Reactor

Abstract

Provided is a reactor used for a process involving two or more elementary reactions, namely an exothermic reaction and an endothermic reaction, the reactor having excellent reaction efficiency and reduced catalyst degradation. A reactor according to an embodiment of the present invention is used in a process involving two or more elementary reactions, namely an exothermic reaction and an endothermic reaction. The reactor comprises: a gas channel into which a feedstock gas containing a first component and a second component is supplied; and a catalyst-containing part disposed so as to be capable of contacting the feedstock gas supplied to the gas channel. The catalyst-containing part includes an endothermic reaction promoting catalyst capable of promoting an endothermic reaction related to the first component and an exothermic reaction promoting catalyst capable of promoting an exothermic reaction between the reaction product of the first component and the second component. The dispersion ratio of the exothermic reaction promoting catalyst calculated in a cross-sectional analysis of the catalyst-containing part is 0.60 or more.

Description

reactor

[0001] The present invention relates to a reactor.

[0002] In recent years, efforts to reduce environmental impact have been made to recover carbon dioxide and reuse it as a raw material for carbon compounds. For example, methanation, in which carbon dioxide is converted to methane by reacting it with hydrogen, has been proposed (see, for example, Patent Document 1). A technology called ammonia methanation, which uses ammonia as a hydrogen source, has also been investigated. Ammonia methanation involves two reactions: an endothermic reaction in which ammonia is decomposed to produce hydrogen, and an exothermic reaction in which the resulting hydrogen is reacted with carbon dioxide to produce methane. For example, a hybrid catalyst, in which an ammonia decomposition catalyst and a methanation catalyst are physically mixed and molded into pellets, has been proposed for ammonia methanation (see, for example, Non-Patent Document 1). However, such hybrid catalysts often result in uneven dispersion of the ammonia decomposition catalyst and methanation catalyst in the pellets, which can result in localized heat generation due to the exothermic methanation reaction. As a result, problems such as insufficient methane yield and a tendency for catalyst degradation (sintering) to occur. These problems can occur not only in ammonia methanation but also in processes involving two or more elementary reactions, namely, exothermic and endothermic reactions.

[0003] As described above, there is a strong demand for a reactor that can be used in a process involving two or more elementary reactions, i.e., an exothermic reaction and an endothermic reaction, and that has excellent reaction efficiency and suppresses catalyst degradation.

[0004] Japanese Patent Application Laid-Open No. 2015-196619

[0005] JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 2023, VOL. 56, NO. 1, 2248176

[0006] A primary object of the present invention is to provide a reactor for use in a process including two or more elementary reactions, i.e., an exothermic reaction and an endothermic reaction, which has excellent reaction efficiency and suppresses catalyst deterioration.

[0007] [1] A reactor according to an embodiment of the present invention is used in a process including two or more elementary reactions, an exothermic reaction and an endothermic reaction. The reactor includes a gas flow path to which a feed gas containing a first component and a second component is supplied, and a catalyst-containing portion arranged to be in contact with the feed gas supplied to the gas flow path. The catalyst-containing portion includes an endothermic reaction-promoting catalyst capable of promoting an endothermic reaction involving the first component, and an exothermic reaction-promoting catalyst capable of promoting an exothermic reaction between a reaction product of the first component and the second component, and the dispersion ratio of the exothermic reaction-promoting catalyst calculated by cross-sectional analysis of the catalyst-containing portion is 0.60 or greater. [2] In the reactor described above in [1], the dispersion ratio of the exothermic reaction-promoting catalyst is less than 0.90. [3] In the above [1] or [2], the reactor is a methane production reactor; the first component is ammonia; the second component is carbon dioxide; the endothermic reaction-promoting catalyst is an ammonia decomposition catalyst capable of promoting a reaction of decomposing ammonia to produce hydrogen; and the exothermic reaction-promoting catalyst is a methanation reaction catalyst capable of promoting a reaction of producing methane from hydrogen and carbon dioxide. [4] In any of the above [1] to [3], the reactor comprises a substrate defining the gas flow path; and the catalyst-containing portion is a catalyst-containing layer provided on the surface of the substrate so as to face the gas flow path. [5] In the above [4], the substrate is a honeycomb-shaped substrate having partition walls defining a plurality of cells; at least a portion of the plurality of cells includes the gas flow path; and the catalyst-containing layer is provided on the surface of the partition wall. [6] In the above [4] or [5], the substrate is made of ceramic. [7] In any of the above [4] to [6], the geometric surface area of ​​the substrate is 3.0 cm ２ / cm ３ ~50.0cm ２ / cm ３[8] In any of the above [3] to [7], the methanation reaction catalyst has an average secondary particle diameter of 0.1 μm to 20 μm, and the ammonia decomposition catalyst has an average secondary particle diameter of 0.1 μm to 100 μm. [9] In any of the above [3] to [8], the ammonia decomposition catalyst has an active component containing a transition metal.

[10] In the above [9], the transition metal includes Co, Fe, Pt, Ru, Rh, Pd, Ni, Cu, Ag, Au, Ir, or a combination thereof.

[11] In the above

[10] , the transition metal includes Ni, Ru, Co, or a combination thereof.

[12] In any of [9] to

[11] above, the ammonia decomposition catalyst further comprises a carrier supporting the active component; the carrier comprises aluminum oxide, titanium oxide, magnesium oxide, silicon oxide, yttrium oxide, zirconium oxide, or a composite oxide thereof, or calcium carbonate.

[13] In any of [3] to

[12] above, the methanation reaction catalyst has an active component comprising a transition metal.

[14] In

[13] above, the transition metal comprises Co, Fe, Pt, Ru, Rh, Pd, Ni, Cu, Ag, Au, Ir, or a combination thereof.

[15] In

[14] above, the transition metal comprises Ni, Ru, Co, or a combination thereof.

[16] In any one of the above

[13] to

[15] , the methanation reaction catalyst further comprises a support that supports the active component; the support comprises cerium oxide, silicon oxide, zirconium oxide, yttrium oxide, aluminum oxide, or a composite oxide thereof.

[0008] According to an embodiment of the present invention, it is possible to realize a reactor that is used in a process including two or more elementary reactions, i.e., an exothermic reaction and an endothermic reaction, and that has excellent reaction efficiency and suppresses catalyst deterioration.

[0009] 1 is a schematic perspective view of a methane production reactor according to one embodiment of the present invention;FIG. 2 is a schematic cross-sectional view of the methane production reactor of FIG.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Note that the drawings are drawn schematically for ease of viewing, and thickness, length, width, shape, ratio, etc. do not accurately reflect the actual shape. Furthermore, in this specification, "mass" and "weight" can be read interchangeably.

