HK1198447B - Method and apparatus for lignocellulose pretreatment using a super-cellulose-solvent and highly volatile solvents - Google Patents

Description

Method and apparatus for pretreating lignocellulose using a hypercellulose solvent and a highly volatile solvent

The application is a divisional application of Chinese invention application with the application date of 2009, 3 and 16, the application number of 200980117175.8, and the invention name of "method and device for pretreating lignocellulose by using super-cellulose solvent and high-volatility solvent".

Cross Reference to Related Applications

This application relies on and claims the benefit of U.S. provisional patent application No. 61/036,813 filed on 3/14/2008, the entire disclosure of which is incorporated herein by reference.

Technical Field

The present invention relates to the field of alternative energy sources and methods of extracting energy from these energy sources. More particularly, the present invention relates to the biodegradation and biochemical degradation of plant material, including lignocellulose, for the production of energy sources for use in human activities.

Background

The production of biological products and biological energy from renewable lignocelluloses faces the depletion of natural resources, particularly fossil fuels, and the atmospheric carbon dioxide (CO) produced thereby₂) Sustainable development of the accumulating human industrial society is important. Moreover, the development of technologies that efficiently convert agricultural and forestry residues into fermentable sugars offers significant potential for benefiting the benefits of the united states nations. Moreover, the production of these second generation biofuels, such as cellulosic ethanol, and third generation biofuels, such as hydrogen and electricity, from renewable lignocellulosic biomass will lead to the necessary bio-industrial revolution to shift from fossil fuel-based economy to sustainable carbohydrate economy. The use of biofuels also provides several benefits, including reducing greenhouse gas emissions, reducing competition with tight food supplies, enhancing rural economic development and improving national energy safety. However, major technical challenges in this area include finding new technologies for energy production and reducing the technical costs of converting biomass (mainly lignocellulose) into desired bio-based industrial products and bio-energy sources.

Lignocellulosic biomass, such as agricultural and forestry residues, municipal and industrial solid wastes, and herbaceous and woody bioenergy plants, is a natural complex composed mainly of three biopolymers: cellulose, hemicellulose and lignin. Depending on its origin, lignocellulose typically contains cellulose (about 35-50wt%), hemicellulose (about 15-35%) and lignin (about 5-30%). Natural cellulose molecules are present in basic cellulose fibrils (fibrils) and are closely related to other structural polysaccharides, such as hemicellulose, lignin and pectin.

Efficient, cost-competitive production of fermentable sugars from recalcitrant biomass remains the biggest hurdle to the biorefinery of cellulosic ethanol. Saccharification of biomass by bioconversion involves two key steps: lignocellulose is pretreated or fractionated (fractionation) followed by enzymatic hydrolysis of the cellulose (and possibly hemicellulose) to produce fermentable sugars. The high processing costs of the conversion process and the thin margin between the cost of the raw material and the price of the sugar are key obstacles to commercialization.

One of the most important technical challenges is to overcome the recalcitrance of natural lignocellulosic materials to allow enzymatic hydrolysis to produce fermentable sugars. Lignocellulose pretreatment is perhaps the most expensive step. One estimates that it will account for about 40% of the total processing cost. In addition, recalcitrance affects the cost of most other operations involving the decomposition of lignocellulose, including the cost of reducing the size of the lignocellulose prior to pretreatment. Pretreatment of lignocellulosic material is thus closely associated with downstream costs including enzymatic hydrolysis rates (enzymatic hydrolysis rates), enzyme loading, hybrid power consumption, product concentration, detoxification if inhibitors are produced, product purification, power generation, the need for waste treatment, and other variables.

The recalcitrance of cellulosic biomass to enzymes is believed to be due to 1) complex linkages (linkages) between several major polysaccharides including cellulose, hemicellulose and lignin, limiting the hydrolytic activity of cellulases, hemicellulases and laccases; and 2) the inherent properties of cellulosic materials, including low substrate accessibility to cellulases, high Degree of Polymerization (DP) and low solubility of the cellulose fragments in water. Pretreatment of lignocellulosic materials is thus considered an important step in increasing the overall product yield (yield) from these materials.

All lignocellulosic treatments can be divided into four broad categories: 1) physical methods, including dry milling (slicing, ball milling and crushing)) Wet milling, irradiation, microwave and expansion agents (e.g., ZnCl)₂) (ii) a 2) Chemical processes involving dilute acids (e.g. dilute H)₂SO₄Rare H₃PO₄Dilute HCl, dilute acetic acid, dilute formic acid/HCl), bases (e.g., NaOH, lime, ammonia, amines), organic solvents (organosolv), oxidizing agents (e.g., O)₃、NO、H₂O₂、NaClO₂) Cellulose solvent (e.g., cadoxen), DMAc/LiCl, and concentrated H₂SO₄(ii) a 3) Physical-chemical methods, including steam explosion, CO with or without catalyst₂Blasting, ammonia fiber blasting or expanding (AFEX), through-flow of hot water (hot water with flow-through), supercritical fluid extraction (e.g., CO₂、CO₂/H₂O、CO₂/SO₂、NH₃、H₂O); and 4) biological methods (e.g., white rot fungi).

Recently, the Biomass Refining application Foundation and Innovation Consortium (CAFI) began the first collaborative project to develop comparative information on the execution of mainstream pre-processing options. The federation concludes: the best pretreatment includes: dilute acid, through-flow pretreatment, ammonia fiber blasting, ammonia recycle infiltration (ARP), and lime pretreatment. In addition, two other possible pretreatments have been intensively studied in europe and canada: with or without SO₂Impregnated steam explosion and organic solvent. Typical conditions for biomass pretreatment are listed in table 1.

Table 1: techniques and representative reaction conditions for lignocellulosic pretreatment

Although efforts have been made in the past decades to enhance the pretreatment of lignocellulose, dilute acids, SO are included₂Current mainstream technology for pH control, AFEX, ARP, flow through, organic solvent and lime pretreatment due to high processing cost and huge costLarge investment risks have not been commercialized on a large scale. But almost all of the extensively studied pretreatments share one or more common disadvantages: 1) harsh pretreatment conditions (except AFEX), leading to sugar degradation and inhibitor formation; 2) low or moderate cellulose digestibility due to the presence of residual lignin and hemicellulose; 3) the need for high cellulase loading; 4) slow hydrolysis rate due to the important fraction (fraction) of the pretreated lignocellulose remaining crystalline; 5) high utility (utiity)/energy consumption; 6) the enormous capital investment resulting from economies of scale; and 7) low co-availability of other main components of lignocellulose in addition to organic solvents.

Dilute acid pretreatment (DA), typically using (dilute) sulfuric acid, is the most studied pretreatment method. At relatively high temperatures (e.g., 150-. As a result, the post-DA concentrated lignin remains on the crystalline cellulose surface, potentially hindering subsequent enzymatic hydrolysis.

Compared to the Kraft pulping process, the organic solvent pulping process offers the benefits of environmental friendliness, less capital investment, utilization of by-products, and lower raw material transportation costs. Organic solvent pretreatment was developed from organic solvent pulping and was studied in the early 1980 s for the production of fermentable sugars after enzymatic hydrolysis. Typically, organosolv pretreatment uses a lignin extraction solvent blend containing a catalyst such as an acid or base and water/organosolv (e.g., ethanol and methanol) to extract lignin in a high temperature and high pressure digester.

Currently, the Lignol process is being developed in canada as part of a commercial lignocellulosic biorefinery. In this treatment, the lignin extraction step is carried out at about 180 ℃ and about 400psi by passing about 50:50(w/w) ethanol/water plus about 1% H₂SO₄The blend of (a) is run for 30 to 90 minutes. After organosolv treatment, the black liquor (bla) containing sulfur-free lignin, furfural, hemicellulose sugars and other natural chemicals such as acetic acidck li quor) further processing: 1) precipitating and recovering lignin by diluting the black liquor with steam, followed by filtration, washing and drying; 2) recovering and recycling ethanol by flash evaporation of hot black liquor and condensation of water vapour, and distilling the filtrate and washings from lignin precipitation; 3) recovering acetic acid, furfural and extract from distillation column (distillation column), and separating xylose from the stillage; and 4) converting the hemicellulose oligosaccharides to sugars that can be fermented to produce more ethanol or other high value products. The economic analysis report by Lignol Innovations co. suggests that revenue from many by-products, particularly lignin, ethanol and xylose fractions, warrants the economic excellence of small plants (about 100 metric tons per day), which are the second decade of a typical lignocellulosic biorefinery input (input).

