| 摘要 |
In the prodn. of an aq. soln. of methacrylic acid by the catalytic gas-phase oxidn. of isobutylene, tert. BuOH or methacrolein and cooling the methacrylic acid-contg. reaction prod. gas in 2 or several cooling towers, the methacrylic acid is recovered by: (a) collecting a pt. of the methacrylic acid, a small pt. of AcOH and all by-prods. having a b.pt. higher than that of methacrylic acid, in a 1st tower; (b) collecting the remaining methacrylic acid and a large pt. of the AcOH in the 2nd and following towers, (c) extracting the condensates in the 1st tower with an aliphatic, alicyclic or aromatic hydrocarbon having a b.pt. below 150 deg.C, alone or in combination with one another, (d) extracting the condensate in the 2nd and following towers with an ester, ketone or ether having a b.pt. below 150 deg.C alone or in combination with one another, and (e) distilling the extracts to recover methacrylic acid.
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