[0011] A. Overview of the Reactor A reactor according to an embodiment of the present invention is used in a process involving two or more elementary reactions, namely, an exothermic reaction and an endothermic reaction. The reactor includes a gas flow path to which a source gas containing a first component and a second component is supplied, and a catalyst-containing portion arranged to be in contact with the source gas supplied to the gas flow path. The catalyst-containing portion includes an endothermic reaction-promoting catalyst capable of promoting an endothermic reaction involving the first component (e.g., a decomposition reaction of the first component) and an exothermic reaction-promoting catalyst capable of promoting an exothermic reaction between a reaction product (e.g., a decomposition product) of the first component and the second component. The exothermic reaction may be a reaction that produces a final product. In an embodiment of the present invention, the endothermic reaction-promoting catalyst and the exothermic reaction-promoting catalyst are dispersed in the catalyst-containing portion, and the dispersion ratio of the exothermic reaction-promoting catalyst calculated by cross-sectional analysis of the catalyst-containing portion is 0.60 or greater. In other words, the endothermic reaction-promoting catalyst and the exothermic reaction-promoting catalyst are dispersed with very high uniformity in the catalyst-containing portion. Therefore, localized heat generation due to the exothermic reaction can be suppressed. As a result, the temperature distribution in the catalyst-containing portion can be made uniform, thereby achieving excellent reaction efficiency and suppressing catalyst deterioration.

[0012] The dispersion ratio of the exothermic reaction-accelerating catalyst is typically 0.61 or more, preferably 0.62 or more, more preferably 0.63 or more, even more preferably 0.64 or more, particularly preferably 0.65 or more, and particularly preferably 0.66 or more. The dispersion ratio may be, for example, 0.90 or less, or may be, for example, 0.80 or less, or may be, for example, 0.75 or less. Cross-sectional analysis of the catalyst-containing portion to calculate the dispersion ratio can typically be performed as follows: (i) a scanning electron microscope image of a cross section obtained by cutting the catalyst-containing portion in a predetermined direction is obtained; and (ii) the obtained scanning electron microscope image is subjected to binarization analysis using brightness as a threshold to obtain a binarized image. The threshold for binarization is set using Otsu's binarization as a discriminant analysis method. In the binary image, the portion corresponding to the exothermic reaction-promoting catalyst may be a white region or a black region depending on the type of exothermic reaction-promoting catalyst, the combination of the exothermic reaction-promoting catalyst and the endothermic reaction-promoting catalyst, etc.; (iii) from the obtained binary image, the total area of ​​the region showing the exothermic reaction-promoting catalyst, the average diameter of the granules contained in that region, and the number of granule elements are obtained; (iv) assuming that the periphery of the granules in the above cross section is a circle, the area per granule is calculated from the average diameter of the granules; (v) the total area of ​​the region showing the exothermic reaction-promoting catalyst is divided by the area per granule to calculate the ideal number of granules; (vi) the number of granule elements is divided by the ideal number to calculate the dispersion rate.

[0013] As described above, the reactor according to the embodiment of the present invention is used in processes involving two or more elementary reactions, one exothermic and one endothermic, such as ammonia methanation, 2-propanol dehydrogenation, and direct FT synthesis.

[0014] For ease of understanding, a methane production reactor used for ammonia methanation will be described below as an example. As described above, it will be apparent to those skilled in the art that the embodiments of the present invention can be used in processes that include two or more elementary reactions, that is, an exothermic reaction and an endothermic reaction, similar to ammonia methanation.

[0015] B. Methane Production Reactor B-1. Overview of the Methane Production Reactor A methane production reactor is typically used for ammonia methanation, as described above. Specifically, the first component in the feed gas is ammonia, and the second component is carbon dioxide. Furthermore, the endothermic reaction-promoting catalyst is an ammonia decomposition catalyst capable of promoting a reaction that decomposes ammonia to produce hydrogen; and the exothermic reaction-promoting catalyst is a methanation reaction catalyst capable of promoting a reaction that produces methane from carbon dioxide and hydrogen obtained by ammonia decomposition. In a methane production reactor according to an embodiment of the present invention, the dispersion of the methanation reaction catalyst in the catalyst-containing portion is 0.60 or more, i.e., the ammonia decomposition catalyst and the methanation reaction catalyst are dispersed with very high uniformity, thereby suppressing localized heat generation due to the methanation reaction. As a result, the temperature distribution in the catalyst-containing portion can be made uniform, thereby achieving an excellent methane yield and suppressing catalyst degradation.

[0016] FIG. 1 is a schematic perspective view of a methane production reactor according to one embodiment of the present invention; and FIG. 2 is a schematic cross-sectional view of the methane production reactor of FIG. 1. The illustrated methane production reactor 100 includes a substrate 1 and a catalyst-containing portion 2. The substrate 1 is typically made of ceramics. The substrate 1 is typically honeycomb-shaped (hereinafter, the substrate may be referred to as a honeycomb-shaped substrate). The honeycomb-shaped substrate 1 includes partition walls 12 that define a plurality of cells 13. The partition walls 12 typically contain cordierite. At least a portion of the cells 13 include gas flow channels 14.

[0017] The catalyst-containing portion 2 in the illustrated example is a catalyst-containing layer. The catalyst-containing layer 2 is provided on the surface of the partition wall 12 so as to face the gas flow path 14. As described above, an ammonia decomposition catalyst and a methanation reaction catalyst are dispersed in the catalyst-containing layer 2. Therefore, the ammonia decomposition catalyst and the methanation reaction catalyst are typically particulate. As described above, the dispersion ratio of the methanation reaction catalyst in the catalyst-containing layer 2 is 0.60 or more. The catalyst-containing layer 2 is typically formed by applying a slurry in which ammonia decomposition catalyst particles and methanation reaction catalyst particles are dispersed to a substrate (substantially the partition wall) and drying the slurry. A method for manufacturing a reactor will be described later. This formation method can form a catalyst-containing layer with the above-described configuration. With the above-described configuration, when a raw material gas containing ammonia and carbon dioxide is passed through the gas flow path and supplied to the catalyst-containing portion, ammonia can efficiently come into contact with the ammonia decomposition catalyst, and the chemical reaction represented by the following formula (1) can proceed smoothly. Furthermore, since the products of the reaction, hydrogen and carbon dioxide, can be brought into contact with the methanation catalyst efficiently, the chemical reaction shown in the following formula (2) can proceed smoothly. ３ →12H ２ +4N ２ ... (1) CO ２ +4H ２ →CH ４ +2H ２ O... (2)

[0018] The catalyst-containing portion may have any suitable configuration as long as the effects of the present invention can be obtained. For example, the catalyst-containing portion may have a configuration in which pellets of a hybrid catalyst that have been subjected to a highly dispersed (uniformly dispersed) process are filled in the gas flow path.

[0019] B-2. Honeycomb Substrate The honeycomb substrate 1 typically has a flow-through honeycomb structure. The honeycomb substrate 1 may have any appropriate shape (overall shape). Examples of the shape of the honeycomb substrate 1 include a cylindrical shape with a circular bottom, an elliptical cylindrical shape with an elliptical bottom, a rectangular prism with a polygonal bottom, and a cylindrical shape with an irregular bottom. In one embodiment, the honeycomb substrate 1 has a cylindrical shape. The outer diameter and length of the honeycomb substrate 1 can be appropriately set depending on the purpose. Although not shown, the honeycomb substrate 1 may have a hollow region at the center in a cross section perpendicular to the longitudinal direction.

[0020] In the illustrated example, the honeycomb substrate 1 includes an outer peripheral wall 11 and partition walls 12 located inside the outer peripheral wall 11. The outer peripheral wall 11 and the partition walls 12 may be formed integrally or separately. In the illustrated example, the outer peripheral wall 11 and the partition walls 12 are formed integrally. Note that the honeycomb substrate 1 does not necessarily have to include the outer peripheral wall 11. In this case, the honeycomb substrate 1 is composed of the partition walls 12.

