Method for treating lignocellulosic biomass

Abstract

The invention relates to a lignocellulosic biomass treatment: - a) a pretreatment step (2), in order to obtain a pretreated biomass (3), - b) a first step of solid / liquid separation (3a) of the pretreated biomass (3) obtained in step a) to give a first solid fraction (7) of pretreated biomass and a first liquid fraction (6) comprising a mixture of compounds comprising C5 sugars and C6 sugars, partly in monomeric form and partly in oligomeric form, - c) a first step of enzymatic hydrolysis (14) of the first solid fraction (7) of pretreated biomass obtained in step b), in order to obtain a hydrolysate (15) in the form of sugar(s), - d) a step (24) of treating said first liquid fraction (6) obtained in step b) by hydrolysis, so as to obtain a treated fraction (26) which is enriched in C5 sugars in monomeric form and / or in C6 sugars in monomeric form.

Description

[0001] PROCESS FOR TREATING LIGNOCELLULOSIC BIOMASS

[0002] Technical field

[0003] The present invention relates to the treatment of sweet juices, in particular those known as second generation (2G), which can be obtained from lignocellulosic biomass.

[0004] These sugary juices can be used to produce other products by chemical or biochemical means (for example alcohols such as ethanol, butanol, or other molecules, for example solvents such as acetone, intermediate products used in the chemical industry, etc.), in particular as substitutes for petrochemical derivatives.

[0005] Prior art

[0006] Lignocellulosic biomass represents one of the most abundant renewable resources on Earth. The substrates considered are very varied, they concern both woody substrates such as different woods (hardwoods and softwoods), co-products from agriculture (wheat straw, corn cobs, etc.) or other industries, such as the food industry, paper, etc.

[0007] Different types of processes exist for converting lignocellulosic biomass into sugary juices depending on the type of biomass. In the case of sacchariferous plants (sugar beet, sugar cane) or starchy plants (corn and wheat), so-called first-generation (1G) sugary juices are obtained, for example through extraction operations.

[0008] If it is biomass of the agricultural, forestry or paper residue type, so-called second generation (2G) sweet juices are obtained by a biochemical transformation process which generally includes a pretreatment step and an enzymatic hydrolysis step using an enzymatic cocktail. The pretreatment most often includes an impregnation step using an acidic, basic or oxidizing liquor, then cooking of the impregnated biomass which is possibly accompanied by a steam explosion. The sweet juices resulting from the hydrolysis can then be further treated, for example by fermentation to convert them into alcohol, and the process also includes separation and / or purification steps.

[0009] These sweet juices can also come from a mixture of sweet juices from different types of biomass.

[0010] Lignocellulosic biomass is composed of three main polymers: cellulose (35 to 50% by weight), which is a polysaccharide consisting mainly of hexoses; hemicellulose (20 to 30% by weight), which is a polysaccharide most often consisting mainly of pentoses; and lignin (15 to 25% by weight), which is a polymer with a complex structure and high molecular weight, composed of aromatic alcohols linked by ether bonds. These different molecules are responsible for the intrinsic properties of the plant wall and are organized into a complex tangle.

[0011] Among the three basic polymers that integrate lignocellulosic biomass, cellulose and hemicellulose are those that allow the production of 2G sweet juices.

[0012] Most often, hemicellulose is mainly broken down into sugars during pretreatment, and the cellulose is converted into glucose by enzymatic hydrolysis. However, access to raw cellulose remains difficult for enzymes, hence the need for the pretreatment mentioned above. This pretreatment makes it possible to modify the physicochemical properties of lignocellulosic biomass in order to improve the accessibility of cellulose to enzymes and its reactivity to enzymatic hydrolysis.

[0013] Many technologies of interest to the invention for carrying out this pretreatment exist, which will be grouped hereinafter under the generic term of "cooking": acid cooking, alkaline cooking, cooking by auto-hydrolysis, steam explosion, processes called "organosolv pulping" according to the known English term (or treatment with organo-solvent in French). This last process concerns a pretreatment in the presence of one or more organic solvents and generally water. The solvent can be an alcohol (ethanol), an acid such as acetic acid, formic acid, or even acetone.

[0014] Different configurations are reported for example in the document “Production of bioethanol from lignocellulosic materials via the biochemical pathway: A review”, M. Balat, Energy Conversion and Management 52 (2011) 858-875, or in the document “Bioethanol production from agricultural wastes: an overview”, N. Sarkar, S. Kumar Ghosh, S. Bannerjee, K. Aikat, Renewable Energy 37 (2012) 19-27.

[0015] One of the most effective pretreatments is steam explosion, especially under acidic conditions, which allows almost complete hydrolysis of hemicellulose and a significant improvement in the accessibility and reactivity of cellulose to enzymes. This pretreatment may be preceded by other treatment(s).

[0016] Thus, the pretreatment can generally comprise three stages which are the preparation of liquor, the impregnation of the biomass with this liquor and the pretreatment of the impregnated biomass, for example by cooking possibly coupled with a steam explosion: Patent FR 3 075 203 describes a process with impregnation of the biomass with an acid liquor, then cooking and steam explosion of the impregnated biomass, with an adjustment of the acidity of the acid liquor and a recycling of the latter. Patent FR 3 075 201 also describes a process for pretreatment of the biomass by acid impregnation then steam explosion, with in addition a washing of the means of feeding the reactors and recycling of the washing water in the process.

[0017] Patent FR 3 075 201 also describes a process for pre-treating biomass by acid impregnation followed by steam explosion, with, in addition, washing of the reactor feed means and recycling of the wash water in the process.

[0018] A solid / liquid separation can then be carried out on the pre-treated biomass, in order to recover a liquid fraction which is a sweet juice in the aqueous phase, and a solid fraction, which is a pre-treated marc also called cake.

[0019] Patent FR 3 083 126 thus describes a liquid / solid separation operation on the pretreated biomass obtained at the end of the pretreatment step or at the end of an additional step of said pretreated biomass, this separation step comprising two successive sub-steps:

[0020] - an upstream sub-step b1 of contacting the solid / liquid mixture implemented by a continuous mixer using a mixing fluid,

[0021] - and a downstream extraction / washing sub-step b2 implemented by a continuous filter, in particular of the belt filter type, using a washing fluid, to obtain a solid phase enriched in solid and a plurality of liquid phases enriched in liquid, with operation of the filter preferably in counter-current between the circulation of the solid / liquid mixture to be separated and the extraction / washing fluid, and at least partial recycling of a liquid phase extracted from the belt filter at the inlet of the mixer as a mixing fluid.

[0022] The sweet juices thus obtained from lignocellulosic biomass, in particular after its pretreatment or after enzymatic hydrolysis in the case of so-called 2G sugars, are in the form of a mixture of sugars in the aqueous phase, where we find so-called C5 sugars (i.e. with 5 carbons), such as xylose and arabinose, and so-called C6 sugars (i.e. with 6 carbons), such as glucose, mannose and galactose.

[0023] Particularly in the case of type 2G sweet juices resulting from the pretreatment of lignocellulosic biomass, we observe for the majority of lignocellulosic biomasses, in the sweet juice, a proportion of C5 sugars higher than that of C6 sugars. By sweet juice, we mean that sugars are released by the pretreatment, and that they can be solubilized by mixing the pretreated biomass with water for example.

[0024] The sugars in sweet juice, as seen above, are mostly, if not exclusively, C5 and C6 sugars. In fact, they can be found in three different forms:

[0025] - in a polymeric form, with a high degree of polymerization, greater than 6, that is to say that they have not been converted, they are insoluble in water, this is the case of cellulose,

[0026] - in monomeric form, they are soluble in water

[0027] - in an oligomeric form, that is, the sugars are in a polymeric form, but with a low degree of polymerization, between 2 and 6, they are also soluble in water.

[0028] This means that, after pretreatment of the biomass, and after having carried out a solid / liquid separation of the biomass thus treated, the liquid fraction obtained is a sweet juice with sugars in monomeric and oligomeric form. The sugars in polymeric form, insoluble, are found in the solid fraction.

[0029] The proportion of C5 sugars compared to C6 sugars, and the proportion, for each of these types of sugars, of the oligomeric form compared to the monomeric form are variable, notably depending on the nature of the biomass (straw, wood, etc.), depending on the type and severity of the pretreatment, depending on the washing conditions when there is washing, etc. But in most cases, there is indeed a significant content of sugars in oligomeric form in the sweet juices.

[0030] However, the presence of these sugars in oligomeric form can be detrimental, regardless of the intended application for these sweet juices. Indeed, when the aim is to convert these sweet juices into other compounds, whether by chemical or biochemical conversion (fermentation for example), sugars in monomeric form are more reactive than sugars in oligomeric form. And while there are outlets for sweet juices as is, without further conversion, these must generally meet data specifications, including a high monomeric sugar content.

[0031] There is therefore a need to improve the quality of these sweet juices, and in particular to increase the sugar content in monomeric form or to reduce the sugar content in oligomeric form.

