Methane production reactor

Abstract

Provided is a methane production reactor that exhibits excellent methane yield. A methane production reactor according to an embodiment of the present invention has gas flow paths to which a raw material gas containing ammonia and carbon dioxide is supplied. The methane production reactor comprises: a honeycomb-shaped base material including partition walls that define a plurality of cells, at least some of the plurality of cells including the gas flow paths; and catalyst-containing layers provided on the surfaces of the partition walls so as to face the gas flow paths, the catalyst-containing layers being capable of promoting a reaction for generating methane from the raw material gas.

Description

Methane Production Reactor

[0001] The present invention relates to a methane production reactor.

[0002] In recent years, from the perspective of reducing environmental impact, efforts 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 into 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 been investigated. Ammonia methanation involves a reaction in which ammonia is decomposed to produce hydrogen (an endothermic reaction) and a reaction in which the resulting hydrogen is reacted with carbon dioxide to produce methane (an exothermic reaction). For example, a technology using 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 have the problem of insufficient methane yield.

[0003] Japanese Patent Application Laid-Open No. 2015-196619

[0004] JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 2023, VOL. 56, NO. 1, 2248176

[0005] A primary object of the present invention is to provide a methane production reactor that provides an excellent methane yield.

[0006] [1] A methane production reactor according to an embodiment of the present invention is a methane production reactor having a gas flow path to which a raw material gas containing ammonia and carbon dioxide is supplied. The methane production reactor includes: a honeycomb substrate having partition walls that form a plurality of cells, at least some of the plurality of cells including the gas flow path; and a catalyst-containing layer provided on a surface of the partition wall so as to face the gas flow path, the catalyst-containing layer being capable of promoting a reaction to produce methane from the raw material gas. [2] In the above [1], the partition wall on which the catalyst-containing layer is provided has a geometric surface area of ​​3.0 cm ２ / cm ３[3] In the above [2], the geometric surface area of ​​the partition wall on which the catalyst-containing layer is provided is 10.0 cm ２ / cm ３ [4] In any one of the above [1] to [3], the geometric surface area of ​​the partition wall on which the catalyst-containing layer is provided is 50.0 cm ２ / cm ３[5] In any of [1] to [4] above, the substrate is made of ceramic. [6] In any of [1] to [5] above, the catalyst-containing layer includes an ammonia decomposition catalyst capable of promoting a reaction of decomposing ammonia to produce hydrogen; and a methanation reaction catalyst capable of promoting a reaction of producing methane from hydrogen and carbon dioxide. [7] In [6] above, 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. [8] In [6] or [7] above, the ammonia decomposition catalyst has an active component containing a transition metal. [9] In any of [6] to [8] above, the transition metal includes Co, Fe, Pt, Ru, Rh, Pd, Ni, Cu, Ag, Au, Ir, or a combination thereof.

[10] In the above [9], the transition metal includes Ni, Ru, Co, or a combination thereof.

[11] In any of the above [8] to

[10] , the ammonia decomposition catalyst further includes a support supporting the active component; the support includes aluminum oxide, titanium oxide, magnesium oxide, silicon oxide, yttrium oxide, zirconium oxide, cerium oxide, or a composite oxide thereof, or calcium carbonate.

[12] In any of the above [6] to

[11] , the methanation reaction catalyst has an active component including a transition metal.

[13] In any of the above [6] to

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

[14] In the above

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

[15] In any one of the above

[12] to

[14] , 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, titanium oxide, magnesium oxide, or a composite oxide thereof, or calcium carbonate.

[16] In any one of the above [1] to

[15] , the catalyst amount in the catalyst-containing layer is 50 g / L to 1200 g / L, and / or the thickness of the catalyst-containing layer is 600 μm or less.

[0007] According to an embodiment of the present invention, a methane production reactor with excellent methane yield can be realized.

[0008] 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.

[0009] 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.

[0010] A. Overview of the Methane Production Reactor The methane production reactor according to an embodiment of the present invention is a methane production reactor having a gas flow path to which a feed gas containing ammonia and carbon dioxide is supplied. The methane production reactor is typically used for ammonia methanation. Ammonia methanation involves two reactions: a reaction in which ammonia is decomposed to produce hydrogen using ammonia as a hydrogen source, and a reaction in which the resulting hydrogen is reacted with carbon dioxide to produce methane. The methane production reactor according to an embodiment of the present invention can smoothly carry out these two reactions.

[0011] 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 layer 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 form 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.

