Method for converting solid lignocellulosic materials

Abstract

1. A method for converting solid lignocellulosic material containing hemicellulose, cellulose, and lignin, comprising the steps of: (a) hydrolyzing at least a portion of the hemicellulose and at least a portion of the cellulose of the solid lignocellulosic material with an aqueous hydrochloric acid solution at a temperature of 40°C or less, preferably 30°C or less, wherein the aqueous hydrochloric acid solution contains hydrochloric acid in an amount of 40.0 mass% or more and 51.0 mass% or less, based on the total mass of water and hydrochloric acid contained therein, to obtain a hydrochloric acid-containing aqueous hydrolysate solution; (b) separating the hydrochloric acid-containing aqueous hydrolysate solution from the lignin; and (c) heating at least a portion of the hydrochloric acid-containing aqueous hydrolyzate solution to a temperature of 60°C or higher to obtain a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent; A method comprising:

Description

[Technical field]

[0001] 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 CO2 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 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 known as 2,5-furandicarbaldehyde.

[0004] 2,5-di-formylfuran can function as a monomer or crosslinker in the preparation of polymers, but can also be used as a surface treatment agent for certain metals, as a binder, or as a corrosion inhibitor. It can also be used as a precursor to 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, as described, for example, in French Patent Application Publication No. 3008409. Furthermore, the oxidation of 5-chloromethylfurfural to obtain 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] 5-(alkoxymethyl)furfural compounds are of interest in 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, however, is not attractive for the conversion of solid lignocellulosic materials on a commercial scale.

[0009] Solid lignocellulosic materials include not only cellulose, but also hemicellulose and lignin. When contacted with concentrated hydrochloric acid at high temperatures, as in the Mascal process, the hemicellulose and cellulose are converted into various pentoses (C5 sugars) and hexoses (C6 sugars). Under the conditions of the Mascal process, these pentoses and hexoses react with lignin in a variety of reactions resulting in unprofitable by-products and / or contaminants. In commercial-scale processes, these unprofitable by-products must further be repeatedly removed, making the overall process complex, expensive, and economically unattractive.

[0010] The Mascal process has a further disadvantage in that the entire solid lignocellulosic material is heated. Not only are the hemicellulose and cellulose fractions heated, but the lignin fraction is also heated. However, the heated lignin cannot be converted into any useful products. Valuable energy, reactants, and reactor volume are wasted when converting the entire lignocellulosic material in the process described by Mascal.

[0011] The residual lignin produced in the Mascal process also entails problems. 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 favorable for incineration.

[0012] Furthermore, the Mascal process requires comminution of the solid lignocellulosic feedstock and very intensive stirring of the reaction mixture. Reducing the particle size of the solid lignocellulosic feedstock to a powder and intensive stirring of the reaction mixture are relatively easy to handle on a laboratory scale, but can be very difficult and energy intensive when dealing with large amounts of feedstock on an industrial scale.

[0013] 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 the biomass can be pretreated to disrupt the crystalline structure of cellulose and hemicellulose and to degrade lignin structures (if present), thereby helping to make the sugars in the biomass more accessible. Typical pretreatments mentioned include mechanical treatments (e.g., cutting, pulverizing, grinding), concentrated acids, and dilute acids. 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, even in this method, lignin is present as part of the feedstock. Commercialization of this method is accompanied by similar disadvantages and complexities as the Mascal method.

[0014] It would therefore be an advancement in the art to provide a process for the production of 5-(chloromethyl)furfural from solid lignocellulosic materials that does not suffer from the above-mentioned disadvantages and complexities associated with lignin and / or that can be more easily scaled up to commercial scale and / or that provides more efficient conversion to 5-(chloromethyl)furfural. It would be a further advancement if such a process could be operated in a continuous or semi-continuous mode. [Prior art documents] [Patent documents]

[0015] [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 [Non-patent literature]

[0016] [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 Summary of the Invention [Means for solving the problem]

[0017] Such a method has now been obtained by the method according to the invention. The invention therefore relates to a method for the conversion of a solid lignocellulosic material containing hemicellulose, cellulose and lignin, comprising the following steps: (a) hydrolyzing at least a portion of the hemicellulose and at least a portion of the cellulose of the solid lignocellulosic material with an aqueous hydrochloric acid solution at a temperature of 40° C. or less, preferably 30° C. or less, the aqueous hydrochloric acid solution containing hydrochloric acid in an amount ranging from 40.0% by mass to 51.0% by mass based on the total mass of water and hydrochloric acid in the aqueous hydrochloric acid solution, to obtain an aqueous hydrochloric acid-containing hydrolysate solution; (b) separating the hydrochloric acid-containing aqueous hydrolysate solution from the lignin; and (c) heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of 60° C. or higher to obtain a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent; The present invention provides a method comprising:

[0018] Such a method suitably produces a 5-(chloromethyl)furfural-containing extraction solvent.

[0019] In the method according to the present invention, lignin can be easily removed before the production of 5-(chloromethyl)furfural. Moreover, the undesirable impurities associated with lignin can also be removed in this manner. Thus, the disadvantages and complications of the Mascal method and the method described in WO 2014 / 066746 can be avoided.

[0020] The method according to the invention can be readily scaled up to an economically attractive commercial scale process, and may be suitably operated in a continuous or semi-continuous mode, as described in more detail below.

[0021] 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. As a result, the residual lignin recovered from the process according to the invention can be expected to contain less covalently bound chlorine.

[0022] Furthermore, the method according to the invention allows a very economical separation of hydrochloric acid. Hydrochloric acid is a compound that is difficult and expensive to separate from sugars, for example from the sugars in the aqueous hydrolysate solution. By sending the aqueous hydrochloric acid-containing hydrolysate solution directly to step (c) without separating hydrochloric acid, the expensive and difficult process step for removing hydrochloric acid when separating the sugars is no longer necessary and can be avoided. After conversion of at least a part of the sugars in the aqueous hydrolysate solution to 5-(chloromethyl)furfural, such 5-(chloromethyl)furfural can be extracted in an easy and economically attractive manner by extraction as mentioned in step (c). As will be explained in more detail below, the simultaneous 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.

[0023] The 5-(chloromethyl)furfural may or may not be separated from the extraction solvent, and may then be suitably subsequently used in a process for the production of 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), whether in the presence or absence of an extraction solvent.

