JP2012188346A - Method for firing honeycomb mold, honeycomb structure obtained by using the same and gas treating apparatus with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for firing a honeycomb mold where cracks are difficult to generate on a partition part, a sealing material and a cylindrical part.SOLUTION: In the method for firing the honeycomb mold, the honeycomb mold is fired with an inflow port (IF) inderside, the honeycomb mold having a cylindrical part 2 where a fluid flows inside and a plurality of flow holes 5 which are formed by the partition part 3 being arranged in a lattice state at the inside of the cylindrical part 2 and having air permeability and whose inflow port (IF) and outflow port (OF) of the fluid are alternately sealed with the sealing material 4a, 4b, and whose inflow port (IF) has a larger area than that of the outflow port (OF). An auxiliary agent for molding contained in the sealing material 4a is easily defatted because the volume of the sealing material 4a located at the underside becomes smaller than a case that firing is performed in a state that the outflow port (OF) is located at the underside and then the cracks hardly generate on the cylindrical part 2, the partition part 3 and the sealing material 4a located at the underside.

Description

  The present invention captures particulates contained in exhaust gas generated from internal combustion engines, incinerators, boilers, and the like that are power sources for automobiles, generators, hydraulic excavators, wheel loaders, rough terrain cranes, tractors, railway vehicles, and the like. Method of firing honeycomb formed body for obtaining honeycomb structure used for filter for collecting, filter for decomposing and removing harmful substances and the like, honeycomb structure obtained using the same, and gas processing apparatus equipped with the same About.

  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.

  As such a filter, an exhaust gas inlet and an outlet formed by a cylindrical portion through which a fluid flows and a partition wall portion having air permeability arranged in a lattice shape inside the cylindrical portion. In order to suppress the pressure loss of the partition wall that occurs due to the collection of fine particles in the exhaust gas, a honeycomb structure having a plurality of flow holes alternately sealed with a sealing material is used. In order to reduce the thickness and increase the amount of collected fine particles, a honeycomb structure having a structure in which the exhaust gas inlet has a larger area than the outlet is known.

  As a manufacturing method for obtaining such a honeycomb structure, Patent Document 1 describes mixing, kneading, extrusion molding, and drying of ceramic raw material powder, a molding aid, and an additive in order to suppress cracks generated in the firing process. It is disclosed that the open end face of the green ceramic honeycomb structure produced in this way is placed on a firing table made of heat-resistant inorganic powder and fired.

JP 2004-59353 A

  However, in the firing method of the ceramic honeycomb structure proposed in Patent Document 1, when the ceramic honeycomb structure is fired by placing it on the firing table with the outlet of the ceramic honeycomb facing downward, the opposite side of the inlet is provided. Since the portion is sealed with the sealing material, the lower sealing material has a larger volume than the upper sealing material. As a result, there is a problem that cracks are likely to occur in the sealing material, and the generated cracks progress and cracks are likely to occur in the partition wall and the cylindrical portion.

  In view of such problems, the present invention provides a method for firing a honeycomb formed body capable of suppressing the occurrence of cracks, a honeycomb structure obtained using the method, and an exhaust gas treatment apparatus including the honeycomb structure. .

  A method for firing a honeycomb formed body of the present invention is formed by a cylindrical portion in which a fluid flows inside and a partition wall portion having air permeability arranged in a lattice shape inside the cylindrical portion. A honeycomb molded body having a structure in which the outlet has a plurality of flow holes alternately sealed with a sealing material and the inlet has a larger area than the outlet is fired with the inlet facing downward. It is characterized by that.

  In addition, the honeycomb structure of the present invention is obtained by using the method for firing the honeycomb formed body in any one of the above-described configurations.

  In addition, an exhaust gas treatment device of the present invention is characterized by including the honeycomb structure having the above-described configuration.

  According to the method for firing a honeycomb formed body of the present invention, a fluid inlet is formed by a cylindrical portion through which a fluid flows and a partition wall portion having air permeability arranged in a lattice shape inside the cylindrical portion. And a honeycomb molded body having a configuration in which the outlet has a plurality of flow holes alternately sealed with a sealing material and the inlet has a larger area than the outlet, and is fired with the inlet facing downward. Since the volume of the sealing material located on the lower side is smaller than when firing with the outflow port on the lower side, the molding aid contained in this sealing material is degreased even if it is in contact with the firing table. Since it becomes easy, it is hard to produce a crack in a sealing material, and it becomes difficult to produce the crack of the partition part and cylindrical part which generate | occur | produce when the crack progresses.

  Further, according to the honeycomb structure of the present invention, since it is obtained by using the method for firing a honeycomb formed body of the present invention, cracks are unlikely to occur in the sealing material, the cylindrical portion, and the partition wall portion. Reliability can be maintained over a period of time.

