Etching-induced defect fe se-eriochite composite material, and preparation method and application thereof

Abstract

The application provides an etching-induced defect FeSe-sepiolite composite material and a preparation method and application thereof, and belongs to the technical field of industrial flue gas purification. A selenium source, a reducing agent, an iron source and a surfactant are mixed, etched FeSe is prepared through a hydrothermal reaction-acid etching treatment, and then is mechanically ball milled with sepiolite to obtain the etching-induced defect FeSe-sepiolite composite material. In the composite material, FeSe serves as an active substance, can inhibit the organicization and re-release of mercury from the root due to the antagonism between Hg and Se, and reduces the risk of secondary pollution; sepiolite has a natural fibrous structure, can provide an efficient mass transfer channel, reduces the diffusion resistance of Hg 0 , and simultaneously strengthens the interface bonding between FeSe and sepiolite by means of the shear force generated by mechanical ball milling, so that the structural stability of the adsorbent and the resistance to flue gas scouring are improved.

Description

Technical Field

[0001] This invention belongs to the field of industrial flue gas purification technology, and particularly relates to an etching-induced defect FeSe-sepiolite composite material, its preparation method and application. Background Technology

[0002] Waste-to-energy incineration, as a mainstream method for the harmless and resource-based treatment of waste, produces mercury-containing flue gas during operation, including gaseous elemental mercury (Hg). 0 Gaseous mercury is characterized by high volatility, high toxicity, and poor water solubility, making it prone to migration and accumulation in the environment, posing a serious threat to the ecological environment and human health. Currently, the removal of gaseous mercury from waste-to-energy plants has become a research hotspot in the field of environmental protection.

[0003] Existing adsorbents for gaseous mercury removal mainly include activated carbon, metal oxides, and metal selenides. Activated carbon adsorbents are widely studied due to their low cost, but they suffer from problems such as low adsorption capacity, poor selectivity, and weak resistance to acidic gas interference—the high HCl content in waste incineration flue gas easily binds to the active sites on the activated carbon surface, leading to a significant decrease in mercury adsorption performance, and the mercury is easily released again after adsorption. Metal selenides, because they can bind with Hg... 0 Strong chemical reactions produce stable HgSe, which has better mercury removal activity and selectivity than activated carbon. However, single FeSe particles are prone to agglomeration, resulting in insufficient exposure of active sites. Furthermore, they have poor binding with the carrier and are easily detached and deactivated under flue gas scouring, which limits their industrial application.

[0004] Sepiolite, a natural fibrous clay mineral, possesses advantages such as large specific surface area, abundant pore structure, low price, and environmental friendliness, making it an ideal adsorbent carrier. In existing technologies, the composite of metal selenides and selenite is mostly achieved through impregnation, which suffers from uneven dispersion of active components and weak interfacial bonding. Therefore, developing a FeSe / selenite composite adsorbent with a simple preparation process, good dispersion of active components, strong resistance to HCl interference, and suitability for the flue gas environment of waste incineration power plants is of significant practical importance. Summary of the Invention

[0005] To address the problems of existing mercury removal adsorbents, such as weak resistance to HCl interference, easy agglomeration of FeSe particles, poor binding between active components and carriers, and insufficient adaptability to the flue gas environment of waste incineration power plants, this invention proposes an etching-induced defect FeSe-sepiolite composite material, its preparation method, and its application, in order to achieve the removal of Hg from HCl-containing flue gas in waste incineration power plants. 0 Highly efficient and stable removal.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing an etching-induced defect FeSe-sepiolite composite material, comprising the following steps: (1) The selenium source, reducing agent, iron source and surfactant are mixed and the etched FeSe is prepared by hydrothermal reaction-acid etching treatment; (2) The etched FeSe obtained in step (1) is mechanically ball-milled with sepiolite to obtain the etching-induced defect FeSe-sepiolite composite material.

