Preparation method of single-walled carbon nanotube

Abstract

The invention discloses a single-walled carbon nanotube preparation method, which comprises: S1, mixing a composite carbon source, a nano-catalyst and a binder, and sequentially carrying out extrusion molding and sintering to form a composite bar; s2, carrying out plasma catalytic pyrolysis by taking the composite rod as an anode and a pure graphite rod as a cathode to obtain a single-walled carbon nanotube; wherein the composite carbon source comprises high-purity graphite, hard carbon and soft carbon. Through formula design of the composite carbon source, the single-walled carbon nanotube is prepared through plasma catalytic pyrolysis, and the selectivity and yield of the single-walled carbon nanotube are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of carbon nanotube synthesis technology, and in particular to a method for preparing single-walled carbon nanotubes. Background Technology

[0002] Since the beginning of the 21st century, single-atom-layer two-dimensional graphite materials have been hailed as the "black gold" of the 21st century due to their excellent physicochemical properties. Single-walled carbon nanotubes, formed by rolling up a single layer of carbon atoms to create a one-dimensional tubular structure, not only retain the physicochemical properties of single-layer two-dimensional materials but also reduce steric hindrance, improve conductivity directionality and flexibility, exhibiting superior performance in electronics and energy storage. Several mainstream methods exist for producing single-walled carbon nanotubes: chemical vapor deposition (CVD), laser ablation, and arc discharge. However, CVD products often contain multi-walled carbon nanotubes, graphene, fullerenes, amorphous carbon, and other carbon materials, resulting in low selectivity for single-walled carbon nanotubes. Furthermore, the low production efficiency, low product purity, and high cost limit its economic feasibility for large-scale applications. Laser ablation, on the other hand, has extremely low production efficiency and lacks industrial application value.

[0003] Among them, the electric arc discharge method has the potential for industrialization, but in the existing industrialization process of single-walled carbon nanotubes, the electric arc discharge method is difficult to overcome the production rate of 20g or more per hour for a single furnace.

[0004] Therefore, it is necessary to develop a preparation method that can significantly improve the selectivity and yield of single-walled carbon nanotubes. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present invention proposes a method for preparing single-walled carbon nanotubes, which can effectively improve the selectivity, production rate and yield of single-walled carbon nanotubes.

[0006] According to a first aspect of the present invention, a method for preparing single-walled carbon nanotubes is provided, comprising the following steps: S1. The composite carbon source, nano-catalyst and binder are mixed and then extruded and sintered in sequence to form a composite rod. S2. Using the composite rod as the anode and the pure graphite rod as the cathode, plasma catalytic pyrolysis is performed to obtain single-walled carbon nanotubes. The composite carbon source includes high-purity graphite, hard carbon, and soft carbon.

[0007] According to a preferred embodiment of the present invention, the mass ratio of the high-purity graphite, hard carbon, and soft carbon is 1:(0.1~0.5):(0.1~0.9).

[0008] According to a preferred embodiment of the present invention, the mass ratio of the high-purity graphite, hard carbon, and soft carbon is 1:(0.1~0.5):(0.5~0.9).

[0009] According to a preferred embodiment of the present invention, the hard carbon includes at least one of roasted petroleum coke, needle coke, anthracite, coke, coal tar pitch coke, phenolic resin carbon, or biomass hard carbon.

[0010] According to a preferred embodiment of the present invention, the biomass hard carbon refers to carbonization of biomass such as wood, coconut shell, and rice husk.

[0011] According to a preferred embodiment of the present invention, the hard carbon includes at least one of roasted petroleum coke, needle coke, anthracite, coke, coal tar pitch coke, or phenolic resin carbon.

[0012] According to a preferred embodiment of the present invention, the soft carbon includes at least one of coal tar pitch, refined coal tar pitch powder, lignite coke, carbon black, or graphitized mesophase carbon microspheres.

[0013] According to a preferred embodiment of the present invention, the nanocatalyst contains a metal element, wherein the metal element is a transition metal element and / or aluminum.

