U.S. patent application number 10/958828 was filed with the patent office on 2005-03-03 for nickel-containing ethylene oligomerization catalyst and use thereof.
Invention is credited to Brown, David Stephen, Robertson, Richard Edward.
Application Number | 20050049447 10/958828 |
Document ID | / |
Family ID | 25260587 |
Filed Date | 2005-03-03 |
United States Patent
Application |
20050049447 |
Kind Code |
A1 |
Brown, David Stephen ; et
al. |
March 3, 2005 |
Nickel-containing ethylene oligomerization catalyst and use
thereof
Abstract
A process for the oligomerization of ethylene to a mixture of
olefinic products having high linearity is provided, by using a
catalyst comprising a reaction product of a simple divalent nickel
salt; a boron hydride reducing agent; a water soluble base; a
ligand selected from an o-dihydrocarbylphosphinobenzoic acid and
alkali metal salt thereof; and, a phosphite.
Inventors: |
Brown, David Stephen; (Sugar
Land, TX) ; Robertson, Richard Edward; (Baton Rouge,
LA) |
Correspondence
Address: |
Donald F. Haas
Shell Oil Company
Legal - Intellectual Property
P.O. Box 2463
Houston
TX
77252-2463
US
|
Family ID: |
25260587 |
Appl. No.: |
10/958828 |
Filed: |
October 5, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10958828 |
Oct 5, 2004 |
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09832070 |
Apr 10, 2001 |
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6825148 |
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Current U.S.
Class: |
585/502 |
Current CPC
Class: |
B01J 31/24 20130101;
B01J 2231/20 20130101; B01J 23/755 20130101; C07C 2531/02 20130101;
B01J 31/185 20130101; C07C 2523/755 20130101; C07C 2/36 20130101;
C07C 2531/24 20130101; B01J 2531/847 20130101; B01J 31/2404
20130101 |
Class at
Publication: |
585/502 |
International
Class: |
C07C 002/02 |
Claims
1-22. (canceled).
22. A process for the preparation of a mixture of olefinic products
having high linearity comprising: A) contacting ethylene in a polar
organic solvent under conditions effective to produce linear,
alpha-olefins in the presence of a catalyst produced by reacting
components comprising: a) a simple divalent nickel salt having a
solubility of at least 0.001 mole per liter in said polar organic
solvent; b) a boron hydride reducing agent; c) a water soluble
base; d) a ligand selected from the group consisting of
o-dihydrocarbylphosphinobenzoic acids and alkali metal salts
thereof; and, e) a trivalent phosphite, wherein the molar ratio of
the ligand to the trivalent phosphite ranges from about 50:1 to
about 1000:1; thereby producing a mixture of olefinic products
having high linearity; and B) recovering the olefinic products
having high linearity.
23. The process of claim 22 in which the process is carried out at
a temperature of between about 0.degree. and about 200.degree.
C.
24. The process of claim 22 in which the nickel salt comprises a
nickel halide.
25. The process of claim 22 in which the nickel salt comprises a
nickel alkanoate.
26. The process of claim 22 in which the boron hydride reducing
agent is an alkali metal borohydride.
27. The process of claim 22 in which the water soluble base is
selected from the group consisting of potassium bicarbonate,
potassium methoxide, potassium ethoxide, potassium isopropoxide,
potassium hydroxide, potassium tert-butoxide, sodium bicarbonate,
sodium methoxide, sodium ethoxide, sodium isopropoxide, sodium
hydroxide and sodium tert-butoxide.
28. The process of claim 22 in which the water soluble base is
potassium hydroxide.
29. The process of claim 22 in which the trivalent phosphite is an
alkyl phosphite
30. The process of claim 22 in which the trivalent phosphite is
triethyl phosphite.
31. The process of claim 22 in which the ligand is selected from
the group consisting of diarylphosphinobenzoic acids,
arylcycloalkylphosphinobenzoi- c acids and the alkali metal salts
thereof.
