JP2012030219A - Honeycomb structure and gas treatment apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb structure causing few cracks even if incineration removal of collected fine particles is frequently repeated, and a gas treatment apparatus increasing in long term reliability by using the honeycomb structure.SOLUTION: The honeycomb structure causing few cracks includes a cylindrical part 5 and a partition part 2 lattice-likely disposed inside the cylindrical part 5 so as to provide a plurality of flow holes. The plurality of the flow holes have first flow holes 16 and second flow holes 17 respectively disposed in rows from the inner side toward the outer side of the cylindrical part 5 and having different opened diameters. Third flow holes 18 having curved faces facing the cylindrical part 5 are provided on the extended lines of the disposing direction of the first flow holes 16 having a larger opened diameter. Thus, the honeycomb structure causing few cracks can be provided.

Description

  The present invention relates to a honeycomb structure used for a filter or the like for purifying exhaust gas, and a gas processing apparatus including the honeycomb structure.

  Conventionally, a filter has been used to collect fine particles contained in exhaust gas generated from an internal combustion engine, an incinerator, a boiler, and the like.

  Such a filter is surrounded by a cylindrical portion through which a fluid flows, a lattice-shaped partition wall having air permeability disposed inside the cylindrical portion, and the partition wall portion, and both ends are sealed alternately. A honeycomb structure having a plurality of flow holes that are stopped and become fluid inflow paths and outflow paths is used.

Then, as a method of regenerating the honeycomb structure in which the collected fine particles and the like are accumulated, for example, a method of burning and removing the fine particles by heating to 600 ° C. or higher, or an oxidation catalyst on the exhaust gas inflow side of the honeycomb structure. There is a method in which fine particles are burned and removed using heat generated by an oxidation reaction that is generated by supplying a fuel such as light oil to the oxidation catalyst.

  However, when the honeycomb structure is regenerated by these methods, thermal stress is generated in the honeycomb structure, and the honeycomb structure may be cracked or melted.

  Various honeycomb structures for preventing such cracks and melting damage have been proposed. For example, in Patent Document 1, a columnar honeycomb structure in which a large number of flow holes are arranged in parallel in the longitudinal direction across a partition wall, and the large number of flow holes has a total area of cross sections perpendicular to the longitudinal direction. A large-capacity through hole group in which one end is sealed so as to be relatively large, and a small one in which the other end is sealed so that the sum of the cross-sectional areas is relatively small. A honeycomb structure that includes a group of volumetric through-holes and includes a plurality of columnar porous ceramic members has been proposed.

International Publication No. 2004/024293 Pamphlet

  However, in the columnar porous ceramic member constituting the conventional honeycomb structure proposed in Patent Document 1, the cross-sectional shapes are all quadrangular or octagonal flow holes are alternately arranged. There is a difference in stress concentrated between the cylindrical part on the extension line of the flow hole and the cylindrical part on the extension line of the octagonal flow hole, and the honeycomb structure is easily distorted and cracks are easily generated. As a starting point, there was a problem of being easily damaged.

  The present invention has been devised to solve the above problems, and a honeycomb structure that is less likely to cause cracking and can maintain high strength even when the collected fine particles are frequently burned and removed, and the honeycomb structure. It aims at providing a gas processing apparatus provided with.

The honeycomb structure of the present invention includes a cylindrical portion and partition walls arranged in a lattice shape so as to provide a plurality of flow holes inside the cylindrical portion, and the plurality of flow holes include the above-described flow holes. The first flow hole having a first flow hole and a second flow hole having different opening diameters arranged in a row from the inner side toward the outer side inside the cylindrical part, and having a large opening diameter A third flow hole having a curved surface facing the cylindrical portion is provided on an extension line in the arrangement direction.

  The gas treatment device of the present invention is characterized by including the honeycomb structure having the above-described configuration.

  The honeycomb structure of the present invention includes a cylindrical portion and partition walls arranged in a lattice shape so as to provide a plurality of flow holes inside the cylindrical portion, and the plurality of flow holes include the above-described flow holes. The first flow hole having a first flow hole and a second flow hole having different opening diameters arranged in a row from the inner side toward the outer side inside the cylindrical part, and having a large opening diameter Since the third flow hole having a curved surface facing the cylindrical portion is provided on the extension line in the arrangement direction, the cylinder located on the extension line in the arrangement direction of the first flow hole having a large opening diameter Since the stress generated in the cylindrical portion can be relieved, the difference between the stress generated in the cylindrical portion located on the extension line in the arrangement direction of the second flow holes having a small opening diameter can be reduced, and the cylindrical portion In addition to suppressing the occurrence of cracks in the honeycomb structure, the strength of the honeycomb structure can be maintained high.

  Moreover, according to the gas treatment device of the present invention, since the honeycomb structure of the present invention that can suppress the occurrence of cracks is provided, long-term reliability can be improved.

An example of the honeycomb structure of the present embodiment is shown. (A) is a perspective view, and (b) is a cross-sectional view taken along line B-B ′ in (a). FIG. 2 is a partially enlarged view of a cross section taken along line C-C ′ in (a) of the honeycomb structure of the example shown in FIG. 1. It is a fragmentary sectional view in a section perpendicular to the direction through which fluid flows showing other examples of a honeycomb structure of this embodiment. FIG. 10 is a partial cross-sectional view in a cross section perpendicular to the direction in which a fluid flows, showing still another example of the honeycomb structure of the present embodiment. FIG. 10 is a partial cross-sectional view in a cross section perpendicular to the direction in which a fluid flows, showing still another example of the honeycomb structure of the present embodiment. FIG. 10 is a partial cross-sectional view in a cross section perpendicular to the direction in which a fluid flows, showing still another example of the honeycomb structure of the present embodiment. It is a schematic sectional drawing of the gas treatment apparatus which shows an example of this embodiment typically.

  Hereinafter, an example of the honeycomb structure of the present embodiment and a gas processing apparatus using the honeycomb structure will be described.

  FIG. 1 shows an example of the honeycomb structure of the present embodiment, in which (a) is a perspective view and (b) is a cross-sectional view taken along line B-B ′ in (a).

  The honeycomb structure 11 includes a tubular portion 5 through which a fluid flows, a partition wall portion 2 that is arranged in a lattice shape so as to provide a plurality of flow holes inside the tubular portion 5, and has air permeability. 2 are provided with a plurality of flow holes that become an inflow path 3 and an outflow path 4 surrounded by 2. In addition, the flow hole which becomes the inflow path 3 and the outflow path 4 is sealed with the sealing material 9 alternately at one end and the other end of the honeycomb structure 11 respectively. Thereby, the fluid flowing inside the cylindrical portion 5 flows in the direction indicated by A shown in FIG. 1 (hereinafter, the direction in which the fluid flows is also simply referred to as the axial direction A).

  FIG. 2 is a partially enlarged view of a cross section taken along line C-C ′ in (a) of the honeycomb structure of the example shown in FIG. 1.

