WO2009144568A1 - Catalyseur de purification de gaz de combustion - Google Patents

Catalyseur de purification de gaz de combustion Download PDF

Info

Publication number
WO2009144568A1
WO2009144568A1 PCT/IB2009/005749 IB2009005749W WO2009144568A1 WO 2009144568 A1 WO2009144568 A1 WO 2009144568A1 IB 2009005749 W IB2009005749 W IB 2009005749W WO 2009144568 A1 WO2009144568 A1 WO 2009144568A1
Authority
WO
WIPO (PCT)
Prior art keywords
catalyst
layer
upper layer
contained
exhaust 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
Application number
PCT/IB2009/005749
Other languages
English (en)
Inventor
Naoto Miyoshi
Takeshi Nobukawa
Kenji Sakurai
Kenji Katoh
Hiroto Imai
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cataler Corp
Toyota Motor Corp
Original Assignee
Cataler Corp
Toyota Motor Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Cataler Corp, Toyota Motor Corp filed Critical Cataler Corp
Publication of WO2009144568A1 publication Critical patent/WO2009144568A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/9454—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific device
    • 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
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B01D53/9422—Processes characterised by a specific catalyst for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)
    • 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
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9431—Processes characterised by a specific device
    • 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
    • B01J23/58—Platinum group metals with alkali- or alkaline earth metals
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0242—Coating followed by impregnation
    • 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
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0244—Coatings comprising several layers
    • 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
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0248—Coatings comprising impregnated particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/208—Hydrocarbons
    • 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
    • B01D2255/102—Platinum group metals
    • B01D2255/1021—Platinum
    • 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
    • B01D2255/102—Platinum group metals
    • B01D2255/1023—Palladium
    • 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
    • B01D2255/102—Platinum group metals
    • B01D2255/1025—Rhodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/902—Multilayered catalyst
    • B01D2255/9022—Two layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/91—NOx-storage component incorporated in the catalyst
    • 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
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/066—Zirconium or hafnium; Oxides or hydroxides thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to an exhaust purification catalyst that purifies exhaust gas from an internal combustion engine. More specifically, the present invention relates to a NOx storage-reduction exhaust purification catalyst that stores NOx when the air-fuel ratio of the exhaust gas is lean and reduces the stored NOx when the air-fuel ratio of the exhaust gas is stoichiometric or rich.
  • the NOx storage-reduction catalyst is in practical use as a catalyst to purify exhaust gas from a lean-burn engine.
  • the NOx storage-reduction catalyst is composed of a porous carrier made of a material such as alumina (AI 2 O 3 ) and a NOx storing material such as an alkaline metal or alkaline-earth metal and a noble metal supported on the carrier.
  • a NOx storage-reduction catalyst if the fuel injection is controlled in a pulse manner so that the air-fuel ratio between a lean air-fuel ratio and a stoichiometric to rich air-fuel ratio, NOx is stored in the NOx storing material when the air-fuel ratio is lean.
  • the stored NOx is released when the air-fuel ratio is rich and reacted with and purified by reducing components such as HC and CO by the catalytic action of the noble metal. Therefore, emission of NOx may be reduced on the lean side as well, and a high NOx purification capability can be achieved as a whole.
  • Rhodium primarily contributes to reduction purification of NOx.
  • Rhodium also prevents sintering of Pt or Pd.
  • a noble metal species and a type of carrier that should be avoided under certain usage conditions.
  • a catalyst composed of Rh supported on alumina may have a defect that the Rh forms a solid solution in the alumina and significantly deteriorates in performance in an oxidation atmosphere at a temperature of 900 0 C or higher.
  • Rh is a very rare resource and it is therefore desired to use Rh efficiently and prevent deterioration of Rh to improve the heat resistance properties.
