U.S. patent application number 11/971377 was filed with the patent office on 2008-08-07 for biofuel production methods.
This patent application is currently assigned to The Board of Regents of the Nevada System of Higher Education. Invention is credited to Narasimharao Kondamudi, Manoranjan Misra, Susanta Mohapatra, Gautam Priyadarshan.
Application Number | 20080184616 11/971377 |
Document ID | / |
Family ID | 39674952 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080184616 |
Kind Code |
A1 |
Misra; Manoranjan ; et
al. |
August 7, 2008 |
BIOFUEL PRODUCTION METHODS
Abstract
In some embodiments, the present disclosure provides methods for
producing biofuel from a biological material that includes protein
and a biofuel feedstock, such as triglycerides. In a specific
example, the biological material is hydrolyzed to obtain the
biofuel feedstock, such as by treatment with a base. Free fatty
acids or triglycerides are then extracted using an organic solvent.
The free fatty acids or triglycerides are converted to fatty acid
esters, useable as biofuel, by esterification or
transesterification, respectively. In a more specific example, the
biological material is converted to a biofuel in a one step process
by treating the biological material with base and an appropriate
alcohol. In some implementations, a disclosed method uses chicken
feathers obtained from a chicken processing operation as the
biological material.
Inventors: |
Misra; Manoranjan; (Reno,
NV) ; Priyadarshan; Gautam; (Reno, NV) ;
Kondamudi; Narasimharao; (Reno, NV) ; Mohapatra;
Susanta; (Reno, NV) |
Correspondence
Address: |
KLARQUIST SPARKMAN, LLP
121 SW SALMON STREET, SUITE 1600
PORTLAND
OR
97204
US
|
Assignee: |
The Board of Regents of the Nevada
System of Higher Education
|
Family ID: |
39674952 |
Appl. No.: |
11/971377 |
Filed: |
January 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60884173 |
Jan 9, 2007 |
|
|
|
60970790 |
Sep 7, 2007 |
|
|
|
Current U.S.
Class: |
44/308 |
Current CPC
Class: |
Y02P 30/20 20151101;
Y02E 50/13 20130101; C10G 2300/1011 20130101; C10L 1/026 20130101;
Y02E 50/10 20130101 |
Class at
Publication: |
44/308 |
International
Class: |
C10L 1/18 20060101
C10L001/18 |
Claims
1. A method of producing biofuel comprising: obtaining a biological
material, the biological material comprising protein and
triglycerides; hydrolyzing the biological material to obtain free
amino acids and a biofuel feedstock; and converting the biofuel
feedstock to fatty acid esters.
2. The method of claim 1, wherein the biological material comprises
feathers.
3. The method of claim 1, wherein the biological material comprises
poultry feathers.
4. The method of claim 1, wherein the biological material comprises
chicken feathers.
5. The method of claim 1, wherein the biological material comprises
feathers obtained from a poultry processing operation.
6. The method of claim 1, wherein hydrolyzing the biological
material comprises treating the biological material with a
base.
7. The method of claim 1, further comprising extracting the biofuel
feedstock from the hydrolyzed material using an organic
solvent.
8. The method of claim 7, wherein the organic solvent comprises at
least one of diethyl ether, dichloromethane, and methanol.
9. The method of claim 7, wherein the biofuel feedstock comprises
triglycerides and converting the biofuel feedstock to fatty acid
esters comprises a base catalyzed transesterification.
10. The method of claim 7, wherein the biofuel feedstock comprises
triglycerides and converting the biofuel feedstock to fatty acid
esters comprises an acid catalyzed transesterification.
11. The method of claim 7, wherein the biofuel feedstock comprises
triglycerides and converting the biofuel feedstock to fatty acid
esters comprises treating the triglycerides with a methoxide.
12. The method of claim 1, wherein the biofuel feedstock comprises
at least one of free fatty acids and triglycerides.
13. The method of claim 1, wherein the biofuel feedstock comprises
free fatty acids and converting the biofuel to fatty acid esters
comprises an acid catalyzed esterification.
14. The method of claim 1, wherein the biofuel feedstock comprises
free fatty acids, further comprising converting the free fatty
acids to glycerides and wherein converting the biofuel feedstock to
fatty acid esters comprises transesterifying the glycerides.
15. The method of claim 1, further comprising adding the fatty acid
esters to a biofuel derived from another source.
16. The method of claim 1, further comprising adding a stabilizer
to the fatty acid esters.
17. The method of claim 16, wherein the stabilizer comprises an
antioxidant.
18. A biofuel produced from the fatty acid esters of claim 1.
19. A method of producing biofuel comprising: obtaining chicken
feathers produced from a chicken processing operation; comminuting
the chicken feathers; hydrolyzing the chicken feathers to obtain
triglycerides; transesterifying the triglycerides to obtain a
biofuel; and extracting the triglycerides or the biofuel with an
organic solvent.
20. The method of claim 19, further comprising blending the biofuel
with another fuel.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of, and incorporates by
reference, U.S. Provisional Patent Application No. 60/884,173,
filed Jan. 9, 2007, and U.S. Provisional Patent Application No.
60/970,790 filed Sep. 7, 2007.
FIELD
[0002] The present disclosure describes methods of producing fuels
from biological materials. In specific examples, the present
disclosure provides methods for producing biodiesel from biological
sources which include protein and triglycerides, such as chicken
feathers.
