EP3880667A1 - Method of forming monomers and furfural from lignocellulose - Google Patents

Abstract

The present disclosure relates to a method of producing monophenolicmonomers and furfural from lignocellulosic biomass beating the biomass in a solvent together with a zeolite based catalyst.

Description

METHOD OF FORMING MONOMERS AND FURFURAL FROM LIGNOCELLULOSE

FIELD OF THE INVENTION

The present disclosure relates to a method of preparing monomers such as

monophenolic monomers and furfural from biomass such as lignocellulose.

Additionally the invention further relates to compositions obtained from the method and fuel obtained by treating the composition.

BACKGROUND

Lignocellulose is the most available source of biomass. Unlike crude oil, the most utilized source for the production of chemicals and fuels, biomass is renewable and “carbon neutral”. Thus, development of methods for biomass valorisation to platform chemicals or fuel precursors are of high importance. Lignocellulose comprises three main components: lignin, cellulose, and hemicellulose. Lignin is an aromatic hetero polymer linked together via C-C and C-0 bonds and mainly derived from three monolignols, coniferyl, p-coumaryl and sinapyl alcohols. Hemicellulose and cellulose both are polysaccharides, but with different structural properties. Cellulose is a crystalline regular polymer consisting of glucose, and hemicellulose is an irregular amorphous polymer comprising C-5 and C-6 sugars. In order to utilize biomass in the most efficient way, it is desirable to transform simultaneously all three components into value added products. Given to the dissimilarity of the structure between cellulose, hemicellulose and lignin, together with the fact that they are cross-linked with each other through covalent bonds, it is a challenging task to transform all three components in one single process. For example, current pulping industry upgrades only the cellulose fibres.

Acid-catalyzed pulping is a promising approach for catalytic fractionation of biomass, since potentially all three components can be transformed into valuable monomeric products. The main obstacle of this approach is the formation of reactive intermediates during the depolymerization of lignin that react to form dimeric, oligomeric and polymeric by-products via C-C bond formation (Figure 1). To avoid the repolymerization of lignin during acid-catalyzed pulping“native” lignin may be isolated using various methods. For example this may be achieved by the addition of formaldehyde, which results in the formation of the acetal of lignin’s 1 ,3 - diols, and prevents formation of reactive benzylic carbocations. The isolated lignin acetal could then be further converted into monomeric products via a hydrogenolysis reaction. Another approach where repolymerization of lignin is circumvented is by stabilization of the reactive aldehyde intermediates, via transformation into acetals by addition of ethylenglycol (Figure lb). Acetal formation with methanol has also been reported, a Rh-catalyzed in situ decarbonylation of reactive aldehydes formed during triflate-catalyzed cleavage of lignin (Figure lb). All mentioned methodologies either utilize a metal or stoichiometric amounts of capping agent, and mainly focus on the conversion of lignin. There is a lack of a simple and additive-free process allowing to simultaneously convert and exploit the three components lignin, cellulose and hemicellulose of biomass.

Considering cellulose and hemicellulose valorisation, various studies reported the conversion of cellulose or xylose and glucose into furfural, 5-hydroxymethylfurfural (5- HMF) or lactic acid (LA). Furfural is industrially produced from lignocellulosic biomass in the presence of sulphuric acid, through hydrolysis and dehydration of pentoses. The production of furfural presents several drawbacks associated to the use of homogeneous acids such as corrosion and the production of large amount of acidic residues. Then investigations for optimizing cellulose conversion and furfural production continue to be of a great interest.

Prior art provides various strategies for degrading lignin into small units or molecules in order to prepare processable lignin derivatives. These strategies include hydrogenation, deoxygenation and acid catalyst hydrolysis. WO201 1003029 relates to a method for catalytic cleavage of carbon-carbon bonds and carbon-oxygen bonds in lignin. US20130025191 relates to a depolymerisation and deoxygenation method where lignin is treated with hydrogen together with a catalyst in an aromatic containing solvent.

SUMMARY OF INVENTION

Considering the disclosure of prior art the object of the present disclosure is to take advantage of the catalytic properties and the pore size of protonic or acidic zeolites for organosolv pulping of biomass and to overcome the drawbacks of prior art. The present disclosure presents a method to stabilize monomers and furfural released from all components: cellulose, hemicellulose and lignin. Indeed, the present zeolite-based solid catalysts have a porous system conferring high surface area and shape and size selectivity together with the possibility of accommodating different metals in its framework giving them acid/base or redox properties. Without being bound by theory the substitution of aluminum for silicon in a silica covalent framework induces a charge unbalance that can be compensated by cation. When this cation is ammonium ion its thermal decomposition produces proton as compensation cation and so protonic zeolite with strong Bronsted sites. Moreover, the thermal stability and easy regeneration of zeolites through calcination step allow to reuse them readily.

Therefore, it is envisioned that zeolite-based catalysts of the present disclosure may convert released monomers such as allylic alcohols and products derived from sugars via transfer hydrogenolysis reactions and dehydration, hampering their bimolecular condensations due to the pore size constraint and diffusion control, avoiding the usage of the trapping agents and transition metals. This methodology also allows to preserve the core structure of the biomass components for example lignin is not modified as in organosolv processes.

In the broadest aspect the present disclosure relates to a method of producing monomers from lignocellulosic biomass by acid-catalyzed fractionation of lignocellulosic biomass, comprising the steps of: a. mixing the lignocellulosic biomass, a zeolite-based solid catalyst, and a solvent; and b. heating the mixture obtained in step a at a temperature of 120°C or higher.

In another aspect the present disclosure relates to a method of producing monomers and / or furfural from biomass comprising the steps of:

o mixing the biomass, a solvent and a zeolite-based solid catalyst forming a first mixture;

o heating the first mixture at a temperature of 120°C or higher but not higher than 300°C to obtain the monomers and/or furfural; and o optionally isolating the obtained monomers and / or furfural wherein the biomass contains lignin, cellulose and/or hemicellulose and wherein the zeolite-based solid catalyst preferably have pores with a diameter of 0.7nm (7A) or smaller but 0.4nm (0.4Ά) or larger.

In yet another aspect the present disclosure relates to a method of producing monomers and / or furfural from biomass comprising the steps of:

o mixing the biomass and a solvent forming a first mixture;

o heating the first mixture at a temperature of 120°C or higher but not higher than 300° C to obtain a solvolysis product;

o bringing the solvolysis product into contact with a zeolite-based solid catalyst forming a second mixture; o heating the second mixture at a temperature of 120°C or higher but not higher than 300° C for a second suitable period of time to form monomers and / or furfural; and

o optionally isolating the obtained monomers and/or furfural; wherein the biomass contains lignin, cellulose and/or hemicellulose and wherein the zeolite-based solid catalyst preferably have pores with a diameter of 0.7nm or smaller but 0.4nm or larger.

In a preferable embodiment of the method of the invention, the zeolite-based solid catalyst possesses a pores system without cavities. In another preferable embodiment of the method, the zeolite-based solid catalyst possesses a nanocrystalline structure. Preferably, in the method of the invention the monomers produced comprise

monophenolic compounds and furfural.

In a further preferable embodiment of the method of the invention, the weight percent of the zeolite-based solid catalyst with respect of the weight of the lignocellulosic biomass or the lignin and/or cellulose containing biomass is 1-50 wt% and preferably 5-25 wt%. Preferably, the solid catalyst is separated from the mixture after completion of the heating or the heating step b of the method of the invention. Preferably, the method of the invention is performed in a stirred batch or a continuous stirred-tank reactor.

In a preferred embodiment of the composition of the invention, the content of furfural is 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, by weight of the composition.

In one embodiment the present disclosure relates to a method according to the present disclosure wherein the mixture such as in step b is heated at a temperature of 120- 250°C, preferably at 150-250°C, and most preferably at 200-240°C.

In another embodiment the mixture such as in step b is heated for 0.1 to 10 h, more preferably for 0.5 to 5h and most preferably for 2 h under a pressure from 1 to 80 bars.