[0014] According to a preferred embodiment of the present invention, the transition metal element is selected from at least one of iron, cobalt, nickel, yttrium, zinc, chromium, manganese, copper, or molybdenum.

[0015] According to a preferred embodiment of the present invention, the nanocatalyst is selected from one or more of the following: the elemental metal corresponding to the metal element, an alloy formed by two or more of the metal elements, and a compound containing the metal element.

[0016] According to a preferred embodiment of the present invention, the alloy formed by the two or more metallic elements includes Ni4Y, Ni5Y or Ni3Y.

[0017] According to a preferred embodiment of the present invention, the particle size of the nanocatalyst is 1~100 nm.

[0018] According to a preferred embodiment of the present invention, the nanocatalyst accounts for 0.1% to 1% of the molar percentage of the composite carbon source, calculated based on the molar amount of the composite carbon source.

[0019] According to a preferred embodiment of the present invention, the binder accounts for 0.1% to 10% of the total mass of the composite carbon source.

[0020] According to a preferred embodiment of the present invention, the binder comprises at least one of carboxyhydroxycellulose, furan resin, chitosan, starch, polyacrylic acid resin, or polyacrylic acid.

[0021] According to a preferred embodiment of the present invention, the sintering temperature is 900℃~1200℃.

[0022] According to a preferred embodiment of the present invention, the gas used in the plasma catalytic pyrolysis is at least one of helium, argon and neon, and the gas pressure is 1~200 kPa; the discharge arc voltage of the plasma catalytic pyrolysis is 10~40V and the current is 10~400A.

[0023] The preparation method according to embodiments of the present invention has at least the following beneficial effects: This invention utilizes a composite carbon source formulation design to prepare single-walled carbon nanotubes via plasma catalytic pyrolysis, significantly improving the selectivity and yield of single-walled carbon nanotubes. A single furnace can achieve a production rate of 20 g / h or higher, with the product containing over 54% single-walled nanotubes.

[0024] This is because the high-purity graphite of this invention provides an ordered and stable flow of carbon atoms as the main carbon source; soft carbon is highly reactive and readily reacts, providing initial kinetic energy for synthesis; and hard carbon has a slow reaction rate, providing a stable backup carbon source for synthesis. This, in turn, significantly improves yield and exhibits high selectivity.

[0025] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is the Raman spectrum of the single-walled carbon nanotube of Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the single-walled carbon nanotubes of Embodiment 1 of the present invention; Figure 3 This is a thermogravimetric analysis diagram of a single-walled carbon nanotube from Embodiment 1 of the present invention. Detailed Implementation

[0027] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0028] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0029] In some embodiments of the present invention, a method for preparing single-walled carbon nanotubes is provided, comprising the following steps: S1. The composite carbon source, nano-catalyst and binder are mixed and then extruded and sintered in sequence to form a composite rod. S2. Using composite rods as the anode and pure graphite rods as the cathode, plasma catalytic pyrolysis is performed to obtain single-walled carbon nanotubes. The composite carbon source includes high-purity graphite, hard carbon, and soft carbon.

[0030] Understandably, this invention, through the formulation of a composite carbon source, prepares single-walled carbon nanotubes via plasma catalytic pyrolysis, significantly improving the selectivity and yield of single-walled carbon nanotubes. A single furnace can achieve a production rate of 20 g / h or higher, with the product containing over 54% single-walled nanotubes.

[0031] This is because the high-purity graphite of this invention provides an ordered and stable flow of carbon atoms as the main carbon source; soft carbon is highly reactive and readily reacts, providing initial kinetic energy for synthesis; and hard carbon has a slow reaction rate, providing a stable backup carbon source for synthesis. This, in turn, significantly improves yield and exhibits high selectivity.