Lignocellulose saccharification by concentrated acid is another popular pretreatment method. The dissolution and hydrolysis of native cellulose in concentrated sulfuric acid followed by dilution with water was reported in the literature as early as 1883. Industrial saccharification of wood involves many technical and economic problems such as acid-tolerant equipment, acid recovery and final sugar production. Although a number of commercial processes have been developed since the beginning of the last century in germany, switzerland, japan, the united states and the former soviet union, these problems have not been solved. The technique tested commercially was dilute sulfuric acid (0.4% H) in 1926₂SO₄) The Scholler-Tornesch process; the burges-renegox (Bergius-Rheinau) method using super concentrated hydrochloric acid (41% HCl) was used in 1937 and the concentrated sulfuric acid method using membranes to separate sugars and acids was developed in 1948. In the united states, the Madison (Madison) process developed during world war ii as a continuous rather than batch system based on the Scholler-Torneshch principle. The use of concentrated acid treatment has the advantage of low reaction temperatures, but the cost of corrosion-resistant equipment is very high. The main technical problems with concentrated sulfuric acid are the separation of soluble sugars/solid acids, acid recovery and acid re-concentration.

Recently, a method called a lignocellulosic fractionation method based on a cellulose solvent and an organic solvent (COSLIF) has been developed. Cellulose solvents (e.g., concentrated phosphoric acid or ionic liquids) can disrupt the crystalline structure of cellulose. This pretreatment, which also can be performed at low temperatures (e.g., about 50 ℃) and atmospheric pressure, minimizes degradation of the sugars. Fractionating the biomass using a subsequent washing step; washing with organic solvent for the first time to remove lignin; a second wash with water removes the partially hydrolyzed hemicellulose fragments (and potentially cellulose). The cosif process produces highly reactive amorphous cellulose that can be rapidly enzymatically hydrolyzed and achieve high glucan digestibility.

COSLIF can be regarded as a hybrid technology of cellulosic solvent-based biomass pretreatment, concentrated acid saccharification and organic solvents. This new technology includes lignin removal technology and efficient solvent recycling compared to other cellulose solvent based biomass pretreatment technologies. This technique can be performed at lower temperatures compared to organic solvents, degradation of hemicellulose is minimized (furfural is minimized as the main product), the resulting amorphous fiber material is more reactive than from organic solvents, and different combinations of solvents are used. Unlike concentrated acid saccharification, concentrated phosphoric acid is used for limited hydrolysis, producing long chain polysaccharides that are insoluble in the solvent. Thus, the separation of sugars from concentrated phosphoric acid is a solid/liquid separation. However, in concentrated acid saccharification, the sugar/acid separation is a liquid/liquid separation. COSLIF also differs from most biomass pretreatment technologies (e.g., dilute acid, AFEX, hot water, steam explosion, etc.) in the following respects: the cosif process can produce amorphous cellulose that can be easily and rapidly hydrolyzed, and can be used to separate lignocellulosic components, such as lignin.

Mainstream technology for lignocellulose pretreatment is disclosed in international patent application PCT/US2006/011411 (publication number WO2007/111605), which is incorporated herein by reference in its entirety. In embodiments, this patent application teaches a process comprising the steps of: adding a first solvent to the lignocellulosic material to dissolve cellulose and hemicellulose; adding a second solvent to the precipitated amorphous cellulose and hemicellulose and partially dissolving lignin; separating cellulose and hemicellulose from lignin; separating hemicellulose from cellulose; recovering the product and recycling the first solvent and the second solvent. The process of the invention thus comprises separating the glucose-containing cellulose from the mixed sugar-containing hemicellulose. Also included are various organic solvents for fractionating cellulose, lignocellulose, lignin, and acetic acid, and various mechanical or electromechanical devices for separating solids (e.g., cellulose) from liquids (e.g., organic solvents).

Disclosure of Invention

Problems to be solved by the invention

The present invention provides a solution to the shortcomings of the currently available technology. The present invention provides novel methods for converting plant material (including cellulose, hemicellulose, and lignocellulose-containing material) into useful energy sources, such as carbohydrates, ethanol, and hydrogen. In general, the present invention provides novel lignocellulosic pretreatments effective to overcome the deficiencies of currently commercially available technologies. Among other things (ammonium other things), the present invention better converts plant material into useful energy by: 1) extending the use of concentrated acids to all cellulosic solvents (use that unexpectedly provides advantageous characteristics), and 2) utilizing a super cellulosic solvent (e.g., polyphosphoric acid, or concentrated phosphoric acid and P₂O₅Or P is₂O₅Steam, or H₃PO₄/P₂O₅Mixtures of (b) to reduce the volume of solvent used. The present invention, among other things, increases the conversion of plant material to useful carbohydrates, which can be converted into energy (among other things, the amongother nutrients)) by the following steps: 1) applying a one-step solvent to both the precipitated amorphous form of cellulose and hemicellulose and using the one-step solvent to dissolve the lignin, and 2) stripping (striping) at least the amorphous cellulose and hemicellulose using low temperature steam at or below atmospheric pressure.

The present invention shows improvements over the currently known art, including improvements over certain aspects of the previously mainstream technology (such as that disclosed in WO 2007/111605). Among these improvements, the present invention in embodiments specifically does not contain the separation of C5 and C6 sugars by eliminating the step of separating cellulose from hemicellulose and its hydrolysis intermediates. Other improvements provided by embodiments of the invention include reducing the amount of organic solvent used to produce the end product used in energy production, reducing water consumption by steam spraying to remove the organic solvent. Furthermore, the present methods provide in embodiments increased efficiency of lignin removal. The present process, which is useful for softwood, therefore eliminates the sugar concentration step that is conventionally performed after hydrolysis of amorphous cellulose. The improvements provided by the present invention provide a surprising increase in sugar yield from lignocellulosic material. That is, the process according to the invention can produce particularly high levels of the C5 sugar liquor and the C6 sugar liquor (greater than 100 grams of sugar per liter). This titration amount is unexpectedly higher than the typical titration amount previously disclosed in WO2007/111605 (which yields approximately 25g/L of sugar liquor).

Other advantages achieved by the present invention include, in embodiments, reducing the required initial capital investment by: (i) the fractional distillation columns for both organic solvents are simplified to a single flash or several tray distillation system that recovers only one organic solvent, (ii) the number of washing steps is reduced and (iii) the cellulose solvent recycle process is simplified. Additional advantages achieved by embodiments of the present invention include reduced economic dependence on potential benefits of the by-products (acetic acid and/or lignin) to make the process economically viable, and reduced energy consumption required for lignocellulosic particles.

Accordingly, in one aspect, the present invention provides a method of pretreating lignocellulose for degradation into compounds useful in energy production. Generally, the method comprises: digesting lignocellulose with polyphosphate; precipitating cellulose and hemicellulose with a solvent or a mixture of solvents; washing the precipitated cellulose and hemicellulose with a solvent; and stripping the washed precipitate to remove the solvent. The method further comprises reducing the particle size of the lignocellulose as a whole prior to degrading the lignocellulose with polyphosphate. In embodiments, the method is a method of degrading lignocellulose to more than one subunit component (e.g., cellulose, hemicellulose, and lignin) or to more than one small compound (e.g., sugar) that can be used as an energy source. In other embodiments the method is a method of producing cellulose, hemicellulose, lignin, or a combination of two or all three thereof.

