U.S. patent application number 10/668933 was filed with the patent office on 2004-06-24 for process for making a linear alpha-olefin oligomer using a heat exchanger.
Invention is credited to Arnoldy, Peter, De Boer, Eric Johannes Maria, Moene, Robert, Unger, Phillip Edward, Van Zon, Arie.
Application Number | 20040122269 10/668933 |
Document ID | / |
Family ID | 32043228 |
Filed Date | 2004-06-24 |
United States Patent
Application |
20040122269 |
Kind Code |
A1 |
Van Zon, Arie ; et
al. |
June 24, 2004 |
Process for making a linear alpha-olefin oligomer using a heat
exchanger
Abstract
The invention pertains to a process for making a linear
alpha-olefin oligomer in a reactor comprising a liquid and a gas
phase, comprising the steps of catalytically oligomerizing ethylene
in the presence of an iron complex of a 2,6-bis(arylimino)pyridine
derivative, to an alpha-olefin oligomer under release of heat, and
removing the heat with a heat exchanger, which is not in direct
contact with the liquid phase, using at least part of the gas phase
as a coolant medium. The invention further relates to an apparatus
to perform said process.
Inventors: |
Van Zon, Arie; ( Amsterdam,
NL) ; Moene, Robert; (Amsterdam, NL) ; Unger,
Phillip Edward; (Houston, TX) ; Arnoldy, Peter;
(Amsterdam, NL) ; De Boer, Eric Johannes Maria;
(Amsterdam, NL) |
Correspondence
Address: |
Donald F. Haas
Shell Oil Company
Legal - Intellectual Property
P.O. Box 2463
Houston
TX
77252-2463
US
|
Family ID: |
32043228 |
Appl. No.: |
10/668933 |
Filed: |
September 23, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60413278 |
Sep 25, 2002 |
|
|
|
Current U.S.
Class: |
585/521 ;
422/198; 422/600 |
Current CPC
Class: |
C07C 2531/22 20130101;
C07C 2531/12 20130101; B01J 2208/00274 20130101; B01J 31/1815
20130101; B01J 2531/0244 20130101; B01J 31/143 20130101; B01J
2208/00256 20130101; B01J 2208/00247 20130101; B01J 8/1836
20130101; B01J 2208/00212 20130101; B01J 2219/00076 20130101; C08F
10/00 20130101; B01J 2531/842 20130101; C08F 10/00 20130101; B01J
8/22 20130101; C07C 2/32 20130101; C07C 2531/14 20130101; C08F
110/02 20130101; C08F 10/00 20130101; C08F 2/14 20130101; C08F 2/01
20130101; B01J 2231/20 20130101 |
Class at
Publication: |
585/521 ;
422/198; 422/189 |
International
Class: |
F28D 001/00 |
Claims
We claim:
1. A process for making a linear alpha-olefin oligomer in a reactor
comprising a liquid and a gas phase, comprising the steps of
catalytically oligomerizing ethylene in the presence of an iron
complex of a 2,6-bis(arylimino)pyridine derivative, to an
alpha-olefin oligomer under release of heat, and removing the heat
with a heat exchanger which is not in direct contact with the
liquid phase, using at least part of the gas phase as a coolant
medium.
2. The process of claim 1 wherein an aluminum-based co-catalyst is
added to the liquid phase.
3. The process of claim 2 wherein the aluminum-based co-catalyst is
an aluminoxane selected from the group consisting of methyl
aluminoxane, alkyl-modified methyl aluminoxane, and mixtures
thereof.
4. The process of claim 3 wherein the aluminum-based co-catalyst is
a methyl aluminoxane.
5. The process of claim 1 wherein the oligomer is an alpha-olefin
oligomer with an average molecular weight between about 50 and
about 350.
6. The process of claim 5 wherein the average molecular weight is
between about 60 and about 280.
7. The process of claim 6 wherein the average molecular weight is
between about 80 and about 210.
