Dipeptide metal coordination network porous crystal composite membrane as well as preparation method and application thereof
By combining the self-assembled dipeptide metal coordination network membrane with amino functionalized AAO membrane, the permeability and selectivity trade-offs of traditional polymer membranes in CO2/N2 separation are solved, and efficient and stable CO2/N2 separation effect is achieved.
Patent Information
- Application Number
- CN202510673406.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-07-25
Smart Images
Figure CN120361740A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a dipeptide metal coordination network porous crystal composite membrane, a preparation method thereof and an application thereof, and belongs to the field of porous crystal composite membranes. Background Art
[0002] Carbon dioxide emissions from fossil fuel power plants have been a major problem for global warming and climate change. Separating carbon dioxide from post-combustion flue gas may help effectively remove this greenhouse gas, which poses scientific challenges due to the high similarity in physical properties and molecular sizes between CO2 / N2. Membrane separation technology is a second-generation new separation technology. Compared with the market-dominant distillation separation method, chemical absorption method and physical absorption method, membrane separation has many advantages, such as low energy consumption, high energy efficiency, strong operation feasibility and high environmental compatibility. However, for decades, there has been an inherent trade-off between permeability and selectivity in traditional polymer membrane materials, which limits the efficiency of carbon dioxide separation in the membrane separation process. Among various membrane materials, porous crystal membranes have attracted attention due to their regular and controllable pore structures. Compared with traditional porous materials, porous materials with flexible frameworks are more fascinating. However, most of the flexibility is achieved by artificial post-modification, which leads to troublesome experimental processes and uncontrollability.
[0003] Metal-peptide networks (MPNs) are assembled from peptides and metal ions and are considered to be one of the most fascinating metal-organic coordination structures due to their unique and complex structures. The short peptides used in the MPNs we selected are much more flexible than typical organic linkers and are rare natural ligands for constructing flexible porous materials. Peptides are usually composed of 2 to 50 amino acids and are linked together by peptide bonds formed through dehydration and condensation of amino and carboxyl groups. They are widely present in organisms and are indispensable functional components. The side chains of peptides have rich chemical diversity and modifiability, which can subtly regulate the flexible properties of porous crystalline membranes. By introducing functional ligands, the pore walls can be modified to achieve adjustable physical and chemical properties, thereby controlling the binding of guests to the framework as needed. However, most of the reports in current gas separation research are about post-modifying amino acids or peptides on porous crystals, and there is no application of directly using natural short peptides to form a dipeptide metal coordination network porous crystal composite membrane. Summary of the Invention
[0004] Object of the Invention: The first object of the present invention is to provide a dipeptide metal coordination network porous crystal composite membrane, which has stable performance and is green and environmentally friendly. The second object of the present invention is to provide a preparation method of the dipeptide metal coordination network porous crystal composite membrane, which is simple to operate and easy to implement under mild conditions. The third object of the present invention is to provide the application of the dipeptide metal coordination network porous crystal composite membrane in separating the mixed gas CO2 / N2. The dipeptide metal coordination network porous crystal composite membrane can be used in membrane separation technology to selectively separate CO2, and has the advantages of stable performance, high separation factor, and wide applicable environment.
[0005] Technical Solution: The dipeptide metal coordination network porous crystal composite membrane described in the present invention includes a self-assembled dipeptide metal coordination network membrane and a membrane material with a macroporous structure. Some pores in the self-assembled dipeptide metal coordination network membrane correspond to and communicate with some macropores in the membrane material with a macroporous structure.
[0006] Further, the membrane material with a macroporous structure is an amino-functionalized anodic aluminum oxide membrane (AAO).
[0007] Further, the pore diameter of the amino-functionalized anodic aluminum oxide membrane is 50 - 100 nm, preferably 70 nm.
[0008] Further, the dipeptide metal coordination network membrane is obtained by in-situ growth of coordination of a dipeptide linker with metal ions Zn 2+ on the AAO substrate.
[0009] Further, the thickness of the dipeptide metal coordination network membrane is about 200 - 220 nm, preferably 207 nm.
[0010] Further, the dipeptide linker is a bidentate dipeptide compound.
