Apparatus for synthesizing methane and method for synthesizing methane

Abstract

Provided is an apparatus for synthesizing methane, the apparatus having: a reactor for housing a catalyst that contains a metal and an oxide; a first plasma source for generating plasma from CO2 gas; and a second plasma source for generating plasma from H2 gas. A first plasma generated by the first plasma source and a second plasma generated by the second plasma source come into contact with the catalyst in the reactor to produce methane.

Description

Apparatus for synthesizing methane and method for synthesizing methane

[0001] The present invention relates to an apparatus for synthesizing methane and a method for synthesizing methane.

[0002] Recent CO ２ In response to the growing need to reduce CO ２ Technologies for converting gas into other valuable resources are attracting attention. For example, CO ２ When the gas is reacted with hydrogen, methane can be synthesized.

[0003] A thermal catalytic reaction process is known as a common technique for synthesizing methane (see, for example, Patent Document 1).

[0004] In the thermal catalytic reaction process, CO is generated in a reactor heated to a high temperature. ２ Gas and H ２ A mixture of gases is supplied, and when the mixture comes into contact with a catalyst, methane can be synthesized.

[0005] JP 2012-140382 A

[0006] In conventional thermal catalytic reaction processes, the reactor needs to be heated to a high temperature to promote the reaction. However, in such a high-temperature environment, the catalyst is prone to deterioration. In addition, in order to create such a high-temperature environment, electricity is required to supply power to a heater, etc., which is a new CO ２ This can cause gas generation.

[0007] The present invention has been made in view of the above background, and an object of the present invention is to provide an apparatus and method that can synthesize methane more efficiently without requiring high-temperature treatment as in the conventional methods.

[0008] The present invention provides an apparatus for synthesizing methane, comprising: a reactor containing a catalyst including a metal and an oxide; ２ a first plasma source for generating plasma from a gas; ２and a second plasma source for generating plasma from a gas, wherein a first plasma generated by the first plasma source and a second plasma generated by the second plasma source contact the catalyst in the reactor, thereby producing methane.

[0009] The present invention also provides a method for synthesizing methane, comprising: disposing a catalyst containing a metal and an oxide in a reactor; and generating CO by a first plasma source. ２ The gas is converted into plasma to generate a first plasma, and H is generated by a second plasma source. ２ A method is provided for producing methane by forming a gas into a plasma, generating a second plasma, and contacting the first plasma and the second plasma with the catalyst.

[0010] The present invention can provide an apparatus and method that can synthesize methane more efficiently without requiring high-temperature treatment as in the prior art.

[0011] 1 is a diagram schematically illustrating an example of a cross section of an apparatus for synthesizing methane according to one embodiment of the present invention. 2 is a diagram schematically illustrating a first plasma source included in the apparatus for synthesizing methane according to one embodiment of the present invention. 3 is a diagram schematically illustrating a flow of an example of a method for synthesizing methane according to one embodiment of the present invention. 4 is a graph showing the relationship between SEI and yield Tm.

[0012] An embodiment of the present invention will be described below.

[0013] As mentioned above, in conventional thermal catalytic reaction processes, the inside of the reactor must be heated to a high temperature to promote the reaction.

[0014] However, in such a high-temperature environment, the catalyst is likely to deteriorate. In addition, in order to create such a high-temperature environment, electricity is required to supply power to a heater, etc., which is a new CO ２ This can cause gas generation.

[0015] To address this issue, it may be possible to apply a plasma reaction process to the methane synthesis reaction.

[0016] In the plasma reaction process, CO ２ Gas and H ２ A mixture of gases is converted into various highly reactive plasmas, which react in the presence of a catalyst to produce methane. The plasma reaction process reduces the activation energy required for methane synthesis. This eliminates the need for high-temperature heating, as in the thermal catalytic reaction process, potentially reducing the energy input required for the reaction.

[0017] However, the inventors of the present invention have found that in a typical plasma reaction process, it is not easy to increase the methane yield with low input energy.

[0018] Here, the methane yield Tm is expressed by the following formula (1): Tm = methane generation amount (m ３ ) / CO ２ Input amount (m ３ ) (1) In the conventional plasma reaction process, the reason for the low methane yield Tm is CO ２ Gas and H ２ This is thought to be because the optimal plasma conditions for the reaction differ depending on the gas. In other words, when a mixed gas is plasmatized under a single condition, the optimal plasma for synthesis cannot be obtained, making it difficult to synthesize methane efficiently.

[0019] Based on this consideration, the inventors of the present invention ２ Gas and H ２ The inventors discovered that by converting each gas into plasma separately, it is possible to generate plasma species that are optimal for the reaction, and as a result, more efficient methane synthesis becomes possible, leading to the present invention.

