation capacity, and can be used for preparing the hydrophobic ionic liquid embedded super-cross-linked polymer. Therefore, high-efficiency, high-capacity and selective reversible adsorption of toluene steam under a high-humidity condition is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrophobic polymer synthesis, and in particular relates to a hydrophobic ionic liquid embedded hyper-crosslinked polymer, a preparation method thereof, and selective adsorption application of toluene vapor. Background Art

[0002] The extensive use of organic solvents in industrial processes has caused 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 higher harmfulness. Catalytic combustion is commonly used to eliminate toluene, but it is not only energy-intensive, but also produces secondary pollution. In addition, aromatic VOCs such as toluene are often accompanied by a large amount of steam when they are discharged, so it is very important to develop new hydrophobic adsorbents to efficiently adsorb compounds such as toluene under humid conditions.

[0003] At present, ionic liquids as a new type of absorbent have attracted attention due to their extremely low volatility, no secondary pollution, good solubility, high thermal stability and designability. For example, Dai et al. reported that the introduction of π-electron donor imidazolyl ionic liquids 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 length on toluene solubility (Green Energy Environ. 2021, 6(3), 339-349). However, the high viscosity and low mass transfer of ionic liquids hinder the application of ionic liquids.

[0004] Solid adsorbents based on ionic liquids (such as polyionic liquids) not only have the advantages of ionic liquids, but also overcome the shortcomings of the above-mentioned pure ionic liquids, and have attracted people's attention. However, conventional polyionic liquids are usually non-porous, and the adsorption effect needs to be improved. Ionic liquid hyper-crosslinked polymer adsorbents prepared by combining ionic liquids with hyper-crosslinked polymers prepared by 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 the selective adsorption of gases such as toluene under high humidity conditions. Therefore, it is very meaningful to develop new composite adsorbents based on ionic liquids through structural adjustment to improve the selective adsorption capacity of toluene for toluene adsorption under humid conditions. Summary of the invention

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

[0006] To achieve the above object, the technical solution of the present invention is as follows: A method for preparing a hydrophobic ionic liquid-embedded hyper-crosslinked polymer comprises the following steps: 1) Preparation of ionic liquid: a non-protonic ionic liquid is mixed with a lithium salt of a fluorine-containing compound, and the reaction is carried out in an aqueous phase as a solvent under stirring conditions. After the reaction is completed, the obtained organic phase liquid is vacuum dried, and the product collected after drying is the desired hydrophobic ionic liquid; 2) Hypercrosslinking reaction: Under a nitrogen atmosphere, the hydrophobic 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 carry out a hypercrosslinking reaction 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 hydrophobic ionic liquid-embedded hypercrosslinked polymer to be prepared.

[0007] Furthermore, in step 1), the non-protonic ionic liquid is one of tetraphenylphosphonium chloride ([Ph4P][Cl]), tetrabutylphosphonium bromide ([P4444][Br]), tetrabutylammonium bromide ([N4444][Br]), and butylmethylimidazolium bromide ([Bmim][Br]); the lithium salt of the fluorine-containing compound is one of bistrifluoromethylsulfonyl imide lithium salt ([TF2N][Li]), phenyl trifluoromethyl acetylacetonate lithium salt ([BTFA][Li]), hexafluoroacetylacetonate lithium salt ([HFA][Li]), thiophene trifluoromethyl acetylacetonate lithium salt ([TTFA][Li]), furan trifluoromethyl acetylacetonate lithium salt ([FTFA][Li]), and lithium hexafluorophosphate ([PF6][Li]).

