U.S. patent application number 17/827216 was filed with the patent office on 2022-09-08 for antifouling oligomerization catalyst systems.
This patent application is currently assigned to Saudi Arabian Oil Company. The applicant listed for this patent is Saudi Arabian Oil Company, Sumitomo Chemical Company, Limited. Invention is credited to Hussain Al Yami, Motaz Khawaji, Sohel Shaikh, Wei Xu.
Application Number | 20220280927 17/827216 |
Document ID | / |
Family ID | 1000006362321 |
Filed Date | 2022-09-08 |
United States Patent
Application |
20220280927 |
Kind Code |
A1 |
Shaikh; Sohel ; et
al. |
September 8, 2022 |
ANTIFOULING OLIGOMERIZATION CATALYST SYSTEMS
Abstract
A catalyst system that may reduce polymeric fouling may include
at least one titanate compound, at least one aluminum compound, and
an antifouling agent. The antifouling agent may be chosen from one
or more of a phosphonium or phosphonium salt; a sulfonate or a
sulfonate salt; a sulfonium or sulfonium salt; an ester including a
cyclic moiety; an anhydride; a polyether; and a long-chained
amine-capped compound. The catalyst system may further include a
non-polymeric ether compound.
Inventors: |
Shaikh; Sohel; (Dhahran,
SA) ; Khawaji; Motaz; (Thuwal Jeddah, SA) ; Al
Yami; Hussain; (Thuwal Jeddah, SA) ; Xu; Wei;
(Dhahran, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Saudi Arabian Oil Company
Sumitomo Chemical Company, Limited |
Dhahran
Chiba |
|
SA
JP |
|
|
Assignee: |
Saudi Arabian Oil Company
Dhahran
SA
Sumitomo Chemical Company, Limited
Chiba
JP
|
Family ID: |
1000006362321 |
Appl. No.: |
17/827216 |
Filed: |
May 27, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15181923 |
Jun 14, 2016 |
|
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17827216 |
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62181955 |
Jun 19, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J 31/0225 20130101;
C07C 2/88 20130101; B01J 31/0268 20130101; C07C 2531/38 20130101;
C07C 2531/04 20130101; B01J 31/0244 20130101; B01J 31/06 20130101;
C07C 2531/14 20130101; C07C 2531/12 20130101; B01J 2231/20
20130101; C07C 2531/025 20130101; C07C 2531/06 20130101; B01J 31/04
20130101 |
International
Class: |
B01J 31/06 20060101
B01J031/06; B01J 31/02 20060101 B01J031/02; B01J 31/04 20060101
B01J031/04; C07C 2/88 20060101 C07C002/88 |
Claims
1. A catalyst that reduces polymeric fouling, the catalyst system
comprising: at least one titanate compound; at least one aluminum
compound; and an antifouling agent chosen from one or more of a
sulfonate or a sulfonate salt, or a sulfonium or sulfonium
salt.
2. The catalyst of claim 1, where the antifouling agent comprises a
sulfonate or a sulfonate salt.
3. The catalyst of claim 2, where the antifouling agent comprises
one or more of sodium dodecylbenzenesulfonate, sodium
dioctylsulfonsuccinate, tetrabutylphosphonium methanesulfonate,
tetrabutylphosphonium p-toluenesulfonate,
hexadecyltrimethylammonium p-toluene sulfonate,
3-(dimethyl(octadecyl)ammonio)propane-1-sulfonate,
3,3'-(1,4-didodecylpiperazine-1,4-diium-1,4-diyl)bis(propane-1-sulfonate)-
, and 3-(4-(tert-butyl)pyridinio)-1-propanesulfonate.
4. The catalyst of claim 1, where the antifouling agent comprises a
sulfonium or sulfonium salt.
5. The catalyst of claim 1, further comprising a non-polymeric
ether compound.
6. The catalyst of claim 5, where the non-polymeric ether compound
is tetrahydrofuran, a dioxane, or tetrahydropyran.
7. The catalyst system of claim 1, where at least one of the
titanate compounds is an alkyl titanate.
8. The catalyst system of claim 7, where the alkyl titanate has the
structure Ti(OR).sub.4, where R is a branched or straight chain
alkyl radical comprising from 2 to 8 carbon atoms.
9. The catalyst system of claim 7, where the alkyl titanate is
chosen from tetraethyl titanate, tetraisopropyl titanate,
tetra-n-butyl titanate, or 2-tetraethylhexyl titanate.
10. The catalyst system of claim 1, where at least one of the
aluminum compounds has the structure AlR'.sub.3 or AlR'.sub.2H,
where R' is a branched or straight chain alkyl radical comprising
from 2 to 8 carbon atoms.
11. The catalyst system of claim 1, where at least one of the
aluminum compounds is chosen from triethylaluminum,
tripropylaluminum, tri-iso-butylaluminum, trihexylaluminum, or an
aluminoxane.
