A hydrophobic core-shell material based on ionic liquid / metal-organic framework / super-cross-linked polymer, a preparation method thereof and application of the material in selective adsorption of toluene vapor under high humidity

Abstract

The application discloses a hydrophobic core-shell material based on an ionic liquid / metal organic framework / ultra-cross-linked polymer, a preparation method thereof and application of the hydrophobic core-shell material in selective adsorption of toluene vapor under high humidity, wherein the metal organic framework is used as an embedded body (core), and the hydrophobic ionic liquid ultra-cross-linked polymer (shell) is coated on the outside to obtain a hydrophobic core-shell material based on the ionic liquid / metal organic framework / ultra-cross-linked polymer. The hydrophobic core-shell material prepared by the application has an internal metal organic framework cavity and an external ultra-cross-linked network structure, a large specific surface area, and rich ionic liquid sites. The hydrophobic core-shell material not only has high hydrophobicity, but also can obviously improve toluene vapor adsorption and separation capacity, so that efficient, high-capacity and selective reversible adsorption of toluene vapor under high humidity can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrophobic polymer synthesis, and particularly relates to a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer, a preparation method thereof, and an application thereof in selectively adsorbing toluene vapor under high humidity. Background Art

[0002] Organic solvents are used extensively in industrial chemical production processes, and in particular, benzene series compounds, represented by toluene, are released into the atmosphere during processing, forming air pollutants that pollute the environment and threaten people's health. Therefore, effective treatment of volatile organic compounds (VOCs), represented by toluene, has attracted widespread attention. Catalytic combustion is a commonly used method for treating VOCs, but this method is not only energy-intensive but also produces secondary pollution. Furthermore, VOCs are typically accompanied by large amounts of water vapor when discharged. Therefore, developing novel hydrophobic adsorbents to efficiently adsorb VOCs such as toluene under humid conditions is very important.

[0003] At present, ionic liquids, as a special solvent, are non-volatile, do not cause secondary pollution, have good solubility, high thermal stability, and can be designed in structure, and have attracted people's attention. For example, Dai et al. reported the capture of toluene by imidazole-based ionic liquids (ACS Sustainable Chem. Eng. 2020, 8 (24), 9058-9069). However, ionic liquids have a high viscosity. In recent years, combining ionic liquids with porous materials to capture and separate toluene has become a hot topic. For example, Li et al. reported the adsorption of toluene by imidazole-type ionic liquids combined with activated carbon (Environ. Sci. Pollut., 2024, 31, 35553–35566); Ramos et al. reported the adsorption of toluene by carboxylic acid ionic liquids and metal-organic framework material MIL-101. However, although the adsorption capacity is improved compared with the original adsorbent, the adsorption is not dominant under humid conditions. Therefore, for the adsorption of toluene under humid conditions, it is very meaningful to develop a new type of composite adsorbent based on hydrophobic core-shell materials of ionic liquid / metal organic framework / hyper-cross-linked polymer by structural adjustment, which is prepared by Friedel-Crafts reaction of ionic liquid and metal organic framework through cross-linking agent to improve the selective adsorption capacity of toluene under high humidity conditions. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention aims to provide a hydrophobic core-shell material based on an ionic liquid / metal-organic framework / hypercrosslinked polymer, a preparation method thereof, and its application in selective adsorption of toluene vapor under high humidity. The hydrophobic core-shell material obtained by the present invention has metal-organic framework pores within and a hypercrosslinked network structure doped with a hydrophobic ionic liquid on the outside. By utilizing the internal cavities, high specific surface area, high total pore volume, and exposed ionic liquid sites, it significantly improves the adsorption capacity for selective adsorption of toluene vapor under high humidity conditions, thereby achieving efficient, high-capacity, and reversible selective adsorption of toluene vapor.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for preparing a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer comprises the following steps:

[0007] 1) Preparation of ionic liquid: An aprotic ionic liquid is mixed with a lithium salt of a fluorine-containing compound, and the mixture is reacted with water as a solvent under stirring. After the reaction, the obtained organic phase liquid is vacuum dried. The product collected after drying is the desired hydrophobic ionic liquid;

[0008] 2) Preparation of a Metal-Organic Framework: Dissolve copper nitrate in water to obtain solution 1, and dissolve trimesic acid in ethanol to obtain solution 2. Stir the two solutions evenly, transfer them to a reactor, and place them in an oven for reaction. The product is washed with water, washed with ethanol, and dried to obtain the desired metal-organic framework.

[0009] 3) Hypercrosslinking reaction: Under a nitrogen atmosphere, the hydrophobic ionic liquid obtained in step 1) and the metal organic framework obtained in step 2) are 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 filtered, and 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 core-shell material of the ionic liquid / metal organic framework / hypercrosslinked polymer to be prepared.

[0010] Furthermore, in step 1), the aprotic 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 lithium salt of bis(trifluoromethylsulfonyl imide)

[0011] ([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]), lithium hexafluorophosphate ([PF6][Li]).

[0012] Furthermore, in step 1), the molar ratio of the aprotic 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.

