Methanol steam reforming hydrogen production method based on electromagnetic induction heating

Abstract

The invention discloses a methanol steam reforming hydrogen production method based on electromagnetic induction heating, which is characterized in that a catalyst bed layer is arranged in a reactor, a magnetic conductive material layer is arranged close to the outer wall of the reactor, a spiral coil is arranged around the magnetic conductive material layer, and the spiral coil is communicated with a high-frequency power supply and electrified for induction heating; introducing methanol and water vapor into an inlet of the reactor, reacting to generate hydrogen, and discharging the hydrogen from an outlet of the reactor; wherein the component of the magnetic conductive material layer is nanoscale tin-cobalt alloy modified high-entropy ceramic powder, and the component of the catalyst bed layer is potassium modified carbon fiber loaded zinc-chromium spinel.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy production technology, specifically relating to a method for producing hydrogen from methanol via steam reforming based on electromagnetic induction heating. Background Technology

[0002] Methanol is a relatively safe, economical fuel with large reserves and convenient storage and transportation, and it is gaining increasing international consensus and widespread promotion.

[0003] Traditional methanol-to-hydrogen technologies mostly employ combustion heating or resistance heating methods, which have the following drawbacks: ① Combustion heating requires additional fuel, resulting in high carbon emissions and low thermal efficiency (typically <70%). ② Resistance heating relies on heat conduction, resulting in a slow heating rate (10-30 minutes from room temperature to 250℃) and poor temperature uniformity, leading to localized carbon buildup on the catalyst; ③ The system is large in size, making it difficult to start and stop quickly, and its dynamic response capability is insufficient.

[0004] ④ Some literature discloses microwave-heated methanol reforming or cracking, but microwave penetration depth is limited, and there are stringent requirements for reactor shape and catalyst distribution, and the equipment cost is high.

[0005] Patent CN114057161B discloses an electromagnetic induction heating methanol-water reforming hydrogen production device and its method. It utilizes electromagnetic induction heating to replace traditional heating methods, directly heating the reactor wall and catalyst through electromagnetic eddy currents to achieve rapid temperature rise, precise temperature control, and high energy efficiency, solving the problems of uneven temperature distribution, slow dynamic response, and high energy consumption in traditional technologies. The catalyst used in this patented technology is either a copper-based catalyst or a platinum-palladium-based catalyst. Copper-based catalysts operate in the temperature range of 230–270℃, are relatively inexpensive, and operate at lower temperatures, but have poor catalytic performance. Platinum-palladium-based catalysts operate in the temperature range of 350–500℃, have better catalytic performance, but are more expensive, operate at higher temperatures, and have higher operating costs. Overall, the hydrogen production efficiency of this patented technology still has significant room for improvement.

[0006] Furthermore, existing methanol-water reforming for hydrogen production typically operates under low space velocity conditions, and achieving high space velocity conditions presents challenges in areas such as improving methanol conversion rate and increasing hydrogen production efficiency. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for producing hydrogen from methanol via steam reforming based on electromagnetic induction heating.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A methanol-water vapor reforming hydrogen production method based on electromagnetic induction heating involves setting up a catalyst bed inside a reactor, placing a magnetically conductive material layer close to the outer wall of the reactor, and arranging a spiral coil around the magnetically conductive material layer. The spiral coil is connected to a high-frequency power supply for induction heating. When the temperature inside the reactor reaches 200–220°C, methanol and water vapor are introduced into the reactor inlet, where a reaction occurs to generate hydrogen gas, which is then discharged from the reactor outlet. The magnetically conductive material layer is composed of nano-scale tin-cobalt alloy-modified high-entropy ceramic powder, and the catalyst bed is composed of potassium-modified carbon fiber-supported zinc-chromium spinel.

[0009] Preferably, the thickness of the magnetically conductive material layer is 1 to 3 times the skin depth, and the skin depth δ is calculated by the formula δ=√(2ρ / ωμ), where ρ is the resistivity of the material, ω is the angular frequency, and μ is the permeability.

[0010] Preferably, the induction heating current frequency is 10–100 kHz, and the power density is 5–20 W / cm². 3 .

[0011] Preferably, the molar ratio of methanol to water vapor is 1:1.1 to 1.2, and the methanol liquid hourly space velocity is 7000 to 8000 h⁻¹. -1 .

[0012] Preferably, the magnetic material layer is obtained by uniformly spraying nano-sized tin-cobalt alloy modified high-entropy ceramic powder onto the outer wall of the reactor using plasma spraying. The plasma spraying process conditions are: arc current 500-520V, spraying distance 110mm, powder feeding rate 20-25g / min, hydrogen pressure 0.6-0.8MPa, hydrogen flow rate 40-50L / h, argon pressure 1.2-1.5MPa, argon flow rate 1500-1600L / h; and the thickness of the magnetic material layer is 500-600μm.

[0013] Preferably, the nanoscale tin-cobalt alloy modified high-entropy ceramic powder is prepared by the following method: (A) First, sodium borohydride is uniformly dispersed in diethylene glycol to obtain a sodium borohydride solution; then, tin chloride and cobalt chloride are uniformly dispersed in diethylene glycol to obtain a metal ion solution. (B) The high-entropy ceramic powder is then pretreated with poly(propyleneamine hydrochloride) to obtain pretreated high-entropy ceramic powder; (C) Then the pretreated high-entropy ceramic powder is ultrasonically dispersed in a sodium borohydride diethylene glycol solution and heated to 90-100°C under argon protection to obtain a premixed solution; (D) Finally, under the conditions of heat preservation and stirring, the metal ion solution is added to the premixed solution, heated and stirred to react, and then post-processed to obtain the final product.

[0014] Further preferably, the mass ratio of pretreated high-entropy ceramic powder to tin chloride is 1:3-4, the molar ratio of sodium borohydride, tin chloride, and cobalt chloride is 3-4:0.5-0.7:0.8-1, the concentration of sodium borohydride solution is 0.8-1 mol / L, and the concentration of metal ion solution is 4-5 mol / L.

[0015] More preferably, the high-entropy ceramic powder is (MgCoNiCuZn)O with a particle size of 20-30 μm, prepared according to the reference "Performance of High-Entropy Oxide Ceramics (MgCoNiCuZn)O Synthesized by Flash Firing" (Li Wangguo et al., Journal of Inorganic Materials, 2022, Vol. 12, pp. 1289-1294).

