U.S. patent application number 11/398300 was filed with the patent office on 2006-08-17 for process for the isomerization of an olefin.
Invention is credited to Michael Joseph Doll, Brendan Dermot Murray.
Application Number | 20060183954 11/398300 |
Document ID | / |
Family ID | 23157420 |
Filed Date | 2006-08-17 |
United States Patent
Application |
20060183954 |
Kind Code |
A1 |
Doll; Michael Joseph ; et
al. |
August 17, 2006 |
Process for the isomerization of an olefin
Abstract
A process for the double bond isomerization of an olefin, which
process comprises contacting a feed comprising the olefin with an
isomerization catalyst, wherein prior to contacting the feed with
the isomerization catalyst one or more components of the feed are
pretreated by contacting with a pretreating material which
comprises a zeolite which has a pore size of at least 0.35 nm; a
plant which is suitable for carrying out the isomerization process;
and a process for treating an olefin mixture which comprises a
linear .alpha.-olefin and a vinylidene olefin which is isomeric to
the linear .alpha.-olefin and which is of the general formula
CH.sub.2.dbd.C(R.sup.1)R.sup.2, wherein R.sup.1 represents an ethyl
group and R.sup.2 represents a linear 1-alkyl group, which process
comprises isomerising the vinylidene olefin to form a double bond
isomer of the vinylidene olefin by contacting a feed comprising the
olefin mixture with an isomerization catalyst, and separating the
linear .alpha.-olefin from the double bond isomer of the vinylidene
olefin, wherein prior to contacting the feed with the isomerization
catalyst one or more components of the feed are pretreated by
contacting with a pretreating material which comprises a zeolite
which has a pore size of at least 0.35 nm.
Inventors: |
Doll; Michael Joseph; (Katy,
TX) ; Murray; Brendan Dermot; (Houston, TX) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
23157420 |
Appl. No.: |
11/398300 |
Filed: |
April 5, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10165909 |
Jun 10, 2002 |
7041865 |
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11398300 |
Apr 5, 2006 |
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60300038 |
Jun 21, 2001 |
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Current U.S.
Class: |
585/664 |
Current CPC
Class: |
C07C 5/2518 20130101;
C07C 2529/08 20130101 |
Class at
Publication: |
585/664 |
International
Class: |
C07C 5/25 20060101
C07C005/25 |
Claims
1-14. (canceled)
15. Process equipment suitable for carrying out a process for the
double bond isomerization of an olefin, which process equipment
comprises a pretreating vessel comprising a pretreating material
which comprises a zeolite having a pore size of at least 0.35 nm,
and an isomerization vessel comprising an isomerization catalyst,
which pretreatment vessel and isomerization vessel are arranged so
as to enable that a feed comprising the olefin is contacted with
the isomerization catalyst and that prior to contacting the feed
with the isomerization catalyst one or more components of the feed
is pretreated by contacting with the pretreating material.
16-18. (canceled)
Description
FIELD OF THE INVENTION
[0001] The invention relates to a process of the double bond
isomerization of an olefin, which process comprises contacting a
feed comprising the olefin with an isomerization catalyst.
[0002] As used herein, the term "double bond isomerization" relates
to a shift of a double bond in the molecular structure of an olefin
from a thermodynamically less favorable position to a
thermodynamically more favorable position. An example of a double
isomerization is a shift of the double bond of a linear
.alpha.-olefin from the external, .alpha.-position to an internal
position, for example a .beta.- or .gamma.-position. Another
example is a shift of one or two double bonds of a non-conjugated
diolefin to form a conjugated diolefin. Again another example is a
shift of the double bond of a vinylidene olefin to form a
tri-substituted ethene, e.g. the isomerization of 2-ethyl-1-hexene
to 3-methyl-2-heptene or 3-methyl-3-heptene.
BACKGROUND OF THE INVENTION
[0003] U.S. Pat. No. 5,789,646 discloses a process for the double
bond isomerization of an olefin, which process comprises contacting
a feed comprising the olefin with an isomerization catalyst which
is a solid acid catalyst. The solid acid catalysts which feature in
the working examples of U.S. Pat. No. 5,789,646 are an H-ZSM-5
having a silicon/aluminum atomic ratio of 25 and a crosslinked
sulfonic acid ion exchange resin. U.S. Pat. No. 5,789,646 teaches
that the feed comprising the olefin should preferably be dry.
[0004] U.S. Pat. No. 4,697,040 discloses a process for the double
bond isomerization of an olefin, which process comprises contacting
a feed comprising the olefin with an isomerization catalyst which
comprises a zeolite in the sodium form. The zeolite catalyst of
U.S. Pat. No. 4,697,040 is a specific Y type zeolite, designated
LZ-Y52 (trademark). In the prior art discussion of U.S. Pat. No.
4,697,040, referring to U.S. Pat. No. 3,686,250, it is taught that
highly acid isomerization catalysts have the disadvantage that they
are deactivated at an undesirably high rate by traces of impurities
so that isomerization catalysts of moderate acidity are generally
preferred from a long term activity cost of view and from a low
cost viewpoint. U.S. Pat. No. 3,686,250 suggests employing a guard
bed technique of a catalyst charge of a previous run placed in the
flow path ahead of the principle catalyst bed.
