Honeycomb structure

Abstract

This honeycomb structure includes a partition wall for defining a plurality of through-holes. The partition wall has a metal cyano complex. The honeycomb structure is used for ammonia adsorption.

Description

Honeycomb structure

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

[0002] Ammonia is a material whose management is of particular importance, and it is attracting attention in the fields of the environment and energy. In the energy field, it is being considered to synthesize ammonia using renewable energy, store it as chemical energy, and then use it as fuel as needed, or to extract hydrogen and use it as fuel. Ammonia is also known as a substance that causes odors in toilets and other real-world environments, and methods for deodorizing it by adsorbing and removing ammonia are being considered.

[0003] For example, Patent Document 1 discloses an ammonia adsorbent containing a metal cyano complex as an active ingredient. Patent Document 2 discloses a pellet-shaped ammonia adsorbent composed of an adsorption substrate 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 carrier having a honeycomb structure, but the pollutant to be removed is not ammonia.

[0005] Patent No. 6345774 Patent No. 7115944 Patent No. 7486148

[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.

[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] The metal cyano complex has an ammonia adsorption ability, and the honeycomb structure in which the partition walls have a metal cyano complex has a large geometric surface area (GSA), which increases the reaction rate between the ammonia in the medium and the metal cyano complex, thereby achieving an excellent ammonia adsorption rate and enabling 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: ｘ M [M' (CN) ６ ] ｙ ・zH ２ [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.]

[0011] In the honeycomb structure of the present invention, the metal cyano complex has a main composition represented by the general formula: ２／１１ Cu[Fe(II)(CN) ６ ] ６／１１ ・zH ２ O (where z is a number from 0 to 6) 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 ammonia adsorption amount can be increased.

[0013] In the honeycomb structure of the present invention, it is preferable that the partition walls contain the metal cyano complex. A honeycomb structure containing a metal cyano complex in the partition walls can adsorb ammonia in the partition walls themselves, so that there are many ammonia adsorption sites and it is 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 wall, ammonia is adsorbed by the metal cyano complex on the surface of the partition wall. 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 complex used can be reduced.

[0016] In the honeycomb structure of the present invention, the partition walls preferably contain at least one material 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 a honeycomb structure used for ammonia adsorption.

[0017] FIG. 1 is a perspective view schematically showing an example of a honeycomb structure. FIG. 2 is a perspective view schematically showing an example of another shape of the honeycomb structure. FIG. 3 is a perspective view schematically showing an example of another shape of the honeycomb structure. FIG. 4 is a perspective view schematically showing an example of another shape of the honeycomb structure. FIG. 5 is a schematic diagram of an evaluation device for ammonia adsorption amount and ammonia adsorption rate. FIG. 6 is a graph with the aeration time on the horizontal axis and the ammonia concentration at the adsorbent outlet on the vertical axis. 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, and the partition walls have a metal cyano complex and are used for adsorbing ammonia. In this specification, the term "ammonia" to be adsorbed refers to an ammonia molecule (NH ３ ) and ammonium ion (NH ４ ＋ ) and will be written as "ammonia" as a term that includes either or both of the ammonia molecule and the ammonium ion.

[0020] First, an example of the shape of a honeycomb structure will be described. The honeycomb structure has a plurality of through holes formed 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. Note that the "longitudinal direction" refers to the direction in which the through holes extend, and does not necessarily coincide with 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 partition walls 20 extend in the longitudinal direction (the direction indicated by the double-headed arrow L in Fig. 1). A medium flows into the through holes 10 from an inlet-side end face 31 of the honeycomb structure 1 and flows out from an outlet-side end face 32. When the medium passes through the through holes 10, ammonia in the medium is adsorbed by the metal cyano complexes contained in the partition walls 20.

[0022] The shape of the honeycomb structure is not particularly limited, but is preferably a columnar shape, and may be a rectangular columnar shape, an elliptical columnar shape, an oblong columnar shape, a rectangular columnar shape with rounded chamfers (for example, a triangular columnar shape or a quadrangular columnar shape with rounded chamfers), etc. The shape of the honeycomb structure 1 shown in Fig. 1 is a columnar 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 holes (the end face shape of the through holes) is not particularly limited, and can be polygonal, circular, or other shapes. When the through holes are polygonal, they can be triangular, quadrilateral (rectangular, square, rhombus, trapezoid, etc.), pentagonal, hexagonal, octagonal, or other shapes. 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 squares of 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.

