A green electricity microwave discharge plasma methane pyrolysis system and method for co-producing hydrogen and carbon

Abstract

The present invention discloses a green electricity microwave discharge plasma methane pyrolysis hydrogen and carbon co-production system and method, belonging to the technical field of methane thermal pyrolysis for hydrogen production. The system includes a green electricity power supply system, a gas supply system, a microwave discharge plasma pyrolysis system, a carbon product separation and collection system, a gas circulation system, and a gas separation and purification system. The present invention can achieve a methane conversion rate of >95% under low flow rate and low energy consumption, realizing the efficient pyrolysis of methane; the directional and controllable generation of products can be achieved by adjusting the microwave power and the gas composition in the gas supply system, and the directional selective regulation of gaseous products such as ethane and pure hydrogen can be achieved by changing the gas circulation.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by methane pyrolysis, and particularly relates to a green electricity microwave discharge plasma methane pyrolysis hydrogen-carbon co-production system and method. Background Art

[0002] Microwave discharge plasma is one of the common plasma pyrolysis technologies, which has the characteristics of high ionization and decomposition degree, high electron temperature and density, and high energy efficiency. It can be designed without electrodes, has the ability to increase the reaction rate and lower the reaction activation energy, and can achieve efficient methane pyrolysis to obtain low-carbon hydrogen and high-value by-products.

[0003] Currently, the main way of microwave discharge plasma action is the plasma torch. This method realizes the ignition of the plasma torch through high energy consumption and high gas velocity, and can realize the action of high-energy electrons on the reactants to achieve the purpose of reactant conversion. This method requires a huge amount of energy to start and also requires a high energy input to maintain the plasma state. There are problems such as high energy consumption, high gas velocity, and uncontrollable reaction.

[0004] Adding a catalyst can reduce the reaction activity in exchange for the methane conversion rate at low power and low flow rate. However, the deactivation of the catalyst will lead to low reaction stability, and at the same time, the gaseous products are miscellaneous and impure, resulting in an increase in the later separation cost. CN111085242B discloses a method and catalyst for microwave catalytic methane hydrogen production. Using the Ni / Mo2C / SBA-15 catalyst to catalytically convert methane directly to hydrogen under microwave conditions, by adjusting different catalyst parameters and reaction conditions, a certain degree of increase in heating temperature and improvement of conversion rate are achieved, but the power consumption is still very high. CN116553525A discloses an application and application method of a non-thermal anaerobic plasma methane pyrolysis system. This application method needs to be carried out at a high power of 15 - 30KW and a high flow rate of 100 - 300L / min. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a green electricity microwave discharge plasma methane pyrolysis hydrogen-carbon co-production system and method. Compared with the traditional microwave discharge plasma methane pyrolysis method, this method achieves a high methane conversion rate (>95%) at a low gas velocity (<0.02m / s, 30% of the traditional method) and low energy consumption (<400kJ / mol, 40% of the traditional method) without adding any catalyst. At the same time, it realizes the orderly and controllable conversion of gaseous products and the production of high-value carbon. This method can realize the industrial production of green hydrogen and high-value carbon from methane, with low-cost investment and low operating expenses, without the need for a catalyst and water, low implementation difficulty, and low energy consumption.

[0006] To achieve the above technical objectives, the technical solution implemented by the present invention is as follows:

[0007] In the first aspect of the present invention, a green electricity microwave discharge plasma methane cracking hydrogen-carbon co-production system is provided, including:

[0008] A green electricity supply system for accessing green electricity;

[0009] A gas supply system for providing stable hydrocarbon compounds and discharge medium gases;

[0010] A microwave discharge plasma cracking system for cracking hydrocarbon compounds to produce gases and carbon products;

[0011] A carbon product separation and collection system for separating and collecting carbon products from gases;

[0012] A gas circulation system for circulating part of the cracked gas;

[0013] A gas separation and purification system for separating and purifying hydrogen.

[0014] Preferably, the hydrocarbon compound is selected from methane, ethane, ethylene or acetylene.

[0015] In the embodiments of the present invention, the microwave discharge plasma cracking system is equipped with fillers and a microwave source. The fillers are made of wave-absorbing materials with a radius of curvature less than or equal to the tip length or radius. Further, the filler materials are selected from metal needles, metal wires, metal meshes or activated carbon.

