U.S. patent application number 10/157172 was filed with the patent office on 2003-12-04 for process for well fluids base oil via metathesis of alpha-olefins.
Invention is credited to Christensen, S. Alex, Hensey, Scott, Rost, William R., Twu, Fred Chun-Chien.
Application Number | 20030224945 10/157172 |
Document ID | / |
Family ID | 29582406 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030224945 |
Kind Code |
A1 |
Twu, Fred Chun-Chien ; et
al. |
December 4, 2003 |
Process for well fluids base oil via metathesis of
alpha-olefins
Abstract
Disclosed is a process for preparation of compositions having
utility as well fluid base oils. The process involves metathesis of
alpha-olefins followed by isomerization of the metathesis products.
The base oils resulting from the process of this invention are
environmentally friendly in that they are only mildly toxic to
marine life and have very low pour point temperatures. These
properties make the base oils ideal candidates for use as
components of well fluids for cold climates and offshore
applications.
Inventors: |
Twu, Fred Chun-Chien;
(Naperville, IL) ; Christensen, S. Alex;
(Northwoods, IL) ; Hensey, Scott; (West Chicago,
IL) ; Rost, William R.; (Montgomery, IL) |
Correspondence
Address: |
CAROL WILSON
BP AMERICA INC.
MAIL CODE 5 EAST
4101 WINFIELD ROAD
WARRENVILLE
IL
60555
US
|
Family ID: |
29582406 |
Appl. No.: |
10/157172 |
Filed: |
May 29, 2002 |
Current U.S.
Class: |
507/200 |
Current CPC
Class: |
C07C 2521/04 20130101;
C07C 5/2512 20130101; C07C 6/04 20130101; C07C 5/2518 20130101;
C07C 5/2708 20130101; C09K 8/34 20130101; C07C 2523/36
20130101 |
Class at
Publication: |
507/200 |
International
Class: |
E21B 001/00 |
Claims
We claim:
1. A process for production of valuable liquid products suitable
for use as at least one component in low pour point temperature and
low toxicity well fluid base oils comprising the steps of: (i)
providing a predominantly linear alpha-olefins feed wherein said
alpha-olefins have from about 4 to about 22 carbon atoms, (ii)
subjecting said feed to metathesis conditions in the presence of a
metathesis catalyst so as to form valuable liquid metathesis
products and gaseous ethylene as a by-product, (iii) separating the
valuable liquid metathesis products from the gaseous ethylene so as
to drive the reaction to completion and permit recovery of the
valuable liquid metathesis products, (iv) optionally, further
purifying the liquid metathesis products from step (iii), and (v)
subjecting a feed comprising about 10 to 100 weight percent of the
product selected from step (iii), step (iv) and mixtures thereof to
isomerization conditions in the presence of an isomerization
catalyst.
2. The process of claim 1 wherein the metathesis catalyst comprises
rhenium.
3. The process of claim 1 wherein the metathesis temperature is in
the range of about 10.degree. C. to about 150.degree. C.
4. The process of claim 1 wherein the gaseous ethylene by-product
is removed by deployment of an inert gas purge of the metathesis
reactor during the linear alpha-olefin metathesis
5. The product made by the process of claim 1.
6. A well fluid base oil comprising the product of claim 5.
7. A process for production of valuable liquid products suitable
for use as at least one component in low pour point temperature and
low toxicity well fluid base oils comprising the steps of: (i)
providing a predominantly linear alpha-olefins feed wherein said
alpha-olefins have from about 4 to about 22 carbon atoms, (ii)
subjecting said feed to metathesis conditions in the presence of a
heterogeneous supported metathesis catalyst so as to form valuable
liquid metathesis products and gaseous ethylene as a by-product,
(iii) separating the valuable liquid metathesis products from the
gaseous ethylene so as to drive the reaction to completion and
permit recovery of the valuable liquid metathesis products, (iv)
optionally, further purifying the liquid metathesis products from
step (iii), and (v) optionally, subjecting a feed comprising about
10 to 100 weight percent of the product selected from step (iii),
step (iv) and mixtures thereof to isomerization conditions in the
presence of an isomerization catalyst.
8. The process of claim 7 wherein the metathesis catalyst comprises
rhenium.
9. The process of claim 7 wherein the metathesis temperature is in
the range of about 10.degree. C. to about 150.degree. C.
10. The process of claim 7 wherein the gaseous ethylene by-product
is removed by deployment of an inert gas purge of the metathesis
reactor during the linear alpha-olefin metathesis.
11. The product made by the process of claim 7.
12. A well fluid base oil comprising the product of claim 7.
13. A process for production of specialty linear internal olefins
comprising the steps of: (i) providing a predominantly linear
alpha-olefins feed wherein said alpha-olefins have from about 4 to
about 22 carbon atoms, (ii) subjecting said feed to metathesis
conditions in the presence of a heterogeneous supported metathesis
catalyst so as to form valuable liquid specialty linear internal
olefins and gaseous ethylene as a by-product, (iii) separating the
valuable liquid specialty internal olefin products from the gaseous
ethylene so as to drive the reaction to completion and recover the
valuable liquid specialty internal olefin products, and (iv)
optionally, further purifying the liquid specialty internal olefins
metathesis products from step (iii).
14. The process of claim 13 wherein the metathesis catalyst
comprises rhenium.
15. The process of claim 13 wherein the metathesis temperature is
in the range of about 10.degree. C. to about 150.degree. C.
16. The process of claim 13 wherein the gaseous ethylene by-product
is removed by deployment of an inert gas purge of the metathesis
reactor during the linear alpha-olefin metathesis
17. The product made by the process of claim 13.
18. A well fluid base oil comprising the product of claim 17.
19. A lube oil additive comprising the product of claim 17.
20. A lube oil comprising the product of claim 17.
21. A lube oil comprising the hydrogenated product of claim 17.
22. A metal working lubricant comprising the product of claim
17.
23. A metal working lubricant comprising the hydrogenated product
of claim 17.
24. A component of a metal working fluid comprising the product of
claim 17.
25. A surfactant comprising product formed by chemically adding a
polar group to the product of claim 17.
26. An alkenyl succinic anhydride compound formed by chemically
reacting maleic anhydride with a feed comprising the product of
claim 17.
27. A plasticizer comprising the product of claim 17.
Description
RELATIONSHIP TO PRIOR APPLICATIONS
[0001] (Not Applicable)
STATEMENT REGARDING FEDERALLY FUNDED RESEARCH
[0002] (Not Applicable)
FIELD OF THE INVENTION
[0003] The invention relates generally to a process for making
compositions having utility as base oils for well fluids. The
multi-step process involves metathesis of alpha-olefins followed by
isomerization of the metathesis products. The base oils resulting
from the process of this invention are environmentally friendly and
have very low pour point temperatures. These properties make the
base oils ideal candidates for use as components of well fluids for
cold land drilling climates and also for cold offshore drilling
applications. The products formed by the metathesis portion of the
process (absent the isomerization step) are also valuable and have
utility (as produced) as components of lube oils, lube oil
additives, alkenyl succinic anhydrides, surfactants, and
plasticizers or as precursors to selected members of the preceding
list.
BACKGROUND OF THE INVENTION
[0004] Historically, first crude oils, then diesel oils and, more
recently, mineral oils have been used in formulating well fluids.
Due to problems of toxicity and persistence which are associated
with these oils, and which are of special concern for offshore use,
the industry is developing well fluids that are based on
"pseudo-oils". Examples of such oils are fatty acid esters and
synthetic hydrocarbons such as poly(alpha)olefins. Fatty acid ester
based oils have excellent environmental properties, but well fluids
made with these esters tend to have lower densities and are prone
to hydrolytic instability. Poly(alpha)olefin based well fluids can
be formulated to high densities, have good hydrolytic stability and
low toxicity. They are, however, somewhat less biodegradable than
esters, they are expensive and the fully weighted, high density
fluids tend to be overly viscous, especially when used in cold
climates. A most recent trend in the industry is the use of base
oils comprising predominantly linear internal olefins. The present
invention offers a new and novel metathesis route to liquid
internal olefins that have better toxicity properties than the
liquid internal olefins currently used in well fluid base oils.
Additionally, the internal olefins made by the process of this
invention also have very low pour point temperatures sufficient for
extreme cold and/or offshore drilling applications. There is a
continuing need for improved well fluid base oils that are
environmentally acceptable and have pour point temperatures in the
range of about -15.degree. C. to about -40.degree. C. The present
invention addresses this need via a process that includes a
metathesis reaction followed by an isomerization of the product
prepared by metathesis.
INVENTION SUMMARY AND REVIEW OF PRIOR ART
[0005] The present invention resides in a process for the
preparation of compositions that are especially favorable for use
as well fluid base oils. The well fluid base oils prepared by the
process of this invention are not only environmentally acceptable
but also have especially advantageous and unexpectedly low pour
point temperatures.
