Method for coating a blade electrode, blade electrode, sliding arc plasma reactor, and method for plasma conversion of methane

Abstract

The present invention relates to the field of plasma, and discloses a method for coating a blade electrode, a blade electrode, a sliding arc plasma reactor, and a method for plasma conversion of methane. The method includes: using atomic layer deposition to apply a coating material to the blade electrode in the sliding arc plasma reactor to obtain a coating layer containing at least two single-layer atomic layer deposition metal oxide films arranged in layers on the surface of the blade electrode, the coating layer being a semiconductor material. Among them, in the blade electrode, the applied coating material makes the semiconductor materials of the coating layer I and the coating layer II different. The coating layer I is the middle region of the blade surface, and the coating layer II is the two side regions of the blade surface. The solution provided by the present invention modifies the blade electrode by coating a dielectric layer on the surface of the blade electrode, which can directly and efficiently convert methane into ethylene, reduce energy consumption, and effectively inhibit carbon deposition.

Description

Technical Field

[0001] The present invention relates to the field of plasma, and particularly to a method for coating a blade electrode, a blade electrode, a sliding arc plasma reactor, and a method for plasma conversion of methane. Background Art

[0002] The research on plasma methane conversion technology in China started in the 1980s and gradually formed patent technologies since 2000.

[0003] CN1360008A discloses a method for preparing gasoline by plasma conversion of methane and carbon dioxide. In this method, CO2 is added as another reactant and the main product is gasoline. CN1552680A discloses a method for preparing acetylene by thermal plasma cracking of methane-containing gas, mainly using methane as the raw material and acetylene as the main by-product. CN100999432A discloses a method for ionic liquid-catalyzed plasma conversion of methane to C2 hydrocarbons. CN101734620A discloses a method for producing hydrogen from rich methane gas by plasma.

[0004] Southwest Research and Design Institute of Chemical Industry has announced a series of patent technologies for plasma cracking of methane, mainly for the development of processes for plasma conversion of methane to produce carbon black or acetylene and hydrogen, with more emphasis on process design and optimization.

[0005] Tsinghua University, Taiyuan University of Technology and Xinjiang Tianye Group jointly developed a process for plasma cracking of coal to produce acetylene, mainly using coal as the raw material and natural gas as an auxiliary to produce acetylene and hydrogen, and its working gas is hydrogen.

[0006] Zhejiang University mainly developed a method for plasma on-line coke cleaning, which can introduce CO2 or H2 to remove carbon deposition on the electrode surface. It also developed a method for producing acetylene by rotating arc plasma cracking of methane, in which the working gas rotates into the discharge gap and is driven by an external magnetic field at the same time, and millisecond-level cracking occurs.

[0007] Through the analysis and summary of foreign literature patents, it is found that the method for converting methane to olefins was initially mainly based on the technology of arc cracking of methane, and its main product was acetylene. Since carbon deposition was easily generated to form carbon black during the process, carbon black was used as a by-product.

[0008] Other researchers found that the product distribution can be adjusted by changing the inlet gas flow rate or adding inert gas. This technology has been industrialized abroad, including four processes: HUELS method, AVCO method, Du Pont method and Romanian method.

[0009] Through literature comparison, it is found that when using an electric arc to generate high temperature for cracking natural gas to produce acetylene, the electrical energy utilization rate is low. For every 1 ton of acetylene produced, about 13,900 kWh of electrical energy is consumed, accounting for more than 50% of the cost. Therefore, changing the reactor structure to achieve the purpose of energy conservation and consumption reduction is one of the key points of innovation in foreign patent literature.

[0010] On the basis of the above technology, a series of "thermal" plasma technologies and "cold" plasma technologies have been gradually developed. By changing the energy generation form, the energy consumption is reduced, and a catalyst is added for coupling to directionally convert methane into the target product. Currently, this process is still under exploration. There are pilot plants, but no industrial plants have been reported.

[0011] To sum up, for the research on the conversion of natural gas plasma to ethylene, most of them adopt the form of plasma catalytic coupling. Dielectric barrier discharge mainly produces ethane, and the products of thermal plasma or sliding arc plasma are mainly acetylene. Currently, there is no plasma form that can directly produce ethylene.

[0012] In addition, CN106925086A discloses a plasma degradation treatment device for organic waste gas. The plasma treatment device is a plasma reactor, including a reactor cylinder body, a gas inlet at the top of the reactor cylinder body, a gas outlet at the bottom of the reactor, a plasma discharge electrode located in the reactor cylinder body, and a power supply interface for supplying power to the plasma discharge device; an energy utilization device for expanding the area and length of the sliding arc is arranged on the reactor cylinder body. The energy utilization device is an arc-expanding rod, an arc-expanding plate or a combination of the two. However, when this reactor is used for the directional conversion of methane, the methane conversion rate is low and the olefin selectivity is low. Summary of the Invention

[0013] The purpose of the present invention is to overcome the defect of low selectivity in the conversion of methane to ethylene existing in the existing plasma technology.

[0014] To achieve the above purpose, the first aspect of the present invention provides a method for coating a blade electrode, the method comprising: using atomic layer deposition to apply a coating material to the blade electrode in a sliding arc plasma reactor to obtain a coating layer containing at least two single-layer atomic layer deposition metal oxide films stacked on the surface of the blade electrode, the coating layer being a semiconductor material, wherein, in the blade electrode, the applied coating material makes the semiconductor materials of coating layer I and coating layer II different in type, coating layer I is the middle area of the blade surface, and coating layer II is the two-side areas of the blade surface;

[0015] Wherein, the applied coating material makes the dielectric constant of the semiconductor material of coating layer I 6 - 70 C higher than that of the semiconductor material of coating layer II 2 / (N·M 2 )。

[0016] The second aspect of the present invention provides a blade electrode obtained by coating using the method described in the first aspect above.

[0017] The third aspect of the present invention provides a sliding arc plasma reactor, which has a coaxial jacketed structure, and the reactor includes:

[0018] An inner cylinder, on which a reactor inlet, a side-line feed inlet, a lower reaction zone, and a product outlet are respectively provided;

[0019] An outer cylinder, which is nested outside the inner cylinder, and a heat transfer medium inlet and a heat transfer medium outlet are respectively provided on the outer cylinder;

[0020] A blade electrode sliding arc generator, which includes a gas nozzle, a blade electrode, and a base;

[0021] Wherein, the side-line feed inlet passes through the outer cylinder and leads into the inner cylinder, so that the reaction gas can enter the inner cylinder through the side-line feed inlet; at least two symmetrically distributed blade electrodes are provided on the base of the blade electrode sliding arc generator, so that a discharge area can be formed between the blade electrodes; the gas nozzle is provided on the base, so that the raw material gas can enter the inner cylinder from the reactor inlet through the gas nozzle;

[0022] Wherein, the blade electrode is the blade electrode described in the second aspect above.