  In the honeycomb structure 11 shown in FIG. 2, the shape of the inflow passage 3 is an octagonal shape and the shape of the outflow passage 4 is a square shape in a cross section perpendicular to the axial direction A (hereinafter also simply referred to as a cross section). In the present embodiment, the opening diameter of the revenue path 3 is larger than the opening diameter of the outflow path 4, and the inflow path 3 corresponds to a first flow hole having a large opening diameter. It corresponds to a second flow hole having a small opening diameter. In addition, an opening diameter means what converted into the circle equivalent diameter of the opening area of the flow hole which comprises an inflow path and an outflow path.

  Here, in the honeycomb structure 11 shown in FIG. 2, the flow hole 16 having a large opening diameter as the inflow passage 3 and the flow hole 17 having a small opening diameter as the outflow passage 4 are formed from the inside of the tubular portion 5. They are arranged in a row toward the outside. And the flow hole 18 which is the 3rd flow hole which has the curved surface S which faces the cylindrical part 5 on the extension line (it shows by P in FIG. 2) of the flow hole 16 is the arrangement direction of the flow hole 17. On the extended line (indicated by Q in FIG. 2), a flow hole 19 which is a fourth flow hole is provided. The extension line in the arrangement direction of the flow holes 16 means an extension line of a line connecting the center portions of the flow holes 16, and when this line is not a straight line, it can be an approximate line. It is also agreed on the extension line of the circulation hole 17.

Here, a curved surface having the flow hole 18, an example is shown of a curved surface that continuously changes from the surface S ₁ of the cylindrical portion 5 toward the surface S ₂ of the partition wall 2, for example, corners of the circulation hole 16 only May be a curved surface, and the entire surface of the flow hole 18 facing the cylindrical portion 5 may be a curved surface.

  As a result, since the surface of the flow hole 18 facing the cylindrical part 5 is a curved surface, the stress generated in the cylindrical part 5 in contact with the flow hole 18 is easily dispersed and the flow holes 16 are extended in the arrangement direction. Since the stress generated in the cylindrical portion 5 positioned on the line P can be relaxed, the difference from the stress generated in the cylindrical portion 5 positioned on the extension line Q in the arrangement direction of the flow holes 17 is reduced. Thereby, the honeycomb structure 11 can suppress the distortion of the cylindrical portion 5, and the cylindrical portion 5 is hardly cracked, and the strength can be maintained high.

  In addition, the flow hole 19 positioned on the extension line Q of the flow hole 17 having a small opening diameter may have a curved surface facing the tubular portion 5. In the honeycomb structure 11 shown in FIG. An example in which the hole 19 has a curved surface S ′ facing the cylindrical portion 5 is shown.

  In this case, the length of the curved surface in the circulation hole 18 is preferably longer than the length of the curved surface in the circulation hole 19. Thereby, the difference between the stress generated in the cylindrical portion 5 positioned on the extension line P in the arrangement direction of the flow holes 16 and the stress generated in the cylindrical portion 5 positioned on the extension line Q in the arrangement direction of the flow holes 17. However, the stress generated in the cylindrical portion 5 in contact with the flow hole 19 can be reduced, cracks are unlikely to occur in the cylindrical portion 5, and the strength can be maintained high. The length of the curved surface can be obtained, for example, by analyzing an image obtained by photographing the honeycomb structure 11 using image software.

Note that the length of the curved surface can be changed by changing the curvature of the curved surface in the circulation holes 18 and 19.

Further, in the above example, a curved surface with the flow hole 18, a continuously varying curved from the surface S ₁ of the cylindrical portion 5 toward the surface S ₂ of the partition wall 2, for example, as shown in FIG. 2 Furthermore, it means that the surface S ₁ and the surface S ₂ are connected so that the inclination of the surface S ₂ approaches the inclination of the surface S _{1 as} it approaches the surface S ₁ . Further, the curvature of the curved surface S continuously changing from the surface S ₁ to the surface S ₂ is, for example, 2 mm ⁻¹ or more and 4 mm ⁻¹ or less, and as the surface S ₂ approaches the surface S ₁ , the curvature becomes It is preferable that it is small.

Further, the curved surface S 'with the flow hole 19 in FIG. 2, the surface of the surface S ₃ of the tubular portion _5, when the surface of the partition wall 2 and the surface S _4, the partition wall portion from the surface S ₃ of the tubular portion 5 Although over the second surface S ₄ shows an example of a continuously varying curved surface, for example, only the corners of the flow hole 19 may have a curved surface, the entire surface facing the tubular portion 5 of the flow hole 19 May be curved.

In this case, the curvature of the curved surface S of the circulation hole 18 is preferably larger than the curvature of the curved surface S ′ of the circulation hole 19. More preferably, the curvature of the curved surface S of the circulation hole 18 should be 4 mm ⁻¹ or more larger than the curvature of the curved surface S ′ of the circulation hole 19. Thus, if the curvature of the curved surface S of the flow hole 18 is 4 mm ⁻¹ or more than the curvature of the curved surface S ′ of the flow hole 19, the number of cracks generated when stress such as thermal stress is generated in the honeycomb structure 11 is reduced. Therefore, the strength of the honeycomb structure 11 can be maintained high.

Here, such a honeycomb structure 11 has, for example, a cylindrical shape having an outer diameter of 140 to 270 mm and a length L in the axial direction A of 100 to 250 mm, and is distributed in a cross section perpendicular to the axial direction A. holes 16 and 17 the number is 5 to 124 per 100mm ² (32~800CPSI). Moreover, the partition part 2 is 0.05 mm or more and 0.25 mm or less in thickness, and the sealing material 9 is 1 mm or more and 5 mm or less in thickness. CPSI stands for Cells Per Square Inches.

  An internal combustion engine (not shown) such as a diesel engine or a gasoline engine is disposed on the inflow side of the honeycomb structure 11, and when this internal combustion engine is operated, exhaust gas that is fluid is generated. This exhaust gas is shown in FIG. ), The inflow side sealing material 9 on the inflow side of the honeycomb structure 11 is introduced from the inflow path 3 where it is not formed, but the outflow is blocked by the sealing material 9. The exhaust gas from which the outflow is blocked passes through the partition wall 2 having air permeability and is introduced into the adjacent outflow passage 4. When the exhaust gas passes through the partition wall 2, the main component is fine particles mainly composed of carbon in the exhaust gas on the wall surfaces of the partition wall 2 and the pores of the partition wall 2, and sulfate formed by oxidation of sulfur. Fine particles such as unburned hydrocarbons (hereinafter collectively referred to simply as “fine particles”) made of fine particles and polymer are collected. The exhaust gas in which the fine particles are collected is discharged to the outside through the outflow passage 4 where the sealing material 9 is not formed in a purified state.

  FIG. 3 is a partial cross-sectional view in a cross section perpendicular to the axial direction A, showing another example of the honeycomb structure of the present embodiment.

