WO2008059606A1

WO2008059606A1 - Method of producing honeycomb structural body and honeycomb structural body

Info

Publication number: WO2008059606A1
Application number: PCT/JP2006/324981
Authority: WO
Inventors: Kazushige Ohno; Masafumi Kunieda; Takahiko Ido
Original assignee: Ibiden Co., Ltd.
Priority date: 2006-11-16
Filing date: 2006-12-14
Publication date: 2008-05-22

Abstract

It is intended to provide a method of producing a honeycomb structural body whereby a honeycomb structural body having a high strength and a large specific surface area can be produced. Namely, a method of producing a honeycomb structural body which comprises the molding step of using a starting composition at least containing inorganic particles, an inorganic fiber and/or whisker and an inorganic binder and producing columnar molded honeycombs, in which a large number of cells divided with cell walls are aligned in the longitudinal direction, and the calcination step of calcining the molded honeycombs as described above to give calcined honeycombs, characterized in that the average particle diameter of the inorganic binder is from 10 to 50 nm.

Description

Specification

Method for manufacturing honeycomb structure and honeycomb structure

Technical field

The present invention relates to a method for manufacturing a honeycomb structure and a honeycomb structure.

Background art

[0002] Conventionally, a hard-cam catalyst in which a catalyst component is supported on a hard-cam structure used for exhaust gas purification of a vehicle is an active alumina on the surface of a cordierite-type no-cam structure having an integral structure and low thermal expansion. It is manufactured by supporting a high specific surface area material such as platinum and a catalytic metal such as platinum. In addition, such a honeycomb catalyst carries an alkaline earth metal such as Ba as a NOx storage agent for NOx treatment in an oxygen-excess atmosphere such as a lean burn engine and a diesel engine. By the way, in order to further improve the purification performance, it is necessary to increase the contact probability between the exhaust gas, the catalyst noble metal and the NOx storage agent. For this purpose, it is necessary to make the support have a higher specific surface area, to reduce the particle size of the noble metal and to disperse it with high dispersion. For this reason, for example, a hard cam structure obtained by extruding inorganic particles and inorganic fibers together with an inorganic binder is known as a hard cam structure having a high specific surface area material force (see, for example, Patent Documents 1 to 3). ).

Patent Document 1: Japanese Patent Laid-Open No. 2005-218935

Patent Document 2: JP-A-2005-349378

Patent Document 3: Japanese Patent Laid-Open No. 5-213681

Disclosure of the invention

Problems to be solved by the invention

[0003] However, the Hercam structures disclosed in Patent Documents 1 to 3 sometimes fail to ensure a sufficient specific surface area and strength to be used as a catalyst carrier or the like.

In addition, in such a hard cam structure, when a catalyst such as a noble metal is supported due to the insufficient specific surface area, the catalyst has a sufficient purification performance with poor catalyst dispersibility. It could be easily destroyed due to the fact that it was not possible or because the strength was insufficient. Means for solving the problem

[0004] As a result of intensive studies to solve the above-mentioned problems, the present inventors have prepared a raw material composition for producing a hard structure having a large specific surface area while ensuring strength. It has been found that an inorganic binder having a predetermined average particle diameter may be used, and the present invention has been completed.

[0005] That is, in the method for producing a hard structure of the present invention, a large number of cells are separated from each other by using a raw material composition containing at least inorganic particles and inorganic fibers and / or a whisker force and an inorganic binder. And a firing process for producing a honeycomb fired body by subjecting the honeycomb formed body to a firing treatment, and a firing process for producing a pillar-shaped honeycomb formed body arranged in parallel in the longitudinal direction. Because

The average particle size of the inorganic binder in the raw material composition is 10 to 50 nm.

[0006] In the above-described method of manufacturing a her cam structure, it is desirable that the inorganic binder has an average particle size of 20 to 40 nm!

In the above-described method for producing a hercome structure, the inorganic noinda is preferably at least one selected from the group consisting of alumina sol, silica sol, titasol, water glass, sepiolite, and attapulgite.

[0007] The Hercom structure of the present invention uses a raw material composition containing at least inorganic particles, inorganic fibers, and Z or Wis power and an inorganic binder, and a large number of cells are separated from each other in the longitudinal direction with cell walls separated. A forming step of producing columnar honeycomb formed bodies arranged side by side;

The honeycomb formed body is fired to produce a honeycomb fired body.

[0008] In the above-mentioned hard cam structure, the inorganic binder preferably has an average particle size of 20 to 40 nm.