[0016] A further preferred method for step (B) is as follows: first, the high-entropy ceramic powder is ultrasonically dispersed in a 3-5 mol / L sodium chloride aqueous solution, then a 10-15% (w / w) poly(propyleneamine hydrochloride) aqueous solution is added, stirred and mixed, centrifuged to collect the precipitate, and washed with water; wherein, the mass ratio of the high-entropy ceramic powder, sodium chloride aqueous solution, and poly(propyleneamine hydrochloride) aqueous solution is 1:5-6:8-10, and the number average molecular weight of poly(propyleneamine hydrochloride) is 100,000-150,000.

[0017] More preferably, in step (D), the heating and stirring reaction conditions are: stirring at 180-200°C for 30-40 minutes.

[0018] In a further preferred embodiment, in step (D), the post-processing includes: naturally cooling to room temperature, adding an equal volume of anhydrous ethanol, centrifuging to collect the precipitate, and drying.

[0019] Preferably, the potassium-modified carbon fiber-supported zinc-chromium spinel is prepared by the following method: (a) Prepare a solution containing shale tar, add zinc nitrate, chromium nitrate and urea, stir and mix well to obtain a precursor solution; (b) Electrospinning; (c) Pre-oxidation and carbonization to obtain carbon fiber-supported zinc-chromium spinel; (d) Potassium modification.

[0020] More preferably, in step (a), the solution containing shale tar is prepared by the following method: first, polyvinylpyrrolidone is added to N,N-dimethylformamide and stirred at 60-70°C for 8-10 hours; then, shale tar is added, and the mixture is kept warm and stirred until homogeneous; finally, toluene is added dropwise, and the mixture is kept warm and stirred for 6-8 hours; the ratio of polyvinylpyrrolidone, N,N-dimethylformamide, shale tar, and toluene is 1g:8-10mL:0.8-1g:1mL.

[0021] More preferably, in step (a), the ratio of the solution containing shale tar, zinc nitrate, chromium nitrate and urea is 40-42 mL: 1 mmol: 2 mmol: 20-22 mmol.

[0022] More preferably, in step (b), the electrospinning conditions are: needle inner diameter 0.3-0.4 mm, feed rate 0.0006-0.0007 mm / s, voltage 18-20 V, spinning distance 18-20 cm, spinning temperature 30-35 °C, and relative humidity 50-60%.

[0023] In a further preferred embodiment, in step (c), the pre-oxidation conditions are: air flow rate of 80-100 mL / min, temperature increase to 300-320℃ at 2-3℃ / min, and pre-oxidation at this temperature for 2-3 hours.

[0024] In a further preferred embodiment, in step (c), the carbonization conditions are: nitrogen flow rate of 60-70 mL / min, temperature increase to 900-930℃ at 8-10℃ / min, and carbonization for 2-3 hours.

[0025] In a further preferred embodiment, the potassium modification method in step (d) is as follows: potassium nitrate is stirred and dispersed in a 0.8-1 mol / L acetic acid solution, followed by the addition of carbon fiber-supported zinc chromium spinel. The mixture is stirred at room temperature for 5-6 hours, drained, and then calcined at 400-450°C for 3-4 hours in an air atmosphere. The ratio of potassium nitrate, acetic acid solution, and carbon fiber-supported zinc chromium spinel is 0.3-0.5 g: 5-7 mL: 1-1.2 g.

[0026] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for producing hydrogen from methanol via steam reforming based on electromagnetic induction heating. A catalyst bed is arranged inside a reactor, and a magnetically conductive material layer is arranged close to the outer wall of the reactor. A spiral coil is arranged around the magnetically conductive material layer and connected to a high-frequency power supply for induction heating. When the temperature inside the reactor reaches 200–220°C, methanol and steam are introduced into the reactor inlet, where a reaction occurs to generate hydrogen, which is then discharged from the reactor outlet. The magnetically conductive material layer is composed of nano-scale tin-cobalt alloy modified high-entropy ceramic powder, and the catalyst bed is composed of potassium-modified carbon fiber-supported zinc-chromium spinel.

[0027] This invention integrates electromagnetic induction heating technology with a methanol steam reforming (or methanol cracking) reactor. It generates eddy current heat on the reactor wall through a high-frequency alternating magnetic field, directly providing a heat source for the endothermic reforming reaction (CH3OH + H2O → 3H2 + CO2) and the cracking reaction (CH3OH → 2H2 + CO). This invention allows for rapid start-up, heating the catalyst bed from room temperature to the reaction temperature within 30 seconds. It exhibits excellent temperature uniformity with an axial temperature difference of <±5℃ (compared to ±20℃ for traditional resistance heating), low energy consumption (40% lower than traditional heating), and significantly reduced carbon dioxide emissions. Furthermore, it supports millisecond-level power regulation under load fluctuations, adapting to the real-time hydrogen supply needs of fuel cells, and has broad application prospects.

[0028] This invention modifies high-entropy ceramic powder with nano-scale tin-cobalt alloy to form a magnetically conductive material layer, which is then closely attached to the outer wall of the reactor to achieve the aforementioned electromagnetic induction heating. This invention also develops potassium-modified carbon fiber-supported zinc-chromium spinel, which, when used as a catalyst bed component, significantly improves hydrogen production efficiency and greatly enhances methanol conversion under high space velocity conditions, achieving highly efficient hydrogen production through methanol-water reforming. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise specified, all products in this invention were purchased through market channels.

[0031] Example 1 A methanol-water vapor reforming method for hydrogen production based on electromagnetic induction heating involves setting up a catalyst bed inside a reactor, placing a magnetically conductive material layer close to the outer wall of the reactor, and arranging a spiral coil around the magnetically conductive material layer. The spiral coil is connected to a high-frequency power supply, and induction heating is performed when electricity is applied. When the temperature inside the reactor reaches 200°C, methanol and water vapor are introduced into the reactor inlet, where a reaction occurs to generate hydrogen gas, which is discharged from the reactor outlet. The magnetically conductive material layer is composed of nano-scale tin-cobalt alloy modified high-entropy ceramic powder, and the catalyst bed is composed of potassium-modified carbon fiber-supported zinc-chromium spinel.

[0032] The thickness of the magnetic material layer is 1 times the skin depth. The skin depth δ is calculated by the formula δ=√(2ρ / ωμ), where ρ is the resistivity of the material, ω is the angular frequency, and μ is the permeability.

[0033] The induction heating current has a frequency of 10kHz and a power density of 5W / cm².3 .

