JP5843802B2 - Honeycomb catalyst carrier - Google Patents

Description

The present invention relates to a honeycomb catalyst carrier. More particularly, the present invention relates to a honeycomb catalyst carrier for supporting zeolite that can be used for selective catalytic reduction (SCR) of NO _X.

Exhaust gas discharged from internal combustion engines such as automobile engines contains harmful substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO _X ). Catalytic reactions are widely used to reduce such harmful substances and purify exhaust gas. In this catalytic reaction, it is possible to generate other harmless substances from harmful substances such as carbon monoxide (CO) by a simple means of contacting exhaust gas with the catalyst. Therefore, in automobiles and the like, it is common to purify exhaust gas by installing a catalyst in the middle of the exhaust system.

  When installing a catalyst in an exhaust system of an automobile or the like, a honeycomb catalyst body in which a catalyst is supported on a honeycomb structure is used. In the honeycomb catalyst body, a honeycomb structure is formed by partition walls supporting the catalyst. Therefore, in the honeycomb catalyst body, the contact frequency between the exhaust gas and the catalyst is high, and as a result, high purification efficiency of the exhaust gas can be realized.

  Furthermore, with regard to the honeycomb catalyst body, a technique has been proposed in which a honeycomb structure (honeycomb catalyst carrier) is formed by porous partition walls having innumerable pores, and the catalyst is supported in the pores of the partition walls. This technique is to increase the amount of catalyst supported in the honeycomb catalyst body by supporting the catalyst in the pores. Thus, an improved technique has been proposed in which the porosity of the partition walls is increased to increase the amount of catalyst supported on the partition walls (for example, Patent Document 1).

JP 2011-194342 A

  However, even with the above-described improved technique, if an attempt is made to support a bulky zeolite, the zeolite does not sufficiently enter the pores and deposits thickly on the surface of the partition wall. Due to the deposition of zeolite on the partition wall surface, the pressure loss of the honeycomb catalyst body increases.

  In view of the above problems, an object of the present invention is to provide a technology relating to a honeycomb catalyst carrier that makes it possible to reduce the thickness of the zeolite layer deposited on the partition wall surface by putting zeolite in the pores of the partition wall. It is in.

  The present invention is the following honeycomb catalyst carrier.

[1] A porous partition wall that forms a plurality of cells serving as fluid flow paths, the partition wall having a porosity of 40% or more, and a pore diameter distribution measured by a mercury intrusion method of the partition wall Those having a pore diameter in the range of 15 μm to 300 μm are referred to as a first pore group, those having a pore diameter in the range of 1 μm to less than 15 μm are referred to as a second pore group, and the pore diameters including the first pore group are 15 to In the range of 300 μm, there is at least one peak (I) of the pore size distribution, and in the range of pore sizes including the second pore group of 1 μm or more and less than 15 μm, the peak (II) of the pore size distribution is at least 1 and the pore volume of the first pore group is 50 to 80% of the total pore volume, and the pore volume of the second pore group is 20 to 50% of the total pore volume. And at least one of the peaks (I) has a pore diameter of 20 Present in the range of 80 [mu] m, the honeycomb catalyst carrier, present in at least Tsugahoso pore size 15μm less range of 6.2μm of the peak (II).

[ 2 ] The honeycomb catalyst carrier according to [1 ], wherein the partition wall has a thickness of 50 to 350 μm.

[3] The honeycomb catalyst carrier of the cell density according to the a 45 to 200 pieces / cm ² [1] or [2].

[ 4 ] The honeycomb catalyst carrier according to any one of [1] to [ 3 ], wherein the partition wall has a permeability of 0.5 to 6.0 μm ² .

  According to the honeycomb catalyst carrier of the present invention, when a catalyst containing zeolite is supported, the zeolite becomes thick and difficult to deposit on the surface of the partition wall. As a result, an increase in pressure loss can be suppressed in the honeycomb catalyst body using the honeycomb catalyst carrier.

1 is a schematic perspective view of an embodiment of a honeycomb catalyst carrier of the present invention. It is a schematic diagram of the A-A 'cross section in FIG. It is the schematic diagram which expanded the inside of the frame (alpha) in FIG. FIG. 3 is a schematic diagram showing pore size distribution of partition walls constituting the honeycomb catalyst carrier of one embodiment of the present invention. It is a schematic diagram which shows the outline | summary of a catalyst slurry injection | pouring process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the present invention.

