BIOMASS

FIELD OF THE INVENTION

The present invention relates generally to the field of biorefinery, and more specifically to the field of processing of lignocellulosic biomass into valuable components that can be used in downstream processing. The present invention relates in particular to a process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, and to the use of such components in the production of chemicals, such as fuels, polymers, bulk or fine chemicals, pharmaceuticals, antimicrobial agents, etc. or in pulp and paper industry.

BACKGROUND OF THE INVENTION

Biorefinery and biomass will play an increasingly crucial role over the coming decades.

Biorefinery is a refinery that converts biomass to energy and other beneficial bioproducts such as chemicals. It involves the sustainable processing of biomass into a spectrum of bio-based products such as food, feed, chemicals, materials, and bioenergy including biofuels, power and/or heat. As refineries, biorefineries can provide multiple chemicals by recovering from an initial raw material, i.e. the biomass, multiple intermediates that can be further converted into value-added products. For instance, the conversion of biomass to different forms of energy, has received growing attention as a mean of replacing energy and other end-products derived from fossil raw materials. In addition, biomass is considered a major renewable source for bulk chemicals and materials.

Especially lignocellulosic biomass, as one of the most abundant sources of biomass, can be perceived as an ideal feedstock for numerous biorefining processing technologies due to its low cost, abundance and widespread availability. Lignocellulosic biomass primarily consists of three polymeric components: cellulose (C ₆ -sugars), hemicellulose (mainly Cs-sugars) and lignin. Cellulose is a polysaccharide of glucose monomers linked by b-1 ,4 glucosidic bonds, while hemicellulose is a polysaccharide of mixed composition and structure, containing a large proportion of pentose sugars linked by b-1 ,4 bonds. Lignin is a very complex molecule with phenylpropane units linked in a three-dimensional structure. Lignocellulosic plant materials also contain extractives, which represent a minor fraction (typically between 5% and 15%). Extractives contain large numbers of lipophilic and hydrophilic constituents.

The rigid matrix of intertwined cellulose, hemicellulose and lignin polymers present in lignocellulosic biomass complicates the isolation and recovery of valuable components thereof, and the processing thereof towards fuels and chemicals. A key challenge in the processing of lignocellulosic biomass therefore is to find processes that allow for the most complete and efficient utilization of the main constituents.

In this context, especially the valorization of lignin in the frame of biomass fractionation is a challenging task in part due to lignin’s recalcitrant, irregular and complex polymeric structure, which has severely complicated the development of controlled methods for recovering lignin and derivatives thereof for the production of fine chemicals. Another major obstacle in the valorization of lignin is lignin’s strong tendency towards irreversible re-polymerisation and degradation. Lignin is generally present in lignocellulosic biomass in an amount of about 15 to 30% by weight. As a biopolymer, lignin is unusual because of its heterogeneity and lack of a defined primary structure. Moreover, various lignins differ structurally depending on biomass source and subsequent processing, but one common feature is a backbone consisting of various substituted phenylpropane units that are bound to each other via aryl ether or carbon-carbon linkages. They are typically substituted with methoxyl groups and the phenolic and aliphatic hydroxyl groups provide sites for e.g. further functionalization.

Strategies were reported in the prior art for obtaining depolymerized lignin, i.e. lignin degraded into small units or molecules that may be further processed. Depolymerized lignin can for instance be obtained by deployment of pretreatment methods, such as the kraft and organosolv methods. Such pretreatment methods involve a chemical treatment of the biomass. However, such pretreatment methods have the major disadvantage that they lead to lignin components of which the molecular structure is significantly altered with respect to native lignin, inevitably limiting their valorization.

For instance, certain processes rely on the use of a chemically pre-treated and pre-isloated lignin as substrate for subsequent depolymerization. An example thereof is WO2015/199608, which discloses method for the depolymerization of lignin starting from pre-isolated lignin fractions as substrate. During a first step lignins obtained from different sources such as e.g. black liquor, red liquor, Kraft lignin, sulfonated lignin, precipitated lignin, filtrated lignin, acetosolv or organosolv lignin, are depolymerized via hydrothermal treatment in an aqueous solution containing a sulphur-based reducing agent. The disclosed process thus relies on the depolymerisation of chemically pre-treated lignin. The output of such a process is an aqueous solution of lignin, possessing a lower molecular weight compared to the initial material. During a second step, the depolymerized lignin can then undergo esterification to increase its lipophilicity, followed by mixing with an organic carrier and hydrocracking or catalytic cracking to give a final product.

Another example of a process, wherein chemically pre-treated lignin is subjected to depolymerisation thereof is given in WO 2017/174207. This document discloses a process comprising a series of consecutive steps for the production of functionalized lignin derivatives from lignocellulosic biomass. This document discloses the step of subjecting lignocellulosic material to pulping. The pulping method adopted can be any existing pulping method such as e.g. Kraft pulping, sulfite pulping, soda pulping, organosolv pulping, etc. After the pulping treatment, pulp is separated from the liquid process stream(s), lignin-derived components are isolated from the liquid process stream(s) and are depolymerised by subjecting these to thermal decomposition or chemical decomposition, e.g. by means of oxidative cracking with oxidizing agents and homo/heterogeneous catalysts; reductive cracking with H2 and heterogeneous catalysts; enzymatic decomposition; photooxidation; treatment in ionic liquids.

Another technique involves catalytic organosolv fractionation. This technique allows to simultaneously fractionate lignocellulose into its main components and to treat lignin by disruption of the polymeric network, resulting in the production of phenolic monomers and oligomers. WO 2015/080660 for instance discloses a method for the depolymerization of lignin from biomass, involving the use of precious metal catalysts such as palladium-based catalysts, and a mixture of organic solvent and water. Another example thereof is given in Van den Bosch et al. (2015: Energy & Environmental Science, Vol. 8, pp. 1748-1763) which disclose a process for the depolymerization of lignin from biomass, wherein pressurized hydrogen gas and heterogeneous redox catalysts (e.g. Ru/C) are applied to achieve depolymerization of lignin. However, catalytic organosolv fractionation typically involves the use of rare and expensive precious metal catalyst, including metals such as ruthenium, platinum, rhodium and palladium, and requires high pressures of hydrogen gas. The latter constitutes an important limitation for scaling up such prior art processes. Catalysis based processes such as those mentioned above, have several drawbacks including high costs of precious metals catalysts, expensive downstream operations for catalyst recovery, and safety risks related to the use of high pressures of hydrogen gas.

Overall, existing strategies present some major drawbacks. Many of the prior art methods for treating lignocellulosic biomass and for producing lignin components involve for instance multiple steps, high temperatures and pressure and consume a lot of reagents, including expensive reagents such as hydrogen gas. Methods involving chemically pretreated lignin as substrate for depolymerization have the drawback that they may alter the molecular structure of the lignin. Catalyst based methods, such as catalytic organosolv fractionation, in addition often involve the use of precious metal catalysts, which render these processes cost-inefficient and less economically viable. Furthermore, the use of catalytic systems creates the need for catalyst recovery and separation thereof from the reaction components, often leading to choosing strategies that limit the catalytic performance and/or further increase the processing costs, such as the use of a catalyst baskets or expensive catalyst recovery downstream operations.

Therefore, there remains an ongoing need in the art to provide processes for treating lignocellulosic biomass, and in particular to produce valuable components including lignin components, from lignocellulosic biomass, which overcome at least some of the drawbacks of the prior art processes.

It is therefore an object of the present invention to provide processes for treating lignocellulosic biomass, and in particular for producing, isolating and recovering valuable components, including lignin components, from such biomass, which overcomes at least some of the disadvantages of the prior art processes.

One object of the invention is to provide a process for producing lignin components from lignocellulosic biomass without using a catalyst.

It is another object of the present invention to provide a process for producing lignin components from lignocellulosic biomass, while at the same time keeping components derived from cellulose and/or hemicellulose available for further processing.

It is further an object of the present invention to provide a process for the producing lignin components from lignocellulosic biomass having an improved and/or tailored composition.

The present invention further aims to provide a process for producing lignin components from lignocellulosic biomass which is cost effective, easy to carry out, and more environmentally friendly. The invention also aims to provide a process for treating lignocellulosic biomass which is a more economically viable integrated biorefinery concept. The present invention further aims to provide a process wherein the number of operational steps is minimized. The invention also aims to provide a providing concomitant (simultaneous) lignocellulosic biomass fractionation and lignin depolymerization.

SUMMARY

It has now surprisingly been found that the above objectives can be attained either individually or in any combination by applying a process as disclosed herein for treating lignocellulosic biomass. The processes as disclosed herein are of particular relevance in the field of biorefinery. The present invention in particular relates to a process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said process involves a depolymerization or disruption of the polymeric structure of the lignin in the lignocellulosic biomass using a solvent-based approach and in the absence of a catalyst. The lignocellulosic biomass processed in accordance with the present invention is in particular provided as solid biomass.

Thus, according to a first aspect, the present invention provides a process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said process comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting said lignocellulosic biomass with a composition comprising a reducing agent, preferably a sulphur containing reducing agent, and a solvent and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers.

Preferably, a process is provided wherein the lignocellulosic biomass is not chemically treated prior to contacting with said composition.

In another embodiment, the invention provides a process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said process comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting said lignocellulosic biomass with a composition comprising a reducing agent, wherein said reducing agent is a sulphur containing reducing agent, and a solvent,

(i) wherein said solvent is an organic solvent, or

(ii) wherein said solvent is a mixture of an organic solvent and water, and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and wherein said lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition. Also preferably, a process is provided wherein the lignocellulosic biomass provided in step a) is mechanically treated prior to contacting with said composition to reduce the size of said biomass.

In certain embodiments, a process is provided wherein, when said solvent is a mixture of an organic solvent and water, said process comprises the step of obtaining saccharide components from said lignocellulosic biomass and isolating and recovering said saccharide components.

In another aspect, the invention provides lignin components comprising lignin monomers, lignin dimers and lignin oligomers obtained or obtainable from lignocellulosic biomass by a process as disclosed herein, wherein said lignin components comprise lignin monomers in an amount of at least 3% based on the total weight of the lignin components, and preferably unsaturated lignin monomers in an amount of at least 1%, preferably at least 3%, based on the total weight of the lignin components.

According to another aspect, the present invention provides saccharide components obtained or obtainable from lignocellulosic biomass by a process as disclosed herein, wherein said components comprise C5 and C6 saccharides at a weight ratio of C6 to C5 carbohydrates comprised between 20:1 to 1.2:1 , and for instance between 15:1 and 1.5:1 , or between 10:1 and 2: 1 .

According to another aspect, the present invention relates to various uses of lignin components and saccharide components as disclosed herein, for instance in the production of chemicals, such as bulk and fine chemicals, in the production of fuels, as additives, or in pulp and paper industry. Another application includes the use of lignin components, such as lignin oil, in the antimicrobial agents production.

The present invention thus provides a process wherein valuable components, and in particular lignin components, are provided directly from the lignocellulosic biomass, i.e. without needing to first isolate the lignin from the biomass. In accordance with the present invention, the lignocellulosic biomass is contacted as a solid biomass with the composition comprising the solvent and the reducing agent, and preferably the organic solvent and the sulphur containing reducing agent. The lignocellulosic biomass is not chemically treated prior to contacting it with said composition in step b).

The lignocellulosic biomass which is provided as the substrate in a process according to the invention is thus applied as raw material, meaning that the solid biomass has not undergone any chemical treatment or processing prior to being subjected to the process of the invention. It was surprisingly found by the Applicant that the treatment of raw lignocellulosic biomass in an organic solvent, possibly in combination with water, in presence of a sulphur-containing reducing agent, permits to obtain a direct depolymerization of native lignin concomitantly to lignocellulose fractionation. It is unexpected that present process allows to simultaneously obtain lignocellulosic biomass fractionation and lignin depolymerization, especially as the process of the invention is carried out in the absence of a catalyst. Furthermore, the present invention provides processes that advantageously provide for effective biomass delignifi cation and lignin depolymerization, providing high delignifi cation yields of the lignocellulosic biomass, and yielding lignin monomers, dimers and oligomers, while at the same time preserving saccharide components that are contained in the biomass for further isolation recovery and use.

Moreover, the present process advantageously does not involve the use of a catalyst, and avoids all drawbacks related to such use. In addition, a process according to the invention allows obtaining components derived from the lignocellulosic biomass with specific compositions, which facilitates their use in specific downstream applications. The processes according to the present invention are cost-effective, and easy to carry out, and may advantageously also be integrated into pulping processes.

The independent and dependent claims set out particular and preferred features of the invention. Features from the dependent claims may be combined with features of the independent or other dependent claims as appropriate.

The present invention will now be further described. In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

DETAILED DESCRIPTION OF THE FIGURES

Figure 1 shows MWD profiles of lignin oil obtained from certain experiments reported in example 5 that were carried out at different weight ratios Na ₂ S ₂ 0 ₄ :biomass.

Figure 2 shows the MWD profiles of lignin oil obtained from certain experiments reported in example 5 that were carried out under different reaction times.

Figure 3 shows the MWD profiles of lignin oil obtained from certain experiments reported in example 5 that were carried out at different initial nitrogen pressures.

Figure 4 shows the MWD profiles of lignin oil obtained from certain experiments reported in example 5 that were carried out using different solvent compositions. Figure 5 shows the MWD profiles of lignin oil obtained from certain experiments reported in example 5 that were carried out at different temperatures.

Figure 6 shows the MWD profiles of lignin oil obtained from certain experiments reported in example 5 that were carried out at different biomass concentrations.

Figure 7 shows the MWD profiles of lignin oil obtained from certain experiments reported in example 6 that were carried out on herbaceous or softwood biomass using a process of the invention.

Figure 8 shows the MWD profiles of lignin oil obtained from certain experiments reported in example 7 that were carried out using different agents.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise.

The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms "comprising", "comprises" and "comprised of" as used herein comprise the terms "consisting of", "consists" and "consists of".

The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

The term "about" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of and from the specified value, in particular variations of +/-10% or less, preferably +1-5% or less, more preferably +/- 1% or less, and still more preferably +/-0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier "about" refers is itself also specifically, and preferably, disclosed. As used throughout the present disclosure, the terms “weight %” or “% w/w” or “% by weight” are used interchangeably and refer to the weight concentration of a constituent, i.e. the weight of a constituent divided by the total weight of all constituents.

