Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
1999-04-15
2002-04-16
Wu, David W. (Department: 1713)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S202000, C502S129000, C502S128000, C502S152000, C502S117000, C502S111000, C526S126000, C526S127000, C526S133000, C526S161000, C526S943000
Reexamination Certificate
active
06372684
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to new catalyst systems and to their use in the oligomerization and co-oligomerization of (&agr;-olefins; said catalyst systems are particularly useful in ethylene oligomerization in order to obtain &agr;-olefinic oligomers having from 4 to 24 carbon atoms.
PRIOR ART DISCLOSURE
High linear &agr;-olefins, i.e. (&agr;-olefins having from 4 to 24 carbon atoms, and more specifically 6 to 20 carbon atoms, are in great demand as intermediates in the preparation of detergents, lubricant additives and polyolefins; &agr;-olefins having 6-20 carbon atoms are suitable for a large number of applications in different technical fields. However, oligomerization processes commonly known in the state of the art lead to the obtainment, together with the target products, of undesirable by-products, such as internal olefins, branched olefins and olefins having a number of carbon atoms outside the above mentioned range.
Olefin polymerization processes employing homogeneous Ziegler-Natta catalyst systems or metallocene/alumoxane catalyst systems are well known in the state of the art; these catalyst systems are also used in oligomerization processes of lower olefins to give higher olefins.
For instance, the British patent application GB 135,873 describes the preparation of C
4
-C
20
linear &agr;-olefins by ethylene oligomerization in the presence of a catalyst composition comprising a divalent nickel salt, a boron hydride and a tertiary organophosphorus compound.
The international patent application WO 94/25416 discloses a catalyst system for the preparation of C
4
-C
24
linear &agr;-olefins comprising the reaction product of a bis-tetramethyl-cyclopentadienyl metallocene and a bulky, labile and non-coordinating anion.
Bridged bis-amido Group 4 (IUPAC 1988 notation) metal compounds are also known, as components of catalyst systems for the preparation of polyolefins, such as polyethylene and polypropylene. The international patent application WO 92/12162 discloses catalyst systems for the polymerization of &agr;-olefins, comprising an amido transition metal compound having the following formula:
wherein M is Ti, Zr or Hf; X is an univalent anionic ligand; the groups R, linked to trivalent N atoms, are selected from halogens and linear or branched hydrocarbon radicals, optionally containing one or more heteroatoms; T is a covalent unsubstituted or substituted hydrocarbon bridging group, optionally containing one element of Group IV-A or VI-A (Deming notation; corresponding to Group 14 and 16 of the IUPAC 1988 notation); y is 1 or 0; z is 2-y;
in association with an alumoxane.
Suitable alumoxanes are obtained by hydrolysis of a trialkylaluminium or haloalkylaluminium, such as trimethylaluminium, triethylaluminium and the corresponding chlorides; the most preferred alumoxane is methylalumoxane (MAO).
The catalysts disclosed in the above-mentioned WO 92/12162, which do not envisage amido compounds having a bridging group containing two heteroatoms, are used in the production of high molecular weight polyolefins, having a molecular weight well in excess of 100,000, and more specifically of high molecular weight isotactic polypropylene.
The international patent application WO 96/27439 describes a new class of oligomerization catalysts comprising a bridged bis-amido Group 4 metal compound, such as {1,2-bis(t-butylamide)tetramethyl-disilane{-zirconium dibenzyl or dimethyl, in association with suitable activating agents, capable of providing a bulky, labile and non-coordinating anion, containing at least one boron atom, such as B(C
6
F
5
)
3
or [Me
2
PhNH]
+
[B(C
6
F
5
)
4
]
−
.
These catalyst systems are active in the oligomerization or co-oligomerization of &agr;-olefins to produce linear &agr;-olefins. In the specification of WO 96/27439 it is mentioned the possibility of adding to the catalytic compositions further components, for example in order to increase the solubility and/or the stability of the same compositions, although not affecting the catalytic activity. For instance, it is mentioned the possibility of adding organoaluminium compounds, such as trimethylaluminium (TMA), triethylaluminium (TEA), triisopropylaluminium and triisobutylaluminium (TIBA), acting as scavenging agents, although without any influence of the catalytic activity of the system.