In one embodiment the present disclosure relates to a method according to the present disclosure wherein the zeolite-based solid catalyst contents a trivalent metalloid or metal or mixture thereof, preferably Boron or Aluminum, and most preferably Aluminum. In one embodiment the present disclosure relates to a method according to the present disclosure wherein the zeolite-based solid catalyst presents a framework Si/Al ratio in the range of 7-50, preferably in the range of 10-35.

In another embodiment the present disclosure relates to a method according to the present disclosure wherein the zeolite-based solid catalyst possesses a tridirectional or a bidirectional system of pores, preferably a tridirectional system of pores.

In another embodiment the present disclosure relates to a method according to the present disclosure wherein the zeolite-based solid catalyst possesses a topology of pores with at least 10 membered-ring and preferably 12 membered-ring.

In yet another embodiment the present disclosure relates to a method according to the present disclosure wherein the zeolite-based solid catalyst is beta zeolite.

In one embodiment the present disclosure relates to a method according to the present disclosure wherein the lignocellulosic biomass is hardwood or softwood or a mixture thereof.

In one embodiment the present disclosure relates to a method according to the present disclosure wherein the solvent is a polar solvent, such as methanol, ethanol, 1 -propanol, 2-propanol, 1 -butanol, 2-butanol 1, 4-dioxane or acetonitrile and preferably a mixture of a polar solvent and water wherein the water content is in the range of from 0.5 to 20 % of the total volume of solvent mixture, and most preferably wherein the mixture is a mixture of ethanol and water.

In another aspect the present disclosure relates to a composition derived from wood comprising a mixture of monophenolic compounds and furfural.

In one embodiment the mixture of monophenolic compounds comprises the following monophenolic compounds as its major constituents:

In another embodiment the composition further comprises esters of levulinic acid, and ethers of sugars, and/or 5-hydroxymethylfurfural.

Another aspect of the present disclosure relates to a composition obtainable or obtained by the method according to the present disclosure.

An additional aspect of the present disclosure relates to a fuel obtainable or obtained by hydroprocessing the composition of the present disclosure or a fraction of said compositions.

All embodiments disclosed herein relates to all aspects of the present disclosure unless stated otherwise.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1, a. A schematic illustration of prior art disclosing recondensation reactions during acid-catalyzed pulping b. A schematic illustration of prior art disclosing prevention of recondensation reactions during pulping of biomass (previous reports) c. A schematic illustration of the reaction scheme of the present disclosure.

Figure 2, A schematic illustration of the release of allylic alcohols during organosolv pulping of lignocellulose

Figure 3, A schematic illustration of the reaction of coniferyl alcohol 1 under

organosolv pulping conditions in the presence of beta- 1 zeolite.

Figure 4, Scheme of b-O-4 cleavage of model dimer under organosolv pulping conditions.

Figure 5, Phenylacetaldehyde (12) plotted versus time when 12 was submitted under organosolv pulping conditions in presence of beta- 1 and HY- 1 zeolites.

Figure 6, Schematic scheme of the reaction of phenylacetaldehyde in the presence of zeolite.

Figure 7, Illustrative scheme pathway for lignin depolymerization and allylacohols conversion and stabilization in the presence of beta- 1 zeolite.

Figure 8, Scheme pathway for hemicellulose and cellulose depolymerization in the presence of beta- 1 zeolite. Figure 9, Schematic representation of the location of transformation of components of biomass during zeolite-catalyzed pulping according to the present disclosure.

Figure 10, a) temperature and b) water content dependence of furfural and lignin monomers yield. Yield calculated as: mass of products/mass of lignin. Mass of furfural/ mass of (cellulose + hemicellulose). Reaction conditions: 200 mg of birch sawdust, 50 mg catalyst, Eί0H/¾0 5mL, 200 °C, 2h.

Figure 11 , Scheme and table disclosing reaction conditions and conversion /yield. Figure 12, Uncatalyzed reaction of wood.

Figure 13, framework of a zeolite catalyst, a) framework type FAU (faujasite) viewed along [1 11], b) framework type BEA (beta) viewed along [100].

DETAILED DESCRIPTION OF THE INVENTION

In the present disclosure“biomass” includes, but is not limited to wood, fruits, vegetables, processing waste, chaff, grain, grasses, com, com husks, weeds, aquatic plants, hay, paper, paper products, recycled paper, shell, algae, straw, bark or nut shells, lignocellulosic material and any cellulose and/or lignin containing biological material or material of biological origin. In one embodiment the biomass is

lignocellulose. In one embodiment the biomass is wood, preferably particulate wood such as saw dust or wood chips. The wood may be any kind of wood, hard or soft wood, coniferous tree or broad-leaf tree. In one embodiment the biomass is hard wood or soft wood or a mixture thereof. A non-limiting list of woods would be pine, birch, spruce, maple, ash, mountain ash, redwood, alder, elm, oak and beech. In one embodiment the biomass contains lignin where the chemical structure or chemical composition of the lignin has essentially not been modified. In one embodiment the biomass is organosolv lignin, i.e. lignin obtained from an organosolv process. An advantage of using lignocellulose biomass such as wood is that the method becomes more efficient and provides higher yield of the wanted products. The reason for this is believed to be that isolated lignin or cellulose for example have already been treated in some way and the wanted lignin or cellulose may have formed bonds that are hard to break and the monomers or products that is supposed to be stabilized by the catalyst may already have recondensated or repolymerized.

Organosolv is a pulping technique originating from the early 1930’s while the main development was performed during the late 1980’s where biomass is separated in cellulose and, lignin and hemicellulose. The technique involves contacting a lignocellulosic feedstock such as chipped wood with an aqueous organic solvent at temperatures ranging from 140°C and higher usually not higher than 220°C. This causes hydrolytic depolymerization of alpha aryl-ether links into fragments that are soluble in the organic solvent. Solvents used include acetone, methanol, ethanol, butanol, ethylene glycol, formic acid, and acetic acid. The concentration of the solvent in water may be in the range of from 40 to 80 wt%. Higher boiling solvents may be used and have the advantage that a lower process pressure may be used, on the other hand such solvents are harder to recover. The organosolv process may be a two or more-stage process where the same or different solvents are used in the two stages. A base such as sodium hydroxide may be added, preferably in the second stage and the lignin may be isolated by lowering the pH using any suitable acid. In order to isolate the high molecular weight lignin from hemicellulose in the organosolv process the lignin may be precipitated or the mixture may be filtrated, evaporated, distilled or centrifuged.

In the present disclosure cell parameters or unit cell parameters and other features of the zeolite relating to pore size, cavities and volume are used as defined in https: / / europe.iza-structure.org/ IZA-SC /framework.php?STC=BEA viewed November 11 , 2019 (data last updated July 1, 2007). Figure 13 discloses the framework type FAU (Figure 13a)) and framework type BEA (Figure 13b)) according to said database.

In the present disclosure the term“pore” means an elongated hole or void with an opening.

In the present disclosure pore size, pore diameter and diameter of a pore denotes the same thing and refers to the size determined using nitrogen gas adsorption measured at 77K for pores with sizes up to lOOnm. Pore size or pore diameter presented herein denotes the maximum size of pores constituting at least 90% or preferably at least 95% of the total pore volume. For example, a pore diameter of 0.7nm or 0.7nm or smaller denotes that at least 90% of the total pore volume is constituted by pores having diameters of 0.7nm or smaller. For example, a pore diameter of 0.7nm or smaller but 0.4nm or larger denotes that at least 90% of the total pore volume is constituted by pores having a diameter of 0.7nm or smaller and 0.4nm or larger.

In the present disclosure the term“cavity” means a hole or void having a diameter larger than l . lnm (l lA). In the present disclosure cavity volume, cavity diameter or cavity size denotes the same thing and refers to the size determined using nitrogen gas adsorption measured at 77K for cavities with sizes up to lOOnm.

In the event of a discrepancy between the chemical name of any particular compound and the structural formula thereof, then it is the latter that prevails, unless contradicted by experimental details or unless otherwise is clearly apparent from the context.