  Moreover, according to the gas processing apparatus of the present invention, when the honeycomb structure of the present invention is provided, the gas processing apparatus can be used as a gas processing apparatus that can maintain reliability over a long period of time.

An example of the honeycomb structure obtained by using the method for firing a honeycomb formed body of the present embodiment is schematically shown. (A) is a perspective view, and (b) is a line BB ′ in (a). It is sectional drawing. 1A is a side view showing a part of an end face on the inflow side, and FIG. 2B is a side view showing a part of the end face on the outflow side. FIG. 5 schematically shows another example of a honeycomb structure obtained by using the method for firing a honeycomb formed body of the present embodiment, (a) is a side view showing a part of an end face on the inflow side, and (b) is a side view. It is a side view which shows a part of end surface by the side of an outflow. It is a schematic sectional drawing of the gas treatment apparatus which shows an example of this embodiment typically.

  Hereinafter, an example of a method for firing a honeycomb formed body of the present embodiment, a honeycomb structure obtained by using the method, and a gas processing apparatus including the honeycomb structure will be described.

  FIG. 1 shows an example of a honeycomb structure obtained by using the method for firing a honeycomb formed body of the present embodiment, (a) is a perspective view, and (b) is a BB ′ line in (a). FIG.

  A honeycomb structure 1 of the example shown in FIG. 1 is formed by a cylindrical portion 2 through which a fluid flows, and a partition wall portion 3 having air permeability arranged in a lattice shape inside the cylindrical portion 2. The inflow port (IF) and the outflow port (OF) have a plurality of flow holes 5 that are alternately sealed by the sealing materials 4a and 4b, respectively. The axial direction of the cylindrical portion 2 of the honeycomb structure 1 is indicated by → A (hereinafter referred to as the axial direction A).

Then, the honeycomb structure 1 of the embodiment shown in FIG. 1, for example, an outer diameter of 140～270Mm, the number of circulation holes 5 in the cross section perpendicular to the axial direction A is 5 to 124 per 100 mm ² (. 32 to 800C
PSI). CPSI stands for Cells Per Square Inches.

The honeycomb structure 1 has, for example, a length in the axial direction A of 100 to 250 mm and a cylindricity of 2.5.
It is a cylindrical shape which is not more than mm, and the thickness of the partition wall portion 3 is not less than 0.14 mm and not more than 0.3 mm. In addition, it is preferable that the thickness of the sealing materials 4a and 4b in the axial direction A is 1 mm or more and 5 mm or less.

  Fig. 2 shows the honeycomb structure of the example shown in Fig. 1, (a) is a side view showing a part of the end face on the inflow side, and (b) is a side view showing a part of the end face on the outflow side. is there.

  The honeycomb structure 1 of the example shown in FIG. 2 has a quadrangular shape and an octagonal shape as shown in FIG. (IF) is configured to have a larger area than the outlet (OF).

  FIG. 3 shows another example of a honeycomb structure obtained by using the method for firing a honeycomb formed body of the present embodiment, (a) is a side view showing a part of the end face on the inflow side, and (b) FIG. 4 is a side view showing a part of the end face on the outflow side.

  Further, as shown in FIG. 3A, the honeycomb structure 1 ′ shown in FIG. 3 has a square shape in which both the flow hole 5a sealed on the inflow side and the open flow hole 5b are square. The corners are arc-shaped. As in the honeycomb structure 1 shown in FIG. 2, the inflow port (IF) has a larger area than the outflow port (OF). On the other hand, on the outflow side, as shown in FIG. 2B, the honeycomb structures 1 and 1 ′ shown in FIGS. 2 and 3 are each provided with the inflow side sealed through hole 5a and the inflow side open through hole. 5b is sealed.

  In particular, in the honeycomb structure 1 ′ of the example shown in FIG. 3, the corners of the flow holes 5 b are arcuate, so that cracks that are likely to occur at the corners can be reduced, which is more preferable.

  Further, in the honeycomb structures 1 and 1 ′ shown in FIGS. 2 and 3, the diameter of the flow hole 5 b is preferably 1.30 times or more and 1.95 times or less than the diameter of the flow hole 5 a. Thus, by setting the ratio of the diameters to 1.30 times or more, the respective surface areas of the partition wall 3 and the sealing material 4b that can adsorb the fine particles are increased, so that the amount of collected fine particles can be increased. In addition, since the partition wall portion 3 is not extremely thinned by setting the diameter ratio to 1.95 times or less, the mechanical strength is hardly impaired. Here, the diameters of the flow holes 5a and 5b are the diameters of the inscribed circles in contact with the partition walls 3 of the openings at the end face on the inflow side and the end face on the outflow side, and can be measured using an optical microscope. it can.