[0032] In some embodiments of the present invention, the mass ratio of high-purity graphite, hard carbon, and soft carbon is 1:(0.1~0.5):(0.1~0.9). For example, the mass ratios are 1:0.1:0.9, 1:0.2:0.8, 1:0.3:0.7, 1:0.4:0.6, 1:0.5:0.5, 1:0.3:0.4, 1:0.5:0.3, 1:0.5:0.2, or any sub-range of any two of the above values. Therefore, when the mass ratio of high-purity graphite, hard carbon, and soft carbon in the composite carbon source is within the above range, single-walled carbon nanotubes exhibit good yield and selectivity.

[0033] In some embodiments of the present invention, the mass ratio of high-purity graphite, hard carbon, and soft carbon is 1:(0.1~0.5):(0.5~0.9). For example, the mass ratio is 1:0.1:0.9, 1:0.2:0.8, 1:0.3:0.7, 1:0.4:0.6, 1:0.5:0.5, or any sub-range of any two of the above values. Therefore, when the mass ratio of high-purity graphite, hard carbon, and soft carbon in the composite carbon source is within the above range, single-walled carbon nanotubes exhibit better yield and selectivity.

[0034] In some embodiments of the present invention, hard carbon includes at least one of roasted petroleum coke, needle coke, anthracite, coke, coal tar pitch coke, phenolic resin carbon, or biomass hard carbon.

[0035] In some embodiments of the present invention, biomass hard carbon refers to carbonization of biomass such as wood, coconut shells, and rice husks.

[0036] In some embodiments of the present invention, the hard carbon includes at least one of roasted petroleum coke, needle coke, anthracite, coke, coal tar pitch coke, or phenolic resin carbon.

[0037] In some embodiments of the present invention, soft carbon includes at least one of coal tar pitch, refined coal tar pitch powder, lignite coke, carbon black, or graphitized mesophase carbon microspheres.

[0038] In some embodiments of the present invention, the nanocatalyst contains a metal element, which is a transition metal element and / or aluminum.

[0039] In some embodiments of the present invention, the transition metal element is selected from at least one of iron, cobalt, nickel, yttrium, zinc, chromium, manganese, copper, or molybdenum.

[0040] In some embodiments of the present invention, the nanocatalyst is selected from one or more of the following: the elemental metal corresponding to the metal element, the alloy formed by two or more of the metal elements, and the compound containing the metal element.

[0041] In some embodiments of the present invention, the nanocatalyst is a mixture of two or more metal elements corresponding to the aforementioned metal elements, preferably a mixture of two or more transition metal elements corresponding to the aforementioned metal elements. The present invention does not impose any particular requirement on the mixing ratio between the metal elements in the mixture; for example, it can be a mixture of nickel and yttrium, wherein the molar ratio of nickel to yttrium in the nickel and yttrium mixture can be 3 to 5:1, specifically 3:1, 4:1, or 5:1. As one embodiment of the present invention, the nanocatalyst is an alloy formed from two or more metal elements.

[0042] In some embodiments of the present invention, the alloy formed by two or more metallic elements includes Ni4Y, Ni5Y or Ni3Y.

[0043] In this invention, the alloy-form nanocatalyst has a lower melting point and weaker thermal conductivity than a single metal, which makes it easier to trigger the reaction (the lower melting point allows it to co-evaporate with carbon atoms at a lower temperature, and the weaker thermal conductivity makes it easier to concentrate energy), and the alloy can achieve a more uniform composite of metal elements.

[0044] In some embodiments of the present invention, the nanocatalyst is a mixture of the alloy and the elemental metal. The alloy can be Ni4Y, and the elemental metal can be aluminum, zinc, chromium, manganese, copper, or molybdenum. The molar ratio of the alloy to the elemental metal can be (90~99.5):(10:0.5), such as 99.5:0.5, 99:1, 98:2, 95:5, or 90:10. The present invention does not have any particular requirements regarding the source of the nanocatalyst; it can be prepared using commercially available products or methods well known to those skilled in the art.

[0045] In some embodiments of the present invention, the particle size of the nanocatalyst is 1-100 nm. For example, the particle size includes 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or any sub-range of any two of the above values. The present invention uses a nanocatalyst, which, compared with micron-sized large particle catalysts, can reduce the content of carbon impurities (such as amorphous carbon, or even fullerenes) of non-single-walled carbon nanotubes in the product; in addition, using a nanocatalyst can reduce the amount of catalyst used, thereby increasing the yield of single-walled carbon nanotubes in the product.

