U.S. patent application number 10/340877 was filed with the patent office on 2003-09-18 for process for obtaining bio-functional fractions from biomass.
Invention is credited to Thorre, Doug Van.
Application Number | 20030176669 10/340877 |
Document ID | / |
Family ID | 24457198 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030176669 |
Kind Code |
A1 |
Thorre, Doug Van |
September 18, 2003 |
Process for obtaining bio-functional fractions from biomass
Abstract
The present invention includes a process for extracting
bio-functional materials from biomass. The method comprises
providing biomass and subjecting the biomass to substantially
instantaneous pressurization and depressurization to separate
bio-functional materials, such as cellulose, hemicellulose, and
lignin from the biomass.
Inventors: |
Thorre, Doug Van;
(Minneapolis, MN) |
Correspondence
Address: |
Schwegman, Lundberg,
Woessner & Kluth, P.A.
P.O. Box 2938
Minneapolis
MN
55402
US
|
Family ID: |
24457198 |
Appl. No.: |
10/340877 |
Filed: |
January 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10340877 |
Jan 10, 2003 |
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PCT/US01/41322 |
Jul 10, 2001 |
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Current U.S.
Class: |
536/1.11 ;
162/238; 536/123; 536/57 |
Current CPC
Class: |
C08B 1/00 20130101; C08B
37/006 20130101; D21C 5/00 20130101; Y10S 435/80 20130101; C08H
8/00 20130101 |
Class at
Publication: |
536/1.11 ;
536/57; 536/123; 162/238 |
International
Class: |
C08B 016/00; C07H
001/00; C08B 037/00; D21C 007/12 |
Claims
What is claimed is:
1. A method for extracting bio-functional and bio-responsive
fractions from biomass, comprising: providing biomass; treating the
biomass with saturated steam at a time and temperature effective to
extract bio-functional and bio-responsive fractions; and rapidly
depressurization the biomass and steam.
2. The method of claim 1 wherein the biomass is subjected to
pressurization at a temperature of about 390 to 460 degrees
Fahrenheit.
3. The method of claim 1 wherein the biomass is subjected to
pressurization for a time ranging from 2 minutes to 4 hours.
4. A process for extraction of bio-functional materials from
biomass, comprising: determining quantities of the bio-functional
materials in the living biomass; harvesting the biomass; subjecting
the biomass to saturated steam at a time and temperature effective
to extract the bio-functional materials; and rapidly depressurizing
the biomass to extract the bio-functional materials.
5. A bio-functional material produced by the method of claim 1 or
claim 4.
6. A native cellulose produced by the method of claim 1.
7. A native cellulose produced by the method of claim 4.
8. A biomass extract consisting essentially of a water soluble
fraction comprising pectin.
9. A biomass extract consisting essentially of an insoluble
fraction comprising cellulose, protein and lignin.
10. The biomass extract of claim 8 wherein the pectin fraction is
30 weight percent of the biomass.
11. The biomass extract of claim 9 wherein the cellulose, protein,
lignin fraction is 70 weight percent of the biomass.
12. A bio-refined extract of biomass consisting of an insoluble
fraction comprising pectin and arabinogalactan.
13. A bio-refined extract of biomass, derived from the insoluble
fraction of claim 12, comprising L-arabinose.
14. The bio-refined extract of biomass, derived from the insoluble
fraction of claim 12, comprising galacturonic acid.
15. The bio-refined extract of biomass, derived from the insoluble
fraction of claim 12, comprising xylose.
16. An insoluble bio-refined extract, obtained from the fraction of
claim 9, comprising cellulose.
17. A bio-refined extract consisting of monomers, oligomers, and
polymers of carboxymethyl cellulose.
18. A bio-refined extract consisting of protein isolates.
19. A bio-refined extract consisting of coniferyl alcohol.
20. A process for extracting a stereoisomer from biomass,
comprising: providing biomass; subjecting the biomass to
substantially instantaneous pressurization and de-pressurization in
a manner effective to separate lignin, hemicellulose and cellulose
in the biomass; hydrolyzing the hemicellulose to form hemicellulose
hydrolysates; and separating one or more stereoisomers from the
hemicellulose hydrolysates using adsorption.
21. The process of claim 1 and further comprising reducing size of
the biomass prior to pressurization.
22. The process of claim 1 and further comprising compacting the
biomass prior to pressurization.
23. The process of claim 1 wherein the biomass provided is one or
more of wood, beets, corn, soy, wheat, and plant biomass.
24. The process of claim 1 wherein the stereoisomer separated is
L-arabinose.
25. The process of claim 1 wherein the biomass is subjected to
pressurization at a temperature of about 390 to 460 degrees
Fahrenheit.
26. The process of claim 1 wherein the biomass is subjected to
pressurization for not more than about 10 minutes.
27. The process of claim 2 wherein the biomass is reduced to a size
of sawdust.
28. The process of claim 1 and further comprising feeding the
biomass for pressurization continuously.
29. The process of claim 1 and further comprising adding moisture
to the biomass before pressurization.
30. The process of claim 1 wherein the hydrolysis occurs in a
reactor/static mixer.
31. The process of claim 11 wherein the hydrolysis occurs at about
329 to 347 degrees Fahrenheit, under pressure.
32. The process of claim 11 wherein sodium hydroxide is added to
the static mixer in a flowpath that is counter-current to the flow
of hemicellulose.
33. The process of claim 12 wherein the stereoisomer separation is
performed with co-polymer beads.
34. A system for obtaining monosaccharides, oligosaccharides and
polysaccharides from biomass, comprising: a mechanism for
substantially instantaneously pressurizing and de-pressurizing
biomass to separate the biomass into hemicellulose, cellulose, and
lignin; a heater for heating the hemicellulose to liquefy the
hemicellulose; a reactor/mixer for mixing a sodium hydroxide with
hemicellulose and for making hemicellulose hydrolysates; and a
mechanism for selectively separating a hemicellulose hydrolysate
based upon the component's stereoisomeric identity.