  Further, the partition walls 3 of the honeycomb structures 1 and 1 ′ obtained by using the method for firing a honeycomb formed body of the present embodiment have a porosity of 35% by volume to 60% by volume and an average pore diameter of 5 μm. The porous ceramic sintered body preferably has a thickness of 26 μm or less. When the porosity and average pore diameter of the ceramic sintered body forming such partition walls 3 are within this range, an increase in pressure loss can be suppressed while maintaining the mechanical strength of the honeycomb structure 1. Therefore, the average pore diameter and porosity may be obtained in accordance with the mercury intrusion method.

  Specifically, first, a sample for measuring the average pore diameter and the porosity is cut out from the partition wall 3 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% by volume of the cumulative pore volume may be set as the average pore diameter, and the percentage of the cumulative pore volume with respect to the volume of the sample may be used as the porosity.

Further, the tubular part 2, the partition part 3 and the sealing material 4 constituting the honeycomb structure 1, 1 ′ obtained by using the method for firing the honeycomb formed body of the present embodiment are components having a small thermal expansion coefficient, for example, , cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO 2), β- user crypto tight _{(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 ), potassium zirconium phosphate (KZr ₂ (PO ₄ ) ₃ ) or aluminum titanate (Al ₂ TiO ₅ ) as a main component. It is preferable that the partition wall 3 and the sealing material 4 are made of a sintered body mainly composed of aluminum titanate. Since such a sintered body mainly composed of aluminum titanate has high thermal shock resistance, it is deposited on the inner wall surface of the cylindrical portion 2 and the fine particles collected on the wall surface of the partition wall portion 3 and the sealing material 4. In order to regenerate the honeycomb structure 1, 1 ′ by burning the fine particles, the cylindrical portion 2, the partition wall portion 3, and the sealing material 4 can be heated by a burner, a heater or the like to give a sudden temperature change. The occurrence of cracks in can be suppressed.

In particular, when both the cylindrical portion 2, the partition wall portion 3 and the sealing material 4 are 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 This is because the heat resistance, corrosion resistance and heat deterioration resistance of each member are improved.

Further, the cylindrical portion 2, if none partition wall 3 and the sealing member 4 is composed mainly of aluminum titanate (Al 2 _{TiO 5),} the tubular portion 2, each of the partition wall 3 and the sealing member 4 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, the crystal grains adjacent to the grain boundary phase are strongly bonded to each other, and abnormal grain growth of the crystal grains is suppressed. 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 whose composition formula is represented by SiO ₂ has high stability, but the composition formula is SiO _2-x (where x is 0 <x <2). The non-stoichiometric silicon oxide shown may be used.

  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.

  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.

  Moreover, since aluminum oxide also has low corrosion resistance to sulfate, it is preferable that the content be 15% by mass or less with respect to 100% by mass in total of the oxides constituting the grain boundary phase.

The main component in the honeycomb structure of the present embodiment occupies 50% by mass or more with respect to 100% by mass of all components of the sintered body constituting the cylindrical part 2, the partition wall part 3 and the sealing material 4, respectively. It refers to ingredients. The contents of the components constituting the cylindrical portion 2, the partition wall portion 3 and the sealing material 4 can be determined by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission analysis. Specifically, in the case where the main component is aluminum titanate, for titanium oxide and aluminum oxide, the content of each element Ti and Al is measured and the total content converted to oxide is the total content of aluminum titanate. What is necessary is just to set it as content.

  Next, a method for manufacturing a honeycomb structure will be described.

First, 27 to 33% by mass of aluminum oxide powder, 13 to 17% by mass of ferric oxide powder, 7 to 13% by mass of magnesium oxide powder, and the remainder of titanium oxide powder were prepared. A slurry obtained by mixing the preparation raw material with water, acetone or 2-propanol is dried by a spray drying method or the like, and for example, granules having an average particle size of 50 μm or more and 300 μm or less are obtained. 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.

  Next, the obtained granules are 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 pseudo brookite in which elements Ti, Al, Mg and Fe are dissolved in each other are dissolved. A calcined powder made of a type crystal 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 classified into a particle size of 25 μm or less and 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. And a pore-forming agent such as graphite, starch or polyethylene resin whose addition amount is 1 to 13 parts by mass with respect to 100 parts by mass of the calcined powder, and further plasticizer and thickening agent Agents, water and molding aids include, for example, celluloses such as methylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, alcohols such as polyvinyl alcohol, salts such as lignin sulfonate, waxes such as paraffin wax and microcrystalline wax, and ethylene -Vinyl acetate copolymer resin (EVA), polyethylene, polystyrene, liquid crystal poly Chromatography, in addition to thermoplastic resins such as engineering plastics and mixture, this mixture a universal stirrer, was put into a tumbling mill or V-type mixer or the like to prepare a kneaded product. 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 mixture mentioned above is produced.

