# US 8,465,711 B2 · Exhaust gas purification catalyst and method for purifying exhaust gas by using same

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- Number: US 8,465,711 B2
- Document ID: US8465711B2
- Status: Granted
- Kind: B2
- Application number: 12/737,868
- Filed: 2009-08-27
- Published: 2011-07-07
- Granted: 2013-06-18
- Earliest claimed: 2008-08-27
- Assignees: Umicore Shokubai Japan Co., Ltd.; Umicore Shokubai USA Inc.
- Applicants: Masanori Ikeda; Kosuke Mikita; Takahiro Ikegami; Yuji Ogino; Hideki Goto
- Inventors: Masanori Ikeda; Kosuke Mikita; Takahiro Ikegami; Yuji Ogino; Hideki Goto
- Web page: https://patentgrep.com/patent/US8465711B2

## CPC

- B01D 53/945: {characterised by a specific catalyst}
- B01J 21/04: Alumina
- B01J 23/63: with rare earths or actinides
- B01J 37/0036: {Grinding}
- B01J 37/0201: {Impregnation}
- B01J 37/0207: {Pretreatment of the support}
- B01J 37/0248: {Coatings comprising impregnated particles}
- B01J 37/03: Precipitation; Co-precipitation
- B01J 37/033: {Using Hydrolysis}
- B01J 37/038: {to form slurries or suspensions, e.g. a washcoat}
- B01J 37/04: Mixing {(B01J37/0009, B01J37/0018 take precedence)}
- B01D 2255/1021: Platinum
- B01D 2255/1023: Palladium
- B01D 2255/1025: Rhodium
- B01D 2255/206: Rare earth metals
- B01D 2255/2092: Aluminium
- B01D 2255/407: Zr-Ce mixed oxides
- B01D 2255/908: O2-storage component incorporated in the catalyst
- B01D 2258/014: Stoichiometric gasoline engines
- F01N 2370/02: used in catalytic reactors
- Y02T 10/12: Improving ICE efficiencies
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An exhaust gas purification catalyst of the present invention contains at least a precious metal coated with lanthanum-containing alumina. In at least one embodiment, it is possible to provide: an exhaust gas purification catalyst which can (i) have an increase in heat resistance, and (ii) inhibit the precious metal from being mixed in alumina and therefore inhibit the precious metal from forming a solid solution in combination with alumina; and a method for efficiently purifying, by use of the catalyst, an exhaust gas emitted from an internal-combustion engine.

## Claims

### Claim 1

An exhaust gas purification catalyst comprising:
a complex comprising a precious metal and a cerium oxide, wherein the complex is coated with a lanthanum-containing alumina, and
pores having a diameter of 160 nm to less than 1000 nm, which account for 5% to 20% of total pore volume of the catalyst.

### Claim 2 (depends on 1)

The catalyst as set forth in claim 1,
further comprising pores having a diameter of less than 160 nm, which account for 70% to 90% of total pore volume of the catalyst.

### Claim 3 (depends on 1)

The catalyst as set forth in claim 1, wherein:
the catalyst is capable of maintaining the precious metal after the catalyst is exposed to an oxygen-excess gas having a temperature of 950° C. to 1000° C.

### Claim 4 (depends on 3)

The catalyst as set forth in claim 3, wherein:
an exposed surface area of the precious metal is reduced or unchanged when the catalyst is exposed to said gas.

### Claim 5 (depends on 3)

The catalyst as set forth in claim 3, wherein:
20% or less of the precious metal in atomic ratio is mixed into alumina to form a solid solution of alumina and the precious metal after the catalyst is exposed to said gas.

### Claim 6 (depends on 1)

The catalyst as set forth in claim 1, further comprising:
platinum, palladium or a combination thereof.

### Claim 7 (depends on 1)

The catalyst as set forth in claim 1, wherein:
a compound comprising the precious metal and the cerium oxide is formed at an interface between the precious metal and the cerium oxide in the complex.

### Claim 8 (depends on 7)

The catalyst as set forth in claim 7, wherein:
an amount of the cerium oxide contained in the complex is greater than an amount of the compound contained in the complex.

### Claim 9 (depends on 1)

The catalyst as set forth in claim 1, wherein:
an amount of the cerium oxide contained in the complex is 1% by mass to 30% by mass with respect to a total amount of the precious metal, the cerium oxide, lanthanum, and alumina in the catalyst.

### Claim 10 (depends on 1)

The catalyst as set forth in claim 1, wherein:
the catalyst is capable of maintaining the complex after the catalyst is exposed to an exhaust gas having a temperature of 950° C. to 1000° C., and wherein the exhaust gas is emitted from an internal-combustion engine.

### Claim 11 (depends on 10)

The catalyst as set forth in claim 10, wherein:
when the catalyst is exposed to said gas, an exposed surface area of the precious metal is reduced by a percentage of 0% to 87% with respect to an exposed surface area of the precious metal before the exposure of the catalyst to said gas.

### Claim 12 (depends on 11)

The catalyst as set forth in claim 11, wherein:
the catalyst is capable of absorbing 30% to 100% oxygen from said exhaust gas.

### Claim 13 (depends on 1)

The catalyst as set forth in claim 1, further comprising:
platinum, palladium, or a combination thereof, wherein the platinum, palladium or the combination thereof is not coated with lanthanum-containing alumina.

### Claim 14 (depends on 1)

The catalyst as set forth in claim 1, wherein:
the catalyst is supported on a three-dimensional structure.

### Claim 15 (depends on 1)

The catalyst as set forth in claim 1, further comprising:
a fire-resistant inorganic oxide.

### Claim 16 (depends on 15)

The catalyst as set forth in claim 15, wherein:
the fire-resistant inorganic oxide has a melting point of not less than 1000° C.

### Claim 17 (depends on 1)

The catalyst as set forth in claim 1, further comprising:
a cerium oxide, a ceria-zirconia composite oxide or a combination thereof, wherein the cerium oxide, the ceria-zirconia composite oxide or the combination thereof is not coated with lanthanum-containing alumina.

### Claim 18 (depends on 1)

The catalyst as set forth in claim 1, wherein:
the precious metal is rhodium.

### Claim 19 (depends on 1)

A method for purifying an exhaust gas, the method comprising the step of:
exposing an exhaust gas purification catalyst as set forth in claim 1 to an exhaust gas emitted from an internal-combustion engine.

### Claim 20 (depends on 1, 2)

A method for purifying an exhaust gas, the method comprising the steps of:
(i) exposing an exhaust gas purification catalyst as set forth in claim 1 or 2 to a first exhaust gas having (I) a temperature in a range of 800° C. to 1000° C. and (II) an air-fuel ratio in a range of 10 to 18.6; and
(ii) exposing, after the step (i), the exhaust gas purification catalyst to a second exhaust gas which (1) has a temperature in a range of 0° C. to 750° C., and (2) is emitted from an internal-combustion engine.

### Claim 21 (depends on 1)

A method for producing an exhaust gas purification catalyst as set forth in claim 1, the method comprising the step of:
producing a gel in which a complex comprising a precious metal and a cerium oxide is coated with a lanthanum-containing alumina gel.

### Claim 22 (depends on 21)

The method as set forth in claim 21, the method further comprising the steps of:
turning, into a slurry, the gel in which the complex comprising the precious metal and the cerium oxide is coated with the lanthanum-containing alumina gel;
coating a three-dimensional structure with the slurry by washcoating; and
drying and baking the three-dimensional structure which is coated with the slurry.