Methods for the conversion of solid lignocellulosic materials

Abstract

%と51.0wt%。 Conversion of a solid material comprising hemicellulose, cellulose and lignin by the following steps: a) (i) hydrolyzing at least a portion of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution at a temperature of 40°C or less, preferably 30°C or less, wherein the first aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of 15.0% to less than 40.0% by weight relative to the weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution, to give a remaining solid material and a hydrochloric acid-containing, first aqueous hydrolysis product solution; (ii) hydrolyzing at least a portion of the cellulose of the remaining solid material with a second aqueous hydrochloric acid solution at a temperature of 40°C or less, preferably 30°C or less, wherein the second aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of 40.0% to 51.0% by weight relative to the weight of water and hydrochloric acid in such second aqueous hydrochloric acid solution, to give a residue and a hydrochloric acid-containing, second aqueous hydrolysis product solution; (b) - part or all of the hydrochloric acid-containing, first aqueous hydrolysis product solution of step (a); and / or transferring the aqueous hydrochloric acid-containing intermediate product solution containing some or all of the aqueous hydrochloric acid-containing second hydrolysis product solution of step (a) to step (c); and (c) heating at least a portion of the aqueous hydrochloric acid-containing intermediate product solution to a temperature of 60°C or greater to provide a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from such product solution into an extraction solvent.

Description

[Technical field]

[0001] The present invention relates to a method, in particular the present invention relates to a method for the conversion of solid lignocellulosic material. [Background technology]

[0002] In recent years, the use of sustainable resources such as biomass has become increasingly important for the production of compounds for fuel and chemical applications. Such bio-derived fuels and chemicals are sometimes also referred to as "biofuels" and "biochemicals". One advantage of using sustainable biomass resources is that the C02 balance is more favorable compared to traditional feedstocks of mineral origin. The production of biofuels and biochemicals from non-edible sustainable resources such as solid lignocellulosic materials is preferred because non-edible solid lignocellulosic materials do not compete with food production.

[0003] 5-(Chloromethyl)furfural (CMF) is a valuable intermediate in the production of biofuels and biochemicals. It can be used, for example, as an intermediate in the production of 5-(hydroxymethyl)furfural (HMF), 5-(alkoxymethyl)furfural, and / or 2,5 di-formylfuran (DFF) (also called 2,5-furandicarbaldehyde).

[0004] 2,5-di-formylfuran can serve as a monomer or crosslinker in the preparation of polymers, but can also be used as a binder for certain metals, as a corrosion inhibitor, or as a surface treatment agent. It can also be used as a precursor of 2,5-furan-dicarboxylic acid (FDCA), a monomer building block for the production of bio-based polyethylene furanoates (PEFs). 2,5-di-formylfuran can be produced from 5-(chloromethyl)furfural, for example, as described in French Patent Application Publication No. 3008409. The oxidation of 5-chloromethylfurfural to 2,5-diformylfuran is described in an article by Vicente et al. entitled "Oxidation of 5-chloromethylfurfural to 2,5-diformylfuran", published in Molecules (2017), Vol. 22, p. 329 et seq.

[0005] The compounds 5-(alkoxymethyl)furfural are of interest for both fuel (additive) and chemical applications. For example, 5-(ethoxymethyl)furfural (EMF) is an interesting diesel fuel additive. Furthermore, for example, 5-(methoxymethyl)furfural (MMF) is an important intermediate in the production of 2,5-furan-dicarboxylic acid (FDCA). Estonian Patent Application Publication No. 2013 / 0003 describes a method for the preparation of 5-(alkoxymethyl)furfural from 5-(chloromethyl)furfural or 5-(bromomethyl)furfural.

[0006] It would therefore be desirable to have a process that would allow for the production of 5-(chloromethyl)furfural from solid lignocellulosic materials.

[0007] An article by Mascal et al. entitled "Dramatic Advancements in the Saccharide to 5-(Chloromethyl)furfural Conversion Reaction" published in ChemSusChem (2009), Vol. 2, pp. 859-861, describes a method for the conversion of corn stover to 5-(chloromethyl)furfural in a two-phase reactor, for example, by heating powdered corn stover, concentrated hydrochloric acid (HCl) and 1,2-dichloroethane at 80° C. with vigorous stirring.

[0008] The method described by Mascal has the disadvantage, when solid lignocellulosic material is used as feedstock, that not only the cellulosic fraction, which is the main CMF precursor, but also the fractions that cannot give CMF, are heated in concentrated HCl.

[0009] Solid lignocellulosic materials include not only cellulose, but also hemicellulose and lignin. Under the conditions of the Mascal process described above, hemicellulose is converted into various pentoses (C5 saccharides) and hexoses (C6 saccharides). These pentoses and hexoses have different reactivities and may result in various by-products such as furfural, 5-(hydroxymethyl)furfural, levulinic acid, formic acid and humins. Furthermore, these pentoses and hexoses and / or these by-products can in turn react with lignin in various types of reactions, resulting in further unhelpful by-products and / or pollutants. Depending on market demand, the production of some by-products, such as furfural, may be economically interesting. However, the production of unhelpful by-products and / or pollutants is undesirable.

[0010] Different types of solid lignocellulosic materials can vary greatly in their composition and structure. For example, waste paper has a different composition than agricultural waste, which has a different composition than forest products and / or forest residues, such as wood and wood-related materials. Hardwoods, for example, have large amounts of cellulose, but solid lignocellulosic materials, such as wheat straw, have more hemicellulose. Softwoods tend to contain more lignin (usually about 27-29% by weight based on the total weight of the softwood) than hardwoods (usually about 22% by weight based on the total weight of the hardwood). Lignocellulosic materials can also vary in particle size and brittleness. Furthermore, the structure and / or composition of lignocellulosic materials can vary depending on the part of the plant (e.g., bark, roots or branches), age, stage of development or other state of the plant's life.

[0011] With respect to the hydrolysis process, differences in hemicellulose composition are of primary importance: hardwood hemicellulose may contain primarily xylose (a furfural precursor), whereas softwood hemicellulose contains very little xylose. Thus, complete hydrolysis of these wood types can yield large amounts of furfural in the case of hardwood feedstocks and very little in the case of softwood feedstocks.

[0012] Furthermore, different types of wood may contain different amounts of cellulose and hemicellulose. Furthermore, different types of wood may contain different types and amounts of non-glucose units in the hemicellulose fraction, as explained in Table 5-1 in the Fengel and Wegener handbook entitled "Wood: Chemistry, ultrastructure, reactions" (1984) published by Walter De Gruyter, Berlin-New York. Non-glucose units are monomer units other than glucose-based monomer units.

[0013] On the one hand, some non-glucose units that may be present in the hemicellulose fraction of solid lignocellulosic materials, such as mannose, fructose, and sorbose, can react to produce 5-(chloromethyl)furfural. (See, for example, the article by Gao et al., entitled "Efficient One-Pot Synthesis of 5-Chloromethylfurfural (CMF) from Carbohydrates in Mild Biphasic Systems," published in Molecules (2013), vol. 18(7), pp. 7675-7685). On the other hand, other non-glucose units that may be present in the hemicellulose fraction of solid lignocellulosic materials can have different reactivities and result in different by-products. Depending on the market demand for such by-products, such as furfural, such by-products may or may not be desirable.

[0014] The availability of different types of lignocellulosic materials may vary from country to country and even between regions of the same country. Furthermore, the availability of types of lignocellulosic materials may vary from season to season during the year. The method described by Mascal lacks flexibility with respect to the type of solid lignocellulosic material used as feedstock. Whatever solid lignocellulosic material is used as feedstock, all fractions of the lignocellulosic material are heated at high temperatures in the presence of concentrated hydrochloric acid as described above. Even if such solid lignocellulosic materials contain large hemicellulose fractions and / or large lignin fractions, this may lead to significant production of non-beneficial by-products.

[0015] When converting the entire solid lignocellulosic material in the process described by Mascal, valuable energy, reactants and reactor size are wasted in generating non-useful by-products. In industrial-scale processes, these non-useful by-products must then be repeatedly removed, making the entire process complex, costly and economically unattractive. Furthermore, some of these by-products may have similar solubility as 5-(chloromethyl)furfural in solvents such as 1,2-dichloroethane used in the Mascal process, further complicating the isolation and purification of 5-(chloromethyl)furfural and further reducing the economic attractiveness of the process.

[0016] Also, the residual lignin produced in the Mascal process is disadvantageous. Residual lignin from biomass decomposition processes is usually incinerated. However, the residual lignin obtained after treatment with concentrated hydrochloric acid at high temperatures in the process described by Mascal may contain high concentrations of covalently bound chlorine. This makes such residual lignin produced in the Mascal process less attractive for incineration.

[0017] Furthermore, the Mascal process requires the comminution of the solid lignocellulosic feedstock and very vigorous stirring of the reaction mixture. Although particle size reduction of the solid lignocellulosic feedstock to a powder and vigorous stirring of the reaction mixture are relatively easy to handle on a laboratory scale, handling large amounts of feedstock on an industrial scale can be very cumbersome and energy intensive, especially when stirring at high temperatures under highly corrosive conditions of concentrated hydrochloric acid.

[0018] WO 2014 / 066746 describes a method for producing 5-(halomethyl)furfural, including 5-(chloromethyl)furfural, by acid-catalyzed conversion of biomass. It is described that pretreatment of biomass can help to make sugars in the biomass more available by disrupting the crystalline structure of cellulose and hemicellulose and decomposing lignin structures (if present). Typical pretreatments mentioned include mechanical treatment (e.g., cutting, pulverizing, grinding), concentrated acid and dilute acid. In the illustrated method, biomass containing cellulose and / or hemicellulose is added to a reactor and contacted with a solvent and aqueous hydrochloric acid. Reaction temperatures between 30° C. and 300° C. are mentioned. However, also in this method, hemicellulose, cellulose and lignin are all present as part of the feedstock. The industrialization of this method thus suffers from the same inconveniences and complexities as the Mascal method.

[0019] It would be an advance in the art to provide a process suitable for the conversion of solid lignocellulosic material to 5-(chloromethyl)furfural that is flexible in producing by-products such as furfural depending on market demand. Such versatility can also allow for assurance that the highest efficiency can be obtained based on the amount of wood available. Furthermore, it would be advantageous if such a process could be operated in a continuous or semi-continuous manner and / or could be operated on an industrial scale in an economically attractive manner. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] French Patent Application Publication No. 3008409 [Patent Document 2] Estonian Patent Application Publication No. 2013 / 0003 [Patent Document 3] International Publication No. 2014 / 066746 [Patent Document 4] U.S. Patent Application Publication No. 20150275320 [Patent Document 5] U.S. Patent No. 2,778,751 [Patent Document 6] European Patent No. 1878480 [Patent Document 7] International Publication No. 2015 / 136044 [Patent Document 8] International Application No. PCT / EP2017 / 071914 [Patent Document 9] U.S. Patent No. 2,778,751 [Patent Document 10] International Publication No. 2012 / 061085 [Patent Document 11] U.S. Patent No. 2,945,777 [Non-patent literature]

[0021] [Non-Patent Document 1] Vicente et al. "Oxidation of 5-chloromethylfurfural to 2,5-diformylfuran" Molecules (2017) Vol. 22, p. 329ff. [Non-Patent Document 2] Mascal et al., “Dramatic Advancements in the Saccharide to 5-(Chloromethyl)furfural Conversion Reaction,” ChemSusChem (2009), vol. 2, pp. 859-861. [Non-Patent Document 3] "Wood: Chemistry, ultrastructure, reactions" (1984) Table 5-1 in the handbook of Fengel and Wegener, Walter De Gruyter, Berlin-New York [Non-Patent Document 4] Gao et al. “Efficient One-Pot Synthesis of 5-Chloromethylfurfural (CMF) from Carbohydrates in Mild Biphasic Systems” Molecules (2013), vol. 18(7), pp. 7675-7685 [Non-Patent Document 5] "Isothermal Absorption of Hydrogen Chloride," pages 1-2, "The Dietrich Process Systems" website: URL: https: / / www.dedietrich.com / en / solutions-and-products / halide-treatment / hcl-treament / absorption-hydrogen-chloride / isothermal Summary of the Invention [Means for solving the problem]

[0022] Such a method has now been obtained using the method according to the invention. The invention therefore comprises the following steps: a) (i) hydrolyzing at least a portion of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution at a temperature of 40° C. or less, preferably 30° C. or less, the first aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 15.0% by mass or more and less than 40.0% by mass relative to the mass of water and hydrochloric acid in the first aqueous hydrochloric acid solution, to obtain a first aqueous hydrolysis product solution containing the remaining solid material and hydrochloric acid; (ii) hydrolyzing at least a portion of the cellulose in the remaining solid material with a second aqueous hydrochloric acid solution at a temperature of 40° C. or less, preferably 30° C. or less, the second aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 40.0% by mass to 51.0% by mass relative to the mass of water and hydrochloric acid in the second aqueous hydrochloric acid solution, to obtain a residue and a hydrochloric acid-containing second aqueous hydrolysis product solution. converting a solid material comprising hemicellulose, cellulose and lignin by (b) - a part or the whole of the hydrochloric acid-containing aqueous first hydrolysis product solution of step (a); and / or - a part or the whole of the hydrochloric acid-containing second aqueous hydrolysis product solution of step (a) transferring the aqueous intermediate product solution containing hydrochloric acid to step (c); and (c) heating at least a portion of the hydrochloric acid-containing, intermediate aqueous product solution to a temperature of at least 60° C. to provide a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from such product solution into an extraction solvent. The present invention provides a method comprising:

[0023] The process according to the invention is advantageously versatile in converting different types of solid lignocellulosic materials into 5-(chloromethyl)furfural and can be readily scaled up to an economically attractive industrial scale process. The process can further be suitably operated in a continuous or semi-continuous mode, as described in more detail below.

