WO2010146954A1 - Ceramic filter for supporting a catalyst, and manufacturing method therefor - Google Patents

Ceramic filter for supporting a catalyst, and manufacturing method therefor Download PDF

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Publication number
WO2010146954A1
WO2010146954A1 PCT/JP2010/058271 JP2010058271W WO2010146954A1 WO 2010146954 A1 WO2010146954 A1 WO 2010146954A1 JP 2010058271 W JP2010058271 W JP 2010058271W WO 2010146954 A1 WO2010146954 A1 WO 2010146954A1
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Prior art keywords
ceramic filter
catalyst
supporting
aluminum titanate
sintered body
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PCT/JP2010/058271
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French (fr)
Japanese (ja)
Inventor
伸樹 糸井
宏仁 森
隆寛 三島
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大塚化学株式会社
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Publication of WO2010146954A1 publication Critical patent/WO2010146954A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2425—Honeycomb filters characterized by parameters related to the physical properties of the honeycomb structure material
    • B01D46/24494—Thermal expansion coefficient, heat capacity or thermal conductivity
    • B01J35/56—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • B01D39/2068—Other inorganic materials, e.g. ceramics
    • B01D39/2072—Other inorganic materials, e.g. ceramics the material being particulate or granular
    • B01D39/2075—Other inorganic materials, e.g. ceramics the material being particulate or granular sintered or bonded by inorganic agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2425—Honeycomb filters characterized by parameters related to the physical properties of the honeycomb structure material
    • B01D46/2429—Honeycomb filters characterized by parameters related to the physical properties of the honeycomb structure material of the honeycomb walls or cells
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2451—Honeycomb filters characterized by the geometrical structure, shape, pattern or configuration or parameters related to the geometry of the structure
    • B01D46/2455—Honeycomb filters characterized by the geometrical structure, shape, pattern or configuration or parameters related to the geometry of the structure of the whole honeycomb or segments
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2451—Honeycomb filters characterized by the geometrical structure, shape, pattern or configuration or parameters related to the geometry of the structure
    • B01D46/2482—Thickness, height, width, length or diameter
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
    • C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
    • C04B35/478—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on aluminium titanates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/0006—Honeycomb structures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0471—Surface coating material
    • B01D2239/0478—Surface coating material on a layer of the filter
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    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00793—Uses not provided for elsewhere in C04B2111/00 as filters or diaphragms
    • C—CHEMISTRY; METALLURGY
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    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/0081—Uses not provided for elsewhere in C04B2111/00 as catalysts or catalyst carriers
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3206—Magnesium oxides or oxide-forming salts thereof
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3217—Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3232—Titanium oxides or titanates, e.g. rutile or anatase
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    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3418—Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
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    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/42—Non metallic elements added as constituents or additives, e.g. sulfur, phosphor, selenium or tellurium
    • C04B2235/428—Silicon
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    • C04B2235/9607—Thermal properties, e.g. thermal expansion coefficient