[0012] The catalyst-containing layer 2 is provided on the surface of the partition wall 12 so as to face the gas flow path 14. The catalyst-containing layer 2 is capable of promoting a reaction for producing methane from a feed gas containing ammonia and carbon dioxide as described above. The catalyst-containing layer 2 typically includes an ammonia decomposition catalyst capable of promoting a reaction for producing hydrogen by decomposing ammonia, and a methanation reaction catalyst capable of promoting a reaction for producing methane from carbon dioxide and hydrogen produced by the ammonia decomposition. 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 producing a methane production reactor will be described later. According to such a formation method, a catalyst-containing layer having the above-described configuration can be formed.

[0013] In this embodiment of the present invention, the geometric surface area of ​​the septum 12 is 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 ３ More preferably, it is 30.0 cm or more. ２ / cm ３ The geometric surface area of ​​the partition is, for example, 50.0 cm ２ / cm ３ It can be less than, for example, 45.0 cm ２ / cm ３or less. If the geometric surface area of ​​the partition walls is within this range, when a raw material gas containing ammonia and carbon dioxide is passed through the gas flow path and supplied to the catalyst-containing layer, the ammonia can efficiently come into contact with the ammonia decomposition catalyst, and the chemical reaction shown in the following formula (1) can proceed smoothly. Furthermore, hydrogen and carbon dioxide, which are products of the reaction, can efficiently come into contact with the methanation reaction catalyst, and the chemical reaction shown in the following formula (2) can proceed smoothly. In other words, 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 achieved. The geometric surface area of ​​the partition walls in the methane production reactor can be controlled, for example, by adjusting the cell density of the honeycomb substrate and the average pore size and / or porosity in the partition walls. 8NH ３ →12H ２ +4N ２ ... (1) CO ２ +4H ２ →CH ４ +2H ２ O... (2)

[0014] B. Honeycomb Substrate The honeycomb substrate 1 typically has a flow-through honeycomb structure. The honeycomb substrate 1 may have any suitable 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 in the center in a cross section perpendicular to the longitudinal direction.

[0015] 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.

[0016] 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 700 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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).

[0023] 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.

[0024] 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.

[0025] 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.

[0026] C. Catalyst-Containing Layer As described above, the catalyst-containing layer 2 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 (typically the center portion) of the cross section of the cell 13 where the catalyst-containing layer 2 is not formed. 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 in the illustrated example, or may be formed on a part 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.

[0027] In the catalyst-containing layer 2, typically, an ammonia decomposition catalyst and / or a methanation catalyst is dispersed. For example, when the ammonia decomposition catalyst and the methanation catalyst are the same, one type of catalyst may be dispersed. The ammonia decomposition catalyst and the methanation catalyst may each have any appropriate shape. The ammonia decomposition catalyst and the methanation catalyst are typically in the form of particles. These catalyst particles may be aggregates formed by aggregating multiple particles. With this configuration, mesopores may be formed in the catalyst-containing layer 2.

[0028] In the catalyst-containing layer 2, the dispersion ratio of the methanation 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, for example, 0.80 or less, or, for example, 0.75 or less. This means that the ammonia decomposition catalyst and the methanation catalyst are dispersed with very high uniformity in the catalyst-containing layer. As a result, a very excellent methane yield can be realized due to a synergistic effect with the effect of setting the geometric surface area of ​​the partition walls within the above range. 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 cut in a predetermined direction through the catalyst-containing portion is obtained; and (ii) the obtained scanning electron microscope image is subjected to binarization analysis using brightness as a threshold value to obtain a binarized image. The threshold value for binarization is set using Otsu's binarization as a discriminant analysis method. In the binary image, the portion corresponding to the methanation catalyst may be a white region or a black region depending on the type of methanation catalyst, the combination of the methanation catalyst and the ammonia decomposition catalyst, etc.; (iii) from the obtained binary image, the total area of ​​the region showing the methanation 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 methanation 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.

[0029] When the ammonia decomposition catalyst and the methanation 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 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 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 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 catalyst particles differ as described above, uniform dispersion can be achieved. As a result, an excellent methane yield can be achieved.

[0030] 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.

[0031] 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, cerium oxide, or composite oxides thereof, or calcium carbonate.

[0032] 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.

[0033] 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.

[0034] 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, titanium oxide, magnesium oxide, or composite oxides thereof, or calcium carbonate.

[0035] 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.

[0036] The catalyst-containing layer 2 may contain an additive in addition to the ammonia decomposition catalyst and the methanation reaction catalyst.

[0037] 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.

[0038] 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.

