Method for selectively separating impurities present in a hydro-alcoholic cut by recycling through a liquid-liquid extraction column

Patent metadata

Field	Value
Publication number	US-11141677-B2
Application number	US-201916971498-A
Country	US
Kind code	B2
Filing date	Jan 25, 2019
Priority date	Feb 22, 2018
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

Liquid-liquid extraction and distillation of a liquid feedstock of at least ethanol, water, acetaldehyde and at least one hydrocarbon-based impurity with a boiling point of between 20° C. and 100° C. at atmospheric pressure, or which generates, with at least one of the compounds of the liquid feedstock and/or with the organic extraction solvent and/or with the aqueous back-washing solvent, an azeotrope and a partition coefficient of between 0.1 and 5 at any point in a back-washing (BW) column of the extraction section, by (a) a liquid-liquid extraction step a washing (W) column, a back-washing (BW) column and at least one injection (F2) of a cut withdrawn in step b), located in the top half of the back-washing column, (b) distillation of an aldehyde and ethanol separation producing at least one aldehyde-rich effluent, one ethanol-rich effluent and one water-rich effluent.

First claim

The invention claimed is:

1. A process for the treatment by liquid-liquid extraction and distillation of a liquid feedstock comprising at least ethanol, water and acetaldehyde and at least one hydrocarbon-based impurity with a boiling point of between 20° C. and 100° C. at atmospheric pressure, or generating, with at least one of the compounds of the liquid feedstock and/or with the organic extraction solvent and/or with the aqueous back-washing solvent, an azeotrope whose boiling point is between 20 and 100° C. at atmospheric pressure, and a partition coefficient of between 0.1 and 5 at any point in the back-washing (BW) column of the extraction section, comprising:
a) a liquid-liquid extraction step comprising an extraction section comprising a washing (W) column and a back-washing (BW) column, said extraction section being fed with said liquid feedstock at an intermediate point located between the top of the washing (W) column and the bottom of the back-washing (BW) column,
said washing (W) column being fed at the top with the stream originating from the bottom of the back-washing (BW) column and at the bottom with a stream of an organic extraction solvent,
said back-washing (BW) column being fed at the top with a stream of an aqueous back-washing solvent and at the bottom with the stream originating from the top of the washing (W) column,
said extraction section comprising at least one injection (F 2 ) of the cut withdrawn in step b), said injection (F 2 ) being located in the top half of the back-washing (BW) column,
said extraction section producing, at the bottom of the washing (W) column, a raffinate comprising at least water, ethanol, acetaldehyde and a portion of said hydrocarbon-based impurity and, at the top of the back-washing (BW) column, an extraction effluent comprising at least a portion of said hydrocarbon-based impurity;

b) a distillation step comprising:
at least one acetaldehyde separation step comprising an acetaldehyde separation section, composed of at least one distillation column (D 1 ) fed with the raffinate originating from step a) in an intermediate zone of the column (D 1 ) and producing at the top an acetaldehyde-rich effluent and at the bottom a water/ethanol effluent; and
at least one ethanol separation step comprising an ethanol separation section, composed of at least one distillation column (D 2 ) fed with the water/ethanol effluent originating from the bottom of the column (D 1 ) in an intermediate zone of the column (D 2 ), and producing at the top an ethanol-rich effluent and at the bottom a water-rich effluent,
at least one side withdrawal on the column (D 1 ) or the column (D 2 ) of a cut comprising at least one of the compounds ethanol or acetaldehyde, at a mass fraction of at least 10% of the total mass of the withdrawn cut, and said hydrocarbon-based impurity, at a mass fraction of between 0.5% and 50% of the total mass of the withdrawn cut, the side withdrawal being located in an intermediate zone of the column (D 1 ) or (D 2 ).

2. The treatment process as claimed in claim 1 , in which the feedstock comprises less than 5% by weight of hydrocarbon-based impurity.

3. The treatment process as claimed in claim 1 , in which the hydrocarbon-based impurity has a partition coefficient of between 0.2 and 2 at any point in the back-washing (BW) column of the extraction section.

4. The treatment process as claimed in claim 1 , in which the injection (F 2 ) is located in the top part of the back-washing (BW) column such that the distance between the top of the back-washing (BW) column and the injection (F 2 ) is equal to a length of between 10% and 30% of the total length of the back-washing (BW) column.

5. The treatment process as claimed in claim 1 , in which the recycled stream (F 2 ) is injected into step a) at a mass flow rate of between 0.1% and 10% of the mass flow rate of the liquid feedstock feeding the extraction section.

6. The treatment process as claimed in claim 1 , in which the recycled stream (F 2 ) comprises the hydrocarbon-based impurity at a mass concentration of between 0.5% and 50%.

7. The treatment process as claimed in claim 1 , in which the mass flow rate of organic extraction solvent in step a) is between 25% and 200% of the mass flow rate of the liquid feedstock feeding the extraction section.

8. The treatment process as claimed in claim 1 , in which the mass flow rate of aqueous solvent in step a) is between 10% and 80% of the mass flow rate of the liquid feedstock feeding the extraction section.

9. The treatment process as claimed in claim 1 , in which the liquid-liquid extraction step is performed at a temperature of between 10° C. and 70° C., at a pressure of between 0.1 MPa and 0.5 MPa and with residence times of between 0.5 and 10 hours in the washing column and between 0.5 and 6 hours in the back-washing column.

Assignees

• Ifp Energies Now
• Michelin & Cie

Inventors

• Augier Frederic
• Leinekugel Le Cocq Damien
• Dastillung Rejane
• Balz Pierre

Classifications

• B01D3/14 Primary

  Fractional distillation {or use of a fractionation or rectification column} · CPC title

• C07C45/82

  by distillation · CPC title

• C07C29/86

  by liquid-liquid treatment · CPC title

• C07C29/80

  by distillation · CPC title

• C07C1/20

  starting from organic compounds containing only oxygen atoms as heteroatoms · CPC title