Preparation method for promoting transfer of metal organic framework membrane by using amino acid as CO2 active carrier

Abstract

The invention provides a preparation method of a promoted transfer metal organic framework membrane using amino acid as a CO2 active carrier. The preparation method comprises the following steps: sequentially adding a metal source, an organic ligand and amino acid into a mixed solution containing a solvent and a regulator, dissolving to obtain a reaction precursor solution, and then preparing an amino acid-containing promoted transfer MOF membrane on a porous carrier by using an in-situ growth method or a seed crystal method; in the reaction process, amino acid serving as a competitive coordination reagent is coordinated with metal ions / clusters of an MOF skeleton, so that the amino acid is tightly combined with the skeleton, and the coordination regulation effect also inhibits the too fast crystallization reaction of MOF in a bulk phase to ensure the controllable nucleation and growth of a film layer. The prepared MOF film is compact and continuous; the modified MOF membrane shows excellent CO2 separation performance in a wide humidity range (relative humidity of 0-100%) environment due to the CO2 promotion transfer effect of the amino acid active carrier under high humidity and the screening effect of inherent sub-nanometer mass transfer pore channels of the MOF membrane on CO2 under low humidity.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane separation, and in particular relates to a method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers. Background Art

[0002] Flue gas emitted from the combustion of fossil fuels in the power and heating industries (primarily composed of CO2, N2, and water vapor, with the specific composition depending on the fuel type, combustion technology, unit capacity, and purification equipment) is the largest source of CO2 emissions globally. The capture, utilization, and storage (CCUS) of CO2 from flue gas can significantly reduce anthropogenic CO2 emissions without unduly impacting current economic infrastructure and the existing energy structure. Traditional CCUS technologies suffer from low efficiency, high energy consumption, and high operating costs, which limit their practical application in industry. As a new separation process, membrane technology is increasingly being used in the field of flue gas CO2 separation due to its advantages such as energy efficiency, environmental friendliness, simple operation, and high integration.

[0003] Membrane materials, at the core of membrane separation technology, are crucial for achieving efficient separation processes. Currently, commercial polymer membranes struggle to overcome the trade-off between selectivity and permeability. In contrast, facilitated transport membranes (FTMs), created by introducing specific active carrier amino groups into polymer membranes, exploit the reversible chemical reaction between the amino groups and CO₂ and H₂O, allowing CO₂ to be chemically adsorbed as carbamate or bicarbonate ions and diffuse across the membrane at ultrafast speeds, achieving simultaneous improvements in both CO₂ permeability and selectivity. However, the separation performance of ammonia-containing FTMs is highly dependent on humidity. At low relative humidity (less than 70%), CO₂ separation performance significantly decreases due to the poor kinetics and unfavorable reaction equilibrium of the CO₂ hydration reaction. In recent years, molecular sieve membranes have shown promising application prospects in flue gas separation due to their advantages, including suitable pore size, adjustable skeleton structure, and high thermal and chemical stability. However, at high humidity, the microporous mass transfer channels of zeolite membranes become clogged by a large number of H₂O molecules that compete with CO₂ for adsorption, significantly reducing CO₂ separation performance.

[0004] Amino acids, rich in amino groups, possess strong CO₂ absorption capacity, fast hydration reaction kinetics, and high stability. Compared to other types of facilitated transport membranes, facilitated transport polymer membranes incorporating them as active carriers exhibit higher CO₂ mass transfer efficiency and separation performance at high humidity. Furthermore, metal-organic frameworks (MOFs), self-assembled from metal ions (or metal-oxoclusters) coordinated with organic ligands, are ideal CO₂ separation membrane materials due to their strong CO₂ affinity and uniform pore structure. If amino acids can be used as coordination modulators, leveraging their carboxylic acid groups to coordinate with the metal ions (or metal-oxoclusters) of the MOF, thereby firmly embedding the amino acids into the framework, amino acid-containing facilitated transport MOF membranes can be prepared. It is expected that by combining the CO₂-facilitating effect of amino acids as active carriers at high humidity with the CO₂-sieving effect of the MOF membrane's inherent subnanometer mass transfer pores at low humidity, MOF membranes will exhibit excellent CO₂ separation performance over a wide humidity range (0-100% relative humidity), meeting the practical needs of flue gas separation. However, there is still a lack of research in this area. Summary of the Invention

[0005] To address specific challenges faced in practical industrial separation applications, the present invention provides a method for preparing a metal-organic framework (MOF) membrane that utilizes amino acids as active carriers for CO2 transport. A metal source, an organic ligand, and an amino acid are sequentially added to a mixed solution containing a solvent and a modifier, and dissolved to obtain a reaction precursor solution. Subsequently, a dense, amino acid-containing MOF membrane for transport transport is prepared on a porous support using an in situ growth method or a seed crystallization method. This preparation process is simple, low-cost, highly reproducible, easily scalable, and widely applicable. The prepared membrane exhibits good connectivity and stability, demonstrating excellent CO2 separation performance across a wide humidity range (relative humidity 0-100%). This provides a practical solution to the challenges of stable operation and large-scale production of MOF membranes for industrial flue gas CO2 separation applications.

[0006] Preferably, the molar ratio of the amino acid to the organic ligand is 1:0.1-10, and the molar ratio of the amino acid to the metal source is 1:0.1-10.

[0007] The method for preparing a metal-organic framework membrane that utilizes amino acids as CO2 active carriers specifically comprises the following steps:

[0008] (1) After uniformly mixing the solvent and the regulator, a metal source, an organic ligand, and an amino acid are sequentially added and dissolved to obtain a reaction precursor solution;

[0009] (2) An unmodified porous carrier or a porous carrier coated with MOF seeds is fixed and placed in a reactor, and the above-mentioned reaction precursor solution is added to the reactor, followed by a solvent thermal reaction; during the reaction, the amino acid acts as a competitive coordination agent to coordinate with the metal ions (or metal oxygen cluster nodes) of the MOF skeleton, not only making the amino acid tightly bound to the skeleton, but also this coordination regulation effect inhibits the excessively rapid crystallization process of MOF in the bulk phase, thereby precisely controlling the nucleation and growth of the MOF film layer on the carrier surface;

[0010] (3) After the reaction is completed, a continuous and dense amino acid-promoting MOF membrane is obtained through washing and drying.