[0016] Preferably, the discharge medium gas is selected from chemically stable gases such as argon or nitrogen that are easy to form discharge plasmas.

[0017] In the second aspect of the present invention, a green electricity microwave discharge plasma methane cracking hydrogen-carbon co-production method is provided, including the following steps:

[0018] S1. Place the fillers in the reaction area of the microwave discharge plasma cracking system;

[0019] S2. Introduce the discharge medium gas into the microwave reaction chamber of the microwave discharge plasma cracking system to provide a discharge environment for the reaction chamber;

[0020] S3. Adjust the energy input of the microwave generating device, input microwaves into the microwave reaction chamber, and make the fillers in the microwave reaction chamber continuously discharge, forming a stable plasma field around the fillers;

[0021] S4. Adjust the gas input of the gas supply system, introduce a mixture of hydrocarbon compound gas and discharge medium gas into the microwave reaction chamber, and start the microwave discharge plasma cracking reaction;

[0022] S5. The reaction products are separated into gas and solid through the separation and sedimentation area of the microwave discharge plasma cracking system; the carbon products are collected in the carbon product separation and collection system; the gas products are collected after passing through the gas separation and purification system.

[0023] Furthermore, according to the product distribution of the gas separation and purification system, the gas circulation volume and frequency of the gas circulation system are adjusted to control the quality of the gas-solid products.

[0024] Preferably, in step S4, the conditions of the microwave discharge plasma cracking reaction include: the gas velocity is 0.003 m / s to 0.033 m / s; in the mixed gas of hydrocarbon compound gas and discharge medium gas, the content of the hydrocarbon compound gas is any value between 10% and 50%; the energy input of the microwave generating device is adjusted, and the power is any condition between 20 W / mol and 150 W / mol based on the hydrocarbon compound gas.

[0025] The present invention provides a cracking hydrogen production technology in a low-flow mode, which realizes more precise control, more efficient mixing, and lower energy consumption with a lower flow rate. The present invention can control the composition of the products by controlling the reaction time; through the gas circulation system, the products can be pumped back to the reaction area for re-reaction to change the product composition.

[0026] Based on the alkane cracking theory, the high-energy particles in the plasma interact with alkane molecules, resulting in the breaking of chemical bonds and the formation of small molecule products. Alkane cracking involves:

[0027] 1. Microwave energy action: Microwave is a high-frequency electromagnetic wave that can penetrate substances and interact with their molecules. In alkane cracking, the microwave energy is absorbed and converted into heat energy, enabling alkane molecules to obtain sufficient energy for cracking.

[0028] 2. Plasma generation: Microwave energy can trigger gas ionization under specific conditions (such as high-pressure or low-pressure gas environments) to form plasma. Plasma is the fourth state of matter, composed of free electrons, ions, and neutral particles, with high activity and can promote chemical reactions. The high-energy electrons and ions in the plasma can collide with alkane molecules, triggering the cracking reaction.

[0029] 3. Cracking mechanism: The high-energy electrons in the plasma collide with alkane molecules, transferring energy to the alkane molecules, causing their chemical bonds to break, generating free radicals and small molecule products. These free radicals further react to form smaller hydrocarbon molecules, such as olefins and hydrogen.

[0030] 4. Main reaction steps: Excitation and ionization: High-energy electrons collide with alkane molecules, exciting or ionizing them to generate free radicals and ions; Bond breaking: The excited or ionized alkane molecules undergo bond breaking to form small molecule products; Free radical reaction: The generated free radicals further react to form stable products.

[0031] The theory of plasma alkane cracking utilizes the interaction between high-energy particles in the plasma and alkane molecules to initiate chemical bond breaking and generate small molecule products. This technology has advantages such as high efficiency, strong selectivity, and environmental friendliness, and has broad application prospects in multiple fields.

[0032] Compared with the prior art, the beneficial effects of the technical solution of the present invention include:

[0033] 1. The present invention provides a green electricity microwave discharge plasma methane cracking hydrogen-carbon co-production system and method, which can achieve a methane conversion rate of >95% under low flow rate and low energy consumption, realizing the efficient cracking of methane and reducing the energy consumption and cost of the entire reaction process.