12. The catalyst system of claim 1, where a molar ratio of total
titanate compound to total aluminum compound is from 1:10 to
1:1.
13. The catalyst system of claim 1, where a molar ratio of total
titanate compound to total antifouling agent is from 1:10 to
1:0.01.
14. The catalyst system of claim 1, where a molar ratio of total
titanate compound to total non-polymeric ether compound is from
1:10 to 1:0.
15. A method for selectively producing 1-butene, the method
comprising: contacting ethylene with a catalyst to oligomerize the
ethylene to selectively form 1-butene, where the catalyst system
comprises: at least one titanate compound; at least one aluminum
compound; and an antifouling agent chosen from one or more of a
sulfonate or a sulfonate salt, or a sulfonium or sulfonium
salt.
16. The catalyst of claim 15, where the antifouling agent comprises
a sulfonate or a sulfonate salt.
17. The catalyst of claim 16, where the antifouling agent comprises
one or more of sodium dodecylbenzenesulfonate, sodium
dioctylsulfonsuccinate, tetrabutylphosphonium methanesulfonate,
tetrabutylphosphonium p-toluenesulfonate,
hexadecyltrimethylammonium p-toluene sulfonate,
3-(dimethyl(octadecyl)ammonio)propane-1-sulfonate,
3,3'-(1,4-didodecylpiperazine-1,4-diium-1,4-diyl)bis(propane-1-sulfonate)-
, and 3-(4-(tert-butyl)pyridinio)-1-propanesulfonate.
18. The catalyst of claim 16, where the antifouling agent comprises
a sulfonium or sulfonium salt.
19. The catalyst of claim 15, further comprising a non-polymeric
ether compound.
20. The method of claim 15, where at least one of the titanate
compounds is an alkyl titanate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional Application of U.S.
application Ser. No. 15/181,923 filed Jun. 14, 2016, which claims
the benefit of U.S. Provisional Application Ser. No. 62/181,955
filed Jun. 19, 2015, each of which are incorporated by reference in
their entireties herein.
BACKGROUND
Field
[0002] Embodiments of the present disclosure generally relate to
catalyst systems used in ethylene oligomerization, and more
specifically relate to antifouling catalyst systems used in
ethylene oligomerization which may reduce undesired
polymerization.
Technical Background
[0003] 1-Butene and 1-hexene are important petrochemicals,
especially for the production of polyethylene. The reaction of
ethylene and other alpha-olefins, especially 1-butene and 1-hexene,
forms various grades of linear low density polyethylene (LLDPE), a
useful commercial polymer. A source of 1-butene is the butene
fraction from the effluent of a hydrocarbon cracker, such as a
steam cracker or fluidized catalytic cracker. However, the process
for recovering 1-butene from such an effluent requires several
difficult process steps that may make the process undesirable.
[0004] Several commercial processes selectively oligomerize
ethylene into alpha olefins such as 1-butene and 1-hexene. A
commercially successful dimerization process is the Alphabutol.TM.
Process, developed by the Institute Francais du Petrole (IFP),
described in A. Forestiere, et al., "Oligomerization of Monoolefins
by Homogenous Catalysts", Oil & Science and Technology--Review
de l'Institute Francais du Petrole, pages 663-664 (Volume 64,
Number 6, November 2009). This process uses a bubble-point reactor
that contains 1-butene as a process fluid to oligomerize ethylene
selectively into 1-butene.
[0005] There is a known problem with oligomerization systems:
polymer formation. Long residence times and poor heat removal from
the highly exothermic reactions lead to the formation of
polyethylene-based residues. A side effect of chronic fouling is
increasingly frequent process shutdowns and higher maintenance
costs for removing adhered polymer residues. Polymer residues may
build layer upon layer and eventually close off openings and ports
in locations with fluid flow. Additionally, a polymer coating along
the wall of a reactor may act as an insulator, which may negatively
affect heat transfer to the reactor system. Polymer can also
collect debris that can be catalytically active or that can poison
the reaction process.
[0006] An especially troublesome issue is the formation of "hot
spots." A hot spot is an area where external cooling is ineffective
and catalyst activity is high. It represents a loss of process
control. A hot spot can be an area of collected polymer that
includes catalytically active material that fosters side-reactions,
including polymerization. If left unchecked, the hot spot can
eventually lead to a process shutdown due to the loss of cooling
capacity, a runaway polymerization reaction, or both.
SUMMARY
[0007] Accordingly, there is a continual need for effective methods
to prevent polymeric fouling on reactor system walls and tubes
while maintaining the desired oligomerization rate and selectivity
to form reaction product.
[0008] According to one embodiment, a catalyst system that may
reduce polymeric fouling may comprise at least one titanate
compound, at least one aluminum compound, and an antifouling agent.
The antifouling agent may be chosen from one or more of a
phosphonium or phosphonium salt; a sulfonate or a sulfonate salt; a
sulfonium or sulfonium salt; an ester comprising a cyclic moiety;
an anhydride; a polyether; and a long-chained amine-capped
compound. The catalyst system may further comprise a non-polymeric
ether compound.