1. Honeycomb catalyst carrier:
As shown in FIGS. 1 to 4, a honeycomb catalyst carrier 50 according to an embodiment of the present invention includes porous partition walls 9 that partition and form a plurality of cells 7 serving as fluid flow paths. The partition wall 9 has a porosity of 40% or more. In the honeycomb catalyst carrier 50, in the pore diameter distribution measured by the mercury intrusion method of the partition walls 9, the first pore group having a pore diameter in the range of 15 μm to 300 μm and the second fine pore having a pore diameter in the range of 1 μm to less than 15 μm. There is a group of holes. Then, at least one peak (I) of the pore diameter distribution exists in the pore diameter range of 15 to 300 μm including the first pore group. Further, at least one peak (II) of the pore diameter distribution exists in the range of the pore diameter including the second pore group of 1 μm or more and less than 15 μm. Furthermore, the pore volume of the first pore group is 50 to 80% of the total pore volume. The pore volume of the second pore group is 20 to 50% of the total pore volume.

  FIG. 1 is a schematic perspective view of a honeycomb catalyst carrier 50 according to an embodiment of the present invention as viewed from the first end face 3 side. FIG. 2 is a schematic diagram showing a cross section along the line A-A ′ in FIG. 1, specifically, along a cell extending direction of the honeycomb catalyst carrier 50 (hereinafter simply referred to as “Z direction”). FIG. 3 is an enlarged schematic view of the inside of the frame α in FIG. FIG. 4 is a schematic diagram showing the pore size distribution of the partition walls 9 constituting the honeycomb catalyst carrier 50 of one embodiment of the present invention.

  According to the honeycomb catalyst carrier 50, when the catalyst containing zeolite is supported on the partition walls 9, a large amount of a slurry containing zeolite (hereinafter referred to as “catalyst slurry”) is filled in the pores 11 constituting the first pore group. The Next, excess water contained in the catalyst slurry passes through the pores 15 constituting the second pore group and is discharged to the outside of the partition walls 9. Since such a smooth flow of the catalyst slurry is formed, in the honeycomb catalyst carrier 50, it becomes possible to sufficiently put zeolite into the pores 11 constituting the first pore group. Along with this, according to the honeycomb catalyst carrier 50, when a catalyst containing zeolite is supported, the zeolite becomes thick and difficult to deposit on the surface of the partition wall 9. As a result, in the honeycomb catalyst body using the honeycomb catalyst carrier 50, an increase in pressure loss can be suppressed.

  In the present specification, the “porosity of the partition wall 9” is a value measured by a mercury porosimeter (mercury intrusion method).

  In the present specification, the “pore diameter of the partition wall 9” is a value measured by a mercury porosimeter (mercury intrusion method).

  In this specification, “pore size distribution measured by mercury porosimetry” means the pore diameter data measured by mercury porosimetry as shown in FIG. It means the pore size distribution displayed by a graph in which the axis is defined as the pore size (μm).

  In the present specification, “peak (I)” means a peak appearing in a pore diameter range of 15 to 300 μm in the above-mentioned pore diameter distribution. When a plurality of peaks appear in a pore diameter range of 15 to 300 μm, all of the plurality of peaks are “peak (I)”.

  In the present specification, “peak (II)” means a peak appearing in the range of the pore diameter of 1 μm or more and less than 15 μm in the above-mentioned pore diameter distribution. When a plurality of peaks appear in a range of 1 μm or more and less than 15 μm, each of the plurality of peaks is “peak (II)”.

In the honeycomb catalyst carrier 50, present in a range of at least 1 Tsugahoso pore size 20~80μm peak (I), and, that exist in at least Tsugahoso pore size 6.2 range below μm or 15μm peak (II) . When the peak (I) is present in the pore diameter range of 20 to 80 μm and the peak (II) is present in the pore diameter range of 6.2 μm or more and less than 15 μm, the pore connectivity is excellent.

  In the honeycomb catalyst carrier 50, the partition wall 9 preferably has a thickness of 50 to 350 μm. Moreover, when the thickness of the partition walls 9 is less than 50 μm, the structural strength of the honeycomb catalyst carrier 50 may be inferior. When the thickness of the partition wall 9 exceeds 350 μm, the air permeability of the partition wall 9 may be inferior. Furthermore, the thickness of the partition wall 9 is more preferably 50 to 200 μm, and most preferably 50 to 160 μm.

