A method and apparatus for the electrocatalytic decomposition of hydrogen sulfide to produce hydrogen and sulfur in a base decoupled manner

Abstract

The application discloses a method and device for preparing hydrogen and sulfur by alkaline decoupling electrocatalytic decomposition of hydrogen sulfide. The catholyte and the anolyte containing a reduced redox mediator are respectively introduced into the cathode chamber and the anode chamber of an electrocatalytic device, and under the action of an applied voltage, hydrogen is generated by hydrogen evolution reaction at the cathode, and the reduced redox mediator is oxidized to an oxidized redox mediator at the anode; the anolyte containing the oxidized redox mediator is transported to a reaction unit to react with hydrogen sulfide to generate elemental sulfur and a mixture of the reduced redox mediator and water, and the mixture of the reduced redox mediator and water is transported to the anode chamber for recycling. The method can avoid electrode deactivation caused by deposition of elemental sulfur on the anode surface, inhibit cross contamination and self-discharge caused by the redox mediator penetrating the membrane, and has the advantages of low voltage, good stability, high hydrogen Faraday efficiency and recyclable sulfur resources.

Description

Technical Field

[0001] This invention relates to the field of resource utilization and electrochemical energy conversion technology of sulfur-containing harmful gases, specifically to a method and apparatus for alkaline decoupling electrocatalytic decomposition of hydrogen sulfide to produce hydrogen and sulfur. Background Technology

[0002] Hydrogen sulfide is a highly toxic, corrosive, and foul-smelling sulfur-containing gas widely found in natural gas, shale gas, coalbed methane, oil refinery tail gas, coal chemical tail gas, biogas, and various sulfur-containing industrial emissions. Traditional industries often use the Claus process to treat hydrogen sulfide. This method converts the sulfur in hydrogen sulfide into sulfur, but the hydrogen is usually oxidized to water and cannot be recovered as hydrogen gas, resulting in a potential loss of energy value. Furthermore, the Claus process typically involves high-temperature processes, complex tail gas treatment units, and significant energy and equipment costs.

[0003] Theoretically, direct electrochemical decomposition of hydrogen sulfide can simultaneously produce hydrogen and elemental sulfur, offering the potential for waste-to-resource conversion and low-energy hydrogen production. However, during direct electrolysis, elemental sulfur deposition easily occurs on the anode surface, leading to electrode passivation, impaired mass transfer, and increased voltage, severely limiting the stability of continuous operation.

[0004] To overcome the aforementioned sulfur deposition problem, researchers have proposed a decoupled electrochemical system that separates the hydrogen evolution reaction from the hydrogen sulfide oxidation reaction. Sulfur conversion is mediated on the anode side using a redox medium, while hydrogen evolution is achieved on the cathode side. However, existing decoupled electrochemical systems typically rely on acidic media or small-molecule mediators, which can easily lead to problems such as equipment corrosion, decreased catalyst stability, membrane permeation, and self-discharge.

[0005] In recent years, alkaline systems have become an important research direction in this field due to their high efficiency in absorbing hydrogen sulfide and their mild operating environment. In alkaline systems, hydrogen sulfide can be efficiently absorbed by alkaline solutions to form H₂S or S₂. 2- While this method can significantly reduce gas-liquid mass transfer and corrosion problems, the alkaline hydrogen evolution reaction is limited by the water dissociation step, resulting in slow reaction kinetics. Some noble metals possess strong water dissociation capabilities and excellent hydrogen evolution activity. Among them, Ru and other noble metals have a certain cost advantage compared to Pt, but the adsorption strength of hydrogen intermediates on the surface of noble metals still needs further regulation. Therefore, there is an urgent need to develop a new system with efficient cathode catalysts, stable media, and low cross-contamination suitable for the decoupling decomposition of alkaline hydrogen sulfide. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for alkaline decoupled electrocatalytic decomposition of hydrogen sulfide to produce hydrogen and sulfur, so as to solve the problems of slow hydrogen evolution kinetics and cross-contamination and self-discharge caused by redox mediator membrane penetration in the existing alkaline system hydrogen sulfide electrochemical conversion.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a method for preparing hydrogen and sulfur by alkaline decoupling electrocatalytic decomposition of hydrogen sulfide, the method comprising the following steps: The catholyte and the anolyte containing the reduced redox medium are respectively introduced into the cathode chamber and anode chamber of the electrocatalytic device. Under the action of an applied voltage, hydrogen evolution reaction occurs at the cathode to generate hydrogen gas, and the reduced redox medium is oxidized to the oxidized redox medium at the anode. The anolyte containing the oxidized redox medium is transported to the reaction unit, where it reacts with hydrogen sulfide to generate elemental sulfur, as well as a mixture of the reduced redox medium and water. The elemental sulfur is collected, and the mixture of the reduced redox medium and water is transported to the anode chamber for recycling.