[0009] According to another embodiment, 1-butene may be selectively
produced by a method that may comprise contacting ethylene with a
catalyst system to oligomerize the ethylene to selectively form
1-butene. The catalyst system may comprise at least one titanate
compound, at least one aluminum compound, and an antifouling agent.
The antifouling agent may be chosen from one or more of a
phosphonium or phosphonium salt; a sulfonate or a sulfonate salt; a
sulfonium or sulfonium salt; an ester comprising a cyclic moiety;
an anhydride; a polyether; and a long-chained amine-capped
compound.
[0010] Additional features and advantages of the embodiments
described in this disclosure will be set forth in the detailed
description which follows, and in part will be readily apparent to
those skilled in the art from that description or recognized by
practicing the embodiments described, including the detailed
description which subsequently follows, and the claims.
DETAILED DESCRIPTION
[0011] One or more embodiments of the present disclosure are
directed to catalyst systems which may be utilized in promoting
ethylene oligomerization, such as the dimerization of ethylene to
form 1-butene or 1-hexene, while reducing reactor fouling caused by
undesired polymerization. These catalyst systems are sometimes
referred to in this disclosure as "antifouling ethylene
oligomerization catalyst systems" or "antifouling catalyst
systems". The antifouling catalyst systems described may comprise
at least one titanate compound, at least one aluminum compound, and
at least one antifouling agent. The antifouling catalyst systems
may further comprise one or more non-polymeric ether compounds, and
the components of the antifouling catalyst system may be mixed in a
solvent such as hexane. The antifouling catalyst systems may be
used to selectively oligomerize ethylene to produce 1-butene, while
reducing undesirable polymerization, sometimes referred to in this
disclosure as "fouling". For example, reactor fouling may occur due
to the formation of solid polyethylene-based residues which may
reduce fluid flow and fully block or at least partially block
fluids in a reactor system from flowing at a desired rate. It
should be understood that the "antifouling ethylene oligomerization
catalyst systems" or "antifouling catalyst systems" described may
not completely eliminate fouling during a reaction. However, these
catalyst systems reduce fouling as compared with catalyst systems
which do not include an antifouling agent as described in the
present disclosure. Also, it should be understood that while the
catalyst systems of the present disclosure may be useful in
ethylene oligomerization reactions, such as ethylene dimerization
to form 1-butene, they may also be useful for the catalysis of
other chemical reactions, and the antifouling catalyst systems
described in this disclosure should not be considered limited in
their use to the dimerization of ethylene to 1-butene. It should
further be understood that the antifouling agents described in this
disclosure may be incorporated with other catalyst systems which
contain, for example, non-titanium based catalysts.
[0012] As described previously in this disclosure, embodiments of
the described antifouling catalyst systems may comprise one or more
titanate compounds which may serve as a catalyst in the catalyst
systems described in this disclosure. While several titanate
compounds may be included in the antifouling catalyst system, in
some embodiments a single titanate compound may be included in the
antifouling catalyst system. In one or more embodiments, the
titanate compound may be an alkyl titanate. An alkyl titanate may
have the structure Ti(OR).sub.4 in which R is a branched or
straight chain alkyl group. In one or more embodiments, each alkyl
group may comprise from 2 to 8 carbons, where each R group may be
the same or different. Suitable alkyl titanates may include
tetraethyl titanate, tetraisopropyl titanate, tetra-n-butyl
titanate (sometimes referred to as titanium butoxide or tetrabutyl
orthotitanate), 2-tetraethylhexyl titanate, or combinations
thereof. In one or more embodiments, the titanate compound of the
antifouling catalyst system consists of tetra-n-butyl titanate.
[0013] As also described previously in this disclosure, embodiments
of the described antifouling catalyst systems may comprise one or
more aluminum compounds which may act as co-catalysts in the
catalyst systems described in this disclosure. While several
aluminum compounds may be included in the antifouling catalyst
system, in some embodiments a single aluminum compound may be
included. In one or more embodiments, one or more aluminum alkyl
compounds may be included in the antifouling catalyst system.
Aluminum alkyl compounds may have a structure of AlR'.sub.3 or
AlR'.sub.2H, where R' is a straight chain or branched alkane
comprising from 1 to 20 carbons, or an aluminoxane structure (that
is, a partial hydrolysate of trialkylaluminum compounds). The R'
groups of the aluminum alkyl compounds may be the same or different
from one another. For example, and not by way of limitation,
suitable aluminum alkyl compounds may include triethylaluminum,
tripropylaluminum, tri-iso-butylaluminum, trihexylaluminum, or
combinations thereof. In one or more embodiments, the aluminum
compound of the antifouling catalyst system consists of
triethylaluminum.