  • Exhaust gas of motor vehicles contains SO 2 generated from the combustion of sulfur (S) contained in the fuel, and it is oxidized by the noble metal into SO3 when it passes through the NOx storage-reduction catalyst in an oxygen-excess atmosphere. It has been found that the SO3 and water vapor contained in exhaust gas easily form sulfuric acid, which in turn reacts with the NOx storing material to form sulfites and sulfates that poison and deteriorate the NOx storing material. This phenomenon is called sulfur poisoning. When the NOx storing material is poisoned by sulfur as described above, it can no longer store NOx, resulting in deterioration in the NOx purification capability.
  • JP-A- 11 -226404 describes a NOx storage-reduction catalyst having a catalyst coating formed from a mixture of a first powder obtained by depositing Pt and a NOx storing material on alumina and titania and a second powder obtained by depositing Rh on stabilized zirconia.
  • zirconia on which Rh is deposited as described above, formation of a solid solution of Rh in alumina may be avoided and therefore deterioration of Rh may be inhibited.
  • a decrease in the activity of Pt caused by alloying of Pt with Rh may also be inhibited because Pt and Rh are separated from each other, and sintering of Pt may be inhibited because Pt and Rh are located relatively close to each other.
  • Rh deposited on zirconia exhibits an ability to generate hydrogen through a steam-reforming reaction. Therefore, according to the catalyst described in JP-A-11-226404, NO is oxidized by the high oxidation activity of Pt and stored in the NOx storing material in a lean atmosphere, and the stored NOx is released and efficiently reduced by the hydrogen generated in a stoichiometric to rich atmosphere. Also, the sulfites and sulfate on the NOx storing material are reduced by the hydrogen, and the NOx storing material recovers its NOx storage capacity. Therefore, the NOx purification performance significantly improves.
  • JP-A-06-039292 Japanese Patent Application Publication No. 06-039292
  • JP-A-2001-182527 Japanese Patent Application Publication No. 2001-182527
  • the present invention enables Pt and Rh to fulfill their functions to the maximum and further improves the NOx purification performance.
  • a NOx storage-reduction exhaust purification catalyst includes a NOx storing material which stores NOx when the air-fuel ratio of the exhaust gas is leans, and reduces the stored NOx when the air-fuel ratio of the exhaust gas is stoichiometric or rich
  • the exhaust purification catalyst including: a carrier substrate; and a catalyst coat layer formed on a surface of the carrier substrate and containing an oxide carrier on which at least one NOx storing material selected from alkaline metal, alkaline-earth metal or rare earth elements, at least one of platinum and palladium, and rhodium are supported, wherein the catalyst coat layer has a two-layer structure including a lower layer formed on a surface of the carrier substrate, and an upper layer formed on a surface of the lower layer, and the at least one of platinum and palladium is present in at least the upper layer, and the proportion of Rh contained in the lower layer is higher than the proportion of Rh contained in upper layer.
  • 40% by mass or less of the total amount of rhodium contained in the catalyst coat layer may be present in the upper layer and 60% by mass or more of the total amount of rhodium contained in the catalyst coat layer may be present in the lower layer.
  • the exhaust purification catalyst in the exhaust purification catalyst according to this aspect of the present invention, at least one of Pt and Pd is contained at least in the upper layer.
  • the NO contained in exhaust gas is efficiently oxidized into NOx by Pt or Pd in the upper layer in a lean atmosphere and stored in the NOx storing material contained at least in the upper layer.
  • the proportion of Rh contained in the lower layer is higher than that contained in the upper layer. Therefore, hydrogen is generated primarily in the lower layer in a stoichiometric to rich atmosphere, and the hydrogen unavoidably passes through the upper layer.
  • the NOx released from the NOx storing material at least in the upper layer is efficiently reduced and purified by the hydrogen.
  • the sulfur compounds are reduced by the hydrogen and the NOx storing material recovers its NOx storage capacity.
  • FIG 1 is a schematic explanatory view illustrating a catalyst according to one embodiment of the present invention.
  • FIG 2 is a graph showing the relation between the proportion of Rh contained in a lower layer and the NOx purification efficiency
  • FIG 3 is a bar graph showing the NO conversion rate
  • FIG 4 is a bar graph showing the amount of hydrogen generation.
