Tubular compact metal nickel film for methane reforming as well as preparation and application of tubular compact metal nickel film
By preparing a multi-channel tubular dense nickel membrane, the problems of low stiffness and poor catalytic effect of traditional single-channel nickel membranes were solved, achieving efficient hydrogen separation and improved catalytic performance, which is suitable for methane reforming reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-13
- Publication Date
- 2026-03-10
AI Technical Summary
Traditional single-channel nickel film structures have low stiffness, poor catalytic reaction effect, and are prone to bending and deformation under high temperature conditions, which limits their application in methane reforming reactions.
A multi-channel tubular dense nickel film preparation method is adopted, which forms a dense metal structure by high-temperature sintering in a hydrogen atmosphere, with nickel nanoparticles precipitated on the inner surface, and combined with a support structure to enhance the rigidity of the film, thereby realizing the integration of catalysis and separation.
It significantly improves hydrogen permeation and purity, enhances the mechanical strength and thermal shock resistance of the membrane, and improves catalytic performance and stability, making it suitable for methane reforming reactions.
Smart Images
Figure CN121623595A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of metal membrane catalytic hydrogen permeation, in particular to a tubular dense metal nickel membrane for methane reforming and its preparation and application. BACKGROUND
[0002] Methane reforming is the main way of large-scale hydrogen production in industry. The traditional methane reforming process for hydrogen production requires high temperature to maintain, has huge energy consumption, and the reaction is limited by thermodynamic equilibrium. The product is a mixed gas, which must rely on subsequent complex and expensive separation and purification steps (such as pressure swing adsorption) to obtain high-purity hydrogen, increasing the system complexity and cost. And long-term operation is prone to performance degradation due to carbon deposition or sintering.
[0003] Metal membrane separation technology, especially dense metal nickel membrane, is widely used in hydrogen separation and purification process due to its excellent hydrogen selectivity and high temperature stability. Traditional metal nickel membrane usually adopts a single-channel tubular structure. In order to achieve sufficient density and withstand operating pressure, the tube wall is usually designed to be thick, which not only increases the mass transfer resistance of hydrogen and reduces the permeation flux, but also makes the radial rigidity and axial rigidity of the tube body seriously mismatched, showing significant high asymmetry. In addition, the surface of the traditional single-channel nickel membrane is relatively flat, and the number of exposed active sites is limited, which makes the catalytic reaction effect low. As the core component of the membrane reactor, the overall structure has low rigidity and the material is soft, which is prone to bending, deformation or even collapse during handling, loading or system operation, which further limits the large-scale commercial application. SUMMARY
[0004] In view of the shortcomings of the prior art, the present application provides a tubular dense metal nickel membrane for methane reforming and its preparation and application, which solves the technical problems of low structural rigidity and poor catalytic reaction effect of the existing single-channel nickel membrane.
[0005] The technical solution adopted by the present application is as follows: The present application provides a preparation method of a tubular dense metal nickel membrane for methane reforming, comprising: Dissolve polymethyl methacrylate into N-methyl-2-pyrrolidone, mechanically stir at 50-100℃, then add raw materials, continue to stir and disperse uniformly to obtain a membrane solution; Transfer the membrane solution to a multi-channel metal spinning head device to extrude at room temperature to obtain a nickel membrane precursor; Sinter the nickel membrane precursor in a hydrogen atmosphere at high temperature to obtain a tubular dense membrane; The raw material is metal nickel powder or metal nickel oxide powder; The tubular dense membrane is a circular tube structure with multiple channels inside, and the circular tube structure has a support structure at a central position, so that the tube wall of the circular tube structure is thinned. The inner surface of the tubular dense membrane is formed with uniformly distributed precipitated nickel nanoparticles, the particle size of the nickel nanoparticles is 100-500 nm, and the nickel nanoparticles are in a hemispherical protrusion or grain epitaxial structure.
[0006] As a preferred technical solution: The preparation method further comprises: changing the type of the raw material, the temperature rising program and temperature of the high-temperature sintering, and controlling the number and size of the nickel nanoparticles.
[0007] The particle size of the metal nickel powder and the metal nickel oxide powder is 1-5 um.