TECHNICAL BACKGROUND
[0003] The United States produces 2-4 billion pounds of chicken
feathers from poultry industries. Science News, "Materials Take
Wing", Feb. 23, 2002, Vol. 161. In recent years it has been shown
that chicken feathers can be used for many applications, including
environmental application and filtration of heavy metals. P. Kar
& M. Misra, "Use of keratin Fiber for Separation of Heavy
metals from Water", Journal of Chemical Technology &
Biotechnology, 79, 1313-1319, 2004; M. Misra & P. Kar, "Avian
Keratin Protein Nano-Fiber for Environmental Application," Natural
Fibers, Plastics & Composite, 83-89, August 2000. However, much
of this material is unused, and can present disposal problems.
[0004] The availability and cost of petroleum based fuels continues
to be of concern. A number of efforts are underway to develop fuels
from other sources, such as hydrogen-based fuel sources, ethanol,
and biological based fuels, such as biodiesel. In particular,
various plant and animal oils and fats have been investigated as
potential sources of biofuel. However, the energy and resources
needed to produce biofuel can make it uneconomical to produce crops
specifically for biodiesel production. While waste oil and fats can
be used, their supply may be insufficient for mass production of
biofuel.
SUMMARY
[0005] The present disclosure provides methods for producing fuels,
such as biofuels, from biological materials. In a particular
disclosed method, biofuel is produced by hydrolysis of the
biological material to liberate triglycerides, free fatty acids, or
other substances which can be converted to fatty acid esters
useable as biofuels. In a particular implementation, the biological
material includes a protein, which is hydrolyzed using an alkaline
solution in some examples. The free fatty acids or triglycerides
are then esterified or transesterified, respectively, to produce
fatty acid esters useable as biofuel. For example, when
triglycerides are obtained from the biological material, the
triglycerides can be transesterified by treating them with a
strongly alkaline solution, although other methods are used in
further examples. When free fatty acids are obtained, the free
fatty acids may be esterified using an acid catalyzed reaction. In
a more particular implementation, triglycerides in the biological
source are converted to fatty acid esters in a one step process
using basic conditions and an alcohol, or derivative thereof,
bearing the appropriate functional group.
[0006] In a specific embodiment, a protein source is hydrolyzed
using a base. Free fatty acids or triglycerides are then extracted
using an organic solvent. Extracted free fatty acids are then
esterified, such as using acid catalyzed esterification and the
appropriate alcohol. Extracted triglycerides are then
transesterified, such as using a base catalyzed process.
[0007] In a further embodiment, the free fatty acids are converted
to glycerides, such as mono-, di-, or tri-glycerides by reaction
with glycerol under appropriate conditions. The gylcerides are then
transesterified to produce fatty acid esters, which may be used as
biofuels. In a specific example, the glycerides are transesterified
using a base catalyzed reaction.
[0008] The biological source may be any suitable biological
material having protein, such as a structural protein, such as
keratin, and triglycerides or fatty acids. In various examples the
biological source is hair, feathers, skin, hooves, claws, horns, or
scales. In a specific example, the protein source is feathers, such
as poultry feathers. In some examples, the feathers are obtained
from a poultry processing operation.
[0009] In some aspects of the present disclosure, the biological
source, or free fatty acids or triglycerides obtained therefrom, is
combined with another feedstock, such as a plant oil, such as a
vegetable oil, including soybean oil or rapeseed oil, coffee oil,
or an animal fat, such as chicken fat. The combined feedstock is
then converted to a biofuel, such as using an above-described
hydrolysis and/or esterification or transesterification procedure.
In further aspects, a biofuel produced from the above-described
biological material is combined with a biofuel derived from a
different feedstock, such as a plant oil, such as a vegetable oil,
including soybean oil or rapeseed oil, oil from coffee, or from an
animal fat, such as chicken fat.
[0010] The methods of the present disclosure can provide a number
of advantages. For example, the present disclosure can convert
chicken feathers, often treated as a waste product, into a high
value biofuel product. Accordingly, the supply of biofuel can be
increased without the expenditure of energy and other resources in
developing a feedstock specifically for use as a biofuel.
[0011] There are additional features and advantages of the subject
matter described herein that will become apparent as this
specification proceeds.
[0012] In this regard, it is to be understood that this is a brief
summary of several aspects of the subject matter described herein.
The various features described in this section and below for
various embodiments may be used in combination or separately. Any
particular embodiment need not provide all features noted above,
nor solve any particular set of problems in the prior art noted
above.
DESCRIPTION OF THE FIGURES
[0013] Various embodiments are shown and described in connection
with the following drawings in which:
[0014] FIG. 1 is a schematic diagram of various methods of
extracting a biofuel feedstock, such as free fatty acids or
triglycerides, from chicken feathers.
[0015] FIG. 2 is a schematic diagram of various methods of
converting triglycerides and free fatty acids to fatty acid
esters.
[0016] FIG. 3 is a process diagram of a disclosed method of
synthesizing biodiesel from chicken feathers.
[0017] FIG. 4 an HPLC chromatogram of a product produced using the
method of FIG. 3.
[0018] FIG. 5 is an HPLC chromatogram of a biodiesel product
produced using a method of the present disclosure.
[0019] FIG. 6 is an FTIR spectra of the biodiesel product of FIG.
5.
[0020] FIG. 7 is a GC-MS spectra of the biodiesel product of FIG.
5.
[0021] FIG. 8 is a photograph of a biodiesel sample obtained from
chicken feathers using a method of the present disclosure.