  The honeycomb structure 12 is a honeycomb structure in which the surface T on the tubular portion 5 side of the partition wall portion 2 constituting the flow holes 20 and 21 adjacent to the inner sides of the flow holes 18 and 19 is a curved surface.

  In the honeycomb structure 12, when the surface T on the cylindrical portion 5 side of the partition wall 2 constituting the flow holes 20, 21 is a curved surface, the stress generated in the partition wall 2 constituting the flow holes 20, 21 is caused by the stress generated in the flow holes 20. , 21 is easy to disperse on the surface T on the cylindrical part 5 side, so that stress such as thermal stress is generated in the honeycomb structure 12 and the partition part located on the cylindrical part 5 side from the cylindrical part 5 or the flow holes 20, 21. 2 or the like, since the crack is difficult to propagate from the partition wall portion 2 having the surface T on the tubular portion 5 side of the flow holes 20 and 21 to the inner side of the honeycomb structure 12, the honeycomb structure The strength of 12 can be maintained even higher, which is preferable.

  FIG. 4 is a partial cross-sectional view in a cross section perpendicular to the axial direction A, showing still another example of the honeycomb structure of the present embodiment.

  The honeycomb structure 13 is a honeycomb structure in which the flow holes 18 located on the extension line in the arrangement direction of the flow holes 18 are circular in cross section.

  In the honeycomb structure 13, since the stress generated in the tubular portion 5 located on the extension line P tends to be more relaxed when the flow hole 18 is circular, the tubular portion located on the extension line P. 5 and the tubular portion 5 located on the extension line Q are reduced, and the strength of the honeycomb structure 13 can be maintained higher. It is preferable that the flow hole 19 positioned on the extension line Q of the outflow passage 3b and in contact with the cylindrical portion 5 is circular because the strength of the honeycomb structure can be maintained higher. It does not matter. The opening diameter of the flow hole 18 is preferably, for example, 1.5 times or more and 1.9 times or less the opening diameter of the flow hole 19, and the opening diameters of the flow holes 18, 19 'are, for example, equivalent circle diameters, respectively. It is preferably 1.1 mm or more and 1.5 mm or less, and 0.7 mm or more and 0.8 mm or less. .

  FIG. 5 is a partial cross-sectional view in a cross section perpendicular to the axial direction A, showing still another example of the honeycomb structure of the present embodiment.

  The honeycomb structure 14 is a honeycomb structure in which the circulation holes 20 and 21 adjacent to the inner sides of the circulation holes 18 and 19 located in the second region N and in contact with the cylindrical portion 5 are circular. is there.

  In the honeycomb structure 14, since the flow holes 20 and 21 are circular, stress generated in the partition wall portions 2 constituting the flow holes 20 and 21 is easily dispersed, and thus stress such as thermal stress is generated in the honeycomb structure 14. Even if a crack is generated in the partition portion 2 or the like on the tubular portion 5 side from the tubular portion 5 or the flow holes 20 and 21, the crack is difficult to propagate to the first region M side. It is preferable that the strength of can be maintained higher.

  Here, the opening diameters of the flow holes 20 and 21 are, for example, 1.1 mm or more and 1.5 mm or less and 0.7 mm or more and 0.8 mm or less as equivalent circle diameters, respectively.

  FIG. 6 is a partial cross-sectional view in a cross section perpendicular to the axial direction A, showing still another example of the honeycomb structure of the present embodiment.

  In the honeycomb structure 15, in the cross section perpendicular to the axial direction A, the opening areas of the flow holes 18, 19 in contact with the cylindrical portion 5 are the same as the flow holes 20, 21 adjacent to the inner sides of the flow holes 18, 19. A honeycomb structure smaller than the opening area.

  The honeycomb structure 15 tends to increase the isostatic strength of the honeycomb structure 15 when the opening area of the flow holes 18 and 19 is smaller than the opening area of the flow holes 20 and 21 adjacent to the inside thereof. Further, even when heat is applied to the honeycomb structure 15, since it tends to be gradually cooled from the inside toward the outside, the generation of cracks can be suppressed. The opening area of the circulation holes 18, 19, 20, and 21 is obtained by analyzing a copy image obtained by copying the cross section with a copying machine (copy machine) or the like, and obtaining the individual areas of the circulation holes 18, 19, 20, and 21. The opening areas of the flow hole 18 and the flow hole 20, and the flow hole 19 and the flow hole 21 may be compared.

  Here, the opening area of the circulation holes 18 and 19 is preferably 80% or more and 90% or less with respect to the opening area of the corresponding circulation holes 20 and 21.

Moreover, in the honeycomb structure 11-15 of the example shown in FIGS. 1-6, the diameter of the inflow path 3 which is not sealed in the inflow side end surface (IF) is with respect to the diameter of the outflow path 4 which is sealed. Thus, it is preferably 1.55 times or more and 1.95 times or less. Thus, by setting the diameter ratio to 1.55 times or more, the respective surface areas of the partition wall 2 and the sealing material 9 capable of adsorbing the fine particles are increased, so that the amount of collected fine particles can be increased. In addition, when the ratio of the diameters is 1.95 times or less, the partition wall portion 2 is not extremely thinned, so that the mechanical strength is hardly impaired. Here, the diameter of the inflow path 3 and the outflow path 4 is a diameter of an inscribed circle in contact with the partition wall portion 2 on the inflow side end face (IF), and the magnification is, for example, 50 times or more and 100 times or less using an optical microscope. Can be measured as

In addition, the components constituting the partition wall portion 2, the sealing material 9 and the cylindrical portion 5 are components whose main components are all low in linear expansion coefficient, for example, cordierite (2MgO.2Al ₂ O ₃ · 5SiO ₂ ). , Β-eucryptite (Li ₂ O · Al ₂ O ₃ · 2SiO ₂ ), β-spodumene (Li ₂ O · Al ₂ O ₃ · 4SiO ₂ ), silicon carbide (SiC), silicon nitride (Si ₃ N ₄₎ ), sialon _{(Si 6-Z Al Z O} Z N 8-Z, where z is 0.1 or more and 1 or less in amount of solid solution.), mullite _{(3Al 2 O 3 · 2SiO 2} ), calcium aluminate (CaAl ₄ O ₇ ), potassium zirconium phosphate (KZr ₂ (PO ₄ )), and aluminum titanate (Al ₂ TiO ₅ ) are preferred.

Here, each main component of the partition wall part 2, the sealing material 9 and the cylindrical part 5 refers to a component that occupies 50% by mass or more with respect to 100% by mass of the total component constituting each member. Is identified by X
The content can be determined by an ICP emission analysis method or a fluorescent X-ray analysis method.