Definitions

  • the present invention relates to a catalyst-supporting ceramic filter using aluminum titanate and a method for producing the same.
  • Aluminum titanate is expected to be a porous material used in automobile exhaust gas treatment catalyst carriers, diesel particulate filters (DPFs), etc. because of its low thermal expansion, excellent thermal shock resistance, and high melting point. Development is underway.
  • Patent Document 1 an aluminum titanate sintered body having high strength and less mechanical strength deterioration with respect to repeated thermal history is obtained without impairing the high melting point and low thermal expansion property of aluminum titanate. Therefore, it has been proposed to sinter aluminum titanate added with magnesium oxide and silicon oxide.
  • Patent Document 2 discloses that an exhaust gas filter is manufactured using columnar aluminum titanate, and when the longitudinal direction of the columnar particles has a negative thermal expansion coefficient, the direction perpendicular to the longitudinal direction is positive thermal expansion. It has been proposed to manufacture an exhaust gas filter that has a coefficient or a negative thermal expansion coefficient in the direction perpendicular to the longitudinal direction when the longitudinal direction of the columnar particles has a positive thermal expansion coefficient.
  • a film made of inorganic fine particles such as alumina is provided on the surface of the ceramic filter in order to increase the specific surface area.
  • the inorganic fine particle film is generally formed by applying a solution containing inorganic fine particles.
  • the inorganic fine particles enter the structural minute cracks of aluminum titanate. There was a problem.
  • the microcrack contributes to the low thermal expansibility of aluminum titanate. When inorganic fine particles enter the microcrack, there is a problem that the low thermal expansibility of aluminum titanate cannot be obtained.
  • Patent Document 3 in order to solve the above-described problem, before the inorganic fine particle film is provided, a precoat treatment is performed, and the precoat is filled in the minute cracks of the aluminum titanate, so that the inorganic fine particles are formed. It has been proposed to prevent entry into microcracks.
  • An object of the present invention is to provide a ceramic filter for supporting a catalyst that can obtain a low thermal expansion coefficient without requiring a pre-coating treatment before forming an inorganic fine particle film, and a method for producing the same.
  • the ceramic filter body is formed using aluminum titanate having an average aspect ratio of 1.3 or more.
  • aluminum titanate having an average aspect ratio of 1.3 or more it has a low thermal expansion coefficient even when an inorganic fine particle film is directly provided on the surface of the ceramic filter body without forming a precoat film.
  • a ceramic filter for supporting a catalyst can be obtained.
  • the aluminum titanate used for forming the ceramic filter body is a columnar aluminum titanate having an average aspect ratio of 1.3 or more.
  • the average aspect ratio of the aluminum titanate used in the present invention is more preferably 1.5 or more, and the upper limit value of the average aspect ratio is not particularly limited, but is generally 5 or less.
  • the inorganic fine particle film provided on the surface of the ceramic filter body is preferably in the range of 5 to 50 parts by weight, more preferably in the range of 10 to 30 parts by weight with respect to 100 parts by weight of the ceramic filter body. .
  • Examples of the inorganic fine particles forming the inorganic fine particle film include alumina and zirconia.
  • the average particle size of the inorganic fine particles is preferably in the range of 0.1 to 5 ⁇ m.
  • the inorganic fine particle film can be formed by applying a solution such as a sol containing inorganic fine particles.
  • the catalyst-supporting ceramic filter of the present invention can be used with a catalyst such as silver supported on the surface thereof.
  • the number average minor axis diameter of the columnar aluminum titanate is preferably 10 ⁇ m or less.
  • the number average minor axis diameter is more preferably in the range of 5 to 10 ⁇ m.
  • the number average major axis diameter is preferably in the range of 7 to 17 ⁇ m.
  • the number average major axis diameter and the number average minor axis diameter of the columnar aluminum titanate can be measured by, for example, a flow type particle image analyzer.
  • a method for producing the columnar aluminum titanate of the present invention there is a method comprising a step of mixing a raw material containing a titanium source, an aluminum source and a magnesium source while pulverizing them into mechanochemicals, and a step of firing the pulverized mixture.
  • a method for producing the columnar aluminum titanate of the present invention there is a method comprising a step of mixing a raw material containing a titanium source, an aluminum source and a magnesium source while pulverizing them into mechanochemicals, and a step of firing the pulverized mixture.
  • the temperature for firing the pulverized mixture is preferably a temperature in the range of 1300 to 1600 ° C. By firing within such a temperature range, the columnar aluminum titanate of the present invention can be produced more efficiently.
  • Calcination time is not particularly limited, but it is preferably performed within a range of 0.5 hours to 20 hours.
  • Mechanochemical crushing includes a method of crushing while giving a physical impact. Specifically, pulverization by a vibration mill can be mentioned. By pulverizing with a vibration mill, the disruption of atomic arrangement and the decrease in interatomic distance occur simultaneously due to the shear stress caused by the grinding of the mixed powder, resulting in atomic movement of the contact part of different particles, resulting in a metastable phase. Can be obtained. Thereby, a pulverized mixture with high reaction activity is obtained, and the columnar aluminum titanate of the present invention can be produced by firing the pulverized mixture with high reaction activity.
  • the mechanochemical pulverization in the present invention is generally performed as a dry process without using water or a solvent.
  • the mixing treatment time by mechanochemical pulverization is not particularly limited, but generally it is preferably within the range of 0.1 to 6 hours.
  • the raw materials used in the present invention include a titanium source, an aluminum source, and a magnesium source.
  • a titanium source a compound containing titanium oxide can be used. Specific examples include titanium oxide, rutile ore, titanium hydroxide wet cake, and hydrous titania.
  • the aluminum source a compound that generates aluminum oxide by heating can be used.
  • Specific examples include aluminum oxide, aluminum hydroxide, and aluminum sulfate. Among these, aluminum oxide is particularly preferably used.
  • magnesium source a compound that generates magnesium oxide by heating can be used, and specific examples include magnesium hydroxide, magnesium oxide, and magnesium carbonate. Among these, magnesium hydroxide and magnesium oxide are particularly preferably used.
  • the magnesium source is preferably contained in the raw material so as to be within the range of 0.5 to 2.0% by weight in terms of the respective oxides with respect to the total of the titanium source and the aluminum source. If it is less than 0.5% by weight, a sintered body having a low coefficient of thermal expansion and high mechanical strength may not be obtained. On the other hand, if it exceeds 2.0% by weight, columnar aluminum titanate having an average aspect ratio of 1.3 or more may not be obtained.
  • the raw material may further contain a silicon source.
  • Examples of the silicon source include silicon oxide and silicon. Among these, silicon oxide is particularly preferably used.
  • the content of the silicon source in the raw material is preferably in the range of 0.5 to 10% by weight in terms of the respective oxides with respect to the total of the titanium source and the aluminum source. By setting it within such a range, columnar aluminum titanate can be more stably produced.
  • the thermal expansion coefficient between 30 and 800 ° C. in the extrusion direction of the ceramic filter body is 0.5 ⁇ 10 ⁇ 6 / ° C. or less, and the C-axis crystal orientation ratio with respect to the extrusion direction is 0.75.
  • the above is preferable.
  • the thermal expansion coefficient is 0.5 ⁇ 10 ⁇ 6 / ° C. or less, it is possible to obtain characteristics excellent in thermal shock resistance.
  • the lower limit value of the thermal expansion coefficient is not particularly limited, but is generally at least ⁇ 1.0 ⁇ 10 ⁇ 6 / ° C.
  • the thermal expansion coefficient in the extrusion direction can be reduced.
  • the crystal orientation ratio of the C axis with respect to the filter body extrusion direction in the present invention can be obtained from the following equation.
  • C-axis crystal orientation ratio in the filter body extrusion direction A / (A + B)
  • A: C-axis orientation in the filter body extrusion direction I 002 / (I 002 + I 230 )
  • B: Degree of C-axis orientation in the vertical direction of the filter body I 002 / (I 002 + I 230 )
  • I 002 and I 230 are the extrusion surface for extrusion direction, the peak intensity of the (002) plane when the X-ray diffraction vertical plane in the vertical direction (I 002) and (230) plane peak intensity (I 230 ).
  • the C axis extends along the longitudinal direction of the columnar body. For this reason, when the filter body is extruded, the C-axis is aligned in the extrusion direction, so that the thermal expansion coefficient in the extrusion direction can be lowered.
  • the method for producing a ceramic filter for supporting a catalyst comprises a step of producing a ceramic filter body by extruding and then firing the raw material containing the columnar aluminum titanate, and an inorganic material on the surface of the ceramic filter body. And a step of forming a fine particle film.
  • the raw material containing aluminum titanate can be prepared by adding, for example, a pore-forming agent, a binder, a dispersant, and water to aluminum titanate.
  • This raw material is molded into a honeycomb structure using, for example, an extrusion molding machine, plugged on one side so that the cell openings have a checkered pattern, and then dried to obtain a molded body obtained.
  • the ceramic filter body can be manufactured by firing. Examples of the firing temperature include 1400 to 1600 ° C.
  • Examples of pore-forming agents include graphite, graphite, wood powder, and polyethylene.
  • Examples of the binder include methyl cellulose, ethyl cellulose, and polyvinyl alcohol.
  • Examples of the dispersant include fatty acid soap and ethylene glycol. The amount of pore-forming agent, binder, dispersant, and water can be adjusted as appropriate.
  • an inorganic fine particle film is formed on the surface of the ceramic filter body.
  • the inorganic fine particle film can be formed by applying a solution containing inorganic fine particles.
  • the film containing inorganic fine particles include a sol solution.
  • a ceramic filter for supporting a catalyst having a low coefficient of thermal expansion can be obtained without requiring a precoat treatment before forming an inorganic fine particle film.
  • FIG. 1 is a scanning electron micrograph showing columnar aluminum titanate obtained in an example according to the present invention.
  • FIG. 2 is a perspective view showing the honeycomb sintered body.
  • FIG. 3 is a perspective view showing a measurement sample cut out from the honeycomb sintered body.
  • FIG. 4 is a schematic diagram for explaining a method for measuring the bending strength of a honeycomb sintered body.
  • FIG. 5 is a perspective view showing a measurement sample cut out from the honeycomb sintered body.
  • FIG. 6 is a perspective view showing a honeycomb sintered body.
  • FIG. 7 is a perspective view showing a measurement sample for measuring the X-ray diffraction of the extruded surface cut out from the honeycomb sintered body.
  • FIG. 8 is a perspective view showing a honeycomb sintered body.
  • FIG. 9 is a perspective view showing a measurement sample for measuring X-ray diffraction of a vertical plane cut out from the honeycomb sintered body.
  • FIG. 10 is an X-ray diffraction chart of the columnar aluminum titanate obtained in Example 1 according to the present invention.
  • Example 1 [Production of aluminum titanate] 360.0 g of titanium oxide, 411.1 g of aluminum oxide, 9.7 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
  • FIG. 1 is an SEM photograph showing the aluminum titanate obtained in this example. As shown in FIG. 1, it can be seen that the aluminum titanate obtained in this example has a columnar shape.
  • FIG. 10 is a view showing an X-ray diffraction chart of aluminum titanate obtained in this example.
  • honeycomb sintered body Using the aluminum titanate obtained in the above example, a honeycomb sintered body was manufactured as follows.
  • the obtained clay is extruded to form a honeycomb structure with an extrusion molding machine, and then dried with a hot air dryer, and then the resulting molded body is fired at 1500 ° C. to form a ceramic filter body.
  • a honeycomb sintered body was obtained.
  • FIG. 2 is a perspective view showing the honeycomb sintered body. As shown in FIG. 2, the honeycomb sintered body 1 has 8 ⁇ 8 cells, and the end surface 1a has a size of 1.8 cm in length and 1.8 cm in width. An arrow A indicates the extrusion direction, and an arrow B indicates a direction perpendicular to the extrusion direction A.
  • the porosity was measured by cutting a portion corresponding to 2 ⁇ 2 cells from the center portion 2 of the above 8 ⁇ 8 cell honeycomb sintered body 1 so that the length along the extrusion direction A was about 2 cm. It was.
  • FIG. 3 is a perspective view showing the measurement sample 3. Using the measurement sample 3 shown in FIG. 3, the porosity was measured according to JIS R1634.
  • the length along the extrusion direction A from the central portion 2 of the 8 ⁇ 8 cell honeycomb sintered body 1 is about 2 cm. It cut out so that it might become, and it was set as the measurement sample 3. As shown in FIG. 5, the linear expansion coefficient in the extrusion direction A of the measurement sample 3 was measured according to JIS R1618.
  • Crystal orientation ratio The C-axis crystal orientation ratio of the obtained honeycomb sintered body was measured as the crystal orientation ratio.
  • the crystal orientation ratio was calculated from the crystal orientation degree in the extrusion direction and the crystal orientation degree in the direction perpendicular to the extrusion direction (vertical crystal orientation degree) as shown in the following formula.
  • Crystal orientation ratio Crystal orientation in extrusion direction / (Crystal orientation in extrusion direction + Crystal orientation in vertical direction)
  • the degree of crystal orientation was determined by X-ray diffraction.
  • the crystal orientation degree in the vertical direction was calculated by measuring X-ray diffraction of the vertical surface of the honeycomb sintered body and obtaining I (002) and I (230) in the same manner as described above.
  • 6 and 7 are perspective views showing the production of a measurement sample for measuring the X-ray diffraction of the extruded surface.
  • the region 4 including the end face 1a of the honeycomb sintered body 1 was cut out to prepare a measurement sample shown in Fig. 7.
  • the measurement sample 5 shown in FIG. 7 the X-ray diffraction of the extruded surface 5a of the measurement sample 5 was measured.
  • FIG 8 and 9 are perspective views showing the production of a sample for measuring X-ray diffraction on a vertical plane, that is, a plane perpendicular to the extrusion plane.
  • a region 6 corresponding to 8 ⁇ 2 cells of the honeycomb sintered body 1 was cut out along the extrusion direction A to obtain a measurement sample 7 shown in FIG.
  • the measurement of the X-ray diffraction of the surface (extruded surface) 7a along the extrusion direction A of the measurement sample 7 was performed.
  • the (002) plane is a plane perpendicular to the C axis, and the high strength of the (002) plane means that the C axis is oriented.
  • honeycomb sintered body (ceramic filter main body) was dipped in alumina sol, then pulled up and dried at 110 ° C. for 3 hours. Then, it baked at 500 degreeC with the electric furnace for 1 hour, and formed the alumina coating film on the surface of a honeycomb sintered compact.
  • the formed alumina coating film was 15 parts by weight with respect to 100 parts by weight of the honeycomb sintered body in terms of Al 2 O 3 . Therefore, the alumina coating amount was 15% by weight.
  • the alumina sol was prepared by stirring a slurry of 25% by weight of alumina, 10% by weight of water-soluble cellulose and 65% by weight of deionized water for 1 hour.
  • the average particle size of alumina was 0.15 ⁇ m.
  • the thermal expansion coefficient of the catalyst-supporting ceramic filter obtained as described above was measured in the same manner as described above. The measurement results are shown in Table 1.
  • Example 2 [Production of aluminum titanate] 354.7 g of titanium oxide, 405.0 g of aluminum oxide, 21.3 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
  • honeycomb sintered bodies Using the aluminum titanate obtained in the above example, a honeycomb sintered body was produced in the same manner as in Example 1, and the obtained honeycomb sintered body was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
  • Example 1 [Production of aluminum titanate and honeycomb sintered body] A honeycomb sintered body (ceramic filter body) was manufactured in the same manner as in Example 1 by using aluminum titanate obtained in the same manner as in Example 1.
  • honeycomb sintered body (ceramic filter main body) was immersed in a 10% by weight polyvinyl alcohol aqueous solution, taken out, dried at 110 ° C. for 3 hours, and precoated.
  • the polymer coating film was formed so that the amount of the polymer coating film as the precoat treatment was 5 parts by weight with respect to 100 parts by weight of the honeycomb sintered body. Therefore, the polymer coating amount is 5% by weight.
  • the honeycomb sintered body subjected to the pre-coating treatment was immersed in alumina sol in the same manner as in Example 1 to form an alumina coating, and a catalyst-supporting ceramic filter was produced.
  • the coefficient of thermal expansion of the obtained catalyst-carrying ceramic filter was measured in the same manner as described above, and the measurement results are shown in Table 1.
  • Example 2 The honeycomb sintered body obtained in Example 2 was pre-coated in the same manner as in Comparative Example 1, and then an alumina coating film was formed to produce a catalyst-supporting ceramic filter.
  • honeycomb sintered bodies A honeycomb sintered body was manufactured and evaluated in the same manner as in Example 1 except that the aluminum titanate obtained in this comparative example was used.
  • the thermal expansion coefficient of the catalyst-supporting ceramic filter was measured, and the measurement results are shown in Table 1.
  • Comparative Example 4 A honeycomb sintered body was manufactured in the same manner as in Comparative Example 3. The resulting honeycomb sintered body was pre-coated in the same manner as in Comparative Example 1, and then an alumina coating film was formed to produce a catalyst-supporting ceramic filter.
  • Table 1 shows the coefficient of thermal expansion of the ceramic filter for catalyst support.
  • the catalyst-supporting ceramic filters of Examples 1 and 2 according to the present invention have a thermal expansion coefficient close to 0, which is a preferable thermal expansion coefficient as a catalyst-supporting ceramic filter, without performing pre-coating treatment. Is shown. This is because, by using columnar aluminum titanate having an aspect ratio of 1.3 or more, the thermal expansion coefficient in the extrusion direction of the ceramic filter body can be lowered, so that micro cracks of the aluminum titanate (microcracks) This is because even if alumina enters, a low thermal expansion coefficient close to 0 can be obtained.
  • Honeycomb sintered body (ceramic filter body) DESCRIPTION OF SYMBOLS 1a ... End face of honeycomb sintered body 2 ... Center part of honeycomb sintered body 3 ... Measurement sample cut out from honeycomb sintered body 4 ... Area near end face of honeycomb sintered body 5 ... Extruded surface of honeycomb sintered body X Sample for measuring line diffraction 5a ... extruded surface 6 ... 8 ⁇ 2 cell region of honeycomb sintered body 7 ... Sample for measuring X-ray diffraction of vertical surface of honeycomb sintered body 7a ... vertical surface 10 ... pressing bar 11,12 ... support point

