WO2020105666A1 - Honeycomb structured body - Google Patents

Honeycomb structured body

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Publication number
WO2020105666A1
WO2020105666A1 PCT/JP2019/045382 JP2019045382W WO2020105666A1 WO 2020105666 A1 WO2020105666 A1 WO 2020105666A1 JP 2019045382 W JP2019045382 W JP 2019045382W WO 2020105666 A1 WO2020105666 A1 WO 2020105666A1
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WO
WIPO (PCT)
Prior art keywords
honeycomb
partition wall
particles
honeycomb structure
exhaust gas
Prior art date
Application number
PCT/JP2019/045382
Other languages
French (fr)
Japanese (ja)
Inventor
広和 五十嵐
Original Assignee
イビデン株式会社
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Filing date
Publication date
Application filed by イビデン株式会社 filed Critical イビデン株式会社
Publication of WO2020105666A1 publication Critical patent/WO2020105666A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
    • B01J35/56—
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors

Definitions

  • the present invention relates to a honeycomb structure.
  • Exhaust gas emitted from an internal combustion engine such as an automobile contains harmful gases such as carbon monoxide (CO), nitrogen oxides (NOx) and hydrocarbons (HC).
  • An exhaust gas purifying catalyst that decomposes such harmful gases is also called a three-way catalyst, and a honeycomb-shaped monolith substrate made of cordierite or the like is washcoated with a slurry containing precious metal particles having catalytic activity to provide a catalyst layer. Things are common.
  • Patent Document 1 discloses an exhaust gas purifying catalyst in which a monolith base material contains ceria-zirconia composite oxide particles and ⁇ -phase alumina particles, and precious metal particles are carried on the monolith base material.
  • Patent Document 2 discloses a honeycomb structure containing inorganic particles and inorganic fibers and / or whiskers and having a surface roughness Rz of the outer surface of the honeycomb unit of 5 to 50 ⁇ m.
  • the present invention has been made to solve the above problems, and an object of the present invention is to provide a honeycomb structure having high exhaust gas permeation and diffusion properties into partition walls and sufficient exhaust gas purification performance.
  • the honeycomb structure of the present invention is a honeycomb structure made of a honeycomb fired body in which a plurality of through holes are arranged in parallel in the longitudinal direction with partition walls,
  • the honeycomb fired body is composed of ceria-zirconia composite oxide particles and alumina particles,
  • the partition walls have an arithmetic average roughness (Ra) according to ISO4287-1997 of 1 to 10 ⁇ m.
  • the inventors of the present invention permeate exhaust gas into partition walls depending on the surface state (surface roughness) of partition walls, which is the contact surface with exhaust gas, It was found that the degree of diffusion is greatly different and the surface roughness of the partition walls greatly affects the exhaust gas purification performance.
  • Patent Document 2 describes controlling the surface roughness Rz of the outer surface of the honeycomb unit, but this makes the bonding strength sufficient when bonding the honeycomb unit through the sealing material layer. Therefore, the surface roughness is only controlled. That is, the surface roughness is not controlled in consideration of the relationship between the permeability of the exhaust gas into the partition wall and the exhaust gas purification performance.
  • the exhaust gas since the arithmetic mean roughness (Ra) of the partition walls is controlled within a predetermined range, the exhaust gas has high penetration and diffusivity into the partition walls, and has sufficient exhaust gas purification performance.
  • the Ra of the partition wall is less than 1 ⁇ m, the exhaust gas hardly penetrates into the partition wall because the resistance on the partition wall surface is small, and the exhaust gas purification performance becomes insufficient.
  • Ra of the partition wall exceeds 10 ⁇ m, the permeability of the exhaust gas into the partition wall is not improved, but the resistance to the exhaust gas flow flowing through the through hole increases, so that the exhaust gas becomes difficult to flow into the through hole, and the exhaust gas Purification performance becomes insufficient.
  • the partition wall preferably has a thickness of 0.05 to 0.15 mm.
  • the thickness of the partition wall is 0.05 to 0.15 mm, the partition wall as a whole can easily contribute to the purification of the exhaust gas, so that the purification performance of the exhaust gas can be improved. If the thickness of the partition wall is less than 0.05 mm, the amount of the partition wall becomes too small, which may deteriorate the purification performance. If the thickness of the partition wall exceeds 0.15 mm, gas penetrates into the inside of the partition wall. It can be difficult.
  • the partition walls have a porosity of 50 to 70%.
  • the porosity of the partition wall is 50 to 70%, the effect of permeation and diffusion of exhaust gas into the partition wall can be sufficiently exerted, and the purification performance is improved.
  • the porosity of the partition wall is less than 50%, the exhaust gas may not easily permeate into the partition wall, and when the porosity of the partition wall exceeds 70%, the amount of catalyst in the partition wall becomes too small, which may deteriorate the purification performance. is there.
  • the hydraulic diameter of the through holes is preferably 0.7 to 1.5 mm.
  • the hydraulic diameter of the through hole is 0.7 to 1.5 mm, the effect of permeation and diffusion of exhaust gas into the partition wall can be sufficiently exerted, and the purification performance is improved.
  • the hydraulic diameter of the through hole is less than 0.7 mm, the permeability of the gas into the partition wall is not improved, but the resistance to the exhaust gas flow flowing through the through hole increases, so that the exhaust gas does not easily flow into the through hole, and the exhaust gas If the hydraulic diameter of the through holes exceeds 1.5 mm, the exhaust gas may not easily penetrate into the partition walls.
  • FIG. 1 is a perspective view schematically showing an example of the honeycomb structure of the present invention.
  • FIG. 1 is a perspective view schematically showing an example of the honeycomb structure of the present invention.
  • a honeycomb structure 10 in the honeycomb structure 10, a plurality of through holes 12 are arranged side by side in the longitudinal direction (indicated by a double-headed arrow L in FIG. 1) with partition walls 13 therebetween, and an outer peripheral wall 14 is provided at the outermost periphery.
  • the honeycomb fired body 11 is provided.
  • the honeycomb fired body 11 contains ceria-zirconia composite oxide particles (hereinafter also referred to as CZ particles) and alumina particles.
  • CZ particles ceria-zirconia composite oxide particles
  • the partition walls have an arithmetic average roughness (Ra) of 1 to 10 ⁇ m in accordance with ISO4287-1997.
  • Ra arithmetic average roughness
  • the evaluation curve is a roughness curve R
  • the cutoff ⁇ c 0.8 mm
  • the surface roughness of the partition wall is measured at five points and averaged to obtain the surface roughness of the partition wall.
  • the exhaust gas since the arithmetic mean roughness (Ra) of the partition walls is controlled within a predetermined range, the exhaust gas has high penetration and diffusivity into the partition walls, and has sufficient exhaust gas purification performance.
  • the Ra of the partition wall is less than 1 ⁇ m, the exhaust gas hardly penetrates into the partition wall because the resistance on the partition wall surface is small, and the exhaust gas purification performance becomes insufficient.
  • Ra of the partition wall exceeds 10 ⁇ m, the permeability of the exhaust gas into the partition wall is not improved, but the resistance to the exhaust gas flow flowing through the through hole increases, so that the exhaust gas becomes difficult to flow into the through hole, and the exhaust gas Purification performance becomes insufficient.
  • the partition walls have a uniform thickness.
  • the thickness of the partition wall is preferably 0.05 to 0.15 mm.
  • the partition wall as a whole can easily contribute to the purification of the exhaust gas, so that the purification performance of the exhaust gas can be improved.
  • the thickness of the partition wall is less than 0.05 mm, the amount of the partition wall becomes too small, which may deteriorate the purification performance. If the thickness of the partition wall exceeds 0.15 mm, gas penetrates into the inside of the partition wall. It can be difficult.
  • the porosity of the partition walls is preferably 50 to 70%.
  • the porosity of the partition wall is 50 to 70%, the effect of permeation and diffusion of exhaust gas into the partition wall can be sufficiently exerted, and the purification performance is improved.
  • the porosity of the partition wall is less than 50%, the exhaust gas may not easily permeate into the partition wall, and when the porosity of the partition wall exceeds 70%, the amount of catalyst in the partition wall becomes too small, which may deteriorate the purification performance. is there.
  • the porosity of the honeycomb fired body can be measured by the weight method described below.
  • a honeycomb fired body is cut into a size of 10 cells ⁇ 10 cells ⁇ 10 mm to obtain a measurement sample.
  • This measurement sample is ultrasonically cleaned using ion-exchanged water and acetone, and then dried at 100 ° C. in an oven.
  • the measurement sample of 10 cells ⁇ 10 cells ⁇ 10 mm includes the outermost through hole and a partition wall forming the through hole in a state where 10 through holes are arranged in the vertical direction and 10 in the horizontal direction, A sample cut out so that the length in the longitudinal direction is 10 mm.
  • the true density is measured according to JIS R 1620 (1995) using an Auto Pycnometer 1320 manufactured by Micromeritics.
  • the exhaust time is 40 minutes.
  • the actual weight of the measurement sample is measured with an electronic balance (HR202i manufactured by A & D).
  • the honeycomb fired body is an extruded body containing CZ particles and alumina particles. That is, the honeycomb structure of the present invention is constituted by a honeycomb fired body produced by firing a honeycomb formed body obtained by extrusion-molding a raw material paste containing CZ particles and alumina particles. It can be confirmed by X-ray diffraction (XRD) that the honeycomb structure has the above-mentioned components.
  • XRD X-ray diffraction
  • the honeycomb structure of the present invention may be provided with a single honeycomb fired body or may be provided with a plurality of honeycomb fired bodies.
  • the honeycomb structure of the present invention includes a plurality of honeycomb fired bodies, it is preferable that the plurality of honeycomb fired bodies be bonded by an adhesive layer.
  • the content ratio of CZ particles constituting the honeycomb fired body is preferably 25 to 75% by weight.
  • the oxygen storage capacity (OSC) of cerium can be increased.
  • the alumina particles forming the honeycomb fired body are preferably ⁇ -phase alumina particles.
  • the heat resistance is high, and therefore, a high exhaust gas purification performance can be exhibited even after supporting a noble metal and using it for a long time.
  • the content ratio of the alumina particles forming the honeycomb fired body is preferably 15 to 35% by weight.