  • An exhaust purification catalyst according to an embodiment of the present invention is composed of a carrier substrate, and a catalyst coat layer.
  • the carrier substrate has a configuration such as a porous configuration or honeycomb configuration, and may be made of cordierite, ceramics such as SiC, or a metal, for example.
  • the exhaust purification catalyst has a honeycombconfiguration, it may be either of a straight-flow structure or a wall-flow structure.
  • Rh is preferably supported on zirconia.
  • a NOx storing material is contained at least in the upper layer. The reason for this is to increase the amount of NOx storing material contained in the vicinity of Pt or Pd. With this configuration, NOx generated by oxidation catalyzed by the Pt or Pd may be stored in the NOx storing material efficiently. It is needless to say that a portion of the NOx storing material may be contained in the lower layer.
  • the amount of NOx storing material contained is preferably in the range of 0.01 to 5 moles, more preferably in the range of 0.1 to 0.5 moles, per liter of the carrier substrate in the entire catalyst coat layer.
  • the amount is less than 0.01 moles/L, the NOx storage capacity is too low for practical use, and when NOx storing material is contained in an amount more than 5 moles/L, the activity of Pt is lowered.
  • the NOx storing material is contained in the upper layer in an amount of at least 0,01 moles/L or more. When the NOx storing material in the upper layer is smaller than that, the NOx purification performance is lowered.
  • the proportion (amount) of at least one of Pt and Pd contained in the upper layer is greater than half of the total amount thereof contained in the entire catalyst coat layer. It is desirably to maximize the amount of Pt or Pd contained in the upper layer, and it is permissible to have all the Pt or Pd contained in the upper layer.
  • the amounts of at least one of Pt and Pd and Rh contained are both preferably in the range of 0.1 to 10 g per liter of the carrier substrate in the entire catalyst coat layer. When the amounts are less than 0.1 g/L, the NOx purification activity is insufficient. When at least one of Pt and Pd and R are contained in an amount greater than 10 g/L, sintering tends to occur during endurance.
  • the catalyst coat layer is preferably in the range of 50 to 300 g per liter of the carrier substrate.
  • the Pt tends to undergo sintering.
  • a catalyst coat layer greater than 300 g/L is not preferred due to increases in the pressure loss of exhaust gas. While the coating amounts of the lower layer and the upper layer may be generally equal to each other, it is preferable for the upper layer containing a larger amount of Pt, which is apt to undergo sintering, is slightly thicker than the lower layer.
  • FIG. 1 depicts a catalyst according to this embodiment.
  • the NOx storage- reduction catalyst includes a honeycomb substrate 1, and a catalyst coat layer 2 formed over surfaces of cell walls 10 of the honeycomb substrate 1.
  • the catalyst coat layer 2 is composed of a lower layer 20 formed over the surfaces of the cell walls 10 and an upper layer 21 formed over a surface of the lower layer 20.
  • the method for producing the catalyst is described in substitution for detailed description of the configuration thereof.
  • RhZZjO 2 powder having 0.8% by mass of Rh supported thereon.
  • Rh/Zr ⁇ 2 powder of 100 parts by mass, an alumina sol (Al 2 O 3 : 10% by mass) of 30 parts by mass as a binder, and distilled water were mixed to prepare a slurry.
  • a 1.3 L cordierite honeycomb substrate 1 was immersed in and lifted out of the slurry, and excess slurry was blown off. Then, the honeycomb substrate 1 was dried and baked to form a lower layer 20.
  • the lower layer 20 was formed in an amount of 50 g per liter of the honeycomb substrate 1.
  • the lower layer 20 contains 0.4 g of Rh per liter of the carrier substrate.
  • RhZZrO 2 powder of 10 parts by mass, Al 2 O 3 powder of 85 parts by mass, Ce ⁇ 2-Zr ⁇ 2 composite oxide powder of 20 parts by mass, Z ⁇ O 2 -Ti ⁇ 2 composite oxide powder of 85 parts by mass, an alumina sol (AI2O3: 10% by mass) of 60 parts by mass, and distilled water were mixed to prepare a slurry.
  • the honeycomb substrate 1, on which the lower layer 20 had been formed, was immersed in and lifted out of the slurry, and excess slurry was blown off. Then, the honeycomb substrate 1 was dried and baked to form an upper layer 21.
  • the upper layer 21 was formed in an amount of 200 g per liter of the honeycomb substrate 1.
  • the upper layer 21 contains 0.1 g of Rh per liter of the honeycomb substrate 1. That is, 80% by mass of Rh was contained in the lower layer 20, and 20% by mass of Rh was contained in the upper layer 21.