[0020] That is, the present invention provides an apparatus for synthesizing methane, comprising: a reactor containing a catalyst including a metal and an oxide; ２ a first plasma source for generating plasma from a gas; ２and a second plasma source for generating plasma from a gas, wherein a first plasma generated by the first plasma source and a second plasma generated by the second plasma source contact the catalyst in the reactor, thereby producing methane.

[0021] In one embodiment of the present invention, the above-mentioned thermal catalytic reaction process is not used, so high-temperature heat treatment is not essential for methane synthesis. Therefore, new CO ２ This significantly avoids the problem of gas generation, and also significantly suppresses the thermal degradation of the catalyst.

[0022] In addition, in one embodiment of the present invention, two plasma sources, namely CO ２ a first plasma source for generating plasma from a gas; ２ A second plasma source is used to convert the gas into a plasma.

[0023] In this case, the first plasma and the second plasma that are optimal for the reaction can be generated from the first plasma source and the second plasma source, respectively.

[0024] Therefore, in one embodiment of the present invention, methane can be synthesized more efficiently.

[0025] (Apparatus According to an Embodiment of the Present Invention) Hereinafter, an apparatus for synthesizing methane according to an embodiment of the present invention will be described in more detail with reference to the drawings.

[0026] FIG. 1 is a schematic diagram showing an example of a cross section of an apparatus for synthesizing methane according to one embodiment of the present invention.

[0027] As shown in FIG. 1, an apparatus 100 for synthesizing methane according to one embodiment of the present invention (hereinafter referred to as a “first apparatus”) includes a reactor 110, a first plasma source 140A, and a second plasma source 140B.

[0028] The reactor 110 has a reaction space 112 and an outlet 114. The reaction space 112 of the reactor 110 houses a container 120, which is filled with a catalyst 130. In the catalyst region of the reaction space 112, methane is synthesized by a plasma reaction, which will be described later.

[0029] The first plasma source 140A is a CO ２ It has the role of turning gas into plasma.

[0030] The first plasma source 140A has a first gas inlet 142A (not shown) and a first plasma outlet 144A. The first gas inlet 142A of the first plasma source 140A is for supplying CO ２ The first plasma outlet 144A of the first plasma source 140A is connected to a supply means (not shown) of the containing gas. The first plasma outlet 144A of the first plasma source 140A is in communication with the reaction space 112 of the reactor 110.

[0031] The second plasma source 140B is H ２ It has the role of turning gas into plasma.

[0032] The second plasma source 140B has a second gas inlet 142B (not shown) and a second plasma outlet 144B. The second gas inlet 142B of the second plasma source 140B is for supplying H ２ The second plasma outlet 144B of the second plasma source 140B is connected to a supply means (not shown) of the containing gas. The second plasma outlet 144B of the second plasma source 140B is in communication with the reaction space 112 of the reactor 110.

[0033] As shown in FIG. 1, the first apparatus 100 may further include a stirring mechanism 185 and a cooling mechanism 190 .

[0034] The stirring mechanism 185 has a function of stirring the catalyst 130 .

[0035] During methane synthesis, if the first plasma and the second plasma are continuously applied to the same location on the catalyst 130, the catalyst 130 may be locally heated, which may accelerate deterioration of the catalyst 130. By stirring the catalyst 130 with the stirring mechanism 185 during methane synthesis, it is possible to suppress such deterioration of the catalyst 130.

[0036] The cooling mechanism 190 has the function of cooling the container 120 and further the catalyst 130 .

[0037] By providing the cooling mechanism 190, it is possible to suppress the temperature rise of the catalyst 130 during the methane synthesis reaction.

[0038] The stirring mechanism 185 and the cooling mechanism 190 may be provided as needed and are not necessarily required.

[0039] When methane is synthesized by the first apparatus 100, CO 2 is introduced from the first gas inlet 142A of the first plasma source 140A. ２ The containing gas is supplied. ２ CO contained in the gas ２ The gas is turned into a plasma by the first plasma source 140A, resulting in the generation of vibrationally excited CO ２ , CO, and / or O. The generated first plasma is emitted from the first plasma outlet 144A to the catalyst 130 contained in the reaction space 112.

[0040] Similarly, H is introduced from the second gas inlet 142B of the second plasma source 140B. ２ The containing gas is supplied. ２ H contained in the containing gas ２ The gas is converted into plasma by the second plasma source 140B, generating activated species such as H radicals (hereinafter referred to as "second plasma"), which is emitted from the second plasma outlet 144B to the catalyst 130 contained in the reaction space 112.

[0041] Methane is produced on the catalyst 130 by a reaction between the first plasma and the second plasma. The overall reaction is, for example, as shown in the following formula (2): ２ +4H ２ →CH ４ +2H ２ O (2) is expressed as follows.

