U.S. patent application number 13/025088 was filed with the patent office on 2011-08-11 for production of biodiesel, cellulosic sugars, and peptides from the simultaneous esterification and alcoholysis/hydrolysis of materials with oil-containing substituents including phospholipids and cellulosic and peptidic content.
This patent application is currently assigned to Inventure Chemical, Inc.. Invention is credited to William Wes Berry, Stephen L. Hillis, Mark G. Tegen.
Application Number | 20110195471 13/025088 |
Document ID | / |
Family ID | 39795086 |
Filed Date | 2011-08-11 |
United States Patent
Application |
20110195471 |
Kind Code |
A1 |
Berry; William Wes ; et
al. |
August 11, 2011 |
PRODUCTION OF BIODIESEL, CELLULOSIC SUGARS, AND PEPTIDES FROM THE
SIMULTANEOUS ESTERIFICATION AND ALCOHOLYSIS/HYDROLYSIS OF MATERIALS
WITH OIL-CONTAINING SUBSTITUENTS INCLUDING PHOSPHOLIPIDS AND
CELLULOSIC AND PEPTIDIC CONTENT
Abstract
The present invention relates to a method for producing fatty
acid alkyl esters as well as cellulosic simplified sugars,
shortened protein polymers, amino acids, or combination thereof
resulting from the simultaneous esterification and hydrolysis,
alcoholysis, or both of algae and other oil containing materials
containing free fatty acids (FFA), glycerides, or combination
thereof as well as polysaccharides, cellulose, hemicellulose,
lignocellulose, protein polymers, or combination thereof in
presences of an alcohol and an acid catalyst.
Inventors: |
Berry; William Wes;
(Lakeland, FL) ; Tegen; Mark G.; (Gig Harbor,
WA) ; Hillis; Stephen L.; (Lakeland, FL) |
Assignee: |
Inventure Chemical, Inc.
Gig Harbor
WA
|
Family ID: |
39795086 |
Appl. No.: |
13/025088 |
Filed: |
February 10, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12061038 |
Apr 2, 2008 |
|
|
|
13025088 |
|
|
|
|
60921327 |
Apr 2, 2007 |
|
|
|
Current U.S.
Class: |
435/165 ;
554/167; 554/170; 554/8 |
Current CPC
Class: |
C07C 67/03 20130101;
Y02E 50/10 20130101; Y02E 50/16 20130101; C12P 7/10 20130101; Y02W
30/74 20150501; C11B 13/02 20130101; Y02E 50/13 20130101; Y02E
50/17 20130101; C11C 3/003 20130101; C07C 67/08 20130101; C07C
67/03 20130101; C07C 69/24 20130101; C07C 67/03 20130101; C07C
69/52 20130101; C07C 67/08 20130101; C07C 69/52 20130101; C07C
67/08 20130101; C07C 69/24 20130101 |
Class at
Publication: |
435/165 ;
554/170; 554/167; 554/8 |
International
Class: |
C12P 7/10 20060101
C12P007/10; C11C 3/00 20060101 C11C003/00; C11C 3/04 20060101
C11C003/04; C11B 1/00 20060101 C11B001/00 |
Claims
1. A method for making fatty acid alkyl esters, the method
comprising: (a) combining a feedstock with an alcohol and an acid
catalyst, wherein the feedstock comprises (i) free fatty acids
(FFAs), glycerides, or both and (ii) cellulosic material, proteins,
or both; and (b) reacting the feedstock and the alcohol, at a
temperature in the range of 140.degree. C. to 300.degree. C., and
at a pressure that is sufficient to prevent boiling of the alcohol
during the reaction to (i) generate fatty acid alkyl esters, (ii)
cleave the cellulosic material, if present, and (iii) shorten the
proteins, if proteins are present.
2. The method of claim 1, wherein the feedstock contains at least
10 wt % cellulosic material based on the dry weight of the
feedstock.
3. The method of claim 1, wherein the feedstock contains at least
10 wt % proteins based on the dry weight of the feedstock.
4. The method of claim 1, wherein the water content of the
combination before reaction is at least 3 wt % of the dry weight of
the feedstock.
5. The method of claim 1, further comprising adding a fatty acid
alkyl ester to the combination before reacting.
6. The method of claim 1, further comprising drying the feedstock
prior to combining the feedstock with the alcohol and acid
catalyst.
7. The method of claim 6, wherein the water content of the
feedstock after drying is in the range of about 3 wt % to about 5
wt % of the dry weight of the feedstock.
8. The method according to claim 1, wherein said feedstock is
algae, dried distillers grain (DDG), or a mixture thereof.
9. The method of claim 1, wherein the alcohol is methanol or
ethanol.
10. The method of claim 1, wherein the alcohol is in an amount from
50% to 320% molar excess of the contained oil in the feedstock.
11. The method according to claim 1, wherein the acid catalyst is
sulfuric acid.
12. The method of claim 1, wherein the acid catalyst is in an
amount from 4 wt % to 8 wt % of the dry weight of the
feedstock.
13. The method of claim 1, wherein the temperature is in the range
of 175.degree. C. to 275.degree. C.
14. The method of claim 1, wherein the pressure is at least 20 psig
above the vapor pressure of the alcohol at the temperature of the
reaction.
15. A method for making fatty acid alkyl esters, the method
comprising: (a) combining a feedstock with an alcohol and an acid
catalyst, wherein the feedstock comprises free fatty acids,
glycerides, at least 10 wt % cellulosic material based on the dry
weight of the feedstock, and at least 10 wt % proteins based on the
dry weight of the feedstock; and (b) reacting the feedstock and the
alcohol, at a temperature in the range of 140.degree. C. to
260.degree. C., and at a pressure that is sufficient to prevent
boiling of the alcohol during the reaction to generate fatty acid
alkyl esters, cleave the cellulosic material, shorten the
proteins.
16. The method of claim 15, wherein the water content of the
combination before reaction is at least 3 wt % of the dry weight of
the feedstock.
17. The method of claim 15, further comprising adding a fatty acid
alkyl ester to the combination before reacting.
18. The method of claim 15, further comprising separating the
resulting fatty acid alkyl esters from the resulting cleaved
cellulosic material.
19. The method of claim 18, further comprising fermenting the
cleaved cellulosic material to produce ethanol.
20. The method of claim 15, wherein the algal lipids are converted
into free fatty acids using an acid catalyzed reaction at less than
140.degree. C.