Moreover, when the partition part 2, the sealing material 9, and the cylindrical part 5 are all composed of aluminum titanate (Al ₂ TiO ₅ ), magnesium titanate (MgTi ₂ O ₅ ) and iron titanate (Fe _2). It is preferable that TiO ₅ ) is contained in an amount of 16% by mass or more and 24% by mass or less, respectively. This ratio is optimal for aluminum titanate (Al ₂ TiO ₅ ) with excellent heat resistance, magnesium titanate (MgTi ₂ O ₅ ) with excellent corrosion resistance and iron titanate (Fe ₂ TiO ₅ ) with excellent heat resistance It is a ratio that improves the heat resistance, corrosion resistance, and heat deterioration resistance of each member.

Further, the partition wall 2, when the sealing material 9 and the cylindrical portion 5 are both mainly composed of aluminum titanate (Al 2 _{TiO 5),} the partition wall 2, each of the sealing material 9 and the cylindrical portion 5 At least one of the grain boundary phases is preferably composed mainly of silicon oxide. When at least one of these grain boundary phases contains silicon oxide as a main component, there is a tendency to strongly bond crystal grains adjacent to the grain boundary phase, and to suppress abnormal grain growth of crystal grains, There is a tendency that the mechanical strength can be increased.

In particular, the silicon oxide is preferably 90% by mass or more with respect to 100% by mass in total of each oxide constituting the grain boundary phase.

This silicon oxide is suitable because silicon dioxide having a composition formula of SiO ₂ is highly stable, but the composition formula is SiO _2-x (where x is 0 <x <2). There is no problem even if the non-stoichiometric silicon oxide shown in FIG.

Further, each grain boundary phase may contain an alkali metal oxide, but the alkali metal oxide has low corrosion resistance against sulfates such as sodium sulfate and calcium sulfate contained in engine oil. Is preferably less, and is preferably 12% by mass or less with respect to 100% by mass of the oxide constituting each grain boundary phase. If the alkali metal oxide is in this range, the partition wall portion 2, the sealing material 9 and the tubular portion 5 are unlikely to lose the corrosion resistance with respect to sulfate.

  In particular, lithium oxide and sodium oxide are more preferably 2% by mass or less with respect to a total of 100% by mass of the oxides constituting the grain boundary phase.

In addition, since aluminum oxide has low resistance to sulfate, it is preferably 15% by mass or less with respect to 100% by mass in total of the oxides constituting each grain boundary phase.

  By the way, in the honeycomb structure 11-15 of this embodiment of the example shown in FIGS. 1-6, the partition part 2 has a porosity of 35 volume% or more and 60 volume% or less, and an average pore diameter is 5 micrometers or more and 26 micrometers or less. It is preferable to consist of a certain porous ceramic sintered body. This is because, when the porosity and average pore diameter of the ceramic sintered body forming such a partition wall portion 2 are in this range, an increase in pressure loss can be suppressed while maintaining the mechanical characteristics. What is necessary is just to obtain | require a pore diameter and a porosity based on the mercury intrusion method.

  Specifically, first, a sample for measuring the average pore diameter and the porosity is cut out from the partition wall 2 so that the mass becomes 0.6 g or more and 0.8 g or less.

  Next, using a mercury intrusion porosimeter, mercury is injected into the pores of the sample, and the pressure applied to the mercury and the volume of mercury that has entered the pores are measured.

  The volume of mercury is equal to the volume of pores, and the following formula (1) (Washburn's relational expression) is established for the pressure applied to mercury and the pore diameter.

d = −4σcos θ / P (1)
Where d: pore diameter (m)
P: Pressure applied to mercury (Pa)
σ: Surface tension of mercury (0.485N / m)
θ: Contact angle between mercury and pore surface (130 °)
From the equation (1), each pore diameter d for each pressure P is obtained, and distribution of each pore diameter d and cumulative pore volume can be derived. Then, the pore diameter (D50) corresponding to 50% of the cumulative pore volume may be the average pore diameter, and the percentage of the cumulative pore volume with respect to the volume of the sample may be the porosity.

  FIG. 7 is a schematic cross-sectional view of a gas processing apparatus schematically showing an example of this embodiment.

  The gas processing apparatus 10 includes the honeycomb structure 11 of the present embodiment in which a catalyst (not shown) is supported on the wall surface of the partition wall portion 2, and has an end that is not sealed with a flow hole as an inlet. A gas processing device that collects particulates in the exhaust gas (EG) by the partition wall 2 by allowing the exhaust gas (EG) to pass through the other end of the other through hole 2 that is not sealed as an outlet. is there. The honeycomb structure 11 is accommodated in the case 7 with its outer periphery held by the heat insulating material layer 6, and the heat insulating material layer 6 is formed of at least one of ceramic fiber, glass fiber, carbon fiber, and ceramic whisker, for example. ing.

The case 7 is made of, for example, stainless steel such as SUS303, SUS304, and SUS316. The case 7 has a central portion formed in a cylindrical shape and both end portions formed in a truncated cone shape, and exhaust gas (EG) is supplied. Exhaust pipes 8a and 8b are connected to the inflow port 7a and the outflow port 7b from which exhaust gas (EG) is discharged, respectively.

When the diesel engine (not shown) is connected to the inflow side of the gas processing apparatus 10 and the diesel engine is operated and exhaust gas (EG) is supplied from the exhaust pipe 8a to the case 7, the honeycomb Exhaust gas (EG) is introduced into the inflow passage 3 where the sealing material 9 on the inflow side of the structure 11 is not formed, but the outflow is blocked by the sealing material 9 formed on the outflow side. . Exhaust gas (EG) whose outflow is blocked passes through the partition wall 2 having air permeability and is introduced into the adjacent outflow path 4. When the exhaust gas (EG) passes through the partition wall 2, fine particles in the exhaust gas (EG) are collected on the wall surface of the partition wall 2 and the surface of the pores of the partition wall 2. The exhaust gas (EG) in which the fine particles are collected is discharged to the outside through the exhaust pipe 8b from the outflow passage 4 where the sealing material 9 is not formed in a purified state.

  In such a gas processing apparatus 10, the catalyst supported on the wall surface of the partition wall 2 is, for example, a platinum group metal such as ruthenium, rhodium, palladium, iridium, platinum and the oxide thereof, gold, silver, copper or the like. It consists of at least one of group 11 metal and vanadium oxide, and when gas such as gas oil is vaporized, fine particles in the exhaust gas collected by the partition wall 2 are oxidized. Burn. In particular, when a Group 11 metal of the periodic table such as gold, silver, or copper is selected, it is preferable that the particles are fine particles of nanometer level.

  Further, in order to increase the contact area between the catalyst supported on the wall surface and the exhaust gas, it is preferable to support a powder having a large specific surface area such as γ alumina, δ alumina, and θ alumina on the wall surface of the partition wall 2. is there.

  In the honeycomb structures 11 to 15 of the present embodiment, as described above, when the catalyst is supported on the wall surface of the partition wall 2, the particulates are easily burned and removed at a low temperature. And cracks are less likely to occur. Furthermore, it is preferable that the catalyst is supported not only on the wall surface but also on the surface of the pores of the partition wall 2.

