WO2017022407A1 - 排ガス浄化フィルタ - Google Patents

排ガス浄化フィルタ Download PDF

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Publication number
WO2017022407A1
WO2017022407A1 PCT/JP2016/070240 JP2016070240W WO2017022407A1 WO 2017022407 A1 WO2017022407 A1 WO 2017022407A1 JP 2016070240 W JP2016070240 W JP 2016070240W WO 2017022407 A1 WO2017022407 A1 WO 2017022407A1
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WIPO (PCT)
Prior art keywords
exhaust gas
porous filter
heat
ceramic layer
gas purification
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
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PCT/JP2016/070240
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English (en)
French (fr)
Japanese (ja)
Inventor
恵里子 前田
悠登 丹羽
周作 山村
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Denso Corp
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Denso Corp
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Publication date
Application filed by Denso Corp filed Critical Denso Corp
Priority to CN201680044690.8A priority Critical patent/CN107847915A/zh
Priority to DE112016003478.4T priority patent/DE112016003478T5/de
Publication of WO2017022407A1 publication Critical patent/WO2017022407A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
    • F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors
    • 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
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • 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
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/50—Silver
    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/022—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
    • F01N3/0222—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous the structure being monolithic, e.g. honeycombs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/104—Silver
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/209—Other metals
    • B01D2255/2092—Aluminium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/40—Mixed oxides
    • B01D2255/407—Zr-Ce mixed oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/915—Catalyst supported on particulate filters
    • B01D2255/9155—Wall flow filters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/012—Diesel engines and lean burn gasoline engines
    • 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
    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B01J2235/30—Scanning electron microscopy; Transmission electron microscopy
    • 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
    • F01N2330/00—Structure of catalyst support or particle filter
    • F01N2330/06—Ceramic, e.g. monoliths
    • 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
    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
    • F01N2510/065—Surface coverings for exhaust purification, e.g. catalytic reaction for reducing soot ignition temperature

Definitions

  • the present invention relates to an exhaust gas purification filter having a porous filter capable of collecting particulate matter and an Ag-containing catalyst supported on the porous filter.
  • the particulate matter contained in the exhaust gas of a diesel engine or a gasoline engine is captured.
  • the present invention relates to an exhaust gas purification filter that collects and reduces.
  • particulate matter such as carbon fine particles is discharged from diesel engines and gasoline engines.
  • PM particulate matter
  • regulations on PM emissions have become increasingly strict, and PM discharged from gasoline engine vehicles as well as diesel engine vehicles has become an important issue.
  • an exhaust gas purification filter having a honeycomb structure porous filter made of cordierite or the like and a catalyst supported thereon is used.
  • the catalyst is used for combustion removal of PM collected by the exhaust gas purification filter.
  • Ag etc. are used, for example (refer patent document 1).
  • the conventional exhaust gas purifying filter on which the catalyst containing Ag is supported has a problem that the PM combustion performance is likely to deteriorate in a high temperature environment.
  • the present invention has been made based on such a background, and an object of the present invention is to provide an exhaust gas purification filter in which the degree of deterioration of combustion characteristics with respect to PM is reduced in a high temperature environment.
  • One embodiment of the present invention includes a porous filter capable of collecting particulate matter contained in exhaust gas discharged from an internal combustion engine, and an Ag-containing catalyst supported on the porous filter.
  • the porous filter is an exhaust gas purification filter having a heat-resistant ceramic layer that fills at least a surface opening at a grain boundary of ceramic crystal grains constituting the porous filter.
  • a heat-resistant ceramic layer is formed at least on the surface opening of the grain boundary of the ceramic crystal grains constituting the porous filter. That is, the surface opening that can be an entrance to the grain boundary is blocked by the heat-resistant ceramic layer. Therefore, Ag diffusion into the grain boundary can be physically blocked. Therefore, the diffusion of Ag into the grain boundary in a high temperature environment is suppressed, and a decrease in the Ag amount on the surface of the porous filter can be suppressed.
