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WO2014050630A1 - Exhaust gas purifying catalyst - Google Patents

Exhaust gas purifying catalyst Download PDF

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Publication number
WO2014050630A1
WO2014050630A1 PCT/JP2013/074999 JP2013074999W WO2014050630A1 WO 2014050630 A1 WO2014050630 A1 WO 2014050630A1 JP 2013074999 W JP2013074999 W JP 2013074999W WO 2014050630 A1 WO2014050630 A1 WO 2014050630A1
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WIPO (PCT)
Prior art keywords
exhaust gas
content
palladium
copper
mass
Prior art date
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PCT/JP2013/074999
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French (fr)
Japanese (ja)
Inventor
裕司 堤
千尋 松田
一哉 内藤
谷口　昌司
上西　真里
田中　裕久
Original Assignee
ダイハツ工業株式会社
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Priority claimed from JP2013017522A external-priority patent/JP2014147877A/en
Priority claimed from JP2013148789A external-priority patent/JP2014079749A/en
Application filed by ダイハツ工業株式会社 filed Critical ダイハツ工業株式会社
Publication of WO2014050630A1 publication Critical patent/WO2014050630A1/en

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    • 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
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8926—Copper and noble metals
    • 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]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • 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
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20761—Copper
    • 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 gas purification catalyst, and more particularly to an exhaust gas purification catalyst for purifying exhaust gas discharged from an internal combustion engine or the like.
  • Exhaust gas discharged from an internal combustion engine such as an automobile contains hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), etc., and an exhaust gas purifying catalyst for purifying them. It has been known.
  • noble metal elements Rh (rhodium), Pd (palladium), Pt (platinum), etc.
  • Rh rhodium
  • Pd palladium
  • Pt platinum
  • Various exhaust gas purifying catalysts are known which are supported or dissolved in a heat-resistant oxide such as alumina.
  • a simple metal catalyst for exhaust gas purification obtained by supporting a catalyst component such as Pt, Pd, Rh on an activated alumina layer covering a metal base material has been proposed (for example, Patent Documents). 1).
  • transition metals such as copper instead of noble metals as exhaust gas purifying catalysts
  • copper is used as an alumina support
  • the molar ratio of copper atoms to aluminum atoms Cu /
  • an exhaust gas purifying catalyst obtained by supporting Al in an amount of 0.01 to 0.1 (see, for example, Patent Document 2).
  • Patent Document 2 According to the exhaust gas purifying catalyst using copper or the like instead of the noble metal, the cost can be reduced. However, there is a problem that the exhaust gas purification performance is inferior.
  • an exhaust gas purification catalyst it may be required to improve the purification rate of HC, CO and NOx, particularly the purification rate of CO and NOx.
  • An object of the present invention is to provide an exhaust gas purification catalyst capable of reducing the amount of noble metal used and exhibiting superior gas purification performance.
  • the exhaust gas purifying catalyst of the present invention has palladium and copper and / or an alloy thereof supported on a heat-resistant oxide, and the content of copper is the content of palladium. And the palladium content is 0.2% by mass or less based on the total amount of the heat-resistant oxide, palladium and copper.
  • the mass ratio of the copper content to the palladium content (Cu / Pd) is 30 or more.
  • the exhaust gas purifying catalyst of the present invention is an exhaust gas purifying catalyst in which palladium and copper and / or an alloy thereof is supported on a heat-resistant oxide, and the copper content is larger than the palladium content, And the content rate of palladium is 0.2 mass% or less with respect to the total amount of a heat resistant oxide, palladium, and copper. Therefore, according to the exhaust gas purifying catalyst of the present invention, the amount of noble metal used can be reduced, the cost can be reduced, and exhaust gas, especially CO and NOx can be efficiently purified.
  • FIG. 1 is a graph showing the exhaust gas purification rates of Example 1 and Comparative Examples 1 and 2.
  • FIG. 2 is a graph showing the exhaust gas purification rates of Examples 2 to 3 and Comparative Example 3.
  • FIG. 3 is a graph showing the exhaust gas purification rates of Comparative Examples 4 to 5.
  • palladium (Pd) and copper (Cu) and / or alloys thereof are supported on the heat-resistant oxide.
  • the heat-resistant oxide is not particularly limited, and examples thereof include zirconia oxide, ceria oxide, perovskite complex oxide, and alumina.
  • zirconia-based oxide examples include zirconium dioxide (ZrO 2 ) and, for example, a zirconia-based composite oxide represented by the following general formula (1).
  • R represents a rare earth element (excluding Ce) and / or alkaline earth metal
  • a represents the atomic ratio of Ce
  • b represents the atomic ratio of R
  • 1- ( a + b) indicates the atomic ratio of Zr
  • c indicates the amount of oxygen defects.
  • examples of the rare earth element represented by R include Sc (scandium), Y (yttrium), La (lanthanum), Pr (praseodymium), Nd (neodymium), Pm (promethium), and Sm (promethium).
  • examples of the alkaline earth metal represented by R include Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium), and Ra (radium).
  • rare earth elements and alkaline earth metals can be used alone or in combination of two or more.
  • the atomic ratio of Ce represented by a is in the range of 0.1 to 0.65, and preferably in the range of 0.1 to 0.5.
  • the atomic ratio of R represented by b is in the range of 0 to 0.55 (that is, R is an optional component that is optionally included rather than an essential component, and if included, 0.55 or less) Atomic ratio). If it exceeds 0.55, phase separation or other complex oxide phases may be generated.
  • the atomic ratio of Zr represented by 1- (a + b) is in the range of 0.35 to 0.9, and preferably in the range of 0.5 to 0.9.
  • c represents the amount of oxygen defects, which means the ratio of vacancies formed in the crystal lattice in the fluorite-type crystal lattice usually formed by the oxides of Zr, Ce and R.
  • Such a zirconia-based composite oxide is not particularly limited, and for example, for preparing a composite oxide in accordance with the description of paragraph numbers [0090] to [0102] of JP-A-2004-243305. It can be produced by an appropriate method, for example, a production method such as a coprecipitation method, a citric acid complex method, or an alkoxide method.
  • ceria-based oxide examples include cerium oxide (CeO 2 ) and, for example, a ceria-based complex oxide represented by the following general formula (2).
  • the rare earth element represented by L includes the rare earth element represented by the general formula (1) (excluding Ce).
  • the alkaline-earth metal shown by L the alkaline-earth metal shown by General formula (1) is mentioned.
  • the atomic ratio of Zr represented by d is in the range of 0.2 to 0.7, preferably in the range of 0.2 to 0.5.
  • the atomic ratio of L represented by e is in the range of 0 to 0.2 (that is, L is an optional component that is not an essential component but is optionally included. Atomic ratio). If it exceeds 0.2, phase separation or other complex oxide phases may be generated.
  • the atomic ratio of Ce represented by 1- (d + e) is in the range of 0.3 to 0.8, and preferably in the range of 0.4 to 0.6.
  • the Ce atomic ratio represented by 1- (d + e) is preferably larger than the Ce atomic ratio represented by a in the general formula (1).
  • f represents the amount of oxygen defects, which means the ratio of vacancies formed in the crystal lattice in the fluorite-type crystal lattice that is normally formed by Ce, Zr and L oxides.
  • Such a ceria-based composite oxide can be manufactured by a manufacturing method similar to the above-described manufacturing method of the zirconia-based composite oxide.
  • the overlapping zirconia-based composite oxide is a ceria-based composite oxide. It belongs to a thing.
  • the perovskite complex oxide is represented by the following general formula (3).
  • ABO 3 (3) (In the formula, A represents at least one element selected from rare earth elements and alkaline earth metals, and B represents at least one element selected from transition elements excluding noble metals and Al.)
  • the rare earth element represented by A includes the rare earth element represented by the general formula (1) and Ce.
  • the alkaline-earth metal shown by A the alkaline-earth metal shown by General formula (1) is mentioned.
  • the transition element excluding the noble metal represented by B and Al for example, in the periodic table (IUPAC, 1990), atomic number 21 (Sc) to atomic number 30 (Zn), atomic number 39 (Y) to atomic number 48 (Cd) and atomic number 57 (La) to atomic number 80 (Hg) (except for noble metals (atomic numbers 44 to 47 and 76 to 78)), Al
  • Ti titanium
  • Cr chromium
  • Mn manganese
  • Fe iron
  • Co cobalt
  • Ni nickel
  • Cu copper
  • Zn (zinc) and Al (aluminum) aluminum
  • Such a perovskite-type composite oxide is not particularly limited, and for example, for preparing a composite oxide according to the description in paragraph numbers [0039] to [0059] of JP-A-2004-243305. It can be produced by an appropriate method, for example, a production method such as a coprecipitation method, a citric acid complex method, or an alkoxide method.
  • Examples of alumina include ⁇ -alumina, ⁇ -alumina, and ⁇ -alumina, and preferably ⁇ -alumina.
  • ⁇ -alumina has an ⁇ -phase as a crystal phase, and examples thereof include AKP-53 (trade name, high-purity alumina, manufactured by Sumitomo Chemical Co., Ltd.).
  • AKP-53 trade name, high-purity alumina, manufactured by Sumitomo Chemical Co., Ltd.
  • Such ⁇ -alumina can be obtained by a method such as an alkoxide method, a sol-gel method, or a coprecipitation method.
  • ⁇ -alumina is a kind of intermediate (transition) alumina that has a ⁇ -phase as a crystal phase and transitions to ⁇ -alumina, and includes, for example, SPHERALITE 531P (trade name, ⁇ -alumina, manufactured by Procatalyze). .
  • SPHERALITE 531P trade name, ⁇ -alumina, manufactured by Procatalyze
  • ⁇ -alumina can be obtained, for example, by heat-treating commercially available activated alumina ( ⁇ -alumina) at 900-1100 ° C. for 1-10 hours in the air.
  • ⁇ -alumina has a ⁇ -phase as a crystal phase and is not particularly limited, and examples thereof include known ones used for exhaust gas purification catalysts.
  • alumina containing La and / or Ba in these aluminas can be used.
  • Alumina containing La and / or Ba can be produced according to the description in paragraph No. [0073] of JP-A-2004-243305.
  • These heat-resistant oxides can be used alone or in combination of two or more.