[0013] Furthermore, in step 2), the molar ratio of copper nitrate to trimesic acid is 1-2:1; the reaction temperature is 100-120° C.; and the reaction time is 12-24 hours.

[0014] Furthermore, in step 2), the mass ratio of copper nitrate to water is 0.05-0.3:1; the mass ratio of trimesic acid to ethanol is 0.2-0.4:1; the unit of mass is g, and the unit of volume is mL.

[0015] Furthermore, in step 3), the cross-linking 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.

[0016] Furthermore, in step 3), the molar ratio of the hydrophobic ionic liquid to the crosslinking agent and the Lewis acid is 0.3-7 mmol: 0.3-7 mmol: 1.2-28 mmol; the mass of the metal organic framework is 1-2 g; the reaction temperature is 25-100° C.; and the reaction time is 4-24 h.

[0017] The present invention proposes a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer.

[0018] Furthermore, the typical structural formula of the hydrophobic core-shell material is shown in Formula I below:

[0019]

[0020] The present invention also proposes an application of a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer, wherein the application is to use the obtained hydrophobic core-shell material for selectively adsorbing toluene vapor under high humidity conditions.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1) The present invention uses a metal organic framework as the embedded body (core) and coats the outside with a hydrophobic ionic liquid hypercrosslinked polymer (shell), thereby obtaining a type of hydrophobic core-shell material based on ionic liquid / metal organic framework / hypercrosslinked polymer. The hydrophobic core-shell material prepared by the present invention has an internal metal organic framework cavity and an external hypercrosslinked network structure, a large specific surface area, and contains abundant ionic liquid sites. It not only has a high hydrophobicity, but also can significantly improve the toluene vapor adsorption and separation capacity, thereby achieving efficient, high-capacity, and selective reversible adsorption of toluene vapor under high humidity conditions;

[0023] 3) When the molar ratio of the hydrophobic ionic liquid to the crosslinking agent is 3 mmol:3 mmol and the metal organic framework is 1 g, the hydrophobic core-shell material has abundant pores and a BET surface area of ​​700 to 900 m 2 g -1 The water contact angle is 110°, and the toluene adsorption capacity is 290 mg g at 80% humidity and a toluene concentration of 2000 ppm. -1 ;

[0024] 4) The present invention has the advantages of simple preparation process, large specific surface area of ​​the prepared hydrophobic core-shell material, high selective adsorption of toluene vapor, etc., and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope photo of the hydrophobic core-shell material [Tf2N]-ILHCP@CuBTC of the present invention;

[0026] Figure 2 This is the dispersion mapping energy spectrum of the hydrophobic core-shell material [Tf2N]-ILHCP@CuBTC of the present invention;

[0027] Figure 3 The X-ray diffraction pattern of the hydrophobic core-shell material [Tf2N]-ILHCP@CuBTC of the present invention;

[0028] Figure 4 The water contact angle of the hydrophobic core-shell material [Tf2N]-ILHCP@CuBTC of the present invention;

[0029] Figure 5 This is the nitrogen adsorption curve of the hydrophobic core-shell material [Tf2N]-ILHCP@CuBTC at 77K;

[0030] Figure 6 This is the penetration adsorption curve of toluene vapor under 80% humidity at 298K for the hydrophobic core-shell material [Tf2N]-ILHCP@CuBTC of the present invention. DETAILED DESCRIPTION

[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 described scope.

[0032] Example 1

[0033] 1) Synthesis of [Tf2N]-ILHCP@CuBTC

[0034] Tetraphenylphosphonium chloride ([Ph4P][Cl]) and equimolar lithium bis(trifluoromethylsulfonyl imide) salt ([TF2N][Li]) were mixed and stirred for 3 hours in water at 60°C as a solvent. The reacted material was then cooled to room temperature to form a phase-separated, transparent and stable liquid. The obtained organic phase was vacuum dried at 60°C for 12 hours to obtain a [Ph4P][TF2N] ionic liquid.

[0035] Dissolve 3.26 g of copper nitrate in 60 ml of water to obtain solution 1, and dissolve 1.58 g of trimesic acid in 60 ml of ethanol to obtain solution 2. Stir the two solutions evenly, transfer them to a reactor, and place them in an oven at 120°C for 12 hours. Wash the product with water, ethanol, and dry it to obtain Cu-BTC material.

[0036] Under a nitrogen atmosphere, a reaction mixture containing [Ph4P][TF2N] (3 mmol), Cu-BTC (1 g), p-dichlorobenzyl (DCX) (3 mmol), dichloroethane (DCE) (70 ml) and ferric chloride (20 mmol) was stirred at 80°C for 24 h. 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 h. After drying, a hypercrosslinked polymer [Tf2N]-ILHCP@CuBTC of a hydrophobic core-shell material [Ph4P][TF2N] based on an ionic liquid / metal organic framework / hypercrosslinked polymer was obtained.

[0037] 2) Material characterization:

[0038] Depend on Figure 1 Analysis of the SEM images shows that the left image shows the metal-organic framework CuBTC, while the right image shows the hydrophobic core-shell material [Tf2N]-ILHCP@CuBTC based on an ionic liquid / metal-organic framework / hypercrosslinked polymer. The two are clearly different. Furthermore, the core-shell material [Tf2N]-ILHCP@CuBTC has abundant pores.