[0008] Furthermore, in step 1), the molar ratio of the non-protonic ionic liquid to the lithium salt of the fluorine-containing compound 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 hydrophobic ionic liquid to the cross-linking agent is 1:1-7; the molar ratio of the hydrophobic 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 hydrophobic ionic liquid-embedded 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 proposes an application of a hydrophobic ionic liquid-embedded hyper-crosslinked polymer, wherein the application is to use the obtained hydrophobic ionic liquid-embedded hyper-crosslinked polymer for selectively adsorbing toluene vapor.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The present invention uses a hydrophobic ionic liquid as an embedded body, and by adjusting the ratio of the ionic liquid to the cross-linking building block, the ionic liquid is embedded in the hyper-cross-linked polymer composed of the cross-linking agent, thereby obtaining a type of hydrophobic ionic liquid-embedded hyper-cross-linked polymer. The hydrophobic ionic liquid-embedded hyper-cross-linked polymer prepared by the present invention has a hyper-cross-linked network structure, a large specific surface area, and contains abundant ionic liquid sites. It not only has a high hydrophobicity, but also has a good adsorption capacity for toluene vapor, and can significantly capture toluene vapor under high humidity conditions; 2) The hydrophobic ionic liquid-embedded hyper-crosslinked polymer prepared by the present invention has a high specific surface area, a high total pore volume and exposed ionic liquid sites, which significantly improves the toluene vapor adsorption and separation capacity, thereby achieving efficient, high-capacity, selective and reversible adsorption of toluene vapor under high humidity conditions; 3) When the molar ratio of the hydrophobic ionic liquid to the crosslinking agent of the present invention is 5:5, the hydrophobic ionic liquid embedded hypercrosslinked polymer has abundant pores, and the BET specific surface area reaches m 2 .g -1 , the water contact angle is 110°, and the toluene adsorption capacity is 270 mg. g at 80% humidity and toluene concentration of 2000 ppm. -1 ; 4) The hydrophobic ionic liquid-embedded hyper-crosslinked polymer adsorbent 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 hydrophobic ionic liquid-embedded hyper-cross-linked polymer, high selective adsorption of toluene vapor, etc., and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The infrared spectrum of the hydrophobic ionic liquid embedded hyper-crosslinked polymer [Tf2N]-ILHCP of the present invention; Figure 2 This is a scanning electron microscope photograph of the hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP of the present invention; Figure 3 The dispersion mapping energy spectrum of the hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP of the present invention; Figure 4 The X-ray photoelectron spectrum of the hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP of the present invention; Figure 5 Thermogravimetric curve of the hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP of the present invention; Figure 6 The solid-state nuclear magnetic resonance spectrum of the hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP of the present invention; Figure 7 The water contact angle of the hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP of the present invention; Figure 8 This is the nitrogen adsorption curve of the hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP under 77K conditions of the present invention; Fig. 9 This is the cyclic adsorption curve of toluene vapor at 80% humidity at 298K for the hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP of the present invention. 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 [Tf2N]-ILHCP Tetraphenylphosphonium chloride ([Ph4P][Cl]) and equimolar bis(trifluoromethylsulfonyl imide) lithium salt ([TF2N][Li]) were mixed, and stirred for 3 hours under the condition of 60°C water as a solvent, and then the reacted material was cooled to room temperature to form a phase-separated, transparent and stable liquid, and the obtained organic phase was vacuum dried at 60°C for 12 hours to obtain [Ph4P][TF2N] ionic liquid; Under a nitrogen atmosphere, a reaction mixture containing [Ph4P][TF2N] (5 mmol), p-dichlorobenzyl (DCX) (5 mmol), dichloroethane (DCE) (70 ml) and ferric chloride (20 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, a hyper-crosslinked polymer [Tf2N]-ILHCP based on [Ph4P][TF2N] 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 the peaks at 1498, 1596 and 1674 cm -1 A series of characteristic peaks at 925 cm reflect the stretching vibration of the backbone 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 vibration of the crosslinker methylene bridge (-CH2-) in the protic ionic liquid hypercrosslinked polymer; -1 The absorption peaks at 1059 and 1197 cm are the S=O stretching vibrations of the anion; -1 The absorption peaks at are the stretching vibrations of -SNS- and -CF3 on the anion.

[0019] Depend on Figure 2 SEM image analysis shows that there are abundant pores in the proton-type ionic liquid hyper-cross-linked polymers.

[0020] Depend on Figure 3 From the EDS mapping image analysis, it can be seen that carbon, phosphorus, nitrogen, oxygen, fluorine and sulfur elements are evenly dispersed throughout the polymer backbone, indicating that the hydrophobic ionic liquid is evenly dispersed in the network of the hyper-cross-linked polymer.

