Mixed matrix membranes with high loading of two-dimensional metal-organic framework nus-8 and methods of making and using the same
A hybrid matrix membrane with high two-dimensional metal-organic framework (MOR) NUS-8 packing content was prepared by in-situ crystallization and spin coating, which solved the problem of insufficient packing content in the prior art, achieved high efficiency CO2/N2 separation performance, simplified the preparation process and improved the stability of the membrane.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2023-12-27
- Publication Date
- 2026-07-07
Smart Images
Figure CN117531384B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a hybrid matrix membrane with a high two-dimensional metal-organic framework NUS-8 filling content, belonging to the field of composite membrane technology. Background Technology
[0002] Highly efficient and energy-saving carbon capture technology is one of the most important and difficult challenges in the chemical industry.
[0003] Currently, carbon capture separation processes primarily rely on energy-intensive, heat-driven cryogenic distillation. Membrane separation is an emerging technology that, due to its mild operating conditions, continuous operation, and highly integrated equipment, has the potential to save up to 90% of energy and significant equipment investment. Traditional polymer membranes are limited by the trade-off effect and are prone to aging and plasticization. Hybrid matrix membranes, combining the advantages of easy polymer film formation and the molecular sieving properties of porous fillers, have become a research hotspot. Two-dimensional metal-organic frameworks (MOFs) are considered the most ideal filling materials for hybrid matrix membranes, attracting extensive research. However, hybrid matrix membranes with high MOF loading remain a significant challenge, limiting the performance of carbon capture membranes and hindering their practical application. Therefore, developing a simple and effective method for preparing hybrid matrix membranes with high MOF NUS-8 loading is expected to further advance the application of hybrid matrix membranes in the field of carbon capture. Summary of the Invention
[0004] To address the aforementioned limitations of existing technologies, this invention proposes a hybrid matrix membrane with a high content of two-dimensional metal-organic framework (NUS-8), prepared using in-situ crystallization and spin-coating methods. The process includes: in-situ crystallization and cross-linking of the two-dimensional NUS-8 framework in a PEI polymer phase to form two-dimensional PEI-NUS-8 composite nanosheets; spin-coating the two-dimensional PEI-NUS-8 composite nanosheets onto a polymer substrate to obtain the hybrid matrix membrane; the thickness of the hybrid matrix membrane is 40-120 nm; and the weight percentage of the two-dimensional NUS-8 framework in the hybrid matrix membrane is 85%. The preparation method of this hybrid matrix membrane is simple and controllable, and the specific steps are as follows:
[0005] Step 1: Using 1,3,5-benzenetricarboxylic acid, ZrCl4 and polyethyleneimine as reactants, two-dimensional polymeric PEI-metal-organic framework NUS-8 composite nanosheets were prepared by in-situ crystallization, denoted as PEI-NUS nanosheets.
[0006] Step 2: Using the PEI-NUS nanosheets, PEI-NUS nanosheets are deposited on a PAN polymer substrate by spin coating. After drying, a hybrid matrix film filled with a two-dimensional metal-organic framework (NUS-8) is obtained, denoted as PEI / NUS-M. The filling amount of the two-dimensional metal-organic framework NUS-8 in this hybrid matrix film is 85% by weight.
[0007] Furthermore, in the preparation method described in this invention, wherein:
[0008] The specific content of step 1 is as follows:
[0009] Step 1-1) Dissolve 1,3,5-benzenetricarboxylic acid and ZrCl4 powder in dimethylformamide solvent to form a mixed solution. In this mixed solution, the mass-to-volume ratio of 1,3,5-benzenetricarboxylic acid is 2 mg / mL, and the mass-to-volume ratio of ZrCl4 is 1.5 mg / mL. Add formic acid to the above mixed solution at a volume ratio of 15:100 to form solution A.
[0010] Polyethyleneimine is dissolved in dimethylformamide to form solution B. In solution B, the mass ratio of polyethyleneimine to 1,3,5-benzenetricarboxylic acid in solution A is 1:2, and the volume ratio of dimethylformamide to solution A is 15:100.
[0011] Solution A and solution B were mixed and sealed, and heated at 120°C for 24 hours to obtain a colloidal suspension.
[0012] Step 1-2) The colloidal suspension was centrifuged at 8000 rpm for 5 minutes to obtain the colloidal precipitate of the PEI-NUS nanosheets, which was then dispersed in fresh dimethylformamide solvent. This step 1-2) was repeated three times.