[0014] The antifouling catalyst systems described in this
disclosure include at least one antifouling agent. An antifouling
agent may be any additive to a catalyst system which decreases
fouling by polymer production. Antifouling agents contemplated
include phosphoniums or phosphonium salts, sulfonates or sulfonate
salts, sulfoniums or sulfonium salts, esters, anhydrides,
polyethers, and long-chained amine-capped compounds. It should be
understood that as used in this disclosure, antifouling agents
which are named for a particular chemical moiety (for example, a
"sulfonate antifouling agent" or a "phosphonium antifouling agent")
comprise at least one of that particular chemical moiety but may
include additional chemical moieties. For example, a "sulfonate
antifouling agent" is an antifouling agent which includes a
sulfonate moiety and a "phosphonium antifouling agent" is an
antifouling agent which includes a phosphonium moiety.
[0015] In one or more embodiments, the antifouling catalyst system
comprises one or more phosphonium antifouling agents. As used in
this disclosure, phosphonium antifouling agents include any
compound comprising the phosphonium structure depicted in Chemical
Structure #1, where R.sub.1, R.sub.2, R.sub.3, and R.sub.4
represents chemical groups which may contain other moieties, and
the various R groups may be identical or different from one
another. Generally, phosphonium antifouling agents may be
introduced into the antifouling catalyst system as phosphonium
salts, where the phosphonium cation forms an ionic bond with an
anion compound. As used in this disclosure, phosphonium antifouling
agents include phosphonium salts or dissociated phosphonium
cations.
##STR00001##
Chemical Structure #1--Generalized Phosphonium Cation
[0016] Suitable phosphonium antifouling agents include, without
limitation, tetraalkyl phosphonium salts. For example, the
antifouling agent may include tetraalkyl phosphonium halides (such
as, for example, tetrabutyl phosphonium halide), phosphonium
malonates (such as, for example, tetrabutylphosphonium malonate),
trihexyltetradecylphsophonium halides (such as, for example,
trihexyltetradecylphsophonium bromide), tetrabutylphosphonium
halides (such as, for example, tetrabutylphosphonium iodide),
tetrabutylphosphonium tetrahaloborates (such as, for example,
tetrabutylphosphonium tetratluoroborate), tetrabutylphosphonium
halides (such as, for example, tetrabutylphosphonium chloride),
tetrabutylphosphonium hexahalophosphates (such as, for example,
tetrabutylphosphonium hexafluorophosphate), or
tetrabutylphosphonium tetrahaloborates (such as, for example,
tetrabutylphosphonium tetrafluoroborate). As used throughout this
disclosure, a halide may include fluoride, chloride, bromide, or
iodide (and "halo" may include the elements fluorine, chlorine,
bromine, or iodine). In one or more embodiments, the R groups (that
is, R.sub.1, R.sub.2, R.sub.3, and R.sub.4) may be branched or
unbranched alkanes, alkenes, or aryls, and the R groups may be
identical or different from one another.
[0017] In one or more embodiments, the antifouling catalyst system
comprises one or more sulfonate antifouling agents. As used in this
disclosure, sulfonate antifouling agents include any compound
comprising the structure depicted in Chemical Structure #2, where R
represents a chemical group, which may contain other moieties.
Generally, sulfonate antifouling agents may be introduced into the
antifouling catalyst system as a sulfonate salt, where the
sulfonium anion forms an ionic bond with a cation compound. As used
in this disclosure, sulfonium antifouling agents include sulfonium
salts or dissociated sulfonium anions.
##STR00002##
Chemical Structure #2--Generalized Sulfonate Anion
[0018] Suitable sulfonate antifouling agents include, without
limitation, sulfonate salts. For example, sulfonate antifouling
agents may include, without limitation, sodium
dodecylbenzenesulfonate, sodium dioctylsulfonsuccinate,
tetrabutylphosphonium methanesulfonate, tetrabutylphosphonium
p-toluenesulfonate, and hexadecyltrimethylammonium p-toluene
sulfonate. In other embodiments, suitable antifouling agents may
include non-salt sulfonates (that is, sulfonates which do not
dissociate as salts), such as ammonium sulfonates. For example,
non-salt sulfonates suitable as antifouling agents include, without
limitation, 3-(dimethyl(octadecyl)ammonio)propane-1-sulfonate,
3,3-(1,4-didodecylpiperazine-1,4-diium-1,4-diyl)bis(propane-1-sulfonate),
and 3-(4-(tert-butyl)pyridinio)-1-propanesulfonate.
[0019] In one or more embodiments, the antifouling catalyst system
comprises one or more sulfonium antifouling agents. Sulfonium
antifouling agents are generally depicted in Chemical Structure #3,
where R.sub.1, R.sub.2, and R.sub.3 represent chemical groups which
may contain other moieties, and the various R groups (that is,
R.sub.1, R.sub.2, and R.sub.3) may be identical or different from
one another. Generally, sulfonium antifouling agents may be
introduced into the antifouling catalyst system as sulfonium salts,
where the sulfonium cation forms an ionic bond with an anion
compound. As used in this disclosure, sulfonium antifouling agents
include sulfonium salts or dissociated sulfonium cations.
