Honeycomb structure

Abstract

To provide a structure having an excellent ammonia adsorption rate.SOLUTION: A honeycomb structure comprising partition walls defining a plurality of through holes, wherein the partition walls have a metal cyano complex, and the honeycomb structure is used for ammonia adsorption.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a honeycomb structure. [Background technology]

[0002] Ammonia is a material that is attracting attention for its important management, particularly in the fields of the environment and energy. In the energy field, methods are being considered for synthesizing ammonia using renewable energy, storing it as chemical energy, and then using it as fuel as needed, or extracting hydrogen and using it as fuel. Ammonia is also known to be a cause of odors in toilets and other real-world environments, and methods for deodorizing by adsorbing and removing ammonia are being investigated.

[0003] In order to manage ammonia, an ammonia adsorbent is required, and for example, Patent Document 1 discloses an ammonia adsorbent containing a metal cyano complex as an active ingredient. Furthermore, Patent Document 2 discloses a pellet-shaped ammonia adsorbent composed of an adsorption base material containing a metal cyano complex and a binder.

[0004] Patent Document 3 discloses a pollutant removal member in which a pollutant removing agent containing a metal cyano complex is supported on a support having a honeycomb structure, but the pollutant to be removed is not ammonia. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6345774 [Patent Document 2] Patent No. 7115944 [Patent Document 3] Patent No. 7486148 Summary of the Invention [Problem to be solved by the invention]

[0006] The adsorbents disclosed in Patent Documents 1 and 2 have a problem in that they have a slow ammonia adsorption rate.

[0007] The present invention has been made in view of the above problems, and has an object to provide a structure that is excellent in the rate of adsorption of ammonia. [Means for solving the problem]

[0008] The honeycomb structure of the present invention includes partition walls that define a plurality of through-holes, the partition walls having a metal cyano complex, and is used for ammonia adsorption.

[0009] Metal cyano complexes have the ability to adsorb ammonia, and honeycomb structures whose partition walls have metal cyano complexes have a large geometric surface area (GSA), which increases the reaction rate between ammonia in the medium and the metal cyano complexes. This results in an excellent ammonia adsorption rate and enables efficient ammonia adsorption.

[0010] In the honeycomb structure of the present invention, the metal cyano complex has a main composition represented by the general formula: A x M[M'(CN)6] y zH2O It is preferable that the formula be: [In the formula, M represents one or more metal atoms selected from the group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadolinium, lutetium, barium, strontium, and calcium; M' represents one or more metal atoms selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper; A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, rubidium, and cesium; x represents a number from 0 to 3, y represents a number from 0.1 to 1.5, and z represents a number from 0 to 6.]

[0011] In the honeycomb structure of the present invention, the metal cyano complex has a main composition represented by the general formula: K 2 / 11 Cu[Fe(II)(CN)6] 6 / 11 ·zH2O is preferred.

[0012] The weight ratio of the metal cyano complex contained in the honeycomb structure of the present invention is preferably 50% by weight or more. When the weight ratio of the metal cyano complex contained in the honeycomb structure is 50% by weight or more, the amount of the metal cyano complex is sufficiently large, so that the ammonia adsorption rate and the amount of ammonia adsorption can be increased.

[0013] In the honeycomb structure of the present invention, the partition walls preferably contain the metal cyano complex. A honeycomb structure containing a metal cyano complex in the partition walls can adsorb ammonia to the partition walls themselves, and therefore has many ammonia adsorption sites, making it possible to increase the amount of ammonia adsorbed.

[0014] In the honeycomb structure of the present invention, it is preferable that the partition walls further contain a binder and a shape retaining agent.

[0015] In the honeycomb structure of the present invention, the metal cyano complex is preferably supported on the surface of the partition wall. In a honeycomb structure in which a metal cyano complex is supported on the surface of the partition walls, ammonia is adsorbed by the metal cyano complex on the surface of the partition walls. Even in this case, the large geometric surface area (GSA) of the honeycomb structure can be utilized to increase the reaction rate between ammonia in the medium and the metal cyano complex. This results in an excellent ammonia adsorption rate and enables efficient ammonia adsorption. Furthermore, the amount of expensive metal cyano complexes used can be reduced.

[0016] In the honeycomb structure of the present invention, the partition walls preferably contain at least one selected from the group consisting of zeolite, cordierite, silicon carbide, alumina, titanium oxide, zirconia, silicon nitride, aluminum nitride, and carbon. These materials are resistant to corrosion by ammonia and can be suitably used as materials for forming the partition walls of honeycomb structures used for ammonia adsorption. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a honeycomb structure. [Figure 2] FIG. 2 is a perspective view schematically showing an example of another shape of the honeycomb structure. [Figure 3] FIG. 3 is a perspective view schematically showing an example of another shape of the honeycomb structure. [Figure 4] FIG. 4 is a perspective view schematically showing an example of another shape of the honeycomb structure. [Figure 5] FIG. 5 is a schematic diagram of an evaluation device for the amount of ammonia adsorption and the rate of ammonia adsorption. [Figure 6] FIG. 6 is a graph in which the horizontal axis represents the aeration time and the vertical axis represents the ammonia concentration at the adsorbent outlet. [Figure 7] FIG. 7 is a graph showing the pore size distribution of the honeycomb structure obtained in Example 1 and the granules of Comparative Example 1.