[0021] The cell density of the honeycomb substrate 1 is preferably 30 cpsi or more, more preferably 200 cpsi or more, even more preferably 400 cpsi or more, particularly preferably 600 cpsi or more, and particularly preferably 800 cpsi or more. On the other hand, the upper limit of the cell density of the honeycomb substrate 1 is typically 1200 cpsi. In this specification, the "cell density of the honeycomb substrate" means the cell density of the cross section in the length direction (direction in which the cells extend) of the honeycomb substrate, and "cpsi" refers to the cell density of 6.4516 cm of the cross section. ２ This refers to the number of cells per square inch.

[0022] The honeycomb substrate 1 has a geometric surface area of ​​preferably 3.0 cm ２ / cm ３ More preferably, 5.0 cm or more. ２ / cm ３ More preferably, it is 7.0 cm or more. ２ / cm ３ More preferably, it is 10.0 cm or more. ２ / cm ３More preferably, it is 30.0 cm or more. ２ / cm ３ The geometric surface area of ​​the honeycomb substrate is, for example, 50.0 cm ２ / cm ３ It can be less than, for example, 45.0 cm ２ / cm ３ or less. Therefore, typically, the outer peripheral wall and the partition walls also have such a geometric surface area. If the geometric surface area of ​​the honeycomb substrate is in this range, the frequency of contact between ammonia and the ammonia decomposition catalyst, and the frequency of contact between hydrogen and carbon dioxide and the methanation reaction catalyst can be significantly increased. As a result, an extremely excellent methane yield can be realized.

[0023] The thermal conductivity of the honeycomb substrate 1 may be, for example, 0.60 W / m·k to 200 W / m·k. Therefore, the outer peripheral wall and the partition walls may also typically have such a thermal conductivity. In one embodiment, the thermal conductivity may preferably be 0.70 W / m·k to 1.00 W / m·k. In another embodiment, the thermal conductivity may preferably be 10.0 W / m·k to 20.0 W / m·k. In yet another embodiment, the thermal conductivity may preferably be 100 W / m·k to 150 W / m·k. The thermal conductivity may preferably be 5.00 W / m·k or more. If the thermal conductivity is in such a range, local heat generation due to the methanation reaction can be further suppressed.

[0024] The outer peripheral wall 11 has a cylindrical shape. The thickness of the outer peripheral wall 11 can be appropriately set depending on the application of the methane production reactor. The thickness of the outer peripheral wall 11 can be, for example, 1 mm to 10 mm, or can be, for example, 2 mm to 8 mm. As described above, the honeycomb substrate 1 does not necessarily have to include the outer peripheral wall 11.

[0025] As described above, the partition walls 12 define a plurality of cells 13. The cells 13 extend in the longitudinal direction (axial direction) of the honeycomb substrate 1 from the first end face 1a (inlet end face) to the second end face 1b (outlet end face) of the honeycomb substrate 1 (see FIG. 2). The cells 13 have any appropriate shape in a cross section perpendicular to the longitudinal direction of the methane production reactor 100. Examples of the cross-sectional shape of the cells include a triangle, a rectangle, a pentagon, a polygon having hexagons or more, a circle, and an ellipse. The cross-sectional shapes and sizes of the cells may all be the same, or at least some of them may be different. Among such cross-sectional shapes of the cells, a rectangle is preferred, and a square or rectangle is more preferred.

[0026] As will be described in detail later, gas flow channels 14 are formed inside the cells 13. The gas flow channels 14 are spaces formed inside the cells 13, and extend from the first end face 1a (inlet end face) to the second end face 1b (outlet end face) in the same manner as the cells 13. The cross-sectional shape of the gas flow channels 14 may be the same as that of the cells 13 described above, preferably a quadrangle, and more preferably a square or rectangle. The cross-sectional shapes and sizes of the gas flow channels 14 may all be the same, or at least some may be different.

[0027] In the illustrated example, the partition walls 12 have first partition walls 12a and second partition walls 12b that are perpendicular to each other, and the first partition walls 12a and the second partition walls 12b define a plurality of cells 13. The cross-sectional shape of the cells 13 is quadrangular except for the portions where the first partition walls 12a and the second partition walls 12b contact the outer peripheral wall 11. The configuration of the partition walls is not limited to the above-described partition walls 12. The partition walls may have first partition walls extending in the radial direction and second partition walls extending in the circumferential direction, which define a plurality of cells.

[0028] The thickness of the partition wall 12 can be set arbitrarily and appropriately. When an outer peripheral wall is present, the thickness of the partition wall 12 is typically thinner than the thickness of the outer peripheral wall 11. The thickness of the partition wall 12 is, for example, 0.0254 mm (1.0 mil) or more, preferably 0.0635 mm (2.5 mil) or more. On the other hand, the thickness of the partition wall 12 is, for example, 0.508 mm (20 mil) or less, preferably 0.254 mm (10 mil) or less, more preferably 0.2032 mm (8.0 mil) or less, and even more preferably 0.127 mm (5.0 mil) or less. When the thickness of the partition wall is in this range, the mechanical strength of the methane production reactor can be made sufficient, and the cell density can be adjusted to the above-mentioned range. The thickness of the partition wall is measured, for example, by cross-sectional observation using a scanning electron microscope (SEM).

[0029] The partition walls 12 may or may not have pores. When the partition walls have pores, the average pore diameter in the partition walls 12 can be appropriately set depending on the purpose. The average pore diameter in the partition walls 12 is, for example, 0.1 μm or more, preferably 1 μm or more, and more preferably 5 μm or more. On the other hand, the average pore diameter in the partition walls 12 is, for example, 60 μm or less, and preferably 50 μm or less. The average pore diameter is measured by, for example, mercury porosimetry. When the partition walls have pores, the porosity of the partition walls 12 can be appropriately set depending on the purpose. The porosity of the partition walls 12 is, for example, 0.1% or more. On the other hand, the porosity of the partition walls 12 is, for example, 70% or less, preferably 65% ​​or less, and more preferably 50% or less. The porosity can be measured by, for example, mercury porosimetry. When the average pore size and / or porosity of the partition walls 12 are within these ranges, the amounts of the ammonia decomposition catalyst and the methanation reaction catalyst supported on the partition walls can be improved.

[0030] The bulk density of the partition walls 12 can be appropriately set depending on the purpose. The bulk density of the partition walls 12 is, for example, 1.0 g / cm ３ ~3.0 g / cm ３ The bulk density is measured by, for example, the Archimedes method.

[0031] Examples of ceramic materials that can be used to form the partition walls 12 include zirconia-based materials, alumina-titanium carbide-based composite materials, Si-SiC-based composite materials, aluminum nitride, aluminum oxide, silicon nitride, silicon carbide, zirconia, cordierite, and mullite. These ceramic materials can be used alone or in combination. Of these ceramic materials, cordierite and Si-SiC-based composite materials are preferred.

