Process for producing butadiene from ethanol integrated with extractive distillation

Patent metadata

Field	Value
Publication number	US-10654763-B2
Application number	US-201716314194-A
Country	US
Kind code	B2
Filing date	Jun 26, 2017
Priority date	Jun 29, 2016
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

The invention relates to a process for producing butadiene from an ethanol feedstock comprising a step of converting ethanol into butadiene, a step of separating the reactants into a hydrated butadiene effluent, an impurities effluent and an ethanol-butadiene effluent, a separation step that separates the ethanol-butadiene effluent into a butadiene distillate and a contaminated reactants effluent, a step of purifying the butadiene by extractive distillation and an effluent treatment step.

First claim

The invention claimed is:

1. A process for producing butadiene from an ethanol feedstock comprising at least 80% by weight of ethanol, said process comprising:
A) converting ethanol in a fraction of the ethanol feedstock into butadiene in at least one reaction section at a pressure between 0.1 and 1.0 MPa and at a temperature between 200° C. and 500° C. in the presence of a catalyst, and producing at least one reaction effluent comprising ethanol, butadiene and impurities, wherein the at least one reaction section is also fed with at least a fraction of an ethanol effluent and/or an ethanol- acetaldehyde effluent that results from step E) of this process;
B) separating the reaction effluent into at least an ethanol-butadiene effluent, an impurities effluent, and a hydrated butadiene effluent;
C) separating said ethanol-butadiene effluent into at least a butadiene distillate and a contaminated reactants residue comprising ethanol and acetalehyde;
D) purifying butadiene in the hydrated butadiene effluent and in the butadiene distillate by the steps comprising:
i) feeding said hydrated butadiene effluent resulting from step B), as a mixture with said butadiene distillate resulting from step C) and with a stream comprising a solvent to a section for separating the butene with extractive distillation to obtain an overhead light gas effluent comprising butene, and a bottoms comprising a butadiene residue, and distilling said butadiene residue into an overhead butadiene distillate and a bottoms comprising a solvent residue;
ii) separating oxygenated compounds from the overhead butadiene distillate by extractive distillation with a stream comprising solvent to produce an overhead comprising prepurified butadiene effluent, and a bottoms comprising spent solvent residue, and distilling said spent solvent residue to separate an overhead oxygenated compounds effluent and a bottoms comprising solvent residue; and
iii) distilling said prepurified butadiene effluent resulting from the separating the oxygenated compounds in D) ii) in a final distillation section to produce an overhead comprising a purified butadiene effluent and a bottoms comprising a 2-butene residue; and

E) treating in an effluent treatment step at least the contaminated reactants residue resulting from step C) and the oxygenated compounds effluent resulting from step D) ii), to produce at least the ethanol effluent, the ethanol-acetaldehyde effluent, and one or more brown oil effluents.

2. The process according to claim 1 , in which said reaction section of said step A) comprises two reaction zones, the first fed with a fraction of said ethanol effluent and a portion of said ethanol feedstock, and the second fed with the effluent from the first reaction zone, with the residual fraction of said ethanol effluent and with a fraction of the ethanol-acetaldehyde effluent resulting from step E) and optionally with a portion of said ethanol feedstock, the ethanol/acetaldehyde molar ration of the inlet of said second reaction zone being between 1 and 5 .

3. The process according to claim 2 , in which gas-liquid separation is conducted between the two reaction zones in order to separate the effluent from the first reaction section into a gas effluent and a liquid effluent, the liquid effluent feeding the second reaction zone.

4. The process according to claim 1 , in which said step B) comprises:
separating said reaction effluent in a gas-liquid separation section into a liquid effluent comprising said ethanol-butadiene effluent and a gas effluent,
compressing said gas effluent to give a compressed gas effluent compressed to a pressure between 0.1 and 1.0 MPA, and
separation said compressed gas effluent in a distillation section into an overhead, said hydrated butadiene effluent and a bottoms comprising said impurities effluent.

5. The process according to claim 4 , in which said gas-liquid separation section of said step B) is operated at a temperature between 10° C. and 20° C.

6. The process according to claim 4 , in which said gas-liquid separation section of said B) is operated at a temperature between 40° C. and 50° C.

7. The process according to claim 4 , in which said impurities effluent resulting from step B) is sent to the effluent treatment step E) as a mixture with the contaminated reactants residue resulting from step C).

8. The process according to claim 1 , in which said step B) comprises:
a first gas-liquid separation section that separates said reaction effluent into a liquid effluent comprising said impurities effluent and a gas effluent, operated at a temperature between 70° C. and 80° C., and a pressure of between 0.1 and 0.3 MPa,
a compression section that compresses said gas effluent to give a gas effluent compressed to a pressure between 0.1 and 1.0 MPa, and
a second gas-liquid separation section fed with said compressed gas effluent and that separates, as gas phase, said hydrated butadiene effluent and, as a liquid phase, said ethanol-butadiene effluent, operated at a temperature of between 40° C. and 50° C. and a pressure of between 0.2 and 0.6 MPa.

9. The process according to claim 8 , in which said hydrated butadiene effluent resulting from said second gas-liquid separation section is fed to a distillation section that separates from said hydrated butadiene effluent, as bottoms, an oxygenated compounds residue and, as overhead, a hydrated butadiene effluent depleted in oxygenated compounds, said hydrated butadiene effluent depleted in oxygenated compounds then feeding step D) as hydrated butadiene effluent.

10. The process according to claim 9 , in which said oxygenated compounds residue feeds said effluent treatment step E) as a mixture with said contaminated reactants residue resulting from step C).

11. The process according to claim 9 , in which said hydrated butadiene effluent obtained from said distillation section is fed to a water-washing section comprising at least one gas-liquid washing section fed at the bottom with said hydrated butadiene effluent and at the top with a stream of water, and producing, as overhead, a hydrated butadiene effluent, depleted in oxygenated compounds, that feeds step D) and, as bottoms, a spent water raffinate.

12. The process according to claim 8 , in which said hydrated butadiene effluent obtained from said second gas-liquid separation section feeds a water-washing section comprising at least one gas-liquid washing section fed at the bottom with said hydrated butadiene effluent and at the top with a stream of water, and producing, as overhead, a hydrated butadiene effluent, depleted in oxygenated compounds, that feeds step D) and, as bottoms, a spent water raffinate.

13. The process according to claim 1 , in which said solvent of said butene separation section is selected from the group consisting of dimethylformamide (DMF), N-methylpyrrolidone and acetonitrile.

14. The process according to claim 1 , in which the solvent residue resulting from the butene separation in D) i) and the solvent residue resulting from separation the oxygenated compounds in D) ii) are mixed and purified to obtain purified solvent.

15. The process according to claim 1 , in which said step E) comprises at least a washing/backwashing section, a section for distilling light brown oils, a section for distilling heavy brown oils, an acetaldehyde separation section and an ethanol-water separation section.

Assignees

• Ifp Energies Now
• Michelin & Cie

Inventors

• Dastillung Rejane
• Couderc Sophie
• Thinon Olivier

Classifications

• C07C7/08

  by extractive distillation · CPC title

• C07C1/20 Primary

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

• C07C11/167

  1, 3-Butadiene · CPC title

• C07C7/005

  Processes comprising at least two steps in series · CPC title

• C07C7/04

  by distillation · CPC title