A method for preparing metal sulfide / carbon composite material based on multi-waste pyrolysis reconstruction-vapor deposition and application

Abstract

The application discloses a kind of metal sulfide / carbon composite material preparation method and application based on multi-waste pyrolysis reconstruction-vapor deposition.Method includes: waste ion exchange resin is pretreated, then metal oxide / carbon composite material is obtained by pyrolysis component reconstruction, placed in tubular vapor deposition device, industrial hydrogen sulfide waste gas is used as gas phase active sulfur source and is input to carry out chemical in-situ vapor deposition reaction, directional adsorption to material is carried out directional conversion, and metal sulfide / carbon composite material is obtained, and used as adsorbent for gaseous elemental mercury adsorption removal.The application provides the implementation mode of multi-source hazardous waste coordination resource, effectively solves the disposal problem of waste ion exchange resin and hydrogen sulfide waste gas pollution problem;Provide the preparation path of high-performance metal sulfide / carbon composite material, and the performance is excellent in the removal of heavy metal mercury pollutant;Provide simple and efficient metal sulfide preparation process, make process flow simple, and strong implementability.

Description

Technical Field

[0001] This invention relates to a method for preparing a metal sulfide / carbon composite material, and relates to the technical fields of multi-source hazardous waste synergistic resource utilization and stationary source emission sulfur / mercury pollutant control. Specifically, it relates to a method for preparing a metal sulfide / carbon composite material based on multi-waste pyrolysis reconstruction-vapor phase deposition and its application. Background Technology

[0002] Mercury is a global priority pollutant with strong biotoxicity, environmental persistence, and bioaccumulation. Mercury emissions from stationary sources (coal combustion, non-ferrous metallurgy, waste incineration, etc.) mainly consist of gaseous elemental mercury (Hg). 0 Gaseous divalent mercury (Hg) 2+ and particulate mercury (Hg) p Among them, gaseous elemental mercury (Hg) 0 Due to its high volatility, stable chemical properties, and extremely poor water solubility, mercury is difficult to remove through conventional flue gas purification equipment such as desulfurization, denitrification, and dust removal. This is the core challenge in controlling mercury pollution in flue gas and a major source of atmospheric mercury emissions and ecological risks.

[0003] Adsorbent injection technology is currently the most effective method for treating gaseous elemental mercury (Hg) in flue gas. 0 Mercury adsorbents are one of the mainstream technologies for control, and have advantages such as simple process, high removal efficiency, and strong adaptability. However, commercial adsorbents based on activated carbon have problems such as high cost, easy poisoning and deactivation in complex flue gas, and poor sulfur resistance. In particular, under sulfur-containing flue gas conditions, active sites are easily covered or oxidized and consumed, resulting in a significant decrease in mercury adsorption capacity and stability, which limits their large-scale engineering application.

[0004] Waste ion exchange resins are widely generated in nuclear power plant water treatment, thermal power boiler water softening, chemical separation, pharmaceutical refining, and electronics industry wastewater treatment, and are classified as typical hazardous waste. Waste resins not only contain high-molecular-weight organic frameworks but also often accumulate metal ions such as Cu, Zn, Ni, Fe, Pb, and Cr, and some contain radioactive pollutants, posing significant environmental risks. Currently, the mainstream disposal methods are secure landfill and high-temperature incineration. Landfilling consumes land resources and carries the risk of heavy metal leaching. Incineration is costly and easily generates secondary pollution such as dioxins and VOCs. Waste resins have a carbon content as high as 60%–80% and an oxygen content of approximately 5%–10%. Through pyrolysis, they can form porous carbon carriers, with metal ions uniformly dispersed at the ionic level on the resin framework. After pyrolysis, they can be converted in situ into metal oxides and are not prone to aggregation, possessing extremely high resource potential. How to achieve the safe disposal and high-value utilization of hazardous waste resins has become a common technological requirement in the industrial sector.

[0005] Hydrogen sulfide (H2S) is widely present in industrial waste gases from coal gasification, natural gas purification, petroleum refining, and non-ferrous metal smelting, with concentrations ranging from tens of ppm to several percent (volume fractions). H2S is highly corrosive and biotoxic; after emission, it is easily oxidized to SO2, making it a significant precursor to acid rain and fine particulate matter. Furthermore, as a strong reducing gas, H2S preferentially consumes oxidants and catalyst active sites, significantly inhibiting the production of hydrogen sulfide (Hg). 0 Oxidation and removal of sulfur. Traditional H2S treatment mainly relies on alkaline absorption, dry adsorption, and incineration desulfurization, with the goal of achieving emission standards but failing to realize high-value utilization of sulfur resources. It is easy to generate secondary waste liquid or waste residue, resulting in a low degree of resource utilization.

[0006] However, a mature technology system has not yet been formed, and there is a lack of methods to efficiently integrate waste resin pyrolysis reconstruction, H2S vapor deposition sulfidation-in-situ construction of metal sulfides, and flue gas mercury removal. Summary of the Invention

[0007] To address the problems existing in the background technology, this invention provides a method for preparing metal sulfide / carbon composite materials based on multi-waste pyrolysis reconstruction-gas phase deposition and its application. This invention addresses the technical bottlenecks of existing waste ion exchange resins, such as difficult hazardous waste disposal, limited resource utilization pathways, low added value in H2S waste gas treatment, and high cost, poor sulfur resistance, and easy deactivation of existing mercury removal adsorbents. Using waste ion exchange resin as a carbon source and metal precursor, and hydrogen sulfide (H2S) waste gas as an active sulfur source, this invention prepares metal sulfide / carbon composite materials in situ through pyrolysis reconstruction-gas phase deposition, and applies them to gaseous elemental mercury (Hg). 0 Removal in progress.

