WO2000044697A1 - Separation of ethanol and water from mixtures thereof by extractive distillation - Google Patents
Separation of ethanol and water from mixtures thereof by extractive distillation Download PDFInfo
- Publication number
- WO2000044697A1 WO2000044697A1 PCT/IB2000/000076 IB0000076W WO0044697A1 WO 2000044697 A1 WO2000044697 A1 WO 2000044697A1 IB 0000076 W IB0000076 W IB 0000076W WO 0044697 A1 WO0044697 A1 WO 0044697A1
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- WO
- WIPO (PCT)
- Prior art keywords
- ethanol
- extractive distillation
- water
- separation
- mixture
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
- C07C29/84—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation by extractive distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
- B01D3/40—Extractive distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/42—Regulation; Control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
- B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
- B01D5/006—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with evaporation or distillation
- B01D5/0063—Reflux condensation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
Definitions
- the present invention relates to the separation of ethanol and water from mixtures thereof by extractive distillation.
- Extractive distillation is a process to separate close-boiling compounds from each other by introducing a selectively-acting third component, the extractive distillation solvent, with the result that the relative volatility of the mixture to be separated is increased and azeotropes, if present, are overcome.
- the extractive distillation solvent is to be selected such that it does not form an undesired azeotrope with any of the compounds in the mixture.
- azeotrope The separation of ethanol and water is complicated due to the existence of an azeotrope.
- Azeotropic distillation using benzene or cyclohexane is commonly used to effect the separation.
- Membrane separation, such as pe ⁇ /aporation, may alternatively be used to break the azeotrope.
- Pressure swing distillation is another separation method that may be used to produce pure ethanol and pure water. All of these methods utilize two distillation columns. In the case of azeotropic distillation, a phase separation device is needed. In the case of membrane separation, membrane modules are needed. Extractive distillation can also be used to effect the desired separation. This method also uses a two column system but the operation is simple. Ethylene glycol has been proposed in the literature as an extractive distillation solvent for the system ethanol/water.
- extractive distillation is the method of separating close boiling compounds from each other by carrying out the distillation in a multiplate rectification column in the presence of an added liquid or liquid mixture, said liquid(s) having a boiling point higher than the compounds being separated.
- the extractive distillation solvent is introduced near the top of the column and flows downward until it reaches the stillpot or reboiler. Its presence on each plate of the rectification column alters the relative volatility of the close boiling compounds in a direction to make the separation on each plate greater and thus require either fewer plates to effect the same separation or make possible a greater degree of separation with the same number of plates.
- the extractive distillation solvent should boil higher than any of the close boiling liquids being separated and not form minimum azeotropes with them. Usually the extractive distillation solvent is introduced a few plates from the top of the column to ensure that none of the extractive distillation solvent is carried over with the lowest boiling component.
- a method of separation of ethanol and water includes the step of distilling a mixture of ethanol / water containing at least ethanol and water by way of an extractive distillation process in the presence of an extractive distillation solvent selected from the group consisting of an amine and a chlorinated hydrocarbon.
- the ethanol / water mixture may contain only ethanol and water.
- the amine may be diaminobutane.
- the amine may be 1 ,3-diaminopentane.
- the amine may be diethylene triamine.
- the chlorinated hydrocarbon may be hexachlorobutadiene.
- vapour-liquid equilibrium still 10 including a bulb flask 12 having a tube 14 leading to a condenser 16 and terminating in an outlet 18.
- the outlet 18 has an electromagnetic closure mechanism 20.
- a liquid phase sample conduit 22 leads into the flask 12.
- a further liquid phase sample conduit 24 leads into the tube 14.
- a first thermometer 26 is adapted to read the temperature of the liquid contained in the flask 12, and a second thermometer 28 is adapted to read the temperature of the vapour in the tube 14.
- the flask 12 can be heated by a heating mantle 30.
- the extractive distillation procedure is as follows:
- a liquid mixture is prepared consisting of ethanol, water and an extractive distillation solvent.
- the liquid is introduced into the bulb flask 12 via conduit 22.