[0024] The process according to the invention advantageously makes it possible to select for heating in step (c) part or all of the hydrochloric acid-containing, aqueous first hydrolysis product solution and / or the hydrochloric acid-containing, aqueous second hydrolysis product solution of step (a) depending on the type, structure and / or composition of the lignocellulosic material used as feedstock to the process, thereby making it possible to adjust the amount and type of 5-(chloromethyl)furfural and by-products generated depending on the market demand for such by-products, such as furfural.

[0025] More advantageously, it allows a better utilization of the sugars contained in the wood: if so desired, mainly C6 saccharides can be diverted to step (c), making it possible to use at least a portion of the C5 saccharides, such as xylose, to produce other valuable products, such as xylitol.

[0026] In the method according to the invention, lignin can be successfully removed before the production of 5-(chloromethyl)furfural. Moreover, undesired impurities mixed in the lignin can also be removed in this way. Moreover, if so desired, the first hydrolysis product derived from hemicellulose can also be successfully removed before the production of 5-(chloromethyl)furfural. In this way, the inconveniences and complexities of the Mascal method and the method described in WO 2014 / 066746 can be avoided.

[0027] Furthermore, step (a) of the process according to the invention can be carried out at lower temperatures than the Mascal process or the process described in WO 2014 / 066746. In this way, the amount of heat expended in producing non-useful by-products can be reduced. The residual lignin recovered from the process according to the invention can be expected to have less covalently bound chlorine.

[0028] Moreover, the method according to the invention allows a very economical separation of hydrochloric acid. Hydrochloric acid is a cumbersome and expensive compound to separate from saccharides, such as saccharides in the aqueous hydrolysate solution. If the aqueous hydrochloric acid-containing hydrolysate solution is transferred directly to step (c) without separating the hydrochloric acid, the expensive and cumbersome process step for removing the hydrochloric acid is no longer necessary when isolating the saccharides and can be avoided. After conversion of at least a portion of the saccharides in the aqueous hydrolysate solution to 5-(chloromethyl)furfural, such 5-(chloromethyl)furfural can be isolated in an easy and economically attractive manner by extraction as mentioned in step (c). As will be explained in more detail below, the extraction of 5-(chloromethyl)furfural from the product solution into the extraction solvent of step (c) advantageously further increases the economic attractiveness of the method.

[0029] The 5-(chloromethyl)furfural may or may not be separated from the extractant, and may then be suitably used in a subsequent step, with or without the presence of the extractant, to produce 2,5-di-formylfuran (DFF), 5-(hydroxymethyl)furfural (HMF) and / or 5-(alkoxymethyl)furfural, such as 5-(methoxymethyl)furfural (MMF) or 5-(ethoxymethyl)furfural (EMF).

[0030] The method of the present invention is illustrated by the following diagram: [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 illustrates a first cycle of the process according to the invention, starting at time "t", where step (a) is carried out semi-continuously in multiple reactors and step (c) of the process is carried out continuously in a countercurrent two-phase continuous flow reactor in the presence of an extraction solvent. [Diagram 2] FIG. 2 illustrates a second cycle of the same method as in FIG. 1, starting at time “t+8 hours.” DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Step (a) involves the conversion of a solid material containing hemicellulose, cellulose and lignin. Suitably, such solid material is a solid lignocellulosic material.

[0033] Cellulose (also referred to herein as cellulosic material) is understood herein to be a homopolysaccharide comprising glucose-based monomeric units, such as cellobiose.

[0034] Hemicelluloses (also referred to herein as hemicellulosic materials) are also polysaccharides, but are distinct from cellulose. Hemicelluloses may contain pentose monomer units, such as xylose and arabinose, hexose monomer units, such as glucose and mannose, hexuronic acid and deoxyhexose monomer units. Some hemicelluloses may consist essentially of only one type of monomer unit (e.g., xylan, which contains essentially only xylose), but most hemicelluloses may contain several different types of monomer units (e.g., glucomannan, which contains glucose and mannose).

[0035] The process according to the invention can use a wide variety of solid lignocellulosic materials as feedstock. Examples of solid lignocellulosic materials that may be suitably used in the process of the invention include agricultural waste, such as stover (e.g. corn stover and soybean stover), corn cobs, rice straw, rice husks, oat husks, corn fiber, cereal straw, such as wheat, barley, rye and oat straw; grass; forest products and / or forestry residues, such as wood and wood-related materials, such as sawdust and bark; waste paper; sugar processing residues, such as pomace and beet pulp; or mixtures thereof. More preferably, the solid lignocellulosic material is selected from the group consisting of wood, sawdust, bark, straw, hay, grass, pomace, corn stover, and / or mixtures thereof.

[0036] Preferably, the solid lignocellulosic material is inedible to prevent the process from competing with food production. Most preferably, the solid lignocellulosic material comprises or consists of wood. The wood may comprise softwoods and / or hardwoods and may originate from all types of trees including spruce, pine, willow, larch, oak, birch, poplar, eucalyptus and other trees.

[0037] As explained above, different types of wood may contain different amounts of cellulose and hemicellulose. Furthermore, different types of wood may contain different types and amounts of non-glucose units in the hemicellulose fraction, as explained in Table 5-1 in the Fengel and Wegener handbook entitled "Wood: Chemistry, ultrastructure, reactions" (1984) published by Walter De Gruyter, Berlin-New York. Depending on the market demand for certain by-products, some types of wood may be preferred over others.

[0038] For example, in the method according to the invention, furfural can be advantageously co-produced from xylose. If there is a significant market demand for furfural, the solid lignocellulosic material is preferably wood or wood-related material having 10% by weight (mass percent) or more of xylose units relative to the total weight of non-glucose units in the hemicellulose fraction. Examples of timber types suitable for this purpose include red maple (Acer rubrum), yellow birch (Betula alleghaniensis), silver birch (Betula papyrifera), beech (Betula verrucosa), American beech (Fagus grandifolia), ash (Fraxinus excelsior), Carolina poplar (Populus tremuloides), black locust (Robinia pseudoacacia) and American elm (Ulmus Americana). The hydrochloric acid-containing, first aqueous hydrolysis product solution obtained in step (a) then suitably contains xylose-containing saccharides. When such first aqueous hydrolysis product solution is transferred to step (c), the method according to the invention advantageously allows the simultaneous production of furfural.

[0039] The first hydrolysis product solution is sometimes referred to herein simply as the "first hydrolysate," the "first hydrolysis product," or the "prehydrolysis product."

[0040] Feedstocks containing epimers of glucose, such as mannose or galactose, in the hemicellulose fraction can increase the yield of 5-(chloromethyl)furfural relative to the yield of 5-(chloromethyl)furfural obtained based on the cellulosic fraction alone. In such cases, the lignocellulosic material is preferably wood or wood-related material that contains 10% or more by weight of mannose units relative to the total weight of non-glucose units in the hemicellulose fraction. Examples of timber types suitable for this purpose include balsam fir (Abies balsamea), European larch (Larix decidua), Tama pine (Larix laricina), Norway spruce (Picea abies), Canada spruce (Picea glauca), Scots pine (Pinus sylvestris) and Canadian hemlock (Tsuga canadensis).

[0041] When it is desired to produce 5-(chloromethyl)furfural and minimize the generation of by-products, lignocellulosic materials containing small amounts of hemicellulose can preferably be used.

[0042] Advantageously, the stepwise conversion of step (a) allows the use of any type of lignocellulosic material. If in step (b) no first hydrolysis product solution is transferred and only a part or the whole of the hydrochloric acid-containing, second aqueous hydrolysis product solution is transferred, advantageously the saccharides fed to step (c) mainly comprise glucose-based saccharides.

[0043] The solid lignocellulosic material may conveniently be washed, dried, fired, roasted and / or particle size reduced before it is used as a feedstock in step (a). The solid lignocellulosic material may conveniently be provided or present in a variety of forms including chips, pellets, powder, chunks, briquettes, crushed particles, milled particles, ground particles, or combinations of two or more thereof. When the solid lignocellulosic material is wood it may for example be provided or present in the form of wood flour, wood chips, wood pellets, wood briquettes, wood chunks, or combinations of two or more thereof.

[0044] Preferably, in the present process the solid lignocellulosic material is a solid lignocellulosic material the particles of which prior to step (a) preferably have a particle size of at least P16A and at most P100, preferably P45A or P45B, according to the European standard EN 14961-1 for solid biofuels. Alternatively, the solid lignocellulosic material in the present process is preferably a solid lignocellulosic material the particles of which prior to step (a) preferably have a minimum dimension of 3 mm and a maximum dimension of 100 mm, more preferably between 8 mm and 45 mm, measured according to the European standard EN 15149 for solid biofuels.

[0045] When the solid lignocellulosic material is wood, such wood is most preferably provided or present in the form of wood chips. When the solid lignocellulosic material comprises grass, pomace and / or stover, such grass, pomace and / or stover are most preferably provided or present in the form of pellets. Such pellets advantageously provide unorganized biomass such as grass, pomace and / or stover with a desired morphology. Such morphology can advantageously limit the breakdown of material inside the reactor during hemicellulose and cellulose hydrolysis, which may otherwise cause undesired pressure losses.

[0046] The solid lignocellulosic material is preferably loaded into a vertical tubular reactor, which may suitably be equipped with a discharge opening that can be opened or closed, allowing the remaining residue of the lignocellulosic material to be discharged after processing. Preferably, such a discharge opening is located at the bottom of such a reactor.

[0047] The solid lignocellulosic material may therefore be fed to the reactor in any manner known to be suitable to one skilled in the art. The lignocellulosic material may be fed to the reactor, for example, by a feed hopper, a conveyor belt, a screw feeder or a combination thereof. The lignocellulosic material may suitably be charged to such reactors in a batchwise, semi-continuous or continuous manner. The lignocellulosic material may be charged to the top of such reactors, through one or more inlets located at the bottom of such reactors and / or through one or more side inlets located in the reactor wall.

[0048] Different types of reactors can be used. The process according to the invention can be carried out in any reactor known to those skilled in the art as suitable for hydrolysis reactions. Such reactors are also referred to herein as "hydrolysis reactors".

