Purification of crude terephthalic acid
US4892972A · kind A · utility
47Cited by
7References
30Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Apr 27, 1989 |
| Grant date | Jan 9, 1990 |
| Priority date | — |
| Expiry date | Apr 27, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C51/487
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Aqueous solutions of crude terephthalic acid are purified by hydrogenation in the presence of plural noble metal catalysts in separate layers. Initially, the solution to be purified is passed through a layer of ruthenium-on-carbon catalyst, rhodium-on-carbon catalyst, or platinum-on-carbon catalyst, and thereafter through a layer of palladium-on-carbon catalyst. Optionally, the purified aqueous terephthalic acid solution can be treated further to decrease the 4-carboxybenzaldehyde content thereof by passing it through a layer of rhodium-on-carbon catalyst downstream from the palladium-on-carbon catalyst layer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.