RU2793789C2 - Process for production of sugars from biomass derived from guayule plants - Google Patents

Abstract

FIELD: biotechnology.

SUBSTANCE: invention proposes a process for production of sugars from biomass derived from guayule plants, which includes bringing the biomass into contact with water and at least one organic acid and optionally at least one inorganic acid to obtain a mixture of sugars.

EFFECT: invention allows to obtain sugars that can be used as carbon sources in fermentation processes for the production of alcohols, lipids, diols or in chemical synthesis processes for the production of other intermediate products or chemicals.

13 cl, 6 tbl, 18 ex

Description

The present invention relates to a process for the production of sugars from biomass derived from guayule plants.

More specifically, the present invention relates to a process for producing sugars from biomass derived from guayule plants, comprising contacting a certain amount of said biomass with a certain amount of water and at least one organic acid, and optionally at least one inorganic acid, to obtain a mixture, said at least one organic acid and said at least one inorganic acid, optionally present, are used in such quantities that the total number of moles of said at least one organic acid and said at least one inorganic acid , optionally present, contained in the specified mixture is calculated in accordance with the specific equations and the specific algorithm below.

The sugars thus obtained can advantageously be used as carbon sources in fermentation processes for the production of alcohols (e.g. ethanol, butanol), lipids, diols (e.g. 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2 ,3-butanediol) or in chemical synthesis processes to produce other intermediates or chemicals. These alcohols and lipids can, in turn, be used to advantage in the production of biofuels (e.g., biodiesel or "green diesel"), which can be used alone or blended with other automotive fuels, while these diols can be used in the production of products, such as, for example, biobutadiene, which, in turn, can be used in the production of rubbers (eg, polybutadiene or its copolymers). These uses are particularly important in the case of biorefining.

The production of sugars from biomass, in particular from lignocellulosic biomass, is known in the art.

Natural rubber is a hydrocarbon polymer (cis-1,4-polyisoprene) found in hundreds of plant species in the form of an aqueous emulsion commonly referred to as latex. The main source of natural rubber is Hevea brasiliensis, a tree native to the Amazon, and South America remained the main source for the limited amount of latex needed throughout the nineteenth century. Currently, American plantations have been almost completely abandoned due to pests and diseases, and natural rubber production is almost entirely concentrated in Southeast Asia.

To overcome the shortcomings of a manufacturing process that is always prone to disease and vermin attack, several methods for the production of synthetic rubbers were developed in the twentieth century, culminating in the discovery of Ziegler-Natta catalysts that can polymerize isoprene with very high regio- and stereoselectivity, yielding cis-1, 4 Synthetic polyisoprene that is virtually indistinguishable from plant origin. Natural rubber, however, has not been completely replaced because some of its mostly mechanical properties are actually a consequence of the small amount of lipids and proteins present in it. Thus, the total rubber production in 2013 (27.5 million tons) still included 12 million tons (43%) of natural rubber.

However, the production of rubber from Hevea brasiliensis entails some technical and ethical issues. In fact, it is always possible that the same diseases and parasites that have decimated American plantations may also be affecting diseases in Southeast Asia. In addition, the collection of latex requires a lot of labor and is profitable only because this labor is paid with extremely low wages. For these reasons, alternative sources of natural rubber are being sought. Among them, guayule (Parthenium argentatum) is certainly one of the most promising.

Guayule (Parthenium argentatum) is a perennial shrub native to the semi-desert regions of the southwestern United States (especially Texas) and northern Mexico. This plant accumulates natural rubber, mainly composed of cis-1,4-polyisoprene elastomer, in the form of latex (milky suspension or dispersion in water), especially in the bark of branches and stem. The content of natural rubber can depend on various environmental, cultivation and conservation factors and ranges from 5% to 20% of the total dry plant weight.

Extraction of natural rubber from the guayule plant (Parthenium argentatum) as well as other non-Hevea plants, such as the genera Asteraceae, Euphorbiaceae, Campanulaceae, Labiatae and Moraceae, such as, for example, Euphorbia lathyris, Parthenium incanum, Chrysothamnus nauseosus, Pedilanthus macrocarpus , Cryptostegia grandiflora, Asclepias syriaca, Asclepias speciosa, Asclepias subulata, Solidago altissima, Solidago gramnifolia, Solidago rigida, Sonchus arvensis, Silphium spp., Cacalia atriplicifolia, Taraxacum kok-saghyz, Pycnanthemum incanum, Teucreum canadense, Campanula americana "guayule type") is an important alternative to the extraction of natural rubber from Hevea brasiliensis, especially given the higher resistance of said species to pathogens affecting Hevea and the lower cost of importing raw materials of plant origin and due to the lower content of many protein contaminants responsible for type I (or IgE mediated) latex allergy in rubbers isolated from said plants compared to Hevea.

However, the production of natural rubber from guayule is only beneficial if all the other fractions that make up the plant are also used: mainly resin (present in amounts comparable to rubber) and lignocellulosic fraction, as well as small amounts of essential oils and waxes. In particular, after the extraction of rubber and resin, as detailed in the scientific and patent literature, the lignocellulosic residue (bagasse) containing lignin and polysaccharides must undergo a saccharification process, which consists of the hydrolysis of polysaccharides [which are thus converted into sugars having 5 carbon atoms (C5) and six carbon atoms (C6) dissolved in the obtained hydrolyzate], and leaves a solid residue containing lignin. The sugars thus obtained can then be used as feedstock in processes for the production of organic intermediates by fermentation, while the lignin can be used as fuel or in other ways.

It is important to note that while the natural rubber obtained from Hevea brasiliensis is obtained by harvesting the latex present in the milk ducts along the bark by incision to said ducts in the bark, the natural rubber of guayule accumulates inside the plant cells (stem, leaves and roots). ) and can be obtained by grinding plant material and collecting cellular components using physical and/or chemical methods.

For example, international patent application WO 2013/134430 describes a process for extracting natural rubber from non-Hevea plants, which involves harvesting guayule plants, removing most of the leaf parts, and partially drying the plant material. After crushing and grinding, the plant material is suspended in the presence of a polar organic solvent (eg acetone) and a non-polar organic solvent (eg hexane). After separating the bagasse from the slurry, a slurry containing rubber and resin, the miscella, is obtained. A more polar organic solvent is added to said miscella to cause the rubber to coagulate into particles which are separated by sedimentation.

Thus, when processing the guayule plant, a resin is obtained, consisting mainly of terpene compounds, mainly dispersed in the wood fraction. Guayule resin has long been used for a variety of purposes, including, for example, the production of adhesives and the production of pest-resistant wood panels. For this reason, importance is also given to isolating said resin in some of the processes described in the prior art.

For example, US Pat. No. 4,435,337 describes a process for recovering rubber, tar, water-soluble compounds, and bagasse. In particular, this method includes: (a) the stage of partial drying of plant material to a moisture content of from 5 to 25 wt.%; (b) extracting the resin with a substantially anhydrous oxygenated organic solvent (eg, anhydrous acetone); and (c) recovering rubber, water-soluble compounds, and bagasse by flotation of the rubber material. In said patent, it is noted that resin extraction is more efficient the lower the amount of water present in the extracting solvent; in addition, it has surprisingly been found that, for the extraction of resin from plant material, it is more advantageous to use concentrated resin containing miscella in relation to the use of fresh solvent.

US Patent Application 2014/0288255 describes a process for separating rubber, resin, and bagasse, comprising a first step of partially homogenizing the plant material in the presence of a medium capable of dissolving the resin, which is then separated from the bagasse; a second step of partially homogenizing the bagasse in the presence of a solvent capable of dissolving the rubber, which is then separated from the bagasse; a final drying step for rubber and bagasse, which may, for example, involve evaporation of the solvent in a thin film evaporator ("spread film evaporator") and extrusion of the rubber. The patent application also describes a process in which plant material is homogenized in the presence of a "grinding solvent" capable of dissolving rubber and resin, which are separated from each other in a later purification step using a fractionation solvent.

Lignocellulosic residue (bagasse), obtained after the extraction of latex and resin from guayule plants, is a complex structure consisting of three main components: cellulose, hemicellulose and lignin.

As is known in the art, the relative amounts of these three components in lignocellulosic biomass that can be used to produce sugars vary depending on the type of lignocellulosic biomass used. For example, these amounts vary depending on the species and age of the plant.

Cellulose is the main component of lignocellulosic biomass and is typically present in an amount of 30 wt.% to 60 wt.%, based on the total mass of lignocellulosic biomass. Cellulose consists of glucose molecules (approximately 500 to 10,000 units) linked to each other via a β-1,4 glucosidic bond. The formation of hydrogen bonds between the chains leads to the formation of crystalline domains, which gives resistance and elasticity to plant fibers. In nature, it can occur in its pure form only in annual plants such as cotton and flax, while in woody plants it is always accompanied by hemicellulose and lignin.

Hemicellulose, which is usually present in an amount of 10 wt.% to 40 wt.%, based on the total mass of lignocellulosic biomass, is a copolymer, relatively short (10 to 200 molecules) and branched, consisting of both sugars with six carbon atoms ( glucose, mannose, galactose), and from sugars with five carbon atoms (xylose, arabinose). Some important properties of plant fibers are due to the presence of hemicellulose, among which the main property is the tendency to saturate said plant fibers with moisture when water is present, resulting in swelling. Hemicellulose is also tacky and therefore tends to harden or keratinize, causing said vegetable fibers to become stiff and more slowly hydrated.

Lignin is typically present in an amount of 10% to 30% by weight, based on the total weight of the lignocellulosic biomass. Its main function is to bind and hold the various plant fibers together, giving the plant density and firmness, and it also provides protection from insects, pathogens, damage and ultraviolet radiation. It is mainly used as a fuel, but is currently also used in industry as a dispersant, curing agent, emulsifier for laminates, cardboard and rubber products. It can also be chemically processed to produce aromatic compounds such as vanillin, syringaldehyde, p-hydroxybenzaldehyde, which can be used in pharmaceuticals or in the cosmetics and food industries.

In order to optimize the conversion of lignocellulosic biomass into energy products, it is known to pretreat said biomass to separate lignin and hydrolyse cellulose and hemicellulose to simple sugars such as, for example, glucose and xylose, which are then subjected to fermentation processes.

The method commonly used for the above purpose is acid hydrolysis, which is carried out in the presence of dilute or concentrated strong acids.