[0018] (Detailed Description of the Invention) The honeycomb structure of the present invention will be specifically described below. However, the present invention is not limited to the following configuration, and can be appropriately modified and applied within the scope that does not change the gist of the present invention. Note that a combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0019] The honeycomb structure of the present invention includes partition walls that define a plurality of through-holes, the partition walls having a metal cyano complex, and is used for ammonia adsorption. In this specification, the term "ammonia" to be adsorbed refers to ammonia molecules (NH3) and ammonium ions (NH4 + ) and will be written as "ammonia" to include either or both of the ammonia molecule and the ammonium ion.

[0020] First, examples of the shape of the honeycomb structure will be described. The honeycomb structure has a plurality of through holes defined by partition walls extending in the longitudinal direction, and has a shape that allows a medium (gas or liquid) containing ammonia to flow through the through holes. The term "longitudinal direction" refers to the direction in which the through holes extend, and does not necessarily correspond to the direction in which the dimensions of the honeycomb structure become longer.

[0021] FIG. 1 is a perspective view schematically showing an example of a honeycomb structure. In the honeycomb structure 1 shown in FIG. 1, a plurality of through holes defined by the partition walls 20 extend in the longitudinal direction (the direction indicated by the double-headed arrow L in FIG. 1). The medium flows into the through holes 10 from the inlet end face 31 of the honeycomb structure 1 and flows out from the outlet end face 32. When the medium passes through the through holes 10, ammonia in the medium is adsorbed by the metal cyano complex contained in the partition walls 20.

[0022] The shape of the honeycomb structure is not particularly limited, but is preferably cylindrical, and may be a rectangular pillar, an elliptical pillar, an oblong pillar, a rectangular pillar with rounded edges (for example, a triangular pillar or a square pillar with rounded edges), etc. The honeycomb structure 1 shown in FIG. 1 has a cylindrical shape.

[0023] When the honeycomb structure has a cylindrical shape, its dimensions are not particularly limited, but it is preferable that the diameter of the end face (bottom face of the cylinder) is 10 to 300 mm and the length in the longitudinal direction is 10 to 300 mm.

[0024] The shape of the through hole (the shape of the end face of the through hole) is not particularly limited, and can be polygonal, circular, etc. When the through hole is polygonal, it can be triangular, quadrilateral (rectangle, square, rhombus, trapezoid, etc.), pentagonal, hexagonal, octagonal, etc. Furthermore, a plurality of types of through holes with different shapes and sizes may be combined. The shape and size of the through holes may be different between the central portion and the peripheral portion of the end face of the honeycomb structure. The through holes 10 in the honeycomb structure 1 shown in Fig. 1 are all square with the same dimensions. At the outermost periphery of the honeycomb structure, the shape of the through holes is adjusted to fit the shape of the outer periphery of the honeycomb structure.

[0025] The density of the through holes (also called cell density) on the end face of the honeycomb structure is not particularly limited, but is preferably 31 to 155 holes / cm. 2 (200~1000 pieces / inch 2 ) is preferred.

[0026] The opening ratio at the end face of the honeycomb structure is not particularly limited, but is preferably 30 to 70%. The opening ratio of a honeycomb structure means the ratio of the area of ​​spaces resulting from a plurality of through holes to the cross-sectional area of ​​the honeycomb structure in a cross section perpendicular to the longitudinal direction of the honeycomb structure.

[0027] The preferred geometric surface area (also referred to as "GSA") of the honeycomb structure is not particularly limited, but is preferably 20 to 45 cm 2 / cm 3 It is preferable that: The geometric surface area means a value obtained by dividing the total value of the external surface area of ​​the partition walls of the honeycomb structure by the volume of the honeycomb structure. The geometric surface area and opening ratio of the honeycomb structure can be adjusted by changing the shape, density, arrangement, etc. of the through holes of the honeycomb structure.

[0028] The partition wall may be made of a dense or porous body. When the partition walls are dense, the partition walls have excellent strength. When the partition walls are porous, the true surface area of ​​the partition walls of the honeycomb structure increases, and the number of adsorption sites for ammonia further increases, allowing the amount of ammonia adsorbed to be further increased.When the partition walls are porous, the porosity is preferably 20 to 60%. The porosity of the partition walls can be measured by mercury porosimetry (in accordance with JIS R1655:2003). It is also desirable that pores have a pore diameter in the range of 0.05 to 10 μm. This is because ammonia gas comes into contact with the interior of the partition walls, increasing the amount of ammonia adsorbed. The pore diameter can be measured by mercury intrusion porosimetry (in accordance with JIS R1655:2003).

