US-12618086-B2 - Method for producing alcohols using a support on which microorganisms are immobilised

US12618086B2US 12618086 B2US12618086 B2US 12618086B2US-12618086-B2

Abstract

The present invention relates to a process for producing alcohols, according to which a sugary fluid ( 2 ) is introduced into a reaction section ( 1 ) comprising a support ( 4 ) on which microorganisms are immobilized, in order to produce, by fermentation, an alcohol-enriched must ( 3 ) under the action of said microorganisms, characterized in that the process is carried out continuously, and such that a portion of spent support ( 41 ) is periodically replaced by a portion of new and/or regenerated support ( 46 ).

Inventors

Jean-Christophe GABELLE
Eszter Toth
Nicolas Lopes Ferreira
HELENE VELLY
AMANDINE GINET
SEVERINE ARTERO

Assignees

IFP Energies Nouvelles

Dates

Publication Date: 20260505
Application Date: 20211202
Priority Date: 20201218

Claims (20)

1 . A process for producing alcohols, characterized in that it is a process for producing a mixture of alcohols of Acetone-Butanol-Ethanol type, Isopropanol-Butanol-Ethanol type, or Isopropanol-Butanol-Ethanol-Acetone type, according to which a sugary fluid ( 2 ) is introduced into a reaction section ( 1 ) comprising a support made of porous solid material and comprising a plurality of portions or layers of loose porous solid material, which are arranged successively in a general direction of flow of said sugary fluid ( 2 ) in the reaction section ( 1 ), ( 4 ) on which microorganisms of the genus Clostridium , which microorganisms produce isopropanol naturally, are genetically modified to produce isopropanol, or both, are immobilized, in order to produce, by fermentation, an alcohol-enriched must ( 3 ) under the action of said microorganisms, characterized in that the process is carried out continuously, in that a portion of spent support ( 41 ) is periodically replaced by a portion of new support, by a portion of regenerated support, or by a portion of a combination of new support and regenerated support ( 46 ), characterized in that only a portion is replaced each time a replacement is made.
2 . The process as claimed in claim 1 , characterized in that the microorganisms are immobilized in the form of biofilms or aggregates on the support ( 4 ).
3 . The process as claimed in claim 1 , characterized in that said plurality of support portions have a decreasing degree of deterioration from upstream to downstream.
4 . The process as claimed in claim 1 , characterized in that the portion of spent support ( 41 ) which is furthest upstream in the support ( 4 ) is replaced by the portion of new support, by the portion of regenerated support, or by the portion of the combination of new support and regenerated support ( 46 ) which is placed downstream of the furthest downstream portion of the support.
5 . The process as claimed in claim 1 , characterized in that the support ( 4 ) comprises loose blocks of porous solid material immersed in a liquid reaction medium bathing the reaction section, and which are held in the reaction section by mechanical devices, which are meshed or are in the form of deflectors ( 8 ).
6 . The process as claimed in claim 1 , characterized in that the reaction section comprises a reactor ( 1 ), and in that the support comprises a plurality of layers ( 41 , 42 , 43 , 44 , 45 ), successively passed through by the sugary fluid ( 2 ), the portion of spent support ( 41 ) and the portion of new support, the portion of regenerated support, or the portion of a combination of new support and regenerated support ( 46 ) each corresponding to a layer of the support, the portion of spent support withdrawn from the reactor being the furthest upstream layer of the support and the portion of new support, the portion of regenerated support, or the portion of a combination of new support and regenerated support being introduced into the reactor downstream of the furthest downstream layer of the support.
7 . The process as claimed in claim 1 , characterized in that the portion or layer of new support, by a portion of regenerated support, or by a portion of a combination of new support and regenerated support ( 46 ) is introduced in the form of loose blocks of material, into the reactor, in solid form or in a liquid phase.
8 . The process as claimed in claim 6 , characterized in that the spent portion or layer of the support ( 41 ) is withdrawn from the reactor in the liquid phase, notably in suspension in the liquid phase of the fermentation must leaving the reactor.
