Porous liquid based on porous object grafting site transfer and preparation method and application thereof

Abstract

The invention discloses porous liquid based on porous object grafting site transfer and a preparation method and application thereof, and particularly relates to the field of porous liquid. Comprising a porous object and a steric hindrance solvent, wherein the porous object is a two-dimensional nanosheet porous material; mixing the porous material and the two-dimensional nanosheet to obtain a two-dimensional nanosheet porous material; and mixing a silane coupling agent and an amino-containing steric hindrance solvent in a solvent, and mixing with the two-dimensional nanosheet porous material to obtain the porous liquid. According to the method, the two-dimensional nanosheet and the steric hindrance solvent are subjected to covalent bond combination through the silane coupling agent, so that the steric hindrance solvent is covalently grafted on the surface of the two-dimensional nanosheet, pore blockage and adsorption site failure of the porous material caused by direct action of the porous material and the steric hindrance solvent are avoided, and the adsorption performance is further improved.

Description

Technical Field

[0001] The present application relates to the field of porous liquids, and in particular to a porous liquid based on porous guest grafting site transfer, and a preparation method and application thereof. Background Art

[0002] Currently, CO2 capture primarily involves chemical / physical solvent absorption, cryogenic distillation, adsorption separation, and membrane separation. Separation materials used include liquid absorbents (such as alcoholamine solutions), porous solid materials (porous carbon, zeolite molecular sieves, metal-organic frameworks, etc.), and membrane materials. Pressure swing adsorption, which relies on porous solid materials in industry, suffers from difficulties and high costs in adsorbent preparation, as well as mechanical damage.

[0003] Existing capture materials are primarily divided into solid adsorbents (such as activated carbon and zeolite molecular sieves) and liquid absorbents (such as alcoholamine solutions and hot potash solutions). However, both types of materials have significant drawbacks: solid adsorbents, while porous, lack fluidity, making industrial recycling difficult, their adsorption capacity limited, and their pore structure susceptible to damage by impurities. Liquid absorbents, while offering good fluidity and absorption rates, suffer from volatilization, strong corrosiveness, and high energy consumption, making it difficult to balance environmental and economic considerations. This limits their application in industrial production.

[0004] Porous liquids (PLs), as a new type of porous material, effectively combine the excellent properties of porous solid adsorbents (permanent pores, precise identification, etc.) with the significant advantages of liquid absorbents (fluidity, rapid mass transfer, etc.). They have the potential to be directly integrated into existing solvent absorption infrastructure to achieve continuous separation, thereby significantly reducing equipment investment. They can also reduce regeneration energy consumption by utilizing physical adsorption rather than chemical adsorption. Porous liquids based on metal-organic frameworks (MOFs) in particular offer significant advantages (such as simple preparation and highly modular design) and have become the most promising class. However, their performance lags significantly behind that of existing porous solid adsorbents. This is because the porous guest components of porous liquids are in direct contact with sterically hindered solvents, which leads to pore clogging and loss of adsorption sites, thus compromising gas adsorption performance. Summary of the Invention

[0005] The main purpose of this application is to provide a porous liquid based on porous guest grafting site transfer and its preparation method and application, aiming to solve the poor gas adsorption performance of existing porous liquids.

[0006] To achieve the above-mentioned purpose, the present application provides a porous liquid based on porous guest grafting site transfer, comprising a porous guest and a steric solvent; wherein, the porous guest is prepared by two-dimensional nanosheets and porous materials, the porous material is uniformly dispersed on the surface of the two-dimensional nanosheets, and the steric solvent is covalently grafted on the surface of the two-dimensional nanosheets.

[0007] Optionally, the mass ratio of the two-dimensional nanosheet to the porous material is 0.5-2:1, and the surface area of the two-dimensional nanosheet is 50-100 m 2 / g.

[0008] Optionally, the porous liquid is prepared by a porous guest, a hindered solvent and a silane coupling agent; the mass ratio of the porous guest to the hindered solvent is 1:20-22, and the molar ratio of the silane coupling agent to the hindered solvent is 1:1-4.