The pretreatment process may include additional process steps to provide a process for producing one or more compounds for use as an energy source. In particular, the method may be a method of producing more than one sugar, including but not limited to the C5 sugar and the C6 sugar, such as glucose, xylose, mannose, and galactose. Generally, a method for producing a source from lignocellulose comprises: digesting lignocellulose with polyphosphate; precipitating cellulose and hemicellulose with a solvent or a mixture of solvents; washing the precipitated cellulose and hemicellulose with a solvent; stripping the washed precipitate to remove the solvent; and exposing the precipitate to one or more cellulose or hemicellulose degrading enzymes under conditions such that the enzymes degrade the cellulose, hemicellulose, or both. In embodiments, the method may include isolating or purifying degradation products, such as one or more sugars, from the reactants.

In another aspect, the present invention provides a system for pretreating lignocellulose. Generally, the system comprises at least one vessel, vessel (vessel) or the like for digesting lignocellulose, for mixing and precipitating cellulose and hemicellulose and for extracting lignin, for washing precipitated cellulose and/or hemicellulose and for stripping solvent from precipitated cellulose and/or hemicellulose. Preferably, the system comprises separate containers, vessels or the like for said respective different functions. In embodiments, the system may additionally comprise means for reducing the size of the lignocellulosic material to: this size facilitates the degradation of the lignocellulosic material into cellulose and/or hemicellulose. In embodiments, the system is a system for degrading lignocellulose. In other embodiments, the system is a system for producing cellulose, hemicellulose, lignin, or a combination of two or all three thereof from lignocellulose.

In embodiments, the system further comprises at least one container, vessel, or the like for separating lignin. For example, the system can include a distillation column capable of separating lignin from the organic solvent and polyphosphate. In some embodiments, the system includes an oven for separating polyphosphate from other materials. In these embodiments, the polyphosphate may be reused in subsequent degradation of lignocellulose using the system.

In another embodiment of the system, a container, vessel, or the like is included for hydrolyzing cellulose and/or hemicellulose into small compounds (e.g., sugars) that can be used as an energy source. For example, the system can include a hydrolysis tank in which cellulose and/or hemicellulose can be enzymatically hydrolyzed to sugars.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the system of the present invention and, together with the written description, serve to explain certain principles of the invention.

Fig. 1 is a schematic diagram of an embodiment of a system for degrading lignocellulose to lignin, and a mixture of cellulose and hemicellulose, or both.

Fig. 2 is a schematic of an embodiment of a system for degrading lignocellulose to a mixture of C6 sugars and C5 sugars, ethanol, and lignin.

Fig. 3 is a schematic diagram of an embodiment of a system for degrading lignocellulose to lignin, and a mixture of cellulose and hemicellulose, or both.

Fig. 4 is a schematic of an embodiment of a system for degrading lignocellulose to a high concentration of C6 sugars and a C5 sugar mixture, ethanol, and lignin.

Fig. 5 is a schematic diagram of an embodiment of a system for degrading lignocellulose to lignin, and a mixture of cellulose and hemicellulose, or both.

Fig. 6 is a schematic of an embodiment of a system for degrading lignocellulose to a mixture of C6 sugars and C5 sugars, and lignin.

Detailed Description

Reference will now be made in detail to the exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. It is to be understood that the following detailed description is not a limitation of the invention, but is intended to provide the reader with a better understanding of certain aspects and features of the invention.

Currently known techniques for converting plant material into useful energy sources have some limitations. Among these limitations are: 1) amorphous cellulose found in the aqueous phase of compositions known for the production of energy sources has a low degree of sugars (-20-25 g sugar/L). Therefore, it is desirable to reconcentrate the dilute sugar liquor to a high sugar liquor (>100g sugar/L) prior to fermentation; 2) some of the by-products are not available on the market, or if they are, as in the case of lignin, do not produce large quantities of high quality by-products (e.g., lignin); thus, prior to the development of a robust lignin market, it was difficult to use and sell lignin at a reasonable price; 3) the currently available technology requires high capital investment for the distillation columns used in currently known systems to separate acetic acid and acetone; and 4) potentially high processing costs for organic solvent separation and recycling. The present methods and systems address these limitations by providing a more robust method for the commercial conversion of plant material to useful energy sources.

With respect to the first limitation described above, the present disclosure includes a method of removing an organic solvent from an amorphous cellulose and hemicellulose mixture produced after washing with the organic solvent by stripping, preferably by evaporating the organic solvent using steam. For example, in the present methods and systems, the second scrubber of the above-described system may be replaced by one or more vacuum dryers or strippers. The use of these dryers or strippers produces hydrated amorphous cellulose and hemicellulose products whose hemicelluloses can be broken down, for example, by hydrolysis by enzymes (e.g., hemicelluloses-degrading cellulases), acids, microorganisms, or combinations thereof. Typically, the cellulose/hemicellulose composition produced by steam stripping has a solids content of about 20-30% and is well suited for direct hydrolysis by enzymes, acids and/or microorganisms to produce a high concentration sugar liquor. Therefore, according to the present invention, a sugar solution with a high concentration can be obtained after hydrolysis. In a preferred embodiment, part of the residual organic solvent (e.g. ethanol, butanol, acetone) from the amorphous carbohydrate is recycled after the hydrolysis step or even after the fermentation step. Unlike previously known designs, the present system and process are capable of producing a mixed stream (stream) containing both pentoses and hexoses rather than two separate streams of pentoses and hexoses.

With respect to the second limitation noted above, in view of the currently available methods, the present method and system, in embodiments, includes combusting H₃PO₄Lignin/extract mixture for regeneration of P₂O₅Or superphosphoric acid. In this embodiment, lignin is used as a fuel similar to the process in paper industry.

With respect to the third limitation discussed above, in embodiments, the present system and method replaces the expensive fractionation and distillation columns with simple distillation columns or flash systems. This replacement can reduce the initial total investment, perhaps by more than 30%.

With respect to the fourth limitation described above, the new design disclosed herein can greatly reduce the processing cost with a smaller amount of organic solvent recycle and a simpler recovery process.

In one aspect, the present invention provides a method of pretreating lignocellulose for degradation into compounds useful in energy production. Generally, the method comprises: digesting lignocellulose with polyphosphate; precipitating cellulose and hemicellulose with a first solvent or a mixture of solvents; washing the precipitated cellulose and hemicellulose with a second solvent; and stripping the washed precipitate to remove the solvent.

According to the method, digestion of lignocellulose involves mixing a polyphosphate (i.e., a hypercellulose solvent; superphosphoric acid) with lignocellulose. The lignocellulose may be provided in a purified, semi-purified or unpurified state. For example, it may be provided in a simple or complex composition comprising lignocellulose as the substantially solid part of the composition. The composition may comprise other biological materials and one or more solvents, such as water. The digesting step further comprises maintaining the lignocellulose in contact with the polyphosphate under the following conditions: polyphosphates decompose or digest lignocellulose into its subunit components cellulose, hemicellulose, and lignin. The digestion is carried out to solubilize preferably at least 50%, more preferably at least 90%, and most preferably substantially all of the cellulose and hemicellulose present.

According to the method, the dissolved cellulose and hemicellulose are then precipitated with the first solvent or the mixture of first solvents. The precipitation is produced by mixing the digested lignocellulosic composition with one or more solvents under conditions such that at least some of the cellulose and/or hemicellulose precipitates. In this step, preferably at least 50% is precipitated, more preferably at least 90% is precipitated, and most preferably substantially all of the amorphous cellulose and dissolved hemicellulose is precipitated.

The step of precipitating cellulose and/or hemicellulose further comprises dissolving and/or extracting lignin present in the composition. Preferably at least 20%, more preferably at least 50%, and most preferably substantially all of the lignin is separated from the cellulose and hemicellulose in this step.

According to the method, the first solvent may be any solvent or combination of solvents suitable for precipitating cellulose, hemicellulose, or both, and for dissolving lignin. Preferably the first solvent comprises one or more of the following: methanol, ethanol, 1-propanol, 2-propanol, acetone, propionaldehyde, 1-butanol, 2-butanol, n-butyraldehyde, butanone (methyl ethyl ketone), tert-butanol, and water. In a preferred embodiment, the solvent comprises ethanol, butanol, acetone, water, or a combination of two or more thereof. OthersSolvents include, but are not limited to, CO₂Or CO₂With one or more of the solvents listed above, or a solvent with properties similar to the separation of carbohydrates (e.g., oligomeric to polymeric carbohydrates) from lignin, acetic acid, and (poly) phosphoric acid.

