A method for treating industrial exhaust gas

Abstract

This invention discloses a method for treating industrial exhaust gas, comprising the following steps: using 100-3000h ‑1 Industrial exhaust gas containing fluorinated greenhouse gases, including at least hexafluoroethane, is introduced at air velocity into a trap containing a modified adsorbent. The modified adsorbent adsorbs the fluorinated greenhouse gases in the incoming industrial exhaust gas at an adsorption temperature of 5–80°C. Adsorption stops when the concentration of hexafluoroethane in the outgoing industrial exhaust gas drops to 0.1–1000 ppm. The surface of the modified adsorbent is loaded with a hydrophobic material. The treatment method of this invention is simple, has low operating energy consumption, and can achieve efficient capture of fluorinated greenhouse gases in normal temperature and high humidity environments, reducing the concentration of fluorinated greenhouse gases in industrial exhaust gas.

Description

Technical Field

[0001] This invention relates to the field of greenhouse gas emission reduction materials technology, and in particular to a method for treating industrial exhaust gas. Background Technology

[0002] With increasing industrialization and human activity, the global greenhouse effect has become increasingly severe, and various extreme weather disasters occur frequently, posing a serious threat to the survival of human society. Fluorocarbons are a class of man-made important greenhouse gases with extremely strong greenhouse effects and extremely long atmospheric lifetimes, such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3), which are included in the emission reduction list under the Kyoto Protocol.

[0003] Fluorinated greenhouse gases have wide applications across various industries. HFCs are commonly used as refrigerants, foaming agents, fire extinguishing agents, etching agents, and cleaning agents. SF6, besides being used as an insulating gas, is also used in semiconductor manufacturing along with NF3. Perfluorinated carbons are a class of hydrocarbons in which all hydrogen atoms are replaced by fluorine atoms. Here, we mainly refer to carbon tetrafluoride (CF4), hexafluoroethane (C2F6), octafluoropropane (C3F8), and perfluorobutane (n-C4F6). 10 PFCs, such as fluorinated carbon dioxide (FCs), are classified as key globally regulated greenhouse gases containing fluorine. Compared to greenhouse gases like CO2, they have an extremely high global warming potential (GWP). 100 ) and atmospheric lifetime. Among them, the GWP of C2F6 100 With a concentration of 12400, C2F6 is widely used in semiconductor manufacturing, flat panel display production, and other processes. In recent years, its emissions have been increasing, leading to a gradual rise in atmospheric concentrations. During semiconductor manufacturing, C2F6 is primarily used as a dry etching gas and cleaning agent, with an ionization rate of only about 10%. The remaining C2F6 is released into the atmosphere, which not only wastes this highly valuable resource but also increases its atmospheric concentration, exacerbating the greenhouse effect. Recycling and utilizing C2F6 and other fluorinated greenhouse gases could not only mitigate the global greenhouse effect but also yield significant economic benefits.

[0004] Developing efficient fluorinated greenhouse gas capture technologies is of significant strategic importance. This technology can effectively reduce greenhouse gas emissions from various industries and also enable the recycling of fluorine resources.

[0005] There are few reports on existing technologies for treating fluorinated greenhouse gases.

[0006] Chinese patent CN1185440C discloses a method and industrial apparatus for treating organohalides by plasma incineration. The temperature of this method can be arbitrarily adjusted within the range of 850℃ to 3000℃. At 1500℃, trifluoromethane can be completely decomposed in a few milliseconds. However, the electric heater of this method is prone to coking, making cleaning difficult, and it will generate a large amount of fluoride-containing wastewater.

[0007] Chinese patent CN107084399B discloses a burner for a fluorine-containing waste gas incinerator and a method for treating fluorine-containing waste gas incineration. The method has high treatment efficiency and complete combustion of fluorine-containing waste gas, but the fluorine-containing waste gas will corrode the internal parts of the equipment, and scale will still form on the inner wall of the incinerator.

[0008] Chinese patent CN106241800B discloses an activated carbon specifically designed for adsorbing carbon tetrafluoride, prepared from anthracite powder and bituminous coal-based activated carbon powder. This material has high strength and high bulk density, but its CF4 adsorption capacity is low, making it unsuitable for capturing large quantities of CF4 gas.