  • the degree of deterioration in combustion characteristics with respect to PM is reduced even in a high temperature environment. Further, heating is performed when the Ag-containing catalyst is supported on the porous filter, but since diffusion of Ag into the grain boundary at the time of heating can also be prevented, the combustion characteristics with respect to the initial PM after production are reduced. Can be improved.
  • FIG. 1 is a schematic diagram of an exhaust gas purification filter installed in an exhaust gas flow path of an internal combustion engine in Embodiment 1.
  • FIG. FIG. 2 is a perspective view of an exhaust gas purification filter in the first embodiment.
  • FIG. 3 is an enlarged cross-sectional view in the axial direction of the exhaust gas purification filter in the first embodiment.
  • FIG. 4 is an enlarged cross-sectional view of the partition wall of the porous filter in the first embodiment.
  • FIG. 6 is a diagram showing a scanning electron micrograph at a magnification of 10000 times on the surface of the porous filter before forming the heat-resistant ceramic layer in Embodiment 1; and (b) after forming the heat-resistant ceramic layer.
  • FIG. 7 is a diagram showing a scanning electron micrograph at a magnification of 20000 times on the surface of the porous filter before forming the heat-resistant ceramic layer in Embodiment 1, and (b) after forming the heat-resistant ceramic layer.
  • FIG. 8 is a diagram showing a change in Ag concentration on the surface of an example product and a comparative example product of an exhaust gas purification filter in Experimental Example 1.
  • FIG. 9 is a diagram showing a change in PM combustion rate between an example product of an exhaust gas purification filter and a comparative example product in Experimental Example 1.
  • FIG. 10 is an enlarged cross-sectional view in the vicinity of a grain boundary of ceramics as a comparative product of the exhaust gas purification filter in Experimental Example 1.
  • FIG. 11 is a diagram showing a reflected electron image of a scanning electron microscope of a comparative example product of an exhaust gas purification filter embedded in resin in Experimental Example 1, and (b) a comparative example product of an exhaust gas purification filter embedded in resin. The figure which shows EPMA mapping.
  • FIG. 12 is a diagram showing the relationship between the firing temperature of the heat-resistant ceramic layer and the change in Ag concentration on the surface of the exhaust gas purification filter in Experimental Example 2.
  • FIG. 13 is a diagram showing the relationship between the firing temperature of the heat-resistant ceramic layer and the change in the PM combustion rate of the exhaust gas purification filter in Experimental Example 2.
  • the exhaust gas purification filter 1 of the present embodiment is used to remove particulate matter (that is, particulate matter: PM) contained in the exhaust gas discharged from the internal combustion engine 5. It is installed in the exhaust gas pipe 51 serving as a flow path.
  • the exhaust gas purification filter 1 can be applied to, for example, a diesel engine or a gasoline engine.
  • the exhaust gas purification filter 1 includes a porous filter 2 capable of collecting PM.
  • a porous filter 2 capable of collecting PM.
  • the porous filter 2 a honeycomb structure can be used.
  • the porous filter 2 has, for example, a columnar shape, and includes partition walls 22 provided in a lattice shape and a large number of cells 23 surrounded by the partition walls 22 and extending in the axial direction X.
  • the shape of the porous filter may be a columnar shape as in the present embodiment, but may be a polygonal column such as a quadrangular column.
  • the partition wall 22 can be formed so that the shape of the cell 23 in the radial cross section of the porous filter 2 (that is, the cross section in the direction perpendicular to the axial direction X) is a square as in this embodiment.
  • the partition wall 22 may be formed so that the shape of the cell 23 in the radial cross section of the porous filter 2 is a polygon such as a triangle, a hexagon, an octagon, or the like. May be.
  • either one of the end portions 27 and 28 in the axial direction X is sealed with a plug portion 29.
  • the end portion 27 is closed by the plug portion 29.
  • the upstream end 27 of the inflow cell 231 and the downstream end 28 of the discharge cell 232 are open.