[0034] The molar ratio of methanol to water vapor is 1:1.1, and the liquid hourly space velocity (LHSV) of methanol is 7000 h⁻¹. -1 .

[0035] The magnetic material layer is obtained by uniformly spraying nano-sized tin-cobalt alloy modified high-entropy ceramic powder onto the outer wall of the reactor using plasma spraying. The plasma spraying process conditions are: arc current 500V, spraying distance 110mm, powder feeding rate 20g / min, hydrogen pressure 0.6MPa, hydrogen flow rate 40L / h, argon pressure 1.2MPa, and argon flow rate 1500L / h. The thickness of the magnetic material layer is 500μm.

[0036] The nanoscale tin-cobalt alloy-modified high-entropy ceramic powder was prepared by the following method: (A) First, sodium borohydride is uniformly dispersed in diethylene glycol to obtain a sodium borohydride solution; then, tin chloride and cobalt chloride are uniformly dispersed in diethylene glycol to obtain a metal ion solution. (B) The high-entropy ceramic powder is then pretreated with poly(acrylamine hydrochloride) to obtain pretreated high-entropy ceramic powder. The specific method is as follows: the high-entropy ceramic powder is first ultrasonically dispersed in a 3 mol / L sodium chloride aqueous solution, then a 10% (w / w) poly(acrylamine hydrochloride) aqueous solution is added, stirred and mixed, centrifuged to collect the precipitate, and washed with water. The mass ratio of high-entropy ceramic powder, sodium chloride aqueous solution, and poly(acrylamine hydrochloride) aqueous solution is 1:5:8, and the number average molecular weight of poly(acrylamine hydrochloride) is 100,000. (C) Then the pretreated high-entropy ceramic powder was ultrasonically dispersed in a sodium borohydride diethylene glycol solution and heated to 90°C under argon protection to obtain a premixed solution; (D) Finally, under the conditions of heat preservation and stirring, the metal ion solution is added to the premixed solution, stirred at 180°C for 30 minutes, naturally cooled to room temperature, an equal volume of anhydrous ethanol is added, the precipitate is collected by centrifugation and dried to obtain the final product.

[0037] The mass ratio of pretreated high-entropy ceramic powder and tin chloride was 1:3, the molar ratio of sodium borohydride, tin chloride, and cobalt chloride was 3:0.5:0.8, the concentration of sodium borohydride solution was 0.8 mol / L, and the concentration of metal ion solution was 4 mol / L.

[0038] The high-entropy ceramic powder is (MgCoNiCuZn)O with a particle size of 20 μm, and was prepared with reference to the literature "Performance of High-Entropy Oxide Ceramics (MgCoNiCuZn)O Synthesized by Flash Firing" (Li Wangguo et al., Journal of Inorganic Materials, 2022, Vol. 12, pp. 1289-1294).

[0039] The potassium-modified carbon fiber-supported zinc-chromium spinel was prepared by the following method: (a) Prepare a solution containing shale tar, add zinc nitrate, chromium nitrate and urea, stir and mix well to obtain a precursor solution; The solution containing shale tar was prepared by the following method: first, polyvinylpyrrolidone was added to N,N-dimethylformamide and stirred at 60°C for 8 hours; then, shale tar was added, and the mixture was kept warm and stirred until homogeneous; finally, toluene was added dropwise, and the mixture was kept warm and stirred for another 6 hours. The ratio of polyvinylpyrrolidone, N,N-dimethylformamide, shale tar, and toluene was 1 g: 8 mL: 0.8 g: 1 mL. The ratio of the solution containing shale tar, zinc nitrate, chromium nitrate, and urea was 40 mL: 1 mmol: 2 mmol: 20 mmol. (b) Electrospinning; specific conditions are: needle inner diameter 0.3 mm, feed rate 0.0006 mm / s, voltage 18 V, spinning distance 18 cm, spinning temperature 30 °C, relative humidity 50%; (c) Pre-oxidation and carbonization to obtain carbon fiber-supported zinc-chromium spinel; The pre-oxidation conditions are: air flow rate of 80 mL / min, temperature increased to 300℃ at 2℃ / min, and pre-oxidation held at this temperature for 2 hours; The carbonization conditions were: nitrogen flow rate 60 mL / min, temperature increased to 900℃ at 8℃ / min, and carbonization for 2 hours; (d) Potassium modification; The specific method is as follows: Potassium nitrate is stirred and dispersed in 0.8 mol / L acetic acid solution, then carbon fiber loaded zinc chromium spinel is added, stirred at room temperature for 5 hours, drained, and calcined at 400℃ for 3 hours in air atmosphere; The ratio of potassium nitrate, acetic acid solution and carbon fiber loaded zinc chromium spinel is 0.3 g: 5 mL: 1 g.

[0040] Example 2 A methanol-water vapor reforming hydrogen production method based on electromagnetic induction heating involves setting up a catalyst bed inside a reactor, placing a magnetically conductive material layer close to the outer wall of the reactor, and arranging a spiral coil around the magnetically conductive material layer. The spiral coil is connected to a high-frequency power supply and induction heating is performed when electricity is applied. When the temperature inside the reactor reaches 220°C, methanol and water vapor are introduced into the reactor inlet, where a reaction occurs to generate hydrogen gas, which is discharged from the reactor outlet. The magnetically conductive material layer is composed of nano-scale tin-cobalt alloy modified high-entropy ceramic powder, and the catalyst bed is composed of potassium-modified carbon fiber-supported zinc-chromium spinel.

[0041] The thickness of the magnetic material layer is three times the skin depth. The skin depth δ is calculated by the formula δ=√(2ρ / ωμ), where ρ is the resistivity of the material, ω is the angular frequency, and μ is the permeability.

[0042] The induction heating current has a frequency of 100kHz and a power density of 20W / cm². 3 .

[0043] The molar ratio of methanol to water vapor is 1:1.2, and the liquid hourly space velocity (LHSV) of methanol is 8000 h⁻¹. -1 .

[0044] The magnetic material layer is obtained by uniformly spraying nano-sized tin-cobalt alloy modified high-entropy ceramic powder onto the outer wall of the reactor using plasma spraying. The plasma spraying process conditions are: arc current 520V, spraying distance 110mm, powder feeding rate 25g / min, hydrogen pressure 0.8MPa, hydrogen flow rate 50L / h, argon pressure 1.5MPa, and argon flow rate 1600L / h. The thickness of the magnetic material layer is 600μm.

