Patent Application
20150119607
1. Technical Field
The invention relates to methods and systems directed to renewable materials and biofuels production. Aspects of the invention relate to separating lignocellulosic feedstock into various fractions for improved processing.
2. Discussion of Related Art
Lignocellulosic biomass contains sugars in multiple forms, such as soluble sugars, starches, hemicelluloses, and cellulose. Some sugars, such as soluble sugars, are relatively accessible for utilization. Other sugars, such as cellulose and hemicellulose, require multiple processing steps to prepare them for fermentation. Moreover, the ease of access depends on the plant tissue in which the sugars are found, with the soft inner pith easier to digest and the hard outer rind requiring harsher conditions to break down.
Processing of lignocellulosic biomass is challenging because the accessibility and processing conditions vary among the different forms of sugars. In some lignocellulosic processing schemes, harsh conditions are used to break down even the least accessible biomass sugars, and providing these harsh conditions throughout the process for all of the sugars requires increased capital and operating expenses. Also, processing carried out under harsh conditions requires that the soluble sugars present in the biomass be removed before further processing in order to avoid their degradation. The need to remove soluble sugars during the process further increases capital expenses.
Additionally, lignocellulosic feedstocks contain substantial quantities of water. The cost, power demand, and performance efficiency of certain equipment is variably impacted by hydraulic load. For instance, industrial boilers are sensitive to the moisture content of the combusted material. Altering the moisture content of the lignocellulosic feedstock, such as by preferentially converting fractions containing lower moisture content, could allow for preferential disposition of feedstock fractions with varying moisture content.
There is a need and desire for more economical processes and systems for processing lignocellulosic biomass, particularly in the production of renewable materials such as biofuels.
The invention is directed to methods and systems for producing biofuels and other renewable materials, as well as biofuel component compositions made according to such methods. Compared to other schemes for processing of lignocellulosic biomass, the methods and systems described below may result in minimized capital, reduced operating expenses, and increased yield.
According to some embodiments, a method of producing a renewable material may be achieved by separating lignocellulosic feedstock into two or more fractions, such as three, four, five, or even more fractions. For example, the various fractions may include rind, pith, leaves, juice, wax cut, and/or trash. As another example, one or more of the various fractions may be enriched in cellulose, hemicellulose, and/or lignin.
The lignocellulosic feedstock used herein may include cellulose, hemicellulose, and/or lignin. For example, the lignocellulosic feedstock may include energycane, sugarcane, miscanthus, napier grass, elephant grass, sweet sorghum, arundo, switchgrass, hybrids thereof and/or combinations thereof. As another example, the lignocellulosic feedstock may include grasses, legumes, forbs, hardwoods, softwoods, municipal solid waste, paper mill residue, forest litter, fruit waste, citrus waste, and/or agricultural residues.
In certain embodiments, an automated separation device may be used to separate the lignocellulosic feedstock.
In certain embodiments, the method also includes pretreating at least one of the fractions, and further treating the pretreated fraction or fractions to produce a renewable material. According to some embodiments, each of the fractions may be pretreated. Each of the fractions may be pretreated separately, or one or more of the fractions may be pretreated simultaneously with at least one other fraction.
In certain embodiments, juice may be extracted from the lignocellulosic feedstock prior to separating the lignocellulosic feedstock. Alternatively, juice may be extracted from the lignocellulosic feedstock subsequent to separating the lignocellulosic feedstock. In other embodiments, juice may not be substantially extracted from the separated lignocellulosic feedstock fraction prior to pretreatment. A juice fraction that is extracted may be sent to a sucrose production train within a biorefinery.
Since the fractions may vary in terms of ease with which they may be broken down into sugars, various levels of harshness may be used in the pretreatment process. For example, a fraction comprising rind may be pretreated using a harsh or relatively more harsh pretreatment process. Conversely, a fraction comprising pith and/or leaves may be pretreated using a mild or relatively more mild pretreatment process. More particularly, a pith fraction may be pretreated by hydrolyzing the pith fraction with low or no acid at a temperature of at least 110° C., then the pith fraction may be hydrolyzed with an enzyme cocktail to produce sugars for fermentation. Similarly, a trash fraction may be pretreated by hydrolyzing the trash fraction with low or no acid at a temperature of at least 110° C., then the trash fraction may be hydrolyzed with an enzyme cocktail to produce sugars for fermentation.
