U.S. patent application number 14/851554 was filed with the patent office on 2016-05-19 for composition comprising a mixture of at least three different long chain secondary alcohols.
This patent application is currently assigned to .. The applicant listed for this patent is Chevron U.S.A. Inc.. Invention is credited to Sven Ivar Hommeltoft, Cedrick Mahieux.
Application Number | 20160137569 14/851554 |
Document ID | / |
Family ID | 54542758 |
Filed Date | 2016-05-19 |
United States Patent
Application |
20160137569 |
Kind Code |
A1 |
Hommeltoft; Sven Ivar ; et
al. |
May 19, 2016 |
COMPOSITION COMPRISING A MIXTURE OF AT LEAST THREE DIFFERENT LONG
CHAIN SECONDARY ALCOHOLS
Abstract
A composition to be converted to a lubricant is provided. The
composition comprises a mixture of at least three different long
chain secondary alcohols having the following chemical structure:
##STR00001## where R1' and R2' are independently selected from
C.sub.5-C.sub.21 linear or branched alkyls.
Inventors: |
Hommeltoft; Sven Ivar;
(Pleasant Hill, CA) ; Mahieux; Cedrick; (Benicia,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chevron U.S.A. Inc. |
San Ramon |
CA |
US |
|
|
Assignee: |
.
|
Family ID: |
54542758 |
Appl. No.: |
14/851554 |
Filed: |
September 11, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14540420 |
Nov 13, 2014 |
9193650 |
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14851554 |
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Current U.S.
Class: |
568/881 |
Current CPC
Class: |
Y02P 20/582 20151101;
C07C 45/48 20130101; C07C 45/48 20130101; C07C 29/145 20130101;
C07C 29/145 20130101; C07C 31/125 20130101; C07C 29/145 20130101;
C07C 49/04 20130101; C07C 33/02 20130101; C07C 31/02 20130101 |
International
Class: |
C07C 31/125 20060101
C07C031/125; C07C 29/145 20060101 C07C029/145 |
Claims
1. A composition to be converted to a lubricant, comprising a
mixture of at least three different long chain secondary alcohols
having a chemical structure of: ##STR00010## where R1' and R2' are
independently selected from C.sub.5-C.sub.21 linear or branched
alkyls.
2. The composition of claim 1, wherein the composition is made from
saturated fatty acids from coconut oil and comprises a mixture of
C.sub.19-C.sub.27 secondary alcohols.
3. The composition of claim 1, wherein the composition is made from
saturated fatty acids from beef tallow and comprises a mixture of
C.sub.29-C.sub.35 secondary alcohols.
4. The composition of claim 1, wherein the composition is made from
a fatty acid mixture consisting predominantly of stearic acid and
comprises a mixture of C.sub.29-C.sub.35 secondary alcohols.
5. The composition of claim 1, wherein a non-terminal location of
an OH in the chemical structure ensures a lower melting point and
better cold flow properties for the lubricant.
6. The composition of claim 1, wherein the composition is made from
a mixture of three or more saturated fatty acids.
7. The composition of claim 6, wherein the mixture of three or more
saturated fatty acids are obtained from a biological material
selected from the group consisting of coconut oil, corn oil,
linseed oil, olive oil, palm oil, palm kernel oil, rapeseed oil,
safflower oil, soybean oil, sunflower oil, and mixtures
thereof.
8. The composition of claim 6, wherein the mixture of three or more
saturated fatty acids are obtained from a source of triglycerides
selected from the group consisting of algae, animal tallow,
zooplankton, and mixtures thereof.
9. The composition of claim 1, made by a process comprising: a.
contacting a mixture of fatty acids with a ketonization catalyst in
a ketonization zone under ketonization conditions to provide at
least three different long chain ketones, and b. contacting the at
least three different long chain ketones with a selective ketone
hydrogenation catalyst in a ketone hydrogenation zone in the
presence of hydrogen gas under selective ketone hydrogenation
conditions to provide the mixture of at least three different long
chain secondary alcohols that correspond to the at least three
different long chain ketones.
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/540,420, filed on Nov. 13, 2014 and titled
"LONG CHAIN SECONDARY ALCOHOLS FROM FATTY ACIDS AND FATTY OILS",
herein incorporated in its entirety.
TECHNICAL FIELD
[0002] This disclosure relates to processes for producing long
chain secondary alcohols from fatty acids and fatty oils and to
long chain secondary alcohol products.
BACKGROUND
[0003] Heretofore, long chain alcohols have typically been prepared
by hydrogenation of fatty oils and fatty acids or through
Fischer-Tropsch (F-T) type chemistry, both of which place the
alcohol group towards the end of the molecule. Also regarding chain
length, it is typically expensive to prepare alcohols with a carbon
chain length above that of available fatty acids, i.e., typically
up to C.sub.18 for the most common fatty acids and fatty oil
feedstocks.
[0004] There is a need for processes for efficiently producing long
chain secondary alcohols from fatty acids and fatty oils.
SUMMARY
[0005] In an embodiment there is provided a process comprising
contacting at least one fatty acid with a ketonization catalyst in
a ketonization zone under ketonization conditions to provide at
least one long chain ketone according to the following Scheme
1:
##STR00002##
wherein R.sub.1 and R.sub.2 are independently selected from the
group consisting of C.sub.5-C.sub.21 linear or branched alkyl and
C.sub.5-C.sub.21 linear or branched alkenyl, and contacting the at
least one long chain ketone with a selective ketone hydrogenation
catalyst in a ketone hydrogenation zone in the presence of hydrogen
gas under selective ketone hydrogenation conditions to provide at
least one long chain secondary alcohol according to the following
Scheme 2:
##STR00003##
wherein R.sub.1 and R.sub.2 are the same or different; when R.sub.1
is alkyl R.sub.1'=R.sub.1, when R.sub.2 is alkyl R.sub.2'=R.sub.2,
when R.sub.1 is alkenyl R.sub.1' is alkyl or alkenyl, when R.sub.2
is alkenyl R.sub.2' is alkyl or alkenyl, R.sub.1 and R.sub.1' have
an equal number of carbon atoms, R.sub.2 and R.sub.2' have an equal
number of carbon atoms, and the step of contacting the at least one
long chain ketone with the selective ketone hydrogenation catalyst
comprises selectively hydrogenating the at least one long chain
ketone to selectively provide the at least one long chain secondary
alcohol.
