JP5762138B2 - Honeycomb structure and gas processing apparatus using the same - Google Patents

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 using 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 provided in an exhaust gas processing apparatus, and is formed by a cylindrical portion and a partition wall portion having air permeability arranged in a lattice shape inside the cylindrical portion, and an exhaust gas inlet and an outlet are provided. A honeycomb structure having a plurality of flow holes sealed alternately with a sealing material 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 in which the fine particles are burned and removed by heating to 600 ° C. or more, or an oxidation catalyst is arranged on the exhaust gas inflow side of the filter However, there is a method of burning and removing fine particles using heat generated by an oxidation reaction caused by supplying fuel such as light oil to this oxidation catalyst, and it is efficiently contained in exhaust gas by repeating regeneration. Fine particles were collected.

  However, when the filter is regenerated by these methods, the larger the amount of collected particulate matter, the more time it takes to burn off the particulates. During this time, the temperature of the filter rises, and the thermal stress due to the temperature rise. In some cases, the filter may crack or melt.

  In order to prevent such cracks and melting damage, for example, in Patent Document 1, a large number of through holes are arranged in parallel in the longitudinal direction with a partition wall therebetween, and one of these through holes is sealed. A honeycomb structure comprising one or more combinations of columnar porous ceramic members, wherein the honeycomb structure has an opening area on one end face different from an opening area on the other end face, A honeycomb structure in which a ceramic member is formed of a silicon-ceramic composite material made of ceramics and silicon has been proposed, and the through hole has a large volume through hole having a relatively large cross-sectional area perpendicular to the longitudinal direction, It consists of two types of through-holes, a small-volume through-hole with a relatively small cross-sectional area, and the large-volume through-hole is sealed with a sealing material at the end on the exhaust gas outlet side of the honeycomb filter. Volume penetration Is sealed with a plug at the end of the exhaust gas inlet side of the honeycomb filter, the partition wall separating the through holes to each other is allowed to function as a filter.

International Publication No. 2004/113252 Pamphlet

  However, the honeycomb filter proposed in Patent Document 1 does not sufficiently consider the improvement of the collection efficiency of the fine particles, and thus has a problem that the collection efficiency is low.

  The present invention has been devised to solve the above problems, and an object of the present invention is to provide a honeycomb structure with improved particulate collection efficiency and a gas processing apparatus using the honeycomb structure.

The honeycomb structure of the present invention is formed by a tubular portion and a partition wall portion having air permeability arranged in a lattice shape inside the tubular portion, and is partitioned by the partition wall portion to provide a fluid inlet and a flow passage. outlet Ri honeycomb structure der comprising a plurality of flow holes sealed alternately by a sealing material, in the cross section perpendicular to the direction of flow of the fluid in the flow hole, wherein the central portion flow hole is partitioned by the partition wall portion having a straight portion, the tubular portion side, together with our Keru the partition wall portion is curved in at least a portion of the flow hole in contact with the cylindrical portion, has the through-holes partitioned by a curved the partition wall portion is provided continuously region, the center and the 60 ° der Rukoto less central angle 30 ° or more formed by the cross section and the area It is a feature.

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

According to the honeycomb structure of the present invention, it is formed of a cylindrical portion and a partition wall portion having air permeability disposed inside the cylindrical portion in a lattice shape, and is partitioned by the partition wall portion to be a fluid inflow port. and the outflow port Ri honeycomb structure der comprising a plurality of flow holes sealed alternately by a sealing material, in the cross section perpendicular to the direction of flow of the fluid in the flow holes, the central portion the flow holes in the is partitioned by the partition wall portion having a straight portion, the tubular portion, the partition wall Contact Keru at least a portion of the flow hole in contact with the cylindrical portion is curved together have the through-holes partitioned by a curved the partition wall portion is provided continuously regions, the central angle formed between the center of the cross section and the area is Ru der 30 ° to 60 ° Therefore, the surface area of this partition is increased. Runode, collection efficiency of the particulate is high such Rutotomoni, mechanical strength becomes high.

  Further, according to the gas treatment device of the present invention, when the honeycomb structure of the present invention is provided, the particulate collection efficiency tends to be high.