[0032] The invention therefore aims to obtain sweet juices with a high sugar content in monomeric form. It also aims to integrate this production of sugars with a high sugar content in monomeric form into a line for producing sugar or alcohol from lignocellulosic biomass, in order to improve its operation or performance, in particular so as to obtain a higher quality of sweet juice in the case of sugar production, and / or so as to obtain a higher conversion rate into alcohol in the case of alcohol production and / or so as to obtain a process that is more economical in terms of utilities or energy. Summary of the invention

[0033] The invention firstly relates to a method for treating lignocellulosic biomass, said method comprising

[0034] - a) a biomass pretreatment step, comprising cooking the biomass, possibly accompanied by a steam explosion, to obtain a pretreated biomass

[0035] - b) a first step of solid / liquid separation of all or part of the pretreated biomass obtained in step a) into a first solid fraction of pretreated biomass and a first liquid fraction comprising a mixture of compounds, in particular in aqueous phase, comprising C5 sugars with 5 carbons and C6 sugars with 6 carbons, said C5 sugars and / or said C6 sugars being partly in monomeric form and partly in oligomeric form

[0036] - c) a first step of enzymatic hydrolysis of the first solid fraction of pretreated biomass obtained in step b), to obtain a hydrolysate in the form of sugar(s), including C6 sugars with 6 carbons,

[0037] - d) a step of treating said first liquid fraction obtained in step b) by hydrolysis under acidic conditions and / or by a second enzymatic hydrolysis, in order to obtain a first treated liquid fraction which is enriched in C5 sugars in monomeric form and / or in C6 sugars in monomeric form and depleted in C5 sugars in oligomeric form and / or in C6 sugars in oligomeric form.

[0038] For the sake of brevity, in this text, sugars with 5 carbons will be referred to as C5 sugars, and sugars with 6 carbons as C6 sugars, and the first liquid fraction to be treated according to the invention in step d) may also be referred to, for the sake of brevity, by the term "juice" or "sweet juice" or "initial juice": This is a mixture of compounds including C5 and C6 sugars in the aqueous phase and soluble in water.

[0039] Generally in this text, unless expressly stated otherwise, all liquid fractions are aqueous.

[0040] For the purposes of the invention, the term "depleted" means that the concentration (or content) of the oligomeric sugar in question in the mixture decreases due to the treatment and "enriched", conversely, means that the concentration of the monomeric sugar in the mixture increases due to the treatment. For the purposes of the invention, the term "sugars" generically means sugars which may be in both their monomeric and oligomeric form, unless otherwise specified.

[0041] Preferably, the first liquid fraction contains sugars derived mainly, in particular entirely, from the depolymerization of hemicelluloses present in the lignocellulosic biomass. This first fraction is a sweet juice obtained without the addition of enzymes, and obtained following the pretreatment of a lignocellulosic biomass.

[0042] The invention has thus developed and integrated into a biomass conversion process a treatment of a sugary juice which will transform at least part of the sugars in oligomeric form into sugars in monomeric form, by acid hydrolysis, preferably hot, or by enzymatic hydrolysis.

[0043] The invention has therefore developed a hydrolysis treatment which will transform at least part of the sugars in oligomeric form into sugars in monomeric form. What is very advantageous is that we thus manage to reduce / remove the undesirable compounds, namely the sugars in oligomeric form, to convert them into sugars in monomeric form, which are the desired products: it is not simply a matter of removing them from the initial sugary juice, but of converting them to the desired form.

[0044] And this hydrolysis is divided into chemical hydrolysis, with acidic conditions, preferably hot, or biochemical, with enzymes. They can of course be combined, but a single hydrolysis operation has proven to be entirely sufficient to obtain convincing results:

[0045] The conversion efficiency of oligomers into monomers obtained with the treatment according to the invention, whatever the type of chemical or biochemical hydrolysis chosen, can in fact reach up to 50% and more.

[0046] The invention therefore "intercalates" a stage of treatment of the sugary juice obtained at the end of pretreatment in a biomass treatment process aimed at converting it into sugars and then possibly into alcohol, and which provides, in a known manner, a pretreatment of the biomass then its enzymatic hydrolysis, then its possible fermentation: this opens the way to a quantity of new possibilities of valorization, product quality and biomass conversion yield, as detailed below.

[0047] The conditions of this hydrolysis, in particular the acidity of the medium and the temperature in the case of acid hydrolysis, or the content and nature of the enzymes in the case of enzymatic hydrolysis, the duration of the treatment etc. are adjusted according to, in particular,

[0048] - the nature of the biomass,

[0049] - the type of pretreatment a) that it has had, data which determine the oligomer content of the mixture,

[0050] - or even purity specifications in monomeric sugar if it is used as is.

[0051] The severity of the treatment can thus be modulated according to the sugar juice to be treated and the purity of monomeric sugar to be achieved, by modulating the different operating conditions of the hydrolysis treatment of step d).

[0052] And what is particularly advantageous is that the severity of the conditions of the pretreatment a) of the biomass can also be modulated according to that of the hydrolysis conditions of the treatment step d). Thus, if treatment conditions according to the invention are adopted that are sufficiently severe, then it is possible to "afford" to reduce the severity of the pretreatment of the biomass, for example by impregnating it with a less acidic solution, by cooking it at a lower temperature, without ultimately negatively impacting the sugar / alcohol production yield of the overall biomass conversion process.

[0053] Indeed, if less severe operating conditions are chosen for the pretreatment, there is a tendency to form fewer possible degradation compounds, possibly to the benefit of more oligomeric sugars, but which will themselves be reconverted into monomeric sugars with the hydrolysis treatment of the invention.

[0054] And this can be very interesting economically (for example, reduction in acid consumption during the impregnation of biomass, reduction in energy consumption for cooking impregnated biomass), on an industrial scale, without negatively impacting production yields in sugar or alcohol.

[0055] According to a first embodiment, the treatment step d) is a hydrolysis step under acidic conditions preferably carried out at a temperature of at least 60°C, in particular at least 70°C, in particular at least 75°C, or at least 80°C, or at least 90°C, or at least 100°C, and preferably at most 140°C, in particular at most 130°C. It is in fact very effective to carry out the hydrolysis “hot”, at at least 60°C, but it is preferable not to raise the temperature of the sugary juice too high, in order to avoid any parasitic reaction of the Maillard reaction type which would degrade the sugars.

[0056] According to said first embodiment, the treatment step d) is a hydrolysis step under acidic conditions preferably carried out so that there is at least 0.1% by weight of acid in said first liquid fraction, in particular between 0.2 and 2.8% by weight of acid in said mixture, and / or with a pH of at most 4.5, and preferably between 0.5 and 2.5.

[0057] According to said first embodiment, the treatment step d) is a hydrolysis step under acidic conditions preferably carried out so that there is at least 0.1% by weight of acid in the total mixture M (sugars + water), in particular between 0.2 and 2.8% by weight of acid in said mixture. The acid contents in the total mixture M (sugars + water) correspond to an addition of acid to the initial sweet juice.

[0058] Advantageously, the acid in question is preferably chosen from at least one of the following strong acids: sulfuric acid, hydrochloric acid and / or at least one of the following organic acids: acetic acid, oxalic acid, formic acid, etc. The acid may also be in the form of a solution of acid diluted in water.

[0059] Advantageously, the hydrolysis step under acidic conditions carried out according to the invention is carried out at a pH preferably of at most 4.5, in particular of at most 4 or of at most 3.5 or of at most 3.

[0060] It is preferably chosen between 0.5 and 2.5.

[0061] According to a second embodiment of the invention, the treatment step d) is a second enzymatic hydrolysis step carried out at a temperature of at most 80°C or at most 70°C, in particular at least 20°C, and is preferably between 40 and 60°C.

[0062] According to said second embodiment of the invention, the treatment step d) is an enzymatic hydrolysis step preferably carried out at a pH of at least 3, in particular at least 3.5, in particular at least 4, and preferably at most 6. It is in fact in this pH range that the enzymes tend to be the most effective.

[0063] To obtain this pH, it may be necessary to adjust the pH of the initial mixture M by adding acid or base, in particular by adding base, preferably KOH or NaOH, when the pH of the initial mixture M is less than or equal to 3. This is particularly the case when the juice comes from a pretreatment with acid impregnation of biomass, and therefore strongly acid (with a pH which may be of the order of 2 or less).

[0064] According to said second embodiment of the invention, the treatment step d) of enzymatic hydrolysis is carried out by adding to the initial mixture (juice) M a quantity of enzymes corresponding to at least 0.05 g protein / kg of mixture, in particular to at least 0.08 g protein / kg of juice for a concentration of 50 g of monomeric sugars / kg of juice, and preferably corresponding to at most 2 or 3 g protein / kg of mixture at the same concentration of monomeric sugars in the mixture. According to this second embodiment, the treatment step d) is an enzymatic hydrolysis step, and it may comprise a sub-step d1) of separation of the enzymes from the first treated liquid fraction, in order to obtain on the one hand a first treated and separated liquid fraction, and on the other hand an enzyme fraction.Very advantageously, this fraction of enzymes can be at least partly recycled to step d): it may be necessary to provide a fresh supply of enzymes, in addition to the recycled fraction, to carry out step d), in particular if the activity of the enzymes decreases progressively. Note that in this text, the so-called treated fraction is considered to also include the treated and separated fraction, when enzymatic hydrolysis with separation of the enzymes at the end of hydrolysis has been chosen.

[0065] Any known technique can be used to separate enzymes. For example, a plate filter can be used, or microfiltration or ultrafiltration membranes can be used (where separation is achieved by sieving, due to the difference in size between the components to be separated and the size of the membrane pores).