[0006] In another embodiment, there is provided at least one long
chain secondary alcohol product, or a product comprising a mixture
of long chain secondary alcohols, prepared by processes as
disclosed herein.
[0007] In a further embodiment there is provided a process
comprising contacting at least one fatty acid with a ketonization
catalyst in a ketonization zone under ketonization conditions to
provide at least one long chain ketone having at least 11 carbon
atoms according to the following Scheme 1:
##STR00004##
wherein R.sub.1 and R.sub.2 are independently selected from the
group consisting of C.sub.5-C.sub.21 linear or branched alkyl and
C.sub.5-C.sub.21 linear or branched alkenyl, and contacting the at
least one long chain ketone with a selective ketone hydrogenation
catalyst in a ketone hydrogenation zone in the presence of hydrogen
gas under selective ketone hydrogenation conditions to provide at
least one long chain secondary alcohol according to the following
Scheme 2:
##STR00005##
wherein R.sub.1 and R.sub.2 are the same or different, when R.sub.1
is alkyl R.sub.1'=R.sub.1, when R.sub.2 is alkyl R.sub.2'=R.sub.2,
when R.sub.1 is alkenyl R.sub.1' is alkyl or alkenyl, when R.sub.2
is alkenyl R.sub.2' is alkyl or alkenyl, R.sub.1 and R.sub.1' have
an equal number of carbon atoms, and R.sub.2 and R.sub.2' have an
equal number of carbon atoms. The selective ketone hydrogenation
catalyst lacks catalytic activity for dehydration of the long chain
secondary alcohol under said selective ketone hydrogenation
conditions such that ketone conversion to the corresponding alkene
or alkane is prevented, and the step of contacting the at least one
long chain ketone with the selective ketone hydrogenation catalyst
comprises selectively hydrogenating the at least one ketone to
selectively provide the at least one long chain secondary
alcohol.
[0008] In yet another embodiment there is provided a process
comprising i) reacting a first fatty acid with a second fatty acid
to form a long chain ketone having at least 11 carbon atoms, and
ii) selectively hydrogenating the long chain ketone to selectively
form the corresponding long chain secondary alcohol, wherein i) and
ii) are jointly performed according to the following Scheme 3:
##STR00006##
wherein each of m and n is an integer in the range from 4 to 20,
and wherein m and n may be equal or unequal such that the first
fatty acid and the second fatty acid may be the same or different.
The step of reacting the first fatty acid with the second fatty
acid comprises contacting the first fatty acid and the second fatty
acid with a ketonization catalyst in a ketonization zone under
ketonization conditions. The step of selectively hydrogenating the
long chain ketone comprises contacting the long chain ketone with a
selective ketone hydrogenation catalyst in a ketone hydrogenation
zone in the presence of hydrogen gas under selective ketone
hydrogenation conditions, and the step of selectively hydrogenating
the long chain ketone is performed in the absence of a material
that promotes dehydration of the secondary alcohol under said
selective ketone hydrogenation conditions such that conversion to
the corresponding alkene or alkane is prevented.
DETAILED DESCRIPTION
[0009] Conventional processes for preparing alcohols with a carbon
chain length above that of available fatty acids are expensive.
Also, such conventional processes place the alcohol group toward
the end of the molecule.
[0010] For some applications it may be desirable to make
inexpensive long chain alcohols in which the alcohol group is
placed away from the termini of the molecule. Such a non-terminal
location of the alcohol group ensures a lower melting point and
thus better cold flow properties of derivatives of these alcohols,
which is an important consideration, for example, if the alcohols
are to be used for preparing products for lubricant
applications.
[0011] Also for lubricant applications, it may be important to
prepare molecules with a sufficiently high boiling point and
viscosity to meet specifications for most lubricant products. This
typically requires carbon chains considerably longer than the
C.sub.16-C.sub.18 chains that are made simply by hydrogenation of
the most commonly available fatty acids and fatty oil
feedstocks.
[0012] Applicant has discovered a new route to make long chain
secondary alcohols, from fatty acids and fatty oils, in which the
OH group may be placed non-terminally in the molecule and in which
the carbon chain length is about twice (2.times.) the length of the
carbon chain of alcohols prepared by simple hydrogenation of fatty
acids and fatty oils.
[0013] More specifically, Applicant has demonstrated that under the
right conditions of temperature and pressure and in the presence of
alumina catalyst, it is possible to perform fatty acid ketonization
with concomitant loss of CO.sub.2 and H.sub.2O to give a heavy or
long chain ketone. Subsequent reduction of the long chain ketone
generates long chain secondary alcohols wherein the OH group is
disposed non-terminally in the molecule.
[0014] Ketone reduction to provide long chain alcohols may be
performed by chemical means using reducing agents such as
LiAlH.sub.4. However, chemical reduction of the ketone is
expensive, and in addition we have found the reactivity of the
ketones towards usually very effective reducing agents such as
LiAlH.sub.4 decreases with increasing hydrocarbon chain length
making the chemical reagents even more expensive to use.
Furthermore, hydrogenation of long chain ketones over a
conventional alumina supported or silica-alumina supported
hydrotreating catalyst, e.g. a catalyst of the Co--Mo or Ni--Mo
types, results in considerable formation of the corresponding
alkanes, with concomitant decrease in yield of the desired long
chain secondary alcohol product.
[0015] Applicant has further discovered that such alkane formation
results from alcohol dehydration catalyzed by alumina present in
the support material of conventional catalysts, i.e., the alumina
in conventional catalysts dehydrates the initially formed alcohol
to give an olefin that is more easily hydrogenated than the long
chain ketone. Consequently, long chain ketones tend to be reduced
all the way to the corresponding alkane in the presence of an
alumina-supported hydrogenation catalyst.
