Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/02—Preparation of oxygen-containing organic compounds containing a hydroxy group
  • C12P7/04—Preparation of oxygen-containing organic compounds containing a hydroxy group acyclic
  • C12P7/16—Butanols
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/02—Preparation of oxygen-containing organic compounds containing a hydroxy group
  • C12P7/04—Preparation of oxygen-containing organic compounds containing a hydroxy group acyclic
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/02—Preparation of oxygen-containing organic compounds containing a hydroxy group
  • C12P7/04—Preparation of oxygen-containing organic compounds containing a hydroxy group acyclic
  • C12P7/06—Ethanol, i.e. non-beverage
  • C12P7/08—Ethanol, i.e. non-beverage produced as by-product or from waste or cellulosic material substrate
  • C12P7/10—Ethanol, i.e. non-beverage produced as by-product or from waste or cellulosic material substrate substrate containing cellulosic material
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/02—Preparation of oxygen-containing organic compounds containing a hydroxy group
  • C12P7/04—Preparation of oxygen-containing organic compounds containing a hydroxy group acyclic
  • C12P7/06—Ethanol, i.e. non-beverage
  • C12P7/14—Multiple stages of fermentation; Multiple types of microorganisms or re-use of microorganisms
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P2201/00—Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P2203/00—Fermentation products obtained from optionally pretreated or hydrolyzed cellulosic or lignocellulosic material as the carbon source
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E50/00—Technologies for the production of fuel of non-fossil origin
  • Y02E50/10—Biofuels, e.g. bio-diesel

Definitions

• the present invention is part of a process for producing so-called "second generation" alcohols from lignocellulosic biomass.
• Lignocellulosic biomass is one of the most abundant renewable resources on earth.
• the substrates considered are very varied, since they concern both woody substrates (hardwood and softwood), agricultural by-products (straw) or lignocellulosic waste-generating industries (agro-food industries, paper mills).
• Lignocellulosic biomass is composed of three main polymers: cellulose (35 to 50%), hemicellulose (20 to 30%) which is a polysaccharide essentially consisting of pentoses and hexoses and lignin (15 to 25%) which is a polymer of complex structure and high molecular weight, composed of aromatic alcohols connected by ether bonds.
• Cellulose and possibly hemicelluloses are targets for enzymatic hydrolysis but are not directly accessible to enzymes. This is the reason why these substrates must undergo a pretreatment preceding the enzymatic hydrolysis step.
• the purpose of the pretreatment is to modify the physical and physicochemical properties of the lignocellulosic material, with a view to improving the accessibility of the cellulose trapped within the lignin and hemicellulose matrix.
• the effectiveness of the pretreatment is measured both by the material balance at the end of the pretreatment (recovery rate of sugars in the form of monomers or soluble oligomers or insoluble polymers) and also by the susceptibility to enzymatic hydrolysis of cellulosic and hemicellulosic residues.
• the pretreatment by steam explosion is distinguished by its performance in terms of degradability of cellulose and its low dilution ratio.
• Pretreatment by steam explosion is also known as “steam explosion”, “steam gunning”, “explosive relaxation”, “steam pretreatment”.
• the plant is quickly heated to high temperature (150 ° -250 ° C) by injection of steam under pressure. Stopping treatment is usually done by sudden decompression, called detente or explosion, which destructures the lignocellulosic matrix.
• the residence times vary from 10 seconds to a few minutes, for pressures ranging from 10 to 50 bars. This technique has been implemented either discontinuously or continuously.
• the implementation may be batch type, or continuous type.
• the steam explosion may be preceded by an acid impregnation to promote the hydrolysis of hemicelluloses during cooking.
• an acid impregnation to promote the hydrolysis of hemicelluloses during cooking.
• the steam explosion is applied to a previously acidified substrate, for example with rH 2 SO 4 , it leads to a solubilization and almost complete hydrolysis of hemicelluloses in their monomers, limiting degradation to furfural.
• the susceptibility of cellulose to enzymatic hydrolysis is improved.
• the use of an acidic catalyst makes it possible to reduce the temperature of the process (150 to 200 ° C. against 250 ° C. for the steam explosion without catalyst), and thus to minimize the formation of degradation compounds.
• the steam explosion may be preceded by an acidic cooking step which aims to hydrolyze the hemicelluloses and to remove them in a liquid solution in the form of monomeric sugars and / or oligomers.
• Important parameters include temperature, duration, presence of acid (type and concentration). These parameters act together on the reactivity of the substrate to enzymatic hydrolysis, and their effects are interchangeable to some extent. For example, a longer duration can compensate for a lower temperature.
• Biochemical processes for producing alcohols from lignocellulosic biomass include at least the following steps:
• pentoses means soluble monomers and oligomers of sugars comprising 5 carbon atoms and under the term “hexoses” the monomers and soluble oligomers of sugars comprising 6 carbon atoms.
• MS denotes the dry matter (solid and soluble) present in a medium and under the abbreviation “MES” the suspended matter (solids) present in a medium.