[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 the honeycomb structure means the ratio of the area of ​​the spaces resulting from the 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, but is not limited to, 20 to 45 cm ２ / cm ３ The geometric surface area means a value obtained by dividing the total value of the external surface areas 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 walls may be made of a dense body or a porous body. When the partition walls are dense, the strength of the partition walls is excellent. When the partition walls are porous, the true surface area of ​​the partition walls of the honeycomb structure increases, and the number of ammonia adsorption sites increases, allowing for a further increase in the amount of ammonia adsorbed. 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 with a pore diameter in the range of 0.05 to 10 μm are present. 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 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 The BET specific surface area is the surface area of ​​the carbon nanotube measured by the BET method. ２ The BET specific surface area refers to the surface area per unit weight of the partition walls measured by gas adsorption. The BET specific surface area is measured based on JIS Z8830:2013, Method for measuring specific surface area of ​​powder (solid) 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 walls is preferably 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. The honeycomb structure 2 shown in Fig. 2 differs from the honeycomb structure 1 shown in Fig. 1 in the shape of the through holes (through holes 11). The other configurations are the same as those of the honeycomb structure 1 shown in Fig. 1. The shapes of the through holes 11 in the honeycomb structure 2 are all regular hexagons of 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] The through hole 12 is a large through hole having a larger cross-sectional area than the through hole 13, and the through hole 13 is a small through hole having a smaller cross-sectional area than the 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 shapes of the through holes are adjusted to match the shape of the periphery of the honeycomb structure.

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

[0035] Next, the metal cyano complex contained in the partition wall will be described. The metal cyano complex is a substance having a function of adsorbing ammonia and / or ammonium ions. In this specification, the phrase "the partition wall contains a metal cyano complex" means that the metal cyano complex is contained within the partition wall, or the metal cyano complex is supported on the surface of the partition wall, or both of these cases.

[0036] As the metal cyanide complex, it is preferable to use a Prussian blue complex. The Prussian blue complex is a metal cyanide complex composed of iron ions (Fe) and iron hexacyanoate ions [Fe(CN)]. ６ ] are connected three-dimensionally, and have minute spaces (void sites) of about 0.5 nm inside, which can take in ammonia molecules or ammonium ions.

[0037] In addition, by replacing iron ions with other metal ions, iron hexacyanoate ions [Fe(CN) ６ ] can be created, and an ammonia molecule or an ammonium ion 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: ｘ M [M' (CN) ６ ] ｙ ・zH ２ O (wherein 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).

[0039] The crystal structure of the metal cyano complex is generally a face-centered cubic structure, but is not particularly limited. ０．６７ Zn[Fe(CN) ６ ] ０．６７ ・zH ２ O 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, when salts are contained as impurities or when the material contains moisture 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, NH ３ and NH ４ ＋ The preferred range of the value of y varies depending on which of the two is considered as the main target of adsorption. When y is small, the [M'(CN) ６ In this case, the metal M is [M'(CN) ６ In this case, the ligands are easily adsorbed around the metal M, and in particular, NH ３ The amount of adsorption increases.

[0042] In addition, the general formula, A ｘ M [M' (CN) ６ ] ｙ ・zH ２ In O, when M' is Fe and M is identified, it is called an M-iron cyano complex. Examples of metal cyano complexes in this designation include iron-iron cyano complexes (M is Fe, M' is Fe), copper-iron cyano complexes (M is Cu, M' is Fe), zinc-iron cyano complexes (M is Zn, M' is Fe), manganese-iron cyano complexes (M is Mn, M' is Fe), cobalt-iron cyano complexes (M is Co, M' is Fe), nickel-iron cyano complexes (M is Ni, M' is Fe), etc. As the copper-iron cyano complex, copper-iron (II) cyano complexes are preferred.