[0011] Even further, the dipeptide linker is glycyl-glycine (Gly-Gly), glycyl-alanine (Gly-Ala) or glycyl-serine (Gly-Ser), preferably glycyl-alanine.
[0012] Further, the preparation of the amino-functionalized membrane material with a macroporous structure includes the following steps:
[0013] Dilute the (3-aminopropyl)triethoxysilane (APTES) solution in ethanol, mix well, immerse the membrane material with a macroporous structure, and let it stand overnight to obtain the amino-functionalized membrane material with a macroporous structure.
[0014] Even further, the volume ratio of the APTES solution to the ethanol solution is 1:(1 - 9), preferably 1:9, and the immersion time is more than 12 h.
[0015] The preparation method of the dipeptide metal coordination network porous crystal composite membrane of the present invention includes the following steps:
[0016] (1) Dissolve the dipeptide linker in a methanol (MeOH) solvent, and perform ultrasonic treatment to obtain a uniform mixed solution;
[0017] (2) Place the amino-functionalized membrane with a macroporous structure and the mixed solution together in a reaction vessel, add a catalyst, and fix at room temperature to form the first layer of dipeptide linker membrane;
[0018] (3) Dissolve the metal compound Zn(NO3)2·6H2O in a methanol (MeOH) solvent, add it to the reaction vessel, and carry out a heating reaction to in-situ grow the dipeptide metal coordination network porous crystal composite membrane.
[0019] Further, in step (1), after the dipeptide linker is dissolved in the methanol (MeOH) solvent, the concentration of the dipeptide linker in the solution is 5-20 mmol / L, preferably 12.5 mmol / L.
[0020] Further, in step (1), the ultrasonic treatment time is 10-20 min.
[0021] Further, in step (2), the catalyst is an NaOH solution.
[0022] Further, in step (2), the concentration of the catalyst is 1 mol / L, and the mass-volume ratio of the catalyst to the mixed solution is 0.53-1.06 mg / mL, preferably 0.96 mg / mL.
[0023] Further, in step (2), the mixed solution in the reactor submerges the amino-functionalized membrane with a macroporous structure, and the fixing time at room temperature is 6-18 h, preferably 12 h.
[0024] Further, in step (3), different thicknesses of the dipeptide metal coordination network membrane can be obtained by changing the in-situ growth time.
[0025] Further, in step (3), the concentration of Zn(NO3)2 in the methanol solvent is 20-60 mmol / L, preferably 30 mmol / L.
[0026] Further, in step (3), the heating reaction temperature is 80-100 °C, and the heating reaction time is 12-24 h, preferably 85 °C, and the reaction is carried out for 18 h.
[0027] The application of the dipeptide metal coordination network porous crystal composite membrane of the present invention in gas separation.
[0028] Further, the gas contains CO2 and N2, and the volume ratio of CO2 / N2 is (1:9)-(9:1).
[0029] Furthermore, the partial pressure of CO2 gradually increases, and the performance is the best when the partial pressure of CO2 is above 0.2 MPa.
[0030] Further, during the gas separation process, the dipeptide metal coordination network porous crystal composite membrane preferentially adsorbs CO2 in the mixed gas. When the CO2 pressure reaches a certain value (above 0.2 MPa), the dipeptide metal coordination network can open the pores, and the CO2 adsorbed on the pore surface preferentially passes through the membrane, while N2 is intercepted.
[0031] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:
[0032] The dipeptide metal coordination network porous crystal composite membrane of the present invention includes a self-assembled dipeptide metal coordination network membrane. The dipeptide metal coordination network membrane has stable performance and has the advantages of low energy consumption, high energy efficiency, strong operation feasibility, and high environmental compatibility.
[0033] The application of the dipeptide metal coordination network porous crystal composite membrane of the present invention in gas separation has obvious advantages:
[0034] (1) The pore channels of the dipeptide metal coordination network porous crystal composite membrane of the present invention have polar groups (amide, carboxylate, and amine) that have strong quadrupole-dipole interactions with CO2. In the mixed gas of CO2 and N2, CO2 is preferentially adsorbed to achieve the separation of CO2 / N2.