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. 1B is a partially enlarged view showing an example of the cylindrical portion side and the central portion side in the cross section taken along the line CC ′ of FIG. 1B of the honeycomb structure of the example shown in FIG. It is. It is a mimetic diagram showing the state where the partition part which constitutes the honeycomb structure of this embodiment is curving. (A), (b) is the elements on larger scale which show the example of the cylindrical part side and the center part side in the cross section of another honeycomb structure, respectively. Further, (a) and (b) in a cross section of another honeycomb structure are partially enlarged views showing examples of the cylindrical portion side and the central portion side, respectively. It is a schematic sectional drawing which shows typically an example of the gas processing apparatus of this embodiment.

  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).

  FIG. 2 is a cross-sectional view taken along the line CC ′ of FIG. 1B of the honeycomb structure of the example shown in FIG. It is the elements on larger scale which show an example.

  The honeycomb structure 1 of the example shown in FIG. 1 and FIG. 2 is formed by a cylindrical portion 5 and a partition wall portion 2 having air permeability arranged inside the cylindrical portion 5 in a lattice shape. The honeycomb structure 1 includes a plurality of flow holes 3 alternately sealed with a sealing material 4 on the fluid inlet (IF) side and outlet (OF) side.

Then, at least a part of the flow holes in contact with the cylindrical portion 5 in a cross section (hereinafter sometimes simply referred to as a cross section) perpendicular to the direction in which the fluid flows (hereinafter may be simply referred to as the axial direction A). 2 is curved. Except for the flow holes 3c and 3d partitioned by the curved partition wall 2, the shapes of the other flow holes 3a and 3b are, for example, the honeycomb structure shown in FIG. Like the central part side in the cross section of the body 1, it has an octagonal shape and a quadrangular shape, respectively.

Such a honeycomb structure 1 has, for example, a cylindrical shape with an outer diameter of 140 to 270 mm and a length L in the axial direction A of 100 to 250 mm, and a flow hole in a cross section perpendicular to the axial direction A. 3 is 5 to 124 (32 to 800 CPSI) per 100 mm ² . Moreover, the partition part 2 is 0.05 mm or more and 0.25 mm or less in thickness, and the sealing material 4 is 1 mm or more and 5 mm or less in thickness. CPSI stands for Cells Per Square Inches.

  In such a honeycomb structure 1, an internal combustion engine (not shown) such as a diesel engine or a gasoline engine is disposed on the inflow side, and exhaust gas generated by operating the internal combustion engine is as shown in FIG. Are introduced from the flow holes 3a in which the sealing material 4a on the inlet (IF) side of the honeycomb structure 1 is not formed, and the outflow is blocked by the sealing material 4b formed on the outlet (OF) side. The exhaust gas from which the outflow is blocked passes through the gas-permeable partition wall 2 and is introduced into the adjacent circulation hole 3b. 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”) are collected. The exhaust gas in which the fine particles are collected is discharged to the outside through the flow hole 3b in which the sealing material 4b is not formed in a purified state.

  In such a honeycomb structure 1, it is important that the partition wall portion 2 is curved in at least a part of the flow holes 3 in contact with the tubular portion 5.

  When the partition wall portion 2 is curved in at least a part of the flow holes 3 in contact with the tubular portion 2, the surface area of the partition wall portion 2 increases, so that when the exhaust gas passes through the partition wall portion 2, the partition wall portion 2. Since the amount of collected fine particles in the exhaust gas increases on the wall surface of the wall and the pore surface of the partition wall portion 2, the collection efficiency of the fine particles in the vicinity of the cylindrical portion 5 is likely to increase.

  Moreover, it is preferable that the honeycomb structure 1 of the present embodiment has a region in which the flow holes 3 partitioned by the curved partition wall portion 2 are continuously provided.

  FIG. 3 is a schematic view showing a state in which the partition walls constituting the honeycomb structure of the present embodiment are curved.

