Preparation method of a class of electron-rich metal-organic framework SO2 adsorbents

Abstract

This invention relates to a method for preparing a class of electron-rich metal-organic framework (MOF) SO2 adsorbents. The material is a two-dimensional MOF formed by effectively coordinating electron-rich nitrogen-containing tridentate carboxylic acids (H3BTB-NH2 or H3TPY) with metal clusters. These electron-rich groups possess strong electron-donating capabilities, enabling electron-donating interactions with SO2 molecules, thereby enhancing SO2 adsorption capacity and ensuring favorable desorption conditions. The different positions of the nitrogen-containing groups within the MOF structure significantly affect the SO2 adsorption performance of the material. The MOF material designed in this invention introduces different types of nitrogen-containing groups into its tridentate carboxylic acid organic ligands to adjust the spatial sites and electronic properties of the nitrogen groups, further optimizing the SO2 adsorption capacity. This not only achieves highly efficient SO2 adsorption and desorption but also lays the foundation for the subsequent development of environmental remediation materials.

Description

Technical Field

[0001] This invention relates to the fields of materials science and environmental engineering, particularly the design, preparation, and application of metal-organic frameworks (MOFs). Specifically, this invention focuses on the application of two-dimensional, stable MOF materials formed by the coordination of tridentate carboxylic acid ligands containing electron-rich nitrogen groups with metal clusters in SO2 gas adsorption. By optimizing the position and electronic properties of the nitrogen-containing groups in the tridentate carboxylic acid organic ligands, the formed two-dimensional zirconium-based MOF materials are endowed with certain electron-rich properties. Through suitable interactions between the electron-rich groups and SO2 gas, the adsorption performance of the prepared MOF materials for SO2 is improved, and easier desorption conditions are ensured. Furthermore, a simple "one-pot" preparation method for related electron-rich MOF materials is achieved, thus providing a novel and efficient material solution for environmental remediation and gas adsorption technology. This technology has significant application prospects in industrial waste gas treatment, environmental pollution control, and sustainable development. Background Technology

[0002] Sulfur dioxide (SO2) is a corrosive and irritating gas widely present in industrial production and fuel combustion processes. Its emissions not only severely impact air quality but also pose a threat to human health. Long-term exposure to SO2 can lead to respiratory diseases, skin allergies, and other health problems. Furthermore, the acid rain formed by the reaction of SO2 with moisture causes soil acidification, water pollution, and ecosystem damage, resulting in a series of environmental issues. Therefore, the effective removal of SO2 gas, especially in industrial waste gas treatment, is of paramount importance.

[0003] Currently, gas adsorption technology is one of the main methods for SO2 removal. Among numerous adsorption materials, metal-organic frameworks (MOFs) have attracted much attention due to their unique structure and excellent performance. MOFs are self-assembled from metal ions and organic ligands, possessing high specific surface area, tunable pore structure, host-guest interactions, and good chemical and thermal stability. This makes MOFs exhibit great application potential in gas separation and adsorption. Studies have shown that compared with traditional adsorbents such as metal oxides (e.g., MnOx, CuO, ZnO), activated carbon, and zeolites, MOFs with specific topologies, functional groups, and pore sizes exhibit superior SO2 capture capabilities and can efficiently remove SO2 at lower concentrations, providing a good foundation for their application in environmental remediation. By utilizing urea-functionalized bidentate carboxylic acid ligands to coordinate with divalent zinc ions, and further coordinating 4,4′-bipyridine with the aforementioned paddlewheel-structured divalent zinc ions, a three-dimensional extended MOF network structure can be formed, significantly improving the capture capacity of SO2 and NH3 (ACS Appl. Mater. Interfaces 2017, 9, 37419−37434). The high adsorption capacity is attributed to the strong hydrogen bonding interaction between the urea group and SO2 and NH3. However, the stability of the formed MOF is problematic (ACS Appl. Mater. Interfaces 2017, 9, 37419−37434), and the synthesis process is relatively complex. Furthermore, while inorganic high-nitrogen carbon-based zirconium phosphate broad-spectrum adsorbents (CN113101891 A) can be obtained by using melamine-zirconium complexes and chitosan-formaldehyde polymers through processes such as dipping in metal salt solutions followed by high-temperature sintering, these adsorbents lack selective adsorption characteristics for SO2 and require high temperatures for desorption. Therefore, designing adsorbent materials with high SO2 adsorption capacity and easy desorption through reasonable structural design (topology, functional groups, etc.) is crucial for achieving efficient SO2 capture and treatment.