  • the formation pattern of the stopper part 29 is not limited to this embodiment shown by FIG.2 and FIG.3.
  • both the upstream end 27 and the downstream end 28 may partially have the cell 23 closed by the plug 29, and the upstream end 27 and the downstream end Both may be partially provided with the cells 23 that are not blocked by the plug portions 29.
  • the porous filter 2 is a porous body composed of ceramic crystal grains 21, and has pores 26 therein.
  • the ceramic cordierite, SiC, aluminum titanate, or the like can be used.
  • a grain boundary 211 having a clearance of nanometer order exists between the crystal grains 21, and the heat resistant ceramic layer 25 made of, for example, a sintered body of ⁇ -alumina particles is present at the grain boundary 211. Is formed.
  • the heat-resistant ceramic layer 25 only needs to be formed so as to fill at least the surface opening 212 of the grain boundary 211. As shown in FIG.
  • the surface opening 212 may be formed so as to be at least partially filled, and further formed so as to cover the surface of the porous filter 2. May be.
  • the surface opening 212 is a portion where the grain boundary 211 of the crystal grain 21 communicates with the pores 26 and the cells 23 in the porous filter 2, and the grain boundary 211 is a support surface of the Ag-containing catalyst 3 and the oxide particles 4. It can be said that it is a part that communicates with.
  • the partition wall 22 of the porous filter 2 carries an Ag-containing catalyst 3 for burning and removing PM.
  • the Ag-containing catalyst 3 for example, Ag, an Ag alloy, a catalyst in which Ag and / or an Ag alloy are arranged between a plurality of alumina sheets, and the like can be used.
  • the Ag-containing catalyst 3 in the present embodiment is made of Ag.
  • the Ag-containing catalyst 3 is supported on the porous filter 2 through oxide particles 4 such as ceria-zirconia particles 41 and alumina particles 42.
  • the Ag-containing catalyst 3 includes the surface of the partition wall 22 (specifically, the surface exposed in the cell 23 in the partition wall 22) and the inside of the partition wall 22 (specifically, the surface exposed to the pores 26 in the partition wall 22). It is carried on.
  • the Ag-containing catalyst 3 is supported on the partition wall 22 of the porous filter 2 through the oxide particles 4.
  • ceria-zirconia particles 41 and alumina particles 42 are present in the oxide particles 4 in the present embodiment. That is, the ceria-zirconia particles 41 and the alumina particles 42 on which the Ag-containing catalyst 3 is supported are supported on the partition walls 22 of the porous filter 2.
  • a cordierite raw material used as a raw material for a porous filter having a honeycomb structure was prepared.
  • the cordierite raw material contains silica, talc, kaolin, alumina, aluminum hydroxide and the like, and contains carbon as a burned-out material for increasing the porosity.
  • the raw material composition was adjusted so that the final composition after firing was SiO 2 : 47 to 55% by mass, Al 2 O 3 : 33 to 42% by mass, and MgO: 12 to 18% by mass. .
  • the porosity of the porous filter can be controlled by adjusting the amount of carbon.
  • the cordierite raw material is mixed with a solvent such as water, a thickener, a dispersant and the like to be adjusted to a clay.
  • a solvent such as water, a thickener, a dispersant and the like.
  • the clay-like cordierite raw material was extruded using a mold and then dried to obtain a honeycomb-shaped formed body.
  • a cordierite raw material for plug formation (hereinafter referred to as “plug formation material”) is prepared, and this raw material is dispersed in a solvent such as water or oil together with a thickener, a dispersant, etc. Adjusted.
  • This slurry is obtained by stirring using a mixer.
  • a masking tape was affixed to both end faces of the honeycomb-shaped formed body. Thereafter, the masking tape was partially removed so that adjacent cells in the honeycomb formed body opened alternately on both end faces. Thereby, the opening part was formed in the both end surfaces of the cell which should be plugged.
  • the removal of the masking tape can be performed by, for example, laser light irradiation.