35. The system of claim 15 wherein a biomass comprises sugar beet
pulp.
36. The system of claim 15 wherein the hemicellulose product does
not enter a glassy state but is liquefied.
37. The system of claim 15 wherein the hemicellulose product is
free of caramelized hemicellulose product.
38. The system of claim 15 wherein the sodium hydroxide is in the
aqueous phase.
39. The system of claim 15 wherein the hemicellulose hydrolysates
comprise d-arabinose, l-arabinose, d-xylose, l-xylose, d-glucose,
l-glucose, and any other racemic carbohydrates.
40. The system of claim 15 wherein the hemicellulose hydrolysates
comprise polygalacturonic acid.
41. The system of claim 15 wherein the hemicellulose hydrolysates
comprise any backbone polymer.
42. The system of claim 15 and further comprising a mechanism which
receives the hemicellulose hydrolysates.
43. The system of claim 15 wherein the hemicellulose hydrolysates
are separated into optically pure products.
44. A process for extracting L-arabinose from sugar beet pulp,
comprising: providing sugar beet pulp; subjecting the sugar beet
pulp to substantially instantaneous pressurization and
de-pressurization in a manner effective to separate lignin,
hemicellulose and cellulose in the sugar beet pulp; hydrolyzing the
hemicellulose to form hemicellulose hydrolysates; and separating
L-arabinose from the hemicellulose hydrolysates using
chromatography.
45. The process of claim 24 wherein the L-arabinose is produced at
a rate of at least 1000 pounds per day.
46. The process of claim 1 and further comprising extracting
derivatives and substituents from cellulose and lignin.
47. The process of claim 1 and further comprising crystallizing the
separated product.
48. The process of claim 27 wherein the crystallizing is performed
using a low intensity ultrasonic agitation.
Description
RELATED APPLICATIONS
[0001] This application is a continuation under 35 U.S.C. 111(a)
from International Application No. PCT/US01/41322 filed Jul. 10,
2001 and published in English as WO 02/04084 on Jan. 17, 2002,
which claims priority from U.S. application Ser. No. 09/613,411
filed Jul. 10, 2000, which applications and publication are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a method for extracting
bio-functional fractions from biomass. The present invention also
relates to a method for extracting and purifying stereoisomers from
biomass. The present invention also relates to a method for
extracting and purifying L-arabinose from sugar beet pulp.
[0003] Extraction and purification of biologically active materials
from biomass has been a complicated and inefficient endeavor.
Extraction has traditionally employed harsh solvents; created
intermediate reaction products and physical conditions very
different from conditions forming the extracted chemicals in the
first place. Because of these harsh conditions, there has been some
question as to whether complex molecules such as native cellulose
have ever really been extracted in a way that preserves the native
cellulose structure.
[0004] This concern extends to the separation and purification of
optically pure bio-functional materials. Drug and fine chemical
feed stocks have been produced to exacting physical and chemical
purity standards or chirality. However, little regard has been
given to optical purity. Achieving optical purity requires
identifying feed stock components that have stereoisomers and
selecting D- or L-forms of chemicals that have stereoisomers. The
D- and L-forms are known as stereoisomer pairs, i.e. right and left
handed pairs. Stereoisomers are molecules that are identical in
atomic constitution, and that have, in some instances essentially
identical physical and chemical properties. The stereoisomeric
pairs differ in three dimensional arrangement of atoms, optical
rotation, and chemical properties.
[0005] One type of stereoisomer pair is an enantiomer. An
enantiomer is a stereoisomer pair with at least one asymmetric
center. Individual stereoisomers of an enantiomer are mirror images
of each other. Drugs tend to have enantiomers that have activity
which is biologically distinguishable. In some instances,
individual enantiomers of drugs have distinguishable biological
activity. Naturally occurring, optically impure, or racemic
mixtures of stereoisomers have been used as feed stocks in the
pharmaceutical and fine chemical industries. In many instances, the
quality of the final product has been insensitive to the optical
purity of the feedstock. However, in some cases, the chemical and
optical purity of the final product has depended, in part, upon the
optical purity of the feed stock.
[0006] One stereoisomeric drug having one enantiomer which shows a
different biological activity in humans than the other enantiomer
is d,l-propranolol. l-propranolol acts as a beta-blocker.
d-propranolol lacks such activity.
[0007] In some instances, one of the enantiomers is toxic while the
other enantiomer is benign. For instance, when a d-isomer was
removed from d,l-carnitine in a drug composition, doctors could no
longer observe symptoms of myasthenia gravis. Symptoms had been
observed, however, in patients taking the racemic mixture of d,l
carnitine.
[0008] One other example is thalidomide. It is well known that
ingestion of R,S-thalidomide in the 1950's by pregnant women led to
the birth of children with phocomelia and other embryopathies. It
was subsequently found that the R enantiomer of thalidomide is
teratogenic and toxic in an animal model while the S enantiomer of
thalidomide is neither teratogenic nor toxic in that model.
Unfortunately, no benefit is found in humans of using the S
enantiomer of thalidomide over the R enantiomer because humans
morph the pure S form to a racemic mixture of R,S-thalidomide. It
is still unknown which enantiomer of thalidomide is toxic in
humans. Therefore, thalidomide use is prohibited in most cases in
the United States.
[0009] Because enantiomers have radically different biological
activity, the FDA has developed a set of rules governing the
development of stereoisomeric drugs. These rules can be found at
the FDA website. Specifically, the FDA requires that the
enantiomeric composition of a drug should be known. That is, the
stereochemical identity, strength, quality, and purity should be
known in the final product. The FDA has further stated that
"appropriate manufacturing and control procedures should be used to
assure stereoisomeric composition of a product, with respect to
identity, strength, quality and purity." Thus, pharmaceutical
feedstocks, and fine chemical feedstocks used to formulate products
which come under the FDA regulatory power, must be produced with
utmost concern for the chirality of the molecules.