[0007] Further, in step (1), the selenium source is selenium powder, sodium selenate, or sodium selenite; the iron source is ferrous sulfate (FeSO4·7H2O), ferrous chloride (FeCl2), or ferrous nitrate (Fe(NO3)2); the reducing agent is hydrazine hydrate; the surfactant is hexadecyltrimethylammonium bromide (CTAB); and the molar ratio of the selenium source to the iron source is 1:1.

[0008] Further, in step (1), the acid etching in the hydrothermal reaction-acid etching process includes internal etching and external etching. The internal etching is to add sulfuric acid (H2SO4) solution to the hydrothermal reaction system, and the external etching is to stir and etch the FeSe obtained by the hydrothermal reaction with sulfuric acid solution.

[0009] Furthermore, the concentration of the sulfuric acid solution is 0.092~0.368 mol / L.

[0010] Furthermore, the hydrothermal reaction temperature is 120~200℃, and the reaction time is 10~24h.

[0011] Furthermore, in step (2), the sepiolite is pre-treated with acid and sieved to a particle size of 100 mesh.

[0012] Further, in step (2), the mass ratio of FeSe to sepiolite is 0.5: (0.25~1.0).

[0013] Further, in step (2), the ball-to-material mass ratio of the mechanical ball mill is 11:1 to 25:1, the rotation speed is 100 to 400 rpm, the running time is 1 to 6 hours, the interval time is 0.5 hours, and the cycle is repeated twice.

[0014] The present invention also provides an etching-induced defect FeSe-sepiolite composite material, which is prepared according to the above preparation method. The composite material includes sepiolite and FeSe loaded on the surface of sepiolite.

[0015] The present invention also provides an application of the above-mentioned etching-induced defect FeSe-sepiolite composite material in mercury removal from flue gas of waste incineration power plants.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides a FeSe-sepiolite composite material, in which FeSe acts as the active substance, and due to the antagonistic effect between Hg and Se, Hg... 0 It can undergo a specific chemical reaction with FeSe to form a stable HgSe complex, the reaction formula is: Hg 0 +FeSe→HgSe+Fe 0 This reaction can inhibit the organication and re-release of mercury at its source, reducing the risk of secondary pollution; sepiolite, with its natural fibrous structure, provides efficient mass transfer channels, reducing Hg. 0 Diffusion resistance is reduced, and the shear force generated by mechanical ball milling strengthens the interfacial bonding between FeSe and sepiolite, thereby improving the structural stability and flue gas erosion resistance of the adsorbent. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The graph shows a comparison of the mercury removal performance of 0.092FeSe, 0.184FeSe, 0.368FeSe in Example 1 and FeSe in Comparative Example 1. Figure 2 The mercury removal performance test results are for the internally etched FeSe (0.092FeSe, 0.184FeSe, 0.368FeSe) obtained in Example 1, the three externally etched FeSe (ex0.092FeSe, ex0.184FeSe, ex0.368FeSe) obtained in Example 2, and the FeSe obtained in Comparative Example 1. Figure 3 The graph shows a comparison of the mercury removal efficiency of the composite materials with different FeSe and sepiolite mass ratios in Examples 3-5 and Comparative Example 2. Figure 4 This is a comparison chart of the mercury removal efficiency of the FeSe-Sep composite material obtained in Example 3 at different temperatures; Figure 5 This is a comparison of the mercury removal efficiency of the FeSe-Sep composite material obtained in Example 3 at different space velocities; Figure 6 This is a comparison chart of the mercury removal efficiency of the FeSe-Sep composite material obtained in Example 3 under mixed flue gas. Figure 7 This is a comparison chart showing the mercury removal efficiency of the composite materials obtained in Comparative Example 3 and Example 3 at different times. Detailed Implementation

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0019] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0020] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0021] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0022] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0023] This invention provides a method for preparing an etching-induced defect FeSe-sepiolite composite material, comprising the following steps: (1) Selenium source, reducing agent, iron source and surfactant are mixed and etched FeSe is prepared by hydrothermal reaction-acid etching treatment; (2) The FeSe obtained in step (1) is mechanically ball-milled with sepiolite to obtain etching-induced defect FeSe-sepiolite composite material (FeSe-Sep composite material).