[0011] Preferably, the amino acid is at least one of histidine, arginine, lysine, glycine, alanine, sarcosine, proline, cysteine, valine, leucine, isoleucine, methionine, tryptophan, serine, tyrosine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, selenocysteine, pyrrolysine, citrulline, ornithine and hydroxyproline.

[0012] Preferably, the solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, dimethyl sulfoxide, cyclohexane, acetone, water, methanol, ethanol, and propanol; the regulator is at least one of formic acid, acetic acid, hydrochloric acid, nitric acid, benzoic acid, difluoroacetic acid, and trifluoroacetic acid; and the metal source is a zirconium-based metal source, a titanium-based metal source, or a zinc-based metal source.

[0013] Preferably, the zirconium source comprises one of zirconium n-propoxide, Zr6-oxo cluster, zirconium tetrachloride, zirconium oxychloride, zirconium disulfide, zirconium trisulfide, organic zirconium and zirconium acetate.

[0014] Preferably, the titanium source includes one of isopropyl titanate, titanium dioxide, titanium trioxide, titanium sulfate, titanium tetrachloride, titanium propoxide, titanium disulfide, titanium trisulfide and titanium bromide.

[0015] The zinc source comprises one of zinc formate, zinc acetate, zinc acetylacetonate, zinc nitrate, zinc chloride and zinc bromide.

[0016] Preferably, the molar ratio of the metal source to the regulator is 1:10-5000, and the molar ratio of the metal source to the solvent is 1:10-5000.

[0017] The MOF membrane and the corresponding organic ligands are preferably of the following types: terephthalic acid corresponding to MIL-140A, UiO-66 and MIL-125; 2,6-naphthalene dicarboxylic acid corresponding to MIL-140B; 2-aminoterephthalic acid corresponding to UiO-66-NH2; nitroterephthalic acid corresponding to UiO-66-NO2; 2,5-dihydroxyterephthalic acid corresponding to UiO-66-(OH)2; UiO-66-CH 3 corresponds to 2-methylterephthalic acid; UiO-66-Br corresponds to 2-bromotetrabenzoquinone; MIL-140C and UiO-67 correspond to 4,4'-biphenyldicarboxylic acid; UiO-68 corresponds to terphenyldicarboxylic acid; UiO-66-1,4-Naph corresponds to 1,4-naphthalene dicarboxylic acid; MOF-801 corresponds to fumaric acid; MOF-802 corresponds to 1H-pyrazole-3,5-dicarboxylic acid; MOF-805 corresponds to 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid; 3,3'-dihydroxy-4,4'-biphenyldicarboxylic acid corresponding to MOF-806; 1,3,5-benzenetricarboxylic acid corresponding to MOF-808; 4,4',4",4"'-tetramethyltetrabenzoic acid corresponding to MOF-812 or MOF-841; 1,3,6,8-tetrakis(p-benzoate)pyrene corresponding to NU-1000; PCN-221, PCN-222, PCN-2 23. Meso-tetrakis(4-carboxyphenyl)porphyrin corresponding to PCN-224 or PCN-225; 2,6-naphthalenedicarboxylic acid corresponding to DUT-52 or DUT-84; 2,5-thiophenedicarboxylic acid corresponding to DUT-67, DUT-68 or DUT-69; 9,10-anthryldibenzoic acid corresponding to Zr-ADC; 5,5'-methylenediisophthalic acid corresponding to MIP-177; 2-methylimidazole corresponding to ZIF-8.

[0018] Preferably, the dissolving in step (1) is ultrasonic dissolving or stirring dissolving.

[0019] Preferably, the MOF seed crystals described in step (2) are prepared by subjecting a precursor solution to a liquid phase reaction followed by washing and centrifugation. The dispersant for the MOF seed crystal solution is at least one of methanol, ethanol, propanol, butanol, and water; the seed crystal solution concentration is 0.01-10 wt.%; and the seed crystal coating method is preferably spin coating, dip coating, spray coating, wipe coating, or interfacial self-assembly.

[0020] Preferably, the solvent thermal reaction heating method in step (2) is convection heating or microwave heating; the convection heating is oven heating or oil bath heating, and the microwave heating is single-mode microwave heating or multi-mode microwave heating.

[0021] Preferably, the reaction time of step (2) is 1 min to 120 h.

[0022] Preferably, the type of the porous carrier is flat plate, tubular, coiled or hollow fiber; the type of the porous carrier is porous metal oxide, porous metal or porous non-metal oxide; the porous metal oxide is porous alumina, porous titanium oxide or porous yttrium oxide, the porous metal is porous stainless steel or porous nickel, and the porous non-metal oxide is porous silicon oxide, porous silicon carbide or porous glass.

[0023] Preferably, the drying temperature in step (3) is not higher than the decomposition temperature of the corresponding MOF membrane.

[0024] The MOF molecular sieve membrane has a grain size of 10 nm to 10 μm and a thickness of 10 nm to 10 μm.

[0025] The present invention also provides an application of the amino acid-containing metal organic framework membrane to separate CO2 from flue gas in an industrial wide humidity range environment.

