Fe3O4-based TiS2 / ZnS double-layer loaded magnetic demercuration catalyst and preparation method thereof

Abstract

The invention provides a Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst. The Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst comprises a Fe3O4 magnetic core, a middle TiS2 layer and an outer ZnS layer which are sequentially distributed, the particle size of the Fe3O4 magnetic core is 50 to 100 nm, and the saturation magnetization is 100 to 110 emu / g; the thickness of the TiS2 layer is 1 to 3 nm; and the thickness of the ZnS layer is 1-3 nm. By accurately regulating and controlling the iron salt proportion, the reaction temperature, the calcining condition and the adding amount of the dispersing agent, the magnetic composite material can realize performance balance between efficient mercury removal and strong sulfur resistance, and meanwhile, the structural stability and the magnetic separation efficiency are ensured; the Fe3O4-based coated TiS2 / ZnS double-layer loaded magnetic demercuration catalyst solves the problems of poor sulfur resistance, unstable structure, limited magnetic performance and the like of a single-layer TiS2 catalyst through functional layering design and interface optimization, is particularly suitable for a demercuration scene of natural gas containing H2S, and has the advantages of high efficiency, long service life and easiness in recovery.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic materials, and particularly relates to a Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst and a preparation method thereof. Background Art

[0002] As an important clean energy source, natural gas often contains trace amounts of mercury (Hg) during its application process. Mercury exists in the elemental state (Hg 0 ) or ionic state (Hg 2+ ), and has extremely strong toxicity and persistent environmental hazards. It will not only cause corrosion and poisoning of downstream equipment, but also pollute the atmosphere and water bodies through combustion or leakage. To meet the requirements of environmental protection regulations and process safety, natural gas mercury removal technology has become a key link.

[0003] The existing technologies mainly include adsorption method, absorption method, membrane separation method, biological method and catalytic oxidation method. Among them, the adsorption method relies on porous materials (such as activated carbon, zinc oxide-based composites) to physically or chemically adsorb mercury. Although it has simple operation and no secondary pollution, its adsorption capacity is limited, it is easily challenged by low-concentration mercury (ppb level), and the adsorbent needs to be replaced frequently, resulting in poor economy; the absorption method reacts mercury with alkaline solution or organic solvent to form precipitates. Although it has high efficiency, it will generate mercury-containing wastewater and may corrode equipment, and the cost of secondary treatment is high; the membrane separation method uses a semi-permeable membrane to intercept mercury ions or elemental mercury, but the membrane is easily polluted by mercury, resulting in performance degradation, and its ability to tolerate complex gas components (such as hydrogen sulfide) is weak, making it difficult to be applied on a large scale; the biological method relies on microorganisms (such as sulfate-reducing bacteria) to reduce mercury to mercury sulfide precipitate, but its reaction conditions are harsh (anaerobic environment is required), the efficiency is significantly affected by pH and temperature fluctuations, and it is only suitable for the treatment of low-concentration mercury; the catalytic oxidation method oxidizes gaseous mercury to Hg 2+ and then combines with an absorbent for removal, but the catalyst is easily deactivated, and the energy consumption and maintenance cost are relatively high.

[0004] Therefore, it is urgent to develop a natural gas mercury removal material with high efficiency, low cost, environmental friendliness and adaptability to complex working conditions to solve the bottleneck of the existing technology and promote the development of clean utilization of natural gas. Although magnetic materials have the advantage of recyclability as mercury removal catalysts, their defects such as thermal stability, catalytic selectivity and magnetic separation efficiency limit their wide application in industrial scenarios. Magnetic materials are prone to sintering, structural collapse or magnetic loss at high temperatures, resulting in catalyst deactivation. Acidic components such as H2S and CO2 in natural gas may corrode the surface of the magnetic carrier, weakening its mechanical strength and magnetic properties.