Here, the region in which the flow holes 3 partitioned by the curved partition wall 2 are continuously provided is, for example, any flow hole in which the outflow side is sealed with the sealing material 4 as shown in FIG. Among the partition walls 2 partitioning 3, the maximum displacement W from the virtual line connecting the adjacent intersections 2 b ₁ and 2 c ₁ of the partition wall 2 b and the partition wall 2 c intersecting the partition wall 2 a is the length L of the virtual line The partition portion having the flow holes 3c and 3d partitioned by the partition wall portion 2a that is 25% or more of the partition wall portion, and the partition wall portion having a ratio W / L of 25% or more is at least one of the partition wall portions partitioning the flow hole 3. I need only one.

  Note that the maximum value W of the displacement from the virtual straight line and the length L of the virtual straight line may be measured using an optical microscope at a magnification of, for example, 50 times to 100 times.

In particular, in the honeycomb structure 1 of the present embodiment, it is preferable that the central angle formed by the region and the center of the cross section is 30 ° or more and 60 ° or less. When the central angle formed by this region and the center of the cross section is within this range, the central angle is 30 ° or more, so that the surface area of the partition wall portion 2 in the vicinity of the cylindrical portion 5 is increased, and the particulate collection efficiency is high. When the central angle is 60 ° or less, the area of the portion where the partition walls 2 are not curved can be secured widely, so that the mechanical strength of the honeycomb structure 1 is increased. It tends to be a honeycomb structure having sufficient strength.

  In addition, the honeycomb structure 1 of the present embodiment preferably includes a plurality of regions, and the portions of the cylindrical portion 5 corresponding to the center in each region are located at equal intervals in the cross section. Since the regions are located at equal intervals in this way, in the honeycomb structure 1, stress concentration on a specific part can be prevented and the occurrence of cracks can be suppressed.

  And the part of the cylindrical part 5 corresponding to the center in the region is located at intervals of 30 ° ± 2 °, 45 ° ± 2 °, 60 ° ± 3 ° or 90 ° ± 3 ° with the center of the cross section as the rotation center. By doing so, even if combustion removal of the collected fine particles is repeated frequently, the stress is dispersed and the mechanical strength is hardly lowered, which is preferable. In addition, in this embodiment, equal intervals shall mean that the site | part of the cylindrical part 5 is located in the range of the said angle.

  4A and 4B are partially enlarged views showing examples of the cylindrical portion side and the central portion side in the cross section of another honeycomb structure.

The honeycomb structure 20 of the example shown in FIG. 4 is partitioned by the curved partition wall portion 2 adjacent to the central direction of the cylindrical portion 5, and is cylindrical in the flow holes 3 c and 3 d adjacent to the central direction of the cylindrical portion 5. when the partition wall of the partition wall portion a extending toward the center from the outer peripheral parts 5, the partition wall portion to be connected to the partition wall a and the partition wall portion B, the adjacent communication holes 3c, the partition wall a partitioning the 3d, the cylindrical portion when viewed from the side toward the center, and the position of the partition wall portion a is connected to the partition wall B, and the honeycomb structure 20 that has misaligned as the starting point of the partition wall portion a extending toward the center from the partition wall B. When the partition wall portion A is positioned with respect to the partition wall portion B as in the honeycomb structure 20 in the example shown in FIG. 4A, the collected particulates are frequently burned and removed, and the partition wall Even if a crack occurs in the portion A, the crack propagates to the partition wall portion B and hardly progresses, and therefore it can be used for a long period of time.

  FIG. 5 is a partially enlarged view showing an example of the cylindrical portion side and the central portion side, respectively, in a cross section of still another honeycomb structure.

The honeycomb structure 30 of the example shown in FIG. 5 has an opening shape of the flow hole 3a sealed by the outflow side sealing material 4b and the opening shape of the flow hole 3b sealed by the inflow side sealing material 4a , respectively. It has a square shape and a quadrangular shape, and the corners of the opening are arcuate. Further, the honeycomb structure 30 has a larger opening area in the flow hole 3a on the outlet side than in the flow hole 3b on the inlet side.

As shown in FIG. 5, communication holes 3a and flow holes 3b are octagonal shape of the opening, respectively, a square shape, if the corner portion of the opening is arcuate in around corners Since the stress is less likely to concentrate on the surface, cracks are less likely to occur from the corners even when heating and cooling are repeated, and the flow hole 3a on the outlet side is more open than the flow hole 3b on the inlet side. Since it is large, the respective surface areas of the partition wall 2 and the sealing material 4b capable of adsorbing the fine particles are increased, and the fine particles can be efficiently collected.