Abstract

Disclosed is a ceramic filter for supporting a catalyst, whereby a low thermal expansion coefficient can be obtained without requiring precoating before inorganic particulate film formation. Also disclosed is a method for manufacturing said ceramic filter. The disclosed ceramic filter for supporting a catalyst on the filter surface is characterized by the provision of: a ceramic filter body formed from an aluminum titanate having a mean aspect ratio (the number average long-axis length divided by the number average short-axis length) of at least 1.3; and an inorganic particulate film provided directly on the surface of the ceramic filter body in order to increase the specific surface area thereof.

Description

触媒担持用セラミックフィルタ及びその製造方法Ceramic filter for supporting catalyst and method for manufacturing the same
　本発明は、チタン酸アルミニウムを用いた触媒担持用セラミックフィルタ及びその製造方法に関するものである。 The present invention relates to a catalyst-supporting ceramic filter using aluminum titanate and a method for producing the same.
　チタン酸アルミニウムは、低熱膨張性で耐熱衝撃性に優れ、かつ融点が高いため、自動車の排ガス処理用触媒担体や、ディーゼルパティキュレートフィルタ（ＤＰＦ）等に用いられる多孔質材料として期待され、種々の開発が行われている。 Aluminum titanate is expected to be a porous material used in automobile exhaust gas treatment catalyst carriers, diesel particulate filters (DPFs), etc. because of its low thermal expansion, excellent thermal shock resistance, and high melting point. Development is underway.
　特許文献１においては、チタン酸アルミニウムが有する高融点、低熱膨張性を損なうことなく、高強度を有し、繰り返しの熱履歴に対して機械的強度の劣化が少ないチタン酸アルミニウム焼結体を得るため、チタン酸アルミニウムに、酸化マグネシウム及び酸化ケイ素を添加したものを焼結することが提案されている。 In Patent Document 1, an aluminum titanate sintered body having high strength and less mechanical strength deterioration with respect to repeated thermal history is obtained without impairing the high melting point and low thermal expansion property of aluminum titanate. Therefore, it has been proposed to sinter aluminum titanate added with magnesium oxide and silicon oxide.
　特許文献２においては、柱状チタン酸アルミニウムを用いて排ガスフィルタを製造することが開示されており、柱状粒子の長手方向が負の熱膨張係数であるとき長手方向と垂直な方向が正の熱膨張係数であるか、あるいは柱状粒子の長手方向が正の熱膨張係数であるとき長手方向と垂直な方向が負の熱膨張係数である排ガスフィルタを製造することが提案されている。 Patent Document 2 discloses that an exhaust gas filter is manufactured using columnar aluminum titanate, and when the longitudinal direction of the columnar particles has a negative thermal expansion coefficient, the direction perpendicular to the longitudinal direction is positive thermal expansion. It has been proposed to manufacture an exhaust gas filter that has a coefficient or a negative thermal expansion coefficient in the direction perpendicular to the longitudinal direction when the longitudinal direction of the columnar particles has a positive thermal expansion coefficient.
　しかしながら、柱状チタン酸アルミニウムの具体的な製造方法については開示されていない。 However, a specific method for producing columnar aluminum titanate is not disclosed.
　チタン酸アルミニウムからなるセラミックフィルタを触媒担持用セラミックフィルタとして用いる場合、比表面積を高めるため、セラミックフィルタの表面にアルミナなどの無機微粒子からなる膜を設けることが行われている。無機微粒子膜は、無機微粒子を含有する溶液を塗布することにより、一般に形成されているが、このような無機微粒子膜を設けると、チタン酸アルミニウムの構造的微少亀裂内に、無機微粒子が入り込むという問題があった。微少亀裂は、チタン酸アルミニウムの低熱膨張性に寄与するものであり、微少亀裂内に無機微粒子が入り込むと、チタン酸アルミニウムが有する低熱膨張性を得ることができないという問題があった。 When a ceramic filter made of aluminum titanate is used as a catalyst-supporting ceramic filter, a film made of inorganic fine particles such as alumina is provided on the surface of the ceramic filter in order to increase the specific surface area. The inorganic fine particle film is generally formed by applying a solution containing inorganic fine particles. However, when such an inorganic fine particle film is provided, the inorganic fine particles enter the structural minute cracks of aluminum titanate. There was a problem. The microcrack contributes to the low thermal expansibility of aluminum titanate. When inorganic fine particles enter the microcrack, there is a problem that the low thermal expansibility of aluminum titanate cannot be obtained.
　特許文献３においては、上記のような問題を解消するため、無機微粒子膜を設ける前に、プレコート処理を施し、チタン酸アルミニウムの微少亀裂内にプレコートを予め充填させておくことにより、無機微粒子が微少亀裂内に入り込むのを防止することが提案されている。 In Patent Document 3, in order to solve the above-described problem, before the inorganic fine particle film is provided, a precoat treatment is performed, and the precoat is filled in the minute cracks of the aluminum titanate, so that the inorganic fine particles are formed. It has been proposed to prevent entry into microcracks.
　しかしながら、このようなプレコート処理を施すことにより、触媒担持用セラミックフィルタの生産効率が低下するという問題がある。 However, there is a problem that the production efficiency of the catalyst-supporting ceramic filter is reduced by performing such pre-coating treatment.
特開平１－２４９６５７号公報JP-A-1-249657 特開平９－２９０２３号公報JP-A-9-29023 特表２００７－５２６１１７号公報Special table 2007-526117
　本発明の目的は、無機微粒子膜形成前のプレコート処理を必要とすることなく、低い熱膨張係数が得られる触媒担持用セラミックフィルタ及びその製造方法を提供することある。 An object of the present invention is to provide a ceramic filter for supporting a catalyst that can obtain a low thermal expansion coefficient without requiring a pre-coating treatment before forming an inorganic fine particle film, and a method for producing the same.
　本発明は、表面に触媒を担持するための触媒担持用セラミックフィルタであって、平均アスペクト比（＝個数平均長軸径／個数平均短軸径）が１．３以上であるチタン酸アルミニウムから形成されたセラミックフィルタ本体と、セラミックフィルタ本体の比表面積を高めるためセラミックフィルタ本体の表面上に直接設けられる無機微粒子膜とを備えることを特徴としている。 The present invention is a ceramic filter for supporting a catalyst for supporting a catalyst on the surface, formed from aluminum titanate having an average aspect ratio (= number average major axis diameter / number average minor axis diameter) of 1.3 or more. And an inorganic fine particle film directly provided on the surface of the ceramic filter body in order to increase the specific surface area of the ceramic filter body.
　本発明の触媒担持用セラミックフィルタにおいては、平均アスペクト比が１．３以上であるチタン酸アルミニウムを用いて、セラミックフィルタ本体を形成している。平均アスペクト比が１．３以上であるチタン酸アルミニウムを用いることにより、セラミックフィルタ本体の表面に、プレコート膜を形成することなく、無機微粒子膜を直接設けた場合にも、低い熱膨張係数を有する触媒担持用セラミックフィルタとすることができる。 In the catalyst-supporting ceramic filter of the present invention, the ceramic filter body is formed using aluminum titanate having an average aspect ratio of 1.3 or more. By using aluminum titanate having an average aspect ratio of 1.3 or more, it has a low thermal expansion coefficient even when an inorganic fine particle film is directly provided on the surface of the ceramic filter body without forming a precoat film. A ceramic filter for supporting a catalyst can be obtained.
　本発明においてセラミックフィルタ本体を形成するために用いるチタン酸アルミニウムは、平均アスペクト比が１．３以上である柱状チタン酸アルミニウムである。本発明において用いるチタン酸アルミニウムの平均アスペクト比は、さらに好ましくは１．５以上であり、平均アスペクト比の上限値は、特に限定されないが、一般には５以下である。平均アスペクト比の高いチタン酸アルミニウムを用いることにより、触媒担持用セラミックフィルタの熱膨張係数をより低くすることができるとともに、セラミックフィルタの強度を高めることができる。 In the present invention, the aluminum titanate used for forming the ceramic filter body is a columnar aluminum titanate having an average aspect ratio of 1.3 or more. The average aspect ratio of the aluminum titanate used in the present invention is more preferably 1.5 or more, and the upper limit value of the average aspect ratio is not particularly limited, but is generally 5 or less. By using aluminum titanate having a high average aspect ratio, the thermal expansion coefficient of the ceramic filter for supporting a catalyst can be further lowered, and the strength of the ceramic filter can be increased.
　セラミックフィルタ本体の表面上に設ける無機微粒子膜は、セラミックフィルタ本体１００重量部に対し、５～５０重量部の範囲内であることが好ましく、１０～３０重量部の範囲内であることがさらに好ましい。 The inorganic fine particle film provided on the surface of the ceramic filter body is preferably in the range of 5 to 50 parts by weight, more preferably in the range of 10 to 30 parts by weight with respect to 100 parts by weight of the ceramic filter body. .
　無機微粒子膜を形成する無機微粒子としては、アルミナ、ジルコニアなどが挙げられる。無機微粒子の平均粒子径としては、０．１～５μｍの範囲であることが好ましい。 Examples of the inorganic fine particles forming the inorganic fine particle film include alumina and zirconia. The average particle size of the inorganic fine particles is preferably in the range of 0.1 to 5 μm.
