# US 8,569,201 B2 · Exhaust gas purifying catalyst and method for manufacturing the same

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- Number: US 8,569,201 B2
- Document ID: US8569201B2
- Status: Granted
- Kind: B2
- Application number: 13/592,998
- Filed: 2012-08-23
- Published: 2012-12-20
- Granted: 2013-10-29
- Earliest claimed: 2008-09-02
- Assignees: Nissan Motor Co., Ltd.
- Applicants: Tetsuro Naito; Masanori Nakamura; Hironori Wakamatsu
- Inventors: Tetsuro Naito; Masanori Nakamura; Hironori Wakamatsu
- Web page: https://patentgrep.com/patent/US8569201B2

## CPC

- B01J 23/63: with rare earths or actinides
- B01D 53/945: {characterised by a specific catalyst}
- B01J 23/58: with alkali- or alkaline earth metals
- B01J 35/394: {Metal dispersion value, e.g. percentage or fraction}
- B01J 37/0244: {Coatings comprising several layers}
- B01J 37/0248: {Coatings comprising impregnated particles}
- F01N 3/0842: {Nitrogen oxides}
- B01D 2255/1025: Rhodium
- B01D 2255/206: Rare earth metals
- B01D 2255/20715: Zirconium
- B01D 2255/91: NOx-storage component incorporated in the catalyst
- F01N 2370/02: used in catalytic reactors
- Y02T 10/12: Improving ICE efficiencies
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- 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)
- 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 purifying catalyst includes: rhodium; a zirconium-containing oxide which supports rhodium, and comprises: at least one element selected from the group consisting of calcium, lanthanum, cerium, neodymium and yttrium; and zirconium; and a NOx absorbing material comprising at least one selected from the group consisting of magnesium, barium, sodium, potassium and cesium. A degree of dispersion of rhodium is 20% or more after baking at 900° C. in air for three hours. A method for manufacturing the exhaust gas purifying catalyst includes: mixing the zirconium-containing oxide with water, thereby preparing an aqueous liquid of the zirconium-containing oxide; and supporting rhodium on the zirconium-containing oxide by mixing the aqueous liquid of the zirconium-containing oxide with an aqueous solution of a rhodium salt. A pH of a mixed liquid of the aqueous solution of the rhodium salt and the aqueous liquid of the zirconium-containing oxide is adjusted to 7 or more.

## Claims

### Claim 1

A method for manufacturing an exhaust gas purifying catalyst, comprising:
mixing a zirconium-containing oxide that comprises:
at least one element selected from the group consisting of calcium, lanthanum, cerium, neodymium and yttrium; and zirconium with water, thus preparing an aqueous liquid of the zirconium-containing oxide; and
supporting rhodium on the zirconium-containing oxide by mixing the aqueous liquid of the zirconium-containing oxide with an aqueous solution of a rhodium salt,
wherein a pH of a mixed liquid of the aqueous solution of the rhodium salt and the aqueous liquid of the zirconium-containing oxide is adjusted to 7 or more.

### Claim 2 (depends on 1)

The method for manufacturing an exhaust gas purifying catalyst according to claim 1, wherein a pH of the aqueous solution of the rhodium salt and a pH of the aqueous liquid of the zirconium-containing oxide are both adjusted to 7 or more.

### Claim 3 (depends on 1)

The method for manufacturing an exhaust gas purifying catalyst according to claim 1, wherein the rhodium salt is hexammine rhodium salt.

### Claim 4 (depends on 1)

The method for manufacturing an exhaust gas purifying catalyst according to claim 1, wherein a content ratio of zirconium to the element (Zr:element) is 99.5:0.5 to 95:5 in a molar basis.