For example, US 6423145 describes a process for hydrolyzing lignocellulosic biomass to produce a large amount of fermentable sugars, comprising: impregnating lignocellulosic material with a mixture containing a dilute acid as a catalyst (for example, sulfuric acid, hydrochloric acid, nitric acid, sulfur dioxide, or any other strong acid to achieve a pH less than about 3) and a metal salt catalyst (e.g., ferrous sulfate, ferric sulfate, ferric chloride, aluminum sulfate, aluminum chloride, magnesium sulfate), in such an amount as to provide a high yield fermentable sugars compared to that obtained in the presence of dilute acid alone; feeding the impregnated lignocellulosic material into the reactor and heating (for example, to a temperature of from 120°C to 240°C) for a period of time (for example, for a period of time from 1 min to 30 min) sufficient to hydrolyze essentially all of the hemicellulose and more 45% cellulose to water-soluble sugars; extraction of sugars soluble in water.

International patent application WO 2010/102060 describes a process for pre-treatment of biomass for use in a biomass processing plant to produce a fermentation product, comprising the steps of: treating (eg removing unwanted materials, grinding) the biomass before it is fed to the pre-treatment; pre-treatment of the biomass with a dilute acid (eg, sulfuric acid) at a concentration of from about 0.8 wt.% to about 1.1 wt.% at a temperature of from about 130°C to about 170°C, for a period of time from about 8 minutes up to about 12 minutes; where the fermentation product can be obtained by separating the pre-treated biomass into a liquid component, including xylose, and a solid component, from which glucose can be obtained, and extracting xylose for fermentation; wherein the biomass includes lignocellulosic material and the lignocellulosic material includes corn cobs, corn cob husks, corn leaves, and corn stalks.

International patent application WO 2010/071805 describes a process for pretreatment of lignocellulosic material, which includes: a first pretreatment of lignocellulosic material, carried out under mild operating conditions, to obtain a first product; contacting said first product with a dilute acid in aqueous solution (eg, sulfuric acid, sulfurous acid, sulfur dioxide, phosphoric acid, carbonic acid) to form a second product. The specified two-stage method allows you to provide products used to obtain bioethanol.

US 2010/0227369 describes a process for producing a fermentation product in a fermentation system from biomass that has been pre-treated and separated into a first component and a second component, said method comprising the steps of: supplying the first component to the fermentation system; supply to the fermentation system of an organism capable of producing ethanol ("ethanologen"); exposure of the first component and an organism capable of producing ethanol ("ethanologen") in the fermentation system at a temperature of from about 26°C to about 37°C and at a pH of from about 4.5 to about 6.0, for a period of time not less than 6 p.m.; removing the fermentation product from the fermentation system; wherein the organism capable of producing ethanol ("ethanologen") is fed into the fermentation system in an amount of less than 150 g of the organism capable of producing ethanol ("ethanologen") (dry weight) per liter of the first component; biomass includes lignocellulosic material; the lignocellulosic material includes at least one of the following: corn cobs, corn cob husks, corn leaves, and corn stalks; the first component includes pentose; pentose includes xylose; while an organism capable of producing ethanol (“ethanologen”) is able to ensure the fermentation of xylose into ethanol. Pretreatment of the biomass is preferably carried out by bringing said biomass into contact with an acid, such as, for example, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid or mixtures thereof.

Patent application US 2008/0274509 describes a method for producing a hydrolyzed product from lignocellulosic material, comprising: a) pre-treatment of said lignocellulosic material with a compound selected from the group consisting of sulfuric acid, alkalis, peroxodisulfates, potassium peroxide and mixtures thereof, in the presence of water , to obtain an aqueous phase and b) after removing the aqueous phase and washing the resulting product, treating said product with an enzyme used for hydrolysis in the presence of water to obtain a hydrolyzed product, said hydrolyzed product being suitable as a carbon source for fermentation

In Tsoutsos T. et al., Energies (2011), Vol. 4, pages 1601-1623, describes how to optimize the production of fermentable sugar solutions for the production of bioethanol from lignocellulosic biomass. In this regard, lignocellulosic biomass is subjected to a two-stage hydrolysis process in the presence of dilute acid. In particular, the tests were carried out in the presence of acids (eg hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid) diluted to a concentration of up to 3% - 4%, and at a temperature from 100°C to 240°C. Hydrolysis of hemicellulose proceeds at temperatures from 110°C to 140°C, while crystalline cellulose remains practically unchanged up to a temperature of 170°C and is hydrolyzed at a temperature of 240°C.

In Gonzales-Hernandez J.C. et al., Journal of the Mexican Chemical Society (2011), Vol. 56 (4), pages 395-401, describes the hydrolysis of polysaccharides from tamarind seeds. In particular, tamarind seeds are subjected to hydrolysis under various operating conditions: i.e. at a temperature of 86°C to 130.2°C; at a concentration of nitric acid or sulfuric acid from 0.32 vol. % to 3.68 vol. %; and at a contact time of 13.2 minutes to 40 minutes. It was observed that temperature and time are factors that mainly affect the hydrolysis of sugars: in particular, the best operating conditions for both acids were as follows: temperature equal to 130.2° C., concentration equal to 2 vol. %, contact time 30 min, with a sugar yield of approximately 110 g/L.

Shatalov A.A. et al., "Chemical Engineering & Process Technology" (2011), Vol. 2, Issue 5, pages 1-8, describes the preparation of xylose from thistles (Cynara cardunculus L.) by hydrolysis in the presence of dilute sulfuric acid, at low temperature, in one step. In particular, when working under optimal conditions, i.e. at a temperature of 138.5° C., a treatment time of 51.7 minutes, an acid concentration of 1.28%, an xylose recovery of 86%, with low cellulose degradation and low furfural production (glucose = 2.3 g and furfural (F) 1.04 g per 100 g of thistle).

However, the above methods have some disadvantages.

For example, if the acid hydrolysis is carried out at high temperatures, for example, above 140°C, by-products may be formed as a result of the hydration of sugars and the partial depolymerization of lignin, such as, for example, furfural (F), hydroxymethylfurfural (HMF), phenolic compounds, which act as inhibitors of the growth of microorganisms commonly used in subsequent sugar fermentation processes, resulting in a significant reduction in the efficiency and productivity of these processes.

On the other hand, if the acid hydrolysis is carried out at low temperatures, for example, less than 140° C., limited degradation of the lignocellulosic biomass can be obtained, and this destruction is necessary to release the cellulose fibers from the lignin lattice that surrounds them, in order to enable them to be used with advantage at the next stage of enzymatic hydrolysis. In fact, enzymes commonly used in enzymatic hydrolysis (eg, cellulase) find it difficult to reach cellulose fibers coated with lignin.

It is known in the art to overcome the above disadvantages.

For example, international patent application WO 2010/069583 describes a process for producing one or more sugars from a biomass containing at least one polysaccharide, comprising contacting the biomass with an aqueous solution of at least one organic acid, preferably p-toluenesulfonic acid, 2 -naphthalenesulfonic acid, 1,5-naphthalenesulfonic acid, at a temperature greater than or equal to 160°C, preferably from 160°C to 230°C. Said patent application also mentions alkyl sulfonic acids having 4 to 16 carbon atoms, preferably 8 to 12 carbon atoms, even more preferably octyl sulfonic acid and dodecyl sulfonic acid. However, hydrolysis examples are given that refer only to the use of 2-naphthalenesulfonic acid.

International patent application WO 2010/015404 describes a method for producing sugars from biomass containing at least one polysaccharide, which includes bringing the biomass into contact with an aqueous solution of at least one organic acid containing from 7 to 20 carbon atoms, preferably from 9 to 15 carbon atoms, more preferably p-toluenesulfonic acid, 2-naphthalenesulfonic acid, 1,5-naphthalenesulfonic acid, at a temperature of from 80°C to 140°C, preferably from 100°C to 125°C.

International patent application WO 2015/087254 in the name of the Applicant describes a process for the production of sugars from biomass comprising at least one polysaccharide, comprising bringing said biomass into contact with an aqueous solution of at least one organic acid containing 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, the pH of said aqueous solution is from 0.6 to 1.6, preferably from 0.9 to 1.3. Preferably, said at least one organic acid may be selected from among the alkyl sulfonic acids having the general formula (I):

R-SO ₃ H (I),

where R represents a linear or branched C ₁ -C ₆ alkyl group.

US Patent Application 2017/218094 in the name of the Applicant relates to an integrated process for the processing and use of each part of the guayule plant, including the following steps:

- separation of stems and branches from the leaves of the specified plant by mechanical processing;

- treatment of leaves to obtain waxes and essential oils and a fraction including cellulose, hemicellulose and, to a lesser extent, salts, organic compounds and lignin;

- extraction of the liquid phase from the stem and branches, resulting in the formation of the first solid woody residue, called bagasse;

- processing the specified first solid wood residue with the formation of sugars, cellulose, hemicellulose and lignin.

It is believed that the aforementioned integrated process can further utilize the guayule plant by combining the production of latex, rubber, resin and bagasse with the production of fermentable sugars. Fermentable sugars are obtained by subjecting the obtained bagasse to a two-stage saccharification treatment: in the first stage, acid hydrolysis is carried out in the presence of organic acids, such as, for example, alkylphosphonic or alkylsulfonic acids, to convert hemicellulose into monomeric sugars having 5 carbon atoms (C5), while on the second stage is carried out by enzymatic, chemical or thermochemical hydrolysis to obtain monomeric sugars having 6 carbon atoms (C6).

The Applicant noted, however, that the use of the organic acids described above having the general formula (I) does not always lead to the desired results, especially in terms of sugar yield and production of by-products, or when using biomass derived from guayule plants as such. , or by using bagasse obtained from extraction processes that guayule plants may have been subjected to, as is known in the art, as described, for example, in US patent application 2017/218094 or in international patent application WO 2017/103769 in the name of the applicant or in US Patent 4,435,337, for example:

- bagasse obtained using the process described in example 2 of US patent 4435337, included in the present description by reference [sample designated as GR-2 in said patent and designated as "bagasse (1)" in the following examples]; or

- bagasse obtained as a result of work in accordance with the processes described in examples 1-3 of the international patent application WO 2017/103769 in the name of the applicant, included in this description by reference [sample obtained after extraction of latex, resin and rubber, see .as "bagasse(2)" in the following examples].

In addition, since the production of fermentable sugars from biomass derived from guayule plants continues to be of particular interest, the development of new processes that provide this production can lead to desirable results, especially in terms of sugar yield and production through by-products, is also of interest. big interest.

