Optimized IBE fermentation method for upgrading acetone
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).
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 . The process as claimed in claim 1 , wherein the reaction section of step a) is additionally fed with an exogenous acetone stream.
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 . 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 . 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 . The process as claimed in claim 1 , wherein the reaction section of step a) is operated at atmospheric pressure.
7 . The process as claimed in claim 1 , wherein the reaction section includes at least two bioreactors, and at most thirty bioreactors.
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 . The process as claimed in claim 1 , wherein the fermentation is carried out in semi-continuous mode for 20 to 200 hours.
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 . 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 . 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 . 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 . 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 . 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 . 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 . The process as claimed in claim 16 , wherein the reaction section of step a) is additionally fed with an exogenous acetone stream.