In addition, in the honeycomb structures 1, 20, and 30 of the examples shown in FIGS. 1, 2, 4, and 5, the outflow side is sealed with the sealing material 4b and distributed by the partition wall 2 that is not curved. The diameter of the hole 3a is preferably 1.55 times or more and 1.95 times or less than the diameter of the flow hole 3b partitioned by the non-curved partition part 2 whose inflow side is sealed with the sealing material 4a. is there. Thus, by setting the ratio of the diameters to 1.55 times or more, the respective surface areas of the partition wall portion 2 and the sealing material 4b capable of adsorbing the fine particles are increased, so that the amount of collected fine particles can be increased. In addition, by making the ratio of the diameters 1.95 times or less, the partition wall portion 2 is not extremely thinned, so that the mechanical strength is not easily lost. Here, the diameters of the flow holes 3a and 3b are the inlet (IF).
The diameter of the inscribed circle in contact with the partition wall 2 on the side end face can be measured using an optical microscope.

In addition, the components constituting the partition wall portion 2, the sealing material 4 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 4 and the cylindrical part 5 refers to a component that occupies an amount of more than 50% by mass with respect to 100% by mass of the total component constituting each member, This component is identified by X-ray diffraction, and the content of the component can be determined by ICP emission spectroscopy or fluorescent X-ray analysis.

Further, the partition wall 2, the sealing member 4 and both the tubular portion 5 when mainly 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, when both the partition wall portion 2, the sealing material 4 and the cylindrical portion 5 are mainly composed of aluminum titanate (Al ₂ TiO ₅ ), each of the partition wall portion 2, the sealing material 4 and the cylindrical portion 5 is used. 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 within this range, the corrosion resistance of the partition wall portion 2, the sealing material 4 and the cylindrical portion 5 with respect to the sulfate is hardly impaired.

  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 structures 1, 20, and 30 of the embodiment of the example shown in FIGS. 1, 2, 4, and 5, the partition wall portion 2 has a porosity of 35 volume% to 60 volume%, It is preferable that the porous ceramic sintered body has an average pore diameter of 5 μm or more and 26 μm or less. 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. 6 is a schematic cross-sectional view schematically showing an example of the gas processing apparatus of the present embodiment.

The gas processing apparatus 10 of the present embodiment of the example shown in FIG. 6 includes the honeycomb structures 1, 20, and 30 of the present embodiment in which a catalyst (not shown) is supported on the wall surface of the partition wall portion 2, and the flow holes 3a and 3c. The other end of the flow hole 3a, 3c and the other flow hole 3b, 3d via the partition wall 2 is the other non-sealed outlet, and the exhaust gas (EG) is exhausted. This is a gas processing device that collects fine particles in the exhaust gas (EG) by the partition wall portion 2 by passing them through. The honeycomb structure 1 is accommodated in the case 7 with the 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, SUS303, S
Made of stainless steel such as US304 and SUS316, the central portion is formed in a cylindrical shape and both end portions are formed in a truncated cone shape, and the inflow port 8a and exhaust gas (EG) of the case 7 to which exhaust gas (EG) is supplied. The outlet 8b is discharged. An exhaust pipe 9 is connected to the inlet 8 a of the case 7, and exhaust gas (EG) is configured to flow into the case 7 from the exhaust pipe 9.

An internal combustion engine (not shown) such as a diesel engine or a gasoline engine is connected to the inflow side of such a gas processing device 10 through an exhaust pipe 9, and the internal combustion engine is operated to generate exhaust gas (EG). When supplied from the exhaust pipe 9 to the case 7, exhaust gas (EG) is introduced into the flow holes 3a and 3c where the sealing material 4a on the inflow side of the honeycomb structures 1, 20 and 30 is not formed. However, the outflow is blocked by the sealing material 4b formed on the outflow side. Exhaust gas (EG) whose outflow is blocked passes through the gas-permeable partition wall portion 2 and is introduced into the adjacent circulation holes 3b and 3d. 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 have been collected is in a purified state through an exhaust pipe (not shown) connected to the outlet 8b from the circulation holes 3b and 3d where the sealing material 4b is not formed. Discharged outside.

