METHOD FOR PRODUCING FURFURAL FROM BIOMASS MATERIAL CONTAINING PENTOSAN

专利摘要:
METHOD FOR PRODUCING FURFURAL FROM BIOMASS MATERIAL CONTAINING PENTOSAN. Furfural is produced from pentosan-containing biomass material, in high yields, in a production process comprising treating the biomass with a solution containing at least one ?-hydroxysulfonic acid, thereby hydrolyzing the biomass to produce a fur-containing product stream. minus one C5 carbohydrate compound in monomeric and/or oligomeric form and dehydrating the C5 carbohydrate compound in the presence of an acid, in a two-phase reaction medium comprising an aqueous phase and a water-immiscible organic phase, at a temperature in the range of about from 100°C to about 250°C to produce a furfural-containing dehydration product stream. An aqueous stream is separated from the dehydration product which can optionally be recycled to the hydrolysis step
公开号:BR112016030664B1
申请号:R112016030664-3
申请日:2015-08-13
公开日:2021-06-29
发明作者:Juben Nemchand Chheda；Jean Paul Andre Marie Joseph Gishlain Lange；Paul Richard Weider；Robert Lawrence Blackbourn
申请人:Shell Internationale Research Maatschappij B.V.；
IPC主号:

专利说明:

Cross Reference to Related Order
[001] This application claims priority to U.S. Provisional Application Serial No. 62/037,190 filed August 14, 2014, the entire description of which is incorporated herein by reference. Field of Invention
[002] The invention relates to a process for preparing furfural from biomass, and more specifically, to a biomass treatment and production of furfural from materials containing polysaccharides and/or lignocelluloses. Fundamentals of the Invention
[003] Lignocellulosic biomass is seen as an abundant renewable resource for chemicals due to the presence of sugars in plant cell walls. More than 50% of the organic carbon on the Earth's surface is contained in plants. This lignocellulosic biomass is comprised of hemicelluloses, cellulose and smaller portions of lignin and protein. These structural components are comprised primarily of pentose and hexose sugar monomers. Cellulose is a polymer comprised primarily of hemicellulose and condensation polymerized glucose is a precursor of pentose sugars, primarily xylose. These sugars can be converted into valuable components as long as they can be released from cell walls and the polymers that contain them. However, plant cell walls have developed considerable resistance to microbial, mechanical or chemical degradation to produce component sugars. In order to overcome recalcitrance, soil biomass is altered by a chemical process known as pre-treatment. The objective of the pretreatment is to hydrolyze the hemicellulose, break down the protective lignin structure and disrupt the crystalline structure of the cellulose. All of these steps increase the enzymatic accessibility to cellulose during the subsequent hydrolysis (saccharification) step.
[004] The original approaches dating back to the early 19th century involve complete chemical hydrolysis using concentrated mineral acids such as hydrochloric acid, nitric acid or sulfuric acid. Numerous improvements to these processes have been made by gaining higher sugar yields from the biomass feed load. These higher acid concentration approaches provide higher yields of sugars, but due to economic and environmental reasons the acids must be recovered. The main obstacle to the practice of this form of saccharification has been the challenges associated with acid recovery [M. Galbe and G. Zacchi, Appl. Microbiol. Biotechnol. Vol. 59, pp. 618-628 (2002)]. Recent efforts to separate sulfuric acid and sugars using the separation of ionic resin or hydrochloric acid and sugars through an amine extraction process and subsequent thermal acid regeneration have been described in US Patent No. 5,820,687. However, both of these approaches are tedious and costly in practice.
[005] Dilute acidic processes have also been undertaken to carry out chemical saccharification and one such example is the Scholler- Tornesch Process. However, the use of dilute acid requires higher temperatures and this usually results in low yields of the desired sugars due to thermal degradation of the monosaccharides. Countless approaches of this kind have been made in the past and all have failed to overcome economic obstacles. [See, for example, Lim Koon Ong, “Conversion of Lignocellulosic Biomass to Fuel Ethanol--A Brief Review,” The Planter, Vol. 80, No. 941, August 2004, and, “Cell Wall Saccharification,” Ralf Moller , in Productions of the EPOBIO Project, 2006; Published by CPL Press, Tall Gables, The Sydings, Speen, Newbury, Berks RG14 1RZ, UK].
[006] The enzymatic saccharification of cellulose is promising for higher sugar yields under milder conditions and is therefore considered by many to be more economically attractive. Recalcitrance of crude biomass for enzymatic hydrolysis requires a pre-treatment to enhance the susceptibility of cellulose to hydrolytic enzymes. A number of pretreatment methods, as described by Mosier, et al. [Bioresource Technology, Vol. 96, p. 673-686 (2005)], was developed to alter the structural and chemical composition of biomass to improve enzymatic conversion. Such methods include treatment with a dilute acid vapor explosion as described in US Patent No. 4461648, hydrothermal pretreatment without the addition of chemicals as described in WO 2007/009463 A2, ammonia freeze explosion process as described by Holtzapple, MT et al. 59-74], and an organosolv extraction process described in US Patent No. 4409032. Despite these approaches, this pretreatment has been cited as the most expensive process in converting biomass to fuels [Ind. Chem Eng. Res., Vol. 48(8), 3713-3729 (2009)].
[007] A pretreatment that has been extensively explored is a high-temperature dilute sulfuric acid (H2SO4) process, which effectively hydrolyzes the hemicellulose portion of the biomass into soluble sugars and exposes the cellulose so that enzymatic saccharification is good - successful. Parameters that can be used to control pretreatment conditions are time, temperature, and acid loading. These are often combined into a mathematical equation called the combined severity factor. In general, the greater the charge of acid employed, the lower the temperature that can be employed; this comes with an acid cost and the need to recycle the acid. On the other hand, the lower the temperature, the longer the pretreatment process; this comes with the cost of productivity. However, using the higher acid concentrations required to lower pretreatment temperatures below that at which furfural formation becomes easy [B. P. Lavarack, et al., Biomass and Bioenergy, Vol. 23, p. 367-380 (2002)] again requires the recovery of strong acid. If dilute acid streams and higher temperatures are used, the acid pretreatment reaction that passes downstream to enzymatic hydrolysis and subsequent fermentation steps must be neutralized resulting in inorganic salts that complicate downstream processing and require processing systems. more expensive wastewater treatment. This also results in increased chemical costs for acid and base consumption.
[008] More recently, in US20120122152, it was shown that a-hydroxysulfonic acids are effective in the pretreatment and hydrolysis of biomass with the additional benefit of being recoverable and recyclable through the inversion of the acidic primary components (aldehyde, SO2 and Water). This pretreatment process has been shown to provide numerous benefits compared to the pretreatment of dilute mineral acids. However, at low temperature, furfural formation is low.
[009] A method for preparing furfural can use a batch process based on a Quaker Oats technology developed in 1920 using sulfuric acid. The batch process is known to be significantly inefficient. That is, the theoretical yield of furfural is around 30 to 40%, the residence time in the reactor is significant from 4.5 to 5.5 hours, water of 50MT (50000 kg) per 1MT (1000 kg) is consumed of furfural, and a significant amount of harmful substance is included in the effluents. Furthermore, the costs consumed by labor increase considerably.
[0010] Furthermore, whether in batch or continuously, when using this acid catalyst, process corrosion and acid residues are generated, so that it is difficult to separate, recover and recycle a non-reactive raw material and the acid catalyst. Furthermore, the economic efficiency of the process can be very vulnerable according to the increased investment costs of the process installation and low product yield and environmental toxicity, recovery and recycling can be complicated even in the process using an organic solvent. Invention Summary
[0011] The inventions described and taught in this document are directed to methods for the synthesis of organic materials from furfural and similar organic materials from a biomass feedstock with high yields that optionally allow acid-containing aqueous streams from Sugar dehydration steps are extensively recycled into the production system with minimal “loss” of acid.
[0012] We found that the addition of small amounts of mineral acid or organic acid to the process of a-hydroxysulfonic acids produces furfural with high yield.