21. The method according to claim 15 wherein the pressure is less
than 50 psi.
22. The method of claim 15, wherein the acid catalyzed hydrolysis
step breaks down algae cell walls and releases the algal
lipids.
23. The method of claim 22, further comprising adding methanol to
the fatty acids to form fatty acid methyl esters (FAME).
24. The method of claim 23, wherein the alcohol is in an amount
from 50% to 320% molar excess of the contained oil in the
feedstock.
25. The method of claim 15, further comprising centrifuging,
filtering or settling the suspension to form liquid and solid
components.
26. The method of claim 25, further comprising decanting the liquid
component by a phase separation procedure to form a heavy phase and
a light phase.
27. The method of claim 26, wherein the heavy phase comprises
water, glycerol, acid and methanol.
28. The method of claim 25, wherein the light phase comprises FAME
and free fatty acids (FFA).
29. The method of claim 26, wherein the heavy phase is preheated by
flashing to separate glycerol and acid from water and methanol.
30. The method of claim 26, further comprising removing the
glycerol and acid in a liquid bottoms stream.
31. The method of claim 27, wherein the water and methanol are
distilled to separate the methanol from the water.
32. The method of claim 27, further comprising recycling the
distilled methanol to react with free fatty acids.
33. The method of claim 28, wherein the FFA and FAME are reacted
with additional acid and methanol to complete the production of
FAME from FFA.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present patent application is a continuation of U.S.
application Ser. No. 12/061,038 filed Apr. 2, 2008, which claims
the benefit of U.S. provisional patent application Ser. No.
60/921,327 filed on Apr. 2, 2007. The contents of these prior
applications are hereby incorporated by reference and in their
entirety.
FIELD OF THE INVENTION
[0002] The present invention pertains to the esterification of free
fatty acids (FFAs) and glycerides with alcohol in the presence of
an acid catalyst to form fatty acid alkyl esters. The present
invention further pertains to the simultaneous esterification and
hydrolysis/alcoholysis of a feedstock containing free fatty acids
(FFAs), glycerides, or both as well as cellulosic material,
proteins, or both in the presence of an alcohol and acid catalyst
to form fatty acid alkyl esters as well as cleaved cellulosic
material, shorter peptides, amino acids, or combination
thereof.
BACKGROUND OF THE INVENTION
[0003] Over the past three decades interest in the reduction of air
pollution, and in the development of domestic energy sources, has
triggered research in many countries on the development of
non-petroleum fuels for internal combustion engines. For
compression ignition (diesel) engines, it has been shown that the
simple alcohol esters of fatty acids (biodiesel) are acceptable
alternative diesel fuels. Biodiesel has a higher oxygen content
than petroleum diesel, and therefore reduces emissions of
particulate matter, hydrocarbons, and carbon monoxide, while also
reducing sulfur emissions due to a low sulfur content.
[0004] For spark ignition (gasoline) engines, ethanol, produced by
fermentation of simple sugars generated from corn starch, can be
blended with petroleum gasoline to substitute petroleum content
with renewable content fuel, reduce dependence on foreign oil,
reduce carbon dioxide emissions, and improve octane in the blended
fuel. Since both ethanol and biodiesel are made from agricultural
materials, which are produced via photosynthetic carbon fixation
(e.g., by plants and by animals that consume plants), the
combustion of biodiesel and ethanol does not contribute to net
atmospheric carbon levels.
[0005] Initial efforts at the production, testing, and use of
biodiesel employed refined edible vegetable oils (e.g. soybean oil,
canola oil), used cooking oils (e.g. spent fryer oils) and animal
fats (e.g., beef tallow) as feedstocks for fuel synthesis
(Krawczyk, T., INFORM, 7: 800-815 (1996); Peterson, C. L., et al.,
Applied Engineering in Agriculture, 13: 71-79 (1997); Holmberg, W.
C., and J. E. Peeples, Biodiesel: A Technology, Performance, and
Regulatory Overview, National Soy Diesel Development Board,
Jefferson City, Mo. (1994)).
[0006] Simple alkali-catalyzed transesterification technology
(Freedman, B., et al., J. Am. Oil Chem. Soc., 61(10): 1638-1643
(1984)) is efficient at esterifying the acylglycerol-linked fatty
acids of such feedstocks and is employed in making these fuels.
More recently, methods have been developed to produce fatty acid
methyl esters (FAME) from cheaper, less highly refined lipid
feedstocks such as spent restaurant grease (Mittelbach, M., and P.
Tritthart, J. Am. Oil Chem. Soc., 65(7):1185-1187 (1988); Graboski,
M. S., et al., The Effect of Biodiesel Composition on Engine
Emissions from a DDC Series 60 Diesel Engine, Final Report to
USDOE/National Renewable Energy Laboratory, Contract No.
ACG-8-17106-02 (2000); Haas, M. J., et al., Enzymatic Approaches to
the Production of Biodiesel Fuels, in Kuo, T. M. and Gardner, H. W.
(Eds.), Lipid Biotechnology, Marcel Dekker, Inc., New York, (2002),
pp. 587-598).
[0007] In addition to acylglycerols, less highly refined lipid
feedstocks can contain substantial levels of free fatty acids (FFA)
and other nonglyceride materials. Biodiesel synthesis from these
feedstocks can be accomplished by conventional alkaline catalysis,
which then requires an excess of alkali since the FFA (which are
not esterified by this method) are converted to their alkali salts.
These alkali salts can cause difficulties during product washing
due to their ready action as emulsifiers. Ultimately, the alkali
salts are removed and discarded. This approach thus involves a loss
of potential product, increases catalyst expenses, and can entail a
disposal cost.
[0008] Further, with higher FFA levels, i.e. typically in excess of
2%, a general approach is to utilize an acid esterification step,
since at higher FFA values the extent of soap formation with a
single stage, transesterification process is excessive and renders
the process uneconomical and potentially unworkable. To handle the
higher FFA content, a two step process involving first
acid-catalyzed esterification of the free fatty acids and then
alkali-catalyzed transesterification of glyceride-linked fatty
acids can be employed to achieve conversion of mixed, heterogeneous
feedstocks (Canakci, M., and J. Van Gerpen, Biodiesel Production
from Oils and Fats with High Free Fatty Acids, Abstracts of the
92.sup.nd American Oil Chemists' Society Annual Meeting & Expo,
p. S74 (2001); U.S. Pat. Nos. 2,383,601; 2,494,366; 4,695,411;
4,698,186; 4,164,506). However, these methods can require multiple
acid-catalyzed esterification steps to reduce the concentration of
free fatty acids to acceptably low levels. In addition, high
separation efficiency is required between the two stages to
minimize the potential for acid catalyst transfer into the base
catalyst section.