[0016] In an embodiment, long chain secondary alcohols may be
prepared by ketonization of at least one fatty acid to provide a
long chain ketone, and thereafter the long chain ketone may be
selectively hydrogenated to the corresponding secondary alcohol
with excellent selectivity using a selective ketone hydrogenation
catalyst that at least substantially lacks catalytic activity for
alcohol dehydration under the hydrogenation conditions used. Such
selective ketone hydrogenation allows ketone conversion to the
corresponding secondary alcohol at high selectivity (e.g., >80%
selectivity) at 90% conversion. While not being bound by theory,
conversion of the long chain ketone to products other than the
corresponding secondary alcohol may be accounted for, at least in
large part, by non-catalytic (e.g., thermal) alcohol dehydration.
In long chain secondary alcohols prepared in this manner, the
alcohol group may be placed at a non-terminal location of the
molecule. As a non-limiting example, the hydroxyl group may be
located at least six carbon atoms from a terminal carbon atom of
the molecule, and often in the range from 6 to 21 carbon atoms from
a terminal carbon atom of the molecule.
Catalysts for Ketonization
[0017] In an embodiment, a suitable catalyst for ketonization may
comprise alumina. In an embodiment, the ketonization catalyst may
comprise at least 95 wt %, at least 99 wt %, or at least 99.5 wt %
alumina. In an embodiment, the fresh ketonization catalyst may be
calcined at a temperature in the range from 700 to 1100.degree. F.
(371 to 593.degree. C.) for a time period in the range from 0.5 to
24 hours prior to contacting the ketonization catalyst with a
reactant (long chain carboxylic acid or fatty acid). In an
embodiment, the fresh ketonization catalyst may be calcined in the
presence of steam. In an embodiment, the ketonization catalyst may
comprise gamma alumina. In an embodiment, the ketonization catalyst
may consist essentially of alumina.
[0018] In an embodiment, the surface area of the alumina catalyst
for ketonization may be in the range from 15 to 500 m.sup.2/g of
catalyst, or from 50 to 400 m.sup.2/g of catalyst, or from 100 to
250 m.sup.2/g of catalyst. In an embodiment, an alumina catalyst
useful for ketonization reactions as disclosed herein may have
various shapes including, for example, granules, pellets, spheres,
extrudates, and the like. The alumina catalyst may be disposed
within a ketonization zone. A ketonization zone is not limited to
any particular reactor type. For example, a ketonization zone may
use a fixed-, fluidized-, or moving bed reactor.
[0019] Over time, the ketonization catalyst may passivate and lose
activity. An alumina catalyst that has become passivated to varying
degrees following ketonization may be regenerated, e.g., as
described in commonly assigned U.S. patent application Ser. No.
14/540,723, filed on Nov. 13, 2014, and entitled Ketonization
process using oxidative catalyst regeneration (Atty. Docket No.
T-9577).
Fatty Acid Ketonization
[0020] A ketone product may be prepared by contacting at least one
fatty acid with a ketonization catalyst in a ketonization zone
under ketonization conditions according to the following scheme
(Scheme 1), wherein R.sub.1 and R.sub.2 are saturated or
unsaturated aliphatic groups, and wherein R.sub.1 and R.sub.2 may
be the same or different. As a non-limiting example, R.sub.1 and
R.sub.2 may be independently selected from C.sub.5-C.sub.21 linear
or branched alkyl and C.sub.5-C.sub.21 linear or branched
alkenyl.
##STR00007##
In a sub-embodiment, R.sub.1 and R.sub.2 may be independently
selected from C.sub.7-C.sub.17 linear or branched alkyl or alkenyl,
or from C.sub.9-C.sub.17 linear or branched alkyl or alkenyl, or
from C.sub.9-C.sub.15 linear or branched alkyl or alkenyl, or from
C.sub.15-C.sub.17 linear or branched alkyl or alkenyl. In an
embodiment, ketonization may also be known as ketonic
decarboxylation or fatty acid decarboxylation-coupling.
[0021] In an embodiment, the step of contacting the at least one
fatty acid with the ketonization catalyst may comprise feeding a
feedstock comprising the at least one fatty acid to the
ketonization zone. In an embodiment, feedstocks for ketonization as
disclosed herein may be derived from a triglyceride-containing
biomass source such as oils or fats from plants and/or animals. In
an embodiment, the feedstock may be obtained from biological
material (e.g., fatty biomass) having a lipid content greater than
(>) 30 wt % on a dry weight basis, or >50, or >70, or
>90, or >95, or >99 wt % on a dry weight basis. In an
embodiment, the biological material may comprises vegetable oil,
animal tallow, algae, and combinations thereof. In an embodiment,
the fatty acid feedstock may be derived from other, non-biomass,
sources (e.g., Fischer-Tropsch synthesis). Such alternatively
derived fatty acids may be mixed or blended with biomass derived
fatty acids prior to ketonization, e.g., to alleviate logistical
and/or supply related issues involving biomass.
[0022] In an embodiment, feedstocks for ketonization may comprise
at least one fatty acid reactant or a mixture of fatty acid
reactants. In an embodiment, the at least one fatty acid reactant
for ketonization may comprise a mixture of at least two (2) fatty
acids. In an embodiment, reactants for ketonization may comprise
C.sub.6-C.sub.22 fatty acids and/or C.sub.6-C.sub.22 fatty acid
derivatives. In an embodiment, such fatty acid derivatives may
include C.sub.6-C.sub.22 fatty acid mono-, di-, and triglycerides,
C.sub.6-C.sub.22 acyl halides, and C.sub.6-C.sub.22 salts of fatty
acids. In a sub-embodiment, the fatty acids and/or fatty acid
derivatives for ketonization may be in the range from
C.sub.8-C.sub.18, or in the range from C.sub.16-C.sub.18. In an
embodiment, at least one fatty acid for ketonization may be
obtained from biological material, including various organisms and
biological systems. In an embodiment, the at least one fatty acid
may be obtained from at least one naturally occurring triglyceride,
for example, wherein the triglyceride may be obtained from biomass.