9 . The process as claimed in claim 6 , characterized in that the withdrawal of the portion or layer of spent substrate ( 41 ) at one of its ends, and the replacement thereof by a portion or layer of new support, by a portion of regenerated support, or by a portion of a combination of new support and regenerated support ( 46 ) at its opposite end is carried out counter current relative to the direction of flow of the sugary fluid ( 2 ) in the reaction section.
10 . The process as claimed in claim 6 , characterized in that the reactor ( 1 ) is oriented essentially vertically, with: either a flow of the sugary fluid ( 2 ) in the reactor from top to bottom, and the support ( 4 ) extending over at least one part of the height of the working volume of the reactor, the portion of spent support ( 41 ) being withdrawn from the reactor in the highest part of the support, and the portion of new support, by the portion of regenerated support, or by the portion of the combination of new support and regenerated support ( 46 ) being introduced into the reactor in the lowest part of the support, or a flow of the sugary fluid ( 2 ) in the reactor from bottom to top, and the support extending over at least one part of the height of the working volume of the reactor, the portion of spent support ( 41 ) being withdrawn from the reactor in the lowest part of the support, and the portion of new support, by the portion of regenerated support, or by the portion of the combination of new support and regenerated support ( 46 ) being introduced into the reactor in the highest part of the support.
11 . The process as claimed in claim 1 , characterized in that the reaction section comprises a series of n reactors ( 31 , 32 , 33 ) fluidically connected in series to one another, and at least one spare reactor ( 34 ), the support ( 4 ) being distributed between the n reactors in the form of n support portions, and in that a portion of the spent support is periodically replaced by a portion of new or regenerated support by disconnecting a reactor ( 31 ) belonging to the series of n reactors in series and containing the portion of spent support and by connecting the spare reactor ( 34 ) containing a portion of new or regenerated support to the series of n−1 reactors.
12 . The process as claimed in claim 11 , characterized in that the reactor ( 31 ) which is disconnected is the furthest upstream reactor with respect to the general direction of flow of the sugary fluid ( 2 ) through the series of n reactors, and in that the spare reactor ( 34 ) which is connected is placed downstream of the furthest downstream reactor ( 33 ) of the series with respect to said direction of flow.
13 . The process as claimed in claim 11 , characterized in that once the reactor ( 31 ) containing the portion of spent support has been disconnected, the reactor is drained and at least one operation is performed for treating the spent support, at least one of the at least one operation comprising regenerating the spent support or replacing the spent support with a new support.
14 . The process as claimed in claim 1 , characterized in that the reaction section comprises at least one reactor ( 1 ) which is provided with a fluid recirculation loop ( 7 ).
15 . The process as claimed in claim 1 , characterized in that the periodic replacement of the portion of spent support ( 41 ) by the portion of new support, by the portion of regenerated support, or by the portion of the combination of new support and regenerated support ( 46 ) is carried out with constant or increasing time intervals, or intervals that decrease with time, or according to time intervals controlled according to a measurement or an evaluation of the degree of deterioration of the support.
16 . The process as claimed in claim 1 , characterized in that a fermentation must is produced comprising isopropanol, butanol and ethanol.
17 . The process as claimed in claim 5 , characterized in that the meshed mechanical devices are selected from screens and nets.
18 . The process as claimed in claim 5 , characterized in that the loose blocks of porous solid material are based on polymer foam or ceramic material foam.
19 . The process as claimed in claim 7 , characterized in that the portion or layer of new support, by a portion of regenerated support, or by a portion of a combination of new support and regenerated support ( 46 ) is introduced in the form of loose blocks of material, into the reactor, in solid form via endless screw, or in a liquid phase-in suspension in the sugary fluid supplying the reaction section.
20 . The process as claimed in claim 13 , characterized in that the reactor ( 31 ) is sterilized and is stored as a spare reactor.