[0008] In the above technical solution, the supporting electrolyte for the catholyte and the anolyte is one of KOH and NaOH, and the supporting electrolyte for the catholyte and the anolyte is the same.

[0009] In the above technical solution, the electrocatalytic device further includes a cathode chamber, an anode chamber, and an anion exchange membrane for separating the cathode chamber and the anode chamber; the anion exchange membrane allows OH- - It conducts and inhibits the transmembrane migration of redox mediators.

[0010] In the above technical solution, further, the cathode of the electrocatalytic device is a noble metal-supported transition metal sulfide heterostructure electrode; in the noble metal-supported transition metal sulfide heterostructure electrode, the noble metal is one of Ru, Pt, Pd, Ir, and Rh, and the transition metal sulfide is one of Ni3S2, CoS2, FeS2, MoS2, and WS2. In this cathode, a heterostructure interface is formed between the noble metal and the transition metal sulfide. This interface can regulate the electronic structure of the noble metal, reduce the water dissociation energy barrier in the alkaline hydrogen evolution process, and shift the adsorption free energy of the hydrogen intermediate to the thermally neutral region, thereby improving the alkaline hydrogen evolution activity and stability.

[0011] In the above technical solution, the mass content of the noble metal in the noble metal-supported transition metal sulfide heterostructure electrode is 0.01wt%~20wt%, preferably 0.1wt%~5wt%.

[0012] In the above technical solution, the noble metal-supported transition metal sulfide heterostructure electrode is further prepared by the following method: (1) The conductive substrate is pretreated to remove oil, impurities and oxide layer from its surface to obtain a surface-activated conductive substrate; (2) The pretreated conductive substrate is placed in a reaction solution containing sulfur source for hydrothermal sulfidation reaction. The reaction temperature is 100~220 ℃ and the reaction time is 1~24 h, so that the transition metal sulfide grows in situ on the surface of the conductive substrate to obtain the transition metal sulfide modified electrode precursor. (3) The transition metal sulfide modified electrode precursor is placed in a solution containing Ru precursor and the Ru species are loaded onto the surface of the transition metal sulfide by impregnation reduction at a reaction temperature of 40~100 ℃ and a reaction time of 0.5~12 h to obtain Ru-loaded transition metal sulfide heterostructure electrode. (4) The obtained Ru-loaded transition metal sulfide heterostructure electrode was washed and then dried at 40~100 °C for 2~24 h. The conductive substrate is nickel foam or nickel mesh, and the pretreatment includes one or more of the following: deionized water cleaning, ethanol cleaning, pickling, ultrasonic treatment and drying. The sulfur source includes one or more of thioacetamide, thiourea, or sodium thiosulfate; The Ru precursor includes one or more of ruthenium trichloride, hydrated ruthenium trichloride, ruthenium chloride, ruthenium acetylacetonate, or other soluble ruthenium salts; In the above technical solution, the anode of the electrocatalytic device is further selected from carbon paper, carbon cloth, graphite sheet, graphite felt, glassy carbon, titanium sheet, and titanium mesh.

[0013] In the above technical solution, the redox mediator further comprises a reversible redox couple, wherein the reversible redox couple is selected from one of iron-based complex redox couples and quinone redox couples; the concentration of the redox mediator in the anolyte is 1×10⁻⁶. -3 ~2 M.

[0014] In the above technical solution, the iron-based complex redox couple further includes [Fe(CN)6]. 4- / [Fe(CN)6] 3- EDTA-Fe 2+ / EDTA-Fe 3+ One of them; the quinone redox couple includes one of hydroquinone / benzoquinone and its derivatives.

[0015] In the above technical solution, the anode of the electrocatalytic device is further selected from carbon paper, carbon cloth, graphite sheet, graphite felt, glassy carbon, titanium sheet, and titanium mesh.

[0016] In the above technical solution, the hydrogen sulfide-containing gas further includes one or more of the following: natural gas, shale gas, coalbed methane, refinery gas, biogas, and coke oven gas.