In the above-mentioned hard cam structure, the inorganic binder is preferably at least one selected from the group force consisting of alumina sol, silica sol, titasol, water glass, sepiolite and attapulgite. [0009] Further, in the above-mentioned Hercam structure, it is desirable that the catalyst is supported. The catalyst is selected from the group consisting of a noble metal, an alkali metal, an alkaline earth metal, and an oxide. It should be at least one.

In addition, the above-mentioned hard cam structure is desirably used for exhaust gas purification of vehicles.

The invention's effect

[0010] The method for manufacturing a hard cam structure of the present invention uses an inorganic binder having a predetermined average particle diameter, and therefore, a hard cam structure having a high strength and a large specific surface area can be manufactured. it can.

[0011] Further, the honeycomb structure of the present invention has a large specific surface area and excellent strength, and can be suitably used as a catalyst carrier.

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] First, a method for manufacturing a her cam structure of the present invention will be described.

The manufacturing method of the hercom structure of the present invention uses a raw material composition containing at least inorganic particles and inorganic fibers and z or a swirl force and an inorganic binder, and a large number of cells are arranged in the longitudinal direction across the cell wall. A forming step of producing a provided columnar honeycomb formed body,

A firing process for producing a honeycomb fired body by subjecting the honeycomb formed body to a firing treatment,

The inorganic binder has an average particle size of 10 to 50 nm.

[0013] Hereinafter, a method for manufacturing a her cam structure of the present invention will be described in the order of steps.

(1) In the method for producing a hercome structure of the present invention, first, a large number of cells have a cell wall formed using a raw material composition containing at least inorganic particles and inorganic fibers and Z or Wis power and an inorganic binder. A forming process for producing columnar honeycomb formed bodies arranged in parallel in the longitudinal direction at a distance is performed.

[0014] The raw material composition includes at least inorganic particles and inorganic fibers, and Z or a whisker and an inorganic binder. Further, if necessary, an organic binder dispersion medium and a molding aid are adjusted to the moldability. Can be used as appropriate.

[0015] In the method for producing a her cam structure of the present invention, as the inorganic binder, an average particle size of Use an inorganic binder with a lower limit of 10 nm and an upper limit of 50 nm. By using such an inorganic binder, a hard structure having a large specific surface area and excellent strength can be manufactured through the manufacturing process described later.

When the average particle size of the inorganic binder is less than lOnm or more than 50 nm, the strength of the manufactured no-cam structure becomes insufficient. The reason is considered as follows.

That is, in the method for producing a hard structure of the present invention, the inorganic binder is considered to play a role of mainly bonding the inorganic particles, the inorganic fibers, and the whiskers, and between the inorganic fibers and the inorganic particles. It is considered that the adhesive function is exerted by contacting the inorganic fibers and the inorganic particles at the same time, interposing between the inorganic particles and contacting different inorganic particles at the same time.

Here, when the average particle diameter is less than lOnm, it is difficult to contact the inorganic fibers and the inorganic particles at the same time, or to contact different inorganic particles at the same time, and a sufficient adhesive force cannot be obtained. On the other hand, if the average particle diameter exceeds 50 nm, the number of adhesion points will decrease, and as a result, the strength will be insufficient.

Furthermore, when the average particle size of the inorganic binder exceeds 50 nm, the specific surface area of the manufactured Hercam structure is not sufficiently large, which is disadvantageous when the honeycomb structure is used as a catalyst carrier. .

Further, the desirable average particle size of the inorganic binder has a lower limit of 20 nm and an upper limit force Onm.

[0016] As the inorganic binder, an inorganic sol clay binder or the like can be used, and specific examples of the inorganic sol include alumina sol, silica sol, titer sol, water glass and the like. Examples of the clay-based binder include double-chain structure type clays such as clay, kaolin, montmorillonite, sepiolite, and attapulgite. These may be used alone or in combination of two or more.

Among these, at least one selected from the group force consisting of alumina sol, silica sol, titasol, water glass, sepiolite and attapulgite is desirable.

[0017] The amount of the inorganic binder is the solid content, and the inorganic particles and the inorganic fibers. And the desirable lower limit is 5% by weight, and the more desirable lower limit is 10% by weight, based on the total amount of z or Wis power and the solid content of the inorganic binder (hereinafter referred to as the total amount of essential raw materials). A desirable lower limit is 15% by weight. On the other hand, the desirable upper limit is 50% by weight, the more desirable upper limit is 40% by weight, and the more desirable upper limit is 35% by weight.