[0023] The fourth aspect of the present invention provides a method for converting methane by plasma, which is implemented in the sliding arc plasma reactor described in the third aspect above. The method includes:

[0024] Under plasma discharge conditions, a raw material gas containing methane is introduced into the inner cylinder of the sliding arc plasma reactor through the reactor inlet and the gas nozzle, and a reaction gas containing hydrogen is introduced into the inner cylinder of the sliding arc plasma reactor through the side-line feed inlet, so that the raw material gas sequentially passes through the discharge area formed by the blade electrodes and the lower reaction zone to carry out the methane conversion reaction, and the product obtained after the reaction is led out of the sliding arc plasma reactor through the product outlet; and, by continuously introducing a heat transfer medium into the outer cylinder of the sliding arc plasma reactor from the heat transfer medium inlet and leading out the heat transfer medium from the heat transfer medium outlet, the temperature required for the sliding arc plasma reactor is maintained.

[0025] Compared with the prior art, the solution provided by the present invention has at least the following advantages:

[0026] (1) The solution provided by the present invention modifies the blade electrode by coating a dielectric layer on the surface of the blade electrode, thereby weakening the arc energy, reducing the temperature of the plasma field, and further enabling the direct conversion of methane into ethylene. This solution can effectively simplify the process flow of methane conversion to olefins, directly and efficiently convert methane into ethylene under the action of an electric field, improve the discharge efficiency, and prevent electrode ablation.

[0027] (2) The solution provided by the present invention can achieve the continuous and stable progress of the reaction at a relatively high reactant conversion efficiency, reduce energy consumption, effectively inhibit carbon deposition, and compared with the traditional methane-to-olefins process, there is no CO2 generation, the ethylene yield is high, and there is no risk of combustion and explosion, which is safer and more environmentally friendly.

[0028] Other features and advantages of the present invention will be described in detail in the following specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of a preferred specific implementation of the sliding arc plasma reactor provided by the present invention.

[0030] Figure 2 It is a schematic diagram of the cutting edge surface of the blade electrode obtained by coating using the method provided by the present invention.

[0031] DESCRIPTION OF THE REFERENCE NUMERALS

[0032] SPECIFIC IMPLEMENTATION MODE

[0033] In the ranges disclosed herein, the endpoints and any values are not limited to the exact range or value, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0034] As described above, the first aspect of the present invention provides a method for coating a blade electrode, the method comprising: applying a coating material to the blade electrode in a sliding arc plasma reactor by atomic layer deposition to obtain a coating containing at least two single-layer atomic layer deposition metal oxide films stacked on the surface of the blade electrode, the coating being a semiconductor material, wherein in the blade electrode, the applied coating material makes the semiconductor materials of coating I and coating II different, coating I being the middle region of the cutting edge surface, and coating II being the regions on both sides of the cutting edge surface.

[0035] Among them, the applied coating material makes the dielectric constant of the semiconductor material of the coating layer I 6 - 70 C higher than that of the semiconductor material of the coating layer II 2 / (N·M 2 ).

[0036] Preferably, the applied coating material makes the dielectric constant of the semiconductor material of the coating layer I 10 - 25 C higher than that of the semiconductor material of the coating layer II 2 / (N·M 2 ). The inventor found that in a more preferred case, the coating layer obtained by the present invention can not only improve the efficiency of methane conversion to ethylene, but also reduce the energy consumption.

[0037] Preferably, the coating material is an organic compound containing a metal element.

[0038] Preferably, the semiconductor material is a metal oxide.

[0039] More preferably, the coating layer I is selected from at least one of ZrO2, HfO2, TiO2, La2O3, Ta2O5, and the coating layer II is selected from at least one of Al2O3, SnO2, ZnO, Y2O3.

[0040] In the present invention, the dielectric constants of the metal oxides are respectively:[[]]

[0041] ZrO2: 22 - 25 C 2 / (N·M 2 ), HfO2: 21 - 25 C 2 / (N·M 2 ), TiO2: 80 - 86 C 2 / (N·M 2 ), La2O3: 30 C 2 / (N·M 2 ), Ta2O5: 26 C 2 / (N·M 2 ), Al2O3: 10 C 2 / (N·M 2 ), SnO2: 12 - 16 C 2 / (N·M 2 ), ZnO: 8 - 12 C 2 / (N·M 2 ), Y2O3: 15 C 2 / (N·M 2 ).

[0042] Preferably, the step of coating the blade electrode in the sliding arc plasma reactor by atomic layer deposition method includes: in the atomic layer deposition device,

[0043] (1) In the presence of a carrier gas, open the ALD valve of the metal source tank, and the coating material in the metal source tank enters the reaction chamber containing oxygen, so that the coating material reacts with oxygen on the surface of the blade electrode in the reaction chamber to form a single atomic layer deposited metal oxide film;

[0044] (2) Repeat step (1) to obtain the coating. Each repetition forms a single atomic layer deposited metal oxide film, and the coating thickness is adjusted by controlling the number of repetitions;

[0045] (3) Use two kinds of the coating materials to perform repeated operations through the above steps (1) to (2) in the areas of the coating I and the coating II respectively to form two coatings.

[0046] In the present invention, when performing the coating operation on the area of the coating I, for example, the area of the coating II can be shielded first; similarly, when performing the coating operation on the area of the coating II, for example, the area of the coating I can be shielded first, so as to achieve coating different materials in different areas.

[0047] Preferably, in step (1), the temperature of the metal source tank is 140 - 160 °C, the temperature of the reaction chamber is 50 - 400 °C, and the temperature of the transportation pipeline and the ALD valve is 180 - 200 °C.

[0048] Preferably, in step (1), evacuate the reaction chamber and the transportation pipeline to a pressure of 10 - 200 Pa.

[0049] Preferably, in step (1), the flow rate of the carrier gas is 10 - 200 sccm.

[0050] Preferably, in step (1), the opening time of the ALD valve is 50 - 2000 ms.

[0051] Preferably, in step (1), it further includes cleaning the reaction chamber by introducing an inert gas pulse.

[0052] More preferably, the cleaning time is 1 - 200 s.

[0053] In the present invention, in each coating, the number of repetitions of forming a single atomic layer deposited metal oxide film is 200 - 600.

[0054] In the present invention, as Figure 2As shown, the sum of the area of the coating I and the area of the coating II is the total area of the blade surface. Preferably, the area of the coating I accounts for 1 / 3 - 1 / 2 of the total area of the blade surface. The inventors found that in the preferred case, the coating obtained in the present invention can more effectively regulate the arc energy, thereby improving the efficiency of directly converting methane into ethylene.

[0055] In the present invention, after the blade electrode in the sliding arc plasma reactor is coated by atomic layer deposition, the blade electrode is calcined in a muffle furnace at 400 - 600 °C.

[0056] The method for coating the blade electrode provided by the present invention modifies the blade electrode by coating a dielectric layer on the surface of the blade electrode, thereby weakening the arc energy and reducing the plasma field temperature, so that methane is directly converted into ethylene; this method can effectively simplify the process flow of converting methane into olefins, directly and efficiently convert methane into ethylene under the action of an electric field, and can improve the discharge efficiency and prevent electrode ablation.

