Use of an aluminiferous metal organic framework material

Abstract

The application relates to the field of adsorption separation technology, in particular to application of an aluminum-based metal organic framework material. The application of the aluminum-based metal organic framework material in the field of adsorption is characterized in that the chemical formula of the aluminum-based metal organic framework material is: [Al 24 (OCH3) x (OH) 56‑x (PTA)6](OAc) y Cl 4‑y ; wherein, x =14~35, y =0~1; PTA 2 represents a terephthalate ion, OAc represents an acetate ion; the aluminum-based metal organic framework material takes Al 24 clusters as metal nodes, each Al 24 cluster is connected with 12 carboxyl groups from PTA 2 , and each PTA 2 is connected with 2 Al 24 clusters. The material has high crystallinity, high chemical stability and high thermal stability, and has significant application potential in the fields of wastewater treatment, gas adsorption and separation.

Description

Technical Field

[0001] This application relates to the field of adsorption separation technology, and in particular to the application of an aluminum-based metal-organic framework material. Background Technology

[0002] Metal-organic frameworks (MOFs), as a new class of crystalline porous materials, possess a rich variety of morphologies and structures, and have wide applications in fields such as gas adsorption and water treatment. Compared with other transition metal-based MOF materials, aluminum-based MOF materials generally have advantages such as low cost, light weight, low toxicity, and good stability, making them suitable for long-term, recyclable, and interference-resistant environmental applications such as adsorption of heating or cooling gases, energy storage gases, and CO2 adsorption. In particular, aluminum-based MOF materials synthesized from inexpensive and readily available organic ligands (such as formic acid, 2-methylimidazole, terephthalic acid, and 1,3,5-benzenetricarboxylic acid) are considered more suitable for industrial applications.

[0003] Due to the diversity of aluminum ion coordination modes, novel aluminum-based MOF materials can be constructed from different secondary building units (SBUs), including single aluminum ions, structurally oriented aluminum oxide clusters, and one-dimensional (1D) chains. Among these, aluminum oxide clusters include zero-dimensional (0D) Al3 clusters, Al8 clusters, and Al... 12 Clusters and Al 24 cluster. Al 24 A cluster is a special type of group of clusters that has O h It exhibits symmetry and cationic properties, and possesses high structural, chemical, and thermal stability. Unlike neutral aluminum-based SBU, it incorporates Al... 24 When aluminum-based MOF materials are formed by clustering and networking, they will inherit the properties of Al. 24 The cationic properties of the clusters. It is noteworthy that ionic aluminum-based MOF materials are significantly scarce compared to neutral aluminum-based MOF materials. In addition, Al... 24 Clusters are also an ideal platform for constructing aluminum-based MOF materials with various topologies. It is speculated that, similar to the well-known Zr6 clusters, Al... 24 Clusters can also be connected into network structures with different coordination numbers (ranging from 4 to 12), which mainly depends on the ligands and synthesis conditions.

[0004] However, traditional techniques have not yet synthesized materials containing Al. 24 Clustered aluminum-based MOF materials (abbreviated as Al) 24 -MOF materials, whose potential applications in the field of adsorption have not yet been explored and realized. Summary of the Invention

[0005] Therefore, it is necessary to provide an application of aluminum-based metal-organic framework materials in the field of adsorption, as traditional technologies lack aluminum-containing materials. 24 The problem is that aluminum-based MOF materials with clusters cannot realize their application potential in the field of adsorption.

[0006] The above-mentioned objective of this application is achieved through the following technical solution: This application provides an application of an aluminum-based metal-organic framework material in the field of adsorption, wherein the chemical formula of the aluminum-based metal-organic framework material is: [Al 24 (OCH3) x (OH) 56 x (PTA)6](OAc) y Cl4 y ; in, x = 14~35, y = 0~1; PTA 2 OAc represents the terephthalate ion. This represents the acetate ion; The aluminum-based metal-organic framework material is based on Al 24 The cluster is a metallic node, each of the Al nodes 24 Clusters and 12 from PTA 2 The carboxyl groups are linked together, each PTA 2 With the two Al 24 Clusters are connected.

[0007] In one embodiment, the application includes: A mixture is provided in which the concentration of hexavalent chromium is 0.5 ppm to 400 ppm; The mixture was subjected to adsorption treatment using the aluminum-based metal-organic framework material to ensure that the concentration of hexavalent chromium was ≤ 0.1 ppm. The aluminum-based metal-organic framework material after adsorption treatment is washed sequentially with NaCl solution and water to regenerate it.

[0008] In one embodiment, the adsorption treatment includes the following steps: The aluminum-based metal-organic framework material is dispersed in the mixture and then allowed to stand, stirred, or sonicated. or, The aluminum-based metal-organic framework material and inorganic packing material are packed into a chromatographic column at a mass ratio of 1:(50~60), and the mixture is allowed to flow through the chromatographic column at a flow rate of 10 mL / min~50 mL / min.

[0009] In one embodiment, the application includes: The aluminum-based metal-organic framework material is used to adsorb and treat a mixed gas containing propylene and ethylene to capture propylene in the mixed gas. The aluminum-based metal-organic framework material after adsorption treatment is desorbed using a protective gas to recover the captured propylene.

[0010] In one embodiment, one or more of the following conditions are met: (1) Prior to the adsorption treatment, the method further includes the following step: converting the counter anion of the aluminum-based metal-organic framework material into Cl... Replaced with Br I SO4 2 and [Fe(CN)6] 3 Any one of them; (2) In the mixed gas, the mass ratio of propylene to ethylene is 1:(1~9); (3) At 298 K and 1 bar, the aluminum-based metal-organic framework material has an adsorption capacity of ≥6 mmol / g for propylene and ≤1.7 mmol / g for ethylene; (4) The protective gas includes any one of nitrogen, helium and argon; (5) The purity of the recovered propylene is ≥99.5%.

[0011] In one embodiment, the application includes: A composite material was prepared by loading polyethyleneimine onto the aluminum-based metal-organic framework material; The composite material is used to adsorb CO2 to enrich CO2.

[0012] In one embodiment, the mass ratio of the polyethyleneimine to the aluminum-based metal-organic framework material is (10~70):100.

[0013] In one embodiment, at 298 K and 1 bar, the composite material adsorbs ≥1.3 mmol / g of CO2. At 298 K and 0.4 mbar, the composite material adsorbs CO2 at a rate ≥0.3 mmol / g.

[0014] In one embodiment, the application includes: The aluminum-based metal-organic framework material was heat-treated in air at 150 ℃~250 ℃. The heat-treated aluminum-based metal-organic framework material is used to adsorb water vapor to enrich it.

[0015] In one embodiment, at 298 K, P / P At a pH of 0 ≈ 0.9, the aluminum-based metal-organic framework material maintains an adsorption capacity of ≥650 mg / g for water vapor; wherein, P / P 0 represents the ratio of the actual pressure of water vapor to the saturated vapor pressure.

[0016] This application has at least the following beneficial effects: This application provides a novel Al 24 - Applications of MOF materials in the field of adsorption, this Al 24 MOF materials are the first to use Al 24 Clusters are metallic nodes, and are represented by PTA. 2 It is an organic ligand. Analysis and testing revealed that this Al... 24 The chemical formula of MOF material is [Al] 24 (OCH3) x (OH) 56 x (PTA)6](OAc) y Cl4 y Each Al 24 Clusters and 12 from PTA 2 The carboxyl group (-COO) Connected to each PTA 2 With 2 Al 24 Clusters connect to form a crystalline porous material with a three-dimensional network structure. This material possesses high crystallinity, high chemical stability, and high thermal stability, demonstrating significant application potential in wastewater treatment, gas adsorption and separation, and other fields. Building upon this, this application further specifically applies this material to the treatment of hexavalent chromium wastewater, highly selective adsorption and separation of ethylene / propylene, efficient capture of carbon dioxide, and water vapor enrichment, exhibiting superior adsorption performance compared to traditional Al-MOF materials such as MIL-53. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 Al in one embodiment 24 - A schematic diagram of the three-dimensional structure and topology of MOF materials.

[0019] Figure 2 The PXRD patterns are of the products from Synthetic Examples 1-2.

[0020] Figure 3 The image shows the fitting result of CCEG-1 after Rietveld refinement.

[0021] Figure 4 This is the FESEM image of CCEG-1.

[0022] Figure 5 CCEG-1 for Cr2O7 2 Adsorption isotherm diagram.

