WO2020031792A1 - 排ガス浄化触媒の製造方法 - Google Patents

排ガス浄化触媒の製造方法 Download PDF

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WO2020031792A1
WO2020031792A1 PCT/JP2019/029870 JP2019029870W WO2020031792A1 WO 2020031792 A1 WO2020031792 A1 WO 2020031792A1 JP 2019029870 W JP2019029870 W JP 2019029870W WO 2020031792 A1 WO2020031792 A1 WO 2020031792A1
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Prior art keywords
catalyst
exhaust gas
introduction
catalyst slurry
slurry
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PCT/JP2019/029870
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English (en)
French (fr)
Japanese (ja)
Inventor
万陽 城取
大司 望月
豪人 高山
禎憲 高橋
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エヌ・イーケムキャット株式会社
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Priority to CN201980036704.5A priority Critical patent/CN112203764B/zh
Publication of WO2020031792A1 publication Critical patent/WO2020031792A1/ja

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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
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • 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
    • 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, e.g. catalysed diesel particulate filters
    • 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 method for producing an exhaust gas purifying catalyst.
  • the exhaust gas discharged from the internal combustion engine contains particulate matter (PM) mainly composed of carbon, ash composed of non-combustible components, etc., and is known to cause air pollution.
  • PM particulate matter
  • the emission of particulate matter has been strictly regulated in diesel engines, which emit relatively more particulate matter than gasoline engines.
  • the regulation of particulate matter emissions has also been regulated in gasoline engines. It is being strengthened.
  • the properties such as viscosity and solid content of the slurry are adjusted, and one of the introduction-side cell and the discharge-side cell is pressurized to form
  • a method of adjusting the permeation of the catalyst slurry into the partition walls by causing a pressure difference between the fuel cell and the discharge side cell is known (for example, see Patent Document 1).
  • a high shear rate region By adjusting the viscosity of the low shear rate region and the viscosity, the coating time of the catalyst slurry can be shortened, and the method of suppressing blockage of the flow-through type cell (Patent Document 2), or by using a thixotropic slurry, A method for increasing a contact area between a catalyst formed on a cell surface and exhaust gas is known (Patent Document 3).
  • Patent Literature 1 has a wall flow type structure from the viewpoint of removing particulate matter, and is configured so that exhaust gas passes through pores of partition walls.
  • Patent Documents 2 and 3 relate to a technique of forming a catalyst layer on a partition wall of a flow-through type base material, and the present invention discloses a method of coating a catalyst layer on a pore surface inside a partition wall of a wall flow type base material. Has no relevance.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide a production method capable of stably obtaining an exhaust gas purifying catalyst having improved soot trapping performance with good reproducibility, and an object of the invention.
  • an object of the invention is to provide a production method capable of stably obtaining an exhaust gas purifying catalyst having improved soot trapping performance with good reproducibility, and an object of the invention.
  • the present invention is not limited to the object described above, and is an operation and effect derived from each configuration shown in the embodiment for carrying out the invention described later, and also has an operation and effect that cannot be obtained by the conventional technology. It can be positioned for other purposes.
  • the present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, it has been found that the soot collection performance of the exhaust gas purifying catalyst is also reduced by pore segregation or uneven coating due to segregation or uneven distribution of the catalyst layer when the catalyst layer is formed. Further, through a specific manufacturing process using a thixotropic slurry, the porosity is maintained at a relatively high level and the pore diameter is compared while suppressing the occurrence of such pore clogging and coating unevenness. The present inventors have found that the soot collection performance of the obtained exhaust gas purifying catalyst can be improved, and have completed the present invention. That is, the present invention provides various specific embodiments described below.
  • a method for producing an exhaust gas purifying catalyst for purifying exhaust gas discharged from a gasoline engine An introduction-side cell in which the end on the exhaust gas introduction side is open, and a discharge-side cell in which the end on the exhaust gas discharge side is open adjacent to the introduction-side cell, a wall flow type substrate defined by a porous partition wall.
  • the step of preparing An impregnation step of impregnating the end of the wall flow type substrate on the exhaust gas introduction side or the exhaust gas discharge side with a thixotropic catalyst slurry, By introducing a gas into the wall flow type base material from the end side impregnated with the catalyst slurry, the catalyst slurry impregnated in the wall flow type base material is applied to the pore surfaces of the partition walls. Coating process, A stopping step of stopping the introduction of the gas, The coated catalyst slurry is calcined, and the amount of coating of the catalyst layer (the amount of coating of the catalyst layer excluding the weight of the catalyst metal per 1 L of the wall flow type substrate) is 20 to 110 g / L.
  • the catalyst slurry has a TI value of 10 to 100, A method for producing an exhaust gas purifying catalyst.