According to some embodiments, the pretreatment may use an ionic liquid, an acid, a base, an enzyme, and/or water. For example, an acid used in the pretreatment may include an inorganic acid, an organic acid, a mineral acid, a Bronsted acid, and/or a Lewis acid. More specifically, an acid used in the pretreatment may include sulfuric acid, hydrochloric acid, sulfonic acid, phosphoric acid, nitric acid, acetic acid, lactic acid, formic acid, and/or oxalic acid. As another example, a base used in the pretreatment may include an inorganic base, an organic base, a mineral base, a Bronsted base, and/or a Lewis base. More specifically, a base used in the pretreatment may include ammonia, ammonium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, lime, calcium hydroxide, and/or calcium oxide. As yet another example, enzymes used in the pretreatment may include cellulases, glucanases, endoglucanases, exoglucanases, cellobiohydrolases, glucosidases, hemicellulases, esterases, acetylxylanesterases, pectinases, and/or the like. As a further example, facilitating proteins, such as expansins and/or swolleins, may be used in the pretreatment. Additionally, at least in some embodiments, pretreatment may be carried out on one or more of the fractions without heating. Additionally, at least one of the fractions may be burned to generate steam and/or electricity.
After separating the lignocellulosic feedstock into fractions, the fractions may be directed to various areas within a biorefinery. For example, a rind fraction may be sent to cane handling equipment for sugar recovery. A bagasse remainder may be sent to a boiler for power production, while sugar from the rind may either be sent to a sucrose recovery unit or to a fermentation unit. As another example, wax from a wax cut fraction may be sent to a wax recovery unit. Any fiber remainder may be burned.
According to some embodiments, at least one of the fractions may be converted to one or more sugars, such as sucrose, glucose, fructose, mannose, galactose, xylose, arabinose, various hexoses, various pentoses, cellobiose, and/or oligosaccharides. The sugar(s) may be converted into a renewable material. Examples of such renewable materials include ethanol, n-butanol, isobutanol, 2-butanol, fatty alcohols, isobutene, isoprenoids, triglycerides, lipids, fatty acids, lactic acid, acetic acid, propanediol, and/or butanediol. The renewable material may include material suitable for use as biofuels, blendstocks, chemicals, intermediates, solvents, adhesives, polymers, and/or lubricants. The renewable material may include one or more biofuel components, such as lipids, or an alcohol, namely ethanol, butanol, and/or isobutanol.
In certain embodiments, at least one of the fractions is converted to one or more sugars, and the sugar or sugars are converted into a renewable material suitable for use as a biofuel. The biofuel may include biofuel intermediates, gasoline, biogasoline, biogasoline blendstocks, diesel, biodiesel, green diesel, renewable diesel, biodiesel blend stocks, jet fuel, and/or kerosene. In some embodiments, at least one of the fractions is combusted.
According to some embodiments, a method of producing a biofuel component may be achieved by separating lignocellulosic feedstock into two or more fractions, pretreating at least one of the fractions, and further treating the at least one pretreated fraction to produce a biofuel component.
According to some embodiments, a lignocellulosic feedstock separated into a plurality of fractions may include between about 30% and about 85% of a first fraction that includes primarily rind by dry weight, and between about 15% and about 70% of a second fraction that includes primarily pith by dry weight. In certain embodiments, the first fraction may include between about 30% and about 50% cellulose by dry weight, and/or between about 15% and about 30% hemicellulose by dry weight, and/or between about 15% and about 25% lignin by dry weight. In certain embodiments, the second fraction may include between about 15% and about 40% cellulose by dry weight, and/or between about 9% and about 25% hemicellulose by dry weight, and/or between about 5% and about 19% lignin by dry weight.
According to some embodiments, a lignocellulosic feedstock separated into a plurality of fractions may include a first fraction enriched in polysaccharides, and a second fraction enriched in lignin.
According to some embodiments, a biofuel component composition may be derived from a lignocellulosic feedstock that was separated into a plurality of fractions, with between about 30% and about 85% of a first fraction that includes primarily rind by dry weight, and between about 15% and about 70% of a second fraction that includes primarily pith by dry weight, prior to converting one or more of the fractions into a biofuel component. The biofuel component may include an alcohol, such as ethanol and/or butanol.
According to some embodiments, a biorefinery for producing biofuels may include a tissue separation unit for separating tissues of a lignocellulosic feedstock, a pretreatment unit for treating at least some of the separated tissues of the lignocellulosic feedstock, and a conversion unit for producing a renewable material from the separated tissues. In certain embodiments, a biorefinery for producing biofuels may include a cane tissue fractionation system at a front end of the biorefinery, a sugar mill behind the cane tissue fractionation system, and a conversion unit for producing a renewable material.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the features, advantages, and principles of the invention. In the drawings:
The invention is directed to methods and systems for producing biofuels and other renewable materials using a lignocellulosic conversion process that involves tissue separation, as well as biofuel component compositions made according to such methods.
