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. 01, 1986
Filed:
Mar. 28, 1985
Applicant:
Inventor:
Helmut Scharf, Schermbeck, DE;
Assignee:
Chemische Werke Huls Aktiengesellschaft, Marl, DE;
Primary Examiner:
Int. Cl.
CPC ...
C07D / ;
U.S. Cl.
CPC ...
549239 ;
Abstract
A method of separating pyromellitic acid dianhydride from the reaction gas obtained from the gas phase oxidation of 1,2,4,5-tetraalkylbenzene with an oxygen bearing gas in a closed gas circulatory system, comprising, (a) desublimating pyromellitic acid dianhydride by contacting the product gas obtained from said gas phase oxidation reaction with a cold, oxygen bearing gas, (b) catalytically burning the byproducts in the waste gas obtained from the desublimation step, and (c) recirculating a proportionate amount of the byproduct free waste gas to the oxidation reactor for the gas phase oxidation reaction.