[0008] The technical solution adopted in this invention is: I. A method for preparing metal sulfide / carbon composite materials based on multi-waste pyrolysis reconstruction-vapor phase deposition, comprising: Step S1) The waste ion exchange resin particles after wastewater treatment are recycled and pretreated, and then high-temperature carbonization and precursor oxidation reaction are carried out through pyrolysis component reconstruction to obtain metal oxide / carbon composite material; specific wastewater treatment scenarios mainly include nuclear power radioactive wastewater, boiler softening wastewater, chemical separation process wastewater, pharmaceutical refining process wastewater and electronic industry wastewater, etc.

[0009] Step S2) The metal oxide / carbon composite material is placed in a tubular vapor deposition apparatus. Industrial hydrogen sulfide (H2S) waste gas, after gas treatment, is recovered and used as a gaseous active sulfur source. This gas is then introduced into the tubular vapor deposition apparatus for in-situ chemical vapor deposition, where it is directionally adsorbed onto the metal oxide / carbon composite material to reconstruct the surface active phase, thus obtaining the metal sulfide / carbon composite material. Specific gas treatment scenarios mainly include coal gas purification, natural gas purification, petroleum refining gas purification, and non-ferrous metal smelting flue gas purification.

[0010] In step S1), the waste ion exchange resin particles are pretreated by sequentially washing and drying to remove surface impurities, free water, and large foreign particles, resulting in pretreated waste ion exchange resin particles. Then, pyrolysis component reconstruction is performed by placing the pretreated waste ion exchange resin particles in a tubular furnace pyrolysis device for high-temperature pyrolysis. During the reaction, the organic framework of the pretreated waste ion exchange resin particles undergoes carbonization to form a porous carbon matrix, and the metal ions loaded in the pretreated waste ion exchange resin particles undergo oxidation to generate metal oxide nanoparticles in situ, while retaining the original spherical porous mass transfer structure of the pretreated waste ion exchange resin particles. After cooling to room temperature, a metal oxide / carbon composite material is obtained.

[0011] In step S1), the waste ion exchange resin particles are loaded with Cu. 2+ Zn 2+ Fe 2+ Fe 3+ Ni 2+ A cation exchange resin containing one or more metal ions, wherein the metal ions undergo an oxidation reaction to generate in-situ metal oxides, which are one or more of CuO, Cu2O, ZnO, Fe2O3, Fe3O4, NiO, etc.

[0012] In step S1), during pretreatment, deionized water is used instead of tap water and mineral water for washing to ensure that impurities, residual agents and soluble salts attached to the resin surface are fully removed; the drying temperature does not exceed 100 ℃ to avoid the precipitation of small molecule volatiles at high temperatures and environmental pollution.

[0013] In step S1), a high-temperature pyrolysis reaction is carried out under an inert atmosphere or an oxidizing atmosphere. The inert atmosphere is one or a mixture of nitrogen and argon, and the oxidizing atmosphere is oxygen, a mixture of oxygen and inert gases, air, or a mixture of air and inert gases. The total flow rate of the inert atmosphere or oxidizing atmosphere is 50~200 mL / min, which can effectively prevent the reduction of metal ions and the coating of metal oxides with carbon during the pyrolysis process. The heating rate of the high-temperature pyrolysis reaction is 2~10℃ / min, the temperature is 500~700℃, and the holding time after reaching the preset target temperature is 1~4 h. By adjusting the pyrolysis parameters, it is ensured that the organic framework is fully carbonized and the metal ions are completely oxidized, while avoiding the collapse of the porous structure due to excessive heating.

[0014] In step S2), when industrial hydrogen sulfide (H2S) waste gas undergoes in-situ chemical vapor deposition, the reaction temperature is controlled at 50-300 °C, the volume fraction of hydrogen sulfide (H2S) in the industrial hydrogen sulfide (H2S) waste gas is 5%-50%, and the reaction time is 0.5-3 h. This parameter range ensures that the metal oxide is fully converted into metal sulfides, while avoiding excessive reaction that could lead to agglomeration of active sites or destruction of the carbon support structure. The in-situ vapor deposition reaction between hydrogen sulfide (H2S) and the metal oxide in the metal oxide / carbon composite material directionally converts the metal oxide into active sites for metal sulfides. During the reaction, the spherical porous mass transfer structure of the metal oxide / carbon composite material is preserved, ensuring that the active sites for metal sulfides are uniformly dispersed on the surface of the carbon support. After cooling to room temperature, the final metal sulfide / carbon composite material is obtained.