Therefore, the applicant set himself the task of determining a method for the production of sugars from biomass obtained from guayule plants, in particular from bagasse obtained as a result of the extraction processes to which said guayule plants are subjected, which could overcome the aforementioned disadvantages. In particular, the applicant has set himself the task of determining a method for the production of sugars from biomass obtained from guayule plants, which could provide a high conversion of the hemicellulose component and, therefore, a high yield of sugars containing 5 carbon atoms (C5) and 6 carbon atoms (C6) , in particular sugars having 5 carbon atoms (C5), such as xylose, arabinose (i.e. the yield of sugars of 5 carbon atoms (C5) and 6 carbon atoms (C6) is greater than or equal to 95%, and the specified yield is calculated by relative to the total amount of hemicellulose present in the original biomass) and a small amount of by-products (e.g., furfural (F), hydroxymethylfurfural (HMF)) (i.e. the amount of by-products is less than or equal to 5%, and this amount is calculated as described below).

Applicant has now found that the production of sugars from biomass derived from guayule plants, in particular from bagasse obtained from the extraction processes to which said guayule plants are subjected, can advantageously be carried out by a process comprising bringing a certain amount of said biomass into contact with a certain amount of water and at least one organic acid and optionally at least one inorganic acid, obtaining a mixture of said at least one organic acid and said at least one inorganic acid, optionally present, is used in such amounts that the total number of moles of said at least one organic acid and said at least one inorganic acid optionally present in said mixture is calculated in accordance with the specific equations and the specific algorithm below.

There are a number of benefits that can be obtained with this process. For example, this method provides a high conversion of the hemicellulose component and, consequently, a high yield of sugars having 5 carbon atoms (C5) and 6 carbon atoms (C6), in particular sugars having 5 carbon atoms (C5), such as xylose, arabinose ( i.e. the yield of sugars having 5 carbon atoms (C5) and 6 carbon atoms (C6) is greater than or equal to 95%), said yield being calculated with respect to the total amount of hemicellulose present in the original biomass obtained from the guayule plant ) resulting from the acid hydrolysis of said guayule biomass, which can then be used as a carbon source in fermentation processes to produce alcohols (e.g. ethanol, butanol), lipids, diols (e.g. 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol) or in chemical synthesis processes to produce other intermediates or chemicals. These alcohols and lipids can in turn be used to advantage in the production of biofuels (e.g., biodiesel or "green diesel"), which can be used alone or blended with other automotive fuels, while these diols can be used in the production of products such as such as, for example, biobutadiene, which, in turn, can be used in the production of rubbers (for example, polybutadiene or its copolymers). These uses are particularly important in the case of biorefining.

In addition, the possibility of obtaining an extensive conversion of the hemicellulose component and, consequently, a high yield of sugars having 5 carbon atoms (C5) and 6 carbon atoms (C6), in particular sugars having 5 carbon atoms (C5), such as xylose, arabinose, allows send sugar solutions that are especially rich in sugars having 5 carbon atoms (C5) or mixtures of said sugar solutions that are especially rich in sugars having 5 carbon atoms (C5) and solutions that are especially rich in sugars having 6 carbon atoms (C6 ) (for example, sugar solutions resulting from the enzymatic hydrolysis of cellulose) for subsequent fermentation and, as a result, for optimizing said fermentation processes. In fact, it is known that the microorganisms used in the fermentation process produce fermented biomass with characteristics that differ, for example, in terms of the accumulation of intermediates and undesired metabolic products, depending on the sugars contained in the raw material. It is also known that microorganisms used in fermentation processes are sensitive to their food: for example, some strains of microorganisms do not tolerate excessive amounts of sugars having 5 carbon atoms (C5). It is therefore extremely advantageous to have two different types of sugar solutions, i.e. both sugar solutions especially rich in 5 carbon sugars (C5) and sugar solutions especially rich in 6 carbon sugars (C6), so that these sugar solutions are designed to different fermentation processes, therefore optimizing said fermentation processes by better matching the nutritional needs of different strains of microorganisms.

It should also be noted that the amount of sugars having 5 carbon atoms (C5) and 6 carbon atoms (C6) obtained from the hydrolysis of hemicellulose depends on the nature of the original guayule bagasse: in fact it is known, as mentioned above, that the amounts of cellulose components, hemicellulose and lignin vary depending on the type of biomass.

In addition, this method allows you to work in a wide temperature range (i.e. in the temperature range from 100 to 180 ° C) and even at high temperatures (i.e. at temperatures of 140 ° C or more) to obtain a small amount of by-products [for example, furfural (F), hydroxymethylfurfural (HMF)], which, as mentioned above, act as growth inhibitors of microorganisms commonly used in subsequent sugar fermentation processes.

In addition, the ability to operate over this wide temperature range is a significant industrial advantage because the unexpected temperature increase in reactors in which the biomass is in contact with water, at least one organic acid, and optionally at least , inorganic acid alone does not increase the production of by-products [eg, furfural (F), hydroxymethylfurfural (HMF)], as is typically the case in prior art processes.

In addition, the possibility of replacing some of said at least one organic acid with at least one inorganic acid allows for cost savings and therefore an economic advantage.

Thus, the aim of the present invention is a method for obtaining sugars from biomass obtained from guayule plants, comprising contacting an amount of said biomass (G ₂ ) (g) with an amount of water (G ₁ ) (g) and with at least one organic acid and, optionally, at least one inorganic acid, obtaining a mixture, wherein said at least one organic acid and said at least one inorganic acid, optionally present, are used in such quantities that the total number of moles of said at least one organic acid and said at least one optionally present inorganic acid (m _TOT ) contained in said mixture is calculated according to the following equation (1):

m _TOT = m ₁ + m ₂ (1),

where m ₁ and m ₂ are defined according to the following equations (2) and (3) respectively:

m ₁ \u003d R ₁ G ₁ (2),

m ₂ \u003d R ₂ G ₂ (3),

wherein:

- R ₁ (mmol/g) is the ratio between the first amount of said at least one organic acid (mmol) and the first amount of said at least one inorganic acid (mmol), optionally present, and the amount of water used G ₁ ( d), R ₁ is from 0.06 to 0.25 mmol/g, preferably from 0.09 to 0.18 mmol/g, said first amount of said at least one organic acid (mmol) and said first amount the specified at least one inorganic acid (mmol) is optionally present depending on the amount of water G ₁ (g);

- R ₂ (mmol/g) is:

- in the absence of said at least one inorganic acid, the ratio between the second amount of said at least one organic acid (mmol) and the amount of biomass used G ₂ (g); or

- in the presence of said at least one inorganic acid, the ratio between the sum of said second amount of said at least one organic acid (mmol) and the second amount of said at least one inorganic acid (mmol) and the amount of biomass used G ₂ (d); or

- in the presence of said second amount of said at least one inorganic acid (mmol) and in the absence of said second amount of said at least one organic acid (mmol), the ratio between said second amount of said at least one inorganic acid (mmol ) and the amount of biomass used G ₂ (g); said second amount of said at least one organic acid (mmol) and said second amount of said at least one inorganic acid (mmol) depends on the amount of biomass G ₂ (g);

R ₂ is from 0.90 R (mmol/g) to 1.10 R (mmol/g), preferably from 0.95 R (mmol/g) to 1.05 R (mmol/g), R is determined by the following algorithm (4), the specified algorithm (4) is obtained through the following elementary operations:

(i) obtaining a volume V (l) of an aqueous solution of said at least one organic acid and said at least one first amount of said at least one inorganic acid (mmol), optionally present, said aqueous solution having a pH of ₍₁₎ ) lower than 7, preferably from 0.7 to 3;

(ii) adding an amount of biomass Q (g) dried at 120°C for 15 hours to the aqueous solution obtained in (i), said amount of biomass being preferably less than or equal to 60% by weight, more preferably 2 to 40 wt.% in relation to the total mass of the resulting mixture;

(iii) measuring the pH of the mixture obtained in (ii), and the specified pH value is indicated below as pH ₍₂₎ ;

(iv) determining R according to the following algorithm (4):

R = (10 ^-pH ₍₁₎ - 10 ^-pH ₍₂₎ ) 1000 V/Q) (4)

where pH ₍₁₎ , pH ₍₂₎ , V and Q have the same values as above, the above elementary operations are performed at room temperature;

provided that said at least one organic acid is present in such an amount that the ratio R _MINIMUM (mmol/g) is determined according to the following equation (5):

R _MINIMUM = m _{ORGANIC ACID} / G ₂ (5)

where m _{ORGANIC ACID} is mmol organic acid present and G ₂ has the same meaning as above, is greater than or equal to 0.20 mmol/g or greater, preferably greater than or equal to 0.25 mmol/g, and if said at least one inorganic acid is present, wherein said mmol of organic acid (m _{ORGANIC ACID} ) is present in an amount less than the sum of two amounts of acid, i.e. the sum of the amount of inorganic acid (mmol) and the amount of organic acid (mmol), this sum corresponds to the total number of moles m _TOT (mmol) as defined in equation (1) above.

For the purposes of the present description and the following claims, the specified algorithm should be understood as being represented by an ordered and finite sequence of elementary operations, which leads to a given result in a finite time. In particular, its constituent operations are "elementary", that is, they cannot be further broken down; its constituent elementary operations can be unambiguously interpreted by the operator, whether human or artificial, that is, unambiguously; the algorithm consists of a finite number of elementary operations and requires a finite amount of input data; the execution ends after a finite time, and the execution leads to a unique result.

For the purposes of this description and the following claims, definitions of numerical ranges always include extreme values unless otherwise indicated.

For the purposes of the present description and the following claims, the term "comprising" also includes the terms "which essentially consists of" or "which consists of".

For the purposes of the present description and the following claims, the term "guaiule plants" refers generally to both the species Parthenium argentatum and the guaiule plants of the species listed above.

For the purposes of this description and the following claims, the term "sugars having 5 carbon atoms (C5)" means pentose sugars, or more simply pentoses, which are five-carbon monosaccharide carbohydrates having the chemical formula C ₅ H ₁₀ O ₅ . Similarly, for the purposes of this description and the following claims, the term "sugars having 6 carbon atoms (C6)" means hexose sugars or, more simply, hexoses, which are six-carbon monosaccharide carbohydrates having the chemical formula C ₆ H ₁₂ O ₆ .

