Processes for purifying acetic acid and hydrating anhydride
AssigneeCelanese International Corporation
InventorsRonald D. SHAVER, Yaw-Hwa LIU, Mark O. SCATES
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Abstract
Processes for purifying acetic acid by distilling a process stream in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.
Claims21
1-20. (canceled)
A process for producing acetic acid comprising:
- a. carbonylating, in a reactor, at least one member selected from the group consisting of methanol, dimethyl ether, and methyl acetate in a reaction medium comprising water at a concentration from 0.1 to 14 wt. %, a rhodium catalyst, methyl iodide, and an iodide salt;
- b. separating the reaction medium to form a liquid recycle stream and a vapor product stream;
- c. distilling at least a portion of the vapor product stream in a first column and withdrawing a side stream from a location of the first column having more than 0.2 wt. % water;
- d. distilling the side stream in a second column to obtain a product stream and withdrawing the product stream from a location of the second column having less than 0.2 wt. % water;
- and
- e. contacting the product stream with a cation exchange resin to form a purified acetic acid product.
Dependencies are inferred from the claim text.