U.S. patent application number 16/816216 was filed with the patent office on 2020-09-17 for methods for making free fatty acids from soaps using thermal hydrolysis followed by acidification.
The applicant listed for this patent is Inventure Renewables, Inc.. Invention is credited to Cory O'Neil BLANCHARD, John BROWN, Ryan Alexander LONG, William Rusty SUTTERLIN.
Application Number | 20200291327 16/816216 |
Document ID | / |
Family ID | 1000004856420 |
Filed Date | 2020-09-17 |
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United States Patent
Application |
20200291327 |
Kind Code |
A1 |
SUTTERLIN; William Rusty ;
et al. |
September 17, 2020 |
METHODS FOR MAKING FREE FATTY ACIDS FROM SOAPS USING THERMAL
HYDROLYSIS FOLLOWED BY ACIDIFICATION
Abstract
Provided are methods, processes and systems for treating a
soapstock. In alternative embodiments, provided are systems and
methods for treating a soapstock to generate free fatty acids
and/or fatty acid derivatives, e.g. fatty acid alkyl esters. In
alternative embodiments, provided are systems and methods for
realizing the full fatty acid yield of a soapstock by first
converting substantially all of the saponifiable material in a
soapstock to salts of fatty acids (soaps) and acidulating the soaps
to generate free fatty acids and/or fatty acid derivatives, e.g.
fatty acid alkyl esters, wherein the soapstock comprises soaps and
saponifiable lipids, e.g. glycerides and/or phospholipids, and the
generating of free fatty acids and/or fatty acid is achieved.
Inventors: |
SUTTERLIN; William Rusty;
(Hoover, AL) ; LONG; Ryan Alexander; (Northport,
AL) ; BLANCHARD; Cory O'Neil; (Birmingham, AL)
; BROWN; John; (Tuscaloosa, US) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Inventure Renewables, Inc. |
Tuscaloosa |
AL |
US |
|
|
Family ID: |
1000004856420 |
Appl. No.: |
16/816216 |
Filed: |
March 11, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16331703 |
Mar 8, 2019 |
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PCT/US2017/050321 |
Sep 6, 2017 |
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16816216 |
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62385883 |
Sep 9, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C11B 3/001 20130101;
C11B 3/04 20130101; C11B 13/02 20130101; C11C 1/025 20130101; C11C
3/00 20130101; C11B 1/10 20130101; C11C 3/003 20130101; Y02W 30/74
20150501; C11B 13/00 20130101; C11C 1/04 20130101 |
International
Class: |
C11C 1/02 20060101
C11C001/02; C11C 3/00 20060101 C11C003/00; C11B 1/10 20060101
C11B001/10; C11B 3/04 20060101 C11B003/04; C11C 1/04 20060101
C11C001/04 |
Claims
1. A method for generating free fatty acids from a mixed lipid
feedstock using a thermal hydrolysis reaction, the method
comprising: (a) providing an aqueous solution or mixture comprising
a mixed lipid feedstock, and wherein optionally the mixed lipid
feedstock comprises: a soapstock; a triglyceride comprising
material; a saponifiable material, optionally a glyceride or a
phospholipid; a tall oil, optionally a "liquid rosin" tall oil, a
soapstock; a gums product, optionally a chemically or enzymatically
derived gums product; a crude biodiesel; a fatty acid, optionally
from a distillation bottom; a fat splitter emulsion, optionally
purged from fat splitter due to accumulation when recycled; or, any
combination thereof, and optionally the mixed lipid feedstock
comprises a soapstock, a wash-water comprising soaps or a
combination thereof, optionally generated during the chemical
refining of a crude natural oil, and optionally the mixed lipid
feedstock is derived from a biomass, a crude natural oil, or a
plant or an animal source, optionally a tallow; and optionally the
mixed lipid feedstock is derived from enzymatic degumming of edible
and inedible oils; and (b) heating and pressurizing the aqueous
solution or mixture comprising the mixed lipid feedstock in a
thermal hydrolysis reaction under conditions comprising sufficient
pressure and temperature to generate a first reaction mixture
comprising a free fatty acid and/or a soap, optionally a fatty acid
salt, and/or a glyceride, optionally a monoacylglycerol (MAG), a
diacylglycerol (DAG), or a triacylglycerol (TAG), wherein the
thermal hydrolysis reaction is carried out at a temperature in the
range of between about 20.degree. C. to about 600.degree. C., and
at a pressure of between about 300 to about 2000 psig (about 20.7
bar to about 137.9 bar), and for between about 1 second (sec) to
about 3000 minutes (min), or between about 1 min to about 300 min,
or between about 5 min to 200 min, and optionally the amount of
water in the thermal hydrolysis reaction is between about 2:1
water-to-total dissolved solids (TDS) present in the mixed lipid
feedstock to about 15:1 TDS, or about 10:1 TDS; or between about
1:1 TDS present in the mixed lipid feedstock to about 100:1 TDS,
and optionally a solvent is added to the thermal hydrolysis
reaction in an amount of between about 0.01:1 water-to-total
dissolved solids (TDS) present in the mixed lipid feedstock to
about 100:1 TDS, or about 10:1 TDS.
2. The method of claim 2, further comprising: (a) an acidification
reaction that takes place after or during or simultaneous with the
thermal hydrolysis step, comprising: (1) providing an acid or an
acid solution or a gas capable of forming an acid when mixed with
water, optionally a carbon dioxide (CO.sub.2) or a stack gas; and
(2) combining or mixing the first reaction mixture with the acid or
acid solution or the gas, optionally CO.sub.2, or mixing the first
reaction mixture with the acid or acid solution or the gas,
optionally CO.sub.2, to have an acidulation reaction and to
generate a second reaction mixture, wherein the first reaction
mixture is combined or mixed with the acid or acid solution or the
gas, optionally CO.sub.2, for a sufficient amount of time to
acidulate, optionally partially, or substantially all of, the soap
in the first reaction mixture to generate free fatty acids from the
acidulated soaps, and optionally the pH of the acidulation reaction
mixture is less than about pH 5, or is between about pH 1 to pH 6,
or is about pH 1, 2, 3, 4, 5 or 6, and optionally the amount of the
gas is sufficient to increase the pressure of the reaction mixture,
optionally in a reaction vessel, in which the acidulation reaction
is being carried out to between about 0 and about 2000 psig. (b)
the method of (a), further comprising mixing the second reaction
mixture with an alcohol to form a third reaction mixture comprising
fatty acid alkyl esters, wherein optionally the mixing is done
under conditions comprising between about 240.degree. C. to about
350.degree. C., or 200.degree. C. to 400.degree. C., and a pressure
of between about 1400 psi to about 3000 psi, and optionally
substantially all of the free fatty acids are esterified to
generate fatty acid alkyl esters, optionally, fatty acid methyl
esters, and optionally the alcohol comprises methanol, ethanol or a
mixture thereof; (c) the method of (a) or (b), further comprising
separating, isolating, and/or purifying the free fatty acids and/or
the fatty acid alkyl esters into separate fractions; or (d) a
pre-treatment acidification reaction step for treating the mixed
lipid feedstock before the thermal hydrolysis reaction, wherein the
pre-treatment acidification reaction step comprises: (1) (i)
providing an acid or an acid solution or a gas capable of forming
an acid when mixed with water, optionally a carbon dioxide
(CO.sub.2) or a stack gas; and (ii) combining or mixing the mixed
lipid feedstock with the acid or acid solution or the gas,
optionally CO.sub.2, or mixing the mixed lipid feedstock with the
acid or acid solution or the gas, optionally CO.sub.2, to have an
acidulation reaction and to generate a pre-treated mixed lipid
feedstock, wherein the mixed lipid feedstock is combined or mixed
with the acid or acid solution or the gas, optionally CO.sub.2, for
a sufficient amount of time to acidulate, optionally partially, or
substantially all of, the soap in the mixed lipid feedstock; or (2)
electrolysis, optionally using a hydrogen evolving cathode (HEC)
electrolysis unit, of the mixed lipid feedstock for a sufficient
amount of time to acidulate, optionally partially, or substantially
all of, the soap in the mixed lipid feedstock, and optionally the
pH of the pre-treatment acidulation reaction mixture is less than
about pH 5, or is between about pH 1 to pH 6, or is about pH 1, 2,
3, 4, 5 or 6, and optionally the amount of the gas is sufficient to
increase the pressure of the pre-treatment reaction mixture,
optionally in a reaction vessel, in which the pre-treatment
acidulation reaction is being carried out to between about 0 and
about 2000 psig.
3. The method of claim 1, wherein the natural oil or crude natural
oil comprises a vegetable oil, wherein optionally the vegetable oil
comprises a soybean oil, a canola oil, a rapeseed oil, a corn oil,
a rice oil, a sunflower oil, a peanut oil, a sesame oil, a palm
oil, an algae oil, a jatropha oil, a castor oil, a safflower oil, a
grape seed oil or any combination thereof, and optionally the
natural oil or crude natural oil comprises castor oil, and
optionally a free fatty acid generated is ricinoleic acid
(12-hydroxy-9-cis-octadecenoic acid).
4. The method of claim 1, wherein the mixed lipid feedstock further
comprises additional water, a phospholipid and/or an unsaponifiable
material.
5. The method of claim 2, wherein the acid or acid solution
comprises carbonic acid, and optionally the carbonic acid is
generated by adding carbon dioxide (CO.sub.2) to the first reaction
mixture, thereby causing the carbon dioxide to react with water in
the first reaction mixture to form carbonic acid, and optionally a
source of the carbon dioxide (CO.sub.2) comprises a stack gas or a
flue gas, or a gaseous CO.sub.2 emitted from an industrial process
or an oven, a furnace, a boiler, a steam generator, a coal fired
power plant, an ethanol plant, a brewery, or an industrial process
wherein a gaseous waste stream comprising CO.sub.2 is emitted, and
optionally the carbon dioxide is added to the first reaction
mixture, optionally as a liquid, a carbon dioxide gas, or as a
gaseous flow of carbon dioxide into the reaction vessel.
6. The method of claim 1, wherein the heating and pressurizing of
the mixed lipid feedstock is done in a single vessel, or
sequential, different, reaction vessels; and optionally the
pre-treatment and the thermal hydrolysis are done in a single
reaction vessel, and optionally the pre-treatment, the thermal
hydrolysis and the post-thermal hydrolysis acidulation are done in
the same reaction vessel.
7. The method of claim 1, wherein: (a) the soapstock is obtained
from the alkaline neutralization of a crude natural oil; (b) the
gums product comprises phospholipids, and optionally the gums
product is generated during the degumming of a natural oil; or (c)
the mixed lipid feedstock comprises, or further comprises, one or
more compounds produced as a byproduct from the water washing of
crude biodiesel, wherein optionally the compounds comprise
soapstock, monoglycerides, diglycerides, triglycerides and/or fatty
acid alkyl esters or any combination thereof.
8. The method of claim 1, wherein the method is a batch or a
continuous process.
9. The method of claim 1, wherein the heating and pressurizing the
mixed lipid feedstock takes place in conditions comprising:
temperature in a range of between about 100.degree. C. to
500.degree. C., or 200.degree. C. to 400.degree. C., or 240.degree.
C. to 300.degree. C., or at about 260.degree. C.; and/or a pressure
of between about 650 and 750 psig, between about 750 and 850 psig,
between about 850 and 1000 psig, between about 1000 and 1500 psig,
or between about 1500 psig and 1800 psig; and/or for between about
20 and 30 minutes, or between about 160 and 180 minutes, or between
about 300 minutes and 500 minutes.
