The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 20, 1984
Filed:
Dec. 27, 1982
Lawrence G Packer, Lisle, IL (US);
Edward J Schlossmacher, PA, US;
Standard Oil Company (Indiana), Chicago, IL (US);
Abstract
Fiber-grade quality terephthalic acid can be obtained by dissolving partially purified terephthalic acid: the product separated from catalyst components and impurities in acetic acid solvent portion of oxidation effluent, acetic acid washed and dried: either in deionized water or acetic acid at temperatures from 250.degree. C. and upward, contacting the solution and hydrogen gas with a hydrogenation catalyst preferably a platinum family metal disposed on an insoluble support followed by separation of the solution from catalyst, cooling the separated solution to precipitate terephthalic acid, recovering, washing and drying the precipitate. The use of deionized water in the purification route, with respect to the oxidative preparation of terephthalic acid, has the drawback of maintaining two distinctly different solvent systems and tolerating the rather limited water solubility of the p-toluic acid. While the use of acetic acid as solvent in the purification route makes use of a solvent having a greater capacity to dissolve p-toluic acid (an oxidation co-product impurity and the reduction product of 4-carboxybenzaldehyde also a co-oxidation product), such use of acetic acid has the drawback of decreasing the hydrogenation rate as well as having some inherent decomposition of the acetic acid solvent. The aforementioned drawbacks are avoided by heating the oxidation effluent's suspension of impure solid terephthalic acid to a temperature of 250.degree. C. and upward in the presence of sufficient acetic acid to dissolve all the solids of the total solids content of said effluent, contacting such solution and hydrogen gas with the above platinum family hydrogenation catalyst, then precipitating, recovering, acetic acid washing, and drying terephthalic acid so purified. Such purification and recovery route also provides a less yellow purified product than that produced when the same process is conducted but in the absence of the platinum family metal hydrogenation catalyst.