[0017] A second aspect of the present invention provides an apparatus for alkaline decoupling electrocatalytic decomposition of hydrogen sulfide to produce hydrogen and sulfur for carrying out the above-described method, comprising an electrocatalytic device, a reaction unit, a circulating pump, pipelines, and a product collection unit; the electrocatalytic device includes a cathode chamber, an anode chamber, and an anion exchange membrane for separating the cathode chamber and the anode chamber; the inlet of the reaction unit is connected to the outlet of the anode chamber via a pipeline, and the outlet of the reaction unit is connected to the inlet of the anode chamber via a circulating pump; the anode chamber includes an anode electrode and an anode bipolar plate; the cathode chamber includes a cathode electrode and a cathode bipolar plate; the anode bipolar plate and the cathode bipolar plate are provided with parallel flow channels or serpentine flow channels; the anode electrode is one of carbon paper, carbon cloth, graphite sheet, graphite felt, glassy carbon, titanium sheet, and titanium mesh; the cathode electrode is a noble metal-loaded transition metal sulfide heterostructure electrode.

[0018] In the above technical solution, the electrocatalytic device is further described as a flow-type structure.

[0019] The beneficial effects of this invention are as follows: (1) In this invention, the cathodic hydrogen evolution, electrochemical medium oxidation and sulfide chemical oxidation are carried out in different spaces, which effectively avoids the passivation problem caused by the direct deposition of elemental sulfur on the anode surface; (2) The present invention uses an alkaline system to absorb and convert hydrogen sulfide, which reduces the corrosion of the catalyst, membrane and electrolytic cell components by the acidic medium; (3) The present invention uses a noble metal-loaded transition metal sulfide heterostructure electrode as the cathode. A heterostructure interface is formed between the noble metal and the transition metal sulfide. This interface can regulate the electronic structure of the noble metal, reduce the water dissociation energy barrier in the alkaline hydrogen evolution process, and move the adsorption free energy of the hydrogen intermediate to the thermal neutral region, thereby improving the water dissociation and hydrogen intermediate conversion efficiency, and can achieve efficient hydrogen evolution at low overpotential. (4) The present invention uses a medium with a reversible redox couple as the anode medium. The redox medium has a fast reversible redox kinetics and a suitable redox potential under alkaline conditions, which can effectively drive the conversion of sulfides to elemental sulfur, avoid the high overpotential required by the traditional oxygen evolution reaction, and reduce the energy consumption of the whole cell. At the same time, the redox medium has low permeability in the anion exchange membrane, which is beneficial to reducing cross-contamination and self-discharge. (5) The present invention can simultaneously obtain high-purity hydrogen and recoverable elemental sulfur, thereby achieving harmless treatment and high-value utilization of toxic hydrogen sulfide waste gas; (6) The device of the present invention has a simple structure and can be used in conjunction with a flow electrolyzer, a gas absorption unit and a sulfur separation unit. It is suitable for the treatment of natural gas, refinery gas, biogas, coke oven gas and other sulfur-containing industrial tail gas. Attached Figure Description

[0020] Figure 1 The X-ray diffraction pattern of the Ru / Ni3S2-NF electrode in Embodiment 1 of the present invention; Figure 2 This is a transmission electron microscope image of the Ru / Ni3S2-NF electrode in Example 1 of the present invention; Figure 3 The LSV curves of electrocatalytic hydrogen evolution of the Ru / Ni3S2-NF electrode and the comparative electrode in Example 1 of this invention are shown. Figure 4 This is an X-ray diffraction pattern of the sulfur product obtained in Example 1 of the present invention; Figure 5 This is a diagram showing the hydrogen Faraday efficiency of the alkaline decoupled electrocatalytic system in Example 1 of the present invention. Figure 6 This is a schematic diagram of the apparatus for preparing hydrogen and sulfur by alkaline decoupling electrocatalytic decomposition of hydrogen sulfide according to the present invention. In the diagram: 1. Cathode chamber, 2. Anode chamber, 3. Reaction unit, 4. DC power supply, 5. Cathode electrode, 6. Anode electrode, 7. Anion exchange membrane, 8. Circulation pump, 9. Product collection unit. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Equivalent substitutions or combinations made by those skilled in the art, without departing from the concept of the present invention, regarding the types of noble metals, transition metal sulfides, conductive substrates, redox mediators, membrane materials, electrode dimensions, electrolyte concentrations, operating temperatures, flow rates, and device structures, should all fall within the scope of protection of the present invention.

[0022] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.

[0023] Example 1 In this embodiment, a Ru-supported Ni3S2 nickel foam (Ru / Ni3S2-NF) heterostructure electrode is used as the cathode electrode for alkaline decoupling electrocatalytic decomposition of hydrogen sulfide to produce hydrogen and sulfur.