  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 1, 20 and 30 of the present embodiment, as described above, when the catalyst is supported on the wall surface of the partition wall portion 2, when the honeycomb structure is regenerated, the particulates are easily burned and removed at a low temperature. Therefore, the partition wall 2 is less likely to be melted or cracked. 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 structures 1, 20, and 30 that are examples of the present embodiment, cracks are less likely to occur in the honeycomb structures 1, 20, and 30. Therefore, it can be used efficiently over a long period of time, and a carrier carrying an active metal or a carrier carrying a NOx occlusion material can be made unnecessary, thereby realizing space saving. You can also.

  In addition, the application is, for example, an internal combustion engine which is a power source of automobiles, forklifts, generators, ships, hydraulic excavators, bulldozers, wheel loaders, rough terrain cranes, tractors, combiners, tillers, railway vehicles, construction vehicles, etc. , It can be used in filters that collect fine particles mainly composed of carbon contained in exhaust gas generated from incinerators, boilers, etc., filters that decompose and remove harmful dioxins, and the like.

  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 1, 20 and 30 will be described.

In the case of obtaining the honeycomb structure 1 made of a ceramic sintered body in which the bulkhead portion 2, the sealing material 4 and the cylindrical portion 5 are all made of aluminum titanate, first, 27 to 33 powders of aluminum oxide are used. Mass%, ferric oxide powder 13-17% by mass, magnesium oxide powder 7-13% by mass, and the balance titanium oxide powder. And mixed together to obtain the 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 diameter of 1 μm or more and 3 μm or less and an addition amount of 0.4 parts by mass or more and 4.6 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. Moreover, the slurry for providing the sealing material 4 by adding water further to a part of kneaded material mentioned above is produced.

  Next, this clay is formed using an extrusion molding machine. The extrusion molding machine is equipped with a molding die, and the molding die has an inner diameter that determines the outer diameter of the molded body, for example, from 155 mm to 300 mm, and forms the partition wall portion 2 and the tubular portion 5 of the honeycomb structure 1. It has a slit to do. Then, in order to have a plurality of regions where at least a part of the partition wall portion 2 in the vicinity of the tubular portion 5 is curved along the tubular portion 5 at predetermined intervals, the curved portion is curved on the outer peripheral side of the mold. A plurality of regions having the slits may be provided at predetermined intervals along the outer periphery of the mold.

  In addition, for example, in order for the curved region of the partition wall 2 to have a central angle between the curved region of the partition wall 2 and the center of the cross section being 30 ° or more and 60 ° or less, a curved slit A mold having a central angle formed by the region having the cross section and the center of the cross section of 30 ° or more and 60 ° or less, and more preferably 32 ° or more and 58 ° or less may be used.

  Further, for example, in order that the curved regions of the partition walls 2 are positioned at equal intervals in the cross section, the region having the curved slits may be provided in the mold so as to be positioned at equal intervals in the cross section. .

  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 4 which seals each of the end surface on the inflow port (IF) side and the end surface on the outflow port (OF) side of the plurality of flow holes 3 of the cut molded body is produced. Specifically, first, the end face on the outlet (OF) side is masked in a checkered pattern so that the sealing material 4b is sealed at the end face on the outlet (OF) side, and the end face on the outlet (OF) side of the molded body is slurried. Immerse in the kneaded material. In addition, the flow holes 3a, 3c that are not masked are provided with a tip portion that is coated with a water-repellent resin from the end surface on the inlet (IF) side, and a pin having a flat tip portion is formed. The slurry that has been inserted in advance and entered the flow holes 3a and 3c at the end face on the outlet (OF) side is dried at room temperature. By doing in this way, the sealing material 4b of the end surface by the side of the outflow port (OF) of a molded object is formed. And the said pin is extracted and the same operation | work as the above-mentioned operation | work is performed also on the end surface by the side of the inflow port (IF) of a molded object, and the sealing material 4a is formed.