[0026] The flue gas CO2 separation system is CO2 / N2, CO2 / H2 or CO2 / CH4; the relative humidity range of the separation environment is 0-100%.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] The present invention innovatively uses amino acids as competitive coordination regulators to prepare MOF membranes that promote transfer. On the one hand, during the reaction process, amino acids can coordinate with the metal ions (or metal oxygen cluster nodes) of the MOF skeleton and thus be firmly embedded in the skeleton. This can not only effectively adjust the size and shape of the MOF membrane mass transfer pores to achieve a more accurate CO2 screening effect, but also the amino sites in the amino acids with strong CO2 absorption capacity and excellent reaction kinetics can act as active carriers to undergo reversible nucleophilic addition reactions with CO2 and H2O in a high humidity environment, so that CO2 is chemically adsorbed in the form of carbamate ions or bicarbonate ions and diffuses across the membrane at an ultra-high speed, thereby achieving a significant improvement in CO2 separation performance in a high humidity environment; on the other hand, its competitive coordination regulation effect effectively inhibits the excessively fast crystallization reaction of MOF in the bulk phase, thereby precisely regulating the nucleation and growth rate of the MOF membrane layer on the carrier surface, and effectively eliminating the non-selective intergranular boundary defects of the membrane layer. The method provided by the present invention has strong universality, low cost, and good repeatability, and provides a new idea for the structural regulation of MOF membranes. The MOF membrane prepared by this method is continuous and dense, thanks to the CO2-promoting transfer effect of the amino acid active carrier under high humidity and the CO2 screening effect of the inherent sub-nanometer mass transfer channels of the MOF membrane under low humidity. It exhibits excellent CO2 separation performance in a wide humidity range (relative humidity 0-100%) and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a scanning electron microscope (SEM) image of the histidine-containing MIL-140A membrane prepared in Example 1;

[0030] Figure 2 This is the X-ray diffraction (XRD) pattern of the histidine-containing transfer-promoting MIL-140A membrane prepared in Example 1;

[0031] Figure 3 This is an infrared spectrum (FT-IR) of the histidine-enhanced transfer MIL-140A membrane prepared in Example 1;

[0032] Figure 4 This is a scanning electron microscope (SEM) image of the histidine-containing UiO-66 seed crystals prepared in Example 2;

[0033] Figure 5 This is the X-ray diffraction (XRD) pattern of the histidine-containing UiO-66 seed crystals prepared in Example 2;

[0034] Figure 6 This is an infrared spectrum (FT-IR) of the histidine-containing UiO-66 seed crystals prepared in Example 2;

[0035] Figure 7 This is a scanning electron microscope (SEM) image of the histidine-containing UiO-66 membrane prepared in Example 3;

[0036] Figure 8 This is the X-ray diffraction (XRD) pattern of the histidine-containing UiO-66 film prepared in Example 3;

[0037] Figure 9 This is a scanning electron microscope (SEM) image of the arginine-enhanced transport MOF-801 membrane prepared in Example 4;

[0038] Figure 10 This is the X-ray diffraction (XRD) pattern of the arginine-enhanced transport MOF-801 membrane prepared in Example 4;

[0039] Figure 11 This is a scanning electron microscope (SEM) image of the lysine-promoting transport MOF-808 membrane prepared in Example 5;

[0040] Figure 12 This is the X-ray diffraction (XRD) pattern of the lysine-containing transport-promoting MOF-808 membrane prepared in Example 5;

[0041] Figure 13 This is a scanning electron microscope (SEM) image of the UiO-67 membrane containing alanine-promoted transport prepared in Example 6;

[0042] Figure 14This is the X-ray diffraction (XRD) pattern of the UiO-67 film containing alanine-promoted transport prepared in Example 6;

[0043] Figure 15 This is a scanning electron microscope (SEM) image of the UiO-66-1,4-Naph membrane containing proline-promoting transport prepared in Example 7;

[0044] Figure 16 This is the X-ray diffraction (XRD) pattern of the UiO-66-1,4-Naph film containing proline-promoting transport prepared in Example 7;

[0045] Figure 17 This is a scanning electron microscope (SEM) image of the glycine-promoting UiO-66-Br membrane prepared in Example 8;

[0046] Figure 18 This is the X-ray diffraction (XRD) pattern of the UiO-66-Br film containing glycine-promoted transport prepared in Example 8;

[0047] Figure 19 This is a scanning electron microscope (SEM) image of the cysteine-containing UiO-66-(OH)2 membrane prepared in Example 9;

[0048] Figure 20 This is the X-ray diffraction (XRD) pattern of the cysteine-containing UiO-66-(OH)2 film prepared in Example 9;

[0049] Figure 21 This is a scanning electron microscope (SEM) image of the tryptophan-enhanced transfer MIL-125 membrane prepared in Example 10;

[0050] Figure 22 This is a scanning electron microscope (SEM) image of the phenylalanine-enhanced transport MIP-177 membrane prepared in Example 11;

[0051] Figure 23 This is the X-ray diffraction (XRD) pattern of the phenylalanine-enhanced transport MIP-177 membrane prepared in Example 11;

[0052] Figure 24 This is a scanning electron microscope (SEM) image of the phenylalanine-containing transport-promoting ZIF-8 membrane prepared in Example 12;

[0053] Figure 25 This is the X-ray diffraction (XRD) pattern of the phenylalanine-enhanced transport ZIF-8 membrane prepared in Example 12;

[0054] Figure 26 The CO2 / N2 separation performance of the histidine-promoted MIL-140A membrane in Example 13 at different relative humidities;

[0055] Figure 27 The CO2 / CH4 separation performance of the histidine-promoted MIL-140A membrane in Example 13 at different relative humidities;

[0056] Figure 28 The CO2 / N2 separation performance of the UiO-66 membrane containing histidine to promote transfer at different relative humidities in Example 14;

[0057] Figure 29 is the X-ray diffraction (XRD) pattern of the conventional MIL-140A film prepared in Comparative Example 1;

[0058] Figure 30 The scanning electron microscope (SEM) image of the conventional MIL-140A film prepared in Comparative Example 1;

[0059] Figure 31 This is a scanning electron microscope (SEM) image of the conventional UiO-66 film prepared in Comparative Example 2;

[0060] Figure 32 The X-ray diffraction (XRD) pattern of the conventional UiO-66 film prepared in Comparative Example 2 is shown. DETAILED DESCRIPTION

[0061] The present invention will be further described with reference to the following specific examples, but it should be noted that the present invention is not limited to the following examples.