DETAILED DESCRIPTION
[0022] Unless otherwise explained, all technical and scientific
terms used herein have the same meaning as commonly understood by
one of ordinary skill in the art to which this disclosure belongs.
In case of conflict, the present specification, including
explanations of terms, will control. The singular terms "a," "an,"
and "the" include plural referents unless context clearly indicates
otherwise. Similarly, the word "or" is intended to include "and"
unless the context clearly indicates otherwise. The term
"comprising" means "including;" hence, "comprising A or B" means
including A or B, as well as A and B together.
[0023] Although methods and materials similar or equivalent to
those described herein can be used in the practice or testing of
the present disclosure, suitable methods and materials are
described herein. The disclosed materials, methods, and examples
are illustrative only and not intended to be limiting.
[0024] The present disclosure generally provides methods of
producing biofuels from biological materials. Typically, the
biological material includes triglycerides or fatty acids and a
protein, such as a structural protein. In a specific example, the
structural protein is keratin. Suitable biological sources include
hair, feathers, skin, hooves, claws, horns, or scales. In a
specific example, the protein source is feathers, such as poultry
feathers. In some examples, the feathers are obtained from a
poultry processing operation. In a more specific example, the
biological source is chicken feathers.
[0025] Chicken feathers typically constitute about 18 wt % of the
mass of a chicken. The feathers themselves contain about 84 wt %
protein, about 12 wt % triglycerides, and about 4 wt % ash,
phosphorous and trace metals. The triglycerides in the chicken
feathers can be converted to biodiesel using the disclosed methods.
Although the following methods specifically describe the use of
chicken feathers, similar methods may be used for other, similar,
biological sources.
[0026] As shown in FIG. 1, chicken feathers 110 can be converted to
triglycerides 120 or fatty acids 125 through a variety of pathways.
The chicken feathers 110 can be obtained from a variety of sources,
such as poultry processing operations. In some embodiments the
feedstock is pretreated to aid the subsequent conversion reactions.
For example, chicken feathers may be first crushed or ground, such
as by cryogenic grinding or grinding in a burr grinder, conical
burr grinder, blade grinder, or hammer mill. The feedstock may also
be pretreated by vibration. The chicken feathers may also be
subjected to one or more cleaning steps.
[0027] One conversion pathway 130 is base hydrolysis. Base
hydrolysis is typically carried out by refluxing a quantity of
chicken feathers with a concentrated aqueous solution of base, such
as an alkaline earth or alkali metal hydroxide. Other inorganic or
organic bases may also be used. In particular examples, the basic
solution is a NH.sub.4OH, KOH or NaOH solution, such as a solution
having a concentration of between about 2M and about 8M, such as
about 4M. The hydrolysis process is typically carried out from
about 1 hour to about 8 hours, such as about 4 hours. The chicken
feathers typically dissolve in the basic solution as the reaction
proceeds. After the reaction has reached a desired level of
completion, the reaction mixture is neutralized, such as by adding
an acid, such as an about 1M hydrochloric acid solution to about a
12M hydrochloric acid solution, such as a 6M hydrochloric acid
solution. Other mineral acids or organic acids can be used, if
desired, for the neutralization.
[0028] The triglycerides in the feathers are typically converted to
fatty acids during base hydrolysis. After neutralization, a solid
precipitate typically forms. Fatty acids and other components are
extracted from the neutralized reaction mixture, typically using
one or more organic solvents. Typical solvents include alcohols,
such as methanol, ethanol, and isopropanol; hydrocarbons, such as
paraffinic hydrocarbons having 4-8 carbons, such as hexane and
petroleum ether; chlorinated solvents, such as dichloromethane and
chloroform; ethers, such as diethyl ether; aldehydes and ketones,
such as methyl ethyl ketone and acetone; fluorinated compounds; and
mixtures thereof. In a specific example, a 5% by volume solution of
methanol in dichloromethane is used for the extraction.
[0029] In some methods, the solvent is selected to extract selected
components of interest. For example, relatively nonpolar solvents
may be used to extract fatty acids, yet avoid extraction of water
and other materials. Fatty acids thus obtained may require fewer
processing steps.
[0030] Extraction can occur in a batch or continuous process.
Suitable continuous processes include countercurrent extraction
processes. In some examples, the reaction mixture is refluxed with
solvent for a period of time, such as between about 30 minutes and
about 24 hours, such as between about 1 hour and about 8 hours. In
a particular example, the mixture is refluxed for about 1 hour.
[0031] After solvent extraction, the solvent may be removed prior
to further processing of the fatty acids. Solvent removal may be
accomplished by any suitable method, many of which are notoriously
well known in the art. For example, the solvent may be distilled
from the desired product. In particular implementations, solvent
removal occurs under reduced pressure, such as under a full or
partial vacuum, in order to reduce the temperature at which the
solvent distills, and thus the heat energy needed to volatilize the
solvent. In more particular implementations, rotary evaporators or
similar devices are used to remove solvent. When mixed solvent
systems are used, fractional distillation can be performed and
suitable distillation columns incorporated into the solvent removal
process or apparatus in order to aid separation of the different
solvent components. Fractional distillation can also be used to
purify the free fatty acids or to separate the fatty acids from
other components. Of course, if mixed recovery of solvents is not
of concern, fractional distillation need not be performed.