[0005] U.S. Pat. No. 4,749,819 discloses a process for the double
bond isomerization of an olefin, which process comprises contacting
a feed comprising the olefin with an isomerization catalyst which
comprises a zeolite of a suitable channel size, preferably a
ferrierite. U.S. Pat. No. 4,749,819 teaches that the feed may be
pretreated by contacting with a refractory inorganic oxide, for
example alumina, silica, zirconia, magnesia, silica--alumina,
silica--alumina--chromium, etc., or another, unspecified type of
molecular sieve.
[0006] U.S. Pat. No. 5,237,120 discloses a process for the double
bond isomerization of an olefin, which process comprises contacting
a feed comprising the olefin with an isomerization catalyst which
comprises a zeolite of which the outer surface has at least
partially been deactivated for acid catalysed reactions. In the
working examples of U.S. Pat. No. 5,237,120 the feed is pretreated
by contacting it with a pretreating material consisting of
.gamma.-alumina, reduced copper chromite and molecular sieve
zeolite-3A. Zeolite-3A has a pore size of 0.3 nm.
[0007] Although much attention has been given to the pretreating of
the feed to an olefin double bond isomerization process, it is
still desirable to improve the pretreatment thereby improving the
performance of the isomerization catalyst.
SUMMARY OF THE INVENTION
[0008] The present invention provides an improved pretreating
material for use in conjunction with a process for the double bond
isomerization of an olefin. The use of the pretreatment material of
this invention leads to an improved catalyst performance. The
improved catalyst performance may be seen in one or more aspects,
such as an improved catalyst activity, an improved selectivity, an
improved catalyst stability with respect to activity and an
improved catalyst stability with respect to selectivity. In this
context the selectivity may be seen in various ways, for example in
the formation of the double bond isomer of the olefin in question
relative to the formation of other compounds from the olefin, for
example dimers, trimers, skeletal isomers, etc., or in the
formation of one or more isomers from the olefin in question
relative to the conversion of other compounds present in the
reaction mixture.
[0009] The pretreating materials provided by the present invention
comprise a zeolite which has a large pore size, for example of at
least 0.35 nm.
[0010] Accordingly, the present invention provides a process for
the double bond isomerization of an olefin, which process comprises
contacting a feed comprising the olefin with an isomerization
catalyst, wherein prior to contacting the feed with the
isomerization catalyst one or more components of the feed are
pretreated by contacting with a pretreating material which
comprises a zeolite which has a pore size of at least 0.35 nm.
[0011] The present invention also provides process equipment
suitable for carrying out a process for the double bond
isomerization of an olefin, which process equipment comprises a
pretreating vessel comprising a pretreating material which
comprises a zeolite having a pore size of at least 0.35 nm, and an
isomerization vessel comprising an isomerization catalyst, which
pretreatment vessel and isomerization vessel are arranged so as to
enable that a feed comprising the olefin is contacted with the
isomerization catalyst and that prior to contacting the feed with
the isomerization catalyst one or more components of the feed is
pretreated by contacting with the pretreating material.
[0012] The pretreatment according to this invention may very
usefully be applied in conjunction with the isomerization of a
specific type of vinylidene olefin in admixture with a linear
.alpha.-olefin which is isomeric to the vinylidene olefin. In the
isomerization the linear .alpha.-olefin is not or virtually not
converted. The specific vinylidene olefin in question is of the
general formula CH.sub.2.dbd.C(R.sup.1)R.sup.2, wherein R.sup.1
represents an ethyl group and R.sup.2 represents a linear 1-alkyl
group. Such combination of olefins may be present in the reaction
product of an ethene oligomerization process, wherein the linear
.alpha.-olefin is the main product and the vinylidene olefin is a
byproduct. The boiling points of the linear .alpha.-olefin and the
vinylidene olefin are generally so close that their separation by
distillation represents a problem. The isomerization of the
vinylidene olefin then leads to a vinylidene olefin isomer which
can more readily be separated from the linear .alpha.-olefin than
the vinylidene olefin itself (cf. U.S. Pat. No. 5,789,646 and U.S.
Pat. No. 4,697,040, of which the teachings are incorporated herein
by reference).