[0024] The method of the present invention is illustrated by the following diagram: [Brief description of the drawings]

[0025] [Figure 1]FIG. 1 shows a first cycle of the process according to the invention, starting at time "t", in which step (a) is carried out semi-continuously in multiple reactors and step (c) of the process of the invention is carried out continuously in a countercurrent two-phase continuous flow reactor in the presence of an extraction solvent. [Diagram 2] FIG. 2 shows a second cycle in a similar manner to FIG. 1, starting at time "t+8 hours." DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Lignocellulosic materials are understood herein to be materials containing cellulose, hemicellulose, and lignin. Cellulose (also referred to herein as cellulosic materials) is understood herein to be a homopolysaccharide containing glucose-based monomer units, such as cellobiose. Hemicellulose (also referred to herein as hemicellulosic materials) is also a polysaccharide, but is distinct from cellulose. Hemicellulose may, for example, contain pentose monomer units, such as xylose and arabinose, hexose monomer units, such as glucose and mannose, hexuronic acid, and deoxyhexose-based monomer units. Some hemicelluloses may be essentially composed of only one type of monomer unit (e.g., xylan, which contains essentially only xylose), while other hemicelluloses may contain several different types of monomer units (e.g., glucomannan, which contains glucose and mannose).

[0027] The method according to the invention can use a variety of solid lignocellulosic materials as feedstock. Examples of solid lignocellulosic materials that may be suitably used in the method of the invention include agricultural wastes, 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; agricultural and forestry products and / or 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.

[0028] Preferably, the solid lignocellulosic material is inedible, preventing the process from competing with food production. Most preferably, the solid lignocellulosic material comprises or consists of wood. The wood may include softwood and / or hardwood and may originate from any type of tree, such as spruce, pine, willow, larch, oak, birch, poplar, eucalyptus and other trees.

[0029] 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 the glucose-based monomer units.

[0030] Depending on the market demand for a given by-product, some types of wood may be preferred over others. 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 a wood or wood-related material having 10 wt% (weight percent) or more of xylose units based on the total weight of its non-glucose units. Examples of wood types suitable for this purpose include Acer rubrum, Betula alleghaniensis, Betula papyrifera, Betula verrucosa, Fagus grandifolia, Fraxinus excelsior, Populus tremuloides, Robinia pseudoacacia, and Ulmus Americana. The aqueous hydrolysate solution containing hydrochloric acid obtained in step (a) then contains sugars, suitably including xylose. Thus, the process according to the invention advantageously allows for the co-production of furfural.

[0031] In cases where it is desired to maximize the production of 5-(chloromethyl)furfural, lignocellulosic materials containing large amounts of epimers of glucose, such as mannose or galactose, can be used. Examples of wood species suitable for this purpose include balsam fir (Abies balsamea), European larch (Larix decidua), American larch (Larix laricina), Norway spruce (Picea abies), Canadian spruce (Picea glauca), Scots pine (Pinus sylvestris), and Canadian hemlock (Tsugo Canadensis). In such cases, the lignocellulosic material is preferably wood or wood-related material and contains 10% or more by weight of mannose units based on the total weight of non-glucose units in the hemicellulose fraction.

[0032] When it is desired to produce 5-(chloromethyl)furfural and minimize the generation of by-products, lignocellulosic materials containing small amounts of hemicellulose can be used.

[0033] The solid lignocellulosic material may conveniently be washed, dried, fire, roasted and / or particle size reduced prior to use 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.

[0034] Preferably, the solid lignocellulosic material in the process is a solid lignocellulosic material whose particles have a particle size, preferably 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 process is a solid lignocellulosic material whose particles 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.

[0035] 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, e.g., grass, pomace and / or stover, with a desired morphology. Such a morphology can advantageously limit the collapse of material inside the reactor, which may otherwise cause undesirable pressure losses during hydrolysis of hemicellulose and cellulose.

[0036] Prior to step (a), the solid lignocellulosic material may be suitably fed to the reactor in any manner known to those 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 solid lignocellulosic material may be suitably charged to such reactor in a batchwise, semi-continuous, or continuous manner. Preferably, the solid lignocellulosic material may be charged to the reactor through one or more inlets located at the top of such reactor and / or through one or more side inlets located at the reactor wall, preferably in a continuous or semi-continuous manner.

[0037] The solid lignocellulosic material is preferably loaded into a suitably essentially vertical tubular reactor, which may suitably be equipped with an openable discharge opening to allow the discharge of any residual lignin after the process, preferably such a discharge opening is located at the bottom of such a reactor.

[0038] Step (a) preferably comprises hydrolysing at least a portion of the solid lignocellulosic material (i.e. at least a portion of the hemicellulose and at least a portion of the cellulose of the solid lignocellulosic material) at a temperature of 40° C. or less, preferably 30° C. or less. The solid lignocellulosic material is hydrolyzed with an aqueous hydrochloric acid solution, the solution comprising in the range of 40.0% to 51.0% by weight of hydrochloric acid, based on the total weight of water and hydrochloric acid in said aqueous hydrochloric acid solution. Such step (a) preferably produces an aqueous hydrochloric acid-containing hydrolysate solution. The term "hydrolysate" is well known to those skilled in the art to refer to the product of hydrolysis.

[0039] Step (a) is preferably carried out in multiple reactors, preferably reactors connected in series. Such multiple reactors are also referred to herein as a series of reactors. Any reactor used in step (a) is also referred to herein as a hydrolysis reactor.

[0040] Preferably, step (a) is carried out in a plurality of reactors (also called columns) connected in series, as described for the Bergius-Linus process. Examples of Bergius-Linus processes include the Bergius-Linus process, preferably modified by Riehm, as described, for example, in US Pat. No. 2,778,751. It is also possible to carry out step (a) in a plurality of reactors, as described in WO 2012 / 061085.

[0041] Preferably, step (a) is carried out semi-continuously, preferably during one or more continuous cycle periods. A cycle period, as used herein, can be suitably understood as the period during which one cycle is carried out, as illustrated in the examples. Each cycle period preferably lasts in the range of 4 to 24 hours, more preferably in the range of 6 to 12 hours, most preferably in the range of 7 to 9 hours. For example, the cycle period may be 8 hours.

[0042] Preferably, step (a) is carried out in a plurality of reactors, preferably connected in series, where one or more portions of the aqueous hydrochloric acid solution are transferred from one reactor to another and contacted with (portions of) the optionally partially hydrolyzed immobile solid material. These (portions of) the optionally partially hydrolyzed immobile solid lignocellulosic materials can be suitably loaded into the reactors or are otherwise present in the reactors. Since after partial hydrolysis the original solid lignocellulosic material may no longer be complete, such partially hydrolyzed lignocellulosic materials, including partially hydrolyzed hemicellulose and / or partially hydrolyzed cellulose, are also referred to herein simply as partially hydrolyzed "material".