[0004] This invention reveals that introducing nitrogen-containing, electron-rich groups into the framework structure constructed from tripenterate carboxylic acid ligands and zirconium ions can enhance the adsorption performance of zirconium-based MOF materials. These electron-rich groups not only effectively interact with SO2 molecules through electron-donating interactions but also improve the material's selectivity. For example, nitrogen-containing groups, due to their excellent electron-donating properties, can form strong interactions with sulfur atoms in SO2, thereby increasing adsorption capacity. Furthermore, unlike zeolite or molecular sieve adsorbents, the relatively moderate host-guest interaction between SO2 and the framework material ensures relatively easy desorption of SO2, thus avoiding the need for high-temperature heating. Simultaneously, the designed and synthesized two-dimensional electron-rich zirconium-based MOF material can be easily and rapidly prepared using a one-pot method, laying the foundation for subsequent mass production and applications in related fields. This invention aims to develop a two-dimensional, highly stable zirconium-based MOF material containing electron-rich groups. It utilizes two types of tridentate carboxylic acid ligands (H3BTB-NH2 and H3TPY) with electron-rich nitrogen-containing groups to effectively coordinate with metal clusters, resulting in a two-dimensional MOF material with excellent solubility, processability, and resistance to strong acids and bases, thereby improving its SO2 adsorption performance. By controlling the position of the nitrogen groups, the study investigates their performance in the SO2 adsorption process, aiming to achieve efficient SO2 adsorption and easy desorption. This research not only provides a new approach for efficient SO2 capture but also lays the foundation for the further development and application of metal-organic framework materials. By optimizing the structure and performance of the MOF, this invention expects to provide a more efficient, economical, and sustainable solution for industrial gas treatment and environmental protection. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a class of electron-rich metal-organic framework SO2 adsorbents. By using a simple solvothermal synthesis strategy and rationally designing the ratio of reactants and reaction time, the rapid formation of materials is promoted. The two-dimensional nanosheets generated by this method not only have a large specific surface area, but also have good structural stability, which helps to improve the adsorption capacity of SO2.

[0006] To achieve the above objectives, the technical solution adopted in this invention is as follows: Electron-rich nitrogen-based metal-organic frameworks are designed and synthesized to enhance SO2 adsorption performance. A simple hot solvent synthesis strategy can effectively promote the rapid formation of nanosheets. The two-dimensional nanosheets generated by this method not only possess a large specific surface area but also exhibit good structural stability, thereby significantly improving the SO2 adsorption capacity. Simultaneously, the selected organic ligands contain electron-rich groups, and the strong interaction between these electron-rich groups and SO2 endows the prepared material with excellent SO2 adsorption capacity.

[0007] To achieve the above objectives, according to another aspect of the present invention, a scheme is provided for designing and synthesizing electron-rich nitrogen-group organic ligands to coordinate with zirconium ions to form a metal-organic framework to enhance SO2 adsorption performance, comprising the following steps:

[0008] S1. ZrCl4 (0.128-0.132 mmol) and H3BTB-NH2 (30.9-40.2 mg) were added to DMF to obtain a mixed solution. Ultrapure water (4.0-4.2 ml) and formic acid (4.0-4.2 ml) were added to the mixed solution. The mixture was sonicated (15-20 minutes). After sonication, the mixture was placed in a reaction vessel and heated (120 °C). After reacting for 24 h, the resulting light brown suspension was centrifuged and washed multiple times to finally obtain a uniformly dispersed Zr-BTB-NH2 nanosheet suspension resistant to strong acids and alkalis.

[0009] S2. ZrCl4 (0.128-0.132 mmol) and H3TPY (28.2-28.4 mg) were added to DMF to obtain a mixed solution. Ultrapure water (4.0-4.2 ml) and formic acid (4.0-4.2 ml) were added to the mixed solution. The mixture was sonicated (15-20 minutes). After sonication, the mixture was placed in a reaction vessel and heated (120 °C). After reacting for 24 h, the resulting light purple suspension was centrifuged and washed multiple times to finally obtain a uniformly dispersed Zr-TPY nanosheet suspension resistant to strong acids and bases.

