Patent Grant
11111513
The present disclosure is related to removing one or more hydrolysis byproducts from lignocellulosic hydrolysate liquor. More particularly, the present disclosure is related to using gas stripping to remove one or more hydrolysis byproducts from a lignocellulosic hydrolysate.
Hydrolysis of lignocellulosic material can produce one or more byproducts. One or more of such byproducts can inhibit enzymatic activity of enzymes, growth of yeast and other microorganisms, and/or fermentation of monosaccharides to a biochemical. For example, acid hydrolysis of corn stover can produce one or more compounds that can inhibit enzymatic activity of cellulases and/or hemicellulases, growth of yeast and other microorganisms, and fermentation of monosaccharides to a biochemical such as ethanol. Examples of such compounds include acetic acid from ester hydrolysis of acetyl groups on xylan and lignin, phenolic compounds derived from lignin hydrolysis, and/or furfural and 5-hydroxymethylfurfural (HMF), which can be produced by the dehydration of pentoses and hexoses, respectively.
There is a continuing need to provide methods and systems to remove fermentation inhibitors such as furfural.
In some embodiments of the present disclosure is a method of removing at least a portion of furfural from a hydrolysate composition, wherein the method includes:
In some embodiments of the present disclosure is a system for removing at least a portion of furfural from a whole broth hydrolysate composition. The system includes:
In some embodiments of the present disclosure is a method of removing at least a portion of furfural from a hydrolysate composition, wherein the method includes:
In some embodiments of the present disclosure is a system for removing at least a portion of furfural from a hydrolysate composition, wherein the system includes:
Disclosed in embodiments herein are methods and systems for removing at least a portion of fermentation inhibitor such as furfural from a hydrolysate composition such as a whole broth hydrolysate composition.
As used herein, a “hydrolysate” is derived from at least partial hydrolysis of polysaccharide in a biomass material into oligosaccharides and/or monosaccharides. For example, a polysaccharide such as cellulose can be hydrolyzed into six carbon sugars such as glucose and a polysaccharide such as hemicellulose can be hydrolyzed into five carbon sugars such as xylose.
Biomass includes, for example, lignocellulosic material such as corn cobs and corn stover (e.g., stalks and leaves) made available during or after harvesting of the corn kernels, fiber from the corn kernel, switchgrass, farm or agricultural residue, wood chips or other wood waste, and other plant matter (grown for processing into bioproducts or for other purposes). Lignocellulosic biomass includes hemicellulose, cellulose, and lignin.
A hydrolysate can be a “whole broth” hydrolysate or a fraction thereof. As used herein a whole broth hydrolysate composition refers to a product of biomass hydrolysis and includes a solid component and a liquid component. In some embodiments, the solid component can include solid, unhydrolyzed materials of a biomass feedstock such as lignin, cellulose, and/or hemicellulose. In some embodiments, the liquid component can be a liquid hydrolysate (or liquor) and can include water, sugar and byproducts of hydrolysis such as fermentation inhibitors. Examples of fermentation inhibitors include furfural, hydroxymethylfurfural (I-IMF), phenol compounds, mixtures thereof, and the like. In some embodiments, a whole broth hydrolysate includes at least pentose, furfural, cellulose and/or hexose, and lignin. A whole broth hydrolysate can have a total solids (dissolved and suspended solids) content in the range from 10 to 30 percent, from 12 to 25 percent, or even from 13 to 20 percent.
A hydrolysate composition can be made by hydrolyzing a lignocellulosic substrate to provide a solid component including glucan and lignin and a liquid component including a monosaccharide such as xylose and/or glucose.
Hydrolysis of polysaccharides in biomass can occur by a wide variety of techniques such as contacting the biomass with hot water, acid, base, enzyme(s), and the like.
Hydrolyzing lignocellulosic substrates to provide, e.g., xylose and/or glucose is described in, e.g., U.S. Pat. No. 5,424,417 (Torget et al.); U.S. Pat. No. 6,022,419 (Torget et al.); and U.S. Pat. No. 8,450,094 (Narendranath et al.), and U.S. Publication Number 2010/0233771 (McDonald et al.), wherein the entireties of said patent documents are incorporated herein by reference for all purposes.