  • the catalyst slurry contains at least one selected from the group consisting of methylamine, dimethylamine, trimethylamine, barium hydroxide, ammonium carbonate, ammonium hydrogen carbonate, and aqueous ammonia, The method for producing an exhaust gas purifying catalyst according to [1].
  • the catalyst slurry has a pH of 3 to 10, The method for producing an exhaust gas purifying catalyst according to [1] or [2].
  • An exhaust gas purifying catalyst for purifying exhaust gas discharged from a gasoline engine The introduction-side cell whose end on the exhaust gas introduction side is open, and the discharge-side cell whose end on the exhaust gas discharge side is open adjacent to the introduction-side cell, a wall flow type substrate defined by a porous partition wall, , And a catalyst layer formed in the pores of the partition wall, An impregnation step in which the catalyst layer impregnates the end of the wall flow type substrate on the exhaust gas introduction side or the exhaust gas discharge side with a thixotropic catalyst slurry; By introducing a gas into the, the application step of applying the catalyst slurry impregnated in the wall flow type substrate to the pore surface of the partition wall, and a stop step of stopping the introduction of the gas, Formed by the catalyst layer forming step,
  • the coating amount of the catalyst layer of the exhaust gas purifying catalyst is 20 to 110 g / L
  • the present invention it is possible to provide a production method capable of stably obtaining an exhaust gas purifying catalyst having enhanced soot trapping performance with good reproducibility, and an exhaust gas purifying catalyst obtained by the production method.
  • the exhaust gas purifying catalyst can be effectively used as a gasoline particulate filter (GPF) supporting the catalyst, and the performance of an exhaust gas treatment system equipped with such a particulate filter can be further enhanced.
  • GPF gasoline particulate filter
  • FIG. 3 is a process chart schematically showing a method for manufacturing the exhaust gas purifying catalyst of the embodiment. It is a sectional view showing typically one mode of an exhaust gas purification catalyst of this embodiment. It is sectional drawing which shows typically one aspect of the catalyst layer in the partition of the exhaust gas purification catalyst obtained using the catalyst slurry which does not have thixotropy. It is a sectional view showing typically one mode of a catalyst layer in a partition of an exhaust gas purifying catalyst of this embodiment.
  • FIG. 2 is a trace diagram showing a cross section of the exhaust gas purifying catalyst of the first embodiment.
  • FIG. 4 is a trace diagram showing a cross section of the exhaust gas purifying catalyst of Comparative Example 1.
  • a numerical value or a property value when inserted before and after using “to”, it is used as including the values before and after.
  • a numerical range notation of “1 to 100” includes both the lower limit value “1” and the upper limit value “100”. The same applies to the notation of other numerical ranges.
  • the production method according to the present embodiment is a method for producing an exhaust gas purifying catalyst 100 for purifying exhaust gas discharged from a gasoline engine.
  • the production method includes an introduction cell 11 having an open end 11 a on the exhaust gas introduction side, and an introduction cell 11.
  • the stopping step S1c for stopping the introduction, and firing the coated catalyst slurry 21a, the coating amount of the catalyst layer (the coating amount of the catalyst layer excluding the catalyst metal mass per 1 L of the wall flow type substrate) is
  • the wall flow type base material before forming the catalyst layer 21 is referred to as “base material 10”
  • the wall flow type base material after forming the catalyst layer 21 is referred to as “exhaust gas purifying catalyst 100”.
  • a wall flow type substrate is prepared as a substrate.
  • the wall flow type base material 10 has an introduction-side cell 11 having an open end 11a on the exhaust gas introduction side, and a discharge-side cell 12 having an open end 12a on the exhaust gas discharge side adjacent to the introduction-side cell 11 having a porous structure. It has a wall flow type structure which is separated by a quality partition wall 13.
  • the material of the base material may be exposed to high-temperature (for example, 400 ° C. or more) exhaust gas generated when the internal combustion engine is operated under high load conditions, or may be used to burn and remove particulate matter at a high temperature.
  • a material made of a heat-resistant material is preferable so as to be compatible.
  • the heat-resistant material include ceramics such as cordierite, mullite, aluminum titanate, and silicon carbide (SiC); and alloys such as stainless steel.
  • the shape of the base material can be appropriately adjusted from the viewpoint of exhaust gas purification performance, suppression of pressure loss rise, and the like.
  • the outer shape of the substrate can be a cylindrical shape, an elliptical cylindrical shape, a polygonal cylindrical shape, or the like.
  • the capacity of the base material is preferably 0.1 to 5 L, more preferably 0.5 to 3 L, depending on the space into which the substrate is to be incorporated.
  • the total length of the substrate in the stretching direction is preferably 10 to 500 mm, more preferably 50 to 300 mm.
  • the introduction-side cell 11 and the discharge-side cell 12 are regularly arranged along the axial direction of the cylindrical shape, and adjacent cells alternately have one open end and the other open end in the extending direction. It is sealed.