[0032] Solvent obtained from the above-described solvent removal in
process can be recycled into other parts of the system, such as
into the solvent extraction process. Appropriate choice of solvents
and operating conditions can result in substantial reuse of the
solvent, decreasing materials costs and potentially environmentally
harmful waste products. In some embodiments, over 85% of the
solvent used in the extraction step is recovered, such as over 95%.
The free fatty acids can then be esterified, such as using the
processes discussed below.
[0033] Acid hydrolysis 135 can be carried out in a manner similar
to base hydrolysis. Typically, the material is refluxed (such as at
about 110.degree. C.) in HCl, such as about 6M HCl, for about 4 to
about 24 hours. Neutralization may be carried out with a suitable
base, such as sodium hydroxide, potassium hydroxide, or other
organic or inorganic bases, including alkaline earth or alkali
metal oxides or hydroxides. The triglycerides thus obtained can be
extracted or purified as described above for the free fatty acids
produced during basic hydrolysis.
[0034] Another method 140 of isolating triglycerides from chicken
feathers involves refluxing the chicken feathers in N,N,-dimethyl
formamide for an extended period of time and then separating the
triglycerides using filtration. One procedure for carrying out this
process is disclosed in U.S. Pat. No. 3,970,614, incorporated by
reference herein.
[0035] A method 150 involves extracting triglycerides from chicken
feathers using water at high temperature and pressure. Suitable
techniques are described in Yin et al., "Self-organization of
Oligopeptides Obtained on Dissolution of Feather Keratins in
Superheated Water," Biomacromolecules, 8 800-806 (2007),
incorporated by reference herein. For example, chicken feathers can
be hydrolyzed using superheated or supercritical water.
[0036] In a specific example, the chicken feathers are placed in a
suitable pressure vessel, such as a stainless steel vessel, and
heated until the pressure cell reaches a temperature of about
220.degree. C. and a pressure of about 22 bar. The feathers are
held in this state until a desired degree of hydrolysis has
occurred, such as about 2 hours. The triglycerides can be separated
from other components, such as proteins and amino acids, using
suitable techniques, such as extraction or gravity separation, such
as using a hydrocyclone or a separatory funnel. Additional detail
regarding procedures for dissolving polymers, including biological
polymers such as keratin, using this type of methodology can be
found in Rastogi et al., "Dissolution of Hydrogen-Bonded Polymers
in Water: A Study of Nylon-4,6," Macromolecules 37, 8825-8828
(2004), expressly incorporated by reference herein in its
entirety.
[0037] Path 170 illustrates yet another method of obtaining
triglycerides from chicken feathers. Chicken feathers are treated
with urea and 2-mercaptoethanol, as described in Schrooyen et al.,
"Partially Carboxymethylated Feather Keratins. 2. Thermal and
Mechanical Properties of Films," J. Agric. Good Chem. 49, 221-230
(2001), incorporated by reference herein. After solubilization,
excess reagents can be removed through suitable means, such as
dialysis.
[0038] A one step procedure 180 can be used to extract
triglycerides and convert them to fatty acid esters. For example,
the chicken feathers may be refluxed with an alcohol bearing the
desired functional group, such as methanol, and an esterification
regent or catalyst, such as sodium hydroxide, ammonium hydroxide,
or sodium methoxide. Although other esterification reagents or
catalysts can be used, methoxide-based transesterification
procedures can help reduce the nitrogen and sulfur content of the
resulting biofuel.
[0039] The triglycerides 120 can be subjected to further processing
steps prior to transesterification. For example, the triglycerides
120 can be washed to remove free fatty acids and other materials.
In some embodiments, the wash is carried out with an alcohol, such
as methanol or ethanol, or acetic acid. Multiple washings can
increase the amount of free fatty acid removed, thus increasing the
pH towards neutral. In some embodiments, the triglycerides 120 are
washed until the pH is sufficiently neutral, such as to a pH of at
least about 6.7. Particularly when water sensitive materials are
used in the subsequent transesterification step, the triglycerides
120 can be dried, such as using molecular sieves or similar
materials, such as zeolites, silica gels, or acidic clays, or other
drying agents, such as sodium sulfate, calcium chloride, magnesium
sulfate, potassium carbonate, and calcium sulfate. If needed or
desired, the pH of the triglycerides 120 can be adjusted, such as
to a neutral pH, using standard methods, such as addition of an
acid or base. The triglycerides 120 can be further purified or
fractionated, such as using distillation, as described in U.S. Pat.
No. 3,704,132, incorporated by reference herein.
[0040] After solvent removal or any other desired processing steps,
the triglycerides 120 are converted to esters, useable as biofuel,
in a transesterification process. Any suitable transesterification
process may be used in the methods of the present disclosure, many
of which are notoriously well known in the art. For example, a
number of acid and base catalysts are disclosed in U.S. Pat. No.
5,424,420 and in Schuchardt et al., J. Braz. Chem. Soc., 9(1),
199-210 (1998), each of which is incorporated by reference herein.
FIG. 2 illustrates a number of methods for converting triglycerides
210 and fatty acids 215 to fatty acid esters 220.
[0041] The hydrolysis processes described above, as well as the
esterification and transesterification processes described below,
can be carried out in the presence of mechanical mixing or
ultrasonic treatment. Such treatment can, for example, aid in
mixing the fatty acid or triglyceride with the alcohol, catalyst,
other reagent or solvent, as triglycerides may be immiscible, or
have limited miscibility, in the alcohol. Agitation may be
accomplished by a paddle or blade stirrer attached to a motor, such
as a motor operating at about 100 rpm to about 1000 rpm, such as
about 300 rpm to about 700 rpm or about 400 rpm to about 600 rpm.