32. The process of claim 23 in which the nickel salt comprises a
nickel halide, the boron hydride reducing agent is an alkali metal
borohydride, the water soluble base is a potassium hydroxide, the
trivalent phosphite is triethyl phosphite and the ligand is
o-dihydrocarbylphosphinobenzoic acid.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a certain nickel-containing
catalyst and a process for the oligomerization of ethylene to a
mixture of olefinic products having high. linearity using such
catalyst.
BACKGROUND OF THE INVENTION
[0002] The production of a mixture of olefinic products which are
substantially alpha-olefins and which have a high degree of
linearity are known. Such olefins comprise for example, those of
the C.sub.4-C.sub.10 range, useful as comonomers for LLDPE or as
synthetic lubricants; those of the C.sub.12-C.sub.20 range, useful
as detergents; and higher olefins. The lower molecular weight
olefins can be converted to sulfonates or alcohols by known
commercial processes. The C.sub.12-C.sub.20 olefins find use in the
detergent-products area. Lower molecular weight alcohols can be
esterified with polyhydric acids, e.g., phthalic acid to form
plasticizers for polyvinylchloride.
[0003] U.S. Pat. No. 3,676,523, herein incorporated by reference,
discloses the use of an ethylene oligomerization catalyst in the
production of such olefinic products which comprises (1) a divalent
nickel salt, (2) a boron hydride reducing agent, and (3) an
o-dihydrocarbylphosphinobenzoic acid or alkali metal salt
thereof.
[0004] One drawback to the use of this catalyst, however, is
expense. There exists a need for a lower cost catalyst in the
production of such olefinic products.
SUMMARY OF THE INVENTION
[0005] This invention relates to a process for the oligomerization
of ethylene to a mixture of olefinic products having high linearity
by using a catalyst comprising a simple divalent nickel salt; a
boron hydride reducing agent; a water soluble base; a ligand
selected from the group consisting of
o-dihydrocarbylphosphinobenzoic acids and alkali metal salts
thereof; and a trivalent (three-coordinate) phosphite.
DETAILED DESCRIPTION OF THE INVENTION
[0006] It has been found that the use of a certain ligand provides
for a cost effective catalyst useful in the production of olefinic
products.
[0007] Nickel Salts: In general, any simple divalent nickel salt
can be employed for preparing the catalyst composition of the
invention provided the nickel salt is sufficiently soluble in the
reaction medium. By the term "simple divalent" nickel salt is meant
a nickel atom having a formal valence of +2 and bonded through
ionic or electrovalent linkages to two singly charged anionic
groups (e.g., halides) or to one doubly charged anionic group.
(e.g., carbonate) and not complexed with or coordinated to any
other additional molecular or ionic species. Simple divalent nickel
salts therefore do not encompass complex divalent nickel salts
which are bonded to one or two anionic groups and additionally
complexed or coordinated to neutral chelating ligands or groups
such as carbon monoxide and phosphines. However, simple divalent
nickel salts are meant to include nickel salts containing water of
crystallization in addition to one or two anionic groups.
[0008] In most instances, a simple divalent nickel salt with a
solubility in the reaction diluent or solvent employed for catalyst
preparation of at least 0.001 mole per liter (0.001M) is
satisfactory for use as the nickel catalyst precursor. A solubility
in the reaction diluent or solvent of at least 0.01 mole per liter
(0.01M) is preferred, and a solubility of at least 0.05 mole per
liter (0.05M) is most preferred. Reaction diluents and solvents
suitably employed for catalyst preparation are the polar organic
solvents suitably employed for the oligomerization process which
solvents are defined below.
[0009] Suitable simple divalent nickel salts include inorganic as
well as organic divalent nickel salts. Illustrative inorganic
nickel salts are nickel halides such as nickel chloride, nickel
bromide and nickel iodide, nickel carbonate, nickel chlorate,
nickel ferrocyanide, and nickel nitrate. Illustrative organic
divalent nickel salts are nickel salts of carboxylic acids such as
nickel alkanoates of up to ten carbon atoms, preferably of up to
six carbon atoms, e.g. nickel formate, nickel acetate, nickel
propionate, nickel hexanoate and the like; nickel oxalate; nickel
benzoate and nickel naphthenate. Other suitable organic salts
include nickel benzenesulfonate, nickel citrate, nickel
dimethylglyoxime and nickel acetylacetonate.
