| 摘要 |
PROBLEM TO BE SOLVED: To efficiently and stably recovering acrylic acid from an acrylic acid fraction containing acrylic acid dimer and maleic acid and from a high boiling point impurity separating column, in a process for producing acrylic acid through a catalytic gas phase oxidizing step for acrylic acid containing acrylic acid dimer and maleic acid, especially propylene and/or acrolein, a collecting step for collecting acrylic acid as an acrylic acid aqueous solution, an azeotropic separation step for recovering acrylic acid from the acrylic acid aqueous solution by azeotropic distillation, and a purifying step comprising a high boiling point impurity separating column for removing high boiling point impurities by distilling crude acrylic acid obtained from the azeotropic separation step. SOLUTION: The acrylic acid fraction containing acrylic dimer and maleic acid is introduced to a distillation column having a thin layer evaporator, the acrylic acid is recovered therein by distilling from the overhead of the column, the bottom product from the thin layer evaporator is introduced to a thermally decomposing vessel and the acrylic acid dimer is thermally decomposed herein. COPYRIGHT: (C)2007,JPO&INPIT
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