Cu-ba-ad and a preparation method thereof, and a mixed matrix membrane of the cu-ba-ad and application thereof

Abstract

The application belongs to the technical field of metal-organic framework materials and gas membrane separation, and specifically discloses a Cu-BA-AD and a preparation method thereof, a Cu-BA-AD mixed matrix membrane and application thereof. The application adopts a microwave-assisted synthesis method, and through synergistically regulating a microwave reaction time, a reaction temperature and a precursor concentration, a synthesis cycle is greatly shortened to 1 minute, and continuous gradient regulation of Cu-BA-AD particle sizes in the range of 1.2 mu m to 100 nm is realized. The obtained Cu-BA-AD nanoparticles have regular morphologies and smaller sizes, and a specific surface area is between 550 m 2 / g. When the Cu-BA-AD nanoparticles are used as fillers to prepare a mixed matrix membrane, the interface compatibility can be significantly improved, and the separation flux and selectivity of CO2 / CH4 can be greatly improved.

Description

Technical Field

[0001] This invention relates to the field of metal-organic framework material preparation technology, and particularly to a Cu-BA-AD and its preparation method, a Cu-BA-AD mixed matrix film and its application. Background Technology

[0002] Metal-organic frameworks (MOFs) are periodic network porous materials formed by the self-assembly of inorganic metal ions and organic ligands through coordination bonds. Due to their high porosity, regular and highly tunable pore size structure, and high specific surface area, they show broad application prospects in gas adsorption and separation, catalysis, and electrochemistry. In practical applications of gas membrane separation, the particle size of MOFs affects their dispersibility and interfacial compatibility; therefore, precise control of crystal size is crucial to fully realizing their application efficiency.

[0003] Cu-BA-AD, as an emerging porous material, has attracted much attention for its inherent microporous characteristics in specific functional applications. However, existing Cu-BA-AD synthesis methods mostly rely on traditional liquid-phase processes such as room-temperature stirring, which generally suffer from drawbacks such as long synthesis cycles and large product particles. According to the classical nucleation and growth model, under the traditional heating mechanism, precursor monomers slowly diffuse and combine to the surface of stable crystal nuclei, leading to easy further crystal growth and making it difficult to achieve fine and continuous particle size gradient control.

[0004] In recent years, microwave-assisted synthesis technology has attracted widespread attention as a highly efficient heating method. Microwaves achieve extremely rapid overall heating through electromagnetic radiation and the interaction of molecular dipole polarization. Its unique high-frequency electromagnetic field energy forces the system's supersaturation to rise sharply, thereby triggering extremely violent "explosive nucleation." This mechanism enables a large number of crystal nuclei to be generated simultaneously and rapidly deplete the reactants, successfully separating the nucleation stage from the growth stage, thus effectively inhibiting further crystal growth and significantly shortening the synthesis cycle.

[0005] Although microwave synthesis offers significant advantages in preparing small-sized MOFs, systematic research is still lacking on how to achieve precise control of Cu-BA-AD particle size over a wide range using a microwave reactor through multi-dimensional synergistic regulation of reaction time, temperature, and concentration. Therefore, there is an urgent need to provide a Cu-BA-AD preparation method based on precise particle size control using a microwave reactor to overcome the bottleneck in its practical application. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides Cu-BA-AD and its preparation method, Cu-BA-AD mixed matrix membrane and its application.

[0007] The first objective of this invention is to provide a method for preparing Cu-BA-AD, comprising the following steps: firstly, copper nitrate trihydrate (Cu(NO3)2·3H2O) and adenine (HAD) ligand are dissolved in N,N-dimethylformamide (DMF), and succinic acid (H2BA) ligand and potassium carbonate (K2CO3) are dissolved in water. Then, the obtained DMF solution is added to the aqueous solution and mixed evenly. The mixture is placed in a microwave reactor for reaction. After the reaction is completed, the product is collected by centrifugation, washed, activated and dried to finally obtain Cu-BA-AD powder.