[0042] The methane produced is a by-product, as well as unreacted CO ２ Gas and H２ The by-products are released together with gases from an outlet 114 provided in the reactor 110. ２ In addition to O, CO gas and O ２ Gas is one example.

[0043] When the first device 100 is used, a thermal catalytic reaction process is not used in the reaction, so methane can be synthesized without high-temperature heating. ２ This significantly avoids the problem of gas generation, and also significantly suppresses the thermal degradation of the catalyst.

[0044] In addition, the first device 100 uses a first plasma source 140A and a second plasma source 140B. ２ Gas and H ２ The gases can be converted into plasma under separate conditions, resulting in the generation of first and second plasmas that are optimal for methane production, enabling more efficient methane synthesis.

[0045] (Details of the Apparatus According to an Embodiment of the Present Invention) Next, each component included in the apparatus according to an embodiment of the present invention will be described in more detail. Note that, here, the apparatus according to an embodiment of the present invention is assumed to be the first apparatus 100 described above. Therefore, the reference numerals shown in FIG. 1 will be used to represent each component.

[0046] (Container 120 and Catalyst 130) The container 120 is filled with the catalyst 130.

[0047] The vessel 120 is preferably constructed of an inorganic dielectric material such as quartz, as a metallic vessel may adversely affect plasma state transitions, such as high temperature arc plasma and plasma extinction.

[0048] The catalyst 130 includes a metal and an oxide.

[0049] Examples of metals include, but are not limited to, Ru, Au, Pd, Pt, Cd, Ni, and Fe. Multiple metals may also be used.

[0050] On the other hand, oxides include, but are not limited to, titanium oxide, aluminum oxide, zinc oxide, tin oxide, etc. Multiple oxides may be used.

[0051] The catalyst may be in the form of particles, tablets or pellets.

[0052] Hereinafter, the state of the catalyst 130 filled in the container 120 will also be referred to as a "catalyst layer" or a "layered catalyst." The outermost surface of the "catalyst layer" will be referred to as an "upper surface 132" (see FIG. 1).

[0053] (First Plasma Source 140A and Second Plasma Source 140B) The first plasma source 140A generates a plasma from the supplied CO ２ The configuration is not particularly limited as long as the first plasma can be generated appropriately from the contained gas.

[0054] FIG. 2 is a cross-sectional view schematically showing an example of the configuration of the first plasma source 140A.

[0055] In the example shown in FIG. 2, the first plasma source 140A includes a dielectric tube 152A, a first electrode 162A, and a second electrode 164A.

[0056] The dielectric tube 152A has an inlet (not shown), an outlet 144A (which also serves as the first plasma outlet of the first plasma source 140A), and an internal space 156A defined therebetween. The dielectric tube 152A is made of, for example, but not limited to, quartz.

[0057] The first electrode 162A has a generally rod-like shape and is inserted into the internal space 156A of the dielectric tube 152A.

[0058] On the other hand, the second electrode 164A is wound around the outer periphery of the dielectric tube 152A. The second electrode 164A may have the form of, for example, a mesh.

[0059] In the first plasma source 140A having such a configuration, a dielectric barrier discharge can be generated by applying an alternating voltage between the first electrode 162A and the second electrode 164A. ２The gas can be formed into a plasma and a first plasma can be emitted from outlet 144A.

[0060] The second plasma source 140B may have a similar configuration, for example, the second plasma source 140B may have a dielectric tube, a first electrode, and a second electrode, and the dielectric tube may have an inlet and an outlet (which may also be the second plasma outlet 144B of the second plasma source 140B) and an interior space defined therebetween.

[0061] In the first apparatus 100, the first plasma source 140A and the second plasma source 140B are preferably arranged to satisfy the following positional relationship: - The intersection of the extension line of the extension axis of the dielectric tube 152A in the first plasma source 140A beyond the first plasma outlet 144A and the extension line of the extension axis of the dielectric tube in the second plasma source 140B beyond the second plasma outlet 144B intersects at the upper surface 132 of the catalyst 130 or intersects within the layer of the catalyst 130.

[0062] As in conventional plasma reaction processes, CO ２ Gas and H ２ When a mixture of gases is used, CO is released before the methane formation reaction occurs on the catalyst surface. ２ Gas and H ２ Another gas phase reaction may occur between the gases, which may reduce the amount of plasma activated species required for methane synthesis, resulting in a decrease in the methane yield Tm.

[0063] In contrast, when the first plasma source 140A and the second plasma source 140B are arranged as described above, it is possible to more reliably bring the first plasma generated by the first plasma source 140A and the second plasma generated by the second plasma source 140B into contact with the catalyst 130. As a result, it is possible to further increase the yield Tm of methane synthesis.