##STR00003##
Chemical Structure #3--Generalized Sulfonium Cation
[0020] In another embodiment, the antifouling agent may include an
ester antifouling agent or an anhydride antifouling agent where, in
some embodiments, the ester or anhydride antifouling agent
comprises a cyclic moiety. Suitable ester or anhydride antifouling
agents which contain a cyclic moiety may include, without
limitation, .epsilon.-caprolactone, 2-phenylethyl acetate, and
polyisobutenyl succinic anhydride. In some embodiments, the ester
or anhydride moiety is included in the cyclic moiety. However, in
other embodiments, the ester or anhydride moiety is separate from
the cyclic moiety. Example cyclic moieties include, without
limitation, cyclic alkyls, and aryls, but may include any chemical
moiety which includes a ringed structure of atoms. In some
embodiments, the ester or anhydride antifouling agent may be an
ester or anhydride-capped polymer that has a number average
molecular weight (Mn) of from 150 grams per mole (g/mol) to 200,000
g/mol (for example, from 150 g/mol to 1,000 g/mol, from 150 g/mol
to 2,000 g/mol, from 150 g/mol to 3,000 g/mol, from 150 g/mol to
5,000 g/mol, from 150 g/mol to 10,000 g/mol, from 150 g/mol to
50,000 g/mol, from 150 g/mol to 100,000 g/mol, from 150 g/mol to
150,000 g/mol, from 1,000 g/mol to 200,000 g/mol, from 5,000 g/mol
to 200,000 g/mol, from 10,000 g/mol to 200,000 g/mol, from 50,000
g/mol to 200,000 g/mol, or from 100,000 g/mol to 200,000
g/mol).
[0021] In another embodiment, the antifouling agent may include one
or more polyether antifouling agents. The polyether antifouling
agents may include monomer units comprising carbon chains with one,
two, three, four, or even more carbons separating ether moieties.
For example, one polyether contemplated in this disclosure includes
that depicted in Chemical Structure #4, where m is equal to from 1
to 10 (for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, or even more,
such as m equal to at least 10, at least 25, at least 50, or at
least 75, and less than or equal to 100), and n is from 1 to
50,000. R in Chemical Structure 4 may represent a hydrogen atom, or
an alkyl with or without branches or substitutions. In embodiments,
R may include at least 5, at least 10, or even more carbon atoms).
For example, a suitable polyether antifouling agent may be
polytetrahydrofuran (where m=4). According to one or more
embodiments, the polyether antifouling agent may have a number
average molecular weight. (Mn) of from 150 grams per mole (g/mol)
to 200,000 g/mol (for example, from 150 g/mol to 1,000 g/mol, from
150 g/mol to 2,000 g/mol, from 150 g/mol to 3,000 g/mol, from 150
g/mol to 5,000 g/mol, from 150 g/mol to 10,000 g/mol, from 150
g/mol to 50,000 g/mol, from 150 g/mol to 100,000 g/mol, from 150
g/mol to 150,000 g/mol, from 1,000 g/mol to 200,000 g/mol, from
5,000 g/mol to 200,000 g/mol from 10,000 g/mol to 200,000 g/mol,
from 50,000 g/mol to 200,000 g/mol, or from 100,000 g/mol to
200,000 g/mol).
##STR00004##
Chemical Structure #4--Example Polyether Antifouling Agent
[0022] In another embodiment, the antifouling agent may include one
or more long-chained amine-capped antifouling agents. In one or
more embodiments, the long-chained amine-capped antifouling agent
may have a number average molecular weight (Mn) of from 150 grams
per mole (g/mol) to 200,000 g/mol (for example, from 150 g/mol to
1,000 g/mol, from 150 g/mol to 2,000 g/mol, from 150 g/mol to 3,000
g/mol, from 150 g/mol to 5,000 g/mol, from 150 g/mol to 10,000
g/mol, from 150 g/mol to 50,000 g/mol, from 150 g/mol to 100,000
g/mol, from 150 g/mol to 150,000 g/mol, from 1,000 g/mol to 200,000
g/mol, from 5,000 g/mol to 200,000 g/mol, from 10,000 g/mol to
200,000 g/mol, from 50,000 g/mol to 200,000 g/mol, or from 100,000
g/mol to 200,000 g/mol). Suitable long-chained amine-capped
antifouling agent include, without limitation,
polyisobutene-mono-succinimide and
polyisobutene-bis-succinimide.
[0023] It should be understood that while some embodiments may
contain an antifouling agent that is a single chemical species, in
other embodiments, two or more different antifouling agent species
may be present as the antifouling agent. In embodiments, two or
more different antifouling agent species of the same type may be
present. For example, the catalyst system may comprise two
different species of phosphonium, two different species of
sulfonate, two different species of sulfonium, two different
species of esters, an anhydride, two different species of
polyethers, or two different species of long-chained amine-capped
compounds. In additional embodiments, the catalyst system may
comprise two or more different types of antifouling agents (that
is, two or more of any of a phosphonium or phosphonium salt, a
sulfonate or a sulfonate salt, a sulfonium or sulfonium salt, an
ester comprising a cyclic moiety, an anhydride, a polyether, and a
long-chained amine-capped compound).