[0043] More preferably, the aqueous hydrochloric acid solution is contacted in countercurrent flow with each of the optionally partially hydrolyzed solid lignocellulosic, hemicellulosic and cellulosic materials.

[0044] Preferably, in step (a), one or more portions of the aqueous hydrochloric acid solution may be suitably combined, optionally with other fluids, to form a plug or liquid column which moves continuously or semi-continuously, preferably in a countercurrent direction, through a plurality of reactors, each reactor containing a quantity of immobile, optionally already partially hydrolyzed material.

[0045] When step (a) is carried out countercurrently, one or more portions of fresh aqueous hydrochloric acid may be suitably fed to a reactor holding already partially hydrolyzed material, sugars may be absorbed from such already partially hydrolyzed material, and one or more portions of aqueous hydrochloric acid (suitably thus containing some sugars) may then pass from the outlet of such reactor to the inlet of a preceding reactor, which holds less or no hydrolyzed material.

[0046] After absorbing the sugars, the aqueous hydrochloric acid solution is no longer fresh and is also referred to herein as an intermediate hydrolysate aqueous solution. Thus, an intermediate hydrolysate aqueous solution containing hydrochloric acid is understood herein as an aqueous hydrochloric acid solution further comprising sugars. Thus, such an intermediate hydrolysate aqueous solution preferably comprises sugars and hydrochloric acid, and preferably has a hydrochloric acid concentration in the range of 40.0% by weight to 51.0% by weight, based on the total weight of water and hydrochloric acid in such a solution. More preferred concentrations are described below for the aqueous hydrochloric acid solution. It is also possible for the intermediate hydrolysate aqueous solution to be slowly further diluted as it moves from one reactor to the next. However, the intermediate hydrolysate aqueous solution may still be preferably used for contacting the optionally partially hydrolyzed material, preferably to absorb further sugars therefrom. During the movement from one reactor to another, preferably in countercurrent, the intermediate hydrolysate aqueous solution may be gradually saturated with sugars until finally a fully saturated aqueous hydrochloric acid-containing hydrolysate solution is obtained, which can be separated in step (b).

[0047] When carried out in countercurrent, step (a) preferably comprises a plurality of “y” reactors R1 to R2 connected in series. y wherein fresh solid lignocellulosic material containing hemicellulose and cellulose is present in or introduced into reactor R1 and each of the subsequent reactors R2 to R y comprises partially hydrolyzed material, where the degree of hydrolysis of the material ranges from R2 to R y , and one or more portions of fresh aqueous hydrochloric acid are added to the last reactor R y is introduced into the reactor R y The aqueous hydrochloric acid solution moves countercurrently from reactor R1 to reactor R2, where a portion of the aqueous hydrochloric acid solution gradually absorbs sugars from the optionally already partially hydrolyzed material, thus producing an aqueous hydrochloric acid-containing hydrolysate solution, which can be removed from reactor R1. Such an aqueous hydrochloric acid-containing hydrolysate solution will advantageously contain more sugars than if step (a) were carried out in a single reactor. Suitably, the aqueous hydrochloric acid solution in reactor R2 is removed from reactor R1. yIn the reactor R, a residue containing lignin (also called "residual lignin") remains. y Preferably, "y" is a number in the range of 2 to 16, inclusive, more preferably 4 to 8, inclusive.

[0048] Thus, preferably, step (a) comprises hydrolyzing the hemicellulose and cellulose of the solid lignocellulosic material using an aqueous hydrochloric acid solution at a temperature of 30° C. or less, the aqueous hydrochloric acid comprising in the range of 40.0% to 51.0% by mass of hydrochloric acid based on the combined mass of water and hydrochloric acid in said aqueous hydrochloric acid solution, wherein the lignocellulosic material is contacted with the aqueous hydrochloric acid solution in a plurality of reactors connected in series in a countercurrent manner to obtain an aqueous hydrochloric acid-containing hydrolysate solution.

[0049] Preferably, step (a) is carried out in a plurality of reactors, preferably 2 or more, more preferably in the range of 2 to 16, even more preferably in the range of 4 to 8, most preferably in the range of 4 to 7 reactors connected in series.

[0050] Step (a) may advantageously be carried out in a continuous or semi-continuous manner. For example, step (a) may be carried out in a continuously repeated cycle. Preferably, in such a continuously repeated cycle: Step (a) is performed by distributing "y" reactors R1 to R y The process is carried out in a series of reactors, where fresh lignocellulosic material is present in reactor R1 and each subsequent reactor R2 to R y contains partially hydrolyzed lignocellulosic material, wherein one or more portions of the fresh aqueous hydrochloric acid are added to the final reactor R y into the reactor R1 and pushes forward a liquid column which contains the front part of the aqueous hydrochloric acid solution. y The reaction is carried out in a countercurrent direction from the reactor R1 to the reactor R2. y the residue present in the reactor R1 and an aqueous hydrolysate solution containing hydrochloric acid are produced, and this aqueous hydrolysate solution containing hydrochloric acid is recovered from the reactor R1; and The residue is then fed to the reactor R y taken from; then Reactors R1 to R y Each of the reactors R2 to R y shifts to the position previously occupied by each of Each reactor R y shifts to the position previously occupied by the respective reactor R1.

[0051] A cycle period is preferably a period during which all of the above described operations are carried out and then each reactor can be shifted one position in the series of reactors. For example, if the process is to cycle "y" reactors R1 to R2, y When carried out with a series of reactors of y, the cycle period may thus preferably be the period between a preceding shift in the series of reactors and a succeeding shift in the series of reactors. Starting at t=0 and using "y" reactors, after "y" cycle periods, the series of reactors preferably again has the same configuration as at t=0.

[0052] The residue may suitably comprise residual lignin.

[0053] The aqueous solution and any intermediate inert fluids used in the cycle may enter the reactor through inlets located at the top of the reactor, at the bottom of the reactor, or in the reactor wall near the top and bottom, respectively, and preferably exit the reactor opposite such inlets.

[0054] Cycle times can vary widely, but are preferably in the range of 4 hours or more, more preferably 6 hours or more to 12 hours or less, more preferably 9 hours or less.

[0055] The reactor in which step (a) can be carried out is also referred to herein as "hydrolysis reactor". Such a hydrolysis reactor is preferably a tubular reactor containing a packed bed of solid lignocellulosic material, such as wood chips. The hydrolysis reactor can, for example, comprise a cylindrical vessel with its axis arranged essentially vertically or essentially horizontally. Preferably, the hydrolysis reactor comprises a cylindrical vessel with its axis arranged essentially vertically. The reactor may be slightly inclined at an angle to allow easier discharge of the residue. Examples of suitable reactors include, for example, the reactors described in U.S. Pat. No. 2,778,751, European Patent No. 1,878,480, WO 2015 / 136044, and unpublished international application PCT / EP2017 / 071914. The aqueous solution containing hydrochloric acid can advantageously flow through such a hydrolysis reactor in a continuous or semi-continuous manner.

