A high-temperature electrochemical method and device for fully decomposing hydrogen sulfide to produce hydrogen and sulfur

Abstract

The present invention discloses a high-temperature electrochemical method and device for fully decomposing hydrogen sulfide to produce hydrogen and sulfur. The method includes the following steps: a gas containing hydrogen sulfide undergoes an electrochemical oxidation reaction at the anode of an electrolytic cell to produce sulfur and protons; the sulfur flows out of the anode chamber of the electrolytic cell in a gaseous state under high temperature conditions and is collected; the protons pass through the solid electrolyte membrane of the electrolytic cell to reach the cathode, and are reduced at the cathode of the electrolytic cell to produce hydrogen; the solid electrolyte membrane is a high-temperature proton conductor, allowing protons to pass from the anode to the cathode under high temperature conditions. The present invention converts hydrogen sulfide into high-value-added products through electrochemical means, achieving the treatment and resource utilization of toxic gases. Compared with traditional electrochemical methods, water is not required as an absorption medium for hydrogen sulfide, the hydrogen sulfide decomposition efficiency is high, and the resulting sulfur product has high purity.

Description

Technical Field

[0001] The invention relates to a high-temperature electrochemical method and device for fully decomposing hydrogen sulfide to produce hydrogen and sulfur, belonging to the field of harmful gas treatment. Background Art

[0002] Hydrogen sulfide is a highly toxic and corrosive gas that is widely present in industrial exhaust emissions, biogas, natural gas, and shale gas. High concentrations of hydrogen sulfide not only cause significant environmental pollution but also pose a serious threat to human health.

[0003] At present, the commonly used methods for treating hydrogen sulfide include alkaline solution absorption method, high temperature absorption method and high temperature catalytic conversion method. However, secondary pollution, high energy consumption, low conversion rate and low yield have seriously restricted the development of the above methods. In order to overcome the above shortcomings, researchers have developed photocatalytic and room temperature electrochemical hydrogen sulfide decomposition methods, which can achieve the goal of decomposing hydrogen sulfide into hydrogen and sulfur at room temperature and pressure. However, the solid sulfur produced by the above two methods easily adheres to the photocatalyst or electrode, causing the problem of photocatalyst and electrocatalyst poisoning, which will seriously restrict the development of the above two methods. Therefore, it is of great significance to develop a new method for treating hydrogen sulfide that is efficient, green and resistant to poisoning. Summary of the Invention

[0004] The present invention aims to provide a high-temperature electrochemical method and apparatus for fully decomposing hydrogen sulfide to produce hydrogen and sulfur. This method can simultaneously convert hydrogen sulfide into high-value-added products (hydrogen and sulfur), thereby achieving harmless treatment of harmful mixed gases. The method has high treatment efficiency and significant results.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] In one aspect, the present invention provides an electrocatalytic device for fully decomposing hydrogen sulfide to produce hydrogen and sulfur. The device comprises an electrolytic cell, wherein a solid electrolyte membrane is provided in the electrolytic cell, and the solid electrolyte membrane separates the electrolytic cell into an anode chamber and a cathode chamber;

[0007] The anode chamber comprises an anode catalyst layer, an anode gas diffusion layer and an anode bipolar plate stacked in sequence; the anode chamber has an anode gas inlet and an anode gas outlet;

[0008] The cathode chamber comprises a cathode catalyst layer, a cathode gas diffusion layer and a cathode bipolar plate stacked in sequence; and the cathode chamber has a cathode gas outlet.

[0009] In the above technical solution, preferably, it further comprises a voltage applying device, wherein the voltage applying device is connected to the cathode and anode circuits of the electrocatalytic device respectively.

[0010] In the above technical solution, preferably, the thickness of the solid electrolyte membrane is 0.5-20 μm, more preferably 1-10 μm;

[0011] In the solid electrolyte membrane, the electrolyte is a proton conductive solid electrolyte, and the proton conductive solid electrolyte is at least one of LiSO4, CsHSO4, RbHSO4, SrCeO3, BaCeO3, silicotungstic acid and phosphomolybdic acid.