8. The process of claim 2 to which is added a second co-catalyst
compound which comprises one or more compounds of the formula
ZnR'.sub.2 wherein each R', which may be the same or different, is
selected from hydrogen, optionally substituted C.sub.1-C.sub.20
hydrocarbyl, phenyl, F, Cl, Br, I, SR", NR".sub.2, OH, OR", CN, NC
wherein R", which within the same molecule may the same or
different, is C.sub.1-C.sub.20 hydrocarbyl.
9. The process of claim 8 wherein R' is C.sub.1-C.sub.20
hydrocarbyl.
10. The process of claim 9 wherein R' is C.sub.1-C.sub.20
alkyl.
11. The process of claim 10 wherein R' is C.sub.1-C.sub.6
alkyl.
12. The process of claim 11 wherein R' is ethyl.
13. The process of claim 1 wherein one of the aryl moieties of the
2,6-bis(arylimino)pyridine derivative is 2,6-disubstituted with the
group CH.sub.2R or C.sub.2H.sub.5R, wherein R is selected from H
and F, and the other aryl moiety is 2,6-unsubstituted, or wherein
both aryl moieties of the 2,6-bis(arylimino)pyridine derivative are
2,6-disubstituted with F or Cl.
14. The process of claim 1 wherein the 2,6-bis(arylimino)pyridine
derivative has the formula: 3wherein R1 is H or CH.sub.3; R2 is H,
tert-butyl or phenyl and R3 is H, tert-butyl or OR' wherein R'
stands for CH.sub.3, Si(CH.sub.3).sub.3 or eicosyl
(C.sub.2oH.sub.41); or 4
15. The process of claim 1 wherein the coolant medium is selected
from the group consisting of an alkane, an alkene, and an aromatic
compound, and mixtures thereof.
16. The process of claim 1 wherein the coolant medium is selected
from the group consisting of propane, n-pentane, isopentane,
ethylene, 1-butene, o-, m-, and p-xylene, and toluene, and mixtures
thereof.
17. An apparatus for performing the process of making linear
alpha-olefin oligomer of claim 1 comprising a reactor which can
accommodate a liquid phase and a gas phase, an inlet through which
the reactor feed is introduced into the reactor, a reactor bottom
outlet through which the oligomer is removed, a heat exchanger
which is positioned in the gas phase to condense the gas and allow
the condensate to fall therefrom to cool the liquid phase thereby
cooling the liquid, and optionally, a gas outlet and/or an
entrainment separator.
18. The apparatus of claim 17 wherein a gas entrainment separator
which is positioned in the gas phase.
19. An apparatus for performing the process of making linear
alpha-olefin oligomer of claim 1 comprising 1) a reactor which can
accommodate a liquid phase and a gas phase, a reactor feed inlet, a
gas outlet, and a reactor bottom outlet for the reaction products,
2) a heat exchanger which is positioned outside of the reactor,
receives gas from the reactor gas outlet, and cools the gas,
wherein said gas flows from the heat exchanger through a first gas
conduit where part of the gas condenses, 3) a gas-liquid separator
which has a gas outlet and a liquid outlet, receives gas and liquid
from the heat exchanger, and separates gas, which exits the
separator through a second gas conduit and is recycled to the
reactor, from liquid, which exits the separator through a liquid
conduit and is recycled to the reactor.
20. The apparatus of claim 19 further comprising a compressor
between the heat exchanger and the gas-liquid separator.
21. The apparatus of claim 20 further comprising a pump in the
liquid conduit.
22. The apparatus of claim 20 further comprising a compressor
and/or a heat exchanger in the second gas conduit.
23. The apparatus of claim 20 further comprising an entrainment
separator in the reactor in the gas phase.
24. An apparatus for performing the process of making linear
alpha-olefin oligomer of claim 1 comprising 1) a reactor which can
accommodate a liquid phase and a gas phase, a reactor feed inlet, a
gas outlet, and a reactor bottom outlet for the reaction products,
and 2) a heat exchanger which is positioned outside of the reactor,
receives gas from the reactor gas outlet, and cools the gas,
wherein said gas flows from the heat exchanger through a gas
conduit and is recycled to the reactor.