  • both end surfaces of the honeycomb formed body were immersed in the plug portion forming material slurry. As a result, an appropriate amount of plug forming material was infiltrated into the cell to be plugged from the opening.
  • the porous filter 2 having a honeycomb structure in which the openings of the adjacent cells 23 were alternately closed by the plugs 29 was obtained.
  • the porous filter 2 has a cylindrical shape, and the thickness of the partition wall 22 can be appropriately changed within a range of, for example, 0.1 mm to 0.4 mm. Further, the porosity of the porous filter 2 can be appropriately changed within a range of 40% to 70%, for example.
  • the porous filter was immersed in alumina sol. As a result, the alumina sol is sucked into the porous filter. Thereafter, the porous filter was taken out from the alumina sol, and excess alumina sol was blown off by air blow. Next, the porous filter was dried at a temperature of 150 ° C. and then fired at 800 to 1200 ° C. for 1 to 5 hours in a firing furnace. As a result, as shown in FIG. 5, the heat-resistant ceramic layer 25 made of alumina was formed at the grain boundaries 211 of the cordierite crystal grains 21. As the alumina sol, alumina sol 520 manufactured by Nissan Chemical Industries, Ltd. was used.
  • This alumina sol has an average primary particle size of 10 to 20 nm, a pH of 3 to 5 and a crystal form of boehmite.
  • ceramic fine particles such as alumina sol whose average primary particle diameter is smaller than the clearance of the grain boundary 211 of the crystal grain 21, the heat resistant ceramic layer 25 that blocks the surface opening 212 of the grain boundary 211 is more reliably formed.
  • the average primary particle diameter means a particle diameter at a volume integrated value of 50% in a particle size distribution obtained by a laser diffraction / scattering method.
  • an Ag-containing catalyst that functions as a PM combustion catalyst is supported on the honeycomb structure.
  • an Ag-containing catalyst supported on oxide particles was prepared as follows. Specifically, ⁇ alumina and silver oxide were weighed so that the molar ratio of Al to Ag was 10: 1, and these were put in a sealed container for hydrothermal synthesis. Next, pure water was added to the sealed container so that the solid content in the sealed container was 5% by mass or less, and nitric acid was injected in the same molar amount as Al. Ceria-zirconia solid solution particles were added to the solution and mixed. After the contents in the sealed container were agitated, the sealed container was sealed in an air atmosphere and maintained at a temperature of 175 ° C. and 10 atm for 24 hours. As a result, a sol containing alumina particles carrying Ag was obtained. In this way, a catalyst sol was obtained.
  • the porous filter was immersed in the catalyst sol. Thereafter, the porous filter was taken out from the catalyst sol, and excess sol adhering to the porous filter was blown off by air blowing. Next, after drying the porous filter at a temperature of 150 ° C., the porous filter was fired at a temperature of 400 to 1000 ° C. for 1 to 5 hours. As a result, the Ag-containing catalyst 3 was supported on the porous filter 2 through the oxide particles 4 composed of the ceria-zirconia particles 41 and the alumina particles. In this way, the exhaust gas purification filter 1 shown in FIGS. 2 to 5 was obtained.
  • the heat-resistant ceramic layer 25 is formed at least on the surface opening 212 of the grain boundary 211 of the crystal grain 21 made of cordierite constituting the porous filter 2. . That is, the surface opening 212 that can be an entrance into the grain boundary 211 is closed by the heat-resistant ceramic layer 25. Therefore, since the diffusion of Ag into the grain boundary 211 is physically blocked, the diffusion of Ag into the grain boundary 211 in a high temperature environment is suppressed, and the degree of decrease in the Ag amount on the surface of the porous filter 2 becomes smaller.
  • the exhaust gas purification filter 1 has a reduced degree of deterioration of combustion characteristics with respect to PM even in a high temperature environment. Furthermore, since diffusion of Ag into the grain boundary 211 during heating when the Ag-containing catalyst 3 is supported can be prevented, the combustion characteristics with respect to the initial PM after production can be improved.
