Azif nanofiller, preparation method, homogeneous interface-mediated mixed matrix membrane and preparation method and application thereof

Abstract

The application belongs to the technical field of gas separation membranes, and particularly relates to AZIF nano-filler, a preparation method, a homogeneous interface-mediated mixed matrix membrane and a preparation method and application thereof. The preparation method of the homogeneous interface-mediated mixed matrix membrane is to prepare a metal organic framework / self-microporous polymer mixed matrix membrane by blending a long molecular chain AOPIM-1 polymer as a membrane matrix with AZIF nano-filler. The homogeneous interface-mediated mixed matrix membrane prepared by the application significantly improves the interface compatibility between the filler and the membrane matrix, while the inherent pore channel screening characteristics of the organic framework material are maintained, rich selective nano-diffusion channels are provided, and efficient separation of propylene / propane is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas separation membranes, and particularly relates to an AZIF nano filler, a preparation method, a homogeneous interface-mediated mixed matrix membrane and a preparation method and application thereof. BACKGROUND

[0002] As a key raw material in the petrochemical industry, the demand for propylene is continuously driven by the demand for downstream industrial products, and is expected to maintain an annual growth rate of 3.4% by 2030. Since the downstream polymer-grade product requires propylene with a purity higher than 99.5%, it is crucial to separate and purify propylene from light hydrocarbon mixtures, especially from propane. At present, the separation of propylene and propane mainly relies on low-temperature rectification technology, but this technology has the disadvantages of high energy consumption and low separation efficiency.

[0003] Membrane separation technology is a non-thermal driven separation method, which can significantly reduce energy consumption compared with low-temperature distillation technology, making it a promising alternative with low energy consumption and high propylene / propane separation efficiency. The development of high permeability and high selectivity membrane materials is crucial for propylene / propane separation. Metal-organic framework materials (MOFs) have shown good separation efficiency in adsorption-dominated penetration experiments due to their regular pore structure, high specific surface area and designable pore characteristics, which also reflects their good application prospect in membrane separation. Mixed matrix membranes are expected to combine the excellent separation characteristics of MOF materials and the processability of polymer matrices, and become a research hotspot for the development of high-efficiency propylene / propane separation membranes. However, due to the differences in the physical and chemical properties of the filler and the polymer membrane matrix, the polymer-filler phase interface is not compatible, and the MOF filler is usually unevenly dispersed in the membrane, causing the existence of non-selective defects. Therefore, the development of high-performance MOF mixed matrix membranes is challenging. At present, functionalization of MOF materials has also been proposed to effectively improve the compatibility of MOF and polymer matrix, but the commonly used functionalization method usually involves a cumbersome post-processing process and relies on the matching between MOF and polymer, which limits its wide application. Therefore, the simple design of new high-permeability and selectivity membrane materials is the key to realizing propylene / propane membrane separation. SUMMARY

[0004] The purpose of the present application is to provide an AZIF nano filler, a preparation method, and a homogeneous interface-mediated mixed matrix membrane and a preparation method and application thereof, to provide a simple strategy for solving the compatibility problem of mixed matrix membrane filler and polymer matrix, and to realize high-efficiency propylene / propane separation.

[0005] To solve the above technical problems, the technical solutions adopted by the present application are as follows:

[0006] An AZIF nanofiller is obtained by the following preparation method: using a amine oxime-modified self-porous polymer AOPIM-1 oligomer as a regulator, the synthesis and preparation of zeolite imidazole framework ZIF-8 is carried out by in-situ coordination regulation; the weight average molecular weight of the AOPIM-1 oligomer is 5.2 kDa.

[0007] Furthermore, a mixed solution of AOPIM-1 oligomer and 2-methylimidazole was thoroughly mixed with a solution of Zn(NO3)2·6H2O and reacted, followed by post-treatment to obtain AZIF nanoparticles; the mass ratio of AOPIM-1 oligomer to Zn(NO3)2·6H2O in the reaction solution was 1:100-500.

[0008] Furthermore, the reaction is carried out at 30-50°C for 1-2 hours.

[0009] The mass ratio of AOPIM-1 oligomer to 2-methylimidazole in the mixed solution of AOPIM-1 oligomer and 2-methylimidazole is 1:110 to 550.