[0010] One group of chemicals that is rich in stereoisomers is the
group comprising carbohydrates. Conventional carbohydrate chemistry
for extracting sugars from sugar cane pulp, bagasse, or sugar beet
biomass requires using large amounts of caustic and hydrochloric
acid to hydrolyze the cellulose and hemicellulose polymer backbone.
In the extraction, the mixed carbohydrate biomass is initially
placed into a caustic solution where it forms ellipsoidal
aggregates. The typical formulation calls for approximately 100
pounds of caustic for each pound of hemicellulose/cellulose
carbohydrate mixture. This extraction step is accompanied by
disposal problems. Since the ellipsoidal aggregates are only weakly
permeable to aqueous solutions, the hydrolysis process must be
performed at high temperatures and for an extended period of
time.
[0011] What occurs is thermal degradation of the exterior of the
ellipsoidal aggregate before the hydrolysis reaction has traversed
the radius of the aggregate. The degradation results in a
diminished yield and a need to separate the degraded carbohydrate
from the hydrolyzed hemicellulose/cellulose mixture. Conventional
extraction requires a significant destruction of raw material due
to thermal decomposition of the carbohydrate and environmental
damage resulting from disposal of caustic and acidic process
chemicals.
SUMMARY OF THE INVENTION
[0012] One embodiment of the present invention includes a method
for extracting biofunctional fractions from biomass. The method
comprises fractionating biomass by water content; that is,
biofunctional fractions with the highest water content are
fractionated first and biofunctional fractions with the lowest
water content are fractionated last. Fractionation in this way
produces fractions of monomers, oligomers, and polymers with a
physical and chemical structure that has a minimal amount of damage
and a high degree of bio-functionality and bio-response. The
extraction method utilizes excipient starting materials such as
corn plants, wheat plants, soy plants, beet plants, cranberry
plants, and other agricultural plants. The extraction method has a
capability of producing bio-functional materials from biomass in
high yield, with a minimal amount of chemical or physical
alteration from the native state.
[0013] For other embodiments, the bio-functional materials produced
by exposure to saturated steam and sudden decompression are then
heated and rapidly hydrolyzed in a static mixer. With this step, a
material such as hemicellulose, undergoes a phase transition, from
a solid to a non-Newtonian fluid.
[0014] One other embodiment of the present invention includes a
process for extracting a stereoisomer from biomass. The process
includes providing biomass and subjecting the biomass to
instantaneous pressurization and depressurization in a manner
effective to separate lignin, hemicellulose and cellulose in the
biomass. The process also includes hydrolyzing the hemicellulose to
form hemicellulose hydrolysates. One or more stercoisomers is
separated from the hemicellulose hydrolysates using
chromatography.
[0015] Another embodiment of the present invention includes a
system for obtaining monosaccharides, oligosaccharides and
polysaccharides from biomass. The system comprises a mechanism for
substantially pressurizing and depressurizing biomass to separate
the biomass into hemicellulose, cellulose and lignin. The system
also includes a heater for heating the hemicellulose. The system
further includes a reactor/mixer for mixing sodium hydroxide with
hemicellulose and for making hemicellulose hydrolysates. The system
additionally includes a mechanism for selectively separating a
hemicellulose hydrolysate based upon the component's exact
sterisomeric identity.
[0016] One other embodiment of the present invention includes a
process for extracting L-arabinose from sugar beet pulp. The
process comprises providing sugar beet pulp and subjecting the
sugar beet pulp to substantially instantaneous pressurization and
depressurization in a manner effective to separate lignin,
hemicellulose and cellulose in the beet pulp. The process also
includes hydrolyzing the hemicellulose to form hemicellulose
hydrolysates. L-arabinose is separated from the hemicellulose
hydrolysates using chromatography.
BRIEF DESCRIPTION OF THE FIGURES
[0017] FIG. 1 is a schematic view of one embodiment of the process
of the present invention.
[0018] FIG. 2A illustrates one embodiment of an SMB used in the
process of the present invention.
[0019] FIG. 2B illustrates one embodiment of an SMB used in the
process of the present invention.
[0020] FIGS. 3A and 3B illustrate feed valves used in the SMB
process.
[0021] FIG. 4 is a schematic view of one process embodiment of the
present invention
DETAILED DESCRIPTION OF THE INVENTION
[0022] One embodiment of the present invention includes a method
for extracting biofunctional fractions such as monomers, oligomers,
and polymers from biomass in a manner effective for maintaining a
bio-functionality and bio-response that is substantially the same
as the materials had prior to extraction. The method includes
subjecting a biomass substrate to saturated steam pressurization
and depressurization. The process of pressurization and
depressurization with saturated steam fractionates biofunctional
materials by water content--from fractions having the highest water
content to fractions having the lowest water content. In one
embodiment, the order of fractionation is extractibles such as
terpenes, lignin, pectin, hemicellulose and native cellulose. What
is meant be bio-functional and bio-reactive is that the tertiary
and quaternary structures of these materials are not destroyed.
[0023] Once extracted, the fractions are cooled to ambient
temperature. For some embodiments, the fractions are kept hot for
further processing. With this method, there is a minimal loss in
biofunctionality and bioresponse, as compared to traditional wet
chemistry methods of separation. What is remarkable and unexpected
is that this biofunctionality and bioresponse is achieved without
complicated chemical treatment. Separation without loss of
functionality and response is achieved by a one step steam
pressurization/depressurization. What is also remarkable is that
the extraction occurs with virtually any biomass feedstock.
Pretreatment of biomass is minimal and is typically limited to size
reduction.