[0008] By adopting the above technical solution, DMF was used instead of the commonly used DMA solvent in existing technologies, and microwave heating technology was combined. Under the action of the microwave high-frequency electromagnetic field, the precursor can overcome the energy barrier in a very short time, shortening the synthesis time from the conventional tens of hours to 1 minute, resulting in a significant reduction in the size of the final Cu-BA-AD particles to the nanoscale. In addition, the low-boiling-point DMF is more easily and completely activated and removed at lower temperatures, making it easier to clean the pores and release more gas adsorption sites during subsequent activation.

[0009] Preferably, the molar ratio of Cu(NO3)2·3H2O to HAD ligand is 1:1, the molar ratio of H2BA ligand to K2CO3 is 2:1, and the volume ratio of DMF to water is 2:1.

[0010] By adopting the above technical solution, the optimal feeding ratio of metal ions and ligands and the mixed solvent environment are provided. While ensuring the high purity and phase structure integrity of Cu-BA-AD crystals, a stable precursor concentration basis is provided for the subsequent large-scale generation of crystal nuclei.

[0011] Preferably, the particle size of Cu-BA-AD can be gradient-controlled within the range of 1.2μm-100nm by synergistically regulating the microwave reaction time, microwave reaction temperature, and precursor concentration of the reaction system.

[0012] Preferably, the microwave reaction time is 1-5 minutes; the shorter the reaction time, the smaller the size of the obtained Cu-BA-AD particles. When the reaction time is shortened from 5 minutes to 1 minute, the particle size is reduced from about 850 nm to about 500 nm.

[0013] By employing the above technical solution, the law that crystal growth in microwave synthesis depends on residence time was demonstrated. The longer the reaction time, the more time the crystal nuclei in the system have to grow, resulting in an increase in crystal size. Precisely shortening the reaction time to 1 minute can effectively cut off the later stages of crystal growth and initially control the particle size at the submicron level.

[0014] Preferably, the microwave reaction temperature is 85-120°C. oC; The higher the reaction temperature, the smaller the size of the resulting Cu-BA-AD particles. When the reaction temperature increases from 85°C... o C rose to 105 o At temperature C, the particle size decreased from 900 nm to 500 nm, and the temperature was further increased to 115 °C. o C-120 o At C, the particle size remains at 500 nm, and a size decay plateau occurs.

[0015] By employing the above technical solution, the positive correlation between nucleation rate and temperature is utilized. Localized microwave overheating at high temperatures leads to the instantaneous generation of a large number of crystal nuclei, consuming a significant amount of raw materials. Consequently, the amount of monomers allocated to each crystal nucleus for growth decreases, effectively reducing crystal size. The plateau period that appears in the later stages of heating indicates that when the nucleation driving force of the system reaches the temperature-dominated critical threshold, the size will reach its minimum under those conditions.

[0016] Preferably, the concentration of Cu(NO3)2·3H2O or HAD ligand in the reaction system is 30-120 mmol / L. The higher the concentration of the reaction system, the smaller the size of the resulting Cu-BA-AD particles. When the concentration of the reaction system increases from 30 mmol / L to 120 mmol / L, the particle size decreases from 1.2 μm to 200 nm. When the concentration of the reaction system is further increased, the particle size remains at 200 nm, and a size decay plateau occurs.

[0017] By employing the above-mentioned technical solution, when temperature control is limited, increasing the concentration of the reaction solution leads to a sharp increase in the supersaturation of the system. This extremely high supersaturation forces the system to undergo more intense "explosive nucleation," successfully separating the nucleation stage from the growth stage. This allows a large number of crystal nuclei to be generated simultaneously and to deplete the reactants, thereby breaking through the temperature bottleneck and further compressing the particle size to 200 nm.

[0018] Preferably, when the concentration of Cu(NO3)2·3H2O in the reaction system reaches 120 mmol / L and the particle size shrinks to 200 nm, encountering a bottleneck, the microwave reaction temperature is reduced from 105 mmol / L. o C increased to 125 o C further reduces the size of the resulting Cu-BA-AD nanoparticles to approximately 100 nm.

[0019] Preferably, when further increasing the concentration encounters a bottleneck due to size reduction, the microwave temperature is increased to 125°C. o C further endows the system with higher reaction energy, thereby breaking the original limit of nucleation driving force and reducing the particle size limit to 100nm.