  In the present specification, the “thickness of the partition wall 9” means the thickness of the partition wall 9 that partitions two adjacent cells 7 in a cross section perpendicular to the Z direction. The “thickness of the partition wall 9” can be measured by, for example, an image analyzer (trade name “NEXIV, VMR-1515” manufactured by Nikon Corporation).

In the honeycomb catalyst carrier 50, the cell density is preferably 45 to 200 cells / cm ² . When the cell density is 45 to 200 cells / cm ² , the honeycomb catalyst carrier 50 is excellent in strength and pressure loss. In addition, when the cell density is less than 45 cells / cm ² , the contact area with the exhaust gas becomes small, so that the purification performance after the catalyst coating may be inferior. When the cell density exceeds 200 cells / cm ² , the opening area becomes small, which may increase the pressure loss. Further, the cell density is more preferably from 45 to 140 pieces / cm ^2, particularly, most preferably from 45 to 120 pieces / cm ^2.

In this specification, “cell density” means the number of cells 7 per unit area (per 1 cm ² ) in a cross section perpendicular to the Z direction.

In the honeycomb catalyst carrier 50, it is preferable that the permeability of the partition walls 9 is 0.5 to 6.0 μm ² . When the permeability of the partition walls 9 is 0.5 to 6.0 μm ² , the pores are excellently connected. When the permeability of the partition wall 9 is less than 0.5 μm ² , the water permeability to the partition wall 9 may be inferior. When the permeability of the partition wall 9 is more than 6.0 μm ² , the structure constituting the partition wall 9 is weak and the strength may be inferior. Furthermore, the permeability of the partition walls is more preferably 0.5 to 3.0 μm ² .

In this specification, the “permeability of the partition wall 9” refers to a physical property value calculated by the following formula (1), and is a value serving as an index representing a passage resistance when a predetermined gas passes through the object (partition wall). It is. In the following formula (1), C is permeability (μm ² ), F is gas flow rate (cm ³ / s), T is sample thickness (cm), and V is gas viscosity (dynes · sec / cm ² ). , D represents the sample diameter (cm), and P represents the gas pressure (PSI). Moreover, the numerical value in following formula (1) is 13.839 (PSI) = 1 (atm), and 68947.6 (dynes / cm < ² >) = 1 (PSI). However, “68947.6” in the formula (1) indicates a value of “(dynes / cm ² ) per 1 (PSI)”. “68947.6” has a unit of “(dynes / cm ² ) / PSI”.
Formula (1): C = 10 ⁸ × ⁸ FTV / [{πD ² (P ² −13.839 ² ) /13.839} × 68947.6]

  As a procedure for measuring the permeability, room temperature air was passed through the partition wall 9 of a square plate or a disk-shaped test piece obtained by cutting one of the partition walls 9 so that the remaining rib height was 0.2 mm or less, The passage resistance at that time is measured and obtained by the above formula (1).

  Hereinafter, “other characteristics” of the honeycomb catalyst carrier 50 will be described.

  In the honeycomb catalyst carrier 50, the cross-sectional shape of the cell 7 in the cross section perpendicular to the Z direction is not particularly limited, and for example, a polygonal shape such as a triangle, a quadrangle, a hexagon, an octagon, a circle, an ellipse, or the like. It can be.

  As a material of the partition wall 9, ceramic is preferable. Among ceramics, at least one selected from the group consisting of cordierite, silicon carbide, silicon-silicon carbide based composite material, mullite, alumina, aluminum titanate, silicon nitride, and silicon carbide-cordierite based composite material. Further preferred. By using these materials, it becomes excellent in strength and heat resistance. Further, the partition wall 9 includes at least one selected from the group consisting of cordierite, silicon carbide, silicon-silicon carbide based composite material, mullite, alumina, aluminum titanate, silicon nitride, and silicon carbide-cordierite based composite material. More preferably, it is formed from a ceramic material contained as a main component. Among these, the ceramic partition wall 9 containing cordierite as a main component is most preferable. When cordierite is used as the material of the partition walls 9, a honeycomb catalyst carrier 50 having a small thermal expansion coefficient and excellent thermal shock resistance is obtained. In the present specification, the term “main component” means containing 50% by mass or more of the whole. For example, “having cordierite as a main component” means that the partition wall 9 contains 50% by mass or more of cordierite. The “silicon-silicon carbide based composite material” is formed using silicon carbide (SiC) as an aggregate and silicon (Si) as a binder.

