Borealis Technology Oy

Borealis A/s

Vidar Almquist

Arild Follestad

Harri Hokkanen

Tore Dreng

Kalle Kallio

Siw Bodil Fredriksen

Ulf Palmqvist

Espen Ommundsen

Paul Allemeersch

Ann Kristin Lindahl

Roger Goris

Ingrid Sorum Melaaen

Tone Aastad

A particulate, modified chromium oxide catalyst for the polymerisation of ethylene or ethylene with &agr;-olefins, comprising: a) a chromium-oxide catalyst, b) a transition metal compound, and c) a catalyst activator. A method for the preparation of the catalyst comprises the steps of: a) subjecting a chromium oxide catalyst precursor, which comprises a chromium oxide compound combined with an inorganic support, to a temperature in the range of from 400 to 950&deg; C. under oxidising conditions, and b) impregnating the obtained chromium catalyst with a catalyst activator and with a transition metal compound which comprises at least one cyclopentadienylic ring bonded to said transition metal and at least ligand selected from the group comprising alkoxy, amido and hydrocarbyl radicals, halogen and hybride bonded to said transition metal, which cyclopentadienylic ring may contain hetero atoms, be unsubstituted or substituted, be bonded to said transition metal through a bridge, and optionally annealed to other substituted or unsubstituted ring structures, and if two cyclopentadienyl rings are present they may be bonded to each other through a bridge, and c) subjecting the thus obtained particulate catalyst to drying conditions. This catalyst is suitable for producing polyethylenes under conditions of continuous feeding of all reactants.

Catalyst for the (co)polymerization of ethylene and a method for the preparation thereof

The invention provides a process for the preparation of a supported polymerization catalyst, said process comprising impregnating a porous particulate support in a mechanically fluidized state with a catalyst material.

Supported polymerization catalysts

Ths invention provides a process for the preparation of a polyethylene, in particular an HDPE suitable for blow moulding of HIC, which comprises polymerizing ethylene and, optionally an ethylenically unsaturated comonomer copolymerizable therewith, in the presence of a catalyst comprising a first silica-supported chromium catalyst having a pore volume of at least 2 mL/g, a surface area of at least 350 m /g and a chromium content of 0.1 to 1.0% by weight and a second silica-supported chromium catalyst having a pore volume of at least 2 mL/g, a surface area of at least 450 m /g and a chromium content of 0.1 to 1.0% by weight, wherein the silica support of said first catalyst also comprises alumina and the silica support of said second catalyst also comprises titanium, and preferably a co-catalyst.

Ethylene polymerization

A polyethylene produced by the homopolymerisation of ethylene or copolymerisation of ethylene with &agr;-olefins in the presence of a catalyst, characterized in that the fraction of low molecular weight polymers having MW<5000 g/mole is lower than 12% by weight of the produced polymer, and that the produced polyethylene has a measured melt strength expressed by a haul-off (HO) value satisfying the expression: HO>K &middot;&eegr;0.05&plus;K , wherein K is 9.10 and K is 0.4.

Polyethylenes obtained by use of dual site catalyst

A method for transitioning between two different catalysts in olefin polymerizations, a first catalyst and a second catalyst, comprising the steps of: discontinuing the feed of the first catalyst into the polymerization reactor, and introducing the second catalyst into the reactor, wherein the transition is performed between a chromium-based catalyst and a metallocene catalyst.

Method of catalyst transitions in olefin polymerizations

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Porsgrunn, Norway

Vidar Almquist