CATALYTIC MATERIAL, PRODUCTION METHOD THEREFOR, AND DIESEL PARTICULATE FILTER

Abstract

Disclosed is a catalytic material for removing diesel particulates, which comprises a composite oxide which contains zirconium as a primary component and a rare-earth metal except for cerium and yttrium. The composite oxide has a crystallite diameter of 13 nm to 40 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram showing a diesel particulate filter with an oxidation catalyst, according to one embodiment of the present invention, wherein the diesel particulate filter is installed in an exhaust passage of a diesel engine.

FIG. 2 is a front view schematically showing the diesel particulate filter.

FIG. 3 is a vertical sectional view schematically showing the diesel particulate filter.

FIG. 4 is an enlarged sectional view showing a porous wall of the diesel particulate filter.

FIG. 5 is an explanatory diagram of a mechanism for burning of particulates.

FIG. 6 is a graph showing data on a relationship of a calcinating temperature of a coprecipitated precursor, a T50 light-off temperature, and a C300 high-temperature conversion efficiency, which has been obtained from one Example.

FIG. 7 is a graph showing a relationship between a calcinating temperature of a coprecipitated precursor and a carbon burnup rate.

FIG. 8 is a graph showing respective carbon burnup rates in particulate oxidation catalysts made of various types of Pt-loaded powders, which is disclosed in PPA (Japanese Patent Application Serial No. 2005-241744)

Claims

1. A catalytic material for removing diesel particulates, comprising a composite oxide which contains zirconium as a primary component and a rare-earth metal except for cerium and yttrium, said composite oxide having a crystallite diameter of 13 nm to 40 nm.

2. The catalytic material according to claim 1, wherein a content rate of said rare-earth metal contained in said composite oxide is set in the range of 3 mol % to 12 mol %.

3. The catalytic material as defined in claim 1, wherein said rare-earth metal is at least one selected from the group consisting of scandium, neodymium and ytterbium.

4. The catalytic material according to claim 2, wherein said rare-earth metal is at least one selected from the group consisting of scandium, neodymium and ytterbium.

5. A method for production of the catalytic material according to claim 1, comprising the steps of: obtaining a coprecipitated precursor which contains zirconium as a primary component and a rare-earth metal except for cerium and yttrium; andcalcinating said coprecipitated precursor in an atmosphere at a temperature ranging from 700° C. to 1200° C.

6. A diesel particulate filter adapted to be disposed in an exhaust passage of a diesel engine, comprising a catalytic layer formed to define a contact surface with exhaust gas passing through said exhaust passage, said catalytic layer being made of a catalytic material including a composite oxide which contains zirconium as a primary component and a rare-earth metal except for cerium and yttrium, said composite oxide having a crystallite diameter of 13 nm to 40 nm.

7. The diesel particulate filter according to claim 6, wherein a content rate of said rare-earth metal contained in said composite oxide is set in the range of 3 mol % to 12 mol %.

8. The diesel particulate filter according to claim 6, wherein said rare-earth metal is at least one selected from the group consisting of scandium, neodymium and ytterbium.

9. The diesel particulate filter according to claim 7, wherein said rare-earth metal is at least one selected from the group consisting of scandium, neodymium and ytterbium.