[0045] The nanoscale tin-cobalt alloy-modified high-entropy ceramic powder was prepared by the following method: (A) First, sodium borohydride is uniformly dispersed in diethylene glycol to obtain a sodium borohydride solution; then, tin chloride and cobalt chloride are uniformly dispersed in diethylene glycol to obtain a metal ion solution. (B) The high-entropy ceramic powder is then pretreated with poly(acrylamine hydrochloride) to obtain pretreated high-entropy ceramic powder. The specific method is as follows: the high-entropy ceramic powder is first ultrasonically dispersed in a 5 mol / L sodium chloride aqueous solution, then a 15% (w / w) poly(acrylamine hydrochloride) aqueous solution is added, stirred and mixed, centrifuged to collect the precipitate, and washed with water. The mass ratio of high-entropy ceramic powder, sodium chloride aqueous solution, and poly(acrylamine hydrochloride) aqueous solution is 1:6:10, and the number average molecular weight of poly(acrylamine hydrochloride) is 150,000. (C) Then the pretreated high-entropy ceramic powder was ultrasonically dispersed in a sodium borohydride diethylene glycol solution and heated to 100°C under argon protection to obtain a premixed solution; (D) Finally, under the conditions of heat preservation and stirring, the metal ion solution is added to the premixed solution, the mixture is stirred at 200°C for 40 minutes, and then naturally cooled to room temperature. An equal volume of anhydrous ethanol is added, the precipitate is collected by centrifugation and dried to obtain the final product.

[0046] The mass ratio of pretreated high-entropy ceramic powder and tin chloride is 1:4, the molar ratio of sodium borohydride, tin chloride, and cobalt chloride is 4:0.7:1, the concentration of sodium borohydride solution is 1 mol / L, and the concentration of metal ion solution is 5 mol / L.

[0047] The high-entropy ceramic powder is (MgCoNiCuZn)O with a particle size of 30 μm, and was prepared with reference to the literature "Performance of High-Entropy Oxide Ceramics (MgCoNiCuZn)O Synthesized by Flash Firing" (Li Wangguo et al., Journal of Inorganic Materials, 2022, Vol. 12, pp. 1289-1294).

[0048] The potassium-modified carbon fiber-supported zinc-chromium spinel was prepared by the following method: (a) Prepare a solution containing shale tar, add zinc nitrate, chromium nitrate and urea, stir and mix well to obtain a precursor solution; The solution containing shale tar was prepared by the following method: first, polyvinylpyrrolidone was added to N,N-dimethylformamide and stirred at 70°C for 10 hours; then, shale tar was added, and the mixture was kept warm and stirred until homogeneous; finally, toluene was added dropwise, and the mixture was kept warm and stirred for another 8 hours. The ratio of polyvinylpyrrolidone, N,N-dimethylformamide, shale tar, and toluene was 1 g: 10 mL: 1 g: 1 mL. The ratio of the solution containing shale tar, zinc nitrate, chromium nitrate, and urea was 42 mL: 1 mmol: 2 mmol: 22 mmol. (b) Electrospinning; specific conditions are: needle inner diameter 0.4 mm, feed rate 0.0007 mm / s, voltage 20 V, spinning distance 20 cm, spinning temperature 35 °C, relative humidity 60%; (c) Pre-oxidation and carbonization to obtain carbon fiber-supported zinc-chromium spinel; The pre-oxidation conditions are: air flow rate of 100 mL / min, temperature increased to 320℃ at 3℃ / min, and pre-oxidation is carried out at this temperature for 3 hours; The carbonization conditions were: nitrogen flow rate 70 mL / min, temperature increased to 930℃ at 10℃ / min, and carbonization for 3 hours; (d) Potassium modification; The specific method is as follows: Potassium nitrate is stirred and dispersed in 1 mol / L acetic acid solution, then carbon fiber loaded zinc chromium spinel is added, stirred at room temperature for 6 hours, drained, and calcined at 450℃ for 4 hours in air atmosphere; The ratio of potassium nitrate, acetic acid solution and carbon fiber loaded zinc chromium spinel is 0.5g:7mL:1.2g.

[0049] Example 3 A methanol-water vapor reforming method for hydrogen production based on electromagnetic induction heating involves setting up a catalyst bed inside a reactor, placing a magnetically conductive material layer close to the outer wall of the reactor, and arranging a spiral coil around the magnetically conductive material layer. The spiral coil is connected to a high-frequency power supply for induction heating. When the temperature inside the reactor reaches 210°C, methanol and water vapor are introduced into the reactor inlet, where a reaction occurs to generate hydrogen gas, which is then discharged from the reactor outlet. The magnetically conductive material layer is composed of nano-scale tin-cobalt alloy-modified high-entropy ceramic powder, and the catalyst bed is composed of potassium-modified carbon fiber-supported zinc-chromium spinel.

[0050] The thickness of the magnetic material layer is twice the skin depth. The skin depth δ is calculated by the formula δ=√(2ρ / ωμ), where ρ is the resistivity of the material, ω is the angular frequency, and μ is the permeability.

[0051] The induction heating current has a frequency of 80kHz and a power density of 12W / cm². 3 .

[0052] The molar ratio of methanol to water vapor is 1:1.2, and the liquid hourly space velocity (LHSV) of methanol is 7500 h⁻¹. -1 .

[0053] The magnetic material layer is obtained by uniformly spraying nano-sized tin-cobalt alloy modified high-entropy ceramic powder onto the outer wall of the reactor using plasma spraying. The plasma spraying process conditions are: arc current 510V, spraying distance 110mm, powder feeding rate 22g / min, hydrogen pressure 0.7MPa, hydrogen flow rate 45L / h, argon pressure 1.3MPa, and argon flow rate 1550L / h. The thickness of the magnetic material layer is 550μm.

