Hydrogen-bonded organic framework material for flue gas desulfurization and preparation method and application thereof

Abstract

A kind of hydrogen bond organic framework material for flue gas desulfurization and its preparation method and application, it relates to flue gas desulfurization technical field, it is to place the activated crystal powder in carbon dioxide atmosphere under the condition of minus 87 ℃ to minus 20 ℃, 6-12 hours are stationary. 1-2 hours are extracted by vacuum pump, carbon dioxide molecule is removed, and the hydrogen bond organic framework material is obtained. Technical effect is, the obtained hydrogen bond organic framework material shows specific adsorption to sulfur dioxide, and hardly adsorbs other components such as carbon dioxide, nitrogen, methane and the like in flue gas. The material itself has good hydrophobicity, the adsorption amount of water is extremely low, greatly reduces the influence of water vapor in real flue gas environment on the adsorption capacity of material, and shows high water stability and acid-base stability, which is beneficial to the application in real flue gas environment. And the material has high cycle stability.

Description

Technical Field

[0001] This invention relates to the field of flue gas desulfurization technology, specifically to a hydrogen-bonded organic framework material, its preparation method, and its application in flue gas desulfurization. Background Technology

[0002] Flue gas desulfurization (FGD) is a key technology for reducing sulfur dioxide (SO2) content in industrial flue gas. Sulfur dioxide is one of the main pollutants produced when burning fuels such as coal, causing serious impacts on the environment and human health. To reduce sulfur dioxide emissions, FGD technology is widely used in industrial sectors such as power plants, steel mills, and chemical plants. FGD processes play a crucial role in the industrial and energy sectors. With the acceleration of industrialization and the growth of energy demand, sulfur dioxide released from burning fossil fuels has become a significant source of environmental pollution. This gas not only harms human health but also has a considerable impact on the atmospheric environment, natural ecosystems, and buildings.

[0003] The emergence and development of flue gas desulfurization (FGD) technology has filled a significant gap in environmental protection. By utilizing various desulfurization technologies, sulfur dioxide can be effectively removed from flue gas, reducing its harmful effects on the environment. This not only meets international environmental protection standards but is also a necessary measure to safeguard public health and promote sustainable development.

[0004] Currently, flue gas desulfurization methods mainly include wet desulfurization and dry desulfurization. Wet desulfurization includes: the lime-gypsum method (a common method), where lime slurry is sprayed into the flue gas; sulfur dioxide reacts with the lime to form calcium sulfide, ultimately forming gypsum precipitate. This method is highly efficient at removing sulfur dioxide, but requires the treatment of gypsum waste. The lime-emulsion method suspends lime in an emulsion, forming fine particles, increasing the contact area between the lime and sulfur dioxide in the flue gas, thus improving desulfurization efficiency. The lime-dual-alkali method combines lime with other alkaline substances (such as sodium hydroxide or soda ash) to enhance the desulfurization effect. Dry desulfurization includes: activated carbon adsorption, which uses activated carbon to adsorb sulfur dioxide from the flue gas, and then regenerates the saturated activated carbon for reuse. Dry reactor methods use fixed-bed or moving-bed reactors, employing fixed adsorbents (such as calcium oxide or sodium oxide) to remove sulfur dioxide from the flue gas.

[0005] Hydrogen-bonded organic frameworks (HBOFs) are a novel class of porous materials with the following characteristics: Hydrogen bond construction: The construction of HBOFs relies on hydrogen bonding, typically forming a network structure by connecting organic molecules through hydrogen bonds. This moderately strong hydrogen bond interaction endows the materials with good structural stability and controllability. Porosity: HBOFs possess abundant pore structures, which can be used for adsorbing and storing gas molecules, catalyzing reactions, etc. The pore size, shape, and distribution can be controlled by rationally designing the structure of organic molecules to meet different application requirements. Tunability and controllability: Since HBOFs are formed through the self-assembly of organic molecules via hydrogen bonds, the properties of the materials can be controlled by synthesizing the structure of organic molecules. This tunability and controllability gives them broader application potential. Selective adsorption performance: Because the pore design can be optimized for specific molecules or molecular size ranges, HBOFs often exhibit high selective adsorption capacity for specific gases or solvents, making them suitable for gas separation, energy storage, and other fields. Environmentally friendly and sustainable, hydrogen-bonded organic frameworks (HBOFs) are typically composed of natural or synthetic organic molecules. Their synthesis methods are relatively environmentally friendly, and they can be sustainably utilized through reuse and regeneration. Due to their unique structural characteristics and diverse application potential, HBOFs have shown broad application prospects in gas adsorption, separation, catalysis, drug release, and energy storage, and are attracting increasing attention and research from scientists and engineers. How to prepare HBOFs with good stability, high sulfur dioxide adsorption capacity, and high sulfur dioxide / carbon dioxide adsorption / separation selectivity at low cost is a challenging technical problem. Summary of the Invention