[0056] Step (a) is advantageously carried out at a relatively low temperature, i.e. at a temperature below 30° C. For practical purposes, step (a) may suitably be carried out at a temperature in the range of at least 0° C., more preferably at least 5° C., even more preferably at least 10° C. and at most 29° C., more preferably at most 25° C.

[0057] Step (a) can be carried out at a wide range of pressures. Preferably, however, step (a) is carried out at ambient pressure of about 0.1 megapascals (MPa). All pressures referred to herein are absolute pressures.

[0058] Preferably, the aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of 41.0% by mass or more and 45.0% by mass or less, based on the total mass of water and hydrochloric acid in such aqueous hydrochloric acid solution.

[0059] Step (a) suitably results in an aqueous hydrolysate solution containing hydrochloric acid, by which is understood herein a solution comprising the hydrolysis product.

[0060] The aqueous hydrolysate solution may suitably contain sugars and hydrochloric acid.

[0061] The aqueous hydrolysate solution may suitably contain monosaccharides, disaccharides and / or oligosaccharides, where oligosaccharides are understood herein to be sugars containing from 3 to 10 monosaccharide units.

[0062] During the hydrolysis of step (a), some or all of the hemicellulose present in the lignocellulosic material and some or all of the cellulose present in the lignocellulosic material may be hydrolyzed, which may suitably produce a mixture of pentose (i.e., C5 sugars, i.e., sugars whose molecules contain 5 carbon atoms) and hexose (i.e., C6 sugars, i.e., sugars whose molecules contain 6 carbon atoms) monosaccharides, disaccharides, and / or oligosaccharides.

[0063] The aqueous hydrolysis product solution may, for example, comprise pentose monosaccharides, hexose monosaccharides, pentose disaccharides, hexose disaccharides, and pentose-hexose disaccharides, pentose oligosaccharides, hexose oligosaccharides, and / or mixtures of pentoses and hexoses.Suitably, the aqueous 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 (e.g. maltose), glucose trimers, cellotriose, maltotriose, cellodextrin, dextrin, xylan-oligosaccharides, mannan-oligosaccharides, arabinan-oligosaccharides, and oligofructans. More suitably, the aqueous hydrolysis product solution may comprise at least one compound selected from the group consisting of mannose, glucose, galactose, arabinose, and xylose.

[0064] Preferably, the aqueous hydrolysis product solution comprises saccharides (including monosaccharides, disaccharides, 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, and most preferably 20% by weight or more, based on the total weight of the aqueous hydrolysis product solution. The upper limit of the sugar content in the aqueous hydrolysis product solution is formed by the solubility of the sugars in the solution. For glucose, a solubility of 909 grams of glucose per kg of water at 25° C. has been reported. For practical purposes, the aqueous hydrolysis product solution may suitably comprise a total amount of 45% by weight or less, based on the total weight of the aqueous hydrolysis product solution, (including monosaccharides, disaccharides, and / or oligosaccharides), more preferably 40% by weight or less.

[0065] In addition to sugars, the aqueous hydrolysis product solution suitably comprises hydrochloric acid. Preferably, the aqueous hydrolysis product solution has a hydrochloric acid concentration in the range of from 30.0 to 45.0% by weight, more preferably in the range of from 38.0 to 43.0% by weight, based on the weight of the combined hydrochloric acid and water.

[0066] Step (b) comprises separating the aqueous hydrolysate solution containing hydrochloric acid from the lignin, i.e. the aqueous hydrolysate solution obtained upon hydrolysis of at least a portion of the cellulose and at least a portion of the hemicellulose of the solid lignocellulosic material can be suitably separated from residual unhydrolyzed lignin.

[0067] The aqueous hydrolysate solution can be suitably separated from the residual lignin by any method known to be suitable by the skilled artisan, for example, as described in U.S. Pat. No. 2,778,751, European Patent No. 1,878,480, WO 2015 / 136044, and unpublished international application PCT / EP2017 / 071914. For example, the aqueous hydrolysate solution can be removed from any hydrolysis reactor in which the hydrolysis was carried out, via one or more outlets in such hydrolysis reactor. The residual lignin can be retained in such hydrolysis reactor and can be discarded at a later point in time. The removal of the residual lignin can be carried out, for example, in a batch or semi-continuous manner.

[0068] Suitably, steps (a) and (b) may be carried out in combination, particularly where the process, or parts of the process, are operated semi-continuously or continuously.

[0069] Advantageously, part or all of the aqueous hydrolysate solution containing both hydrochloric acid and sugars is fed directly to step (c).

[0070] Step (c) comprises heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of at least 60° C. to obtain a product solution containing 5-(chloromethyl)furfural and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent. Thus, step (c) suitably produces a 5-(chloromethyl)furfural-containing extraction solvent.

[0071] Without wishing to be bound by any type of theory, it is believed that the heating in step (c) suitably results in the dehydration of at least a portion of the sugars present in the hydrochloric acid-containing aqueous hydrolysate solution to 5-(chloromethyl)furfural. 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 sugars in the aqueous hydrolysate solution. Furthermore, additional hydrochloric acid may or may not be added, or additional water may or may not be added or removed, the latter of which may help to obtain an optimal hydrochloric acid concentration for step (c).

[0072] Preferably, step (c) comprises heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of 60° C. or higher, more preferably 70° C. or higher, to produce 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 produced may be simultaneously extracted from the product solution into the extraction solvent. Preferably, at least a portion of the 5-(chloromethyl)furfural is continuously or semi-continuously removed into such extraction solvent by in situ liquid-liquid extraction.

[0073] 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 aqueous hydrolysate solution to a temperature of 60° C. or higher, more preferably 70° C. or higher, in the presence of an extracting solvent, thereby generating 5-(chloromethyl)furfural, and extracting, preferably in situ, at least a portion of the generated 5-(chloromethyl)furfural into such an extracting solvent, thereby generating a 5-(chloromethyl)furfural-containing extracting solvent. After the conversion of the aqueous hydrolysate solution, more precisely the sugars therein, and the extraction of 5-(chloromethyl)furfural from the aqueous hydrolysate solution containing hydrochloric acid, such solution is suitably depleted of 5-(chloromethyl)furfural. Suitably, only a residual aqueous hydrochloric acid solution remains. Such a residual aqueous hydrochloric acid solution may advantageously be recycled to step (a), optionally after removal of any impurities and / or optionally after reconcentration of the hydrochloric acid. That is to say, preferably, a residual aqueous hydrochloric acid solution containing hydrochloric acid is obtained, which is recycled to step (a), optionally after adjusting the hydrochloric acid concentration.