[0049] Preferably, the process is carried out in one or more reactors, described as the Bergius-Rheinau process. Preferably, such reactors comprise cylindrical vessels with an axis arranged in a substantially vertical or substantially horizontal manner. Preferably, the reactors are substantially vertical tubular reactors. If so desired, the reactors may be slightly inclined, for example as described in US Patent Publication No. 20150275320. Preferably, the reactors are conically tapered at the top and bottom. The ratio of diameter to height may suitably be in the range of ≧1:10 (diameter:height) to ≦1:4 (diameter:height). The reactors may suitably be equipped with a discharge opening, which may be opened or closed, allowing the discharge of residual lignin after processing. Preferably, such a discharge opening is located at the bottom of such a reactor. Examples of suitable reactors include, for example, reactors described in U.S. Pat. No. 2,778,751, EP 1,878,480, WO 2015 / 136044 and unpublished international application PCT / EP2017 / 071914. The aqueous hydrochloric acid solution can advantageously be flowed through such hydrolysis reactors in a continuous, intermittent or semi-continuous manner.

[0050] Step (a) is preferably carried out in a plurality of reactors, more preferably in a plurality of reactors connected in series. Such a plurality of reactors is also referred to herein as a reactor series. Preferably, step (a) is carried out in a plurality of reactors connected in series (also referred to as a column), as described in the Bergius-Rheinau process. Examples of the Bergius-Rheinau process include, for example, the Bergius-Rheinau process described in US Pat. No. 2,778,751, preferably modified by Riehm. Step (a) can also be carried out as described in WO 2012 / 061085.

[0051] Preferably, step (i) of step (a) is preceded by a charging step, as described in detail above, in which solid lignocellulosic material is charged to the reactor.

[0052] Step (i) comprises hydrolysing at least a portion of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution, suitably at a temperature of 40° C. or less, preferably 30° C. or less, the first aqueous hydrochloric acid solution having a hydrochloric acid concentration ranging from 15.0% to less than 40.0% by weight relative to the weight of water and hydrochloric acid in said first aqueous hydrochloric acid solution. Such step (i) suitably provides a first hydrolysis product solution, in which further solid material remains. Such remaining solid material may suitably still comprise cellulose and lignin.

[0053] Hydrolyzing, respectively, is understood herein as the breaking of bonds between saccharide units in polysaccharides such as hemicellulose or cellulose to give monosaccharides, disaccharides and / or oligosaccharides. (Oligosaccharides are understood herein as saccharide chains containing in the range of 3-10 monosaccharide units.) The products of hydrolysis are also referred to as "hydrolysates."

[0054] The hydrolysis of hemicellulose is also known as "prehydrolysis" and the product of the hydrolysis of hemicellulose is also known as "prehydrolysate". Step (i) is therefore also referred to herein as "prehydrolysis" or "prehydrolyzing". The first hydrolysis product solution obtained by the hydrolysis of hemicellulose in step (i) may also be referred to herein as "prehydrolysis product", "prehydrolysis product solution" or "hemicellulose hydrolysis product solution". The solid material remaining after the hydrolysis of hemicellulose in step (i) may also be referred to herein as "prehydrolyzed solid material".

[0055] As explained by the hydrochloric acid concentration, the conditions of the pre-hydrolysis in step (i) are less stringent than the conditions of the main hydrolysis in step (ii) below. Under the conditions of step (i), hemicellulose can be selectively hydrolyzed. Hydrolysis of hemicellulose can already be achieved by simply contacting the solid lignocellulosic material with the first aqueous hydrochloric acid solution. For best results, the solid material is preferably immersed in the first aqueous hydrochloric acid solution. Such first aqueous hydrochloric acid solution may or may not contain saccharides.

[0056] Step (i) may be carried out over a wide range of pressures. Conveniently, a pressure of about 0.1 megapascals (corresponding to about 1 bar) may be applied. All pressures herein are absolute pressures.

[0057] High temperatures are not necessary. Thus, step (i) can be conveniently carried out at about room temperature (20° C.). For practical purposes, step (i) is preferably carried out at a temperature of 0° C. or higher, preferably 30° C. or lower. At temperatures above 40° C., it is believed that cellulose begins to become hydrolyzed and thus the selectivity for hemicellulose hydrolysis may decrease. Furthermore, such hydrolysis of cellulose may cause low yields in step (ii).

[0058] The hydrochloric acid concentration of the first hydrochloric acid aqueous solution shown above is based on the mass of water and hydrochloric acid contained in the first hydrochloric acid aqueous solution. The first hydrochloric acid aqueous solution preferably has a hydrochloric acid concentration in the range of 34.0 mass% to 39.9 mass%, more preferably 36.0 mass% to 39.0 mass%, based on the mass of water and hydrochloric acid contained in the first hydrochloric acid aqueous solution.

[0059] The combination of pressure, temperature and hydrochloric acid concentration can be optimized to achieve optimal selectivity in the hydrolysis of hemicellulose. Preferably, the combination of pressure, temperature and hydrochloric acid concentration is applied such that hydrochloric acid is completely dissolved in solution as hydrogen ions and chloride ions. More preferably, the combination of pressure, temperature and hydrochloric acid concentration is such that no molecular hydrochloric acid remains in solution. Further guidance in this respect can be found, for example, by plotting the boiling point of an aqueous hydrochloric acid solution as a function of hydrochloric acid concentration at the applied pressure. Such plots are provided, for example, on the website of "The Dietrich Process Systems" in "Isothermal Absorption of Hydrogen Chloride", pages 1-2, and can be found on the Internet at the URL: https: / / www.dedietrich.com / en / solutions-and-products / halide-treatment / hcl-treament / absorption-hydrogen-chloride / isothermal on January 30, 2018. It is most preferred that the combination of pressure, temperature and hydrochloric acid concentration applied during step (i) does not exceed the boiling point.

[0060] For practical purposes, preferably at a pressure of about 0.1 megapascals, suitably the temperature (° C.) multiplied by the concentration of hydrochloric acid in weight percent (wt %) is less than 1000 relative to the weight of water and hydrochloric acid contained in the first aqueous hydrochloric acid solution, as illustrated below by formula (I): Temperature (℃) × Concentration (mass%) ≦1000 (I)

[0061] Without wishing to be bound by any kind of theory, it is believed that during the prehydrolysis of step (i), mainly the hemicellulose present in the solid material can be hydrolyzed, which can suitably result in a first hydrolysis product solution that can comprise or consist of an aqueous solution containing hydrochloric acid and a mixture of mono-, di- and oligosaccharides of pentoses (i.e., C5 saccharides, which are sugars whose molecules contain 5 carbon atoms) and hexoses (i.e., C6 saccharides, which are sugars whose molecules contain 6 carbon atoms).

[0062] The first hydrolysis product solution may comprise, for example, pentose monosaccharides, hexose monosaccharides, pentose disaccharides, hexose disaccharides, and pentose hexose disaccharides, pentose oligosaccharides, hexose oligosaccharides, and / or oligosaccharides of a mixture of pentoses and hexoses.Suitably, the first hydrolysis product solution may comprise one or more compounds selected from the group consisting of glucose, fructose, mannose, galactose, arabinose, xylose, sucrose, cellobiose, ribulose, ribose, lyxose, allose, altrose, glucose dimers (such as maltose), glucose trimers, cellotriose, maltotriose, cellodextrins, dextrins, xylan oligosaccharides, mannan oligosaccharides, arabinan oligosaccharides, and oligofructans. More suitably, the first hydrolysis product solution may comprise at least one compound selected from the group consisting of mannose, glucose, galactose, arabinose and xylose, or dimers or oligomers thereof.

[0063] Preferably, the first hydrolysis product solution comprises saccharides (including mono-, di- and / or oligosaccharides) in a total amount of 2% by weight or more, more preferably 5% by weight or more, even more preferably 10% by weight or more, most preferably 20% by weight or more of saccharides, based on the total weight of the prehydrolysis product solution. The upper limit for the saccharide content in the first hydrolysis product solution is formed by the solubility of the saccharides in the solution. For practical purposes, the first hydrolysis product solution may suitably comprise saccharides (including mono-, di- and / or oligosaccharides) in a total amount of 45% by weight or less, more preferably 40% by weight or less of saccharides, based on the total weight of the prehydrolysis product solution.

[0064] In addition to saccharides, the first hydrolysis product solution may suitably contain hydrochloric acid. Preferably, the first hydrolysis product solution may have a hydrochloric acid concentration in the range of ≧1.0% to ≦40.0% by weight, more preferably in the range of ≧10.0% to ≦39.0% by weight, based on the combined weight of hydrochloric acid and water in the first hydrolysis product solution.

[0065] The remaining solid material, also referred to as prehydrolyzed solid material, may suitably comprise mainly lignin and cellulose. Preferably, the remaining solid material comprises only small amounts or essentially no hemicellulose. Preferably, the hemicellulose content of the solid material used as feedstock to the process is reduced by at least 85% by weight, more preferably at least 95% by weight, preferably essentially 100% by weight. That is, preferably at least 85% by weight, more preferably at least 95% by weight, most preferably essentially 100% by weight of the hemicellulose in the solid material used as feedstock is hydrolyzed in step (i). The remaining solid material may thus comprise not more than 10% by weight, more preferably not more than 5% by weight, most preferably not more than 1% by weight of the hemicellulose present in the solid material used as feedstock. Most preferably, the remaining solid material is essentially free of hemicellulose.

[0066] Step (ii) comprises hydrolyzing at least a portion of the cellulose of the prehydrolyzed solid material with a second aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 40.0% to 51.0% by weight, suitably relative to the weight of water and hydrochloric acid in such second aqueous hydrochloric acid solution, at a temperature of 40° C. or less, preferably 30° C. or less. Step (ii) suitably provides a second hydrolysis product solution and a residue.

[0067] The second hydrolysis product solution is sometimes referred to herein simply as the "second hydrolysate", the "second hydrolysis product" or the "main hydrolysis product".

[0068] The hydrolysis of cellulose is also known as "main hydrolysis", and the product of the hydrolysis of cellulose is also known as "main hydrolysate". Step (ii) may therefore also be referred to herein as "main hydrolysis", "further hydrolysis" or "further hydrolysis". The second hydrolysis product solution obtained by the hydrolysis of cellulose in step (ii) may be referred to herein as "main hydrolysis product", "main hydrolysis product solution", "final hydrolysis product solution" or "cellulose hydrolysis product solution".

[0069] During such primary hydrolysis, a substantial portion of the remaining bonds between the saccharide units in the remaining polysaccharides in the remaining solid material are hydrolyzed. Most preferably, essentially all of the remaining bonds between the saccharide units in the remaining polysaccharides are broken, although the benefits of the invention can also be obtained if some of the bonds between such saccharide units remain intact.

[0070] The hydrolysis of cellulose in the remaining solid material in step (ii) can already be achieved by simply contacting the remaining solid material with a second aqueous hydrochloric acid solution. For best results, the remaining solid material is preferably immersed in a second aqueous hydrochloric acid solution. Such a second aqueous hydrochloric acid solution may or may not contain saccharides as described below.

[0071] Step (ii) may be carried out over a wide range of pressures. Conveniently, a pressure of about 0.1 megapascals (corresponding to about 1 bar) may be applied.

[0072] Conveniently, step (ii) may be carried out at about ambient temperature (20° C.). For practical purposes, step (ii) is preferably carried out at a temperature in the range of from about 0° C. to about 30° C.

[0073] Preferably, the second aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of 41.0 mass % or more and 45.0 mass % or less with respect to the total mass of water and hydrochloric acid in the second aqueous hydrochloric acid solution.

[0074] The residue may suitably comprise mainly lignin. Preferably, the residue comprises only small amounts or essentially no hemicellulose and only small amounts or essentially no cellulose. Preferably, the cellulose content of the remaining solid material (used at the start of step (iii)) has been reduced by at least 85% by weight, more preferably at least 95% by weight, preferably essentially 100% by weight. That is, preferably at least 85% by weight, more preferably at least 95% by weight, most preferably essentially 100% by weight of the cellulose in the remaining solid material is hydrolyzed in step (iii). The residue may thus comprise no more than 10% by weight, more preferably no more than 5% by weight, most preferably no more than 1% by weight of the cellulose present in the remaining solid material. Most preferably, the residue is essentially free of cellulose and essentially free of hemicellulose. The residue may further comprise hydrochloric acid.

