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CN-121988123-A - Treatment method of fluorine-containing waste gas

CN121988123ACN 121988123 ACN121988123 ACN 121988123ACN-121988123-A

Abstract

The invention discloses a treatment method of fluorine-containing waste gas, which comprises the steps of introducing fluorine-containing waste gas containing fluorine-containing gas into an absorber with a modified activated carbon adsorbent at a space velocity of 50-5000 h ‑1 , wherein the pressure of the absorber is 0.05-0.5 MPa, the temperature of an adsorbent bed is 10-120 ℃, the fluorine-containing gas comprises hexafluoroethane, nano zero-valent metal and a hydrophobic material are loaded on the surface of the modified activated carbon adsorbent, and the nano zero-valent metal is at least one of Fe, co and Mn. The treatment method disclosed by the invention is simple in process and low in investment cost, and can be used for efficiently enriching the fluorine-containing gas in the fluorine-containing waste gas and reducing the emission of greenhouse gases.

Inventors

  • XIAO HAO
  • ZHU JIADONG
  • YANG MINGSHAN
  • DU XIAOBIN
  • WU JIANGPING

Assignees

  • 浙江省化工研究院有限公司
  • 中化蓝天集团有限公司

Dates

Publication Date
20260508
Application Date
20241105

Claims (10)

  1. 1. A treatment method of fluorine-containing waste gas is characterized by comprising the following steps: Introducing fluorine-containing waste gas containing fluorine-containing gas into an absorber containing the modified activated carbon adsorbent at a space velocity of 50-5000 h -1 , wherein the pressure of the absorber is 0.05-0.5 MPa, the temperature of an adsorbent bed is 10-120 ℃, the fluorine-containing gas comprises hexafluoroethane, The modified activated carbon adsorbent is loaded with nano zero-valent metal and hydrophobic material on the surface, wherein the nano zero-valent metal is selected from at least one of Fe, co and Mn.
  2. 2. The method for treating a fluorine-containing offgas according to claim 1, wherein the fluorine-containing gas further includes at least one kind selected from CF 4 、HF、CH 2 F 2 、CHF 3 、C 2 H 2 F 4 、C 2 HF 5 、C 3 F 6 、C 3 F 8 、C 4 F 6 、C 4 F 8 、C 4 F 10 .
  3. 3. The method for treating a fluorine-containing offgas according to claim 1, characterized in that the fluorine-containing offgas further includes at least one kind selected from N 2 、O 2 、CO 2 、CO、H 2 O、SO 2 、Cl 2 、N 2 O、SiH 4 、PH 3 、AsH 3 、B 2 H 6 .
  4. 4. The method for treating a fluorine-containing waste gas according to claim 1, wherein the concentration of the fluorine-containing gas in the fluorine-containing waste gas is 0.0001 to 20%.
  5. 5. The method for treating a fluorine-containing waste gas according to claim 1, wherein the concentration of water vapor in the fluorine-containing waste gas is 0 to 20%.
  6. 6. The method for treating a fluorine-containing waste gas according to claim 1, wherein the temperature of the adsorbent bed is 15-30 ℃, the pressure of the adsorber is 0.2-0.4 MPa, and the space velocity is 500-1500 h -1 .
  7. 7. The method for treating fluorine-containing waste gas according to claim 1, wherein the content of the nano zero-valent metal is 0.1-10wt.% of the total amount of the modified activated carbon adsorbent, the hydrophobic material is a silane compound, and the content of the hydrophobic material is 0.1-20wt.% of the total amount of the modified activated carbon adsorbent.
  8. 8. The method for treating a fluorine-containing waste gas according to claim 1, wherein the concentration of the fluorine-containing gas after the adsorption treatment is <1ppm.
  9. 9. The method for treating a fluorine-containing exhaust gas according to claim 1, wherein the method for producing the modified activated carbon adsorbent comprises the steps of: A. Preparing an active carbon material, namely preparing 1-50wt.% solution by using a saccharide organic compound, transferring the solution into a high-pressure reaction kettle, carrying out hydrothermal carbonization for 10-36 hours at 160-240 ℃, washing a solid product obtained after the hydrothermal carbonization by using an alcohol solvent, filtering the solid product to obtain hydrothermal carbon, uniformly mixing the hydrothermal carbon and an inorganic base in a mass ratio of 1:0.5-1:5, heating the mixture to 500-900 ℃ in a nitrogen atmosphere for roasting at a temperature rising rate of 2-10 ℃ for 1-10 hours at a nitrogen flow rate of 0.1-1L/min, washing the roasted solid product by using 1mol/L of inorganic acid and deionized water, and drying the solid product at 60-150 ℃ for 5-30 hours to obtain an intermediate product A; B. The method comprises the steps of loading nano zero-valent metal on the surface of a carbon material, namely placing an intermediate product A in a metal salt solution with the concentration of 0.5-2 mol/L, stirring for 1-10 h, filtering, drying at 60-150 ℃ for 5-30 h, heating the dried product to 300-900 ℃ in a nitrogen atmosphere for pyrolysis, wherein the pyrolysis time is 0.5-5 h, the heating rate is 2-10 ℃/min, and the pyrolyzed product is recorded as an intermediate product B; C. And loading a hydrophobic material on the surface of the carbon material, namely mixing an intermediate product B and a silane compound in a mass ratio of 1:0.1-1:10, dispersing in an alcohol solvent, stirring for 0.5-5 h at 25-95 ℃, washing with deionized water, filtering, and vacuum drying the filtered product at 25-150 ℃ for 12-36 h to obtain a final product C, namely the modified activated carbon adsorbent.
  10. 10. The method for treating fluorine-containing waste gas according to claim 9, wherein the sugar organic compound is at least one selected from glucose, sucrose, fructose and polydextrose, the alcohol solvent is at least one selected from methanol, ethanol, ethylene glycol, isopropanol, n-butanol and n-hexanol, the inorganic base is at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate, the inorganic acid is at least one selected from nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid, the metal salt is at least one selected from ferric nitrate, ferric chloride, ferric acetate, cobalt nitrate, cobalt chloride, cobalt acetate, manganese nitrate, manganese chloride and manganese acetate, and the silane compound is at least one selected from hexadecyltrimethoxysilane, dodecyltriethoxysilane, vinyltriethoxysilane, trimethylchlorosilane, octadecyltrichlorosilane and trialkoxysilane.