[0005] In view of this, it is necessary to improve the magnetic materials in the existing technology to solve the above problems. Summary of the Invention

[0006] The object of the present invention is to disclose a magnetic material with strong sulfur resistance and stable structure, which has high efficiency and easy recovery characteristics during the process of mercury removal from natural gas. By means of double-layer loading, an optimal balance is achieved between the high-efficiency mercury removal and strong sulfur resistance of this magnetic material.

[0007] To achieve the above object, the present invention provides a Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst, which comprises a Fe3O4 magnetic core, an intermediate TiS2 layer and an outer ZnS layer distributed in sequence; the particle size of the Fe3O4 magnetic core is 50–100 nm, and the saturation magnetization intensity is 100–110 emu / g; the thickness of the TiS2 layer is 1–3 nm; the thickness of the ZnS layer is 1–3 nm.

[0008] To achieve the above object, the present invention also provides a preparation method of a Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst, which comprises the following steps:

[0009] Step 1: Weigh a certain amount of FeCl3·6H2O and FeCl2·4H2O according to the molar ratio of 1:1-1.5:1, dissolve them in deionized water, slowly add the FeCl2 solution to the FeCl3 solution, adjust the pH value of the solution to 8-11, then let it stand for a period of time, heat the solution to 70-90 °C and keep it warm for 5-7 h;

[0010] Step 2: Separate the particles by a centrifuge and wash them with deionized water until neutral.

[0011] Step 3: Vacuum-dry the particles obtained in Step 2 at 60 °C to obtain the Fe3O4 magnetic core for standby.

[0012] Step 4: Weigh a certain amount of TiOSO4 and Na2S according to the molar concentration ratio of 1:1.5-1:2, and add them to the Fe3O4 magnetic core suspension prepared by dissolving in deionized water in sequence to obtain a Fe3O4-based TiS2 precursor, and dry it for standby.

[0013] Step 5: Weigh a certain amount of Zn(NO3)2 and Na2S according to the molar concentration ratio of 1:1.5-1:2, and add them to the Fe3O4-based TiS2 precursor suspension prepared by dissolving in deionized water in sequence, and add a 1-2 wt% PVP (polyvinylpyrrolidone) solution to react to obtain a Fe3O4-based TiS2 / ZnS precursor, and dry it for standby.

[0014] Step 6: Calcinate the dried Fe3O4-based TiS2 / ZnS precursor obtained in Step 5 to prepare a Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst. The calcination temperature is 450-550 °C, the heating rate is 5 °C / min, calcine for 3 h and keep it warm for 1 h.

[0015] In some embodiments, the operating conditions of the centrifuge in Step 2 are a rotation speed of 3800 - 4500 rpm and a centrifugation time of 10 - 15 min.

[0016] In some embodiments, the reaction conditions in Step 4 are a reaction temperature of 60 - 70 °C and a reaction time of 2 - 2.5 h.

[0017] In some embodiments, the reaction conditions in Step 5 are a reaction temperature of 60 - 70 °C and a reaction time of 2 - 2.5 h.

[0018] In some embodiments, in Step 1, the preferred molar ratio of FeCl3·6H2O to FeCl2·4H2O is 1.2:1, the pH value is 10, and the reaction is carried out at 80 °C for 6 h.

[0019] In some embodiments, in Step 4, the preferred reaction temperature is 60 °C and the preferred reaction time is 2 h.

[0020] In some embodiments, in Step 5, the preferred reaction temperature is 70 °C and the preferred reaction time is 2 h.

[0021] In some embodiments, in Step 6, nitrogen is introduced for protection at a flow rate of 50 ml / min.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: By precisely regulating the iron salt ratio, reaction temperature, calcination conditions, and dispersant addition amount, it is possible to achieve a performance balance between the high-efficiency mercury removal and strong sulfur resistance of the magnetic composite material, while ensuring structural stability and magnetic separation efficiency; The Fe3O4-based coated TiS2 / ZnS double-layer supported magnetic mercury removal catalyst, through functional hierarchical design and interface optimization, solves the problems of poor sulfur resistance, unstable structure, and limited magnetic properties of the single-layer TiS2 catalyst, and is especially suitable for the mercury removal scenario of natural gas containing H2S, with the advantages of high efficiency, long life, and easy recovery. Specific Embodiments

[0023] The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, it should be noted that these embodiments do not limit the present invention, and any equivalent transformation or substitution in terms of function, method, or structure made by those of ordinary skill in the art according to these embodiments shall fall within the protection scope of the present invention.