25. The apparatus of claim 15 further comprising a compressor
and/or a heat exchanger in the gas conduit.
Description
FIELD OF THE INVENTION
[0001] The invention pertains to a process for making a linear
alpha-olefin oligomer from ethylene in a reactor having a liquid
and a gas phase, in the presence of a catalyst.
BACKGROUND OF THE INVENTION
[0002] Various processes are known for the production of higher
linear alpha olefins (See, for example, D. Vogt, Oligomerisation of
ethylene to higher a-olefins in Applied Homogeneous Catalysis with
Organometallic Compounds, Ed. B. Cornils, W. A. Herrmann, 2nd
Edition, Vol. 1, Ch. 2.3.1.3, page 240-253, Wiley-VCH 2002). These
commercial processes afford either a Poisson or Schulz-Flory
oligomer product distribution. In such a process, a wide range of
oligomers is typically made.
[0003] In WO 02/00339, WO 02/12151, WO 02/06192, WO 02/28805, WO
01/58874, and WO 99/02472 novel Fe-based ethylene oligomerization
catalysts are described that show high activity and high
selectivity towards linear alpha-olefins. These catalysts, which
are incorporated by reference, are based on iron complexes of a
selected 2,6-pyridinedicarboxaldehyde bisimine or a selected
2,6-diacylpyridine bisimine.
[0004] In the present invention the term "bis-(arylimino)-pyridine"
is used to describe both classes of ligands. Alpha-olefin oligomers
are compounds or a mixture of compounds with the general formula
H.sub.2C.dbd.CH--(CH.sub.2CH.sub.2).sub.nH wherein n is an integer
of 1 or greater. In such oligomers the alpha-olefin oligomer is
usually a mixture of alpha-olefin oligomers with a mean number n
from 1 to 20, preferably from 2 to 10. Alpha-olefin oligomers
prepared according to the process of the present invention
preferably have an average molecular weight between about 50 and
about 350, more preferably between about 60 and about 280, even
more preferably between about 80 and about 210.
[0005] The reaction of ethylene in the presence of the above iron
complex is usually run in the liquid phase in a well-mixed reactor,
typically using an aprotic organic solvent. This reaction generates
a large amount of heat, which should be removed. As described in WO
02/06192 it is preferred to install a plurality of small reactors
in combination with several heat exchangers to help provide
sufficient cooling capacity for the reactor system. The process
temperature, which usually is between about 35.degree. C. and about
90.degree. C., more preferably between about 35.degree. C. and
about 75.degree. C., affects the cost of manufacture of the
alpha-olefins in several ways. The higher the temperature the
smaller the heat exchangers which have to be applied to the
reactor(s), which generally lowers cost. The decay of the active
oligomerization catalyst increases with increasing temperature. It
is found that maximum volumetric production of alpha-olefins
coupled with good absolute productivity of the catalyst usually
occurs in the range of about 45.degree. C. to about 75.degree. C.,
so this temperature range is preferred. Finally, the temperature
also affects the bubble point pressure, the amount of ethylene in
the liquid phase, and the catalyst selectivity. The higher the
temperature the higher the pressure needed to maintain catalyst
selectivity, which increases capital cost of the manufacturing
plant because of, for example, the need for thicker vessels and
larger compressors to attain higher ethylene pressures. Higher
pressure also increases energy costs.
[0006] The amount of ethylene (ethene) oligomerization catalyst
used in the reaction will preferably be the maximum permitted by
the cooling capacity of the reactor(s) and the ethylene mass
transfer from the gas to the liquid phase. Catalyst may be added to
the first reactor only or to one or more subsequent reactors in
series. Differing amounts of catalyst may be added to each reactor.
The oligomerization is quite exothermic, about 100 kJ/mole of
ethylene oligomerized, and as such cooling will usually be applied
to the reactor(s) to maintain the desired process temperature while
maintaining high volumetric productivity of the reactor(s).