[0054] The nanoscale tin-cobalt alloy-modified high-entropy ceramic powder was prepared by the following method: (A) First, sodium borohydride is uniformly dispersed in diethylene glycol to obtain a sodium borohydride solution; then, tin chloride and cobalt chloride are uniformly dispersed in diethylene glycol to obtain a metal ion solution. (B) The high-entropy ceramic powder is then pretreated with poly(acrylamine hydrochloride) to obtain pretreated high-entropy ceramic powder. The specific method is as follows: the high-entropy ceramic powder is first ultrasonically dispersed in a 4 mol / L sodium chloride aqueous solution, then a 12% (w / w) poly(acrylamine hydrochloride) aqueous solution is added, stirred and mixed, centrifuged to collect the precipitate, and washed with water. The mass ratio of high-entropy ceramic powder, sodium chloride aqueous solution, and poly(acrylamine hydrochloride) aqueous solution is 1:5:9, and the number average molecular weight of poly(acrylamine hydrochloride) is 120,000. (C) Then the pretreated high-entropy ceramic powder was ultrasonically dispersed in a sodium borohydride diethylene glycol solution and heated to 95°C under argon protection to obtain a premixed solution; (D) Finally, under the conditions of heat preservation and stirring, the metal ion solution is added to the premixed solution, stirred at 190°C for 35 minutes, naturally cooled to room temperature, an equal volume of anhydrous ethanol is added, the precipitate is collected by centrifugation and dried to obtain the final product.

[0055] The mass ratio of pretreated high-entropy ceramic powder to tin chloride was 1:3.5, the molar ratio of sodium borohydride, tin chloride, and cobalt chloride was 3.5:0.6:0.9, the concentration of sodium borohydride solution was 0.9 mol / L, and the concentration of metal ion solution was 4.5 mol / L.

[0056] The high-entropy ceramic powder is (MgCoNiCuZn)O with a particle size of 20 μm, and was prepared with reference to the literature "Performance of High-Entropy Oxide Ceramics (MgCoNiCuZn)O Synthesized by Flash Firing" (Li Wangguo et al., Journal of Inorganic Materials, 2022, Vol. 12, pp. 1289-1294).

[0057] The potassium-modified carbon fiber-supported zinc-chromium spinel was prepared by the following method: (a) Prepare a solution containing shale tar, add zinc nitrate, chromium nitrate and urea, stir and mix well to obtain a precursor solution; The solution containing shale tar was prepared by the following method: first, polyvinylpyrrolidone was added to N,N-dimethylformamide and stirred at 65°C for 9 hours; then, shale tar was added, and the mixture was kept warm and stirred until homogeneous; finally, toluene was added dropwise, and the mixture was kept warm and stirred for another 7 hours. The ratio of polyvinylpyrrolidone, N,N-dimethylformamide, shale tar, and toluene was 1 g: 9 mL: 0.9 g: 1 mL. The ratio of the solution containing shale tar, zinc nitrate, chromium nitrate, and urea was 41 mL: 1 mmol: 2 mmol: 21 mmol; (b) Electrospinning; specific conditions are: needle inner diameter 0.3 mm, feed rate 0.0006 mm / s, voltage 19 V, spinning distance 19 cm, spinning temperature 33 °C, relative humidity 55%; (c) Pre-oxidation and carbonization to obtain carbon fiber-supported zinc-chromium spinel; The pre-oxidation conditions are: air flow rate of 90 mL / min, temperature increased to 310℃ at 2℃ / min, and pre-oxidation held at this temperature for 2 hours; The carbonization conditions were: nitrogen flow rate 65 mL / min, temperature increased to 910℃ at 9℃ / min, and carbonization for 3 hours; (d) Potassium modification; The specific method is as follows: Potassium nitrate is stirred and dispersed in 0.9 mol / L acetic acid solution, then carbon fiber loaded zinc chromium spinel is added, stirred at room temperature for 5 hours, drained, and calcined at 420℃ for 3 hours in air atmosphere; The ratio of potassium nitrate, acetic acid solution and carbon fiber loaded zinc chromium spinel is 0.4 g: 6 mL: 1.1 g.

[0058] Comparative Example 1 A methanol-water vapor reforming hydrogen production method based on electromagnetic induction heating involves setting a catalyst bed inside a reactor, placing a magnetically conductive material layer close to the outer wall of the reactor, and arranging a spiral coil around the magnetically conductive material layer. The spiral coil is connected to a high-frequency power supply and induction heating is performed when electricity is applied. When the temperature inside the reactor reaches 200°C, methanol and water vapor are introduced into the reactor inlet, where a reaction occurs to generate hydrogen gas, which is discharged from the reactor outlet. The magnetically conductive material layer is composed of high-entropy ceramic powder, and the catalyst bed is composed of potassium-modified carbon fiber-supported zinc-chromium spinel.

[0059] The thickness of the magnetic material layer is 1 times the skin depth. The skin depth δ is calculated by the formula δ=√(2ρ / ωμ), where ρ is the resistivity of the material, ω is the angular frequency, and μ is the permeability.

[0060] The induction heating current has a frequency of 10kHz and a power density of 5W / cm². 3 .

[0061] The molar ratio of methanol to water vapor is 1:1.1, and the liquid hourly space velocity (LHSV) of methanol is 7000 h⁻¹. -1 .

[0062] The magnetic material layer is obtained by uniformly spraying high-entropy ceramic powder onto the outer wall of the reactor using plasma spraying. The plasma spraying process conditions are: arc current 500V, spraying distance 110mm, powder feeding rate 20g / min, hydrogen pressure 0.6MPa, hydrogen flow rate 40L / h, argon pressure 1.2MPa, and argon flow rate 1500L / h. The thickness of the magnetic material layer is 500μm.

[0063] The high-entropy ceramic powder is (MgCoNiCuZn)O with a particle size of 20 μm, and was prepared with reference to the literature "Performance of High-Entropy Oxide Ceramics (MgCoNiCuZn)O Synthesized by Flash Firing" (Li Wangguo et al., Journal of Inorganic Materials, 2022, Vol. 12, pp. 1289-1294).