• MES the suspended matter
• the rate of solids is determined according to the method described by ASTM E1756-01 which consists of a mass loss at 105 ° C.
• alcoholic fermentation refers to the biological conversion of sugars into one or more alcohols and optionally mixed with ketones.
• the alcoholic fermentations according to the invention can be carried out anaerobically or aerobically in the presence of "wild" or “genetically modified” microorganisms.
• This term includes:
• Ethyl fermentation which corresponds to the production of ethanol alone by means of yeasts (eg S. cerevisiae) or bacteria (eg, Z mobilis) or other microorganisms.
• yeasts eg S. cerevisiae
• bacteria eg, Z mobilis
• ABE a fermentation "ABE" which corresponds to the production of a mixture comprising acetone, n-butanol (majority product), ethanol. Traces of isopropanol may also be present.
• alcoholic fermentation in the sense of the present invention includes ethyl, butyl, isobutyl fermentations but also other fermentations for the production of other alcohols.
• An object of the invention is therefore to provide a process for producing alcohols having two or more carbon atoms from biomass and for which the energy and water budgets are optimized.
• the method according to the invention comprises at least the following steps:
• step b) the enzymatic hydrolysis of the pretreated substrate contained in the effluent resulting from step a) is carried out in the presence of cellulolytic and / or hemicellulolytic enzymes so as to produce a hydrolyzate containing solubilized sugars;
• alcoholic fermentation is carried out solubilized sugars contained in the hydrolyzate from step b) into alcohols having two or more carbon atoms, in the presence of an alcoholic microorganism so as to produce a fermented effluent;
• a step is carried out for extracting alcohols having two or more carbon atoms from the fermented effluent resulting from stage c),
• a step e) in which at least one aqueous internal stream comprising at least one alcohol having n carbon atoms with n between 2 and 5 is recycled upstream of or into the pretreatment reactor, provided that when The alcohol comprises n 2 carbon atoms and is mixed with at least one other alcohol, so as to recover at the outlet of said pretreatment reactor a vapor phase effluent containing alcohols.
• the invention thus exploits the property of C 2 and C 3 alcohols to be more volatile than water and the property of the C 4 and C 5 alcohols to form an azeotrope with water and whose temperature of boiling is less than that of water and thus promote the distribution of these alcohols in the vapor phase during relaxation.
• the alcohols which are then sent to the extraction stage are already in vapor form, which makes it possible to reduce the energy cost of the separation by distillation and therefore the overall energy cost of the process.
• the other part of the alcohols that is not recovered in the vapor phase is found in the liquid effluent extracted from the pretreatment reactor and contributes to increasing the title of the wine or wines that are extracted from the main fermentation reactor.
• the recycled internal stream may advantageously and easily be thermally integrated into the overall scheme of the process according to the invention.
• the internal flow before being recycled can be preheated by means of a hot flow produced during the extraction step, which generally involves at least one distillation step.
• the process makes it possible to produce mainly alcohols preferably having 2, 3, 4 or 5 carbon atoms, alone or as a mixture.
• ethanol alone ethanol mixed with n-butanol
• ethanol mixed with isobutanol propanol alone or as a mixture
• isopropanol alone or as a mixture isobutanol alone or as a mixture
• n-butanol alone or as a mixture or possibly a mixture of the ABE type or a mixture of the IBE type.
• the internal flow which is recycled comprises alcohols chosen from ethanol, propanol, isopropanol and butanol, alone or as a mixture and provided that when the internal flow comprises ethanol it is mixed with at least one alcohol having 3 or 4 or 5 carbon atoms.
• the stream which is recycled upstream of or into the pretreatment reactor may comprise, for example, ethanol mixed with n-butanol, ethanol mixed with isobutanol, propanol alone or in a mixture, isopropanol alone or as a mixture, isobutanol alone or as a mixture, n-butanol alone or as a mixture, or optionally a mixture of the ABE type (acetone, n-butanol, ethanol) or a mixture of the IBE type ( isobutanol, n-butanol, ethanol).
• ABE type acetone, n-butanol, ethanol
• IBE type isobutanol, n-butanol, ethanol
• the method further comprises the following steps:
• a solid / liquid separation of at least a portion of a vinasse produced in step d) is carried out so as to recover a liquid fraction containing pentoses and
• the pentoses of the liquid fraction are fermented so as to provide said internal flow comprising alcohols.
• the method further comprises the following steps:
• a solid / liquid separation of at least a portion of the effluent resulting from step a) is carried out so as to recover a liquid fraction containing solubilized sugars and
• solubilized sugars of the liquid fraction are fermented so as to provide said internal flow comprising alcohols.
• the method further comprises the following steps: - Solid / liquid separation of at least a portion of the effluent obtained in step a) to recover a pulp;
• solubilized sugars contained in the liquid fraction are fermented so as to supply said internal flux comprising alcohols.
• the internal flow containing alcohols is derived from at least a part of the fermented effluent produced in step c).
• the internal flow containing alcohols is a liquid fraction obtained after solid / liquid separation of at least a part of the fermented effluent produced in step c).