[0024] Some antifouling agent species may include two or more types
of antifouling agents. For example, salts which have an anion of
one type of antifouling agent and a cation of a different
antifouling agent may generally comprise two types of antifouling
agents. Examples of such antifouling agents include
tetrabutylphosphonium methanesulfonate and tetrabutylphosphonium
p-toluenesulfonate, which are salts that include a sulfonate and a
phosphonium.
[0025] In one or more embodiments, the antifouling catalyst system
may comprise one or more non-polymeric ether compounds. The one or
more ether compounds may include cyclic non-polymeric ethers such
as, but not limited to, tetrahydropyran (THF), a dioxane, a
tetrahydropyran (THP), or combinations thereof. As used in this
disclosure, "non-polymeric" ethers refer to compounds which include
one or more ethers but do not include long ether polymer chains.
Usually, these non-polymeric ethers comprise one or two ether
moieties, and comprise less than 10 ether moieties. While the
antifouling catalyst systems described in this disclosure do not
require an ether compound in all embodiments, antifouling catalyst
systems which include esters or anhydrides as antifouling agents
may be particularly suited for not including an ester. It is
believed that the ester or anhydride functionalities of some
antifouling agents may at least partially replicate or mimic the
functionality of ethers in the antifouling catalyst systems,
rendering some embodiments of antifouling catalyst systems which
include esters or anhydrides sufficient for their purpose without
an additional ether compound.
[0026] The antifouling catalyst systems may comprise at least one
or more titanate compounds, one or more aluminum compounds, and one
or more antifouling agents. In one or more embodiments, the molar
ratio of total titanate compound to total aluminum compound may be
from 1:10 to 1:1 (such as, for example, from 1:10 to 1:2, from 1:10
to 1:3, from 1:10 to 1:4, from 1:10 to 1:5, from 1:10 to 1:6, from
1:10 to 1:7, from 1:10 to 1:8, from 1:10 to 1:9, from 1:9 to 1:1,
from 1:8 to 1:1, from 1:7 to 1:1, from 1:6 to 1:1, from 1:5 to 1:1,
from 1:4 to 1:1, from 1:3 to 1:1, or from 1:2 to 1).
[0027] In one or more embodiments, the molar ratio of total
titanate compounds to total antifouling agent may be from 1:10 to
1:0.01 (such as, for example, from 1:10 to 1:0.05, from 1:10 to
1:0.1, from 1:10 to 1:0.3, from 1:10 to 1:0.5, from 1:10 to 1:0.7,
from 1:10 to 1:1, from 1:10 to 1:2, from 1:10 to 1:3, from 1:10 to
1:5, from 1:5 to 1:0.01, from 1:3 to 1:0.01, from 1:2 to 1:0.01,
from 1:1 to 1:0.01, from 1:0.7 to 1:0.01, or from 1:0.3 to
1:0.01).
[0028] In one or more embodiments, the molar ratio of total
titanate compounds to total non-polymeric ether compounds may be
from 1:10 to 1:0 (such as, for example, from 1:5 to 1:0, from 1:3
to 1:0, from 1:2 to 1:0, from 1:1 to 1:0, from 1:0.5 to 1:0, from
1:0.3 to 1:0, from 1:0.1 to 1:0, from 1:10 to 1:0.1, from 1:10 to
1:0.5, from 1:10 to 1:1, from 1:10 to 1:2, or from 1:10 to
1:5).
[0029] It should be understood that the molar ratios of components
of the antifouling catalyst systems described previously in this
disclosure are representative of the total amount of each component
of the antifouling catalyst system relative to the total amount of
titanate compound, where the "total" amount refers to the molar
amount of all species of the antifouling catalyst system which may
be considered as a particular component type (that is, titanate
compound, aluminum compound, non-polymeric ether compound, or
antifouling agent). The total amount of a component may include two
or more chemical species which are titanate compounds, aluminum
compounds, non-polymeric ether compounds, or antifouling agents,
respectively.
[0030] According to another embodiment of the present disclosure,
1-butene may be produced by contacting ethylene with the
antifouling catalyst system described previously to oligomerize the
ethylene to form 1-butene. In one or more embodiments, the ethylene
and antifouling catalyst system are supplied to a reactor and
mixed. The reaction may be performed as a batch reaction or as a
continuous process reaction, such as a continuous stir tank reactor
process. According to further embodiments, the pressure of the
reactor may be from 5 bar to 100 bar, and the reactor temperature
may be from 30 degrees Celsius (.degree. C.) to 180.degree. C.