Hydrolysis can create byproducts that can be inhibitory to downstream processes such as enzymatic saccharification of polysaccharide and/or oligosaccharide material and/or downstream fermentation of monosaccharides. Examples of such inhibitory byproducts from hydrolysis include acetic acid from ester hydrolysis of acetyl groups on xylan and lignin; phenolic compounds derived from lignin hydrolysis; and/or furfural and 5-hydroxymethylfurfural (HMF), which can be produced by the dehydration of pentoses and hexoses, respectively.
Hydrolysis of a lignocellulosic biomass is described herein below with reference to
Before hydrolysis, a lignocellulosic feedstock can be prepared by a variety of techniques such as size reduction, steaming, combinations of these, and the like. As shown in
B.1 Acid Hydrolysis
As shown in
During acid hydrolysis, the “severity” can be adjusted by varying one or more of time period, temperature, and pH of hydrolysis. In some embodiments, during hydrolysis an aqueous composition can have a pH in the range from 1 to 5, or even 2 to 3. The aqueous composition can include an acid such as sulfuric acid present in a concentration in the range from 0.2 to 1.3% w/w, or even 0.5 to 1% w/w. In some embodiments, acid hydrolysis can be performed for a time period in a range from 15 minutes to 5 hours, or even 30 minutes to 4 hours. In some embodiments, acid hydrolysis can be performed at a temperature in the range from greater than 100° C. to 170° C., or even from 110° C. to 150° C.
Acid hydrolysis can be performed in a variety of system and apparatus configurations. In some embodiments, an acid hydrolysis system can include a first reactor system in fluid communication with a source of lignocellulosic biomass and a source of an aqueous composition. The first reactor system can include at least one reactor configured to contact the lignocellulosic biomass with the aqueous composition to hydrolyze at least a portion of the hemicellulose into one or more oligosaccharides and/or one or more pentoses, and form a first, whole broth hydrolysate composition including at least pentose, cellulose, lignin, and furfural.
B.2 Optional Steam Explosion
Optionally, as shown in
During steam explosion, cellulose (either in a whole broth hydrolysate or hydrolysate with a portion of xylose liquor removed) can be subjected to a relatively elevated pressure and temperature so that moisture impregnated within the cellulose network is in a liquid state. Then, the pressure can be reduced so that the liquid “flashes” to a gas state so that the sudden expansion with the cellulose network causes at least a portion of the cellulose structure to rupture, thereby increasing the surface area of the cellulose for increased exposure to cellulase enzymes. In some embodiments, the superheated hydrolysate composition can be flashed to a reduced pressure by continuously discharging the composition through an orifice. In some embodiments, a hydrolysate composition including cellulose can be subjected to a temperature in the range from 320° F. to 400° F. and a pressure in the range from 75 psig to 235 psig, followed by suddenly exposing the hydrolysate composition to a reducing pressure such as atmospheric pressure. In some embodiments, a hydrolysate composition including cellulose can be subjected to a temperature in the range from 350° F. to 385° F. and a pressure in the range from 120 psig to 195 psig, followed by suddenly exposing the hydrolysate composition to a reducing pressure such as atmospheric pressure.
After steam explosion 295, a fermentation inhibitor such as furfural can be stripped from the steam-exploded hydrolysate using a furfural stripping device 292 to inject a gas 293 into the hydrolysate and recover a gas 294 that includes at least a portion of the stripped furfural. Gas stripping of furfural is further discussed in section D below.