• the internal flow containing alcohols is a liquid fraction obtained after washing a cake obtained by solid / liquid separation of at least a part of the fermented effluent obtained at step c).
• the method further comprises the following steps:
• a solid / liquid separation of at least a portion of the hydrolyzate obtained in step b) is carried out so as to recover a pulp containing hexoses and possibly pentoses and
• the hexoses and optionally pentoses contained in the pulp are fermented so as to provide said internal flow comprising alcohols.
• the internal flow containing alcohols is derived from a fermentation step of a liquid fraction obtained after a solid / liquid separation step of at least a part of the hydrolyzate obtained in step b).
• steps b) and c) are carried out in the same reactor.
• the internal flow containing alcohols is vaporized before the recycling step e).
• the cellulolytic and / or hemicellulolytic enzymes used during the hydrolysis step may be produced by a microorganism belonging to the genera Trichoderma, Aspergillus, Penicillium or Schizophyllum, or an anaerobic bacterium belonging to the genus Clostridium.
• the alcoholic microorganisms used in the conversion unit for carrying out the fermentation of hexoses to alcohols are preferably chosen from yeasts and bacteria, possibly genetically modified.
• microorganisms responsible for fermentation of the ethyl, butyl (ABE, IBE, ABEI) and isobutyl type are used.
• the microorganisms used for the butyl fermentation step are generally selected from strains belonging to the genus Clostridium (wild or genetically modified strains). These microorganisms are strictly anaerobic and capable of metabolizing hexoses and pentoses into butyl wine (ABE or IBE). They are also able to efficiently convert certain oligomers.
• the fermentation is usually done in batch mode, fed-batch and more interestingly, continuously.
• the temperature is between 30 and 39 ° C. and the pH is between 4 and 7.
• the microorganisms are preferably selected from the species Clostridium beijerinckii, Clostridium saccharobutylicum, Clostridium saccharoperbutylacetonicum and Clostridium acetobutylicum. All these microorganisms which may produce a mixture of acetone / butanol / ethanol or mixture ABE, or IBE if isopropanol replaces acetone.
• yeast or a bacterium is chosen. If yeast is used, Saccharomyces cerevisiae is the preferred one. It is also possible to choose yeasts such as Schizosaccharomyces pombe or Saccharomyces uvarum or diastaticus. More thermophilic yeasts, such as Kluyveromyces fragilis (now often referred to as K. marxianus) are also of interest, especially when enzymatic hydrolysis and ethyl fermentation are carried out simultaneously (SSF method).
• a genetically modified organism for example a yeast of the type Saccharomyces cerevisiae TMB 3400 (Ohgren et al., J.
• Biotech 126, 488-498, 2006 can also be used.
• This yeast makes it possible, in particular, to ferment in ethanol a part of the pentoses during the ethylic fermentation step of the hexoses, when the glucose is in a limiting concentration.
• the microorganism is a bacterium
• Zymomonas mobilis which has an efficient assimilation pathway.
• species of Zymomonas mobilis have been modified to convert pentoses to ethanol, for example the strain Zymomonas mobilis 8b described by Dutta et al. (Biotechnol Prog., 2010, Vol 26, No. 1, pp 64-72).
• the ethyl fermentation is preferably carried out at a temperature of between 30 ° C. and 40 ° C. and at a pH of between 3 and 6.5.
• the microorganisms which are used to produce the internal flow comprising alcohols from an internal flow comprising sugars can be preferably chosen from the microorganisms responsible for the ethyl or butyl or isobutyl fermentation such as those described above.
• an extractive fermentation also called extraction fermentation
• the fermentation reactor is completed by a device configured to extract on-line, in situ, in the presence of microparticles. organisms, at least part of the alcohols from the main fermentation.
• the goal is to continuously extract the fermentation inhibitor alcohols that are produced in order to maintain a high yield.
• Extraction techniques can be chosen from pervaporation, gas stripping, adsorption, perstraction, liquid / liquid extraction.
• the internal stream which is recycled can thus be a secondary stream resulting from an extractive fermentation using pervaporation, gas stripping or perstraction technology.
• Figure 1 is a schematic representation of a first embodiment of the process for producing alcohols according to the invention.
• Figure 2 is a schematic representation of a second embodiment of the process for producing alcohols according to the invention.
• Figure 3 is a schematic representation of a third embodiment of the process for producing alcohols according to the invention.
• Figure 4 is a schematic representation of a fourth embodiment of the process for producing alcohols according to the invention.
• Figure 5 is a schematic representation of a fifth embodiment of the process for producing alcohols according to the invention.
• Figure 6 is a schematic representation of a sixth embodiment of the process for producing alcohols according to the invention.
• the cellulosic and / or lignocellulosic substrate is introduced via line 1 into a preparation unit 2 of the load.
• the water and / or steam necessary for driving the charge preparation are introduced into the preparation unit by a dedicated line (not shown).
• Reagents e.g., acid
• the charge preparation comprises, for example, mechanical grinding, acid addition, adjustment of the "MS" by adding water in liquid form and / or steam before introduction into the steam explosion reactor.