In an embodiment, feedstocks for ketonization may comprise at least
95 wt % fatty acids or at least 99 wt % fatty acids.
[0023] In an embodiment, reactants for ketonization may be derived
from one or more triglyceride-containing vegetable oils such as,
but not limited to, coconut oil, corn oil, linseed oil, olive oil,
palm oil, palm kernel oil, rapeseed oil, safflower oil, soybean
oil, sunflower oil, and the like. Additional or alternative sources
of triglycerides, which can be hydrolyzed to yield fatty acids,
include, but are not limited to, algae, animal tallow, and
zooplankton.
[0024] In an embodiment, reactants for ketonization may include,
without limitation, C.sub.8-C.sub.22 fatty acids, and combinations
thereof. Examples of suitable saturated fatty acids may include,
without limitation, caproic acid (C.sub.6), caprylic acid
(C.sub.8), capric acid (C.sub.10), lauric acid (C.sub.12), myristic
acid (C.sub.14), palmitic acid (C.sub.16), stearic acid (C.sub.18),
eicosanoic acid (C.sub.20). Examples of unsaturated fatty acids may
include, without limitation, palmitoleic acid, oleic acid, and
linoleic acid. Reactants for ketonization may further include,
without limitation, palm kernel oil, palm oil, coconut oil, corn
oil, soy bean oil, rape seed (canola) oil, poultry fat, beef
tallow, and their respective fatty acid constituents, and
combinations thereof.
[0025] In an embodiment, the reactants for the ketonization
reaction or step may be hydrogenated to substantially saturate some
or all of the double bonds prior to ketonization. In cases where
the fatty oils, i.e., triglycerides, are hydrolyzed to fatty acids,
such saturation of the double bonds may be done before or after the
hydrolysis.
[0026] In some aspects, wherein the above-mentioned hydrolyzed
triglyceride sources contain mixtures of saturated fatty acids,
mono-unsaturated fatty acids, and polyunsaturated fatty acids, one
or more techniques may be employed to isolate, concentrate, or
otherwise separate one or more types of fatty acids from one or
more other types of fatty acids in the mixture (see, e.g., U.S.
Pat. No. 8,097,740 to Miller).
[0027] Prior to contacting the reactant with the ketonization
catalyst in the ketonization zone, the ketonization catalyst may be
calcined. In an embodiment, the step of calcining the ketonization
catalyst may be performed in the presence of steam. In an
embodiment, the step of calcining the ketonization catalyst may be
performed at a temperature in the range from 400 to 600.degree. C.,
or from 450 to 500.degree. C., for a time period in the range from
0.5 to 10 hours, or from 1 to 2 hours.
[0028] In an embodiment, a suitable catalyst for fatty acid
ketonization may comprise alumina. In an embodiment, the
ketonization catalyst may comprise substantially pure gamma
alumina. In an embodiment, the ketonization catalyst may consist
essentially of alumina.
[0029] Suitable ketonization conditions may include a temperature
in the range from 100 to 500.degree. C., or from 300 to 450.degree.
C.; a pressure in the range from 0.5 to 100 psi, or from 5 to 30
psi; and a liquid hourly space velocity (LHSV) in the range from
0.1 to 50 h.sup.-1, or from 0.5 to 10 h.sup.-1. In an embodiment,
the partial pressure of the fatty acid in the ketonization zone may
be maintained in the range of 0.1 to 30 psi. The ketonization
process can be carried out in batch or continuous mode, with
recycling of unconsumed starting materials if required.
[0030] In an embodiment, the decarboxylation reaction may be
conducted in the presence of at least one gaseous- or liquid
feedstock diluent. In an embodiment, the ketonization reaction may
be carried out while the fatty acid is maintained in the vapor
phase. Conditions for fatty acid ketonization are disclosed in
commonly assigned U.S. patent application Ser. No. 13/486,097,
filed Jun. 1, 2012, entitled Process for producing ketones from
fatty acids. In an embodiment, a fatty acid reactant for the
ketonization reaction may comprises a mixture of at least two (2)
fatty acids such that the ketone product may comprise a mixture of
at least three (3) different long chain ketones, each of which may
be selectively hydrogenated to provide a mixture of at least three
(3) different long chain secondary alcohols.
[0031] In an embodiment, the long chain ketones provided by the
ketonization reaction can be separated from by-products (such as
oligomeric or polymeric species and low molecular weight
"fragments" from the fatty acid chains) by distillation. For
example, in an embodiment the crude reaction product can be
subjected to a distillation-separation at atmospheric or reduced
pressure through a packed distillation column. In an embodiment,
the ketonization product may be a wax under ambient conditions.
[0032] The long chain ketones produced from fatty acids, e.g., as
disclosed hereinabove, may be converted to their corresponding long
chain secondary alcohol by selective ketone hydrogenation over a
selective ketone hydrogenation catalyst, e.g., as disclosed
hereinbelow.
Catalysts for Selective Ketone Hydrogenation
[0033] A catalyst for the selective hydrogenation of long chain
ketones to the corresponding secondary alcohols may be referred to
herein as a "selective ketone hydrogenation catalyst." In an
embodiment, the selective ketone hydrogenation catalyst for
selective hydrogenation of long chain (e.g., C.sub.11+) ketones may
comprise a metal selected from Pt, Pd, Ru, Ni, Co, Mo, Cr, Cu, Rh,
and combinations thereof. In an embodiment, the selective ketone
hydrogenation catalyst may further comprise a support material. In
an embodiment, the support material may be selected from carbon,
silica, magnesia, titania, and combinations thereof. In an
embodiment, at least some metal component(s) of the hydrogenation
catalyst may be in elemental form. As a non-limiting example, the
hydrogenation catalyst may comprise a metal selected from Pt, Pd,
Ru, Ni, Rh, and combinations thereof, and the metal may be in
elemental form in the hydrogenation catalyst. In a sub-embodiment,
the hydrogenation catalyst may comprise a metal selected from Pt,
Pd, and combinations thereof, and a support material comprising
carbon, silica, magnesia, titania, and combinations thereof. In an
embodiment, the hydrogenation catalyst may be unsupported meaning,
for example, that the metal may be present either in finely divided
form (e.g., as metal powder) or in pelletized or extruded or other
structural form without the presence of a support material.