[0046] In some embodiments of the present invention, the particle size of the nanocatalyst is 1 to 50 nm. For example, the particle size includes 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, or any subrange consisting of two of the above values.

[0047] In some embodiments of the present invention, the molar percentage of the nanocatalyst in the composite carbon source is 0.1% to 1%, calculated based on the molar amount of the composite carbon source. For example, it is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any sub-range of any two of the above values.

[0048] Too low a catalyst content (<0.1%) makes it difficult to ensure sufficient active sites in the arc region, leading to a decrease in SWCNT yield and selectivity. Too high a catalyst content (>1%) easily leads to catalyst agglomeration, the formation of multi-walled nanotubes and amorphous carbon impurities, affecting single-walled yield and purity. Therefore, within the scope of this invention, high-density active sites can be achieved while minimizing agglomeration, promoting bidispersed and highly selective growth of single-walled carbon nanotubes.

[0049] In some embodiments of the present invention, the binder accounts for 0.1% to 10% of the total mass of the composite carbon source. For example, it is 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any sub-range of any two of the above values.

[0050] When the binder content is too low (<0.1%), it is difficult to effectively bind the carbon powder, resulting in a loose composite rod structure, low mechanical strength, decreased formability and sintering density, affecting anode stability and subsequent stable arc discharge. Conversely, when the binder content is too high (>10%), it causes impurity accumulation, increased porosity, and carbon source dilution, leading to a porous composite rod structure, decreased conductivity, and the accumulation of useless byproducts, ultimately affecting the purity and yield of single-walled carbon nanotubes. Therefore, within the scope of this invention, while ensuring forming density and mechanical strength, it also considers anode purity and discharge performance, achieving optimal single-walled carbon nanotube quality and yield.

[0051] In some embodiments of the present invention, the binder includes at least one selected from carboxyhydroxycellulose, furan resin, chitosan, starch, polyacrylic acid resin, and polyacrylic acid.

[0052] In some embodiments of the present invention, the sintering temperature is 900°C to 1200°C. For example, the temperature includes 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, or any sub-range consisting of any two of the above values.

[0053] In some embodiments of the present invention, the gas used for plasma catalytic pyrolysis is at least one of helium, argon, and neon, and the gas pressure is 1~200 kPa, for example including 1 kPa, 20 kPa, 50 kPa, 70 kPa, 100 kPa, 150 kPa, or 200 kPa; the discharge arc voltage of plasma catalytic pyrolysis is 10~40V, for example including 10V, 20V, 30V, or 40V; and the current is 10~400A, for example including 10A, 20A, 50A, 80A, 100A, 150A, 200A, 250A, 300A, 350A, 400A, or any sub-range of two of the above values.

[0054] In this invention, high-purity graphite refers to graphite with a purity of 99.99% or higher.

[0055] In this invention, the embodiments and comparative examples use some of the following raw materials: Nanocatalyst A: Nano Ni4Y alloy catalyst (particle size 5nm); Nanocatalyst B: Nano Ni4Y:Al (molar ratio 99:1) alloy catalyst (particle size 5nm); all purchased from Shanghai Muran Industrial Development Co., Ltd. High-purity graphite: high-purity artificial graphite; soft carbon: refined tar pitch powder; hard carbon: needle coke; all purchased from Hebei Qunbang Chemical Co., Ltd. Composite carbon source A: Mixed according to the following ratios: 100g, 20g and 80g of high-purity graphite, soft carbon and hard carbon; Composite carbon source B: Mixed according to the ratio of high-purity graphite: soft carbon: hard carbon in the proportions of 100g, 10g and 90g. Composite carbon source C: Mixed according to the ratio of high-purity graphite: soft carbon: hard carbon of 100g, 30g and 70g; Composite carbon source D: Mixed according to the following ratios: 100g, 40g and 60g of high-purity graphite, soft carbon and hard carbon; Composite carbon source E: Mixed according to the ratio of high-purity graphite: soft carbon: hard carbon in 100g, 50g and 50g respectively; Composite carbon source F: Mixed according to the ratios of 100g, 50g and 30g of high-purity graphite, soft carbon and hard carbon; Composite carbon source G: Mixed according to the ratio of 100g of high-purity graphite to 100g of soft carbon; Composite carbon source H: Mixed with 100g each of high-purity graphite and hard carbon.