[0006] The base oil compositions of this invention are prepared by
a process that involves at least one chemical reaction. For the
purposes of this disclosure, alpha olefin is intended to mean a
mono-olefin having the carbon-carbon double bond after the terminal
(first) carbon atom. In the first (metathesis) reaction, an
alpha-olefin feed is provided and then subjected to metathesis
conditions. The linear alpha-olefin feed to the metathesis process
is not 100 percent linear alpha-olefins. A more precise feed
definition will be recited later. Other materials are typically
present in the feed. A non-exhaustive listing of such other
materials includes internal olefins, vinylidene olefins,
tri-substituted olefins, and branched (non-linear) olefins. The
linear alpha-olefin (or mixture of several linear alpha-olefins)
feed is subjected to metathesis conditions in the presence of a
metathesis catalyst. Linear alpha-olefins having an integer number
of carbon atoms in the range of about 4 to about 22 are envisioned
as suitable for the metathesis feed. In the metathesis step, the
linear alpha-olefins react with one another to form linear internal
olefins. If only one linear alpha-olefin having n carbon atoms
(where n is an integer in the range of 4 to 22) is subjected to
metathesis (known as self-metathesis), then the product formed will
be a linear internal olefin having (2n-2) carbon atoms with the
double bond at the center position, i.e., after carbon atom n. If a
mixture of several linear alpha-olefins is subjected to metathesis
(known as cross-metathesis), then several linear internal olefin
products are formed, all of which will have the double bond at an
internal position. If the shortest alpha-olefin fed to metathesis
has 4 carbons, then the internal olefins formed from metathesis
will have the double bond at least after or even more internal than
carbon atom No. 3.
[0007] The centralized double bond olefins of self metathesis and
the internal olefins of cross metathesis are valuable chemical
compositions and substances that have important commercial
applications other than as a component of well fluid base oils.
When used for preparation of well fluid base oils, the base oils
are found to have lower toxicity than base oils comprised of
currently used internal olefins. The pour point temperatures of
well fluid base oils made from these metathesis liquids are useful
in cold climates. In some applications, such as extremely cold land
or offshore drilling, it is desirable to have even lower pour point
temperatures than those exhibited by the metathesis liquids.
Applicants have found that an unexpectedly large change in pour
point temperature can be achieved by isomerizing the liquid
products from the self and/or cross metathesis process. The
isomerization is conducted under isomerization conditions and in
the presence of a catalyst which is typically used for olefin
isomerization, including both (1) migration of the double bond
within the olefin molecule, and (2) skeletal rearrangement of the
olefin molecule. Surprisingly, when used as well fluid base oils,
the metathesized and isomerized liquids retain or improve their
salient environmental characteristics and, in the process, produce
well fluid base oils having pour point temperatures about
15.degree. C. to 40.degree. C. lower than those obtained absent the
isomerization step.
[0008] U.S. Pat. No. 5,589,442 (Gee et al.) discloses well fluid
base oil which is predominantly unbranched (linear) internal
olefins. The Gee et al. patent discloses the use of C.sub.12 to
C.sub.24 olefins in their mixture, preferably C.sub.14-C.sub.18
olefins. The disclosure of the Gee et al. patent permits the
presence of some branched olefins in their mixtures (0-50 wt %)
with the remainder being linear olefins. The disclosure of the Gee
et al. patent also permits the presence of some alpha olefins in
their mixture (0-20 wt %) with the remainder being internal
olefins. The pour point temperature of the preferred embodiment of
the Gee et al. disclosure is -5.degree. C. with some formulations
having pour point temperatures as low as -9.degree. C. This
application may be differentiated from the disclosure of U.S. Pat.
No. 5,589,442 in that it is directed to production of well fluid
base oil having pour point temperatures in the range of -15.degree.
C. to -30.degree. C. with an especially preferred embodiment having
a pour point temperature of -36.degree. C. Also, the liquids
produced by the process of this disclosure have improved toxicity
properties over those disclosed in the Gee et al. reference.
[0009] U.S. Pat. Nos. 5,741,759, 6,057,272 (both also Gee et al.),
6,323,157 (Carpenter et al.), and the Gee et al. '442 patent
referenced above all disclose the use of commercially available
linear alpha olefin or linear alpha olefin mixtures in the range
C.sub.14 to C.sub.18 as the starting material for their base oil
according to the examples in these references. These are then
transformed into internal olefins for use in well fluid base oils.
Alpha olefins in this carbon count range are extremely valuable as
compared to alpha olefins in the range of C.sub.4 to C.sub.12.
Applicants' process discloses the use of these lower carbon chain
alpha olefins as starting materials to produce internal olefin, for
example, in the range C.sub.14 to C.sub.18 thus offering a
substantial commercial advantage over the disclosure of the four
references cited above.
[0010] A PCT patent application published as patent document WO
01/46096 discloses a process for production of drilling fluid made
from metathesis products of C.sub.4 to C.sub.10 olefins.
Applicants' disclosure may be distinguished from this reference as
follows: (1) applicants metathesis is conducted in the presence of
a heterogeneous catalyst system as opposed to the homogeneous
system of this reference, (2) applicants use a rhenium metathesis
catalyst system, and in a preferred embodiment, as opposed to the
metathesis catalyst metals disclosed by this reference, and (3)
applicants perform metathesis followed by isomerization whereas
there is no isomerization step disclosed in WO 01/46096,
[0011] An article in "Chem. Eng. Prog.", 1979, V 75, No. 1, Pages
73-76 entitled SHELL'S HIGHER OLEFINS PROCESS (SHOP) by authors
Freitas and Gum discloses a four-step process aimed at production
of internal olefins in the range useful for detergents manufacture.
The steps in the SHOP process are (1) ethylene oligomerization to
produce an alpha-olefin, (2) purification of alpha-olefins to
remove catalyst poisons, (3) isomerization of the alpha-olefin to
produce internal olefin, and (4) disproportionation (aka
metathesis) to form the desired chain length internal olefins.
Applications disclosure may be distinguished from this reference in
a number of different ways including: (A) applicants' process is
directed to metathesis first followed by isomerization instead of
isomerization followed by disproportionation and (B) the source of
the metathesized alpha-olefins forms no part, per se, of
Applicants' disclosed process.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] It should be noted that the term "comprising" is used
frequently throughout the description of this invention and also in
the appended claims. "Comprising", as used in this application and
the appended claims is defined as "specifying the presence of
stated features, integers, steps, or components as recited, but not
precluding the presence or addition of one or more other steps,
components, or groups thereof". Comprising is different from
"consisting of", which does preclude the presence or addition of
one or more other steps, components, or groups thereof.
[0013] For the purposes of this invention, a well fluid is intended
to be any fluid or near fluid used in the rotary method of drilling
wells, chiefly for gas and oil, and is not intended to be
restricted only to so-called drilling muds. A non-limiting list of
well fluids includes drilling muds, spotting fluids, lubricating
additives, and other products for the treatment of subterranean
wells. Also, for the purposes of this invention, internally
isomerized olefins are defined to comprise olefins having only a
single double bond (mono-olefin) joining adjacent carbon atoms
other than the terminal (or alpha) carbon atom of the carbon chain.
Mixtures of internal olefin isomers implies that several different
double bond isomers are present, e.g., some of the olefins may have
a double bond connecting carbon atom #8 to carbon atom #9, some
double bonds may connect carbon atom #7 to carbon atom #8, etc. For
each double bond isomer, generally, there will be at least two
stereo isomers commonly referred to as the cis and trans forms.
Mixtures of internal olefin isomers may also imply the presence of
both linear (unbranched) and branched olefin isomers.
[0014] The present invention relates to a group of synthetic liquid
hydrocarbons and to well fluids based on them, especially to well
fluids which are useful in the rotary drilling process used for
making wells into subterranean formations containing oil, gas or
other minerals.
[0015] The rotary drilling process is used for making wells for the
production of oil, gas and other subterranean minerals such as
sulfur. In rotary drilling operations, a drill bit at the end of a
drill string is used to penetrate the subterranean formations. This
drill bit may be driven by a rotating drill string or a drill motor
powered, for example, by hydraulic power. During the rotary
drilling operation, a fluid, conventionally referred to as a
drilling mud, is circulated from the drilling equipment on the
surface down to the drill bit where it escapes around the drill bit
and returns to the surface along the annular space between the
drill bit and the surrounding subsurface formations. The drilling
mud lubricates the down-hole equipment and serves as a carrier to
bring the formation cuttings to the surface where they can be
separated from the mud before it is recirculated. In addition, the
drilling mud serves to counterbalance formation pressures and may
also form a cake around the walls of the borehole to seal the
formations.
[0016] The lubricating action of the drilling mud is particularly
important with the conventional rotating drill string since it
provides a lubricant or cushion between the rotating drill pipe and
the walls of the borehole, helping to prevent sticking of the drill
string in the hole. The characteristics and performance of drilling
muds are described, for example, in Kirk-Othmer, Encyclopedia of
Chemical Technology, Third Edition, John Wiley and Sons, 1982,
under Petroleum (Drilling Muds). This reference discloses a
description of drilling muds and the materials used in formulating
them.