[0009] The feedstocks used for current biodiesel production are
conventional commodity materials, thus they have other established
markets which basically set the minimum commodity prices. As a
result, the bulk of the biodiesel production cost relates to the
feedstock cost. While there are a number of established process
technologies in the biodiesel industry, as a result of the
feedstock cost being such a high factor (i.e. 75% to 80%) there is
a surprisingly small difference between the various processes in
overall operational costs (due to this feedstock factor).
[0010] The production of ethanol for fuel use is well established
and the growth in this industry over the past 2 decades has been
significant. Fermentation is an (obviously) old process going back
literally thousands of years to early wine and beer making. The
basic techniques remain the same, however in the modern ethanol
production process highly efficient enzymes and yeasts have been
developed to provide for more efficient conversion of the
fermentable materials. Further, the process technology associated
with fuel grade ethanol production has also advanced over the
years, e.g. energy recovery, so that current technology has a high
degree of efficiency.
[0011] The primary feedstocks for current commercial ethanol
production are corn (primarily in the United States) and sugar
(especially in Brazil). As in the biodiesel case, these materials
are "conventional" agricultural commodities and have historically
had various markets associated with them, i.e. food sources and the
like. It is also apparent that since these are commodity products,
there are various non-fuel market pressures that dictate price. As
such, for ethanol production, as in the case of biodiesel, the
feedstock represents the vast majority of the operating cost (i.e.
as much as 80%).
[0012] For both the biodiesel and ethanol fuel markets and for the
large-scale expansion of the renewable fuels industries, it is
apparent that development of a potentially large scale, lower cost
feedstock source would be advantageous. Recently, significant
advances have been made in carbon dioxide sequestering technology
(aquatic species program reference, NREL, GFT, a U.S. company)
using various species of algae to provide photosynthetic carbon
fixation. This technology has tremendous value when applied to
industrial sources of carbon dioxide such as; coal fired power
generation, natural gas fired power generation, petroleum fired
power generation, industrial gas generation, cement manufacturing,
industrial fermentation, as well as various additional industries
that are significant emitters of carbon dioxide. The algae
resulting from the photosynthetic carbon fixation represents an
opportunity for the production of transportation fuels as well as
various value added chemical products. The volume of algae produced
per acre, in a designed pond or "farming" system, is estimated at
between 200,000 pounds to 600,000 pounds per year of algae on a dry
basis; and is substantially greater, in terms of oil content and
fermentable material content, than the volume of soybeans or corn
produced per acre at 2,500 pounds to 10,000 lbs per year. The
volume of algae produced using the above method allows for a far
greater production density versus corn or soybeans with a
relatively small geographic footprint. In addition, the algae
selected comprise free fatty acids (FFA), triglycerides,
polysaccharides, cellulose, hemicellulose and/or lignocellulose.
However, the economical processing of the selected algae provides
significant challenges for conventional biofuel processing
techniques.
[0013] For the algae scenario, a significant degree of pretreatment
of the sludge is required to prepare the material for the more
traditional solvent extraction methods to recover the contained
oil. This front-end pretreatment would then need to be combined
with multi-stage esterification, (for free fatty acid
esterification) and transesterification (for triglyceride
conversion), and a completely separate process would be required
for acid hydrolysis of the lipid depleted algae pulp to produce
monosaccharides, disaccharides, trisaccharides or polysaccharides
for production of ethanol by fermentation. This series of
processing steps would add significant cost to the resulting
materials to be produced from algae. Therefore, there is a need for
further development of simplified processing routes for the
production of fatty acid alkyl esters (i.e. FAME), monosaccharides,
disaccharides, trisaccharides or polysaccharides in a simplified,
direct process.
[0014] In addition, the current growth in biofuel production from
food commodities is generating a substantial increase in
co-products such as corn distillers grains, sorghum distillers
grains, and rice bran meal. These co-products have underutilized
value from the cellulosic content (45-55% by mass) and oil content
(7-22% by mass) which represent an opportunity to increase the
supply of biofuels to market by simply increasing the processing
efficiency of current methods.
[0015] Again, the interest in cellulosic feeds for ethanol has
increased considerably over the past several years, however some of
the same issues apply to this source as to feeds such as algae. For
example, with cellulosic feeds the typical approaches include
enzyme treatment followed by yeasts which convert the cellulosic
materials to sugars and subsequent alcohol, but has little effect
on any contained oil content. For example distillers grains have
both cellulosic content as well as contained oil values, both of
which could be useful for conversion to biofuels.
[0016] Thus, there remains a significant need in the art to develop
a simple and efficient method for the production of biofuels and
ethanol from renewable energy sources.
SUMMARY OF THE INVENTION
[0017] The present invention relates to a method for making fatty
acid alkyl esters by (a) combining a feedstock with an alcohol and
an acid catalyst and (b) reacting the combination at a pH in the
range of 0 to 5, at a temperature in the range of 140.degree. C. to
260.degree. C., and at a pressure that is sufficient to prevent
boiling of the alcohol during the reaction, wherein the feedstock
comprises (a) free fatty acids (FFAs), glycerides, or both and (b)
cellulosic material, proteins, or both and wherein the reaction
products comprise (a) fatty acid alkyl esters and (b) cleaved
cellulosic material, shortened proteins, amino acids, or a
combination thereof.
[0018] The following reactions can occur in the above method: (a)
the direct esterification of FFAs into fatty acid alkyl esters, (b)
the transesterification of glycerides into fatty acid alkyl esters,
(c) the hydrolysis, alcoholysis, or both of the cellulosic material
into cleaved cellulosic material, and (d) the hydrolysis,
alcoholysis, or both of protein into shorter peptides, amino acids,
or both.
[0019] The present invention is further directed to the product
from the reaction of the feedstock with the alcohol and acid
catalyst.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 provides a schematic of the reaction of the feedstock
(110) with the alcohol (120) in the presence of the acid catalyst
(130) and optionally in the presence of water (160) and fatty acid
alkyl esters (170) in a pressurized reactor (140) to products
(150).