[0010] The Zn(NO3)2·6H2O solution is a solution of Zn(NO3)2·6H2O and 2-methylimidazole dissolved in dimethyl sulfoxide. The molar concentration of Zn(NO3)2·6H2O in the solution is 0.25-0.35 mol / L, preferably 0.3 mol / L; the molar concentration of dimethylimidazole is 1.0-1.4 mol / L, preferably 1.2 mol / L.

[0011] The preferred molar ratio of Zn(NO3)2·6H2O to 2-methylimidazole is 1:4.

[0012] The post-processing involves centrifuging and washing the reaction product, followed by vacuum drying at 60-80℃ for 8-12 hours to obtain AZIF nanoparticles.

[0013] Specifically, Zn(NO3)2·6H2O and 2-methylimidazole were dissolved in dimethyl sulfoxide and magnetically stirred at room temperature for 5-10 min; AOPIM-1 oligomer was dissolved in 2-methylimidazole solution and stirred at room temperature for 1 h; the mixed solution of AOPIM-1 oligomer and 2-methylimidazole was added dropwise to Zn(NO3)2·6H2O solution and the mixture was reacted in a water bath at 30-50℃ for 1-2 h; AZIF powder was collected by centrifugation, washed, and vacuum dried at 60-80℃ for 8-12 h to obtain AZIF nanoparticles.

[0014] The present invention further provides a method for preparing a homogeneous interface-mediated hybrid matrix membrane, which uses a long molecular chain AOPIM-1 polymer as the membrane matrix and blends it with the AZIF nanofiller to prepare a metal-organic framework / self-porous polymer hybrid matrix membrane.

[0015] Furthermore, AZIF nanoparticles were fully dispersed in an organic solvent to obtain a dispersion with a mass concentration of 0.12-0.85 wt%, and then AOPIM-1 polymer was dissolved in the dispersion; the mass concentration of AZIF nanoparticles in the mixed matrix film was 5-20 wt%.

[0016] The organic solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0017] Furthermore, AZIF nanoparticles were dispersed in an organic solvent and subjected to alternating stirring and ultrasonic treatment for 12-24 hours; AOPIM-1 polymer was dissolved in the AZIF dispersion and stirred for another 24 hours.

[0018] The resulting mixture solution can then be poured into a petri dish and dried in an oven at 80°C for 24-48 hours. After the solvent has evaporated, it can be vacuum dried at 80°C for 12-24 hours to obtain the mixed matrix membrane.

[0019] The AOPIM-1 polymer and AOPIM-1 oligomers described in this invention can be prepared using existing technologies.

[0020] More specifically, a method for preparing a homogeneous interface-mediated metal-organic framework / self-porous polymer hybrid matrix membrane includes the following steps:

[0021] 1) Preparation of AZIF nanoparticles: Zn(NO3)2·6H2O and 2-methylimidazole were dissolved in dimethyl sulfoxide and magnetically stirred at room temperature for 5-10 min; AOPIM-1 oligomer was dissolved in 2-methylimidazole solution and stirred at room temperature for 1 h; the mixed solution of AOPIM-1 oligomer and 2-methylimidazole was added dropwise to Zn(NO3)2·6H2O solution and the mixture was reacted in a water bath at 30-50℃ for 1-2 h; AZIF powder was collected by centrifugation, washed, and vacuum dried at 60-80℃ for 8-12 h to obtain AZIF nanoparticles;

[0022] 2) Preparation of the mixed matrix membrane: The AZIF nanoparticles obtained in step 1) were dispersed in an organic solvent and stirred and sonicated alternately for 12-24 h; AOPIM-1 polymer was dissolved in the AZIF dispersion and stirred for another 24 h; the mixture was vacuum dried to remove the solvent and obtain the mixed matrix membrane.

[0023] The hybrid matrix membrane has excellent applications in propylene / propane gas separation.

[0024] This invention employs a amine oxime-modified microporous polymer (AOPIM-1) oligomer to perform in-situ coordination regulation of the synthesis of zeolite imidazole salt framework ZIF-8, thereby obtaining AZIF nanoparticles with controllable size and functionalization.

[0025] Using the AZIF nanoparticles prepared in this invention as fillers and the long-chain AOPIM-1 polymer as the membrane matrix, a mixed matrix membrane with good interfacial compatibility, high permeability and selectivity can be constructed by blending.

