U.S. patent application number 11/969699 was filed with the patent office on 2008-07-10 for process for producing bio-derived fuel with alkyl ester and iso-paraffin components.
Invention is credited to Ramin Abhari, Peter Havlik.
Application Number | 20080163543 11/969699 |
Document ID | / |
Family ID | 39593069 |
Filed Date | 2008-07-10 |
United States Patent
Application |
20080163543 |
Kind Code |
A1 |
Abhari; Ramin ; et
al. |
July 10, 2008 |
PROCESS FOR PRODUCING BIO-DERIVED FUEL WITH ALKYL ESTER AND
ISO-PARAFFIN COMPONENTS
Abstract
A process for producing a diesel fuel of biological origin. The
process includes a biological component to be trans-esterified into
a fatty acid alkyl ester. A fraction of the fatty acid alkyl ester
is hydrodeoxygenated and hydroisomerized to produce an
iso-paraffinic hydrocarbon. The fatty acid alkyl ester and the
iso-paraffin components are combined into a middle distillate
product suitable for direct use as diesel or jet fuel.
Inventors: |
Abhari; Ramin; (Bixby,
OK) ; Havlik; Peter; (Tulsa, OK) |
Correspondence
Address: |
Hall, Estill, Hardwick, Gable, Golden &Nelson, P.C.
100 North Broadway, Chase Tower, Suite 2900
Oklahoma City
OK
73102
US
|
Family ID: |
39593069 |
Appl. No.: |
11/969699 |
Filed: |
January 4, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60883529 |
Jan 5, 2007 |
|
|
|
Current U.S.
Class: |
44/308 |
Current CPC
Class: |
C10G 45/60 20130101;
C10G 45/64 20130101; C10G 2400/08 20130101; Y02E 50/13 20130101;
C10L 1/19 20130101; C10G 45/62 20130101; C10L 1/026 20130101; C10G
2400/04 20130101; C10L 1/1616 20130101; C10L 1/14 20130101; Y02E
50/10 20130101 |
Class at
Publication: |
44/308 |
International
Class: |
C10L 1/18 20060101
C10L001/18 |
Claims
1. A process for producing a diesel fuel of biological origin,
comprising: providing a biological component to be trans-esterified
into fatty acid alkyl ester, subjecting a fraction of the fatty
acid alkyl ester to hydro-deoxygenation and hydro-isomerization to
produce an iso-paraffinic hydrocarbon, and combining the fatty acid
alkyl ester and the iso-paraffin components into a middle
distillate composition suitable for direct use as diesel or jet
fuel.
2. The process of claim 1 wherein the biological component
comprises vegetable oils, animal fats, and combinations
thereof.
3. The process of claim 1 wherein the fraction of fatty acid alkyl
ester subjected to hydro-deoxygenation and hydro-isomerization is
recovered by distillation.
4. The process of claim 1 wherein the fraction of fatty acid alkyl
ester subjected to hydro-deoxygenation and hydro-isomerization is
recovered by crystallization.
5. The process of claim 1 wherein an alcohol used for
trans-esterification is methanol.
6. The process of claim 1 wherein the trans-esterification is
carried out at a temperature of about 80.degree. F. to about
200.degree. F.
7. The process of claim 1 wherein the trans-esterification catalyst
is potassium hydroxide, sodium hydroxide, or sodium methoxide.
8. The process of claim 1 wherein the hydrodeoxygenation pressure
is about 500 psig to about 2,500 psig and the temperature is about
400.degree. F. to about 800.degree. F.
9. The process of claim 1 where in the hydrodeoxygenation catalyst
is a supported NiMo, NiW, or CoMo catalyst, the support being
alumina, or alumina with phosphorous or silicon oxides.
10. The process of claim 1 wherein the hydroisomerization pressure
is about 500 psig to about 2,000 psig and the temperature is about
500.degree. F. to about 800.degree. F.
11. The process of claim 1 wherein the hydroisomerization catalyst
contains one or more of Pt, Pd, Ni, on amorphous or crystalline
supports containing one or more of alumina, fluorided alumina,
silica, ferrierite, ZSM-12, ZSM-21, ZSM-22, ZSM-23, SAPO-11,
SAPO-31, and SAPO-41.
12. The process as in any one of claims 1-11 wherein a glycerol
byproduct of trans-esterification is subjected to
hydro-deoxygenation.