Stirring may be accomplished by other means, such as using a
magnetic stirring device, or other means of agitation used, such as
a shaker.
[0042] In further embodiments, ultrasonication, optionally in
combination with agitation, is applied during all or a portion of a
hydrolysis, esterification, or transesterification process.
Suitable ultrasonication devices are available from Hielscher
Ultrasonics GmbH of Teltow, Germany and Branson Ultrasonics
Corporation of Danbury, Conn. Ultrasonicators of any suitable power
can be used, such as those having a frequency of 16-45 kHz, power
100-500 W, 20-400 mW/cm.sup.2. Ultrasonication power and duration
can be selected based on various factors, including the alcohol
used for transesterification, the nature of the catalyst, the
reaction temperature, and the process conditions of the reaction,
such as whether the transesterification occurs as a batch or
continuous process. For example, the reaction size or reactant flow
rate may influence the power or duration of ultrasonication
used.
[0043] Ultrasonication may have other benefits, such as reducing
the reaction time and reducing the amount of catalyst or alcohol
used in the esterification or transesterification. In some
examples, ultrasonication is carried out while the reactants are
under pressure, such as a gauge pressure of about 1 bar to about 3
bar.
[0044] The hydrolysis, esterification, and transesterification
reactions may be carried out under any suitable conditions. In some
methods the reactions are carried out at room temperature or
higher, optionally in a pressurized vehicle, such as an autoclave.
The use of higher temperatures and pressures may aid in
solubilizing the components of the feedstock.
[0045] In typical esterification or transesterification reactions,
an alcohol containing the desired substituent group is added to the
free fatty acid or triglyceride. Such alcohols can be represented
by R--OH, where R is the desired ester group, typically a short
chain hydrocarbon, such as a C.sub.1-C.sub.4 hydrocarbon, which may
be linear or branched. In more particular examples, the alcohol is
methanol or ethanol. Alcohol is typically maintained in a
stoichiometric excess, such as at a ratio of alcohol to
triglyceride or free fatty acid of between about 3:1 and about
40:1, such as about 6:1 to about 12:1 or between about 9:1 and
about 12:1. In a specific example, the ratio of alcohol to
triglyceride or free fatty acid is about 9:1. In further examples,
the transesterification or esterification mixture includes from
about 20% to about 60% alcohol by volume.
[0046] In some embodiments, the transesterification is carried out
in the presence of a cosolvent. A cosolvent may, for example, aid
in mixing of the alcohol and triglyceride, which can enhance the
reaction rate. Suitable cosolvents include pyridine,
tetrahydrofuran, hexane, bis-(dimethylsilyl)trifluoroacetamide, and
methyl tert-butyl ether.
[0047] With continuing reference to FIG. 2, in at least certain
methods, transesterification is accomplished using acid 230 or base
240 catalysis, each of which is further described below. Base
catalyzed transesterification 240 is typically better for
relatively clean triglyceride sources, such as those which lack
substantial amounts of free fatty acids and are relatively
water-free. Base catalyzed transesterification is typically faster,
more complete, and produces a higher purity product compared with
acid catalyzed transesterification. However, acid catalysis 230 can
be useful when the starting material is not well suited for the
base catalyzed process 240.
[0048] Transesterification process 230 is catalyzed using a
catalytic amount of acid, which may be an organic acid, a mineral
acid, or a Lewis acid. Suitable acids include aluminum chloride,
benzyl sulfonic acid, boron trifluoride, dichloroacetic acid,
hydrochloric acid, iodic acid, methanesulfonic acid, phosphoric
acid, nitric acid, acetic acid, citric acid, malic acid, adipic
acid, tartaric acid, fumaric acid, p-toluene sulfonic acid, stannic
chloride, sulfonic acid, sulfuric acid, and trichloroacetic acid.
In at least some examples, the acid or acids used to catalyze the
transesterification have an acid dissociation constant (pK.sub.a)
of about 2 or less, such as about 1 or less.
[0049] Transesterification process 240 is carried out using a base
catalyzed method, such as using organic bases, Lewis bases, or
inorganic bases. Suitable base catalysts include alkali metal
hydroxides, such as sodium hydroxide and potassium hydroxide, and
alkaline earth metal oxides and hydroxides, such as magnesium
oxide, calcium hydroxide, calcium oxide, barium hydroxide, and
strontium hydroxide.
[0050] Transesterification also may be accomplished using a
combination of base 240 and acid 230 catalysis. For example, a
portion of the triglycerides may be transesterified using an acid
catalyst and then a basic catalyst added to the reaction mixture.
The basic catalyst is typically added in an amount sufficient to
act as a catalyst for the transesterification and an additional
amount to neutralize the acid catalyst. Salts formed from the
acid-base reaction can be removed following the
transesterification, such as by washing the fatty acid ester with
water. Suitable techniques for such acid/base catalyzed
transesterification are described in U.S. Patent Publication US
2006/0094890, incorporated by reference herein.
[0051] A further transesterification method 250 involves treating
the triglyceride with an alkoxide of a hydrocarbon alcohol having
the desired ester group, such as methoxides or ethoxides.
Methoxides are typically prepared from alkali metals, such as
sodium and potassium. In particular examples, the
transesterification is carried out using sodium methoxide.