　無機微粒子膜は、無機微粒子を含むゾルなどの溶液を塗布することにより形成することができる。 The inorganic fine particle film can be formed by applying a solution such as a sol containing inorganic fine particles.
　本発明の触媒担持用セラミックフィルタは、その表面に銀などの触媒を担持して用いることができる。 The catalyst-supporting ceramic filter of the present invention can be used with a catalyst such as silver supported on the surface thereof.
　本発明において、柱状チタン酸アルミニウムの個数平均短軸径は、１０μｍ以下であることが好ましい。個数平均短軸径は、５～１０μｍの範囲内であることがさらに好ましい。また、個数平均長軸径は、７～１７μｍの範囲内であることが好ましい。 In the present invention, the number average minor axis diameter of the columnar aluminum titanate is preferably 10 μm or less. The number average minor axis diameter is more preferably in the range of 5 to 10 μm. The number average major axis diameter is preferably in the range of 7 to 17 μm.
　柱状チタン酸アルミニウムの個数平均長軸径及び個数平均短軸径は、例えば、フロー式粒子像分析装置により測定することができる。 The number average major axis diameter and the number average minor axis diameter of the columnar aluminum titanate can be measured by, for example, a flow type particle image analyzer.
　本発明の柱状チタン酸アルミニウムを製造する方法としては、チタン源、アルミニウム源、及びマグネシウム源を含む原料をメカノケミカルに粉砕しながら混合する工程と、粉砕した混合物を焼成する工程とを備える方法が挙げられる。 As a method for producing the columnar aluminum titanate of the present invention, there is a method comprising a step of mixing a raw material containing a titanium source, an aluminum source and a magnesium source while pulverizing them into mechanochemicals, and a step of firing the pulverized mixture. Can be mentioned.
　チタン源、アルミニウム源、及びマグネシウム源を含む原料を、ケミカルに粉砕しながら混合した粉砕混合物を用い、この粉砕混合物を焼成することにより、平均アスペクト比が１．３以上である柱状のチタン酸アルミニウムを製造することができる。 Columnar aluminum titanate having an average aspect ratio of 1.3 or more by firing a pulverized mixture obtained by mixing raw materials including a titanium source, an aluminum source, and a magnesium source while chemically pulverizing the pulverized mixture. Can be manufactured.
　粉砕混合物を焼成する温度としては、１３００～１６００℃の範囲内の温度であることが好ましい。このような温度範囲内で焼成することにより、本発明の柱状チタン酸アルミニウムをより効率的に製造することができる。 The temperature for firing the pulverized mixture is preferably a temperature in the range of 1300 to 1600 ° C. By firing within such a temperature range, the columnar aluminum titanate of the present invention can be produced more efficiently.
　焼成時間は、特に限定されるものではないが、０．５時間～２０時間の範囲内で行うことが好ましい。 Calcination time is not particularly limited, but it is preferably performed within a range of 0.5 hours to 20 hours.
　メカノケミカルな粉砕としては、物理的な衝撃を与えながら粉砕する方法が挙げられる。具体的には、振動ミルによる粉砕が挙げられる。振動ミルによる粉砕処理を行うことにより、混合粉体の摩砕による剪断応力によって、原子配列の乱れと原子間距離の減少が同時に起こり、異種粒子の接点部分の原子移動が起こる結果、準安定相が得られると考えられる。これにより、反応活性の高い粉砕混合物が得られ、この反応活性の高い粉砕混合物を焼成することにより、上記本発明の柱状チタン酸アルミニウムを製造することができる。 Mechanochemical crushing includes a method of crushing while giving a physical impact. Specifically, pulverization by a vibration mill can be mentioned. By pulverizing with a vibration mill, the disruption of atomic arrangement and the decrease in interatomic distance occur simultaneously due to the shear stress caused by the grinding of the mixed powder, resulting in atomic movement of the contact part of different particles, resulting in a metastable phase. Can be obtained. Thereby, a pulverized mixture with high reaction activity is obtained, and the columnar aluminum titanate of the present invention can be produced by firing the pulverized mixture with high reaction activity.
　本発明におけるメカノケミカルな粉砕は、一般に、水や溶剤を用いない乾式処理として行われる。 The mechanochemical pulverization in the present invention is generally performed as a dry process without using water or a solvent.
　メカノケミカルな粉砕による混合処理の時間は特に限定されるものではないが、一般には０．１時間～６時間の範囲内であることが好ましい。 The mixing treatment time by mechanochemical pulverization is not particularly limited, but generally it is preferably within the range of 0.1 to 6 hours.
　本発明において用いる原料には、チタン源、アルミニウム源、及びマグネシウム源が含まれる。チタン源としては、酸化チタンを含有する化合物を用いることができ、具体的には、酸化チタン、ルチル鉱石、水酸化チタンウェットケーキ、含水チタニアなどが挙げられる。 The raw materials used in the present invention include a titanium source, an aluminum source, and a magnesium source. As the titanium source, a compound containing titanium oxide can be used. Specific examples include titanium oxide, rutile ore, titanium hydroxide wet cake, and hydrous titania.
　アルミニウム源としては、加熱により酸化アルミニウムを生じる化合物を用いることができ、具体的には、酸化アルミニウム、水酸化アルミニウム、硫酸アルミニウムなどが挙げられる。これらの中でも、特に酸化アルミニウムが好ましく用いられる。 As the aluminum source, a compound that generates aluminum oxide by heating can be used. Specific examples include aluminum oxide, aluminum hydroxide, and aluminum sulfate. Among these, aluminum oxide is particularly preferably used.
　チタン源とアルミニウム源の混合割合としては、Ｔｉ：Ａｌ＝１：２（モル比）の割合を基本とするが、それぞれ±１０％程度であれば変化させても支障はない。 The mixing ratio of the titanium source and the aluminum source is basically a ratio of Ti: Al = 1: 2 (molar ratio), but there is no problem even if it is changed within about ± 10%.
　マグネシウム源としては、加熱により酸化マグネシウムを生じる化合物を用いることができ、具体的には、水酸化マグネシウム、酸化マグネシウム、炭酸マグネシウムなどが挙げられる。これらの中でも、特に水酸化マグネシウム及び酸化マグネシウムが好ましく用いられる。 As the magnesium source, a compound that generates magnesium oxide by heating can be used, and specific examples include magnesium hydroxide, magnesium oxide, and magnesium carbonate. Among these, magnesium hydroxide and magnesium oxide are particularly preferably used.
　マグネシウム源は、チタン源及びアルミニウム源の合計に対してそれぞれの酸化物換算で０．５～２．０重量％の範囲内となるように原料中に含まれていることが好ましい。０．５重量％未満であると、低い熱膨張係数及び高い機械的強度を有する焼結体が得られない場合がある。また、２．０重量％より多くなると、平均アスペクト比が１．３以上である柱状チタン酸アルミニウムが得られない場合がある。 The magnesium source is preferably contained in the raw material so as to be within the range of 0.5 to 2.0% by weight in terms of the respective oxides with respect to the total of the titanium source and the aluminum source. If it is less than 0.5% by weight, a sintered body having a low coefficient of thermal expansion and high mechanical strength may not be obtained. On the other hand, if it exceeds 2.0% by weight, columnar aluminum titanate having an average aspect ratio of 1.3 or more may not be obtained.
　また、本発明の製造方法においては、原料中にケイ素源がさらに含まれていても良い。 Further, in the production method of the present invention, the raw material may further contain a silicon source.
　ケイ素源が含有させることにより、チタン酸アルミニウムの分解を抑制することができ、高温安定性に優れた柱状チタン酸アルミニウムを製造することができる。 By including the silicon source, decomposition of aluminum titanate can be suppressed, and columnar aluminum titanate excellent in high-temperature stability can be produced.
　ケイ素源としては、酸化ケイ素、ケイ素などが挙げられる。これらの中でも、特に酸化ケイ素が好ましく用いられる。ケイ素源の原料中における含有量は、チタン源及びアルミニウム源の合計に対してそれぞれの酸化物換算で、０．５～１０重量％の範囲内であることが好ましい。このような範囲内とすることにより、柱状チタン酸アルミニウムをより安定して製造することができる。 Examples of the silicon source include silicon oxide and silicon. Among these, silicon oxide is particularly preferably used. The content of the silicon source in the raw material is preferably in the range of 0.5 to 10% by weight in terms of the respective oxides with respect to the total of the titanium source and the aluminum source. By setting it within such a range, columnar aluminum titanate can be more stably produced.
　本発明においては、セラミックフィルタ本体の押出方向における３０～８００℃の間の熱膨張係数が０．５×１０－６／℃以下であり、上記押出方向に対するＣ軸の結晶配向比が０．７５以上であることが好ましい。熱膨張係数が０．５×１０－６／℃以下であることにより、耐熱衝撃性に優れた特性を得ることができる。熱膨張係数の下限値は、特に限定されるものではないが、一般に－１．０×１０－６／℃以上である。 In the present invention, the thermal expansion coefficient between 30 and 800 ° C. in the extrusion direction of the ceramic filter body is 0.5 × 10 −6 / ° C. or less, and the C-axis crystal orientation ratio with respect to the extrusion direction is 0.75. The above is preferable. When the thermal expansion coefficient is 0.5 × 10 −6 / ° C. or less, it is possible to obtain characteristics excellent in thermal shock resistance. The lower limit value of the thermal expansion coefficient is not particularly limited, but is generally at least −1.0 × 10 −6 / ° C.
　上記押出方向に対するＣ軸の結晶配向比が０．７５以上であることにより、上記押出方向における熱膨張係数を小さくすることができる。 When the crystal orientation ratio of the C axis with respect to the extrusion direction is 0.75 or more, the thermal expansion coefficient in the extrusion direction can be reduced.