  • Examples of the shape of the honeycomb structure of the present invention include a columnar shape, a prismatic shape, an elliptic cylinder, an elliptic cylinder, and a round chamfered prism (for example, a round chamfered triangular prism).
  • the shape of the through holes of the honeycomb fired body is not limited to the quadrangular prism, but may be a triangular prism, a hexagonal prism, or the like.
  • the through holes may have different shapes, but it is preferable that they have the same shape. That is, it is preferable that the through holes surrounded by the partition walls have the same size in the cross section perpendicular to the longitudinal direction of the honeycomb fired body.
  • the density of the through holes in the cross section perpendicular to the longitudinal direction of the honeycomb fired body is preferably 31 to 155 holes / cm 2 .
  • the hydraulic diameter of the through holes is preferably 0.7 to 1.5 mm.
  • the hydraulic diameter of the through hole is 0.7 to 1.5 mm, the effect of permeation and diffusion of exhaust gas into the partition wall can be sufficiently exerted, and the purification performance is improved.
  • the hydraulic diameter of the through hole is less than 0.7 mm, the permeability of the gas into the partition wall is not improved, but the resistance to the exhaust gas flow flowing through the through hole increases, so that the exhaust gas does not easily flow into the through hole, and the exhaust gas If the hydraulic diameter of the through holes exceeds 1.5 mm, the exhaust gas may not easily penetrate into the partition walls.
  • the hydraulic diameter of the cells of the through holes is obtained by dividing 4 times the cross-sectional area of the through hole in the vertical cross section by the outer peripheral length of the through hole in the cross section obtained by cutting the through hole in the cross section perpendicular to the longitudinal direction of the honeycomb structure. can get.
  • the honeycomb fired body may further contain an inorganic fiber or an inorganic binder.
  • Alumina fibers are preferred as the inorganic fibers.
  • the mechanical properties of the honeycomb structure can be improved.
  • Boehmite is preferable as the inorganic binder. This is because most of boehmite becomes ⁇ -alumina by the firing process.
  • the honeycomb fired body carry a noble metal.
  • the noble metal include platinum group metals such as platinum, palladium and rhodium.
  • the amount of the noble metal supported on the entire honeycomb fired body is preferably 0.1 to 15 g / L, more preferably 0.5 to 10 g / L.
  • the loaded amount of noble metal refers to the weight of noble metal per apparent volume of the honeycomb structure.
  • the apparent volume of the honeycomb structure is the volume including the volume of voids, and when the adhesive layer is included, the volume of the adhesive layer is included.
  • an outer peripheral coat layer may be formed on the outer peripheral surface of the honeycomb fired body.
  • the thickness of the outer peripheral coat layer is preferably 0.1 to 2.0 mm.
  • the honeycomb structure of the present invention is, for example, a honeycomb formed body in which a plurality of through holes are arranged in parallel in the longitudinal direction with partition walls by forming a raw material paste containing CZ particles, alumina particles, inorganic fibers and an inorganic binder.
  • a forming step for producing, a drying step for drying the honeycomb formed body formed by the forming step, and a firing step for producing a honeycomb fired body by firing the honeycomb formed body dried by the drying step, Can be manufactured by.
  • the raw material paste may further contain inorganic fibers, an inorganic binder, an organic binder, a pore-forming agent, a molding aid, a dispersion medium, and the like.
  • CZ particles are a material used as a promoter (oxygen storage material) of an exhaust gas purification catalyst.
  • the CZ particles are preferably those in which ceria and zirconia form a solid solution.
  • the CZ particles may further contain a rare earth element other than cerium.
  • rare earth elements scandium (Sc), yttrium (Y), lanthanum (La), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), Examples include ytterbium (Yb) and ruthenium (Lu).
  • the CZ particles preferably contain 30 wt% or more of ceria, more preferably 40 wt% or more, and preferably 90 wt% or less, and more preferably 80 wt% or less.
  • the CZ particles preferably contain zirconia in an amount of 60% by weight or less, more preferably 50% by weight or less. Since such CZ particles have a small heat capacity, the temperature of the honeycomb structure easily rises, and the warm-up performance can be improved.
  • the average particle size of the CZ particles is preferably 1 to 50 ⁇ m. Further, the average particle diameter of the CZ particles is more preferably 1 to 30 ⁇ m. When the average particle diameter of the CZ particles is 1 to 50 ⁇ m, the surface area becomes large when the honeycomb structure is formed, so that the oxygen storage capacity can be increased.
  • alumina particles The type of alumina particles is not particularly limited, but ⁇ -phase alumina particles (hereinafter, also referred to as ⁇ -alumina particles) are preferable.
  • ⁇ -alumina particles By using the ⁇ -phase alumina particles as a partitioning material for the CZ particles, it is possible to prevent the alumina particles from being sintered to each other due to heat during use, so that it is possible to maintain the catalytic function. Furthermore, heat resistance can be increased by making the alumina particles into the ⁇ phase.
  • the average particle diameter of the alumina particles is not particularly limited, but from the viewpoint of improving gas purification performance and warm-up performance, it is preferably 1 to 10 ⁇ m, more preferably 1 to 5 ⁇ m.
  • the average particle size and particle size distribution of CZ particles and alumina particles can be determined by a laser diffraction type particle size distribution measuring device (MASTERSIZER2000 manufactured by MALVERN).
  • the average particle diameter, particle size distribution, blending ratio, etc. of the raw materials contained in the raw material paste are determined by the following method. It is preferable to adjust by (a plurality may be combined). (1) When the average particle diameter of the CZ particles and the alumina particles is increased, the arithmetic average roughness (Ra) in the partition walls increases. Therefore, the surface roughness of the partition wall can be adjusted by adjusting the average particle diameter of the CZ particles and the alumina particles. (2) Adjust the particle size distribution of CZ particles and alumina particles.
  • the particle size distribution is a sharp distribution in which many particles are distributed in the vicinity of the average pore size, the arithmetic average roughness (Ra) in the partition wall becomes small.
  • the particle size distribution is a broad distribution with few particles distributed in the vicinity of the average pore diameter, the arithmetic mean roughness (Ra) in the partition wall becomes large. Therefore, even if particles having the same average particle diameter are used, if the particle size distribution is different, the surface roughness of the partition wall is different. (3) Change the mixing ratio of CZ particles and alumina particles.
  • the material forming the inorganic fiber is not particularly limited, and examples thereof include alumina, silica, silicon carbide, silica-alumina, glass, potassium titanate, aluminum borate, and the like, and two or more kinds may be used in combination. Of these, alumina fibers are preferred.
  • the aspect ratio of the inorganic fiber is preferably 5 to 300, more preferably 10 to 200, and further preferably 10 to 100.
  • the inorganic fibers have an aspect ratio of 5 or more.
  • Boehmite is preferable as the inorganic binder.
  • Boehmite is an alumina monohydrate having a composition of AlOOH and is well dispersed in a medium such as water. Therefore, boehmite is preferably used as the alumina binder. Further, by using boehmite, the water content in the raw material paste can be lowered and the formability can be improved.
  • the organic binder is not particularly limited, and examples thereof include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol, phenol resin, and epoxy resin, and two or more kinds may be used in combination.
  • the pore-forming agent is not particularly limited, and examples thereof include acrylic resin, coke, starch and the like.
  • the pore forming agent refers to an agent used for introducing pores into the honeycomb fired body when manufacturing the honeycomb fired body.
  • the molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid soap, polyalcohol, and the like, and two or more kinds may be used in combination.
  • the dispersion medium is not particularly limited, and examples thereof include water, organic solvents such as benzene, alcohols such as methanol, and the like, and two or more kinds may be used in combination.
  • CZ particles 25 to 75% by weight based on the total solid content remaining after the firing step in the raw materials
  • alumina 15 to 35% by weight
  • alumina fibers 5 to 15% by weight
  • alumina binder 5 to 20% by weight are preferable.
  • mixing and kneading may be carried out using a mixer, an attritor or the like, or kneading may be carried out using a kneader or the like.
  • the raw material paste containing CZ particles and alumina particles is extrusion-molded to obtain a honeycomb molded body in which a plurality of through holes are arranged in parallel in the longitudinal direction with partition walls.
  • the shape of the honeycomb formed body is not particularly limited, but a columnar shape is preferable. Further, the diameter in the case of a columnar shape is preferably 150 mm or less. Further, the honeycomb formed body may have a prismatic shape, and when the honeycomb molded body has a prismatic shape, it is preferably a quadrangular prismatic shape.
  • a drying step of drying the formed honeycomb body to obtain a dried honeycomb body is performed.
  • the honeycomb formed body is dried by using a dryer such as a microwave dryer, a hot air dryer, a dielectric dryer, a reduced pressure dryer, a vacuum dryer, and a freeze dryer to produce a honeycomb dried body.
  • the honeycomb fired body is manufactured by firing the honeycomb dried body dried in the drying step. It should be noted that this step can be referred to as a “degreasing / firing step” because degreasing and firing of the dried honeycomb body are performed, but for convenience, it is referred to as a “firing step”.
  • the temperature of the firing step is preferably 800 to 1300 ° C, more preferably 900 to 1200 ° C.
  • the time of the firing step is preferably 1 to 24 hours, and more preferably 3 to 18 hours.
  • the atmosphere of the firing step is not particularly limited, but the oxygen concentration is preferably 1 to 20%.
  • the honeycomb structure of the present invention can be manufactured.
  • the method for manufacturing a honeycomb structure of the present invention may further include a supporting step of supporting a precious metal on the honeycomb fired body, if necessary.
  • Examples of the method of supporting the noble metal on the honeycomb fired body include a method of immersing the honeycomb fired body or the honeycomb structure in a solution containing noble metal particles or a complex, and then lifting and heating.
  • the honeycomb structure includes an outer peripheral coat layer
  • a noble metal may be supported on the honeycomb fired body before forming the outer peripheral coat layer, or the precious metal may be added to the honeycomb fired body or the honeycomb structure after forming the outer peripheral coat layer. You may carry.
  • the loading amount of the noble metal loaded in the loading step is preferably 0.1 to 15 g / L, and more preferably 0.5 to 10 g / L.
  • the outer peripheral coat layer when the outer peripheral coat layer is formed on the outer peripheral surface of the honeycomb fired body, the outer peripheral coat layer applies the outer peripheral coat layer paste to the outer peripheral surface excluding both end faces of the honeycomb fired body. After that, it can be formed by drying and solidifying.