[0066] Advantageously, the acid or enzymatic hydrolysis treatment of step d) can be carried out continuously, in fed batch or batch, in particular in a stirred or piston-type reactor.

[0067] According to a variant of the invention, only a first part of the pretreated biomass obtained in step a) is conducted to the first step b) of solid / liquid separation, and a second part of the pretreated biomass is conducted directly to step c) of first enzymatic hydrolysis. The first enzymatic hydrolysis can then be carried out on the two types of streams at the same time, one coming directly from the pretreatment, the other having passed through a solid / liquid separation step, the relative proportion of the stream from the pretreated biomass which goes to the solid / liquid separation and of the stream from the pretreated biomass which goes directly to the enzymatic hydrolysis is adjustable, for example between a relative proportion of 90 / 10 to 10 / 90 by weight. It is also possible to provide that 100% of the biomass stream passes through the step b) of solid / liquid separation before enzymatic hydrolysis.

[0068] We can thus jointly carry out the first enzymatic hydrolysis at the same time

[0069] - on the solid residue resulting from the solid / liquid separation b), because this residue still contains compounds convertible into sugars by enzymatic hydrolysis,

[0070] - and on pretreated biomass resulting directly from the pretreatment, which makes it possible to maintain a high conversion yield by enzymatic hydrolysis compared to the initial quantity of biomass, despite the removal of a portion of pretreated biomass to recover the soluble sugars. Step b) of solid / liquid separation may, according to a preferred embodiment, comprise a first step of contacting the pretreated lignocellulosic biomass and a contacting fluid, preferably water, then a second step of filtration, and optionally washing.

[0071] When step b) of solid / liquid separation comprises a step of contacting the pretreated biomass with a fluid and then a washing step, this can be carried out in co-current or counter-current mode, in particular using part of the recovered liquid fraction as washing and / or contacting fluid. Preferably, the contacting fluid is part of the recovered liquid fraction and the washing fluid is water.

[0072] Step b) of solid / liquid separation can, according to a preferred embodiment, be carried out on a filtration unit, in particular a belt filter or a filter press, by centrifugation or by decantation.

[0073] The process according to the invention may also comprise a step e) of fermentation by second microorganisms of the hydrolyzate in the form of sugar(s) obtained in step c), in order to obtain a fermented biomass comprising at least one alcohol, in particular ethanol. This is then a process for producing ethanol-type alcohol which can be used as biofuel.

[0074] And in this case, according to a preferred embodiment, the enzymatic hydrolysis steps c) and fermentation e) can be carried out simultaneously. This is called SSCF for "Simultaneous Saccharification and Co-Fermentation" in English.

[0075] The method according to the invention may also comprise a step f) of producing enzymes from first microorganisms, in particular fungi, in order to use said enzymes to ensure the first enzymatic hydrolysis of step c).

[0076] And in this case, all or part of the first liquid fraction once treated in step d) can be sent as a substrate for the growth of the first microorganisms and / or for the production of enzymes by said microorganisms. This is the case where the process integrates in situ production of enzymes to carry out the enzymatic hydrolysis of the pretreated biomass (the other alternative being to bring enzymes produced on another site to the production site).

[0077] The method according to the invention may also comprise a step i) of propagation of second fermentation microorganisms, in order to use said microorganisms, in particular yeasts, to ensure the fermentation of step f) when it is planned. This is the case where the microorganisms are propagated in situ, on the biomass treatment site. And in this case, all or part of the first liquid fraction once treated in step d) may be sent to said step i) as a substrate for propagation of said third microorganisms.

[0078] Preferably, the first microorganisms used in step f) and optionally the second microorganisms used in steps i) and e) are chosen from yeasts, bacteria, fungi, and preferably from yeasts in the genus Saccharomyces, in particular the species Saccharomyces cerevisae or, among bacteria, in the genus Corynebacterium.

[0079] Preferably, the first microorganisms are chosen from fungi, in particular filamentous fungi, preferably those of the genus Trichoderma, in particular Trichoderma reesei.

[0080] According to a preferred embodiment, the pretreatment according to step a) of the biomass comprises

[0081] - a1) a sub-step of impregnation of the biomass (1) with a liquor, in particular acid, to obtain an impregnated biomass

[0082] - a2) a sub-step of cooking the impregnated biomass, possibly accompanied by a steam explosion, to obtain a pre-treated biomass (3).

[0083] When the process of the invention comprises step f) of fermentation, it may also comprise:

[0084] - a step j) of separation, in particular by distillation (21), of the fermented biomass in the form of alcohol obtained in step f), with a possible step k) of solid / liquid separation of the fermented biomass before or after said separation step j).

[0085] The invention also relates to a plant for treating lignocellulosic biomass using the method described above.

[0086] The invention also relates to an installation for treating lignocellulosic biomass, said installation comprising

[0087] - a) a biomass pretreatment unit, comprising a biomass cooking device, possibly accompanied by a steam explosion, to obtain pretreated biomass

[0088] - b) a first solid / liquid separation unit, comprising in particular a filtration device, of all or part (3a) of the pretreated biomass (3) obtained in unit a) into a first solid fraction (7) of pretreated biomass and a first liquid fraction (6) comprising a mixture of compounds, in particular in aqueous phase, comprising C5 sugars with 5 carbons and C6 sugars with 6 carbons, said C5 sugars and / or said C6 sugars being partly in monomeric form and partly in oligomeric form

[0089] - c) a unit for enzymatic hydrolysis of the first solid fraction of pretreated biomass obtained in step b), to obtain a hydrolysate in the form of sugar(s), including C6 sugars with 6 carbons,

[0090] - a unit for treating said first liquid fraction (6) obtained in step b) by hydrolysis under acidic conditions and / or by enzymatic hydrolysis, in order to obtain a first treated liquid fraction which is enriched in C5 sugars in monomeric form and / or in C6 sugars in monomeric form and depleted in C5 sugars in oligomeric form and / or in C6 sugars in oligomeric form.

[0091] For the purposes of the invention, the first and second microorganisms mentioned above may be a single type of microorganism or a combination of different microorganisms. Similarly, for the purposes of the invention, the enzymes may be of the same type or, preferably, be a mixture of enzymes of different type / function which may also be called an enzyme “cocktail”.

[0092] The biomass of interest to the invention and from which the first liquid fraction comprising C5 sugars with 5 carbons and C6 sugars with 6 carbons is derived, is of the lignocellulosic type, originating in particular from forestry and / or agricultural and / or paper residues, and / or from sacchariferous plants and / or from starchy plants and / or from Fermentable Fractions of Household Waste (FFOM).

[0093] The pretreatment of biomass from which the first liquid fraction is obtained may be hydrolysis (without enzyme) or pretreatment of the biomass including in particular impregnation of the biomass with an acidic or basic or oxidizing liquor followed by cooking of the impregnated biomass, in particular cooking with steam explosion.

[0094] The first liquid fraction comprising C5 sugars with 5 carbons and C6 sugars with 6 carbons is preferably obtained, according to the invention, after a solid / liquid separation step b) preferably using a biomass pretreated by steam explosion, optionally repulped with a solvent (water in particular) and optionally washed with a solvent (water in particular).

[0095] The invention also relates to the first treated liquid fraction obtained in step d): it thus relates to a liquid comprising a mixture of compounds in aqueous solution, which comprises C5 sugars and conversion products of C6 sugars and possibly other minority compounds present in the juice to be treated by acid or enzymatic hydrolysis, with in addition

[0096] - an S1 content of C5 sugars and / or C6 sugars of between 10 and 100 g / kg of solution

[0097] - including a proportion P1 of C5 sugars and / or C6 sugars in oligomeric form of at most 50% by weight, in particular at most 30% by weight, in particular at most 20 or 10% by weight relative to the monomeric sugars.

[0098] The invention will be described below in more detail, using non-limiting examples and the following figures:

[0099] List of figures

[0100] Figure 1 represents in the form of a block diagram a process for treating lignocellulosic biomass with a view to converting it into alcohol (ethanol), without implementing the treatment by hydrolysis of the sugar juices according to the invention.

[0101] Figure 2 represents in the form of a block diagram a process for treating lignocellulosic biomass with a view to converting it into alcohol (ethanol), which modifies the process of Figure 1 to implement the hydrolysis treatment of sugary juices according to the invention.

[0102] Figure 3 represents in the form of a block diagram a process for treating lignocellulosic biomass with a view to converting it into sugar(s), without implementing the treatment by hydrolysis of the sugar juices according to the invention.

[0103] Figure 4 represents in the form of a block diagram a process for treating lignocellulosic biomass with a view to converting it into sugar(s), which modifies the process of Figure 3 to implement the treatment by hydrolysis of sugary juices according to the invention.

[0104] Figure 5 represents in the form of a block diagram a process for treating lignocellulosic biomass with a view to converting it partly into sugar(s), partly into alcohol (ethanol), without implementing the treatment by hydrolysis of the sugar juices according to the invention.