[0012] In the above technical solution, preferably, the anode catalyst layer and the cathode catalyst layer are both porous structures, and the pores of the porous structures are 0.5-100 μm;

[0013] The catalyst in the cathode catalyst layer is at least one of Pt / C, MoS2, WS2, NiS, FeS, CoS, MoC2 and WC;

[0014] The catalyst in the anode catalyst layer is at least one of Pd, RuO2, IrO2, MoS2, NiS, FeS, CoS, and MoNiS.

[0015] In the above technical solution, preferably, the anode gas diffusion layer and the cathode gas diffusion layer are made of one of porous carbon, porous foam titanium and porous foam nickel;

[0016] The pores of the porous carbon, porous foam titanium and porous foam nickel are all 10-100 μm.

[0017] In the above technical solution, preferably, the anode bipolar plate and the cathode bipolar plate are both made of one of titanium plates and titanium alloy plates.

[0018] Another aspect of the present invention provides a high-temperature electrochemical method for producing hydrogen and sulfur by completely decomposing hydrogen sulfide. The method uses the above-mentioned device and comprises the following steps:

[0019] The gas containing hydrogen sulfide is catalytically oxidized in the anode chamber of the electrocatalytic device to produce sulfur and protons. The protons pass through the solid electrolyte membrane and are catalytically reduced in the cathode chamber of the electrocatalytic device to produce hydrogen.

[0020] The gas containing hydrogen sulfide in the electrocatalytic device enters from the anode gas inlet, and the purified gas and the generated high-temperature sulfur gas are discharged from the anode gas outlet; in the electrocatalytic device, the generated hydrogen is discharged from the cathode gas outlet.

[0021] In the above technical solution, preferably, the operating temperature of the anode chamber and the cathode chamber are independently 450-900°C, more preferably 500-850°C.

[0022] In the above technical solution, preferably, the working current density of the anode chamber and the cathode chamber is independently 20-1500 mA / cm 2 .

[0023] In the above technical solution, preferably, the applied voltage is a DC voltage.

[0024] In the above technical solution, preferably, the volume concentration of hydrogen sulfide in the gas containing hydrogen sulfide is 5-100%.

[0025] In the above technical solution, preferably, the flow rate of the gas containing hydrogen sulfide is 0.5-500 ml / min, more preferably 2-300 ml / min.

[0026] The beneficial effects of the present invention are:

[0027] (1) The present invention provides a high-temperature electrochemical conversion method for hydrogen sulfide-containing gas, wherein hydrogen sulfide is oxidized to sulfur at the anode and proton reduction is performed at the cathode to produce hydrogen. The Faraday efficiency of hydrogen sulfide electrolysis in this system is not less than 95%, and the conversion rate of hydrogen sulfide is not less than 80%.

[0028] (2) The high-temperature electrochemical conversion treatment device for hydrogen sulfide-containing gas provided by the present invention includes a bipolar plate, a gas diffusion layer, a catalyst cathode layer, a solid electrolyte membrane, and a catalyst anode layer. The entire device can achieve complete decomposition of hydrogen sulfide. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of a high-temperature electrochemical conversion treatment device for hydrogen sulfide-containing gas in Example 1 of the present invention;

[0030] In the figure: 001, cathode chamber, 002, anode chamber, 003, solid electrolyte membrane, 004, DC power supply, 005, cathode catalyst layer, 006, anode catalyst layer, 007, cathode gas diffusion layer, 008, anode gas diffusion layer, 009, cathode bipolar plate, 010, anode bipolar plate;

[0031] Figure 2 This is a schematic diagram of the high-temperature electrochemical conversion treatment reaction process of hydrogen sulfide-containing gas in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0033] Unless otherwise specified, the raw materials and catalysts in the examples of the present invention were purchased from commercial sources.