[0010] Nickel halides, especially nickel chloride, and nickel
alkanoates, in part because of their availability at low cost and
solubility in polar organic solvents are preferred nickel
salts.
[0011] Dihydrocarbylphosphinobenzoic Acid: The
o-dihydrocarbylphosphino-be- nzoate ligands employed in the
preparation of the catalyst composition of the invention generally
have from eight to 30 carbon atoms, but preferably from 14 to 20
carbon atoms, and are preferably represented by the formula (I):
1
[0012] wherein R is a monovalent hydrocarbyl group and M is
hydrogen or an alkali metal. The M group is preferably hydrogen,
sodium or potassium. Illustrative examples of R groups are
hydrocarbon alkyl groups such as methyl, ethyl, isobutyl, lauryl,
stearyl, cyclohexyl, and cyclopentyl; hydrocarbon alkenyl R groups
having aromatic substituents such as benzyl, phenylcyclohexyl, and
phenylbutenyl. Aromatic R groups such as phenyl, tolyl, xylyl and
p-ethylphenyl. Preferred R groups are aromatic groups of six to ten
carbon atoms, especially phenyl, and cycloalkyl of five to ten
carbon atoms, especially cyclohexyl.
[0013] Illustrative examples of o-dihydrocarbylphosphinobenzoate
ligands of formula (I) are o-diphenylphosphinobenzoic acid,
o-(methylphenylphosphino)benzoic acid,
o-(ethyltolylphosphino)benzoic acid, o-dicyclohexylphosphinobenzoic
acid, o-(cyclohexylphenylphosphino)b- enzoic acid,
o-dipentylphosphinobenzoic acid and the alkali metal salts
thereof.
[0014] Preferred benzoate ligands of formula (I) are those wherein
the R groups are aromatic or cycloalkyl of six to ten carbon atoms,
particularly diarylphosphinobenzoic acids,
arylcycloalkylphosphinobenzoic acids and the alkali metal salts
thereof. Such aryl- and cycloalkyl-substituted phosphino-benzoate
ligands are preferred largely because catalyst compositions
prepared therefrom catalyze the oligomerization of ethylene to a
product mixture containing a high proportion of oligomers in the
useful C.sub.12-C.sub.20 carbon range.
[0015] Although the o-dihydrocarbylphosphinobenzoate ligands are
suitably employed as the free acid, better results are occasionally
obtained with the alkali metal salts of the o-dihydrocarbylbenzoic
acid. The alkali metal salts are suitably preformed from the
benzoic acid by treatment with an alkali metal hydroxide or oxide
solution prior to catalyst preparation or, alternatively, the
carboxylic acid salt is generated in situ by the reaction of
equimolar amounts of the carboxylic acid and an alkali metal
hydroxide during catalyst preparation.
[0016] When preparing the catalyst, the molar ratio of nickel salt
to benzoate ligand (free acid or salt thereof) is at least 1:1,
i.e., at least one mole nickel salt is provided for each mole of
benzoate ligand. Suitable molar ratios of nickel salt to benzoic
acid ligand (or salt thereof) range from about 1:1 to about 10:1,
although molar ratios of about 1:1 to about 3:1 are preferred.
[0017] Boron Hydride Reducing Agent: In general, any boron hydride
salt reducing agent of reasonable purity is suitable for use in the
process of the invention. Specific examples include alkali metal
borohydrides such as sodium borohydrides, potassium borohydride and
lithium borohydride; alkali metal alkoxyborohydrides wherein each
alkoxy has one to four carbon atoms, such as sodium
trimethoxyborohydride and potassium tripropoxyborohydride and
tetraalkylammonium borohydrides wherein each alkyl has one to four
carbon atoms, such as tetraethylammonium borohydride. Largely
because of commercial availability, alkali metal borohydrides are
preferred and especially preferred is sodium borohydride.