[0043] Specific examples of metal cyano complexes include the following: (In the following chemical formula, z represents a number from 0 to 6.) ０．６８ Cu[Fe(CN) ６ ] ０．６５ ・3.17H ２ OK ０．４７ Cu[Fe(CN) ６] ０．６１ ・3.80H ２ OK ０．３４ Cu[Fe(CN) ６ ] ０．５７ ・3.98H ２ OK ０．０６ Cu[Fe(CN) ６ ] ０．５２ ・4.55H ２ O Mn[Fe(CN) ６ ] ０．６７ ・4.0H ２ O Fe ４ [Fe(CN) ６ ] ３ ・zH ２ OK ０．２３ Fe[Fe(CN) ６ ] ０．７４ ・3.5H ２ O Co[Co(CN) ６ ] ０．６０ ・zH ２ O Cu[Co(CN) ６ ] ０．５０ ・zH ２ OK ２／１１ Cu[Fe(II)(CN) ６ ] ６／１１ ・zH ２ O

[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, particles with an average primary particle size of 500 nm or less are preferred, more preferably 300 nm or less, and particularly preferably 100 nm or less. There is no particular lower limit to the particle size, but a practical value is 4 nm or more. In the present invention, the primary particle size refers to the diameter of the primary particle, and is determined by randomly selecting 10 primary particles from a 500,000x field of view using a scanning electron microscope, measuring their diameters, and averaging the measured diameters to determine the primary particle size. Ligands and other substances may be adsorbed to 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 possible method is to mix an aqueous solution containing dissolved ions of the metal M in the general formula above with an aqueous solution containing dissolved hexacyanoferric ions to obtain the metal cyano complex as a precipitate. However, even if the raw materials are mixed according to 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 hexacyanoferric ions to the metal M (referred to as the Fe / M ratio). In this case, focusing on 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. While there is no upper limit to the Fe / M ratio, increasing the Fe / M ratio increases costs, so it is preferable not to make the Fe / M ratio too large. 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 the partition walls contain a metal cyano complex. By containing a metal cyano complex in the partition walls, the partition walls themselves 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 is obtained by molding 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-retaining agent 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 resin, and epoxy resin. 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 having an ammonia adsorption ability, 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, and glass fibers. These may be used alone or in combination of two or more. Blending of inorganic fibers can improve the strength of the partition walls.

[0056] Examples of molding aids include ethylene glycol, dextrin, fatty acids, fatty acid soaps, and polyalcohols. Examples of plasticizers include polyoxyalkylene compounds such as polyoxyethylene alkyl ethers and polyoxypropylene alkyl ethers. Examples of dispersants include sorbitan fatty acid esters. Examples of lubricants include glycerin.

[0057] Furthermore, when the partition walls are porous, pore-forming agents such as balloons, which are micro-hollow spheres containing an oxide ceramic as a component, organic particles, graphite, etc. may be added as necessary. Examples of organic particles that can be used include spherical acrylic particles, spherical polyvinyl alcohol particles, and starch particles. The balloons are not particularly limited, and examples include alumina balloons, glass microballoons, shirasu balloons, fly ash balloons (FA balloons), and mullite balloons. Of 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 wt % or more, more preferably 80 wt % or more, and preferably 95 wt % or less. By increasing the amount of the metal cyano complex in the partition wall, the ammonia adsorption rate and the ammonia adsorption amount can be further increased.

[0059] The contents of the components of the metal cyano complex contained in the partition walls are preferably in the following proportions: binder: 1 to 15% by weight, shape retainer: 0 to 5% by weight, inorganic particles other than the metal cyano complex: 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, it is also preferable that the metal cyano complex is supported on the surface of the partition wall. By supporting the metal cyano complex on the surface of the partition wall, the surface of the partition wall can have ammonia adsorption ability. 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. Therefore, the ammonia adsorption rate is excellent, and efficient ammonia adsorption is possible. In addition, the amount of expensive metal cyano complex used can be reduced.

[0061] Hereinafter, an embodiment in which a metal cyano complex is supported on the surface of the partition wall of a honeycomb structure will be described. In this case, the material constituting the partition wall does not need to contain a metal cyano complex. The material constituting the partition wall is not particularly limited, and examples thereof include a metal material, a nonmetal material, and an organic material.

