# US 10,765,998 B2 · Three-way catalyst for purifying gasoline engine exhaust gas

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- Number: US 10,765,998 B2
- Document ID: US10765998B2
- Status: Granted
- Kind: B2
- Application number: 16/302,749
- Filed: 2017-04-11
- Published: 2019-10-17
- Granted: 2020-09-08
- Earliest claimed: 2016-05-25
- Assignees: N.E. Chemcat Corporation
- Applicants: N.E. Chemcat Corporation
- Inventors: Takuya Katoh; Akito Takayama
- Web page: https://patentgrep.com/patent/US10765998B2

## CPC

- B01D 53/945: {characterised by a specific catalyst}
- B01D 53/94: by catalytic processes
- B01J 23/63: with rare earths or actinides
- B01J 35/19: {Catalysts containing parts with different compositions}
- B01J 35/396: {Distribution of the active metal ingredient}
- B01J 35/57: Honeycombs
- B01J 37/0225: {of metal substrates}
- B01J 37/0236: {Drying, e.g. preparing a suspension, adding a soluble salt and drying}
- B01J 37/0244: {Coatings comprising several layers}
- B01J 37/0248: {Coatings comprising impregnated particles}
- B01J 37/08: Heat treatment {(B01J37/0009, B01J37/0018 take precedence)}
- F01N 3/10: by thermal or catalytic conversion of noxious components of exhaust
- F01N 3/101: {Three-way catalysts}
- F01N 3/28: Construction of catalytic reactors
- F01N 3/281: {Metallic honeycomb monoliths made of stacked or rolled sheets, foils or plates}
- B01D 2255/1023: Palladium
- B01D 2255/1025: Rhodium
- B01D 2255/2042: Barium
- B01D 2255/2063: Lanthanum
- B01D 2255/2065: Cerium
- B01D 2255/20715: Zirconium
- B01D 2255/407: Zr-Ce mixed oxides
- B01D 2255/9022: Two layers
- B01D 2255/9155: Wall flow filters
- 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

A three-way catalyst for purifying exhaust including noble metal components, enables sintering of the noble metal to be suppressed even at high temperature, enables carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) to be removed and a method for purifying exhaust gas. A carrier having a honeycomb structure is coated with two or more layers of the catalyst compositions, an upper layer including a heat resistant inorganic oxide supporting Pd and a La-containing oxide, a lower layer including a heat resistant inorganic oxide supporting Rh. The content of La in terms of La2O3 is 9.6 g/L to 23 g/L, the content of Ce in terms of CeO2 is 5 g/L to 20 g/L, and the content of Ba in terms of BaO is 1.2 g/L or less per unit volume of the honeycomb structure.

## Claims

### Claim 1

A three-way catalyst for purifying gasoline engine exhaust gas, the three-way catalyst comprising:
a carrier having a honeycomb structure, and
a first catalyst layer and a second catalyst layer on the carrier to remove carbon monoxide, hydrocarbons, and nitrogen oxides in gasoline engine exhaust gas,
wherein:
the first catalyst layer is composed of a first catalyst composition comprising a heat resistant inorganic oxide supporting Pd and a La-containing oxide,
the second catalyst layer is composed of a second catalyst composition comprising a heat resistant inorganic oxide supporting Rh,
the first catalyst layer is disposed farther from the carrier than the second catalyst layer,
the heat resistant inorganic oxide in at least one of the first catalyst composition and the second catalyst composition comprises a Ce-containing oxide, and
in the three-way catalyst, a content of La in terms of La2O3 is 9.6 g/L to 23 g/L, and a content of Ce in terms of CeO2 is 5 g/L to 20 g/L.

### Claim 2 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein the first catalyst composition alone comprises the La-containing oxide and the content of La in terms of La2O3 is 9.6 g/L to 20 g/L.

### Claim 3 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein the heat resistant inorganic oxide in the first catalyst composition is one or more heat resistant inorganic oxides selected from the group consisting of γ-alumina, γ-alumina to which La is added, ceria, cerium-zirconium composite oxide, and cerium-zirconium composite oxide to which La is added.

### Claim 4 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein a content of Pd is 0.1 g/L to 12 g/L per unit volume of the honeycomb structure.

### Claim 5 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein at least one of the first catalyst composition and the second catalyst composition further comprises a Ba component, and a content of Ba in terms of BaO is no more than 0.1 g/L per unit volume of the honeycomb structure.

### Claim 6 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein the heat resistant inorganic oxide in the first catalyst composition comprises cerium-zirconium composite oxide in a content of 1 g/L to 50 g/L per unit volume of the honeycomb structure.

### Claim 7 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein a content of Rh is 0.01 g/L to 3 g/L per unit volume of the honeycomb structure.

### Claim 8 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein the heat resistant inorganic oxide in the second catalyst composition comprises cerium-zirconium composite oxide in a content of 5 g/L to 100 g/L per unit volume of the honeycomb structure.

### Claim 9 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein at least one of the first catalyst composition and the second catalyst composition does not comprise Ba and wherein the first catalyst composition does not comprise Rh.

### Claim 10 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein the first catalyst composition and the second catalyst composition do not comprise Ba.

### Claim 11 (depends on 1)

The three-way catalyst for purifying gasoline engine exhaust gas according to claim 1, wherein at least one of the first catalyst composition and the second catalyst composition further comprises a Ba component, and a content of Ba in terms of BaO is no more than 1.2 g/L per unit volume of the honeycomb structure.