[0064] (Stirring Mechanism 185 and Cooling Mechanism 190) The stirring mechanism 185 may have any configuration as long as it can suitably stir the catalyst 130.

[0065] Similarly, the cooling mechanism 190 may have any configuration as long as it can suitably cool the container 120 and the catalyst 130. For example, the cooling mechanism 190 may be a water-cooled type and may have a configuration in which water is circulated through a thermally conductive conduit.

[0066] The temperature of the catalyst 130 is preferably maintained below 150° C. by the stirring mechanism 185 and / or the cooling mechanism 190 .

[0067] (Other Features of the First Apparatus 100) In conventional plasma reaction processes, it is necessary to reduce the pressure inside the reactor. To perform such a vacuum treatment, a pump must be operated, which requires the use of new CO ２ It can be a cause of occurrence.

[0068] In contrast, in the first apparatus 100, it is not necessary to reduce the pressure in the reaction space 112 during methane synthesis. For example, methane synthesis may be performed under atmospheric pressure. Therefore, in the first apparatus 100, methane can be synthesized with significantly lower power than in conventional plasma reaction processes.

[0069] Furthermore, in the first apparatus 100, when the specific input energy SEI is expressed by the following equation (3), SEI (kJ / mol) = total input energy P (kJ / sec) input to the reaction system / total flow rate F (mol / sec) of reaction gas supplied to the reaction system Equation (3) The specific input energy SEI when the methane yield Tm expressed by the above equation (1) is 70% may be 200 kJ / mol or less.

[0070] In equation (3), the input energy P includes the energy administered to the first plasma source 140A and the second plasma source 140B, as well as the energy supplied to auxiliary equipment involved in the reaction, such as a heater. The total flow rate F of the reactant gas includes the flow rate of the gas supplied to each of the first plasma source 140A and the second plasma source 140B.

[0071] The specific energy input SEI can be used as an index of the applied power used in methane synthesis, and it can be said that the smaller the value of the specific energy input SEI, the less energy is required for methane synthesis.

[0072] In the first unit 100, the total specific input energy SEI when the methane yield Tm is 70% is preferably 190 kJ / mol or less, and more preferably 185 kJ / mol or less.

[0073] As will be described later in the experiment, in a thermal catalytic reaction process, the specific input energy (SEI) required to achieve a methane yield (Tm) of 70% is approximately 600 kJ / mol. From the comparison of SEI, it can be said that in one embodiment of the present invention, the energy required for the reaction can be reduced to approximately one-third of that required in a conventional thermal catalytic reaction process.

[0074] (Method for synthesizing methane according to one embodiment of the present invention) Next, with reference to FIG. 3, an example of a method for synthesizing methane according to one embodiment of the present invention will be described.

[0075] FIG. 3 is a schematic diagram showing a flow of an example of a method for synthesizing methane according to one embodiment of the present invention.

[0076] As shown in FIG. 3 , the method for synthesizing methane according to one embodiment of the present invention (hereinafter referred to as the “first method”) includes the steps of: (1) placing a catalyst containing a metal and an oxide in a reactor (step S110); and (2) generating CO by a first plasma source. ２ The gas is converted into plasma to generate a first plasma, and H is generated by a second plasma source. ２ (3) generating methane by bringing the first plasma and the second plasma into contact with the catalyst (step S130).

[0077] Each step will be described below. For clarity, each step will be described using the first method performed using the first apparatus 100 described above as an example. Therefore, the reference numerals used hereinafter correspond to the components shown in Figures 1 and 2. However, it will be apparent to those skilled in the art that the first method may also be performed using another apparatus.

[0078] (Step S110) First, the catalyst 130 containing a metal and an oxide is placed in the reactor 110.

[0079] The catalyst 130 is contained in a container 120. The container 120 is preferably made of a dielectric material such as quartz.

[0080] The catalyst may be in the form of particles, tablets or pellets.

[0081] The catalyst 130 includes a metal and an oxide. Examples of metals include, but are not limited to, Ru, Au, Pd, Pt, Cd, Ni, and Fe. Multiple metals may be used. Examples of oxides include, but are not limited to, titanium oxide, aluminum oxide, zinc oxide, and tin oxide. Multiple oxides may be used.

[0082] (Step S120) Next, CO is introduced from the first gas inlet 142A of the first plasma source 140A. ２ A containing gas is provided.

[0083] CO ２ The contained gas is CO ２ The gas may be supplied alone or as a mixture of gases. ２ The gas may include a gas and a noble gas (such as argon and / or helium, for example).

[0084] CO contained in the mixed gas ２ The concentration of the gas may be, for example, in the range of 10% to 90% (volume ratio).