[0013] Accordingly, the present invention also provides a process
for treating an olefin mixture which comprises a linear
.alpha.-olefin and a vinylidene olefin which is isomeric to the
linear .alpha.-olefin and which is of the general formula
CH.sub.2.dbd.C(R.sup.1)R.sup.2, wherein R.sup.1 represents an ethyl
group and R.sup.2 represents a linear 1-alkyl group, which process
comprises isomerising the vinylidene olefin to form a double bond
isomer of the vinylidene olefin by contacting a feed comprising the
olefin mixture with an isomerization catalyst, and separating the
linear .alpha.-olefin from the double bond isomer of the vinylidene
olefin, wherein prior to contacting the feed with the isomerization
catalyst one or more components of the feed are pretreated by
contacting with a pretreating material which comprises a zeolite
which has a pore size of at least 0.35 nm.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The process of this invention is suitable for effecting the
isomerization of a wide range of olefins. Suitable olefins are for
example linear .alpha.-olefins and non-conjugated diolefins. Most
suitable olefins for the isomerization are vinylidene olefins of
the general formula CH.sub.2.dbd.C(R.sup.1)R.sup.2, wherein R.sup.1
and R.sup.2 represent alkyl groups independently having at least 2
carbon atoms, such that the molecular structure comprises at least
one allylic hydrogen atom. Typically, R.sup.1 and R.sup.2 represent
alkyl groups independently having at most 20 carbon atoms, more
typically at most 16 carbon atoms. Typically, R.sup.1 represents an
ethyl group. Typically, R.sup.2 represents a linear 1-alkyl group,
which preferably comprises an even number of carbon atoms.
Preferred vinylidene olefins are for example 2-ethyl-1-pentene and
2-ethyl-1-heptene, in particular 2-ethyl-1-butene,
2-ethyl-1-hexene, 2-ethyl-1-octene, 2-ethyl-1-decene and
2-ethyl-1-dodecene.
[0015] The olefin to be isomerised may be a plurality of olefins,
for example a plurality of vinylidene olefins as defined
hereinbefore, in particular a plurality of vinylidene olefins which
each carry in their molecular structure alkyl groups R.sup.1
representing ethyl groups and which differ from each other in the
alkyl groups R.sup.2. Preferably, the alkyl groups R.sup.2 are
linear 1-alkyl groups having carbon numbers which differ from each
other by two (for example 5, 7 and 9) and preferably these carbon
numbers are even numbers (for example 4 and 6; or 4, 6, 8 and 10;
or 12, 14 and 16).
[0016] A second olefin may be present in the isomerization, which
is relatively stable and does not isomerise or react otherwise
under the prevailing conditions, or only to a low extent. Examples
of the second olefin are ethene, propene, cyclohexene and
2-methylpropene.
[0017] In a particular embodiment of the present invention the
vinylidene olefin as defined hereinbefore is isomerised in the
presence of a linear .alpha.-olefin, as the second olefin, whereby
the linear .alpha.-olefin is not or virtually not isomerised or
otherwise reacted. Preferably, the linear .alpha.-olefin has the
same carbon number as the vinylidene olefin, so that the linear
.alpha.-olefin represents an isomer of the vinylidene olefin. In
particular, the vinylidene olefin carries in its molecular
structure an alkyl group R.sup.1 representing an ethyl group and
the alkyl group R.sup.2 is a linear 1-alkyl group. For example,
2-ethyl-1-butene may be isomerised in the presence of 1-hexene,
2-ethyl-1-hexene may be isomerised in the presence of 1-octene and
2-ethyl-1-octene may be isomerised in the presence of 1-decene. Two
or more such vinylidene olefins may be isomerised in the presence
of the corresponding, isomeric linear .alpha.-olefins.
[0018] The isomerization catalyst is preferably a solid catalyst,
in particular a solid acid. An eligible solid catalyst is a cation
exchange resin in its acid form, for example crosslinked sulfonic
acid catalyst. More typically, the isomerization catalyst is a
molecular sieve. Eligible molecular sieves are
silica-aluminophosphate molecular sieves or metal
silica-aluminophosphate molecular sieves, in which the metal may
be, for example, iron, cobalt or nickel.
[0019] The pore size of the molecular sieve of the isomerization
catalyst may be selected within wide ranges. Preferably, the pore
size of the molecular sieve of the isomerization catalyst is at
least 0.6 nm, more preferably at least 0.65 nm, most preferably at
least 0.7 nm. Typically the pore size of the molecular sieve of the
isomerization catalyst is at most 1 nm, more typically at most 0.9
nm, preferably at most 0.8 nm. When the pores or channels of the
molecular sieve are not circular, the pore size is herein deemed to
relate to the smaller width of the pores or channels. The pore size
of many of such molecular sieves has been specified in W M Meier
and D H Olson, "Atlas of Zeolite Structure Types", 2.sup.nd Revised
edition (1987), published by the Structure Commission of the
International Zeolite Association. The terms "pore" and "channel"
as used herein in relation to molecular sieves are
exchangeable.
[0020] Preferably, the molecular sieve of the isomerization
catalyst is an aluminosilicate, i.e. a zeolite, typically having a
silicon/aluminum (Si/Al) atomic ratio of at least 1.3, more
preferably at least 1.5, in particular at least 2. Preferably, the
Si/Al atomic ratio is at most 20, more preferably at most 8, in
particular at most 5. As used herein, unless mentioned otherwise,
the Si/Al atomic ratio is the skeletal Si/Al atomic ratio of the
zeolite. The skeletal Si/Al atomic ratio is deemed to be determined
by .sup.29Si--NMR.
