Composite materials, methods of making and using the same

Abstract

The application provides a composite material and a preparation method and application thereof, wherein the composite material comprises sulfide and biomass charcoal, the sulfide is loaded on the biomass charcoal, the sulfide is CoS2 or FeS2, and the mass percentage of the sulfide in the biomass charcoal is 5-35%. In the application, appropriate CoS2 or FeS2 is uniformly loaded on the surface of the biomass charcoal, gaseous elemental mercury can easily contact the active center of the CoS2 or FeS2, and efficient and high-capacity adsorption of the composite material to elemental mercury is realized.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation, specifically relating to a composite material, its preparation method, and its application. Background Technology

[0002] Mercury is a persistent, cumulative, mobile, and highly bioaccumulative toxic heavy metal, and has been listed as the only pollutant besides greenhouse gases that has a global impact.

[0003] Mercury-containing flue gas often contains three different forms of mercury, each with varying chemical properties and levels of difficulty in removal. These include particulate mercury (Hg(p)) and oxidized mercury (Hg(g))... 2+ Mercury (Hg) is stable in nature and can be captured in large quantities by existing dust removal equipment, while elemental mercury (Hg) 0 Due to their high inertia and difficulty in capture, they are often directly discharged into the air, posing a threat to the environment.

[0004] To eliminate this threat, based on the characteristics of low flue gas volume in smelting flue gas, a Co9S8 adsorbent suitable for fixed-bed adsorption has been developed.

[0005] However, the adsorbent has a small adsorption capacity. If it is actually used for mercury removal from smelting flue gas, the adsorption box needs to be replaced frequently during use, which increases the operating cost. Summary of the Invention

[0006] To address the technical problem of low adsorption capacity of mercury adsorbents in the aforementioned related technologies, this invention provides a composite material. The composite material is a mesoporous material comprising sulfides and biochar, wherein the sulfides are loaded onto the biochar, and the sulfides are CoS2 or FeS2; the mass percentage of the sulfides in the biochar is 5-35%.

[0007] Furthermore, the sulfide has a mass percentage of 12-20%.

[0008] This invention provides a method for preparing a composite material, comprising the following steps:

[0009] A metal salt is dissolved in a solvent and sonicated for 2–30 minutes to obtain a salt solution. The metal salt includes cobalt salt or iron salt.

[0010] Porous carbon is impregnated in the salt solution and reacted under hydrothermal conditions at 150–220°C for 4–20 h. Solid-liquid separation is then performed to obtain the precursor. The ratio of the amount of porous carbon to the amount of metal salt is 0.25–1.8 g: 0.0015 mol.

[0011] The precursor is mixed with sulfur, and the mixture is heated to the vulcanization temperature at a heating rate of 5-20℃ / min and held for 1-4 hours to obtain a composite material; wherein the ratio of sulfur to metal salt is 0.12-0.36g:0.0015mol, and the vulcanization temperature is 250-500℃.

[0012] Furthermore, the cobalt salt includes cobalt nitrate, cobalt acetate, and / or cobalt chloride, and the iron salt includes ferric nitrate, ferric acetate, and / or ferric chloride.

[0013] Furthermore, the solvent includes deionized water, and the ratio of the amount of metal salt added to the amount of deionized water can be 0.0015 mol: 10-50 ml.

[0014] Furthermore, the step of impregnating the porous carbon in the salt solution includes: adding the porous carbon to the salt solution and stirring at 10-50°C for 2-6 hours.

[0015] Furthermore, before the sulfur is added, the precursor is dried; wherein the drying temperature is 50-100°C and the drying time is 12-24 hours.

[0016] This invention provides an application of the composite material as described above or the composite material prepared by any of the above preparation methods in the treatment of mercury-containing flue gas.

[0017] Further, the method includes the step of: introducing the mercury-containing flue gas into the composite material; wherein the temperature of the mercury-containing flue gas is 25–75°C, and the mercury concentration in the mercury-containing flue gas is 10–500 μg / m³. 3 .

[0018] Furthermore, the mercury-containing flue gas includes one or more of N2, O2, SO2, NO, HCl, and H2O.

[0019] Compared with the prior art, the present invention has at least the following advantages:

[0020] This invention provides a composite material mainly composed of sulfides and biochar. Biochar, as a porous material, has a dense and unobstructed surface with a large specific surface area, providing abundant attachment sites for cobalt disulfide or iron sulfide. With appropriate amounts of cobalt disulfide or iron sulfide uniformly loaded on the biochar surface, gaseous elemental mercury can easily contact the active centers, achieving efficient and high-capacity adsorption of elemental mercury by the composite material.

[0021] In this invention, cobalt disulfide is applied to the structural composition of composite materials. Compared to Co9S8, CoS2 has a higher proportion of Co on its surface. 3+The high content of active sites and active sulfur results in better mercury removal performance. The reaction mechanism involves mercury being removed by Co. 3+ Or S2 2- Oxidation eventually transforms it into HgS. The mesoporous structure of the composite material facilitates the dispersion of active ingredients and helps reduce Hg in the flue gas. 0 The adsorption process involves rapid dispersion and contact with active sites. Loading a metal salt followed by sulfur sulfidation improves the degree of sulfidation compared to traditional thiourea solution sulfidation, resulting in a higher concentration of Co on the composite material surface. 3+ and S2 2- Active site.

[0022] Meanwhile, during the sulfidation of elemental sulfur, the combination of carbon and cobalt sulfide / iron sulfide can promote the S2... 2- The formation of unsaturated sulfur, etc., is for the removal of Hg. 0 The application provides abundant unsaturated sulfur active sites to maintain efficient and stable mercury removal. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 The nitrogen adsorption-desorption isotherm and pore size distribution diagram of CoS2-h prepared in Example 2 of this invention are shown.