The present disclosure provides a straightforward method of depolymerizing lignin direct from the biomass, without having to isolate lignin or cellulose or hemicellulose first. Furthermore, the method may be implemented into the already existing techniques such as the organosolv process. By providing a method that may be conducted in a one pot synthesis or one pot reaction the present disclosure presents a very efficient strategy for preparing furfural and monomers such as phenolic

containing monomers from biomass. An advantage of the present method is that the parameters of the method such as temperature or solvent used may be adjusted in order the increase the yield of furfural or monomers such as phenolic containing monomers or monophenolic monomers.

In the present method lignin first undergoes solvolytic depolymerization and releases reactive allylic alcohols, which afterwards get transformed inside the pores of the present zeolite-based catalyst over Bronsted acid active sites into the stabilized monophenolic products. Moreover, hemicellulose/ cellulose is partially transformed into furfural when in contact with the zeolite-based catalyst. The present disclosure is a first example of a new additive and transition metal-free approach in the stabilization of monomers derived from pulping of biomass.

The method according to the present disclosure relates to treating biomass such as lignocellulosic biomass, lignin, cellulose or hemicellulose by acid-catalyzed

fractionation. The biomass is mixed with a zeolite based solid catalyst and a solvent forming a first mixture which is heated at a temperature of 120°C or higher. This generates an intermediate product, a solvolysis product. In a preferred embodiment the mixture or first mixture is heated at 120-300°C, preferably at 120-25OC, more preferably at 150-25OC, more preferably at 180-240°C, more preferably at 200-240C, more preferably at 200-230°C. When producing monomers from lignin such as monophenolic monomers the mixture or first mixture is preferably heated at 200- 240°C preferably around 220°C. When producing furfural the mixture or first mixture is preferably heated at 180-220°C, preferably at 190-210°C, more preferably around 200°C. The heating may be done for a suitable period of time preferably from 0.1 to lOh, preferably from 0.5 to 5h and more preferably for 2h. Still the time is dependent on the volume of the mixture. A pressure may also be applied during the heating. In one embodiment the pressure is from 1 to 80 bar, preferably from 2 to 50 bar, more preferably from 5 to 20 bar. Applied pressure may shorten the treatment time and may increase the yield. In one embodiment the method is conducted in a sealed container. In another embodiment the method is conducted at atmospheric pressure.

Mixing of the lignocellulosic biomass, the zeolite-based solid catalyst and the solvent may be done in any suitable way using any suitable technique such as stirring or shaking. A stirred batch reactor or a continuous stirred-tank reactor may be used when conducting the present method. The amount zeolite catalyst with respect to the weight percent of the biomass in the mixture is preferably l-50wt% more preferably 5- 25wt%. The pH of the mixture or the first mixture is preferably acidic. In one embodiment the pH is 2-6, preferably 3-5.

In order to stabilize the monomers and furfural and to avoid that the monomers and furfural formed during the method undergo recondensation or repolymerization the zeolite-based solid catalyst needs to have large enough pores to allow the solvolysis products to enter the catalyst but small enough pores to reduce the amount of solvolysis products entering each pore. The zeolite based solid catalyst may be in the form of a powder or particles. Preferably the zeolite-based solid catalyst should be essentially free from any cavities such as cavities with a diameter of 1.1 nm (l lA) or larger, preferably lnm (lOA) or larger, preferably essentially free from cavities having a diameter of 0.9nm (9A) or larger. Preferably the zeolite catalyst should be essentially free from any cavities having a volume larger than 6nm³ (6000A³). By using a zeolite catalyst having pores with a diameter of 0.7nm (7 A) or smaller but 0.4nm (4A) or larger the catalyst allows the solvolysis products to enter but recondensation and repolymerization is reduced or avoided. Without being bound by theory but the maximum diameter of 0.7nm is believed to minimize the risk of fitting more than one monomer or compound in each pore of the zeolite and thereby limiting the amount of recondenzation or repolymerization. Zeolites having larger pores or cavities fit two or more monomers which may then react and form dimers or trimers.

According to the present disclosure the zeolite-based solid catalyst has preferably at least one of the following features: - pores with a diameter of 0.7nm (7A) or smaller, preferably 0.65nm or smaller, more preferably 0.6nm or smaller but preferably 0.3nm (3 A) or larger, more preferably 0.4nm or larger, more preferably 0.45nm or larger, more preferably 0.5nm or larger,

- a Si/Al ratio of 7 to 50, preferably 10-35, more preferably 12- 15,

- possesses a bidirectional or a bidirectional system of pores, preferably a bidirectional system of pores,

- possesses a topology of pores with at least 10 membered-ring and preferably 12 membered-ring,

-has a unit cell volume of 5nm³ (5000A³) or less, preferably 4.5 nm³ or less, preferably 1 nm³ or larger, more preferably 3 nm³ or larger. In one embodiment the unit cell volume is 4-4.3 nm³ (4000-4300A³),

- tridirectional structure consisting of straight 12-membered ring channels of a free aperture of 0.66*0.67nm (6.6*6.7 A) along axis [100] and zigzag 12-membered rings channels of 0.56*0.56nm (5.6*5.6 A) along axis [001], preferably without cavities,

- a micropore volume of less than 0.25pm³/g, preferably less than 0.20pm³/g,

- an acidity (Bronsted) of 200-270 pmol/g, preferably 220-260 pmol/g, more preferably 240-250 pmol/g when measured at 250°C,

-that the maximum diameter of a sphere that can be included is 0.8nm (8 A) or smaller, preferably 0.75nm or smaller, more preferably 0.7nm or smaller, but preferably 0.4nm or larger. In one embodiment the maximum diameter of a sphere that can be included is 0.6-0.7nm (6-7A),

-the zeolite catalyst has a nanocrystalline structure with unit cells that preferably are tetragonal,

- is essentially free from cavities or supercages. In one embodiment the zeolite catalyst is essentially free from cavities having a diameter of l. lnm (l lA) or larger, preferably lnm (lOA) or larger, preferably essentially free from cavities having a diameter of 0.9nm or larger,

- the maximum diameter of a sphere that can diffuse along is 0.7nm (7A) or smaller, preferably 0.65nm or smaller, more preferably 0.6nm or smaller, preferably 0.4nm or larger, more preferably 0.45nm or larger, -a SBET (surface area) of less than 600m² / g.

These zeolite catalysts have small enough pores to reduce the recondensation or repolymerization and also high enough acidity. A high yield and good control is obtained using these types of catalysts.

In one embodiment the unit cell of the zeolite-based solid catalyst has a volume of 6 nm³ (6000A³) or less, preferably 5 nm³ or less, preferably 4.5 nm³ or less, preferably 1 nm³ or larger, more preferably 3 nm³ or larger. In another embodiment the maximum diameter of a sphere that can be included is less than 0.8nm (8Ά), preferably less than 0.7nm, but preferably 0.4nm or larger, or more preferably 0.5nm or larger. In yet another embodiment the maximum diameter of a sphere that can diffuse along is 0.7nm or smaller, preferably 0.65nm or smaller, more preferably 0.6nm or smaller, preferably 0.4nm or larger, more preferably 0.45nm or larger.

In another embodiment the zeolite-based solid catalyst is essentially free from cavities or supercages. In one embodiment the zeolite catalyst is essentially free from cavities having a diameter of l. lnm (l lA) or larger, preferably lnm (lOA) or larger, preferably essentially free from cavities having a diameter of 0.9nm or larger.

The zeolite based solid catalyst of the present disclosure has preferably a tridirectional system of pores, an acidity (Bronsted) of 200-270 pmol/g, preferably 220-260 pmol/g, more preferably 240-250 pmol/g when measured at 250°C and a Si/Al ratio of 7 to 50, preferably 10-35, more preferably 12-15 and/or a tetragonal crystal structure and/or tridirectional structure consists of straight 12-membered ring channels of a free aperture of 6.6*6.7 A along axis [100] and zigzag 12-membered rings channels of 5.6*5.6 A along axis [001], preferably without cavities and/or a micropore volume of less than 0.25pm³/g, preferably less than 0.20pm³/g. In one embodiment the zeolite-based solid catalyst is beta zeolite or a zeolite having a BEA framework. In another embodiment the beta zeolite is a beta 1 zeolite.

