Deep eutectic solvent modified porous organic cage material, mixed matrix membrane as well as preparation method and application of deep eutectic solvent modified porous organic cage material and mixed matrix membrane

Abstract

The invention provides a deep eutectic solvent modified porous organic cage material, a mixed matrix membrane and a preparation method and application thereof, and belongs to the technical field of gas separation. The deep eutectic solvent modified porous organic cage material provided by the invention is characterized by comprising a porous organic cage material and a deep eutectic solvent loaded on the surface and in a cavity of the porous organic cage material, the deep eutectic solvent is a choline deep eutectic solvent. According to the method, the deep eutectic solvent is introduced into a cavity of the POCs material, groups such as hydroxyl of the deep eutectic solvent can generate hydrogen bonds with C-N and C = N of POCs and a polymer matrix membrane, the problem that the cavity of the POCs material is too large can be effectively solved, and CO2 gas separation selectivity is improved; and the interface compatibility between the polymer-based membrane and the POCs material can be improved by a deep eutectic solvent, so that a continuous gas transmission channel is formed, and the advantages of high selectivity and permeability are achieved.

Description

Technical Field

[0001] This invention belongs to the field of gas separation technology, specifically relating to a deep eutectic solvent-modified porous organic cage material, a mixed matrix membrane, its preparation method, and its application. Background Art

[0002] To mitigate climate change and air pollution caused by the overuse of fossil fuels, CO2 capture technology has received widespread attention and development. Porous organic cages (POCs) have emerged as a promising class, composed of individually designed macromolecules with inherent cavities that are customizable, soluble, easily regenerable, and suitable for precise modification. Similar to mature porous framework materials such as zeolites, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs), POCs have demonstrated inherent potential in gas separation applications in recent years. Furthermore, POCs possess discrete molecular structures and exhibit good to excellent solubility in common solvents, making their solution dispersibility and processability readily achieved within mature, insoluble, and extended porous frameworks. However, POCs are discrete molecules bound together by weak intermolecular interactions, resulting in pores originating not only from intrinsic cavities but also from exogenous voids or channels caused by inefficient stacking of solid molecules. The cavities in POC materials are typically large (e.g., the average pore size of CC3 is 5.33 nm), which is too large for CO2 separation, leading to poor CO2 selectivity and resulting in poor sieving performance. Summary of the Invention

[0003] The purpose of this invention is to provide a deep eutectic solvent-modified porous organic cage material, a mixed matrix membrane, its preparation method and application. The deep eutectic solvent-modified porous organic cage material prepared by this invention has a smaller nanopore size and higher separation selectivity for CO2.

[0004] To achieve the objectives of this invention, the following technical solutions are provided:

[0005] A deep eutectic solvent-modified porous organic cage material, comprising a porous organic cage material and a deep eutectic solvent loaded on the surface and in the cavity of the porous organic cage material;

[0006] The deep eutectic solvent is a choline-based deep eutectic solvent.

[0007] Preferably, the hydrogen bond acceptors of the choline-based deep eutectic solvent include one or more of choline chloride, choline hydroxide, and polyethylene glycol;

[0008] Hydrogen bond donors include one or more of urea, glycerol, ethylene glycol, and amino acids.

[0009] Preferably, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 5.

[0010] Preferably, the porous organic cage is one or more of CC3, R-CC3, CC2, CC1, CC5 and CC9.

[0011] Preferably, the mass ratio of the deep eutectic solvent to the porous organic cage material is 5 to 1:1.

[0012] This invention also provides a method for preparing the deep eutectic solvent-modified porous organic cage material described in the above technical solution, comprising the following steps:

[0013] The porous organic cage and the deep eutectic solvent are mixed and dried to obtain the deep eutectic solvent modified porous organic cage material.

[0014] Preferably, the mixing is carried out in an organic solvent; the organic solvent includes one or more of alcohols, halogenated hydrocarbons, and amides.

[0015] The present invention also provides a hybrid matrix membrane, comprising a polymer base membrane and a deep eutectic solvent-modified porous organic cage material dispersed in the polymer base membrane as described in the above technical solution or a deep eutectic solvent-modified porous organic cage material prepared by the preparation method described in the above technical solution;

[0016] The polymer-based film is a nylon elastomer;

[0017] The mass ratio of the deep eutectic solvent-modified porous organic cage material to the polymer base film is 1:1 to 10.