[0015] In step S2), during the in-situ chemical vapor deposition reaction of industrial hydrogen sulfide (H2S) waste gas, an inert carrier gas is simultaneously introduced. The inert carrier gas is either nitrogen or argon, used to dilute the industrial hydrogen sulfide (H2S) waste gas and promote uniform gas distribution. The total gas flow rate is 200-500 mL / min to ensure uniform sulfidation reaction. After the reaction is completed, the inert carrier gas is continued to purge the residual hydrogen sulfide (H2S) gas in the tube-type vapor deposition device for 10-30 min to avoid toxic gas residue and ensure operational safety.

[0016] II. A metal sulfide / carbon composite material based on multi-waste pyrolysis reconstruction-vapor phase deposition: The metal sulfide / carbon composite material is prepared by the method described above.

[0017] III. An application of a metal sulfide / carbon composite material based on multi-waste pyrolysis reconstruction-vapor phase deposition: the application includes its use as an adsorbent for immobilizing gaseous elemental mercury (Hg) in source flue gas. 0 The adsorption and removal process involves stationary sources such as coal combustion, metallurgy, cement production, and waste incineration.

[0018] IV. An application method for metal sulfide / carbon composite materials based on multi-waste pyrolysis reconstruction-vapor phase deposition: The application method involves introducing the metal sulfide / carbon composite material containing gaseous elemental mercury (Hg) through spraying or fixed-bed packing. 0 In the stationary source flue gas pollutant control system, the adsorption temperature is controlled at 50~150 ℃ to allow gaseous elemental mercury (Hg) to be adsorbed. 0 A chemical adsorption reaction occurs between the mercury sulfide active sites on the surface of the metal sulfide / carbon composite material, generating a stable mercury sulfide (HgS) compound, thereby immobilizing gaseous elemental mercury (Hg) in the source flue gas. 0 The efficient removal and permanent solidification of mercury in exhaust gas are used to control mercury pollution.

[0019] This invention uses industrial waste ion exchange resin as a carbon source and metal precursor, achieving carbonization of the resin's organic framework and oxidative reconstruction of loaded metal ions through high-temperature pyrolysis, resulting in an in-situ spherical porous metal oxide / carbon composite material. Then, using industrial H2S waste gas as a gaseous sulfur source, the metal oxide is converted in-situ into metal sulfide active sites through a vapor-phase deposition reaction. While retaining the original pore structure and mass transfer advantages of the resin, a highly active and selective sulfur site adsorption material is constructed. Finally, this functionalized material is applied to stationary source flue gas Hg. 0 The efficient adsorption and removal achieves the synergistic goals of hazardous waste resource utilization, waste gas value-added processing, and deep flue gas purification.

[0020] Hydrogen sulfide (H2S) itself is an excellent sulfur source and can be used to construct active sites for metal sulfides in situ; the surface of metal sulfide materials has a large number of coordination-unsaturated active sulfur sites, which are effective for gaseous elemental mercury (Hg). 0 It possesses extremely strong chemical adsorption and bonding capabilities, with adsorption capacity and selectivity significantly superior to conventional activated carbon. Simultaneously, the metal sulfide exhibits excellent sulfur resistance, is less prone to poisoning by sulfur components in flue gas, and the resulting gaseous elemental mercury (HgS) exhibits extremely high thermal stability, enabling permanent mercury solidification and preventing secondary release. It is a highly promising and efficient mercury removal material. In summary, waste ion exchange resin can be pyrolyzed into a porous carbon support, releasing highly dispersed metal oxides in situ. Hydrogen sulfide (H2S) waste gas can serve as a gaseous sulfur source, reacting with metal oxides in a gas-solid reaction to generate metal sulfides. The synergistic coupling of these two processes enables an integrated process of "solid waste disposal - waste gas resource recovery - efficient mercury removal." Therefore, this invention develops a metal sulfide preparation technology using multi-source hazardous waste as raw materials, featuring a simple process, environmental friendliness, and low cost. This technology can achieve high-value applications in flue gas mercury pollution control, possessing significant environmental, social, and engineering application value.

[0021] The beneficial effects of this invention are: 1) This invention provides a method for the synergistic resource utilization of multi-source hazardous waste, effectively solving the problems of waste ion exchange resin disposal and H2S waste gas pollution: using waste ion exchange resin as raw material, no additional carbon source or metal precursor is required, realizing the reduction and resource utilization of hazardous waste; using industrial H2S waste gas as sulfur source, no external sulfur reagent is required, converting toxic waste gas into high-value active sites, truly realizing waste treatment and turning waste into treasure, reducing environmental risks and raw material costs.

[0022] 2) This invention provides a preparation route for high-performance metal sulfide / carbon composite materials. The prepared material exhibits excellent performance in the removal of heavy metal mercury pollutants: relying on the spherical porous structure retained after the pyrolysis of waste ion exchange resin, the mass transfer efficiency of gaseous pollutants is improved; the active sites of metal sulfides are generated by in-situ gas-phase deposition of H2S, which is uniformly dispersed, not prone to agglomeration, and tightly bound to the carbon support, significantly improving the removal efficiency of Hg.0 Adsorption capacity and selectivity: The material combines the porous advantages of carbon supports with the strong chemisorption capacity of metal sulfides, exhibits excellent sulfur resistance, and can operate stably in complex sulfur-containing flue gas, avoiding adsorbent poisoning and deactivation.