　本発明におけるフィルタ本体押出方向に対するＣ軸の結晶配向比は、以下の式から求めることができる。 The crystal orientation ratio of the C axis with respect to the filter body extrusion direction in the present invention can be obtained from the following equation.
　フィルタ本体押出方向のＣ軸の結晶配向比＝Ａ／（Ａ＋Ｂ）
　Ａ：フィルタ本体押出方向のＣ軸配向度＝Ｉ００２／（Ｉ００２＋Ｉ２３０）
　Ｂ：フィルタ本体垂直方向のＣ軸配向度＝Ｉ００２／（Ｉ００２＋Ｉ２３０） C-axis crystal orientation ratio in the filter body extrusion direction = A / (A + B)
A: C-axis orientation in the filter body extrusion direction = I 002 / (I 002 + I 230 )
B: Degree of C-axis orientation in the vertical direction of the filter body = I 002 / (I 002 + I 230 )
　Ｉ００２及びＩ２３０は、押出方向については押出面を、垂直方向については垂直面をＸ線回折したときの（００２）面のピーク強度（Ｉ００２）及び（２３０）面のピーク強度（Ｉ２３０）である。 I 002 and I 230 are the extrusion surface for extrusion direction, the peak intensity of the (002) plane when the X-ray diffraction vertical plane in the vertical direction (I 002) and (230) plane peak intensity (I 230 ).
　本発明の柱状チタン酸アルミニウムは、柱状体の長手方向に沿ってＣ軸が延びている。このため、フィルタ本体を押出成形した際、押出方向にＣ軸が整列するため、押出方向の熱膨張係数を低くすることができる。 In the columnar aluminum titanate of the present invention, the C axis extends along the longitudinal direction of the columnar body. For this reason, when the filter body is extruded, the C-axis is aligned in the extrusion direction, so that the thermal expansion coefficient in the extrusion direction can be lowered.
　本発明の触媒担持用セラミックフィルタを製造する方法は、上記柱状のチタン酸アルミニウムを含む原料を押出成形した後、焼成することによりセラミックフィルタ本体を作製する工程と、セラミックフィルタ本体の表面上に無機微粒子膜を形成する工程とを備えることを特徴としている。 The method for producing a ceramic filter for supporting a catalyst according to the present invention comprises a step of producing a ceramic filter body by extruding and then firing the raw material containing the columnar aluminum titanate, and an inorganic material on the surface of the ceramic filter body. And a step of forming a fine particle film.
　チタン酸アルミニウムを含む原料は、チタン酸アルミニウムに、例えば、造孔剤、バインダー、分散剤、及び水を添加して調製することができる。この原料を、例えば押出成形機を用いてハニカム構造体となるように成形し、セルの開口が市松模様となるように片側の目封止を行った後、乾燥して得られた成形体を焼成し、セラミックフィルタ本体を作製することができる。焼成温度としては、例えば、１４００～１６００℃が挙げられる。 The raw material containing aluminum titanate can be prepared by adding, for example, a pore-forming agent, a binder, a dispersant, and water to aluminum titanate. This raw material is molded into a honeycomb structure using, for example, an extrusion molding machine, plugged on one side so that the cell openings have a checkered pattern, and then dried to obtain a molded body obtained. The ceramic filter body can be manufactured by firing. Examples of the firing temperature include 1400 to 1600 ° C.
　造孔剤としては、黒鉛、グラファイト、木粉、ポリエチレンが挙げられる。また、バインダーとしては、メチルセルロース、エチルセルロース、ポリビニルアルコールが挙げられる。分散剤としては、脂肪酸石鹸、エチレングリコールが挙げられる。造孔剤、バインダー、分散剤、及び水の量は適宜調整することができる。 Examples of pore-forming agents include graphite, graphite, wood powder, and polyethylene. Examples of the binder include methyl cellulose, ethyl cellulose, and polyvinyl alcohol. Examples of the dispersant include fatty acid soap and ethylene glycol. The amount of pore-forming agent, binder, dispersant, and water can be adjusted as appropriate.
　セラミックフィルタ本体を作製した後、セラミックフィルタ本体の表面上に無機微粒子膜を形成する。無機微粒子膜は、例えば上述のように、無機微粒子を含む溶液を塗布することにより、形成するとことができる。無機微粒子を含む膜としては、ゾル溶液などが挙げられる。 After producing the ceramic filter body, an inorganic fine particle film is formed on the surface of the ceramic filter body. For example, as described above, the inorganic fine particle film can be formed by applying a solution containing inorganic fine particles. Examples of the film containing inorganic fine particles include a sol solution.
　本発明によれば、無機微粒子膜形成前のプレコート処理を必要とすることなく、低い熱膨張係数を有する触媒担持用セラミックフィルタが得られる。 According to the present invention, a ceramic filter for supporting a catalyst having a low coefficient of thermal expansion can be obtained without requiring a precoat treatment before forming an inorganic fine particle film.
図１は、本発明に従う実施例において得られた柱状チタン酸アルミニウムを示す走査型電子顕微鏡写真である。FIG. 1 is a scanning electron micrograph showing columnar aluminum titanate obtained in an example according to the present invention. 図２は、ハニカム焼結体を示す斜視図である。FIG. 2 is a perspective view showing the honeycomb sintered body. 図３は、ハニカム焼結体から切り出した測定サンプルを示す斜視図である。FIG. 3 is a perspective view showing a measurement sample cut out from the honeycomb sintered body. 図４は、ハニカム焼結体の曲げ強度の測定方法を説明するための模式図である。FIG. 4 is a schematic diagram for explaining a method for measuring the bending strength of a honeycomb sintered body. 図５は、ハニカム焼結体から切り出した測定サンプルを示す斜視図である。FIG. 5 is a perspective view showing a measurement sample cut out from the honeycomb sintered body. 図６は、ハニカム焼結体を示す斜視図である。FIG. 6 is a perspective view showing a honeycomb sintered body. 図７は、ハニカム焼結体から切り出した押出面のＸ線回折を測定するための測定サンプルを示す斜視図である。FIG. 7 is a perspective view showing a measurement sample for measuring the X-ray diffraction of the extruded surface cut out from the honeycomb sintered body. 図８は、ハニカム焼結体を示す斜視図である。FIG. 8 is a perspective view showing a honeycomb sintered body. 図９は、ハニカム焼結体から切り出した垂直面のＸ線回折を測定するための測定サンプルを示す斜視図である。FIG. 9 is a perspective view showing a measurement sample for measuring X-ray diffraction of a vertical plane cut out from the honeycomb sintered body. 図１０は、本発明に従う実施例１で得られた柱状チタン酸アルミニウムのＸ線回折チャートを示す図である。FIG. 10 is an X-ray diffraction chart of the columnar aluminum titanate obtained in Example 1 according to the present invention.
　以下、本発明を具体的な実施例により詳細に説明するが、本発明は以下の実施例に限定されるものではない。 Hereinafter, the present invention will be described in detail with specific examples, but the present invention is not limited to the following examples.
　（実施例１）
　〔チタン酸アルミニウムの製造〕
　酸化チタン３６０．０ｇ、酸化アルミニウム４１１．１ｇ、水酸化マグネシウム９．７ｇ、及び酸化ケイ素１９．０ｇを振動ミルにて粉砕しながら、２．０時間混合した。 Example 1
[Production of aluminum titanate]
360.0 g of titanium oxide, 411.1 g of aluminum oxide, 9.7 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
　以上のようにして得られた粉砕混合物５００ｇをルツボに充填し、電気炉にて１５００℃で４時間焼成した。 500 g of the pulverized mixture obtained as described above was charged in a crucible and baked at 1500 ° C. for 4 hours in an electric furnace.
　得られた生成物について、Ｘ線回折にて結晶相を同定した。また得られた生成物について、走査型電子顕微鏡（ＳＥＭ）にて形状を確認し、フロー式粒子像分析にてアスペクト比（＝個数平均長軸径／個数平均短軸径）を測定した。測定結果を表１に示す。 The crystal phase of the obtained product was identified by X-ray diffraction. Further, the shape of the obtained product was confirmed with a scanning electron microscope (SEM), and the aspect ratio (= number average major axis diameter / number average minor axis diameter) was measured by flow particle image analysis. The measurement results are shown in Table 1.
　図１は、本実施例において得られたチタン酸アルミニウムを示すＳＥＭ写真である。図１において示すように、本実施例において得られたチタン酸アルミニウムが柱状形状を有することがわかる。 FIG. 1 is an SEM photograph showing the aluminum titanate obtained in this example. As shown in FIG. 1, it can be seen that the aluminum titanate obtained in this example has a columnar shape.
　図１０は、本実施例において得られたチタン酸アルミニウムのＸ線回折チャートを示す図である。 FIG. 10 is a view showing an X-ray diffraction chart of aluminum titanate obtained in this example.
　〔ハニカム焼結体の製造〕
　上記実施例で得られたチタン酸アルミニウムを用いて、以下のようにしてハニカム焼結体を製造した。 [Manufacture of honeycomb sintered body]
Using the aluminum titanate obtained in the above example, a honeycomb sintered body was manufactured as follows.
　チタン酸アルミニウム１００重量部に対し、黒鉛２０重量部、メチルセルロース１０重量部、脂肪酸石鹸０．５重量部を配合し、さらに水を適当量添加して混練し、押出成形可能な坏土を得た。 Compounding 20 parts by weight of graphite, 10 parts by weight of methyl cellulose and 0.5 parts by weight of fatty acid soap with respect to 100 parts by weight of aluminum titanate, adding an appropriate amount of water and kneading to obtain an extrudable clay. .
　得られた坏土を押出成形機にてハニカム構造体となるように押し出して成形し、次に熱風乾燥機で乾燥した後、得られた成形体を１５００℃で焼成し、セラミックフィルタ本体であるハニカム焼結体を得た。 The obtained clay is extruded to form a honeycomb structure with an extrusion molding machine, and then dried with a hot air dryer, and then the resulting molded body is fired at 1500 ° C. to form a ceramic filter body. A honeycomb sintered body was obtained.
　〔ハニカム焼結体の評価〕
　得られたハニカム焼結体について気孔率、曲げ強度、熱膨張係数、及び結晶配向比を以下のようにして測定した。 [Evaluation of honeycomb sintered body]