[0009] Industrial exhaust gases containing fluorinated greenhouse gases emitted during semiconductor manufacturing processes are washed with water to remove particulate pollutants and acidic gases. This process greatly increases the humidity of the industrial exhaust gases. During the capture process, water vapor occupies the adsorption sites on the adsorbent, reducing the amount of fluorinated greenhouse gases adsorbed. For adsorbents with poor water resistance, it may even damage the material's skeletal structure. This places higher demands on fluorinated greenhouse gas capture technology. Summary of the Invention

[0010] In view of the shortcomings and defects of the existing technology, the present invention proposes a method for treating industrial exhaust gas. The method has a simple process, low operating energy consumption, high adsorption capacity, good stability and strong hydrophobicity of the adsorbent. It can achieve efficient treatment of industrial exhaust gas under normal temperature and high humidity environment, which can not only realize the recovery and utilization of fluorine-containing greenhouse gases, but also mitigate the global greenhouse effect and protect the environment.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] A method for treating industrial exhaust gas includes the following steps: using 100-3000h -1 Industrial exhaust gas containing fluorinated greenhouse gases is introduced at air velocity into a trap containing a modified adsorbent, wherein the fluorinated greenhouse gases include at least hexafluoroethane gas; the modified adsorbent adsorbs the fluorinated greenhouse gases in the incoming industrial exhaust gas at an adsorption temperature of 5–80°C, and adsorption stops when the concentration of hexafluoroethane in the outgoing industrial exhaust gas drops to 0.1–1000 ppm; the surface of the modified adsorbent is loaded with a hydrophobic material.

[0013] In addition to hexafluoroethane, the fluorinated greenhouse gas also includes at least one of CF4, SF6, C3F8, CHF3, CH2F2, C4F6, C4F8, and NF3; preferably, the fluorinated greenhouse gas also includes at least one of CF4, C3F8, CHF3, CH2F2, C4F6, and C4F8.

[0014] The industrial exhaust gas described in this invention is industrial exhaust gas containing fluorine-containing greenhouse gases discharged after the etching and cleaning stages in semiconductor manufacturing and flat panel display production. It also includes at least one of N2, NH3, H2, Ar, O2, SiH4, CO, CO2, HBr, Cl2, N2O, and H2O.

[0015] This invention can reduce the concentration of fluorinated greenhouse gases in industrial exhaust gas to 0.1-1000 ppm, helping semiconductor manufacturing companies achieve their carbon reduction targets.

[0016] Specifically, online mass spectrometry is used to monitor the concentration of fluorinated greenhouse gases such as hexafluoroethane in the effluent industrial exhaust gas in real time. Adsorption is stopped when the concentration of hexafluoroethane and other fluorinated greenhouse gases decreases to a target value. The target value for the concentration of hexafluoroethane and other fluorinated greenhouse gases is typically 0.1–1000 ppm; preferably, adsorption is stopped when the concentration of hexafluoroethane and other fluorinated greenhouse gases is 0.1–100 ppm; more preferably, adsorption is stopped when the concentration of hexafluoroethane and other fluorinated greenhouse gases is 0.1–10 ppm.

[0017] In the industrial exhaust gas treatment method of the present invention, it is necessary to reasonably control the initial concentration of fluorinated greenhouse gas flowing into the industrial exhaust gas. If the initial concentration of fluorinated greenhouse gas is too high, it will cause the adsorbent to be overloaded, reducing the adsorbent's capture efficiency of fluorinated greenhouse gas. If the initial concentration of fluorinated greenhouse gas is too low, it will result in a lower contact area between the fluorinated greenhouse gas and the adsorbent, which will also reduce the adsorbent's capture efficiency of fluorinated greenhouse gas.

[0018] The industrial exhaust gas described in this invention has a high concentration of water vapor, which competes with fluorine-containing greenhouse gases for adsorption, occupying the adsorption sites of the adsorbent and thus reducing the adsorption selectivity of fluorine-containing greenhouse gases. In some cases, some water-unstable adsorbents may even hydrolyze in the presence of water vapor, causing the framework to collapse.