[0026] Choosing the AZIF of this invention as a packing material for the preparation of propylene / propane separation membranes has several advantages:

[0027] First, the flexible pore structure of ZIF-8 allows its effective pore size to be between... Suitable for sieving propylene / propane; secondly, the amylopectin groups on the side chains of AOPIM-1 oligomers are suitable for Zn. 2+ The coordination effect of AOPIM-1 can effectively reduce the surface energy of the crystal and inhibit the Ostwald ripening process during crystal growth, resulting in a uniform particle size distribution of nanoparticles. Third, the macromolecular structure of AOPIM-1 oligomers prevents them from entering the pores of the metal-organic framework, ensuring specific regulation of the surface properties of the filler and effectively maintaining the inherent porosity of ZIF-8. Fourth, the AOPIM-1 oligomers on the AZIF surface and the AOPIM-1 polymer in the membrane matrix have the same structural characteristics, which helps to build a homogeneous interface between the filler phase and the polymer phase. Good interfacial compatibility can optimize the dispersion of the filler in the membrane, form continuous nanopores that facilitate the transport of propylene molecules, and retain the sieving characteristics for propane molecules, achieving effective separation of propylene / propane. Fifth, the molecular entanglement of AOPIM-1 oligomers and the polymer matrix at the phase interface can effectively limit the migration of polymer segments and improve the anti-aging and anti-plasticization properties of the membrane.

[0028] This invention utilizes AOPIM-1 oligomers as coordination modifiers in the synthesis of ZIF-8, enabling the one-step synthesis of functionalized organic framework materials (MOFs) and the simplified design of highly permeable and selective membrane materials. On one hand, it precisely controls the ZIF-8 crystal growth process and surface properties without affecting its inherent porosity; on the other hand, the AOPIM-1 oligomers on the surface of the nanofiller construct a homogeneous interface between the filler and the membrane matrix.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The homogeneous interface-mediated hybrid matrix membrane prepared by this invention significantly improves the interfacial compatibility between the filler and the membrane matrix, while maintaining the inherent pore sieving characteristics of organic framework materials. It constructs a homogeneous interface between metal-organic framework filler and self-contained microporous polymer matrix, optimizes the dispersion characteristics of the filler in the membrane and forms an interconnected network structure, provides abundant selective nanodiffusion channels, and achieves efficient separation of propylene / propane. Attached Figure Description

[0031] Figure 1 These are SEM images of the cross-sections of the hybrid matrix membranes obtained in Examples 1, 2, and 3 of this invention.

[0032] Figure 2 The graph shows the long-term separation performance of the mixed matrix membrane obtained in Example 2 of this invention for propylene / propane mixed gas under different temperatures and pressures. Detailed Implementation

[0033] The technical solution of the present invention is illustrated below with specific embodiments, but the scope of protection of the present invention is not limited thereto: Embodiment 1

[0034] A method for preparing an AZIF nanoparticle and homogeneous interface-mediated metal-organic framework / self-porous polymer hybrid matrix membrane, comprising the following steps:

[0035] 1) Weigh 1.786 g of Zn(NO3)2·6H2O and 1.97 g of 2-methylimidazole and dissolve them in 20.0 mL of dimethyl sulfoxide (99.7% v / v, the same below), and stir at room temperature for 10 min. Weigh 0.004 g of AOPIM-1 oligomer and dissolve it in the 2-methylimidazole solution, and stir at room temperature for 1 h. Add the resulting mixed solution dropwise to the Zn(NO3)2·6H2O solution. Then, transfer the above mixture to a water bath and stir at 40 °C for 1 h. After the reaction is complete, collect the product by centrifugation, wash thoroughly with anhydrous methanol, and vacuum dry overnight at 75 °C to obtain AZIF nanoparticles.

[0036] 2) Disperse 0.028 g of the above nanoparticles in 8 mL of N,N-dimethylformamide (99.5% by volume, the same below), and alternately stir and sonicate the dispersion for 12 h. Then, weigh 0.25 g of AOPIM-1 polymer and dissolve it in the above dispersion, and stir at room temperature for 24 h. Pour the resulting mixture into a smooth horizontal petri dish with a diameter of 6 cm and place it in an oven at 80 °C for 48 h to evaporate the solvent. After the solvent has evaporated, vacuum dry at 80 °C for 12 h to completely remove the residual solvent. The resulting mixed matrix membrane is labeled AOPIM / AZIF-1.