With respect to the obtained honeycomb sintered body, the porosity, bending strength, thermal expansion coefficient, and crystal orientation ratio were measured as follows.
　（気孔率）
　図２は、ハニカム焼結体を示す斜視図である。図２に示すように、ハニカム焼結体１は、８×８セルを有し、端面１ａは、縦１．８ｃｍ、横１．８ｃｍの大きさを有している。矢印Ａは、押出方向を示しており、矢印Ｂは押出方向Ａに対し垂直な方向を示している。 (Porosity)
FIG. 2 is a perspective view showing the honeycomb sintered body. As shown in FIG. 2, the honeycomb sintered body 1 has 8 × 8 cells, and the end surface 1a has a size of 1.8 cm in length and 1.8 cm in width. An arrow A indicates the extrusion direction, and an arrow B indicates a direction perpendicular to the extrusion direction A.
　気孔率は、上記の８×８セルのハニカム焼結体１の中心部２から、２×２セルに相当する部分を、押出方向Ａに沿う長さが２ｃｍ程度となるように切り出し、測定サンプルとした。 The porosity was measured by cutting a portion corresponding to 2 × 2 cells from the center portion 2 of the above 8 × 8 cell honeycomb sintered body 1 so that the length along the extrusion direction A was about 2 cm. It was.
　図３は、測定サンプル３を示す斜視図である。図３に示す測定サンプル３を用い、ＪＩＳ　Ｒ１６３４に準拠して気孔率を測定した。 FIG. 3 is a perspective view showing the measurement sample 3. Using the measurement sample 3 shown in FIG. 3, the porosity was measured according to JIS R1634.
　（曲げ強度）
　図４に示すように、上記の８×８セルのハニカム焼結体１を、支持点１１及び１２に支持した状態で、焼結体１の中心部を押圧棒１０で押圧することにより、ＪＩＳ　Ｒ１６０１に準拠して、曲げ強度を測定した。 (Bending strength)
As shown in FIG. 4, the 8 × 8 cell honeycomb sintered body 1 is supported by the support points 11 and 12, and the center portion of the sintered body 1 is pressed with a pressing rod 10, thereby JIS. The bending strength was measured according to R1601.
　（熱膨張係数）
　図２及び図３を参照して説明した、気孔率の測定サンプル３と同様にして、８×８セルのハニカム焼結体１の中心部２から、押出方向Ａに沿う長さが２ｃｍ程度となるように切り出し、測定サンプル３とした。図５に示すように、測定サンプル３の押出方向Ａにおける線膨張係数を、ＪＩＳ　Ｒ１６１８に準拠して測定した。 (Coefficient of thermal expansion)
Similar to the porosity measurement sample 3 described with reference to FIGS. 2 and 3, the length along the extrusion direction A from the central portion 2 of the 8 × 8 cell honeycomb sintered body 1 is about 2 cm. It cut out so that it might become, and it was set as the measurement sample 3. As shown in FIG. 5, the linear expansion coefficient in the extrusion direction A of the measurement sample 3 was measured according to JIS R1618.
　（結晶配向比）
　得られたハニカム焼結体についてのＣ軸結晶配向比を、結晶配向比とした測定した。 (Crystal orientation ratio)
The C-axis crystal orientation ratio of the obtained honeycomb sintered body was measured as the crystal orientation ratio.
　結晶配向比は、以下の式に示すように、押出方向の結晶配向度と、押出方向と垂直な方向の結晶配向度（垂直方向の結晶配向度）から算出した。 The crystal orientation ratio was calculated from the crystal orientation degree in the extrusion direction and the crystal orientation degree in the direction perpendicular to the extrusion direction (vertical crystal orientation degree) as shown in the following formula.
　結晶配向比＝押出方向の結晶配向度／（押出方向の結晶配向度＋垂直方向の結晶配向度） Crystal orientation ratio = Crystal orientation in extrusion direction / (Crystal orientation in extrusion direction + Crystal orientation in vertical direction)
　結晶配向度は、Ｘ線回折により求めた。押出方向の結晶配向度は、ハニカム焼結体の押出面のＸ線回折を測定し、（００２）面の回折強度（＝Ｉ（００２））及び（２３０）面の回折強度（＝Ｉ（２３０））より、以下の式により算出した。 The degree of crystal orientation was determined by X-ray diffraction. The degree of crystal orientation in the extrusion direction is determined by measuring the X-ray diffraction of the extruded surface of the honeycomb sintered body, and the diffraction intensity of the (002) plane (= I (002)) and the diffraction intensity of the (230) plane (= I (230) )), The following formula was used.
　結晶配向度＝Ｉ（００２）／｛Ｉ（００２）＋Ｉ（２３０）｝ Crystal orientation degree = I (002) / {I (002) + I (230)}
　垂直方向の結晶配向度は、ハニカム焼結体の垂直面のＸ線回折を測定し、上記と同様にして、Ｉ（００２）及びＩ（２３０）を求めることにより算出した。 The crystal orientation degree in the vertical direction was calculated by measuring X-ray diffraction of the vertical surface of the honeycomb sintered body and obtaining I (002) and I (230) in the same manner as described above.
　なお、（００２）面の回折強度は、２θ＝５０．８°付近に現れるピークであり、（２３０）面の回折ピークは、２θ＝３３．７°付近に現れるピークである。 The diffraction intensity of the (002) plane is a peak appearing near 2θ = 50.8 °, and the diffraction peak of the (230) plane is a peak appearing near 2θ = 33.7 °.
　図６及び図７は、押出面のＸ線回折を測定するための測定サンプルの作製を示す斜視図である。 6 and 7 are perspective views showing the production of a measurement sample for measuring the X-ray diffraction of the extruded surface.
　図６に示すように、ハニカム焼結体１の端面１ａを含む領域４を切り取り、図７に示す測定サンプルを作製した。図７に示す測定サンプル５を用い、この測定サンプル５の押出面５ａのＸ線回折を測定した。 As shown in Fig. 6, the region 4 including the end face 1a of the honeycomb sintered body 1 was cut out to prepare a measurement sample shown in Fig. 7. Using the measurement sample 5 shown in FIG. 7, the X-ray diffraction of the extruded surface 5a of the measurement sample 5 was measured.
　図８及び図９は、垂直面、すなわち、押出面に垂直な方向の面のＸ線回折を測定するためのサンプルの作製を示す斜視図である。 8 and 9 are perspective views showing the production of a sample for measuring X-ray diffraction on a vertical plane, that is, a plane perpendicular to the extrusion plane.
　図８に示すように、ハニカム焼結体１の８×２セルに相当する領域６を、押出方向Ａに沿って切り出し、図９に示す測定サンプル７を得た。この測定サンプル７の押出方向Ａに沿う面（押出面）７ａのＸ線回折の測定を行った。 As shown in FIG. 8, a region 6 corresponding to 8 × 2 cells of the honeycomb sintered body 1 was cut out along the extrusion direction A to obtain a measurement sample 7 shown in FIG. The measurement of the X-ray diffraction of the surface (extruded surface) 7a along the extrusion direction A of the measurement sample 7 was performed.
　以上のようにして、ハニカム焼結体についての結晶配向比を算出し、結果を表１に示した。 The crystal orientation ratio of the honeycomb sintered body was calculated as described above, and the results are shown in Table 1.
　なお、（００２）面はＣ軸に垂直な面であり、（００２）面の強度が高いということは、Ｃ軸が配向していることを意味する。 Note that the (002) plane is a plane perpendicular to the C axis, and the high strength of the (002) plane means that the C axis is oriented.
　〔触媒担持用セラミックフィルタの製造〕
　得られたハニカム焼結体（セラミックフィルタ本体）を、アルミナゾル中に浸漬させた後引き上げ、１１０℃にて３時間乾燥した。その後、電気炉で５００℃にて１時間焼成し、ハニカム焼結体の表面にアルミナ塗膜を形成した。形成したアルミナ塗膜は、Ａｌ２Ｏ３換算で、ハニカム焼結体１００重量部に対し、１５重量部であった。従って、アルミナ塗膜量は、１５重量％であった。 [Manufacture of ceramic filter for catalyst support]
The obtained honeycomb sintered body (ceramic filter main body) was dipped in alumina sol, then pulled up and dried at 110 ° C. for 3 hours. Then, it baked at 500 degreeC with the electric furnace for 1 hour, and formed the alumina coating film on the surface of a honeycomb sintered compact. The formed alumina coating film was 15 parts by weight with respect to 100 parts by weight of the honeycomb sintered body in terms of Al 2 O 3 . Therefore, the alumina coating amount was 15% by weight.
　アルミナゾルは、アルミナ２５重量％、水溶性セルロース１０重量％、脱イオン水６５重量％のスラリーを１時間撹拌しアルミナゾルを作製した。なお、アルミナの平均粒子径は、０．１５μｍであった。以上のようにして得られた触媒担持用セラミックフィルタについて、上記と同様にして熱膨張係数を測定した。測定結果を表１に示す。 The alumina sol was prepared by stirring a slurry of 25% by weight of alumina, 10% by weight of water-soluble cellulose and 65% by weight of deionized water for 1 hour. The average particle size of alumina was 0.15 μm. The thermal expansion coefficient of the catalyst-supporting ceramic filter obtained as described above was measured in the same manner as described above. The measurement results are shown in Table 1.
　（実施例２）
　〔チタン酸アルミニウムの製造〕
　酸化チタン３５４．７ｇ、酸化アルミニウム４０５．０ｇ、水酸化マグネシウム２１．３ｇ、及び酸化ケイ素１９．０ｇを振動ミルにて粉砕しながら、２．０時間混合した。 (Example 2)
[Production of aluminum titanate]
354.7 g of titanium oxide, 405.0 g of aluminum oxide, 21.3 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
　以上のようにして得られた粉砕混合物５００ｇをルツボに充填し、電気炉にて１５００℃で４時間焼成した。 500 g of the pulverized mixture obtained as described above was charged in a crucible and baked at 1500 ° C. for 4 hours in an electric furnace.
　得られた生成物について、Ｘ線回折にて結晶相を同定した。また得られた生成物について、走査型電子顕微鏡（ＳＥＭ）にて形状を確認し、フロー式粒子像分析にてアスペクト比（＝個数平均長軸径／個数平均短軸径）を測定した。測定結果を表１に示す。 The crystal phase of the obtained product was identified by X-ray diffraction. Further, the shape of the obtained product was confirmed with a scanning electron microscope (SEM), and the aspect ratio (= number average major axis diameter / number average minor axis diameter) was measured by flow particle image analysis. The measurement results are shown in Table 1.