  • FIGS. 6 and 7 show scanning electron microscope (SEM) photographs of the surface of the porous filter before and after the formation of the heat-resistant ceramic layer. Specifically, the partition walls were exposed by cutting each porous filter in the axial direction X, and the surface of the partition walls was observed by SEM. As shown in FIGS. 6A and 7A, in the porous filter before the heat-resistant ceramic layer is formed, there is a clearance at the grain boundary of the crystal grains. On the other hand, as shown in FIGS. 6B and 7B, after the formation of the heat-resistant ceramic layer, the clearance of the grain boundary is filled with the heat-resistant ceramic layer, and the surface opening of the grain boundary is blocked. .
  • SEM scanning electron microscope
  • the heat-resistant ceramic layer 25 is preferably formed not only on the surface opening 212 but also inside the grain boundary 211 and / or on the surface of the porous filter 2 (see FIG. 5). ). In this case, the diffusion of Ag from the Ag-containing catalyst 3 into the grain boundary 211 can be further prevented. In this case, the heat-resistant ceramic layer 25 can be easily formed. That is, for example, by immersing the porous filter in a slurry containing a material for forming the heat-resistant ceramic layer, such as the above-mentioned alumina sol, and after air blowing, the surface openings 212 of the grain boundaries 211 are heated.
  • a material for forming the heat-resistant ceramic layer such as the above-mentioned alumina sol
  • a porous filter in which the heat-resistant ceramic layer 25 is formed on the inside and the surface of the porous filter 2 can be easily obtained.
  • the heat-resistant ceramic layer 25 may fill all of the inside of the grain boundary, but may have a region not filled with the heat-resistant ceramic layer inside the grain boundary.
  • the heat-resistant ceramic layer 25 can be formed using ceramic fine particles having an average particle diameter smaller than the width of the grain boundary 211 of the ceramic crystal grains 21 constituting the porous filter 2 such as the above-mentioned alumina sol. .
  • ceramic fine particles having an average particle diameter can enter the grain boundaries of the crystal grains.
  • the heat-resistant ceramic layer 25 can be formed in the grain boundary 211 or on the surface as described above.
  • the porous filter when the porous filter is immersed in a slurry or sol containing ceramic fine particles, not only the grain boundaries 211 of the crystal grains 21 of the porous filter 2 but also the micron order (for example, 0.2 ⁇ m) existing in the porous filter 2. Slurries and sols containing ceramic fine particles also enter the pores 26 of up to 500 ⁇ m). However, the slurry and sol in the pores 26 are easily removed by air blowing. Therefore, it is possible to prevent the pores 26 from being filled with the sintered body of ceramic fine particles. Furthermore, an increase in pressure loss is suppressed.
  • the heat-resistant ceramic layer 25 is preferably made of a sintered body of ceramic fine particles having an average primary particle diameter of 100 nm or less. In this case, when the heat-resistant ceramic layer 25 is formed, the ceramic fine particles can be more reliably intruded into the grain boundaries 211 of the ceramic crystal grains 21 constituting the porous filter 2.
  • the heat-resistant ceramic layer 25 is preferably made of a sintered body of ceramic fine particles having an average primary particle diameter of 50 nm or less, and more preferably made of a sintered body of ceramic fine particles having an average primary particle diameter of 30 nm or less. It is good.
  • the average primary particle size of the ceramic fine particles in the heat-resistant ceramic layer can be determined by analysis of SEM photographs using image analysis software (for example, WinROOF from Mitani Corporation).
  • the heat-resistant ceramic layer 25 made of ⁇ -alumina is formed.
  • the heat-resistant ceramic layer 25 with high density is formed, the diffusion of Ag into the grain boundaries 211 can be further suppressed.
  • the heat-resistant ceramic layer 25 is stable at the operating temperature of the exhaust gas purification filter 1 (for example, a temperature of 100 to 950 ° C.) or at a high temperature environment during manufacture (for example, a temperature of 300 to 1000 ° C.) It can be made of a ceramic material.