For the purposes of this description and the following claims, the term "biomass derived from guayule plants" means any form (e.g., whole plant, plant parts including roots, branches and/or stems, leaves, bark, if present, plant fragments obtained by grinding , grinding, etc., briquettes and pellets obtained by pressing plant fragments), where guayule plants are used to obtain latex, rubber, resin, bagasse, sugars and other components present in the plants themselves through chemical and / or physical methods.

For the purposes of this specification and the following claims, "bagasse" means the residual amount of plant material resulting from the extraction processes to which guayule plants may be subjected. In addition to lignin and polysaccharides (eg cellulose and hemicellulose), bagasse may also contain small amounts of non-plant material (eg potting mix, sand, etc.) usually associated with plant roots and derived from nutrient media.

For the purposes of this description and the following claims, the term "room temperature" means a temperature between 15°C and 30°C.

It should be noted that for the purposes of the present invention, both the pH of an aqueous solution of said at least one organic acid and said at least one first amount of said at least one inorganic acid, optionally present, obtained in (i ), i.e. The pH ₍₁₎ and the pH of the mixture obtained in (ii), ie pH ₍₂₎ , can be controlled using techniques known in the art. Preferably, for the purposes of the present invention, they are constantly monitored by a pH meter.

According to a preferred embodiment of the present invention, said biomass derived from guayule plants is bagasse from the extraction processes to which said guayule plants are subjected.

As mentioned above, the extraction methods that guayule plants can undergo to obtain bagasse are known in the art, as described, for example, in US patent application 2017/218094 or in international patent application WO 2017/103769 in the name of the Applicant mentioned above, or US Pat. No. 4,435,337 cited above. For the purposes of the present invention, said bagasse can preferably be obtained by proceeding as above, i.e.:

- bagasse obtained using the process described in example 2 of US patent No. 4435337, included as a reference [sample designated as GR-2 in said patent and designated as "bagasse (1)" in the following examples]; or

- bagasse obtained as a result of working in accordance with the process described in examples 1-3 of the international patent application WO 2017/103769 in the name of the applicant, included by reference (the sample obtained after the extraction of latex, resin and rubber is indicated as " bagasse (2)" in the following examples).

According to a preferred embodiment of the present invention, such biomass may be subjected to a pre-grinding process before being brought into contact with water and said at least one organic acid and said at least one inorganic acid, which is optionally present. Preferably, said biomass may be ground to particles having a diameter of 0.1 to 10 mm, more preferably 0.5 to 4 mm. Particles having a diameter of less than 2 mm are particularly preferred.

According to a preferred embodiment of the present invention, said at least one organic acid may be selected, for example, from alkyl sulfonic acids having the general formula (I):

R-SO ₃ H (I),

where R represents a linear or branched C ₁ -C ₆ preferably C ₁ -C ₃ alkyl group.

According to a particularly preferred embodiment of the present invention, said at least one organic acid is methanesulfonic acid (CH ₃ -SO ₃ H).

According to a preferred embodiment of the present invention, said at least one inorganic acid can be selected, for example, from strong inorganic acids such as, for example, hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ) or mixtures thereof.

According to a particularly preferred embodiment of the present invention, said at least one inorganic acid is sulfuric acid (H ₂ SO ₄ ).

It should be noted that for the purposes of the method which is the object of the present invention, the presence of at least one organic acid is essential. In fact, as will be seen from the following examples, the use of an inorganic acid alone will not provide the desired high performance in terms of hemicellulose conversion present in biomass derived from guayule plants, especially bagasse, and sugar selectivity. In fact, the use of an inorganic acid in itself leads to a deterioration in hemicellulose conversion performance and sugar selectivity. After this observation, it is also surprising that the partial replacement of an organic acid with an inorganic acid does not affect the throughput of the process, which is in fact completely comparable to that obtained using only an organic acid. As mentioned above, the partial replacement of an organic acid with an inorganic acid results in cost savings and therefore an economic advantage.

According to a preferred embodiment of the present invention, said process for producing sugars from biomass derived from guayule plants comprises:

(a) bringing an amount of said biomass (G ₂ ) (g) into contact with an amount of water (G ₁ ) (g) and at least one organic acid and optionally at least one inorganic acid in a reactor, which leads to the first reaction mixture;

(b) heating the reactor to the desired temperature, preferably 100 to 180°C, more preferably 130 to 150°C, over a period of 20 minutes to 2 hours, preferably 40 minutes to 1 hour, resulting in a second reaction mixture, containing the first solid phase and the first aqueous phase;

(c) optionally maintaining said second reaction mixture containing the first solid phase and the first aqueous phase at said desired temperature for 30 seconds to 1 hour, preferably 5 minutes to 20 minutes;

(d) withdrawing said second reaction mixture from said reactor.

It should be noted that for the purposes of the present invention in step (a), the sequence in which the components, namely biomass, water, organic acid and possibly inorganic acid, are in contact is irrelevant for the purposes of the present invention. In particular, any sequence in which these components are in contact will be an embodiment of the present invention. The amounts of said at least one organic acid and optionally at least one inorganic acid must correspond to the R ₁ , R ₂ and R _MINIMUM values defined above.

In accordance with a preferred embodiment of the present invention, said biomass may be present in said first reaction mixture in an amount of from 1 to 60 wt.%, preferably from 5 to 45 wt.%, even more preferably from 10 wt.% and 30 wt.% according to relative to the total weight of the specified first reaction mixture.

For the purposes of the present invention, said reactor may be selected from reactors known in the art, such as, for example, autoclaves, fixed bed reactors, continuous biomass slurry reactors (CSTR - Continuous Stirred Reactor), extruders.

According to a preferred embodiment of the present invention, said reactor is selected from continuous biomass slurry reactors (CSTR - mechanically stirred continuous reactor).

According to a preferred embodiment of the present invention, said first solid phase comprises lignin and cellulose, and said first aqueous phase contains at least one sugar having 5 carbon atoms (C5) and optionally at least one sugar, having 6 carbon atoms (C6) and said at least one organic acid and optionally said at least one inorganic acid. Said at least one organic acid and optionally said at least one inorganic acid is an organic acid and optionally an inorganic acid that is in contact with the biomass. Said at least one sugar is in particular xylose. Said xylose is a derivative of the acid hydrolysis of hemicellulose. Arabinose, mannose, galactose, glucose may also be present in said first aqueous phase.

Said first solid phase and said first aqueous phase may be separated by methods known in the art, such as, for example, filtration, centrifugation.

Preferably, said phases are separated by filtration.

In order to extract said sugar having 5 carbon atoms (C5), said sugar having 6 carbon atoms (C6), optionally present, and said at least one organic acid from said first aqueous phase, said first aqueous phase may be subjected to treatments known in the art. in the state of the art. For example, said first aqueous phase may be subjected to a resin separation step as described, for example, in US Pat. Nos. 5,726,046 and US 5,820,687. at least one inorganic acid, and a second aqueous phase containing at least one sugar having 5 carbon atoms (C5) and optionally at least one sugar having 6 carbon atoms (C6).

Said organic acid and said at least one inorganic acid, optionally present, can then subsequently be reused in accordance with the method of the present invention.

Said second aqueous phase containing at least one sugar having 5 carbon atoms (C5) and optionally at least one sugar having 6 carbon atoms (C6) can be used as such or mixed with solutions , especially rich in sugars having 6 carbon atoms (C6), in fermentation processes for the production of alcohols (e.g. ethanol, butanol), lipids, diols (e.g. 1,3-propanediol, 1,3-butanediol, 1,4-butanediol , 2,3-butanediol) or in chemical synthesis processes to produce other intermediates or chemicals. These alcohols and lipids can, in turn, be used to advantage in the production of biofuels (e.g., biodiesel or "green diesel"), which can be used alone or blended with other automotive fuels, while these diols can be used in the production of products such as such as, for example, biobutadiene, which, in turn, can be used in the production of rubbers (for example, polybutadiene or its copolymers). These uses are particularly important in the case of biorefining.

As mentioned above, the method which is the object of the present invention makes it possible to obtain at least one sugar having 5 carbon atoms (C5) and optionally at least one sugar having 6 carbon atoms (C6), in in particular, at least one sugar with 5 carbon atoms (C5), such as xylose, arabinose, from acid hydrolysis of hemicellulose in high yield. More specifically, this method allows to obtain a yield of sugar having 5 carbon atoms (C5) and sugar having 6 carbon atoms (C6) greater than or equal to 95%, and said yield is calculated in relation to the total amount of hemicellulose present in the original biomass . In addition, the method which is the object of the present invention makes it possible to obtain a content (%) of a sugar having 5 carbon atoms (C5) greater than or equal to 70%, said content being calculated as described below.

The method which is the object of the present invention also allows high yields of cellulose and lignin to be obtained.

Said first solid phase containing cellulose and lignin obtained according to the method of the present invention can be used in an enzymatic hydrolysis process to hydrolyse cellulose to glucose. The enzymatic hydrolysis process can be carried out according to techniques known in the art, as described, for example, in US Pat. (Rohm Enzymes), Spezyme (Genecor), Novozym 188 (Novozymes), used alone or in a mixture of the same.

As a result of enzymatic hydrolysis of said first solid phase, a second solid phase containing lignin and a third aqueous phase containing glucose obtained from the hydrolysis of cellulose are obtained.

Said second solid phase and said third liquid phase may be separated by methods known in the art, such as, for example, filtration or centrifugation. Preferably, said phases are separated by filtration.

Said third aqueous phase containing glucose can be used as such or mixed with solutions especially rich in sugars having 5 carbon atoms (C5) as feedstock in fermentation processes for alcohols (e.g. ethanol, butanol), lipids, diols ( e.g. 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol) or in chemical synthesis processes to produce other intermediates or chemicals. Said alcohols and lipids may, in turn, be predominantly used in the manufacture of biofuels (e.g., biodiesel or "green diesel"), which may be used alone or blended with other automotive fuels, while said diols may be used in the manufacture of products such as such as, for example, biobutadiene, which, in turn, can be used in the production of rubbers (for example, polybutadiene or its copolymers). These uses are particularly important in the case of biorefining.

This second solid phase containing lignin can be used as a fuel, for example, as a fuel for the production of energy needed to support the processing of biomass.

Fermentation processes are described in the art, for example, in US patent application US 2013/0224333 and international patent application WO 2008/141317 (fermentation in the presence of yeast); or in US patent application US 2010/0305341 and international patent application WO 2011/051977 (fermentation in the presence of genetically modified buttery yeast); or in international patent application WO 2010/127319 (fermentation in the presence of genetically modified microorganisms).

In order to better understand the present invention and to put it into practice, some illustrative and non-limiting examples are given below.

