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:
Jan. 14, 1986
Filed:
Apr. 16, 1979
Haruhisa Yamamoto, Takaoka, JP;
Shinichi Akiyama, Takaoka, JP;
Nippon Zeon Co., Ltd., Tokyo, JP;
Abstract
In a process for preparing methacrylic acid by the vapor-phase catalytic oxidation of methacrolein or a methacrolein-containing mixture with molecular oxygen in the presence of an oxidation catalyst; the improvement wherein said process comprises a first-stage oxidation step of oxidizing methacrolein or a methacrolein-containing mixture as a starting material, a first-stage separating step of separating the resulting methacrylic acid from the reaction product obtained in the first-stage oxidation step, a second-stage oxidation step of oxidizing the mixture containing the unreacted methacrolein and obtained in the first-stage separating step, and a second-stage separating step of separating the resulting methacrylic acid from the reaction product obtained in the second-stage oxidation step, and with or without at least one additional oxidation step and separating step subsequent to the second-stage separating step, and wherein the conversion of methacrolein in the first-stage oxidation step is adjusted to 30-85 mole % and the final conversion of methacrolein is adjusted to at least 90 mole %.