[0105] Figure 6 represents in the form of a block diagram a process for treating lignocellulosic biomass with a view to converting it partly into sugar(s) and partly into alcohol (ethanol), which modifies the process of Figure 5 to implement the treatment by hydrolysis of the sugary juices according to the invention. Throughout this text, and in particular in the description of the figures, the term reactor does not require that there be only one, and can be understood as a unit comprising at least one reactor or several reactors (mounted in series or in parallel). The same applies to all other devices, in particular tools such as filtration, solid / liquid separation, etc. (for the sake of brevity).

[0106] Please note that throughout this text, “solid” is to be understood in opposition to “liquid”, but that any solid fraction may still contain a certain proportion of liquid (and vice versa). This proportion of solid and soluble compounds in a sample can be assessed by measuring its Dry Matter (acronym “DM”) content, which is measured according to ASTM E1756 - 08(2015) “Standard Test Method for Determination of Total Solids in Biomass”.

[0107] Figures 1 to 6 represent process block diagrams and are highly simplified to facilitate understanding. They do not necessarily represent all the steps / equipment necessary for the processes described, focusing on the most significant steps / equipment / flows in view of the invention.

[0108] The references keep the same meaning from one figure to another.

[0109] Description of the embodiments

[0110] The invention integrates into a process for converting biomass, of the lignocellulosic type, into sugar(s) or alcohol, an acid or enzymatic hydrolysis treatment of sugar juices containing C5 sugars, and, in a lower content / proportion, C6 sugars, so as to reduce or even eliminate the content of sugars in oligomeric form in favor of their monomeric form, in order to benefit from it, in particular either to increase the conversion yield of the biomass (into alcohol more particularly), or to obtain sugars of higher quality / purity, or to reduce production costs.

[0111] Indeed, in the biomass treatment process, the invention focuses on processes with pretreatment of the biomass before enzymatic hydrolysis, pretreatment which results in the production of sweet juices mixing C5 sugars and C6 sugars.

[0112] We will therefore describe:

[0113] - firstly, the acid or enzymatic treatment stage of the sugary juices from stage d) of lignocellulosic biomass conversion,

[0114] - then, in a second step, and using figures 1 to 6, the process for converting lignocellulosic biomass producing these sugary juices and integrating this treatment step d) to benefit from them. Treatment step by hydrolysis of sugary juices in C5 and C6

[0115] This chemical or biochemical treatment involves bringing the juice sweetened with C5 and C6 sugars, juice obtained by treating material based on lignocellulosic biomass and comprising mainly C5 sugar, into contact with a hot acid medium or with enzymes, so that the proportion of oligomeric sugar decreases in favor of the monomeric form of sugars.

[0116] The composition of the sugar juice 6 to be treated may vary depending on the biomass, the type of pretreatment, the pretreatment conditions, the washing conditions of the pretreated biomass.

[0117] For example, the sweet juice to be treated according to the invention may have the following composition:

[0118] - between 0.5 and 30 g of glucose per kg of juice, in particular between 5 and 15 g / kg of glucose

[0119] - between 10 and 100 g of xylose per kg of juice, in particular between 20 and 60 g / kg of xylose

[0120] - between 0.5 and 36 g / kg of potential glucose, in particular between 5.5 and 20 g / kg of potential glucose, or between 0.1 and 35 g / kg of oligomeric glucose, in particular between 0.5 and 30 g / kg of oligomeric glucose, in particular between 0.5 and 10 g / kg of oligomeric glucose

[0121] - between 10 and 130 g / kg of potential xylose, in particular between 22 and 75 g / kg of potential xylose, or between 0.1 and 30 g / kg of oligomeric xylose, in particular between 2 and 20 g / kg of oligomeric xylose with the following conventions:

[0122] - Glucose concentration is understood in the sense of monomeric glucose.

[0123] - The xylose concentration is understood in the sense of monomeric xylose.

[0124] - These concentrations can be analyzed for example by high performance liquid chromatography (HPLC) methods

[0125] - The potential sugar concentration is the measurement of the concentration of monomeric sugars after acid hydrolysis on the initial sugar juice at 120°C for 1 hour in the presence of a large excess of dilute acid: to 0.3 grams of DM of the initial juice are added 4.92 grams of 72% sulfuric acid and water, the quantity of which is calculated to obtain a mixture of 90 g.

[0126] - The concentration of oligomeric sugars corresponds to the difference between the concentration of potential sugars and the concentration of monomeric sugars.

[0127] The invention consists, in its first embodiment, in treating this type of sweet juice hot and under acidic conditions, in order to hydrolyze the sugars in oligomeric form into sugars in monomeric form, while preserving the monomeric sugars already present in the initial sweet juice. Examples of treatment of sweet juice by acid hydrolysis

[0128] Example 1 (comparative)

[0129] We start with an initial sweet juice M from biomass pretreated by acid impregnation of the biomass followed by steam explosion, pretreated biomass which is then washed and separated into liquid fraction (the sweet juice) and solid fraction in accordance with the teaching of the aforementioned patent FR 3 083 126, to which we will refer for more details. This is the juice from stream 6 described below.

[0130] Briefly, this pretreatment is an operation of impregnation of lignocellulosic biomass (wheat straw) with an acid liquor, followed by a steam explosion operation of the impregnated biomass. The pretreated biomass undergoes a liquid / solid separation operation at the end of the pretreatment step, this liquid / solid separation step comprising a contacting step between the pretreated lignocellulosic biomass and water, and a filtration and optionally washing step. To obtain the initial sweet juice M to be treated according to the invention, 550 kg of pretreated biomass are mixed with 1010 kg of water, then filtered and then pressed. After filtration and pressing, 885 kg of a juice M, also called C5 hydrolysate, is obtained. The pretreatment taking place under acidic conditions, this juice has a pH of 1.5.

[0131] The concentration of compounds of interest in this initial sweet juice M is given in Table 1 below, with concentrations expressed in g per kg of juice. Note that it is possible that the composition contains other impurities, which we have not sought to analyze, for example of the salt (mineral) or acid type, 5-HMF and furfural, in (very) low levels. Juice M contains 49.5 g / kg of glucose and xylose sugars. The dry matter content of the initial sweet juice M is 8% by weight. The concentrations of minority sugars, such as arabinose, galactose and mannose for this biomass, are not indicated.

[0132] [Table 1]

[0133] This juice is the control juice, which will be treated according to the invention in the following examples.

[0134] Example 2 (according to the invention)

[0135] We start with the sweet juice M defined in example 1. It is treated according to the invention with the following operating conditions: The juice is treated in a stirred batch reactor for 1 hour at 120°C. The pH of the juice is already acidic (pH of approximately 1.5), no acid is added to the juice.

[0136] Example 3 (according to the invention)

[0137] We start with the sweet juice M defined in example 1. It is treated according to the invention with the following operating conditions: The juice is treated in a stirred batch reactor for 1 hour at 120°C. 72% sulfuric acid in water is added to the initial sweet juice M so that the final concentration of pure sulfuric acid added to the total mixture is 1% by weight.

[0138] Example 4 (according to the invention)

[0139] We start with the sweet juice M defined in example 1. It is treated according to the invention with the following operating conditions: The juice is treated in a stirred batch reactor for 1 hour at 120°C. 72% sulfuric acid in water is added to the initial sweet juice M so that the final concentration of pure sulfuric acid added to the total mixture is 2% by weight.

[0140] Example 5 (comparative)

[0141] We start with the sweet juice M defined in example 1. It is treated according to the invention with the following operating conditions: The juice is treated in a stirred batch reactor for 1 hour at 120°C. 72% sulfuric acid in water is added to the initial sweet juice M so that the final concentration of pure sulfuric acid added to the total mixture is 3% by weight.

[0142] Example 6 (comparative)

[0143] We start with the sweet juice M defined in example 1. It is treated according to the invention with the following operating conditions: The juice is treated in a stirred batch reactor for 1 hour at 120°C. 72% sulfuric acid in water is added to the initial sweet juice M so that the final concentration of pure sulfuric acid added to the total mixture is 4% by weight.

[0144] Table 2 below groups together the sugar concentrations in the sweet juices of the examples once hydrolyzed according to the invention.

[0145] C is the concentration of glucose and xylose sugars analyzed by HPLC in g / kg, and R is the change in the yield of monomeric sugars.

[0146] [Table 2]

[0147]

[0148] The first line tO corresponds to the concentrations of juice M before starting the treatment according to the invention. Note that the sugar concentration decreases when acid is added, due to the dilution caused by this addition of acid in aqueous solution: the more acid is added, the more the concentration decreases.

[0149] The theoretical potential sugar concentration at tO + 1 hour corresponds to the total potential glucose and xylose of the juice M: it is the sugar concentration after acid hydrolysis in the presence of excess acid under dilute conditions. Thus the maximum change in the yield of monomeric sugars is 15.5%.

[0150] From the data in Table 2, we see that without adding acid (example 2), since the juice is already at an acidic pH, a certain amount of oligomers is converted into monomers by the heat treatment. By adding 1% (example 3) and 2% acid (example 4), this is also the case, with an increased yield.

[0151] On the other hand, by adding 3% (example 5) or 4% of acid (example 6), there is no longer a favorable change in yield: the conversion of oligomers into monomers is thwarted by the degradation of the monomers.