Suitable solvents are polar solvents or mixtures comprising a polar solvent and water or the solvent is a mixture of at least two polar protic solvents or is a mixture of at least one polar protic solvent and at least one aprotic solvent. The polar solvent or the polar protic solvent is preferably selected from but not limited to alcohols preferably methanol, ethanol, 1 -propanol, 2 -propanol, 1 -butanol and 2 -butanol. In another embodiment the solvent is or comprises a cyclic ether preferably 1,4-dioxane. In yet another embodiment the solvent is or comprises acetonitrile. In one embodiment the solvent is a mixture of at least two polar protic solvents or is a mixture of at least one polar protic solvent and at least one aprotic solvent wherein at least one of the solvents is selected from methanol, ethanol, 1 -propanol, 2 -propanol, 1 -butanol, 2- butanol 1,4-dioxane and acetonitrile. In another embodiment the solvent is a mixture of at least two polar protic solvents wherein one polar protic solvent is water and wherein at least one solvent is preferably an alcohol preferably selected from methanol or ethanol more preferably ethanol. In yet another embodiment the solvent is a mixture of at least one polar protic solvent and at least one aprotic solvent wherein the polar protic solvent is water and wherein the at least one aprotic solvent is a cyclic ether preferably dioxane.

When the solvent is a mixture of a solvent and water the water content is in the range of from 0.5 to 20 % of the total volume of solvent mixture, preferably from 5 to 15%. The volume ratio between water and the polar solvent preferably alcohol or the aprotic solvent is between 15: 1 to 1:4, preferably between 12: 1 to 5: 1, more preferably between 10: 1 to 8: 1 or around 9: 1. When the solvent is a mixture of at least one polar protic solvent and at least one aprotic solvent the polar protic solvent is preferably water and the at least one aprotic solvent is a cyclic ether preferably dioxane or 1 ,4-dioxane. In a preferred embodiment the solvent is a mixture comprising ethanol and water in a volume ratio of 15: 1 to 1 :4, preferably 12: 1 to 5: 1, more preferably 10: 1 to 8: 1 or around 9: 1 (ethanol: water). An advantage of said suitable solvents is that they result in high yield of wanted compounds. A benefit of using water or a solvent mixture comprising water is that water promotes the cleavage of C-0 bond and results in an increase in the formation of furfural. However, a high water content limits the formation of aromatic monomers or compounds. When producing furfural a higher water content in the solvent mixture is beneficial. In one embodiment the water content in the solvent mixture is at least 5 volume%, preferably at least 7 volume%, more preferably at least 10 volume%, more preferably at least 12 volume%. In one embodiment the water content is 18-22 volume%, preferably around 20 volume%.

During the heating the biomass undergoes solvolysis forming solvolysis products. The solvolysis products are then brought into contact with the catalyst optionally forming a second mixture. This may be done simultaneously as the solvolysis or may be done in one or more separate steps. The whole method of the present disclosure is preferably conducted as a one pot synthesis where the mixing and heating is done in one pot. Heating of the second mixture is preferably done in the same manner and/or at the same temperature as heating of the first mixture and is preferably done at a temperature of 120-300°C, preferably at 120-25OC, more preferably at 150-25OC, more preferably at 180-240°C, more preferably at 200-240C, more preferably at 200- 230° C. When producing monomers from lignin such as monophenolic monomers the second mixture is preferably heated at 200-240°C preferably around 220°C. When producing furfural the second mixture is preferably heated at 180-220°C preferably at 190-210°C, more preferably around 200°C. The heating may be done for a suitable period of time preferably from 0.1 to lOh, preferably from 0.5 to 5h and more preferably for 2h. Still the time is dependent on the volume of the mixture. A pressure may also be applied during the heating. In one embodiment the pressure during the heating of the second mixture is from 1 to 80 bar, preferably from 5 to 20 bar. Applied pressure may shorten the treatment time and may increase the yield. In one

embodiment the heating of the second mixture is conducted in a sealed container. In another embodiment the method is conducted at atmospheric pressure. The pH of the second mixture is preferably acidic. In one embodiment the pH is 2-6, preferably 3-5.

The obtained monomers are preferably monophenolic monomers and preferably selected from compound 14 to 29 of Figure 7. The yield of said compounds may be 10- 20%. In a preferred embodiment the major constituents of the monophenolic compounds are:

The obtained compounds from cellulose and / or hemicellulose may be furfural, esters of levulinic acid, ethylfurfuryl alcohol, ether and ethers of sugars such as ethyl glucosides and / or 5-hydroxymethylfurfural. The yield of furfural may be at least 8%, preferably at least 10%.

A composition comprising monomers and / or furfural, solvent and catalyst is obtained after the heating. The wanted products, monomers and/or furfural, may be separated or isolated using any suitable technique such as filtration, distillation, solvent extraction etc. or combinations thereof. The monomers are preferably monophenolic monomers. In one preferred embodiment the present method results in a composition comprising monophenolic compounds where the major constituents are:

After the heating step the catalyst may be separated or isolated using any suitable technique preferably through filtration or sedimentation and decantation. The zeolite catalyst may be regenerated and reused which is very beneficial.

The obtained composition comprises a mixture of monophenolic compounds and furfural where the mixture of monophenolic compounds preferably comprises compounds selected from compound 14 to 29 of Figure 7, and furfural. The obtain composition may further contain esters of levulinic acid, ethylfurfuryl alcohol, ether and ethers of sugars such as ethyl glucosides and/or 5-hydroxymethylfurfural. The obtained composition comprises a mixture of monophenolic compounds and furfural where the mixture of monophenolic compounds preferably comprises the following monophenolic compounds as its major constituents:

The composition may preferably further comprise esters of levulinic acid, and ethers of sugars, and/or 5-hydroxymethylfurfural.

A carrier liquid may also be added to the composition in order to make the composition or the monophenolic compounds more suitable for further treatments in a refinery process such as a conventional refinery process. The carrier liquid may be any suitable oil for example a hydrocarbon oil, crude oil, bunker oil, mineral oil, tall oil, creosote oil, tar oil, fatty acid or esterified fatty acid. In one embodiment the carrier liquid is a fatty acid or a mixture of fatty acids. The fatty acid may be a tall oil fatty acid (TOFA) or refined or distilled TOFA. In another embodiment the carrier liquid is esterified fatty acids such as FAME (fatty acid methyl ester) or triglyceride. In one embodiment the carrier liquid is a crude oil. In one embodiment the carrier liquid is bunker fuel or bunker crude. In another embodiment the carrier liquid is a hydrocarbon oil preferably a gas oil or a mineral oil. In one embodiment the carrier liquid is a mixture of esterified fatty acid and a mineral oil, hydrocarbon oil, bunker fuels or crude oil. In another embodiment the carrier liquid is a mixture of a hydrocarbon oil or a mineral oil and a fatty acid. In one embodiment the carrier liquid is creosote oil or tar oil. Since the composition may be used for preparing fuels the carrier liquid does not have to be an already hydrotreated or cracked liquid such as diesel, instead the carrier liquid should be a liquid that may be hydrotreated or cracked in a refinery process in order to form fuel. By using a non-hydrotreated or non-cracked carrier liquid conventional refinery processes may be used and carrier liquids that any way would be refined can be used.

The composition may comprise 10-99 weight% of carrier liquid of the total weight of the composition, such as 20 weight% or more, or 40 weight% or more, or 60 weight% or more, or 80 weight% or more, or 99 weight% or less, or 85 weight% or less, or 65 weight% or less. In one embodiment the amount of carrier liquid is 60-90 weight% such as 65-85 weight%.

