Recovery of nitric acid from nitration spent acid by toluene extraction
US4650912A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 26, 1985 |
| Grant date | Mar 17, 1987 |
| Priority date | — |
| Expiry date | Mar 26, 2005 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C201/16
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
In a method for denitrifying the nitric acid- and nitrous acid-containing spent acid phase from the nitration of an aromatic hydrocarbon by the mixed acid process which comprises forming a denitrification reaction medium by contacting the spent acid phase with an aromatic hydrocarbon under nitration reaction conditions to recover the nitric acid by the formation of a nitroaromatic hydrocarbon, the improvement which comprises PA0 (a) adding an amount of aromatic hydrocarbon which is slightly less than or equal to the stoichiometric amount necessary to deplete the spent acid phase of nitric acid, PA0 (b) photometrically monitoring the denitrification reaction medium for the appearance of a dark red to black color, and PA0 (c) upon detection of such color, adjusting the aromatic hydrocarbon:nitric acid molar ratio in the denitrification reaction medium to eliminate the color by reducing the aromatic hydrocarbon feed rate, or adding nitric acid to the denitrification reaction medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.