[0008] The mass percentage of the raw material, polymethyl methacrylate and N-methyl-2-pyrrolidone is: (70-75 wt.%): (5-10 wt.%): (20-25 wt.%).
[0009] The tube wall of the circular tube structure is 50 um.
[0010] The high-temperature sintering of the nickel film precursor in a hydrogen atmosphere comprises: Rising from room temperature to 1200-1400℃ at a rate of 2-3 ℃ / min -1 , and keeping the temperature for a period of time, and then cooling to room temperature at a rate of 3 ℃ / min -1 to complete sintering.
[0011] The hydrogen atmosphere uses H2 and Ar mixed gas, and the H2 concentration is 5-99 mol%.
[0012] The application also provides a tubular dense metal nickel film for methane reforming prepared according to the preparation method.
[0013] The application also provides a use method of the tubular dense metal nickel film for methane reforming, comprising: Connecting the tubular dense membrane to alumina corundum pipes at both ends respectively, and then loading into a quartz glass pipe, one end of the corundum pipe extending out of the quartz glass pipe and being connected to an external gas source to assemble into a reactor; Passing methane reaction gas into the inside of the tubular dense membrane through the corundum pipe, and passing inert gas into the quartz glass pipe to carry out methane dry reforming or wet reforming reaction.
[0014] The methane reaction gas is a mixed gas of methane and water vapor, or a mixed gas of methane and carbon dioxide.
[0015] The technical solution of the application can achieve at least part of the following beneficial effects: The preparation method of the present application uses an extrusion method to prepare a multi-channel nickel film precursor. On the one hand, the high-temperature sintering process is always in a hydrogen atmosphere, so that the precursor does not need to be pre-sintered in air, does not go through the process of oxidation and reduction, and fully sintered to form a dense metal structure matrix, and promotes the growth and rearrangement of the crystal grains during the densification process, causing the inner surface of the dense metal structure matrix to precipitate nanometer-sized nickel particles, i.e., nickel nanoparticles. The small nickel nanoparticles have more low-coordination surface Ni atom sites, which can enhance the adsorption and C-H bond activation ability of CH4 molecules on the Ni surface, and there is a lattice distortion and stress zone at the interface between the nickel nanoparticles and the dense metal structure matrix, forming a wider lattice gap that is conducive to the dissociation of hydrogen atoms into the Ni lattice. Thus, the catalytic performance of the dense metal nickel film in the methane reforming reaction is significantly improved, and the purity of the separated hydrogen can reach more than 99%. On the other hand, compared with a single-channel film structure, the dense metal nickel film of the present application has multiple channels inside and forms a support structure in the middle, which significantly reduces the thickness of the outer dense film layer and shortens the diffusion path of hydrogen atoms in the film, thereby effectively improving the hydrogen permeation amount and permeation rate. At the same time, the middle support structure can enhance the rigidity and stability of the film, significantly improve the mechanical strength and thermal shock resistance of the film body, and ensure long-term stable operation under high-temperature conditions.
[0016] By changing the types of raw materials, sintering temperature and temperature rising program, the present application can realize the controllable adjustment of the number and size of the nickel nanoparticles, meeting different methane reforming catalysis needs.
[0017] The present application preferably uses metal nickel powder with higher reducibility as a raw material for preparation, which can accelerate the sintering and lattice connection between particles, form smaller and more numerous Ni grains, and appropriate reduction of the heating rate and increase of the reduction temperature can prolong the balance process of particle surface diffusion and reduction, avoiding excessive grain growth, all of which can reduce the grain size.
[0018] The tubular dense metal nickel film of the present application has the functions of catalysis and simultaneous hydrogen generation during application, forming a process intensification function of "reaction-separation integration". During the reaction, the *H activated on the Ni surface can quickly dissolve into the Ni lattice and diffuse across the membrane, and the H2 molecules recombined outside the membrane are quickly carried away by inert gas. This reaction-separation coupling mechanism effectively removes the hydrogen product in the reaction system, breaking the reaction equilibrium limitation of traditional reforming reactions.