　〔ハニカム焼結体の製造及び評価〕
　上記実施例で得られたチタン酸アルミニウムを用いて、実施例１と同様にしてハニカム焼結体を製造し、得られたハニカム焼結体について実施例１と同様にして評価した。評価結果を表１に示す。 [Manufacture and evaluation of honeycomb sintered bodies]
Using the aluminum titanate obtained in the above example, a honeycomb sintered body was produced in the same manner as in Example 1, and the obtained honeycomb sintered body was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
　〔触媒担持用セラミックフィルタの製造〕
　得られたハニカム焼結体（セラミックフィルタ本体）の表面上に、実施例１と同様にしてアルミナ塗膜を形成し、触媒担持用セラミックフィルタを製造した。 [Manufacture of ceramic filter for catalyst support]
On the surface of the obtained honeycomb sintered body (ceramic filter body), an alumina coating film was formed in the same manner as in Example 1 to produce a catalyst-supporting ceramic filter.
　また、得られた触媒担持用セラミックフィルタについて、実施例１と同様にして熱膨張係数を測定し、測定結果を表１に示した。 Further, with respect to the obtained catalyst-supporting ceramic filter, the thermal expansion coefficient was measured in the same manner as in Example 1, and the measurement results are shown in Table 1.
　（比較例１）
　〔チタン酸アルミニウム及びハニカム焼結体の製造〕
　実施例１と同様にして得られたチタン酸アルミニウムを用いて、実施例１と同様にしてハニカム焼結体（セラミックフィルタ本体）を製造した。 (Comparative Example 1)
[Production of aluminum titanate and honeycomb sintered body]
A honeycomb sintered body (ceramic filter body) was manufactured in the same manner as in Example 1 by using aluminum titanate obtained in the same manner as in Example 1.
　〔触媒担持用セラミックフィルタの製造〕
　得られたハニカム焼結体（セラミックフィルタ本体）を、１０重量％のポリビニルアルコール水溶液中に浸漬させ、取り出した後、１１０℃にて３時間乾燥させて、プレコート処理を施した。プレコート処理としてのポリマー塗膜量が、ハニカム焼結体１００重量部に対し５重量部となるようにポリマー塗膜を形成した。従って、ポリマー塗膜量は５重量％である。プレコート処理を施したハニカム焼結体に対し、実施例１と同様にしてアルミナゾル中に浸漬してアルミナ塗膜を形成し、触媒担持用セラミックフィルタを製造した。得られた触媒担持用セラミックフィルタの熱膨張率係数を上記と同様に測定し、測定結果を表１に示した。 [Manufacture of ceramic filter for catalyst support]
The obtained honeycomb sintered body (ceramic filter main body) was immersed in a 10% by weight polyvinyl alcohol aqueous solution, taken out, dried at 110 ° C. for 3 hours, and precoated. The polymer coating film was formed so that the amount of the polymer coating film as the precoat treatment was 5 parts by weight with respect to 100 parts by weight of the honeycomb sintered body. Therefore, the polymer coating amount is 5% by weight. The honeycomb sintered body subjected to the pre-coating treatment was immersed in alumina sol in the same manner as in Example 1 to form an alumina coating, and a catalyst-supporting ceramic filter was produced. The coefficient of thermal expansion of the obtained catalyst-carrying ceramic filter was measured in the same manner as described above, and the measurement results are shown in Table 1.
　（比較例２）
　実施例２で得られたハニカム焼結体に対し、比較例１と同様にプレコート処理を施し、その後アルミナ塗膜を形成して触媒担持用セラミックフィルタを製造した。 (Comparative Example 2)
The honeycomb sintered body obtained in Example 2 was pre-coated in the same manner as in Comparative Example 1, and then an alumina coating film was formed to produce a catalyst-supporting ceramic filter.
　上記と同様にして、触媒担持用セラミックフィルタの熱膨張係数を測定し、測定結果を表１に示した。 In the same manner as described above, the thermal expansion coefficient of the ceramic filter for supporting the catalyst was measured, and the measurement results are shown in Table 1.
　（比較例３）
　〔チタン酸アルミニウムの製造〕
　酸化チタン３４０．１ｇ、酸化アルミニウム３８８．３ｇ、水酸化マグネシウム５２．６ｇ、及び酸化ケイ素１９．０ｇを振動ミルにて粉砕しながら、２．０時間混合した。 (Comparative Example 3)
[Production of aluminum titanate]
340.1 g of titanium oxide, 388.3 g of aluminum oxide, 52.6 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
　以上のようにして得られた粉砕混合物５００ｇをルツボに充填し、電気炉にて１５００℃で４時間焼成した。 500 g of the pulverized mixture obtained as described above was charged in a crucible and baked at 1500 ° C. for 4 hours in an electric furnace.
　得られた生成物について、Ｘ線回折にて結晶相を同定した。また得られた生成物について、走査型電子顕微鏡（ＳＥＭ）にて形状を確認し、フロー式粒子像分析にてアスペクト比（＝個数平均長軸径／個数平均短軸径）を測定した。測定結果を表１に示す。 The crystal phase of the obtained product was identified by X-ray diffraction. Further, the shape of the obtained product was confirmed with a scanning electron microscope (SEM), and the aspect ratio (= number average major axis diameter / number average minor axis diameter) was measured by flow particle image analysis. The measurement results are shown in Table 1.
　〔ハニカム焼結体の製造及び評価〕
　本比較例で得られたチタン酸アルミニウムを用いる以外は、上記実施例１と同様にしてハニカム焼結体を製造し、評価した。 [Manufacture and evaluation of honeycomb sintered bodies]
A honeycomb sintered body was manufactured and evaluated in the same manner as in Example 1 except that the aluminum titanate obtained in this comparative example was used.
　評価結果を表１に示す。 Evaluation results are shown in Table 1.
　〔触媒担持用セラミックフィルタの製造〕
　実施例１と同様にして、得られたハニカム焼結体の上に直接アルミナ塗膜を形成し、触媒担持用セラミックフィルタを製造した。 [Manufacture of ceramic filter for catalyst support]
In the same manner as in Example 1, an alumina coating film was directly formed on the obtained honeycomb sintered body to produce a catalyst-supporting ceramic filter.
　触媒担持用セラミックフィルタの熱膨張係数を測定し、測定結果を表１に示した。 The thermal expansion coefficient of the catalyst-supporting ceramic filter was measured, and the measurement results are shown in Table 1.
　（比較例４）
　比較例３と同様にしてハニカム焼結体を製造した。得られたハニカム焼結体に対し、比較例１と同様にしてプレコート処理を施した後、アルミナ塗膜を形成して触媒担持用セラミックフィルタを製造した。 (Comparative Example 4)
A honeycomb sintered body was manufactured in the same manner as in Comparative Example 3. The resulting honeycomb sintered body was pre-coated in the same manner as in Comparative Example 1, and then an alumina coating film was formed to produce a catalyst-supporting ceramic filter.
　触媒担持用セラミックフィルタの熱膨張係数を表１に示す。 Table 1 shows the coefficient of thermal expansion of the ceramic filter for catalyst support.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、本発明に従う実施例１及び実施例２の触媒担持用セラミックフィルタは、プレコート処理を施さずとも、触媒担持用セラミックフィルタとして好ましい熱膨張係数である０に近い熱膨張係数を示している。これは、アスペクト比が１．３以上である柱状のチタン酸アルミニウムを用いることにより、セラミックフィルタ本体の押出方向における熱膨張係数を低くすることができるため、チタン酸アルミニウムの微少亀裂（マイクロクラック）内にアルミナが入り込んでも、０に近い低い熱膨張係数を得ることができるためである。 As shown in Table 1, the catalyst-supporting ceramic filters of Examples 1 and 2 according to the present invention have a thermal expansion coefficient close to 0, which is a preferable thermal expansion coefficient as a catalyst-supporting ceramic filter, without performing pre-coating treatment. Is shown. This is because, by using columnar aluminum titanate having an aspect ratio of 1.3 or more, the thermal expansion coefficient in the extrusion direction of the ceramic filter body can be lowered, so that micro cracks of the aluminum titanate (microcracks) This is because even if alumina enters, a low thermal expansion coefficient close to 0 can be obtained.
　比較例３及び比較例４の比較から明らかなように、アスペクト比が１．３未満であるチタン酸アルミニウムを用いた場合には、プレコート処理をしなければ低い熱膨張係数が得られない。 As is clear from the comparison between Comparative Example 3 and Comparative Example 4, when aluminum titanate having an aspect ratio of less than 1.3 is used, a low thermal expansion coefficient cannot be obtained unless precoating is performed.
　従って、本発明によれば、生産効率に優れた触媒担持用セラミックフィルタとすることができる。 Therefore, according to the present invention, a catalyst-supporting ceramic filter having excellent production efficiency can be obtained.
　１…ハニカム焼結体（セラミックフィルタ本体）
　１ａ…ハニカム焼結体の端面
　２…ハニカム焼結体の中心部
　３…ハニカム焼結体から切り出した測定サンプル
　４…ハニカム焼結体の端面近傍の領域
　５…ハニカム焼結体の押出面をＸ線回折測定するためのサンプル
　５ａ…押出面
　６…ハニカム焼結体の８×２セルの領域
　７…ハニカム焼結体の垂直面をＸ線回折測定するためのサンプル
　７ａ…垂直面
　１０…押圧棒
　１１，１２…支持点 1 ... Honeycomb sintered body (ceramic filter body)
DESCRIPTION OF SYMBOLS 1a ... End face of honeycomb sintered body 2 ... Center part of honeycomb sintered body 3 ... Measurement sample cut out from honeycomb sintered body 4 ... Area near end face of honeycomb sintered body 5 ... Extruded surface of honeycomb sintered body X Sample for measuring line diffraction 5a ... extruded surface 6 ... 8 × 2 cell region of honeycomb sintered body 7 ... Sample for measuring X-ray diffraction of vertical surface of honeycomb sintered body 7a ... vertical surface 10 ... pressing bar 11,12 ... support point