[0029] The BET specific surface area of ​​the partition walls of the honeycomb structure is not particularly limited. When the partition walls are porous, the BET specific surface area is 100 m 2 The BET specific surface area of ​​the partition walls of the honeycomb structure is preferably 100 to 1000 m / g or more. 2 / g, and more preferably 150 to 600m 2 / g is more preferred. The BET specific surface area means the surface area per unit weight of the partition walls measured by N2 adsorption using the BET method. The BET specific surface area is measured based on JIS Z8830:2013, a method for measuring the specific surface area of ​​powders (solids) by gas adsorption. The BET specific surface area and porosity of the partition walls can be adjusted by changing the type and composition of the material constituting the partition walls of the honeycomb structure.

[0030] The thickness of the partition walls is not particularly limited, but is preferably 0.10 to 0.46 mm. The density of the partition wall is 1.0 to 2.0 g / cm 3 It is preferable that:

[0031] 2, 3 and 4 are perspective views schematically showing examples of other shapes of honeycomb structures. 2 differs from the honeycomb structure 1 shown in FIG 1 in the shape of the through holes (through holes 11). The other configuration is the same as that of the honeycomb structure 1 shown in FIG 1. The through holes 11 in the honeycomb structure 2 are all shaped like regular hexagons with the same dimensions. At the outermost periphery of the honeycomb structure, the shape of the through holes is adjusted to match the shape of the outer periphery of the honeycomb structure.

[0032] The honeycomb structure 3 shown in Fig. 3 differs from the honeycomb structure 1 shown in Fig. 1 in the shape of the through holes (through holes 12 and 13), and the shape of the through holes is a combination of regular octagonal through holes 12 and square through holes 13. The other configurations are the same as those of the honeycomb structure 1 shown in Fig. 1.

[0033] Through hole 12 is a large through hole having a larger cross-sectional area than through hole 13, and through hole 13 is a small through hole having a smaller cross-sectional area than through hole 13. That is, the honeycomb structure 3 shown in FIG. 3 is an example of a configuration in which a plurality of types of through holes having different shapes and sizes are combined. At the outermost periphery of the honeycomb structure, the shape of the through holes is adjusted to match the shape of the outer periphery of the honeycomb structure.

[0034] The honeycomb structure 4 shown in FIG. 4 is a prismatic (quadratic) honeycomb structure. When the honeycomb structure has a rectangular pillar shape, its dimensions are not particularly limited, but it is preferable that the length and width of the end face (bottom face of the rectangular pillar) are each 10 to 300 mm, and the length in the longitudinal direction is 10 to 300 mm. The through holes 10 are all square in shape and have the same dimensions. Other configurations are the same as those of the honeycomb structure 1 shown in FIG.

[0035] Next, the metal cyano complex contained in the partition wall will be described. Metal cyano complexes are substances that have the function of adsorbing ammonia and / or ammonium ions. In this specification, the term "the partition wall has a metal cyano complex" means that the partition wall contains a metal cyano complex, or the partition wall supports a metal cyano complex on its surface, or both of these.

[0036] As the metal cyano complex, it is preferable to use a Prussian blue complex. Prussian blue complexes have a three-dimensional structure in which iron ions (Fe) and iron hexacyanoate ions [Fe(CN)6] are connected, and they contain tiny spaces (void sites) of approximately 0.5 nm inside, which can take up ammonia molecules or ammonium ions.

[0037] Furthermore, by replacing the iron ion with another metal ion, it is possible to create a defect in which the iron hexacyanoate ion [Fe(CN)6] is missing, and ammonia molecules or ammonium ions can be adsorbed onto the exposed metal ion (coordination site) in this defect.

[0038] The metal cyano complex is preferably a substance whose main composition is represented by the following general formula: A x M[M'(CN)6] y zH2O [In the formula, M represents one or more metal atoms selected from the group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadolinium, lutetium, barium, strontium, and calcium; M' represents one or more metal atoms selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper; A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, rubidium, and cesium; x represents a number from 0 to 3, y represents a number from 0.1 to 1.5, and z represents a number from 0 to 6.]

[0039] The crystal structure of a metal cyano complex is generally a face-centered cubic structure, but is not particularly limited. For example, K 0.67 Zn[Fe(CN)6] 0.67 ·zH2O forms a hexagonal crystal.

[0040] x is preferably 0 to 3, more preferably 0 to 2.5, and particularly preferably 0 to 2. y is preferably 0.1 to 1.5, more preferably 0.4 to 1.3, and particularly preferably 0.5 to 1. z is preferably 0 to 6, more preferably 0.5 to 5.5, and particularly preferably 1 to 5. However, if x, y, and z contain salts as impurities or if the material contains water that is not incorporated into the internal structure of the Prussian blue-type complex, the effects of these must be removed before evaluation.

[0041] However, NH3 and NH4 + The preferred range of the value of y, in particular, varies depending on which of the two is considered to be the main target for adsorption. A small y means that there is little [M'(CN)6] in the crystal, and in this case, the metal M is present in excess compared to [M'(CN)6]. In this case, a structure is formed that makes it easy for ligands to adsorb around the metal M, and the amount of adsorption of NH3 in particular increases.

