Separation of methanol and propylene oxide from a reaction mixture
AssigneeArco Chemical Technology, L.P.
InventorsMichael A. Rueter, John C. Jubin, Jr.
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Abstract
Propylene is separated from the methanol present as a solvent in a crude olefin epoxidation product by means of an extractive distillation wherein a relatively heavy polar solvent having hydroxy groups such as water or propylene glycol is used as the extractive solvent. The method is also useful for removing water and impurities such as acetaldehyde from the propylene oxide.
Claims18
A method of purifying a crude epoxidation reaction product comprised of 2 to 10 weight percent of propylene oxide, 50 to 80 weight percent methanol and 10 to 30 weight percent water, said method comprising the steps of:
- (a) introducing the crude epoxidation reaction product into an intermediate section of an extractive distillation zone;
- (b) introducing a polar solvent having a hydroxy functionality and a boiling point higher than that of methanol into an upper section of said extractive distillation zone;
- (c) distilling propylene oxide overhead from said extractive distillation zone;
- and
- (d) recovering a bottoms stream comprised of methanol and the polar solvent from a lower section of said extractive distillation zone.
A method of purifying a crude epoxidation reaction product comprised of 2 to 10 weight percent propylene oxide, 50 to 85 weight percent methanol and 10 to 30 weight percent water, said method comprising the steps of:
- (a) introducing the crude epoxidation reaction product into an intermediate section of an extractive distillation zone containing from 20 to 60 theoretical plates at a point which is from 40 to 70% of the distance in theoretical plates from the bottom to the top of the extractive distillation zone;
- (b) introducing a polar solvent selected from the group consisting of water, glycols, glycol ethers and mixtures thereof into an upper section of said extractive distillation zone, in an amount which is at least 5 percent by weight of the crude epoxidation reaction product;
- (c) distilling propylene oxide overhead from said extractive distillation zone, wherein the propylene oxide so distilled contains less than 0.05 weight percent water and less than 0.2 weight percent methanol;
- and
- (d) recovering a bottoms stream comprised of methanol and the polar solvent from a lower section of said extractive distillation zone.
Dependencies are inferred from the claim text.