[0034] In an embodiment, the selective ketone hydrogenation
catalyst lacks, or is devoid of, any component that promotes the
dehydration of alcohols, such that the hydrogenation catalyst as a
whole lacks catalytic activity for dehydration of the long chain
secondary alcohol, under the conditions used for the selective
hydrogenation of long chain ketones, such that ketone conversion to
the corresponding alkene or alkane is prevented. Because the long
chain ketones as disclosed herein exhibit comparatively low
reactivity in the ketone hydrogenation reaction, e.g., in
comparison with C.sub.3 or C.sub.4 ketones, more forcing conditions
may be required for hydrogenation as compared to hydrogenation of
lighter ketones; such (more forcing) conditions would be expected
to exacerbate the negative effect on product selectivity of a
hydrogenation catalyst having dehydration functionality. This
highlights the significance of using a selective ketone
hydrogenation catalyst, in processes as disclosed herein, for the
efficient conversion of long chain ketones to the corresponding
long chain secondary alcohols in high yield.
[0035] In an embodiment, a selective ketone hydrogenation catalyst
will lack alumina. As an example, the selective ketone
hydrogenation catalyst may be prepared without the use of an
alumina component and with a support material, if any, lacking an
alumina component, such that the selective ketone hydrogenation
catalyst contains at most only trace amounts of alumina that are
insufficient to be catalytically effective in dehydrating long
chain secondary alcohols under the hydrogenation conditions as
disclosed herein for the selective hydrogenation of long chain
ketones to the corresponding secondary alcohols.
[0036] This is in stark contrast to conventional hydrotreating
catalysts having alumina support material that is the major
catalyst component by weight and volume. Applicant has observed
that the presence of alumina, e.g., in conventional hydrotreating
catalysts, negatively impacts the conversion of long chain ketones
to the corresponding secondary alcohol product(s) as disclosed
herein.
[0037] In an embodiment, the surface area of the hydrogenation
catalyst may be in the range from 15 to 1000 m.sup.2/g of catalyst,
or from 100 to 600 m.sup.2/g of catalyst, or from 250 to 450
m.sup.2/g of catalyst. In an embodiment a selective ketone
hydrogenation catalyst, useful for selective hydrogenation of long
chain ketones as disclosed herein, may have various shapes
including, for example, powder, granules, pellets, spheres,
extrudates, and the like. The selective ketone hydrogenation
catalyst may be disposed within a ketone hydrogenation zone or
ketone hydrogenation reactor. The ketone hydrogenation zone is not
limited to any particular reactor type.
Long Chain Secondary Alcohols by Selective Hydrogenation of Long
Chain Ketones
[0038] As described hereinabove, a long chain ketone may be
prepared, e.g., according to Scheme 1 by contacting at least one
fatty acid with a ketonization catalyst in a ketonization zone
under ketonization conditions. The long chain ketone may then be
selectively hydrogenated by contacting the long chain ketone with a
selective ketone hydrogenation catalyst in a ketone hydrogenation
zone under selective ketone hydrogenation conditions according to
the following Scheme 2 to provide a long chain secondary
alcohol.
##STR00008##
[0039] In Schemes 1 and 2, R.sub.1 and R.sub.2 may be the same or
different, R.sub.1 and R.sub.2 may be independently selected from
C.sub.5-C.sub.21 linear or branched alkyl and C.sub.5-C.sub.21
linear or branched alkenyl, wherein: when R.sub.1 is alkyl
R.sub.1'=R.sub.1, when R.sub.2 is alkyl R.sub.2'=R.sub.2, when
R.sub.1 is alkenyl R.sub.1' is alkyl or alkenyl, when R.sub.2 is
alkenyl R.sub.2' is alkyl or alkenyl, and wherein R.sub.1 and
R.sub.1' have an equal number of carbon atoms, and R.sub.2 and
R.sub.2' have an equal number of carbon atoms. In an embodiment,
R.sub.1' and R.sub.2' may be independently selected from
C.sub.5-C.sub.21 linear or branched alkyl, or from C.sub.7-C.sub.17
linear or branched alkyl, or from C.sub.9-C.sub.17 linear or
branched alkyl, or from C.sub.9-C.sub.15 linear or branched alkyl,
or from C.sub.15-C.sub.17 linear or branched alkyl.
[0040] While not being bound by theory, in an embodiment wherein
R.sub.1 and R.sub.2 are alkenyl, the product alcohol may be the
corresponding saturated alcohol, since alkenyl group hydrogenation
is typically more facile than ketone hydrogenation. As an example,
when R.sub.1 is alkenyl R.sub.1' may be alkyl, and when R.sub.2 is
alkenyl R.sub.2' may be alkyl.
[0041] In an embodiment, the at least one fatty acid may comprise a
mixture of at least two (2) fatty acids, such that the long chain
ketone prepared according to Scheme 1 may comprise a mixture of at
least three (3) different long chain ketones, and the long chain
secondary alcohol prepared according to Scheme 2 may similarly
comprise a mixture of at least three (3) different long chain
secondary alcohols.
[0042] In an embodiment, the selective ketone hydrogenation
catalyst will lack catalytic activity for dehydration of the long
chain secondary alcohol under the selective ketone hydrogenation
conditions used such that, during the step of contacting the long
chain ketone with the selective ketone hydrogenation catalyst,
ketone conversion to the corresponding alkene or alkane is
prevented or hindered. As a result, the corresponding secondary
alcohol may be obtained from the long chain ketone with excellent
selectivity (e.g., >80% selectivity at 90% conversion).