[0042] In addition, the general formula, A x M[M'(CN)6]y In zH2O, when M' is Fe and M is identified, it is called an M-iron cyanide complex. Examples of metal cyanide complexes using this designation include iron-iron cyanide complexes (M is Fe, M' is Fe), copper-iron cyanide complexes (M is Cu, M' is Fe), zinc-iron cyanide complexes (M is Zn, M' is Fe), manganese-iron cyanide complexes (M is Mn, M' is Fe), cobalt-iron cyanide complexes (M is Co, M' is Fe), and nickel-iron cyanide complexes (M is Ni, M' is Fe). The copper-iron cyano complex is preferably a copper-iron (II) cyano complex.

[0043] Specific examples of metal cyano complexes include the following: (In the chemical formula below, z represents a number from 0 to 6.) K 0.68 Cu[Fe(CN)6] 0.65 3.17H2O K 0.47 Cu[Fe(CN)6] 0.61 3.80H2O K 0.34 Cu[Fe(CN)6] 0.57 3.98H2O K 0.06 Cu[Fe(CN)6] 0.52 4.55H2O Mn[Fe(CN)6] 0.67 4.0H2O Fe4[Fe(CN)6]3·zH2O K 0.23 Fe[Fe(CN)6] 0.74 3.5H2O Co[Co(CN)6] 0.60 zH2O Cu[Co(CN)6] 0.50 zH2O K 2 / 11 Cu[Fe(II)(CN)6] 6 / 11 zH2O

[0044] As for the particle size of the metal cyano complex, generally speaking, the adsorption rate is often faster as the specific surface area of ​​the material increases. From this perspective, it is preferable for the particles to have an average primary particle size of 500 nm or less, more preferably 300 nm or less, and particularly preferably 100 nm or less. There is no particular lower limit to the particle size, but it is practical to set the particle size to 4 nm or more. In the present invention, the primary particle diameter refers to the diameter of a primary particle, and is determined by measuring the diameters of 10 primary particles randomly selected from a 500,000x magnification field of view using a scanning electron microscope, and averaging these diameters to determine the primary particle diameter. In some cases, ligands or the like are adsorbed on the particle surface, and in such cases, the primary particle size refers to the particle size excluding the ligands.

[0045] The synthesis (preparation) method of the metal cyano complex is not particularly limited as long as it can synthesize the desired composition. One method is to mix an aqueous solution containing ions of the metal M in the general formula above with an aqueous solution containing iron hexacyano ions, and obtain the metal cyano complex as a precipitate. However, even if the raw materials are mixed in the desired composition ratio, the desired composition and ammonia (and / or ammonium ion) adsorption amount may not be achieved. In this case, the ammonia adsorption amount can be increased by increasing the molar ratio of iron hexacyano ions to the metal M (referred to as the Fe / M ratio). In this case, considering y in the general formula above, the composition y of the metal cyano complex is 1 or less, but it is preferable to set the Fe / M ratio to 1 or greater during synthesis. Although there is no upper limit to the Fe / M ratio, the higher the Fe / M ratio, the higher the cost becomes, so it is preferable that the Fe / M ratio is not too high, and the Fe:M ratio is preferably 1:1 to 1:50.

[0046] The weight ratio of the metal cyano complex contained in the honeycomb structure is preferably 50% by weight or more. When the weight ratio of the metal cyano complex is 50% by weight or more, the amount of the metal cyano complex is sufficiently large, so that the ammonia adsorption rate and the ammonia adsorption amount can be increased.

[0047] In the honeycomb structure of the present invention, it is preferable that a metal cyano complex is contained in the partition walls. By containing a metal cyano complex in the partition wall, the partition wall itself can have an ammonia adsorption ability.

[0048] Hereinafter, an embodiment in which a metal cyano complex is contained in the partition walls of a honeycomb structure will be described. A honeycomb structure containing a metal cyano complex in the partition walls can be obtained by forming a composition containing a metal cyano complex into the shape of the honeycomb structure.

[0049] The partition wall preferably contains a binder and a shape retainer in addition to the metal cyano complex. Examples of binders include methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol, phenolic resins, epoxy resins, etc. These may be used alone or in combination of two or more.

[0050] Examples of the shape retaining agent include alumina sol, silica sol, titania sol, water glass, sepiolite, attapulgite, bentonite, and boehmite. These may be used alone or in combination of two or more.

[0051] When the partition wall contains a binder and a shape retainer in addition to the metal cyano complex, the metal cyano complex is solidified by the binder and the shape retainer to form a structural material whose shape is fixed.

[0052] The partition walls may contain other components such as inorganic particles other than the metal cyano complex, inorganic fibers, a molding aid, a plasticizer, a dispersant, and a lubricant.

[0053] Examples of inorganic particles other than metal cyano complexes include particles of zeolite, cordierite, silicon carbide, alumina, titanium oxide, zirconia, silicon nitride, aluminum nitride, and carbon (activated carbon). The partition walls may contain a material capable of adsorbing ammonia, such as zeolite or activated carbon.

[0054] Furthermore, examples of zeolites include, but are not limited to, LTA type, FER type, MWW type, MFI type, MOR type, LTL type, FAU type, BEA type, DDR type, CHA type, and AFI type.