  • the content ratio of palladium is, for example, 0.001% by mass or more, preferably 0.003% by mass or more, with respect to the total amount of the heat-resistant oxide, palladium and copper, and 0.2% % By mass or less, preferably 0.15% by mass or less, and more preferably 0.05% by mass or less.
  • the content ratio of palladium is not less than the above lower limit, excellent exhaust gas purification properties can be exhibited. If the palladium content is less than or equal to the above upper limit, the amount of noble metal used can be reduced, the cost can be reduced, and exhaust gas, especially CO and NOx can be efficiently purified.
  • the exhaust gas purification performance may be inferior, and if the palladium content exceeds the above upper limit, a synergistic effect of palladium and copper is exhibited. It cannot be made, and it is inferior to exhaust gas purification property.
  • the copper content is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, for example, 10.0% by mass with respect to the total amount of the heat-resistant oxide, palladium and copper. Hereinafter, it is preferably 1.8% by mass or less.
  • the copper content is adjusted to be larger than the palladium content.
  • the mass ratio of the copper content to the palladium content is, for example, 30 or more, preferably 35 or more, more preferably 40 or more.
  • the mass ratio of the copper content to the palladium content is, for example, 30 or more, preferably 35 or more, more preferably 40 or more.
  • it is 500 or less, preferably 300 or less, and more preferably 200 or less.
  • the mass ratio of the copper content to the palladium content (Cu / Pd) is not less than the above lower limit, excellent exhaust gas purification properties can be exhibited. If the mass ratio of the copper content to the palladium content (Cu / Pd) is equal to or less than the above upper limit, the amount of noble metal used is reduced, the cost is reduced, and exhaust gas, especially CO and NOx is efficiently used. Can be well purified.
  • a heat-resistant oxide supporting palladium and a heat-resistant oxide supporting copper are prepared.
  • a heat-resistant oxide carrying palladium is manufactured by, for example, carrying palladium on the above-mentioned heat-resistant oxide in accordance with the description in paragraphs [0122] to [0127] of JP-A-2004-243305. can do.
  • Preferred examples of the heat-resistant oxide for supporting palladium include ceria-based oxides and alumina.
  • the content ratio (supported amount) of palladium is, for example, 0.001% by mass or more, preferably 0.003% by mass or more with respect to the heat-resistant oxide. 0.2 mass% or less, preferably 0.15 mass% or less.
  • the heat-resistant oxide supporting copper is produced by, for example, supporting copper on the above-mentioned heat-resistant oxide in accordance with the description in paragraphs [0122] to [0127] of JP-A-2004-243305. can do.
  • alumina As a heat-resistant oxide for supporting copper, preferably, alumina is used.
  • the content ratio (supported amount) of copper is, for example, 0.1% by mass or more, preferably 0.5% by mass or more with respect to the heat-resistant oxide. It is 10.0 mass% or less, Preferably, it is 1.8 mass% or less.
  • the mixing method is not particularly limited, and examples thereof include known physical mixing methods such as dry mixing and wet mixing.
  • the heat-resistant oxide supporting palladium is, for example, 20 parts by mass or more with respect to 100 parts by mass of the total amount of the heat-resistant oxide supporting palladium and the heat-resistant oxide supporting copper. Preferably, it is 30 parts by mass or more, for example, 80 parts by mass or less, preferably 60 parts by mass or less.
  • supports copper is 20 mass parts or more, for example, Preferably, it is 40 mass parts or more, for example, 80 mass parts or less, Preferably, it is 70 mass parts or less.
  • heat-resistant oxide supporting palladium and copper is heat-treated in a reducing atmosphere (for example, a hydrogen-nitrogen mixed gas atmosphere), so that all or a part of copper and palladium is treated.
  • a reducing atmosphere for example, a hydrogen-nitrogen mixed gas atmosphere
  • the heating temperature is, for example, 500 ° C. or higher, preferably 600 ° C. or higher, for example, 1000 ° C. or lower, preferably 900 ° C. or lower.
  • the heating time is, for example, 0.5 hours or more, preferably 1.0 hours or more, for example, 10.0 hours or less, preferably 5.0 hours or less.
  • palladium and copper can be alloyed on the heat-resistant oxide, and the exhaust gas can be used as a heat-resistant oxide carrying palladium and a copper alloy (and, in some cases, unalloyed palladium and / or copper).
  • a purification catalyst can be obtained.
  • palladium and copper are alloyed by using a heat-resistant oxide supporting palladium and copper as a catalyst for exhaust gas purification and exposing to high-temperature exhaust gas. You can also
  • the method for obtaining the exhaust gas purification catalyst is not limited to the above.
  • the exhaust gas purification catalyst can be obtained by supporting palladium and copper simultaneously or sequentially on the same heat-resistant oxide, Furthermore, an exhaust gas purifying catalyst can be obtained by heat treatment and alloying if necessary.
  • a palladium and copper alloy produced in advance can be directly supported on a heat-resistant oxide in accordance with the above-described method to obtain an exhaust gas purification catalyst.
  • the exhaust gas purifying catalyst is not particularly limited, and may be used, for example, as the above powder.
  • the exhaust gas purifying catalyst may be formed into an arbitrary predetermined shape by a known method.
  • the exhaust gas purifying catalyst of the present invention can be used as a catalyst as it is, but is usually prepared as a catalyst compound by a known method such as loading on a catalyst carrier.
  • the catalyst carrier examples include known catalyst carriers such as a honeycomb monolith carrier made of cordierite.
  • the catalyst carrier For carrying on the catalyst carrier, for example, first, water or the like is added to the exhaust gas purifying catalyst obtained above to form a slurry. Then, this is coated on a catalyst carrier, dried, and then heat-treated at 300 to 800 ° C., preferably 300 to 600 ° C.
  • the exhaust gas purifying catalyst of the present invention can be supported on the catalyst carrier.
  • the exhaust gas purifying catalyst of the present invention is an exhaust gas purifying catalyst in which palladium and copper and / or an alloy thereof is supported on a heat-resistant oxide, wherein the copper content is higher than the palladium content.
  • the content ratio of palladium is 0.2% by mass or less with respect to the total amount of the heat-resistant oxide, palladium and copper. Therefore, according to the exhaust gas purifying catalyst of the present invention, the amount of noble metal used can be reduced, the cost can be reduced, and exhaust gas, especially CO and NOx can be efficiently purified.
  • the Ce content was 33.7% by mass in terms of CeO 2
  • the Zr content was 48.3% by mass in terms of ZrO 2
  • the La content was La 2
  • the content of Y was 10.6% by mass in terms of O 3 and the content of Y was 7.4% by mass in terms of Y 2 O 3 .
  • the Pd content ratio of this powder was 0.1% by mass with respect to the total amount of the Pd-supported ceria-based composite oxide.
  • Production Example 2 (Production of Cu / ⁇ -Al 2 O 3 (1)) ⁇ alumina was impregnated with an aqueous copper nitrate solution, dried, and then heat treated (fired) at 600 ° C. for 3 hours in an electric furnace to obtain Cu-supported ⁇ alumina (1) powder.
  • the Cu content ratio of this powder was 3.0% by mass with respect to the total amount of Cu-supported ⁇ -alumina (1).
  • Example 1 0.3 g of Pd-supported ceria-based composite oxide (Pd support ratio: 0.1% by mass) obtained in Production Example 1 and Cu support ⁇ -alumina (1) obtained in Production Example 2 (Cu support ratio: 3) 0.0 mass%) 0.4 g was mixed with a mortar to obtain an exhaust gas-purifying catalyst as a mixed powder.
  • Table 1 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
  • Comparative Example 1 An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that 0.3 g of ⁇ alumina (non-supported Pd and Cu) was used instead of 0.3 g of Pd-supported ceria-based composite oxide.
  • Table 1 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
  • Comparative Example 2 An exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that 0.4 g of ⁇ alumina (non-supported Pd and Cu) was used instead of 0.4 g of Cu supported ⁇ alumina (1).
  • Table 1 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
  • Test pieces were prepared by molding 0.5 g of the powders of Example 1 and Comparative Examples 1 and 2 into pellets having a size of 0.5 to 1.0 mm.
  • Production Example 3 (Production of Pd / ⁇ -Al 2 O 3 (1)) ⁇ alumina was impregnated with an aqueous palladium nitrate solution, dried, and then heat-treated (fired) at 600 ° C. for 3 hours in an electric furnace to obtain Pd-supported ⁇ -alumina (1) powder.
  • the Pd content ratio of this powder was 0.01% by mass relative to the total amount of Pd-supported ⁇ -alumina (1).
  • Production Example 4 (Production of Cu / ⁇ -Al 2 O 3 (2)) Cu-supported ⁇ -alumina (2) powder was obtained in the same manner as in Production Example 2, except that the amount of copper nitrate aqueous solution impregnated into ⁇ -alumina was changed.
  • the Cu content ratio of this powder was 1.0% by mass with respect to the total amount of Cu-supported ⁇ -alumina (2).
  • Example 2 0.5 g of Pd-supported ⁇ -alumina (1) (Pd support ratio: 0.01% by mass) obtained in Production Example 3 and Cu-supported ⁇ -alumina (2) obtained in Production Example 4 (Cu support ratio: 1) 0.0 mass%) and 0.5 g were mixed with a mortar to obtain an exhaust gas-purifying catalyst as a mixed powder.
  • Table 3 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
  • Example 3 0.5 g of Pd-supported ⁇ -alumina (1) (Pd support ratio: 0.01% by mass) obtained in Production Example 3 and Cu-supported ⁇ -alumina (2) obtained in Production Example 4 (Cu support ratio: 1) 0.0 mass%) 1.0 g was used in the same manner as in Example 2 to obtain an exhaust gas purification catalyst.
  • Table 3 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
  • Table 3 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
  • Test pieces were prepared by molding 0.5 g of the powders of Examples 2 to 3 and Comparative Example 3 into pellets having a size of 0.5 to 1.0 mm.
  • Production Example 5 (Production of Pd / Al 2 O 3 (2)) Pd-supported ⁇ -alumina (2) powder was obtained in the same manner as in Production Example 3, except that the amount of palladium nitrate aqueous solution impregnated into ⁇ -alumina was changed.
  • the Pd content ratio of this powder was 0.5% by mass with respect to the total amount of Pd-supported ⁇ -alumina (2).