  • the introduction-side cell 11 and the discharge-side cell 12 can be set to appropriate shapes and sizes in consideration of the flow rate and components of the supplied exhaust gas.
  • the opening shapes of the inlet-side cell 11 and the outlet-side cell 12 can be triangular; rectangular such as square, parallelogram, rectangular, and trapezoidal; other polygons such as hexagonal and octagonal; circular.
  • the cross-sectional area of the introduction-side cell 11 and the cross-sectional area of the discharge-side cell 12 may have a High Ash Capacity (HAC) structure.
  • HAC High Ash Capacity
  • the number of the introduction-side cells 11 and the number of the discharge-side cells 12 can be appropriately set so as to promote the generation of turbulent flow of exhaust gas and to suppress clogging due to fine particles and the like contained in the exhaust gas.
  • 200 cpsi to 400 cpsi is preferred.
  • the partition 13 that separates adjacent cells is not particularly limited as long as it has a porous structure through which exhaust gas can pass, and its configuration is limited to exhaust gas purification performance, suppression of increase in pressure loss, and mechanical strength of a substrate. It can be adjusted appropriately from the viewpoint of improvement of the quality.
  • the catalyst layer 21 is formed on the pore surface in the partition wall 13 using a catalyst slurry 21a described later, the pore diameter (for example, the mode diameter (the pore diameter having the largest appearance ratio in the pore diameter frequency distribution (the When the maximum value))) or the pore volume is large, the pores are not easily blocked by the catalyst layer 21, and the resulting exhaust gas purifying catalyst tends to have a low pressure loss.
  • the pore diameter (mode diameter) of the partition walls 13 of the wall flow type substrate 10 before the formation of the catalyst layer 21 is preferably 8 to 25 ⁇ m, more preferably 10 to 22 ⁇ m, and furthermore Preferably it is 13 to 20 ⁇ m.
  • the thickness (length in the thickness direction orthogonal to the stretching direction) of the partition wall 13 is preferably 6 to 12 mil, and more preferably 6 to 10 mil.
  • the pore volume of the partition wall 13 by the mercury intrusion method is preferably 0.2 to 1.5 cm 3 / g, more preferably 0.25 to 0.9 cm 3 / g, and still more preferably 0.3 to 0.9 cm 3 / g. 0.80.8 cm 3 / g.
  • the porosity of the partition walls 13 by the mercury intrusion method is preferably 20 to 80%, more preferably 40 to 70%, and further preferably 60 to 70%.
  • the pore volume or the porosity is equal to or more than the lower limit, an increase in pressure loss tends to be further suppressed.
  • the pore volume or the porosity is equal to or less than the upper limit, the strength of the base material tends to be further improved.
  • the pore diameter (mode diameter), the pore volume, and the porosity mean values calculated by the mercury intrusion method under the conditions described in the following Examples.
  • the catalyst layer forming step S1 includes an impregnating step S1a of impregnating the end portion 11a on the exhaust gas introduction side or the end portion 12a on the exhaust gas discharge side of the wall flow type substrate 10 with a thixotropic catalyst slurry 21a, and a catalyst slurry 21a.
  • a thixotropic catalyst slurry 21a is used in which the viscosity is reduced by applying a shear stress and the viscosity is increased by standing without applying a shear stress.
  • the viscosity of the catalyst slurry 21a is reduced by the stress applied by the introduction of the gas F, so that the catalyst slurry 21a is uniformly coated on the pore surfaces of the porous partition walls 13.
  • the stopping step S1c the viscosity of the catalyst slurry 21a is increased, so that the coated catalyst slurry 21a is prevented from moving in the pores of the partition walls, and segregation or uneven distribution of the catalyst layer is suppressed. can do.
  • by suppressing the occurrence of pore blockage or coating unevenness due to segregation or uneven distribution of the catalyst layer it is possible to maintain a relatively high porosity and relatively small pore diameter.
  • the suppression of segregation or uneven distribution of the catalyst layer is not particularly limited, but is considered as follows.
  • the coated catalyst slurry 21a tends to move to a position where the area of the solid-liquid interface, that is, the contact area with the pore surface of the partition wall 13, increases due to the balance of the surface tension at the gas-liquid interface and the solid-liquid interface. . Therefore, in general, as the volume decreases due to the drying, the catalyst slurry 21a becomes narrower because the contact area with the pore surface of the partition wall 13 such as the small pores 13a having a relatively small pore diameter or the bag-like portion 13b having a bag-like shape is increased. And the catalyst layer tends to be segregated or unevenly distributed (see FIG. 3).
  • the catalyst slurry 21a after being applied has a high viscosity, so that the movement of the catalyst slurry 21a to the narrow portion is suppressed, so that the small pores 13a are closed or the catalyst is formed in the bag-like portion 13b. Concentration of the slurry 21a can be suppressed, and segregation or uneven distribution of the catalyst layer can be suppressed (see FIG. 4).