[0055] Examples of inorganic fibers include silica-alumina fibers, mullite fibers, silica fibers, alumina fibers, zirconia fibers, glass fibers, etc. These may be used alone or in combination of two or more. By blending inorganic fibers, the strength of the partition walls can be improved.

[0056] Examples of the molding aid include ethylene glycol, dextrin, fatty acids, fatty acid soaps, and polyalcohols. Examples of the plasticizer include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether. Dispersants include, for example, sorbitan fatty acid esters. An example of the lubricant is glycerin.

[0057] In addition, when the partition walls are made porous, a pore-forming agent such as balloons, which are micro-hollow spheres containing an oxide ceramic, organic particles, graphite, etc. may be added as necessary. As the organic particles, spherical acrylic particles, spherical polyvinyl alcohol particles, starch particles, etc. can be used. The balloons are not particularly limited, and examples thereof include alumina balloons, glass microballoons, shirasu balloons, fly ash balloons (FA balloons), mullite balloons, etc. Among these, alumina balloons are preferred.

[0058] When a metal cyano complex is contained in the partition wall, the content of the metal cyano complex in the partition wall is preferably 50% by weight or more, more preferably 80% by weight or more, and is preferably 95% by weight or less. By increasing the amount of the metal cyano complex in the partition wall, the ammonia adsorption rate and the amount of ammonia adsorbed can be increased.

[0059] The content of the metal cyano complex component contained in the partition wall is preferably in the following proportions. Binder: 1 to 15% by weight Forming agent: 0 to 5% by weight Inorganic particles other than metal cyano complexes: 0 to 40% by weight Inorganic fibers: 0 to 10% by weight Molding aid: 0 to 5% by weight Plasticizer: 0 to 5% by weight Dispersant: 0 to 45% by weight Lubricant: 0 to 5% by weight

[0060] In the honeycomb structure of the present invention, the metal cyano complex is preferably supported on the surface of the partition wall. By supporting a metal cyano complex on the surface of the partition walls, the surface of the partition walls can have ammonia adsorption ability. In this case, the large geometric surface area (GSA) of the honeycomb structure can be utilized to increase the reaction rate between ammonia in the medium and the metal cyano complex. This results in an excellent ammonia adsorption rate and enables efficient ammonia adsorption. Furthermore, the amount of expensive metal cyano complexes used can be reduced.

[0061] Hereinafter, the mode in which a metal cyano complex is supported on the surface of the partition walls of the honeycomb structure will be described. In this case, the material forming the partition wall does not need to contain a metal cyano complex. The material for forming the partition wall is not particularly limited, but examples thereof include metal materials, non-metal materials, and organic materials.

[0062] Among these, non-metallic materials (inorganic materials other than metallic materials) are preferred, and the main component of the material constituting the partition walls preferably contains at least one selected from the group consisting of zeolite, cordierite, silicon carbide, alumina, titanium oxide, zirconia, silicon nitride, aluminum nitride, and carbon. When the partition walls are made of a non-metallic material, they are resistant to corrosion by ammonia and can be suitably used as a material for forming the partition walls of a honeycomb structure used for ammonia adsorption.

[0063] Examples of zeolites include, but are not limited to, LTA type, FER type, MWW type, MFI type, MOR type, LTL type, FAU type, BEA type, DDR type, CHA type, and AFI type.

[0064] The partition walls not containing a metal cyano complex may contain the components that may be contained in the partition wall, such as a binder, a shape retaining agent, inorganic fibers, a molding aid, a plasticizer, a dispersant, and a lubricant, which are described in the embodiment in which the partition walls contain a metal cyano complex.

[0065] A honeycomb structure in which the partition walls do not contain a metal cyano complex is obtained by forming a composition that does not contain a metal cyano complex into the shape of a honeycomb structure. Also, a known honeycomb structure that does not contain a metal cyano complex may be used.

[0066] A slurry containing a metal cyano complex is prepared, a honeycomb structure is immersed in the slurry, and then dried, thereby supporting the metal cyano complex on the partition walls of the honeycomb structure, thereby obtaining a honeycomb structure in which the metal cyano complex is supported on the surfaces of the partition walls.

[0067] Alternatively, a solution containing a metal cyano complex may be prepared, droplets of the solution may be dispersed in a carrier gas by spraying, and then dried to obtain a carrier gas in which the metal cyano complex powder is dispersed. The carrier gas in which the metal cyano complex powder is dispersed may then be flowed into the through holes of the honeycomb structure to support the metal cyano complex on the surface of the partition wall.

[0068] Alternatively, particles with a large specific surface area, such as silica or γ-alumina, may be supported on the partition walls of a honeycomb structure as a support material, and a metal cyano complex may be supported on the support material, thereby increasing the surface area of ​​the portion where the metal cyano complex is supported and improving the dispersibility of the metal cyano complex. Furthermore, when a support material is used, a metal cyano complex may be attached to the support material, and the support material to which the metal cyano complex is attached may be supported on the honeycomb structure.