If the amount of the inorganic binder is less than 5% by weight, the strength of the manufactured hard cam structure may be lowered. On the other hand, if the amount of the inorganic binder exceeds 50% by weight, the moldability of the raw material composition may be reduced. It tends to get worse.

[0018] The average particle size of the inorganic binder can be measured, for example, by the following method.

Specifically, when the inorganic noinda is a silica sol, the silica sol is first dried and its BET specific surface area is measured.

Then, assuming that the silica particles in the silica sol are dense spherical particles, the following calculation formula (1) is used.

BET specific surface area = (6000 / _P ) Z particle size '· · · (1)

(Wherein p is the true density of silica (2.2 gZcm ³ ))

The average particle size of the inorganic binder can also be directly measured using, for example, a TEM (transmission electron microscope).

[0019] Examples of the inorganic particles include alumina, silica, zirconia, titer, ceria, mullite, and zeolite. These may be used alone or in combination of two or more. Of these, alumina particles and ceria particles are particularly desirable.

[0020] With respect to the blending amount of the inorganic particles, a desirable lower limit is 30% by weight, a more desirable lower limit is 40% by weight, and a further desirable lower limit is 50% by weight with respect to the total amount of the essential raw materials. On the other hand, a desirable upper limit is 90% by weight, a more desirable upper limit is 80% by weight, and a further desirable upper limit is 75% by weight.

When the amount of the inorganic particles is less than 30% by weight, the amount of inorganic particles contributing to the improvement of the specific surface area is relatively small. Therefore, the specific surface area of the manufactured nonicum structure is small and the catalyst component is supported. In some cases, the catalyst component cannot be highly dispersed. On the other hand, if it exceeds 90% by weight, inorganic binder, inorganic fiber, whisker contribute to strength improvement. Therefore, the strength of the manufactured nonicam structure tends to decrease.

[0021] In addition, it is desirable that the inorganic particles to be blended in the raw material composition have an average secondary particle size of 0.5 to 20 μm! / !.

When the average particle diameter is less than 0.5 m, the produced no-cam structure is densified, and when used as a catalyst carrier, the gas permeability may be inferior, while exceeding And the specific surface area of the manufactured honeycomb structure tends to be small.

The average particle size of the primary particles of the inorganic particles is preferably 5 to: LOOnm. In the present specification, primary particles are particles constituting a powder aggregate, and are the smallest unit particles that exist without breaking bonds between molecules. Secondary particles are particles formed by agglomeration of primary particles.

[0022] The inorganic particles (secondary particles) preferably have a specific surface area of 50 to 300 m ² / g.

When the specific surface area is less than 50 m ² Zg, the specific surface area of the manufactured honeycomb structure tends to be small. On the other hand, when the specific surface area exceeds 300 m ² Zg, the specific surface area of the two-cam structure is increased even if the specific surface area is increased. This is because the specific surface area does not improve so much.

Moreover, in the method for producing a her cam structure of the present invention, the average aspect ratio of the inorganic particles (secondary particles) is 1 to 5.

[0023] Examples of the inorganic fiber whisking force include alumina, silica, silicon carbide, silica-alumina, glass, potassium titanate, aluminum borate and the like.

These inorganic fibers can be used alone or in combination of two or more.

In the method of manufacturing a her cam structure of the present invention, the inorganic fiber whisking force has an average aspect ratio exceeding 5.

The desirable average aspect ratio of the inorganic fiber wis power is 10 to: LOOO.

[0024] The total blending amount of the inorganic fiber and Z or the whisking force is preferably 3% by weight, more preferably 5% by weight, and further preferably 8% by weight based on the total amount of the essential raw materials. %. On the other hand, the desirable upper limit is 50% by weight, and the more desirable upper limit is 40% by weight, and a more desirable upper limit is 30% by weight.

If the total amount of the inorganic fiber and Z or the whisking force is less than 3% by weight, the strength of the manufactured honeycomb structure is reduced. On the other hand, if it exceeds 50% by weight, the manufactured honeycomb structure is reduced. In this case, since the amount of inorganic particles contributing to the improvement of the specific surface area is relatively small, there is a case where the specific surface area of the her cam structure is small and the catalyst component cannot be highly dispersed when the catalyst component is supported. is there.

[0025] The organic binder is not particularly limited, and examples thereof include methyl cellulose, canoleoxymethylenoresenorelose, hydroxyethinoresenorelose, and polyethylene glycol.

These may be used alone or in combination of two or more.

The blending amount of the organic binder is desirably 1 to L0 parts by weight with respect to 100 parts by weight of the solid content of the inorganic particles, the inorganic fibers, the whiskers, and the inorganic binder.