[0013] Steps 1-3) Soak the PEI-NUS nanosheets obtained in Step 1-2) in fresh dimethylformamide solvent for 24 hours, collect the PEI-NUS nanosheets precipitate, wash it 3 times with methanol, and then disperse it in fresh methanol to obtain a PEI-NUS nanosheet solution with a concentration of 1.5 mg / mL.
[0014] Step 2 involves diluting the PEI-NUS nanosheet solution obtained in Step 1 with twice the volume of deionized water to prepare the casting solution; using polyacrylonitrile as the substrate; and taking a relative substrate area of 0.06-0.25 mg / cm². 2 The casting solution was spin-coated onto the surface of a polyacrylonitrile substrate and then dried at room temperature to obtain PEI / NUS-M with a film thickness of 40~120 nm.
[0015] The advantages of this invention are: the preparation process of the hybrid matrix membrane is simple, highly controllable, uses readily available raw materials, and has strong versatility. The hybrid matrix membrane prepared by this invention has a two-dimensional metal-organic framework (NUS-8) packing content of 85 wt%. When the hybrid matrix membrane prepared by the method of this invention is used for CO2 / N2 system separation, under the conditions of 25°C, feed gas pressure of 1 bar, and relative humidity of 100%, the CO2 permeation rate is 460~900 GPU, and the CO2 / N2 selectivity is 25~72. Attached Figure Description
[0016] Figure 1 This is a cross-sectional electron microscope image of membrane 1 prepared in Example 1;
[0017] Figure 2 This is a cross-sectional electron microscope image of membrane 2 prepared in Example 2;
[0018] Figure 3 This is a cross-sectional electron microscope image of membrane 3 prepared in Example 3;
[0019] Figure 4 This is a cross-sectional electron microscope image of membrane 4 prepared in Example 4;
[0020] Figure 5 This is a comparison chart of CO2 permeation rate and CO2 / N2 selectivity performance of membranes 1-4. Detailed Implementation
[0021] This invention provides a hybrid matrix membrane with a high NUS-8 (two-dimensional metal-organic framework) loading. The design concept involves synthesizing NUS-8 in a PEI (polyethylene terephthalate) polymer phase via in-situ crystallization, forming a PEI-NUS-8 composite nanosheet. This composite nanosheet is then deposited onto a PAN (polyethylene terephthalate) polymer substrate using spin-coating to obtain a hybrid matrix membrane with a thickness of 40-120 nm and a NUS-8 loading of 85 wt%. The preparation method is simple and controllable, and the resulting hybrid matrix membrane exhibits excellent CO2 / N2 separation performance and operational stability when used for CO2 / N2 system separation.
[0022] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and appendices. The specific embodiments described are only for explanation and illustration of the present invention and are not intended to limit the present invention.
[0023] Example 1: Preparation of a hybrid matrix membrane with a high two-dimensional metal-organic framework NUS-8 filling amount, the steps are as follows:
[0024] Step 1: Using 1,3,5-benzenetricarboxylic acid, ZrCl4 and polyethyleneimine (PEI) as reactants, two-dimensional polymeric PEI-metal-organic framework (NUS-8) composite nanosheets, denoted as PEI-NUS, were prepared by in-situ crystallization.
[0025] 1,3,5-Benzotricarboxylic acid and ZrCl4 powder were dissolved in dimethylformamide to form a mixed solution containing 2 mg / mL 1,3,5-Benzotricarboxylic acid and 1.5 mg / mL ZrCl4. Then, formic acid was added at a volume percentage of 15% to form solution A. Polyethyleneimine (PEI) at a mass ratio of 0.5 to 1,3,5-Benzotricarboxylic acid was dissolved in dimethylformamide at a volume percentage of 15% to form solution A to form solution B. Solutions A and B were mixed, and the sealed mixture was heated at 120°C for 24 hours.
[0026] The obtained colloidal suspension was centrifuged at 8000 rpm for 5 minutes to obtain a PEI-NUS nanosheet colloidal precipitate, which was dispersed in fresh dimethylformamide solvent. This process was repeated three times. After the last precipitate was soaked in fresh DMF for 24 hours, the collected PEI-NUS nanosheet colloidal precipitate was washed three times with methanol and then dispersed in fresh methanol. The concentration of PEI-NUS nanosheets was determined to be 1.5 mg / mL by solvent evaporation.