[0021] FIG. 2 shows the detailed process concept used for the
simultaneous production of biodiesel and ethanol from the algae
and/or feedstocks, such as agricultural by-product material. The
overall approach is shown for multiple feedstocks. If dry material
is received, then the front end drying system would not necessarily
be required.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention relates to a method for producing
fatty acid alkyl esters as well as cellulosic simple sugars,
shortened protein peptide polymers, and amino acids involving
esterifying and performing hydrolysis, alcoholysis, or both on a
material containing free fatty acids, glycerides, or both as well
as polysaccharides, cellulose, hemicellulose, lignocellulose,
protein, or combination thereof with an alcohol and an acid
catalyst.
[0023] Prior to the present invention, the conversion of biomass
into biofuel and ethanol was a time-consuming and multi-step
procedure that was both economically inefficient and wasteful.
Additionally, conventional methods are inhibited by the presence of
water. In contrast, a fast, single-step, and efficient method for
the conversion of biomass into biofuel and sugars to produce
ethanol can be performed in the presence of water. FIG. 1
illustrates a method of the present invention in which feedstock
(110) is reacted with alcohol (120) in the presence of an acid
catalyst (130) and optionally in the presence of water (160) and
fatty acid alkyl esters (170) in a pressurized reactor to yield
products (150).
[0024] The feedstock for this process can be, for example, algae
(e.g., fresh or salt water algae, prokaryotic algae), dried
distillers grains (DDG) from, e.g., corn or sorghum, rice bran,
jatropha seed, palm seed, vegetable oil seeds (e.g., soybean,
canola), eukaryota, protozoa, phytoplankton, cyanobacteria,
bacteria, corn ethanol fermentation residuals, or other
oil-containing material that may also contain potentially
fermentable cellulosic material (e.g., polysaccharides, cellulose,
hemicellulose, and lignocellulose), protein, or both. The oils of
the feed stock can include FFAs, monoglycerides, diglycerides,
triglycerides, or combination thereof. The feedstock can also be a
combination of different oil-containing materials.
[0025] The feedstock can contain from about 0 wt % to about 100 wt
% FFA, e.g., from about 5 wt % to about 10 wt % FFA. The feedstock
can contain about 0 wt % to about 100 wt % glycerides, e.g., from
about 10 wt % to about 50 wt % glycerides. The feedstock can
contain from about 0 wt % to about 50 wt % cellulosic material
(preferable less than about 30 or 40 wt %, but at least about 1, 5,
10, or 15 wt %). The feedstock can contain from about 0 wt % to
about 50 wt % protein (preferable less than about 30 wt %, but at
least about 1, 5, 10, or 15 wt %). Each of the amounts for the
feedstock components listed above is based on the dry weight of the
feedstock.
[0026] The feedstock can be unextracted meaning that it has not
been purified to remove certain components (e.g., water, cellulosic
material, proteins, or mixtures thereof). For example, the
feedstock can contain FFAs, glycerides, at least about 10 wt %
cellulosic material, and at least about 10 wt % proteins, wherein
both weight percentages are based on the total dry weight of the
feedstock. The feedstock can also be purified (e.g., a soapstock or
crude vegetable oil). The feedstock can contain husks, shells, or
other materials that are grown by the feedstock source other than
the feedstock. Materials that contain both oil and cellulosic
components lead to attractive renewable fuel alternatives. The
feedstock, prior to reaction, can be dried as, e.g., discussed
below. The feedstock can be ground to reduce its particle size
prior to reaction.
[0027] For purposes of this description, algae is used as the
feedstock, however those skilled in the art would understand that
other feedstock can be used. Also, the overall process is, as
indicated, applicable to the other feedstocks with adjustments to
the process configuration, e.g. if a dry distillers grain or dry
rice bran is used as a feedstock, then the drying step would not be
required.
[0028] In addition, with other feedstocks, there may be some
variations in the acid esterification chemistry such that alternate
co-products are formed in the reaction. For example, with a high
cellulosic feed (e.g., at least about 1, 5, 10, or 15 wt % but less
than about 30, 40, or 50 wt % based on the dry weight of the
feedstock) there may be further conversion of that component to
derivatized sugar compounds such as methyl or ethyl glucosides. For
example, when a solution of glucose in methyl alcohol is saturated
with hydrochloric acid a crystallizable compound having the formula
C.sub.6H.sub.11O.sub.6CH.sub.3, is formed.
[0029] A similar reaction takes place with all of the alcohols
which are capable of dissolving glucose, such as methanol, ethanol,
propanol, butanol, and their isomers, and the compounds formed
correspond to natural glucosides. The sugar entering into the
reaction need not necessarily be glucose, so that a number of such
artificial alcohol-derivatized sugars can be prepared. The
hydrochloric acid of the reaction to produce derivatized sugars can
also be replaced by another acid such as H.sub.5SO.sub.4. These
derivatized sugars, when boiled with dilute acid, react with water
and are decomposed into the sugar and alcohol. In addition, further
derivatization at the higher ranges of temperatures and pressures
can lead to valuable dehydration products from the sugars such as
5-(hydroxymethyl)furfural, levulinic acid, formic acid, and esters
thereof. The categorization of each feedstock may be necessary to
determine the best process splits and optimal end-products.
[0030] The alcohol for the invention can be, for example, methanol,
ethanol, propanol, butanol, isopropyl alcohol, sec-butanol,
t-butanol, benzyl alcohol or combination thereof. From a practical
standpoint, and for general fuel and potential downstream chemical
considerations, alcohols containing from 1 to 5 carbons would be
preferred, however, there may be specific situations and conditions
wherein higher alcohols could be used. Testing with a specific
alcohol would readily determine the amenability of a particular
alcohol. Again, for purposes of this discussion, methanol is used
as the alcohol, however those skilled in the art would understand
that other alcohols can be used. For example, in a combined system
that produces both ethanol and biodiesel, it is potentially
attractive to use some of the produced ethanol as the alcohol
reactant.
[0031] The acid catalyst for the invention can be, for example, an
inorganic acid (e.g., sulfuric acid, anhydrous hydrochloric acid,
anhydrous nitric acid, boron trifloride, and phosphoric acid), an
organic acid (e.g. organic sulfonic acid), a solid phase catalyst
(e.g., Envirocat.TM. EPZG, natural kaolinite clay,
B.sub.2O.sub.3/ZrO.sub.2, sulfated SnO.sub.2, and zeolites), or
combination thereof.