[0026] The dispersion medium is not particularly limited, and examples thereof include water, organic solvents (such as benzene), alcohols (such as methanol), and the like.

The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid sarcophagus, and polyalcohol.

[0027] Preparation of the raw material composition is not particularly limited, but it is preferable to mix and knead the raw materials. For example, a kneader that may be mixed using a mixer, an attritor, or the like. Knead thoroughly.

[0028] Next, the raw material composition is extruded to produce a columnar honeycomb formed body in which a large number of cells are arranged in parallel in the longitudinal direction with cell walls interposed therebetween.

[0029] (2) Next, if necessary, the honeycomb formed body is dried.

The drying treatment can be performed using, for example, a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer, or the like.

[0030] (3) Next, the honeycomb formed body that has been subjected to a drying treatment as necessary is subjected to a degreasing treatment as necessary.

In this case, the degreasing conditions are not particularly limited, and are appropriately selected depending on the type and amount of the organic substance contained in the molded body, but are preferably about 400 ° C. and about 2 hours. [0031] (4) Next, a firing process is performed to produce a honeycomb fired body by subjecting the Hercam molded body, which has been subjected to a drying process and a degreasing process, as necessary, to a firing process.

The firing temperature in the firing treatment is not particularly limited, but 500-1200 ° C is desirable, and 600-1000 ° C is more desirable.

If the firing temperature is less than 500 ° C, the adhesive function due to the inorganic binder is difficult to develop, and the sintering of the inorganic particles or the like hardly progresses, so the strength of the manufactured honeycomb structure may be lowered. When the temperature exceeds 1200 ° C, the sintering of inorganic particles proceeds too much, and the specific surface area per unit volume of the manufactured Hercam structure becomes small. When the Hercam structure is used as a catalyst support, In some cases, the catalyst component to be supported cannot be sufficiently dispersed.

[0032] By passing through such a process, a columnar hard cam fired body in which a large number of cells are arranged in parallel in the longitudinal direction across the cell wall can be produced.

The no-cam fired body manufactured through such steps is itself a her cam structure, and in the method for manufacturing the her cam structure of the present invention, all the steps may be completed so far. . In addition, a seal material layer (coat layer) may be formed around the no-cam fired body manufactured by the method described so far to obtain a finished product of the her cam structure. Such a her cam structure having a single hard cam firing strength is also referred to as an integrated her cam structure hereinafter.

The method for forming the sealing material layer (coating layer) is as follows. When a honeycomb structure is manufactured by bundling a plurality of hard cam fired bodies described later, a sealing material layer (coating layer) is formed around the honeycomb block. It is the same as the method of forming.

[0033] Further, in the method of manufacturing a her cam structure of the present invention, after manufacturing a her cam fired body by the above-described method, a plurality of the honeycomb fired bodies are bundled to manufacture a honeycomb structure. Also good.

In this case, specifically, the following method may be used.

A her cam structure formed by binding a plurality of her cam fired bodies is hereinafter also referred to as a collective her cam structure.

[0034] That is, a sealing material paste to be a sealing material layer (adhesive layer) is applied to the obtained her cam fired body to sequentially bind the her cam fired body, and then dried and fixed. , Sealing material An aggregate of honeycomb fired bodies of a predetermined size that are bound through layers (adhesive layers) is produced.

Further, after assembling a predetermined number of her-cam fired bodies through a spacer, a sealing material paste is injected into the gap between the her-cam fired bodies, and then dried, fixed, and sealed. An aggregate of honeycomb fired bodies of a predetermined size that are bound through layers (adhesive layers) may be produced.

[0035] The sealing material paste for forming the adhesive layer is not particularly limited, but for example, a mixture of an inorganic binder and ceramic particles, or a mixture of an inorganic binder and inorganic fibers. Or a mixture of an inorganic binder, ceramic particles and inorganic fibers can be used.

Further, an organic binder may be added to these sealing material pastes.

[0036] The organic binder is not particularly limited, and examples thereof include polyvinyl alcohol, methenoresenorelose, ethinoresenorelose, canoleoxy methinoresenorelose and the like.

These can be used alone or in combination of two or more.

[0037] The thickness of the sealing material layer (adhesive layer) is preferably 0.5 to 5 mm.

If the thickness of the sealing material layer (adhesive layer) is less than 0.5 mm, sufficient bonding strength may not be obtained. If the thickness exceeds 5 mm, the sealing material layer (adhesive layer) serves as a catalyst carrier. Since the portion does not function, the specific surface area per unit volume of the her cam structure is reduced, and when the catalyst component is supported, it may not be possible to sufficiently disperse the catalyst component.