[0027] Step 2: The PEI-NUS nanosheets are deposited on a PAN polymer substrate by spin coating and dried to obtain a mixed matrix film with a high two-dimensional metal-organic framework NUS-8 filling amount, denoted as PEI / NUS-M.
[0028] The PEI-NUS nanosheet solution was diluted with twice the volume of deionized water to prepare the casting solution; PAN polymer was used as the substrate; the relative area of the PAN polymer substrate was 0.06 mg / cm². 2 The casting solution was spin-coated onto the surface of the PAN polymer substrate and then dried at room temperature; Figure 1 As shown, a hybrid matrix film with a thickness of approximately 40 nm was finally obtained, denoted as film 1.
[0029] Inductively coupled plasma atomic emission spectrometry (ICP-AES) revealed that the amount of two-dimensional metal-organic framework NUS-8 in the hybrid matrix membrane was 85 wt%.
[0030] Membrane 1 was used for CO2 / N2 separation. Under the conditions of 25°C, feed gas pressure of 1 bar, and relative humidity of 100%, the CO2 permeation rate was 900 GPU and the CO2 / N2 selectivity was 25.
[0031] Example 2: Preparation of a hybrid matrix membrane with high two-dimensional metal-organic framework NUS-8 filling content. The preparation steps are basically the same as in Example 1, except that in step two, the mass of PEI-NUS nanosheets deposited on the PAN polymer substrate by spin coating is increased from 0.06 mg / cm³. 2 Change to 0.1 mg / cm 2 ,like Figure 2 As shown, a hybrid matrix membrane with a thickness of approximately 60 nm and a two-dimensional metal-organic framework NUS-8 filling amount of 85 wt% was finally obtained, denoted as membrane 2.
[0032] Membrane 2 was used for CO2 / N2 separation. Under the conditions of 25°C, feed gas pressure of 1 bar, and relative humidity of 100%, the CO2 permeation rate was 750 GPU and the CO2 / N2 selectivity was 50.
[0033] Example 3: Preparation of a hybrid matrix membrane with high two-dimensional metal-organic framework NUS-8 filling content. The preparation steps are basically the same as in Example 1, except that in step two, the mass of PEI-NUS nanosheets deposited on the PAN polymer substrate by spin coating is increased from 0.06 mg / cm³. 2 Change to 0.15 mg / cm 2 ,like Figure 3 As shown, a hybrid matrix membrane with a thickness of approximately 85 nm and a two-dimensional metal-organic framework NUS-8 filling amount of 85 wt% was finally obtained, denoted as membrane 3.
[0034] Membrane 3 was used for CO2 / N2 separation. Under the conditions of 25°C, feed gas pressure of 1 bar, and relative humidity of 100%, the CO2 permeation rate was 590 GPU and the CO2 / N2 selectivity was 65.
[0035] Example 4: Preparation of a hybrid matrix membrane with high two-dimensional metal-organic framework NUS-8 filling content. The preparation steps are basically the same as in Example 1, except that in step two, the mass of PEI-NUS nanosheets deposited on the PAN polymer substrate by spin coating is increased from 0.06 mg / cm³. 2 Change to 0.25 mg / cm 2 ,like Figure 4 As shown, a hybrid matrix membrane with a thickness of approximately 120 nm and a two-dimensional metal-organic framework NUS-8 filling amount of 85 wt% was finally obtained, denoted as membrane 3.
[0036] Membrane 4 was used for CO2 / N2 separation. Under the conditions of 25°C, feed gas pressure of 1 bar, and relative humidity of 100%, the CO2 permeation rate was 460 GPU and the CO2 / N2 selectivity was 72.
[0037] Table 1. Membrane thickness, casting solution dosage, and membrane separation performance of membranes 1-4
[0038]
[0039] As shown in Table 1 and Figure 5 As shown in the comparison of Examples 1-4, it is evident that the addition of PEI-NUS composite nanosheets in step two significantly contributes to the improvement of the separation performance of the mixed matrix membrane (such as CO2 permeation rate and CO2 / N2 selectivity). By varying the amount of PEI-NUS composite nanosheets used in step two, the CO2 permeation rate can reach 460-900 GPU, and the CO2 / N2 selectivity is 25-72, with the amount of PEI-NUS composite nanosheets used being 0.15 mg / cm³. 2 At that time, the CO2 / N2 separation performance reached its highest level, with a CO2 permeation rate of 590 GPUs and a CO2 / N2 selectivity of 65.