However, process conditions outside of these ranges are
contemplated, especially in view of the specific design of the
reactor system and concentrations of the reactants and catalysts.
The reactions of the present disclosure primarily limit or do not
include polymerization of ethylene (for example, polymers
comprising 100 or more monomer ethylene units). In embodiments,
polymer formation may be limited to less than 500, less than 300,
or even less than 100 parts per million of reactant.
[0031] In one or more embodiments, without being bound by theory,
it is believed that heteroatoms of the antifouling agents may form
weak coordination with the titanate compound utilized as the
catalyst in the catalyst system. It is believed that, in one or
more embodiments, the alkyl groups or other relatively long-chained
groups of the antifouling agents may serve in some capacity to
prevent ethylene access to the catalytic center of the titanate
compound. The restriction of access of the ethylene to the titanate
catalytic site may reduce the polymerization of ethylene and thus
reduce reactor fouling.
[0032] In one or more embodiments, the introduction of the
antifouling agent into a catalyst system may suppress polymer
formation while not greatly reducing catalytic activity of 1-butene
formation, in one embodiment, polymer formation (fouling) may be
reduced by at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%,
90%, or even 95% by the inclusion of an antifouling agent. In one
embodiment, 1-butene production may be increased, stay the same, or
may decrease by less than or equal to 50%, 40%, 30%, 20%, 10% or
even 5% by the inclusion of an antifouling agent. In some
embodiments, antifouling agents may both reduce the polymer
formation (such as by at least 5%, 10%, 20%, 30%, 40%, 50%, 60%,
70%, 80%, 90% or even 95%) and increase, not effect, or decrease
1-butene production rate by less than or equal to 50%, 40%, 30%,
20%, 10% or even 5%. Reduction in polymer formation rates and
catalytic activity on a percentage basis are based on catalyst
systems which include one or more antifouling agents described as
compared with catalyst systems which are void of an antifouling
agent.
Examples
[0033] The various embodiments of antifouling catalyst systems will
be further clarified by the following examples. The examples are
illustrative in nature, and should not be understood to limit the
subject matter of the present disclosure.
[0034] To evaluate the anti-fouling effects of the antifouling
catalyst systems described, ethylene oligomerization reactions were
carried out and evaluated. Multiple sample antifouling catalyst
systems were formulated which had different antifouling agents or
no additional antifouling agent (as a control sample listed as
"Comparative Example in Table 1). For the experiments, catalyst
mixtures were used that contained titanium tetrabutoxide (denoted
as "Ti" in Table 1), THF, triethyl aluminum (sometimes referred to
as "TEAL"), and antifouling agents (denoted as "AFA" in Table 1).
The molar ratio of Ti:AFA for each example is listed in Table 1.
The molar ratio of Ti:THF:TEAL in the examples was 1:6:7.5. The
oligomerization experiments were conducted in a rig which included
8 autoclave reactors each having a volume of 400 milliliters (mL).
Prior to the experimental runs, the rig was subjected to
inertization process which included evacuating the reactors with an
oil vacuum pump and heating to 160.degree. C. After a stable
temperature had been reached, the rig was pressurized to 4 bar with
nitrogen and the stirrers were operated with a stirring speed of
about 300 rpm. Then, three minutes following the start of the
pressurization, the gas outlet valves were opened to release the
nitrogen to the exhaust. Two minutes after the gas release had
started, the valves from the main exhaust pipe to the vacuum pump
were opened to evacuate the rig. The rig was evacuated for 15
minutes. The gas outlet valves were then closed, and the rig was
pressurized with nitrogen again. The pump-pressurize cycles were
run for at least 30 hours. The rig was then evacuated in vacuum for
a further 6 to 8 hours. During the last one hour, the autoclave
reactors were cooled down to 45.degree. C. The rig was then
pressurized to 3 bar until the reaction was started.
[0035] Chargers were prepared, which included the components of the
catalyst mixtures. To prepare the chargers, two stock solutions
were prepared in a glove box. Heptane was utilized as a solvent,
and an amount of heptane was utilized, such that the autoclave
reactors were nominally filled. The first solution contained the
TEAL co-catalyst mixed with 90% of the heptane. The second solution
contained the titanium tetrabutoxide catalyst, the THF, and the
antifouling agents mixed with 10% of the heptane. The first
solution and the second solution were put into first solution
chargers and second solution chargers, respectively.
[0036] To run the oligomerization experiment, the pressure in the
rig was released to about 0.2 bar. The chargers with the second
solution of TEAL/heptane were injected into the reactors. The
charging was achieved by pressurizing the chargers with ethylene to
10 bar and opening the valve between the charger and the reactor.
The contents of the second solution charger were then injected,
using ethene as the charging gas with a pressure of 35 bar. The
target pressure for the reactors was set to 23 bar. The gas dosage
into the reactor was started automatically. The temperature in the
reactor rose and the temperature was set to the target value of
53.5.degree. C. After the start of the ethene dosage, the reaction
was run for 75 min.