[0062] Example 1

[0063] Preparation of membranes containing histidine to promote the delivery of MIL-140A

[0064] (1) 50 mL of N,N-dimethylformamide and 6 mL of acetic acid were uniformly mixed, and then 0.5 g of zirconium tetrachloride, 0.35 g of terephthalic acid, and 0.21 g of histidine were added in sequence. After ultrasonication for 20 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0065] (2) The unmodified porous alumina support was fixed and placed in a high-pressure reactor, and the above-mentioned reaction precursor solution was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 180°C for 96 hours;

[0066] (3) After the reaction is completed, a continuous and dense histidine-containing MIL-140A molecular sieve membrane can be obtained by washing and drying.

[0067] MIL-140A film plane and cross-section SEM Figure 1 As shown: the surface is dense and continuous, with no visible defects, and the film thickness is 4.5μm. XRD spectrum ( Figure 2 ) shows that all its characteristic diffraction peaks are completely matched with those of the standard MIL-140A phase, without any other impurity phases. The corresponding high-resolution infrared spectrum ( Figure 3 ) exhibited stretching vibrations corresponding to the histidine C-N, N-H, and C-H bonds, confirming the successful coordination of histidine to the zirconium-oxygen cluster nodes of the MIL-140A backbone.

[0068] Example 2

[0069] Preparation of UiO-66 Seed Crystals Containing Histidine

[0070] (1) 140 mL of N,N-dimethylformamide and 20 mL of acetic acid were uniformly mixed, and then 0.28 g of zirconium tetrachloride, 0.2 g of terephthalic acid, and 0.12 g of histidine were added in sequence. After ultrasonication for 10 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0071] (2) The above reaction precursor solution was added to a round-bottom flask, and then refluxed in an oil bath preheated to 120°C for 12 h;

[0072] (3) After the reaction is completed, the prepared histidine-containing UiO-66 seed crystals are washed with ethanol, centrifuged, and dried in a vacuum oven at 70°C overnight.

[0073] SEM of UiO-66 seed crystals Figure 4 As shown: Its morphology is regular and the size is uniform, with a size of 500nm. XRD spectrum ( Figure 5 ) shows that all its characteristic diffraction peaks are completely matched with those of the standard UiO-66 phase, without any other impurity phase. The high-resolution infrared spectrum of the UiO-66 seed crystal ( Figure 6 ) exhibited stretching vibrations corresponding to the histidine C-N, N-H, and C-H bonds, confirming the successful coordination of histidine to the zirconium-oxygen cluster nodes of the UiO-66 framework.

[0074] Example 3

[0075] Preparation of UiO-66 Membrane Containing Histidine to Promote Transport

[0076] (1) 140 mL of N,N-dimethylformamide and 20 mL of acetic acid were uniformly mixed, and then 0.28 g of zirconium tetrachloride, 0.2 g of terephthalic acid, and 0.12 g of histidine were added in sequence. After ultrasonication for 10 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0077] (2) The UiO-66 seed crystals in Example 2 were coated onto the surface of the porous alumina support and then dried in an oven at 90°C overnight;

[0078] (3) The porous alumina support coated with UiO-66 seeds was fixed and placed in a reactor, and the above-mentioned reaction precursor solution was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 120°C for 48 hours;

[0079] (4) After the reaction is completed, a continuous and dense UiO-66 molecular sieve membrane containing histidine-promoted transport can be obtained through washing and drying.

[0080] SEM of the plane and cross section of UiO-66 film Figure 7 As shown: the surface is dense and continuous, with no visible defects, and the film thickness is 5μm. XRD spectrum ( Figure 8 ) shows that all its characteristic diffraction peaks completely match those of the standard UiO-66 phase, without any other impurity phases.

[0081] Example 4

[0082] Preparation of MOF-801 membrane containing arginine-promoted transport

[0083] (1) 24 mL of deionized water and 6 mL of formic acid were uniformly mixed, and then 0.35 g of zirconium tetrachloride, 0.175 g of fumaric acid, and 0.13 g of arginine were added in sequence. After ultrasonication for 20 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0084] (2) The precursor solution was poured into a reactor and reacted in a convection oven preheated to 60°C for 18 hours. After the reaction, the prepared arginine-containing MOF-801 seed crystals were washed with ethanol, centrifuged, and dried in a vacuum oven at 60°C overnight. The seed crystals were then dip-coated on the surface of a large-area porous tubular alumina support and dried in an oven at 60°C overnight.

[0085] (3) The porous tubular alumina support coated with MOF-801 seed crystals was fixed and placed in a reactor, and the reaction precursor solution prepared according to step (1) was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 60° C. for 72 h;

[0086] (4) After the reaction is completed, a continuous and dense arginine-promoting MOF-801 molecular sieve membrane can be obtained by washing and drying.

[0087] MOF-801 membrane plane and cross-section SEM Figure 9 As shown: the film grows well, the surface is dense and continuous, there are no visible defects, and the film thickness is 1μm. XRD pattern ( Figure 10 ) shows that all its characteristic diffraction peaks completely match those of the standard MOF-801 phase, without any other impurity phases.

[0088] Example 5

[0089] Preparation of MOF-808 membrane containing lysine-promoted transport

[0090] (1) 15 mL of N,N-dimethylformamide and 15 mL of formic acid were uniformly mixed, and then 0.13 g of zirconium oxychloride octahydrate, 0.09 g of 1,3,5-benzenetricarboxylic acid, and 0.04 g of lysine were added in sequence. After ultrasonication for 30 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0091] (2) The unmodified porous alumina support was fixed and placed in a high-pressure reactor, and the above-mentioned reaction precursor solution was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 150°C for 48 hours;

[0092] (3) After the reaction is completed, a continuous and dense lysine-containing MOF-808 molecular sieve membrane that promotes transport can be obtained through washing and drying.

[0093] MOF-808 membrane plane and cross-section SEM Figure 11 As shown: the surface is dense and continuous, with no visible defects, and the film thickness is 6μm. XRD spectrum ( Figure 12 ) shows that all its characteristic diffraction peaks completely match those of the standard MOF-808 phase, without any other impurity phases.