[0021] Depend on Figure 4 X-ray photoelectron spectroscopy analysis revealed that the characteristic peaks of C 1s, O 1s and F 1s are located at 282.1, 532.1 and 688.1 eV, respectively.

[0022] Depend on Figure 5Thermogravimetric analysis shows that at temperatures below 300°C, the sample loss is less than 10%, indicating that the proton-type ionic liquid hyper-crosslinked polymer has excellent thermal stability.

[0023] Depend on Figure 6 From the solid-state NMR spectrum analysis, 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 carbon in the methylene linker (-CH2-) and the carbon of the terminal chloromethyl group (-CH2Cl). The asterisk indicates the shoulder peak.

[0024] Depend on Figure 7 The water contact angle analysis showed that the water contact angle of the sample was 110.5°, indicating that the ionic liquid-embedded hyper-cross-linked polymer had excellent hydrophobicity. Example 2

[0025] Nitrogen adsorption measurement: The absorption device adopts the BET method. The hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP synthesized in Example 1 is first subjected to vacuum degassing activation treatment, and then the gas adsorption temperature is controlled to 77K and the gas pressure is controlled to 0~100kPa. The equilibrium absorption capacity is measured and the data is recorded.

[0026] The nitrogen adsorption results are as follows Figure 8 As shown, it is converted to a BET specific surface area of ​​770 m 2 .g -1 . Example 3

[0027] Cyclic adsorption measurement of 2000ppm toluene vapor under 80% humidity conditions: The adsorption-desorption device adopts a penetration method. The hydrophobic ionic liquid-embedded hyper-crosslinked polymer [Tf2N]-ILHCP synthesized in Example 1 is first subjected to vacuum degassing activation treatment, and then the gas adsorption temperature is controlled to 298K, the penetration adsorption capacity is measured, and the data is recorded by a computer. Desorption at 353K shows that desorption is difficult, while desorption can be completely performed at 393K. The cyclic absorption-desorption results are shown in 9, indicating that the cyclic absorption has good stability.

Claims

1. A method for preparing a hydrophobic ionic liquid-embedded hyper-crosslinked polymer, characterized in that The steps include: 1) Preparation of ionic liquid: a non-protonic ionic liquid is mixed with a lithium salt of a fluorine-containing compound, and the reaction is carried out in an aqueous phase as a solvent under stirring conditions. After the reaction is completed, the obtained organic phase liquid is vacuum dried, and the product collected after drying is the desired hydrophobic ionic liquid; 2) Hypercrosslinking reaction: Under a nitrogen atmosphere, the hydrophobic 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 carry out a hypercrosslinking reaction 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 hydrophobic ionic liquid-embedded hypercrosslinked polymer to be prepared.

2. The method for preparing a hydrophobic ionic liquid-embedded hyper-crosslinked polymer according to claim 1, characterized in that In step 1), the non-protonic ionic liquid is one of tetraphenylphosphonium chloride, tetrabutylphosphonium bromide, tetrabutylammonium bromide, and butylmethylimidazolium bromide; the lithium salt of the fluorine-containing compound is one of bistrifluoromethylsulfonyl imide lithium salt, phenyl trifluoromethyl acetylacetonate lithium salt, hexafluoroacetylacetonate lithium salt, thiophene trifluoromethyl acetylacetonate lithium salt, furan trifluoromethyl acetylacetonate lithium salt, and lithium hexafluorophosphate.

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

4. The method for preparing a hydrophobic ionic liquid-embedded hyper-crosslinked 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 hydrophobic ionic liquid-embedded hyper-crosslinked polymer according to claim 1, characterized in that In step 2), the molar ratio of the hydrophobic ionic liquid to the cross-linking agent is 1:1-7; the molar ratio of the hydrophobic 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 hydrophobic ionic liquid-embedded hyper-crosslinked polymer prepared by the method according to any one of claims 1 to 5.

7. The hydrophobic ionic liquid-embedded hyper-crosslinked polymer according to claim 6, characterized in that The typical chemical structure of the polymer is shown in Formula I below:

8. A use of a hydrophobic ionic liquid to embed a hyper-crosslinked polymer as claimed in claim 6, characterized in that The application is to embed the obtained hydrophobic ionic liquid into the hyper-crosslinked polymer for selective adsorption of toluene vapor.

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