# US 7,407,911 B2 · Method of preparing a double layered, palladium-only three-way catalyst

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- Number: US 7,407,911 B2
- Document ID: US7407911B2
- Status: Granted
- Kind: B2
- Application number: 10/862,147
- Filed: 2004-06-04
- Published: 2004-11-11
- Granted: 2008-08-05
- Earliest claimed: 2003-06-04
- Assignees: Hyundai Motor Company
- Inventors: Gwon Koo Yeo
- Web page: https://patentgrep.com/patent/US7407911B2

## CPC

- B01D 53/945: {characterised by a specific catalyst}
- B01J 23/002: {Mixed oxides other than spinels, e.g. perovskite}
- B01J 23/894: {with rare earths or actinides}
- B01J 37/0244: {Coatings comprising several layers}
- B01J 23/44: Palladium
- B01J 23/63: with rare earths or actinides
- B01J 2523/00: Constitutive chemical elements of heterogeneous catalysts
- Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
- 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
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The present invention relates to a method of preparing a double layered, palladium-only three-way catalyst using three different composite oxides. More particularly, the present invention relates to a method of preparing a double layered, palladium-only three-way catalyst comprising a first coating layer (bottom layer) and a second coating layer (top layer) containing palladium by incorporating composite oxide, praseodymium oxide, and perovskite.

## Claims

### Claim 1

A method of preparing a double layered, palladium-only three-way catalyst comprising the steps of:
preparing a first catalyst slurry and a second catalyst slurry using palladium, alumina, cerium oxide and a mixing solution;
first coating of the first catalyst slurry on a ceramic monolith substrate;
drying the substrate;
calcining the substrate; and
second coating of the second catalyst slurry:
wherein said first catalyst slurry is prepared by adding 15 to 25 g/L of a mixture of cerium oxide, cerium—zirconium composite oxide [(Ce.Zr)O2] and cerium—zirconium—yttrium composite oxide [(Ce.Zr.Y)O2], proportions of which ranging from 25:60:15 to 20:60:20 by weight, with respect to the total apparent volume of the substrate to alumina; adding 2 to 5 g/L of praseodymium oxide with respect to the total apparent volume of the substrate; and adding 15 to 25 g/L of metal oxide (perovskite) selected from (LaCe)(FeCo)O3 and (LaSr)(FeCo)O3 with respect to the total apparent volume of the substrate.

### Claim 2 (depends on 1)

The method of claim 1, wherein said second catalyst slurry is prepared by reducing a palladium solution impregnated with alumina, adding 15 to 25 g/L of a mixture of cerium oxide, cerium—zirconium composite oxide [(Ce.Zr)O2] and cerium—zirconium—yttrium composite oxide [(Ce.Zr.Y)O2], proportions of which ranging from 25:60:15 to 20:60:20 by weight, with respect to the total apparent volume of the substrate, adding 2 to 5 g/L of praseodymium oxide with respect to the total apparent volume of the substrate and adding 15 to 25 g/L of metal oxide (perovskite) selected from (LaCe)(FeCo)O3 and (LaSr)(FeCo)O3 with respect to the total apparent volume of the substrate.

### Claim 3 (depends on 1)

The method of claim 1, wherein said mixing solution comprises barium oxide, lanthanum oxide, acetic acid, and water.

### Claim 4 (depends on 1)

The method of claim 1 further comprises milling said first catalyst slurry before said first coating.

### Claim 5 (depends on 1)

The method of claim 1 further comprises milling said second catalyst slurry before said second coating.

### Claim 6 (depends on 1)

The method of claim 1, wherein said drying is performed at 150° C. for two hours.

### Claim 7 (depends on 1)

The method of claim 1, wherein said calcining is performed at 150° C. for four hours.

### Claim 8

A method of reducing automobile exhaust emission components comprises using a double layered, palladium-only three-way catalyst having a substrate, a bottom layer with a ternary composite oxide disposed over said substrate, and a top layer with palladium disposed over said bottom layer.

### Claim 9 (depends on 8)

The method of claim 8, wherein said bottom layer of said double layered, palladium-only three-way catalyst comprises a first catalyst slurry that is prepared by adding 15 to 25 g/L of a mixture of cerium oxide, cerium—zirconium composite oxide [(Ce.Zr)O2] and cerium—zirconium—yttrium composite oxide [(Ce.Zr.Y)O2], proportions of which ranging from 25:60:15 to 20:60:20 by weight, with respect to the total apparent volume of the substrate to alumina; adding 2 to 5 g/L of praseodymium oxide with respect to the total apparent volume of the substrate; and adding 15 to 25 g/L of metal oxide (perovskite) selected from (LaCe)(FeCo)O3 and (LaSr)(FeCo)O3 with respect to the total apparent volume of the substrate.

### Claim 10 (depends on 9)

The method of claim 9, wherein said first catalyst slurry is milled.

### Claim 11 (depends on 10)

The method of claim 10 further comprises first catalyst slurry being coated onto said substrate, thereby forming said bottom layer.

### Claim 12 (depends on 11)

The method of claim 11 further comprises drying and calcining said substrate.

### Claim 13 (depends on 12)

The method of claim 12, wherein said top layer of said double layered, palladium-only three-way catalyst comprises a second catalyst slurry that is prepared by reducing a palladium solution impregnated with alumina, adding 15 to 25 g/L of a mixture of cerium oxide, cerium—zirconium composite oxide [(Ce.Zr)O2] and cerium—zirconium—yttrium composite oxide [(Ce.Zr.Y)O2], proportions of which ranging from 25:60:15 to 20:60:20 by weight, with respect to the total apparent volume of the substrate, adding 2 to 5 g/L of praseodymium oxide with respect to the total apparent volume of the substrate and adding 15 to 25 g/L of metal oxide (perovskite) selected from (LaCe)(FeCo)O3 and (LaSr)(FeCo)O3 with respect to the total apparent volume of the substrate.

### Claim 14 (depends on 13)

The method of claim 13, wherein said second catalyst slurry is milled.

### Claim 15 (depends on 14)

The method of claim 14 further comprises said second catalyst slurry being coated onto said substrate and above said bottom layer, thereby forming said top layer.

### Claim 16 (depends on 15)

The method of claim 15 further comprises drying and calcining said substrate.