[0032] For the purposes of this description, sulfuric acid is used
as the acid catalyst, however those skilled in the art would
understand that other acid catalysts can be used.
[0033] In the process (see FIG. 2), the algae sludge (1), produced
via various algae growing processes, e.g. the recovery of CO.sub.2
from a power plant or other major CO.sub.2 producing stack gases,
or other feedstock is first dried in a flash drying system wherein
a recycled stream of superheated steam is used to dry the
feedstock. The water content of the feedstock after drying can be
about 0 wt % to about 10 wt % of the dry weight of the feedstock,
from about 3 wt % to about 10 wt % of the dry weight of the
feedstock, or from about 3 wt % to about 5 wt % dry weight of the
feedstock. The resulting steam, from the wet material, is purged
from the system (2) and used for downstream process heat.
[0034] Systems that are useful for this step include spin flash
dryers; spray dryers; loop dryers; and the like. The main criterion
for dryer choice is that the system can be operated at elevated
pressure to allow for production of reasonably usable purge steam.
A pressure of 10 psig to 30 psig is preferred with 15 psig to 20
psig most preferred. Drying can be carried out at atmospheric
pressure, however, in this case the resulting vapor from the dryer
cannot be reused for downstream steam uses. Pressurized drying
enhances the overall economics of the process, but is not essential
for practice of the technique, i.e. atmospheric drying is
acceptable, recognizing the economics of the system.
[0035] The dried algae (3) or other feedstock can be ground to
reduce its particle size and is then transferred to the Direct
Esterification Reactor system wherein the feedstock is mixed with
the selected alcohol (e.g., methanol) (5), and acid catalyst (4).
The amount of alcohol can vary, but would typically be sufficient
to allow for a slurry mixture. This typically provides sufficient
excess of alcohol for the reaction noting that 3 moles of alcohol
are required for reaction with 1 mole of triglycerides to form 3
moles of fatty acid alkyl esters and 1 mole of alcohol is required
for reaction with 1 mole of FFAs to form 1 mole of fatty acid alkyl
esters. As a minimum, the amount of alcohol should be in about a
15% molar excess of the contained oil. Preferably, the alcohol
should be in an amount from about 50 mol % to about 600 mol % of
the contained oil (i.e., glycerides and FFAs), preferably from
about 50 mol % to about 320 mol % of the contained oil and most
preferably from about 200 mol % to about 300 mol % of the contained
oil. On a weight percentage basis, the contained oil will require
about 11% to 12% by weight of methanol to form the methyl ester.
Higher alcohols would require a higher weight percentage of
alcohol. For practical operation, the amount of alcohol would
normally be in the range of about 50 wt % to 300 wt % of the dry
feedstock and preferably in the range of about 100 wt % to about
200 wt % of the dry feedstock.
[0036] To reduce the amount of alcohol used, and subsequently
reduce the downstream demethylation requirements, a portion of the
produced biodiesel (8A) can be recycled to the reactor to provide
liquid for slurry formation. The amount of fatty acid alkyl ester
(i.e., biodiesel) added to the reaction can be in an amount from
about 50 wt % to about 300 wt %, preferably from about 100 wt % to
about 200 wt %, and most preferably from about 125 wt % to about
150 wt % of the dry weight of the feedstock.
[0037] This will allow for introduction of alcohol in amounts
sufficient to provide the amount required for the reaction, plus
some excess to ensure complete reaction. In this case, the amount
of make-up alcohol (e.g. methanol) could be in the range of 5% to
15% by weight of the dry input feedstock.
[0038] The amount of acid catalyst can range from about 0% to about
15% by weight of the dry feedstock, preferably from about 3% to
about 9% by weight of the dry feedstock, and most preferably from
about 4% to about 8% by weight of the dry feedstock. The final
amount of acid will depend on the composition of the feedstock,
since there may be acid consuming compounds in the feed, e.g.
reactive protein materials and the like. Thus the actual acid rate
will depend on this factor. From a general process consideration
standpoint, the key process factor is the amount of "free catalyst"
in the system, i.e. free acid after consideration of any components
in the feedstock that will consume acid. Preferably the amount of
free acid remaining in the mixture is such that the resulting pH of
the slurry is in the range of about 0 to about 5, and most
preferably in the range of about 2 to about 3.
[0039] To shift the yield towards cellulosic sugar formation as
well as ester formation, and away from the acid consuming peptides
polymer breakdown, the acid content can be eliminated or
significantly reduced. In the absence or reduction of acid catalyst
(e.g., in the range from about 0.01 to 1 wt % based on the dry
weight of the feedstock), the temperature of the reaction is
increased to a range of about 240.degree. C. to about 300.degree.
C., preferably about 240.degree. C. to about 270.degree. C. and the
pressure of the reaction is increased to a range of about
1,000-2800 psi, preferably from about 1,100-1,900 psi, to promote
cellulose sugar polymer breakdown, derivatized sugar formation, and
triglyceride polymer breakdown for biodiesel (i.e., fatty acid
alkyl ester) formation.
[0040] The reaction mixture before reaction can also contain water
in an amount of at least about 3 wt % of the dry weight of the
feedstock, at least about 5 wt % of the dry weight of the
feedstock, or at least about 10 wt % of the dry weight of the
feedstock.
[0041] The pH of the mixture can be from about 0 to about 5,
preferably from about 1 to about 4, and most preferably from about
2 to about 3
[0042] The mixture is then reacted at elevated temperature, e.g. in
the range of about 140.degree. C. to about 300.degree. C., in the
range of about 160.degree. C. to about 275.degree. C., or in the
range of about 175.degree. C. to about 275.degree. C. A pressure
reactor system is used that will allow for the elevated temperature
and keep the alcohol from boiling. The pressure of reactor
operation is slightly in excess of the vapor pressure of the
alcohol of choice at the selected operating temperature (e.g. 20
psig over the vapor pressure). Typical pressures range from about
150 psig to about 650 psig, preferably from about 200 psig to about
500 psig, and most preferably from about 300 psig to about 400
psig. Pressures significantly in excess of the alcohol vapor
pressure are not required in the process approach.
[0043] The reactor system can be batch or continuous. There are
several conventional pressure vessel systems available that will
operate in batch and continuous modes and the process lends itself
to the "conventional" methods for this stage.
