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:
Aug. 18, 1981
Filed:
Sep. 22, 1978
Norbert Schenk, Leverkusen, DE;
Jorg Krekel, Essen, DE;
Paul Losacker, Leichlingen, DE;
Wolfgang Swodenk, Odenthal-Gloebusch, DE;
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
In the preparation of anthraquinone by reacting a mixture containing naphthalene, phthalic anhydride and tetrahydroanthraquinone with oxygen at elevated temperature while simultaneously separating off at least part of the naphthalene, the improvement which comprises supplying the naphthalene, phthalic anhydride and tetrahydroanthraquinone to a distillation system which consists of a column having a rectifying section, a stripping section and a boiler, at least one of the stripping section and the boiler being designed so that rapid through-passage of the feed mixture is prevented. Downcomers in the stripping section maintain liquid levels on the trays of about 5 to 500 mm and the boiler may have several successive chambers to provide the desired residence time in the system. A liquid mixture of naphthalene, phthalic anhydride and anthraquinone is removed from the boiler while a gas mixture including naphthalene is taken off from the rectifying section, being cooled to condense naphthalene for use in oxidation to naphthoquinone and phthalic anhydride.