[0085] Next, an alternating voltage is applied between the first electrode 162A and the second electrode 164A provided in the first plasma source 140A. ２ CO contained in the gas ２ The gas is converted into plasma to generate a first plasma, which is emitted toward the catalyst 130 from the first plasma outlet 144A of the first plasma source 140A.

[0086] Similarly, H is introduced from the second gas inlet 142B of the second plasma source 140B.２ A containing gas is provided.

[0087] H ２ The contained gas is H ２ The gas may be supplied alone or as a mixed gas. ２ The gas may include a gas and a noble gas (such as argon and / or helium, for example).

[0088] H contained in the mixed gas ２ The concentration of the gas may be, for example, in the range of 10% to 90% (volume ratio).

[0089] Next, an alternating voltage is applied between the first electrode and the second electrode provided in the second plasma source 140B. ２ H contained in the containing gas ２ The gas is converted into plasma to generate a second plasma, which is emitted toward the catalyst 130 from the second plasma outlet 144B of the second plasma source 140B.

[0090] (Step S130) Next, the first plasma and the second plasma come into contact with the catalyst 130, causing the reaction represented by the above formula (2) to proceed, producing methane.

[0091] The methane produced is a by-product, as well as unreacted CO ２ Gas and H ２ The by-products are released together with gases from an outlet 114 provided in the reactor 110. ２ In addition to O, CO gas and O ２ CO gas and O ２ Gas is a product that is not produced in conventional pyrolysis processes.

[0092] Here, as mentioned above, the first plasma and the second plasma are preferably emitted such that: the intersection of the central elongation axis of the first plasma and the central elongation axis of the second plasma intersects at the upper surface 132 of the catalyst 130 or intersects within the layer of the catalyst 130.

[0093] By adopting such an embodiment, it becomes possible to more efficiently bring the first plasma and the second plasma into contact with the catalyst 130, and as a result, it is possible to further increase the yield Tm of methane synthesis.

[0094] It should be noted that the reaction space 112 of the reactor 110 does not necessarily need to be depressurized during methane synthesis, i.e., methane synthesis may be carried out under atmospheric pressure, which significantly reduces the input energy for the reaction.

[0095] During the methane synthesis, the catalyst 130 may be stirred as needed. Alternatively or additionally, the catalyst 130 may be cooled. A stirring mechanism 185 may be used to stir the catalyst 130. A cooling mechanism 190 may be used to cool the catalyst 130.

[0096] By utilizing these mechanisms, the thermal degradation of the catalyst can be significantly suppressed.

[0097] Through the above steps, methane can be synthesized.

[0098] Examples of the present invention will be described below. In the following description, Examples 1 to 4 are examples, and Examples 11 to 14 are comparative examples.

[0099] Example 1 A methane synthesis test was carried out using the first apparatus and the first method.

[0100] A quartz tube with an outer diameter of 30 mm, an inner diameter of 26 mm, and a length of 120 mm was used as the reactor. A quartz boat with a length of 70 mm and a width of 15 mm was used as the container for containing the catalyst, and the container filled with the catalyst was placed inside the reactor.

[0101] The catalyst used was a ruthenium / titanium oxide catalyst (2:98 (weight ratio)) (manufactured by N.E. Chemcat Corporation). The amount of catalyst was 10 g.

[0102] The dielectric tube of the first plasma source (a quartz tube with a thickness of 1 mm) contained CO ２ and argon mixed gas (CO ２ :Ar = 20:100 (volume ratio)) ３The second plasma source was provided with a dielectric tube (a quartz tube with a thickness of 0.5 mm) at a rate of 1 / min. ２ and argon mixed gas (H ２ :Ar = 80:100 (volume ratio)) ３ / min.

[0103] An alternating power (peak-to-peak voltage 15 kV) was applied to the first plasma source to generate a first plasma, and an alternating power (peak-to-peak voltage 14 kV) was applied to the second plasma source to generate a second plasma.

[0104] The first plasma and the second plasma were irradiated onto the catalyst for 10 minutes, and the first plasma and the second plasma were irradiated onto the catalyst so that the extensions of the respective dielectric tubes intersected on the upper surface of the catalyst.

[0105] During the reaction, the catalyst was not heated by an external heater, but a thermocouple was installed at the bottom of the catalyst layer placed in the vessel to measure the temperature of the catalyst during methane synthesis.

[0106] (Examples 2 to 4) In the same manner as in Example 1, a methane synthesis test was carried out.

[0107] However, in Examples 2 to 4, the conditions such as the voltage, current, and power applied to the first plasma source and the second plasma source were changed from those in Example 1.

[0108] Example 11 A methane synthesis test was carried out in a reactor by the following method (thermal catalytic reaction process).

[0109] The reactor used was a quartz tube with an outer diameter of 30 mm, an inner diameter of 26 mm, and a length of 400 mm. A quartz boat packed with the catalyst described above was placed inside the reactor. The dimensions of the quartz boat were a total length of 70 mm and a width of approximately 15 mm. The amount of catalyst was 10 g.