[0024] Example 1

[0025] A Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst, comprising a sequentially distributed Fe3O4 magnetic core, an intermediate TiS2 layer, and an outer ZnS layer; the Fe3O4 magnetic core has a particle size of 50–100 nm and a saturation magnetization intensity of 100–110 emu / g; the TiS2 layer has a thickness of 1–3 nm; the ZnS layer has a thickness of 1–3 nm.

[0026] Example 2

[0027] A preparation method of a Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst, comprising the following steps:

[0028] Step 1: Weigh 10 mmol of FeCl3·6H2O and FeCl2·4H2O each according to a molar ratio of 1:1, and dissolve them in 50 ml of deionized water respectively. Slowly add the FeCl2 solution to the FeCl3 solution, and dropwise add ammonia water under stirring to adjust the pH value to 8. Then transfer the mixed solution to the first autoclave and carry out a hydrothermal reaction at 70 °C for 5 h.

[0029] Step 2: After the reaction is completed, cool to room temperature, and perform centrifugal separation. The working conditions of the centrifuge are a rotation speed of 3800 rpm and a centrifugation time of 10 min, and wash the precipitate with deionized water until it is neutral.

[0030] Step 3: Dry the particles in step 2 in an oven at 60 °C for 12 h to obtain the Fe3O4 magnetic core.

[0031] Step 4: Prepare 50 mL of a 0.5 mol / L TiOSO4 solution and 50 mL of a 1.0 mol / L Na2S solution. Disperse the prepared Fe3O4 magnetic core in 30 ml of deionized water to form a suspension. Under stirring, slowly add the TiOSO4 solution to the Fe3O4 suspension, and then dropwise add the Na2S solution. Control the reaction temperature at 70 °C and continuously stir for 2 h. After the reaction is completed, perform centrifugal separation and wash with deionized water until it is neutral, and dry at 60 °C for 6 h to obtain the Fe3O4-based TiS2 precursor.

[0032] Step 5: Prepare 50 mL of 0.5 mol / L Zn(NO3)2 solution and 50 mL of 1.0 mol / L Na2S solution. Disperse the Fe3O4-based TiS2 precursor in 30 mL of deionized water to form a suspension. Under stirring, slowly add the Zn(NO3)2 solution to the Fe3O4-based TiS2 suspension, then dropwise add the Na2S solution, and simultaneously add 1 wt% PVP (polyvinylpyrrolidone). Maintain the reaction temperature at 60 °C and stir for 2 h. After the reaction is completed, perform centrifugal separation, wash with deionized water until neutral, and dry at 60 °C for 6 h to obtain the Fe3O4-based TiS2 / ZnS precursor.

[0033] Step 6: Place the Fe3O4-based TiS2 / ZnS precursor in a tubular furnace. Under nitrogen protection, heat it to 450 °C at a heating rate of 5 °C / min, and calcine at this temperature for 3 h and hold for 1 h. After the calcination is completed, cool it to room temperature with the furnace to obtain the final Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst.

[0034] Example 3

[0035] A preparation method of an Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst, comprising the following steps:

[0036] Step 1: Weigh 12 mmol of FeCl3·6H2O and 10 mmol of FeCl2·4H2O according to a molar ratio of 1.2:1, and dissolve them in 50 ml of deionized water respectively. Slowly add the FeCl2 solution to the FeCl3 solution, dropwise add ammonia water under stirring to adjust the pH value to 10, then transfer the mixed solution to the first autoclave and carry out a hydrothermal reaction at 80 °C for 6 h.

