Zirconia and sulfate in NOx traps to improved trapping and sulfur tolerance
US5753192A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 29, 1996 |
| Grant date | May 19, 1998 |
| Priority date | — |
| Expiry date | Nov 29, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/12
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
The invention is a nitrogen oxide trap comprising a porous support loaded with 6-15 wt. % strontium oxide and thereon, a mixture of: 0.5-5 wt. % precious metal catalyst selected from platinum, palladium, rhodium or mixtures thereof loaded, 3.5-15 wt. % zirconium and 15-30 wt. % sulfate, where preferably the ratio of zirconium to sulfate ranges from about 1:1 to 1:7; each wt. % being individually based on the weight of the support. The trap may be used in an internal combustion engine exhaust gas catalyst system. During lean-burn operation of the engine the trap sorbs nitrogen oxides (NOx) and releases the nitrogen oxides during decreased oxygen concentration in the exhaust gas, the desorbed NOx being converted to N.sub.2 and O.sub.2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.