[0021] Typically, the molecular sieve of the isomerization catalyst
comprises sodalite cages in its molecular structure. Preferably,
the sodalite cages are arranged in a faujasite structure. Mordenite
zeolites, ZSM-5 zeolites, beta-zeolites or omega-zeolites may be
used as isomerization catalyst as well.
[0022] The molecular sieve of the isomerization catalyst is
preferably in an acidic form, for example in the ammonium form or
in the hydrogen form. This means that the cationic sites of the
molecular sieve of the isomerization catalyst are at least partly
occupied by acidic species, for example ammonium and/or hydrogen
ions. Preferably, the cationic sites of the molecular sieve of the
isomerization catalyst are at least partly occupied by hydrogen
ions, i.e. the molecular sieve is in the hydrogen form. Other
cationic cites may be occupied by, for example alkali metal ions or
alkaline earth metal ions, such as sodium ions or calcium or
magnesium ions. Suitably at least 10%, more suitably at least 50%,
in particular at least 75% of the cationic sites is occupied by
hydrogen and/or ammonium ions, whilst in practice frequently at
most 99.9%, more frequently at most 99% of the cationic sites is
occupied by hydrogen and/or ammonium ions. Preferably at least 10%,
more preferably at least 50%, in particular at least 75% of the
cationic sites is occupied by hydrogen ions, whilst in practice
frequently at most 99.9%, more frequently at most 99% of the
cationic sites is occupied by hydrogen ions.
[0023] If the molecular sieve for use in the isomerization catalyst
is in the ammonium form, it may be converted into the hydrogen form
prior to its use by any suitable means, for example by heating at a
temperature of at least 300.degree. C., for example at a
temperature in the range of from 400 to 600.degree. C.
[0024] Typically the molecular sieve of the isomerization catalyst
has a surface area in the range of from 400 to 1000 m.sup.2/g, more
typically from 600 to 950 m.sup.2/g. As used herein, the surface
area is deemed to have been measured by the method of
ASTM-D3662-92.
[0025] As an example, a molecular sieve which may be used in the
isomerization catalyst is a ZMS-5 zeolite in the hydrogen form
which has a Si/Al. atomic ratio of for example 25 or 80. An example
of a preferred molecular sieve for use in the isomerization
catalyst is CBV 500 (trademark), which is a zeolite having a
faujasite structure, a bulk Si/Al atomic ratio of about 2.6 (the
skeletal Si/Al atomic ratio is believed to be in the range of
2.3-3), a pore size of 0.74 nm and a surface area of about 750
m.sup.2/g. CBV 500 zeolite is available in the ammonium form,
marketed by Zeolyst International. Another example of a preferred
molecular sieve for use in the isomerization catalyst is CBV 400
(trademark), which is a zeolite having a faujasite structure, a
bulk Si/Al atomic ratio of about 2.55 (the skeletal Si/Al atomic
ratio is believed to be in the range of 2.3-3), a pore size of 0.74
nm and a surface area of about 730 m.sup.2/g. CBV 400 zeolite is
available in the hydrogen/sodium form (containing 2.2% w of sodium,
calculated as Na.sub.2O, which is believed to pertain to 80-85% of
the cationic sites being occupied by hydrogen ions). CBV 400
zeolite is marketed by Zeolyst International.
[0026] It is preferred that the molecular sieve for use in the
isomerization catalyst is in the form of particles, for example
pellets, cylinders or beads, which comprise for example at least
10% w, typically at least 50% w, preferably at least 90% w of the
molecular sieve, based on the weight of the particles. In practice
such particles comprise frequently at most 99.99% w, more
frequently at most 99.9% w, most frequently at most 99% w of the
molecular sieve, based on the weight of the particles. A
conventional binder may be present in the particles. Useful
conventional binders may be inorganic materials, such as clay,
silica and/or metal oxides. The molecular sieve for use in the
isomerization catalyst may be compounded with other materials, such
as porous matrix materials, for example, alumina, silica/alumina,
silica/magnesia, silica/zirconia and silica/titania,
silica/alumina/thoria and silica/alumina/zirconia.
[0027] In the present isomerization process a liquid diluent may or
may not be present. Suitable are organic liquid diluents, for
example hydrocarbons, such as alkanes, cycloalkanes and aromatics,
or chlorohydrocarbons.
[0028] The present isomerization process may be conducted by
contacting the feed as a liquid phase with the isomerization
catalyst. The feed comprises as components the olefin to be
isomerised ("the first olefin" hereinafter, for example the
vinylidene olefin as defined hereinbefore) and optionally the
second olefin (for example the linear .alpha.-olefin) and
optionally the liquid diluent. Suitably, the first olefin
represents from 0.01% w to 100% w of the feed. More suitably the
first olefin represents from 0.05% w to 90% w of the feed. The
second olefin, if present, represents suitably from 10% w to 99.99%
w of the feed, more suitably from 20% w to 99.95% w of the feed.
The weight ratio of the first olefin to the second olefin, if
present, is preferably in the range of from 0.05:100 to 10:100, in
particular from 0.1:100 to 5:100. The liquid diluent, if present,
represents suitably from 1% w to 99.99% w of the mixture of
components, more suitably from 10% w to 99.95% w of the feed.