[0023] 3) This invention provides a simple and efficient metal sulfide preparation process, which makes the process flow simple and highly feasible: it integrates the two-step process of pyrolysis reconstruction and vapor deposition, which is simple to operate, has controllable energy consumption, requires no complex equipment, and is suitable for industrial-scale production; the whole process has no secondary pollution and meets the requirements of green environmental protection and pollution reduction and carbon reduction.

[0024] 4) This invention provides an integrated technical solution for the synergistic treatment of multiple pollutants, resulting in significant application value: forming a "waste ion exchange resin disposal - H2S resource utilization - flue gas Hg" process. 0 The whole-chain technology of "removal" not only solves the environmental problems of industrial solid waste and waste gas, but also provides a low-cost and high-efficiency mercury removal solution, which has significant environmental, social and economic benefits. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method and application of the present invention; Figure 2 The images show physical representations of the waste ion exchange resin, metal oxide / carbon composite material, and metal sulfide / carbon composite material of the present invention. Figure 2 (a) is a photograph of waste Cu ion exchange resin. Figure 2 (b) is a physical image of the CuO / Cu2O / carbon composite product obtained by pyrolysis and reconstruction of waste Cu ion exchange resin at 600 °C. Figure 2 (c) is a physical image of the CuS / Cu2S / carbon composite product after in-situ deposition and transformation of CuO / Cu2O / carbon composite in H2S. Figure 3 The X-ray diffraction spectrum (XRD) of the CuO / Cu2O / carbon composite material and the CuS / Cu2S / carbon composite material of the present invention are shown below. Figure 4 The image shows the energy dispersive X-ray spectra (EDS) of the CuS / Cu2S / carbon composite material of this invention. Figure 5 This is a diagram showing the mercury removal efficiency of the present invention, wherein, Figure 5 (a) is a graph showing the mercury removal efficiency of Example 1 and Comparative Example 1. Figure 5 (b) is a mercury removal efficiency graph for Example 1 and Comparative Example 2. Figure 5(c) is a graph showing the mercury removal efficiency of Example 2 and Comparative Example 3; Figure 6 The image shows the XRD pattern of CuO / Cu2O / carbon composites, the waste ion exchange resin pyrolysis products at different pyrolysis temperatures in Comparative Example 1. Figure 7 The O2-TPD (Oxygen Temperature-Programmed Desorption) spectra of the CuO / Cu2O / carbon complex, a waste ion exchange resin pyrolysis product at different pyrolysis temperatures in Comparative Example 1, are shown. Figure 8 CO2-TPD spectra of CuO / Cu2O / carbon complexes, waste ion exchange resin pyrolysis products at different pyrolysis temperatures in Comparative Example 1. Figure 9 The graph shows the in-situ H2S conversion efficiency on the CuO / Cu2O / carbon composite, a product of waste ion exchange resin pyrolysis at different pyrolysis temperatures in Comparative Example 1. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments. The scope of protection of the present invention is not limited to the following embodiments. All equivalent transformations or improvements made based on the technical solutions of the present invention shall fall within the scope of protection of the present invention.

[0027] Specific embodiments and comparative examples of the present invention are as follows: Example 1:

[0028] This embodiment uses gaseous elemental mercury (Hg) from coal-fired flue gas. 0 With the removal as the target, Cu adsorption is employed. 2+ Waste strong acid cation exchange resin as raw material (Cu 2+ The load is 5 wt%), which comes from wastewater treatment of boiler softening water in the thermal power industry and H2S gas separated and enriched in the coal gasification industry for in-situ H2S conversion. The specific steps are as follows: Step S1) First, load Cu 2+ Waste ion exchange resin particles were recycled and pretreated by washing them three times with deionized water for 20 minutes each time, followed by drying at 80 °C for 8 hours to remove surface impurities, free water, and large particles, resulting in pretreated waste ion exchange resin particles, such as... Figure 2As shown in (a); then, pyrolysis component reconstruction was performed. 10 g of pretreated waste ion exchange resin particles were placed in a tubular furnace pyrolysis device for high-temperature pyrolysis reaction. The high-temperature pyrolysis reaction was carried out under the protection of a mixture of nitrogen and air. The nitrogen flow rate was 150 mL / min, the air flow rate was 50 mL / min, and the temperature was increased to 600 °C at a heating rate of 5 °C / min and held for 2 h. The CuO / Cu2O / carbon composite materials after pyrolysis reconstruction at three different temperatures were obtained. During the pyrolysis reaction, the organic framework of the pretreated waste ion exchange resin particles underwent high-temperature carbonization to form a porous carbon matrix. The Cu loaded in the pretreated waste ion exchange resin particles... 2+ A precursor oxidation reaction occurs, generating CuO / Cu2O nanoparticles in situ, while retaining the original spherical porous mass transfer structure of the pretreated waste ion exchange resin particles. After cooling to room temperature, a CuO / Cu2O / carbon composite material is obtained, such as... Figure 2 As shown in (b).