[0044] In addition, a continuous pipe-type reactor can be used to
carry out the reaction. The reactor is a pipe with sufficient
residence time to allow for the reaction to complete and is
operated under the target pressure and temperature range. The pipe
allows for reasonable reaction to occur with minimized vessel
complexity.
[0045] The reaction can be carried out for a period of about 5
minutes to 120 minutes and the reaction time can depend on the
selected reaction system and operating temperature. In a
conventional stirred tank reactor, the reaction time can be in the
range of 60 to 90 minutes for a batch reactor. At higher
temperatures, and corresponding pressures, the reaction time can be
reduced.
[0046] In the reaction, the alcoholysis, hydrolysis or both, of the
cellulosic material occur first. The alcohol, water or both act as
solvents for the acid catalyst, which attacks the sugar polymer
linkages to form cellulosic simple sugars (i.e., smaller sugar
polymers or monosaccharides). The acid catalyst is not selective
and will simultaneously perform esterification as well as perform
alcoholysis, hydrolysis, or both on the complex protein polymers
and shorten said protein polymers as well as produce amino
acids.
[0047] The free fatty acids (FFA) are the second materials to
convert to methyl (or other alcohol) ester, with the co-production
of water. Since the reaction is carried out at higher temperatures,
after the conversion of the FFA, the triglyceride (lipid) content
coverts to the methyl (or other alcohol) ester, with co-production
of glycerin. The protein polymers require the longest residence
time in the system if complete polymer linkage break down is
sought. Not to be bound by any theory, this description of the
reaction sequence is a general supposition.
[0048] A key finding and outcome of this acid esterification
approach is that during the course of the biodiesel formation
reactions, the presence of the acid also results in the
alcoholysis, hydrolysis, or both of the cellulosic material and
prepares the solid phase for subsequent fermentation. Acid
hydrolysis of cellulosic materials has been discussed in relation
to wood waste materials, switch grass, corn stovers, corn cobs, and
the like. Typically this hydrolysis is carried out in an aqueous
system where a single reaction is sought. In addition, depending on
the feedstock, there may be further conversion of the sugar
fractions to derivatized or dehydrated materials such as methyl
glucosides, ethyl glucosides and 5-(Hydroxymethyl)furfural, etc.
The extent will depend on the acid concentration, reaction time,
and reaction temperature for the particular feedstock being
processed.
[0049] The reaction product slurry (6) typically consists of the
algae pulp (containing cleaved cellulosic material, shortened
peptides, and amino acids), crude biodiesel, excess alcohol,
catalyst, water and glycerin. The resulting fatty acid alkyl esters
will be in the range of 10-50 wt % of the product slurry. The
resulting peptides/amino acids will be in the range of 0-50 wt % of
the product slurry. The resulting cleaved cellulosic materials will
be in the range of 0-50 wt % of the product slurry. The reaction
slurry is transferred to a Liquid/Solid Separation system. In this
step, the liquid fraction is separated from the solids portion.
Separation can be carried out using any number of standard
separation techniques, such as filtration, centrifugation,
combinations of each approach, and the like. Slight washing of the
solids, in the separation device, can be carried out with a small
amount of the alcohol (9A) recovered for recycle. The spent wash
would then be added into the crude biodiesel fraction.
[0050] The washed solids (7) are then sent to a demethylation step
wherein the methanol (or other alcohol) is removed from the
material via heating. Steam, from the aforementioned drying system
can be used for this step. The recovered alcohol (14) is
transferred to the Methanol (Alcohol) Recovery System. The solids
fraction (20) is transferred to the ethanol production portion of
the process.
[0051] The crude biodiesel liquid from the separation (8) is then
sent to a Biodiesel Demethylation/Bottoms Separation system. In
this process step, the liquid is first demethylated, i.e. alcohol
removal, and the vaporized alcohol (9) sent to the Methanol
(Alcohol) Recovery System. In the recovery system, the alcohol is
distilled to eliminate traces of moisture then returned (15) to the
reaction system for reuse.
[0052] When the alcohol is removed from the crude biodiesel, the
co-products, i.e. water and glycerin separate from the biodiesel
fraction. The catalyst reports to the aqueous/glycerin phase. This
two phase system is then treated in a separation system, e.g.
settling, centrifugation, and the like. The separated
water/glycerin/catalyst is referred to as the "bottoms" fraction.
This material (11) is transferred to a storage tank for subsequent
disposition. Depending on the feedstock, the bottoms from the
demethylation/bottoms separation step may contain high levels of
protein-bearing materials. In this case, the protein-rich fraction
(11A) can be sent to a separate surge and (if desirable) downstream
processes for further separation of the protein fraction from the
remainder of the material.
[0053] The demethylated biodiesel (10) is then sent to the
Biodiesel Distillation unit. In this step, the biodiesel is heated
to about 340.degree. F. to 360.degree. F. and subject to a high
vacuum in the range of 750 mm to 755 mm Hg (vacuum). Under these
conditions, the biodiesel fraction vaporizes and separates from the
various lower volatility impurities in the liquid.
[0054] The biodiesel vapor is then condensed using conventional
indirect heat exchangers with cooling supplied by cooling water.
The condensed biodiesel (12) is the transferred to biodiesel
storage tanks where the material is analyzed and confirmed for
shipment.
[0055] The demethylated solids (20) are transferred to a Solids
Neutralization/Separation system. In this stage, the pulp is mixed
with water (22) and a caustic solution (21), e.g. sodium hydroxide,
potassium hydroxide, etc. Ideally potassium hydroxide is used since
the resulting potassium salt, i.e. potassium sulfate, is a feed
source for the downstream fermentation process. The material is
neutralized to a pH of about 5.5 to 7.0. The target pH is that
which is consistent with the specific reagent used in the
fermentation process.
[0056] After neutralization, the slurry can be subjected to a
separation step, if required, to remove a portion of the aqueous
fraction with an accompanying removal of dissolved salts. This
solution (24) would be returned to the algae farms and the
potassium sulfate salt used as a food make-up source for the algae
material.
[0057] The neutralized pulp (23) then enters a Fermentation System
wherein it is mixed with conventional fermentation reagents (25),
e.g. yeasts, etc., then allowed to react in a conventional fashion.
