Preparation method of amino-functionalized metal organic framework material and application thereof

Abstract

The application relates to a preparation method of an amino-functionalized metal organic framework material and application of the prepared material to CO2 / N2 and CO2 / CH4 separation. The preparation method is as follows: adenine and copper nitrate trihydrate are dissolved in N, N'-dimethylacetamide to obtain a first mixed solution; a carboxylic acid and potassium carbonate are dissolved in deionized water to obtain a second mixed solution; the second mixed solution is added to the first mixed solution, and stirring reaction is carried out; and the obtained solid product is vacuum dried to obtain the amino-functionalized metal organic framework material. The amino-functionalized metal organic framework material prepared by the application has high CO2 adsorption selectivity and adsorption capacity, and has good acid resistance, alkali resistance and water resistance stability. The amino-functionalized metal organic framework material prepared by the application has excellent separation effect when applied to industrial CO2 adsorption separation.

Description

Technical Field

[0001] This invention relates to the field of gas adsorption and separation technology, and more specifically, to a method for preparing an amino-functionalized metal-organic framework material and its application. Background Technology

[0002] With social development and industrial technological upgrading, human energy demand is increasing daily. However, fossil fuels remain the primary energy source globally, and sustainable new energy technologies still require substantial economic investment. The combustion of fossil fuels generates large amounts of carbon emissions, causing a continuous rise in atmospheric CO2 concentration, exacerbating the greenhouse effect, and triggering a series of climate problems.

[0003] Metal-organic frameworks (MOFs) are a class of crystalline porous materials with periodic network structures, formed by the self-assembly of inorganic metal ions or metal clusters with organic ligands through coordination bonds. Compared with traditional porous materials, including silica gel, porous carbon, and zeolite molecular sieves, MOFs have advantages such as ultra-high specific surface area, rich structures, and modifiable pore structures, making them effective in the adsorption, capture, and separation of CO2 gas. For example, Cu-BTC (also known as HKUST-1) is one of the metal-organic framework materials with excellent CO2 adsorption performance under normal temperature and pressure conditions. The adsorption capacity of this material for CO2 at 10℃ and 100kPa can reach 7.0 mmol / g (P.Aprea,D.Caputo,N.Gargiulo,etal.Modeling carbon dioxide adsorption on microporous substrates comparison between Cu-BTC metal-organic framework and 13X zeolitic molecular sieve[J],J Chem Eng Data,55(2010)3655-3661). However, in practical applications, water vapor is ubiquitous, and many metal-organic framework materials, including Cu-BTC, have very poor water vapor stability. When exposed to humid environments, their metal-ligand coordination bonds are easily broken, leading to framework collapse (NCBurtch, H. Jasuja, KSWalton, Waterstability and adsorption in metal-organic frameworks[J], Chem Rev, 114(2014)10575-10612). Therefore, it is urgent to prepare metal-organic framework materials with good stability to meet the requirements for the stability of adsorption materials in practical applications.

[0004] CN116925378A discloses a method for preparing CuIn metal-organic framework materials and their application in CO2 adsorption. This method uses 4'-(1H-tetrazol-5-yl)-[1,1'-biphenyl]-3,5-dicarboxylic acid as the organic ligand, and the material's CO2 adsorption capacity is 3.0 mmol / g. This patent uses a solvothermal reaction to prepare the adsorbent material, which places high demands on equipment safety and leaves room for optimization in terms of process energy consumption. Furthermore, the organic ligand used in this patent has a complex structure, resulting in high raw material costs.

[0005] CN117046450A discloses a method for preparing a carbide slag-based metal-organic framework material and its application in CO2 adsorption. This patent uses carbide slag with a CaO mass fraction of over 90% to react with the organic ligand squaric acid through ball milling. After washing, a solid powder is obtained, which is then modified with tetraethylenepentamine to prepare the adsorbent material. The material's CO2 adsorption capacity reaches 2.89 mmol / g. This patent requires multiple reaction steps to obtain the adsorbent material, making the operation process complex. Furthermore, the corrosive organic amines used in the process leave residues in the waste liquid, which is harmful to the environment.