  • Example 4 ⁇ alumina was impregnated with an aqueous palladium nitrate solution and an aqueous copper nitrate solution, dried, and then heat treated (fired) at 600 ° C. for 3 hours in an electric furnace to obtain Pd and Cu-supported ⁇ alumina powder.
  • Table 4 shows the Pd content, Cu content, and mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas-purifying catalyst.
  • Comparative Example 4 0.25 g of Pd-supported ⁇ -alumina obtained in Production Example 5 (Pd-supported proportion: 0.5% by mass) and Cu-supported ⁇ -alumina obtained in Production Example 2 (Cu-supported proportion: 3.0% by mass) 0 .25 g was mixed with a mortar to obtain a catalyst for exhaust gas purification as a mixed powder.
  • Table 4 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
  • Table 4 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
  • Test pieces were prepared by molding 0.5 g of the powders of Example 4 and Comparative Examples 4 and 5 into pellets having a size of 0.5 to 1.0 mm.

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Abstract

To provide an exhaust gas purifying catalyst which is capable of exhibiting more excellent gas purification performance, while reducing the amount of a noble metal used therein. An exhaust gas purifying catalyst wherein: a heat-resistant oxide is loaded with palladium and copper and/or an alloy of palladium and copper; the copper content is set larger than the palladium content; and the ratio of the palladium content is set to 0.2% by mass or less relative to the total amount of the heat-resistant oxide, palladium and copper. This exhaust gas purifying catalyst is able to decrease the cost by reducing the amount of a noble metal used therein, while efficiently purifying an exhaust gas, in particular, efficiently removing CO and NOx.

Description

排ガス浄化用触媒Exhaust gas purification catalyst
　本発明は、排ガス浄化用触媒、詳しくは、内燃機関などから排出される排気ガスを浄化するための排ガス用浄化触媒に関する。 The present invention relates to an exhaust gas purification catalyst, and more particularly to an exhaust gas purification catalyst for purifying exhaust gas discharged from an internal combustion engine or the like.
　自動車などの内燃機関から排出される排気ガスには、炭化水素（ＨＣ）、一酸化炭素（ＣＯ）、窒素酸化物（ＮＯｘ）などが含まれており、これらを浄化するための排ガス浄化用触媒が知られている。 Exhaust gas discharged from an internal combustion engine such as an automobile contains hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), etc., and an exhaust gas purifying catalyst for purifying them. It has been known.
　これらを浄化するための触媒として、活性成分である貴金属元素（Ｒｈ（ロジウム）、Ｐｄ（パラジウム）、Ｐｔ（白金）など）が、セリア系複合酸化物、ジルコニア系複合酸化物、ペロブスカイト複合酸化物またはアルミナなどの耐熱性酸化物に、担持または固溶している排ガス浄化用触媒が種々知られている。 As a catalyst for purifying these, noble metal elements (Rh (rhodium), Pd (palladium), Pt (platinum), etc.) which are active components are ceria-based complex oxides, zirconia-based complex oxides, perovskite complex oxides. Various exhaust gas purifying catalysts are known which are supported or dissolved in a heat-resistant oxide such as alumina.
　具体的には、例えば、メタル基材を被覆する活性アルミナ層に、Ｐｔ、Ｐｄ、Ｒｈなどの触媒成分を担持させて得られる排ガス浄化用メタル単体触媒が、提案されている（例えば、特許文献１参照。）。 Specifically, for example, a simple metal catalyst for exhaust gas purification obtained by supporting a catalyst component such as Pt, Pd, Rh on an activated alumina layer covering a metal base material has been proposed (for example, Patent Documents). 1).
　一方、排ガス浄化用触媒として、貴金属に代えて銅などの遷移金属を用いることも検討されており、具体的には、例えば、アルミナ担体に銅を、アルミニウム原子に対する銅原子のモル比（Ｃｕ／Ａｌ）が０．０１～０．１となるように担持させて得られる排ガス浄化用触媒が、提案されている（例えば、特許文献２参照。）。 On the other hand, the use of transition metals such as copper instead of noble metals as exhaust gas purifying catalysts has also been studied. Specifically, for example, copper is used as an alumina support, and the molar ratio of copper atoms to aluminum atoms (Cu / There has been proposed an exhaust gas purifying catalyst obtained by supporting Al) in an amount of 0.01 to 0.1 (see, for example, Patent Document 2).
特開昭６３－１６２０４５号公報JP 63-162045 A 特開平０５－３２９３６９号公報JP 05-329369 A
　しかるに、Ｐｔ、Ｐｄ、Ｒｈなどの貴金属は高価であるところ、特許文献１に記載されるような排ガス浄化用メタル単体触媒において、十分な排ガス浄化性能を発現させるためには、多くの貴金属を必要とし、コスト面に劣るという不具合がある。 However, noble metals such as Pt, Pd, and Rh are expensive, and in order to express sufficient exhaust gas purification performance in the exhaust gas purifying metal single catalyst as described in Patent Document 1, many noble metals are required. There is a problem that the cost is inferior.
　これに対して、特許文献２に記載されるように、貴金属に代えて銅などを用いた排ガス浄化用触媒によれば、低コスト化を図ることができる。しかし、排ガス浄化性能に劣るという不具合がある。 On the other hand, as described in Patent Document 2, according to the exhaust gas purifying catalyst using copper or the like instead of the noble metal, the cost can be reduced. However, there is a problem that the exhaust gas purification performance is inferior.
　また、このような排ガス浄化用触媒としては、ＨＣ、ＣＯおよびＮＯｘの浄化率、とりわけ、ＣＯおよびＮＯｘの浄化率の向上を図ることが要求される場合がある。 Further, as such an exhaust gas purification catalyst, it may be required to improve the purification rate of HC, CO and NOx, particularly the purification rate of CO and NOx.
　本発明の目的は、貴金属の使用量を低減するとともに、より優れたガス浄化性能を発現させることができる排ガス浄化用触媒を提供することにある。 An object of the present invention is to provide an exhaust gas purification catalyst capable of reducing the amount of noble metal used and exhibiting superior gas purification performance.
　上記目的を達成するために、本発明の排ガス浄化用触媒は、耐熱性酸化物に、パラジウムおよび銅、および／または、それらの合金が担持されており、銅の含有量が、パラジウムの含有量よりも多く、かつ、パラジウムの含有割合が、耐熱性酸化物、パラジウムおよび銅の総量に対して、０．２質量％以下であることを特徴としている。 In order to achieve the above object, the exhaust gas purifying catalyst of the present invention has palladium and copper and / or an alloy thereof supported on a heat-resistant oxide, and the content of copper is the content of palladium. And the palladium content is 0.2% by mass or less based on the total amount of the heat-resistant oxide, palladium and copper.
　また、本発明の排ガス浄化用触媒では、パラジウムの含有量に対する銅の含有量の質量比（Ｃｕ／Ｐｄ）が、３０以上であることが好適である。 In the exhaust gas purifying catalyst of the present invention, it is preferable that the mass ratio of the copper content to the palladium content (Cu / Pd) is 30 or more.
　本発明の排ガス浄化用触媒は、耐熱性酸化物に、パラジウムおよび銅、および／または、それらの合金が担持されている排ガス浄化用触媒において、銅の含有量がパラジウムの含有量よりも多く、かつ、パラジウムの含有割合が、耐熱性酸化物、パラジウムおよび銅の総量に対して、０．２質量％以下である。そのため、本発明の排ガス浄化用触媒によれば、貴金属の使用量を低減し、低コスト化を図るとともに、排ガス、とりわけ、ＣＯおよびＮＯｘを効率よく浄化することができる。 The exhaust gas purifying catalyst of the present invention is an exhaust gas purifying catalyst in which palladium and copper and / or an alloy thereof is supported on a heat-resistant oxide, and the copper content is larger than the palladium content, And the content rate of palladium is 0.2 mass% or less with respect to the total amount of a heat resistant oxide, palladium, and copper. Therefore, according to the exhaust gas purifying catalyst of the present invention, the amount of noble metal used can be reduced, the cost can be reduced, and exhaust gas, especially CO and NOx can be efficiently purified.
図１は、実施例１および比較例１～２の排ガス浄化率を示すグラフである。FIG. 1 is a graph showing the exhaust gas purification rates of Example 1 and Comparative Examples 1 and 2. 図２は、実施例２～３および比較例３の排ガス浄化率を示すグラフである。FIG. 2 is a graph showing the exhaust gas purification rates of Examples 2 to 3 and Comparative Example 3. 図３は、比較例４～５の排ガス浄化率を示すグラフである。FIG. 3 is a graph showing the exhaust gas purification rates of Comparative Examples 4 to 5.
　本発明の排ガス浄化用触媒では、耐熱性酸化物に、パラジウム（Ｐｄ）および銅（Ｃｕ）、および／または、それらの合金が担持されている。 In the exhaust gas purifying catalyst of the present invention, palladium (Pd) and copper (Cu) and / or alloys thereof are supported on the heat-resistant oxide.
　耐熱性酸化物としては、特に制限されないが、例えば、ジルコニア系酸化物、セリア系酸化物、ペロブスカイト型複合酸化物、アルミナなどが挙げられる。 The heat-resistant oxide is not particularly limited, and examples thereof include zirconia oxide, ceria oxide, perovskite complex oxide, and alumina.
　ジルコニア系酸化物としては、例えば、二酸化ジルコニウム（ＺｒＯ２）や、例えば、下記一般式（１）で示されるジルコニア系複合酸化物が挙げられる。 Examples of the zirconia-based oxide include zirconium dioxide (ZrO 2 ) and, for example, a zirconia-based composite oxide represented by the following general formula (1).
　　　　　　　　Ｚｒ１－（ａ＋ｂ）ＣｅａＲｂＯ２－ｃ　（１）
（式中、Ｒは、希土類元素（ただし、Ｃｅを除く。）および／またはアルカリ土類金属を示し、ａは、Ｃｅの原子割合を示し、ｂは、Ｒの原子割合を示し、１－（ａ＋ｂ）は、Ｚｒの原子割合を示し、ｃは、酸素欠陥量を示す。）
　一般式（１）において、Ｒで示される希土類元素としては、例えば、Ｓｃ（スカンジウム）、Ｙ（イットリウム）、Ｌａ（ランタン）、Ｐｒ（プラセオジム）、Ｎｄ（ネオジム）、Ｐｍ（プロメチウム）、Ｓｍ（サマリウム）、Ｅｕ（ユーロピウム）、Ｇｄ（ガドリニウム）、Ｔｂ（テルビウム）、Ｄｙ（ジスプロシウム）、Ｈｏ（ホルミウム）、Ｅｒ（エルビウム）、Ｔｍ（ツリウム）、Ｙｂ（イッテルビウム）、Ｌｕ（ルテチウム）などが挙げられる。 Zr 1- (a + b) Ce a RbO 2 -c (1)
(Wherein R represents a rare earth element (excluding Ce) and / or alkaline earth metal, a represents the atomic ratio of Ce, b represents the atomic ratio of R, and 1- ( a + b) indicates the atomic ratio of Zr, and c indicates the amount of oxygen defects.)
