| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for economically and stably producing high- quality acetic anhydride. SOLUTION: This method for producing purified acetic anhydride by distilling crude acetic anhydride in a distillation column 7 involves recycling the low- boiling fraction distilled off the distillation column 7 after ozone treatment thereof in an ozone treatment column 8. Since the acetic anhydride in the low- boiling fraction is recycled without being returned to a crude acetic anhydride production plant 1, returning of the acetic anhydride into ketene again or the like is suppressed, resulting in improving economy through suppressing acetic anhydride yield drop and/or energy loss. Further, unsaturated compounds contaminated in the low-boiling fraction are oxidized and gone by the above ozone treatment, and the concentrations of the unsaturated compounds affecting the hue of the final acetic anhydride is also prevented from rising in the distillation column 7, therefore the objective high-quality, purified acetic anhydride can be produced stably.
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