[0024] The steps for preparing the cathode electrode are as follows: (1) Cut the nickel foam (NF) into 1 cm × 1.5 cm sheets, wash them with deionized water and ethanol in sequence, then place them in 1.0 M hydrochloric acid and sonicate for 30 min to remove the surface oxide layer. Then rinse them thoroughly with deionized water and dry them at room temperature. (2) Dissolve 0.32 g of thioacetamide in 20 mL of deionized water, transfer it to a 50 mL polytetrafluoroethylene-lined stainless steel reactor, and immerse the pretreated nickel foam in the solution and keep it at 180 °C for 6 h. (3) After the reaction was completed, the black product was taken out, washed thoroughly with deionized water and ethanol, and dried at room temperature to obtain the Ni3S2-NF precursor; (4) Dissolve 0.005 g RuCl3·H2O in a mixed solvent consisting of 20 mL deionized water and 10 mL ethylene glycol, immerse the Ni3S2-NF precursor in the solution, and keep it in an oil bath at 70 °C for 5 h to allow Ru species to undergo impregnation reduction deposition on the surface of Ni3S2-NF. (5) After the reaction, the sample was taken out, washed thoroughly with deionized water, and dried in an oven at 70 °C for 12 h to obtain the Ru / Ni3S2-NF electrode.

[0025] The obtained electrode was subjected to phase analysis using X-ray diffraction. For example... Figure 1 As shown, the nickel foam substrate exhibits characteristic diffraction peaks of metallic Ni; after hydrothermal sulfidation, the sample shows characteristic diffraction peaks of Ni3S2, indicating that Ni3S2 was successfully grown on the nickel foam surface. After loading Ru, no obvious Ru crystal phase diffraction peaks were observed in the sample, indicating that the Ru component loading was low or dispersed in the form of small-sized nanoclusters on the Ni3S2 surface.

[0026] Transmission electron microscopy was used to characterize the morphology and microstructure of the samples. For example... Figure 2 As shown, Ru nanoparticles or nanoclusters are distributed on the Ni3S2 surface. High-resolution transmission electron microscopy reveals lattice fringes belonging to Ni3S2 and metallic Ru, indicating that Ru was successfully loaded onto the Ni3S2 surface and formed a heterogeneous interface.

[0027] For comparison, Ni3S2-NF and Ru-NF electrodes were prepared, and the preparation methods are as follows: Ni3S2-NF electrode: (1) Cut the nickel foam (NF) into 1 cm × 1.5 cm sheets, wash them with deionized water and ethanol in sequence, then place them in 1.0 M hydrochloric acid and sonicate for 30 min to remove the surface oxide layer. Then rinse them thoroughly with deionized water and dry them at room temperature. (2) Dissolve 0.32 g of thioacetamide in 20 mL of deionized water, transfer it to a 50 mL polytetrafluoroethylene-lined stainless steel reactor, and immerse the pretreated nickel foam in the solution and keep it at 180 °C for 6 h. (3) After the reaction is complete, the black product is taken out, washed thoroughly with deionized water and ethanol, and dried at room temperature to obtain the Ni3S2-NF electrode.

[0028] Ru-NF electrode: (1) Cut the nickel foam (NF) into 1 cm × 1.5 cm sheets, wash them with deionized water and ethanol in sequence, then place them in 1.0 M hydrochloric acid and sonicate for 30 min to remove the surface oxide layer. Then rinse them thoroughly with deionized water and dry them at room temperature. (2) Dissolve 0.005 g RuCl3·H2O in a mixed solvent consisting of 20 mL deionized water and 10 mL ethylene glycol, immerse the pretreated nickel foam in the solution, and keep it in an oil bath at 70 °C for 5 h to allow Ru species to be impregnated and reduced on the surface of the nickel foam. (3) After the reaction, the sample was taken out, washed thoroughly with deionized water, and dried in an oven at 70 °C for 12 h to obtain the Ru-NF electrode.

[0029] The alkaline hydrogen evolution performance of Ru / Ni3S2-NF, Ni3S2-NF, Ru-NF, and bare nickel foam was evaluated using a three-electrode system in 1.0 M KOH electrolyte. The test results are as follows: Figure 3 As shown, Ru / / Ni3S2-NF at 10 mA cm -2 The overpotential at the current density is approximately 40.3 mV, and the Tafel slope is approximately 25.6 mV dec. - ¹, significantly superior to Ni3S2-NF, Ru-NF, and bare nickel foam. This result indicates that the heterointerface between Ru and Ni3S2 can effectively reduce the kinetic resistance of alkaline hydrogen evolution and improve the electrocatalytic hydrogen evolution activity.