[0006] Further research on the activated microcrystals (organic soft porous framework material) prepared in Chinese invention patent CN114907230 revealed that this material exhibits specific adsorption for acetylene, while showing almost no adsorption for several other common gases. To overcome the current problems of poor selectivity, complex material preparation, and high cost in industrial separation of sulfur dioxide / carbon dioxide, this invention utilizes a carbon dioxide-induced hydrogen-bonded organic framework material method. This two-step method completes the preparation of hydrogen-bonded organic framework materials, resulting in materials with ultra-high stability, high sulfur dioxide / carbon dioxide adsorption selectivity, simple preparation, high cycle stability, and recyclability.

[0007] Based on the above technical concept, this invention is based on the activated microcrystals (organic soft porous framework material) prepared in patent CN114907230, and achieves the purpose of this invention through the following technical solutions.

[0008] The technical solution adopted in this invention is as follows: under the conditions of -87℃ to -20℃, the activated microcrystals (organic soft porous framework material) prepared in patent CN114907230 are placed in a carbon dioxide atmosphere of one atmosphere and left to stand for 6-12 hours. Then, a vacuum pump is used to evacuate for 1-2 hours to remove carbon dioxide molecules, thereby obtaining the hydrogen-bonded organic framework material.

[0009] Furthermore, a preferred preparation method of the present invention is as follows:

[0010] (1) At -20℃, the activated crystal powder was placed in a carbon dioxide atmosphere and left to stand for 6 hours.

[0011] (2) Use a vacuum pump to evacuate for 1 hour to remove carbon dioxide molecules and obtain the hydrogen-bonded organic framework material.

[0012] (3) The material after gas adsorption is completed can be regenerated through steps (1) and (2).

[0013] The organic soft porous framework material of the present invention has the following structural formula:

[0014]

[0015] Furthermore, the present invention provides the use of the obtained hydrogen-bonded organic framework material for flue gas desulfurization, which can be used for the adsorption of sulfur dioxide in flue gas.

[0016] Furthermore, the material exhibits an adsorption capacity of 151 cm⁻¹ for sulfur dioxide at 25°C and 1 bar. 3 / g.

[0017] The technical effect of this invention is that by adjusting and changing the technical means in this invention, a hydrogen-bonded organic framework material for flue gas desulfurization can be prepared, and the obtained hydrogen-bonded organic framework material has the following characteristics:

[0018] (1) The hydrogen-bonded organic framework material prepared by this method exhibits specific adsorption of sulfur dioxide, while it has almost no adsorption of other components in flue gas such as carbon dioxide, nitrogen, and methane.

[0019] (2) Because the material itself has good hydrophobicity, the amount of water adsorbed is extremely low, which greatly reduces the influence of water vapor on the material's adsorption capacity in the real flue gas environment.

[0020] (3) The breakthrough experiment of the material under simulated real flue gas environment shows that the prepared material has a good separation effect on sulfur dioxide and carbon dioxide.

[0021] (4) The material exhibits extremely high water and acid-base stability, which is beneficial for application in real flue gas environments.

[0022] (5) The material maintains a good structure after multiple adsorption / desorption cycles, indicating that it has high cycle stability. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the preparation process of the hydrogen-bonded organic framework material of the present invention.

[0024] Figure 2 This is the single-crystal structure of the hydrogen-bonded organic framework material obtained in this invention.

[0025] Figure 3 This is the adsorption curve of different gas components at 25°C according to the present invention.

[0026] Figure 4 This invention provides a calculation of the selectivity of sulfur dioxide / carbon dioxide.