All references cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings of all references herein specifically referred to are incorporated by reference.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art.

Preferred statements (features) and embodiments of processes, products such as compositions and components, and uses of this invention are set herein below. Each statement and embodiment of the invention so defined may be combined with any other statement and/or embodiment unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features or statements indicated as being preferred or advantageous. Hereto, the present invention is in particular captured by any one or any combination of one or more of the below numbered aspects and embodiments 1 to 57, with any other statement and/or embodiment.

Statements

1. Process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said process comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting said lignocellulosic biomass with a composition comprising a reducing agent, preferably a sulphur containing reducing agent, and a solvent and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers.

2. Process according to statement 1 , wherein said reducing agent is a sulphur containing reducing agent.

3. Process according to statement 1 or 2, wherein said lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition.

4. Process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said process comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting said lignocellulosic biomass with a composition comprising a reducing agent, wherein said reducing agent is a sulphur containing reducing agent, and a solvent,

(i) wherein said solvent is an organic solvent, or

(ii) wherein said solvent is a mixture of an organic solvent and water, and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and wherein said lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition.

5. Process according to any one of statements 1 to 4, wherein the lignocellulosic biomass provided in step a) is mechanically treated prior to contacting with said composition to reduce the size of said biomass.

6. Process according to any one of statements 1 to 5, wherein said lignocellulosic biomass is provided in step a) in the form of particles or powder.

7. Process according to any one of statements 1 to 6, wherein said lignocellulosic biomass is provided in step a) in the form of particles or powder having a particle size of 10 cm or less, or of 5 cm or less, or of 2 cm or less, or of 1 cm or less or of 5 mm or less, or of 1 mm or less; or of 500 pm or less.

8. Process according to any one of statements 1 to 7, wherein the lignocellulosic biomass is wood. 9. Process according to any one of statements 1 to 8, wherein the lignocellulosic biomass is hardwood or softwood, and preferably is hardwood.

10. Process according to any one of statements 1 to 9, wherein said lignocellulosic biomass is hardwood that is provided in step a) in the form of saw dust or wood chips.

11. Process according to any one of statements 1 to 7, wherein the lignocellulosic biomass is herbaceous biomass material.

12 Process according to any of statements 1 to 3 and 5 to 11 , wherein the reducing agent is a borohydride, for instance selected from the group comprising sodium borohydride, potassium borohydride, and lithium borohydride.

13. Process according to any of statements 1 to 11, wherein the sulphur containing reducing agent is selected from the group comprising, and preferably consisting of, sodium or potassium dithionite, sodium or potassium sulfite, sodium or potassium thiosulfate, sodium or potassium metabisulfite, sodium or potassium sulfinate, thiourea oxide, thiourea dioxide, thiourea trioxide, sodium or potassium hydroxymethane sulfinate, sodium or potassium hydroxyethane sulfinate, sodium or potassium hydroxypropane sulfinate, sodium or potassium hydroxybutane sulfinate, thiophenol, and sulfur dioxide, or any combination thereof; and preferably is selected from the group comprising, and preferably consisting of, sodium dithionite, potassium dithionite, sodium sulfite, and potassium sulfite, sodium thiosulfate, or any combination thereof, and more preferably is selected from sodium dithionite (NaaSaCU), sodium thiosulfate (NaaSaCh) or sodium sulfite (NaaSCh).

14. Process according to any of statements 1 to 13, wherein the reducing agent, is applied at a concentration of between 1.5 and 40 g/L, and preferably at a concentration of between 3 and 25 g/L.

15. Process according to any of statements 1 to 11 and 13, wherein the sulphur containing reducing agent is applied at a concentration of between 1.5 and 40 g/L, and preferably at a concentration of between 3 and 25 g/L.

16. Process according to any of statements 1 to 15, wherein the reducing agent, is applied in an amount of 5 to 40 wt%, based on the total weight of said lignocellulosic biomass, and preferably in an amount of 6 to 35 wt% or of 7 to 30 wt%, or of 10 to 20 wt%, or of 10 to 17 wt%, based on the total weight of said lignocellulosic biomass.

17. Process according to any of statements 1 to 11 and 13 to 16, wherein the sulphur containing reducing agent is applied in an amount of 5 to 40 wt%, based on the total weight of said lignocellulosic biomass, and preferably in an amount of 6 to 35 wt% or of 7 to 30 wt%, or of 10 to 20 wt%, or of 10 to 17 wt%, based on the total weight of said lignocellulosic biomass.

18. Process according to any of statements 1 to 17, wherein said solvent is an organic solvent, preferably an alcohol, preferably a C1 to C10 alcohol, and even more preferably a C1 to C5 alcohol.

19. Process according to any of statements 1 to 17, wherein said solvent is an organic solvent, and said organic solvent is an alcohol, preferably a C1 to C10 alcohol, and even more preferably a C1 to C5 alcohol.

20. Process according to any of statements 1 to 19, wherein said solvent is an organic solvent, and said organic solvent is an alcohol selected form the group comprising methanol, ethanol, 1-propanol, 2-propanol and butanol, and preferably is methanol or butanol or 2-propanol (isopropanol).

21. Process according to any of statements 1 to 17, wherein said solvent is a mixture of an organic solvent and water, preferably a mixture of an alcohol and water, more preferably mixture of a C1 to C10 alcohol and water, even more preferably a mixture of a C1 to C5 alcohol and water.

22. Process according to any of statements 4 to 17 and 21, wherein said solvent is a mixture of an organic solvent and water, and wherein said mixture of an organic solvent and water is a mixture of an alcohol and water, more preferably mixture of a C1 to C10 alcohol and water, even more preferably a mixture of a C1 to C5 alcohol and water.

23. Process according to any of statements 1 to 17 and 21-22, wherein said solvent is a mixture of an alcohol and water, wherein said alcohol is selected form the group comprising methanol, ethanol, 1-propanol, 2-propanol and butanol, and preferably wherein said alcohol is methanol or butanol or 2-propanol (isopropanol).

24. Process according to any of statements 4 to 17 and 21-23, wherein said water is applied in said mixture of organic solvent and water at a volume ratio of water to organic solvent which is comprised between 10:1 and 1 :10 such as between 7:1 and 1 :1 or between 5:1 and 1:1, or between 3:1 and 1 :1 or between 2:1 and 1 :1 , or between 1:1 and 1:10, or between 1:1 and 1:7, or between 1.1 and 1:5, or between 1:1 and 1 :3, or between 1 :1 and 1:2.

25. Process according to any of statements 4 to 24, wherein said process comprises the step of obtaining saccharide components from said lignocellulosic biomass and isolating and recovering said saccharide components. 26. Process according to any of statements 1 to 20, wherein said lignocellulosic biomass is contacted with a composition comprising, and for instance consisting of,

(i) a reducing agent, preferably a sulphur containing reducing agent, more preferably sodium dithionite, and ii) an organic solvent, preferably a solvent as defined herein, preferably butanol.

27. Process according to any of statements 1 to 17, and 21-25, wherein said lignocellulosic biomass is contacted with a composition comprising, and for instance consisting of, i) a reducing agent, preferably a sulphur containing reducing agent, more preferably sodium dithionite, ii) an organic solvent, preferably a solvent as defined herein, preferably butanol, and iii) water, wherein the volume ratio of water to said organic solvent is comprised between 10:1 and 1 :10 such as between 7:1 and 1 :1 or between 5:1 and 1 :1 , or between 3:1 and 1 :1 or between 2:1 and 1 :1 , or between 1:1 and 1 :10, or between 1 :1 and 1:7, or between 1.1 and 1 :5, or between 1:1 and 1:3, or between 1:1 and 1:2.

28. Process according to any of statements 1 to 17, and 21-25 and 27, wherein said lignocellulosic biomass is contacted with a composition comprising, and for instance consisting of, i) a sulphur containing reducing agent, more preferably a sulphur containing reducing agent as defined herein, more preferably sodium dithionite, ii) an organic solvent, preferably an organic solvent as defined herein, preferably butanol or methanol or isopropanol, more preferably butanol, and iii) water, wherein the volume ratio of water to said organic solvent is comprised between 10:1 and 1 :10 such as between 7:1 and 1 :1 or between 5:1 and 1 :1 , or between 3:1 and 1 :1 or between 2:1 and 1 :1 , or between 1:1 and 1 :10, or between 1 :1 and 1:7, or between 1.1 and 1 :5, or between 1:1 and 1:3, or between 1 :1 and 1 :2.

29. Process according to any of statements 1 to 28, wherein said composition is prepared by providing said reducing agent, preferably said sulphur containing reducing agent, in a solid state and dissolving said reducing agent, preferably said sulphur reducing agent in said solvent. 30. Process according to any of statements 1 to 29, wherein said lignocellulosic biomass is contacted with said composition at a temperature comprised between 175°C and 250°C, or between 175°C and 230°C and preferably comprised between 180 °C and 230 °C, or between 180°C and 250°C, and for instance comprised between 190°C and 230°C or between 190 °C and 220 °C or between 190°C and 210°C, or between 195°C and 210°C, or between 200°C and 225°C.

31. Process according to any of statements 1 to 30, wherein said lignocellulosic biomass is contacted with said composition for 0.75 hour or longer; such as for 1 hour or longer, such as for 3 hours or longer, for 6 hours or longer, for 12 hours or longer, and is preferably performed in an inert atmosphere or in an atmosphere containing inert gas.

32. Process according to any of statements 1 to 31, wherein said lignocellulosic biomass is contacted with said composition in the absence of a catalyst, such as in the absence of a metal catalyst, a transition metal catalyst, and/or a precious metal catalyst.

33. Process according to any of statements 1 to 32 wherein said lignocellulosic biomass is contacted with said composition in the absence of hydrogen gas.

34. Process according to any of statements 1 to 33, wherein the composition as applied in step b) is prepared by providing said reducing agent, preferably a sulphur containing reducing agent in a solid state and dissolving said sulfur reducing agent in said solvent.

35. Process according to any one of statements 1 to 34, wherein said lignin monomers comprise unsaturated and/or saturated lignin monomers having the formula (I) wherein R ¹ and R ³ are independently H or OCH ₃ , wherein R ² is selected from the group consisting of H, OH, CH ₃ , CH ₂ OH, CHO, COCH ₃ , CH ₂ CH ₃ , (CH ₂ ) ₂ OH, CH ₂ CHO, CH ₂ COCH ₃ , (CH ₂ ) ₂ COCH ₃ , (CH ₂ ) ₂ CH ₃ , CH ₂ CHCH ₂ , (CH) ₂ CH ₃ , (CH ₂ ) ₃ OH,

CH ₂ (CH) ₂ OH, (CH) ₂ CH ₂ OH, (CH) ₂ CHO, (CH ₂ ) ₂ CHO and CO(CH ₂ ) ₂ CH ₃ , and wherein R ⁴ is OH or OCH ₃ or OCH ₂ CH ₃ . 36. Process according to any one of statements 1 to 35 wherein the delignification yield (Y _D ) of said lignocellulosic biomass is at least 48%, preferably at least 50%, preferably at least 55%, preferably at least 60%, and for instance at least 75%; 80%; 85%; 90%; 95%; 98%, 99%, or 100%, wherein said delignification yield (Y _D ) is expressed as :

YD (in %) = WLC/WAIL wherein:

WLC is the total weight of lignin components

WAIL is the total weight of acid insoluble lignin in said lignocellulosic biomass

37. Process according to any one of statements 1 to 36, wherein the lignin monomer yield (Y _M ) of said lignocellulosic biomass is at least 3%, and preferably at least 5%, 6%, 7%, 10%, 12%, 15%; 20%; or 25%, and wherein said lignin monomer yield (Y _M ) is expressed as :

Y _M (in %) = WLM/WAIL wherein

WLM is the total weight of lignin monomers

WAIL is the total weight of acid insoluble lignin in said lignocellulosic biomass

38. Process according to any one of statements 1 to 37, wherein the yield of saturated lignin monomers (YMS) of said lignocellulosic biomass is at least 1%, and for instance of at least 3%; 5%; 7%; 10%; 12%; 15%; 20%; 25%, and wherein said saturated lignin monomer yield (YMS) is expressed as :

YMS (in %) = WLMS/WAIL wherein

WLMS is the total weight of saturated lignin monomers

WAIL is the total weight of acid insoluble lignin in said lignocellulosic biomass

39. Process according to any one of statements 1 to 38, wherein the yield of unsaturated lignin monomers (YMUS) of said lignocellulosic biomass, is at least 1%, and preferably at least 3%; 5%; 7%; 10%; 12%; 15%; 20%; 25%, and wherein said unsaturated lignin monomer yield (YMUS) is expressed as :

YMUS (in %) = WLMUS/WAIL wherein

WLMUS is the total weight of unsaturated lignin monomers WAIL is the total weight of acid insoluble lignin in said lignocellulosic biomass

40. Process according to any one of statements 1 to 39, wherein said lignin components have a weight average molecular weight (Mw) of not more than 2000 g/mol, such as not more than 1500 g/mol, or not more than 1200 g/mol, or not more than 1000 g/mol.

41. Process according to any of statements 1 to 17 and 21 to 25 and 27 to 40, wherein said saccharide components comprise C5 saccharides and C6 saccharides, and wherein the weight ratio of C6 to C5 saccharides obtained in said process is comprised between 20:1 to 1.2:1, and for instance between 15:1 and 1.5:1 , or between 10:1 and 2:1.

42. Process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said process comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting the lignocellulosic biomass of step a) with a composition comprising a reducing agent, wherein said reducing agent is a sulphur containing reducing agent and a solvent, wherein said solvent is an organic solvent, and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and wherein said lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition.

43. Process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said process comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting the lignocellulosic biomass of step a) with a composition comprising a reducing agent, wherein said reducing agent is a sulphur containing reducing agent and a solvent, wherein said solvent is an organic solvent, and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, wherein said lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition, and wherein said composition as applied in step b) is prepared by providing said sulphur containing reducing agent in a solid state and dissolving said sulfur reducing agent in said solvent.

44. Process according to statement 42 or 43, wherein said process is as defined in any one of statements 1 to 20, 26, 29-40.

45. Process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said process comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting the lignocellulosic biomass of step a) with a composition comprising a reducing agent, wherein said reducing agent is a sulphur containing reducing agent and a solvent, wherein said solvent is a mixture of an organic solvent and water, and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and d) obtaining saccharide components from said lignocellulosic biomass and isolating and recovering said saccharide components.