[0074] Step (c) of the process according to the invention can suitably be carried out batchwise, semi-continuously or continuously in one or more reactors and / or vessels, which 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 in agitated dehydration reactors or non-agitated reactors in countercurrent, as described in more detail below.

[0075] 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.

[0076] 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.

[0077] 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 an extraction solvent present in the reaction mixture.

[0078] 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 hydrolyzate 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 producing 5-(chloromethyl)furfural. Then, at least a portion of the 5-(chloromethyl)furfural thus produced is extracted in situ into the extraction solvent, thereby producing a 5-(chloromethyl)furfural-containing extraction solvent. Preferably, such in situ extraction is thus carried out consecutively and / or simultaneously (i.e., in parallel) with the dehydration reaction.

[0079] Advantageously, step (c) is carried out in a continuous stirred tank reactor (CSTR). Suitably, such a CSTR may contain both (at least a portion of) the aqueous hydrolysate solution 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, for example a series liquid-liquid separator using a hydrophobic membrane, a hydrocyclone, or a spiral separator.

[0080] However, it may be advantageous to carry out step (c), preferably in a two-phase co-current or counter-current flow reactor, in which at least a portion of the stream of aqueous hydrolysate 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.

[0081] Without wishing to be bound by any type of theory, it is believed that by contacting the aqueous hydrolysate solution with the extraction solvent in situ, and optionally in countercurrent, the 5-(chloromethyl)furfural can be conveniently extracted into the extraction solvent immediately after its preparation, i.e., when the reaction proceeds in the presence of the extraction solvent, all of the 5-(chloromethyl)furfural can be simultaneously extracted into the extraction solvent.

[0082] Step (c) is advantageously carried out at a relatively elevated 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. to at most 120° C., even more preferably at most 110° C.

[0083] 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 megapascals to 10.0 megapascals.

[0084] Preferably, process step (c) continues for a period in the range of at least 0.25 hours, more preferably at least 0.50 hours and up to 10.00 hours, more preferably up to 4.00 hours, even more preferably up to 2.00 hours.

[0085] The extraction solvent is preferably an organic extraction solvent in which 5-(chloromethyl)furfural has a higher solubility at the temperatures and pressures applied during step (c) than in water.

[0086] The extraction solvent is preferably an organic extraction solvent; the organic extraction solvent has a boiling point, at the pressure applied during step (c), lower than the temperature applied during step (c); and / or the organic extraction solvent is essentially immiscible with water at the temperature applied during step (c); and / or The organic extraction solvent is essentially non-reactive with hydrochloric acid at the temperatures and pressures applied during step (c).

[0087] By organic extractant, it is meant herein that the extractant contains a compound with a hydrocarbon bond. By hydrocarbon bond, it is meant herein that the covalent bond between hydrogen and carbon atom. By essentially water-immiscible, it is meant herein that the organic extractant has a water solubility of less than 10 grams per 100 grams of water.

[0088] 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 an organic extraction solvent selected from the group consisting of C6-C10 aromatic hydrocarbons, C1-C10 chlorinated hydrocarbons, and C3-C10 ketones, and mixtures of two or more of these. By Cx compounds, it is understood herein that they are compounds containing "x" carbon atoms. By Cx-Cz compounds, it is understood herein that they are compounds containing 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 of these. More preferably, an aromatic extraction solvent is used, more preferably selected from the group consisting of benzene, toluene, and xylene.

[0089] 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.

[0090] 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.

[0091] Most preferably, the extraction solvent is toluene or 1,2-dichloroethane.

[0092] Preferably, the volume ratio between the hydrochloric acid-containing aqueous hydrolysate 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.

[0093] Preferably, the extraction solvent is denser or less dense than water, so that it can be easily separated from water by a simple two-phase separation, and this further allows for suitable operation in a preferably two-phase, countercurrent or cocurrent two-phase continuous flow reactor.

[0094] The resulting 5-(chloromethyl)furfural-containing extraction solvent can then be separated from the aqueous hydrolysate solution and / or reaction mixture.

[0095] Such separation may be accomplished in any manner known to those of skill in the art to be suitable, which may or may not include cooling, phase separation, membrane separation, sedimentation, and / or centrifugation.

[0096] Any separated 5-(chloromethyl)furfural-containing extraction solvent may optionally be dried to remove residual water.

[0097] To remove any residual 5-(chloromethyl)furfural from the remaining aqueous hydrolysate solution and / or reaction mixture, the remaining aqueous hydrolysate solution and / or reaction mixture may be optionally mixed with and / or washed with additional extraction solvent to extract such residual 5-(chloromethyl)furfural.

[0098] Preferably, step (c) is carried out in a two-phase countercurrent flow reactor, in which at least a portion of the flow of the aqueous hydrolysate 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 portion of the flow of the aqueous hydrolysate solution is contacted countercurrently with a flow of the extraction solvent, the 5-(chloromethyl)furfural-containing extraction solvent is already separated from the aqueous hydrolysate solution and / or the reaction mixture in the reactor.

[0099] The 5-(chloromethyl)furfural may or may not be isolated from the 5-(chloromethyl)furfural-containing extraction solvent.

[0100] Preferably, the method comprises the steps of: (i) isolating or separating the 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 5-(chloromethyl)furfural-containing extraction solvent, suitably in whole, 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; Further includes:

[0101] Preferably, the 5-(chloromethyl)furfural is further processed in non-isolated form in combination with the extraction solvent, i.e., preferably, the 5-(chloromethyl)furfural-containing extraction solvent is further processed in its entirety.

[0102] Alternatively, the 5-(chloromethyl)furfural is first isolated from the extraction solvent before such 5-(chloromethyl)furfural is further processed.

[0103] The 5-(chloromethyl)furfural can be isolated from the extraction solvent by any method known to those skilled in the art, such as evaporation and / or distillation. After removal of the 5-(chloromethyl)furfural, the extraction solvent may be recycled for reuse. The isolated 5-(chloromethyl)furfural may be converted to, for example, 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), using conventional techniques known in the art.

[0104] As mentioned above, advantageously, it is not necessary to immediately isolate 5-(chloromethyl)furfural from the extraction solvent. Any resulting 5-(chloromethyl)furfural-containing extraction solvent may be suitably further processed without isolating 5-(chloromethyl)furfural.