[0035] (2) In the present invention, at different CO2 pressures, due to the flexibility of the dipeptide ligand, the pores will open at a certain pressure to achieve high permeability and high selectivity.
[0036] (3) The dipeptide metal coordination network porous crystal composite membrane of the present invention has successfully separated CO2 and N2 in gas separation. At different ratios of CO2 / N2, the maximum CO2 permeability reaches 1553 GPU, and the selectivity factor reaches 41, which far exceeds the separation requirements for economically energy-saving carbon capture in industry (CO2 permeability > 1000 GPU and CO2 / N2 selectivity > 20).
[0037] (4) The application of the dipeptide metal coordination network porous crystal composite membrane of the present invention in gas separation shows good stability. After 60 h of testing, the separation selectivity factor hardly decays, laying a solid foundation for practical applications. Description of the Drawings
[0038] Figure 1 Schematic diagram of the preparation process of the dipeptide metal coordination network porous crystal composite membrane prepared in Example 1
[0039] Figure 2 Scanning electron microscope images of the AAO membrane prepared in Example 1; among them, A is the top image of the AAO membrane, and B is the cross-sectional image of the AAO membrane;
[0040] Figure 3 XPS characterization diagrams of the porous crystal composite membrane of the dipeptide metal coordination network with successful amino modification and successful growth of Zn(GA)2 in Example 1, where A is the AAO membrane modified by APTES, and B is the porous crystal composite membrane of the dipeptide metal coordination network with in-situ growth of Zn(GA)2;
[0041] Figure 4 Scanning electron microscope images of the porous crystal composite membrane of the dipeptide metal coordination network prepared in Example 1; among them, A is the top view of the porous crystal composite membrane of the dipeptide metal coordination network, B is a more detailed view of the porous crystal composite membrane of the dipeptide metal coordination network, C is the cross-sectional view of the porous crystal composite membrane of the dipeptide metal coordination network, and D is the EDX elemental mapping of the cross-sectional part of the porous crystal composite membrane of the dipeptide metal coordination network;
[0042] Figure 5 Schematic diagram of the membrane separation process of CO2 and N2 in Example 3;
[0043] Figure 6 Gas separation performance diagrams of single-component CO2 / N2 with different thicknesses in Example 2;
[0044] Figure 7 Ideal selectivity and single-component gas permeability performance diagrams of the H2 / N2, H2 / CO2, CO2 / N2, and C2H4 / C2H6 gas pairs of the porous crystal composite membrane of the dipeptide metal coordination network in Example 3;
[0045] Figure 8 Integrated diagram of CO2 permeability, N2 permeability, and CO2 / N2 selectivity factor of the porous crystal composite membrane of the dipeptide metal coordination network prepared in Example 1 under different CO2 partial pressures;
[0046] Figure 9 CO2 permeability, N2 permeability, and CO2 / N2 selectivity factor of the porous crystal composite membrane of the dipeptide metal coordination network at different temperatures;
[0047] Figure 10 Gas separation test diagram of the porous crystal composite membrane of the dipeptide metal coordination network prepared in Example 1 within 60 h. Detailed implementation manners
[0048] The technical solutions of the present invention will be further described below with reference to the accompanying drawings.
[0049] Example 1 Preparation of the porous crystal composite membrane of the dipeptide metal coordination network
[0050] (1) Preparation of anodic aluminum oxide (AAO) membrane: First, the aluminum foil was ultrasonically cleaned with acetone and 1 mol / L KOH for 10 minutes respectively, and then rinsed with water. The first anodization was carried out with 0.3 mol / L oxalic acid as the electrolyte at a voltage of 50 V for 30 minutes. To eliminate the formed irregular oxide layer, the first anodized aluminum foil was treated with a mixed acid solution composed of 6 wt% H3PO4 and 1.8 wt% H2CrO4 at 60 °C for 40 minutes. Subsequently, the second anodization was carried out for 4 hours, and other conditions were the same as those of the first anodization. The aluminum substrate was removed with saturated SnCl2 solution. The AAO membrane was treated with 1.8 wt% H3PO4 solution for 40 minutes to remove the barrier layer. Then the prepared AAO membrane was immersed in hydrogen peroxide solution (30% H2O2) and boiled for 30 minutes, and a large number of hydroxyl groups were generated on the channel surface. Finally, the AAO membrane was soaked in water overnight and dried. The pore size of the anodic aluminum oxide membrane nanochannels can be controlled by adjusting the oxidation voltage. The AAO membrane prepared in this example was analyzed by scanning electron microscopy, and the results are as Figure 2 shown. As Figure 2 can be seen, the pore size of the obtained AAO membrane is 70 nm, and the pore distribution is uniform.