  Next, the obtained molded body is fired by holding it in a firing furnace at a temperature of 1300 ° C. to 1500 ° C. for 2 to 10 hours to obtain honeycomb structures 1, 20 and 30 of the present embodiment. Can do.

Next, when obtaining honeycomb structures 1, 20 and 30 made of a ceramic sintered body in which the main components of the partition wall portion 2, the sealing material 4 and the cylindrical portion 5 are cordierite, The cordierite composition is kaolin, calcined kaolin, alumina, aluminum hydroxide, silica so that the composition of SiO ₂ is 40 to 56 mass%, Al ₂ O ₃ is 30 to 46 mass%, and MgO is 12 to 16 mass%. A raw material to be converted into cordierite such as talc or baked talc is prepared to obtain a mixed raw material. Thereafter, the steps until obtaining the honeycomb structure 1 are the same as in the case where the component is aluminum titanate.

  Since the honeycomb structure 1 manufactured in this way can increase the strength on the outer peripheral side without reducing the amount of collected fine particles on the inner peripheral side, the outer peripheral polishing is performed to form the tubular portion 5. Even if the collected fine particles are repeatedly burned and removed in order to regenerate or regenerate the honeycomb structure, cracks are less likely to occur.

  Furthermore, in order to obtain a honeycomb structure carrying the catalyst on the wall surface of the partition wall portion 2, the honeycomb structures 1, 20 and 30 obtained by the above-described manufacturing method are used as catalysts, for example, ruthenium, rhodium, palladium, After immersing the honeycomb structures 1, 20 and 30 obtained by the above-described firing 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, What is necessary is just to dry by hold | maintaining temperature at 100 to 150 degreeC for 1 to 48 hours.

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) In addition to platinum group metals, at least one of zeolite beta and zeolite beta is supported on at least one of the wall surface of partition wall 2 and the surface of pores of partition wall 2 is 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 1,20 and 30 manufactured by the method mentioned above with the heat insulating material layer 6, the exhaust pipe 9 is made into the inflow port 8a of the case 7, By connecting an exhaust pipe (not shown) to the outlet 8b of the case 7, the gas processing apparatus 10 of this embodiment of the example shown in FIG. 6 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 mass of aluminum oxide powder, 14% by mass of ferric oxide powder, 10% by mass of magnesium oxide powder and 46% by mass of titanium oxide powder and mixing with water. Drying was performed by spray drying 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. After adding 100 parts by mass of the classified calcined powder, the addition amount of 2.5 parts by mass of silicon oxide powder having an average particle diameter of 2 μm and the addition amount of 7 parts by mass of polyethylene resin are added. Further, a plasticizer, a thickener, a slip agent, water and methyl cellulose as a molding aid were added to obtain a mixture, and this mixture was put into a universal stirrer to prepare a kneaded product. This kneaded product was further kneaded using a kneader to obtain a plasticized clay. Moreover, the slurry for providing the sealing material 4 by adding water further to a part of mixture mentioned above was produced.

  Next, clay is put into a horizontal extrusion molding machine equipped with a mold for obtaining a molded body to be the honeycomb structure 1 shown in FIGS. 2 (a) and 2 (b), and pressure is applied to form a honeycomb. And then dried and then cut into a predetermined length.

  Next, the sealing material 4 which seals each of the end surface on the inflow port (IF) side and the end surface on the outflow port (OF) side of the plurality of flow holes 3 of the cut molded body was produced. Specifically, first, the end surface on the outlet (OF) side was masked in a checkered pattern so that a portion sealed by the sealing material 4b was formed, and the end surface was immersed in a slurry for providing the sealing material 4b. In addition, the flow holes 3a, 3c that are not masked are provided with a tip portion that is coated with a water-repellent resin from the end surface on the inlet (IF) side, and a pin having a flat tip portion is formed. The slurry inserted in advance and infiltrated into the end face on the outlet (OF) side of the flow holes 3a, 3c is dried at room temperature to form the sealing material 4b on the end face on the outlet (OF) side of the molded body. did. And the said pin was extracted and the same operation | work as the above-mentioned operation | work was performed also on the end surface by the side of the inflow port (IF) of a molded object, and the sealing material 4a was formed.