[0024] It is believed that with this treatment, substantially
native physical and chemical properties and structure are preserved
for molecules such as native cellulose. It is also believed that
with this treatment, a mass balance can be performed over a plant
for virtually all of the bio-functional materials within the plant.
Products extracted are in a concentration and of a reactivity
within a range of what is predictable from a mass balance.
[0025] The present invention also comprises a process for
extracting, separating, and purifying individual stercoisomers from
biomass. The process, illustrated schematically at 10 in FIG. 1,
comprises providing a source of biomass 12, subjecting the biomass
to saturated steam pressurization/depressurization 14 that
increases surface area of the biomass and that permits separation
of lignin, cellulose, and hemicellulose components from the
biomass, heating hemicellulose 16 separated from the biomass in
order to hydrolyze the hemicellulose and obtain hydrolyzed
monomers, oligomers and polymers, and separating polymers,
oligomers, and monomers from hydrolyzed hemicellulose 18. While
hydrolysates are described, it is understood that the process of
the present invention is usable to extract, separate and purify
substituents and derivatives of cellulose, hemicellulose and
lignin. For instance, cellulose derivatives such as carboxy methyl
cellulose and hydroxypropyl cellulose can be obtained using the
process of the present invention. Confusal alcohols are also
obtainable. Stereoisomers of the monomers are further extracted
using chromatographic methods 20.
[0026] The present invention achieves high yields of stereoisomers,
such as L-arabinose, using physical processes in addition to
hydrolytic reactions, rather than exclusively conventional, water
based, chemical extraction techniques. It has surprisingly been
found that employing heat and pressure in treating biomass, such as
sugar beet pulp or wood pulp, increases production rates and
percent yield of stereoisomers as compared to conventional, water
based, chemical extraction processes.
[0027] As used herein, "simple sugars" refer to monosaccharides and
oligosaccharides which are not decomposed into smaller sugars upon
hydrolysis. Monosaccharides include pyranoses and furanoses.
Monosaccharides are also classified according to the number of
carbons in the molecule; for example, d,l-arabinose is a
heptose.
[0028] As used herein, "complex sugars" refer to polysaccharides
which are carbohydrates of high molecular weight capable of being
hydrolyzed into a large number of monosaccharide units. Typical
polysaccharides are cellulose, lignin, hemicellulose, starch and
pentosan.
[0029] An oligosaccharide is a simple polysaccharide with a known
number of constituent monosaccharide units, such as 1 to 10
monomers.
[0030] The term "biomass" as used herein refers to plant materials
including, but not limited to sugar beet pulp, bagasse, straw, corn
stalks, corn cobs, grain husks, grass, and wood. Biomass in the
form of plant materials includes cellulose and hemicellulose, both
of which are polysaccharide, and lignin. Cellulose molecules are
linear and unbranched glucose polymers with a high degree of
polymerization between 10 and 10.sup.6. Cellulose has a strong
propensity to form both intermolecular and intramolecular hydrogen
bonds. Cellulose is stable against degradation under most physical
and chemical conditions. Hemicellulose comprises
heteropolysaccharides which are formed by a variety of different
monomers. Most commonly the monomers are glucose, galactose,
mannose, xylose and arabinose. Hemicellulose molecules have a
degree of polymerization of about 10.sup.6. Biomass also includes
entire plants, including stalk, roots, fruit, and so forth. The
entire plants include but are not limited to corn plants, sugar
beet plants, soy plants, wheat plants, cranberry plants, potato
plants, sorghum plants, alfalfa plants, flax plants, and so
forth
[0031] The term "feedstock" as used herein refers to any material
supplied to a device, machine, or processing plant.
[0032] The biomass used in the process of the present invention may
be obtained from a variety of processes that extract products from
wood, sugar beets, corn, soy, wheat and any other plant matter. The
biomass is subjected to a particle size of reduction to a size of
chips or finer, such as a size of sawdust, using conventional
particle reduction equipment. The smaller the size, the easier it
is to mechanically handle the biomass. Smaller sized particles have
a greater surface area and are more amenable to chemical reaction.
Also, desired processing temperatures are reached more rapidly when
using smaller particles.
[0033] In one embodiment, the biomass is fed to a hopper. The
biomass may optionally be sprayed with water either before transfer
to the hopper or while in the hopper. The biomass exits from the
bottom of the hopper into a conveying feeder which contains a
conveying mechanism such as a feed screw driven by a variable feed
drive. The feed screw or other conveying mechanism feeds the
material into a compacting feed tube and then into a pressurized
retention tube, where the biomass particles are formed into a solid
plug of material. The solid plug is compressed by surface pressures
of up to 2000 psi.
[0034] The biomass is mechanically compacted prior to its
introduction into the digester. The biomass is desirably in a
moistened condition. The mechanical compaction removes air from the
material prior to its introduction to steam pressurization. Air is
undesirable because oxygen in the air tends to oxidatively degrade
the biomass. Air also exerts a partial pressure and retards
temperature and pressure equalization within the reactor.
[0035] Steam pressurization, within the pressurized reaction
vessel, is typically operated with automatic pressure and
temperature control systems. The partial pressure of any air
pockets decreases steam pressure and temperature in the reactor
below a preselected value. Compaction, followed by processing
conditions discussed below, causes a degree of fibrillation of the
biomass. Fibrillation of biomass assists in the heat transfer
within and around the material.
[0036] Next, the biomass particles are disintegrated by steam
pressure treatment and defibrination. In particular, the particles
are treated with saturated steam at a temperature of from about 160
to 230 degrees Centigrade for a period of time from 2 minutes to 4
hours. The biomass is disintegrated by this steam treatment. In
general, the lower the temperature used, the longer the duration of
treatment should be. Thus, for some extractions, it is desirable to
treat a biomass at 160 degrees Centigrade for about 4 hours. For
other extractions, it is desirable to treat a biomass for 2 minutes
at 230 degrees Centigrade.