[0056] Example 1 This example provides a method for preparing single-walled carbon nanotubes, including the following steps: S1. The various substances in composite carbon source A are mechanically stirred three times at 500 r / min for 10 s each time; then 20 g of carboxyhydroxy cellulose is added and stirred three times again at 1000 r / min for 10 s each time; nano-catalyst A is added according to the molar ratio (C:Ni4Y is 99.2:0.8), and the mixture is extruded into a blank with a diameter of 20 mm. The blank is placed in a high-temperature furnace under argon protection and sintered at 1000 °C for 4 h to obtain the anode composite rod. S2. Place the anode composite rod prepared in step S1 into a plasma generator. The cathode is a pure graphite rod with a diameter of 40 mm. The plasma gas used is a mixture of helium and neon, with helium accounting for 99.9% of the volume and the gas pressure being 70 kPa. The discharge current is 100 A, the voltage is 30 V, and the discharge time is 5 min, thus obtaining crude single-walled carbon nanotubes.

[0057] Furthermore, the single-walled carbon nanotubes of this embodiment were subjected to Raman spectroscopy, and the results are as follows: Figure 1 As shown, in the low wavenumber region (typically 100-400 cm⁻¹) - ¹) One or more distinct characteristic peaks were observed, which are radial breathing mode (RBM) peaks, indicating that carbon nanotubes with a well-defined single-walled tubular structure were successfully prepared.

[0058] Furthermore, the single-walled carbon nanotubes of the present invention were subjected to SEM testing, and the results are as follows: Figure 2 As shown, the presence of numerous <50 nm bundles, no obvious surface layering, and extremely long, coiled fiber networks under SEM confirms the successful preparation of carbon nanotubes with a distinct single-walled tubular structure.

[0059] Furthermore, thermogravimetric analysis (TGA) was performed on the single-walled carbon nanotubes of the present invention, and the results are as follows: Figure 3 As shown, the crude single-walled carbon nanotubes (SWCNTs) were heated in a gaseous atmosphere of 5% O2 + air. The percentage of SWCNTs in the total mass was calculated as follows: SWCNT percentage of carbon component = m 碳 / m SWCNT ×100%; Where, m SWCNT : Weight loss mass of the SWCNT step corresponding to the TGA (corresponding temperature is 400~800℃).

[0060] m 碳 Total weight loss of all carbon components in the sample (i.e., m0-m) 灰 ); m0: Total initial mass of the sample; m 灰 Residual ash (inorganic components such as catalysts); The TG data for Example 1 were calculated using the above formula, and SWCNT accounted for 66.7% of the total carbon composition.

[0061] Example 2 This example provides a method for preparing single-walled carbon nanotubes, which is the same as that in Example 1, except that composite carbon source B is used instead of composite carbon source A.

[0062] Example 3 This example provides a method for preparing single-walled carbon nanotubes, which is the same as that in Example 1, except that composite carbon source C is used instead of composite carbon source A.

[0063] Example 4 This example provides a method for preparing single-walled carbon nanotubes, which is the same as that in Example 1, except that composite carbon source D is used instead of composite carbon source A.

[0064] Example 5 This example provides a method for preparing single-walled carbon nanotubes, which is the same as that in Example 1, except that composite carbon source E is used instead of composite carbon source A.

[0065] Example 6 This example provides a method for preparing single-walled carbon nanotubes, which is the same as that in Example 1, except that composite carbon source F is used instead of composite carbon source A.