[0009] Optionally, the surface of the two-dimensional nanosheet contains hydroxyl groups, the hindered solvent contains amino groups, and the porous guest and the hindered solvent are bridged by a silane coupling agent; wherein the silanol groups generated by the hydrolysis of the silane coupling agent react with the hydroxyl groups of the two-dimensional nanosheet through dehydration condensation, and are covalently bonded to the amino groups of the hindered solvent through epoxy groups.

[0010] Optionally, the porous material includes MOFs material, zeolite molecular sieve or porous carbon; the two-dimensional nanosheet includes vermiculite nanosheet, graphene oxide or Michaelene nanosheet.

[0011] Optionally, the silane coupling agent includes KH560, γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane or N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; the hindered solvent includes polyetheramine M-2070, polyetheramine D-2000, and polyetheramine T-5000.

[0012] To achieve the above-mentioned purpose, the present application also provides a method for preparing a porous liquid based on porous guest grafting site transfer, comprising: stirring a porous material and a two-dimensional nanosheet at 38-42°C for 1-3 hours to obtain a two-dimensional nanosheet@porous material; mixing a silane coupling agent and an amino-containing steric hindered solvent in a solvent, and stirring at 48-52°C for 6-10 hours to obtain a first reaction liquid; dispersing the two-dimensional nanosheet@porous material in H2O, and heating and stirring at 30-40°C for 6-10 hours to obtain a second reaction liquid; mixing the first reaction liquid and the second reaction liquid and dialyzing to obtain a porous liquid.

[0013] To achieve the above objectives, the present application also provides an application of a porous liquid based on the transfer of porous guest grafting sites in the field of gas adsorption.

[0014] Optionally, the gas is CO2, N2 or CH4.

[0015] Compared with the prior art, the present invention has the following advantages: The present invention uses a porous liquid based on the transfer of porous guest grafting sites to prepare a two-dimensional nanosheet@porous material composite structure. The high specific surface area and nanometer-scale thickness of the two-dimensional nanosheet can evenly disperse the porous material and provide interfacial grafting sites, preventing the solvent from directly interacting with the porous material pores. As a result, the interaction sites between the porous guest and the hindered solvent are transferred to the surface of the two-dimensional nanosheet, protecting its inherent pore structure and adsorption sites. A silane coupling agent is used to covalently bond the two-dimensional nanosheet and the hindered solvent, allowing the hindered solvent to be covalently grafted onto the surface of the two-dimensional nanosheet. This prevents clogging of the porous material pores and loss of adsorption sites caused by direct interaction between the porous material and the hindered solvent, thereby improving adsorption performance. The present invention's method for preparing a porous liquid based on the transfer of porous guest grafting sites is simple to operate and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of a porous liquid based on porous guest grafting site transfer in this application; Figure 2 This is a reaction mechanism diagram of a porous liquid based on the transfer of porous guest grafting sites in this application; Figure 3 This application provides an adsorption site map of a porous liquid based on porous guest grafting site transfer; Figure 4 This is a schematic diagram of XRD of UiO-66 of Example 1 of the present application; Figure 5 This is a SEM schematic diagram of UiO-66 of Example 1 of the present application; Figure 6 This is a SEM image of the original sample of vermiculite in Example 1 of the present application; Figure 7 This is an SEM image of the vermiculite nanosheets of Example 1 of the present application; Figure 8 This is the SEM image of the composite VNMs@UiO-66 of Example 1 of the present application.

[0017] Figure 9 FT-IR images of VNMs@UiO-66PLs of Examples 1-3 of the present application; Figure 10 Attached are the CO2 adsorption-desorption diagrams of the porous liquids of Examples 1-3 of the present application and the comparative example.