[0023] Figure 6 The adsorption kinetics curve of CCEG-1 on Cr(VI) in a high-concentration Cr(VI) solution is shown.

[0024] Figure 7 The adsorption kinetics curve of CCEG-1 on Cr(VI) in a low concentration Cr(VI) solution is shown.

[0025] Figure 8 The image shows the chromatographic adsorption results of CCEG-1 on Cr(VI) solution; where, Figure 8 Figure (a) shows the UV-Vis spectrum of CCEG-1 after six cycles of treatment with 100 ppm Cr(VI) solution (the inset in the upper left corner shows the photos before and after adsorption treatment), Figure (b) shows the removal rate results of the six cycles of treatment in Figure (a), Figure (c) shows the UV-Vis spectrum of continuous column adsorption treatment using CCEG-1, and Figure (d) shows the column separation detection results corresponding to Figure (c).

[0026] Figure 9 The diagram shows the adsorption-desorption isotherms of CCEG-1 on ethylene and propylene at different temperatures.

[0027] Figure 10 The figure shows the breakthrough test results of CCEG-1 for mixed gases with different volume ratios at 298 K; where, Figure 10 Figures (a), (c), and (e) in the figure are the breakthrough adsorption diagrams for C2H4:C3H6=1:1, C2H4:C3H6=5:2, and C2H4:C3H6=9:1, respectively. Figure 10 Figures (b), (d), and (f) are penetration desorption diagrams for C2H4:C3H6=1:1, C2H4:C3H6=5:2, and C2H4:C3H6=9:1, respectively.

[0028] Figure 11 For different load qualities x PXRD plot of PEI@CCEG-1.

[0029] Figure 12 This is a comparison of the infrared spectra of CCEG-1 before and after loading.

[0030] Figure 13 Figure (a) is the SEM image of 60PEI@CCEG-1, and Figure (b) is the EDS image of 60PEI@CCEG-1.

[0031] Figure 14 The figure shows the nitrogen adsorption isotherms of CCEG-1 at 77 K before and after loading.

[0032] Figure 15 for x CO2 adsorption isotherms of PEI@CCEG-1 under different pressures; where (a) is the CO2 adsorption isotherm at 0~1 bar (high pressure zone) and (b) is the CO2 adsorption isotherm at 0~1 mbar (low pressure zone).

[0033] Figure 16 The images show the CO2 adsorption isotherms of the originally synthesized 60PEI@CCEG-1 and 60PEI@CCEG-1 after being placed in air for 60 days.

[0034] Figure 17 The images show the PXRD patterns of the original synthesized 60PEI@CCEG-1, 60PEI@CCEG-1 after being placed in air for 60 days, and CCEG-1.

[0035] Figure 18 The image shows the ten-round penetration curves of 60PEI@CCEG-1 against CO2 under dry air.

[0036] Figure 19 The images show the PXRD patterns of the original synthesized CCEG-1 and CCEG-1 after heat treatment at different temperatures.

[0037] Figure 20 The figures show nitrogen adsorption isotherms of CCEG-1 and CCEG-1 after heat treatment at different temperatures.

[0038] Figure 21 The image shows the water vapor adsorption isotherms of CCEG-1 and CCEG-1 after heat treatment at different temperatures. Detailed Implementation

[0039] To facilitate understanding of this application, the following detailed description is provided in conjunction with specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] In this application, "and / or" means any and all combinations of one or more of the related listed items. "At least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two, three, etc., unless otherwise expressly and specifically defined. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.

[0042] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0043] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0044] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0045] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0046] In this application, room temperature refers to indoor temperature, normal temperature, or general temperature. Generally, room temperature can be any of the following temperature ranges: 23 ℃ ± 2 ℃, 25 ℃ ± 5 ℃, or 20 ℃ ± 5 ℃.

[0047] the term Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings: Terephthalic acid: also known as 1,4-phthalic acid, with the molecular formula C8H6O4, and its English name is p -phthalic acid, denoted as H₂PTA. Terephthalic acid has two carboxyl groups (-COOH) at the para position. After losing two protons, it forms the terephthalate ion, denoted as PTA. 2 .

[0048] Acetic acid, also known as acetic acid, has the molecular formula CH3COOH. It consists of one acetyl group (CH3CO-, i.e., Ac-) and one hydroxyl group (-OH), and can be written as AcOH or HOAc. After losing a proton, it forms the acetate ion, denoted as OAc. .

[0049] Aluminum-based metal-organic framework materials: also known as aluminum-based MOF materials or Al-MOF materials. Among them, those based on Al... 24 Clustered aluminum-based MOF materials are abbreviated as Al 24 -MOF materials.

[0050] PXRD: Powder X-ray Diffraction.

[0051] FESEM: Field Emission Scanning Electron Microscope.

[0052] Concentration units: ppm represents mg / L (milligrams per liter), ppb represents ug / L (micrograms per liter), 1 ppm = 1000 ppb = 1000000 ppt.

[0053] This application provides a novel Al 24 - Applications of MOF materials in the field of adsorption. Understandably, applications in adsorption include liquid-phase adsorption and gas adsorption. Liquid-phase adsorption includes wastewater treatment, drinking water purification, and water resource recovery, while gas-phase adsorption includes gas separation and purification, removal of gaseous pollutants, CO2 capture, and water vapor enrichment.

[0054] In some embodiments, Al 24 The chemical formula of MOF material is: [Al 24 (OCH3) x (OH) 56-x (PTA)6](OAc) y Cl 4-y ; in, x = 14~38, y = 0~1; PTA 2 OAc represents the terephthalate ion. Represents acetate ion, Cl It belongs to the category of counter anions.

[0055] Al 24 -MOF materials with Al 24 Clusters are metallic nodes, each Al 24 Clusters and 12 from PTA 2 The carboxyl groups are linked together, each pair of PTA 2 With 2 Al 24 Clusters are connected.

[0056] This application provides a novel Al 24 - Applications of MOF materials in the field of adsorption, this Al 24 MOF materials are the first to use Al 24 Clusters are metallic nodes, and are represented by PTA. 2 It is an organic ligand. Analysis and testing revealed that this Al... 24 The chemical formula of MOF material is [Al] 24 (OCH3) x (OH) 56-x (PTA)6](OAc) y Cl 4-y Each Al 24 Clusters and 12 from PTA 2 The carboxyl group (-COO) Connected to each PTA 2 With 2 Al 24 Clusters connect to form a crystalline porous material with a three-dimensional network structure. This material possesses high crystallinity, high chemical stability, and high thermal stability, demonstrating significant application potential in wastewater treatment, gas adsorption and separation, and other fields. Building upon this, this application further specifically applies this material to the treatment of hexavalent chromium wastewater, highly selective adsorption and separation of ethylene / propylene, efficient capture of carbon dioxide, and water vapor enrichment, exhibiting superior adsorption performance compared to traditional Al-MOF materials such as MIL-53.

[0057] Al 24 MOF materials Al 24 The chemical formula of MOF material is: [Al] 24 (OCH3) x (OH) 56-x (PTA)6](OAc) y Cl 4-y .

[0058] Understandably, x This represents the stoichiometric number of the methoxy group (-OCH3). x The constant can be any value between 14 and 38, for example, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, or 38, etc. Preferably, x = 20~32.

[0059] Similarly, 56- x The stoichiometric coefficient of the hydroxyl group (-OH) is represented by 56- x Take any constant between 18 and 42. Preferably, 56- x = 24~36.

[0060] Understandably, y It represents acetate ions (OAc) ) stoichiometric coefficients, y The constant can be any value between 0 and 1, such as 0, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, or 1. Preferably, y = 0~0.5.

[0061] Similarly, 4- y Chloride ions (Cl) ) stoichiometric coefficient, 4- yTake any constant between 3 and 4. Preferably, 4- y = 3.5~4.

[0062] In some embodiments, Al 24 -MOF materials have any one of the following chemical formulas: (1) [Al] 24 (OCH3) 32 (OH) 24 (PTA)6]Cl4; (2) [Al] 24 (OCH3) 24 (OH) 32 (PTA)6]Cl4; (3) [Al] 24 (OCH3) 16 (OH) 40 (PTA)6]Cl4; (4) [Al 24 (OCH3) 16 (OH) 40 (PTA)6]Cl4; (5) [Al] 24 (OCH3) 17 (OH) 39 (PTA)6]Cl4; (6) [Al] 24 (OCH3) 32 (OH) 24 (PTA)6](OAc) 0.4 Cl 3.6 ; (7) [Al] 24 (OCH3) 24 (OH) 32 (PTA)6](OAc) 0.4 Cl 3.6 ; (8) [Al] 24 (OCH3) 16 (OH) 40 (PTA)6](OAc) 0.4 Cl 3.6 ; (9) [Al] 24 (OCH3) 16 (OH) 40 (PTA)6](OAc) 0.8 Cl 3.2 ; (10) [Al] 24 (OCH3) 17 (OH)39 (PTA)6](OAc) 0.4 Cl 3.6 .

