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:
May. 13, 1980
Filed:
Jan. 10, 1978
Ryo Matsuura, Yamato, JP;
Tatsuyoshi Komatsu, Kamakura, JP;
Yukio Nomiyama, Yokohama, JP;
Kenji Usui, Nihonbashi, JP;
Kawasaki Kasei Chemicals Limited, Tokyo, JP;
Abstract
In a process for separation of naphthoquinone and phthalic acid from an aqueous slurry prepared by contacting a reaction mixture gas formed by a catalytic vapor phase oxidation of naphthalene with an aqueous medium, the decomposition of naphthoquinone is prevented and phthalic acid is substantially separated by adding a base to the aqueous slurry so as to neutralize only sulfuric acid component and maleic acid component without substantially neutralizing phthalic acid component and heating the aqueous slurry to dissolve phthalic acid to form a slurry of naphthoquinone in an aqueous solution of phthalic acid and extracting naphthoquinone with a solvent while preventing a crystallization of phthalic acid. A pH of the aqueous slurry is adjusted in a range of 1.2 to 2.5 before the heat dissolution of phthalic acid and the extraction of naphthoquinone. An aqueous phase obtained after the extraction of naphthoquinone is cooled to crystallize phthalic acid and then the filtrate separating from the resulting slurry is used as an aqueous medium for contacting with the reaction mixture gas, optionally after adjusting pH in a range of 1.2 to 2.5.