  • the heat-resistant ceramic layer 25 made of at least one selected from alumina, ceria, zirconia, titania, silica, yttria, lanthanum oxide, neodymium oxide, magnesia, iron oxide, and ceria-zirconia solid solution may be formed. it can.
  • the heat-resistant ceramic layer 25 is formed by at least one selected from ceria, zirconia, titania, silica, yttria, lanthanum oxide, neodymium oxide, magnesia, iron oxide, and ceria-zirconia solid solution.
  • Promoter performance can be demonstrated. Thereby, promotion of PM combustion by Ag containing catalyst 3 can be performed.
  • the heat-resistant ceramic layer 25 can be formed of alumina other than ⁇ -alumina (for example, ⁇ -alumina, ⁇ -alumina, ⁇ -alumina), but the viewpoint that the heat-resistant ceramic layer 25 having excellent denseness can be formed. Is preferably ⁇ -alumina.
  • the crystal structure of each alumina such as ⁇ -alumina, ⁇ -alumina, ⁇ -alumina, and ⁇ -alumina can be controlled by the heating temperature after being immersed in the alumina sol.
  • the heat-resistant ceramic layer 25 made of alumina having a desired crystal structure can be formed by adjusting the heating temperature to 600 to 1200 ° C. and the heating time to 1 to 5 hours.
  • the Ag-containing catalyst 3 is supported on the porous filter 2 through oxide particles 4 composed of ceria-zirconia particles 41 and alumina particles 42 (see FIG. 5).
  • the PM combustion activity can be further improved by the cocatalyst function for the Ag-containing catalyst 3 by the ceria-zirconia particles 41 and the effect of increasing the specific surface area by the alumina particles 42.
  • the PM combustion activity can be further improved from the viewpoint that aggregation of Ag can be suppressed.
  • the oxide particles 4 for supporting the Ag-containing catalyst 3 include ceria particles, zirconia particles, titania particles, silica particles, yttria particles, lanthanum oxide particles, neodymium oxide particles, in addition to the above-described alumina particles and ceria-zirconia particles.
  • magnesia particles, iron oxide particles, and the like can be used, and a plurality of these can be used in combination.
  • Example 1 This example is an example in which various analysis evaluations are performed on the exhaust gas purification filter (example product) manufactured in the first embodiment.
  • the example product has a honeycomb-structured porous filter 2 made of cordierite and an Ag-containing catalyst 3 made of Ag supported on the honeycomb filter (see FIGS. 2 to 5). At least the surface opening 212 of the grain boundary 211 of the cordierite crystal grains 21 constituting the porous filter 2 is filled with the heat-resistant ceramic layer 25 made of ⁇ -alumina. Further, in this experimental example, for comparison, an exhaust gas purification filter (comparative example product) in which a heat-resistant ceramic layer was not formed was also analyzed and evaluated.
  • This comparative example product is an exhaust gas purification filter obtained in the same manner as the example product except that the porous filter was produced without being immersed in alumina sol.
  • Experimental Example 1 and Experimental Example 2 described later the same reference numerals as those used in the first embodiment represent the same constituent elements as those in the first embodiment unless otherwise indicated.
  • each exhaust gas purification filter is installed in the piping of a gasoline engine, and maintained for 5 hours at a temperature of 850 ° C. while alternately changing the air-fuel ratio (ie, A / F ratio) 13 atmosphere and air atmosphere. It was done by doing. Then, the partition walls are exposed by cutting each exhaust gas purification filter before and after the engine durability test, and the element concentrations (at least Ag and Al element concentrations) at any 10 points on the partition surface are measured with an electron beam microanalyzer (EPMA). It was measured by analysis.
  • EPMA electron beam microanalyzer
  • EPMA-1720 manufactured by Shimadzu Corporation was used, and the concentration of each element was measured under analysis conditions of an applied voltage of 15 kV and a beam size of 1 ⁇ m.