[0025] Figure 2 The image shows the XRD diffraction pattern of CoS2-h obtained in Example 2 of this invention.

[0026] Figure 3 This is a SEM image of CoS2-h obtained in Example 2 of the present invention.

[0027] Figure 4 This is an HR-TEM image of CoS2-h obtained in Example 2 of the present invention.

[0028] Figure 5 This is a mapping diagram of CoS2-h obtained in Example 2 of the present invention.

[0029] Figure 6 This is the EDS point scan spectrum of CoS2-h prepared in Example 2 of the present invention.

[0030] Figure 7 The graphs show the mercury removal performance of CoS2-h prepared at different sulfidation temperatures in Examples 1-3 of this invention.

[0031] Figure 8 This is a test graph showing the mercury removal performance of CoS2-h at different mercury-containing flue gas temperatures in Example 4 of the present invention.

[0032] Figure 9 The graph shows the mercury removal performance of CoS2-h under different flue gas composition conditions in Example 5.

[0033] Figure 10 This is a test curve of mercury adsorption capacity under simulated non-ferrous metal smelting flue gas in Example 6 of the present invention (CoS2-h long-term saturated adsorption curve).

[0034] Figure 11 The graphs show the mercury removal performance of the composite material prepared in Example 2 of Comparative Example 1 of this invention and the composite material prepared at different calcination temperatures.

[0035] Figure 12 The graphs show the mercury removal performance of the composite material prepared in Example 2 of Comparative Example 2 of this invention.

[0036] Figure 13 The FeS prepared in Example 7 x XRD pattern of sample / C.

[0037] Figure 14 The FeS prepared in Example 7 of this invention x XRD characteristic peak matching diagram of / C precursor and hematite Fe2O3 (PDF#33-0664).

[0038] Figure 15 FeS prepared in Example 7 of this invention x Raman spectrum of / C.

[0039] Figure 16 FeS prepared in Example 7 of this invention x SEM and EDS images of / C.

[0040] Figure 17 FeS prepared in Example 7 of this invention x -200, FeS x -400 and FeS x Mercury removal performance diagram of -500 under N2.

[0041] Figure 18 FeS was prepared under different adsorption temperature conditions as described in Example 7 of this invention. x Mercury removal performance of -400 under 6% SO2 + 6% O2 environment.

[0042] Figure 19 FeS prepared in Example 7 of this invention xMercury removal efficiency of -400 at 125℃ and 50℃ respectively.

[0043] Figure 20 FeS prepared in Example 7 of this invention x Mercury removal efficiency of -400 under N2 and 6% SO2 + 6% O2 environments.

[0044] Figure 21 FeS prepared in Example 7 of this invention x -400 Mercury removal performance diagram under different flue gas components.

[0045] Figure 22 FeS prepared in Example 7 of this invention x -400 long-term mercury removal performance diagram under 6% SO2 + 6% O2 environment.

[0046] Figure 23 FeS prepared in Example 7 of this invention x -400 and the Used FeS obtained after mercury adsorption x XPS graph of -400.

[0047] Mercury removal efficiency refers to the efficiency of mercury removal; Hg 0 Removal efficiency refers to the efficiency of mercury removal. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0050] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0051] Through extensive research, the inventors discovered that although the Co9S8 adsorbent material produced in the relevant technology has a certain ability to treat smelting flue gas, its adsorption capacity is relatively small.

[0052] To further improve the compatibility of the adsorbent with smelting flue gas, a CoS2 / PC material was prepared using common techniques. This material can adapt to the high sulfur characteristics of smelting flue gas. Its preparation process involves simultaneously adding cobalt nitrate and thiourea to a solution. Sulfidation occurs during the cobalt crystallization process. However, due to incomplete cobalt crystallization and the fact that the sulfur in thiourea is organic sulfur with poor sulfidation activity, the final product exhibits low mercury removal efficiency.

[0053] This invention utilizes cobalt salts to prepare CoS2-h, employing a hydrothermal reaction between a cobalt source and carbon to better disperse cobalt on the carbon surface, forming a precursor. This invention also uses elemental sulfur as a sulfur source; elemental sulfur has a zero valence and stronger oxidizing activity than organic sulfur, thus resulting in a more effective sulfidation. The added benefit is that the product Co of this invention... 3+ and S2 2- It has a higher content of active sites and better mercury removal efficiency.

[0054] This invention also utilizes an iron source and carbon to synthesize unsaturated sulfur-rich FeS2 / porous carbon (i.e., FeS2 / C, hereinafter the same). FeS2 / C is rich in unsaturated sulfur and exhibits good Hg performance at low temperatures. 0 The adsorption activity was improved, enabling the regulation of unsaturated sulfur in sulfur-containing adsorbents.

[0055] Based on the above, the present invention provides a composite material. The mercury adsorbent comprises a sulfide and biochar, wherein the sulfide is loaded on the biochar, and the sulfide is CoS2 or FeS2; the mass percentage of the sulfide in the biochar is 5-35%.

[0056] For example, the mass percentage of the sulfide can be 12-20%.

[0057] The specific surface area, pore volume, and pore size of CoS2-h were tested using an N2 adsorption / desorption method. Figure 1 As shown, the nitrogen adsorption-desorption curve of CoS2-h shows a clear inflection point around P / P0 = 0.1, which represents the adsorption capacity when the micropores are completely filled. Its specific surface area is 625 m² / g. 2 / g, total pore volume is 0.299cm³ 3 / g, with an average pore size of 1.9047nm.

[0058] This invention analyzes the XRD of CoS2-h, referring to... Figure 2The broad diffraction peak near 24° corresponds to amorphous carbon, while multiple diffraction peaks at 27.8°, 32.3°, 36.2°, 39.8°, 46.3°, 54.9°, 60.1°, and 62.7° correspond to the (111), (200), (210), (211), (220), (311), (023), and (321) crystal planes of cubic CoS2. This confirms that the synthesized material is a composite material of CoS2 and carbon.