[0063] In Al 24 In MOF materials, -OCH3 and PTA 2 The ideal molar ratio is 32:6, as shown in chemical formulas (1) and (6). However, Al... 24 -MOF materials may contain defects and highly disordered bridging oxygen ligands (-OCH3, -OH), which can cause -OCH3 to interact with PTA. 2 The molar ratio deviates from 32:6.

[0064] In some embodiments, Al 24 The cluster is a cationic secondary building unit (SBU) with a cage-like structure. Under ideal conditions without defects and disorder, its chemical formula is: [Al 24 ( μ 2-OCH3) x-8 ( μ 2-OH) 56-x ( μ 3-OCH3)8(COO) 12 ] 4+ .in, x The values ​​of are as described above. x = 14~38, with 20~32 being preferred.

[0065] Similar to the Zr6 cluster in the zirconium-based MOF material UiO-66, such as Figure 1 As shown, the cage-like Al 24 The cluster also has 12 connections from PTA. 2 The carboxyl group (-COO) ). In Al 24 In the cluster, each aluminum ion (Al) 3+ They are all equivalent, both in the octahedral six-coordinate mode, and connected to two... μ 2-OCH3, 2 μ 2-OH, 1 μ 3-OCH3 and 1 from PTA 2 The carboxyl oxygen. Among them, μ 2 indicates a two-connection. μ 3 indicates a triple connection.

[0066] In some embodiments, in Al 24Chloride ions (Cl) are present on each octagonal face of the cluster. ), with a share of 2 / 3, each Cl All with 4 μ The 2-OH groups are hydrogen-bonded with a spacing of 3.05 Å.

[0067] In some embodiments, Al 24 MOF materials have at least two different pore sizes. Al 24 - The intricate interconnections within MOF materials form various pore structures, including tetrahedral cages with a pore size of 1 nm and octahedral cages with a pore size of 1.9 nm.

[0068] In some embodiments, such as Figure 1 As shown, Al 24 -MOF material, referred to as CCEG-1 in this application, crystallizes in a highly symmetric space group. F In 23, there is an fcu topology. Specifically, Al 24 The unit cell parameters of the MOF material are: a = 29.27 Å, b =29.27 Å, c = 29.27Å, α = 90°, β = 90°, γ = 90°, cell volume is 25070 Å 3 .

[0069] In some embodiments, Al 24 - The morphology of the MOF material is octahedral nanocrystal particles, further proving that it crystallizes in the cubic space group.

[0070] In some embodiments, Al 24 - The particle size of the MOF material is 100 nm to 500 nm, for example, it can be 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm, preferably 150 nm to 250 nm.

[0071] In some embodiments, Al 24 - MOF materials have a BET specific surface area ≥ 1500 m² 2 / g, for example, can be 1500 m 2 / g、1550 m 2 / g、1600 m 2 / g、1650 m 2 / g or 1700 m 2 / g.

[0072] In some embodiments, at a temperature of 298 K, Al 24 - The MOF material adsorbs 20 cm⁻¹ of CO₂ at 1 bar pressure. 3 / g ~ 30 cm 3 / g, for example, can be 20 cm 3 / g、22 cm 3 / g、24 cm 3 / g、26 cm 3 / g、28 cm 3 / g or 30 cm 3 / g.

[0073] Preparation method In some embodiments, Al 24 The preparation method of MOF materials includes the following steps: S100: A mixture of aluminum salt, terephthalic acid, organic base, and organic solvent is ultrasonically treated to form a transparent reaction solution; S200: The reaction solution is subjected to heat treatment and purification to obtain Al. 24 -MOF materials; The molar ratio of organic base to terephthalic acid is ≥4.

[0074] In the preparation method provided in this application, based on aluminum salt and terephthalic acid (H2PTA), an appropriate amount of organic base is added to control the molar ratio of organic base to terephthalic acid ≥4, which ensures that the reaction solution exhibits strong alkalinity, thus being beneficial to Al 24 The formation of clusters inhibits the formation of phases such as MIL-53 and CAU-1-PTA that are unstable under alkaline conditions, thereby promoting the reaction to more readily generate Al. 24 -MOF materials. Meanwhile, strong alkaline conditions also favor increasing the reaction rate and regulating the coordination crystallization process, thus enabling the Al... 24 - The crystallinity of MOF materials is significantly improved, thus enabling the directional production of highly crystalline or even single-crystal Al. 24 -MOF materials.

[0075] In some embodiments, the aluminum salt includes one or more of aluminum chloride (AlCl3), aluminum sulfate (Al2(SO4)3) and aluminum nitrate (Al(NO3)3), preferably aluminum chloride (AlCl3).

[0076] In some embodiments, the molar ratio of aluminum to terephthalic acid in the aluminum salt is (3.5~6):1, for example, it can be 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1 or 6:1.

[0077] In some embodiments, the organic base includes triethylamine (Et3N, TEA) or N,N-dimethylformamide (DMF).

[0078] In some embodiments, the organic solvent comprises methanol (MeOH) and acetonitrile (MeCN) in a volume ratio of (1.5~2.5):1. The volume ratio of methanol to acetonitrile is 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, or 5:1.

[0079] In some embodiments, when triethylamine (TEA) is selected as the organic base, the volume ratio of TEA to organic solvent is 1:(8~22); when N,N-dimethylformamide (DMF) is selected as the organic base, the volume ratio of DMF to organic solvent is 1:(75~300).

[0080] In some embodiments, the molar ratio of organic base to terephthalic acid is ≥4 (i.e., 4:1), for example, it can be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, preferably 10 to 12 (i.e., 10:1 to 12:1).

[0081] In some embodiments, the ultrasonic treatment time is 10 min to 60 min, for example, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min; the ultrasonic treatment temperature is 15 ℃ to 40 ℃, for example, 15 ℃, 18 ℃, 20 ℃, 22 ℃, 25 ℃, 28 ℃, 30 ℃, 32 ℃, 35 ℃, 38 ℃ or 40 ℃.

[0082] In some embodiments, the temperature of the heat treatment is 60 ℃ ~ 120 ℃, for example, it can be 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃ or 120 ℃.

[0083] In some embodiments, the heat treatment time is 36 h to 96 h, for example, 36 h, 48 h, 60 h, 72 h, 84 h or 96 h.

[0084] In some embodiments, the heat treatment can be performed under static or reflux conditions.

[0085] In some embodiments, the purification process includes, in sequence, filtration, washing, and drying.

[0086] The filtration process includes conventional filtration, vacuum filtration, or pressure filtration, with vacuum filtration being the preferred method.

[0087] The solvent for the washing treatment includes any one of water, tetrahydrofuran (THF), N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), methanol (MeOH), ethanol (EtOH), isopropanol ( i -PrOH), acetonitrile (MeCN), ethyl acetate (EA), acetone, dimethyl sulfoxide (DMSO), 1,4-dioxane and dichloromethane (DCM).

[0088] In some embodiments, after the filtration treatment, the method further comprises the following step: performing immersion treatment with an immersion solution having a pH of 2 to 12 to remove impurities from the reaction mixture and improve the purity of the product.

[0089] Wherein, the pH of the immersion solution is 2 to 12, for example, it can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. The immersion solution comprises an inorganic acid, an organic acid, an inorganic base or an organic base. The inorganic acid comprises HCl, HNO3 or H2SO4; the organic acid comprises acetic acid (CH3COOH), formic acid (HCOOH) or trifluoroacetic acid (TFA); the inorganic base comprises NaOH, KOH, Na2CO3, NaHCO3, K2CO3 or KHCO3; the organic base comprises pyridine, triethylamine (TEA), diethylamine (DEA) or methanolamine (HO-CH2-NH2). Preferably, an alkaline immersion solution is used for the immersion treatment, that is, 7 < pH ≤ 12. Thereby, it can prevent the acidic immersion solution from washing away part of the product while removing impurities, ensuring the output and yield.