[0019] In the treatment method of this invention, the concentration of fluorinated greenhouse gas in the industrial exhaust gas is 0.1-10%. When the concentration of fluorinated greenhouse gas is greater than 10%, it can be diluted with an inert gas to reduce the concentration of fluorinated greenhouse gas to 0.1-10%; preferably, the concentration of fluorinated greenhouse gas is reduced to 1-5%.

[0020] The concentration of water vapor in the industrial exhaust gas is 0-10%. When the concentration of water vapor is greater than 10%, it can be reduced to 0-10% through drying treatment; preferably, the concentration of water vapor is reduced to 0-5%.

[0021] Preferably, the adsorption temperature is 20–30°C, the adsorption pressure is 0.05–0.15 MPa, and the space velocity is 1000–2000 h⁻¹. -1 .

[0022] The modified adsorbent is a metal-organic framework material with a surface-loaded hydrophobic material. The hydrophobic material is a porous aromatic framework material comprising 0.1 wt.% to 30 wt.%, preferably 1 to 10 wt.%. The porous aromatic framework material is PAF-56, which has strong hydrophobicity. As a material for constructing a surface hydrophobic protective layer, it effectively prevents water vapor in the mixed gas from rapidly adhering to the adsorption sites of the adsorbent, thus improving the selectivity of the adsorption of fluorinated greenhouse gases such as hexafluoroethane against water vapor. The thickness of the hydrophobic material is 200–1000 nm, preferably 200–400 nm.

[0023] The metal-organic framework material is constructed from aluminum ions and unsaturated dicarboxylic acid ligands. Specifically, the unsaturated dicarboxylic acid ligands are selected from... At least one of the following, R is selected from at least one of H, OH, CH3, NO2, NH2, F, Cl, Br or I.

[0024] Unlike greenhouse gases such as carbon dioxide, fluorinated greenhouse gases contain stable CF bonds in their structure, resulting in relatively stable chemical properties and weaker interactions with adsorbent surfaces. They are less prone to chemisorption through electron transfer. Therefore, the adsorption treatment of fluorinated greenhouse gases primarily relies on physical adsorption, with van der Waals forces playing a dominant role.

[0025] The modified adsorbent structure used in this invention is composed of AlO6. -The polyhedrons form one-dimensional rhombic channels composed of metal octahedral chains sharing corners. The pore size matches the molecular dynamics diameter of fluorinated greenhouse gases. Al and -OH groups are connected at the vertices, and the channels contain abundant, orderly arranged hydroxyl groups, exhibiting strong HF interactions with perfluorinated carbon, particularly hexafluoroethane. A porous aromatic framework material, PAF-56, is coated onto the modified adsorbent surface. PAF-56's strong hydrophobicity and large pore size facilitate the diffusion and adsorption of fluorinated greenhouse gases, enhancing the overall hydrophobicity of the modified adsorbent. The precise pore channel control mechanism, abundant adsorption sites, and efficient surface hydrophobic channels enable highly efficient capture of fluorinated greenhouse gases when they come into contact with the modified adsorbent described in this invention, due to the high affinity of the adsorption sites for the gases.

[0026] In the treatment of industrial exhaust gases, modified adsorbents can be placed on a fixed bed. Fluorine-containing greenhouse gases diffuse slowly within the pores of the modified adsorbent, exhibit strong interaction forces, and are adsorbed in large quantities, thus becoming enriched in the fixed bed. Gases such as nitrogen have weak interaction forces with the adsorbent and diffuse quickly within the pores, resulting in low adsorption amounts. The hydrophobic protective layer on the surface of the modified adsorbent can effectively reduce the adsorption amount of water vapor at the adsorption sites, thereby increasing the adsorption capacity for fluorine-containing greenhouse gases.

[0027] The modified adsorbent of this invention has a pore size that matches the molecular dynamic diameter of hexafluoroethane, a fluorine-containing greenhouse gas. Furthermore, the adsorbent pores contain abundant -OH groups, which can generate strong HF or HO interactions with gas molecules. Therefore, in addition to adsorbing hexafluoroethane, it also exhibits good adsorption effects on greenhouse gases such as CO2, CF4, N2O, SF6, NF3, and C3F8, whose molecular dynamic diameters are close to or smaller than that of hexafluoroethane.