[0105] For example, the extraction solvent can advantageously be used as a solvent in: · reacting 5-(chloromethyl)furfural with an alkanol to produce 5-(alkoxymethyl)furfural ethers; reacting 5-(chloromethyl)furfural with water to produce 5-(hydroxymethyl)furfural; or · Processing to convert 5-(chloromethyl)furfural 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.

[0106] Therefore, the present invention also provides a method for producing 5-(alkoxymethyl)furfural, comprising the steps of: A method for converting solid lignocellulosic material containing hemicellulose, cellulose, and lignin, comprising the steps of: (a) hydrolyzing at least a portion of the hemicellulose and at least a portion of the cellulose of the solid lignocellulosic material with an aqueous hydrochloric acid solution at a temperature of 30° C. or less, the aqueous hydrochloric acid solution containing hydrochloric acid in an amount ranging from 40.0% to 51.0% by weight, based on the total weight of water and hydrochloric acid in the aqueous hydrochloric acid solution, to obtain an aqueous hydrochloric acid-containing hydrolysate solution; (b) separating the hydrochloric acid-containing aqueous hydrolysate solution from the lignin; and (c) heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of 60° C. or higher, preferably 70° C. or higher, to obtain a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent; Including, recovering the 5-(chloromethyl)furfural-containing extraction solvent; and 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 ranging from 10° C. to 90° C., more preferably below 50° C., to appropriately produce 5-(alkoxymethyl)furfural; The method further comprises:

[0107] The step of recovering the 5-(chloromethyl)furfural-containing extraction solvent 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 makes it possible to produce 5-(ethoxymethyl)furfural (EMF) in this process. Further preferences for steps (a), (b) and (c) are as described herein above.

[0108] Furthermore, the present invention also provides a method for producing 5-(methoxymethyl)furfural, comprising the steps of: A method for converting solid lignocellulosic material containing hemicellulose, cellulose, and lignin, comprising the steps of: (a) hydrolyzing at least a portion of the hemicellulose and at least a portion of the cellulose of the solid lignocellulosic material with an aqueous hydrochloric acid solution at a temperature of 30° C. or less, the aqueous hydrochloric acid solution containing hydrochloric acid in an amount ranging from 40.0% to 51.0% by weight, based on the total weight of water and hydrochloric acid in the aqueous hydrochloric acid solution, to obtain an aqueous hydrochloric acid-containing hydrolysate solution; (b) separating the hydrochloric acid-containing aqueous hydrolysate solution from the lignin; and (c) heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of 60° C. or higher, preferably 70° C. or higher, to obtain a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent; Including, recovering the 5-(chloromethyl)furfural-containing extraction solvent; and reacting 5-(chloromethyl)furfural with methanol in the presence of an extraction solvent, preferably at a temperature ranging from 10° C. to 90° C., more preferably 50° C. or less, to appropriately produce 5-(methoxymethyl)furfural; The method further comprises:

[0109] The step of recovering the 5-(chloromethyl)furfural-containing extraction solvent can be optionally combined with step (c), for example when using a two-phase, co-current or countercurrent 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.

[0110] Furthermore, the present invention also provides a method for producing 5-(hydroxymethyl)furfural, comprising the steps of: A method for converting solid lignocellulosic material containing hemicellulose, cellulose, and lignin, comprising the steps of: (a) hydrolyzing at least a portion of the hemicellulose and at least a portion of the cellulose of the solid lignocellulosic material with an aqueous hydrochloric acid solution at a temperature of 30° C. or less, the aqueous hydrochloric acid solution containing hydrochloric acid in an amount ranging from 40.0% to 51.0% by weight, based on the total weight of water and hydrochloric acid in the aqueous hydrochloric acid solution, to obtain an aqueous hydrochloric acid-containing hydrolysate solution; (b) separating the hydrochloric acid-containing aqueous hydrolysate solution from the lignin; and (c) heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of 60° C. or higher, preferably 70° C. or higher, to obtain a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent; Including, recovering the 5-(chloromethyl)furfural-containing extraction solvent; and reacting 5-(chloromethyl)furfural with water in the presence of an extraction solvent, preferably at a temperature ranging from 10° C. to 90° C., more preferably 50° C. or less, to suitably produce 5-(hydroxymethyl)furfural; The method further comprises:

[0111] The step of recovering the 5-(chloromethyl)furfural-containing extraction solvent 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.

[0112] Still further, the present invention also provides a method for producing 2,5-diformylfuran, comprising the steps of: A method for converting solid lignocellulosic material containing hemicellulose, cellulose, and lignin, comprising the steps of: (a) hydrolyzing at least a portion of the hemicellulose and at least a portion of the cellulose of the solid lignocellulosic material with an aqueous hydrochloric acid solution at a temperature of 30° C. or less, the aqueous hydrochloric acid solution containing hydrochloric acid in an amount ranging from 40.0% to 51.0% by weight, based on the total weight of water and hydrochloric acid in the aqueous hydrochloric acid solution, to obtain an aqueous hydrochloric acid-containing hydrolysate solution; (b) separating the hydrochloric acid-containing aqueous hydrolysate solution from the lignin; and (c) heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of 60° C. or higher, preferably 70° C. or higher, to obtain a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent; Including, recovering the 5-(chloromethyl)furfural-containing extraction solvent; and oxidizing 5-(chloromethyl)furfural to 2,5-diformylfuran in the presence of an extraction solvent; The method further comprises:

[0113] The step of recovering the 5-(chloromethyl)furfural-containing extraction solvent 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.

[0114] The above process advantageously allows the sugars resulting from hemicellulose and / or cellulose to be heated and converted into useful products without wasting energy in heating the lignin. Moreover, the above process advantageously allows the isolation of 5-(chloromethyl)furfural from the extraction solvent, avoiding any difficult and expensive steps.

[0115] When 5-(alkoxymethyl)furfural, 5-(hydroxymethyl)furfural, and / or diformylfurfural are produced from 5-(chloromethyl)furfural, hydrochloric acid is suitably regenerated as a by-product. Such hydrochloric acid may advantageously be used in direct recycling to step (a). More advantageously, such hydrochloric acid can be added as supplemental hydrochloric acid to the remaining aqueous hydrochloric acid-containing solution being recycled from step (c) to step (a). Such recycling of hydrochloric acid and the remaining aqueous hydrochloric acid-containing solution reduces the generation of chlorine-containing waste liquid, contributing to the economy, efficiency, and sustainability of the method of the present invention.

[0116] The non-limiting FIG. 1 below shows an example of a method according to the invention.

[0117] FIG. 1 shows a process according to the invention, in which step (a) is carried out semi-continuously in multiple reactors connected in series (i.e., a series of reactors) and step (c) of such process is carried out continuously in a countercurrent two-phase continuous flow reactor in the presence of an extraction solvent.