[0037] This steam treatment separates fractions within biomass by
most to least water content. The fractions are separated as
extractables such as terpenes, fatty acids and so forth, lignin,
pectin, hemicellulose and native cellulose. This steam treatment
yields fractions at yields that are predictable by a mass balance
of the biomass. In other words, the steam treatment and extraction
of the present invention permits a user to ascertain
bioactive/biofunctional materials present in living biomass and to
extract the bioactive/biofunctional materials in quantities that
approach or are substantially the same as the materials are present
in the native biomass.
[0038] Biomass disintegrated this way is then, subsequently, for
some embodiments, lixiviated with an aqueous solution of alkali.
The concentration of NaOH is typically no greater than about 4% by
weight.
[0039] The biomass mixture contains between 1 and 20 grams of water
per gram of dry biomass and preferably about 16 grams of water per
gram of dry biomass. In one embodiment the biomass mixture contains
between 2 and about 50 grams of calcium hydroxide per 100 grams of
dry biomass and preferably contains 30 grams of calcium hydroxide
per 100 grams of dry biomass. In another embodiment the biomass
mixture contains between 2 and 50 grams of alkali, hydroxide of
sodium or hydroxide of potassium, per 100 grams of dry biomass.
[0040] The steam pressure treatment is performed in either a
continuous stream or a batch type steam pressure reactor. In one
embodiment, the reactor is manufactured by Stake Technology Ltd. Of
Ottawa, Canada. One particular device is described in U.S. Pat. No.
4,136,207, which issued Jan. 23, 1979, and which is herein
incorporated by reference. The steam pressure treatment is
performed in the reactor vessel. The reactor vessel is maintained
at a pressure that is between about 200 and 450 psig. The
temperature in the reactor is maintained between about 390.degree.
F. and 460.degree. F. The biomass is fed intermittently for some
embodiments and continuously for other embodiments. By varying the
biomass stream but maintaining the reactor vessel conditions, the
method of the present invention introduces an efficiency to the
process, by avoiding ramp up and ramp down conditions within the
reactor vessel.
[0041] The biomass is introduced into the reaction vessel in a
manner that forms a solid plug at the inlet of the vessel. In one
embodiment, the solid plug is formed in a device, such as a
retention tube. The biomass plug prevents a loss of pressurization
in the vessel. The combination of the biomass plug and constant
pressurization permits instantaneous steam penetration of the
biomass within the reaction vessel, and thus permits better control
of processing times.
[0042] The biomass is processed at the steam temperatures described
for a period of at least about 15 seconds and for some embodiments,
at least about 5 minutes. The maximum time is about one hour.
[0043] After cooking, the biomass is cooled and depressurized
substantially instantaneously. The biomass is in a moisture
saturated condition. The biomass is subjected to sudden and
substantially instantaneous decompression and adiabatic expansion,
e.g. by discharging a small quantity of cooked biomass into ambient
conditions.
[0044] The process of instantaneous pressurization and
de-pressurization separates the biomass into components of lignin,
cellulose and hemicellulose. The hemicellulose product is separated
from the cellulose product and lignin product by techniques known
in the art. It is further contemplated that the cellulose product
is separated from the lignin product by techniques in the art.
[0045] Once the hemicellulose is extracted from the biomass, the
hemicellulose, for some embodiments, is heated in a steam heater,
such as a Komax steam heater and then is hydrolyzed in a static
mixer, such as a Komax reactor/static mixer, manufactured by Komax
Systems, Inc., of Long Beach, Calif. One reactor/static mixer
embodiment is described in U.S. Pat. No. 6,027,241, which is herein
incorporated by reference. The reactor/static mixer is, in one
embodiment, constructed so that an additive, such as sodium
hydroxide is added countercurrent to the main fluid stream. The
heater and mixer comprise a heater-mixer system.
[0046] Within the reactor, at approximately 329.degree. F.
hemicellulose undergoes a phase transition, depending upon the
moisture content, from a solid to a non-Newtonian fluid, somewhat
like tooth paste. At temperatures higher than approximately
500.degree. F., depending upon moisture content, the hemicellulose
begins to pyrolize. Furthermore, the xylan component of the
hemicellulose is degraded at temperatures above 428.degree. F.
Hence, to preserve the quality of the hemicellulose product stream,
the hemicellulose exposure to temperatures above 356.degree. F.
should be as short as possible. The in-line reactor heater--static
mixer system raises the temperature of the hemicellulose to between
329.degree. F. and 347.degree. F. The time to bring the temperature
within this range is typically less than about 10 seconds to about
20 seconds.
[0047] Once heated, the hemicellulose is reacted with NaOH in the
reactor/static mixer. The static mixer accepts the hemicellulose, a
high viscosity stream and NaOH, the low viscosity stream. The NaOH
is injected into the high viscosity stream, mixed by static mixing
and a chemical reaction occurs between the alkali and the
hemicellulose. In particular, the NaOH hydrolyzes the
hemicellulose. The process of the present invention, unlike
conventional sugar extraction processes, does not rely upon
chemical reactions for extraction. Instead, the process of the
present invention utilizes both sophisticated mechanical
separation, occurring in the static mixer, coupled with NaOH
addition for hydrolysis, for extraction and formation of
hydrolysates.
[0048] The hydrolysates are separated, in some embodiments, by a
simulated moving bed adsorptive separation technology, hereinafter
referred to as a "SMB." The SMB is performed using chiral
stationary phases. Chiral stationary phases are described in U.S.
Pat. Nos. 5,254,258 and 5,290,440. The chiral stationary phases
separate stereoisomers of monomers such as L-arabinose from each
other. The SMB is usable to separate any stereolsomers. While an
SMB is described herein for stereoisomers, it is understood that
other types of separation technology may be more suitable for other
type of bioactive materials.
