RU2807479C1 - Methods for producing multiple valuable flows from biomass-based sources - Google Patents

Abstract

FIELD: biotechnology.

SUBSTANCE: methods for processing plant biomass. A method is proposed for obtaining at least two target products - target alditols and target glycols as conjugated products, including: providing a mixed stream of monomeric sugars C5 and C6 obtained from decomposed raw materials based on plant biomass; continuous hydrogenation of a mixed stream of C5 and C6 monomer sugars to form a mixed stream of C5 and C6 alditols; separating the first target product - the target alditol or the target mixture of alditols, from the mixed stream of C5 and C6 alditols with discarding the residual mixed stream of C5 and C6 alditols; continuous hydrogenolysis of the residual mixed stream of C5 and C6 alditols to form a mixed stream of C2-C4 glycols; and isolating the second target product - the target glycol or the target mixture of glycols, from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product is either the target alditol/target alditol mixture or the target glycol/target mixture of glycols, and the first target product is isolated by crystallization.

EFFECT: highly efficient, low-complexity process with improved production agility, reduced waste and higher overall yield compared to traditional alditol or glycol processes.

9 cl, 3 dwg, 6 tbl, 9 ex

Description

BACKGROUND OF THE ART

Processing biomass-derived hemicellulose hydrolysates to produce specific alditols is complex, inefficient, and expensive. For example, there are great difficulties in achieving significant extraction yields of high purity aldite when using feedstocks based on hemicellulosic starting material. Cascading losses associated with various purification and separation unit operations, along with other process steps performed in the prior art, are continually observed, resulting in reduced efficiency and reduced aldite recovery volumes. Currently, sorbitol is produced from a single stream of C6 sugars, typically hydrogenated corn glucose, while xylitol is produced from a single stream of C5 sugars derived from larch or poplar trees. There remains a need in the art for a process that can use mixed C5/C6 sugar streams derived from various unsorted hemicellulosic feedstocks to recover the corresponding target C5/C6 alditols in addition to the target C2-C4 glycols as needed.

Indeed, there remains a need in the art for an efficient and highly productive process aimed at recovering high purity alditols and other desired conjugate products derived from various biomass while minimizing the inefficiencies and losses associated with further downstream operations.

SUMMARY OF THE INVENTION

In one embodiment, the method includes optimizing the overall recovery of the products without maximizing the recovery of each product individually, wherein the products are a target alditol or target mixture of alditols and a target glycol or target mixture of glycols. The method includes hydrogenation of a mixed stream of monomeric C5/C6 sugars to form a mixed stream of C5/C6 alditols; separating the target aldite or target alditol mixture from the mixed C5/C6 alditol stream, discarding the residual mixed C5/C6 alditol stream; hydrogenolysis of the residual mixed stream of C5/C6 alditols to form a mixed stream of C2-C4 glycols; and isolating the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product is either the target alditol/target alditol mixture or the target glycol/target glycol mixture.

In another embodiment, the method includes optimizing the overall recovery of the products without maximizing the recovery of each product individually, wherein the products are xylitol and a target glycol or a target mixture of glycols, the method comprising: hydrogenating a mixed stream of monomeric C5/C6 sugars with the formation of a mixed stream of C5/C6 alditols; separating xylitol from the mixed C5/C6 alditol stream and discarding the residual mixed C5/C6 alditol stream; hydrogenolysis of the residual mixed stream of C5/C6 alditols to form a mixed stream of C2-C4 glycols; and isolating the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product consists of either xylitol or the target glycol or the target mixture of glycols.

In yet another embodiment, the method includes a synergistic improvement in the overall recovery of the products without the need to change the overall recovery of each product individually, wherein the products are a target monomeric C5/C6 sugar or a target mixture of monomeric C5/C6 sugars and a target glycol or a target mixture of glycols, the method comprising isolating a target monomeric C5/C6 sugar or a target mixture of monomeric C5/C6 sugars from a mixed stream of monomeric C5/C6 sugars to form a residual mixed stream of monomeric C5/C6 sugars; hydrogenolysis of the residual mixed stream of monomeric C5/C6 sugars to form a mixed stream of C2-C4 glycols; and isolating the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product is either the target monomeric C5/C6 sugar/target mixture of monomeric C5/C6 sugars or the target glycol/target mixture of glycols.

In another embodiment, the method includes hydrogenating a stream of monomeric sugars to form a mixed alditol stream; recovering the target aldite or target aldite mixture from the mixed aldite stream, discarding the remaining mixed aldite stream; and hydrogenolysis of the residual mixed alditol stream to form a mixed stream of C2-C4 glycols.

In another embodiment, the method includes hydrogenating a stream of monomeric sugars to form a mixed alditol stream; recovering the target aldite or target aldite mixture from the mixed aldite stream, discarding the remaining mixed aldite stream; hydrogenolysis of the residual mixed alditol stream to form a mixed stream of C2-C4 glycols; and recovering the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols.

In another embodiment, the method includes hydrogenating a mixed stream of C5/C6 monomeric sugars to form a mixed stream of C5/C6 alditols; recovering the target aldite or target alditol mixture from the mixed C5/C6 alditol stream, discarding the residual mixed C5/C6 alditol stream; and hydrogenolysis of the residual mixed stream of C5/C6 alditols to form a mixed stream of C2-C4 glycols.

In another embodiment, the method includes hydrogenating a mixed stream of C5/C6 monomeric sugars to form a mixed stream of C5/C6 alditols; recovering the target aldite or target alditol mixture from the mixed C5/C6 alditol stream, discarding the residual mixed C5/C6 alditol stream; hydrogenolysis of the residual mixed stream of C5/C6 alditols to form a mixed stream of C2-C4 glycols; and recovering the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols.

In another embodiment, the method includes recovering at least one target monomer sugar from the mixed monomer sugar stream while discarding the remaining mixed monomer sugar stream; hydrogenating the recovered target monomer sugar to form at least one target alditol; hydrogenating at least a portion of the residual mixed monomer sugar stream to form a mixed alditol stream; and hydrogenolysis of the mixed stream of alditols to form a mixed stream of C2-C4 glycols.

In another embodiment, the method includes selecting a target alditol or target mixture of alditols, continuously hydrogenating a mixed stream of C5/C6 monomeric sugars to form a mixed stream of C5/C6 alditols; separating the target aldite or target alditol mixture from the mixed C5/C6 alditol stream, discarding the residual mixed C5/C6 alditol stream; continuous hydrogenolysis of the residual mixed stream of C5/C6 alditols to form a mixed stream of C2-C4 glycols; and isolating the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product is either the target alditol/target alditol mixture or the target glycol/target glycol mixture.

As used herein, the term “alditol” will be synonymous with the terms “polyhydric alcohol,” “sugar polyol,” and “sugar alcohol.” "Arabite", "arabin", "arabinite" and "liksit" are synonymous. Exemplary alditols prepared using the described methods include xylitol, sorbitol, and the like. Exemplary five-carbon (C5) alditols include arabitol, ribitol, and xylitol. Exemplary six-carbon (C6) alditols include allite, galactitol, iditol, mannitol, sorbitol, and tallitol. "C5/C6 alditol" includes a mixture of alditols characterized by any ratio of C5 to C6 alditol. “C5/C6 monomer sugar” means a mixture of monomeric sugars (i.e., monosaccharides) characterized by any ratio of a five-carbon (C5) monosaccharide (pentose) to a six-carbon (C6) monosaccharide (hexose). Exemplary C5 and C6 monosaccharides include monosaccharide derived from plant biomass, specifically arabinose, lyxose, ribose, ribulose, xylose and xylulose, and C6 sugars such as fructose and glucose.

"Glycol" means a molecule containing two hydroxyl (OH) groups attached to different carbon atoms. “Glycols with two carbon atoms (C2), three carbon atoms (C3) and four carbon atoms (C4)” include ethylene glycol, propylene glycol and butanediol isomers, respectively.

As used herein, the terms “comprising” (also “includes”, etc.), “having”, and “including” are inclusive (open) and do not exclude additional, unspecified elements or process steps. All elements appearing in the singular may also be used in the plural unless the context clearly dictates otherwise. The ends of all ranges of the same characteristics or components are independently combined and include the specified endpoints. The term "combination thereof" includes two or more components of the list. The term "homogeneous" refers to a homogeneous mixture of components. The terms "first", "second", "and the like", "primary", "secondary" and the like are not used herein to indicate any order, quantity or importance, but rather are used to distinguish one element from another. The designation “N/A” used in the tables means not provided; the designation “ND” means not determined; and the designation "TR" means in trace amounts.

BRIEF DESCRIPTION OF GRAPHIC MATERIALS

The accompanying graphics are included and form part of the description:

Fig. 1 is a flow diagram of an exemplary method for a biomass pre-treatment step (20), comprising: decomposing (1) biomass from biomass-based feedstock (100), separating (2) the biomass into fractions, (3) lignin recovery, converting hemicellulose oligomers to monosaccharides (4) and optional isolation (5) of monosaccharides.