[0020] Preferably, the washing, activation, and drying steps involve washing the obtained powder three times sequentially with DMF, water, and methanol, followed by placing it at 60°C. o The Cu-BA-AD was activated and dried in a vacuum oven for 12 hours. The BET specific surface area of ​​the prepared Cu-BA-AD ranged from 550 to 695 m². 2 Between / g.

[0021] By adopting the above technical solution, using gradient washing with solvent and vacuum drying at a lower temperature, the unreacted precursors and DMF solvent remaining in the pores can be completely removed without causing the framework to collapse. This ensures the excellent pore structure and high specific surface area of ​​the prepared material, providing sufficient active sites for gas adsorption and membrane separation.

[0022] The second objective of this invention is to provide a Cu-BA-AD metal-organic framework material obtained by the above-mentioned preparation method, using the following technical solution: A metal-organic framework material, Cu-BA-AD, is prepared using the aforementioned method for preparing Cu-BA-AD metal-organic framework materials. Its particle size ranges from 1.2 μm to 100 nm, and its specific surface area is between 550 and 695 m². 2 Between / g.

[0023] By adopting the above technical solution, small-sized metal-organic framework material Cu-BA-AD particles with large specific surface area are obtained. The Cu-BA-AD mixed matrix membrane prepared by incorporating them as filler into 6FDA-DAM polymer effectively improves the interfacial bonding state and has excellent separation performance for CO2 / CH4.

[0024] Beneficial technical effects of the present invention: (1) Highly efficient synthesis with controllable size gradient: Compared with traditional heating methods, which have long preparation cycles, large particle sizes, and are difficult to precisely control, this invention adopts a microwave-assisted synthesis strategy, which significantly shortens the synthesis cycle to 1 minute. Through multi-dimensional synergistic control of reaction time, reaction temperature, and reaction solution concentration, a gradient size design of Cu-BA-AD from 1.2 μm to 100 nm was successfully achieved, solving the problem that existing technologies cannot achieve fine gradient control of Cu-BA-AD particle size.

[0025] (2) Green optimization of synthesis conditions: This invention uses low-boiling-point DMF as a solvent, combined with the characteristics of microwave rapid heating, to achieve full activation and pore cleaning of the material at a lower temperature. Compared with traditional synthesis methods, this process is more efficient and more conducive to releasing more gas adsorption sites during subsequent activation, thereby significantly improving the specific surface area of ​​the material and providing ideal conditions for the preparation of high-performance separation packings.

[0026] (3) Superior performance of the hybrid matrix membrane: The Cu-BA-AD nanoparticles prepared in this invention have advantages such as regular morphology and large specific surface area. Using them as fillers in a polymer matrix to prepare a hybrid matrix membrane can effectively improve the interfacial bonding state between the filler and the polymer matrix, eliminating non-ideal interfacial defects. Experimental results show that under optimal control conditions, the obtained hybrid matrix membrane exhibits extremely high CO2 permeability and good selectivity in CO2 / CH4 separation, significantly outperforming the original polymer membrane and surpassing existing technologies. It has broad industrial application prospects in fields such as natural gas decarbonization and purification. Attached Figure Description

[0027] Figure 1 (a) PXRD patterns of samples from Examples 1-3, (b) PXRD patterns of samples from Examples 3-7, (c) PXRD patterns of samples from Examples 3, 8-13, and (d) PXRD patterns of samples from Comparative Example 1, Examples 3, 10, and 12-14.

[0028] Figure 2 (a) Nitrogen adsorption isotherms of samples 1-3 at 77K, (b) Nitrogen adsorption isotherms of samples 3-7 at 77K, (c) Nitrogen adsorption isotherms of samples 3, 8-13 at 77K, and (d) Nitrogen adsorption isotherms of samples 3, 10, 12-14 at 77K.

[0029] Figure 3 (a) is a SEM image of the sample from Example 1, (b) is a SEM image of the sample from Example 2, and (c) is a SEM image of the sample from Example 3.

[0030] Figure 4 (a) is the SEM image of sample 4, (b) is the SEM image of sample 5, (c) is the SEM image of sample 6, and (d) is the SEM image of sample 7.