[0018] When preparing the catalyst, the molar ratio of boron
hydride salt to nickel salt is at least about 0.2:1. There does not
appear to be a definite upper limit on the boron hydride/nickel
ratio, but for economic reasons it is especially preferred that the
molar ratio be not greater than about 15:1. The preferred molar
ratio of boron hydride to nickel salt is usually between about
0.25:1 and about 5:1; more preferred is a ratio between about 0.5:1
and about 2:1. Best results are often obtained when the molar ratio
is about 2:1.
[0019] Water soluble base: Any water soluble base may be used for
pH adjustment purposes. Examples include potassium bicarbonate,
potassium methoxide, potassium ethoxide, potassium isopropoxide,
potassium hydroxide, and potassium tert-butoxide as well as the
corresponding sodium compounds.
[0020] When preparing the catalyst, the molar ratio of water
soluble base to boron hydride salt ranges from about 0:1 to about
5:1. The preferred molar ratio of water soluble base to boron
hydride is usually between about 0.25:1 and about 2:1.
[0021] Phosphite: Any trivalent phosphite can be used, however,
alkyl phosphites are preferred and linear alkyl phosphites are most
preferred. Examples of suitable phosphites are triisopropyl-,
triisobutyl-, tri-sec-butyl-, trimethyl-, triethyl-, tri-n-propyl-,
and tri-n-butylphosphite. When preparing the catalyst, the molar
ratio of benzoate ligand to phosphite can range from about 50:1 to
about 1000:1, preferably in the range of from about 100:1 to about
300:1.
[0022] Catalyst Preparation: The catalyst composition of the
present invention is suitably preformed by contacting the catalyst
precursors, i.e., the nickel salt, the benzoic acid ligand, the
phosphite, the water soluble base and the boron hydride reducing
agent, in the presence of ethylene in a polar organic solvent (or
diluent), e.g., polar organic diluents or solvents employed for the
oligomerization process which are not reduced by the boron hydride
reducing agent. In a preferred modification, the nickel salt,
borohydride and base are contacted under an ethylene atmosphere.
The benzoic acid ligand and the trivalent phosphite are then added.
Generally, the catalyst precursors are contacted under about 10 to
about 1,500 psig of ethylene.
[0023] The catalyst is generally prepared at temperatures of about
0.degree. C. to about 50.degree. C., although substantially ambient
temperatures, e.g. about 10.degree. C. to about 30.degree. C., are
preferred. Contact times of about 5 minutes to 1 hour are generally
satisfactory, but can be longer.
[0024] Reaction Conditions: The ethylene is contacted with the
catalyst composition in the liquid phase in the presence of a
reaction solvent or diluent or solvent of up to about 30 liters per
mole of ethylene are satisfactorily employed. Generally, the
concentration of the catalyst, calculated as nickel metal, in the
solvent or diluent is at least 0.001M, but preferably from about
0.002M to about 0.01M.
[0025] Suitable solvents (or diluents) are polar organic compounds
such as organic compounds containing atoms such as oxygen, sulfur,
nitrogen and phosphorus incorporated in functional groups such as,
for example, hydroxy, alkoxy, aryloxy, carbalkoxy, alkanoyloxy,
cyano, amino, alkylamino, diakylamine, amide, N-alkylamide,
N,N-dialkylamide, sulfonylalkyl and like functional groups.