In the general formula (1), examples of the rare earth element represented by R include Sc (scandium), Y (yttrium), La (lanthanum), Pr (praseodymium), Nd (neodymium), Pm (promethium), and Sm (promethium). Samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium) and the like It is done.
　また、Ｒで示されるアルカリ土類金属としては、例えば、Ｂｅ（ベリリウム）、Ｍｇ（マグネシウム）、Ｃａ（カルシウム）、Ｓｒ（ストロンチウム）、Ｂａ（バリウム）、Ｒａ（ラジウム）などが挙げられる。 Further, examples of the alkaline earth metal represented by R include Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium), and Ra (radium).
　これら希土類元素およびアルカリ土類金属は、単独使用または２種以上併用することができる。 These rare earth elements and alkaline earth metals can be used alone or in combination of two or more.
　また、ａで示されるＣｅの原子割合は、０．１～０．６５の範囲であり、好ましくは、０．１～０．５の範囲である。 The atomic ratio of Ce represented by a is in the range of 0.1 to 0.65, and preferably in the range of 0.1 to 0.5.
　また、ｂで示されるＲの原子割合は０～０．５５の範囲である（すなわち、Ｒは必須成分ではなく任意的に含まれる任意成分であり、含まれる場合には、０．５５以下の原子割合である）。０．５５を超えると、相分離や他の複合酸化物相を生成する場合がある。 In addition, the atomic ratio of R represented by b is in the range of 0 to 0.55 (that is, R is an optional component that is optionally included rather than an essential component, and if included, 0.55 or less) Atomic ratio). If it exceeds 0.55, phase separation or other complex oxide phases may be generated.
　また、１－（ａ＋ｂ）で示されるＺｒの原子割合は、０．３５～０．９の範囲であり、好ましくは、０．５～０．９の範囲である。 The atomic ratio of Zr represented by 1- (a + b) is in the range of 0.35 to 0.9, and preferably in the range of 0.5 to 0.9.
　さらに、ｃは酸素欠陥量を示し、これは、Ｚｒ、ＣｅおよびＲの酸化物が通常形成するホタル石型の結晶格子において、その結晶格子にできる空孔の割合を意味する。 Furthermore, c represents the amount of oxygen defects, which means the ratio of vacancies formed in the crystal lattice in the fluorite-type crystal lattice usually formed by the oxides of Zr, Ce and R.
　このようなジルコニア系複合酸化物は、特に制限されることなく、例えば、特開２００４－２４３３０５号の段落番号〔００９０〕～〔０１０２〕の記載に準拠して、複合酸化物を調製するための適宜の方法、例えば、共沈法、クエン酸錯体法、アルコキシド法などの製造方法によって、製造することができる。 Such a zirconia-based composite oxide is not particularly limited, and for example, for preparing a composite oxide in accordance with the description of paragraph numbers [0090] to [0102] of JP-A-2004-243305. It can be produced by an appropriate method, for example, a production method such as a coprecipitation method, a citric acid complex method, or an alkoxide method.
　セリア系酸化物としては、例えば、酸化セリウム（ＣｅＯ２）や、例えば、下記一般式（２）で表されるセリア系複合酸化物が挙げられる。 Examples of the ceria-based oxide include cerium oxide (CeO 2 ) and, for example, a ceria-based complex oxide represented by the following general formula (2).
　　　　　　　　Ｃｅ１－（ｄ＋ｅ）ＺｒｄＬｅＯ２－ｆ　（２）
（式中、Ｌは、希土類元素（ただし、Ｃｅを除く。）および／またはアルカリ土類金属を示し、ｄは、Ｚｒの原子割合を示し、ｅは、Ｌの原子割合を示し、１－（ｄ＋ｅ）は、Ｃｅの原子割合を示し、ｆは、酸素欠陥量を示す。）
　一般式（２）において、Ｌで示される希土類元素としては、一般式（１）で示した希土類元素が挙げられる（ただし、Ｃｅを除く。）。また、Ｌで示されるアルカリ土類金属としては、一般式（１）で示したアルカリ土類金属が挙げられる。これら希土類元素およびアルカリ土類金属は、単独使用または２種以上併用することができる。 Ce1- (d + e) Zr d L e O 2 -f (2)
(Wherein L represents a rare earth element (excluding Ce) and / or alkaline earth metal, d represents the atomic ratio of Zr, e represents the atomic ratio of L, and 1- ( d + e) indicates the atomic ratio of Ce, and f indicates the amount of oxygen defects.)
In the general formula (2), the rare earth element represented by L includes the rare earth element represented by the general formula (1) (excluding Ce). Moreover, as an alkaline-earth metal shown by L, the alkaline-earth metal shown by General formula (1) is mentioned. These rare earth elements and alkaline earth metals can be used alone or in combination of two or more.
　また、ｄで示されるＺｒの原子割合は、０．２～０．７の範囲であり、好ましくは、０．２～０．５の範囲である。 Further, the atomic ratio of Zr represented by d is in the range of 0.2 to 0.7, preferably in the range of 0.2 to 0.5.
　また、ｅで示されるＬの原子割合は０～０．２の範囲である（すなわち、Ｌは必須成分ではなく任意的に含まれる任意成分であり、含まれる場合には、０．２以下の原子割合である）。０．２を超えると、相分離や他の複合酸化物相を生成する場合がある。 In addition, the atomic ratio of L represented by e is in the range of 0 to 0.2 (that is, L is an optional component that is not an essential component but is optionally included. Atomic ratio). If it exceeds 0.2, phase separation or other complex oxide phases may be generated.
　また、１－（ｄ＋ｅ）で示されるＣｅの原子割合は、０．３～０．８の範囲であり、好ましくは、０．４～０．６の範囲である。また、１－（ｄ＋ｅ）で示されるＣｅの原子割合は、一般式（１）のａで示されるＣｅの原子割合よりも多いことが好適である。 The atomic ratio of Ce represented by 1- (d + e) is in the range of 0.3 to 0.8, and preferably in the range of 0.4 to 0.6. The Ce atomic ratio represented by 1- (d + e) is preferably larger than the Ce atomic ratio represented by a in the general formula (1).
　さらに、ｆは酸素欠陥量を示し、これは、Ｃｅ、ＺｒおよびＬの酸化物が通常形成するホタル石型の結晶格子において、その結晶格子にできる空孔の割合を意味する。 Furthermore, f represents the amount of oxygen defects, which means the ratio of vacancies formed in the crystal lattice in the fluorite-type crystal lattice that is normally formed by Ce, Zr and L oxides.
　このようなセリア系複合酸化物は、上記したジルコニア系複合酸化物の製造方法と同様の製造方法によって、製造することができる。 Such a ceria-based composite oxide can be manufactured by a manufacturing method similar to the above-described manufacturing method of the zirconia-based composite oxide.
　なお、セリア系複合酸化物のＣｅの原子割合が、上記ジルコニア系複合酸化物のＣｅの原子割合と重複する場合は、本発明においては、その重複するジルコニア系複合酸化物は、セリア系複合酸化物に属するものとする。 When the Ce atomic ratio of the ceria-based composite oxide overlaps with the Ce atomic ratio of the zirconia-based composite oxide, in the present invention, the overlapping zirconia-based composite oxide is a ceria-based composite oxide. It belongs to a thing.
　ペロブスカイト型複合酸化物は、下記一般式（３）で示される。 The perovskite complex oxide is represented by the following general formula (3).
　　　　　　　　ＡＢＯ３　（３）
（式中、Ａは、希土類元素およびアルカリ土類金属から選ばれる少なくとも１種の元素を示し、Ｂは、貴金属を除く遷移元素およびＡｌから選ばれる少なくとも１種の元素を示す。）
　一般式（３）において、Ａで示される希土類元素としては、一般式（１）で示した希土類元素およびＣｅが挙げられる。また、Ａで示されるアルカリ土類金属としては、一般式（１）で示したアルカリ土類金属が挙げられる。 ABO 3 (3)
(In the formula, A represents at least one element selected from rare earth elements and alkaline earth metals, and B represents at least one element selected from transition elements excluding noble metals and Al.)
In the general formula (3), the rare earth element represented by A includes the rare earth element represented by the general formula (1) and Ce. Moreover, as an alkaline-earth metal shown by A, the alkaline-earth metal shown by General formula (1) is mentioned.
　一般式（３）において、Ｂで示される貴金属を除く遷移元素およびＡｌとしては、例えば、周期律表（ＩＵＰＡＣ、１９９０年）において、原子番号２１（Ｓｃ）～原子番号３０（Ｚｎ）、原子番号３９（Ｙ）～原子番号４８（Ｃｄ）、および、原子番号５７（Ｌａ）～原子番号８０（Ｈｇ）の各元素（ただし、貴金属（原子番号４４～４７および７６～７８）を除く）、Ａｌが挙げられ、好ましくは、Ｔｉ（チタン）、Ｃｒ（クロム）、Ｍｎ（マンガン）、Ｆｅ（鉄）、Ｃｏ（コバルト）、Ｎｉ（ニッケル）、Ｃｕ（銅）、Ｚｎ（亜鉛）およびＡｌ（アルミニウム）が挙げられる。これらは、単独使用または２種以上併用することができる。 In the general formula (3), as the transition element excluding the noble metal represented by B and Al, for example, in the periodic table (IUPAC, 1990), atomic number 21 (Sc) to atomic number 30 (Zn), atomic number 39 (Y) to atomic number 48 (Cd) and atomic number 57 (La) to atomic number 80 (Hg) (except for noble metals (atomic numbers 44 to 47 and 76 to 78)), Al Preferably, Ti (titanium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper), Zn (zinc) and Al (aluminum) ). These can be used alone or in combination of two or more.