The composition may comprise 1-90 weigh t% of monomers and/or furfural. In one embodiment the composition comprises 10 weight% or more, preferably 20 weight% or more, or more preferably 40 weight% or more, but preferably 70 weight% or less, or preferably 60 weight% or less, or more preferably 50 weight% or less.

By using C14 method the origin of the monophenolic monomer and furfural can be determined.

A fuel can be obtained from the present composition through hydroprocessing such as hydrotreatment or hydrocracking the composition.

During hydrotreating the feed may be exposed to hydrogen gas (for example 20- 200bar) and a hydrotreating catalyst (NiMo (Nickel Molybdenum), CoMo (Cobalt Molybdenum) or other HDS, HDN, HDO catalyst) at elevated temperatures (200- 500° C). The hydrotreatment process results in hydrodesulfurization (HDS),

hydrodenitrogenation (HDN), and hydrodeoxygenation (HDO) where the sulphurs, nitrogens and oxygens primarily are removed as hydrogensulfide, ammonia, and water. Hydrotreatment also results in the saturation of olefins and possibly also aromatic compounds. Catalytic cracking is a category of the broader refinery process of cracking. During cracking, large molecules are split into smaller molecules under the influence of heat, catalyst, and/or solvent. There are several sub-categories of cracking which includes thermal cracking, steam cracking, fluid catalyst cracking and hydrocracking. During thermal cracking the feed is exposed to high temperatures and mainly results in homolytic bond cleavage to produce smaller unsaturated molecules. Steam cracking is a version of thermal cracking where the feed is diluted with steam before being exposed to the high temperature at which cracking occurs. In a fluidized catalytic cracker (FCC) or“cat cracker” the preheated feed is mixed with a hot catalyst and is allowed to react at elevated temperature. The main purpose of the FCC unit is to produce gasoline range hydrocarbons from different types of heavy feeds. During hydrocracking the hydrocarbons are cracked in the presence of hydrogen.

Hydrocracking also facilitates the saturation of aromatics and olefins.

EXAMPLES

The procedure for the preparation of model compound 1 and 1-OMe

4-(3-hydroxyprop- 1 -en- 1 -ylfpheno l and 3-(3,4-dimethoxyphenyl)prop-2-en- l-ol

Product 1 was synthesized according to the following 2 steps procedure: 3-(3,4- dihydroxyphenyljacrylic _acid (28mmol) was dissolved in MeOH (100 ml), 10 drops of H SO4 cone were added and mixture was refluxed 24 hours. MeOH was removed under reduced pressure; acid was neutralized by NaHC03 solution and product was extracted with dichloromethane, organic layers were washed with brine, dried over anhydrous Na S04_, filtrated, and concentrated in vacuo. Product was used for the next step without purification.

To a solution of AICI3 in dry THF under Ar atmosphere LiAlH4 solution in THF (14 ml, 14 mmol) was added at 0°C. After completion the addition solution was stirred at room temperature 30 mins. Solution of the ester in dry THF was added dropwise to the reaction mixture and resulting solution was stirred during 2 hours; after that LiAlH was quenched with EtOAc and concentrated water solution of potassium sodium tartrate was added and mixture was stirring for 2 hours. Then organic layer was separated, washed with brine, dried over anhydrous Na2S04, filtered and concentrated in vacuo. Product was purified by column chromatography (petroleum ether: ethyl acetate = 1: 1) to give solid (80%). Spectral data were in accordance with those previously reported.

Experimental Section Analytical techniques

^!H-NMR spectra were recorded with a Bruker 400 (400 MHz) spectrometer as solutions in CDC13. Chemical shifts are expressed in parts per million (ppm, 6) and are referenced to CHC13 (6 = 7.26 ppm) as an internal standard. All coupling constants are absolute values and are expressed in Hz. ¹³C -NMR spectra were recorded with a Bruker 400 (101 MHz) spectrometer as solutions in CDC13 with complete proton decoupling.

GC measurements were performed on a Shimadzu GC-2010 Plus equipped with a HP-5 MS capillary column (30m * 0.25 mm * 0.25 pm) and an FID detector. Dodecane was used an internal standard. GC-MS measurements were performed on a Shimadzu GC- MS-QP2020.

Textural properties including BET surface area and micropore volume of the samples were measured by N2 adsorption/ desorption in a Micromeritics ASAP2000 at 77 K.

The chemical analyses were carried out in a Varian 715-ES ICP-Optical Emission spectrometer. The samples were dissolved in HNO₃/HCI/HF aqueous solution before measurement.

The acidity of the catalysts was measured by IR spectroscopy (Nicolet 710 FTIR spectrophotometer) combined with adsorption-desorption of pyridine at 10 ⁴ Torr at 250 °C and 350 °C using self- supported wafers of 10 mg cm ² that were degassed overnight under vacuum (10 ⁴ to 10 ⁵ Pa) at 400 °C. After each desorption step, the spectrum was recorded at room temperature and the background subtracted. All the spectra were scaled according to the sample weight. The acidity of the catalysts was measured as pmol pyridine per gram of catalyst at different temperatures, calculated by using the extinction coefficients, from the area of the IR band of Bronsted and Lewis acid sites at ca. 1545 and 1450 cm ¹, respectively.

Materials

All chemicals were purchased from Sigma Aldrich. Beta-1 (CP81 1) and HY- 1, HY-2 and HY-3 (CBV 720, 740 and 760), were purchased from PQ Zeolites B. V. and, before use, the catalysts were calcined at 550 °C for 5 h.

Table 1. Characterization of catalysts.

Catalyst Medium Si/Al SBET, Micro. Vol. Acidity mpioΐ/g

of ratio m²/g (cm³/g) Bronsted Lewis synthesis 250°C 350°C 250°C 350°C

Beta- 1 OH¹ 1275 580 OΪ8 247 225 285 125

HY- 1 OH- 15 723 0.31 309 171 42 43

HY-2 OH- 20 666 0.29 1 12 47 22 25

HY-3 OH- 30 753 0.32 96 33 38 35

S_BET=BET surface area General procedure for catalytic reactions

1. General procedure for reactions of model compounds with zeolites in vial

A 2-5 mL microwave vial (Biotage) equipped with a stir bar was loaded with the corresponding model compound and catalyst. Solvent (standard solution of dodecane in Ethanol/ water) was added and the vial was sealed. The reaction mixture was stirring for specified time at specified temperature. After the completing of the reaction the reaction mixture was filtrated and analyzed by GC-FID and GC-MS.

2. General procedure for reactions of wood and model compounds in stainless steel reactor

A stainless steel reactor, purchased from Swagelok, equipped with a stir bar was loaded with the wood sawdust or model compound 1 and corresponding catalyst. Solvent was added and the reactor was sealed. The reaction mixture was stirring for specified time at specified temperature. After the completing of the reaction, reaction mixture was filtrated; internal standard (dodecane) was added to the solution and aliquot was taken and analyzed by GC-FID and GC-MS. Solvent and furfural were evaporated from the reaction mixture (in case of wood) and the oil residue was extracted with EtOAc/LEO. Organic layer was analyzed by GC-FID and GC-MS.

3. General procedure for reactions of carbohydrates with zeolites

A 2-5 mL microwave vial (Biotage) equipped with a stir bar or stainless steel reactor (for the reactions with cellulose) was loaded with the corresponding carbohydrate compound and beta- 1 catalyst. Solvent (standard solution of dodecane in ethanol and water) was added and the vial was sealed. The reaction mixture was stirring for a specified time at a specified temperature. After the completing of the reaction the reaction mixture was filtrated and analyzed by GC-FID and GC-MS.

4. General procedure for ether cleavage of model dimer (5).

A microwave vial reactor equipped with a stir bar was loaded with 60 mg of the l-(3,4- dimethoxyphenyl)-2-(2-methoxyphenoxy) propane- 1 ,3-diol substrate (5) . 2 mL of ethanol and water were added and 40 mg of water and the reactor was sealed. The reaction mixture was stirring for 2 hours at 200 °C under microwave. After the completing of the reaction, reaction mixture was filtrated; internal standard (dodecane) was added to the solution and aliquot was taken and analyzed by GC-FID and GC-MS.