[0090] In some embodiments, Al 24 -MOF materials further comprise an activation treatment before application. Wherein, the activation treatment comprises the following steps: dispersing Al 24 -MOF material in an organic solvent, refluxing at 70 °C to 90 °C for 1 day to 2 days, repeating 2 to 3 times for solvent exchange, and vacuuming the obtained solid at 120 °C to 150 °C for 12 h to 24 h to complete the activation. The organic solvent in the activation treatment comprises methanol, ethanol, acetonitrile or acetone.

[0091] application In a first aspect, the present application provides Al 24 -MOF material for use in hexavalent chromium removal.

[0092] Hexavalent chromium (Cr(VI)) is an oxidant widely used in industries such as leather, textiles, electroplating, and organic synthesis. Due to its toxicity and carcinogenicity, the discharge of hexavalent chromium-containing waste during industrial production processes requires strict control, with the permissible limit set at 0.5 ppm according to the Integrated Wastewater Discharge Standard (GB 8978-1996). Besides photocatalytic reduction, electrocatalytic reduction, and reductive precipitation, the main post-treatment method for removing hexavalent chromium is currently ion adsorption, which offers advantages such as ease of operation and high efficiency.

[0093] In some embodiments, Al 24 - Applications of MOF materials in hexavalent chromium removal include: S210: Provides a mixture in which the concentration of Cr(VI) is 0.5 ppm to 400 ppm; S220: Utilizing Al 24 - The MOF material is used to adsorb the mixture to ensure that the concentration of Cr(VI) is ≤ 0.1 ppm; S230: Using NaCl solution and water sequentially to adsorb Al after adsorption treatment 24 - The MOF material is washed to regenerate it.

[0094] Understandably, mixed solutions containing hexavalent chromium include, but are not limited to: domestic wastewater, industrial wastewater, drinking water, natural water bodies, salt lake brine and oil and gas field brine, etc. Industrial wastewater can be electroplating wastewater, textile wastewater and lithium battery recycling solution, etc.

[0095] In some embodiments, the content of Cr(VI) in the mixture is 0.5 ppm to 400 ppm, for example 0.5 ppm, 1 ppm, 2 ppm, 5 ppm, 8 ppm, 10 ppm, 20 ppm, 50 ppm, 80 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 400 ppm, preferably 1 ppm to 42 ppm.

[0096] In traditional technologies, wastewater with relatively low chromium concentrations (below 1000 ppb) is not easily treated by conventional methods such as reduction precipitation. Conversely, when the Cr(VI) concentration is low, Al... 24 MOF materials still exhibit rapid exchange kinetics, enabling Cr(VI) concentrations in wastewater to reach below 0.1 ppm. Therefore, this application provides a method for enriching trace hexavalent chromium, which is of great significance for wastewater treatment and drinking water evolution.

[0097] In some embodiments, the pH value of the mixture is 4 to 10, for example, it can be 4, 5, 6, 7, 8, 9 or 10, preferably 6 to 8.

[0098] In some embodiments, Al 24 -MOF materials for Cr2O7 2- The adsorption capacity is 100 mg / g to 120 mg / g, for example, 100 mg / g, 102 mg / g, 105 mg / g, 108 mg / g, 110 mg / g, 112 mg / g, 115 mg / g, 118 mg / g, or 120 mg / g. Specifically, Al 24 -MOF materials for Cr2O7 2- The maximum adsorption capacity is 6.37 mol / cell, which is equivalent to 108 mg / g.

[0099] In some embodiments, Al 24 - The amount of MOF material used is 0.01 mg / mL to 10 mg / mL, for example 0.01 mg / mL, 0.05 mg / mL, 0.1 mg / mL, 0.2 mg / mL, 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 5 mg / mL, 8 mg / mL or 10 mg / mL.

[0100] In some embodiments, the adsorption treatment in step S220 includes the following steps: S221: Al 24 - The MOF material is dispersed in a mixture and then allowed to stand, stir, or sonicate; or... S222: Al 24 - MOF material and inorganic packing material are packed into the chromatographic column at a mass ratio of 1: (50~60), and the mixture is flowed through the chromatographic column at a flow rate of 10 mL / min~50 mL / min.

[0101] Through adsorption treatment, the removal rate of Cr(VI) in the mixture is ≥49%, preferably ≥90%. 24 -MOF materials exhibit rapid enrichment of Cr(VI), reaching 90% saturation adsorption within minutes and equilibrium after two hours, with a removal rate exceeding 49%. Regarding coexisting ions in the mixed solution, the presence of halide anions (Cl...)... ,Br I Under the interference of SO42-, the removal rate of Cr(VI) can reach over 90%, while the removal rate of oxy-containing anions (SO42-) can be reduced. 2 CO3 2 It has a relatively small impact on the removal of hexavalent chromium.

[0102] In some embodiments, the concentration of the NaCl solution in step S230 is 4 mol / L to 6 mol / L, and the washing process can be performed once or multiple times. 24 - The adsorption of Cr(VI) by MOF materials mainly occurs through ion exchange, therefore regeneration can be achieved through simple brine washing, and the regenerated Al... 24 The fact that MOF materials can still maintain high crystallinity indicates that they have good cycling stability.

[0103] In some embodiments, in step S222, the inorganic filler includes quartz sand, silica gel, etc., Al 24 - The mass ratio of MOF material to inorganic filler can be 1:50, 1:52, 1:55, 1:58 or 1:60.

[0104] Al 24 MOF materials are submicron-sized fine crystals. When packed alone in a chromatographic column, their adsorption efficiency is easily affected by material loss and slow water flow. Combining them with inorganic fillers such as quartz sand effectively supports and fixes the material, ensuring continuous water flow within the column. Using column ion exchange, multiple adsorption cycles were performed on wastewater with an initial concentration of 100 ppm, achieving a Cr(VI) removal rate greater than 99%. Continuous adsorption on wastewater with an initial concentration of 1 ppm resulted in an eluent concentration close to 0 ppm, demonstrating its excellent wastewater treatment capabilities.

[0105] Therefore, it is evident that Al, thanks to its excellent crystallinity, thermal stability, chemical stability, and porosity, has significant potential applications in wastewater treatment and environmental remediation. 24 -MOF materials exhibited highly efficient and interference-resistant adsorption capabilities for hexavalent chromium anions within minutes. Meanwhile, Al... 24 - The combination of MOF materials and inorganic fillers for column ion exchange demonstrates good recyclability in treating industrial wastewater of hexavalent chromium at different concentrations, thus highlighting its potential in industrial environmental remediation.

[0106] Secondly, this application provides AI 24 - Application of MOF materials in the adsorption and separation of ethylene / propylene (C2H4 / C3H6).

[0107] In some embodiments, Al 24 - Applications of MOF materials in the adsorption and separation of C2H4 / C3H6 include: S320: Utilizing AI 24 - MOF materials are used to adsorb and treat mixed gases containing C3H6 and C2H4 to capture propylene in the mixed gases; S330: Using a protective gas to adsorb Al after adsorption treatment 24- The MOF material is desorbed to recover the captured C3H6.

[0108] In some embodiments, prior to step S320, the following steps are also included: S310: Al 24 -MOF materials counteract anions through Cl Replaced with Br I SO4 2 and [Fe(CN)6] 3 Any one of them.

[0109] In some embodiments, the substitution method in step S310 is: to replace Al 24 -MOF material (counter anion is Cl) The Al atoms were immersed in an aqueous solution containing the target anion, ultrasonically dispersed, and stirred at room temperature for one day. Then, they were sequentially centrifuged, washed, solvent-displaced, and activated to obtain Al atoms with different counter anions. 24 -MOF materials.

[0110] The aqueous solution containing the target anion can be NaBr, KBr, NaI, KI, Na₂SO₄, K₂SO₄, Na₃[Fe(CN)₆], or K₃[Fe(CN)₆], etc. The concentration of the anion can be 1 mmol to 10 mmol, for example, 1 mmol, 2 mmol, 5 mmol, 8 mmol, or 10 mmol. 24 - The mass-to-volume ratio of MOF material to aqueous solution is 5 mg / mL to 20 mg / mL, for example, 5 mg / mL, 8 mg / mL, 10 mg / mL, 12 mg / mL, 15 mg / mL, 18 mg / mL or 20 mg / mL.

[0111] In some embodiments, the mass ratio of C3H6 to C2H4 in the mixed gas is 1:(1~9), for example 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2 or 1:1.

