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:
Apr. 21, 1981
Filed:
May. 06, 1980
Makoto Komatsu, Kurashiki, JP;
Ryoichi Oda, Kurashiki, JP;
Mitsubishi Gas Chemical Company, Inc., Tokyo, JP;
Abstract
Crude terephthalic acid obtained by oxidation of p-tolualdehyde in a liquid phase with molecular oxygen in the presence of a bromine compound as a catalyst, using water as a solvent is purified by dissolving the crude terephthalic acid in water, hydrogenating the aqueous solution of terephthalic acid with molecular hydrogen in the presence of a hydrogenating catalyst, and recrystallizing the terephthalic acid from the hydrogenated aqueous solution, where an alkaline material such as a hydroxide, a carbonate, or a bicarbonate of sodium, potassium, calcium or barium is added to the aqueous solution of terephthalic acid to be purified before the hydrogenation. The purified terephthalic acid has a very low 4-CBA content, and no hydrogenation catalyst activity is lowered by the addition of the alkaline material.