The process of the present invention further comprises washing the precipitated cellulose and hemicellulose with a second solvent or combination of solvents. The second solvent may be any solvent or combination of solvents suitable for washing cellulose and/or hemicellulose. Preferably, the solvent is a solvent suitable for removing phosphoric acid from cellulose and/or hemicellulose. In a preferred embodiment, the second solvent is one of the solvents listed above as preferred first solvents, or a mixture of two or more thereof. In some preferred embodiments, the solvent comprises ethanol, butanol, acetone, water, or a combination of two or more thereof.

The washing step results in the separation of amorphous cellulose and hemicellulose from substantially all of the lignin and phosphoric acid present in the digestion and precipitation composition. As described in more detail below, lignin, phosphoric acid, and other non-cellulosic or hemicellulose components may be further processed in certain embodiments.

The washed amorphous cellulose and hemicellulose are then freed of residual solvent by any suitable means. Such as by exposing the washed precipitate to vacuum, heat, steam stripping, evaporation, or a combination of these to evaporate the solvent from the precipitate. Evaporation is preferred, and more preferably low temperature evaporation alone or in combination with vacuum is used to evaporate the solvent from the precipitate. The present method provides a fast, efficient and inexpensive method of removing the first/second solvent from the precipitate compared to currently used methods that rely on one or more water washing steps. The reduction in water usage not only reduces the cost of implementing the process, but also provides a higher quality product. More specifically, the use of water washing requires multiple washes and produces a product with an extremely high water content that typically must be removed before the product can be provided in a useful form. However, according to the present process, small amounts of water in vapor form can be used to evaporate the solvent and provide useful products. Because a small amount of steam is required, less water is used in the process, resulting in cost savings. Furthermore, the stripped product produced has a significantly higher solids content than the product obtained by previous processes, which makes it directly usable in further work-up reactions. Thus, the time to make the product is reduced according to the equipment and cellulose and hemicellulose processing requirements.

The resulting combination of hydrated amorphous cellulose and amorphous hemicellulose is suitable for any purpose. In the embodiments discussed in detail below, the hydration product is used as a feedstock for hydrolysis and/or fermentation reactions to produce concentrated sugar compositions and/or organic solvents. Advantageously, the use of steam to strip solvent from cellulose and hemicellulose produces a product with a detectable, even considerable, water content, which is preferably used for subsequent treatment of cellulose and hemicellulose. Wherein steam is used as stripping agent in the stripping process, the dried amorphous cellulose and hemicellulose are apparently not in a dry state due to the presence of water. However, for ease of discussion, the product referred to herein is referred to as "dried". Indeed, in a preferred embodiment, if the cellulose and/or hemicellulose comprises a majority but not all of the remainder, the dried cellulose and hemicellulose may contain a significant amount of water, e.g., at least 50% (w/w), at least 60% (w/w), at least 70% (w/w), at least 75% (w/w), or at least 80% (w/w) water.

In addition to the steps listed above, the method of pretreating lignocellulose may comprise steps involving pretreatment of the raw material and post-treatment of non-cellulosic and non-hemicellulosic matter. For example, prior to digestion, the lignocellulosic material may be treated in a number of ways to provide an overall reduction in the size of the lignocellulosic particles. Additionally, in embodiments, prior to digesting lignocellulosic material (which may be, for example, hardwood, softwood, recycled paper, waste paper, forestry waste (forest trimmings), pulp and paper waste, corn stover, corn fiber, wheat straw, rice straw, bagasse, or switchgrass), it may be washed with water, its moisture content may be altered, or it may be adjusted in any other desired manner. In a preferred embodiment, the lignocellulosic material is adjusted to have a moisture content of about 5-30%, more preferably about 10-20%, and most preferably about 15%. Lignocellulosic biomass having a high soluble sugar and/or protein content may be pre-extracted by a solvent (e.g., hot water) to remove these extractives (sugars or proteins) prior to entering the digester.

Another optional step in the pretreatment process is a separation step between washing the amorphous cellulose and hemicellulose and stripping the washed product. This separation step may be accomplished by any suitable method, including, but not limited to, known liquid/solid separation techniques, such as filtration and centrifugation.

Another optional step for the process is to collect and reuse the released solvent, typically by evaporation/volatilization during stripping. Advantageously, the solvent may be collected at this step and reused as a solvent for precipitating and washing cellulose and/or hemicellulose.

In some embodiments, the lignin, phosphoric acid, solvents, and other materials removed in the washing step are further treated to provide byproducts. For example, a wash solution can be passed to a distillation column to separate components based on their physical properties (e.g., volatility). Likewise, the wash solution may be subjected to any of a number of liquid/solid separation techniques, such as filtration and centrifugation, to effect material separation based on size, weight, density, and the like. In a preferred embodiment, the lignin is removed from the other components and collected as a high purity by-product. In a highly preferred embodiment, the wash liquor is first subjected to a distillation process to remove and collect the solvent or solvents (e.g., ethanol), and the non-solvent fraction is subjected to a liquid/solid separation technique or techniques to separate the lignin from the remaining material.

In embodiments, the wash solution, or components of the wash solution remaining after distillation and/or liquid/solid separation, may be heated at elevated temperatures to produce by-products. For example, the distilled and liquid/solid separated wash liquid can be heated in a furnace or other similar unit operation (e.g., wet oxidation) to produce by-products, such as ash (ash) and polyphosphoric acid. As with the solvent optionally recovered from the stripping step and optional distillation treatment, polyphosphoric acid can be reused in the process, thus increasing the cost efficiency of the process as a whole.

It is noted here that prior processes in this area of technology use expensive fractional distillation columns (fractionation columns) with high plate numbers to separate volatile components (e.g., solvents, non-solvent short chain carbon molecules, etc.). When the present invention includes the use of such columns, it has been found that the use of a simple distillation column provides for suitable separation and the production and accumulation of by-products.

In addition to the above process steps, with or without optional steps, the present invention provides additional steps resulting in a process for producing one or more compounds for use as an energy source. For example, the process may be a process for producing a sugar, a solvent such as an alcohol, or both. Generally, a method of producing a compound for use as an energy source includes: digesting lignocellulose with polyphosphate; precipitating cellulose and hemicellulose with a first solvent or solvent mixture; washing the precipitated cellulose and hemicellulose with a second solvent; stripping the washed precipitate to remove the solvent; and hydrolyzing or otherwise breaking down the cellulose and/or hemicellulose into subunit components. In a preferred embodiment, the above-described pretreatment process is used to produce relatively dry amorphous cellulose and amorphous hemicellulose for use in a process for producing energy compounds. The relatively dry cellulose and hemicellulose are exposed to conditions that break down the cellulose and hemicellulose into simpler compounds. The condition may be any condition suitable for achieving the goal. For example, cellulose and hemicellulose may be exposed to a combination of soluble or solid acids, one or more enzymes, one or more microorganisms, or a lytic agent. In exemplary embodiments, the cellulose/hemicellulose is exposed to one or more cellulose or hemicellulose degrading enzymes (e.g., cellulases) under conditions such that the enzymes degrade the cellulose, hemicellulose, or both.

In embodiments, the method may include isolating or purifying degradation products, such as one or more sugars, from the reactants. For example, known liquid/solid separation techniques can be used to separate sugars (e.g., glucose, galactose, mannose) from cellulose and hemicellulose, as well as from enzymes and/or other materials present in the degradation reaction composition. Advantageously, when steam stripped amorphous cellulose and hemicellulose are used as reactants, the reactants are present at a solids content of about 20% to 30%. Due at least in part to this high solids content, very high sugar concentrations, on the order of 100 grams of sugar per liter (order), can be achieved.