If the thickness of the sealing material layer (adhesive layer) exceeds 5 mm, the pressure loss may increase.

[0038] Here, the number of the honeycomb fired bodies to be bundled may be appropriately determined according to the size of the honeycomb structure. In addition, the aggregate of honeycomb fired bodies in which the hard cam fired bodies are bundled through a sealing material layer (adhesive layer) is appropriately cut, polished, or the like as necessary to form a honeycomb block.

[0039] Next, if necessary, a sealant paste for forming a coat layer is applied to the outer peripheral surface of the her cam block, dried, and fixed to form a sealant layer (coat Shape) To do.

By forming the sealing material layer (coat layer), the outer peripheral surface of the her cam block can be protected, and as a result, the strength of the her cam structure can be increased.

[0040] The sealing material paste for forming the coating layer is not particularly limited, and may be made of the same material as the sealing material paste for forming the adhesive layer, or may be made of a different material. It may be.

Further, when the sealing material paste for forming the coating layer is made of the same material as the sealing material paste for forming the adhesive layer, the blending ratios of both components are the same. It may or may not be different.

[0041] The thickness of the sealing material layer (coat layer) is not particularly limited, but is preferably 0.1-2 mm. If the thickness is less than 1 mm, the outer peripheral surface may not be protected and the strength may not be increased. If the thickness exceeds 2 mm, the specific surface area per unit volume of the her-cam structure decreases, and the catalyst component is supported. When this occurs, it may not be possible to achieve sufficiently high dispersion.

[0042] Further, in this manufacturing method, after binding a plurality of her cam fired bodies through a sealing material layer (adhesive layer) (provided that a sealing material layer (coat layer) is provided) It is desirable to calcine after forming the coat layer.

This is because the organic binder can be degreased and removed when the sealing material layer (adhesive layer) or the sealing material layer (coat layer) contains an organic binder. The conditions for calcining are appropriately determined depending on the type and amount of organic substances contained, but it is desirable that the conditions are approximately 700 ° C and 2 hours.

Next, the her cam structure of the present invention will be described.

The Hercom structure of the present invention uses a raw material composition containing at least inorganic particles, inorganic fibers, and Z or Wis force and an inorganic binder, and a large number of cells are juxtaposed in the longitudinal direction across the cell wall. Forming step to produce a columnar honeycomb formed body,

The honeycomb formed body is fired to produce a honeycomb fired body.

The inorganic binder in the raw material composition has an average particle size of 10 to 50 nm. It is a sign.

Note that in this specification, the column shape includes an arbitrary column shape such as a columnar shape, an elliptical column shape, or a polygonal column shape.

[0044] The her cam structure of the present invention is a her cam structure manufactured through at least the molding step and the firing step, and has an average particle size of the inorganic binder used in the molding step. The diameter is 10-50 nm.

Therefore, the her cam structure of the present invention can be manufactured by using the method of manufacturing the her cam structure of the present invention already described.

[0045] Hereinafter, the configuration of the her cam structure of the present invention will be described with reference to the drawings.

Fig. 1 (a) is a perspective view schematically showing an example of a no- and two-cam fired body (an example of a no-dum and two-cam structure) manufactured through a firing step, and (b) is an illustration of (a) FIG. 6 is a perspective view schematically showing another example of the hard cam structure of the present invention using the hard cam fired body shown in FIG.

[0046] As shown in Fig. 1 (a), the honeycomb fired body 20 has a quadrangular prism shape, and a large number of cells 21 are separated from each other by the cell wall 22 in the longitudinal direction (in Fig. 1 (a), the arrow a Direction).

As shown in FIG. 1 (b), the her cam structure 10 of the present invention includes a plurality of her cam fired bodies 20 shown in FIG. 1 (a) with a sealing material layer (adhesive layer) 14 interposed therebetween. The ceramic blocks 15 are bound together to form a sealing material layer (coat layer) 13 on the outer periphery thereof.

[0047] In the above hard cam fired body, the thickness of the cell wall is not particularly limited. Force The desirable lower limit is 0.05 mm, the more desirable lower limit is 0.10 mm, and the particularly desirable lower limit. Is 0.15mm. On the other hand, the desirable upper limit of the cell wall thickness is 0.35 mm, the more desirable upper limit is 0.30 mm, and the particularly desirable upper limit is 0.25 mm.