[0018] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0020] The first embodiment of the present invention provides a porous liquid based on porous guest grafting site transfer, comprising a porous guest and a steric solvent, such as Figure 1 As shown, the porous guest is a two-dimensional nanosheet@porous material. The raw materials of the porous guest include two-dimensional nanosheets and a porous material. The porous material is uniformly physically dispersed on the surface of the two-dimensional nanosheets, and the hindered solvent is covalently grafted onto the surface of the two-dimensional nanosheets. The two-dimensional nanosheets have large lateral dimensions and a high specific surface area with nanometer-scale thickness. The two-dimensional nanosheets contain hydroxyl groups on their surfaces, and the hindered solvent contains amino groups. The porous guest and the hindered solvent are bridged by a silane coupling agent. The silanol groups generated by the hydrolysis of the silane coupling agent react with the hydroxyl groups of the two-dimensional nanosheets through dehydration condensation, and then covalently bond to the amino groups of the hindered solvent through epoxy groups.

[0021] In this embodiment, the high specific surface area and nanometer-scale thickness of the two-dimensional nanosheets can evenly disperse the porous material and provide interface grafting sites, thereby transferring the action sites of the porous guest and the hindered solvent to the surface of the two-dimensional nanosheet, avoiding the blockage of the pores and adsorption sites of the porous material; the two-dimensional nanosheets and the hindered solvent are covalently bonded through the silane coupling agent, so that the hindered solvent is covalently grafted on the surface of the two-dimensional nanosheet, avoiding the blockage of the porous guest pores and the failure of the adsorption sites caused by the direct action of the porous guest and the hindered solvent, thereby improving the adsorption performance.

[0022] A second embodiment of the present invention provides a method for preparing a porous liquid based on porous guest grafting site transfer, comprising: Step S1, stirring the porous material and the two-dimensional nanosheets at 38-42° C. for 1-3 hours (physical mixing), centrifuging, and drying the precipitate to obtain the two-dimensional nanosheets@porous material; The mass ratio of the two-dimensional nanosheets to the porous material is 0.5-2:1. The two-dimensional nanosheets contain hydroxyl groups on their surface and have a high specific surface area characteristic of large lateral dimensions and nanometer-scale thickness. The porous material can be a MOFs material (such as UiO-66), a zeolite molecular sieve, or a porous carbon. The two-dimensional nanosheets include vermiculite (VNMs) nanosheets, graphene oxide (GO), or mikkelene nanosheets (MXene). For example, the specific surface area of the VNMs nanosheets is 50-100 m 2 / g.

[0023] Step S2: Mixing a silane coupling agent and an amino-containing hindered solvent in a solvent at a mass molar ratio of 1:1-4 and stirring at 48-52°C for 6-10 hours to obtain a first reaction solution; dispersing the two-dimensional nanosheet@porous material in H2O and heating and stirring at 30-40°C for 6-10 hours to obtain a second reaction solution; mixing the first and second reaction solutions, dialyzing, and drying to obtain a porous liquid. The mass ratio of the porous guest to the hindered solvent is 1:20-22.

[0024] The mechanism of the above reaction is that the epoxy group of the silane coupling agent reacts with the amino group of the hindered solvent, and then the silanol Si-OH generated by the hydrolysis of the silane coupling agent dehydrates and condenses with the hydroxyl groups on the surface of the two-dimensional nanosheets in the two-dimensional nanosheet@porous material to obtain a porous liquid of the two-dimensional nanosheet@porous material with fluidity.

[0025] Among them, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane (KH560), γ-aminopropyltriethoxysilane (KH550), N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH792) or N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane (KH602); the hindered solvent is polyetheramine M-2070, polyetheramine D-2000, and polyetheramine T-5000.

[0026] For example, the silane coupling agent is KH560, the hindered solvent is polyetheramine M-2070, the porous material is UiO-66, and the two-dimensional nanosheet is VNMs nanosheet. The reaction principle is as follows: Figure 2 As shown, KH560 is hydrolyzed to generate silanol Si-OH, the epoxy group of KH560 reacts with the amino group of polyetheramine M-2070, and then dehydrates and condenses with the hydroxyl groups on the surface of VNMs nanosheets to obtain porous liquid VNMs@UiO-66PLs.