[0110] During the experiment, the entire reactor was heated to 200° C. using a heater.

[0111] Methane synthesis was carried out by supplying reaction gas into a reactor heated to 200°C.２ , CO ２ , and a mixed gas of Ar (H ２ :CO ２ :Ar=80:20:200 (volume ratio)) was used, and this was added to 300 cm ３ The mixture was fed into the reactor at a flow rate of 1 / min.

[0112] The reaction time was 10 minutes.

[0113] (Examples 12 to 14) In the same manner as in Example 11, a methane synthesis test was carried out.

[0114] However, in Examples 12 to 14, the catalyst heating temperature was changed from that in Example 11.

[0115] Table 1 below shows the test conditions for each example.

[0116] (Results and Discussion) In each example, the methane yield (Tm) was calculated from the amount of methane produced using the above-mentioned formula (1). In addition, the specific energy input (SEI) was calculated from the total amount of electricity supplied to the reaction system using the above-mentioned formula (3).

[0117] The results obtained are summarized in Table 1 above.

[0118] In Examples 1 to 4, the catalyst was not heated, but a yield Tm of more than 50% was obtained in all cases.

[0119] FIG. 4 shows the relationship between SEI and yield Tm.

[0120] 4, it was found that the specific energy input SEI was relatively large in Examples 11 to 14, which employed a thermal catalytic reaction process, while the specific energy input SEI was relatively small in Examples 1 to 4, which correspond to one embodiment of the present invention.

[0121] For example, when the methane yield Tm was 70%, the specific energy input SEI was approximately 600 kJ / mol in the case of the thermal catalytic reaction process, whereas the specific energy input SEI in the method according to one embodiment of the present invention was approximately 150 kJ / mol.

[0122] As described above, it was found that the method according to one embodiment of the present invention reduces the specific energy input SEI to about one-third of that of the method employing a thermal catalytic reaction process.

[0123] From the above results, it was confirmed that in one embodiment of the present invention, a good methane yield Tm can be obtained even with a relatively small specific input energy SEI.

[0124] (Aspects of the Invention) The present invention may have the following aspects.

[0125] (Aspect 1) A device for synthesizing methane, comprising: a reactor containing a catalyst including a metal and an oxide; ２ a first plasma source for generating plasma from a gas; ２ and a second plasma source for generating plasma from a gas, wherein the first plasma generated by the first plasma source and the second plasma generated by the second plasma source contact the catalyst in the reactor, thereby producing methane.

[0126] (Aspect 2) The first plasma source has CO ２ The second plasma source has a first dielectric tube through which a containing gas flows, a first electrode inserted into the first dielectric tube, and a second electrode disposed on the outer periphery of the first dielectric tube, and / or ２ The apparatus of claim 1, further comprising: a second dielectric tube through which the containing gas flows; a third electrode inserted into the second dielectric tube; and a fourth electrode disposed on the outer periphery of the second dielectric tube.

[0127] (Aspect 3) The device according to aspect 2, wherein a dielectric barrier discharge is generated between the first electrode and the second electrode, and / or a dielectric barrier discharge is generated between the third electrode and the fourth electrode.

[0128] (Aspect 4) The device described in Aspect 2 or 3, wherein the catalyst is arranged in layers, the first dielectric tube has a first outlet for the first plasma, the second dielectric tube has a second outlet for the second plasma, and an intersection of an extension line of the extension axis of the first dielectric tube beyond the first outlet and an extension line of the extension axis of the second dielectric tube beyond the second outlet intersects on the upper surface of the catalyst layer or intersects within the catalyst layer.

[0129] (Aspect 5) The device according to any one of Aspects 1 to 4, wherein the catalyst is filled in a container, and the container is made of an inorganic dielectric.

[0130] (Aspect 6) The yield Tm of methane production is expressed by the following formula (1), Tm = CH ４ Production amount (m ３ ) / CO ２ Input amount (m ３ ) Equation (1) When the specific input energy SEI is the following equation (2), SEI (kJ / mol) = total input energy P (kJ / sec) input to reaction system / total flow rate F (mol / sec) of reaction gas supplied to reaction system Equation (2) The apparatus according to any one of aspects 1 to 5, wherein the specific input energy SEI when the yield is 70% is 200 kJ / mol or less.

[0131] (Aspect 7) The apparatus according to any one of Aspects 1 to 6, further comprising: a cooling mechanism for cooling the catalyst; and / or a stirring mechanism for stirring the catalyst.

[0132] (Aspect 8) The apparatus of any one of aspects 1 to 7, wherein the temperature of the catalyst is maintained below 150°C.