[0049] The SMB comprises an apparatus for performing a continuous
countercurrent moving bed high pressure liquid chromatographic
separation of a multicomponent feedstream which comprises a
plurality of serially interconnected adsorbent chambers with each
adsorbent chamber having an inlet and an outlet on opposite ends of
the chamber and adapted to contain a quantity of a selective
adsorbent; a feed stream header line; a desorbent stream header
line; a raffinate stream header line; an extract stream header
line; a set of valves for each adsorbent chamber, with each set of
valves comprising a first valve which controls the flow of a
raffinate stream from the apparatus; a second valve which controls
the flow of both the desorbent stream and the extract streams; a
third valve which controls the flow of the feed stream between the
feed stream header line and an specific adsorbent chamber; a fourth
valve which controls the flow of fluid circulating between the
interconnected adsorbent chambers; and, a feed valve flush line
which directly connecters a port on the third valve to a port on
the fourth valve.
[0050] One simulated moving bed is described in U.S. Pat. No.
6,004,518, which is incorporated herein by reference. One
embodiment of an SMB is illustrated generally in FIGS. 2A and 2B.
FIGS. 2A and 2B illustrate the transfer lines, adsorbent chambers
and valves employed in an apparatus containing six adsorbent
chambers. The lines between chambers "C" and "D" in the middle of
the apparatus are zigzagged to represent the other adsorbent
chambers, transfer lines and associated sets of valves that could
be present at this location in the apparatus to increase the number
of adsorbent chambers as desired. For purposes of presentation in
the limited confines of one sheet of drawing, the depiction of the
apparatus is limited to the six adsorbent chambers of FIGS. 2A and
2B. The nomenclature of components of the apparatus and the
reference characters for each is set out in Table 1.
1 TABLE 1 1 Mobile phase header 2 Feed header 3 Raffinate header 4
Extract header 5 (Extract) recycle header 6-10 Mobile phase feed
lines 11-15 Feed stream feed lines 16-20 Extract stream withdrawal
line 21-25 Raffinate stream withdrawal line 26-30 Recycle stream
withdrawal line 31-36 Chamber inlet line 37-42 Raffinate
valve-two-way 43-48 Mobile phase/extract valve--three way 49-54
Feed valve--three way 55-60 Recycle valve--three-way 61-66 Feed
valve flush line 67-72 Recycle valve outlet valve 73-78 Chamber
outlet line 79-84 Inlet line branch line
[0051] Referring to FIG. 2A, the hemicellulose hydrolysate stream
enters through feed header line 2. The feed header line "feeds"
into chamber F. Several feed lines 11-15 feed off of the header to
carry hemicellulose hydrolysate to adsorbent chambers A-F. The flow
of hydrolysate through line 2 is substantially continuous. However,
there is flow through only one of the feed stream lines 11-15 at
any point of time during the operation of the apparatus. This is
because feed is only passing into the entrance of one of the
adsorbent chambers at any point of time during a cycle of
operation. In a similar manner, a mobile phase stream, a desorbent
stream, is simultaneously charged to the apparatus via line 1. Line
1 also extends to the right-hand side of the apparatus with a
terminal portion of header line 1 acting as the mobile phase
delivery line to chamber F. Individual mobile phase feed lines 6-10
branch off of the mobile phase header line 1 and deliver the mobile
phase to one of the other individual adsorbent chambers A through
F. As with the feed stream, the mobile phase flows through the
header line are substantially continuous. However, the mobile phase
only flows through one of the feed lines 6-10 at any point of time
during the operation of the process.
[0052] The point at which the feed stream enters an adsorbent
chamber marks the beginning of the adsorption zone or Zone I. Zone
I continues to the point at which the remaining components of the
feed stream are withdrawn as the raffinate stream. The point at
which the mobile phase (desorbent) enters an adsorbent chamber
marks the beginning and upstream end of the desorption zone or Zone
III. Zone II is a purification zone between the point at which the
extract stream is removed and the feed stream is passed into the
apparatus. Zone IV separates the adsorption and desorption zone and
lies between the raffinate withdrawal point and the mobile phase
injection point.
[0053] As an example of this zone nomenclature, if the apparatus
comprises 16 adsorbent chambers, referred to as chambers A through
P, a feed stream may be charged to the inlet of adsorbent chamber H
and passed through 6 adsorbent chambers before being removed from
the apparatus at the outlet of adsorbent chamber C as the raffinate
stream withdrawn from the apparatus. The mobile stream and
desorbent stream are charged to the inlet of adsorbent chamber A
with the resultant extract stream removed from the outlet of
adsorbent chamber O, with this forming an extraction zone or Zone
III of the apparatus comprising 3 adsorbent beds. An external
recycle stream is withdrawn fro the outlet of adsorbent chamber B
located one chamber downstream from the point of removal of the
raffinate.
[0054] In FIG. 2, at some time, the feed stream from the header
line 2 flows downward through feed line 11 into the feed valve 49
associated with adsorbent chamber A. With the three-way feed valve
49 being in an open position, the feed stream emerges from the
valve and continue to flow through the terminal portion of line 11
to the junction with the chamber inlet line 36. Purging this
terminal portion is a key to the apparatus described. The feed
stream flows upward through line 36 to the inlet of adsorbent
chamber A which is at the top of the chamber. The feed stream
enters the adsorbent chamber A and the actual adsorptive separation
begins. The different components of the feed stream are retained at
different rates by the adsorbent with some components such as
solvent components being essentially unretarded. The components of
the feed stream are therefore separated such that the different
components have different concentration profiles in the stream
flowing through the adsorbent chamber. The partially fractionated
feed stream emerges fro the bottom of the adsorbent chamber A and
is carried by the chamber outlet line 73 to the inlet port of the
three-way recycle valve 60 of chamber F. This three-port valve
allows the withdrawal at specific points in time of a small
quantity of liquid referred to as external recycle. This liquid is
basically high-purity solvent or mobile phase material that is
trapped in a "dead bed" of the system during operation and that is
withdrawn for recovery and recycled. The optional external recycle
flow is therefore a pulse collected once during each change in the
position of the valves used in the apparatus. The external recycle
material is collected for reuse in the process if this is allowed
by the procedures which govern the operation of the system. The
recycle may be reusable as mobile phase material.