[0062] Among these, non-metallic materials (inorganic materials other than metal 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 constituting 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 having partition walls that do not contain a metal cyano complex can be obtained by forming a composition that does not contain a metal cyano complex into the shape of a honeycomb structure. Alternatively, 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 the honeycomb structure as a support material, and the metal cyano complex may be supported on the support material to increase the surface area of ​​the portion where the metal cyano complex is supported, thereby improving the dispersibility of the metal cyano complex. When a support material is used, the metal cyano complex may be attached to the support material, and the support material with the attached metal cyano complex 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 having a configuration 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 walls and ammonia adsorption by the metal cyano complex supported on the surface of the partition walls are exerted, thereby making it possible to further increase the ammonia adsorption rate and the ammonia adsorption amount.

[0071] The honeycomb structure of the present invention is used for ammonia adsorption. From the viewpoint of carbon neutrality, it is being considered to use ammonia itself as fuel or to generate hydrogen from ammonia and use the hydrogen as fuel. Therefore, it is expected that the consumption of ammonia will increase. On the other hand, in research on planetary boundaries, problems related to the circulation of nitrogen have been pointed out. Therefore, when it is possible to recover ammonia, it is necessary to convert the nitrogen atoms contained in ammonia into N. ２ It is considered preferable to recover and reuse the ammonia as it is without converting it into ammonia. The honeycomb structure of the present invention can be used as an adsorption carrier specialized for adsorbing ammonia, which meets such a demand.

[0072] The ammonia-containing medium to be circulated through the honeycomb structure may be a gas or a liquid. Examples of the ammonia-containing gas include exhaust gas from factories, livestock facilities, agricultural facilities, sewage treatment facilities, wastewater treatment facilities, and waste disposal facilities. Examples of the ammonia-containing liquid 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] The honeycomb structure can be regenerated and used as a honeycomb structure for adsorbing ammonia again by desorbing the ammonia adsorbed from the honeycomb structure and storing the ammonia in an ammonia storage container such as an ammonia cylinder. Desorption of ammonia from the honeycomb structure can be performed by heating the honeycomb structure. In this case, the heating temperature is preferably 80°C or higher and 120°C or lower. Methods for desorption of ammonia 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 or immersing it in an aqueous solvent to dissolve the ammonia into the aqueous solvent. To prevent unintended desorption of ammonia adsorbed in the honeycomb structure, adsorption of ammonia into the honeycomb structure is preferably performed in an environment of 60°C or lower.

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

[0076] When a honeycomb structure is used as an adsorbent for ammonia adsorption, a single honeycomb structure may be used, or multiple honeycomb structures may be combined. When multiple honeycomb structures are used, the honeycomb structures may be arranged in series so that the through holes of the multiple honeycomb structures are continuous, or may be arranged in parallel so that the end face area is large. Also, 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, an example of a method for manufacturing a honeycomb structure of the present invention, 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 the 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 mixture containing the metal cyano complex and in the form of a slurry that can be extruded. The raw material composition preferably contains a binder and a shape-retaining agent. Furthermore, components that may be contained in the partition walls may include the aforementioned inorganic fibers, molding aids, plasticizers, dispersants, lubricants, pore-forming agents, etc.

[0079] Next, the raw material composition is fed into an extrusion molding machine and extrusion-molded to produce a honeycomb molded body of a predetermined shape. At this time, the honeycomb molded body may be produced using a mold that produces a cross-sectional shape having a through-hole structure (shape and arrangement of the through-holes) shown in any one of Figures 1 to 4.

[0080] The honeycomb formed 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 using an electric dryer, the drying conditions are preferably 35 to 60°C and approximately 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 produced using the above procedure.

[0081] Furthermore, a metal cyano complex may be supported on the surface of the partition walls of the honeycomb structure. As a method for supporting a metal cyano complex on the surface of the partition walls of the honeycomb structure, the method described in the section "Embodiment in which a 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 that includes partition walls that define a plurality of through holes, the partition walls containing a metal cyano complex, and is used for ammonia adsorption.