[0057] According to a preferred embodiment, the steps of coating the blade electrode in the sliding arc plasma reactor by atomic layer deposition include: in the atomic layer deposition device,

[0058] (1) Place the coating material in the metal source tank and place the blade electrode to be coated in the reaction chamber; [[ID=,14]]

[0059] (2) Heat the metal source tank, the reaction chamber, the transport pipeline and the ALD valve. The temperature of the metal source tank is 140 - 160 °C, the temperature of the reaction chamber is 50 - 400 °C, the temperature of the transport pipeline and the ALD valve is 180 - 200 °C, and evacuate the reaction chamber and the transport pipeline to a pressure of 10 - 200 Pa;

[0060] (3) Open the carrier gas of the metal source tank, and the flow rate of the carrier gas is 10 - 200 sccm;

[0061] (4) Open the ALD valve of the metal source tank, and the opening time of the ALD valve is 50 - 2000 ms, so that the coating material enters the reaction chamber, and introduce oxygen to make the coating material react with oxygen on the surface of the blade electrode in the reaction chamber and form a single-layer atomic layer deposited metal oxide film;

[0062] (5) Clean the reaction chamber by introducing an inert gas pulse, and the cleaning time is 1 - 200 s;

[0063] (6) Repeat steps (1) to (5) to obtain the coating. Each repetition forms a single atomic layer deposited metal oxide film, and the coating thickness is adjusted by controlling the number of repetitions.

[0064] (7) Use two of the above coating materials to repeat the above steps (1) to (6) in the regions of the first coating and the second coating respectively to form two coatings.

[0065] In a preferred embodiment, the method provided by the present invention can better coat the blade electrode by atomic layer deposition, and the obtained coating can more effectively adjust the arc energy, thereby improving the efficiency of directly converting methane into ethylene.

[0066] As described above, the second aspect of the present invention provides a blade electrode obtained by coating with the method described in the first aspect above.

[0067] As described above, the third aspect of the present invention provides a sliding arc plasma reactor, which has a coaxial jacketed structure, and the reactor includes:

[0068] An inner cylinder, on which a reactor inlet, a side-line feed inlet, a lower reaction zone and a product outlet are respectively arranged;

[0069] An outer cylinder, which is nested outside the inner cylinder, and a heat transfer medium inlet and a heat transfer medium outlet are respectively arranged on the outer cylinder;

[0070] A blade electrode sliding arc generator, which includes a gas nozzle, a blade electrode and a base;

[0071] Among them, the side-line feed inlet passes through the outer cylinder and leads into the inner cylinder, so that the reaction gas can enter the inner cylinder through the side-line feed inlet; at least two of the blade electrodes are symmetrically distributed on the base of the blade electrode sliding arc generator, so that a discharge region can be formed between the blade electrodes; the gas nozzle is arranged on the base, so that the raw material gas can enter the inner cylinder from the reactor inlet through the gas nozzle;

[0072] Among them, the blade electrode is the blade electrode described in the second aspect above.

[0073] In the present invention, the symmetric distribution is symmetrically distributed with respect to the central vertical axis of the base. The installation position of the blade electrode needs to ensure that it does not affect the discharge.

[0074] In the present invention, there are no specific limitations on the shape and material of the base, which can be circular or various other shapes capable of achieving the aforementioned invention objectives of the present invention, and can be an insulating material or various other materials capable of achieving the aforementioned invention objectives of the present invention.

[0075] Preferably, 2 or 6 of the blade electrodes are symmetrically distributed on the base.

[0076] According to a preferred specific embodiment, 2 of the blade electrodes are symmetrically distributed on the base of the blade electrode sliding arc generator.

[0077] Preferably, the material forming the blade electrode is a conductive material.

[0078] More preferably, the conductive material is selected from at least one of 316L stainless steel, tungsten cerium alloy, copper, and copper tungsten alloy. The material forming the blade electrode can also be other conductive materials with high temperature resistance and arc corrosion resistance.

[0079] Preferably, a gas nozzle is provided at the center of the base of the blade electrode sliding arc generator, and the gas nozzle communicates with the intake pipeline at the reactor inlet.

[0080] In the present invention, there are no specific limitations on the setting of the gas nozzle. One gas nozzle can be provided at the center of the base or multiple gas nozzles can be symmetrically provided on the base. Preferably, one gas nozzle is provided at the center of the base.

[0081] Preferably, the ratio relationship between the length L1 of the blade electrode and the diameter D1 of the inner cylinder is: L1:D1 = 1:1 - 3, more preferably L1:D1 = 1:1 - 2, and further preferably L1:D1 = 1:1 - 1.5.

[0082] In the present invention, the units of both the length L1 of the blade electrode and the diameter D1 of the inner cylinder can be mm.

[0083] Preferably, the ratio relationship between the length L1 of the blade electrode and the length L2 of the inner cylinder is: L1:L2 = 1:1.5 - 6, more preferably L1:L2 = 1:2 - 5, and further preferably L1:L2 = 1:2 - 3.

[0084] In the present invention, the units of both the length L1 of the blade electrode and the length L2 of the inner cylinder can be mm.

[0085] Preferably, the ratio relationship between the thickness L3 of the blade electrode and the length L1 of the blade electrode is: L3:L1 = 1:10 - 50, more preferably L3:L1 = 1:20 - 30, and further preferably L3:L1 = 1:20 - 25.

[0086] In the present invention, the unit of the thickness L3 and the length L1 of the blade electrode can both be mm.

[0087] Preferably, an active connection mechanism connected to the base is provided at the upper end of the blade electrode, so that the blade electrode can freely adjust its position in the area below the base.

[0088] In the present invention, there is no particular limitation on the way the active connection mechanism is connected to the base, and it can be fixedly connected or movably connected. The freely adjustable position means adjusting the position in various directions, not limited to Figure 1 the positions shown in the specific embodiments.

[0089] More preferably, an active connection mechanism connected to the base is provided at the upper end of the blade electrode, so that the blade electrode can adjust its position in the vertical and horizontal directions.

[0090] Preferably, the active connection mechanism is vertically connected to the base.

[0091] In the present invention, the active connection mechanism can also be non-vertically connected to the base.

[0092] Preferably, the upper end of the blade electrode and the active connection mechanism are rotatably connected, so that the blade electrode can freely rotate to adjust the angle.

[0093] More preferably, the upper end of the blade electrode and the active connection mechanism are rotatably connected, so that the blade electrode can rotate to adjust the included angle with the vertical direction.

[0094] Preferably, the included angle θ between the extended hypotenuse lines of every two blade electrodes at symmetric positions is 10° - 90°, more preferably 30° - 60°.

[0095] In the present invention, "every two blade electrodes at symmetric positions" means that the present invention does not limit that there are only two blade electrodes at symmetric positions, but only makes specific limitations on two blade electrodes at symmetric positions.

