Exhaust gas purifying catalyst

Patent metadata

Field	Value
Publication number	US-2016279607-A1
Application number	US-201415037345-A
Country	US
Kind code	A1
Filing date	Dec 4, 2014
Priority date	Dec 9, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

The exhaust gas-purifying catalyst of the invention contains oxide particles having interdispersed therein A crystallites that are loaded with a noble metal and B crystallites that are not loaded with a noble metal. The A crystallites loaded with a noble metal are composed of an oxide containing at least one of zirconium (Zr) and cerium (Ce). The B crystallites not loaded with a noble metal are composed of a cerium (Ce)-containing oxide which has a higher Ce content (mol %) than the oxide making up the A crystallites. The oxide particles have a specific surface area after 5 hours of heat treatment at 1,150° C. in open air of 30 m 2 /g or more.

First claim

1 . An exhaust gas-purifying catalyst that is disposed in an exhaust pipe for an internal combustion engine and purifies exhaust gases discharged from the internal combustion engine, comprising:
oxide particles having interdispersed therein A crystallites that are loaded with a noble metal and B crystallites that are not loaded with a noble metal, wherein the A crystallites loaded with a noble metal are composed of an oxide containing at least one of zirconium (Zr) and cerium (Ce), the B crystallites not loaded with a noble metal are composed of a cerium (Ce)-containing oxide having a higher Ce content (mol %) than the oxide making up the A crystallites, the oxide particles have a specific surface area after 5 hours of heat treatment at 1,150° C. in open air of 30 m2/g or more, and the A crystallites and the B crystallites are each present within the oxide particles in a highly interdispersed manner such that, as observed by electron microscopy, ten or more crystallites of the same type are nowhere mutually contiguous.

2 . The exhaust gas-purifying catalyst according to claim 1 , wherein
the content of cerium (Ce) included in the oxide making up the A crystallites, which is expressed in terms of cerium oxide, is from 0 to 30 mol % of the total oxide, and the content of cerium (Ce) included in the oxide making up the B crystallites, which is expressed in terms of cerium oxide, is from 35 to 99 mol % of the total oxide.

3 . The exhaust gas-purifying catalyst according to claim 1 , wherein the A crystallites are composed of an oxide containing zirconium (Zr) and also yttrium (Y).

4 . The exhaust gas-purifying catalyst according to claim 1 , wherein the B crystallites are composed of an oxide containing cerium (Ce) and also zirconium (Zr).

5 . The exhaust gas-purifying catalyst according to claim 1 , wherein the A crystallites and the B crystallites are each present within the oxide particles in a highly interdispersed manner such that, as observed by electron microscopy, seven or more crystallites of the same type are nowhere mutually contiguous.

Assignees

• Cataler Corp

Inventors

• Matsueda Satoshi
• Hirai Akimasa
• Taki Kenichi

Classifications

• B01D2255/9207

  Specific surface · CPC title

• B01D2255/2065

  Cerium · CPC title

• B01D2255/2063

  Lanthanum · CPC title

• B01D2255/9202

  Linear dimensions · CPC title

• B01J23/44

  Palladium · CPC title