[0069] The amount of the metal cyano complex supported is not particularly limited, but is preferably 10 to 150 g / L, and more preferably 50 to 100 g / L. In this specification, the amount of the metal cyano complex supported refers to the weight of the metal cyano complex other than the metal cyano complex contained in the partition walls themselves, out of the weight of the metal cyano complex per apparent volume of the honeycomb structure. Note that the apparent volume of the honeycomb structure includes the volume of the through holes.

[0070] Furthermore, in a honeycomb structure in which a metal cyano complex is contained in the partition walls, a metal cyano complex may be further supported on the surface of the partition walls. In this case, the effects of both ammonia adsorption by the metal cyano complex contained in the partition wall and ammonia adsorption by the metal cyano complex supported on the surface of the partition wall are exerted, so that the ammonia adsorption rate and the ammonia adsorption amount can be further increased.

[0071] The honeycomb structure of the present invention is used for ammonia adsorption. From the perspective of carbon neutrality, the use of ammonia itself as fuel or the generation of hydrogen from ammonia and the use of that hydrogen as fuel are being considered, and as a result, ammonia consumption is expected to increase. However, research into planetary boundaries has pointed out problems with the circulation of nitrogen, and so, if it can be recovered as ammonia, it is considered preferable to recover and reuse the nitrogen atoms contained in ammonia as ammonia without converting them to N2. The honeycomb structure of the present invention can be used as an adsorption carrier specialized for adsorbing ammonia, which meets such demands.

[0072] The ammonia-containing medium to be passed through the honeycomb structure may be a gas or a liquid. Examples of gases containing ammonia include exhaust gases from factories, livestock facilities, agricultural facilities, sewage treatment facilities, wastewater treatment facilities, and waste disposal facilities. Examples of liquids that contain ammonia (ammonium ions) include wastewater from factories, livestock facilities, agricultural facilities, sewage treatment facilities, wastewater treatment facilities, and waste disposal facilities.

[0073] When a gas is passed through the honeycomb structure, the flow rate of the gas is preferably 0.1 to 10 L / min, and the space velocity is preferably 2000 to 50000 (1 / h).

[0074] By desorbing the ammonia adsorbed in the honeycomb structure and storing the ammonia in an ammonia storage container such as an ammonia cylinder, the honeycomb structure can be regenerated and used as a honeycomb structure for adsorbing ammonia again. Ammonia can be desorbed from the honeycomb structure by heating the honeycomb structure. In this case, the heating temperature is preferably 80° C. or higher and 120° C. or lower. Methods for desorbing ammonia by methods other than heating include placing the honeycomb structure with adsorbed ammonia under reduced pressure to desorb the ammonia from the honeycomb structure, or washing the honeycomb structure with adsorbed ammonia with or immersing it in an aqueous solvent to dissolve the ammonia into the aqueous solvent. Furthermore, from the viewpoint of preventing the ammonia adsorbed in the honeycomb structure from being unintentionally desorbed, it is preferable that the adsorption of ammonia into the honeycomb structure be carried out in an environment of 60° C. or less.

[0075] The amount of ammonia that can be adsorbed per unit weight of the honeycomb structure is preferably 1 mol / kg or more, and more preferably 2 mol / kg or more. The ammonia adsorption rate per unit weight per unit time of the honeycomb structure is preferably 0.6 mol / kg·h or more, and more preferably 1.0 mol / kg·h or more. The amount of ammonia adsorbed and the rate of ammonia adsorption of the honeycomb structure can be measured by the procedure described in the examples below.

[0076] When the honeycomb structure is used as an adsorbent for adsorbing ammonia, only one honeycomb structure may be used, or a plurality of honeycomb structures may be used in combination. When a plurality of honeycomb structures are used, the honeycomb structures may be arranged in series so that the through holes of the honeycomb structures are continuous, or the honeycomb structures may be arranged in parallel so that the area of ​​the end faces is large. Alternatively, an aggregated honeycomb structure may be formed by combining the side surfaces of rectangular pillar-shaped honeycomb structures with an adhesive or the like.

[0077] Hereinafter, as a method for manufacturing a honeycomb structure of the present invention, an example of a method for manufacturing a honeycomb structure having a configuration in which a metal cyano complex is contained in the partition walls will be described. The honeycomb structure can be manufactured by preparing a raw material composition containing a metal cyano complex, extruding the raw material composition to obtain a honeycomb formed body, and drying the honeycomb formed body.

[0078] First, a raw material composition containing a metal cyano complex is prepared. The raw material composition may be a wet slurry mixture containing a metal cyano complex and capable of being extruded. The raw material composition preferably contains a binder and a shape-retaining agent. Furthermore, the partition walls may contain the above-mentioned inorganic fibers, molding aids, plasticizers, dispersants, lubricants, pore-forming agents, and the like.

[0079] Next, the raw material composition is charged into an extrusion molding machine and extrusion-molded to produce a honeycomb molded body of a predetermined shape. In this case, a mold may be used to produce a honeycomb formed body that has a cross-sectional shape having the through-hole structure (shape and arrangement of the through-holes) shown in any one of FIGS.