[0028] The present invention also provides a method for preparing the modified adsorbent, specifically comprising the following steps:

[0029] A. Preparation of metal-organic framework materials: Aluminum salt, unsaturated dicarboxylic acid ligand, and aprotic polar solvent are added to a reaction vessel at a molar ratio of 1:(1-5):(20-100) and mixed evenly to form a suspension; 0.05-0.35 mol of organic acid is added to the suspension, and the suspension is heated to 110-180°C and stirred for 24-96 h; intermediate product A is obtained through post-treatment, wherein intermediate product A is a metal-organic framework material constructed from aluminum ions and unsaturated dicarboxylic acid ligand;

[0030] B. Hydrophobic material loaded on the surface of the modified adsorbent: The intermediate product A, aluminum salt, nitrogen-containing organic matter and polycyclic aromatic hydrocarbon are dissolved in 5-50 mL of organic solvent at a mass ratio of 1:(2-10):(1-5):(1-5), mixed evenly, filtered, washed, purified and dried to obtain the final product B, which is the modified adsorbent.

[0031] Preferably, in step A, the molar ratio of aluminum salt, unsaturated dicarboxylic acid ligand, and aprotic polar solvent is 1:(2-3):(60-80).

[0032] Preferably, in step B, the mass ratio of intermediate product A, aluminum salt, nitrogen-containing organic compound and polycyclic aromatic hydrocarbon is 1:(3-5):(2-3):(2-3).

[0033] The post-processing includes operations such as filtration, centrifugation, washing, and drying.

[0034] The aluminum salt simply needs to provide aluminum ions. Preferably, the aluminum salt is selected from at least one of aluminum chloride, aluminum sulfate, aluminum nitrate, and aluminum silicate.

[0035] The aprotic polar solvent has strong polarity, which enables the unsaturated dicarboxylic acid ligands and aluminum salts to be dispersed more uniformly. Preferably, the aprotic polar solvent is selected from at least one of acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, and 1,3-dimethyl-2-imidazolinone.

[0036] The organic acid has an acidity of pKa = 1 to 4. Preferably, the organic acid is selected from at least one of formic acid, acetic acid, propionic acid, oxalic acid, and benzoic acid.

[0037] The organic solvent is selected from at least one of methanol, ethanol, propanol, acetone, and chloroform; the nitrogen-containing organic compound is selected from at least one of melamine, cyanuric chloride, urea, and biuret; and the polycyclic aromatic hydrocarbon is selected from at least one of biphenyl, p-terphenyl, bibenzoyl, and dimethyl biphenylate.

[0038] The modified adsorbent of this invention can be vacuum activated before use to further improve its performance in capturing fluorine-containing greenhouse gases. Specifically, the modified adsorbent is used in a 10-100 mesh form, and the activation treatment includes the following steps: the activation temperature is 80-150℃, the activation pressure is -0.01--0.1 MPa, the activation heating rate is 2-10℃ / min, and the activation time is 5-20 h.

[0039] Under normal circumstances, the modified adsorbent described in this invention can be desorbed by vacuuming and can be recycled after regeneration. Specifically, in the treatment method of this invention, when the concentration of fluorinated greenhouse gases such as hexafluoroethane in the outflowing industrial exhaust gas cannot be reduced to the target value, adsorption is stopped, and the pipeline is switched to a standby trap containing the modified adsorbent. The adsorbent bed in the original trap is then regenerated. The regeneration process includes the following steps: regeneration temperature of 80–150°C, regeneration pressure of -0.01–-0.1 MPa, and regeneration time of 0.5–3 hours.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] 1. The processing method described in this invention is simple in process and has low energy consumption. It can efficiently capture fluorine-containing greenhouse gases such as hexafluoroethane in industrial exhaust gas and can be widely used for the capture and recovery of fluorine-containing greenhouse gases in industrial exhaust gas.