[0037] After 75 minutes of reaction time, the reaction was
terminated by the injection of 1 mL of ethanol. The pressure was
released from the reactors, and the temperature was set to
20.degree. C. The reactors were opened and the contents of the
reactor, including the baffles and stirrers, were removed and
placed in a heating oven at 75.degree. C. for one hour. The residue
in the reactor was then washed with a 10 wt. % aqueous sulfuric
acid solution to dissolve any catalyst residues. The remaining
solid polymer was filtered and dried overnight in an oven at
110.degree. C. and weighed.
[0038] Table 1 shows the dimerization activity and weight of
polymer deposit for reactions which utilized each of the sample
catalyst systems. As is evident by the reaction data of Table 1,
the addition of the antifouling additives reduced polymer formation
to some degree while maintaining relatively high dimerization
activity.
TABLE-US-00001 TABLE 1 Activity (grams of ethylene per Polymer
Produced Experiment Molar Ratio hour per millimoles in parts per
Number of Ti:AFA of titanium million (and in mg) AFA chemical
species Comparative .sup. 1:0 228 1,310 (149) N/A Example Example
#1 0.3:1 237 55 (6.5) tetrabutylphosphonium bromide Example #2
0.3:1 9 0 (0) tetrabutylphosphonium malonate Example #3 0.3:1 216
97 (8) sodium dodecylbenzenesulfonate Example #4 .sup. 3:1 208 96
(10) sodium dodecylbenzenesulfonate Example #5 0.3:1 166 187 (36)
sodium dioctylsulfonsuccinate Example #6 0.3:1 242 99 (12)
3-(dimethyl(octadecyl)ammonio)propane-1-sulfonate Example #7 0.3:1
234 145 (17) 3,3'-(1,4-didodecylpiperazine-1,4-diium-1,4-
diyl)bis(propane-1-sulfonate) Example #8 0.3:1 229 289 (33)
3-(4-(tert-butyl)pyridinio)-1-propanesulfonate Example #9 0.3:1 226
354 (40) 1,4-didodecylpiperazine Example #10 0.3:1 230 228 (32)
2-phenylethyl acetate Example #11 0.3:1 185 141 (13) polyisobutenyl
succinic anhydride Example #12 0.3:1 233 343 (40) Polyether
(Polytetrahydrofuran with Mn = 1100) Example #13 0.3:1 238 210 (25)
hexadecyltrimethylammonium p-toluene sulfonate Example #14 0.3:1
201 676 (68) .epsilon.-caprolactone
[0039] As is shown from Table 1, a number of tested antifouling
agents reduced the polymer produced while not greatly reducing the
catalytic activity. Table 2 depicts data regarding the reduction in
activity and the reduction in polymer produced based on the change
observed between the Comparative Example (which did not include an
antifouling agent) to each example which included an antifouling
additive.
TABLE-US-00002 TABLE 2 Activity Reduction (Negative is Polymer
Formation Experiment Number Activity Increase) Reduction
Comparative Example 0.0% 0.0% Example #1 -3.9% 95.8% Example #2
96.1% 100.0% Example #3 5.3% 92.6% Example #4 8.8% 92.7% Example #5
27.2% 85.7% Example #6 -6.1% 92.4% Example #7 -2.6% 88.9% Example
#8 -0.4% 77.9% Example #9 0.9% 73.0% Example #10 -0.9% 82.6%
Example #11 18.9% 89.2% Example #12 -2.2% 73.8% Example #13 -4.4%
84.0% Example #14 11.8% 48.4%
[0040] As is shown in Table 2, a number of antifouling agents
suppress polymer formation (for example, at least 5%, 10%, 20%,
30%, 40%, 50%, 60%, 70%, 80%, 90% or even 95% reduction) while not
greatly reducing activity (for example, less than or equal to 50%,
40%, 30%, 20%, 10% or even 5% reduction in activity, or even
increased activity).
[0041] It is noted that one or more of the following claims utilize
the term "where" as a transitional phrase. For the purposes of
defining the present technology, it is noted that this term is
introduced in the claims as an open-ended transitional phrase that
is used to introduce a recitation of a series of characteristics of
the structure and should be interpreted in like manner as the more
commonly used open-ended preamble term "comprising."
[0042] It should be understood that any two quantitative values
assigned to a property may constitute a range of that property, and
all combinations of ranges formed from all stated quantitative
values of a given property are contemplated in this disclosure.
[0043] Having described the subject matter of the present
disclosure in detail and by reference to specific embodiments
thereof, it is noted that the various details disclosed herein
should not be taken to imply that these details relate to elements
that are essential components of the various embodiments described
herein, even in cases where a particular element is illustrated in
each of the drawings that accompany the present description.
Rather, the claims appended hereto should be taken as the sole
representation of the breadth of the present disclosure and the
corresponding scope of the various embodiments described herein.
Further, it will be apparent that modifications and variations are
possible without departing from the scope of the appended
claims.
* * * * *