Fig. 2 is a process flow diagram for the separation and crystallization step (40), including extraction (10) of the target alditol from the hydrogenation feed stream (30), extraction (11) of the alditol with increased efficiency, extraction (12) of other alditols, and addition (13 ) missing amount of aldites.

Fig. 3 is a process flow diagram for the hydrogenolysis and separation step (50), including hydrogenolysis (14) and glycol separation processes (15).

DETAILED DESCRIPTION

Surprisingly synergistic and advantageous methods are described herein for the recovery of alditols and/or glycols from various hemicellulose-containing biomass. Traditional xylitol production typically focuses on the single extraction of xylitol from a single feed stream, where extraction is complex, costly and uneconomical, and high purity is difficult to achieve due to high levels of non-xylose aldose organics such as lignin and ash. Much of the global xylitol industry, for example, predominantly uses corn cobs or larch/poplar-based xylose feedstocks, which require extensive purification processing to carry out hydrogenation steps to fully extract xylitol over a significant amount of time, at high cost. and complexity. Likewise, much of the production of ethylene glycol and propylene glycol uses exclusively fossil hydrocarbon feedstocks such as oil or natural gas. Currently, non-fossil hydrocarbon feedstocks such as cellulosic biomass are not widely used industrially in glycol production. Such traditional production methods do not allow the invariant use of different raw materials and do not allow the recovery and conversion of conjugate hydrogenation products in the process line.

Unlike the prior art, the described methods in accordance with the present invention allow the use of various invariant unsorted or sorted incoming feedstock. For example, it is possible for the methods of the present invention to use a single ungraded feedstock consisting of wheat straw, hardwood and beets and, furthermore, it is also possible for the methods to use an alternating single graded feedstock based on either wheat straw, hardwood or beets, depending on supply availability, price fluctuations, etc. Using the feedstock-neutral processes described, dependence on exotic, expensive feedstocks with limited supply and uneconomical conversion is thus avoided, while further increasing efficiency by recovering and converting the associated hydrogenation products. Indeed, the embodiments described herein depart from the prior art with the goal of maximizing overall yield and significantly improving overall process equipment agility and operating efficiency. The methods of the present invention, for example, for the production of xylose and/or xylitol are aimed at maximizing yield and minimizing waste for a given weight of raw material, and in doing so, they can use multiple recovery cycles and operating cycles - with a constantly decreasing efficiency and yield per operation - to obtain products. Likewise, several processes aimed at producing glycols (from sugars, alditols, glycerol or the like) also focus on operations to maximize glycol yield while minimizing waste through the use of continuous cascading of continuously wasteful operating cycles. Numerous methods described herein employ approaches that do not follow the contrasting prior art with respect to separately maximizing xylitol yield or glycol yield. Rather, the described methods synergistically optimize overall yield by first recovering the original xylitol fraction while converting the remainder to glycol. Therefore, xylitol yield is reduced because some of the xylitol that could be recovered using prior art solutions is converted to glycol. Glycol yield is also reduced because some of the xylitol that could have been converted to glycol is recovered as xylitol. The yield of either xylitol or glycol appears to be suboptimal and is greatly hindered in the context of the prior art. However, unexpectedly and synergistically, embodiments of the described methods do contribute to increased overall combined yield of both xylitol and glycol (more than the separate and opposed production) thereby increasing plant productivity. As described herein, the methods are not limited to the production of xylitol and glycol.

Thus, there are therefore many product streams of interest - for example, xylitol and propylene glycol; sorbitol and ethylene glycol or a mixture of xylose/sorbitol and butanediols - can be extracted without the typical restrictions associated with the desire to maximize the yield of any individual component of the target product, which negatively impacts overall efficiency, cost and waste generation.

In one general embodiment, the method includes selecting at least two target products based on a raw material source such that the overall product yield for the at least two target products is such that the method is more efficient than if maximization were attempted release of only one product. The feed source may be a biomass feed, a hydrolyzate stream, a monomeric sugar stream, or a combination thereof, as discussed in more detail herein. In one embodiment, at least 90% of the feedstock is converted to the target alditols and glycols. In one embodiment, the raw material source is converted into at least two target products, wherein at least 10% of the total yield of the target product is one of the at least two target products, more specifically at least 15%, at least 20%, or at least 25% of the total yield of the target product. If it is necessary to maintain the overall yield of the target product, the method additionally includes modifying the selection of at least two target products if there is a change in the source of raw materials. The at least two target products may be a target [C5/C6] alditol, a target [C5/C6] alditol mixture, a target [C5/C6] monomer sugar, a target [C5/C6] monomer sugar mixture, a target a C2-C4 glycol, a target mixture of C2-C4 glycols, an organic acid, a compound in Table A herein, or a combination thereof, and wherein, specifically, at least one of the target products is a target C2-C4 glycol, or target mixture of C2-C4 glycols. Additionally, in this embodiment, a series of operating cycles or processes are carried out no more than two or three times with respect to any one feed stream, specifically no more than two times, and more particularly once. The operating cycle or process may be hydrogenation, hydrogenolysis, a biomass degradation process, or a separation process as discussed herein. The feed stream may be any feedstock or intermediate feed stream generated in the process. Exemplary feed streams include a biomass feed stream, a hydrolyzate stream, a monomeric sugar stream, an alditol stream, a glycol stream, or a combination thereof, as described herein. In a further embodiment, the feed stream may be modified or expanded with external material to change the composition of the feed stream.

More specifically, the embodiment described herein is directed to conditioning C5 sugars from streams containing C5 monomer sugars, which can be obtained from a variety of biomass sources, and converting such conditioned (purified) sugars into specific target alditols through hydrogenation and into specific target glycols via hydrogenolysis. The process can be directed toward producing target C5/C6 alditols and target C2-C4 glycols from biomass-derived mixed C5/C6 sugar streams while overcoming the efficiency and overall yield challenges experienced in the prior art. Alternatively, the process may be directed to conditioning a stream of C5 monomer sugars, provided that the C5 stream may contain 2-4 carbon sugars, 6-12 carbon sugars, glycerol, glycols, impurities or the like. Alternatively, the method aims to condition mixed C5 and C6 sugars at different C5/C6 ratios obtained from different biomass sources and isolate the target monomer sugar (e.g. xylose) or a mixture of target monomer sugars with the residual material converted to concrete target glycols via hydrogenolysis. Such described processes, including any of hydrogenation or hydrogenolysis, may be batch or continuous. In any number of embodiments, additional alditol may be provided to hydrogenolyze the residual mixed C5/C6 alditol stream to form a mixed C2-C4 glycol stream.

The formation of alditols and glycols as conjugate products is achieved through a combination of hydrogenation of hemicellulose hydrolysates based on C5/C6 monomers to alditols followed by hydrogenolysis of residual materials after crystallization/removal of the target alditols to produce glycols. Briefly, after hydrogenation of aldoses to alditols and target alditol(s), a variety of residual materials, including non-target alditols, can be converted to glycol products.

A suitable biomass feedstock should provide a mixture of monosaccharides that can, when hydrogenated, provide a range of alditols. Accordingly, but without limitation, various sources such as wheat straw, bagasse, sulfite liquor, hardwood, hybrid poplar, cereals, sugar cane, beet varieties, starch, etc., can be used as raw materials for the methods in accordance with the present invention described herein. After hydrolysis, the hydrolyzed solution provides a stream of monomeric sugars, the stream, for example, containing at least one C5 sugar, at least one C6 sugar, or combinations thereof (“mixed monomeric sugar stream”). The hydrolyzed mixed monomer sugar stream can be purified and then hydrogenated to produce a mixed alditol stream containing more than one alditol, such as any combination of xylitol, mannitol and sorbitol (“mixed alditol stream”). Target alditols such as xylitol and/or sorbitol can be recovered from solution using, for example, crystallization or chromatography. Such target alditols can be recovered to high purities suitable for food processing applications. Components of the hydrolyzed solution not recovered in the alditol recovery step (“residual mixed alditol stream”) can then undergo further hydrogenolysis to recover glycols for industrial purposes or food grade glycols. Optionally, additional alditols may be recovered after or before crystallization of the target alditols, if desired, rather than processed to produce glycol in accordance with the principle of "balanced total overall product recovery or stoichiometric recovery."

