Abstract: In one embodiment, the invention is to a process for purifying acetic anhydride. The process includes the steps of feeding a liquid crude acetic anhydride stream directly to a distillation column and separating the liquid crude acetic anhydride stream to produce a light ends stream, a sidedraw and a residue stream. The sidedraw comprises substantially pure acetic anhydride product. The distillation column is operated at a pressure less than 101 kPa. The substantially pure acetic anhydride product comprises greater than 98 wt. % acetic anhydride, has a permanganate time of greater than 10 minutes, and has an APHA color of less than 10.

Abstract: In one embodiment, the invention is to a process for purifying acetic anhydride. The process includes the steps of feeding a liquid crude acetic anhydride stream directly to a distillation column and separating the liquid crude acetic anhydride stream to produce a light ends stream, a sidedraw and a residue stream. The sidedraw comprises substantially pure acetic anhydride product. The distillation column is operated at a pressure less than 101 kPa. The substantially pure acetic anhydride product comprises greater than 98 wt. % acetic anhydride, has a permanganate time of greater than 10 minutes, and has an APHA color of less than 10.

Abstract: In one embodiment, the invention is to a process for producing acetic anhydride. The process includes at least a step of carbonylating methanol and/or a methanol derivative with carbon monoxide to form acetic acid, and contacting ketene with the acetic acid to form a crude acetic anhydride product stream and a vent stream having unreacted ketene. The process further comprises a step of directing at least a portion of the vent stream to a liquid ring vacuum compressor having a ring seal fluid comprising acetic acid The unreacted ketene in the portion of the vent stream contacts the ring seal fluid to form supplemental acetic anhydride.

Abstract: In one embodiment, the invention is to a process for producing acetic anhydride. The process includes at least a step of carbonylating methanol and/or a methanol derivative with carbon monoxide to form acetic acid, and contacting ketene with the acetic acid to form a crude acetic anhydride product stream and a vent stream having unreacted ketene. The process further comprises a step of directing at least a portion of the vent stream to a liquid ring vacuum compressor having a ring seal fluid comprising acetic acid The unreacted ketene in the portion of the vent stream contacts the ring seal fluid to form supplemental acetic anhydride.