As used herein, the term “renewable material” preferably refers to a substance and/or an item that has been at least partially derived from a source and/or a process capable of being replaced at least in part by natural ecological cycles and/or resources. Renewable materials may broadly include, for example, chemicals, chemical intermediates, solvents, adhesives, lubricants, monomers, oligomers, polymers, biofuels, biofuel intermediates, biogasoline, biogasoline blendstocks, biodiesel, green diesel, renewable diesel, biodiesel blend stocks, biodistillates, biochar, biocoke, renewable building materials, and/or the like. As a more specific example, the renewable material may include, without being limited to, any one or more of the following: methane, ethanol, n-butanol, isobutanol, 2-butanol, fatty alcohols, isobutene, isoprenoids, triglycerides, lipids, fatty acids, lactic acid, acetic acid, propanediol, butanediol. In certain embodiments, the renewable material may include one or more biofuel components. For example, the renewable material may include an alcohol, such as ethanol, butanol, or isobutanol, or lipids.
The term “biofuel” preferably refers to components and/or streams suitable for use as a fuel and/or a combustion source derived at least in part from renewable sources. The biofuel can be sustainably produced and/or have reduced and/or no net carbon emissions to the atmosphere, such as when compared to fossil fuels. According to some embodiments, renewable sources can exclude materials mined or drilled. In some embodiments, renewable resources can include single cell organisms, multi-cell organisms, plants, fungi, bacteria, algae, cultivated crops, non-cultivated crops, timber, and/or the like. Biofuels can be suitable for use as transportation fuels, such as for use in land vehicles, marine vehicles, aviation vehicles, and/or the like. More particularly, the biofuels may include gasoline, diesel, jet fuel, kerosene, and/or the like. Biofuels can be suitable for use in power generation, such as raising steam, exchanging energy with a suitable heat transfer media, generating syngas, generating hydrogen, making electricity, and/or the like.
The term “fraction,” as used herein, preferably refers to one of the separable or separated constituents of a substance, such that all of the fractions together render the substance whole.
Lignocellulosic preferably broadly refers to materials containing cellulose, hemicellulose, lignin, juice, and/or the like, such as may be derived from plant material and/or the like. Lignocellulosic material may include any suitable material, such as sugarcane, sugarcane bagasse, energycane, energycane bagasse, rice, rice straw, corn, corn stover, maize, maize stover, wheat, wheat straw, sorghum, sorghum stover, sweet sorghum, sweet sorghum stover, arundo, cotton remnant, sugar beet, sugar beet pulp, soybean, rapeseed, jatropha, switchgrass, miscanthus, napier grass, other grasses, and hybrids of any of these materials. Lignocellulosic material may also include, in general, grasses legumes, forbs, cacti, timber, wood chips, softwoods such as pine and poplar, hardwoods such as eucalyptus, oak, and hickory, forest litter, wood waste, sawdust, paper, paper mill residue, paper waste, fruit waste, citrus waste, agricultural waste, municipal solid waste, any other suitable biomass material, and/or the like. According to some embodiments, the methods and systems described herein may apply to lignocellulosic materials other than or excluding corn, corn stover, maize, and maize stover.
Lignin preferably broadly refers to a biopolymer that may be part of secondary cell walls in plants, such as a complex highly cross-linked aromatic polymer that may covalently link to hemicellulose.
Hemicellulose preferably broadly refers to a branched sugar polymer composed mostly of pentoses, such as with a generally random amorphous structure and typically may include up to hundreds of thousands of pentose monomers.
Cellulose preferably broadly refers to an organic compound with the formula (C6H10O5)z where z includes any suitable integer. Cellulose may include a polysaccharide with a linear chain of several hundred to over ten thousand hexose monomers and may have a high degree of crystalline structure or may be amorphous, for example.
Juice preferably refers broadly to water and water-soluble molecules. Water may include bound and free water. Water-soluble molecules may include soluble sugars, sucrose, fructose, glucose, proteins, organic acids, minerals, salts, and the like.
As explained above, lignocellulosic biomass contains sugars in multiple forms, such as soluble sugars, starches, hemicellulose, and cellulose. Some of these sugars are relatively accessible, while others require multiple processing steps to prepare them for fermentation. By separating the lignocellulosic feedstock into multiple fractions based on the processing conditions required for each fraction, processes for producing renewable materials, such as biofuels, can be streamlined, resulting in capital minimization, reduced operating expenses, and increased yield.
In conventional processing of lignocellulosic biomass, the feedstock is typically pretreated under relatively harsh conditions in order to break down even the toughest of the lignocellulosic materials, such as the rind.