  • the peripheral coat layer paste may have the same composition as the raw material paste.
  • Example 1 CZ particles (average particle diameter: 2 ⁇ m, particle size distribution 62%) are 26.5% by weight, ⁇ -alumina particles (average particle diameter: 2 ⁇ m, particle size distribution 71%) are 13.2% by weight, alumina fibers (average fiber diameter). : 3 ⁇ m, average fiber length: 60 ⁇ m) 5.3% by weight, boehmite 11.3% by weight as an alumina binder, methylcellulose 7.8% by weight as an organic binder, and acrylic resin 1.9% by weight as a pore-forming agent.
  • the raw material paste was extrusion-molded using an extrusion molding machine to produce a columnar honeycomb molded body.
  • the honeycomb formed body was dried at an output of 1.8 A and a microwave irradiation time of 110 seconds.
  • the dried honeycomb body obtained was degreased and fired at 1100 ° C. for 10 hours to produce a honeycomb fired body according to Example 1.
  • the honeycomb fired body was a column having a diameter of 117 mm and a length of 80 mm, the density of through holes was 77.5 pieces / cm 2 (500 cpsi), the partition wall thickness was 0.127 mm (5 mil), and the porosity was 60. %, And the hydraulic diameter of the through hole was 1.01 mm.
  • Example 2 and 3 and Comparative Examples 1 and 2 A honeycomb structure was produced in the same manner as in Example 1 except that the average particle size and particle size distribution of CZ particles and the average particle size and particle size distribution of ⁇ -alumina particles were changed as shown in Table 1.
  • SJ-210 small surface roughness measuring device manufactured by Mitutoyo Corporation
  • the honeycomb structure of the present invention was excellent in purification performance because the arithmetic average roughness (Ra) in the partition walls was controlled to 1 to 10 ⁇ m.
  • honeycomb structure 11 honeycomb fired body 12 through hole 13 partition wall 14 outer peripheral wall

Abstract

Provided is a honeycomb structured body that allows greater penetration and dispersion of exhaust gas into a partition wall and has sufficient ability to purify exhaust gas. This honeycomb structured body comprises a honeycomb fired body in which multiple through holes are arranged side by side in the longitudinal direction and are separated by a partition wall, and is characterized in that the honeycomb fired body comprises ceria-zirconia composite oxide particles and alumina particles, and the partition wall has an arithmetic mean roughness (Ra) of 1-10 µm in accordance with ISO 4287-1997.

Description

ハニカム構造体Honeycomb structure
本発明は、ハニカム構造体に関する。 The present invention relates to a honeycomb structure.
自動車等の内燃機関から排出される排ガスには、一酸化炭素（ＣＯ）、窒素酸化物（ＮＯｘ）、炭化水素（ＨＣ）等の有害ガスが含まれている。そのような有害ガスを分解する排ガス浄化触媒は三元触媒とも称され、コージェライト等からなるハニカム状のモノリス基材に触媒活性を有する貴金属粒子を含むスラリーをウォッシュコートして触媒層を設けたものが一般的である。 Exhaust gas emitted from an internal combustion engine such as an automobile contains harmful gases such as carbon monoxide (CO), nitrogen oxides (NOx) and hydrocarbons (HC). An exhaust gas purifying catalyst that decomposes such harmful gases is also called a three-way catalyst, and a honeycomb-shaped monolith substrate made of cordierite or the like is washcoated with a slurry containing precious metal particles having catalytic activity to provide a catalyst layer. Things are common.
特許文献１には、モノリス基材がセリア－ジルコニア複合酸化物粒子とθ相のアルミナ粒子とを含み、上記モノリス基材に貴金属粒子が担持された排ガス浄化触媒が開示されている。 Patent Document 1 discloses an exhaust gas purifying catalyst in which a monolith base material contains ceria-zirconia composite oxide particles and θ-phase alumina particles, and precious metal particles are carried on the monolith base material.
特許文献２には、無機粒子と無機繊維及び／又はウィスカとを含有し、ハニカムユニットの外面の表面粗さＲｚが５～５０μｍであるハニカム構造体が開示されている。 Patent Document 2 discloses a honeycomb structure containing inorganic particles and inorganic fibers and / or whiskers and having a surface roughness Rz of the outer surface of the honeycomb unit of 5 to 50 μm.
特開２０１５－８５２４１号公報JP, 2005-85241, A 国際公開第２００７／０００８２５号International Publication No. 2007/000825
特許文献１に記載の排ガス浄化触媒では、排ガスの浄化性能が充分ではなく、その原因について本発明者らが検討したところ、隔壁中への排ガスの浸透、拡散性が不充分であることが排ガスの浄化性能が不充分になる原因であると推定した。 In the exhaust gas purifying catalyst described in Patent Document 1, the exhaust gas purifying performance is not sufficient, and the inventors of the present invention have investigated the cause of the exhaust gas purifying catalyst. It was estimated that this was the cause of insufficient purification performance.
本発明は、上記課題を解決するためになされた発明であり、隔壁中への排ガスの浸透、拡散性が高く、充分な排ガス浄化性能を有するハニカム構造体を提供することを目的とする。 The present invention has been made to solve the above problems, and an object of the present invention is to provide a honeycomb structure having high exhaust gas permeation and diffusion properties into partition walls and sufficient exhaust gas purification performance.
本発明のハニカム構造体は、複数の貫通孔が隔壁を隔てて長手方向に並設されたハニカム焼成体からなるハニカム構造体であって、
上記ハニカム焼成体は、セリア－ジルコニア複合酸化物粒子とアルミナ粒子とからなり、
上記隔壁におけるＩＳＯ４２８７－１９９７に準拠した算術平均粗さ（Ｒａ）が１～１０μｍであることを特徴とする。 The honeycomb structure of the present invention is a honeycomb structure made of a honeycomb fired body in which a plurality of through holes are arranged in parallel in the longitudinal direction with partition walls,
The honeycomb fired body is composed of ceria-zirconia composite oxide particles and alumina particles,
The partition walls have an arithmetic average roughness (Ra) according to ISO4287-1997 of 1 to 10 μm.
本発明者らは、セリア－ジルコニア複合酸化物粒子とアルミナ粒子とからなるハニカム構造体において、排ガスとの接触面である隔壁の表面状態（表面粗さ）によって、隔壁中への排ガスの浸透、拡散の度合いが大きく異なり、隔壁の表面粗さが排ガス浄化性能に大きく影響することを見出した。 In the honeycomb structure composed of ceria-zirconia composite oxide particles and alumina particles, the inventors of the present invention permeate exhaust gas into partition walls depending on the surface state (surface roughness) of partition walls, which is the contact surface with exhaust gas, It was found that the degree of diffusion is greatly different and the surface roughness of the partition walls greatly affects the exhaust gas purification performance.
なお、特許文献２にはハニカムユニットの外面の表面粗さＲｚを制御することが記載されているが、これはハニカムユニットをシール材層を介して接合する際の接合強度を充分なものにするために表面粗さを制御しているにすぎない。すなわち、隔壁に対する排ガスの浸透性や排ガス浄化性能との関係を考慮して表面粗さを制御したものではない。 Note that Patent Document 2 describes controlling the surface roughness Rz of the outer surface of the honeycomb unit, but this makes the bonding strength sufficient when bonding the honeycomb unit through the sealing material layer. Therefore, the surface roughness is only controlled. That is, the surface roughness is not controlled in consideration of the relationship between the permeability of the exhaust gas into the partition wall and the exhaust gas purification performance.
本発明のハニカム構造体では、隔壁における算術平均粗さ（Ｒａ）が所定の範囲に制御されているため、隔壁中への排ガスの浸透、拡散性が高く、充分な排ガス浄化性能を有する。
隔壁のＲａが１μｍ未満であると、隔壁表面での抵抗が小さいため排ガスが隔壁に浸透しにくく、排ガスの浄化性能が不充分となる。
一方、隔壁のＲａが１０μｍを超えると、排ガスの隔壁への浸透性が向上しない一方で貫通孔を流れる排ガス流に対する抵抗が大きくなるために排ガスが貫通孔に流入しにくくなってしまい、排ガスの浄化性能が不充分となる。 In the honeycomb structure of the present invention, since the arithmetic mean roughness (Ra) of the partition walls is controlled within a predetermined range, the exhaust gas has high penetration and diffusivity into the partition walls, and has sufficient exhaust gas purification performance.
When the Ra of the partition wall is less than 1 μm, the exhaust gas hardly penetrates into the partition wall because the resistance on the partition wall surface is small, and the exhaust gas purification performance becomes insufficient.
On the other hand, when Ra of the partition wall exceeds 10 μm, the permeability of the exhaust gas into the partition wall is not improved, but the resistance to the exhaust gas flow flowing through the through hole increases, so that the exhaust gas becomes difficult to flow into the through hole, and the exhaust gas Purification performance becomes insufficient.
本発明のハニカム構造体は、上記隔壁の厚さが０．０５～０．１５ｍｍであることが好ましい。
隔壁の厚さが０．０５～０．１５ｍｍであると、隔壁全体を排ガスの浄化に寄与させることができやすくなるため、排ガスの浄化性能を向上させることができる。隔壁の厚さが０．０５ｍｍ未満の場合は、隔壁の量が少なくなりすぎるため、浄化性能が低下することがあり、隔壁の厚さが０．１５ｍｍを超えると、隔壁内部までガスが浸透しにくくなることがある。 In the honeycomb structure of the present invention, the partition wall preferably has a thickness of 0.05 to 0.15 mm.
When the thickness of the partition wall is 0.05 to 0.15 mm, the partition wall as a whole can easily contribute to the purification of the exhaust gas, so that the purification performance of the exhaust gas can be improved. If the thickness of the partition wall is less than 0.05 mm, the amount of the partition wall becomes too small, which may deteriorate the purification performance. If the thickness of the partition wall exceeds 0.15 mm, gas penetrates into the inside of the partition wall. It can be difficult.