[0018] The present invention also provides the application of the deep eutectic solvent-modified porous organic cage material or the mixed matrix membrane described in the above technical solutions in gas storage adsorbents, gas separation membranes or as CO2 hydrogenation catalysts.

[0019] Preferably, the application is in the use of gas storage adsorbents and separation membranes for CO2 and N2, and in the use of storage adsorbents and separation membranes for CO2 and CH4.

[0020] This invention provides a deep eutectic solvent-modified porous organic cage material, comprising a porous organic cage material and a deep eutectic solvent loaded on the surface and within the cavities of the porous organic cage material; the deep eutectic solvent is a choline-based deep eutectic solvent. The pore size of POCs materials is too large for CO2 separation, resulting in poor sieving efficiency. This invention introduces a deep eutectic solvent (DES) into the cavities of the POCs material, causing the POCs to recrystallize or rearrange, forming POCs encapsulated by the deep eutectic solvent. The hydroxyl and other groups in the deep eutectic solvent can form hydrogen bonds with the CN and C=N groups of the POCs. The deep eutectic solvent fills the cavities of the POCs, reducing the pore size to between that of CO2 and N2, effectively improving the problem of excessively large pore size and enhancing the selectivity of CO2 gas separation. Furthermore, the deep eutectic solvent has an affinity for CO2, increasing the CO2 diffusion coefficient and allowing a large amount of CO2 to permeate, thus increasing the membrane permeability and further improving the CO2 gas separation effect. Furthermore, the deep eutectic solvent-modified POCs material provided by this invention has sub-nanometer or even nanometer-scale windows, which can sieve gases with equivalent diameters in the nanometer range.

[0021] The present invention also provides a hybrid matrix membrane, comprising a polymer base membrane and a deep eutectic solvent-modified porous organic cage material dispersed in the polymer base membrane. In the prior art, the inorganic filler has poor interfacial compatibility with the organic polymer, resulting in reduced separation efficiency. In the present invention, the deep eutectic solvent can simultaneously generate highly reversible hydrogen bonding between the hydrogen bonding sites of POCs and the polymer base membrane, thereby improving the interfacial compatibility between the polymer base membrane and the POCs material, thus forming a continuous gas transport channel with the advantages of high selectivity and permeability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a scanning electron microscope image of CC3, a pure POCs material from Example 1 of the present invention.

[0024] Figure 2 This is a scanning electron microscope image of the DES@CC3-30wt% material obtained in Example 1 of the present invention;

[0025] Figure 3 The gas separation results of the DES@CC3 / pebax1657 membranes obtained in Examples 1, 3-5 and Comparative Example 1 of this invention;

[0026] Figure 4The results show the long-term stability test results of gas separation of the DES@CC3 / pebax1657 membrane obtained in Example 1 of this invention. Detailed Implementation

[0027] This invention provides a deep eutectic solvent-modified porous organic cage material, characterized in that it comprises a porous organic cage material and a deep eutectic solvent loaded on the surface and in the cavity of the porous organic cage material;

[0028] The deep eutectic solvent is a choline-based deep eutectic solvent.

[0029] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0030] In this invention, the porous organic cages (POCs) include one or more of CC3, R-CC3, CC2, CC1, CC5, and CC9. In a specific embodiment, it can be CC3. The CC3 is a covalent cage 3. This invention can adopt the CC3 disclosed in the literature "Recent advances in the applications of porous organic cages, Dingyue Hu, Jinjin Zhang and Ming Liu, Supplementary information". The POCs material powder includes imine bonds formed by the dehydration condensation of aldehydes and amines, which constitute POCs. For example, CC3 has an octahedral spatial configuration.

[0031] In this invention, the deep eutectic solvent is a choline-based deep eutectic solvent; the hydrogen bond acceptor of the choline-based deep eutectic solvent includes one or more of choline chloride, choline hydroxide, and polyethylene glycol; the hydrogen bond donor includes one or more of urea, glycerol, ethylene glycol, and amino acids; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 5. In specific embodiments, it can be choline chloride and glycerol with a molar ratio of 1:2 (ChCl:glyc 1:2), choline chloride and ethylene glycol with a molar ratio of 1:4 (ChCl:EG 1:4), polyethylene glycol with a molar ratio of 1:2, choline hydroxide, and L-proline.