[0084] The present disclosure (2) provides the metal cyano complex, the main composition of which is represented by the general formula: ｘ M [M' (CN) ６ ] ｙ ・zH ２ O (wherein 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).

[0085] The present disclosure (3) provides that the metal cyano complex has a main composition represented by the general formula: ２／１１ Cu[Fe(II)(CN) ６ ] ６／１１ ・zH ２ 0 (z represents a numerical value of 0 to 6), the honeycomb structure according to the present disclosure (2).

[0086] The present disclosure (4) is the honeycomb structure according to any one of the present disclosures (1) to (3), in which 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.

[0091] The present disclosure (9) is the honeycomb structure according to any one of the present disclosures (1) to (8), in which the metal cyano complex is a Prussian blue complex.

[0092] The present disclosure (10) is the honeycomb structure according to any one of the present disclosures (1) to (9), wherein the metal cyano complex is a copper-iron (II) cyano complex.

[0093] The present disclosure (11) is the honeycomb structure according to any one of the present disclosures (1) to (9), wherein the metal cyano complex is any one of the following metal cyano complexes (z represents a number of 0 to 6): ０．６８ Cu[Fe(CN) ６ ] ０．６５ ・3.17H ２ OK ０．４７ Cu[Fe(CN) ６ ] ０．６１ ・3.80H ２ OK ０．３４ Cu[Fe(CN) ６ ] ０．５７ ・3.98H ２ OK ０．０６ Cu[Fe(CN) ６ ] ０．５２ ・4.55H ２ O Mn[Fe(CN) ６ ] ０．６７ ・4.0H ２ O Fe ４ [Fe(CN) ６ ] ３ ・zH ２ OK ０．２３ Fe[Fe(CN) ６ ] ０．７４ ・3.5H ２ O Co[Co(CN)６ ] ０．６０ ・zH ２ O Cu[Co(CN) ６ ] ０．５０ ・zH ２ OK ２／１１ Cu[Fe(II)(CN) ６ ] ６／１１ ・zH ２ O

[0094] The present disclosure (12) is the honeycomb structure according to any one of the present disclosures (1) to (11), wherein the partition walls contain a Prussian blue complex as the metal cyano complex, methyl cellulose and hydroxymethyl cellulose as binders, and bentonite as a shape retaining agent.

[0095] The present disclosure (13) is the honeycomb structure according to any one of the present disclosures (1) to (12), in which the average primary particle diameter of the metal cyano complex is 500 nm or less.

[0096] The present disclosure (14) is the honeycomb structure according to any one of (1) to (13), wherein the partition walls contain a metal cyano complex, and the metal cyano complex is further supported on the surface of the partition walls.

[0097] The present disclosure (15) is the honeycomb structure according to any one of the present disclosures (1) to (14), which has a cylindrical shape.

[0098] The present disclosure (16) is the honeycomb structure according to the present disclosure (15), wherein the diameter of the bottom surface of the cylinder is 10 to 300 mm and the length in the longitudinal direction is 10 to 300 mm.

[0099] The present disclosure (17) is the honeycomb structure according to any one of the present disclosures (1) to (14), which has a rectangular pillar shape.

[0100] The present disclosure (18) is the honeycomb structure according to the present disclosure (17), wherein the vertical and horizontal dimensions of the base of the rectangular pillar are each 10 to 300 mm, and the length in the longitudinal direction is 10 to 300 mm.

[0101] The present disclosure (19) is a honeycomb structure according to any one of the present disclosures (1) to (18), wherein the shape and size of the through holes are different between the central part and the peripheral part of the end face of the honeycomb structure.

[0102] The present disclosure (20) is a honeycomb structure according to any one of the present disclosures (1) to (18), in which the through holes other than those on the outermost periphery of the honeycomb structure have a square shape.

[0103] The present disclosure (21) is a honeycomb structure according to any one of the present disclosures (1) to (18), in which the through holes other than those on the outermost periphery of the honeycomb structure have a regular hexagonal shape.

[0104] The present disclosure (22) is a honeycomb structure according to any one of the present disclosures (1) to (18), wherein the shapes of the through holes other than those on the outermost periphery of the honeycomb structure are a combination of regular octagonal through holes and square through holes, and the regular octagonal through holes have a larger cross-sectional area than the square through holes.