Description

Treatment method of fluorine-containing waste gas Technical Field The invention relates to the technical field of greenhouse gas emission reduction processes, in particular to a treatment method of fluorine-containing waste gas. Background Most of fluorine-containing gases in the fluorine-containing waste gas discharged in the metal smelting process are fluorine-containing greenhouse gases. Fluorine-containing greenhouse gases are known as super greenhouse gases, including Hydrofluorocarbons (HFCs), sulfur hexafluoride (SF 6), nitrogen trifluoride (NF 3), and Perfluorocarbons (PFCs), which contribute significantly to global warming, with global warming potentials far exceeding CO 2 by thousands or even tens of thousands of times. Fluorine-containing greenhouse gases are strictly regulated by the united states climate change framework convention, and HFCs therein are additionally subject to particular concerns and limitations by the montreal protocol and its basic california amendments. Fluorine-containing greenhouse gases are almost entirely synthesized by hand, and their main emissions are wide, covering a number of industrial fields including the production and use of Ozone Depleting Substances (ODS) alternatives, the fluorination industry, such as byproducts generated in the production of HCFC-22 and other chemicals, the electronics industry, such as integrated circuit, flat panel display and photovoltaic panel manufacturing processes, the power industry, such as the manufacturing and operating stages of electrical equipment, and the metal smelting industry, such as aluminum and magnesium smelting processes. Among the above emission sources, most of the fluorine-containing exhaust gases discharged in the production process of electrolytic aluminum are fluorine-containing greenhouse gases such as CF 4、C2F6, which are harmful to the global atmosphere and require recovery treatment. The GWP 100 value of CF 4 is 7390 and the GWP 100 value of C 2F6 is 12200 are under the key regulations of the Kyoto protocol. In recent years, various policies of governments and international society are in charge of controlling fluorine-containing greenhouse gases, and proposals for comprehensively restricting the production, delivery and use of PFAS (more than 1 ten thousand substances) in Europe are submitted to ECHA by five European countries (Denmark, germany, netherlands, norway and Sweden) in 2023, and the regulation and control of European carbon boundary Conditions (CBAM) in 2023 are formally issued on European official gazette in 2026, which prescribes that carbon tax is paid to fluorine-containing greenhouse gases discharged during the production and processing of aluminum products gradually after 1 month 1. The strength of controlling greenhouse gases is enhanced, and the electrolytic aluminum industry becomes a second industry which is brought into the mandatory carbon market. For aluminum smelting enterprises, carbon tax is paid for fluorine-containing greenhouse gases such as CF 4、C2F6 and the like discharged from electrolytic aluminum production, and from the viewpoints of economic benefit and social influence, the discharge of the fluorine-containing greenhouse gases is required to be reduced, and the fluorine-containing greenhouse gases are required to be recovered. The electrolytic aluminum waste gas has the characteristics of complex composition, low concentration and high air quantity, the existing direct combustion method, catalytic decomposition method and the like are suitable for treating the waste gas with high concentration and low air quantity, and the problems of high energy consumption and high cost exist in treating the waste gas with low concentration and high air quantity, so that the waste gas needs to be adsorbed and concentrated, and the fluorine-containing gas in the waste gas is concentrated and then treated, thereby saving the energy consumption and reducing the cost. There are few reports in the prior art about the disposal of fluorine-containing gases. Chinese patent CN107899388a discloses a method for treating waste gas containing fluorine, which is to adsorb and degrade industrial waste gas containing HF and SiF 4 through steps of waste gas filtration, mixing atomized solution, secondary filtration, permeable reactive barrier reaction, post-treatment, etc., the method has higher treatment efficiency, but has complex process, high investment cost and serious equipment corrosion. Chinese patent CN102886197a discloses a method for treating waste gas containing fluorine, in which the flue gas containing water and fog enters an electric demister from the upper part of a tower for absorbing filler by alkaline method, the gas is ionized into positive and negative ions, charged acid fog particles move onto the inner wall of a precipitation electrode, and then fall into a waste liquid collecting tank of the electric demister along the wall. The method can ensure that the fluoride reaches the s