[0031] Figure 5 (a) SEM image of sample 1 (Comparative Example 1), (b) SEM image of sample 3 (Example 3), (c) SEM image of sample 10 (Example 10), (d) SEM image of sample 12 (Example 12), (e) SEM image of sample 13 (Example 13), and (f) SEM image of sample 14 (Example 14).

[0032] Figure 6(a) CO2 / CH4 separation performance of Cu-BA-AD mixed matrix membranes with different filler loadings for Example 3 sample at 500 nm; (b) CO2 / CH4 separation performance of Cu-BA-AD mixed matrix membranes for Example 3 sample at 500 nm, Example 10 sample at 400 nm, Example 12 sample at 300 nm, Example 13 sample at 200 nm, and Example 14 sample at 100 nm; (c) CO2 / CH4 separation performance of Cu-BA-AD mixed matrix membranes with different filler loadings for Example 14 sample at 200 nm.

[0033] Figure 7 (a) Comparison of the separation performance of Cu-BA-AD-200nm / 6FDA-DAM MMMs with the 2008 separation performance limit line, the 2019 separation performance limit line and existing technology materials. Detailed Implementation

[0034] Example 1

[0035] A method for preparing a metal-organic framework material Cu-BA-AD includes the following steps: First, Cu(NO3)2·3H2O (0.64 g) and HAD ligand (0.36 g) are dissolved in 30 ml of DMF; H2BA ligand (0.16 g) and K2CO3 (0.094 g) are dissolved in 15 ml of water. Then, the DMF solution is added to the aqueous solution, and the reaction is carried out at 105 °C for 5 minutes in a microwave reactor (Makewave, MKM-H1B). The reaction product is collected by centrifugation, and the resulting powder is washed three times sequentially with DMF, water, and methanol. o After activation in a vacuum oven at C for 12 hours, Cu-BA-AD powder with a size of approximately 850 nm was finally obtained.

[0036] Example 2 The microwave reaction time in Example 2 was 3 minutes, and all other conditions were the same as those in Example 1.

[0037] Example 3 The microwave reaction time in Example 3 was 1 minute, and all other conditions were the same as those in Example 1.

[0038] The time taken for the preparation process in Examples 1-3 above and the dimensions of the final metal-organic framework material Cu-BA-AD products are shown in Table 1.

[0039] Table 1. Dimensions of Cu-BA-AD materials at different reaction times

[0040] Examples 4-7 A method for preparing a metal-organic framework material Cu-BA-AD includes the following steps: except that the microwave reaction time is kept at 1 minute and the microwave reaction temperature is set at 85℃, 95℃, 115℃ and 120℃ respectively, the rest are the same as the steps in Example 1, and metal-organic framework material Cu-BA-AD particles are obtained respectively.

[0041] The microwave reaction temperature used in the preparation process of Examples 4-7 above and the dimensions of the final obtained metal-organic framework material Cu-BA-AD products are shown in Table 2.

[0042] Table 2. Dimensions of Cu-BA-AD materials at different reaction temperatures

[0043] Examples 8-13 A method for preparing a metal-organic framework material Cu-BA-AD specifically includes the following steps: except for maintaining the microwave reaction temperature at 105 °C. o C. The microwave reaction time is 1 minute. The total volume of the solvent is kept constant. The feed mass of copper nitrate and ligand is changed. The molar ratio of metal salt and ligand is kept constant so that the concentration of Cu(NO3)2·3H2O in the reaction system is 30 mmol / L, 45 mmol / L, 75 mmol / L, 90 mmol / L, 105 mmol / L and 120 mmol / L respectively. All other steps are the same as in Example 1. Metal-organic framework material Cu-BA-AD particles are obtained respectively.

[0044] The microwave reaction temperature used in the preparation process of Examples 8-13 above and the dimensions of the final metal-organic framework material Cu-BA-AD products are shown in Table 3.

[0045] Table 3. Dimensions of Cu-BA-AD materials with different reaction concentrations

[0046] Example 14

[0047] A method for preparing a metal-organic framework material Cu-BA-AD specifically includes the following steps: raising the microwave reaction temperature to 125°C while maintaining a reaction system concentration of 120 mmol / L. o C. The microwave reaction time is maintained for 1 minute, and the rest of the steps are the same as in Example 1, to obtain Cu-BA-AD metal-organic framework material particles.