  Further, ZSM-5, ZSM-11, ZSM-12, and ZSM-18 are catalysts for storing and reducing nitrogen oxides (NOx) together with a catalyst for oxidizing and burning fine particles in exhaust gas. , ZSM-23, MCM zeolite, mordenite, faujasite, ferrierite, and zeolite beta may be supported on at least one of the wall surface of the partition wall 2 and the surface of the pores of the partition wall 2.

  For example, when the gas processing apparatus 10 of the present embodiment includes the honeycomb structure 11 that is an example of the present embodiment, cracks are less likely to occur in the honeycomb structure 11, so long-term reliability is ensured. It can be improved.

  Note that the gas treatment device 10 of the present embodiment has been described as described above for the case where the honeycomb structure 11 of the present embodiment is provided, but instead of the honeycomb structure 11, any of the honeycomb structures 12 to 15 can be used. It goes without saying that may be used.

  Further, in the present embodiment, the example using the exhaust gas in which the fluid is a gas has been described, but it is also possible to use a liquid as the fluid. For example, it is possible to use clean water or sewage as the fluid, and the gas treatment device of the present embodiment can also be applied for liquid filtration.

  Next, an example of a method for manufacturing the honeycomb structures 11 to 15 will be described.

In order to obtain honeycomb structures 11 to 15 made of a ceramic sintered body in which the main components of the partition wall portion 2, the sealing material 9 and the cylindrical portion 5 are all aluminum titanate, first, aluminum oxide powder is added to 27 ~ 33% by mass, ferric oxide powder 13-17% by mass, magnesium oxide powder 7-13% by mass and the balance prepared as titanium oxide powder with water, acetone or 2-propanol To obtain a primary raw material. Here, it is preferable to use a high-purity powder for each of the powders used, and the purity is more preferably 99.0% by mass or more, particularly 99.5% by mass or more. If magnesium titanate (MgTi ₂ O ₅ ) and iron titanate (Fe ₂ TiO ₅ ) can be dissolved in aluminum titanate (Al ₂ TiO ₅ ), in addition to these metal oxide powders Powders such as carbonates, hydroxides and nitrates may be used, and powders of these compounds may be used.

  Next, the obtained primary raw material is calcined in an air atmosphere at a temperature of 1400 ° C. or higher and 1500 ° C. or lower for 1 hour or more and 5 hours or less, so that the elements Ti, Al, Mg and Fe are dissolved in each other. A calcined powder composed of brookite-type crystals can be obtained.

By passing this calcined powder through a mesh sieve having a particle size number of 230 described in ASTM E 11-61, for example, a calcined powder having a particle size of 61 μm or less is obtained. The classified calcined powder has, for example, silicon oxide having an average particle size of 1 μm or more and 3 μm or less and an addition amount of 0.4 parts by mass or more and 1.2 parts by mass or less with respect to 100 parts by mass of the calcined powder. Powder of
Graphite whose addition amount is 1 to 13 parts by mass with respect to 100 parts by mass of the calcined powder,
After adding a pore-forming agent such as starch or polyethylene resin, a plasticizer, a thickener, a slipping agent and water are further added, and a kneaded product is prepared using a universal stirrer, rotary mill or V-type stirrer. . And this kneaded material is knead | mixed using a three roll mill, a kneader, etc., and the plasticized clay is obtained.

Next, this clay is formed using an extrusion molding machine. The extrusion molding machine is provided with a molding die, and the molding die has an inner diameter that determines the outer diameter of the molded body, for example, 155 mm to 300 mm, and the partition wall portion 2 and the cylindrical portion 5 of the honeycomb structures 11 to 15. has a slit for forming, this slit is, for example, the surface of the slit corresponding to the surface S ₂ of the surface S ₁ and the partition wall 2 of the tubular portion 5 forming the communication holes 18, the surface S ₁ has a continuously varying curved surface toward the surface S ₂ from, and corresponds to the shape of each of the partition wall 2 and the cylindrical portion 5 of the honeycomb structure 11 to 15.

  Then, the clay is put into an extrusion molding machine equipped with a molding die as described above, pressure is applied to produce a honeycomb-shaped molded body, and the obtained molded body is dried and cut into a predetermined length. .

  Next, the sealing material 9 which seals each of the inflow side and the outflow side of the plurality of flow holes of the cut molded body alternately is produced. Specifically, first, a checkered pattern is masked so that a portion sealed by the sealing material 9 is formed at the outflow side end surface (OF), and the outflow side end surface (OF) side of the molded body is mixed with the slurry mixture. Immerse in the smelt. In addition, the flow hole which is not masked is provided with a tip portion coated with water-repellent resin from the inflow side end face (IF), and a pin having a flat tip portion is inserted in advance. The slurry that has entered the flow holes on the outflow side is dried at room temperature. By doing in this way, the sealing material 9 of the outflow side of a molded object is formed. Then, the pin is removed, and the same operation as described above is performed on the inflow side of the molded body to form the sealing material 9.

  Next, the obtained molded body is fired by holding it in a firing furnace at a temperature of 1300 to 1500 ° C. for about 2 to 10 hours, thereby obtaining the honeycomb structures 11 to 15 of the present embodiment.

Next, when obtaining the honeycomb structures 11 to 15 made of a ceramic sintered body in which the main components of the partition wall portion 2, the sealing material 9 and the tubular portion 5 are cordierite, cordierite in the sintered body is obtained. composition SiO ₂ is 40 to 56 mass% of, _Al 2 _{O 3} is 30 to 46 wt%, such MgO is 12 to 16 wt%, kaolin, calcined kaolin, alumina, aluminum hydroxide, silica, talc Alternatively, a raw material to be converted into cordierite such as baked talc is prepared to obtain a mixed raw material. Thereafter, the steps until obtaining the honeycomb structures 11 to 15 are the same as the case where the main component is aluminum titanate except that the firing temperature is changed from 1300 to 1700 ° C. to 1350 to 1450 ° C.

  In order to regenerate the honeycomb structure, the honeycomb structures 11 to 15 thus manufactured can increase the strength on the outer side without reducing the amount of collected fine particles on the inner side. Even if the collected fine particles are frequently burned and removed, cracks hardly occur.

  Furthermore, in order to obtain the honeycomb structures 11 to 15 that carry the catalyst on the wall surfaces of the partition walls 2, the honeycomb structures 11 to 15 obtained by the above-described manufacturing method are used as catalysts, for example, ruthenium, rhodium, palladium. After immersing the honeycomb structures 11 to 15 obtained by the firing described above in a slurry composed of a soluble salt of a platinum group metal such as osmium, iridium and platinum, a binder such as polyvinyl alcohol and water, the temperature May be dried by holding at 100 ° C. to 150 ° C. for 1 hour to 48 hours. And after making it dry, the honeycomb structures 11-15 which carry | supported the catalyst on the wall surface of the partition part 2 can be obtained by heat-processing at the temperature of 600 to 700 degreeC for 2 hours or more and 4 hours or less.