  Further, as a comparative example, in the vicinity of the tubular portion, the clay is put into a horizontal extrusion molding machine equipped with a mold for obtaining a molded body in which the partition wall portion is not curved, and pressure is applied to form a honeycomb shape. After forming and drying, it was cut into a predetermined length. And the sealing material 4 which seals each of the inflow side and the outflow side of the some through-hole 3 of the molded object cut | disconnected by the method same as the method mentioned above alternately was formed.

  In the case where there are a plurality of regions where the partition wall 2 is curved, Table 1 shows the number of regions and the central angle, and the arrangement thereof is equally spaced.

Next, the honeycomb formed body is placed in an electric furnace so that the inlet is on the lower side, and the firing temperature is set to 1380 ° C. and held for 3 hours to fire the outer diameter and height. , The thickness of the partition wall portion 2 and the number of the flow holes 3 in the cross section perpendicular to the axial direction A are 144 mm, 152 mm, 0.2 mm, and 300 CPI, respectively. 1-15 were obtained. At this time, the diameter of the flow hole 3a sealed at the end face on the outlet (OF) side is 1.4 with respect to the diameter of the flow hole 3b sealed at the end face on the inflow side (IF) side. The porosity and average pore diameter of the partition wall part 2 were 44% by volume and 14 μm, respectively.

  A sample for measuring the isostatic fracture strength and a sample for measuring the amount of collected fine particles were prepared for each sample.

And in order to evaluate the collection efficiency of each sample, each sample is accommodated in the case 7 of the gas treatment device 10 shown in FIG. 6, and the exhaust pipe 9 is made of a carbon generator (Nippon Kanomax Co., Ltd., model S4102). After connecting to the notch (not shown), the pressure loss (PL ₀ ) of the end face on the outlet (OF) side relative to the end face on the inlet (IF) side was measured by a manometer. Then, 12 g of fine particles were collected for a volume of 0.001 m ³ of the honeycomb structure by directly injecting dry air containing fine particles from a carbon generator at a temperature of 25 ° C. at a flow rate of 2.27 Nm ³ / min. The pressure loss (PL ₁ ) of the end face on the outlet (OF) side with respect to the end face on the inlet (IF) side at that time was measured with a manometer, and these measured values are shown in Table 1. Further, ΔPL (= PL ₁ −PL ₀ ) indicating an increase in pressure loss was calculated, and the value is shown in Table 1. It can be said that the smaller the value of ΔPL, the higher the collection efficiency.

  As shown in Table 1, sample no. 2 to 15 are sample Nos. Since the surface area of the partition wall portion 2 is larger than that of 1, the increase in pressure loss can be suppressed and the collection efficiency of the fine particles is increased. From the above, the partition wall 2 is curved in at least a part of the flow holes 3 in contact with the cylindrical portion 5, so that the collection efficiency is increased even if the collected particulates are repeatedly removed by combustion. I can see that

  Next, by using the clay used in Example 1, the shape of the central portion of the honeycomb structure 1 is FIG. 4B, and the portion where the partition wall portion 2 is curved is the adjacent flow hole 3. 4A is a shape in which the partition wall portion A in FIG. 16, the partition wall 2 of the adjacent flow hole 3 is not displaced and FIG. 17 and Sample No. 1 of Example 1 in which the flow hole 3 having the partition wall 2 curved around the entire circumference is formed. Sample No. 15 The kneaded material was put into a horizontal extrusion molding machine equipped with molds for obtaining molded bodies to be 18, and formed into a honeycomb shape by applying pressure, dried, and then cut to a predetermined length.

  Sample No. 16 and 17 have a region where the central angle formed by the region and the center of the cross section is 45 ° in the cross section perpendicular to the fluid flow direction in the flow hole 3. There were also 4 bodies.

Next, the honeycomb formed body is placed in an electric furnace so that the inlet is on the lower side and fired, so that the outer diameter, the height, the thickness of the partition wall 2 and the axis direction A are perpendicular to each other. A honeycomb structure in which the number of flow holes 3 in a simple cross section was 144 mm, 152 mm, 0.2 mm, and 300 CPI, respectively, was obtained. At this time, the diameter of the flow hole 3a sealed on the outlet side is 1.4 times the diameter of the flow hole 3b sealed on the inlet side, and the porosity and average pore diameter of the partition wall portion 2 are set. Each sample was 44% by volume and 14 μm, respectively.