[0034] Example 1 Electrocatalytic Device for Fully Decomposing Hydrogen Sulfide to Produce Hydrogen and Sulfur

[0035] See also Figure 1 The device includes an electrolytic cell, in which a solid electrolyte membrane 003 is provided. The solid electrolyte membrane 003 separates the electrolytic cell into a cathode chamber 001 and an anode chamber 002; the anode chamber 002 includes an anode catalyst layer 006, an anode gas diffusion layer 008 and an anode bipolar plate 010 stacked in sequence; the anode chamber 002 has an anode gas inlet and an anode gas outlet; the cathode chamber 001 includes a cathode catalyst layer 005, a cathode gas diffusion layer 007 and a cathode bipolar plate 009 stacked in sequence; the cathode chamber 001 has a cathode gas outlet; the solid electrolyte membrane 003 is provided between the cathode catalyst layer 005 and the anode catalyst layer 006; a DC power supply 004 provides energy to the electrolytic device through the bipolar plates of the anode chamber 002 and the cathode chamber 001.

[0036] See also Figure 2 The gas containing hydrogen sulfide enters from the anode chamber 002, passes through the anode gas diffusion layer 008, and undergoes a high-temperature catalytic oxidation reaction on the anode catalyst layer 006 to generate sulfur and protons. The high-temperature gaseous sulfur, purified gas and unreacted hydrogen sulfide gas are discharged from the anode chamber outlet. The discharged unreacted gas can re-enter the anode chamber inlet for a cyclic reaction; the protons generated in the anode chamber 002 pass through the solid electrolyte membrane 003 and reach the cathode catalyst layer 005, and undergo a high-temperature catalytic reduction reaction on the cathode catalyst layer 005 to generate hydrogen. The hydrogen passes through the cathode gas diffusion layer 007 and is discharged from the cathode chamber outlet.

[0037] The entire treatment process has a low waste gas and waste liquid yield, and only requires an electrolysis device to treat the harmful gas hydrogen sulfide. The equipment is simple and low-cost, and the treatment efficiency is high.

[0038] Example 2 Simulating the high-temperature electrochemical decomposition of hydrogen sulfide in natural gas

[0039] See also Figure 2 In this embodiment, the electrolysis reaction is carried out in an electrochemical reactor, with sulfur produced in the anode chamber and hydrogen produced in the cathode chamber. The cathode and anode chambers are separated by a 1μm-thick phosphomolybdic acid solid electrolyte membrane coated with a catalyst layer. The cathode is coated with a porous Pt / C catalyst coating with a pore size of approximately 10μm, while the anode is coated with a porous IrO2 catalyst coating with a pore size of approximately 15μm. Both sides of the catalyst are flanked by 20μm-thick titanium foam diffusion layers, which are surrounded by titanium alloy bipolar plates. A high-temperature-resistant gasket is placed between the bipolar plates and the diffusion layer.

[0040] A mixed gas (CH4:H2S=80%:20%, V / V) was introduced into the electrolytic cell at the anode chamber gas inlet at a flow rate of 25 ml / min to carry out the electrochemical reaction. Reaction conditions: temperature 450°C, current density 100 mA / cm2 After applying the voltage and reacting for 30 seconds, a large number of bubbles were generated at the cathode and collected using the drainage method. The gas at the anode outlet cooled and became a yellow, viscous liquid, which solidified into a yellow solid, which was then dried and weighed.

[0041] Throughout the process, hydrogen was generated at a rate of 255 ml / h, and the dried sulfur weighed 0.32 g. The reaction yielded 11.4 mmol of hydrogen and 11.3 mmol of elemental sulfur from a feed of 13.4 mmol of hydrogen sulfide. The Ladaic efficiency of hydrogen sulfide electrolysis was nearly 98%, and the hydrogen sulfide conversion was 85%.