[0048] The final size of the metal-organic framework material Cu-BA-AD product obtained in the preparation process of Example 14 above is 100 nm.

[0049] Comparative Example 1: Synthesis of Cu-BA-AD(RT) filler (no microwave synthesis, solvent: DMA) First, Cu(NO3)2·3H2O (6.4 g) and HAD ligand (3.2 g) were dissolved in 300 ml of DMA, and H2BA ligand (1.6 g) and K2CO3 (1 g) were dissolved in 150 ml of water. Then, the DMA solution was added to the aqueous solution, and the mixture was stirred vigorously at room temperature for 48 hours. The reaction product was collected by centrifugation, and the resulting powder was washed several times with DMA, water, and methanol. The final product was then subjected to a 60°C test. o After activation in a vacuum oven at C for 12 hours, Cu-BA-AD powder was finally obtained.

[0050] The Cu-BA-AD packings prepared in Examples 1-14 and Comparative Example 1 were characterized as follows: (1) Powder X-ray diffraction (PXRD) analysis The crystal structures of Cu-BA-AD samples synthesized under different microwave reaction times, temperatures, and reaction solution concentrations were characterized using powder X-ray diffraction (PXRD). Figure 1 As shown in (a)-(d), the PXRD patterns of Cu-BA-AD powders with different particle sizes prepared in this invention all exhibit high consistency and are in high agreement with theoretical simulation results. This confirms that the microwave-assisted synthesis method used in this invention does not cause a phase transformation or framework collapse in the material. This preparation method achieves a wide range of particle size control from 1.2 μm to 100 nm while maintaining excellent crystallinity and phase purity, ensuring the structural stability required for its use as a separation filler.

[0051] (2) Analysis of nitrogen adsorption isotherm at 77K The prepared gradient-size Cu-BA-AD particles were analyzed by nitrogen adsorption isotherm analysis at 77 K. Figure 2 As shown in (a)-(d), all samples exhibit typical Type I nitrogen adsorption isotherm characteristics, confirming that the nanoparticles maintained a well-preserved microporous framework structure during the intense microwave nucleation process. With the controlled conditions driving the particle size to continuously decrease, the BET specific surface area of ​​the material showed a significant upward trend. This phenomenon indicates that the small-sized nanoscale Cu-BA-AD exposes more specific surface area, and its internal channels are more thoroughly cleaned under vacuum activation, releasing more effective gas diffusion channels. Through microwave-assisted synthesis, precise control of the material particle size was achieved while effectively maintaining the original pore characteristics and crystal integrity of the MOF. The corresponding Brunauer-Emmett-Teller (BET) specific surface area and micropore volume data of the Cu-BA-AD material are listed in Table 4.

[0052] Table 4. Pore structure characteristics of different Cu-BA-AD materials.

[0053]

[0054] (3) Scanning electron microscopy (SEM) analysis Scanning electron microscope (SEM) images such as Figure 3-5 The results showed that all Cu-BA-AD particles obtained by microwave-assisted synthesis exhibited highly regular, well-defined octahedral morphologies without crystal distortion. When controlling the microwave reaction time, such as... Figure 3 (a)-(c), as the reaction time was shortened from 5 min to 1 min, the crystal growth process was effectively interrupted, and the particle size was significantly reduced from approximately 850 nm to approximately 500 nm. When controlling the microwave reaction temperature, such as... Figure 4 (a)-(d), under the premise of a reaction time of 1 min, as the reaction temperature increases from 85... o C rose to 105 o At C, higher energy input accelerated the nucleation rate, reducing the particle size from approximately 900 nm to approximately 500 nm; further heating to 120°C... o At temperature C, the size remained around 500 nm, indicating that the system had reached the limiting plateau in the competition between metal ion diffusion and complexation rates. After controlling the microwave reaction concentration to break through the temperature plateau, as... Figure 5 (a)-(f), as the drug concentration in the reaction system gradually increases, the supersaturation of the system rises sharply, and the particle size shows a significant decreasing trend, reducing the particle size from 1.2 μm to approximately 200 nm. When the reaction temperature is further increased to 125 °C... o At temperature C, Cu-BA-AD nanoparticles with a size of approximately 100 nm were prepared. SEM images confirmed that the microwave-assisted synthesis method proposed in this invention achieved good preservation of the Cu-BA-AD particle morphology, and through the synergistic control of time, temperature, and concentration, the particle size was precisely designed within the range of 1.2 μm to 100 nm, providing an ideal filler structure support for subsequent optimization of the interfacial compatibility of the hybrid matrix film.