[0096] Preferably, the proportional relationship between the minimum distance D2 between every two blade electrodes at symmetric positions and the diameter D1 of the inner cylinder is: D2:D1 = 1:20 - 100, more preferably D2:D1 = 1:30 - 70, and further preferably D2:D1 = 1:35 - 50.

[0097] In the present invention, the minimum distance D2 refers to the distance between the two closest points of two blade electrodes at symmetric positions, and the position of the minimum distance D2 of blade electrodes with different shapes will be different.

[0098] In the present invention, the unit of the minimum distance D2 between every two of the blade electrodes at the symmetric positions and the diameter D1 of the inner cylinder can both be mm.

[0099] Preferably, the proportional relationship between the diameter D4 of the gas nozzle and the diameter D1 of the inner cylinder is: D4:D1 = 1:35 - 100, more preferably D4:D1 = 1:40 - 70, and still more preferably D4:D1 = 1:45 - 65.

[0100] In the present invention, the diameter D4 of the gas nozzle refers to the inner diameter of the gas nozzle.

[0101] In the present invention, the unit of the diameter D4 of the gas nozzle and the diameter D1 of the inner cylinder can both be mm.

[0102] Preferably, the proportional relationship between the distance L4 from the arc starting end of the blade electrode to the outlet of the gas nozzle and the length L2 of the inner cylinder is: L4:L2 = 1:5 - 30, more preferably L4:L2 = 1:7 - 20, and still more preferably L4:L2 = 1:10 - 15.

[0103] In the present invention, the arc starting end of the blade electrode refers to the positions of both ends of the above-mentioned minimum distance D2 on the blade electrode, and the distance L4 from the arc starting end of the blade electrode to the outlet of the gas nozzle refers to the vertical distance between the outlet of the gas nozzle and the midpoint of the minimum distance D2 of the two blade electrodes.

[0104] In the present invention, the unit of the distance L4 from the arc starting end of the blade electrode to the outlet of the gas nozzle and the length L2 of the inner cylinder can both be mm.

[0105] The sliding arc plasma reactor provided by the present invention can make the raw material gas pass through the discharge area formed by the blade electrodes more concentratedly, thereby effectively increasing the gas flow rate passing through this discharge area and improving the conversion efficiency of the reactants.

[0106] Preferably, the material forming the inner cylinder is an insulating material or a conductive material provided with an insulating lining.

[0107] More preferably, the insulating material is selected from at least one of ordinary glass, quartz glass, and corundum.

[0108] In the present invention, on the premise of avoiding contact between the blade electrode and the inner cylinder, the material forming the inner cylinder can also be a conductive material.

[0109] In the present invention, there is no particular limitation on the shape of the inner cylinder, as long as it can provide a sealed space for the reactor, and it can be cylindrical, rectangular or other various shapes that can achieve the foregoing invention object of the present invention.

[0110] Preferably, the material forming the lower reaction zone is a metallic material.

[0111] Preferably, the lower reaction zone is in a conical shape. The inventors have found that this shape is more conducive to the distribution of reaction gases.

[0112] Preferably, the lower reaction zone is a reaction zone where a catalyst bed can be provided, and the proportional relationship between the height L5 of the catalyst bed and the length L2 of the inner cylinder is: L5:L2 = 1:2 - 15, more preferably L5:L2 = 1:3 - 12, and further preferably L5:L2 = 1:5 - 10. The height L5 of the catalyst bed is the height of the cone of the lower reaction zone.

[0113] In the present invention, the height L5 of the catalyst bed is the height of the bed layer in the lower reaction zone where the catalyst can be added. The units of both the height L5 of the catalyst bed and the length L2 of the inner cylinder can be mm.

[0114] In the sliding arc plasma reactor provided by the present invention, a catalyst capable of catalyzing methane conversion can be filled, and the catalyst is preferably filled in the lower reaction zone of the reactor. The present invention has no particular requirements on the filling volume and filling type of the catalyst, and various catalysts known in the art for catalyzing methane conversion can be used.

[0115] Preferably, the heat transfer medium inlet and the heat transfer medium outlet are respectively arranged at the lower part and the upper part of the outer cylinder.

[0116] Preferably, the side-line feed inlet is arranged in the middle of the inner cylinder.

[0117] As described above, the fourth aspect of the present invention provides a method for plasma conversion of methane, which is implemented in the sliding arc plasma reactor described in the third aspect above. The method includes:

[0118] Under plasma discharge conditions, a raw material gas containing methane is introduced into the inner cylinder of the sliding arc plasma reactor through the reactor inlet and the gas nozzle, and a reaction gas containing hydrogen is introduced into the inner cylinder of the sliding arc plasma reactor through the side feed inlet, so that the raw material gas sequentially passes through the discharge region formed by the blade electrodes and the lower reaction zone to carry out methane conversion reaction. The product obtained after the reaction is led out of the sliding arc plasma reactor through the product outlet; and the temperature required for the sliding arc plasma reactor is maintained by continuously introducing a heat transfer medium into the outer cylinder of the sliding arc plasma reactor through the heat transfer medium inlet and leading out the heat transfer medium through the heat transfer medium outlet.

[0119] The method for plasma conversion of methane provided by the present invention has no particular limitation on the reaction conditions involved in the conversion of methane to produce ethylene, and can be carried out under various conditions involved in the conventional plasma conversion of methane methods in the art. The examples of the present invention exemplarily list the conditions for converting methane to produce ethylene, and those skilled in the art should not understand it as a limitation of the present invention.

[0120] The method for plasma conversion of methane provided by the present invention has no particular limitation on the concentration of methane in the reaction gas at the reactor inlet. For example, the concentration of methane in the gas can be 0.01 - 100% by volume. Exemplarily, it can be 5% by volume, 10% by volume, 15% by volume, 20% by volume, 25% by volume, 30% by volume, 35% by volume, 40% by volume, 45% by volume, 50% by volume, 55% by volume, 60% by volume, 65% by volume, 70% by volume, 75% by volume, 80% by volume, 85% by volume, 90% by volume, 95% by volume.

[0121] In the present invention, after the reaction gas passes through the discharge region formed by the blade electrodes, it carries the heat and reactants generated by the discharge into the lower reaction zone, and the heat can provide the heat required for the catalyst bed in the lower reaction zone, without the need for additional heating of the catalyst bed, and can reduce energy consumption without affecting the conversion efficiency.

[0122] In the present invention, the heat transfer medium can be a raw material gas, boiling water, heat transfer oil, cooling water, etc. Using the raw material gas for heat exchange can not only reduce the reactor temperature but also effectively utilize the heat generated by the plasma, further reducing the plasma energy consumption; using boiling water for heat exchange can maintain a constant temperature of the reactor to by-product steam with heat, improving the economy of the plasma process; heat transfer oil and cooling water are mainly used for cooling, and the recovery and utilization of heat are relatively less. Due to their wide applicability, they can be considered as cooling media.

