Removal of acetals from process streams
AssigneeCelanese International Corporation
InventorsDavid Lee, Yaw-Hwa Liu, Ronald D. Shaver
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Abstract
A process for producing acetic acid is provided that is capable of lowering acetaldehyde mass composition in acetic acid. The process for producing acetic acid according to the present invention comprises at least one distillation step that satisfies the following operating conditions (i) temperature in a lower portion of the distillation column is not less than 40° C.; (ii) water mass composition in the lower stream is not less than 0.3 wt. %; or (iii) acetic acid mass composition in the lower stream on weight percentage basis is greater than the acetic acid mass composition in the first mixture; wherein the methanol mass composition in the first mixture is less than or equal to 2 wt. %.
Claims20
A process for separating acetaldehyde from a first mixture comprising acetaldehyde, one or more C1-C12 alkyl iodides, water, and methanol, the process comprising the steps of:
- distilling the first mixture in a distillation column to form at least two streams selected from the group consisting of an overhead stream, sidecut stream, and lower stream, wherein either the overhead stream or sidecut stream are withdrawn as a second mixture;
- separating acetaldehyde from the second mixture;
- and
- controlling a 1,1-dimethoxyethane mass composition in the lower stream to less than or equal to 0.03 wt. % by operating the distillation column under at least one of the following conditions (i) to (iii):
- (i) temperature in a lower portion of the distillation column is not less than 40° C.;
- (ii) water mass composition in the lower stream is not less than 0.3 wt. %;
- or
- (iii) acetic acid mass composition in the lower stream on weight percentage basis is greater than the acetic acid mass composition in the first mixture;
- wherein a methanol mass composition in the first mixture is less than or equal to 2 wt. %;
- and
- wherein the water to acetic acid ratio in the lower stream is from 1:10 to 1:100.
A process for separating acetaldehyde from a first mixture comprising acetaldehyde, one or more C1-C12 alkyl iodides, water, and methanol, the process comprising the steps of:
- distilling the first mixture in a distillation column to form at least two streams selected from the group consisting of an overhead stream, sidecut stream, and lower stream, wherein the sidecut stream is withdrawn as a second mixture;
- separating the second mixture into an aqueous stream comprising acetaldehyde or an organic stream comprising the one or more C1-C12 alkyl iodides;
- and
- controlling a 1,1-dimethoxyethane mass composition in the lower stream to less than or equal to 0.03 wt. % by operating the distillation column under at least one of the following conditions (i) to (iii):
- (i) temperature in a lower portion of the distillation column is not less than 40° C.;
- (ii) water mass composition in the lower stream is not less than 0.3 wt. %;
- or
- (iii) acetic acid mass composition in the lower stream on weight percentage basis is greater than the acetic acid mass composition in the first mixture;
- wherein the water to acetic acid ratio in the lower stream is from 1:10 to 1:100;
- and
- wherein a methanol mass composition in the first mixture is less than or equal to 2 wt. %.
Dependencies are inferred from the claim text.