46. Process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said process comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting the lignocellulosic biomass of step a) with a composition comprising a reducing agent, wherein said reducing agent is a sulphur containing reducing agent and a solvent, wherein said solvent is a mixture of an organic solvent and water, and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and d) obtaining saccharide components from said lignocellulosic biomass and isolating and recovering said saccharide components. wherein said lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition, and wherein said composition as applied in step b) is prepared by providing said sulphur containing reducing agent in a solid state and dissolving said sulfur reducing agent in said solvent.

47. Process according to statement 45 or 46, wherein said process is as defined in any one of statements 1 to 17, 21-25, 27-41.

48. Lignin components comprising lignin monomers, lignin dimers and lignin oligomers obtained or obtainable from lignocellulosic biomass by the process of any of statements 1 to 47, wherein said lignin components comprise lignin monomers in an amount of at least 3%, and for instance of at least 5%; 6%, 7%; 10%; 12%; 15%; 20%; 25%, based on the total weight of the lignin components.

49. Lignin components according to statement 48, wherein said lignin components comprise unsaturated lignin monomers in an amount of at least 1%, and for instance of at least 3%; 5%; 7%; 10%; 12%; 15%; 20%; 25%, based on the total weight of the lignin components.

50. Lignin components according to statement 48 or 49, and wherein said lignin components have a weight average molecular weight (Mw) of not more than 2000 g/mol, such as not more than 1500 g/mol, or not more than 1200 g/mol, or not more than 1000 g/mol.

51. Saccharide components obtained or obtainable from lignocellulosic biomass by the process of any of statements 1 to 17, 21 to 25, 27 to 41, and 45 to 47, wherein said components comprise C5 and C6 saccharides at a weight ratio of C6 to C5 carbohydrates comprised between 20:1 to 1.2:1, and for instance between 15:1 and 1.5:1, or for instance between 10:1 and 2:1.

52. Use of lignin components according to any of statements 48 to 50 in the production of fuels.

53. Use of lignin components according to any of statements 48 to 50 in the production of chemicals such as bulk chemicals and fine chemicals and additives.

54. Use of lignin components according to any of statements 48 to 50 in pulp and paper industry.

55. Use of lignin components according to any of statements 48 to 50 in the production of antimicrobial agents, such as antibacterial, antiviral, antifungal or antiparasitic agents. 56. Use of saccharide components according to statement 51 , in the production of fuels.

57. Use of saccharide components according to statement 51, in the production of chemicals or in pulp and paper industry.

In general, the present invention thus relates to processes for treating lignocellulosic biomass and for producing lignin components from such lignocellulosic biomass.

In certain embodiments, a process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass is provided, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said wherein said process comprises the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting said lignocellulosic biomass with a composition comprising a reducing agent, preferably a sulphur containing reducing agent, and a solvent, wherein said solvent is an organic solvent, and obtaining lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers and wherein the lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition in step b).

In certain embodiments, a process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass is provided, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said wherein said process comprises the steps of: a) providing said lignocellulosic biomass as a solid biomass, b1) preparing a composition comprising a reducing agent, preferably a sulphur containing reducing agent, and a solvent, wherein said solvent is an organic solvent, wherein said composition is prepared by providing said sulphur containing reducing agent in a solid state and dissolving said sulfur reducing agent in said solvent; b2) contacting said lignocellulosic biomass provided in step a) with the composition as prepared in step b1) and isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers wherein said process is characterized in that the lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition in step b2). In certain embodiments, the present invention also provides a process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass comprising the steps of: a) providing said lignocellulosic biomass as a solid biomass, b) contacting said lignocellulosic biomass with a composition comprising a reducing agent, preferably a sulphur containing reducing agent, and a solvent, wherein said solvent is mixture of an organic solvent and water, and obtaining

(i) lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and

(ii) saccharide components comprising C5 and/or C6 saccharides, c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and d) isolating and recovering said saccharide components comprising C5 and/or C6 saccharides and wherein the lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition in step b).

In certain embodiments, a process for producing lignin components comprising lignin monomers, lignin dimers and lignin oligomers from lignocellulosic biomass is provided, wherein said lignocellulosic biomass comprises cellulose, hemicellulose and lignin, said wherein said process comprises the steps of: a) providing said lignocellulosic biomass as a solid biomass, b1) preparing a composition comprising a reducing agent, preferably a sulphur containing reducing agent, and a solvent, wherein said solvent is mixture of an organic solvent and water, wherein said composition is prepared by providing said sulphur containing reducing agent in a solid state and dissolving said sulfur reducing agent in said solvent; b2) contacting said lignocellulosic biomass provided in step a) with the composition as prepared in step b1) and isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and obtaining

(i) lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and

(ii) saccharide components comprising C5 and/or C6 saccharides, c) isolating and recovering said lignin components comprising lignin monomers, lignin dimers and lignin oligomers, and d) isolating and recovering said saccharide components comprising C5 and/or C6 saccharides wherein said process is characterized in that the lignocellulosic biomass provided in step a) is not chemically treated prior to contacting with said composition in step b2).

The process of the present invention thus involves a treatment of raw lignocellulosic biomass (e.g. softwood, hardwood or herbaceous materials) in an organic solvent or in a mixture of an organic solvent and water, in presence of a sulphur-containing reducing agent. Such process leads to fractionation of the biomass and the production of a solid fraction (i.e. pulp containing retained carbohydrates) and one organic liquid fraction (containing depolymerized lignin components), or two liquid fractions (when a mixture of an organic solvent and water is applied) of which one is an organic liquid fraction (containing depolymerized lignin components) and the other one is an aqueous fraction (containing solubilised carbohydrates).

The present process allows to simultaneously fractionate raw biomass and convert native lignin into low molecular weight component within a single reaction step, by directly treating the raw lignocellulosic biomass with a composition that comprises a sulphur- containing reducing agent and an organic solvent, optionally in combination with water.

Processes according to the invention will now be described in more detail having due regard to the reactants and reaction conditions.

BIOMASS

The term “lignocellulosic biomass” as used herein refers to biomass that comprises or contains cellulose, hemicellulose, and lignin. Lignocellulosic biomass includes, but is not limited to plant parts, fruits, vegetables, wood, chaff, grain, grasses, hay, weeds, roots, bark and any lignocellulose containing biological material or material of biological origin. Plants can be in their natural state or genetically modified, e.g., to increase the cellulosic or hemicellulosic or lignin portion of the cell wall. Lignocellulosic biomass can be derived from agricultural crops, crop residues, trees, wood or woodchips, wood sawdust, grasses, and other sources. Lignocellulosic biomass can also include cell or tissue cultures; for example, lignocellulosic biomass can include plant cell culture(s) or plant tissue culture(s). In one embodiment, the lignocellulosic biomass as used herein is non-woody plant material, such as grasses, dicots, monocots, etc.

In another embodiment, the lignocellulosic biomass as used herein is woody plant material or wood. The woody material or the wood may be any kind of wood, including hardwood and softwood. A non-limiting list of woods includes pine, birch, spruce, maple, ash, mountain ash, redwood, alder, elm, oak, fir, prune, eucalyptus, aspen, hemlock, larch, poplar and beech. In a preferred embodiment the lignocellulosic biomass is hardwood, i.e. wood from angiosperm trees. Preferred examples of hardwood include birch and poplar. In another embodiment the lignocellulosic biomass is softwood, i.e. wood from gymnosperm trees such as conifers. Preferred examples of softwood include spruce or pine.

In an embodiment, the lignocellulosic biomass as used herein is derived from herbaceous plants and agricultural residues. Preferred examples of herbaceous plants and agricultural residues include wheat straw, wheat bran, corn stover, barley straw, sugar cane bagasse, prairie grasses, foxtail grasses, miscanthus, beet pulp, chicory pulp.

The lignocellulosic biomass is used in a process according to the invention as solid biomass. In other words, the lignocellulosic material is applied as raw material or feedstock. According to the present invention, the lignocellulosic material is directly contacted with a composition as defined herein and is not chemically treated prior to contacting with said composition, e.g. it is not chemically treated or modified by oxidation or reduction. Thus, in accordance with the present process, raw lignocellulosic biomass is contacted with a composition as defined herein. In accordance with the present invention, the lignocellulosic biomass is applied as solid biomass in the present process. The term “solid biomass” is used herein as synonym for raw biomass or raw biomass material and refers to biomass that has not been chemically processed or treated. In accordance with the invention, solid biomass (raw biomass) is applied as substrate for the process of the invention, i.e. biomass that has not been subjected to any treatment with any chemical agent prior to being contacted with a composition as defined. Solid biomass may however undergo mechanical pre-treatment prior to being contacted with a composition comprising a reducing agent and a solvent as defined herein, in order to reduce its size or volume. However, such mechanical pre-treatment does not include any use of chemical component(s) or chemical composition.

The lignocellulosic biomass provided in step a) is “not chemically treated” prior to contacting with said composition. The term “not chemically treated” as used herein means that the biomass applied in the present processes has not been contacted with or subjected to any reaction with a chemical component or chemical composition.

In one embodiment, lignocellulosic biomass applied in the present process is mechanically treated prior to contacting with a composition as defined herein to reduce the size of said biomass. Preferably, the lignocellulosic biomass is provided in step a) in the present process in the form of particles or powder. The biomass may be ground to small size particles or powder using any suitable technique. For instance, mechanical size reduction may comprise cutting, chipping, grinding, milling, shredding, shearing, or any combination thereof. In a preferred embodiment, the lignocellulosic biomass is provided in step a) of the present invention in the form of particles or powder having a particle size of 10 cm or less, or of 5 cm or less, or of 2 cm or less, or of 1 cm or less, or of 5 mm or less, or of 1 mm or less; or of 500 pm.

In an example, a lignocellulosic biomass as applied in a process according to the invention is wood, preferably hardwood, and is provided in the form of saw dust or wood chips.

In another example a lignocellulosic biomass as applied in a process according to the invention is softwood, and is for example provided in the form of saw dust or wood chips.

In an example, a lignocellulosic biomass as applied in a process according to the invention is herbaceous biomass.

Composition for treating lignocellulosic biomass

In accordance with a process of the present invention, lignocellulosic biomass as defined herein is contacted with a composition comprising, and preferably consisting of, a reducing agent and a solvent. In certain embodiments, said solvent is an organic solvent as defined herein. In certain embodiments, said solvent is a mixture of an organic solvent as defined herein and water.

In certain embodiments, a composition as provided herein and as applied in the present process, is prepared by providing said reducing agent in a solid state and dissolving said sulfur reducing agent in said solvent, wherein said solvent is an organic solvent or is a mixture of an organic solvent and water.

In a preferred embodiment, a composition as provided herein and as applied in the present process, is prepared by providing said sulphur containing reducing agent in a solid state and dissolving said sulfur reducing agent in said solvent, wherein said solvent is an organic solvent or is a mixture of an organic solvent and water. Reducing agent

In accordance with a process of the present invention, lignocellulosic biomass as defined herein is contacted with a composition comprising a reducing agent.

In an embodiment, said reducing agent is a reducing agent that does not contain sulphur. In an embodiment, said reducing agent may be borohydride, for instance selected from the group comprising sodium borohydride, potassium borohydride, and lithium borohydride.

In another embodiment said reducing agent is a sulphur containing reducing agent. A sulphur containing reducing agent as used herein may be selected from the group comprising, and preferably consisting of, dithionite, sulfite, thiosulphate, metabisulfite, sulfinate, thiourea, thiourea oxide, thiourea dioxide, thiourea trioxide, hydroxymethane sulfinate, hydroxyethane sulfinate, hydroxypropane sulfinate, hydroxybutane sulfinate, thiophenol, and sulfur dioxide. In an embodiment the sulphur containing reducing agent is dithionite. In another embodiment the sulphur containing reducing agent is a sulfite or a sulfite forming agent. In another embodiment the sulphur containing reducing agent is a thiosulphate. In another embodiment the sulphur containing reducing agent is a metabisulfite. A non-limiting list of sulphur containing reducing agents that may be used in the present invention include sodium or potassium dithionite, sodium or potassium hydroxymethane sulfinate, sodium or potassium sulfite, sodium or potassium bisulfite, sodium or potassium thiosulfate, or any combination thereof.

In an embodiment a sulphur containing reducing agent as used in a process according to the invention is selected from the group comprising, and preferably consisting of, sodium or potassium dithionite, sodium or potassium sulfite, sodium or potassium thiosulfate, sodium or potassium metabisulfite, sodium or potassium sulfinate, thiourea oxide, thiourea dioxide, thiourea trioxide, sodium or potassium hydroxymethane sulfinate, sodium or potassium hydroxyethane sulfinate, sodium or potassium hydroxypropane sulfinate, sodium or potassium hydroxybutane sulfinate, thiophenol, and sulfur dioxide, or any combination thereof.

In a preferred embodiment the sulphur containing reducing agent as used in a process according to the invention is selected from the group comprising sodium dithionite (CAS Number: 7775-14-6), potassium dithionite (CAS Number: 14293-73-3), sodium sulfite (CAS Number: 7757-83-7), potassium sulfite (CAS Number: 10117-38-1) sodium thiosulfate (CAS Number: 10102-17-7) and potassium thiosulfate (CAS Number: 10294-66-3). In a particularly preferred embodiment the sulphur containing reducing agent as used in a process according to the invention is sodium dithionite (Na2S2C>4). In accordance with the invention a process is provided, wherein the reducing agent, and preferably the sulphur containing reducing agent, is applied at a concentration of between 1.5 and 40 g/L, and preferably at a concentration of between 3 and 25 g/L. In an embodiment, the sulfur containing reducing agent may be applied in a process according to the invention at a concentration of between 1.5 and 40 g/L, and preferably at a concentration of between 3 and 25 g/L.

In accordance with the invention a process is provided, wherein the reducing agent, and preferably the sulphur containing reducing agent, is applied in an amount of 5 to 40 wt%, based on the total weight of said lignocellulosic biomass, and preferably in an amount of 6 to 35 wt% or of 7 to 30 wt%, or of 10 to 20 wt%, or of 10 to 17 wt%, based on the total weight of said lignocellulosic biomass.

In an embodiment, the sulphur containing reducing agent is applied in a process according to the invention in an amount of 5 to 40 wt% based on the total weight of said lignocellulosic biomass, and for instance in an amount of 6 to 35 wt% or of 7 to 30 wt%, or of 10 to 20 wt%, or of 10 to 17 wt%, based on the total weight of said lignocellulosic biomass.