[0075] The second hydrolysis product solution may suitably comprise or consist of an aqueous solution containing hydrochloric acid and primarily glucose saccharides.

[0076] The second hydrolysis product solution may contain saccharides (including mono-, di- and / or oligosaccharides) in a total amount of 2% by weight or more of saccharides, more preferably 5% by weight or more of saccharides, even more preferably 10% by weight or more of saccharides, and possibly even 20% by weight or more of saccharides, based on the total weight of the second hydrolysate solution. The upper limit of the saccharide content in the second hydrolysis product solution is formed by the solubility of the saccharides in the solution. For glucose, a solubility of 909 grams of glucose per kilogram of water at 25°C has been reported. For practical purposes, the second hydrolysis product solution may suitably contain saccharides (including mono-, di- and / or oligosaccharides) in a total amount of 45% by weight or less of saccharides, more preferably 40% by weight or less of saccharides, based on the total weight of the second hydrolysate solution.

[0077] Most preferably, the second hydrolysate solution comprises a total amount of saccharides in the range of 5% to 10% by weight, based on the total weight of the second hydrolysate solution.

[0078] The second hydrolysis product solution may for example comprise glucose monosaccharides, glucose disaccharides, and glucose oligosaccharides.Suitably, the second hydrolysis product solution may comprise one or more compounds selected from the group consisting of glucose and cellobiose.

[0079] The second hydrolysis product solution may contain some pentose sugars (C5 saccharides), but preferably contains little or no C5 saccharides. Preferably, the second hydrolysis product solution contains a total amount of C5 saccharides that is 20.0% or less by weight, more preferably 10.0% or less by weight, even more preferably 5.0% or less by weight, even more preferably 1.0% or less by weight, and most preferably 0.1% or less by weight, based on the total weight of saccharides in the second hydrolysis product solution.

[0080] In addition to the saccharide, the second hydrolysis product solution suitably comprises hydrochloric acid. Preferably, the second hydrolysis product solution has a hydrochloric acid concentration in the range of 20.0% or more, more suitably 30.0% or more and 50.0% or less, more suitably 45.0% or less, more preferably 38.0% or more and 43.0% or less by weight based on the weight of the combined hydrochloric acid and water.

[0081] Preferably, step (a) comprises the steps of: - step (i), in which the solid material is present in a stationary phase in a reactor, the solid material being in contact with a mobile phase moving through such reactor, the mobile phase comprising a zone or zones comprising one or more portions of at least the first aqueous hydrochloric acid solution; and / or - step (ii), in which the remaining solid material is present in a stationary phase in a reactor and in which the remaining solid material is in contact with a mobile phase moving through said reactor, said mobile phase comprising at least a zone comprising one or more portions of the second aqueous hydrochloric acid solution, preferably said mobile phase being a semi-continuous, discontinuous or continuous mobile phase.

[0082] More preferably, step (a) is carried out in multiple reactors: - in step (i), one or more portions of the first aqueous hydrochloric acid solution are transferred from one reactor to another and contact the fixed, possibly already partially pre-hydrolyzed, solid material present in the two or more reactors; and / or - in step (2), one or more portions of the second aqueous hydrochloric acid solution are transferred from one reactor to another and contacted with the fixed, optionally already partially further hydrolyzed remaining solid material present in the two or more reactors. More preferably, the first aqueous hydrochloric acid solution is contacted countercurrently with the optionally partially pre-hydrolyzed solid material and / or the second aqueous hydrochloric acid solution is contacted countercurrently with the optionally partially further hydrolyzed remaining solid material.

[0083] In step (i) of step (a), the portion or portions of the first aqueous hydrochloric acid solution may conveniently form a plug or liquid column, optionally in combination with other fluids, which is preferably moved continuously or semi-continuously through a number of reactors, each reactor containing a certain amount of immobilized solid material, optionally already partially prehydrolyzed. Such solid material is suitably a solid lignocellulosic material as described above. When step (i) is carried out in countercurrent, the portion or portions of the fresh first aqueous hydrochloric acid solution may conveniently be fed to a reactor holding a solid material already partially to fully prehydrolyzed. Saccharides may be absorbed from such already partially prehydrolyzed solid material, and the portion or portions of the first aqueous hydrochloric acid solution (now suitably containing some saccharides) may then be moved from the outlet of such reactor to the inlet of a further reactor, which holds a solid material that has been subjected to less or no prehydrolysis.

[0084] During step (i), hemicellulose is being hydrolyzed and the resulting saccharides are dissolved in the first aqueous hydrochloric acid solution, so that in addition to water and hydrochloric acid, the first aqueous hydrochloric acid solution may or may not contain other compounds, such as dissolved saccharides.

[0085] The first aqueous hydrochloric acid solution (also referred to as fresh first aqueous hydrochloric acid solution) preferably contains only a small amount of dissolved saccharides or more essentially no dissolved saccharides when freshly added to the process. After absorbing saccharides, the first aqueous hydrochloric acid solution is no longer fresh. Such a first aqueous hydrochloric acid solution further containing dissolved saccharides is also referred to herein as "intermediate prehydrolysate solution" or "intermediate prehydrolysate". The intermediate prehydrolysate solution may suitably contain saccharides (such as a mixture of C5 and C6 saccharides) dissolved in the aqueous hydrochloric acid solution. Thus, such an intermediate prehydrolysate solution may suitably be an aqueous hydrochloric acid-containing, intermediate prehydrolysate solution. The intermediate prehydrolysate solution may suitably still be used to contact the solid material to be optionally partially prehydrolyzed, suitably further absorbing saccharides therefrom.

[0086] While being transferred, preferably countercurrently, from one reactor to another, the first aqueous hydrochloric acid solution can suitably absorb more and more saccharide. In this way, the saccharide concentration of the first aqueous hydrochloric acid solution can suitably be gradually increased until a hydrochloric acid-containing, first aqueous hydrolysis product solution is obtained.

[0087] When carried out in countercurrent, step (i) is preferably carried out in a plurality of "x" reactors FR1 to FR X In this case, fresh lignocellulosic material can be introduced and / or present in reactor FR1, and each of the subsequent reactors FR2 to FR X may include partially prehydrolyzed lignocellulosic material, and the degree of prehydrolysis of the lignocellulosic material may vary between reactors FR2 to FR X the first portion or portions of the fresh first aqueous hydrochloric acid solution may be increased in the direction of the last reactor FR X can be introduced into the reactor FR Xfrom the reactor FR1. Suitably, such portion of the first aqueous hydrochloric acid solution can gradually absorb saccharides from the optionally already partially pre-hydrolyzed lignocellulosic material, thereby producing an aqueous hydrochloric acid-containing, pre-hydrolysate solution that can be withdrawn from the reactor FR1. Such an aqueous hydrochloric acid-containing, pre-hydrolysate solution is advantageously richer in saccharides than if step (i) was carried out in a single reactor. X In the above step (ii), a prehydrolyzed solid material can be obtained, which can suitably be used in step (ii).

[0088] In step (ii) of step (a), the portion or portions of the second aqueous hydrochloric acid solution may conveniently form a plug or liquid column, optionally in combination with other fluids, which plug or liquid column moves, preferably continuously or semi-continuously, through a plurality of reactors, each reactor containing a certain amount of fixed remaining solid material that has optionally already been partially further hydrolyzed.

[0089] When step (ii) is carried out in countercurrent, one or more portions of the fresh second aqueous hydrochloric acid solution may be fed to a reactor holding the remaining solid material, which has been advantageously already partially to fully hydrolyzed. Saccharides may be absorbed from such remaining solid material, which has already been partially hydrolyzed, and one or more portions of the second aqueous hydrochloric acid solution (now suitably containing some saccharides) may then be transferred from the outlet of such reactor to the inlet of a further reactor, which holds the remaining solid material which has not been subjected to much or no further hydrolysis.

[0090] During step (ii), the cellulose is hydrolyzed and the resulting saccharides become soluble in the second aqueous hydrochloric acid solution. Thus, in addition to water and hydrochloric acid, the second aqueous hydrochloric acid solution may or may not contain other compounds, such as dissolved saccharides.

[0091] The second aqueous hydrochloric acid solution (also referred to as fresh second aqueous hydrochloric acid solution) preferably contains only small amounts or essentially no dissolved saccharide when freshly added to the process.

[0092] After absorbing the saccharides, the second aqueous hydrochloric acid solution is no longer fresh. Such a second aqueous hydrochloric acid solution further containing dissolved saccharides is also referred to herein as "intermediate hydrolysate solution" or "intermediate main hydrolysate solution". The intermediate hydrolysate solution may suitably contain saccharides (such as a mixture of C5 and C6 saccharides) dissolved in the aqueous hydrochloric acid solution. Thus, such an intermediate hydrolysate solution may suitably be an aqueous hydrochloric acid-containing intermediate hydrolysate solution. The intermediate hydrolysate solution may suitably still be used to contact with a further optionally partially hydrolyzed solid material, suitably absorbing further saccharides therefrom.

[0093] While being transferred, preferably countercurrently, from one reactor to another, the second aqueous hydrochloric acid solution can suitably absorb more and more saccharide. In this way, the saccharide concentration of the second aqueous hydrochloric acid solution can suitably be gradually increased until a hydrochloric acid-containing, second aqueous hydrolysis product solution is obtained.

[0094] When carried out countercurrently, step (ii) preferably comprises a plurality of “y” reactors SR1 to SR y The prehydrolyzed solid material is then fed to reactor SR1 and each of the subsequent reactors SR2 to SR y contains the remaining solid material that has been partially hydrolyzed, and the degree of hydrolysis of the remaining solid material ranges from SR2 to SR y one or more portions of the fresh second aqueous hydrochloric acid solution are fed into the last reactor SR y is introduced into the reactor SR yfrom the reactor SR1. Suitably, this portion of the second aqueous hydrochloric acid solution can gradually absorb saccharides from the remaining solid material, possibly already partially hydrolyzed, thereby producing a hydrochloric acid-containing, first aqueous hydrolysate solution, which can be withdrawn from the reactor SR1. Such a hydrochloric acid-containing, aqueous hydrolysate solution is advantageously richer in saccharides than when step (ii) is carried out in a single reactor. The reactor SR y The residue can be obtained in a reactor SR y can be disposed of from

[0095] Thus, preferably, step (a) comprises: (i) prehydrolyzing a solid lignocellulosic material, the solid lignocellulosic material being contacted in countercurrent flow with a first aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 34.0% to 39.9% by weight, based on the combined weight of water and hydrochloric acid of such first aqueous hydrochloric acid solution, thereby producing a prehydrolyzed lignocellulosic material, and a hydrochloric acid-containing, aqueous prehydrolysis product solution; and / or (ii) further hydrolyzing at least a portion of the prehydrolyzed lignocellulosic material, wherein the prehydrolyzed lignocellulosic material is contacted in countercurrent flow with a second aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 40.0% to 51.0% by weight, based on the combined weight of water and hydrochloric acid of such second aqueous hydrochloric acid solution, thereby producing a residue and a hydrochloric acid-containing, final aqueous hydrolysis product solution.

[0096] Preferably, step (a) is carried out in a plurality of reactors, preferably comprising two or more reactors connected in series, more preferably in the range of from 2 to 16 reactors, even more preferably in the range of from 4 to 8 reactors, most preferably in the range of from 4 to 7 reactors.

[0097] Step (i) may be carried out in a first set of series connected reactors and step (ii) may be carried out in an optionally separate second set of series connected reactors. Suitably, each such set of reactors comprises two or more reactors, preferably from 2 to 10, more preferably from 2 to 8 reactors, most preferably from 2 to 4 reactors.

[0098] However, preferably, steps (i) and (ii) are carried out in a combined set of series connected reactors. Preferably, such combined set of series connected reactors comprises 2 or more reactors, more preferably in the range of 2 to 16 reactors, even more preferably in the range of 4 to 8 reactors, most preferably in the range of 4 to 7 reactors.