[0013] In one embodiment of the present invention, there is provided a method for producing furfural from pentosan-containing biomass material: (a) providing a pentosan-containing biomass; (b) contacting the biomass with a solution containing at least one α-hydroxysulfonic acid, thereby hydrolyzing the biomass to produce a product stream containing at least one C5 carbohydrate compound in monomeric and/or oligomeric form, and α-hydroxysulfonic acid; (c) separating at least a portion of the α-hydroxysulfonic acid from the product stream containing at least one C5 carbohydrate compound to provide an acid-removed product stream containing at least one C5 carbohydrate compound and recovering the α-hydroxysulfonic acid in its component form; (d) separating a liquid stream containing said at least one C5 carbohydrate compound and a wet solid stream containing remaining biomass from the acid-removed product; (e) dehydrating the C5 carbohydrate compound in at least a first portion of the liquid stream in the presence of a dehydrating acid, in a two-phase reaction medium comprising an aqueous phase and a water-immiscible organic phase, at a temperature in the range of about from 100°C to about 250°C; (f) separating an organic phase stream containing furfural and an aqueous stream containing the dehydrating acid from the dehydrating product stream; (g) recycling at least a portion of the aqueous stream or a second portion of the liquid stream to step (b); (h) recovering furfural from the organic phase stream.
[0014] The features and advantages of the invention will be apparent to those skilled in the art. Although numerous changes can be made by those skilled in the art, such changes are within the spirit of the invention. Brief Description of Drawings
[0015] This drawing illustrates certain aspects of some of the embodiments of the invention and should not be used to limit or define the invention.
[0016] Fig. 1 schematically illustrates a block flowchart of an embodiment of the furfural production process of the invention from biomass.
[0017] Fig. 2 schematically illustrates a block flow diagram of an embodiment of the furfural production process of the invention from biomass.
[0018] Fig. 3 depicts the xylose conversion and furfural selectivity from acid dehydration at various concentrations of xylose from Example 3.
[0019] Fig. 4 represents the furfural yield (%) at various concentrations of dehydrating acid in a biphasic acid dehydration reaction system of Example 4. Detailed Description of the Invention
[0020] It has been found that the present invention provides an improved method for producing furfural from biomass in a batch, continuous or semi-continuous manner (optionally as a closed-loop process). By using α-hydroxysulfonic acid, the acid can be readily separated by heating or pressure reduction and recycled, and requires only a fraction of a mineral and/or organic acid and fraction of a time compared to the conventional process to dehydrate. the C5 carbohydrate compound, thus increasing efficiency and decreasing complications. Furthermore, by separating a liquid stream containing C5 carbohydrate compound from the wet solids of the product stream from the α-hydroxysulfonic acid pretreatment step, it was found that furfural can be produced without excessive degradation of C6 sugars in the subsequent dehydration step. For example, the controlled return of the slightly acidic aqueous stream after dehydration of C5 carbohydrates extracted from the biomass allows to maintain an optimized reaction process stream. Additionally, the method allows increased amounts of both C5 carbohydrate and C6 carbohydrate-containing intermediate product streams to be efficiently separated and recovered and sent to further improvement and/or purification steps (dehydration, fermentation, etc.), whereas often these intermediate products are lost or destroyed during the treatment steps. Furthermore, the process methods allow higher concentrations of pentosan-comprising biomass to be treated, which increases the product concentration, thus reducing the size of the equipment and facilitating the recovery of valuable intermediates and products in general. Furthermore, the use of in-process extraction methods allows for the recovery of the desired product (furfural) without having to distill or remove too much water with it (as an azeotrope). When carried out in situ, for example during dehydration, it reduces the formation of unwanted products by humins and/or impurities and thus increases the yield of the desired product. Furthermore, in an embodiment where the aqueous stream is recycled to the hydrolysis step, such recycling of the aqueous stream can be partial, for example, using a small fraction of highly acidified wastewater from the dehydration step to neutralize the caustic component of the biomass before treatment with a-hydroxysulfonic acid. This option allows decoupling the acidity of dehydration with the acidity requirement for a-hydroxysulfonic acid.
[0021] In a preferred embodiment, it has further been found that, by titration of the α-hydroxysulfonic acid salt with strong acid and then reversing the α-hydroxysulfonic acid as its primary components, the acid components can be recovered virtually quantitatively , providing a cost reduction in the reversible acid pretreatment process. When α-hydroxysulfonic acid encounters a basic species, such as a carbonate, the anion salt form of the acid is generated. This acid salt is not reversible as α-hydroxysulfonic acid must be in protonic form to revert to primary components. Since biomass is always accompanied by caustic inorganic materials, it was found that the formation of the anion salt of α-hydroxysulfonic acid represents the greatest “loss” of α-hydroxysulfonic acid in the process of pretreatment with potential reversible acid. It was further found that the acid used for the dehydration step can be conveniently used to titrate the α-hydroxysulfonic acid salt as well and increase the recovery of α-hydroxysulfonic acid by reverting its salt to the acid form and then recovering the acid a- hydroxysulfonic in its primary components. If α-hydroxysulfonic acid cannot be recycled, it is expensive compared to mineral acids. Thus, by recovering a-hydroxysulfonic acid from its acid salt, it provides a cost reduction in the treatment process.
[0022] α-hydroxysulfonic acid is effective for treating biomass that hydrolyzes the biomass to fermentable sugars such as pentosose such as xylose at a lower temperature (eg, about 100°C for α-hydroxymethyl sulfonic acid or acid α-hydroxyethane sulfonic) producing little furfural in the process. It has also been shown that a portion of the cellulose hydrolyzes under these comparatively mild conditions. Other polysaccharides such as starch are also easily hydrolyzed to component sugars by α-hydroxysulfonic acids. Furthermore, α-hydroxysulfonic acid is reversible to readily removable and recyclable materials other than mineral acids such as sulfuric, phosphoric or hydrochloric acid. The lower temperatures and pressures employed in the treatment of biomass lead to a lower equipment cost. The ability to recycle brittle pentose sugars from the end of the pretreatment to the pretreatment entry, without their subsequent conversion to undesirable materials such as furfural, allows for lower consistencies in the pretreatment reaction itself, however still passing a mixture of high consistency solids containing high soluble sugars outside the pre-treatment. Biomass pretreated in this way has been shown to be highly susceptible to further saccharification, especially enzyme-mediated saccharification.
[0023] The a-hydroxysulfonic acids have the general formula
wherein R1 and R2 are individually hydrogen or hydrocarbyl with up to about 9 carbon atoms which may or may not contain oxygen can be used in the treatment of the present invention. Alpha-hydroxysulfonic acid can be a mixture of the aforementioned acids. The acid can generally be prepared by reacting at least one carbonyl compound or carbonyl compound precursor (eg, trioxane and paraformaldehyde) with sulfur dioxide or sulfur dioxide precursor (eg, sulfur and oxidant, or trioxide sulfur and reducing agent) and water according to the following general equation 1.
wherein R1 and R2 are individually hydrogen or hydrocarbyl with up to about 9 carbon atoms or a mixture thereof.
[0024] Illustrative examples of carbonyl compounds useful to prepare the alpha-hydroxysulfonic acids used in this invention are found where R1 = R2 = H (formaldehyde) R1 = H, R2 = CH3 (acetaldehyde) R1 = H, R2 = CH2CH3 ( propionaldehyde) R1 = H, R2 = CH2CH2CH3 (n-butyraldehyde) R1 = H, R2 = CH(CH3)2 (i-butyraldehyde) R1 = H, R2 = CH2OH (glycolaldehyde) R1 = H, R2 = CHOHCH2OH (glyceraldehyde) R1 = H, R2 = C (= O) H (glyoxal)
Ri = H, R2 = I 1 R1 = R2 = CH3 (acetone) R1 = CH2OH, R2 = CH3 (acetol) R1 = CH3, R2 = CH2CH3 (methyl ethyl ketone) R1 = CH3, R2 = CHC(CH3)2 (oxide mesityl) R1 = CH3, R2 = CH2CH(CH3)2 (methyl-i-butylketone) R1, R2 = (CH2)5 (cyclohexanone) or R1 = CH3, R2 = CH2Cl (chloroacetone)
[0025] The carbonyl compounds and their precursors can be a mixture of compounds described above. For example, the mixture can be a carbonyl compound or a precursor such as, for example, trioxane which is known to thermally reverse formaldehyde at elevated temperatures, metaldehyde which is known to thermally reverse to acetaldehyde at elevated temperatures, or an alcohol which may be converted to the aldehyde by dehydrogenating the alcohol to an aldehyde by any known methods. An example of such a conversion to aldehyde from alcohol is described below. An example of a source of carbonyl compounds might be a mixture of hydroxyacetaldehyde and other aldehydes and ketones produced from fast pyrolysis oil as described in "Fast Pyrolysis and Bio-oil Upgrading, Biomass-to-Diesel Workshop", Pacific Northwest National Laboratory, Richland, Washington, September 5-6, 2006. The carbonyl compounds and their precursors can also be a mixture of ketones and/or aldehydes with or without alcohols that can be converted to ketones and/or aldehydes, preferably in the range of 1 to 7 carbon atoms.
[0026] The preparation of a-hydroxysulfonic acids by the combination of organic carbonyl compounds, SO2 and water is a general reaction and is illustrated in equation 2 for acetone.