Substances being present in smaller quantities are normally not
considered to be diluents.
[0029] The present isomerization process may be carried out with
the isomerization catalyst dissolved or, as a solid, suspended in
the feed, which is especially suitable when the isomerization
process is carried out as a batch liquid phase process. The
quantity of isomerization catalyst dissolved or suspended may be in
the range of from 0.1 to 20 g/kg feed, preferably from 0.5 to 10
g/kg feed.
[0030] As an alternative, the isomerization process may be carried
out with the solid isomerization catalyst present as a fixed bed,
which is especially suitable when the isomerization process is
carried out as a continuous process, whether as a liquid phase
process or as a gas phase process. A continuous liquid phase
process employing a fixed bed is preferred. The LHSV may be in the
range of from 0.01 to 200 kg/(l.h), preferably from 0.1 to 100
kg/(l.h). In this context, the term "LHSV" stands for the liquid
hourly space velocity which is the mass flow rate divided by the
volume of the catalyst bed. The direction of flow through the
catalyst bed is not material. For example, the direction of flow
may be up-flow or down-flow.
[0031] The present isomerization process may be carried out within
wide ranges of pressures and temperatures which can effect the
desired isomerization. The pressure is suitably in the range of
from 0.01 to 10 MPa, more suitably in the range of from 0.02 to 2
MPa, in particular from 0.05 to 1 MPa. Suitably the temperature is
in the range of from 0 to 300.degree. C., more suitably in the
range of from 10 to 250.degree. C., most suitably in the range of
from 20 to 200.degree. C. When the first olefin is a vinylidene
olefin as defined hereinbefore, the temperature is suitably in the
range of from 0 to 150.degree. C., more suitably in the range of
from 10 to 100.degree. C., most suitably in the range of from 20 to
80.degree. C.
[0032] The isomerization process may be carried out such that the
conversion of the vinylidene olefin over the isomerization catalyst
is at least 5%. It is preferred that the conversion of the
vinylidene olefin is at least 40%, more preferably at least 60%,
most preferably at least 80%. Frequently the conversion of the
vinylidene olefin is complete, however, more frequently the
conversion of the vinylidene olefin at most 99.9%, most frequently
at most 99.8%. When an .alpha.-olefin is present, in particular a
linear .alpha.-olefin, the conversion of the .alpha.-olefin over
the isomerization catalyst is preferably at most 20%, more
preferably at most 10%, most preferably at most 5%. Frequently, the
.alpha.-olefin is not converted at all, more frequently the
conversion of the .alpha.-olefin is at least 0.1%, more frequently
at least 0.2%.
[0033] One or more of the first olefin, the second olefin, if
present, and the liquid diluent, if present, are pretreated before
being contacted with the isomerization catalyst. Without wishing to
be bound by theory, it is believed that the pretreatment leads to
the removal of impurities which could be detrimental to the
performance of the isomerization catalyst, in particular the
catalyst's activity and activity stability. Conceivably, such
impurities may be water or organic compounds comprising
heteroatoms, such as oxygen, nitrogen, sulfur and phosphorus. Such
impurities may have been introduced during the synthesis, work-up,
purification or other processing of the individual components.
[0034] Typically, upon contacting with the isomerization catalyst,
the feed comprises water at a level of at most 50 ppmw, preferably
at most 10 ppmw, in particular at most 1 ppmw, relative to the
weight of the feed. Typically, the content of organic compounds
comprising oxygen heteroatoms is such that the content of the
oxygen heteroatoms is at most 50 ppmw, preferably at most 20 ppmw,
relative to the weight of the feed. Typically, the content of
organic compounds comprising nitrogen heteroatoms is such that the
content of the nitrogen heteroatoms is at most 50 ppmw, preferably
at most 20 ppmw, relative to the weight of the feed. Typically, the
content of organic compounds comprising sulfur heteroatoms is such
that the content of the sulfur heteroatoms is at most 50 ppmw,
preferably at most 20 ppmw, relative to the weight of the feed.
Typically, the content of organic compounds comprising phosphorus
heteroatoms is such that the content of the phosphorus heteroatoms
is at most 10 ppmw, preferably at most 2 ppmw, relative to the
weight of the feed.
[0035] In accordance with this invention the pretreatment comprises
contacting with a pretreating material which comprises a zeolite
which has a pore size of at least 0.35 nm. Combinations with other
pretreating methods may be applied. Suitable other pretreating
methods are distillation, extraction and contacting with another
pretreating material, such as active carbon, alumina, silica and
other zeolites. The pretreatment may be applied to one or more
separate, individual components of the feed. However, it is
preferred to pretreat them together as a mixture, in particular as
the feed to the isomerization process, prior to contacting with the
isomerization catalyst.
[0036] A preferred zeolite for use as the pretreating material is a
zeolite having a pore size of at least 0.5 nm, and most in
particular at least 0.6 nm, and typically it has a pore size of at
most 1.5 nm, more typically at most 1.2 nm, in particular at most 1
nm. The pore size of many of such zeolites has been specified in W
M Meier and D H Olson, "Atlas of Zeolite Structure Types", 2.sup.nd
Revised edition (1987), published by the Structure Commission of
the International Zeolite Association.