- the mixture in the bulb flask 12 is then heated by the heating mantle 30 and kept at boiling point.
- the mixture separates into a liquid phase remaining in the bulb flask 12 and a vapour phase in the tube 14.
- the vapour phase is cooled by the condenser 16, whereafter it condenses and returns as liquid to the bulb flask 12.
- the mixture is boiled and condensed for several hours, normally 5 to 6 hours. The process of evaporation and condensation is repeated until equilibrium is reached between the vapour and liquid phases. Thereafter, a liquid sample of the liquid phase in the bulb flask 12 is extracted through conduit 22 and a liquid sample of the condensed vapour phase in the tube 14 is extracted through conduit 24.
- thermometer 26 The temperature of the liquid phase in the bulb flask 12 is continuously monitored by the thermometer 26, and the temperature of the vapour phase in the tube 14 is continuously monitored by the thermometer 28.
- An ethanol/water liquid mixture with a molar ratio of 1.25:1 has a relative volatility of 1.71.
- the separation was effected by using a suitable amine as an extractive distillation solvent.
- An ethanol/water liquid mixture with a molar ratio of 4:1 has a relative volatility of 1.12.
- the separation was effected by using a suitable amine as an extractive distillation solvent.
- An ethanol/water mixture with a molar ratio of 0.9:1 has a relative volatility of 2.07.
- the separation was effected by using a suitable chlorinated hydrocarbon as an extractive distillation solvent.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
Extractive distillation is a process to separate close-boiling compounds from each other by introducing a selectively-acting third component, the extractive distillation solvent, with the result that the relative volatility of the mixture to be separated is increased and azeotropes, if present, are overcome. The extractive distillation solvent is to be selected such that it does not form an undesired azeotrope with any of the compounds in the mixture. The invention suggests a method of separation of ethanol and water by distilling a mixture of ethanol/water by way of an extractive distillation process in the presence of an extractive distillation solvent selected from the group consisting of an amine and a chlorinated hydrocarbon.
Description
Separation of ethanol and water from mixtures thereof by extractive distillation.
FIELD OF INVENTION
The present invention relates to the separation of ethanol and water from mixtures thereof by extractive distillation.
BACKGROUND TO INVENTION
Extractive distillation is a process to separate close-boiling compounds from each other by introducing a selectively-acting third component, the extractive distillation solvent, with the result that the relative volatility of the mixture to be separated is increased and azeotropes, if present, are overcome. The extractive distillation solvent is to be selected such that it does not form an undesired azeotrope with any of the compounds in the mixture.
The separation of ethanol and water is complicated due to the existence of an azeotrope. Azeotropic distillation using benzene or cyclohexane is commonly used to effect the separation. Membrane separation, such as peπ/aporation, may alternatively be used to break the azeotrope.
Pressure swing distillation is another separation method that may be used to produce pure ethanol and pure water. All of these methods utilize two distillation columns. In the case of azeotropic distillation, a phase separation device is needed. In the case of membrane separation, membrane modules are needed. Extractive distillation can also be used to effect the desired separation. This method also uses a two column system but the operation is simple. Ethylene glycol has been proposed in the literature as an extractive distillation solvent for the system ethanol/water.
As has been stated in US Patent 5,800,681 (Berg) extractive distillation is the method of separating close boiling compounds from each other by carrying out the distillation in a multiplate rectification column in the
presence of an added liquid or liquid mixture, said liquid(s) having a boiling point higher than the compounds being separated. The extractive distillation solvent is introduced near the top of the column and flows downward until it reaches the stillpot or reboiler. Its presence on each plate of the rectification column alters the relative volatility of the close boiling compounds in a direction to make the separation on each plate greater and thus require either fewer plates to effect the same separation or make possible a greater degree of separation with the same number of plates. The extractive distillation solvent should boil higher than any of the close boiling liquids being separated and not form minimum azeotropes with them. Usually the extractive distillation solvent is introduced a few plates from the top of the column to ensure that none of the extractive distillation solvent is carried over with the lowest boiling component.