  • the method of applying the catalyst slurry 21a is not particularly limited, but for example, a method of impregnating a part of the base material 10 with the catalyst slurry 21a and spreading the impregnated catalyst slurry 21a over the entire partition 13 of the base material 10 can be mentioned. More specifically, the step S1a of impregnating the catalyst slurry 21a into the end 11a on the exhaust gas introduction side or the end 12a on the exhaust gas discharge side of the base material 10 and the base material from the end side impregnated with the catalyst slurry 21a A method including a coating step S1b of coating the partition walls 13 with the catalyst slurry 21a impregnated in the base material 10 by introducing a gas into the base material 10 is exemplified.
  • the method of impregnating the catalyst slurry 21a in the impregnation step S1a is not particularly limited, and for example, a method of immersing the end of the base material 10 in the catalyst slurry 21a can be used. In this method, if necessary, the catalyst slurry 21a may be pulled up by discharging (sucking) gas from the opposite end.
  • the end for impregnating the catalyst slurry 21a may be either the end 11a on the exhaust gas introduction side or the end 12a on the exhaust gas discharge side, but it is preferable to impregnate the end 11a on the exhaust gas introduction side with the catalyst slurry 21a.
  • the gas can be introduced in the step S1b in the same direction as the exhaust gas introduction direction, and the catalyst slurry 21a can be applied to a complicated pore shape along the flow of the exhaust gas. Therefore, suppression of a rise in pressure loss of the obtained exhaust gas purifying catalyst is expected, and improvement in exhaust gas purifying performance can be expected.
  • the viscosity of the impregnated catalyst slurry 21a is reduced by the stress applied by the introduction of the gas F, and the reduced viscosity of the catalyst slurry 21a is reduced by the flow of the gas F from the introduction side of the base material 10 to the back. Along the air, and reaches the end on the discharge side of the gas F.
  • the catalyst slurry 21a can be applied to the inside of the pores by passing the catalyst slurry 21a through the inside of the pores of the partition 13, and the catalyst slurry 21a is applied to the entire partition.
  • the manufacturing method of the present embodiment may include a drying step of drying the applied catalyst slurry 21a after the stopping step S1c.
  • the drying condition in the drying step is not particularly limited as long as the solvent evaporates from the catalyst slurry 21a.
  • the drying temperature is preferably from 100 to 225 ° C, more preferably from 100 to 200 ° C, and even more preferably from 125 to 175 ° C.
  • the drying time is preferably 0.5 to 2 hours, and preferably 0.5 to 1.5 hours.
  • the catalyst slurry 21a uniformly coated as described above is fired to form the catalyst layer 21.
  • the firing conditions in the firing step S1d are not particularly limited as long as the catalyst layer 21 can be formed from the catalyst slurry 21a.
  • the firing temperature is not particularly limited, but is preferably from 400 to 650 ° C, more preferably from 450 to 600 ° C, and still more preferably from 500 to 600 ° C.
  • the firing time is preferably 0.5 to 2 hours, preferably 0.5 to 1.5 hours.
  • the coating amount of the catalyst layer of the exhaust gas purifying catalyst 100 obtained through the firing step S1d is preferably 20 to 110 g / L, more preferably 40 to 90 g / L, and further preferably 50 to 70 g. / L.
  • the catalyst slurry 21a for forming the catalyst layer 21 will be described.
  • the catalyst slurry 21a used in the present embodiment has thixotropic properties.
  • thixotropic refers to a property in which the viscosity decreases with time when flowing at a constant shear rate, and then returns to the original viscosity again after stopping the flow and resting for a while.
  • viscosity in the present embodiment refers to a value measured using a rheometer at a predetermined shear rate at 25 ° C.
  • the viscosity ⁇ 10 at a shear rate of 10 s ⁇ 1 is preferably 50 to 1500 mPa ⁇ s, more preferably 200 to 1300 mPa ⁇ s, and still more preferably 300 to 1200 mPa ⁇ s.
  • Viscosity eta 10 is obtained by assuming the viscosity of the catalyst slurry is coated on the pores surface in the partition wall, by an in viscosity eta 10 above range, movement in the pores of the catalyst slurry 21a was coated is suppressed There is a tendency. Thereby, it is possible to suppress the small pores 13a from being closed or the catalyst slurry 21a from being concentrated on the bag-like portion 13b, and to suppress segregation or uneven distribution of the catalyst layer.
  • the viscosity ⁇ 550 at a shear rate of 550 s ⁇ 1 is preferably 5 to 30 mPa ⁇ s, It is more preferably 5 to 20 mPa ⁇ s, and still more preferably 5 to 15 mPa ⁇ s.
  • the viscosity ⁇ 550 is based on the viscosity of the catalyst slurry at the time of coating. When the viscosity ⁇ 550 is within the above range, the uniform coating property of the catalyst slurry tends to be further improved.