[0007] In the prior art cooling is accomplished by running cooling
tubes through the liquid in the interior of one or more of the
reactors to cool the contents. Another method of cooling is to have
one or more heat exchangers external to the reactors and connected
to the reactors by a liquid loop to cool the reactor contents.
These external heat exchangers may be typical shell and tube
exchangers. The reactors may also be jacketed with a cooling
jacket. Some or all of the feeds to some or all of the reactors may
be cooled to allow the sensible heat of the ingredients to cool the
reactors. All these liquid cooling methods, however, suffer from
the disadvantage of wax and polyethylene fouling of the coolers,
which necessitates regular shut down of the reactor to allow
cleaning of the coolers. Furthermore, wax and polyethylene fouling
may increase the paraffinicity of the solvent.
SUMMARY OF THE INVENTION
[0008] It would be advantageous to devise a process without the
above disadvantages. It has now been found that linear alpha-olefin
oligomers can be made in a reactor comprising a liquid and a gas
phase, comprising the steps of catalytically oligomerizing ethylene
in the presence of an iron complex of a 2,6-bis(arylimino)pyridine
derivative, to an alpha-olefin oligomer with an average molecular
weight between about 50 and about 350 under release of heat, and
removing the heat with a heat exchanger, which is not in direct
contact with the liquid phase, using at least part of the gas phase
as a coolant medium.
[0009] This method provides a cooling system having its cooling
elements outside the liquid reaction medium. Since wax and
polyethylene have high boiling points, deposit of wax and
polyethylene can no longer occur, and fouling of the heat exchanger
is effectively prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention is illustrated by the following Figures, which
are not meant to limit the invention in any way, showing a scheme
of an apparatus that can be used for performing the process of the
invention.
[0011] FIG. 1 is a scheme of an apparatus for performing the method
according to the invention with the heat exchanger positioned
outside the reactor.
[0012] FIG. 2 is a scheme of an apparatus for performing the method
according to the invention with the heat exchanger positioned
inside the reactor.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The heat exchanger according to this invention is a
conventional type, such as a shell- and tube-type, and the like.
The heat exchanger is internally cooled with conventional cooling
fluids, like water, ammonia, Freon.RTM. coolant, and the like. The
reaction heat causes the solvents, reactants, and/or reaction
products, which are present in the reaction medium, to evaporate
and subsequently to be cooled by the heat exchanger, after which it
works as a coolant medium for the reactor. The heat exchanger can
be placed inside or outside the reactor. When the heat exchanger is
placed inside the reactor it is preferred that some condensation
occurs on the heat exchanger surface. When the heat exchanger is
placed outside the reactor, it is preferred to apply a forced
circulation of the reactor coolant medium from the gas phase of the
reactor through heat exchanger(s), compressor(s)/pump(s) and
optionally a gas-liquid separator back to the liquid phase of the
reactor. Additionally, this will improve the mixing in the reactor.
After cooling the reactor coolant medium in this loop, some
condensation can occur. This allows application of a separate gas
and liquid return to the reactor using a gas-liquid separator.
Furthermore, it is possible to deliberately remove (part of) this
liquid phase from this gas-liquid separator and route this directly
to the product work-up section. Finally, if full condensation
occurs, return of this liquid to the reactor can be achieved by a
pump instead of a compressor, which lowers costs. This reactor
coolant medium is selected from an alkane, alkene, and aromatic
compound, and mixtures thereof, preferably propane, n-pentane,
isopentane, ethylene, 1-butene, o-, m-, and p-xylene, and toluene,
and mixtures thereof.
[0014] An additional advantage of the present process is the
possibility to apply only one reactor, because the efficiency and
the lack of fouling no longer necessitates the use of a plurality
of small reactors. This adds considerably to the lowering of costs
of the oligomerization process.