[0123] In the present invention, the plasma process generates significant heat. After long-term operation, the heat inside the plasma cannot be dissipated. The materials of the blade electrode and the reactor wall have high temperature requirements. By jointly cooling the reactor wall and the electrode, the temperature of the reactor wall and the blade electrode can be effectively reduced, the erosion rate of the electrode coating can be slowed down, and the working time of the plasma reactor can be increased.

[0124] The method for converting methane by plasma provided by the present invention can achieve continuous and stable operation of the reaction at a high reactant conversion efficiency, can reduce energy consumption, effectively inhibit carbon deposition, and compared with the traditional methane-to-olefin process, there is no CO2 generation, the ethylene yield is high, and there is no risk of combustion and explosion, which is safer and more environmentally friendly.

[0125] The following combines Figure 1 Provide a preferred specific implementation structure of the sliding arc plasma reactor of the present invention. Specifically:

[0126] The reactor has a coaxial jacketed structure, and the reactor includes:

[0127] An inner cylinder, on which a reactor inlet 1, a side-line feed inlet 4, a lower reaction zone, and a product outlet 7 are respectively arranged;

[0128] An outer cylinder, which is nested outside the inner cylinder, and a heat transfer medium inlet 5 and a heat transfer medium outlet 6 are respectively arranged on the outer cylinder;

[0129] A blade electrode sliding arc generator, which includes a gas nozzle 2, a blade electrode 3, and a base 8. The blade electrode is the blade electrode described in the second aspect above;

[0130] Among them, the side-line feed inlet 4 passes through the outer cylinder and leads into the inner cylinder, so that the reaction gas can enter the inner cylinder through the side-line feed inlet 4; two symmetrically distributed blade electrodes 3 are arranged on the base 8 of the blade electrode sliding arc generator, so that a discharge area can be formed between the blade electrodes 3; the gas nozzle 2 is arranged at the center of the base 8, and the gas nozzle 2 is communicated with the intake pipeline of the reactor inlet 1, so that the raw material gas can enter the inner cylinder from the reactor inlet 1 through the gas nozzle 2.

[0131] Preferably, an active connection mechanism 9 is arranged at the upper end of the blade electrode 3 and is connected to the base 8, so that the position of the blade electrode 3 can be adjusted in the vertical and horizontal directions.

[0132] Preferably, the active connection mechanism 9 is vertically connected to the base 8.

[0133] Preferably, the upper end of the blade electrode 3 is rotatably connected to the movable connection mechanism 9, so that the blade electrode 3 can rotate to adjust the angle with the vertical direction.

[0134] The following provides a preferred specific implementation manner for converting methane using the sliding arc plasma reactor described above in the present invention:

[0135] Nitrogen is introduced into the inner cylinder of the sliding arc plasma reactor from the reactor inlet to remove the air in the discharge area and the gas is led out from the product outlet. Then, a raw material gas containing methane is introduced into the inner cylinder of the sliding arc plasma reactor from the reactor inlet, and a reaction gas containing hydrogen is introduced into the inner cylinder through the side feed inlet. After the airflow of the raw material gas is stable, the high-voltage power supply is turned on, and a plasma discharge field is formed between the blade electrodes by adjusting the voltage and frequency. The raw material gas sequentially passes through the discharge area formed by the blade electrodes and the lower reaction area, and ionization and hydrogenation reactions occur respectively. The product obtained after the reaction is led out of the sliding arc plasma reactor from the product outlet; and the temperature required for the sliding arc plasma reactor is maintained by continuously introducing a heat transfer medium into the outer cylinder from the heat transfer medium inlet provided at the lower part of the outer cylinder of the sliding arc plasma reactor and leading out the heat transfer medium from the heat transfer medium outlet provided at the upper part of the outer cylinder.

[0136] The present invention will be described in detail below with examples.

[0137] In the following examples, unless otherwise specified, the raw materials involved are commercially available products.

[0138] In the following examples, the methane conversion rate, ethylene selectivity, ethane selectivity, acetylene selectivity, selectivity of hydrocarbons above C3, carbon deposition, and ethylene specific consumption are calculated according to the following formulas respectively:

[0139] Methane conversion rate % = (molar amount of methane at inlet - molar amount of methane at outlet) / molar amount of methane at inlet × 100%;

[0140] Ethylene selectivity % = (molar amount of ethylene at outlet) × 2 / (molar amount of methane at inlet - molar amount of methane at outlet) × 100%;

[0141] Ethane selectivity % = (molar amount of ethane at outlet) × 2 / (molar amount of methane at inlet - molar amount of methane at outlet) × 100%;

[0142] Acetylene selectivity % = (molar amount of acetylene at outlet) × 2 / (molar amount of methane at inlet - molar amount of methane at outlet) × 100%;

[0143] Selectivity of hydrocarbons above C3 % = Σ(C n% of carbon deposition = 1 - [Σ (moles of carbon in the outlet) × n / (moles of methane in the inlet - moles of methane in the outlet)] × 100%, where n is an integer from 3 to 5;

[0144] % of carbon deposition = 1 - [Σ (C n outlet molar amount) × n / (inlet methane molar amount - outlet methane molar amount)] × 100%, where n is an integer from 2 to 5;

[0145] Specific ethylene consumption (kJ / L) = 60 × power (W) / ethylene flow rate (mL / min).

[0146] Example 1

[0147] The methane conversion reaction was carried out using a sliding arc plasma reactor. The specific structure and structural parameters of the reactor are as follows:

[0148] The reactor has a coaxial jacketed structure and includes:

[0149] Inner cylinder, on which a reactor inlet, a side-line feed inlet, a lower reaction zone and a product outlet are respectively arranged;

[0150] Outer cylinder, which is nested outside the inner cylinder, and a heat transfer medium inlet and a heat transfer medium outlet are respectively arranged on the outer cylinder;

[0151] Blade electrode sliding arc generator, which includes a gas nozzle, a blade electrode and a base. The blade electrode is coated with HfO2 and ZnO thin films on the coating I and the coating II respectively by atomic layer deposition. The number of single-layer atomic layer deposition metal oxide thin films in each coating is 200, and the coating position is the blade surface. When coating, the part of the blade electrode except the blade surface is completely covered. The area of the coating I accounts for 1 / 3 of the total area of the blade surface. The total area of the blade surface in this example and all the following examples is the same, which is 27 mm 2 ;

[0152] Among them, the side-line feed inlet passes through the outer cylinder and leads into the inner cylinder, so that the reaction gas can enter the inner cylinder through the side-line feed inlet; 2 symmetrically distributed blade electrodes are arranged on the base of the blade electrode sliding arc generator, so that a discharge area can be formed between the blade electrodes; the gas nozzle is arranged at the center of the base, and the gas nozzle is communicated with the intake pipeline of the reactor inlet, so that the raw material gas can enter the inner cylinder from the reactor inlet through the gas nozzle.