  • the TI value is 10 to 100, preferably 20 to 80, and more preferably 40 to 80.
  • Thixotropic that is, the viscosity ⁇ 10 and the viscosity ⁇ 550 , and the TI value, which is the ratio thereof, can be adjusted by the solid content and the pH of the catalyst slurry 21a.
  • the catalyst slurry 21a contains a catalyst powder, a solvent such as water, and a pH adjuster.
  • the catalyst powder is a group of a plurality of catalyst particles including catalyst metal particles and carrier particles supporting the catalyst metal particles, and forms the catalyst layer 21 through a firing step S1d described later.
  • the catalyst particles are not particularly limited, and can be appropriately selected from known catalyst particles and used.
  • the solid content of the catalyst slurry 21a is preferably 1 to 50% by mass, more preferably 10 to 50% by mass, still more preferably 15 to 40% by mass, and particularly preferably 20 to 35% by mass. is there.
  • thixotropicity that is, viscosity ⁇ 10 and viscosity ⁇ 550 can be adjusted.
  • the D90 particle size of the catalyst powder contained in the catalyst slurry 21a is preferably 1 to 7 ⁇ m, more preferably 1 to 5 ⁇ m, and still more preferably 1 to 3 ⁇ m.
  • the D90 particle diameter is 1 ⁇ m or more, the pulverization time when the catalyst powder is crushed by a milling device can be reduced, and the working efficiency tends to be further improved.
  • the D90 particle size is 7 ⁇ m or less, the coarse particles are suppressed from closing the inside of the partition wall 13 and the increase in pressure loss tends to be suppressed.
  • the D90 particle size can be measured with a laser diffraction particle size distribution analyzer (eg, a laser diffraction particle size distribution analyzer SALD-3100 manufactured by Shimadzu Corporation).
  • the catalyst metal contained in the catalyst slurry 21a is not particularly limited, and various metal species that can function as an oxidation catalyst or a reduction catalyst can be used.
  • platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os) can be used.
  • palladium (Pd) and platinum (Pt) are preferable from the viewpoint of oxidation activity
  • rhodium (Rh) is preferable from the viewpoint of reduction activity.
  • oxygen storage materials such as cerium oxide (ceria: CeO 2 ) and ceria-zirconia composite oxide (CZ composite oxide), aluminum oxide (alumina: Al 2 O 3 ), zirconium oxide (zirconia: ZrO 2 ) 2 ), oxides such as silicon oxide (silica: SiO 2 ), titanium oxide (titania: TiO 2 ), and composite oxides containing these oxides as main components.
  • OSC materials oxygen storage materials
  • cerium oxide ceria: CeO 2
  • CZ composite oxide ceria-zirconia composite oxide
  • aluminum oxide alumina: Al 2 O 3
  • zirconium oxide zirconia: ZrO 2
  • oxides such as silicon oxide (silica: SiO 2 ), titanium oxide (titania: TiO 2 ), and composite oxides containing these oxides as main components.
  • the carrier particles may be a composite oxide or a solid solution to which a rare earth element such as lanthanum or yttrium, a transition metal element, or an alkaline earth metal element is added.
  • These carrier particles may be used alone or in combination of two or more.
  • the oxygen storage material means that when the air-fuel ratio of the exhaust gas is lean (that is, the atmosphere on the oxygen excess side), oxygen in the exhaust gas is stored and the air-fuel ratio of the exhaust gas is rich ( That is, the atmosphere that releases the occluded oxygen is referred to as the atmosphere on the side of excess fuel.
  • the specific surface area of the carrier particles contained in the catalyst slurry is preferably from 10 to 500 m 2 / g, and more preferably from 30 to 200 m 2 / g.
  • the pH adjuster contained in the catalyst slurry is not particularly limited, and includes, for example, at least one selected from the group consisting of methylamine, dimethylamine, trimethylamine, barium hydroxide, ammonium carbonate, ammonium hydrogen carbonate, and aqueous ammonia.
  • thixotropic that is, the viscosity ⁇ 10 and the viscosity ⁇ 550 can be adjusted, and in particular, the viscosity ⁇ 10 can be higher and the viscosity ⁇ 550 can be lower.
  • barium hydroxide is preferred from the viewpoint that the degree of ionization is large, that is, the pH can be adjusted with a small amount, and it is easily dispersed uniformly in the catalyst slurry.
  • methylamine, dimethylamine, trimethylamine, ammonium carbonate, ammonium hydrogen carbonate, and aqueous ammonia are preferable, and ammonium carbonate is more preferable.
  • the pH of the catalyst slurry is preferably 3 to 10, more preferably 4 to 9, and even more preferably 5 to 8.