• the cellulosic or lignocellulosic substrate used in the process according to the present invention can be chosen from the most varied biomasses, but more particularly from resinous tree species (softwood species such as spruces or pines) or hardwood species (hardwood species such as eucalyptus trees). or lignocellulosic agricultural waste (wheat straw, rice, etc.) or dedicated crops (miscanthus, switchgrass).
• the prepared substrate is introduced into the pre-treatment reactor 4, via line 3, which uses the steam explosion technique.
• the steam required for pretreatment is introduced through a pipe (not shown).
• the vapor phase generated at the expansion is extracted by the pipe 27.
• pretreatment The role of pretreatment is to make the cellulose accessible to enzymes, by destructuring the lignocellulosic matrix.
• pretreatment by steam explosion preferentially attack hemicellulose, which is found largely in the liquid phase at the output of the pretreatment.
• the pretreated substrate preferably contains between 5% by weight and 80% by weight of MS, more preferably between 15% by weight and 60% by weight of MS and even more preferably between 20% by weight and 55% by weight of MS.
• the pretreated substrate is directly sent via lines 5 and 7 to a conversion unit 8 which converts the cellulose into alcohols.
• This unit of The conversion comprises at least one enzymatic hydrolysis unit 9 and a fermentation unit 10 which may be, for example, butyl, isobutyl, ethyl or other alcohols.
• a fermentation unit 10 which may be, for example, butyl, isobutyl, ethyl or other alcohols.
• FIG. 1 the units for enzymatic hydrolysis and fermentation are shown separately from one another, but it is possible in the context of this embodiment to have a single reactor in which the reaction is carried out. hydrolysis and fermentation (SSF process) according to the fermentation chosen.
• SSF process hydrolysis and fermentation
• the conditions of the enzymatic hydrolysis mainly the solids content of the mixture to be hydrolysed and the amount of enzymes used, are chosen such that a solubilization of the cellulose of between 20% and 99% is obtained. preferred way between 30% and 95%.
• the water necessary to obtain the target MS level is added via a pipe (not shown).
• the desired level of MS is generally between 5% by weight and 45% by weight and preferably between 8% by weight and 40% by weight.
• the enzymatic hydrolysis is preferably carried out at a pH of between 4 and 5.5 at a temperature between 40 ° C. and 60 ° C.
• the necessary additives for example cellulolytic and / or hemicellulolytic enzymes, fermentation microorganisms (if the conversion reaction is in a single step), water, nutrients, chemical reagents such as soda and / or ammonia and / or potash, are introduced by a conduit (not shown) dedicated for this purpose.
• all or part of the pentoses can also be fermented, as may be the case when a bacterium of the genus Clostridium is used to carry out a fermentation butyl.
• a fermented must comprising a solid residue and a wine, is extracted via line 11, which is fed to a unit for extracting / purifying the alcohols contained in the wine.
• This extraction / purification step generally comprises at least one distillation step.
• the pulp is transferred to a solid / liquid separation unit from which a wet cake comprising cellulose, hemicellulose which has not been hydrolysed and lignin is recovered via line 16, and line 17, a clarified vinasse containing the unfermented sugars, for example unfermented pentoses (xylose, arabinose).
• the wet cake can either be reintroduced into the process, or recycled to produce energy, for example by methanation or combustion, or as an agricultural supplement (spreading).
• a fraction of clarified vinasse between 10% and 90% and preferably between 15% and 60% by weight, is sent via line 17 to an additional fermentation reactor 19.
• the pretreated substrate is extracted through line 5 and sent to a solid / liquid separation unit 6 (shown in dashed line).
• the solid / liquid separation unit 6 makes it possible to separate, via line 18, a liquid stream containing solubilized sugars during pre-treatment and a wet pulp which is sent via line 7 to the conversion unit 8.
• the solubilized sugars are derived essentially hemicellulose and include pentoses and possibly hexoses depending on the type of biomass treated.
• the liquid containing solubilized sugars is also sent via line 18 to the additional fermentation reactor 19.
• the reactor 19 is a fermentation reactor of pentoses and possibly hexoses residual alcohols.
• the microorganisms used for the fermentation of residual pentoses and hexoses may be bacteria, yeasts or fungi.
• the reactor 19 performs a fermentation of the ethyl, butyl type to produce a wine ABE (acetone, butanol, ethanol) or IBE (isopropanol, butanol, ethanol) or ABEI (acetone, butanol, ethanol, isopropanol).
• the microorganisms may be chosen from those of the genus Clostridium, bacteria which ferment pentoses very well. Another preferred possibility is to perform isobutyl fermentation with the microorganisms mentioned above.
• All or part of the wine produced by the fermentation reactor 19 is then transferred, via line 20, into a processing unit 21.
• the processing unit 21 may comprise, for example, a vaporization or heating device supplemented by a suspension material separation unit (eg by centrifugation and / or by decantation and / or by membrane treatment (ultrafiltration, microfiltration). ).