[0027] α-Hydroxysulfonic acids appear to be as strong as, if not stronger than, HCl since an aqueous solution of the adduct has been reported to react with NaCl releasing the weaker acid, HCl (see US Patent 3549319) .
[0028] The reaction in equation 1 is a true equilibrium, which results in easy reversibility of the acid. That is, when heated, the balance shifts to the starting carbonyl, sulfur dioxide and water (component form). If volatile components (eg, sulfur dioxide) are allowed to exit the reaction mixture through vaporization or other methods, the acidic reaction completely reverses and the solution effectively becomes neutral. Thus, by increasing the temperature and/or reducing the pressure, sulfur dioxide can be expelled and the reaction is completely reversed due to Le Châtelier's principle, the fate of the carbonyl compound is dependent on the nature of the material used. If the carbonyl is also volatile (eg acetaldehyde), this material is also easily removed in the vapor phase. Carbonyl compounds such as benzaldehyde, which are poorly soluble in water, can form a second organic phase and be separated by mechanical means. Thus, the carbonyl can be removed by conventional means, for example, continued application of heat and/or vacuum, steam and nitrogen removal, solvent washing, centrifugation, etc. Therefore, the formation of these acids is reversible in that the temperature is elevated, sulfur dioxide and/or aldehyde and/or ketone can be flash vaporized from the mixture and condensed or absorbed elsewhere to be recycled . These reversible acids, which are approximately as strong as strong mineral acids, are effective in biomass treatment reactions.
[0029] Since acids are effectively removed from the reaction mixture after treatment, base neutralization to complicate downstream processing is substantially avoided. The ability to reverse and recycle these acids also allows for the use of higher concentrations than would otherwise be economically or environmentally practical. As a direct result, the temperature employed in biomass treatment can be reduced to decrease the formation of by-products such as furfural or hydroxymethylfurfural.
[0030] It was found that the equilibrium position given in equation 1 at any given temperature and pressure is highly influenced by the nature of the carbonyl compound used, steric and electronic effects with a strong influence on the thermal stability of the acid. A more steric mass around the carbonyl tends to favor a lower thermal stability of the acid form. Thus, one can adjust the strength of the acid and the temperature of easy decomposition by selecting the appropriate carbonyl compound.
[0031] In one embodiment, the acetaldehyde starting material to produce the alpha-hydroxysulfonic acids can be provided by converting ethanol, produced from the fermentation of the treated biomass of the process of the invention, into acetaldehyde by dehydrogenation or oxidation. Such processes are described in U.S. publication 20130196400 which description is incorporated herein by reference in its entirety.
[0032] As used herein, the term "biomass" means organic materials produced by plants (eg leaves, roots, seeds and stems). Common sources of biomass include: agricultural residues (eg corn stalks, straw, seed husks, sugar cane leaves, sugarcane bagasse, nut husks and manure from cattle, poultry and swine); wood materials (eg wood or bark, sawdust, cut wood and mill scrap); municipal waste (eg used paper and garden scraps); and energy crops (eg poplars, willows, grass, alfalfa, bluegrass, corn, soybeans, seaweed and seaweed). The term “biomass” also refers to the primary building blocks of all of the above, including, but not limited to, saccharides, lignins, celluloses, hemicelluloses and starches. The term "polysaccharides" refers to polymeric carbohydrate structures of repeating units (mono- or disaccharides) joined together by glycosidic bonds. These structures are often linear, but can contain varying degrees of branching. Examples include storage polysaccharides such as starch and glycogen, and structural polysaccharides such as cellulose and chitin.
[0033] As used herein, the term "pentosan" refers to a polysaccharide containing C5 carbohydrate monomeric unit.
[0034] As used herein, the term "carbohydrate" is defined as a compound consisting only of carbon, hydrogen and oxygen atoms, in which the ratio of carbon atoms, hydrogen atoms, to oxygen atoms when converted by hydrolysis in monomeric sugars it is 1:2:1. Well-known examples of carbohydrate include sugars and sugar-derived oligomers and sugar-derived polymers. The term "C5 carbohydrate(s)" refers to any carbohydrate, without limitation, that has five (5) carbon atoms in its monomeric unit. The definition includes pentose sugars of any description and stereoisomerism (eg, D/L aldopentoses and D/L ketopentoses). C5 carbohydrates can include (by way of example and not limitation) xylose, arabinose, litxose, ribose, ribulose and xylulose, in their monomeric and polymeric forms. Polymeric C5 carbohydrates can contain several C5 carbohydrate monomers and in some cases even contain some (minor) amount of C6 carbohydrate monomers. According to the invention, the term "pentose", in addition to chemical compounds of formula C5H10O5, such as xylose or arabinose or mixtures thereof, may also include derivative products including pentose and its derivatives. The term "C6 carbohydrate" refers to any carbohydrate, without limitation, that has six (6) carbon atoms in its monomeric unit. The definition includes hexose sugars of any description and stereoisomerism (eg, D/L aldohexoses and D/L ketohexoses). C6 carbohydrates include (by way of example and not limitation) allose, altrose, fructose, galactose, glucose, gluttony, idose, mannose, psychose, sorbose, tagatose and talose, in their monomeric, oligomeric and polymeric forms. Polymeric C6 carbohydrates can contain several C6 carbohydrate monomers, and in some cases even contain some (lesser) amount of C5 carbohydrate monomers.
[0035] The term "dehydration", as used herein, refers to the removal of a water molecule from a molecule that contains at least one hydroxyl group.
[0036] As used herein, the term "humins" refers to dark, amorphous and undesirable acidic by-products and resinous material resulting from the degradation of sugar and other organic compounds. Humins can also be produced by acidic hydrolysis of carbohydrates. Yang and Sen [Chem. Sus. Chem., Vol. 3. p. 597-603 (2010)] report the formation of humins during the production of fuels from carbohydrates, such as fructose, and speculate that humins are formed by acid-catalyzed dehydration. The molecular weight of the heavy humin components can range from 2.5 to 30 kDa.
[0037] As used herein, the term "miscible" refers to a mixture of components that, when combined, form a single phase (that is, the mixture is "single-phase") under specified conditions (eg, concentrations of the components , temperature).
[0038] As used herein, the term "immiscible" refers to a mixture of components which, when combined, form two or more phases under specified conditions (eg concentrations of components, temperature).
[0039] As used herein, the term "monophasic" refers to a reaction medium that includes only a liquid phase. Some examples are water, aqueous solutions and solutions containing aqueous and organic solvents that are miscible with each other. The term "monophasic" can also be used to describe a method that employs such a reaction medium.
[0040] As used herein, the term "biphasic" refers to a reaction medium that includes two immiscible liquid stages, for example, an aqueous phase and a water-immiscible organic solvent phase. The term "biphasic" can also be used to describe a method that employs such a reaction medium.
[0041] Figure 1 illustrates an embodiment of the present invention for the improved production of furfural from biomass. In this embodiment, a pentosan-containing biomass feedstock ("pentosan-containing biomass feedstock") 112 is introduced into a hydrolysis reaction system 114 along with an optional recycle stream 218 and a recycle stream 318. hydrolysis reaction system 114 can comprise various components including in situ generated α-hydroxysulfonic acid. The term "in situ" as used herein refers to a component that is produced within the total process; it is not limited to a particular reactor for production or use and is therefore synonymous with a component generated in the process. Hydrolysis reaction system 114 can contain one or more reactors and optionally solid or slurry extractors. Reacted product stream 116, containing at least one C5 carbohydrate, at least one α-hydroxysulfonic acid and optionally at least one α-hydroxysulfonic acid salt and solids comprising lignin, cellulose and hemicellulose material is introduced into the acid removal system 120 where the acid is removed in its component form, and then is recovered 122 (and optionally debugged 124) and produces a product stream 126. The recovered acids (in acid form or in component form) are recycled through stream 118 to the hydrolysis reaction system 114. Product stream 126 contains at least one C5 carbohydrate, optionally a C6 carbohydrate, substantially free of the alpha-hydroxysulfonic acids. Optionally, at least a portion of the liquid in product stream 116 containing α-hydroxysulfonic acid can be recycled to hydrolysis reaction system 114 (not shown).
[0042] The second product stream 126 is provided to a separation system 200 where a high solids/liquid mixture ("wet solids") can be separated from the acid removed product stream to form a wet solids stream 220 containing undissolved solids containing cellulose, and a bulk liquid stream 210 which may constitute up to 20 to 95% by weight of the liquid from the product stream removed with acid containing C5 carbohydrates (pentose) and optionally hexose and optionally the acid salt a -hydroxysulfonics. In one embodiment, the cellulose-containing wet solids stream can be further hydrolyzed by other methods, for example, by enzymes to further hydrolyze the biomass to sugar products containing hexose (eg, glucose) and fermented to produce alcohols and acids such as described in US Publication Nos. 2009/0061490, 2012/0122152, 2013/0295629 and US Patent No. 7781191, the descriptions of which are incorporated herein by reference. In another modality, the wet solids stream can be suitably used to generate power by burning the wet solid waste, for example, in a cogeneration boiler. Alternatively, the wet solid product stream can be converted and optionally dried to form granules, which can be used to produce, for example, power in remote locations.
[0043] At least a portion (a second portion) of the bulk liquid stream 210 may optionally be recycled to the hydrolysis reaction system via 218 where the bulk liquid stream comprises more than about 2% by weight, preferably 5% by weight or more, more preferably about 8% by weight or more of C5 carbohydrates and C6 carbohydrates based on the bulk liquid stream. The bulk liquid stream is preferably recycled so as to keep the hydrolysis reaction pumpable, preferably about 20% by weight or less of solids content in the hydrolysis reactor and further accumulate the C5 carbohydrate content of the bulk liquid 210 through recycling. As an embodiment, a portion of the bulk liquid recycle stream 218 can be used to dilute the hydrolysis reaction system 114 for inputting biomass into the hydrolysis reactor in the system and/or to facilitate the extraction of solids in the reactor bottoms (or reactor system output) or can be added to an extractor or to the reactor product stream 116 for dilution.
[0044] A dehydrating acid (mineral acid or organic acid) 135 is introduced into at least a first portion of the bulk liquid stream 216 in a dehydrating step 300 (the dehydrating acid can be added before or during the reaction of dehydration, preferably in solution) in an amount sufficient to titrate the alpha-hydroxysulfonic acid salt, if any, and effectively dehydrate the C5 carbohydrates to form furfural (dehydration reaction) under reaction conditions described herein. The alpha-hydroxy sulfonic acid can optionally be recovered in its component form from this step and then recovered 320 (and optionally scrubbed 124) which can be recycled to the hydrolysis reaction system. The dehydration step 300 takes place in a two-phase reaction medium (contains aqueous phase and water-immiscible organic phase), the aqueous phase being carried out from separation system 200, the organic phase being one or more organic solvents that are substantially immiscible in aqueous phase. The use of an organic solvent with preferred selectivity for furfural extraction extracts furfural from the aqueous phase as it forms during the dehydration reaction. This can improve the total furfural yield. A further advantage is that, by extracting furfural in the organic phase, the unwanted loss of furfural through degradation reactions taking place in the aqueous phase is reduced.
[0045] After the dehydration step 300, the dehydration product stream 310 is transferred to a liquid-liquid extractor 330 for the extraction step, optionally after cooling the stream. Extractor 330 can be operated at a temperature range from about room temperature to about dehydration temperature, as long as the liquid separates into two liquid stages at the temperature of the extractor. The organic phase is separated from the aqueous phase and thus the aqueous recycle stream 318 can be fed directly back to the process loop in the hydrolysis reaction system 114. The aqueous recycle stream 318 will comprise the acidic dehydration catalyst. Depending on the salt, and optionally other organic by-product, content of the aqueous stream, the aqueous recycle stream 318 can be treated to remove unwanted or excessive amounts of salts and/or organic by-products. Preferably, the aqueous recycle stream is subjected to a separation step (not shown). The recovered aqueous recycle stream obtained after treating the aqueous recycle stream is reintroduced into the hydrolysis reaction system 114. Salts and, optionally, other organic by-products, such as humins and acetic acids, are formed as a by-product during one or more of the steps in the process. Typically, part of stream 318 may also be purged from the process to prevent by-product buildup.
[0046] Before going through the liquid-liquid extraction step 330, the dehydration product stream 310 may optionally be routed through a preferably solid/liquid separation step, to remove any humins or other tar that may have been formed. during dehydration step 300, and which may otherwise negatively interfere with the separation of the organic phase from the aqueous phase, or further separation or purification steps 400. The humins or tar will predominantly end up in the solid step and thus will not affect, or to a lesser extent, the subsequent organic/aqueous step 330. The formation of tar, coal and/or humins is a well known problem associated with the production of bio-based products, and their failure to remove them from the production stream can result in problems during the downstream purification and/or separation steps.
[0047] The organic phase is recovered from extraction step 330 as organic product stream 350, containing the target organic compounds such as furfural, furfural derivatives (such as hydroxylmethylfurfural (HMF), methylfurfural) and levulinic acid. Although a portion of the organic product stream 350 can be recycled to the dehydration step (or reactor(s)) 300, the majority of the organic product stream 350 is subjected to a separation step, preferably one or more distillation steps. , in a recovery zone 400. If the extraction solvent is low boiler, it will be removed as a top product, eventually along with water, azeotropic water/furfural mixture and other light organics such as acetic acid. Furfural will then be removed as a 400 bottoms product, optionally with other high boiling impurities such as HMF, levulinic acid or soluble humins. If the extractive solvent is high boiling, it will be removed as 400 bottoms along with other high boiling impurities. Furfural is then removed as a top product, optionally with other low boiling point (AA) impurities and optionally with water, for example, as an azeotropic mixture. Both the 400 overhead and underflow may optionally undergo further purification, for example, by distillation, to remove unwanted impurities from the solvent or furfural. Reaction residual water that was not removed during the liquid-liquid extraction step and which may contain acetic acid or other low boiling impurities is removed from recovery 400 with furfural recovery via stream 420.