[0042] 2. The modified adsorbent described in this invention has a simple synthesis process, high adsorption capacity for fluorine-containing greenhouse gases such as hexafluoroethane, stable chemical properties, strong hydrophobicity, and is easy to regenerate and can be recycled.

[0043] 3. The processing method described in this invention has a wide range of applications and can be used in environments with normal temperature and high humidity. Attached Figure Description

[0044] Appendix Figure 1 The adsorption and breakthrough results of the modified adsorbent prepared for Example 1 on a 10 mol.% C2F6 / N2 mixed gas. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements, and equivalents that may be included within the scope of the claims.

[0046] Preparation Example 1

[0047] A. Preparation of metal-organic framework materials: Add a mixture of 10 mmol AlCl3, 20 mmol fumaric acid and 60 mL dimethyl sulfoxide to a beaker and stir until a suspension is formed; add 5 mL oxalic acid to the suspension, heat the suspension to 150 °C, stir for 72 h, centrifuge the precipitate 3 times, wash with ethanol 3 times, and dry to obtain intermediate product A.

[0048] B. Hydrophobic material loaded on the surface of the modified adsorbent: 1g of intermediate product A, 1g of cyanuric chloride and 1.5g of p-terphenyl were dissolved in 10mL of chloroform. 3.3g of AlCl3 was added at room temperature and stirred at 80℃ for 6h. The mixture was filtered with methanol, washed three times, and then purified by Soxhlet extraction with methanol for 24h. After vacuum drying at 80℃ for 12h, the final product B was obtained, which was denoted as modified adsorbent 1.

[0049] The adsorption capacity of modified adsorbent 1 can be calculated using the following formula:

[0050]

[0051] Where V is the adsorption breakthrough capacity (mL / g), F is the gas flow rate (mL / min), t is the adsorption time (min), c is the concentration of hexafluoroethane (%), and m is the mass of adsorbent used (g).

[0052] During the capture process, the concentration of hexafluoroethane in the effluent industrial exhaust gas was detected in real time using online mass spectrometry, and the adsorption breakthrough curve of hexafluoroethane was obtained, as shown in [reference needed]. Figure 1 As shown, the hexafluoroethane adsorption breakthrough capacity of modified adsorbent 1 was calculated to be 45 mL / g.

[0053] Preparation Example 2

[0054] The preparation of Example 2 was performed in the same manner as that of Example 1, except that the unsaturated carboxylic acid ligand was maleic acid. All other operations remained the same, and modified adsorbent 2 was obtained.

[0055] Preparation Example 3

[0056] The preparation of Example 3 was performed in the same manner as that of Example 1, except that the unsaturated carboxylic acid ligand was methylcanonicalic acid. All other operations remained unchanged, and the modified adsorbent 3 was obtained.

[0057] Preparation Example 4

[0058] The procedure for preparation example 4 is the same as that for preparation example 1, except that the unsaturated carboxylic acid ligand is 2-aminofumaric acid. All other procedures remain unchanged, and modified adsorbent 4 is obtained.

[0059] Example 1

[0060] Modified adsorbent 1 was compressed into tablets and sieved to obtain an adsorbent with a mesh size of 16-25. 0.5 g of the adsorbent was filled into the middle of a stainless steel tube with an inner diameter of 6 mm and a length of 400 mm. The adsorption temperature was 25℃, and the adsorbent was activated at 120℃ and -0.1 MPa for 12 h. After the adsorbent bed temperature dropped to 25℃, it was activated at atmospheric pressure for 1800 h. -1Industrial exhaust gas, consisting of 1.6% hexafluoroethane, 0.3% carbon tetrafluoride, 0.7% trifluoromethane, 0.6% difluoromethane, 1.4% water vapor, and 95.4% nitrogen, was introduced from the top of the fixed-bed trap at a space velocity of 1. After adsorption for 10 minutes, the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was analyzed by online mass spectrometry. The capture rate of modified adsorbent 1 on various gases in the inflowing industrial exhaust gas could be calculated.

[0061] Detection and calculation showed that the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was 800-850 ppm, with a capture rate of 99.51% for hexafluoroethane, 86.67% for carbon tetrafluoride, 96.71% for trifluoromethane, 98.33% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0062] Example 2

[0063] The operation of Example 2 is the same as that of Example 1, except that the adsorption temperature is 15°C, and other operations remain unchanged.