[0032] B-3. ​​Catalyst-Containing Portion In one embodiment, the catalyst-containing portion 2 is a catalyst-containing layer as shown in the illustrated example, and is formed on the surface of the partition wall 12. In the methane production reactor 100, the gas flow passage 14 is formed in a portion of the cross section of the cell 13 where the catalyst-containing layer 2 is not formed (typically the central portion). The catalyst-containing layer 2 may be formed on the entire inner surface of the partition wall 12 (i.e., so as to surround the gas flow passage 14) as shown in the illustrated example, or may be formed on a portion of the surface of the partition wall. When the catalyst-containing layer 2 is formed on the entire inner surface of the partition wall 12, the methane yield can be stably improved. Note that, as described above, the catalyst-containing portion may have a configuration in which the gas flow passage is filled with pellets of a hybrid catalyst that has been subjected to a high-level dispersion treatment (uniform dispersion treatment).

[0033] The catalyst-containing layer will be described below.

[0034] In the catalyst-containing layer 2, typically, as described above, the ammonia decomposition catalyst and the methanation catalyst are dispersed, and the dispersion ratio of the methanation catalyst is 0.60 or more. The ammonia decomposition catalyst and the methanation catalyst may each have any appropriate shape. Typically, the ammonia decomposition catalyst and the methanation catalyst each have a particulate shape. These catalyst particles may be aggregates formed by aggregating multiple particles. With this configuration, mesopores can be formed in the catalyst-containing layer 2.

[0035] When the ammonia decomposition catalyst and the methanation reaction catalyst are each particulate, the average secondary particle diameter of the ammonia decomposition catalyst particles is preferably 0.1 μm to 100 μm, more preferably 1 μm to 50 μm. The average secondary particle diameter of the methanation reaction catalyst particles is preferably 0.1 μm to 20 μm, more preferably 1 μm to 10 μm. Hybrid catalysts often result in uneven dispersion of the ammonia decomposition catalyst and the methanation reaction catalyst in the pellets. This is often due to differences in size (e.g., average secondary particle diameter) between the ammonia decomposition catalyst particles and the methanation reaction catalyst particles. According to embodiments of the present invention, even if the average secondary particle diameters of the ammonia decomposition catalyst particles and the methanation reaction catalyst particles differ as described above, uniform dispersion can be achieved. As a result, excellent reaction efficiency (here, methane yield) can be achieved, and catalyst degradation can be suppressed.

[0036] The ammonia decomposition catalyst typically contains a transition metal. The transition metal can function as an active component that promotes the ammonia decomposition reaction of the above formula (1). Examples of transition metals include cobalt (Co), iron (Fe), platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium (Pd), nickel (Ni), copper (Cu), silver (Ag), gold (Au), and iridium (Ir). These may be used alone or in combination of two or more. Preferred are Ni, Ru, Co, or a combination thereof. The transition metal may be contained in the ammonia decomposition catalyst in a metallic state, or may be contained in the ammonia decomposition catalyst as a metal salt. In one embodiment, the transition metal is in a metallic state.

[0037] The ammonia decomposition catalyst typically further contains a support for supporting the active component (transition metal) described above. Examples of the support include aluminum oxide, titanium oxide, magnesium oxide, silicon oxide, yttrium oxide, zirconium oxide, or composite oxides thereof, or calcium carbonate.

[0038] The transition metal content in the ammonia decomposition catalyst is, for example, 0.01 to 60 parts by mass, preferably 0.1 to 50 parts by mass, more preferably 0.5 to 30 parts by mass, and even more preferably 1 to 15 parts by mass, relative to 100 parts by mass of the support. If the transition metal content is within this range, the ammonia decomposition reaction can be stably promoted.

[0039] The methanation catalyst typically contains a transition metal. The transition metal can function as an active component that promotes the methanation reaction of formula (2) above. Examples of transition metals include Co, Fe, Pt, Ru, Rh, Pd, Ni, Cu, Ag, Au, and Ir. These may be used alone or in combination of two or more. Ni, Ru, Co, or a combination thereof is preferred. The transition metal may be contained in the methanation catalyst in a metallic state, or may be contained in the methanation catalyst as a metal salt. In one embodiment, the transition metal is in a metallic state.

[0040] The methanation catalyst typically further contains a support for supporting the active component (transition metal), such as cerium oxide, silicon oxide, zirconium oxide, yttrium oxide, aluminum oxide, or a composite oxide thereof.

[0041] The transition metal content in the methanation catalyst is, for example, 0.01 to 50 parts by mass, and preferably 1 to 25 parts by mass, relative to 100 parts by mass of the support. When the transition metal content is within this range, the methanation reaction can be stably promoted.

[0042] The catalyst-containing layer 2 may contain an additive in addition to the ammonia decomposition catalyst and the methanation reaction catalyst.

[0043] The total content of the ammonia decomposition catalyst and the methanation reaction catalyst in the catalyst-containing layer 2 is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The upper limit of the total content may be, for example, 100% by mass. When the total content of the ammonia decomposition catalyst and the methanation reaction catalyst in the catalyst-containing layer is within this range, a high methane yield can be achieved.

[0044] The content of the ammonia decomposition catalyst in the catalyst-containing layer 2 is preferably 25% by mass to 90% by mass, and more preferably 30% by mass to 85% by mass. The content of the methanation reaction catalyst in the catalyst-containing layer 2 is preferably 5% by mass to 50% by mass, and more preferably 15% by mass to 40% by mass. The content ratio (A / M) (weight ratio) of the ammonia decomposition catalyst A to the methanation reaction catalyst M in the catalyst-containing layer 2 is preferably 50 / 50 to 95 / 5, more preferably 55 / 45 to 90 / 10, and even more preferably 60 / 40 to 85 / 15. When the content ratio of the ammonia decomposition catalyst to the methanation reaction catalyst in the catalyst-containing layer is within this range, a high methane yield can be achieved.

[0045] The average pore size in the catalyst-containing layer 2 is, for example, 0.01 μm to 50 μm, and preferably 1 μm to 30 μm.

[0046] The BET specific surface area of ​​the catalyst-containing layer 2 is, for example, 1 m ２ / g to 2000m ２ / g, preferably 10m ２ / g~1500m ２ / g.

[0047] B-4. Manufacturing Method of Methane Production Reactor Next, a description will be given of a manufacturing method of the methane production reactor 100. The manufacturing method of the methane production reactor 100 includes a step of preparing a honeycomb substrate 1; and a step of forming a catalyst-containing layer 2 on the partition walls 12 of the honeycomb substrate 1.

[0048] The honeycomb substrate 1 can be produced by the following method. First, a binder and water or an organic solvent are added as needed to a material powder containing, for example, cordierite powder, and the resulting mixture is kneaded to form a clay. The clay is then molded (typically by extrusion molding) into a desired shape, dried, and then fired as needed to produce the honeycomb substrate 1. It goes without saying that the material powder used is a powder appropriate for the constituent material of the honeycomb substrate.

[0049] Next, the catalyst-containing layer 2 is formed on the partition wall 12. The method for forming the catalyst-containing layer 2 is not particularly limited, and any appropriate method may be adopted. In one embodiment, the step of forming the catalyst-containing layer 2 includes, in order, a step of preparing ammonia decomposition catalyst particles and methanation reaction catalyst particles (hereinafter, these may be collectively referred to as catalyst particles); a step of preparing a catalyst slurry in which the catalyst particles are dispersed; and a step of applying the catalyst slurry onto the partition wall 12.