Nevertheless, there is room for improvement in the oligomerization yields when these catalyst systems are used. They tend to be sensitive to the presence of minor contaminants, resulting in low yields. In order to achieve a satisfactory activity the catalyst concentrations should not be too low, whereas relatively high concentrations may lead to exothermic reactions which are difficult to control. Further, the activity stability of the catalyst systems described in WO 96/27439 is not optimal, as shown by their activity decay.
Therefore, it is felt the need of lowering the decay rate and improving the catalytic activity of the above mentioned oligomerization catalysts, in order to allow their industrial exploitation.
SUMMARY OF THE INVENTION
The Applicant has now unexpectedly found that the catalytic activity in &agr;-olefin oligomerization of the above-mentioned bridged bis-amido Group 4 metal compounds, in association with boron activating compounds, can be surprisingly enhanced by adding to these components a specific class of branched alkylaluminiums and/or alumoxanes of branched alkylaluminiums, leading to &agr;-olefin oligomers having from 4 to 30 carbon atoms, in high yields and with a high selectivity towards &agr;-olefins.
More specifically, the present invention concerns a catalyst system for &agr;-olefin oligomerization comprising the product obtainable by contacting the following components:
(A) one or more bis-amido compounds having formula (I):
wherein M is Ti, Zr or Hf;
N is a trivalent nitrogen atom;
the Y atoms, the same or different from each other, are selected from the group consisting of Si, Ge and Sn;
the X groups, the same or different from each other, are selected from the group consisting of H, halogen, linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
1
-C
20
alkoxyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
6
-C
20
aryloxyl, C
7
-C
20
alkylaryl and C
7
-C
20
arylalkyl radicals, optionally containing one or more Si, Ge, O, S, P, B or N atoms; or two X groups form a ring having from 4 to 8 members;
R
1
, R
2
, R
3
, R
4
, R
5
and R
6
, the same or different from each other, are linear or branched, saturated or unsaturated C
1
-C
20
alkyl, C
3
-C
20
cycloalkyl, C
6
-C
20
aryl, C
7
-C
20
alkylaryl or C
7
-C
20
arylalkyl radicals, optionally containing one or more Si, Ge, O, S, P, B or N atoms; or are Si(R
7
)
3
groups, wherein the groups R
7
, the same or different from each other, are linear or branched, saturated or unsaturated C
1
-C
10
alkyl, C
3
-C
10
cycloalkyl, C
6
-C
15
aryl, C
7
-C
15
alkylaryl or C
7
-C
15
arylalkyl groups; or two or four substituents of R
1
, R
2
, R
3
, R
4
, R
5
and R
6
, linked to two vicinal atoms, form one or two rings having from 4 to 8 members;
Q is a neutral Lewis base; and
m is an integer ranging from 0 to 2;
said bis-amido compound being optionally present in the form of a dimer;
(B) one or more activating cocatalysts selected from:
compounds having formula Y
+
Z
−
, wherein Y
+
is a cation capable of reacting irreversibly with a substituent X of the compound of formula (I), and Z−is a compatible non-coordinating anion comprising at least one boron atom; and
neutral strongly Lewis acidic compounds comprising at least one boron atom;
(C) one or more compounds selected from the following classes:
(a) organometallic aluminium compounds having formula (II):
Al(CH
2
—CR
8
R
9
R
10
)
x
R
11
y
H
z
(II)
wherein, in the (CH
2
—CR
8
R
9
R
10
) groups, the same or different from each other, R
8
is a linear or branched, saturated or unsaturated C
1
-C
10
alkyl, C
3
-C
13
cycloalkyl or C
7
-C
16
alkylaryl radical; R
9
is a saturated o
Deuling Henderikus Hyacinthus
Horton Andrew D.
Ruisch Bart Johan
von Hebel Klaas L.
Choi Ling-Siu
Shell Oil Company
Wu David W.
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