[0051] (2) Modification of AAO membrane with APTES: The AAO membrane was immersed in a 10% ethanol solution of APTES (the volume ratio of APTES solution to ethanol solution is 1:9) for more than 12 h, then rinsed with ethanol 3 times, and placed in an oven at 120 °C for 6 h to obtain the APTES-modified AAO membrane, so that AAO was successfully modified with amino groups.
[0052] XPS characterization was carried out on the AAO membrane and the APTES-modified AAO membrane (APTES / AAO), and the results are as Figure 3 shown in A. As Figure 3 can be seen from A, the APTES / AAO has a Si 2P characteristic peak, indicating that the amino group was successfully modified.
[0053] (3) Preparation of the dipeptide metal coordination network membrane: Gly-Ala (21.95 mg, 0.015 mmol) was dissolved in 4 mL of MeOH, and 360 μL of 1 M NaOH solution was added. Then, the solution was ultrasonically treated for 15 min to obtain a homogeneous mixed system. Then, the AAO membrane modified with APTES and the mixed system containing Gly-Ala (21.95 mg) were placed at the bottom of the reaction vessel and left to stand at room temperature for 12 hours to ensure the formation of the first layer of the dipeptide linker membrane was completed. Then, 66.82 g of the metal compound Zn(NO3)2·6H2O was dissolved in 11 mL of methanol solvent and added to the reaction vessel, and the reaction was heated at 85 °C for 18 h to obtain the dipeptide metal coordination network porous crystal composite membrane (Zn(GA)2 / AAO). The entire preparation process is as Figure 1 shown.
[0054] XPS characterization was performed on the in-situ grown dipeptide metal coordination network porous crystal composite membrane, and the results are as Figure 3 shown in B of Figure 3 . As can be seen from B of
[0055] , there are Zn 2P characteristic peaks, indicating the successful growth of the dipeptide metal coordination network membrane (Zn(GA)2).
[0055] Scanning electron microscopy analysis was performed on the dipeptide metal coordination network porous crystal composite membrane prepared in this example, and the results are as Figure 4 shown. Figure 4 Figure 16 is the scanning electron microscopy image of the dipeptide metal coordination network porous crystal composite membrane prepared in Example 1; among them, A is the top view of the dipeptide metal coordination network porous crystal composite membrane, B is a more detailed view of the dipeptide metal coordination network porous crystal composite membrane, C is the cross-sectional view of the dipeptide metal coordination network porous crystal composite membrane, and D is the EDX element mapping of the cross-sectional part of the dipeptide metal coordination network porous crystal composite membrane. As can be seen from Figure 3 , the thickness of the dipeptide metal coordination network membrane of the selective layer of the dipeptide metal coordination network porous crystal composite membrane obtained is 205 ± 5 nm. The dipeptide metal coordination network porous crystals closely cover the top of the AAO nanochannels, indicating the successful preparation of the dipeptide metal coordination network porous crystal composite membrane.
[0056] Preparation of the dipeptide metal coordination network membrane porous crystal composite membrane with different thicknesses in Example 2
[0057] The experimental procedure was the same as that in Example 1. Compared with Example 1, by changing the growth time of the dipeptide metal coordination network membrane in step (3) of Example 1, that is, the heating reaction time at 85 °C was 12 h and 24 h respectively, continuous MPN membranes with different thicknesses, that is, dipeptide metal coordination network porous crystal composite membranes with dipeptide metal coordination network membrane thicknesses of 100 ± 5 nm and 520 ± 50 nm respectively, could be obtained.