[0027] Figure 5 This is the water adsorption / desorption isotherm at 25°C for this invention.

[0028] Figure 6 This invention relates to the single-crystal to single-crystal transformation after the hydrogen-bonded organic framework adsorbs sulfur dioxide.

[0029] Figure 7 Powder X-ray diffraction pattern for water stability testing of this invention.

[0030] Figure 8 This is the experimental curve of simulated flue gas components (dry) at 25°C according to the present invention.

[0031] Figure 9 This is the experimental curve of the simulated real flue gas components (moist) penetrating the column at 25°C according to the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be further illustrated below through embodiments.

[0033] Example 1

[0034] Preparation of hydrogen-bonded organic framework materials; see appendix for preparation process. Figure 1 The preparation method of hydrogen-bonded organic framework microcrystals involves exposing activated microcrystals to a CO2 atmosphere at approximately 1 bar and 195 K for 12 hours, followed by a 2-hour vacuum treatment to obtain hydrogen-bonded organic framework microcrystals (HOF-NKU-1). The structure of this material is shown in the attached figure. Figure 2 As shown.

[0035] Single-component gas adsorption-desorption experiment

[0036] See appendix Figure 3 To test the adsorption and separation performance of the synthesized hydrogen-bonded organic framework material, single-component adsorption isotherms for sulfur dioxide, carbon dioxide, nitrogen, oxygen, and methane were performed using the aforementioned hydrogen-bonded organic framework material as an adsorbent. 180 mg of adsorbent was used, and the adsorption temperature was set to 25°C. The tests showed that at 25°C and 1 bar, the adsorption capacity for sulfur dioxide reached 151 cm⁻¹. 3 / g, the adsorption capacity of carbon dioxide is only 15cm³. 3 / g.

[0037] Example 2

[0038] See appendix Figure 4 To test the adsorption selectivity of the synthesized hydrogen-bonded organic framework material, the adsorption data were used to calculate the sulfur dioxide / carbon dioxide selectivity.

[0039] Example 3

[0040] See appendix Figure 5 To test the water adsorption capacity of the synthesized hydrogen-bonded organic framework material, a single-component adsorption / desorption isotherm of water vapor was performed using the adsorbent. 210 mg of adsorbent was used, and the adsorption temperature was set to 25°C. At 25°C and 1 bar, the water adsorption capacity was only 17 mg / g, exhibiting a very low water adsorption capacity.

[0041] Example 4

[0042] See appendix Figure 6 To investigate the adsorption mechanism of sulfur dioxide by the synthesized hydrogen-bonded organic framework material, the crystals were removed from the scintillation bottle and placed in the air to allow the dichloromethane to slowly evaporate. After standing for 24 hours, the single crystals were analyzed to obtain the data of the activated single crystals. A portion of the activated single crystals was placed in a sulfur dioxide atmosphere for 6 hours to analyze the single crystal structure. The single crystal data showed that it exhibited a transformation from single crystal to single crystal and then back to single crystal.

[0043] Example 5

[0044] See appendix Figure 7 To test the stability of the synthesized hydrogen-bonded organic framework material, the prepared hydrogen-bonded organic framework material was placed in water, 12M NaOH solution, 12M HCl solution, and air for two weeks, respectively. The powder XRD was tested and it was observed that its structure did not change, indicating good stability.

[0045] Example 6

[0046] See appendix Figure 8In this embodiment, 1.0224 g of HOF-NKU-1 was packed into a quartz tube with an inner diameter of 6 mm. Before adsorption testing, the sample was activated at 298 K for 6 hours with helium (He) flowing at a rate of 20 mL / min to ensure the removal of any impurities. The gas mixture used in the adsorption process consisted of SO2, CO2, O2, and N2 in a volume ratio of 0.3:15:3.5:81.2, with a concentration of 3000 ppm. After a two-hour gas preparation phase, this gas mixture was introduced into the tube, and the wet-path carrier gas was thoroughly mixed with the SO2, CO2, O2, and N2 gases. The effluent from the adsorption bed was continuously monitored using a gas mass spectrometer. Test curves were obtained using software. The tests showed significant separation of SO2, CO2, O2, and N2.

