CATALYST FOR EXHAUST GAS PURIFICATION, PRODUCTION METHOD THEREFOR, AND METHOD FOR PURIFICATION OF EXHAUST GAS USING THE CATALYST

Abstract

It is an object of the present invention to provide a catalyst for the exhaust gas purification having excellent ignition performance and NOx purification performance. The present invention provides a catalyst for the exhaust gas purification which comprises a catalytically active component (I) having palladium and barium supported on a refractory inorganic oxide (A); and a catalytically active component (II) having at least either of rhodium and platinum on a refractory inorganic oxide (B), a method for the production thereof, and a method for purifying an exhaust gas using such a catalyst.

Description

Claims

1. A catalyst for the exhaust gas purification which comprises: a catalytically active component (I) having palladium and barium supported on a refractory inorganic oxide (A); anda catalytically active component (II) having at least either of rhodium and platinum on a refractory inorganic oxide (B).

2. The catalyst for the exhaust gas purification according to claim 1, wherein the molar ratio of barium to palladium (molar ratio of barium/palladium) in the catalytically active component (I) exceeds 0 and is not more than 2.

3. The catalyst for the exhaust gas purification according to claim 2, wherein the molar ratio of barium to palladium (molar ratio of barium/palladium) in the catalytically active component (I) exceeds 0 and is below 1.

4. The catalyst for the exhaust gas purification according to claim 1, which comprises a surface layer containing the catalytically active component (I) and a lower layer containing the catalytically active component (II).

5. The catalyst for the exhaust gas purification gas according to claim 1, which comprises a surface layer containing the catalytically active component (II) and a lower layer containing the catalytically active component (I).

6. The catalyst for the exhaust gas purification according to claim 1, which comprises a layer containing the catalytically active component (I) and the catalytically active component (II).

7. The catalyst for the exhaust gas purification according to claim 1, wherein the amount of the catalytically active component (I) used is in the range of 10 to 300 g, per liter of the catalyst for the exhaust gas purification.

8. The catalyst for the exhaust gas purification according to claim 1, wherein the amount of the catalytically active component (II) used is in the range of 10 to 300 g, per liter of the catalyst for the exhaust gas purification.

9. The catalyst for the exhaust gas purification according to claim 1, wherein the weight ratio of the catalytically active component (I) and the catalytically active component (II) (weight ratio of catalytically active component (I): catalytically active component (II)) is in the range of 1:30 to 30:1.

10. A method for the production of a catalyst for the exhaust gas purification which comprises: a step of supporting palladium and barium on a refractory inorganic oxide (A) to yield a catalytically active component (I);a step of supporting at least either of rhodium and platinum on a refractory inorganic oxide (B) to yield a catalytically active component (II);a step of supporting the catalytically active component (I) on a refractory three-dimensional structure to yield a precursor catalyst (I); anda step of supporting the catalytically active component (II) on said precursor catalyst (I).

11. A method for the production of a catalyst for the exhaust gas purification which comprises: a step of supporting palladium and barium on a refractory inorganic oxide (A) to yield a catalytically active component (I);a step of supporting at least either of rhodium and platinum on a refractory inorganic oxide (B) to yield a catalytically active component (II);a step of supporting the catalytically active component (II) on a refractory three-dimensional structure to yield a precursor catalyst (II); anda step of supporting the catalytically active component (I) on said precursor catalyst (II).

12. A method for the production of a catalyst for the exhaust gas purification which comprises: a step of supporting palladium and barium on a refractory inorganic oxide (A) to yield a catalytically active component (I);a step of supporting at least either of rhodium and platinum on a refractory inorganic oxide (B) to yield a catalytically active component (II); anda step of supporting the catalytically active component (I) and the catalytically active component (II) on a refractory three-dimensional structure.

13. The method for the production of a catalyst for the exhaust gas purification according to claim 10, wherein water-soluble barium is used as a barium source in the step of yielding the catalytically active component (I).

14. The method for the production of a catalyst for the exhaust gas purification according to claim 11, wherein water-soluble barium is used as a barium source in the step of yielding the catalytically active component (I).

15. The method for the production of a catalyst for the exhaust gas purification according to claim 12, wherein water-soluble barium is used as a barium source in the step of yielding the catalytically active component (I).

16. A method for purifying an exhaust gas which comprises a step of contacting the exhaust gas with the catalyst for the exhaust gas purification set forth in claim 1.