[0043] In an embodiment, a process for preparing long chain
secondary alcohols may comprise avoiding contact of the at least
one long chain ketone with alumina during the selective ketone
hydrogenation step. For example, alumina promotes alcohol
dehydration to alkenes, which may in turn be converted to alkanes
during conventional hydrogenation, thereby substantially or greatly
decreasing the yield of long chain secondary alcohols. Accordingly
in an embodiment, the selective ketone hydrogenation catalyst as
disclosed herein may be prepared without the use of alumina. In an
embodiment, alumina or other material(s) that promote(s) alcohol
dehydration may be specifically excluded from the selective ketone
hydrogenation catalyst and the ketone hydrogenation zone.
[0044] In an embodiment, the selective ketone hydrogenation
catalyst may comprise a metal selected from Pt, Pd, Ru, Ni, Co, Mo,
Cr, Cu, Rh, and combinations thereof. In an embodiment, the
hydrogenation catalyst may further comprise a support material
selected from carbon, silica, magnesia, titania, and combinations
thereof. In a sub-embodiment, the hydrogenation catalyst may
comprise a metal selected from the group consisting of Pt, Pd, and
combinations thereof, and a support material selected from carbon,
silica, magnesia, titania, and combinations thereof.
[0045] In an embodiment, the ketone hydrogenation step may be
performed in the absence of a material that promotes dehydration of
the long chain secondary alcohol under the selective ketone
hydrogenation conditions used, so as to prevent or hinder ketone
conversion to the corresponding alkene or alkane, in order to
greatly increase the selectivity of ketone conversion to the long
chain secondary alcohol product. As a non-limiting example, the
selective ketone hydrogenation step may be performed in the absence
of alumina Alumina is used as a catalyst support in conventional
hydrotreating catalysts; however, processes as disclosed herein may
involve avoiding the presence of alumina during ketone
hydrogenation for the production of long chain secondary alcohols.
In an embodiment, alumina may be avoided during the ketone
hydrogenation step by using a selective ketone hydrogenation
catalyst that lacks an alumina component. Selective ketone
hydrogenation catalysts that lack alumina are described
hereinabove.
[0046] In an embodiment, the selectivity of long chain ketone
conversion to the corresponding long chain secondary alcohol via
the selective ketone hydrogenation step (e.g., according to Scheme
2) may be much higher, e.g., typically at least about 15% higher,
than that of comparable ketone hydrogenation in the presence of a
conventional hydrotreating catalyst comprising alumina. As a
non-limiting example, the selectivity of ketone conversion to the
corresponding long chain secondary alcohol by a selective ketone
hydrogenation catalyst as disclosed herein may be greater than
(>) 80% at 90% conversion, whereas the selectivity of ketone
conversion to the corresponding long chain secondary alcohol by a
conventional hydrogenation catalyst comprising an alumina support
is typically less than (<) 70% at 90% conversion.
[0047] In an embodiment, R.sub.1 and R.sub.2 in Schemes 1 and 2 may
each be linear or branched alkyl. In a sub-embodiment, R.sub.1 and
R.sub.2 may be independently selected from C.sub.5-C.sub.21 linear
or branched alkyl, or from C.sub.7-C.sub.17 linear or branched
alkyl, or from C.sub.9-C.sub.17 linear or branched alkyl, or from
C.sub.9-C.sub.15 linear or branched alkyl, or from
C.sub.15-C.sub.17 linear or branched alkyl. In an embodiment, the
at least one long chain secondary alcohol formed by ketone
hydrogenation, e.g., according to Scheme 2, may be in the range
from C.sub.11-C.sub.43, or from C.sub.21-C.sub.31, or from
C.sub.31-C.sub.35. In an embodiment, long chain secondary alcohols
prepared by processes as disclosed herein may comprise a mixture of
long chain secondary alcohols, e.g., each having from 11 to 43
carbon atoms per molecule. In an embodiment, each of the long chain
secondary alcohols may have the hydroxyl group placed at a
non-terminal location of the molecule. In a further embodiment, a
long chain secondary alcohol prepared according to embodiments of
processes disclosed herein may have the OH group placed at--or near
the center of the secondary alcohol molecule.
[0048] In an embodiment, fatty acid ketonization may comprise
contacting a mixture of at least two (2) fatty acids with the
ketonization catalyst in the ketonization zone. In an embodiment,
such a mixture of fatty acids may comprise a lipid mixture derived
from a source of lipids selected from a plant, an animal, or other
organism(s). Such sources of lipids may include, without
limitation, terrestrial plants, mammals, microorganisms, aquatic
plants, seaweed, algae, phytoplankton, and the like. In an
embodiment, a mixture of fatty acids for ketonization according to
processes as disclosed herein may be derived from palm kernel oil,
palm oil, coconut oil, corn oil, soy bean oil, rape seed (canola)
oil, poultry fat, beef tallow, and the like and their respective
fatty acid constituents, and combinations thereof.
[0049] In another embodiment, a process for preparing a long chain
secondary alcohol may comprise reacting a first fatty acid with a
second fatty acid to form a long chain ketone, and selectively
hydrogenating the long chain ketone to selectively form the
corresponding secondary alcohol. In an embodiment, the reacting
step and the ketone hydrogenating step may be jointly performed
according to the following Scheme 3.
##STR00009##
[0050] Scheme 3 combines or summarizes the reactions of Schemes 1
and 2 (supra) for embodiments wherein the fatty acid reactants for
ketonization are saturated. In an embodiment, each of m and n is an
integer in the range from 4 to 20, or from 8 to 16, or from 8 to
14, or from 14 to 16; wherein m and n may be equal or unequal such
that the first fatty acid and the second fatty acid may be the same
or different. In an embodiment, the reacting step may comprise
contacting the first fatty acid and the second fatty acid with a
ketonization catalyst in a ketonization zone under ketonization
conditions.