[0006] For the reasons mentioned above, it is essential to develop an adsorbent material and preparation method that has good chemical stability, high CO2 selectivity and adsorption capacity. Summary of the Invention

[0007] This invention addresses the requirements for CO2 gas adsorption, capture, and separation. Its primary objective is to provide a method for preparing amino-functionalized metal-organic framework materials and their application in adsorbing low concentrations of CO2 in gases. The amino-functionalized metal-organic framework materials provided by this invention exhibit good selectivity and adsorption capacity for CO2.

[0008] This invention is achieved through the following technical solution:

[0009] A method for preparing an amino-functionalized metal-organic framework material includes the following preparation steps:

[0010] (1) Dissolve adenine and copper nitrate trihydrate in N,N'-dimethylacetamide and stir for 10 min to obtain the first mixed solution; dissolve carboxylic acid and potassium carbonate in deionized water and stir for 10 min to obtain the second mixed solution;

[0011] (2) The second mixed solution obtained in step (1) is added dropwise to the first mixed solution, and the reaction is stirred for 36h to 48h to obtain the reaction product. The reaction solution is filtered, and the solid product is soaked in ethanol and filtered in sequence to obtain green solid powder.

[0012] (3) The solid powder obtained in step (2) is vacuum dried to obtain amino-functionalized metal-organic framework material.

[0013] Preferably, in step (1), the molar ratio of adenine to copper nitrate trihydrate is 1:(0.5-5).

[0014] Preferably, in step (1), the carboxylic acid refers to one of succinic acid, glutaric acid, formic acid, acetic acid, and propionic acid.

[0015] Preferably, in step (1), the volume ratio of deionized water to N,N'-dimethylacetamide is 1:(0.6-5).

[0016] Preferably, in step (1), the molar ratio of adenine:carboxylic acid:potassium carbonate is 1:(0.5-5):(0.2-2).

[0017] Preferably, in step (3), the vacuum drying refers to vacuum drying at 60℃~100℃ for 2h~6h.

[0018] An amino-functionalized metal-organic framework material is used in the separation of mixed gases containing CO2 and N2 or CO2 and CH4.

[0019] The above-mentioned amino-functionalized metal-organic framework materials, as CO2 selective adsorbents, were applied to adsorb industrial CO2 at room temperature and atmospheric pressure, with a CO2 adsorption capacity of 2.83–4.72 mmol / g, and exhibited good acid, alkali and water resistance.

[0020] The preparation method and the product obtained by the present invention have the following advantages and beneficial effects:

[0021] (1) The preparation method of the present invention is simple to operate, easy to implement, and has good repeatability;

[0022] (2) Compared with the traditional solvothermal synthesis method (above 100°C), the present invention synthesizes materials at room temperature, which is more energy-efficient and safer;

[0023] (3) Compared with existing amino-functionalized metal-organic framework materials, the amino-functionalized metal-organic framework materials prepared by this invention have low cost, with the total price of organic ligands being about RMB 600 / kg, and at the same time have good acid resistance, alkali resistance and water resistance stability.

[0024] (4) The adsorbent material used in this invention has high CO2 adsorption selectivity and adsorption capacity. Attached Figure Description

[0025] Figure 1 The CO2 adsorption isotherms of the amino-functionalized metal-organic framework materials obtained in Examples 1-5 of this invention are shown.

[0026] Figure 2The adsorption isotherms of Cu-AD-SA obtained in Example 1 of this invention for CO2, CH4 and N2 at room temperature;

[0027] Figure 3 The adsorption isotherms of Cu-AD-FA obtained in Example 3 of this invention for CO2, CH4 and N2 at room temperature;

[0028] Figure 4 The adsorption selectivity curves of Cu-AD-SA for CO2 / CH4 and CO2 / N2 obtained in Example 1 of this invention are shown.