Methods of analysis and characteristics

The analysis methods and characterizations listed below were used.

Analysis of initial biomass

The starting biomass was analyzed using Van-Soest's Fibrous Fraction System to quantify cell wall components, in particular hemicellulose, cellulose, and lignin, as described, for example, in Van Soest, P.J. and Wine, R.H. “Use of detergents in the analysis of fibrous feeds. IV. Determination of plant cell-wall constituents", Journal of Association of Official Analytical Chemistry (1967), Vol. 50, pg. 50-55.

Analysis of compounds present in the first aqueous phase

The sugars present in the first aqueous phase were analyzed by ion chromatography using the following operating conditions:

- instrument: column Dionex IC3000, PA100;

eluent: sodium hydroxide (NaOH) (100 mM)-sodium acetate (CH ₃ COONa) 0.6 M in 200 mM sodium hydroxide (NaOH);

- elution program: gradient, electrochemical detector.

By-products, i.e. furfural (F) and hydroxymethylfurfural (HMF) present in the first aqueous phase, were analyzed by liquid chromatography using the following operating conditions:

- Device: HP 1100, column Inertsil C18;

- eluent: 0.01 M phosphoric acid - acetonitrile (CH ₃ CN);

- elution program: gradient, UV-DAD detector.

Calculation of Yield, C5 Sugars (C5) and Production of By-Products

The yield was expressed based on the results of the assays (i.e. the analysis of compounds present in the first aqueous phase as described above) as a percentage between sugars having 5 carbon atoms (C5) and 6 carbon atoms (C6) [i.e. . pentoses (C5) and hexoses (C6) respectively] present in said first aqueous phase and the total amount of hemicellulose present in the original biomass according to the following formula:

Yield = (mC5 + mC6) / mHEMICELLULOSE * 100

wherein:

- C5 = pentoses present in solution;

- C6 = hexoses present in solution;

- m = mass of the connection;

- HEMICELLULOSE = hemicellulose present in the original biomass.

For each example, the content (%) of sugars having 5 carbon atoms (C5) (i.e., pentoses) present in the first aqueous phase was also determined by the following formula:

C5 content = mC5 / (mC5 + mC6) .100

where C5, C6 and m are as defined above.

In order to effectively express the formation of by-products, i.e. hydroxymethylfurfural (HMF) and furfural (F), the decomposition coefficients were calculated using the following formulas:

Degradation C6 = mHMF / (mC6 + mHMF) .100

Decomposition factor C5 = mF / (mC5 + mF) * 100

where C5, C6 and m have the meanings above;

- F = furfural;

- HMF = hydroxymethylfurfural.

Determination of R by algorithm (4)

The same process was followed for both bagasse (1) and bagasse (2). In detail, a solution of methanesulfonic acid (CH ₃ -SO ₃ H) was prepared at pH=0.9 by adding an appropriate amount of methanesulfonic acid (CH ₃ -SO ₃ H) to 100 ml of water at room temperature, stirred vigorously at 600 rpm with magnetic stirrer in a 200 ml beaker. The operation was monitored with a pH meter electrode (Metrohm 781 pH/Ion meter) placed in contact with the solution. To this solution was added 21 g of biomass [bagasse (1) or bagasse (2), respectively). The resulting mixture was constantly stirred vigorously (600 rpm) during the addition operation and then until the pH stabilized: the pH electrode meter (Metrohm 781, pH/Ion meter) was in contact with the resulting mixture throughout the entire sequence operations. Said pH stability was achieved 15 minutes after addition at pH 2.02. Algorithm (4), which is shown below for convenience, was then used to determine the value of R:

R \u003d (10 ^-pH ₍₁ ) - 10 ^-pH ₍₂₎ ) 1000 V / Q

wherein:

- pH ₍₁₎ = 0.9;

- pH ₍₂₎ = 2.02;

- V (l) = 0.1;

Q(r) = 21;

obtaining an R value of 0.55 mmol/g for both bagasse (1) and bagasse (2).

Example 1 (comparative)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (1) obtained from previously ground guayule plants (Parthenium argentatum) (sieved from 2 to 2 mm) (R ₂ =0.00 mmol/g; R _MINIMUM = 0.82 mmol/g) was added.

The first reaction mixture thus obtained was vigorously stirred (600 rpm) until a temperature of 140°C was reached within 45 minutes, as a result of which a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars. derived from hemicellulose.

After the autoclave had cooled to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids, mineral salts, resin and residual rubber.

The first aqueous phase was analyzed as described above, giving the following results (shown in Table 1):

- yield: 80.3% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 0.7%;

- C5 content: 79.4%.

EXAMPLE 2 (comparative)

885 g of water and 10.7 g (109.1 mmol) of sulfuric acid (H ₂ SO ₄ ) (the first amount of inorganic acid) were placed in a 2 L Brignole autoclave in open air (R1 = 0.12 mmol/g). Then 135 g bagasse (1) obtained from previously milled guayule plants (Parthenium argentatum) (sieved from 2 to 2 mm) (R2 = 0.00 mmol/g; R _MINIMUM = 0.00 mmol/g) was added.

The first reaction mixture thus obtained was vigorously stirred (600 rpm) until a temperature of 140°C was reached within 45 minutes, as a result of which a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars. derived from hemicellulose.

After the autoclave had cooled to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids, mineral salts, resin and residual rubber.

The first aqueous phase was analyzed as described above, giving the following results (shown in Table 1):

- yield: 69.1% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 1.7%;

- decomposition of C5: 3.2%;

- C5 content: 72.6%.

EXAMPLE 3 (invention)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (1) obtained from previously milled guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.1 g (73.9 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (second amount of organic acid) determined according to equation (1) and the following equations (R ₂ = 0.55 mmol/ g; R _MINIMUM = 1.37 mmol/g): m _TOT = 185.2 mmol was added in total.

The first reaction mixture thus obtained was intensively stirred (600 rpm) until a temperature of 140°C was reached within 45 minutes, resulting in a second reaction mixture containing a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars from hemicellulose.

After the autoclave had cooled to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids, mineral salts, resin and residual rubber.

The first aqueous phase was analyzed as described above, giving the following results (shown in Table 1):

- yield: 95.0% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 4.6%;

- C5 content: 80.5%.

EXAMPLE 4 (comparative)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g bagasse (2) obtained from previously milled guayule plants (Parthenium argentatum) (screened to below 2 mm) was added (R ₂ = 0.00 mmol/g; R _MINIMUM = 0.82 mmol/g).

The first reaction mixture thus obtained was vigorously stirred (600 rpm) until a temperature of 140°C was reached for 45 minutes, resulting in a second reaction mixture containing a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars. from hemicellulose.

After the autoclave had cooled to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.2 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt. % lignin relative to the total mass of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above, giving the following results (shown in Table 2):

- yield: 79.9% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 0.6%;

- C5 content: 80.4%.

EXAMPLE 5 (comparative)

885 g of water and 10.7 g (109.1 mmol) of sulfuric acid (H ₂ SO ₄ ) (the first amount of inorganic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ =0.12 mmol/g). Then 135 g bagasse (2) obtained from previously milled guayule plants (Parthenium argentatum) (screened to below 2 mm) was added (R ₂ = 0.00 mmol/g; R _MINIMUM = 0.00 mmol/g).

The first reaction mixture thus obtained was vigorously stirred (600 rpm) until a temperature of 140°C was reached within 45 minutes, as a result of which a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars. derived from hemicellulose.

After the autoclave had cooled to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.0 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above, giving the following results (shown in Table 2):

- yield: 68.4% (relative to the total amount of hemicellulose present in the original biomass);

- C6 degradation: 2.4%;

- decomposition of C5: 3.6%;

- C5 content: 70.1%.

EXAMPLE 6 (invention)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.1 g (73.9 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (second amount of organic acid) determined according to equation (1) and the following equations (R ₂ = 0.55 mmol/ g; R _MINIMUM = 1.37 mmol/g) total was added: m _TOT = 185.2 mmol.

The first reaction mixture thus obtained was vigorously stirred (600 rpm) until a temperature of 140°C was reached within 45 minutes, as a result of which a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose and a first aqueous phase containing sugars. derived from hemicellulose.

After the autoclave had cooled to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.0 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above, giving the following results (shown in Table 2):

- yield: 95.2% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 4.4%;

- C5 content: 80.7%.

EXAMPLE 7 (according to the invention)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (1) obtained from pre-crushed guayule plants (Parthenium argentatum) (particle size down to less than 2 mm) was added. Finally, 7.1 g (72.4 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, determined according to equation (1) and the following equations (R ₂ = 0.54 mmol/g; R _MINIMUM = 0.82 mmol/g): m _TOT = 183.7 mmol was added in total.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin in relation to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids, mineral salts, resin and residual rubber.

The first aqueous phase was analyzed as described above with the following results (shown in Table 1 and Table 3):

- yield: 95.1% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 4.5%;

- C5 content: 80.1%.

EXAMPLE 8 (invention)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.1 g (72.4 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, determined according to equation (1) and the following equations (R ₂ = 0.54 mmol/g; R _MINIMUM = 0.82 mmol/g): total added m _TOT = 183.7 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.0 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above, with the following results (shown in Table 2 and Table 4):

- yield: 95.4% (relative to the total amount of hemicellulose present in the original biomass);

- degradation of C6: 0.0%;

- degradation of C5: 4.5%;

- C5 content: 80.3%.

EXAMPLE 9 (comparative)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (1) obtained from pre-crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 3.0 g (30.6 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) is less than that determined according to equation (1) and the following equations (R ₂ = 0.23 mmol/g; R _MINIMUM = 0.82 mmol/g) was added: total added m _TOT = 141.9 mmol.

The first reaction mixture thus obtained was kept under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin in relation to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids, mineral salts, resin and residual rubber.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 3):

- yield: 87.8% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- C5 decomposition: 3.9%;

- C5 content: 80.1%.

EXAMPLE 10 (comparative)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (1) obtained from pre-crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 11.0 g (112.2 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid), more than that determined by equation (1) and the following equations (R ₂ = 0.82 mmol/g; R _MINIMUM = 0.82 mmol/g) added: total added m _TOT = 223.5 mmol.

The first reaction mixture thus obtained was kept under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin in relation to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids, mineral salts, resin and residual rubber.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 3):

- yield: 86.1% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 7.2%;

- C5 content: 74.3%.