Identification and quantification of products from the reaction with wood In order to calculate yields and conversions in the reactions with model compounds and wood calibration curves were built with dodecane as internal standard.

Main monomers were identified by GC-MS. Compounds 14-29 were identified by fragmentation pattern in mass spectrum. Obtained spectra were compared with those obtained from Wiley Subscription Services, Inc. (US). Yields of monomers from lignin and furfural were calculated as follows: mass of monomer * 100%

yield, % =— - - - biomass * lignin content

mass of furfural * 100%

yield, % =

biomass * (hemicellulose + cellulose) content

Results and discussion A) Study on lignin model compounds:

During organosolv pulping of lignocellulose, depolymerization of lignin takes place releasing lignin fragments and allylic alcohols. Coniferyl and sinapyl alcohols are the two main monomers obtained from the solvolytic cleavage of lignin of hard wood. Together with the reactivity of the allyl alcohols, coniferyl has an additional site of reactivity, for recondensation in the position 5 in the aromatic ring, and so it is more prone to form new C-C bonds. To investigate the possible conversion and stabilization of released allylic alcohols during lignocellulose organosolv pulping in the presence of zeolites with Bronsted acid sites, the reactivity of the most reactive one, i.e. coniferyl alcohol was studied. Then, two commercial zeolite samples with Si/Al ratio around 12- 13 were chosen, beta and HY zeolites, both offering large pores structures that allow the diffusion of large molecules but with an important structural difference, namely presence of large cavities in case of faujasite (HY) zeolite and absence of those for beta zeolite. In addition to favor diffusion, the presence of cavities can promote bimolecular reactions and stabilization of voluminous transition state beta zeolite is a tridirectional structure with large pores, consisted by intergrowth of two pore systems without cavities. One of them consists of straight 12-membered ring channels of a free aperture of 6.6*6.7 A along axis [100] and the other of zigzag 12-membered rings channels of 5.6*5.6 A along axis [001]. Ultrastable HY zeolite has a tridirectionnal and large pore structure consisted of sodalite cages (supercage) which are connected through hexagonal prisms. The pore is formed by a 12-membered ring with a free aperture of 7.4

A.

When coniferyl alcohol 1 was subjected to organosolv pulping conditions, at 200°C, in EίOH/¾0 solvent mixture and in the presence of beta- 1 zeolite, indene 2 and reduced products 3 (cis- and trans-isoeugenol and eugenol) were the main products obtained with a 78 % total monomers yield (Figure 2, Table 2 -Entry 1 , Figure 11). Indene 2 results from intramolecular alkylation of aromatic ring and products 3 result from hydrogenolysis reaction. When the coniferyl alcohol was treated under same reaction conditions without zeolite, the main product was coniferyl alcohol ethyl ether (4) , obtained with 40 % yield (Figure 11 , Entry 10). However, when the reaction was performed in the presence of homogeneous mineral acid (HC1), only traces of monomers were detected and reaction vessel was corroded (Figure 1 1, Entry 9). These results showed that zeolite was able to stabilize the allyl alcohol 1 through hydrogenolysis and alkylation processes. Since for hydrogenolysis process a reducing agent is required and that alcohol can acts as reducing agent the effect of several solvents and additives on yield and composition products was tested. The results are reported in Table 2 (entries 1-3). Interestingly, 2/3 products molar ratio of 2.6 was much higher when MeOH (poor hydride donor) was used under organosolv pulping conditions. The reaction with EtOH resulted in the ratio of 0.3. When using i-PrOH (strong hydride donor), it resulted in formation of product 3 in 70 %, while no product 2 was detected. Because during the pulping process of lignocellulose, sugars and formic acid are released and are well known to act as reducting agent, the reactivity of allyl alcohol 1 was also studied in the presence of xylose and formic acid. However, yields of products 2 and 3 were similar to the values obtained before (Table 2, entries 4-5). Since lower yield of reduced products was observed in case of MeOH, and comparable results for both EtOH and i-PrOH were obtained, it can be concluded that ethanol acts as a reducing agent and it can be considered as an efficient hydride donor under applied reaction conditions. Moreover, these results showed that beta zeolite presents adequate catalytic properties to stabilize coniferyl alcohol into indene and propenyl phenol derivatives.

When coniferyl alcohol 1 was submitted to organosolv pulping conditions in the presence of HY zeolite the total yield of monomers was much lower. This result is attributed to the recondensation reactions that can take place with less steric limitations within the large cavities of HY zeolite (Table 1, Entries 6-8).

Table 2. Catalytic conversion of coniferyl alcohol 1 over zeolites.

Entry Catalyst Solvent/ additive, mL(mg) Yield Yield Total yield of

2, % 3,% monomers, %

1 beta- 1 EtOH/H₂0 (4.5/0.3) 16 57 78

2 beta- 1 MeOH/H₂0 (4.5/0.3) 18 7 29

3 beta- 1 iPrOH/H₂0 (4.5/0.3) 0 70 80

4 beta- 1 EtOH / H₂0 / HCOOH

(4.5/0.3/0.1) 15 42 61

5 beta- 1 EtOH / H₂0 /xylose

(4.5/0.3/ 10) 13 46 62

6

HY-2 EtOH/H₂0 (4.5/0.3) 0 23 28

7 HY-3 EtOH/H₂0 (4.5/0.3) 0 20 22

8 HY- 1 EtOH/H₂0 (4.5/0.3) 0 16 25

Reaction conditions: 20 mg catalyst, 6 mg model compound 1, t=0.5 hour, T= 200 °C. beta- 1 (Al_beta zeolite, Si/Al= 12.5), HY- 1 (Y zeolite, Si/Al= 15), HY-2 (Y zeolite, Si/Al=20), HY-3 (Y zeolite, Si/Al=30)

Lignin is a polymeric molecule consisting of assembling of three monolignols through etheric C-0 linkages (mostly a-O-4, b-O-4’, 4-0-5) and C-C linkages (e.g., 5-5', b- 1 , b- 5, b-b'). The etheric b-O-4’ linkage is the dominant one and corresponds up to 60% of total linkages in hardwood. Since C-0 ether bonds are significantly weaker than C-C bonds, the b-O-4’ linkage is a model linkage largely studied during the investigation of lignin depolymerization. Because during the organosolv pulping fragments of lignin can be released in form of oligomers and dimers, herein we studied the reactivity of the protonic beta zeolite towards the cleavage of b-O-4’ bond. The l-(3,4-dimethoxyphenyl)- 2-(2-methoxyphenoxy)propane- l,3-diol substrate (5) was used as dimer model (Figure 4) to study the ether cleavage under organosolv pulping conditions in ethanol and other solvents. Dimer 5 with methoxy substituents on both aromatic rings was chosen as a model substrate. 2-methoxyphenol (8), dimethoxyphenylacetaldehyde (9), dimethoxyphenylacetaldehyde diethyl acetal (11) (3,4-dimethoxyphenyl)acrylaldehyde (10) are the products resulting from the b-O-4’ cleavage of model compound 5, showing that beta zeolite is enable to carry out the acidolysis of ether linkage (Table 3). However, products of b-O-4’ cleavage were obtained in quite low yields, and substantial amount of dimers (5, 6 and 7) were detected in the reaction mixture. We assume that steric factors and control by diffusion inside the pores contribute to the lower rate of conversion of dimer 5 in comparison to allylic alcohol 1. Thus, the main pathway for the formation of monomers must be via homolysis of b-O-4’ and stabilization of released monomers in the pores of zeolite.