[0024] This invention utilizes a hydrothermal reaction to induce selenium and iron sources to crystallize directionally under the action of a reducing agent and a surfactant to generate FeSe. Sulfuric acid simultaneously etches defects, increasing the number of active sites. Mechanical ball milling utilizes shearing and impact forces to uniformly load FeSe onto the surface of sepiolite, strengthening interfacial bonding and solving the problem of FeSe agglomeration.

[0025] In step (1) of some embodiments of the present invention, the selenium source is selenium powder (Se 0 Sodium selenate or sodium selenite, preferably Se... 0 The iron source is ferrous sulfate heptahydrate (FeSO4·7H2O), ferrous chloride (FeCl2) or ferrous nitrate (Fe(NO3)2), preferably FeSO4; the reducing agent is hydrazine hydrate; the surfactant is hexadecyltrimethylammonium bromide (CTAB), and the molar ratio of selenium source to iron source is 1:1.

[0026] In step (1) of some embodiments of the present invention, the acid etching in the hydrothermal reaction-acid etching process includes internal etching and external etching. Internal etching is to add sulfuric acid (H2SO4) solution to the hydrothermal reaction system, and external etching is to stir and etch the FeSe obtained by the hydrothermal reaction with sulfuric acid solution. The concentration of sulfuric acid solution is 0.092~0.368mol / L, the reaction temperature of the hydrothermal reaction is 120~200℃, and the reaction time is 10~24h. Preferably, the reaction temperature is 150℃ and the reaction time is 12h.

[0027] In step (2) of some embodiments of the present invention, the sepiolite is pre-treated with acid and sieved to a particle size of 100 mesh. Specifically, the sepiolite is spread flat on a sieve, passed through a 100-mesh sieve for 15 minutes, and left to stand for 5 minutes. 10g of the sieved sepiolite is added to 250mL of 10wt.% HCl (hydrochloric acid) solution and soaked for 12 hours. After that, it is washed until neutral and then placed in an oven at 110℃ to dry for 12 hours for later use.

[0028] In step (2) of some embodiments of the present invention, the mass ratio of FeSe to sepiolite is 0.5: (0.25~1.0).

[0029] In step (2) of some embodiments of the present invention, the ball-to-material mass ratio of the mechanical ball mill is 11:1 to 25:1 (preferably 11:1), the rotation speed is 100 to 400 rpm, the running time is 1 to 6 hours, the interval time is 0.5 hours, and the cycle is repeated twice. Preferably, the rotation speed is 400 rpm, the running time is 1 hour, the interval time is 0.5 hours, and the cycle is repeated twice.

[0030] For example, in this embodiment of the invention, the preparation of etching-induced defect FeSe-sepiolite composite material by internal etching specifically includes the following steps: (1) Weigh 0.01 mol of FeSO4·7H2O (2.7802 g) and 0.3 g of CTAB and add them to 70 mL of H2SO4 solution (concentration 0.092~0.368 mol / L). Stir for 30 min to ensure that the solvent is completely dissolved to obtain mixture 1; then weigh 0.01 mol of Se0 (0.7896) was added to 10 mL of hydrazine hydrate. Nitrogen gas was generated during this process. Stirring was continued for 30 min to obtain mixture 2. Mixture 1 and mixture 2 were mixed and stirred for 5 min. The mixture was then observed for any color change. The mixture was then transferred to a reaction vessel (100 mL) and hydrothermally reacted at 150 °C for 12 h. After the solution cooled naturally, the supernatant in the reaction vessel was poured out. The solid was then washed twice with deionized water and once with ethanol. The tube was then sealed with tin foil and placed in a refrigerator to freeze for more than 1 h. Finally, the tube was freeze-dried, sealed, and passed through a 100-mesh sieve for later use. The etched FeSe was thus prepared. (2) Weigh (0.25~1.0) g of pretreated sepiolite powder and 0.5 g of FeSe obtained in step (1), pour them into a ball mill jar, stir with a spatula to mix them evenly, use a semi-dry method, that is, use 0.5 mL of ethanol solution to wet the mixture, add a certain amount of steel balls (10 mm diameter, 4 g / ball) to the jars according to a ball-to-material mass ratio of 11:1, place the two ball mill jars diagonally in a planetary ball mill, and set the following program: rotation speed of 400 rpm, running time of 6 h, interval time of 0.5 h, cycle twice, and after ball milling is completed, FeSe-sepiolite composite material is obtained.