　このようなペロブスカイト型複合酸化物は、特に制限されることなく、例えば、特開２００４－２４３３０５号の段落番号〔００３９〕～〔００５９〕の記載に準拠して、複合酸化物を調製するための適宜の方法、例えば、共沈法、クエン酸錯体法、アルコキシド法などの製造方法によって、製造することができる。 Such a perovskite-type composite oxide is not particularly limited, and for example, for preparing a composite oxide according to the description in paragraph numbers [0039] to [0059] of JP-A-2004-243305. It can be produced by an appropriate method, for example, a production method such as a coprecipitation method, a citric acid complex method, or an alkoxide method.
　アルミナとしては、例えば、αアルミナ、θアルミナ、γアルミナなどが挙げられ、好ましくは、θアルミナが挙げられる。αアルミナは、結晶相としてα相を有し、例えば、ＡＫＰ－５３（商品名、高純度アルミナ、住友化学社製）などが挙げられる。このようなαアルミナは、例えば、アルコキシド法、ゾルゲル法、共沈法などの方法によって得ることができる。 Examples of alumina include α-alumina, θ-alumina, and γ-alumina, and preferably θ-alumina. α-alumina has an α-phase as a crystal phase, and examples thereof include AKP-53 (trade name, high-purity alumina, manufactured by Sumitomo Chemical Co., Ltd.). Such α-alumina can be obtained by a method such as an alkoxide method, a sol-gel method, or a coprecipitation method.
　θアルミナは、結晶相としてθ相を有し、αアルミナに遷移するまでの中間（遷移）アルミナの一種であって、例えば、ＳＰＨＥＲＡＬＩＴＥ　５３１Ｐ（商品名、γアルミナ、プロキャタリゼ社製）などが挙げられる。このようなθアルミナは、例えば、市販の活性アルミナ（γアルミナ）を、大気中にて、９００～１１００℃で、１～１０時間熱処理することによって得ることができる。　γアルミナは、結晶相としてγ相を有し、特に限定されず、例えば、排ガス浄化用触媒などに用いられている公知のものが挙げられる。 θ-alumina is a kind of intermediate (transition) alumina that has a θ-phase as a crystal phase and transitions to α-alumina, and includes, for example, SPHERALITE 531P (trade name, γ-alumina, manufactured by Procatalyze). . Such θ-alumina can be obtained, for example, by heat-treating commercially available activated alumina (γ-alumina) at 900-1100 ° C. for 1-10 hours in the air. Γ-alumina has a γ-phase as a crystal phase and is not particularly limited, and examples thereof include known ones used for exhaust gas purification catalysts.
　また、これらのアルミナにＬａおよび／またはＢａが含まれるアルミナを用いることもできる。Ｌａおよび／またはＢａを含むアルミナは、特開２００４－２４３３０５号の段落番号〔００７３〕の記載に準拠して、製造することができる。 Also, alumina containing La and / or Ba in these aluminas can be used. Alumina containing La and / or Ba can be produced according to the description in paragraph No. [0073] of JP-A-2004-243305.
　これら耐熱性酸化物は、単独使用または２種類以上併用することができる。 These heat-resistant oxides can be used alone or in combination of two or more.
　排ガス浄化用触媒において、パラジウムの含有割合は、耐熱性酸化物、パラジウムおよび銅の総量に対して、例えば、０．００１質量％以上、好ましくは、０．００３質量％以上であり、０．２質量％以下、好ましくは、０．１５質量％以下、さらに好ましくは、０．０５質量％以下である。 In the exhaust gas purification catalyst, the content ratio of palladium is, for example, 0.001% by mass or more, preferably 0.003% by mass or more, with respect to the total amount of the heat-resistant oxide, palladium and copper, and 0.2% % By mass or less, preferably 0.15% by mass or less, and more preferably 0.05% by mass or less.
　パラジウムの含有割合が上記下限以上であれば、優れた排ガス浄化性を発現することができる。また、パラジウムの含有割合が上記上限以下であれば、貴金属の使用量を低減し、低コスト化を図るとともに、排ガス、とりわけ、ＣＯおよびＮＯｘを効率よく浄化することができる。 If the content ratio of palladium is not less than the above lower limit, excellent exhaust gas purification properties can be exhibited. If the palladium content is less than or equal to the above upper limit, the amount of noble metal used can be reduced, the cost can be reduced, and exhaust gas, especially CO and NOx can be efficiently purified.
　一方、パラジウムの含有割合が上記下限未満である場合には、排ガス浄化性に劣る場合があり、また、パラジウムの含有割合が上記上限を超過する場合には、パラジウムと銅との相乗効果を発現させることができず、排ガス浄化性に劣る。 On the other hand, if the palladium content is less than the above lower limit, the exhaust gas purification performance may be inferior, and if the palladium content exceeds the above upper limit, a synergistic effect of palladium and copper is exhibited. It cannot be made, and it is inferior to exhaust gas purification property.
　また、銅の含有割合は、耐熱性酸化物、パラジウムおよび銅の総量に対して、例えば、０．１質量％以上、好ましくは、０．５質量％以上であり、例えば、１０．０質量％以下、好ましくは、１．８質量％以下である。 The copper content is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, for example, 10.0% by mass with respect to the total amount of the heat-resistant oxide, palladium and copper. Hereinafter, it is preferably 1.8% by mass or less.
　また、この排ガス浄化用触媒においては、銅の含有量が、パラジウムの含有量よりも多くなるように調整される。 Also, in this exhaust gas purifying catalyst, the copper content is adjusted to be larger than the palladium content.
　具体的には、この排ガス浄化用触媒において、パラジウムの含有量に対する銅の含有量の質量比（Ｃｕ／Ｐｄ）は、例えば、３０以上、好ましくは、３５以上、より好ましくは、４０以上であり、例えば、５００以下、好ましくは、３００以下、より好ましくは、２００以下である。 Specifically, in the exhaust gas-purifying catalyst, the mass ratio of the copper content to the palladium content (Cu / Pd) is, for example, 30 or more, preferably 35 or more, more preferably 40 or more. For example, it is 500 or less, preferably 300 or less, and more preferably 200 or less.
　パラジウムの含有量に対する銅の含有量の質量比（Ｃｕ／Ｐｄ）が上記下限以上であれば、優れた排ガス浄化性を発現することができる。またパラジウムの含有量に対する銅の含有量の質量比（Ｃｕ／Ｐｄ）が上記上限以下であれば、貴金属の使用量を低減し、低コスト化を図るとともに、排ガス、とりわけ、ＣＯおよびＮＯｘを効率よく浄化することができる。 If the mass ratio of the copper content to the palladium content (Cu / Pd) is not less than the above lower limit, excellent exhaust gas purification properties can be exhibited. If the mass ratio of the copper content to the palladium content (Cu / Pd) is equal to or less than the above upper limit, the amount of noble metal used is reduced, the cost is reduced, and exhaust gas, especially CO and NOx is efficiently used. Can be well purified.
　そして、排ガス浄化用触媒を得るには、例えば、まず、パラジウムを担持する耐熱性酸化物と、銅を担持する耐熱性酸化物とを用意する。 In order to obtain an exhaust gas purifying catalyst, for example, first, a heat-resistant oxide supporting palladium and a heat-resistant oxide supporting copper are prepared.
　パラジウムを担持する耐熱性酸化物は、例えば、特開２００４－２４３３０５号の段落番号〔０１２２〕～〔０１２７〕の記載に準拠して、上記の耐熱性酸化物にパラジウムを担持させることによって、製造することができる。 A heat-resistant oxide carrying palladium is manufactured by, for example, carrying palladium on the above-mentioned heat-resistant oxide in accordance with the description in paragraphs [0122] to [0127] of JP-A-2004-243305. can do.
　パラジウムを担持するための耐熱性酸化物として、好ましくは、セリア系酸化物、アルミナが挙げられる。 Preferred examples of the heat-resistant oxide for supporting palladium include ceria-based oxides and alumina.
　パラジウムを担持する耐熱性酸化物において、パラジウムの含有割合（担持量）は、耐熱性酸化物に対して、例えば、０．００１質量％以上、好ましくは、０．００３質量％以上であり、例えば、０．２質量％以下、好ましくは、０．１５質量％以下である。 In the heat-resistant oxide supporting palladium, the content ratio (supported amount) of palladium is, for example, 0.001% by mass or more, preferably 0.003% by mass or more with respect to the heat-resistant oxide. 0.2 mass% or less, preferably 0.15 mass% or less.
　銅を担持する耐熱性酸化物は、例えば、特開２００４－２４３３０５号の段落番号〔０１２２〕～〔０１２７〕の記載に準拠して、上記の耐熱性酸化物に銅を担持させることによって、製造することができる。 The heat-resistant oxide supporting copper is produced by, for example, supporting copper on the above-mentioned heat-resistant oxide in accordance with the description in paragraphs [0122] to [0127] of JP-A-2004-243305. can do.
　銅を担持するための耐熱性酸化物として、好ましくは、アルミナが挙げられる。 As a heat-resistant oxide for supporting copper, preferably, alumina is used.
　銅を担持する耐熱性酸化物において、銅の含有割合（担持量）は、耐熱性酸化物に対して、例えば、０．１質量％以上、好ましくは、０．５質量％以上であり、例えば、１０．０質量％以下、好ましくは、１．８質量％以下である。 In the heat-resistant oxide supporting copper, the content ratio (supported amount) of copper is, for example, 0.1% by mass or more, preferably 0.5% by mass or more with respect to the heat-resistant oxide. It is 10.0 mass% or less, Preferably, it is 1.8 mass% or less.
　次いで、この方法では、パラジウムを担持する耐熱性酸化物と、銅を担持する耐熱性酸化物とを混合する。 Next, in this method, a heat-resistant oxide supporting palladium and a heat-resistant oxide supporting copper are mixed.
　混合方法としては、特に制限されず、例えば、乾式混合、湿式混合などの公知の物理混合方法が挙げられる。 The mixing method is not particularly limited, and examples thereof include known physical mixing methods such as dry mixing and wet mixing.