In certain preferred embodiments, a reducing agent as applied in the present process refers to an agent that is in a solid state. In certain preferred embodiments, a reducing agent as defined herein is used in a solid form (solid state) to prepare a composition as defined herein. In certain preferred embodiments, a reducing agent as defined is provided in solid form, e.g. the form of a powder, and dissolved in a solvent, preferably an organic solvent, as defined herein to obtain a composition as defined herein. In another example, a recducing agent is provided in solid form, e.g. the form of a powder and dissolved in a solvent, preferably in a mixture of an organic solvent and water, as defined herein to obtain a composition as defined herein.

In certain preferred embodiments, a sulphur containing reducing agent as defined herein is used in a solid form (solid state) to prepare a composition as defined herein. In certain embodiments, a sulphur containing reducing agent is provided in solid form, e.g. the form of a powder, and dissolved in a solvent, preferably an organic solvent, as defined herein to obtain a composition as defined herein. In another example, a sulphur containing reducing agent is provided in solid form, e.g. the form of a powder and dissolved in a solvent, preferably in a mixture of an organic solvent and water, as defined herein to obtain a composition as defined herein.

The present invention therefore in certain embodiments relates to processes wherein lignocellulosic biomass as defined herein is treated with a composition comprising a solvent, i.e. an organic solvent or a mixture of an organic solvent and water, wherein solid sulphur containing reducing agent is applied in a solid state and contacted with or dissolved in said solvent to form a suitable composition. Solvent

In certain embodiments of a process according to the present invention, the solvent applied in the composition is an organic solvent, preferably an alcohol, more preferably a C1 to C10 alcohol, even more preferably a C1 to C5 alcohol. In a preferred embodiment, the organic solvent is an alcohol selected form the group comprising methanol, ethanol, 1-propanol, 2-propanol and butanol, and preferably is methanol or butanol or 2-propanol (isopropanol).

In certain embodiments of a process according to the present invention, the solvent applied in the composition is a mixture of an organic solvent and water, preferably a mixture of an alcohol and water, more preferably a mixture of a C1 to C10 alcohol and water, even more preferably a mixture of a C1 to C5 alcohol and water. In a preferred embodiment, the solvent is a mixture of an alcohol and water, wherein said alcohol is selected form the group comprising methanol, ethanol, 1-propanol, 2-propanol (isopropanol) and butanol, and preferably is methanol or butanol or 2-propanol (isopropanol). Preferably, the volume ratio between the water and the organic solvent is comprised between 10:1 and 1 :10, such as between 7:1 and 1:1 or between 5:1 and 1:1, or between 3:1 and 1 :1 or between 2:1 and 1:1, or between 1 :1 and 10:1, or between 1:1 and 1 :7, or between 1.1 and 1:5, or between 1:1 and 1:3, or between 1 :1 and 1 :2.

In certain embodiments of a process according to the present invention lignocellulosic biomass is contacted with a composition that comprises, and preferably consists, of an organic solvent and a sulfur containing reducing agent. In an embodiment, a composition is applied in a process according to the invention that comprises, and preferably consists of, a mixture of sodium dithionite and methanol. In an embodiment a composition is applied in a process according to the invention that comprises, and preferably consists of, a mixture of sodium dithionite and ethanol. In an embodiment a composition is applied in a process according to the invention that comprises, and preferably consists of, a mixture of sodium dithionite and 1-propanol. In an embodiment a composition is applied in a process according to the invention that comprises, and preferably consists of, a mixture of sodium dithionite and 2-propanol (isopropanol). In an embodiment a composition is applied in a process according to the invention that comprises, and preferably consists of, a mixture of sodium dithionite and butanol.

In certain embodiments, a process according to the invention comprises the step of contacting lignocellulosic biomass with a composition that comprises, and preferably consists, of an organic solvent, a sulfur containing reducing agent and water. When a composition comprises a mixture organic solvent and water, the volume ratio of organic solvent to water in said composition is preferably comprised between 10:1 and 1:10, such as between 7:1 and 1 :1 or between 5:1 and 1 :1 , or between 3:1 and 1 :1 or between 2:1 and 1 :1 , or between 1:1 and 10:1 , or between 1 :1 and 1 :7, or between 1.1 and 1 :5, or between 1 :1 and 1:3, or between 1 :1 and 1:2. In an embodiment, the volume ratio of organic solvent to water in a composition as defined herein is around 1 :1. In another embodiment, the volume ratio of organic solvent to water in a composition as defined herein is around 3:1. In another embodiment, the volume ratio of organic solvent to water in a composition as defined herein is around 1:3.

In an embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of a sulfur containing reducing agent, preferably selected from the group consisting of sodium dithionite, sodium sulfite and sodium thiosulfate, methanol and water. In another embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of a sulfur containing reducing agent, preferably selected from the group consisting of sodium dithionite, sodium sulfite and sodium thiosulfate, and ethanol and water. In another embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of a sulfur containing reducing agent, preferably selected from the group consisting of sodium dithionite, sodium sulfite and sodium thiosulfate, and 1-propanol and water. In another embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of a sulfur containing reducing agent, preferably selected from the group consisting of sodium dithionite, sodium sulfite and sodium thiosulfate, and 2-propanol and water. In another embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of a sulfur containing reducing agent, preferably selected from the group consisting of sodium dithionite, sodium sulfite and sodium thiosulfate, and butanol and water.

In an embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium dithionite, methanol and water wherein the volume ratio of methanol to water is between 10:1 and 1 :10, and for instance between 5: 1 and 1 :1 , or between 3: 1 and 1 :1 , or between 1 : 1 and 1 :10, or between 1 : 1 and 1 :5, or between 1 : 1 and 1 :3, and for instance is 3:1 , or 1 :1 , or 1 :3. In an embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium dithionite, ethanol and water, wherein the volume ratio of ethanol to water is between 10:1 and 1 :10, and for instance between 5:1 and 1 :1 , or between 3:1 and 1 :1 , or between 1 :1 and 1 :10, or between 1 :1 and 1 :5, or between 1:1 and 1:3, and for instance is 3:1, or 1 :1 , or 1:3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium dithionite, 1 -propanol and water, wherein the volume ratio of 1 -propanol to water is between 10:1 and 1:10, and for instance between 5: 1 and 1:1, or between 3: 1 and 1 :1 , or between 1:1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1, or 1:1, or 1:3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium dithionite, isopropanol and water, wherein the volume ratio of isopropanol to water is between 10:1 and 1:10, and for instance between 5:1 and 1:1, or between 3:1 and 1:1, or between 1:1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1, or 1:1, or 1:3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium dithionite, butanol and water, wherein the volume ratio of butanol to water is between 10:1 and 1:10, and for instance between 5: 1 and 1:1, or between 3: 1 and 1:1, or between 1 : 1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1, or 1:1, or 1:3. In another embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium thiosulfate (NaaSaCh), methanol and water wherein the volume ratio of methanol to water is between 10:1 and 1:10, and for instance between 5:1 and 1:1, or between 3:1 and 1:1, or between 1:1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1 , or 1:1, or 1:3. In an embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium thiosulfate, ethanol and water, wherein the volume ratio of ethanol to water is between 10:1 and 1:10, and for instance between 5: 1 and 1:1, or between 3: 1 and 1:1, or between 1:1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1, or 1:1, or 1 :3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium thiosulfate, 1-propanol and water, wherein the volume ratio of 1 -propanol to water is between 10:1 and 1:10, and for instance between 5:1 and 1:1, or between 3:1 and 1:1, or between 1:1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1 , or 1:1, or 1:3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium thiosulfate, isopropanol and water, wherein the volume ratio of isopropanol to water is between 10:1 and 1:10, and for instance between 5: 1 and 1:1, or between 3: 1 and 1:1, or between 1 : 1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1, or 1:1, or 1:3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium thiosulfate , butanol and water, wherein the volume ratio of butanol to water is between 10:1 and 1:10, and for instance between 5:1 and 1:1, or between 3:1 and 1:1, or between 1:1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1, or 1:1, or 1:3.

In another embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium sulfite (Na2SC>3), methanol and water wherein the volume ratio of methanol to water is between 10:1 and 1:10, and for instance between 5:1 and 1 :1 , or between 3:1 and 1:1, or between 1:1 and 1:10, or between 1:1 and 1:5, or between 1 :1 and 1 :3, and for instance is 3:1 , or 1 :1 , or 1 :3. In an embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium sulfite, ethanol and water, wherein the volume ratio of ethanol to water is between 10:1 and 1 :10, and for instance between 5:1 and 1 :1 , or between 3:1 and 1 :1 , or between 1 :1 and 1 :10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1 , or 1:1, or 1:3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium sulfite, 1 -propanol and water, wherein the volume ratio of 1 -propanol to water is between 10:1 and 1 :10, and for instance between 5:1 and 1 :1 , or between 3:1 and 1 :1 , or between 1 :1 and 1 :10, or between 1 :1 and 1 :5, or between 1 :1 and 1 :3, and for instance is 3:1 , or 1 :1 , or 1 :3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium sulfite, isopropanol and water, wherein the volume ratio of isopropanol to water is between 10:1 and 1 :10, and for instance between 5:1 and 1 :1 , or between 3:1 and 1 :1 , or between 1 :1 and 1 :10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1 , or 1:1, or 1:3. In one embodiment, a composition as herein applied comprises, and preferably consists of, a mixture of sodium sulfite, butanol and water, wherein the volume ratio of butanol to water is between 10:1 and 1:10, and for instance between 5: 1 and 1:1, or between 3: 1 and 1:1 , or between 1:1 and 1:10, or between 1:1 and 1:5, or between 1:1 and 1:3, and for instance is 3:1 , or 1 :1 , or 1 :3.

Reaction conditions

A process according to the invention comprises contacting lignocellulosic biomass with a composition as defined herein at a temperature of 175°C or higher or 190°C or higher or 200°C or higher. One preferred temperature range at which a lignocellulosic biomass as defined herein is contacted with a composition as defined herein is at a temperature comprised between 175°C and 250°C, or between 175°C and 230°C and preferably comprised between 180°C and 23 °C, or between 180°C and 250°C, and for instance comprised between 190°C and 230°C or between 190 °C and 220°C or between 190°C and 210°C, or between 195°C and 210°C, or between 200°C and 225°C.

Preferably said lignocellulosic biomass as defined herein may be contacted with a composition as defined herein for 0.75 hour or longer; such as for 1 hour or longer, such as for 3 hours or longer, for 6 hours or longer, for 12 hours or longer, and may be performed in an inert atmosphere or in an atmosphere containing inert gas. The biomass and the composition may be stirred or shaken prior to or during the contacting phase. Preferably, the reaction may be performed at an elevated pressure such as 2 bar or higher, or 4 bar or higher. The elevated pressure may be obtained by performing the reaction in a sealed container. Advantageously, there are no particular requirements to apply a certain initial pressure when carrying out the reaction according to the present invention.

In certain embodiments, a process according to the invention is provided that involves the step of obtaining - besides lignin components as provided herein- saccharide components from the lignocellulosic biomass. While said lignin components are essentially derived from the lignin of said lignocellulosic biomass, said saccharide components are essentially derived from the cellulose and hemicellulose of said lignocellulosic biomass. In accordance with a process as disclosed herein also such saccharide components may be isolated and recovered from the treated biomass.

Lignin and saccharide components as defined herein may be isolated and recovered by any suitable technique such as but not limited to filtration, evaporation, distillation or centrifugation or any other suitable technique.

Advantageously a process according to the invention is performed in the absence of a catalyst, such as in the absence of a metal catalyst, in the absence of a transition metal catalyst and/or in the absence of a precious metal catalyst. In other words, a process according to the invention comprises the step of contacting lignocellulosic material as provided herein with a composition as provided herein in the absence of a catalyst, such as in the absence of a metal catalyst, in the absence of a transition metal catalyst or in the absence of a precious metal catalyst. In certain embodiments, a process according to the invention is also performed in the absence of hydrogen gas. In other words, a process according to the invention comprises the step of contacting lignocellulosic material as provided herein with composition as defined herein and in the absence of hydrogen gas. A process according to the invention thus advantageously permits to eliminate the use of hydrogen gas and of a precious metal and/or transition metal catalyst. The use of precious/transition metal catalysts and high pressures of hydrogen gas constitute primary limitations to process scale-up. Moreover, eliminating the use of catalytic systems in accordance with a process according to the invention avoids any problems and costs associated with separation of catalyst from obtained reaction products and catalyst recover/regeneration operations. The possibility to work in absence of hydrogen gas and without initial pressurization of a reactor, also offers an advantage in terms of safety of the operation. Furthermore, the present invention provides a process that advantageously enables effective biomass delignifi cation and lignin depolymerization, yielding lignin monomers, dimers and oligomers, in absence of hydrogen gas and of a catalyst, while at the same time preserving saccharide components that are contained in the biomass for further isolation recovery and use. LIGNIN COMPONENTS

As used herein the term “lignin components” refers to chemical compounds that are derived from the lignin contained in the lignocellulosic biomass, and comprise, preferably consist of, lignin monomers, lignin dimers and lignin oligomers. The term “lignin components” may in certain embodiment be used as synonym for a “lignin composition” that comprises, preferably consists of, lignin monomers, lignin dimers and lignin oligomers.

Lignin components are obtained as a result of the chemical modification or depolymerization of lignin present within the initial lignocellulosic biomass when carrying out a process according to the invention. In such reaction the initial and complex lignin structure present in the biomass is processed into smaller fragments, yielding lignin monomers, lignin dimers (comprising two phenylpropane units), and lignin oligomers (comprising more than two phenylpropane units, with molecular weight not higher than 2000 Da).