[0039] The catalyst amount in the catalyst-containing layer 2 is preferably 50 g / L to 1200 g / L. The catalyst amount may be, for example, 100 g / L or more, or, for example, 200 g / L or more, or, for example, 300 g / L or more, or, for example, 400 g / L or more, or, for example, 500 g / L or more, or, for example, 800 g / L or more. On the other hand, the catalyst amount may be, for example, 1100 g / L or less, or, for example, 1000 g / L or less, or, for example, 800 g / L or less, or, for example, 600 g / L or less, or, for example, 500 g / L or less, or, for example, 400 g / L or less. The upper and lower limits of the catalyst amount can be appropriately combined depending on the purpose and the type of catalyst. For example, a catalyst amount of "400 g / L" may be either an upper limit or a lower limit. Therefore, the catalyst amount may be, for example, 100 g / L to 400 g / L, or may be, for example, 400 g / L to 1000 g / L. A high methane yield can be achieved by appropriately adjusting the catalyst type and the preferred range of catalyst amount. The catalyst amount refers to the total amount of ammonia decomposition catalyst and methanation reaction catalyst per unit volume of the reactor (including the volume of the gas flow path).

[0040] The thickness of the catalyst-containing layer 2 is preferably 600 μm or less. If the thickness of the catalyst-containing layer is within this range, it is less susceptible to adverse effects of gas diffusion, and as a result, a high methane yield can be achieved. The thickness of the catalyst-containing layer can be reduced by increasing the geometric surface area of ​​the partition walls of the honeycomb substrate. The thickness of the catalyst-containing layer may be, for example, 550 μm or less, or may be, for example, 500 μm or less, or may be, for example, 450 μm or less, or may be, for example, 400 μm or less, or may be, for example, 350 μm or less, or may be, for example, 300 μm or less. The thickness of the catalyst-containing layer may be, for example, 10 μm or more, or may be, for example, 15 μm or more.

[0041] 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.

[0042] 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.

[0043] D. 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] <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.

[0048] 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.

[0049] 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.

[0050] In this manner, ammonia decomposition catalyst particles are prepared.

[0051] <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.

[0052] The mixed solution of the carrier dispersion and the nickel salt solution is prepared as described for the ammonia decomposition catalyst particles.

[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, methanation reaction catalyst particles are prepared.

[0055] 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. Any appropriate solvent that does not dissolve the catalyst 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. 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] In this manner, the methane production reactor 100 including the honeycomb substrate 1 and the catalyst-containing layer 2 is manufactured.

[0060] E. Methane Production Method As described above, the methane production reactor 100 can be suitably used for ammonia methanation. 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.

[0061] 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.

[0062] 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.

[0063] In one embodiment, the source gas may contain a balance of nitrogen, argon, helium, or other rare gases.

[0064] The flow rate of the source gas may be any appropriate flow rate depending on the purpose.

[0065] 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.

[0066] According to an embodiment of the present invention, typically, the honeycomb substrate 1 of the methane production reactor 100 has a geometric surface area of ​​3.0 cm ２ / cm ３ Since the contact frequencies of ammonia with the ammonia decomposition catalyst and hydrogen and carbon dioxide with the methanation reaction catalyst are high, methane can be produced with an excellent methane yield.

[0067] The methane yield is preferably 45% or more, more preferably 47% or more, even more preferably 50% or more, particularly preferably 51% or more, and particularly preferably 52% or more. The higher the methane yield, the better, and its upper limit may be, for example, 80%, or 75%, or 70%, or 65%, or 60%.

[0068] 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.

[0069] <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. Furthermore, the cell density of the honeycomb substrate was 40 cpsi, and the geometric surface area of ​​the partition walls was 3.1 cm. ２ / cm ３ It was.

[0070] <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. Furthermore, the cell density of the honeycomb substrate was 200 cpsi, and the geometric surface area of ​​the partition walls was 8.4 cm. ２ / cm ３ It was.

[0071] <Manufacturing 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. Furthermore, the cell density of the honeycomb substrate is 300 cpsi, and the geometric surface area of ​​the partition walls is 10.8 cm ２ / cm ３ It was.

[0072] <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.

[0073] <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.

[0074] 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.

[0075] <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.

[0076] 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.

[0077] <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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] <Production Example 7-1: 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 resulted in a dispersion of cerium oxide particles. Nickel (II) nitrate hexahydrate was also dissolved in distilled water to obtain a nickel nitrate aqueous solution. Next, a nickel nitrate aqueous solution was added to the cerium oxide particle dispersion 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 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 reaction catalyst particles was 5.6 μm.

[0086] Production Example 7-2: Preparation of methanation catalyst particles Methanation catalyst particles were obtained in the same manner as in Production Example 7-1, 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 content of Ru 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.

[0087] <Production Example 8: 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 7-1 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.

[0088] Example 1 The ammonia decomposition catalyst particles obtained in Production Example 4-1 and the methanation reaction catalyst particles obtained in Production Example 7-1 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. The thickness of the catalyst-containing layer was 252 μm, and the catalyst amount in the catalyst-containing layer was 278 g / L. In this way, a methane production reactor equipped with a honeycomb substrate and a catalyst-containing layer as shown in FIGS. 1 and 2 was fabricated. The methane production reactor and the methane yield in methanation using the reactor were evaluated as follows. The results are shown in Table 1, along with the results of Examples 2 to 51 and Comparative Examples 1 and 2 described below.