10. The method of claim 2, wherein the amount of gas is sufficient
to increase the pressure of the reaction mixture, optionally in a
reaction vessel, in which the acidulation reaction is being carried
out to between about 10 and 1000 psig, about 20 to about 600 psig,
about 30 to about 500 psig, about 40 to about 400 psig, about 50 to
about 300 psig, about 60 to about 200 psig, about 60 to about 150
psig, about 70 to about 140 psig, about 80 to about 120 psig, about
90 to about 110 psig, or about 100 psig.
11. The method of claim 2, wherein the acidulation reaction is
carried out at a temperature in the range of between about
5.degree. C. to about 400.degree. C., e.g. about 10.degree. C. to
about 90.degree. C., about 15.degree. C. to about 70.degree. C.,
about 20.degree. C. to about 60.degree. C., or about 25.degree. C.
to about 40.degree. C.
12. The method of claim 2, wherein: (a) the acid or acid solution
comprises an organic and/or an inorganic acid or a mineral acid, a
hydrochloric acid, a sulfuric acid, a formic acid or sodium
bisulfate, and optionally when a stack gas comprising N.sub.2O,
NO.sub.x, optionally NO.sub.2, SO.sub.x, optionally SO.sub.2, or
H.sub.2S is used the N.sub.2O, NO.sub.x, SO.sub.x, or H.sub.2S
reacts with water in the acidulation reaction mixture to form
equivalent aqueous acid species; (b) after a reaction vessel has
reached a desired temperature and pressure to carry out the
acidulation step, the resulting reaction mixture is agitated, or
otherwise mixed in order to maximize the contacting of the soaps
with the acid, optionally carbonic acid, and optionally the mixture
can be agitated using a spinning blade mixer, and optionally the
mixture is agitated for between about 10 minutes to about 200
minutes, e.g. between about 25 minutes to about 150 minutes, or
between about 20 minutes to about 60 minutes, or about 30 minutes;
(c) after the acidulation reaction, and optionally following an
agitation step, the contents of the acidulation reaction,
optionally in a reaction vessel, are allowed to settle or partition
allowing for the formation or separation of a lipid layer, a lipid
phase or a lipid component, and an aqueous layer, an aqueous phase
or an aqueous component, wherein the lipid layer or lipid phase
floats on the top of the aqueous layer, and optionally the lipid
layer or lipid phase comprises free fatty acids and any
non-acidulated soaps, and the aqueous layer comprises water,
glycerol, phosphate salts, sodium bicarbonate, sodium carbonate or
other equivalent salts, unsaponifiable material, optionally waxes
and sterols, and dissolved carbonic acid; (d) the method of (c),
wherein before or after the reaction products of the acidulation
reaction, optionally in a reaction vessel, are allowed to settle or
partition, the reaction products of the acidulation step are
transferred to a separation vessel, optionally a decanter, a
settler or an equivalent, or a centrifuge where the lipid layer or
lipid phase or component separates or partitions out from an
aqueous phase or component; or the acidulation product mixture is
not transferred to a separate vessel in order to separate lipids in
the lipid layer or lipid phase from reaction products in an aqueous
phase or component, and after the lipid layer or lipid phase or
component separates or partitions out from the aqueous phase or
component the aqueous layer is drained from the bottom of the
reaction vessel and the lipid layer or the lipid phase or component
is recovered as the reaction product; (e) further comprising
multiple acidulation reactions, optionally between about 1 and 20
additional acidulation reactions, or about 1, 2, 3, 4, 5, 6, 7 or 8
or more additional acidulation reactions; or (f) after the
acidulation reaction the reaction vessel is depressurized, allowing
for dissolved carbonic acid or other gaseous acid to separate out
of the solution as gaseous CO.sub.2, or equivalents, and optionally
captured CO.sub.2 is recycled for use in the further acidulation
reactions.
13. The method of claim 1, wherein the solvent added to the thermal
hydrolysis reaction is a polar, optionally a methanol, or a
non-polar, optionally a hexane, solvent.
14. The method of claim 2, wherein the thermal hydrolysis reaction
and the acidulation reaction take place sequentially; or, the
thermal hydrolysis reaction and the acidulation reaction can take
place simultaneously as a "one pot" reaction in one reaction
vessel.
15. The method of claim 12, wherein the lipid layer or lipid phase
or component, optionally comprising unreacted soaps, is transferred
to an electrolysis unit, optionally a hydrogen evolving cathode
(HEC) electrolysis unit, wherein the lipid layer or lipid phase or
component is reacted with an anolyte such that the unreacted soaps
generate free fatty acids, and optionally the electrolysis step
converts substantially all, or about 90%, 95%, 98% or more of the
unreacted soaps to free fatty acids, wherein optionally the anode
comprises a mixed metal oxide (MMO) layer coated onto a stable
metal substrate, optionally a titanium, and optionally the anolyte
comprises a sodium or potassium sulfate, a sodium or potassium
nitrate, or a sodium or potassium chloride.
16. The method of claim 12, wherein the lipid layer or lipid phase
or component is transferred to an electrolysis unit, optionally a
hydrogen evolving cathode (HEC) electrolysis unit, comprising a
vessel or suitable container comprising an anode, optionally an
anode vessel, and a vessel or other suitable container comprising a
cathode, optionally an cathode vessel, separated by a selective
filtration membrane, optionally a polytetrafluoroethylene (PTFE)
membrane, wherein optionally the anode comprises a mixed metal
oxide (MMO) layer coated onto a stable metal substrate, optionally
a titanium, and optionally the cathode comprises a titanium or a
Monel alloy, or any substrate that is stable in a reducing
environment.
17. The method of claim 12, wherein the aqueous phase or component,
or multiple aqueous phases if collected from multiple acidulation
reactions, is treated to remove water, wherein optionally the
treatment of the aqueous phase or component to remove water is by a
drying method, optionally evaporation via falling film, forced
recirculation flashing or equivalent, thereby generating a product
comprising sodium bicarbonate, and optionally the product is dried
further to generate a sodium bicarbonate product that is
substantially free of any water, optionally less than about 20%
water or less than about 10% water, and optionally the drying is
done using a fluidized bed dryer, a lyophilizer, a spray dryer, or
a rotary drum dryer.
18. The method of claim 12, wherein the aqueous phase or component,
or multiple aqueous phases if collected from multiple acidulation
reactions, is treated using a filtration, optionally a membrane
filtration system, a nano- or microfiltration system or a
size-exclusion filtration system, and optionally the filtration is
operationally in-line operating continuously with the acidulation
step such that aqueous phase generated in the acidulation reaction,
or each acidulation reaction if more than one acidulation reaction,
is treated immediately after or during the point at which the
aqueous phase is separated from the lipid phase, and optionally the
aqueous phase is collected and treated in a single batch, and
optionally soaps and/or other saponifiable material rejected by the
filtration, optionally soaps and/or other saponifiable material
that do not pass through a membrane of a filter system, are
returned to the lipid layer or lipid phase or component for
subsequent acidulation reactions, thereby increasing the overall
fatty acid yield.
19. The method of claim 12, wherein the aqueous phase or component,
or multiple aqueous phases if collected from multiple acidulation
reactions, is treated with calcium hydroxide, optionally a slaked
lime, to form a calcium precipitate, optionally a calcium phosphate
(Ca.sub.x(PO.sub.4).sub.x) precipitate, and optionally the
lime-treated aqueous phase or component, or multiple aqueous phases
if collected from multiple acidulation reactions, is subjected to
an oxidation step, optionally a Fenton oxidation wherein hydrogen
peroxide and Fe.sup.2+ ions are used to catalyze OH radical
formation.
20. The method of claim 12, wherein the aqueous phase or component,
or multiple aqueous phases if collected from multiple acidulation
reactions, is subjected to electrolysis to recover monovalent ions
as a base for a value added product, wherein electrical current is
passed through a cathode, the water is reduced, thereby generating
hydroxide ions; and as monovalent ions, optionally sodium or
potassium, are pushed across a membrane separating an anode vessel
from a cathode vessel into the cathode vessel, they react with the
generated hydroxide ions to generate a corresponding hydroxide
base, optionally a sodium hydroxide or a potassium hydroxide, and
optionally the hydroxide base separated out, recovered and/or
isolated.
Description
RELATED APPLICATIONS
[0001] This U.S. National Phase patent application claims priority
under 35 U.S.C. .sctn. 371 to Patent Convention Treaty (PCT)
International Application PCT/US2017/050321, filed Sep. 6, 2017,
now pending, which claims the benefit of priority under 35 U.S.C.
.sctn. 119(e) to U.S. Provisional Application Ser. No. 62/385,883,
now expired, filed Sep. 9, 2016. The aforementioned applications
are expressly incorporated herein by reference in their entirety
and for all purposes.
TECHNICAL FIELD
[0002] The present invention generally provides processes for
treating a soapstock and making free fatty acids. Provided are
systems and methods for treating a soapstock or any composition
comprising a mixture of triglycerides of fatty acids to generate
free fatty acids and/or fatty acid derivatives, e.g. fatty acid
alkyl esters such as fatty acid methyl esters. Provided are systems
and methods for realizing the full fatty acid yield of a soapstock
by first thermally hydrolyzing the saponifiable material in a
soapstock and then acidulating the soaps to generate free fatty
acids and/or fatty acid derivatives, e.g. fatty acid alkyl esters.
In alternative embodiments, the soapstock comprises a soap or any
saponifiable lipid, e.g. glycerides, triglycerides and/or
phospholipids, and the generating of free fatty acids and/or fatty
acid is achieved.
BACKGROUND
[0003] Crude (unrefined) animal and vegetable oils (referred to
herein collectively as "natural oils") are typically subjected to a
variety of processing steps to remove specific undesirable
components of the crude oil prior to sale. The type, number, and
sequencing of processing steps can vary depending on the crude oil
feedstock, refinery type (e.g. physical vs. alkaline) and
configuration, target product markets, and the like. In general,
crude natural oils are refined to remove excess quantities of
"gums" (comprised primarily of phospholipids), free fatty acids, as
well as various coloring components and volatile compounds.
[0004] Once removed from the crude oil, the refining byproducts are
either sold directly into low-value markets such as animal feed, or
further processed into higher-value products. Two major byproducts
of the chemical refining processes of natural oils are soapstock
and gums. In most natural oil refineries utilizing the chemical
refining process, phosphoric acid or an equivalent acid is added to
the crude oil to increase the solubility of the phospholipids
(gums) in water. Next, a strong base, typically sodium hydroxide
(NaOH) is added, reacting with the free fatty acids in the oil to
form soaps (salts of free fatty acids). Water is then added to the
oil to remove the soaps and solubilized gums. Soapstock is
typically acidulated to generate free fatty acids. Gums are
typically sold into low-value animal feed markets or upgraded to
food-grade emulsifiers, e.g. lecithin.
[0005] In most chemical refining configurations, additional waste
streams are generated which represent low- or negative-value
byproducts. For example, it typically necessary to perform an
additional water wash on the oil after the majority of the gums and
soaps have been removed. The lipid content of this washwater
(referred to as Soapstock Makeup) can contain from about 5% to
about 20% soaps and other lipids, but the lipid content is
generally not sufficiently high to justify the costs of further
processing into value added products. In addition, all of the above
referenced byproduct streams from the chemical refining process
contain various amounts of saponifiable (triglyceride-comprising)
material that are not converted to free fatty acids.
SUMMARY
[0006] In alternative embodiments, provided are processes and
systems for treating or processing a soapstock. In alternative
embodiments, provided are systems and methods for treating a
soapstock, or any triglyceride comprising material, to generate
free fatty acids and/or fatty acid derivatives, e.g. fatty acid
alkyl esters such as fatty acid methyl esters.