  • evaluation was performed using the relative concentration of Ag with respect to the alumina concentration.
  • the relative concentration (%) of Ag is calculated by the following equation (1).
  • the change (%) in Ag concentration was calculated by the following equation (2).
  • Ag concentration change 100 ⁇ (relative Ag concentration after endurance test ⁇ relative Ag concentration before endurance test) / relative Ag concentration before endurance test (2)
  • the exhaust gas purification filter of the example product has almost no change in the Ag concentration on the surface after the durability test.
  • the heat-resistant ceramic layer 25 is formed in at least the surface opening 212 of the grain boundary 211 of the crystal grains 21 of the ceramic (specifically cordierite) constituting the porous filter 2 in the example product. (See FIG. 4 and FIG. 5). That is, the presence of the heat-resistant ceramic layer 25 at least in the surface opening 212 suppresses the diffusion of the Ag-containing catalyst 3 (specifically, Ag) carried on the surface of the porous filter 2 into the grain boundaries. As described above, the decrease in the Ag concentration on the surface is suppressed. As a result, as can be seen from FIG. 9, a decrease in the PM combustion rate is suppressed even after the durability test.
  • FIG. 10 is a figure which shows the area
  • mapping analysis by EPMA was performed on the cross section of the comparative product. Specifically, a sample in which the cross section of the comparative example product was filled with resin was prepared, and an SEM photograph (however, a reflected electron image) of this sample was obtained. Furthermore, EPMA mapping analysis was performed on the same area as this SEM photograph. The result is shown in FIG. In the SEM photograph shown in FIG. 11 (a), the light gray area of the area A indicates cordierite, the relatively dark gray area of the area B indicates the resin used for sample adjustment, and the black area of the area C Indicates the air phase. A white area present in the area A made of cordierite indicates Ag. In FIG. 11A, the main Ag existence region is surrounded by an ellipse.
  • FIG.11 (b) cordierite, resin, and an air phase are shown in black, and the presence area
  • the example product having the porous filter in which the surface opening of the grain boundary is blocked by the heat-resistant ceramic layer has a lower grain boundary of Ag than the comparative product in which the surface opening is not blocked. Diffusion into is suppressed. Therefore, in the exhaust gas purification filter of the example product, the degree of deterioration of the combustion characteristics with respect to PM in a high temperature environment becomes small.
  • Example 2 In this example, by changing the heating temperature at the time of forming the heat-resistant ceramic layer, the heat-resistant ceramic layer made of alumina having a different crystal structure is formed. The influence of the crystal structure of the heat-resistant ceramic layer on the effect of suppressing Ag diffusion. This is an example to consider.
  • a porous filter having a honeycomb structure made of cordierite in which the openings of adjacent cells were alternately closed was obtained in the same manner as in the first embodiment. Further, as in Embodiment 1, after the porous filter was immersed in alumina sol, the porous filter was taken out from the alumina sol, and excess alumina sol was blown off by air blow.
  • the porous filter was dried at a temperature of 150 ° C., it was fired in a firing furnace at 600 ° C., 800 ° C., or 1000 ° C. for 5 hours, respectively.
  • a heat-resistant ceramic layer made of alumina was formed at the grain boundary of the cordierite crystal grains.
  • the alumina sol the same one as used in the first embodiment was used.
  • an exhaust gas purification filter was obtained by supporting an Ag-containing catalyst that functions as a PM combustion catalyst.
  • the Ag concentration on the surface of the exhaust gas purification filter having a heat-resistant ceramic layer formed by firing alumina sol at a temperature of 1000 ° C. hardly changes after the durability test.
  • a heat-resistant ceramic layer made of dense ⁇ -alumina is formed by firing at a high temperature of 1000 ° C. That is, the dense heat-resistant ceramic layer sufficiently suppresses the diffusion of Ag into the grain boundaries.