[0064] Detection and calculation showed that the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was 700-750 ppm, with a capture rate of 99.69% for hexafluoroethane, 88.33% for carbon tetrafluoride, 96.79% for trifluoromethane, 98.34% for difluoromethane, 0.018% for water vapor, and 1.69% for nitrogen.

[0065] Example 3

[0066] The operation of Example 3 is the same as that of Example 1, except that the adsorption temperature is 35°C, and other operations remain unchanged.

[0067] Detection and calculation showed that the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was 950-1000 ppm, with a capture rate of 99.36% for hexafluoroethane, 86.41% for carbon tetrafluoride, 95.09% for trifluoromethane, 97.64% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0068] Example 4

[0069] The operation of Example 4 is the same as that of Example 1, except that the airspeed is 1000 h. -1 Other operations remain unchanged.

[0070] Detection and calculation showed that the fluorinated greenhouse gas content in the outflowing industrial exhaust gas was 200-250 ppm, with a capture rate of 99.81% for hexafluoroethane, 97.06% for carbon tetrafluoride, 99.02% for trifluoromethane, 99.04% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0071] Example 5

[0072] The operation of Example 5 is the same as that of Example 1, except that the airspeed is 2000 h. -1 Other operations remain unchanged.

[0073] Detection and calculation showed that the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was 950-1000 ppm, with a capture rate of 99.45% for hexafluoroethane, 84.46% for carbon tetrafluoride, 95.77% for trifluoromethane, 97.95% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0074] Example 6

[0075] The operation of Example 6 is the same as that of Example 1, except that the composition of the industrial exhaust gas is 9.6% hexafluoroethane, 0.3% carbon tetrafluoride, 0.7% trifluoromethane, 0.6% difluoromethane, 1.4% water vapor, and 87.4% nitrogen. All other operations remain unchanged.

[0076] Detection and calculation showed that the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was 950-1000 ppm, with a capture rate of 98.12% for hexafluoroethane, 86.57% for carbon tetrafluoride, 97.86% for trifluoromethane, 98.22% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0077] Example 7

[0078] The operation of Example 7 is the same as that of Example 1, except that the composition of the industrial exhaust gas is 1.6% hexafluoroethane, 0.3% carbon tetrafluoride, 0.7% trifluoromethane, 0.6% difluoromethane, 5.4% water vapor, and 91.4% nitrogen. All other operations remain unchanged.

[0079] Detection and calculation showed that the fluorinated greenhouse gas content in the outflowing industrial exhaust gas was 800-850 ppm, with a capture rate of 99.51% for hexafluoroethane, 86.67% for carbon tetrafluoride, 96.71% for trifluoromethane, 98.33% for difluoromethane, 0.021% for water vapor, and 1.55% for nitrogen.

[0080] Example 8

[0081] The operation of Example 8 is the same as that of Example 1, except that the adsorbent material used is modified adsorbent 2, and the other operations remain unchanged.

[0082] Detection and calculation showed that the fluorinated greenhouse gas content in the outflowing industrial exhaust gas was 850-900 ppm, with a capture rate of 97.81% for hexafluoroethane, 90.01% for carbon tetrafluoride, 98.57% for trifluoromethane, 97.52% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0083] Example 9

[0084] The operation of Example 9 is the same as that of Example 1, except that the adsorbent material used is modified adsorbent 3, and the other operations remain unchanged.

[0085] Detection and calculation showed that the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was 750-800 ppm, with a capture rate of 99.06% for hexafluoroethane, 88.44% for carbon tetrafluoride, 97.43% for trifluoromethane, 98.06% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0086] Example 10

[0087] The operation of Example 10 is the same as that of Example 1, except that the adsorbent material used is modified adsorbent 4, and the other operations remain unchanged.

[0088] Detection and calculation showed that the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was 950-1000 ppm, with a capture rate of 98.31% for hexafluoroethane, 89.05% for carbon tetrafluoride, 96.97% for trifluoromethane, 96.93% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0089] Example 11

[0090] The operation of Example 11 is the same as that of Example 1, except that the analysis is performed 5 minutes after adsorption, and all other operations remain the same.