  In the honeycomb catalyst carrier 50, the outer periphery is preferably surrounded by the outer peripheral wall 17 from the viewpoint of increasing the structural strength. Although the thickness of the outer peripheral wall 17 is not specifically limited, 50-4000 micrometers is preferable. In the case where the thickness of the outer peripheral wall 17 is within the above range, an increase in pressure loss can be prevented while maintaining the strength of the honeycomb catalyst carrier 50 appropriately.

  In the honeycomb catalyst carrier 50, the material of the outer peripheral wall 17 is preferably the same as that of the partition walls 9, but may be different.

  In the honeycomb catalyst carrier 50, the shape of the outer peripheral wall 17 is not particularly limited. As for the shape of the outer peripheral wall 17, the cylindrical shape shown in FIG. 1, the cylindrical shape in which the cross-sectional shape perpendicular to the Z direction is elliptical, the cross-sectional shape perpendicular to the Z direction is square, pentagonal, hexagonal It may be a polygonal cylindrical shape or the like.

  The honeycomb catalyst carrier 50 preferably has a length H in the Z direction of 70 to 220 mm, and more preferably 100 to 180 mm. By setting it as the said range, it can ensure in the range of the minimum space required for purification | cleaning of the exhaust gas from various engines.

  The honeycomb catalyst carrier 50 preferably has a width W in the cross section perpendicular to the Z direction of 80 to 350 mm, and more preferably 100 to 330 mm. By setting it as the said range, it can ensure in the range of the minimum space required for purification | cleaning of the exhaust gas from various engines.

  The honeycomb catalyst carrier 50 preferably has a value of “length H / width W” of 0.1 to 3.0, and more preferably 0.1 to 2.0. By setting it as the said range, a ring crack can be suppressed.

2. Manufacturing method of honeycomb catalyst carrier:
Next, a method for manufacturing the honeycomb catalyst carrier of the present embodiment will be described. In the manufacturing method of this embodiment, a honeycomb catalyst carrier is obtained by sequentially performing a clay preparation step, a forming step, and a firing step. The clay preparation step is a step of obtaining a clay by mixing and kneading molding raw materials containing ceramic raw materials. The forming step is a step of obtaining a honeycomb formed body in which a plurality of cells are formed by extruding the clay obtained in the clay preparation step into a honeycomb shape. The firing step is a step of firing the honeycomb formed body to obtain a honeycomb catalyst carrier.

2-1. Clay preparation process:
In the clay preparation step, a molding raw material containing a ceramic raw material is mixed and kneaded to obtain a clay.

  The ceramic raw material is selected from the group consisting of cordierite forming raw material, mullite, alumina, spinel, silicon carbide-cordierite composite material, silicon carbide, silicon-silicon carbide composite material, lithium aluminum silicate, and aluminum titanate. It is preferable that there is at least one. Among the ceramic raw materials listed here, cordierite forming raw materials are preferable. When a cordierite forming raw material is used, a honeycomb structure having a small thermal expansion coefficient and excellent thermal shock resistance can be obtained. The “silicon-silicon carbide based composite material” is formed using silicon carbide (SiC) as an aggregate and silicon (Si) as a binder. "Cordierite raw material" is a ceramic raw material blended to have a chemical composition that falls within the range of 42 to 56 mass% silica, 30 to 45 mass% alumina, and 12 to 16 mass% magnesia. It is fired to become cordierite.

  In the case of a cordierite-forming raw material containing alumina, silica, kaolin, and talc, the average particle diameter of alumina is 0.5 to 10 μm, the average particle diameter of silica is 0.5 to 27 μm, and the average particle diameter of kaolin is It is preferable that the average particle diameter of talc is 1.0-18 μm and 4.0-18 μm. When the average particle size of alumina, silica, kaolin, and talc contained in the cordierite forming raw material is within the above range, pores of an appropriate size are formed due to a reaction such as talc or silica during firing. It becomes easy to form the partition in which (II) exists. Further, in the cordierite forming raw material, the average particle diameter of alumina is 3.0 to 8.0 μm, the average particle diameter of silica is 2.0 to 7.0 μm, the average particle diameter of kaolin is 1.5 to 8.0 μm, And it is more preferable that the average particle diameter of a talc is 7.0-16 micrometers.