本発明のハニカム構造体は、上記隔壁の気孔率が５０～７０％であることが好ましい。
隔壁の気孔率が５０～７０％であると、隔壁中への排ガスの浸透、拡散性の効果を十分に発揮することができ、浄化性能が向上する。隔壁の気孔率が５０％未満では、隔壁中に排ガスが浸透しにくいことがあり、隔壁の気孔率が７０％を超えると、隔壁における触媒量が少なくなりすぎるため、浄化性能が低下することがある。 In the honeycomb structure of the present invention, it is preferable that the partition walls have a porosity of 50 to 70%.
When the porosity of the partition wall is 50 to 70%, the effect of permeation and diffusion of exhaust gas into the partition wall can be sufficiently exerted, and the purification performance is improved. When the porosity of the partition wall is less than 50%, the exhaust gas may not easily permeate into the partition wall, and when the porosity of the partition wall exceeds 70%, the amount of catalyst in the partition wall becomes too small, which may deteriorate the purification performance. is there.
本発明のハニカム構造体は、上記貫通孔の水力直径が０．７～１．５ｍｍであることが好ましい。
貫通孔の水力直径が０．７～１．５ｍｍであると、隔壁中への排ガスの浸透、拡散性の効果を十分に発揮することができ、浄化性能が向上する。貫通孔の水力直径が０．７ｍｍ未満では、ガスの隔壁への浸透性が向上しない一方で貫通孔を流れる排ガス流に対する抵抗が大きくなるために排ガスが貫通孔に流入しにくくなってしまい、排ガスの浄化性能が不充分となることがあり、貫通孔の水力直径が１．５ｍｍを超えると、隔壁中に排ガスが浸透しにくいことがある。 In the honeycomb structure of the present invention, the hydraulic diameter of the through holes is preferably 0.7 to 1.5 mm.
When the hydraulic diameter of the through hole is 0.7 to 1.5 mm, the effect of permeation and diffusion of exhaust gas into the partition wall can be sufficiently exerted, and the purification performance is improved. When the hydraulic diameter of the through hole is less than 0.7 mm, the permeability of the gas into the partition wall is not improved, but the resistance to the exhaust gas flow flowing through the through hole increases, so that the exhaust gas does not easily flow into the through hole, and the exhaust gas If the hydraulic diameter of the through holes exceeds 1.5 mm, the exhaust gas may not easily penetrate into the partition walls.
図１は、本発明のハニカム構造体の一例を模式的に示す斜視図である。FIG. 1 is a perspective view schematically showing an example of the honeycomb structure of the present invention.
（発明の詳細な説明）
［ハニカム構造体］
本発明のハニカム構造体について説明する。
図１は、本発明のハニカム構造体の一例を模式的に示す斜視図である。
図１に示すように、ハニカム構造体１０は、複数の貫通孔１２が隔壁１３を隔てて長手方向（図１中、両矢印Ｌで示す方向）に並設され、最外周に外周壁１４が設けられたハニカム焼成体１１からなる。
ハニカム焼成体１１は、セリア－ジルコニア複合酸化物粒子（以下、ＣＺ粒子ともいう）とアルミナ粒子を含んでなる。
図１に示すように、ハニカム構造体１０が単一のハニカム焼成体１１からなる場合、ハニカム焼成体１１はハニカム構造体そのものでもある。 (Detailed Description of the Invention)
[Honeycomb structure]
The honeycomb structure of the present invention will be described.
FIG. 1 is a perspective view schematically showing an example of the honeycomb structure of the present invention.
As shown in FIG. 1, in the honeycomb structure 10, a plurality of through holes 12 are arranged side by side in the longitudinal direction (indicated by a double-headed arrow L in FIG. 1) with partition walls 13 therebetween, and an outer peripheral wall 14 is provided at the outermost periphery. The honeycomb fired body 11 is provided.
The honeycomb fired body 11 contains ceria-zirconia composite oxide particles (hereinafter also referred to as CZ particles) and alumina particles.
As shown in FIG. 1, when the honeycomb structure 10 is composed of a single honeycomb fired body 11, the honeycomb fired body 11 is also the honeycomb structure itself.
本発明のハニカム構造体では、隔壁におけるＩＳＯ４２８７－１９９７に準拠した算術平均粗さ（Ｒａ）が１～１０μｍである。
隔壁の表面粗さは、例えば株式会社ミツトヨ製の小型表面粗さ測定器（ＳＪ－２１０（０．７５ｍＮタイプ）を使用し、評価曲線を粗さ曲線Ｒとし、カットオフλｃ＝０．８ｍｍ、λｓ＝２．５ｍｍ、測定速度０．５ｍｍ／ｓｅｃの条件で測定する。
隔壁において表面粗さを５点測定して、平均をとって隔壁の表面粗さとする。 In the honeycomb structure of the present invention, the partition walls have an arithmetic average roughness (Ra) of 1 to 10 μm in accordance with ISO4287-1997.
For the surface roughness of the partition wall, for example, a small surface roughness measuring instrument (SJ-210 (0.75 mN type) manufactured by Mitutoyo Corporation is used, the evaluation curve is a roughness curve R, and the cutoff λc = 0.8 mm, The measurement is performed under the conditions of λs = 2.5 mm and measurement speed of 0.5 mm / sec.
The surface roughness of the partition wall is measured at five points and averaged to obtain the surface roughness of the partition wall.
本発明のハニカム構造体では、隔壁における算術平均粗さ（Ｒａ）が所定の範囲に制御されているため、隔壁中への排ガスの浸透、拡散性が高く、充分な排ガス浄化性能を有する。
隔壁のＲａが１μｍ未満であると、隔壁表面での抵抗が小さいため排ガスが隔壁に浸透しにくく、排ガスの浄化性能が不充分となる。
一方、隔壁のＲａが１０μｍを超えると、排ガスの隔壁への浸透性が向上しない一方で貫通孔を流れる排ガス流に対する抵抗が大きくなるために排ガスが貫通孔に流入しにくくなってしまい、排ガスの浄化性能が不充分となる。 In the honeycomb structure of the present invention, since the arithmetic mean roughness (Ra) of the partition walls is controlled within a predetermined range, the exhaust gas has high penetration and diffusivity into the partition walls, and has sufficient exhaust gas purification performance.
When the Ra of the partition wall is less than 1 μm, the exhaust gas hardly penetrates into the partition wall because the resistance on the partition wall surface is small, and the exhaust gas purification performance becomes insufficient.
On the other hand, when Ra of the partition wall exceeds 10 μm, the permeability of the exhaust gas into the partition wall is not improved, but the resistance to the exhaust gas flow flowing through the through hole increases, so that the exhaust gas becomes difficult to flow into the through hole, and the exhaust gas Purification performance becomes insufficient.
本発明のハニカム構造体において、隔壁の厚さは、均一であることが好ましい。また、隔壁の厚さは、０．０５～０．１５ｍｍであることが好ましい。
隔壁の厚さが０．０５～０．１５ｍｍであると、隔壁全体を排ガスの浄化に寄与させることができやすくなるため、排ガスの浄化性能を向上させることができる。隔壁の厚さが０．０５ｍｍ未満の場合は、隔壁の量が少なくなりすぎるため、浄化性能が低下することがあり、隔壁の厚さが０．１５ｍｍを超えると、隔壁内部までガスが浸透しにくくなることがある。 In the honeycomb structure of the present invention, it is preferable that the partition walls have a uniform thickness. Further, the thickness of the partition wall is preferably 0.05 to 0.15 mm.
When the thickness of the partition wall is 0.05 to 0.15 mm, the partition wall as a whole can easily contribute to the purification of the exhaust gas, so that the purification performance of the exhaust gas can be improved. If the thickness of the partition wall is less than 0.05 mm, the amount of the partition wall becomes too small, which may deteriorate the purification performance. If the thickness of the partition wall exceeds 0.15 mm, gas penetrates into the inside of the partition wall. It can be difficult.
隔壁の気孔率は、５０～７０％であることが好ましい。
隔壁の気孔率が５０～７０％であると、隔壁中への排ガスの浸透、拡散性の効果を十分に発揮することができ、浄化性能が向上する。隔壁の気孔率が５０％未満では、隔壁中に排ガスが浸透しにくいことがあり、隔壁の気孔率が７０％を超えると、隔壁における触媒量が少なくなりすぎるため、浄化性能が低下することがある。 The porosity of the partition walls is preferably 50 to 70%.
When the porosity of the partition wall is 50 to 70%, the effect of permeation and diffusion of exhaust gas into the partition wall can be sufficiently exerted, and the purification performance is improved. When the porosity of the partition wall is less than 50%, the exhaust gas may not easily permeate into the partition wall, and when the porosity of the partition wall exceeds 70%, the amount of catalyst in the partition wall becomes too small, which may deteriorate the purification performance. is there.
ハニカム焼成体の気孔率は、以下に説明する重量法により測定することができる。
（１）ハニカム焼成体を１０セル×１０セル×１０ｍｍの大きさに切断して、測定試料とする。この測定試料をイオン交換水及びアセトンを用いて超音波洗浄した後、オーブンを用いて１００℃で乾燥する。なお、１０セル×１０セル×１０ｍｍの測定試料とは、貫通孔が縦方向に１０個、横方向に１０個並んだ状態で、最も外側の貫通孔とその貫通孔を構成する隔壁を含み、長手方向の長さが１０ｍｍとなるように切り出した試料を指す。
（２）測定顕微鏡（ニコン製Ｍｅａｓｕｒｉｎｇ　Ｍｉｃｒｏｓｃｏｐｅ　ＭＭ－４０　倍率：１００倍）を用いて、測定試料の断面形状の寸法を測定し、幾何学的な計算から体積を求める（なお、幾何学的な計算から体積を求めることができない場合は、飽水重量と水中重量とを実測して体積を測定する）。
（３）計算から求められた体積及びピクノメータで測定した測定試料の真密度から、測定試料が完全な緻密体であると仮定した場合の重量を計算する。なお、ピクノメータでの測定手順は（４）に示す通りとする。
（４）ハニカム焼成体を粉砕し、２３．６ｃｃの粉末を準備する。得られた粉末を２００℃で８時間乾燥させる。その後、Ｍｉｃｒｏｍｅｒｉｔｉｃｓ社製　Ａｕｔｏ　Ｐｙｃｎｏｍｅｔｅｒ１３２０を用いて、ＪＩＳ　Ｒ　１６２０（１９９５）に準拠して真密度を測定する。排気時間は４０分とする。
（５）測定試料の実際の重量を電子天秤（Ａ＆Ｄ製　ＨＲ２０２ｉ）で測定する。
（６）以下の式から、ハニカム焼成体の気孔率を求める。
（ハニカム焼成体の気孔率）＝１００－（測定試料の実際の重量／測定試料が完全な緻密体であると仮定した場合の重量）×１００［％］
なお、本発明のハニカム構造体に貴金属を直接担持させた場合であっても、貴金属担持によるハニカム焼成体の気孔率の変化は無視できるほど小さい。 The porosity of the honeycomb fired body can be measured by the weight method described below.