[0019] The dense nickel film of this invention is applicable to both dry reforming of methane and carbon dioxide and wet reforming of methane and steam. Under the adsorption and activation of Ni surface particles, it can promote the gradual dehydrogenation of CH4 and activate CO2 or H2O molecules, and also achieve dynamic regeneration of grains through surface oxidation-reduction cycles. Even under high temperature and carbon deposition environments, it maintains stable catalytic activity, significantly improving the film's resistance to poisoning under complex atmospheres and high temperature conditions.
[0020] Other features and advantages of the invention will be set forth in the following description or may be learned by practicing the invention. Attached Figure Description
[0021] Figure 1 The image shows a cross-sectional SEM image of a four-channel tubular dense membrane prepared according to an embodiment of the present invention.
[0022] Figure 2 SEM image of the inner surface of the four-channel tubular dense membrane prepared in an embodiment of the present invention.
[0023] Figure 3 A structural diagram of the reactor formed by the four-channel tubular dense membrane assembly prepared in this embodiment of the invention.
[0024] Explanation of reference numerals in the attached diagram: 1. Tubular dense membrane; 2. Corundum tube; 3. Quartz glass tube. Detailed Implementation
[0025] The specific embodiments of the present invention are described below with reference to the accompanying drawings.
[0026] This application discloses a method for preparing a tubular dense nickel film for methane reforming, comprising: Polymethyl methacrylate was dissolved in N-methyl-2-pyrrolidone and mechanically stirred at 50-100 °C for a period of time. Then the raw material was added and stirred for a period of time to make the raw material particles uniformly dispersed to obtain the membrane solution. The membrane solution was transferred to a multi-channel metal spinning head device and extruded at room temperature to obtain a nickel film precursor. The nickel film precursor was sintered at high temperature in a hydrogen atmosphere to obtain a tubular dense film. The raw material is metallic nickel powder or metallic nickel oxide powder, preferably metallic nickel powder; The tubular dense membrane is a circular tube structure with multiple channels inside. The circular tube structure has a supporting structure at its center, which makes the tube wall thinner. The shape of the internal channels of the circular tube structure matches the structure of the spinning head, and the cross-section of the channels is preferably circular. The inner surface of the tubular dense membrane is covered with uniformly distributed precipitated nickel nanoparticles, the nanoparticles having a diameter of 100–500 nm and exhibiting hemispherical protrusions or epitaxial grain structures. It is understood that the inner surface includes the inner walls of all internal channels.
[0027] The nickel film precursor of this application is kept in a hydrogen atmosphere during high-temperature sintering, which eliminates the need for pre-sintering in air and avoids the oxidation-reduction process, allowing for complete sintering to form a dense metal structure matrix. This densification process promotes grain growth and rearrangement, resulting in the precipitation of 100-nanometer-sized nickel particles on the inner surface of the dense metal structure matrix. For its structure, please refer to [link to relevant documentation]. Figure 1 Nickel nanoparticles have more low-coordination surface Ni atomic sites, which can enhance the adsorption of CH4 molecules on the Ni surface and the activation of C–H bonds. At the interface between the nickel nanoparticles and the dense metal structure matrix, there are lattice distortion and stress regions, forming wider lattice gaps, which is conducive to the dissociation of hydrogen atoms into the Ni lattice.
[0028] As a preferred embodiment, the multi-channel metal spinning head has four channels, resulting in a tubular dense membrane that is a circular tube structure with four internal channels. Due to the supporting structure, the wall of the circular tube structure is thinned to approximately 50 micrometers. Figure 1 As shown.
[0029] As a preferred method, the number and size of the nickel nanoparticles can be controlled by changing the type of raw materials, sintering temperature and heating program, so as to obtain different tubular dense membranes to meet different methane reforming catalytic requirements.
[0030] As a preferred embodiment, the particle size of the nickel powder and nickel oxide powder is 1-5 μm.
[0031] As a preferred embodiment, the mass percentages of the raw materials, polymethyl methacrylate, and N-methyl-2-pyrrolidone are: (70-75 wt.%): (5-10 wt.%): (20-25 wt.%).
[0032] As a preferred embodiment, the step of sintering the nickel film precursor at high temperature in a hydrogen atmosphere includes: At 2-3 ℃ / min -1 The temperature was increased from room temperature to 1200-1400℃ at a rate that was maintained for a period of time, and then increased at a rate of 3℃ / min. -1 Sintering is completed by rapidly cooling to room temperature.