[0007] In alternative embodiments, provided are methods and systems
for generating free fatty acids from a mixed lipid feedstock. In
alternative embodiments, a mixed lipid feedstock, e.g., from an
animal or plant source, is provided. The feedstock is first heated
and pressurized (hereinafter referred "thermal hydrolysis") to
produce fatty acids. The reacted first mixture is combined with an
acid or acid solution, thereby acidulating soaps unreacted in the
first step to generate additional free fatty acids.
[0008] In alternative embodiments, the method further comprises
additional steps, e.g., as described herein. For example, in
alternative embodiments, the generated free fatty acids can be
esterified with an alcohol to form a second mixture, thereby
esterifying substantially all of the free fatty acids to generate
fatty acid alkyl esters. The generated free fatty acids can be
separated, isolated, or purified into separate fractions. The mixed
lipid feedstock can be selected from the group consisting of a
soapstock, a washwater comprising soaps, and a combination thereof
as generated during the chemical refining of a crude natural oil.
The mixed lipid feedstock can be a tall oil soapstock. The crude
natural oil can be a vegetable oil. The vegetable oil can be
selected from the group consisting of soybean oil, canola oil,
rapeseed oil, corn oil, rice oil, sunflower oil, peanut oil, sesame
oil, palm oil, algae oil, jatropha oil, castor oil, safflower oil,
grape seed oil, and any combination of vegetable oils. The mixed
lipid feedstock can further comprise: water, soaps, phospholipids,
saponifiable material, and unsaponifiable material. The acid can be
carbonic acid. The carbonic acid can be generated by adding carbon
dioxide to the thermal hydrolysis product mixture, thereby causing
the carbon dioxide to react with the water in the thermal
hydrolysis product mixture to form carbonic acid.
[0009] In alternative embodiments, also provided are methods and
systems for generating free fatty acids from a mixed lipid
feedstock. In alternative embodiments, a mixed lipid feedstock is
provided and subjected to thermal hydrolysis. The mixture is
allowed to react in a reaction vessel. In alternative embodiments,
carbon dioxide, if used, is introduced into the reacted mixture in
the reaction vessel to form a first carbonic acid within the
reaction vessel. Alternatively, a carbonic acid can be mixed with
the reacted mixture within the reaction vessel. In alternative
embodiments, the carbonic acid and reacted mixture is allowed to
settle within the reaction vessel. A first aqueous layer can be
drained from the reaction vessel.
[0010] In alternative embodiments, the carbon dioxide is introduced
as a gaseous flow of carbon dioxide into the reaction vessel. The
carbon dioxide can be introduced as a liquid flow of carbon dioxide
into the reaction vessel. In a second acidulation reaction, carbon
dioxide can be introduced into the reacted mixture in the reaction
vessel to form a second carbonic acid within the reaction vessel.
The second carbonic acid (of the second acidulation reaction) can
be mixed with the reacted mixture within the reaction vessel. The
second carbonic acid and reacted mixture can be allowed to settle
within the reaction vessel. A second aqueous layer (of the second
acidulation reaction) can be drained from the reaction vessel. In
an alternative embodiment, an objective is to reach an equilibrium
between carbonic acid and sodium bicarbonate, and this can be
achieved through multiple acidulation steps as required by the
different feedstocks, for example, optionally up to 20 acidulation
steps, or more if desired or necessary, can be used to achieve a
high, or the highest possible, yield of fatty acids.
[0011] In alternative embodiments, provided are methods for
generating free fatty acids from a castor oil. In alternative
embodiments, the castor oil is reacted via thermal hydrolysis in a
reaction vessel. Carbon dioxide is introduced into the reacted
mixture in the reaction vessel to form a carbonic acid within the
reaction vessel. The carbonic acid and the reacted mixture is then
mixed within the reaction vessel. The carbonic acid and reacted
mixture is allowed to settle within the reaction vessel. An aqueous
layer is drained from the reaction vessel.
[0012] In alternative embodiments, the carbon dioxide is introduced
as a gaseous or liquid flow of carbon dioxide into the reaction
vessel. In a second acidulation reaction, carbon dioxide can be
introduced into the reacted mixture in the reaction vessel to form
a second carbonic acid within the reaction vessel. The second
carbonic acid can be mixed with the reacted mixture within the
reaction vessel. The second carbonic acid and reacted mixture can
be allowed to settle within the reaction vessel. A second aqueous
layer (from the second acidulation reaction) can be drained from
the reaction vessel.
[0013] In alternative embodiments, provided are methods and
processes for generating free fatty acids from a mixed lipid
feedstock using a thermal hydrolysis reaction, the method or
process comprising:
[0014] (a) providing an aqueous solution or mixture comprising a
mixed lipid feedstock, and
[0015] wherein optionally the mixed lipid feedstock comprises: a
soapstock; a triglyceride comprising material; a saponifiable
material (optionally a glyceride or a phospholipid); a tall oil
("liquid rosin" or tall oil) soapstock; a gums product (optionally
chemically or enzymatically derived); a crude biodiesel; a fatty
acid (optionally from a distillation bottom); a fat splitter
emulsion (optionally purged from fat splitter due to accumulation
when recycled); or, any combination thereof, [0016] and optionally
the mixed lipid feedstock comprises a soapstock, a wash-water
comprising soaps or a combination thereof, optionally generated
during the chemical refining of a crude natural oil, [0017] and
optionally the mixed lipid feedstock is derived from a biomass, a
crude natural oil, or a plant or an animal source (optionally a
tallow); [0018] and optionally the mixed lipid feedstock is derived
from enzymatic degumming of edible and inedible oils; and
[0019] (b) heating and pressurizing the aqueous solution or mixture
comprising the mixed lipid feedstock in a thermal hydrolysis
reaction under conditions comprising sufficient pressure and
temperature to generate a first reaction mixture comprising a free
fatty acid and/or a soap (a fatty acid salt), and/or a glyceride
(optionally monoacylglycerol (MAG), diacylglycerol (DAG), or
triacylglycerol (TAG)),
[0020] wherein the thermal hydrolysis reaction is carried out at a
temperature in the range of between about 20.degree. C. to about
600.degree. C., and at a pressure of between about 300 to about
2000 psig (about 20.7 bar to about 137.9 bar), and for between
about 1 second (sec) to about 3000 minutes (min), or between about
1 min to about 300 min, or between about 5 min to 200 min,
[0021] and optionally the amount of water in the thermal hydrolysis
reaction is between about 2:1 water-to-total dissolved solids (TDS)
present in the mixed lipid feedstock to about 15:1 TDS, or about
10:1 TDS; or between about 1:1 TDS present in the mixed lipid
feedstock to about 100:1 TDS,
[0022] and optionally a solvent is added to the thermal hydrolysis
reaction in an amount of between about 0.01:1 water-to-total
dissolved solids (TDS) present in the mixed lipid feedstock to
about 100:1 TDS, or about 10:1 TDS.
[0023] In alternative embodiments, methods and processes as
provided herein further comprise an acidification reaction that
takes place after or during (simultaneous with) the thermal
hydrolysis step, comprising:
[0024] (a) providing an acid or an acid solution or a gas capable
of forming an acid when mixed with water, optionally a carbon
dioxide (CO.sub.2) or a stack gas; and
[0025] (b) combining or mixing the first reaction mixture with the
acid or acid solution or the gas, optionally CO.sub.2, or mixing
the first reaction mixture with the acid or acid solution or the
gas, optionally CO.sub.2, to have an acidulation reaction and to
generate a second reaction mixture, wherein the first reaction
mixture is combined or mixed with the acid or acid solution or the
gas, optionally CO.sub.2, for a sufficient amount of time to
acidulate (partially, or substantially all of) the soap in the
first reaction mixture to generate free fatty acids from the
acidulated soaps,
[0026] and optionally the pH of the acidulation reaction mixture is
less than about pH 5, or is between about pH 1 to pH 6, or is about
pH 1, 2, 3, 4, 5 or 6,
[0027] and optionally the amount of the gas is sufficient to
increase the pressure of the reaction mixture, optionally in a
reaction vessel, in which the acidulation reaction is being carried
out to between about 0 and about 2000 psig.
[0028] In alternative embodiments, methods and processes as
provided herein further comprise mixing the second reaction mixture
with an alcohol to form a third reaction mixture comprising fatty
acid alkyl esters, wherein optionally the mixing is done under
conditions comprising between about 240.degree. C. to about
350.degree. C., or 200.degree. C. to 400.degree. C., and a pressure
of between about 1400 psi to about 3000 psi,
[0029] wherein optionally substantially all of the free fatty acids
are esterified to generate fatty acid alkyl esters, optionally,
fatty acid methyl esters,
[0030] and optionally the alcohol comprises methanol, ethanol or a
mixture thereof.
[0031] In alternative embodiments, methods and processes as
provided herein further comprise separating, isolating, and/or
purifying the free fatty acids and/or the fatty acid alkyl esters
into separate fractions.
[0032] In alternative embodiments, methods and processes as
provided herein further comprise a pre-treatment acidification
reaction step for treating the mixed lipid feedstock before the
thermal hydrolysis reaction, wherein the pre-treatment
acidification reaction step comprises:
[0033] (a) (i) providing an acid or an acid solution or a gas
capable of forming an acid when mixed with water, optionally a
carbon dioxide (CO.sub.2) or a stack gas; and
[0034] (ii) combining or mixing the mixed lipid feedstock with the
acid or acid solution or the gas, optionally CO.sub.2, or mixing
the mixed lipid feedstock with the acid or acid solution or the
gas, optionally CO.sub.2, to have an acidulation reaction and to
generate a pre-treated mixed lipid feedstock, wherein the mixed
lipid feedstock is combined or mixed with the acid or acid solution
or the gas, optionally CO.sub.2, for a sufficient amount of time to
acidulate (partially, or substantially all of) the soap in the
mixed lipid feedstock,
[0035] and optionally the pH of the pre-treatment acidulation
reaction mixture is less than about pH 5, or is between about pH 1
to pH 6, or is about pH 1, 2, 3, 4, 5 or 6,
[0036] and optionally the amount of the gas is sufficient to
increase the pressure of the pre-treatment reaction mixture,
optionally in a reaction vessel, in which the pre-treatment
acidulation reaction is being carried out to between about 0 and
about 2000 psig; or
[0037] (b) electrolysis (optionally using a hydrogen evolving
cathode (HEC) electrolysis unit) of the mixed lipid feedstock for a
sufficient amount of time to acidulate (partially, or substantially
all of) the soap in the mixed lipid feedstock.
[0038] In alternative embodiments, the natural oil or crude natural
oil comprises a vegetable oil, wherein optionally the vegetable oil
comprises a soybean oil, a canola oil, a rapeseed oil, a corn oil,
a rice oil, a sunflower oil, a peanut oil, a sesame oil, a palm
oil, an algae oil, a jatropha oil, a castor oil, a safflower oil, a
grape seed oil or any combination thereof, and optionally the
natural oil or crude natural oil comprises castor oil, and
optionally a free fatty acid generated is ricinoleic acid
(12-hydroxy-9-cis-octadecenoic acid).
[0039] In alternative embodiments, the mixed lipid feedstock
further comprises additional water, a phospholipid and/or an
unsaponifiable material.
[0040] In alternative embodiments, the acid or acid solution
comprises carbonic acid, and optionally the carbonic acid is
generated by adding carbon dioxide (CO.sub.2) to the first reaction
mixture, thereby causing the carbon dioxide to react with water in
the first reaction mixture to form carbonic acid, and optionally a
source of the carbon dioxide (CO.sub.2) comprises a stack gas or a
flue gas, or a gaseous CO.sub.2 emitted from an industrial process
or an oven, a furnace, a boiler, a steam generator, a coal fired
power plant, an ethanol plant, a brewery, or an industrial process
wherein a gaseous waste stream comprising CO.sub.2 is emitted.