[0029] Figure 5 The CO2 / CH4 and CO2 / N2 adsorption selectivity curves of Cu-AD-FA obtained in Example 3 of this invention are shown.

[0030] Figure 6 The PXRD spectra of the amino-functionalized metal-organic framework materials obtained in Examples 1-5 of this invention after acid immersion.

[0031] Figure 7 The PXRD spectra of the amino-functionalized metal-organic framework materials obtained in Examples 1-5 of this invention after alkali immersion.

[0032] Figure 8 The PXRD spectra of the amino-functionalized metal-organic framework materials obtained in Examples 1-5 of this invention after immersion in deionized water are shown. Detailed Implementation

[0033] The following describes preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

[0034] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0035] Example 1

[0036] A method for preparing an amino-functionalized metal-organic framework material, wherein the preparation of the adsorbent material includes the following steps:

[0037] (1) Dissolve 0.8 g adenine (5.92 mmol, n1) and 1.6 g copper nitrate trihydrate (6.62 mmol, n2) in 30 mL N,N'-dimethylacetamide and stir for 10 min to obtain the first mixed solution; dissolve 0.7 g succinic acid (5.93 mmol, n3) and 0.4 g potassium carbonate (2.89 mmol, n4) in 15 mL deionized water and stir for 10 min to obtain the second mixed solution;

[0038] (2) Add the second mixed solution obtained in step (1) to the first mixed solution, stir the reaction for 36 hours to obtain the reaction product, filter the reaction solution, and soak the solid product in ethanol and filter it in sequence to obtain green solid powder.

[0039] (3) The solid powder obtained in step (2) is placed at 60°C and vacuum dried for 4 hours to obtain an amino-functionalized metal-organic framework material, denoted as Cu-AD-SA material. Then, it is sealed and stored or the adsorption and removal performance of the material is tested.

[0040] Example 2

[0041] A method for preparing an amino-functionalized metal-organic framework material, wherein the preparation of the adsorbent material includes the following steps:

[0042] (1) Dissolve 0.8 g adenine (5.92 mmol, n1) and 1.6 g copper nitrate trihydrate (6.62 mmol, n2) in 30 mL N,N'-dimethylacetamide and stir for 10 min to obtain the first mixed solution; dissolve 0.8 g glutaric acid (6.05 mmol, n3) and 0.4 g potassium carbonate (2.89 mmol, n4) in 15 mL deionized water and stir for 10 min to obtain the second mixed solution;

[0043] (2) Add the second mixed solution obtained in step (1) to the first mixed solution, stir the reaction for 40 h to obtain the reaction product, filter the reaction solution, and soak the solid product in ethanol and filter it in sequence to obtain green solid powder.

[0044] (3) The solid powder obtained in step (2) is placed at 80°C and vacuum dried for 6 hours to obtain an amino-functionalized metal-organic framework material, denoted as Cu-AD-GA material. Then, it is sealed and stored or the adsorption and removal performance of the material is tested.

[0045] Example 3

[0046] A method for preparing an amino-functionalized metal-organic framework material, wherein the preparation of the adsorbent material includes the following steps:

[0047] (1) Dissolve 0.8 g adenine (5.92 mmol, n1) and 1.6 g copper nitrate trihydrate (6.62 mmol, n2) in 30 mL N,N'-dimethylacetamide and stir for 10 min to obtain the first mixed solution; dissolve 0.6 g formic acid (6.52 mmol, n3) and 0.4 g potassium carbonate (2.89 mmol, n4) in 15 mL deionized water and stir for 10 min to obtain the second mixed solution;

[0048] (2) Add the second mixed solution obtained in step (1) to the first mixed solution, stir the reaction for 48 hours to obtain the reaction product, filter the reaction solution, and soak the solid product in ethanol and filter it in sequence to obtain green solid powder.

[0049] (3) The solid powder obtained in step (2) is placed at 100°C and vacuum dried for 2 hours to obtain an amino-functionalized metal-organic framework material, denoted as Cu-AD-FA material. Then, it is sealed and stored or the adsorption and removal performance of the material is tested.