[0048] Organic solvents 410 removed/recovered during separation in recovery zone 400 can be recycled back into the process, such as by reintroduction back to dehydration step 300 via an organic recycle stream 410, so as to minimize production costs and maintain process reaction and process efficiency. Alternatively, at least a part of the organic solvents can be directed to an additional solvent purification process such as column distillation/separation or solvent-solvent extraction, before reintroduction back into the production process, in order to remove impurities, mainly humins (heavy by-products) as well as purifying the solvent before reintroduction (not shown). After the solvent purification step, fresh solvent may be added to the purified solvent stream or to the organic recycle stream 410 before reintroduction to the dehydration step 300 or introduced to the dehydration step 300 in order to maintain the required volume of organic phase in the dehydration step.
[0049] Figure 2 shows another embodiment of the present invention for the improved production of furfural from biomass. In this embodiment, a pentosan-containing biomass feedstock ("pentosan-containing biomass feedstock") 112 is introduced into a hydrolysis reaction system 114 along with a recycle stream 218 and an optional aqueous recycle stream 318.
[0050] In another embodiment, a pentosan-containing biomass feedstock ("pentosan-containing biomass feedstock") 112 is introduced into a hydrolysis reaction system 114 along with both the recycle stream 218 and the recycle stream. water recycling 318.
[0051] Although the figures show the dehydrating acid to be introduced at 300, it is also contemplated that the dehydrating acid 135 can be introduced at any point in the process 114, 116, 120, 126, 200, 210, 218, 216, 300, 330 and/or 318.
[0052] Biomass is typically pre-processed to suitable particle sizes which may include milling. Not intending to restrict the scope of the invention, it is typically found easier to process smaller biomass particles. Biomass that is reduced in size to facilitate handling (eg, less than 1.3 cm) are particularly susceptible materials.
[0053] Several factors affect the conversion of the biomass feedstock in the hydrolysis reaction. The carbonyl compound or incipient carbonyl compound (such as trioxane) with sulfur dioxide and water must be added in an amount and under conditions effective to form alpha-hydroxysulfonic acids. The temperature and pressure of the hydrolysis reaction should be in the range to form alpha-hydroxysulfonic acids and hydrolyze the biomass to fermentable sugars. The amount of carbonyl compound or its precursor and sulfur dioxide should be to produce alpha-hydroxysulfonic acids in the range of about 1% by weight, preferably, from about 5% by weight to about 55% by weight, preferably to about 40% by weight, more preferably about 20% by weight, based on the total solution. For the reaction, excess sulfur dioxide is not needed, but any excess sulfur dioxide can be used to boost the balance in eq. 1 to favor the acid form at elevated temperatures. Contact conditions of the hydrolysis reaction can be conducted at temperatures, preferably, at least about 50°C depending on the alpha-hydroxysulfonic acid used, although such temperature may be as low as room temperature depending on the acid and pressure. used. The contact condition of the hydrolysis reaction can be in the range, preferably, up to and including about 150°C depending on the alpha-hydroxysulfonic acid used. In a more preferred condition the temperature is at least about 80°C, more preferably at least about 100°C. In a more preferred condition, the temperature range up to and including about 90°C to about 120°C. Preferably, the reaction is conducted at as low a pressure as possible, given the need to contain excess sulfur dioxide. The reaction may also be conducted at a pressure as low as about 0.1 bar absolute (10 kPa absolute), preferably from about 3 bar absolute (300 kPa absolute), to about a pressure of up to 11 bar absolute (1100 kPa absolute). The temperature and pressure to be optimally utilized will depend on the particular alpha-hydroxysulfonic acid selected and optimized based on economic considerations of metallurgy and containment vessels as practiced by those skilled in the art.
[0054] Numerous methods have been used by those skilled in the art to circumvent these obstacles to mixing, transport and heat transfer. Thus, the weight percentage of biomass solids to total liquids (consistency) can be as low as 1% or more, depending on the selected apparatus and the nature of the biomass (even as high as 33% if the specialized equipment is developed or used). Percent solids is the percentage by weight of solids if the equipment is developed or used). Percent solids is the percentage by weight of dry solids and the % by weight of liquids contains that in biomass. In the preferred embodiment, where more conventional equipment is desired, then the consistency is at least 1 wt%, preferably at least about 2 wt%, more preferably at least about 8 wt%, up to about 25 wt. % by weight, preferably by about 20% by weight, more preferably up to about 15% by weight.
[0055] The temperature of the hydrolysis reaction can be selected so that the maximum amount of extractable carbohydrates is hydrolyzed and extracted as sugar (more preferably pentose and/or hexose) or monosaccharide from the biomass feedstock while the formation of degradation products is limited. The temperatures required for successful pretreatment are controlled by reaction time, solution pH (acid concentration) and reaction temperature. Thus, as the acid concentration is increased, the temperature can be reduced and/or the reaction time prolonged to achieve the same goal. The advantages of lowering the reaction temperature are that the brittle monomeric sugars are protected from degradation to dehydrated species such as furfural and that the lignin sheath is not dissolved or melted and redeposited onto the biomass. If sufficiently high levels of acid are used, temperatures can be reduced below the point where sugar degradation or lignin deposition is problematic; this, in turn, is possible through the use of reversible α-hydroxysulfonic acids. In such a low temperature process it becomes possible to recycle a mixture of sugars from the back of a pretreatment process to the front of a pretreatment process. This allows sugars to create a high steady state value while still handling a pumpable slurry through the pretreatment process. In this process, biomass, water and a-hydroxysulfonic acid are combined in an acid hydrolysis step and are reacted to carry out the biomass pre-treatment. Acids are separated from the reaction mixture as described above and recycled to the pretreatment reactor. A high concentrated solid/liquid mixture (wet solid stream) is then separated from the bulky liquid, which can also be recycled to the reactor. The aqueous phase from the dehydration step is recycled to the hydrolysis step and thus the biomass to liquid ratio is adjusted by the feed ratio of these components and the optimized wet biomass target to move to enzymatic hydrolysis and/or acid catalyzed dehydration .
[0056] In some embodiments, a plurality of reactor vessels can be used to carry out the hydrolysis reaction. These vessels can be of any design capable of carrying out a hydrolysis reaction. Suitable reactor vessel designs may include, but are not limited to, batch, drip bed, concurrent, countercurrent, stirred tank, downflow or fluidized bed reactors. The staging of reactors can be used to arrive at the most economical solution. The remaining biomass feedstock solids can then optionally be separated from the liquid stream to allow more severe processing of the recalcitrant solids or pass directly into the liquid stream for further processing which may include enzymatic hydrolysis, fermentation, extraction, distillation and/or hydrogenation. In another embodiment, a series of reactor vessels can be used with an increasing temperature profile so that a desired sugar fraction is extracted in each vessel. The outlet of each vessel can then be cooled before combining the streams, or the streams can be individually fed to the next reaction for conversion.
[0057] Suitable reactor designs may include, but are not limited to, a back-mixed reactor (eg, a stirred tank, a bubble column and/or a jet mixed reactor) can be used if the viscosity and characteristics of the partially digested biobased feedstock and liquid reaction means are sufficient to operate in a regime where the biobased feedstock solids are suspended in an excess liquid phase (as opposed to a stacked stack digester) . It is also conceivable that a drip bed reactor could be used with the biomass present as the stationary phase and a solution of α-hydroxysulfonic acid passing through the material.
[0058] In some embodiments, the reactions described below are performed in any appropriate design system, including systems comprising continuous flow reactors (such as CSTR and buffer flow reactors), batch, semi-batch or multi-system vessels and reactors of through-flow of filled bed. For strictly economic reasons, it is preferable that the invention be practiced using a continuous flow system in steady state equilibrium. In an advantage of the process in contrast to dilute acid pretreatment reactions in which residual acid is left in the reaction mixture (<1% by weight sulfuric acid), the lower temperatures employed using these acids (5 to 20% by weight) result in substantially lower pressures in the reactor, resulting in potentially less expensive processing systems, such as plastic lined reactors, stainless steel duplex reactors, for example, such as type 2205 reactors.
[0059] The wet solids stream 220 contains at least 5% by weight of undissolved solids containing cellulose, preferably in the range of 12% by weight to about 50% by weight of undissolved solids containing cellulose, preferably in the range of 15% by weight to 35% by weight cellulose-containing undissolved solids and more preferably in the range of 20% by weight to 30% by weight cellulose-containing undissolved solids, based on the wet solid product stream.
[0060] The bulk liquid stream 210 comprises carbohydrate compounds, in particular, it comprises C5 carbohydrates such as pentose. The bulk liquid stream 210 may optionally comprise C6 carbohydrates such as hexose, however, most of the carbohydrates in the bulk liquid stream are C5 carbohydrates, i.e., the bulk liquid stream 210 comprises carbohydrate compounds, of which carbohydrate compounds at least 50% by weight are C5 carbohydrate compounds, based on the total weight of the carbohydrate compounds in the bulk liquid stream 210. The bulk liquid stream may comprise up to 20% by weight to 95% by weight of the liquid contained in the digestion product stream.
[0061] At least a portion of the bulk liquid stream 216 is provided to a dehydration system 300 where the stream is subjected to dehydration reaction conditions, with the addition of a dehydrating acid and additional solvent as appropriate. At least a portion of the bulk liquid stream can be recycled 218 to the hydrolysis reaction system 114, where the bulk liquid stream can be recycled so as to keep the hydrolysis reaction pumpable along with the aqueous recycle stream 318 preferably about 20% by weight or less of solids content in hydrolysis reactor 114. One advantage of recycling part of the bulk liquid stream to hydrolysis reaction system 114 is that the concentration of C5 carbohydrates in the stream of liquid in mass 210 can be increased by keeping the total reaction mixture pumpable without the addition of dilution water. The required make-up water can be introduced into the process system at various locations, as appropriate, to obtain the desired results.
[0062] The dehydration system 300 is a two-phase system for carrying out a dehydration reaction. The use of a two-phase system compared to typical aqueous commercial processes to produce furfural has the advantage that improved furfural yields can be obtained due to in situ extraction of furfural in the organic phase. Furthermore, the use of an aqueous and organic phase allows for more effective separation of furfural from the aqueous phase.
[0063] The dehydration process stream 300 is then introduced into the extraction system (preferably a liquid-liquid extraction system) 330. The aqueous recycle stream 318 is recycled at least in part to the hydrolysis reaction system 114. Organic product stream 350 is then introduced into a separation zone 400, preferably comprising one or more distillation units, so as to produce the desired product, furfural. Optionally, part of the organic product stream 350 can be recycled to dewatering system 300. By recycling part of the organic product stream to dewatering system 300, the furfural concentration in stream 350 can be increased which is beneficial when separating. the furfural form of the organic solvent.
[0064] The acid catalyst used in the dehydration step ("dehydrating acid") can be an organic or inorganic acid (different from α-hydroxysulfonic acids) since it can catalyze the dehydration of C5 carbohydrates to furfural and/or its derivatives. Preferable inorganic acid may include mineral acids, for example, such as HCl, HNO3, H2SO4, H3PO4 and the like. Organic acids can include, for example, acetic acid, formic acid, oxalic acid, levulinic acid, toluenesulfonic acid, citric acid, etc. The dehydrating acid can be provided as such or as part of one or more of the streams supplied to the process.
[0065] The amount of dehydrating acid is preferably in the range of 0.2% by weight, preferably 0.5% by weight, more preferably 0.7% by weight, to 5% by weight, preferably to 2 % by weight, more preferably to 1.5% by weight.
[0066] Since the biomass contains caustic inorganic materials (such as calcium and potassium), we found that the formation of the anion salt of a-hydroxysulfonic acid represents the greatest "loss" of a-hydroxysulfonic acid in the pretreatment process with reversible acid. When α-hydroxysulfonic acid encounters a basic species, such as a carbonate, the anion salt form of the acid is generated. This acid salt is not reversible as α-hydroxysulfonic acid must be in protonic form to revert to primary components.
[0067] We found that by titrating the α-hydroxysulfonic acid salt with strong acid and then reversing α-hydroxysulfonic acid as its primary components, the acidic components can be recovered virtually quantitatively providing a cost reduction in the pre-treatment process with reversible acid. Thus, if maximum recovery of α-hydroxysulfonic acid is desired, the acid catalyst for the dehydration step is preferably a strong acid, such as mineral acid.
[0068] By adding a molar equivalent amount of a mineral acid (such as, for example, hydrochloric, sulfuric or phosphoric acid) to a solution of α-hydroxysulfonic acid salts, a balance between the mineral salt versions can be achieved and protons from acids. By the term around a molar equivalent, the molar equivalent can be ± 20%.
[0069] For example, when the potassium salt of alpha-hydroxyethanesulfonic acid (HESA) is treated with an equivalent of sulfuric acid (a divalent acid), phosphoric (a strong divalent acid) or hydrochloric acid (a monovalent acid), the HESA can be flash evaporated as SO2 and acetaldehyde leaving potassium sulphate, potassium monohydrogen phosphate or potassium chloride in solution. When HESA is recovered at the top, the pH of the saline solution increases to what it was before the addition of mineral acid.
[0070] The reaction (titration) of α-hydroxysulfonic acid salt with strong mineral acid and then reversing α-hydroxysulfonic acid as its primary components is illustrated in equation 3 for the calcium salt of α-hydroxysulfonic acid.