[0042] Example 3 Simulation of high-temperature electrochemical decomposition of hydrogen sulfide in natural gas

[0043] The difference from Example 2 is that:

[0044] The cathode catalyst layer is a FeS porous layer with a pore size of 0.5 μm, the anode catalyst layer is a NiS porous layer with a pore size of 100 μm, and the porous carbon is a diffusion layer with a layer thickness of 10 μm.

[0045] The Radic efficiency of hydrogen sulfide electrolysis is nearly 97%, and the hydrogen sulfide conversion rate is 81%.

[0046] Example 4 Simulation of high-temperature electrochemical decomposition of hydrogen sulfide in natural gas

[0047] The difference from Example 2 is that:

[0048] The cathode catalyst layer is a MoS2 porous layer with a pore size of 50 μm, the anode catalyst layer is a MoNiS porous layer with a pore size of 30 μm, and the porous carbon is a diffusion layer with a layer thickness of 100 μm.

[0049] The Radius efficiency of hydrogen sulfide electrolysis is nearly 96%, and the hydrogen sulfide conversion rate is 82%.

[0050] Example 5 Simulating the high-temperature electrochemical decomposition of hydrogen sulfide in natural gas

[0051] The difference from Example 2 is that:

[0052] The flow rate of the mixed gas (CH4:H2S=80%:20%, V / V) is 125 ml / min, the operating temperature of the electrolysis device is 650°C, and the operating current density is 500 mA / cm 2 , the solid electrolyte is SrCeO3 and the thickness is 1.5μm.

[0053] The Radius efficiency of hydrogen sulfide electrolysis is nearly 95%, and the hydrogen sulfide conversion rate is 83%.

[0054] Example 6 Simulation of high-temperature electrochemical decomposition of hydrogen sulfide in natural gas

[0055] The difference from Example 2 is that:

[0056] The ratio of the mixed gas CH4:H2S is 60%:40% (V / V), the flow rate is 300ml / min, and the operating current density is 1000mA / cm 2 The operating temperature of the electrolysis device is 850°C, the solid electrolyte is SrCeO3 with a thickness of 1.5μm, and the bipolar plate is a titanium plate.

[0057] The Radius efficiency of hydrogen sulfide electrolysis is nearly 96%, and the hydrogen sulfide conversion rate is 81%.

[0058] Example 7 Simulating the high-temperature electrochemical decomposition of hydrogen sulfide in natural gas

[0059] The difference from Example 2 is that:

[0060] The ratio of the mixed gas CH4:H2S is 60%:80% (V / V), and the operating current density is 1500mA / cm 2 The operating temperature of the electrolysis device is 900℃, the solid electrolyte is BaCeO3 with a thickness of 10μm, and the bipolar plate is a titanium plate.

[0061] The Radius efficiency of hydrogen sulfide electrolysis is nearly 97%, and the hydrogen sulfide conversion rate is 80%.

[0062] Example 8 Simulating the high-temperature electrochemical decomposition of hydrogen sulfide in natural gas

[0063] The difference from Example 2 is that:

[0064] The ratio of the mixed gas CH4:H2S is 60%:80% (V / V), and the operating current density is 300mA / cm 2 The operating temperature of the electrolysis device is 500℃, the solid electrolyte is RbHSO4, and the thickness is 2μm.

[0065] The Radius efficiency of hydrogen sulfide electrolysis is nearly 95%, and the hydrogen sulfide conversion rate is 81%.

[0066] The parameters used in Examples 2 to 8 are listed in Table 1. The results obtained in Examples 2 to 8 are listed in Table 2.

[0067] Table 1 Parameters used in Examples 2 to 8

[0068]

[0069]

[0070] Table 2 Results obtained from treating simulated natural gas at a gas flow rate of 5 ml / min in Examples 2 to 8

[0071]

[0072]

[0073] Where a: hydrogen sulfide conversion rate is: b: Faradaic efficiency of hydrogen sulfide electrolysis: Note: The Faraday constant is 96485 coulombs per mole;

[0074] As can be seen from Examples 2 to 8 above, the method provided by the present invention can decompose hydrogen sulfide into sulfur and hydrogen at high temperatures, thereby recovering and utilizing harmful gases. The resulting product has a high yield and high product value.