[0094] Example 6

[0095] Preparation of UiO-67 Membrane Containing Alanine to Promote Transport

[0096] (1) 20 mL of N,N-dimethylformamide, 5 mL of formic acid, and 1 mL of deionized water were uniformly mixed, and then 0.35 g of zirconium n-propoxide, 0.175 g of 4,4'-biphenyldicarboxylic acid, and 0.06 g of alanine were added in sequence. The mixture was stirred for 10 min to uniformly dissolve the mixture to obtain a reaction precursor solution.

[0097] (2) The above reaction precursor solution was poured into a reactor and reacted in a convection oven preheated to 150°C for 24 hours; after the reaction, the prepared alanine-containing UiO-67 seed crystals were washed with ethanol, centrifuged, and dried in a vacuum oven at 80°C overnight; then coated on the surface of a porous alumina support and dried in an oven at 80°C overnight;

[0098] (3) The porous alumina support coated with UiO-67 seeds was fixed and placed in a reactor, and the reaction precursor solution prepared according to step (1) was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 150° C. for 48 h;

[0099] (4) After the reaction is completed, a continuous and dense UiO-67 molecular sieve membrane containing alanine-promoted transport can be obtained through washing and drying.

[0100] SEM of the plane and cross section of UiO-67 film Figure 13 As shown: the film grows well, the surface is dense and continuous, there are no visible defects, and the film thickness is 2μm. XRD spectrum ( Figure 14 ) shows that all its characteristic diffraction peaks completely match those of the standard UiO-67 phase, without any other impurity phases.

[0101] Example 7

[0102] Preparation of UiO-66-1,4-Naph Membranes Containing Proline to Promote Transport

[0103] (1) 140 mL of N,N-dimethylformamide and 20 mL of acetic acid were uniformly mixed, and then 0.39 g of zirconium n-propoxide, 0.26 g of 1,4-naphthalene dicarboxylic acid, and 0.08 g of proline were added in sequence. After ultrasonication for 30 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0104] (2) The above reaction precursor solution was poured into a reactor and reacted in a convection oven preheated to 120°C for 6 hours; after the reaction, the prepared proline-containing UiO-66-1,4-Naph seed crystals were washed with ethanol, centrifuged, and dried in a vacuum oven at 90°C overnight; then coated on the surface of a porous alumina support and dried in an oven at 90°C overnight;

[0105] (3) The porous alumina support coated with UiO-66-1,4-Naph seed crystals was fixed and placed in a reactor, and the reaction precursor solution prepared according to step (1) was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 120° C. for 24 h;

[0106] (4) After the reaction is completed, a continuous and dense UiO-66-1,4-Naph molecular sieve membrane containing proline-promoting transport can be obtained through washing and drying.

[0107] SEM images of the plane and cross section of UiO-66-1,4-Naph membrane Figure 15 As shown: the film grows well, the surface is dense and continuous, there are no visible defects, and the film thickness is 1μm. XRD pattern ( Figure 16 ) shows that all its characteristic diffraction peaks completely match those of the standard UiO-66-1,4-Naph phase, without any other impurity phases.

[0108] Example 8

[0109] Preparation of UiO-66-Br Membrane Containing Glycine-Facilitated Transport

[0110] (1) 140 mL of N,N-dimethylformamide and 20 mL of acetic acid were uniformly mixed, and then 0.39 g of zirconium n-propoxide, 0.3 g of 2-bromotetrabenzoquinone, and 0.09 g of glycine were added in sequence. After ultrasonication for 30 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0111] (2) The precursor solution was poured into a reactor and reacted in a convection oven preheated to 120°C for 12 hours. After the reaction, the prepared glycine-containing UiO-66-Br seed crystals were washed with ethanol, centrifuged, and dried in a vacuum oven at 90°C overnight. The seed crystals were then coated on the surface of a porous alumina support and dried in an oven at 90°C overnight.

[0112] (3) The porous alumina support coated with UiO-66-Br seed crystals was fixed and placed in a reactor, and the reaction precursor solution prepared according to step (1) was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 120° C. for 48 h;

[0113] (4) After the reaction is completed, a continuous and dense UiO-66-Br molecular sieve membrane containing glycine-promoted transport can be obtained through washing and drying.

[0114] SEM of the plane and cross section of UiO-66-Br film Figure 17 As shown: the film grows well, the surface is dense and continuous, there are no visible defects, and the film thickness is 1.5μm. XRD pattern ( Figure 18 ) shows that all its characteristic diffraction peaks completely match those of the standard UiO-66-Br phase, without any other impurity phases.

[0115] Example 9

[0116] Preparation of UiO-66-(OH)2 Membrane Containing Cysteine to Promote Transport

[0117] (1) 140 mL of N,N-dimethylformamide and 20 mL of acetic acid were uniformly mixed, and then 0.39 g of zirconium n-propoxide, 0.24 g of 2,5-dihydroxyterephthalic acid, and 0.15 g of cysteine were added in sequence. After ultrasonication for 20 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0118] (2) The above reaction precursor solution was poured into a reactor and reacted in a convection oven preheated to 150°C for 6 hours; after the reaction, the prepared cysteine-containing UiO-66-(OH)2 seed crystals were washed with ethanol, centrifuged, and dried in a vacuum oven at 90°C overnight; then coated on the surface of a porous alumina support and dried in an oven at 90°C overnight;

[0119] (3) The porous alumina support coated with UiO-66-(OH)2 seeds was fixed and placed in a reactor, and the reaction precursor solution prepared according to step (1) was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 150°C for 48 hours;

[0120] (4) After the reaction is completed, a continuous and dense cysteine-containing UiO-66-(OH)2 molecular sieve membrane can be obtained by washing and drying.