　混合割合としては、パラジウムを担持する耐熱性酸化物と、銅を担持する耐熱性酸化物との総量１００質量部に対して、パラジウムを担持する耐熱性酸化物が、例えば、２０質量部以上、好ましくは、３０質量部以上であり、例えば、８０質量部以下、好ましくは、６０質量部以下である。また、銅を担持する耐熱性酸化物が、例えば、２０質量部以上、好ましくは、４０質量部以上であり、例えば、８０質量部以下、好ましくは、７０質量部以下である。 As a mixing ratio, the heat-resistant oxide supporting palladium is, for example, 20 parts by mass or more with respect to 100 parts by mass of the total amount of the heat-resistant oxide supporting palladium and the heat-resistant oxide supporting copper. Preferably, it is 30 parts by mass or more, for example, 80 parts by mass or less, preferably 60 parts by mass or less. Moreover, the heat resistant oxide which carry | supports copper is 20 mass parts or more, for example, Preferably, it is 40 mass parts or more, for example, 80 mass parts or less, Preferably, it is 70 mass parts or less.
　これにより、耐熱性酸化物にパラジウムおよび銅を担持させることができ、パラジウムおよび銅を担持する耐熱性酸化物として、排ガス浄化用触媒を得ることができる。 Thereby, palladium and copper can be supported on the heat-resistant oxide, and the exhaust gas-purifying catalyst can be obtained as the heat-resistant oxide supporting palladium and copper.
　また、この方法では、必要により、パラジウムおよび銅を担持する耐熱性酸化物を、還元雰囲気（例えば、水素－窒素混合ガス雰囲気など）下において熱処理することにより、銅およびパラジウムの全部または一部を合金化することができる。 In this method, if necessary, heat-resistant oxide supporting palladium and copper is heat-treated in a reducing atmosphere (for example, a hydrogen-nitrogen mixed gas atmosphere), so that all or a part of copper and palladium is treated. Can be alloyed.
　熱処理条件としては、加熱温度が、例えば、５００℃以上、好ましくは、６００℃以上であり、例えば、１０００℃以下、好ましくは、９００℃以下である。また、加熱時間が、例えば、０．５時間以上、好ましくは、１．０時間以上であり、例えば、１０．０時間以下、好ましくは、５．０時間以下である。 As the heat treatment conditions, the heating temperature is, for example, 500 ° C. or higher, preferably 600 ° C. or higher, for example, 1000 ° C. or lower, preferably 900 ° C. or lower. The heating time is, for example, 0.5 hours or more, preferably 1.0 hours or more, for example, 10.0 hours or less, preferably 5.0 hours or less.
　これにより、耐熱性酸化物上においてパラジウムおよび銅を合金化することができ、パラジウムおよび銅の合金（さらに、場合により合金化していないパラジウムおよび／または銅）を担持する耐熱性酸化物として、排ガス浄化用触媒を得ることができる。 As a result, palladium and copper can be alloyed on the heat-resistant oxide, and the exhaust gas can be used as a heat-resistant oxide carrying palladium and a copper alloy (and, in some cases, unalloyed palladium and / or copper). A purification catalyst can be obtained.
　また、例えば、上記のように還元雰囲気下において熱処理することなく、パラジウムおよび銅を担持する耐熱性酸化物を排ガス浄化用触媒として用い、高温の排ガスに曝露することにより、パラジウムおよび銅を合金化することもできる。 Also, for example, without heat treatment in a reducing atmosphere as described above, palladium and copper are alloyed by using a heat-resistant oxide supporting palladium and copper as a catalyst for exhaust gas purification and exposing to high-temperature exhaust gas. You can also
　なお、排ガス浄化用触媒を得る方法としては、上記に限定されず、例えば、パラジウムおよび銅を、同一の耐熱性酸化物に同時にまたは順次担持させることにより、排ガス浄化用触媒を得ることができ、さらに、必要により熱処理および合金化することにより、排ガス浄化用触媒を得ることができる。 The method for obtaining the exhaust gas purification catalyst is not limited to the above. For example, the exhaust gas purification catalyst can be obtained by supporting palladium and copper simultaneously or sequentially on the same heat-resistant oxide, Furthermore, an exhaust gas purifying catalyst can be obtained by heat treatment and alloying if necessary.
　また、例えば、予め製造されたパラジウムおよび銅の合金を、上記した方法に準じて耐熱性酸化物に直接担持させ、排ガス浄化用触媒を得ることもできる。 Also, for example, a palladium and copper alloy produced in advance can be directly supported on a heat-resistant oxide in accordance with the above-described method to obtain an exhaust gas purification catalyst.
　そして、排ガス浄化用触媒は、特に制限されず、例えば、上記の粉末として用いてもよく、例えば、公知の方法により、任意の所定形状に成形して用いてもよい。 The exhaust gas purifying catalyst is not particularly limited, and may be used, for example, as the above powder. For example, the exhaust gas purifying catalyst may be formed into an arbitrary predetermined shape by a known method.
　また、本発明の排ガス浄化用触媒は、そのまま、触媒として用いることもできるが、通常、触媒担体上に担持させるなど、公知の方法により、触媒化合物として調製される。 The exhaust gas purifying catalyst of the present invention can be used as a catalyst as it is, but is usually prepared as a catalyst compound by a known method such as loading on a catalyst carrier.
　触媒担体としては、例えば、コージェライトなどからなるハニカム状のモノリス担体など、公知の触媒担体が挙げられる。 Examples of the catalyst carrier include known catalyst carriers such as a honeycomb monolith carrier made of cordierite.
　触媒担体上に担持させるには、例えば、まず、上記により得られた排ガス浄化用触媒に、水などを加えてスラリーとする。そして、これを触媒担体上にコーティングし、乾燥させ、その後、３００～８００℃、好ましくは、３００～６００℃で熱処理する。 For carrying on the catalyst carrier, for example, first, water or the like is added to the exhaust gas purifying catalyst obtained above to form a slurry. Then, this is coated on a catalyst carrier, dried, and then heat-treated at 300 to 800 ° C., preferably 300 to 600 ° C.
　これにより、本発明の排ガス浄化用触媒を、触媒担体上に担持させることができる。 Thereby, the exhaust gas purifying catalyst of the present invention can be supported on the catalyst carrier.
　そして、本発明の排ガス浄化用触媒は、耐熱性酸化物に、パラジウムおよび銅、および／または、それらの合金が担持されている排ガス浄化用触媒において、銅の含有量がパラジウムの含有量よりも多く、かつ、パラジウムの含有割合が、耐熱性酸化物、パラジウムおよび銅の総量に対して、０．２質量％以下である。そのため、本発明の排ガス浄化用触媒によれば、貴金属の使用量を低減し、低コスト化を図るとともに、排ガス、とりわけ、ＣＯおよびＮＯｘを効率よく浄化することができる。 The exhaust gas purifying catalyst of the present invention is an exhaust gas purifying catalyst in which palladium and copper and / or an alloy thereof is supported on a heat-resistant oxide, wherein the copper content is higher than the palladium content. The content ratio of palladium is 0.2% by mass or less with respect to the total amount of the heat-resistant oxide, palladium and copper. Therefore, according to the exhaust gas purifying catalyst of the present invention, the amount of noble metal used can be reduced, the cost can be reduced, and exhaust gas, especially CO and NOx can be efficiently purified.
　次に、本発明を実施例および比較例に基づいて説明するが、本発明は下記の実施例によって限定されるものではない。 Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples.
　製造例１（Ｐｄ／Ｃｅ０．２７３Ｚｒ０．５４５Ｌａ０．０９１Ｙ０．０９１Ｏｘｉｄｅの製造）
　セリウムメトキシプロピレート［Ｃｅ（ＯＣＨ（ＣＨ３）ＣＨ２ＯＣＨ３）３］をＣｅ換算で０．０２７３ｍｏｌと、ジルコニウムメトキシプロピレート［Ｚｒ（ＯＣＨ（ＣＨ３）ＣＨ２ＯＣＨ３）３］をＺｒ換算で０．０５４５ｍｏｌと、ランタンメトキシプロピレート［Ｌａ（ＯＣＨ（ＣＨ３）ＣＨ２ＯＣＨ３）３］をＬａ換算で０．００９１ｍｏｌと、イットリウムメトキシプロピレート［Ｙ（ＯＣＨ（ＣＨ３）ＣＨ２ＯＣＨ３）３］をＹ換算で０．００９１ｍｏｌと、トルエン２００ｍＬとを配合して、撹拌溶解することにより、混合アルコキシド溶液を調製した。さらに、この混合アルコキシド溶液に、脱イオン水８０ｍＬを滴下して、加水分解した。 Production Example 1 (Production of Pd / Ce 0.273 Zr 0.545 La 0.091 Y 0.091 Oxide)
Cerium methoxypropyrate [Ce (OCH (CH 3 ) CH 2 OCH 3 ) 3 ] is converted into 0.0273 mol in terms of Ce and zirconium methoxypropylate [Zr (OCH (CH 3 ) CH 2 OCH 3 ) 3 ] is converted into Zr 0.0545 mol and 0.0091 mol of lanthanum methoxypropyrate [La (OCH (CH 3 ) CH 2 OCH 3 ) 3 ] in terms of La and yttrium methoxypropyrate [Y (OCH (CH 3 ) CH 2 OCH 3 3 ) was converted into Y in a proportion of 0.0091 mol and 200 mL of toluene, and dissolved by stirring to prepare a mixed alkoxide solution. Further, 80 mL of deionized water was added dropwise to the mixed alkoxide solution for hydrolysis.
　次いで、加水分解された溶液から、トルエンおよび脱イオン水を留去し、乾固させて、前駆体を得た。さらに、この前駆体を、６０℃で２４時間通風乾燥させた後、電気炉にて、４５０℃で３時間熱処理（焼成）することにより、Ｃｅ０．２７３Ｚｒ０．５４５Ｌａ０．０９１Ｙ０．０９１Ｏｘｉｄｅで示されるセリア系複合酸化物の粉末を得た。 Subsequently, toluene and deionized water were distilled off from the hydrolyzed solution and dried to obtain a precursor. Furthermore, this precursor was air-dried at 60 ° C. for 24 hours and then heat-treated (fired) at 450 ° C. for 3 hours in an electric furnace, whereby Ce 0.273 Zr 0.545 La 0.091 Y 0 A powder of ceria based oxide represented by 0.091 Oxide was obtained.