Components from the hydrolyzate stream obtained by decomposition and hydrolysis of the biomass feedstock can be characterized by chemical and/or physical determination. Definitions include: the percentage by dry weight of each component of the hydrolyzate stream, the ratio of C5 and C6 sugars in the hydrolyzate stream, the ratio of xylose and/or arabinose and total C5 sugars in the hydrolyzate stream. Based on this information, the estimated balance for recovery of the target materials in their respective forms is determined through a calculation to calculate the “optimal total overall product recovery or stoichiometric recovery rate.” A variety of target alditols and target glycols can be prepared using this method. A method for calculating the "optimal total overall product recovery or stoichiometric recovery" may be provided to calculate the yield of target alditol relative to the yield of target glycol. For example, in one embodiment, xylitol is extracted from the main stream after hydrogenation has been carried out with the hydrolyzate stream. After further processing, propylene glycol is purified from the stream. The ratio of xylitol yield to propylene glycol yield is measured and adjusted using parameters and conditions for process modification, biomass feedstock, addition of other C5/C6 sources, etc. to achieve optimized total overall product yield (compared to individual and opposing productions) or stoichiometric recovery. The same may be practiced with arabitol as the target alditol and ethylene glycol as the target glycol, or any combination of any alditol as the target alditol and any glycol as the target glycol, including combinations or mixtures of glycols as the target glycol and combinations or mixtures of alditols. For example, a mixture of xylitol and sorbitol can be obtained as the target alditol, and a mixture of propylene glycol and ethylene glycol can be obtained as the target glycol.

If xylitol is the target alditol, the choice of composition and structure of the biomass feedstock suitable for the described process may include a high ratio of xylose sugar derivatives to other sugar derivatives, as well as ease of availability for extraction of xylose sugar derivatives relative to other components.

The high ratio of xylitol to other alditols is illustrated by using xylitol at a concentration that is greater than or equal to 80% of the total alditol concentration. Thus, a solution concentrated to 80% w/w of all sugar-derived solids, with >80% of such solids being xylitol, would have a net concentration of >= 64% xylitol. Xylitol at a concentration that is greater than or equal to 90% of the total alditol concentration provides a net concentration of 72%, which provides additional higher yields. If xylitol is the target alditol, the total C6 sugar content of the raw material is specifically greater than 25%, specifically greater than 60%, and more specifically greater than 90%. In the same embodiment, the xylose content of the feedstock is specifically greater than 20%, more specifically greater than 50%, and even more specifically greater than 80%.

Suitable hydrogenation of aldoses, such as in a mixed stream of monomeric C5/C6 sugars, may further include process steps that promote the removal of ash, non-sugar organic compounds and other inorganic substances such as chloride and phosphate anions. Pre-treatment of biomass-based feedstocks may be used, and activated carbon may be used. Biomass feedstocks can be converted into a usable C5 monomer sugar stream by decomposition through a series of thermomechanical, alkaline, enzymatic or acid hydrogenation operations. The C5 monomer sugar stream may optionally contain 2-4 carbon sugars, 6-12 carbon sugars, glycerol, glycols, impurities or the like. An additional optionally “clean” C5 stream may be further provided by subjecting the C5 stream to any number of downstream operations, such as, by way of example, but without limitation, fractionation, lignin recovery, monosaccharide recovery, and organic/inorganic impurity removal operations, such as shown in Fig. 1. Therefore, among other advantages, the life of the catalyst can be extended, and impurities that interfere with the crystallization of alditols can be minimized.

To facilitate the crystallization of xylitol (as an illustrative target alditol product), it may be possible to include establishing and achieving threshold concentration levels of xylitol (minimum concentrations) and other alditols (maximum concentrations) to ensure extraction of xylitol in efficient yield and with suitable purity for applications requiring the highest quality . Additional information is described in the section “Aldite Extraction with Increased Efficiency” below.

Crystallization of the desired alditol product can also be facilitated by the optional use of an antisolvent (eg, ethanol or isopropanol) to increase the yield of alditol crystallization. Such an antisolvent may also provide ease of liquid/solid separation and improvement in filtration times.

In one embodiment, the method includes purifying a mixed stream of C5/C6 monomeric sugars obtained from a single biomass source to form a purified mixed stream of C5/C6 monomeric sugars to convert the purified mixed stream of C5/C6 monomeric sugars to C5/C6- alditols by hydrogenation; separating C5/C6 alditols into fractions separately or purifying C5/C6 alditols in whole or in part and forming a residual mixed stream of C5/C6 alditols (fewer amounts of target alditols). The residual mixed C5/C6 alditol stream (fewer target alditols) is converted into a hydrogenolysis feed stream for glycols. The target aldite products can be removed as crystals (solids) or liquid concentrates.

In one embodiment, the method includes purifying a mixed stream of monomeric C5/C6 sugars obtained from various biomass sources, and combining the purified mixture with monomeric C5/C6 sugars (e.g., substantially higher levels of C5), and adding such concentrated aldoses into available sources of monomeric C5/C6 sugars to enrich target C5 or C6 aldoses and to convert the purified mixed C5/C6 stream and/or complemented aldose sugar stream into C5/C6 alditols via hydrogenation; and separating the C5/C6 alditols into fractions separately or purifying the C5/C6 alditols in whole or in part. Also concentrated C5/C6 alditol streams can be selectively hydrogenated to mixed alditols with target alditols removed by crystallization, etc., and then to external alditols (such as glycerol) added to the residual mixed C5/C6 alditol stream before hydrogenolysis. As used herein, "glycerol" is the same as "glycerol".

In one embodiment, external C5 monomer enriched streams (from any source) can be added to a mixed C5/C6 monomer sugar stream derived from one or different biomass sources to complement the ratios of C5/C6 monomer sugars before hydrogenation and then extracted target aldite(s). Additional external non-target alditols (such as C3-glycerol or C6-sorbitol) can be added after hydrogenation and removal of the target alditol to complement subsequent conversion via hydrogenolysis to glycols.

The integrated process for producing target alditols and target glycols as conjugate products involves a unique combination of hydrogenation of hemicellulose hydrolysates to alditols (feed solution) followed by removal of target alditols from the feed solution followed by hydrogenolysis (residual materials from crystallization of target alditol) to produce glycols. Residual materials resulting from recovery of the target alditols include non-target alditols (eg, mixtures in varying proportions of arabitol, xylitol, sorbitol, mannitol, etc.).

In a particular embodiment, a concentrated solution of monomeric sugars is provided wherein the major component is xylose and 70% or more solids are present. If the total solids concentration of a given solution is increased to 75%-80% solids, a significant proportion of the xylose present can then be separated from the solution by fractional crystallization. The crystalline xylose thus obtained is separated from the original solution in a filter or centrifuge, and then dried and packaged in bags or drums. The xylose can then be converted to xylitol by dissolution in water, hydrogenation, for example using a Raney nickel catalyst, and further crystallization.

A variety of biomass-based feedstocks may be applicable to the described methods, including, by way of example, but without limitation, bagasse (e.g., sugarcane bagasse, sorghum cake, or sugar beet bagasse), corn cobs, corn cobs, corn kernel pericarp, corn straw, straw from cereals (for example, alfalfa, barley, oats, rice or wheat), cereals, hardwood (for example, birch, poplar, alder, eucalyptus, etc.), plant leaves, plant stems, softwood (e.g. cedar, hemlock, pine or spruce), sulfite lye, xylans from algal polysaccharides, or combinations thereof.

In one embodiment of this method, the biomass is not a genetically modified organism (GMO) or derived from genetically modified substances, that is, the biomass is non-GMO or “non-GMO.” In a specific embodiment, the feedstock to achieve a C5-fortified sugar content (eg, 60-80%) is non-GMO sugar cane bagasse, wheat straw, poplar, hybrid poplar, alder, or a combination thereof.

By way of example, and without limitation, the following industrially applicable formulations (individually and in combination) that can be recovered from mixed C5/C6 monomeric sugar streams using the various embodiments described herein are shown in Table A.

Hydrogenation

The monomeric C5/C6 sugar stream can be used directly as a hydrogenation feed stream, where the hydrogenation process converts the monomers to alditols resulting in a mixed C5/C6 alditol stream. Alternatively, the monomeric C5/C6 sugar stream may be concentrated to increase total solids prior to hydrogenation. Such concentration methods are described herein. Moreover, ethanol, methanol, isopropanol, n-propanol, etc. can be used in the hydrogenation process alone or in the form of mixtures based on co-solvent(s). The hydrogenation process may be a batch process, a continuous process, or combinations thereof.

Exemplary hydrogenation catalysts include those hydrogenation catalysts that are suitable for exposure to high pH (9 and above), high temperature and aqueous conditions. Such catalysts include transition metal catalysts such as nickel catalysts supported on zirconium, titanium or other heavy metal oxide supports; metallic nickel sponge catalyst; or similar ones. In one embodiment, the catalyst contains a combination of a zirconium compound and a polyacid/activator substance that forms a zirconyl activator precursor having a molar ratio of from 2:1 to 20:1; and wherein the polyacid/activator agent may be a polyacid containing an oxide or acid form of chromium, molybdenum, tungsten, or a combination thereof. In another embodiment, the catalyst contains nickel, an activator selected from bismuth, silver, tin, antimony, gold, lead, thallium, cerium, lanthanum, manganese or a combination thereof, and a support selected from zirconium dioxide or carbon. In one embodiment, the hydrogenation process is carried out using a nickel-based catalyst supported by zirconia, titanium dioxide, alumina, silica, chromium oxide, or a combination thereof.

In one embodiment, the catalyst comprises a support comprising a zirconium oxide activated by a polyacid or activator agent, the support being filled with a catalytically active metal such as Group 4 (Group IVA) metals, Group 10 (Group VIII) metals, Group 11 (Group 11) metals. group IB) or a combination thereof.