[0027] In this embodiment, porous materials and two-dimensional nanosheets are mixed, and the high specific surface area (50-100m 2 / g) and nanoscale thickness, uniformly dispersing the porous material and providing interfacial grafting sites to prevent the solvent from directly acting on the MOFs pores; then, through silane coupling agent bridging, the steric solvent is covalently grafted onto the surface of the two-dimensional nanosheets, protecting the inherent pore structure and adsorption sites of the porous material, and realizing the porous guest site transfer strategy.

[0028] The third embodiment of the present invention provides an application of a porous liquid based on porous guest grafting site transfer in the field of gas adsorption, wherein the gas is CO2, N2 or CH4.

[0029] In this example, a porous liquid was used to selectively capture CO2. Based on the structures of the porous guest and hindered solvent, the Lewis acid-base interaction between the polyetheramine in the hindered solvent M2070 and CO2, combined with the cavity structure of the porous guest, facilitated gas adsorption, identified CO2 adsorption sites, and revealed the mechanism of CO2 selective adsorption.

[0030] For example, Figure 3 As shown, the porous liquid is VNMs@UiO-66PLs. VNMs@UiO-66PLs has three adsorption sites for CO2 adsorption. The first adsorption site is the amine group on the organic long chain, which can react with CO2. The second adsorption site is the ether bond on the organic long chain on the surface of the porous liquid, which can form a Lewis acid-base interaction with CO2 molecules, thereby adsorbing CO2. The third adsorption site is the porous cavity structure of UiO-66. Secondly, CO2 molecules can also enter the interstices formed by the entanglement of organic long chains on the surface of the porous liquid. By loading UiO-66 nanoparticles onto vermiculite nanosheets and grafting polymer chains onto this material, the pores of the UiO-66 nanoparticles will not be blocked by steric solvents, and the adsorption sites will not be occupied, allowing more CO2 molecules to enter the permanent pore structure of UiO-66, thereby improving the CO2 adsorption capacity of VNMs@UiO-66PLs.

[0031] Example 1 Step S1: UiO-66 MOFs were prepared using a solvothermal method, and VNM nanosheets were prepared using a chemical exfoliation coupled with physical ultrasound. Specifically, 0.48 g of ZrCl₄ was added to 60 mL of DMF and sonicated for 5 minutes until no granular precipitate remained in the solution, completely dissolving the ZrCl₄ in the DMF. 6 mL of acetic acid was added and stirred thoroughly on a quadruple stirrer for approximately 10 minutes until completely mixed, yielding a mixed solution. 0.342 g of BDC was then added to the mixed solution and stirred thoroughly on a quadruple stirrer at room temperature for approximately 1 hour until no solids remained, yielding the reaction product. The reaction product was transferred to a covered glass bottle and placed in a preheated 120°C electric forced air drying oven for crystallization. After 24 hours, the oven was removed from the oven and allowed to cool naturally to room temperature. The solution was then centrifuged at 8000 rpm to completely separate the solids. Centrifugation was complete when a white precipitate emerged and the solution became colorless and transparent. The liquid was poured out and the white precipitate was further dissolved in DMF. The solution was washed and centrifuged three times, and then the solution was washed and centrifuged three times in anhydrous methanol. Finally, the white precipitate was placed in a vacuum drying oven at 120°C and dried overnight to obtain white UiO-66 powder. Sieve 2g of vermiculite (40 mesh) and 100mL of the prepared supersaturated NaCl solution and add them to a 200ml round-bottom flask, heat and stir at 120°C in an oil bath for 24h, then wash and centrifuge (6000r / min, 5min) 3~5 times, add the obtained Na+ exchanged vermiculite and 100mL of the prepared LiCl (2mol / L) solution to a 200ml round-bottom flask, heat and stir at 120°C in an oil bath for 24h to obtain Li+ exchanged vermiculite, then wash and centrifuge (6000r / min, 5min) 3~5 times, add the obtained Li+ exchanged vermiculite and 100mL of hydrogen peroxide to a 200ml round-bottom flask, heat and stir at 110°C in an oil bath for 24h, wash 3~5 times, disperse in water, and stir overnight. The vermiculite nanosheet dispersion was obtained by dispersing the sample using an ultrasonic cleaner and then centrifuging it (6000 rpm for 60 min). The concentration of the dispersion was then measured by solvent evaporation. Step S2: 30 ml of a 0.3 mg / ml vermiculite dispersion was ultrasonically dissolved with 0.1 g of UiO-66 and stirred at 40°C for 2 hours. The mixture was then centrifuged at 5000 rpm for 5 minutes. The precipitate was dried in a preheated electric blast drying oven at 75°C for 24 hours to obtain a VNMs@UiO-66 composite. In step S3, 0.236g of KH560, 2.1g of M2070, and 20ml of methanol were placed sequentially into a 200ml round-bottom flask and stirred at 50°C for 8 hours to obtain a first reaction solution. 3ml of HO was added to 0.1g of the VNMs@UiO-66 complex, and the solution was dissolved by ultrasonication until no solids remained. The solution was then heated and stirred at 35°C for 8 hours to obtain a second reaction solution. The first and second reaction solutions were placed in a dialysis bag and dialyzed in a large beaker containing 2L of water for 48 hours, changing the water three times. The dialyzed solution was then poured into a beaker and placed in a preheated electric forced air drying oven at 75°C to dry out the water, resulting in VNMs@UiO-66PLs.