[0037] Step 2: After the reaction is completed, cool it to room temperature, perform centrifugal separation, the working conditions of the centrifuge are a rotation speed of 4000 rpm and a centrifugation time of 10 min, and wash the precipitate with deionized water until neutral.

[0038] Step 3: Dry the particles in step 2 in an oven at 60 °C for 12 h to obtain the Fe3O4 magnetic core.

[0039] Step 4: Prepare 50 mL of 0.5 mol / L TiOSO4 solution and 50 mL of 1.0 mol / L Na2S solution. Disperse the prepared Fe3O4 magnetic core in 30 mL of deionized water to form a suspension. Under stirring, slowly add the TiOSO4 solution to the Fe3O4 suspension, and then dropwise add the Na2S solution. Control the reaction temperature at 60 °C and continuously stir for 2 h. After the reaction is completed, perform centrifugal separation, and wash with deionized water until neutral. Dry at 60 °C for 6 h to obtain the Fe3O4-based TiS2 precursor.

[0040] Step 5: Prepare 50 mL of 0.5 mol / L Zn(NO3)2 solution and 50 mL of 1.0 mol / L Na2S solution. Disperse the Fe3O4-based TiS2 precursor in 30 mL of deionized water to form a suspension. Under stirring, slowly add the Zn(NO3)2 solution to the Fe3O4-based TiS2 suspension, and then dropwise add the Na2S solution. At the same time, add 2 wt% PVP (polyvinylpyrrolidone). Maintain the reaction temperature at 70 °C and stir for 2 h. After the reaction is completed, perform centrifugal separation, wash with deionized water until neutral, and dry at 60 °C for 6 h to obtain the Fe3O4-based TiS2 / ZnS precursor.

[0041] Step 6: Place the Fe3O4-based TiS2 / ZnS precursor in a tubular furnace. Under nitrogen protection, heat it to 500 °C at a heating rate of 5 °C / min, and calcine at this temperature for 3 h and keep the temperature for 1 h. After the calcination is completed, cool it to room temperature with the furnace to obtain the final Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst.

[0042] Example 4

[0043] A preparation method of an Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst, comprising the following steps:

[0044] Step 1: Weigh 15 mmol of FeCl3·6H2O and 10 mmol of FeCl2·4H2O according to a molar ratio of 1.5:1, and dissolve them in 50 mL of deionized water respectively. Slowly add the FeCl2 solution to the FeCl3 solution, and dropwise add ammonia water under stirring to adjust the pH value to 11. Then transfer the mixed solution to the first reaction kettle and carry out a hydrothermal reaction at 90 °C for 7 h.

[0045] Step 2: After the reaction is completed, cool it to room temperature, perform centrifugal separation, the working conditions of the centrifuge are a rotation speed of 4000 rpm and a centrifugation time of 10 min, and wash the precipitate with deionized water until neutral.

[0046] Step 3: Dry the particles in step 2 in an oven at 60 °C for 12 h to obtain Fe3O4 magnetic cores.

[0047] Step 4: Prepare 50 mL of 0.5 mol / L TiOSO4 solution and 50 mL of 0.75 mol / L Na2S solution. Disperse the prepared Fe3O4 magnetic cores in 30 mL of deionized water to form a suspension. Under stirring, slowly add the TiOSO4 solution to the Fe3O4 suspension, and then dropwise add the Na2S solution. Control the reaction temperature at 60 °C and continuously stir for 2 h. After the reaction, perform centrifugal separation and wash with deionized water until neutral, and dry at 60 °C for 6 h to obtain the Fe3O4-based TiS2 precursor.

[0048] Step 5: Prepare 50 mL of 0.5 mol / L Zn(NO3)2 solution and 50 mL of 0.75 mol / L Na2S solution. Disperse the Fe3O4-based TiS2 precursor in 30 mL of deionized water to form a suspension. Under stirring, slowly add the Zn(NO3)2 solution to the Fe3O4-based TiS2 suspension, and then dropwise add the Na2S solution. At the same time, add 1.5 wt% PVP (polyvinylpyrrolidone). Maintain the reaction temperature at 70 °C and stir for 2 h. After the reaction is completed, perform centrifugal separation, wash with deionized water until neutral, and dry at 60 °C for 6 h to obtain the Fe3O4-based TiS2 / ZnS precursor.