Claims (4)

  1. 　表面に触媒を担持するための触媒担持用セラミックフィルタであって、
    　平均アスペクト比（＝個数平均長軸径／個数平均短軸径）が１．３以上であるチタン酸アルミニウムから形成されたセラミックフィルタ本体と、
    　前記セラミックフィルタ本体の比表面積を高めるため前記セラミックフィルタ本体の表面上に直接設けられる無機微粒子膜とを備えることを特徴とする触媒担持用セラミックフィルタ。     A catalyst-supporting ceramic filter for supporting a catalyst on a surface,
    A ceramic filter body formed of aluminum titanate having an average aspect ratio (= number average major axis diameter / number average minor axis diameter) of 1.3 or more;
    A ceramic filter for supporting a catalyst, comprising: an inorganic fine particle film provided directly on a surface of the ceramic filter body in order to increase a specific surface area of the ceramic filter body.
  2. 　前記無機微粒子膜がアルミナ膜であることを特徴とする請求項１に記載の触媒担持用セラミックフィルタ。 The catalyst-supporting ceramic filter according to claim 1, wherein the inorganic fine particle film is an alumina film.
  3. 　前記セラミックフィルタ本体の押出方向における３０～８００℃の間の熱膨張係数が０．５×１０－６／℃以下であり、前記押出方向に対するＣ軸の結晶配向比が０．７５以上であることを特徴とする請求項１または２に記載の触媒担持用セラミックフィルタ。 The thermal expansion coefficient between 30 and 800 ° C. in the extrusion direction of the ceramic filter body is 0.5 × 10 −6 / ° C. or less, and the crystal orientation ratio of the C axis with respect to the extrusion direction is 0.75 or more. The ceramic filter for supporting a catalyst according to claim 1 or 2.
  4. 　請求項１～３のいずれか１項に記載の触媒担持用セラミックフィルタを製造する方法であって、
    　前記チタン酸アルミニウムを含む原料を押出成形した後、焼成することにより前記セラミックフィルタ本体を作製する工程と、
    　前記セラミックフィルタ本体の表面上に無機微粒子膜を形成する工程とを備えることを特徴とする触媒担持用セラミックフィルタの製造方法。     A method for producing a ceramic filter for supporting a catalyst according to any one of claims 1 to 3,
    A step of producing the ceramic filter body by extruding and then firing the raw material containing the aluminum titanate;
    And a step of forming an inorganic fine particle film on the surface of the ceramic filter body. A method for producing a catalyst-supporting ceramic filter.
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Publication number Priority date Publication date Assignee Title
JP2010285294A (en) * 2009-06-09 2010-12-24 Otsuka Chem Co Ltd Columnar aluminum titanate and method for producing the same, and honeycomb structure
JP2010285295A (en) * 2009-06-09 2010-12-24 Otsuka Chem Co Ltd Columnar aluminum titanate and method for producing the same, and honeycomb structure
WO2012046577A1 (en) * 2010-10-04 2012-04-12 大塚化学株式会社 Exhaust gas purification filter, and method for producing same
WO2018061958A1 (en) * 2016-09-30 2018-04-05 住友理工株式会社 Printing plate development method and development device

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WO2014014059A1 (en) * 2012-07-20 2014-01-23 住友化学株式会社 Honeycomb filter

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JP2008043852A (en) * 2006-08-11 2008-02-28 Tokyo Yogyo Co Ltd Ceramics filter
JP2008272737A (en) * 2007-03-30 2008-11-13 Ibiden Co Ltd Honeycomb filter

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JP2008043852A (en) * 2006-08-11 2008-02-28 Tokyo Yogyo Co Ltd Ceramics filter
JP2008272737A (en) * 2007-03-30 2008-11-13 Ibiden Co Ltd Honeycomb filter

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010285294A (en) * 2009-06-09 2010-12-24 Otsuka Chem Co Ltd Columnar aluminum titanate and method for producing the same, and honeycomb structure
JP2010285295A (en) * 2009-06-09 2010-12-24 Otsuka Chem Co Ltd Columnar aluminum titanate and method for producing the same, and honeycomb structure
WO2012046577A1 (en) * 2010-10-04 2012-04-12 大塚化学株式会社 Exhaust gas purification filter, and method for producing same
WO2018061958A1 (en) * 2016-09-30 2018-04-05 住友理工株式会社 Printing plate development method and development device

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