(1) A honeycomb fired body is cut into a size of 10 cells × 10 cells × 10 mm to obtain a measurement sample. This measurement sample is ultrasonically cleaned using ion-exchanged water and acetone, and then dried at 100 ° C. in an oven. In addition, the measurement sample of 10 cells × 10 cells × 10 mm includes the outermost through hole and a partition wall forming the through hole in a state where 10 through holes are arranged in the vertical direction and 10 in the horizontal direction, A sample cut out so that the length in the longitudinal direction is 10 mm.
(2) Using a measuring microscope (Measuring Microscope MM-40, made by Nikon, magnification: 100 times), measure the cross-sectional shape of the measurement sample, and obtain the volume from the geometrical calculation (the geometrical calculation If the volume cannot be calculated from the above, the volume is measured by measuring the saturated water weight and the underwater weight).
(3) From the volume obtained from the calculation and the true density of the measurement sample measured with a pycnometer, calculate the weight assuming that the measurement sample is a perfect dense body. The measurement procedure with the pycnometer is as shown in (4).
(4) The honeycomb fired body is crushed to prepare 23.6 cc of powder. The powder obtained is dried at 200 ° C. for 8 hours. Then, the true density is measured according to JIS R 1620 (1995) using an Auto Pycnometer 1320 manufactured by Micromeritics. The exhaust time is 40 minutes.
(5) The actual weight of the measurement sample is measured with an electronic balance (HR202i manufactured by A & D).
(6) The porosity of the honeycomb fired body is calculated from the following equation.
(Porosity of honeycomb fired body) = 100− (actual weight of measurement sample / weight when the measurement sample is assumed to be a completely dense body) × 100 [%]
Even when the precious metal is directly supported on the honeycomb structure of the present invention, the change in the porosity of the honeycomb fired body due to the precious metal carried is negligibly small.
本発明のハニカム構造体において、ハニカム焼成体は、ＣＺ粒子及びアルミナ粒子を含む押出成形体からなる。すなわち、本発明のハニカム構造体は、ＣＺ粒子及びアルミナ粒子を含む原料ペーストを押出成形して得られたハニカム成形体を焼成することにより作製されたハニカム焼成体により構成される。
ハニカム構造体が上記した成分を有していることは、Ｘ線回折（ＸＲＤ）にて確認することができる。 In the honeycomb structure of the present invention, the honeycomb fired body is an extruded body containing CZ particles and alumina particles. That is, the honeycomb structure of the present invention is constituted by a honeycomb fired body produced by firing a honeycomb formed body obtained by extrusion-molding a raw material paste containing CZ particles and alumina particles.
It can be confirmed by X-ray diffraction (XRD) that the honeycomb structure has the above-mentioned components.
本発明のハニカム構造体は、単一のハニカム焼成体を備えていてもよいし、複数個のハニカム焼成体を備えていてもよい。本発明のハニカム構造体が複数のハニカム焼成体を備える場合、複数個のハニカム焼成体が接着剤層により結合されていることが好ましい。 The honeycomb structure of the present invention may be provided with a single honeycomb fired body or may be provided with a plurality of honeycomb fired bodies. When the honeycomb structure of the present invention includes a plurality of honeycomb fired bodies, it is preferable that the plurality of honeycomb fired bodies be bonded by an adhesive layer.
本発明のハニカム構造体において、ハニカム焼成体を構成するＣＺ粒子の含有割合は、２５～７５重量％であることが好ましい。
ハニカム焼成体を構成するＣＺ粒子の含有割合が２５～７５重量％であると、セリウムの酸素吸蔵能（ＯＳＣ）を高めることができる。 In the honeycomb structure of the present invention, the content ratio of CZ particles constituting the honeycomb fired body is preferably 25 to 75% by weight.
When the content ratio of the CZ particles constituting the honeycomb fired body is 25 to 75% by weight, the oxygen storage capacity (OSC) of cerium can be increased.
本発明のハニカム構造体において、ハニカム焼成体を構成するアルミナ粒子は、θ相のアルミナ粒子であることが好ましい。
アルミナ粒子がθ相のアルミナ粒子であると耐熱性が高いため、貴金属を担持させ、長時間使用した後であっても高い排ガス浄化性能を発揮することができる。 In the honeycomb structure of the present invention, the alumina particles forming the honeycomb fired body are preferably θ-phase alumina particles.
When the alumina particles are θ-phase alumina particles, the heat resistance is high, and therefore, a high exhaust gas purification performance can be exhibited even after supporting a noble metal and using it for a long time.
本発明のハニカム構造体において、ハニカム焼成体を構成するアルミナ粒子の含有割合は、１５～３５重量％であることが好ましい。 In the honeycomb structure of the present invention, the content ratio of the alumina particles forming the honeycomb fired body is preferably 15 to 35% by weight.
本発明のハニカム構造体の形状としては、円柱状、角柱状、楕円柱状、長円柱状、丸面取りされている角柱状（例えば、丸面取りされている三角柱状）等が挙げられる。 Examples of the shape of the honeycomb structure of the present invention include a columnar shape, a prismatic shape, an elliptic cylinder, an elliptic cylinder, and a round chamfered prism (for example, a round chamfered triangular prism).
本発明のハニカム構造体において、ハニカム焼成体の貫通孔の形状としては、四角柱状に限定されず、三角柱状、六角柱状等が挙げられる。
貫通孔の形状はそれぞれ異なっていてもよいが、全て同じであることが好ましい。すなわち、ハニカム焼成体の長手方向に垂直な断面において、隔壁に囲まれた貫通孔のサイズが同じであることが好ましい。 In the honeycomb structure of the present invention, the shape of the through holes of the honeycomb fired body is not limited to the quadrangular prism, but may be a triangular prism, a hexagonal prism, or the like.
The through holes may have different shapes, but it is preferable that they have the same shape. That is, it is preferable that the through holes surrounded by the partition walls have the same size in the cross section perpendicular to the longitudinal direction of the honeycomb fired body.
本発明のハニカム構造体において、ハニカム焼成体の長手方向に垂直な断面の貫通孔の密度は、３１～１５５個／ｃｍ２であることが好ましい。 In the honeycomb structure of the present invention, the density of the through holes in the cross section perpendicular to the longitudinal direction of the honeycomb fired body is preferably 31 to 155 holes / cm 2 .
本発明のハニカム構造体においては、貫通孔の水力直径が０．７～１．５ｍｍであることが好ましい。
貫通孔の水力直径が０．７～１．５ｍｍであると、隔壁中への排ガスの浸透、拡散性の効果を十分に発揮することができ、浄化性能が向上する。貫通孔の水力直径が０．７ｍｍ未満では、ガスの隔壁への浸透性が向上しない一方で貫通孔を流れる排ガス流に対する抵抗が大きくなるために排ガスが貫通孔に流入しにくくなってしまい、排ガスの浄化性能が不充分となることがあり、貫通孔の水力直径が１．５ｍｍを超えると、隔壁中に排ガスが浸透しにくいことがある。
貫通孔のセルの水力直径は、貫通孔をハニカム構造体の長手方向と垂直な断面で切断した断面において、垂直な断面における貫通孔の断面積の４倍を貫通孔の外周長で割ることにより得られる。 In the honeycomb structure of the present invention, the hydraulic diameter of the through holes is preferably 0.7 to 1.5 mm.
When the hydraulic diameter of the through hole is 0.7 to 1.5 mm, the effect of permeation and diffusion of exhaust gas into the partition wall can be sufficiently exerted, and the purification performance is improved. When the hydraulic diameter of the through hole is less than 0.7 mm, the permeability of the gas into the partition wall is not improved, but the resistance to the exhaust gas flow flowing through the through hole increases, so that the exhaust gas does not easily flow into the through hole, and the exhaust gas If the hydraulic diameter of the through holes exceeds 1.5 mm, the exhaust gas may not easily penetrate into the partition walls.
The hydraulic diameter of the cells of the through holes is obtained by dividing 4 times the cross-sectional area of the through hole in the vertical cross section by the outer peripheral length of the through hole in the cross section obtained by cutting the through hole in the cross section perpendicular to the longitudinal direction of the honeycomb structure. can get.
本発明のハニカム構造体において、ハニカム焼成体にはさらに無機繊維や無機バインダが含まれていてもよい。 In the honeycomb structure of the present invention, the honeycomb fired body may further contain an inorganic fiber or an inorganic binder.
無機繊維としては、アルミナ繊維が好ましい。
無機繊維としてアルミナ繊維を用いると、ハニカム構造体の機械的特性を改善することができる。 Alumina fibers are preferred as the inorganic fibers.
When alumina fibers are used as the inorganic fibers, the mechanical properties of the honeycomb structure can be improved.
無機バインダとしては、ベーマイトが好ましい。
焼成工程によって、ベーマイトの大部分がγアルミナとなるからである。 Boehmite is preferable as the inorganic binder.
This is because most of boehmite becomes γ-alumina by the firing process.
本発明のハニカム構造体においては、ハニカム焼成体に貴金属が担持されていることが好ましい。
貴金属としては、例えば、白金、パラジウム、ロジウムなどの白金族金属が挙げられる。
ハニカム焼成体全体への貴金属の担持量は、０．１～１５ｇ／Ｌであることが好ましく、０．５～１０ｇ／Ｌであることがより好ましい。
本明細書において、貴金属の担持量とは、ハニカム構造体の見掛けの体積当たりの貴金属の重量をいう。なお、ハニカム構造体の見掛けの体積は、空隙の体積を含む体積であり、接着層を含む場合は接着層の体積を含むこととする。 In the honeycomb structure of the present invention, it is preferable that the honeycomb fired body carry a noble metal.
