This invention relates to single site catalyst supportation methods involving high temperature treatment (≧40° C., e.g., 100-130° C.) to improve catalyst activity for olefin polymerization, e.g., propylene polymerization, and to the supported catalyst systems obtained by the methods, e.g., single site catalyst systems supported on a support having high average particle size (PS≧30 μm), high surface area (SA≧200 m.sup.2/g), low pore volume (PV≦2 mL/g), and a mean pore diameter range of 1≦PD≦20 nm.

A solid catalyst component for polymerization of olefins is disclosed which can produce a polymer having low stickiness (tackiness) of polymer particles, excellent flowability, and favorable particle size distribution. The solid catalyst component for polymerization of olefins includes titanium, magnesium, a halogen atom and an internal electron donor, wherein the solid catalyst component has a multimodal pore volume distribution measured by a mercury intrusion method and has one or more peak tops in each of a pore radius range from 0.002 μm to 1 μm and a pore radius range from larger than 1 μm to 30 μm or smaller, and a ratio represented by pore volume V1 derived from pores in the radius range from 0.002 μm to 1 μm/pore volume V2 derived from pores in the radius range from larger than 1 μm to 30 μm or smaller is 0.30 to 0.65.

A process for preparing a solid pre-catalyst component for use in olefinic polymerization includes dissolving a magnesium chloride in an alcohol and optionally adding water to form a first solution having a water content of about 0.5 mmol water per mol MgCl.sub.2 to about 100 mmol water per mol MgCl.sub.2; contacting the first solution with a first titanium compound to form the solid pre-catalyst component; and treating the solid pre-catalyst component with a hydrocarbon or halogenated hydrocarbon solvent, optionally containing a second titanium compound.

The present invention relates to a hybrid supported metallocene catalyst including at least first metallocene compound, at least one second metallocene compound, at least one cocatalyst compound, and a carrier, a preparation method therefor, and a polyolefin resin polymerized in the presence of the catalyst, wherein the second metallocene compound is a compound of a bridged structure having a ligand of an asymmetric structure, and the polyolefin resin has a density of 0.910 g/cm.sup.3 to 0.960 g/cm.sup.3, a molecular weight density in a unimodal distribution of 3 to 5, a melt index of 0.05 to 100 at 2.16 kg, and a melt flow rate of 20 to 40.

The present invention relates to a rotomolded article, comprising at least one metallocene-catalyzed polyethylene resin comprising at least two metallocene-catalyzed polyethylene fractions A and B, wherein the polyethylene resin comprises: at least 25% to at most 55% by weight of polyethylene fraction A based on the total weight of the polyethylene resin, wherein fraction A has a melt index MI2 of at least 25.0 g/10 min as determined according to ISO 1133, condition D, at 190° C. and under a load of 2.16 kg, and a density at least 0.005 g/cm.sup.3 higher than the density of the polyethylene resin; and wherein the polyethylene resin has a density of at least 0.938 g/cm.sup.3 to at most 0.950 g/cm.sup.3 as measured according to ASTM D-1505 at 23° C.; a melt index MI2 of at least 1.0 g/10 min to at most 25.0 g/10 min as determined according to ISO 1133, condition D, at 190° C. and under a load of 2.16 kg.

The present invention also relates to a process for preparing said rotomolded article.

The present invention describes a process for preparing catalyst for the polymerization of ethylene consisting essentially of the steps of (i) contacting a magnesium based precursor with a solvent; and (ii) then contacting the magnesium based precursor in the solvent with a transition metal compound to obtain the catalyst, wherein step (ii) is single contact step. The present invention also relates to a process for preparation of a catalyst system and a process of polymerizing and/or copolymerizing of ethylene to obtain a polyethylene using the catalyst.

Catalyst preparation systems and methods for preparing reduced chromium catalysts are disclosed, and can comprise irradiating a supported chromium catalyst containing hexavalent chromium with a light beam having a wavelength within the UV-visible light spectrum. Such reduced chromium catalysts have improved catalytic activity compared to chromium catalysts reduced by other means. The use of the reduced chromium catalyst in polymerization reactor systems and olefin polymerization processes also is disclosed, resulting in polymers with a higher melt index.

An olefin polymerisation method and arrangement comprising polymerising at least one olefin in gas phase in a fluidised bed in the presence of an olefin polymerisation catalyst in a polymerisation reactor having a vertical body; a generally conical downwards tapering bottom zone; a generally cylindrical middle zone, above and connected to said bottom zone; and a generally conical upwards tapering top zone above and connected to said middle zone wherein (i) fluidisation gas is introduced to the bottom zone of the reactor from where it passes upwards through the reactor; (ii) the fluidisation gas is withdrawn from the top zone of the reactor; (iii) a fluidised bed is formed within the reactor where the growing polymer particles are suspended in the upwards rising gas stream; and wherein the polymerisation reactor has an operating temperature set point and which reactor comprises at least one temperature measurement sensor, wherein a temperature difference (DT) between the temperature measurement sensor (Tm), and the operating temperature set point (Ts) of the reactor is equal to or less than 10° C.

Silica-coated alumina activator-supports, and catalyst compositions containing these activator-supports, are disclosed. Methods also are provided for preparing silica-coated alumina activator-supports, for preparing catalyst compositions, and for using the catalyst compositions to polymerize olefins.

A Ziegler-Natta catalyst component precursor made from or containing a mechanical mixture of (a) distinct particles of adducts of formula MgCl.sub.2(R.sup.1OH).sub.n where R is a C.sub.1-C.sub.8 alkyl group and n is from 0.2 to 6 having average particle size (P50a) ranging from 5 to 100 μm; and (b) from 0.2 to 5.0% by weight of distinct particles of a solid compound containing more than 50% by weight of Sift units and having average particle size (P50b), wherein the ratio P50b/P50a ranges from 0.4 to 1.5.