[0032] In this invention, the mass ratio of the deep eutectic solvent to the porous organic cage material is 5 to 1:1. In specific embodiments, it can be 2:1, 3:1 or 4:1.

[0033] In this invention, the average pore size of the deep eutectic solvent-modified porous organic cage material is 2.8–4.5 nm, and in a specific embodiment, it can be 3.62 nm.

[0034] This invention also provides a method for preparing the deep eutectic solvent-modified porous organic cage material described in the above technical solution, comprising the following steps:

[0035] The porous organic cage and the deep eutectic solvent are mixed and dried to obtain the deep eutectic solvent modified porous organic cage material.

[0036] In this invention, the mixing is carried out in an organic solvent; the organic solvent includes one or more of alcohols, halogenated hydrocarbons, and amides; the alcohol is methanol or ethanol, the halogenated hydrocarbon is dichloromethane, and the amide is N,N-dimethylformamide; in a specific embodiment, the organic solvent can be ethanol, a mixture of ethanol and dichloromethane in a mass ratio of 95:5, or a mixture of methanol and dichloromethane in a mass ratio of 95:5.

[0037] In this invention, the proportion of the porous organic cage in the total mass of the deep eutectic solvent and the organic solvent is greater than 0 and less than or equal to 30 wt%.

[0038] In this invention, the mixing is carried out under stirring conditions for 1 to 4 hours, which can be 2 or 3 hours in a specific embodiment, and the temperature is 10 to 35°C, which can be 20 or 25°C in a specific embodiment.

[0039] The present invention does not specifically limit the stirring rate; in a specific embodiment, it can be 200–300 rpm. In the present invention, the drying temperature is 60–80°C; in a specific embodiment, it can be 65 or 70°C; the drying time is 8–24 hours; in a specific embodiment, it can be 12 or 18 hours; the drying is vacuum drying.

[0040] In this invention, the process before drying also includes washing; the reagent used for washing is ethanol, and the washing is performed 1 to 5 times.

[0041] This invention also provides a deep eutectic solvent-modified porous organic cage material prepared by the preparation method described above. The deep eutectic solvent-modified porous organic cage material has sub-nanoscale and / or nanoscale windows, as well as nanoscale cavities. In this invention, the sub-nanoscale and / or nanoscale windows can sieve ions of different sizes, and the nanoscale cavities provide a faster transport path for small ions. Furthermore, it can improve the poor compatibility between the original CC3 and polymer matrix interface, thereby forming a continuous gas transport channel and achieving the advantages of high selectivity and permeability.

[0042] The present invention also provides a hybrid matrix membrane, comprising a polymer base membrane and a deep eutectic solvent-modified porous organic cage material as described in the above-mentioned technical solution dispersed in the polymer base membrane; wherein the polymer base membrane is a nylon elastomer;

[0043] The mass ratio of the deep eutectic solvent-modified porous organic cage material to the polymer base film is 1:1 to 10.

[0044] In this invention, the polymer base film is a nylon elastomer (Pebax-MMMs), and in a specific embodiment, it can be Pebax1657; the mass ratio of the deep eutectic solvent-modified porous organic cage material to the polymer base film is 1:1 to 10, and in a specific embodiment, it can be 1:2, 1:3, 1:6 or 1:8.

[0045] In this invention, the method for preparing the hybrid matrix membrane includes the following steps:

[0046] The polymer-based membrane is dissolved in an organic solvent to obtain a polymer-based membrane solution;

[0047] The polymer-based film solution and the deep eutectic solvent-modified porous organic cage material are mixed to obtain the casting solution;

[0048] The casting solution is coated onto the substrate and dried to obtain the mixed matrix membrane.

[0049] In this invention, the organic solvent is an alcohol-water mixed solvent, and in a specific embodiment, it can be ethanol-water. The mass ratio of ethanol to water is 5-7:3-5; the dissolution temperature is 80-100°C, and in a specific embodiment, it can be 90°C; the dissolution is carried out under stirring conditions, the stirring rate is 200-500 rpm, and in a specific embodiment, it can be 300 or 400 rpm; the time is 12-24 hours.