[0066] Example 7 This example provides a method for preparing single-walled carbon nanotubes, which is the same as that in Example 1, except that nanocatalyst B is used instead of nanocatalyst A.

[0067] Examples 8-12 This example provides a series of methods for preparing single-walled carbon nanotubes, which are the same as those in Example 1, except that the types of soft carbon and hard carbon are different, as shown in Table 1.

[0068] Table 1

[0069] Comparative Example 1 This example provides a method for preparing single-walled carbon nanotubes, which is the same as that in Example 1, except that composite carbon source G is used instead of composite carbon source A.

[0070] Comparative Example 2 This example provides a method for preparing single-walled carbon nanotubes, which is the same as that in Example 1, except that composite carbon source H is used instead of composite carbon source A.

[0071] Results Test Record the corresponding time t (representing the total time for preparing single-walled carbon nanotubes), the mass of the anode rod consumed (m0), and the mass of the product collected (m0) in the embodiments and comparative examples of this invention. c ), calculate the yield of single-walled carbon nanotubes (m c / m0×100%), production rate (m c The content of single-walled carbon nanotubes in the product (obtained using the calculation method described in Example 1 above) is shown in Table 2.

[0072] Table 2

[0073] As shown in Table 2, this invention significantly improves the selectivity and yield of single-walled carbon nanotubes by using a composite carbon source formulation and plasma-catalyzed pyrolysis. A single furnace can achieve a production rate of 20 g / h or higher, and the product contains over 54% single-walled nanotubes.

[0074] This is because the high-purity graphite of this invention provides an ordered and stable flow of carbon atoms as the main carbon source; soft carbon is highly reactive and readily reacts, providing initial kinetic energy for synthesis; and hard carbon has a slow reaction rate, providing a stable backup carbon source for synthesis. This, in turn, significantly improves yield and exhibits high selectivity.

[0075] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing single-walled carbon nanotubes, characterized in that, Includes the following steps: S1. The composite carbon source, nano-catalyst and binder are mixed and then extruded and sintered in sequence to form a composite rod. S2. Using the composite rod as the anode and the pure graphite rod as the cathode, plasma catalytic pyrolysis is performed to obtain single-walled carbon nanotubes. The composite carbon source includes high-purity graphite, hard carbon, and soft carbon.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the high-purity graphite, hard carbon, and soft carbon is 1:(0.1~0.5):(0.1~0.9).

3. The preparation method according to claim 1 or 2, characterized in that, The mass ratio of the high-purity graphite, hard carbon, and soft carbon is 1:(0.1~0.5):(0.5~0.9).

4. The preparation method according to claim 1, characterized in that, The hard carbon includes at least one of roasted petroleum coke, needle coke, anthracite, coke, coal tar pitch coke, phenolic resin carbon, or biomass hard carbon.

5. The preparation method according to claim 1, characterized in that, The soft carbon includes at least one of coal tar pitch, refined coal tar pitch powder, lignite coke, carbon black, or graphitized mesophase carbon microspheres.

6. The preparation method according to claim 1, characterized in that, The nanocatalyst contains a metal element, which is a transition metal element and / or aluminum. Preferably, the transition metal element is selected from at least one of iron, cobalt, nickel, yttrium, zinc, chromium, manganese, copper, or molybdenum.

7. The preparation method according to claim 1, characterized in that, Based on the molar amount of the composite carbon source, the nanocatalyst accounts for 0.1% to 1% of the molar percentage of the composite carbon source.

8. The preparation method according to claim 1, characterized in that, The binder accounts for 0.1% to 10% of the total mass of the composite carbon source.

9. The preparation method according to claim 1, characterized in that, The binder includes at least one of carboxyhydroxycellulose, furan resin, chitosan, starch, polyacrylic acid resin, or polyacrylic acid.

10. The preparation method according to claim 1, characterized in that, The gas used in the plasma catalytic pyrolysis is at least one of helium, argon and neon, and the gas pressure is 1~200kPa; the discharge arc voltage of the plasma catalytic pyrolysis is 10~40V and the current is 10~400A.

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