[0048] If the cell wall thickness is less than 0.05 mm, the strength of the Hercam fired body may be reduced. On the other hand, if the cell wall thickness exceeds 0.35 mm, the Hercam When the structure is used as a catalyst carrier for purifying exhaust gas, the contact area with the exhaust gas is reduced and the gas does not penetrate deep enough, so the catalyst supported inside the cell wall and the gas come into contact with << As a result, the gas purification performance may deteriorate.

[0049] Further, the cell density of the above-mentioned Hercam fired body has a desirable lower limit of 15.5 pieces / cm ² (100 cpsi), and a more desirable lower limit force of 6.5 pieces Zcm ² (300 cpsi), and is further desirable. Lower limit is 62 Zcm ² (400cpsi). On the other hand, the desirable upper limit of the cell density is 186 Zcm ² (1200 cpsi), the more desirable upper limit is 170.5 Zcm ² (1100 cpsi), and the more desirable upper limit is 155 Zcm ² (1000 cpsi).

If the cell density force is less than 15.5 Zcm ² , the area of the cell wall in contact with the exhaust gas inside the honeycomb fired body is small when the above-mentioned Hercom structure is used as a catalyst carrier for purifying the exhaust gas. This is because if it exceeds 186 / cm ² , the pressure loss becomes high and it becomes difficult to fabricate a hermetic fired body.

[0050] Further, it is desirable that the lower limit of the sectional area in the direction perpendicular to the longitudinal direction of the her cam fired body is 5 cm ² and the upper limit is 50 cm ^2. Is a range formed by binding a plurality of honeycomb fired bodies, it is desirable to be within the above range. If the cross-sectional area is less than 5 cm ² , the area occupied by a sealing material layer (adhesive layer) that joins a plurality of her-cam fired bodies in the cross-section perpendicular to the longitudinal direction of the her-cam structure However, when the honeycomb structure is used as a catalyst carrier, the area on which the catalyst can be supported becomes relatively small. On the other hand, if the cross-sectional area exceeds 50 cm ² , the honeycomb fired body is large, and thus there is a fear that the thermal stress generated in the honeycomb fired body cannot be sufficiently suppressed.

A more desirable lower limit of the cross-sectional area is 6 cm ² , a particularly desirable lower limit is 8 cm ² , and a more desirable upper limit is 40 cm ² , especially desirable! /, And an upper limit is 30 cm ² .

[0051] The shape of the cross section perpendicular to the longitudinal direction of the cells formed in the honeycomb fired body is not particularly limited, and is substantially a triangle other than the square shape like the nonicum fired body shown in Fig. 1 (a). Or a substantially hexagonal shape.

[0052] Further, when a sealing material layer (adhesive layer) or a sealing material layer (coat layer) is formed on the her cam structure, in a cross section perpendicular to the longitudinal direction of the honeycomb structure, The ratio of the total cross-sectional area of the honeycomb fired body to the cross-sectional area of the honeycomb structure is preferably 90% or more. If it is less than 90%, the specific surface area of the her cam structure will be small.

[0053] Further, the specific surface area per unit area of the her cam structure of the present invention is desirably 25000 m ² ZL or more. This is because when the specific surface area is in the above range, it becomes easy to disperse and carry the catalyst sufficiently widely over the entire honeycomb structure.

The desirable upper limit of the specific surface area is 70000 m ² ZL in consideration of the dispersion limit of the catalyst (for example, platinum).

[0054] More specifically, the higher the bending strength of the honeycomb structure, the more desirable it is, for example, when the honeycomb fired body has a prismatic shape of 37 mm X 37 mm X 75 mm, which is 3. OMpa or more. It is desirable.

This is a force that reduces the possibility of destruction due to thermal stress generated during use.

[0055] The her-cam structure of the present invention is not limited to the collective her-cam structure as shown in FIG. 1 (b), but is an integrated her-cam structure as shown in FIG. It may be.

FIG. 2 is a perspective view schematically showing another example of the her cam structure of the present invention.

A hard cam structure 30 shown in FIG. 2 has a columnar shape, and a large number of cells 31 are arranged side by side in the longitudinal direction (in the direction of arrow b in FIG. 2) with the cell walls 32 therebetween. It consists of one piece.

In such an integrated her cam structure, a seal material layer (coat layer) may be formed around the her cam fired body.

[0056] It is desirable that a catalyst is supported on the Hercam structure of the present invention having such a configuration. The Hercom structure of the present invention is a force that can be suitably used as a catalyst carrier.

The catalyst is not particularly limited, and examples thereof include noble metals, alkali metals, alkaline earth metals, and oxides. These may be used alone or in combination of two or more.