According to some embodiments herein, a more economical method (reduced capital or operating costs) for producing a renewable material may be achieved by separating lignocellulosic feedstock into two or more fractions, pretreating at least one of the fractions, and further treating the pretreated fraction or fractions to produce a renewable material. For instance, the juice may be processed along with the lignocellulosic leaves and pith and, because these components are easier to break down into sugars than the rind, they can be pretreated mildly and saccharified and fermented in high yield together. Mild pretreatment conditions may also result in reduced capital costs and/or reduced operating expenses compared to equipment required to carry out harsh pretreatment.
The cellular difference between pith and rind is that pith contains a majority of parenchyma cells with a small percentage of vascular bundles, namely pith contains more than 50% parenchyma cells on a dry weight basis and less than 50% vascular bundles on a dry weight basis. Rind, on the other hand, contains a mixture of different cell types, including epidermis, sclerenchyma, parenchyma, and vascular bundles, namely rind contains less than 50% parenchyma cells on a dry weight basis.
Example 1 below compares ethanol production of three different methods based on the methods illustrated in
Referring again to
An automated separation device, such as the KTC Tilby Cane Separation System, available from KTC Tilby Ltd. of Saanichton, British Columbia, may be used in conjunction with a trash separation/cane cleaning system to separate the lignocellulosic feedstock into any suitable number of fractions. Other systems for separating rind may be used as well, such as systems used for depithing in the production of quality fiber from bagasse.
For a grass crop such as sugarcane, maize, napiergrass, or sorghum, trash includes brown, senesced leaves; green, living leaves; and the apical internodes or growing point region at the top of the stalk.
In certain embodiments, the method may include both tissue separation and juice separation operations. In these embodiments, juice may be extracted from the lignocellulosic feedstock either before or after separating the lignocellulosic feedstock into two or more fractions.
The lignocellulosic feedstock may be separated into any suitable number of fractions, such as two, three, four, or five fractions. The lignocellulosic feedstock may be separated into even more fractions, in certain embodiments. According to some embodiments, one or more fractions may be enriched in water while one or more fractions may be depleted in water. The fraction or fractions depleted in water may be combusted.
For example, the lignocellulosic feedstock may be separated to generate a fraction that is enriched in cellulose, and/or a fraction that is enriched in hemicellulose, and/or a fraction that is enriched in lignin, and/or a fraction that is enriched in polysaccharides. In some embodiments, the lignocellulosic feedstock may be separated to generate a first fraction that is enriched in cellulose, and/or a first fraction that is enriched in hemicellulose, and/or a first fraction that is enriched in lignin, and/or a first fraction that is enriched in polysaccharides.
According to some embodiments, the lignocellulosic feedstock may be separated into at least two fractions, with the first fraction including between about 30% and about 85% primarily rind by dry weight, and the second fraction including between about 15% and about 70% primarily pith by dry weight. More particularly, the first fraction may include between about 30% and about 50% cellulose by dry weight, between about 15% and about 30% hemicellulose by dry weight, and between about 15% and about 25% lignin by dry weight, and the second fraction may include between about 15% and about 40% cellulose by dry weight, between about 9% and about 25% hemicellulose by dry weight, and between about 5% and about 19% lignin by dry weight.
According to some embodiments, each of the fractions may be pretreated. One or more, or even all of the fractions may be pretreated. The fractions may each be pretreated separately. Alternatively, two or more of the fractions may be pretreated together, either before or after separation.
As explained above, a harsh pretreatment process can be used to break down hard-to-digest components, such as fractions that include rind, while a mild pretreatment process can be used to break down components that are more easily digested, such as fractions that include pith and/or leaves. An empirical measure of pretreatment “harshness” is the “Combined Severity Factor,” which is calculated according to the following equation, wherein time is expressed in minutes and temperature is expressed in degrees Celsius: Log10(t×exp((T-100)/14.75))−pH (Schell, D. F.; Farmer, J.; Newman, M.; McMillan, J. D. Applied Biochemistry and Biotechnology, 2003, 105-108, pp 69-85). Similarly, the “Log Severity Factor” is calculated according to the following equation, wherein time is expressed in minutes and temperature is expressed in degrees Celsius: Log10(t×exp((T-100)/14.75)) (Kazi, K. M. F.; Jollez, P.; Chornet, E. Biomass and Bioenergy, 1998, 15, pp 125-141). However, these measurements are useful only for water-only and/or acid-catalyzed pretreatments.
The arbitrary terms “harsh” and “mild” are relative terms that depend greatly on the nature of the pretreatment (acid, base, solvent, etc.) and on the context of the process (enzymes, organisms, etc.). In embodiments involving two or more fractions that are pretreated separately, a “harsh” pretreatment process would have a higher log severity factor than a “mild” pretreatment process.