[0015] The iron complexes of the 2,6-bis(arylimino)pyridine type
that can be used in the above process are known in the art, and are
described in WO 02/00339, WO 02/12151, WO 02/06192, WO 02/28805, WO
01/58874, and WO 99/02472. Any of these complexes can be used. Best
results, however, are obtained with such iron complexes wherein one
of the aryl moieties of the 2,6-bis(arylimino)pyridine derivative
is 2,6-disubstituted with the group CH.sub.2R or C.sub.2H.sub.5R,
wherein R is selected from H, F, and substituted or unsubstituted
aryl, preferably selected from H and F, and the other aryl moiety
is 2,6-unsubstituted, or wherein both aryl moieties of the
2,6-bis(arylimino)pyridine derivative are 2,6-disubstituted with F
or Cl.
[0016] Particularly useful are the 2,6-bis(arylimino)pyridine
derivatives with the formula: 1
[0017] wherein
[0018] R1 is H or CH.sub.3;
[0019] R2 is H, tert-butyl or phenyl; and
[0020] R3 is H, tert-butyl or OR' wherein R' stands for
CH.sub.3,
[0021] Si(CH.sub.3).sub.3 or eicosyl (C.sub.20H.sub.41); and 2
[0022] The term "aryl" means an aromatic group, such as phenyl,
naphthyl, thienyl, pyridyl, pyrrolyl, and the like. Phenyl is the
preferred aryl group. Preferred phenyl groups are substituted with
CH.sub.3, tert-butyl, F, or OR' wherein R' stands for CH.sub.3 or
Si(CH.sub.3).sub.3.
[0023] In a preferred embodiment an aluminum-based co-catalyst,
preferably a methylaluminoxane, is added to the liquid phase. Where
a co-catalyst such as an alkylaluminum compound is required or
preferred for the active catalyst species, an iron complex of a
2,6-bis(arylimino)pyridine derivative, such as a complex of the
2,6-bis(arylimino)pyridine derivative with FeCl.sub.2, may be
reacted with an alkylaluminum compound, preferably an aluminoxane,
to form an active ethylene oligomerization species. Specific
alkylaluminum compounds include methylaluminoxane (which is an
oligomer with the general formula (MeAlO).sub.n),
(C.sub.2H.sub.5).sub.2AlC.sub.1, C.sub.2H.sub.5AlCl.sub.2- ,
(C.sub.2H.sub.5).sub.3Al and ((CH.sub.3).sub.2CHCH.sub.2).sub.3Al.
A particularly preferred aluminoxane is methyl aluminoxane. The
ratio of aluminum (as alkylaluminum compound) to iron (as a
complex) in the oligomerization may be about 10 to about
10,000.
[0024] Another preferred component of the catalyst systems herein
is a second co-catalyst compound selected from formula ZnR'.sub.2
wherein each R', which may be the same or different, is selected
from hydrogen, optionally substituted C.sub.1-C.sub.20 hydrocarbyl,
phenyl, F, Cl, Br, I, SR", NR".sub.2, OH, OR", CN, NC wherein R",
which within the same molecule may be the same or different, is
C.sub.1-C.sub.20 hydrocarbyl.
[0025] In preferred catalyst systems herein, the second co-catalyst
compound is ZnR'.sub.2 wherein R' is C.sub.1-C.sub.20 hydrocarbyl,
more preferably C.sub.1-C.sub.20 alkyl, even more preferably
C.sub.1-C.sub.6 alkyl. Suitable alkyl groups include methyl, ethyl,
propyl, butyl, and the like. It is especially preferred that the R'
group is a C.sub.1-C.sub.3 alkyl, especially ethyl.
[0026] The second co-catalyst is particularly valuable in
combination with the aluminium-based co-catalyst for increasing the
selectivity of linear alpha olefins in ethylene oligomerization
reactions, and decreasing the amount of unwanted by-products such
as branched olefins, internal olefins, 2,2-disubstituted olefins,
and dienes.
[0027] It has been noted that particularly high selectivity of
linear alpha olefins is achieved when the molar ratio of the metal
of the aluminium-based co-catalyst to the metal of the second
co-catalyst is in the range of from about 5:1 to about 1:5,
preferably from about 3:1 to about 1:3, more preferably from about
2:1 to about 1:2 and especially about 1:1.
