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US-12618085-B2 - Optimized IBE fermentation method for upgrading acetone

US12618085B2US 12618085 B2US12618085 B2US 12618085B2US-12618085-B2

Abstract

The present invention relates to a process for producing alcohols comprising: a. an IBE-type fermentation step in at least one bioreactor (R 1 ) in the presence of a natural strain microorganism, and fed at least with an aqueous solution ( 1 ) of C5 and/or C6 sugars and a recycled acetone stream ( 3 ), in order to produce fermentation gases and a fermentation broth containing fermentation products; b. a step of recovering the fermentation products, in order to obtain a stream of fermentation products ( 2 ); c. a step of treating the stream of fermentation products comprising an acetone separation section in order to produce at least an acetone effluent ( 3 ) and an aqueous alcohol effluent ( 4 ); d. a step for recycling at least a fraction of the acetone effluent ( 3 ) from step c) to step a).

Inventors

  • Marcel Ropars
  • Nicolas Lopes Ferreira
  • Sandra Menir
  • Helena GONZALEZ PENAS
  • Eszter Toth
  • Vincent Coupard

Assignees

  • IFP Energies Nouvelles

Dates

Publication Date
20260505
Application Date
20210617
Priority Date
20200629

Claims (17)

  1. 1 . A process for producing alcohols comprising the following steps: a. a fermentation step using a reaction section comprising at least one bioreactor wherein an Isopropanol-Butanol-Ethanol-type fermentation is carried out in the presence of a strain of Clostridium that naturally synthesizes, during fermentation, at least one secondary alcohol dehydrogenase (sadh) enzyme that enables the conversion of acetone to isopropanol in the presence of nicotinamide adenine dinucleotide phosphate (NADPH), said reaction section being fed at least with an aqueous solution of C5 or C6 sugars or a combination thereof and a recycled acetone stream, in order to produce fermentation gases and a fermentation broth containing fermentation products comprising butanol, ethanol, isopropanol and acetone; b. a step of recovering the fermentation products, in order to obtain a stream of fermentation products; c. a step of treating the stream of fermentation products from step b) using an acetone separation section in order to produce at least an acetone effluent having an acetone concentration of greater than or equal to 95% by weight, relative to the weight of said acetone effluent, and an aqueous alcohol effluent; d. a step of recycling the acetone which uses at least one transfer section in order to recycle at least one fraction of the acetone effluent from step c) to step a), said at least one fraction of the acetone effluent which is transferred constituting said recycled acetone stream which feeds the reaction section of step a).
  2. 2 . The process as claimed in claim 1 , wherein the reaction section of step a) is additionally fed with an exogenous acetone stream.
  3. 3 . The process as claimed in claim 2 , wherein the reaction section of step a) is fed with said recycled acetone stream and said exogenous acetone stream, at flow rates that are adjusted so that the concentration of acetone in all of the liquid streams, composed of the aqueous solution of C5 or C6 sugars or a combination thereof, the recycled acetone stream and the exogenous acetone stream, feeding the reaction section of step a) is less than or equal to 10 g/l.
  4. 4 . The process as claimed in claim 1 , wherein the fermentation carried out in the reaction section of step a) is carried out at a temperature of between 25° C. and 40° C.
  5. 5 . The process as claimed in claim 1 , wherein the fermentation carried out in the reaction section of step a) is carried out at a pH of between 4 and 7.
  6. 6 . The process as claimed in claim 1 , wherein the reaction section of step a) is operated at atmospheric pressure.