[0071] By adding about a molar equivalent amount of a mineral acid (for example, hydrochloric, sulfuric or phosphoric acid) to a solution of α-hydroxysulfonic acid salts, a balance can be achieved between the protonic and salt versions mineral. Since only α-hydroxysulfonic acid is reversible to volatile components, following Le Chatelier's principle, all the alpha-hydroxysulfonic acid can be recovered and the mineral acid salt is formed.
[0072] It was also found that a-hydroxysulfonic acids can be recovered by part of the mineral acid used as dehydration acid. In such modalities that can generate α-hydroxysulfonic acid salt from the biomass, sufficient acid should preferably be added to carry out the dehydration reaction in addition to the titration.
[0073] Titration can be performed at 300 or performed at 114-120 depending on the location where the dehydrating acid is added. For example, it may be preferable to perform the titration at 114-120 to reduce the amount of salt captured in the wet solid waste 220. This may be one of the advantages of recycling some of the acid in at least a portion of the aqueous recycle stream (via 318).
[0074] The second product stream 126 is transferred to a separation system 200 (solid-liquid separator or phase separator), wherein the wet solids stream 220 comprising solids, and mainly solids comprising cellulose, is separated from the stream. of bulk liquid 210 which contains mainly C5 carbohydrate products such as xylose. Examples of suitable separation methods, for example, may include centrifugal force, filtration, decantation and other similar methods. Optionally, at least a portion of the liquid stream containing the residual α-hydroxysulfonic acid from reaction stream 116 (carbohydrate-containing product stream) can be recycled to the hydrolysis reaction system.
[0075] At least a first portion of the bulk liquid stream is subsequently supplied to a dehydration step for the dehydration of C5 carbohydrates in the bulk liquid product stream, by feeding stream 216 to a dehydration step reaction vessel 300.
[0076] One or both of the streams 210 or 216 can be flash evaporated to remove some of the water (not shown) for the concentrated streams 210 and/or 216. Separation step 200 can be performed in any solid/separation device. suitable liquid such as, but not limited to, filters, centrifuges, screw presses, etc. As mentioned earlier, the liquid stream can optionally be recycled to the hydrolysis step to build up the C5 carbohydrate concentration. Optionally, stream 216 can also be subjected to a flash, distillation or multi-effect evaporator to increase the concentration of C5 carbohydrate.
[0077] The dehydration step 300 takes place in a two-phase mixture of aqueous and organic phases, the aqueous phase being carried out from the separation step 200, the organic phase being one or more organic solvents that are substantially immiscible by the aqueous phase. The use of an organic solvent with preferred selectivity for furfural extraction extracts furfural from the aqueous phase as it forms during the dehydration reaction. This can improve the total furfural yield. A further advantage is that, by extracting furfural in the organic phase, the unwanted loss of furfural through degradation reactions taking place in the aqueous phase is reduced.
[0078] The preferred organic phase for use in the present invention comprises a water-immiscible organic solvent that is substantially immiscible with the aqueous phase containing C5 carbohydrate products. Preferably, such water-immiscible organic solvents have a maximum water solubility of less than about 30% by weight, preferably less than about 10% by weight and more preferably less than about 2% by weight at room temperature. Preferred organic solvents are 1-butanol, sec-butylphenol (SBP), MIBK, toluene and dichloromethane (DCM). Other organic phases can also be used, especially other alcohols, ketones and halogenated alkanes. Thus, for example, organic solvents such as linear or branched alcohols (eg pentanol, tert-butyl alcohol, etc.), cyclic alcohols (eg cyclohexanol), linear or branched alkanones (eg, butanone is, methylethyl ketone (MEK)), pentanone, hexanone, heptanone, diisobutylketone, 3-methyl-2-butanone, 5-methyl-3-heptanone, etc.) and cycloalkanones (eg, cyclobutanone, cyclopentanone, cyclo- hexanone, etc.) can be used in the present invention. Aliphatic and cycloaliphatic ethers (eg, dichloroethyl ether, dimethyl ether, MeTHF), saturated and unsaturated aliphatic or aromatic hydrocarbons (decane, toluene, benzene, cymene, 1-methylnaphthalene), oxygenated hydrocarbons (eg, furan, nonylphenol, etc.). ) and nitroalkanes (eg nitromethane, nitropropane, etc.) can also be used. Likewise, halogenated derivatives of the above-mentioned compounds as well as other halogenated alkanes can also be used as the organic phase (for example, chloromethane, trichloromethane, trichloroethane and the like). Solvents derived from lignin such as Guaiacol, Eugenol, 2-methoxy-4-propylphenol (MPP), 2-methoxy-4-methylphenol (MMP) or a mixture thereof can also be used. Combination of solvents can also be used to fine-tune solvent extractability.
[0079] Preferably, the organic solvent or combination of organic solvents can extract 80% by mol or more of the furfural produced from the aqueous phase, while dissolving less than 1% by weight, even preferably less than 0.1 % by weight, even more preferably less than 0.01% by weight of water.
[0080] The percentage by weight of material in the organic phase is in a suitable range to create a two-phase system with the aqueous phase, for example, from about 5% by weight to about 95% by weight, based on the combined weight the aqueous phase and the organic phase.
[0081] The dehydration process step 300 is carried out for a time period ranging from about 1 minute to about 24 hours, preferably, for a time period ranging from about 5 minutes to about 12 hours, more preferably from about 10 minutes to about 6 hours, even more preferably 30 minutes to 4 hours, even more preferably 30 minutes to 2 hours, or for times within these ranges, at an elevated temperature above about 100°C, including in the range of about 100°C to about 250°C, from about 110°C to 200°C and from about 140°C to about 180°C. One or more dehydrating acids as described above can be added to catalyze the reaction process, preferably mineral acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and the like. The pressure is preferably autogenous hot steam pressure.
[0082] The concentration of C5 carbohydrate compounds in dehydration reactor 300 may vary depending on the product to be obtained. However, according to aspects of the present invention, it has been found that the reaction is optimized for obtaining furfural or other furfural derivatives when the concentration of C5 components during the dehydration process step 300 is between about 0.1% by weight and 20% by weight, more preferably between about 0.2% by weight and 10% by weight, including % based on the weight of the aqueous phase.
[0083] During the step of the dehydration process, at least a part and preferably substantially all of the C5 carbohydrate compounds are converted to furfural. Optionally, other furfural derivatives can also be formed. Due to the nature of furfural, and optionally other furfural derivatives, furfural preferably resides in the organic phase of the biphasic mixture.
[0084] Due to the preference of the formed furfural to reside in the organic phase rather than the aqueous phase at least part of the formed furfural and preferably more than 50% by weight, even more preferably 75% by weight of the formed furfural will dissolve in the organic phase.
[0085] After the dehydration step 300, the dehydration product stream 310 is transferred to an extractor (preferably, liquid-liquid extractor) for the extraction step 330, optionally after cooling the stream. The dehydration product comprises at least a part of the biphasic mixture, comprising an aqueous phase and a water-immiscible organic phase which was present in the reaction vessel during the dehydration process and thus comprises water, organic solvent and further comprises furfural which has been formed by dehydration of C5 carbohydrates. Furfural here will predominantly be dissolved in the organic solvent.
[0086] Extraction 330 can be operated in a temperature range from about room temperature to about dehydration temperature, provided the liquid separates into two liquid stages at the extraction temperature. The organic phase is separated from the aqueous phase, and the thus-obtained aqueous recycle stream 318 can be fed directly back to the process loop for the hydrolysis reaction step. The aqueous recycle stream 318 will comprise the acid catalyst. Depending on the salt, and optionally other organic by-product, content of the aqueous stream, the aqueous recycle stream 318 can be treated to remove unwanted or excessive amounts of salts and/or organic by-products. Preferably, the aqueous recycle stream is subjected to a separation step (not shown). The recovered aqueous recycle stream obtained after treating the aqueous recycle stream is reintroduced to hydrolysis reaction step 114. Salts and, optionally, other organic by-products, such as humins, are formed as a by-product during one or more of the process steps . Typically, part of stream 318 may also be purged 360 from the process to prevent by-product build-up as part of the separation step. Depending on the pH or water content of the aqueous stream, the acid catalyst for the dehydration step (acid dehydration catalyst) can optionally be added before its addition to the hydrolysis reaction or acid dehydration step in order to maintain the total pH of the reaction and the kinetics of the reaction.
[0087] Prior to undergoing the liquid-liquid extraction step, the dehydration product stream 330 may optionally be routed through a separation step, preferably solid/liquid, to remove any insoluble humins or other tar that may have been formed during dehydration step 300 and may otherwise negatively interfere with separation of the organic phase from the aqueous phase, or further separation or purification steps (not shown). The humins or tar will predominantly end up in the solid step and thus will not, or to a lesser extent, affect the subsequent organic/aqueous separation step 330. The formation of tar, coal and/or humins is a well known problem associated with the production of products biobased and their failure to remove them from the production stream can result in problems during downstream purification and/or separation steps.
[0088] The organic phase, that is the organic solvent, is recovered from extraction step 330 as an organic product stream 350, containing the target organic compounds such as furfural and furfural derivatives. Although a portion of the organic product stream can be recycled to dehydration reactor 300, most of the organic product stream 350 is subjected to a separation step, preferably one or more distillation steps, in separation zone 400. Residual water from the reaction that was not removed during the liquid-liquid extraction step and that may contain acetic acid or other water-soluble impurities is removed through a flow stream from separation zone 400, with furfural recovery through the current 420.
[0089] Organic solvents 410 removed/recovered during separation in separation zone 400 can be recycled back to the process, for example, by reintroduction back to dehydration reaction vessel 300, so as to minimize costs of production and maintain the reaction process and process efficiency. Alternatively, at least part of the organic solvent stream 410 can be directed to an additional solvent purification process, such as column distillation/separation or solvent-solvent extraction (not shown), before reintroduction back to the process. production in order to remove impurities, mainly humins (heavy by-products), as well as purify the solvent before reintroduction. After the solvent purification step, fresh solvent may be added to the purified solvent stream prior to reintroduction into the dehydration reaction vessel in order to maintain the required volume of organic phase in the dehydration step.