[0033] As a preferred embodiment, the hydrogen atmosphere is a mixture of H2 and Ar, with an H2 concentration of 5-99 mol.
[0034] See Figure 3This application also provides a method for preparing a tubular dense nickel film for methane reforming, the method for preparing the dense nickel film obtained therefrom, and a method for applying the film, the application method comprising: The tubular dense membrane 1 is connected to an alumina corundum tube 2 at both ends, and the connection is sealed with ceramic glue. Then it is installed in a quartz glass tube 3 to assemble a micro reactor. One end of the corundum tube 2 extends out of the quartz glass tube 3 for connection with an external gas source. The quartz glass tube 3 is provided with an inlet end and an outlet end. Methane reaction gas is introduced into the tubular dense membrane 1 through the corundum tube 2, and inert gas is introduced into the quartz glass tube through the gas inlet end to carry out the methane dry reforming or wet reforming reaction.
[0035] As a preferred embodiment, the methane reaction gas is a mixture of methane and water vapor, or a mixture of methane and carbon dioxide.
[0036] In dry reforming, nickel nanoparticles on the inner surface of the tubular dense membrane facilitate the gradual dehydrogenation of CH4 and the dissociation of CO2 into CO and O, which promotes the reaction. It also facilitates the dissolution and diffusion of *H within the membrane. The same principle applies to wet reforming, where H2O adsorption and dissociation into OH and H, which also promote the reaction and the diffusion of *H.
[0037] The following specific examples 1 to 3 further illustrate the preparation method of the tubular dense nickel film for methane reforming in this application. Example 1:
[0038] This embodiment describes a method for preparing a tubular dense nickel film for methane reforming, comprising the following steps: S1. Weigh 5g of the organic polymer polymethyl methacrylate (PMMA) and dissolve it in 25g of N-methyl-2-pyrrolidone (NMP). Stir mechanically at 50 ℃ for 10 h to ensure that the PMMA is completely dissolved and forms a polymer solution. Stir 70g of nickel oxide powder with an average particle size of 5 μm for 24 h to ensure that the nickel powder particles are uniformly dispersed to obtain a film solution. S2. The membrane solution is transferred to a four-channel metal spinning head device and extruded at room temperature to obtain a nickel film precursor. The precursor is straightened, dried at room temperature, and then cut into 15cm pieces.
[0039] S3. Place the precursor obtained in S2 into an atmosphere furnace, and introduce a 5 mol% H2-Ar mixed gas into the furnace tube at a rate of 3°C / min. -1 The temperature was increased from room temperature to 1200 °C and held for 5 hours to obtain a dense hollow fiber membrane; finally, it was heated at 3 °C / min in an atmosphere containing H2. -1 Sintering was completed by cooling to room temperature, forming a four-channel tubular dense film N1, and A nanoparticles were obtained on the inner surface, such as...Figure 2 As shown in (a). Example 2:
[0040] This embodiment describes a method for preparing a tubular dense nickel film for methane reforming, comprising the following steps: S1. Weigh 5g of organic polymer polymethyl methacrylate (PMMA) and dissolve it in 20g of N-methyl-2-pyrrolidone (NMP). Stir mechanically at 50 ℃ for 10 h to ensure that PMMA is completely dissolved and forms a polymer solution. Stir 75g of metallic nickel powder with an average particle size of 1 μm for 24 h to ensure that the nickel powder particles are uniformly dispersed to obtain a film solution.
[0041] S2. The membrane solution is transferred to a four-channel metal spinning head device and extruded at room temperature to obtain a nickel film precursor. The precursor is straightened, dried at room temperature, and then cut into 15cm pieces.