[0058] Example 3 Gas Separation of Dipeptide Metal Coordination Network Porous Crystal Composite Membrane
[0059] (1) As shown in the gas separation device Figure 5 , the gas separation device is a Wicke-Kallenbach device. The dipeptide metal coordination network porous crystal composite membrane is sandwiched between two pieces of aluminum foil tape, and the edges are further sealed with a sealant. For the mixed gas separation performance test, the flow rate of the equimolar mixed raw materials is adjusted by a mass flow controller. The total volume flow rate is maintained at 100 mL / min (50 mL / min for each gas). Ar with a flow rate of 25 mL / min is used as the sweep gas on the permeate side, and the permeate gas is delivered to an on-line gas chromatograph (Panna).
[0060] (2) Gas Separation of Dipeptide Metal Coordination Network Composite Membranes with Different Thicknesses under Single-Component Gases
[0061] The dipeptide metal coordination network porous crystal composite membranes prepared in Example 1 and Example 2 are used to replace the composite membrane in the above gas separation device respectively, and other conditions remain unchanged. The effects of dipeptide metal coordination network membranes with different thicknesses on gas separation permeability and selectivity under different single-component gases (separate carbon dioxide or separate nitrogen instead of the mixed gas in step (1)) are tested. The results are as shown in Figure 6 . It can be seen from Figure 6 that the permeability and ideal selectivity of the dipeptide metal coordination network porous crystal composite membrane with a growth time of 18 h are the most suitable.
[0062] (3) Gas Separation Performance of Dipeptide Metal Coordination Network Composite Membrane with Optimal Thickness under Single-Component Gases
[0063] The membrane with the best performance, that is, the dipeptide metal coordination network porous crystal composite membrane with a growth time of 18 h in Example 1, is used to replace the composite membrane in the above gas separation device, and other conditions remain unchanged. The effects of dipeptide metal coordination network membranes on gas separation permeability and selectivity under different single-component gases are tested, and compared with the Knudsen diffusion selectivity (Knudsen), a simple screening criterion based on physical size. The results are as shown in Figure 7 . It can be seen from Figure 7 that the membrane prepared in this work has great advantages in separating CO2 / N2, far exceeding the Knudsen diffusion selectivity.
[0064] Example 4 Gas Separation of Dipeptide Metal Coordination Network Composite Membrane under Different CO2 Partial Pressures
[0065] The dipeptide metal coordination network porous crystal composite membrane with a growth time of 18 h in Example 1 is used to replace the composite membrane in the above gas separation device, and other conditions remain unchanged. The effects of dipeptide metal coordination network membranes on gas separation permeability and selectivity under different CO2 partial pressures are tested. The results are as followsFigure 8 as shown
[0066] Figure 8 For the gas separation permeability and selectivity of the dipeptide metal coordination network membrane under different CO2 partial pressures in Example 4, from Figure 8 it can be found that when the CO2 pressure reaches 0.2 MPa, the CO2 permeability and the CO2 / N2 selectivity factor (SF) show a steep upward trend and tend to balance. The maximum CO2 permeability reaches 1553 GPU, and the selectivity factor reaches 41, which far exceeds the separation requirements for economical and energy-saving carbon capture in industry (CO2 permeability > 1000 GPU and CO2 / N2 selectivity > 20).
[0067] Comparative Example 1
[0068] Previously publicly reported:
[0069] ZnTCPP membrane: M. Liu, K. Xie, M. D. Nothling, P. A. Gurr, S. S. L. Tan, Q. Fu, P. A. Webley, G. G. Qiao, ACS Nano 2018, 12, 11591 - 11599.
[0070] Pebax 2533 membrane: Z. Qin, X. Feng, D. Yin, B. Xin, Z. Jin, Y. Deng, L. Yang, L. Yao, W. Jiang, C. Liu, Z. Dai, Industrial & Engineering Chemistry Research 2023, 62, 14034 - 14046.
[0071] Pebax-ZIF-8 membrane: J. Deng, Z. Dai, L. Deng, Industrial & Engineering Chemistry Research 2020, 59, 14458 - 14466.
[0072] UiO-66-NO2 / ZIF-94 membrane: L. Martínez-Izquierdo, C. García-Comas, S. Dai, M. Navarro, A. Tissot, C. Serre, C. Téllez, J. Coronas, ACS Applied Materials & Interfaces 2024, 16, 4024 - 4034.