[0099] After step (i), the first hydrolysis product solution can be separated from the remaining solid material, and after step (ii), the second hydrolysis product solution can be separated from the residue. This separation can be carried out in any manner known to be suitable by the skilled artisan, for example as described in US 2778751, EP 1878480, WO 2015 / 136044 and unpublished international application PCT / EP2017 / 071914. Preferably, step (i) of step (a) further comprises separating the first hydrolysis product solution from the remaining solid material before further hydrolyzing at least a portion of such remaining solid material with a second aqueous hydrochloric acid solution in step (ii).

[0100] Step (a) can be carried out, for example, as described in US Pat. No. 2,945,777, which describes a method for saccharification of softwood sawdust comprising a prehydrolysis step and a main hydrolysis step. In a first step, the sawdust is subjected to prehydrolysis with hydrochloric acid containing 34-37 mass percent HCl at a temperature of about 15-30° C. for a time sufficient to substantially dissolve the hemicellulose in an amount corresponding to about 22-26 percent of the dried wood material, the solution obtained being subsequently separated from the solid residue. In a second step, the solid residue of said prehydrolysis is treated in a main hydrolysis with hydrochloric acid having an HCl content of about 40-42%, and crystalline glucose is recovered from the sugar syrup obtained in said main hydrolysis.

[0101] The process according to the invention can advantageously be carried out in a continuous or semi-continuous manner. For example, the process can be carried out in a cyclic series of multiple reactors, within each cycle: At least a portion of the hemicellulose of the solid lignocellulosic material (which is a solid material containing hemicellulose, cellulose and lignin) is transferred to reactors FR1 to FR2 of "x". X In the first reactor series, the hydrolyzed and fresh solid lignocellulosic material is introduced into reactor FR1, followed by each of the subsequent reactors FR2 to FR X contains partially prehydrolyzed solid material; one or more portions of the first aqueous hydrochloric acid solution, preferably fresh, are fed to the last reactor FR X The first liquid column containing the first portion of the first aqueous hydrochloric acid solution introduced into the reactor FR X from the reactor FR1 in the countercurrent direction; X and a first hydrolysis product aqueous solution containing hydrochloric acid present in reactor FR1; Thereafter, the hydrochloric acid-containing, first aqueous hydrolysis product solution is withdrawn from reactor FR1; - at least a portion of the cellulose of the prehydrolyzed solid material is transferred to reactors SR1 to SR y The hydrolysis is carried out in the second reactor series, and the remaining solid material is present in reactor SR1, and each of the subsequent reactors SR2 to SRy contains the partially hydrolyzed remaining solid material; one or more portions of the second aqueous hydrochloric acid solution, preferably fresh, are fed to the final reactor SR y The second liquid column containing the first portion of the second aqueous hydrochloric acid solution introduced into the reactor SR y SR1 in the countercurrent direction, and the reactor SR y and a second hydrolysis product aqueous solution containing hydrochloric acid present in a reactor SR1; Thereafter, the hydrochloric acid-containing second aqueous hydrolysis product solution is withdrawn from reactor SR1; after that - Reactors FR1 to FR x-1 Each of the reactors FR2 to FR X Moving into the places occupied by each, - Reactor FR X Each moves to the position occupied by the previous reactor SR1, - Reactors SR1 to SR y-1 are the previous reactors SR2 to SR y Moving into the places occupied by each, - Reactor SR y each moves to the position occupied by the previous reactor FR1, respectively.

[0102] The transfer of one reactor to the place of another reactor is herein preferably understood as one reactor taking over a place in the first or second reactor series mentioned, i.e. the function of another reactor.

[0103] Each cycle is preferably carried out within a period of time referred to as the cycle period, which is suitably the period during which all of the above listed activities are to be carried out, after which each reactor may move one position in the reactor train (i.e. the period between reactor changes).

[0104] The cycle period is preferably in the range of 4 hours or more, more preferably in the range of 6 hours or more and 24 hours or less, more preferably in the range of 12 hours or less. Most preferably, the cycle period is in the range of 7 hours or more and 9 hours or less. For example, the cycle period may be 8 hours.

[0105] Reactors FR2 to FR x The partially prehydrolyzed solid material initially present in may conveniently be obtained during one or more previous cycles.

[0106] Similarly, reactors SR2 to SR y The partially hydrolyzed pre-hydrolyzed solid material initially present in may suitably be obtained during one or more previous cycle periods.

[0107] The reaction conditions, preferences for the lignocellulosic material, the first aqueous hydrochloric acid solution, the second aqueous hydrochloric acid solution, the first hydrolysis product solution, the second hydrolysis product solution, the pre-hydrolyzed solid material, the optional mobile phase and other aspects are all as described herein above.

[0108] The rate at which reactants are fed to the reactor during the cycle period may vary widely, although some reactants, particularly wood, may be fed to the reactor in an intermittent manner. When averaged over a sufficient cycle period, the average mass ratio of the amount of the first aqueous hydrochloric acid solution to the solid (lignocellulosic) material (on a dry basis) is preferably in the range of 0.5:1 (w / m) or more and 10:1 (w / m), or less, more preferably 7:1 (w / m), or less, and most preferably 5:1 (w / m). Similarly, when averaged over a sufficient cycle period, the average mass ratio of the amount of the second aqueous hydrochloric acid solution to the solid (lignocellulosic) material (on a dry basis) is preferably in the range of 0.5:1 (w / m) or more and 10:1 (w / m), or less, more preferably 7:1 (w / m), or less, and most preferably 5:1 (w / m).

[0109] Step (b) is - a part or the whole of the hydrochloric acid-containing aqueous first hydrolysis product solution of step (a); and / or - a part or the whole of the hydrochloric acid-containing second aqueous hydrolysis product solution of step (a) directly or indirectly transferring the aqueous hydrochloric acid-containing intermediate product solution to step (c).

[0110] As explained above, the method advantageously allows for the selection and forwarding to step (c) of only the first hydrolysis product solution, only the second hydrolysis product solution or a combination of the first and second hydrolysis product solutions.

[0111] The selection can be made, for example, on the basis of the lignocellulosic material used as the feedstock and the market demand for the by-products.

[0112] For example, step (b) may suitably comprise transferring directly or indirectly to step (c) the hydrochloric acid-containing, intermediate product aqueous solution which comprises or consists only of part or all of the hydrochloric acid-containing, second aqueous hydrolysis product solution of step (a), whilst suitably not transferring any part or the whole of the hydrochloric acid-containing, first aqueous hydrolysis product solution of step (a).

[0113] By selecting and transferring only the second hydrolysis product solution to step (c), a more constant composition of products (such as 5-(chloromethyl)furfural) and by-products resulting in step (c) can be advantageously obtained. Such a constant composition of products and by-products is desirable when product purification and by-product removal are scaled up to industrial scale. Suitably, by heating only the hydrochloric acid-containing, second hydrolysis product aqueous solution in the absence of the first hydrolysis product solution and in the absence of lignin to a temperature of 60° C. or higher, preferably 70° C. or higher, the generation of hemicellulose-derived C5 and C6 saccharides and / or by-products from lignin can be reduced, saving energy and reactor size. Removing precursors of such by-products at an earlier, lower temperature stage results in a more energy-efficient and more cost-effective process.

[0114] Alternatively, a selection can be made of hydrochloric acid-containing, intermediate aqueous product solutions that include both the first hydrolysis product solution and the second hydrolysis product solution to fine-tune the composition of products (such as 5-(chloromethyl)furfural) and by-products (such as furfural) to meet market demand.

[0115] Preferably, part or all of the intermediate aqueous solution, suitably containing both hydrochloric acid and saccharides, is directly transferred and / or applied to step (c). If so desired, small amounts of water or hydrochloric acid may be added or removed to obtain an optimal hydrochloric acid concentration and / or an optimal sugar concentration as step (c).

[0116] By transferring the intermediate aqueous solution, suitably containing both hydrochloric acid and saccharides, directly to step (c) without separating the hydrochloric acid from the saccharides, the costly and cumbersome process step of isolating the monosaccharides by first removing such hydrochloric acid is no longer necessary and can be avoided. Separating the hydrochloric acid from the CMF and / or CMF derivatives after step (c) by extraction instead of distillation is advantageous both from an economic as well as a safety standpoint.

[0117] Step (c) suitably comprises heating at least a portion of the hydrochloric acid-containing, aqueous intermediate product solution to a temperature of at least 60° C., preferably at least 70° C. Such heating suitably provides a product solution containing 5-(chloromethyl)furfural. The 5-(chloromethyl)furfural is suitably extracted from such product solution into the extraction solvent. Step (c) thus suitably provides an extraction solvent containing 5-(chloromethyl)furfural.

[0118] Without wishing to be bound by any type of theory, it is believed that the heating in step (c) results in the dehydration of at least a portion of the saccharides present in the aqueous intermediate product solution, suitably containing hydrochloric acid, to 5-(chloromethyl)furfural.

[0119] Step (c) may or may not be carried out in the presence of a chloride-containing promoter, such as lithium chloride, which may advantageously enhance the conversion of saccharides in the aqueous intermediate product solution.

[0120] Furthermore, the hydrochloric acid concentration may be adjusted: additional hydrochloric acid may or may not be added; or additional water may or may not be added or removed. The latter may help to obtain an optimal hydrochloric acid concentration for step (c).

[0121] Preferably, step (c) comprises heating at least a portion of the hydrochloric acid-containing, intermediate aqueous product solution to a temperature of at least 60°C, more preferably at least 70°C, to give a product solution containing 5-(chloromethyl)furfural, while simultaneously extracting 5-(chloromethyl)furfural from such product solution into an extraction solvent. Suitably, some or all of the 5-(chloromethyl)furfural formed may be extracted simultaneously and / or simultaneously from the product solution into an extraction solvent. Preferably, at least a portion of the 5-(chloromethyl)furfural is removed continuously or semi-continuously by in situ liquid-liquid extraction into such extraction solvent.

[0122] Preferably, step (c) is carried out in the presence of such an extracting solvent. More preferably, step (c) comprises heating at least a portion of the hydrochloric acid-containing, intermediate aqueous solution in the presence of an extracting solvent to a temperature of 60° C. or higher, more preferably 70° C. or higher, thereby producing 5-(chloromethyl)furfural, and preferably extracting at least a portion of the produced 5-(chloromethyl)furfural in situ into such an extracting solvent, thereby producing an extracting solvent containing 5-(chloromethyl)furfural.

[0123] After the conversion of the aqueous intermediate solution, or more precisely of the saccharides in the aqueous intermediate solution, and the extraction of 5-(chloromethyl)furfural from the aqueous intermediate solution containing hydrochloric acid, the 5-(chloromethyl)furfural can be suitably exhausted from such solution. Suitably, only a residual aqueous solution containing hydrochloric acid remains. Such a residual aqueous solution containing hydrochloric acid can be advantageously recycled to step (a), optionally after removal of any impurities and / or optionally after reconcentration of hydrochloric acid. That is, preferably, a residual aqueous solution containing hydrochloric acid is obtained, which is recycled to step (a), optionally after adjusting the hydrochloric acid concentration.

[0124] Step (c) of the process according to the invention can be suitably carried out batchwise, semi-continuously or continuously in one or more reactors and / or vessels. These one or more reactors and / or vessels are also referred to herein as dehydration reactors and / or vessels. Preferably, only one reactor is used in step (c). Step (c) can be carried out using countercurrent in an agitated dehydration reactor or a non-agitated reactor, as described in more detail below.

[0125] The reactor may be, for example, a bubble reactor, a plug flow reactor, an external recycle loop reactor or a continuous stirred tank reactor (CSTR). The reactor may be agitated, for example, by stirring or by the use of static mixing.

[0126] After 5-(chloromethyl)furfural is produced, it may be separated from the reaction mixture resulting from step (c) by liquid-liquid extraction, which may suitably be carried out in a separate extraction vessel following the dehydration reactor.

[0127] However, preferably, such liquid-liquid extraction is carried out in situ. By in situ extraction, it is understood herein that 5-(chloromethyl)furfural is extracted into the extraction solvent present in the reaction mixture.