[0032] The UiO-66 and VNMs nanosheets prepared in this example were tested. Figure 4 It can be seen that UiO-66 is a regular octahedral crystal with uniform size; Figure 5 It can be seen that the UiO-66 skeleton structure is complete. Figure 6 As shown in the figure, the scanning electron microscope (SEM) of the vermiculite sample shows that the vermiculite has a clear flaky structure, and some of the flaky layers are cross-linked or stacked. Figure 7 As shown, the VNMs nanosheets were exfoliated into single-layer vermiculite nanosheets with larger lateral dimensions and smooth and defect-free surfaces.

[0033] Example 2 The difference from Example 1 is that in step S2, the mass ratio of UiO-66 and VNMs nanosheets is 1:1.

[0034] Example 3 The difference from Example 1 is that in step S2, the mass ratio of UiO-66 to VNMs nanosheets is 2:1.

[0035] Comparative Example The MOFs material UiO-66 was mixed with KH560 and M2070, a neck layer of KH560 was grafted on the surface of UiO-66, and M2070 was grafted as a crown layer through covalent bonds to obtain UiO-66 porous liquid.

[0036] The composite VNMs@UiO-66 obtained in Examples 1-3 was tested by scanning electron microscopy, and the test results are as follows. Figure 8 It can be seen that the composite VNMs@UiO-66 obtained in Examples 1-3 was characterized and analyzed, and scanning electron microscopy showed that the loading condition was good.

[0037] The N2 adsorption-desorption test shows that the N2 adsorption-desorption curve of the composite VNMs@UiO-66 obtained in Examples 1-3 is type I, which is a unique adsorption curve type for microporous materials; the specific surface areas of the composite VNMS@UiO-66 obtained in Examples 1-3 are 1134 m 2 / g、860m 2 / g、508m 2 / g, which indicates that with the increase of VNMs loading, excessive VNMs may fill the micropores of UiO-66 or cover its surface, resulting in a decrease in specific surface area.