[0010] As a further optimization of the preparation method of the electron-rich metal-organic framework SO2 adsorbent of the present invention: H3BTB-NH2: [1,1':3',1''-Terphenyl]-4,4''-dicarboxylicacid, 3,3''-diamino-5'-(3-amino-4-carboxyphenyl), CAS: 1660960-30-4. H3TPY: 4'-(4-carboxyphenyl)-[2,2':6',2''-terpyridine]-5,5''-dicarboxylic acid, CAS No.: 1887067-79-9.

[0011] The structure of H3BTB-NH2 is as follows:

[0012] ;

[0013] The structure of H3TPY is as follows:

[0014] .

[0015] As a further optimization of the preparation method of the electron-rich metal-organic framework SO2 adsorbent of the present invention: the molar ratio of ZrCl4 and H3BTB-NH2 added in step S1 is 1.9:1-2.0:1, and the molar ratio of ZrCl4 and H3TPY added in step S2 is 1.9:1-2.0:1.

[0016] As a further optimization of the preparation method of the electron-rich metal-organic framework SO2 adsorbent of the present invention: the amount of DMF solvent added is 30.0-30.2 ml.

[0017] As a further optimization of the preparation method of the electron-rich metal-organic framework SO2 adsorbent of the present invention: the amount of ultrapure water added is 4.0-4.2 ml.

[0018] As a further optimization of the preparation method of the electron-rich metal-organic framework SO2 adsorbent of the present invention: the amount of formic acid added is 4.0-4.2 ml.

[0019] As a further optimization of the preparation method of the electron-rich metal-organic framework SO2 adsorbent of the present invention: the ultrasonic power is 200-300 W, and the cumulative ultrasonic time is 15-20 min.

[0020] As a further optimization of the preparation method of the electron-rich metal-organic framework SO2 adsorbent of the present invention: the oven heating temperature is 120 °C and the heating time is 24 h.

[0021] As a further optimization of the preparation method of the electron-rich metal-organic framework SO2 adsorbent of the present invention: the centrifugation speed in step S2 is 8000-10000 r·min. -1 Centrifuge for 5-6 minutes, and perform centrifugation and washing at least 5 times.

[0022] Application: The Zr-BTB-NH2 or Zr-TPY nanosheet suspension is dried and used as an SO2 adsorbent for SO2 gas adsorption. The mass of Zr-BTB-NH2 and Zr-TPY powder used for testing after drying is not less than 100 mg.

[0023] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0024] 1. This invention uses a hot solvent method to synthesize two-dimensional MOF nanosheets. The process is simple and easy to control, and the required operating conditions are mild. This makes the preparation of materials more efficient and faster, enabling large-scale application in industrial production and reducing production costs.

[0025] 2. The synthesized two-dimensional Zr-BTB-NH2 and Zr-TPY nanosheets possess high specific surface areas, providing more active sites and greatly enhancing their gas adsorption capacity, especially in SO2 adsorption, demonstrating excellent performance in efficiently removing harmful gases from the air and improving environmental quality. Furthermore, the two-dimensional MOF nanosheets synthesized via a one-pot method can withstand etching by strong acids and bases, and their topological structure remains essentially unchanged after treatment with strong acids or bases.

[0026] 3. The design of electron-rich groups enables strong interactions between the organic ligands and SO2, significantly improving the material's selectivity and adsorption efficiency for SO2. Zr-TPY achieves a maximum SO2 adsorption capacity of 66.3 cm⁻¹ at 1 bar pressure. 3 ·g -1 Furthermore, over 95% desorption can be achieved at room temperature. Attached Figure Description

[0027] Figure 1 The XRD (ab) and infrared (cd) spectra of Zr-BTB-NH2 and Zr-TPY nanosheets prepared in Examples 1 and 2 are shown.

[0028] Figure 2 The XRD patterns of the Zr-BTB-NH2 nanosheets prepared in Example 1 before and after treatment with strong acid and strong alkali for 12 hours are shown.

[0029] Figure 3 These are scanning electron microscope (SEM) images of the Zr-BTB-NH2 and Zr-TPY nanosheets prepared in Examples 1 and 2.

[0030] Figure 4 The N2 isotherm adsorption curves of Zr-BTB-NH2 and Zr-TPY nanosheets prepared in Examples 1 and 2 are shown.