[0153] An active connection mechanism connected to the base is provided at the upper end of the blade electrode, enabling the blade electrode to adjust its position in the vertical and horizontal directions; the active connection mechanism is vertically connected to the base; the upper end of the blade electrode is rotatably connected to the active connection mechanism, enabling the blade electrode to rotate to adjust the angle with the vertical direction;

[0154] The material forming the blade electrode is 316L stainless steel;

[0155] The proportional relationship between the length L1 of the blade electrode and the diameter D1 of the inner cylinder is: L1:D1 = 1:1;

[0156] The proportional relationship between the length L1 of the blade electrode and the length L2 of the inner cylinder is: L1:L2 = 1:3;

[0157] The proportional relationship between the thickness L3 of the blade electrode and the length L1 of the blade electrode is: L3:L1 = 1:20;

[0158] The proportional relationship between the minimum distance D2 between two blade electrodes at symmetric positions and the diameter D1 of the inner cylinder is: D2:D1 = 1:35;

[0159] The proportional relationship between the diameter D4 of the gas nozzle and the diameter D1 of the inner cylinder is: D4:D1 = 1:46;

[0160] The proportional relationship between the distance L4 from the arc-starting end of the blade electrode to the outlet of the gas nozzle and the length L2 of the inner cylinder is: L4:L2 = 1:10;

[0161] The proportional relationship between the distance L4 from the arc-starting end of the blade electrode to the outlet of the gas nozzle and the minimum distance D2 between two blade electrodes at symmetric positions is: L4:D2 = 1:0.2;

[0162] The included angle θ inside the extended hypotenuse of two blade electrodes at symmetric positions is 45°;

[0163] The material forming the inner cylinder is quartz glass;

[0164] The proportional relationship between the height L5 of the catalyst bed and the length L2 of the inner cylinder is: L5:L2 = 1:7;

[0165] In this embodiment, the volume of the sliding arc plasma reactor is 3L.

[0166] The operating conditions of the sliding arc plasma reactor in this embodiment are as follows:

[0167] First, cool water is introduced into the outer cylinder through the heat-conducting medium inlet, and then nitrogen is introduced into the inner cylinder through the reactor inlet for 30 minutes at an inlet gas flow rate of 3 L / min to displace the oxygen in the reactor. Then, a mixed gas is introduced with a methane inlet flow rate of 1 L / min and a hydrogen inlet flow rate of 3 L / min. The power supply is turned on, the voltage and frequency are adjusted, the voltage is adjusted to 5 kV, the frequency is adjusted to 25 kHz, and the discharge starts. Then the voltage is adjusted to the specified 2 kV, and the power is 300 W at this time, and the reaction proceeds for 8 hours.

[0168] The tail gas and energy consumption are analyzed, and the results are shown in Table 1. The analysis results of the tail gas and energy consumption of the remaining examples are also listed in Table 1.

[0169] Example 2

[0170] In this example, a sliding arc plasma reactor similar to that in Example 1 is used for the methane conversion reaction. The difference is that in this example:

[0171] The blade electrode uses atomic layer deposition to coat HfO2 and SnO2 thin films on the coating I and the coating II respectively, and the area of the coating I accounts for 1 / 2 of the total area of the blade surface.

[0172] The rest are the same as those in Example 1.

[0173] Example 3

[0174] In this example, a sliding arc plasma reactor similar to that in Example 1 is used for the methane conversion reaction. The difference is that in this example:

[0175] The blade electrode uses atomic layer deposition to coat HfO2 and Al2O3 thin films on the coating I and the coating II respectively.

[0176] The rest are the same as those in Example 1.

[0177] Example 4

[0178] In this example, a sliding arc plasma reactor similar to that in Example 1 is used for the methane conversion reaction. The difference is that in this example:

[0179] The blade electrode uses atomic layer deposition to coat ZrO2 and ZnO thin films on the coating I and the coating II respectively.

[0180] The rest are the same as those in Example 1.

[0181] Example 5

[0182] In this example, a sliding arc plasma reactor similar to that in Example 1 is used for the methane conversion reaction. The difference is that in this example: [[ID=4,6]]

[0183] The blade electrode coats ZrO2 and SnO2 films on the coating I and the coating II respectively by atomic layer deposition;

[0184] The rest are the same as those in Example 1.

[0185] Example 6

[0186] In this example, a sliding arc plasma reactor similar to that in Example 1 is used for methane conversion reaction. The difference is that in this example:

[0187] The blade electrode coats ZrO2 and Al2O3 films on the coating I and the coating II respectively by atomic layer deposition;

[0188] The rest are the same as those in Example 1.

[0189] Example 7

[0190] In this example, a sliding arc plasma reactor similar to that in Example 1 is used for methane conversion reaction. The difference is that in this example:

[0191] The blade electrode coats HfO2 and Y2O3 films on the coating I and the coating II respectively by atomic layer deposition;

[0192] The rest are the same as those in Example 1.

[0193] Example 8

[0194] In this example, a sliding arc plasma reactor similar to that in Example 1 is used for methane conversion reaction. The difference is that in this example:

[0195] The blade electrode coats La2O3 and ZnO films on the coating I and the coating II respectively by atomic layer deposition;

[0196] The rest are the same as those in Example 1.

[0197] Example 9

[0198] In this example, a sliding arc plasma reactor similar to that in Example 1 is used for methane conversion reaction. The difference is that in this example:

[0199] The blade electrode coats Ta2O5 and ZnO films on the coating I and the coating II respectively by atomic layer deposition;

[0200] The rest are the same as those in Example 1.

[0201] Comparative Example 1

[0202] This comparative example uses a sliding arc plasma reactor similar to that in Example 1 to carry out the methane conversion reaction. The difference is that in this comparative example:

[0203] The blade electrode is not coated;

[0204] The rest are the same as those in Example 1.

[0205] Comparative Example 2

[0206] This comparative example uses a sliding arc plasma reactor similar to that in Example 1 to carry out the methane conversion reaction. The difference is that in this comparative example:

[0207] The blade electrode is coated using an existing chemical electroplating technique, and the coating material is copper. The specific conditions are as follows: the concentration of copper nitrate is 0.1 mol / mL, the voltage is 0.3 V, pH = 6.7, the temperature is 25 °C, and the electroplating time is 300 s. When coating, all parts of the blade electrode except the surface of the blade edge are covered;

[0208] The rest are the same as those in Example 1.

[0209] Comparative Example 3

[0210] This comparative example uses a sliding arc plasma reactor similar to that in Example 1 to carry out the methane conversion reaction. The difference is that in this comparative example:

[0211] The blade electrode is coated with 200 HfO2 thin films by atomic layer deposition;

[0212] The rest are the same as those in Example 1.

[0213] Comparative Example 4

[0214] This comparative example uses a sliding arc plasma reactor similar to that in Example 1 to carry out the methane conversion reaction. The difference is that in this comparative example:

[0215] The blade electrode is coated with 200 ZnO thin films by atomic layer deposition;

[0216] The rest are the same as those in Example 1.

