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:
Nov. 11, 1980
Filed:
Oct. 05, 1979
Hobe Schroeder, Warrenville, IL (US);
David A Palmer, Naperville, IL (US);
Standard Oil Company (Indiana), Chicago, IL (US);
Abstract
Undesirable discoloration of resultant phthalic anhydride and decomposition thereof and/or o-phthalic acid accompanying dehydration of o-phthalic acid to its anhydride in the presence of oxidation catalyst components Co, Mn and Br can be avoided by the rapid dehydration of o-phthalic acid and rapid vaporization of its anhydride occurring at a reduced pressure of downward from 760 mm Hg down to 40 mm Hg and at a temperature of from 180.degree. C. up to 250.degree. C. under continuous flow conditions which permit rapid removal of anhydride as vapor stream from catalyst components remaining as part of a fluid residue.