Next, it shape | molds using an extrusion molding machine. This extrusion molding machine is equipped with a molding die, the inner diameter that determines the outer diameter of the honeycomb molded body is, for example, 155 mm to 300 mm, and has a slit for forming the partition wall portion of the honeycomb molded body. The interval between the slits is set so that the inlet of the molded body has a larger area than the outlet. A clay is put into an extrusion molding machine equipped with this mold, 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 obtained honeycomb formed body is fired. Specifically, it is important to fire the honeycomb formed body in a firing furnace such as an electric furnace or a gas furnace with the inlet facing down on the firing table. This is because, for example, by firing the inlet having a larger area than the outlet in this way, the sealing material with a large volume is on the upper side, and the molding aid contained in this sealing material is Also, it becomes easy to degrease both the upper side of nothing and the flow hole 5 extending downward.

  Thus, when fired using the firing method of the present embodiment, it is formed by a cylindrical portion 2 through which a fluid flows and a partition wall portion 3 having air permeability arranged in a lattice shape inside the cylindrical portion 2. The fluid inflow port (IF) and the outflow port (OF) are provided with a plurality of flow holes 5 alternately sealed by the sealing materials 4a and 4b, respectively, and the inflow port (IF) is from the outflow port (OF). In addition, a honeycomb structure 1, 1 ′ having a large area can be obtained. By using such a firing method, the volume of the sealing material 4a located on the lower side is smaller than when firing with the outlet (OF) on the lower side. The molding aid contained in this sealing material 4a is easily degreased, cracks are less likely to occur in the sealing material 4a located on the lower side, and the cracks are prevented from progressing. 3 is less likely to crack.

  In the case of firing the honeycomb formed body containing the blended raw material, the temperature is set to 1300 ° C. to 1500 ° C. or lower, preferably 1400 ° C. to 1450 ° C., and held for 2 hours to 10 hours.

Next, in the case of obtaining the honeycomb structure 1, 1 ′ composed of a ceramic sintered body in which the main components of the tubular portion 2, the partition wall portion 3 and the sealing material 4 are all 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 structures 1, 1 ′ are the same as the case where the main component is aluminum titanate except that the firing temperature is changed from 1300 ° C. to 1500 ° C. to 1350 ° C. to 1450 ° C. .

  In particular, the honeycomb formed body is mounted on a firing table via a plate-shaped member having the same component as the main component constituting the honeycomb formed body and containing a volatile substance at 6% by mass or less. Baking is preferred.

  A plate-like member having the same component as the main component constituting the honeycomb molded body and containing a volatile substance at 6% by mass or less exhibits the same shrinkage behavior as that of the honeycomb molded body in the firing step. As shown, the honeycomb structures 1 and 1 ′ having high cylindricity can be obtained, and the mounting to the gas processing apparatus 10 can be facilitated.

  Further, color unevenness may occur inside the sintered body obtained by firing the honeycomb formed body, and cracks may be generated at the location where the color unevenness occurs. In the present embodiment, although the reason is not clear, when the plate-like body used when firing the honeycomb formed body contains a volatile substance at 6% by mass or less, the honeycomb sintered body is placed inside the honeycomb sintered body. The resulting color unevenness can be reduced, and the occurrence of inner cracks can be suppressed.

In addition, it is suitable that content of the volatile substance contained in a plate-shaped member is 0.5 mass% or more. When the content of the volatile substance contained in the plate-shaped member is within this range, the powders forming the plate-shaped member are strongly bonded to each other, so that the shape retention of the plate-shaped member is increased and the handling is facilitated.

  Here, the volatile substance means an organic component contained in the plate-like member (for example, pore-forming agent such as graphite, starch or polyethylene resin, celluloses such as methylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, alcohol such as polyvinyl alcohol). , Salts such as lignin sulfonate, waxes such as paraffin wax and microcrystalline wax, and molding aids such as thermoplastic resins such as ethylene-vinyl acetate copolymer resin (EVA), polyethylene, polystyrene, liquid crystal polymer, engineering plastics, etc. , Alcohols such as glycerin, caprylic acid, lauric acid, palmitic acid, higher fatty acids such as alginic acid, oleic acid and stearic acid, stearic acid metal salts such as aluminum stearate, Oxyalkylene alkyl ethers and other plasticizers that give lubricity, and thickeners such as cellulose, chitin, and chitansan gum) and moisture that absorbs moisture. Volatile substances are GC / MS analysis methods (gas chromatography) Identification and quantification by mass spectrometry).