[0041] In alternative embodiments, the heating and pressurizing of
the mixed lipid feedstock is done in a single vessel, or
sequential, different, reaction vessels; and optionally the
pre-treatment and the thermal hydrolysis are done in a single
reaction vessel, and optionally the pre-treatment, the thermal
hydrolysis and the post-thermal hydrolysis acidulation are done in
the same reaction vessel.
[0042] In alternative embodiments, the carbon dioxide is added to
the first reaction mixture, optionally as a liquid, a carbon
dioxide gas, or as a gaseous flow of carbon dioxide into the
reaction vessel.
[0043] In alternative embodiments, the soapstock is obtained from
the alkaline neutralization of a crude natural oil.
[0044] In alternative embodiments, the gums product comprises
phospholipids, and optionally the gums product is generated during
the degumming of a natural oil.
[0045] In alternative embodiments, the mixed lipid feedstock
comprises, or further comprises, one or more compounds produced as
a byproduct from the water washing of crude biodiesel, wherein
optionally the compounds comprise soapstock, monoglycerides,
diglycerides, triglycerides and/or fatty acid alkyl esters or any
combination thereof.
[0046] In alternative embodiments, the method is a batch or a
continuous process.
[0047] In alternative embodiments, the heating and pressurizing the
mixed lipid feedstock takes place in conditions comprising:
temperature in a range of between about 100.degree. C. to
500.degree. C., or 200.degree. C. to 400.degree. C., or 240.degree.
C. to 300.degree. C., or at about 260.degree. C.; and/or a pressure
of between about 650 and 750 psig, between about 750 and 850 psig,
between about 850 and 1000 psig, between about 1000 and 1500 psig,
or between about 1500 psig and 1800 psig; and/or for between about
20 and 30 minutes, or between about 160 and 180 minutes, or between
about 300 minutes and 500 minutes.
[0048] In alternative embodiments, the amount of gas is sufficient
to increase the pressure of the reaction mixture, optionally in a
reaction vessel, in which the acidulation reaction is being carried
out to between about 10 and 1000 psig, about 20 to about 600 psig,
about 30 to about 500 psig, about 40 to about 400 psig, about 50 to
about 300 psig, about 60 to about 200 psig, about 60 to about 150
psig, about 70 to about 140 psig, about 80 to about 120 psig, about
90 to about 110 psig, or about 100 psig.
[0049] In alternative embodiments, the acidulation reaction is
carried out at a temperature in the range of between about
5.degree. C. to about 400.degree. C., e.g. about 10.degree. C. to
about 90.degree. C., about 15.degree. C. to about 70.degree. C.,
about 20.degree. C. to about 60.degree. C., or about 25.degree. C.
to about 40.degree. C.
[0050] In alternative embodiments, the acid or acid solution
comprises an organic and/or an inorganic acid (a mineral acid), a
hydrochloric acid, a sulfuric acid, a formic acid or sodium
bisulfate, and optionally when a stack gas comprising N.sub.2O, NO
(optionally NO.sub.2), SO.sub.x (optionally SO.sub.2), or H.sub.2S
is used the N.sub.2O, NO.sub.x, SO.sub.x, or H.sub.2S reacts with
water in the acidulation reaction mixture to form equivalent
aqueous acid species.
[0051] In alternative embodiments, after a reaction vessel has
reached a desired temperature and pressure to carry out the
acidulation step, the resulting reaction mixture is agitated, or
otherwise mixed in order to maximize the contacting of the soaps
with the acid, optionally carbonic acid, and optionally the mixture
can be agitated using a spinning blade mixer, and optionally the
mixture is agitated for between about 10 minutes to about 200
minutes, e.g. between about 25 minutes to about 150 minutes, or
between about 20 minutes to about 60 minutes, or about 30
minutes.
[0052] In alternative embodiments, after the acidulation reaction,
and optionally following an agitation step, the contents of the
acidulation reaction, optionally in a reaction vessel, are allowed
to settle or partition allowing for the formation (separation) of a
lipid layer and aqueous layer, wherein the lipid layer floats on
the top of the aqueous layer, and optionally the lipid layer
comprises free fatty acids and any non-acidulated soaps, and the
aqueous layer comprises water, glycerol, phosphate salts, sodium
bicarbonate, sodium carbonate or other equivalent salts,
unsaponifiable material (optionally waxes and sterols), and
dissolved carbonic acid.
[0053] In alternative embodiments, before or after the reaction
products of the acidulation reaction, optionally in a reaction
vessel, are allowed to settle or partition, the reaction products
of the acidulation step are transferred to a separation vessel,
optionally a decanter, a settler or an equivalent, or a centrifuge
where a lipid phase or component or separates or partitions out
from an aqueous phase or component; or, the acidulation product
mixture is not transferred to a separate vessel in order to
separate lipids (the lipid phase or component) from reaction
products in an aqueous phase or component, and after the lipid
phase or component or separates or partitions out from the aqueous
phase or component the aqueous layer is drained from the bottom of
the reaction vessel and the lipid layer (the lipid phase or
component) is recovered as the reaction product.
[0054] In alternative embodiments, methods and processes can
further comprise multiple acidulation reactions, optionally between
about 1 and 20 additional acidulation reactions, or about 1, 2, 3,
4, 5, 6, 7 or 8 or more additional acidulation reactions.
[0055] The method of any of the preceding claims, wherein after the
acidulation reaction the reaction vessel is depressurized, allowing
for dissolved carbonic acid or other gaseous acid to separate out
of the solution as gaseous CO.sub.2, or equivalents, and optionally
captured CO.sub.2 is recycled for use in the further acidulation
reactions.
[0056] In alternative embodiments, the solvent added to the thermal
hydrolysis reaction is a polar (optionally a methanol) or a
non-polar (optionally a hexane) solvent.
[0057] In alternative embodiments, the thermal hydrolysis reaction
and the acidulation reaction take place sequentially; or, the
thermal hydrolysis reaction and the acidulation reaction can take
place simultaneously as a "one pot" reaction in one reaction
vessel.
[0058] In alternative embodiments, the lipid phase or component,
optionally comprising unreacted soaps, is transferred to an
electrolysis unit (optionally a hydrogen evolving cathode (HEC)
electrolysis unit) wherein the lipid phase is reacted with an
anolyte (optionally the anolyte comprises a sodium or potassium
sulfate, a sodium or potassium nitrate, or a sodium or potassium
chloride) such that the unreacted soaps generate free fatty acids,
and optionally the electrolysis step converts substantially all, or
about 90%, 95%, 98% or more of the unreacted soaps to free fatty
acids, wherein optionally the anode comprises a mixed metal oxide
(MMO) layer coated onto a stable metal substrate, optionally a
titanium.
[0059] In alternative embodiments, the lipid phase or component is
transferred to an electrolysis unit (optionally a hydrogen evolving
cathode (HEC) electrolysis unit) comprising a vessel or suitable
container comprising an anode (e.g., an anode vessel) and a vessel
or other suitable container comprising a cathode (an cathode
vessel) separated by a selective filtration membrane, optionally a
polytetrafluoroethylene (PTFE) membrane, wherein optionally the
anode comprises a mixed metal oxide (MMO) layer coated onto a
stable metal substrate, optionally a titanium, and optionally the
cathode comprises a titanium or a Monel alloy, or any substrate
that is stable in a reducing environment.
[0060] In alternative embodiments, the aqueous phase or component,
or multiple aqueous phases if collected from multiple acidulation
reactions, is treated to remove water, wherein optionally the
treatment of the aqueous phase or component to remove water is by a
drying method, optionally evaporation via falling film, forced
recirculation flashing or equivalent, thereby generating a product
comprising sodium bicarbonate, and optionally the product is dried
further to generate a sodium bicarbonate product that is
substantially free of any water, optionally less than about 20%
water or less than about 10% water, and optionally the drying is
done using a fluidized bed dryer, a lyophilizer, a spray dryer, or
a rotary drum dryer.
[0061] In alternative embodiments, the aqueous phase or component,
or multiple aqueous phases if collected from multiple acidulation
reactions, is treated using a filtration, optionally a membrane
filtration system, a nano- or microfiltration system or a
size-exclusion filtration system, and optionally the filtration is
operationally in-line operating continuously with the acidulation
step such that aqueous phase generated in the acidulation reaction
(or each acidulation reaction if more than one acidulation
reaction) is treated immediately after or during the point at which
the aqueous phase is separated from the lipid phase, and optionally
the aqueous phase is collected and treated in a single batch.
[0062] In alternative embodiments, soaps and/or other saponifiable
material rejected by the filtration (optionally, soaps and/or other
saponifiable material that do not pass through a membrane of a
filter system) are returned to the lipid phase for subsequent
acidulation reactions, thereby increasing the overall fatty acid
yield.
[0063] In alternative embodiments, the aqueous phase or component,
or multiple aqueous phases if collected from multiple acidulation
reactions, is treated with calcium hydroxide (optionally slaked
lime) to form a calcium precipitate, optionally a calcium phosphate
(Ca.sub.x(PO.sub.4).sub.x) precipitate. In alternative embodiments,
the lime-treated aqueous phase or component, or multiple aqueous
phases if collected from multiple acidulation reactions, is
subjected to an oxidation step, optionally a Fenton oxidation
wherein hydrogen peroxide and Fe.sup.2+ ions are used to catalyze
OH radical formation.
[0064] In alternative embodiments, the aqueous phase or component,
or multiple aqueous phases if collected from multiple acidulation
reactions, is subjected to electrolysis to recover monovalent ions
as a base for a value added product, wherein electrical current is
passed through a cathode, the water is reduced, thereby generating
hydroxide ions; and as monovalent ions (optionally sodium or
potassium) are pushed across a membrane (separating an anode vessel
from a cathode vessel) into the cathode vessel, they react with the
generated hydroxide ions to generate a corresponding hydroxide base
(optionally a sodium hydroxide or a potassium hydroxide), and
optionally the hydroxide base separated out, recovered and/or
isolated.
[0065] The foregoing has outlined rather broadly the more pertinent
and important features of the present invention in order that the
detailed description of the invention that follows may be better
understood so that the present contribution to the art can be more
fully appreciated. Additional features of the invention will be
described hereinafter which form the subject of the claims of the
invention. It should be appreciated by those skilled in the art
that the conception and the specific embodiment disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present
invention. It should also be realized by those skilled in the art
that such equivalent constructions do not depart from the spirit
and scope of the invention as set forth in the appended claims.
[0066] All publications, patents, patent applications cited herein
are hereby expressly incorporated by reference for all
purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0067] The drawings set forth herein are illustrative of exemplary
embodiments provided herein and are not meant to limit the scope of
the invention as encompassed by the claims.
[0068] FIG. 1 is a flow diagram of an exemplary method as provided
herein comprising generating free fatty acids from a mixed lipid
feedstock comprising soaps, saponifiable material or equivalents
thereof comprising use of thermal hydrolysis followed by
acidulation with CO.sub.2.
[0069] FIG. 2 is a flow diagram of an exemplary method as provided
herein comprising generating free fatty acids from a mixed lipid
feedstock comprising soaps, saponifiable material or equivalents
thereof comprising use of thermal hydrolysis followed by
electrolysis.
[0070] FIG. 3 is a flow diagram of an exemplary method as provided
herein comprising generating free fatty acids from a mixed lipid
feedstock comprising soaps, saponifiable material or equivalents
thereof comprising the use of thermal hydrolysis, followed by
acidulation with CO.sub.2. and then electrolysis.