Examples of the noble metal include platinum group metals such as platinum, palladium and rhodium.
The amount of the noble metal supported on the entire honeycomb fired body is preferably 0.1 to 15 g / L, more preferably 0.5 to 10 g / L.
In the present specification, the loaded amount of noble metal refers to the weight of noble metal per apparent volume of the honeycomb structure. The apparent volume of the honeycomb structure is the volume including the volume of voids, and when the adhesive layer is included, the volume of the adhesive layer is included.
本発明のハニカム構造体において、ハニカム焼成体の外周面には、外周コート層が形成されていてもよい。
外周コート層の厚さは、０．１～２．０ｍｍであることが好ましい。 In the honeycomb structure of the present invention, an outer peripheral coat layer may be formed on the outer peripheral surface of the honeycomb fired body.
The thickness of the outer peripheral coat layer is preferably 0.1 to 2.0 mm.
［ハニカム構造体の製造方法］
次に、本発明のハニカム構造体を製造する方法について説明する。
本発明のハニカム構造体は、例えば、ＣＺ粒子、アルミナ粒子、無機繊維及び無機バインダを含む原料ペーストを成形することにより、複数の貫通孔が隔壁を隔てて長手方向に並設されたハニカム成形体を作製する成形工程と、上記成形工程により成形されたハニカム成形体を乾燥する乾燥工程と、上記乾燥工程により乾燥されたハニカム成形体を焼成することにより、ハニカム焼成体を作製する焼成工程と、により作製することができる。 [Manufacturing method of honeycomb structure]
Next, a method for manufacturing the honeycomb structure of the present invention will be described.
The honeycomb structure of the present invention is, for example, a honeycomb formed body in which a plurality of through holes are arranged in parallel in the longitudinal direction with partition walls by forming a raw material paste containing CZ particles, alumina particles, inorganic fibers and an inorganic binder. A forming step for producing, a drying step for drying the honeycomb formed body formed by the forming step, and a firing step for producing a honeycomb fired body by firing the honeycomb formed body dried by the drying step, Can be manufactured by.
（成形工程）
成形工程では、まず、ＣＺ粒子及びアルミナ粒子を混合して原料ペーストを調製する。
原料ペーストには、さらに無機繊維、無機バインダ、有機バインダ、造孔剤、成形助剤、分散媒等が含まれていてもよい。 (Molding process)
In the molding step, first, CZ particles and alumina particles are mixed to prepare a raw material paste.
The raw material paste may further contain inorganic fibers, an inorganic binder, an organic binder, a pore-forming agent, a molding aid, a dispersion medium, and the like.
ＣＺ粒子は、排ガス浄化触媒の助触媒（酸素貯蔵材）として用いられている材料である。ＣＺ粒子としては、セリアとジルコニアとが固溶体を形成したものが好ましい。 CZ particles are a material used as a promoter (oxygen storage material) of an exhaust gas purification catalyst. The CZ particles are preferably those in which ceria and zirconia form a solid solution.
ＣＺ粒子は、セリウム以外の希土類元素をさらに含んでいてもよい。希土類元素としては、スカンジウム（Ｓｃ）、イットリウム（Ｙ）、ランタン（Ｌａ）、プラセオジム（Ｐｒ）、ネオジム（Ｎｄ）、サマリウム（Ｓｍ）、ガドリニウム（Ｇｄ）、テルビウム（Ｔｂ）、ジスプロシウム（Ｄｙ）、イッテルビウム（Ｙｂ）、ルテニウム（Ｌｕ）等が挙げられる。 The CZ particles may further contain a rare earth element other than cerium. As rare earth elements, scandium (Sc), yttrium (Y), lanthanum (La), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), Examples include ytterbium (Yb) and ruthenium (Lu).
ＣＺ粒子は、セリアを３０重量％以上含むことが好ましく、４０重量％以上含むことがより好ましく、一方、セリアを９０重量％以下含むことが好ましく、８０重量％以下含むことがより好ましい。また、ＣＺ粒子は、ジルコニアを６０重量％以下含むことが好ましく、５０重量％以下含むことがより好ましい。このようなＣＺ粒子は熱容量が小さいため、ハニカム構造体の温度が上昇しやすくなり、暖機性能を高めることができる。 The CZ particles preferably contain 30 wt% or more of ceria, more preferably 40 wt% or more, and preferably 90 wt% or less, and more preferably 80 wt% or less. The CZ particles preferably contain zirconia in an amount of 60% by weight or less, more preferably 50% by weight or less. Since such CZ particles have a small heat capacity, the temperature of the honeycomb structure easily rises, and the warm-up performance can be improved.
ＣＺ粒子の平均粒子径は、１～５０μｍであることが好ましい。また、ＣＺ粒子の平均粒子径は１～３０μｍであることがより好ましい。ＣＺ粒子の平均粒子径が１～５０μｍであると、ハニカム構造体とした際に、表面積が大きくなるため、酸素吸蔵能を高くすることができる。 The average particle size of the CZ particles is preferably 1 to 50 μm. Further, the average particle diameter of the CZ particles is more preferably 1 to 30 μm. When the average particle diameter of the CZ particles is 1 to 50 μm, the surface area becomes large when the honeycomb structure is formed, so that the oxygen storage capacity can be increased.
アルミナ粒子の種類は特に限定されないが、θ相のアルミナ粒子（以下、θ－アルミナ粒子ともいう）であることが好ましい。
θ相のアルミナ粒子をＣＺ粒子の仕切り材として用いることにより、アルミナ粒子が使用中に熱によって互いに焼結することを抑制できるため、触媒機能を維持することが可能となる。さらに、アルミナ粒子をθ相とすることにより、耐熱性を高くすることができる。 The type of alumina particles is not particularly limited, but θ-phase alumina particles (hereinafter, also referred to as θ-alumina particles) are preferable.
By using the θ-phase alumina particles as a partitioning material for the CZ particles, it is possible to prevent the alumina particles from being sintered to each other due to heat during use, so that it is possible to maintain the catalytic function. Furthermore, heat resistance can be increased by making the alumina particles into the θ phase.
アルミナ粒子の平均粒子径は特に限定されないが、ガス浄化性能及び暖機性能を向上させる観点から、１～１０μｍであることが好ましく、１～５μｍであることがより好ましい。 The average particle diameter of the alumina particles is not particularly limited, but from the viewpoint of improving gas purification performance and warm-up performance, it is preferably 1 to 10 μm, more preferably 1 to 5 μm.
ＣＺ粒子及びアルミナ粒子の平均粒子径及び粒度分布は、レーザー回折式粒度分布測定装置（ＭＡＬＶＥＲＮ社製　ＭＡＳＴＥＲＳＩＺＥＲ２０００）により求めることができる。 The average particle size and particle size distribution of CZ particles and alumina particles can be determined by a laser diffraction type particle size distribution measuring device (MASTERSIZER2000 manufactured by MALVERN).
焼成工程後のハニカム構造体の隔壁における算術平均粗さ（Ｒａ）が１～１０μｍとなるようにするために、原料ペーストに含まれる原料の平均粒子径、粒度分布、配合割合等を下記の方法（複数を組み合わせてもよい）により調整することが好ましい。
（１）ＣＺ粒子及びアルミナ粒子の平均粒子径を大きくすると、隔壁における算術平均粗さ（Ｒａ）が大きくなる。そのため、ＣＺ粒子及びアルミナ粒子の平均粒子径を調整することで隔壁の表面粗さを調整することができる。
（２）ＣＺ粒子及びアルミナ粒子の粒度分布を調整する。粒度分布が、平均気孔径付近に多くの粒子が分布する、シャープな分布であると隔壁における算術平均粗さ（Ｒａ）が小さくなる。一方、粒度分布が、平均気孔径付近に分布する粒子が少なくブロードな分布であると隔壁における算術平均粗さ（Ｒａ）が大きくなる。
従って、平均粒子径が同じ粒子を使用しても粒度分布が異なれば隔壁の表面粗さは異なる。
（３）ＣＺ粒子及びアルミナ粒子の配合割合を変更する。ＣＺ粒子の平均粒子径及び粒度分布とアルミナ粒子の平均粒子径及び粒度分布が異なれば、ＣＺ粒子及びアルミナ粒子の配合割合を変更することで、表面粗さに与える各粒子の影響を合わせて変更することができるので、表面粗さを調整することができる。 In order to obtain the arithmetic average roughness (Ra) of the partition walls of the honeycomb structure after the firing step to be 1 to 10 μm, the average particle diameter, particle size distribution, blending ratio, etc. of the raw materials contained in the raw material paste are determined by the following method. It is preferable to adjust by (a plurality may be combined).
(1) When the average particle diameter of the CZ particles and the alumina particles is increased, the arithmetic average roughness (Ra) in the partition walls increases. Therefore, the surface roughness of the partition wall can be adjusted by adjusting the average particle diameter of the CZ particles and the alumina particles.
(2) Adjust the particle size distribution of CZ particles and alumina particles. If the particle size distribution is a sharp distribution in which many particles are distributed in the vicinity of the average pore size, the arithmetic average roughness (Ra) in the partition wall becomes small. On the other hand, if the particle size distribution is a broad distribution with few particles distributed in the vicinity of the average pore diameter, the arithmetic mean roughness (Ra) in the partition wall becomes large.
Therefore, even if particles having the same average particle diameter are used, if the particle size distribution is different, the surface roughness of the partition wall is different.
(3) Change the mixing ratio of CZ particles and alumina particles. If the average particle size and particle size distribution of CZ particles and the average particle size and particle size distribution of alumina particles are different, changing the compounding ratio of CZ particles and alumina particles also changes the effect of each particle on the surface roughness. Therefore, the surface roughness can be adjusted.
無機繊維を構成する材料としては、特に限定されないが、例えば、アルミナ、シリカ、炭化ケイ素、シリカアルミナ、ガラス、チタン酸カリウム、ホウ酸アルミニウム等が挙げられ、二種以上併用してもよい。これらの中では、アルミナ繊維が好ましい。 The material forming the inorganic fiber is not particularly limited, and examples thereof include alumina, silica, silicon carbide, silica-alumina, glass, potassium titanate, aluminum borate, and the like, and two or more kinds may be used in combination. Of these, alumina fibers are preferred.