“Lignin monomers” as used herein include saturated lignin monomers and unsaturated lignin monomers. Saturated lignin monomers as used herein to refer to compounds derived from lignin that have saturated alkyl side chains. Unsaturated lignin monomers as used herein refer to compounds derived from lignin that have unsaturated alkyl side chains. In a preferred embodiment, said lignin monomers comprise unsaturated and/or saturated lignin monomers having the formula (I) wherein R ¹ and R ³ are independently H or OCH ₃ , wherein R ² is selected from the group consisting of H, OH, CH ₃ , CH ₂ OH, CHO, COCH ₃ , CH ₂ CH ₃ , (CH ₂ ) ₂ OH, CH ₂ CHO, CH ₂ COCH ₃ , (CH ₂ ) ₂ COCH ₃ , (CH ₂ ) ₂ CH ₃ , CH ₂ CHCH ₂ , (CH) ₂ CH ₃ , (CH ₂ ) ₃ OH, CH ₂ (CH) ₂ OH, (CH) ₂ CH ₂ OH, (CH) ₂ CHO, (CH ₂ ) ₂ CHO and CO(CH ₂ ) ₂ CH ₃ , and wherein R ⁴ is OH or OCH ₃ or OCH ₂ CH ₃ .

Non-limitative examples of saturated lignin monomers that may be obtained with a process according to the invention include but are not limited to 4-propylguaiacol (2-methoxy-4- propylphenol - herein also denoted as “propylguaiacol”), 4-ethylguaiacol (4-ethyl-2- methoxyphenol), vanillin (4-hydroxy-3-methoxybenzaldehyde), syringaldehyde (4-hydroxy- 3,5-dimethoxybenzaldehyde), acetoguaiacone (1-(4-Hydroxy-3-methoxyphenyl)ethanone), acetosyringone (1-(4-hydroxy-3,5-dimethoxyphenyl)ethanone), guaiacylacetone (1-(4- hydroxy-3-methoxyphenyl)propan-2-one), syringylacetone (4-(4-hydroxy-3,5- dimethoxyphenyl)butan-2-one), butyrovanillone (1-(4-hydroxy-3-methoxyphenyl)butan-1-one), 4-methylsyringol (2,6-dimethoxy-4-methylphenol), 4-ethylsyringol (4-ethyl-2,6- dimethoxyphenol), 4-propylsyringol (2,6-dimethoxy-4-propylphenol, herein also denoted as “propylsyringol”), dihydroconiferyl alcohol (4-(3-hydroxypropyl)-2-methoxyphenol), dihydrosinapyl alcohol (4-(3-hydroxypropyl)-2,6-dimethoxyphenol), desaspidinol (1 -(2,6- Dihydroxy-4-methoxyphenyl)-1-butanone), and 4-Ethoxy-3,5-dimethoxybenzaldehyde.

Non-limitative examples of unsaturated lignin monomers that may be obtained with a process according to the invention include but are not limited to 4-propenylsyringol (2,6- dimethoxy-4-[(Z)-prop-1-enyl]phenol, and herein also denoted as “propenylsyringol”), 4- propenylguaiacol (isoeugenol or 2-methoxy-4-[(£)-prop-1-enyl]phenol, and herein also denoted as “propenylguaiacol”), 4-vinylguaiacol (4-ethenyl-2-methoxyphenol), coniferaldehyde ((£)-3-(4-hydroxy-3-methoxyphenyl)prop-2-enal), coniferyl alcohol (4- [(E)-3-hydroxyprop-1-enyl]-2-methoxyphenol), syringaldehyde (4-hydroxy-3,5- dimethoxybenzaldehyde), sinapyl aldehyde ((£)-3-(4-hydroxy-3,5-dimethoxyphenyl)prop- 2-enal) and sinapyl alcohol (4-[(£)-3-hydroxyprop-1-enyl]-2,6-dimethoxyphenol).

A process as described herein thus allows recovering unsaturated lignin monomers from lignocellulosic biomass. This aspect is unexpected as it implies that the process preserves the double bond functionalities of lignin units, without incurring extensive re-condensation of the depolymerized lignin.

A process according to the invention also provides lignin dimers and lignin oligomers. “Lignin dimers” as used herein refer to compounds derived from lignin comprising two linked lignin monomers as defined herein. Non-limitative examples of lignin dimers that may be obtained with a process according to the invention include but are not limited to guaiacylglycerol-p-guaiacyl ether, veratrylglycerol- -guaiacyl ether, syringylglycerol-b- guaiacyl ether, pinoresinol, syringaresinol, and dehydrodiisoeugenol.

Other examples of lignin dimers as encompassed by the present invention include lignin dimers having the formula (II), (III) or (IV),

wherein R ⁹ is H, OCH ₃ , or (Chh^CHs, wherein R ⁵ is H or OH, wherein R ⁶ is H or CH ₂ OH, and wherein R ⁷ and R ⁸ are independently H or OCH ₃ .

In an example, a lignin dimer has formula (IV) wherein R ⁹ is H, R ⁵ is H, R ⁶ is H, R ⁷ is OCH ₃ and R ⁸ is H. In another example, a lignin dimer has formula (IV) wherein R ⁹ is H, R ⁵ is H, R ⁶ is H, R ⁷ is OCH ₃ and R ⁸ is OCH ₃ . In another example, a lignin dimer has formula (IV) wherein R ⁹ is H, R ⁵ is H, R ⁶ is CH ₂ OH, R ⁷ is OCH ₃ and R ⁸ is H. In another example, a lignin dimer has formula (IV) wherein R ⁹ is OCH ₃ , R ⁵ is H, R ⁶ is H, R ⁷ is OCH ₃ and R ⁸ is OCH ₃ . In another example, a lignin dimer has formula (IV) wherein R ⁹ is H, R ⁵ is H, R ⁶ is CH ₂ OH, R ⁷ is OCH ₃ and R ⁸ is OCH ₃ .ln another example, a lignin dimer has formula (IV) whereinR ⁹ is OCH ₃ , R ⁵ is H, R ⁶ is CH ₂ OH, R ⁷ is OCH ₃ and R ⁸ is OCH ₃ . In another example, a lignin dimer has formula (IV) wherein R ⁹ is (CH ₂ ) ₂ CH ₃ , R ⁵ is OH, R ⁶ is H, R ⁷ is H and R ⁸ is OCH ₃ . In another example, a lignin dimer has formula (IV) wherein R ⁹ is (CH ₂ ) ₂ CH ₃ , R ⁵ is OH, R ⁶ is CH ₂ OH, R ⁷ is H and R ⁸ is OCH ₃ . In another example, a lignin dimer has formula (IV) wherein R ⁹ is (OH ₂ ) OH ₃ , R ⁵ is OH, R ⁶ is H, R ⁷ is OCH ₃ and R ⁸ is OCH ₃ . In another example, a lignin dimer has formula (IV) wherein R ⁹ is (CH ₂ ) ₂ CH ₃ , R ⁵ is OH, R ⁶ is CH ₂ OH, R ⁷ is OCH ₃ and R ⁸ is OCH ₃ .

“Lignin oligomers” as used herein refers to compounds derived from lignin comprising more than two linked lignin monomers as defined.

YIELD - Conversion rates

A process according to the present invention provides high conversion efficiency, especially in terms of delignification of the initial lignocellulosic biomass, and/or in terms of isolating and recovering valuable components from processed lignocellulosic biomass. The terms “conversion efficiency” or “conversion rate” or “yield” are used interchangeably herein and have their ordinary meaning as known to those skilled in the art: i.e. they refer in general to the weight of a product made from the weight of a substrate (herein the lignocellulosic biomass). In general, the term can be expressed as a percentage yield of the product from a starting weight of substrate.

As mentioned above, a process according to the present invention provides high delignification yields of the lignocellulosic biomass. In other words, a process as provided herein allows efficient isolation and recovery of lignin components as defined herein from the biomass. The delignification yield of lignocellulosic biomass, also indicated with Y _D herein, is defined as the total weight of the lignin components obtained in a process as provided herein over the total weight of lignin present in lignocellulosic biomass provided in said process. In accordance with the present invention, the total weight of lignin present in lignocellulosic biomass corresponds herein to the total weight of acid insoluble lignin (AIL) contained in the biomass provided in the process. Typically, acid soluble lignin is negligible especially in wood samples and insoluble lignin (also referred to as Klason lignin) is commonly taken as a reference.

Delignification yield is represented with the following formula:

YD (in %) = WLC/WAIL wherein WLC is the total weight of lignin components obtained by a process according to the invention, and

WAIL is the total weight of acid insoluble lignin contained in the lignocellulosic biomass processed in a process according to the invention.

Methods for determining the total weight of lignin components obtained with the process according to the invention and to determine AIL contained in biomass are well known in the art and can be readily applied by a skilled person. Methods applicable to present invention are disclosed in the example section.

In certain embodiments of the invention, the present invention relates to a process wherein the delignification yield of the lignocellulosic biomass (YD) as defined herein is at least 48%, at least 50%, at least 60%, and for instance at least 75%; 80%; 85%; 90%; 95%; 98%, 99%, or is 100%.

A process according to the present invention further provides for the isolation and recovery of lignin monomers from lignocellulosic biomass at a considerable yield. As indicated above, lignin monomers may include unsaturated as well as saturated lignin monomers.

The yield of lignin monomer isolation and recovery from lignocellulosic biomass is indicated with Y _M herein, and is defined as

Y _M (in %) = WLM/WAIL wherein

WLM is the total weight of lignin monomers obtained by a process according to the invention, and

WAIL is the total weight of acid insoluble lignin contained in the lignocellulosic biomass processed in a process according to the invention.

The total weight of lignin monomers obtained in a process according to the invention may be determined via a GC-FID procedure such as disclosed in the example section below. The total weight of acid insoluble lignin contained in the initial biomass is determined as indicated herein.

In certain embodiments of the invention, the present invention relates to a process wherein the lignin monomer yield (Y _M ), as defined herein, is at least 3%, and preferably at least 5%; 6%; 7%; 10%; 12%; 15%; 20%; or 25%.

Lignin monomers as obtained with a process according to the invention may comprise or consist of saturated lignin monomers. Therefore, in certain embodiments, a process is provided wherein lignin components are obtained that comprise saturated lignin monomers at a yield of saturated lignin monomers (YMS) of at least 1%, such as at least 3%; 5%; 6%; 7%; 10%; 12%; 15%; 20%; 25%, and wherein said saturated lignin monomer yield (YMS) is expressed as :

YMS (in %) = WLMS/WAIL wherein

WLMS is the total weight of saturated lignin monomers obtained by a process according to the invention, and

WAIL is the total weight of acid insoluble lignin contained in the lignocellulosic biomass processed in a process according to the invention.

Lignin monomers as obtained with a process according to the invention may comprise or consist of unsaturated lignin monomers. In certain embodiments of the invention, a process is thus provided wherein lignin components are obtained that comprise or consists of unsaturated lignin monomers at a yield of unsaturated lignin monomers (YMUS) of at least 1%, and preferably at least 3%; 5%; 6%; 7%; 10%; 12%; 15%; 20%; 25%, and wherein said unsaturated lignin monomer yield (YMUS) is expressed as :

YMUS (in %) = WLMUS/WAIL wherein

WLMUS is the total weight of unsaturated lignin monomers obtained by a process according to the invention, and

WAIL is the total weight of acid insoluble lignin contained in the lignocellulosic biomass processed in a process according to the invention.

Determination of the total weight of saturated or unsaturated monomers in the lignin components can be done by GC-FID and GC-MS methodology such as disclosed in the example section below. Lignin components as obtained according to a process of the present invention have a relatively low weight average molecular weight. In particular, lignin components are obtained according to a process of the present invention having a weight average molecular weight (Mw) of not more than 2000 g/mol, such as not more than 1500 g/mol, or not more than 1200 g/mol or not more than 1000 g/mol, or not more than 900 g/mol, or not more than 800 g/mol. In one embodiment lignin components as obtained herein have a weight average molecular weight (Mw) comprised between 400 and 2000 g/mol, and for instance comprised between 400 and 1200 g/mol and for instance comprised between 800 and 1500 g/mol. The weight average molecular weight (Mw) of the lignin components can be determined using techniques that are well known in the art such as gel permeation chromatography as disclosed in the example section below.

SACCHARIDE COMPONENTS

As used herein the term “saccharide components” refers to compounds that are derived from lignocellulosic biomass, and preferably from the cellulose and/or hemicellulose of such biomass. In certain embodiments, the term “saccharide components” is used as synonym for “saccharide composition”.

Saccharide components as obtained herein may include mono, di-, oligo- or polysaccharides derived from cellulose and hemicellulose in said lignocellulosic biomass. Non limitative examples of saccharide components that may be obtained from a lignocellulosic biomass using a process according to the invention include but are not limited to xylan (i.e. a C5 polysaccharide) and glucan (i.e. a C6 polysaccharide).

A process according to the invention permits to recover saccharide components as well as lignin components from lignocellulosic biomass, and thus maximizes the recovery and valorization of components from the lignocellulosic biomass.

In an embodiment, a process is provided, wherein said saccharide components derived from said lignocellulosic biomass comprise C5 saccharides and C6 saccharides, and wherein the weight ratio of C6 to C5 saccharides obtained in said process is comprised between 20:1 to 1.2:1, or between 20:1 and 1.5:1, or between 15:1 and 1.5:1, or between 10:1 and 2:1. In other words, the certain embodiments, a process according to the invention permits to provide saccharide components that are enriched in C6 saccharides as compared to C5 saccharides.

In certain embodiments, saccharide components obtained from a lignocellulosic biomass using a process according to the invention are present the lignocellulosic biomass that remains after processing thereof (i.e. the pulp), and may be isolated and recovered therefrom. In certain embodiments, the reducing agent, such as the sulphur containing reducing agent, as defined herein, is present in the lignocellulosic biomass that remains after processing thereof (i.e. the pulp).

APPLICATIONS / USES

Lignin components and/or saccharide components as obtained from lignocellulosic biomass according to a process according to the invention, may be used as materials in various downstream processes, for instance in the preparation of fuels, polymers, bulk or fine chemicals, pharmaceuticals, antimicrobial agents, polymers, as additives, etc.

For instance, lignin components and/or saccharide components as provided herein, may be used in refinery processes or as a material for preparing fuel or fuel additives. In another example, lignin components and/or saccharide components as provided herein, may be used to prepare polymers, such as foams, plastics, rubbers, or to prepare fine chemicals such as aromatic compounds, or as additives.

Possible applications of lignin components as disclosed herein include but are not limited to for instance a use in the production of polymers or plastics, such as but not limited to polyurethanes, polycarbonates, epoxy resins, etc, or an application as polymer additive, additive for inks and varnishes, as cement additive.

Lignin components and/or saccharide components as obtained from lignocellulosic biomass according to a process of the invention may also be used in pulp and paper industry.