[0133] (Aspect 9) H as a by-product ２ In addition to O, CO and O ２ 9. The apparatus of any one of aspects 1 to 8, wherein at least one of

[0134] (Aspect 10) The device according to any one of Aspects 1 to 9, wherein the catalyst includes at least one of Ru, Au, Pd, Pt, Cd, Ni, and Fe as the metal, and at least one of titanium oxide, aluminum oxide, zinc oxide, and tin oxide as the oxide.

[0135] (Aspect 11) The apparatus according to any one of Aspects 1 to 10, wherein the inside of the reactor is an atmospheric pressure environment.

[0136] (Embodiment 12) A method for synthesizing methane, comprising: disposing a catalyst containing a metal and an oxide in a reactor; and generating CO by a first plasma source. ２ The gas is converted into plasma to generate a first plasma, and H is generated by a second plasma source. ２ A method for producing methane by converting a gas into a plasma and generating a second plasma; and contacting the first plasma and the second plasma with the catalyst.

[0137] (Aspect 13) The first plasma source has a CO ２ The second plasma source has a first dielectric tube through which a containing gas flows, a first electrode inserted into the first dielectric tube, and a second electrode disposed on the outer periphery of the first dielectric tube, and / or ２ A method according to aspect 12, comprising: a second dielectric tube through which the containing gas flows; a third electrode inserted into the second dielectric tube; and a fourth electrode disposed on the outer periphery of the second dielectric tube.

[0138] (Aspect 14) The CO ２ The contained gas is CO ２ 14. The method of embodiment 13, comprising a gas and a noble gas.

[0139] (Aspect 15) The H ２ The contained gas is H ２ 15. The method of aspect 13 or 14, comprising a gas and a noble gas.

[0140] (Aspect 16) The method described in aspect 13, wherein the catalyst is arranged in a layer, the first dielectric tube has a first outlet for the first plasma, the second dielectric tube has a second outlet for the second plasma, and an intersection of an extension line of the extension axis of the first dielectric tube beyond the first outlet and an extension line of the extension axis of the second dielectric tube beyond the second outlet intersects on the upper surface of the catalyst layer or intersects within the catalyst layer.

[0141] (Aspect 17) The yield Tm of methane production is expressed by the following formula (1), Tm = CH ４ Production amount (m ３ ) / CO ２ Input amount (m ３ ) Formula (1) When the specific input energy SEI is expressed by the following formula (2), SEI (kJ / mol) = total input energy P (kJ / sec) input to reaction system / total flow rate F (mol / sec) of reaction gas supplied to reaction system Formula (2) The method according to any one of aspects 12 to 16, wherein the specific input energy SEI when the yield is 70% is 200 kJ / mol or less.

[0142] (Aspect 18) The method of any one of aspects 12 to 17, wherein the catalyst is agitated while the first plasma and the second plasma are contacted with the catalyst.

[0143] (Aspect 19) The method of any one of aspects 12 to 18, wherein the catalyst temperature is maintained below 150°C during the production of methane.

[0144] (Aspect 20) When producing methane, H is produced as a by-product. ２ In addition to O, CO and O ２ 20. The method of any one of aspects 12 to 19, wherein at least one of

[0145] (Aspect 21) The method according to any one of Aspects 12 to 20, wherein the catalyst includes, as the metal, at least one of Ru, Au, Pd, Pt, Cd, Ni, and Fe, and as the oxide, at least one of titanium oxide, aluminum oxide, zinc oxide, and tin oxide.

[0146] (Aspect 22) The method of any one of aspects 12 to 21, wherein the methane production is carried out under atmospheric pressure.

[0147] This application claims priority based on Japanese Patent Application No. 2023-189743, filed on November 7, 2023, the entire contents of which are incorporated herein by reference.

[0148] 100 First device 110 Reactor 112 Reaction space 114 Outlet 120 Container 130 Catalyst 132 Upper surface 140A First plasma source 140B Second plasma source 142A First gas inlet 142B Second gas inlet 144A First plasma outlet (outlet of dielectric tube) 144B Second plasma outlet 152A Dielectric tube 156A Internal space 162A First electrode 164A Second electrode 185 Stirring mechanism 190 Cooling mechanism

Claims

1. An apparatus for synthesizing methane, comprising: a reactor containing a catalyst including a metal and an oxide; ２ a first plasma source for generating plasma from a gas; ２ and a separate second plasma source for generating plasma from a gas, wherein a first plasma generated by the first plasma source and a second plasma generated by the second plasma source contact the catalyst in the reactor to generate methane.

