Method for cleaning exhaust gas from an internal combustion engine
US6883305B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 14, 2000 |
| Grant date | Apr 26, 2005 |
| Priority date | — |
| Expiry date | Jan 14, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/12
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
In a method and apparatus for removing nitrogen oxides from the exhaust gas of a lean-burn automobile, a CO adsorbent component, which may, for example be made of Pd, Ru or Ir, is contained in an exhaust gas cleaning catalyst which captures NOx when the air-fuel ratio of exhaust gas is higher than theoretical air-fuel ratio, and reduces the captured NOx when the air-fuel ratio of exhaust gad is less than or equal to the theoretical air-fuel ratio. The catalyst, which includes Rh, Pt, and element selected from among the alkaline and alkaline earth metals (Na, Mg, K, Li, Cs, Sr and Ca), and a CO adsorbent material comprising Pd, Ir or Ru, has a CO desorption capacity that reaches at maximum level at a temperature within the range from 200 to 220° C. when its temperature is increased in a He gas flow at the rate of 5 to 10° C./min, after said catalyst is saturated at 100° C. Exhaust gas having an air-fuel ratio higher than theoretical air-fuel and exhaust gas having an air-fuel ratio less than or equal to the theoretical air-fuel ratio are alternately made to flow to the catalyst.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.