[0071] FIG. 4 is a flow diagram of an exemplary method as provided
herein comprising generating free fatty acids from a mixed lipid
feedstock comprising soaps, saponifiable material or equivalents
thereof, the method comprising the use of acidulation with an
organic and/or mineral acid prior to thermal hydrolysis; thermal
hydrolysis is performed followed by acidulation with the mineral
and/or organic acid.
[0072] Like reference symbols in the various drawings indicate like
elements.
[0073] Reference will now be made in detail to various exemplary
embodiments of the invention. The following detailed description is
provided to give the reader a better understanding of certain
details of aspects and embodiments of the invention, and should not
be interpreted as a limitation on the scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0074] In alternative embodiments, provided are methods, systems
and processes for the preparation of fatty acids and optionally
fatty acid derivatives, e.g. fatty acid alkyl esters, from mixed
lipid feedstocks comprising saponifiable material or any
triglyceride comprising material, including byproduct streams of
natural oil processing e.g. soapstocks, gums, or mixtures thereof.
In alternative embodiments, the feedstock comprises soapstock
obtained from the alkaline neutralization of a crude natural oil.
In alternative embodiments, the feedstock comprises the gums
product (comprising primarily phospholipids) generated during the
degumming of a natural oil. In alternative embodiments, the
feedstock comprises a mixture of product streams generated during
the processing of a crude natural oil and comprises soaps as well
as saponifiable lipids, e.g. phospholipids. glycerides, e.g. mono-,
di-, and/or triglycerides, or any combination thereof.
[0075] In alternate embodiments, the mixed lipid feedstock
comprises a mixture of soapstock and monoglycerides produced as a
byproduct from the water washing of crude biodiesel.
[0076] In alternative embodiments, processes and methods as
provided herein are more economical and efficient than currently
used approaches for the treatment of natural oil processing
byproducts, e.g., soapstocks and gums, to generate fatty acids,
fatty acid derivatives, or other value-added products.
[0077] In alternative embodiments, a mixed lipid feedstock, e.g. a
soapstock comprising soaps as well as saponifiable material (e.g.
glycerides and/or phospholipids) is reacted by thermal hydrolysis,
thereby generating a product in which substantially all of the free
fatty acids are cleaved from their respective glycerol backbones or
phosphate groups. The soaps present in the product stream generated
in foregoing the saponification step are then separated and reacted
with an acid in the acidulation step of the process, in which
optionally substantially all of the soaps are acidulated to form
free fatty acids.
[0078] In alternative embodiments, the mixed lipid feedstock
comprises crude (unrefined) natural oils, including plant- and
animal-derived oils, which are comprised primarily of
triacylglycerols (i.e. triglycerides), as well as smaller portions
of various lipids including mono- and diacyl-glycerols, (i.e.
mono-glycerides and di-glycerides, respectively), free fatty acids,
phospholipids, waxes, and other non-lipid components including, for
example, ketones, aldehydes, and hydrocarbons.
[0079] In alternative embodiments, prior to sale for human
consumption or for further processing, a crude natural oil is
refined to remove the majority of the non-triglyceride components.
The majority of natural oils can be refined using a chemical
refining process. In the first stage of the chemical refining
process, referred to as "degumming", crude oils are first washed
with water to remove the hydratable phospholipids (gums). The
resulting product stream separated from the oil during the
degumming step is referred to as "gums." Second, the degummed oils
are subjected to a neutralization step in which the degummed oil is
treated with a strong base, e.g. sodium hydroxide. During the
neutralization step, free fatty acids present in the oil react with
the base to form soaps (salts of fatty acids). In alternative
embodiments an additional processing step between the degumming and
neutralization step is used in which a small amount of a mineral
acid, e.g. phosphoric acid or citric acid, is added to the degummed
oil to convert any non-hydratable phospholipids into hydrated
phospholipids. After the neutralization step, the oil is washed to
remove the soaps and, if the oil was treated with a mineral acid,
the hydrated phospholipids. The resulting product stream separated
from the oil during the neutralization step is referred to as
"soapstock." If the oil is to be sold for human consumption, the
degummed, neutralized oil is then subjected to further processing
including, e.g. bleaching and deodorization steps.
[0080] Alternatively, in the production of biodiesel used to
practice methods provided herein, a lipid mixture is generated as a
byproduct. In the production of biodiesel, fatty acids are
esterified by several means including by enzymatic reaction,
acid/base reactions, supercritical alcohol, and/or ultrasonically.
The reaction generates water, which in turn back reacts with the
esters to generate monoglycerides and free fatty acids. The removal
of these impurities is achieved by water and/or base washing the
crude biodiesel. The washing generates a lipid mixture product of
soap, water, and/or monoglycerides, which is regarded as a waste
stream in the process of biodiesel refining. This subsequent
soapstock can be utilized in the thermal hydrolysis process
provided herein producing high yield free fatty acids as a value
added product for the biodiesel processors.
[0081] In alternative embodiments, the configuration of the
refinery varies, and soapstock and gums can be either stored
separately or combined into a single storage container. In
alternative embodiments, a "mixed lipid feedstock" refers to any
material or composition comprising soaps as well saponifiable
material, i.e. lipids capable of reacting to produce soaps (salts
of fatty acids). Saponifiable material in the mixed lipid feedstock
can include, without limitation, glycerides, e.g. mono-glycerides,
di-glycerides, or triglycerides, or a combination thereof, and/or
phospholipids. In alternative embodiments, the mixed lipid
feedstock is a soapstock. In alternative embodiments, the mixed
lipid feedstock comprises soaps and saponifiable lipids e.g.
glycerides and/or phospholipids. In alternative embodiments, the
mixed lipid feedstock is a mixture of soapstocks, comprising soaps,
saponifiable material, e.g. glycerides and/or phospholipids,
obtained during the processing of a natural oil. In alternative
embodiments, the mixed lipid feedstock is a soapstock washwater
obtained from the processing of a crude natural oil following the
neutralization step in the chemical refining process. In such
embodiments, the washwater can comprise water and soapstock,
wherein the soapstock comprises soaps, glycerides, phospholipids,
free fatty acids, and unsaponifiable material e.g. waxes and/or
sterols. In alternative embodiments, the soapstock washwater can
comprise between about 1% soapstock to about 100% soapstock, e.g.
between about 2% and 80% soapstock, about 3% and 70% soapstock,
about 4% and about 60% soapstock, about 5% and about 50% soapstock,
about 6% and about 40% soapstock, about 7% and about 30% soapstock,
about 8% and about 20% soapstock, about 9% and about 15% soapstock,
or between about 20% and about 12% soapstock, the remaining portion
of the soapstock washwater comprising water.
[0082] In alternative embodiments, the composition of the soapstock
used as a mixed lipid feedstock can vary depending on the crude
natural oil from which it was derived. Table 1 shows the
composition of various soapstocks used to practice methods and
processes as provided herein, e.g., as described in U.S. Pat. No.
4,118,407.
TABLE-US-00001 TABLE 1 Composition of soapstocks from the refining
of various natural oils Composition Soybean Cottonseed Coconut Palm
Kernel Palm Water 57.3 58.6 66.8 57.8 66.4 Neutral Oil 14.6 13.0
17.4 26.2 8.4 FFA 1.46 0.94 0.55 0.24 1.25 Unsaponifiable 1.1 1.4
0.85 0.38 0.2 Soap 14.2 17.5 14.4 14.2 23.8 Phosphatide 11.34 8.56
0 0 0 Phosphorus 0.8 0.38 0.16 0 0 Total FFA 23.7 27.6 27.3 38.1
21.9 pH 9.5 9.5 9.2 9.2 10.8
[0083] Other mixed lipid feedstocks suitable for use in methods and
processes as provided herein comprises tall oil soaps. Tall oil
soaps are generated via the alkaline pulping of wood in the Kraft
process. The alkaline pulping of wood using the Kraft process
results in the production of black liquor, comprising the majority
of the non-cellulose components of the wood. These products include
hemicelluloses, lignin, and various salts of carboxylic acids
including rosin salts and soaps (salts of fatty acids). After the
black liquor is concentrated using multiple effect evaporators, it
is allowed to settle or is centrifuged. As the concentrated black
liquor settles, the soaps float to the surface where they are
skimmed and removed. The skimmed product (referred to as black
liquor soaps or tall oil soaps) can be used as a feedstock in
various embodiments of processes and methods as provided
herein.
[0084] In alternative embodiments, the mixed lipid feedstock used
to practice methods and processes as provided herein comprises a
saponified crude natural oil, e.g. a saponified vegetable oil. In
alternative embodiments, the mixed lipid feed feedstock is a
saponified castor oil, i.e. a composition comprising soaps derived
from mixing a base with a castor oil, the saponifiable content in
the castor oil, e.g. glycerides, and phospholipids, having been
converted to soaps. The majority of the fatty acid content in
castor oil (e.g. between 80 to about 95% of the fatty acid content)
is ricinoleic acid (12-hydroxy-9-cis-octadecenoic acid). In
alternative embodiments, provided are methods or processes for
generating ricinoleic acid by thermal hydrolysis, acidulating the
saponified castor oil to generate free fatty acids, and then
separating or isolating ricinoleic acid from the generated free
fatty acids.
[0085] Alternative embodiments of the methods and processes are
described in greater detail below.
Thermal Hydrolysis
[0086] In alternative embodiments, in thermal hydrolysis processes
as provided herein, the mixed lipid feedstock is hydrolyzed and the
reaction is driven by heat and pressure. The reaction mechanism
includes the hydroxyl ion attacking the carbonyl group(s), or
ester(s), present in mixed lipid feedstocks in the form of
triglycerides, and/or phospholipids. When full reaction proceeds,
the process yields fatty acids, glycerol, and other non-TFA solids
due to the inherent nature of soapstock.
[0087] In alternative embodiments, the first stage of the process
is a thermal hydrolysis reaction with a mixed lipid feedstock. In
alternative embodiments, the thermal hydrolysis reaction can take
place in any suitable reaction vessel known in the art. In
alternative embodiments, the reaction can be a batch or continuous
process, depending on the desired throughput of material from the
reaction. In alternative embodiments, the process involves adding a
mixed lipid feedstock to a reactor where thermal hydrolysis will
occur.
[0088] In alternative embodiments, the thermal hydrolysis reaction
is carried out at a temperature in the range of between about
20.degree. C. to about 600.degree. C., or in a range of between
about 100.degree. C. to 500.degree. C., or about 200.degree. C. to
400.degree. C., or about 240.degree. C. to 300.degree. C., or at
about 260.degree. C. In alternative embodiments, the thermal
hydrolysis reaction is carried out at a pressure of between about
500 to 2000 psig, between about 650 and 750 psig, between about 750
and 850 psig, between about 850 and 1000 psig, between about 1000
and 1500 psig, or between about 1500 psig and 1800 psig. In
alternative embodiments, the thermal hydrolysis reaction is carried
out at ambient pressure. In alternative embodiments, the time
allotted for the reaction to occur is between about 1 minute and
300 minutes, e.g. between about 20 and 30 minutes, or between about
160 and 180 minutes, or between about 300 minutes and 500 minutes.
In alternative embodiments, the amount of water in the thermal
hydrolysis reaction is between about 2:1 water-to-total dissolved
solids (TDS) present in the feedstock to about 15:1, e.g. about
10:1.
Acidulation of Soaps:
[0089] In alternative embodiments, the fatty acids, or the reaction
product generated during the thermal hydrolysis step of the process
is subjected to an acidulation step in which most, or substantially
all, of the remaining soaps are acidulated to generate free fatty
acids. The soaps are acidulated by mixing them, in any suitable
reaction vessel, e.g. the same reaction vessel that was used in the
thermal hydrolysis step, with an acid to form an acidulation
reaction mixture.