The invention will now be illustrated by the following, non-limiting illustrations of particular embodiments of the invention.

EXAMPLES

Examples 1 to 4

Test Methods

The following test methods were used.

Determination of non-volatile water and ethanol extractives

Raw (solid) biomass was finely grounded (2 mm particles for herbaceous materials / 0.5 mm particles for woody material) and subjected to two consecutive extractions, first with pure water, then with pure ethanol, using a Soxhlet extractor. The water and ethanol extracts were collected separately and dried at 60 °C overnight, then at 105 °C for 1 hour. The dried residues were weighed to determine the amount of non-volatile water extractives and non-volatile ethanol extractives. Determination of total weight of lignin components

After contacting a lignocellulosic biomass with a composition as provided in the invention, a liquid fraction as obtained was separated from the pulp by centrifugation (8000 rpm, 10 min). The liquid fraction was then filtered using glass fiber filters (pore size 1 pm). When two liquid phases were present (organic and aqueous phase), these were separated using a separating funnel.

A sample of the selected liquid phase (~5 ml) was dried under nitrogen flow to remove all solvent. The leftover residue underwent a three-fold extraction with dichloromethane and water (6 ml of dichloromethane + 6 ml of water). The extraction was performed under vortexing for 1 minute. The three dichloromethane fractions were then mixed together, and dried using a rotary evaporator. The amount of lignin contained in the sample corresponds to the weight of the dried dichloromethane extract minus the weight of non volatile ethanol extractives. The total weight of lignin components in the selected liquid phase can be calculated with a simple proportion, knowing the volume of the sample analyzed and the total volume of the liquid phase.

Determination of total weight of acid insoluble lignin (AIL) in lignocellulosic biomass

Raw (solid) lignocellulosic biomass was finely grounded (2 mm particles for herbaceous materials / 0.5 mm particles for woody material) and subjected to two consecutives extractions, first with pure water, then with pure ethanol, using a Soxhlet extractor. The recovered solid was dried overnight at 60 °C, and then at 105 °C for one hour. The extractives-free material obtained was then subjected to a strong acid hydrolysis to measure the content of Klason lignin (acid insoluble lignin). Dried samples were treated with 72% (w/w) sulfuric acid at 30 °C for 1 hour, and then the solutions were diluted with deionized water to achieve 4% (w/w) of sulfuric acid concentration. Diluted samples were autoclaved at 121 °C for 1 hour. The hydrolyzates were filtered through fritted ceramic funnels, and the Klason lignin content was determined as the weight of the acid insoluble residue.

Acid insoluble lignin (Klason lignin) content in the extractives-free material was calculated using the formula below: g (W _AIL )

^^e tractives freeC ?) = * 100% lOOgDM DM extractives free wherein

AIL = acid insoluble lignin [g / 100g DM]

WAIL = weight of AIL after drying at 105 °C [g] DM = dry matter [g]

Lignin content in an “as received” sample can be calculated as follows:

_{T f} g ^ _T (100 — Extractives)

Lignin _as received ^— Lignin _{eX(:raC(:ives} f _ree * loo

“As received” in this calculation refers to the content of lignin per biomass with extractives. Extractives may be removed from the biomass prior to further processing and typically include waxes, oils, free sugars.

Determination of total weight of lignin monomers

A liquid fraction as obtained after reacting a lignocellulosic biomass with a composition as provided herein was separated from the pulp by centrifugation (8000 rpm, 10 min). The liquid was then filtered using glass fiber filters (pore size 1 pm). When two liquid phases were present (organic and aqueous phase), these were separated using a separating funnel.

A sample of the selected liquid phase (~1 ml) was dried under nitrogen flow to remove all solvent. The leftover residue underwent a three-fold extraction with dichloromethane and water (1 ml of dichloromethane + 1 ml of water). The extraction was performed under vortexing for 1 minute. The three dichloromethane fractions were then mixed together, and a sample is taken for subsequent GC analysis.

A weighed amount of 2-isopropylphenol was added to the sample as an internal standard.

GC analysis was performed using a Thermo Fisher ScientificT race GC Ultra equipped with a Rxi-5Sil MS column and a flame ionization detector (FID). The following operating conditions were used: injection temperature 280 °C, column temperature program: 40 °C (1 min), 2 °C/min to 150 °C, 5 °C/min to 240 °C, 30 °C/min to 300 °C (15 min), detection temperature of 305 °C. Response factors for the different products are determined by calibration with commercial standards or via ECN-based calculation, i.e. based on the Effective Carbon Number Theory.

Identification of the monomers may be performed via GC-MS, using a Thermo Fisher Scientific Trace 1310 equipped with a Rxi-5Sil MS column and an ISQ QD Mass Spectroscopy detector. The following operating conditions are used: injection temperature of 280 °C, column temperature program: 40 °C (1 min), 10 °C/min to 300 °C (5 min), detection temperature of 310 °C.

Determination of average molecular weight The following procedure may be followed to determine average molecular weight of obtained fractions and components.

A sample of a liquid phase (~5 ml) obtained after reacting a lignocellulosic biomass with a composition as provided herein is separated from the pulp by centrifugation (8000 rpm, 10 min). The liquid is then filtered using glass fiber filters (pore size 1 pm). When two liquid phases are present (organic and aqueous phase), these are separated using a separating funnel.

The liquid phase sample is dried under nitrogen flow to remove solvent. The remaining residue undergoes a three-fold extraction with dichloromethane and water (6 ml of dichloromethane + 6 ml of water). The extraction is performed under vortexing for 1 minute. The three dichloromethane fractions are then mixed together, and dried using a rotary evaporator. The extracted lignin is then dissolved in tetrahydrofuran to a concentration of 5 mg/ml. A sample is taken and subsequently filtered through a 0.2 pm polytetrafluoroethylene (PTFE) filter.

Gel permeation chromatography analysis may be performed using a Viscotek GPCmax, Model: VE 2001 equipped with TETRA detector (TDA 305 + UV 2600), wherein the Viscotek 305 TDA (Triple Detector Array) detector contains a refractometer (Rl), viscometer (IV = intrinsic viscosity) and light scattering detector (RALS + LALS), or similar equipment. Columns for use in the gel permeation chromatography analysis are well known to a skilled person and may include, but is are not limited to, the following exemplary columns: Viscotek column CLM3041 (LC5000L, mixed, medium, Org, particle size 10 pm, with effective molecular range up to 4M Da) with 50 cm guard column; Agilent (PN PL1110-6520 (PLgel 5 pm, 100 A pore size, 300 x 7.5 mm)) with guard column (Agilent PL1117-1800, 50x7.5mm, which is PolarGel-M column with particle size 8pm and resolving range up to 2M Da; Malvern (CLM3000 T1000 (Org GPC/SEC Col; 6, 1,500-50 Da), CLM3001 T2000 (Org GPC/SEC Col 6, 5,000-150 Da), CLM3002 T2500 (Org GPC/SEC Col 6, 20,000-300 Da),CLM3003 T3000 (Org GPC/SEC Col 6, 70,000-500 Da), CLM3004 T4000 (Org GPC/SEC Col 7, 400,000-1 ,500 Da) with CLM3008 (TGuard 8 guard column)); or Agilent (PL1110-6115 (7.5x300 mm x 10 pm 50 A, up to 1 ,500 Da), PL1110-6320 (7.5x300 mm x 3 pm 100 A, up to 5,000 Da), PL1110-6120 (7.5x300 mm x 10 pm 100 A, up to 5,000 Da), PL1110-6520 (7.5x300 mm x 5 pm 100 A, up to 5,000 Da), PL1013-2120 (PL Rapide F, 10.0 x 100 mm, 6 pm, up to 3,300 Da), PL1113- 3120 (PL Rapide F, 7.5 x 150 mm, 6 pm, up to 3,300 Da). As solvent tetrahydrofuran ³99.5% stabilized with BHT (250 ppm), (AnalaR NORMAPUR® ACS, Reag. Ph. Eur. analytical reagent) may be used. As a standard for the analyses, PL2010-0105 (PS kit S- L2-10, 10 x 0.5 g with the MW of 1200 Da and 2500 Da) may be used. Analyses may be performed with THF as a mobile phase at a flowrate of 1ml/min at 40 °C, with injection volume of 50 pl_, and analysis time varying depending on the column used.

Determination of the amount of carbohydrates

The recovery of xylan (RC5) and glucan (RC6) in the pulp derived from lignocellulosic material as provided herein is defined as the amount of saccharide measured in the pulp divided by the amount of the same saccharide that was present in the biomass initially applied in a process.

Pulp material remaining after reacting a lignocellulosic biomass with a composition as provided herein, was subjected to a strong acid hydrolysis to determine the content of saccharides remaining in this pulp. Dried samples thereof were treated with 72% (w/w) sulfuric acid at 30 °C for 1 h, and then the solutions were diluted with deionized water to achieve 4% (w/w) of sulfuric acid concentration. Diluted samples were autoclaved at 121°C for 1 h. The hydrolyzates were filtered through fritted ceramic funnels. The hydrolyzates were analyzed for carbohydrates using High Performance Liquid Chromatography (Agilent 1200 series). A Hi Plex-H column (Biorad) and refractive index detector (RID) were used to determine the concentrations of glucose, xylose, and arabinose at 65 °C using 0.005M H ₂ SO ₄ as the mobile phase (eluent) with a flow rate of 0.6 ml/min. Equations below summarize the calculations made for the carbohydrates content.

Carbohydrates( 100 wherein

C _anhydro = concentration of the carbohydrates converted into their polymeric form (glucose in form of glucan, etc.) using an anhydro correction (0.88 for pentoses and 0.90 for hexoses) also corrected for any degradation that may have occurred during the dilute-acid step of the hydrolysis according to methodology well known in the art (e.g. by using a recovery factor calculated from replicates enriched with known concentrations of the carbohydrates analyzed) [g/l]

V _hydrolysate = volume of the hydrolysate [ml]

DM = dry matter [g] Example 1

Example 1 illustrates a process according to the invention as applied on hardwood. Birch sawdust (Betula pendula, obtained from Centre Alphonse de Marbaix, Corroy-le-Grand, Belgium) was applied as the lignocellulosic starting material. The birch sawdust was milled and sieved to obtain particles smaller than 2 mm, and 3 g thereof was added into a 300 ml stainless steel batch reactor (Parr Instruments Co.) and mixed with a composition consisting of methanol (120 ml) and sodium dithionite (1 g). The ratio of solvent to biomass was 40 ml:1g; the weight ratio of sodium dithionite to biomass was 1:3.

The reactor was sealed, flushed with an inert gas and pressured under an initial gas pressure of 30 bar (3 MPa) at ambient temperature. The mixture in the reactor was stirred and the temperature of the reactor was increased to 250 °C (5 °C per minute), at which the pressure reached about 140 bar (about 14 MPa). The reaction was carried out for 3 hours at 250 °C.

In a first example (IE1), the reaction was carried out in the presence of hydrogen gas. In a second example (IE2), the reaction was carried out in the presence of nitrogen gas. No catalyst was added during both reactions.

Control experiments were also performed in which no reducing agent was added during the reaction. For this, comparative examples 1 and 2 (CE1 and CE2) were carried out in the same manner as examples 1 (IE1) and 2 (IE2), respectively, with the difference that no sodium dithionite was added during the reaction.

After the reaction, the liquid /organic phase was isolated from the pulp by centrifugation (8000 rpm, 10 min). The liquid phase was then filtered using glass fiber filters (pore size 1 pm), and treated as indicated above in order to determine the total weight of lignin components obtained. The total weight of lignin components in the liquid phase was then calculated with a simple proportion, taking into account the volume of the sample analyzed and the total volume of the liquid phase.

Total weight of acid insoluble lignin (AIL) as present in the lignocellulosic biomass initially introduced in the reactor was determined by applying the procedure as explained above.

The yield of delignification (YD) was determined as the ratio between the total weight of lignin components in the liquid phase and the total weight of acid insoluble lignin (AIL) that was present in the initial biomass.

In order to determine the total weight of lignin monomers obtained, a sample of the liquid phase (~1 ml) was taken and treated by applying the procedure as explained above. The lignin monomer yield (YM) was determined as the ratio between the total weight of lignin monomer in the liquid phase determined via GC-FID and the total weight of acid insoluble lignin (AIL) that was present in the initial biomass.

Table 1 summarizes the reaction conditions and reports the delignifi cation yield (Y _D ) and the lignin monomer yield (YM) as obtained for the different experiments.

Table 1

The experiments carried out using sodium dithionite as reducing agent (IE1 and IE2) allow to obtain high delignifi cation yields (about 70%) and considerable yields of lignin monomer components (about 12-13%), even if the reactions were carried out in the absence of a catalyst. Moreover, the results show that the obtained yields are independent of the nature of the gas phase: similar results are obtained when hydrogen or nitrogen are used in the gas phase. The results confirm that use of hydrogen gas can advantageously be omitted in a process according to the invention.

For comparison, the present invention allows to obtain delignification yields similar to those reported in the prior art (see Van den Bosch et al. 2015: Energy & Environmental Science, Vol. 8, pp. 1748-1763, and Van den Bosch et al. 2017: Green Chemistry Vol. 19, pp. 3313-33267) for treating lignocellulosic biomass through catalytic organosolv fractionation. While the lignin monomers yields may be higher for reactions reported in this prior art, it is noted that this prior art has the important disadvantage of needing a catalyst to arrive at the reported yields.

Example 2

Example 2 provides different examples of processes according to the invention carried out under different reaction conditions and as applied to birch ( Betula pendula).

Birch sawdust (obtained from Centre Alphonse de Marbaix, Corroy-le-Grand, Belgium) (2 mm particles) was prepared in a same way as explained in example 1 and contacted with a composition consisting of a lower alcohol and a reducing agent (sodium dithionite). The reaction was carried out in a same manner as explained in example 1 using the reaction conditions as listed in Table 2. In the experiments of example 2, the reactor was flushed and pressurized using nitrogen gas. Table 2 lists the delignifi cation yield (YD) and the lignin monomer yield (YM) obtained for the different experiments, as determined in a same manner as explained above in example 1

TABLE 2

Example 3

Example 3 is another example of a process according to the invention as applied on hardwood biomass, wherein the hardwood is contacted with a composition wherein the solvent is a mixture of an organic solvent and water. Birch sawdust (Betula pendula, obtained from Centre Alphonse de Marbaix, Corroy-le- Grand, Belgium) was prepared in a same manner as explained in example 1 added into a 300 ml stainless steel batch reactor (Parr Instruments Co.) and mixed with a composition consisting of a butanohwater mixture (volume ratio of 1 : 1 - in the control experiment CE5 no butanol was added) and sodium dithionite as reducing agent (experiments with concentrations of 0.5 g, 1 g or 1.67 g). In the control experiment CE4 no reducing agent was added. In all listed experiments the biomass fed to the reactor comprised 25 g/l. In experiment IE18 no water was added.