In one embodiment, the hydrogenation process comprises a continuous fluid jet downflow packed bed reactor containing a combined three phase of solid (hydrogenation catalyst), liquid (mixed stream of monomeric C5/C6 sugars with total solids content from about 20 to about 30% w/w, specifically with a total solids content of from about 22% to about 25% w/w) and gas (hydrogen). The process further utilizes a hydrogen pressure of from about 4137 to about 13790 kPa (about 600 to about 2000 psig); a temperature of from about 100 to about 160°C, specifically from about 140 to about 160°C; residence time from about 20 to about 40 minutes; and an initial pH value of from about 9 to about 12, specifically from about 10 to about 11, to achieve approximately 99% stoichiometric conversion of monomeric sugars to alditols.

In one embodiment, the hydrogenation process provides a feed stream containing from about 20% to about 25% monomer sugar on a dry weight basis, with the C5 sugars, xylose and arabinose, present at levels of about 80%, and the C6 sugar, glucose and fructose, present at levels of approximately 20%; hydrogen gas in a stoichiometric amount of a multiple of about 4 to about 6; an initial pH value of from about 8.0 to about 11.0, specifically from about 9.0 to about 10.0; a temperature of from about 120 to about 140°C; a hydrogen pressure of about 8274 to about 13790 kPa (about 1200 to about 2000 psig), specifically about 12411 kPa (about 1800 psig); and a liquid hourly space velocity (“LHSV”) of about 0.4 to 3.0, specifically about 1.0 to 1.5. In this embodiment, the hydrogenation catalyst may be a transition metal nickel catalyst (20-40% nickel) on a zirconium and/or titanium support matrix or a Raney nickel catalyst (20-60% nickel with copper activator) in dissolved aluminum matrix designed for a fixed bed reactor with liquid jet flow. In the Raney nickel embodiment, an alkaline hydroxide activator such as sodium hydroxide or potassium hydroxide may be used to maintain the pH in the range of 8.0 to 10.0.

The conversion of monomeric C5/C6 sugars to the corresponding C5/C6 alditols during hydrogenation is at least 95%, specifically at least 97%, and more specifically about 100%.

An optional two-step hydrogenation may be used if the stoichiometric conversion is less than 95%. For example, an optional continuous second stage reactor may be used as long as the first stage reactor achieves 90-95% conversion of monomeric sugars to alditols and the second stage reactor achieves 95-100% conversion to alditols. A two-stage reactor can operate at a higher LHSV - liquid hourly space velocity.

Known hydrogenation equipment and techniques can be used to carry out the hydrogenation process. In one embodiment, the equipment is a continuous fixed-bed trickle reactor having a column length:diameter ratio of approximately 10:2, specifically a once-through fixed-bed trickle reactor, where hydrogen and liquid feed the flow is supplied from above, and the liquid is supplied from below. The reactor can be installed to provide backflushing and on-site regeneration. The hydrogen pressure may be from about 4137 to about 13,790 kPa (about 600 to about 2,000 psig), specifically from about 12,411 kPa to 13,790 kPa (about 1,800 psig to 2,000 psig). sq. in.).

The hydrogenation feed or product feed may have a total solids content of from about 20 to about 27% w/w, specifically from about 22 to about 25% w/w. In addition, the pH of the hydrogenation feed stream may be from about 8.0 to about 11.0, specifically from about 9 to about 10. Sodium hydroxide may be the pH adjusting alkali used, but other alkalis may also be used, such as Potassium-calcium or lithium hydroxide/oxides.

When desired to achieve a desired feed concentration relative to the feed stream for the hydrogenation reaction, the mixed stream of C5/C6 monomeric sugars can be concentrated to increase the total solids content by removing water. In one embodiment, the mixed stream of C5/C6 monomeric sugars can be concentrated using a membrane to allow water to pass through, thereby increasing the concentration of the mixed stream of C5/C6 monomeric sugars composition. A suitable exemplary membrane may be a 40-5000 dalton membrane.

In one embodiment, the hydrogenation is carried out with a purified mixed C5/C6 sugars stream containing from about 20 to about 25% w/w total sugars in water, a pH of about 11, a liquid hourly space velocity (LHSV) of about 1 ,0, a hydrogen pressure of approximately 13,790 kPa (approximately 2,000 psig), a stoichiometric amount of hydrogen that is a multiple of about 3 to about 6, and a temperature of approximately 140°C, and is characterized by 99 % or more by converting monomeric C5/C6 sugars into alditols.

In yet another embodiment, the mixed C5/C6 alditol stream from the hydrogenation process comprises about 65% C5 alditol and about 35% C6 alditol. Additionally, the mixed C5/C6 alditol stream contains approximately 50% xylitol, 15% arabinite, 25% sorbitol and approximately 10% mannitol. In another embodiment, the mixed C5/C6 alditol stream contains at least 50% xylitol, 15% or less arabinite, 25% or less sorbitol, and 10% or less mannitol.

In one embodiment, when the hydrogenation process has shifted below 90% conversion of monomeric C5/C6 sugars to alditols, the process further includes a regeneration cycle in which the purified mixed feed stream of monomeric C5/C6 sugars is sent to an intermediate reactor with a partially deactivated nickel catalyst. substrate before direct hydrogenation to eliminate sulfur poisoning and fouling of the reactor, followed by stepwise washing of the catalyst with water, alkaline solution and ethanol to remove fouling agents, followed by drying with hydrogen and restoration of activation. Fouling includes one, more, or all of the following: saccharification (burning), scorching, charring and/or caramelization of sugars, sulfur poisoning, restriction of access to catalytic reaction sites by impurities or intermediates, and polymerization of sugars causing the catalyst to for hydrogenation it becomes physically damaged and clogged.

In one embodiment, the hydrogenation production is performed with a catalyst life in excess of only 4000 hours and a suitable run time of from about 1000 to about 1800 hours before staged catalyst regeneration occurs. Regeneration of the catalyst may take from about 16 to about 36 hours, or specifically 24 hours.

In one embodiment, the purified mixed C5/C6 monomer sugar stream contains C5/C6 monomer sugar, specifically about 25 to about 50% ethanol, and specifically about 25 to about 50% water. Ethanol and water, in combination with pH and temperature, increase the solubility of organic polymer impurities and, therefore, reduce equipment downtime.

In one embodiment, the given C5/C6 monomeric sugar feedstock may be supplemented prior to hydrogenation, for example by adding a more highly concentrated aldose stream. For example, xylose may be crystallized or concentrated separately from other C5/C6 streams and a concentrated C5 fraction added to a bulk fraction of monomeric C5/C6 sugars with offset levels of higher C5s such as xylose or arabinose. Consequently, the target aldoses can be concentrated to obtain the necessary mixtures for hydrogenation and subsequent subsequent recovery of alditols and glycols. In general, the higher the concentration of target aldite in the hydrogenation stream, the higher the yield of purified target aldite. If the concentration of target alditol in the hydrogenation stream is too low, for example below 25% w/w, then very little or no target alditol may be extracted. The concentration of target alditol in the hydrogenation stream can be increased, for example, by adding a high aldose feedstock, which is converted to target alditol during hydrogenation. The concentration of the target alditol may be greater than 25%, particularly greater than 60%, and more particularly greater than 90% in the hydrogenation stream.

Fig. 2 is an exemplary process flow diagram for the separation and crystallization step (40) including extraction (10) of the target aldite, extraction (11) of the enhanced efficiency aldite, extraction (12) of other alditols, and addition (13) of the missing alditol.

Extraction of target aldite

The hydrogenation product stream, which may be a mixed C5/C6 alditol stream, is processed to isolate the target alditols or mixtures of target alditols. The excretory products may be individual alditols (eg, sorbitol or xylitol) or mixtures of alditols (eg, mixtures with specific ratios of sorbitol, confectionery xylitol, or cough syrups). For example, extraction of xylitol can be carried out from an aqueous mixture of mixed alditols (xylitol, sorbitol and possible isomers alditol, arabitol and mannitol) by single-pass crystallization or stepwise crystallization by successive removal of water (for example, by evaporative concentration at elevated temperature) and subsequent reduction in temperature with induction of crystallization. The C5/C6 alditol extraction can be adapted to different feedstocks with different C5/C6 alditol ratios.

Water and co-solvents (eg, ethanol), if used, can be removed by methods including multiple evaporation, steam distillation, multiple evaporation using thermal compression flash evaporators, reverse osmosis, or a combination thereof.

In one embodiment, water removal is carried out at a temperature of from about 30 to about 120°C under vacuum, specifically from about 70 to about 110°C under reduced pressure, and more particularly from about 80 to about 100°C under reduced pressure, for example , being less than 30 kPa (200 mbar), specifically from about 10 to about 18 kPa (from about 100 to about 180 mbar) and, more specifically, from about 14 to about 17 kPa (from about 140 to about 165 mbar).