[0059] This invention further investigated the microstructure and structure of CoS2-h using SEM and HR-TEM. For example... Figure 3 As shown, CoS2-h exhibits a uniform spherical structure with cobalt disulfide uniformly loaded on its surface, without forming agglomerates or stacks.

[0060] HR-TEM images show clear lattice fringes (reference) Figure 4 The interplanar spacing is 0.270 nm, corresponding to the CoS2 phase (200) plane, which is consistent with the XRD results.

[0061] refer to Figure 5 The mapping diagram shows that Co and S elements are evenly distributed on the surface of the carbon support, and the S on the adsorbent surface is significantly more than Co, indicating that the oversulfurization method achieves surface sulfur enrichment.

[0062] Figure 6 The EDS spot scan spectrum showed that the atomic ratio of Co to S was 1:2. This further demonstrates that the present invention synthesized a CoS2 / carbon composite material with a mesoporous structure on a mesoporous carbon substrate through impregnation and sulfur sulfidation.

[0063] CoS2-h for Hg 0 The adsorption capacity is 40–120 mg / g

[0064] FeS2 / C for Hg 0 The adsorption capacity is 40–120 mg / g

[0065] Compared with the prior art, the present invention has at least the following advantages:

[0066] This invention provides a composite material mainly composed of CoS2 or FeS2 and biochar. Biochar, as a porous material, has a large specific surface area due to its densely packed, open mesopores, providing abundant attachment sites for cobalt disulfide. With an appropriate amount of CoS2 or FeS2 uniformly loaded on the biochar surface, gaseous elemental mercury can easily contact the active centers of cobalt disulfide, achieving efficient and high-capacity adsorption of elemental mercury by the composite material.

[0067] In this invention, cobalt disulfide is applied to the structural composition of composite materials. Compared to Co9S8, CoS2 has a higher proportion of Co on its surface. 3+ The high content of active sites and active sulfur results in better mercury removal performance. The reaction mechanism involves mercury being removed by Co. 3+ Or S2 2- Oxidation eventually produces HgS, in which Co 3+ It is the main active site, and its mercury oxidation activity is higher than that of S2. 2- Stronger.

[0068] This invention provides a method for preparing a composite material, which can be used to prepare the composite material CoS2-h as described above, comprising the following steps:

[0069] S1. Dissolve the metal salt in a solvent and sonicate for 2-30 minutes to obtain a salt solution.

[0070] In some embodiments, the metal salt includes a cobalt salt or an iron salt, wherein the cobalt salt includes cobalt nitrate, cobalt acetate and / or cobalt chloride, and the iron salt includes ferric nitrate, ferric acetate and / or ferric chloride.

[0071] The solvent includes deionized water, and the ratio of the amount of metal salt added to the amount of deionized water can be 0.0015 mol: 10 to 50 ml.

[0072] S2. The porous carbon is immersed in the salt solution and subjected to hydrothermal reaction at 150-220°C for 4-20 hours. Solid-liquid separation is performed to obtain the precursor. The ratio of the amount of porous carbon to the amount of metal salt is 0.25-1.8 g: 0.0015 mol.

[0073] The step of impregnating the porous carbon in the salt solution includes: adding the porous carbon to the salt solution and stirring at a temperature of 10–50°C for 2–6 hours.

[0074] For example, the step of impregnating the porous carbon in the salt solution includes: adding the porous carbon to the salt solution and stirring at 40°C for 2 to 6 hours.

[0075] The reaction was carried out at 150–220℃ for 4–20 h, followed by solid-liquid separation to obtain the precursor. Specifically, the salt solution and porous carbon were transferred into a hydrothermal reactor and stirred at 150–220℃ for 4–20 h. After cooling, the solid and liquid were separated, and the precipitate was washed four times alternately with ethanol and pure water to obtain a black solid sample, i.e., the precursor.

[0076] For example, stirring can be performed at 180°C for 12 hours.

[0077] S3. The precursor is mixed with sulfur, and the mixture is heated to the vulcanization temperature at a heating rate of 5-20℃ / min, and held at the temperature for 1-4 hours to obtain a composite material; wherein the ratio of the amount of sulfur to the amount of the metal salt added is 0.12-0.36g:0.0015mol, and the vulcanization temperature is 250-500℃.

[0078] In some embodiments, the vulcanization temperature is 380–420°C. For example, the vulcanization temperature is 400°C.

[0079] In other embodiments, the precursor may be dried before the sulfur is added; wherein the drying temperature is 50-100°C and the drying time is 12-24 hours.

[0080] To ensure sufficient contact between the precursor and sulfur, in some embodiments, the dried precursor and sulfur can be ground evenly.

[0081] In this invention, sulfur sublimates at the sulfidation temperature and enters the surface and pores of the precursor, where it fully reacts with the metal salt attached to the precursor to generate CoS2 or FeS2.

[0082] Due to the unique gaseous form of sulfur after sublimation, the sulfidation reaction between sulfur and cobalt salt is uniform and without dead zones. The resulting cobalt disulfide is dispersed and densely distributed on the surface or in the pores of the carbon support. While ensuring sufficient active sites, it will not agglomerate and reduce exposure, nor will it overlap and block the pores, thus ensuring the adsorption capacity and adsorption efficiency of subsequent mercury adsorption.

[0083] In addition, this invention utilizes elemental sulfur sulfidation to provide more unsaturated sulfur: on the one hand, elemental sulfur can simultaneously achieve sulfur modification of activated carbon and synthesis of metal sulfides, both of which can provide unsaturated sulfur. On the other hand, the strong interaction between metal sulfides on the carbon surface and elemental sulfur can also inhibit the aggregation of long-chain sulfur, thereby promoting the formation of more unsaturated sulfur on the activated carbon surface. Specifically, metal sulfides can weaken the chemical bonds of the S8 ring of long-chain sulfur, thereby promoting the formation of short-chain sulfur molecules and avoiding the "shuttle effect" caused by polysulfide compounds.

