Separating and removing impurities from tetrafluoroethanes by using extractive distillation
AssigneeE. I. Du Pont de Nemours and Company
InventorsBarry A. Mahler, Ralph N. Miller
Life of this patent
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Abstract
The disclosure relates to separating 1,1,2,2 tetrafluoroethane (HFC-134) and 1,1,1,2 tetrafluoroethane (HFC-134a) from each other and/or from fluorocarbon impurities by using extractive distillation with an extractive agent comprising an alcohol. Examples of suitable extractive agents comprise at least one member from the group of methanol, butanol, ethanol, propanol, their isomers and cyclic compounds thereof, among others.
Claims15
A process for purifying tetrafluoroethane isomers in a first mixture comprising [HFC-134, HFC- 134a]1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane and fluorocarbon impurities, the process comprising the steps of:
- adding at least one extractive agent comprised of at least one alcohol to the first mixture in order to form a second mixture:
- separating at least one fluorocarbon impurity from the tetrafluoroethane isomers in the second mixture by extractively distilling the second mixture in an extractive distillation zone,
- thereby optionally forming a third mixture comprising the extractive agent and fluorocarbon impurities and separating the extractive agent from the third mixture, and;
- recovering at least one tetrafluoroethane isomer [that is substantially free of fluorocarbon impurities.]
A process for separating tetrafluoroethane isomers in a first mixture comprising [1,1,1,2-tetrafluoroethane ]1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane and fluorocarbon impurities, the process comprising the steps of:
- adding at least one extractive agent comprised of at least one alcohol to the first mixture in order to form a second mixture;
- separating 1,1,1,2-tetrafluoroethane from the 1,1,2,2-tetrafluoroethane in the second mixture by extractively distilling the second mixture in an extractive distillation zone and thereby recovering 1,1,2,2-tetrafluoroethane and forming a third mixture comprising the extractive agent, 1,1,1,2-tetrafluoroethane and fluorocarbon impurities;
- and,
- optionally separating the 1,1,2,2-tetrafluoroethane from the third mixture.
A process for making purified tetrafluoroethane isomers from a first mixture comprising [HFC-134a, HFC-134]1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane and fluorocarbon impurities, the process comprising the steps of:
- adding at least one extractive agent to the first mixture in order to form a second mixture;
- separating substantially only one of the isomers from the other isomer and the fluorocarbon impurities in the second mixture by extractively distilling the second mixture in an extractive distillation zone and thereby recovering a separated isomer [that is substantially pure and substantially free of the other isomer], and;
- optionally forming a third mixture comprising the extractive agent, fluorocarbon impurities and one isomer in the bottom stream.
A process for separating tetrafluoroethane isomers in a first mixture comprising [HFC-134, HFC-134a]1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane and fluorocarbon impurities, the process comprising the steps of:
- adding at least one extractive agent comprised of at least one alcohol to the first mixture in order to form a second mixture;
- separating [HFC-134a]1,1,1,2-tetrafluoroethane from the [HF C-134] 1,1,2,2-tetrafluoroethane in the second mixture by extractively distilling in an extractive distillation zone, thereby forming a third mixture comprising the extractive agent, [HFC-134]1,1,2,2-tetrafluoroethane substantially free of [HFC-134a]1,1,1,2-tetrafluoroethane, and fluorocarbon impurities;
- and,
- optionally separating the [HFC-134]1,1,2,2-tetrafluoroethane from the third mixture.
Dependencies are inferred from the claim text.