EXHAUST GAS PURIFICATION CATALYST AND EXHAUST GAS PURIFICATION METHOD USING THE SAME

• US 20200129962A1
• Filed: 04/26/2018
• Published: 04/30/2020
• Est. Priority Date: 04/28/2017
• Status: Active Grant

• Current Assignee: Umicore Shokubai Japan Co., Ltd. (Umicore S.A.)
• Original Assignee: Umicore Shokubai Japan Co., Ltd. (Umicore S.A.)
• Inventors: KUNO, Hirotaka, IKEGAMI, Takahiro, MIKITA, Kosuke, NAKASHIMA, Masashi, MINAMI, Shigekazu, IKEDA, Masanori
• Granted Patent: US 11,141,713 B2
• Time in Patent Office: Days
• CPC Class Codes: B01D 2255/1023 Palladium
• CPC Class Codes: B01D 2255/1025 Rhodium
• CPC Class Codes: B01D 2255/2065 Cerium
• CPC Class Codes: B01D 2255/9022 Two layers
• CPC Class Codes: B01D 2257/404 Nitrogen oxides other than dinitrogen oxide
• CPC Class Codes: B01D 2257/502 Carbon monoxide
• CPC Class Codes: B01D 2257/702 Hydrocarbons
• CPC Class Codes: B01D 2258/01 Engine exhaust gases
• CPC Class Codes: B01D 53/865 characterised by a specific catalyst
• CPC Class Codes: B01D 53/94 by catalytic processes
• CPC Class Codes: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 35/19 Catalysts containing parts with different compositions
• CPC Class Codes: B01J 35/56 Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: B01J 37/0215 Coating
• CPC Class Codes: B01J 37/0244 Coatings comprising several layers
• CPC Class Codes: B01J 37/038 to form slurries or suspensions, e.g. a washcoat
• CPC Class Codes: F01N 3/10 by thermal or catalytic conversion of noxious components of exhaust by using other chemical processes, chemical aspects of catalytic conversion, e.g. using specified catalysts, B01D53/34
• CPC Class Codes: F01N 3/28 Construction of catalytic reactors

Abstract

In order to provide an exhaust gas purification catalyst capable of purifying hydrocarbons, carbon monoxide, and nitrogen oxides in exhaust gas at low temperatures, the exhaust gas purification catalyst according to the present invention includes: a region (2) containing palladium on a three-dimensional structure (1), and a first region (3) and a second region (4) provided on the region (2) in order from an inflow side of exhaust gas to an outflow side of exhaust gas. The concentration of rhodium contained in the first region (3) is higher than the concentration of rhodium contained in the second region (4).

Claims

1. An exhaust gas purification catalyst comprising:

a region containing palladium, the region being provided on a three-dimensional structure; and

a first region and a second region being provided on the region containing palladium in order from an inflow side of exhaust gas to an outflow side of exhaust gas;

wherein the concentration of rhodium contained in the first region is higher than the concentration of rhodium contained in the second region.

2. The exhaust gas purification catalyst according to claim 1, wherein the concentration of rhodium contained in the first region is from 2 to 5 times the concentration of rhodium contained in the second region.

3. The exhaust gas purification catalyst according to claim 1, wherein the concentration of rhodium contained in the first region is from 1.0 mass % to 10 mass %, and the concentration of rhodium contained in the second region is not less than 0 mass % and less than 1.0 mass %.

4. The exhaust gas purification catalyst according to claim 1, wherein an amount of rhodium contained in the first region is from 0.35 g/L to 1.2 g/L in terms of metal relative to 1 liter of the three-dimensional structure, and an amount of rhodium contained in the second region is from 0.01 g/L to 0.3 g/L in terms of metal relative to 1 liter of the three-dimensional structure.

5. The exhaust gas purification catalyst according to claim 1, wherein the concentration of cerium contained in the region containing palladium is higher than the concentration of cerium contained in either the first region and/or the concentration of cerium contained in the second region.

6. The exhaust gas purification catalyst according to claim 1, wherein the concentration of cerium contained in the second region is higher than the concentration of cerium contained in the first region.

7. The exhaust gas purification catalyst according to claim 1, wherein the concentration of cerium contained in the region containing palladium is from 13 mass % to 40 mass % in terms of CeO₂, and the concentration of cerium contained in either the first region and/or the concentration of cerium contained in the second region is not less than 0 mass % and less than 13 mass % in terms of CeO₂.

8. The exhaust gas purification catalyst according to claim 1, wherein the concentration of cerium contained in the first region is from 0 mass % to 4 mass % in terms of CeO₂, and the concentration of cerium contained in the second region is not less than 5 mass % and less than 13 mass % in terms of CeO₂.

9. The exhaust gas purification catalyst according to claim 1, wherein an amount of cerium contained in the region containing palladium is from 10 g/L to 50 g/L in terms of CeO₂ relative to 1 liter of the three-dimensional structure, and an amount of cerium contained in either the first region and/or an amount of cerium contained in the second region is not less than 0 g/L and less than 10 g/L in terms of CeO₂ relative to 1 liter of the three-dimensional structure.

10. The exhaust gas purification catalyst according to claim 1, wherein when the cerium in the region containing palladium is a cerium complex oxide (3), the cerium in the first region is a cerium complex oxide (1) and the cerium in the second region is a cerium complex oxide (2), the cerium complex oxide (3) has a higher concentration of cerium in terms of CeO₂ than either the cerium complex oxide (1) and/or the cerium complex oxide (2).

11. The exhaust gas purification catalyst according to claim 1, wherein the cerium complex oxide (2) in the second region has the same or higher concentration of cerium in terms of CeO₂ in comparison to the cerium complex oxide (1) in the first region.

12. The exhaust gas purification catalyst according to claim 1, wherein the amount of cerium contained in the cerium complex oxide (3) in the region containing palladium is from 30 mass % to 70 mass % in terms of CeO₂, and the amount of cerium contained in the cerium complex oxide (2) in the second region is not less than 5 mass % and less than 30 mass % in terms of CeO₂.

13. The exhaust gas purification catalyst according to claim 1, wherein the amount of palladium contained in the region containing palladium is from 0.1 g/L to 20 g/L in terms of metal relative to 1 liter of the three-dimensional structure, and the concentration of palladium contained in the region containing palladium is from 1 mass % to 10 mass %.

14. The exhaust gas purification catalyst according to claim 1, wherein the amount of all components provided in each region is greater in the region containing palladium than the second region and is greater in the second region than the first region;

and relative to 1 liter of the three-dimensional structure,

the amount of all components provided in the region containing palladium is from 50 g/L to 150 g/L,

the amount of all components provided in the first region is not less than 10 g/L and less than 60 g/L, and

the amount of all components provided in the second region is from 50 g/L to 90 g/L.

15. The exhaust gas purification catalyst according to claim 1, wherein the three-dimensional structure is from 30 mm to 200 mm, the region containing palladium is from 60% to 100% relative to the length of the three-dimensional structure, the first region is from 20 mm to 50 mm, and the second region is provided on the region containing palladium, at a portion where the first region is not provided at the outflow side of exhaust gas.

16. A method for purifying exhaust gas, comprising purifying exhaust gas using the exhaust gas purification catalyst according to claim 1.

17. The method for purifying exhaust gas according to claim 16, wherein exhaust gas having a temperature from 100°

C. to 500°

C. is purified.

18. The method for purifying exhaust gas according to claim 16, wherein exhaust gas having a space velocity of not less than 80000 h⁻

1 is purified.