[0055] Compared to other transition metals, the copper ions in this invention possess a d9 electronic configuration and are influenced by the Jameer-Taylor effect, resulting in an uneven distribution of coordination bond strength during coordination crystallization of the Cu-BA-AD system. This microstructural feature accelerates the coordination bonding rate of the crystal in specific directions. Under traditional liquid-phase heating mechanisms, this system easily forms a kinetic mode of low nucleation rate and rapid local growth; therefore, Cu-BA-AD crystals in existing technologies are easily grown to the micrometer scale. This invention introduces a microwave-assisted synthesis strategy, providing the energy required to overcome the nucleation energy barrier in an extremely short time, bringing the system to an extremely supersaturated state, thereby triggering a simultaneous explosive nucleation of a massive number of crystal nuclei. This mechanism instantly consumes a large amount of precursors, curbing the uncontrolled coordination of precursors in specific directions and achieving separation of the nucleation and growth stages. This invention further combines the multidimensional synergy of microwave reaction time, temperature, and precursor concentration, successfully breaking through the inherent thermodynamic and kinetic size decay plateau of this system, achieving gradient control of the material particle size in the range of 1.2 μm to 100 nm.

[0056] Application Examples

[0057] The metal-organic framework material Cu-BA-AD products obtained in Examples 3, 10, 12, 13, and 14 above were used as fillers in the preparation of mixed matrix membranes for CO2 / CH4 separation. The preparation process specifically includes the following steps: First, Cu-BA-AD powder was dispersed in 3 mL of chloroform and sonicated for 30 minutes to obtain a homogeneous suspension. Then, 137.04 mg of 6FDA-DAM polymer was dissolved in the Cu-BA-AD suspension and physically blended, with continuous stirring for 24 hours to obtain the casting solution. The resulting casting solution was dropwise into a polytetrafluoroethylene (PTFE) petri dish using a solution casting method and allowed to slowly evaporate in a saturated chloroform atmosphere at room temperature for 24 hours. After film formation, the film sample was placed at 60°C. o The mixed matrix membrane is obtained by drying in a vacuum oven for 12 hours, wherein the loading of Cu-BA-AD powder is 10wt%-40wt%.

[0058] Cu-BA-AD loading (wt%) = m Cu-BA-AD / (m Cu-BA-AD +m 聚合物 )×100%(1) The Cu-BA-AD / 6FDA-DAM mixed matrix membrane obtained above was characterized as follows: CO2 / CH4 separation performance of membrane materials To verify the separation capability of the Cu-BA-AD hybrid matrix membrane, at 25°C... oC. Gas separation tests were conducted under a feed pressure of 1 bar, with equal volumes of CO2 and CH4 injected into the mixed gas. The gas separation performance of a 500 nm Cu-BA-AD mixed matrix membrane with different loadings was systematically tested. Figure 6 (a) indicates that the incorporation of Cu-BA-AD simultaneously improved both the CO2 permeability and CO2 / CH4 selectivity of the membrane sample. When the filler loading increased from 10 wt% to 30 wt%, the CO2 permeability of the membrane sample significantly increased from 784.68 Barrer to 1137.83 Barrer, and the CO2 / CH4 selectivity increased from 23.6 to 31.49. The gradual increase in CO2 permeability with increasing filler loading indicates that the introduction of nano-sized Cu-BA-AD provides an additional transport path for gas permeation. However, when the filler loading was further increased to 35 wt%, the CO2 permeability significantly increased to 1661.55 Barrer, while the CO2 / CH4 selectivity decreased to 26.3. This phenomenon is attributed to the formation of non-selective voids at the filler-polymer interface within the membrane.