[0034] 2. The present invention can achieve the directional and controllable generation of products through the gas circulation system, and can achieve the directional selective regulation of gaseous products such as ethane and pure hydrogen by changing the gas circulation.

[0035] 3. This method can obtain high-value carbon products, such as low-layer graphene products, carbon nanotubes, carbon black, etc. At the same time, no carbon dioxide is generated during this process, which is a cost-effective and environmentally friendly method for cracking methane to produce high-value carbon.

[0036] 4. This method prepares hydrogen by methane cracking, avoiding the large amount of carbon dioxide emissions in the traditional methane steam reforming method, contributing to reducing greenhouse gas emissions and meeting the requirements of environmental protection and sustainable development.

[0037] 5. This system can be started and stopped at any time, and can match unstable electric energies such as solar energy, wind energy, geothermal energy, and tidal energy. It can realize the industrial production of green hydrogen and high-value carbon from methane, with low-cost investment and low operating expenses, without the need for catalysts and water, and has low implementation difficulty. Description of the Drawings

[0038] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0039] Figure 1 It is a schematic structural diagram of a green electricity microwave discharge plasma methane cracking hydrogen-carbon co-production system; wherein, 1 - green electricity power supply system, 2 - gas supply system, 3 - microwave discharge plasma cracking system, 4 - carbon product separation and collection system, 5 - gas circulation system, 6 - gas separation and purification system.

[0040] Figure 2 XRD and Raman spectrum characterization diagrams of carbon products for different embodiments; wherein, (a) is the XRD image of the carbon products of different embodiments, (b) is the Raman image of the carbon products of different embodiments, and (c) and (d) are the Lorentzian fittings of the D peak of the Raman spectrum. Figure 2 Lorentzian fitting of the D peak.

[0041] Figure 3 Schematic structural diagram of the microwave discharge plasma cracking system provided by the present invention; wherein, 301 - reactor, 302 - microwave generating device, 303 - reaction zone, 304 - filler, 305 - separation and sedimentation zone, 306 - carbon product outlet, 307 - inlet, 308 - outlet, 309 - sieve plate. Detailed implementation manners

[0042] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0043] The present invention realizes a method and a system for co-producing hydrogen and carbon by cracking methane using green electricity microwave discharge plasma. The system realizes the controllable cracking of methane at low power consumption and low gas velocity, and simultaneously generates high-value-added carbon products.

[0044] The structure of the system is as Figure 1 shown, and it includes a green electricity power supply system 1, a gas supply system 2, a microwave discharge plasma cracking system 3, a carbon product separation and collection system 4, a gas circulation system 5, and a gas separation and purification system 6. The green electricity power supply system 1 is used for accessing green electricity. The gas supply system 2 is used to provide stable methane and discharge medium gas. The microwave discharge plasma cracking system 3 is equipped with a filler 304 with a certain radius of curvature and a microwave source (microwave generating device 302), and is used for methane cracking to produce gas and carbon. The carbon product separation and collection system 4 is used to separate and collect carbon products from gas. The gas circulation system 5 is used to circulate part of the cracked gas. The gas separation and purification system 6 is used for separating and purifying hydrogen from gas. The green electricity power supply system 1 is electrically connected to the microwave discharge plasma cracking system 3. The gas supply system 2, the carbon product separation and collection system 4, and the gas circulation system 5 are respectively connected to the microwave discharge plasma cracking system 3 through pipelines. The outlet of the gas circulation system 5 is divided into two branches. One branch is connected to the gas separation and purification system 6, and the other branch is connected to the microwave discharge plasma cracking system 3 through the connecting pipeline between the gas supply system 2 and the microwave discharge plasma cracking system 3. The opening and closing of the two branches are controlled by valves. An air pump is provided in the gas circulation system 5 to pump the products back to the reaction zone 303 for re-reaction, thereby changing the product composition.