[0049] Step 6: Place the Fe3O4-based TiS2 / ZnS precursor in a tubular furnace. Under nitrogen protection, heat it to 550 °C at a heating rate of 5 °C / min and calcine at this temperature for 3 h, and keep the temperature for 1 h. After the calcination, cool it to room temperature with the furnace to obtain the final Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst.

[0050] Example 5

[0051] A preparation method of an Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst includes the following steps:

[0052] Step 1: Weigh 10 mmol of FeCl3·6H2O and FeCl2·4H2O each according to a molar ratio of 1:1, and dissolve them in 50 mL of deionized water respectively. Slowly add the FeCl2 solution to the FeCl3 solution, and dropwise add ammonia water under stirring to adjust the pH value to 9. Then transfer the mixed solution to the first reaction kettle and carry out a hydrothermal reaction at 70 °C for 5 h.

[0053] Step 2: After the reaction, cool it to room temperature, perform centrifugal separation, the working conditions of the centrifuge are a rotation speed of 4500 rpm and a centrifugation time of 10 min, and wash the precipitate with deionized water until neutral.

[0054] Step 3: Dry the particles in step 2 in an oven at 60 °C for 12 h to obtain Fe3O4 magnetic cores.

[0055] Step 4: Prepare 50 mL of 0.5 mol / L TiOSO4 solution and 50 mL of 1.0 mol / L Na2S solution. Disperse the prepared Fe3O4 magnetic cores in 30 mL of deionized water to form a suspension. Under stirring, slowly add the TiOSO4 solution to the Fe3O4 suspension, and then gradually add the Na2S solution drop by drop. Control the reaction temperature at 65 °C and continuously stir for 2.5 h. After the reaction is completed, perform centrifugal separation and wash with deionized water until neutral, and then dry at 60 °C for 6 h to obtain the Fe3O4-based TiS2 precursor.

[0056] Step 5: Prepare 50 mL of 0.5 mol / L Zn(NO3)2 solution and 50 mL of 1.0 mol / L Na2S solution. Disperse the Fe3O4-based TiS2 precursor in 30 mL of deionized water to form a suspension. Under stirring, slowly add the Zn(NO3)2 solution to the Fe3O4-based TiS2 suspension, and then gradually add the Na2S solution drop by drop. At the same time, add 1 wt% PVP (polyvinylpyrrolidone). Maintain the reaction temperature at 70 °C and stir for 2.5 h. After the reaction is completed, perform centrifugal separation, wash with deionized water until neutral, and then dry at 60 °C for 6 h to obtain the Fe3O4-based TiS2 / ZnS precursor.

[0057] Step 6: Place the Fe3O4-based TiS2 / ZnS precursor in a tube furnace. Under nitrogen protection, heat it to 550 °C at a heating rate of 5 °C / min, and calcine at this temperature for 3 h and hold for 1 h. After the calcination is completed, cool it to room temperature with the furnace to obtain the final Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst.

[0058] Performance test

[0059] (1) Saturation magnetization intensity: Measured by a vibrating sample magnetometer;

[0060] (2) Mercury removal efficiency: Hg 0 Removal rate (ultraviolet light assisted);

[0061] (3) Sulfur resistance test: Simulate the H2S environment aging experiment.

[0062] Control Example 1

[0063] A preparation method of an Fe3O4-based TiS2 / magnetic mercury removal catalyst, comprising the following steps:

[0064] Step 1: Weigh 12 mmol of FeCl3·6H2O and 10 mmol of FeCl2·4H2O respectively according to the molar ratio of 1.2:1, and dissolve them in 50 ml of deionized water respectively. Slowly add the FeCl2 solution to the FeCl3 solution, and dropwise add ammonia water under stirring to adjust the pH value to 10. Then transfer the mixed solution to the first autoclave and carry out hydrothermal reaction at 80 °C for 6 h.