Information relative to the conventional processing approaches are
available on numerous web-sites and a significant resource is the
Renewable Fuels Association (available on the WorldWideWeb at
rfa.org), which is the key industry trade association. The main
advantage is that a potentially lower cost feedstock has now been
made available that does not involve a current agricultural food
source commodity but rather second generation non food materials
such as algae or agricultural by-products.
[0058] In the fermentation system, the cellulosic sugars convert to
ethanol, with the co-production of carbon dioxide. The CO.sub.2
fraction would normally be vented back to the CO.sub.2 recovery
system for pick-up by the algae used in the carbon dioxide recovery
system if algae is used.
[0059] The fermentation slurry (26) is then sent to a Solid/Liquid
Separation system, and the non-fermented solids removed from the
liquid (beer) phase. Again, conventional separation methods may be
utilized, such as filters, centrifuges, and the like. The solids
fraction (27) can then be used elsewhere e.g. return to the algae
farms as a supplemental food source.
[0060] The fermented liquid (28) is transferred to an Evaporation
System wherein the alcohol phase is evaporated from the liquid,
along with some water. The aqueous fraction from the evaporator
(30) is returned to the algae farm system.
[0061] The alcohol fraction (29) is next treated in a
Distillation/Molecular Sieve system. In this process step, the
aqueous alcohol is first distilled, to produce a nominal 95%
ethanol material, then processed in a molecular sieve unit to
remove the remaining water and produce a 99.5%+ethanol product
(31). This operation is conventional and widely used in the current
ethanol production industry.
[0062] The residual solids from the fermentation stage will contain
the non-fermentable materials that may also contain significant
levels of useful proteins or amino acids. This solids fraction
could be combine with other animal feed products or, depending on
the exact nature of the material (based on the feedstock), further
processed, via drying, to produce a specialized feed product.
EXAMPLE 1
Algae Testing
[0063] The following example illustrates the basic process approach
and resulting product potential for algae feedstocks. Table 1
summarizes a series of tests conducted with algae feedstocks
(either fresh or salt water algae) using the process described
above. The initial pH was at 0.4. The temperature was between
140-180.degree. C. The pressure was between 200 and 500 psig. The
reaction time was between 1-2 hours. The starting algae contained
anywhere from 10% to 25% lipid content of which the FFA values
ranged from 5% to as much as 10%. The resulting recovered biodiesel
indicated that the contained oil was essentially completely
converted to the methyl ester. The percent conversion of oil to
fatty acid methyl ester was greater than 95%.
TABLE-US-00001 TABLE 1 Test 1 2 3 4 5 6 7 Dry algae (grams) 1,000
1,000 1,000 1,000 1,000 1,000 1,000 Acid catalyst (grams) 25 25 25
25 25 25 25 MeOH (grams) 1500 1400 1300 1200 1200 1200 1200
material subjected to temperature and pressure reaction conditions
reactor product separated in centrifuge, centrate taken to
demethylation two phases observed after demethylation, centrifuged
to separate ester from starch/protein Results Dry weight pulp 550
544 555 539 553 630.5 611 Fatty Acid Methyl Ester 222 219 224 217
223 94 98 (FAME) Starch 193 191 195 189 194 225 247.5 minor amounts
of material lost in handling through laboratory equipment
variations from tests 1-5 and tests 6-7 represent various fresh and
salt water algae. Process technique is capable of processing all
algae tested into FAME and starch
[0064] A sample of the solid residue material (i.e, pulp), that
contained the starch fraction was then mixed with water and
neutralized to a pH of about 6.5-7. Standard ethanol processing
yeast was added and the material was allowed to ferment for a
period of about 5 days. A small laboratory system was used wherein
the mixture was contained in a contained flask. A CO.sub.2
discharge tube was located on top of the flask and the CO.sub.2 was
discharged, via a dip leg, into a separate flask containing water.
This maintained a "water seal" on the fermentation flask and also
allowed for visual observation of CO.sub.2 bubbles, which, when
they stopped, indicated fermentation completion.
[0065] After the CO.sub.2 evolution stopped, the resulting
fermentation broth was filtered to remove residual solids. The
resulting liquid was heated to evaporate a mixture of ethanol and
water in a single stage evaporation flask with a condenser. The
condensed ethanol water phase contained about 8% ethanol. In
commercial practice, the weak ethanol would be treated in a
conventional evaporation/distillation/molecular sieve system (e.g.
the standard approach used in the conventional ethanol production
processes) to recover an anhydrous ethanol product. The techniques
are well established, and again reference is made to the Renewable
Fuels Association web-site.
[0066] About 50% of the contained starch converts to actual ethanol
(the remainder forming CO.sub.2). The expected ethanol recovery
from the algae feedstocks would be on the order of 10% by weight of
the algae. This conversion factor will depend on the potential
starch content of the starting algae and can vary between various
specifies of material. The recovery factors are for illustration
and are no way meant to limit the scope or require a specific
recovery.
EXAMPLE 2
Algae Soapstock Testing
[0067] Algae soapstock is a by-product of the conventional algae
oil processing route wherein the oil, containing high levels of
free fatty acids (FFA), is treated with an alkali solution to
neutralize the FFA and produce a "soapstock" that consists of
neutralized fatty acids. This material is separated from the
aqueous salt solution and typically recovered as a "soapstock"
material. A similar product is formed, in large amounts, from
soybean oil treatment and is sold, at relatively low cost, for
subsequent acidulation and recovery of the fatty acid values, as a
free fatty acid, for use in animal feeds or other lower valued
applications.
[0068] To assess the potential for soapstocks as feeds, a sample of
algae soapstock was obtained and processed in a manner similar to
that outlined for the algae (Example 1), with the exception that a
solids/liquid separation after the esterification stage was not
required. Briefly, the soapstock was initially neutralized with
sulfuric acid, then methanol and additional sulfuric acid was added
to provide excess acid (for catalyst). The mass of soapstock was
100 g. The mass of the initial sulfuric acid was 17 g to acidify
the soap. The mass of the methanol was 200 g. The additional mass
of the sulfuric acid used for the catalyst was 4 g. The initial pH
was below 1. The moisture content in the feedstock was on the order
of 10 wt % to 15 wt % of the weight of the feedstock, based on the
indicated supplier estimates (as supplied by Advanced Bio
Nutrition, Columbia, Md.). The mass was reacted for about 2 hours
at about 140.degree. C. under pressure sufficient to avoid methanol
evaporation.