[0112] In some embodiments, at 298 K, 1 bar, Al 24 - The MOF material has an adsorption capacity of ≥6 mmol / g for C3H6, preferably 6 mmol / g to 8 mmol / g; and an adsorption capacity of ≤1.7 mmol / g for C2H4, preferably 1.5 mmol / g to 1.7 mmol / g. Specifically, when Al 24 The counter anion of MOF materials is Cl. ,Br I SO4 2 Or [Fe(CN)6] 3 Any one of them, Al 24 - The adsorption capacity of MOF materials for C3H6 remained between 6.3 mmol / g and 7.3 mmol / g, Al 24 - The adsorption capacity of MOF materials for C2H4 remained between 1.52 mmol / g and 1.66 mmol / g.

[0113] In some embodiments, based on the adsorption isotherm at 298 K, calculations using the ideal adsorption solution theory (IAST) show that Al 24 - The adsorption selectivity of MOF materials for C3H6 is ≥6, preferably 6.3~6.6.

[0114] In some embodiments, the protective gas includes any one of nitrogen, helium, and argon, preferably helium.

[0115] In some embodiments, the desorption process in step S320 satisfies the following: the flow rate of the protective gas is 1 mL / min to 10 mL / min, for example, 1 mL / min, 2 mL / min, 5 mL / min, 8 mL / min or 10 mL / min.

[0116] In some embodiments, the recovered purity of C3H6 is ≥99.5%, preferably 99.9%. Here, 99.5% purity is polymer grade, meeting the standard for synthesis of polypropylene, indicating that Al... 24 -MOF materials have excellent separation and purification capabilities for C3H6.

[0117] Thirdly, this application provides AI 24 - Application of MOF materials in CO2 capture.

[0118] In some embodiments, Al 24 - Applications of MOF materials in CO2 capture include: S410: Polyethyleneimine (PEI) is loaded onto Al 24 -MOF materials were used to prepare composite materials; S420: CO2 is enriched by adsorbing CO2 using composite materials.

[0119] In some embodiments, PEI is loaded onto Al 24The method for MOF materials is as follows: S411: Dissolve PEI in methanol to obtain a PEI solution; S412: Add activated Al to PEI solution 24 - MOF material, stirred at room temperature for 1 h to 10 h; S413: The methanol in the mixture is removed by vacuum distillation to obtain the composite material, namely Al loaded with PEI. 24 -MOF materials.

[0120] In some embodiments, PEI and Al 24 - The mass ratio of MOF materials is (10~70):100, for example 10:100, 20:100, 30:100, 40:100, 50:100, 60:100 or 70:100, preferably 60:100.

[0121] In some embodiments, at 298 K and 1 bar, the composite material adsorbs CO2 at a concentration ≥1.3 mmol / g, such as 1.3 mmol / g, 1.5 mmol / g, 1.7 mmol / g, 1.8 mmol / g, 1.9 mmol / g, 2 mmol / g, 2.1 mmol / g, or 2.2 mmol / g, preferably 1.5 mmol / g to 2.1 mmol / g.

[0122] In some embodiments, at 298 K and 0.4 mbar, the composite material adsorbs CO2 at a concentration ≥0.3 mmol / g, for example 0.3 mmol / g, 0.4 mmol / g, 0.5 mmol / g, 0.6 mmol / g, 0.7 mmol / g, 0.8 mmol / g or 0.9 mmol / g, preferably 0.3 mmol / g to 0.8 mmol / g.

[0123] In some embodiments, the working temperature range for CO2 enrichment of the composite material is 298 K to 313 K.

[0124] Fourthly, this application provides Al 24 - Application of MOF materials in water vapor enrichment.

[0125] In some embodiments, Al 24 - Applications of MOF materials in water vapor enrichment include: S510: For Al in air atmosphere at 150℃~250℃ 24 - MOF materials undergo heat treatment; S520: Utilizing heat-treated Al 24-MOF materials are used to adsorb water vapor to enrich it.

[0126] In some embodiments, the heat treatment temperature is 150 ℃ to 250 ℃, for example 150 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃, 240 ℃ or 250 ℃.

[0127] In some embodiments, at 298 K, P / P When 0 ≈ 0.9, Al 24 The MOF material maintains an adsorption capacity for water vapor of ≥650 mg / g, such as 650 mg / g, 680 mg / g, 690 mg / g, 700 mg / g, 720 mg / g, 740 mg / g, 750 mg / g, 780 mg / g, or 800 mg / g, preferably 690 mg / g to 780 mg / g. P / P 0 represents the ratio of the actual pressure of water vapor to the saturated vapor pressure.

[0128] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0129] Synthesis example 1 Al in this synthetic example 24 -MOF materials are prepared using the following method: Methanol (10.5 mL) and acetonitrile (4.5 mL) were mixed to obtain 15 mL of organic solvent. Aluminum chloride hexahydrate (840 mg), terephthalic acid (96 mg), and triethylamine (840 μL) were dissolved in the organic solvent to obtain a mixture. The mixture was sonicated at room temperature for 30 min to form a clear reaction solution. The reaction was carried out at 80 °C for 2 days. The resulting mixture was filtered to obtain a solid, which was then washed with DMF and methanol and dried to obtain a white powder product, designated CCEG-1. The yield of CCEG-1 was measured to be 188 mg, and the yield was calculated to be 65% based on H2PTA.

[0130] In this embodiment, the volume ratio of methanol to acetonitrile is 7:3; The molar ratio of aluminum to terephthalic acid in aluminum chloride hexahydrate is 6:1. The molar ratio of triethylamine to terephthalic acid is 10.3:1; The volume ratio of organic base to organic solvent is 1:17.9.

[0131] Synthesis example 2 The difference between this synthesis example and Synthesis Example 1 is that the molar ratio of triethylamine to terephthalic acid is 3:1, and the resulting product is denoted as MIL-53.

[0132] Test case The products of Synthetic Examples 1 and 2 were subjected to PXRD analysis using a Rigaku MiniFlex 600 X-ray diffractometer. The results are shown in the figure. Figure 2 .in, Figure 2 Al in 24 The simulated PXRD curves for both MOF materials and MIL-53 were obtained through crystal structure analysis. For example... Figure 2 As shown, after interacting with Al 24 The comparison of simulated PXRD curves of MOF materials shows that the synthesis example 1 did indeed produce Al-based materials. 24 Al clusters 24 -MOF material, and without the characteristic peaks of MIL-53, belongs to pure phase Al. 24 -MOF material. No Al was found in the product of synthesis example 2. 24 The characteristic peaks of the MOF material demonstrate that controlling the molar ratio of organic base to terephthalic acid ≥ 4 is crucial for the synthesis of Al. 24 - A key condition for MOF materials is the insufficient amount of organic base, which makes it difficult to effectively suppress the formation of isomers and thus prevents the synthesis of Al. 24 -MOF materials.

[0133] PXRD analysis was performed on CCEG-1, the product of Synthesis Example 1, and the structural model of CCEG-1 was refined using Rietveld. The results are shown in [Figure Number]. Figure 3 .like Figure 1 and Figure 3 As shown, CCEG-1 crystallizes in a highly symmetric space group. F In 23, there is an fcu topological structure with the following cell parameters: a = b = c = 29.2675(7) Å, α = β = γ = 90°, unit cell volume V = 25070.2(18) Å 3 Variance factor of the refined fit R p = 6.93% and weighted variance factor R wp = 9.83%.

[0134] CCEG-1 was characterized using a ZEISS Gemini 300 field emission scanning electron microscope (FESEM). Figure 4 As shown, CCEG-1 has the morphology of octahedral nanocrystal particles with a particle size of approximately 200 nm, which further demonstrates that CCEG-1 crystallizes in the cubic space group.

[0135] Based on NMR and elemental analysis, the molar ratio of methoxy (-OCH3) to terephthalic acid in CCEG-1 is 17.36:6, the atomic percentage of carbon is 25.71%, and the atomic percentage of hydrogen is 4.13%. Therefore, its actual molecular formula should be: [Al 24 (OCH3) 17 (OH) 39 (PTA)6](OAc) 0.4 Cl 3.6 .

[0136] Application Example 1 This application example demonstrates the use of CCEG-1 in the removal of hexavalent chromium.