[0128] Therefore, preferably, the reactor of step (c) is further suitable for carrying out liquid-liquid extraction. For example, step (c) may comprise heating at least a portion of the hydrochloric acid-containing, aqueous intermediate product solution together with an extraction solvent in an agitated (e.g., stirred or mixed) reactor to a temperature of 60° C. or higher, more preferably 70° C. or higher, thereby obtaining 5-(chloromethyl)furfural. Subsequently, at least a portion of such 5-(chloromethyl)furfural produced is extracted in situ into the extraction solvent, thereby producing an extraction solvent containing 5-(chloromethyl)furfural. Preferably, such in situ extraction is thus carried out consecutively and / or simultaneously (i.e., in parallel) with the dehydration reaction.

[0129] Advantageously, step (c) is carried out in a continuous stirred tank reactor (CSTR). Suitably, such a CSTR may contain both the aqueous intermediate product solution (at least a portion thereof) as well as the extraction solvent. When applied in a continuous or semi-continuous process, such a CSTR may advantageously be combined with a separate continuous liquid-liquid separator, such as, for example, an in-line liquid-liquid separator using a hydrophobic membrane, a hydrocyclone or a vortex separator.

[0130] However, it may also be advantageous to carry out step (c) in a two-phase co-current or counter-current flow reactor in which a stream of at least a portion of the aqueous intermediate product solution is contacted co-currently or counter-currently, respectively, with a stream of extraction solvent at a temperature of at least 60° C., more preferably at least 70° C.

[0131] Without wishing to be bound by any type of theory, it is believed that 5-(chloromethyl)furfural can be conveniently extracted into the extraction solvent immediately after its preparation by contacting the aqueous intermediate product solution with the extraction solvent in situ, and optionally in countercurrent flow, i.e., when the reaction proceeds in the presence of the extraction solvent, 5-(chloromethyl)furfural can be extracted en masse into the extraction solvent.

[0132] Step (c) is advantageously carried out at a relatively high temperature, i.e. at a temperature of at least 60° C., more preferably at least 70° C., even more preferably at a temperature of at least 80° C. For practical purposes, step (c) may suitably be carried out at a temperature in the range of at least 60° C., more preferably at least 70° C., even more preferably at least 80° C. and at most 120° C., more preferably at most 110° C.

[0133] Step (c) can be carried out over a wide range of pressures, however, preferably step (c) is carried out at a pressure in the range of from 0.1 MPa to 10.0 MPa.

[0134] Preferably, process step (c) continues for a period in the range of at least 0.25 hours, more preferably at least 0.50 hours to at most 10.00 hours, more preferably at most 4.00 hours, and even more preferably at most 2.00 hours.

[0135] The extraction solvent is preferably an organic extraction solvent in which, at the temperature and pressure applied during step (c), 5-(chloromethyl)furfural has a higher solubility than in water.

[0136] The extraction solvent is preferably an organic extraction solvent which has a boiling point, at the pressure applied during step (c), lower than the temperature applied during step (c); and / or an organic extraction solvent which is essentially immiscible with water at the temperature applied during step (c); and / or an organic extraction solvent which is essentially unreactive with hydrochloric acid at the temperature and pressure applied during step (c).

[0137] By organic extractant is herein understood an extractant containing a compound having a hydrocarbon bond. By hydrocarbon bond is herein understood a covalent bond between a hydrogen and a carbon atom. By essentially immiscible with water is herein understood an organic extractant having a solubility of less than 10 grams of water per 100 grams of water.

[0138] The extraction solvent may be, for example, a non-polar solvent or an aprotic polar solvent. Preferably, the extraction solvent is an organic extraction solvent, more preferably selected from the group consisting of C6-C10 aromatic hydrocarbons, C1-C10 chlorinated hydrocarbons and C3-C10 ketones, and mixtures of two or more thereof. By Cx compounds, it is understood herein that compounds contain "x" carbon atoms. By Cx-Cz compounds, it is understood herein that compounds contain carbon atoms ranging from "x" to "z". Suitably, the extraction solvent may be selected from the group consisting of diethyl ether, diisopropyl ether, ethyl acetate, pentane, hexane, heptane, octane, decane, dodecane, cyclohexane, benzene, toluene, xylene, chloroform, dichloromethane, dichloroethane, carbon tetrachloride, trichloromethane (chloroform), methyl tert-butyl ether, and mixtures of two or more thereof. Most preferably, an aromatic extraction solvent is used, more preferably selected from the group consisting of benzene, toluene and xylene.

[0139] When the heating in step (c) is carried out in the presence of an extraction solvent and the 5-(chloromethyl)furfural is suitably extracted in situ with such an extraction solvent, an extraction solvent having a boiling point above 70° C. at the applied pressure is preferred.

[0140] Therefore, more preferably, the extraction solvent is selected from the group consisting of heptane, octane, decane, dodecane, toluene, xylene, 1,2-dichloroethane, carbon tetrachloride and mixtures of two or more thereof.

[0141] Most preferably, the extraction solvent is toluene or 1,2-dichloroethane.

[0142] Preferably, the volume ratio between the hydrochloric acid-containing, aqueous intermediate product solution and the extraction solvent is in the range of 10:1 to 1:10, more preferably in the range of 5:1 to 1:5.

[0143] Preferably, the extraction solvent is either higher or lower in density than water, which allows it to be easily separated from the water by a simple two-phase separation, and preferably allows for proper operation of two-phase countercurrent or cocurrent, two-phase continuous flow reactors.

[0144] The resulting extraction solvent containing 5-(chloromethyl)furfural can then be separated from the aqueous intermediate product solution and / or reaction mixture.

[0145] Such separation may therefore be accomplished in any manner known to be suitable by those skilled in the art, which may or may not include cooling, phase separation, membrane separation, sedimentation and / or centrifugation.

[0146] The extraction solvent containing the separated 5-(chloromethyl)furfural may optionally be dried to remove residual water.

[0147] To remove residual 5-(chloromethyl)furfural from the remaining aqueous intermediate product solution and / or reaction mixture, the remaining aqueous intermediate product solution and / or reaction mixture can optionally be mixed and / or washed with additional extraction solvent to extract such residual 5-(chloromethyl)furfural.

[0148] Preferably, step (c) is carried out in a two-phase countercurrent flow reactor, in which at least a partial flow of the aqueous intermediate product solution containing hydrochloric acid is contacted countercurrently with a flow of the extraction solvent. When a two-phase countercurrent flow reactor is used in which at least a partial flow of the aqueous intermediate product solution is contacted countercurrently with a flow of the extraction solvent, the extraction solvent containing 5-(chloromethyl)furfural is already separated from the aqueous intermediate product solution and / or the reaction mixture in the reactor.

[0149] The 5-(chloromethyl)furfural may or may not be isolated from the extraction solvent containing the 5-(chloromethyl)furfural.

[0150] Preferably, the method further comprises the steps of: (i) isolating or separating 5-(chloromethyl)furfural from the extraction solvent and converting the isolated or separated 5-(chloromethyl)furfural to 2,5 di-formylfuran, 5-(hydroxymethyl)furfural and / or 5-(alkoxymethyl)furfural; or (ii) recovering the extraction solvent containing 5-(chloromethyl)furfural, suitably in its entirety, and converting the 5-(chloromethyl)furfural in the presence of the extraction solvent to 2,5 di-formylfuran, 5-(hydroxymethyl)furfural and / or 5-(alkoxymethyl)furfural.

[0151] Preferably, the 5-(chloromethyl)furfural is further processed in non-isolated form in combination with the extraction solvent, i.e., preferably, the extraction solvent containing the 5-(chloromethyl)furfural is further processed in its entirety.

[0152] Alternatively, the 5-(chloromethyl)furfural is first isolated from the extraction solvent prior to further processing of such 5-(chloromethyl)furfural.

[0153] 5-(chloromethyl)furfural can be isolated from the extraction solvent in any manner known to those skilled in the art, for example, by evaporation and / or distillation. After removal of 5-(chloromethyl)furfural, the extraction solvent may be recycled for reuse. The isolated 5-(chloromethyl)furfural may be converted to 5-(alkoxymethyl)furfural, such as, for example, 2,5 di-formylfuran (DFF), 5-(hydroxymethyl)furfural (HMF) and / or 5-(methoxymethyl)furfural (MMF) or 5-(ethoxymethyl)furfural (EMF), using conventional techniques known in the art.

[0154] As indicated, advantageously, it is not necessary to immediately isolate the 5-(chloromethyl)furfural from the extraction solvent. The extraction solvent containing the resulting 5-(chloromethyl)furfural may be suitably further processed without isolating the 5-(chloromethyl)furfural.

[0155] For example, the extraction solvent can advantageously be used as a solvent in the following process: - reacting 5-(chloromethyl)furfural with an alkanol to form a 5-(alkoxymethyl)furfural ether; - reacting 5-(chloromethyl)furfural with water to produce 5-(hydroxymethyl)furfural; or - 5-(chloromethyl)furfural is converted to 2,5 di-formylfuran. When 5-(chloromethyl)furfural is reacted with an alkanol, such alkanol is preferably selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, isobutanol and tert-butanol.

[0156] Thus, the present invention also provides a method for the production of 5-(alkoxymethyl)furfural, comprising the steps of: 1) The following steps: a) (i) hydrolyzing at least a portion of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution at a temperature of 30° C. or less, the first aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 15.0% to less than 40.0% by weight based on the weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution, to provide a first aqueous hydrolysis product solution containing the remaining solid material and hydrochloric acid; (ii) hydrolyzing at least a portion of the cellulose of the remaining solid material with a second aqueous hydrochloric acid solution at a temperature of 30° C. or less, the second aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 40.0% to 51.0% by weight based on the weight of water and hydrochloric acid in the second aqueous hydrochloric acid solution, to provide a residue and a hydrochloric acid-containing, second aqueous hydrolysis product solution. converting a solid material comprising hemicellulose, cellulose and lignin by (b) - a part or the whole of the hydrochloric acid-containing first aqueous hydrolysis product solution of step (a); and / or - a part or the whole of the hydrochloric acid-containing second aqueous hydrolysis product solution of step (a) transferring a hydrochloric acid-containing, intermediate product aqueous solution comprising: (c) heating at least a portion of the hydrochloric acid-containing, intermediate aqueous product solution to a temperature of at least 60° C. to provide a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from such product solution into an extraction solvent. and 2) recovering the extraction solvent containing 5-(chloromethyl)furfural; and 3) reacting 5-(chloromethyl)furfural with an alkanol, preferably selected from the group consisting of ethanol, propanol, isopropanol, butanol, isobutanol and tert-butanol, in the presence of an extraction solvent at a temperature preferably in the range of from 10° C. to 90° C., more preferably below 50° C., to suitably give 5-(alkoxymethyl)furfural. The method further comprises:

[0157] The step of recovering the extraction solvent containing 5-(chloromethyl)furfural can be optionally combined with step (c), for example when using a two-phase, co-current or counter-current flow reactor. Further preferences for carrying out the reaction of 5-(chloromethyl)furfural can be found, for example, in Estonian Patent Application Publication No. 2013 / 0003. Most preferably, the alkanol is ethanol, which allows the process to produce 5-(ethoxymethyl)furfural (EMF). Further preferences for steps (a), (b) and (c) are as described herein above.

[0158] Additionally, the present invention also provides a method for the production of 5-(methoxymethyl)furfural, comprising the steps of: 1) The following steps: a) (i) hydrolyzing at least a portion of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution at a temperature of 30° C. or less, the first aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 15.0% to less than 40.0% by weight based on the weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution, to provide a first aqueous hydrolysis product solution containing the remaining solid material and hydrochloric acid; (ii) hydrolyzing at least a portion of the cellulose of the remaining solid material with a second aqueous hydrochloric acid solution at a temperature of 30° C. or less, the second aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 40.0% to 51.0% by weight based on the weight of water and hydrochloric acid in the second aqueous hydrochloric acid solution, to provide a residue and a hydrochloric acid-containing, second aqueous hydrolysis product solution. Transforming a solid material comprising hemicellulose, cellulose and lignin by: (b) - a part or the whole of the hydrochloric acid-containing first aqueous hydrolysis product solution of step (a); and / or - a part or the whole of the hydrochloric acid-containing second aqueous hydrolysis product solution of step (a) transferring the aqueous intermediate product solution containing hydrochloric acid to step (c); and (c) heating at least a portion of the hydrochloric acid-containing, intermediate aqueous product solution to a temperature of at least 60° C. to provide a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from such product solution into an extraction solvent. and 2) recovering the extraction solvent containing 5-(chloromethyl)furfural; and 3) reacting 5-(chloromethyl)furfural with methanol in the presence of an extraction solvent at a temperature preferably in the range of from 10° C. to 90° C., more preferably 50° C. or less, to suitably give 5-(methoxymethyl)furfural. The method further comprises:

[0159] The step of recovering the extraction solvent containing 5-(chloromethyl)furfural can optionally be combined with step (c), for example when using a two-phase, co-current or counter-current flow reactor. Further preferences for carrying out the reaction of 5-(chloromethyl)furfural can be found, for example, in Estonian Patent Application Publication No. 2013 / 0003. Further preferences for steps (a), (b) and (c) are as described herein above.