The concentrated feed stream may have a total dissolved solids content of from about 40% to about 90% w/w, specifically from about 60% to about 85% w/w, and more particularly from about 75% to about 85% w/w.

Aldite extraction with increased efficiency

Specific alditols, such as xylitol, arabitol, or sorbitol, or mixtures of alditols, can be isolated from an aqueous mixture of mixed alditols (such as xylitol, sorbitol, arabitol, and mannitol) using generally recognized as completely harmless (GRAS) solvent precipitation or crystallization, industrial chromatography, including pseudo-moving bed (SMB), or combinations thereof, specifically GRAS solvent deposition or crystallization, to isolate the target aldite or mixture of target aldites. Crystalline forms of the target alditol can be selected in accordance with the description, while liquid compositions based on mixtures of the target alditol can also be prepared in accordance with the description.

Suitable solvents include lower alcohols (eg ethanol, isopropanol, etc.) and mixtures thereof with water. An exemplary GRAS solvent includes ethanol.

Before crystallization or precipitation, the alditol solution (eg xylitol) may be treated with activated carbon to remove impurities that may interfere with alditol crystallization. Suitable activated carbon includes powdered activated carbon, granular activated carbon and the like. or a combination thereof. Other methods for removing crystallization inhibitors include one or more of the following, optionally in combination with activated carbon treatment: ion exchange, membrane filtration, solvent extraction. Other conditioning steps include stepwise electrodialysis, strong acid and ion exchange resin treatment, and chemical precipitation with calcium sulfate, and optionally further include recovery of waste inorganic material. Determination of whether and to what extent conditioning of the alditol solution or mixed C5/C6 alditol stream prior to crystallization is necessary can be determined by one skilled in the art without undue experimentation. For example, analytical techniques known in the art can be used to determine the type and amount of components in an alditol solution or a mixed stream of C5/C6 alditols so that appropriate purification technique(s) can be used.

The crystallization process can be carried out using a continuous or batch process. Crystallization equipment and techniques known in the art may be used to effect crystallization of the target aldite. Suitable crystallization equipment and liquid/solid separation equipment include crystallizers (horizontal crystallizers, vertical crystallizers, cooling crystallizers, evaporative crystallizers), centrifuges, and the like.

Once the desired weight of solids is achieved during the crystallization process, the solids in the target aldite can be isolated using known techniques in the art, such as filtration, centrifugation, combinations thereof, and the like. The solids may be washed, dried, sorted, or a combination of these steps.

The feed solution from the crystallization process can be further processed to provide additional yield of target aldite or other aldite, or used as a feedstock (“residual mixed C5/C6 alditol stream”) to produce glycols via hydrogenolysis.

In one embodiment, crystallization of a concentrated aqueous effluent containing predominantly xylitol (e.g., >75% total alditol) and low levels of other alditols, such as galactitol, lixitol, and sorbitol, can be accomplished by cooling the concentrated aqueous effluent containing total dissolved solids from about 50 to about 85% w/w, specifically from about 65 to about 85% w/w, and more particularly from about 70 to about 85% w/w, from about 60 to about 100° C. to temperature from about -10 to about 40°C, particularly from about 20 to about 35°C, optionally adding a target aldite seed crystal.

An antisolvent, such as ethanol, isopropanol, or other GRAS solvent, may optionally be added to the concentrated aqueous feed stream while maintaining a temperature that is below the flash point of the antisolvent, for example, below about 40°C, specifically below about 35°C for ethanol. Optionally, a seed crystal of the desired aldite can be added, optionally inducing and/or promoting crystallization.

The concentrated aqueous feed stream may be cooled to a target temperature that is below room temperature, which is specifically about -10°C to about 20°C and more specifically about -5°C to about 5°C. Once the target aldite has crystallized, a slurry of about 15 to about 45% solids, specifically about 20 to about 40% solids, can be fed to a solids recovery device such as a centrifuge to separate the solids from the feed solution. Using this exemplary process, high purity (>98%) of aldite can be achieved, and cooling can be adjusted to the desired yield depending on the purity of the solid product.

In one embodiment, crystallizing xylitol as the target alditol in pure form from mixed alditol streams may involve establishing and achieving threshold concentration levels of xylitol (minimum concentrations) and other alditols (maximum concentrations) to ensure recovery of xylitol in efficient yield and at suitable purity for the application. applications requiring the highest quality. Threshold levels depend on the water:antisolvent ratio present in the system.

The concentration of a component in the crystallization solution is calculated as % total solids multiplied by the proportional concentration of aldite in the total solids.

The following factors may influence the concentration threshold;

- solubility limit of the component in the solvent at the applied temperature;

- influence of the antisolvent (and its concentration);

- influence on the solubility of components of other dissolved substances, which can either suppress or increase their solubility;

- the tendency of another component to interfere with the crystallization of the desired crystalline component - for example, by embedding the required component into the crystal lattice.

Examples of threshold limits have been defined in the following ranges, that is, the maximum levels of each alditol in the crystallization solution that will still provide effective purification of xylitol when xylitol is the target alditol:

- in general, the presence of high concentrations of sorbitol and mannitol provides a significant influence on the physical nature of xylitol crystallization. Thus, high levels of sorbitol and mannitol result in co-crystallization of sorbitol and/or mannitol with xylitol, which may slow down the filtration rate of the resulting mixture.

With respect to xylitol, to produce xylitol, a xylitol concentration of at least 20% w/w, more specifically more than about 42% w/w based on the weight of all solids, more specifically more than 60% w/w in solution is required to achieve better yield; (e.g. 80% total solids in solution with a minimum xylitol content of 80% w/w of total solids). Additionally, in this embodiment, for xylitol, the concentration of arabinite was less than 10% w/w of the total solids content, otherwise the purification of xylitol is deteriorated. Also in this embodiment, for xylitol, mannitol has a low level of solubility, resulting in a threshold level being set at a concentration of 10% w/w. At levels greater than 10% w/w mannitol, based on total solids, undesirable cocrystallization of mannitol with xylitol occurs. In one embodiment, it has been found that a mannitol content of 4% w/w or less in the crystallization solution provides successful purification of xylitol. Additionally, in this embodiment, for xylitol, when sorbitol is present at concentrations that are greater than or equal to 15% w/w of total solids, the crystallization rate and filtration rates are reduced.

In this embodiment, with respect to the xylitol threshold, xylitol is a minimum of 60% of the total solids, more specifically greater than 80% of the total solids and, after evaporative concentration, to a minimum of 75% w/w of the total solids in solution at from about 60 to about 70°C, with the actual xylitol concentration specifically being greater than 60%. If an antisolvent is used in this embodiment, the actual xylitol concentration is greater than 50%. The maximum threshold levels of other components depend on the water:antisolvent ratio present in the system. Arabitol is present at less than 10% volume in a 50:50 water:ethanol system because higher concentrations of this alditol have a negative effect on the kinetics and purity of xylitol crystallization. Mannitol is present in less than 4% volume due to cocrystallization with xylitol. The exact threshold levels may vary slightly based on the overall composition of the solution and the amount of antisolvent.

The crystallization solution for xylitol may have a total dissolved solids content high enough to control xylitol crystallization, but low enough to avoid rapid bulk crystallization. In several embodiments, the crystallization solution may have a total dissolved solids content of from about 40% to about 80% w/w, specifically from about 60% to about 85% w/w, and more particularly from about 70% to about 75% w/w /weight.

In one embodiment, for xylitol crystallization, the xylitol content as a % of total solids in the crystallization solution is 50% or more, specifically 55% or more, more particularly 60% or more. Additionally, in this embodiment, the amount of arabitol as a % of the total solids in the crystallization solution is less than or equal to 10%, specifically less than or equal to 5%, and more specifically less than or equal to 2%. Alternatively, in this embodiment, the amount of mannitol as a % of total solids in the crystallization solution is less than or equal to 10%, specifically less than or equal to 5%, and more specifically less than or equal to 2%. Alternatively, in this embodiment, the amount of arabitol as a % of the total solids in the crystallization solution is less than or equal to 10%, specifically less than or equal to 5%, and more specifically less than or equal to 2%; and the amount of mannitol as a % of the total solids in the crystallization solution is less than or equal to 10%, specifically less than or equal to 5%, and more specifically less than or equal to 2%. In this embodiment, the solution does not include an antisolvent. In another embodiment, the solution may contain a combination of water and an antisolvent such as ethanol, specifically from a ratio of about 95:5 water:ethanol to a ratio of 5:95 water:ethanol, more specifically from a ratio of about 95:5 water:ethanol to a ratio of 5: 95 water : ethanol.

In one embodiment, for xylitol crystallization, the xylitol content as a % of total solids in the crystallization solution is 50% or more, specifically 55% or more, more particularly 60% or more; and the amount of sorbitol as a % of the total solids in the crystallization solution is less than or equal to 15%, specifically less than or equal to 10%, and more specifically less than or equal to 5%. In this embodiment, the solution does not include an antisolvent. In another embodiment, the solution may contain a combination of water and ethanol, specifically from a ratio of approximately 95:5 water:ethanol to a ratio of 0:1 water:ethanol.