  • the honeycomb substrate 1 was dried, and then impregnated with a prescribed amount of a mixed aqueous solution of barium acetate and potassium acetate having a prescribed concentration. The solution was evaporated and dried, and the honeycomb substrate 1 was baked so that Ba and K were deposited in the honeycomb substrate 1. About 80% of the total amount of Ba and K was deposited in the upper layer 21, and about 20% of the total amount of Ba and K was deposited in the lower layer 20. Ba and K were contained in an amount of 0.2 moles and 0.1 moles, respectively, per liter of the honeycomb substrate 1 in the entire catalyst coat layer.
  • Example 2 A catalyst of Example 2 was prepared in the same manner as in Example 1 except that the amount of the Rh/ZrCh powder was controlled so that the lower layer 20 contained 0.3 g/L of Rh and the upper layer 21 contained 0.2 g/L of Rh. In other words, 60% by mass of IUi was contained in the lower layer 20, and 40% by mass of Rh was contained in the upper layer 21.
  • Comparative Example 1 A catalyst of Comparative Example 1 was prepared in the same manner as in Example 1 except that the amount of Rh/ZrCh powder was controlled so that the lower layer 20 contained 0.25 g/L of Rh and the upper layer 21 contained 0.25 g/L of EIh. That is, 50% by mass of Rh was contained in the lower layer 20, and 50% by mass of Rh was contained in the upper layer 21.
  • Each of the above catalysts was installed in the exhaust system of an engine bench equipped with a lean-burn engine, and an endurance test in which a catalyst bed temperature of 750 ⁇ C was maintained for 50 hours under the condition that a lean control and a rich control were alternately repeated was conducted using gasoline containing 100 ppm of sulfur.
  • Each of the catalysts after the endurance test was installed in the exhaust system of the same engine bench as above, and the NOx storage capacity at a time when a lean atmosphere was produced after a rich spike was measured under the condition that rich spike was introduced for one second after a lean atmosphere was maintained for one minute, and it was defined as NOx purification efficiency.
  • the catalyst bed temperature was 400 0 C.
  • the results are shown in FIG 2, in which the horizontal axis represents the amount of Rb in terms of percent by mass in the lower layer.
  • FIG 2 indicates that, when the amount of Rh contained in the lower layer 20 is 60% by mass or greater, the NOx purification efficiency after the endurance test becomes 90% or higher. This is believed that because alloying and sulfur poisoning are inhibited. It is also indicated that Rh is preferably contained in the upper layer 21 as well because the NOx purification efficiency was slightly lower when the proportion of Rh contained in the lower layer 20 is 100% by mass, in other words, when the upper layer 21 was free of Rh. The proportion of Rh contained in the upper layer 21 is preferably at least 1% by mass based on the total amount of Rh in the catalyst coat layer 2.
  • Example 2 (Test Example 2) Using the catalysts of Example 1 and Comparative Example 1, after an endurance test was conducted in the same manner as in test example 1, the NO conversion rates at 300 0 C and 400 0 C were measured using a model gas containing NO and having an air-fuel ratio (A/F) equivalent to 20. The result is shown in FIG 3.
  • FIG 3 indicates that the catalyst of Comparative Example 1 had a lower NO conversion rate than the catalyst of Example 1, which means that the catalyst of Comparative Example had lower oxidation activity than the catalyst of Example 1. The reason for this is believed that the oxidation activity of Pt was inhibited by the formation of an alloy of Rh and Pt in the upper layer of the catalyst in Comparative Example 1.
  • Example 3 (Test Example 3) Using the catalysts of Example 4 and Comparative Example 1, after an endurance test was conducted in the same manner as in Test Example 1, the amount of hydrogen generated (the concentration of hydrogen in reaction gas) at 400 0 C was measured using a rich atmosphere model gas containing 0,1% of C 3 Hg and 4% of H 2 O. The result is shown in FIG 4.
  • FIG 3 indicates that the amount of hydrogen generated was smaller when the catalyst of Example 4 was used than when the catalyst of Comparative Example 1 was used. That is, when the upper layer 21 is free of Rh, the steam-reforming reaction is less likely to occur. Thus, it is apparent that Rh is preferably contained in the upper layer 20 as well.
  • the exhaust purification catalyst of this embodiment is primarily used in a straight flow structure NOx storage-reduction catalyst of an exhaust system for a gasoline engine, it may also be used for a filter catalyst, having a catalyst coat layer in the fine pores in cell walls, in the exhaust system of a diesel engine.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Catalysts (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

