BR112020014540B1 - PROCESS FOR CONVERTING A SOLID MATERIAL CONTAINING HEMICELULOSE, CELLULOSE AND LIGNIN - Google Patents

Abstract

A process for converting a solid material containing hemicellulose, cellulose and lignin, which process comprises the following steps: (i) hydrolyzing, at a temperature equal to or less than 40°C, preferably equal to or less than 30°C, at least a part of the hemicellulose solid material by contacting the solid material with a first aqueous hydrochloric acid solution, which first aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of 15.0% by weight or greater of 40.0% by weight, based on the amount by weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution, producing a remaining solid material and a first aqueous solution of hydrolyzate product; (ii) displacing the aqueous solution from the remaining solid material with a non-aqueous displacement fluid; (iii) hydrolyzing, at a temperature equal to or less than 40°C, preferably equal to or less than 30°C, at least part of the cellulose of the remaining solid material by replacing the non-aqueous displacement fluid with a second aqueous solution of hydrochloric acid, which second aqueous solution of hydrochloric acid has a concentration of hydrochloric acid in (...).

Description

FIELD OF INVENTION

[001] The present invention relates to a process for converting a solid material containing hemicellulose, cellulose and lignin, more specifically it refers to a process for converting a solid lignocellulosic material.

BASICS OF THE INVENTION

[002] With the dwindling supply of crude oil, the use of sustainable and renewable biomass materials is becoming increasingly important for the production of fuels and/or chemicals. Lignocellulosic materials such as wood or agricultural waste are suitable examples of this renewable biomass material. The production of fuels and/or chemicals from non-edible renewable and sustainable biomass materials, such as solid lignocellulosic material, is preferred, because such non-edible solid lignocellulosic material does not compete with food production.

[003] Various processes have been examined to convert solid lignocellulosic materials, such as wood or agricultural waste, into saccharides, which saccharides, in turn, can be conveniently converted into fuels and/or chemicals. Many of these processes involve the hydrolysis of solid lignocellulosic materials to produce saccharides. Examples of these hydrolysis methods include the Bergius Rheinau process.

[004] In the Bergius Rheinau process, solid lignocellulosic material, such as wood, is treated with at least one concentrated hydrochloric acid composition. During treatment, for example, about two-thirds of the wood may be dissolved by hydrochloric acid in the form of mono- and oligosaccharides, and the remainder may remain as lignin. The dissolved fraction may comprise mono- and oligosaccharides, together with water and hydrochloric acid. This fraction is also referred to as the hydrolyzate. The term "hydrolyzate" is well known to those skilled in the art to refer to any hydrolysis product(s).

[005] The hydrolysis of lignocellulosic material can also be conducted in two stages. In a first stage, so-called pre-hydrolysis can be conducted, in which the hemicellulose in the lignocellulosic material can be digested, giving a mixture, also referred to as pre-hydrolyzate, comprising xylose, arabinose, mannose, glucose and their oligomers such as saccharides. . In a second stage, a so-called main hydrolysis can be conducted, in which the portion of the lignocellulosic material remaining after pre-hydrolysis, consisting of a large extent of cellulose, can be subsequently digested with more concentrated HCl, to obtain mainly glucose and their oligomers as saccharides in the hydrolyzate.

[006] Examples of the Bergius Rheinau process include the Bergius Rheinau process, as modified by Riehm, as described, for example, in documents US2945777 and US2778751.

[007] Document US2945777 describes a process for the saccharification of softwood sawdust comprising a pre-hydrolysis step and a main hydrolysis step. In the first step, the sawdust is subjected to a temperature of about 15 to 30°C in a pre-hydrolysis with hydrochloric acid containing 34 to 37% HCl by weight for a time sufficient to substantially dissolve the hemicelluloses in an amount corresponding to about 22 to 26 percent of the wood substance dries and the solution obtained is subsequently separated from the solid residue. In the second step, the solid residue from said pre-hydrolysis is treated in a main hydrolysis with hydrochloric acid with about 40 to 42% HCl content and crystalline glucose is recovered from the sugar syrup obtained in said main hydrolysis. The process is exemplified in example 1 with a process in which pine sawdust is subjected to hydrolysis with 32% hydrochloric acid, after which the solution (hydrochloric acid with dissolved hydrolyzed hemicellulose) is filtered (i.e. drained) and the Wood residue is washed and dried. Subsequently, the main hydrolysis is carried out with 41% hydrochloric acid solution.

[008] Document US2778751 also refers to a process for the hydrolysis of wood with concentrated hydrochloric acid. A feature of the process, as disclosed by US 2,778,751, is that it uses a large amount of water, including washing acid which is dilute hydrochloric acid (0.5-3 HCl), close to strong hydrochloric acid (HCl to 41%), as is evident from figure 1 and the description. The described process comprises providing a plurality of separate stationary columns of pre-hydrolyzed cellulosic material containing lignin, said columns being connected in series to form a saccharification unit. The process includes continuously introducing concentrated hydrochloric acid containing about 40% by weight of HCl into said unit to hydrolyze cellulose into sugar. A column of liquid, consisting of defined contiguous zones, is caused to move continuously through the stationary wood, and the moving zones of the column are kept stationary by providing the reaction towers with inlets and outlets through which the necessary liquids are introduced into appropriate zones of the moving liquid column and through which appropriate quantities of liquid are withdrawn from other zones, respectively.

[009] Document US2778751, which dates back to 1957, indicates that, to ensure a completely uniform path of the complete liquid column, in which the concentration of the various zones remains constant, theoretically an infinite or at least very large number, of inputs and outputs must be provided. Document US2778751 optimistically indicates that in practice a relatively small number of such inputs and outputs have been found to be sufficient. It describes the intermittent advancement of the acid flow being balanced by a layer of highly concentrated, substantially sugar-free hydrochloric acid between an acidic sugar solution and a dilute acid, and the change of flow direction from the main tower to the next tower being rendered harmless by providing a sufficiently long-lasting layer of a concentrated sugar solution containing, for example, about 20 to 25 grams of sugar per 100 cm3 of solution.

[0010] The more recent document WO2016/082816, however, is less optimistic. Document WO2016/082816 describes how in a process comprising a first step, in which 35 to 37% hydrochloric acid is slowly fed to a reactor with biomass, and a second step, in which 40 to 42% hydrochloric acid is introduced through In this reactor, 40 to 42% hydrochloric acid displaces, based on its density, the acid already present at a lower concentration. The flow rate must be measured so that the displacement leads to a mere minimum mixing of the two acid fractions. Document WO2016/082816 further describes that also the acid must be removed from the reactor and notes that the residue in the reactor (lignin) binds to the hydrochloric acid. The acid was displaced by slowly introducing water. Again, it was noted that the displacement with water was carried out so slowly that the mixture between the acid and water could be kept as low as possible. With the addition of water, also hydrochloric acid bound to the lignin residue mentioned above is released, as stated. Document WO2016/082816 subsequently describes that residual hydrochloric acid could only be removed by applying large amounts of water, leading to a so-called “tail” in the concentration profile.

[0011] The recent document US2015/0275320 also describes a process for the hydrolytic rupture of plant biomass via hydrochloric acid. It describes a first phase beginning with the slow introduction of acid into the reactor and ending when the reactor is completely filled with acid. According to document US2015/0275320, the solid waste has a lower density at this point than the surrounding liquid and a floating situation more or less occurs in the reactor. The second phase described begins with the introduction of water from above and the displacement of the acid according to the density principle. This means that ideally there will be no mixing of the hydrolyzate solution having a heavier specific gravity with the water having a lighter specific gravity when there is a correspondingly slower and more uniform introduction. Document US2015/0275320 warns that if the introduction is too rapid, this could lead to a situation where the displacement is no longer uniform over the entire cross-section of the tube.

[0012] From the above, it becomes evident that the flow regime in a Bergius Rheinau process, as modified by Riehm, as described, for example, in documents US2945777 and US2778751, is far from buffer flow and a substantial backmix. This can be disadvantageous for several reasons.

[0013] Without excessive and costly washing, residual C5 saccharides (also called pentoses or C5-sugars) from a pre-hydrolysis step can be transferred to a main hydrolysis step. This reduces the purity of a product resulting from the main hydrolysis step. Unlike the C6 saccharides (also referred to as hexoses or C6 sugars) obtained in the main hydrolysis step, pentoses are, for example, difficult to ferment. Also for chemical conversions, relatively pure C6 saccharides are preferred rather than mixtures of C5 saccharides and C6 saccharides.

[0014] Secondly, hydrochloric acid can be transferred to the wash water used in a washing step and can only be removed from that wash water at great expense. In addition to hydrochloric acid being transferred to the wash water, for any modified process, it is preferred that the amount of water (or aqueous liquids other than hydrochloric acids required for hydrolysis of hemicellulose and cellulose) be used in hydrochloric acid-based hydrolysis of Biomass containing cellulose, hemicellulose and lignin is kept to a minimum as any water will need to be collected, stored in tanks and purified as it is easily contaminated with a small percentage of hydrochloric acid. As the handling of hydrochloric acid solutions has its requirements, it is preferred that the number of different hydrochloric acid solutions used is also kept to a minimum. If wash water is required, it is preferred that mixing of the wash water with the prehydrolyzate and hydrolyzate is kept to a minimum, as this dilutes the product streams and leads to washout of the acid-contaminated water.

[0015] It would be noted as an advance in the art the provision of a Bergius Rheinau process as described above, in which back-mixing can be substantially reduced and/or in which the purity of the product from the main hydrolysis step can otherwise be reduced. , be improved and/or in which the process can be carried out continuously or semi-continuously in a more efficient manner. It is also desirable that process control is preferably easy and straightforward, particularly in separating the hemicellulose hydrolyzate and cellulose hydrolyzate in the best possible way. The elements of such process control may be that the minimum number of pumps that are required (placing low-rate pumps differently over several reactors) and/or that the flow through the reactors resembles, to a reasonable extent, buffer flow and/or with the ability to keep the acid used for hemicellulose hydrolysis as much as possible from the acid used for cellulose hydrolysis, as such, can facilitate recycling of the acids.

SUMMARY OF THE INVENTION

[0016] Such a process was achieved with the process according to the invention.

[0017] Consequently, the present invention provides a process for converting a solid material containing hemicellulose, cellulose and lignin, which process comprises the following steps: (i) hydrolyze, at a temperature equal to or lower than 40°C, preferably equal to or less than 30°C, at least a portion of the hemicellulose of the solid material by contacting the solid material with a first aqueous hydrochloric acid solution, which first aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of equal to or greater than 15.0% by weight to less than 40.0% by weight, based on the amount by weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution, producing a remaining solid material and a first aqueous solution of hydrolyzate product; (ii) displacing the aqueous solution from the remaining solid material with a non-aqueous displacement fluid; (iii) hydrolyzing, at a temperature equal to or less than 40°C, preferably equal to or less than 30°C, at least part of the cellulose of the remaining solid material by replacing the non-aqueous displacement fluid with a second aqueous solution of hydrochloric acid, which second aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of equal to or greater than 40.0% by weight to equal to or less than 51.0% by weight, based on the amount by weight of water and hydrochloric acid in such second aqueous hydrochloric acid solution, producing a residue and a second aqueous solution of hydrolyzate product.

[0018] The process according to the invention may optionally further comprise an additional step (iv) of displacing the aqueous solution from the residue with additional non-aqueous displacement fluid.

[0019] Displacement with non-aqueous displacement fluid has several advantages.

[0020] Due to the composition of hemicellulose, hydrolysis of hemicellulose in step (i) can result in a first aqueous solution of hydrolyzate product containing a mixture of C5 saccharides and C6 saccharides and a remaining solid material comprising predominantly lignin and cellulose. Subsequent hydrolysis of the cellulose in the remaining solid material in step (iii) may subsequently result in a second aqueous solution of hydrolyzate product comprising, predominantly, as is believed, C6 saccharides.

[0021] As explained above, back-mixing of C5 saccharides from the first hydrolyzate product solution into the second hydrolyzate product solution is highly undesirable. The use of non-aqueous displacement fluid(s) allows the back-mixing of components from the first hydrolyzate product solution into the second hydrolyzate solution to be reduced. By reducing back-mixing, contamination of the second hydrolyzate product solution with C5 saccharides can be reduced.

[0022] Furthermore, non-aqueous displacement fluid can be used to compensate for volume losses during the process, which volume losses are due to the volume reduction of solid material. Compensation for such volume losses allows maintaining a sufficient flow rate and operating the process continuously or semi-continuously in a more efficient mode.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The process of the invention is illustrated by the following figures: Figures 1A, 1B and 1C illustrate a first cycle, starting at a time “t”, of a process according to the invention.

[0024] Figures 2A and 2B illustrate a second subsequent cycle, starting at a time “t+8 hours”, of the same process as figures 1A, 1B and 1C.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention relates to a process for converting a solid material containing hemicellulose, cellulose and lignin. Suitably such solid material is a solid lignocellulosic material.

[0026] By cellulose (also mentioned herein as a cellulosic material) is meant here a homopolysaccharide comprising glucose-based monomer units, such as cellobiose.

[0027] Hemicellulose (also mentioned here as hemicellulosic material) is also a polysaccharide, but different from cellulose. Hemicelluloses may, for example, comprise pentose monomer units such as xylose and arabinose, hexose monomer units such as glucose and mannose, hexuronic acid-based monomer units and deoxyhexose. Although some hemicelluloses may essentially consist of only a single type of monomer unit (e.g., xylans comprising essentially only xylose), most hemicelluloses may comprise several different types of monomer units (such as, for example, glucomannans comprising glucose and mannose).

[0028] The process according to the invention can use a wide variety of solid lignocellulosic materials as feedstock. Examples of solid lignocellulosic materials that can be appropriately used in the process of the invention include, for example, agricultural residues, such as stubble (e.g., corn stubble and soybean stubble), corn cobs, rice straw, rice husks, oat husks, corn fiber, cereal straw such as wheat, barley, rye and oat straw; grasses; forest products and/or forest residues, such as wood and wood-related materials, such as sawdust and bark; waste paper; sugar processing residues, such as bagasse and beet pulp; or mixtures thereof. More preferably, the solid lignocellulosic material is selected from the group consisting of wood, sawdust, bark, straw, hay, grasses, bagasse, corn stubble and/or mixtures thereof.

[0029] Preferably, the solid lignocellulosic material is inedible, to prevent the process from competing with food production. More preferably, the solid lignocellulosic material comprises or consists of wood. Wood can include softwood and/or hardwood and can originate from all types of trees, including spruce, pine, willow, larch, oak, birch, poplar, eucalyptus and other trees.

[0030] The solid lignocellulosic material can be conveniently washed, dried, roasted, roasted and/or reduced in particle size before being used as a feedstock in the process according to the invention. The solid lignocellulosic material may conveniently be supplied or present in various forms, including chips, pellets, powders, chunks, briquettes, crushed particles, ground particles, crushed particles or a combination of two or more of these. When the solid lignocellulosic material is wood, it may, for example, be provided or present in the form of wood dust, wood chips, wood pellets, wood briquettes, wood chips or a combination of two or more of these.

[0031] When the solid lignocellulosic material is wood, such wood is most preferably supplied or present in the form of wood chips. When the solid lignocellulosic material comprises grass, bagasse and/or stubble, such grass, bagasse and/or stubble is most preferably provided or present in the form of pellets. Such pellets advantageously provide an unstructured biomass, such as grass, bagasse and/or stubble, with a desired morphology. Such morphology can advantageously limit the collapse of material within the reactors upon hydrolysis of hemicellulose and cellulose, which could otherwise result in an undesirable pressure drop.

[0032] The process according to the invention can be a batch, semi-continuous or continuous process. As explained below, the process according to the invention can additionally be carried out in a reactor or a series of reactors.

[0033] The solid lignocellulosic material can be provided to a reactor, suitably in any manner known to the person skilled in the art. Solid lignocellulosic material can be, for example, supplied to a reactor by means of a feed hopper, conveyor belt, screw feeder or a combination thereof. The solid lignocellulosic material can be suitably loaded into a reactor, for example in a batch, semi-continuous or continuous mode. Preferably the solid lignocellulosic material is loaded into a reactor via one or more inlets located at the top of the reactor and/or via one or more side inlets located in the wall of the reactor.

[0034] Different types of reactor can be used. The process according to the invention can be carried out in any reactor known to the person skilled in the art as being suitable for a hydrolysis reaction. Such reactors are also referred to herein as “hydrolysis reactor(s)”.

[0035] Preferably the process is carried out in one or more reactors as described for a Bergius Rheinau process. Preferably such a reactor comprises a cylindrical vessel with its axis arranged in an essentially vertical or essentially horizontal manner. Preferably the reactor is an essentially vertical tubular reactor. If so desired, the reactor can be slightly inclined as, for example, described in document US20150275320. Preferably the reactor is conically tapered at the top and bottom. The diameter to height ratio may appropriately be in the range of equal to or greater than 1:10 (diameter:height) to equal to or less than 1:4 (diameter:height). The reactor may suitably be provided with a discharge opening that can be opened and closed, to allow the discharge of any residual lignin after the process. Preferably such discharge opening is located at the bottom of such a reactor.

[0036] Examples of suitable reactors include reactors as described, for example, in documents US2778751, EP1878480, WO2015/136044 and PCT/EP2017/071914. not pre-published. Aqueous hydrochloric acid solutions can advantageously flow through such hydrolysis reactors in an intermittent, continuous or semi-continuous mode.

[0037] Step (i) is preferably preceded by a loading step in which solid lignocellulosic material is loaded into the reactor as described in more detail above.

[0038] Step (i) suitably comprises hydrolyzing, at a temperature equal to or less than 40°C, preferably equal to or less than 30°C, at least part of the hemicellulose of the solid material by contacting the solid material with a first aqueous hydrochloric acid solution, which first aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of equal to or greater than 15.0% by weight to less than 40.0% by weight, based on the amount in weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution. Such step (i) suitably produces a first aqueous solution of hydrolyzate product. Furthermore, solid material will remain. Such remaining solid material suitably further comprises cellulose and lignin. This remaining solid material can also be referred to here as “pre-hydrolyzed solid material”.

[0039] By hydrolyze, respectively hydrolysis, is meant here the breaking of bonds between saccharide units in a polysaccharide, such as hemicellulose or cellulose, to obtain monosaccharides, disaccharides and/or oligosaccharides (by oligosaccharides are here meant chains of saccharides comprising in the range of 3 to 10 monosaccharide units). The product(s) of a hydrolysis is/are also referred to as “hydrolyzate”.

[0040] As explained above, hemicellulose hydrolysis is also known as “pre-hydrolysis” and the products of hemicellulose hydrolysis are also known as “pre-hydrolyzate”. Step (i) is thus also referred to here as “pre-hydrolysis” or “pre-hydrolyze”. The first hydrolyzate product solution obtained by hydrolysis of hemicellulose in step (i) is the first hydrolyzate product solution obtained in the process. It may also be referred to here as “prehydrolyzate”, “prehydrolyzate solution” or “hemicellulose hydrolyzate solution”. As explained above, such first hydrolyzate product solution may suitably contain a mixture of C5 saccharides and C6 saccharides. The first hydrolyzate product solution may, for example, contain xylose, arabinose, mannose, glucose, their oligomers and mixtures thereof.

[0041] As illustrated by the concentration of hydrochloric acid, the conditions for the pre-hydrolysis of step (i) are less severe than the conditions for the main hydrolysis of step (iii) described below. Under the conditions of step (i), hemicellulose can be selectively hydrolyzed. The hydrolysis of hemicellulose may have already been carried out by mere contact of the solid lignocellulosic material with the first aqueous solution of hydrochloric acid.

[0042] A high temperature is not required. Step (i) can thus be conveniently carried out at about room temperature (20°C). For practical purposes, step (i) is preferably carried out at a temperature equal to or greater than 0°C and preferably equal to or less than 30°C. It is believed that at temperatures above 30°C, cellulose may begin to become hydrolyzed and thus selectivity for hemicellulose hydrolysis may decrease. Furthermore, such cellulose hydrolysis may lead to lower yields in step (iii).

[0043] Step (i) can be carried out over a wide range of pressures. Conveniently, a pressure of about 0.1 MegaPascal (corresponding to about 1 bar) can be applied. All pressures here are absolute pressures

[0044] The concentration of hydrochloric acid for the first aqueous hydrochloric acid solution as indicated above is based on the amount by weight of water and hydrochloric acid contained in the first aqueous hydrochloric acid solution. Preferably the first aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of equal to or greater than 34.0% by weight to equal to or less than 39.9% by weight, more preferably in the range of equal to at or above 36.0% by weight to equal to or below 39.0% by weight, based on the amount by weight of water and hydrochloric acid contained in the first aqueous hydrochloric acid solution.

[0045] The combination of pressure, temperature and hydrochloric acid concentration can be optimized to obtain optimal selectivity in hemicellulose hydrolysis. Preferably a combination of pressure, temperature and hydrochloric acid concentration is applied such that the hydrochloric acid remains completely dissolved in the solution as hydrogen ions and chloride ions. More preferably the combination of pressure, temperature and concentration of hydrochloric acid is such that no molecular hydrochloric acid remains in solution. Another guideline on this aspect can, for example, be found by graphing the boiling point of an aqueous solution of hydrochloric acid as a function of the concentration of hydrochloric acid at the applied pressure. Such a graph was, for example, shown on the WEBSITE of “The Dietrich Process Systems”, in “Isothermal Absorption of Hydrogen Chloride”, pages 1-2, on the internet under URL: https://www.dedietrich.com/en/solutions -and-products/halide-treatment/hcl- treatment/absorption-hydrogen-chloride/isothermal, on January 30, 2018. The combination of pressure, temperature and hydrochloric acid concentration applied during step (i) is the most preferable since that the boiling point is not exceeded.

[0046] For practical purposes it is preferred that, appropriately at a pressure of about 0.1 MegaPascal, the result of multiplying the temperature (in °C) with the weight percentage (wt%) in the concentration of hydrochloric acid based in the amount by weight of water and hydrochloric acid contained in the first aqueous hydrochloric acid solution, is equal to or less than 1000. This is illustrated by formula (I) below Temperature (°C) x concentration (% by weight) < 1000 (I)

[0047] During step (i), hemicellulose is being hydrolyzed and the resulting saccharides become dissolved in the first aqueous solution of hydrochloric acid. Thus, in addition to water and hydrochloric acid, the first aqueous hydrochloric acid solution may or may not contain other compounds such as, for example, dissolved saccharides.

[0048] When added fresh to the process, the first aqueous hydrochloric acid solution (also referred to as the first fresh aqueous hydrochloric acid solution) preferably comprises only small amounts or, even essentially, no dissolved saccharides.

[0049] After absorbing the saccharides, the first aqueous hydrochloric acid solution is no longer fresh. Such a first aqueous solution of hydrochloric acid which additionally contains dissolved saccharides is also referred to herein as an “intermediate prehydrolyzate solution” or the “intermediate prehydrolyzate”. The intermediate prehydrolyzate solution may suitably contain saccharides (such as a mixture of C5 saccharides and C6 saccharides) dissolved in an aqueous solution of hydrochloric acid. Such an intermediate prehydrolyzate solution can thus also be referred to as such as an aqueous intermediate prehydrolyzate solution containing hydrochloric acid. The intermediate prehydrolyzate solution may further be appropriately used to contact another solid material, optionally partially prehydrolyzed, to appropriately absorb additional saccharides therefrom.

[0050] To obtain the best results, the solid material is preferably soaked in the first aqueous solution of hydrochloric acid. Such first aqueous hydrochloric acid solution may or may not contain saccharides.

[0051] Step (i) suitably produces a first aqueous solution of hydrolyzate product and pre-hydrolyzed solid material. The first hydrolyzate product solution is suitably an aqueous hydrolyzate solution. As explained, one skilled in the art will understand that such a solution appropriately contains the products of hemicellulose hydrolysis.

[0052] Without wishing to be limited by any type of theory, it is believed that, during pre-hydrolysis in step (i), predominantly any hemicellulose present in solid material can be hydrolyzed. This may suitably result in a first aqueous solution of hydrolyzate product which may comprise or consist of an aqueous solution containing hydrochloric acid and a mixture of pentose mono-di- and oligo-saccharides (i.e. C5 saccharides, i.e. sugars whose molecules contain five carbon atoms) and hexoses (i.e. C6 saccharides, i.e. sugars whose molecules contain six carbon atoms).

[0053] The first hydrolyzate product solution may include, for example, pentose monosaccharides, hexose monosaccharides, pentose disaccharides, hexose disaccharides, and pentose-hexose disaccharides, pentose oligosaccharides, hexose oligosaccharides and/or oligosaccharides of mixtures of pentoses and hexoses. Suitably, the first hydrolyzate 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 appropriately the first hydrolyzate 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.

[0054] Preferably the first hydrolyzate product solution contains a total amount of saccharides (including mono-, di- and/or oligosaccharides) equal to or greater than 2% by weight of saccharides, more preferably equal to or greater than 5% by weight of saccharides, even more preferably equal to or greater than 10% by weight of saccharides, and most preferably equal to or greater than 20% by weight of saccharides, based on the total weight of the first hydrolyzate product solution. The upper limit for the saccharide content in the first hydrolyzate product solution is formed by the solubility of the saccharides in the solution. For practical purposes, the first hydrolyzate product solution may suitably contain a total amount of saccharides (including mono-, di- and/or oligosaccharides) equal to or less than 45% by weight, more preferably equal to or less than 40%. by weight of saccharides, based on the total weight of the first hydrolyzate product solution.

[0055] In addition to saccharides, the first hydrolyzate product solution may suitably contain hydrochloric acid. Preferably, the first hydrolyzate product solution may have a hydrochloric acid concentration in the range of equal to or greater than 1.0% by weight to equal to or less than 40.0% by weight, more preferably in the range of equal to or greater than 10.0% by weight to equal to or less than 39.0% by weight, based on the weight of the combination of hydrochloric acid and water.

[0056] The remaining solid material may appropriately predominantly comprise lignin and cellulose. Preferably, the remaining solid material contains only small amounts or essentially no hemicellulose. Preferably, the hemicellulose content of solid material used as a feedstock for the process has been reduced by at least 85% by weight, more preferably at least 95% by weight, and preferably essentially 100% by weight. That is, preferably at least 85% by weight, more preferably at least 95% by weight, and most preferably essentially 100% by weight of the hemicellulose in the solid material used as a feedstock are hydrolyzed in step (i). The remaining solid material may thus comprise equal to or less than 10% by weight, more preferably equal to or less than 5% by weight, most preferably equal to or less than 1% by weight of the hemicellulose that was present in the material. solid used as a feed filler. Most preferably, the remaining solid material does not essentially comprise hemicellulose.

[0057] Step (ii) appropriately comprises displacing the aqueous solution from the remaining solid material with a non-aqueous displacement fluid. Such displacement may suitably comprise contacting the remaining solid material with the non-aqueous displacement fluid. Preferably the non-aqueous displacement fluid displaces any hydrochloric acid-containing and/or saccharide-containing aqueous solution from the pre-hydrolyzed solid material. For example, the non-aqueous displacement fluid may suitably displace any first aqueous hydrochloric acid solution, any intermediate prehydrolyzate solution and/or any first hydrolyzate product solution from the prehydrolyzed solid material. By displacement, it is understood here “taking your place”. Preferably, whenever, in the process of the invention, a preceding fluid is displaced by a successive fluid, the preceding fluid is forced from its location (such as, for example, its location in the solid material) and replaced by the succeeding fluid. Preferably, this displacement is carried out such that at least 80% by weight, more preferably at least 90% by weight, even more preferably at least 95% by weight and even more preferably 99% by weight of the preceding fluid, based on the total weight of the preceding fluid originally present, are displaced with the succeeding fluid. Most preferably, essentially all or 100% by weight, based on the total weight of the preceding fluid originally present, of the preceding fluid is displaced with the succeeding fluid.

[0058] The aqueous solution being displaced may suitably be any first aqueous solution of hydrochloric acid, any aqueous solution of intermediate prehydrolyzate, any first aqueous solution of hydrolyzate product and/or any other aqueous solution that is residing with and /or is in the remaining solid material. In this way, any such aqueous solution(s) can be appropriately separated from the remaining solid material (i.e., the pre-hydrolyzed solid material). Preferably, the non-aqueous displacement fluid is hydrophobic. Without wishing to be limited by any type of theory, it is believed that the non-aqueous, preferably hydrophobic displacement fluid can penetrate the remaining solid material and push the first hydrolyzate product solution being retained by such remaining solid material to out of such pre-hydrolyzed solid material.

[0059] By a non-aqueous displacement fluid is here preferably meant a fluid that preferably contains equal to or less than 1 kilograms per cubic meter (kg/m3), more preferably equal to or less than 0.2 kg/ m3 and even more preferably equal to or less than 0.02 kilograms per cubic meter (kg/m3) of water. Most preferably, the non-aqueous displacement fluid is essentially free of water. Preferably the non-aqueous displacement fluid is essentially immiscible with water and/or an aqueous solution of hydrochloric acid and/or a first aqueous solution of hydrolyzate product and/or a second aqueous solution of hydrolyzate product, as described herein.

[0060] Preferably the non-aqueous displacement fluid comprises or consists of an appropriately inert gas, or an appropriately inert liquid. More preferably, the non-aqueous displacement fluid is a gas comprising or consisting of nitrogen, oxygen, carbon dioxide, air or a mixture thereof; or a liquid comprising or consisting of one or more alkanes.

[0061] Most preferably the non-aqueous displacement fluid is a non-aqueous, suitably inert liquid.

[0062] Preferably, the non-aqueous displacement fluid is a non-aqueous, preferably hydrophobic liquid, having a density equal to or less than 1200 kilograms per cubic meter (kg/m3), even more preferably a liquid having a density equal to or less than 1000 kg/m3 and even more preferably a liquid having a density equal to or less than 800 kg/m3. Such density can be, for example, determined by ASTM method number ASTM D1217 - 15.

[0063] Preferably the non-aqueous displacement fluid is a non-aqueous liquid that is essentially a liquid at the temperatures as applied in the process according to the invention. Preferably, the non-aqueous displacement fluid has a boiling temperature, at ambient pressure (i.e. at 1 bar corresponding to 0.1 MegaPascal), equal to or greater than 30°C, more preferably equal to or greater than 50° C, even more preferably equal to or greater than 80°C and even more preferably equal to or greater than 100°C.

[0064] Preferably the non-aqueous displacement fluid has a melting temperature, at ambient pressure (that is, at 1 bar corresponding to 0.1 MegaPascal), equal to or less than 0°C, more preferably equal to or less than minus 5 degrees Celsius (-5°C), even more preferably equal to or less than minus 10 degrees Celsius (-10°C) and even more preferably equal to or less than minus 20 degrees Celsius (-20°C).

[0065] Preferably the non-aqueous displacement fluid has no flash point or has a flash point equal to or greater than 60°C, even more preferably equal to or greater than 80°C and even more preferably equal to or greater than 100°C. Such a flash point can, for example, be determined by ASTM method number ASTM D93.

[0066] Preferably the non-aqueous displacement fluid has a viscosity at 20°C equal to or less than 0.005 Pa^s (5 centipoise (cP)), more preferably equal to or less than 0.004 Pa^s (4 cP) and most preferably equal to or less than 0.002 Pa^s (2 cP). Such viscosity can, for example, be determined by ASTM method number ASTM D445 - 17a.

[0067] Preferably, the non-aqueous displacement fluid comprises or consists of one or more alkanes, more preferably one or more alkanes having in the range of equal to or greater than 5 to equal to or less than 20 carbon atoms, even more preferably an alkane having in the range of 6 or more to 16 carbon atoms. Alkanes can be cyclic or non-cyclic. Most preferably, the non-aqueous displacement fluid comprises or consists of one or more alkanes chosen from the group consisting of cyclic hexane, normal hexane, isohexane and other hexanes, normal heptane, isoheptane and other heptanes, normal octane , iso-octane and other octanes, normal nonane, iso-nonane and other nonanes, normal decane, iso-decane and other decanes, normal undecane, iso-undecane and other undecanes, normal dodecane, iso-dodecane and other dodecanes, normal tridecane , iso-tridecane and other tridecanes, normal tetradecane, iso-tetradecane and other tetradecanes, normal pentadecane, iso-pentadecane and other pentadecanes, normal hexadecane, isohexadecane and other hexadecanes.

[0068] More preferably, the non-aqueous displacement fluid comprises or consists of one or more alkanes having in the range of equal to or greater than 10 to equal to or less than 20 carbon atoms, even more preferably an alkane having in the range of equal to or greater than 10 to equal to or less than 16 carbon atoms. Heavier alkenes having a lower flash point, such as decanes, undecanes, dodecanes, tridecanes, tetradecanes, pentadecanes, hexadecanes and/or mixtures thereof, are preferred over lighter alkenes having a higher flash point, such as hexanes, heptanes, octanes, nonanes and mixtures thereof.

[0069] It is possible to use a non-halogenated alkane or a halogenated alkane. Preferably a non-halogenated alkane is used, but good results can also be obtained with, for example, perfluorohexane (i.e. 1,1,1,2,2,3,3,4,4,5,5,6,6 ,6-tetradecafluorohexane).

[0070] In an alternative embodiment according to the invention, the non-aqueous displacement fluid comprises or consists of an inert gas. For example, the non-aqueous displacement fluid may comprise or consist of nitrogen, oxygen, carbon dioxide or air.

[0071] The non-aqueous displacement fluid can be appropriately displaced again from the remaining solid material in step (iii). You may want to use non-aqueous displacement fluid again. In such a case, non-aqueous displacement fluid can be recovered from step (iii) and recycled to step (ii). In such a case, the non-aqueous displacement fluid in step (ii) is a non-aqueous displacement fluid recycled from step (iii). The non-aqueous displacement fluid recovered from step (iii) may optionally be purified and/or may optionally be stored in a displacement fluid storage container before being recycled to step (ii).

[0072] The non-aqueous displacement fluid may be supplied to any reactor in any manner known to be appropriate by one skilled in the art. Where a vertical or essentially vertically directed reactor is used, the non-aqueous displacement fluid may, for example, be supplied to such a reactor in an ascending or a descending mode.

[0073] The displacement may have already been carried out by merely placing the non-aqueous displacement fluid in contact with the pre-hydrolyzed solid material. To obtain best results, the pre-hydrolyzed solid material is preferably soaked in non-aqueous displacement fluid.

[0074] Step (ii) can be carried out over a wide range of pressures. Conveniently, a pressure of about 0.1 MegaPascal (corresponding to about 1 bar) can be applied.

[0075] Step (ii) can conveniently be carried out at about room temperature (20°C). For practical purposes, step (ii) is preferably carried out at a temperature equal to or less than 40°C, preferably equal to or less than 30°C. Most preferably step (ii) is carried out at a temperature in the range from equal to or greater than 0°C to equal to or less than 30°C.

[0076] Step (iii) suitably comprises hydrolyzing, at a temperature equal to or less than 40°C, preferably equal to or less than 30°C, at least a part of the cellulose of the remaining solid material by replacing the displacement fluid not aqueous by a second aqueous hydrochloric acid solution, which second aqueous hydrochloric acid solution has a hydrochloric acid concentration in the range of equal to or greater than 40.0% by weight to equal to or less than 51.0% by weight, based on the amount by weight of water and hydrochloric acid in such second aqueous hydrochloric acid solution. Step (iii) suitably produces a second aqueous solution of hydrolyzate product and a residue.

[0077] As explained above, cellulose hydrolysis is also known as “main hydrolysis” and the products of cellulose hydrolysis are also known “main hydrolyzate”. Step (iii) is thus also referred to here as “main hydrolysis”. The second hydrolyzate product solution obtained by hydrolysis of cellulose in step (iii) is the second hydrolyzate product solution obtained in the process. It may also be referred to as “main hydrolyzate”, “main hydrolyzate solution” or “main hydrolyzate product solution”. As explained above, such main hydrolysis predominantly produces glucose and its oligomers as saccharides in the main hydrolyzate.

[0078] During such main hydrolysis, a substantial part of the remaining bonds between the saccharide units in the remaining polysaccharides are hydrolyzed. Although most preferably essentially all remaining bonds between the saccharide units in the remaining polysaccharides are severed, the advantages of the invention can also be obtained when a portion of the bonds between such saccharide units remain intact.

[0079] The additional hydrolysis, respectively main hydrolysis, of the cellulose in the remaining solid material in step (iii) may have already been carried out by merely bringing the remaining solid material into contact with the second aqueous solution of hydrochloric acid.

[0080] Step (iii) can therefore, and conveniently, be carried out at about room temperature (20°C). For practical purposes step (iii) is preferably carried out at a temperature in the range from equal to or greater than 0°C to equal to or less than 30°C.

[0081] Step (iii) can be carried out over a wide range of pressures. Conveniently a pressure of about 0.1 MegaPascal (corresponding to about 1 bar) can be applied.

[0082] The concentration of hydrochloric acid for the second aqueous hydrochloric acid solution as indicated above is based on the amount by weight of water and hydrochloric acid contained in the second aqueous hydrochloric acid solution.

[0083] Preferably the second aqueous hydrochloric acid solution has a concentration of hydrochloric acid in the range of equal to or greater than 41.0% by weight to equal to or less than 45.0% by weight, based on the amount by weight of water and hydrochloric acid combined in the second aqueous hydrochloric acid solution.

[0084] During step (iii), the cellulose is being hydrolyzed and the resulting saccharides become dissolved in the second aqueous solution of hydrochloric acid. Furthermore, in addition to water and hydrochloric acid, the second aqueous hydrochloric acid solution may or may not contain other compounds such as, for example, dissolved saccharides.

[0085] When freshly added to the process, the second aqueous hydrochloric acid solution (also referred to as second fresh aqueous hydrochloric acid solution) preferably comprises only small amounts or even essentially contains no dissolved saccharides.

[0086] After absorbing the saccharides, the second aqueous hydrochloric acid solution is no longer fresh. Such a second aqueous hydrochloric acid solution, which may additionally contain dissolved saccharides, is also referred to herein as “intermediate hydrolyzate solution” or “main intermediate hydrolyzate solution”. The intermediate hydrolyzate solution may suitably contain saccharides (such as a mixture of C6 saccharides) dissolved in an aqueous hydrochloric acid solution. Such an intermediate hydrolyzate solution can thus also be referred to as an aqueous intermediate hydrolyzate solution containing hydrochloric acid. The intermediate hydrolyzate solution may further be, and appropriately, used to contact another solid material, optionally partially hydrolyzed, to appropriately absorb additional saccharides therefrom.

[0087] To obtain the best results, the remaining solid material is preferably soaked in the second aqueous hydrochloric acid solution. Such second aqueous hydrochloric acid solution may or may not contain saccharides.

[0088] Step (iii) suitably produces a second aqueous solution of hydrolyzate product and a residue. The second hydrolyzate product solution is suitably an aqueous solution. As explained, a person skilled in the art will understand that such a solution appropriately contains the products of cellulose hydrolysis.

[0089] The residue may appropriately comprise predominantly lignin. Preferably, the residue contains only small amounts or essentially no hemicellulose and only small amounts or essentially no cellulose. Preferably, the cellulose content of the remaining solid material (which was used at the beginning of step (iii) has been reduced by at least 85% by weight, more preferably at least 95% by weight, and preferably essentially 100% by weight. That is , preferably at least 85% by weight, more preferably at least 95% by weight, and most preferably essentially 100% by weight of the cellulose in the remaining solid material are hydrolyzed in step (iii). or less than 10% by weight, more preferably equal to or less than 5% by weight, most preferably equal to or less than 1% by weight of the cellulose that was present in the prehydrolyzed solid material, most preferably, the residue. does not essentially comprise cellulose and does not essentially comprise hemicellulose. The residue may further comprise hydrochloric acid.

[0090] The second hydrolyzate product solution may suitably comprise or consist of an aqueous solution containing hydrochloric acid and predominantly glucose saccharides.

[0091] Preferably, the second hydrolyzate product solution contains a total amount of saccharides (including mono-, di- and/or oligosaccharides) equal to or greater than 2% by weight of saccharides, more preferably equal to or greater than 5 % by weight saccharides, even more preferably equal to or greater than 10% by weight saccharides, and most preferably equal to or greater than 20% by weight saccharides, based on the total weight of the second hydrolyzate solution. The upper limit for the saccharide content in the second hydrolyzate product solution is formed by the solubility of the saccharides in the solution. For glucose, a solubility at 25°C of 909 grams of glucose per kilogram of water has been reported. For practical purposes, the second hydrolyzate product solution may suitably contain a total amount of saccharides (including mono-, di- and/or oligosaccharides) equal to or less than 45% by weight, more preferably equal to or less than 40%. by weight of saccharides, based on the total weight of the second hydrolyzate solution.

[0092] The second hydrolyzate product solution may include, for example, glucose monosaccharides, glucose disaccharides and glucose oligosaccharides. Suitably, the second hydrolyzate product solution may comprise one or more compounds selected from the group consisting of glucose and cellobiose.

[0093] The second hydrolyzate product solution may comprise some, but preferably comprises little or no pentose (C5 saccharides). Preferably, the second hydrolyzate product solution contains a total amount of C5 saccharides which is equal to or less than 20.0% by weight, more preferably equal to or less than 10.0% by weight, even more preferably equal to or less than 5.0% by weight, even more preferably equal to or less than 1.0% by weight, and most preferably equal to or less than 0.1% by weight, based on the total weight of saccharides in the second solution of hydrolyzate.

[0094] In addition to the saccharides, the second hydrolyzate product solution will appropriately contain hydrochloric acid. Preferably the second hydrolyzate product solution will have a hydrochloric acid concentration in the range of equal to or greater than 20.0% by weight, more suitably equal to or greater than 30.0% by weight to equal to or less than 50. 0% by weight, more suitably equal to or less than 45.0% by weight, more preferably in the range of equal to or greater than 38.0% by weight to equal to or less than 43.0% by weight, based in the weight of the combination of hydrochloric acid and water.

[0095] Optionally, the process according to the invention may additionally comprise an additional step (iv) comprising displacing the aqueous solution(s) of the residue with additional non-aqueous displacement fluid. Such additional non-aqueous displacement fluid may be the same or different from the non-aqueous displacement fluid used in step (ii). The preferences for this additional non-aqueous displacement fluid in an optional step (iv) are as described above for the non-aqueous displacement fluid used in step (ii). Also, temperature, pressure and other preferences for such an optional step (iv) are the same as described above for step (ii). If a step (iv) is included, the non-aqueous displacement fluid, upon completion of such step (iv), may be drained or otherwise removed from the waste again.

[0096] The process may additionally comprise an additional step in which the waste is discharged from the reactor involved. The residue can subsequently be washed and/or incinerated. As described above, the residue may suitably predominantly comprise lignin.

[0097] It is further believed that this lignin composition may be new and inventive in itself. Suitably, the invention thus further provides a lignin composition, which can be obtained by a process as described herein. Suitably, such a lignin composition may advantageously have a reduced sugar content and/or a reduced hydrochloric acid content, as compared to a lignin composition that has not been treated with a displacement fluid.

[0098] Suitable processes for obtaining a saccharide product from the prehydrolyzate solution (i.e., the first hydrolyzate product solution) and/or the main hydrolyzate solution (i.e., the second hydrolyzate solution) are described, for example, in documents WO2017/082723 and WO2016/099272. Preferably, the prehydrolyzate solution and/or the main hydrolyzate solution is suitably first mixed with a carrier liquid, in which the saccharides are insoluble and which has a boiling point higher than that of water to obtain an aqueous mixture. Subsequently, such aqueous mixture may be subjected to an evaporation step, to produce a vapor fraction comprising water and hydrochloric acid and a residue fraction comprising solid saccharides and the carrier liquid. The vapor fraction can advantageously be condensed, re-concentrated and recycled to the process to be used as a first or second hydrochloric acid solution. The waste fraction comprising solid saccharides and the carrier liquid can be conveniently recovered and passed into a separation vessel. Such a separation vessel may, for example, be a settling vessel or any other separator that is suitable for separating the saccharides from the carrier liquid. From the separation vessel, a saccharide product can be obtained. Furthermore, a stream of raw carrier liquid can be obtained that can be cleaned and recycled. Thus, preferably, the process according to the invention comprises one or more additional steps in which: - the first hydrolyzate product solution and/or the second hydrolyzate product solution is/are mixed with a carrier liquid, wherein the saccharides are insoluble and have a boiling point higher than that of water to obtain an aqueous mixture; - the aqueous mixture is subjected to an evaporation step, to produce a vapor fraction comprising water and hydrochloric acid and a residue fraction comprising solid saccharides and the carrier liquid; and - the waste fraction comprising solid saccharides and the carrier liquid is passed to a separation vessel to obtain a saccharide product.

[0099] It is believed that this saccharide product may be new and inventive on its own. Suitably, the invention thus further provides a saccharide composition, obtainable by a process as described herein.

[00100] As explained above, the process according to the invention can be carried out in one or more reactors.

[00101] Preferably the solid material remains stationary within such one or more reactors, while being placed in contact with one or more moving portions of the first aqueous solution of hydrochloric acid; and/or one or more moving portions of the non-aqueous displacement fluid; and/or one or more moving portions of the second aqueous hydrochloric acid solution.

[00102] More preferably, the solid material is residing in a stationary phase within a reactor and is brought into contact with a mobile phase moving through such a reactor, which mobile phase includes: - a zone comprising one or more portions of first aqueous hydrochloric acid solution; preferably followed by - a zone comprising one or more portions of a liquid non-aqueous displacement fluid; preferably followed by - a zone comprising one or more portions of second aqueous hydrochloric acid solution.

[00103] It is then understood here that the subsequent zone is brought into contact with the solid material at a point in time later than the point in time where the solid material was brought into contact with the preceding zone.

[00104] More preferably, the solid material is residing in a stationary phase within a reactor and is brought into contact with a mobile phase moving through such a reactor, which mobile phase includes: a) a zone comprising one or more portions of an intermediate prehydrolyzate solution; preferably followed by b) a zone comprising one or more portions of first aqueous hydrochloric acid solution, preferably fresh; preferably followed by c) a zone comprising one or more portions of a liquid non-aqueous displacement fluid; preferably followed by d) a zone comprising one or more portions of an intermediate hydrolyzate solution; preferably followed by e) a zone comprising one or more portions of a second aqueous hydrochloric acid solution, preferably fresh; optionally followed by f) an optional zone comprising one or more additional portions of additional liquid non-aqueous displacement fluid.

[00105] Without wishing to be limited by any type of theory, it is believed that the use of such a mobile phase conveniently allows each subsequent zone to displace the preceding zone of solid material.

[00106] Conveniently, the solid material containing hemicellulose, cellulose and lignin may be residing in a stationary phase within a reactor, and may be brought into contact in step (i) with one or more zones of a mobile phase moving through of such a reactor, including a zone comprising one or more portions of an intermediate prehydrolyzate solution and/or a zone comprising one or more portions of first aqueous solution of hydrochloric acid, preferably fresh, for producing a first aqueous solution of hydrochloric acid product. hydrolyzed and pre-hydrolyzed solid material. The mobile phase zones may suitably be zones a) and b), as described above.

[00107] Subsequently, any aqueous solution(s) may be displaced from the remaining solid material with a non-aqueous displacement fluid, by contacting such remaining solid material in step ( ii) with a subsequent zone of mobile phase moving through such reactor, which subsequent zone comprises one or more portions of a liquid non-aqueous displacement fluid by contacting such solid material remaining in step (ii) with a zone subsequent portion of the mobile phase moving through such a reactor, which subsequent zone comprises one or more portions of a liquid non-aqueous displacement fluid. It should be noted that in this case, the remaining solid material may still be appropriately residing in a stationary phase in the reactor. This zone of the mobile phase may suitably be zone c), as described above.

[00108] Subsequently, the non-aqueous displacement fluid may be displaced from the remaining solid material with a second aqueous solution of hydrochloric acid, by contacting the remaining solid material in step (iii) with one or more subsequent zones of the mobile phase that move through such a reactor, including a zone comprising one or more portions of an intermediate hydrolyzate solution and/or a zone comprising one or more portions of a second aqueous hydrochloric acid solution, preferably fresh, to produce a second aqueous product solution. of hydrolyzate and a residue. It should be noted that such remaining solid material may still be appropriately residing in a stationary phase in the reactor. The mobile phase zones may suitably be zones d) and e), as described above.

[00109] Subsequently, optionally, the second hydrolyzate solution may be displaced from the residue, by contacting such residue in an optional step (iv) with a subsequent zone of the mobile phase moving through such reactor, which subsequent zone comprises one or more additional portions of additional liquid non-aqueous displacement fluid. This zone of the mobile phase may suitably be zone f), as described above.

[00110] In the above processes, the mobile phase may suitably be an intermittent, semi-continuous or continuous mobile phase. Preferably, the mobile phase is a mobile phase moving semicontinuously or continuously.

[00111] More preferably, the process is carried out in a plurality of reactors. More preferably the process is carried out in a plurality of reactors connected in series, herein also referred to as a battery or series of reactors or as a reactor sequence.

[00112] Preferably, the process is carried out in a plurality of reactors (also referred to as columns) connected in series, as described for a Bergius Rheinau process. Examples of the Bergius Rheinau process include the Bergius Rheinau process, preferably as modified by Riehm, as described, for example, in US2778751. It is also possible for the process to be carried out in a plurality of reactors, as described in document WO2012/061085.

[00113] Preferably, the process is carried out in a plurality of reactors connected in series.

[00114] More preferably, the process is carried out in a reactor sequence of two or more reactors, in which, during steps (i), (ii), (iii), solid material is residing stationary within each reactor, while the first aqueous hydrochloric acid solution and/or the non-aqueous displacement fluid and/or the second aqueous hydrochloric acid solution is/are passed, preferably in a continuous or semi-continuous manner, from one reactor to another reactor .

[00115] Preferably, the process is carried out in a plurality of reactors connected in series: - in which one or more portions of first aqueous solution of hydrochloric acid are moving from one reactor to another and are brought into contact with the material stationary solid lignocellulosic, optionally partially pre-hydrolyzed, fixed in the reactors; and/or wherein one or more portions of second aqueous hydrochloric acid solution are moving from one reactor to another and are brought into contact with the stationary, optionally partially hydrolyzed, pre-hydrolyzed solid material fixed in the reactors. Preferably the one or more portions of first aqueous hydrochloric acid solution and/or one or more portions of second aqueous hydrochloric acid solution are moving in a continuous or semi-continuous manner.

[00116] More preferably, the first aqueous solution of hydrochloric acid is placed in countercurrent contact with the solid lignocellulosic material, optionally partially pre-hydrolyzed; and/or the second aqueous hydrochloric acid solution is placed in countercurrent contact with the pre-hydrolyzed, optionally partially hydrolyzed, solid material.

[00117] Portions of the first and/or second aqueous hydrochloric acid solution are preferably followed by one or more portions of a non-aqueous displacement fluid.

[00118] Thus, in step (i), one or more portions of first aqueous hydrochloric acid solution may conveniently form a buffer or liquid column, optionally in combination with a non-aqueous displacement fluid, which buffer or liquid column is movement in a continuous or semi-continuous path through a plurality of reactors, each reactor containing a quantity of stationary solid lignocellulosic material, optionally already partially pre-hydrolyzed, (that is, solid material containing cellulose, hemicellulose and lignin). When step (i) is carried out countercurrently, one or more portions of fresh first aqueous hydrochloric acid solution may be conveniently supplied to a reactor retaining the solid lignocellulosic material, where the hemicellulose in such solid lignocellulosic material has already been partially pre-treated. hydrolyzed to the greatest degree. Saccharides may be absorbed from such lignocellulosic material, already partially pre-hydrolyzed, and the one or more portions of first aqueous hydrochloric acid solution (appropriately now containing some saccharides) may subsequently move from the outlet of such a reactor to the entry of a preceding reactor, which preceding reactor retains the lignocellulosic material that had undergone less pre-hydrolysis.

[00119] While moving, preferably countercurrently, from each reactor to another reactor, the above first aqueous hydrochloric acid solution can appropriately absorb more and more saccharides. Thus, the saccharide concentration of the first aqueous solution of hydrochloric acid can, appropriately gradually, increase until a first aqueous solution of hydrolyzate product containing hydrochloric acid is produced.

[00120] When carried out countercurrently, step (i) is preferably carried out in a plurality of “x” reactors FR1 to FRx, connected in series, in which fresh lignocellulosic material can be introduced and/or be residing in reactor FR1 and each reactor FR2 to subsequent FRx may contain partially pre-hydrolyzed lignocellulosic material, where the degree of pre-hydrolysis of the lignocellulosic material may increase in the direction from reactor FR2 to FRx; and wherein one or more portions of the first fresh aqueous hydrochloric acid solution can be introduced into the last FRx reactor and can move countercurrently from the FRx reactor to FR1 reactor. Suitably, such portions of first aqueous hydrochloric acid solution may gradually absorb saccharides from the optionally already partially pre-hydrolyzed lignocellulosic material to thereby produce an aqueous pre-hydrolyzate solution containing hydrochloric acid which can be removed from the FR1 reactor. Such an aqueous prehydrolyzate solution containing hydrochloric acid will advantageously be richer in saccharides than if step (i) had been carried out in a single reactor. In FRx reactor, a pre-hydrolyzed solid material can be obtained, which can be appropriately discarded from the FRx reactor.

[00121] Similarly, in step (iii), one or more portions of second aqueous hydrochloric acid solution may conveniently form a buffer or liquid column, optionally in combination with a non-aqueous displacement fluid, which buffer or liquid column is moving in a continuous or semi-continuous path through a plurality of stationary reactors, each reactor containing a quantity of remaining stationary solid material, optionally already partially hydrolyzed (that is, remaining solid material containing cellulose and lignin).

[00122] When step (iii) is carried out countercurrently, one or more portions of fresh second aqueous hydrochloric acid solution can be conveniently supplied to a reactor retaining remaining solid material that had already been partially hydrolyzed to the greatest degree. Saccharides may be absorbed from such remaining solid material, already partially hydrolyzed, and the one or more portions of second aqueous hydrochloric acid solution (appropriately now containing some amount of saccharides) may subsequently move from the outlet of such reactor to the inlet of a preceding reactor, which preceding reactor retains the remaining solid material that had undergone less hydrolysis.

[00123] While moving, preferably countercurrently, from one reactor to another reactor, the second aqueous hydrochloric acid solution can appropriately absorb more and more saccharides. Thus, the saccharide concentration of the second aqueous solution of hydrochloric acid can, appropriately gradually, increase until a second aqueous solution of hydrolyzate product containing hydrochloric acid is produced.

[00124] When carried out countercurrently, step (iii) is preferably carried out in a plurality of “y” reactors SR1 to SRy, connected in series, in which remaining fresh solid material is residing in or introduced into reactor SR1 and each subsequent reactor SR2 SRy contains pre-hydrolyzed, partially hydrolyzed solid material, where the degree of hydrolysis of the remaining solid material increases in the direction from SR2 to SRy; and wherein one or more portions of fresh second aqueous hydrochloric acid solution are introduced into the last reactor SRy and move countercurrently from reactor SRy to reactor SR1, and wherein such portions of second aqueous hydrochloric acid solution gradually absorb saccharides from the pre-hydrolyzed solid material, optionally already partially hydrolyzed, to thus produce an aqueous solution of hydrolyzate, containing hydrochloric acid, which can be removed from the SR1 reactor. Such an aqueous hydrolyzate solution containing hydrochloric acid will advantageously be richer in saccharides than if step (iii) had been carried out in a single reactor. In the SRy reactor a hydrolyzed lignocellulosic material can be obtained, which can be appropriately discarded from the SRy reactor.

[00125] Preferably, the process according to the invention is carried out in a plurality of reactors, connected in series, comprising 2 or more reactors, more preferably in the range of equal to or greater than 2 to equal to or less than 16 reactors, even more preferably in the range of equal to or greater than 4 to equal to or less than 8 reactors and most preferably in the range of equal to or greater than 4 to equal to or less than 7 reactors.

[00126] It is possible for step (i) to be carried out in a first set of reactors connected in series and for step (iii) to be carried out in a second set of reactors, optionally separate, connected in series. Suitably, each such set of reactors comprises 2 or more reactors, preferably 2 to 10, more preferably 2 to 8 reactors and most preferably 2 to 4 reactors.

[00127] Preferably, however, step (i) and step (iii) are carried out within a combined set of reactors connected in series. Preferably, such a combined set of reactors connected in series comprises 2 or more reactors, more preferably in the range of equal to or greater than 2 to equal to or less than 16 reactors, even more preferably in the range of equal to or greater than 4 to equal to at or less than 8 reactors and most preferably in the range from equal to or greater than 4 to equal to or less than 7 reactors.

[00128] It is preferred that the number of reactors in which step (iii) is carried out is greater than the number of reactors in which step (i) is carried out. Preferably, the number of reactors in which step (iii) is carried out is 1.5 to 3 times the number of reactors in which step (i) is carried out. Thus, if step (i) is carried out in 2 reactors, step (iii) is preferably carried out in 3 to 6 reactors.

[00129] When it is desirable for the process to be carried out in a continuous or semi-continuous mode in a plurality of reactors, it is important that the flow rate can be adjusted so that the process in each reactor can be carried out in an optimal mode. Without wishing to be limited by any type of theory, it is believed that, as a consequence of hemicellulose hydrolysis and cellulose hydrolysis, the volume of solid material in the reactors may shrink. To compensate, it may be desirable to adjust the volume of non-aqueous displacement fluid being used.

[00130] The process according to the invention can advantageously be carried out in a continuous or semi-continuous mode. For example, the process may be carried out in a plurality of reactors in a sequence of cycles, wherein within each cycle: - at least part of the hemicellulose of a solid lignocellulosic material (i.e. a solid material containing hemicellulose, cellulose and lignin ) is hydrolyzed in a first reactor sequence of “x” reactors FR1 to FRx, in which fresh solid lignocellulosic material is introduced into reactor FR1 and each subsequent reactor FR2 to FRx contains partially pre-hydrolyzed solid material; and wherein one or more portions of first aqueous hydrochloric acid solution, preferably fresh, are introduced into the last FRx reactor by pushing forward a first liquid column, said first liquid column containing previous portions of the first aqueous hydrochloric acid solution, in a countercurrent direction from reactor FRx to reactor FR1; producing pre-hydrolyzed solid material residing in FRx reactor and a first aqueous hydrolyzate product solution containing hydrochloric acid residing in FR1 reactor, thereafter the first aqueous hydrolyzate product solution containing hydrochloric acid is recovered from the FR1 reactor and any solutions aqueous are displaced from the pre-hydrolyzed solid material with a non-aqueous displacement fluid, suitably the first, in an FRx reactor; - at least part of the cellulose of a pre-hydrolyzed solid material is hydrolyzed in a second reactor sequence of “y” reactors SR1 to SRy, wherein fresh pre-hydrolyzed solid material is residing in reactor SR1 and each subsequent reactor SR2 to SRy contains pre-hydrolyzed, partially hydrolyzed solid material; and wherein one or more portions of second aqueous hydrochloric acid solution, preferably fresh, are introduced into the last SRy reactor by pushing forward a second column of liquid, said second column of liquid containing previous portions of second aqueous hydrochloric acid solution, in a countercurrent direction from reactor SRy to reactor SR1; producing a residue residing in reactor SRy and a second aqueous solution of hydrolyzate product containing hydrochloric acid residing in reactor SR1; thereafter the second hydrolyzate product aqueous solution containing hydrochloric acid is recovered from reactor SR1; and optionally any aqueous solution(s) is(are) displaced from the residue with a non-aqueous displacement fluid, suitably the second, in SRy reactor and then discharged from from the SRy reactor; after that - respective reactors FR1 to FRx-1 switch to the respective reactor position FR2 to FRx, - respective reactor FRx switches to the respective reactor position SR1, - respective reactors SR1 to SRy-1 switch to the respective reactor position SR2 a SRy, and - respective reactor SRy switches to the respective reactor position FR1.

[00131] By switching from one reactor to the position of another reactor it is here preferably understood that the one reactor takes its place, that is, the function, of the other reactors in the first or second mentioned sequence of reactors.

[00132] Each cycle is preferably carried out within a period of time referred to as the cycle period. The cycle period preferably is in the range of equal to or greater than 4 hours, more preferably equal to or greater than 6 hours, to equal to or less than 24 hours, more preferably equal to or less than 12 hours. Most preferably, the cycle period is in the range of 7 hours or more to 9 hours or less. For example, the cycle period may be 8 hours.

[00133] The partially remaining solid material initially residing in FR2 to FRx reactors can conveniently be obtained in one or more previous cycle periods.

[00134] Similarly, the remaining partially hydrolyzed solid material, initially residing in reactors SR2 to SRy, can be appropriately obtained in one or more previous cycle periods.

[00135] Preferences for reaction conditions, the lignocellulosic material, the first aqueous hydrochloric acid solution, the second aqueous hydrochloric acid solution, the first hydrolyzate product solution, the second hydrolyzate product solution, the remaining solid material and non-aqueous displacement fluids, any mobile phases and any other aspects are all as described herein above.

[00136] During a cycle period, the rate at which reactants are supplied to the reactors can vary widely, especially as some reactants, such as wood, can be supplied to the reactors on an intermittent basis. When averaged over a complete cycle period, the average weight ratio of the amount of the first aqueous hydrochloric acid solution to the amount of solid (lignocellulosic) material (on a dry basis) preferably is in the range of equal to or greater than 0 .5:1 (weight/weight) to equal to or less than 10:1 (weight/weight), more preferably equal to or less than 7:1 (weight/weight) and most preferably equal to or less than 5: 1 (weight/weight). Similarly, when averaged over a complete cycle period, the average weight ratio of the amount of second aqueous hydrochloric acid solution to the amount of solid (lignocellulosic) material (on a dry basis) preferably is in the range of equal to or greater at 0.5:1 (w/w) to equal to or less than 10:1 (w/w), more preferably equal to or less than 7:1 (w/w) and most preferably equal to or less than 5:1 (weight/weight).

[00137] When averaged over a complete cycle period, the average weight ratio of amount of non-aqueous displacement fluid to amount of lignocellulosic material preferably is in the range of equal to or greater than 2:1 (weight/weight) up to equal to or less than 4:1 (weight/weight)..

Example 1

[00138] Non-limiting figures 1A, 1B, 1C, 2A and 2B illustrate an example of the process according to the invention.

[00139] The illustrated process is carried out in a reactor sequence of 6 hydrolysis reactors (R1 to R6). Hydrolysis reactors are operated at a temperature of 20°C and a pressure of 0.1 MegaPascal. The process is operated in a sequence of cycles, each cycle being carried out within an 8 hour cycle period.

[00140] Figure 1A illustrates the beginning of a new cycle. After starting a new cycle, dry wood chips (101) have just been loaded into the reactor (R1) via the solids inlet line (102). Reactor (R2) contains an intermediate prehydrolyzate solution and a solid material containing cellulose and lignin. Hemicellulose is already, at least partially, hydrolyzed. Reactor (R3) contains a displacement fluid (such as, for example, isooctane) and a solid material containing cellulose and lignin. Reactors (R4) and (R5) each contain an intermediate hydrolyzate solution. The reactor intermediate hydrolyzate solution (R4) may contain a greater amount of saccharides than the reactor intermediate hydrolyzate solution (R5), as explained below. Furthermore, reactors (R4) and (R5) contain a solid material containing lignin. The cellulose is already, at least partially, hydrolyzed. Reactor (R6) contains a displacement fluid (such as, for example, isooctane) and a residue. The residue is a solid material containing lignin.

[00141] As illustrated in Figure 1B, during a first part of the cycle, reactor (R1) is flooded with a buffer (104c) of intermediate pre-hydrolyzate solution from a storage container (103), a buffer (104a) of first fresh aqueous hydrochloric acid solution is introduced to reactor (R2), a buffer (105a) of second fresh aqueous hydrochloric acid solution is introduced to reactor (R5) and a buffer (106d) of displacement fluid is drained from of the reactor (R6).

[00142] After the reactor (R1) has been flooded with a buffer (104c when going into R1, 104d when being pushed out of R1) of intermediate prehydrolyzate solution from a storage container (103), a buffer (104a) of first fresh aqueous hydrochloric acid solution, having a hydrochloric acid concentration of 37.0% by weight and still containing essentially no saccharides, is introduced into the reactor (R2), thus pushing forward a buffer (104b) of intermediate prehydrolyzate solution containing hydrochloric acid at a concentration of about 37.0% by weight, but also already containing some saccharides (i.e., saccharides derived from the solid material that was residing in reactor (R2)), from from reactor (R2) to reactor (R1). The intermediate prehydrolyzate solution buffer (104b) pushes the buffer (104d) out of the reactor (R1). Buffer (104d) previously contained intermediate prehydrolyzate solution, but had now absorbed sufficient saccharides and had become a first final hydrolyzate product solution. Such first final hydrolyzate product solution may suitably be advanced to one or more subsequent processes or devices, where, optionally, hydrochloric acid could be removed from the pre-hydrolyzate solution and recycled.

[00143] During the same first part of the cycle, a buffer (105a) of fresh second aqueous hydrochloric acid solution, having a hydrochloric acid concentration of 42.0% by weight and not yet containing essentially saccharide, is introduced into the reactor ( R5), thus pushing forward a buffer (105b) of intermediate hydrolyzate solution, containing hydrochloric acid at a concentration of about 42.0% by weight, but also already containing some saccharides (i.e., derivatives of the solid material that was residing in reactor (R5)), from reactor (R5) to reactor (R4). This buffer (105b) in turn pushes forward a second buffer (105c) of intermediate hydrolyzate solution, containing hydrochloric acid at a concentration of about 42.0% by weight, but also containing saccharides (i.e. derived from the solid material that was residing in previous reactors), from reactor (R4) to reactor (R3). While being pushed from reactor (R5) to reactor (R4) and further to reactor (R3), the intermediate hydrolyzate solution increasingly absorbs the saccharides from the solid material remaining in such reactors from earlier stages. The saccharide concentration of the intermediate hydrolyzate solution advantageously increases, thus allowing a saccharide concentration to be obtained which is greater than the saccharide concentration obtained in a batch process.

[00144] The buffer (105c) of intermediate hydrolyzate solution, being pushed from the reactor (R4) to reactor (R3), pushes a buffer (106c) of displacement fluid out of the reactor (R3).

[00145] During this same first part of the cycle, an additional plug (106d) of displacement fluid is drained from the reactor (R6), leaving behind a residue containing lignin.

[00146] During a second part of the cycle, as illustrated by Figure 1C, a plug (106a) of displacement fluid is introduced into the reactor (R2). This plug (106a) may or may not contain parts of the displacement fluid plug (106c) that have been pushed out of the reactor (R3). Advantageously, the volume of displacement fluid in plug (106a) can be adjusted, for example, by adding more or less displacement fluid, so as to compensate for volume losses due to volume reduction of solid material. This allows the technician to assure that all reactors remain sufficiently filled with volume and that a sufficient flow rate can be maintained.

[00147] The displacement fluid plug (106a) being introduced into reactor (R2), appropriately pushes forward the plug (104a) that was residing in reactor (R2). Buffer (104a) previously contained only the first fresh aqueous hydrochloric acid solution, but it had, during this time, absorbed saccharides from the solid material in reactor (R2) and had become an intermediate prehydrolyzate solution. Buffer (104a) is pushed out from reactor (R2) to reactor (R1), thereby pushing forward buffer (104b) of intermediate prehydrolyzate solution out of the reactor (R1) into the storage vessel (103). , as illustrated in Figure 1C.

[00148] Furthermore, appropriately, a displacement fluid plug (106b) is introduced into the reactor (R5). The displacement fluid plug (106b) being introduced into reactor (R5), appropriately pushes forward the plug (105a) that was residing in reactor (R5). Buffer (105a) previously contained only the second fresh aqueous hydrochloric acid solution, but it had, during this time, absorbed saccharides from the solid material in reactor (R5) and had become an intermediate hydrolyzate solution. Buffer (105a) is pushed out of the reactor (R5) into the reactor (R4), thereby pushing forward the buffer (105b) of intermediate prehydrolyzate solution out of the reactor (R4) into the reactor (R3). The intermediate prehydrolyzate solution buffer (105b) pushes forward the buffer (105c) that was residing in reactor (R3). Buffer (105c) previously contained intermediate hydrolyzate solution, but had now absorbed sufficient saccharides and had become a second aqueous solution of hydrolyzate product. Such a second hydrolyzate product solution can also be referred to as a hydrolyzate product solution. Buffer (105c) of the second hydrolyzate product solution is pushed out from the reactor (R3). Such second hydrolyzate product solution may be appropriately advanced to one or more subsequent processes or devices, where optionally the hydrochloric acid could be removed from the hydrolyzate solution and recycled.

[00149] During this same second part of the cycle, residue (107) containing lignin can appropriately be removed from the reactor (R6) via the solid outlet line (108) and reactor (R6) can be charged with a new batch of dry wood chips (shown as (201) in Figure 2A).

[00150] The cycle has now been completed and all reactors have been switched from one position in the reactor sequence. That is: - reactor (R6) has now been switched to a position previously occupied by reactor (R1); - reactor (R1) has now been switched to a position previously occupied by reactor (R2); - reactor (R2) has now been switched to a position previously occupied by reactor (R3); - reactor (R3) has now been switched to a position previously occupied by reactor (R4); - reactor (R4) has now been switched to a position previously occupied by reactor (R5); e - reactor (R5) has now been switched to a position previously occupied by reactor (R6). As indicated, the above cycle takes about 8 hours. A subsequent cycle can now be started.

[00151] The situation in which all reactors switched in one position was illustrated in Figure 2A. Figure 2A illustrates the start of a subsequent cycle, at a time “t+8 hours”. The dried wood chips in what was previously the reactor (R6) and is now the reactor (R1) can be flooded with a buffer (204c) of intermediate prehydrolyzate solution taken from the storage container (103). This is the same intermediate prehydrolyzate solution that was stored in such a storage container (103) as intermediate prehydrolyzate solution buffer (104b) in the second part of the previous cycle, and illustrated in Figure 1C. The subsequent cycle may be carried out in a similar manner as described above for the preceding cycle. This is illustrated in Figure 2B, where the numbers (201), (202), (204a-d), (205a-c) and (206a-d) refer to characteristics similar to the characteristics mentioned by the numbers (101), ( 102), (104a-d), (105a-c) and (106a-d) in Figure 1B.

[00152] It should be noted that all pre-hydrolyzate and hydrolyzate solutions in the above examples are suitably aqueous hydrolyzate solutions, respectively aqueous pre-hydrolyzate solutions.

Example 2: Hydrolysis of wood chips in a continuous operation Experimental Setup

[00153] In this laboratory scale example on a vertical plate, 7 tubular reactors made of transparent PVC were mounted in a row, the reactors having a height of 0.53m and a diameter of 0.053m. Each reactor was equipped with a glass filter plate, of pore size 0, at the bottom and top (removable at both ends, to allow filling with wood chips and emptying of lignin particles). Both the bottom and the top of each reactor had a liquid-tight closure screwed onto both ends, said closure having an opening (central) to permit the feeding of liquids into the reactor or the draining or pumping of liquids out of the reactor. with a diameter of 1.58 mm. All reactors were identical.

[00154] Storage tanks were present for: fresh 37% hydrochloric acid solution, tridecane displacement fluid, fresh 41-42% HCl solution (cooled to 0°C). Also present was a tank for receiving a mixture of both used displacement fluid and pre-hydrolyzate, as well as a tank for receiving a mixture of both used displacement fluid and hydrolyzate. All tanks had an open vent so there was no pressure build-up.

[00155] Connected to each reactor were two 10-port selector valves, operated by an electric motor: one with the selector valve inlet connected to the outlet at the bottom of the reactor, one with the selector valve inlet connected to the outlet at the top of the reactor. . Between the selector valve inlet and the reactor outlet was a section of transparent tube (PTFE material, diameter about 1.58 mm, length varying for different reactors, by about 10 cm). Mounted on each tube between the reactor outlet (top and bottom) and the selector valve was an optical sensor. The sensor was a combination of a yellow LED on one side of a 1.58 mm quartz tube (connected to the PTFE tube) and a light detector on the other side. The electronic output of the sensor was connected via a computer to one of the five pumps.

[00156] Selector valve outputs were connected to the inlets (top and bottom) of the neighboring reactors (two), and with the storage tanks (4). The outlet connection tube was of the same material and diameter as the inlets.

[00157] Five pumps were present: one for pumping fresh 37% acid at start-up (flood fill), one for pumping 37% hydrochloric acid during the process from a storage tank, one for pumping 42% hydrochloric acid % from a storage tank, one for displacement fluid to be used between pre- and main hydrolysis, one for displacement fluid after main hydrolysis. The pumps were connected to pipes, both at the top inlet and the bottom inlet.

Materials

[00158] - Rubber tree shavings. Wood chips size: about 50% were 8-16 mm in size, about 50% were 16-45 mm in size. The shavings had a moisture content of about 5%. The contents of the reactors filled with wood chips had an apparent density of about 260 kg/m3.

[00159] - Hydrochloric acid of a concentration of about 37% - Hydrochloric acid of a concentration of 41-42%, as made in-situ by a conventional method.

[00160] - Tridecane as a non-aqueous displacement fluid.

Procedure

[00161] At the beginning of the experiment, all reactors were empty, clean and hydrochloric acid and displacement fluid solutions were present in sufficient quantities in the storage tanks. Then, all reactors were filled with approximately 300 g of the wood chips, the sieve locations and closures were placed in place and the piping connected.

[00162] The system was operated along with the schematic as shown in Table 1, which shows what is inside each reactor and when. Here, the abbreviations have the following meanings: R1, R2, .... R6, R7 as column headers: reactor 1, reactor 2, ... reactor 6, reactor 7.

[00163] In the Table: N without operation FF flooding S stationary FP1 fresh buffer of 37% hydrochloric acid DF1 displacement fluid to displace pre-hydrolyzed with 37% hydrochloric acid FP2 fresh buffer of 42% hydrochloric acid DF2 displacement fluid to displace hydrolyzate with 42% hydrochloric acid R1 flow coming from reactor 1 to reactor 2 R2 flow coming from reactor 2 to reactor 3 R3 flow coming from reactor 3 to reactor 4; and so on.

[00164] FIN reaction completed, removing reactor for lignin discharge.

[00165] Each row in this table is designed to last for about 6 hours.

[00166] For this experiment, for an average amount of biomass of 300 g, a theoretical amount of fresh 37% hydrochloric acid and fresh 42% hydrochloric acid required was calculated. The acid was pumped at a fixed pump speed for the time required to pump in (about) the calculated amount of acid. When it was determined that the correct amount of acid was pumped in, the pump was stopped. Next, displacement fluid (DF1 after FP1, and DF2 after FP2) was pumped into the reactor from the top.

[00167] The time allowed for DF1 and DF2 to be pumped was 6 hours. As follows, the sensors at the bottom of each reactor were triggered before this: after about 2-3 hours, to change from dark colored (pre)hydrolyzate to clear DF liquid. The sensor trip led to the stop of the pump pumping DF liquid. The next stage was only started after the end of the 6-hour time frame.

[00168] The 16-hour pre-hydrolysis was completed in: 1 hour of filling to flooding, 2 hours of fresh buffer in the R+1 reactor, 6 hours of displacement fluid in the R+1 reactor, 1 hour of waiting (at measure R-1 fills to flooding), 2 hours of fresh buffer in this reactor, 6 hours of travel entering this reactor. The flow of acids was controlled by timers. Ideally, the pump should be running for the full phase time, as this keeps the flow in the reactors stable and thus the reaction stable, but this has not yet been achieved. The displacement fluid flow was controlled by optical sensors.

In practice:

[00169] Cycle 1 at t = 0 hours: for the first reaction cycle, reactor 1 was filled to flooding from the bottom in about 30 minutes with fresh 37% acid. The system then remained inactive for 8 hours, as the hydrolyzate needed to accumulate enough color at startup for the required color difference of the optical sensor. At the end of this period (t=8 hours) reactor 2 was flooded from the bottom with fresh 37% acid.

[00170] Next, (t=8.5 hours, starting cycle 2) fresh 37% hydrochloric acid solution was fed to the top of reactor 1, pushing out the pre-hydrolyzate obtained at the bottom of reactor 1, which was fed to the top of reactor 2. At the bottom outlet of reactor 2, prehydrolyzate was collected. By doing so, the reactor remains completely filled with biomass to be hydrolyzed and liquid solution, without any free space or vacuum. The prehydrolyzate was collected in a storage tank.

[00171] Subsequently (t = 16 hours) displacement fluid (DF1) was pumped into the top of reactor 1, which DF1 pushed out pre-hydrolyzate from the bottom of reactor 1. This step was scheduled to last 8 hours, but the pump was stopped when the sensor at the bottom of R1 sensed the step change from pre-hydrolyzate (dark) to displacement fluid (light due to its immiscibility with HCl/pre-hydrolyzate).

[00172] Reactor 3 was now flooded while reactor 2 remained stationary for 30 mins, after which fresh 37% hydrochloric acid was at the top of reactor 2, followed by displacement fluid DF1.

[00173] Reactor 1 has now been finished with pre-hydrolysis and DF1, and has entered the main hydrolysis stage. For this, 42% hydrochloric acid (FP2) was added to the bottom of reactor 1 for about 16 hours, which expelled the displacement fluid at the top of reactor 1.