無機繊維のアスペクト比は、５～３００であることが好ましく、１０～２００であることがより好ましく、１０～１００であることがさらに好ましい。
なお、無機繊維とは、アスペクト比が５以上のものをいう。 The aspect ratio of the inorganic fiber is preferably 5 to 300, more preferably 10 to 200, and further preferably 10 to 100.
The inorganic fibers have an aspect ratio of 5 or more.
無機バインダとしては、ベーマイトが好ましい。
ベーマイトは、ＡｌＯＯＨの組成で示されるアルミナ１水和物であり、水等の媒体に良好に分散するので、ベーマイトをアルミナバインダとして用いることが好ましい。
また、ベーマイトを用いることで原料ペースト中の水分率を低くし、成形性を高めることができる。 Boehmite is preferable as the inorganic binder.
Boehmite is an alumina monohydrate having a composition of AlOOH and is well dispersed in a medium such as water. Therefore, boehmite is preferably used as the alumina binder.
Further, by using boehmite, the water content in the raw material paste can be lowered and the formability can be improved.
有機バインダとしては、特に限定されないが、メチルセルロース、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ポリエチレングリコール、フェノール樹脂、エポキシ樹脂等が挙げられ、二種以上併用してもよい。 The organic binder is not particularly limited, and examples thereof include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol, phenol resin, and epoxy resin, and two or more kinds may be used in combination.
造孔剤としては、特に限定されないが、例えば、アクリル樹脂、コークス、デンプン等が挙げられる。
造孔剤とは、ハニカム焼成体を製造する際、ハニカム焼成体の内部に気孔を導入するために用いられるものをいう。 The pore-forming agent is not particularly limited, and examples thereof include acrylic resin, coke, starch and the like.
The pore forming agent refers to an agent used for introducing pores into the honeycomb fired body when manufacturing the honeycomb fired body.
成形助剤としては、特に限定されないが、エチレングリコール、デキストリン、脂肪酸、脂肪酸石鹸、ポリアルコール等が挙げられ、二種以上併用してもよい。 The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid soap, polyalcohol, and the like, and two or more kinds may be used in combination.
分散媒としては、特に限定されないが、水、ベンゼン等の有機溶媒、メタノール等のアルコール等が挙げられ、二種以上併用してもよい。 The dispersion medium is not particularly limited, and examples thereof include water, organic solvents such as benzene, alcohols such as methanol, and the like, and two or more kinds may be used in combination.
上記した原料としてＣＺ粒子、アルミナ粒子、アルミナ繊維及びアルミナバインダを使用した際、これらの配合割合は、原料中の焼成工程後に残存する全固形分に対し、ＣＺ粒子：２５～７５重量％、アルミナ粒子：１５～３５重量％、アルミナ繊維：５～１５重量％、アルミナバインダ：５～２０重量％が好ましい。 When CZ particles, alumina particles, alumina fibers and alumina binders are used as the above-mentioned raw materials, the mixing ratio of these is CZ particles: 25 to 75% by weight based on the total solid content remaining after the firing step in the raw materials, and alumina. Particles: 15 to 35% by weight, alumina fibers: 5 to 15% by weight, and alumina binder: 5 to 20% by weight are preferable.
原料ペーストを調製する際には、混合混練することが好ましく、ミキサー、アトライタ等を用いて混合してもよく、ニーダー等を用いて混練してもよい。 When preparing the raw material paste, it is preferable to carry out mixing and kneading, and mixing may be carried out using a mixer, an attritor or the like, or kneading may be carried out using a kneader or the like.
成形工程では、ＣＺ粒子とアルミナ粒子とを含む上記原料ペーストを押出成形することにより、複数の貫通孔が隔壁を隔てて長手方向に並設されたハニカム成形体を得る。 In the molding step, the raw material paste containing CZ particles and alumina particles is extrusion-molded to obtain a honeycomb molded body in which a plurality of through holes are arranged in parallel in the longitudinal direction with partition walls.
ハニカム成形体の形状は特に限定されるものではないが、円柱形状が好ましい。また、円柱形状の場合の直径が１５０ｍｍ以下であることが好ましい。
また、ハニカム成形体の形状は角柱形状であってもよく、角柱形状である場合は、四角柱形状であることが好ましい。 The shape of the honeycomb formed body is not particularly limited, but a columnar shape is preferable. Further, the diameter in the case of a columnar shape is preferably 150 mm or less.
Further, the honeycomb formed body may have a prismatic shape, and when the honeycomb molded body has a prismatic shape, it is preferably a quadrangular prismatic shape.
（乾燥工程）
続いて、ハニカム成形体を乾燥してハニカム乾燥体を得る乾燥工程を行う。
乾燥工程では、マイクロ波乾燥機、熱風乾燥機、誘電乾燥機、減圧乾燥機、真空乾燥機、凍結乾燥機等の乾燥機を用いて、ハニカム成形体を乾燥してハニカム乾燥体を作製する。 (Drying process)
Then, a drying step of drying the formed honeycomb body to obtain a dried honeycomb body is performed.
In the drying step, the honeycomb formed body is dried by using a dryer such as a microwave dryer, a hot air dryer, a dielectric dryer, a reduced pressure dryer, a vacuum dryer, and a freeze dryer to produce a honeycomb dried body.
（焼成工程）
焼成工程では、乾燥工程により乾燥されたハニカム乾燥体を焼成することにより、ハニカム焼成体を作製する。なお、この工程は、ハニカム乾燥体の脱脂及び焼成が行われるため、「脱脂・焼成工程」ということもできるが、便宜上「焼成工程」という。 (Firing process)
In the firing step, the honeycomb fired body is manufactured by firing the honeycomb dried body dried in the drying step. It should be noted that this step can be referred to as a “degreasing / firing step” because degreasing and firing of the dried honeycomb body are performed, but for convenience, it is referred to as a “firing step”.
焼成工程の温度は、８００～１３００℃であることが好ましく、９００～１２００℃であることがより好ましい。また、焼成工程の時間は、１～２４時間であることが好ましく、３～１８時間であることがより好ましい。焼成工程の雰囲気は特に限定されないが、酸素濃度が１～２０％であることが好ましい。 The temperature of the firing step is preferably 800 to 1300 ° C, more preferably 900 to 1200 ° C. Moreover, the time of the firing step is preferably 1 to 24 hours, and more preferably 3 to 18 hours. The atmosphere of the firing step is not particularly limited, but the oxygen concentration is preferably 1 to 20%.
以上の工程により、本発明のハニカム構造体を製造することができる。 Through the above steps, the honeycomb structure of the present invention can be manufactured.
（その他の工程）
本発明のハニカム構造体を製造する方法では、必要に応じて、上記ハニカム焼成体に貴金属を担持させる担持工程をさらに含んでいてもよい。
ハニカム焼成体に貴金属を担持する方法としては、例えば、貴金属粒子もしくは錯体を含む溶液にハニカム焼成体又はハニカム構造体を浸漬した後、引き上げて加熱する方法等が挙げられる。
ハニカム構造体が外周コート層を備える場合、外周コート層を形成する前のハニカム焼成体に貴金属を担持してもよいし、外周コート層を形成した後のハニカム焼成体又はハニカム構造体に貴金属を担持してもよい。 (Other processes)
The method for manufacturing a honeycomb structure of the present invention may further include a supporting step of supporting a precious metal on the honeycomb fired body, if necessary.
Examples of the method of supporting the noble metal on the honeycomb fired body include a method of immersing the honeycomb fired body or the honeycomb structure in a solution containing noble metal particles or a complex, and then lifting and heating.
When the honeycomb structure includes an outer peripheral coat layer, a noble metal may be supported on the honeycomb fired body before forming the outer peripheral coat layer, or the precious metal may be added to the honeycomb fired body or the honeycomb structure after forming the outer peripheral coat layer. You may carry.
本発明のハニカム構造体の製造方法において、上記担持工程で担持した貴金属の担持量は、０．１～１５ｇ／Ｌであることが好ましく、０．５～１０ｇ／Ｌであることがより好ましい。 In the method for manufacturing a honeycomb structure of the present invention, the loading amount of the noble metal loaded in the loading step is preferably 0.1 to 15 g / L, and more preferably 0.5 to 10 g / L.
本発明のハニカム構造体を製造する方法において、ハニカム焼成体の外周面に外周コート層を形成する場合、外周コート層は、ハニカム焼成体の両端面を除く外周面に外周コート層用ペーストを塗布した後、乾燥固化することにより形成することができる。外周コート層用ペーストとしては、原料ペーストと同じ組成のものが挙げられる。 In the method for manufacturing a honeycomb structure of the present invention, when the outer peripheral coat layer is formed on the outer peripheral surface of the honeycomb fired body, the outer peripheral coat layer applies the outer peripheral coat layer paste to the outer peripheral surface excluding both end faces of the honeycomb fired body. After that, it can be formed by drying and solidifying. The peripheral coat layer paste may have the same composition as the raw material paste.
（実施例）
以下、本発明をより具体的に開示した実施例を示す。なお、本発明は、以下の実施例のみに限定されるものではない。 (Example)
Hereinafter, examples will be described which more specifically disclose the present invention. The present invention is not limited to the following examples.
［ハニカム構造体の作製］
（実施例１）
ＣＺ粒子（平均粒子径：２μｍ、粒度分布６２％）を２６．５重量％、θ－アルミナ粒子（平均粒子径：２μｍ、粒度分布７１％）を１３．２重量％、アルミナ繊維（平均繊維径：３μｍ、平均繊維長：６０μｍ）を５．３重量％、アルミナバインダとしてベーマイトを１１．３重量％、有機バインダとしてメチルセルロースを７．８重量％、造孔剤としてアクリル樹脂を１．９重量％、同じく造孔剤としてグラファイトを２．３重量％、成形助剤として界面活性剤であるポリオキシエチレンオレイルエーテルを４．３重量％、及び、イオン交換水を２７．４重量％混合混練して、原料ペーストを調製した。
ＣＺ粒子及びアルミナ粒子の粒度分布は、平均粒子径±２０％に入る粒子の割合（％）として求めた。この値が大きいほど粒度分布がシャープであるといえる。 [Production of honeycomb structure]
(Example 1)
CZ particles (average particle diameter: 2 μm, particle size distribution 62%) are 26.5% by weight, θ-alumina particles (average particle diameter: 2 μm, particle size distribution 71%) are 13.2% by weight, alumina fibers (average fiber diameter). : 3 μm, average fiber length: 60 μm) 5.3% by weight, boehmite 11.3% by weight as an alumina binder, methylcellulose 7.8% by weight as an organic binder, and acrylic resin 1.9% by weight as a pore-forming agent. Similarly, 2.3% by weight of graphite as a pore-forming agent, 4.3% by weight of polyoxyethylene oleyl ether which is a surfactant as a molding aid, and 27.4% by weight of ion-exchanged water are mixed and kneaded. A raw material paste was prepared.