In the present specification, the “average particle size” is measured by a laser diffraction / scattering particle size measuring apparatus (for example, trade name “LA-920” (manufactured by Horiba, Ltd.)) based on the light scattering method. The value of 50% particle size.

  In the manufacturing method of the present embodiment, the forming raw material may include a pore former in addition to the ceramic raw material. In particular, a pore former having an average particle size of 30 to 150 μm is preferably used. By using a pore-forming material having an average particle size of 30 to 150 μm, it becomes easy to form a partition wall having a peak (I) in the “pore diameter distribution measured by mercury porosimetry”.

  Furthermore, the average particle diameter of the pore former is most preferably 30 to 120 μm.

  As the pore former, starch, foamed resin, water absorbent resin, silica gel or the like can be usually used.

  The forming raw material may contain a dispersion medium, an additive, and the like.

  Examples of the dispersion medium include water. Examples of the additive include an organic binder and a surfactant. It is preferable that content of a dispersion medium is 30-150 mass parts with respect to 100 mass parts of ceramic raw materials.

  Examples of the organic binder include methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. Among these, it is preferable to use methyl cellulose and hydroxypropoxyl cellulose in combination. It is preferable that content of an organic binder is 1-10 mass parts with respect to 100 mass parts of ceramic raw materials.

  As the surfactant, ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like can be used. These surfactants may be used individually by 1 type, and may be used in combination of 2 or more type. It is preferable that content of surfactant is 0.1-5.0 mass parts with respect to 100 mass parts of ceramic raw materials.

  In the kneaded material preparing step, the method of kneading the forming raw material to form the kneaded material is not particularly limited, and examples thereof include a method using a kneader, a vacuum kneader or the like.

2-2. Molding process:
In the forming step, the clay obtained in the clay preparation step is extruded into a honeycomb shape to obtain a honeycomb formed body. In this honeycomb formed body, a plurality of cells penetrating the honeycomb formed body are formed. Extrusion can be performed using a die. With respect to the die, the slit shape, slit width, pin density, and the like may be appropriately designed in accordance with the cell shape, the shape of the intersecting portion of the partition walls, the partition wall thickness, and the cell density in the honeycomb molded body. As the material of the die, a cemented carbide which does not easily wear is preferable.

2-3. Firing process:
In the firing step, the honeycomb formed body obtained in the above-described forming step is fired to obtain a honeycomb catalyst carrier. The honeycomb catalyst carrier thus obtained includes porous partition walls that define a plurality of cells serving as fluid flow paths.

  In the firing step of the manufacturing method of the present embodiment, the firing temperature can be appropriately determined depending on the material of the honeycomb formed body. For example, when the material of the honeycomb formed body is cordierite, the firing temperature is preferably 1380 to 1450 ° C, and more preferably 1400 to 1440 ° C. The firing time is preferably about 3 to 10 hours.

  In the manufacturing method of the present embodiment, the honeycomb formed body may be dried before firing. The drying method is not particularly limited, and examples thereof include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying. Among these, it is preferable to perform dielectric drying, microwave drying, or hot air drying alone or in combination.

3. Catalyst loading method:
With respect to the honeycomb catalyst carrier obtained by the above manufacturing method, a honeycomb catalyst body can be obtained by using the catalyst supporting method described below.

  FIG. 5 is a schematic diagram showing an outline of the catalyst supporting method of the present embodiment.

  First, the sheet 30 is attached to the first end surface 3 and the second end surface 5 of the honeycomb catalyst carrier 50. Next, a hole 33 is opened at a position where an opening of a predetermined cell 7 exists on the sheet 30 attached to each of the first end face 3 and the second end face 5 (masking step). For example, an adhesive polymer film can be used as the sheet 30 and the holes 33 can be opened using a laser.

  In the catalyst carrying method of the present embodiment, the holes 33 are formed at positions where the openings of the predetermined cells 7 exist in the sheet 30 attached to the first end surface 3 and the second end surface 5 by the following method. First, with respect to the first end surface 3, the cell 7 (hereinafter referred to as “the first end surface 3”) is formed with holes 33 in the sheet 30 every other opening (for skipping one), and the opening on the first end surface 3 side is opened. The first cells 21 ") and the cells 7 whose openings on the first end face 3 side are completely masked by the sheet 30 (hereinafter" second cells 23 ") are arranged alternately. . Next, holes 33 are formed in the sheet 30 only at positions where the openings of the second cells 23 exist on the second end surface 5. As a result, the first cell 21 in which the hole 33 is opened in the sheet 30 only at the opening on the first end face 3 side, and the hole 33 in the sheet 30 is opened only in the opening on the second end face 5 side. The two cells 23 are arranged alternately.