[0029] Step S2) Then, the CuO / Cu2O / carbon composite material is placed in a tubular vapor deposition apparatus. Industrial hydrogen sulfide (H2S) waste gas is recovered and mixed with nitrogen as a gaseous active sulfur source (volume fraction 30%). The mixture is then introduced into the tubular vapor deposition apparatus for in-situ chemical vapor deposition reaction. The total gas flow rate is 150 mL / min. The reaction temperature is controlled at 150℃, the volume fraction of hydrogen sulfide (H2S) in the industrial hydrogen sulfide (H2S) waste gas is 10%, and the reaction time is 2 h. This allows the hydrogen sulfide (H2S) to undergo an in-situ vapor deposition reaction with the CuO / Cu2O in the CuO / Cu2O / carbon composite material. The hydrogen sulfide (H2S) is directionally adsorbed onto the CuO / Cu2O / carbon composite material for surface reconstruction, and the CuO / Cu2O is directionally converted into CuS / Cu2S active sites. During the reaction, the spherical porous mass transfer structure of the CuO / Cu2O / carbon composite material is preserved. After the reaction was completed, nitrogen gas was continuously introduced to purge any remaining hydrogen sulfide (H2S) gas in the tubular vapor deposition apparatus for 30 minutes to prevent the accumulation of toxic gases. After cooling to room temperature, a CuS / Cu2S / carbon composite material was obtained, as shown below. Figure 2 As shown in (c).

[0030] Then, the characterization tests were performed as follows: The crystal phase structure and composition of CuO / Cu2O / carbon composite materials obtained by pyrolysis and reconstruction of waste ion exchange resin and CuS / Cu2S / carbon composite materials prepared by H2S chemical deposition were tested using X-ray diffraction (XRD). Figure 3As shown, the diffraction peaks of the CuO / Cu2O / carbon composite material perfectly match the standard card PDF#48-1548 for copper oxide CuO, with no diffraction peaks for carbon. This indicates that after pyrolysis and reconstruction, the metal ions on the waste ion exchange resin are completely converted into highly crystalline CuO, while the carbon skeleton exists as an amorphous graphite phase. The diffraction peaks of the CuS / Cu2S / carbon composite material match the standard card PDF#06-0464 for copper sulfide CuS. Among them, the diffraction peaks at θ at 27.1°, 27.66°, 29.26°, 31.74°, 32.84°, 47.9°, 52.72° and 59.3° correspond to the (100), (101), (102), (103), (006), (110), (108) and (116) crystal planes of CuS, respectively. This indicates that H2S is completely transformed in the CuO / Cu2O / carbon composite material, and after surface reconstruction, a highly crystalline CuS phase is formed.

[0031] The surface elemental distribution of CuS / Cu2S / carbon composite materials prepared by H2S chemical deposition of CuO / Cu2O / carbon composite materials obtained by pyrolysis at 600 ℃ was determined by energy-dispersive X-ray spectroscopy (EDS). Figure 4 As shown, the surface O content is low, and the Cu and S elements are highly overlapping in space and have high intensity, indicating that the waste ion exchange resin pyrolysis reconstruction coupled H2S in-situ conversion strategy provided by the present invention can effectively convert H2S into CuS / Cu2S rich in coordinated unsaturated sulfur sites on the surface O sites.

[0032] Mercury removal application: The CuS / Cu2S / carbon composite material prepared by H2S chemical deposition of the CuO / Cu2O / carbon composite material obtained by pyrolysis at 600 °C is preferred as the adsorbent and introduced into a simulated coal-fired flue gas system (flue gas composition: Hg) using a fixed-bed packing method. 0 Concentration 50 μg / m 3 The concentrations were: HCl 100 ppm, SO2 800 ppm, NO 400 ppm, O2 6%, CO2 12%, and N2 as the balance gas; the total gas flow rate was 1 L / min, and the adsorption dose was 10 mg. This simulated the actual flue gas conditions of a coal-fired power plant. The adsorption temperature was controlled at 80 ℃, and the system was run continuously for 60 min. The test results showed that... Figure 5 (a) and Figure 5 As shown in (b), Hg 0 The removal rate is consistently above 90%, the adsorbent shows no obvious poisoning or deactivation, the generated HgS has good thermal stability and no risk of secondary release, and it can be adapted to the complex composition environment of coal-fired flue gas.

[0033] Example 2:

[0034] This embodiment uses gaseous elemental mercury (Hg) from non-ferrous metal smelting flue gas. 0 With the removal as the target, Ni adsorption is employed. 2+ Waste strong acid cation exchange resin as raw material (Ni 2+ The loading rate was 7 wt%), and its source was nickel-containing wastewater treatment in the electroplating industry. The process involved in-situ H2S conversion using H2S gas separated and enriched during natural gas purification. The specific steps are as follows: Step S1) First, load Ni 2+ Waste ion exchange resin particles were recycled and pretreated by washing them three times with deionized water for 20 minutes each time, followed by drying at 80 °C for 8 hours to remove surface impurities, free water, and large particles, resulting in pretreated waste ion exchange resin particles. Then, pyrolysis reconstruction was performed. 10 g of the pretreated waste ion exchange resin particles were placed in a tubular furnace pyrolysis apparatus for high-temperature pyrolysis under a nitrogen and air mixture. The nitrogen flow rate was 150 mL / min, the air flow rate was 50 mL / min, and the temperature was increased to 600 °C at a rate of 5 °C / min and held for 2 hours, yielding a pyrolyzed NiO / carbon composite material. During the pyrolysis reaction, the organic framework of the pretreated waste ion exchange resin particles underwent high-temperature carbonization to form a porous carbon matrix. The NiO loaded in the pretreated waste ion exchange resin particles... 2+ A precursor oxidation reaction occurs, generating NiO nanoparticles in situ while retaining the original spherical porous mass transfer structure of the pretreated waste ion exchange resin particles. After cooling to room temperature, a NiO / carbon composite material is obtained.