[0028] It is possible to add further optional components to the
catalyst systems herein, for example, Lewis acids and bases such as
those disclosed in WO02/28805.
[0029] The active catalyst system may be formed by mixing together
the iron complex of a 2,6-bis(arylimino)pyridine derivative or a
mixture of the iron acetylacetonate complex and the appropriate
2,6-bis(arylimino)pyridine derivative (ligand), first co-catalyst
compound, second co-catalyst compound and any optional additional
compounds, preferably in a solvent.
[0030] An important item in the capital cost of this manufacturing
plant and in its cost of operation is the amount of reactor coolant
medium that must be recycled in the process. Recycling of a gaseous
reactor coolant medium often involves recompression to feed one or
more of the reactors. Compressors and associated equipment add
greatly to capital and operational costs. In the present method the
coolant medium is preferably selected to completely dissolve
ethylene. In this case the coolant medium only requires a single
reactor and a condenser, whereas a simple recycle pump is
sufficient. Thus expensive recycling, such as the use of an
expensive recycle blower, is no longer required, which adds further
to the advantages of the present method.
[0031] FIG. 1 shows a reactor 2 with a liquid phase 3 and a gas
phase 4 being in equilibrium through gas/liquid interface 12. The
liquid phase comprises ethylene, the nickel, palladium, cobalt,
titanium, zirconium, hafnium, vanadium, chromium, molybdenum, or
tungsten complex of a 2,6-bis(arylimino)pyridine derivative,
alpha-olefin oligomer, and optionally solvents and auxiliaries such
as a co-catalyst. The optional solvents are selected as to dissolve
ethylene. The reactor 2 contains an inlet 10 through which the
reactor feed 1 (usually ethylene) is introduced into the reactor 2,
a gas outlet 11, and a reactor bottom outlet 9. In the embodiment
of FIG. 1, outlet is connected through a conduit 14 to heat
exchanger 5a, which is connected through conduit 15 to gas-liquid
separator 6. If necessary, conduit 15 may contain a compressor 7a.
Gas-liquid separator 6 has an outlet for transporting the liquid,
optionally through a pump 8, to obtain a pressurized liquid stream
17 that is recycled via conduit 19 to reactor 2. The gas leaves the
gas-liquid separator 6 through conduit 16, which may optionally
comprise compressor 7b and/or heat exchanger 5b, to obtain a cooled
gas stream 18 that is recycled to reactor 2. If no condensation
occurs in conduit 15, gas-liquid separator 6, and pump 8 are
redundant and may be deleted. In that case conduit 15 can directly
be connected to compressor 7b and/or heat exchanger 5b, if present,
or to conduit 19. Reactor 2 may contain an optional entrainment
separator 13.
[0032] FIG. 2 shows another embodiment of the invention. In this
embodiment the reactor feed 1 is introduced into the reactor 2
through inlet 10. The liquid phase 3 in the reactor is in
equilibrium with the gas phase 4 through gas/liquid interface 12.
In the section of the reactor containing the gas phase 4, a heat
exchanger 20 is placed, which is not in contact with the liquid
phase 3. The section of the gas phase 4 may optionally contain an
entrainment separator 13. The heat exchanger 20 cools the gas,
after which at least part of the gas condenses and the cooled
condensate falls down from the surface of the heat exchanger 20
into the liquid phase 3, thereby cooling the liquid medium. The
reaction product may then be discharged from the reactor through
the reactor bottom outlet 9.
[0033] Hence, according to a further aspect of the present
invention there is provided an apparatus for performing the process
of making linear alpha-olefin oligomer described above, comprising
a reactor, which can accommodate a liquid and a gas phase, an inlet
through which the reactor feed can be introduced into the reactor,
a reactor bottom outlet to remove the oligomer, and a heat
exchanger, which is positioned in the gas phase to condense the gas
and allow the condensate to fall therefrom to cool the liquid
phase, and optionally, an entrainment separator, and/or a
gas-liquid separator.
* * * * *