In an alternative embodiment, chromatography can be used to separate the alditols, thereby eliminating the need to regulate threshold levels during the alditol crystallization step.

In one embodiment, the mixed C5/C6 alditol stream is at least partially separated by chromatography into a C5 alditol fraction and a C6 alditol fraction.

In one embodiment, the mixed C5/C6 alditol stream is separated by chromatography into a C5 alditol fraction and a C6 alditol fraction, and the target alditol is crystallized from the C5 alditol fraction using ethanol and water. The feed liquid containing residual alditols can be sent to the hydrogenolysis process for conversion to glycols.

In one embodiment, recovering the desired alditol from the mixed C5/C6 alditol stream by crystallization involves removing ethanol, water, or a combination thereof from the mixed C5/C6 alditol stream.

In one embodiment, the target alditol is a C5 alditol or a C6 alditol.

In one embodiment, the target alditol is xylitol. In one embodiment, the target alditol is sorbitol or arabitol.

In one embodiment, the xylitol resulting from the crystallization process contains from about 90 to about 100% xylitol, specifically from about 96 to about 99.99% xylitol, and more specifically from about 98.5 to about 99.99% xylitol . In one embodiment, the xylitol obtained from the crystallization process contains less than 1% other alditols.

Extraction of other aldites

After extracting the desired alditol or mixture of alditols from the alditol stream, the remaining mixed aqueous alditol feed stream containing a fraction of the desired alditol, such as xylitol, can be processed into fractions of sorbitol, arabitol, mannitol, or a combination thereof, by industrial chromatography. The target alditol products at this stage can be in either liquid or crystalline form. Optionally, the desired alditol, typically about 85% to about 95% pure, can be concentrated and crystallized during a second extraction.

Adding the missing amount of aldites

Once most of the target alditols (eg, xylitol or sorbitol) have been extracted from the alditol stream, the remaining C5/C6 alditol can be discarded to produce the remaining alditols for hydrogenolysis and hence a particular range of glycol products. For example, higher C6s will promote the formation of propylene glycol and butanediol isomers as hydrogenolysis products, while C5 alditols will promote the formation of ethylene glycol and glycerol as hydrogenolysis products.

Using methods such as chromatography, precipitation, etc., it is possible to obtain separate fractions enriched in C5-alditol and C6-alditol. Carrying out hydrogenolysis with enriched fractions will lead to the target glycol products.

Fig. 3 is a process flow diagram for the hydrogenolysis and separation step (50), including hydrogenolysis (14) and glycol separation processes (15).

Hydrogenolysis

Residual alditols and mixtures of alditols can be converted by hydrogenolysis to the desired hydrogenolysis products including glycols and glycerol. Hydrogenolysis can be carried out at high temperature and pressure in the presence of hydrogen.

Exemplary target glycols to be formed include: ethylene glycol, propylene glycol, 1-3-propanediol, butanol, butanediol isomers (1,2 butanediol; 1,4-butanediol; 1,3-butanediol and 2,3 butanediol), as well as mixtures. Glycerol may be another target hydrogenolysis product.

Exemplary hydrogenolysis catalysts include transition metal, noble metal, and metal matrix catalysts formulated for aqueous conditions and high pH (above 9). The exemplary catalyst described above for the hydrogenation process can be used in the hydrogenolysis process. In one embodiment, the hydrogenolysis catalyst is a nickel-based catalyst (20-40% nickel) supported on a zirconia or titanium dioxide matrix.

In one embodiment, hydrogenolysis is carried out at a temperature of approximately 240°C; a pressure of about 6895 to about 13790 kPa (about 1000 to about 2000 psig); a pH of approximately 10 or greater; and liquid hourly space velocity (LHSV) from about 0.5 to about 3.0.

In one embodiment, the hydrogenolysis is carried out at a temperature of from about 210 to about 250°C, specifically from about 220 to about 240°C; a pressure of about 6895 to about 13790 kPa (about 1000 to about 2000 psig), specifically from about 8274 to about 12411 kPa (about 1200 to about 1800 psig); a pH of from about 9.0 to about 11.0, specifically about 10.0; and a liquid hourly space velocity (LHSV) of about 0.5 to about 2.0, particularly about 0.8 to about 1.5, and more particularly about 1.0. Additionally, this embodiment uses a feed stream based on about 20 to about 25% mixed alditols (eg, C5/C6 alditols) in water, on a dry weight basis. The amount of hydrogen may be a stoichiometric multiple of about 4 to about 6. Additionally, an activator such as sodium hydroxide is used in this embodiment. The conversion of C5/C6 alditol to mixed glycols can be greater than 70%, specifically greater than 80%.

In one embodiment, the method includes continuously performing hydrogenolysis of a residual mixed C5/C6 alditol stream having a total solids content of about 20 to about 25 wt/wt% alditol in water, at a pH of about 11, LHSV of about 1.0, pressure hydrogen at approximately 13,790 kPa (approximately 2,000 psig) and a temperature of approximately 240° C. in the presence of a nickel-based catalyst to form a mixed stream of glycols containing propylene glycol, ethylene glycol, glycerin, butanediol isomers, or a combination thereof.

In one embodiment, the hydrogenolysis process produces a mixed glycol stream containing propylene glycol (about 15% to about 25%), ethylene glycol (about 20% to about 30%), glycerol (about 10% to about 30%), and butanediol isomers (from about 10% to about 20%).

The hydrogenolysis feed stream and the resulting mixed glycol stream from the hydrogenolysis process may contain ethanol and water. In this case, ethanol can be added as a co-solvent, increasing the solubility of hydrogen and reducing energy costs. Alcohols have a lower heat of vaporization, and the use of an ethanol/water azeotrope with a low boiling point can further reduce energy costs.

In one embodiment, the residual mixed C5/C6 alditol stream used as a hydrogenolysis feed stream to carry out the hydrogenolysis process may contain alditol, about 25 to about 50% ethanol, and about 25 to about 50% water.

In one embodiment, the hydrogenolysis process is carried out using a nickel-based catalyst supported by zirconium oxide, titanium dioxide, or a combination thereof.

In one embodiment, when the hydrogenolysis process is shifted below 90% conversion of C5/C6 alditols to glycols, the method further includes a regeneration cycle comprising stepwise washing of the catalyst with hot water, caustic solution and ethanol to remove fouling agents, followed by drying using hydrogen and restoration of activation.

Glycol separation processes

The product stream from the hydrogenolysis process, containing a mixture of glycols and glycerol, can be separated into the desired hydrogenolysis products, including the desired glycol products. Exemplary separation processes include a combination of classical distillation, extraction methods, and extractive and/or azeotropic distillation to isolate and purify glycols with similar boiling points. Target hydrogenolysis products include ethylene glycol, propylene glycol, glycerol, and butanediol isomers.

Propylene glycol can be separated into industrial grade and United States Pharmacopoeia (USP) grade propylene glycol through azeotropic distillation. Through azeotropic distillation, ethylene glycol can be separated into industrial grade ethylene glycol and grade ethylene glycol to produce polyethylene terephthalate (“PET”) resin. Butanediols can be concentrated and purified to obtain individual 1,2-; 2,3- and 1,3-butanediols, respectively, for industrial applications. Glycerol can be extracted and/or reused in mixed alditol hydroprocessing feedstocks before hydrogenolysis and conversion to propylene glycol and ethylene glycol.

In one embodiment, a method for producing C5/C6 alditols and C2-C4 glycols from biomass-derived mixed C5/C6 sugar streams includes causing the biomass source to decompose and hydrolyze under alkaline, acidic, enzymatic, or acidic and enzymatic conditions to form a stream a biomass hydrolyzate containing one or more of a sugar monomer, oligomeric sugar, hemicellulose, cellulose, solubilized lignin, and impurities such as non-sugar organic compounds, ash, and inorganic contaminants; conditioning the biomass hydrolyzate stream to remove lignin, non-sugar organic compounds and inorganic contaminants to form a purified mixed C5/C6 sugar stream; carrying out acid hydrolysis of the purified mixed stream of C5/C6 sugars to form a mixed stream of monomeric C5/C6 sugars; hydrogenation of a mixed stream of monomeric C5/C6 sugars to form a mixed stream of C5/C6 alditols; separating the target aldite from the mixed C5/C6 aldite stream by crystallization, discarding the residual mixed C5/C6 aldite stream; hydrogenolysis of the residual mixed stream of C5/C6 alditols with the formation of a mixed stream of glycols and isolation of the target glycol. In this embodiment, ensuring the decomposition and carrying out hydrolysis of the biomass source is carried out in an alkaline environment. In this embodiment, the biomass is obtained from wheat straw. In this embodiment, conditioning is carried out using selective progressive membranes and activated carbon treatment. In this embodiment, the hydrogenation is carried out under nickel catalysis in a fixed bed; and wherein hydrogenolysis is carried out using a nickel catalyst. In one embodiment, the target alditol is xylitol and the target glycol is propylene glycol. The inorganic contaminants removed are chlorides, sulfates, phosphates, or a combination thereof.