[0055] The fluid stream removed from adsorbent chamber A 10 through
line 73 passes through the recycle valve 60 into the recycle valve
outlet line 72 and is divided into two separate portions. The major
portion flows into the adsorbent chamber inlet line 31 and a
smaller port flows through the feed valve flush line 66. The
portion of the circulating liquid flowing through line 66 pushes
any residual feed stream material from the internal volume of the
feed valve 54 and from the small delivery section of feed line 2
between the feed valve 54 and from the small delivery section of
feed line 2 between the feed valve 54 and chamber inlet line 31.
Alternatively, a small portion of the fluid otherwise removed as
the external recycle may be allowed to flush valve 54 and feed line
31. The advantage of this is that the line between the valve and
chamber inlet line 31 are filled with mobile phase liquid and
neither extract profiles which had been partially developed in the
preceding adsorbent chamber. The material flowing through the feed
inlet valve for the purposes of flushing the valve and the feed
line is admixed with the rest of the material flowing through line
31 and continues to the inlet of the adsorbent chamber F.
[0056] Other valves in each set of valves for adsorbent chambers A
and F are in a closed position. Other fluids are not withdrawn or
passed into the apparatus through any valve in either set of
valves.
[0057] The feed valve associated with a particular adsorbent
chamber is always positioned to be open to receive flush fluid
except for a short period of time during which feed is flowing
through the valve. Thus, the valve and the delivery section of the
feed stream line contain fluid having the same composition as that
flowing past the junction of the feed stream line with the chamber
inlet line.
[0058] Two options exist for the operation of the feed valve after
sufficient fluid has been passed through it to completely flush the
feed line. First as set out above, the valve may be allowed to stay
in this position with fluid from line 73 continuing to flow through
both lines 66 and 31 until feed again enters through valve 54.
Alternatively, the valve may be moved to block the flow through
line 66 at some time before it is required to move the valve to
allow the feed stream to enter the apparatus.
[0059] As the process stream continues to flow through adsorbent
chamber F, the compounds are further separated to produce a more
defined set of concentration profiles in the flowing liquid. The
effluent of the adsorbent chamber F is removed in the chamber
outlet line 74 and passed into the recycle valve 59. The recycle
valve 59 is open and allows all the fluid to travel into outlet
line 71. One portion of the fluid then flows into the chamber inlet
line 32 and passes upward in the figure. A second portion flows
through line 65 and valve 53, which directs into the terminal
delivery section of line 15. The two portions then rejoin and flow
through line 32. Prior to reaching the inlet of chamber E, the
fluid is removed through the raffinate withdrawal line 24. The
fluid being removed in this manner basically comprises the less
readily retained components of the feed stream and any associated
solvent components. The raffinate stream passes through the open
two-port raffinate valve 41 and continues through the raffinate
stream withdrawal line 24 to the junction with the raffinate header
line 3. The raffinate stream is then removed from the right-hand
end of the Figure through header line 3. At this point in time, two
of the four valves in this set of valves associated with adsorbent
chamber E, that is, valves 47 and 53, are in a closed position and
there is no flow through these valves other than flush liquid in
valve 53. Adsorbent chambers A and F therefore form adsorption Zone
I.
[0060] Each adsorbent chamber has a chamber inlet line 31-36 and a
chamber outlet line 73-78. Also associated with each chamber is a
set of four valves comprising three-way valves and one two-way
valve. The three-way valve allows a central or common conduit to be
selectively connected to either of the remaining ports The two-way
valves are raffinate valves 37 through 42. The three-way valves
include the mobile phase/extract valves 43-48, the feed valves
49-54 and the recycle valves 55-60.
[0061] Feed valves are illustrated in FIGS. 3A and 3B. The feed
stream is brought to the valve in line 11 and flows through the
valve only when it is in an open position. In one embodiment, this
is the only flow through the valve. The outlet line is stagnant
when there is no flow of feed through this valve.
[0062] The flow rates of the feed stream, desorbent stream and
extract stream are all regulated on the basis of set flow rates,
which are held constant. The raffinate stream rate is on pressure
control. A flow rate control valve, not shown, regulates the
effluent rate of the extract stream of header line 4 to be less
than the feed rate of the desorbent stream of header line 1. The
outlet rate of the raffinate stream is set by a pressure control
valve also not shown. The rate of flow of the raffinate is
therefore automatically equal to the two input streams minus the
extract stream.
[0063] At this time, a portion of the extract material flowing
through the chamber inlet line equal to the difference between the
desorbent and extract stream flow rates is charged to the inlet of
the purification zone, Zone II, and is referred to as Zone II
material. The function of liquid flowing through this zone is to
remove raffinate material from the nonselective pore volume of the
adsorbent and chambers of the purification zone. This material
flows through any interconnecting lines leading into the inlet of
the next adsorbent chamber. The liquid may flow through two or more
adsorbent chambers. It then joins the feed material and flows into
the inlet of the first chamber of the adsorption Zone, Zone I. The
raffinate material flushed from the purification zone therefore
flows into the adsorption zone. The raffinate components in the
material being flushed into the adsorption zone in this manner
merely travel through the adsorption zone and do not interfere with
the adsorption of the desired component from the feed stream.
