Method for controlling NOx reduction system
US8186149B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 30, 2007 |
| Grant date | May 29, 2012 |
| Priority date | — |
| Expiry date | Mar 30, 2029 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/12
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A NOx reduction system comprises NOx treatment catalyst and air-fuel ratio control switch for changing the air-fuel ratio of an exhaust gas to a lean or rich state. The NOx treatment catalyst comprises at least a first catalyst layer containing a solid acid catalyst capable of adsorbing ammonia and a second catalyst layer containing a noble metal and a cerium oxide material. The second and the first catalyst layer are stacked in that order on a carrier, and the first catalyst layer constitutes the uppermost layer. NOx is passed through the first catalyst layer in the lean state and is temporarily stored in the second catalyst layer. Thereafter, in the rich state, NOx is converted to NH3 and is restored in the first catalyst layer. When the state is again returned to the lean state, NH3 is converted to nitrogen which is finally released from the first catalyst layer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.