[0050] In the step of preparing catalyst particles, for example, a carrier dispersion in which carrier particles are dispersed and an active component solution in which an active component (transition metal salt) is dissolved are prepared. Hereinafter, the ammonia decomposition catalyst particles and the methanation reaction catalyst particles will be described. As an example, the ammonia decomposition catalyst particles will be described in which the active component is nickel and the carrier is aluminum oxide; as an example, the methanation reaction catalyst particles will be described in which the active component is nickel and the carrier is cerium oxide.

[0051] <Ammonia decomposition catalyst particles> To prepare a carrier dispersion, carrier particles are added to a dispersion medium and stirred. The average secondary particle diameter of the aluminum oxide particles is, for example, 0.1 μm to 100 μm. The amount of aluminum oxide particles added is, for example, 5 parts by mass to 30 parts by mass per 100 parts by mass of the dispersion medium. Any appropriate solvent that does not dissolve aluminum oxide particles can be used as the dispersion medium. Examples of the dispersion medium include water and alcohols. The dispersion medium can be used alone or in combination. Of the dispersion mediums, water is preferred.

[0052] Next, a nickel salt is added to the carrier dispersion. This prepares a mixed solution of the carrier dispersion and the nickel salt solution. Examples of nickel salts include nickel nitrate, nickel acetate, nickel sulfate, and nickel oxalate, and nickel nitrate is preferred. The nickel salts may be used alone or in combination. The amount of nickel salt added is, for example, 0.01 to 20 parts by mass of nickel per 100 parts by mass of the solvent.

[0053] Next, the mixed liquid is heated while stirring to evaporate the dispersion medium and the solvent. This results in a solid. The solid is then heated. The heating temperature of the solid is, for example, 300°C to 700°C, preferably 400°C to 600°C. The heating time of the solid is, for example, 1 hour to 10 hours, preferably 2 hours to 4 hours. The heating of the solid may be carried out in the atmosphere, or in a reducing atmosphere (typically a hydrogen atmosphere). The heating of the solid is preferably carried out in the atmosphere.

[0054] In this manner, ammonia decomposition catalyst particles are prepared.

[0055] <Methanation reaction catalyst particles> To prepare a carrier dispersion, carrier particles are added to a dispersion medium and stirred, similarly to the case of ammonia decomposition catalyst particles. The average secondary particle diameter of the cerium oxide particles is, for example, 0.1 μm to 20 μm. The amount of cerium oxide particles added is, for example, 5 parts by mass to 30 parts by mass per 100 parts by mass of the dispersion medium. The dispersion medium is as described for the ammonia decomposition catalyst particles.

[0056] The mixed solution of the carrier dispersion and the nickel salt solution is prepared as described for the ammonia decomposition catalyst particles.

[0057] Next, the mixed liquid is heated while stirring to evaporate the dispersion medium and the solvent. This results in a solid. The solid is then heated. The heating temperature of the solid is, for example, 300°C to 700°C, preferably 400°C to 600°C. The heating time of the solid is, for example, 1 hour to 10 hours, preferably 2 hours to 4 hours. The heating of the solid may be carried out in the atmosphere, or in a reducing atmosphere (typically a hydrogen atmosphere). The heating of the solid is preferably carried out in the atmosphere.

[0058] In this manner, methanation reaction catalyst particles are prepared.

[0059] After preparing the catalyst particles as described above, a catalyst slurry is prepared. In the step of preparing the catalyst slurry, the catalyst particles are added to a dispersion medium and stirred. If necessary, after adding the catalyst particles to the dispersion medium, a pulverization treatment using a ball mill or the like may be performed. Any appropriate solvent that does not dissolve the catalyst particles may be used as the dispersion medium. Examples of the dispersion medium include water and alcohols. The dispersion medium may be used alone or in combination. Among the dispersion mediums, water is preferred. In this way, the catalyst particles are dispersed in the dispersion medium, and the catalyst slurry is prepared.

[0060] The content of catalyst particles in the catalyst slurry is, for example, 5% by mass to 50% by mass, and preferably 10% by mass to 40% by mass. When the content of catalyst particles in the catalyst slurry is in this range, the catalyst slurry can be smoothly applied onto the partition walls, and a catalyst-containing layer can be stably formed.

[0061] Next, in the step of applying the catalyst slurry, the catalyst slurry is applied onto the partition walls 12 of the honeycomb substrate 1 by any appropriate method. In one embodiment, the honeycomb substrate 1 is immersed in the catalyst slurry. This is a simple method, but the catalyst slurry can be sufficiently applied to the surfaces of the partition walls. However, the application of the catalyst slurry is not limited to this. For example, the catalyst slurry may be circulated through the cells 13 of the honeycomb substrate 1. This method also allows the catalyst slurry to be applied onto the partition walls.

[0062] Next, the coating film of the catalyst slurry formed on the partition walls 12 is dried at any appropriate heating temperature, as necessary. As a result, the catalyst-containing layer 2 is formed on the surface of the partition walls 12. The above-mentioned step of applying the catalyst slurry and the step of drying the coating film may be repeated multiple times until the thickness of the catalyst-containing layer 2 reaches a desired range.

[0063] In this manner, the methane production reactor 100 including the honeycomb substrate 1 and the catalyst-containing layer 2 is manufactured.

[0064] C. Methane Production Method The methane production reactor 100 described above can be suitably used for producing methane (ammonia methanation) by using ammonia as a hydrogen source and reacting hydrogen generated from the ammonia with carbon dioxide. The methane production reactor 100 can produce methane by supplying a raw material gas containing carbon dioxide and ammonia (hydrogen source) to the catalyst-containing layer 2.

[0065] In one embodiment, the methane production reactor 100 is heated to a predetermined temperature. This predetermined temperature may typically be the ammonia decomposition initiation temperature and the methanation reaction initiation temperature. This temperature may be, for example, 300°C to 600°C. A raw material gas containing ammonia and carbon dioxide is supplied to the gas flow path 14 of the methane production reactor 100 heated to such a temperature. As a result, first, the ammonia decomposition reaction of the above formula (1) starts, and when hydrogen is produced by the decomposition of ammonia, the methanation reaction of the above formula (2) starts. Note that, since the ammonia decomposition reaction is an endothermic reaction, typically, the heating of the methane production reactor may be continued in order to continue the ammonia decomposition reaction and the methanation reaction.

[0066] The ammonia content in the raw material gas is, for example, 25 to 90% by volume, and preferably 70 to 90% by volume. The carbon dioxide content in the raw material gas is, for example, 5 to 50% by volume, and preferably 10 to 30% by volume.

[0067] In one embodiment, the source gas may contain a balance of nitrogen, argon, helium, or other rare gases.

[0068] The flow rate of the source gas may be any appropriate flow rate depending on the purpose.

[0069] As a result of the above-described ammonia decomposition reaction and methanation reaction continuing, a methane-containing gas is continuously discharged from the gas flow path 14 of the methane production reactor 100. The methane-containing gas contains at least methane. The methane-containing gas may also contain unreacted remaining raw material gas.

[0070] According to an embodiment of the present invention, the dispersion ratio of the methanation reaction catalyst in the catalyst-containing layer 2 of the methane production reactor 100 is as high as 0.60 or more (i.e., the methanation reaction catalyst and the ammonia decomposition catalyst are highly uniformly dispersed in the catalyst-containing layer 2), so that methane can be produced with an excellent methane yield.