Description

TECHNICAL FIELD The present invention relates to a process for producing alcohols by fermentation of a sugary fluid. 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 processes (for example isopropanol and n-butanol) are among the most promising replacements for petrochemical derivatives. ABE (Acetone—Butanol—Ethanol) fermentation, performed by microorganisms belonging to the genus Clostridium, is one of the oldest fermentations to have been industrialized, and has since been extensively studied. More recently, IBE (Isopropanol—Butanol—Ethanol) fermentation, producing a mixture of isopropanol, butanol and ethanol and also performed by microorganisms belonging to the genus Clostridium, has been the subject of numerous studies. As regards the fermentation approach employed in this type of process, batch production remains the conventional method for ABE and IBE fermentations, despite the low productivity displayed for this type of process, in the range 0.1-0.7 g/L·h (see, for example, Jones D. T., Woods D. R., 1986, Acetone-Butanol Fermentation Revisited. Microbiol. Rew., 50 (4), 484-524 or Table 16.6 Lopez-Contreras A. et al. chapter book 16, Bioalcohol Production: Biochemical Conversion of Lignocellulosic Biomass, 2010). However, these productivities remain too low to envisage an economically viable industrial process. A continuous process with cells in suspension in a homogeneous reactor may also be envisaged. However, the productivity is also relatively low and cannot easily be significantly increased. One technical problem is the concentration of the cells in the fermentation medium, which is mainly controlled by the dilution rate applied in the process. This rate cannot be high, to avoid cell “wash-out” in the fermenter. For these reasons, great interest has been shown in recent years in methods directed toward high retention of the microbial biomass. Two means exist: “immobilization of the cells” and cell “recycling” with retention by means of membrane filters. The present invention will mainly focus on the cell immobilization technique. Two immobilization techniques for the continuous process are known: adsorption on a solid support and entrapment, the two techniques having been studied in the literature for ABE production. In the first case of adsorption on a solid support, the physical adsorption of microorganisms onto a solid surface takes place via electrostatic forces, van der Waals forces, or by covalent bonding between the bacterial cell membrane and the support. As there is no physical barrier between the microbial biofilm and the fermentation solution, various equilibria between the degrees of adsorption, of cell detachment and of recolonization of the solid support may be achieved as a function of the solid support, of the implementation and of the operating conditions. It should be noted that the immobilized cells are typically surrounded by polysaccharides excreted by the microorganisms (EPS: “Extracellular Polymeric Substances”), and have different growth and bioactivity regimes from those obtained when the cells are in suspension (see, for example, Halan B., Buehler K., Schmid A., 2012, Biofilms as living catalysts in continuous chemical syntheses, Trends in Biotechnol., 30 (9), 453-465). Several solid supports have been tested and prove to be advantageous according to the literature for ABE fermentation, including charcoal (see, for example, Qureshi N., Maddox I. S., 1987, Continuous solvent production from whey permeate using cells of Clostridium acetobutylicum immobilized by adsorption onto bonechar, Enzyme Microb. Technol., (9), 668-371), bricks (see, for example, Qureshi N., Schripsema J., Lienhardt J., Blaschek H. P., 2000, Continuous solvent production by Clostridium beijerinckii BA101 immobilized by adsorption onto brick, World Journal of Microbiology & Biotechnology, (16), 377-382), and paper pulp (see, for example, Survase S. A., van Heiningen A., Granström T., 2012, Continuous bio-catalytic conversion of sugar mixture to acetone-butanol-ethanol by immobilized Clostridium acetobutylicum DSM 792, Appl. Microbiol. Biotechnol., (93), 2309-2316). But such solid supports are not synthetic and may give rise to major problems of reproducibility for fermentation processes. In the second case, that of immobilization by entrapment, of encapsulation type, the microorganisms are introduced inside a porous matrix, so as to prevent their diffusion into the external medium, while at the same time allowing the transfer of material for the support and the nutrients, and also for the reaction products. Examples of supports using the encapsulation entrapment technique include alginate beads (see, for example, Mollah A. H., Stuckey D. C., 1993, Maximizing the production o