A system and method for charging a chromium-based catalyst to a mix vessel; introducing a reducing agent through an entrance arrangement into the mix vessel, and agitating a mixture of the chromium-based catalyst, the reducing agent, and a solvent in the mix vessel to promote contact of the reducing agent with the chromium-based catalyst to give a reduced chromium-based catalyst.

The present invention relates to A Ziegler-Natta catalyst component in the form of solid particles having a median a particle size (D50.sub.vol) of 5 to 200 μm and comprising i) a compound of Group 1 to 3, preferably of Group 2 metal, IUPAC, Nomenclature of Inorganic Chemistry, 1989 ii) a compound of a transition metal of Group 4 to 10, or of a lanthanide or actinide, preferably a transition metal of Group 4 to 6, IUPAC, Nomenclature of Inorganic Chemistry, 1989 and iii) an internal electron donor, wherein the solid particles a have a numerical SPAN of 0.80 or below and a ratio of numerical mode to volumetric mode (Mode.sub.num/Mode.sub.vol) of 0.60 or more and we Wherein Mode.sub.num<Mode.sub.vol. The invention also relates to a process for producing said catalyst component and use thereof producing C.sub.2 to C.sub.10 α-olefin polymers, especially propylene or ethylene polymers or copolymers thereof with α-olefins of 2 to 12 C-atoms.

Provided is a hybrid catalyst composition including a first transition metal compound represented by Formula 1 and a second transition metal compound represented by Formula 2, the compounds being different from each other in the Formulae. The hybrid catalyst composition including the first and second transition metal compounds may exhibit high catalytic activity and may prepare a polyolefin having processability and mechanical properties.

A catalyst mixture made from or containing (a) particles of a solid catalyst component comprising Ti, Mg, Cl, and (b) from 0.5 to 5.0% by weight, based upon the total weight of the mixture, of particles of a solid compound having particle size ranging from 0.1 μm to 1 mm containing more than 50% by weight of SiO.sub.2 units.

To produce an olefin-based polymer having a minor amount of decrease in bulk density due to heat.

A solid catalyst component for olefin polymerization containing a titanium atom, a magnesium atom, a halogen atom, and as internal electron donor, and having an envelope E1 calculated by the following Formula (1) in a range of 0.810 to 0.920.

E1=LE1/LS1   (1)

(In Formula, LE1 is a convex hull perimeter of the solid catalyst component for olefin polymerization obtained from an image of the solid catalyst component for olefin polymerization captured with a scanning electron microscope, and LS1 is an actual perimeter of the solid catalyst component for olefin. polymerization obtained from the image of the solid catalyst component for olefin polymerization captured with the scanning electron microscope.)

A solid catalyst component for polymerization of an olefin having a polymerization activity equivalent to or higher than a solid catalyst component having a phthalic acid ester compound or diether compound as an internal electron-donating compound, and can produce an olefin polymer having excellent bulk density and low content of olefin oligomers. A solid catalyst component for polymerization of an olefin is obtained by: (i) bringing compounds selected from particular phthalic acid ester compounds (A), a magnesium compound and a halogen-containing titanium compound into contact; (ii) bringing the first contact product obtained in step (i) and compounds selected from particular diether compounds (B) into contact, and washing the second contact product; and (iii) obtaining a contact product between the washed second contact product and a halogen-containing titanium compound, washing the contact product, and bringing it into contact with particular phthalic acid ester compounds (A) and a halogen-containing titanium compound.

The present invention relates to a process for producing a prepolymerized solid Ziegler-Natta catalyst in batch mode, a prepolymerized solid Ziegler-Natta catalyst, a process for producing a propylene polymer using said prepolymerized solid Ziegler-Natta catalyst, a prepolymerized solid Ziegler-Natta catalyst obtained by a process as well as the use of the prepolymerized solid Ziegler-Natta catalyst in a process for producing a propylene polymer.

The present invention relates to a polyethylene composition comprising a base resin having a density of from 952.0 kg/m.sup.3 to 960.0 kg/m.sup.3, determined according to ISO 1183, wherein the polyethylene composition has a melt flow rate MFR.sub.21 (190° C., 21.16 kg), of from 1.0 to 7.5 g/10 min, determined according to ISO 1133, a complex viscosity at a frequency of 0.05 rad/s eta0.05 of from 750 kPa #s to 1900 kPa #s, determined according to ISO 6721-1 and ISO 6721-10, and a white spot rating of not more than 12.0, determined according to ISO 18553, a polyethylene composition obtainable by a multi-stage process, a process for producing said polyethylene composition, an article, such as a pipe or pipe fitting, comprising said polyethylene composition and the use of said polyethylene composition for the production of an article.

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.

The invention relates to a solid catalyst system comprising a chromium compound, a metal compound, an aluminium compound and a silicon oxide support, wherein the silicon oxide support has an average particle diameter in the range between ≥20 and ≤50 μm, a pore volume in the range between ≥1.7 ml/g and ≤3 ml/g, and a surface area in the range between ≥400 m.sup.2/g and ≤800 m.sup.2/g, and wherein the aluminium alkoxide compound has the formula

R.sub.1—Al—OR.sub.2

wherein R.sub.1 is selected from (C.sub.1-C.sub.8) alkyl groups and OR.sub.2 is selected from (C.sub.1-C.sub.8) alkoxyl groups.