[0071] The methane yield is, for example, 47% or more, typically 50% or more, preferably 54% or more, more preferably 58% or more, even more preferably 60% or more, particularly preferably 62% or more, and especially preferably 64% or more. The higher the methane yield, the better, and the upper limit thereof may be, for example, 90%, or 85%, or 80%, or 75%, or 70%.

[0072] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" are by mass unless otherwise specified.

[0073] <Production Example 1: Preparation of honeycomb substrate> A clay containing cordierite was extruded and then dried to prepare a honeycomb substrate having the shape shown in Figures 1 and 2 (without a catalyst-containing layer formed thereon). The honeycomb substrate had a cylindrical shape with a diameter of 20 mm and a length of 40 mm. The honeycomb substrate had partition walls defining a plurality of cells and an outer peripheral wall surrounding the partition walls. The cross-sectional shape of the cells was rectangular. The geometric surface area of ​​the honeycomb substrate was 11.3 cm ２ / cm ３ It was.

[0074] <Production Example 2: Preparation of honeycomb substrate> A clay containing 80 parts by mass of SiC powder and 20 parts by mass of metal Si powder was extruded, dried, and calcined in an oxidizing atmosphere at 550°C for 3 hours, and then fired in a non-oxidizing atmosphere at 1450°C for 2 hours. In this manner, a honeycomb substrate having the shape shown in Figures 1 and 2 (without a catalyst-containing layer) was prepared. The honeycomb substrate had a cylindrical shape with a diameter of 20 mm and a length of 40 mm. The honeycomb substrate had partition walls defining a plurality of cells and an outer peripheral wall surrounding the partition walls. The cross-sectional shape of the cells was rectangular. The geometric surface area of ​​the honeycomb substrate was 11.3 cm ２ / cm ３ It was.

[0075] <Production Example 3: Preparation of Honeycomb Substrate> A clay containing SiC powder was extruded and then dried to prepare a dried honeycomb body. Meanwhile, a material powder containing Si powder was press-molded and then dried to obtain a Si supply body. Next, the Si supply body was brought into contact with the dried honeycomb body and heated at 1500°C for 4 hours under reduced pressure (200 Pa) to impregnate the dried honeycomb body with molten metal containing Si. In this manner, a honeycomb substrate having the shape shown in Figures 1 and 2 (without a catalyst-containing layer) was prepared. The honeycomb substrate was composed of a dense body of Si-SiC composite material. The honeycomb substrate had a cylindrical shape with a diameter of 20 mm and a length of 40 mm. The honeycomb substrate had partition walls defining a plurality of cells and an outer peripheral wall surrounding the partition walls. The cross-sectional shape of the cells was rectangular. The geometric surface area of ​​the honeycomb substrate was 10.8 cm. ２ / cm ３ It was.

[0076] <Production Example 4-1: Preparation of ammonia decomposition catalyst particles> Aluminum oxide particles (manufactured by Sumitomo Chemical Co., Ltd.) were introduced into distilled water and then stirred at room temperature under reduced pressure for 12 hours. This resulted in a dispersion of aluminum oxide particles. Next, nickel (II) nitrate hexahydrate was added to the dispersion of aluminum oxide particles and stirred at room temperature (23°C) for 2 hours. Thereafter, the mixture of the dispersion and aqueous solution was placed in an evaporator (80°C) to evaporate the water. Next, the remaining solid was heated at 600°C for 2 hours. This resulted in ammonia decomposition catalyst particles. The ammonia decomposition catalyst particles contained nickel (Ni) and aluminum oxide supporting nickel (Ni). The Ni content in the ammonia decomposition catalyst particles was 10 parts by mass relative to 90 parts by mass of aluminum oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 12.6 μm.

[0077] <Production Example 4-2: Preparation of ammonia decomposition catalyst particles> Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 4-1, except that magnesium oxide particles (manufactured by Ube Material Industries, Ltd.) were used instead of aluminum oxide particles. The ammonia decomposition catalyst particles contained nickel (Ni) and magnesium oxide supporting nickel (Ni). In the ammonia decomposition catalyst particles, the Ni content was 10 parts by mass relative to 90 parts by mass of magnesium oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 5.0 μm.

[0078] Production Example 4-3: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 4-1, except that titanium oxide particles were used instead of aluminum oxide particles. The ammonia decomposition catalyst particles contained nickel (Ni) and titanium oxide supporting nickel (Ni). In the ammonia decomposition catalyst particles, the Ni content was 10 parts by mass relative to 90 parts by mass of titanium oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 10.0 μm.

[0079] <Production Example 4-4: Preparation of ammonia decomposition catalyst particles> Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 4-1, except that aluminum oxide particles were replaced with silicon oxide particles (manufactured by Fuji Silysia Chemical Ltd.). The ammonia decomposition catalyst particles contained nickel (Ni) and silicon oxide supporting nickel (Ni). In the ammonia decomposition catalyst particles, the Ni content was 10 parts by mass relative to 90 parts by mass of silicon oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 6.0 μm.

[0080] Production Example 4-5: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 4-1, except that aluminum oxide particles were replaced with yttrium oxide particles. The ammonia decomposition catalyst particles contained nickel (Ni) and yttrium oxide supporting nickel (Ni). In the ammonia decomposition catalyst particles, the Ni content was 10 parts by mass relative to 90 parts by mass of yttrium oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 2.5 μm.

[0081] <Production Example 4-6: Preparation of ammonia decomposition catalyst particles> Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 4-1, except that aluminum oxide particles were replaced with zirconium oxide particles (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.). The ammonia decomposition catalyst particles contained nickel (Ni) and zirconium oxide supporting nickel (Ni). In the ammonia decomposition catalyst particles, the Ni content was 10 parts by mass relative to 90 parts by mass of zirconium oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 4.5 μm.

[0082] Production Example 5-1: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 4-1, except that nickel (II) nitrate hexahydrate was replaced with a ruthenium nitrate aqueous solution. The ammonia decomposition catalyst particles contained ruthenium (Ru) and aluminum oxide supporting ruthenium (Ru). In the ammonia decomposition catalyst particles, the Ru content was 10 parts by mass relative to 90 parts by mass of aluminum oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 13.4 μm.

[0083] Production Example 5-2: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 5-1, except that magnesium oxide particles were used instead of aluminum oxide particles. The ammonia decomposition catalyst particles contained ruthenium (Ru) and magnesium oxide supporting ruthenium (Ru). In the ammonia decomposition catalyst particles, the content of Ru was 10 parts by mass relative to 90 parts by mass of magnesium oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 5.4 μm.

[0084] Production Example 5-3: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 5-1, except that titanium oxide particles were used instead of aluminum oxide particles. The ammonia decomposition catalyst particles contained ruthenium (Ru) and titanium oxide supporting ruthenium (Ru). In the ammonia decomposition catalyst particles, the content of Ru was 10 parts by mass relative to 90 parts by mass of titanium oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 10.5 μm.

[0085] Production Example 5-4: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 5-1, except that aluminum oxide particles were replaced with silicon oxide particles. The ammonia decomposition catalyst particles contained ruthenium (Ru) and silicon oxide supporting ruthenium (Ru). In the ammonia decomposition catalyst particles, the content of Ru was 10 parts by mass relative to 90 parts by mass of silicon oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 6.5 μm.