[0090] In alternative embodiments, the acid is either an organic or
inorganic acid, e.g. carbonic acid. In alternative embodiments,
carbonic acid is generated by mixing CO.sub.2 with the thermal
hydrolysis reaction product, wherein the CO.sub.2 reacts with the
water (present in the thermal hydrolysis reaction product) to form
carbonic acid. In alternative embodiments, the CO.sub.2 is a liquid
or a gas or a combination thereof. In an exemplary embodiment, when
the CO.sub.2 is a gas, the CO.sub.2 is then piped or otherwise
directed into the reaction vessel wherein the CO.sub.2 reacts with
the water present in the thermal hydrolysis reaction product to
form carbonic acid. Once formed, the carbonic acid reacts with the
soaps, thereby acidulating them and generating free fatty acids and
a corresponding salt, e.g. sodium bicarbonate.
[0091] The amount of CO.sub.2 used in the acidulation step of
alternative embodiments of the process can vary depending on, for
example, ambient temperature and pressure conditions, but is
generally sufficient to increase the pressure of the reaction
vessel in which the acidulation reaction is being carried out to
between about 0 and about 2000 psig, e.g. between about 10 and 1000
psig, about 20 to about 600 psig, about 30 to about 500 psig, about
40 to about 400 psig, about 50 to about 300 psig, about 60 to about
200 psig, about 60 to about 150 psig, about 70 to about 140 psig,
about 80 to about 120 psig, about 90 to about 110 psig, or about
100 psig. In alternative embodiments, the acidulation reaction is
carried out at a temperature in the range of between about
5.degree. C. to about 400.degree. C., e.g. about 10.degree. C. to
about 90.degree. C., about 15.degree. C. to about 70.degree. C.,
about 20.degree. C. to about 60.degree. C., or about 25.degree. C.
to about 40.degree. C.
[0092] In alternative embodiments, the source of the CO.sub.2 used
in the acidulation step is a "stack gas" or "flue gas" (used
interchangeably herein and referred to as "stack gas") other source
of gaseous CO.sub.2 emitted from an industrial process or any oven,
furnace, boiler, steam generator or the like, e.g. from a coal
fired power plant, ethanol plant, brewery, or any other industrial
process wherein a gaseous waste stream comprising CO.sub.2 is
emitted.
[0093] In alternative embodiments, the stack gas is piped or
otherwise transferred from the emission source to the vessel in
which the acidulation reaction is carried out. In alternative
embodiments, the stack gas can comprise gaseous CO.sub.2 and
possibly other products depending on the filtration or other
purification steps that the stack gas was subjected to prior to
being transferred to the acidulation reactor. The exact composition
of the stack gas will vary depending on the emission source and
post-combustion processing steps but is generally comprised
primarily of CO.sub.2 (e.g. about 60% or more CO.sub.2),
nitrogenous products (e.g. N.sub.2O and NO.sub.2), sulfur dioxide
(SO.sub.2), hydrogen sulfide (H.sub.2S), water vapor and possibly
other products.
[0094] In alternative embodiments wherein a stack gas is used as
the CO.sub.2 source, other products in the stack gas, e.g.
N.sub.2O, NO.sub.2, SO.sub.2, H.sub.2S or the like can react with
the water in the acidulation reaction mixture to form their
equivalent aqueous acid species (e.g., SO.sub.2 would react with
the water to generate sulfuric acid). The generation of additional
acid products in the reaction mixture can serve to increase the
reaction efficiency and reduce the total amount of time required to
perform the acidulation reaction. As such, the use of a stack gas
"waste stream" may be beneficial in the process, representing an
opportunity to utilize a waste stream from one industrial process
to benefit another industrial process (which might otherwise
require expensive processing steps prior to being emitted) as an
input for the present process. The process therefore is a means of
diverting what would otherwise be an environmental pollutant to an
input stream of a separate industrial process.
[0095] In alternate embodiments, the CO.sub.2 can be liquid from a
bulk tank or truck. Other products may optionally be added to the
acidulation reaction mixture e.g. organic or inorganic acids, e.g.
formic acid or sodium bisulfate. The addition of additional acids
can be useful in tailoring the ash profile of the resulting
acidulation product mixture (the mixture of products resulting from
the acidulation reaction) such that certain end products can be
used as, e.g. a fertilizer. The optional addition of additional
acids can serve to increase the reaction efficiency by acidulating
soaps that were not acidulated by the carbonic acid.
[0096] In alternative embodiments, the desired pH of the
acidulation reaction mixture is less than about pH 5, or is between
about pH 1 to pH 6, or is about pH 1, 2, 3, 4, 5 or 6. In
alternative embodiments, the amount of CO.sub.2 and optional other
acids (e.g. from stack gas) added to the acidulation reaction
mixture is sufficient to reduce the pH of the mixture to below 5 or
about 2 or 3.
[0097] In alternative embodiments, flowing the addition of the
CO.sub.2 (or stack gas, or carbonated water) and optional other
acids to the saponification (thermal hydrolysis) reaction product
and after the reaction vessel has reached the desired temperature
and pressure to carry out the acidulation step, the resulting
reaction mixture is agitated, or otherwise mixed in order to
maximize the contacting of the soaps with the carbonic acid
(generated once CO.sub.2 reacts with the water present in the
saponification reaction mixture). The mixture can be agitated using
any suitable method known in the art, e.g. a spinning blade mixer.
In alternative embodiments, the mixture is agitated for between
about 10 minutes to about 200 minutes, e.g. between about 25
minutes to about 150 minutes, or between about 20 minutes to about
60 minutes, or about 30 minutes.
[0098] In alternative embodiments, following the agitation step,
the contents of the acidulation reaction vessel are allowed to
settle, allowing for the formation of a lipid layer and aqueous
layer. The lipid layer floats on the top of the aqueous layer. In
alternative embodiments, the lipid layer comprises free fatty acids
and any non-acidulated soaps, and the aqueous layer comprises, for
example, water, glycerol, phosphate salts, sodium bicarbonate,
smaller amounts of sodium carbonate (or other equivalent salts),
unsaponifiable material e.g. waxes and sterols, and dissolved
carbonic acid. In alternative embodiments, the lipid layer
comprising the free fatty acids generated in the acidulation
reaction is separated from the remaining reaction products. The
separation technique used can be any suitable separation technique
known in the art. In alternative embodiments, the reaction products
of the acidulation step are transferred to a separation vessel,
e.g. a decanter wherein the mixture is allowed to settle and
allowed to separate, forming an aqueous phase and a "lipid" phase
comprising the free fatty acids which floats on top of the aqueous
phase. In alternative embodiments, the decantation procedure
results in the formation of separate lipid and aqueous phases in
approximately 1 hour or less, depending on the configuration of the
reaction vessel. Other separation techniques, e.g. centrifugation,
may also be used in accordance with embodiments as provided herein.
In certain embodiments, the acidulation product mixture is not
transferred to a separate vessel in order to separate the lipids
from the remaining reaction products. In such embodiments, the
aqueous layer is drained from the bottom of the reaction vessel and
the lipid layer is recovered as the reaction product.
[0099] In alternative embodiments, the reaction products generated
during the acidulation reaction are transferred to the separation
unit in such a way that the loss of any gaseous CO.sub.2 is
minimized, e.g. via the use of a liquid level control feedback or
other suitable method.
[0100] In certain embodiments, after the acidulation reaction, the
reaction vessel is depressurized, allowing for the dissolved
carbonic acid to separate out of the solution as gaseous CO.sub.2.
In such embodiments, the captured CO.sub.2 is recycled for use in
the acidulation step.
[0101] In alternative embodiments, the process comprises multiple
acidulation reactions e.g. between about 1 and 20, or about 1, 2,
3, 4, 5, 6, 7, 8, or 9 or more acidulation reactions. In such
embodiments, following the first acidulation reaction as described
above, the reaction vessel is depressurized and the CO.sub.2 is
captured and recycled. The lipid layer is then separated or
otherwise removed from the aqueous layer, and water is added into
the reaction vessel containing the lipid layer. CO.sub.2 is then
added to the reaction vessel until the desired pressure is reached
as described above. The reaction vessel is then heated and agitated
as previously described and allowed to settle. The resulting lipid
layer is then separated or otherwise removed from the aqueous layer
as previously described. The resulting lipid layer is then
separated or otherwise removed and can optionally be subjected to
additional acidulation reactions as previously described, wherein
additional water and CO.sub.2 is added and the resulting mixture
agitated at the desired temperature and pressure and the resulting
lipid layer is separated or otherwise removed from the aqueous
layer. The number of acidulation reactions in the process can vary
depending on the desired free fatty acid yield and process
economics. In certain embodiments, the number of acidulation
reactions is sufficient to acidulate substantially all of the soaps
present in the thermal hydrolysis product mixture, e.g. lto 8
acidulation reactions, e.g. 2 acidulation reactions.
[0102] In alternate embodiments, following the first acidulation
reaction as described above, the reaction vessel is not
depressurized and the CO.sub.2 is allowed to remain in the pressure
vessel. Instead, the aqueous layer is subsequently drained from the
bottom of the reactor and recycled to be used in subsequent
acidulation reactions where the CO.sub.2 remains pressurized in the
vessel. In alternative embodiments, a salt, e.g. sodium chloride or
other equivalent salt, is added to the product mixture following an
acidulation reaction. The addition of NaCl or equivalent salt to
the acidulation reaction product increases the ionic strength of
the product mixture and prevents the lipid layer from emulsifying
with the aqueous layer. In certain embodiments, the process
comprises one or more acidulation reactions and the salt, e.g.
NaCl, is added to the product mixture generated by the first
acidulation reaction. In certain embodiments, the process comprises
two or more acidulation reactions, e.g. six acidulation reactions,
and the salt is added to the product mixture generated by the third
acidulation reaction.
[0103] The acidulation reaction, or multiple acidulation reactions,
can take place in any suitable reaction vessel known in the art. In
alternative embodiments, the reaction can be a batch or continuous
process, depending on the desired throughput of material from the
reaction. In embodiments of the process comprising multiple
acidulation reactions, the multiple acidulation reactions can take
place in the same reaction vessel or in separate reaction vessels.
In embodiments comprising multiple acidulation reactions taking
place in multiple reaction vessels, the lipid layer generated
during each acidulation reaction is separated or otherwise removed
from the corresponding aqueous layer and transferred to a separate
reaction vessel wherein the lipid layer is mixed with water and
CO.sub.2 and the resulting mixture is agitated for the desired
period under the desired temperature and pressure conditions and
allowed to settle in order to generate a new lipid layer.
[0104] In alternative embodiments, the separated free fatty acids
generated in the acidulation reaction are subjected to further
processing steps. In alternative embodiments, the free fatty acids
are further separated by their carbon chain length, i.e. the number
of carbon atoms contained in the aliphatic tail portion of the free
fatty acid, which can comprise, in alternative embodiments, between
4 and 28 carbon atoms. In alternative embodiments, the free fatty
acids are separated by their saturation. In alternative
embodiments, the saturated free fatty acids are separated from the
unsaturated free fatty acids. In alternative embodiments, the
separated free fatty acids are separated into short-chain fatty
acids (aliphatic tail length of fewer than 6 carbon atoms),
medium-chain fatty acids (aliphatic tail lengths of between 6 and
12 carbon atoms), long-chain fatty acids (aliphatic tail length of
between 13 and 21 carbon atoms), and very long-chain fatty acids
(aliphatic tail length of 22 or more carbon atoms). In alternative
embodiments, the separated free fatty acids are separated into
individual fatty acids streams based on the length (number of
carbon atoms) of their aliphatic tails.