[0030] Adopting such Figure 1The apparatus shown performs alkaline decoupled electrocatalytic decomposition of hydrogen sulfide to produce hydrogen and sulfur. The apparatus includes an electrocatalytic device, a reaction unit 3, a circulating pump 8, piping, and a product collection unit 9. The electrocatalytic device includes a cathode chamber 1, an anode chamber 2, and an anion exchange membrane 7 (FuMA-Tech, FAA-3-PK75, approximately 80 μm thick) separating the cathode and anode chambers. The outlet of the anode chamber 2 is connected to the inlet of the reaction unit 3 via a piping connection. The outlet of the reaction unit 3 is connected to the inlet of the anode chamber via the circulating pump 8. The anode chamber 2 includes an anode electrode 6 and an anode bipolar plate. The cathode chamber 1 includes a cathode electrode 5 and a cathode bipolar plate. Both the anode and cathode bipolar plates are equipped with serpentine flow channels. The electrocatalytic device uses a flow electrolyzer, where the cathode electrode is the aforementioned Ru / / Ni3S2-NF (effective electrode area 2 cm × 2 cm), the anode electrode is carbon paper, the cathode solution is 0.1 M KOH, and the anolyte is a mixture of 0.1 M KOH and 0.5 M KOH. A mixed solution of K4[Fe(CN)6] is used. During electrolysis, K4[Fe(CN)6] acts as a reduced redox medium, dissolving in the alkaline electrolyte and being transported to the anode chamber with the circulating electrolyte. Under the influence of an applied electric field, the reduced [Fe(CN)6]... 4- An electrochemical oxidation reaction occurs at the anode surface, releasing electrons to the anode and transforming into the oxidized state [Fe(CN)6]. 3- As electrolysis continues, the oxidized state of [Fe(CN)6] in the anolyte... 3- The content of [Fe(CN)6] gradually increases. The resulting anolyte containing the oxidized medium is then transported to the reaction unit via a circulation pipeline. In the reaction unit, the oxidized [Fe(CN)6]... 3- Instead of an electrode reaction, it acts as a chemical oxidant, reacting with sulfides in solution in a redox reaction. The sulfides donate electrons and are oxidized to form elemental sulfur (S). 0 And [Fe(CN)6] 3- After accepting electrons, it reverts to its reduced state [Fe(CN)6]. 4- The elemental sulfur produced in the reaction can be separated from the reaction solution through sedimentation, filtration, or other solid-liquid separation methods, while the regenerated reduced [Fe(CN)6]... 4- It then returns to the anode chamber with the circulating liquid, undergoes anodic electrochemical oxidation again, and is regenerated in the oxidized state [Fe(CN)6]. 3- Thus, the redox mediator is regenerated.

[0031] The anolyte (a mixed solution of 0.1 M KOH and 0.5 M K₄[Fe(CN)₆]) and the catholyte (0.1 M KOH) were respectively introduced into the anode and cathode chambers of a flow electrolytic cell. Under the applied voltage of 2.0 V, hydrogen evolution reaction occurred at the cathode to generate hydrogen gas, and the anode reduced Fe(CN)₆. 4-It is oxidized to the oxidized state [Fe(CN)6]. 3- ; Contains oxidized [Fe(CN)6] 3- The anolyte was fed to the reaction unit, where it underwent a chemical oxidation reaction with hydrogen sulfide to produce elemental sulfur and a mixture containing K₄[Fe(CN)₆] and water. The resulting yellow product was separated, washed, and dried, and then characterized by X-ray diffraction, such as... Figure 4 As shown, the diffraction peaks of the obtained product are consistent with those of the elemental sulfur standard card, indicating that the system can selectively oxidize sulfides to elemental sulfur.

[0032] In this device, 0.5 M Fe(CN)6 is introduced. 4- / [Fe(CN)6] 3- After the redox medium is applied, the electrolyzer can achieve a high current density at a relatively low voltage. At a battery voltage of 2.0 V, the current density can reach approximately 250 mA cm⁻¹. -2 During continuous electrolysis, the amount of hydrogen produced at the cathode is detected using a combination of water displacement and gas chromatography. Figure 5 As shown, the hydrogen Faraday efficiency remained above 96%, with an average of approximately 97.2%. This result indicates that cathode electrons are primarily used for hydrogen generation, with minimal side reactions. Stability testing of the device showed that after 8 hours of continuous operation at a 2.0 V battery voltage, the system maintained approximately 96% of its initial current density, demonstrating the good operational stability of the alkaline decoupled electrocatalytic system provided by this invention.