Alkoxides typically react with water and thus, in some
implementations, the transesterification process 250 uses
water-free or substantially water-free materials. Molecular sieves
or similar materials, such as zeolites, silica gels, or acidic
clays, or other drying agents, such as sodium sulfate, calcium
chloride, magnesium sulfate, potassium carbonate, and calcium
sulfate, may be included in the reaction vessel in order to help
remove water from the reaction environment.
[0052] The transesterification reaction is carried out for a time
sufficient to allow the reaction to reach a desired level of
completion. The reaction time may vary based on the reactants (such
as the catalyst and alcohol used) and the reaction conditions,
including the temperature of the reaction and the nature of the
reaction vessel. Typically, reaction is carried out for a period of
about 1 minute to about 72 hours, such as between about 5 minutes
and about 2 hours or between about 5 minutes and about 15 minutes.
Reaction temperature is typically between about 10.degree. C. and
about 200.degree. C., such as between about 25.degree. C. and about
75.degree. C. The reaction temperature may depend on the alcohol
used, the reaction time, and other process conditions. For example,
acid catalyzed transesterification can take substantially longer
than base catalyzed methods, and are typically carried out at
higher temperatures.
[0053] When the transesterification is catalyzed, a stoichiometric
amount of catalyst is not needed. In particular examples, the
amount of catalyst is from about 1 wt % to about 40 wt % based on
the amount of triglyceride to be transesterified, such as between
about 1 wt % and about 10 wt % or between about 1 wt % and about
2.5 wt %. For non-catalytic transesterifications, the amount of
transesterification is typically included in at least a
stoichiometric amount, and is added in stoichiometric excess in
more particular examples.
[0054] In some implementations, excess catalyst is used to
neutralize free fatty acids or other materials in the triglyceride.
The presence of free fatty acids is determined, in some
embodiments, by measuring the pH of the triglyceride. Acidic pH,
such as less than about 6.7, can indicate the presence of free
fatty acid. Catalyst, or other base, can be added, when base
catalyzed transesterification is used, to neutralize the free fatty
acid, such as adding base until the pH of the triglyceride is
sufficiently neutral.
[0055] In further examples, other transesterification processes are
used in place of or in addition to those discussed above. For
example, transesterification can be carried out by enzymatic
processes 260. In addition, transesterification can be carried out
using supercritical methanol 270, such as at about 350.degree. C.
and about 35 Mpa. Supercritical methanol transesterification is
typically complete in a relatively short time, such as about 4
minutes. Transesterification using supercritical methanol can be
advantageous as it does not typically require acid or base and can
thus simplify subsequent purification or processing steps. Suitable
techniques for enzymatic processes 260 and supercritical methanol
processes 270 are described in Marchetti et al., "Possible Methods
for Biodiesel Production," Renewable and Sustainable Energy Reviews
11 1300-1311 (2007) and references cited therein, each of which is
incorporated by reference herein.
[0056] When free fatty acids 215 are used to produce biofuel,
Fischer esterification 280 using an acid catalyst and an
appropriate alcohol is typically employed. For example, the free
fatty acids 215 may be refluxed in methanol with a catalytic amount
of acid, which is typically a mineral acid such as HCl or
H.sub.2SO.sub.4, although other acid catalysts may be used. The
reaction is allowed to proceed until a desired degree of
esterification has been reached, such as between about 5 minutes
and about 24 hours, such as about 8 hours. Molecular sieves or
similar materials, such as zeolites, silica gels, or acidic clays,
or other drying agents, such as sodium sulfate, calcium chloride,
magnesium sulfate, potassium carbonate, and calcium sulfate, may be
included in the reaction vessel in order to help remove water from
the reaction environment and help drive the reaction to
completion.
[0057] In some cases, it may be desirable to convert free fatty
acids to glycerides, such as mono-, di-, or tri-glycerides before
converting the feedstock to fatty acid esters. This can be
accomplished using glycerolysis step 290. Glycerolysis can be
performed according to any suitable method. Suitable enzymatic
methods are described in Fadiloglu et al., "Reduction of Free Fatty
Acid Content of Olive-Pomace Oil by Enzymatic Glycerolysis," Food
Science and Technology International 9(1) 11-15 (2003) and Damstrup
et al., "Process Development of Continuous Glycerolysis in an
Immobilized Enzyme-Packed Reactor for Industrial Monoacylglycerol
Production," Journal of Agricultural and Food Chemistry A-G (Aug.
23, 2007), each of which is incorporated by reference herein.
Glycerolysis may also be accomplished by adding glycerol to the
free fatty acids and heating the mixture to a relatively high
temperature, such as above about 200.degree. C., such as about
250.degree. C. to about 260.degree. C. Addition of a suitable
catalyst, such as zinc powder or zinc chloride, can decrease the
needed temperature or reaction time. Once the free fatty acids have
been converted to glycerides, the glycerides may be transesterified
using the techniques shown in FIG. 2 and described above.
[0058] Although adding additional steps to the biofuel production
process, glycerolysis of the free fatty acids can provide a number
of advantages. For example, base catalyzed, or other non-acidic
transesterification processes can be easier to implement on an
industrial scale, as they can be less prone to corrode process
equipment. In addition, once triglycerides are formed from the free
fatty acids, the chicken feather triglycerides can be combined with
other feedstocks in a transesterification process. Another
potential advantage of transesterification is that yields from
transesterification processes, such as base catalyzed
transesterification, can be higher than Fisher esterification of
free fatty acids.