Note that while the production of sugar is a preferred embodiment, the present invention also encompasses the production of other products. For example, the hydrolysis reaction conditions can be set such that the cellulose and hemicellulose are predominantly or completely converted to ethanol as the desired end product. Thus, in exemplary embodiments, one or more microorganisms capable of degrading cellulose and/or hemicellulose and capable of fermenting sugars to alcohols (e.g., ethanol) can be combined with cellulose and hemicellulose under the following conditions: this condition degrades cellulose and hemicellulose and ferments the resulting sugars to alcohols. The alcohol produced by the microorganism can then be collected for use as an energy source (e.g., an energy source to power an internal combustion engine). Alternatively, the alcohol may be used for any other suitable purpose, including as a solvent for precipitation or washing in the present process.

As will be apparent to those skilled in the art, the method includes one or more additional steps that may be included to increase the cost effectiveness of the method. For example, substances from the hydrolysis reaction which are not required for its energy production capacity can be removed, for example, by solid/liquid separation techniques. These materials can then be purified or further processed to produce useful materials. In a preferred embodiment, solid calcium phosphate from a hydrolysis reaction can be reacted with sulfuric acid to produce waste calcium sulfate and phosphoric acid that can be used as a cellulose solvent.

In addition to the inventive aspects relating to the method, the present invention provides a system for pretreating lignocellulose for the production of cellulose and/or hemicellulose, and for the production of one or more substances useful as energy sources. Generally, the system of the invention provides hardware, solvents, and/or reactants for performing the process of the invention. Thus, in embodiments, the system comprises a vessel for digesting lignocellulose, precipitating and/or washing cellulose and hemicellulose, and stripping amorphous cellulose and hemicellulose solvents. In further embodiments, the system comprises one or more distillation or fractionation/distillation columns, one or more solid/liquid separators, and one or more furnaces. In another embodiment, the system comprises one or more hydrolysis vessels. Again, the system may include one or more vessels for altering the size, moisture content, etc. of the feedstock (which is used to provide the lignocellulosic material to be worked on). A system according to the present invention may include, but does not necessarily include, solvents and reactants for the production and isolation of products and by-products.

In any of the embodiments described herein, the vessel can be a conventional continuous stirred tank, continuous tubular reactor, or batch tank. Any vessel may be used if there is a method of moving solid, liquid and gaseous materials into and out of the system. To reduce mass transfer limitations between the solvent and solid phase, and to increase the approach rate towards phase equilibrium, it is preferred to mix the vessel contents to some extent. The materials of construction are selected based on the solvent and process conditions selected and the flexibility required for the particular vessel. In general, no special vessels are required due to the moderate conditions for carrying out the process of the invention.

Other general parameters and considerations for systems and methods for pretreating lignocellulose and producing sugar and other energy sources are discussed in WO2007/111605, which is incorporated herein by reference in its entirety.

Turning now to the drawings, FIG. 1 depicts a diagram showing an embodiment of a system and method for converting plant matter into useful energy. The description relates to the use of embodiments of the system for carrying out the method according to the invention.

A feedstock comprising 1.2kg of a lignocellulose-containing biomass at 15% moisture (having an average particle size of less than 0.5 cm) was placed in a 1-digester 3, 2 and 3 liters of Super Cellulose Solvent (SCS) were added. Note that SCS is preferably a polyphosphateAcid salts or phosphoric acid. Additionally, while 0.5cm or small particle size wet wood cellulose is described herein, the feedstock may be any size wet wood cellulose, including but not limited to a range below 2.5 cm. SCS in this example is polyphosphate (Poly-P) used at a concentration of 85%₂O₅) The polyphosphate salt (poly-P)₂O₅) With super-concentrated phosphoric acid (e.g. P)₂O₅>70%) in the form of vapor or droplets. Approximately 6kg of polyphosphate was added. The composition is mixed thoroughly in digester 3. The reaction time is from several minutes to several hours. The mixing of water and acid is an exothermic process; relatively high temperatures (e.g., 50 ℃ to even 120 ℃) have been found to be appropriate for the dissolution of cellulose. At this time, the conditions are suitable for partial cellulose and hemicellulose hydrolysis. The ratio of lignocellulose (dry weight) to P, although the ratio may be any suitable ratio, such as a ratio from 1:1 to 1:10, such as 1:1 to 1:5₂O₅Is about 1: 6. When tested, the dissolved lignocellulose appeared as a gel.

After digesting the lignocellulose in the digester 3, the mixture is transferred 4 to a precipitation tank 5, to which water is first added 6 to precipitate the dissolved cellulose and hemicellulose. High Volatile Solvent (HVS) ethanol at a concentration of 80% 6 was added in an amount of 10 liters to precipitate more cellulose and hemicellulose while dissolving lignin. Alternatives to ethanol in this step include other solvents such as acetone and methanol. In addition, CO may be used₂More lignin is dissolved at high pressure. An additional option is to add a mixture of water and a highly volatile solvent.

After precipitation, the mixture is transferred 7 to a washer 8. In the washer 8, the precipitated cellulose and hemicellulose are washed with 9 additional HVS (now ethanol) and the liquid solvent is effectively removed. Depending on the washing efficiency, the mixture was washed with any amount of about 80% ethanol in 10-20 liters. The scrubber, which is a solid/liquid separator, is a counter current washing device or centrifuge. However, in other embodiments, it may be any of a number of conventional filtration devices, such as a belt filter press (pressure belt filter) and a screen drive, to name a few(screen driver). After solid/liquid separation, 14 liquid phases were removed. The liquid phase contains some solvent, phosphoric acid and lignin. In a typical test (typical run), the liquid composition contains 99% H₃PO₄And additionally comprises about 50% of the initial lignin from the biomass. Which further comprises ethanol and water.

The washed solid phase comprises amorphous cellulose and hemicellulose as well as ethanol. In a typical test, the solid phase comprises 0.40kg cellulose and 0.2kg hemicellulose, and the total weight is 2.3 kg. The composition is transferred 10 to a stripper 11. In this example, 12 carbon dioxide was used to strip and dry the cellulose and hemicellulose and to remove ethanol 13. In alternative embodiments, vacuum or heat or steam may be used in place of carbon dioxide. In the test using steam, the amount of ethanol removed was 1.29kg, representing a removal efficiency of 95%. The resulting residue is almost dry amorphous cellulose and hemicellulose, which is removed 15 from stripper 11.

Fig. 2 depicts a diagram showing an embodiment of a system and method for converting plant matter into a useful energy source. The description relates to the use of embodiments of the system for carrying out the method according to the invention. Note that this embodiment includes the systems and methods described above with respect to fig. 1, as well as additional system components and method steps.

In the system and method according to fig. 2, relatively dry amorphous cellulose and hemicellulose having a moisture content of 75% is transferred 15 to a hydrolysis tank 16. Cellulase and hemicellulase were added as enzymes 17, and the pH of the composition was adjusted to a suitable value by adding alkali 18 (calcium carbonate). When the degradation of cellulose and hemicellulose was completed by enzymes, 19 highly concentrated sugars were obtained. The concentration of the sugar was found to depend on the ratio of solid phase/enzyme solution. Depending on the loading of the enzyme and the nature of the enzyme, the hydrolysis time may range from a few hours to a few days. In the hydrolysis step, a small amount of residual highly volatile solvent can be removed.

As part of the system and method described in fig. 2, a flash vessel 20 is also included. In the flash evaporationIn the vessel, the highly volatile solvent (ethanol in this example) is separated 21 from the other scrubber liquid fractionation components. Small amounts of acetic acid typically remain in the liquid phase, particularly where it is preferred not to use high vacuum or high temperatures for its separation in order to save processing costs and reduce capital investment. The residual liquid phase comprises phosphoric acid, solvent-dissolved lignin, lignocellulosic extract, acetic acid and small amounts of carbohydrates. In order to save capital investment costs and disposal costs, the liquid phase is transferred 22 to a furnace 23 and directly combusted within the furnace 23 using the energy stored in the lignin. In a typical test, the waste material contained about 0.08kg of lignin prior to combustion. Collecting 24 ash (mainly P)₂O₅Depicted as SCS in the figure) and can be used for the next round of pre-processing.