[0084] The present invention also provides the application of the composite material as described above and / or the composite material prepared by the preparation method as described above in the treatment of mercury-containing flue gas.

[0085] Specifically, the steps include: introducing the mercury-containing flue gas into the composite material at a temperature of 25–75°C; wherein the mercury concentration in the mercury-containing flue gas is 10–500 μg / m³. 3 .

[0086] In some embodiments, the temperature of the mercury-containing flue gas is 40–60°C; for example, the temperature of the mercury-containing flue gas is 50°C.

[0087] In other embodiments, the mercury-containing flue gas includes one or more of N2, O2, SO2, NO, HCl, and H2O.

[0088] To facilitate a further understanding of the present invention by those skilled in the art, the following examples are provided:

[0089] Example 1

[0090] Preparation of CoS2-h:

[0091] Weigh 0.0015 mol (0.4365 g) of cobalt nitrate, dissolve it in 30 ml of deionized water, and sonicate for 5 minutes to obtain a cobalt salt solution.

[0092] Add 0.5 g of porous carbon to the cobalt salt solution and stir at 40°C for 4 hours. Transfer to a hydrothermal reactor and stir hydrothermally at 180°C for 12 hours. After cooling, wash four times alternately with ethanol and pure water to obtain a black solid sample, i.e., the precursor.

[0093] The precursor was dried at 70℃ for 18 hours, and then 0.24g of sulfur was added and ground until homogeneous. Under a N2 atmosphere, the temperature was increased at 5℃ / min and held at 250℃ (the sulfidation temperature) for 2 hours. The resulting CoS2 / mesoporous carbon composite adsorbent after cooling was named CoS2-h. The mass fraction of cobalt sulfide in the prepared CoS2-h was 16%.

[0094] Mercury removal performance test: Mercury-containing flue gas at 50°C (with nitrogen atmosphere as background, containing Hg) was introduced into the prepared CoS2-h. 0 Concentration of 130 μg / m 3 A 2-hour mercury removal performance test was conducted.

[0095] Example 2

[0096] Preparation of CoS2-h:

[0097] Weigh 0.0015 mol of cobalt nitrate, dissolve it in 30 ml of deionized water, and sonicate for 5 minutes to obtain a cobalt salt solution.

[0098] Add 0.5 g of porous carbon to the cobalt salt solution and stir at 40°C for 4 hours. Transfer to a hydrothermal reactor and stir hydrothermally at 180°C for 12 hours. After cooling, wash four times alternately with ethanol and pure water to obtain a black solid sample, i.e., the precursor.

[0099] The precursor was dried at 70℃ for 18 hours, and then 0.24g of sulfur was added and ground until homogeneous. Under a N2 atmosphere, the temperature was increased at 5℃ / min and held at 400℃ (the sulfidation temperature) for 2 hours. The resulting CoS2 / mesoporous carbon composite adsorbent after cooling was named CoS2-h. The mass fraction of cobalt sulfide in the prepared CoS2-h was 16%.

[0100] Mercury removal performance test: Mercury-containing flue gas at 50°C (with nitrogen atmosphere as background, containing Hg) was introduced into the prepared CoS2-h. 0 Concentration of 130 μg / m 3 A 2-hour mercury removal performance test was conducted.

[0101] The specific surface area, pore volume, and pore size of CoS2-h were tested using an N2 adsorption / desorption method. Figure 1 As shown, the nitrogen adsorption-desorption curves of CoS2-h exhibit a clear inflection point around P / P0 = 0.1, representing the adsorption capacity when the micropores are completely filled. The specific surface area of ​​the composite material is 625 m² / g. 2 / g, total pore volume is 0.299cm³ 3 / g, with an average pore size of 1.9047nm.

[0102] XRD analysis of CoS2-h was performed, referencing... Figure 2 The broad diffraction peak near 24° corresponds to amorphous carbon, while multiple diffraction peaks at 27.8°, 32.3°, 36.2°, 39.8°, 46.3°, 54.9°, 60.1°, and 62.7° correspond to the (111), (200), (210), (211), (220), (311), (023), and (321) crystal planes of cubic CoS2. This confirms that the synthesized material is a composite material of CoS2 and carbon.

[0103] The microstructure and structure of CoS2-H were further investigated using SEM and HR-TEM. Figure 3 As shown, CoS2-h exhibits a uniform spherical structure with cobalt disulfide uniformly loaded on its surface, without forming agglomerates or stacks.

[0104] HR-TEM images show clear lattice fringes (reference) Figure 4 The interplanar spacing is 0.270 nm, corresponding to the CoS2 phase (200) plane, which is consistent with the XRD results.

[0105] refer to Figure 5 The mapping diagram shows that Co and S elements are evenly distributed on the surface of the carbon support, and the S on the adsorbent surface is significantly more than Co, indicating that the oversulfurization method achieves surface sulfur enrichment.

[0106] Figure 6 The EDS spot scan spectrum showed that the atomic ratio of Co to S was 1:2. This further demonstrates that the present invention synthesized a CoS2 / carbon composite material with a mesoporous structure on a mesoporous carbon substrate through impregnation and sulfur sulfidation.

[0107] Example 3

[0108] Preparation of CoS2-h:

[0109] Weigh 0.0015 mol of cobalt nitrate, dissolve it in 30 ml of deionized water, and sonicate for 5 minutes to obtain a cobalt salt solution.