  Moreover, content of a volatile substance can be calculated | required using the following formula | equation (1).

Volatile content = (W ₀ −W ₁ ) / W ₀ × 100 (%)
(W ₀ : Mass of the plate-shaped member after molding (g) W ₁ : Mass (g) of the plate-shaped member after degreasing in a nitrogen atmosphere at temperatures and holding times of 500 ° C. and 5.5 hours, respectively.
The main component constituting the honeycomb formed body refers to a component occupying more than 50% by mass with respect to 100% by mass of the component constituting the honeycomb formed body. The content of each component can be determined by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission analysis. Specifically, in the case where the main component is aluminum titanate, for titanium oxide and aluminum oxide, the content of each element Ti and Al is measured and the total content converted to oxide is the total content of aluminum titanate. What is necessary is just to set it as content.

Here, the plate-like member is preferably provided with pores communicating from the surface facing the honeycomb formed body to the surface facing the firing table, and particularly preferably a honeycomb-shaped formed body. . When the plate-like member has a honeycomb shape, for example, the outer diameter and the thickness are 147 mm each.
The number of holes in a cross section perpendicular to the axial direction A in FIG. 1 is 5 to 124 per 100 mm ² (32 to 800 CPSI). In particular, the plate-like member has a thickness of 10 mm or more, so that the shrinkage behavior of the honeycomb formed body and the shrinkage behavior of the plate-like member are closer, and the thickness is 20 mm or less, the plate-like member is Since it is discarded after firing, the amount of waste can be reduced. The plate-like member has a partition wall thickness of, for example, not less than 0.147 mm and not more than 0.221 mm. In addition, a plate-shaped member can also be formed combining two or more, In this case, it is suitable to use a plate-shaped member piled up and down.

The plate-like member preferably has a sodium and calcium content of 0.1% by mass or less. When the content of each of these metal components is within this range, when the honeycomb formed body is fired, it is possible to suppress the amount of sodium and calcium that lowers the corrosion resistance from diffusing into the honeycomb formed body. It can suppress that the corrosion resistance in the end surface by the side of the plate-shaped member falls. The contents of these metal components can be determined by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission analysis.

Further, the honeycomb formed body is placed in a state in which a powder mainly composed of aluminum oxide, aluminum nitride, calcium oxide, boron nitride, zirconium oxide, magnesium oxide or magnesium aluminate is in contact with the end face of the inlet (IF). Is preferable. Since these components have a high melting point, the honeycomb formed body has a honeycomb-like plate-like member at the inlet (IF).
Since the reaction with the honeycomb-like plate-like member does not proceed and it becomes difficult to fix as compared with the case where it is placed in contact with the end face, the fired honeycomb structures 1 and 1 ′ can be easily handled. Even when the honeycomb formed body is placed directly on the firing table, the honeycomb structure 1, 1 ′ is fired after firing by placing the powder in contact with the end face of the inlet (IF). Since it becomes difficult to adhere to the firing table, the honeycomb structures 1, 1 ′ after firing become easy to handle.

In addition, the main component in the said powder means the component which occupies 98 mass% or more with respect to 100 mass% of all the components which comprise a powder, and it is especially suitable that it is 99 mass% or more. When occupying 98% by mass or more with respect to 100% by mass of all the components constituting the powder, the melting point of the powder is difficult to be lowered, so that the sticking suppression effect is further enhanced. The main component constituting the powder is identified by X-ray diffraction, and the content of the main component is determined by fluorescent X-ray analysis or ICP (Inductively Coupled Plasma) emission analysis. it can.

Further, when the shape of the plate-shaped member is a disk shape, the ratio of the outer diameter of the plate-shaped member to the outer diameter of the honeycomb formed body is preferably 85% or more and 115% or less. More preferably the ratio is 85%
More than 100%. When the plate-shaped member is in such a shape range, the honeycomb molded body can be placed on the plate-shaped member in a range that does not become unstable, and the plate-shaped member is accompanied by firing shrinkage of the honeycomb molded body. As a result, the frictional resistance that occurs is reduced, making it difficult for cracks to form in the honeycomb formed body.

  Further, in the method for firing the honeycomb formed body of the present embodiment, it is preferable that a heat insulating member is disposed around the tubular portion so as to be in contact with the tubular portion.

  If the heat insulating member is disposed around the tubular portion so as to be in contact with the tubular portion, the rate of temperature increase on the tubular portion side of the honeycomb formed body is suppressed, so the pore forming agent contained in the honeycomb formed body , The rapid vaporization of the plasticizer, thickener and molding aid is suppressed, and cracks caused by this rapid vaporization are less likely to occur.