[0137] (1) Quantitative analysis method: Referring to the modified diphenylcarbazide spectrophotometric method described in GB / T 7467-1987 Determination of Hexavalent Chromium in Water by Diphenylcarbazide Spectrophotometric Method, the low concentration of dichromate was quantitatively analyzed by ultraviolet-visible spectrophotometry: 0.5 mL of sulfuric acid (50 V / V%), 0.5 mL of phosphoric acid (50 V / V%), and 2 mL of colorimetric reagent were added to 25 mL of dichromate-containing solution sample to obtain a mixed solution; wherein, the colorimetric reagent was prepared by dissolving 0.2 g of diphenylcarbazide in 50 mL of acetone and then diluting it with water to 100 mL. The mixed solution was allowed to stand at room temperature for 10 min, and then measured by ultraviolet-visible spectrophotometer, and the Cr2O7 in the mixed solution was calculated. 2 Or the concentration of Cr(VI).

[0138] (2) Adsorption isotherm: 10 mg of activated CCEG-1 was used as the adsorbent and dispersed in 3 mL of K2Cr2O7 aqueous solution (concentration range 0.5 ppm~400 ppm, calculated based on Cr element) and placed in a centrifuge tube. After standing for 12 h, the K2Cr2O7 aqueous solution was separated from the adsorbent, and the residual Cr(VI) concentration was determined by UV-Vis spectrophotometry. Equilibrium adsorption capacity ( Q e Calculate using the following formula: Q e =( C 0 C e ) V ,in, C 0 (ppm) and C e (ppm) represent the initial and equilibrium concentrations of Cr(VI), respectively. V (L) represents the volume of the solution. m (g) represents the mass of the adsorbent. Q e The adsorption amount of Cr(VI) at equilibrium (mg / g) is given. The adsorption isotherm was fitted using the Langmuir adsorption model, and the adsorption capacity of CCEG-1 can be calculated using the following formula: Q e = Q m × C e × K L / (1+ C e × K L ),in, Q m This refers to the monolayer adsorption capacity (mg / g). K L Here is the Langmuir constant (L / mg). The fitting results are shown below. Figure 5 .exist Figure 5 middle, Q e = 0.194 C e / (1+0.0305 C e ) is the fitting function for the adsorption isotherm, and the coefficient of determination is... R 2 =0.982. From Figure 5 The maximum monolayer adsorption capacity obtained by fitting Q m = 6.37 mol / cell (based on Cr2O7) 2 (Calculation), unit-cell refers to the unit cell, that is, CCEG-1 of the unit cell for Cr2O7. 2 The maximum adsorption capacity is 6.37 mol.

[0139] (3) Adsorption kinetics of high-concentration Cr(VI) solution (42 ppm): 10 mg of activated CCEG-1 was dispersed in 3 mL of K2Cr2O7 aqueous solution and placed in a centrifuge tube. The centrifuge tube was then placed in a stirrer in the dark. The changes in K2Cr2O7 concentration after 5 min, 10 min, 30 min, 60 min, 120 min and 240 min were monitored by UV-Vis spectroscopy. The initial concentration of K2Cr2O7 was 120 ppm (equivalent to 42 ppm Cr(VI)). The results are shown in […]. Figure 6 .like Figure 6 As shown, the adsorption of Cr(VI) reaches equilibrium within 60 min, and its adsorption kinetics conform to pseudo-second-order reaction kinetics, with a kinetic constant of approximately 0.14 g mg. 1 min 1 .

[0140] (4) Adsorption kinetics of low-concentration Cr(VI) solution (1 ppm): 5 mg of activated CCEG-1 was dispersed in 25 mL of K2Cr2O7 aqueous solution and placed in a centrifuge tube. The centrifuge tube was then placed in a stirrer in a dark environment. The changes in K2Cr2O7 concentration after 1 min, 2 min, 5 min, 10 min, 20 min, 30 min and 60 min were monitored by UV-Vis spectroscopy. The results are shown in […]. Figure 7 .

[0141] Cr(VI) mainly exists as Cr2O7 2 It exists in the form of a strong oxidizing agent and is therefore widely used in industries such as leather, textiles, electroplating, and organic synthesis. Due to its toxicity and carcinogenicity, the emission limits for Cr(VI) are typically limited to 0.1 ppm or 0.5 ppm (corresponding to...). Figure 7 (The blue and orange dashed lines in the text) are used to strictly control the emission of Cr(VI)-containing waste during industrial processes. For example... Figure 7 As shown, CCEG-1 can still achieve rapid capture even under low concentration Cr(VI) (1 ppm) conditions, reducing the hexavalent chromium concentration to <0.5 ppm within 1 min and further to <0.1 ppm within 30 min.

[0142] (5) Column adsorption: Cotton is packed into the bottom of the chromatographic column (5 cm in diameter and 30 cm in length), and then a mixture of 50 g of quartz sand, 1 g of CCEG-1 and 300 mL of deionized water is poured into the column. The column is then compacted using an air pump to form a dense layer, thus completing the column packing and making a simple CCEG-1 filter device.

[0143] Adsorption of high-concentration Cr(VI) solution (100 ppm) onto a chromatographic column: 100 mL of K₂Cr₂O₇ solution (100 ppm Cr(VI)) was injected into the column and flowed through it at an average flow rate of ~25 mL / min. The filtrate was collected in a beaker and analyzed by UV-Vis spectroscopy. Each flow of 100 mL of K₂Cr₂O₇ solution constituted one adsorption cycle. After each cycle, 5 mol / L NaCl aqueous solution and deionized water were sequentially passed through the column until the filtrate became colorless, thus completing the regeneration of the adsorbent. Figure 8 As shown in Figure (a), a yellow, high-concentration Cr(VI) solution, after adsorption by the chromatographic column, yields a colorless, clear solution. The spectral curve of the K₂Cr₂O₇ solution before adsorption exhibits a clear absorption peak. However, after six consecutive adsorption cycles using the same column, the spectral curve of the resulting filtrate shows no absorption peaks, indicating that Cr(VI) is almost undetectable. Figure 8 As shown in Figure (b), even after 6 adsorption cycles, the removal rate of Cr(VI) still exceeds 99%.

[0144] Column adsorption of low-concentration Cr(VI) solution (1 ppm): A K₂Cr₂O₇ solution (1 ppm Cr(VI)) was injected into the column and allowed to flow through it. The filtrate was collected every 50 mL using a graduated cylinder, and UV-Vis spectroscopy was performed to determine the Cr(VI) concentration of the filtrate. The total volume of K₂Cr₂O₇ solution flowing through the column was divided by the mass of CCEG-1 in the column to calculate the purified amount of CCEG-1, thus measuring its purification capacity. For example, if a column was packed with 1 g of CCEG-1, and 2 L of K₂Cr₂O₇ solution was filtered, resulting in a Cr(VI) concentration of 0.1 ppm in the filtrate, then under an emission limit of 0.1 ppm, the purified amount of CCEG-1 would be 2 L / g. Figure 8 As shown in Figures (c) and (d), with an initial Cr(VI) concentration of 1 ppm, the purification yield reached 4 L g. - ¹, the Cr(VI) concentration in the eluent was close to 0 ppm. Under emission limits of 0.1 ppm and 0.5 ppm, respectively, yields as high as 6 L g were achieved. - ¹ and 10 L g - ¹The purification capacity. These results demonstrate that the CCEG-1 filtration unit possesses excellent wastewater treatment capabilities even when faced with extremely low concentrations of Cr(VI).

[0145] Application Example 2 This application example demonstrates the use of CCEG-1 in the adsorption separation of ethylene / propylene (C2H4 / C3H6).

[0146] (1) Adsorption-desorption isotherm test: CCEG-1 was dispersed in MeOH and refluxed at 70 °C for 1 day for solvent exchange. This solvent exchange process was repeated three times. The resulting solid was activated under vacuum at 120 °C for 24 h. Then, adsorption-desorption isotherms of C2H4 and C3H6 were measured at 273 K, 298 K, and 313 K. The results are shown in [Figure number missing]. Figure 9 Experiments showed that ethylene and propylene exhibited significant adsorption differences. At 298 K and 1 bar, the adsorption capacity of ethylene was 1.59 mmol / g, while that of propylene reached 7.24 mmol / g.

[0147] according to Figure 9 Based on the adsorption isotherms at 273 K, 298 K, and 313 K, the zero-point adsorption enthalpies of CCEG-1 for propylene and ethylene were calculated to be 25.4 kJ / mol and 24.5 kJ / mol, respectively. Figure 9 The adsorption-desorption isotherm at 298 K was used to calculate the adsorption selectivity of CCEG-1 for mixed gases containing propylene and ethylene in different volume ratios. The results are shown in Table 1. Experiments show that the selectivity is above 6 for different volume ratios of propylene and ethylene (50:50, 20:50, 10:90). This indicates that CCEG-1 has high adsorption selectivity for propylene.