　得られたセリア系複合酸化物において、Ｃｅの含有量は、ＣｅＯ２換算で３３．７質量％、Ｚｒの含有量は、ＺｒＯ２換算で４８．３質量％、Ｌａの含有量は、Ｌａ２Ｏ３換算で１０．６質量％、Ｙの含有量は、Ｙ２Ｏ３換算で７．４質量％であった。 In the obtained ceria-based composite oxide, the Ce content was 33.7% by mass in terms of CeO 2 , the Zr content was 48.3% by mass in terms of ZrO 2 , and the La content was La 2 The content of Y was 10.6% by mass in terms of O 3 and the content of Y was 7.4% by mass in terms of Y 2 O 3 .
　その後、得られたセリア系複合酸化物に、硝酸パラジウム水溶液を加え、１時間攪拌混合して含浸させた。その後、８０℃で２４時間乾燥させ、６５０℃で１時間熱処理することにより、Ｐｄ担持セリア系複合酸化物の粉末を得た。 Thereafter, an aqueous palladium nitrate solution was added to the obtained ceria-based composite oxide, and the mixture was impregnated by stirring for 1 hour. Then, it was dried at 80 ° C. for 24 hours, and heat-treated at 650 ° C. for 1 hour to obtain a Pd-supported ceria-based composite oxide powder.
　この粉末のＰｄ含有割合は、Ｐｄ担持セリア系複合酸化物の総量に対して、０．１質量％であった。 The Pd content ratio of this powder was 0.1% by mass with respect to the total amount of the Pd-supported ceria-based composite oxide.
　　製造例２（Ｃｕ／θ－Ａｌ２Ｏ３（１）の製造）
　θアルミナに、硝酸銅水溶液を含浸させ、乾燥後、電気炉にて、６００℃で３時間熱処理（焼成）することにより、Ｃｕ担持θアルミナ（１）粉末を得た。 Production Example 2 (Production of Cu / θ-Al 2 O 3 (1))
θ alumina was impregnated with an aqueous copper nitrate solution, dried, and then heat treated (fired) at 600 ° C. for 3 hours in an electric furnace to obtain Cu-supported θ alumina (1) powder.
　この粉末のＣｕ含有割合は、Ｃｕ担持θアルミナ（１）の総量に対して、３．０質量％であった。 The Cu content ratio of this powder was 3.0% by mass with respect to the total amount of Cu-supported θ-alumina (1).
　　実施例１
　製造例１において得られたＰｄ担持セリア系複合酸化物（Ｐｄ担持割合：０．１質量％）０．３ｇと、製造例２において得られたＣｕ担持θアルミナ（１）（Ｃｕ担持割合：３．０質量％）０．４ｇとを、乳鉢により混合し、混合粉末として排ガス浄化用触媒を得た。 Example 1
0.3 g of Pd-supported ceria-based composite oxide (Pd support ratio: 0.1% by mass) obtained in Production Example 1 and Cu support θ-alumina (1) obtained in Production Example 2 (Cu support ratio: 3) 0.0 mass%) 0.4 g was mixed with a mortar to obtain an exhaust gas-purifying catalyst as a mixed powder.
　得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表１に示す。 Table 1 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
　　比較例１
　Ｐｄ担持セリア系複合酸化物０．３ｇに代えて、θアルミナ（ＰｄおよびＣｕ無担持物）０．３ｇを用いた以外は、実施例１と同様にして、排ガス浄化用触媒を得た。 Comparative Example 1
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that 0.3 g of θ alumina (non-supported Pd and Cu) was used instead of 0.3 g of Pd-supported ceria-based composite oxide.
　得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表１に示す。 Table 1 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
　　比較例２
　Ｃｕ担持θアルミナ（１）０．４ｇに代えて、θアルミナ（ＰｄおよびＣｕ無担持物）０．４ｇを用いた以外は、実施例１と同様にして、排ガス浄化用触媒を得た。 Comparative Example 2
An exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that 0.4 g of θ alumina (non-supported Pd and Cu) was used instead of 0.4 g of Cu supported θ alumina (1).
　得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表１に示す。 Table 1 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　評価（ＮＯｘおよびＣＯ浄化率）
　実施例１および比較例１～２の粉末０．５ｇを、０．５～１．０ｍｍのサイズのペレットに成型して試験片を調製した。 Evaluation (NOx and CO purification rate)
Test pieces were prepared by molding 0.5 g of the powders of Example 1 and Comparative Examples 1 and 2 into pellets having a size of 0.5 to 1.0 mm.
　表２に示す組成のモデルガスを用いて、このモデルガスの燃焼（空燃比Ａ／Ｆ＝１４．０）によって排出される排気ガス（温度：４００℃、流速：２．５Ｌ／ｍｉｎ）を各試験片に供給し、排ガス中のＮＯｘおよびＣＯの浄化率（４００℃浄化率：％）を測定した。 Using the model gas having the composition shown in Table 2, each exhaust gas (temperature: 400 ° C., flow rate: 2.5 L / min) discharged by combustion of this model gas (air-fuel ratio A / F = 14.0) It supplied to the test piece and measured the purification rate of NOx and CO in the exhaust gas (400 ° C. purification rate:%).
　その結果を、表１および図１に示す。 The results are shown in Table 1 and FIG.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
（考察）
　図１より、耐熱性酸化物にパラジウムおよび銅が担持されており、銅の含有量がパラジウムの含有量よりも多く、かつ、パラジウムの含有割合が０．２質量％以下である実施例１の排ガス浄化用触媒は、パラジウムまたは銅のみを担持する比較例１および２の排ガス浄化用触媒に比べ、排ガス浄化性に優れることが確認された。 (Discussion)
From FIG. 1, palladium and copper are supported on the heat-resistant oxide, the copper content is higher than the palladium content, and the palladium content is 0.2% by mass or less. It was confirmed that the exhaust gas purifying catalyst was superior in exhaust gas purifying properties as compared with the exhaust gas purifying catalysts of Comparative Examples 1 and 2 that supported only palladium or copper.
　　製造例３（Ｐｄ／θ－Ａｌ２Ｏ３（１）の製造）
　θアルミナに、硝酸パラジウム水溶液を含浸させ、乾燥後、電気炉にて、６００℃で３時間熱処理（焼成）することにより、Ｐｄ担持θアルミナ（１）の粉末を得た。 Production Example 3 (Production of Pd / θ-Al 2 O 3 (1))
θ alumina was impregnated with an aqueous palladium nitrate solution, dried, and then heat-treated (fired) at 600 ° C. for 3 hours in an electric furnace to obtain Pd-supported θ-alumina (1) powder.
　この粉末のＰｄ含有割合は、Ｐｄ担持θアルミナ（１）の総量に対して、０．０１質量％であった。 The Pd content ratio of this powder was 0.01% by mass relative to the total amount of Pd-supported θ-alumina (1).
　　製造例４（Ｃｕ／θ－Ａｌ２Ｏ３（２）の製造）
　θアルミナに対する硝酸銅水溶液の含浸量を変更した以外は、製造例２と同様にして、Ｃｕ担持θアルミナ（２）粉末を得た。 Production Example 4 (Production of Cu / θ-Al 2 O 3 (2))
Cu-supported θ-alumina (2) powder was obtained in the same manner as in Production Example 2, except that the amount of copper nitrate aqueous solution impregnated into θ-alumina was changed.
　この粉末のＣｕ含有割合は、Ｃｕ担持θアルミナ（２）の総量に対して、１．０質量％であった。 The Cu content ratio of this powder was 1.0% by mass with respect to the total amount of Cu-supported θ-alumina (2).
　　実施例２
　製造例３において得られたＰｄ担持θアルミナ（１）（Ｐｄ担持割合：０．０１質量％）０．５ｇと、製造例４において得られたＣｕ担持θアルミナ（２）（Ｃｕ担持割合：１．０質量％）０．５ｇとを、乳鉢により混合し、混合粉末として排ガス浄化用触媒を得た。 Example 2
0.5 g of Pd-supported θ-alumina (1) (Pd support ratio: 0.01% by mass) obtained in Production Example 3 and Cu-supported θ-alumina (2) obtained in Production Example 4 (Cu support ratio: 1) 0.0 mass%) and 0.5 g were mixed with a mortar to obtain an exhaust gas-purifying catalyst as a mixed powder.
　得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表３に示す。 Table 3 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
　　実施例３
　製造例３において得られたＰｄ担持θアルミナ（１）（Ｐｄ担持割合：０．０１質量％）０．５ｇと、製造例４において得られたＣｕ担持θアルミナ（２）（Ｃｕ担持割合：１．０質量％）１．０ｇとを用いた以外は、実施例２と同様にして、排ガス浄化用触媒を得た。 Example 3
0.5 g of Pd-supported θ-alumina (1) (Pd support ratio: 0.01% by mass) obtained in Production Example 3 and Cu-supported θ-alumina (2) obtained in Production Example 4 (Cu support ratio: 1) 0.0 mass%) 1.0 g was used in the same manner as in Example 2 to obtain an exhaust gas purification catalyst.
　得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表３に示す。 Table 3 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
　　比較例３
　製造例３において得られたＰｄ担持θアルミナ（１）（Ｐｄ担持割合：０．０１質量％）０．５ｇのみを用い、製造例４において得られたＣｕ担持θアルミナ（２）（Ｃｕ担持割合：１．０質量％）を用いなかった以外は、実施例２と同様にして、排ガス浄化用触媒を得た。 Comparative Example 3
Using only 0.5 g of the Pd-supported θ-alumina (1) (Pd support ratio: 0.01% by mass) obtained in Production Example 3, the Cu-supported θ-alumina (2) (Cu support ratio obtained in Production Example 4) : 1.0 mass%) was used in the same manner as in Example 2 except that an exhaust gas purifying catalyst was obtained.
　得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表３に示す。 Table 3 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　評価（ＣＯ浄化率）
　実施例２～３および比較例３の粉末０．５ｇを、０．５～１．０ｍｍのサイズのペレットに成型して試験片を調製した。 Evaluation (CO purification rate)
Test pieces were prepared by molding 0.5 g of the powders of Examples 2 to 3 and Comparative Example 3 into pellets having a size of 0.5 to 1.0 mm.
　表２に示す組成のモデルガスを用いて、このモデルガスの燃焼（空燃比Ａ／Ｆ＝１４．０）によって排出される排気ガス（温度：４００℃、流速：２．５Ｌ／ｍｉｎ）を各試験片に供給し、排ガス中のＣＯの浄化率（４００℃浄化率：％）を測定した。 Using the model gas having the composition shown in Table 2, each exhaust gas (temperature: 400 ° C., flow rate: 2.5 L / min) discharged by combustion of this model gas (air-fuel ratio A / F = 14.0) It supplied to the test piece and measured the purification rate (400 degreeC purification rate:%) of CO in waste gas.