Here, examples of the soluble salt include palladium nitrate (Pd (NO ₃ ) ₂ ), rhodium nitrate (Rh (NO) ₃ ) ₃ ), ruthenium chloride (RuCl ₃ ), chlorinated iridium acid (H ₂ IrCl _6. nH ₂ O), chloroplatinic acid (H ₂ PtCl ₆ .nH ₂ O), dinitrodiammine platinum (Pt (NO ₂ ) ₂ (NH ₃ ) ₂ ), etc., and these are soluble depending on the catalyst to be supported Choose from the salt. In order to prevent impurities from being mixed, the water is preferably ion-exchanged water.

  Further, ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-23, MCM zeolite, mordenite, faujasite, ferrierite are catalysts for storing and reducing nitrogen oxides (NOx) And at least one of zeolite beta is supported on at least one of the wall surface of the partition wall portion 2 and the pore surface of the partition wall portion 2, in addition to the platinum group metal, selected from alkali metals, alkaline earth metals, and rare earth metals What is necessary is just to add at least one of these to a slurry.

  And after accommodating in the case 7 in the state which coat | covered the outer periphery of the honeycomb structures 11-15 produced by the method mentioned above with the heat insulating material layer 6, the exhaust pipe 8a is made into the inflow port 7a of the case 7, and exhaust_gas | exhaustion By connecting the pipe 8b to the outlet 7b of the case 7, respectively, the gas processing apparatus 10 of this embodiment of the example shown in FIG. 7 can be obtained.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

First, a slurry prepared by mixing 30% by weight of aluminum oxide powder, 15% by weight of ferric oxide powder, 10% by weight of magnesium oxide powder and 10% by weight of the magnesium oxide powder and the balance of titanium oxide powder together with water is spray dried. To obtain granules having an average particle size of 175 μm. here,
The purity of each powder was 99.5% by mass.

  Next, the obtained granule is calcined in an air atmosphere at a temperature of 1450 ° C. for 3 hours, thereby calcining powder composed of pseudo-brookite crystals in which elements Ti, Al, Mg and Fe are dissolved in each other. Got.

This calcined powder was passed through a mesh sieve having a particle size number of 230 described in ASTM E 11-61 to obtain a calcined powder classified to a particle size of 61 μm or less. The classified calcined powder has, for example, a silicon oxide powder having an average particle diameter of 2 μm and an addition amount of 0.8 parts by mass with respect to 100 parts by mass of the calcined powder, and the addition amount is calcined. After adding 7 parts by mass or less of graphite to 100 parts by mass of the powder, a plasticizer, a thickener, a slipping agent, water and the like were further added, and a kneaded product was prepared using a universal stirrer. Then, a part of the kneaded material was left and kneaded using a kneader to obtain a plasticized clay.

Next, using the prepared clay, the curvature of the curved surface S in the honeycomb structure 11 shown in FIGS. 1 and 2 is 7.3 mm ⁻¹ , and the surface S ₃ of the cylindrical portion 5 is the surface of the partition wall portion 2. after obtaining the molded body G1 crossing the S ₄ and linearly by an extrusion method, dried and cut to length.

Similarly, the curvatures of the curved surface S and the curved surface S ′ are 7.3 mm ⁻¹ and 3.3 mm ⁻ , respectively.
^A molded body G2 to be ¹ was obtained by an extrusion molding method, then dried and cut into a predetermined length.

Further, similarly, a molded body G3 in which the curvatures of the curved surface S and the curved surface S ′ are respectively 7.3 mm ⁻¹ and 5 mm ⁻¹ was obtained by an extrusion molding method, and then dried and cut into a predetermined length.

As a comparative example, on the surface S ₂ surface S ₁ is the partition wall 2 of the tubular portion 5, also, the surface S ₃ of the tubular portion 5 intersects the surface S ₄ of the partition wall 2, each linear molding After the body G4 was obtained by an extrusion method, it was dried and cut into a predetermined length.

Next, after masking in a checkerboard pattern so that the sealing material 9 can be sealed at the outflow side end face (OF), the remaining kneaded material is slurried and the outflow side end face (OF) is immersed. . Then, the tip portion coated with water-repellent resin is immersed in the outflow side of the sintered body in the slurry, and the pin with the tip portion formed flat is sealed from the inflow side end surface (IF) After inserting into the flow hole forming the material 9 and adjusting the position of the tip of the pin so that the thickness of the sealing material 9 becomes 2.5 mm, the slurry that has entered the flow hole on the outflow side is cooled to room temperature. The sealing material 9 on the outflow side of the compacts G1 to G4 was formed respectively by drying at. Then, the pins were removed, and the same operation as described above was performed on the inflow side of the molded bodies G1 to G4 to form the inflow side sealing materials 9 respectively.

  Then, the compacts G1 to G4 were fired using an electric furnace at a firing temperature of 1380 ° C. and held for 3 hours to obtain a sample No. 1-4 were obtained.

Sample No. 1 to 4 each have an outer diameter of 144 mm, the length L in the axial direction A shown in FIG. 1 is 156 mm, and the number of flow holes per unit area in a cross section perpendicular to the axial direction A is 300 CPSI. It was. Moreover, the extrusion molding machine used by preparation of the molded objects G1-G4 each mounted | worn and used the shaping | molding die which has the slit for forming the cylindrical part 5 and the partition part 2 of the molded objects G1-G4.

And after each sample was accommodated in case 7 of the gas processing apparatus 10 shown in FIG. 7, the exhaust pipe 8a was connected to the diesel particulate generator (not shown), respectively. Then, from this device, dry air containing fine particles at a temperature of 25 ° C. is sprayed toward each sample at a flow rate of 2.27 Nm ³ / min per unit time, and the fine particles are applied to the honeycomb structure with a volume of 0.001 m ³ . 12g was collected.

  The honeycomb structure was regenerated by burning off the collected fine particles using an electric heater (not shown) arranged on the inflow side end face (IF) side of the honeycomb structure.

The regeneration condition is that the combustion temperature and the combustion time in the vicinity of the inflow side end face (IF) are 1250 ° C. and 10 minutes, respectively, and air is supplied to the honeycomb structure, and the flow rate of this air per unit time is 1.0 m ³ / min. did. After each sample is regenerated, the sample No. is again obtained by the same method as described above.
For 1 to 4 volumes of 0.001 m ³ , 12 g of fine particles were collected. Table 1 shows the number of cycles in which the cylindrical portion 5 was visually observed after this cycle was repeated and regenerated, and the cracks were observed for the first time.

  As shown in Table 1, sample no. Since No. 4 does not have a curved surface facing the cylindrical portion 5, the cylindrical portion 5 is easily distorted, and cracks were observed in the cylindrical portion 5 at a relatively early stage.

