Removal and recovery of nitrogen and sulfur oxides from gaseous mixtures containing them
US4425313A · kind A · utility
Inventor
Key dates
| Filing date | Oct 15, 1981 |
| Grant date | Jan 10, 1984 |
| Priority date | — |
| Expiry date | Oct 15, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A50/20
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A cyclic process for removing lower valence nitrogen oxides from gaseous mixtures includes treating the mixtures with an aqueous media including alkali metal carbonate and alkali metal bicarbonate and a preoxygen oxidant to form higher valence nitrogen oxides and to capture these oxides as alkali metal salts, expecially nitrites and nitrates, in a carbonate/bicarbonate-containing product aqueous media. Highly selective recovery of nitrates in high purity and yield may then follow, as by crystallization, with the carbonate and bicarbonate alkali metal salts strongly increasing the selectivity and yield of nitrates. The product nitrites are converted to nitrates by oxidation after lowering the product aqueous media pH to below about 9. A cyclic process for removing sulfur oxides from gas mixtures includes treating these mixtures with aqueous media including alkali metal carbonate and alkali metal bicarbonate where the ratio of alkali metal to sulfur dioxide is not less than 2. The sulfur values may be recovered from the resulting carbonate/bicarbonate/sulfite containing product aqueous media as alkali metal sulfate or sulfite salts which are removed by crystallization from the carbon…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.