| 摘要 |
PURPOSE:To recover advantageously acetic anhydride from an equeous solution containing the acetic anhydride and acetic acid, by using a specific mixture containing an organic solvent as an extractant, having high distribution ratio and selectivity and low mutual solubility in water, and capable of being easily purified after extraction. CONSTITUTION:Acetic acid is thermally decomposed, and the decomposition gas is cooled to produce ketene. In the process, an aqueous solution which is a condensate obtained in the cooling step of the decomposition gas and contains acetic anhydride and acetic acid is brought into contact with one or two or more solvents selected from hydrophobic organic solvents and ketones or esters as an extractant to extract and recover the acetic anhydride. Specific examples of the extractant include heptane, nonane and cyclopentane, etc. An agitation extractor such as mixer-settler type or column type extractor is preferred for the extractor. Operating conditions are preferably as follows; 0.2-1.5wt. ratio between the extracting solvent and the extraction raw material and 20-50 deg.C extraction temperature.
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