[0050] In this invention, the polymer-based film solution and the ionic liquid-modified porous organic cage material are mixed for 2 to 4 hours; the invention also includes allowing the resulting mixture to stand to obtain a casting solution; the standing temperature is 60 to 80°C and the time is 2 to 4 hours.

[0051] In this invention, the drying process is the same as described above, and will not be repeated here.

[0052] The present invention also provides the application of the deep eutectic solvent-modified porous organic cage material or the mixed matrix membrane described in the above technical solutions in gas storage adsorbents, gas separation membranes or as CO2 hydrogenation catalysts.

[0053] In this invention, the application is in the use of gas storage adsorbents and separation membranes for CO2 and N2, and in the use of storage adsorbents and separation membranes for CO2 and CH4.

[0054] To further illustrate the present invention, the following detailed description, in conjunction with the accompanying drawings and embodiments, describes the deep eutectic solvent-modified porous organic cage material, the mixed matrix membrane, its preparation method, and its application provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0055] Example 1

[0056] 1.17 g of Chcl:EG (molar ratio 1:4) and 0.5 g of CC3 powder were mixed in a beaker. At room temperature, the homogeneous DES@CC3 powder was transferred to a mortar, and 20 mL of ethanol was added. The mixture was stirred thoroughly for 3 hours. The solution was centrifuged, washed 1–3 times with ethanol, and vacuum dried at 80 °C for 12 hours. After complete evaporation of the solvent, the material was removed, yielding the DES@CC3 material, denoted as DES@CC3-30wt%.

[0057] Weigh 0.6 g of Pebax1657 and place it in a mixture of 19.4 g of anhydrous ethanol (anhydrous ethanol: deionized water = 7:3). Stir at 80 °C and 300 rpm for 2 h. Add 0.0315 g of the above DES@CC3 sample and continue stirring for 3 h. Let the resulting solution stand at 60 °C for 2 h. Then, slowly spread it on a smooth petri dish and evaporate it at room temperature for 24 h. Vacuum dry at 40 °C for 24 h to remove excess solvent, and obtain a DES@CC3 / Pebax1657 mixed matrix membrane doped with 5 wt% DES@CC3.

[0058] Example 2

[0059] 1 g of Chcl:glyc (molar ratio 1:2) and 0.5 g of CC3 powder were mixed in a beaker. At 30°C, the well-mixed DES@CC3 powder was transferred to a mortar, and 20 mL of ethanol was added. The mixture was stirred thoroughly for 3 hours. The solution was centrifuged, washed 1–3 times with ethanol, and vacuum dried at 80°C for 12 hours. After complete evaporation of the solvent, the material was removed, yielding the DES@CC3 material, denoted as DES@CC3-33wt%.

[0060] Weigh 0.6 g of Pebax1657 and place it in a mixture of 19.4 g of anhydrous ethanol (anhydrous ethanol: deionized water = 7:3). Stir at 80 °C and 300 rpm for 2 h. Add 0.0315 g of the above DES@CC3 sample and continue stirring for 3 h. Let the resulting solution stand at 60 °C for 2 h. Then, slowly spread it on a smooth petri dish and evaporate it at room temperature for 24 h. Vacuum dry at 40 °C for 24 h to remove excess solvent, and obtain a DES@CC3 / Pebax1657 mixed matrix membrane doped with 5 wt% DES@CC3.

[0061] Example 3

[0062] The DES@CC3 / Pebax1657 mixed matrix membrane was prepared according to the preparation method described in Example 1, except that the amount of Chcl:EG was 2g, resulting in DES@CC3-20wt%.

[0063] Example 4

[0064] A DES@CC3 / Pebax1657 mixed matrix membrane was prepared according to the preparation method described in Example 1, except that the amount of Chcl:EG was 0.75g, resulting in DES@CC3-40wt%.

[0065] Example 5

[0066] A DES@CC3 / Pebax1657 mixed matrix membrane was prepared according to the preparation method described in Example 1, except that the amount of Chcl:EG was 0.5g, resulting in DES@CC3-50wt%.

[0067] Comparative Example 1

[0068] A DES@CC3 / Pebax1657 mixed matrix membrane was prepared according to the preparation method described in Example 1, except that the amount of Chcl:EG was 0.33g, resulting in DES@CC3-60wt%.