L'invention porte sur un catalyseur de purification de gaz de combustion. Le catalyseur comporte une couche de revêtement de catalyseur à structure bicouche comprenant une couche inférieure et une couche supérieure formée sur une surface de la couche inférieure. Au moins le platine ou le palladium est présent dans au moins la couche supérieure; 60 % en masse ou plus de la quantité totale de rhodium dans la couche de revêtement de catalyseur sont présents dans la couche inférieure.
PCT/IB2009/005749 2008-05-30 2009-05-28 Catalyseur de purification de gaz de combustion Ceased WO2009144568A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2008-142653 2008-05-30
JP2008142653A JP2009285604A (ja) 2008-05-30 2008-05-30 排ガス浄化用触媒

Publications (1)

Publication Number Publication Date
WO2009144568A1 true WO2009144568A1 (fr) 2009-12-03

Family

ID=40863731

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2009/005749 Ceased WO2009144568A1 (fr) 2008-05-30 2009-05-28 Catalyseur de purification de gaz de combustion

Country Status (2)

Country Link
JP (1) JP2009285604A (fr)
WO (1) WO2009144568A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9522385B2 (en) 2013-04-19 2016-12-20 Cataler Corporation Exhaust gas purifying catalyst
US9579633B2 (en) 2015-03-20 2017-02-28 Toyota Jidosha Kabushiki Kaisha Catalytic converter
US10143968B2 (en) 2014-12-12 2018-12-04 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying catalyst
US10556223B2 (en) 2014-12-12 2020-02-11 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying catalyst
US10576420B2 (en) 2014-12-12 2020-03-03 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying catalyst
US10634026B2 (en) 2016-02-10 2020-04-28 Toyota Jidosha Kabushiki Kaisha NOx storage reduction catalyst

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6996966B2 (ja) * 2017-12-26 2022-01-17 トヨタ自動車株式会社 排ガス浄化用触媒
JP7084190B2 (ja) * 2018-04-05 2022-06-14 トヨタ自動車株式会社 排ガス浄化用触媒
EP3795249A1 (fr) * 2018-05-17 2021-03-24 N.E. Chemcat Corporation Catalyseur de purification de gaz d'échappement et son procédé de production

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19742705A1 (de) * 1996-09-26 1998-04-02 Mazda Motor Abgasreinigungskatalysator
US20010006934A1 (en) * 1999-12-27 2001-07-05 Nissan Motor Co., Ltd. Catalytic converter with multilayered catalyst system
EP1174174A1 (fr) * 2000-07-18 2002-01-23 Daihatsu Motor Co., Ltd. Catalyseur pour la purification de gaz d'échappement
WO2005021138A2 (fr) * 2003-08-29 2005-03-10 Dow Global Technologies Inc. Filtre d'evacuation des diesels ameliore
JP2005279437A (ja) * 2004-03-29 2005-10-13 Toyota Motor Corp 排ガス浄化用触媒
JP2009101252A (ja) * 2007-10-19 2009-05-14 Toyota Motor Corp 排ガス浄化用触媒