EXAMPLE 11 (comparative)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 3.0 g (30.6 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) is added, less than that determined according to equation (1) and the following equations (R ₂ = 0.23 mmol/g; R _MINIMUM = 0.82 mmol/g): total added m _TOT = 141.9 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.0 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 4):

- yield: 84.7% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 3.2%;

- C5 content: 80.5%.

EXAMPLE 12 (comparative)

885 g of water and 10.7 g (111.3 mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) (the first amount of organic acid) were placed in a 2 L Brignole autoclave in open air (R ₁ = 0.13 mmol/g ). Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 11.0 g (112.2 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, less than that determined according to equation (1) and the following equations (R ₂ = 0.82 mmol/g; R _MINIMUM = 0.82 mmol/g): total added m _TOT = 223.5 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.0 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 4):

- yield: 86.3% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 4.3%;

- decomposition of C5: 7.4%;

- C5 content: 71.3%.

EXAMPLE 13 (comparative)

885 g water and 5.3 g (55.14 mmol) methanesulfonic acid (CH ₃ -SO ₃ H) (first amount of organic acid) and 5.5 g (56.2 mmol) sulfuric acid (H ₂ SO ₄ ) ( the first amount of inorganic acid) (R ₁ = 0.13 mmol/g) was placed in a 2 L Brignole autoclave in the open air. Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.0 g (71.4 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, determined according to equation (1) and the following equations (R ₂ = 0.53 mmol/g; R _MINIMUM = 0.41 mmol/g): total added m _TOT = 182.7 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 5):

- yield: 96.0% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- C5 decomposition: 4.6%;

- C5 content: 81.2%.

EXAMPLE 14 (according to the invention)

885 g water and 3.3 g (34.3 mmol) methanesulfonic acid (CH ₃ -SO ₃ H) (first amount of organic acid) and 7.6 g (77.5 mmol) sulfuric acid (H ₂ SO ₄ ) ( the first amount of inorganic acid) (R ₁ = 0.13 mmol/g) was placed in a 2 L Brignole autoclave in the open air. Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.0 g (71.4 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, determined according to equation (1) and the following equations (R ₂ = 0.53 mmol/g; R _MINIMUM = 0.25 mmol/g): total added m _TOT = 183.2 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 5):

- yield: 95.4% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 4.2%;

- C5 content: 79.8%.

EXAMPLE 15 (comparative)

885 g water and 2.1 g (21.8 mmol) methanesulfonic acid (CH ₃ -SO ₃ H) (first amount of organic acid) and 8.7 g (88.7 mmol) sulfuric acid (H ₂ SO ₄ ) ( the first amount of inorganic acid) (R ₁ = 0.13 mmol/g) was placed in a 2 L Brignole autoclave in the open air. Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.0 g (71.4 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, determined according to equation (1) and the following equations (R ₂ = 0.53 mmol/g; R _MINIMUM = 0.16 mmol/g): total added m _TOT = 181.9 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 42.3 wt.% cellulose, 18.2 wt.% hemicellulose, 24.1 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 5):

- yield: 81.4% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 1.1%;

- C5 content: 79.2%.

EXAMPLE 16 (according to the invention)

885 g water and 5.3 g (55.14 mmol) methanesulfonic acid (CH ₃ -SO ₃ H) (first amount of organic acid) and 5.5 g (56.2 mmol) sulfuric acid (H ₂ SO ₄ ) ( the first amount of inorganic acid) (R ₁ = 0.13 mmol/g) was placed in a 2 L Brignole autoclave in the open air. Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.0 g (71.4 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, determined according to equation (1) and the following equations (R ₂ = 0.53 mmol/g; R _MINIMUM = 0.41 mmol/g): total added m _TOT = 182.7 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.0 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 6):

- yield: 95.2% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 4.3%;

- C5 content: 80.7%.

EXAMPLE 17 (according to the invention)

885 g water and 3.3 g (34.3 mmol) methanesulfonic acid (CH ₃ -SO ₃ H) (first amount of organic acid) and 7.6 g (77.5 mmol) sulfuric acid (H ₂ SO ₄ ) ( the first amount of inorganic acid) (R ₁ = 0.13 mmol/g) was placed in a 2 L Brignole autoclave in the open air. Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.0 g (71.4 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, determined according to equation (1) and the following equations (R ₂ = 0.53 mmol/g; R _MINIMUM = 0.25 mmol/g): total added m _TOT = 183.2 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.0 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 6):

- yield: 95.0% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- C5 degradation: 4.6%;

- C5 content: 81.2%.

EXAMPLE 18 (comparative)

885 g water and 2.1 g (21.8 mmol) methanesulfonic acid (CH ₃ -SO ₃ H) (first amount of organic acid) and 8.7 g (88.7 mmol) sulfuric acid (H ₂ SO ₄ ) ( the first amount of inorganic acid) (R ₁ = 0.13 mmol/g) was placed in a 2 L Brignole autoclave in the open air. Then 135 g of bagasse (2) obtained from previously crushed guayule plants (Parthenium argentatum) (sifted to below 2 mm) was added. Finally, 7.0 g (71.4 mmol) of sulfuric acid (H ₂ SO ₄ ) (the second amount of inorganic acid) was added, determined according to equation (1) and the following equations (R ₂ = 0.53 mmol/g; R _MINIMUM = 0.16 mmol/g): total added m _TOT = 181.9 mmol.

The first reaction mixture thus obtained was maintained under vigorous stirring (600 rpm) until it reached a temperature of 140°C in 45 minutes, whereby a second reaction mixture was obtained containing a first solid phase containing lignin and cellulose, and a first aqueous phase containing sugars derived from hemicellulose.

After cooling the autoclave to room temperature, these phases were separated by filtration.

The composition of the original biomass, determined as described above, was as follows: 47.0 wt.% cellulose, 20.2 wt.% hemicellulose, 26.8 wt.% lignin relative to the total weight of the original biomass. The rest consisted of organic acids, protein and non-protein nitrogen substances, lipids and mineral salts.

The first aqueous phase was analyzed as described above and the following results were obtained (shown in Table 6):

- yield: 79.4% (relative to the total amount of hemicellulose present in the original biomass);

- decomposition of C6: 0.0%;

- decomposition of C5: 1.5%;

- C5 content: 78.8%.

Table 1

Bagasse Hydrolysis Results (1)

Example m _{1
(mmol) m2
(mmol) R1
(mmol/g) R2
(mmol/g)} R _{MINIMUM
(mmol/g)} Exit (%) C6 decomposition (%) C5 decomposition (%) C5 content (%) 1 (compar.) CH ₃ -SO ₃ H (*) (111.3) - 0.13 0.00 0.82 80.3 0.0 0.7 79.4 2 (compar.) H ₂ SO ₄ (*) (109.1) - 0.12 0.00 0.00 69.1 1.7 3.2 72.6 3 (pic.) CH ₃ -SO ₃ H (*) (111.3) CH ₃ -SO ₃ H(**) (73.9) 0.13 0.55 1.37 95.0 0.0 4.6 80.5 7 (pic.) CH ₃ -SO ₃ H (*) (111.3) H ₂ SO ₄ (**) (72.4) 0.13 0.54 0.82 95.1 0.0 4.5 80.1

(*): moles of acid relative to the amount of water (G ₁ ) determined according to the equation (1) shown above;

(**): moles of acid relative to the amount of biomass (G ₂ ) determined according to the equation (1) shown above;

table 2

Results obtained from the hydrolysis of bagasse (2)

Example m _{1
(mmol) m2
(mmol) R1
(mmol/g) R2
(mmol/g)} R _{MINIMUM
(mmol/g)} Exit (%) C6 decomposition (%) C5 decomposition (%) C5 content (%) 4 (compar.) CH ₃ -SO ₃ H (*) (111.3) - 0.13 0.00 0.82 79.9 0.0 0.6 80.4 5 (compar.) H ₂ SO ₄ (*) (109.1) - 0.12 0.00 0.00 68.4 2.4 3.6 70.1 6 (pic.) CH ₃ -SO ₃ H (*) (111.3) CH ₃ -SO ₃ H(**) (73.9) 0.13 0.55 1.37 95.2 0.0 4.4 80.7 8 (pic.) CH ₃ -SO ₃ H (*) (111.3) H ₂ SO ₄ (**) (72.4) 0.13 0.54 0.82 95.4 0.0 4.5 80.3

(*): moles of acid relative to the amount of water (G ₁ ) determined according to the equation (1) shown above;

(**): moles of acid relative to the amount of biomass (G ₂ ) determined according to equation (1) shown above.

Table 3

Results obtained from the hydrolysis of bagasse (1) with varying amounts of H ₂ SO ₄

Example m _{1
(mmol) m2
(mmol) R1
(mmol/g) R2
(mmol/g)} R _{MINIMUM
(mmol/g)} Exit (%) C6 decomposition (%) C5 decomposition (%) C5 content (%) 7 (pic.) CH ₃ -SO ₃ H ^(*) (111.3) H ₂ SO ₄ ^(**) (72.4) 0.13 0.54 0.82 95.1 0.0 4.5 80.1 9 (compar.) CH ₃ -SO ₃ H ^(*) (111.3) _{H2SO4 (} ^**)
(flaw)
(30.6) 0.13 0.23 0.82 87.8 0.0 3.9 80.1 10 (comp.) CH ₃ -SO ₃ H ^(*) (111.3) H ₂ SO ₄ ^(**) (excess)
(112.2) 0.13 0.82 0.82 86.1 1.1 7.2 74.3

(*): moles of acid relative to the amount of water (G ₁ ) determined according to the equation (1) shown above;

(**): moles of acid relative to the amount of biomass (G ₂ ) determined according to equation (1) shown above.

Table 4

Results obtained from the hydrolysis of bagasse (2) with varying amounts of H ₂ SO ₄

Example m _{1
(mmol) m2
(mmol) R1
(mmol/g) R2
(mmol/g)} R _{MINIMUM
(mmol/g)} Exit (%) C6 decomposition (%) C5 decomposition (%) C5 content (%) 8 (pic.) CH ₃ -SO ₃ H ^(*) (111.3) H ₂ SO ₄ ^(**) (72.4) 0.13 0.54 0.82 95.4 0.0 4.5 80.3 11 (comp.) CH ₃ -SO ₃ H ^(*) (111.3) H ₂ SO ₄ ^(**) (deficiency)
(30.6) 0.13 0.23 0.82 84.7 0.0 3.9 80.5 12 (comp.) CH ₃ -SO ₃ H ^(*) (111.3) H ₂ SO ₄ ^(**) (excess)
(112.2) 0.13 0.82 0.82 86.3 1.1 4.3 71.3

(*): moles of acid relative to the amount of water (G ₁ ) determined according to the equation (1) shown above;

(**): moles of acid relative to the amount of biomass (G ₂ ) determined according to equation (1) shown above.