[0051] In an embodiment, the selectively hydrogenating step may
comprise contacting the long chain ketone with a selective ketone
hydrogenation catalyst in a ketone hydrogenation zone under
selective ketone hydrogenation conditions. In an embodiment, the
selective ketone hydrogenation catalyst will lack catalytic
activity for dehydration of the secondary alcohol, under the
selective ketone hydrogenation conditions used, such that ketone
conversion to the corresponding alkene or alkane is prevented. Due
to the relatively low reactivity of long chain ketones (e.g.,
C.sub.11-C.sub.43) in the ketone hydrogenation reaction, as
compared with lighter ketones (e.g., C.sub.3 or C.sub.4), the more
forcing conditions used for the long chain ketones would exacerbate
the negative effect that a hydrogenation catalyst having
dehydration functionality would have on product selectivity.
Instead, the use of a selective ketone hydrogenation catalyst that
at least substantially lacks dehydration activity, as disclosed
herein, allows for the efficient conversion of long chain ketones
with high selectivity to the corresponding long chain secondary
alcohols.
[0052] In an embodiment, exemplary conditions for selective ketone
hydrogenation may comprise a temperature in the range from 200 to
755.degree. F. (93 to 402.degree. C.), or from 355 to 755.degree.
F. (179 to 402.degree. C.), or from 400 to 750.degree. F. (204 to
399.degree. C.), a pressure in the range from 200 to 5000 psi, or
from 250 to 5000 psi, or from 300 to 4000 psi, a liquid hourly
space velocity (LHSV) in the range from 0.05 to 5.0 h.sup.-1, or
from 0.1 to 5.0 h.sup.-1, or from 0.5 to 4.0 h.sup.-1, and a
hydrogen to feed molar ratio in the range from 1.0 to 1000, or from
5.0 to 1000, or from 10 to 1000. In an embodiment, the
hydrogenation catalyst may comprise a metal selected from the group
consisting of Pt, Pd, Ru, Ni, Co, Mo, Cr, Cu, Rh, and combinations
thereof. In a sub-embodiment, the metal may be selected from Pt,
Pd, and combinations thereof.
[0053] As described hereinabove, the selective hydrogenation of
long chain ketones may be performed in the absence of a material
that promotes dehydration of the secondary alcohol under selective
ketone hydrogenation conditions, such that conversion to the
corresponding alkene or alkane is prevented or hindered.
Accordingly, the selective ketone hydrogenation catalyst will lack
a material, such as alumina, that promotes dehydration of the
secondary alcohol under said selective ketone hydrogenation
conditions. This is in contrast to conventional hydrotreating
catalysts having an alumina support that promotes alcohol
dehydration to alkenes, with subsequent hydrogenation to alkanes.
Advantageously, selective ketone hydrogenation as disclosed herein
allows the corresponding secondary alcohol to be obtained
efficiently with excellent selectivity.
[0054] In an embodiment, long chain secondary alcohol products)
prepared as disclosed herein may comprise a mixture of long chain
secondary alcohols and may be subjected to various separation
processes. Such separation may involve, for example, distilling
and/or flash distillation to provide one or more long chain
secondary alcohol products.
Distilling
[0055] In an embodiment, a step of distilling may employ one or
more distillation columns to separate the desired product(s) from
by-products. In an embodiment, the step of distilling may employ
flash distillation or partial condensation techniques to remove
by-products including at least low molecular weight materials.
Those of skill in the art will recognize that there is some
flexibility in characterizing the high and low boiling fractions,
and that the products may be obtained from "cuts" at various
temperature ranges.
EXAMPLES
Example 1
Ketonization of Lauric Acid to Laurone Using Alumina Catalyst
[0056] The ketonization of lauric acid to 12-tricosanone (laurone)
was catalyzed by an alumina catalyst operated in a fixed bed
continuously fed reactor at ambient pressure, at a temperature
range of 770-840.degree. C., and with a feed rate that gave a
liquid hourly space velocity (LHSV) of 0.62-0.64 h.sup.-1. The
conversion rate of lauric acid to laurone was calculated based on
the composition of the product as determined by GC analysis using
an FID detector.
[0057] The freshly loaded new alumina catalyst was calcined in the
reactor at 900.degree. F. (482.degree. C.) with a stream of dry
nitrogen (2 volumes of nitrogen per volume of catalyst per minute)
for 2 hours before the temperature was lowered to 770.degree. F.
(410.degree. C.), nitrogen was turned off and the lauric acid feed
was introduced. Product composition analysis showed that the fresh
catalyst operating at 770.degree. F., LHSV=0.62-0.64 h.sup.-1, gave
a lauric acid conversion of 62-66%.
Example 2
Hydrogenation of 12-Tricosanone to 12-Tricosanol Over a Pt/Carbon
Hydrogenation Catalyst
[0058] 12-tricosanone (laurone) prepared by ketonization reaction
of lauric acid over alumina catalyst was hydrogenated over a carbon
supported platinum catalyst to make the corresponding alcohol,
12-tricosanol.
[0059] 12-tricosanone was introduced as a liquid flow (4.1-4.4
g/hr, 12-13 mmoles/hr) together with hydrogen (100 Nml/min, 250
mmoles/hr) to a fixed reactor holding 7 ml of 0.5% Pt/carbon (3.5
g, particle size: 0.3-1 mm) The pressure was held at 1500 psi. The
liquid products were collected after the reaction and analyzed by
GC. The liquid product stream was found to contain three
components: unconverted 12-tricosanone and two products: the target
alcohol, 12-tricosanol, and the corresponding n-alkane,
n-tricosane, of which the latter was present only in trace
amounts.
[0060] At 450-470.degree. F. reaction temperature the GC analysis
of the product showed a conversion of 12-tricosanone of 80-87% and
a selectivity to 12-tricosanol of 98.9-99.4% with the remaining
0.6-1.1% being n-tricosane formed by hydro-deoxygenation of the
alcohol.