In addition, taking into account that C2 -aldehydes are very reactive towards self condensations, the stability of phenylacetaldehyde under organosolv pulping conditions was closely checked. Phenylacetaldehyde that is readily available, very reactive and without steric impediment was chosen as a model substrate. Reaction was conducted with concentrations of phenylacetaldehyde much higher than those during the organosolv pulping in order to compare the rates of self-condensation of aldehyde with Beta and HY zeolites. When the yield of C2 -aldehyde was plotted versus reaction time (Figure 5, Table 4) in the presence of beta- 1 and HY- 1 zeolites, a constant decrease of the yield with reaction time was observed. It is clear that in case of HY-zeolite recondensation reactions proceed with much higher rate. These results showed that zeolite topology and pore size can controlled and minimize the recondensation reactions which take place inside the pores beta- 1 zeolite large pore structure does not present cavities in comparison with faujasite (FAU) structure (HY) and gives lower oligomerization of phenylacetaldehyde.

Table 3. Catalytic results obtained for study of b-O-4 cleavage of model 5 in the presence of beta- 1 zeolite. Conversion given in %.

Sum% Balance%

Solvent Conv. 8 9 10 11 6 7

Ph-OH Aid. Ph-OH Aid.

Dioxane 100.0 44.8 7.8 10.3 0.1 25.2 0.0 44.8 18.2 65.1 38.5

ACN 61.3 27.0 1.5 9.7 0.0 27.5 0.0 27.0 11.2 87.7 72.0

Ethanol 90.5 21.5 7.2 4.1 2.0 3.4 34.9 21.5 13.4 69.3 61.2

Ethanol* 91.8 26.0 8.5 1.8 2.4 1.6 30.5 26.0 12.6 66.3 52.9

IPA* 88.7 28.7 11.3 3.0 0.2 3.6 21.3 28.7 14.5 64.9 50.8

Reaction conditions: 16.5 mg beta- 1 (Si/Al= 12.5), 60 mg model compound 5, 2 mL of solvent, 40 mg of water, 2 hours of reaction time, 200 °C and dodecane was used as standard. *180°C for 3 hours of reaction time.

Table 4. Stability of penylacetaldehyd 12. Total yield of

Catalyst Time, mins Solvent, m Yield 12, % Yield 13,%

monomers, % beta- 1 15 Et0H/H20 (3/0.3) 48 27 75 beta- 1 30 Et0H/H20 (3/0.3) 36 27 63 beta- 1 60 Et0H/H20 (3/0.3)) 38 16 54

HY-1 15 Et0H/H20 (3/0.3) 21 23 44

HY-1 30 Et0H/H20 (3/0.3) 18 16 34

HY-1 60 Et0H/H20 (3/0.3) 10 8 18

Reaction conditions: 20 mg catalyst, 33,6 mg model compound 12, T= 200 °C. beta- 1

(Al_beta zeolite, Si/Al=12.5), HY- 1 (Y zeolite, Si/Al=15).

With this study of reactivity of monomeric and dimeric model compounds we demonstrate that beta zeolite is a good candidate to stabilize allylic alcohols released from organosolv pulping in the presence of a reducing agent such as ethanol. As well as beta zeolite is able to promote b-O-4’ cleavage of possible dimers released from pulping through acidolysis without the need of use of capping agent or metal.

B) Study with Birch wood: As it has been mentioned above, during the organosolv pulping, b-O-4’ bonds in lignin are reductively cleaved to large extent. Released monomers mostly comprise allylic alcohols. Reactions with model compounds demonstrated that inside the pores of zeolites those molecules can be transformed into stable monomers. Reactions with carbohydrates model compounds and cellulose, xylose, glucose (Table 5) and literature reports demonstrate that products of dehydration of sugars (furfural, lactic acid, 5- hydroxymthelfurfural) are forming in presence of zeolites. Thus, we envisioned that different platform-molecules might be obtained in one single process from all three components of biomass if organosolv pulping of lignocellulose was performed in the presence of protonic beta zeolite. In order to investigate the feasibility of the method we selected birch wood as biomass source. Birch wood was treated under depolymerisation conditions, in the presence of beta 1 zeolite, in mixture ethanol/ water (v/v 9: 1) at temperature comprised between 180 and 220°C. After reaction, the crude mixture was filtered and concentrated under vacuum. Then, the bio-oil was extracted with EtOAc/EBO in order to separate the monophenolic compounds from the products derived from the carbohydrates. Various syringyl and coniferyl derivatives proceeding from lignin were obtained and described in Figure 7. The examination of the structure of the main products (14-29) supports the raised hypothesis in which the major pathway for the lignin depolymerisation occurs via lignin solvolysis and the release of allylic alcohols, which are converted at a later stage inside the pores of the zeolite into stable products through different reactions of disproportionation, isomerization, alkylation and reduction.

Table 5. Catalytic conversion of carbohydrates.

Substrate Cat / sub Temp., °C Time, h Yield furfural/ Ethyllev, %

Xylose^a 0.3 180 0.5 77

Glucose^a 0.3 180 1 48

Cellulose^b 1.4 200 2 18

Cellulose^b 0.75 200 2 26

Cellulose^b 0.3 200 2 36

Cellulose^b 0.1 200 2 21

Cellulose 0.7 200 2 18/ 12

a 2 mL dioxane, 0.1 mL water, MW vial. ^b 4.5 mL dioxane, 0.5 mL water, stainless steal reactor. °4.5 mL EtOH, 0.5 mL water, stainless steel reactor. Ethyllev. =

ethyllevullinate

According to the literature reports and control experiments (Table 5), both hemicellulose and cellulose can be converted to the furfural in presence of beta zeolites. Likewise, furfural was the main product detected deriving from the cellulose and hemicellulose fraction in the birch wood. Identified products also included ethyl-levulinate and ethylfurfuryl alcohol ether, as well as small amounts of ethyl glucosides (Figure 8). Maximum yield of furfural was obtained when reaction was performed with addition of 20 v% of water and constituted 23 mol% (14.3 wt%) accounting for the cellulose and hemicellulose content of wood. However, high water content was not optimal for the formation of aromatic monomers from the lignin fraction of the birch wood. Yield of quantified aromatic monomers from lignin was calculated to be 16.9 wt% (17.5 Cmol%) accounting for the lignin content, when reaction was performed at 220 °C, which demonstrates that the methodology developed is applicable to biomass and has advantages to previous reports for acid-catalyzed pulping, where yields of monomers ranged from 2 to 10 wt%. In our case, i.e. in the presence of Beta zeolite, it was possible to increase the yield of monomers even further to 20 wt% (Table 6) when decreasing the ratio of wood to solvent. Reaction in the absence of the Beta zeolite catalyst at 220 °C resulted in formation of allylic ethers in significantly lower yield (1.2 wt%, Figure 12).

Table 6. Yields of lignin monomers and furfural for organosolv pulping of birch in the presence of beta- 1 zeolite. Entry Catalyst T°C Yield (14-29) , wt% Furfural, wt%

1 beta- 1 180 4.4 2.4

2 beta- 1 200 7.9 12.7

3^a beta- 1 200 13.1 10.5

4 beta- 1 220 16.9 9.4

5^b beta- 1 200 4.5 6.1

6^C beta- 1 200 6.3 14.3

7^d beta- 1 220 20 n.d.

Reaction conditions: 50 mg catalyst, 200 mg wood, 4.5mL EtOH, 0.5 mL ¾0. Yield calculated as: mass of products/mass of lignin, and mass of furfural/ mass of (cellulose + hemicellulose). ^a 100 mg wood, 25 mg catalyst. ^b 4.75mL EtOH, 0.25 mL ¾0 ^c 4mL EtOH, 1 mL ¾0. ^d 100 mg wood, 25 mg catalyst.

Based on the results with model compounds and birch wood we proposed the following pathway for the overall process (Figure 9). Fractionation of wood begins with a solvolytic cleavage of ether and ester bonds within the lignin-carbohydrate complex (LCC). Oligomeric and polymeric fragments of lignin, released into the solution, undergo the reductive cleavage, facilitated by reducing sugars or solvent, resulting in the formation of allylic alcohols. The latter ones diffuse inside the pores of zeolites and get transformed mainly into stabilized products coniferyl and syringyl derivatives, (see experimental results summarized in the Table 6). Ethanol was shown to be a reducing agent and a good hydride donor under the developed reaction conditions, since process in methanol resulted in lower yield of desired products (Table 2). From the results given in the Table 6 it can be noticed that addition of water is required, presumably to promote the cleavage of LCC, however, excess of water might lead to the deactivation of the catalyst or side-reactions of monomers. An optimal ratio ethanol/ water 9/ 1 was implemented.