  7. 7 . The process as claimed in claim 1 , wherein the reaction section includes at least two bioreactors, and at most thirty bioreactors.
  8. 8 . The process as claimed in claim 1 , wherein the fermentation is carried out in batch mode for a period of between 30 and 150 hours.
  9. 9 . The process as claimed in claim 1 , wherein the fermentation is carried out in semi-continuous mode for 20 to 200 hours.
  10. 10 . The process as claimed in claim 1 , wherein the fermentation is carried out in simple continuous mode, the concentration of Clostridium strain in the reaction medium is between 10 8 and 10 11 cells/ml of reaction medium.
  11. 11 . The process as claimed in claim 1 , wherein the fermentation is carried out in supported continuous mode, the Clostridium strain being in the form of a biofilm on a solid support and the concentration of Clostridium strain in the reaction medium is between 10 7 and 10 10 cells/cm 3 of solid support.
  12. 12 . The process as claimed in claim 1 , wherein step c) carries out, in said acetone separation section: c-1) a distillation of the stream of fermentation products from step b) in a beer column in order to obtain a stream of water at the bottom of said beer column and an aqueous mixture of solvents at the top of the beer column, c-2) a distillation of the aqueous mixture of solvents in a distillation column, in order to obtain said acetone effluent at the top of the column and said aqueous alcohol effluent at the bottom of the column.
  13. 13 . The process as claimed in claim 1 , wherein the reaction section of step a) is fed with said recycled acetone stream at a flow rate that is adjusted so that the concentration of acetone in all of the liquid streams, composed of the aqueous solution of C5 or C6 sugars or a combination thereof, and the recycled acetone stream, feeding the reaction section of step a) is less than or equal to 10 g/l.
  14. 14 . The process as claimed in claim 1 , wherein the strain of Clostridium is a C. beijerinckii bacterium, a C. diolis bacterium, a C. puniceum bacterium, a C. aurantibutyricum bacterium, a C. butyricum bacterium, a C. saccharoperbutylacetonicum bacterium, a C. botulinum bacterium, a C. drakei bacterium, a C. scatologenes bacterium, a C. perfringens bacterium or a C. tunisiense bacterium.
  15. 15 . The process as claimed in claim 1 , wherein the strain of Clostridium is a C. beijerinckii bacterium DSM 6423, LMG 7814, LMG 7815, NRRL B-593 or NCCB 27006, or a C. aurantibutyricum DSZM 793 or ATCC 17777 bacterium.
  16. 16 . A process for producing alcohols comprising the following steps: a. a fermentation step using a reaction section comprising at least one bioreactor wherein an Isopropanol-Butanol-Ethanol-type fermentation is carried out in the presence of Clostridium beijerinckii DSM6423, said reaction section being fed at least with an aqueous solution of C5 or C6 sugars or a combination thereof and a recycled acetone stream, in order to produce fermentation gases and a fermentation broth containing fermentation products comprising butanol, ethanol, isopropanol and acetone; b. a step of recovering the fermentation products, in order to obtain a stream of fermentation products; c. a step of treating the stream of fermentation products from step b) using an acetone separation section in order to produce at least an acetone effluent having an acetone concentration of greater than or equal to 95% by weight, relative to the weight of said acetone effluent, and an aqueous alcohol effluent; d. a step of recycling the acetone which uses at least one transfer section in order to recycle at least one faction of the acetone effluent from step c) to step a), said at least one fraction of the acetone effluent which is transferred constituting said recycled acetone stream which feeds the reaction section of step a).
  17. 17 . The process as claimed in claim 16 , wherein the reaction section of step a) is additionally fed with an exogenous acetone stream.