  Subsequently, the catalyst slurry is press-fitted from the first end face 3 and simultaneously sucked from the second end face 5 (catalyst slurry injection process). At this time, on the first end face 3, the opening is opened only by the first cell 21, so the catalyst slurry first flows into the first cell 21. However, in the first cell 21, the opening on the second end face 5 side is covered with the sheet 30. However, a suction force acts on the catalyst slurry in a direction in which the partition wall 9 is passed from the first cell 21 to the second cell 23 by suction from the second end face 5. Therefore, the catalyst slurry enters the pores of the partition wall 9 from the first cell 21. At this time, as described above, the catalyst slurry is mainly filled in the pores 11 constituting the first pore group, and the moisture in the catalyst slurry is transferred from the pores 15 constituting the second pore group to the second cell. Go out to 23. As a result, the catalyst containing zeolite can be sufficiently introduced into the deep pores of the partition wall 9. Unlike the above, in the state shown in FIG. 5, the catalyst slurry injection step may be performed in such a manner that the catalyst slurry is press-fitted from the second end surface 5 and simultaneously sucked from the first end surface 3.

  In addition, what is necessary is just to prepare a catalyst slurry by the conventional method used when carrying | supporting the catalyst containing a zeolite.

  After the above-described catalyst slurry injection step, the honeycomb catalyst carrier 50 into which the catalyst slurry has been injected is dried and fired. In this way, a honeycomb catalyst body can be manufactured. Drying conditions can be 110-180 degreeC and 10-50 minutes. Firing conditions can be 400 to 650 ° C. and 1 to 5 hours.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

(Example 1)
(Preparation of honeycomb structure)
As the cordierite forming raw material, alumina, aluminum hydroxide, kaolin, talc, and silica were used (details of the cordierite forming raw material are shown in Table 1). 100 parts by mass of the cordierite forming material, 2.5 parts by mass of a pore former having an average particle size of 100 μm, 62 parts by mass of water (dispersion medium), 5.6 parts by mass of methyl cellulose (organic binder), and 0.5% of a surfactant Part by weight was added. Thereafter, mixing and further kneading were performed to obtain a clay.

  Next, the kneaded material was extruded using a predetermined mold to obtain a honeycomb formed body. In the honeycomb formed body, square cells were formed in a cross section perpendicular to the cell extending direction, and the overall shape was a columnar shape. The obtained honeycomb formed body was dried with a microwave dryer. Thereafter, it was further completely dried with a hot air dryer. Subsequently, both end faces of the dried honeycomb formed body were cut and adjusted to predetermined dimensions.

  The honeycomb molded body thus obtained was further fired at 1410 to 1440 ° C. for 5 hours to obtain a honeycomb catalyst carrier.

The obtained honeycomb catalyst carrier had a diameter of 143.8 mm and a length in the Z direction of 152.4 mm. The partition wall thickness was 160 μm, and the cell density was 50 cells / cm ² .

  “Partition thickness”, “cell density”, “porosity”, “number of peaks (I)”, “position of peaks (I)”, “number of peaks (II)”, “peaks” in the honeycomb structure carrier (Position (II)), “ratio of the pore volume of the first pore group relative to the total pore volume” (“ratio of the first pore group” in Table 2), “second fine volume relative to the total pore volume” “Percentage of pore volume of pore group” (“Percentage of second pore group” in Table 2), “Permeability”, “Zeolite filling rate into pores”, “Pressure loss before catalyst coating”, “ Table 2 shows “pressure loss after catalyst coating”, “thickness of partition wall after catalyst coating”, and “increase rate of pressure loss by catalyst coating”.

(Preparation of honeycomb catalyst body)
To 200 g of β-zeolite having an average particle size of 4.1 μm, 800 g of water and 1.5 g of a dispersant (this time sodium hexametaphosphate) were added, and wet-crushed by a ball mill. 20 g of alumina sol (the solid content in the alumina sol was 20 wt%) was added to the obtained crushed particles as a binder to obtain a catalyst slurry. This catalyst slurry was prepared to have a viscosity of 3 mPa · s. And the catalyst slurry injection | pouring process was implemented by the method shown in FIG. Excess slurry was removed with compressed air, dried at 120 ° C. for 20 minutes, and calcined at 450 ° C. for 1 hour. Thus, a honeycomb catalyst body was obtained.