13. The process as in any one of claims 1-11 wherein the fraction
of fatty acid alkyl ester is combined with a biological component
rich in free fatty acids before being subjected to
hydro-deoxygenation.
14. The process of claim 13 wherein the biological component rich
in free fatty acids is rendered fat, restaurant grease, waste
industrial frying oil, tall oil fatty acid, and combinations
thereof.
15. The process of claim 14 wherein a glycerol byproduct of
trans-esterification is used to wash the biological component rich
in free fatty acid before this biological component is subjected to
hydro-deoxygenation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit under 35 U.S.C.
119(e) of U.S. Provisional Application Ser. No. 60/883,529, filed
Jan. 5, 2007, which is hereby expressly incorporated by reference
herein in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates generally to a process for the
production of diesel fuel from renewable resources, and more
particularly, not by way of limitation, to an improved process for
the production of diesel fuel from renewable resources for use as
alternatives or additives to petroleum-based or gas-to-liquid
produced products.
[0005] 2. Brief Description of the Related Art
[0006] Processes useful for producing fatty acid alkyl esters from
renewable sources such as animal fats and vegetable oils have been
in use for many years. Examples of such processes are found in U.S.
Pat. Nos. 5,424,467; 5,389,113; 5,525,126; 6,642,399; 6,712,867;
6,768,015; 6,855,838; 6,878,837; 6,884,900; and 6,982,155, the
disclosures all of which are incorporated herein by reference. The
products of these processes are generally referred to as
"biodiesel".
[0007] Biodiesel is produced commercially by the
transesterification reaction of triglycerides (the molecular
building block of vegetable oils and fats) with methanol. Among the
advantages of biodiesel is its role as a lubricity improver when
blended with ultra-low sulfur conventional diesels.
[0008] However, several factors limit the choice of feedstock for
biodiesel production. If the triglyceride molecule is made up of
mostly saturated fatty acids, the resulting biodiesel will have
poor low temperature properties (e.g. high cloud point and pour
point). The more abundant and less expensive vegetable oils such as
palm oil (mostly saturated fatty acids) are not used for biodiesel
except when highly diluted with conventional diesel fuel and in
tropical climates.
[0009] Another factor affecting feedstock choice is the level of
free-fatty acid (FFA). Since fatty acids convert to soaps under
typical base-catalyzed transesterification conditions, high levels
of FFA result in operating problems and catalyst consumption
inefficiencies.
[0010] To this end, although processes of the existing art utilize
renewable sources to produce diesel fuel, a need exists for a
process for producing hydrocarbon products, particularly high
quality paraffinic middle distillates in high yields, from
renewable sources. It is to such a process that the present
invention is directed.
SUMMARY OF THE INVENTION
[0011] The process of the present invention produces a diesel fuel
of biological origin. A biological component, such as a vegetable
oil, an animal fat and any combination thereof, is provided to be
trans-esterified into fatty acid alkyl ester. An alcohol, such as
methanol, is used for trans-esterification of the biological
component. The trans-esterification catalyst is potassium
hydroxide, sodium hydroxide, or sodium methoxide.
Trans-esterification is carried out at a temperature of about
80.degree. F. to about 200.degree. F.
[0012] A fraction of the fatty acid alkyl ester is subjected to
hydro-deoxygenation and hydro-isomerization to produce an
iso-paraffinic hydrocarbon. The fraction of the fatty acid alkyl
ester subjected to hydro-deoxygenation and hydro-isomerization is
recovered by distillation or crystallization. The
hydrodeoxygenation pressure is about 500 psig to about 2,500 psig
and the temperature is about 400.degree. F. to about 800.degree. F.
The hydrodeoxygenation catalyst is a supported NiMo, NiW, or CoMo
catalyst. The support is alumina, or alumina with phosphorous or
silicon oxides. The hydroisomerization pressure is about 500 psig
to about 2,000 psig and the temperature is about 500.degree. F. to
about 800.degree. F. The hydroisomerization catalyst contains one
or more of Pt, Pd, Ni, on amorphous or crystalline supports
containing one or more of alumina, fluorided alumina, silica,
ferrierite, ZSM-12, ZSM-21, ZSM-22, ZSM-23, SAPO-11, SAPO-31, and
SAPO-41.
[0013] The fatty acid alkyl ester and the iso-paraffin components
are combined into a middle distillate composition suitable for
direct use as diesel or jet fuel.