The particle size distribution of CZ particles and alumina particles was determined as the ratio (%) of particles that fall within the average particle diameter ± 20%. It can be said that the larger this value, the sharper the particle size distribution.
押出成形機を用いて、原料ペーストを押出成形して、円柱状のハニカム成形体を作製した。
マイクロ波乾燥機を用いて、ハニカム成形体を出力１．８Ａ、マイクロ波照射時間１１０秒で乾燥させた。 The raw material paste was extrusion-molded using an extrusion molding machine to produce a columnar honeycomb molded body.
Using a microwave dryer, the honeycomb formed body was dried at an output of 1.8 A and a microwave irradiation time of 110 seconds.
［焼成工程］
得られたハニカム成形体の乾燥体を１１００℃で１０時間脱脂・焼成することにより実施例１に係るハニカム焼成体を作製した。ハニカム焼成体は直径が１１７ｍｍ、長さが８０ｍｍの円柱状であり、貫通孔の密度が７７．５個／ｃｍ２（５００ｃｐｓｉ）、隔壁の厚さが０．１２７ｍｍ（５ｍｉｌ）、気孔率は６０％であり、貫通孔の水力直径は１．０１ｍｍであった。 [Firing process]
The dried honeycomb body obtained was degreased and fired at 1100 ° C. for 10 hours to produce a honeycomb fired body according to Example 1. The honeycomb fired body was a column having a diameter of 117 mm and a length of 80 mm, the density of through holes was 77.5 pieces / cm 2 (500 cpsi), the partition wall thickness was 0.127 mm (5 mil), and the porosity was 60. %, And the hydraulic diameter of the through hole was 1.01 mm.
（実施例２、３及び比較例１、２）
ＣＺ粒子の平均粒子径及び粒度分布、並びに、θ－アルミナ粒子の平均粒子径及び粒度分布を表１に示すように変更した他は実施例１と同様にしてハニカム構造体を作製した。 (Examples 2 and 3 and Comparative Examples 1 and 2)
A honeycomb structure was produced in the same manner as in Example 1 except that the average particle size and particle size distribution of CZ particles and the average particle size and particle size distribution of θ-alumina particles were changed as shown in Table 1.
［隔壁の表面粗さの測定］
各実施例及び各比較例に係るハニカム構造体をカットすることにより、隔壁を露出させ、株式会社ミツトヨ製の小型表面粗さ測定器（ＳＪ－２１０（０．７５ｍＮタイプ）を使用し、評価曲線を粗さ曲線Ｒとし、カットオフλｃ＝０．８ｍｍ、λｓ＝２．５ｍｍ、測定速度０．５ｍｍ／ｓｅｃの条件で表面粗さを５点測定して、平均をとって隔壁の表面粗さとした。 [Measurement of surface roughness of partition wall]
The partition walls are exposed by cutting the honeycomb structures according to each example and each comparative example, and a small surface roughness measuring device (SJ-210 (0.75 mN type) manufactured by Mitutoyo Corporation is used to evaluate the evaluation curve. Is defined as a roughness curve R, the surface roughness is measured at five points under the conditions of cutoff λc = 0.8 mm, λs = 2.5 mm, and a measurement speed of 0.5 mm / sec, and the average is taken as the surface roughness of the partition wall. did.
［浄化性能の測定］
各実施例及び各比較例に係るハニカム構造体からダイヤモンドカッターを用いて、断面が一辺２０ｍｍの正方形、長さ２５ｍｍの角柱状試験片を切り出した。この試験片を電気炉中で４５０℃で１０分間保持し加熱させた後に、４５０℃の模擬ガスを空間速度（ＳＶ）を１５００００／ｈｒで流しながら、触媒評価装置（堀場製作所製、ＭＥＸＡ－７００（Ｏ２、ＴＨＣ測定用）／ＭＥＸＡ－６０００ＦＴ（ＣＯ、ＮＯ、ＮＯ２測定用））を用いて、試験片から流出する各成分流出量を測定し、下記の式（１）
［（各成分の流入量－各成分の流出量）／（各成分の流入量）］×１００・・・（１）
で表される各成分の浄化率［％］を算出した。
なお、模擬ガスの構成成分は、一酸化窒素８００ｐｐｍ、酸素０．４０３３％、一酸化炭素６８００ｐｐｍ、ＴＨＣ（全炭化水素）１０６６ｐｐｍＣ、二酸化炭素７．３５％、水２．２０５％、窒素（ｂａｌａｎｃｅ）とした。
各実施例及び比較例で得られたハニカム構造体のＣＯ、ＴＨＣ、ＮＯ＋ＮＯ２の浄化率を表１に示す。 [Measurement of purification performance]
Using a diamond cutter, a square columnar test piece having a cross section of 20 mm on each side and a length of 25 mm was cut out from each of the honeycomb structures according to each example and each comparative example. After heating and heating this test piece at 450 ° C. for 10 minutes in an electric furnace, a catalyst evaluation device (MEXA-700, manufactured by Horiba, Ltd., while flowing a simulated gas at 450 ° C. at a space velocity (SV) of 150,000 / hr. (For measuring O 2 , THC) / MEXA-6000FT (for measuring CO, NO, NO 2 )), the amount of each component flowing out from the test piece was measured, and the following formula (1) was used.
[(Inflow amount of each component−outflow amount of each component) / (inflow amount of each component)] × 100 (1)
The purification rate [%] of each component represented by
In addition, the constituent components of the simulated gas are nitrogen monoxide 800 ppm, oxygen 0.4033%, carbon monoxide 6800 ppm, THC (total hydrocarbon) 1066 ppm C, carbon dioxide 7.35%, water 2.205%, nitrogen (balance). And
Table 1 shows the purification rates of CO, THC, and NO + NO 2 of the honeycomb structures obtained in the respective examples and comparative examples.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
表１に示すように、本発明のハニカム構造体は、隔壁における算術平均粗さ（Ｒａ）が１～１０μｍに制御されているので、浄化性能に優れていた。 As shown in Table 1, the honeycomb structure of the present invention was excellent in purification performance because the arithmetic average roughness (Ra) in the partition walls was controlled to 1 to 10 μm.
１０　　ハニカム構造体
１１　　ハニカム焼成体
１２　　貫通孔
１３　　隔壁
１４　　外周壁 10 honeycomb structure 11 honeycomb fired body 12 through hole 13 partition wall 14 outer peripheral wall

Claims (4)

  1. 複数の貫通孔が隔壁を隔てて長手方向に並設されたハニカム焼成体からなるハニカム構造体であって、
    前記ハニカム焼成体は、セリア－ジルコニア複合酸化物粒子とアルミナ粒子とからなり、
    前記隔壁におけるＩＳＯ４２８７－１９９７に準拠した算術平均粗さ（Ｒａ）が１～１０μｍであることを特徴とするハニカム構造体。     A honeycomb structure including a honeycomb fired body in which a plurality of through holes are arranged in parallel in a longitudinal direction with partition walls,
    The honeycomb fired body is composed of ceria-zirconia composite oxide particles and alumina particles,
    A honeycomb structure, wherein the partition walls have an arithmetic average roughness (Ra) according to ISO4287-1997 of 1 to 10 μm.
  2. 前記隔壁の厚さが０．０５～０．１５ｍｍである請求項１に記載のハニカム構造体。 The honeycomb structure according to claim 1, wherein the partition wall has a thickness of 0.05 to 0.15 mm.
  3. 前記隔壁の気孔率が５０～７０％である請求項１又は２に記載のハニカム構造体。 The honeycomb structure according to claim 1 or 2, wherein the partition walls have a porosity of 50 to 70%.
  4. 前記貫通孔の水力直径が０．７～１．５ｍｍである請求項１～３のいずれかに記載のハニカム構造体。 The honeycomb structure according to any one of claims 1 to 3, wherein the hydraulic diameter of the through hole is 0.7 to 1.5 mm.
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WO2001060514A1 (en) * 2000-02-21 2001-08-23 Ngk Insulators, Ltd. Ceramic honeycomb catalyst carrier and method for preparation thereof
JP2002326034A (en) * 2001-05-01 2002-11-12 Ngk Insulators Ltd Porous honeycomb structure and method of producing the same
WO2003074848A1 (en) * 2002-03-04 2003-09-12 Ibiden Co., Ltd. Honeycomb filter for exhaust gas decontamination and exhaust gas decontamination apparatus
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JP2010047456A (en) * 2008-08-22 2010-03-04 Sumitomo Chemical Co Ltd Method of manufacturing chlorine and catalyst
JP2010207708A (en) * 2009-03-10 2010-09-24 Ngk Insulators Ltd Honeycomb structure
WO2018012565A1 (en) * 2016-07-14 2018-01-18 イビデン株式会社 Honeycomb structure and production method for said honeycomb structure
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03284328A (en) * 1990-03-30 1991-12-16 Ngk Insulators Ltd Ceramic membraneous filter and production thereof
WO2001060514A1 (en) * 2000-02-21 2001-08-23 Ngk Insulators, Ltd. Ceramic honeycomb catalyst carrier and method for preparation thereof
JP2002326034A (en) * 2001-05-01 2002-11-12 Ngk Insulators Ltd Porous honeycomb structure and method of producing the same
WO2003074848A1 (en) * 2002-03-04 2003-09-12 Ibiden Co., Ltd. Honeycomb filter for exhaust gas decontamination and exhaust gas decontamination apparatus
JP2004299966A (en) * 2003-03-31 2004-10-28 Ngk Insulators Ltd Substrate for honeycomb filter and its manufacturing process, as well as honeycomb filter
JP2010047456A (en) * 2008-08-22 2010-03-04 Sumitomo Chemical Co Ltd Method of manufacturing chlorine and catalyst
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