[0069] The reaction mass was then neutralized with lime (to
eliminate any free sulfuric acid) and the material then separated
via a centrifuge into an aqueous phase, containing the water,
glycerin, and salt fraction, and an organic phase. The organic
phase containing essentially the biodiesel fraction was then
distilled to recover the ester fraction. The resulting biodiesel
was analyzed and met the ASTM standards for this material. In this
case there was no sugar or starch-like fraction so ethanol is not a
consideration for this feedstock.
[0070] Of considerable note with this test is that the
esterification was carried out in a relatively high free water
environment (i.e. in excess of 10% free water), since the
soapstock, as indicated, is a neutralized FFA from the oil feed.
This is of significance since for the conventional biodiesel
processing approaches, including the two stage processes consisting
of acid esterification followed by base transesterification, water
must be limited, typically to levels of less than 1% to 2% for acid
esterification and less than 0.5% for the transesterification
step.
EXAMPLE 3
Distillers Grain (Corn Feedstock)
[0071] Distillers grain is a major co-product from the production
of ethanol using the conventional corn feedstocks. Dry distillers
grain (DDG) is the material remaining after the fermentation
process and contains proteins, fats, fiber, ash, and other various
components. Much of this material is used in animal feed products,
but its value, compared to corn, is lower.
[0072] The quantities of this material are significant. For
example, a 100 million gallon/year ethanol facility using a dry
corn feed would produce on the order of 660 million pound/year of
DDG. In general, the DDG from corn contains about 10% to 11% fat
(oil content that is potentially convertible to biodiesel) and
about 45% to 50% carbohydrates (which if properly prepared could
serve as a fermentation feed).
[0073] It should be noted that with preparation, the resulting
sugars consist of both C6 and C5 fractions. The C6 fraction is
fermentable via the use of standard yeast materials. C5 sugars will
not ferment with yeasts only, and specialized enzymes have been
developed that will convert C5's. In addition, there are other
processes that have been developed that utilize C5 sugars to
produce other (non-ethanol) products.
[0074] Significant advantages could be brought about in the
biofuels industries if this feedstock could be further processed to
recover additional ethanol and produce a biodiesel product as well.
Incorporation of DDG treatment operations within existing ethanol
plants could further enhance the potential economic
attractiveness.
[0075] To assess the potential for the process to handle this feed,
samples of DDG from ethanol facilities (Verasun Energy of
Brookings, S. Dak. and White Energy of Dallas, Tex.) that processed
both corn and sorgum feedstocks were obtained. The basic testing
approach was as follows: [0076] The DDG was mixed with methanol and
sulfuric acid catalyst then reacted at elevated temperature and
pressure for about 2 hours. Typically the temperature was
maintained at about 200 deg C. The mass of the DDG was 100 grams,
the mass of the methanol was 200 grams, the mass of the sulfuric
acid was 8 grams, the initial pH was 0.5. [0077] After reaction,
the ester product mass was then filtered and washed with additional
alcohol to remove residual ester, sugars, etc. [0078] The solids
fraction was then set aside and would be used as a lower grade
animal feed in a commercial scenario. [0079] The liquid fraction
was then heated to remove excess alcohol (that would be recovered
for recycle in a commercial scenario). [0080] The mixture was then
neutralized to convert the free sulfuric acid to a neutral salt.
Neutralizing agents can include common alkalis, e.g. sodium
hydroxide, potassium hydroxide, sodium bicarbonate, potassium
carbonate, calcium oxide, calcium hydroxide, etc. The use of
calcium is ideal since it allows for subsequent animal feed
nutrition. The liquid, containing the esters, glycerine,
derivitized sugars, amino acids and the like was treated in an
additional separation stage to remove the ester fraction from the
non-ester fraction. Several methods are available for this
including solvent extraction, with e.g. hexane, or water
dissolution (preferred) to solublize the glycerin and sugar
fraction and allow for separation of the ester as an separate phase
(i.e. liquid/liquid separation). [0081] The ester fraction was then
treated in a distillation system to recover the ester as a high
grade material. [0082] The sugar, amino acid fraction (non-esters)
was then neutralized and, if a calcium material used, filtered to
remove the resulting calcium sulfate salt. This has the effect of
reducing the potential ash in the final amino acid. [0083] With the
reaction conditions employed, derivatized sugars, such as
5-(hydroxymethyl)furfural, were formed which will allow for
potential production and recovery of other products.
[0084] For the example test, the material used was the corn DDG and
contained about an 11 wt % oil fraction based on the total weight
of the DDG. The above process was carried out and after separation
and analysis, the resulting biodiesel fraction was about 10% by
weight of the feed, indicating that essentially all of the
contained oil was converted to the ester.
[0085] The ester fraction was then distilled and the recovered
biodiesel analyzed for total and free glycerin, since these are the
key components of successful ester production based on previous
laboratory testing. The material was well below the allowable ASTM
standards.
EXAMPLE 4
Rice Bran
[0086] Rice bran is another material that is a major co-product of
this grain processing industry. There are significant amounts of
this material produced in the U.S and especially overseas. The bulk
of this material is used in various feed additives and has a
relatively low value.
[0087] A sample of rice bran was processed in the same manner as
that used for the DDG sample (in Example 3). The composition of the
bran was somewhat similar to that of the DDG with respect to
carbohydrate content (i.e. potentially fermentable) but the oil
content was somewhat higher (typically 18 wt % or so).
[0088] After ester recovery, the material was distilled and the
biodiesel analyzed. Again the material was well within
specifications. Also, the amount of biodiesel produced was in line
with the expected value based on the oil content. Several tests
have indicated that the expected biodiesel production is about the
same (volume-wise) as the oil content in the starting
feedstock.
[0089] The remaining treated carbohydrate fraction would then
normally be subject to fermentation since the composition at this
stage is similar to the material obtained in the DDG
processing.
[0090] The disclosed process has been tested with a variety of
oil/starch-containing feedstocks as well as high soap materials.
The examples are shown for illustration purposes only and in no way
restrict the scope as to the potential feedstocks that are suitable
for this approach.
[0091] The present invention is not to be limited in scope by the
specific embodiments described herein. Indeed, various
modifications of the invention in addition to those described
herein will become apparent to those skilled in the art from the
foregoing description. Such modifications are intended to fall
within the scope of the appended claims.
[0092] All references cited herein, including all patents,
published patent applications, and published scientific articles,
are incorporated by reference in their entireties for all
purposes.
* * * * *