[0050] Example 4

[0051] A method for preparing an amino-functionalized metal-organic framework material, wherein the preparation of the adsorbent material includes the following steps:

[0052] (1) Dissolve 0.8 g adenine (5.92 mmol, n1) and 1.6 g copper nitrate trihydrate (6.62 mmol, n2) in 30 mL N,N'-dimethylacetamide and stir for 10 min to obtain the first mixed solution; dissolve 0.8 g acetic acid (6.67 mmol, n3) and 0.4 g potassium carbonate (2.89 mmol, n4) in 15 mL deionized water and stir for 10 min to obtain the second mixed solution;

[0053] (2) Add the second mixed solution obtained in step (1) to the first mixed solution, stir the reaction for 42 hours to obtain the reaction product, filter the reaction solution, and soak the solid product in ethanol and filter it in sequence to obtain green solid powder.

[0054] (3) The solid powder obtained in step (2) is placed at 60°C and vacuum dried for 6 hours to obtain an amino-functionalized metal-organic framework material, denoted as Cu-AD-AC material. Then, it is sealed and stored or the adsorption and removal performance of the material is tested.

[0055] Example 5

[0056] A method for preparing an amino-functionalized metal-organic framework material, wherein the preparation of the adsorbent material includes the following steps:

[0057] (1) Dissolve 0.8 g adenine (5.92 mmol, n1) and 1.6 g copper nitrate trihydrate (6.62 mmol, n2) in 30 mL N,N'-dimethylacetamide and stir for 10 min to obtain the first mixed solution; dissolve 0.9 g propionic acid (6.07 mmol, n3) and 0.4 g potassium carbonate (2.89 mmol, n4) in 15 mL deionized water and stir for 10 min to obtain the second mixed solution;

[0058] (2) Add the second mixed solution obtained in step (1) to the first mixed solution, stir the reaction for 48 hours to obtain the reaction product, filter the reaction solution, and soak the solid product in ethanol and filter it in sequence to obtain green solid powder.

[0059] (3) The solid powder obtained in step (2) is placed at 60°C and vacuum dried for 4 hours to obtain an amino-functionalized metal-organic framework material, denoted as Cu-AD-PA material. Then, it is sealed and stored or the adsorption and removal performance of the material is tested.

[0060] Test example:

[0061] a. Pore structure and specific surface area of ​​amino-functionalized metal-organic framework materials:

[0062] The pore structures of Cu-AD-SA, Cu-AD-GA, Cu-AD-FA, Cu-AD-AC, and Cu-AD-PA prepared in Examples 1-5 of this invention were tested using an ASAP 2020 pore size analyzer manufactured by Micromeritics, Inc., USA. The results are shown in Table 1.

[0063] Table 1:

[0064]

[0065] As shown in Table 1, the BET specific surface area of ​​the amino-functionalized metal-organic framework materials prepared in this invention ranges from 732.3 to 1008.2 m². 2 / g, total pore volume is 0.27-0.35cm³ 3 The pore size is in the range of 0.42-0.48 nm, indicating that the amino-functionalized metal-organic framework materials prepared in Examples 1-5 of this invention have a microporous structure with high specific surface area and large pore volume. Furthermore, the amino groups on the adenine ligands in the amino-functionalized metal-organic framework materials prepared in this invention all point inwards into the pores, and the pore size is relatively small, slightly larger than the kinetic diameter of a CO2 molecule (0.33 nm). This will help improve the adsorption force of the amino-functionalized metal-organic framework materials on CO2 molecules.

[0066] b. Adsorption isotherms of CO2, CH4, and N2 in amino-functionalized metal-organic framework materials:

[0067] This invention uses a 3-Flex all-purpose adsorption analyzer manufactured by Micromeritics, USA, to perform gas adsorption isotherm tests on the materials prepared in Examples 1-5 of this invention for CO2, CH4, and N2. Before testing, the samples were subjected to vacuum degassing treatment at 80°C for 6 hours.