[0148] Table 1. Adsorption selectivity of CCEG-1 at 298 K and 1 bar (2) Penetration test: Breakthrough experiments are used to test the adsorption dynamics of porous materials (such as activated carbon and buffer materials). The test material is placed in an adsorption column, and gas is introduced at a certain flow rate. The gas concentration at the outlet is monitored, and a breakthrough curve (i.e., a time-concentration curve) is plotted to characterize the adsorption saturation process and breakthrough time of the material. The breakthrough time for a particular gas is the time when that gas begins to flow out; a later breakthrough time indicates better adsorption performance of the material for that gas. When a mixed gas is introduced, the separation performance of the material for different gases can be characterized by monitoring the effluent concentrations of each gas at different times.

[0149] At 298 K, breakthrough experiments were conducted on the activated CCEG-1 using mixed gases (ethylene to propylene volume ratios of 1:1, 5:2, and 9:1, with flow rates of 2 mL / min, 2.8 mL / min, and 2 mL / min, respectively). The results are shown in Table 2 and [Table data missing]. Figure 10 . Figure 10 Figures (a), (c), and (e) are breakthrough adsorption diagrams of CCEG-1 for mixed gases with different volume ratios. The horizontal axis represents the total gas outflow (mL / g), and the vertical axis represents the gas concentration ratio. The blue line is the breakthrough adsorption isotherm of ethylene, and the red line is the breakthrough adsorption isotherm of propylene. Figure 10 Figures (b), (d), and (f) in the figure are the breakthrough desorption curves of CCEG-1 for mixed gases with different volume ratios. The horizontal axis represents the total gas outflow (mL / g), and the vertical axis represents the gas flow ratio. The blue line is the breakthrough desorption curve of ethylene, and the red line is the breakthrough desorption curve of propylene.

[0150] As shown in Table 2 and Figure 10 As shown, compared with mixed gases of different volume ratios, the breakthrough time of propylene was delayed by 40 to 90 minutes compared with that of ethylene, indicating that CCEG-1 has a high selective adsorption capacity for propylene. Furthermore, no significant decline in adsorption performance was observed in CCEG-1 after the samples were placed in air for six months, demonstrating good cycling stability.

[0151] High-purity helium gas was introduced into the adsorption column, which was saturated with adsorption, at a flow rate of 5 mL / min. Figure 10 As shown, this operation rapidly desorbs all captured propylene within approximately 70 to 350 minutes. The propylene recovery purity calculated from the desorption curves reaches over 99.5%, indicating that CCEG-1 has excellent separation and purification capabilities for propylene. Furthermore, after being exposed to air for six months, CCEG-1 maintains its separation performance for C2H4 / C3H6, demonstrating good stability.

[0152] Table 2. Transmission experimental data of CCEG-1 for different gas mixtures (3) Adsorption isotherm tests of CCEG-1 with different counter anions: The counter anion of CCEG-1 in Synthetic Example 1 is Cl. The active anion is aluminum chloride hexahydrate from the raw material. It can be replaced with other counter anions as follows: 0.5 g of activated CCEG-1 was immersed in 40 mL of aqueous solution containing different anions, namely KBr (5 mmol, 0.60 g), NaI (5 mmol, 0.75 g), Na2SO4 (5 mmol, 0.71 g), or K3[Fe(CN)6] (5 mmol, 1.65 g). After ultrasonic dispersion, the mixture was stirred at room temperature for one day. After the reaction was complete, the resulting suspension was centrifuged, and the precipitate was washed with water. The precipitate was dispersed in 300 mL of methanol, refluxed at 70 °C for one day, centrifuged, and washed with methanol. This solvent exchange process was repeated three times. The final solid was degassed under vacuum at 120 °C for one day to complete activation, thus obtaining activated CCEG-1 with different counter anions.

[0153] The activated material was subjected to adsorption-desorption isotherms of C2H4 and C3H6 at 298 K, and the adsorption capacities of CCEG-1 with different counter anions for C2H4 and C3H6 were calculated. The results are shown in Table 3. As shown in Table 3, different counter anions have little effect on the separation performance, and all can achieve the adsorption separation of ethylene / propylene.

[0154] Table 3. Adsorption capacity of CCEG-1 with different counter anions for C2H4 and C3H6 Application Example 3 This application example demonstrates the use of CCEG-1 in CO2 capture.

[0155] (1) Synthesis of PEI@CCEG-1: Will x 10 mg of PEI was dissolved in 10 mL of methanol and stirred for 30 min until a homogeneous solution was obtained. Then, 100 mg of activated CCEG-1 was added. The mixture was stirred at room temperature for 4 hours, and then the methanol was removed from the mixture by vacuum distillation to obtain the PEI-loaded CCEG-1 composite material, labeled as [label missing]. x PEI@CCEG-1 ( x This represents the mass of PEI loaded on 100 mg of CCEG-1. x =0, 5, 10, 20, 50, 55, 60, 65, 70, 75, 100).

[0156] (2) Characterization of PEI@CCEG-1 right x PXRD testing was performed on PEI@CCEG-1. Figure 11It can be seen that as the PEI loading concentration increases, the composite material can maintain the crystalline state of the CCEG-1 bulk.

[0157] The loading of PEI was characterized using infrared spectroscopy (IR). For example... Figure 12 As shown, comparing the infrared spectra of CCEG-1 before and after PEI loading, 60PEI@CCEG-1 at 1375 cm⁻¹... 1 A new peak appears at this point, attributed to the stretching vibration peak of CN. Additionally, at 2900 cm⁻¹... 1 The vibration peak at the point is enhanced, which is due to the CH stretching vibration of -CH2- on PEI.

[0158] The morphology and elemental distribution after PEI loading were characterized using SEM and EDS. For example... Figure 13 As shown, 60PEI@CCEG-1 has an octahedral morphology. The elemental composition obtained by EDS energy dispersive spectroscopy is consistent with that of CCEG-1, both containing four elements: Cl, Al, O, and C, and an additional N element, which belongs to the amino groups on PEI.

[0159] (3) Adsorption capacity of 60PEI@CCEG-1: Nitrogen adsorption isotherm at 77 K: such as Figure 14 As shown, the specific surface area of ​​CCEG-1 is S BET = 1086 m 2 g 1 The adsorption capacity for N2 at 1 bar is 800 cm⁻¹. 3 g 1 After loading with PEI, a large amount of PEI entered the pores of CCEG-1, causing the specific surface area of ​​60PEI@CCEG-1 to decrease to 78 m². 2 g 1 At 1 bar pressure, the adsorption capacity for N2 decreased to 200 cm⁻¹. 3 g 1 .

[0160] CO2 adsorption isotherm at 298 K: (e.g.) Figure 15 As shown in Figure (a), x PEI@CCEG-1 ( x The CO2 adsorption capacity of the values ​​(0, 10, 20, 50, 60, 70, 100) at 1 bar pressure was 1.01 mmol g. 1 1.52 mmol g 1 1.72 mmol g 1 1.56 mmol g 1 2.07 mmol g 1 1.39 mmol g 1 0.45 mmol g 1 .like Figure 15 As shown in Figure (b), at 0.4 mbar, x PEI@CCEG-1 ( x The CO2 adsorption capacities of (50, 60, 70, 100) were 0.31, 0.81, 0.45, and 0.30 mmol g, respectively. 1 .

[0161] x The adsorption capacity of PEI@CCEG-1 consists of two parts: chemisorption and physisorption. In the low-pressure region (0.4 mbar), chemisorption of PEI plays a dominant role, while in the high-pressure region (1 bar), physisorption of CCEG-1 plays a dominant role. Therefore, the adsorption capacity of 50PEI@CCEG-1 in the low-pressure region is superior to that of 20PEI@CCEG-1. In the high-pressure region, the loaded PEI modifies and re-divides the pores of CCEG-1 (PEI exhibits different distribution patterns within the pores as the loading increases, such as loose and open, tightly coiled, or loosely packed), thus affecting the physisorption capacity of CCEG-1. Therefore, the adsorption capacity of 50PEI@CCEG-1 in the high-pressure region is lower than that of 20PEI@CCEG-1.

[0162] Air stability of adsorption performance: such as Figure 16 and Figure 17 As shown, 60PEI@CCEG-1 can remain stable in air for at least two months, not only maintaining its crystalline state but also without losing its CO2 adsorption performance. Ten cycles of CO2 adsorption at 298 K under 0.4 mbar were conducted, and the CO2 adsorption capacity remained constant. This demonstrates that after ten adsorption cycles, the CO2 adsorption capacity of 60PEI@CCEG-1 remains essentially unchanged.