[0037] Preferably, the zeolite for use as the pretreating material
comprises sodalite cages in its structure, in particular sodalite
cages which are arranged such as to form a faujasite structure.
Preferably, the zeolite for use as the pretreating material has a
Si/Al atomic ratio of above 1, in particular at least 1.2.
Preferably, the Si/Al atomic ratio of at most 1.5. Preferably, the
zeolite for use as the pretreating material is a zeolite-X.
[0038] The zeolite for use as the pretreating material typically
comprises ions of an alkali metal and/or ions of an alkaline earth
metal occupying at least a part of the cationic sites. Alkali metal
ions are preferred, in particular sodium ions. Examples of suitable
alkaline earth metal ions are calcium ions and magnesium ions.
Suitably at least 10%, more suitably at least 50%, in particular at
least 90% of the cationic sites is occupied by ions of an alkali
metal and/or ions of an alkaline earth metal, whilst in practice
frequently at most 99.9%, more frequently at most 99% of the
cationic sites is occupied by ions of an alkali metal and/or ions
of an alkaline earth metal. Preferably at least 10%, more
preferably at least 50%, in particular at least 90% of the cationic
sites is occupied by alkali metal ions, whilst in practice
frequently at most 99.9%, more frequently at most 99% of the
cationic sites is occupied by alkali metal ions.
[0039] Typically the zeolite for use as the pretreating material
has a surface area in the range of from 400 to 1000 m.sup.2/g, more
typically from 600 to 950 m.sup.2/g.
[0040] Examples of preferred zeolites for use as the pretreating
material are zeolite-10X, in particular zeolite-13X. These zeolites
are readily commercially available, for example from UOP.
Zeolite-10X is an X type zeolite in the calcium form which has a
pore size of about 0.75 nm, a Si/Al atomic ratio in the range of
from 1.2 to 1.5 and a surface area of about 700 m.sup.2/g.
Zeolite-13X is an X type zeolite in the sodium form which has a
pore size of about 8 nm, a Si/Al atomic ratio in the range of from
1.2 to 1.5 and a surface area of about 700 m.sup.2/g.
[0041] It is preferred that the zeolite for use as the pretreating
material is in the form of particles, for example pellets,
cylinders or beads, which comprise for example at least 10% w,
typically at least 50% w, preferably at least 90% w of the zeolite,
based on the weight of the particles. In practice such particles
comprise frequently at most 99.99% w, more frequently at most 99.9%
w, most frequently at most 99% w of the zeolite, based on the
weight of the particles. A conventional binder may be present in
the particles. Useful conventional binders may be inorganic
materials, such as clay, silica and/or metal oxides. The zeolite
for use as the pretreating material may be compounded with other
materials, such as porous matrix materials, for example, alumina,
silica/alumina, silica/magnesia, silica/zirconia and
silica/titania, silica/alumina/thoria and
silica/alumina/zirconia.
[0042] The pretreatment may be carried out by suspending the
pretreating material in the component in question or the mixture of
components, which is especially suitable when the pretreatment is
carried out as a batch liquid phase process. The quantity of the
pretreating material suspended may be in the range of from 0.1 to
50 g/kg component or mixture of components, preferably from 0.2 to
10 g/kg component or mixture of components.
[0043] As an alternative, the pretreatment may be carried out with
the pretreating material present as a fixed bed, which is
especially suitable when the pretreatment process is carried out as
a continuous process, whether as a liquid phase process or as a gas
phase process. A continuous liquid phase process employing a fixed
bed is preferred. The LHSV may be in the range of from 0.05 to 50
kg/(l.h), preferably from 0.1 to 20 kg/(l.h). In this context, the
term "LHSV" stands for liquid hourly space velocity which is the
mass flow rate divided by the volume of the pretreating bed. The
direction of flow through the pretreating bed is not material. For
example, the direction of flow may be up-flow or down-flow.
[0044] The pretreatment using the pretreating material may be
carried out within wide ranges of temperatures and pressures.
Suitably the temperature is in the range of from -20 to 100.degree.
C., more suitably in the range of from -10 to 80.degree. C. The
pressure is suitably in the range of from 0.01 to 10 MPa, more
suitably in the range of from 0.02 to 2 MPa, in particular in the
range of from 0.05 to 1 MPa.
[0045] As set out hereinbefore, in certain embodiments the
isomerization process of this invention is applied to one or more
vinylidene olefins in admixture with the respective isomeric linear
.alpha.-olefin(s). In the molecular structure of the vinylidene
olefins in question the alkyl groups R.sup.1 are ethyl groups and
the alkyl groups R.sup.2 are linear 1-alkyl groups having an even
carbon number, or having consecutive even carbon numbers. Such
mixtures may be obtained from ethene oligomerization processes,
wherein the one or more linear .alpha.-olefins is the main product
and the one or more vinylidene olefins are byproducts. Such ethene
oligomerization processes are known in the art, for example, from
U.S. Pat. No. 4,749,819, U.S. Pat. No. 5,557,027, U.S. Pat. No.
