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. 02, 1982
Filed:
Apr. 23, 1980
Raymond M Cahen, Brussels, BE;
Labofina S.A., Brussels, BE;
Abstract
A process for purifying crude terephthalic acid is disclosed which comprises treating a solution of crude terephthalic acid in an aqueous solution of a water-soluble heavy metal salt wherein the heavy metal is cobalt, manganese, iron or nickel under elevated pressure and at elevated temperature in the presence of a supported noble metal catalyst with nitrogen gas or a gas-mixture of nitrogen and hydrogen. The treated solution is then separated from the catalyst and purified crystalline terephthalic acid is recovered by crystallization and separation from the mother liquor wherein impurities and the heavy metal salts are retained. The process is especially useful for directly treating crude terephthalic acid obtained in an oxidation process in the presence of a heavy-metal-salt-catalyst.