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3296848B2 (ja) * 1992-07-24 2002-07-02 マツダ株式会社 排気ガス浄化用触媒及びその製造方法
JPH1199319A (ja) * 1997-07-28 1999-04-13 Petroleum Energy Center Found 排ガス浄化方法
JP3741303B2 (ja) * 1997-12-08 2006-02-01 トヨタ自動車株式会社 排ガス浄化用触媒
JP3861489B2 (ja) * 1998-01-30 2006-12-20 マツダ株式会社 排気ガス浄化用触媒及びその製造方法
JP2000054825A (ja) * 1998-08-07 2000-02-22 Nissan Motor Co Ltd 耐硫黄被毒性ＮＯｘ吸蔵材、これを用いた排ガス浄化触媒及び浄化システム
JP4786442B2 (ja) * 2006-07-10 2011-10-05 トヨタ自動車株式会社 ＮＯｘ吸蔵材の担持方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19742705A1 (de) * 1996-09-26 1998-04-02 Mazda Motor Abgasreinigungskatalysator
US20010006934A1 (en) * 1999-12-27 2001-07-05 Nissan Motor Co., Ltd. Catalytic converter with multilayered catalyst system
EP1174174A1 (fr) * 2000-07-18 2002-01-23 Daihatsu Motor Co., Ltd. Catalyseur pour la purification de gaz d'échappement
WO2005021138A2 (fr) * 2003-08-29 2005-03-10 Dow Global Technologies Inc. Filtre d'evacuation des diesels ameliore
JP2005279437A (ja) * 2004-03-29 2005-10-13 Toyota Motor Corp 排ガス浄化用触媒
JP2009101252A (ja) * 2007-10-19 2009-05-14 Toyota Motor Corp 排ガス浄化用触媒

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Week 200574, Derwent World Patents Index; AN 2005-717548 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9522385B2 (en) 2013-04-19 2016-12-20 Cataler Corporation Exhaust gas purifying catalyst
US10143968B2 (en) 2014-12-12 2018-12-04 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying catalyst
US10556223B2 (en) 2014-12-12 2020-02-11 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying catalyst
US10576420B2 (en) 2014-12-12 2020-03-03 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying catalyst
US9579633B2 (en) 2015-03-20 2017-02-28 Toyota Jidosha Kabushiki Kaisha Catalytic converter
US10634026B2 (en) 2016-02-10 2020-04-28 Toyota Jidosha Kabushiki Kaisha NOx storage reduction catalyst

Also Published As

Publication number Publication date
JP2009285604A (ja) 2009-12-10

Similar Documents

Publication Publication Date Title
EP0852966B1 (fr) Catalyseur et méthode pour la purification de gaz d'échappement
JP3724708B2 (ja) 排気ガス浄化用触媒
US5814576A (en) Catalyst for purifying exhaust gas and method of producing same
KR100196245B1 (ko) 배기가스 정화용 촉매
CN102083530B (zh) 用于净化汽车所排放废气的蜂窝结构型催化剂，其制备方法及使用该催化剂净化废气的方法
US6729125B2 (en) Exhaust gas purifying system
WO2009144568A1 (fr) Catalyseur de purification de gaz de combustion
EP1188908B1 (fr) Système de purification de gaz d'échappement
JP4228278B2 (ja) 排ガス浄化用触媒
WO2000000283A1 (fr) Catalyseur pour la purification des gaz d'echappement, procede de production dudit catalyseur et procede de purification de gaz d'echappement
WO2007145152A1 (fr) Catalyseur pour la purification d'un gaz d'échappement
JP3965676B2 (ja) 排ガス浄化用触媒及び排ガス浄化システム
JP2009273986A (ja) 排ガス浄化用触媒
JP2012055842A (ja) 排ガス浄化用触媒
JP4573993B2 (ja) 排気ガス浄化用触媒及びその製造方法
WO2009028721A2 (fr) Catalyseur de purification de gaz d'échappement
JP3589383B2 (ja) 排ガス浄化用触媒
JP2009248057A (ja) 排ガス浄化用触媒
JP5328133B2 (ja) 排ガス浄化用触媒
EP1080783A2 (fr) Catalyseur multi-couches pour l'épuration des gaz d'échappement
JP4980987B2 (ja) 排ガス浄化用触媒
JP3741297B2 (ja) 排ガス浄化用触媒
US20070123418A1 (en) Catalyst composition containing gallium for purifying exhaust gases of internal combustion engine
JP4019351B2 (ja) ＮＯｘ浄化触媒及びＮＯｘ浄化システム
JP2006043637A (ja) 排ガス浄化用触媒

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09754196

Country of ref document: EP

Kind code of ref document: A1

DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 09754196

Country of ref document: EP

Kind code of ref document: A1