  • thixotropic that is, the viscosity ⁇ 10 and the viscosity ⁇ 550 can be adjusted, and in particular, the viscosity ⁇ 10 can be higher and the viscosity ⁇ 550 can be lower.
  • the pore diameter (mode diameter) of the partition wall 13 of the exhaust gas purifying catalyst 100 in the state where the catalyst layer 21 is formed by the mercury intrusion method is preferably 10 to 23 ⁇ m, more preferably 11 to 20 ⁇ m, and still more preferably. Is 12 to 18 ⁇ m.
  • the pore volume of the partition wall of the exhaust gas purifying catalyst in the state where the laminated catalyst layer is formed by a mercury intrusion method is preferably 0.2 to 1.0 cm 3 / g, more preferably 0.25 to 0 cm 3 / g. 0.9 cm 3 / g, and more preferably 0.3 to 0.8 cm 3 / g.
  • the porosity of the partition wall of the exhaust gas purifying catalyst in the state where the laminated catalyst layer is formed by a mercury intrusion method is preferably 20 to 80%, more preferably 30 to 70%, and preferably 35 to 70%. 60%.
  • the pore diameter (mode diameter), the pore volume, and the porosity mean values calculated by the mercury intrusion method under the conditions described in the following Examples.
  • the exhaust gas purifying catalyst is an exhaust gas purifying catalyst 100 for purifying exhaust gas discharged from a gasoline engine.
  • the exhaust gas purifying catalyst 100 includes an inlet cell 11 having an open end 11a on the exhaust gas inlet side and an inlet cell 11 adjacent to the inlet cell 11.
  • the discharge-side cell 12 having an open end 12a on the exhaust gas discharge side comprises a wall flow-type substrate 10 defined by a porous partition wall 13 and a catalyst layer 21 formed in pores of the partition wall 13.
  • the catalyst layer forming step S1 includes a coating step S1b for coating the partition walls 13, a stopping step S1c for stopping the introduction of the gas F, and a firing step S1d for firing the coated catalyst slurry 21a.
  • the coating amount of the catalyst layer of the exhaust gas purifying catalyst 100 is 20 to 110 g / L.
  • the exhaust gas purifying catalyst of the present embodiment has a wall flow type structure.
  • the exhaust gas discharged from the internal combustion engine flows into the introduction-side cell 11 from the end portion 11a (opening) on the exhaust gas introduction side, passes through the pores of the partition wall 13, and passes through. Flows into the adjacent discharge-side cell 12 and flows out from the end portion 12a (opening) on the exhaust gas discharge side.
  • the particulate matter (PM) that hardly passes through the pores of the partition 13 is generally deposited on the partition 13 in the introduction-side cell 11 and / or in the pores of the partition 13, and the deposited particulate matter is:
  • the fuel is removed by burning due to the catalytic function of the catalyst layer 21 or at a predetermined temperature (for example, about 500 to 700 ° C.).
  • the exhaust gas comes into contact with the catalyst layer 21 formed in the pores of the partition 13, whereby carbon monoxide (CO) and hydrocarbon (HC) contained in the exhaust gas are converted into water (H 2 O) and carbon dioxide ( CO 2 ) and the like, nitrogen oxides (NOx) are reduced to nitrogen (N 2 ), and harmful components are purified (made harmless).
  • the removal of particulate matter and the purification of harmful components such as carbon monoxide (CO) are also collectively referred to as “exhaust gas purification performance”.
  • each configuration will be described in more detail.
  • a catalyst layer is formed in the portion. Furthermore, the uneven distribution of the catalyst layer in the small pores 13a and the bag-like portions 13b in the partition walls is suppressed, so that a relatively large number of catalyst layers can be formed in other pores. Therefore, from the viewpoint of soot collection, a relatively large number of catalyst layers are formed on the surface of the air holes 13c that are too large, and the soot collection rate in the air holes 13c is improved by reducing the pore diameter. . That is, according to the catalyst layer 21 formed in the catalyst layer forming step S1, the blockage of the small pores 13a is suppressed, and the pore diameter of the atmospheric pores 13c is appropriately narrowed, so that the soot collection rate is reduced. Can be improved. However, the reason why the soot collection rate is improved is not limited to the above.
  • the catalyst layer 21 is preferably formed from the cell wall on the introduction side cell 11 side to the cell wall on the discharge side cell 12 side in the thickness direction of the partition wall 13. In the direction (length direction), it is preferable that the entirety be formed.
  • the catalyst layer 21 can be confirmed by a scanning electron microscope on the cross section of the partition wall 13 of the exhaust gas purifying catalyst 100.
  • the catalyst metal contained in the catalyst layer 21 is not particularly limited, and various metal species that can function as various oxidation catalysts and reduction catalysts can be used.
  • platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os) can be used.
  • palladium (Pd) and platinum (Pt) are preferable from the viewpoint of oxidation activity
  • rhodium (Rh) is preferable from the viewpoint of reduction activity.