[0091] Detection and calculation showed that the content of fluorinated greenhouse gases in the outflowing industrial exhaust gas was 5-10 ppm, with a capture rate of 99.999% for hexafluoroethane, 99.83% for carbon tetrafluoride, 99.96% for trifluoromethane, 99.98% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0092] Example 12

[0093] The operation of Example 12 is the same as that of Example 1, except that: the adsorbent after adsorption saturation in Example 1 is regenerated and adsorbed a second time. The regeneration conditions are: regeneration temperature 120℃, regeneration pressure -0.1Mpa, regeneration time 1h, and other conditions remain unchanged.

[0094] Detection and calculation showed that the fluorinated greenhouse gas content in the outflowing industrial exhaust gas was 800-850 ppm, with a capture rate of 99.50% for hexafluoroethane, 86.62% for carbon tetrafluoride, 96.71% for trifluoromethane, 98.31% for difluoromethane, 0.017% for water vapor, and 1.55% for nitrogen.

[0095] Comparative Example 1

[0096] The operation of Comparative Example 1 is the same as that of Example 1, except that the adsorbent material used is commercial ZSM-5 molecular sieve, and other operations remain unchanged.

[0097] Detection and calculation showed that the fluorinated greenhouse gas content in the outflowing industrial exhaust gas was 13,800–14,000 ppm, with a capture rate of 79.87% for hexafluoroethane, 24.89% for carbon tetrafluoride, 34.78% for trifluoromethane, 36.44% for difluoromethane, 0.52% for water vapor, and 6.9% for nitrogen.

[0098] Comparative Example 2

[0099] The operation of Comparative Example 2 is the same as that of Example 1, except that the adsorbent used is the commercial MIL-53(Al) metal-organic framework material, and all other operations remain unchanged.

[0100] Detection and calculation showed that the fluorinated greenhouse gas content in the outflowing industrial exhaust gas was 18,400–18,500 ppm, with a capture rate of 57.38% for hexafluoroethane, 17.8% for carbon tetrafluoride, 30.97% for trifluoromethane, 27.67% for difluoromethane, 0.38% for water vapor, and 6.7% for nitrogen.

[0101] Comparative Example 3

[0102] The operation of Comparative Example 3 is the same as that of Example 1, except that the adsorption material used is commercial activated carbon, and all other operations remain unchanged.

[0103] Detection and calculation showed that the fluorinated greenhouse gas content in the outflowing industrial exhaust gas was 17,300–17,500 ppm, with a capture rate of 54.73% for hexafluoroethane, 23.46% for carbon tetrafluoride, 40.45% for trifluoromethane, 39.39% for difluoromethane, 0.13% for water vapor, and 4.3% for nitrogen.

[0104] As can be seen from Examples 1 to 12, the modified adsorbent described in this invention can achieve efficient capture of fluorine-containing greenhouse gases, especially hexafluoroethane, at room temperature and pressure. The modified adsorbent exhibits strong hydrophobicity, enabling efficient adsorption of fluorine-containing greenhouse gases even in industrial exhaust gases containing 5.4% water vapor. This significantly reduces the competitive adsorption selectivity of water vapor and effectively improves the adsorption capacity of fluorine-containing greenhouse gases.

[0105] Comparative Examples 1 to 3 tested the adsorption performance of commercial ZSM-5 molecular sieve samples, commercial MIL-53(Al) samples, and commercial activated carbon samples for fluorine-containing greenhouse gases under the above test conditions. The results showed that the above materials had poor adsorption effects on fluorine-containing greenhouse gases, and the concentration of fluorine-containing greenhouse gases in the gas after adsorption was greater than 1000 ppm.