[0033] The above results demonstrate that the Ru-supported Ni3S2 foam nickel heterostructure electrode provided in this embodiment has excellent alkaline hydrogen evolution performance; after coupling the electrode with a reversible redox couple and an anion exchange membrane flow electrolyzer, efficient and stable conversion of hydrogen sulfide into hydrogen and elemental sulfur can be achieved.

[0034] Example 2 The difference from Example 1 is that in this example, the cathode electrode is a Pt-supported CoS2 nickel foam (Pt / CoS2-NF) heterostructure electrode, and the redox medium is EDTA-Fe. 2+ / EDTA-Fe 3+ The anolyte contains 0.5 M EDTA-Fe 2+ / EDTA-Fe 3+ A 0.1 M KOH solution of a redox couple. Specifically, the cathode electrode steps are as follows: A CoS2-NF precursor was prepared according to the preparation method of Example 1. After obtaining the CoS2-NF precursor, the Pt component was loaded onto the surface of CoS2-NF by impregnation reduction to obtain a Pt / CoS2-NF heterostructure electrode. The remaining electrolytic cell structure and testing conditions are the same as in Example 1.

[0035] The electrochemical performance of Pt / CoS2-NF was tested. In a 1.0 M KOH electrolyte, Pt / CoS2-NF exhibited excellent alkaline hydrogen evolution performance at 10 mA cm⁻¹. -2 The overpotential at the current density is approximately 35 mV. When used as a cathode in an alkaline decoupled electrocatalytic decomposition system for hydrogen sulfide, the system current density reaches approximately 230 mA cm⁻¹ at a battery voltage of 2.0 V. -2 After 8 hours of continuous operation, the electrode maintained approximately 94% of its initial current density, with a hydrogen Faraday efficiency of approximately 96.5%. This result indicates that, even after changing the type of transition metal sulfide, the noble metal-loaded transition metal sulfide heterostructure electrode can still achieve the decoupling conversion of hydrogen sulfide to hydrogen and elemental sulfur under alkaline conditions.

[0036] Example 3 The difference from Example 1 is that in this example, the cathode electrode is a Pd-supported FeS2 nickel foam (Pd / FeS2-NF) heterostructure electrode, and the anolyte is a solution containing 1 M Fe(CN)6. 4- / [Fe(CN)6] 3- A 0.1 M KOH solution was used. Specifically, the cathode electrode steps were as follows: A FeS2-NF precursor was prepared according to the preparation method of Example 1. After obtaining the FeS2-NF precursor, the Pd component was loaded onto the FeS2-NF surface by impregnation reduction to obtain a Pd / FeS2-NF heterostructure electrode. The remaining electrolytic cell structure and testing conditions were the same as in Example 1.

[0037] The electrochemical performance of Pd / FeS2-NF was tested. In a 1.0 M KOH electrolyte, Pd / FeS2-NF exhibited good alkaline hydrogen evolution activity at 10 mA cm⁻¹. -2 The overpotential at the current density is approximately 58 mV. When used as a cathode in an alkaline decoupled electrocatalytic decomposition system for hydrogen sulfide, the system current density reaches approximately 398 mA cm⁻¹ at a battery voltage of 2.0 V. -2 After running continuously for 8 hours, it maintains approximately 92% of the initial current density, and the hydrogen Faraday efficiency is approximately 95.8%.

[0038] Example 4 The difference from Example 1 is that in this example, the cathode electrode is an Ir-supported MoS2 nickel foam (Ir / MoS2-NF) heterostructure electrode, and the anolyte is a solution containing 0.1 M Fe(CN)6. 4- / [Fe(CN)6] 3-A 0.1 M KOH solution was used. Specifically, the cathode electrode steps were as follows: A MoS2-NF precursor was prepared according to the preparation method of Example 1. After obtaining the MoS2-NF precursor, the Ir component was loaded onto the surface of MoS2-NF by impregnation reduction to obtain an Ir / MoS2-NF heterostructure electrode. The remaining electrolytic cell structure and test conditions were the same as in Example 1.

[0039] The electrochemical performance of Ir / MoS2-NF was tested. In a 1.0 M KOH electrolyte, Ir / MoS2-NF exhibited good alkaline hydrogen evolution performance at 10 mA cm⁻¹. -2 The overpotential at the current density is approximately 52 mV. When used as a cathode in an alkaline decoupled electrocatalytic decomposition system for hydrogen sulfide, the system current density reaches approximately 45 mA cm⁻¹ at a battery voltage of 2.0 V. -2 After running continuously for 8 hours, it maintains approximately 93% of the initial current density, and the hydrogen Faraday efficiency is approximately 96.0%.