• a suspension material separation unit eg by centrifugation and / or by decantation and / or by membrane treatment (ultrafiltration, microfiltration).
• the effluent, in vapor or liquid form, coming from the processing unit 21, and essentially containing water and alcohols resulting from the fermentation (with a smaller amount of the compounds such as furfural, acetic acid) can be split into two streams, as shown in Figure 1.
• One of the streams 24 is then sent to the pre-treatment reactor 4 and / or to the reactor for preparing the biomass 2.
• the other part of the stream 23 may optionally be recycled in the distillation unit 12.
• An advantage of recycling the fraction 24 in the pretreatment reactor 4 and / or in the biomass preparation reactor 2 is that this recycle stream makes it possible to replace all or part of the makeup water required for these components. steps.
• the amount of alcohols recycled to the steam explosion reactor 4 is adjusted so as to obtain an alcohols content in the reactor 4 of less than 15% by weight, and preferably less than 10% by weight.
• Acetic acid, furfural and other compounds provided by the recycling have concentrations in the reactor 6 of less than 5%, or even less than 2% by weight.
• the processing unit 21 comprises at least one vaporization unit.
• the vaporization of the flow makes it possible to recycle only the volatile products, and thus to avoid the recycling of soluble products such as the residual sugars (hexoses and pentoses) which can degrade in the steam explosion reactor in furfural, 5 -HMF, or organic acids (formic, levulinic).
• the alcohols and optionally the other constituents mentioned above which are recycled in the pretreatment reactor 4 are recovered after the expansion phase in gaseous form with the steam via the pipe 27.
• the gaseous effluent is then transferred to a distillation unit 28 which produces at least two streams; a stream 29 which contains predominantly alcohols and a stream 30 mainly comprising water.
• the stream 29 can be reintroduced into the main extraction / separation unit 12 to be sent to a dedicated alcohol extraction / separation unit (not shown).
• the gaseous effluent recovered after expansion of the pre-treatment reactor 4 is sent directly to the extraction / separation unit 12.
• FIG. 2 represents another embodiment of the method according to the invention which differs from that presented in FIG. 1 by the fact that:
• the conversion unit 8 comprises an enzymatic hydrolysis reactor 9, a fermentation reactor 10 separated from that of the enzymatic hydrolysis and a solid / liquid separation device 31 placed between the said reactors 9 and 10;
• the flow containing alcohols which is recycled, is obtained from a pulp produced by solid / liquid separation of the hydrolyzate resulting from the enzymatic hydrolysis and which then undergoes a step of fermentation of the C 6 sugars and possibly C5 contained in said pulp.
• the hydrolyzate from the hydrolysis reactor is sent to the solid / liquid separation device 31 from which:
• a liquid stream 33 which is sent into the fermentation reactor 10 of alcohol.
• the pulp, via line 32, is sent to an additional fermentation reactor 19 hexoses and possibly pentoses.
• the reactor 19 is a fermentation reactor of the ethyl, butyl or isobutyl type.
• the solid residue extracted from the fermented must is removed from the process by the line 25.
• the pulp extracted from the pipe 32 is subjected to a washing step and solid / liquid separation to recover a juice containing hexoses (and optionally pentoses) and a wet cake.
• the wet cake either is removed from the process or is recycled to the fermentation reactor 10 while the sweet juice is sent to the fermentation reactor 19 to produce a wine which is then recycled to the pre-treatment reactor 4 and / or the reactor for preparing the biomass 2, possibly after treatment in a heating or vaporization unit 21.
• FIG. 3 A third embodiment is shown in FIG. 3. This variant differs from that of FIG. 2 in the following way:
• the solid / liquid separation unit 40 is disposed downstream of the conversion unit 8;
• the fermentation carried out in the reactor 10 is for example a fermentation of the butyl or isobutyl type (ABE, IBE or ABEI).
• a fraction (or part) of the fermented wort extracted from the fermentation reactor 10 (or from the conversion unit 8 in the case where an SSF process is implemented) is sent to a separation device solid / liquid 40.
• a separation device solid / liquid 40 From the solid / liquid separation device 40 is separated a wet cake by the line 41 and a liquid effluent containing wine by the line 42.
• the wet cake is returned in the distillation unit 12 while the wine (eg ABE or IBE or ABEI) is treated in a processing unit 21 (for example a vaporization unit) before being recycled to the pre-treatment reactor 4 and / or in the Biomass preparation reactor 2.
• the solid / liquid separation unit 40 is completed by a cake washing unit.
• the fermented must is separated into a liquid fraction (alcoholic wine) and a solid fraction containing a wet cake.
• the liquid fraction is sent to the main extraction / separation unit 12.
• the wet cake or pulp
• it is washed so as to recover a washing water containing more than 70% by weight, preferably more than 85% weight of the alcohols contained in the cake.
• the washing water is heated or vaporized in the treatment unit 21 before being recycled to the pretreatment reactor 4 and / or to the reactor for preparing biomass 2.
• the washed solid residue is recycled to the unit extraction / separation 12, is discharged out of the process.