[0031] When using external etching to prepare etching-induced defect FeSe-sepiolite composite materials, the specific steps include: (1) Weigh 0.01 mol of FeSO4·7H2O (2.7802 g) and 0.3 g of CTAB and add them to 70 mL of deionized water. Stir for 30 min to ensure that the solvent is completely dissolved to obtain mixture 1; then weigh 0.01 mol of Se 0 (0.7896) was added to 10 mL of hydrazine hydrate. Nitrogen gas was generated during this process. Stirring was continued for 30 min to obtain mixture 2. Mixture 1 and mixture 2 were mixed and stirred for 5 min. The mixture was then observed for any color change. The mixture was then transferred to a reaction vessel (100 mL) and hydrothermally reacted at 150 °C for 12 h. After the solution cooled naturally, the supernatant in the reaction vessel was poured out. The solid obtained was the unetched FeSe. 600 mg of the unetched FeSe was then added to 70 mL of H2SO4 solution (concentration of 0.092~0.368 mol / L) and stirred for 12 h. The solid was then washed twice with deionized water and once with ethanol. The tube was then sealed with tin foil and placed in a refrigerator to freeze for more than 1 h. Finally, the tube was freeze-dried, sealed, and passed through a 100-mesh sieve for later use to obtain etched FeSe. (2) is consistent with step (2) of internal etching.

[0032] This invention also provides an etching-induced defect FeSe-sepiolite composite material, which is prepared according to the above preparation method. The composite material includes sepiolite and FeSe loaded on the surface of sepiolite. The mass percentage of sepiolite in the composite material is 33.3%~75%, and the mass percentage of FeSe is 25%~66.7%.

[0033] This invention also provides an application of the above-mentioned etching-induced defect FeSe-sepiolite composite material in mercury removal from flue gas in waste incineration power plants.

[0034] All raw materials used in the embodiments of this invention were purchased commercially.

[0035] The technical solution of the present invention will be further illustrated by the following embodiments.

[0036] Example 1 The preparation of etched FeSe using internal etching specifically includes the following steps: Weigh 0.01 mol of FeSO4·7H2O (2.7802 g) and 0.3 g of CTAB and add them to 70 mL of H2SO4 solution (concentration 0.184 mol / L). Stir for 30 min to ensure complete solvent dissolution, obtaining mixture 1; then weigh 0.01 mol of Se... 0 0.7896 g of hydrazine hydrate was added to 10 mL of hydrazine hydrate. Nitrogen gas was generated during this process. The mixture was stirred for 30 min to obtain mixture 2. Mixture 1 and mixture 2 were mixed and stirred for 5 min. The mixture was then observed for any color change. The mixture was then transferred to a 100 mL reactor and hydrothermally reacted at 150 °C for 12 h. After the solution cooled naturally, the supernatant in the reactor was poured out. The solid was then washed twice with deionized water and once with ethanol. The tube was then sealed with tin foil and frozen in a refrigerator for more than 1 h. Finally, the tube was freeze-dried, sealed, and passed through a 100-mesh sieve for later use. The etched FeSe was prepared and denoted as 0.184FeSe. By changing the concentration of the H2SO4 solution in the above preparation process to 0.092 and 0.368 mol / L, respectively, etched FeSe was obtained, which were denoted as 0.092FeSe and 0.368FeSe.