[0057] Examples of the noble metal include platinum, noradium, rhodium, and the like. Examples of the alkali metal include potassium and sodium. Examples of the alkaline earth metal include, for example, Norium and the like, and examples of the acid oxide include perovskite (La

0. 75

K MnO) and CeO.

0. 25 3 2

[0058] The Hercam structure on which the catalyst as described above is supported is not particularly limited. For example, it can be used as a so-called three-way catalyst or NOx occlusion catalyst for automobile exhaust gas purification. Togashi.

The timing for loading the catalyst is not particularly limited, and it may be loaded after the Hercam structure is produced, or may be loaded on the inorganic particles in the raw material composition. Further, the catalyst loading method is not particularly limited, and for example, the impregnation method can be used.

Heretofore, the case where the Hercam structure of the present invention is mainly used as a catalyst carrier has been described as an example. However, the honeycomb structure may be used other than the catalyst carrier. For example, it can also be used as an adsorbent for adsorbing gas components and liquid components.

Example

[0060] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Example 1)

(1) γ-alumina particles (average secondary particle size 2 μm) 2250 g as inorganic particles, aluminum borate whiskers (fiber diameter 0.5-1 m, fiber length 10-30 μm) as inorganic fibers 680 g, silica sol (average particle size 30 nm, solid concentration 30 weight ⁰ / _O ) 2600 g as inorganic noda, and 320 g of methyl cellulose as organic binder, and uniloop as lubricant (manufactured by NOF Corporation) 290 g and 225 g of glycerin (manufactured by NOF Corporation) as a plasticizer were added and further mixed and kneaded to prepare a raw material composition. Next, this mixed composition was subjected to extrusion molding with an extruder to produce a honeycomb formed body.

[0061] (2) Next, the honeycomb formed body was sufficiently dried using a microwave dryer and a hot air dryer, and further degreased by being held at 400 ° C for 2 hours.

After that, it was held at 900 ° C for 2 hours and fired, prismatic (37mm x 37mm x 75mm), cell density 93 pieces Zcm ² (600cpsi), cell wall thickness 0.2mm, cell cross-sectional shape A square (square) honeycomb fired body was manufactured.

[0062] (Examples 2 to 5)

As in Example 1, except that silica sol (solid concentration 30% by weight) having the average particle size shown in Table 1 was used as the inorganic binder used when preparing the raw material composition. A honeycomb fired body was manufactured.

[0063] (Example 6)

As inorganic particles, instead of γ-alumina particles, γ-alumina particles (average particle size of secondary particles 2 μ χη) 50% by weight and 13 zeolite particles (average particle size of secondary particles 2 μm) 50% by weight A hard cam fired body was produced in the same manner as in Example 1 except that the mixed particles were used.

[0064] (Example 7-: LO)

A honeycomb fired body was manufactured in the same manner as in Example 6 except that silica sol (solid concentration 30% by weight) having the average particle size shown in Table 1 was used as the inorganic binder used in preparing the raw material composition. did.

[Example 11]

As inorganic particles, instead of γ-alumina particles, 50% by weight of γ-alumina particles (average particle size of secondary particles 2 μτα) and 50% by weight of CeO particles (average particle size of secondary particles 2 μm) Grain

2

A Hercam fired body was produced in the same manner as in Example 1 except that the child was used.

[0066] (Examples 12 to 15)

A honeycomb fired body was manufactured in the same manner as in Example 11, except that silica sol (solid concentration 30% by weight) having the average particle size shown in Table 1 was used as the inorganic binder used in preparing the raw material composition. did.

[0067] (Comparative Examples 1 and 2)

A honeycomb fired body was manufactured in the same manner as in Example 1 except that silica sol (solid concentration: 30% by weight) having the average particle size shown in Table 1 was used as the inorganic binder used in preparing the raw material composition. did.

[0068] (Comparative Examples 3 and 4)

[0069] (Comparative Examples 5 and 6)

As in Example 11, except that silica sol (solid concentration 30% by weight) having the average particle size shown in Table 1 was used as the inorganic binder used when preparing the raw material composition. A honeycomb fired body was manufactured.

[0070] Evaluation of honeycomb fired body

With respect to the her-cam fired bodies produced in the examples and comparative examples, the bending strength and specific surface area were measured by the following methods. The results are shown in Table 1.

[0071] (Measurement of bending strength)

Using Instron 5582 with reference to JIS R 1601, a three-point bending test was performed at a span distance of 50 mm and a speed of 0.5 mm Zmin, and the bending strength of the honeycomb fired bodies according to the respective examples and comparative examples was measured.