[0160] Still further, the present invention also provides a method for the production of 5-(hydroxymethyl)furfural, comprising the steps of: 1) The following steps: a) (i) hydrolyzing at least a portion of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution at a temperature of 30° C. or less, the first aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 15.0% to less than 40.0% by weight based on the weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution, to provide a first aqueous hydrolysis product solution containing the remaining solid material and hydrochloric acid; (ii) hydrolyzing at least a portion of the cellulose of the remaining solid material with a second aqueous hydrochloric acid solution at a temperature of 30° C. or less, the second aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 40.0% to 51.0% by weight based on the weight of water and hydrochloric acid in the second aqueous hydrochloric acid solution, to provide a residue and a hydrochloric acid-containing, second aqueous hydrolysis product solution. Transforming a solid material comprising hemicellulose, cellulose and lignin by: (b) a part or all of the hydrochloric acid-containing, first aqueous hydrolysis product solution of step (a); and / or a part or all of the hydrochloric acid-containing, second aqueous hydrolysis product solution of step (a). transferring the aqueous intermediate product solution containing hydrochloric acid to step (c); and (c) heating at least a portion of the hydrochloric acid-containing, intermediate aqueous product solution to a temperature of at least 60° C. to provide a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from such product solution into an extraction solvent. and 2) recovering the extraction solvent containing 5-(chloromethyl)furfural; and 3) reacting 5-(chloromethyl)furfural with water in the presence of an extraction solvent at a temperature preferably in the range of from 10° C. to 90° C., more preferably 50° C. or less, to suitably give 5-(hydroxymethyl)furfural. The method further comprises:

[0161] The step of recovering the extraction solvent containing 5-(chloromethyl)furfural can optionally be combined with step (c), for example when using a two-phase, co-current or counter-current flow reactor. Further preferences for steps (a), (b) and (c) are as described herein above.

[0162] Still further, the present invention also provides a process for the production of 2,5 di-formylfuran, comprising the steps of: 1) The following steps: a) (i) hydrolyzing at least a portion of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution at a temperature of 30° C. or less, the first aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 15.0% to less than 40.0% by weight based on the weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution, to provide a first aqueous hydrolysis product solution containing the remaining solid material and hydrochloric acid; (ii) hydrolyzing at least a portion of the cellulose of the remaining solid material with a second aqueous hydrochloric acid solution at a temperature of 30° C. or less, the second aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 40.0% to 51.0% by weight based on the weight of water and hydrochloric acid in the second aqueous hydrochloric acid solution, to provide a residue and a hydrochloric acid-containing, second aqueous hydrolysis product solution. Transforming a solid material comprising hemicellulose, cellulose and lignin by: (b) - a part or the whole of the hydrochloric acid-containing first aqueous hydrolysis product solution of step (a); and / or - a part or the whole of the hydrochloric acid-containing second aqueous hydrolysis product solution of step (a) transferring the aqueous intermediate product solution containing hydrochloric acid to step (c); and (c) heating at least a portion of the hydrochloric acid-containing, intermediate aqueous product solution to a temperature of at least 60° C. to provide a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from such product solution into an extraction solvent. and 2) recovering the extraction solvent containing 5-(chloromethyl)furfural; and 3) oxidizing 5-(chloromethyl)furfural to 2,5 di-formylfuran in the presence of an extraction solvent; The method further comprises:

[0163] The step of recovering the extraction solvent containing 5-(chloromethyl)furfural can optionally be combined with step (c), for example when using a two-phase, co-current or counter-current flow reactor. Further preferences for steps (a), (b) and (c) are as described herein above.

[0164] The above process advantageously makes it possible to heat the saccharides obtained from hemicellulose and / or cellulose and convert them into useful products without the energy waste of heating the lignin. Moreover, the above process advantageously makes it possible to avoid the cumbersome and expensive step of isolating 5-(chloromethyl)furfural from the extraction solvent.

[0165] When producing 5-(alkoxymethyl)furfural, 5-(hydroxymethyl)furfural, and / or diformylfurfural from 5-(chloromethyl)furfural, hydrochloric acid is suitably produced again as a by-product. Such hydrochloric acid may advantageously be recycled directly to step (a) for use. More advantageously, such hydrochloric acid can be added as supplemental hydrochloric acid to the remaining aqueous hydrochloric acid solution recycled from step (c) to step (a). Such recycling of hydrochloric acid and the remaining aqueous hydrochloric acid solution reduces the generation of chlorine-containing waste liquid, contributing to the economy, efficiency and sustainability of the process of the present invention.

[0166] The following non-limiting figures 1 and 2 illustrate examples of methods according to the invention.

[0167] Figure 1 shows a process according to the invention in which step (a) is carried out as a two-stage process including both a pre-hydrolysis stage as well as a main hydrolysis stage. Step (c) of the illustrated process is carried out continuously in a countercurrent two-phase continuous flow reactor in the presence of an extraction solvent.

[0168] Step (a) of the illustrated process is carried out in a reactor series of six hydrolysis reactors (R1-R6). The hydrolysis reactors are operated at a temperature of 20° C. and a pressure of 0.1 megapascals. The process is operated in a series of cycles, each cycle being carried out within a cycle period of 8 hours.

[0169] Figure 1 illustrates the start of a new cycle. At the start of the new cycle, dry wood chips (101) have just been charged into reactor (R1) via solids inlet line (102). Reactor (R2) contains a (partially pre-hydrolyzed) solid material comprising cellulose and lignin, where the hemicellulose fraction has already been partially hydrolyzed.

[0170] Reactor (R3) contains the remaining solid material, mainly containing cellulose and lignin, which have already been completely prehydrolyzed. The solid materials of reactors (R4) and (R5) are completely prehydrolyzed solid materials, the cellulose having already been partially hydrolyzed in the main hydrolysis stage. In the solid material of reactor (R6), the cellulose fraction has been completely hydrolyzed and represents the residue.

[0171] In FIG. 1, reactors (R1) and (R2) represent prehydrolysis stages, while reactors (R3), (R4) and (R5) represent further main hydrolysis stages, and reactor (R6) represents the residue removal stage.

[0172] The dry wood chips (101) in the reactor (R1) are flooded with a plug (105c) of intermediate pre-hydrolysate solution coming from reservoir (103). This plug (105c) of intermediate pre-hydrolysate solution contains an aqueous hydrochloric acid solution which has taken up saccharides during the previous cycle period of the process.

[0173] In the first part of the new cycle, a plug (105a) of fresh first aqueous hydrochloric acid solution, having a hydrochloric acid concentration of 37.0% by weight and essentially still free of saccharides, is introduced into the reactor (R2), thereby pushing a plug (105b) of intermediate pre-hydrolysate solution, which also contains aqueous hydrochloric acid but already contains saccharides (i.e. originating from the hemicellulose fraction of the solid material present in the reactor (R2)), from the reactor (R2) to the reactor (R1). The plug (105b) of intermediate pre-hydrolysate solution pushes a plug (105d) out of the reactor (R1). The plug (105d) previously containing the intermediate pre-hydrolysate solution, however, has now taken up sufficient saccharides to become the final first hydrolysis product solution. Such a final first hydrolysis product solution can be suitably transferred to one or more subsequent steps or devices.

[0174] During the same first part of the cycle, a plug (106a) of a fresh second aqueous hydrochloric acid solution, having a hydrochloric acid concentration of 42.0% by weight and essentially not yet containing saccharides, is introduced into the reactor (R5), thereby pushing a plug (106b) of an intermediate hydrolysate solution containing aqueous hydrochloric acid but also already containing saccharides (i.e. originating from the cellulose fraction of the solid material present in the reactor (R5)) from the reactor (R5) to the reactor (R4). This plug (106b) then pushes a second plug (106c) of an intermediate hydrolysate solution not only containing aqueous hydrochloric acid but also containing saccharides (i.e. originating from the cellulose fraction of the solid material present in the previous reactors (R4) and (R5)) from the reactor (R4) to the reactor (R3). The plug (106c) pushes the final hydrochloric acid-containing, second aqueous hydrolysis product plug (106d) from the reactor (R3). While being forced from reactor (R5) to reactor (R4) and then to reactor (R3), the intermediate hydrolysate solution absorbs more and more saccharides from the solid material remaining in these reactors from the previous stages. The saccharide concentration of the intermediate hydrolysate solution advantageously increases, which makes it possible to obtain higher saccharide concentrations than those obtained in batch operations.

[0175] The final hydrochloric acid-containing, second aqueous hydrolysis product plug (106d) extruded from reactor (R3) is conveniently transferred via liquid outlet line (112) to a countercurrent two-phase continuous flow reactor (114).

[0176] During this same part of the cycle, the lignin-containing residue (107) may be suitably removed from the reactor (R6) via the solids outlet line (108).

[0177] In a second part of the cycle (not illustrated), the intermediate hydrolysate solution is withdrawn from the reactor (R5) and forced into the reactor (R4), and the intermediate hydrolysate solution is separated from the residue, which remains in the reactor (R5). The plug of withdrawn intermediate hydrolysate solution withdrawn from the reactor (R5) and forced into the reactor (R4) pushes the plugs of the reactors (R4) and (R3). The plug of intermediate hydrolysate solution present in the reactor (R3) is pushed from the reactor (R3) into the reactor (R2). The plug of intermediate pre-hydrolysate solution present in the reactor (R2) is pushed from the reactor (R2) into the reactor (R1). The plug (105e) of intermediate pre-hydrolysate solution present in the reactor (R1) is pushed from the reactor (R1) into the storage tank (103). At the same time, the reactor (R6) can be charged with a new batch of dried wood chips. The cycle is now complete and all reactors have moved one position in the reactor series: reactor (R6) has moved to the position of reactor (R1); reactor (R1) has moved to the position of reactor (R2); reactor (R2) has moved to the position of reactor (R3); reactor (R3) has moved to the position of reactor (R4); reactor (R4) has moved to the position of reactor (R5) and reactor (R5) has moved to the position of reactor (R6).

[0178] The situation where all the reactors have shifted one position is illustrated in FIG. 2. FIG. 2 illustrates the start of the subsequent cycle at time "t+8 hours". The dry wood chips in the reactor (R6) can be flooded with a plug (204c) of intermediate pre-hydrolysate solution drawn from the reservoir (103). This is the same intermediate pre-hydrolysate solution that was stored in such reservoir (103) in the second part of the previous cycle. The subsequent cycle can be carried out in a similar manner as described above for the preceding cycle, with the numbers (201), (202), (205a-e) and (206a-d) referring to features similar to those referred to by the numbers (101), (102), (105a-e) and (106a-d) in FIG. 1. After a total of 6 cycles and a period of 48 hours, the situation is again exactly as in FIG. 1.

[0179] It is noted that in the above examples, all pre-hydrolysates and hydrolysate solutions are suitably aqueous hydrolysates and aqueous pre-hydrolysates solutions, respectively.

[0180] In the above, all hydrochloric acid concentrations are based on mass relative to the total mass of water and hydrochloric acid.