[0065] Step 2: After the reaction is completed, cool it to room temperature, and carry out centrifugal separation. The working conditions of the centrifuge are a rotation speed of 4000 rpm and a centrifugation time of 10 min, and wash the precipitate with deionized water until it is neutral.

[0066] Step 3: Dry the particles in step 2 in an oven at 60 °C for 12 h to obtain Fe3O4 magnetic cores.

[0067] Step 4: Prepare 50 mL of 0.5 mol / L TiOSO4 solution and 50 mL of 1.0 mol / L Na2S solution. Disperse the prepared Fe3O4 magnetic cores in 30 ml of deionized water to form a suspension. Under stirring, slowly add the TiOSO4 solution to the Fe3O4 suspension, and then dropwise add the Na2S solution. Control the reaction temperature at 60 °C and continuously stir for 2 h. After the reaction is completed, carry out centrifugal separation and wash it with deionized water until it is neutral, and dry it at 60 °C for 6 h to obtain the Fe3O4-based TiS2 precursor.

[0068] Step 5: Place the Fe3O4-based TiS2 precursor in a tube furnace. Under nitrogen protection, heat it to 500 °C at a heating rate of 5 °C / min, and calcine it at this temperature for 3 h and keep it warm for 1 h. After the calcination is completed, cool it to room temperature with the furnace to obtain the final Fe3O4-based TiS2 magnetic mercury removal catalyst.

[0069] Table 1 Comparison of Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalysts in each example

[0070] Example Iron salt ratio <![CDATA[Temperature of TiS2 layer]]> ZnS layer temperature Calcination temperature PVP addition amount Saturation magnetization intensity Hg0 removal rate 2 1:1 70℃ 60℃ 450℃ 1wt% 107 95.6％ 3 1.2:1 60℃ 70℃ 500℃ 2wt% 110 98.5％ 4 1.5:1 60℃ 70℃ 550℃ 1.5wt% 105 96％ 5 1:1 65℃ 70℃ 550℃ 1wt% 103 97.2％

[0071] As can be seen from the above text, when the proportion of iron salts (i.e., Fe 3+ and Fe 2+ ) increases, Fe 3+ effectively improves the saturation magnetization intensity. After the reaction temperature of the ZnS layer increases, it can promote the densification of the ZnS layer, reduce the porosity, and improve the mercury removal rate.

[0072] Table 2 Comparison of Fe3O4-based TiS2 single-layer magnetic mercury removal catalyst and Fe3O4-based TiS2 / ZnS double-layer loaded magnetic mercury removal catalyst

[0073] Parameter <![CDATA[Single-layer TiS2 magnetic catalyst]]> <![CDATA[Double-layer TiS2 / ZnS magnetic catalyst]]> Increase amplitude (%) <![CDATA[Hg 0 Removal rate (ultraviolet light)]]> 85–90％ ≥95％ +10–15％ <![CDATA[H2S resistance (H2S concentration: 10 ppm)]]> Deactivation in 10 minutes Stable for > 1 hour +∞ Magnetic separation efficiency after 50 cycles ≤80％ >98％ +25％ Saturation magnetization intensity 90–100 emu / g 100–110 emu / g +10–20％

[0074] As can be seen from the above, the double-layer structure has more advantages than the single-layer structure. As the outermost layer, the ZnS layer can effectively prevent the TiS2 layer from being affected, and the sulfur resistance is significantly improved; the ZnS layer can assist Hg 0 adsorption under lightless conditions. Therefore, the double-layer structure has a higher mercury removal rate under ultraviolet light assistance. In addition, the ZnS layer can protect the magnetic core and reduce the loss of the Fe3O4 magnetic core in high-temperature or oxidation environments, and the saturation magnetization intensity is increased by 10–20%. The double-layer structure can be quickly recovered by a magnetic field, reducing the catalyst loss rate.