Alternatively, as shown in
In the embodiment shown in
B.3 Enzymatic Hydrolysis
As shown in
In some embodiments, as shown in
A liquefaction system 480 can include one or more vessels (not shown) containing a whole broth hydrolysate and configured to maintain the whole broth hydrolysate at a pH and temperature for a time period to convert at least a portion of the cellulose in the lignocellulosic biomass into an oligosaccharide and/or a monosaccharide. In some embodiments, the temperature of the whole broth hydrolysate during at least a portion of liquefaction is in a range from 45° C. to 65° C., or even from 50° C. to 60° C. In some embodiments, the pH of the whole broth hydrolysate during at least a portion of liquefaction is in a range from 4 to 6, or even from 4.5 to 5.5. In some embodiments, the liquefaction time period is in the range from 2 to 20 hours, or even from 6 to 8 hours.
As shown, a saccharification system 485 is in fluid communication with the liquefaction system 480. In some embodiments, a saccharification system can include at least one reactor configured to receive the liquefied cellulose so as to saccharify at least a portion of the liquefied cellulose and form glucose. A saccharification system 485 can include one or more batch reactors (not shown) in fluid communication with the liquefaction system 225 to receive the liquefied cellulose. The saccharification system 485 can be configured to maintain a whole broth hydrolysate at a pH and a temperature for a time period to convert at least a portion of the cellulose in the lignocellulosic biomass into an oligosaccharide and/or a monosaccharide. In some embodiments, the temperature of the whole broth hydrolysate can be in a range from 45° C. to 65° C., or even from 50° C. to 60° C. In some embodiments, the pH of the whole broth hydrolysate can be in a range from 4 to 6, or even from 4.5 to 5.5. In some embodiments, the saccharification time period is in the range from 48 to 120 hours, or even from 112 to 114 hours.
A hydrolysate composition can be used to propagate a microorganism. Propagation can be used to reproduce an initial (e.g., “starter”) population of a microorganism so as to generate a larger population of the microorganism that is sufficient for use in fermentation and to make a fermentation product. For example, a first cell mass of a microorganism, a carbon source, and a nutrient source can be combined in a propagation system so that the first cell mass can reproduce and form a second cell mass (e.g., 10, 20, 50, 100, 150, or even 200 times or more greater than the first cell mass). The second cell mass can then be used in a fermentation system to convert one or more monosaccharides (e.g., from a pretreated lignocellulosic biomass) into a fermentation product that includes a biochemical such as bio-protein, bio-oil, or a biofuel (e.g., ethanol, butanol, and the like). Propagation is further described in U.S. Pat. No. 9,340,767 (Narendranath); U.S. Pat. No. 9,034,631 (Narendranath et al.); U.S. Pat. No. 8,450,094 (Narendranath et al.); and U.S. Pat. No. 9,234,167 (Narendranath et al.); U.S. Pat. No. 9,416,376 (Narendranath et al.); U.S. Pub. No. 2015-0368679-A1 (Narendranath et al.); and WO 2016/205596 (Narendranath et al.), the entirety of which patent documents are incorporated herein by reference for all purposes.
Microorganisms that can convert one or more monosaccharides into a biochemical include, e.g., algae, bacteria and/or fungi such as yeast. The product biochemicals can vary depending on the conditions that are provided. In many embodiments, the biochemicals include biofuels such as ethanol, butanol, and the like. In some embodiments, the microorganism includes one or more ethanologenic microorganisms referred to as “ethanologens”. As used herein, an “ethanologen” refers to a microorganism that can convert one or more monosaccharides (e.g., glucose and the like) into at least ethanol.
Exemplary yeast and fungus include the genus of, Aspergillus, Candida, Pichia, (Hansenula), Phanerochaete, Kloeckera (Hanseniaspora), Kluyveromyces, Rhodotorula, Torulopsis, Zygosaccharomyces, Yarrowia, and Saccharomyces. In some embodiments, the yeast is a strain of Saccharomyces cerevisiae yeast. In some embodiments, the microorganism to be propagated includes genetically modified yeast such as genetically modified Saccharomyces cerevisiae that can convert glucose and xylose into a biochemical such as ethanol.