[0045] As shown Figure 3 in FIG. 1, the microwave discharge plasma cracking system 3 includes a reactor 301 and a microwave generating device 302. The microwave generating device 302 is connected to the green power supply system 1 and powered by the green power supply system 1. The reaction conditions in the reactor 301 are regulated by the microwave generating device 302. An air inlet 307 connected to the gas supply system 2 is provided at the top of the reactor 301, a carbon product outlet 306 is provided at the bottom, and an air outlet 308 connected to the gas circulation system 5 is provided on the side. The inside of the reactor 301 is a microwave reaction chamber. A sieve plate 309 is provided above the air outlet 308, and a filler 304 is placed on the sieve plate 309. The reaction area 303 is above the sieve plate 309, and the separation and sedimentation area 305 is below.

[0046] The gas supply system 2 is connected to the air inlet 307 of the microwave discharge plasma cracking system 3, includes two gas paths, respectively supplying hydrocarbon compounds and discharge medium gas, and switching the two gas paths through a valve.

[0047] Among them, the carbon product separation and collection system 4 is connected to the carbon product outlet 306, and traditional mechanical peeling and other methods can be used to separate and collect carbon products such as graphene, and its structure is not limited.

[0048] The gas circulation system 5 includes a three-way valve and an air pump. The three-way valve is connected to the air outlet 308, the air inlet 307 of the microwave discharge plasma cracking system 3, and the gas separation and purification system 6. By adjusting the opening and closing of the three-way valve and driven by the air pump, the gas product is supplied to the gas separation and purification system 6 or circulated to the microwave discharge plasma cracking system 3.

[0049] The gas separation and purification system 6 is used for the separation and purification of hydrogen. The low-temperature separation method in the prior art can be used to separate hydrogen from the mixed gas by using the boiling points of different components, or an adsorbent can be used to selectively adsorb the gas, or the membrane separation method can be used, etc., which will not be elaborated here.

[0050] Calculate the gas velocity according to the formula Q = V / A.

[0051] Among them, Q is the gas velocity, m / s; V is the flow rate, ml / min. In this embodiment, the cross-sectional radius of the reaction area 303 of the reactor 301 is 9 mm.

[0052] In one or more embodiments of the present invention, under any of the conditions where the flow rate is 50 ml / min, 100 ml / min, 200 ml / min, 300 ml / min, 400 ml / min, 500 ml / min, or any value between 50 ml / min and 500 ml / min, the corresponding gas velocities are 0.00328 m / s, 0.00657 m / s, 0.0131 m / s, 0.0197 m / s, 0.0263 m / s, 0.0328 m / s, or any value between 0.00328 m / s and 0.0328 m / s. Preferably, the gas velocity is 0.003 m / s to 0.033 m / s, more preferably 0.006 m / s to 0.02 m / s, and further preferably 0.006 m / s to 0.01 m / s.

[0053] In one or more embodiments of the present invention, in the microwave discharge plasma cracking reaction conditions, in the mixture of methane and the discharge medium gas, the content of methane is 10%, 30%, 50%, or any value between 10% and 50%; adjusting the energy input of the microwave generating device 302, the power in terms of methane is: 20 W / mol, 30 W / mol, 40 W / mol, 50 W / mol, 60 W / mol, 150 W / mol, or any condition between 20 W / mol and 150 W / mol; the microwave power of the set microwave generating device 302 is 200 W, 300 W, 400 W, 500 W, 600 W, or any condition between 200 W and 600 W.

[0054] In one or more embodiments of the present invention, in the microwave discharge plasma cracking reaction conditions, the temperature is normal temperature and the pressure is atmospheric pressure.

[0055] In this method, the gas supply system 2 is used to provide hydrocarbon compounds and the discharge medium gas and ensure a stable flow rate.

[0056] In this method, the discharge medium gas includes, but is not limited to, gases with stable chemical properties such as argon and nitrogen that are easy to form discharge plasma.

[0057] In this method, the filler 304 in the microwave discharge plasma cracking system 3 includes, but is not limited to, wave-absorbing materials such as metal needles, metal wires, metal meshes, and activated carbon with a radius of curvature less than or equal to the tip length or radius.