[0075] The series of detailed descriptions listed above are only specific descriptions of the feasible implementation modes of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent implementation modes or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

[0076] In addition, it should be understood that although this specification is described according to implementation modes, not every implementation mode only includes an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst, characterized in that, It includes a sequentially distributed Fe3O4 magnetic core, an intermediate TiS2 layer, and an outer ZnS layer; The particle size of the Fe3O4 magnetic core is 50–100 nm, and the saturation magnetization intensity is 100–110 emu / g; The thickness of the TiS2 layer is 1–3 nm; The thickness of the ZnS layer is 1–3 nm.

2. A preparation method of a Fe3O4-based TiS2 / ZnS bilayer-loaded magnetic mercury removal catalyst as described in claim 1, characterized in that, It includes the following steps: Step 1: Weigh a certain amount of FeCl3·6H2O and FeCl2·4H2O according to the molar ratio of 1:1 - 1.5:1 and dissolve them in deionized water. Slowly add the FeCl2 solution to the FeCl3 solution, adjust the pH value of the solution to 8 - 11, and then let it stand for a period of time. Heat the solution to 70 - 90 °C and keep it warm for 5 - 7 h; Step 2: Separate the particles by a centrifuge and wash them with deionized water until neutral; Step 3: Vacuum-dry the particles in Step 2 at 60 °C to obtain the Fe3O4 magnetic core for standby; Step 4: Weigh a certain amount of TiOSO4 and Na2S according to the molar concentration ratio of 1:1.5 - 1:2 and add them successively to the Fe3O4 magnetic core suspension prepared by dissolving in deionized water to obtain the Fe3O4-based TiS2 precursor. After drying, it is for standby; Step 5: Weigh a certain amount of Zn(NO3)2 and Na2S according to the molar concentration ratio of 1:1.5 - 1:2 and add them successively to the Fe3O4-based TiS2 precursor suspension prepared by dissolving in deionized water, and add a 1 - 2 wt% PVP (polyvinylpyrrolidone) solution to react to obtain the Fe3O4-based TiS2 / ZnS precursor. After drying, it is for standby; Step 6: Calcinate the dried Fe3O4-based TiS2 / ZnS precursor in Step 5 to prepare the Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst. The calcination temperature is 450 - 550 °C, the heating rate is 5 °C / min, calcinate for 3 h, and keep it warm for 1 h.

3. The preparation method of the Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst according to claim 2, characterized in that, The working conditions of the centrifuge in Step 2 are a rotation speed of 3800 - 4500 rpm and a centrifugation time of 10 min.

4. The preparation method of the Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst according to claim 3, characterized in that, The reaction conditions in Step 4 are a reaction temperature of 60 - 70 °C and a reaction time of 2 - 2.5 h.

5. The preparation method of the Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst according to claim 4, characterized in that, The reaction conditions in Step 5 are a reaction temperature of 60 - 70 °C and a reaction time of 2 - 2.5 h.

6. The preparation method of the Fe3O4-based TiS2 / ZnS bilayer-loaded magnetic mercury removal catalyst according to claim 2, characterized in that, In Step 1, it is preferred that the molar ratio of FeCl3·6H2O and FeCl2·4H2O is 1.2:1, the pH value is 10, and the reaction is carried out at 80 °C for 6 h.

7. The preparation method of the Fe3O4-based TiS2 / ZnS double-layer supported magnetic mercury removal catalyst according to claim 4, characterized in that, In Step 4, the reaction temperature is preferably 60 °C and the reaction time is preferably 2 h.

8. The preparation method of the Fe3O4-based TiS2 / ZnS bilayer-loaded magnetic mercury removal catalyst according to claim 5, characterized in that, In Step 5, the reaction temperature is preferably 70 °C and the reaction time is preferably 2 h.

9. The preparation method of the Fe3O4-based TiS2 / ZnS bilayer-loaded magnetic mercury removal catalyst according to claim 2, characterized in that, In Step 6, nitrogen is introduced for protection with a flow rate of 50 ml / min.