[0217] Comparative Example 5

[0218] This comparative example uses a sliding arc plasma reactor similar to that in Example 1 to carry out the methane conversion reaction. The difference is that in this comparative example:

[0219] The blade electrode is coated with TiO2 and ZnO thin films on the coating layer I and the coating layer II respectively by atomic layer deposition, and the difference in their dielectric constants is greater than 70 C 2 / (N·M 2 );

[0220] The rest are the same as those in Example 1.

[0221] Table 1

[0222]

[0223] It can be seen from the above results that the solution provided by the present invention modifies the blade electrode by coating a dielectric layer on the surface of the blade electrode, thereby weakening the arc energy, reducing the plasma field temperature, effectively simplifying the process flow of methane conversion to olefins, directly and efficiently converting methane to ethylene under the action of an electric field, improving the discharge efficiency, and preventing electrode ablation; and the solution provided by the present invention can continuously and stably carry out the reaction at a relatively high reactant conversion efficiency, reduce energy consumption, effectively inhibit carbon deposition, and compared with the traditional methane-to-olefins process, there is no CO2 generation, the ethylene yield is high, and there is no risk of combustion and explosion, which is safer and more environmentally friendly.

[0224] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for coating a blade electrode, characterized in that, The method includes: applying a coating material to the blade electrode in the sliding arc plasma reactor by atomic layer deposition to obtain a coating on the surface of the blade electrode, the coating containing at least two monolayer atomic layer deposition metal oxide films arranged in layers, and the coating being a semiconductor material. Among them, in the blade electrode, the applied coating material makes the types of semiconductor materials of coating I and coating II different. Coating I is the middle area of the blade surface, and coating II is the areas on both sides of the blade surface; Among them, the applied coating material makes the dielectric constant of the semiconductor material of the coating I 6-70 C higher than that of the semiconductor material of the coating II 2 / (N·M 2 ).

2. The method according to claim 1, wherein The applied coating material makes the dielectric constant of the semiconductor material of the coating I 10 - 25 C higher than that of the semiconductor material of the coating II 2 / (N·M 2 ).

3. The method according to claim 1 or 2, wherein The coating material is an organic compound containing a metal element.

4. The method according to claim 1 or 2, wherein The semiconductor material is a metal oxide.

5. The method according to claim 1 or 2, wherein Coating I is selected from at least one of ZrO2, HfO2, TiO2, La2O3, Ta2O5, and coating II is selected from at least one of Al2O3, SnO2, ZnO, Y2O3.

6. According to the method described in claim 1 or 2, wherein, The step of applying a coating to the blade electrode in the sliding arc plasma reactor by atomic layer deposition includes: in the atomic layer deposition device, (1) In the presence of a carrier gas, open the ALD valve of the metal source tank, and the coating material in the metal source tank enters the reaction chamber containing oxygen, so that the coating material reacts with oxygen on the surface of the blade electrode in the reaction chamber to form a monolayer atomic layer deposition metal oxide film; (2) Repeat step (1) to obtain the coating. Each repetition forms a monolayer atomic layer deposition metal oxide film, and the coating thickness is adjusted by controlling the number of repetitions; (3) Use two kinds of the coating materials to perform repeated operations through the above steps (1) to (2) in the areas of coating I and coating II respectively to form two coatings.

7. The method according to claim 6, wherein, In step (1), the temperature of the metal source tank is 140 - 160 °C, the temperature of the reaction chamber is 50 - 400 °C, and the temperature of the transport pipeline and the ALD valve is 180 - 200 °C.

8. The method according to claim 7, wherein, In step (1), evacuate the reaction chamber and the transport pipeline to a pressure of 10 - 200 Pa.

9. The method according to claim 6, wherein, In step (1), the flow rate of the carrier gas is 10 - 200 sccm.

10. The method according to claim 6, wherein In step (1), the opening time of the ALD valve is 50 - 2000 ms.

11. The method according to claim 6, wherein, In step (1), an inert gas pulse is also introduced to clean the reaction chamber.

12. The method according to claim 11, wherein, The cleaning time is 1 - 200 s.

13. A blade electrode obtained by coating according to the method described in any one of claims 1 - 12.

14. A sliding arc plasma reactor, characterized in that, The reactor has a coaxial jacketed structure, and the reactor includes: An inner cylinder, on which a reactor inlet (1), a side-line feed inlet (4), a lower reaction zone, and a product outlet (7) are respectively arranged; An outer cylinder, which is nested outside the inner cylinder, and on which a heat transfer medium inlet (5) and a heat transfer medium outlet (6) are respectively arranged; A blade electrode sliding arc generator, which includes a gas nozzle (2), a blade electrode (3), and a base (8); Among them, the side-line feed inlet (4) passes through the outer cylinder and leads into the inner cylinder, enabling the reaction gas to enter the inner cylinder through the side-line feed inlet (4); at least two of the blade electrodes (3) are symmetrically distributed on the base (8) of the blade electrode sliding arc generator, enabling a discharge region to be formed between the blade electrodes (3); the gas nozzle (2) is arranged on the base (8), enabling the raw material gas to enter the inner cylinder from the reactor inlet (1) through the gas nozzle (2). Among them, the blade electrode is the blade electrode described in claim 13.

15. The sliding arc plasma reactor according to claim 14, wherein, Two of the blade electrodes (3) or six of the blade electrodes (3) are symmetrically distributed on the base (8).

16. The sliding arc plasma reactor according to claim 14 or 15, wherein The material forming the blade electrode (3) is a conductive material.

17. The sliding arc plasma reactor according to claim 16, wherein, The conductive material is selected from at least one of 316L stainless steel, tungsten cerium alloy, copper, and copper tungsten alloy.

18. The sliding arc plasma reactor according to claim 14 or 15, wherein The gas nozzle (2) is arranged at the center of the base (8) of the blade electrode sliding arc generator, and the gas nozzle (2) is communicated with the intake pipeline of the reactor inlet (1).

19. The sliding arc plasma reactor according to claim 14 or 15, wherein, The proportional relationship between the length L1 of the blade electrode (3) and the diameter D1 of the inner cylinder is: L1:D1 = 1:1 - 3.

20. The sliding arc plasma reactor according to claim 19, wherein, The proportional relationship between the length L1 of the blade electrode (3) and the diameter D1 of the inner cylinder is: L1:D1 = 1:1 - 2.

21. The sliding arc plasma reactor according to claim 20, wherein, The proportional relationship between the length L1 of the blade electrode (3) and the diameter D1 of the inner cylinder is: L1:D1 = 1:1 - 1.

5.

22. The sliding arc plasma reactor according to claim 14 or 15, wherein, The proportional relationship between the length L1 of the blade electrode (3) and the length L2 of the inner cylinder is: L1:L2 = 1:1.5 - 6.

23. The sliding arc plasma reactor according to claim 22, wherein, The proportional relationship between the length L1 of the blade electrode (3) and the length L2 of the inner cylinder is: L1:L2 = 1:2 - 5.

24. The sliding arc plasma reactor according to claim 23, wherein, The proportional relationship between the length L1 of the blade electrode (3) and the length L2 of the inner cylinder is: L1:L2 = 1:2 - 3.