Description

TECHNICAL FIELD The present invention relates to a process for producing alcohols comprising the IBE fermentation of an aqueous solution comprising C5 and/or C6 sugars in the presence of natural microorganisms, making it possible to maximize the yield of alcohols, in particular of isopropanol. PRIOR ART In order to meet the energy transition challenges, considerable research is being conducted to develop “green” processes, affording access to chemical intermediates in an alternative manner to petroleum refining and/or petrochemistry. Alcohols derived from fermentation (ethanol, n-butanol, denoted butanol hereinafter, isopropanol) are the most promising replacements for petrochemical derivatives. ABE (Acetone—Butanol—Ethanol) fermentation is one of the oldest fermentations to have been industrialized (at the start of the 20th century) and has since been extensively studied (cf. Moon et al. “One hundred years of clostridial butanol fermentation.” FEMS Microbiol Lett. 2016 February, 363, 3). There is also IBE (Isopropanol—Butanol—Ethanol) fermentation which produces a mixture of isopropanol, butanol and ethanol (cf. Dos Santos Vieira et al. “Acetone-free biobutanol production: Past and recent advances in the Isopropanol-Butanol-Ethanol (IBE) fermentation.” Bioresour Technol. 2019 September, 287:121425). These two types of fermentations are carried out under strict anaerobiosis by a fermentation microorganism generally of the genus Clostridium. These “solventogenic” non-pathogenic strains of Clostridia, used in biotechnology, naturally have the ability to convert a large variety of sugars in order to produce chemical species of interest, and more particularly a mixture of acetone, butanol and ethanol during ABE fermentation (Jones et al. “Acetone-butanol fermentation revisited.” Microbiol Rev 1986, 50: 484-524). Some are themselves capable of producing a mixture of isopropanol, butanol and ethanol during an IBE fermentation (Chen et al., “Acetone-butanol-isopropanol production by Clostridium beijerinckii (synonym, Clostridium butylicum).” Biotechnol Lett 1986, 8: 371-376; George et al., “Acetone, Isopropanol and Butanol Production by Clostridium beijerinckii (syn. Clostridium butylicum) and Clostridium aurantibutyricum.” Appl Environ Microbiol 1983, 45: 1160-1163). Only a few particular solvantogenic strains of Clostridia are naturally capable of producing isopropanol during the fermentation process as an almost total replacement for acetone, in particular certain strains of Clostridium beijerinckii (or C. beijerinckii), such as strain DSM6423. The other strains produce an Acetone/Butanol/Ethanol (A/B/E) mixture. During the IBE fermentation process which leads to the Isopropanol/Butanol/Ethanol (I/B/E) alcohol mixture, acetone is therefore an intermediate product of the fermentation production pathway of isopropanol (Máté de Gérando et al., “Genome and transcriptome of the natural isopropanol producer Clostridium beijerinckii DSM6423” BMC Genomics, 2018 19:242; Collas, 2012, “Production of isopropanol, butanol and ethanol by metabolic engineered Clostridia”, Doctoral thesis in Microbiology and Molecular Biology, AgroParisTech, France). However, at the end of IBE fermentation, carried out by the DSM6423 strain for example, the fermentation broth obtained systematically comprises acetone, often at a low concentration (generally around 2% of the mass of the solvents produced). This presence of acetone in the products of an IBE fermentation process is however characteristic of a yield of alcohols, in particular of isopropanol, which may be incomplete. It then appears useful, in order to make the large-scale fermentation production of I/B/E alcohols economically advantageous, to optimize conventional IBE fermentation processes by converting the co-produced acetone to alcohol, in particular to isopropanol, thus making it possible to limit the accumulation of this acetone by-product in the processes. Recovering and converting the acetone also makes it possible to upgrade it and especially to improve the sugar to alcohol conversion yields. Industrial processes for converting acetone to isopropanol by chemical means exist. These are conventional catalytic hydrogenation processes under pressure. For example, the processes described in documents EP 0379323 and US 2011/0218367 are processes for producing isopropanol by reaction of acetone with hydrogen in the presence of catalysts based on hydrogenating metal, in particular based on Raney nickel, at a temperature between 20° C. and 200° C. and a pressure between 1 and 80 bar (cf. EP 0379323). Application US 2011/0218367 specifies that the isopropanol selectivity is improved in the presence of water. U.S. Pat. No. 6,930,213 itself describes a process for the hydrogenation of acetone to isopropanol in several reaction stages so as to produce high-purity isopropanol with an improved selectivity. At the same time, the enzymatic pathway for converting acetone is explored. The l