Illustrative oxygenated organic solvents are fully esterified
polyacyl esters of polyhydroxy alkanes such as glycerol triacetate,
tetracyl esters of erythritol, diethylene glycol diacetate;
monoesters such as ethyl acetate, butyl propionate and phenyl
acetate; cycloalkyl ethers, e.g., dioxane, tetrahydropyran; acyclic
alkyl ethers, e.g., dimethoxyethane, diethylene glycol dimethyl
ether and dibutyl ether, aromatic ethers such as anisole,
1,4-dimethoxybenzene and p-methoxytoluene; aliphatic alcohols such
as methanol trifluoroethanol, hexafluoroethanol, trifluoropropanol,
sec-butanol, perfluorobutanol, octanol, dodecanol, cycloalkanols,
e.g., cyclopentanol, and cyclo-hexanol, polyhydric acyclic
hydroxyalkanes such as glycerol and trimethylene glycol,
alkanediols of two to ten carbon atoms such as ethylene glycol,
propylene glycol, 1,4-butanediol and 2,5-hexanediol; phenols, such
as cresol, p-chlorophenol, m-bromophenol, 2,6-dimethylphenol,
p-methoxyphenol, 2,4-dichlorophenol; and alkylene carbonates such
as ethylene carbonate, propylene carbonate and butylene carbonate.
Illustrative examples of nitrogen-containing organic solvents are
nitriles, e.g., acetonitrile and propionitrile; amines, e.g.,
butylamine, dibutylamine, trihexylamine, N-methylpyrolidine,
N-methylpiperidine, and aniline; N,N-dialkylamides, e.g.,
N,N-dimethylformamide and N,N-dimethylacetamide. Illustrative
examples of sulfur-containing solvents are sulfolane and
dimethylsulfoxide and illustrative phosphorus-containing solvents
are trialkylphosphate, e.g., trimethylphosphate, triethylphosphate
and tributylphosphate and hexaalkylphosphoramides such as
hexamethylphosphoramide.
[0026] Preferred reaction diluents and solvents are oxygenated
organic solvents. Especially preferred are alkanediols of four to
six carbon atoms, e.g., 1,4-butanediol and 2,5-hexanediol. Polar
organic solvents and diluents are preferred for use in the process
in part because the ethylene oligomerization product mixture is
essentially insoluble in such solvents and diluents. For example,
when a polar organic solvent such as an alkanediol is employed, a
two phase reaction mixture is formed, i.e., one phase comprising
the ethylene oligomerization product mixture, i.e., the
alpha-olefins, and a second phase comprising the nickel catalyst
and the reaction diluent of solvent. Where a two phase reaction is
formed, the ethylene oligomerization product phase is separated and
the catalyst containing diluent or solvent phase is utilized for
further ethylene oligomerization. Polar organic solvents are also
preferred in part because the same solvents are employed in
catalyst preparation as defined above.
[0027] The precise method of establishing ethylene/catalyst contact
during the oligomerization reaction is not critical. In one
embodiment, the catalyst composition and the solvent are charged to
an autoclave or similar pressure reactor, the ethylene is
introduced, and the reaction mixture is maintained with agitation
at reaction temperature and pressure for the desired reaction
period. In the modification wherein a polar organic solvent is
employed and a two phase reaction is formed, ethylene is passed in
a continuous manner into a reaction zone containing the catalyst
composition and the diluent while ethylene oligomerization product
mixture which is produced is concomitantly withdrawn from the
reaction zone.
[0028] In general, the oligomerization process is conducted at
moderate temperatures and pressures. Suitable reaction temperatures
vary from about 0.degree. C. to about 200.degree. C. The reaction
is conducted at or above atmosphere pressure. The precise pressure
is not critical so long as the reaction mixture is maintained
substantially in a liquid phase. Typical pressures can vary from
about 10 psig to about 5,000 psig with the range from about 400
psig to about 1,500 psig being preferred.
[0029] The oligomerization products are separated and recovered
from the reaction mixture by conventional methods such as
fractional distillation, selective extraction, adsorption and the
like. The reaction solvent, catalyst and any unreacted ethylene can
be recycled for further utilization. Spent catalyst, i.e., catalyst
no longer active for ethylene oligomerization, can be regenerated
for example, by reacting with additional boron hydride reducing
agent and nickel salt in the molar ratios (based on benzoic acid
ligand) hereinbefore defined. Additional benzoic acid ligand can be
added to the regenerated catalyst but it is not required to
regenerate the spent catalyst.