[0047] Example 7

[0048] See appendix Figure 9 To test the actual separation effect of this type of hydrogen-bonded organic framework material on flue gas, the above-synthesized adsorbent was used. A column packed with HOF-NKU-1 was pre-saturated with a helium flow containing 3% H2O at a rate of 20 mL / min until breakthrough occurred. A breakthrough test of a SO2 / CO2 / N2 / O2 mixture was conducted under humid conditions. In this example, 1.0224 g of HOF-NKU-1 was packed into a quartz tube with an inner diameter of 6 mm. Before adsorption testing, the sample was activated at 298 K for 6 hours with helium (He) flowing at a rate of 20 mL / min to ensure the removal of any impurities. The gas mixture used in the adsorption process consisted of SO2, CO2, O2, and N2 in a volume ratio of 0.3:15:3.5:81.2 and a concentration of 3000 ppm. After a two-hour gas preparation phase, this gas mixture was introduced into the tube, and the wet path carrier gas was thoroughly mixed with the SO2, CO2, O2, and N2 gases. The effluent from the adsorption bed was continuously monitored using a gas analysis mass spectrometer. Test curves were generated using software. Tests showed significant separation efficiency for SO2, CO2, O2, and N2.

[0049] Example 8

[0050] Unlike Example 1, the method for preparing microcrystals in this example is to expose the activated microcrystals to a CO2 atmosphere of approximately 1 bar and 253 K for 6 hours, and then perform a vacuum treatment for 1 hour to finally obtain hydrogen-bonded organic framework microcrystals.

[0051] Example 9

[0052] Unlike Examples 1 and 8, the method for preparing microcrystals in this example is to expose the activated microcrystals to a CO2 atmosphere of approximately 1 bar and 220 K for 8 hours, followed by a vacuum treatment for 1 hour, ultimately obtaining hydrogen-bonded organic framework microcrystals.

[0053] Based on the above embodiments, the present invention is as follows: Figure 1 As shown, the hydrogen-bonded organic framework material obtained by patent CN114907230 was obtained by placing the organic soft porous framework material in a carbon dioxide atmosphere at one atmosphere for a certain period of time, and then evacuating it with a vacuum pump. Furthermore, the present invention verified the single-component adsorption of sulfur dioxide, carbon dioxide, nitrogen, oxygen, and methane on the obtained hydrogen-bonded organic framework material, and also tested the actual separation effect of this type of hydrogen-bonded organic framework material on flue gas. The experimental results show that the material obtained by the present invention exhibits specific adsorption of sulfur dioxide, while showing almost no adsorption of other components in the flue gas such as carbon dioxide, nitrogen, and methane. Penetration experiments under simulated real flue gas conditions show that the prepared material has good separation effect on sulfur dioxide and carbon dioxide. Performance tests of the hydrogen-bonded organic framework material obtained by the present invention verified that the material itself has good hydrophobicity, which can greatly improve the adsorption performance of sulfur dioxide in flue gas in a flue gas environment. Furthermore, the material maintains a good structure after multiple adsorption / desorption cycles, exhibiting strong water stability and acid-base stability, which is beneficial for application under real flue gas conditions.

Claims

1. A method for preparing a hydrogen-bonded organic framework material for flue gas desulfurization, characterized in that: Organic soft porous framework materials were subjected to temperatures ranging from -87°C to -20°C. o Activation is performed under C conditions. The activated crystal powder is placed in a carbon dioxide atmosphere at one atmosphere and allowed to stand for 6-12 hours. Then, a vacuum pump is used to remove carbon dioxide molecules for 1-2 hours, thus obtaining the hydrogen-bonded organic framework material. The structural formula of the organic soft porous framework material is as follows: 。 2. A hydrogen-bonded organic framework material for flue gas desulfurization, characterized in that: It is prepared by the method described in claim 1.

3. The use of the hydrogen-bonded organic framework material for flue gas desulfurization as described in claim 2, characterized in that: Used for the adsorption of sulfur dioxide in flue gas.

4. The use of the hydrogen-bonded organic framework material for flue gas desulfurization according to claim 3, characterized in that: The material achieved an adsorption capacity of 151 cm⁻¹ for sulfur dioxide at 25°C and 1 bar. 3 / g.

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