The results are shown in Table 1.

[0072] (Specific surface area)

First, the BET specific surface area A (m ² Zg) per unit weight of the Hercum fired body was measured. The BE T specific surface area is measured using a BET measuring device (manufactured by Shimadzu Corporation, Micromeritics Flowsorb IV-2300) according to JIS-R-1626 (1996) defined by Japanese Industrial Standards.

Measurements were made by 2 point and 1 point method. For the measurement, a sample cut into a cylindrical small piece (diameter 15 mm x height 15 mm) was used.

Next, the apparent density B (g / L) of the hard cam fired body was calculated from the weight of the two cam fired body and the outer volume, and the specific surface area S (m ² ZL) of the honeycomb fired body was calculated as follows: Calculated from Equation (2). The results are shown in Table 1.

S (m ² / L) = AX B---(2)

Here, the specific surface area of the Hercam fired body refers to the specific surface area per apparent volume of the Hercam fired body.

[0073] [Table 1]

[0074] As can be seen from the results shown in Table 1 and FIG. 3, by using an inorganic binder having an average particle size of 50 nm or less, a hard cam fired body having a large specific surface area (a hard cam structure) It is clear that a hard cam fired body (no-cam structure) having excellent strength can be manufactured by using an inorganic binder having an average particle diameter of 10 to 50 mm. It was. FIG. 3 is a graph showing the relationship between the average particle diameter of inorganic noinder and the bending strength of the no-cam fired bodies produced in the examples and comparative examples.

[0075] Further, in the above-described examples and comparative examples, a single hard cam fired body was produced and evaluated as a hard cam structure, but a plurality of the hard cam fired bodies were used. Thus, the same result is obtained when the collective type hard cam structure as shown in FIGS. 1 (a) and 1 (b) is manufactured. Brief Description of Drawings

[0076] [Fig. 1] (a) is a perspective view schematically showing an example of a hard cam fired body produced through a firing step, and (b) is a perspective view showing the same as shown in (a). FIG. 2 is a perspective view schematically showing an example of a her cam structure of the present invention using a cam fired body. FIG. 2 is a perspective view schematically showing another example of the her cam structure of the present invention.

FIG. 3 is a graph showing the relationship between the average particle size of inorganic binder and the bending strength of the no-cam fired bodies produced in Examples and Comparative Examples.

Explanation of symbols

10, 30 Hercam structure

13 Sealing material layer (coat layer)

14 Sealing material layer (adhesive layer)

20 Hercam fired body

21, 31 Senore

22, 32 Senor wall

Claims

The scope of the claims

[1] A column-shaped hard-cam formed body in which a large number of cells are arranged in parallel in the longitudinal direction across a cell wall using a raw material composition containing at least inorganic particles and inorganic fibers and Z or Wis power and an inorganic binder. A molding process to produce

A method for manufacturing a honeycomb structure, wherein an average particle size of the inorganic binder in the raw material composition is 10 to 50 nm.

[2] The method for producing a hercome structure according to claim 1, wherein the inorganic binder has an average particle size of 20 to 40 nm.

[3] The method for manufacturing a honeycomb structured body according to claim 1 or 2, wherein the inorganic binder is at least one selected from the group force consisting of alumina sol, silica sol, titasol, water glass, sepiolite, and attapulgite.

[4] Using a raw material composition containing at least inorganic particles and inorganic fibers, and Z or Wis power and an inorganic binder, a columnar hard-shaped formed body in which a number of cells are arranged in parallel in the longitudinal direction across the cell wall A molding process to produce

The honeycomb formed body is subjected to a firing process to produce a honeycomb fired body at least, and a two-cam structure produced through a firing process,

A hard cam structure, wherein the inorganic binder in the raw material composition has an average particle size of 10 to 50 nm.

[5] The Hercome structure according to claim 4, wherein the inorganic binder has an average particle size of 20 to 40 nm.

6. The Herckum structure according to claim 4 or 5, wherein the inorganic binder is at least one selected from the group force consisting of alumina sol, silica sol, titasol, water glass, sepiolite, and attapulgite.

[7] The hard cam structure according to any one of claims 4 to 6, wherein a catalyst is supported.

[8] The honeycomb structure according to claim 7, wherein the catalyst includes at least one selected from the group consisting of noble metals, alkali metals, alkaline earth metals, and acidity. 9. The hard cam structure according to claim 4, which is used for exhaust gas purification of a vehicle.