[0030] During the oligomerization process ethylene is converted to
dimer, trimer, tetramer, and larger oligomers. The products are
characterized by a high proportion (greater than about 95%) of
linear terminal olefins with high linearity (greater than about
90%). The particular product composition generally depends upon the
catalyst of the invention employed, the solvent employed, the
reaction conditions, particularly reaction temperatures and diluent
and whether the catalyst is used in the homogeneous or
heterogeneous state. Depending upon the desired product mixture,
the optimized components and conditions can readily be determined
by one skilled in the art.
[0031] The ethylene oligomer products are materials of established
utility and many are chemicals of commerce. The products can be
converted by conventional catalysts to the corresponding
alcohols.
[0032] The instant invention will be illustrated by the following
illustrative embodiments which are provided for illustration only
and are not to be construed as limiting the invention.
[0033] A series of ethylene oligomerization reactions was conducted
with a nickel catalyst prepared by reacting nickel chloride
hexahydrate (NiCl.sub.2.6H.sub.2O), potassium hydroxide, a
dihydrocarbylphosphinobenz- oic acid, sodium borohydride and
optionally triethylphosphite in a reaction medium of 1,4-butanediol
and ethylene. In this set of examples, Example 1 illustrates the
effect of triethylphosphite addition in conjunction with reducing
the o-dihydrocarbylphosphinobenzoic charge. Example 2 illustrates
the effect of reducing the o-dihydrocarbylphosphino- benzoic charge
only. Example 3 represents the normal mode of operation and serves
as the control experiment.
EXAMPLE 1
[0034] This reaction was conducted by charging 0.496 millimoles of
nickel chloride hexahydrate, NiCl.sub.2.6H.sub.2O, 181 ml
1,4-butanediol and 600 psig of ethylene to a 1-liter reactor at
room temperature, with stirring. After approximately 10 minutes of
stirring, 0.657 millimoles of sodium borohydride in aqueous
solution with 0.225 millimoles of potassium hydroxide were slowly
charged to the reactor. A 15 ml portion of 1,4-butanediol was used
to flush this solution into the reactor. After an additional 10
minutes of stirring, 4 g of 1,4-butanediol containing 0.188
millimoles of o-dihydrocarbylphosphinobenzoic acid and 0.00069
millimoles of triethylphosphite were added to the reactor. An
additional 15 ml of 1,4-butanediol was used to flush this solution
into the reactor. The reactor pressure was increased to 800 psig of
ethylene and the internal temperature was raised to 93.degree. C.
Once the temperature stabilized, the ethylene pressure was
increased to 1300 psig, with ethylene fed on demand to maintain the
operating pressure. The reaction was allowed to proceed until 125 g
of ethylene had been consumed. At this point, the reactor was
cooled to 65.degree. C. and the ethylene was vented off. The
resulting oligomer product was isolated and analyzed for
carbon-number distribution (K-factor determination) and alpha
olefin content.
EXAMPLE 2 (COMPARATIVE)
[0035] The procedure given in Example 1 was followed with the
exception that the triethylphosphite was omitted.
EXAMPLE 3 (COMPARATIVE)
[0036] The procedure given in Example 1 was followed with the
exceptions that triethylphosphite was omitted and the
o-dihydrocarbylphosphinobenzoi- c acid charge was increased to
0.225 millimoles.
[0037] The preceding examples were evaluated on the basis of rate,
product distribution (K-factor), and product quality. Table 1
contains the rate and K-factor data. Since Example 3 is the
control, its rate has been normalized to 1 with the other rates
given in relative terms. Table 2 contains the product quality
expressed as weight percent linear alpha olefin for selected carbon
numbers.
1TABLE 1 Rate and K-factor data. Relative Example Rate K-factor 1
1.3 0.728 2 0.65 0.747 3 1.0 0.735
[0038]
2TABLE 2 Weight percent linear alpha olefin content by carbon
number. Carbon Number Example 1 Example 2 Example 3 10 98.2 97.7
97.8 12 97.8 98.2 97.2 14 96.3 98.3 96.6 16 95.6 97.6 95.7 18 96.3
96.9 94.9
* * * * *