[0090] The wet solids stream 220 may still contain substantial amounts of residual C5 carbohydrates. In order to extract any residual C5 carbohydrates, the wet solids stream is preferably washed with at least part of the aqueous stream 318 (not shown) before providing the aqueous stream to the hydrolysis system 114.
[0091] In a particular embodiment of the process according to the invention, the wet solids stream 220 can be further treated to produce alcohols and glycols. The cellulose-comprising solids contained in the wet solids stream 220, once separated from the C5 carbohydrate-containing liquid process stream 210 as discussed in detail above, can be subjected to a variety of processes. It is contemplated that wet solids containing cellulose in the wet solids stream 220 (and products separated from it) can be separated as pulp for use in the paper products industry and can also be used to generate alcohols derived from biomass, mono- and diacids biomass derivatives, biomass-derived polyols (polymers), biomass-derived diols, potency and other chemicals useful in industrial manufacturing operations. As explained in more detail hereinafter, cellulose-containing solids can be used from alcohols such as butanol/ethanol or butanediol, for example, via hydrolysis and fermentation. Ethylene glycol and propylene glycol type glycols can be produced by hydrolysis of C6 sugars, but they can alternatively be produced by a catalytic conversion of C6 sugars to diols. Cellulose can also be converted to mono- and diacids such as acetic acid, lactic acid, levulinic acid or succinic acid through fermentation or chemical conversion.
[0092] Solids can also be used to generate power by burning wet solid waste, for example, in a cogeneration boiler. Alternatively, the wet solid product stream can be converted and optionally dried to form granules, which can be used to produce, for example, power in remote locations.
[0093] Examples of biomass-derived diols include, but are not limited to, C2-C10 diols such as ethylene glycol, propylene glycol, 1,4-butanediol (BDO), pentane diol, propylene glycol, 1,2-propanediol, 1 ,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1.5 -pentanediol, 2,3-pentanediol, 2,4-pentanediol and combinations thereof.
[0094] Examples of chemicals that can be produced from the production steps detailed herein include butanol (both n-butanol and isobutanol), mixtures of butanol, HMF (hydroxymethyl) furfural and MMF (5-methoxymethyl furfural).
[0095] Additionally, solids removed during various steps of the process described herein can be converted to power or energy, such as by burning or otherwise treating the solids in a power plant or similar power production facility, to power that can be stored for later sale or used to fuel the closed loop process, thus increasing the efficiency of the process. Solid tar and/or humins can also be converted to a combustible gas, such as by gasification methods to produce fuel gas with low tar content with low emissions and no toxic waste stream or burned as fuel in a boiler.
[0096] Residual α-hydroxysulfonic acid can be removed by applying heat and/or vacuum from a carbohydrate-containing product stream to reverse the formation of α-hydroxysulfonic acid to its starting material to produce a sugar-containing stream fermentable substantially free of α-hydroxysulfonic acid. In particular, the product stream is substantially free of α-hydroxysulfonic acid, which means that no more than about 2% by weight is present in the product stream, preferably no more than about 1% by weight, plus preferably not more than about 0.2% by weight, preferably not more than about 0.1% by weight present in the product stream. The temperature and pressure will depend on the α-hydroxysulfonic acid used and minimizing the temperatures used is desirable to preserve the sugars obtained in the treatment reactions. Typically, removal may be conducted at temperatures in the range of about 50°C, preferably from about 80°C, more preferably from 90°C to about 110°C, to about 150°C. The pressure should be such that the α-hydroxysulfonic acid is flash vaporized into its component form at the temperature to remove the acid. This pressure must be equal to or greater than the pressure of saturated steam at such a temperature, but low enough to cause the α-hydroxysulfonic acid to form its component. For example, the pressure may range from about 0.1 bar absolute (10 kPa absolute) to about 5 bar absolute (500 kPa absolute), more preferably from 0.5 bar absolute (500 kPa absolute) to about 2 bar absolute (200 kPa absolute). It can be recognized by a person skilled in the art that the treatment reaction 114 and the removal of acid 120 may have taken place in the same vessel or in a different vessel or in several different types of vessels depending on the reactor configuration and the staged arrangement since that the system is designed so that the reaction is conducted under conditions favorable for the formation and maintenance of alpha-hydroxysulfonic acid and removal favorable for the reverse reaction (as components). As an example, the reaction in reactor 114 can be operated at approximately 100°C and a pressure of 3 bar absolute (300 kPa absolute) in the presence of alpha-hydroxyethanesulfonic acid and removal vessel 120 can be operated at approximately 110°C and a pressure of 0.5 bar absolute (50 kPa absolute). It is also contemplated that the reversal can be favored by the reactive distillation of the alpha-hydroxysulfonic acid formed. In recycling the removed acid, optionally additional carbonyl compounds, SO2 and water can be added, if necessary. The removed starting material and/or alpha-hydroxysulfonic acid may be condensed and/or purified by contact with water and recycled(s) to reaction system 114 as component(s) or in its recombined form.
[0097] The preferable residence time of the biomass to contact the α-hydroxysulfonic acid in the hydrolysis reaction system may be in the range of about 5 minutes to about 4 hours, more preferably about 15 minutes to about 1 hour .
[0098] In one embodiment, the cellulose-containing product stream may additionally be hydrolyzed by other methods, for example, by enzymes to further hydrolyze biomass to sugar products containing pentose and hexose (eg, glucose) and fermented to produce alcohols such as described in US Publication No. 2009/0061490 and US Patent No. 7781191, the descriptions of which are incorporated herein by reference.
[0099] The term "fermentable sugar" refers to oligosaccharides and monosaccharides that can be used as a carbon source (eg pentoses and hexoses) by a microorganism in a fermentation process. In an enzymatic hydrolysis fermentation process, the pH of the wet solids stream can be adjusted to be within a range that is ideal for the cellulase enzymes used. Generally, the pH of the pretreated feedstock is adjusted within a range of about 3.0 to about 7.0, or any pH in between.
[00100] The temperature of the treated feed load is adjusted to be within the optimal range for the activity of cellulase enzymes. Generally, a temperature of about 15°C to about 100°C, about 20°C to about 85°C, about 30°C to about 70°C, preferably, or any temperature in between, is suitable for most cellulase enzymes. Cellulases, β-glucosidase and other accessory enzymes necessary for cellulose hydrolysis are added to the pretreated feedstock, before, during or after adjusting the temperature and pH of the aqueous slurry after pretreatment. Preferably, enzymes are added to the pretreated lignocellulosic feedstock after adjusting the temperature and pH of the slurry.
[00101] By the term "cellulase enzymes" or "cellulases" is meant a mixture of enzymes that hydrolyze cellulose. The mixture may include cellobiohydrolases (CBH), glucobiohydrolases (GBH), endoglucanases (EG), glycosyl hydrolase family 61 proteins (GH61) and β-glucosidase. By the term "β-glucosidase" is meant any enzyme that hydrolyzes the glucose dimer, cellobiose, glucose. In a non-limiting example, a cellulase mixture can include EG, CBH, GH61 and β-glucosidase enzymes.
[00102] Enzymatic hydrolysis can also be carried out in the presence of one or more xylanase enzymes. Examples of xylanase enzymes that can also be used for this purpose include, for example, xylanase 1, 2 (Xyn1 and Xyn2) and β-xylosidase, which are typically present in cellulase mixtures.
[00103] The process can be performed with any type of cellulase enzymes, regardless of their source. Non-limiting examples of cellulases that can be used include those obtained from fungi of the genera Aspergillus, Humicola and Trichoderma, Myceliophthora, Chrysosporium and from bacteria of the genera Bacillus, Thermobifida and Thermotoga. In some embodiments, the filamentous fungal host cell is a cell from Acremonium, Aspergillus, Aureobasidium, Bjerkandera, Ceriporiopsis, Chrysosporium, Coprinus, Coriolus, Cryptococcus, Filibasidium, Fusarium, Humicola, Magnaporthe, Mucor, Neocalliophixthora, Myceliophthora, , Phanerochaete, Phlebia, Piromyces, Pleurotus, Schizophyllum, Talaromyces, Thermoascus, Thielavia, Tolypocladium, Trametes or Trichoderma.
[00104] The dosage of the cellulase enzyme is chosen to convert the cellulose from the pretreated feedstock into glucose. For example, a suitable dosage of cellulase can be about 1 to about 100 mg of enzyme (dry weight) per gram of cellulose.
[00105] In practice, hydrolysis can be carried out in a hydrolysis system, which can include a series of hydrolysis reactors. The number of hydrolysis reactors in the system depends on the cost of the reactors, the volume of aqueous suspension, and other factors. Enzymatic hydrolysis with cellulase enzymes produces an aqueous sugar stream (hydrolysate) comprising glucose, unconverted cellulose, lignin and other sugar components. The hydrolysis can be carried out in two stages (see U.S. Patent No. 5,536325, which is hereby incorporated by reference), or it can be carried out in a single stage.
[00106] In the fermentation system, the aqueous sugar stream is then fermented by one or more of a fermentation microorganism to produce a fermentation broth comprising the alcoholic fermentation product useful as biofuels. In the fermentation system, any one of several known microorganisms (eg yeast or bacteria) can be used to convert sugar into ethanol or other alcoholic fermentation products. Microorganisms convert sugars, including but not limited to glucose, mannose and galactose present in the clarified sugar solution to a fermentation product.
[00107] Many known microorganisms can be used in the present process to produce the desired alcohol for use in biofuels. Clostridia, Escherichia coli (E. coli) and recombinant strains of E. coli, genetically modified strain of Zymomonas mobilis as described in US 2003/0162271, US Patent No. 7741119 and US Patent No. 7741084 (whose descriptions are incorporated herein by reference) are some examples of such bacteria. The microorganisms can also be a yeast or a filamentous fungus of a genus Saccharomyces, Kluyveromyces, Candida, Pichia, Schizosaccharomyces, Hansenula, Kloeckera, Schwanniomyces, Yarrowia, Aspergillus, Trichoderma, Humicola, Acremonium, Fusarium and Penicillium. Fermentation can also be carried out with recombinant yeast developed to ferment hexose and pentose sugars to ethanol. Recombinant yeasts which can ferment one or both of the sugars of pentose xylose and arabinose to ethanol are described in US Patent No. 5,789,210, US Patent No. 6475768, European Patent EP 1727890, European Patent EPI 863901 and WO 2006/096130 which descriptions are incorporated herein by reference. Xylose utilization may be mediated through the xylose reductase/xylitol dehydrogenase pathway (eg WO9742307 A1 19971113 and WO9513362 A1 19950518) or the xylose isomerase pathway (eg WO2007028811 or WO2009109631). It is also contemplated that the fermentation organism may also produce fatty alcohols, for example, as described in WO 2008/119082 and PCT/US07/011923 which description is incorporated herein by reference. In another embodiment, fermentation can be carried out by yeast capable of predominantly fermenting C6 sugars, for example, using commercially available strains such as Thermosacc and Superstart.