  Such a heat insulating member is preferably made of a heat-resistant inorganic fiber from the viewpoint that the degree of freedom in arrangement becomes high according to the shape of the honeycomb formed body. Examples of the heat-resistant inorganic fiber include silica fiber, aluminosilicate fiber, alumina fiber, aluminoborosilicate fiber, carbon fiber, zirconia fiber, silicon nitride fiber, silicon carbide fiber, and mullite fiber.

  Since the honeycomb structure 1, 1 ′ manufactured using such a manufacturing method has a smaller volume of the sealing material 4a located on the lower side than when firing with the outflow port on the lower side, Since the molding aid contained in the sealing material 4a is easily degreased, cracks are hardly generated in the sealing material 4a, and the cracks are prevented from progressing, and cracks are hardly generated in the partition wall portion 3 and the cylindrical portion 2. Become. As a result, the honeycomb structures 1 and 1 ′ can maintain reliability over a long period of time even when heat during regeneration is repeatedly applied after collecting the fine particles.

  Next, an example of a gas processing apparatus provided with the honeycomb structure of the present embodiment will be described.

  FIG. 4 is a schematic cross-sectional view of a gas processing apparatus schematically showing an example of this embodiment.

In the gas processing apparatus 10 of the example shown in FIG. 4, the honeycomb structure 1 of the present embodiment is accommodated in the case 7 with the outer periphery held by the heat insulating material layer 6, and the exhaust gas (EG) inlet 8a. And exhaust pipes 9a and 9b are connected to the discharge port 8b, respectively. The heat insulating material layer 6 is formed of at least one of ceramic fiber, glass fiber, carbon fiber, and ceramic whisker, for example. The case 7 is made of, for example, SUS303, SU
It is made of stainless steel such as S304 and SUS316, and has a central portion formed in a cylindrical shape and both end portions formed in a truncated cone shape.

  An internal combustion engine (not shown) such as a diesel engine or a gasoline engine is connected to the exhaust gas inflow side of the gas processing device 10 through an exhaust pipe 9a. When the internal combustion engine is operated and exhaust gas is supplied to the case 7 through the exhaust pipe 9a, the exhaust gas is introduced into the flow holes 5b of the honeycomb structure 1 and is sealed by the sealing material 4b. The outflow is blocked. The exhaust gas from which the outflow is blocked passes through the partition wall 3 having air permeability and is introduced into the adjacent flow hole 5a. When the exhaust gas passes through the partition wall 3, particulates in the exhaust gas are collected on the wall surfaces of the partition wall 3 and the pore surfaces of the partition wall 3. The exhaust gas in which the particulates are collected is discharged from the circulation hole 5a in a purified state, and is discharged to the outside through the exhaust pipe 9b.

In the gas processing apparatus 10 of the example shown in FIG. 4, a catalyst may be supported on the wall surface of the partition wall portion 3 of the honeycomb structure 1. The supported catalyst includes a catalyst for oxidizing and burning fine particles in exhaust gas and a catalyst for oxidizing nitrogen monoxide (NO) in exhaust gas to generate nitrogen dioxide (NO ₂ ). Any one of these catalysts may be supported on the wall surface of the partition wall 3, and it is more preferable that both catalysts are supported.

  Catalysts for oxidizing and burning fine particles in the exhaust gas include, for example, platinum group metals such as ruthenium, rhodium, palladium, osmium, iridium, platinum and their oxides, gold, silver, copper, etc. It is preferable to consist of at least one of group metals and vanadium oxide. If such a catalyst is supported on the wall surface of the partition wall 3, the catalyst oxidizes and burns the particulates in the exhaust gas, so the particulates can be burned and removed at a lower temperature than when not supported. The occurrence of melting damage and cracks in the partition wall 3 can be further reduced.

As an example of nitrogen oxide (NOx) in exhaust gas, catalysts for oxidizing nitric oxide (NO) are, for example, ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-23, It is preferable to comprise at least one of MCM zeolite, mordenite, faujasite, ferrierite and zeolite beta. By supporting such a catalyst on the wall surface of the partition wall portion 3, nitrogen monoxide (NO) contained in the exhaust gas is oxidized into nitrogen dioxide (NO ₂ ) and released. Note that the released nitrogen dioxide (NO ₂ ) can be reduced to nitrogen by ammonia. Thus, the exhaust gas purification performance can be improved by supporting the catalyst for oxidizing nitric oxide (NO) in the exhaust gas on the wall surface of the partition wall 3.

  These catalysts may be supported on at least one of the wall surface of the partition wall 3 and the surface of the pores of the partition wall 3.