[0037] Comparative Example 1 Weigh 0.01 mol of FeSO4·7H2O (2.7802 g) and 0.3 g of CTAB and add them to 70 mL of deionized water. Stir for 30 min to ensure complete solvent dissolution, obtaining mixture 1. Then weigh 0.01 mol of Se... 0(0.7896) was added to 10 mL of hydrazine hydrate. Nitrogen gas was generated during this process. Stirring was continued for 30 min to obtain mixture 2. Mixture 1 and mixture 2 were mixed and stirred for 5 min. The mixture was then observed for any color change. The mixture was then transferred to a reaction vessel (100 mL) and hydrothermally reacted at 150 °C for 12 h. After the solution cooled naturally, the supernatant in the reaction vessel was poured out. The solid was then washed twice with deionized water and once with ethanol. The tube was then sealed with tin foil and placed in a refrigerator to freeze for more than 1 h. Finally, the tube was freeze-dried, sealed, and passed through a 100-mesh sieve for later use. Unetched FeSe was thus prepared.

[0038] Performance testing: 50 mg of the FeSe samples prepared in Example 1 (0.092FeSe, 0.184FeSe, and 0.368FeSe) and the FeSe obtained in Comparative Example 1 were weighed out respectively and placed in a simulated fixed-bed reactor. Gaseous elemental mercury was generated through a mercury permeation tube. The concentration of elemental mercury at the reactor inlet and outlet was monitored in real time using a Lumex-915 mercury analyzer. The total gas flow rate was 0.5 L·min. -1 The initial mercury concentration was 280 ng·m -3 The adsorption temperature was 90℃, and the space velocity was set to 5.31 × 10⁻⁶. 5 h -1 The concentration of SO2 was 800 ppm, and the remainder was N2. Mercury removal performance was tested, and the results are as follows: Figure 1 As shown, the adsorption efficiency of unetched FeSe is significantly lower than that of etched 0.092FeSe, 0.184FeSe, and 0.368FeSe. Furthermore, the adsorption efficiency of FeSe decreases significantly over time, while that of 0.092FeSe, 0.184FeSe, and 0.368FeSe remains at the highest value. This indicates that etched 0.092FeSe, 0.184FeSe, and 0.368FeSe have high and stable removal efficiency for mercury.

[0039] Example 2 The preparation of etched FeSe by external etching specifically includes the following steps: Weigh 0.01 mol of FeSO4·7H2O (2.7802 g) and 0.3 g of CTAB and add them to 70 mL of deionized water. Stir for 30 min to ensure complete solvent dissolution, obtaining mixture 1. Then weigh 0.01 mol of Se... 0(0.7896) was added to 10 mL of hydrazine hydrate. Nitrogen gas was generated during this process. Stirring was continued for 30 min to obtain mixture 2. Mixture 1 and mixture 2 were mixed and stirred for 5 min. The color change was observed. The mixture was then transferred to a reaction vessel (100 mL) and hydrothermally reacted at 150 °C for 12 h. After the solution cooled naturally, the supernatant in the reaction vessel was poured out. The solid obtained was unetched FeSe. 600 mg of unetched FeSe was then added to 70 mL of H2SO4 solution (concentration of 0.184 mol / L) and stirred for 12 h. The solid was then washed twice with deionized water and once with ethanol. The tube was then sealed with tin foil and frozen in a refrigerator for more than 1 h. Finally, it was freeze-dried, sealed, and passed through a 100-mesh sieve for later use to obtain etched FeSe, denoted as ex0.184FeSe. By changing the concentration of the H2SO4 solution in the above preparation process to 0.092 and 0.368 mol / L, respectively, etched FeSe was obtained, which were denoted as ex0.092FeSe and ex0.368FeSe.