[0059] After the transesterification or esterification reaction has
reached a desired level of completion, the fatty acid ester product
is separated from reactants and reaction byproducts in a separation
process. In some implementations, the products can be neutralized,
such as by an acidic wash when a basic catalyst is used in the
transesterification or a basic wash when acid catalyst is used.
Washing with water, such as hot water, can also be used to remove
undesired materials, such as acid, from the reaction products.
[0060] Upon standing, such as for about 12, about 24, about 36,
about 48, or about 72 hours, or more, one or more layers may form,
such as a fatty acid ester layer, a layer which includes soaps,
such as glycerin, and a layer that includes other components, such
as water, salts, and unreacted alcohol. Various processes may be
used to remove the desired layer or layers, such as decantation,
draining at the appropriate level, or sequential removal of
layers.
[0061] Depending on the processes and materials used in the
esterification or transesterification, separation of the layers may
be difficult or take longer than desired. Therefore, in some
examples, gravity separation devices are used to aid in separating
components of the reaction products. The term gravity separator, as
used herein, refers to devices which separate materials based on
density (specific gravity). Suitable gravity separation devices
include separatory funnels, hydrocyclones, and centrifuges.
Ultrasonication can also aid in layer separation.
[0062] In further embodiments, the fatty acid ester product is
extracted with an organic solvent, which in some embodiments is
selected as described above for extraction of triglycerides. In
particular examples, the solvent is diethyl ether or hexane.
Solvent extraction may take place after other steps, such as
neutralization, as described above. Solvent extraction of the fatty
acid ester may produce a more pure product.
[0063] Glycerin formed from the transesterification process, and
isolated during the separation process, can be further isolated,
purified, and put to other beneficial uses. For example, glycerin
is used in foods, plastics, lacquers, pharmaceuticals, toothpastes,
tobacco, resins, cosmetics, cellulose processing, and
explosives.
[0064] After separation, the fatty acid ester can be further
purified or treated. For example, the fatty acid ester can be
neutralized, particularly if neutralization was not carried out
during the separation process. When transesterification is carried
out using a base or alkoxide, neutralization is typically carried
out by washing the fatty acid ester product with one or more dilute
acids, such as an aqueous solution of a dilute acid. Suitable acids
include organic, inorganic, and Lewis acids, such as tannic acid,
citric acid, salicylic acid, malic acid, maleic acid, acetic acid,
salicylic acid, and hydrochloric acid. In a particular example, a
neutralization solution is used in an amount of between about 20
vol % to about 40 vol % by volume of the amount of raw triglyceride
material used in the transesterification reaction. Acid is added to
this neutralization solution, in some embodiments, having a
concentration of about 0.1 mM to about a 1 M, such as between about
0.5 mM to about 50 mM.
[0065] Correspondingly, a basic wash can be used to neutralize the
product of an acid catalyzed transesterification or esterification.
Mineral, organic, or other suitable bases, such as Lewis bases, can
be used for the neutralization, such as alkaline and alkaline earth
metal hydroxides, such as sodium hydroxide or potassium
hydroxide.
[0066] Additional purification steps can be performed on the crude
fatty acid ester in order to make it more suitable as a biofuel.
For example, the fatty acid ester can be treated with activated
carbon or other substances to remove impurities from the product.
Additional water washes can be performed on the fatty acid ester,
such as to remove residual salts, catalyst, alcohol, or soaps. The
fatty acid ester product can also be dried, such as using molecular
sieves or similar materials, such as zeolites, silica gels, or
acidic clays, or other drying agents, such as sodium sulfate,
calcium chloride, magnesium sulfate, potassium carbonate, and
calcium sulfate. The product can also be fractionated to remove
impurities or isolate different fuel fractions.
[0067] In particular methods, the biofuel resulting from the
disclosed methods conforms to the Avian Biodiesel (ABD-06)
standard. According to some aspects of the present disclosure,
biofuels produced according to the disclosed methods are mixed with
other fuels, including biofuels obtained from other sources. For
example, the disclosed fuels may be mixed with biofuels obtained
from plant oils, including vegetable oils, such as soybean oil or
rapeseed oil, oil from coffee beans, or from animal fats (including
chicken fat).
[0068] In yet further embodiments, the feedstock, such as chicken
feathers, is mixed with another biofuel feedstock, such as plant
oils, such as vegetable oils, including soybean oil or rapeseed
oil, coffee beans, or animal fat, and the combined feedstock is
converted to biofuel. In some implementations the combined
feedstock is treated with alkali and the resulting product
transesterified to produce a biofuel. In at least some
implementations, the use of such a combined feedstock can enhance
biofuel production or increase the quality (or otherwise adjust the
properties of) the resulting biofuel.
[0069] In order to enhance the stability or firing properties of
the resulting biofuel, various additives can be added to the
biofuel produced according to the disclosed methods. For example,
antioxidants or other stabilizers can be added to the biofuel.
Suitable antioxidants and stabilizers include
2,6-di-tert-butyl-4-methylphenol, BIOSINEOX (available from
Antioxidants Aromas and Fine Chemicals (Pty) Ltd. of Richards Bay,
South Africa), tocopherols, pyrogallol, propylgallate,
tert-Butylhydroquinone, and ETHANOX (available from Albemarle
Corporation of Pasadena, Tex.).