[0110] Add 0.5 g of porous carbon to the cobalt salt solution and stir at 40°C for 4 hours. Transfer to a hydrothermal reactor and stir hydrothermally at 180°C for 12 hours. After cooling, wash four times alternately with ethanol and pure water to obtain a black solid sample, i.e., the precursor.

[0111] The precursor was dried at 70℃ for 18 hours, and then 0.24g of sulfur was added and ground until homogeneous. Under a N2 atmosphere, the temperature was increased at 5℃ / min and held at 500℃ (the sulfidation temperature) for 2 hours. The resulting CoS2 / mesoporous carbon composite adsorbent after cooling was named CoS2-h. The mass fraction of cobalt sulfide in the prepared CoS2-h was 16%.

[0112] Mercury removal performance test: Mercury-containing flue gas at 50°C (with nitrogen atmosphere as background, containing Hg) was introduced into the prepared CoS2-h. 0 Concentration of 130 μg / m 3 A 2-hour mercury removal performance test was conducted.

[0113] The mercury removal performance of the adsorbent at different sulfidation temperatures in Examples 1-3 is as follows: Figure 7 As shown. The adsorbent Hg prepared by sulfidation at 400℃. 0 The adsorbent prepared by sulfidation at 250℃ exhibited the best mercury removal performance, maintaining a 100% removal efficiency for 60 minutes. The highest mercury removal efficiency was 90%, but this dropped rapidly, reaching only 50% after 50 minutes. This is presumably because the sulfidation temperature was too low, preventing the sulfur from sublimating into gas and fully reacting with the precursor. The adsorbent prepared by sulfidation at 500℃ initially showed a 100% mercury removal efficiency, but this dropped significantly after 20 minutes, presumably because the sulfur volatilized too quickly at high temperatures, leaving insufficient time to react with the precursor. Therefore, the sulfidation temperature determines the formation of CoS2 on the carbon support; excessively high or low sulfidation temperatures will lead to incomplete sulfidation of the precursor, preventing the formation of CoS2 and thus reducing its Hg content. 0 The reason for poor capture capability.

[0114] Example 4

[0115] Effect of flue gas temperature on the mercury removal performance of composite materials:

[0116] The composite material prepared in Example 2 was placed in a tubular reactor, and mercury-containing flue gas at temperatures ranging from 25 to 100°C was introduced into it. The mercury-containing flue gas had a composition of 130 μg / m³. 3 Hg 0 N2 is used as a balancing gas.

[0117] Mercury removal performance of composite materials under pure nitrogen atmosphere and different flue gas temperatures is as follows: Figure 8 As shown in the figure, CoS2-h exhibits the best mercury removal performance at a flue gas temperature of 50℃. At a flue gas temperature of 25℃, the mercury removal efficiency remains at 100% for 30 minutes, but drops to around 60% after 120 minutes. At 75℃, the mercury removal efficiency is still 100% after 50 minutes, but drops to 80% after 120 minutes. At 100℃, the mercury removal efficiency begins to decline rapidly after 20 minutes, dropping to around 60% after 90 minutes.

[0118] Both excessively low and excessively high flue gas temperatures can lead to reduced mercury removal efficiency, possibly due to Hg 0 The adsorption on the CoS2-h surface is chemisorption. Too low a temperature is not conducive to chemisorption, but too high a temperature in the flue gas will cause some of the adsorbed mercury to desorb.

[0119] Example 5

[0120] Tests on the mercury removal performance of mercury removal materials based on flue gas composition:

[0121] The composite material prepared in Example 2 was placed in a tubular reactor, and five groups of mercury-containing flue gases (Hg in the mercury-containing flue gas) were respectively introduced into it at 50°C with a nitrogen background, containing 6% O2, 6% SO2, 400ppm NO, 10ppm HCl, and 8% water vapor. 0 The concentration was 130 μg / m³. 3 (This is used to conduct a two-hour mercury removal test on the flue gas.)

[0122] The experimental results of this embodiment are as follows: Figure 9 As shown, compared with the 85% mercury removal efficiency under pure N2 atmosphere, the mercury removal efficiency of four groups of adsorbents (6% O2, 6% SO2, 400ppm NO, and 10ppm HCl) increased to 100%, indicating that O2, SO2, NO, and HCl in the flue gas can all promote CoS2-h mercury removal. It can be seen that the composite material possesses highly efficient sulfur-resistant mercury removal performance in simulated non-ferrous metal smelting flue gas.

[0123] In comparison, H2O has a greater effect on Hg. 0The removal effect was negatively affected; the mercury removal efficiency of the CoS2 / PC adsorbent decreased after adding 8% water vapor to the flue gas, possibly due to the presence of Hg. 0 This is caused by competitive adsorption with H2O.

[0124] Example 6

[0125] Mercury adsorption capacity test:

[0126] In Example 5, a long-term adsorption experiment was conducted under simulated non-ferrous metal smelting flue gas to verify the adsorption of Hg by CoS2-h prepared in Example 2. 0 The stability and adsorption capacity, such as Figure 10 As shown. The composition of the non-ferrous metal smelting flue gas includes: 6% SO2, 6% O2, and 8% H2O; the Hg in the metal smelting flue gas... 0 Concentration of 130 μg / m 3 .

[0127] It can be seen that the initial Hg 0 The removal efficiency was close to 100%, decreasing to 20% after 11,000 minutes. A 10 mg sample was used during the test. The calculated Hg of CoS2-h was... 0 When the penetration rate is 80%, the adsorption capacity is 41.4 mg / g.

[0128] Example 7

[0129] FeS2 / C preparation

[0130] 0.001 mol of Fe(NO3)3·9H2O was dissolved in 20 mL of deionized water, and then 0.3 g of porous carbon was added. After stirring for 6 h, the mixture was transferred to a 100 mL autoclave and reacted at 180 °C for 12 h. The mixture was then filtered, washed repeatedly with deionized water and anhydrous ethanol, and dried at 60 °C for 12 h to obtain the precursor.