[0181] As described above, the final hydrochloric acid-containing, second aqueous hydrolysate solution, (106d), (206d), respectively, is pumped from reactor (R3) and transferred via liquid outlet line (112) to a countercurrent two-phase continuous flow reactor (114). In such countercurrent two-phase continuous flow reactor, the hydrochloric acid-containing, aqueous hydrolysate solution is subsequently contacted with an extraction solvent, such as toluene, provided via liquid inlet line (116). The countercurrent two-phase continuous flow reactor (114) is operated at 90°C.

[0182] A stream of extraction solvent (120) containing 5-(chloromethyl)furfural is obtained from the top of the countercurrent two-phase continuous flow reactor (114) via liquid outlet line (130), and a stream containing the remaining aqueous hydrochloric acid solution (122) is obtained from the bottom of the countercurrent two-phase continuous flow reactor (114) via liquid outlet line (124).

[0183] A bottoms stream (122) containing the remaining aqueous hydrochloric acid-containing solution is optionally recycled via recycle line (126) (shown as a dotted line) to be reused as at least a portion of the first or second hydrochloric acid solutions. If so desired, small amounts of impurities can be removed, and an optional bleed stream (128) can be present (shown as a dotted line).

[0184] The top stream of the reactor (114) of 5-(chloromethyl)furfural-containing extraction solvent (120) is transferred via liquid outlet line (130) to a further reactor (132). In the further reactor (132), the 5-(chloromethyl)furfural is reacted with ethanol provided via liquid inlet line (134) at a temperature of 50° C., thereby producing 5-(ethoxymethyl)furfural and hydrochloric acid by-product. The 5-(ethoxymethyl)furfural is withdrawn from the reactor (132) via liquid outlet line (136) for further processing. The by-product, including hydrogen chloride, can be conveniently recycled via recycle line (138) to be reused as supplemental hydrochloric acid to produce at least a portion of the first or second hydrochloric acid solutions described above. The invention is further illustrated by the following non-limiting examples. EXAMPLES

[0185] Example 1 Hydrolysis of pine wood In the first hydrolysis step (hereafter referred to as the pre-hydrolysis step), about 1150 grams of dry pine wood chips having a particle size of about 4-5 centimeters as determined by visual inspection were divided into five tubular reactors each having a height of about 60 centimeters and a diameter of about 5.3 centimeters. The pine wood contained about 30.6% by weight cellulose, about 13.7% by weight hemicellulose, and about 30.6% by weight lignin, with the remainder being other compounds.

[0186] The pine wood chips were treated with a liquid column of about 8.7 liters of an aqueous solution containing about 37% by weight hydrochloric acid (HCl) in a semi-continuous manner such that the pine wood chips were treated in each reactor for about 16 hours. After treatment, the liquid was separated from the remaining solid material by a glass filter plate pore size class 0 (i.e., having a nominal pore size of 160-250 μm), resulting in about 5.9 liters of hydrochloric acid-containing, first aqueous hydrolysis product solution (hereafter referred to as the pre-hydrolysis product).

[0187] The remaining solid material was treated with a liquid column of about 5.1 liters of an aqueous solution containing about 42% by weight hydrochloric acid (HCl) in a semi-continuous manner such that the remaining solid material in each reactor was treated for about 24 hours. After treatment, the liquid was separated from the remaining solid material by a glass filter plate pore size class 0 (i.e., having a nominal pore size of 160-250 μm), resulting in about 4.9 liters of hydrochloric acid-containing, second hydrolysis product aqueous solution (hereafter referred to as the main hydrolysis product).

[0188] The composition of the prehydrolysis product and the main hydrolysis product was determined by ion exchange chromatography. Of each of the prehydrolysis product and the main hydrolysis product, two samples were taken and the contents (weight percent (wt%) of the different sugar components) were determined. Table 1 below lists the average of the two measurements. Both the main hydrolysis product and the prehydrolysis product were essentially free of lignin.

[0189] [Table 1]

[0190] Example 2 Conversion of prehydrolysis products A sample of 0.5 ml of the prehydrolysis product obtained in Example 1 was combined with 1 ml of toluene and charged into an 8 ml reactor using magnetic stirring at 1600 revolutions per minute (rpm). The reaction mixture was heated to 100° C. for 1 hour. The reaction was then quenched by placing the reactor in ice and separated into a toluene layer and an aqueous layer. The aqueous layer was washed twice with 0.5 ml of fresh toluene. The toluene layers were then combined and analyzed by gas chromatography (GC) using dioxane as an internal standard to determine the yield of furfural and 5-(chloromethyl)furfural (CMF). The aqueous layer was analyzed for residual sugars by ion exchange chromatography and high performance liquid chromatography (HPLC). The aqueous phase further contained levulinic acid as determined by HPLC.

[0191] The yields of furfural and CMF in weight percent (wt%) were determined relative to the total weight of sugars in the 0.5 ml sample and are summarized in Table 2 below.

[0192] Example 3 Conversion of main hydrolysis products A 0.5 ml sample of the main hydrolysis product obtained in Example 1 was combined with 1 ml toluene and charged into an 8 ml reactor using magnetic stirring at 1600 revolutions per minute (rpm). The reaction mixture was heated to 100° C. for 1 hour in the same manner as in Example 2. The reaction was then quenched by placing the reactor in ice and separated into a toluene layer and an aqueous layer. The aqueous layer was washed twice with 0.5 ml fresh toluene. The toluene layers were then combined and analyzed by gas chromatography (GC) using dioxane as an internal standard to determine the yields of furfural and 5-(chloromethyl)furfural (CMF). The aqueous layer was analyzed for residual sugars by ion exchange chromatography and HPLC.

[0193] The yields of furfural and CMF in weight percent (wt%) were determined relative to the total weight of sugars in the 0.5 ml sample and are summarized in Table 2 below.

[0194] [Table 2]

[0195] The process according to the invention allows for the flexibility of co-production of furfural and CMF depending on the market demand for each of these products, as shown in Table 2. The flexibility to modify the co-production of furfural and CMF can be achieved by including some or all of the pre-hydrolysis product and / or some or all of the main hydrolysis product in the process at elevated temperature (100° C. as illustrated in this example) and extracting the products into an extraction solvent (toluene as illustrated in this example).

[0196] The above also illustrates that advantageously, in step (c) only the main hydrolysis product can be used, making it possible to use at least a portion of the pre-hydrolysis product to produce other valuable products such as xylitol from xylose, thus making more efficient use of wood saccharides.

[0197] (Examples 4 to 9) Conversion of 5-chloromethylfurfural The amount of 5-chloromethylfurfural (CMF) as listed in Table 3 was weighed into a 1.8 mL HPLC vial and dissolved in the amount of dichloromethane (DCM) solvent as listed in Table 3. To this solution of CMF in dichloromethane solvent, the amount of methanol (MeOH) as listed in Table 3 was added. Immediately after adding methanol to the reaction mixture, the vial was heated to a temperature (T) as listed in Table 3 to start the reaction. After the reaction time (t) listed in Table 3, the vial was immediately cooled in an ice bath and subsequently worked up for analysis (gas chromatography and ultra-performance liquid chromatography). Table 3 provides a summary of the conversion to 5-chloromethylfurfural (CMF) and the yield and selectivity of 5-(methoxymethyl)furfural (MMF).

[0198] [Table 3]

Claims

1. The process is as follows: a) (i) hydrolyzing at least a portion of the hemicellulose of the solid material with a first aqueous hydrochloric acid solution at a temperature of 40° C. or less, the first aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 15.0% to less than 40.0% by weight based on the weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution, to provide a first aqueous hydrolysis product solution containing the remaining solid material and hydrochloric acid; (ii) hydrolyzing at least a portion of the cellulose of the remaining solid material with a second aqueous hydrochloric acid solution at a temperature of 40° C. or less, the second aqueous hydrochloric acid solution having a hydrochloric acid concentration in the range of 40.0% to 51.0% by weight based on the weight of water and hydrochloric acid in such second aqueous hydrochloric acid solution, to provide a residue and a hydrochloric acid-containing, second aqueous hydrolysis product solution. converting a solid material comprising hemicellulose, cellulose and lignin by (b) - a part or the whole of the hydrochloric acid-containing first aqueous hydrolysis product solution of step (a); and / or - a part or the whole of the hydrochloric acid-containing second aqueous hydrolysis product solution of step (a) transferring the aqueous intermediate product solution containing hydrochloric acid to step (c); and (c) heating at least a portion of the hydrochloric acid-containing, intermediate aqueous product solution to a temperature of at least 60° C. to provide a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from such product solution into an extraction solvent. The method includes:

2. 10. The process of claim 1, wherein step (a) is carried out in a plurality of reactors connected in series, ranging from 2 or more to 16 or less reactors.

3. Step (a) is carried out in multiple reactors; one or more portions of the first aqueous hydrochloric acid solution are transferred from one reactor to another reactor and contact immobile solid materials present in such reactors; and / or 3. The process of claim 1 or 2, wherein one or more portions of the second aqueous hydrochloric acid solution are transferred from one reactor to another and contact any remaining fixed solid material present in such reactors.

4. the first aqueous hydrochloric acid solution is contacted countercurrently with the solid material; and / or 4. The method of claim 1, wherein the second aqueous hydrochloric acid solution is contacted countercurrently with the remaining solid material.

5. 5. The method of claim 1, wherein in step (i) one or more portions of the first aqueous hydrochloric acid solution, optionally in combination with other fluids, form a plug or liquid column, which plug or liquid column moves through a plurality of reactors, each reactor containing an amount of fixed solid material.

6. 6. The process according to any one of claims 1 to 5, wherein in step (ii) one or more portions of the second aqueous hydrochloric acid solution, optionally in combination with other fluids, form a plug or liquid column, which plug or liquid column moves through a plurality of reactors, each reactor containing an amount of fixed remaining solid material.

7. 7. The method according to claim 1, wherein in step (c), some or all of the 5-(chloromethyl)furfural is simultaneously extracted from the product solution into the extraction solvent.

8. 8. The process according to claim 1, wherein step (c) is carried out in a two-phase countercurrent flow reactor, in which a stream of at least a portion of the aqueous intermediate product solution containing hydrochloric acid is contacted countercurrently with a stream of the extraction solvent.

9. 9. The method according to any one of claims 1 to 8, wherein the extraction solvent comprises toluene and / or 1,2-dichloroethane.

10. 10. The method according to any one of claims 1 to 9, wherein step (c) is carried out at a temperature of 70°C or higher.

11. 11. The method of claim 1, further comprising separating the 5-(chloromethyl)furfural from the extraction solvent.

12. (i) isolating 5-(chloromethyl)furfural from the extraction solvent and converting the isolated 5-(chloromethyl)furfural to 2,5 di-formylfuran, 5-(hydroxymethyl)furfural and / or 5-(alkoxymethyl)furfural; or (ii) recovering the extraction solvent containing 5-(chloromethyl)furfural and converting the 5-(chloromethyl)furfural in the presence of the extraction solvent into 2,5 di-formylfuran, 5-(hydroxymethyl)furfural and / or 5-(alkoxymethyl)furfural.

12. The method of claim 1, further comprising:

13. - recovering the extraction solvent containing 5-(chloromethyl)furfural; and - reacting 5-(chloromethyl)furfural with an alkanol selected from the group consisting of ethanol, propanol, isopropanol, butanol, isobutanol and tert-butanol in the presence of an extraction solvent at a temperature ranging from 10°C to 90°C to obtain 5-(alkoxymethyl)furfural.

12. The method of any one of claims 1 to 11, comprising:

14. - recovering the extraction solvent containing 5-(chloromethyl)furfural; and - reacting 5-(chloromethyl)furfural with methanol in the presence of an extraction solvent at a temperature ranging from 10°C to 90°C to give 5-(methoxymethyl)furfural.

12. The method of claim 1, further comprising:

15. - recovering the extraction solvent containing 5-(chloromethyl)furfural; and - reacting 5-(chloromethyl)furfural with water in the presence of an extraction solvent at a temperature ranging from 10°C to 90°C to give 5-(hydroxymethyl)furfural.

12. The method of claim 1, further comprising:

16. - recovering the extraction solvent containing 5-(chloromethyl)furfural; and - oxidizing 5-(chloromethyl)furfural to 2,5 di-formylfuran in the presence of an extracting solvent; 12. The method of claim 1, further comprising:

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