Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
1999-07-15
2001-05-15
Wu, David W. (Department: 1713)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S104000, C502S113000, C502S117000, C502S125000, C502S152000, C526S114000, C526S116000, C526S119000, C526S160000, C526S127000, C526S351000
Reexamination Certificate
active
06232261
ABSTRACT:
BACKGROUND OF THE INVENTION
The present application relates to novel activators for catalysts in particular to novel activators for catalysts useful for the polymerization of olefins.
The use of activators or cocatalysts for olefin polymerization-catalysts is well known. For example aluminium alkyls have been used with Ziegler catalysts while aluminoxanes have been used widely with well-defined single site catalysts, for example metallocene catalysts.
The choice of activator for a commercial catalyst depends on many parameters, including performance, cost, safety and stability. There is therefore a need to widen the range of catalyst activators available for use with olefin polymerisation catalysts.
WO 93/13140 describes a catalyst system comprising a modified monocyclopentadienyl transition metal/aluminoxane catalyst system in which a modifier is used having a Lewis Base functionality for example an alkoxysilane. WO 94/20506 describes a method for carrying out a secondary hydrolysis on an aluminoxane to provide a new material having a specific viscosity.
We have now found a class of silicon containing compounds which may be used as activators for olefin polymerization catalysts in particular for use with metallocene catalysts.
SUMMARY OF THE INVENTION
Thus according to the present invention there is provided a catalyst system suitable for use in the polymerization of olefins comprising:
(A) an olefin polymerization catalyst, and
(B) the product of (i) an aluminoxane or (ii) the reaction product of an alkylaluminium compound and water, with a silicon-containing compound having the formula:
R
(4-x)
Si R
1
y
(OH)
x
wherein
R,R
1
=hydrocarbyl for example alkyl, aryl, alkenyl, or substituted hydrocarbyl
x=1 to 3, and
y=0 or 1.
DETAILED DESCRIPTION OF THE INVENTION
Suitable examples of the silicon-containing compound include trimethyl silanol, triethyl silanol, triphenylsilanol, dimethyl phenyl silanol, diphenyl methyl silanol, trimethyl silyl methanol, trimethyl silyl ethanol, trimethyl silyl propanol, dimethylphenylsilyl methanol, diphenylmethylsilyl methanol, dimethyl silane diol, diethyl silane diol and methyl ethyl silane diol.
Preferred activators are those where R is alkyl or aryl or subsituted alkyl or aryl, x=2 and y=0 For example compounds having the formula:
R
2
Si (OH)
2
.
Aryl silane diols are most preferred for example diphenyl silane diol, phenylmethyl silane diol etc.
When present the preferred R
1
group is alkyl in particular ethyl.
Suitable olefin polymerization catalysts are metallocene complexes which may be represented by the general formula:
(Cp)
m
MR
2
x
R
3
y
.
wherein Cp is a substituted or unsubstituted cyclopentadienyl nucleus; M is a Group IVA, VA or VIA transition metal in particular Zr, Ti, Hf; R
2
and R
3
are independently hydrocarbyl having 1-20 carbon atoms, halogen or other suitable monovalent ligand; m=1-3, x=0-3 and y=0-3 wherein the sum of m, x and y satisfy the oxidation state of M.
Particularly suitable are complexes in which the cyclopentadienyl nucleus is substituted by alkyl or alkenyl groups.
Examples of such metallocene catalysts may be found in the disclosures of EP 129368, U.S. Pat. No. 5,324,800 and EP 206794 incorporated herein by reference.
Also suitable for use as the metallocene are bridged complexes in which two cyclopentadienyl rings are linked via a suitable bridge.
Such complexes may be represented by the formula:
wherein Cp, M and R have the definitions given above the Z is a suitable bridging group eg alkylene, dialkylsilyl or dialkylgermanyl. In such complexes the cyclopentadienyl groups may be the same or different.
Particularly suitable are complexes having an alkylene bridge for example ethylene bis indenyl metal complexes such as ethylene (bis) indenyl zirconium dichloride.