It is an object of this invention to suggest at least one further extractive distillation solvent for the separation of ethanol and water from mixtures thereof.
SUMMARY OF INVENTION
According to the invention, a method of separation of ethanol and water includes the step of distilling a mixture of ethanol / water containing at least ethanol and water by way of an extractive distillation process in the presence of an extractive distillation solvent selected from the group consisting of an amine and a chlorinated hydrocarbon.
The ethanol / water mixture may contain only ethanol and water.
The amine may be diaminobutane.
The amine may be 1 ,3-diaminopentane.
The amine may be diethylene triamine.
The chlorinated hydrocarbon may be hexachlorobutadiene.
BRIEF DESCRIPTION OF DRAWING
The invention will now be described by way of example with reference to the accompanying schematic drawing.
In the drawing there is shown a schematic view of an experimental apparatus for testing an extractive distillation solvent for separating ethanol and water from mixtures thereof in accordance with the invention.
DETAILED DESCRIPTION OF DRAWING AND EXPERIMENT
In the drawing there is shown a vapour-liquid equilibrium still 10 including a bulb flask 12 having a tube 14 leading to a condenser 16 and terminating in an outlet 18. The outlet 18 has an electromagnetic closure mechanism 20.
A liquid phase sample conduit 22 leads into the flask 12.
A further liquid phase sample conduit 24 leads into the tube 14.
A first thermometer 26 is adapted to read the temperature of the liquid contained in the flask 12, and a second thermometer 28 is adapted to read the temperature of the vapour in the tube 14.
The flask 12 can be heated by a heating mantle 30.
The extractive distillation procedure is as follows:
A liquid mixture is prepared consisting of ethanol, water and an extractive distillation solvent. The liquid is introduced into the bulb flask 12 via conduit 22.
The mixture in the bulb flask 12 is then heated by the heating mantle 30 and kept at boiling point.
During boiling the mixture separates into a liquid phase remaining in the bulb flask 12 and a vapour phase in the tube 14. In the tube 14 the
vapour phase is cooled by the condenser 16, whereafter it condenses and returns as liquid to the bulb flask 12.
The mixture is boiled and condensed for several hours, normally 5 to 6 hours. The process of evaporation and condensation is repeated until equilibrium is reached between the vapour and liquid phases. Thereafter, a liquid sample of the liquid phase in the bulb flask 12 is extracted through conduit 22 and a liquid sample of the condensed vapour phase in the tube 14 is extracted through conduit 24.
The temperature of the liquid phase in the bulb flask 12 is continuously monitored by the thermometer 26, and the temperature of the vapour phase in the tube 14 is continuously monitored by the thermometer 28.
Experiment 1
An ethanol/water liquid mixture with a molar ratio of 1.25:1 has a relative volatility of 1.71.
The separation was effected by using a suitable amine as an extractive distillation solvent.
A mixture of ethanol (23.7g), water (7.4g) and diethylenetriamine (330.7g) was charged into the flask 12 of the vapour-liquid equilibrium still 10 and the above procedure was applied. The liquid and vapour phases were analysed. The liquid and vapour molar fractions were determined to be as follows:
Table 1 :
This translates to a relative volatility of 2.4 for the system ethanol/water in the ternary system shown above, the ethanol being the distillate.
Experiment 2
An ethanol/water liquid mixture with a molar ratio of 4:1 has a relative volatility of 1.12.
The separation was effected by using a suitable amine as an extractive distillation solvent.
A mixture of ethanol (11.1g), water (1.1g) and 1 ,3-diaminopentane (197.7g) was charged into the flask 12 of the vapour-liquid equilibrium still 10 and the above procedure was applied. The liquid and vapour phases were analysed. The liquid and vapour molar fractions were determined to be as follows: Table 2:
This translates to a relative volatility of 1.33 for the system water/ethanol in the ternary system shown above, the water being the distillate.
Experiment 3
An ethanol/water mixture with a molar ratio of 0.9:1 has a relative volatility of 2.07.
The separation was effected by using a suitable chlorinated hydrocarbon as an extractive distillation solvent.