[0031] Figure 5 The adsorption of SO2 by Zr-BTB-NH2 and Zr-TPY nanosheets prepared in Examples 1 and 2 under different pressures is shown. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. The invention will be further described in detail below with reference to specific embodiments.

[0033] <Example 1>

[0034] The following description uses Zr-BTB-NH2, which has SO2 adsorption properties, as an example. Its preparation method includes the following steps:

[0035] (1) Preparation of the mixture:

[0036] Add 0.128 mmol ZrCl4 and 30.9 mg H3BTB-NH2 to 30 ml DMF, then add 4.0 ml ultrapure water and 4.0 ml formic acid to the mixed solution to obtain the final mixed solution.

[0037] (2) Preparation of Zr-BTB-NH2 nanosheets

[0038] The mixture obtained in step (1) was subjected to ultrasonication in a water bath for 15 minutes. After ultrasonication, the mixture was placed in a reaction vessel and heated for 24 hours at an oven temperature of 120 °C. After the reaction, the resulting light brown suspension was centrifuged and washed at a speed of 8000 r·min. -1 The centrifugation time was approximately 5 minutes, with 5 centrifugation and washing operations performed simultaneously. The washed light brown suspension was then dried under vacuum at 150 °C to obtain Zr-BTB-NH2.

[0039] (3) Pretreatment of Zr-BTB-NH2 materials

[0040] Zr-BTB-NH2 powder was placed in a vacuum drying oven and dried at 100 °C for 12 hours to remove moisture and volatile substances. The dried sample was then cooled to room temperature under an inert gas atmosphere.

[0041] (4) SO2 adsorption test

[0042] The test system is purged with inert gas (N2) for 15-30 minutes to ensure the absence of impurities. The pretreated Zr-BTB-NH2 powder is then evenly distributed in the sample chamber of the adsorption test equipment, ensuring good dispersion. A known concentration of SO2 gas (1000 ppm) is slowly introduced into the test equipment, ensuring a stable gas flow rate. The test temperature is set to 28 °C and maintained constant; temperature data is recorded.

[0043] Example 1 illustrates a method for preparing SO2 adsorbent materials based on Zr-BTB-NH2. However, the above method is not limited to the development of SO2 adsorbent materials; in fact, this gas adsorbent material can be extended to other types of target gases.

[0044] <Example 2>

[0045] Based on the above-mentioned use of Zr-BTB-NH2 as a SO2 adsorption material, Zr-TPY nanosheets were further synthesized. The preparation method includes the following steps:

[0046] (1) Prepare the mixed solution:

[0047] Add 0.128 mmol of ZrCl4 and 28.2 mg of H3TPY to 30 ml of DMF. Add 4.0 ml of ultrapure water and 4.0 ml of formic acid to this mixed solution to obtain a mixed solution.

[0048] (2) Prepare Zr-TPY nanosheets

[0049] Perform water bath ultrasonic treatment on the mixed solution prepared in step (1) for 15 minutes. After the ultrasonic treatment, place the mixed solution in a reaction kettle for heating reaction. Among them, the heating temperature in the oven is 120 °C, and the heating time is 24 h. After the reaction, centrifuge and wash the obtained light brown suspension. Among them, the centrifuge speed is 8000 r / min, and the centrifuge time is about 5 min. At the same time, perform the centrifuge washing operation 5 times. Then dry the washed light brown suspension under vacuum at 150 °C to obtain Zr-TPY.

[0050] (3) Pretreatment of Zr-TPY material

[0051] Place the Zr-TPY powder in a vacuum drying oven, set the temperature to 100 °C, and dry for 12 hours to remove moisture and volatile substances. Cool the dried sample to room temperature under an inert gas atmosphere.

[0052] (4) SO2 adsorption test

[0053] Use an inert gas (N2) to purge the test system for 15 - 30 minutes to ensure that there are no impurity gases in the equipment. Uniformly place the pretreated Zr-TPY powder in the sample chamber of the adsorption test equipment to ensure good dispersion. Slowly introduce SO2 gas with a known concentration (1000 ppm) into the test equipment, ensure the gas flow is stable, set the test temperature (28 °C), keep the temperature constant, and record the temperature data.

[0054] Example 2 demonstrates the preparation method of the SO2 adsorption material based on Zr-TPY. However, the above scheme is not limited to the development of SO2 adsorption materials. In fact, this gas adsorption material can also be extended to other types of target gases.