For dilute acid pretreatment, harsh pretreatment may include pretreatment with a combined severity factory of greater than 1.35 and mild pretreatment may include pretreatment with a combined severity factor of less than 1.35, as measured at 150° C., for 30 minutes, in 0.25% H2SO4. For hot water pretreatment and other pretreatments besides those employing dilute acid, harsh pretreatment may include pretreatment with a log severity factor of greater than 3 and mild pretreatment may include pretreatment with a log severity factor less than 3. For some feedstocks, harsh pretreatment may include pretreatment with a log severity factor of greater than 4 and mild pretreatment may include pretreatment with a log severity factor less than 4.
The pretreatment processes may include use of an ionic liquid, an acid, a base, an enzyme, and/or water. For example, the acid may include an inorganic acid, an organic acid, a mineral acid, a Bronsted acid, and/or a Lewis acid. More particularly, the acid may include sulfuric acid, hydrochloric acid, sulfonic acid, phosphoric acid, nitric acid, acetic acid, lactic acid, formic acid, and/or oxalic acid. When the pretreatment process involves using a base, the base may include an inorganic base, an organic base, a mineral base, a Bronsted base, and/or a Lewis base. More particularly, the base may include ammonia, ammonium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, lime, calcium hydroxide, and/or calcium oxide. In certain embodiments, the pretreatment may be carried out without heating the fraction or fractions. Conversely, in certain embodiments, the application of heat, such as in the form of steam, may be used in the pretreatment process.
During the processes described herein, one or more of the fractions may be converted to a sugar or sugars. The sugars may include, but are not limited to, sucrose, glucose, fructose, mannose, galactose, xylose, arabinose, hexose, pentose, cellobiose, and/or oligosaccharides. Any one or more of these sugars may be converted into a renewable material.
According to some embodiments, a cane fractionation system, such as the KTC Tilby Cane Separation System mentioned above, may be added at a front end of an existing sugar mill to increase capacity. As a result, this arrangement can increase the capacity of the existing sugar mill, as much as doubling it, while increasing the ethanol production over and above what would be expected with just increasing the throughput of the existing plant; producing up to three times the ethanol.
As used herein, the term “existing sugar mill” refers to a production facility that has been used as a sugar mill prior to adding a cane fractionation system or other tissue fractionation system to the facility to work in conjunction with the mill.
In
The wax cut 446 may be sent to a wax recovery section 464 either at a third party location or in-house, to recover the wax 466. The remaining fiber, or wax rind 468, may be sent to a roll mill 470 within the original sugar mill to be burned with the bagasse.
The rind 442 may be sent to the existing cane handling equipment in the plant, namely a shredder 472, a diffuser 474, and the roll mill 470, for sugar recovery. Any remaining bagasse may be sent to the boiler 462 for power production. The sugar may be sent to the existing sucrose recovery equipment, described below, or, alternatively, the sugar may be sent directly to a fermentation section 482 since the sugar will have a higher proportion of monomeric sugars than the juice 440.
The juice 440 may be sent to the existing sucrose production train in the sugar mill, namely to a clarification section 476, followed by an evaporation section 478, and a crystallization section 480, from which sugar 484 may be recovered and/or sent to a fermentation section 482. A yeast recovery section 486 connected to the fermentation section 482 prepares the sugar for a beer well 488. The same beer well 488 may serve the fermentation section 454 and the yeast recovery section 460 used to process the pith 444 and/or trash 448. From the beer well 488, the sugar is sent to a distillation section 490 where the renewable material 438 such as ethanol and vinasse 492 may be produced.
According to some embodiments, the invention may be directed to a renewable material made according to any of the methods described herein.
According to some embodiments, the invention may be directed to a biofuel made according to any of the methods described herein. For example, a biofuel component composition may be derived from a lignocellulosic material that was separated into a plurality of fractions, including between about 30% and about 85% of a first fraction that includes primarily rind by dry weight, and between about 15% and about 70% of a second fraction that includes primarily pith by dry weight, prior to converting one or more of the fractions into a biofuel component. The biofuel component may include an alcohol, such as ethanol and/or butanol.
According to some embodiments, the invention may be directed to a biorefinery for producing biofuels. The biorefinery may include a tissue separation unit for separating tissues of a lignocellulosic feedstock, a pretreatment unit for treating at least some of the separated tissues of the lignocellulosic feedstock, and a conversion unit for producing a renewable material from the separated tissues. As explained above, the pretreatment unit may include mild conditions for breaking down or depolymerizing fractions that are easily digested, or harsh conditions for breaking down or depolymerizing hard-to-digest components. The conversion unit may include a saccharification unit and/or a fermentation unit for converting the pretreated materials into biofuels.