  Further, in order to increase the contact area between the catalyst supported on the wall surface and the exhaust gas, a powder having a large specific surface area such as γ alumina, δ alumina, and θ alumina is supported on the wall surface of the partition wall 3 as a support. It is advisable to support the catalyst after that.

  In order to obtain such a honeycomb structure 1, 1 ′ carrying a catalyst on the wall surface of the partition wall portion 3, the honeycomb structure 1, 1 ′ obtained by the above-described manufacturing method is used as a catalyst, for example, ruthenium. , Rhodium, palladium, osmium, iridium and platinum group metals such as soluble salts, polyvinyl alcohol and other binders and water, and then immersed in a slurry at a temperature of 100 ° C to 150 ° C for 1 hour or more. What is necessary is just to dry by hold | maintaining for 48 hours or less. And after making it dry, the honeycomb structure 1,1 'which carry | supported the catalyst on the wall surface of the partition part 3 can be obtained by heat-processing at the temperature of 600 degreeC or more and 700 degrees C or less 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 3 and the surface of the pores of the partition wall 3 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.

  For example, when the gas processing apparatus 10 of the present embodiment includes the honeycomb structure 1 which is an example of the present embodiment, the collection efficiency is higher, and the honeycomb structures 1 and 1 ′ are cracked. 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, thus saving space. Can also be realized.

  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.

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

First, the aluminum oxide powder is 30% by mass, the ferric oxide powder is 14% by mass, the magnesium oxide powder is 10% by mass, and the titanium oxide powder is 46% by mass. The slurry mixed together is dried by spray drying, and the average particle size is 175
Granules that were μm were obtained. Here, each powder of aluminum oxide, ferric oxide, magnesium oxide, and titanium oxide was a powder having a purity of 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. Then, with respect to 100 parts by mass of the classified calcined powder, an addition amount is 2.5 parts by mass, a silicon oxide powder having an average particle diameter of 2 μm, and a polyethylene as a pore-forming agent having an addition amount of 7 parts by mass. After the resin was added, a plasticizer, a thickener, water, and methyl cellulose as a molding aid were further added to form 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, a sealing material for alternately sealing each of the inflow side and the outflow side of the plurality of flow holes of the cut molded body was produced. Specifically, first, the end surface on the outflow side was masked in a checkered pattern so that a portion sealed by the sealing material was formed, and the end surface was immersed in a slurry for providing the sealing material. In addition, the flow hole that is not masked is provided with a tip portion coated with water-repellent resin from the end surface side on the inflow side, and a pin with a flat tip portion is inserted in advance, The slurry that entered the outflow side of the flow hole 5b was dried at room temperature to form a sealing material on the outflow side of the molded body. Then, the pin is pulled out, the same operation as described above is performed on the inflow side of the molded body, and a sealing material is formed to form a cylindrical portion in which fluid flows inside, and a lattice shape inside the cylindrical portion. And a plurality of flow holes 5 in which the fluid inlet and outlet are alternately sealed with a sealing material, and the area of the inlet is larger than that of the outlet. A honeycomb formed body having a wide structure was obtained.

Next, in the electric furnace, 20 honeycomb molded bodies are fired on the firing table for each sample with the inlets in the direction shown in Table 1 to fire the outer diameter, height, and partition wall 3. The number of flow holes 5 in the cross section perpendicular to the thickness and the axial direction A is 144 mm, 152 mm, and 0.2 mm, respectively.
, 300CPI of honeycomb structure sample No. 1-15 were obtained. At this time, the diameter of the flow hole 5b sealed on the outlet side is 1.4 times the diameter of the flow hole 5a, and the porosity and average pore diameter of the partition wall 3 are 44 for each sample. %, 14 μm.

Sample No. 2 to 14 are composed of the same main component as the main component constituting the honeycomb molded body, and are placed on the firing table via the honeycomb plate member, and the volatile substance contained in the plate member is Manufacturer: Shimadzu Corporation Name: Gas Chromatograph Mass Spectrometer Standard: Measured using GC / MS analysis method using QP5000, and its content is calculated separately using Equation (1). The values obtained and the number of plate-like members are shown in Table 1. When a plurality of plate members were used, the plate members were stacked one above the other, and the honeycomb formed body was placed thereon and fired.

  The outer diameter and height of each plate-like member, the thickness of the partition wall 3 and the number of flow holes in the cross section perpendicular to the axial direction A were 151 mm, 12 mm, 0.21 mm, and 300 CPI, respectively.

  And the crack by the side of an inlet was observed visually for every sample, and the ratio of the number by which the crack was observed was shown in Table 1 in percentage.

  Sample No. One sample was extracted for each sample from 1 to 14, and the cylindricity was measured using calipers. Specifically, the outer diameter of the cross section at the center position in the A-axis direction of the sample in FIG. 1 and the outer diameters of the end faces on both sides are measured using calipers, and the difference between the maximum value and the minimum value is defined as cylindricity. It is shown in Table 1.

