| 摘要 |
Process for the recovery of methacrylic acid during the preparation of an aqueous solution of methacrylic acid, in which the methacrylic acid-containing reaction product gas obtained in the gas-phase oxidation of isobutylene, t-butanol or methacrolein by means of a catalyst is cooled in two or more multiple-stage cooling towers, which is characterised in that a part of the methacrylic acid, a small part of acetic acid and essentially all the by-products having a boiling point higher than that of methacrylic acid are collected in the first tower, the remaining methacrylic acid and a large part of the acetic acid are collected in the second and the following towers, the condensate in the first tower is extracted with an aliphatic, alicyclic or aromatic hydrocarbon having a lower boiling point than 150 DEG C, on its own or in combination with one another, the condensate in the second and the following towers is extracted with an ester, ketone or ether having a boiling point lower than 150 DEG C, on its own or in combination with one another, and these extracts are distilled to recover methacrylic acid.
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