Example 3
Hydrogenation of Coconut Fatty Acid Derived Ketones to a Mixture of
Linear Secondary Alcohols
[0061] Saturated fatty acids from coconut oil contain a mixture of
C.sub.8-C.sub.14 fatty acids with C.sub.12 and C.sub.14 fatty acids
being the predominant components. Such a coconut fatty oil-derived
mixture of fatty acids were reacted under ketonization conditions
over alumina catalyst at 790-820.degree. F. and atmospheric
pressure to prepare a product mixture from which a mixture of
C.sub.19-C.sub.27 ketones with >90% ketones and less than 1%
unconverted fatty acids were isolated.
[0062] The above mentioned coconut-derived ketone mixture was
converted to the corresponding alcohols by hydrogenation over a
fixed bed of 0.5% Pt/carbon catalyst. Hydrogenation at 1500 psi
pressure and 450-460.degree. F. gave about 90% ketone conversion to
a mixture of the corresponding alcohols (80-90% selectivity) and
the corresponding alkanes (10-20% selectivity) based on GC analysis
of the mixed products. We expect that improved selectivity is
achievable through optimization of the reactor and flow
distribution.
Example 4
C.sub.29-C.sub.35 Linear Alcohols from Beef Tallow Fatty Acids
[0063] A saturated fatty acid mixture (Product TRT1655 from Twin
Rivers Technologies, Quincy, Mass.) prepared from beef tallow and
consisting predominantly of stearic acid (octadecanoic acid, about
45%) and palmitic acid (hexadecanoic acid, about 45%) with smaller
amounts of myristic acid (tetradecanoic acid, about 5%) and other
fatty acids was processed over an alumina catalyst at
800-810.degree. F. and atmospheric pressure to produce a reactor
effluent from which a product mixture of predominantly
C.sub.29-C.sub.35 ketones with less than 0.15 wt % fatty acids were
isolated.
[0064] This beef tallow-derived ketone mixture was hydrogenated
over a 0.5% Pt/carbon catalyst at 650.degree. F. and 1588 psi
hydrogen at a LHSV=0.48 h.sup.-1 to yield the corresponding
C.sub.29-C.sub.35 secondary alcohol mixture with a ketone
conversion of about 82% and a selectivity above 99%.
[0065] Long chain secondary alcohols prepared from inexpensive
feedstocks according to processes as disclosed herein may be
converted to a range of valuable products including lubricants.
Example 5
Comparative: Hydrogenation of Laurone Over Alumina Supported
Cobalt-Molybdenum Catalyst
[0066] 6 ml of an alumina supported cobalt-molybdenum catalyst was
loaded into a fixed bed reactor in its oxide form and activated as
follows. First the catalyst was dried by slow heating to
450.degree. F. where the temperature was held for 1 hr. (heating
rate: 100.degree. F./hr, nitrogen flow: 500 Nml/min, 100 psi).
After 1 hr of nitrogen treatment at 450.degree. F. hydrogen was
passed over the catalyst at a rate of 500 Nml/min at 100 psi,
450.degree. F. After 1 hr of hydrogen treatment the pressure was
increased to 800 psi and the catalyst was sulfided by treatment
with dimethyl disulfide solution in heptane. This treatment was
initially done at 450.degree. F., then gradually at increasing
temperature to 650.degree. F. and then at the latter temperature
for a couple of hours to ensure complete sulfidation.
[0067] The sulfided catalyst was cooled to 300.degree. F., laurone
(12-tricosanone) was introduced at a flow of 15 g/hr and
subsequently the temperature was adjusted to reaction
conditions.
[0068] At 350.degree. F., 1000 psi and 300 Nml/min hydrogen the
ketone conversion was found to be less than 25%.
[0069] The laurone feed flow was lowered to 8 g/hr, hydrogen flow
lowered to 150 Nml/min, the pressure raised to 1750 psi and the
temperature raised to 400.degree. F. At these conditions the
conversion was 92% but the selectivity to tricosanol was only 62%,
the remainder of the product being tricosane. Lowering the
temperature to 385.degree. F. improved the selectivity (82%
selectivity to tricosanol) but the ketone conversion was now only
58%.
[0070] It was concluded from the results in comparative Example 5
that, although we used a particularly active hydrogenation catalyst
and thus were able to hydrogenate the ketone at relatively low
temperature, the alumina support (a known dehydration catalyst)
still dehydrated sufficient of the alcohol to make unacceptably
large amounts of the alkane even at fairly low conversion.
Conceivably, a cobalt-molybdenum catalyst on a different support
may have better selectivity but this was not tested.
[0071] For the purposes of this specification and appended claims,
unless otherwise indicated, all numbers expressing quantities,
percentages or proportions, and other numerical values used in the
specification and claims, are to be understood as being modified in
all instances by the term "about." Furthermore, all ranges
disclosed herein are inclusive of the endpoints and are
independently combinable. Whenever a numerical range with a lower
limit and an upper limit are disclosed, any number falling within
the range is also specifically disclosed. Additionally, chemical
species including reactants and products designated by a numerical
range of carbon atoms include any one or more of, or any
combination of, or all of the chemical species within that
range.
[0072] Any term, abbreviation or shorthand not defined is
understood to have the ordinary meaning used by a person skilled in
the art at the time the application is filed. The singular forms
"a," "an," and "the," include plural references unless expressly
and unequivocally limited to one instance. All publications,
patents, and patent applications cited in this application are
incorporated by reference herein in their entirety to the extent
not inconsistent herewith.
[0073] Modifications of the exemplary embodiments disclosed above
may be apparent to those skilled in the art in light of this
disclosure. Accordingly, the invention is to be construed as
including all structure and methods that fall within the scope of
the appended claims. Unless otherwise specified, the recitation of
a genus of elements, materials or other components, from which an
individual component or mixture of components can be selected, is
intended to include all possible sub-generic combinations of the
listed components and mixtures thereof.
* * * * *