[0040] Example 5 The difference from Example 1 is that the cathode electrode in this example uses a Rh-supported Ni3S2 nickel foam (Rh / Ni3S2-NF) heterostructure electrode. Specifically, the cathode electrode is prepared as follows: after obtaining the Ni3S2-NF precursor, the Rh component is loaded onto the surface of Ni3S2-NF by impregnation reduction to obtain the Rh / Ni3S2-NF heterostructure electrode. The remaining electrolytic cell structure and testing conditions are the same as in Example 1.

[0041] The electrochemical performance of Rh / Ni3S2-NF was tested. In a 1.0 M KOH electrolyte, Rh / Ni3S2-NF exhibited good alkaline hydrogen evolution performance at 10 mA cm⁻¹. -2 The overpotential at the current density is approximately 48 mV. When used as a cathode in an alkaline decoupled electrocatalytic decomposition system for hydrogen sulfide, the system current density reaches approximately 230 mA cm⁻¹ at a battery voltage of 2.0 V. -2 After running continuously for 8 hours, it maintains approximately 91% of the initial current density, and the hydrogen Faraday efficiency is approximately 95.2%.

[0042] Example 6 The difference from Example 1 is that in this example, the cathode electrode is a Ru-supported CoS2 nickel foam (Ru / CoS2-NF) heterostructure electrode, and the anolyte is a 0.1 M KOH solution containing a 0.1 M hydroquinone / benzoquinone redox couple. Specifically, the cathode electrode preparation steps are as follows: First, a CoS2-NF precursor is prepared according to the preparation method of Example 1. Then, the Ru component is loaded onto the surface of CoS2-NF by impregnation reduction to obtain the Ru / CoS2-NF heterostructure electrode. The remaining electrolytic cell structure and testing conditions are the same as in Example 1.

[0043] The electrochemical performance of Ru / CoS2-NF was tested. In a 1.0 M KOH electrolyte, the Ru / CoS2-NF heterostructure electrode exhibited good alkaline hydrogen evolution performance at 10 mA cm⁻¹. -2 The overpotential at the current density is approximately 65 mV. When used as a cathode in an alkaline decoupled electrocatalytic decomposition system for hydrogen sulfide, the system current density reaches approximately 55 mA cm⁻¹ at a battery voltage of 2.0 V. -2 It retains approximately 90% of its initial current density after 8 hours of continuous operation; the hydrogen Faraday efficiency is approximately 94.5%.

[0044] Example 7 The difference from Example 1 is that in this example, the cathode electrode is a Pt-supported WS2 nickel foam (Pt / WS2-NF) heterostructure electrode, and the anolyte contains 1.0 × 10⁻⁶ N·m³ / h. -3 M EDTA-Fe 2+ / EDTA-Fe 3+ A 0.1 M KOH solution of a redox couple. Specifically, the cathode electrode preparation steps are as follows: First, a WS2-NF precursor is prepared according to the preparation method of Example 1. Then, the Pt component is loaded onto the surface of WS2-NF by impregnation reduction to obtain a Pt / WS2-NF heterostructure electrode. The remaining electrolytic cell structure and testing conditions are the same as in Example 1.

[0045] Electrochemical performance of Ru / CoS2-NF was tested. In 1.0 M KOH electrolyte, the Pt / WS2 heterostructure electrode exhibited good alkaline hydrogen evolution performance at 10 mA cm⁻¹. -2 The overpotential at the current density is approximately 72 mV. When used as a cathode in an alkaline decoupled electrocatalytic decomposition system for hydrogen sulfide, the system current density reaches approximately 5 mAcm⁻¹ at a battery voltage of 2.0 V. -2 It retains approximately 89% of its initial current density after 8 hours of continuous operation; the hydrogen Faraday efficiency is approximately 94.0%.

[0046] Example 8 The difference from Example 1 is that the structure of the electrocatalytic device is changed in this example. Specifically, the electrocatalytic reaction is carried out in an electrocatalytic reaction cell. The bipolar plate of the electrocatalytic reaction cell is a nickel plate with parallel flow channels, and a titanium protective mesh is set on the outside of the cathode to prevent particles or bubbles on the electrode surface from clogging the flow channels. The anode is a graphite felt to improve the contact area of ​​the anolyte and the mass transfer efficiency.

[0047] The anolyte was a mixed solution of 0.1 M KOH and 0.5 M K₄[Fe(CN)₆]. A peristaltic pump was used to control the anolyte circulation at a flow rate of 10 mL / min. -1 .