[0105] The present disclosure (23) provides a honeycomb structure having a through-hole density of 31 to 155 pcs / cm 3 on the end face thereof. ２ (200-1000 pieces / inch ２ ) The honeycomb structure according to any one of the present disclosures (1) to (22).

[0106] The present disclosure (24) is the honeycomb structure according to any one of the present disclosures (1) to (23), in which the opening ratio at the end face of the honeycomb structure is 30 to 70%.

[0107] The present disclosure (25) provides a method for producing a granular material having a geometric surface area of ​​20 to 45 cm ２ / cm ３ The honeycomb structure according to any one of the present disclosures (1) to (24) is as follows:

[0108] The present disclosure (26) is the honeycomb structure according to any one of the present disclosures (1) to (25), in which the partition walls are dense bodies.

[0109] The present disclosure (27) is the honeycomb structure according to any one of the present disclosures (1) to (25), in which the partition walls are porous.

[0110] The present disclosure (28) is the honeycomb structure according to the present disclosure (27), wherein the porosity of the partition walls is 20 to 60%.

[0111] The present disclosure (29) is the honeycomb structure according to the present disclosure (27) or (28), in which pores having a pore diameter in the range of 0.05 to 10 μm are present.

[0112] The present disclosure (30) provides a method for manufacturing a separator having a BET specific surface area of ​​100 to 1000 m ２ / g, the honeycomb structure according to any one of (27) to (29) of the present disclosure.

[0113] The present disclosure (31) is the honeycomb structure according to any one of the present disclosures (1) to (30), wherein the partition wall has a thickness of 0.10 to 0.46 mm.

[0114] The present disclosure (32) provides a method for manufacturing a septum having a density of 1.0 to 2.0 g / cm ３ The honeycomb structure according to any one of the present disclosures (1) to (31),

[0115] The present disclosure (33) is a honeycomb structure according to any one of the present disclosures (1) to (32), which is used for ammonia adsorption.

[0116] The present disclosure (34) is the honeycomb structure according to any one of the present disclosures (1) to (33), in which the amount of ammonia adsorbable per unit weight of the honeycomb structure is 1 mol / kg or more.

[0117] The present disclosure (35) is the honeycomb structure according to any one of the present disclosures (1) to (34), in which the ammonia adsorption rate per unit weight per unit time of the honeycomb structure is 0.6 mol / kg·h or more.

[0118] The present disclosure (36) is the use of the honeycomb structure according to any one of the present disclosures (1) to (35) for ammonia adsorption.

[0119] The present disclosure (37) is the use of the honeycomb structure according to the present disclosure (36) for ammonia adsorption, wherein the flow rate of the gas when passing through the honeycomb structure is 0.1 to 10 L / min.

[0120] The present disclosure (38) is the use of the honeycomb structure according to the present disclosure (36) or (37) for ammonia adsorption, wherein the space velocity of the gas when passing through the honeycomb structure is 2000 to 50000 (1 / h).

[0121] The present disclosure (39) is the use of the honeycomb structure according to any one of the present disclosures (36) to (38), in which the pressure loss when a gas is passed through the honeycomb structure is 0.01 Pa to 100 kPa, for ammonia adsorption.

[0122] EXAMPLES Hereinafter, examples will be given that more specifically disclose the present invention, but the present invention is not limited to these examples.

[0123] (Example 1) Pellet of Prussian blue complex (cylinder with an average diameter of 2 mm and a length of 7 mm) manufactured by Nanoblue Co., Ltd. was prepared as a granular metal cyano complex, and was 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 was K, represented by cas No. 126870-04-0. ２／１１ Cu[Fe(II)(CN) ６ ] ６／１１ ・zH ２ O (z is a number from 0 to 6).

[0124] A wet mixture was obtained by mixing and kneading 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 retaining agent, and 37 parts by weight of water as a dispersant. The wet mixture was extrusion-molded using an extruder to form a honeycomb molded body. This molded body was 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, 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 The geometric surface area (GSA) of the honeycomb structure was 25.4 cm ２ / cm ３ It was.

