Process for continuously producing anhydrous sodium dithionite
US4081521A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 5, 1976 |
| Grant date | Mar 28, 1978 |
| Priority date | — |
| Expiry date | May 5, 1996 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B17/66
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A process for continuously producing anhydrous sodium dithionite in the form of large granules which comprises reacting formic acid, sodium formate, sodium hydroxide and sulfurous acid anhydride in hydrous methanol using a multi-stage reaction apparatus, wherein all the required amounts of the formic acid or sodium formate, sodium hydroxide, methanol and water, and at least 60%, based on the required amount, of sulfurous acid anhydride are introduced into a first reactor, and the residence time in the first reactor is adjusted so that the conversion of the sulfurous acid anhydride to anhydrous sodium dithionite is within the range of 25 to 50%; the remainder of the sulfurous acid anhydride is introduced into a second reactor; and the reaction temperature in any given reactor is maintained at a point not lower than the reaction temperature in the immediately preceding reactor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.