[0058] The operation process of this method includes: 1. putting the filler 304 into the reaction area 303 of the microwave discharge plasma cracking system 3; 2. introducing a discharge medium gas into the microwave reaction chamber of the microwave discharge plasma cracking system 3 to provide a discharge environment for the reaction chamber; 3. adjusting the energy input of the microwave generating device 302, inputting microwaves into the microwave reaction chamber, so that the filler 304 in the microwave reaction chamber continuously discharges, and a stable plasma field is formed around the filler 304; 4. adjusting the gas input, introducing a mixture of methane gas and discharge medium gas into the microwave reaction chamber, and starting the microwave discharge plasma cracking reaction; 5. separating the gas-solid by the separation and sedimentation area 305 of the microwave discharge plasma cracking system 3; 6. regulating the gas circulation volume and times of the gas circulation system 5 according to the product distribution of the gas separation and purification system 6 to regulate the quality of the gas-solid products; 7. collecting the carbon products in the carbon product separation and collection system 4; 8. collecting the gas products after the gas passes through the gas separation and purification system 6.

[0059] Example 1

[0060] Select a pure tungsten tungsten needle with a diameter of 1 mm, a length of 51 mm, and a tip angle of 15°. Assemble the tungsten needle with a quartz sheet having a through hole, and then put it into the reactor 301. Introduce 99.999% argon at a flow rate of 100 ml / min (gas velocity of 0.00657 m / s) for 15 min, then turn on the microwave switch of the microwave generating device 302, adjust the microwave power to 300 W (30 W / mol methane) gear, and after stable discharge for 15 min, switch the gas path, and introduce a mixture of 10% methane + 90% argon into the reactor 301 to react for 20 min. The working temperature is 300 °C, and the reaction pressure is normal pressure.

[0061] Example 2

[0062] Same as Example 1, except that the microwave power is adjusted to 400 W (40 W / mol methane) gear, and the gas flow rate is maintained at 100 ml / min.

[0063] Example 3

[0064] Same as Example 1, except that the microwave power is adjusted to 500 W (50 W / mol methane) gear, and the gas flow rate is maintained at 100 ml / min.

[0065] Example 4

[0066] Same as Example 1, except that the microwave power is adjusted to 300 W gear, and the gas flow rate is adjusted to 200 ml / min (gas velocity of 0.0131 m / s).

[0067] Example 5

[0068] Same as Example 1, except that the microwave power is adjusted to the 300W level and the gas flow rate is adjusted to 300 ml / min (gas velocity is 0.0197 m / s).

[0069] Example 6

[0070] Same as Example 1, except that the gas components of methane and argon are adjusted to 50% methane + 50% argon, the microwave power is maintained at the 300W (150W / mol methane) level, and the gas flow rate remains unchanged at 100 ml / min.

[0071] Example 7

[0072] Same as Example 1, except that a reactor 301 with a smaller cross-sectional radius of the reaction zone 303 is used, the reaction zone 303 is reduced by 20%, the reaction time is adjusted to be reduced by 50%, the microwave power is maintained at the 300W (30W / mol methane) level, and the gas flow rate remains unchanged at 100 ml / min.

[0073] Example 8

[0074] Select coal-based activated carbon particles with a diameter of 2 mm, place the particles into the reactor 301, introduce 99.999% argon at a flow rate of 100 ml / min (gas velocity is 0.007 m / s) for 15 min, then turn on the microwave switch of the microwave generating device 302, adjust the microwave power to the 300W (30W / mol methane) level, after stable discharge for 15 min, switch the gas path, and introduce a mixture of 10% methane + 90% argon into the reactor 301 for reaction for 20 min. The working temperature is 300 °C and the reaction pressure is atmospheric pressure.

[0075] Example 9

[0076] Select block-shaped silicon carbide foam with a diameter of 18 mm, place the silicon carbide foam into the reactor 301, introduce 99.999% argon at a flow rate of 100 ml / min (gas velocity is 0.007 m / s) for 15 min, then turn on the microwave switch of the microwave generating device 302, adjust the microwave power to the 300W (30W / mol methane) level, after stable discharge for 15 min, switch the gas path, and introduce a mixture of 10% methane + 90% argon into the reactor 301 for reaction for 20 min. The working temperature is 300 °C and the reaction pressure is atmospheric pressure.

[0077] Example 10

[0078] Same as Example 1, except that the microwave power is adjusted to the 300W level and the gas flow rate is adjusted to 500 ml / min (gas velocity is 0.0328 m / s).