Hemicellulose and cellulose are fractionated under conditions of organosolv pulping, in the presence of beta- 1 into C-5 and C-6 sugars which are mainly transformed into furfural and some other products. These results agree with reported experiments with cellulose, glucose and xylose in which furfural is produced as a main product from all of them. While it is well known that C-5 sugars and C-6 sugars, such as glucose form predominantly 5-HMF under acidic conditions, it has been recently reported that beta- zeolites are able to convert glucose into furfural via retro-aldol reaction with a good selectivity. In this case, the solvent plays a crucial role on the selectivity of this process. In agreement with literature reports we have found that in our case, the best yield of furfural was achieved in dioxane, while other products (LA, 5-HMF, etc.) are formed in larger quantities when using ethanol as solvent. Conclusion

This method is a new approach for prevention of recondensation reactions during pulping of biomass. This is achieved by tuning pore size of the zeolite in order to hamper the bimolecular condensations and favor monomolecular reactions. It has been demonstrate an additive and transition metal-free methodology that can be successfully applied to woody biomass. Studies with model compounds revealed the reaction pathway which is a transfer-hydrogenolysis of allylic alcohols inside the pores of zeolites. Yields of 20 wt% of monomers are superior to the previously reported for acid-catalyzed pulping of wood in absence of metals (2-10 wt%). In the present method, simultaneously, hemicellulose and cellulose are depolymerized and the released carbohydrates are transformed into platform chemicals over acid active sites of the beta zeolite being furfural the main product obtained. This finding enables novel catalytic fractionation methodologies that are based on inexpensive acid catalysis without the need to use stoichiometric capping agents nor transition metal catalyzed reductions.

Claims

1. A method of producing monomers from lignocellulosic biomass by acid-catalyzed fractionation of lignocellulosic biomass, comprising the steps of:

a. mixing the lignocellulosic biomass, a zeolite-based solid catalyst, and a solvent; and

b. heating the mixture obtained in step a at a temperature of 120°C-250°C or higher.

wherein the zeolite based solid catalyst possesses a pore system without cavities and/or wherein the zeolite-based solid catalyst is beta zeolite-.

2. The method according to claim 1 wherein the zeolite-based catalyst possesses a topology of pores with at least 10 membered-ring and preferably 12 membered- ring.

3. The method according to claim 1 wherein the zeolite-based solid catalyst

possesses a nanocrystalline structure.

4. The method according to claim 1 wherein the weight percent of the zeolite- based solid catalyst with respect of the weight of the lignocellulosic biomass is 1-50 wt% and preferably 5-25 wt%.

5. The method according to claim 1 wherein the zeolite-based solid catalyst is

separated from the mixture after completion of the heating step b.

6. The method according to claim 1 wherein the method of the invention is

performed in a stirred batch or a continuous stirred-tank reactor.

7. The method according to claim 1 wherein the monomers produced is furfural and wherein the content of furfural is 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, by weight of the composition.

8. The method according to claim 1 wherein the mixture in step b is heated at a temperature of 150-250°C, and most preferably at 200-240°C.

9. The method according to claim 1 wherein the mixture in step b is heated for 0.1 to 10 h, more preferably for 0.5 to 5h and most preferably for 2 h under a pressure from 1 to 80 bars.

10. The method according to claim 1 wherein the zeolite-based solid catalyst presents a framework Si/Al ratio in the range of 7-50, preferably in the range of 10-35.

11. The method according to claim 1 wherein the zeolite-based solid catalyst possesses a tridirectional system of pores.

12. The method according to claim 1 wherein the lignocellulosic biomass is hardwood or softwood or a mixture thereof.

13. The method according to claim 1 wherein the solvent is a polar solvent, such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol 1,4-dioxane or acetonitrile and preferably a mixture of a polar solvent and water wherein the water content is in the rage of 0.5 to 20 % of the total volume of solvent mixture, and most preferably wherein the mixture is a mixture of ethanol and water.

14. A method of producing monomers and/or furfural from biomass comprising the steps of:

o mixing the biomass, a solvent and a zeolite-based solid catalyst forming a first mixture;

o heating the first mixture at a temperature of 120°C or higher but not higher than 300°C to obtain the monomers and/or furfural; and o optionally isolating the obtained monomers and/or furfural; wherein the biomass contains lignin, cellulose and/or hemicellulose and wherein the zeolite-based solid catalyst have pores with a diameter of 0.7nm or smaller but 0.4nm or larger.

15. The method according to claim 14 wherein the first mixture is heated at a

temperature from 150 to 250°C, preferably from 180°C to 240°C, preferably from 200°C to 230°C, more preferably around 220°C.

16. The method according to claim 14 or 15 wherein the solvent is a mixture of at least two polar protic solvents or is a mixture of at least one polar protic solvent and at least one aprotic solvent wherein at least one of the solvents is selected from methanol, ethanol, 1 -propanol, 2-propanol, 1 -butanol, 2-butanol 1,4- dioxane and acetonitrile.

17. The method according to claim 16 wherein the solvent is a mixture of at least two polar protic solvents wherein one polar protic solvent is water and wherein at least one solvent is preferably an alcohol preferably selected from methanol or ethanol more preferably ethanol.

18. The method according to claim 17 wherein the solvent is a mixture of at least one polar protic solvent and at least one aprotic solvent wherein the polar protic solvent is water and wherein the at least one aprotic solvent is a cyclic ether preferably dioxane.

19. The method according to claim 17 or 18 wherein the volume ratio between

water and the alcohol or the aprotic solvent is between 15: 1 to 1 :4, preferably 12: 1 to 5: 1 , more preferably 10: 1 to 8: 1.

20. The method according to any one of claims 14 to 19 wherein the zeolite-based solid catalyst has a Si/Al ratio of 10-50, preferably 12-30, more preferably 12-

15.

21. The method according to any one of claims 14 to 20 wherein the diameter of the pores of the zeolite-based solid catalyst is 0.65nm or smaller but 0.5nm or larger.

22. The method according to any one of claims 14 to 21 wherein the zeolite-based solid catalyst is defined by that the maximum diameter of a sphere that can be included is 0.8nm or smaller, preferably 0.75nm or smaller, more preferably 0.7nm or smaller.

23. The method according to any one of claims 14 to 22 wherein the zeolite-based solid catalyst is essentially free from cavities having a diameter of 1.1 nm or larger, preferably lnm or larger, more preferably essentially free from cavities having a diameter of 0.9nm or larger.

24. The method according to any one of claims 14 to 23 wherein pore diameter or diameter of the pores denotes the maximum size of pores constituting at least 90% or preferably at least 95% of the total pore volume.

25. The method according to any one of claims 14 to 21 wherein the zeolite-based solid catalyst is beta zeolite or zeolite having a BEA framework.

26. The method according to any one of claims 14 to 22 wherein the biomass is lignocellulosic biomass, preferably hardwood or softwood biomass.

27. The method according to any one of claims 14 to 23 wherein the obtained

monomers comprises monophenolic compounds preferably selected from:

28. A composition derived from wood comprising a mixture of monophenolic compounds and furfural.

29. The composition according to claim 25, wherein the mixture of monophenolic compounds comprises the following monophenolic compounds as its major constituents:

30. A composition according to any one of the claims 25 and 26 further comprising esters of levulinic acid, and ethers of sugars, and/or 5-hydroxymethylfurfural.

31. A composition obtainable by the method of any one of the claims 1 to 24.

32. A fuel obtainable by hydroprocessing a composition according to any one of the claims 25 to 28 or a fraction of said compositions.