[0131] The obtained precursor was mixed with 0.2 g of elemental sulfur and then heated for 2 h in a N2 atmosphere at a specific sulfidation temperature. The sulfidation reactions were carried out at 200, 400, and 500 °C, respectively. The resulting sample was denoted as FeS2-y, where y is the sulfidation temperature. (For example, FeS2-400 indicates a sample obtained by sulfidation at 400 °C; porous carbon was directly sulfidated with elemental sulfur to obtain S / C as a blank sample.)

[0132] S / C, FeS x The specific surface areas of BET at -400 are 1184 and 708 m², respectively. 2 .g -1 This indicates that elemental sulfur and FeS x The load will occupy the pore structure of porous carbon. FeS xThe pore size and pore volume of -400 are 2.21 nm and 0.39 cm, respectively. 3 / g. The mesoporous structure of the FeS2 / C adsorbent is beneficial for mass transfer and for the capture of elemental mercury.

[0133] like Figure 13 As shown, FeS was analyzed using XRD. x The crystal structure of sample C is shown in the following results. Figure 13 As shown. FeS x -400 and FeS x The XRD pattern at -500 nm highly matches the diffraction peaks of pyrite FeS2 (PDF#12-1340), both showing obvious characteristic peaks of the FeS2 phase. x FeS has a higher crystallinity at -500. x The XRD pattern at -200°C matches the characteristic peaks of hematite Fe2O3 (PDF#33-0664). Figure 14 This indicates that FeS x / C precursor (FeS) x The peaks of the iron salt (-P) match those of hematite Fe2O3 (PDF#33-0664). The results indicate that the iron salt exists as hematite Fe2O3 after hydrothermal treatment, and iron sulfidation is difficult to achieve at low temperatures.

[0134] like Figure 15 As shown, using FeS x The Raman spectrum of / C further confirmed that FeS x -400, FeS x -500 and FeS x The crystal structure is -200. Three samples were observed at 221.3, 280.4, and 395.6 cm⁻¹. -1 Three distinct peaks were observed, corresponding to the characteristic peaks of FeS. With increasing sulfidation temperature, the two Fe-S vibrational modes shifted to lower energy regions, and FeS... x The vibration intensity is highest at -400°C at these three locations. Furthermore, with increasing vulcanization temperature, the vibration intensity increases at 350.5, 382.5, and 438.6 cm⁻¹. -1 Three weak peaks appear at this point, which closely matches the Raman peaks of pyrite FeS2. x The vibration intensity was also greatest at -400°C in these three locations, FeS x Compared to -500, the energy shifts to a higher energy range. This indicates that appropriate temperatures are required for the Raman peaks of iron-sulfur compounds to appear and for higher Fe-S and SS vibrational frequencies to be guaranteed.

[0135] like Figure 16 As shown, the morphology and elemental distribution of the samples were analyzed using SEM and EDS. Figure 16 As shown in (ac), SEM analysis indicates that FeSx -200, FeS x -400 and FeS x -500 exhibits a typical spherical structure, with iron-sulfur compound particles and agglomerates covering the surface of the carbon spheres, indicating that electrostatic or van der Waals forces on the porous carbon surface can anchor iron-sulfur compounds. Figure 16 As shown in (df), EDS analysis identified C, Fe, and S elements, confirming the composite material structure, FeS x -200, FeS x -400 and FeS x The S / Fe ratios at -500 were 29:1, 3:1, and 1.75:1, respectively.

[0136] XRD analysis shows that at sulfidation temperatures of 200℃ and 400℃, excess unreacted elemental sulfur is likely to be adsorbed onto porous carbon, thus FeS x -200 has more elemental sulfur adsorbed on the carbon spheres; when the sulfidation temperature is 500℃, it is higher than the boiling point of elemental sulfur 444.6℃, thus causing insufficient sulfur and resulting in a sulfur-to-iron ratio less than the theoretical 2:1.

[0137] Example 8

[0138] The sample's effect on Hg was tested at 50℃ under a N2 atmosphere. 0 FeS removal performance x After mercury removal at -400°C, UsedFeS is obtained. x -400, the result is as follows Figure 17 As shown. Figure 17 As shown, under N2 conditions, FeS x The highest mercury removal efficiency, reaching 80%, is achieved at -400°C. Mercury removal efficiency decreases with decreasing sulfidation temperature, which can be attributed to the blockage of long-chain sulfur. Mercury removal efficiency also decreases with increasing sulfidation temperature, which can be attributed to increased crystallinity leading to a decrease in reactive sulfur.

[0139] In addition, the effect of flue gas temperature on Hg removal by FeS2 / C-400 under N2+6%SO2+6%O2 conditions was investigated. 0 The impact, such as Figure 18 As shown. At 50℃, FeS2 / C-400 affects Hg. 0 The removal rate remains at around 100%, decreasing as the flue gas temperature increases. Figure 19 FeS shown x -400 adsorbs Hg at 125℃ 0 The mercury removal efficiency was 34% after 1 hour. After lowering the reaction temperature to 50℃, the mercury removal efficiency of the sample rapidly increased to 99.5%, and remained at 91% after 1 hour. Figure 19 and Figure 20 It can be seen that FeS x The main reason why the mercury removal efficiency is low at -400°C is that high temperature promotes the desorption and separation of adsorbed mercury.

[0140] in addition, Figure 20 As shown, at 50℃, the mercury removal efficiencies of S / C under N2 and N2+6%SO2+6%O2 atmospheres are 75% and 81%, respectively. This indicates that O2 and SO2 have a significant effect on the removal of mercury from S / C and FeS. x -400 Hg removal 0 They have a positive effect, as they can regenerate consumed active sites.