[0038] like Figure 9 As shown in the Fourier infrared spectra of three different ratios of VNMs@UiO-66PLs, it can be seen that KH560 forms C-O-Si grafted on the surface of VNMs by dehydration condensation, 709 cm -1 The absorption vibration peak of C—O—Si is at 3300~3500cm. The epoxy group on KH560 is grafted with the terminal primary amino group on polyetheramine M2070 through a ring-opening reaction, so the primary amino group is at 3300~3500cm -1 The double peaks in the band and at 1950cm -1 The medium intensity absorption peaks at 1290 cm -1 The absorption peak at 2860 cm is the characteristic peak of secondary amine, indicating that the primary amine reacts to form a secondary amine; -1 The peak at 1641cm is the characteristic peak of -CH3 on the M2070 molecular chain, which also indicates that the organic matter is successfully coated on the surface of VNMs@UiO-66. -1The N-H in-plane bending vibration absorption peak is at 1189cm -1 The absorption peak of fatty amine is at 1120 cm -1 The C—O stretching vibration absorption peak of the ether bond is at 1471 cm -1 The presence of the above infrared absorption peaks indicates that VNMs@UiO-66PLs were successfully prepared.

[0039] The CO2 adsorption performance of the porous liquids obtained in Examples 1-3 and the comparative example was evaluated. Figure 10 It can be seen that the CO2 adsorption capacity of VNMs@UiO-66PLs is improved compared with UiO-66-OHPLs, and the adsorption performance of VNMs@UiO-66PLs with a ratio of 2:1 is better than that of the other two ratios.

[0040] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A porous liquid based on porous guest grafting site transfer, characterized in that: including porous guests and hindered solvents; Wherein, the porous guest is a two-dimensional nanosheet@porous material; The porous guest is prepared by two-dimensional nanosheets and porous materials. The porous material is uniformly dispersed on the surface of the two-dimensional nanosheets, and the steric hindered solvent is covalently grafted on the surface of the two-dimensional nanosheets.

2. A porous liquid based on porous guest grafting site transfer according to claim 1, characterized in that: The mass ratio of the two-dimensional nanosheet to the porous material is 0.5-2:1, and the surface area of the two-dimensional nanosheet is 50-100 m 2 / g.

3. A porous liquid based on porous guest grafting site transfer according to claim 1, characterized in that: The porous liquid is prepared by using a porous guest, a hindered solvent and a silane coupling agent; The mass ratio of the porous guest to the steric hindered solvent is 1:20-22, and the molar ratio of the silane coupling agent to the steric hindered solvent is 1:1-4.

4. A porous liquid based on porous guest grafting site transfer according to claim 1, characterized in that: The surface of the two-dimensional nanosheet contains hydroxyl groups, the hindered solvent contains amino groups, and the porous guest and the hindered solvent are bridged by a silane coupling agent; The silanol groups generated by the hydrolysis of the silane coupling agent react with the hydroxyl groups of the two-dimensional nanosheets through dehydration condensation, and are covalently bonded to the amino groups of the hindered solvent through the epoxy groups.

5. A porous liquid based on porous guest grafting site transfer according to claim 1, characterized in that: Porous materials include MOFs materials, zeolite molecular sieves or porous carbon; two-dimensional nanosheets include vermiculite nanosheets, graphene oxide or Michaelene nanosheets.

6. A porous liquid based on porous guest grafting site transfer according to claim 1, characterized in that: The silane coupling agent includes KH560, γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane or N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; the hindered solvent includes polyetheramine M-2070, polyetheramine D-2000, and polyetheramine T-5000.

7. A method for preparing a porous liquid based on porous guest grafting site transfer according to claim 1, characterized in that: include: Stir the porous material and the two-dimensional nanosheet at 38-42°C for 1-3 h to obtain the two-dimensional nanosheet@porous material; Mixing a silane coupling agent and an amino-containing hindered solvent in a solvent, and stirring at 48-52° C. for 6-10 hours to obtain a first reaction solution; Dispersing the two-dimensional nanosheet@porous material in H2O, and heating and stirring at 30-40°C for 6-10 hours to obtain a second reaction solution; The first reaction liquid and the second reaction liquid are mixed and dialyzed to obtain a porous liquid.

8. Use of the porous liquid based on porous guest grafting site transfer according to claim 1 in the field of gas adsorption.

9. The use of porous liquid based on porous guest grafting site transfer in the field of gas adsorption according to claim 8, characterized in that: The gas is CO2, N2 or CH4.

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