Xylitol, sorbitol, other alditols, and certain alditol mixtures (e.g., with certain ratios of sorbitol, xylitol) produced by the methods described can be used in a wide range of applications, including use as a sweetener in food and health care products oral cavity, as a component in pharmaceutical preparations and for industrial applications. As a sweetener, they can be used alone or in combination with other sweeteners in confectionery, chewing gum, sauces, beverages and the like. Because xylitol is non-cariogenic and does not affect insulin levels in people with diabetes, it has particular uses in foods. In addition, due to its very high negative heat of solution, the use of xylitol is accompanied by a cooling sensation in the consumer's mouth. Due to this effect, xylitol is commonly used in chewing gum to provide a feeling of freshness. In pharmaceutical preparations, it can be used as a sweetener, excipient, etc. Oral care products may include toothpaste, tooth powder, mouthwash, breath films, and the like.

Alditols also find use in a variety of industrial applications, including the preparation of resins and surfactants, use as a plasticizer for a number of polymers, and the like.

Target glycols produced using the described methods include propylene glycol for wide industrial applications as well as for the cosmetic food industries; ethylene glycol, intended to produce quality grade resins for the production of polyethylene terephthalate (PET) containers, and butanediol isomers for pharmaceutical precursors and resins with additional positive characteristics.

Pulps from biomass decomposition processes can be used to produce fibreboard, fine paper and/or other pulp applications to replace traditional hardwood and softwood pulps.

The isolated lignin fractions can be used for specific industrial applications, including the production of lignosulfonates, the production of resins, etc., or for use as low-sulfur fuels.

In one embodiment, the method includes causing the decomposition of poplar wood, bagasse, or a combination thereof using acidic conditions to produce a mixed stream of C5/C6 sugars; selecting a target aldite or a target mixture of aldites; conditioning the mixed stream of C5/C6 sugars to remove lignin, organic impurities and inorganic impurities; hydrolysis of a mixed stream of C5/C6 sugars to form a mixed stream of monomeric C5/C6 sugars; continuous hydrogenation of a mixed stream of monomeric C5/C6 sugars to form a mixed stream of C5/C6 alditols; separating the target aldite or target alditol mixture from the mixed C5/C6 alditol stream, discarding the residual mixed C5/C6 alditol stream; continuous hydrogenolysis of the residual mixed stream of C5/C6 alditols to form a mixed stream of C2-C4 glycols; and isolating the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product is either the target alditol/target alditol mixture or the target glycol/target glycol mixture; wherein the target alditol is xylitol and the target glycol is propylene glycol or a combination thereof; and wherein the xylitol is isolated by crystallization, optionally using an antisolvent of ethanol or isopropanol.

In another embodiment, the method comprises continuously hydrogenating a mixed stream of C5/C6 monomeric sugars to form a mixed stream of C5/C6 alditols; separating xylitol from the mixed C5/C6 alditol stream and discarding the residual mixed C5/C6 alditol stream; continuous hydrogenolysis of the residual mixed stream of C5/C6 alditols to form a mixed stream of C2-C4 glycols; and isolating the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product consists of either xylitol or the target glycol or the target mixture of glycols.

In one embodiment, the method includes isolating a target monomeric C5/C6 sugar or a target mixture of monomeric C5/C6 sugars from a mixed stream of monomeric C5/C6 sugars to form a residual mixed stream of monomeric C5/C6 sugars; continuous hydrogenolysis of the residual mixed stream of monomeric C5/C6 sugars to form a mixed stream of C2-C4 glycols; and isolating the target glycol or target mixture of glycols from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product is either the target monomeric C5/C6 sugar/target mixture of monomeric C5/C6 sugars or the target glycol/target mixture of glycols. In this embodiment, the target monomeric C5/C6 sugar may be xylose.

In another embodiment, the method includes selecting at least two target products based on a biomass-based feedstock source; converting the biomass feedstock into at least two target products, wherein at least 10% of the total yield of the target product is one of the at least two target products; and, if necessary, maintaining the overall yield of the target product, modifying the selection of at least two target products if there is a change in the source of biomass-based raw materials; wherein one of the at least two target products is a target C2-C4 glycol or a target mixture of C2-C4 glycols; and wherein the remainder of the at least two target products is a target [C5/C6]-alditol, a target [C5/C6]-alditol mixture, a target [C5/C6]-monomeric sugar, a target [C5/C6]- mixture monomeric sugars or a combination thereof; and wherein the processing is carried out no more than two or three times with respect to any one feed stream, where the processing is hydrogenation, hydrogenolysis, a biomass decomposition process or a separation process; and the feed stream is a biomass feed stream, a hydrolyzate stream, a monomeric sugar stream, an alditol stream, a glycol stream, or a combination thereof. In this embodiment, at least one step in the method can be carried out in a continuous manner. Additionally, in this embodiment, the method can be carried out in a single production facility or on a single production line.

In one embodiment, the method includes selecting at least two target products based on the source of the hydrolyzate stream; converting the hydrolyzate stream into at least two target products, wherein at least 10% of the total yield of the target product is one of the at least two target products; and, if necessary, maintaining the overall yield of the target product, modifying the selection of at least two target products if there is a change in the hydrolyzate flow; wherein one of the at least two target products is a target C2-C4 glycol or a target mixture of C2-C4 glycols; and wherein the remainder of the at least two target products is a target [C5/C6]-alditol, a target [C5/C6]-alditol mixture, a target [C5/C6]-monomeric sugar, a target [C5/C6]- mixture monomeric sugars or a combination thereof; and wherein the processing is carried out no more than two or three times with respect to any one feed stream, where the processing is a hydrogenation, hydrogenolysis or isolation process; and the feed stream is a hydrolyzate stream, a monomer sugar stream, an alditol stream, a glycol stream, or a combination thereof. In this embodiment, at least one step in the method can be carried out in a continuous manner. Additionally, in this embodiment, the method can be carried out in a single production facility or on a single production line.

In another embodiment, the method includes selecting at least two target products from a source of a mixed stream of monomeric sugars; converting the mixed stream of monomeric sugars into at least two target products, wherein at least 10% of the total yield of the target product is one of the at least two target products; and, if necessary, maintaining the overall yield of the target product, modifying the selection of at least two target products if there is a change in the mixed flow of monomeric sugars; wherein one of the at least two target products is a target C2-C4 glycol or a target mixture of C2-C4 glycols; and wherein the remainder of the at least two target products is a target [C5/C6]-alditol, a target [C5/C6]-alditol mixture, a target [C5/C6]-monomeric sugar, a target [C5/C6]- mixture monomeric sugars or a combination thereof; and wherein the processing is carried out no more than two or three times with respect to any one feed stream, where the processing is a hydrogenation, hydrogenolysis or isolation process; and the feed stream is a monomer sugar stream, an alditol stream, a glycol stream, or a combination thereof. In this embodiment, at least one step in the method can be carried out in a continuous manner. Additionally, in this embodiment, the method can be carried out in a single production facility or on a single production line.

The features and advantages will be more fully illustrated by the following examples, which are provided for purposes of illustration and should not be construed as limiting the invention in any way.

EXAMPLES Example 1.

Cellulose and small fractions of suspended lignin do not dissolve in the alkaline pulp solution, and high molecular weight hemicellulose can be extracted with cellulose to increase pulp yield. Process conditions for pulping can result in a reduction in the molecular weight of hemicellulose, which contributes to a higher degree of extraction of hemicellulose from solution and, consequently, a higher yield of C5/C6 sugars. Wheat straw hemicellulose has a typical xylan:glucan ratio of approximately 75:25. Therefore, if all cellulose (C6) is removed, the highest yield of C5 sugars (xylose/arabinose) overall may be 75% xylose/arabinose from the hemicellulose fraction. If all the wheat straw cellulose was converted to C6 sugars, and in this case the wheat straw hemicellulose was converted to C5 and C6 sugars, then the C6 sugars were at most 2.19 times more C5 sugars. If all the sugars (from cellulose and hemicellulose) were converted to monomers, then C5 could account for a maximum of about 31% of the total sugars from cellulose and hemicellulose. If all C6 celluloses are removed, the maximum concentration of C5 sugars from the hemicellulose fraction can only be 75%. Thus, it is possible to target specific C5-C6 sugars and ratios and create appropriate conditions for fiber pulp as well as other pre-treatments to promote a) specific sugars and hydroprocessing sugars and b) regulation of C5 levels through fiber recovery masses of C6 (cellulose).

Example 2. Hydrogenation of C5/C6 sugars

Xylose and arabinose (C5 sugars) and related raw materials based on hexose C6 sugars (glucose, galactose, mannose and fructose) are hydrogenated at a concentration of dry mass of sugar in water of 20-25%, at pH 10-12, at 125-150° C and at 12411-13790 kPa (1800-2000 psig) with a range of proprietary catalysts. The liquid hourly space velocity (LHSV) is 0.4-1.5 in a stoichiometric excess of hydrogen of 4-6. The overall conversion is 99% of sugars to alditols. By-products include unreacted aldoses and possibly, alternatively, isomers of C5 or C6 alditols. Tables 2-A, 2-B and 2-C show a series of hydrogenations under various conditions and catalysts illustrating the conditions for the preparation of alditols.