[0079] Example 11

[0080] Same as Example 1, except that the microwave power is adjusted to the 300 W level and the gas flow rate is adjusted to 50 ml / min (gas velocity is 0.00328 m / s).

[0081] Example 12

[0082] Same as Example 1, except that the microwave power is adjusted to the 200 W (20 W / mol methane) level and the gas flow rate is adjusted to 100 ml / min (gas velocity is 0.00657 m / s).

[0083] Example 13

[0084] Same as Example 1, except that the microwave power is adjusted to the 600 W (60 W / mol methane) level and the gas flow rate is adjusted to 100 ml / min (gas velocity is 0.00657 m / s).

[0085] Example 14

[0086] Same as Example 7, except that the reaction time is the same as that in Example 1.

[0087] Example 15

[0088] Same as Example 1, except that the microwave power is adjusted to the 300 W (30 W / mol ethylene) level. After stable discharge for 15 min, the gas path is switched, and a mixture of 10% ethylene + 90% argon is introduced into the reactor 301 for reaction for 20 min. The working temperature is 300 °C, and the reaction pressure is atmospheric pressure.

[0089] Example 16

[0090] Same as Example 1, except that the microwave power is adjusted to the 300 W (30 W / mol ethane) level. After stable discharge for 15 min, the gas path is switched, and a mixture of 10% ethane + 90% argon is introduced into the reactor 301 for reaction for 20 min. The working temperature is 300 °C, and the reaction pressure is atmospheric pressure.

[0091] The reaction results under the schemes provided in Examples 1 to 16 are shown in Table 1.

[0092] Energy consumed per mol of methane conversion / kJ*mol -1 The calculation formula is:

[0093] ;

[0094] ;

[0095] Among them, SEI is the specific energy input, P is the input power, F is the flow rate of the raw material gas, and 60 is the conversion from minutes to seconds.

[0096] SER is the specific energy requirement, which is the energy required for the complete conversion of 1 mole of methane to produce 1 mole of hydrogen; is the conversion rate of methane or other reactants.

[0097] Table 1. Reaction results under different embodiments

[0098]

[0099] As can be seen from Table 1, using this method and process, high-efficiency cracking of methane > 95% was achieved under low energy consumption and low gas velocity conditions of 300 W, 100 ml / min, that is, 30 W / mol methane and 0.007 m / s. At the same time, controllable conversion of methane with 42% gaseous ethane products and preparation of low-layer graphene with 1 - 2 layers were realized. From the results of Example 15, it can be seen that ethane can be obtained using ethylene as the reactant. From the results of Example 16, it can be seen that using ethane as the reactant can increase the hydrogen production rate; similarly, using the gas circulation system 5 to reintroduce a large amount of ethane products into the microwave discharge plasma cracking system 3 can increase the hydrogen production rate. At the same time, based on this method, a selectivity of approximately 100% for hydrogen can be achieved in the control experiment stage.

[0100] Figure 2 Among them, 300 W, 400 W, and 500 W correspond to Examples 1, 2, and 3 respectively; 100 ml / min, 200 ml / min, and 300 ml / min correspond to Examples 4, 5, and 6 respectively.

[0101] Figure 2 In (a) is the XRD image of the carbon products of different embodiments. The image has peak characteristics at 2θ = 26°, 42°, and 54°, corresponding to the (002), (101), and (004) characteristic peaks of graphite respectively, indicating that the material has a high degree of graphitization.

[0102] Figure 2 In (b) is the Raman image of the carbon products of different embodiments. As shown by the image, the Raman spectrum of the product consists of a D peak, a G peak, and a 2D peak from left to right along the X-axis. The D peak is used for defect characterization, the G peak represents the degree of graphitization, and the shape of the 2D peak can be used to identify the layer thickness. The peak ratio of the D peak and the G peak is used to describe the graphitization degree of the sample, and a lower ID / IG indicates a better graphitization degree. The sharper and higher the intensity of the 2D peak, the lower the number of graphene layers. It can be seen that the graphitization degree is higher and the number of layers is lower under the condition of 400 W.