Alternatively or additionally, a biorefinery may include a cane tissue fractionation system added to a front end of an existing sugar mill. The capital cost of adding a cane tissue fractionation system to a sugar mill would be comparable to installing a second train in the sugar mill plus the cost of the lignocellulosic ethanol equipment. The advantages of this arrangement include: 1) processing the pith and trash only for lignocellulosic conversion may require less severe hydrolysis conditions than processing the whole lignocellulosic material; 2) the juice may be cleaner, thereby minimizing expansion of the clarification system; 3) the sugars recovered from the existing diffuser/roll mill train may be higher in monomeric sugars and that stream may be sent directly to fermentation, thereby minimizing modifications to the sucrose processing unit. Furthermore, using this type of system may increase the throughput of the existing sugar mill, thus debottlenecking the existing mill.
In this example, ethanol production is compared among four different methods based on the general methods illustrated in
In the first method, based on the method shown in
In the second method, 100 kg of the feedstock (wet weight basis) may be fed to an automated trash separation unit. The leaves may be recovered from the trash separation unit, while the stalks are fed to a KTC Tilby Cane Separation System (KTC Tilby Ltd. of Saanichton, British Columbia), which produces separated rind and pith (containing juice). The rind may be discarded at this stage. The pith may be combined with the leaves, and these two components can be shredded together. The shredded material may be placed in a pretreatment reactor. The reactor contents can be heated to 120° C. and held at that temperature for 35 minutes. Additional treatments may be done at this stage to prepare the material for further processing. The pretreated slurry may then be cooled, transferred to another vessel, and treated with aqueous ammonia to raise the pH of the slurry to about 5. Additional treatments may be done at this stage to prepare the hydrolyzate for further processing. A cellulolytic enzyme cocktail can be added to the slurry and the temperature of the reaction maintained at 48° C. for 1 day. Next, the temperature of the mixture may be decreased to 30° C. and a yeast inoculum can be added to ferment the sugars into ethanol. Additional nutrients may be added at this stage. After 5 days the ethanol concentration in the beer can be measured by HPLC and the overall ethanol yield calculated. The beer may also be distilled to recover ethanol. The projected overall ethanol yield is shown in Table 1.
In the third method, 100 kg of the feedstock (wet weight basis) may be fed to an automated trash separation unit. The leaves may be recovered from the trash separation unit, while the stalks are fed to a KTC Tilby Cane Separation System (KTC Tilby Ltd. of Saanichton, British Columbia), which produces separated rind and pith (containing juice). The rind may be shredded and placed in a pretreatment reactor along with 35 g of sulphuric acid. The reactor contents may be heated to 170° C. and held at that temperature for 35 minutes. The pith can be combined with the leaves, and these two components can be shredded together. The shredded material may be placed in a pretreatment reactor. The reactor contents can be heated to 120° C. and held at that temperature for 35 minutes. Additional treatments may be done at this stage to prepare the material for further processing. The pretreated slurries may then be cooled, transferred to another vessel, and treated with aqueous ammonia to raise the pH of the combined slurry to about 5. Additional treatments may be done at this stage to prepare the hydrolyzate for further processing. A cellulolytic enzyme cocktail can be added to the slurry and the temperature of the reaction maintained at 48° C. for 1 day. Next, the temperature of the mixture can be decreased to 30° C. and a yeast inoculum added to ferment the sugars into ethanol. Additional nutrients may be added at this stage. After 5 days the ethanol concentration in the beer can be measured by HPLC and the overall ethanol yield calculated. The beer may also be distilled to recover ethanol. The projected overall ethanol yield is shown in Table 1.
In the fourth method, 100 kg of the feedstock (wet weight basis) may be fed to an automated trash separation unit. The leaves may be recovered from the trash separation unit, while the stalks are fed to a KTC Tilby Cane Separation System (KTC Tilby Ltd. of Saanichton, British Columbia), which produces separated rind and pith (containing juice). The pith may be further processed by passing it through a three-roller mill to substantially extract the juice from it. Imbibition water to aid in extraction may also be added at this stage. The rind may be shredded and placed in a pretreatment reactor along with 35 g of sulphuric acid. The reactor contents can be heated to 170° C. and held at that temperature for 35 minutes. The extracted pith may be combined with the leaves, and these two components can be shredded together. The shredded material can be placed in a pretreatment reactor. The reactor contents may be heated to 120° C. and held at that temperature for 35 minutes. Additional treatments may be done at this stage to prepare the material for further processing. The pretreated slurries may then be cooled, transferred to another vessel, and treated with aqueous ammonia to raise the pH of the combined slurry to about 5. Additional treatments may be done at this stage to prepare the hydrolyzate for further processing. A cellulolytic enzyme cocktail can be added to the slurry and the temperature of the reaction maintained at 48° C. for 1 day. Next, the temperature of the mixture was decreased to 30° C., the juice was added to the mixture, and a yeast inoculum can be added to ferment the sugars into ethanol. Additional nutrients may be added at this stage. After 5 days the ethanol concentration in the beer can be measured by HPLC and the overall ethanol yield calculated. The beer may also be distilled to recover ethanol. The projected overall ethanol yield is shown in Table 1.