[0064] The adsorbent particles may be in the form of any shape,
sphere or monolith, and of any size suitable for use in high
pressure liquid chromatography. The composition of the adsorbent is
not a controlling factor, but, for some embodiments, can be
controlling. All of the chambers contain the same adsorbent which
may be a commercially available adsorbent.
[0065] Operating conditions include a temperature of about 20 to
100 degrees Centigrade. Pressure ranges form 700 to 25,000 kPa.
Flow rates are effective to produce dry product of about 1000
kg/day.
[0066] The mobile phase or desorbent may be any compound or mixture
of compounds which is given the desired phase at the chosen
operating conditions, does not react with either the adsorbent or
the compounds being separated and is tolerable or totally separable
from the intended products. The desorbent contains a chiral
moiety.
[0067] With the process of the present invention, the hydrolysate
mixture may be separated on the basis of monomer, oligomer, and
polymer in a single step and then separated on the basis of
stereoisomer, i.e. optical or chirally pure monomer separation, in
a second step. In another embodiment, the hydrolysate mixture may
be separated and a desired stereoisomer may be extracted in a
single step.
[0068] In one particular embodiment of the process of the present
invention, L-arabinose is extracted from biomass, the source of
which is sugar beet pulp. The sugar beet pulp is transported from a
sugar beet process stream to a chopper or grinder and then to a
hopper. From the hopper, the chopped or ground beet pulp is
transported to a retention tube by a conveyor such as a feed screw.
Within the retention tube, the sugar beet pulp is formed into a
solid plug.
[0069] The solid plug is transferred to the steam pressurized
reactor where it is disintegrated by defibrination. The reaction
temperature is 160 to 230 degrees Centigrade and the time period is
about 2 to 10 minutes. Upon disintegration, the biomass is
substantially instantaneously depressurized by removal from the
reaction. This process separates the cellulose, lignin and
hemicellulose from each other. The hemicellulose is separated and
is passed through the heater--reactor/static mixer system described
above. Arabinose is one of the sugar hydrolysates produced.
[0070] In one embodiment of the process of the present invention,
sugar products obtained by SMB are crystallized. In one embodiment,
the crystallization is performed using a low intensity ultrasonic
agitation. It is believed that this crystallization produces a
product wherein crystals have few inclusions, are uniform in shape,
in size, in density and in purity.
[0071] In one embodiment, the L-arabinose is separated from other
monomers using SMB methods described herein. In another embodiment,
the L-arabinose is separated from a mixture of hemicellulose
hydrolysates.
[0072] The Example described herein is presented to describe an
extraction process of the present invention and is not intended to
limit the scope of the present invention. A mass balance of the
process is illustrated schematically in FIG. 4. The biomass
extracted in FIG. 4 is sweet beet pulp, SBP. The mass balance is
based upon a weight of SBP of 100 obs. The SBP is subjected to a
steam explosion as described herein at a temperature within a range
of 140 to 190 degrees Centigrade. At a steam explosion temperature
of 160 degrees Centigrade, two fractions are formed in the process.
The fractions include a water soluble fraction of 30 lbs., that
includes pectin and hydrocarbons and a water insoluble fraction of
70 lbs. that includes cellulose, protein, and lignin. This is a
gross fractionation. The remaining processing is biorefining.
[0073] The soluble fraction is mixed with isopropyl alcohol and is
treated in a static mixer, such as a Komax mixer to form two
fractions. One fraction, a water insoluble fraction of 19 lbs.,
includes pectin and arabinogalactan. Another fraction, a water
soluble fraction of 11 lbs., includes arabinogalactan. The
insoluble fraction is further treated in the static mixer to form
three fractions of low molecular weight, medium molecular weight
and high molecular weight, respectively. The medium molecular
weight fraction is further treated in the static mixer and is
subjected to hydrolysis to form L-arabinose, galacturonic acid and
xylose.
[0074] The soluble arabinogalactan fraction of 11 lbs, is treated
with NaOH in a static mixer to make an insoluble hydrocarbon. The
insoluble hydrocarbon is subjected to acid hydrolysis in a mixer
such as a Komax PFR to make the following fractions: oxalic acid,
galactose, mannose and L-fucose. The oxalic acid is treated to form
araban, a pentamer of L-arabinose. The araban is subjected to acid
hydrolysis to form L-arabinose. The mannose is treated to form
mannitol.
[0075] The 70 lb, insoluble fraction of cellulose, protein, and
lignin is treated in a static mixer with KOH to form two fractions:
a 50 lb. water insoluble cellulose fraction and a 20 lb. water
soluble protein/lignin fraction. The cellulose fraction may be
treated with acetic anhydride to form cellulose acetate. The
cellulose may be treated with sulfuric acid in a mixer such as a
Komax PFR to form levoglucosnone, then levulinic acid and then up
to 13 extraction products. The cellulose may also be treated in a
Komax PFR with chloroacetic acid to form carboxymethyl cellulose,
cmc, in monomer form of 2.7 DOS, oligomer form of 1.5 DOS, and
polymer form of 1.0 DOS.
[0076] The 20 lb. protein/lignin fraction is subjected to a flip pH
in a Komax mixer to form a soluble 10 lb. protein fraction and a 10
lb. insoluble lignin fraction. The protein fracton is treated in a
Komax mixer to from protein isolates. The lignin is treated in a
Komax pfr to form coniferyl alcohol.
[0077] One oligomer formed in the treatment of cellulose is
sucrose. In one embodiment, the sucrose is treated in a Komax PFR
to form an epoxy precursor.
[0078] In one embodiment, a portion of the SBP is treated to form
methane, which is used to provide a source of energy for operating
the pumps and mixers in the process.
[0079] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, limited only by the appended claims
rather than by the foregoing description. All changes which come
within the meaning and range of functional equivalency of the
claims are to be embraced within their scope.
* * * * *