[0042] S3. Place the precursor obtained in S2 into an atmosphere furnace, and introduce a 99 mol% H2-Ar mixed gas into the furnace tube at a rate of 3 °C / min. -1 The temperature was increased from room temperature to 1300 °C and held for 5 hours to obtain a dense hollow fiber membrane. Finally, it was heated at 3 °C / min in an H2 atmosphere. -1 Sintering was completed by cooling to room temperature, forming a four-channel tubular dense N2 film, and B nanoparticles were obtained on the inner surface, such as... Figure 2 As shown in (b). Example 3:
[0043] This embodiment describes a method for preparing a tubular dense nickel film for methane reforming, comprising the following steps: S1. Weigh 5g of organic polymer polymethyl methacrylate (PMMA) and dissolve it in 20g of N-methyl-2-pyrrolidone (NMP). Stir mechanically at 50 ℃ for 10 h to ensure that PMMA is completely dissolved and forms a polymer solution. Stir 75g of metallic nickel powder with an average particle size of 1 μm for 24 h to ensure that the nickel powder particles are uniformly dispersed to obtain a film solution.
[0044] S2. The membrane solution is transferred to a four-channel metal spinning head device and extruded at room temperature to obtain a nickel film precursor. The precursor is straightened, dried at room temperature, and then cut into 15cm pieces.
[0045] S3. Place the precursor obtained in S2 into an atmosphere furnace, and introduce a 99 mol% H2-Ar mixed gas into the furnace tube at a rate of 2 °C / min. -1 The temperature was increased from room temperature to 1400 °C and held for 5 hours to obtain a dense hollow fiber membrane. Finally, it was heated at 3 °C / min in an H2 atmosphere. -1Sintering was completed by cooling to room temperature, forming a four-channel tubular dense film N3, and C nanoparticles were obtained on the inner surface, such as... Figure 2 As shown in (c).
[0046] Comparative analysis shows that the B nanoparticles in the four-channel tubular dense membrane N2 obtained in Example 2 are smaller in size and more uniformly dispersed than the A nanoparticles in the four-channel tubular dense membrane N1 obtained in Example 1. Similarly, the C nanoparticles in the four-channel tubular dense membrane N3 obtained in Example 3 are smaller in size and more uniformly dispersed than both the A and B nanoparticles. This demonstrates that the directional control of nanoparticles can be achieved through the synergistic adjustment of temperature, atmosphere, and raw material type.
[0047] The following specific examples 4 to 6 further illustrate the application method of the tubular dense nickel film for methane reforming in this application. Example 4:
[0048] This embodiment describes a method for applying a tubular dense nickel film for methane reforming, specifically including: 4.1 Wet reforming: The four-channel tubular dense membrane N1 prepared in Example 1 was encapsulated in a quartz glass tube to form reactor N1. A first methane reaction gas was introduced into the four-channel tubular dense membrane N1 for methane vapor reforming. The first methane reaction gas contained CH4 at a flow rate of 5 ml / min and water vapor at a flow rate of 25 ml / min. An inert gas, including one of nitrogen, argon, or helium, was introduced into the quartz glass tube at a flow rate of 20 ml / min. The test was conducted at 700-1000°C.
[0049] The gas inside and outside the four-channel tubular dense membrane N1 was introduced into a GC (gas chromatograph) to detect the gas conversion efficiency. The results showed that at 1000℃, the conversion rate of methane water vapor reforming was 70.4%; the purity of the recovered hydrogen was 99.2%; which was 25% higher than that of the blank group (the reaction gas was introduced into a catalyst-free quartz tube).
[0050] 4.2 Dry Reforming: Under identical conditions, the experiment was repeated for dry methane reforming by replacing the first methane reactant gas in the wet reforming process (4.1) with the second methane reactant gas. The second methane reactant gas had a CH4 flow rate of 5 ml / min and a CO2 flow rate of 25 ml / min. The experimental results showed that at 1000℃, the conversion rate of dry methane reforming was 80.1%; the purity of the recovered hydrogen was 99.1%; this was higher than the 32% conversion rate of the blank group (where the reactant gas was passed through a catalyst-free quartz tube). Example 5:
[0051] This embodiment describes a method for applying a tubular dense nickel film for methane reforming, specifically including: 5.1 Wet reforming: Methane water vapor reforming was performed using the same conditions as in 4.1 wet reforming, employing the four-channel tubular dense membrane N2 prepared in Example 2. Test results showed that at 1000°C, the conversion rate of methane water vapor reforming was 74.9%; the purity of the recovered hydrogen was 99.1%, which was 25% higher than the conversion rate of the blank group (where the reaction gas was passed through a catalyst-free quartz tube).