[0152] In conclusion, we see that the acid hydrolysis of juices according to the invention is favorable for obtaining juices with higher monomeric sugar contents and a lower oligomeric sugar content. However, the treatment must be adjusted, particularly in terms of acidity, because too high an acidity (and / or too high a treatment temperature) can lead to degradation of the monomeric sugars, which can tend to lose all or part of the benefit of the invention. Examples of treatment of sweet juice by enzymatic hydrolysis

[0153] The invention consists, in its second embodiment, in treating this type of sweet juice by enzymatic hydrolysis, in order to hydrolyze the sugars in oligomeric form into sugars in monomeric form, while preserving the monomeric sugars already present in the initial sweet juice.

[0154] Example 7 (comparative)

[0155] We start with an initial sweet juice M from biomass pretreated by acid impregnation of the biomass followed by steam explosion, pretreated biomass which is then washed and separated into liquid fraction (the sweet juice) and solid fraction in accordance with the teaching of the aforementioned patent FR 3 083 126, to which we will refer for more details. This is the juice from stream 6 described below.

[0156] Briefly, this pretreatment is an operation of impregnation of lignocellulosic biomass (here wheat straw) with an acid liquor, followed by a steam explosion operation of the impregnated biomass. The pretreated biomass undergoes a liquid / solid separation operation at the end of the pretreatment step, this liquid / solid separation step comprising a contacting step between the pretreated lignocellulosic biomass and water, and a filtration and optionally washing step. To obtain the initial sweet juice M to be treated according to the invention, 550 kg of pretreated biomass are mixed with 1010 kg of water, then filtered and then pressed. After filtration and pressing, 885 kg of a juice M, also called C5 hydrolysate, is obtained. The pretreatment taking place under acidic conditions, this juice has a pH of 1.7.

[0157] The concentration of compounds of interest in this initial sweet juice M is given in Table 3 below, with concentrations expressed in g per kg of juice. Note that it is possible that the composition contains other impurities, which we have not sought to analyze, for example of the salt (mineral) or acid type, 5-HMF and furfural, in (very) low levels. The dry matter content in the initial sweet juice is 6.9% by weight. Juice M contains 38.4 g / kg of sugars glucose and xylose.

[0158] The concentrations of minority sugars, such as arabinose, galactose and mannose for this biomass, are not indicated.

[0159] [Table 3]

[0160] This juice is the control juice, which will be treated according to the invention in the following examples.

[0161] Example 8 (according to the invention)

[0162] We start from the initial sweet juice M defined in example 7. We treat it according to the invention with the following operating conditions:

[0163] The initial juice M is at pH 1.7. It feeds a stirred reactor, the reaction is carried out in batch. A sufficient quantity of aqueous KOH solution is added to increase the pH of the juice to a pH of approximately 4.8.

[0164] The juice is then treated by adding 0.1 g protein / kg of juice by adding an enzyme cocktail produced by Trichoderma reeseiet having a protein concentration of 35.8 g / kg (measured by the Kjeldhal method), FPase activity (of 0.8 IU / mg), beta-glucosidase activity (of 35.6 lU / mg) and xylanase activity, then stirring the mixture for 24 hours at 50°C.

[0165] Table 4 below groups together the sugar concentrations of the examples once hydrolyzed according to the invention, at t=0 (sugar contents at the start of treatment) and at t = t0 + 1 hour.

[0166] C is the concentration of glucose and xylose sugars analyzed by HPLC in g / kg, and R is the change in the yield of monomeric sugars. The maximum change in sugar yield is 23%.

[0167] [Table 4]

[0168] The data in Table 4 show that, after 1 hour of treatment, there is a significant conversion of oligomeric sugars into monomeric sugars, since that the yield of monomeric sugars is increased by 12%, or more than 50% of the theoretical possible increase (which is 23%).

[0169] After 1 hour of reaction, the concentrations of glucose and xylose sugars have reached a plateau; it is not necessary to continue the treatment for long periods, because the less significant improvement in the yield of monomeric sugars risks being less advantageous in view of an extension of the reactor immobilization time, for example.

[0170] In conclusion, we see that the enzymatic hydrolysis of juices according to the invention is favorable for obtaining juices with higher monomeric sugar contents and a lower oligomeric sugar content. The invention is flexible in terms of implementation, it can be operated at low temperature, the nature and quantity of enzymes added during the treatment can be adjusted, in particular according to the type of sweetened juice. And a significant increase in the monomeric sugar content is obtained with reasonable treatment times. If necessary, in particular if a very high purity of monomeric sugar is required, the treatment time can be extended or the parameters mentioned above can be adjusted.

[0171] Processes for converting lignocellulosic biomass producing sugary juices and integrating the step of treating said sugary juices previously described

[0172] Three conversion processes are described below:

[0173] - a process A for conversion into alcohol (ethanol)

[0174] - a process B of conversion into sugar(s), and

[0175] - a so-called “hybrid” process C aimed at obtaining both an alcohol and sugar(s)

[0176] Process A for converting biomass into ethanol

[0177] It is illustrated using figures 1 and 2.

[0178] Figure 1 depicts a conversion process without the processing step d) described above. The figure references represent the following flows / devices / steps:

[0179] 1: Biomass

[0180] 2: Conditioning and pretreatment

[0181] 3: Pretreated biomass

[0182] 3a: Pretreated biomass towards the filtration tool

[0183] 3b: Pretreated biomass towards enzymatic hydrolysis (optional stream)

[0184] 4: Solid / liquid separation (a belt filter or a filter press for example) to extract a sweet juice, with an optional washing step

[0185] 5: Water as contact and / or washing fluid

[0186] 6: Sweet juice containing mostly C5 sugars 6a: Sweet juice containing mostly C5 sugars towards enzyme production 6b: Sweet juice containing mostly C5 sugars towards yeast propagation

[0187] 7: Pretreated and washed biomass

[0188] 8: Enzyme production reactor

[0189] 9: Mushroom inoculum (Trichoderma Reese / for example) for enzyme production

[0190] 10: Enzyme cocktail (mixture of one or more enzymes, including cellulases, beta glucosidases, xylanases, etc.)

[0191] 11: Yeast propagation reactor

[0192] 12: Yeasts

[0193] 13: Propagated yeasts

[0194] 14: Enzymatic hydrolysis reactor.

[0195] 15: Hydrolyzate

[0196] 16: Fermentation reactor

[0197] 17: Fermentation must (wine)

[0198] 18: Solid / liquid separation (e.g. a filter press) with an optional step of washing the solid residue with a solvent (e.g. water)

[0199] 19: Solid residue (composed mainly of lignin)

[0200] 20: Liquid product of filtration, here filtered wine

[0201] 21: Separation of ethanol and water (distillation column, sieve for example)

[0202] 22: Liquid residue (vinasses)

[0203] 23: Purified ethanol

[0204] If we take the process sequence according to Figure 1: Biomass 1 undergoes conditioning / pretreatment in unit 2 (possible mechanical grinding, dust removal, removal of any metal parts, then, here as an example, impregnation with an acid liquor and cooking / steam explosion of the pretreated biomass 3). Part of this pretreated biomass, flow 3a, goes to a solid / liquid filtration tool 4, said tool also being supplied with water 5 as contact and / or washing water. Initially, the pretreated biomass is contacted with water to improve its filterability. The mixture is then filtered on a belt filter, and washed with water. Another part of the pretreated biomass, stream 3b, can go to the enzymatic hydrolysis reactor 14. This reactor 14 is also fed by stream 7 which is the solid fraction resulting from filtration in unit 4, which is therefore the solid washed pretreated biomass.

[0205] At the outlet of reactor 14, there is a flow 15 of hydrolyzate (sugars), which then feeds a fermentation reactor 16 to be converted into ethanol: at the outlet of fermentation reactor 16, a fermentation must is obtained, also called wine, which contains ethanol in water. A solid / liquid separation tool 18 separates a ligneous solid residue 19 from a liquid fraction 20, the filtered wine. This filtered wine is conducted into a separation tool 21 (distillation column) to obtain ethanol 23 and an aqueous liquid residue (called vinasse).

[0206] At the outlet of the separation tool 4, the liquid fraction 6 is an aqueous sugary juice comprising mainly C5 sugars. All or part of this fraction, the flow 6a, can go to the enzyme production reactor 8, which produces an enzymatic cocktail 10 to feed the enzymatic hydrolysis reactor 14: this flow can thus constitute a growth and / or production substrate for microorganisms of the Trichoderma reesei type which produce this mixture of enzymes 10. All or part of this flow 6, the flow 6b, can also go to the reactor 11 for propagation of the yeasts 13 which feed the fermentation reactor 16. Here again, the sugary juice 6b will be able to serve as a propagation substrate for yeasts, for example Saccharomyces, in particular the species Saccharomyces cerevisae.

[0207] It should also be noted that the enzymatic hydrolysis operation 14 is preferably carried out in 2 stages: liquefaction with a fed-batch of substrate then enzymatic hydrolysis in batch, (possibly with two reactors in series, or in the same reactor), to work at the highest possible DM content and to convert lignocellulosic substrates whose rheology can be complex. Neutralization of the medium can be carried out before the enzymatic hydrolysis, for example by adding a basic solution in the case where the pretreatment is carried out under acidic conditions.

[0208] It should also be noted that enzymatic hydrolysis and fermentation can be done simultaneously (SSCF). When they are done one after the other, an adjustment of the pH of the medium between units 14 and 16 can be achieved.