[0068] Figure 1 This is the adsorption isotherm of CO2 on the amino-functionalized metal-organic framework materials prepared in Examples 1-5 of this invention at 25°C. Figure 1 Analysis revealed that, under normal temperature and pressure, the CO2 adsorption capacity of the amino-functionalized metal-organic framework materials, in descending order, was Cu-AD-SA > Cu-AD-FA > Cu-AD-GA > Cu-AD-AC > Cu-AD-PA, with CO2 adsorption capacities of 4.72, 4.59, 3.93, 3.82, and 2.83 mmol / g, respectively. Notably, the amino-functionalized metal-organic framework materials prepared in Examples 1-5 of this invention all exhibited preferential CO2 adsorption and high CO2 adsorption capacities, with Cu-AD-SA showing the highest CO2 adsorption capacity. Adsorption isotherm tests of CH4 and N2 gases were conducted on Cu-AD-SA and Cu-AD-FA, which showed the highest CO2 adsorption capacities. The results indicated that Cu-AD-SA's CO2 adsorption capacity was 5.9 and 18.2 times that of its CH4 and N2 adsorption capacities, respectively, while Cu-AD-FA's CO2 adsorption capacity was 5.6 and 17.8 times that of its CH4 and N2 adsorption capacities, respectively.

[0069] c. Adsorption selectivity of amino-functionalized metal-organic framework materials Cu-AD-SA and Cu-AD-FA for CO2 and CH4, and CO2 and N2:

[0070] For Cu-AD-SA and Cu-AD-FA, which have the highest CO2 adsorption capacity, based on their adsorption isotherm data for CO2, CH4, and N2 at 25℃, such as Figure 2 and Figure 3 As shown, the adsorption selectivity of CO2 / CH4 and CO2 / N2 was calculated using an ideal adsorption solution model. Figure 4 The adsorption selectivity curves of Cu-AD-SA prepared in Example 1 of this invention for CO2 / CH4 and CO2 / N2 are shown. Figure 4 The results indicate that the adsorption selectivity of Cu-AD-SA for CO2 / CH4 and CO2 / N2 first decreases and then increases with increasing pressure. Figure 5 The adsorption selectivity curves of Cu-AD-FA prepared in Example 3 of this invention for CO2 / CH4 and CO2 / N2 are shown. Figure 5The results show that the adsorption selectivity of Cu-AD-FA for CO2 / CH4 and CO2 / N2 first decreases and then increases with increasing pressure. Notably, at 100 kPa, the adsorption selectivity of Cu-AD-SA for CO2 / CH4 and CO2 / N2 is 18.5 and 61.6, respectively, while that of Cu-AD-FA is 34.3 and 82.2, respectively, both higher than that of Cu-AD-SA. This is because Cu-AD-FA has a slightly higher CO2 adsorption capacity at low pressure than Cu-AD-SA. The high adsorption selectivity of the amino-functionalized metal-organic framework material prepared in this invention for CO2 / CH4 and CO2 / N2 is due to the presence of amino groups pointing towards the pores within the framework. The H atoms on the amino groups can generate strong electrostatic interactions with the O atoms in the CO2 molecule, while only generating weaker interactions with CH4 and N2 molecules. Therefore, the amino groups pointing towards the pores in the amino-functionalized metal-organic framework material prepared by this invention can enhance the difference in molecular adsorption forces of the framework for CO2 / CH4 and CO2 / N2, thereby improving the adsorption selectivity of CO2 / CH4 and CO2 / N2.