A mixture of ethanol (16.34g), water (7.1g) and hexachlorobutadiene (372.2g) was charged into the flask 12 of the vapour-liquid equilibrium still 10 and the above procedure was applied. The liquid and vapour phases were analysed. The liquid and vapour molar fractions were determined to be as follows:
Table 3:
This translates to a relative volatility of 2.43 for the system ethanol/water in the ternary system shown above, the ethanol being the distillate.
Claims
1. A method of separation of ethanol and water, which includes the step of distilling a mixture of ethanol / water containing at least ethanol and water by way of an extractive distillation process in the presence of an extractive distillation solvent selected from the group consisting of an amine and a chlorinated hydrocarbon.
2. A method as claimed in claim 1 , in which the ethanol / water mixture contains only ethanol and water.
3. A method as claimed in claim 1 or claim 2, in which the amine is diaminobutane.
4. A method as claimed in claim 1 or claim 2, in which the amine is 1 ,3-diaminopentane.
5. A method as claimed in claim 1 or claim 2, in which the amine is diethylene triamine.
6. A method as claimed in claim 1 or claim 2, in which the chlorinated hydrocarbon is hexachlorobutadiene.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU30699/00A AU3069900A (en) | 1999-01-28 | 2000-01-26 | Separation of ethanol and water from mixtures thereof by extractive distillation |
| US09/671,335 US6375807B1 (en) | 1999-01-28 | 2000-09-28 | Separation of ethanol mixtures by extractive distillation |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA99/0660 | 1999-01-28 | ||
| ZA99661 | 1999-01-28 | ||
| ZA99/0661 | 1999-01-28 | ||
| ZA99660 | 1999-01-28 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2000/000074 Continuation WO2000044696A1 (en) | 1999-01-28 | 2000-01-26 | Separation of ethanol and ethyl acetate from mixtures thereof by extractive distillation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2000044697A1 true WO2000044697A1 (en) | 2000-08-03 |
Family
ID=27145156
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2000/000076 WO2000044697A1 (en) | 1999-01-28 | 2000-01-26 | Separation of ethanol and water from mixtures thereof by extractive distillation |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU3069900A (en) |
| WO (1) | WO2000044697A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7132051B2 (en) | 2002-03-12 | 2006-11-07 | Solvay Solexis, S.P.A. | Liquid-liquid extraction of polar organic substances from their aqueous solutions with fluorinated extracting liquids |
| CN102627556A (en) * | 2012-03-23 | 2012-08-08 | 河北工业大学 | Technology of extractive distillation separation of ethyl acetate-ethanol-water |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0047204A2 (en) * | 1980-09-01 | 1982-03-10 | Institut Français du Pétrole | Process for the production of dehydrated alcohols for use as components in a motor fuel |
| US4559109A (en) * | 1983-03-31 | 1985-12-17 | Phillips Petroleum Company | Dehydration of alcohol with extractive distillation |
-
2000
- 2000-01-26 WO PCT/IB2000/000076 patent/WO2000044697A1/en active Application Filing
- 2000-01-26 AU AU30699/00A patent/AU3069900A/en not_active Abandoned
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0047204A2 (en) * | 1980-09-01 | 1982-03-10 | Institut Français du Pétrole | Process for the production of dehydrated alcohols for use as components in a motor fuel |
| US4559109A (en) * | 1983-03-31 | 1985-12-17 | Phillips Petroleum Company | Dehydration of alcohol with extractive distillation |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7132051B2 (en) | 2002-03-12 | 2006-11-07 | Solvay Solexis, S.P.A. | Liquid-liquid extraction of polar organic substances from their aqueous solutions with fluorinated extracting liquids |
| CN102627556A (en) * | 2012-03-23 | 2012-08-08 | 河北工业大学 | Technology of extractive distillation separation of ethyl acetate-ethanol-water |
| CN102627556B (en) * | 2012-03-23 | 2013-12-25 | 河北工业大学 | Technology of extractive distillation separation of ethyl acetate-ethanol-water |
Also Published As
| Publication number | Publication date |
|---|---|
| AU3069900A (en) | 2000-08-18 |
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