[0064] The potassium-modified carbon fiber-supported zinc-chromium spinel was prepared by the following method: (a) Prepare a solution containing shale tar, add zinc nitrate, chromium nitrate and urea, stir and mix well to obtain a precursor solution; The solution containing shale tar was prepared by the following method: first, polyvinylpyrrolidone was added to N,N-dimethylformamide and stirred at 60°C for 8 hours; then, shale tar was added, and the mixture was kept warm and stirred until homogeneous; finally, toluene was added dropwise, and the mixture was kept warm and stirred for another 6 hours. The ratio of polyvinylpyrrolidone, N,N-dimethylformamide, shale tar, and toluene was 1 g: 8 mL: 0.8 g: 1 mL. The ratio of the solution containing shale tar, zinc nitrate, chromium nitrate, and urea was 40 mL: 1 mmol: 2 mmol: 20 mmol. (b) Electrospinning; specific conditions are: needle inner diameter 0.3 mm, feed rate 0.0006 mm / s, voltage 18 V, spinning distance 18 cm, spinning temperature 30 °C, relative humidity 50%; (c) Pre-oxidation and carbonization to obtain carbon fiber-supported zinc-chromium spinel; The pre-oxidation conditions are: air flow rate of 80 mL / min, temperature increased to 300℃ at 2℃ / min, and pre-oxidation held at this temperature for 2 hours; The carbonization conditions were: nitrogen flow rate 60 mL / min, temperature increased to 900℃ at 8℃ / min, and carbonization for 2 hours; (d) Potassium modification; The specific method is as follows: Potassium nitrate is stirred and dispersed in 0.8 mol / L acetic acid solution, then carbon fiber loaded zinc chromium spinel is added, stirred at room temperature for 5 hours, drained, and calcined at 400℃ for 3 hours in air atmosphere; The ratio of potassium nitrate, acetic acid solution and carbon fiber loaded zinc chromium spinel is 0.3 g: 5 mL: 1 g.

[0065] Comparative Example 2 A methanol-water vapor reforming hydrogen production method based on electromagnetic induction heating involves setting up a catalyst bed inside a reactor, placing a magnetically conductive material layer close to the outer wall of the reactor, and arranging a spiral coil around the magnetically conductive material layer. The spiral coil is connected to a high-frequency power supply for induction heating. When the temperature inside the reactor reaches 200°C, methanol and water vapor are introduced into the reactor inlet, where a reaction occurs to generate hydrogen gas, which is then discharged from the reactor outlet. The magnetically conductive material layer is composed of nano-scale tin-cobalt alloy-modified high-entropy ceramic powder, and the catalyst bed is composed of carbon fiber-supported zinc-chromium spinel.

[0066] The thickness of the magnetic material layer is 1 times the skin depth. The skin depth δ is calculated by the formula δ=√(2ρ / ωμ), where ρ is the resistivity of the material, ω is the angular frequency, and μ is the permeability.

[0067] The induction heating current has a frequency of 10kHz and a power density of 5W / cm². 3 .

[0068] The molar ratio of methanol to water vapor is 1:1.1, and the liquid hourly space velocity (LHSV) of methanol is 7000 h⁻¹. -1 .

[0069] The magnetic material layer is obtained by uniformly spraying nano-sized tin-cobalt alloy modified high-entropy ceramic powder onto the outer wall of the reactor using plasma spraying. The plasma spraying process conditions are: arc current 500V, spraying distance 110mm, powder feeding rate 20g / min, hydrogen pressure 0.6MPa, hydrogen flow rate 40L / h, argon pressure 1.2MPa, and argon flow rate 1500L / h. The thickness of the magnetic material layer is 500μm.

[0070] The nanoscale tin-cobalt alloy-modified high-entropy ceramic powder was prepared by the following method: (A) First, sodium borohydride is uniformly dispersed in diethylene glycol to obtain a sodium borohydride solution; then, tin chloride and cobalt chloride are uniformly dispersed in diethylene glycol to obtain a metal ion solution. (B) The high-entropy ceramic powder is then pretreated with poly(acrylamine hydrochloride) to obtain pretreated high-entropy ceramic powder. The specific method is as follows: the high-entropy ceramic powder is first ultrasonically dispersed in a 3 mol / L sodium chloride aqueous solution, then a 10% (w / w) poly(acrylamine hydrochloride) aqueous solution is added, stirred and mixed, centrifuged to collect the precipitate, and washed with water. The mass ratio of high-entropy ceramic powder, sodium chloride aqueous solution, and poly(acrylamine hydrochloride) aqueous solution is 1:5:8, and the number average molecular weight of poly(acrylamine hydrochloride) is 100,000. (C) Then the pretreated high-entropy ceramic powder was ultrasonically dispersed in a sodium borohydride diethylene glycol solution and heated to 90°C under argon protection to obtain a premixed solution; (D) Finally, under the conditions of heat preservation and stirring, the metal ion solution is added to the premixed solution, stirred at 180°C for 30 minutes, naturally cooled to room temperature, an equal volume of anhydrous ethanol is added, the precipitate is collected by centrifugation and dried to obtain the final product.

[0071] The mass ratio of pretreated high-entropy ceramic powder and tin chloride was 1:3, the molar ratio of sodium borohydride, tin chloride, and cobalt chloride was 3:0.5:0.8, the concentration of sodium borohydride solution was 0.8 mol / L, and the concentration of metal ion solution was 4 mol / L.

[0072] The high-entropy ceramic powder is (MgCoNiCuZn)O with a particle size of 20 μm, and was prepared with reference to the literature "Performance of High-Entropy Oxide Ceramics (MgCoNiCuZn)O Synthesized by Flash Firing" (Li Wangguo et al., Journal of Inorganic Materials, 2022, Vol. 12, pp. 1289-1294).

[0073] The carbon fiber-loaded zinc-chromium spinel is prepared by the following method: (a) Prepare a solution containing shale tar, add zinc nitrate, chromium nitrate and urea, stir and mix well to obtain a precursor solution; The solution containing shale tar was prepared by the following method: first, polyvinylpyrrolidone was added to N,N-dimethylformamide and stirred at 60°C for 8 hours; then, shale tar was added, and the mixture was kept warm and stirred until homogeneous; finally, toluene was added dropwise, and the mixture was kept warm and stirred for another 6 hours. The ratio of polyvinylpyrrolidone, N,N-dimethylformamide, shale tar, and toluene was 1 g: 8 mL: 0.8 g: 1 mL. The ratio of the solution containing shale tar, zinc nitrate, chromium nitrate, and urea was 40 mL: 1 mmol: 2 mmol: 20 mmol. (b) Electrospinning; specific conditions are: needle inner diameter 0.3 mm, feed rate 0.0006 mm / s, voltage 18 V, spinning distance 18 cm, spinning temperature 30 °C, relative humidity 50%; (c) Pre-oxidation and carbonization to obtain carbon fiber-supported zinc-chromium spinel; The pre-oxidation conditions are: air flow rate of 80 mL / min, temperature increased to 300℃ at 2℃ / min, and pre-oxidation held at this temperature for 2 hours; The carbonization conditions were: nitrogen flow rate 60 mL / min, temperature increased to 900℃ at 8℃ / min, and carbonization for 2 hours.