  And after forming sealing material 4a, 4b using the same method as the method shown in Example 1, a molded object is baked by hold | maintaining for 3 hours at the calcination temperature of 1380 degreeC using an electric furnace. Sample No. which is a honeycomb structure. 16, 17 and 18 were obtained.

Sample No. The outer diameter and height of 16, 17 and 18, the thickness of the partition wall 2 and the number of flow holes 3 in the cross section perpendicular to the axial direction A are 144 mm, 152 mm, 0.2 mm and 300 CPI, respectively.
It is.

And after each sample was accommodated in case 7 of the gas processing apparatus 10 shown in FIG. 6, the exhaust pipe 9 was each connected to the diesel particulate generator (not shown). 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 and removing the collected fine particles using an electric heater (not shown) arranged on the end face side of the inlet (IF) of the honeycomb structure.

  The reproduction conditions were the same as the reproduction conditions shown in Example 1. Then, the collection and regeneration were set as one cycle, and after 15 cycles were completed, the wire saw was used to cut perpendicularly to the flow direction of the fluid in the flow hole 3 to be generated in the partition wall A. The presence or absence of cracks was visually observed. In addition, the cracks observed in the partition wall portion A are the sample No. The number was confirmed by observing whether it propagated to the partition walls B of 16, 17, and 18.

  The results are shown in Table 2.

  As shown in Table 2, sample no. In No. 17, cracks did not propagate to the partition wall B. Therefore, since the partition wall A is positioned with respect to the partition wall B, even if a crack is generated in the partition wall A, the crack is difficult to propagate to the partition wall B, so that it should be used for a long period of time. Can be said.

  As described above, when the gas treatment device 10 of the present embodiment is provided with the honeycomb structure of the present embodiment shown in Examples 1 and 2, the mechanical strength is not easily lowered, and in the vicinity of the tubular portion. Since the collection efficiency of fine particles is high, it can be said that durability can be increased.

  Further, the gas processing apparatus 10 of the present embodiment does not require a carrier carrying an active metal or a carrier carrying a NOx occlusion material when a honeycomb structure carrying a catalyst is supported on the wall surface of the partition wall 2. Therefore, it can be said that space saving can be realized.

DESCRIPTION OF SYMBOLS 1,20,30: Honeycomb structure 2: Partition part 3: Flow hole 4: Sealing material 5: Cylindrical part 6: Thermal insulation layer 7: Case 8a: Inlet 8b: Outlet 9: Exhaust pipe
10: Gas processing equipment

Claims (4)

It is formed by a cylindrical portion and a gas-permeable partition wall arranged inside the cylindrical portion in a lattice shape, and the fluid inlet and outlet are alternately separated by a sealing material. Ri honeycomb structure der comprising a sealed plurality of flow holes, in the cross section perpendicular to the direction of flow of the fluid in the flow holes, the flow holes in the central portion has a linear portion are partitioned by the partition wall, the cylindrical portion side, together with the cylindrical contact Keru at least a portion of the flow hole in contact with the shaped portion said partition wall is curved, separated by curved the partition wall portion the flow holes have an area provided continuously, the honeycomb structure central angle formed between the center of the cross section and the area is characterized der Rukoto below 60 ° 30 ° or more were. Which has a plurality of the regions, region of the tubular portion corresponding to the center of each region, the honeycomb structure according to claim 1, characterized in that positioned at equal intervals in the cross section. In the flow hole partitioned by the curved partition wall portion, the partition wall portion extending in the center direction from the outer periphery of the tubular portion is the partition wall portion A, and the partition wall portion connected to the partition wall portion A is the partition wall portion B. The position where the partition wall portion A is connected to the partition wall portion B and the position serving as the starting point of the partition wall portion A extending in the center direction from the partition wall portion B are shifted from each other when viewed in the center direction from the cylindrical portion side. The honeycomb structure according to claim 1 or 2 , characterized in that: A gas treatment apparatus comprising the honeycomb structure according to any one of claims 1 to 3 .

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