Exhaust gas purifying catalyst

Patent metadata

Field	Value
Publication number	US-2016288052-A1
Application number	US-201415037070-A
Country	US
Kind code	A1
Filing date	Dec 4, 2014
Priority date	Dec 9, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

The exhaust gas-purifying catalyst of the invention includes a noble metal, and crystallites that form CZ composite metal particles which serve as a carrier supporting the noble metal and contain at least zirconium (Zr) and cerium (Ce). The CZ composite oxide particles (crystallites) further contain crystal growth-suppressing fine particles which are fine metal particles comprising primarily a metallic element M that melts at 1,500° C. or above and which suppress crystal growth by the CZ composite oxide particles. The content of the metallic element M included in the CZ composite oxide particles, expressed in terms of the oxide thereof, is 0.5 mol % or less of the total oxide.

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:
a noble metal and crystallites that form CZ composite oxide particles which serve as a carrier supporting the noble metal and contain at least zirconium (Zr) and cerium (Ce), wherein the CZ composite oxide particles (crystallites) further contain crystal growth-suppressing fine particles which comprise primarily a metallic element M that melts at 1,500° C. or above and suppress crystal growth of the CZ composite oxide particles, and the content of the metallic element M included in the CZ composite oxide particles, expressed in terms of the oxide thereof, is 0.5 mol % or less of the total oxide.

2 . The exhaust gas-purifying catalyst according to claim 1 , wherein the metallic element M is of at least one type selected from the group consisting of elements belonging to Groups 5 to 10 and Periods 5 and 6 of the periodic table.

3 . The exhaust gas-purifying catalyst according to claim 1 , wherein the metallic element M is a metallic element for which the melting point of uncombined metal composed of element M is at least 2,000° C.

4 . The exhaust gas-purifying catalyst according to claim 1 , wherein the metallic element M is of at least one type selected from the group consisting of Nb, Mo, Ta and W.

5 . The exhaust gas-purifying catalyst according to claim 1 , wherein the content of the metallic element M included in the CZ composite oxide particles, expressed in terms of the oxide thereof, is from 0.005 mol % to 0.1 mol % of the total oxide.

6 . The exhaust gas-purifying catalyst according to claim 1 , wherein the correlation coefficient σ (Ce, M) calculated from formula (1) below is 0.6 or more:

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Formula
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Ce

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Ce

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M

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Assignees

• Cataler Corp

Inventors

• Matsueda Satoshi
• Hirai Akimasa
• Taki Kenichi

Classifications

• B01D2255/20715

  Zirconium · CPC title

• B01D2255/2092

  Aluminium · CPC title

• B01D2255/1021

  Platinum · CPC title

• B01J23/6527

  Tungsten · CPC title

• B01J23/10

  of rare earths · CPC title