[0017] Drilling muds are usually classified as either water based
muds or oil-based muds, depending upon the character of the
continuous phase of the mud, although water-based muds may contain
oil and oil-based muds may contain water. Water-based muds
conventionally comprise a hydratable clay, usually of the
montmorillonite family, suspended in water with aid of suitable
surfactants, emulsifiers and other additives including salts, pH
control agents and weighting agents such as barite. The water makes
up the continuous phase of the mud and is usually present in any
amount of at least 50 volume percent of the entire composition. Oil
is also usually present in minor amounts but will typically not
exceed the amount of the water so that the mud will retain its
character as a water-continuous phase material. Oil-based muds
generally use a hydrocarbon oil as the main liquid component with
other materials such as clays or colloidal asphalts added to
provide the desired viscosity together with emulsifiers, gellants
and other additives including weighting agents. Water may be
present in greater or lesser amounts but will usually not be
greater than 50 volume percent of the entire composition. If more
than about 10 weight percent water is present, the mud is often
referred to as an invert emulsion, i.e. a water-in-oil emulsion. In
invert emulsion fluids, the amount of water is typically up to
about 40 weight percent with the oil and the additives making up
the remainder of the fluid. Under appropriate conditions, the well
fluid base oils of the present invention may comprise any of the
above-described materials, i.e., water-based fluids, oil-based
fluids, and invert emulsion fluids.
[0018] Historically, oil-based muds were conventionally formulated
with diesel oil or kerosene as the main oil component as these
hydrocarbon fractions generally possess the requisite viscosity
characteristics. They do, however, possess the disadvantage of
being relatively toxic to marine life and the discharge of drilling
muds containing these oils into marine waters is usually strictly
controlled because of the serious effects that the oil components
may have on marine organisms. The control is particularly acute for
marine life that are commercially important as food. For this
reason, offshore drilling rigs must return oil-based muds to shore
after they have been used whereas water-based muds may generally be
discharged into the ocean without any deleterious effects.
[0019] Oil-based muds may be formulated to be environmentally
acceptable by the use of oils that possess low inherent toxicity to
marine organisms and good biodegradability. These properties are
more generally found in hydrocarbons with low aromaticity. For
these reasons, well fluids based on paraffins might be considered
desirable. On the other hand, linear paraffins tend to have high
pour point temperatures and the higher molecular weight fractions
tend to be waxy so that in the low temperature environments
frequently encountered in offshore drilling, there is a significant
risk that waxy paraffin deposits will be formed in the down hole
equipment or in the riser connecting the sea bed to the drilling
equipment. In either event, this is unacceptable with the result
that highly paraffinic oils have not achieved any significant
utility as bases for well fluids.
[0020] The use of olefins as base oils for well fluids represents
yet another way to avoid the toxicity associated with the use of
aromatics in well fluid base oils and has become a pursued
alternative in recent years. Linear alpha and internal olefins have
all found application as components of well fluid base oils. The
present invention is directed, in part, to a process for production
of well fluid base oils comprising intermediate to long chain
(predominantly unbranched) internal olefins. In this context,
predominantly unbranched is intended to mean at least 50 weight
percent.
[0021] The linear alpha-olefin feed that is subjected to
self-metathesis or cross metathesis will generally include olefins
in the range having from about 4 to about 22 carbon atoms.
Preferably, the range will be from about 6 to about 20 carbon
atoms, and most preferably from about 8 to about 18 carbon atoms.
For this invention, the linear alpha-olefin feed is defined to be
at least 90% (by weight) linear alpha-olefin for olefins in the
range of about 4 to about 12 carbon atoms. The linear alpha-olefin
feed is further defined to be at least 70% (by weight) linear
alpha-olefin for olefins in the range of about 13 to about 20
carbon atoms. The linear alpha-olefin feed is defined to be at
least 45% (by weight) linear alpha-olefin for olefins having more
than 20 carbon atoms. A non-exhaustive list of other materials
which may be present in the linear alpha-olefin feed include
internal olefins (branched or linear), vinylidene olefins,
tri-substituted olefins, and branched (non-linear) alpha-olefins.
The self or cross metathesis transforms the linear alpha-olefin
feed into predominantly linear internal olefins. For the purpose of
this invention, a linear deep internal olefin is defined to be a
linear olefin that has its double bond in the range of after carbon
atom 3 or further toward the center of the molecule. According to
this definition (at least for this invention) there will be no deep
internal olefins having fewer than 6 carbon atoms.
[0022] Reaction 1, as given below, shows a self-metathesis
reaction, for the desired or main reaction, in generic form.
1-C.sub.nH.sub.2n (n-1)-C.sub.(2n-2)H.sub.(4n-4)+C.sub.2H.sub.4
Reaction 1
[0023] In Reaction 1, the substance 1-C.sub.nH.sub.2n is a normal
(unbranched) 1 olefin (alpha-olefin), n is an integer and has a
value in the range of about 4 to about 22, C.sub.2H.sub.4 is
ethylene, and (n-1)-C.sub.(2n-2)H.sub.(4n-4) is a linear
(unbranched) internal olefin with the double bond after carbon atom
(n-1), i.e., the double bond is directly in the middle of the
compound. In actuality, it would require two moles of reactant to
produce a mole of ethylene and a mole of desired metathesis product
as shown in Reaction 1. For the sake of simplicity, balancing the
mass in Reaction 1 has been omitted. For the range of carbon atoms
envisioned and the metathesis conditions for this invention,
ethylene will exist as a gas and the desired valuable metathesis
product will be a liquid.
[0024] According to the well-known textbook entitled "Olefin
Metathesis and Metathesis Polymerization" by Ivin and Mol, Academic
Press, 1997, PP. 1, "The metathesis reactions are generally
reversible and, with the right catalyst system, equilibrium can be
attained in a matter of seconds, even with substrate/catalyst
ratios of 104; a truly remarkable reaction." Thus it is seen that
metathesis reactions are catalytic reactions and, very importantly,
equilibrium limited. This means that reaction is typically not
complete but results in a final equilibrium mixture of reactants
and products. Therefore, in the case of Reaction 1, for this
invention the ethylene by-product (which is gas) is removed from
the reaction vessel. The ethylene may be removed by use of an inert
gas purge, by operating the reaction at reduced pressure, or a
combination of vacuum and inert gas purge to remove the ethylene
gas. For this purpose, inert gas is defined as a gas that does not
participate in the metathesis reactions. Suitable inert gases
include, but are not limited to, nitrogen, steam, carbon dioxide,
straight chain alkanes (e.g. methane, ethane, propane, butane,
etc.) and branched alkanes (e.g. isobutane, etc). Nitrogen is the
preferred purge gas. As will be seen in the Examples section of
this application, removal of the ethylene serves to shift the
reaction equilibrium to favor the desired product, which drives the
reaction to completion. In practice, this operation also serves as
means to separate the desired liquid metathesis product from the
ethylene by-product. Removal of the ethylene and driving the
reaction to completion also obviates the need for recycle of
un-reacted product for further processing.
[0025] For metathesis understanding purposes only, it is useful to
envision that the linear feed alpha-olefin molecule is "cut" into
two fragments at the double bond, a one-carbon fragment and an
(n-1) carbon fragment. Again, for further understanding only, it
may be envisioned that the one carbon fragment can recombine with
an (n-1) carbon fragment forming a double bond at the combination
point and regenerating the original feed linear alpha-olefin
molecule. An alternative and desired possibility is for two (n-1)
fragments to combine forming the desired metathesis internal
olefin. When two one carbon fragments combine, ethylene is
formed.
[0026] Some further insight into self-metathesis may be gained by
reviewing specific examples. Reaction 2 and Reaction 3 below
indicate the self-metathesis of linear (normal) 1-decene to
9-octadecene and linear (normal) 1-nonene to 8-hexadecene
respectively.
1-C.sub.10H.sub.20 9-C.sub.18H.sub.36+C.sub.2H.sub.4 Reaction 2
1-C.sub.9H.sub.18 8-C.sub.16H.sub.32+C.sub.2H.sub.4 Reaction 3
[0027] Again, for the sake of simplicity, balancing the mass in
Reactions 2 and 3 has been omitted. It is obvious from these two
examples that the internal olefin formed from self-metathesis of a
linear alpha-olefin always has an even number of carbon atoms
regardless of whether an odd or even number carbon atom
alpha-olefin is self-metathesized. Also, the double bond is always
located exactly in the center of the internal olefin formed, i.e.,
after carbon atom 9 for C.sub.18 and after carbon atom 8 for
C.sub.16.
[0028] As previously mentioned, the metathesis feed may be
comprised of two or more linear alpha-olefins. Applicants refer to
this process as cross-metathesis. Reaction 4 below indicates the
situation that would prevail for cross-metathesis when the feed
comprises two linear alpha-olefins.
1-C.sub.nH.sub.2n+1-C.sub.mH.sub.2m
(n-1)-C.sub.(2n-2)H.sub.(4n-4)+(m-1)--
C.sub.(2m-2)H.sub.(4m-4)+(m-1)-C.sub.(m+n-2)H.sub.(2m+2n-4)+C.sub.2H.sub.4
Reaction 4
[0029] As in the previous reactions, the mass in Reaction 4 is not
balanced for the sake of simplicity. In Reaction 4, n and m are
integers in the range of 4 to 22, are not equal to each other, and
m has a lower value than n. As was the case for self-metathesis,
C.sub.2H.sub.4 is ethylene. For the range of carbon atoms
envisioned and the metathesis conditions of this invention,
ethylene will exist as a gas and the desired cross-metathesis
products will be liquid. In practice, the ethylene gas is easily
removed serving to drive the reaction to completion and also
serving as means to separate the desired and more valuable liquid
metathesis products from the ethylene by-product.