[0103] Figure 2 In (c) and (d) is the Lorentz fitting of the Raman spectrum Figure 2 The 2D peak of monolayer graphene presents a perfect single peak under the Lorentz fitting. As shown in the figure, the fitting effect is good.

[0104] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for co-producing hydrogen and carbon by pyrolyzing methane with green electricity microwave discharge plasma, characterized in that, Based on a green - electricity - powered microwave - discharge plasma methane cracking system for co - producing hydrogen and carbon, comprising: A green - electricity power supply system for accessing green electricity; A gas supply system for providing a stable mixture of methane gas and discharge medium gas, in which the methane content is 10% - 50%; A gas circulation system for circulating part of the cracked gas; The microwave - discharge plasma cracking system includes: a reactor and a microwave generating device, and the reaction conditions in the reactor are regulated by the microwave generating device; an air inlet connected to the gas supply system is provided at the top of the reactor, a carbon product outlet is provided at the bottom, and an air outlet connected to the gas circulation system is provided on the side; the inside of the reactor is a microwave reaction chamber, a sieve plate is provided above the air outlet, fillers are placed on the sieve plate, the area above the sieve plate is the reaction area, and the area below is the separation and sedimentation area; The fillers are pure tungsten needles with a diameter of 1 mm, a length of 51 mm, and a tip angle of 15°; the cross - sectional radius of the reaction area of the reactor is 9 mm; The method includes the following steps: S1. Place the fillers into the reaction area of the microwave - discharge plasma cracking system; S2. Introduce the discharge medium gas into the microwave reaction chamber of the microwave - discharge plasma cracking system to provide a discharge environment for the microwave reaction chamber; S3. Adjust the energy input of the microwave generating device, input microwaves into the microwave reaction chamber, so that the fillers in the microwave reaction chamber continuously discharge, and a stable plasma field is formed around the fillers; S4. Adjust the gas input of the gas supply system, introduce a mixture of methane gas and discharge medium gas into the microwave reaction chamber, and start the microwave - discharge plasma cracking reaction; generating gas products and low - layer graphene carbon products; S5. The reaction products are separated into gas and solid through the separation and sedimentation area of the microwave - discharge plasma cracking system; the carbon products are collected in the carbon product separation and collection system; the gas products are collected after passing through the gas separation and purification system; In step S4, the microwave - discharge plasma cracking reaction conditions include: the gas velocity is 0.006 m / s - 0.01 m / s; the microwave power of the microwave generating device is 300 W - 500 W; the reaction time is 20 min; If a reactor with a smaller cross - sectional radius of the reaction area is used, the reaction area is reduced by 20%, the reaction time is adjusted to be reduced by 50%, the microwave power is at the 300 W level, the gas flow rate is 100 ml / min, and the methane content in the mixture is 10%; The working temperature is 300 °C and the reaction pressure is atmospheric pressure.

2. The method for co-producing hydrogen and carbon by pyrolyzing methane with green electricity microwave discharge plasma according to claim 1, wherein, In step S4, the microwave - discharge plasma cracking reaction conditions include: adjusting the energy input of the microwave generating device, and the power is any condition between 30 W / mol and 150 W / mol based on methane gas.

3. The method for co-producing hydrogen and carbon by pyrolyzing methane with green electricity microwave discharge plasma according to claim 1, wherein The green - electricity - powered microwave - discharge plasma methane cracking system for co - producing hydrogen and carbon further includes: A carbon product separation and collection system for separating and collecting carbon products and gas products; A gas separation and purification system for separating and purifying hydrogen.

4. The method for co-producing hydrogen and carbon by pyrolyzing methane with green electricity microwave discharge plasma according to claim 3, wherein The green power supply system is electrically connected to the microwave discharge plasma cracking system, and the gas supply system, the carbon product separation and collection system, and the gas circulation system are respectively connected to the microwave discharge plasma cracking system through pipelines. The outlet of the gas circulation system is divided into two branches. One branch is connected to the gas separation and purification system, and the other branch is connected to the microwave discharge plasma cracking system through the connecting pipeline between the gas supply system and the microwave discharge plasma cracking system.

5. The method for co-producing hydrogen and carbon by pyrolyzing methane with green electricity microwave discharge plasma according to claim 3, characterized in that, The discharge medium gas is argon or nitrogen.

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