• FIG. 4 shows another embodiment of the method according to the invention. This embodiment differs from that of FIG. 1 in that the effluent from the steam explosion pre-treatment reactor 4 is treated in a unit 50 consisting of a solid / liquid separation and washing unit. separating a washed wet cake (or pulp) and a liquid effluent containing essentially pentoses. The pulp is sent to the conversion unit 8 while the liquid effluent is fed through line 51 to the fermentation unit 19.
• This fermentation step like the diagram of FIG. for example perform a butyl fermentation (ABE, IBE or a mixture) pentoses.
• the wine which is withdrawn from the reactor 19 via the line 20 is sent to the processing unit 21 in order, for example, to vaporize it.
• the alcohol vapor is extracted via line 22 and is then recycled to the pre-treatment reactor 4 and / or to the biomass preparation reactor 2.
• FIG. 5 represents another embodiment of the method according to the invention which combines the embodiments of FIGS. 1 and 2. This embodiment implements a first solid / liquid separation step directly after the explosion step. steam and a second step of solid / liquid separation between the enzymatic hydrolysis and fermentation step.
• the pulp impregnated with liquid withdrawn from the steam pretreatment reactor 4 is sent to a solid / liquid separation device 6 from which a wet cake is extracted via line 7 and an aqueous effluent essentially containing pentoses via line 18.
• the aqueous effluent is treated in a fermentation unit 19 of pentoses to alcohols.
• the alcoholic wine obtained at the outlet of the fermentation unit 19 is for example vaporized in the processing unit 21 before being recycled to the reactor for preparing the biomass 2 and / or in the steam explosion pretreatment reactor 4.
• the conversion unit 8 which comprises an enzymatic hydrolysis reactor 9, a fermentation reactor 10 and a solid / liquid separation device 31 disposed between the hydrolysis reactor 9 and the fermentation reactor 10.
• the solid effluent impregnated with a juice essentially comprising hexoses (hydrolyzate) from the enzymatic hydrolysis reactor undergoes a solid / liquid separation step by means of the device 31 in order to extract via line 33 a liquid effluent which essentially closes hexoses and, via the line 32, a pulp containing a solid hydrolysis residue impregnated with hexose juice (with possibly pentoses).
• the pulp impregnated with hexose juice is transferred to a fermentation unit 60 which converts the hexoses to alcohols (e.g. ethanol, ABE IBE).
• the fermented must from the fermentation unit 60 is then treated in a unit 62 which successively comprises a solid / liquid separation device (optionally supplemented by washing means) and heating / evaporation means of the alcoholic wine obtained after separation. solid / liquid.
• a solid cake is extracted via line 63 while all or part of the alcoholic wine is recycled to the biomass preparation reactor 2 and / or to the steam explosion pre-treatment reactor 4 .
• the streams 18 and 32 are fermented in the same fermentation reactor.
• FIG. 6 represents a sixth embodiment of the method according to the invention.
• the hydrolyzate from the hydrolysis reactor is sent to the solid / liquid separation unit 31 from which:
• a liquid flow 33 containing hexoses which is sent to the fermentation reactor 10;
• the pulp extracted by the pipe 32 is subjected to a washing step and then solid / liquid separation in the unit 70 in order to recover the juice containing hexoses (and possibly pentoses) through the pipe 72 and a wet cake by the pipe 73.
• the wet cake is discharged out of the process while the sweet juice is returned to the fermentation reactor of sugars to alcohols.
• From the fermentation unit 10 is extracted by the pipe 1 1 a wine of which a fraction is extracted by the pipe 74 and sent to a vaporization unit 75 to produce a vapor.
• the steam thus generated is then recycled to the pre-treatment reactor 4 and / or to the biomass preparation reactor 2.
• the other fraction of the wine from the fermentation reactor 10 it is treated in the main distillation unit. 12 to separate the alcohols from the aqueous phase.
• Preparation of charge and pretreatment the wood is crushed and then introduced into the steam explosion reactor continuously, the MS of the solid at the explosion inlet is 55%.
• the pretreatment by steam explosion is carried out at 210 ° C for 5 minutes.
• the medium is suddenly expanded at a pressure of 1.3 atm.
• the steam consumption is 24 305 kWh per hour. 9.3% by weight of the mixture of the explosion reactor is recovered in the vapor phase at the expansion.
• the pretreated substrate is diluted to 10% solids and sent an enzymatic hydrolysis reactor, then in an ethyl hexose fermentation reactor, the fermentation microorganism is Saccharomyces cerevisiae, the conditions for carrying out the hydrolysis and the fermentation give yields of 22.9 g of ethanol per 100 g of MS introduced.
• the pentoses present are not converted by the fermentation microorganism chosen in this step, whereas the mannans resulting from hemicellulose are converted.
• the CO 2 extract is washed to recover the fraction of ethanol entrained in this flux.
• the ethanolic title of the stream sent for distillation is 26.9 g of ethanol / kg of liquid wine.
• the separation is by distillation on two columns, the first in the presence of solids.
