Purification process of methacrylic acid

摘要

A process is provided for the purification of methacrylic acid. The process can easily remove dibasic acids and aldehydes containing in trace amounts as impurities. According to the process, crude methacrylic acid obtained as an aqueous solution by vapor-phase catalytic oxidation of isobutylene, tertiary butanol, methacrolein or isobutyl aldehyde is treated with at least one compound selected from the group consisting of m-aminophenol, m-phenylenediamine, 2,4-diaminotoluene and 2,4-diamino-diphenylamine, followed by distillation, optionally, in the presence of a p-phenylene diamine.