[0035] Step S2) The NiO / carbon composite material is then placed in a tubular vapor deposition apparatus. Industrial hydrogen sulfide (H2S) waste gas is recovered and mixed with nitrogen as a gaseous active sulfur source (30% by volume). This mixture is then introduced into the tubular vapor deposition apparatus for in-situ chemical vapor deposition. The total gas flow rate is 150 mL / min. The reaction temperature is controlled at 150 °C, the volume fraction of H2S in the industrial H2S waste gas is 10%, and the reaction time is 2 h. This allows H2S to undergo an in-situ vapor deposition reaction with the Ni-O sites in the NiO / carbon composite material. H2S is directionally adsorbed onto the NiO / carbon composite material for surface reconstruction, converting NiO into Ni-S active sites. During the reaction, the spherical porous mass transfer structure of the metal oxide / carbon composite material is preserved. After the reaction, nitrogen is continuously introduced to purge the tubular vapor deposition apparatus for residual H2S gas for 30 min to avoid toxic gas residue. After cooling to room temperature, the Ni-S / carbon composite material is obtained.

[0036] Mercury removal application: The Ni-S / carbon composite material prepared above is used as an adsorbent and introduced into a simulated metallurgical flue gas system in a fixed-bed packing manner (flue gas composition: Hg). 0 Concentration 500 μg / m 3 SO2 concentration is 2000 mg / m³ 3 NO concentration is 500 mg / m³ 3 The concentrations were: O2 2%, CO2 8%, CO 8%, N2 as the balance gas, total gas flow rate 1 L / min, and adsorption dose 100 mg, simulating actual flue gas conditions in a smelter. The adsorption temperature was controlled at 80 ℃, and the system was run continuously for 60 min. The test results showed that... Figure 5 As shown in (c), Hg 0 The removal rate is stable at over 85%, the adsorbent shows no obvious poisoning or deactivation, the generated HgS has good thermal stability and no risk of secondary release, and it can be adapted to the high-sulfur complex composition environment of metallurgical flue gas.

[0037] Comparative Example 1: The difference between this comparative example and Example 1 is that in step S1, during the pyrolysis and reconstruction of the waste ion exchange resin, the temperature was raised to 500 ℃ and 700 ℃ respectively at a heating rate of 5 ℃ / min, and held for 2 h to carry out the high-temperature pyrolysis and reconstruction reaction, so as to obtain CuO / Cu2O / carbon composite materials after pyrolysis and reconstruction at two different temperatures. The remaining steps, process parameters and application conditions are the same as those in Example 1.

[0038] Characterization tests: X-ray diffraction (XRD) was used to test the crystal phase structure and composition of CuO / Cu2O / carbon composite materials obtained after pyrolysis and reconstruction of waste ion exchange resin at 500 ℃, 600 ℃, and 700 ℃. Figure 6 As shown, the diffraction peaks of the CuO / Cu2O / carbon composite material perfectly match those of the standard card PDF#48-1548 for copper oxide, with no diffraction peaks for carbon. This indicates that after pyrolysis and reconstruction, the metal ions on the waste ion exchange resin are completely converted into CuO / Cu2O, while the carbon skeleton exists as an amorphous graphite phase. At a pyrolysis temperature of 500 °C, CuO / Cu2O exhibits poor crystallinity, resulting in low diffraction peaks on the (111) crystal plane of the active phase. However, at an excessively high pyrolysis temperature of 700 °C, CuO / Cu2O becomes highly crystalline, reducing surface defects / vacancies, which is detrimental to the subsequent directional conversion of H2S.

[0039] The oxidation capacity of the CuO / Cu2O / carbon composite material obtained after pyrolysis and reconstruction of waste ion exchange resin was tested using O2-programmed temperature desorption O2-TPD. Figure 7As shown, the CuO / Cu2O / carbon composite materials obtained by pyrolysis reconstruction at three temperatures exhibit a mid-temperature O2 desorption peak at 300-400 °C, corresponding to chemisorbed active oxygen. Specifically, the O2 desorption peak of the CuO / Cu2O / carbon composite material obtained by pyrolysis at 500 °C is located at 357.1 °C, the O2 desorption peaks of the CuO / Cu2O / carbon composite material obtained by pyrolysis at 600 °C are located at 333.7 and 358.7 °C, and the O2 desorption peak of the CuO / Cu2O / carbon composite material obtained by pyrolysis at 700 °C is located at 346.5 °C. The CuO / Cu2O / carbon composite material obtained by pyrolysis at 600 °C exhibits a lower O2 desorption temperature and a stronger O2 desorption intensity, indicating that it has the strongest oxidation capacity and oxygen migration capacity, and a stronger adsorption capacity for H2S.