[0037] Example 2

[0038] A method for preparing an AZIF nanoparticle and homogeneous interface-mediated metal-organic framework / self-porous polymer hybrid matrix membrane, comprising the following steps:

[0039] 1) Weigh 1.786 g of Zn(NO3)2·6H2O and 1.97 g of 2-methylimidazole and dissolve them separately in 20.0 mL of dimethyl sulfoxide. Stir at room temperature for 10 min. Weigh 0.009 g of AOPIM-1 oligomer and dissolve it in the 2-methylimidazole solution. Stir at room temperature for 1 h. Add the resulting mixed solution dropwise to the Zn(NO3)2·6H2O solution. Then, transfer the above mixture to a water bath and stir at 40 °C for 1 h. After the reaction is complete, collect the product by centrifugation, wash thoroughly with anhydrous methanol, and vacuum dry overnight at 75 °C to obtain AZIF nanoparticles.

[0040] 2) 0.044 g of the above nanoparticles were dispersed in 8 mL of N,N-dimethylformamide, and the dispersion was alternately stirred and sonicated for 12 h. Then, 0.25 g of AOPIM-1 polymer was weighed and dissolved in the above dispersion, and stirred at room temperature for 24 h. The resulting mixture was poured into a smooth horizontal petri dish with a diameter of 6 cm and placed in an oven at 80 °C for 48 h to evaporate the solvent. After the solvent evaporated, it was vacuum dried at 80 °C for 12 h to completely remove the residual solvent. The resulting mixed matrix membrane was labeled AOPIM / AZIF-2.

[0041] Example 3

[0042] A method for preparing an AZIF nanoparticle and homogeneous interface-mediated metal-organic framework / self-porous polymer hybrid matrix membrane, comprising the following steps:

[0043] 1) Weigh 1.786 g of Zn(NO3)2·6H2O and 1.97 g of 2-methylimidazole and dissolve them separately in 20.0 mL of dimethyl sulfoxide. Stir at room temperature for 10 min. Weigh 0.018 g of AOPIM-1 oligomer and dissolve it in the 2-methylimidazole solution. Stir at room temperature for 1 h. Add the resulting mixed solution dropwise to the Zn(NO3)2·6H2O solution. Then, transfer the above mixture to a water bath and stir at 40 °C for 1 h. After the reaction is complete, collect the product by centrifugation, wash thoroughly with anhydrous methanol, and vacuum dry overnight at 75 °C to obtain AZIF nanoparticles.

[0044] 2) 0.044 g of the above nanoparticles were dispersed in 8 mL of N,N-dimethylformamide, and the dispersion was alternately stirred and sonicated for 12 h. Then, 0.25 g of AOPIM-1 polymer was weighed and dissolved in the above dispersion, and stirred at room temperature for 24 h. The resulting mixture was poured into a smooth horizontal petri dish with a diameter of 6 cm and placed in an oven at 80 °C for 48 h to evaporate the solvent. After the solvent evaporated, it was vacuum dried at 80 °C for 12 h to completely remove the residual solvent. The resulting mixed matrix membrane was labeled AOPIM / AZIF-3.

[0045] Comparative Example 1

[0046] The preparation steps of the unmodified ZIF-8 hybrid matrix membrane are as follows:

[0047] 1) Weigh 1.786 g of Zn(NO3)2·6H2O and 1.97 g of 2-methylimidazole and dissolve them separately in 20.0 mL of dimethyl sulfoxide. Stir at room temperature for 10 min, then add the 2-methylimidazole solution dropwise to the Zn(NO3)2·6H2O solution. Transfer the mixture to a water bath and stir at 40 °C for 1 h. After the reaction is complete, collect the product by centrifugation, wash thoroughly with anhydrous methanol, and vacuum dry overnight at 75 °C to obtain ZIF-8 nanoparticles.

[0048] 2) 0.028 g of the above nanoparticles were dispersed in 8 mL of N,N-dimethylformamide, and the dispersion was alternately stirred and sonicated for 12 h. Then, 0.25 g of AOPIM-1 polymer was weighed and dissolved in the above dispersion, and stirred at room temperature for 24 h. The resulting mixture was poured into a smooth horizontal petri dish with a diameter of 6 cm and placed in an oven at 80 °C for 48 h to evaporate the solvent. After the solvent evaporated, it was vacuum dried at 80 °C for 12 h to completely remove the residual solvent. The resulting mixed matrix membrane was labeled AOPIM / ZIF-8.