[0030] A specific example, showing the cross metathesis of 1-decene
and 1-nonene, is given by Reaction 5.
1-C.sub.10H.sub.20+1-C.sub.9H.sub.18
9-C.sub.18H.sub.36+8-C.sub.16H.sub.3-
2+8-C.sub.17H.sub.34+C.sub.2H.sub.4 Reaction 5
[0031] As before, the mass is not balanced in Reaction 5. The
cross-metathesis of 1-decene with 1-nonene yields some 9-octadecene
and some 8-hexadecene as was the case for the separate
self-metathesis of these two linear alpha-olefins. However, a new
product, 8-heptadecene (C.sub.17), is also formed by combination of
an 8-carbon atom fragment with a 9-carbon atom fragment. Because
8-heptadecene has an odd number of carbons atoms, it is not
possible for the double bond in this internal linear olefin to be
at the very center of the molecule.
[0032] Cross metathesis of feeds comprising three different
alpha-olefins would lead to production of six liquid internal
olefin metathesis products plus ethylene. In a similar manner, it
can be calculated that cross metathesis of feeds comprising four
different alpha-olefins would lead to production of ten liquid
internal olefin metathesis products. Cross metathesis of feeds
comprising two, three, or more than three different alpha-olefins
leading to wide varieties of liquid internal olefin metathesis
products is also envisioned to be within the scope of this
invention.
[0033] Having now considered cross metathesis in more detail, it is
necessary to briefly reconsider self-metathesis. This will be done
by further consideration of the self-metathesis of 1-decene as
given by Reaction 2 where the desired product is 9-C.sub.18H.sub.36
and the by-product is ethylene. The (unwanted) presence of 2-decene
subjected to metathesis will provide for the presence of some
C.sub.8 and some C.sub.2 molecule fragments. These unwanted
fragments could combine with some of the many C.sub.9 fragments
present to form 8-C.sub.17H.sub.34 and 2-C.sub.11H.sub.22. This
side reaction is undesirable and can be prevented, or at least
minimized, by reducing the amount of 2-decene present. The 2-decene
may be present in the metathesis reactor because it was present in
the metathesis feed. Therefore, feed quality and purity of the
1-decene of Reaction 2 may be important for certain applications.
The second source of 2-decene in the metathesis reactor is from the
isomerization of 1-decene to 2-decene. The presence of 2-decene
from isomerization may be controlled by selection of the proper
metathesis catalyst formulation to one which prohibits the
isomerization of 1-decene to 2-decene. In part, this may be
accomplished by choice of the metathesis catalyst support. The
support should have only minimal acidic sites so as discourage
1-decene isomerization. Processes for making very low or acidic
neutral alumina support are well known in the art. Applicants have
found that use of gamma-alumina as the support provides good
results. Often, the same objective may be achieved by making metals
of Groups VIA, VIIA, and their oxides part of the metathesis
catalyst system.
[0034] The self and cross metathesis of the C.sub.4 to C.sub.22
linear alpha-olefins may be conducted in batch or continuous mode.
The metathesis may be done in single reactors, plural reactors in
series or parallel, and via up flow or down flow of materials.
Generally the metathesis is conducted via a fixed bed catalyst
process with heterogeneous catalyst. The catalyst composition will
comprise about 2 to about 20 percent by weight catalyst metal or
metal oxide and the remainder will be comprised of support. The
preferred support is alumina. Especially preferred is gamma
alumina. The preferred weight percent catalyst metal or metal oxide
is from about 5 to 15 weight percent, and especially preferred is
about 10 weight percent catalyst metal or metal oxide and about 90
weight percent support. The suitable metathesis catalyst metal or
metal oxide catalysts include any transition metal or metal oxide
from the Groups VIB (Cr, Mo, W), VIIB (Mn, Tc, Re), and VII (Ru,
Co, Pt, Pd, Fe, Ni, Ir, Os) or any combination of them. Preferred
metal or metal oxide catalysts are Re, W, Mo, and Co, or
combinations of them. Especially preferred is Re and/or Re
oxides.
[0035] The metathesis is carried out under relatively mild reaction
conditions in an effort to prevent or at least minimize
isomerization of the alpha-olefin feed and metathesis products once
formed. Generally the reactor temperature will be maintained in the
range of about 0.degree. C. to about 150.degree. C. The preferred
reactor temperature is in the range of about 20.degree. C. to about
110.degree. C. The residence time in the reactor will run from as
little as about fifteen minutes to as much as about 12 hours. The
preferred residence time in the reactor is from about 0.5 hour to
about 6 hours.
[0036] As in any other process, the desired effect for the self and
cross metathesis is a high conversion rate and a high rate of
selectivity to the desired metathesis product or products. The
by-product of the metathesis reactions is ethylene. Ethylene exists
as a gas and the desired metatheses products are liquid at the
reaction conditions recited above. Therefore, it is a relatively
simple process to separate the desired liquid product from the
gaseous by-product, ethylene. Removal of the gaseous by-product
ethylene helps to drive the metathesis reaction to completion.
Removal of the ethylene gas may be accomplished by continuously
purging the reactor with an inert gas, such as nitrogen. The
reaction pressure is generally maintained at about one atmosphere,
but reactor pressures in the range of 0.1 to about 5.0 atmospheres
are suitable. An alternative method for enhanced separation of
ethylene from the desired liquid metathesis is to operate the
reaction at pressures below 1.0 atmosphere so as to accelerate the
removal of the ethylene.
[0037] The degree of selectivity of the metathesis reaction
depends, at least in part, on the purity of the alpha-olefin feed
provided. The linear alpha-olefin feed was previously defined. The
feed covers olefins having in the range of about 4 to about 22
carbon atoms. As previously noted, the nature and purity of the
feed varies, to some extent, based on the carbon count of the
olefin in the metathesis feed. Especially unwanted in the feed are
excess amounts of branched (non-linear) alpha-olefins that will
lead to production of branched metathesis products. Also, excess
amounts of internal olefins in the metathesis feed will lead to
mixed metathesis products and also to short carbon chain
by-products other than ethylene. The branched and internal olefins
in the feed may be a result of isomerization of the feed during the
metathesis. The short carbon chain by-products may not be entirely
gaseous which will affect conversion rate at well as product
purity. Another factor in determining selectivity is the mild
reaction conditions employed. It is important to minimize
isomerization of the liquid metathesis product prior to removal
from the reactor. This undesired isomerization may take the form of
migration of the double bond to a position further from the center
of the internal olefin molecule. Another undesired isomerization is
branching of the linear internal olefins formed by the metathesis
reaction. Yet another isomerization of the metathesis product to be
avoided is formation of tri-substituted olefins. Thus, in addition
to mild conditions, it is also extremely important to select a
metathesis catalyst that is essentially inactive in terms of
isomerization of the liquid metathesis products or the feed.
[0038] The linear internal olefin metathesis products are very
valuable liquids. Well fluid base oils comprised of these liquids
have pour points of about 0.degree. C. and are environmentally
friendly in that they exhibit very low toxicity toward marine life.
While not wishing to be bound by theory, applicants speculate that
the low pour point temperature of well fluids comprising these
liquids may be due to the extreme and deep internal olefin isomers
produced by the metathesis process, to the lack of branching, and
also due to the extreme homogeneity of the product. Applicants have
no ready answer to the reason for their low toxicity to marine
life. It is now recognized that unsaturated fats having excess
trans isomer may pose a threat to humans at least equal to that
posed by saturated fats. Perhaps the distribution of cis and trans
isomers produced by the metathesis process may also explain, at
least in part, the reason for the low toxicity of these fluids to
marine life.
[0039] In practice, formulations of well fluid base oils comprising
these liquid metathesis products will be further comprised of many
additional substances including typical well fluid base oil
additives and additive packages. In certain instances, and
sometimes simply for the sake of convenience or available materials
or as a means to reduce the cost of the base oils, other materials
may contribute a portion of formulations comprising these base
oils. Additional and/or optional materials may be included only to
the extent that the resulting base oils maintain their two salient
features of (1) pour point temperatures in the range of about
0.degree. C., or lower and (2) low toxicity to marine life.
[0040] Other components of the well fluid base oils comprising the
liquid metathesis products may include linear alpha-olefins in the
range about 8 to 20 carbon atoms, mixtures of these linear
alpha-olefins, linear internal olefins in the range of about 8 to
20 carbon atoms, mixtures of these internal olefins, and mixtures
involving at least two of the preceding. If present as a component
in the well fluid base oils, the linear alpha-olefins may be formed
by any known process (including dehydration of normal alcohols) and
their method of production forms no part, per se, of the present
invention. If present as a component in the well fluid base oils,
the linear internal olefins may be formed by any known process and
their method of production forms no part, per se, of the present
invention. Known processes for production of internal linear
olefins is intended to include metathesis products of olefins other
than as disclosed above and also is intended to include olefins
which originated from any know process. Such known processes
include but are not limited to the following: (1) dehydration of
alcohols, (2) dehydrohalogenation of halogenated hydrocarbons, (3)
cracking of aliphatic hydrocarbons, (4) dehydration of alkanes or
paraffinic hydrocarbons including hydroforming reactions, (5)
conversion of esters to alcohols and acids followed by dehydration
reactions, (6) oligomerization of lower carbon number (e.g.,
ethylene, propylene, butene, pentene, hexene) olefins, and (7)
Fischer-Tropsch reactions (catalytic reactions of carbon monoxide
and hydrogen via iron or cobalt containing catalysts).