[0040] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit of the present invention, and these modifications are all within the protection scope of the present invention.
Claims
1. A hybrid matrix membrane with a high two-dimensional metal-organic framework (NUS-8) filling content, characterized in that, The method involves in-situ crystallization and spin-coating, comprising: in-situ crystallization and cross-linking of two-dimensional metal-organic framework NUS-8 in a polymeric PEI phase to form two-dimensional polymeric PEI-metal-organic framework NUS-8 composite nanosheets; spin-coating the two-dimensional polymeric PEI-metal-organic framework NUS-8 composite nanosheets onto a polymer substrate to obtain a mixed matrix film; the thickness of the mixed matrix film is 40~120 nm; and the filling amount of two-dimensional metal-organic framework NUS-8 in the mixed matrix film is 85% by weight.
2. A method for preparing a hybrid matrix membrane with a high two-dimensional metal-organic framework (NUS-8) filling amount as described in claim 1, characterized in that, Includes the following steps: Step 1: Using 1,3,5-benzenetricarboxylic acid, ZrCl4 and polyethyleneimine as reactants, two-dimensional polymeric PEI-metal-organic framework NUS-8 composite nanosheets were prepared by in-situ crystallization, denoted as PEI-NUS nanosheets. Step 2: PEI-NUS nanosheets are deposited on a PAN polymer substrate by spin coating. After drying, a hybrid matrix film filled with two-dimensional metal-organic framework NUS-8 is obtained, denoted as PEI / NUS-M. By weight percentage, the filling amount of two-dimensional metal-organic framework NUS-8 in the hybrid matrix film is 85%.
3. The preparation method according to claim 2, characterized in that: The specific content of step 1 is as follows: Step 1-1) Dissolve 1,3,5-benzenetricarboxylic acid and ZrCl4 powder in dimethylformamide solvent to form a mixed solution. In this mixed solution, the mass-to-volume ratio of 1,3,5-benzenetricarboxylic acid is 2 mg / mL, and the mass-to-volume ratio of ZrCl4 is 1.5 mg / mL. Add formic acid to the above mixed solution at a volume ratio of 15:100 to form solution A. Polyethyleneimine is dissolved in dimethylformamide to form solution B. In solution B, the mass ratio of polyethyleneimine to 1,3,5-benzenetricarboxylic acid in solution A is 1:2, and the volume ratio of dimethylformamide to solution A is 15:
100. Solution A and solution B were mixed and sealed, and heated at 120°C for 24 hours to obtain a colloidal suspension. Step 1-2) The colloidal suspension was centrifuged at 8000 rpm for 5 minutes to obtain the colloidal precipitate of the PEI-NUS nanosheets, which was then dispersed in fresh dimethylformamide solvent. This step 1-2) was repeated three times. Steps 1-3) Soak the colloidal precipitate of PEI-NUS nanosheets obtained in Step 1-2) in fresh dimethylformamide solvent for 24 hours, collect the colloidal precipitate of PEI-NUS nanosheets, wash it 3 times with methanol, and then disperse it in fresh methanol to obtain a PEI-NUS nanosheet solution.
4. The preparation method according to claim 3, characterized in that, In the PEI-NUS nanosheet solution obtained in steps 1-3), the concentration of PEI-NUS nanosheets is 1.5 mg / mL.
5. The preparation method according to claim 2, characterized in that: Step 2 involves diluting the PEI-NUS nanosheet solution obtained in Step 1 with twice the volume of deionized water to prepare the casting solution; using polyacrylonitrile as the substrate; and taking a relative substrate area of 0.06-0.25 mg / cm². 2 The casting solution was spin-coated onto the surface of a polyacrylonitrile substrate and then dried at room temperature to obtain PEI / NUS-M with a film thickness of 40~120 nm.
6. An application of a hybrid matrix membrane with a high two-dimensional metal-organic framework (NUS-8) filling content prepared by any one of claims 2-5, characterized in that, When the hybrid matrix membrane was used for CO2 / N2 separation, under the conditions of 25°C, feed gas pressure of 1 bar, and relative humidity of 100%, the CO2 permeation rate was 460~900 GPU and the CO2 / N2 selectivity was 25~72.