[0040] Performance Testing: 50 mg of each of the following FeSe samples were weighed: internally etched FeSe (0.092FeSe, 0.184FeSe, 0.368FeSe) obtained in Example 1, externally etched FeSe (ex0.092FeSe, ex0.184FeSe, ex0.368FeSe) obtained in Example 2, and FeSe obtained in Comparative Example 1. Each sample was placed in a simulated fixed-bed reactor. Gaseous elemental mercury was generated through a mercury permeation tube. The concentration of elemental mercury at the reactor inlet and outlet was monitored in real time using a Lumex-915 mercury analyzer. The total gas flow rate was 0.5 L·min. -1 The initial mercury concentration was 280 ng·m -3 The adsorption temperature was 90℃, and the space velocity was set to 5.31 × 10⁻⁶. 5 h -1 The sulfur resistance test included SO2 concentrations of 400, 800, and 1200 ppm, with the remainder being N2. Mercury removal performance was then tested, and the results are as follows: Figure 2 As shown, it can be seen that the removal efficiency of mercury by ex0.092FeSe, ex0.184FeSe, ex0.368FeSe is not significantly different from that of 0.092FeSe, 0.184FeSe, and 0.368FeSe, and is significantly better than that of unetched FeSe. Moreover, the adsorption effect does not decrease significantly with the increase of SO2 gas flow rate, indicating that both external and internal etching have good anti-interference performance.

[0041] Example 3 A method for preparing an etching-induced defect FeSe-Sep composite material specifically includes the following steps: (1) Spread sepiolite flat in a sieve, pass it through a 100-mesh sieve for 15 minutes, let it stand for 5 minutes, take 10g of the sieved sepiolite and add it to 250mL of 10wt.% HCl (hydrochloric acid) solution, soak it for 12 hours, then wash it until neutral, and then put it in an oven at 110℃ to dry for 12 hours to obtain pretreated sepiolite; (2) Preparation of 0.184FeSe, the preparation method is the same as in Example 1; (3) Weigh 0.5g of sepiolite powder pretreated in step (1) and 0.5g of FeSe obtained in step (2), pour them into a ball mill jar, stir with a spatula to mix them evenly, use a semi-dry method, that is, use 0.5mL of ethanol solution to wet the mixture, add a certain amount of steel balls (10mm diameter, 4g / ball) to the jar according to the ball-to-material mass ratio of 11:1, place the two ball mill jars diagonally in the planetary ball mill, and set the following program: rotation speed of 400 rpm, running time of 6h, interval time of 0.5h, and cycle twice; (4) After ball milling, the product is taken out with a spatula and poured into a petri dish. It is then sealed with tin foil and placed in a refrigerator to freeze for 1 hour. After freezing, it is taken out, small holes are punched in the tin foil, and then it is transferred to a vacuum freeze dryer to freeze for 6 hours. After the above steps are completed, it is taken out and ground into a fine powder of 100 mesh with an agate mortar and pestle. Finally, FeSe-Sep composite material is obtained, in which FeSe accounts for 50% of the mass of the composite material.

[0042] Example 4 Same as Example 3, except that the amount of pretreated sepiolite powder was changed to 0.25g, and the other steps were kept the same as in Example 3 to obtain FeSe-Sep composite material, wherein the mass ratio of FeSe in the composite material was 66.7%.

[0043] Example 5 Same as Example 3, except that the amount of pretreated sepiolite powder was changed to 1.0g, and the other steps were kept the same as in Example 3 to obtain FeSe-Sep composite material, wherein the mass ratio of FeSe in the composite material was 33.3%.

[0044] Comparative Example 2 Same as Example 3, except that the amount of pretreated sepiolite powder was changed to 1.5g, and the other steps were kept the same as in Example 3 to obtain FeSe-Sep composite material, wherein the mass ratio of FeSe in the composite material was 25%.

[0045] Test Example 1 50 mg of the composite materials from Example 3 (1:1, i.e., the mass ratio of FeSe to sepiolite, the same below), Example 4 (2:1), Example 5 (1:2), and Comparative Example 2 (1:3) were weighed and placed in a simulated fixed-bed reactor. Gaseous elemental mercury was generated through a mercury permeation tube, and the concentration of elemental mercury at the reactor inlet and outlet was monitored in real time using a Lumex-915 mercury analyzer. Real flue gas conditions were simulated by controlling the flow rate and proportion of various gas components, with a total gas flow rate of 0.5 L·min. -1 The initial mercury concentration was 280 ng·m -3 The adsorption temperature was 90℃, and the space velocity was set to 5.31 × 10⁻⁶. 5 h -1 The result is as follows Figure 3 It can be seen that under pure N2, the mercury removal performance of composite materials with different proportions was tested. As the FeSe ratio gradually increased from 1:3 to 1:1, the mercury removal efficiency of the composite material increased from 62.0% to 99.2%. This is attributed to the porous structure of sepiolite, which can fix FeSe and prevent its loss, while also increasing the contact area with the reactants, thus improving the mercury removal efficiency. As the FeSe ratio continued to increase from 1:1 to 2:1, the mercury removal efficiency of the composite material decreased by 2.5%. This is mainly due to the agglomeration of FeSe on the sepiolite surface. Based on performance and economy, the 1:1 ratio material exhibits the best performance.