[0040] The surface alkaline site distribution and strength of CuO / Cu2O / carbon composite materials obtained after pyrolysis and reconstruction of waste ion exchange resin were tested using CO2 temperature-programmed desorption CO2-TPD. Figure 8 As shown, the CuO / Cu2O / carbon composite materials obtained by pyrolysis reconstruction at three temperatures exhibit mesophilic CO2 desorption peaks at 300-400 ℃, corresponding to moderate-intensity alkaline sites. Specifically, the CO2 desorption peaks of the CuO / Cu2O / carbon composite material obtained by pyrolysis at 500 ℃ are located at 79.2 and 356.3 ℃, the CO2 desorption peaks of the CuO / Cu2O / carbon composite material obtained by pyrolysis at 600 ℃ are located at 83.2 and 227.4 ℃, and the CO2 desorption peaks of the CuO / Cu2O / carbon composite material obtained by pyrolysis at 700 ℃ are located at 82.4 and 358.8 ℃. The CuO / Cu2O / carbon composite material obtained by pyrolysis at 600 ℃ has a lower CO2 desorption temperature and a stronger CO2 desorption intensity, indicating that the strength and abundance of its surface alkaline sites are better than those of the CuO / Cu2O / carbon composite materials obtained by pyrolysis at 500 and 700 ℃. According to the principle of acid-base reaction, the stronger the alkalinity, the stronger the adsorption and conversion capacity of H2S.

[0041] Gas chromatography-mass spectrometry (GC-MS) was used to analyze the H2S concentration at the outlet of the tubular vapor deposition apparatus in step S2). The H2S conversion efficiency on the CuO / Cu2O / carbon composite material after pyrolysis and reconstruction at different temperatures was calculated using the formula: 100 × (H2S inlet concentration - H2S outlet concentration) / H2S inlet concentration = H2S conversion rate. Figure 9As shown, the H2S conversion rate of the CuO / Cu2O / carbon composite material obtained by pyrolysis at 600 °C is as high as 99.8%, while that of the CuO / Cu2O / carbon composite materials obtained by pyrolysis at 500 °C and 700 °C is 75.6% and 88.5%, respectively. This indicates that pyrolysis of waste ion exchange resin at 600 °C can yield the most suitable CuO / Cu2O / carbon composite material for in-situ H2S conversion, which is consistent with the characterization analysis above.

[0042] Mercury removal test results: such as Figure 5 As shown in (a), the CuO / Cu2O / carbon composite material obtained by pyrolysis at 500 °C, after in-situ deposition of H2S, has an initial Hg 0 The removal rate was only 78.5%, and after 60 minutes of continuous operation, the removal rate dropped to 45.2%. The CuO / Cu2O / carbon composite material obtained by pyrolysis at 700 ℃, after in-situ deposition of H2S, initially showed a low Hg content. 0 The removal rate was only 85.2%, and after 60 minutes of continuous operation, it dropped to 60.5%. The main reason is that the excessively low pyrolysis temperature resulted in insufficient crystallinity and content of CuO / Cu2O, poor surface oxygen activity, and few surface alkaline sites, leading to insufficient H2S conversion efficiency and low CuS / Cu2S conversion content, resulting in poor mercury removal performance. Conversely, the excessively high pyrolysis temperature led to high crystallinity of CuO / Cu2O, poor surface oxygen migration, and decreased alkalinity due to surface alkali volatilization. This resulted in even less coordinated unsaturated sulfur on the CuS / Cu2S surface after in-situ H2S deposition, further contributing to poor mercury removal performance.

[0043] Comparative Example 2: The difference between this comparative example and Example 1 is that step S2) (in-situ preparation of metal sulfide / carbon composite material by H2S chemical deposition) is omitted, and the CuO / Cu2O / carbon composite material obtained in step S1) is directly used as an adsorbent in simulated coal-fired flue gas Hg 0 The remaining steps, process parameters, and application conditions are the same as in Example 1.

[0044] Mercury removal test results: such as Figure 5 As shown in (b), the initial Hg 0 The removal rate was only 45.3%, and after 60 minutes of continuous operation, the removal rate dropped to below 20%. The main reason is that CuO / Cu2O has a negative effect on Hg removal. 0 Its adsorption capacity is weak, and it is easily poisoned by SO2 in coal-fired flue gas, leading to the failure of active sites.

[0045] Comparative Example 3: The difference between this comparative example and Example 2 is that in step S2), commercial sulfur powder is used as the sulfur source (to replace H2S waste gas), while the remaining steps, process parameters and application conditions are the same as in Example 2.

[0046] Test results: such as Figure 5 As shown in (c), the initial Hg 0 The removal rate was 82.5%, but after 60 minutes of continuous operation, the removal rate dropped to below 65%. Furthermore, the sulfur powder was not evenly dispersed, which led to the agglomeration of NiS active sites, reduced mass transfer efficiency, and increased raw material costs. The resource utilization of H2S waste gas was not achieved, and the goal of treating waste with waste could not be achieved.

[0047] In summary, this invention, through the synergistic effect of pyrolysis reconstruction and H2S chemical deposition steps, uses two different types of industrial waste ion exchange resins as raw materials to prepare high-performance metal sulfide / carbon composite materials suitable for coal-fired flue gas and metallurgical flue gas, respectively. This achieves the synergistic resource utilization of multi-source hazardous waste and the reduction of Hg in flue gas under different operating conditions. 0 Highly efficient removal has significant advantages over existing technologies, and the reasonable control of various process parameters (such as pyrolysis temperature, H2S concentration, etc.) is the key to ensuring material performance and application effect.