  On the other hand, sample No. 1 to 3 have a curved surface in which the flow hole 18 faces the cylindrical portion 5, the stress generated in the cylindrical portion 5 located on the extension line P is further relaxed, and the cylindrical shape located on the extension line P It was found that the difference in stress generated between the portion 5 and the tubular portion 5 located on the extension line Q is reduced, cracks are not easily generated in the tubular portion 5, and the strength of the honeycomb structure can be maintained high.

  Furthermore, sample no. 2 and 3, since the flow hole 19 has a curved surface facing the cylindrical portion 5, the stress generated in the cylindrical portion 5 located on the extension line Q is relieved, and cracks are less likely to occur in the cylindrical portion 5. I understood it.

  In view of the above, sample no. In Nos. 1 to 3, it was found that cracks hardly occur even when stress such as thermal stress is concentrated on the cylindrical portion 5, so that the strength is hardly lowered.

Next, using the clay used in Example 1, in the honeycomb structure 11 shown in FIGS. 1 and 2, the curvature of the curved surface S is 5 mm ⁻¹ , and the surface S ₃ of the tubular portion 5 is the partition wall portion. after obtaining the two surfaces S ₄ moldings G5 crossing the linear extrusion and dried and cut into a predetermined length.

Moreover, the curvature of the curved surface S in the honeycomb structure 12 shown in FIG. 3 is 5 mm ⁻¹ , and the cylindrical shape of the partition wall 2 constituting the flow holes 20 and 21 adjacent to the inner sides of the flow holes 18 and 19, respectively. A molded body G6 having a curvature (5mm ⁻¹ ) of the surface (curved surface) T on the part 5 side was obtained by an extrusion molding method, then dried and cut into a predetermined length.

  And after forming the sealing material 9 as shown in FIG. 1 in the molded products G5 and G6 using the same method as the method shown in Example 1, respectively, the molded products G5 and G6 are used using an electric furnace. Samples No. 1 and No. 2 were fired by holding at a firing temperature of 1380 ° C. for 3 hours to obtain honeycomb structures 11 and 12, respectively. 5 and 6 were obtained.

Sample No. 5 and 6, the outer diameter is 144 mm, the length L in the axial direction A shown in FIG. 1 is 156 mm, and the number per unit area of the flow holes 3 in the cross section perpendicular to the axial direction A is 300 CPSI. Moreover, the extrusion molding machine used for production of the molded bodies G5 and G6 was mounted with a molding die having a slit for forming the cylindrical portion 5 and the partition wall portion 2 of the molded bodies G5 and G6, respectively.

Then, after each sample is accommodated in the case 7 of the gas treatment device 10 shown in FIG. 7, the exhaust pipe 8a is connected to a diesel particulate generator (not shown), and then the same method as that shown in the first embodiment. The fine particles were collected by using the same method to regenerate the honeycomb structure. Example 1
The collection and regeneration shown in Fig. 1 was set as one cycle, and after completing this cycle, 15 cycles were cut perpendicular to the axial direction A using a wire saw, and the presence or absence of cracks in the cylindrical portion 5 was visually observed. Observed. Moreover, it was observed visually about whether the crack observed in the cylindrical part 5 propagated to the partition part 2 located in the 1st area | region M side.

  The results are shown in Table 2. “Good” in Table 2 indicates that cracks were observed after 15 cycles, and “Excellent” in Table 2 indicates that no cracks were observed after 15 cycles.

  As shown in Table 2, sample no. 6, since the surface T on the cylindrical portion 5 side of the partition wall portion 2 constituting the flow holes 20 and 21 is a curved surface, even if a crack occurs in the cylindrical portion 5, this crack is not generated on the inner partition wall portion 2. It became clear that it became difficult to propagate.

Next, using the clay used in Example 1, in the honeycomb structure 11 shown in FIGS. 1 and 2, the curvature of the curved surface S is 6 mm ⁻¹ , and the surface S ₁ of the tubular portion 5 is the partition wall portion. A molded body G7 linearly intersecting the surface S2 of ₂ was obtained by an extrusion molding method, then dried and cut into a predetermined length.

  Further, the honeycomb structure 13 shown in FIG. 4 was obtained by obtaining a molded body G8 in which the circulation holes 18 and the circulation holes 19 are circular shapes having respective opening diameters of 1.3 mm and 0.8 mm, respectively, by an extrusion molding method, and then dried. And cut to a predetermined length.

  And after forming the sealing material 9 as shown in FIG. 1 in the molded products G7 and G8 using the same method as the method shown in Example 1, respectively, the molded products G7 and G8 using an electric furnace, Sample Nos. 1 and 13 were fired by holding at a firing temperature of 1380 ° C. for 3 hours, respectively. 7 and 8 were obtained.

Sample No. 7 and 8 both have an outer diameter of 144 mm, the length L in the axial direction A shown in FIG. 1 is 156 mm, and the number per unit area of the flow holes 3 in the cross section perpendicular to the axial direction A is as follows. 300 CPSI. Moreover, the extrusion molding machine used for production of the molded bodies G7 and G8 was mounted with a molding die having a slit for forming the cylindrical portion 5 and the partition wall portion 2 of the molded bodies G7 and G8, respectively.

  Table 3 shows the number of cycles in which cracks were first observed in the cylindrical portion 5 of each sample in the same manner as in Example 1.

  As shown in Table 3, Sample No. In No. 8, since the through holes 18 and 19 are circular in the cross section, the stress generated in the tubular portion 5 can be more relaxed, so that cracks are hardly generated and the strength of the honeycomb structure can be maintained higher. .

Next, using the clay used in Example 1, the curvature of the curved surface S in the honeycomb structure 11 shown in FIGS. 1 and 2 is 6.5 mm ⁻¹ , and the surface S ₁ of the tubular portion 5 is a partition wall. after obtaining the molded body G9 intersecting the linearly in the surface S ₂ of part 2 by extrusion molding and dried and cut into a predetermined length.

  Further, in the honeycomb structure 14 shown in FIG. 5, each of the opening diameters of the circulation holes 18 and 20 is 1.3 mm, and each of the opening diameters of the circulation holes 19 and 21 is 0.8 mm. A shaped product G10 having a circular shape was obtained by extrusion molding, then dried and cut into a predetermined length.

  Further, in the honeycomb structure 15 shown in FIG. 6, the flow holes 18 and the flow holes 20 have circular shapes with respective opening diameters of 1.1 mm and 1.3 mm, respectively, and the opening diameters of the flow holes 19 and the flow holes 21 are 0.6 respectively. A molded body G11 having a circular shape of mm and 0.8 mm was obtained by an extrusion molding method, then dried and cut into a predetermined length.

  And after forming the sealing material 9 as shown in FIG. 1 in the molded products G9 to G11 using the same method as the method shown in Example 1, respectively, the molded products G9 to G11 using the electric furnace, The sample Nos. 1 and 14 and 15 were fired by holding at a firing temperature of 1380 ° C. for 3 hours, respectively. 9-11 were obtained.