[0125] The honeycomb structure was placed in a container of a size that matched the size of the honeycomb structure, and a test gas, which was a mixed gas 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.

[0126] Comparative Example 1 Pellet of Prussian blue complex manufactured by Nanoblue Co., Ltd., prepared in Example 1, was used as a metal cyano complex in granular form without being crushed or molded. The pellet was 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.

[0127] A test gas, a mixture of 1,100 ppm ammonia and nitrogen, was passed through a quartz column at a flow rate of 5.1 L / min (space velocity of 30,000 (1 / h)). The calculated pressure loss during the flow was 3.9 Pa. These test conditions were the same as those in Example 1, combining the space velocity. The pressure loss is not limited to that in the examples, but the present invention can be used if it is approximately 0.01 Pa to 100 kPa. The pore size distribution and median pore diameter of the honeycomb structure obtained in Example 1 and the granules of Comparative Example 1 were measured by mercury intrusion 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.

[0128] The ammonia adsorption capacity and ammonia adsorption rate were evaluated for the adsorbents of each example and comparative example. Figure 5 is a schematic diagram of an apparatus for evaluating ammonia adsorption capacity and ammonia adsorption rate. A mixed gas of ammonia and nitrogen was prepared as a test gas with a predetermined ammonia concentration by mixing gases from an ammonia cylinder 40 and a nitrogen cylinder 50 in a predetermined ratio. Mass flow controllers 41 and 51 for adjusting the flow rate were connected to the ammonia cylinder 40 and the nitrogen cylinder 50, respectively. The adsorbent 100 to be subjected to the ammonia adsorption test was placed in a thermostatic chamber 60 set at 25°C, and the test gas was introduced into the adsorbent 100. Figure 5 shows a honeycomb structure 1 as the adsorbent. The test gas that passed through the adsorbent 100 was bubbled into boric acid water 70 and fractionated, and the ammonia in the fractionated liquid was quantified using a coulometric ammonia meter. The concentration of the boric acid water was 0.05 mol / L, the fractionation interval was 10 to 20 minutes, and the bubbling time was 60 seconds.

[0129] 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. 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, in Comparative Example 1, the outlet ammonia concentration was high immediately after the start of aeration. The concentration of adsorbed ammonia is not limited to that in this example and may be in any concentration range.

[0130] The amount of ammonia adsorbed until the outlet ammonia concentration reached 1100 ppm was measured. The ammonia adsorption rate was calculated by dividing the amount of ammonia adsorbed by the time from immediately after the start of the test until the outlet ammonia concentration reached 1100 ppm. The results are summarized in Table 1.

[0131]

[0132] Comparing Example 1 and Comparative Example 1, the amount and rate of ammonia adsorption per unit weight of the Prussian blue complex were both greater in Example 1, which was a honeycomb structure. From the above, it was found that when the ammonia adsorbent of Example 1, which was a honeycomb structure having a metal cyano complex in the partition walls, was used, both the amount and rate of ammonia adsorption were excellent.

[0133] REFERENCE SIGNS LIST 1, 2, 3, 4 Honeycomb structure 10, 11, 12, 13 Through-hole 20 Partition wall 31 Inlet end face 32 Outlet end face 40 Ammonia cylinder 41, 51 Mass flow controller (MFC) 50 Nitrogen cylinder 60 Thermostatic bath 70 Boric acid water 100 Adsorbent L Longitudinal direction

Claims

1. 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.

2. The metal cyano complex has a main composition represented by the general formula: ｘ M [M' (CN) ６ ] ｙ ・zH ２ 2. The honeycomb structure according to claim 1, wherein 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: ２／１１ Cu[Fe(II)(CN) ６ ] ６／１１ ・zH ２ 3. The honeycomb structure according to claim 2, wherein z is 0 (z is a number of 0 to 6).

4. The honeycomb structure according to any one of claims 1 to 3, 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 any one of claims 1 to 4, 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 any one of claims 1 to 6, wherein the metal cyano complex is supported on the surface of the partition walls.

8. A honeycomb structure according to any one of claims 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.

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