As shown in Table 1, the three methods involving tissue separation, those shown in
In this example, separation of plant tissues is examined. Whole stalks of energycane (cultivar Ho 02-113), napier grass (PI 300086), and sugarcane (cultivar CP 03-1912) were harvested from the field in the late winter. Tissues of each crop were kept separate for the ensuing steps. The stalks were stripped of leaves and leaf sheathes by hand, and the leaves and leaf sheathes were collected and weighed. The stripped stalks were cut into 1-foot segments and split in half. The pith tissue on the inside of the stalk was stripped away from the rind tissue on the outside of the stalk, and each tissue was collected separately and weighed. Each collected tissue was then milled in a Dedini cane disintegrator, available from Dedini Industrial De Base, Brazil (www.dedini.com.br). The disintegrated material was tested for moisture using a halogen moisture balance. The weights, moisture contents, and dry weights of the collected tissues are shown in Table 2.
In this example, pretreatment of separated plant tissues is examined. Separated energycane pith and rind as prepared in Example 2 were subjected to pretreatment according to the following procedure. Wholestalk energycane prepared by milling in a Dedini cane disintegrator was also subjected to pretreatment according to the following procedure. The milled feedstock was washed with four successive volumes of deionized water at 70° C., then pressed to a consistency of approximately 30% dry solids. Next, sufficient pressed feedstock to supply 40.0 g dry weight of biomass was added to a microwave reactor vessel. Aqueous sulphuric acid (50.0 ml, 1% w/w) was added, along with enough deionized water to bring the overall dry solids loading of the pretreatment reaction mixture to 16.7%. The contents of the vessel were mixed well, and the vessel was sealed in the microwave reactor. In the microwave, the pretreatment reaction mixture was heated rapidly to 160° C. and held at that temperature for 30 minutes. The reaction mixture was then cooled to 60° C. The liquids in the reaction mixture were analyzed by HPLC, and the liquid hydrolyzate composition was reported in Table 3.
In this example, pretreatment and enzymatic hydrolysis of separated plant tissues is examined. Separated sugarcane pith (4C, cultivar CP 03-1912), energycane rind (4B, Ho 02-113), and energycane leaves (4D, Ho 02-113) as prepared in Example 2 were subjected to pretreatment according to the following procedure. Wholestalk energycane (4A, Ho 02-113) prepared by milling in a Dedini cane disintegrator was also subjected to pretreatment according to the following procedure. The milled feedstock was washed with four successive volumes of deionized water at 70° C., then pressed to a consistency of approximately 30% dry solids. Next, sufficient pressed feedstock to supply 15.0 g dry weight of biomass was added to a microwave reactor vessel. Aqueous sulphuric acid (37.5 ml, 1% w/w) was added, along with enough deionized water to bring the overall dry solids loading of the pretreatment reaction mixture to 9.1%. The contents of the vessel were mixed well, and the vessel was sealed in the microwave reactor. In the microwave, the pretreatment reaction mixture was heated rapidly to 160° C. and held at that temperature for 30 minutes. The reaction mixture was then cooled to room temperature. The liquids in the reaction mixture were analyzed by HPLC, and the liquid hydrolyzate composition is reported in Table 4.
The solids remaining in the hydrolyzed biomass were collected by filtration and washed thoroughly with water. A portion of the washed solids were enzymatically digested for 72 hours at 5% solids loading, pH 5.5, and 35° C. in a reaction mixture containing 38 μl Biocellulase W (Kerry Biosciences), β-glucosidase (1 mg/g of washed solids), 50 mM sodium citrate, 5 mM NaN3, and 50 μg/ml kanamycin. The sugars released by enzymatic hydrolysis were measured at 24, 48, and 72 hours by HPLC. The overall sugar yields (as a percentage of the theoretical yield of sugar from the washed, pressed feedstock) from each step are reported in Table 5.
Thus, the methods herein using pretreatment and enzymatic hydrolysis of separated plant tissues may result in a glucose yield from acid hydrolysis of at least 4%, or at least 7%, or at least 14%, and/or a glucose yield from enzymatic hydrolysis of at least 50%, or at least 64%, or at least 67%, and/or an overall glucose yield of at least 54%, or at least 75%, or at least 79%. Additionally, the methods herein using pretreatment and enzymatic hydrolysis of separated plant tissues may result in a xylose yield from acid hydrolysis of at least 68%, or at least 80%, or at least 83%.