[0118] In the method shown in Figure 1, step (a) is carried out in a series of five hydrolysis reactors (R1-R5). The hydrolysis reactors are operated at a temperature of 20°C. The method is carried out in a series of cycles, each cycle operated for a cycle period of 8 hours.

[0119] 1 illustrates the start of a new cycle beginning at time "t". At the start of the new cycle, dry wood chips (101) have just been loaded into the reactor (R1) through the solids inlet line (102). The reactor (R1) is then filled with the intermediate aqueous hydrolysate solution (105e) exiting the storage vessel (103). It comprises a (partially prehydrolyzed) solid material containing cellulose and lignin, the hemicellulose fraction having already been partially hydrolyzed.

[0120] Thereafter, reactors (R1), (R2), (R3) and (R4) are transferred to the hydrolysis stage, and reactor (R5) is transferred to the residue removal stage.

[0121] In the first part of the new cycle, a plug of fresh aqueous hydrochloric acid solution (105a), having a hydrochloric acid concentration of 42.0% by weight and still essentially free of sugars, is introduced into reactor (R4), which forces a plug of intermediate aqueous hydrolysate solution (105b), which contains hydrochloric acid but already contains some sugars (i.e. coming from the material that was in reactor (R4)), out of reactor (R4) and into reactor (R3).

[0122] This plug of intermediate aqueous hydrolysate solution (105b) in turn pushes a second plug of intermediate aqueous hydrolysate solution (105c), containing hydrochloric acid but also sugars (i.e. from the optionally partially hydrolyzed lignocellulosic material already present in the previous reactor), out of reactor (R3) and into reactor (R2).

[0123] This second plug of intermediate aqueous hydrolysate solution (105c) in turn pushes a third plug of intermediate aqueous hydrolysate solution (105d), containing hydrochloric acid but also sugars (i.e. originating from the optionally partially hydrolyzed lignocellulosic material already present in the previous reactor), out of reactor (R2) and into reactor (R1).

[0124] As it is forced through reactor (R4) to reactor (R3), to reactor (R2) and then to reactor (R1), the intermediate aqueous hydrolysate solution absorbs more and more sugars from the material remaining in those reactors from the previous stage. The sugars concentration of the intermediate aqueous hydrolysate solution advantageously increases, thus providing a higher sugars concentration than could be achieved in a batch process.

[0125] A plug of intermediate aqueous hydrolysate (105d) pushes the final intermediate aqueous hydrolysate solution (105f) out of the reactor (R1).

[0126] The final hydrochloric acid-containing aqueous hydrolysate solution (105f) extruded from the reactor (R1) is passed through the liquid outlet line (112) to the countercurrent two-phase continuous flow reactor (114).

[0127] In the part of the cycle where a fresh plug of aqueous hydrochloric acid is introduced, residue (107), mostly lignin, is removed from the last reactor (R5) through the solids exit line (108).

[0128] At the end of the cycle, the intermediate aqueous hydrolysate solution is withdrawn from the reactor (R4) and forced into the reactor (R3) to separate it from the residue, which is left in the reactor (R4). The plug of intermediate aqueous hydrolysate solution withdrawn from the reactor (R4) and forced into the reactor (R3) pushes the plugs of the reactors (R3) and (R2) further forward. The plug of intermediate aqueous hydrolysate solution present in the reactor (R2) is forced out of the reactor (R2) into the reactor (R1). The last plug (105r) of intermediate aqueous hydrolysate solution present in the reactor (R1) is forced out of the reactor (R1) as shown by the dashed line and stored in the storage vessel (103). At the same time, the reactor (R5) can be loaded with a new batch of dry wood chips.

[0129] Once the cycle was completed, all reactors in the series had shifted positions: reactor (R5) was shifted to the position of reactor (R1), reactor (R1) was shifted to the position of reactor (R2), reactor (R2) was shifted to the position of reactor (R3), reactor (R3) was shifted to the position of reactor (R4), and reactor (R4) was shifted to the position of reactor (R5). As shown, the above cycle takes approximately 8 hours. The subsequent cycle can then begin.

[0130] FIG. 2 illustrates a subsequent cycle, beginning at time "t+8 hours." The dry wood chips in reactor (R5) may be flooded with an intermediate aqueous hydrolysate solution (205e) drawn from storage vessel (103). This is the intermediate aqueous hydrolysate solution stored in such storage vessel (103) similar to the intermediate aqueous hydrolysate solution (105r) in the prior cycle of FIG. 1. The subsequent cycle may then be carried out in a similar manner as described above for the prior cycle. Numbers (201), (202), (205a-f), and (205r), (207), and (208) indicate configurations similar to those shown in FIG. 1 by numbers (101), (102), (105a-f), and (105r), (107), and (108).

[0131] After a total of 5 cycles and a period of 40 hours, the situation is again exactly the same as in FIG.

[0132] In the above, all hydrochloric acid concentrations are on a mass basis based on the combined mass of water and hydrochloric acid.

[0133] As shown in both Figures 1 and 2, the final aqueous hydrolysate solution (105f) (205f) is pumped from the reactor (R1) and sent through a liquid outlet line (112) to a countercurrent two-phase continuous flow reactor (114). In such a countercurrent two-phase continuous flow reactor, the aqueous hydrolysate solution containing hydrochloric acid is then contacted with an extraction solvent, such as toluene, which is fed through a liquid inlet line (116). The countercurrent two-phase continuous flow reactor (114) is operated at 90°C.

[0134] From the top of the countercurrent two-phase continuous flow reactor (114), a stream of 5(chloromethyl)furfural-containing extraction solvent (120) is obtained through a liquid outlet line (130), and from the bottom of the countercurrent two-phase continuous flow reactor (114), a stream containing a residual hydrochloric acid-containing aqueous solution (122) is obtained through a liquid outlet line (124).

[0135] A bottoms stream (122) containing the residual hydrochloric acid-containing aqueous solution is optionally recycled through a reclaim line (126) (shown in dashed lines) to be reused as at least a portion of the aqueous hydrochloric acid solution described above. Optionally, small amounts of impurities can be removed, and an optional bleed stream (128) may also be present (both shown in dashed lines).