[0055] <Morphology and Structure Characterization of Zr-BTB-NH2 and Zr-TPY>

[0056] A. Structure characterization

[0057] 6 mg each of the Zr-BTB-NH2 and Zr-TPY nanomaterials prepared in Example 1 and Example 2 were taken for XRD testing. Then, 1 mg each of the Zr-BTB-NH2 and Zr-TPY nanomaterials prepared in Example 1 and Example 2 were taken for infrared spectroscopy testing.

[0058] As Figure 1 shown in (a-b), the Zr-BTB-NH2 and Zr-TPY nanosheets exhibited similar characteristic peaks in the XRD pattern, indicating that these two materials had high crystallinity. At the same time, the appearance of diffraction peaks such as

[100] /

[010] showed good long-range order in the ab plane. The weaker peaks appearing in the

[001] direction indicated relatively poor long-range order along the c direction, which was consistent with the structural expectation of two-dimensional materials and reflected obvious orientation along the c-axis direction. As Figure 1 shown in (c-d), it can be seen from the infrared spectrum that the stretching vibration peak near 1680 cm -1 was attributed to the stretching vibration of the -C-N bond on H3TPY. As Figure 1 shown in (c-d), it can be seen from the infrared spectrum that the stretching vibration peak near 1505 cm -1 was attributed to the stretching vibration of -N-H on H3BTB-NH2, and the stretching vibration peak near 1654 cm -1 was attributed to the stretching vibration of the -C-N bond on H3TPY, indicating the stable existence of electron-rich nitrogen-containing groups in the MOF. In addition, the prepared MOF material exhibited excellent chemical stability and was able to withstand strong acid and strong base environments (as Figure 2 shown).

[0059] B. Morphology Characterization

[0060] 1 mL dispersions each of the Zr-BTB-NH2 and Zr-TPY nanomaterials prepared in Example 1 and Example 2 were added to centrifuge tubes, diluted with 5 mL of ethanol, and 6 μL each was taken and dropped onto silicon wafers for observation under a scanning electron microscope.

[0061] As Figure 3 shown, it can be seen from the scanning electron microscope (SEM) photos that the Zr-BTB-NH2 nanosheets stacked to form a uniform and dense film, and the surface showed good flatness and uniformity. In contrast, the morphology of Zr-TPY was relatively uneven, with obvious wrinkled structures.

[0062] <Specific Surface Areas of Zr-BTB-NH2 and Zr-TPY>

[0063] 80 mg each of the Zr-BTB-NH2 and Zr-TPY nanomaterials prepared in Example 1 and Example 2 were taken for N2 isothermal adsorption and desorption testing.

[0064] As Figure 4 shown, the specific surface areas of Zr-BTB-NH2 and Zr-TPY are 256.5 m 2 ·g -1 、483.7 m 2 ·g -1 , respectively, and the pore size distribution is mainly concentrated at 6.7 Å. The larger specific surface area provides more active sites for the nanosheets, thereby enhancing their SO2 adsorption capacity. This property gives Zr-BTB-NH2 and Zr-TPY potential advantages in gas adsorption applications and enables more effective removal of SO2 from the environment.

[0065] <SO2 Adsorption Performance of Zr-BTB-NH2 and Zr-TPY>

[0066] Take 100 mg each of the Zr-BTB-NH2 and Zr-TPY nanomaterials prepared in Example 1 and Example 2 for SO2 adsorption testing.

[0067] The specific gas adsorption process is as follows. First, place the Zr-BTB-NH2 and Zr-TPY powders in a vacuum drying oven, set the temperature to 100 °C, and dry for 12 hours to remove moisture and volatile substances. Subsequently, cool the dried samples to room temperature under an inert gas atmosphere. Use an inert gas (N2) to purge the adsorption test system for 15 - 30 minutes to ensure that there are no impurity gases in the equipment. Place the pretreated Zr-BTB-NH2 and Zr-TPY powders evenly in the sample chamber of the adsorption test equipment to ensure good dispersion.

[0068] After the samples are placed, slowly introduce 1000 ppm of SO2 gas, set the flow rate to the required value (such as 50 mL·min -1 ), and continuously introduce it for 4 - 6 hours to ensure that the samples are fully exposed to the SO2 gas. Use a gas analyzer to monitor the change in SO2 concentration in the sample chamber in real time, record the initial concentration and the concentration data at different time points during the adsorption process, record every 10 minutes until adsorption equilibrium.