[0041] The liquid metathesis products also find utility as
precursors to surfactants. Upon addition of a polar group (e.g.,
sulfonate, sulfate, acid, amine, amine oxide, oxide, etc.) via
known chemical processes to the deep internal olefin liquid
metathesis products, a surfactant with enhanced oil solubility
emerges. The enhanced oil solubility is with respect to addition of
a similar polar group to an alpha-olefin or to a conventionally,
internally isomerized linear alpha-olefin. The enhanced oil
solubility of the polarized liquid metathesis products allow use of
the surfactant in lower concentration to effectively lower the
interfacial surface tension of the oil as well as improve the
surfactant's emulsifying and dispersant properties. Such benefits
are useful in light and heavy-duty surfactant applications.
Additionally, these surfactants should be able to absorb oil from a
marine oil spill without wave action or agitation.
[0042] The valuable liquid metathesis products also find utility as
a precursor component of lube oils. Typically, the liquids products
of the metathesis would be hydrogenated and then used as a
component of lube oils. The valuable liquid metathesis products
also find utility as a precursor component and/or as a component in
the production of lube oil additives.
[0043] The liquid metathesis products also find utility as a
precursor to alkenyl succinic anhydride (ASA) compounds. ASA
compounds are used extensively in the papermaking industry as a
paper-sizing additive for improving properties of paper, including
fine paper and gypsum board. Commercial sizing agents based on ASA
compounds are typically prepared from the reaction products of
C.sub.14 to C.sub.22 olefins and maleic anhydride. The properties
of the olefins used in this reaction have a major influence on the
sizing performance of the resulting ASA compounds in the paper
sizing process. Specifically, ASA compounds prepared from maleic
anhydride and C.sub.16 internal olefins, C.sub.18 internal olefins
and mixtures of C.sub.16 and C.sub.18 internal olefins are among
the more preferred ASA compounds. The liquid metathesis products
provide exceptional performance when used in the formation of ASA
compounds. The unique structural characteristics of the liquid
metathesis products such as the amount and type of internal olefins
impart properties to the resulting ASA that provide excellent
sizing performance.
[0044] The liquid metathesis products also find utility in
lubricant compositions as metalworking fluids, cutting oils, and
quench oils. The lubricity and physical properties of the liquid
metathesis products are useful characteristics in lubricating oil
compositions for metal fabrication such as cold metal and alloy
metal forming applications and other metal-working operations such
as blanking, bending, stamping, rolling, forging, punching,
pressing, forming and drawing processes. The high boiling point of
some liquid metathesis products such as those formed by the
self-metathesis of 1-decene (boiling point 162.degree. C.) or those
forming compounds with higher carbon numbers provide a useful
feature by allowing a higher maximum workable die temperature. The
low toxicity and environmentally friendly characteristics of the
liquid metathesis products may be useful in metalworking fluid
applications requiring direct food contact. As a component of a
metalworking fluid, the liquid metathesis products may assist in
the cutting, grinding, or forming of metal and function to improve
the lifetime and fabrication precision of the tool and improve
productivity of the process.
[0045] In addition to specific applications for the liquid
metathesis products made by the process disclosed above, the
disclosed metathesis process also provides a convenient method for
the manufacture of specialty linear internal olefins from linear
alpha-olefins essentially on a made to order, custom basis. For
example, suppose a need existed for manufacture of the rather
unusual compound, linear internal olefin 3-hexadecene
(3-C.sub.16H.sub.32). This compound could easily be prepared in
high purity by the metathesis process disclosed above. According to
Reaction 4, which governs cross metathesis of two alpha-olefins, it
would be necessary to cause a feed comprising linear 1-butene
(1-C.sub.4H.sub.8) and linear 1-tetradecene (1-C.sub.14H.sub.28) to
cross metathesis under metathesis reaction conditions. According to
Reaction 4, three metathesis products would be formed in addition
to by-product gaseous ethylene. These three metathesis products
would be 3-hexene (3-C.sub.6H.sub.12), the C.sub.26 internal olefin
13-C.sub.26H.sub.52, and also 3-hexadecene (3-C.sub.16H.sub.32),
the desired internal olefin. The gaseous ethylene by-product is
separated from the three liquid metathesis products. The separation
may be easily accomplished by purging with an inert gas. Removal of
the gaseous by-product ethylene also helps to drive the reaction to
further completion. The desired product, 3-hexadecene, may be
easily isolated and purified from the other liquid products by
distillation or other separation and purification processes well
known in the art. Other liquids present, if any, may optionally be
recycled as feed or otherwise recovered.
[0046] In a similar manner, the linear internal olefin 5-hexadecene
would be prepared from cross metathesis of 1-hexene with 1-dodecene
(1-C.sub.12H.sub.24). The linear internal olefin 4-hexadecene would
be prepared from cross metathesis 1-pentene with 1-tridecene
(1-C.sub.13H.sub.26). The linear internal olefin 6-hexadecene would
be prepared from cross metathesis 1-heptene (1-C.sub.7H.sub.14)
with 1-undecene (1-C.sub.11H.sub.22). The linear internal olefin
7-hexadecene would be prepared from cross metathesis 1-octene
(1-C.sub.8H.sub.16) with 1-decene (1-C.sub.10H.sub.20). The linear
internal olefin 8-hexadecene would be prepared from self-metathesis
of 1-nonene. Thus, all of the deep internal linear hexadecene
olefins (3 or 4 or 5 or 6 or 7 or 8-hexadecene) could be prepared
Via the metathesis process disclosed above. In a similar manner,
most of the internal tetradecenes, pentadecenes, heptadecenes,
octadecenes, etc. could be prepared by self or cross metathesis of
the appropriate linear alpha-olefin feed as disclosed. The range of
specialty linear internal olefins that can be prepared is extremely
wide. The substance linear 9-tricosene (9-C.sub.23H.sub.46) could
be prepared by cross metathesis of 1-decene with 1-pentadecene. The
substance linear 15-triacontene (15-C.sub.30H.sub.60) could be
prepared from self-metathesis of 1-hexadecene.
[0047] Surprisingly, applicants have found that the pour point
temperatures of well fluid base oils comprising the liquid
metathesis products could be lowered by an additional 15.degree. C.
to 40.degree. C. by further isomerization of the liquid metathesis
products. In many instances, only partial isomerization may be
necessary to achieve the benefit of pour point temperature
depression. This pour point temperature improvement is obtained
without sacrifice of the excellent toxicity properties of the well
fluid base oils comprising the metathesis liquids. In practice this
is achieved by subjecting the metathesis product to internal
isomerization conditions in the presence of an internal
isomerization catalyst. Generally the feed for the isomerization
step will be comprised of the metathesis product in the range of at
least about 10 weight percent to about 100 weight percent of the
isomerization process feed. Preferably the isomerization feed will
be comprised of metathesis product in the range of about 50 weight
percent to about 100 weight percent. Most preferably the
isomerization feed will be comprised of metathesis product in the
range of about 70 weight percent to about 90 weight percent. Other
components of the isomerization feed may include linear
alpha-olefins in the range about 8 to 20 carbon atoms, mixtures of
these linear alpha-olefins, linear internal olefins in the range of
about 8 to 20 carbon atoms, mixtures of these internal olefins, and
mixtures involving at least two of the preceding. If present in the
isomerization feed, the linear alpha-olefins may be produced by any
known process (including dehydration of normal alcohols) and the
process for producing them forms no part, per se, of the present
invention. If present in the isomerization feed, the linear
internal olefins may be produced by any known process and the
process for producing them forms no part, per se, of the present
invention. Known processes for production of internal linear
olefins is intended to include metathesis processes other than as
disclosed above and also is intended to include olefins which
originated from dehydration of alcohols.
[0048] The isomerization conditions employed for the feed
comprising the metathesis process liquids are also rather mild.
Typical temperatures employed in the isomerization reactor are in
the range of about 50 to about 350.degree. C. The preferred
temperature range is from about 100 to about 300.degree. C. The
isomerization catalyst is selected from the group consisting of any
solid catalysts containing Bronsted and/or Lewis acid sites. These
catalysts include the heterogeneous catalysts (or combination of at
least two of them) such as commercially available or developmental
catalysts, HY-zeolite, H-ZSM-5, Theta-1 (or ZSM-22), supported PMA
(phosphomolybdic acid), supported HPW (phosphotungstic acid), pure
or halogenated alumina or magnesia, silica-alumina, Group VIII
metals on alumina, phosphate-containing alumina or magnesia,
Amberlyst (ion-exchange resin, A-35D or A-15D), sulfated zirconia,
Nafion, SAPO-11, SAPO-34, etc. The preferred isomerization
catalysts are alumina, H-ZSM-5, Nafion, and Theta-1. Pressures
employed during the isomerization range from about 1 atmosphere to
about 50 atmospheres.