Turning now to fig. 3, another embodiment of the present system and method for producing cellulose and hemicellulose from lignocellulose is schematically depicted. As shown in fig. 3, raw material lignocellulose containing material is introduced 1 into a digester 3. The feedstock has a dimension of less than about 0.5cm in its longest direction and has a moisture content of about 15%. Polyphosphate is added 2 to a digester 3 and the lignocellulosic material is thoroughly mixed and digested to produce a slurry comprising mainly cellulose, hemicellulose and lignin as biological products. The digested material is transferred 4 to a precipitation tank 5. During the transfer, an 80:20(vol/vol) mixture of ethanol to water was added 6 to the mixture. In the precipitation tank 5, cellulose and hemicellulose are precipitated, and lignin is dissolved. The mixture is then transferred 7 to a scrubber 8 to which 9 additional 80:20 ethanol to water is added. Separation of solid and liquid fractions: the liquid fraction is collected 14. The solid fraction is transferred 10 to a stripper 11. In stripper 11, low temperature steam is exposed 12 to the solid material to evaporate the ethanol solvent. The evaporated ethanol (with steam/water) is removed 13 from stripper 11 and collected in solvent collection tank 27.

The stripped solid material is transferred 15 to a screw dryer 28 where additional ethanol is collected and transferred 29 to a solvent collection tank 27. The dried cellulose and hemicellulose cake is collected 30 from the screw dryer 28.

Fig. 4 depicts a diagram showing another embodiment of a system and method for converting plant matter into useful energy. The description relates to the implementation of the method according to the invention with an embodiment of the system. Note that this embodiment includes the system and method described above with respect to fig. 3, and also includes additional system components and method steps.

As shown in fig. 4, the raw material lignocellulose containing material is introduced 25 into a cutter 26, wherein the raw material is reduced to a dimension below about 0.5cm in its longest direction. In this step, the feedstock may be subjected to additional treatments, such as by washing to remove certain lignocellulosic extracts (e.g., proteins and certain soluble sugars), to provide an enriched lignocellulosic material for further processing. After the action of the cutter 26, the lignocellulosic material, typically having a moisture content of about 15%, is transferred 1 to the digester 3. Polyphosphate is added 2 to a digester 3 and the lignocellulosic material is thoroughly mixed and digested, producing mainly cellulose, hemicellulose and lignin as biological products. The digested material is transferred 4 to a precipitation tank 5. During the transfer, an 80:20(vol/vol) ethanol water mixture was added 6 to the mixture from solvent holding tank 27. In the precipitation tank 5, cellulose and hemicellulose are precipitated, and lignin is dissolved. The mixture is then transferred 7 to a scrubber 8 to which 9 further 80:20 ethanol to water is added from the solvent collection tank 27. Separation of solid and liquid fractions: the liquid fraction is transferred 14 to fractionation/distillation column 20 and the solid fraction is transferred 10 to stripper 11. Low temperature steam is exposed 12 to the solid material in stripper 11 to evaporate the ethanol solvent. The evaporated ethanol (with steam/water) is removed 13 from stripper 11 and collected in solvent collection tank 27.

The stripped solid material is transferred 15 to a screw dryer 28 where additional ethanol is collected and transferred 29 to a solvent collection tank 27. The dried cellulose and hemicellulose cake is transferred 30 from the screw dryer 28 to the hydrolysis tank 16. Cellulase and hemicellulase enzymes were added 17 to enzymatically digest cellulose and hemicellulose and the pH was adjusted with alkali 18 to optimize the enzyme activity. After hydrolysis, the mixture is transferred 31 to a solid/liquid separator 32. The solid/liquid separator is a centrifuge in this example, but any suitable separator may be used. In the liquid phase, 33 high concentrations (more than 30g/l) of sugars were obtained. In some batches, the high concentration sugar solution portion is reintroduced 34 into the hydrolysis tank. Soluble sugars can be mixed with the dried amorphous cellulose and hemicellulose to be hydrolyzed again to give a solution of higher sugar concentration, or can be used directly in the fermentation.

In certain configurations of the system and method, the system is primarily used to produce sugars for use as fuel. In other configurations, the systems and methods are configured for the production of one or more alcohols. The hydrolysis tank and components thereof can be modified to achieve the desired production. For example, where sugar is desired, the hydrolysis tank may contain the following acids or enzymes: the acid or enzyme is capable of degrading cellulose and hemicellulose into its component sugar building blocks (blocks). Where an alcohol (e.g., ethanol) is desired, the hydrolysis tank may contain microorganisms capable of degrading cellulose and hemicellulose to an alcohol. In this embodiment, the alcohol may be collected. In the embodiment depicted in fig. 4, the production of both sugar and ethanol is depicted. In the figure, the ethanol produced by the hydrolysis tank is collected and transferred 35 to the solvent collection tank 27. Of course, the produced alcohol may be transferred to another vessel and used for other purposes.

Solid/liquid separator 32 also produces a solid phase that is transferred 36 to reactor 37. Sulfuric acid and solid calcium phosphate are added to the solid phase in reactor 37 and allowed to react. After the reaction, solid calcium sulfate and phosphoric acid are produced.

Returning now to the liquid phase produced as a result of the washing in the washer 8, which mainly comprises ethanol, phosphoric acid and lignin. The liquid phase is transferred 14 to a fractionation/distillation column 20. The fractionation/distillation column 20 separates acetic acid 38 and ethanol 21 from the other components. Typically, the recovered ethanol is an 85% solution. The remaining components of the wash liquid phase are transferred 39 to the solid/liquid separator 23 where the lignin is separated 40. The remaining components of the wash liquor are transferred 22 to a furnace 24 and combusted to produce ash and polyphosphate for use in subsequent batch degradation.

Fig. 5 depicts another exemplary embodiment of the present systems and methods for degrading lignocellulosic material to cellulose and hemicellulose. As shown, feed is added 1 to digester 3. Polyphosphate is also added 2 to the digester 3, mixing the material thoroughly and degrading the lignocellulose into cellulose, hemicellulose and lignin. More specifically, in the digester 3, the lignocellulosic material is brought into contact with P₂O₅Steam or with a terminal P₂O₅Droplets of super concentrated phosphoric acid with a concentration of 83% were mixed well. Although an 83% concentration is used in this embodiment, it is noted that any suitable concentration may be used, such as 70% or more, 75% or more, or 80% or more. The heat released by the mixing of water and polyphosphoric acid or phosphoric acid or mixtures thereof is used to promote biomass dissolution. The temperature may vary from 40 ℃ up to 120 ℃, and preferably from 45 ℃ to 100 ℃, more preferably from 47 ℃ to 90 ℃, and most preferably from 50 ℃ to 85 ℃. The reaction time may vary from a few minutes up to a few hours, but is preferably from 30 to 240 minutes, more preferably from 45 to 180 minutes, and most preferably from 60 to 120 minutes. Typically, the dissolved biomass looks like a slurry.

The digested material is then transferred 4 to a precipitation tank 5 to which a solution of 6 about 80% ethanol is added from a solvent collection tank 27. The mixture is held for a sufficient time to precipitate the cellulose and hemicellulose and dissolve the lignin. The mixture is then transferred 7 to a washer 8, which is washed with 80% ethanol 9 from the solvent collection tank 27. The washed precipitate is then transferred 41 to a solid/liquid separator 42, which in this case is a drum centrifuge, which removes most of the excess solvent (free solvent) and other materials in the wash from the slurry. The 14' liquid fraction is removed, which can be combined with the wash fraction removed in 14. In other embodiments, other mechanical devices (e.g., screw dryers) may be used herein. The solids content resulting from the process and apparatus varies between 5-20%. Preferably the solids content is above 8%, more preferably above 10% and most preferably above 15%. In the figure, the precipitation tank 5 and the scrubber 8 are enclosed (enclosed) in a single box indicated by a dotted line. This indicates that, in some embodiments, a combined single unit reactor can perform both functions. In this embodiment, the precipitation tank 5 and the scrubber 8 are a single unit.