2. The first plasma source has a CO ２ The plasma source has a first dielectric tube through which a gas containing gas flows, a first electrode inserted into the first dielectric tube, and a second electrode disposed on the outer periphery of the first dielectric tube, and / or the second plasma source has a H ２ 2. The apparatus of claim 1, further comprising: a second dielectric tube through which the containing gas flows; a third electrode inserted into the second dielectric tube; and a fourth electrode disposed around the outer periphery of the second dielectric tube.

3. The device according to claim 2, wherein a dielectric barrier discharge is generated between the first electrode and the second electrode, and / or a dielectric barrier discharge is generated between the third electrode and the fourth electrode.

4. The apparatus of claim 2, wherein the catalyst is arranged in layers, the first dielectric tube has a first outlet for the first plasma, and the second dielectric tube has a second outlet for the second plasma, and an intersection of an extension of the axis of extension of the first dielectric tube beyond the first outlet and an extension of the axis of extension of the second dielectric tube beyond the second outlet intersects at an upper surface of the layer of catalyst or intersects within the layer of catalyst.

5. The apparatus according to claim 1, wherein the catalyst is filled in a container, and the container is made of an inorganic dielectric material.

6. The yield of methane production, Tm, is expressed as the following formula (1): Tm = CH ４ Production amount (m ３ ) / CO ２ Input amount (m ３ ) Formula (1) When the specific input energy SEI is the following formula (2), SEI (kJ / mol) = total input energy P (kJ / sec) input to reaction system / total flow rate F (mol / sec) of reactant gas supplied to reaction system Formula (2) The apparatus described in claim 1, wherein the specific input energy SEI when the yield is 70% is 200 kJ / mol or less.

7. The apparatus according to claim 1, further comprising: a cooling mechanism for cooling the catalyst; and / or a stirring mechanism for stirring the catalyst.

8. The apparatus of claim 1, wherein the temperature of the catalyst is maintained below 150°C.

9. As a by-product, H ２ In addition to O, CO and O ２ The apparatus of claim 1 , wherein at least one of 10. The apparatus of claim 1, wherein the catalyst includes at least one of Ru, Au, Pd, Pt, Cd, Ni, and Fe as the metal, and at least one of titanium oxide, aluminum oxide, zinc oxide, and tin oxide as the oxide.

11. The apparatus according to claim 1, wherein the inside of the reactor is an atmospheric pressure environment.

12. A method for synthesizing methane, comprising: disposing a catalyst containing a metal and an oxide in a reactor; and generating CO by a first plasma source. ２ The gas is turned into plasma to generate a first plasma, and H is generated by a second plasma source. ２ A method for producing methane by forming a gas into a plasma and generating a second plasma; and contacting the first plasma and the second plasma with the catalyst.

13. The first plasma source has a CO ２ The plasma source has a first dielectric tube through which a gas containing gas flows, a first electrode inserted into the first dielectric tube, and a second electrode disposed on the outer periphery of the first dielectric tube, and / or the second plasma source has a H ２ 13. The method of claim 12, further comprising: a second dielectric tube through which the containing gas flows; a third electrode inserted into the second dielectric tube; and a fourth electrode disposed on an outer periphery of the second dielectric tube.

14. The above CO ２ The gas contained is CO ２ The method of claim 13 comprising a gas and a noble gas.

15. The above H ２ The gas contained is H ２ The method of claim 13 comprising a gas and a noble gas.

16. The method of claim 13, wherein the catalyst is arranged in a layer, the first dielectric tube has a first outlet for the first plasma, and the second dielectric tube has a second outlet for the second plasma, and an intersection of an extension of the axis of extension of the first dielectric tube beyond the first outlet and an extension of the axis of extension of the second dielectric tube beyond the second outlet intersects at an upper surface of the layer of catalyst or intersects within the layer of catalyst.

17. The yield of methane production, Tm, is expressed as the following formula (1): Tm = CH ４ Production amount (m ３ ) / CO ２ Input amount (m ３ ) Formula (1) When the specific input energy SEI is the following formula (2), SEI (kJ / mol) = total input energy P (kJ / sec) input to reaction system / total flow rate F (mol / sec) of reactant gas supplied to reaction system Formula (2) The method according to claim 12, wherein the specific input energy SEI when the yield is 70% is 200 kJ / mol or less.

18. The method of claim 12, wherein the catalyst is agitated while contacting the first plasma and the second plasma with the catalyst.

19. The method of claim 12, wherein the catalyst temperature is maintained below 150° C. during the production of methane.

20. When producing the methane, H is produced as a by-product. ２ In addition to O, CO and O ２ The method of claim 12 , wherein at least one of 21. The method of claim 12, wherein the catalyst comprises at least one of Ru, Au, Pd, Pt, Cd, Ni and Fe as the metal, and at least one of titanium oxide, aluminum oxide, zinc oxide and tin oxide as the oxide.

22. The method of claim 12, wherein the production of methane is carried out at atmospheric pressure.