[0209] It should also be noted that enzyme production and / or yeast propagation can be done on the biomass processing site, as shown in Figure 1. But one or the other can also be done ex situ: ready-to-use enzymes or yeasts can thus be brought to the site. This explains why, depending on the choices made on this subject, the flow can be divided into two flows 6a, 6b (with a distribution between the two flows which can be equal or not according to the needs), or be used only for yeast propagation or only for enzyme production.

[0210] Figure 2 shows the method of Figure 1, but with the modifications according to the invention, and the following additional references:

[0211] 6a': Sweet juice comprising C5 and C6 sugars with high monomeric sugar content towards enzyme production

[0212] 6b': Sweet juice comprising C5 and C6 sugars with high monomeric sugar content towards yeast propagation

[0213] 6c': Sweet juice comprising C5 and C6 sugars with high monomeric sugar content towards fermentation

[0214] 24: Acid or enzymatic hydrolysis treatment reactor

[0215] 25: Addition of acid (acid hydrolysis) or addition of enzymes and KOH

[0216] 26: Sweet juice comprising C5 and C6 sugars with high monomeric sugar content and possibly enzymes in the case of enzymatic hydrolysis

[0217] 27: Possible solid / liquid separation or by size difference (a centrifuge, a filter or an ultrafiltration unit for example) of the enzymes contained in the juice 26

[0218] 28: In the case of enzymatic hydrolysis of the sugar juice, at least partial recycling of the enzymes

[0219] 29: Sweet juice identical to juice 26 or without enzymes if choice of enzymatic hydrolysis with separation of sugars / enzymes in unit 27

[0220] Note that the pretreated biomass flow 3 is divided in Figure 2 into two flows: flow 3a which goes to tool 4 and flow 3b which goes directly to the enzymatic hydrolysis reactor 14. But here, as in the case of the processes represented in the following figures, the relative proportion between flows 3a and 3b is variable.

[0221] And according to an embodiment of the invention, it is also provided that the entire pretreated biomass flow 3 first passes into the tool 4 before separation and sending of the solid portion to the hydrolysis reactor 14: there is only one flow 3 / 3a entering the tool 4 in its entirety, and the flow 3b is zero: the reactor 14 is no longer supplied with flow 3b. This embodiment is more particularly recommended in the case of the production of sugar A, more than in the case of the production of alcohol B or sugar and alcohol C.

[0222] This zero 3b flow scenario is therefore also part of the invention, whether it is a process for producing alcohol, sugar or a hybrid alcohol / sugar process.

[0223] Stream 26 or 29 of sugary juice can be used as a substrate for enzyme production, yeast propagation or in fermentation.

[0224] Here, the stream 6 containing more C5 sugars than C6 sugars is treated as follows: it is brought into a chemical (acid) or biochemical (enzyme) hydrolysis reactor 24, which may include a preliminary step of increasing / adjusting the pH of the juice 6, for example with a basic solution of sodium or potassium hydroxide, in the case where the pretreatment of the biomass was carried out in acidic conditions. The reactor 24 is therefore supplied with acid (acid hydrolysis) or with enzymes, possibly with the simultaneous or prior addition of a base (enzymatic hydrolysis). At the outlet of the reactor 24, there is a stream 26 of sugary juice depleted in oligomeric sugars.

[0225] The optional separation tool 27 makes it possible to recover a solid fraction 28 of enzymes (in the case where the enzymes are, for example, supported on a solid support) or a fraction of the enzymes soluble in the juice which would be, for example, separated by size difference between the proteins and the sugars. These enzymes will be able, in whole or in part, to be recycled in the reactor 24.

[0226] The separated liquid fraction 29 is therefore a sweet juice either identical to juice 26 in the case of acid hydrolysis, or partially or totally devoid of enzymes in the case of enzymatic hydrolysis. Note however that, even in the case of enzymatic hydrolysis, the separation of enzymes remains optional, especially when this juice is not used as is.

[0227] Process B for converting biomass into sugars

[0228] It is illustrated by Figures 3 and 4.

[0229] Figure 3 represents the process without the sugar juice treatment according to the invention. This involves stopping the conversion of the biomass at the sugar production stage, therefore without fermentation. Compared to Figure 1, the sugar juice 20, mainly consisting of C6 sugars, is therefore the first final product which is recovered, the stream 6a can be used to serve as a substrate for the growth and / or production of enzymes in the reactor 8 (if in situ enzyme production), and the stream 6b is the second final product which can be recovered, a sugar juice mainly in C5, but which still contains C6 sugars.

[0230] Figure 4 is a process which integrates the treatment of sugar juice according to the invention into the process of Figure 3: It shows the reactors / tools 24, 27 of the process of Figure 2, which are operated in the same way. Here, the sugar juice 6 containing mainly C5 / C6 sugars is treated into a juice 26 (or 29), which is divided partly into a stream 6a' of C5 sugars to serve as a substrate for the growth / production of enzymes in the reactor 8 if the production of enzymes is done in situ, and partly or entirely into a stream 6d', which is a C5 / C5 sugar juice with a high content of monomeric sugars which can be used as such.

[0231] “Hybrid” process C for converting biomass into ethanol and sugar(s)

[0232] It is illustrated by Figures 5 and 6.

[0233] The process according to Figure 5 does not use the sugar juice treatment according to the invention. Here, the aim is to produce sugars and ethanol in parallel. Compared to the process in Figure 1, which aims to produce ethanol, here we have both:

[0234] - ethanol production, which is flow 23 obtained as in the process of figure 1, and - sugar production mainly in C5: this is flow 6d, from flow 6 as in the process of figure 3. This flow 6d can be a part of flow 6, or the whole of this flow (if ex situ production of enzymes, and / or ex situ propagation of yeasts, or if we prefer to use other, external sources, for the growth / propagation of microorganisms / production of enzymes).

[0235] The process of Figure 6 integrates, in the process of Figure 5, the treatment of sugary juice according to the invention: We find the reactors / tools 24, 27 previously described, the obtaining of a treated flow 26 or 29 in sugars with high monomeric content, and that of a flow 6d' which constitutes all or part of the juice 26, 29 and which constitutes a sugary juice rich in monomeric sugar which can be used as is, in parallel with the production of ethanol 23.

[0236] From these different implementations of the invention, we see all the advantages: The hydrolyzate of lignocellulosic sugars composed of a mixture of sugars with 6 and 5 carbon atoms is purified into a hydrolyzate containing C5 / C6 sugars with a high monomeric sugar content / low oligomeric sugar content:

[0237] The use of this treated mixture of C5 / C6 sugars is beneficial for many chemical conversion applications (conversion of xylose to xylitol by catalysis) or biochemical applications (yeast propagation, induction of fungi for the production of enzymes for example).

[0238] Note that the treatment of sugary juice by enzymatic hydrolysis is carried out on a clear medium, it is easy to separate the enzymes by sieving separation, by size difference between the components to be separated and that of the pores of the membrane, for example ultrafiltration membranes, to remove and recycle the microorganisms.

[0239] The sugar juice treated according to the invention can be concentrated, if necessary, to a content of, for example, 50 g / kg, which is all the more advantageous since this sugar juice is used for the production of enzymes and propagation of yeasts. The juice treatment step is therefore perfectly integrated into the production of ethanol and / or 2G sugars.

[0240] Examples implementing a biomass conversion process

[0241] Example 9: Sugar production process (comparative):

[0242] A lignocellulosic biomass 1 containing 24% by weight of xylan and 33% by weight of cellulose and whose dry matter content is 88% by weight undergoes a pretreatment 2 which consists of:

[0243] - impregnation with an aqueous solution of sulfuric acid: the impregnation is carried out in the presence of acid liquor heated to 80°C. The acid concentration in the liquor is 2.5% by weight (expressed as % by weight of H2SC>4). - the introduction of this impregnated biomass into a pressurized reactor heated to 185°C with steam injection, for a residence time of 5 min.

[0244] - an atmospheric pressure expansion releasing steam and pre-treated biomass with a dry matter content of 44% by weight.

[0245] The conversions are shown in Table 5 below:

[0246] [Table 5]

[0247] The pretreated biomass 3 is then brought into contact with water 5 and feeds a belt filter 4 to carry out a solid / liquid separation allowing the obtaining of the sugary juice 6 and a pretreated and washed biomass 7.

[0248] The sugar content in the sweet juice 6 is determined by HPLC (high performance liquid chromatography), and makes it possible to determine a sugar extraction yield defined as the ratio between the quantity of sugars extracted in the juice 6 and the quantity of sugars present in the pretreated biomass 3. This yield is 77%.

[0249] The concentration of compounds of interest in this sweet juice is given in Table 6 below, with concentrations expressed in g per kg of juice. Note that it is possible that the juice contains other impurities, which we have not sought to analyze, for example of the salt (mineral) or acid type, in (very) low levels. The dry matter content in the sweet juice is 6.9% by weight. The juice contains 43.0 g / kg of sugars glucose and xylose.

[0250] The concentrations of minority sugars, such as arabinose, galactose and mannose for this biomass, are not indicated.

[0251] [Table 6]

[0252] The yield of C5 and C6 monomeric sugars in the juice relative to the potential C5 and C6 sugars present in the biomass is 17.4%. The yield of C5 monomeric sugars relative to the potential C5 sugars present in the lignocellulosic biomass is 33.8% by weight, and the yield of C6 monomeric sugars relative to the potential C6 sugars present in the lignocellulosic biomass is 6.7% by weight.