[0049] Both the metathesis and isomerization portions of the
process can be practiced with fixed bed reactors, via up or down
flow mode, with one reactor or multiple reactors, in cyclic mode
(e.g. one or more in operation, one in purging, one in
regeneration), and with one-pass through or with recycle.
Regeneration of the catalyst can be accomplished by using dry air
or diluted air to burn off coke, followed by re-oxidation of the
metal in the metathesis catalyst followed by purging with inert
gases. The regeneration off-gas can also be recycled to save
cost.
[0050] A major use for these isomerized internal olefins is as a
component in formulations of well fluid base oils. When well fluid
base oils are formulated comprising the product of the
isomerization process disclosed above, it is found that the well
fluid base oils retain, and often improve, their salient property
of low toxicity to marine life. However, the pour points of the
resulting well fluid base oils has been lowered by as much as about
40.degree. C. to absolute pour point temperatures of about
-36.degree. C. In practice, formulations of well fluid base oils
comprising these internal isomerization products will be further
comprised of many additional substances including typical well
fluid base oil additives and additive packages. In certain
instances, sometimes simply for the sake of convenience or
available materials or as a means to reduce the cost of the base
oils, other materials may contribute a portion of formulations
comprising these base oils. Additional and/or optional materials
may be included only to the extent that the resulting base oils
maintain their two salient features of (1) pour point temperatures
in the range of about -15.degree. C. and as low as -36.degree. C.
and (2) low toxicity to marine life.
[0051] In one major embodiment, this invention is directed to a
process for production of valuable liquid products suitable for use
as at least one component in low pour point temperature and low
toxicity well fluid base oils comprising the steps of:
[0052] (i) providing a predominantly linear alpha-olefins feed
wherein said alpha-olefins have from about 4 to about 22 carbon
atoms,
[0053] (ii) subjecting said feed to metathesis conditions in the
presence of a metathesis catalyst so as to form valuable liquid
metathesis products and gaseous ethylene as a by-product,
[0054] (iii) separating the valuable liquid metathesis products
from the gaseous ethylene so as to drive the reaction to completion
and permit recovery of the valuable liquid metathesis products,
[0055] (iv) optionally, further purifying the liquid metathesis
products from step (iii), and
[0056] (v) subjecting a feed comprising about 10 to 100 weight
percent of the product selected from step (iii), step (iv) and
mixtures thereof to isomerization conditions in the presence of an
isomerization catalyst.
[0057] In another embodiment, this invention is directed to a
process for production of valuable liquid products suitable for use
as at least one component in low pour point temperature and low
toxicity well fluid base oils comprising the steps of:
[0058] (i) providing a predominantly linear alpha-olefins feed
wherein said alpha-olefins have from about 4 to about 22 carbon
atoms,
[0059] (ii) subjecting said feed to metathesis conditions in the
presence of a heterogeneous supported metathesis catalyst so as to
form valuable liquid metathesis products and gaseous ethylene as a
by-product,
[0060] (iii) separating the valuable liquid metathesis products
from the gaseous ethylene so as to drive the reaction to completion
and permit recovery of the valuable liquid metathesis products,
[0061] (iv) optionally, further purifying the liquid metathesis
products from step (iii), and
[0062] (v) optionally, subjecting a feed comprising about 10 to 100
weight percent of the product selected from step (iii), step (iv)
and mixtures thereof to isomerization conditions in the presence of
an isomerization catalyst.
[0063] In yet another preferred embodiment, this invention is
directed to a process for production of specialty linear deep
internal olefins comprising the steps of:
[0064] (i) providing a predominantly linear alpha-olefins feed
wherein said alpha-olefins have from about 4 to about 22 carbon
atoms,
[0065] (ii) subjecting said feed to metathesis conditions in the
presence of a heterogeneous supported metathesis catalyst so as to
form valuable liquid specialty linear internal olefins and gaseous
ethylene as a by-product,
[0066] (iii) separating the valuable liquid metathesis products
from the gaseous ethylene so as to drive the reaction to completion
and permit recovery of the valuable liquid metathesis products,
[0067] (iv) optionally, further purifying the liquid specialty
internal olefins metathesis products from step (iii).
EXAMPLES
Preparation of Catalysts A, B and C
[0068] Catalysts used in all examples, except as noted, were
prepared as follows:
[0069] Catalyst A: A standard nominal 10 weight percent
rhenium-y-alumina (gamma-alumina) catalyst was prepared by
completely dissolving NH.sub.4ReO.sub.4 in water at 85.degree. C.
The NH.sub.4ReO.sub.4 solution of NH.sub.4ReO.sub.4 was used to
wet-impregnate .gamma.-alumina powder (80-100 mesh). This was
followed by drying with air at 200.degree. C. for about 120
minutes, calcining in air at 525.degree. C. for about 180 minutes,
and finally cooling under N.sub.2 to room temperature.
[0070] Catalyst B: A standard nominal 10 weight percent
rhenium-.gamma.-alumina (gamma-alumina) catalyst was prepared by
completely dissolving NH.sub.4ReO.sub.4 in water at 85.degree. C.
The solution of NH.sub.4ReO.sub.4 was used to wet-impregnate
.gamma.-alumina quadrlalobe extrudate (0.1 cm (0.04 inch)
quadralobe extrudate). A quadralobe extrudate is only one of
several suitable choices. The purpose and intent is to maximize the
surface area of the catalyst and still maintain its crush strength.
Other suitable catalyst extrudate shapes would include trilobe,
hollow cylinder, doughnut, star, and CDS. The wet-impregnated
extrudate was then dried with air at 200.degree. C. for about 120
minutes, calcined in air at 525.degree. C. for about 300 minutes,
and finally cooled to room temperature under nitrogen gas.
[0071] Catalyst C: Prepared in the same manner as Catalyst A,
except that boric acid was also dissolved in the NH.sub.4ReO.sub.4
solution so as to comprise 2 weight percent of the final catalyst
formulation.
[0072] Catalyst handling was conducted in a dry box where nitrogen
was used as a blanket and oxygen level in the dry box was always
maintained well below 100 ppm. The 1-decene metathesis reactions
were conducted in glass reactors, which typically contained 3 grams
of Catalyst A with 40 ml (or 30 grams) of decene liquid resulting
in 0.1 to 1 weight ratio of Re catalyst to 1-decene feed. Untreated
decene was the feed received as 1-decene from the BP Pasadena, Tex.
LAO plant. Treated 1-decene was obtained by treating the BP
Pasadena, Tex. 1-decene with a basic alumina powder in order to
remove impurities such as water, alcohols, and oxygenated
compounds. Before treating the 1-decene feed, the basic activated
alumina, (Aldrich 19,944-3) was first treated in a Muffle furnace
(in air) at 250.degree. C. for 16 hours. The 1-decene pretreatment
then was conducted under nitrogen blanketing.
Examples 1-5
[0073] In a glass slurry reactor a magnetic stirrer constantly
agitated the reactor mixture so the 1-decene liquid and Catalyst A
were in good contact during the one-hour reaction. Mineral oil bath
provided homogeneous heating to the reactor, typically set at
60.degree. C. A septum on top of the reactor prevented the reaction
mixture from contacting ambient air or moisture. For
non-equilibrium operations during the reaction, nitrogen was
introduced into contact with the reaction mixture through a
syringe. A mass flow meter was always used to monitor the flow rate
of the reaction off-gas in ml/min. Gas chromatography was used to
analyze the 1-decene feed and the reaction products. Percent
conversion of 1-decene was calculated by subtracting the weight %
1-decene in the product mixture from that in the feed, dividing by
the amount in the feed, and then multiplying by 100. Selectivity
was calculated by dividing the sum of the weight of C16, C17 and
C18 olefins in the product mixture by the total weight of all the
compounds present (other than 1-decene) in the product mixture, and
then multiplying by 100. The ethylene gas was not included in the
selectivity calculation.
[0074] The objective was to maximize the main, and desired,
metathesis reaction (as given by Reaction 6) at 60.degree. C. with
Re catalysts. 1
[0075] Two types of side, and undesired, reactions were also
observed: (I) isomerization of 1-decene, which reduces selectivity,
and (II) the reaction of ethylene with other olefins, which reduces
conversion and selectivity.
[0076] (I) Isomerization reactions can occur because of the acidic
sites on the catalyst surface to form internal decene isomers prior
to metathesis. For example, isomerization of 1-decene forms
2-decene, which can then react with the 9-octadecene to form
2-C.sub.11H.sub.22 and 8-C.sub.17H.sub.34 internal olefins.
Isomerization of 1-decene and 2-decene also forms 3-decene, which
can react with 9-octadecene to form 3-C.sub.12H.sub.24 and
7-C.sub.16H.sub.32 internal olefins. If present, 4-decene can react
with 9-octadecene to form 4-C.sub.13H.sub.26 and 6-C.sub.15H.sub.30
internal olefins. The 2.5 weight % branched compounds in the
1-decene feed such as the vinylidenes, 2-ethyl-octene-1 (2EO1) and
2-butyl-hexene-1 (2BH1), are readily catalytically isomerized into
their respective trisubsubstituted species. Four compounds are
formed by the isomerization of 2EO1. These are trans and cis forms
of 3-methyl-3-nonene and trans and cis forms of 3-methyl-2-nonene.