[0071] d. Acid, alkali and water resistance stability of amino-functionalized metal-organic framework materials:

[0072] This invention employs a Bruker D8-ADVANCE fully automated X-ray diffractometer (Germany) to characterize the crystal structures of Cu-AD-SA, Cu-AD-GA, Cu-AD-FA, Cu-AD-AC, and Cu-AD-PA prepared in Examples 1-5 of this invention after stability testing. The five samples prepared in Examples 1-5 were immersed in hydrochloric acid (pH=2), sodium hydroxide solution (pH=12), and deionized water for one week. Afterward, the samples were removed and scanned within a range of 5-50° at twice the diffraction angle, with a scan step of 0.02°. The voltage and current used for the test were 40 kV and 40 mA, respectively. Cu K0 was used as the diffraction method. α ray.

[0073] Figure 6-8 The images show the PXRD spectra of Cu-AD-SA, Cu-AD-GA, Cu-AD-FA, Cu-AD-AC, and Cu-AD-PA prepared in Examples 1-5 of this invention after immersion in acid, alkali, and deionized water, respectively. Figure 6-8As can be seen, the amino-functionalized metal-organic framework materials prepared in Examples 1-5 of this invention have similar PXRD diffraction patterns. All materials exhibit three characteristic diffraction peaks at twice the diffraction angles of 6.8, 13.2, and 13.7 degrees. These characteristic diffraction peaks are basically consistent with the characteristic diffraction peaks of the corresponding materials reported in the literature (L. Wang, K. Wang, H. An, et al. A hydrolytically stable Cu(II)-based metal-organic framework with easily accessible ligands for water harvesting[J], ACS Appl. Mater. Interfaces, 13(2021) 49509-49518; L. Wang, J. Lv, Q. Ye, et al. Nanoporous Cu(II)-adenine-based metal–organic frameworks for selective adsorption of C2H2 from C2H4 and CO2[J], ACS The results (Appl. Mater. Interfaces, 6(2023) 22095-22103) demonstrate the successful preparation of the target amino-functionalized metal-organic framework material, and also indicate that the amino-functionalized metal-organic framework materials prepared under the experimental conditions of Examples 1-5 have similar crystal structures. Furthermore, the PXRD spectra of all five samples exhibit narrow diffraction peaks and strong peak intensities, indicating that all five samples have high crystallinity. Notably, after treatment with acid, alkali, and deionized water, the PXRD spectra of the five samples remained unchanged, indicating that the treated samples maintained the integrity of their frameworks, proving that the amino-functionalized metal-organic framework material prepared in this invention has good acid, alkali, and water resistance.

[0074] 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.

[0075] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing an amino-functionalized metal-organic framework material, characterized in that, Includes the following steps: (1) Adenine and copper nitrate trihydrate are dissolved in N,N'-dimethylacetamide and stirred to obtain a first mixed solution; succinic acid and potassium carbonate are dissolved in deionized water and stirred to obtain a second mixed solution; the molar ratio of adenine and copper nitrate trihydrate is 1:1.12; the molar ratio of adenine:succinic acid:potassium carbonate is 1:1.00:0.49; the volume ratio of deionized water to N,N'-dimethylacetamide is 1:2; (2) The second mixed solution obtained in step (1) is added dropwise to the first mixed solution, and the reaction is stirred for 36 hours to obtain the reaction product. The reaction solution is filtered, and the solid product is soaked in ethanol and filtered in sequence to obtain green solid powder. (3) The solid powder obtained in step (2) is vacuum dried at 60°C for 4 hours to obtain the amino-functionalized metal-organic framework material.

2. The preparation method according to claim 1, characterized in that, In step (2), the soaking time is 2h to 24h.

3. An amino-functionalized metal-organic framework material prepared by the method according to any one of claims 1-2, characterized in that: The material adsorbs CO2 at room temperature and atmospheric pressure, with an adsorption capacity of 4.72 mmol / g. Furthermore, the material retains its framework integrity after being immersed for one week in hydrochloric acid solution (pH=2), sodium hydroxide solution (pH=12), and deionized water.

4. The amino-functionalized metal-organic framework material of claim 3 is used for the separation of mixed gases containing CO2 and N2.

5. The amino-functionalized metal-organic framework material of claim 3 is used for the separation of mixed gases containing CO2 and CH4.

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