[00108] Preferably, the fermentation is carried out at or near the ideal temperature and pH of the fermentation microorganism. For example, the temperature can be from about 25°C to about 55°C, or any amount in between. The dose of the fermentation microorganism will depend on other factors such as the activity of the fermentation microorganism, the desired fermentation time, reactor volume and other parameters. It will be recognized that these parameters can be adjusted as desired by one skilled in the art to achieve optimal fermentation conditions.
[00109] The fermentation can be conducted in batch, continuous or batch-fed modes, with or without agitation. The fermentation system can employ a variety of fermentation reactors.
[00110] In some embodiments, the hydrolysis system and the fermentation system can be conducted in the same vessel. In one embodiment, the hydrolysis can be partially completed and the partially hydrolyzed stream can be fermented. In one embodiment, a simultaneous saccharification and fermentation (SSF) process where the hydrolysis system can be run until the target solids percentage is reached and then the hydrolyzed biomass can be transferred to a fermentation system.
[00111] The fermentation system produces an alcohol stream that preferably contains at least one alcohol having 2 to 18 carbon atoms. In the recovery system, when the product to be recovered in the alcohol stream is a distillable alcohol, such as ethanol, the alcohol can be recovered by distillation in a manner known to separate such alcohol from an aqueous stream. If the product to be recovered in the alcohol stream is not a distillable alcohol, such as fatty alcohols, the alcohol can be recovered by removing the alcohols as solids or as oils from the fermentation vessel, thus separating from the aqueous effluent stream.
[00112] Although the invention is susceptible to various modifications and alternative forms, its specific embodiments are shown by way of examples described in detail herein. It is to be understood that the detailed description is not intended to limit the invention to the particular form described, but rather is intended to cover all modifications, equivalents and alternatives that fall within the spirit and scope of the present invention as defined in the appended claims. The present invention will be illustrated by the following illustrative embodiment, which is provided for illustration only and is not to be construed as limiting the claimed invention in any way. ILLUSTRATIVE MODALITIES General methods and materials
[00113] In the examples, the aldehyde or aldehyde precursors were obtained from Sigma-Aldrich Co. α-hydroxyethane sulfonic acid (HESA) was prepared according to US2012/0122152. Biphasic Dehydration
[00114] The dehydration of biphasic acid from C5 carbohydrates (mainly xylose) in aqueous streams of Examples 1 and 2 below was carried out in a 500 ml zipperclave reactor (Autoclave Engineers, Inc.) and/or a 300 ml Parr autoclave . In a typical operation, H2SO4 is added on a weight basis at the required concentration to the aqueous C5 carbohydrate feed stream along with an immiscible organic solvent with a certain ratio of aqueous:organic compound to weight. The reactor is then heated to the reaction temperature and maintained at that temperature for the residence time indicated in the examples. After the reaction was completed, the reaction mixture was weighed and transferred to a separatory funnel to allow two liquid phases to separate. After separation, each layer was weighed and analyzed for its content. The aqueous layer was analyzed using HPLC and the organic layer was analyzed using GC as described below. analytical methods
[00115] The aqueous layers of acid dehydration operations were analyzed and quantified for various components such as glucose, xylose, arabinose, mannose, formic acid, acetic acid, levulinic acid, furfural using the high performance liquid chromatography (HPLC) system (Shimadzu) equipped with a refractive index detector (Shimadzu) on a BIO-RAD 87H column. Before injection, samples were filtered through 0.45 μm HV filters (Millipore, Bedford, MA, USA) and a volume of 10 μL was injected. The mobile phase for the column was 5 mM H2SO4 in Milli-Q water at a flow rate of 0.6 mL/min.
[00116] In a typical two-phase dewatering operation, the concentration of furfural in the organic phase or layer was measured using GC. The Agilent 6890 CG with a DB-1301 capillary column installed in its split/splitless inlet was used with the FID. Column parameters were 30 m long, 0.25 mm internal diameter and 1.0 μm film thickness. The method parameters were as follows: Temp Program. Oven- 40°C 3 Min Hold, 10°C/min Ramp to 280°C 3min Hold Inlet Temperature 250°C, Injection Volume 1.0 μl, Split Ratio 100:1, Constant Pressure 20 psi (2000 kPa) of Helium Carrier Gas Temp. Detector 325°C, H2 flow 35 ml/min, air 400 ml/min and Helium composition 25 ml/min Calculations Xylose Conversion = {[mol of Xylose]feed - [mol of Xylose]AL}/[mol of Xylose]feed Furfural Selectivity = {[moles of FUR]AL + [moles of FUR]OL}/{[moles of Xylose]feed - [moles of Xylose]AL} Furfural Yield = Xylose Conversion * Furfural Selectivity Where FUR = Furfural, AL = aqueous layer or phase and OL = organic layer or phase. Example 1: Hydrolysis with α-hydroxyethane sulfonic acid (HESA) - Stream 1
[00117] In a 1 gallon (3.78 L) C276 Parr reactor equipped with in situ IR optics was added approximately 350 grams of corn stubble characterized by the composition [dry basis: 24% by weight xylan; 33% by weight glucan, 16% by weight moisture] chopped into 0.5 cm nominal particles. To this was added approximately 2600 grams (runs 1-3) and 2200 g (runs 4-6) of 5% by weight. α-hydroxyethane sulfonic acid (HESA) prepared by diluting a 40% by weight loading solution of the acid, recycled acid from vaporization of components at the end of a reaction cycle, excessive press liquid from bottoms after pressing the undissolved down to about 20-22% by weight. Runs 1-3 bleached about 11% by weight of fresh dried corn stubble to start an run, while runs 4-6 bleached about 13% by weight. The target acid concentration was confirmed by proton NMR of the starting mixture which integrates over the peaks for water and acid. The top of the reactor with a 4-blade downward pitch impeller was placed on top of the reaction vessel and the reactor was sealed. The integrity of the reactor system pressure and the replacement of the air atmosphere was achieved by pressurizing with nitrogen to 100 psig (689.5 kPa gauge), where the sealed reactor was maintained for 15 minutes with no pressure loss followed by ventilation in atmospheric pressure. IV acquisition was started and the reaction mixture was shaken at 500 rpm. The reactor was then heated to 120°C and kept at a target temperature for 60 minutes. During this time period, the in situ IV describes the presence of HESA, SO2 and acetaldehyde in an equilibrium mixture. An increase in sugars is evident in the IR spectra, with an increase in the height of the typical xylose and glucose band being apparent. At the end of the reaction period, acid inversion was achieved by opening the reactor gas cap to a top condensing system for acid recovery and simultaneously adjusting the reactor temperature setpoint to 100°C. Reactor vaporization rapidly cools the reactor contents to the 100°C setpoint. The top condensing system consisted of a 1 liter jacketed flask equipped with a fiber optic based IR probe, a dry ice acetone condenser at the outlet and incoming gas through a steel condenser. 18” long made from a ^” diameter C-276 core installed inside ^” stainless steel tubing with proper fittings to achieve a shell-in-tube condenser draining down into the recovery bottle. The recovery bottle was charged with approximately 400 grams of DI water and the condenser and jacketed bottle cooled with a circulating fluid held at 1°C. The progress of acid reversal was monitored through the use of IV in situ in the Parr reactor and in the top condensing flask. During reversal, the first component to leave the Parr reactor was SO2 followed quickly by a decrease in bands for HESA. Correspondingly, bands for SO2 increase in the recovery vial and then fall rapidly as HESA is formed from the combination of vaporized acetaldehyde with this component. The reversal was continued until the in situ IV of the Parr reactor did not show any remaining traces of α-hydroxyethane sulfonic acid. The top-end products IV described that the HESA concentration at that point had reached a maximum and then began to decrease due to dilution with condensed water, free of α-hydroxyethane sulfonic acid components, building up in the recovery bottle. The reaction mixture was then cooled to room temperature, opened and the contents were filtered through a Buchner funnel with medium filter paper using a vacuum aspirator to remove the liquid through the funnel. The wet solids are transferred from the Buchner funnel and placed in a filter press where an additional portion of liquid is pressed from the solids to create a high consistency biomass mixture (about 22% undissolved solids by weight) . The dry weight of solid is determined by washing a portion of the solids with water and then oven drying to a constant weight. A small portion of the combined liquid filtrate and press is removed for analysis by HPLC, NMR and elemental analysis via XRF; the rest is reserved for the next cycle with fresh biomass. A recycling experiment is carried out by combining the primary filtrate and pressing liquids with a sufficient amount of HESA, either recycled from the top products from the previous run or fresh acid from a 40% by weight filler solution. , and water to yield 2200 to 2600 grams of a 5% by weight acid solution which is returned to a 1 gallon (3.78 L) C276 Parr reactor where it is mixed with another 350 gram portion of fresh biomass. The pretreatment, ventilation and recovery and filtration cycle were repeated five times in addition to the initial start-up operation to produce the sample used in further experiments. HPLC analysis of the press is given below in Stream 1 (Table 1). Example 2: Hydrolysis with a-hydroxyethanesulfonic acid (HESA) - streams 2 and 3
[00118] In a 7 gallon (26.4 liters) stainless steel 316 batch circulation digester, approximately 1820 grams (29.14% by weight moisture) of corn stubble characterized by composition [dry base: xylan 17 .7% by weight; glucan 33% by weight] minced into nominal 2 inch particles. A target ratio of fresh dry solids to liquids being 9: 1 being targeted for each run. The material has been placed in a basket and is fixed during operation while the liquid is circulated. Solids are removed at the end of the operation after a free liquid drain and pressed to remove additional liquid. 1820g fresh stubble (1290.5g dry), 1452g 40% by weight α-hydroxyethanesulfonic acid (HESA) loading solution, 2984g make-up water and 7549g recycle press (make-up water in stream 1). The reactor was brought to 120°C in about 10 minutes and held for 1 hour. The reactor was then vented to remove the acid mass in a caustic scrubber. The acid was not recycled for this study and was made from the charge solution for each operation. Two streams were produced (Current 2 and 3) generated by this procedure with different concentrations of xylose and analyzed as indicated in Table 1. Example 3: Biomass Digestion to Extract Xylan in the Form of Xylose and Furfural For acid dehydration operations, were obtained three streams containing various concentrations of xylose (as indicated in Table 1) using a pressure-reversible acid digestion step. Subsequently, acid dehydration operations were carried out by charging 100 g of an aqueous stream of xylose with H 2 SO 4 acid added to 1% by weight together with an equal amount of organic extracting solvent such as sec-butyl phenol (SBP). The reactor was then heated to 170°C and the temperature was maintained for a total time of 1 h from heating. After the reaction is complete, the reactor is cooled to room temperature and the two liquid stages are separated. The aqueous layer was analyzed using HPLC and organic layer using GC for its content. The amount of xylose conversion and selectivity to furfural is shown in Figure 2.