Table 5

Results obtained from the hydrolysis of bagasse (1) at various R _MINIMUM ratios (mmol/g) ^(*)

Example _{R1
(mmol/g) R2
(mmol/g)} R _{MINIMUM
(mmol/g)} Exit (%) C6 decomposition (%) C5 decomposition (%) C5 content (%) 13 (pic.) 0.13 0.53 0.41 96.0 0.0 4.6 81.2 14 (pic.) 0.13 0.53 0.25 95.4 0.0 4.2 79.8 15 (comp.) 0.13 0.53 0.16 81.4 0.0 1.1 79.2

(*): R _MINIMUM (mmol/g) defines the ratio between the used moles of organic acid (CH ₃ -SO ₃ H) (mmol) and biomass (G ₂ ); in order to obtain the total number of moles of acid m _TOT according to the equation (1) shown above, the inorganic acid H ₂ SO ₄ was used.

Table 6

Results obtained from the hydrolysis of bagasse (2) at different R _MINIMUM ratios (mmol/g) ^(*)

Example _{R1
(mmol/g) R2
(mmol/g)} R _{MINIMUM
(mmol/g)} Exit (%) C6 decomposition (%) C5 decomposition (%) C5 content (%) 16 (pic.) 0.13 0.53 0.41 95.2 0.0 4.3 80.7 17 (pic.) 0.13 0.53 0.25 95.0 0.0 4.6 81.2 18 (comp.) 0.13 0.53 0.16 79.4 0.0 1.5 78.8

(*): R _MINIMUM (mmol/g) defines the ratio between the used moles of organic acid (CH ₃ -SO ₃ H) (mmol) and biomass (G ₂ ); in order to obtain the total number of moles of acid m _TOT according to the equation (1) shown above, the inorganic acid H ₂ SO ₄ was used.

The data in Table 1 [bagasse (1)] shows that:

- Example 1 (comparative), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used in relation to the amount of water used (G ₁ ), without further adding the amount of m ₂ (mmol) organic or inorganic acid, determined according to equation (1) and the following equations, has a low yield of sugars [Yield (%)] (80.3%); in addition, from the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.00 mmol/g and R _MINIMUM = 0.82 mmol/g, it becomes clear that the value of R ₂ does not correspond to the present invention;

- Example 2 (comparative), in which the amount m ₁ (mmol) of sulfuric acid (H ₂ SO ₄ ) was used in relation to the amount of water used (G ₁ ), without further adding a certain amount m ₂ (mmol) of an organic or inorganic acid , according to equation (1) and the following equations, has a low yield of sugars [Yield (%)] (69.1%), lower than in Example 1 (comparative); moreover, with regard to Example 1 (comparative), hydroxymethylfurfural (HMF) is formed in small amounts (decomposition rate is 1.7%) along with a marked increase in decomposition to furfural (F) (decomposition rate is 3.2%); in addition, from the study of the parameters R ₁ =0.12 mmol/g, R ₂ = 0.00 mmol/g and R _MINIMUM = 0.00 mmol/g, it becomes clear that the values of R ₂ and R _MINIMUM do not correspond to the present invention;

- Example 3 (invention), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G ₁ ) and the amount m ₂ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of biomass used (G ₂ ), determined in accordance with equation (1) and the following equations, has a high yield of sugars [Yield (%)] (95.0%); also no formation of hydroxymethylfurfural (HMF) is observed (the degree of decomposition is 0.0%); in addition, from the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.55 mmol/g and R _MINIMUM =1.37 mmol/g, it becomes clear that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention;

Example 7 (invention), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G1), and the amount m ₂ (mmol) of sulfuric acid (H ₂ SO ₄ ) was used with respect to the amount of biomass used (G2) determined in accordance with equation (1) and the following equations, has a high yield of sugars [yield (%)] (95.1%), comparable with the yield in example 3 (invention); finally, decomposition to furfural (F) is observed (decomposition rate equal to 4.5%), comparable with the decomposition obtained in Example 3 (invention), thus confirming that the use of sulfuric acid (H ₂ SO ₄ ) does not have a negative effects on sugar yield or decomposition to furfural; in addition, from the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.54 mmol/g and R _MINIMUM =0.82 mmol/g, it becomes clear that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention.

The data in Table 2 ((bagasse (2)) shows that:

- Example 4 (comparative), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water G ₁ used, without additionally adding a certain amount of m ₂ (mmol) organic or inorganic acid, according to equation (1) and the following equations, has a low yield of sugars [Yield (%)] (79.9%); in addition, from the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.00 mmol/g and R _MINIMUM = 0.82 mmol/g, it becomes clear that the value of R ₂ does not correspond to the present invention;

- Example 5 (comparative), in which the amount m ₁ (mmol) of sulfuric acid (H ₂ SO ₄ ) was used in relation to the amount of water used (G ₁ ), without additionally adding a certain amount of m ₂ (mmol) organic or inorganic acid , according to equation (1) and the following equations, has a low yield of sugars [Yield (%)] (68.4%) and lower than in Example 5 (comparative); in addition, with regard to Example 5 (comparative), hydroxymethylfurfural (HMF) is formed in significant amounts (decomposition rate is 2.4%) along with a marked increase in the decomposition of furfural (F) (decomposition rate is 3.6%); in addition, from the study of the parameters R ₁ =0.12 mmol/g, R ₂ =0.00 mmol/g and R _MINIMUM = 0.00 mmol/g, it becomes clear that the values of R ₂ and R _MINIMUM do not correspond to the present invention;

- Example 6 (invention), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G ₁ ) and the amount m ₂ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H ) was used relative to the amount of biomass used (G ₂ ) determined according to equation (1) and the following equations, has a high yield of sugars [Yield (%)] (95.2%); in addition, no formation of hydroxymethylfurfural (HMF) is observed (decomposition rate is 0.0%); in addition, from the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.55 mmol/g and R _MINIMUM = 1.37 mmol/g, it becomes clear that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention;

- Example 8 (invention), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G ₁ ), and the amount m ₂ (mmol) of sulfuric acid (H ₂ SO ₄ ) with respect to the amount of biomass used (G2) determined according to equation (1) and the following equations, has a high yield of sugars [Yield (%)] (95.4%), comparable to that of Example 6 (invention); finally, decomposition to furfural (F) is observed (decomposition rate equal to 4.5%), comparable to that in Example 6 (invention), thus confirming that the use of sulfuric acid (H ₂ SO ₄ ) does not adversely affect neither on the release of sugar, nor on decomposition to furfural; in addition, from the study of the parameters R ₁ = 0.13 mmol/g, R2 = 0.54 mmol/g and R _MINIMUM = 0.82 mmol/g, it becomes clear that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention .

The data shown in Table 3 [bagasse (1)] shows that:

- Example 7 (invention), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water G ₁ , and the amount m ₂ (mmol) of sulfuric acid (H ₂ SO ₄ ) was used with respect to the amount of biomass used (G ₂ ) determined according to equation (1) and the following equations, has a high yield of sugars [Yield (%)] (95.1%); in addition, no formation of hydroxymethylfurfural (HMF) is observed (decomposition rate is 0.0%); in addition, from the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.54 mmol/g and R _MINIMUM =0.82 mmol/g, it becomes clear that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention;

- Example 9 (comparative), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G ₁ ) and the amount m ₂ (mmol) of sulfuric acid (H ₂ SO ₄ ) in relation to the amount of biomass used (G ₂ ) is lower than determined in accordance with equation (1) and the following equations, has a lower yield of sugars [Yield (%)] (87.8%) than in example 7 (invention ) ; in addition, from the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.23 mmol/g and R _MINIMUM = 0.82 mmol/g, it becomes clear that the value of R ₂ does not correspond to the present invention;

- Example 10 (comparative), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G ₁ ) and the amount m ₂ (mmol) of sulfuric acid (H ₂ SO ₄ ) in relation to the amount of biomass used (G ₂ ) is higher than determined in accordance with equation (1) and the following equations, has a lower yield of sugars [yield (%)] (86.1%) than in example 7 (invention) ; there is also a noticeable increase in decomposition to furfural (F) (decomposition rate is 7.2%); in addition, studying the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.82 mmol/g and R _MINIMUM = 0.82 mmol/g, it is clear that the value of R ₂ does not correspond to the present invention.

The data in Table 4 [bagasse (2)] shows that:

- Example 8 (invention), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G ₁ ) and the amount m ₂ (mmol) of sulfuric acid (H ₂ SO ₄ ) relative to the amount of biomass used (G ₂ ) determined in accordance with equation (1) and the following equations, has a high yield of sugars [Yield (%)] (95.4%); in addition, no formation of hydroxymethylfurfural (HMF) is observed (decomposition rate is 0.0%); in addition, the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.54 mmol/g and R _MINIMUM = 0.82 mmol/g shows that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention;

- Example 11 (comparative), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G ₁ ) and the amount m ₂ (mmol) of sulfuric acid (H ₂ SO ₄ ) in relation to the amount of biomass used (G ₂ ) lower than determined in accordance with equation (1) and the following equations, has a lower yield of sugars [Yield (%)] 84.7%) than in example 8 (invention); in addition, the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.23 mmol/g and R _MINIMUM = 0.82 mmol/g shows that the value of R ₂ does not correspond to the present invention;

- Example 12 (comparative), in which the amount m ₁ (mmol) of methanesulfonic acid (CH ₃ -SO ₃ H) was used relative to the amount of water used (G ₁ ) and the amount m ₂ (mmol) of sulfuric acid (H ₂ SO ₄ ), in relation to the amount of biomass used, G ₂ is higher than determined in accordance with equation (1) and the following equations, has a lower yield of sugars (yield (%) 86.3%) than in example 8 (invention); there is also a marked increase in decomposition to furfural (F) (decomposition rate between 7.4%); in addition, the study of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.82 mmol/g and R _MINIMUM = 0.82 mmol/g shows that the R2 value does not correspond to the present invention.