The slurry is transferred 10 to a stripper 11 and ethanol is extracted with low temperature steam 12. The volatilized ethanol is released 13 as ethanol (water vapor) vapor and collected in a solvent collection tank 27. In stripper 11, a slurry containing amorphous cellulose, hemicellulose, residual undissolved lignin plus a small amount of phosphoric acid in an organic solvent (e.g., ethanol) is stripped by low temperature steam at reduced or atmospheric pressure. The slurry typically has a solids content of 5-20%. Preferably the slurry has a solids content of from 5 to 20%, preferably above 8%, more preferably above 10%, and most preferably above 15%. In a typical test, the slurry has a total sugar content of from 40% to 90% based on the weight of solids. Preferably, the sugar content is 60% or more, more preferably 65% or more, and most preferably 80% or more. In this unit operation, low temperature steam (about 60 ℃ C. to 120 ℃ C.) is used. Regardless of the equipment used, the wet biomass slurry is dried in a fluidized bed or spray dryer as are the solid particles. Heat (e.g., from steam) is used to evaporate a majority of the organic solvent (e.g., 80-99% ethanol, preferably at least 85%, more preferably at least 95%, and most preferably at least 98% ethanol). After this operation, the dried biomass typically has a solids content of 10-40%. At this step, it is preferred that the biomass has a solids content of 20% or more, more preferably 25% or more, and most preferably 30% or more, with water and some residual organic solvent (e.g., 5% of the original organic solvent). For later use, the dried cellulose/hemicellulose is discharged 15 from the stripper 11.

Fig. 6 depicts a diagram showing another embodiment of a system and method for converting plant matter into a useful energy source. The description relates to the use of embodiments of the system for carrying out the method according to the invention. Note that this embodiment includes the system and method described above with respect to fig. 5, and also includes additional system components and method steps. As shown in fig. 6, the raw lignocellulosic material comprising the material is introduced 25 into a cutter 26, where the raw material is cut to a size of about 0.5cm or less in its longest direction. In this step, the feedstock may be further treated, for example by washing, to provide an enriched lignocellulosic material for further processing. As in other embodiments using a cutter, the cutter (mill) reduces the biomass particle size to less than 2.54 cm. The moisture content of the biomass may vary from about 5-50%. In this embodiment, the biomass moisture is set to a constant value (10-30%) before the next step. In a preferred embodiment, the water content is set to 15%. The overdried biomass particles may be mixed with water for the desired moisture content. After acting on the cutter 26, the lignocellulosic material, preferably with a moisture content of about 15%, is transferred 1 to the digester 3. The addition of 2 polyphosphate to digester 3 thoroughly mixes and digests the lignocellulosic material, producing mainly cellulose, hemicellulose and lignin as biological products. The digested material is transferred 4 to a precipitation tank 5. During the transfer, an 80:20(vol/vol) ethanol water mixture was added 6 to the mixture from the solvent collection tank 27. In the precipitation tank 5, cellulose and hemicellulose are precipitated and lignin is dissolved. The mixture is then transferred 7 to a scrubber 8 to which scrubber 8 is added 9 further 80:20 ethanol to water from the solvent collection tank 27. The liquid wash is collected and transferred 14 to distillation column 20. The solid phase slurry from the washing step is transferred 41 to a solid/liquid separator 42, in this case a drum centrifuge, to remove most of the excess solvent and other materials in the wash liquid from the slurry. The 14' liquid fraction is removed or combined with the wash liquid fraction removed in 14 or applied directly to distillation column 20. Low temperature steam is exposed 12 to the solid material in stripper 11 to evaporate the ethanol solvent. The evaporated ethanol (with steam/water) is removed 13 from stripper 11 and collected in solvent collection tank 27.

The stripped solid material is transferred 15 to a hydrolysis tank 16. Cellulase and hemicellulase were added 17 to enzymatically digest cellulose and hemicellulose and pH was adjusted with alkali 18 to optimize enzyme activity. In other embodiments, an amount of base (e.g., lime) is used in the hydrolysis tankOr calcium carbonate) to improve the enzyme activity, for example by setting it at the optimum pH for the enzyme. The amorphous cellulose and hemicellulose may be hydrolyzed to soluble sugars using cellulase and/or hemicellulase, or bifunctional enzymes, respectively. The hydrolysis treatment may be carried out in a fed-batch mode, i.e. more wet amorphous cellulosic material with a solids content of more than 20% may be added slowly and stepwise (for better mixing) instead of adding it all at once at the beginning. After hydrolysis with the addition of several batches of wet amorphous cellulose, a high concentration of sugar liquor can be obtained, being more than 100g per litre of soluble hexose and pentose sugars. In addition, high concentration sugar solutions can be mixed with amorphous cellulose for simultaneous saccharification and co-fermentation (SSCF) or Combined Bioprocessing (CBP). Can burn the residual lignin, cellulose and Ca₃(PO₄)₂To remove all organics. Ca can be added by adding concentrated sulfuric acid₃(PO₄)₂The ash content of (a) is regenerated into concentrated phosphoric acid. Some small amounts of organic solvent (e.g. ethanol) are recovered either in the hydrolysis step by vacuum or steam stripping, or after fermentation of sugar to ethanol (suger-to-ethanol).

After hydrolysis, the mixture is transferred 31 to a solid/liquid separator 32. The solid/liquid separator is a centrifuge in this example, but any suitable separator may be used. In the liquid phase, a very high concentration of sugars (greater than 100g/l) is obtained 33. In some batches, the high sugar liquor portion is reintroduced 34 into the hydrolysis tank. In such embodiments, sugar liquor is used in place of water in the solid cellulose to obtain a solution of higher sugar concentration.

In certain configurations of the system and method, the system is primarily used to produce sugars for use as fuel. In other configurations, the systems and methods are configured to produce more than one alcohol. The hydrolysis tank and its components can be modified to achieve the desired production goals. For example, where sugars are desired, the hydrolysis tank may contain an acid or enzyme capable of degrading cellulose and hemicellulose to its component sugar building blocks. Where an alcohol (e.g., ethanol) is desired, the hydrolysis tank may contain microorganisms capable of degrading cellulose and hemicellulose to an alcohol or other product. In such embodiments, the alcohol may be collected. In the embodiment depicted in fig. 6, the production of both sugar and ethanol is depicted. In the figure, ethanol produced from the hydrolysis tank is collected and transferred 35 to the solvent collection tank 27. Of course, the produced alcohol may be transferred to another vessel and used for other purposes.

The solid/liquid separator 32 also produces a solid phase which is transferred 36 to a reactor 37. In the reactor 37, sulfuric acid and solid calcium phosphate are added to the solid phase and allowed to react. After the reaction, solid calcium sulfate and phosphoric acid are produced.

Returning now to the scrubber 8, the resulting liquid phase is scrubbed, which contains mainly ethanol, phosphoric acid and lignin. The liquid phase is transferred 14 to distillation column 20. The distillation column 20 separates ethanol 21 from the other components. The recovered ethanol is typically at a concentration of about 80%. Note that in this embodiment, an expensive fractionation/distillation column is not required, which increases the cost efficiency of the process without significantly reducing product and byproduct yields. A distillation column may be used in all embodiments and thus may be replaced with a fractionation/distillation column in any of the previous exemplary embodiments. In the distillation column, the organic solvent (e.g., ethanol) is recovered through a number of tray distillation columns. The concentration of ethanol concentrated from the column may vary between 50-95%, preferably 50%, more preferably 70%, and most preferably 80%. After or during the removal of the organic solvent, the lignin precipitates at the bottom of the distillation column and can be separated from the aqueous phosphoric acid solution. The remaining liquid phase contains mainly phosphoric acid, some lignin and organic extracts of biomass.

The remaining components of the wash liquid phase are transferred 39 to the solid/liquid separator 23, where the lignin is separated 40 in the solid/liquid separator 23. Washing out the phosphoric acid in the solid lignin by using water or an organic solvent.