[0121] SEM of the plane and cross section of UiO-66-(OH)2 membrane Figure 19 As shown: the film grows well, the surface is dense and continuous, there are no visible defects, and the film thickness is 2.5μm. XRD pattern ( Figure 20 ) shows that all its characteristic diffraction peaks completely match the characteristic diffraction peaks of the standard UiO-66-(OH)2 phase, and there is no other impurity phase.

[0122] Example 10

[0123] Preparation of membranes containing tryptophan to promote the delivery of MIL-125

[0124] (1) 27 mL of N,N-dimethylformamide and 3 mL of methanol were uniformly mixed, and then 0.45 mL of isopropyl titanate, 0.39 g of terephthalic acid, and 0.46 g of tryptophan were added in sequence. After ultrasonication for 10 min, the mixture was completely dissolved to obtain a reaction precursor solution;

[0125] (2) The above reaction precursor solution was poured into a reactor and reacted in a convection oven preheated to 150°C for 12 hours; after the reaction, the prepared tryptophan-containing MIL-125 nanosheet seeds were washed with methanol, centrifuged, and dried in a vacuum oven at 90°C overnight; then coated on the surface of a porous alumina support and dried in an oven at 90°C overnight;

[0126] (3) 15 mL of N,N-dimethylformamide and 15 mL of methanol were uniformly mixed, and then 0.02 mL of isopropyl titanate, 0.26 g of terephthalic acid, and 0.31 g of tryptophan were added in sequence. After ultrasonication for 10 min, all of them were uniformly dissolved to obtain a growth precursor solution; a porous alumina support coated with MIL-125 nanosheets was fixed and placed in a quartz reactor, and the growth precursor solution was added to the reactor, and then a solvothermal reaction was carried out in a single-mode microwave oven at 150 ° C for 20 min;

[0127] (4) After the reaction is completed, a continuous and dense MIL-125 molecular sieve membrane containing tryptophan-promoting transport can be obtained through washing and drying.

[0128] MIL-125 film plane and cross-section SEM Figure 21 As shown: the film grows well, the surface is dense and continuous, there are no visible defects, and the film thickness is 1.5μm.

[0129] Example 11

[0130] Preparation of membranes containing phenylalanine-enhanced MIP-177

[0131] (1) 25 mL of N,N-dimethylformamide and 15 mL of formic acid were uniformly mixed, and then 0.13 mL of isopropyl titanate, 0.15 g of 5,5'-methylenediisophthalic acid, and 0.07 g of phenylalanine were added in sequence. After ultrasonication for 20 min, the mixture was uniformly dissolved to obtain a reaction precursor solution;

[0132] (2) The unmodified porous tubular alumina support was fixed and placed in a high-pressure reactor, and the above-mentioned reaction precursor solution was added to the reactor, followed by a solvothermal reaction in a convection oven preheated to 180°C for 72 hours;

[0133] (3) After the reaction is completed, a continuous and dense MIP-177 molecular sieve membrane containing phenylalanine-promoting transport can be obtained through washing and drying.

[0134] MIP-177 membrane plane and cross-section SEM Figure 22 As shown: the surface is dense and continuous, with no visible defects, and the film thickness is 4μm. XRD spectrum ( Figure 23 ) shows that all its characteristic diffraction peaks completely match those of the standard MIP-177 phase, without any other impurity phases.

[0135] Example 12

[0136] Preparation of ZIF-8 membrane containing phenylalanine to promote transport

[0137] (1) 17.5 mL of water and 7.5 mL of methanol were uniformly mixed, and then 0.05 g of zinc acetate dihydrate, 2.3 g of 2-methylimidazole, and 1.7 g of phenylalanine were added in sequence. After ultrasonication for 20 min, the mixture was completely dissolved to obtain a reaction precursor solution;

[0138] (2) The unmodified porous alumina support was fixed and placed in a high-pressure reactor, and the above-mentioned reaction precursor solution was added to the reactor, and then a solvothermal reaction was carried out in a convection oven preheated to 80°C for 24 hours;

[0139] (3) After the reaction is completed, a continuous and dense ZIF-8 molecular sieve membrane containing phenylalanine-promoting transport can be obtained through washing and drying.

[0140] SEM images of the ZIF-8 membrane plane and cross section Figure 24As shown: the surface is dense and continuous, with no visible defects, and the film thickness is 1.2μm. XRD spectrum ( Figure 25 ) shows that all its characteristic diffraction peaks completely match those of the standard ZIF-8 phase, without any other impurity phases.

[0141] Example 13

[0142] Separation performance of CO2 / N2 and CO2 / CH4 in flue gas using MIL-140A membrane with histidine-promoted transfer under a wide humidity range (relative humidity 0-100%)

[0143] The histidine-facilitated MIL-140A membrane prepared in Example 1 was tested for separation of CO₂ / N₂ and CO₂ / CH₄ mixed gases at various relative humidities. The test conditions were as follows: 30°C, a 1-bar pressure differential across the membrane, an equimolar feed of the mixed gases, and a pre-flow of the mixed gases through a steam generator before entering the membrane module to control the relative humidity of the feed gases. Helium was used as the purge gas.

[0144] The separation performance of MIL-140A membrane containing histidine to promote transport of CO2 / N2 and CO2 / CH4 at different relative humidity are shown in Figure 2. Figure 26 and Figure 27 The results show that it has excellent CO2 / N2 and CO2 / CH4 separation performance at different relative humidity: for CO2 / N2 separation at relative humidity of 0-100%, the separation factor is 44.8-57.3, and the CO2 permeability is 105.1-128.8×10 -9 mol·m -2 ·s -1 ·Pa -1 For CO2 / CH4 separation at relative humidity of 0-100%, the separation factor is 30.7-41.2, and the CO2 permeability is 94.3-129.2×10 -9 mol·m -2 ·s -1 ·Pa -1 .