The reactor was sealed, flushed and pressured with nitrogen under an initial gas pressure of 0 bar (see experiment IE17) or 30 bar (3 MPa) (see all other listed experiments) at ambient temperature. The mixture in the reactor was stirred and the temperature of the reactor was increased in order to read about 50 bar (about 5 MPa). Table 3 summarizes the reaction conditions applied in the various experiments. The reactions of the different experiments were carried out in the absence of a catalyst and at the indicated temperatures and for the indicated times. Table 3

After each reaction, lignin components and saccharide components were isolated and recovered. Yield of delignifi cation (YD), yield of lignin monomers (YM), and yield of specific unsaturated lignin monomers propenylsyringol and propenylguaiacol for the various experiments were determined using the test methods as explained above and are reported in Table 4. Table 4 further lists the yield obtained for specific carbohydrate components (glucan and xylan) as determined using the test methods as explained above. In Table 4, YPEG stands for yield of propenylguaiacol and YRES stands for yield of propenylsyringol, RC5 stands for recovery of xylan, RC6 stands for recovery of glucan, “nd” stands for “not detected”.

Table 4

For comparison, Van den Bosch et al. (2015) report for the treatment of lignocellulosic biomass through catalytic organosolv fractionation under similar reaction conditions (i.e. particles smaller than 2 mm of birch sawdust ( Betula pendula) treated with methanol in the presence of a ruthenium catalyst for 3 hours at 250°C, biomass feed of 50 g/L and initial hydrogen gas pressure at RT of 30 bar), a delignification yield (YD) of 93%, a lignin monomer yield Y _M of 50%, a yield of propylguaiacol and of propylsyringol of 10 and 32% respectively, a yield of propenylguaiacol and propenylsyringol of 0 and 2% respectively, 56% xylan recovery and 95% glucan recovery. Hence, the present process allows to recover unsaturated lignin monomers in higher amounts than reported in this prior art.

Although lignin monomer yield is higher when a catalytic system is adopted, the experiments carried out according to the invention illustrate that high delignification yields and considerable yields of lignin monomer components can be obtained even if the reactions were carried out in the absence of a catalyst. In addition, a process according to the invention allows recovering lignin components including unsaturated lignin monomers, such as propenylguaiacol; propenylsyringol as well as carbohydrate components such as xylan (C5 saccharide) and glucan (C6 saccharide).

Example 4

Example 4 provides different examples of processes according to the invention carried out under different reaction conditions and as applied to birch ( Betula pendula). In this example 4, a number of the experiments as disclosed in example 2 above where repeated and a number of additional experiments under different reaction conditions were added.

Birch sawdust (Betula pendula, collected in Belgium) (2 mm particles) was prepared in a same way as explained in example 1 and contacted with a composition consisting of a lower alcohol and a reducing agent (sodium dithionite). The reaction was carried out in a same manner as explained in example 1 using the reaction conditions as listed in Table 5. In the experiments of example 4, the reactor was flushed and pressurized using nitrogen gas. Table 5 lists the delignifi cation yield (YD) and the lignin monomer yield (YM) obtained for the different experiments, as determined according to the above given test methods. In Table 5, “nd” stands for “not determined”.

TABLE 5

A maximum yield of delignifi cation (YD) and a maximum yield of phenolic monomers (YM) of 89% (IE21) and nearly 17% (IE22), respectively, were obtained. This constitutes proof of the ability of the present process to achieve considerable delignifi cation and lignin monomers production in absence of a heterogeneous catalyst and hydrogen gas.

Examples 5 to 7

In examples 5 to 7 the following test methods were used.

Test Methods

Determination of non-volatile water and ethanol extractives Raw (solid) biomass was finely grounded (2 mm particles for herbaceous materials / 0.5 mm particles for woody material) and subjected to two consecutive extractions, first with pure water, then with pure ethanol, using a Soxhlet extractor. Each extraction was (conventionally) carried out for 10 hours, with 4-5 siphon cycles per hour (siphon cycle = total reflux of the solvent). The water and ethanol extracts were collected separately and dried at 60 °C overnight, then at 105 °C for 1 hour. The dried residues were weighed to determine the amount of non-volatile water extractives and non-volatile ethanol extractives.

Determination of total weight of lignin components

After contacting a lignocellulosic biomass with a composition as provided in the invention, a liquid fraction as obtained was separated from the pulp by centrifugation (8000 rpm, 10 min). The pulp was subjected to consecutive washings: first with the organic solvent employed during the reaction, then with water, before being dried to constant weight at 60 °C. The organic solvent from the washing was added to the liquid fraction. The water from the washing was added to the liquid fraction only when water was already contained in the initial reaction composition. The liquid fraction was then filtered using glass fiber filters (pore size 1 pm). When two liquid phases were present (organic and aqueous phase), these were separated using a separating funnel.

A sample of the selected liquid phase (~5 ml) was dried under nitrogen flow to remove all solvent. The leftover residue underwent a three-fold extraction with dichloromethane and water (6 ml of dichloromethane + 6 ml of water). Each extraction was performed under vortexing for 1 minute. The three dichloromethane fractions were then mixed together, and dried using a rotary evaporator to obtain a viscous red-brown oil. The amount of lignin contained in the sample corresponds to the weight of the dried dichloromethane extract minus the weight of non-volatile ethanol extractives (contained in the sample). The total weight of lignin components in the selected liquid phase can be calculated with a simple proportion, knowing the volume of the sample analyzed and the total volume of the liquid phase. The amount of extractives contained in a sample will be proportional to its the volume. Namely, a sample of 5 ml_ will contain an amount of extractives equal to: (5 ml_ / total volume) * total weight of non-volatile ethanol extractives. This is what is subtracted from the dried dichloromethane extract. This procedure corresponds to the procedure given above for examples 1 to 4.

Determination of total weight of acid insoluble lignin (AIL) in lignocellulosic biomass

Raw (solid) lignocellulosic biomass was finely grounded (2 mm particles for herbaceous materials / 0.5 mm particles for woody material) and subjected to two consecutives extractions, first with pure water, then with pure ethanol, using a Soxhlet extractor. Each extraction was carried out for 10 hours, with 4-5 siphon cycles per hour (siphon cycle = total reflux of the solvent). The recovered solid was dried overnight at 60 °C, and then at 105 °C for one hour. The extractives-free material obtained was then subjected to a strong acid hydrolysis to measure the content of Klason lignin (acid insoluble lignin). Dried samples were treated with 72% (w/w) sulfuric acid at 30 °C for 1 hour (for herbaceous biomass) or 2 hours (for woody biomass), and then the solutions were diluted with deionized water to achieve 4% (w/w) of sulfuric acid concentration. Diluted samples were autoclaved at 121 °C for 1 hour.

The hydrolyzates were filtered through pre-weighed fritted ceramic funnels. The funnels with the acid insoluble residues were dried overnight at 105 °C prior to weighing them. Then, the funnels with the dried residues were calcinated in a furnace at 400 °C and the weight of the residual ashes was determined. Finally, the Klason lignin content was determined as the weight of the dried acid insoluble residue, minus the weight of residual ashes.

When calculating the Klason lignin content, the above-described determination of the residual ash content is taken into consideration when starting from herbaceous biomass materials. The above-described determination of the residual ash content may or may not be applied when starting from woody materials (hardwood/softwood), since in the case of woody materials effects of ash content on the total weight of acid insoluble lignin are negligible.

Acid insoluble lignin (Klason lignin) content in the extractives-free material was calculated using the formula below: g (W _AIL )

^^e tractives freeC * 100% lOOgDM) = DM extractives free wherein

AIL = acid insoluble lignin [g / 100g DM]

WAIL = weight of AIL after drying at 105 °C [g]

DM = dry matter [g]

Lignin content in an “as received” sample can be calculated as follows:

_{T f} g ^ _T (100 — Extractives)

Lignin _as received ^— Lignin _eX(; ractives free * 100

“As received” in this calculation refers to the content of lignin per biomass with extractives. Extractives may be removed from the biomass prior to further processing and typically include waxes, oils, free sugars. include waxes, oils, free sugars. Determination of total weight of lignin monomers

A liquid fraction as obtained after reacting a lignocellulosic biomass with a composition as provided herein was separated from the pulp by centrifugation (8000 rpm, 10 min). The pulp was subjected to consecutive washings: first with the organic solvent employed during the reaction, then with water, before being dried to constant weight at 60 °C. The organic solvent from the washing was added to the liquid fraction. The water from the washing was added to the liquid fraction only when water was already contained in the initial reaction composition. The liquid was then filtered using glass fiber filters (pore size 1 pm). When two liquid phases were present (organic and aqueous phase), these were separated using a separating funnel.

A sample of the selected liquid phase (~1 ml) was dried under nitrogen flow to remove all solvent. The leftover residue underwent a three-fold extraction with dichloromethane and water (1 ml of dichloromethane + 1 ml of water). Each extraction was performed under vortexing for 1 minute. The three dichloromethane fractions were then mixed together, and a sample was taken for subsequent GC analysis.

A weighed amount of 2-isopropylphenol was added to the sample as an internal standard.

GC analysis was performed using a Thermo Fisher ScientificT race GC Ultra equipped with a Rxi-5Sil MS column and a flame ionization detector (FID). The following operating conditions were used: injection temperature 280 °C, column temperature program: 40 °C (1 min), 2 °C/min to 150 °C, 5 °C/min to 240 °C, 30 °C/min to 300 °C (15 min), detection temperature of 305 °C. Response factors for the different products are determined by calibration with commercial standards or via calculations based on the Effective Carbon Number Theory.

Identification of the monomers may be performed via GC-MS, using a Thermo Fisher Scientific Trace 1310 equipped with a Rxi-5Sil MS column and an ISQ QD Mass Spectroscopy detector. The following operating conditions are used: injection temperature of 280 °C, column temperature program: 40 °C (1 min), 10 °C/min to 300 °C (5 min), detection temperature of 310 °C.

Determination of average molecular weight

A liquid fraction as obtained after reacting a lignocellulosic biomass with a composition as provided herein was separated from the pulp by centrifugation (8000 rpm, 10 min). The pulp was subjected to consecutive washings: first with the organic solvent employed during the reaction, then with water, before being dried to constant weight at 60 °C. The organic solvent from the washing was added to the liquid fraction. The water from the washing was added to the liquid fraction only when water was already contained in the initial reaction composition. The liquid was then filtered using glass fiber filters (pore size 1 pm). When two liquid phases were present (organic and aqueous phase), these were separated using a separating funnel.

A sample of the selected liquid phase (~5 ml) was dried under nitrogen flow to remove all solvent. The remaining residue underwent a three-fold extraction with dichloromethane and water (6 ml of dichloromethane + 6 ml of water). The extraction was performed under vortexing for 1 minute. The three dichloromethane fractions were then mixed together, and dried using a rotary evaporator. The extracted lignin was then dissolved in tetrahydrofuran to a concentration of 5 mg/ml. A sample was taken and subsequently filtered through a 0.2 pm polytetrafluoroethylene (PTFE) filter. Gel permeation chromatography analysis was performed at 40 °C, using tetrahydrofuran as a solvent (flowrate: 1 ml/min) on a Waters E2695 equipped with an Agilent PL Gel column (Mixed E, 3 pm) and a Waters 2998 Photodiode array detector (UV detection at 280 nm). Polystyrene standards were employed to create calibration curves. The number average molecular weight (M _n ), the weight average molecular weight (M _w ) and the polydispersity index of di molecular weight distribution (PDI) were computed using the formulas below.

M, PDI =

M, wherein

Ni is the absorbance measured for molecules possessing a weight M, (proportional to the number of molecules possessing a weight Mi) [a.u.] (absorbance units).

Determination of the amount of carbohydrates The recovery of xylan (RC5) and glucan (RC6) in the pulp derived from lignocellulosic material as provided herein is defined as the amount of saccharide measured in the pulp divided by the amount of the same saccharide that was present in the biomass initially applied in a process. ^m glucan,pulp

RC 6 mglucan, biomass

Pulp material remaining after reacting a lignocellulosic biomass with a composition as provided herein, was subjected to a strong acid hydrolysis to determine the content of saccharides remaining in this pulp. Dried samples thereof were treated with 72% (w/w) sulfuric acid at 30 °C for 2 h, and then the solutions were diluted with deionized water to achieve 4% (w/w) of sulfuric acid concentration. Diluted samples were autoclaved at 121°C for 1 h. The hydrolyzates were filtered through fritted ceramic funnels. The hydrolyzates were analyzed for carbohydrates using High Performance Liquid Chromatography (Agilent 1200 series). A Hi Plex-H column (Biorad) and refractive index detector (RID) were used to determine the concentrations of glucose, xylose, and arabinose at 65 °C using 0.005M H ₂ SO ₄ as the mobile phase (eluent) with a flow rate of 0.6 ml/min. Equations below summarize the calculations made for the carbohydrates content.

Carbohydrates( wherein

C _anhydro = concentration of the carbohydrates converted into their polymeric form (glucose in form of glucan, etc.) using an anhydro correction (0.88 for pentoses and 0.90 for hexoses) also corrected for any degradation that may have occurred during the dilute-acid step of the hydrolysis according to methodology well known in the art (e.g. by using a recovery factor calculated from replicates enriched with known concentrations of the carbohydrates analyzed) [g/l]

V _hydroiysate = volume of the hydrolysate [ml]

DM = dry matter [g]

Example 5

Example 5 provides different examples of processes according to the invention as applied on hardwood biomass, wherein the hardwood is contacted with a composition wherein the solvent is a mixture of an organic solvent and water. In this example 5, a number of the experiments as disclosed in example 3 above were repeated with a higher number of samples, and a number of additional experiments were performed.