[0049] Comparative Example 2

[0050] The preparation steps of AOPIM-1 pure-phase polymer membrane are as follows:

[0051] 0.25 g of AOPIM-1 polymer was weighed and dissolved in N,N-dimethylformamide, and stirred at room temperature for 24 h. The resulting polymer solution was poured into a smooth horizontal petri dish with a diameter of 6 cm and placed in an oven at 80 °C for 48 h to evaporate the solvent. After the solvent evaporated, the mixture was vacuum dried at 80 °C for 12 h to completely remove any residual solvent. The resulting mixed matrix membrane was labeled AOPIM.

[0052] Table 1 shows the propylene / propane gas permeation coefficient and selectivity of the AOPIM / AZIF hybrid matrix membranes prepared in Examples 1-3, the AOPIM / ZIF-8 and AOPIM membranes prepared in Comparative Examples 1-2, and the gas separation membranes reported in the literature.

[0053] Table 1

[0054]

[0055] As can be seen from Table 1, compared with the mixed matrix membranes reported in the literature (ZIF-67 / 6FDA-DAM, prepared according to NatMater.19(12)(2020)1346-1353; Zr-fum-fcu-MOF / 6FDA-DAM, prepared according to AdvMater.31(14)(2019)1807513; UiO-66 / 6FDA-DAM, prepared according to Angew Chem IntEd.60(23)(2021)13081-13088; 6FDA-DAM / KAUST-7, prepared according to AdvMater.35(25)(2023)2300296; ZIF-8-CN / PIM-1, prepared according to AdvMater.34(6)(2022)2104606), the mixed matrix membrane prepared in this invention maintains a high propylene / propane separation capacity while also exhibiting a high permeability advantage. The mixed matrix membrane prepared by AZIF obtained by coordination regulation of AOPIM-1 oligomers has improved permeability and selectivity. The propylene permeability coefficient of Example 2 increased to 267.6 Barrer, which is about 1.9 times that of Comparative Example 1, while the selectivity increased to 27.3, which is about 1.5 times that of Comparative Example 1.

Claims

1. A method for preparing AZIF nanofillers, characterized in that, The zeolite imidazole framework ZIF-8 was synthesized by in-situ coordination regulation using a methylamine oxime-modified microporous polymer AOPIM-1 oligomer as a regulator; the weight-average molecular weight of the AOPIM-1 oligomer was 5.2 kDa; the mixed solution of AOPIM-1 oligomer and 2-methylimidazole was thoroughly mixed with a solution of Zn(NO3)2·6H2O and reacted, and then post-treated to obtain AZIF nanoparticles; the mass ratio of AOPIM-1 oligomer to Zn(NO3)2·6H2O in the reaction solution was 1:100~500.

2. The method for preparing AZIF nanofillers as described in claim 1, characterized in that, The mass ratio of AOPIM-1 oligomer to 2-methylimidazole in the mixed solution of AOPIM-1 oligomer and 2-methylimidazole is 1:110~550.

3. The AZIF nanofiller obtained by any of the preparation methods of claim 1 or 2.

4. A method for preparing a homogeneous interface-mediated hybrid matrix membrane, characterized in that, A metal-organic framework / self-porous polymer hybrid matrix membrane was prepared by blending the long molecular chain AOPIM-1 polymer with the AZIF nanofiller described in claim 3.

5. The method for preparing a homogeneous interface-mediated hybrid matrix membrane as described in claim 4, characterized in that, AZIF nanoparticles were fully dispersed in an organic solvent to obtain a dispersion with a mass concentration of 0.12-0.85 wt%, and then AOPIM-1 polymer was dissolved in the dispersion; the mass concentration of AZIF nanoparticles in the mixed matrix film was 5-20 wt%.

6. The method for preparing a homogeneous interface-mediated hybrid matrix membrane as described in claim 5, characterized in that, The organic solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

7. The method for preparing a homogeneous interface-mediated hybrid matrix membrane as described in claim 5, characterized in that, AZIF nanoparticles were dispersed in an organic solvent and subjected to alternating stirring and sonication for 12-24 h; AOPIM-1 polymer was dissolved in the AZIF dispersion and stirred for another 24 h; the mixture was then vacuum dried to remove the solvent and obtain a mixed matrix film.

8. A homogeneous interface-mediated hybrid matrix membrane obtained by any of the preparation methods of claims 4-7.

9. The application of the hybrid matrix membrane of claim 8 in propylene / propane gas separation.

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