As used herein, a “carbon source” refers to one or more compounds that include at least one carbon atom and can be used by a microorganism such as yeast to grow and/or reproduce to create additional biomass. Exemplary carbon sources include monosaccharides such as glucose, fructose, galactose, mannose, xylose and the like; disaccharides such as lactose, maltose, sucrose, cellobiose and the like; oligosaccharides; polysaccharides such as cellulose, hemicelluloses, starch, xylan and the like; single carbon substrates including only one carbon atom such as methanol; and polyols such as glycerol, but not limited thereto. In some embodiments, a whole broth hydrolysate can be used as a carbon source.
In addition to a carbon source, a nutrient source is also included to help propagate microorganisms such as ethanologens. As used herein, a “nutrient source” refers to one or more materials that can be used by a microorganism to grow and/or reproduce to create additional microorganisms and is different from a carbon source. The nutrient source used can include a stillage component (e.g. whole stillage, thin stillage and/or syrup). Whole stillage is well-known and is a byproduct of distilling a fermentation product. For example, a well known process for making whole stillage is a corn grain-to-ethanol process.
As shown in
Embodiments of the present disclosure include using a gas to remove (strip) at least a portion (e.g., substantially all) of one or more fermentation inhibitors from a hydrolysate (e.g., whole broth hydrolysate). A gas can be injected into a hydrolysate composition at one or more points in a process from acid hydrolysis through enzymatic hydrolysis, and before fermentation.
Using a gas to strip a fermentation inhibitor is described herein below with reference to
D.1 Inject Gas
Gas stripping can include injecting a first volume of a gas into a hydrolysate (e.g., a whole broth hydrolysate composition) to provide a treated, hydrolysate composition. The hydrolysate composition includes furfural in a first concentration and the treated, hydrolysate composition includes furfural in a second concentration. By injecting a gas into the hydrolysate composition to treat it, at least a portion of the furfural transfers into the gas from the hydrolysate composition such that the second concentration of furfural in the treated, hydrolysate composition is less than the first concentration of furfural in the untreated hydrolysate. In some embodiments, the first concentration of furfural in the hydrolysate is 500 ppm or greater, 750 ppm or greater, 1000 ppm or greater, 1200 ppm or greater, 1500 ppm or greater, or even 3000 ppm or greater. In some embodiments, the second concentration of furfural in a treated, hydrolysate composition is less than 500 ppm, less than 250 ppm, less than 100 ppm, less than 50 ppm, or even less than 1 ppm (e.g., undetectable).
A variety of types of gases can be used to strip an inhibitor such as furfural. In some embodiments, a gas can include air, oxygen, inert gas, and mixtures thereof.
The temperature and pressure of the gas/hydrolysate interface can be selected so as to facilitate transfer of a fermentation inhibitor such as furfural into the gas phase. For example, the vapor pressure of the fermentation inhibitor(s) such as furfural can be considered when determining the temperature and pressure of the hydrolysate during gas stripping. In some embodiments, it is desirable to select a temperature and pressure of the given unit operation such as acid hydrolysis, enzymatic hydrolysis, and the like. In some embodiments, a temperature can be selected specifically for gas stripping that may be different from a target temperature that is selected for a different process such as hydrolysis and/or propagation. For example, gas stripping can be performed at a temperature in the range from 20° C. to 100° C., or even 70° C. to 95° C. In some embodiments, gas stripping can be performed under vacuum, at atmospheric pressure, or a pressurized environment.
Another factor to consider can include devices or elements to facilitate mixing of a hydrolysate composition and an injected gas. See, e.g.,
A volume of gas to treat a hydrolysate composition can be selected depending on, e.g., the volume of the hydrolysate to be treated. In some embodiments, the volume of the gas is injected at a rate of at least 0.01 volume unit of gas per volume unit of hydrolysate composition per minute, at least 0.05 volume unit of gas per volume unit of hydrolysate composition per minute, at least 0.1 volume unit of gas per volume unit of hydrolysate composition per minute, at least 0.5 volume unit of gas per volume unit of hydrolysate composition per minute, at least 1.0 volume unit of gas per volume unit of hydrolysate composition per minute, or even at least 5.0 volume unit of gas per volume unit of hydrolysate composition per minute. An example of “volume unit of gas per volume unit of hydrolysate composition per minute” is “liter of gas per liter of hydrolysate composition per minute.”