[0069] Test Example 1

[0070] Figure 1 This is a scanning electron microscope image of the pure POCs material CC3 in Example 1 of the present invention; Figure 2 The image shows a scanning electron microscope (SEM) image of the DES@CC3-30wt% material obtained in Example 1 of this invention. As can be seen from the image, the deep eutectic solvent encapsulates CC3.

[0071] Table 1 shows the pore size information of DES@CC3-30wt% obtained from CC3 and Example 1.

[0072]

[0073] As shown in Table 1, the DES@CC3-30wt% material prepared in Example 1 of this invention has a smaller average pore size (3.62nm) compared with pure POCs, which plays a dominant role in improving gas separation selectivity.

[0074] Figure 3The gas separation results of the DES@CC3 / pebax1657 membranes obtained in Examples 1, 3-5 and Comparative Example 1 of this invention are shown. By comparing with pure pebax-based membranes and pure CC3 materials, it can be seen that the deep eutectic solvent-modified CC3 proposed in this invention can improve the permeability and selectivity of the gas separation membrane to a certain extent. This invention not only provides CO2 with affinity sites to form continuous transport channels, thereby increasing its permeation, but also improves the pore size of CC3, making its pore size smaller, which is not conducive to N2 permeation, thereby improving CO2 selectivity.

[0075] Figure 4 For the long-term stability test of gas separation of the DES@CC3 / pebax1657 membrane obtained in Example 1 of this invention, there are... Figure 4 It can be seen that its performance is stable within 30 hours; and combined with Figure 3 As a result, although the separation performance was slightly reduced due to plasticization caused by the long-term testing of the membrane within 40-70 hours, it was still better than the separation performance of the pure CC3 material before modification.

[0076] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A deep eutectic solvent-modified porous organic cage material, characterized in that, Includes a porous organic cage material and a deep eutectic solvent loaded on the surface and within the cavities of the porous organic cage material; The deep eutectic solvent is a choline-based deep eutectic solvent.

2. The deep eutectic solvent-modified porous organic cage material according to claim 1, characterized in that, The hydrogen bond acceptors of the choline-based deep eutectic solvent include one or more of choline chloride, choline hydroxide, and polyethylene glycol. Hydrogen bond donors include one or more of urea, glycerol, ethylene glycol, and amino acids.

3. The deep eutectic solvent-modified porous organic cage material according to claim 2, characterized in that, The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 5.

4. The deep eutectic solvent-modified porous organic cage material according to claim 1, characterized in that, The porous organic cage is one or more of CC3, R-CC3, CC2, CC1, CC5 and CC9.

5. The deep eutectic solvent-modified porous organic cage material according to any one of claims 1 to 4, characterized in that, The mass ratio of the deep eutectic solvent to the porous organic cage material is 5 to 1:

1.

6. The method for preparing the deep eutectic solvent-modified porous organic cage material according to any one of claims 1 to 5, characterized in that, Includes the following steps: The porous organic cage and the deep eutectic solvent are mixed and dried to obtain the deep eutectic solvent modified porous organic cage material.

7. The preparation method according to claim 6, characterized in that, The mixing is carried out in an organic solvent; the organic solvent includes one or more of alcohols, halogenated hydrocarbons, and amides.

8. A hybrid matrix membrane, characterized in that, The material includes a polymer-based membrane and a deep eutectic solvent-modified porous organic cage material as described in any one of claims 1 to 5 dispersed in the polymer-based membrane, or a deep eutectic solvent-modified porous organic cage material prepared by the preparation method described in claims 6 and 7. The polymer-based film is a nylon elastomer; The mass ratio of the deep eutectic solvent-modified porous organic cage material to the polymer base film is 1:1 to 10.

9. The use of the deep eutectic solvent-modified porous organic cage material according to any one of claims 1 to 5 or the mixed matrix membrane according to claim 8 in gas storage adsorbents, gas separation membranes or as CO2 hydrogenation catalysts.

10. The application according to claim 9, characterized in that, The application is in the use of gas storage adsorbents and separation membranes for CO2 and N2, and in the use of storage adsorbents and separation membranes for CO2 and CH4.

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