25. The sliding arc plasma reactor according to claim 14 or 15, wherein, The proportional relationship between the thickness L3 of the blade electrode (3) and the length L1 of the blade electrode (3) is: L3:L1 = 1:10 - 50.

26. The sliding arc plasma reactor according to claim 25, wherein, The proportional relationship between the thickness L3 of the blade electrode (3) and the length L1 of the blade electrode (3) is: L3:L1 = 1:20 - 30.

27. The sliding arc plasma reactor according to claim 26, wherein, The proportional relationship between the thickness L3 of the blade electrode (3) and the length L1 of the blade electrode (3) is: L3:L1 = 1:20 - 25.

28. The sliding arc plasma reactor according to claim 14 or 15, wherein, The upper end of the blade electrode (3) is provided with a movable connection mechanism (9) connected to the base (8), enabling the blade electrode (3) to freely adjust its position in the lower region of the base (8).

29. The sliding arc plasma reactor according to claim 28, wherein, The upper end of the blade electrode (3) is provided with a movable connection mechanism (9) connected to the base (8), enabling the blade electrode (3) to adjust its position in the vertical and horizontal directions.

30. The sliding arc plasma reactor according to claim 29, wherein, The movable connection mechanism (9) is vertically connected to the base (8).

31. The sliding arc plasma reactor according to claim 28, wherein, The upper end of the blade electrode (3) is rotatably connected to the movable connection mechanism (9), so that the blade electrode (3) can rotate freely to adjust the angle.

32. The sliding arc plasma reactor according to claim 31, wherein, The upper end of the blade electrode (3) is rotatably connected to the movable connection mechanism (9), so that the blade electrode (3) can rotate to adjust the included angle with the vertical direction.

33. The sliding arc plasma reactor according to claim 14 or 15, wherein, The included angle θ between the extended lines of the hypotenuses of every two blade electrodes (3) at symmetric positions is 10° - 90°.

34. The sliding arc plasma reactor according to claim 33, wherein, The included angle θ between the extended lines of the hypotenuses of every two blade electrodes (3) at symmetric positions is 30° - 60°.

35. The sliding arc plasma reactor according to claim 14 or 15, wherein The proportional relationship between the minimum distance D2 between every two blade electrodes (3) at symmetric positions and the diameter D1 of the inner cylinder is: D2:D1 = 1:20 - 100.

36. The sliding arc plasma reactor according to claim 35, wherein The proportional relationship between the minimum distance D2 between every two blade electrodes (3) at symmetric positions and the diameter D1 of the inner cylinder is: D2:D1 = 1:30 - 70.

37. The sliding arc plasma reactor according to claim 36, wherein, The proportional relationship between the minimum distance D2 between every two blade electrodes (3) at symmetric positions and the diameter D1 of the inner cylinder is: D2:D1 = 1:35 - 50.

38. The sliding arc plasma reactor according to claim 14 or 15, wherein The proportional relationship between the diameter D4 of the gas nozzle (2) and the diameter D1 of the inner cylinder is: D4:D1 = 1:35 - 100.

39. The sliding arc plasma reactor according to claim 38, wherein, The proportional relationship between the diameter D4 of the gas nozzle (2) and the diameter D1 of the inner cylinder is: D4:D1 = 1:40 - 70.

40. The sliding arc plasma reactor according to claim 39, wherein, The proportional relationship between the diameter D4 of the gas nozzle (2) and the diameter D1 of the inner cylinder is: D4:D1 = 1:45 - 65.

41. The sliding arc plasma reactor according to claim 14 or 15, wherein, The proportional relationship between the distance L4 between the arc-starting end of the blade electrode (3) and the outlet of the gas nozzle (2) and the length L2 of the inner cylinder is: L4:L2 = 1:5 - 30.

42. The sliding arc plasma reactor according to claim 41, wherein, The proportional relationship between the distance L4 between the arc-starting end of the blade electrode (3) and the outlet of the gas nozzle (2) and the length L2 of the inner cylinder is: L4:L2 = 1:7 - 20.

43. The sliding arc plasma reactor according to claim 42, wherein, The proportional relationship between the distance L4 between the arc-starting end of the blade electrode (3) and the outlet of the gas nozzle (2) and the length L2 of the inner cylinder is: L4:L2 = 1:10 - 15.

44. The sliding arc plasma reactor according to claim 14 or 15, wherein, The material forming the inner cylinder is an insulating material or a conductive material provided with an insulating lining.

45. The sliding arc plasma reactor according to claim 44, wherein, The insulating material is selected from at least one of ordinary glass, quartz glass, and corundum.

46. The sliding arc plasma reactor according to claim 14 or 15, wherein The material forming the lower reaction zone is a metallic material.

47. The sliding arc plasma reactor according to claim 46, wherein The lower reaction zone is conical.

48. The sliding arc plasma reactor according to claim 14 or 15, wherein, The lower reaction zone is a reaction zone capable of being provided with a catalyst bed. The proportional relationship between the height L5 of the catalyst bed and the length L2 of the inner cylinder is: L(5):L(2) = 1:2 - 15. The height L5 of the catalyst bed is the height of the cone of the lower reaction zone.

49. The sliding arc plasma reactor according to claim 48, wherein, The lower reaction zone is a reaction zone capable of being provided with a catalyst bed. The proportional relationship between the height L5 of the catalyst bed and the length L2 of the inner cylinder is: L(5):L(2) = 1:3 - 12.

50. The sliding arc plasma reactor according to claim 49, wherein, The lower reaction zone is a reaction zone where a catalyst bed can be arranged, and the proportional relationship between the height L5 of the catalyst bed and the length L2 of the inner cylinder is: L5:L2 = 1:5 - 10.

51. The sliding arc plasma reactor according to claim 14 or 15, wherein, The heat transfer medium inlet (5) and the heat transfer medium outlet (6) are respectively arranged at the lower part and the upper part of the outer cylinder.

52. The sliding arc plasma reactor according to claim 14 or 15, wherein, The side-line feed inlet (4) is arranged in the middle of the inner cylinder.

53. A method for the conversion of methane by plasma, characterized in that, This method is implemented in the sliding arc plasma reactor described in any one of claims 14 - 52, and this method includes: Under plasma discharge conditions, introducing a raw material gas containing methane into the inner cylinder of the sliding arc plasma reactor through the reactor inlet (1) and the gas nozzle (2), and introducing a reaction gas containing hydrogen into the inner cylinder of the sliding arc plasma reactor through the side-line feed inlet (4), so that the raw material gas sequentially passes through the discharge region formed by the blade electrode (3) and the lower reaction zone to carry out a methane conversion reaction, and the product obtained after the reaction is led out of the sliding arc plasma reactor through the product outlet (7); and, maintaining the temperature required for the sliding arc plasma reactor by continuously introducing a heat transfer medium into the outer cylinder of the sliding arc plasma reactor through the heat transfer medium inlet (5) and leading out the heat transfer medium through the heat transfer medium outlet (6).

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