  • FIG. 13 a decrease in the PM combustion rate is suppressed even after the durability test.
  • the exhaust gas purification filter having a heat-resistant ceramic layer formed by firing alumina sol at temperatures of 600 ° C. and 800 ° C. has a higher Ag concentration on the surface after the durability test than when firing at a temperature of 1000 ° C. Had fallen.
  • a heat-resistant ceramic layer mainly composed of ⁇ -alumina is formed when fired at a temperature of 600 ° C.
  • a heat-resistant ceramic layer mainly composed of ⁇ -alumina and / or ⁇ -alumina is formed when fired at a temperature of 800 ° C. This is because these aluminas are less dense than ⁇ -alumina.
  • the diffusion of Ag is suppressed as compared with the case where there is no heat-resistant ceramic layer (specifically, the above-mentioned comparative example product).
  • the effect of suppressing the diffusion of Ag is reduced.
  • the rate of decrease in the PM combustion rate after the endurance test is greater than when firing at a temperature of 1000 ° C. Therefore, the heat-resistant ceramic layer is preferably made of ⁇ -alumina.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Biomedical Technology (AREA)
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  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Catalysts (AREA)
  • Filtering Materials (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Processes For Solid Components From Exhaust (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
PCT/JP2016/070240 2015-07-31 2016-07-08 排ガス浄化フィルタ Ceased WO2017022407A1 (ja)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002054422A (ja) * 2000-08-08 2002-02-20 Ngk Insulators Ltd セラミック製フィルター及びその製造方法
JP2003334443A (ja) * 2002-05-15 2003-11-25 Toyota Motor Corp パティキュレート酸化材及び酸化触媒
JP2009178673A (ja) * 2008-01-31 2009-08-13 Toyota Central R&D Labs Inc 排ガス浄化装置
WO2010041741A1 (ja) * 2008-10-09 2010-04-15 本田技研工業株式会社 排ガス浄化装置
WO2010058834A1 (ja) * 2008-11-21 2010-05-27 日産自動車株式会社 粒子状物質浄化材料、粒子状物質浄化材料を用いた粒子状物質浄化用フィルタ触媒及び粒子状物質浄化用フィルタ触媒の再生方法
JP2011206636A (ja) * 2010-03-29 2011-10-20 Kyocera Corp ハニカム構造体およびこれを用いた排気ガス処理装置

Family Cites Families (4)

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Publication number Priority date Publication date Assignee Title
JPH09234367A (ja) * 1995-12-25 1997-09-09 Cataler Kogyo Kk ディーゼルエンジン排ガス浄化用触媒
CN1473073A (zh) * 2000-09-08 2004-02-04 日本碍子株式会社 催化剂及氧化铝负载载体的制造方法
CN101181681A (zh) * 2007-12-17 2008-05-21 中国铝业股份有限公司 沥青烟气净化用催化剂及其制备方法
CN104411930B (zh) * 2012-06-28 2017-05-10 三井金属矿业株式会社 柴油颗粒过滤器和废气净化装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002054422A (ja) * 2000-08-08 2002-02-20 Ngk Insulators Ltd セラミック製フィルター及びその製造方法
JP2003334443A (ja) * 2002-05-15 2003-11-25 Toyota Motor Corp パティキュレート酸化材及び酸化触媒
JP2009178673A (ja) * 2008-01-31 2009-08-13 Toyota Central R&D Labs Inc 排ガス浄化装置
WO2010041741A1 (ja) * 2008-10-09 2010-04-15 本田技研工業株式会社 排ガス浄化装置
WO2010058834A1 (ja) * 2008-11-21 2010-05-27 日産自動車株式会社 粒子状物質浄化材料、粒子状物質浄化材料を用いた粒子状物質浄化用フィルタ触媒及び粒子状物質浄化用フィルタ触媒の再生方法
JP2011206636A (ja) * 2010-03-29 2011-10-20 Kyocera Corp ハニカム構造体およびこれを用いた排気ガス処理装置

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