• a network of heat exchangers makes it possible to thermally integrate the separation process.
• the first column consumes 30,480 kWh per hour at the reboiler.
• the reboiler of the second column consumes 3,170 kWh per hour.
• a vinasse / wine heat exchanger makes it possible to recover 27,160 kWh per hour of vinasse extracted from the first column.
• the net consumption of the ethanol recovery step is 33,650 kWh per hour, or 10.34 MJ / kg of ethanol extracted.
• the extraction yield is 99%.
• the microorganism used is Clostridium acetobutylicum. The operating conditions of the fermentation were adjusted to obtain a fermentation yield of 37 g of ABE mixture per 100 g of xylose, in proportion of 31.2% by weight of acetone, 62.5% by weight of butanol and 6.3%, respectively. % by weight of ethanol.
• the separation is carried out by distillation on two successive columns, the first column makes it possible to leave a more concentrated mixture of ABE, the second column makes it possible to obtain a mixture of acetone and ethanol at the top and butanol in the bottom, while part is withdrawn on a decanter tray to be recycled in the first column.
• the section is thermally integrated, and the respective consumptions of the two reboiler are 24 890 kWh per hour and 960 kWh per hour, plus 460 kWh per hour for the exchanger upstream of the first column.
• the specific consumption is 67.6 MJ / kg of mixed product.
• the process produces 94,730 tonnes of ethanol, 3,370 tonnes of acetone and 6,735 tonnes of butanol annually and has an average specific consumption of 23 MJ / kg of alcohols and solvents produced, including 16.3 MJ / kg. for distillations.
• the pretreated substrate is diluted to 10% solids and sent to an enzymatic hydrolysis reactor and then to an ethyl hexose fermentation reactor.
• the fermentation microorganism is Saccharomyces cerevisiae and the conditions for carrying out hydrolysis and fermentation give yields of 22.9 g of ethanol per 100 g of MS introduced.
• the pentoses present are not converted by the fermentation microorganism chosen in this step, whereas the mannans resulting from hemicellulose are converted.
• the CO 2 extracted is washed to recover the fraction of ethanol entrained in this stream.
• the ethanol concentration of the stream sent for distillation is 26.9 g of ethanol / kg of liquid wine.
• the separation is carried out by distillation on two columns, the first distillation being carried out in the presence of solids.
• a network of heat exchangers makes it possible to thermally integrate the separation process.
• the first column consumes 30,480 kWh per hour at the reboiler.
• the reboiler of the second column consumes 3,170 kWh per hour.
• a vinasse / wine heat exchanger makes it possible to recover 27,160 kWh per hour from the vinasses extracted from the first column.
• the net consumption of the ethanol recovery step is 33,650 kWh per hour, or 10.34 MJ / kg of ethanol extracted.
• the extraction yield is 99%.
• the vinasses containing the pentoses are sent to a solid / liquid separator, the clarified vinasses, which represent 84.6% of the initial flux, are then sent to a BUTYL fermentation of the pentoses.
• the microorganism used is Clostridium acetobutylicum.
• the operating conditions of the fermenter are adjusted so as to obtain a fermentation yield of approximately 37 g of ABE mixture per 100 g of xylose and produce a wine having a proportion of 31.2% by weight of acetone, 62.5% by weight of butanol and 6.3% by weight of ethanol.
• the vapor stream from the pretreatment and containing ⁇ is introduced into the first column.
• the section is thermally integrated, and the respective consumptions of the two Reboilers are 17,260 kWh per hour and 1,130 kWh per hour. Specific consumption is 47.2 MJ / kg of blended product.
• the fraction of the butyl wine that is sent to the steam pretreatment is first vaporized by bringing the butyl wine to 39 bar and then heated to 390 ° C, and finally expanded to 38 bar, to separate the vapor phase (more 99% of the flux) and a liquid stream containing the residues of the fermentation.
• the vapor stream is injected into the steam explosion reactor. In which there is no additional addition of steam.
• the energy consumption to vaporize this flow is 28 035 kWh per hour, after a preheating at 90 ° C by exchange with the condenser of the first separation column of the ABE.
• the process produces 94,800 tonnes of ethanol per year, 3,300 tonnes of acetone and 6,735 tonnes of butanol, with an average specific consumption of 22 MJ / kg of alcohols and solvents produced, of which 14.3 MJ / kg for distillations. This represents an energy gain of 13% on the distillation section and 5% on the entire process.
• Load Straw, flow 81 tons / hour (dry matter basis), average composition:
• Enzymatic hydrolysis At the output of the pretreatment, 726 tons / hour of water are added to the solid and the mixture is sent to enzymatic hydrolysis where 95% of the cellulose is converted into glucose and 80% of the hemicellulose into xylose. At the outlet of the enzymatic hydrolysis, the hydrolyzate is sent to a solid / liquid separator.
• the hydrolyzate is separated by a solid / liquid separator into a liquid stream (810 tons / hour) and a solid pulp (96 tons / hour including 62.6 tons / hour of water).