[0141] Example 9

[0142] Further research was conducted on the effects of flue gas components on Hg. 0 The impact of removal performance, such as Figure 21 As shown. FeS x -400 Hg 0 The removal efficiency increases with increasing concentrations of SO2, NO, HCl, and H2O. When the SO2 concentration is 3%, the NO concentration is 75 ppm, the HCl concentration is 10 ppm, and the H2O concentration is 9%, the FeS... x The mercury removal efficiency at -400°C reached 100%.

[0143] As the concentration of these flue gas components further increased, the mercury removal efficiency remained stable at 100%. Meanwhile, O2's effect on Hg... 0 The effect of Hg removal is negligible. Therefore, SO2, NO, HCl, and H2O were identified as promoters of Hg removal. 0 Positive factors in capture.

[0144] Example 10

[0145] To test FeS x The mercury adsorption capacity was -400 g / L. A long-term mercury removal test was conducted at 50°C under simulated flue gas conditions of N2 + 6% SO2 + 6% O2 until an 80% breakthrough was achieved. 0 The adsorption capacity is calculated using equation (2):

[0146]

[0147]

[0148] Get FeS x -400 Hg 0 The adsorption capacity is 48 mg·g -1 .

[0149] Example 11

[0150] In Example 11, all other conditions remained unchanged except for the composition of the simulated flue gas, and a long-term mercury removal test was conducted until an 80% breakthrough was achieved. The 80% breakthrough curve is shown below. Figure 22 As shown, the simulated flue gas composition includes: N2 + 6% O2 + 6% SO2 + 400ppm NO + 10ppm HCl.

[0151] Depend on Figure 22 It can be seen that FeS x -400 Hg 0 The adsorption capacity is 119 mg·g -1 (80% of the breakthrough threshold). Under the same experimental conditions, S / C was used to treat Hg. 0 The adsorption capacity was directly compared; at 80% breakthrough, the S / C ratio for Hg was [value missing]. 0 The adsorption capacity is 2.5 mg·g. -1 The results showed that FeS x -400 Hg 0 The adsorption capacity of FeS2 is much greater than that of S / C, which indicates that the improved mercury removal performance of FeS2 / C-400 is mainly due to FeS2 being loaded onto porous carbon.

[0152] For ease of comparison, Table 1 summarizes the effects of other iron-based adsorbents on Hg reported in the literature. 0 The equilibrium adsorption amount. It can be observed that FeS x -400 Hg 0 Its adsorption capacity is far superior to all the adsorbents used for comparison, and the operating cost of adsorbing mercury is only $15.23 / kg mercury, which is much lower than the $157 / kg mercury in existing studies.

[0153] Table 1 has reported the effects of sulfur-containing adsorbents on Hg. 0 Adsorption performance

[0154]

[0155] Example 12

[0156] The surface chemical properties of the samples before and after treatment were studied using XPS, and the results are as follows: Figure 23 As shown.

[0157] Figure 23 (a) indicates that the Fe 2p spectrum of XPS changed significantly before and after treatment, compared to FeS x -400, O2-FeS x -400 and Used FeS xThe Fe(III)-S ratio at -400 decreased from 66.61% to 54.27% and 54.66%, respectively, and the Fe(III)-S peak also shifted to the higher energy region, indicating that Fe(III)-S lost electrons after O2 and Hg adsorption treatment.

[0158] Figure 23 (b) indicates that the S2p spectrum of XPS also changed significantly before and after treatment, O2-FeS x -400 and UsedFeS x -400 CS and S n 2- (n>2) The proportion decreases, S2 2- As the proportion increases, their peaks shift to lower energy regions. These results indicate that O2 and Hg participate in the adsorbent reaction as electron acceptors. Figure 23 (c) Indicating the use of FeS after mercury adsorption x The Hg4f spectrum at -400 eV has characteristic peaks at 101.4 and 104.7 eV corresponding to HgS.

[0159] Figure 23 (d) indicates that the Hg adsorbed under N2 and atmospheric conditions exists in the form of HgS. XPS analysis of Used FeS x The chemical state of mercury adsorbed at -400, such as Figure 23 As shown in (c), the two peaks centered at 101.4 eV (Hg 4f7 / 2) and 104.7 eV (Hg 4f5 / 2) belong to Hg. 2+ This indicates that the oxidation reaction occurs in the gaseous state of Hg. 0 This occurs during the adsorption process. The specific forms of mercury present are further clarified through Hg-TPD experiments, such as... Figure 23 As shown in (d).

[0160] Heating rate 10℃·min -1 Under pure N2 and 6% SO2 + 6% O2 conditions, respectively, Hg was used 0 Pre-adsorbed FeS x Hg-TPD tests were conducted at -400°C. The mercury decomposition peak of the tested sample appeared in the temperature range of 260–280°C, indicating that Hg... 0 After capture, HgS formed on the sample surface. The mercury decomposition peak under 6% SO2 + 6% O2 conditions appeared at 280℃, significantly higher than under N2 conditions, confirming the presence of used FeS. x Mercury on a -400 surface exhibits good thermal stability under conditions of 6% SO2 + 6% O2.

[0161] In summary, FeS x -200 and FeS xThe poor mercury removal performance at -500 is due to the low levels of sulfur and iron active sites. The sulfur active sites here are mainly CS and S. n 2- (n>2), the iron active sites are mainly Fe(III)-S. Although FeS x -200 CS / S 0 Higher, but mainly S 0 HgS exists in the form of Hg on the adsorbent surface. 0 Formed by adsorption.

