Method of purifying acetic acid
AssigneeDaicel Chemical Industries, Ltd.
InventorsSatoshi Kimura, Takashi Ueno, Yoshiaki Morimoto
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Abstract
A method for purifying acetic acid containing at least one component selected from the group consisting of unsaturated compounds and carbonyl compounds as an impurity involves the step of purifying the acetic acid with a distillation column having at least 30 plates by operating the distillation column at a pressure ranging from 40 to 760 mmHg and a reflux ratio of at least 4, and yields a high-quality acetic acid which rates high in the potassium permanganate test without needing of the addition of any chemical to the acetic acid to be purified and a large amount of energy, and is economical.
Claims13
A method for purifying a crude acetic acid product mixture, which comprises the steps of:
- purifying a crude acetic acid product mixture containing at least one impurity selected from the group consisting of unsaturated compounds and carbonyl compounds in a first distillation column operated at atmospheric or an increased pressure and then purifying the mixture in a second distillation column having at least 30 plates and operated at a pressure ranging from 40 to 760 mmHg and a reflux ratio of at least four, wherein overhead vapor from the first column is used as the heat source for a reboiler of the second column and the pressure of the second column is less than the pressure of the first column.
In a method of purifying a crude acetic acid product mixture produced by reacting a mixture of methanol or methyl acetate and water or a mixture of methyl acetate, methanol and water and carbon monoxide in a reaction solvent comprising a rhodium catalyst, water, acetic acid and methyl iodide to form a crude acetic acid product mixture;
- the improvement comprising the steps of:
- purifying the crude acetic acid product mixture, in which is contained at least one impurity selected from the group consisting of unsaturated compounds and carbonyl compounds, in a first distillation column operating at atmospheric or an increased pressure and then purifying the crude acetic acid product mixture in a second distillation column comprising at least 30 plates and operated at a pressure ranging from 40 to 760 mmHg and a reflux ratio of at least 4, wherein overhead vapor from the first column is used as the heat source for a reboiler of the second column and the pressure of the second column is lower than the pressure of the first column.
Dependencies are inferred from the claim text.