[0039] Depend on Figure 2 EDS mapping image analysis shows that copper, sulfur, nitrogen, oxygen, and phosphorus elements are uniformly dispersed throughout the polymer backbone, indicating that the hydrophobic ionic liquid is uniformly dispersed in the network of the hyper-cross-linked polymer.

[0040] Depend on Figure 3 XRD pattern analysis shows that the hydrophobic core-shell material [Tf2N]-ILHCP@CuBTC based on ionic liquid / metal organic framework / hyper-cross-linked polymer is significantly different from the metal organic framework CuBTC, and the peak of CuBTC is greatly weakened in the XRD pattern of [Tf2N]-ILHCP@CuBTC.

[0041] Depend on Figure 4 The water contact angle analysis showed that the water contact angle of the sample was 103.2°, indicating that the ionic liquid-embedded hyper-cross-linked polymer had excellent hydrophobicity.

[0042] Example 2

[0043] Nitrogen adsorption measurement: The absorption device adopts the BET method. The hydrophobic ionic liquid-embedded hyper-cross-linked polymer [Tf2N]-ILHCP synthesized in Example 1 is first subjected to vacuum degassing activation treatment. 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.

[0044] Nitrogen adsorption results are as follows Figure 5 As shown, the BET specific surface area is 121.7m 2 g -1 .

[0045] Example 3

[0046] Cyclic adsorption measurement of 2000 ppm toluene vapor under 80% humidity: The adsorption and desorption apparatus used a penetration method. The hydrophobic ionic liquid-embedded hypercrosslinked polymer [Tf2N]-ILHCP synthesized in Example 1 was first subjected to vacuum degassing and activation. The gas adsorption temperature was then controlled at 298K. The penetration adsorption capacity was measured and the data recorded by a computer. The adsorption results, shown in Figure 6, indicate an adsorption capacity of 290 mg g -1 .

Claims

1. A method for preparing a hydrophobic core-shell material based on ionic liquid / metal organic framework / hypercrosslinked polymer, characterized in that The steps include: 1) Preparation of ionic liquid: An aprotic ionic liquid is mixed with a lithium salt of a fluorinated compound and reacted with water as a solvent under stirring. After the reaction, 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 of the fluorine-containing compound is lithium salt of bis(trifluoromethylsulfonylimide); 2) Preparation of the Metal-Organic Framework: Dissolve copper nitrate in water to obtain Solution 1, and dissolve trimesic acid in ethanol to obtain Solution 2. Stir the two solutions thoroughly, transfer them to a reactor, and place them in an oven for reaction. The product is washed with water, then with ethanol, and dried to obtain the desired Metal-Organic Framework material. 3) Hypercrosslinking reaction: Under a nitrogen atmosphere, the hydrophobic ionic liquid obtained in step 1) and the metal organic framework obtained in step 2) are 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 filtered, and the filtered precipitate is washed until the filtrate is clear and transparent. Finally, the washed precipitate is dried. The product collected after drying is the hydrophobic core-shell material of the ionic liquid / metal organic framework / hypercrosslinked polymer to be prepared; In step 3), the cross-linking agent is p-dichlorobenzyl or p-dibromobenzyl.

2. The method for preparing a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer according to claim 1, characterized in that In step 1), the molar ratio of the aprotic 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.

3. The method for preparing a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer according to claim 1, characterized in that In step 2), the ratio of copper nitrate to water by volume is 0.05-0.3:1; the ratio of trimesic acid to ethanol by volume is 0.2-0.4:1; the unit of mass is g, and the unit of volume is mL.

4. The method for preparing a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer according to claim 1, characterized in that In step 2), the molar ratio of copper nitrate to trimesic acid is 1-2:1; the reaction temperature is 100-120° C.; and the reaction time is 12-24 h.

5. The method for preparing a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer according to claim 1, characterized in that In step 3), the organic solvent is one of dichloromethane, chloroform, and dichloroethane; and the Lewis acid is one of aluminum chloride, ferric chloride, and zinc chloride.

6. The method for preparing a hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer according to claim 1, characterized in that In step 3), the molar ratio of the hydrophobic ionic liquid to the crosslinker and the Lewis acid is 0.3-7 mmol:0.3-7 mmol:1.2-28 mmol; the mass of the metal-organic framework is 1-2 g; the reaction temperature is 25-100° C.; and the reaction time is 4-24 h.

7. A hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer prepared by the method according to any one of claims 1 to 6.

8. The hydrophobic core-shell material based on ionic liquid / metal organic framework / hyper-crosslinked polymer according to claim 7, characterized in that The chemical structure of the hydrophobic core-shell material is shown in Formula I below: 。 9. A use of the hydrophobic core-shell material based on ionic liquid / metal organic framework / hypercrosslinked polymer as claimed in claim 7, characterized in that The application is to use the obtained hydrophobic core-shell material for selectively adsorbing toluene vapor under high humidity conditions.

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