A variety of systems and devices can be used to inject a gas into a hydrolysate composition. For example, a gas such as compressed air can be sparged into a vessel via one or more gas ports. The gas ports may positioned along one or more linear gas supply tubes or pipes positioned near the bottom of a vessel. As another example, gas ports may be positioned around a ring-shaped tube or pipe positioned near the bottom of a vessel. In some embodiments, the gas ports can be coupled to an existing vessel such as an acid hydrolysis tank, a liquefaction tank, a saccharification tank, and/or a propagation tank. For example, as shown in
Another way to determine and control the desired level of mixing is to set the rpms of the mixing apparatus. In some embodiments, the stirring mechanism can operate an rpm in the range from 300 rpms to 3000 rpms, or even 500 to 1500 rpms.
As another example, a dedicated device or tank can be used to strip a fermentation inhibitor such as furfural from a hydrolysate composition such as a whole broth hydrolysate.
D.2 Recovering Gas
Referring to
Referring to
A gas recovery system can be in fluid communication with one or more vessels such as tank 507 and column 601. The gas recovery system can be configured to recover gas from the stripping process. Such a system can include hoods, ducts, pipes, and the like.
A gas stripping process as described herein can be implemented at one or more points in a process such as process 100 for making ethanol via fermentation. Several points are illustrated in
As shown in
As shown in
As shown in
As shown in
With respect to
As shown in
In some embodiments, the whole broth hydrolysate can be heated in a dedicated gas stripping device as described herein (e.g., device 154) and/or in an existing vessel dedicated to another primary purpose (e.g., yeast propagation system 159) to an elevated temperature that facilitates the faster removal of a fermentation inhibitor such as furfural.
In some embodiments, a mixer such as stirring mechanism 506 may be used to facilitate the mass transfer of a fermentation inhibitor from the whole broth hydrolysate into the stripping gas.
An exemplary embodiment is described where yeast propagation system 159 includes a tank similar to tank 507. Tank 507 can be at least partially filled with whole broth hydrolysate from enzymatic hydrolysis 135. Optionally, the whole broth hydrolysate present in tank 507 can be heated to a temperature in the range from 20° C. to 100° C. Gas can be injected as described herein for a time period to strip furfural from the whole broth hydrolysate. In this embodiment, the stripping process may be operated in batch mode (e.g., 1-5 hours) until the furfural concentration has been reduced to an acceptable level. After gas stripping, the temperature of the tank 507 contents can be lowered if desired for fermentation. One or more additional propagation components can be combined with the treated whole broth hydrolysate so as to perform yeast propagation. For example, while using the whole broth hydrolysate as a carbon source, a nutrient source (e.g., thin stillage from corn ethanol production) and yeast source can be added to the treated whole broth stillage. The balance of the tank 507 volume can be filled with water.
It can be particularly advantageous to remove at least a portion (e.g., substantially all) of the furfural and/or other fermentation inhibitors from the material used to generate the desired yeast cell mass in order to provide good yeast growth that will facilitate subsequent fermentation. By having good yeast growth in yeast propagation, desirable fermentation performance can be realized in the subsequent whole broth fermentation step even in the presence of moderate levels of furfural in fermentation.
The recovered gas streams described herein that include furfural can be treated as described in section D.3.
D.3 Treating Gas to Remove Fermentation Inhibitor
The gas streams recovered from gas stripping operations described herein include fermentation inhibitors such as furfural. Such gas streams can be treated to recover furfural as a byproduct for subsequent use or sale, or can be treated to remove at least a portion of the furfural from the gas stream and dispose of it. In some embodiments, treating a recovered gas stream to remove the furfural include gas scrubbing, distillation, and the like. For example, a recovered gas stream can be cooled to condense and recover at least a portion of one or more of furfural and moisture as liquids. After condensing, the gas stream may still contain some furfural, albeit in a relatively small amount. The gas stream can be recycled and used to strip additional furfural from a hydrolysate composition. In some embodiments, the recovered gas can include air such that the recovered gas can be used as combustion air (e.g., in a boiler system) so that the furfural is degraded to a product of combustion.
