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. 28, 2000
Filed:
Mar. 16, 1999
Nippon Shokubai Co Ltd, Osaka, JP;
Abstract
Provided is a process for producing pyromellitic dianhydride by feeding 1,2,4,5-tetraalkylbenzene to a fixed bed multitubular type reactor charged with a catalyst layer to carry out catalytic vapor phase oxidation. This process is characterized by dividing the catalyst layer into at least two layers to charge a layer at an outlet side of reaction gas and a layer at an inlet side of raw material mixed gas with the following catalyst A and catalyst B respectively or dividing the catalyst layer into at least three layers to charge a layer at an outlet side of reaction gas, an intermediate layer and a layer at an inlet side of raw material mixed gas with the following catalyst A, catalyst B and catalyst C respectively: