WO2014164557A1

WO2014164557A1 - Continuous counter current hydrolysis of polycarbohydrate

Info

Publication number: WO2014164557A1
Application number: PCT/US2014/022795
Authority: WO
Inventors: Ed LEHRBURGER; Richard Wingerson; Chim Yong Chin
Original assignee: Purevision Technology, Llc
Priority date: 2013-03-10
Filing date: 2014-03-10
Publication date: 2014-10-09

Abstract

The present invention provides methods for producing monomeric and oligomeric carbohydrate from solids biomass using a pressurized reaction vessel. In particular, methods of the invention utilize solvent and acid hydrolysis in continuous counter flow to the solids biomass, and in-situ comminuting of the solids biomass during hydrolysis.

Description

CONTINUOUS COUNTER CURRENT HYDROLYSIS OF

POLYCARBOHYDRATE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is continuation-in-part of U.S. Patent Application No.

14/088,929, filed November 25, 2013, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to the rapid hydrolysis and fluidization of cellulosic materials. In particular, the present invention relates to using an extruder/conveyor to carry out continuous counter current processing of organic compositions that include cellulose and other lignocellulosic materials to produce fluidized carbohydrates and other intermediates used to manufacture industrial fuels and chemicals and consumer products.

BACKGROUND OF THE INVENTION

[0003] Many conventional processes use enzymes to hydrolyze cellulose to monomeric carbohydrates. These processes generally require that natural cellulose source materials receive extensive pretreatment to remove accompanying materials having the potential for interference with enzymatic hydrolysis and further downstream processing. Furthermore, enzymatic hydrolysis typically requires anywhere from 48 to 168 hours for completion.

[0004] Cellulose is a glucose polymer that is often found in the amorphous form and in the microcrystalline form. To date no commercial scale process exists for non-enzymatic rapid hydrolysis of cellulose that uses an extruder/conveyor as the continuous reactor. Typically, conventional, non-enzymatic, cellulose hydrolysis processes are characterized by slow hydrolysis rates, dilute product concentration, expensive acid recovery, and/or extensive sugar conversion into undesirable non sugars, e.g., furfurals and organic acids. Potential commercial applications for products derived from renewable sources have increased interest in rapid hydrolysis of cellulosic materials to yield fluidized products including simple monomeric sugars, oligomeric sugars, lignin, and other intermediate products such as furfural,

hydroxymethylfurfural, levulinic acid, formic acid and others ("intermediate products"). SUMMARY OF THE INVENTION

[0005] Some aspects of the invention provide methods for rapidly producing fluidized compositions comprising carbohydrates (such as pentose and hexose monosaccharides) from a biomass feedstock comprising polycarbohydrate such as cellulose. Typically, the fluidized carbohydrate comprises monomeric carbohydrate, oligomeric carbohydrate, or a mixture thereof. It should be appreciated that while the term "oligomeric carbohydrate" can be encompassed by the term "polycarbohydrate", for the purposes of the present invention the term "oligomeric carbohydrate" refers to carbohydrate that has a smaller unit than the starting material, i.e., biomass feedstock polycarbohydrate. Thus, the term "oligomeric carbohydrate" refers to polycarbohydrate that has been at least partially hydrolyzed.

[0006] Methods of the invention typically include using an extruder or conveyor reaction vessel ("reaction vessel") having a proximal end and a distal end. The reaction vessel can include at least one or more inlet ports at or near the proximal end for injecting the solid cellulosic material. The reaction vessel can also include one or more inlet ports at or near the distal end for injection of a hydrolysis fluid that flows counter current to the direction of the biomass feedstock movement within the reaction vessel. The hydrolysis fluid comprises an acid and a fluid medium, e.g., reagent. Typically the fluid medium comprises water and an organic solvent. The amount of water present in the initial hydrolysis fluid can vary depending on a variety of factors including, but not limited to, the rate of reaction desired, the acid used, the reaction temperature, etc. The reaction vessel can also include an inlet port at or near the distal end for injection of water and/or solvent, free of acid, for rinsing any residual solids prior to solids discharge. Typically, however, the total amount of water in counter flow is at least about 5% by volume, often at least about 15%, most often at least about 30%. Methods of the invention include adding the biomass feedstock (e.g., cellulosic material) to the reaction vessel via one or more inlet ports at or near the proximal end and transporting the biomass feedstock to the distal end of the reaction vessel as the hydrolysis fluid is introduced in a counter current fashion relative to the overall direction of the solid biomass feedstock flow.

[0007] As the biomass feedstock moves from the proximal end to the distal end of the reaction vessel, the hydrolysis fluid is added to the reaction vessel (e.g., injected into the reaction vessel) through one or more inlet ports near or at the distal end and flows from the distal end to the proximal end of the reaction vessel. Additional fluid injection ports may be present along the length of the reactor and may inject similar hydrolysis fluid or additional acid medium.

Accordingly, the biomass feedstock and the hydrolysis fluid travel in an opposite direction from one another. Typically, methods of the invention comprise continuous counter current flow of hydrolysis fluid and the biomass feedstock. Sufficient reaction conditions are maintained within the reaction vessel to hydrolyze polycarbohydrates (e.g., cellulosic material) into fluidized monomeric carbohydrate, oligomeric carbohydrate, and/or other targeted intermediates. As used herein, the term "continuous" includes intermittent stop and go flow as long as any one flow stoppage is no more than half of the average mean residence time of the solids, typically no more than 20 minutes, and often no more than 10 minutes. Pseudo steady-state or simulated steady- state operating conditions and other such flow conditions are derivatives of the "continuous" art described herein.

[0008] Typically, the fluidized carbohydrates are withdrawn from the reaction vessel through one or more outlet ports that are located on or near the proximal end of the reaction vessel. Any remaining product of the biomass feedstock (e.g., cellulosic material, ash, etc.) is removed from the reaction vessel through an outlet port that is located on or near the distal end of the reaction vessel. In some instances, prior to removing the residual solid, it can be rinsed or washed with water and/or other solvent.

[0009] In some aspects of the invention less than 50%, typically less than 25%, often less than 15%, and most often less than 10% of the cellulose in the biomass feedstock is present in the fluidized composition. Without being bound by any theory, it is believed that this is due to conversion or hydrolysis of cellulose to oligomeric (e.g., about 25 or less, typically about 15 or less, often 10 or less, and most often 5 or less carbohydrate units) and/or monomeric

carbohydrates.

DETAILED DESCRIPTION OF THE INVENTION

[0010] Some aspects of the invention involve using a counter current flow process for rapidly hydro lyzing polycarbohydrates (e.g., cellulose, hemicelluloses, etc.) to produce fluidized carbohydrates or other targeted intermediates. The term "fluidized" refers to having fluid-like flow characteristics and can be a fluidized carbohydrate (i.e., in solution), slurry (e.g., a mixture of fines and solution), etc. Methods of the invention can be used to hydrolyze hemicellulose and/or cellulose from any cellulosic material. As used herein, the term cellulosic material refers to any organic composition containing cellulose including natural materials, partially processed materials, and waste or recycled materials.

[0011] Natural materials comprising cellulose typically are referred to as "biomass" or

"biomass feedstocks." Exemplary biomass feedstocks include, but are not limited to, wood, paper, agricultural residues, herbaceous crops (e.g., corn stover, corncobs, wheat straw, triticale straw, empty fruit bunches, bagasse, rice straw; dedicated energy crops such as miscanthus, switch grass, poplar, etc.), and municipal and industrial solid wastes (e.g., MSW, packaging, recycled pulp, anaerobic digestate, railroad ties, etc.). Biomass feedstock can be processed or treated to remove thrash, de -buffered, size reduced, sorted, partially extracted or otherwise processed as an individual method or a combination of methods thereof, prior to the methods of the invention. Biomass feedstock can also be a mixture of one or more such materials. These biomass feedstocks primarily consist of cellulose, hemicellulose, and lignin bound together in a complex gel structure along with small quantities of extractives, pectins, proteins, and ash ("biomass feedstocks"). Due to the complex chemical structure of the biomass feedstocks, microorganisms and enzymes cannot effectively rapidly attack the cellulose without prior treatment because the cellulose is highly inaccessible to enzymes or bacteria. This

inaccessibility is illustrated by the inability of cattle to digest wood with its high lignin content even though they can digest cellulose from such material as grass. Additionally, tightly packed cellulose, with high crystallinity, limits cellulose accessibility and further reduces enzymatic hydrolysis rate. Thus, successful commercial use of biomass feedstocks is sometimes believed to depend on the separation of highly digestible cellulose from other constituents. This invention overcomes the problem of inaccessibility.

[0012] Accordingly, methods of the invention typically utilize the biomass feedstock that is continuously processed (including a process that utilizes intermittent stoppage as described above) to rapidly produce cellulose, fluidized carbohydrates and/or other targeted intermediates. There are many methods and apparatuses known to one skilled in the art for producing cellulose, fluidized carbohydrates and/or other target intermediates from biomass feedstocks including methods and apparatuses disclosed in commonly assigned U.S. Patent Nos. 6,419,788;

6,620,292; 7,600,707; 7,717,364; and 8,136,747, all of which are incorporated herein by reference in their entirety. Typically, the initial processing of biomass feedstock provides a solution or slurry of its components, e.g., (1) oligomeric components, such as lignocellulose, cellulose, lignoxylan, lignin, hemicellulose, xylan and others, (2) monomeric sugars such as glucose, xylose, arabinose and others, (3) lignin-derived polyphenols and phenolics including phenol, vanillin, p-coumaryl alcohols, coniferyl alcohol, sinapyl alcohol and others, (4) organic acids such as acetic acid, formic acid and others, and (5) dehydration products such as hydroxymethylfurfural, furfural, levulinic acid, and others. Typically, methods of the invention utilize cellulosic materials that comprise 25% or less of lignin, often 20% or less of lignin, and sometimes 15% or less of lignin.

[0013] As discussed above, methods of the invention include using a counter current process in which the biomass feedstock and the counter flow of hydrolysis fluid are continuously transported in an opposite direction while maintaining reaction conditions sufficient to rapidly produce fluidized carbohydrates (e.g., oligoglucan, oligoxylan, glucose and xylose) from the biomass feedstocks. Suitable reaction vessels for such a counter current process are also disclosed in the commonly assigned U.S. Patents that are incorporated by reference and disclosed above.

[0014] Without being bound by any theory, it is believed that agitation and relatively high hydrolysis fluid (e.g., liquid) velocities improve yields of fractionation and hydrolysis reactions for biomass feedstock and related solids at high temperature where product degradation may be significant. Accordingly, the mass flow rate of the hydrolysis fluid relative to the biomass feedstock is typically more than twice the dry solids feedrate, often about three times the dry solids feedrate, and more often about four times the dry solids feedrate. It is also believed that agitation and high fluid velocity relative to the biomass feedstock results in the reduction of boundary layers effects, and subsequently improvement of the diffusion rate of products from the biomass feedstock surface into the fluid medium. This in turn is believed to improve the diffusion of the hydrolysis fluid (e.g., water and acid) onto the bulk solids surface, reduce the residence time of the products at the reaction temperature (by rapid removal of the products from reactor conditions) and thus reduce the occurrence of further degradation of products thereby improving overall yield of the soluble carbohydrates. Thus, in some embodiments, the biomass feedstock is contacted with the hydrolysis fluid for about 60 min or less, typically about 45 min or less, and often about 30 min or less. Methods of the invention yield at least about 40%, typically at least about 75%, often at least about 90%, and more often at least about 95% of the theoretical yield of fluidized carbohydrates from the biomass feedstock. One skilled in the art can readily determine the theoretical yield of soluble carbohydrate by first determining the amount of cellulose and hemicellulose present in the biomass feedstock. Such methods are well known to one skilled in the art.

[0015] In some embodiments, at least a portion of the hydrolysis fluid is recovered and recycled, thereby reducing the costs to produce carbohydrates and/or other intermediates and the amount and cost of chemical disposal. One of the disadvantages of the high fluid velocity is that it also results in substantial dilution of the soluble carbohydrates in the fluid stream. Recycling of the fluid stream back into the reaction vessel without recovering fluidized carbohydrates would further expose fluidized carbohydrates to the reaction conditions resulting in the loss of the advantage of short residence time, and potentially degrade produced fluidized carbohydrates.

[0016] In some aspects of the invention, at least a portion of the hydrolysis fluid is replaced with a fresh batch of hydrolysis fluid. In some instances, recycling of the relatively carbohydrate-free portion of the hydrolysis fluid, typically the organic solvent, results in a hydrolysis fluid that has (1) similar or better volumetric bulk, and/or (2) sufficiently similar or better chemical properties (e.g., solvation and acidity) relative to the desired reaction and by- reactions. Furthermore, the resulting sugar-rich fluid remaining from the hydrolysis fluid recycle has substantially concentrated sugar in a mostly water-rich fluid. In some embodiments, the hydrolysis fluid is amenable to a quick, efficient and simple separation and recycling.

[0017] The process of dilute acid hydrolysis of biomass at elevated temperature (and pressure) has been investigated extensively for many years. One of the problems encountered with conventional non-enzymatic dilute acid hydrolysis of polycarbohydrate is that conditions that lead to hydrolysis of polycarbohydrate also lead to further degradation of the carbohydrates (or sugars) formed. Such a problem typically requires a compromise between fluidized carbohydrate yield and concentration of the fluidized carbohydrates produced. One solution to this problem is to include reagent(s) that interfere with and/or emphasize particular steps in the hydro lysis/degradation process. Although acid is seen as a catalyst for hydrolysis (with pH being a useful measure of effectiveness) the structure and properties of different acids can lead to effects that go beyond what can be attributed to pH alone. Other reagents such as solvents can also affect the hydrolysis process by increasing product solubility, reactant accessibility and/or by inhibiting secondary reactions or even by competing with undesirable secondary

reactions. Many variables can be changed to improve the yield of fluidized carbohydrate(s) and other chemicals.

[0018] Continuous counter current processing of biomass feedstock offers several advantages over batch, plug-flow, or percolation processes. Continuous processes are more energy efficient and have smaller footprint than batch processes. Counter current processing increases the relative fluid velocity. A particular feature relevant to biomass feedstock processing is that the solid and fluid fractions can experience different environmental histories since they pass through a sequence of reaction zones in opposite directions. For example, if reaction zones within the reaction vessel are operated so that the solids (i.e., biomass feedstock) experience progressively increasing severity of treatment, then the fluid component carrying the fluidized carbohydrate(s) will experience progressively decreasing severity of treatment. This creates a bias that favors initial hydrolysis of the biomass feedstock while slowing the further degradation of fluidized carbohydrates.

[0019] Some embodiments of continuous, counter current processes and apparatuses are described in the above disclosed commonly assigned U.S. Patents, which have been incorporated by reference. Some embodiments of the invention include changes from the apparatus described in the above-incorporated U.S. Patents. In some instances, the changes include how the "spent solids", i.e., biomass feedstock that have been subjected to the hydrolysis conditions but have not dissolved, are discharged from the reaction vessel. In some cases, the biomass feedstock is almost completely dissolved so that there are not significant solids remaining to form a dynamic plug at the solids discharge end of the reaction vessel. Instead, a settling basin (which can be emptied intermittently) is provided to collect the residual solids at elevated pressure. These residual solids can be added back to the biomass feedstock for a second round of counter current processing, sold as a byproduct or burned to create process steam and power. In some particular embodiments of the continuous, counter current processes and apparatus descried herein include the in situ comminuting of the biomass feedstock at the operating pressure and temperature within the reaction vessel. Typically batch, plug-flow or percolation processes require separate comminuting of the biomass feedstock prior to hydrolysis. The combined comminuting and hydrolysis in the present invention improves overall energy efficiency.

[0020] As stated above, methods of the invention involve non-enzymatic hydrolysis of polycarbohydrates (e.g., cellulosic materials). The hydrolysis fluid comprises a fluid medium (e.g., gas, liquid and/or solvent) and an acid. Typically, the hydrolysis fluid comprises a dilute acid such that the pH of the hydrolysis fluid ranges from pH of no less than 0 to pH of about 6.5, typically pH of about 0.5 to pH of about 3.0. Alternatively, the pH of the hydrolysis fluid is pH of about 6.5 or less, typically pH of about 3 or less, often pH of about 2 or less, and more often pH ranging from pH of about 0 to pH of about 2. As used herein, the term "fluid" refers to a liquid, gas, or a mixture thereof. In many instances, the hydrolysis fluid comprises water and an organic solvent. Suitable organic solvents include, but are not limited to, an alcohol, a ketone, or a mixture thereof. Exemplary alcohols that can be used as a solvent include, but are not limited to, methanol, ethanol, n-butanol, iso-butanol, n-propanol, iso-propanol or a mixture thereof. Exemplary ketones that can be used as a solvent include, but are not limited to, acetone.

[0021] Hydrolysis fluid of the invention also includes an acid. Generally, the nature and the amount of acid used is such that the resulting (i.e., initial) pH of the hydrolysis fluid falls within the ranges disclosed above. Suitable acids for methods of the invention include, but are not limited to, a carboxylic acid, phosphoric acid, phosphorous acid, nitric acid, sulfuric acid, sulfurous acid, hydrochloric acid, carbonic acid, and a mixture thereof. The carboxylic acid can be a monocarboxylic acid or a dicarboxylic acid. Exemplary carboxylic acids that are useful for methods of the invention include, but are not limited to, maleic acid, acetic acid, propionic acid, formic acid, levulinic acid, or a combination thereof.

[0022] In some embodiments, the initial temperature of the hydrolysis fluid that is introduced into the reaction vessel is at least about 160 °C, typically at least about 180 °C, and often at least about 200 °C. It should be appreciated that in order to maintain the hydrolysis fluid at that temperature in a liquid form requires high pressure. Thus, the hydrolysis fluid is often injected into the reaction vessel under high pressure such that the pressure within the reaction vessel exceeds the maximum saturation vapor pressure of the hydrolysis fluid.

[0023] As discussed above, the material used in methods of the invention sometimes comprises a biomass feedstock that has been processed or pretreated prior to being subjected to the hydrolysis conditions of the present invention. In some embodiments, the biomass feedstock comprises cellulose obtained from a lignocellulosic biomass; or substantially processed materials including but not limited to linen, newspaper, food waste, anaerobic digestate and manure.

[0024] Another aspect of the invention provides methods for producing fluidized carbohydrates from a biomass feedstock using a counter current reaction vessel. The counter current reaction vessel comprises a proximal end comprising at least an inlet port and at least an outlet port, and a distal end comprising at least an inlet port and typically, but not necessarily, an outlet port. Such method typically includes:

introducing the biomass feedstock into the reaction vessel through the proximal end inlet port and transporting the biomass feedstock to the distal end of the reaction vessel; and

introducing a hydrolysis fluid into the reaction vessel through the distal end inlet port and flowing the counter flow reagent towards the proximal end outlet port of the reaction vessel under conditions sufficient to contact the biomass feedstock with the hydrolysis fluid within the reaction vessel to rapidly produce soluble carbohydrates from the biomass feedstock.

[0025] In some embodiments, the continuous, counter current reaction vessel is a screw extruder. In some instances, the screw extruder is a single screw extruder. Yet in other instances, the screw extruder is a multi-screw extruder. Still in other instances, the screw extruder is a twin-screw extruder. And still in other instance, the twin-screw extruder is a co- rotating twin-screw extruder. In other embodiments, the continuous, counter current reaction vessel is a screw conveyor. In some instances, the screw conveyor is a single screw conveyor. Yet in other instances, the screw conveyor is a multi-screw conveyor. Still in other instances, the screw conveyor is a twin-screw conveyor.

[0026] Yet in other embodiments, at least 40% of the biomass feedstock is hydrolyzed to fluidized carbohydrates within 60 minutes. Still in other embodiments, at least 75% of the biomass feedstock is hydrolyzed to fluidized carbohydrates within 60 minutes. Yet still in other embodiments, at least 90%> of the biomass feedstock is hydrolyzed to fluidized carbohydrates within 60 minutes. [0027] Some aspects of the invention utilize weakly acidified water as the primary hydrolysis fluid. In some embodiments, the hydrolysis fluid comprises acetone (typically at least 50% by weight, often at least 70% by weight, and more often at least 80%> by weight). Acetone offers several advantages including, but not limited to, (1) cost and availability that contributes to process economics, (2) miscibility with water in all proportions that avoids some potential diffusion problems, (3) lower viscosity than water that improves diffusion of acid into biomass fibers and improves diffusion of sugars out of the fibers, (4) solvent for some lignin degradation products that enhances lignin mobilization and inhibits formation of refractory condensates, (5) weak chemical association with monomeric carbohydrate that slows further degradation, (6) a boiling point of 56 °C that facilitates separation, recovery, and recycle, (7) a low specific heat and low heat of vaporization that contribute to energy efficiency for the process, and (8) acetone softens and swells cellulose increasing accessibility to acid hydrolysis. All of these advantages are, of course, in addition to minimizing the residence time of mobilized products in the reactor.

[0028] In some particular embodiments, maleic acid (e.g., 0.025 molar at pH 2.2) can be used to control the pH of the hydrolysis fluid. Maleic acid can have a positive effect on product yield. However, it should be appreciated that many other organic and mineral acids, such as those disclosed above, can also be used. Acetic acid is often used in some instances because it is a biorefmery byproduct. Sulfuric acid is used in other instances for its cost and

availability. Sulfurous acid or hydrochloric acid can be used because their volatility allows ease of separation and recycling. Phosphoric or nitric acids can also be used because of their potential value as nutrients in downstream processing or waste disposal. Other suitable acids include, but are not limited to, propionic acid, formic acid, levulinic acid, phosphorous acid, carbonic acid, and mixtures thereof. One skilled in the art having read the present disclosure will understand how to make a suitable choice after consideration of various factors relevant to a particular application.

[0029] In some aspects of the invention, a co-rotating twin-screw extruder similar to those commonly used in the food and plastics industries is used. Typically, the length to diameter ratio of such reactor is 48: 1 or more. However, it should be appreciated that the scope of the invention is not limited to such a ratio of length to diameter. It is believed that the twin screws of the reactor serve both to transport solids and to minimize boundary layers and reaction times through continuous, vigorous mixing. Additionally, the reactor allows for in situ physical size reduction and fluid/solid separation. Other apparatuses or even a single-screw extruder or conveyor can be used in methods of the invention. In fact, those skilled in the art having read the present disclosure will note that a variety of reactors can be used in continuous counter current process.

[0030] As an alternative embodiment, a simulated moving bed reactor as described, for example, in the commonly assigned U.S. Patent No. 7,717,364, which is incorporated herein by reference in its entirety, can be used instead of a continuous, counter flow reaction vessel.

[0031] Typically, a counter current flow of biomass feedstock and hydrolysis fluid is employed, and a temperature ramp from about 140 °C to about 240 °C, typically from about 160 °C to 220 °C, more typically from about 180 °C to 210 °C, is established in the direction of biomass feedstock flow. Typically, the biomass feedstock material first encounters rather mild conditions where more fragile components are mobilized, washed quickly from the reaction zone, and then cooled to minimize further reactions. As the biomass feedstock progresses or is transported further down the reaction vessel, it encounters more severe conditions (e.g. higher temperature and more concentrated reagent); more refractory components are mobilized; and the mobilized material is washed into less severe conditions where degradation is minimized.

[0032] Acid hydrolysis is most commonly carried out at temperatures from about 140 °C to about 180 °C in batch, plug-flow or percolation reactors. Higher temperatures can be employed in a continuous, counter flow reactor, compared to batch or plug-flow reactors. It is generally known that the higher temperatures speed reactions by approximately a factor of two for each 10 °C of temperature increase, and this leads to more rapid hydrolysis and increased reactor throughput. Advantage can be taken of this increased throughput to either increase production or to decrease the size and footprint of equipment needed for any particular production, either of which results in improved economics for the process.

[0033] The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. Although the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.

Claims

What is Claimed is:

1. A method for producing a fluidized composition comprising a monomeric carbohydrate, oligomeric carbohydrate, or a mixture thereof from a solid biomass feedstock comprising a polycarbohydrate, said method comprising:

transporting the solid biomass feedstock from at or near a proximal end of an extruder or conveyor reaction vessel to a distal end of the reaction vessel, wherein at least a portion of the solid biomass feedstock is comminuted within the reaction vessel; introducing counter flow of a hydrolysis fluid from at or near the distal end of the

reaction vessel to the proximal end of the reaction vessel under conditions sufficient to provide the fluidized composition comprising monomeric

carbohydrate, oligomeric carbohydrate, or a mixture thereof from the solid biomass feedstock; and

obtaining the fluidized composition at or near the proximal end of the reaction vessel, wherein the initial hydrolysis fluid comprises at least 5% by volume of water, acid and an organic solvent, and wherein the mean residence time of the solid biomass feedstock in the reaction vessel is 60 minutes or less.

2. The method of Claim 1, wherein the initial temperature of the hydrolysis fluid is at least about 140 °C.

3. The method of Claim 2, wherein the pressure within the reaction vessel exceeds the maximum saturation vapor pressure of the hydrolysis fluid and fluidized composition.

4. The method of Claim 1 , wherein water is introduced at or near the distal end of the reaction vessel for rinsing of any residual solid prior to its discharge from the reaction vessel.

5. The method of Claim 1, wherein the polycarbohydrate comprises cellulose, hemicellulose, lignin, or a combination thereof.

6. The method of Claim 5, wherein the biomass feedstock further comprises hemicellulose, lignin, or a combination thereof.

7. The method of Claim 1, wherein the fluidized composition further comprises furfural, hydroxymethylfurfural, levulinic acid, formic acid, acetic acid or a combination thereof.

8. The method of Claim 1, wherein the organic solvent comprises an alcohol, a ketone, or a mixture thereof.

9. The method of Claim 8, wherein the alcohol comprises methanol, ethanol, propanol, butanol, or a mixture thereof.

10. The method of Claim 8, wherein the ketone comprises acetone.

11. The method of Claim 10, wherein the fluidized composition further comprises an acetonated carbohydrate.

12. The method of Claim 1 , wherein the initial pH of the hydrolysis fluid is pH of about 5.5 or less.

13. The method of Claim 1, wherein the initial pH of the hydrolysis fluid ranges from pH of about 1 to pH of about 6.

14. The method of Claim 1, wherein the initial pH of the hydrolysis fluid ranges from pH of about 0 to pH of about 6.5.

15. The method of Claim 1, wherein the acid comprises a carboxylic acid, phosphoric acid, phosphorous acid, nitric acid, sulfuric acid, sulfurous acid, sulfamic acid, sulfonic acid, hydrochloric acid, carbonic acid, or a mixture thereof.

16. The method of Claim 15, wherein the carboxylic acid is a monocarboxylic acid, a dicarboxylic acid, or a combination thereof.

17. The method of Claim 15, wherein the carboxylic acid comprises maleic acid, acetic acid, propionic acid, formic acid, levulinic acid, or a combination thereof.

18. The method of Claim 1 , wherein at least 40% weight of the solid biomass feedstock is obtained as the fluidized composition.

19. The method of Claim 1, wherein at least 90% weight of the solid biomass feedstock is obtained as the fluidized composition.

20. A method for producing a fluidized composition comprising monomeric carbohydrate, oligomeric carbohydrate, or a mixture thereof from a solid biomass feedstock comprising cellulose using a counter current reaction vessel, wherein the counter current reaction vessel comprises:

a proximal end comprising an inlet port and an outlet port, and

a distal end comprising an inlet port;

said method comprising:

introducing the solid biomass feedstock into the reaction vessel through the proximal end inlet port;

transporting the solid biomass feedstock to the distal end of the reaction vessel;

comminuting at least a portion of the solid biomass feedstock within the reaction vessel; and

introducing a hydrolysis fluid into the reaction vessel through the distal end inlet port and flowing the hydrolysis fluid towards the proximal end outlet port of the reaction vessel under conditions sufficient to produce the fluidized composition from the biomass feedstock, wherein the hydrolysis fluid comprises water, acid, and an organic solvent, and wherein the amount of water in the hydrolysis fluid is at least 5% by volume of the hydrolysis fluid.

21. The method of Claim 20, wherein the distal end of the counter current reaction vessels further comprises an outlet port.

22. The method of Claim 20, wherein the counter current reaction vessel is a screw extruder or conveyor.

23. The method of Claim 21, wherein the screw extruder or conveyor is a multi-screw extruder or conveyor.

24. The method of Claim 22, wherein the screw extruder or conveyor is a twin-screw extruder or conveyor.

25. The method of Claim 23, wherein the twin-screw extruder is a co-rotating twin screw extruder.

26. The method of Claim 20, wherein the mean residence time of the solid biomass feedstock within the reaction vessel is about 60 minutes or less.

27. The method of Claim 20, wherein the fluidized composition comprises at least 40% weight of the solid biomass feedstock.

28. The method of Claim 20, wherein the fluidized composition comprises at least 75% by weight of the solid biomass feedstock.

29. The method of Claim 20, wherein the fluidized composition comprises at least 90%) by weight of the solid biomass feedstock.

30. A method for producing a fluidized carbohydrate composition from a solid biomass feedstock comprising cellulose using a counter current reaction vessel, wherein the counter current reaction vessel comprises:

a proximal end comprising an inlet port and an outlet port, and

a distal end comprising an inlet port and an outlet port;

said method comprising:

transporting the introduced solid biomass feedstock to the distal end outlet port of the reaction vessel with a mean residence time of about 60 minutes or less;

comminuting at least a portion of the solid biomass feedstock within the reaction vessel; introducing a hydrolysis fluid into the reaction vessel through the distal end inlet port; and

flowing the hydrolysis fluid towards the proximal end outlet port of the reaction vessel under conditions sufficient to produce the fluidized carbohydrate composition from the solid biomass feedstock, wherein the hydrolysis fluid comprises water, acid, and an organic solvent.