[0074] Comparative Example 3 A methanol-water vapor reforming hydrogen production method based on electromagnetic induction heating involves setting up a catalyst bed inside a reactor, placing a magnetically conductive material layer close to the outer wall of the reactor, and arranging a spiral coil around the magnetically conductive material layer. The spiral coil is connected to a high-frequency power supply, and induction heating is performed when electricity is applied. When the temperature inside the reactor reaches 200°C, methanol and water vapor are introduced into the reactor inlet, where a reaction occurs to generate hydrogen gas, which is discharged from the reactor outlet. The magnetically conductive material layer is composed of nano-scale tin-cobalt alloy modified high-entropy ceramic powder, and the catalyst bed is composed of potassium-modified carbon fiber-supported zinc spinel.

[0075] The thickness of the magnetic material layer is 1 times the skin depth. The skin depth δ is calculated by the formula δ=√(2ρ / ωμ), where ρ is the resistivity of the material, ω is the angular frequency, and μ is the permeability.

[0076] The induction heating current has a frequency of 10kHz and a power density of 5W / cm². 3 .

[0077] The molar ratio of methanol to water vapor is 1:1.1, and the liquid hourly space velocity (LHSV) of methanol is 7000 h⁻¹. -1 .

[0078] The magnetic material layer is obtained by uniformly spraying nano-sized tin-cobalt alloy modified high-entropy ceramic powder onto the outer wall of the reactor using plasma spraying. The plasma spraying process conditions are: arc current 500V, spraying distance 110mm, powder feeding rate 20g / min, hydrogen pressure 0.6MPa, hydrogen flow rate 40L / h, argon pressure 1.2MPa, and argon flow rate 1500L / h. The thickness of the magnetic material layer is 500μm.

[0079] The nanoscale tin-cobalt alloy-modified high-entropy ceramic powder was prepared by the following method: (A) First, sodium borohydride is uniformly dispersed in diethylene glycol to obtain a sodium borohydride solution; then, tin chloride and cobalt chloride are uniformly dispersed in diethylene glycol to obtain a metal ion solution. (B) The high-entropy ceramic powder is then pretreated with poly(acrylamine hydrochloride) to obtain pretreated high-entropy ceramic powder. The specific method is as follows: the high-entropy ceramic powder is first ultrasonically dispersed in a 3 mol / L sodium chloride aqueous solution, then a 10% (w / w) poly(acrylamine hydrochloride) aqueous solution is added, stirred and mixed, centrifuged to collect the precipitate, and washed with water. The mass ratio of high-entropy ceramic powder, sodium chloride aqueous solution, and poly(acrylamine hydrochloride) aqueous solution is 1:5:8, and the number average molecular weight of poly(acrylamine hydrochloride) is 100,000. (C) Then the pretreated high-entropy ceramic powder was ultrasonically dispersed in a sodium borohydride diethylene glycol solution and heated to 90°C under argon protection to obtain a premixed solution; (D) Finally, under the conditions of heat preservation and stirring, the metal ion solution is added to the premixed solution, stirred at 180°C for 30 minutes, naturally cooled to room temperature, an equal volume of anhydrous ethanol is added, the precipitate is collected by centrifugation and dried to obtain the final product.

[0080] The mass ratio of pretreated high-entropy ceramic powder and tin chloride was 1:3, the molar ratio of sodium borohydride, tin chloride, and cobalt chloride was 3:0.5:0.8, the concentration of sodium borohydride solution was 0.8 mol / L, and the concentration of metal ion solution was 4 mol / L.

[0081] The high-entropy ceramic powder is (MgCoNiCuZn)O with a particle size of 20 μm, and was prepared with reference to the literature "Performance of High-Entropy Oxide Ceramics (MgCoNiCuZn)O Synthesized by Flash Firing" (Li Wangguo et al., Journal of Inorganic Materials, 2022, Vol. 12, pp. 1289-1294).

[0082] The potassium-modified carbon fiber-supported zinc spinel was prepared by the following method: (a) Prepare a solution containing shale tar, add zinc nitrate, aluminum nitrate and urea, stir and mix well to obtain a precursor solution; The solution containing shale tar was prepared by the following method: first, polyvinylpyrrolidone was added to N,N-dimethylformamide and stirred at 60°C for 8 hours; then, shale tar was added, and the mixture was kept warm and stirred until homogeneous; finally, toluene was added dropwise, and the mixture was kept warm and stirred for another 6 hours. The ratio of polyvinylpyrrolidone, N,N-dimethylformamide, shale tar, and toluene was 1 g: 8 mL: 0.8 g: 1 mL. The ratio of the solution containing shale tar, zinc nitrate, aluminum nitrate, and urea was 40 mL: 1 mmol: 2 mmol: 20 mmol. (b) Electrospinning; specific conditions are: needle inner diameter 0.3 mm, feed rate 0.0006 mm / s, voltage 18 V, spinning distance 18 cm, spinning temperature 30 °C, relative humidity 50%; (c) Pre-oxidation and carbonization to obtain carbon fiber-supported zinc spinel; The pre-oxidation conditions are: air flow rate of 80 mL / min, temperature increased to 300℃ at 2℃ / min, and pre-oxidation held at this temperature for 2 hours; The carbonization conditions were: nitrogen flow rate 60 mL / min, temperature increased to 900℃ at 8℃ / min, and carbonization for 2 hours; (d) Potassium modification; The specific method is as follows: Potassium nitrate is stirred and dispersed in 0.8 mol / L acetic acid solution, then carbon fiber loaded zinc spinel is added, stirred at room temperature for 5 hours, drained, and calcined at 400℃ for 3 hours in air atmosphere; The ratio of potassium nitrate, acetic acid solution and carbon fiber loaded zinc spinel is 0.3 g: 5 mL: 1 g.

[0083] The hydrogen production efficiency of the methanol steam reforming hydrogen production methods in Examples 1-3 and Comparative Examples 1-3 was investigated, specifically including methanol conversion rate, H2 content of reformed gas (dry gas), and CO content of reformed gas (dry gas). The results are shown in Table 1.

[0084] Table 1. Comparison of methods for hydrogen production via methanol steam reforming As shown in Table 1, the methanol conversion rate of the methods in Examples 1 to 3 is close to 100%, the reformed gas has a high H2 content and a low CO content, which means that the products are mainly reformed products H2 and CO2, with only a small amount of cracked product CO, indicating that efficient hydrogen production was achieved under high space velocity conditions.

