Catalyst composition and process for polymerizing polymers having multimodal molecular weight distribution
AssigneeMobil Oil Corporation
InventorsFrederick Y. Lo, Thomas E. Nowlin, Pradeep P. Shirodkar
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Abstract
There is disclosed a supported olefin polymerization catalyst composition comprising a precursor and a catalyst activator. The precursor comprises a magnesium compound, e.g., dibutylmagnesium, a cyclopentadienyl group-containing zirconium compound, and a titanium and/or a vanadium compound, e.g., TiCl.sub.4, and an organic compound, e.g., an alcohol. The catalyst activator is a mixture of a conventional Ziegler/Natta co-catalyst and a zirconium sites activator, e.g., methylaluminumoxane. The catalyst is used in the presence of small amounts of hydrogen to produce polymers having multimodal molecular weight distribution in a single reactor.
Claims19
An olefin polymerization catalyst precursor composition supported on a porous carrier which has active OH groups comprising a magnesium compound, a zirconium compound, and TiCl.sub.4, wherein the magnesium compound has the formula:
- Mg(OR).sub.2, R.sup.1.sub.m MgR.sup.2.sub.n or R.sup.3.sub.k MgX.sub.(2-k)
- where R, R.sup.1, R.sup.2, and R.sup.3 each are each alkyl groups, X is a halogen, m and n are each 0, 1 or 2, providing that m+n equals the valence of Mg, and k is 0, 1, or 2;
- and wherein the zirconium compound has the formula
- Cp.sub.m ZrY.sub.n X.sub.(2-m)
- wherein Cp is cyclopentadienyl, m is 1, 2 or 3, Y and X are each the same or different halogen, a C.sub.1 -C.sub.6 alkyl or hydrogen and n is 0 or 1, which is produced by impregnating a reaction product of said carrier and said magnesium compound with said zirconium compound;
- wherein the reaction product is treated with said titanium compound prior to impregnating.
A method of synthesizing an olefin polymerization catalyst precursor composition comprising contacting a solid, porous carrier having reactive OH groups with a magnesium compound, a zirconium compound, and a compound selected from the group consisting of titanium compounds, vanadium compounds and mixtures thereof;
- wherein the magnesium compound has the formula:
- Mg(OR).sub.2, R.sub.m.sup.1 MgR.sub.n.sup.2, or R.sub.k.sup.3 MgX.sub.(2-k)
- where R, R.sup.1, R.sup.2 and R.sup.3 are each alkyl groups, X is a halogen, k, m, and n are each 0, 1, or 2, providing that m+n equals the valence of Mg;
- the zirconium compound has the formula Cp.sub.m ZrY.sub.n X.sub.(2-n)
- wherein Cp is cyclopentadienyl, m is 1, 2 or 3, Y and X are each a halogen, a C.sub.1 -C.sub.6 alkyl or hydrogen, and n is 0 or 1;
- the titanium compound is a titanium halide and the vanadium compound is a vanadium halide, a vanadium oxyhalide or mixtures thereof;
- wherein the contacting is conducted in the presence of an organic solvent in the magnesium compound, the zirconium compound, the titanium compound, the vanadium compound, or mixtures of the titanium and vanadium compounds are soluble;
- wherein the solid, porous carrier is contacted with the zirconium compound in the presence of an aluminoxane compound of the formula ##STR13## for a linear aluminoxane, where n is 0 to 50 and/or
- (Al(R)--O).sub.m
- for a cyclic aluminoxane, wherein m is an integer from 3 to 50, and R for both the linear and the cyclic aluminoxane is the same or different linear, branched or cyclic C.sub.1 -C.sub.12 alkyl group, which process comprises reacting said carrier with said magnesium compound and titanium compound and, subsequently, undertaking contacting with said zirconium compound.
Dependencies are inferred from the claim text.