4,528,416, U.S. Pat. No. 4,472,525, US-A-4472522, U.S. Pat. No.
4,284,837, U.S. Pat. No. 4,260,844 and U.S. Pat. No. 4,020,121, of
which the teachings are incorporated herein by reference.
[0046] The ethene oligomerization process may be carried out in the
presence of Ziegler type catalyst such as lithium, sodium,
potassium, beryllium and magnesium metal catalysts. Suitably, the
ethene oligomerization process is carried out in the presence of a
nickel catalyst, wherein the nickel is complexed with a bidentate
chelating ligand. Preferred bidentate chelating ligands have a
tertiary organophosphorus moiety with a suitable functional group
substituted on a carbon atom attached directly to or separated by
no more than two carbon atoms from the phosphorus atom of the
organophosphorus moiety. Examples of preferred bidentate chelating
ligands are o-dihydrocarbylphosphinobenzoic acids, e.g.
o-diphenyl-phosphinobenzoic acid and o-dicyclohexylphosphinobenzoic
acid, and 2-dihydrocarbylphosphinopropionic acids, e.g.
2-diphenylphosphinopropionic acid and
2-dicyclohexyl-phosphinopropionic acid, and the corresponding
alkali metal salts.
[0047] The ethene oligomerization process may or may not be carried
out in the presence of a liquid diluent. Suitable liquid diluents
for use in conjunction with the complexed nickel catalysts comprise
protic or aprotic polar diluents, such as mono- and polyhydric
alcohols, in particular aliphatic diols, such as glycol,
1,3-propanediol and 1,4-butanediol; 1,2-alkylene carbonates, such
as 1,2-ethylene carbonate, 1,2-propylene carbonate and 2,3-butylene
carbonate; and ethers, in particular cyclic ethers such as
tetrahydrofuran.
[0048] The ethene oligomerization process may be carried out in
wide temperature and pressure ranges. Preferred temperatures are in
the range of from 0 to 200 , in particular from 30 to 140.degree.
C. Preferred pressures are in the range of from 0.1 to 35 MPa, in
particular from 2.5 to 15 MPa.
[0049] The oligomerization products may be isolated from the
oligomerization reaction mixture by one or more of phase
separation, extraction with protic or aprotic polar diluent,
extraction with water, and distillation.
[0050] The product of the present isomerization process may be
worked-up and purified by any suitable method. When a vinylidene
olefin is isomerised in the presence of a linear .alpha.-olefin, as
described hereinbefore, the double bond isomer of the vinylidene
olefin may be separated form the linear .alpha.-olefin by
distillation. The process for treating a linear .alpha.-olefin
mixture may constitute a purification process for the linear
.alpha.-olefin as it may yield the linear .alpha.-olefin in a more
pure form.
[0051] Unless specified otherwise, the organic compounds mentioned
herein, for example the organic diluents and the ligands, have
typically at most 40 carbon atoms, more typically at most 20 carbon
atoms, in particular at most 10 carbon atoms, more in particular at
most 6 carbon atoms. As defined herein, ranges for numbers of
carbon atoms (i.e. carbon number) include the numbers specified for
the limits of the ranges.
[0052] The invention will now be illustrated by the following
examples.
EXAMPLE 1 (for comparison)
[0053] A CBV 500 zeolite (trademark) in the form of 1.6 mm ( 1/16
inch) diameter cylinders, obtained from Zeolyst International, was
tested for its ability to catalyse the isomerization of
2-ethyl-1-butene, as follows.
[0054] A sample of 1-hexene was prepared by oligomerizing ethene
using a nickel catalyst, and working-up by procedures involving
extraction with aqueous extraction liquids. Distillation gave the
1-hexene sample as the C.sub.6-cut, which contained as impurities
0.55% w of 2-ethyl-1-butene and about 20 ppmw of water.
[0055] A sample of the zeolite cylinders was heated at 500.degree.
C. in air for a period of 15 hours. A 0.15-g sample was placed in a
bottle with 100 ml of the 1-hexene sample. The bottle was shaken
during 50 minutes at 20.degree. C. and 0.1 MPa pressure, after
which the content of 2-ethyl-1-butene in the 1-hexene was measured.
The result is given in Table I.
EXAMPLES 2-4 (for comparison)
[0056] Example 1 was essentially repeated, except that, instead of
the CBV 500 zeolite, samples of the following zeolites were used:
[0057] LZ-Y52 zeolite (trademark), a commercially available Y type
zeolite in the sodium form which has a pore size of 0.74 nm and a
Si/Al atomic ratio of 2.37 (Example 2), [0058] zeolite-13X (Example
3), and [0059] zeolite-4A (Example 4). All zeolite samples were
obtained and tested in the form of 1.6 mm ( 1/16 inch) diameter
cylinders.
[0060] The results are given in Table I.