[0059] To further investigate the effect of packing size on the separation performance of mixed matrix membranes, this invention tested the separation performance of 100-500 nm Cu-BA-AD mixed matrix membranes at a loading of 30 wt%. Test Results Figure 6 (b) shows that as the Cu-BA-AD particle size decreased from 500 nm to 200 nm, the CO2 permeability of the membrane significantly increased from 1137.83 Barrer to 1449.58 Barrer, while the CO2 / CH4 selectivity increased from 31.49 to 40.02. This is attributed to the larger specific surface area of ​​the 200 nm filler and its better interfacial compatibility with the polymer; the smaller nanoparticles can effectively eliminate interfacial defects and construct an ideal compatible interface. However, when the particle size decreased to 100 nm (CO2 permeability 1573.46 Barrer, CO2 / CH4 selectivity 30.61), the extremely high surface energy of the nanoparticles led to severe agglomeration during film formation, weakening the molecular sieving ability.

[0060] Based on establishing the optimal particle size of 200nm Cu-BA-AD, this invention further breaks through to higher loading levels. For example... Figure 6(c) This indicates that the 35wt% Cu-BA-AD-200nm / 6FDA-DAM mixed matrix membrane exhibits optimal separation performance, with a CO2 permeability of 1593.84 Barrer and an optimal CO2 / CH4 selectivity of 43.13, significantly better than the original 6FDA-DAM polymer membrane (CO2 permeability 593.44 Barrer, CO2 / CH4 selectivity 18.49) and other Cu-BA-AD mixed matrix membranes. Compared to the non-selective voids that appear in large-particle-size packings under the same loading, the 200nm packing successfully withstood a high loading of 35wt%. Furthermore, compared with other CO2 / CH4 separation research reports in recent years (Table 5), this invention demonstrates better CO2 / CH4 separation performance, and the separation performance of the 35wt% Cu-BA-AD-200nm / 6FDA-DAM mixed matrix membrane exceeds the separation performance limit line of 2008. Figure 7 ).

[0061] Table 5. Comparison of CO2 / CH4 separation performance of hybrid matrix membranes reported in recent years and the membranes obtained in this invention.

Claims

1. A method for preparing Cu-BA-AD, characterized in that, The process includes the following steps: First, Cu(NO3)2·3H2O and adenine HAD ligand are dissolved in N,N-dimethylformamide DMF, and succinic acid ligand H2BA and potassium carbonate are dissolved in water. Then, the obtained DMF solution is added to the aqueous solution and mixed evenly. The mixture is placed in a microwave reactor for reaction. After the reaction is completed, the product is collected by centrifugation, washed, activated and dried to finally obtain Cu-BA-AD powder.

2. The method for preparing Cu-BA-AD according to claim 1, characterized in that: The molar ratio of Cu(NO3)2·3H2O to HAD ligand is 1:1, the molar ratio of H2BA ligand to K2CO3 is 2:1, and the volume ratio of DMF to water is 2:

1.

3. The preparation method of Cu-BA-AD according to claim 1, characterized in that: The Cu-BA-AD particle size ranges from 1.2 μm to 100 nm.

4. The preparation method of Cu-BA-AD according to claim 3, characterized in that: The microwave reaction time is 1-5 minutes.

5. The method for preparing Cu-BA-AD according to claim 3, characterized in that: The microwave reaction temperature is 85-120°C. o C.

6. The method for preparing Cu-BA-AD according to claim 3, characterized in that: The concentration of Cu(NO3)2·3H2O or HAD ligand in the reaction system is 30-120 mmol / L.

7. The method for preparing Cu-BA-AD according to claim 1, characterized in that: The washing, activation, and drying steps involve washing the obtained powder three times sequentially with DMF, water, and methanol, followed by placing it at 60°C. o Activate and dry in a vacuum oven for 12 hours.

8. A Cu-BA-AD prepared by any one of claims 1-7, characterized in that: The Cu-BA-AD particles range in size from 1.2 μm to 100 nm, with a specific surface area between 550 and 695 m². 2 Between / g.

9. A Cu-BA-AD hybrid matrix membrane, characterized in that: The Cu-BA-AD obtained by the preparation method according to any one of claims 1-7 is incorporated into the 6FDA-DAM polymer as a filler, wherein the filler loading is 10-35 wt%.

10. The application of the Cu-BA-AD hybrid matrix membrane as described in claim 9 in CO2 / CH4 separation.

Images