EXAMPLES
Example 1
[0070] In the present Example, chicken feathers were crushed in a
vibrated mill to produce fine size fibrous materials. The fibrous
material was conditioned with NaOH for an extended time at room
temperature. The hydrolyzed product was mixed with freshly prepared
methoxide (methanol plus NaOH). The mixed product was conditioned
for 24 hours. A schematic of the process is shown in FIG. 3.
[0071] Two layers formed after the 24 hour conditioning period. The
top fraction was a clear biofuel material corresponding to
esterified products. The lower thick layer included glycerin and
other substances. The top layer was analyzed using High Pressure
Liquid Chromatography (HPLC) to determine the quality of biofuel
fraction. The resulting chromatogram, shown in FIG. 4, illustrates
that the biodiesel was of good quality.
Example 2
[0072] In this Example, chicken feathers were mixed in a
pressurized autoclave in the presence of water and NaOH. The mixed
product was heated at 60-70.degree. C. (external temperature
200-300.degree. C.) for 20-30 minutes. After that time, the
hydrolyzed and dissolved product was mixed with sodium methoxide
(methanol and NaOH) for several hours at 60-70.degree. C. The
mixture was then cooled to room temperature. A good and high
quality biofuel (esterified product) was noticed. The presence of
biofuel was confirmed by HPLC.
Example 3
[0073] In this Example chicken feathers were mixed with methanol to
which sodium hydroxide was added. The mixture was conditioned for
several hours. After conditioning, sodium methoxide was added. The
resulting mixture was mixed for a long time at 25-60.degree. C. The
product was then cooled to room temperature. A clean biofuel layer
(esterified product) and glycerin layer were observed. The biofuel
layer was analyzed by HPLC, confirming the formation of a high
quality biofuel oil.
Example 4
[0074] In this Example, chicken feathers were mixed with alkaline
media, consisting of sodium hydroxide and water. The mixture was
ultrasonically treated. The hydroxide product was then treated with
freshly prepared sodium methoxide for a long time at a temperature
of 25-70.degree. C. After cooling, a biofuel layer was obtained.
The oil layer was washed several times. The oil was determined to
be of high quality.
Example 5
[0075] In this Example, chicken feathers were mixed with ammonium
hydroxide. The mixture was allowed to stand for an extended time.
The hydrolyzed product was then mixed with freshly prepared
ammonium methoxide for an extended period of time. The mixture was
then allowed to settle for about 24 hours. Water was added to help
settle the layers.
[0076] Three different layers were observed. The upper layer was
oil corresponding to esterified products. The middle layer
contained water plus oil. The lower layer contained glycerin and
other products. HPLC analysis confirmed that the top oil layer
consisted of high quality oil.
Example 6
[0077] In this Example, chicken feathers were mixed with water and
sodium hydroxide. The mixture was refluxed for 2-24 hours. The
hydrolysis product was neutralized with hydrochloric acid. Some of
the free sulfur groups in cysteines were converted into hydrogen
sulfide, which evolved during the neutralization process. Fatty
acids were extracted with ether (dichloromethane, chloroform or a
5% solution of methanol in dichloromethane can also be used for
extraction). Three different layers were observed. The upper layer
was ether containing fatty acids, the middle layer was
polypeptides, and the lower layer was water containing free amino
acids. The fatty acids were collected from the top layer (ether) by
evaporating the solvent under vacuum. Fatty acids were refluxed
with methanol in presence of an acid (e.g. HCl, H.sub.2SO.sub.4,
etc.). The quality of the biodiesel produced was measured using
HPLC, the results of which are shown in FIG. 5. The product was
also analyzed by FTIR, which, as shown in FIG. 6, indicates the
presence of the ester group and the hydrocarbon chains. The
composition of the methyl esters of fatty acids was analyzed by
GC-MS. Retention times and corresponding esters structure are shown
in FIG. 7.
Example 7
[0078] In this Example, chicken feathers were hydrolyzed by
refluxing with hydrochloric acid for 6 hours. Fatty acids were
extracted using ether (dichloromethane, chloroform or 5% solution
of methanol in dichloromethane can also be used for extraction).
Three different layers were observed. The upper layer was ether
containing fatty acids, the middle layer was polypeptides, and the
lower layer was water containing free amino acids and glycerin.
Fatty acids were obtained from layer one by evaporating the solvent
under vacuum. Fatty acids were then refluxed with methanol in the
presence of concentrated sulfuric acid (acid catalyzed
esterification) to produce biodiesel.
Example 8
[0079] In this Example, chicken feathers were hydrolyzed by
refluxing with methanol and sodium hydroxide for 2-12 hours.
Methanol was evaporated and fatty acids were extracted with diethyl
ether (dichloromethane, chloroform or 5% solution of methanol in
dichloromethane can also be used for extraction). Fatty acids were
then refluxed with methanol in the presence of concentrated
sulfuric acid (acid catalyzed esterification) to produce biodiesel.
A photograph of the biodiesel in methanol obtained from chicken
feathers is shown in FIG. 8.
[0080] It is to be understood that the above discussion provides a
detailed description of various embodiments. The above descriptions
will enable those skilled in the art to make many departures from
the particular examples described above to provide apparatuses
constructed in accordance with the present disclosure. The
embodiments are illustrative, and not intended to limit the scope
of the present disclosure. The scope of the present disclosure is
rather to be determined by the scope of the claims as issued and
equivalents thereto.
* * * * *