Additional results are provided in
In this example, washed and size-reduced samples of whole energycane, pith, and rind were prepared. Whole stalks of energycane (cultivar Ho02-113) were stripped of leaves (including leaf sheathes). The stalks were cut into billets 6″ to 12″ long. Some of these billets were prepared by passing them through a mechanical KTC Tilby Cane Separation System (KTC Tilby Ltd. of Saanichton, British Columbia), which produces separated rind and pith (containing juice). Each of the fractions was frozen in storage until the next steps were performed. The pith was washed with four successive volumes of deionized water at 70° C., then pressed to a consistency of approximately 30% dry solids. The rind was cut into short segments <1″ long and was size reduced to short fibers in a blender with added water. The rind fibers were washed with four successive volumes of deionized water at 70° C., then pressed to a consistency of approximately 30% dry solids. The whole energycane billets were cut into short segments <1″ long and were size reduced in a blender with added water. The resulting cane slurry was washed with four successive volumes of deionized water at 70° C., then pressed to a consistency of approximately 30% dry solids. The washed pith, rind, and whole cane samples were stored in a freezer until use.
In this example, pretreatment and enzymatic hydrolysis of mechanically separated plant tissues is examined. Washed pith, rind, and whole cane prepared by the methods of Example 5 were subjected to pretreatment according to the following procedure. Sufficient pressed feedstock to supply 15.0 g dry weight of biomass was added to a microwave reactor vessel. Enough deionized water was added to bring the overall dry solids loading of the pretreatment reaction mixture to 9.1%. The contents of the vessel were mixed well, and the vessel was sealed in the microwave reactor. In the microwave, the pretreatment reaction mixture was heated rapidly to 180° C. or 190° C. depending on the entry and held at that temperature for 30 minutes. The reaction mixture was then cooled to room temperature. The liquids in the reaction mixture were analyzed by HPLC, and the liquid hydrolyzate composition are reported in Table 6.
The solids remaining in the hydrolyzed biomass were collected by filtration and washed thoroughly with water. A portion of the washed solids were enzymatically digested for 72 hours at 5% solids loading, pH 5.0, and 50° C. in a reaction mixture containing Biocellulase TR1 (76 μl, Kerry Biosciences), β-glucosidase (2 mg/g of washed solids), 50 mM sodium acetate, 5 mM NaN3, and 50 μg/ml kanamycin. The sugars released by enzymatic hydrolysis were measured at 24, 48, and 72 hours by HPLC. The overall sugar yields (as a percentage of the theoretical yield of sugar from the washed, pressed feedstock) from each step are reported in Table 7.
Thus, the methods herein using pretreatment and enzymatic hydrolysis of mechanically separated plant tissues may result in a glucose yield from pretreatment of at least 1.2%, or at least 1.5%, or at least 2%, and/or a glucose yield from enzymatic hydrolysis of at least 48%, or at least 69%, or at least 71%, and/or an overall glucose yield of at least 50%, or at least 71%, or at least 72%. Additionally, the methods herein using pretreatment and enzymatic hydrolysis of mechanically separated plant tissues may result in a xylose yield from pretreatment of at least 12%, or at least 13%, or at least 38%, and/or a xylose and xylooligomers yield from pretreatment of at least 62%, or at least 63%, or at least 64%.
Additional results are provided in
In this example, enzymatic hydrolysis of mechanically separated plant tissues is examined. Washed pith (7C), rind (7B), and whole cane (7A) prepared by the methods of Example 5 were subjected to enzymatic hydrolysis for 72 hours at 5% solids loading, pH 5.5, and 35° C. in a reaction mixture containing Biocellulase TR1 (38 μl, Kerry Biosciences), β-glucosidase (1 mg/g of washed solids), 50 mM sodium citrate, 5 mM NaN3, and 50 μg/ml kanamycin. The sugars released by enzymatic hydrolysis were measured at 24, 48, and 72 hours by HPLC. The overall sugar yields at 72 hours (as a percentage of the theoretical yield of sugar from the washed, pressed feedstock) are reported in Table 8.
Thus, the methods herein using enzymatic hydrolysis of mechanically separated plant tissues may result in a glucose yield of at least 4%, or at least 29% and/or a xylose yield of at least 1.5%, or at least 3.9%.
Additional results are provided in
It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed structures and methods without departing from the scope or spirit of the invention. Particularly, descriptions of any one embodiment can be freely combined with descriptions or other embodiments to result in combinations and/or variations of two or more elements or limitations. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US13/38783 | 4/30/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61640503 | Apr 2012 | US |
