Reduction of toxic substances in waste gas emissions
US6197268A · kind A · utility
18Cited by
9References
14Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 2, 1999 |
| Grant date | Mar 6, 2001 |
| Priority date | — |
| Expiry date | Jul 2, 2019 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01D53/75
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
Nitrogen oxides are removed from a waste gas stream by contacting the waste gas stream with ammonia, thereby reducing the nitrogen oxides to nitrogen. Residual nitrogen oxides and unreacted ammonia in the waste gas stream leaving the nitrogen oxides reducing step are oxidized to nitrogen pentoxide or nitric acid by contacting this gas stream with ozone. Contact of the ozone and waste gas is preferably carried out in the presence of an aqueous solution at a pH above about 9 and at a temperature above about 75.degree. C., and this step is preferably carried out in the presence of an ammonia-oxidizing catalyst.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.