[0162] Hg adsorption at Fe(III)-S sites 0 The process can be described as follows:

[0163] Hg 0 (g)+Fe(III)-S n (n>2)→[Hg.Fe]-S n

[0164] [Hg.Fe]-S n →Fe(III)-S n-1 +HgS

[0165] For the adsorption of Hg at sulfur sites 0 The process can be described as follows:

[0166] Hg 0 (g)+S n 2- (n>2)→[Hg.S n ]

[0167] [Hg.S n →HgS+S n-1

[0168] Hg 0 (g) + CS → C - [S.Hg]

[0169] C-[S.Hg]→C+HgS

[0170] Comparative Example 1

[0171] The other steps in Example 2 remain unchanged. After the precursor is dried, the dried precursor is calcined in air at a temperature of 200-600°C for 1 hour. The calcined sample is then subjected to subsequent operations, which are the same as in Example 2.

[0172] The mercury removal properties of the composite material in Example 2 and the composite material under different calcination temperatures are as follows: Figure 11 As shown.

[0173] Uncalcined adsorbents exhibited the best mercury removal performance, maintaining a mercury removal efficiency of 100% for 70 minutes. Figure 11 At 120 minutes, the mercury removal efficiency was still above 80%. The highest mercury removal efficiency for adsorbents prepared by calcination at 200℃–400℃ was 100%. However, the mercury removal efficiency began to decline after 20 minutes, reaching a maximum of only 60% at 120 minutes. The highest mercury removal efficiency for adsorbents prepared by calcination at 600℃ was less than 90%, and the efficiency dropped rapidly, decreasing to 50% in less than 20 minutes. It is speculated that high-temperature calcination caused the agglomeration of active particles on the adsorbent surface, affecting the subsequent sulfidation reaction. Simultaneously, the agglomerated particles reduced the interaction between the active material and the interfacial Hg. 0 The limited contact area results in poor mercury removal performance.

[0174] Comparative Example 2

[0175] The preparation of adsorbent CoS2 / PC by hydrothermal desulfurization includes the following steps:

[0176] Add 0.0015 mol cobalt nitrate (Co(NO3)2·6H2O) to 30 mL of deionized water, sonicate for 5 minutes, then sonicate 0.0045 mol thiourea into the above solution, add 0.5 g of porous carbon, and stir at 40 °C for 4 hours. Transfer the resulting mixture to a 200 mL autoclave lined with PTFE, and react at 180 °C for 12 hours. After washing the obtained composite material 3-4 times with ethanol and water, dry it in a vacuum oven at 70 °C for 18 hours to obtain the CoS2 / carbon composite material (CoS2 / PC).

[0177] CoS2 / PC was calcined at 800℃ in pure N2 (100mL / min) for 2 hours at a heating rate of 5℃ / min to obtain Co9S8 / carbon composite material (Co9S8 / PC).

[0178] The mercury removal performance of the composite material CoS2-h prepared in Example 2 and CoS2 / PC was tested. The mass fraction of cobalt sulfide in the prepared CoS2 / PC was 16.2%.

[0179] refer to Figure 12 As can be seen, the mercury removal performance of CoS2-h prepared in this invention is further improved compared with the adsorbent CoS2 / PC synthesized by hydrothermal thiourea sulfidation, and the efficient mercury removal time is longer. After 120 minutes, the mercury removal efficiency of CoS2-h is 20% higher than that of CoS2 / PC. It can be seen that sulfur has a stronger sulfidation ability than organic sulfur sources (thiourea), and the over-sulfidation method increases the surface active sulfur content.

[0180] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method of preparing a composite material, characterized by, The preparation method comprises the following steps: dissolving a metal salt in a solvent, and ultrasonicating for 2-30 min to obtain a salt solution, wherein the metal salt is an iron salt; immersing porous carbon in the salt solution, and reacting under hydrothermal conditions at 150-220 ℃ for 4-20 h to obtain a precursor, wherein the ratio of the input amount of the porous carbon to the metal salt is 0.25-1.8 g:0.0015 mol; mixing the precursor with sulfur, and heating to a sulfidation temperature at a heating rate of 5-20 ℃ / min, and keeping the temperature for 1-4 h to obtain a composite material, wherein the ratio of the added amount of the sulfur to the metal salt is 0.12-0.36 g:0.0015 mol, and the sulfidation temperature is 380-420 ℃; the composite material comprises sulfides and biomass carbon, the sulfides are loaded on the biomass carbon, and the sulfides are FeS2; and the mass percentage of the sulfides in the biomass carbon is 5-35%.

2. The production method according to claim 1, characterized by, the mass percentage of the sulfides in the biomass carbon is 12-20%.

3. The preparation method according to claim 1, characterized in that, the iron salt is ferric nitrate, ferric acetate and / or ferric chloride.

4. The method of claim 1, wherein, the solvent comprises deionized water, and the ratio of the added amount of the metal salt to the deionized water is 0.0015 mol:10-50 ml.

5. The preparation method according to claim 1, characterized in that, immersing the porous carbon in the salt solution comprises adding the porous carbon to the salt solution, and stirring at 10-50 ℃ for 2-6 h.

6. The method of claim 1, wherein, before the sulfur is added, the precursor is subjected to a drying treatment, wherein the treatment temperature of the drying treatment is 50-100 ℃, and the treatment time of the drying treatment is 12-24 h. 7.A composite material prepared by the preparation method according to any one of claims 1-6. 8.A use of the composite material prepared by the preparation method according to any one of claims 1-6 or the composite material according to claim 7 in treating mercury-containing flue gas.

9. Use according to claim 8, characterized in that, The method comprises the following steps: introducing the mercury-containing flue gas into the composite material; wherein the temperature of the mercury-containing flue gas is 25-75 DEG C, the mercury concentration in the mercury-containing flue gas is 10-500 ug / m 3 , and the mass / volume ratio of the composite material to the mercury-containing flue gas is 5-40 g / m 3 .

10. Use according to claim 9, characterized in that, the mercury-containing flue gas comprises one or more of N2, O2, SO2, NO, HCl and H2O.

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