  • the catalyst layer 21 contains one or more catalyst metals in a mixed state as described above. In particular, when two or more kinds of catalyst metals are used in combination, a synergistic effect due to having different catalytic activities is expected.
  • the embodiment of the combination of such catalyst metals is not particularly limited, and a combination of two or more catalyst metals having excellent oxidation activity, a combination of two or more catalyst metals having excellent reduction activity, and a catalyst metal having excellent oxidation activity and reduction. Combinations of catalyst metals having excellent activity are mentioned. Among these, as one aspect of the synergistic effect, a combination of a catalyst metal having excellent oxidation activity and a catalyst metal having excellent reduction activity is preferable, and a combination containing at least Rh, Pd and Rh, or Pt and Rh is more preferable. With such a combination, the exhaust gas purification performance tends to be further improved.
  • the fact that the catalyst layer 21 contains the catalyst metal can be confirmed by a scanning electron microscope or the like on the cross section of the partition wall 13 of the exhaust gas purifying catalyst. Specifically, it can be confirmed by performing energy dispersive X-ray analysis in the field of view of a scanning electron microscope.
  • oxygen storage materials such as cerium oxide (ceria: CeO 2 ) and ceria-zirconia composite oxide (CZ composite oxide), aluminum oxide (alumina: Al 2 O 3 ), zirconium oxide (zirconia: ZrO 2 ) 2 ), oxides such as silicon oxide (silica: SiO 2 ), titanium oxide (titania: TiO 2 ), and composite oxides containing these oxides as main components.
  • OSC materials oxygen storage materials
  • cerium oxide ceria: CeO 2
  • CZ composite oxide ceria-zirconia composite oxide
  • aluminum oxide alumina: Al 2 O 3
  • zirconium oxide zirconia: ZrO 2
  • oxides such as silicon oxide (silica: SiO 2 ), titanium oxide (titania: TiO 2 ), and composite oxides containing these oxides as main components.
  • the oxygen storage material means that when the air-fuel ratio of the exhaust gas is lean (that is, the atmosphere on the oxygen excess side), oxygen in the exhaust gas is stored and the air-fuel ratio of the exhaust gas is rich ( That is, the atmosphere that releases the occluded oxygen is referred to as the atmosphere on the side of excess fuel.
  • the coating amount of the catalyst layer of the exhaust gas purifying catalyst 100 is preferably 20 to 110 g / L, more preferably 40 to 90 g / L, and further preferably 50 to 70 g / L.
  • the pore diameter (mode diameter) of the partition wall 13 of the exhaust gas purifying catalyst 100 in the state where the catalyst layer 21 is formed by the mercury intrusion method is preferably 10 to 23 ⁇ m, more preferably 12 to 20 ⁇ m, and still more preferably. Is 14 to 18 ⁇ m.
  • the pore volume of the partition wall 13 of the exhaust gas purifying catalyst in the state where the catalyst layer 21 is formed by the mercury intrusion method is preferably 0.2 to 1.0 cm 3 / g, more preferably 0.25 to 0. It is 9 cm 3 / g, and more preferably 0.3 to 0.8 cm 3 / g.
  • the porosity of the partition wall 13 of the exhaust gas purifying catalyst 100 in the state where the catalyst layer 21 is formed by the mercury intrusion method is preferably 20 to 80%, more preferably 30 to 70%, and preferably 35 to 70%. 60%.
  • the pore diameter (mode diameter), the pore volume, and the porosity mean values calculated by the mercury intrusion method under the conditions described in the following Examples.
  • An air-fuel mixture containing oxygen and fuel gas is supplied to an internal combustion engine, and the air-fuel mixture is burned to convert combustion energy into mechanical energy.
  • the air-fuel mixture burned at this time is discharged as exhaust gas to an exhaust system.
  • the exhaust system is provided with an exhaust gas purifying device provided with an exhaust gas purifying catalyst, and harmful components (for example, carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) contained in exhaust gas by the exhaust gas purifying catalyst are provided. )) Is purified, and particulate matter (PM) contained in the exhaust gas is collected and removed.
  • the exhaust gas purifying catalyst 100 of the present embodiment is preferably used for a gasoline particulate filter (GPF) that can collect and remove particulate matter contained in exhaust gas of a gasoline engine.
  • GPF gasoline particulate filter
  • Example 1 The alumina powder and the ceria-zirconia composite oxide powder were impregnated with an aqueous solution of palladium nitrate, and then calcined at 500 ° C. for 1 hour to obtain a Pd-supported powder.
  • the zirconia powder was impregnated with an aqueous solution of rhodium nitrate, and then calcined at 500 ° C. for 1 hour to obtain a Rh-supported powder.