[0136] The top stream from reactor (114) containing 5-(chloromethyl)furfural-containing extractant (120) is sent through liquid outlet line (130) to further reactor (132). In the further reactor (132), the 5-(chloromethyl)furfural reacts with ethanol provided through liquid inlet line (134) in the presence of the extractant at a temperature of 50° C., thus producing 5-(ethoxymethyl)furfural and hydrochloric acid by-product. The 5-(ethoxymethyl)furfural is removed from reactor (132) through liquid outlet line (136) and can be further processed. The hydrogen chloride-containing by-product can be conveniently recycled through recycle line (138) and reused as supplemental hydrochloric acid to produce at least a portion of the aqueous hydrochloric acid solution described above. The present invention is further illustrated by the following non-limiting examples. EXAMPLES

[0137] Example 1: Hydrolysis of pine wood A certain amount of pine wood was hydrolyzed by treatment with an aqueous solution containing about 42% by weight of hydrochloric acid (HCl) at room temperature (about 20° C.). The solution after treatment was separated from the residue to produce an aqueous hydrochloric acid-containing hydrolysate solution, hereafter referred to as the hydrolysis product.

[0138] The hydrolysate product contained the components shown in Table 1. [Table 1]

[0139] Example 2: Conversion of hydrolysates The hydrolysis product obtained in Example 1 was used as substrate, without purification, for conversion to 5-chloromethylfurfural (CMF). Both glucose and mannose were considered as substrates for the formation of 5-chloromethyl. The experiments were carried out in a block of 12 parallel 7.7 mL stainless steel batch reactors equipped with Teflon liners, using magnetic stirring at 1200 rpm. The amount of hydrolysate substrate listed in Table 2 was weighed into the reactors, after which the extraction solvent was added. The extraction solvent was toluene in all experiments. Just before closing the reactors, an amount of aqueous solution containing about 37% by weight of hydrochloric acid (HCl) was added, which was then immediately inserted into a heating block, where the reactor contents were heated to the temperature (T) listed in Table 2. After the reaction time (t) shown in Table 2, the block was removed and cooled in an ice bath. The reactor block was then opened and the contents transferred to 8 mL glass vials. The phases were allowed to separate, and the aqueous layer was washed twice with 0.5 mL of toluene. Both phases were analyzed. The organic layer containing 5-chloromethylfurfural (CMF) and furfural was analyzed by gas chromatography. The aqueous layer containing hydroxymethylfurfural (HMF) was analyzed using ultra-performance liquid chromatography. Table 2 shows the results obtained using the hydrolysate substrate as the feed.

[0140] Table 3 shows a comparative experiment, which was carried out in a similar manner as above, using cellulose as substrate, dissolved in an aqueous solution containing about 37% by weight of hydrochloric acid (HCl). The results using the hydrolysate substrate show a high yield of 43.5% CMF. The difference with cellulose as substrate is considerable, with the highest yield under comparable conditions for cellulose being about 24.3% CMF yield. This clearly shows the significant superiority of the two-step conversion from cellulose feed by the method of the present invention.

[0141] [Table 2]

[0142] [Table 3]

[0143] Example 4: Conversion of 5-chloromethylfurfural Conversion of 5-chloromethylfurfural The amount of 5-chloromethylfurfural (CMF) listed in Table 3 was weighed into a 1.8 mL HPLC vial and dissolved in the amount of dichloromethane (DCM) solvent listed in Table 3. To this solution of CMF in dichloromethane solvent was added the amount of methanol (MeOH) listed in Table 3. Immediately after adding methanol to the reaction mixture, the vial was heated to the temperature (T) listed in Table 3 to initiate 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 4 provides a summary of the conversion to 5-chloromethylfurfural (CMF) and the yield and selectivity of 5-(methoxymethyl)furfural (MMF).

[0144] [Table 4]

Claims

1. 1. A method for converting solid lignocellulosic material containing hemicellulose, cellulose, and lignin, comprising the steps of: (a) hydrolyzing at least a portion of the hemicellulose and at least a portion of the cellulose of the solid lignocellulosic material with an aqueous hydrochloric acid solution at a temperature of 40° C. or less, the aqueous hydrochloric acid solution containing hydrochloric acid in an amount ranging from 40.0% to 51.0% by weight, based on the total weight of water and hydrochloric acid in the aqueous hydrochloric acid solution, to obtain an aqueous hydrochloric acid-containing hydrolysate solution; (b) separating the hydrochloric acid-containing aqueous hydrolysate solution from the lignin; and (c) heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of 60° C. or higher to obtain a product solution containing 5-(chloromethyl)furfural, and extracting the 5-(chloromethyl)furfural from the product solution into an extraction solvent; The method includes:

2. 2. The method of claim 1, wherein step (a) is carried out in multiple reactors, and one or more portions of the aqueous hydrochloric acid solution are transferred from one reactor to another and contacted with the optionally partially hydrolyzed solid lignocellulosic material in said reactors.

3. 3. The process of claim 1 or 2, wherein the aqueous hydrochloric acid solution is contacted in countercurrent with the optionally partially hydrolyzed solid lignocellulosic material.

4. 4. The method according to any one of claims 1 to 3, wherein in step (a) one or more portions of the aqueous hydrochloric acid solution, optionally together with another fluid, form a plug or liquid column, which is moving continuously or semi-continuously through a plurality of stationary reactors connected in series, each reactor containing a certain amount of already optionally partially hydrolyzed lignocellulosic material.

5. 5. The method of claim 1, wherein step (a) is carried out in a continuous or semi-continuous manner.

6. 6. The method of claim 1, wherein step (c) comprises heating at least a portion of the hydrochloric acid-containing aqueous hydrolysate solution to a temperature of 70° C. or higher to produce 5-(chloromethyl)furfural, and extracting at least a portion of the produced 5-(chloromethyl)furfural in situ into an extraction solvent to produce a 5-(chloromethyl)furfural-containing extraction solvent.

7. 7. The process of claim 6, 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 hydrolysate solution containing hydrochloric acid is contacted countercurrently with a stream of the extraction solvent.

8. 8. The method according to claim 6 or 7, wherein the extraction solvent comprises toluene and / or 1,2-dichloroethane.

9. A method according to any one of claims 3 to 6, wherein the residual aqueous solution containing hydrochloric acid which has been contacted with the solid lignocellulosic material is recycled to step (a), optionally after adjustment of the hydrochloric acid concentration.

10. (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 5-(chloromethyl)furfural-containing extraction solvent 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.

10. The method of claim 1, further comprising:

11. recovering the 5-(chloromethyl)furfural-containing extraction solvent; 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 produce 5-(alkoxymethyl)furfural; 10. The method of any one of claims 1 to 9, comprising:

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

10. The method of claim 1, further comprising:

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

10. The method of claim 1, further comprising:

14. recovering the 5-(chloromethyl)furfural-containing extraction solvent; and Oxidizing 5-(chloromethyl)furfural to 2,5-di-formylfuran in the presence of an extraction solvent. The method of any one of claims 1 to 9, further comprising:

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