[0046] Test Example 2 50 mg of the FeSe-Sep composite material obtained in Example 3 was weighed and subjected to simulated adsorption temperature testing under pure nitrogen conditions. The simulation apparatus used was the same as that used in Example 1, and the total gas flow rate was 0.5 L·min. -1 The initial mercury concentration was 280 ng·m -3 The airspeed was set to 5.31 × 10⁻⁶. 5 h -1 The adsorption temperatures were 30, 90, 150, and 200℃. The adsorption efficiencies at different temperatures are shown below. Figure 4 As shown, the FeSe-Sep composite material obtained in Example 3 exhibits excellent mercury removal performance in the low-temperature range. Under pure N2, the mercury removal efficiency reaches over 99% at 30℃ and 90℃. The mercury removal performance decreases with increasing temperature, likely due to mercury desorption or decomposition of mercury compounds, leading to performance degradation. However, it still maintains a mercury removal efficiency of 95.9% at 200℃, indicating its adaptability over a wide temperature range.

[0047] Test Example 3 50 mg of the FeSe-Sep composite material obtained in Example 3 was weighed and subjected to simulated adsorption temperature testing under pure nitrogen conditions. The simulation apparatus used was the same as that used in Example 1, and the total gas flow rate was 0.5 L·min.-1 The initial mercury concentration was 280 ng·m -3 The adsorption temperature was 90℃, and the space velocity was set to 3.18 × 10⁻⁶. 5 5.31×10 5 7.43×10 5 1.06×10 6 h -1 Adsorption efficiency at different space velocities, such as Figure 5 As shown, under different space velocities, the mercury removal efficiency of the FeSe-Sep composite material obtained in Example 3 rapidly increased from 0 to over 95% within 0-5 minutes, and remained at nearly 100% after 5 minutes, unaffected by airflow velocity. The material exhibits extremely high stability and efficient removal performance, making it well-suited to the operating conditions of power plants. This phenomenon is attributed to two factors: firstly, the pore structure of the carrier sepiolite is Hg... 0 Diffusion provides a low-drag path, even with increased airspeed, Hg 0 It can still quickly reach the active site of FeSe; secondly, the Se active site of FeSe is related to Hg. 0 The chemical reaction kinetics are extremely fast, and Hg can be completed in a short contact time. 0 It achieves efficient capture without relying on long-term diffusion and adsorption processes.

[0048] Test Example 4 50g of the FeSe-Sep composite material obtained in Example 3 was weighed and subjected to a simulated waste-to-energy power plant flue gas test. The simulation apparatus used was the same as that used in Example 1, the simulated flue gas adsorption temperature was 90℃, and the total gas flow rate was 0.5L·min. -1 The initial mercury concentration was 280 ng·m -3 The adsorption temperature was 90℃, and the space velocity was set to 5.31 × 10⁻⁶. 5 h -1 The adsorption efficiency of flue gas under different amounts of NO, SO2, O2, CO2, and HCl is as follows: Figure 6 As shown, the adsorption efficiency is almost unaffected by NO, SO2, and O2 gas doping, but decreases slightly with CO2 and HCl gas doping. However, it can still maintain above 83% under simulated waste incineration power plant flue gas, indicating that the composite material obtained by this invention has good anti-interference ability.