[00174] The main hydrolyzate was, in this experiment, collected together with the displacement fluid that pushed it out (DF2) and collected in a tank initially (after which manual separation by the separation funnel of the two immiscible phases was conducted ). Table 1: Sequence of activities in reactors 1 to 7. Moment A in Table 1 (time = T + 3 hours)

[00175] At the exit at the bottom of reactor R1, the sensor “felt” a change in color of the flow, changing from FP2 (very dark to almost black color) to DF2 (light) and sent a signal to the computer that triggered the start of the pump to DF2 in order to stop pumping in DF2. After this, reactor R1 was emptied. Moment B in Table 1 (time = T + 2 hours)

[00176] At the outlet at the bottom of reactor R4, the sensor “felt” a change in color of the flow, changing from FP1 (very dark color to almost black) to DF1 (light) and sent a signal to stop the pump that pumps in DF1 . After this, liquid R3 was pumped from the bottom and DF1 was released at the top. Input Mass Flows Summary

[00177] Table 2 presents the mass flows in the system in this experiment. In reactor 7, during flow of fresh 42% acid, the pump failed. Table 2: Mass flows in experiment.

Sensor Activity Results

[00178] Part of the results, for example on lignin, and hydrolysis efficiency are given in Table 2.

[00179] Additional results on the hydrolysates are presented in Table 3. Although for lignin the amount per reactor is measured, the liquid hydrolysates from the various reactors were collected together (hydrolyzate and pre-hydrolyzate separately). Hydrolysates were, before analysis into monomers, subjected to a second hydrolysis, which hydrolyzed the oligomers obtained in each of the pre- and main hydrolyzate. Table 3: Analysis of hydrolysates obtained

[00180] Regarding the amount mentioned as “lost” in Table 3: this refers to the hydrolyzate sugars that are still present in the liquid that is retained in the lignin particles that are obtained from the reactors (the lignin shavings are still wet) as well as any potential (hemi-) cellulose that has not been hydrolyzed.

Conclusion

[00181] When ligno-cellulosic biomass (in the form of wood chips) was subjected to the process of the present invention in this experiment, it produced two products: an aqueous pre-hydrolyzate rich in xylose and mannose (and their oligomers) and an aqueous hydrolyzate rich in glucose (and oligomers), close to lignin.

[00182] Additionally, it was demonstrated that this process could be operated in a continuous mode, in the sense that one reactor was emptied of lignin (and could be filled with fresh wood chips) while the other reactors continued to operate, while also a Minimum pumps and storage tanks are required.

[00183] The use of a non-aqueous displacement liquid ensured the separation of hemicellulose hydrolyzate and cellulose hydrolyzate to a large extent and contributed to a stable state, as well as providing a driving force for the sequential reactions. At the same time, it also facilitated the control of the various reactions without the danger of diluting the acids necessary for the hydrolysis steps.

[00184] Further, the sensors at the bottom of each reactor being triggered earlier than the authorized 6 hours (after about 2-3 hours) by the change from dark-colored to light DF (pre)hydrolyzed liquids passing through the sensor demonstrated that process control in the claimed process was possible with non-invasive sensors.

Claims (15)

1. Process for converting a solid material (201) containing hemicellulose, cellulose and lignin, wherein the process comprises the following steps: (1) hydrolyzing, at a temperature equal to or less than 40°C, preferably equal to or below 30°C, at least part of the hemicellulose of the solid material (201) by contacting the solid material (201) with a first aqueous hydrochloric acid solution (104a), which first aqueous hydrochloric acid solution (104a) has a concentration of hydrochloric acid in the range of equal to or greater than 15.0% by weight to less than 40.0% by weight, based on the amount by weight of water and hydrochloric acid in such first aqueous hydrochloric acid solution (104a), producing a remaining solid material (201) and a first aqueous solution of hydrolyzate product (104b); (111) hydrolyze, at a temperature equal to or less than 40°C, preferably equal to or less than 30°C, at least part of the cellulose of the remaining solid material (201) by replacing the non-aqueous displacement fluid with a second aqueous hydrochloric acid solution (105a), which second aqueous hydrochloric acid solution (105a) has a hydrochloric acid concentration in the range of equal to or greater than 40.0% by weight to equal to or less than 51.0% by weight by weight, based on the amount by weight of water and hydrochloric acid in such second aqueous hydrochloric acid solution (105a), producing a residue and a second aqueous solution of hydrolyzate product (105b); characterized by the fact that after step (i) and before step (iii) there is a step (ii) of displacing the aqueous solution from the remaining solid material (201) with a non-aqueous displacement fluid (106b). 2. Process according to claim 1, characterized by the fact that it further comprises an additional step (iv) comprising displacing the aqueous solution from the residue with additional non-aqueous displacement fluid (106b). 3. Process according to claim 1 or 2, characterized in that the non-aqueous displacement fluid (106b) comprises or consists of an inert gas or an inert liquid, preferably hydrophobic. 4. Process according to any one of claims 1 to 3, characterized by the fact that the non-aqueous displacement fluid (106b) has a boiling temperature at 0.1 MegaPascal equal to or greater than 80°C. 5. Process according to any one of claims 1 to 4, characterized by the fact that the non-aqueous displacement fluid (106b) has a viscosity at 20 ° C equal to or less than 0.005 Pa^s (5 centipoise (cP )). 6. Process according to any one of claims 1 to 5, characterized in that the non-aqueous displacement fluid (106b) comprises or consists of one or more alkanes chosen from the group consisting of cyclic hexane, normal hexane, iso -hexane and other hexanes, normal heptane, isoheptane and other heptanes, normal octane, iso-octane and other octanes, normal nonane, iso-nonane and other nonanes, normal decane, iso-decane and other decanes, normal undecane, iso -undecane and other undecanes, normal dodecane, iso-dodecane and other dodecanes, normal tridecane, iso-tridecane and other tridecanes, normal tetradecane, iso-tetradecane and other tetradecanes, normal pentadecane, iso-pentadecane and other pentadecanes, normal hexadecane, iso -hexadecane and other hexadecanes. 7. Process according to any one of claims 1 to 6, characterized in that non-aqueous displacement fluid (106b) is recovered from step (iii), optionally stored in a displacement fluid storage container (103). displacement, and recycled to step (ii). 8. Process according to any one of claims 1 to 7, characterized in that the process is carried out in a reactor or in a plurality of reactors (R1-R6). 9. Process according to any one of claims 1 to 8, characterized by the fact that the process is carried out in a plurality of reactors (R1-R6), connected in series, ranging from equal to or greater than 2 to equal at or below 16 reactors. 10. Process according to any one of claims 1 to 9, characterized by the fact that the solid material (201) is residing in a stationary phase within a reactor and in which the solid material (201) is brought into contact with a mobile phase moving through such a reactor, which mobile phase includes: - a zone comprising one or more portions of first aqueous hydrochloric acid solution (104a); - a zone comprising one or more portions of a liquid non-aqueous displacement fluid (106b); and - a zone comprising one or more portions of second aqueous hydrochloric acid solution (105a). 11. Process according to claim 10, characterized by the fact that the mobile phase is an intermittent, semi-continuous or continuous mobile phase. 12. Process according to any one of claims 1 to 11, characterized by the fact that - the solid material (201) containing hemicellulose, cellulose and lignin is residing in a stationary phase within a reactor, and is brought into contact in step (i) with one or more zones of a mobile phase moving through such a reactor, including a zone comprising one or more portions of first aqueous hydrochloric acid solution (104a), to produce a first aqueous solution of hydrolyzate product ( 104b) and pre-hydrolyzed solid material (201); and - the aqueous solution is subsequently displaced from the remaining solid material (201) with a non-aqueous displacement fluid (106b), by contacting such remaining solid material (201) in step (ii) with a subsequent zone of mobile phase moving through such a reactor, the subsequent zone of which comprises one or more portions of a liquid non-aqueous displacement fluid (106b); and - the non-aqueous displacement fluid (106b) is subsequently displaced from the remaining solid material (201) with a second aqueous hydrochloric acid solution (105a), by contacting the remaining solid material (201) in step (iii) with one or more subsequent zones of mobile phase moving through such a reactor, including a zone comprising one or more portions of a second aqueous solution of hydrochloric acid (105a), to produce a second aqueous solution of hydrolyzate product (105b) and a residue; and - optionally the aqueous solution is subsequently displaced from the residue with additional non-aqueous displacement fluid (106b), by contacting such residue in an optional step (iv) with a subsequent zone of mobile phase moving through such reactor , the subsequent zone of which comprises one or more additional portions of additional liquid non-aqueous displacement fluid (106b). 13. Process according to any one of claims 1 to 12, characterized by the fact that the process is carried out in a reactor sequence of two or more reactors, in which, during steps (i), (ii), (iii) , solid material (201) is residing stationary within each reactor, while the first aqueous hydrochloric acid solution (104a) and/or the non-aqueous displacement fluid (106b) and/or the second aqueous hydrochloric acid solution (105a ) is/are passed, preferably in a continuous or semi-continuous manner, from one reactor to another reactor. 14. Process according to any one of claims 1 to 13, characterized by the fact that the process is carried out in a plurality of reactors (R1-R6) in a sequence of cycles, wherein within each cycle: - at least one part of the hemicellulose of a solid material (201), containing hemicellulose, cellulose and lignin, is hydrolyzed in a first reactor sequence of “x” reactors FR1 to FRx, in which fresh solid material (201) is introduced into reactor FR1 and each subsequent reactor FR2 to FRx contains solid material (201), partially pre-hydrolyzed; and wherein one or more portions of first aqueous hydrochloric acid solution (104a), preferably fresh, are introduced into the last FRx reactor by pushing forward a first column of liquid, said first column of liquid containing previous portions of first aqueous solution of hydrochloric acid (104a). hydrochloric acid (104a), in a countercurrent direction from reactor FRx to reactor FR1; producing pre-hydrolyzed solid material (201) residing in FRx reactor and a first aqueous hydrolyzate product solution (104b) containing hydrochloric acid residing in FR1 reactor, thereafter the first aqueous hydrolyzate product solution (104b) containing hydrochloric acid is recovered from the FR1 reactor and any aqueous solution(s) is/are displaced from the pre-hydrolyzed solid material (201) with an, suitably first, non-aqueous displacement fluid (106b ) in FRx reactor; - at least a portion of the cellulose of a pre-hydrolyzed solid material (201) is hydrolyzed in a second reactor sequence of “y” reactors SR1 to SRy, wherein fresh pre-hydrolyzed solid material (201) is residing in reactor SR1 and each subsequent reactor SR2 to SRy contains pre-hydrolyzed, partially hydrolyzed solid material; and wherein one or more portions of second aqueous hydrochloric acid solution (105a), preferably fresh, are introduced into the last SRy reactor by pushing forward a second column of liquid, said second column of liquid containing previous portions of second aqueous solution of hydrochloric acid (105a), in a countercurrent direction from reactor SRy to reactor SR1; producing a residue residing in reactor SRy and a second aqueous solution of hydrolyzate product (105b) containing hydrochloric acid residing in reactor SR1; thereafter the second hydrolyzate product aqueous solution (105b) containing hydrochloric acid is recovered from reactor SR1; and optionally any aqueous solution(s) is/are displaced from the residue with an, suitably second, non-aqueous displacement fluid (106b) in SRy reactor and then discharged to from the SRy reactor; after that - respective reactors FR1 to FRx-1 switch to the respective reactor position FR2 to FRx, - respective reactor FRx switches to the respective reactor position SR1, - respective reactors SR1 to SRy-1 switch to the respective reactor position SR2 a SRy, and - respective reactor SRy switches to the respective reactor position FR1. 15. Process according to any one of claims 1 to 14, characterized by the fact that the number of reactors in which step (iii) is carried out is 1.5 to 3 times the number of reactors in which step (i) is realized.