As can be seen from the results shown in Table 1, Sample No. 1 to 14 are formed by a cylindrical portion through which a fluid flows, and a partition wall portion having air permeability arranged in a lattice shape inside the cylindrical portion, and the fluid inlet and outlet are made of a sealing material. Since the honeycomb molded body having a plurality of flow holes sealed alternately and having an inflow port having a larger area than the outflow port is obtained by firing the inflow port on the lower side, Since the molding aid contained in the sealing material on the inlet side is easily degreased, cracks generated in the sealing material are suppressed more than the sample No. 15 obtained by firing with the inlet facing upward. It can be seen that the cracks are also prevented from progressing and cracks are less likely to occur in the partition wall portion and the cylindrical portion.

  In particular, sample no. 2-14, because the same component as the component constituting the honeycomb molded body is mounted on the firing table via the honeycomb-shaped plate-shaped member having the same component as the main component, the same component as the component constituting the honeycomb molded body is the main component. Since the honeycomb-like plate-like member exhibits the same shrinkage behavior as that of the honeycomb formed body in the firing step, it is understood that a honeycomb structure having a high cylindricity is obtained.

  Sample No. Nos. 7 to 13 are placed in a state where the powder mainly composed of aluminum oxide, aluminum nitride, calcium oxide, boron nitride, zirconium oxide, magnesium oxide or magnesium aluminate is in contact with the end face of the inlet (IF). Therefore, the reaction with the honeycomb-shaped plate-like member did not proceed and it was difficult to adhere, so that the fired honeycomb structure could be easily handled.

  Sample No. Since 1-4 and 6-14 contain 6 mass% or less of the volatile substance contained in a plate-shaped member, sample No. which contains a volatile substance exceeding 6 mass%. Compared to 5, it was found that the ratio of the number of observed cracks could be kept low.

Sample No. 1 prepared in Example 1 was used. Samples 1 to 14 that were not cracked visually were individually installed in the gas treatment device 10, and the engine speed was set to 3000 min ⁻¹ and 50 N · m, respectively, and the engine was operated for a predetermined time. Then, exhaust gas was introduced into the gas processing apparatus 10 to collect fine particles. Next, assuming that the engine speed is 4000 min ⁻¹ and the temperature of each sample reaches 700 ° C., the engine speed is changed to 1050 min ⁻¹ and the torque is changed to 30 N · m to burn the fine particles. A durability test was conducted. This exhaust gas introduction, particulate collection and combustion operations are repeated every time the particulate collection amount increases by 0.1 mg / cm ³ , and the amount of particulate collection until cracking occurs is determined. It is shown in Table 2. A larger value of the collected amount of fine particles means that cracks are less likely to occur and the durability of the honeycomb structure is excellent. The combustion of the fine particles is that an oxidation catalyst is arranged on the front side of the honeycomb structure, light oil is sprayed into the exhaust gas and burned with the oxidation catalyst, and the exhaust gas heated by this combustion is introduced into the honeycomb structure. The method was used.

  As can be seen from the results shown in Table 2, the sample No. 1 to 14, since the honeycomb structure is used in the gas treatment apparatus, after the firing, the sealing material 4, the partition wall part 3 and the cylindrical part 2 are less prone to crack, the fine particles are efficiently collected, It can be said that it can be used efficiently over a long period of time.

1: Honeycomb structure 2: Cylindrical part 3: Partition part 4: Sealing material 5: Flow hole 6: Heat insulating material layer 7: Case 8a: Exhaust gas (EG) inlet 8b: Exhaust gas (EG) exhaust Outlet 9: exhaust pipe
10: Exhaust gas treatment equipment

Claims (5)

  A plurality of flow holes formed by a cylindrical portion and a partition wall portion having air permeability arranged inside the cylindrical portion in a lattice shape, and the fluid inlet and outlet are alternately sealed with a sealing material And firing the honeycomb molded body having a configuration in which the inlet has a larger area than the outlet, with the inlet facing downward.   The honeycomb formed body is placed on a firing table through a plate-shaped member having the same component as the main component constituting the honeycomb formed body as a main component and containing 6% by mass or less of a volatile substance. The method for firing a honeycomb formed body according to claim 1, wherein the firing is performed.   The method for firing a honeycomb formed body according to claim 1 or 2, wherein a heat insulating member is disposed around the tubular portion so as to be in contact with the tubular portion.   A honeycomb structure obtained by using the firing method according to any one of claims 1 to 3.   A gas processing apparatus comprising the honeycomb structure according to claim 4.

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