[0253] The pretreated and washed biomass 7 feeds an enzymatic hydrolysis reactor 14. The hydrolysis is carried out under the following operating conditions: 50°C, pH 4.8. The dry matter content is 16.8% by weight, or 7.5% by weight of cellulose. The quantity of enzymes added is 21.7 mg protein / g cellulose. The enzyme cocktail used was produced by Trichoderma reesei and has FPase and beta-glucosidase activity. Under the conditions used, the conversion yield of cellulose to glucose is 83% by weight.

[0254] The hydrolyzate obtained 15 is then filtered on a filter press to remove a solid residue 19 and obtain a sweet juice 20.

[0255] The sugar content in the sweet juice 20 is determined by HPLC (high performance liquid chromatography), and makes it possible to determine a sugar extraction yield defined as the ratio between the quantity of sugars extracted in the juice 20 and the quantity of sugars present in the hydrolyzate 15: this yield is 74%.

[0256] The dry matter content of solid residue 19 is 33.5% by weight.

[0257] The concentration of compounds of interest in the sweet juice 20 is given in Table 7 below, with concentrations expressed in g per kg of juice. Note that it is possible that the juice contains other impurities, which we did not seek to analyze, for example of the salt (mineral) or acid type, in (very) low contents. The dry matter content in the sweet juice is 9.3% by weight. The concentrations of minority sugars, such as arabinose, galactose and mannose for this biomass, are not indicated. [Table 7]

[0258] The yield of monomeric sugars in the juice compared to the potential sugars present in the biomass is 36.4%.

[0259] Thus, by combining the two sugar juices obtained, juice 6 and juice 20, the yield of monomeric sugars relative to the potential sugars present in the biomass is 53.8% by weight. The yield of C5 monomeric sugars relative to the potential C5 sugars present in the lignocellulosic biomass is 41.9% by weight, and the yield of C6 monomeric sugars relative to the potential C6 sugars present in the lignocellulosic biomass is 61.5% by weight.

[0260] Example 10: Process for producing sugars - According to the invention

[0261] A lignocellulosic biomass 1 containing 24% by weight of xylan and 33% by weight of cellulose and whose dry matter content is 88% by weight undergoes a pretreatment 2 which consists of:

[0262] - impregnation with an aqueous solution of sulfuric acid: the impregnation is carried out in the presence of acid liquor heated to 80°C. The acid concentration in the liquor is 2.5% by weight (expressed as % by weight of H2SC>4).

[0263] - the introduction of this impregnated biomass into a pressurized reactor heated to 185°C with steam injection, for a residence time of 5 min.

[0264] - an atmospheric pressure expansion releasing steam and pre-treated biomass with a dry matter content of 44% by weight.

[0265] The conversions are shown in Table 8 below: [Table 8]

[0266] The pretreated biomass 3 is then brought into contact with water 5 and feeds a belt filter 4 to carry out a solid / liquid separation allowing the obtaining of the sugary juice 6 and a pretreated and washed biomass 7.

[0267] The sugar content in the sweet juice 6 is determined by HPLC (high performance liquid chromatography), and makes it possible to determine a sugar extraction yield defined as the ratio between the quantity of sugars extracted in the juice 6 and the quantity of sugars present in the pretreated biomass 3. This yield is 77%.

[0268] The concentration of compounds of interest in this sweet juice is given in Table 9 below, with concentrations expressed in g per kg of juice. Note that it is possible that the juice contains other impurities, which we did not seek to analyze, for example of the salt (mineral) or acid type, in (very) low levels. The dry matter content in the initial sweet juice is 6.9% by weight. The juice contains 43.0 g / kg of glucose and xylose sugars. The concentrations of minority sugars, such as arabinose, galactose and mannose for this biomass, are not indicated.

[0269] [Table 9]

[0270] The sweet juice 6 is treated in a reactor 24 stirred in batch, for 1 hour at 120°C in the presence of H2SC>4. 1% by weight of pure H2SC>4 is added to the sweet juice 6.

[0271] The concentration of compounds of interest in the sweet juice after treatment by acid hydrolysis is given in Table 10 below, with concentrations expressed in g per kg of juice. Note that it is possible that the juice contains other impurities, which we have not sought to analyze, for example of the salt (mineral) or acid type, in (very) low levels.

[0272] [Table 10]

[0273] The sweet juice 26 obtained according to the process of the invention therefore has a reduced oligomeric sugar content of 35% compared to the sweet juice 6. The yield of monomeric sugars C5 and C6 in the juice compared to the potential sugars present in the lignocellulosic biomass 1 is 18.2% by weight. The increase in the yield of glucose and xylose in the juice 26 is respectively 9% by weight and 4% by weight.

[0274] The pretreated and washed biomass 7 feeds an enzymatic hydrolysis reactor 14. The hydrolysis is carried out under the following operating conditions: 50°C, pH 4.8. The dry matter content is 16.8% by weight, or 7.5% by weight of cellulose. The quantity of enzymes added is 21.7 mg protein / g cellulose. The enzymatic cocktail used was produced by Trichoderma reesei and has FPase and beta-glucosidase activity. Under the conditions used, the conversion yield of cellulose into glucose is 83% by weight. The hydrolyzate obtained 15 is then filtered on a filter press to remove a solid residue 19 and obtain a sweet juice 20.

[0275] The sugar content in the sweet juice 20 is determined by HPLC (high performance liquid chromatography), and makes it possible to determine a sugar extraction yield defined as the ratio between the quantity of sugars extracted in the juice 20 and the quantity of sugars present in the hydrolyzate 15: this yield is 74%.

[0276] The dry matter content of solid residue 19 is 33.5% by weight.

[0277] The concentration of compounds of interest in the sweet juice 20 is given in Table 11 below, with concentrations expressed in g per kg of juice. Note that it is possible that the juice contains other impurities, which we have not sought to analyze, for example of the salt (mineral) or acid type, in (very) low contents. The dry matter content in the sweet juice is 9.3% by weight. The concentrations of minority sugars, such as arabinose, galactose and mannose for this biomass, are not indicated.

[0278] [Table 11]

[0279] The yield of monomeric sugars in the juice compared to the potential sugars present in the biomass is 36.4%.

[0280] Thus, by combining the two sugar juices obtained, juice 26 and juice 20, the yield of monomeric sugars compared to the potential sugars present in the biomass is 55% by weight, therefore an improved yield. The yield of C5 monomeric sugars compared to the potential C5 sugars present in the lignocellulosic biomass is 43.1% by weight, and the yield of C6 monomeric sugars compared to the potential C6 sugars present in the lignocellulosic biomass is 62.1% by weight.

[0281] Example 11: Process for producing sugars - according to the invention A lignocellulosic biomass 1 containing 24% by weight of xylan and 33% by weight of cellulose and whose dry matter content is 88% by weight undergoes a pretreatment 2 which consists of:

[0282] - impregnation with an aqueous solution of sulfuric acid: the impregnation is carried out in the presence of acid liquor heated to 80°C. The acid concentration in the liquor is 2.5% by weight (expressed as % by weight of H2SC>4).

[0283] - the introduction of this impregnated biomass into a pressurized reactor heated to 150°C with steam injection, for a residence time of 7 min.

[0284] - an atmospheric pressure expansion releasing steam and pre-treated biomass with a dry matter content of 45% by weight.

[0285] The conversions are shown in Table 12 below:

[0286] [Table 12]

[0287] The pretreated biomass 3 is then brought into contact with water 5 and feeds a belt filter 4 to carry out a solid / liquid separation allowing the production of the sugary juice 6 and a pretreated and washed biomass 7.

[0288] The sugar content in the sweet juice 6 is determined by HPLC (high performance liquid chromatography), and makes it possible to determine a sugar extraction yield defined as the ratio between the quantity of sugars extracted in the juice 6 and the quantity of sugars present in the pretreated biomass 3. This yield is 77%.

[0289] The concentration of compounds of interest in this sweet juice is given in Table 13 below, with concentrations expressed in g per kg of juice. Note that it is possible that the juice contains other impurities, which we have not sought to analyze, for example of the salt (mineral) or acid type, in (very) low levels. The dry matter content in the initial sweet juice is 8.0% by weight. The juice contains 37.3 g / kg of sugars glucose and xylose.

[0290] The concentrations of minority sugars, such as arabinose, galactose and mannose for this biomass, are not indicated.

[0291] [Table 13]

[0292] The yield of C5 and C6 monomeric sugars in the juice compared to the potential sugars present in the lignocellulosic biomass is 15%.

[0293] The operating conditions implemented in pretreatment step 2, in particular the residence time, the temperature and the acid concentration in the liquor, make it possible to have a yield of C5 monomeric sugars relative to the potential C5 sugars present in the biomass of 33.8% by weight, i.e. a yield equivalent to that of example 9, but with less severe pretreatment conditions: .

[0294] Indeed, the temperature of the pretreatment step is here 150°C and not 185°C, and yet the same yield of sugars 5 is obtained in juice 6, with an additional gain in yield thanks to the hydrolysis step according to the invention which makes it possible to have a juice 26 depleted in oligomers and rich in C5 monomers.

