Modified platinum NOx trap for automotive emission reduction
US6537511B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 21, 2000 |
| Grant date | Mar 25, 2003 |
| Priority date | — |
| Expiry date | Sep 24, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/12
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
The invention is a method of treating exhaust gases generated by an internal combustion engine using a NOx trap in the exhaust flow system. The method comprises locating a nitrogen oxide trap in the exhaust gas passage and cycling the air/fuel ratio of the exhaust gases entering the trap between lean and rich, such that the trap absorbs nitrogen oxides during the lean cycle and desorbs the nitrogen oxides when the concentration of the oxygen in the exhaust flow is lowered as during a rich cycle. The trap comprises: (a) a porous support material comprising mostly &ggr;-alumina; (b) a sulfur-suppressing metal selected from the group consisting of cesium, zinc and a combination of cesium and zinc; (c) a precious metal; and (d) a NOx sorption metal such as barium, the metals being deposited in the support material, the amount of the metals being individually dependent on the weight of the support material. The desorbed nitrogen oxides may be converted over the precious metal to N2 by reductants like hydrogen, hydrocarbon and carbon monoxide present in the exhaust gas.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.