[0052] 5.2 Dry Reforming: Methane dry reforming was performed under the same conditions as in section 4.2 using a four-channel tubular dense membrane N2. Test results showed that at 1000℃, the conversion rate of methane dry reforming was 86.1%; the purity of the recovered hydrogen was 99.3%; and this was 32% higher than the conversion rate of the blank group (where the reaction gas was passed through a catalyst-free quartz tube). Example 6:
[0053] This embodiment describes a method for applying a tubular dense nickel film for methane reforming, specifically including: 6.1 Wet reforming: Methane water vapor reforming was performed using the four-channel tubular dense membrane N3 prepared in Example 3, under the same conditions as wet reforming in 4.1. Test results showed that the conversion rate of methane water vapor reforming was 80.3% at 1000°C; the purity of the recovered hydrogen was 99.1%; which was 25% higher than the conversion rate of the blank group (where the reaction gas was passed through a catalyst-free quartz tube).
[0054] 6.2 Dry Reforming: Methane dry reforming was performed under the same conditions as in section 4.2 using a four-channel tubular dense membrane N3. Test results showed that at 1000℃, the conversion rate of methane dry reforming was 89.2%; the purity of the recovered hydrogen was 99.5%; and this was 32% higher than the conversion rate of the blank group (where the reaction gas was passed through a catalyst-free quartz tube).
[0055] It will be understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for the production of a tubular compact metal nickel film for the reforming of methane, characterized in that, The application relates to a preparation method of a tubular dense metal nickel film for methane reforming. The poly-methyl methacrylate is dissolved in N-methyl-2-pyrrolidone, and the raw material is added under mechanical stirring at 50-100 DEG C, and then the stirring is continued to uniformly disperse the solution to obtain a film solution; The film solution is transferred to a multi-channel metal spinning head device to be extruded at room temperature to obtain a nickel film precursor; The nickel film precursor is sintered at high temperature in a hydrogen atmosphere to obtain a tubular dense film; The raw material is metal nickel powder or metal nickel oxide powder; The tubular dense film has a circular tube structure with multiple channels in the inside, and the circular tube structure has a supporting structure at the center position to thin the tube wall of the circular tube structure; The inner surface of the tubular dense film is formed with uniformly distributed nickel nanoparticles with a particle size of 100-500 nm in a hemispherical protrusion or crystal grain epitaxial structure.
2. The production method according to claim 1, characterized by, Further comprising: The number and size of the nickel nanoparticles are controlled by changing the type of the raw material, the temperature rising program and temperature of the high-temperature sintering.
3. The preparation method according to claim 1, characterized in that, The particle size of the metal nickel powder and the metal nickel oxide powder is 1-5 um.
4. The method of claim 1, wherein, The mass percentage of the raw material, the poly-methyl methacrylate and the N-methyl-2-pyrrolidone is (70-75 wt.%):(5-10 wt.%):(20-25 wt.%).
5. The preparation method according to claim 1, characterized in that, The tube wall of the circular tube structure is 50 um.
6. The method of claim 1, wherein, The high-temperature sintering of the nickel film precursor in a hydrogen atmosphere comprises: at a rate of 2-3 °C / min -1 from room temperature to 1200-1400 °C, and held for a period of time, and then cooled to room temperature at a rate of 3 °C / min -1 to complete sintering.
7. The preparation method according to claim 1, characterized in that, The hydrogen atmosphere adopts H2 and Ar mixed gas, and the H2 concentration is 5-99 mol%.
8. A tubular dense metal nickel film for methane reforming prepared by the preparation method in any one of claims 1-7.
9. A method of using the tubular compact metal nickel film for methane reforming according to claim 8, characterized by, Further comprising: The two ends of the tubular dense film are respectively connected with alumina corundum pipes, and then the pipes are loaded into a quartz glass pipe, one end of the corundum pipe is arranged to extend out of the quartz glass pipe and be connected with an external gas source to assemble a reactor; Methane reaction gas is introduced into the tubular dense film through the corundum pipe, and inert gas is introduced into the quartz glass pipe to carry out methane dry reforming or wet reforming reaction.
10. The use according to claim 9, characterized in that, The methane reaction gas is mixed gas of methane and water vapor or mixed gas of methane and carbon dioxide.