[0163] Breakthrough experiment: 60PEI@CCEG-1 was activated by evacuating to 150 °C for 12 h, followed by heating at 120 °C with 20 mL of helium for 2 h, yielding 0.2 g of activated sample. A breakthrough experiment was then conducted on the activated 60PEI@CCEG-1 under dry air (dry air flow rate into the adsorption column was 40 mL / min, CO2 concentration was 400 ppm) to simulate its performance in directly capturing CO2 from the air in practical applications. Figure 18 As shown, at a concentration ratio of 0.5, the average dynamic capture amount (CO2) over ten rounds was 12.63 mL g. -1 This indicates that 60PEI@CCEG-1 has excellent dynamic capture performance and cycle stability for CO2 in the air.

[0164] Comparison of adsorption performance of different aluminum-based MOFs: CO2 adsorption isotherms of three aluminum-based MOFs (CCEG-1, CAU-10, and MIL-68) before and after PEI loading were tested at 298 K, and the corresponding CO2 adsorption capacity was calculated. As shown in Table 4, the CO2 adsorption capacity of 60PEI@CCEG-1 at 0.4 mbar was much higher than that of the other two aluminum-based MOFs loaded with PEI.

[0165] Table 4. Comparison of adsorption performance of different aluminum-based MOFs at 298 K Analysis suggests that the excellent CO2 adsorption performance of 60PEI@CCEG-1 may be due to the following reasons: First, PEI has a large number of primary, secondary, and tertiary amine functional groups, which can achieve CO2 adsorption and desorption through reversible chemical reactions with CO2, thereby effectively improving the CO2 adsorption performance; Second, the pore size and shape of CCEG-1 are conducive to the loading effect of PEI.

[0166] For MOFs with one-dimensional channels, when the pore size is small, the channels become blocked after loading PEI, making it difficult for CO2 to enter, such as 60PEI@CAU-10. When the pore size is large, the flexible chain-like PEI tends to overlap in the channels after loading PEI, making it difficult to expose adsorption sites and weakening the interaction with CO2, such as 60PEI@MIL-68. Only when the pore size is moderate can the adsorption sites be fully exposed after loading PEI, thereby effectively enhancing the CO2 capture performance.

[0167] For MOFs with cage-like pores, such as CCEG-1 in this application, small-sized pores can prevent excessive PEI from entering the pores and overlapping, while large-sized cages can fully expose the adsorption sites, thereby effectively enhancing the CO2 capture performance.

[0168] Application Example 4 This application example demonstrates the use of CCEG-1 in water vapor enrichment.

[0169] (1) Heat treatment of CCEG-1: After synthesis, CCEG-1 underwent three rounds of methanol exchange and was dried at room temperature. Approximately 1 g of CCEG-1 powder was placed in a porcelain crucible and then placed in a muffle furnace. The crucible was heated for 12 h at 150 ℃, 200 ℃, and 250 ℃ in air, respectively, to obtain CCEG-1-150, CCEG-1-200, and CCEG-1-250. Figure 19 and Figure 20 As shown in the PXRD patterns and 77 K nitrogen adsorption-desorption curves of CCEG-1 after heat treatment at different temperatures, it can be seen that the material retains its crystalline state and the pore volume is improved after heat treatment.

[0170] Water vapor adsorption isotherm tests were performed on CCEG-1 after heat treatment at different temperatures at 298 K. See Table 5 and... Figure 21 As shown, the starting pressure (i.e., the jump point of the adsorption isotherm) is earlier after heat treatment, meaning that CCEG-1 can absorb water at lower humidity after heat treatment; the ratio of the actual pressure of water vapor to the saturated vapor pressure is... P / P When 0 ≈ 0.9, the adsorption capacity for water vapor first increases and then decreases with increasing heat treatment temperature, reaching its maximum value with CCEG-1-200. Furthermore, after 500 rounds of water vapor adsorption-desorption tests, CCEG-1-200 maintains its original octahedral morphology, uniform particle size, and water vapor adsorption capacity remaining between 650 mg / g and 730 mg / g, demonstrating excellent cycle stability.

[0171] Table 5. Comparison of adsorption performance of CCEG-1 at 298 K after heat treatment at different temperatures The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0172] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. An application of an aluminum-based metal-organic framework material in the field of adsorption, characterized in that, The chemical formula of the aluminum-based metal-organic framework material is: [Al 24 (OCH3) x (OH) 56 x (PTA)6](OAc) y Cl4 y ; in, x = 14~35, y = 0~1; PTA 2 OAc represents the terephthalate ion. This represents the acetate ion; The aluminum-based metal-organic framework material is based on Al 24 The cluster is a metallic node, each of the Al nodes 24 Cluster with 12 from PTA 2 The carboxyl groups are linked together, each PTA 2 With the two Al 24 Clusters are connected.

2. The application of the aluminum-based metal-organic framework material as described in claim 1 in the field of adsorption, characterized in that, The applications include: A mixture is provided in which the concentration of hexavalent chromium is 0.5 ppm to 400 ppm; The mixture was subjected to adsorption treatment using the aluminum-based metal-organic framework material to ensure that the concentration of hexavalent chromium was ≤0.1 ppm. The aluminum-based metal-organic framework material after adsorption treatment is washed sequentially with NaCl solution and water to regenerate it.

3. The application of the aluminum-based metal-organic framework material as described in claim 2 in the field of adsorption, characterized in that, The adsorption treatment includes the following steps: The aluminum-based metal-organic framework material is dispersed in the mixture and then allowed to stand, stirred, or sonicated. or, The aluminum-based metal-organic framework material and inorganic packing material are packed into a chromatographic column at a mass ratio of 1:(50~60), and the mixture is allowed to flow through the chromatographic column at a flow rate of 10 mL / min~50 mL / min.

4. The application of the aluminum-based metal-organic framework material as described in claim 1 in the field of adsorption, characterized in that, The applications include: The aluminum-based metal-organic framework material is used to adsorb a mixed gas containing propylene and ethylene to capture propylene in the mixed gas. The aluminum-based metal-organic framework material after adsorption treatment is desorbed using a protective gas to recover the captured propylene.

5. The application of the aluminum-based metal-organic framework material as described in claim 4 in the field of adsorption, characterized in that, One or more of the following conditions must be met: (1) Prior to the adsorption treatment, the method further includes the following step: converting the counter anion of the aluminum-based metal-organic framework material into Cl... Replaced with Br I SO4 2 and [Fe(CN)6] 3 Any one of them; (2) In the mixed gas, the mass ratio of propylene to ethylene is 1:(1~9); (3) At 298 K and 1 bar, the aluminum-based metal-organic framework material has an adsorption capacity of ≥6 mmol / g for propylene and ≤1.7 mmol / g for ethylene; (4) The protective gas includes any one of nitrogen, helium and argon; (5) The purity of the recovered propylene is ≥99.5%.

6. The application of the aluminum-based metal-organic framework material as described in claim 1 in the field of adsorption, characterized in that, The applications include: A composite material was prepared by loading polyethyleneimine onto the aluminum-based metal-organic framework material; The composite material is used to adsorb CO2 to enrich CO2.

7. The application of the aluminum-based metal-organic framework material as described in claim 6 in the field of adsorption, characterized in that, The mass ratio of the polyethyleneimine to the aluminum-based metal-organic framework material is (10~70):

100.

8. The application of the aluminum-based metal-organic framework material as described in claim 7 in the field of adsorption, characterized in that, At 298 K and 1 bar, the composite material adsorbs CO2 at a rate ≥1.3 mmol / g. At 298 K and 0.4 mbar, the composite material adsorbs CO2 at a rate ≥0.3 mmol / g.

9. The application of the aluminum-based metal-organic framework material as described in claim 1 in the field of adsorption, characterized in that, The applications include: The aluminum-based metal-organic framework material was heat-treated in air at 150 ℃~250 ℃. The heat-treated aluminum-based metal-organic framework material is used to adsorb water vapor to enrich it.

10. The application of the aluminum-based metal-organic framework material as described in claim 9 in the field of adsorption, characterized in that, In 298 K, P / P At 0≈0.9, the aluminum-based metal-organic framework material maintains an adsorption capacity of ≥650 mg / g for water vapor; in, P / P 0 represents the ratio of the actual pressure of water vapor to the saturated vapor pressure.

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