(Examples 2 to 4)
The honeycomb catalyst carriers of Examples 2 to 4 were manufactured in the same manner as Example 1 except that the conditions were as shown in Tables 1 and 2.

(Comparative Examples 1-3)
The honeycomb catalyst carriers of Comparative Examples 1 to 3 were produced in the same manner as in Example 1 except that the conditions were as shown in Tables 1 and 2.

[Porosity (%)]
The porosity (%) in the honeycomb catalyst carrier was measured by a mercury porosimeter (mercury intrusion method). As the mercury porosimeter, the product name: Auto Pore III Model 9405 manufactured by Micromeritics was used.

[Pore size distribution]
The pore size distribution in the honeycomb catalyst carrier was measured by a mercury porosimeter (mercury intrusion method). As the mercury porosimeter, the product name: Auto Pore III Model 9405 manufactured by Micromeritics was used. The frequency (%) on the vertical axis in the graph is represented by (100 × log differential pore volume) / total pore volume.

[Pore volume]
The log differential pore volume (cc / g) in the honeycomb catalyst carrier was measured by a mercury porosimeter (mercury intrusion method). As the mercury porosimeter, the product name: Auto Pore III Model 9405 manufactured by Micromeritics was used.

[Thickness of partition wall]
The thickness of the partition wall before catalyst support (catalyst support) was measured by an image analyzer (trade name “NEXIV, VMR-1515” manufactured by Nikon Corporation). The partition wall thickness after catalyst loading (catalyst body) (the partition wall thickness after catalyst coating) was calculated according to the method described in the calculation method of [pressure loss] described later.

[Permeability]
The permeability of the partition walls in the honeycomb catalyst carrier was measured with a palm porometer. As the palm porometer, a product name: Capillary Flow Porometer model CPF1100AEX manufactured by Porous Materials was used.

[Compressive strength]
The compressive strength of the honeycomb catalyst support was measured by a dual column desktop universal test system. As a dual column desktop universal testing system, model 5569 manufactured by INSTRON was used. The compressive strength conforms to JASO M 505-87, and a cylindrical test piece having a length of 25.4 mm in the Z-axis direction and a diameter of 25.4 mm perpendicular to the Z-axis direction is pierced from the honeycomb structure. This means the value measured by the tabletop universal testing system for the compressive strength in the Z-axis direction.

[Filling rate]
The filling rate of the catalyst into the pores of the partition walls in the honeycomb catalyst body was measured by two-dimensional image analysis software. The image was taken with a scanning electron microscope S-3400N manufactured by HITACHI on an area of 1.3 mm × 1.0 mm with respect to a cross section perpendicular to the thickness direction of the partition wall. The photographed image was analyzed using a two-dimensional image analysis software WinROOF manufactured by Mitani Corporation. Specifically, the ratio of each color of voids, partition walls, and zeolite having different shades after image binarization processing is calculated in the partition wall portion with the partition wall surface as a boundary at three locations, and the filling rate at each location is calculated based on the ratio. Was measured. The average value was calculated from the filling rate at each location (total of 3 locations). Table 2 shows the average filling rate.
(Zeolite filling ratio / partition pore ratio) × 100 = filling ratio

[Pressure loss]
The pressure loss was calculated according to the method described in JP-A-2005-337086. The pressure loss in the honeycomb catalyst carrier (before catalyst coating) is a sample having a diameter of 25.4 mm and a length of 70 mm, under the conditions of an inlet temperature of 25 ° C., 101325.0 Pa, and a wind speed of 2 m ³ / min. It calculated according to. In addition, the calculation of the pressure loss in the honeycomb catalyst body (after the catalyst coating) was performed after calculating the thickness of the zeolite layer deposited on the surface of the partition walls as follows. First, the honeycomb catalyst carrier was cut out so that the diameter was 25.4 mm and the length in the cell extending direction was 70 mm, and the zeolite loading was set to 200 g / L. The “zeolite amount filled in the pores (i)” was determined from the pore filling rate, and the difference from the total supported amount of zeolite was defined as “the amount of zeolite deposited on the surface of the partition wall (ii)”. The thickness of the zeolite layer deposited on the surface of the partition wall was determined from the zeolite bulk density of 0.6 g / cc, and the thickness of the partition wall before catalyst support was added to the thickness of the partition wall before catalyst support. As in the case of calculating the pressure loss in the honeycomb catalyst carrier (before catalyst coating), the sample was subjected to pressure according to Japanese Patent Application Laid-Open No. 2005-337086 under conditions of an inlet temperature of 25 ° C., 101325.0 Pa, and a wind speed of 2 m ³ / min. Loss was calculated. Note that the bulk density of the above zeolite was determined by placing the above catalyst slurry in a magnetic crucible having a diameter of 79 mm and a height of 25 mm, drying at 120 ° C. for 20 minutes, and at 450 ° C. for 1 hour. Calculation was performed based on the size and weight of the fired body obtained after firing.