The remaining components of the wash are transferred 22 to a furnace 24 and combusted to produce ash and polyphosphate that can be used for subsequent batch degradation. In a furnace, the remaining liquid phase of the organic extract, which contains mainly phosphoric acid, some lignin and biomass, is regenerated into P₂O₅Steam, polyphosphoric acid, or mixtures thereof. The term "furnace" includes wet oxidation. To reduce process costs and furnace size, only the phosphoric acid fraction is completely oxidized to P₂O₅. The phosphoric acid fraction passing through furnace 24 may vary between 1-100%, preferably above 15%, more preferably above 20%, and most preferably above 25%. When the phosphoric acid contains high organic extract, it can be converted into high-purity P₂O₅。P₂O₅May be sublimable; can separate from P₂O₅As a plant fertilizer. Sublimed P₂O₅May be mixed with water to form polyphosphoric acid, concentrated phosphoric acid, or used to pretreat wet biomass, for example, directly in the digester 3.

In many applications, the present method and system are suitable for hardwoods and herbaceous material. If applied to cork, the method and system can be modified in several respects: 1) in the digestion step, some catalyst may be added, such as SO₂(ii) a 2) In the washing step, more lignin can be washed out by using a high-temperature solvent which can dissolve more lignin; 3) before the hydrolysis step, by adding some oxidizing agent, e.g. H₂O₂、O₃High concentration of O₂NO, etc. can remove more lignin. In summary, the above-described process is much simpler than currently known techniques, including, but not limited to, previous patent publications PCT/US2006/011411, PCT/US06/030894, US4,058,011, WO9606207, SU1348396A1(Grinshpan DD, Tsygankova NG, Kaputski FN), DE3035084(US4,839,113), and US6,139,959. While the total revenue required is often much lower than earlier technologies (but higher than other pretreatments), the new design greatly reduces capital investment and processing costs while producing, among other things, high concentrations of cellulose and hemicellulose and sugar hydrolysates suitable for ethanol fermentation.

It will be apparent to those skilled in the art that various modifications and variations can be made in the application of the present invention and in the construction of the present system without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention. It is intended that the specification and examples be considered as exemplary only.

Claims (26)

1. A system for fractionating lignocellulosic biomass, the system comprising the following separate vessels:

a precipitation tank for precipitating cellulose and hemicellulose and for dissolving lignin;

a scrubber in operable communication with the precipitation tank and for washing the precipitated cellulose and hemicellulose to produce washed cellulose and hemicellulose;

a stripper in operable communication with the scrubber and for stripping solvent from the washed cellulose and hemicellulose to produce stripped cellulose and hemicellulose; and

wherein the system does not comprise a separator for separating cellulose from hemicellulose;

wherein where the system further comprises a hydrolysis tank, the system does not comprise a scrubber in direct operative connection with the hydrolysis tank.

2. The system of claim 1, further comprising a digester for digesting a lignocellulose-containing feedstock into particles having a particle size of 0.5cm or less.

3. The system of claim 1, wherein the hydrolysis tank is present in the system and is used to hydrolyze the stripped cellulose and hemicellulose.

4. The system of claim 1, further comprising a distillation column for separating components of a wash liquid from the scrubber, wherein the distillation column is not a fractionation-distillation column.

5. The system of claim 4, further comprising a solid-liquid separator for separating lignin and in operable communication with the distillation column.

6. The system of claim 5, further comprising a furnace for producing ash and in operable communication with the solid-liquid separator.

7. The system of claim 1, further comprising a flash vessel for recycling high volatile solvent and in operable communication with the scrubber.

8. The system of claim 7, further comprising a furnace for producing ash and in operable communication with the flash vessel.

9. The system of claim 1, further comprising a solvent collection tank for recycling ethanol and in operable communication with the stripper, scrubber, and settling tank.

10. The system of claim 1, further comprising a screw dryer in operable communication with the stripper for producing cellulose, hemicellulose, and ethanol.

11. The system of claim 10, further comprising a solvent collection tank for collecting ethanol and in operable communication with the screw dryer.

12. The system of claim 10, wherein the hydrolysis tank is present in the system and the hydrolysis tank is in operable communication with the screw dryer.

13. The system of claim 12, further comprising a solid-liquid separator for producing a solid phase and in operable communication with the hydrolysis tank.

14. The system of claim 13, further comprising a reactor for producing solid calcium phosphate and phosphoric acid and in operable communication with the solid-liquid separator.

15. The system of claim 1, further comprising a solid-liquid separator interposed between and in operable communication with the scrubber and the stripper.

16. The system of claim 2, further comprising a cutter that cuts feedstock, wherein the digester is in operable communication with the cutter.

17. The system of claim 1, further comprising a fractionation-distillation column in operable communication with the scrubber for recovering ethanol.

18. The system of claim 17, further comprising a solid-liquid separator for separating lignin and in operable communication with the fractionation-distillation column.

19. The system of claim 18, further comprising a furnace for producing ash and in operable communication with the solid-liquid separator.

20. A system for fractionating lignocellulosic biomass, the system comprising:

a precipitation tank configured for precipitating cellulose and hemicellulose and for dissolving lignin;

a scrubber configured for washing the precipitated cellulose and hemicellulose to produce washed cellulose and hemicellulose;

a stripper configured for stripping solvent from the washed cellulose and hemicellulose to produce stripped cellulose and hemicellulose; and

wherein an operable connection between the scrubber and the precipitation tank is configured such that, during use, the precipitated cellulose and hemicellulose are transferred from the precipitation tank to the scrubber;

wherein an operable connection between the scrubber and the stripper is configured such that, during use, the solvent and the washed cellulose and hemicellulose are transferred from the scrubber to the stripper;

wherein where the system comprises a hydrolysis tank, the scrubber is not directly operably connected to both the stripper and the hydrolysis tank.

21. The system of claim 20, further comprising a digester for digesting lignocellulose-containing feedstock into particles having a particle size of 0.5cm or less, wherein an operative connection between the digester and the settling tank is configured such that during use, the particles are transferred from the digester to the settling tank.

22. The system according to claim 20, wherein the hydrolysis tank is present in the system and is used for hydrolyzing the stripped cellulose and hemicellulose, wherein a direct operable connection between the stripper and the hydrolysis tank is configured such that during use, the stripped cellulose and hemicellulose is transferred from the stripper to the hydrolysis tank.

23. The system of claim 20, further comprising a distillation column for separating components of a wash liquid from a scrubber, wherein the distillation column is not a fractionation-distillation column, wherein an operative connection between the distillation column and the scrubber is configured such that, during use, components of the wash liquid are transferred from the scrubber to the distillation column.

24. The system of claim 23, further comprising a furnace and a solid-liquid separator, wherein the operative connection between the distillation column and the solid-liquid separator and the operative connection between the solid-liquid separator and the furnace are configured such that, during use, the wash liquid is transferred from the distillation column to the solid-liquid separator and to the furnace.

25. A system for fractionating lignocellulosic biomass by:

i) digesting lignocellulose with polyphosphate, wherein no hemicellulose is removed from the lignocellulose prior to digestion,

ii) co-precipitating cellulose and hemicellulose with a first solvent and dissolving lignin,

iii) separating the dissolved lignin from the precipitated cellulose and hemicellulose resulting from said step ii), and

iv) stripping the first solvent from the precipitated cellulose and hemicellulose from the step iii) by exposing the cellulose, hemicellulose and solvent to steam, vacuum or a combination thereof,

wherein the method provides a mixture of hydrated amorphous cellulose and hydrated amorphous hemicellulose, the system comprising:

a precipitation tank for precipitating cellulose and hemicellulose and for dissolving lignin;

a scrubber for washing the precipitated cellulose and hemicellulose to produce washed cellulose and hemicellulose; and

a stripper for stripping solvent from the washed cellulose and hemicellulose to produce stripped cellulose and hemicellulose;

wherein there is only one scrubber downstream of the precipitation tank and upstream of the stripper.

26. The system of claim 20, wherein there is only one scrubber located downstream of the settling tank.