EXAMPLES 5-7
[0061] Examples 1 and 2 were essentially repeated, except that
prior to placing the CBV 500 zeolite sample or the LZ-Y52 zeolite
sample in the bottle with 100 ml 1-hexene, the 1-hexene was
pretreated with zeolite-13X (Examples 5 and 7) or zeolite-4A
(Example 6), as pretreatment materials, by employing a procedure as
outlined in Example 3 or Example 4, and separating the 1-hexane
sample from the pretreatment materials. The result is given in
Table I. TABLE-US-00001 TABLE I Isomerisa- 2-ethyl-1- Example
Pretreatment(s) tion butene (% w) 1 **) Distillation *) CBV 500
0.49 zeolite 2 **) Distillation LZ-Y52 0.55 zeolite 3 **)
Distillation zeolite- 0.55 13X 4 **) Distillation zeolite-4A 0.55 5
Distillation, contacting CBV 500 0.24 with zeolite-13X zeolite 6
Distillation, contacting CBV 500 0.36 with zeolite-4A zeolite 7
Distillation, contacting LZ-Y52 0.53 with zeolite-13X zeolite *) of
1-hexene sample preparation; **) for comparison, not according to
the invention
EXAMPLE 8
[0062] A sample of zeolite-13X in the form of 1.6 mm ( 1/16 inch)
diameter cylinders was heated in air at 200.degree. C. A first
stainless steel cylindrical vessel (about 2.5 cm diameter, about 25
cm height) was filled with this zeolite to form a bed of particles.
A sample of CBV 500 zeolite in the form of 1.6 mm ( 1/16 inch)
diameter cylinders was heated in air at 200.degree. C. A second
stainless steel cylindrical vessel (about 2.5 cm diameter, about 5
cm height) was filled with the latter zeolite to form a bed of
particles.
[0063] A flow of a 1-hexene sample similar as employed in Examples
1-7 but containing 0.85% w 2-ethyl-1-butene and having a water
content of about 20 ppmw, was maintained through the first vessel,
and from the first vessel through the second vessel. In both
vessels the flow was up-wards at a rate of 250 ml/hour. In the
first vessel the temperature was at 2.degree. C. and the pressure
was 0.5 MPa. In the second vessel the temperature was 40.degree. C.
and the pressure was 0.5 MPa. After 36 kg of the 1-hexene sample
had passed the vessels the contents of 2-ethyl-1-butene in the
1-hexene flow leaving the second vessel was 0.05% w.
EXAMPLE 9
[0064] Example 8 was essentially repeated, except that instead of
CBV 500 zeolite, a sample of CBV 400 zeolite in the form of 1.6 mm
( 1/16 inch) diameter cylinders was used. After 36 kg of the
1-hexene sample had passed the vessels the contents of
2-ethyl-1-butene in the 1-hexene flow leaving the second vessel was
0.11% w.
EXAMPLE 10
[0065] Example 9 was essentially repeated, except that another
1-hexene sample was employed which is similar as the 1-hexene
sample employed in Examples 1-7 but containing 0.82% w
2-ethyl-1-butene and having a water content of about 20 ppmw, and
that the flow rate was 240 g/hour. After 24 kg of the 1-hexene
sample had passed the vessels the content of 2-ethyl-1-butene in
the 1-hexene flow leaving the second vessel was 0.50% w.
EXAMPLE 11
[0066] Example 10 was essentially repeated, except that instead of
CBV 400 zeolite, a sample of CBV 8062 zeolite in the form of 1.6 mm
( 1/16 inch) diameter cylinders was used. CBV 8062 zeolite
(trademark), obtained from Zeolyst International, is a ZSM-5 type
zeolite, in the hydrogen form and it has a Si/Al atomic ratio of
80. After 24 kg of the 1-hexene sample had passed the vessels the
content of 2-ethyl-1-butene in the 1-hexene flow leaving the second
vessel was 0.62% w.
[0067] In the examples it is shown that the isomerization catalysts
have an improved performance when using as a pretreating material a
zeolite which has a large pore size, like zeolite-4A and
zeolite-13X (cf. examples 5 and 6 vs. example 1 and example 7 vs.
example 2). More specifically, it is shown that the combined use of
the pretreating zeolite and the isomerization catalyst leads to a
synergistic effect, viz. the combined use has lead to a decrease in
vinylidene olefin content which is more than the sum of what was
achieved by using only the pretreating zeolites (examples 3 and 4)
and what was achieved by using only the isomerization catalysts
(examples 1 and 2). This synergistic effect is unobvious and
surprising as no such combination has been suggested in the prior
art, whilst the pretreating zeolites are known to have
isomerization catalyst properties (cf. U.S. Pat. No. 4,697,040 and
U.S. Pat. No. 3,686,250) and isomerization catalysts may be used as
a pretreating material (cf. U.S. Pat. No. 3,686,250).
[0068] In the examples it is also shown that an improved catalyst
performance is accomplished by selecting an isomerization catalyst
which comprises a molecular sieve in an acidic form having a pore
size of at least 0.6 nm (cf. example 1 vs. example 2, example 5 vs.
example 7, examples 8-10 vs. example 11).
* * * * *