[0105] In alternative embodiments, the separated free fatty acids
can be further separated into distinct cuts, based on their
aliphatic tail length and/or saturation, using any suitable
technique known in the art, e.g. ion exchange, continuous ion
exchange, chromatography, continuous chromatography or the
like.
[0106] In alternative embodiments, the thermal hydrolysis reaction
and the acidulation reaction take place sequentially; or, the
thermal hydrolysis reaction and the acidulation reaction can take
place simultaneously, e.g., as in a "one pot" reaction in one
reaction vessel.
Electrolysis of Lipid Phase from Acidulation Reaction:
[0107] In alternative embodiments, the lipid phase having been
separated in the foregoing acidulation reaction(s) comprises a
small percentage of unreacted soaps, for example, soaps that were
not acidulated to generate free fatty acids, e.g., between about 5
wt % and 30 wt %, or about 10 wt % of the lipid phase. In order to
increase the overall efficiency of the process, alternative
embodiments of the process comprise an electrolysis step wherein
the lipid phase comprising a small amount of unreacted soaps is
transferred to an electrolysis unit wherein the soaps in the lipid
are reacted with an anolyte to generate free fatty acids. In
alternative embodiments, the addition of the electrolysis step
converts substantially all, e.g., 90%, 95%, 98% or more of the
unreacted soaps to free fatty acids.
[0108] In alternative embodiments comprising the electrolysis step,
the lipid layer from the acidulation reaction(s) is transferred to
an electrolysis unit (e.g. a hydrogen evolving cathode (HEC)
electrolysis unit) comprising a vessel or suitable container
comprising an anode (the anode vessel) and a vessel or other
suitable container comprising a cathode (the cathode vessel)
separated by a selective filtration membrane, e.g. a
polytetrafluoroethylene (PTFE) membrane. In alternative
embodiments, the anode is comprised of a mixed metal oxide (MMO)
layer coated onto a stable metal substrate, e.g. titanium. In
alternative embodiments, the cathode can be, for example, titanium
or a Monel alloy (a nickel alloy primarily composed of nickel (up
to 67%) and copper), or any other substrate that is stable in a
reducing environment.
[0109] In alternative embodiments, a solution comprising an anolyte
is added to the anode vessel. In alternative embodiments the
anolyte is a sodium and/or potassium salt, e.g. sodium or potassium
sulfate (for illustrative purposes, sodium sulfate is the anolyte
in the remaining description of the electrolysis step, although
those skilled in the art would appreciate that an equivalent
anolyte such as potassium sulfate may be substituted in the
process). Simultaneously, the cathode vessel is filled with a
catholyte, e.g. sodium hydroxide. In alternative embodiments, a
current is passed through the electrolysis unit resulting in the
oxidation of the sodium sulfate, thereby generating sodium ions and
sodium bisulfate. The current also can serve to oxidize the water,
generating hydrogen ions. The generated sodium ions are pushed
across the electrolysis membrane and the generated sodium bisulfate
results in a reduction of the pH of the anolyte solution to, e.g.
about 3. Once the pH has reached a suitable level, e.g. about 3, a
portion of the separated lipid from the acidulation step can be
introduced into the vessel with the anolyte solution wherein any
unreacted soaps in the lipid layer react with the sodium bisulfate
to generate free fatty acids and sodium sulfate. The generated free
fatty acids can be separated from the anode vessel by any suitable
method in the art, e.g. through a pipe at the top of the anode
vessel and into separate side tank. The generated sodium sulfate
acts as the regenerated anolyte which, after the fatty acids have
been removed from the anode vessel, and can be oxidized by passing
a current through the anode. As such, the electrolysis unit
operates in a semi-continuous fashion, wherein sodium sulfate is
oxidized to generate sodium bisulfate, thereby lowering the pH of
the anolyte solution. In alternative embodiments, once the pH has
reached a suitable level, e.g. about 3 additional lipid material
from the acidulation reaction step is added, and the soaps present
in the lipid material react with the sodium bisulfate to generate
free fatty acids and sodium sulfate.
[0110] In alternative embodiments, as the electrical current is
passed through the cathode, the water is reduced, thereby
generating hydroxide ions. As the sodium ions are pushed across the
membrane from the anode vessel into the cathode vessel, they react
with the generated hydroxide ions to generate sodium hydroxide. In
alternative embodiments, the starting concentration of the
catholyte (sodium hydroxide) can be about 30 wt %. As additional
sodium hydroxide can be generated (from the sodium ions moving
across the membrane and into the cathode and reacting with the
hydroxide ions), the concentration of sodium hydroxide can be
increased to, e.g. about 33 wt %, before some of the sodium
hydroxide is removed to bring the concentration back down to its
original concentration, e.g. 30 wt %. The generated sodium
hydroxide solution comprising sodium hydroxide and water can be
recycled, or sold as a value added product.
[0111] In alternative embodiments, the electrolysis unit is a
hydrogen evolving cathode (HEC) unit with a current density in the
range of about 1-10 kA/m.sup.2. In alternative embodiments, the
voltage of the individual cells of the unit can be in the range of
between about 3 and 15 volts. In alternative embodiments, the unit
comprises holding tanks for the anolyte and catholyte for
electrolyte balancing as the process is carried out. In alternative
embodiments, the holding tank of the catholyte also serves as the
additional tank for the lipid product, as well as a decanter for
separating fatty acids generated in the process. In alternative
embodiments, upon startup of the electrolysis unit, the sodium
sulfate anolyte is electrolyzed, causing the pH of the anolyte
solution to drop from, e.g. about 7 to about 3 to 3.5, and the
temperature of the anode vessel is increased to between about 40 to
90.degree. C., or above the melting point of the lipid solution
entering the anode. In alternative embodiments, the lipid product
is added to the anolyte solution until the pH increases to, e.g.
about 4.5, after which point the addition of the lipid product is
halted. In alternative embodiments, once the anolyte is
electrolyzed, it contacts the soaps, which float in the holding
tank/decanter due to limited solubility in the anolyte. Once the pH
in the anolyte solution is reduced to 3-3.5, the circulating pump
halts and fatty acids can be decanted from the anolyte for
downstream processing.
[0112] In alternative embodiments, the foregoing electrolysis
procedure is used as a total replacement of the acidulation
reaction comprising acidulating soaps using carbonic acid. In such
embodiments, the thermal hydrolysis product mixture generated in
the thermal hydrolysis reaction is subjected to electrolysis as
described above, wherein the product entering the anode vessel of
the electrolysis unit is the thermal hydrolysis product mixture
rather than the lipid layer separated from the acidulation product
mixture.
Treatment of Aqueous Phase from Acidulation Reaction:
[0113] Evaporation/Drying
[0114] In alternative embodiments, the aqueous phase(s) generated
in the one or more acidulation reactions is subjected to one or
more processing steps in order to recover desirable reaction
products that remain in the aqueous phase of the acidulation
reaction products and/or to treat the aqueous phase such that the
resulting product meets or exceeds relevant regulatory standards
relating to animal feed additives.
[0115] In alternative embodiments, the aqueous phase, or multiple
aqueous phases (i.e. collected from acidulation reactions) is
treated to remove water, e.g. by any suitable drying method (e.g.
evaporation via falling film, forced recirculation flashing, or any
other suitable method) known in the art, thereby generating a
product comprising sodium bicarbonate. Care must be taken so as not
to convert sodium bicarbonate to sodium carbonate via thermal
degradation, so evaporation temperature should be conducted below
about 60.degree. C. and should be conducted under a vacuum.
[0116] In alternative embodiments, once a majority of the water has
been removed from the aqueous stream(s), the resulting product can
be dried further to generate a sodium bicarbonate product that is
substantially free of any water, e.g. less than about 20% water or
less than about 10% water. Suitable apparatuses for creating a
substantially dry sodium bicarbonate product include fluidized bed
dryers, lyophilizers, spray dryers, and rotary drum dryers. The
generated dried sodium bicarbonate product can be used in any
application that utilizes a crude sodium bicarbonate stream, e.g.
as an animal feed additive.
[0117] Filtration
[0118] In alternative embodiments, the aqueous phase(s) generated
in the one or more acidulation reactions is subjected to one or
more processing steps in order to recover desirable reaction
products that remain in the aqueous phase of the acidulation
reaction products and/or to treat the aqueous phase such that the
resulting product meets or exceeds relevant regulatory standards
relating to wastewater. In alternative embodiments, the aqueous
phase(s) generated during one or more acidulation reactions can
comprise various organic molecules and salts in addition to water.
The exact composition of the aqueous phase(s) will vary depending
on the feedstock used in the process, as well as other process
variables, e.g. the reaction conditions, separation technique to
separate the lipid phase from the aqueous phase during the
acidulation process, etc. In alternative embodiments, the aqueous
phase(s) may include, in addition to water: sodium bicarbonate (or
equivalent salt), glycerol, phosphates, cholines, ethanolamines,
sodium sulfate (or equivalent salt), inositol, unreacted
saponifiable material, e.g. soaps and/or glycerides, residual
(small amounts of) free fatty acids, other organic or inorganic
compounds, or any combination thereof.
[0119] The composition of an exemplary aqueous phase generated in
the acidulation step comprising 6 acidulation reactions, wherein
the feedstock of the process is a soapstock obtained from the
processing of a crude soybean oil, is described below:
TABLE-US-00002 Water 92.8% Sodium sulfate 1.4% Glycerin 0.79%
Choline 0.06% Ethanolamine 0.02% Inositol 0.05% Phosphate 0.12%
Sodium bicarbonate 4.72%
[0120] In alternative embodiments, the aqueous phase(s) may be
treated using filtration, e.g. a size-exclusion filtration system.
In alternative embodiments, the filtration step may be
operationally in-line (i.e. continuously) with the acidulation step
such that aqueous phase generated in each acidulation reaction (if
the embodiment comprises more than one acidulation reaction) is
treated immediately after or during the point at which the aqueous
phase is separated from the lipid phase. In other embodiments, the
aqueous phases may be collected and treated in a single batch.
[0121] In alternative embodiments, wherein the process comprises
multiple acidulation reactions, the aqueous phase generated in each
of the acidulation reactions is continuously pumped through a
filtration mechanism, e.g. a nano- or microfiltration system or
other appropriate membrane filtration system which may be selected
from any of the known nano-, micro- or other appropriate
size-exclusion filtration mechanisms or systems known in the art.
In alternative embodiments, the size of the pores of the filter
allows for the rejection (i.e. allows the particles to pass through
the membrane) of certain particles, e.g. soaps and/or phosphates,
and retains (i.e. does not allow the particles to pass through the
membrane) the sodium bicarbonate (or other equivalent salt). In
alternative embodiments, the particles that pass through the
membrane of the filter have a molecular weight less than the
molecular weight of sodium palmitate, e.g. sodium bicarbonate,
sodium phosphates, etc. In alternative embodiments, rejected
particles are sodium (or other equivalent) soaps, e.g. sodium
palmitate, sodium oleate, etc. In alternative embodiments, the
filtration system provides for a more efficient process in that the
soaps and/or other saponifiable material rejected by the membrane
of the filter are returned to the lipid phase for subsequent
acidulation reactions, thereby increasing the overall fatty acid
yield of the process.
[0122] In alternative embodiments, the addition of a filtration
step in the process serves to drive the acidulation reaction to
completion by removing the sodium bicarbonate (or other equivalent
salt) from the acidulation product. Sodium bicarbonate can
"back-react" with the fatty acids generated in the acidulation
step, wherein some of the fatty acids react with the sodium
bicarbonate to generate soaps, thereby lowering the overall fatty
acid yield of the process. By removing the generated sodium
bicarbonate from the acidulation products, the opportunity for
back-reacting with the sodium bicarbonate is diminished and the
fatty acid yield of the process is increased.