[0145] Example 14

[0146] Performance test of flue gas CO2 / N2 separation using histidine-promoted UiO-66 membranes under a wide humidity range (relative humidity 0-100%)

[0147] The histidine-facilitated UiO-66 membrane prepared in Example 3 was tested for CO₂ / N₂ mixed gas separation at various relative humidities. The test conditions were as follows: 30°C, a 1-bar pressure differential across the membrane, an equimolar feed of the mixed gas, and a pre-flow of the mixed gas through a steam generator before entering the membrane module to control the relative humidity of the feed gas. Helium was used as the purge gas.

[0148] The CO2 / N2 separation performance of UiO-66 membrane containing histidine-promoted transport at different relative humidity is shown in Figure 2. Figure 28 The results show that it has excellent CO2 / N2 separation performance at different relative humidity (0-100%), with CO2 / N2 separation factors ranging from 32.9 to 42.6 and CO2 permeability ranging from 283.9 to 408.1×10 -9 mol·m -2 ·s -1 ·Pa -1 .

[0149] Example 15

[0150] Repeatability test of CO2 / N2 separation performance of flue gas using MIL-140A membrane containing histidine-promoted transport

[0151] Different batches of histidine-facilitated MIL-140A membranes prepared according to the method described in Example 1 were tested sequentially for CO₂ / N₂ mixed gas separation. The test conditions were as follows: 30°C, a 1-bar pressure differential across the membrane, an equimolar feed of the mixed gas, 0% relative humidity, and a helium purge gas.

[0152] The CO2 / N2 separation performances of three different MIL-140A membranes containing histidine-promoted transport are shown in Table 1. The results show that the MIL-140A membrane prepared by the amino acid competitive coordination regulation strategy has excellent performance reproducibility, with CO2 / N2 separation factors ranging from 43.19 to 47.09 and CO2 permeabilities ranging from 101.29 to 171.89×10 -9 mol·m -2 ·s -1 ·Pa -1 .

[0153] Table 1 Separation performance of MIL-140A membrane in CO2 / N2 mixed system

[0154]

[0155] Comparative Example 1

[0156] Preparation of conventional MIL-140A membrane without histidine

[0157] The specific implementation steps are the same as those in Example 1, except that histidine is not added in step (1).

[0158] XRD patterns ( Figure 29 ) shows that all characteristic diffraction peaks of the MIL-140A film prepared in this example completely match the characteristic diffraction peaks of the standard MIL-140A phase, without any other impurity phase. Figure 30 As shown, compared with the histidine-promoted transfer MIL-140A molecular sieve membrane prepared in Example 1, the MIL-140A membrane prepared in this example has poor inter-grain continuity, visible crystal boundary defects, and a thickness of 4 μm; CO2 / N2 mixed gas separation test (tested at 30°C, the pressure difference between the two sides of the membrane is 1 bar, the mixed gas is fed in equimolar amounts, the relative humidity is 0%, and the purge gas is helium) The results show that its CO2 / N2 separation factor is only 12.9, which is far lower than the actual industrial flue gas separation requirements. Therefore, the results of Example 1 show that in the present invention, the use of amino acids as competitive coordination modifiers can effectively inhibit the excessively rapid crystallization reaction of MOF in the bulk phase, thereby precisely regulating the nucleation and growth rates of the MOF film layer on the carrier surface and effectively eliminating the non-selective intergranular boundary defects of the MOF film layer.

[0159] Comparative Example 2

[0160] Preparation of conventional UiO-66 membrane without histidine

[0161] The specific implementation steps are the same as those in Example 2 and Example 3, except that histidine is not added in step (1) of Example 2 and Example 3.

[0162] Conventional UiO-66 film plane and cross-section SEM Figure 31 As shown: the film surface is relatively continuous and the film thickness is 5μm. XRD spectrum ( Figure 32 ) showed that all its characteristic diffraction peaks completely matched those of the standard UiO-66 phase, without any other impurity phases. The results of the CO2 / N2 mixed gas separation test (tested at 30°C, a pressure difference of 1 bar across the membrane, equimolar feed of the mixed gas, 0% relative humidity, and helium as the purge gas) showed that compared with the UiO-66 molecular sieve membrane containing histidine to promote transport, the conventional UiO-66 membrane had a lower CO2 / N2 separation factor and a higher CO2 permeability. Its CO2 / N2 separation factor was 22.5, and the CO2 permeability was 607.9×10 -9 mol·m -2 ·s -1 ·Pa -1Calculations also show that conventional UiO-66 membranes have larger micropore diameters and lower CO2 / N2 diffusion selectivity, meaning they have lower CO2 and N2 screening capabilities. Therefore, the results of Comparative Example 2 demonstrate that, in the present invention, amino acids can coordinate with the zirconium-oxygen cluster nodes of the MOF framework, firmly embedding them within the framework. This effectively modulates the size and shape of the MOF membrane's mass transfer channels, achieving more precise CO2 screening.

[0163] Comparative Example 3

[0164] Conventional UiO-66 membrane CO2 / N2 separation performance test in flue gas under a wide humidity range (relative humidity 0-100%)

[0165] The conventional UiO-66 membrane prepared in Comparative Example 2 was tested for CO₂ / N₂ mixed gas separation at various relative humidities. The test conditions were as follows: 30°C, a 1-bar pressure differential across the membrane, an equimolar feed of the mixed gas, and a pre-flow of the mixed gas through a steam generator before entering the membrane module to control the relative humidity of the feed gas. Helium was used as the purge gas.

[0166] Under the condition of 50% relative humidity, the CO2 / N2 separation factor of the conventional UiO-66 membrane decreased by about 72.5% and the CO2 permeability decreased by about 92.9% compared with the dry separation. Under the condition of 100% relative humidity, the conventional UiO-66 membrane almost completely lost its CO2 / N2 separation ability and the CO2 permeability decreased by 99.9%, indicating that its microporous mass transfer channels were almost completely blocked by H2O molecules that competed with CO2 for adsorption, while the UiO-66 molecular sieve membrane containing histidine to promote transfer showed a more excellent CO2 / N2 separation performance at this humidity. Therefore, the results of Comparative Example 3 show that in the present invention, the amino acids with strong CO2 absorption capacity and excellent reaction kinetics embedded in the skeleton can be used as active carriers to undergo reversible nucleophilic addition reaction with CO2 and H2O, so that CO2 is chemically adsorbed in the form of carbamate ions or bicarbonate ions and undergoes ultra-high-speed transmembrane diffusion, thereby achieving a significant improvement in CO2 separation performance under high humidity environment.