[0075] The above descriptions are merely several embodiments of the present invention and do not constitute any form of limitation to the present invention. Although the present invention is disclosed as above in terms of preferred embodiments, they are not intended to limit the present invention. Any technician familiar with the present profession who, without departing from the scope of the technical solution of the present invention, makes slight changes or modifications using the technical contents disclosed above are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A high-temperature electrochemical method for producing hydrogen and sulfur by completely decomposing hydrogen sulfide, characterized in that: The method uses the following apparatus: the apparatus comprises an electrolytic cell, wherein a solid electrolyte membrane is provided in the electrolytic cell, and the solid electrolyte membrane separates the electrolytic cell into an anode chamber and a cathode chamber; The anode chamber comprises an anode catalyst layer, an anode gas diffusion layer and an anode bipolar plate stacked in sequence; the anode chamber has an anode gas inlet and an anode gas outlet; The cathode chamber comprises a cathode catalyst layer, a cathode gas diffusion layer and a cathode bipolar plate stacked in sequence; the cathode chamber has a cathode gas outlet; The method comprises the following steps: The gas containing hydrogen sulfide is catalytically oxidized in the anode chamber of the electrocatalytic device to produce sulfur and protons, and the protons pass through the solid electrolyte membrane and are catalytically reduced in the cathode chamber of the electrocatalytic device to produce hydrogen; In the solid electrolyte membrane, the electrolyte is a proton conductive solid electrolyte, and the proton conductive solid electrolyte is at least one of SrCeO3, BaCeO3, silicotungstic acid and phosphomolybdic acid; The operating temperature of the anode chamber and the cathode chamber is independently 450-900°C; The operating current density of the anode chamber and cathode chamber is independently 100-1500 mA / cm 2 .

2. The high-temperature electrochemical method for producing hydrogen and sulfur by fully decomposing hydrogen sulfide according to claim 1, characterized in that: The thickness of the solid electrolyte separator is 0.5 μm-20 μm.

3. The high-temperature electrochemical method for producing hydrogen and sulfur by fully decomposing hydrogen sulfide according to claim 1, characterized in that: The anode catalyst layer and the cathode catalyst layer are both porous structures, and the pores of the porous structures are 0.5-100 μm; The catalyst in the cathode catalyst layer is at least one of Pt / C, MoS2, WS2, NiS, FeS, CoS, MoC2 and WC; The catalyst in the anode catalyst layer is at least one of Pd, RuO2, IrO2, MoS2, NiS, FeS, CoS, and MoNiS.

4. The high-temperature electrochemical method for producing hydrogen and sulfur by fully decomposing hydrogen sulfide according to claim 1, characterized in that: The anode gas diffusion layer and the cathode gas diffusion layer are made of one of porous carbon, porous foam titanium and porous foam nickel; The pores of the porous carbon, porous foam titanium and porous foam nickel are all 10-100 μm.

5. The high-temperature electrochemical method for producing hydrogen and sulfur by fully decomposing hydrogen sulfide according to claim 1, characterized in that: The anode bipolar plate and the cathode bipolar plate are both titanium plates or titanium alloy plates.

6. The high-temperature electrochemical method for producing hydrogen and sulfur by fully decomposing hydrogen sulfide according to claim 1, characterized in that: The volume concentration of hydrogen sulfide in the hydrogen sulfide-containing gas is 5-100%.

7. The high-temperature electrochemical method for producing hydrogen and sulfur by fully decomposing hydrogen sulfide according to claim 1, characterized in that: The flow rate of the gas containing hydrogen sulfide is 0.5-500 ml / min.

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