IPC분류정보
| 국가/구분 |
United States(US) Patent
등록
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| 국제특허분류(IPC7판) |
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| 출원번호 |
US-0710922
(2004-08-12)
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발명자
/ 주소 |
- Li,John
- Watkins,William
- Goralski, Jr.,Christian
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| 출원인 / 주소 |
- Ford Global Technologies, LLC
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| 대리인 / 주소 |
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| 인용정보 |
피인용 횟수 :
0 인용 특허 :
31 |
초록
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The present invention provides a method of removing harmful gases from an automobile exhaust. The method of the invention comprises contacting a thermally stable NOx trap composition with a first exhaust gas mixture at a temperature of at least 200째 C. The first exhaust gas mixture includes exhaust
The present invention provides a method of removing harmful gases from an automobile exhaust. The method of the invention comprises contacting a thermally stable NOx trap composition with a first exhaust gas mixture at a temperature of at least 200째 C. The first exhaust gas mixture includes exhaust gases from an internal combustion engine operating in a fuel-lean condition. After, NOx has been absorbed onto the NOx absorber material, the NOx trap composition is then contacted with a second exhaust gas composition. In this step, the second exhaust gas mixture includes exhaust gases from an internal combustion engine operating in a fuel-rich condition. The present invention also provides the NOx trap composition used in the method. The NOx trap of the invention includes a precious metal, a NOx absorber material, an oxide that inhibits the decrease in NOx storing ability of the NOx trap composition, and a support material.
대표청구항
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The invention claimed is: 1. A method of removing harmful gases from an automobile exhaust containing NOx, CO, and hydrocarbons the method comprising: contacting a NOx trap composition with a first exhaust gas mixture at a temperature of at least 200 째C., the first exhaust gas mixture comprising ex
The invention claimed is: 1. A method of removing harmful gases from an automobile exhaust containing NOx, CO, and hydrocarbons the method comprising: contacting a NOx trap composition with a first exhaust gas mixture at a temperature of at least 200 째C., the first exhaust gas mixture comprising exhaust gases from an internal combustion engine operating in a fuel-lean condition and the NOx trap composition comprising: a precious metal; a NOx absorber material; an oxide that inhibits the decrease in NOx storing ability of the NOx trap composition, wherein proximity between oxidizing components and trapping components is optimized to maximize spillover; and a support material; and contacting the NOx trap composition with a second exhaust gas composition at a temperature of at least 200째 C., the second exhaust gas mixture comprising exhaust gases from an internal combustion engine operating in a fuel-rich condition. 2. The method of claim 1 wherein the oxide that inhibits the decrease in NOx storing ability of the NOx trap composition is selected from the group consisting of oxides of magnesium, oxides of manganese, and combinations thereof. 3. The method of claim 1 wherein the oxide that inhibits the decrease in NOx storing ability of the NOx trap composition is present in an amount from about 1 to 30% of the total weight of the NOx trap washcoat. 4. The method of claim 1 wherein the oxide that inhibits the decrease in NOx storing ability of the NOx trap composition is present in an amount from about 5 to 20% of the total weight of the NOx trap washcoat. 5. The method of claim 1 wherein the oxide that inhibits the decrease in NOx storing ability of the NOx trap composition is present in an amount from about 5 to 15% of the total weight of the NOx trap washcoat. 6. The method of claim 1 wherein the NOx absorber is selected from the group consisting of oxides of alkali metals, oxides of alkaline earth metals, oxides of rare earth metals, and combinations thereof. 7. The method of claim 1 wherein the NOx absorber is selected from the group consisting of cesium oxide, praseodymium oxide, strontium oxide, barium oxide, and combinations thereof. 8. The method of claim 1 wherein the precious metal is a metal selected from the group consisting of platinum, palladium, rhodium, and combinations thereof. 9. The method of claim 1 wherein the NOx trap composition is applied to a substrate. 10. The method of claim 9 wherein the substrate is cordierite. 11. The method of claim 9 wherein the NOx trap composition is applied to the substrate by washcoating. 12. A thermally stable NOx trap composition comprising: a support material; a NOx absorber material; an oxide selected from the group consisting of oxides of magnesium, oxides of manganese, and combinations thereof in sufficient contact with the NOx absorber that a NOx trap incorporating the NOx trap composition has a NOx storage efficiency of at least 5% at a temperature of 400째 C. after aging of the NOx trap, wherein proximity between oxidizing components and trapping components is optimized to maximize spillover; and a precious metal in contact with the NOx material. 13. The composition of claim 12 wherein the NOx absorber is selected from the group consisting of oxides of alkali metals, oxides of alkaline earth metals, oxides of rare earth metals, and combinations thereof. 14. The composition of claim 12 wherein the NOx absorber is selected from the group consisting of cesium oxide, praseodymium oxide, strontium, barium oxide, and combinations thereof. 15. The composition of claim 12 wherein the precious metal is a metal selected from the group consisting of platinum, palladium, rhodium, and combinations thereof. 16. The composition of claim 12 wherein the oxide is present in an amount from about 1 to 30% of the total weight of the NOx trap washcoat. 17. The composition of claim 12 applied to a substrate. 18. The composition of claim 17 wherein the substrate is cordierite. 19. A vehicle exhaust system comprising a NOx trap that includes the composition of claim 12. 20. A method of removing harmful gases from an automobile exhaust containing NOx, CO, and hydrocarbons the method comprising: contacting a NOx trap composition with a first exhaust gas mixture at a temperature of at least 200째 C., the first exhaust gas mixture comprising exhaust gases from an internal combustion engine operating in a fuel-lean condition and the NOx trap composition comprising: a precious metal; barium oxide; a oxide that inhibits the decrease in NOx storing ability of the barium oxide; and a support material, wherein proximity between oxidizing components and trapping components is optimized to maximize spillover; and contacting the NOx trap composition with a second exhaust gas composition, the second exhaust gas mixture comprising exhaust gases from an internal combustion engine operating in a fuel-rich condition.
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