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. 30, 2002
Filed:
Jun. 23, 2000
Masaaki Okuno, Himeji, JP;
Tsukasa Takahashi, Himeji, JP;
Nippon Shokubai Co., Ltd., Osaka-fu, JP;
Abstract
The invented process produces phthalic anhydride through gas-phase catalytic oxidation of ortho-xylene and/or naphthalene with an oxygen-containing gas using one or more fixed bed reactors. In the process, the gas-phase catalytic oxidation process is performed in three or more individual catalytic layers, and the conversion rates of ortho-xylene and/or naphthalene in the individual layers are controlled within specific ranges. The process is capable of providing phthalic anhydride in a high yield, is capable of minimizing deterioration of catalysts with time, and is capable of continuously stably producing phthalic anhydride in safety, even when a high concentration material gas is fed.