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:
Jul. 20, 1993
Filed:
Oct. 23, 1992
Kenji Ueda, Hyogo, JP;
Masaaki Okuno, Hyogo, JP;
Tatsuya Kawabata, Hyogo, JP;
Shinya Tanaka, Hyogo, JP;
Nippon Shokubai Co., Ltd., Osaka, JP;
Abstract
The production of phthalic anhydride by the catalytic vapor-phase oxidation of a mixture of ortho-xylene and naphthalene is accomplished advantageously by a method which comprises packing in a reaction vessel, as a former-stage catalyst, a catalyst produced by supporting on an inactive carrier a catalytic substance composed of vanadium oxide and a specific anatase type titanium dioxide, Nb, P, Sb, and at least one component selected from the group consisting of K, Cs, Rb, and Tl as oxide and, as a latter-stage catalyst, a catalyst similar to the former-stage catalyst excepting the amount of the at least one component selected from among K, Cs, Rb, and Tl is in the range between 17 and 63% by weight as an oxide based on the amount of the same component used in the former-stage catalyst, both in specified bed heights feeding to this reaction vessel the mixture of ortho-xylene and naphthalene and a molecular oxygen-containing gas at a temperature in the range between 300.degree. and 450 .degree. C.