　その結果を、表３および図２に示す。
（考察）
　図２より、比較例３に示すように単独では排ガス浄化性が十分ではない排ガス浄化用触媒であっても、実施例２および３に示す排ガス浄化用触媒のように、銅（Ｃｕ担持θアルミナ）を共存させることで、排ガス浄化性の向上を図ることができると確認された。 The results are shown in Table 3 and FIG.
(Discussion)
From FIG. 2, even if it is an exhaust gas purifying catalyst that does not have sufficient exhaust gas purifying properties by itself as shown in Comparative Example 3, as in the exhaust gas purifying catalyst shown in Examples 2 and 3, copper (Cu-supported θ-alumina) )), It was confirmed that the exhaust gas purification performance can be improved.
　　製造例５（Ｐｄ／Ａｌ２Ｏ３（２）の製造）
　θアルミナに対する硝酸パラジウム水溶液の含浸量を変更した以外は、製造例３と同様にして、Ｐｄ担持θアルミナ（２）粉末を得た。 Production Example 5 (Production of Pd / Al 2 O 3 (2))
Pd-supported θ-alumina (2) powder was obtained in the same manner as in Production Example 3, except that the amount of palladium nitrate aqueous solution impregnated into θ-alumina was changed.
　この粉末のＰｄ含有割合は、Ｐｄ担持θアルミナ（２）の総量に対して、０．５質量％であった。 The Pd content ratio of this powder was 0.5% by mass with respect to the total amount of Pd-supported θ-alumina (2).
　　実施例４
　θアルミナに、硝酸パラジウム水溶液および硝酸銅水溶液を含浸させ、乾燥後、電気炉にて、６００℃で３時間熱処理（焼成）することにより、ＰｄおよびＣｕ担持θアルミナ粉末を得た。得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表４に示す。 Example 4
θ alumina was impregnated with an aqueous palladium nitrate solution and an aqueous copper nitrate solution, dried, and then heat treated (fired) at 600 ° C. for 3 hours in an electric furnace to obtain Pd and Cu-supported θ alumina powder. Table 4 shows the Pd content, Cu content, and mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas-purifying catalyst.
　　比較例４
　製造例５において得られたＰｄ担持θアルミナ（Ｐｄ担持割合：０．５質量％）０．２５ｇと、製造例２において得られたＣｕ担持θアルミナ（Ｃｕ担持割合：３．０質量％）０．２５ｇとを、乳鉢により混合し、混合粉末として排ガス浄化用触媒を得た。 Comparative Example 4
0.25 g of Pd-supported θ-alumina obtained in Production Example 5 (Pd-supported proportion: 0.5% by mass) and Cu-supported θ-alumina obtained in Production Example 2 (Cu-supported proportion: 3.0% by mass) 0 .25 g was mixed with a mortar to obtain a catalyst for exhaust gas purification as a mixed powder.
　得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表４に示す。 Table 4 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
　　比較例５
　製造例５において得られたＰｄ担持θアルミナ（Ｐｄ担持割合：０．５質量％）０．２５ｇのみを用い、製造例２において得られたＣｕ担持θアルミナ（Ｃｕ担持割合：３．０質量％）を用いなかった以外は、比較例４と同様にして、排ガス浄化用触媒を得た。 Comparative Example 5
Using only 0.25 g of Pd-supported θ-alumina (Pd support ratio: 0.5 mass%) obtained in Production Example 5, Cu-supported θ-alumina (Cu support ratio: 3.0 mass%) obtained in Production Example 2 Exhaust gas purifying catalyst was obtained in the same manner as in Comparative Example 4 except that the above was not used.
　得られた排ガス浄化用触媒のＰｄ含有量、Ｃｕ含有量、および、Ｐｄの含有量に対するＣｕの含有量の質量比（Ｃｕ／Ｐｄ）を、表４に示す。 Table 4 shows the Pd content, the Cu content, and the mass ratio of the Cu content to the Pd content (Cu / Pd) of the obtained exhaust gas purification catalyst.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　評価（ＮＯｘおよびＣＯ浄化率）
　実施例４、比較例４および５の粉末０．５ｇを、０．５～１．０ｍｍのサイズのペレットに成型して試験片を調製した。 Evaluation (NOx and CO purification rate)
Test pieces were prepared by molding 0.5 g of the powders of Example 4 and Comparative Examples 4 and 5 into pellets having a size of 0.5 to 1.0 mm.
　表２に示す組成のモデルガスを用いて、このモデルガスの燃焼（空燃比Ａ／Ｆ＝１４．０）によって排出される排気ガス（温度：４００℃、流速：２．５Ｌ／ｍｉｎ）を各試験片に供給し、排ガス中のＮＯｘおよびＣＯの浄化率（４００℃浄化率：％）を測定した。 Using the model gas having the composition shown in Table 2, each exhaust gas (temperature: 400 ° C., flow rate: 2.5 L / min) discharged by combustion of this model gas (air-fuel ratio A / F = 14.0) It supplied to the test piece and measured the purification rate of NOx and CO in the exhaust gas (400 ° C. purification rate:%).
　その結果を、表４および図３に示す。
（考察）
　図３より、比較例５に示すように単独では排ガス浄化性が十分ではない排ガス浄化用触媒に対して、銅（Ｃｕ担持θアルミナ）を共存させる場合にも、比較例４に示すように、Ｐｄの含有割合が０．２質量％を超える場合には、排ガス浄化性の向上を図ることができないと確認された。一方、実施例４に示すように、Ｐｄの含有割合が０．２質量％以下であれば、排ガス浄化性の向上を図ることができると確認された。 The results are shown in Table 4 and FIG.
(Discussion)
From FIG. 3, as shown in Comparative Example 4, even when copper (Cu-supported θ-alumina) coexists with an exhaust gas purifying catalyst that does not have sufficient exhaust gas purifying properties alone as shown in Comparative Example 5, When the content ratio of Pd exceeds 0.2% by mass, it was confirmed that the exhaust gas purification performance cannot be improved. On the other hand, as shown in Example 4, it was confirmed that if the content ratio of Pd was 0.2% by mass or less, the exhaust gas purification performance could be improved.
　本国際出願は、２０１２年９月２８日に出願された日本国特許出願である特願２０１２－２１８５７３号、２０１３年１月３１日に出願された日本国特許出願である特願２０１３－０１７５２２号、及び２０１３年７月１７日に出願された日本国特許出願である特願２０１３－１４８７８９号に基づく優先権を主張するものであり、当該日本国特許出願である特願２０１２－２１８５７３号、特願２０１３－０１７５２２号、及び特願２０１３－１４８７８９号の全内容は、本国際出願に援用される。This international application is Japanese Patent Application No. 2012-218573 filed on September 28, 2012 and Japanese Patent Application No. 2013-017522 filed on January 31, 2013. Claiming priority based on Japanese Patent Application No. 2013-148789, which is a Japanese patent application filed on July 17, 2013, and Japanese Patent Application No. 2012-218573, which is a Japanese patent application, The entire contents of Japanese Patent Application No. 2013-017522 and Japanese Patent Application No. 2013-148789 are incorporated in this international application.
　本発明の特定の実施の形態についての上記説明は、例示を目的として提示したものである。それらは、網羅的であったり、記載した形態そのままに本発明を制限したりすることを意図したものではない。数多くの変形や変更が、上記の記載内容に照らして可能であることは当業者に自明である。The above description of specific embodiments of the present invention has been presented for purposes of illustration. They are not intended to be exhaustive or to limit the invention to the precise form described. It will be apparent to those skilled in the art that many modifications and variations are possible in light of the above description.

Claims (2)

  1. 　耐熱性酸化物に、パラジウムおよび銅、および／または、それらの合金が担持されており、
    　銅の含有量が、パラジウムの含有量よりも多く、かつ、
    　パラジウムの含有割合が、耐熱性酸化物、パラジウムおよび銅の総量に対して、０．２質量％以下であることを特徴とする、排ガス浄化用触媒。     Palladium and copper and / or alloys thereof are supported on the heat-resistant oxide,
    The copper content is greater than the palladium content, and
    A catalyst for exhaust gas purification, wherein the palladium content is 0.2% by mass or less based on the total amount of the heat-resistant oxide, palladium and copper.
  2. 　パラジウムの含有量に対する銅の含有量の質量比（Ｃｕ／Ｐｄ）が、３０以上であることを特徴とする、請求項１に記載の排ガス浄化用触媒。 2. The exhaust gas purifying catalyst according to claim 1, wherein a mass ratio (Cu / Pd) of copper content to palladium content is 30 or more.
PCT/JP2013/074999 2012-09-28 2013-09-17 Exhaust gas purifying catalyst WO2014050630A1 (en)

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JP2013017522A JP2014147877A (en) 2013-01-31 2013-01-31 Exhaust emission control catalyst
JP2013-148789 2013-07-17
JP2013148789A JP2014079749A (en) 2012-09-28 2013-07-17 Exhaust gas purifying catalyst

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07136512A (en) * 1993-09-24 1995-05-30 Mazda Motor Corp Catalyst for purifying exhaust gas from engine and production thereof
JPH07204508A (en) * 1994-01-20 1995-08-08 Natl Sci Council Palladium alloy catalyst for pyrolysis denitrification and method for producing the same
JP2006187675A (en) * 2004-12-28 2006-07-20 Mazda Motor Corp Exhaust gas purifying catalyst
JP2012159075A (en) * 2011-01-14 2012-08-23 Toyota Motor Corp Base metal exhaust emission control device of internal combustion engine

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07136512A (en) * 1993-09-24 1995-05-30 Mazda Motor Corp Catalyst for purifying exhaust gas from engine and production thereof
JPH07204508A (en) * 1994-01-20 1995-08-08 Natl Sci Council Palladium alloy catalyst for pyrolysis denitrification and method for producing the same
JP2006187675A (en) * 2004-12-28 2006-07-20 Mazda Motor Corp Exhaust gas purifying catalyst
JP2012159075A (en) * 2011-01-14 2012-08-23 Toyota Motor Corp Base metal exhaust emission control device of internal combustion engine

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