[0014] The fraction of fatty acid alkyl ester is combined with a
biological component rich in free fatty acids before being
subjected to hydro-deoxygenation. The biological component rich in
free fatty acids is rendered fat, restaurant grease, waste
industrial frying oil, tall oil fatty acid, and combinations
thereof.
[0015] A glycerol byproduct of trans-esterification is used to wash
the biological component rich in free fatty acid before this
biological component is subjected to hydro-deoxygenation. The
glycerol byproduct of trans-esterification may be subjected to
hydro-deoxygenation.
[0016] An object of certain embodiments of the invention is
converting triglycerides with varying levels of saturation and
free-fatty acid to diesel blends having both iso-paraffinic and
methyl ester components. The iso-paraffin component improves low
temperature properties while the methyl ester improves
lubricity.
[0017] Another object of certain embodiments of the invention is to
produce a high quality middle distillate with improved yields and
properties that meet the generally accepted specifications for
conventional fuels.
[0018] Another object of certain embodiments of the invention is to
produce kerosene, jet fuel, or diesel from renewable feedstock.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic diagram illustrating one embodiment of
the process for converting a renewable feedstock to a diesel fuel
blend having improved low temperature properties.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The process of the present invention relates to converting a
renewable feedstock to a diesel fuel blend having improved low
temperature properties. The process of the present invention
produces high yields of an improved middle distillate product.
[0021] The term "renewable feedstock" refers to animal fats,
vegetable oils, plant fats and oils, rendered fats, restaurant
grease and waste industrial frying oils, tall oil fatty acids and
combinations thereof.
[0022] The term "middle distillate product(s)" and "middle
distillate" refer to hydrocarbon mixtures with a boiling point
range that corresponds substantially with that of kerosene and gas
oil fractions obtained in a conventional atmospheric distillation
of crude oil material. The middle distillate boiling point range
may include temperatures between about 150.degree. C. and about
600.degree. C., with a fraction boiling point between about
200.degree. C. and about 360.degree. C.
[0023] The term "middle distillate fuel" refers to jet fuel,
kerosene, diesel fuel, gasoline and combinations thereof.
[0024] The term "FAME" refers to fatty acids methyl esters.
[0025] Referring now to the FIG. 1, shown therein is a schematic of
the operation of the process in accordance with the present
invention as described herein. A renewable feedstock 10, containing
glycerides, is introduced into a transesterification unit 12. The
renewable feedstock 10 may be pretreated before being introduced
into the process. It should be understood that any method known to
one of ordinary skill in the art for pretreating the feedstock may
be utilized. In one embodiment, the fatty acids are mostly
saturated fatty acids, such as found in palm oil. However, it
should be understood that any fatty acid containing varying levels
of saturation known to one of ordinary skill in the art may be
used. Stream 14 containing an alcohol and stream 16 containing a
catalyst are added to the transesterification unit 12 and reacted
with the fatty acid. In one embodiment, methanol and a potassium
hydroxide catalyst are used. However, it should be understood that
although methanol is utilized in one embodiment of the present
invention that any alcohol known by one of ordinary skill in the
art and used in accordance with the present invention may be
utilized. Further, although potassium hydroxide is used in one
embodiment as the transesterification catalyst, it should be
understood that any variety of catalyst such as, but not limited
to, sodium hydroxide, sodium methoxide or the like may be utilized
in accordance with the present invention.
[0026] In the transesterification unit 12, the fatty acid reacts
with the alcohol using the catalyst to produce an effluent 18
containing biodiesel. An effluent 20 containing crude glycerol
byproduct is also produced from the reaction in the
transesterification unit 12.
[0027] When palm oil, for example, is utilized in the process, the
saturated fatty acids are of C.sub.16 carbon length and the
unsaturated fatty acids are C.sub.18. The C.sub.16 fatty acids
methyl esters (FAME) are stripped from the biodiesel to improve the
cold flow properties of the biodiesel. Effluent 18 containing
biodiesel is introduced into a vacuum distillation unit 22 so that
the C.sub.16 FAME is stripped from the biodiesel to produce
effluent 24 containing C.sub.16 FAME and effluent 26 containing
C.sub.18 FAME. It should be understood that although the C.sub.16
FAME is shown being stripped from the biodiesel by vacuum
distillation, the stripping of the C.sub.16 FAME may be
accomplished by distillation under pressure, stream stripping, thin
film evaporators, wiped film evaporators or the like.