[0085] The high-entropy ceramic powder in Comparative Example 1 was not modified with nano-scale tin-cobalt alloy, the carbon fiber-supported zinc-chromium spinel in Comparative Example 2 was not modified with potassium, and the methanol conversion rate and H2 content in Comparative Example 3 were significantly reduced when carbon fiber-supported zinc-chromium spinel was replaced with carbon fiber-supported zinc spinel. This indicates that the material selection of the magnetic material layer and catalyst bed directly affects the hydrogen production effect.

[0086] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of individual raw materials in the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for producing hydrogen from methanol via steam reforming based on electromagnetic induction heating, characterized in that, A catalyst bed is set inside the reactor, and a magnetic material layer is set in close contact with the outer wall of the reactor. A spiral coil is set around the magnetic material layer and connected to a high-frequency power supply for induction heating. When the temperature inside the reactor reaches 200-220°C, methanol and water vapor are introduced into the reactor inlet, where a reaction occurs to generate hydrogen gas, which is discharged from the reactor outlet. The magnetic material layer is composed of nano-sized tin-cobalt alloy modified high-entropy ceramic powder, and the catalyst bed is composed of potassium-modified carbon fiber-supported zinc-chromium spinel.

2. The method according to claim 1, characterized in that, The induction heating current frequency is 10–100 kHz, and the power density is 5–20 W / cm². 3 .

3. The method according to claim 1, characterized in that, The molar ratio of methanol to water vapor is 1:1.1–1.2, and the liquid hourly space velocity (LHSV) of methanol is 7000–8000 h⁻¹. -1 .

4. The method according to claim 1, characterized in that, The magnetic material layer is obtained by uniformly spraying nano-sized tin-cobalt alloy modified high-entropy ceramic powder onto the outer wall of the reactor using plasma spraying. The plasma spraying process conditions are: arc current 500-520V, spraying distance 110mm, powder feeding rate 20-25g / min, hydrogen pressure 0.6-0.8MPa, hydrogen flow rate 40-50L / h, argon pressure 1.2-1.5MPa, argon flow rate 1500-1600L / h; the thickness of the magnetic material layer is 500-600μm.

5. The method according to claim 1, characterized in that, The nanoscale tin-cobalt alloy-modified high-entropy ceramic powder was prepared by the following method: (A) First, sodium borohydride is uniformly dispersed in diethylene glycol to obtain a sodium borohydride solution; then, tin chloride and cobalt chloride are uniformly dispersed in diethylene glycol to obtain a metal ion solution. (B) The high-entropy ceramic powder is then pretreated with poly(propyleneamine hydrochloride) to obtain pretreated high-entropy ceramic powder; (C) Then the pretreated high-entropy ceramic powder is ultrasonically dispersed in a sodium borohydride diethylene glycol solution and heated to 90-100°C under argon protection to obtain a premixed solution; (D) Finally, under the conditions of heat preservation and stirring, the metal ion solution is added to the premixed solution, heated and stirred to react, and then post-processed to obtain the final product.

6. The method according to claim 5, characterized in that, The mass ratio of pretreated high-entropy ceramic powder to tin chloride is 1:3-4, the molar ratio of sodium borohydride, tin chloride, and cobalt chloride is 3-4:0.5-0.7:0.8-1, the concentration of sodium borohydride solution is 0.8-1 mol / L, and the concentration of metal ion solution is 4-5 mol / L.

7. The method according to claim 5, characterized in that, The specific method of step (B) is as follows: First, the high-entropy ceramic powder is ultrasonically dispersed in a 3-5 mol / L sodium chloride aqueous solution. Then, a 10-15% (w / w) poly(acrylamine hydrochloride) aqueous solution is added, stirred and mixed, centrifuged to collect the precipitate, and washed with water. The mass ratio of the high-entropy ceramic powder, sodium chloride aqueous solution, and poly(acrylamine hydrochloride) aqueous solution is 1:5-6:8-10, and the number average molecular weight of poly(acrylamine hydrochloride) is 100,000-150,000. In step (D), the heating and stirring reaction conditions are: 180-200℃ for 30-40 minutes with stirring. In step (D), the post-processing includes: naturally cooling to room temperature, adding an equal volume of anhydrous ethanol, centrifuging to collect the precipitate, and drying.

8. The method according to claim 1, characterized in that, The potassium-modified carbon fiber-supported zinc-chromium spinel was prepared by the following method: (a) Prepare a solution containing shale tar, add zinc nitrate, chromium nitrate and urea, stir and mix well to obtain a precursor solution; (b) Electrospinning; (c) Pre-oxidation and carbonization to obtain carbon fiber-supported zinc-chromium spinel; (d) Potassium modification.

9. The method according to claim 8, characterized in that, In step (a), the solution containing shale tar is prepared by the following method: first, polyvinylpyrrolidone is added to N,N-dimethylformamide and stirred at 60-70°C for 8-10 hours; then, shale tar is added, and the mixture is kept warm and stirred until homogeneous; finally, toluene is added dropwise, and the mixture is kept warm and stirred for 6-8 hours. The ratio of polyvinylpyrrolidone, N,N-dimethylformamide, shale tar, and toluene is 1g:8-10mL:0.8-1g:1mL. The ratio of the solution containing shale tar, zinc nitrate, chromium nitrate, and urea is 40–42 mL: 1 mmol: 2 mmol: 20–22 mmol.

10. The method according to claim 8, characterized in that, In step (b), the electrospinning conditions are as follows: needle inner diameter 0.3–0.4 mm, feed rate 0.0006–0.0007 mm / s, voltage 18–20 V, spinning distance 18–20 cm, spinning temperature 30–35 °C, and relative humidity 50–60%. In step (c), the pre-oxidation conditions are: air flow rate of 80-100 mL / min, temperature increase to 300-320℃ at 2-3℃ / min, and pre-oxidation at this temperature for 2-3 hours; Carbonization conditions are: nitrogen flow rate 60-70 mL / min, temperature increased to 900-930℃ at 8-10℃ / min, carbonization for 2-3 hours; In step (d), the specific method for potassium modification is as follows: potassium nitrate is dispersed in 0.8-1 mol / L acetic acid solution, followed by the addition of carbon fiber-supported zinc chromium spinel. The mixture is stirred at room temperature for 5-6 hours, drained, and then calcined at 400-450℃ for 3-4 hours in air. The ratio of potassium nitrate, acetic acid solution, and carbon fiber-supported zinc chromium spinel is 0.3-0.5 g: 5-7 mL: 1-1.2 g.

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