[0049] Comparative Example 3 Same as Example 3, except that 0.184FeSe is replaced with an equal mass of FeS, and the other steps remain unchanged to obtain the FeS-Sep composite material.

[0050] Test Example 5 50 mg of FeS-Sep from Comparative Example 3 and FeSe-Sep composite material obtained from sepiolite pretreated in Example 3 were weighed separately and placed in a simulated fixed-bed reactor. Gaseous elemental mercury was generated through a mercury permeation tube, and the concentration of elemental mercury at the reactor inlet and outlet was monitored in real time using a Lumex-915 mercury analyzer. Real flue gas conditions were simulated by controlling the flow rate and proportion of various gas components, with a total gas flow rate of 0.5 L·min. -1 The initial mercury concentration was 280 ng·m -3 The adsorption temperature was 90℃, and the space velocity was set to 5.31 × 10⁻⁶. 5 h -1 The result is as follows Figure 7 As shown, the mercury adsorption performance of the FeS-Sep composite material is inferior to that of the material in Example 3, and the mercury removal efficiency decreases over time, falling below 13% at the 30th minute. It can be seen that the mercury removal performance is significantly lower than that of FeSe-Sep. This is because the binding affinity between mercury and selenium is much stronger than that between mercury and sulfur. Furthermore, the solubility product of HgSe is much lower than that of HgS, resulting in higher thermodynamic stability and enabling the removal of mercury. 0 Irreversible chemical fixation prevents secondary release of mercury from the source.

[0051] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an etching-induced defect FeSe-sepiolite composite material, characterized in that, Includes the following steps: (1) The selenium source, reducing agent, iron source and surfactant are mixed and the etched FeSe is prepared by hydrothermal reaction-acid etching treatment; (2) The FeSe etched in step (1) is mechanically ball-milled with sepiolite to obtain the etching-induced defect FeSe-sepiolite composite material.

2. The method for preparing the etching-induced defect FeSe-sepiolite composite material according to claim 1, characterized in that, In step (1), the selenium source is selenium powder, sodium selenate, or sodium selenite; the iron source is ferrous sulfate, ferrous chloride, or ferrous nitrate; the reducing agent is hydrazine hydrate; the surfactant is hexadecyltrimethylammonium bromide; and the molar ratio of the selenium source to the iron source is 1:

1.

3. The method for preparing the etching-induced defect FeSe-sepiolite composite material according to claim 1, characterized in that, In step (1), the acid etching in the hydrothermal reaction-acid etching process includes internal etching and external etching. The internal etching is to add sulfuric acid solution to the hydrothermal reaction system, and the external etching is to stir and etch the FeSe obtained by the hydrothermal reaction with sulfuric acid solution.

4. The method for preparing the etching-induced defect FeSe-sepiolite composite material according to claim 3, characterized in that, The concentration of the sulfuric acid solution is 0.092~0.368 mol / L.

5. The method for preparing the etching-induced defect FeSe-sepiolite composite material according to claim 3, characterized in that, The hydrothermal reaction temperature is 120~200℃, and the reaction time is 10~24h.

6. The method for preparing the etching-induced defect FeSe-sepiolite composite material according to claim 1, characterized in that, In step (2), the mass ratio of FeSe to sepiolite is 0.5: (0.25~1.0).

7. The method for preparing the etching-induced defect FeSe-sepiolite composite material according to claim 1, characterized in that, In step (2), the sepiolite is pre-treated with acid and sieved, with a particle size of 100 mesh.

8. The method for preparing the etching-induced defect FeSe-sepiolite composite material according to claim 1, characterized in that, In step (2), the ball-to-material mass ratio of the mechanical ball mill is 11:1 to 25:1, the rotation speed is 100 to 400 rpm, the running time is 1 to 6 hours, the interval time is 0.5 hours, and the cycle is repeated twice.

9. An etching-induced defect FeSe-sepiolite composite material, characterized in that, It is prepared according to any one of claims 1 to 8.

10. The application of the etching-induced defect FeSe-sepiolite composite material as described in claim 9 in mercury removal from flue gas in waste incineration power plants.

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