[0048] Under the aforementioned device structure, the hydrogen evolution overpotential of the Ru / Ni3S2-NF cathode in 1.0 M KOH remained at approximately 40.3 mV, indicating that the structural changes did not degrade the intrinsic hydrogen evolution performance of the cathode material. In full-cell testing, this system achieved approximately 210 mA cm⁻¹ at a cell voltage of 2.0 V. - The current density was 2200 ppm; after 8 hours of continuous operation, it maintained approximately 93% of the initial current density; the hydrogen Faraday efficiency remained above 95%, with an average of approximately 96.3%. X-ray diffraction characterization of the obtained sulfur product showed that its main diffraction peaks were consistent with the elemental sulfur standard card, indicating that the decoupling conversion of hydrogen sulfide to hydrogen and elemental sulfur could still be achieved after modifying the device structure.

[0049] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing hydrogen and sulfur by alkaline decoupling electrocatalytic decomposition of hydrogen sulfide, characterized in that: The method includes the following steps: The catholyte and the anolyte containing the reduced redox medium are respectively introduced into the cathode chamber and anode chamber of the electrocatalytic device. Under the action of an applied voltage, hydrogen evolution reaction occurs at the cathode to generate hydrogen gas, and the reduced redox medium is oxidized to the oxidized redox medium at the anode. The anolyte containing the oxidized redox medium is then transported to the reaction unit, where it reacts with hydrogen sulfide to generate elemental sulfur, as well as a mixture of the reduced redox medium and water. The mixture of the reduced redox medium and water is then transported to the anode chamber for recycling.

2. The method according to claim 1, characterized in that: The supporting electrolyte for the catholyte and anolyte is either KOH or NaOH, and the supporting electrolyte for the catholyte and anolyte is the same.

3. The method according to claim 1, characterized in that: The cathode electrode of the electrocatalytic device is a noble metal-supported transition metal sulfide heterostructure electrode; in the noble metal-supported transition metal sulfide heterostructure electrode, the noble metal is one of Ru, Pt, Pd, Ir, and Rh, and the transition metal sulfide is one of Ni3S2, CoS2, FeS2, MoS2, and WS2.

4. The method according to claim 3, characterized in that: The mass content of the noble metal in the noble metal-supported transition metal sulfide heterostructure electrode is 0.01wt% to 20wt%, preferably 0.1wt% to 5wt%.

5. The method according to claim 1, characterized in that: The anode electrode of the electrocatalytic device is one of carbon paper, carbon cloth, graphite sheet, graphite felt, glassy carbon, titanium sheet, or titanium mesh.

6. The method according to claim 1, characterized in that: The redox mediator contains a reversible redox couple, which is selected from one of iron-based complex redox couples and quinone redox couples; the concentration of the redox mediator in the anolyte is 1 × 10⁻⁶. -3 ~2 M.

7. The method according to claim 6, characterized in that: The iron-based complex redox couple includes [Fe(CN)6]. 4- / [Fe(CN)6] 3- EDTA-Fe 2+ / EDTA-Fe 3+ One of them; the quinone redox couple includes one of hydroquinone / benzoquinone and its derivatives.

8. The method according to claim 1, characterized in that: The hydrogen sulfide-containing gas includes one or more of the following: natural gas, shale gas, coalbed methane, refinery gas, biogas, and coke oven gas.

9. An apparatus for the alkaline decoupling electrocatalytic decomposition of hydrogen sulfide to produce hydrogen and sulfur in carrying out the method according to any one of claims 1-8, characterized in that: It includes an electrocatalytic device, a reaction unit, a circulating pump, pipelines, and a product collection unit; The electrocatalytic device includes a cathode chamber, an anode chamber, and an anion exchange membrane for separating the cathode chamber and the anode chamber; The inlet of the reaction unit is connected to the outlet of the anode chamber via a pipeline, and the outlet of the reaction unit is connected to the inlet of the anode chamber via a circulation pump. The anode chamber includes an anode electrode and an anode bipolar plate; The cathode chamber includes a cathode electrode and a cathode bipolar plate; The anode bipolar plate and the cathode bipolar plate are provided with parallel flow channels or serpentine flow channels; The anode electrode is one of carbon paper, carbon cloth, graphite sheet, graphite felt, glassy carbon, titanium sheet, and titanium mesh; The cathode electrode is a noble metal-loaded transition metal sulfide heterostructure electrode.

10. The apparatus according to claim 9, characterized in that: The electrocatalytic device has a flow-type structure.

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