Four compounds are formed by the isomerization of 2BH1. These are
trans and cis forms of 5-methyl-5-nonene and trans and cis forms of
5-methyl-4-nonene.
[0077] These unwanted isomerization reactions are difficult to
control except by using catalyst containing minimal acidic sites.
The catalysts used for these examples were supported on a
non-acidic (i.e., neutral) alumina support, thereby causing only
minimal isomerization of 1-decene.
[0078] (II) Small amount of dissolved ethylene gas formed by the
main self-metathesis reaction can react with any olefins to form
other olefin molecules. For example, ethylene can react
catalytically with any decene isomers such as internals and
vinylidenes to cleave olefins at the double bond to form olefins
with different carbon numbers. Although ethylene exists in very
small amounts, its reactions reduce selectivity and conversion of
the main reaction.
[0079] The use of nitrogen gas to purge the gaseous and unwanted
ethylene by-product also serves to drive the reaction to
completion. Examples 1-5 described in Table 1 below serve to show
this inventive aspect for the self metathesis of 1-decene using
Catalyst A with treated 1-decene feed at a reactor temperature of
60.degree. C., reactor residence time of 60 minutes, and a Re to
1-decene ratio of 0.1
1TABLE 1 Examples 1-5 Self-metathesis of 1-decene Ex. N.sub.2 Feed
Conversion Selectivity No. Purge Volume Percent Percent 1 No 40 ml
77.1 92.2 2 No 30 ml 79.4 91.1 3 No 200 ml 77.0 91.6 4 Yes 40 ml
90.7 94.7 5 Yes 40 ml 93.4 95.8
[0080] These data show that, with Catalyst A, both conversion and
selectivity in the self-metathesis of 1-decene are improved by
purging the reaction mixture with nitrogen. The percent conversion
and the selectivity percent are calculated as recited above.
[0081] The use of nitrogen gas to purge the gaseous and unwanted
ethylene by-product also serves to drive the reaction to completion
when used with a modified Catalyst A. Modified Catalyst A was
improved over Catalyst A by lengthening the impregnation time and
using 70-100 mesh .gamma.-alumina. Examples 6-7 described in Table
2 below serve to show this inventive aspect for the self metathesis
of 1-decene using modified Catalyst A with treated 1-decene feed at
a reactor temperature of 60.degree. C., reactor residence time of
60 minutes, and a Re to 1-decene ratio of 0.1
2TABLE 2 Examples 6-7 Ex. N.sub.2 Feed Conversion Selectivity No.
Purge Volume Percent Percent 6 No 40 ml 75.2 93.6 7 Yes 40 ml 94.2
97.8
[0082] These data show that, with modified Catalyst A, both
conversion and selectivity in the self-metathesis of 1-decene are
improved by purging the reaction mixture with nitrogen. The percent
conversion and the selectivity percent are calculated as recited
above.
[0083] As comparative examples, Applicants tested Catalyst C for
self-metathesis of 1-decene. Recall that Catalyst C is the same as
Catalyst A except that it also is comprised of 2 weight percent
boric acid. Catalyst C, with its acidic sites, would be predicted
to be a better isomerization catalyst than Catalyst A. Comparative
Examples 7-10 in Table 3 below serve to show that a use of a
nitrogen purge no longer improves conversion and selectivity for
the self metathesis of 1-decene using acid site Catalyst C with
treated 1-decene feed at a reactor temperature of 60.degree. C.,
and a Re to 1-decene ratio of 0.1.
3TABLE 3 Examples 7-10 Catalyst C-self-metathesis of 1-decene Ex.
N.sub.2 Feed Reaction Conversion Selectivity No. Purge Volume Time
Percent Percent 7 No 40 ml 30 min. 75.3 24.8 8 Yes 40 ml 30 min.
77.0 25.9 9 No 40 ml 60 min. 91.0 26.3 10 Yes 40 ml 60 min. 89.9
27.5
[0084] It can be seen that with 30 minutes reactor time (Ex. 8) and
60 minutes reactor time (Ex. 10), the conversion level was
essentially not affected by the nitrogen purge when using an acid
catalyst. Applicants believe this is because of the high
isomerization activity of Catalyst C. For further understanding, a
gas chromatography analysis of the feed and reaction mixture is
shown for Examples 9 and 10 in Table 4 below.
4TABLE 4 Examples 9 & 10 GC Analysis of Feed and Products
Example No. 9 & 10 9 10 Analysis of 1-Decene Feed Reaction
Mixture Reaction Mixtjure Catalyst C C N.sub.2 Purge No Yes
Material 1-Decene Feed Reaction Mixture Reaction Mixture Analyzed
wt % wt % wt % Lights (<C8) 0.51 0.666 C.sup.=8 0.44 2.077
C.sup.=9 0.98 0.34 0.87 C10 unk. 1 0.11 0.095 0.088 C10 unk. 2 0.04
0.044 0.041 Butyl Branched 0.59 0.166 0.15 Ethyl Branched 0.89 0.28
0.21 1-Decene 94.88 8.71 9.74 3, 4, & 5-C.sup.=10 0.12 16.49
13.25 Decane 0.29 0 0 C-2-Decene 1.08 24.03 21.04 T-2-Decene 0.59
23.02 21.29 C11-unk. 1 0.77 3.00 C11 unk. 2 0.30 0.81 C.sup.=12
0.21 0.32 C.sup.=13 0.089 0.194 C.sup.=14 0.082 0.21 C.sup.=15
0.217 0.40 C.sup.=16 0.956 1.63 C.sup.=17 1.39 3.17 9-C.sup.=18
21.764 20.624 C.sup.=18 other 0.051 0.18 C.sup.=19+ 0.04 0.031
Total, % 99.6 99.99 99.99 Selectivity to C16-18, % 26.3 27.5
Conversion, % 91.0 89.9
[0085] In Table 4, unk. Indicates an unknown substance that was
found and C.sup.= indicates an olefin. At 60 minutes residence
time, (Examples 9 and 10), the conversion level was essentially not
affected by nitrogen purging yet the selectivity to C16-18 was
unusually low. This was due to the high isomerization activity of
1-decene, as shown in the Table 4. Note that the combined C.sub.10
internals, (cis and trans 2-decene) formed was over 55% with
nitrogen purging and over 63% with no purging. Since the
isomerization reactions of 1-decene are undesired reactions that do
not produce ethylene gas, the total conversion and selectivity
cannot be improved by purging with nitrogen when using an acid
(isomerizing) catalyst.
Examples 11-21
[0086] When subjected to isomerization conditions in the presence
of an olefin isomerization catalyst, the metathesis liquids
obtained using Catalyst A or Catalyst B acquire some unique and
especially salient properties. The data of Table 5 show the unique
properties obtained by using Catalyst B extrudates for
self-metathesis of 1-decene followed by isomerization of the
self-metathesis product of 1-decene. The metathesis was conducted
using a continuous flow reactor with nitrogen gas flowing
concurrently with the 1-decene feed. The ratio of nitrogen purge
flow to 1-decene was 1.5 g nitrogen to 1 g 1-decene. The beginning
reactor temperature was 40.degree. C., the WHSV was 1, and a
pressure of 1 atmosphere was employed. The initial conversion rate
for fresh catalyst was always 90% with high selectivity (95-97%
without accounting for ethylene). As the catalyst deactivates the
conversion fell to .about.75% at which time reactor temperature was
increased to raise conversion rate but selectivity was always
maintained at about the the same level. The metathesis reactor
product was collected and then distillation was conducted at 100-mm
Hg pressure to separate the 9-octadecene product from unconverted
1-decene feed. For Examples 11 to 21, the specific isomerization
conditions employed were dependent on the isomerization catalyst
deployed and are as listed in Table 5 below.
[0087] For purposes of comparison, Table 6 shows some physical
properties of 1-octadecene, and the 9-octadecene produced by
self-metathesis of 1-decene (Example 11). It can be seen that the
boiling point of 9-octadecene is higher and the melting point is
lower which makes 9-octadecene a liquid over a very long
temperature range.
5TABLE 5 Examples 11-21 Properties of 9-octadecene and isomerized
9-octadecene Example 11 12 13 14 15 16 17 18 19 20 21 Species 9-C18
C18IO C18IO C18IO C18IO C18IO C18IO C18IO C18IO C18IO C18IO
Isomerization N/A Al.sub.2O.sub.3 Al.sub.2O.sub.3 Theta-1 Theta-1
Theta-1 PMA PMA PMA HZSM5 A-35D Catalyst /TiO2 /TiO2 /TiO2 (T2559)
Isomerization N/A 220 300 200 220 220 200 220 220 220 100 Temp.