Sample No. 9 to 11 each have an outer diameter of 144 mm, and the length L in the axial direction A shown in FIG. 1 is 156 mm. The number per unit area of the flow holes 3 in the cross section perpendicular to the axial direction A is 300 CPSI. Moreover, the extrusion molding machine used for production of the molded bodies G9 to G11 was used with a molding die having slits for forming the cylindrical portion 5 and the partition wall portion 2 of the molded bodies G9 to G11, respectively.

  Then, after each sample is accommodated in the case 7 of the gas treatment device 10 shown in FIG. 7, the exhaust pipe 8a is connected to a diesel particulate generator (not shown), and then the same method as that shown in the first embodiment. The fine particles were collected by using the same method to regenerate the honeycomb structure. Then, the collection and regeneration shown in Example 1 was set as one cycle, and after 25 cycles were completed, the wire saw was used to cut perpendicularly to the axial direction A, as shown in Example 2. The presence or absence of cracks in the cylindrical portion 5 was visually observed by the same method. Moreover, the partition part 2 was observed visually about whether the crack observed in the cylindrical part 5 was propagating to the partition part 2 located inward rather than the partition part 2 which divides the circulation holes 20 and 21.

Further, the same sample was prepared separately, and after 30 cycles, the presence or absence of cracks in the cylindrical portion 5 and the propagation of cracks to the partition wall portion 2 were observed using the same method as described above.

  The results are shown in Table 4. “Good” in Table 4 indicates that cracks were observed after completion of 25 cycles and 30 cycles, respectively, and “Excellent” in Table 4 indicates that no cracks were observed after completion of 25 cycles and 30 cycles, respectively. It shows that.

  As shown in Table 4, Sample No. 10 and 11, since the circulation holes 20 and 21 adjacent to the inner sides of the respective circulation holes 18 and 19 have a circular shape, a crack occurs in the cylindrical portion 5, and even if collection and regeneration are continued, It has been found that cracks are difficult to propagate to the inner partition 2.

  In particular, sample no. No. 11 has an opening area of the flow holes 18 and 19 smaller than that of the flow holes 20 and 21, so that a crack is generated in the cylindrical portion 5, and the crack is inward even if collection and regeneration are further continued. It turned out that it is difficult to propagate to the partition 2 on the side.

Next, using the clay used in Example 1, in the shape of the honeycomb structure 11 shown in FIGS. 1 and ₂ , continuously from the surface S ₁ of the tubular portion 5 to the surface S 2 of the partition wall portion 2. A molded body G12 having a curved surface S with a curvature of 5 mm ⁻¹ was obtained by an extrusion molding method, dried and cut into a predetermined length. In addition, this was repeated to produce another molded body G12.

  And after forming the sealing material 9 as shown in FIG. 1 in the molded body G12 using the same method as that shown in Example 1, respectively, the molded body G12 is fired at 1380 ° C. using an electric furnace. The sample was fired by holding for 3 hours, and the sample No. 12 and 13 were obtained.

And sample no. No. 12, Sample No. obtained by the above-described firing in a slurry composed of palladium nitrate (Pd (NO ₃ ) ₂ ), polyvinyl alcohol and water. 8 was dipped and dried by keeping the temperature at 130 ° C. for 24 hours, followed by heat treatment at 600 ° C. for 2 hours to obtain a honeycomb structure having a catalyst supported on the wall surface of the partition wall 2.

Sample No. 12 and 13 both have an outer diameter of 144 mm and a length L in the axial direction A shown in FIG. 1 of 156 mm. The number per unit area of the flow holes 3 in the cross section perpendicular to the axial direction A is 300 CPSI.

Then, after each sample is accommodated in the case 7 of the gas treatment device 10 shown in FIG. 7, the exhaust pipe 8a is connected to a diesel particulate generator (not shown), and then the particulates are contained from this device at a temperature of 25 ° C. The dry air was sprayed toward each sample with a flow rate per unit time of 2.27 Nm ³ / min, and 12 g of fine particles were collected for a volume of 0.001 m ³ of the honeycomb structure.

Then, using an electric heater (not shown) arranged on the inflow side end face (IF) side of the honeycomb structure, the temperature in the vicinity of the inflow side end face (IF) is set to 300 ° C.
Burned off over a period of minutes. During this period, air was supplied to the honeycomb structure, and the flow rate of this air per unit time was set to 1.0 m ³ / min.

  When the state of the remaining unburned particles was visually observed from the inflow side end face (IF) side of the honeycomb structure, Sample No. No. 12 has a catalyst supported on the wall surface of the partition wall 2, and therefore sample No. 12 which does not support the catalyst on the wall surface of the partition wall 2. It was found that there was less unburned fine particles than 13. That is, sample no. Sample No. 12 Since the combustion efficiency of fine particles is better than that of 13, fine particles can be burned and removed in a shorter time or at a lower temperature, and it can be said that melting and cracking are less likely to occur in the partition wall 2.

  As described above, when the gas treatment device 10 of the present embodiment includes the honeycomb structure of the present embodiment shown in Examples 1 to 5, the cylindrical portion 5 is hardly cracked, and this crack is not generated. Even if it occurs in the cylindrical part 5, it is difficult to propagate to the partition part 2, so it can be said that it can be used efficiently over a long period of time.

11, 12, 13, 14, 15: Honeycomb structure 2: Partition part 3: Inflow path 4: Outflow path 5: Cylindrical part 6: Thermal insulation layer 7: Case 8: Exhaust pipe 9: Sealing material
10: Gas processing equipment
16, 17, 18, 19, 20, 21: Distribution hole

Claims (7)

A tubular part;
A partition wall portion arranged in a lattice shape so as to provide a plurality of flow holes inside the tubular portion, and
The plurality of flow holes have a first flow hole and a second flow hole having different opening diameters arranged in a row from the inside to the outside inside the cylindrical part,
A honeycomb structure characterized in that a third flow hole having a curved surface facing the cylindrical portion is provided on an extension line in the arrangement direction of the first flow holes having a large opening diameter.   A fourth circulation hole having a curved surface facing the cylindrical portion is provided on an extension line in the arrangement direction of the second circulation holes having a small opening diameter, and the length of the curved surface in the third circulation hole is provided. The honeycomb structure according to claim 1, wherein the length of the curved surface is longer than the length of the curved surface in the fourth flow hole.   The surface of the cylindrical part side of the fifth circulation hole and the sixth circulation hole existing adjacent to the inside of each of the third circulation hole and the fourth circulation hole is a curved surface. The honeycomb structure according to claim 2, wherein:   The honeycomb structure according to any one of claims 1 to 3, wherein the third flow hole has a circular shape.   The honeycomb structure according to claim 3, wherein each of the fifth flow hole and the sixth flow hole has a circular shape.   The opening area of the third circulation hole is smaller than the opening area of the fifth circulation hole, and the opening area of the fourth circulation hole is smaller than the opening area of the sixth circulation hole. The honeycomb structure according to claim 5. A gas treatment apparatus comprising the honeycomb structure according to any one of claims 1 to 6.

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