[00119] The results in Figure 3 show that the conversion of xylose from the pressure-reversible acid-derived current to produce furfural. In all cases, furfural selectivities greater than 50% were observed with varying concentrations of xylose in the feed. Example 4: Furfural Production Using Variable Acid Concentration
[00120] Various concentrations of acid were tested for conversion of xylose to furfural. In a typical run, 100 g of 5% by weight xylose solution (which can be assumed to be produced via digestion) was prepared along with various concentrations of acid as shown in Figure 4. Equal amount (100 g) of Sec butylphenol (organic solvent) is added to the reactor to create a two-phase reaction medium. The reactor was then heated to 170°C and samples were taken several times to measure furfural yield. After the reaction is completed, the reactor is cooled to room temperature and the two liquid phases are separated. The aqueous layer was analyzed using HPLC and organic layer using GC for its content. Furfural yield from operations is shown in Figure 4.

权利要求:
Claims (15)
[0001]
1. Method for producing furfural from pentosan-containing biomass material comprising: (a) providing a pentosan-containing biomass, and characterized in that it comprises the steps of: (b) contacting the biomass with a solution containing at least one acid α-hydroxysulfonic, thereby hydrolyzing the biomass to produce a product stream containing at least one C5 carbohydrate compound in monomeric and/or oligomeric form, and α-hydroxysulfonic acid; (c) separating at least a portion of the α-hydroxysulfonic acid from the product stream containing at least one C5 carbohydrate compound to provide an acid-removed product stream containing the at least one C5 carbohydrate compound and recovering the α-hydroxysulfuric acid in its component form; (d) separating a liquid stream containing said at least one C5 carbohydrate compound and a wet solid stream containing remaining biomass from the acid-removed product; (e) dehydrating the C5 carbohydrate compound in at least a first portion of the liquid stream in the presence of a dehydrating acid, in a two-phase reaction medium comprising an aqueous phase and a water-immiscible organic phase, at a temperature in the range of 100 °C to 250 °C; (f) separating an organic phase stream containing furfural and an aqueous stream containing the acid from the dehydration product stream; (g) recycling at least a portion of the aqueous stream or a second portion of the liquid stream to step (b); (h) recovering furfural from the organic phase stream.
[0002]
2. Method according to claim 1, characterized in that the amount of dehydrating acid is in the range of 0.2% by weight to 5% by weight, based on the liquid stream, preferably the amount of dehydrating acid is in the range of 0.5% by weight to 2.0% by weight, based on the liquid stream, more preferably the amount of dehydrating acid is in the range of 0.7% by weight to 1 .5% by weight, based on the liquid stream.
[0003]
3. Method according to claim 1, characterized in that the dehydration step is carried out at a temperature in the range of 140°C to 250°C.
[0004]
4. Method according to claim 1, characterized in that: (i) at least a second portion of the liquid stream from step (d) is recycled to step (b); (ii) at least a portion of the aqueous stream from step (f) is recycled to step (b); or, (iii) at least a portion of the aqueous stream from step (f) and a second portion of the liquid stream from step (d) are recycled to step (b).
[0005]
5. Method according to claim 1, characterized in that at least a portion of the organic phase stream after furfural recovery is recycled to step (e) to provide the two-phase reaction medium.
[0006]
6. Method according to claim 5, characterized in that the organic phase stream after furfural recovery is purified before recycling to step (e).
[0007]
7. Method according to claim 1, characterized in that step (b) is carried out at a temperature in the range of 50°C to 150°C and at a pressure in the range of 0.1 bar absolute (10 kPa absolute) at 11 bar absolute (1100 kPa absolute).
[0008]
8. Method according to claim 1, characterized in that: (i) the dehydrating acid is a mineral acid or an organic acid; (ii) the dehydrating acid is a mineral acid, where the mineral acid is selected from the group consisting of sulfuric acid, phosphoric acid, hydrochloric acid and mixtures thereof; or, (iii) the dehydrating acid is an organic acid, where the organic acid is selected from the group consisting of acetic acid, formic acid, oxalic acid, levulinic acid, citric acid and mixtures thereof.
[0009]
9. Process according to claim 1, characterized in that the liquid stream separated from the wet solid stream comprises C5 carbohydrate in a concentration ranging from 0.1% by weight to 15% by weight.
[0010]
10. Method according to claim 1, characterized in that the dehydrating acid is a mineral acid selected from the group consisting of sulfuric acid, phosphoric acid, hydrochloric acid and mixtures thereof, and in which to recover a-hydroxysulfonic acid from an α-hydroxysulfonic acid salt formed in step (b) in its component form.
[0011]
11. Method according to claim 5, characterized in that the separation in step (c) is carried out at a temperature in the range of 50°C to 150°C and at a pressure in the range of 0.1 bar absolute ( 10 kPa absolute) at 5 bar absolute (5500 kPa absolute).
[0012]
12. Method according to claim 1, characterized in that at least a portion of the aqueous stream from step (f) is contacted with the wet solid stream prior to recycling to step (b).
[0013]
13. Method according to claim 1, characterized in that the α-hydroxysulfonic acid is present in an amount ranging from 1% by weight to 55% by weight, based on the solution.
[0014]
14. Method according to claim 1, characterized in that: (i) the a-hydroxysulfonic acid is produced from (a) a carbonyl compound or a precursor of a carbonyl compound with (b) carbon dioxide sulfur or a precursor of sulfur dioxide and (c) water; or, (ii) the α-hydroxysulfonic acid is generated in situ.
[0015]
15. Method according to claim 1, characterized in that it recycles at least a portion of the aqueous stream and a second portion of the liquid stream to step (b).

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同族专利:

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WO2016025678A1|2016-02-18|

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BR112016030664A2|2017-08-22|

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CA2954306A1|2016-02-18|

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法律状态:
2019-08-27| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-04-20| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-06-29| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 13/08/2015, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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US201462037190P| true| 2014-08-14|2014-08-14|

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US62/037,190|2014-08-14|

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PCT/US2015/044990|WO2016025678A1|2014-08-14|2015-08-13|Process for preparing furfural from biomass|

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