.degree. C. Isomerization N/A 2 1 2 1 2 2 1 2 2 2 Time, hours
Vinyl, wt % 0.0 0.0 0.0 0.0 0.0 0.51 0.80 0.79 0.67 0.5 0.54
Internal, wt % 99.37 96.3 99.74 65.9 52.6 41.1 89.2 90.6 91.4 91.3
63.6 Trisubs, wt % 0.61 2.9 2.3 33.2 46.2 55.9 9.8 8.5 7.7 7.9 35.5
Vinylidenes, 0.02 0.1 0.0 0.9 1.27 2.5 0.21 0.17 0.21 0.3 0.37 wt %
CH.sub.3/olefin 2.02 2.1 2.1 2.6 3.1 3.6 2.15 2.13 2.2 2.11 3.34
CH.sub.2/olefin 13.74 14.1 14.2 14.6 15.6 16.1 14.1 14.0 14.2 13.9
19.9 C.sub.ave/olefin 17.76 18.2 18.4 19.3 20.7 21.7 18.25 18.13
18.4 18.0 25.2 Melt. Pt., .degree. C. -30.5 -- Pour Pt, .degree. C.
0 0 -18 -21 -30 -36 -12 -12 -15 -15 -15 V, 0.degree. C., cSt -- --
9.6 11.9 13.7 17.2 10.6 10.4 10.6 10.1 26.0 V, 4.4.degree. C., cSt
-- -- 8.4 10.2 11.8 -- 9.3 9.1 -- -- -- V, 40.degree. C., cSt 3.4
3.6 3.5 4.0 4.4 5.0 3.7 3.7 3.7 3.6 7.0 V, 100.degree. C., cSt 1.40
1.46 1.43 1.56 1.66 1.80 1.49 1.49 1.49 1.45 2.29 Trans/Cis 78/22
75/25 69/31 Keys to Table 5: (1) 9-C18 is 9-octadecene; C18IO is
isomerized 9-octadecene; (3) Vinyl wt % is the amount of
alpha-olefin, i.e., CH.sub.2.dbd.CHC.sub.16H.- sub.33 as determined
by NMR; (4) Internal wt % is the amount of internal olefin where
double bond is not in alpha position as determined by NMR, (one
hydrogen on each double bond carbon atom, cis or trans); (5)
Trisubs. wt % is the amount of trisubstituted internal olefin,
i.e., only one hydrogen total # on both double bond carbon atoms as
determined by NMR; (6) Vinylidenes wt % is the amount of vinylidene
olefins (two hydrogens on one of the double bond carbon atoms and
two alkyl groups on the other double bond carbon atom); (7)
CH.sub.3/olefin is number of methyl groups per olefin molecule; (8)
CH.sub.2/olefin is the number of methylene groups per olefin
molecule; (9) C.sub.ave/olefin is the average number of carbon
atoms per olefin # molecule; (10) pour point was determined by the
method of ASTM D-97; (11) viscosities were determined by method of
ASTM D-445
[0088]
6TABLE 6 Comparison of 1-octadecene and 9-octadecene Species normal
1-octadecene 9-octadecene (Example 11) B.P. (at 8 mmHg) .degree. C.
145 162 Melting Point, .degree. C. 17.5 -30.5 Refractive Index
1.4478 1.4470 (.eta..sub.D. 20.degree. C.) Density, g/cc 0.7891
0.7916
[0089] Table 7 below characterizes the composition of selected
examples.
7TABLE 7 Characterization of Examples 11, 13, 22, and 23 Ex. No.
Characterization 11 The self-metathesis product of 1-decene using a
rhenium comprising metathesis catalyst. 13 The product formed by
isomerization of Example 11 (the metathesis product) using an
Al.sub.2O.sub.3 isomerization catalyst. 22 A commercial synthetic
olefin fluid intended for use as a major component of well fluid
base oils available from BP Corporation sold under the trade name
of Amodrill .RTM.. 23 A blend consisting of 15 weight percent of
Example 11 and 85 weight percent of Amodrill .RTM. (Example
22).
[0090] Table 8 below lists some properties of for these selected
examples, especially those properties that are significant in terms
of use of these liquids in well fluid base oils.
8TABLE 8 Properties of Examples 11, 13, 22, and 23 Example Number
11 13 22 23 metathesis catalyst Re Re N/A Re weight percent linear
99.4 97.7 70.6 75.0 pour point, .degree. C. 0 -18 -18 -21 viscosity
40.degree. C., cSt 11,279 12,305 6,245 8,134 Ref. Std. Toxicity,
mg/kg 8136 5763 5743 5763 Toxicity Ratio 0.63 0.43 0.78 0.62
Toxicity PASS/FAIL PASS PASS PASS PASS
[0091] In Table 8, viscosity at 40.degree. C. was measured by the
method of ASTM D-445 and pour point was measured by the method of
ASTM D-97. As can be appreciated, all of the examples in Table 8
have outstanding toxicity characteristics. The pour point of
Example 11 was 0.degree. C. before isomerization but dropped to
-18.degree. C. after isomerization (Example 13). The isomerization
process also caused the toxicity ratio to drop from 0.63 to 0.43.
Obviously the process of this invention, metathesis followed by
isomerization, produces liquids with extremely salient
properties.
[0092] It can be seen from the data in Table 8 that the
9-octadecene produced by metathesis and isomerized 9-octadecene
products have a unique combination of physical and environmental
characteristics for use as well fluid base oils. The viscosity of
these products is sufficiently low to be favored as well fluid base
oils. The pour point of the 9-octadecene product and especially the
isomerized 9-octadecene product are very useful in cold climates or
offshore drilling conditions. The toxicity of the 9-octadecene,
isomerized 9-octadecene, Amodrill.RTM., and the mixture containing
15% of the 9-octadecene and 85% Amodrill.RTM. were measured using
ASTM method E1367-99 test protocol as required in the U.S. EPA
NPDES (National Pollution Discharge Elimination System) General
Permit for New and Existing Sources and New Dischargers in the
Offshore Subcategory of the Oil and Gas Extraction Category for the
Western Portion of the Outer Continental Shelf of the Gulf of
Mexico. This protocol uses leptocheirus plumulosus in a 10-day
sediment toxicity test using a reference standard C1618 internal
olefin having approximately 65% C16 and 35% C18 olefin. A passing
result in this test protocol is indicated by a toxicity ratio value
of the LC.sub.50 values less than 1.0 as calculated by Equation 1:
1 Toxicity Ratio = 10 - day L C 50 ( standard ) 10 - day L C 50
fluid + ( 0.2 .times. 10 - day L C 50 ( standard ) ) Equation 1
[0093] The data in Table 8 illustrate the significant reduction in
toxicity of the 9-octadecene products compared with the reference
standard. All of the metathesis products listed in Table 8 are
significantly less toxic than the reference standard. A reduction
in toxicity is also illustrated by a 15% metathesis product blend
containing 85% Amodrill.RTM.. Data for Amodrill.RTM. are also
listed in Table 8 to illustrate relative toxicity values for
typical internal olefin products currently used as well fluid base
oils in oil and gas well drilling applications.
Example 24
[0094] Example 24 was done to illustrate the cross-metathesis
embodiment of the inventive process. For Example 24, 1-octene and
1-decene were subjected to cross-metathesis in a manner similar to
previous examples of self-metathesis of 1-decene. Experimental
conditions were: 10 grams of catalyst A in a tubular fixed bed
reactor with upflow of the continuous liquid feed, feed was 30 wt %
1-octene and 70 wt % 1-decene, 1.0 WHSV (weight hourly space
velocity), co-current nitrogen purging using 1.5 g N.sub.2 per g of
liquid feed, and a metathesis reactor temperature of 40.degree. C.
The reactor product sample was taken after 24 hours of reaction
time. The resulting compositions are given in Table 9 below.
9TABLE 9 Cross Metathesis of 1-octene and 1-decene Feed, Product,
Species wt % wt % light gases 0 10 C2 to C7 olefins C8 olefins 30
2.9 C10 olefins 70 6.5 C11 olefins 0 0.3 C12 olefins 0 0.1 C13
olefins 0 0.3 C14 olefins 0 7.9 C15 olefins 0 2.5 C16 olefins 0
32.9 C17 olefins 0 1.8 C18 olefins 0 34.8 Totals 100 100
[0095] Conversion of 1-octene and 1-decene was 90% and 91%,
respectively. The product contains light gases and olefins other
than the desired C.sub.14 to C.sub.18 olefins. These unwanted
olefins are present in minor quantities and probably as a result of
ethenolysis, and unwanted metathesis and cross-metathesis. The
selectivity to the desired C.sub.14 to C.sub.18 range olefins was
an outstanding 88%.
[0096] Reasonable variation and modification are possible in the
scope of the foregoing disclosure, the examples, and the appended
claims to this invention, the essence of which is that valuable
liquid products are formed by mild metathesis of linear
alpha-olefins of carbon count C.sub.4 to C.sub.22. Well fluid base
oils comprising these liquids are non-toxic to marine life and have
low temperature pour points in the range of about 0.degree. C.
Subjecting these liquids to isomerization conditions in the
presence of an isomerization catalyst further enhances the
properties of well fluid base oil comprising them in that the pour
point temperatures are decreased an additional 15.degree. C. to
40.degree. C. and the toxicity characteristics are also
improved.
* * * * *