[0080] The honeycomb molded body is cut to a predetermined length and dried using an electric dryer, microwave dryer, hot air dryer, dielectric dryer, reduced pressure dryer, vacuum dryer, freeze dryer or the like. When an electric dryer is used, the drying conditions are preferably 35 to 60°C and 12 to 120 hours. The pore size in the honeycomb formed body can be adjusted by appropriately changing the freeze-drying conditions. A honeycomb structure can be manufactured by the above procedure.

[0081] Furthermore, a metal cyano complex may be supported on the surface of the partition walls of the produced honeycomb structure. As a method for supporting the metal cyano complex on the surface of the partition walls of the honeycomb structure, the method described in the section "Mode in which the metal cyano complex is supported on the surface of the partition walls of the honeycomb structure" can be used.

[0082] The present specification discloses the following:

[0083] The present disclosure (1) provides a honeycomb structure having partition walls that define a plurality of through holes, the partition walls containing a metal cyano complex, and used for ammonia adsorption.

[0084] The present disclosure (2) provides that the metal cyano complex has a main composition represented by the general formula: A x M[M'(CN)6] y zH2O The honeycomb structure according to the present disclosure (1) is shown in FIG. [In the formula, M represents one or more metal atoms selected from the group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadolinium, lutetium, barium, strontium, and calcium; M' represents one or more metal atoms selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper; A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, rubidium, and cesium; x represents a number from 0 to 3, y represents a number from 0.1 to 1.5, and z represents a number from 0 to 6.]

[0085] The present disclosure (3) provides that the metal cyano complex has a main composition represented by the general formula: K 2 / 11 Cu[Fe(II)(CN)6] 6 / 11 The honeycomb structure according to the present disclosure (2), wherein the temperature is 0.05 to 1.05° C. or less.

[0086] The present disclosure (4) is the honeycomb structure according to any one of the present disclosures (1) to (3), wherein the weight ratio of the metal cyano complex contained in the honeycomb structure is 50% by weight or more.

[0087] The present disclosure (5) is the honeycomb structure according to any one of the present disclosures (1) to (4), wherein the partition walls contain the metal cyano complex.

[0088] The present disclosure (6) is the honeycomb structure according to the present disclosure (5), wherein the partition walls further contain a binder and a shape retaining agent.

[0089] The present disclosure (7) is the honeycomb structure according to any one of the present disclosures (1) to (6), wherein the metal cyano complex is supported on the surface of the partition wall.

[0090] The present disclosure (8) is the honeycomb structure according to any one of the present disclosures (1) to (7), wherein the partition walls contain at least one selected from the group consisting of zeolite, cordierite, silicon carbide, alumina, titanium oxide, zirconia, silicon nitride, aluminum nitride, and carbon. [Example]

[0091] EXAMPLES Hereinafter, examples will be given that more specifically disclose the present invention, but the present invention is not limited to these examples.

[0092] Example 1 Pellet pellets of Prussian blue complex (cylindrical, average diameter 2 mm x length 7 mm) manufactured by Nanoblue Co., Ltd. were prepared as granular metal cyano complexes, and were pulverized using a jet mill to a D50 of 10 μm to obtain a powder of Prussian blue complex. The composition of the Prussian blue complex is K, represented by casNo: 126870-04-0. 2 / 11 Cu[Fe(II)(CN)6] 6 / 11 The composition is zH2O (z is a number between 0 and 6).

[0093] 53 parts by weight of Prussian blue complex powder, 5 parts by weight of celluloses (methyl cellulose and hydroxyethyl methyl cellulose) as binders, 5 parts by weight of bentonite as a shape retainer, and 37 parts by weight of water as a dispersant were mixed and kneaded to obtain a wet mixture. The wet mixture was extruded using an extruder to form a honeycomb molded body, which was then cooled to −30° C. in a freezer, and then dried by reducing the pressure to 10 Pa using a vacuum dryer. The honeycomb structure produced in Example 1 had a diameter of 20 mm and a length of 24 mm (apparent volume 25 cm 3 ) and the thickness of the partition wall is 0.24 mm (9.6 mil), and the density of the through holes is 62 / cm 2 (397 pieces / inch 2 ) was. The geometric surface area (GSA) of the honeycomb structure is 25.4 cm 2 / cm3 It was.

[0094] The honeycomb structure was placed in a container of the same size as the honeycomb structure, and a test gas, a mixture of 1000 ppm ammonia and nitrogen, was passed through the honeycomb structure at a flow rate of 3.8 L / min (space velocity 30,000 (1 / h)). The calculated pressure loss during the flow was 3.9 Pa.

[0095] (Comparative Example 1) As the metal cyano complex, pellets of the Prussian blue complex manufactured by Nanoblue Co., Ltd. prepared in Example 1 were used in the form of granules without being crushed or molded. The pellets were packed into a quartz column with a diameter of 22.3 mm. The packed amount was 7 g, and the total volume of the packed pellets was 10.2 cm. 3 is.