[0086] Production Example 5-5: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 5-1, except that aluminum oxide particles were replaced with yttrium oxide particles. The ammonia decomposition catalyst particles contained ruthenium (Ru) and yttrium oxide supporting ruthenium (Ru). In the ammonia decomposition catalyst particles, the content of Ru was 10 parts by mass relative to 90 parts by mass of yttrium oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 2.4 μm.

[0087] Production Example 5-6: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 5-1, except that aluminum oxide particles were replaced with zirconium oxide particles. The ammonia decomposition catalyst particles contained ruthenium (Ru) and zirconium oxide supporting ruthenium (Ru). In the ammonia decomposition catalyst particles, the content of Ru was 10 parts by mass relative to 90 parts by mass of zirconium oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 4.9 μm.

[0088] Production Example 6: Preparation of ammonia decomposition catalyst particles Ammonia decomposition catalyst particles were obtained in the same manner as in Production Example 4-1, except that nickel (II) nitrate hexahydrate was changed to cobalt (II) nitrate hexahydrate. The ammonia decomposition catalyst particles contained cobalt (Co) and aluminum oxide supporting cobalt (Co). In the ammonia decomposition catalyst particles, the Co content was 10 parts by mass relative to 90 parts by mass of aluminum oxide. The average secondary particle diameter of the ammonia decomposition catalyst particles was 14.1 μm.

[0089] <Production Example 7: Preparation of methanation catalyst particles> Cerium (IV) oxide particles (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.) were introduced into distilled water and then stirred under reduced pressure at room temperature (23°C) for 12 hours. This yielded a dispersion of cerium oxide particles. Next, nickel (II) nitrate hexahydrate was added to the dispersion of cerium oxide particles and stirred at room temperature (23°C) for 2 hours. The mixture of the dispersion and aqueous solution was then placed in an evaporator (80°C) to evaporate the water. The remaining solid was then heated at 600°C for 2 hours. This yielded methanation catalyst particles. The methanation catalyst particles contained nickel (Ni) and cerium (IV) oxide supporting nickel (Ni). The Ni content in the methanation catalyst particles was 20 parts by mass relative to 80 parts by mass of cerium oxide. The average secondary particle diameter of the methanation catalyst particles was 5.6 μm.

[0090] Production Example 8: Preparation of methanation catalyst particles Methanation catalyst particles were obtained in the same manner as in Production Example 7, except that nickel (II) nitrate hexahydrate was replaced with a ruthenium nitrate aqueous solution. The methanation catalyst particles contained ruthenium (Ru) and cerium (IV) oxide supporting ruthenium (Ru). In the methanation catalyst particles, the Ru content was 20 parts by mass relative to 80 parts by mass of cerium oxide. The average secondary particle diameter of the methanation catalyst particles was 6.8 μm.

[0091] <Production Example 9: Production of hybrid catalyst pellets> The ammonia decomposition catalyst particles obtained in Production Example 4-1 and the methanation reaction catalyst particles obtained in Production Example 7 were mixed (dry) in a mortar at a weight ratio of 75 / 25. The resulting mixed catalyst was compression-molded at a pressure of 10 MPa using a Φ18 mold press. The molded body was then crushed to 5 mm or less to produce hybrid catalyst pellets.

[0092] <Production Example 10-1: Preparation of highly dispersed pellets of hybrid catalyst> A mixed catalyst was obtained in the same manner as in Production Example 9. The obtained mixed catalyst was dispersed in distilled water and wet-mixed, and the water was evaporated in a dryer (105°C), and then the mixture was mixed again in a mortar. The following procedure was followed in the same manner as in Production Example 9 to prepare highly dispersed pellets of the hybrid catalyst.

[0093] <Production Example 10-2: Preparation of highly dispersed pellets of hybrid catalyst> A mixed catalyst was obtained in the same manner as in Production Example 9. The obtained mixed catalyst was dispersed in distilled water, wet mixed and pulverized in a ball mill, the water was evaporated in a dryer (105°C), and then the mixture was mixed again in a mortar. After pulverization, the average secondary particle diameter of the ammonia decomposition catalyst particles was 0.2 μm, and the average secondary particle diameter of the methanation reaction catalyst particles was 0.1 μm. Highly dispersed pellets of the hybrid catalyst were prepared by the following procedure in the same manner as in Production Example 9.

[0094] Example 1 The ammonia decomposition catalyst particles obtained in Production Example 4-1 and the methanation reaction catalyst particles obtained in Production Example 7 were mixed (dry) in a mortar at a weight ratio of 75 / 25 to obtain catalyst particles. The obtained catalyst particles were dispersed in distilled water to prepare a catalyst slurry. The catalyst particle content in the catalyst slurry was 20 mass%. Next, the honeycomb substrate obtained in Production Example 1 was immersed in the catalyst slurry for 10 seconds under atmospheric pressure (0.1 MPa) and room temperature (23°C). The honeycomb substrate was then removed from the catalyst slurry. This resulted in the catalyst slurry being applied to the surfaces of the partition walls. The catalyst slurry applied to the surfaces of the partition walls was then heated at 100°C for 120 minutes to dry. The above immersion and drying were repeated to form a catalyst-containing layer on the surfaces of the partition walls. The catalyst-containing layer contained aggregates of catalyst particles. In this way, a methane production reactor equipped with a honeycomb substrate and a catalyst-containing layer as shown in Figures 1 and 2 was fabricated. The methane production reactor and methanation using the reactor were evaluated as follows. The results are shown in Table 1 together with the results of Examples 2 to 31 and Comparative Example 1 described below.

[0095] 1. Dispersion Ratio The cross section of the catalyst-containing layer of the obtained methane production reactor, cut in a direction perpendicular to the flow path of the honeycomb substrate, was imaged using a scanning electron microscope (Hitachi High-Technologies Corporation, product name "S-3400N", magnification: 100x). The obtained scanning electron microscope image was subjected to binarization analysis using brightness as a threshold to obtain a binarized image. The threshold for binarization was set using Otsu's binarization as a discriminant analysis method. From the obtained binarized image, the total area of ​​the region showing the methanation reaction catalyst, the average diameter of the granules contained in that region, and the number of granule elements were obtained. Assuming that the periphery of the granules in the cross section is a circle, the area per granule was calculated from the average diameter of the granules, and the total area of ​​the region showing the methanation reaction catalyst was divided by the area per granule to calculate the ideal number of granules. Finally, the number of granule elements was divided by the ideal number to calculate the dispersion ratio. The dispersion ratio of the catalyst-containing layer in this example was 0.67.

[0096] 2. Methanation Test The obtained methane production reactor was inserted into a reaction tube with an inner diameter of 21 mm. As a pretreatment for the reaction, the methane production reactor was heated to 500 °C using an electric furnace installed around the outer periphery of the reaction tube, and hydrogen gas was introduced into the reaction tube for reduction treatment. Then, the temperature of the electric furnace was lowered to 300 °C, and a mixed gas consisting of 72 vol% ammonia and 28 vol% carbon dioxide was introduced into the reaction tube as a raw material gas. The flow rate of the raw material gas introduced into the reaction tube was set to 119 mL / min. As a result, the raw material gas passed through each gas flow path provided in the methane production reactor, and methane-containing gas flowed out from the reaction tube. The introduction of the raw material gas was continued while maintaining the temperature of the methane production reactor at 550 °C. After the reaction stabilized, the methane concentration in the gas flowing out from the reaction tube was measured, and the methane yield was calculated. The methane yield in this example was 53.0%.