[0167] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0168] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers, characterized in that: A reaction precursor solution is obtained by sequentially adding a metal source, an organic ligand and an amino acid to a mixed solution containing a solvent and a regulator and dissolving them. Subsequently, a dense amino acid-promoting metal-organic framework membrane is prepared on a porous carrier using an in situ growth method or a seed crystal method under solvent thermal conditions.

2. The method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers according to claim 1, characterized in that: The molar ratio of the amino acid to the organic ligand is 1:0.1-10, and the molar ratio of the amino acid to the metal source is 1:0.1-10.

3. The method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers according to claim 1, characterized in that: The specific steps include: (1) After uniformly mixing the solvent and the regulator, a metal source, an organic ligand, and an amino acid are sequentially added and dissolved to obtain a reaction precursor solution; (2) fixing an unmodified porous support or a porous support coated with metal organic framework seeds and placing it in a reactor, adding the above reaction precursor solution into the reactor, and then performing a solvothermal reaction; (3) After the reaction is completed, a continuous and dense amino acid-promoting metal-organic framework membrane can be obtained through washing and drying.

4. The method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers according to claim 1 or 3, characterized in that: The amino acid is at least one of histidine, arginine, lysine, glycine, alanine, sarcosine, proline, cysteine, valine, leucine, isoleucine, methionine, tryptophan, serine, tyrosine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, selenocysteine, pyrrolysine, citrulline, ornithine and hydroxyproline.

5. The method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers according to claim 1 or 3, characterized in that: The solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, dimethyl sulfoxide, cyclohexane, acetone, water, methanol, ethanol, and propanol; the regulator is at least one of formic acid, acetic acid, hydrochloric acid, nitric acid, benzoic acid, difluoroacetic acid, and trifluoroacetic acid; the metal source is a zirconium-based metal source, a titanium-based metal source, or a zinc-based metal source; and / or, The molar ratio of the metal source to the regulator is 1:10-5000, and the molar ratio of the metal source to the solvent is 1:10-5000.

6. The method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers according to claim 1 or 3, characterized in that: The metal organic framework membrane and the corresponding organic ligands are as follows: terephthalic acid corresponding to MIL-140A, UiO-66 and MIL-125; 2,6-naphthalene dicarboxylic acid corresponding to MIL-140B; 2-aminoterephthalic acid corresponding to UiO-66-NH2; nitroterephthalic acid corresponding to UiO-66-NO2; 2,5-dihydroxyterephthalic acid corresponding to UiO-66-(OH)2; UiO-66-C H3 corresponds to 2-methylterephthalic acid; UiO-66-Br corresponds to 2-bromotetrabenzoquinone; MIL-140C and UiO-67 correspond to 4,4'-biphenyldicarboxylic acid; UiO-68 corresponds to terphenyldicarboxylic acid; UiO-66-1,4-Naph corresponds to 1,4-naphthalene dicarboxylic acid; MOF-801 corresponds to fumaric acid; MOF-802 corresponds to 1H-pyrazole-3,5-dicarboxylic acid; MOF-805 corresponds to 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid; 3,3'-dihydroxy-4,4'-biphenyldicarboxylic acid corresponding to MOF-806; 1,3,5-benzenetricarboxylic acid corresponding to MOF-808; 4,4',4",4"'-tetramethyltetrabenzoic acid corresponding to MOF-812 or MOF-841; 1,3,6,8-tetra(p-benzoate)pyrene corresponding to NU-1000; PCN-221, PCN-222, PCN- meso-tetrakis(4-carboxyphenyl)porphyrin corresponding to PCN-223, PCN-224 or PCN-225; 2,6-naphthalenedicarboxylic acid corresponding to DUT-52 or DUT-84; 2,5-thiophenedicarboxylic acid corresponding to DUT-67, DUT-68 or DUT-69; 9,10-anthryldibenzoic acid corresponding to Zr-ADC; 5,5'-methylenediisophthalic acid corresponding to MIP-177; 2-methylimidazole corresponding to ZIF-8.

7. The method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers according to claim 3, characterized in that: The metal organic framework seed crystals described in step (2) are prepared by washing and centrifuging a reaction precursor solution after liquid phase reaction; the dispersant of the metal organic framework seed crystal solution is at least one of methanol, ethanol, propanol, butanol and water; the concentration of the seed crystal solution is 0.01% to 10wt.%; the seed crystal coating method is spin coating, dip coating, spray coating, wipe coating or interfacial self-assembly; and / or, The solvent thermal reaction heating method in step (2) is convection heating or microwave heating, and the heating time is 1 minute to 120 hours; the convection heating is oven heating or oil bath heating, and the microwave heating is single-mode microwave heating or multi-mode microwave heating.

8. The method for preparing a metal-organic framework membrane using amino acids as CO2 active carriers according to claim 1 or 3, characterized in that: The type of the porous carrier is flat plate, tubular, coiled or hollow fiber; the type of the porous carrier is porous metal oxide, porous metal or porous non-metal oxide; the porous metal oxide is porous alumina, porous titanium oxide or porous yttrium oxide, the porous metal is porous stainless steel or porous nickel, and the porous non-metal oxide is porous silicon oxide, porous silicon carbide or porous glass.

9. Use of the amino acid-promoted metal organic framework membrane obtained by the method of claim 1 in separating CO2 from flue gas in an industrial wide humidity range.

10. Use of the amino acid-promoted metal organic framework membrane for CO2 separation from flue gas in an industrial wide humidity range environment as claimed in claim 9, characterized in that: The flue gas CO2 separation system is CO2 / N2, CO2 / H2 or CO2 / CH4; the relative humidity range of the separation environment is 0-100%.

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