When C5- and C6-alditols are produced together with target alditols, fractionation and purification to materials for industrial purposes and/or food use are carried out, and other alditols not related to the target alditol are sent for hydrogenolysis to produce glycols. Partial recovery of target alditols, such as xylitol or sorbitol, without requiring high throughput procedures for high recovery-separation rates (for example, more than 75-90% for xylitol or sorbitol), significantly reduces the total costs of alditol separation processes and at the same time provides optimization of the overall yield of alditols and glycols. Thus, the coproduction of alditols and glycols results in lower overall costs and higher yields. Tables 2-B and 2-C illustrate the basics of xylose production hydrogenation and conversion of xylose to xylitol using a sponge metal catalyst containing about 50 to about 80% nickel.

Briefly, when preparing alditols there are two main products of interest (as discussed above, for example, sorbitol and xylitol). The main purpose of producing mixed alditols (with or without the target alditols removed) is to obtain C5/C6 feedstock for hydrogenolysis. Thus, mixed alditols after hydrogenation can provide a source for specific alditols (such as mannitol or arabitol) or alditols for hydrogenolysis to produce high-value glycols.

Example 3: Selective concentration of C5-alditols by elementary operations

When hydrogenating C5/C6 sugars, C5/C6 sugars will generally, regardless of the C5/C6 ratio or isomer variability of the various C5/C6 alditols, result in a 97-99% conversion of sugar aldoses to the corresponding alditols. Alditol rejection may change the isomeric compositions slightly, but the overall conversion should be constant and high.

If, for example, xylitol is the target alditol, then several process parameters may be possible for concentrating the xylitol and subsequent further purification to a liquid or crystallized product. Initially, in the case of lower concentrations of xylitol, for example less than 30% xylitol of all C5/C6 alditols, classical and/or newly developed industrial chromatography, which includes pseudo-moving bed (SMB) technology, can be used. Depending on the system configuration, resin types, elution line and recirculation line, the concentration can shift from 30% to 50% to 70%. Currently, other prior art methods focus chromatographic separation entirely on ensuring maximum recovery of the target material and concentrating the materials. This dual criterion of high removal rates and high purity of recovered fractions is challenging from an operational and cost perspective. More equipment is needed, higher recirculation rates, higher dilution rates, etc. Thus, 20-40% recovered at a higher purity is considered acceptable. The goal is to purify and concentrate a fraction of the target alditols, but without the need for complete extraction. The subsequent production of glycols after hydrogenolysis provides a final conjugated product with additional positive characteristics for the target alditols. Additionally, by converting the physical state from non-volatile alditols, which are difficult to separate, to volatile glycols, which can be easily separated by distillation, the overall total cost of separating alditols and glycols is lower. Likewise, sorbitol or mannitol (C6-alditol) may be targeted as the main alditol product.

Table 3 lists several alternative resins and configurations of SMB systems, as well as the resulting concentrations of xylitol and sorbitol from the corresponding alditol mixtures.

Example 4. Concentration and crystallization of alditols

Alditols (xylitol, arabinite, sorbitol, mannitol and other epimeric alditols) are characterized by a maximum solids concentration in water after hydrogenation of 25%. This mixture may be further concentrated by pseudo-moving bed chromatography using resins selected to retain the C6 alditols and concentrate the C5 in the permeate and/or produce alditol at 25%, and by reverse osmosis or other water removal techniques and/or by selective converting, for example, arabinite to xylitol. Higher concentrations of alditols with higher percentages of xylitol can be crystallized with or without the addition of antisolvents (such as ethanol) to facilitate crystallization.

Individual alditols have varying degrees of solubility in water, with sorbitol and arabitol having the highest solubility values, followed by xylitol and then mannitol at a given temperature. Additional solubility is due to antisolvents such as ethanol/water mixtures used to increase the solubility of alditols. The higher the ethanol concentration, the lower the solubility of aldite. The combination of solubility differences and the possible use of ethanol in the extraction and crystallization steps allows for controlled product recovery.

Table 4-A shows the effect of xylitol concentration on xylitol crystallization. Table 4-B shows the effect of ethanol/water solvent volume on xylitol crystallization.

The combination of producing a number of specific C5/C6 alditols (xylitol or sorbitol) from the corresponding mixed raw materials based on C5/C6 aldoses (xylitol, arabitol, mannitol, galactitol, sorbitol) involves the combined stepwise application of water solubility depending on the water/ethanol ratio for the combination aldoses, for example, using chromatography to concentrate xylitol or other alditols to suitable levels to extract a high purity fraction. This purer fraction can in turn be recrystallized to produce a series with higher purities (eg greater than 98%).

Briefly, the target alditols can be removed with a portion of the non-target alditols used for hydrogenolysis.

Example 5. Hydrogenolysis of alditols to produce glycols

Table 5-A illustrates the typical conversion of mixed alditols to glycols via hydrogenolysis. Note in the table that, for example, C5-xylitol produces more ethylene glycol (EG) (26%) than the corresponding C6-sorbitol input for EG (13%). Considering that "green EG" used for renewable sustainable PET bottles is preferred in the market over traditional non-green EG, the transformability of the method developed herein is illustrated. The focus on propylene glycol (PG) may shift to a higher C6/C5 ratio. The resulting glycols PG, EG, GLY (glycerol) and BD (butanediol isomers) can be separated using classical distillation and/or extractive and azeotropic distillation.

Example 6. Effect of sorbitol and mannitol on xylitol purification

Model mixtures of crystallization solution systems containing varying amounts of xylitol, mannitol, sorbitol and other sugars were prepared by dissolving mixtures of alditols and aldoses in water at 85°C to obtain a solution with a total solids content of % w/w as given in Table 6 Each solution was then added to the crystallization vessel at 5°C. The temperature of the contents of the vessel was controlled. At 30°C, a xylitol seed crystal (3 g) was added along with 100 ml ethanol (95%). Solid xylitol was removed by filtration 1 hour after the addition of the seed crystal. The data in Table 6 demonstrates the effect of sorbitol and mannitol concentrations on xylitol purification in model systems.

Mannitol is characterized by a low level of solubility. As shown by the data in Table 6, at mannitol concentrations >10%, undesirable cocrystallization of mannitol with xylitol occurs. When the mannitol content was 4% w/w or less in the crystallization solution, successful purification of xylitol was achieved.

The data from Table 6 also shows that sorbitol concentrations >15% cause a decrease in xylitol crystallization rates, and at the same time, filtration rates also decrease.

While the invention has been described with reference to an exemplary embodiment, those skilled in the art will appreciate that various changes may be made and elements may be replaced by their equivalents without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its essential scope. Thus, it is intended that the present invention is not limited to the particular embodiment described as the best contemplated embodiment of this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (16)

1. A method for obtaining at least two target products - target alditols and target glycols as conjugated products, including: providing a mixed stream of monomeric sugars C5 and C6 obtained from decomposed raw materials based on plant biomass; continuous hydrogenation of a mixed stream of C5 and C6 monomer sugars to form a mixed stream of C5 and C6 alditols; separating the first target product - the target aldite or the target mixture of aldites, from the mixed stream of C5 and C6 aldites with discarding the residual mixed stream of C5 and C6 aldites; continuous hydrogenolysis of the residual mixed stream of C5 and C6 alditols to form a mixed stream of C2-C4 glycols; And isolating the second target product - the target glycol or the target mixture of glycols, from the mixed stream of C2-C4 glycols; wherein at least 10% of the total yield of the target product is either target alditol/target alditol mixture or target glycol/target glycol mixture, and the first target product is isolated by crystallization. 2. The method of claim 1, wherein the mixed stream of C5 and C6 monomer sugars is enriched with C5 monomer sugar, optionally by adding a source of C5 monomer to the mixed stream of C5 and C6 monomer sugars. 3. The method of claim 1, wherein the mixed stream of C5 and C6 monomer sugars is enriched with C6 monomer sugar, optionally by adding a source of C6 monomer to the mixed stream of C5 and C6 monomer sugars. 4. The method according to claim 1, characterized in that the first target product is the target alditol, namely xylitol or sorbitol. 5. The method according to claim 4, characterized in that xylitol is isolated by crystallization, optionally using ethanol or isopropanol as an antisolvent. 6. The method according to claim 1, characterized in that the first target product is a target mixture of alditols, including xylitol, sorbitol or a combination thereof. 7. The method according to claim 1, characterized in that the mixed stream of C2-C4 glycols contains propylene glycol, ethylene glycol, glycerol, butanediol isomers or a combination thereof. 8. The method according to claim 1, characterized in that the target glycol is propylene glycol. 9. The method according to claim 1, characterized in that the target glycol is ethylene glycol.

Images