  • the viscosity ⁇ 10 when the shear rate of the obtained catalyst slurry is 10 s ⁇ 1 is 616 mPa ⁇ s
  • the viscosity ⁇ 550 when the shear rate is 550 s ⁇ 1 is 15 mPa ⁇ s
  • the viscosity ⁇ The ratio of the viscosity ⁇ 10 to 550 ( ⁇ 10 / ⁇ 550 ), that is, the TI value, was 41.
  • a cordierite wall flow type honeycomb substrate (cell number / mil thickness: 300 cpsi / 8.5 mil, diameter: 118.4 mm, total length: 127 mm, pore diameter (mode diameter): 20 ⁇ m, porosity: 65%) was prepared.
  • the end of the base material on the exhaust gas introduction side was immersed in the catalyst slurry, and vacuum suction was performed from the opposite end side to impregnate and hold the catalyst slurry at the end of the base material.
  • the base material coated with the catalyst slurry was dried at 150 ° C., and then calcined at 550 ° C. in an air atmosphere to prepare an exhaust gas purifying catalyst.
  • the coating amount of the catalyst layer after the firing was 58.8 g (excluding the weight of the platinum group metal) per 1 L of the base material.
  • Comparative Example 1 An exhaust gas purifying catalyst was prepared in the same manner as in Example 1, except that 32 g of barium hydroxide octahydrate and ammonium carbonate were not added in the preparation of the catalyst slurry.
  • the pH of the catalyst slurry used in Comparative Example 1 was 4.2.
  • the D90 particle size of the catalyst slurry was measured by a laser scattering method using a laser diffraction particle size distribution analyzer SALD-3100 manufactured by Shimadzu Corporation.
  • Viscosity measurement The viscosity ⁇ 10 and the viscosity ⁇ 550 were measured at 25 ° C using a rheometer HAAKE MARS II manufactured by Thermo Fisher Scientific.
  • the pore diameter (mode diameter) was obtained, and the pore volume of pores having a pore diameter of 1 ⁇ m or more was calculated.
  • the values of the pore diameter and the pore volume the average values of the values obtained in the exhaust gas introduction side portion, the exhaust gas discharge side portion, and the intermediate portion were used.
  • the soot collection rate of the example was 73.8%
  • the soot collection rate of the comparative example was 60.2%
  • the soot collection rate of the base material itself was 67.4%.
  • the small pores are not closed and the pore diameter of the atmospheric holes is reduced, thereby improving the soot collection rate.
  • the small pores are closed,
  • the catalyst layer is also arranged on the bag-shaped portion, the pore diameter of the atmospheric pores is not small, which suggests that the soot collection rate is lower than that of the base material.
  • the exhaust gas purifying catalyst of the present invention can be widely and effectively used as an exhaust gas purifying catalyst for removing particulate matter contained in exhaust gas of a gasoline engine. Further, the exhaust gas purifying catalyst of the present invention can be effectively used as an exhaust gas purifying catalyst for removing particulate matter contained in exhaust gas of not only gasoline engines but also jet engines, boilers, gas turbines and the like.

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Citations (5)

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WO2007026804A1 (ja) * 2005-08-31 2007-03-08 Ngk Insulators, Ltd. ハニカム触媒体、及びハニカム触媒体の製造方法
JP2009011934A (ja) * 2007-07-04 2009-01-22 Cataler Corp スラリーの粘度調整方法およびスラリーの製造方法
WO2009028422A1 (ja) * 2007-08-27 2009-03-05 Tokyo Roki Co. Ltd. 排ガス浄化用触媒の製造方法、及び排ガス浄化用触媒
WO2016060048A1 (ja) * 2014-10-16 2016-04-21 株式会社キャタラー 排ガス浄化用触媒
JP2017159252A (ja) * 2016-03-10 2017-09-14 株式会社キャタラー 排ガス浄化用触媒

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US4923830A (en) * 1989-09-18 1990-05-08 Swiss Aluminum Ltd. Ceramic bodies formed from partially stabilized zirconia
CN1169752C (zh) * 2000-10-27 2004-10-06 中国科学院上海硅酸盐研究所 一种高强度网眼多孔陶瓷的制造方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007026804A1 (ja) * 2005-08-31 2007-03-08 Ngk Insulators, Ltd. ハニカム触媒体、及びハニカム触媒体の製造方法
JP2009011934A (ja) * 2007-07-04 2009-01-22 Cataler Corp スラリーの粘度調整方法およびスラリーの製造方法
WO2009028422A1 (ja) * 2007-08-27 2009-03-05 Tokyo Roki Co. Ltd. 排ガス浄化用触媒の製造方法、及び排ガス浄化用触媒
WO2016060048A1 (ja) * 2014-10-16 2016-04-21 株式会社キャタラー 排ガス浄化用触媒
JP2017159252A (ja) * 2016-03-10 2017-09-14 株式会社キャタラー 排ガス浄化用触媒

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