[0048] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A method for preparing metal sulfide / carbon composite materials based on multi-waste pyrolysis reconstruction-vapor phase deposition, characterized in that, include: Step S1) The waste ion exchange resin particles after wastewater treatment are recovered and pretreated. The waste ion exchange resin particles are Cu adsorbents. 2+ or Ni 2+ The waste strong acid cation exchange resin is then carbonized and oxidized through pyrolysis component reconstruction to obtain metal oxide / carbon composite materials, namely CuO / Cu2O / carbon composite materials or NiO / carbon composite materials, without the need to add additional carbon source and metal precursor; Step S2) The metal oxide / carbon composite material is placed in a tubular vapor deposition apparatus. The industrial hydrogen sulfide (H2S) waste gas after gas treatment is recovered and used as a gaseous active sulfur source. Then, it is introduced into the tubular vapor deposition apparatus to carry out a chemical in-situ vapor deposition reaction. The surface active phase is reconstructed by directional adsorption onto the metal oxide / carbon composite material to obtain a metal sulfide / carbon composite material, namely CuS / Cu2S / carbon composite material or Ni-S / carbon composite material. In step S1), when pretreating the waste ion exchange resin particles, the waste ion exchange resin particles are washed with water and dried in sequence to obtain pretreated waste ion exchange resin particles. Then, the pyrolysis components are reconstructed. The pretreated waste ion exchange resin particles are placed in a tubular furnace pyrolysis device for high-temperature pyrolysis reaction. During the reaction, the organic framework of the pretreated waste ion exchange resin particles is carbonized to form a porous carbon matrix. The metal ions loaded in the pretreated waste ion exchange resin particles undergo oxidation reaction to generate metal oxide nanoparticles in situ, while retaining the original spherical porous mass transfer structure of the pretreated waste ion exchange resin particles. After cooling to room temperature, metal oxide / carbon composite material is obtained. In step S1), a high-temperature pyrolysis reaction is carried out under an inert or oxidizing atmosphere. The total flow rate of the inert or oxidizing atmosphere is 50-200 mL / min. The heating rate of the high-temperature pyrolysis reaction is 2-10 °C / min, the temperature is 600 °C, and the holding time after reaching the preset target temperature is 1-4 h. In step S2), when the industrial hydrogen sulfide (H2S) waste gas undergoes in-situ chemical vapor deposition, the reaction temperature is controlled at 50-300 °C, the volume fraction of hydrogen sulfide (H2S) in the industrial hydrogen sulfide (H2S) waste gas is 5%-50%, and the reaction time is 0.5-3 h. This allows the hydrogen sulfide (H2S) to undergo in-situ vapor deposition with the metal oxide in the metal oxide / carbon composite material, directionally converting the metal oxide into active sites for metal sulfides. During the reaction, the spherical porous mass transfer structure of the metal oxide / carbon composite material is preserved. After cooling to room temperature, the metal sulfide / carbon composite material is finally obtained.

2. The method for preparing metal sulfide / carbon composite materials based on multi-waste pyrolysis reconstruction-vapor phase deposition according to claim 1, characterized in that: In step S1), the waste ion exchange resin particles are cation exchange resins loaded with metal ions, and metal oxides are generated in situ after the metal ions undergo an oxidation reaction.

3. The method for preparing metal sulfide / carbon composite materials based on multi-waste pyrolysis reconstruction-vapor phase deposition according to claim 1, characterized in that: In step S1), during pretreatment, deionized water is used for washing; the drying temperature does not exceed 100 ℃.

4. The method for preparing metal sulfide / carbon composite materials based on multi-waste pyrolysis reconstruction-vapor phase deposition according to claim 1, characterized in that: In step S2), during the in-situ chemical vapor deposition reaction of industrial hydrogen sulfide (H2S) waste gas, an inert carrier gas is simultaneously introduced at a total flow rate of 200-500 mL / min. After the reaction is completed, the inert carrier gas is continued to purge the residual hydrogen sulfide (H2S) gas in the tube vapor deposition device for 10-30 min.

5. A metal sulfide / carbon composite material based on multi-waste pyrolysis reconstruction-vapor phase deposition, characterized in that: The metal sulfide / carbon composite material is prepared by any one of the methods described in claims 1-4.

6. The application of the metal sulfide / carbon composite material based on multi-waste pyrolysis reconstruction-vapor phase deposition according to claim 5, characterized in that: The applications include using it as an adsorbent to immobilize gaseous elemental mercury (Hg) in source flue gas. 0 Adsorption and removal.

7. The application method of metal sulfide / carbon composite material based on multi-waste pyrolysis reconstruction-vapor phase deposition according to claim 5, characterized in that: The application method involves placing a metal sulfide / carbon composite material in a container containing gaseous elemental mercury (Hg) using either a spray or fixed-bed loading method. 0 In stationary source flue gas, the adsorption temperature is controlled at 50~150 ℃ to allow gaseous elemental mercury (Hg) to be absorbed. 0 A chemical adsorption reaction occurs between the mercury sulfide active sites on the surface of the metal sulfide / carbon composite material, generating a stable mercury sulfide (HgS) compound, thereby immobilizing gaseous elemental mercury (Hg) in the source flue gas. 0 The efficient removal and permanent solidification of mercury in exhaust gas are used to control mercury pollution.

Images