Claims

1. A method for treating industrial exhaust gas, characterized in that: 100-3000h -1 Industrial exhaust gas containing fluorinated greenhouse gases, including at least hexafluoroethane, is introduced at air velocity into a trap containing a modified adsorbent. The modified adsorbent adsorbs the fluorinated greenhouse gases in the incoming industrial exhaust gas at an adsorption temperature of 5–80°C. Adsorption stops when the concentration of hexafluoroethane in the outgoing industrial exhaust gas drops to 0.1–1000 ppm. The modified adsorbent is a metal-organic framework material with a surface-loaded hydrophobic material, wherein the hydrophobic material is a porous aromatic framework material constructed from aluminum ions and unsaturated dicarboxylic acid ligands. The preparation method of the modified adsorbent specifically includes the following steps: A. Preparation of metal-organic framework materials: Aluminum salt, unsaturated dicarboxylic acid ligand, and aprotic polar solvent are added to a reaction vessel at a molar ratio of 1:(1-5):(20-100) and mixed evenly to form a suspension; 0.05-0.35 mol of organic acid is added to the suspension, and the suspension is heated to 110-180°C and stirred for 24-96 h; intermediate product A is obtained through post-treatment, wherein intermediate product A is a metal-organic framework material constructed by aluminum ions and unsaturated dicarboxylic acid ligand; B. Hydrophobic material loaded on the surface of the modified adsorbent: intermediate product A, aluminum salt, nitrogen-containing organic matter and polycyclic aromatic hydrocarbon are dissolved in 5-50 mL of organic solvent at a mass ratio of 1:(2-10):(1-5):(1-5), mixed evenly, filtered, washed, purified and dried to obtain final product B, wherein the final product B is the modified adsorbent. The aluminum salt is selected from at least one of aluminum chloride, aluminum sulfate, aluminum nitrate, and aluminum silicate; the nitrogen-containing organic compound is selected from at least one of melamine, cyanuric chloride, urea, and biuret; the polycyclic aromatic hydrocarbon is selected from at least one of biphenyl, p-terphenyl, biphenylcarboxyl, and dimethyl biphenylcarboxylate; the unsaturated dicarboxylic acid ligand is selected from... , and At least one of the following, R is selected from at least one of H, OH, CH3, NO2, NH2, F, Cl, Br or I.

2. The processing method according to claim 1, characterized in that: The fluorinated greenhouse gases also include at least one of CF4, SF6, C3F8, CHF3, CH2F2, C4F6, C4F8, and NF3.

3. The processing method according to claim 1, characterized in that: The industrial exhaust gas also includes at least one of N2, NH3, H2, Ar, O2, SiH4, CO, CO2, HBr, Cl2, N2O, and H2O.

4. The processing method according to claim 1, characterized in that: The concentration of fluorinated greenhouse gas in the industrial exhaust gas is 0.1% to 10%; when the concentration of fluorinated greenhouse gas is greater than 10%, it can be diluted with an inert gas.

5. The processing method according to claim 1, characterized in that: The concentration of water vapor in the industrial exhaust gas is 0-10%; when the concentration of water vapor is greater than 10%, it can be dried.

6. The processing method according to claim 1, characterized in that: The adsorption temperature is 20–30℃, the adsorption pressure is 0.05–0.15 MPa, and the space velocity is 1000–2000 h⁻¹. -1 .

7. The processing method according to claim 1, characterized in that: The hydrophobic material is a porous aromatic framework material of 0.1 wt.% to 30 wt.% and has a thickness of 200 to 1000 nm.

8. The processing method according to claim 1, characterized in that: The aprotic polar solvent is selected from at least one of acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, and 1,3-dimethyl-2-imidazolinone; the organic acid is selected from at least one of formic acid, acetic acid, propionic acid, oxalic acid, and benzoic acid; and the organic solvent is selected from at least one of methanol, ethanol, propanol, acetone, and chloroform.

9. The processing method according to claim 1, characterized in that: The modified adsorbent is used in a 10-100 mesh form and undergoes vacuum activation treatment before application, including the following steps: activation temperature of 80-150℃, activation pressure of -0.01--0.1 MPa, activation heating rate of 2-10℃ / min, and activation time of 5-20h.

10. The processing method according to claim 1, characterized in that: The modified adsorbent can be recycled after regeneration treatment, which includes the following steps: regeneration temperature of 80 to 150°C, regeneration pressure of -0.01 to -0.1 MPa, and regeneration time of 0.5 to 3 hours.

Images