[0069] As Figure 5 shown, at 300 K and 1 bar, the maximum SO2 adsorption capacities of Zr-BTB-NH2 and Zr-TPY are 39.3 cm 3 ·g -1 (1.75 mmol g -1 ) and 66.3 cm 3 ·g -1 (2.96 mmol g -1The adsorption capacity of Zr-TPY is higher than the previously reported maximum adsorption capacity of 2.29 mmol⋅g for CPL-1-NH₂ constructed with aminopyrazine-2,3-bidentcarboxylic acid at 298 K and 1 bar. -1 (Separation and Purification Technology, 2022, 295, 121337.), NPC-3 (maximum adsorption capacity 2.15 mmol⋅g) -1 NPC-2 (maximum adsorption capacity 1.44 mmol⋅g) -1 ) and NPC-1 (maximum adsorption capacity 1.08 mmol⋅g) -1 (Chemical Engineering Journal 2016, 290, 116-124.) and other materials. Meanwhile, it was compared with nitrogen-free Zr-BTBMOF materials (which showed a SO2 saturation adsorption capacity of 22.5 cm⁻¹ at 300 K and 1 bar). 3 ·g -1 The adsorption capacity for SO2 was significantly improved. The hysteresis loop between the adsorption and desorption isotherms can be attributed to the strong interaction between SO2 and the nitrogen-containing framework material, which also verifies the design concept of achieving efficient SO2 capture by introducing nitrogen-containing groups into the framework material.

[0070] It is understood that the embodiments of the system described above are merely illustrative, and the units described as separate components may or may not be physically separated; they may be located in one place or distributed across different network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any inventive effort.

[0071] Furthermore, those skilled in the art should understand that in the application documents of this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0072] Numerous specific details are set forth in the specification of embodiments of the present invention. However, it should be understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification. Similarly, it should be understood that, in order to streamline the disclosure of embodiments of the present invention and aid in the understanding of one or more of the various inventive aspects, various features of the embodiments of the present invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the present invention. However, this method of disclosure should not be construed as reflecting an intention that the claimed embodiments of the present invention require more features than those expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all features of a single foregoingly disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the present invention.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a class of electron-rich metal-organic framework SO2 adsorbents, characterized in that, The method includes the following steps: ZrCl4 and H3BTB-NH2 or H3TPY were added to DMF to obtain a mixed solution. Ultrapure water and formic acid were added to the mixed solution, and the mixture was subjected to ultrasonic treatment. After ultrasonic treatment, the mixture was placed in a reaction vessel and heated. After reacting for 24 h, the resulting suspension was centrifuged and washed multiple times to finally obtain a uniformly dispersed Zr-BTB-NH2 or Zr-TPY nanosheet suspension resistant to strong acids and strong bases. The structure of H3BTB-NH2 is as follows: ； The structure of H3TPY is as follows: ； The molar ratio of ZrCl4 to H3BTB-NH2 is 1.9:1-2.0:1, and the molar ratio of ZrCl4 to H3TPY is 1.9:1-2.0:

1.

2. The method for preparing a type of electron-rich metal-organic framework SO2 adsorbent as described in claim 1, characterized in that: The amount of DMF solvent added is 30.0-30.2 ml.

3. The method for preparing a type of electron-rich metal-organic framework SO2 adsorbent as described in claim 1, characterized in that: The amount of ultrapure water added is 4.0-4.2 ml; the amount of formic acid added is 4.0-4.2 ml.

4. The method for preparing a type of electron-rich metal-organic framework SO2 adsorbent as described in claim 1, characterized in that: The ultrasound power is 200-300 W, and the cumulative ultrasound time is 15-20 min.

5. The method for preparing a type of electron-rich metal-organic framework SO2 adsorbent as described in claim 1, characterized in that: The heating temperature is 120 ℃.

6. A method for preparing a type of electron-rich metal-organic framework SO2 adsorbent as described in claim 1, characterized in that: The centrifugation speed is 8000-10000 r / min, the centrifugation time is 5-7 min, and the centrifugation washing operation is no less than 5 times.

7. An application of Zr-BTB-NH2 or Zr-TPY nanosheets prepared by the method described in claim 1 for SO2 gas adsorption, characterized in that: Zr-BTB-NH2 or Zr-TPY nanosheet suspensions were dried and used as SO2 adsorbents.

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