The metallocene may also be represented by a monocyclopentadienyl heteroatom containing complex. Such complexes are disclosed for example in EP 416815 and EP 420436 both incorporated herein by reference.
The metallocene complex may also be represented by such monocyclopentadienyl complexes wherein the metal is in the +2 oxidation state. Such complexes are described in WO 95/00526 also incorporated herein by reference.
A further type of suitable metallocene complex are bis (cyclopentadienyl) diene complexes wherein the metal is in the +4 or +2 oxidation state. Such complexes are disclosed in WO 96/04290 also incorporated herein by reference.
Also suitable for use as the olefin polymerization catalyst of the present invention are traditional Ziegler Natta catalysts well known in the art. Typical catalysts of this type may be represented by transition metal/alkylaluminium systems for example catalysts based on magnesium, titanium and halogen.
Examples of suitable alkyl aluminium compounds are trialkylaluminium compounds (R
3
Al) for example:
trimethyl aluminium,
triethylaluminium,
tri-n-propyl-, tri-isopropyl aluminium,
tri-n-butyl, tri-iso-butyl aluminium,
tri-n-pentyl, tri-iso-pentyl aluminium,
tri-n-hexyl, tri-iso-hexyl aluminium,
triheptylaluminium,
trioctylaluminium, etc
Dialkylaluminium halides and alkyl aluminium dihalides may also be suitable, for example:
dimethyl aluminium chloride,
diethyl aluminium chloride,
dimethyl aluminium bromide,
methyl aluminium dichloride,
ethyl aluminium dichloride, etc.
The starting material in component (B) may be an aluminoxane or may be the reaction product of an alkyl aluminium compound described above with water. The water may be used as liquid, ice or water of crystallization eg aluminium sulphate hydrate.
The aluminoxane may suitably be methyl aluminoxane (MAO), ethyl aluminoxane or any other compound represented by the general formula (R-Al-O)
x
.
The component (B) of the catalyst system when water is present may suitably comprise the following molar ratios of constituents-silicon: aluminium: water in the range 1:0.5-100:0.1-200 preferably in the range 1:5-20:5-20.
The component (B) of the catalyst system may be prepared by controlled hydrolysis of the alkyl aluminium compound with water in a suitable solvent followed by addition of the silicon-containing compound. Alternatively the silicon-containing compound may be added to the aluminoxane in a suitable solvent.
Suitable solvents include inert hydrocarbons such as toluene.
The above preparation of component (B) may suitably take place at −78° C. to 120° C., preferably at −50° C. to 40° C.
The catalyst system according to the present invention may also comprise a second catalyst component for example another metallocene complex or a Ziegler catalyst component.
The catalyst system may further comprise an inert support for example silica, alumina, silica-alumina, magnesia, magnesium chloride.
The support may undergo a pretreatment to modify its surface eg thermal or chemical dehydroxylation.
The catalyst system when supported may be prepared by any suitable means well known in the art. A preferred support is silica.
For example a mixture of the components (A) and (B) in a suitable solvent may be added to a silica or a silica supported Ziegler catalyst.
The catalyst system according to the present invention is suitable for use in the polymerization of olefins in particular in the homopolymerization of ethylene or the copolymerisation of ethylene with one or more alpha-olefins in particular those having from 3 to 10 carbon atoms. Most preferred alpha olefins are 1-butene, 1-hexene and 4-methyl-1-pentene.
The catalyst system is useful for the polymerization of olefins in the solution, slurry or gas phase. The catalyst system is however most suitable for use in the gas phase.
The polymerization process may preferably take place in the presence of a further cocatalyst or scavenger for example a trialkylaluminium compound.
According to another aspect of the present invention there is provided an activator for use with an olefin polymerization catalyst said activator comprising the product of (i) an aluminoxane or (ii) the reaction product of an alkylaluminium compound and
BP Chemicals Limited
Finnegan, Henderson Farabow, Garrett and Dunner L.L.P.
Lu Caixia
Wu David W.
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