Birch sawdust (Betula pendula, collected in Belgium) was prepared in the same manner as explained in example 1, added into a 300 ml stainless steel batch reactor (Parr Instruments Co.) and mixed with a composition consisting of a butanokwater mixture (volume ratio of 1 : 1 - in the control experiment CE8 no butanol was added) and sodium dithionite as reducing agent (experiments with concentrations of reducing agent in a range between 1.6 g/l and 16.7 g/l - in the control experiment CE7 no reducing agent was added). In all listed experiments the biomass was fed to the reactor at concentrations comprised between 25 g/l and 100 g/l.

The reactor was sealed, flushed and pressured with nitrogen under an initial gas pressure of 0 bar (see experiment IE39) or 30 bar (3 MPa) (see all other listed experiments) at ambient temperature. The mixture in the reactor was stirred (750 rpm) and the temperature of the reactor was increased up to the chosen setpoint, between 175 °C and 250 °C - in the control experiment CE6 a temperature of 150 °C was applied . The mixture was left to react for a duration between 0.75 hours and 6 hours - in the control experiment CE9 a duration of 0 hours was applied (i.e. the reaction was halted as soon as the temperature reached the setpoint). Table 6 summarizes the reaction conditions applied in the various experiments. The reactions of the different experiments were carried out in the absence of a catalyst and at the indicated temperatures and for the indicated times.

Table 6

After each reaction, lignin components and saccharide components were isolated and recovered. The yield of delignifi cation (YD), the yield of lignin monomers (YM), and the yield of specific unsaturated lignin monomers (propenylsyringol and propenylguaiacol) for the various experiments were determined using the test methods as explained above (and are reported in Table 7. Table 7 further lists the yield obtained for specific carbohydrate components (glucan and xylan) as determined using the test methods as explained above. In Table 7, YREG stands for yield of propenylguaiacol and YRES stands for yield of propenylsyringol, RC5 stands for recovery of xylan, RC6 stands for recovery of glucan, “nd” stands for “not determined”.

Table 7

The adoption of process configurations involving the treatment of birch sawdust with a composition consisting of a mixture of butanol and water led to high yields of delignification (up to 99% for IE36) and lignin monomers (e.g. up to about 21% for IE38). In addition, high selectivities for 4-propenyl guaiacol and 4-propenyl syringol were found, with a maximum yield for 4-propenyl guaiacol of about 3% (see IE38) and for 4-propenyl syringol of 14% (IE45). Moreover, near complete preservation of glucan was observed for most configurations, while xylan was removed, leading to the recovery of a pulp with a high purity of cellulose.

For comparison, Van den Bosch et al. (2015) report for the treatment of lignocellulosic biomass through catalytic organosolv fractionation under similar reaction conditions (i.e. particles smaller than 2 mm of birch sawdust ( Betula pendula) treated with methanol in the presence of a ruthenium catalyst for 3 hours at 250°C, biomass feed of 50 g/L and initial hydrogen gas pressure at RT of 30 bar), a delignification yield (YD) of 93%, a lignin monomer yield YM of 50%, a yield of propylguaiacol and of propylsyringol of 10 and 32% respectively, a yield of propenylguaiacol (YPEG) and propenylsyringol (YPE _S ) of 0 and 2% respectively, 56% xylan recovery (RC5) and 95% glucan recovery (RC6).

Hence, the present process allows to recover unsaturated lignin monomers in higher amounts than reported in this prior art. In other words, while good yield of delignification and recoveries for polysaccharides are obtained for the present invention and for this prior art, the present invention allows to recover unsaturated lignin monomers in higher amounts than reported in this prior art, with high selectivity for 4-propenylguaiacol and 4-propenylsyringol.

Although lignin monomer yield is higher when a catalytic system is adopted, the experiments carried out according to the invention illustrate that high delignification yields and considerable yields of lignin monomer components can be obtained even if the reactions were carried out in the absence of a catalyst. In addition, a process according to the invention allows recovering lignin components including unsaturated lignin monomers, such as propenylguaiacol; propenylsyringol as well as carbohydrate components such as xylan (C5 saccharide) and glucan (C6 saccharide).

The above given examples demonstrate that by carrying out the process of the invention, a simultaneous isolation/fractionation and depolymerization of lignin can be obtained directly starting from raw lignocellulosic biomass and in absence of heterogeneous catalysts and hydrogen gas. To that end, the process involves the combined use of a reducing agent, in particular a sulphur-based reducing agent, and an organic solvent, optionally in a mixture with water.

Characterization of the lignin fractions

Average molecular weight of the extracted lignin fractions obtained in example 5 was determined following the test method described above. Table 8 reports the number average molecular weight (M _n ), the weight average molecular weight (M _w ) and the polydispersity index (PDI = Mw/Mn) determined for the lignin oil obtained from the performed experiments.

Table 8

From Table 8, it can be noted that the present invention provides a process enabling to obtain lignin components of low molecular weight. The average molecular weight of the lignin oil resulting from the experiments presented above is in general lower than 2000 g/mol. Figures 1 to 6 represent the molecular weight distribution profiles as determined by gel permeation chromatograghy (see test methods above) of the lignin oil obtained for various experiments reported in this example 5. The figures 1 to 6 represent the MWD profile for experiments that were grouped per condition, i.e. each figure shows the MWD profiles obtained when changing one experimental condition. Some curves are repeated in multiple figures to facilitate comparisons. The MWD curves have been represented in the figures one above the other (i.e. not superimposed on one another) to facilitate representation of the results. All represented GPC profiles have been shifted up (away from the baseline of the X-axis) to facilitate their representation.

Figure 1 shows MWD profiles of lignin oil obtained from certain experiments that were carried out at different weight ratios NaaSaC : biomass (IE34, IE35, IE36 and CE7).

Figure 2 shows the MWD profile of lignin oil obtained from certain experiments that were carried out under different durations (IE35, IE37, IE38, CE9).

Figure 3 shows the MWD profile of lignin oil obtained from certain experiments that were carried out at different initial nitrogen pressures (IE36, IE39).

Figure 4 shows the MWD profile of lignin oil obtained from certain experiments that were carried out using different solvent compositions (IE35, IE40, IE41 and CE8).

Figure 5 shows the MWD profile of lignin oil obtained from certain experiments that were carried out at different temperatures (IE36, IE42, IE43, IE44 and CE6).

Figure 6 shows the MWD profile of lignin oil obtained from certain experiments that were carried out at different concentrations of biomass (IE35, IE45 and IE46).

The molecular weight distribution curves shown in Figures 1 to 6 for the various experiments illustrate that processing birch sawdust under the conditions in accordance with the present process allows to achieve substantial depolymerization of the isolated lignin fraction.

The present examples 2, 3, 4 and 5 illustrate that the process according to the invention is able to fractionate solid lignocellulosic biomass (i.e. raw biomass that was not pre treated chemically) and convert (depolymerise) native lignin into low molecular weight phenolics within one reaction step by the combined action in that reaction step of a sulphur-based reducing agent (in these examples sodium dithionite) and an organic solvent (examples 2 and 4) or of a sulphur-based reducing agent (in these examples sodium dithionite) and an organic solvent in mixture with water (examples 3 and 5).

Example 6

Example 6 is another example of a process according to the invention as applied on herbaceous or softwood biomass, wherein the biomass is contacted with a composition wherein the solvent is provided as a mixture of an organic solvent and water.

Miscanthus sawdust (Miscanthus giganteus, obtained from Centre Alphonse de Marbaix, Corroy-le-Grand, Belgium), wheat straw sawdust (Triticum aestivum, obtained from Centre Alphonse de Marbaix, Corroy-le-Grand, Belgium) and spruce sawdust (Picea abies, collected in Belgium) were prepared in the same manner as explained in example 1 , added into a 300 ml stainless steel batch reactor (Parr Instruments Co.) and mixed with a composition consisting of a butanol:water mixture (volume ratio of 1 :1) and sodium dithionite as reducing agent (the concentration of reducing agent was 4.2 g/l for all experiments). In all listed experiments the raw biomass was fed to the reactor at a concentration of 25 g/l.

The reactor was sealed, flushed and pressured with nitrogen under an initial gas pressure of 30 bar (3 MPa) at ambient temperature. The mixture in the reactor was stirred (750 rpm) and the temperature of the reactor was increased up to 200 °C. The mixture was then left to react for 3 hours. After each reaction, lignin components and saccharide components were isolated and recovered. The yield of delignifi cation (YD), the yield of lignin monomers (YM), and the yield of specific unsaturated lignin monomers (propenylsyringol and propenylguaiacol) for the various experiments were determined using the test methods as explained above and are reported in Table 9. Table 9 further lists the yield obtained for specific carbohydrate components (glucan and xylan) as determined using the test methods as explained above. In Table 9, YPEG stands for yield of propenylguaiacol and YRES stands for yield of propenylsyringol, RC5 stands for recovery of xylan, RC6 stands for recovery of glucan.

Table 9 The results reported in Table 9 show that the process according to the invention is not only efficient for the treatment of hardwood biomass (see e.g. Examples 2, 3, 4, 5 herein) but can also be applied effectively for the treatment of herbaceous and softwood biomass, hence confirmed process stability and robustness.

For comparison, Van Den Bosch et al. (2015) reported the catalytic organosolv fractionation of miscanthus ( Miscanthus giganteus) and of a mixture of pine and spruce sawdust (treatment with methanol, in the presence of a heterogeneous ruthenium catalyst for 3 hours at 250°C, with biomass feed of 50 g/L and under an initial hydrogen gas pressure at room temperature of 30 bar), and obtained a delignification yield of 56% for miscanthus and 40% for softwood biomass, a lignin monomer yield of 27% for miscanthus and 21% for softwood biomass, but no unsaturated lignin monomers in the products.

Hence, when the process of the invention is applied to herbaceous and softwood biomass, the present process also allows to recover unsaturated lignin monomers in higher amounts than reported in this prior art, with high selectivity for 4-propenyl guaiacol and 4-propenyl syringol.

Therefore, the above experiments carried out in accordance with the present process illustrate that high delignifi cation yields and considerable yields of lignin monomer components can be obtained for herbaceous and softwood biomass types. This is surprising as the present process is carried out in the absence of a catalyst. In particular, the experiments reported in this example 6 demonstrate stability and robustness of the present process which, regardless of the origin of the lignocellulosic biomass, yields a lignin oil with high selectivity for unsaturated lignin monomers and a highly delignified pulp, with almost complete glucan preservation. Characterization of the lignin components

Average molecular weight of the extracted lignin fractions was determined following the test method described above. Table 10 reports the number average molecular weight (M _n ), the weight average molecular weight (M _w ) and the polydispersity index (PDI) determined for the lignin oil obtained from the experiments performed. Table 10

Figure 7 shows the profile for the molecular weight distribution obtained from gel permeation chromatography of the lignin oil obtained from certain experiments carried out with different biomasses (IE47, IE48 and IE49). The molecular weight distributions shown in Figure 7 illustrates that considerable depolymerization of the isolated lignin fractions can be obtained by applying a process according to the invention to lignocellulosic biomass from different origins.

The presence of high molecular weight fragments in the lignin oil becomes more dominant when treating wheat straw (IE48) and spruce sawdust (IE49) as compared to birch (see e.g IE35) and miscanthus sawdust (IE47). It is considered that these differences in lignin depolymerization for lignocellulosic biomass from different sources may be ascribed to nature of the biomass used, e.g. to differences in the content of cleavable b-aryl ether bonds in the lignin structures of these biomass types.

Example 7

Example 7 is another example of a process according to the invention as applied on hardwood biomass, wherein the biomass is contacted with a composition wherein the solvent is a mixture of an organic solvent and water.

Birch sawdust (Betula pendula, collected in Belgium) was prepared in the same manner as explained in example 1, added into a 300 ml stainless steel batch reactor (Parr Instruments Co.) and mixed with a composition consisting of a butanol:water mixture (volume ratio of 1 :1) and a reducing agent.

The reducing agents adopted were sodium thiosulfate (NaaSaCh) or sodium sulfite (NaaSCh). In the control experiment CE10 sodium sulfate (NaaSCU) was employed instead of a reducing agent. The concentration of reducing agent or sodium sulfate was 4.2 g/l for all experiments. In all listed experiments the raw biomass was fed to the reactor at a concentration of 25 g/l.

The reactor was sealed, flushed and pressured with nitrogen under an initial gas pressure of 30 bar (3 MPa) at ambient temperature. The mixture in the reactor was stirred (750 rpm) and the temperature of the reactor was increased up to 200 °C. The mixture was then left to react for 3 hours.

After each reaction, lignin components and saccharide components were isolated and recovered. The yield of delignifi cation (YD), the yield of lignin monomers (YM), and the yield of specific unsaturated lignin monomers (propenylsyringol and propenylguaiacol) for the various experiments were determined using the test methods as explained above and are reported in Table 11. Table 11 further lists the yield obtained for specific carbohydrate components (glucan and xylan) as determined using the test methods as explained above. In Table 11 , YREG stands for yield of propenylguaiacol and YRES stands for yield of propenylsyringol, RC5 stands for recovery of xylan, RC6 stands for recovery of glucan.

Table 11

The results reported in Table 11 show that different sulphur-based reducing agents as defined herein can be employed in a process according to the invention and lead to considerable yields of delignification and lignin monomers, with selectivity for 4- propenylguaiacol and 4-propenyl syringol.

In particular, when using sodium thiosulfate (IE50) and sodium sulfite (IE51) as reducing agent, larger yields of lignin monomers were obtained when compared to the use of sodium sulfate (CE10), proving that the use of efficient reducing agents, is necessary to achieve a satisfactory generation of lignin monomers. In addition, near complete preservation of glucan was found in experiments IE50 and IE51.

Characterization of the lignin components

Average molecular weight of extracted lignin fractions was determined following the test method described above. Table 12 reports the number average molecular weight (M _n ), the weight average molecular weight (M _w ) and the polydispersity index (PDI) determined for lignin oil obtained from the performed experiments.

Table 12

Figure 8 shows the MWD profile as obtained from gel permeation chromatography of lignin oil obtained from experiments carried out for the different experiments (IE50, IE51 and CE10).

The molecular weight distribution data shown for different experiments in Figure 8 and Table 12 illustrate that a more substantial depolymerization of the isolated lignin fractions is obtained with using stronger reducing agents. Indeed, the average molecular weight of the lignin oil was found to diminish following the order: sodium sulfate (CE10), sodium sulfite (IE51), sodium thiosulfate (IE50). With the latter giving a molecular weight distribution almost identical to that observed for the use of sodium dithionite (see e.g. IE36).