The data in Table 5 [bagasse (1)] shows that:

- Example 13 (invention), which used methanesulfonic acid (CH ₃ -SO ₃ H) and sulfuric acid (H ₂ SO ₄ ), has a high yield of sugars [yield (%)] (95.1%) and decomposition to furfural (F) (the degree of decomposition is up to 4.6%) comparable to that obtained in examples 3, 6, 7 and 8 (invention), thus confirming that the use of sulfuric acid (H ₂ SO ₄ ) does not adversely affect either yield of sugar, nor on decomposition to furfural; in particular, the analysis of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.53 mmol/g and R _MINIMUM = 0.41 mmol/g shows that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention;

- Example 14 (invention), which used methanesulfonic acid (CH ₃ -SO ₃ H) and sulfuric acid (H ₂ SO ₄ ), has a high yield of sugars [yield (%)] (95.4%) and decomposition to furfural (F) (decomposition rate is up to 4.2%) comparable to those obtained in examples 3, 6, 7 and 8 (invention), thus confirming that the use of sulfuric acid (H ₂ SO ₄ ) does not adversely affect either yield of sugar, nor on decomposition to furfural; in particular, analysis of the parameters R1 = 0.13 mmol/g, R ₂ = 0.53 mmol/g and R _MINIMUM = 0.25 mmol/g shows that the values of R ₁ , R ₂ and R _MINIMUM are in accordance with the present invention;

- Example 15 (comparative), which used methanesulfonic acid (CH ₃ -SO ₃ H) and sulfuric acid (H ₂ SO ₄ ), has a low yield of sugars [Yield (%)] (81.4%); in particular, the study of the parameters R ₁ = 0.13 mmol/g, R2 = 0.53 mmol/g and R _MINIMUM = 0.16 mmol/g shows that the R _MINIMUM value does not correspond to the present invention (i.e., insufficient amount organic acid is present).

The data in Table 6 [bagasse (2)] shows that:

- Example 16 (invention), which used methanesulfonic acid (CH ₃ -SO ₃ H) and sulfuric acid (H ₂ SO ₄ ), has a high yield of sugars [yield (%)] (95.2%) and decomposition to furfural (F) (the degree of decomposition is up to 4.3%) comparable to those obtained in examples 3, 6, 7 and 8 (invention), thus confirming that the use of sulfuric acid (H ₂ SO ₄ ) does not adversely affect either yield of sugar, nor on decomposition to furfural; in particular, the analysis of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.53 mmol/g and R _MINIMUM = 0.41 mmol/g shows that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention;

- Example 17 (invention), which used methanesulfonic acid (CH ₃ -SO ₃ H) and sulfuric acid (H ₂ SO ₄ ), has a high yield of sugars (yield (%) 95.0%) and decomposition to furfural (F ) (decomposition from 4.6%), comparable to that obtained in examples 3, 6, 7 and 8 (invention), thus confirming that the use of sulfuric acid (H ₂ SO ₄ ) does not adversely affect either the yield of sugar , nor on decomposition to furfural; in particular, the analysis of the parameters R ₁ = 0.13 mmol/g, R ₂ = 0.53 mmol/g and R _MINIMUM = 0.25 mmol/g shows that the values of R ₁ , R ₂ and R _MINIMUM correspond to the present invention;

- Example 18 (comparative), which used methanesulfonic acid (CH ₃ -SO ₃ H) and sulfuric acid (H ₂ SO ₄ ), has a low yield of sugars [Yield (%)] (79.4%); in particular, the results of the study of parameters R ₁ = 0.13 mmol/g, R ₂ = 0.53 mmol/g and R _MINIMUM = 0.16 mmol/g show that the value of R _MINIMUM does not correspond to the present invention (i.e. insufficient amount of organic acid is present).

It should also be noted that the use of bagasse (1) or bagasse (2) gives comparable results, confirming the fact that the bagasse process is not relevant to the purposes of the present invention.

Claims (45)

1. A method for obtaining sugars from biomass obtained from guayule plants, which includes the following steps: (a) contacting biomass from guayule plants G ₂ , g, with water G ₁ , g, and at least one organic acid and optionally at least one inorganic acid in a reactor to obtain a first reaction mixture; (b) heating the reactor to a temperature of 100°C to 180°C for 20 minutes to 2 hours to obtain a second reaction mixture containing a first solid phase and a first aqueous phase; (c) optionally maintaining said second reaction mixture containing the first solid phase and the first aqueous phase at the above temperature for 30 seconds to 1 hour, (d) withdrawing said second reaction mixture containing sugars, where at least one sugar has 5 C ₅ carbon atoms and optionally at least one sugar has 6 C ₆ carbon atoms, from said reactor; wherein in step (a) said at least one organic acid and said at least one inorganic acid, optionally present, are used in such amounts that the total number of moles of said at least one organic acid and said at least one inorganic acid , optionally present, m _TOT contained in the specified mixture, are calculated in accordance with the following equation (1): m _TOT = m ₁ + m ₂ (1), where m ₁ and m ₂ are defined according to the following equations (2) and (3) respectively: m ₁ \u003d R ₁ G ₁ (2), m ₂ \u003d R ₂ G ₂ (3), wherein: - R ₁ , mmol/g, is the ratio between the first amount of said at least one organic acid, mmol, and the first amount of said at least one inorganic acid, mmol, optionally present, and the amount of water G ₁ used, g, a R ₁ is from 0.06 mmol/g to 0.25 mmol/g, and the specified first amount of at least one organic acid, mmol, and the specified first amount of at least one inorganic acid, mmol, are optionally present depending on the amount water G ₁ , g; - R ₂ , mmol/g, is: - in the absence of said at least one inorganic acid, the ratio between the second amount of at least one organic acid, mmol, and the amount of biomass used G ₂ , g; or - in the presence of said at least one inorganic acid, the ratio between the sum of said second amount of at least one organic acid, mmol, and the second amount of said at least one inorganic acid, mmol, and the amount of biomass G ₂ used, g; or - in the presence of the specified second amount of at least one inorganic acid, mmol, and in the absence of the specified second amount of at least one organic acid, mmol, the ratio between the specified second amount of at least one inorganic acid, mmol, and the amount of biomass used G ₂ , G; where the specified second amount of at least one organic acid, mmol, and the specified second amount of at least one inorganic acid, mmol, depends on the amount of biomass G ₂ , g; R ₂ is from 0.90R mmol/g to 1.10R mmol/g, where R is determined using the following algorithm (4), where the specified algorithm (4) is performed using the following elementary operations: (i) preparing a volume V, l, of an aqueous solution of said at least one organic acid and said at least a first amount of at least one inorganic acid, mmol, optionally present, wherein said aqueous solution has a pH of ₁ below 7; (ii) adding the amount of biomass Q, g, dried at 120°C for 15 hours, to the aqueous solution obtained in step (i), and the specified amount of biomass is less than or equal to 60 wt.% in relation to the total mass of the resulting mixture; (iii) measuring the pH of the mixture obtained in step (ii), where said pH is referred to below as pH ₂ ; (iv) determination of R according to the following algorithm (4): R \u003d (10 ^-pH1 - 10 ^-pH2 ) 1000 V / Q (4), where pH ₁ , pH ₂ , V and Q have the same values as above, and where the above elementary operations are carried out at room temperature; provided that said at least one organic acid is present in such an amount that the ratio R _MINIMUM, mmol/g, is determined in accordance with the following equation (5): R _MINIMUM = m _{ORGANIC ACID} / G ₂ (5), where m _{ORGANIC ACID} is the number of mmol of organic acid present and G ₂ has the same meaning as above, equal to above or equal to 0.20 mmol/g, and if indicated, at least one inorganic acid is present and the specified mmol of organic acid m _{ORGANOIC ACID} is present in an amount less than the sum of two amounts of acid, i.e. the sum of the amount of inorganic acid, mmol, and the amount of organic acid, mmol, and this sum corresponds to the total amount m _TOT , mmol, moles, as defined in equation (1) above. 2. The method according to claim 1, where R ₁ is from 0.09 mmol/g to 0.18 mmol/g. 3. The method according to claim 1 or 2, where R ₂ is from 0.95R mmol/g to 1.05R mmol/g. 4. The method according to any one of the preceding claims, wherein said aqueous solution in step (i) has a pH of ₁ from 0.7 to 3. 5. The method according to any of the preceding paragraphs, where in step (ii) said amount of biomass is from 2 to 40 wt.% in relation to the total mass of the resulting mixture. 6. The method according to any one of the preceding claims, wherein G ₂ in equation (5) is greater than or equal to 0.25 mmol/g. 7. The method according to any one of the preceding claims, wherein said biomass obtained from guayule plants is bagasse obtained from extraction methods to which said guayule plants are subjected. 8. The method according to any of the previous paragraphs, where the specified biomass is subjected to preliminary grinding before bringing it into contact with water and with the specified at least one organic acid and optionally at least one inorganic acid; preferably said biomass is crushed to obtain particles with a diameter of 0.1 mm to 10 mm, more preferably 0.5 to 4 mm, even more preferably less than 2 mm. 9. Process according to any of the preceding claims, wherein said at least one organic acid is selected from alkyl sulfonic acids of general formula (I): R-SO ₃ H (I), where R represents a linear or branched C ₁ -C ₆ preferably C ₁ -C ₃ alkyl group; preferably it is methanesulfonic acid CH ₃ -SO ₃ H. 10. The method according to any of the preceding paragraphs, where the specified at least one inorganic acid is selected from strong inorganic acids such as hydrochloric acid HCl, nitric acid HNO ₃ , sulfuric acid H ₂ SO ₄ or mixtures thereof; preferably sulfuric acid H ₂ SO ₄ . 11. The method according to any of the previous paragraphs, where: in step (b) the reactor is heated to a temperature of 130°C to 150°C for 20 minutes to 2 hours, preferably 40 minutes to 1 hour; and in step (c) holding said second reaction mixture at the above temperature for 5 minutes to 20 minutes. 12. The method according to any of the previous paragraphs, where: - the specified biomass is present in the specified first reaction mixture in an amount of from 1 wt.% to 60 wt.%, preferably from 5 wt.% to 45 wt.%, even more preferably from 10 wt.% to 30 wt.% relative to the total mass said first reaction mixture; and/or - said reactor is selected from slurry reactors with continuous supply of biomass, where CSTR is a continuous reactor with mechanical agitation; and/or said first solid phase comprises lignin and cellulose and said first aqueous phase comprises at least one sugar having 5 carbon atoms C ₅ and optionally at least one sugar having 6 carbon atoms C ₆ and said at least one organic an acid, and optionally said at least one inorganic acid. 13. A method according to any one of the preceding claims, wherein said guayule plants are of the species Parthenium argentatum.