[0028] Effluent 24 containing the C.sub.16 FAME is introduced into
a hydrotreater unit 30. The C.sub.16 FAME may be combined with a
free-fatty acid rich stream 32 and a hydrogen stream 34. The high
melt point C.sub.16 FAME fraction from the transesterification unit
12 is converted to n-paraffins (for example, n-hexadecane (cetane))
(effluent stream 36) and water (effluent stream 38) in the
hydrotreater unit 30, according to the following example equation
(1):
C.sub.15H.sub.31--COO--CH.sub.3+3H.sub.2.fwdarw.C.sub.16H.sub.34+2H.sub.-
2O+CH.sub.4 (1)
[0029] In one embodiment, the hydrotreating process in the
hydrotreater unit 30 employs a heterogenous supported bifunctional
catalyst. The bifunctional catalyst is bimetallic. However, it
should be understood that any variety of catalyst may be utilized
in the hydrotreating process in accordance with the present
invention. Examples of hydrotreating catalysts suitable for
hydrodeoxygenation and olefin saturation include sulfided Ni--W
(nickel-tungsten), Ni--Mo (nickel-molybdenum) and Co--Mo
(cobalt-molybdenum) on an alumina, or alumina with phosphorus oxide
or silicon oxide support. The catalysts may be sulfided during
startup, or pre-sulfided and active when loaded into the
hydrotreater unit 30. The hydrotreater unit 30 deoxygenates fatty
acids and saturates double bonds. In the case of fatty acid esters
or glycerides the ester linkages are broken and free-fatty acids
are deoxygenated and their double bonds saturated. The hydrotreater
unit 30 operates at typical refining pressure and temperature
conditions: LHSV (0.1-10 hr.sup.-1), temperature (300-850.degree.
F.), pressure (250-3000 Psig) and gas/oil ratio (1000
SCF/bbl-20,000 SCF/bbl). However, it should be understood by one of
ordinary skill in the art that there may be times when the
hydro-treater unit 30 may operate outside of typical refining
pressure and temperature conditions in accordance with the present
invention.
[0030] The n-paraffin product from the hydro-treater unit 30 is
introduced in a hydro-isomerizer unit 40 where the n-hexadecane
product is converted to lower melting point branched isomers. A
hydro-isomerization catalyst contains one or more of Pt, Pd, Ni, on
amorphous or crystalline supports containing one or more of
alumina, fluorided alumina, silica, ferrierite, ZSM-12, ZSM-21,
ZSM-22, ZSM-23, SAPO-11, SAPO-31, and SAPO-41. Hydrogen 41 may also
be added to the hydro-isomerizer unit 40 as needed. The
hydro-isomerizer unit 40 operates at typical refining pressure and
temperature conditions: LHSV (0.1-10 hr.sup.-1), temperature
(300-850.degree. F.), pressure (250-3000 Psig) and gas/oil (1000
SCF/bbl-20,000 SCF/bbl). However, it should be understood by one of
ordinary skill in the art that there may be times when the
hydroisomerizer unit 40 may operate outside of typical refining
pressure and temperature conditions in accordance with the present
invention.
[0031] An effluent stream 42 containing isomers from the
hydro-isomerizer unit 40 are introduced in a fuel blending unit 44
and blended with the C.sub.18 FAME product of the
trans-esterification unit 12 or vacuum distillation unit 18. An
effluent 46 containing a final diesel fuel product is produced from
the fuel blending unit 44. Since the hydro-treater unit 30
desulfurizes the renewable feedstock under the hydro-deoxygenation
conditions of, for example, Equation (1), the alkyl ester component
of the blended final diesel fuel product acts to improve
lubricity.
[0032] There are a number of ways that the transesterification
process units can be integrated with hydroprocessing units to
achieve additional operational synergies. For example, the glycerol
byproduct of the transesterification unit 12 can be used to wash
salt contaminants from the high free-fatty acid feeds 32 to the
hydrotreater unit 30 before the biological component rich in
free-fatty acid is subjected to hydro-deoxygenation. Alternatively,
the glycerol byproduct may be co-fed to the hydrotreater unit 30
and subjected to hydro-deoxygenation to yield propane diols and
other value-added co-products.
[0033] From the above description, it is clear that the present
invention is well adapted to carry out the objects and to attain
the advantages mentioned herein as well as those inherent in the
invention. While presently preferred embodiments of the invention
have been described for purposes of this disclosure, it will be
understood that numerous changes may be made which will readily
suggest themselves to those skilled in the art and which are
accomplished within the spirit of the invention disclosed and
claimed.
* * * * *