[0096] The test gas, a mixture of 1100 ppm ammonia and nitrogen, was passed through the quartz column at a flow rate of 5.1 L / min (space velocity 30,000 (1 / h)). The calculated pressure loss during passage was 3.9 Pa. These test conditions were the same as those in Example 1 in terms of space velocity. The pressure loss is not limited to the examples, but the present invention can be used if it is, for example, about 0.01 Pa to 100 kPa. The pore size distribution and the median pore size of the honeycomb structure obtained in Example 1 and the granules of Comparative Example 1 were measured by mercury porosimetry (in accordance with JIS R1655:2003). FIG. 7 is a graph showing the pore size distribution of the honeycomb structure obtained in Example 1 and the granules of Comparative Example 1. The median diameter was 220 nm in Example 1 and 18 nm in Comparative Example 1.

[0097] The adsorbents of the Examples and Comparative Examples were evaluated for the amount of ammonia adsorbed and the rate of ammonia adsorption. FIG. 5 is a schematic diagram of an evaluation device for the amount of ammonia adsorption and the rate of ammonia adsorption. The mixed gas of ammonia and nitrogen is prepared as a test gas with a predetermined ammonia concentration by mixing gases from the ammonia cylinder 40 and the nitrogen cylinder 50 in a predetermined ratio. Mass flow controllers 41 and 51 for adjusting the flow rates are connected to the ammonia cylinder 40 and the nitrogen cylinder 50, respectively. The adsorbent 100 to be subjected to the ammonia adsorption test is placed in the thermostatic chamber 60 set at 25° C., and the test gas is introduced into the adsorbent 100 . FIG. 5 shows a honeycomb structure 1 as an adsorbent. The test gas that has passed through the adsorbent 100 is bubbled through boric acid water 70 and separated, and the ammonia in the separated liquid is quantified using a coulometric ammonia meter. The concentration of the boric acid solution is 0.05 mol / L, the interval between fractions is 10 to 20 minutes, and the bubbling time is 60 seconds.

[0098] 6 is a graph in which the horizontal axis represents the aeration time and the vertical axis represents the ammonia concentration at the outlet of the adsorbent. Note that the measurement was continued until the outlet ammonia concentration reached 1100 ppm. It can be said that the lower the outlet ammonia concentration, the greater the amount of ammonia adsorbed by the adsorbent. In Example 1, the outlet ammonia concentration was low immediately after the start of aeration. In contrast to this, in Comparative Example 1, the outlet ammonia concentration increased immediately after the start of aeration. The concentration of the adsorbed ammonia is not limited to that in this embodiment, and may be in any concentration range.

[0099] The amount of ammonia adsorbed until the ammonia concentration on the outlet side reached 1100 ppm was measured. The ammonia adsorption rate was calculated by dividing the amount of ammonia adsorbed by the time taken from immediately after the start of the test until the outlet ammonia concentration reached 1100 ppm. The results are summarized in Table 1.

[0100] [Table 1]

[0101] Comparing Example 1 and Comparative Example 1, both the amount of ammonia adsorbed and the adsorption rate per unit weight of the Prussian blue complex were greater in Example 1, which was a honeycomb structure. From the above, it was found that when the ammonia adsorbent of Example 1, which is a honeycomb structure having a metal cyano complex in the partition walls, is used, both the amount of ammonia adsorbed and the adsorption speed are excellent. [Explanation of symbols]

[0102] 1, 2, 3, 4 Honeycomb structure 10, 11, 12, 13 Through holes 20 Bulkhead 31 Inlet end face 32 Outlet side end face 40 Ammonia Cylinder 41, 51 Mass flow controller (MFC) 50 Nitrogen Cylinders 60 Constant temperature bath 70 Boric Acid Water 100 Adsorbent L Longitudinal direction

Claims

1. A honeycomb structure comprising partition walls that define a plurality of through holes, the partition walls containing a metal cyano complex, and used for ammonia adsorption.

2. The metal cyano complex has a main composition represented by the general formula: A ｘ M[M'(CN) ６ ] ｙ ・zH ２ O The honeycomb structure according to claim 1, wherein [In the formula, M represents one or more metal atoms selected from the group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadolinium, lutetium, barium, strontium, and calcium; M' represents one or more metal atoms selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper; A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, rubidium, and cesium; x represents a number of 0 to 3, y represents a number of 0.1 to 1.5, and z represents a number of 0 to 6.]

3. The metal cyano complex has a main composition represented by the general formula: K ２／１１ Cu[Fe(II)(CN) ６ ] ６／１１ ・zH ２ The honeycomb structure according to claim 2, wherein the pore size is O.

4. 3. The honeycomb structure according to claim 1, wherein the weight ratio of the metal cyano complex contained in the honeycomb structure is 50% by weight or more.

5. The honeycomb structure according to claim 1 or 2, wherein the partition walls contain the metal cyano complex.

6. The honeycomb structure according to claim 5 , wherein the partition walls further contain a binder and a shape-retaining agent.

7. The honeycomb structure according to claim 1 or 2, wherein the metal cyano complex is supported on the surface of the partition wall.

8. 8. The honeycomb structure according to claim 7, wherein the partition walls contain at least one selected from the group consisting of zeolite, cordierite, silicon carbide, alumina, titanium oxide, zirconia, silicon nitride, aluminum nitride, and carbon.

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