As shown in
This experiment simulated a dedicated furfural stripping device such as device 140 in
This experiment simulated stripping furfural during enzymatic saccharification in a sachharification reactor such as 485 in
This experiment simulated stripping furfural from a yeast propagation tank similar to the tank 507 in
The present application claims the benefit of commonly owned provisional Application having Ser. No. 62/339,600, filed on May 20, 2016, which provisional Application is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2017/033241 | 5/18/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/201233 | 11/23/2017 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 8450094 | Narendranath et al. | May 2013 | B1 |
| 9034631 | Narendranath et al. | May 2015 | B2 |
| 9068206 | Kwiatkowski et al. | Jun 2015 | B1 |
| 9278379 | Carlson et al. | Mar 2016 | B2 |
| 9340767 | Narendranath | May 2016 | B2 |
| 9469859 | Bly et al. | Oct 2016 | B1 |
| 10113187 | Bushong et al. | Oct 2018 | B2 |
| 20090098617 | Burke et al. | Apr 2009 | A1 |
| 20140024826 | Narendranath et al. | Jan 2014 | A1 |
| 20150203885 | Noordam | Jul 2015 | A1 |
| 20150368679 | Narendranath et al. | Dec 2015 | A1 |
| 20180171285 | Narendranath et al. | Jun 2018 | A1 |
| 20180273988 | Lewis et al. | Sep 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| 101942529 | Jan 2011 | CN |
| 2009046538 | Apr 2009 | WO |
| 2011070602 | Jun 2011 | WO |
| 2012103281 | Aug 2012 | WO |
| 2012125739 | Sep 2012 | WO |
| 2014072390 | May 2014 | WO |
| 2014072393 | May 2014 | WO |
| 2014072395 | May 2014 | WO |
| 2014176531 | Oct 2014 | WO |
| 2015075277 | May 2015 | WO |
| 2015165951 | Nov 2015 | WO |
| 2015165952 | Nov 2015 | WO |
| WO-2015165951 | Nov 2015 | WO |
| 2016096971 | Jun 2016 | WO |
| 2016201031 | Dec 2016 | WO |
| 2017091361 | Jun 2017 | WO |
| 2017218380 | Dec 2017 | WO |
| 2018185071 | Oct 2018 | WO |
| Entry |
|---|
| Hu et al., Scientific Reports, vol. 5, No. 9428, pp. 1-9; Mar. 30, 2015 (of record). (Year: 2015). |
| Hu et al., Scientific Reports, vol. 5, No. 9428, pp. 1-9; electronically available Mar. 30, 2015 (of record). (Year: 2015). |
| International Search Report for International Application No. PCT/US2017/033241, dated Aug. 16, 2017 (3 pages). |
| Buijtenen et al., “Furfural Production by ‘Acidic Steam Stripping’ of Lignocellulose”, ChemSusChem, pp. 2132-2136, 2013, (6 pages). |
| Hu et al., “A Novel Method for Furfural Recovery Via Gas Stripping Assisted Vapor Permeation by a Polydimethylsiloxane Membrane”, Scientific Reports, pp. 1-9, Mar. 30, 2013, (9 pages). |
| Anish et al., “Bioethanol from Lignocellulosic Biomass”, Part III Hydrolysis and Fermentation, pp. 159-173, (8 pages). |
| Canilha et al., “Bioconversion of Sugarcane Biomass into Ethanol: An Overview about Composition, Pretreatment Methods, Detoxification of Hydrolysates, Enzymatic Saccharification, and Ethanol Fermentation”, Journal of Biomedicine and Biotechnology, vol. 2012, Article ID 989572, (15 pages). |
| Number | Date | Country | |
|---|---|---|---|
| 20190292573 A1 | Sep 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62339600 | May 2016 | US |