• the solid pulp is then washed in a 3-stage countercurrent washing system with a water flow rate of 147 tons / hour, which makes it possible to recover 94.6% of the monomeric sugars of the liquid phase of the pulp in the washing juice.
• the liquid flow and the washing juice are mixed and then introduced into a fermentation reactor hexoses and pentoses isobutanol. 90% of hexoses and 45% of pentoses are converted to iso-butanol, the flow at the output of fermentation has a flow rate of 957 tons / hour and a concentration of 17 g / liter of iso-butanol.
• the separation is done by distillation on two columns, with a decanter interposed between the two columns.
• a network of heat exchangers makes it possible to thermally integrate the separation process.
• the first column makes it possible to separate the water / iso-butanol azeotrope from the wine at the top of the column, which is then condensed and then cooled to 60 ° C. and sent to a decanter in which the liquid / liquid separation is carried out in order to recover a phase. rich in water which is returned to the first distillation column, and a phase rich in iso-butanol which is sent to the second column.
• the second column makes it possible to recover the purified iso-butanol in the bottom and at the top the water / iso-butanol azeotrope which is returned to the clarifier.
• the first column consumes 42,125 kWh per hour to the reboiler.
• the reboiler of the second column consumes 37 to 10 kWh per hour.
• a vinasse / wine heat exchanger makes it possible to recover the heat equivalent to 62,000 kWh per hour of the vinasses extracted from the first column.
• the net consumption of the recovery stage of the iso- Butanol is 79 235 kWh per hour, ie 17.9 MJ / kg of iso-butanol extract.
• the extraction yield is 99.5%.
• the process makes it possible to produce 127 750 tonnes of iso-butanol annually with a specific consumption of 28.3 MJ / kg of iso-butanol, of which 17.9 MJ / kg for the distillation.
• Preparation of charge and pretreatment the straw is crushed, the MS regulated at 45% by addition of water, then the mixture is introduced into the steam explosion reactor continuously.
• the pretreatment by steam explosion is carried out at 200 ° C for 3 minutes.
• the medium is suddenly expanded at a pressure of 1.3 atm.
• Enzymatic hydrolysis At the end of pre-treatment, 733 tonnes / hour of water are added to the solid and the mixture is then sent to enzymatic hydrolysis in which 95% of the cellulose is converted into glucose and 80% of the hemicellulose into xylose. At the outlet of the enzymatic hydrolysis, the hydrolyzate is sent to a solid / liquid separator.
• the hydrolyzate is separated by a solid / liquid separator into a liquid stream (813 tons / hour) and a solid pulp (95 tons / hour including 61 tons / hour of water).
• the solid pulp is then washed in a 3-stage countercurrent washing system with a water flow rate of 147 tons / hour, which makes it possible to recover 94.5% of the monomeric sugars from the liquid phase of the pulp in the juice. washing.
• the liquid flow and the washing juice are mixed and then introduced into a fermentation reactor hexoses and pentoses isobutanol. 90% of the hexoses and 45% of the pentoses are converted to iso-butanol, the flow at the output of fermentation has a flow rate of 958 tons / hour and a concentration of 17 g / liter of iso-butanol.
• the separation is done by distillation on two columns, with a decanter interposed between the two columns.
• a network of heat exchangers makes it possible to thermally integrate the process of separation.
• the first column makes it possible to separate the water / iso-butanol azeotrope from the wine at the top of the column which is then condensed and then cooled to 60 ° C. and sent to a decanter where the liquid / liquid separation is carried out so as to recover a rich phase. water which is returned to the first distillation column, and a phase rich in iso-butanol which is sent to the second column.
• the second column makes it possible to recover the purified isobutanol in the bottom and at the top the water / iso-butanol azeotrope which is returned to the clarifier.
• the first column consumes 27,430 kWh per hour at the reboiler, the other part of heat being provided by the steam flow from the pretreatment.
• the reboiler of the second column consumes 37,410 kWh per hour.
• a vinasse / wine heat exchanger makes it possible to recover 62,000 kWh per hour of vinasse extracted from the first column.
• the net consumption of the isobutanol recovery step is 64,840 kWh per hour, ie 14.6 MJ / kg of isobutanol extract.
• the extraction yield is 99.5%.
• iso-butanol fermentation reactor At the outlet of the iso-butanol fermentation reactor (ISO-BUTYL fermentation), a part (6% by weight of the wine extracted from the fermentation reactor) of the butyl wine is used as an internal recycling stream in the explosion reactor. steam. This fraction is first raised to 39 bar and heated to 380 ° C, then expanded to 38 bar, to separate the vapor phase (more than 99% of the flow) and a liquid stream containing the residues of the fermentation. The vapor stream is then injected into the steam explosion reactor in which there is no additional steam addition. The energy consumption to vaporize this flow is 45 940 kWh per hour.
• the process makes it possible to produce 127 750 tonnes of iso-butanol annually and with a specific consumption of 24.9 MJ / kg of iso-butanol, of which 14.6 MJ / kg for the distillation. This represents an energy gain of 19% on the distillation section and 12% on the entire process.

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