Process for removal of high molecular weight impurities in the manufacture of purified terephthalic acid
US4782181A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 4, 1987 |
| Grant date | Nov 1, 1988 |
| Priority date | — |
| Expiry date | Jun 4, 2007 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C51/487
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for producing fiber grade terephthalic acid is disclosed. In this process impurities having high molecular weight are eliminated by hydrogenation comprising the following steps: (a) treating an aqueous solution containing at least about 1 percent of said impure terephthalic acid with hydrogen at a temperature in the range of about 300.degree. F. to about 450.degree. F. and at a pressure sufficient to maintain the solution in the liquid phase in the presence of a supported or unsupported metallic Group VIII noble metal catalyst wherein both the metal and support components are insoluble in the solution at the temperature and at a hydrogen partial pressure of from about 30 to about 300 pounds per square inch; (b) separating the treated solution from the catalyst; (c) crystallizing terephthalic acid from the separated solution while retaining impurities and the reduced aromatic compounds dissolved in the resulting mother liquor at a temperature in the range of about 100.degree. F. to about 450.degree. F.; and (d) separating the mother liquor as a liquid phase containing dissolved impurities and reduction products from said crystals while continuing to maintain a temperature …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.