[0073] Polyactive / P@MOF: K. Xie, Q. Fu, J. Kim, H. Lu, Y. He, Q. Zhao, J. Scofield, P. A. Webley, G. G. Qiao, Journal of Membrane Science 2017, 535, 350 - 356.
[0074] Compare the CO2 permeability and CO2 / N2 selectivity factor of the above existing membranes with those of the dipeptide metal coordination network porous crystal composite membrane (This work) in Example 1. The results are as follows Figure 9 shown. The performance of this work significantly exceeds the 2008 Robeson (2008 upper bound) upper limit, and the CO2 permeability or CO2 / N2 selectivity factor of other membranes is lower than the performance of this work.
[0075] Stability test of gas separation of the dipeptide metal coordination network porous crystal composite membrane in Example 5
[0076] The experimental procedure was the same as in Example 4, carried out at a CO2 pressure of 0.2 MPa, and the results are as follows Figure 10 shown. Figure 10 Gas separation test within 60 h of the dipeptide metal coordination network porous crystal composite membrane prepared in Example 1. From Figure 10 the experimental results, it was found that the dipeptide metal coordination network porous crystal composite membrane showed good stability in the application of gas separation. After 60 h of testing, the permeability and separation selectivity factor hardly decayed, laying a solid foundation for practical applications.
Claims
1. A porous crystal composite film of a dipeptide metal coordination network, characterized in that, The dipeptide metal coordination network porous crystal composite membrane includes a self-assembled dipeptide metal coordination network membrane and an amino-functionalized membrane material with a macroporous structure. Some pores in the self-assembled dipeptide metal coordination network membrane correspond to and communicate with some macropores in the amino-functionalized membrane material with a macroporous structure.
2. The dipeptide metal coordination network porous crystal composite membrane according to claim 1, wherein The membrane material with a macroporous structure is anodic aluminum oxide membrane, and the pore diameter of the anodic aluminum oxide membrane is 50 - 100 nm.
3. The dipeptide metal coordination network porous crystal composite film according to claim 1, characterized in that The dipeptide metal coordination network membrane is in-situ grown on the AAO substrate by coordinating a dipeptide linker with metal ions Zn, and the thickness of the dipeptide metal coordination network membrane is about 200 - 220 nm.
4. The preparation method of the dipeptide metal coordination network porous crystal composite membrane according to any one of claims 1-3, characterized in that, It includes the following steps: (1) Dissolve the dipeptide linker in a methanol solvent and perform ultrasonic treatment to obtain a uniform mixed solution; (2) Place the amino-functionalized membrane material with a macroporous structure and the mixed solution together in a reaction vessel, add a catalyst, and fix at room temperature to form the first layer of dipeptide linker membrane; (3) Dissolve the metal compound Zn(NO3)2·6H2O in a solvent, add it to the reaction vessel, and carry out a heating reaction to in-situ grow the dipeptide metal coordination network porous crystal composite membrane.
5. The preparation method according to claim 4, characterized in that, In step (1), the dipeptide linker is glycyl-glycine, glycyl-alanine, or glycyl-serine. The concentration of the dipeptide linker in the solution after dissolving in the methanol solvent is 5 - 20 mmol / L, and the ultrasonic treatment time is 10 - 20 min.
6. The preparation method according to claim 4, wherein In step (2), the catalyst is a NaOH solution. The mixed solution in the reactor submerges the amino-functionalized membrane material with a macroporous structure, and the fixing time at room temperature is 6 - 12 h.
7. The preparation method according to claim 4, characterized in that In step (3), different thicknesses of the dipeptide metal coordination network membrane can be obtained by changing the in-situ growth time. The heating reaction temperature is 80 - 100 °C, and the heating reaction time is 12 - 24 h.
8. Application of the dipeptide metal coordination network porous crystal composite membrane according to any one of claims 1 - 3 in gas separation.
9. The application according to claim 8, wherein The gas contains CO2 and N2, and the CO2 / N2 volume ratio is (1:9) - (9:1).
10. The application according to claim 9, characterized in that, The partial pressure of CO2 gradually increases, and the performance is the best when the partial pressure of CO2 is above 0.2 MPa.