[Discussion]
When Examples 1-4 and Comparative Examples 1-3 were compared, when the porosity was comparable, the Example obtained the result that permeability and compressive strength became large compared with the comparative example. From this result, the honeycomb catalyst carriers of Examples 1 to 4 have more continuous air holes than the honeycomb catalyst carriers of Comparative Examples 1 to 3, and therefore, moisture easily passes through the partition walls in the step of supporting the catalyst. The catalyst was thought to be easily filled into the pores. Further, since the honeycomb catalyst carriers of Examples 1 to 4 have higher compressive strength than the honeycomb catalyst carriers of Comparative Examples 1 and 2, the honeycomb catalyst carriers are stored (canned) while being pressed into the can body. Enough strength.

  Further, when Examples 1 to 4 and Comparative Examples 1 to 3 were compared, the results were higher in the catalyst in the pores of the partition walls than in the comparative example. From this result, it was found that the honeycomb catalyst carriers of Examples 1 to 4 were easier to fill the pores with the catalyst than the honeycomb catalyst carriers of Comparative Examples 1 to 3.

  Comparing the pressure loss before and after the catalyst coating in Examples 1 to 4 and Comparative Examples 1 to 3, when the partition wall thickness and cell density are equivalent (Examples 1 and 2, Comparative Examples 1, 2, and Examples 3, 4 And Comparative Example 3) It was found that the pressure loss before catalyst coating showed the same value in the Example and Comparative Example, whereas the pressure loss after catalyst coating was generally lower in the Example. As for the value of the rate of increase in pressure loss due to the catalyst coating, it was clearly found that Examples 1-4 were smaller than Comparative Examples 1-3.

  From the above results, it was found that the honeycomb catalyst carrier of the present invention can reduce the thickness of the catalyst layer deposited on the partition wall surface by filling the catalyst in the pores of the partition walls.

The present invention can be used as a honeycomb catalyst carrier for carrying available zeolite to selective catalytic reduction of NO _X (SCR).

3: 1st end surface, 5: 2nd end surface, 7: Cell, 9: Partition, 11: Pore (composing 1st pore group), 15: Pore (composing 2nd pore group), 17: outer peripheral wall, 21: first cell, 23: second cell, 30: sheet, 33: hole of (sheet), 50: honeycomb catalyst carrier.

Claims (4)

A porous partition wall that partitions and forms a plurality of cells serving as fluid flow paths,
The partition wall has a porosity of 40% or more,
In the pore size distribution measured by the mercury intrusion method of the partition wall,
Those having a pore diameter in the range of 15 μm to 300 μm are defined as the first pore group,
Those having a pore diameter in the range of 1 μm or more and less than 15 μm are defined as the second pore group,
In the range of the pore diameter of 15 to 300 μm including the first pore group, there is at least one peak (I) of the pore diameter distribution,
At least one peak (II) of the pore size distribution is present in the range of the pore size including the second pore group of 1 μm or more and less than 15 μm,
The pore volume of the first pore group is 50 to 80% of the total pore volume;
The pore volume of the second pores group Ri 20-50% der of the total pore volume,
At least one of the peaks (I) is present in the pore diameter range of 20 to 80 μm,
A honeycomb catalyst carrier in which at least one of the peaks (II) is present in a pore diameter range of 6.2 µm or more and less than 15 µm . The honeycomb catalyst carrier according to claim 1, wherein the partition walls have a thickness of 50 to 350 µm. The honeycomb catalyst carrier according to claim 1 or 2 cell density of 45 to 200 pieces / cm ^2. The honeycomb catalyst carrier according to any one of claims 1 to 3 , wherein the partition wall has a permeability of 0.5 to 6.0 µm ² .

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