[0089] <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 130 mL / min. As a result, the raw material gas passed through each gas flow path provided in the methane production reactor, and a 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 50.2%.

[0090] Example 2 A methane production reactor including a honeycomb substrate and a catalyst-containing layer as shown in Figures 1 and 2 was produced in the same manner as in Example 1, except that the cell density of the honeycomb substrate was set to 200 cpsi and the thickness of the catalyst-containing layer was set to 110 µm. The geometric surface area of ​​the partition walls was 9.2 cm ２ / cm ３ It was.

[0091] Examples 3 to 51 Methane production reactors equipped with a honeycomb substrate and a catalyst-containing layer as shown in FIGS. 1 and 2 were prepared in the same manner as in Example 1, except that the configuration of the honeycomb substrate (material, cell density, geometric surface area), the types and combinations of ammonia decomposition catalyst particles and methanation reaction catalyst particles, the thickness of the catalyst-containing layer, and the catalyst amount in the catalyst-containing layer were changed as shown in Table 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. As is clear from Table 1, some catalyst particles can be used for both ammonia decomposition and methanation reactions.

[0092] Comparative Examples 1 and 2 Pellets of the hybrid catalyst of Production Example 8 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. In Table 1, the column for "catalyst-containing layer thickness" for Comparative Examples 1 and 2 should be read as "catalyst-containing portion thickness."

[0093]

[0094] <Evaluation> As is clear from Table 1, according to the examples of the present invention in which a predetermined catalyst-containing layer is formed, it is possible to significantly improve the methane yield compared to the comparative examples in which no catalyst-containing layer is formed.

[0095] The methane production reactor according to the embodiment of the present invention can be suitably used for methanation to produce methane by reacting carbon dioxide with hydrogen, and can be particularly suitably used for ammonia methanation using ammonia as the hydrogen source.

[0096] 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 methane production reactor having a gas flow path through which a raw material gas containing ammonia and carbon dioxide is supplied, the reactor comprising: a honeycomb substrate having partition walls that form a plurality of cells, at least some of the plurality of cells including the gas flow path; and a catalyst-containing layer provided on a surface of the partition walls so as to face the gas flow path, the catalyst-containing layer being capable of promoting a reaction that produces methane from the raw material gas.

2. The geometric surface area of ​​the partition wall on which the catalyst-containing layer is provided is 3.0 cm ２ / cm ３ The methane production reactor according to claim 1 .

3. The geometric surface area of ​​the partition wall on which the catalyst-containing layer is provided is 10.0 cm ２ / cm ３ The methane production reactor according to claim 2 .

4. The geometric surface area of ​​the partition wall on which the catalyst-containing layer is provided is 50.0 cm ２ / cm ３ 4. The methane production reactor according to claim 1, wherein:

5. A methane production reactor according to any one of claims 1 to 3, wherein the substrate is made of ceramics.

6. The reactor for producing methane according to any one of claims 1 to 3, wherein the catalyst-containing layer comprises: an ammonia decomposition catalyst capable of promoting a reaction of decomposing ammonia to produce hydrogen; and a methanation reaction catalyst capable of promoting a reaction of producing methane from hydrogen and carbon dioxide.

7. The reactor for producing methane according to claim 6, 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.

8. The methane production reactor of claim 6, wherein the ammonia decomposition catalyst has an active component comprising a transition metal.

9. The methane production reactor of claim 8, wherein the transition metal comprises Co, Fe, Pt, Ru, Rh, Pd, Ni, Cu, Ag, Au, Ir, or a combination thereof.

10. The methane production reactor of claim 9, wherein the transition metal comprises Ni, Ru, Co, or a combination thereof.

11. The reactor for producing methane according to claim 8, 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, cerium oxide, or a composite oxide thereof, or calcium carbonate.

12. The methane production reactor according to claim 6, wherein the methanation catalyst has an active component containing a transition metal.

13. The methane production reactor of claim 12, wherein the transition metal comprises Co, Fe, Pt, Ru, Rh, Pd, Ni, Cu, Ag, Au, Ir, or a combination thereof.

14. The methane production reactor of claim 13, wherein the transition metal comprises Ni, Ru, Co, or a combination thereof.

15. The reactor for producing methane according to claim 12, 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, titanium oxide, magnesium oxide, or a composite oxide thereof, or calcium carbonate.

16. The reactor for producing methane according to any one of claims 1 to 3, wherein the amount of catalyst in the catalyst-containing layer is 50 g / L to 1200 g / L and / or the thickness of the catalyst-containing layer is 600 μm or less.

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