[0295] The sweet juice 6 is treated in a stirred reactor in batch 24, for 1 hour at 120°C in the presence of H2SC>4 at 1% by weight of pure H2SC>4 is added to the sweet juice 6.

[0296] The concentration of compounds of interest in the sweet juice after treatment by acid hydrolysis is given in Table 14 below, with concentrations expressed in g per kg of juice. Note that it is possible that the juice contains other impurities, which we have not sought to analyze, for example of the salt (mineral) or acid type, in (very) low levels.

[0297] [Table 14]

[0298] The sweet juice 26 obtained according to the process of the invention therefore has a reduced oligomeric sugar content of 35% compared to the sweet juice 6. The yield of monomeric sugars in the juice compared to the potential sugars present in the biomass is 18.1% by weight. The increase in the yield of glucose and xylose in the juice 26 is respectively 45% by weight and 18% by weight.

[0299] The pretreated and washed biomass 7 feeds an enzymatic hydrolysis reactor 14. The hydrolysis is carried out under the following operating conditions: 50°C, pH 4.8. The dry matter content is 16.6% by weight, or 7.5% by weight of cellulose. The quantity of enzymes added is 21.7 mg protein / g cellulose. The enzyme cocktail used was produced by Trichoderma reesei and has FPase and beta-glucosidase activity. Under the conditions used, the conversion yield of cellulose to glucose is 83% by weight.

[0300] The hydrolyzate obtained 15 is then filtered on a filter press to remove a solid residue 19 and obtain a sweet juice 20.

[0301] The sugar content in the sweet juice 20 is determined by HPLC (high performance liquid chromatography), and makes it possible to determine a sugar extraction yield defined as the ratio between the quantity of sugars extracted in the juice 20 and the quantity of sugars present in the hydrolyzate 15: this yield is 74%.

[0302] The dry matter content of solid residue 19 is 33.5% by weight.

[0303] The concentration of compounds of interest in the sweet juice 20 is given in Table 15 below, with concentrations expressed in g per kg of juice. Note that it is possible that the juice contains other impurities, which we have not sought to analyze, for example of the salt (mineral) or acid type, in (very) low contents. The dry matter content in the sweet juice is 9.4% by weight. The concentrations of minority sugars, such as arabinose, galactose and mannose for this biomass, are not indicated.

[0304] [Table 15]

[0305] The yield of monomeric sugars in the juice compared to the potential sugars present in the biomass is 38.4%.

[0306] Thus, by combining the two sugar juices obtained, juice 26 and juice 20, the yield of monomeric sugars relative to the potential sugars present in the lignocellulosic biomass 1 is 57% by weight. The yield of C5 monomeric sugars relative to the potential C5 sugars present in the lignocellulosic biomass is 50.9% by weight, and the yield of C6 monomeric sugars relative to the potential C6 sugars present in the lignocellulosic biomass is 60.2% by weight. The process according to the invention therefore makes it possible to achieve high yields of monomeric sugars, while reducing the temperature at the pretreatment stage, which is very advantageous from the point of view of the energy consumption of the process (reduction of steam consumption).

Claims

Claims 1. Method for treating a lignocellulosic biomass, said method comprising - a) a pretreatment step (2) of the biomass, comprising cooking the biomass, possibly accompanied by a steam explosion, to obtain a pretreated biomass (3) - b) a first step of solid / liquid separation of all or part (3a) of the pretreated biomass (3) obtained in step a) into a first solid fraction (7) of pretreated biomass and a first liquid fraction (6) comprising a mixture of compounds, in particular in aqueous phase, comprising C5 sugars with 5 carbons and C6 sugars with 6 carbons, said C5 sugars and / or said C6 sugars being partly in monomeric form and partly in oligomeric form - c) a first step of enzymatic hydrolysis (14) of the first solid fraction (7) of pretreated biomass obtained in step b), to obtain a hydrolysate (15) in the form of sugar(s), including C6 sugars with 6 carbons, - d) a step of treatment (24) of said first liquid fraction (6) obtained in step b) by hydrolysis under acidic conditions and / or by a second enzymatic hydrolysis, in order to obtain a first treated liquid fraction (26) which is enriched in C5 sugars in monomeric form and / or in C6 sugars in monomeric form and depleted in C5 sugars in oligomeric form and / or in C6 sugars in oligomeric form.

2. Method according to the preceding claim, characterized in that the treatment step d) is a hydrolysis step under acidic conditions carried out at a temperature of at least 60°C, in particular at least 70°C, in particular at least 75°C, or at least 80°C, or at least 90°C, or at least 100°C, and preferably at most 140°C, in particular at most 130°C.

3. Method according to one of the preceding claims, characterized in that the treatment step d) is a hydrolysis step under acidic conditions carried out with at least 0.1% by weight of acid added to said first liquid fraction (6), in particular between 0.2 and 2.8% by weight of acid in said mixture, and / or with a pH of at most 4.5, and preferably between 0.5 and 2.

5.

4. Method according to claim 1, characterized in that the treatment step d) is a second enzymatic hydrolysis step carried out at a temperature of at most 80°C or at most 70°C, in particular at least 20°C, and is preferably between 40 and 60°C.

5. Method according to one of the preceding claims, characterized in that the treatment step d) is an enzymatic hydrolysis step carried out at a pH of at least 3, in particular at least 3.5, in particular at least 4, and preferably at most 6.

6. Method according to one of the preceding claims, characterized in that the treatment step d) is an enzymatic hydrolysis step, and in that it comprises a sub-step d1) of separation of the enzymes from the first treated liquid fraction (26), in order to obtain on the one hand a first treated and separated liquid fraction (29), and on the other hand an enzyme fraction (28) which is at least partly recycled to step d).

7. Method according to one of the preceding claims, characterized in that only a first part (3a) of the pretreated biomass (3) obtained in step a) is conducted to the first step b) of solid / liquid separation, and in that a second part (3b) of the pretreated biomass (3) is conducted directly to step c) of enzymatic hydrolysis.

8. Method according to one of the preceding claims, characterized in that it also comprises a step e) of fermentation (16) by second microorganisms of the hydrolyzate in the form of sugar(s) obtained in step c), in order to obtain a fermented biomass (17) comprising at least one alcohol, in particular ethanol.

9. Method according to one of the preceding claims, characterized in that it comprises a step f) of producing enzymes (8) from first microorganisms, in particular fungi, in order to use said enzymes to ensure the enzymatic hydrolysis of step c), and in that all or part of the first treated liquid fraction (26) obtained in step d) is sent as a substrate for the growth of said first microorganisms and / or for the production of enzymes by said first microorganisms.

10. Method according to claim 8, characterized in that it comprises a step i) of propagation (11) of second fermentation microorganisms, in order to use said microorganisms, in particular yeasts, to ensure the fermentation of step e), and in that all or part of the first treated liquid fraction (26) obtained in step d) is sent to said step i) as a substrate for propagation of said third microorganisms.

11. Method according to claim 8, characterized in that all or part of the first treated liquid fraction (26) obtained in step d) is sent to the fermentation step e) (16).

12. Method according to one of claims 8 or 10 or 11, characterized in that the first microorganisms used in step f) and optionally the second microorganisms organisms used in steps i) and e) are chosen from yeasts, bacteria, fungi, and preferably from yeasts in the genus Saccharomyces, in particular the species Saccharomyces cerevisae or, among bacteria, in the genus Corynebacterium.

13. Method according to one of the preceding claims, characterized in that the pretreatment (2) according to step a) of the biomass comprises - a1) a sub-step of impregnation of the biomass (1) with a liquor, in particular acid, to obtain an impregnated biomass - a2) a sub-step of cooking the impregnated biomass, possibly accompanied by a steam explosion, to obtain a pre-treated biomass (3).

14. Method according to claim 8, 10 or 11, characterized in that it also comprises: - a step j) of separation, in particular by distillation (21), of the fermented biomass in the form of alcohol (20) obtained in step e), with a possible step k) of solid / liquid separation of the fermented biomass before or after said separation step j).

15. Installation for processing a lignocellulosic biomass, said installation comprising - a) a biomass pretreatment unit (2), comprising a biomass cooking device, possibly accompanied by a steam explosion, to obtain a pretreated biomass - b) a first solid / liquid separation unit (4), comprising in particular a filtration device, of all or part (3a) of the pretreated biomass (3) obtained in unit a) into a first solid fraction (7) of pretreated biomass and a first liquid fraction (6) comprising a mixture of compounds, in particular in aqueous phase, comprising C5 sugars with 5 carbons and C6 sugars with 6 carbons, said C5 sugars and / or said C6 sugars being partly in monomeric form and partly in oligomeric form - c) an enzymatic hydrolysis unit (14) of the first solid fraction (7) of pretreated biomass obtained in step b), to obtain a hydrolysate (15) in the form of sugar(s), including C6 sugars with 6 carbons, - a treatment unit (24) of said first liquid fraction (6) obtained in step b) by hydrolysis under acidic conditions and / or by enzymatic hydrolysis, in order to obtain a first treated liquid fraction (26) which is enriched in C5 sugars in monomeric form and / or in C6 sugars in monomeric form and depleted in C5 sugars in oligomeric form and / or in C6 sugars in oligomeric form.

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