[0097] 3. Catalyst Degradation In the methanation test described in 2. above, the methane yield C immediately after the reaction stabilized ０ and C ０ Methane yield C after 100 hours from the measurement time １００ The maintenance rate calculated by the following formula was used as an index of catalyst deterioration. １００ / C ０ ×100 (%) Using the above retention rate, evaluation was performed according to the following criteria: No deterioration: retention rate of 80% or more Deterioration: retention rate of less than 80%

[0098] Examples 2 to 13 Methane production reactors equipped with a honeycomb substrate and a catalyst-containing layer as shown in Figures 1 and 2 were produced in the same manner as in Example 1, except that the honeycomb substrate, ammonia decomposition catalyst particles, and methanation reaction catalyst particles were changed to the configurations shown in Table 1. The obtained methane production reactors and methanation using the reactors were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0099] Example 14 The ammonia decomposition catalyst particles obtained in Production Example 4-1 and the methanation reaction catalyst particles obtained in Production Example 7 were mixed (dry) in a mortar at a weight ratio of 75 / 25 to obtain catalyst particles. The obtained catalyst particles were dispersed in distilled water and wet mixed and pulverized in a ball mill to prepare a catalyst slurry. After pulverization, the ammonia decomposition catalyst particles had an average secondary particle diameter of 0.2 μm, and the methanation reaction catalyst particles had an average secondary particle diameter of 0.1 μm. The following procedure was the same as in Example 1 to fabricate a methane production reactor equipped with a honeycomb substrate and a catalyst-containing layer as shown in FIGS. 1 and 2 . The obtained methane production reactor and methanation using this reactor were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0100] Examples 15 to 29 Methane production reactors equipped with a honeycomb substrate and a catalyst-containing layer as shown in Figures 1 and 2 were produced in the same manner as in Example 1, except that the honeycomb substrate, ammonia decomposition catalyst particles, and methanation reaction catalyst particles were changed to the configurations shown in Table 1. The obtained methane production reactors and methanation using these reactors were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0101] Example 30 Highly dispersed pellets of the hybrid catalyst of Production Example 10-1 were packed into a reaction tube with an inner diameter of 21 mm to prepare a methane production reactor. The obtained methane production reactor and methanation using the reactor were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0102] Example 31 A methane production reactor was produced in the same manner as in Example 30, except that the highly dispersed pellets of the hybrid catalyst of Production Example 10-2 were used instead of the highly dispersed pellets of the hybrid catalyst of Production Example 10-1. The obtained methane production reactor and methanation using this reactor were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0103] Comparative Example 1 A methane production reactor was produced in the same manner as in Example 30, except that the hybrid catalyst pellets of Production Example 9 were used instead of the highly dispersed hybrid catalyst pellets of Production Example 10-1. The obtained methane production reactor and methanation using the reactor were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0104]

[0105] <Evaluation> As is clear from Table 1, according to the examples of the present invention, by setting the dispersion ratio of the methanation reaction catalyst in the catalyst-containing portion to 0.60 or more, it is possible to significantly improve the methane yield.

[0106] The reactor according to the embodiment of the present invention can be suitably used in a process including two or more elementary reactions, an exothermic reaction and an endothermic reaction. In one embodiment, the reactor is a methane production reactor. The methane production reactor can be suitably used in methanation, which produces methane by reacting carbon dioxide with hydrogen, and can be particularly suitably used in ammonia methanation, which uses ammonia as a hydrogen source.

[0107] DESCRIPTION OF SYMBOLS 1 honeycomb substrate 12 partition wall 13 cell 14 gas flow channel 2 catalyst-containing layer 100 methane production reactor

Claims

1. A reactor used in a process involving two or more elementary reactions, namely, an exothermic reaction and an endothermic reaction, comprising: a gas flow path to which a raw material gas containing a first component and a second component is supplied; and a catalyst-containing section arranged to be able to come into contact with the raw material gas supplied to the gas flow path, wherein the catalyst-containing section contains: an endothermic reaction-promoting catalyst capable of promoting an endothermic reaction involving the first component; and an exothermic reaction-promoting catalyst capable of promoting an exothermic reaction between a reaction product of the first component and the second component, and wherein the dispersion ratio of the exothermic reaction-promoting catalyst calculated by cross-sectional analysis of the catalyst-containing section is 0.60 or greater.

2. The reactor of claim 1, wherein the dispersion ratio of the exothermic reaction-promoting catalyst is less than 0.

90.

3. A methane production reactor according to claim 1 or 2, wherein the first component is ammonia and the second component is carbon dioxide, the endothermic reaction-promoting catalyst is an ammonia decomposition catalyst capable of promoting a reaction that decomposes ammonia to produce hydrogen, and the exothermic reaction-promoting catalyst is a methanation reaction catalyst capable of promoting a reaction that produces methane from hydrogen and carbon dioxide.

4. The reactor according to claim 3, comprising a substrate defining the gas flow path, wherein the catalyst-containing portion is a catalyst-containing layer provided on a surface of the substrate so as to face the gas flow path.

5. The reactor according to claim 4, wherein the substrate is a honeycomb substrate having partition walls that define a plurality of cells, at least some of the plurality of cells include the gas flow channels, and the catalyst-containing layer is provided on the surface of the partition walls.

6. The reactor according to claim 5, wherein the substrate is made of ceramic.

7. The geometric surface area of ​​the substrate is 3.0 cm ２ / cm ３ ~50.0cm ２ / cm ３ 7. The reactor of claim 6, wherein 8. The reactor according to claim 3, wherein the methanation catalyst has an average secondary particle diameter of 0.1 μm to 20 μm, and the ammonia decomposition catalyst has an average secondary particle diameter of 0.1 μm to 100 μm.

9. The reactor of claim 3, wherein the ammonia decomposition catalyst has an active component comprising a transition metal.

10. The reactor of claim 9, wherein the transition metal comprises Co, Fe, Pt, Ru, Rh, Pd, Ni, Cu, Ag, Au, Ir, or a combination thereof.

11. The reactor of claim 10, wherein the transition metal comprises Ni, Ru, Co, or a combination thereof.

12. The reactor according to claim 9, wherein the ammonia decomposition catalyst further comprises a support for supporting the active component, and the support comprises aluminum oxide, titanium oxide, magnesium oxide, silicon oxide, yttrium oxide, zirconium oxide, or a composite oxide thereof, or calcium carbonate.

13. The reactor of claim 3, wherein the methanation catalyst has an active component comprising a transition metal.

14. The reactor of claim 13, wherein the transition metal comprises Co, Fe, Pt, Ru, Rh, Pd, Ni, Cu, Ag, Au, Ir, or a combination thereof.

15. The reactor of claim 14, wherein the transition metal comprises Ni, Ru, Co, or a combination thereof.

16. The reactor according to claim 13, wherein the methanation catalyst further comprises a support for supporting the active component, and the support comprises cerium oxide, silicon oxide, zirconium oxide, yttrium oxide, aluminum oxide, or a composite oxide thereof.

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