[0123] In alternative embodiments, the filtration step is carried
out in a pH range of between about 6 and 11 and a pressure of
between about 50 and 800 psi, while maintaining a temperature of
between about 23 and 100.degree. C. In alternative embodiments, the
pH of the acidulation product solution on which the filtration step
is carried out varies depending on the amount of sodium bicarbonate
in the solution. As the sodium bicarbonate is removed, e.g. via
filtration, the pH drops and becomes increasingly acidic, thereby
driving the acidulation reaction to completion. In alternative
embodiments, the aqueous phase of the acidulation reaction(s) is
pumped through the filter at a range of between about 1 and 100
gallons per minute. In alternative embodiments, the size of the
pores in the filter membrane has a molecular weight cutoff (MWCO)
of between about 100-250 Daltons.
[0124] In alternative embodiments, the retained portion of the
aqueous phase comprising the sodium bicarbonate (or other
equivalent salt if sodium hydroxide was not used in the
saponification reaction step) is then subjected to a concentration
step using, for example, reverse osmosis (RO). In alternative
embodiments, the conditions for the RO step are similar to those of
the filtration step, i.e. a pH in the range of between about pH 6
and pH 11, a pressure of between about 50 psi and 800 psi, while
maintaining a temperature of between about 23.degree. C. and
100.degree. C. In alternative embodiments, the concentrated sodium
hydroxide can be discarded or sold, increasing the overall
efficiency of the process. In alternative embodiments, the water
produced in the RO step is suitably pure to be recycled within the
acidulation step, thereby increasing the efficiency of the process
and reducing total water consumption.
[0125] Lime Treatment and Oxidation of Organics
[0126] In alternative embodiments, the aqueous phase generated in
the acidulation reaction, or multiple acidulation reactions, is
collected and contacted with calcium hydroxide, i.e. slaked lime.
The amount of lime added to the aqueous phase is generally an
amount sufficient to increase the pH of the solution to about 11.
The lime-treated aqueous phase is allowed to react for a period of
between about 1 and 24 hours. During the reaction time, various
precipitates form and the pH of the solution increases to about 12
or 13.
[0127] In the same lime-contacting step described above, various
calcium precipitates are formed when they react with various
components in the aqueous phase. These precipitates can include,
for example, various calcium phosphates (i.e.
Ca.sub.x(PO.sub.4).sub.x). Other components of the lime-treated
aqueous phase can include, for example, those products that were
present in the recovered aqueous phase of the one or more
acidulation reactions that did not react with the lime, e.g.
glycerol, ethanolamines, choline, other organics, or any
combination thereof.
[0128] In order to satisfy the Biochemical Oxygen Demand
requirements for conventional wastewater treatment facilities, in
alternative embodiments, the lime-treated aqueous phase product may
be subjected to an oxidation step in which the organics present in
the solution, e.g. phosphorous, glycerin, and other organics are
fully oxidized into gaseous products that precipitate out of
solution. In alternative embodiments, the lime-treated aqueous
phase is subjected to Fenton oxidation wherein hydrogen peroxide
and Fe.sup.2+ ions are used to catalyze OH radical formation. In
alternative embodiments, the Fenton oxidation step is carried out
by adding between about 1 and 10 grams of hydrogen peroxide per
liter of aqueous phase liquid and between about 0.1 and 1.0 mol
Fe.sup.2+ per mol of hydrogen peroxide to the lime-treated aqueous
phase. The resulting mixture is then allowed to react for between
about 1 and 24 hours at a temperature of between about
20-50.degree. C. Once the hydrogen peroxide and Fe.sup.2+ are added
to the lime-treated aqueous phase, the pH will drop rapidly to
between about 3 and 9, e.g. less than pH 7. The pH then rises
slowly as the organics are gasified and leaves the solution. The
reaction is considered complete when the rate of change in the pH
of the solution is less than about 0.1 units/hour. UV oxidation can
optionally be used in combination with Fenton oxidation.
[0129] In alternative embodiments, following the oxidation step,
the solution is then contacted with fresh lime to precipitate any
unbound phosphorus and other acidic species. The conditions for the
second lime treatment step are identical to those of the first lime
treatment step.
Electrolysis of Aqueous Phase
[0130] In alternative embodiments, the aqueous phase is subject to
electrolysis to recover monovalent ions as a base for a value added
product. In alternative embodiments, as the electrical current is
passed through the cathode, the water is reduced, thereby
generating hydroxide ions. As the monovalent ions, e.g. sodium or
potassium, are pushed across the membrane from the anode vessel
into the cathode vessel, they react with the generated hydroxide
ions to generate the corresponding hydroxide base, e.g. sodium
hydroxide or potassium hydroxide, which can be recovered and sold
as a value added product.
[0131] The invention will be further described with reference to
the examples described herein; however, it is to be understood that
the invention and embodiments as provided herein are not limited to
such examples.
EXAMPLES
Example 1: Thermal Hydrolysis and Acidulation of Mixed Lipid
Feedstock
[0132] This Example Describes an Exemplary Protocol of the
Invention:
[0133] A mixed lipid feedstock comprised of soapstock, glycerides,
and phospholipids was obtained from an oil refining facility. The
mixed lipid feedstock was added to a vessel and subject to thermal
hydrolysis to free the fatty acids from their glycerol backbones
and phosphate groups. The lipid product resulting from the thermal
hydrolysis reaction was then subjected to a first acidulation
reaction wherein CO.sub.2 was introduced into the reaction vessel
comprising the lipid product. The CO.sub.2 reacted with the water
in the lipid product to form carbonic acid and acidulated soaps,
thereby generating an acidulation reaction product comprising a
first lipid layer of free fatty acids and an aqueous layer
comprising water glycerol, sodium bicarbonate, unsaponifiable
material, e.g. waxes and sterols, dissolved carbonic acid, and
phosphate salts.
Feedstock Description:
[0134] The feedstock used in the present example was a mixed
soapstock obtained from a natural oil refinery. Water was added to
the mixed feedstock to ensure a ratio of 5:1 water-to-total
dissolved solids (TDS), or water:TDS. The mixture was then added to
an autoclave (e.g., a Parr) reactor where thermal hydrolysis was
performed. The total mass added to the 2 L autoclave (e.g., Parr)
reactor was 1.4 kg of feedstock material and water.
Composition of Feedstock:
[0135] 55 gallons soy soapstock (Archer Daniels Midland, Chicago,
Ill.); Makeup: 24.7 wt % TDS (Soaps, saponifiable material, and
unsaponifiable material), 15.9 wt % free fatty acids (64% dry TFA
based on TDS) and 46.14 wt % water.
Thermal Hydrolysis Reaction:
[0136] Thermal Hydrolysis Reaction:
[0137] Nitrogen gas was used to purge the reactor of air once the
feedstock was added. This was repeated 5 times to guarantee the air
had been purged from the reactor. The reactor temperature was set
to 270.degree. C. which allowed thermal hydrolysis to occur.
Agitation was set to approximately 60 rpm to allow minimal
movement. The temperature was held at 270.degree. C. for 30
minutes. The reactor was then allowed to cool to 90.degree. C. and
a post-thermal hydrolysis sample was acquired from the bottom of
the reactor.
Acidulation Reaction:
[0138] Acidulation Reaction:
[0139] After the thermal hydrolysis reaction, CO.sub.2 was slowly
introduced, e.g., over a period of about 8, 9 or 10 minutes or
more, into the sealed reaction vessel through a port located near
the bottom of the vessel. CO.sub.2 was continually added to the
reaction vessel until the pressure inside the vessel reached 300
psig. The reaction vessel was maintained at a temperature of
90.degree. C. and agitated using a spinning blade mixer spinning at
400 rpms for a period of 30 minutes. After 30 minutes, the contents
of the reaction vessel were allowed to settle for 10 minutes.
During settling, a lipid layer and an aqueous layer formed and the
lipid layer floated on top of the aqueous layer. The aqueous layer
was drained from the bottom of the reaction vessel.
[0140] Second Acidulation Reaction:
[0141] After the aqueous layer was removed following the first
acidulation reaction, the reaction vessel was not depressurized.
The contents in the reaction vessel were agitated using the
spinning blade mixer as 95 parts fresh water (based on 100 parts of
the first aqueous fraction) was simultaneously introduced through
the top of the reaction vessel. The reaction vessel was maintained
at a temperature of 90.degree. C. and agitated using the spinning
blade mixer at 400 rpms for a period of 30 minutes. After 30
minutes, the contents of the reaction vessel were allowed to settle
for 10 minutes. During settling, a lipid layer and an aqueous layer
formed and the lipid layer floated on top of the aqueous layer. The
aqueous layer was drained from the bottom of the reaction
vessel.
Analysis of FFA Content and FFA Profile:
[0142] Following the second acidulation reaction, a sample of the
hexane layer comprising the free fatty acids (FFAs) was removed
from the reaction vessel for analysis. First, the hexane was
removed from the sample. Using acid titration, it was determined
that the fatty acid content of the sample was 91 wt % FFA
(normalized based on FFA & soap). The remainder of the sample
was comprised of soaps and various unsaponifiable material. The
fatty acid profile of the sample is shown is Table 2.
TABLE-US-00003 TABLE 2 Fatty acid profile of sample C16 C18 Other
FFAs Monos, di-acids, etc. 19% 79% <1% .ltoreq.1%
Example 2: Electrolysis of Lipid Phase from Acidulation
Reaction
[0143] Materials:
[0144] Two one liter working solutions in 2 L glass beakers with
stirbars on 1000 W hotplates being recirculated by constant flow
rate peristaltic pumps @ 60.degree. C. (anolyte is saturated
aqueous sodium sulfate and catholyte is 10 wt % sodium hydroxide);
5 cm.sup.2 NAFION 115TH membrane, PVC body and tubing,
6''.times.1'' DSA, 6''.times.1'' Monel 400 cathode.
[0145] Using 0-30 V 0-20 A DC power supply, turn power supply on to
provide constant amperage of 3 A to electrodes in PVC system. Pump
anolyte and catholyte around with their respective peristaltic
pumps at 750 mL/min and heat both to 60.degree. C. Reduce anolyte
(side with Na.sub.2SO.sub.4 solution) pH to about 3 to 3.5 before
slowly adding enough saponified soapstock to increase pH of anolyte
to 5. Stop addition of saponified soapstock and allow
electrochemical cell to reduce anolyte pH back to about 3 to 3.5
before adding more saponified soapstock. Halt cycle once 60 minutes
of run time has been reached and perform liq-liq extraction of
floating fatty material with nonpolar solvent. A rotary evaporator
(or rotavap/rotovap) solvent from crude fatty phase to obtain
anhydrous material for characterization.
[0146] Result: 12 g fatty material, 1 wt % soap, 99 wt % FFA via
titration. [0147] Total energy usage: 1740 kWhr/metric ton FFA
produced.
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[0189] While the forgoing written description of the invention
enables one of ordinary skill to make and use what is considered
presently to be the best mode thereof, those of ordinary skill will
understand and appreciate the existence of variations,
combinations, and equivalents of the specific embodiments, methods,
and examples herein. The invention should therefore not be limited
by the above described embodiments, methods and examples, but by
all embodiments and methods within the scope and spirit of the
invention. A number of embodiments of the invention have been
described. Nevertheless, it can be understood that various
modifications may be made without departing from the spirit and
scope of the invention. Accordingly, other embodiments are within
the scope of the following claims.
* * * * *
References